2,450 results on '"PHYSICS, APPLIED"'
Search Results
2. On the Stability of Electrohydrodynamic Jet Printing Using Poly(ethylene oxide) Solvent-Based Inks
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Enginyeria Química, Universitat Rovira i Virgili, Ramon, A; Liashenko, I; Rosell-Llompart, J; Cabot, A, Enginyeria Química, Universitat Rovira i Virgili, and Ramon, A; Liashenko, I; Rosell-Llompart, J; Cabot, A
- Abstract
Electrohydrodynamic (EHD) jet printing of solvent-based inks or melts allows for the producing of polymeric fiber-based two- and three-dimensional structures with sub-micrometer features, with or without conductive nanoparticles or functional materials. While solvent-based inks possess great material versatility, the stability of the EHD jetting process using such inks remains a major challenge that must be overcome before this technology can be deployed beyond research laboratories. Herein, we study the parameters that affect the stability of the EHD jet printing of polyethylene oxide (PEO) patterns using solvent-based inks. To gain insights into the evolution of the printing process, we simultaneously monitor the drop size, the jet ejection point, and the jet speed, determined by superimposing a periodic electrostatic deflection. We observe printing instabilities to be associated with changes in drop size and composition and in the jet's ejection point and speed, which are related to the evaporation of the solvent and the resulting drying of the drop surface. Thus, stabilizing the printing process and, particularly, the drop size and its surface composition require minimizing or controlling the solvent evaporation rate from the drop surface by using appropriate solvents and by controlling the printing ambient. For stable printing and improved jet stability, it is essential to use polymers with a high molecular weight and select solvents that slow down the surface drying of the droplets. Additionally, adjusting the needle voltages is crucial to prevent instabilities in the jet ejection mode. Although this study primarily utilized PEO, the general trends observed are applicable to other polymers that exhibit similar interactions between solvent and polymer.
- Published
- 2024
3. Low Cost, Flexible, Room Temperature Gas Sensor: Polypyrrole-Modified Laser-Induced Graphene for Ammonia Detection
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Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Santos-Ceballos JC; Salehnia F; Romero A; Vilanova X; Llobet E, Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, and Santos-Ceballos JC; Salehnia F; Romero A; Vilanova X; Llobet E
- Abstract
The electrochemical synthesis of polypyrrole (PPy) on laser-induced graphene (LIG) electrodes is investigated in this study, along with the gas sensing applications of these modified laser-tailored materials. A simple and scalable method for the low-cost, large-scale production of polypyrrole LIG nanocomposites (PPy@LIG NCs) is proposed. This nanocomposite is subsequently applied to design chemo-resistive flexible gas sensors to detect ammonia (NH3) levels at room temperature. Following a brief gas exposure, PPy@LIG NCs sensors demonstrate changes in resistance with a sensitivity 14 times higher than that of pure LIG. Moreover, excellent repeatability in results and a low detection limit of 1 ppm were achieved. The LIG formation and electrochemical synthesis of PPy were confirmed through Raman spectroscopy and FTIR spectroscopy. The analysis by FE-SEM and TEM verified the formation of PPy@LIG NCs. In conclusion, this work introduces the novel PPy@LIG nanocomposites and its application in gas sensing, showcasing their unique selectivity, enhanced sensitivity, and cost-effective production. These attributes mark a significant step forward, presenting new possibilities for the development of advanced gas-sensing systems aimed at improving air quality monitoring.
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- 2024
4. Bayesian Active Learning for Received Signal Strength-Based Visible Light Positioning
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Federico Garbuglia, Willem Raes, Jorik De Bruycker, Nobby Stevens, Dirk Deschrijver, and Tom Dhaene
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Technology ,Technology and Engineering ,Science & Technology ,machine learning (ML) ,Physics ,active learning (AL) ,INDOOR ,Engineering, Electrical & Electronic ,Optics ,adaptive sampling ,LOCALIZATION ,Atomic and Molecular Physics, and Optics ,Physics, Applied ,Engineering ,Gaussian processes (GP) ,SYSTEMS ,Gaussian ,processes (GP) ,Physical Sciences ,Visible Light Positioning (VLP) ,ALGORITHM ,Electrical and Electronic Engineering - Abstract
Visible Light Positioning (VLP) is a promising indoor localization technology for providing highly accurate positioning. In this work, a VLP implementation is employed to estimate the position of a vehicle in a room using the Received Signal Strength (RSS) and fixed LED-based light transmitters. Classical VLP approaches use lateration or angulation based on a wireless propagation model to obtain location estimations. However, previous work has shown that machine learning models such as Gaussian processes (GP) achieve better performance and are more robust in general, particularly in presence of non-ideal environmental conditions. As a downside, Machine Learning (ML) models require a large collection of RSS samples, which can be time-consuming to acquire. In this work, a sampling scheme based on active learning (AL) is proposed to automate the vehicle motion and to accelerate the data collection. The scheme is tested on experimental data from a RSS-based VLP setup and compared with different settings to a simple random sampling.
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- 2022
5. Simulation of an Ultrafast Charging Station Operating in Steady State
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Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Blanch-Fortuna, A; Zambrano-Prada, D; Gállego-Casals, M; Martinez-Salamero, L, Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, and Blanch-Fortuna, A; Zambrano-Prada, D; Gállego-Casals, M; Martinez-Salamero, L
- Abstract
This report presents the analysis, study, and simulation of an ultrafast charging station (UFCS) for electric vehicles (EVs) operating in steady state. The electrical architecture of the charging station uses an ac bus plus two dc buses and it is supported by a storage system based on batteries and super-capacitors. The power demand of the EVs is established taking into account the electric characteristics of their batteries and the availability of the station charging points. The analysis introduces a supervisory control based on a state machine description for different operating modes, which eventually facilitates fault detection in the electrical architecture. In addition, the study proposes different methods to handle the required energy for the charging demand and a procedure for the correct sizing of both the energy storage system and the input transformer. In laboratory experiments in a reduced-scale storage system, a SCADA supervision with CAN communication has proved successful in gathering data corresponding to modes of charge and discharge in batteries and super-capacitors, and subsequently displaying them on a computer screen.
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- 2023
6. Temperature-Dependent Sheet Resistance and Surface Characterization of Thin Copper Films Bonded to FR4 Composite under Mechanical Vibrations
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Universitat Rovira i Virgili, Azam, S; Munshi, S; Hassan, MK; Fragoso, A, Universitat Rovira i Virgili, and Azam, S; Munshi, S; Hassan, MK; Fragoso, A
- Abstract
Featured Application: Electrical and electronic devices that experience long-term vibrations. Electrical boards, also called printed circuit boards, constitute the basis of most electronic devices. These boards are mainly fabricated of thin copper films bonded to fiber epoxy laminates, such as FR4. Being the most important functional component of these devices, they sometimes undergo mechanical stresses such as shock and vibration during transport and operation that can induce electrical failure and malfunction; hence, studies addressing the effects of vibrations on their electrical properties have important applications. In this paper, small cantilever samples made of bare copper bonded to FR4 with three isolated rectangular zones were studied to analyze, for the first time, variations in electrical properties such as sheet resistance and resistivity before and after 200 k, 500 k, and 800 k vibration cycles at three different temperatures (25, 35, and 45 °C). A significant rise in resistance equivalent to 1657% of the initial value was observed from 0 to 800 k vibration cycles. These changes were accompanied by a 95% decrease in conductivity, from 4.1 × 107 to 2.3 × 106 S/m, whereas very little change in the electrical properties was observed due to temperature rise. Surface analysis by ESEM showed cracks ~1 µm in width and several millimeters in length with a crack density of ~8 cracks per mm after 800 k cycles. The surface composition (100% copper) was not altered even upon a high number of vibration cycles, and static drop contact angle measurements of 117–119 degrees indicated an increase in the hydrophobicity of the surface attributed to increased surface roughness and the accumulation of very small air bubbles on the cracks.
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- 2023
7. Approaching Self-Bonded Medium Density Fiberboards Made by Mixing Steam Exploded Arundo donax L. and Wood Fibers: A Comparison with pMDI-Bonded Fiberboards on the Primary Properties of the Boards
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Universitat Rovira i Virgili, Vitrone, F; Brinker, S; Ramos, D; Ferrando, F; Salvadó, J; Mai, C, Universitat Rovira i Virgili, and Vitrone, F; Brinker, S; Ramos, D; Ferrando, F; Salvadó, J; Mai, C
- Abstract
This study presents an unexplored method to produce formaldehyde-free MDF. Steam exploded Arundo donax L. (STEX-AD) and untreated wood fibers (WF) were mixed at different mixing rates (0/100, 50/50, and 100/0, respectively) and two series of boards were manufactured, with 4 wt% of pMDI, based on dry fibers, and self-bonded. The mechanical and physical performance of the boards was analyzed as a function of the adhesive content and the density. The mechanical performance and dimensional stability were determined by following European standards. The material formulation and the density of the boards had a significant effect on both mechanical and physical properties. The boards made solely of STEX-AD were comparable to those made with pMDI, while the panels made of WF without adhesive were those that performed the worst. The STEX-AD showed the ability to reduce the TS for both pMDI-bonded and self-bonded boards, although leading to a high WA and a higher short-term absorption for the latter. The results presented show the feasibility of using STEX-AD in the manufacturing of self-bonded MDF and the improvement of dimensional stability. Nonetheless, further studies are needed especially to address the enhancement of the internal bond (IB).
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- 2023
8. Cryogenic laser operation of a “mixed” Yb:LuYAG garnet crystal
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Universitat Rovira i Virgili, Slimi S; Jambunathan V; Pan M; Wang Y; Chen W; Loiko P; Solé RM; Aguiló M; Díaz F; Smrz M; Mocek T; Mateos X, Universitat Rovira i Virgili, and Slimi S; Jambunathan V; Pan M; Wang Y; Chen W; Loiko P; Solé RM; Aguiló M; Díaz F; Smrz M; Mocek T; Mateos X
- Abstract
We report on the continuous-wave and passively Q-switched operation of a compositionally “mixed” heavily doped 16.6 at.% Yb:(Y,Lu)3Al5O12 garnet crystal at cryogenic temperatures (100–200 K), pumped by a volume Bragg grating stabilized diode laser emitting at 969 nm. At 140 K, in the continuous-wave regime, a maximum output power of 10.65 W was achieved at ~ 1029 nm with a slope efficiency of 56% (versus the incident pump power), a laser threshold of 1.05 W and excellent beam quality. Using Cr4+:YAG as a saturable absorber, the passively Q-switched laser generated pulses with an energy/duration of 0.15 mJ/201 ns, respectively, at a repetition rate of 39.7 kHz, corresponding to a peak power of 0.39 kW.
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- 2023
9. Breathable Lignin Nanoparticles as Reversible Gas Swellable Nanoreactors
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Universitat Rovira i Virgili, Moreno A; Delgado-Lijarcio J; Ronda JC; Cádiz V; Galià M; Sipponen MH; Lligadas G, Universitat Rovira i Virgili, and Moreno A; Delgado-Lijarcio J; Ronda JC; Cádiz V; Galià M; Sipponen MH; Lligadas G
- Abstract
The design of stimuli-responsive lignin nanoparticles (LNPs) for advanced applications has hitherto been limited to the preparation of lignin-grafted polymers in which usually the lignin content is low (<25 wt.%) and its role is debatable. Here, the preparation of O2-responsive LNPs exceeding 75 wt.% in lignin content is shown. Softwood Kraft lignin (SKL) is coprecipitated with a modified SKL fluorinated oleic acid ester (SKL-OlF) to form colloidal stable hybrid LNPs (hy-LNPs). The hy-LNPs with a SKL-OlF content ranging from 10 to 50 wt.% demonstrated a reversible swelling behavior upon O2/N2 bubbling, increasing their size – ≈35% by volume – and changing their morphology from spherical to core-shell. Exposition of hy-LNPs to O2 bubbling promotes a polarity change on lignin-fluorinated oleic chains, and consequently their migration from the inner part to the surface of the particle, which not only increases the particle size but also endows hy-LNPs with enhanced stability under harsh conditions (pH < 2.5) by the hydration barrier effect. Furthermore, it is also demonstrated that these new stimuli-responsive particles as gas tunable nanoreactors for the synthesis of gold nanoparticles. Combining a straightforward preparation with their enhanced stability and responsiveness to O2 gas these new LNPs pave the way for the next generation of smart lignin-based nanomaterials.
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- 2023
10. Cryogenic Tm:LiYF4 laser around 2 µm
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Universitat Rovira i Virgili, Alles, A; Jambunathan, V; Slimi, S; Serres, JM; Aguiló, M; Díaz, F; Mateos, X; Smrz, M; Mocek, T, Universitat Rovira i Virgili, and Alles, A; Jambunathan, V; Slimi, S; Serres, JM; Aguiló, M; Díaz, F; Mateos, X; Smrz, M; Mocek, T
- Abstract
We present the laser characteristics of a 5 at.% Tm:YLF crystal using a modular setup at cryogenic temperatures emitting around 2 µm. Continuous-wave laser operation was achieved by pumping the laser crystal using a Volume Bragg Grating-stabilized laser diode emitting at 793 nm. A maximum output power of 6.5 W was achieved at 80 K corresponding to a slope efficiency of 66.0% with respect to the absorbed power with excellent beam quality.
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- 2023
11. Morphological Integration on the Calcaneum of Domestic Sheep (Ovis aries Linnaeus, 1758)—A Geometric Morphometric Study
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Universitat Rovira i Virgili, Parés-Casanova, PM; Rissech, C; Davis, S; Lloveras, L, Universitat Rovira i Virgili, and Parés-Casanova, PM; Rissech, C; Davis, S; Lloveras, L
- Abstract
Morphological integration and modularity refer to the degree of covariation between the different components of an anatomical structure. Modularity refers to structures that have components which covary strongly, but at the same time are relatively independent. Integration refers to the coordinated variation of the components of a functional anatomical structure. The hindlimb basipodium is a complex functional structure. The integration of its parts must arise from a coordinated development and functionality. Our objective in this study was to study the levels of integration of two modules on the calcaneum in domestic sheep. The calcaneum develops from two different centres. One gives rise to the body and its process while the other gives rise to the distal half of the bone. The hypothesis of modularity of two parts of the calcaneum was tested using the Escoufier RV coefficient and an analysis of two blocks of Partial Least Squares. These allowed us to evaluate the level of morphological integration. For this purpose, digital images of the medial aspect of complete calcanea of 47 domestic sheep (Ovis aries) were used. Twenty 2D coordinates of homologous anatomical landmarks (4 for the body and the process and 16 for the distal half of the bone) were collected as morphometric data. These were studied using geometric morphometrics. The results indicated good evidence of modular organization and a medium morphological integration between the two modules. Thus, according to our results, the two modules seem to exist and behave in a rather independent way. They appear to share functions rather than precursors of development. This study is important in order to elucidate the underlying factors in the processes of the development of the sheep calcaneum.
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- 2023
12. Continuous-Wave and Mode-Locked Operation of an In-Band Pumped Tm,Ho,Lu:CaGdAlO4 Laser
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Universitat Rovira i Virgili, Zeng, HJ; Xue, WZ; Murray, RT; Chen, WD; Pan, ZB; Wang, L; Cui, C; Loiko, P; Mateos, X; Griebner, U; Petrov, V, Universitat Rovira i Virgili, and Zeng, HJ; Xue, WZ; Murray, RT; Chen, WD; Pan, ZB; Wang, L; Cui, C; Loiko, P; Mateos, X; Griebner, U; Petrov, V
- Abstract
We investigate in-band pumping of a Tm,Ho,Lu:CaGdAlO4 laser using a Raman-shifted Er-fiber laser (1678 nm), in the continuous-wave (CW) and mode-locked (ML) regimes. A maximum output power of 524 mW is obtained in the CW regime with a 5% output coupler at an absorbed pump power of 2.04 W, corresponding to a slope efficiency of 27.9%. A maximum CW wavelength tuning range of 160 nm at the zero level, from 1984 to 2144 nm, is obtained with a 0.2% output coupler. In the ML regime, pumping with 5.5 W (unpolarized), the average output power (0.2% output coupler) reaches 148 mW at a repetition rate of similar to 96 MHz. The output spectrum is centered at 2071.5 nm with a FWHM of 21.5 nm (sigma-polarization). The pulse duration amounts to 218 fs (time-bandwidth product equal to 0.327).
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- 2023
13. A Unified Switched Nonlinear Dynamic Model of an Electric Vehicle for Performance Evaluation
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Universitat Rovira i Virgili, Khan, D; Mandal, K; Ray, AK; El Aroudi, A, Universitat Rovira i Virgili, and Khan, D; Mandal, K; Ray, AK; El Aroudi, A
- Abstract
The advanced modeling and estimation of overall system dynamics play a vital role in electric vehicles (EVs), as the selection of components in the powertrain and prediction of performance are the key market qualifiers. The state-space averaged model and small-signal transfer function model are useful for assessing long-term behavior in system-level analysis and for designing the controller parameters, respectively. Both models take less computation time but ignore the high-frequency switching dynamics. Therefore, these two models could be impractical for the development and testing of EV prototypes. On the other hand, the multi-domain model in available simulation tools gives in-depth information about the short-term behavior and loss analysis of power electronic devices in each subsystem, considering the switching dynamics in a long computation time. In this paper, a general mathematical framework for the dynamical analysis of complete EVs is presented using a unified, switched nonlinear model. This equation-based model runs faster than the available module-based simulation tools. Two other models, namely the time domain state-space averaged model and frequency domain small-signal transfer function model, are also developed from the switched nonlinear model for the analysis with less computation time. The design and performance of an EV with two different motors and its controllers are evaluated using the general mathematical framework.
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- 2023
14. Characterization of Asphalt Binders Modified with Bio-Binder from Swine Manure
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Universitat Rovira i Virgili, Gasia, J; López-Montero, T; Vidal, L; Miró, R; Bengoa, C; Martínez, AH, Universitat Rovira i Virgili, and Gasia, J; López-Montero, T; Vidal, L; Miró, R; Bengoa, C; Martínez, AH
- Abstract
Asphalt is an essential material in the construction of asphalt pavements. Due to its high demand and dependence on petroleum, it is crucial to use greener materials that can fully or partially replace petroleum-based binders. The characteristics of asphalt cause the bio-binder obtained through a hydrothermal liquefaction process from swine manure to have great potential to be used as a modifier due to its similarities with asphalt, contributing to the construction of more sustainable roads. Thus, this paper characterizes an asphalt binder modified with a new bio-binder obtained from swine manure at different rates (0%, 10%, and 20%). Several characterization tests were performed, including penetration, ring and ball, Fraass, viscosity, Cleveland open cup, and the UCL method. Furthermore, the possible leaching of the bio-binder was studied, showing no environmental problems. Results from the rheological tests showed that as the content of bio-binder increases, the softening temperature, Fraass breaking point, and viscosity of the bio-modified asphalt binder decrease, indicating the lower consistency of the bio-modified binder and its greater thermal susceptibility.
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- 2023
15. Nano/Micromotor-Driven SERS for Highly Sensitive and Spatially Controlled Sensing
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Química Física i Inorgànica, Universitat Rovira i Virgili, Becerril-Castro, IB; Salgueiriño, V; Correa-Duarte, MA; Alvarez-Puebla, RA, Química Física i Inorgànica, Universitat Rovira i Virgili, and Becerril-Castro, IB; Salgueiriño, V; Correa-Duarte, MA; Alvarez-Puebla, RA
- Abstract
Nano/micromotors (NMs) are tiny structures capable of converting various forms of energy into mechanical motion at the micro and nanoscale. These motors operate in environments characterized by low inertia and low Reynolds numbers. The potential applications of NMs are vast, particularly in the fields of biomedicine and environmental science. One of the most intriguing developments in this field is the integration of NMs with surface-enhanced Raman scattering (SERS) spectroscopy. SERS is a powerful analytical technique that enhances the Raman intensity of molecules, allowing for highly sensitive detection and analysis of trace amounts of substances. This integration offers highly precise and localized ultrasensing capabilities. The combination of NMs with SERS can also facilitate real-time imaging inside living organisms. This has immense potential in chemical and cell biology and medical diagnostics and prognosis. Herein this review describes the types of NMs and their fabrication, the incorporation of plasmonic nanostructures, capable of creating strong electromagnetic fields when illuminated by light, which in turn enhances the Raman signals significantly, their applications, and their future prospects in areas such as precision medicine, environmental monitoring, and possibly even in new realms like microscale robotics and targeted therapeutics.This review investigates the synergistic integration of SERS and nano/micromotors, showcasing their combined applications in bioanalytical sensing, environmental monitoring, and nanoscale imaging. Furthermore, future prospects and challenges are discussed, emphasizing the crucial role of ongoing research in fully realizing the potential of SERS and nano/micromotors.image
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- 2023
16. Design of Flame-Made ZnZrOx Catalysts for Sustainable Methanol Synthesis from CO2
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Química Física i Inorgànica, Universitat Rovira i Virgili, Araujo, TP; Morales-Vidal, J; Zou, TS; Agrachev, M; Verstraeten, S; Willi, PO; Grass, RN; Jeschke, G; Mitchell, S; Lopez, N; Perez-Ramirez, J, Química Física i Inorgànica, Universitat Rovira i Virgili, and Araujo, TP; Morales-Vidal, J; Zou, TS; Agrachev, M; Verstraeten, S; Willi, PO; Grass, RN; Jeschke, G; Mitchell, S; Lopez, N; Perez-Ramirez, J
- Abstract
Mixed zinc-zirconium oxides, ZnZrOx, are highly selective and stable catalysts for CO2 hydrogenation to methanol, a pivotal energy vector. However, their activity remains moderate, and descriptors to design improved systems are lacking. This work applies flame spray pyrolysis (FSP), a one-step and scalable method, to synthesize a series of ZnZrOx catalysts, and systematically compares them to coprecipitated (CP) analogs to establish deeper synthesis-structure-performance relationships. FSP systems (up to 5 mol%) generally display a threefold higher methanol productivity compared to their CP counterparts. In-depth characterization and theoretical simulations show that, unlike CP, FSP maximizes the surface area and formation of atomically dispersed Zn2+ sites incorporated in lattice positions within the ZrO2 surface, which is key to improving performance. Analysis by in situ electron paramagnetic resonance (EPR) spectroscopy reveals that the specific architecture of the flame-made catalyst markedly fosters the generation of oxygen vacancies. Together with surrounding Zn and Zr-O atoms, the oxygen vacancies create active ensembles that favor methanol formation through the formate path while suppressing undesired CO production, as confirmed by kinetic modeling. This study elucidates the nature of active sites and their working mechanism, pushing forward ZnZrOx-catalyzed methanol synthesis by providing a new benchmark for this cost-effective and earth-abundant catalyst family.
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- 2023
17. Beyond Protocols: Understanding the Electrical Behavior of Perovskite Solar Cells by Impedance Spectroscopy
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Universitat Rovira i Virgili, Ghahremanirad, E; Almora, O; Suresh, S; Drew, AA; Chowdhury, TH; Uhl, AR, Universitat Rovira i Virgili, and Ghahremanirad, E; Almora, O; Suresh, S; Drew, AA; Chowdhury, TH; Uhl, AR
- Abstract
Impedance spectroscopy (IS) is an effective characterization technique used to probe and distinguish charge dynamics occurring at different timescales in optoelectronic and electric devices. With the rapid rise of research being conducted on perovskite solar cells (PSCs), IS has significantly contributed to the understanding of their device performance and degradation mechanisms, including metastable effects such as current–voltage hysteresis. The ionic–electronic behavior of PSCs and the presence of a wide variety of perovskite compositions and cell architectures add complexity to the accurate interpretation of the physical processes occurring in these devices. In this review, the most common IS protocols are explained to help perform accurate impedance measurements on PSC devices. It critically reviews the most commonly used equivalent circuits alongside drift-diffusion modeling as a complementary technique to analyze the impedance response of PSCs. As an emerging method for characterizing the interfacial recombination between the perovskite layer and selective contacts, light intensity modulated impedance spectroscopy technique is further discussed. Lastly, important works on the application of IS measurement protocols for PSCs are summarized followed by a detailed discussion, providing a critical perspective and outlook on the growing topic of IS on PSCs.
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- 2023
18. Balancing Near-Field Enhancement and Hot Carrier Injection: Plasmonic Photocatalysis in Energy-Transfer Cascade Assemblies
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Universitat Rovira i Virgili, Negrín-Montecelo, Y; Geneidy, AHA; Govorov, AO; Alvarez-Puebla, RA; Besteiro, LV; Correa-Duarte, MA, Universitat Rovira i Virgili, and Negrín-Montecelo, Y; Geneidy, AHA; Govorov, AO; Alvarez-Puebla, RA; Besteiro, LV; Correa-Duarte, MA
- Abstract
Photocatalysis stands as a very promising alternative to photovoltaics in exploiting solar energy and storing it in chemical products through a single-step process. A central obstacle to its broad implementation is its low conversion efficiency, motivating research in different fields to bring about a breakthrough in this technology. Using plasmonic materials to photosensitize traditional semiconductor photocatalysts is a popular strategy whose full potential is yet to be fully exploited. In this work, we use CdS quantum dots as a bridge system, reaping energy from Au nanostructures and delivering it to TiO2 nanoparticles serving as catalytic centers. The quantum dots can do this by becoming an intermediate step in a charge-transfer cascade initiated in the plasmonic system or by creating an electron-hole pair at an improved rate due to their interaction with the enhanced near-field created by the plasmonic nanoparticles. Our results show a significant acceleration in the reaction upon combining these elements in hybrid colloidal photocatalysts that promote the role of the near-field enhancement effect, and we show how to engineer complexes exploiting this approach. In doing so, we also explore the complex interplay between the different mechanisms involved in the photocatalytic process, highlighting the importance of the Au nanoparticles’ morphology in their photosensitizing capabilities.
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- 2023
19. Spectroscopic and lasing characteristics of Yb:YGG at cryogenic temperatures
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Química Física i Inorgànica, Universitat Rovira i Virgili, Slimi S; Jambunathan V; Zin Elabedine G; Yu H; Zhang H; Chen W; Maria Solé R; Aguiló M; Díaz F; Smrz M; Mocek T; Mateos X, Química Física i Inorgànica, Universitat Rovira i Virgili, and Slimi S; Jambunathan V; Zin Elabedine G; Yu H; Zhang H; Chen W; Maria Solé R; Aguiló M; Díaz F; Smrz M; Mocek T; Mateos X
- Abstract
We report on the optical spectroscopy and continuous-wave (CW) laser operation of ytterbium-doped yttrium gallium garnet (Yb:YGG) crystal at cryogenic temperatures. A maximum absorption cross-section of 1.7 × 10-20 cm2 with spectral bandwidth of 2.4 nm centered at 970.5 nm and a maximum emission cross-section of 6.5 × 10-20 cm2 with spectral bandwidth of 4.6 nm centered at 1024 nm were determined at 120 K. Cryogenic continuous-wave laser operation was achieved using a VBG stabilized laser diode emitting around 969 nm as pump source. At 120 K, a maximum output power of 17.50 W was achieved around 1024 nm corresponding to a slope efficiency of 87% with respect to the absorbed power.
- Published
- 2023
20. Elektro Lif Çekiminde Kullanılan Proteinler ve Yumurta Akı Esaslı Nanolif Üretimi
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Mustafa GEYSOĞLU and Funda CENGİZ ÇALLIOĞLU
- Subjects
Engineering, Chemical ,Protein ,Nanofiber ,Electrospinning ,Egg white ,Fizik, Uygulamalı ,General Medicine ,Nanolif ,Elektro lif çekim ,Yumurta akı ,Biology ,Mühendislik, Kimya ,Biyoloji ,Physics, Applied - Abstract
Bu çalışmada protein esaslı nanolifler, özellikleri ve uygulama alanları araştırılmış ve yumurta akı proteininden nanolifli yüzey üretimi gerçekleştirilmiştir. Proteinler, bitkisel ve hayvansal olmak üzere iki ana gruba ayrılırlar. Biyolojik yapıdaki bu proteinler, medikal alan başta olmak üzere gıda endüstrisinde ve kozmetik sanayiinde çeşitli kullanım alanlarına sahiptir. Bu araştırmada, protein esaslı polimerler alt sınıflara ayrılmış, her birinin özellikleri verilmiş, nanolif üretimlerinden bahsedilmiş ve protein esaslı nanoliflerin kullanım alanlarına değinilmiştir. Ayrıca yumurta akı proteini kullanılarak elektro lif çekim teknolojisi ile nanolifli yüzeyler elde edilmiştir. Protein esaslı nanoliflerin biyomedikal alanda genel olarak, ilaç salım sistemleri ve doku mühendisliğinde yapı iskelesi, yara örtüsü, doku jenerasyonu gibi alanlarda kullanımı söz konusudur. Medikal alan dışında ise biyolojik yapısından kaynaklı gıda endüstrisinde de paketleme malzemesi olarak kullanımı söz konusudur. Ayrıca, protein esaslı nanoliflerin filtre malzemesi, biyosensör, katalizör, deri protezleri, ameliyat iplikleri, yumuşak kontakt lensler gibi çok çeşitli kullanım alanları da mevcuttur., In this study, protein-based nanofibers, their properties and application areas were investigated and nanofiber surface production was carried out with egg white protein. Proteins are divided into two main groups, vegetable and animal. These biological proteins have various uses in the food industry, cosmetics industry and especially in the medical field. In this research, protein-based polymers are subclassified according to their source. The general properties of these proteins and the usage areas of protein-based nanofibers are mentioned. In addition, nanofiber surfaces were obtained with electrospinning technology using egg white protein. The protein-based nanofibers are generally used in the field of biomedicine, drug delivery systems and tissue engineering in areas such as scaffolding, wound dressing, tissue generation. Apart from the medical field, it is also used as a packaging material in the food industry due to its biological structure. In addition, protein-based nanofibers have a wide range of uses such as filter material, biosensors, catalysts, skin prostheses, surgical threads, soft contact lenses and etc.
- Published
- 2022
21. Ga4X3Mn (X = P and As)’in Manyetik ve Elektronik Özelliklerinin İncelenmesi Üzerine İlk İlkeler Çalışması
- Author
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Erkisi, Aytac
- Subjects
Antiferromagnetism ,Density functional theory ,Fizik, Uygulamalı ,Semiconductor ,Ab initio calculations ,Yarı-iletken ,Antiferromanyetizma ,ab initio hesaplamaları ,Youğunluk fonksiyonel teorisi ,General Medicine ,Physics, Applied - Abstract
In this study, the magnetic nature and also, electronic characteristics of Ga4X3Mn (X=P and As) systems, which have simple cubic structure confirming P4 ̅3m space group and 215 space number, have been reported. All calculations realized within the framework of ab initio simulation methods have been performed using the meta-generalized gradient (META-GGA) approach within the Density Functional Theory (DFT). In view of the energy-volume curves and the calculated cohesive and formation energies for considering four different types of magnetic orders, it has been detected that these compounds have A-type antiferromagnetic nature. Also, the examined electronic behaviors in the A-type antiferromagnetic order of the related systems show that all two compounds are semiconductors due to having small band gaps in their electronic band structures (Eg = 0.23 eV for Ga4P3Mn and Eg = 0.16 eV for Ga4As3Mn)., Bu çalışmada, basit kübik yapıya sahip ve P4 ̅3m uzay grubu ile 215 uzay numarasına uyan Ga4X3Mn (X=P and As) sistemlerinin manyetik doğası ve ayrıca elektronik karakteristiği rapor edilmiştir. Ab initio simülasyon yöntemleri çerçevesinde gerçekleştirilen tüm hesaplamalar, Yoğunluk Fonksiyonel Teorisi (YFT) kapsamında meta-genelleştirilmiş gradient (META-GGA) yaklaşımı kullanılarak yapılmıştır. Dört farklı tip manyetik düzen için enerji-hacim eğrileri ve hesaplanan kohesif ve oluşum enerjileri göz önüne alındığında, bu bileşiklerin A-tipi antiferromanyetik yapıya sahip oldukları tespit edilmiştir. Ayrıca ilgili sistemlerin A-tipi antiferromanyetik düzende incelenen elektronik davranışları, elektronik bant yapılarında küçük bant boşluklarına sahip olmaları nedeniyle yarı-iletken olduklarını göstermektedir (Ga4P3Mn için Eb = 0.23 eV ve Ga4As3Mn için Eb = 0.16 eV).
- Published
- 2022
22. Yarıiletken Silindirik Kuantum Noktanın Optik Özellikleri
- Author
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Arif BABANLI and Vepa SABYROV
- Subjects
Fizik, Uygulamalı ,Absorption coefficient ,Quantum dot ,Optical transitions ,General Medicine ,Soğurma katsayı ,Kuantum nokta ,Optik geçişler ,Physics, Applied - Abstract
Bu çalışmada yarıiletken silindirik kuantum noktanın optik özellikleri araştırılmıştır. Etkin kütle ve parabolik bant yaklaşımı dikkate alınarak yarıiletken silindirik kuantum noktanın enerji spektrumu ve dalga fonksiyonu köşegenleştirme yöntemiyle hesaplanmıştır. Elde ettiğimiz öz değer ve öz fonksiyon ifadelerini kullanarak alt enerji seviyeler arası optik geçişler için soğurma katsayısını hesaplamak için kullanılmıştır. Yarıiletken silindirik kuantum noktanın soğurma katsayısı gelen foton enerjisinin fonksiyonu olarak silindirin yarıçapı ve yüksekliği gibi parametrelerinin farklı değerlerine göre davranışı sayısal olarak araştırılmıştır. Ayrıca soğurma katsayı manyetik alanın farklı değerlerine göre değişimi araştırılmıştır. Elde edilen sonuçlara göre yarıiletken kuantum noktanın soğurma katsayısı manyetik alanın değişiminden bağımsız ve silindirin yarıçap ve yükseklik parametrelerinin değişimine bağlı olduğu görülmüştür., In this study, the optical properties of semiconductor cylindrical quantum dots were investigated. Considering the effective mass and parabolic band approach, the energy spectrum and wave function of the semiconductor cylindrical quantum dot are calculated using the diagonalization method. With the help of energy spectrum and wave function expressions, the expression of the absorption coefficient for the optical transitions between the lower energy levels was calculated. The absorption coefficient of the semiconductor cylindrical quantum dot we obtained, as a function of the incident photon energy, has been numerically investigated according to the different values of the radius and height parameters of the cylinder. In addition, the variation of the absorption coefficient according to different values of the magnetic field was investigated. According to the results, it has been determined that the absorption coefficient of the semiconductor quantum dot is independent of the change of the magnetic field and depends on the change of the radius and height parameters of the cylinder.
- Published
- 2022
23. Suppressing ion migration in metal halide perovskite via interstitial doping with a trace amount of multivalent cations
- Author
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Yepin Zhao, Ilhan Yavuz, Minhuan Wang, Marc H. Weber, Mingjie Xu, Joo-Hong Lee, Shaun Tan, Tianyi Huang, Dong Meng, Rui Wang, Jingjing Xue, Sung-Joon Lee, Sang-Hoon Bae, Anni Zhang, Seung-Gu Choi, Yanfeng Yin, Jin Liu, Tae-Hee Han, Yantao Shi, Hongru Ma, Wenxin Yang, Qiyu Xing, Yifan Zhou, Pengju Shi, Sisi Wang, Elizabeth Zhang, Jiming Bian, Xiaoqing Pan, Nam-Gyu Park, Jin-Wook Lee, Yang Yang, and Zhao Y., YAVUZ İ., Wang M., Weber M. H. , Xu M., Lee J., Tan S., Huang T., Meng D., Wang R., et al.
- Subjects
Kimya (çeşitli) ,Temel Bilimler (SCI) ,Physical Chemistry ,MATERIALS SCIENCE ,Kimya ,CHEMISTRY ,Materials Chemistry ,Yoğun Madde Fiziği ,General Materials Science ,Malzeme Kimyası ,Temel Bilimler ,Physics ,KİMYA, FİZİKSEL ,Metals and Alloys ,Fizikokimya ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Chemistry (miscellaneous) ,Mechanics of Materials ,Natural Sciences (SCI) ,Physical Sciences ,Engineering and Technology ,Natural Sciences ,İstatistiksel ve Doğrusal Olmayan Fizik ,FİZİK, YOĞUN MADDE ,Yüzeyler, Kaplamalar ve Filmler ,CHEMISTRY, PHYSICAL ,Fiziksel ve Teorik Kimya ,MATERIALS SCIENCE, MULTIDISCIPLINARY ,Fizik ,Metaller ve Alaşımlar ,Elektronik, Optik ve Manyetik Malzemeler ,PHYSICS, CONDENSED MATTER ,Physical and Theoretical Chemistry ,MALZEME BİLİMİ, ÇOKDİSİPLİNLİ ,Engineering, Computing & Technology (ENG) ,PHYSICS, APPLIED ,Mechanical Engineering ,Yüzeyler ve Arayüzler ,Mühendislik, Bilişim ve Teknoloji (ENG) ,Statistical and Nonlinear Physics ,General Chemistry ,Condensed Matter 1: Structural, Mechanical and Thermal Properties ,Yoğun Madde 1:Yapısal, Mekanik ve Termal Özellikler ,Genel Kimya ,Fizik Bilimleri ,FİZİK, UYGULAMALI ,Genel Malzeme Bilimi ,Mühendislik ve Teknoloji ,Malzeme Bilimi - Abstract
Cations with suitable sizes to occupy an interstitial site of perovskite crystals have been widely used to inhibit ion migration and promote the performance and stability of perovskite optoelectronics. However, such interstitial doping inevitably leads to lattice microstrain that impairs the long-range ordering and stability of the crystals, causing a sacrificial trade-off. Here, we unravel the evident influence of the valence states of the interstitial cations on their efficacy to suppress the ion migration. Incorporation of a trivalent neodymium cation (Nd3+) effectively mitigates the ion migration in the perovskite lattice with a reduced dosage (0.08%) compared to a widely used monovalent cation dopant (Na+, 0.45%). The photovoltaic performances and operational stability of the prototypical perovskite solar cells are enhanced with a trace amount of Nd3+ doping while minimizing the sacrificial trade-off.
- Published
- 2022
24. Study of Wavelet Entropy Analysis of the Fermion-like Instanton Solutions
- Author
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CANBAZ, Beyrul
- Subjects
Wavelet transform ,Phase space ,Fermion-like instanton ,Wavelet entropy ,Fizik, Uygulamalı ,General Medicine ,Dalgacık dönüşümü ,Faz uzayı ,Fermiyon benzeri instanton ,Dalgacık entropisi ,Physics, Applied - Abstract
Instantons are classical topological solutions, playing an important role in particle physics and cosmology. In this study, the periodicity of the orbits of the fermion-like instanton solutions in the two-dimensional Thirring model obtained with the Heisenberg ansatz is investigated. The trajectories of fermion-like instanton solutions are investigated by the Shannon wavelet entropy (WE) method. In addition, WE and WE spectrum in phase space are analyzed in order to have information about the characteristics of the trajectories of fermion-like instanton solutions. As a result of the study, it was seen that the fermion-like instanton solutions have regular trajectories around the stable point and irregular trajectories at other points. It was also compared with other known entropy methods (Renyi entropy and Tsallis entropy) and similar results were observed., İnstantonlar klasik topolojik çözümlerdir, parçacık fiziği ve kozmolojide önemli rol oynarlar. Bu çalışmada, Heisenberg anzatıyla elde edilen iki boyutlu Thirring modelde fermiyon benzeri instanton çözümlerinin yörüngelerinin periyodikliği incelenmiştir. Fermiyon benzeri instanton çözümlerinin yörüngeleri, Shannon dalgacık entropisi (WE) yöntemi kullanılarak incelenmektedir. Ayrıca, faz uzayında WE ve WE spektrumları, fermiyon benzeri instanton çözümlerinin yörüngelerinin karakteristiği hakkında bilgi sahibi olabilmek için analiz edilmektedir. Çalışma sonucunda, fermiyon benzeri instanton çözümlerinin kararlı nokta etrafında düzenli, diğer noktalarda ise düzensiz yörüngelere sahip olduğu görülmüştür. Ayrıca bilinen diğer entropi yöntemleriyle (Renyi entropi ve Tsallis entropi) karşılaştırılmış ve benzer sonuçlar gözlemlenmiştir.
- Published
- 2022
25. An Acoustic 3-D Positioning System for Robots Operating Underground
- Author
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Shahid Malik, Daniele Dini, Catherine O'Sullivan, Andrew Holmes, Thomas Reddyhoff, Natural Environment Research Council (NERC), and Engineering & Physical Science Research Council (EPSRC)
- Subjects
Technology ,Science & Technology ,geotechnical engineering ,underground sensing ,Physics ,Engineering, Electrical & Electronic ,sensors ,Physics, Applied ,Engineering ,Sensor applications ,Physical Sciences ,Electrical and Electronic Engineering ,buried robotics ,Instruments & Instrumentation ,Instrumentation - Abstract
Underground robots are potentially helpful in many application domains, including geotechnical engineering, agriculture, and archaeology. One of the critical challenges in developing underground robotics is the accurate estimation of the positions of the robots. Acoustic-based positioning systems have been explored for developing an underground 3D positioning system. However, the positioning range is limited due to attenuation in the medium. This letter proposes an underground positioning system that utilizes a novel and easy-to-implement electronic approach for measuring the acoustic propagation times between multiple transmitters and a receiver. We demonstrate a prototype using four transmitters at the surface and a single buried acoustic sensor as a proof-of-concept. The times of arrival for signals emitted by the different sources are measured by correlating the transmitted and received signals. The distances between the multiple transmitters and a receiver are estimated, and a tri-linearization algorithm is used to estimate the position of the buried sensor in 3D with respect to reference coordinates. The system is tested in a soil tank. The experimental results show that the proposed system is able to estimate the 3D position of buried sensors with an error of less than ±2.5 cm within a measurement field of size 50 cm × 50 cm × 35 cm in X, Y, and Z (width × length × depth). The proposed electronic synchronization approach allows increasing the positioning range of the system by increasing the number of transmitters at the surface. This paves the way for the development of a positioning system for robots operating underground.
- Published
- 2022
26. Quantum Dot to Nanorod Transition for Efficient White-Light-Emitting Diodes with Suppressed Absorption Losses
- Author
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Asim Onal, Sadra Sadeghi, Rustamzhon Melikov, Onuralp Karatum, Guncem Ozgun Eren, Sedat Nizamoglu, Önal, Asım, Sadeghi, Sadra, Karatum, Onuralp, Nizamoğlu, Sedat (ORCID 0000-0003-0394-5790 & YÖK ID 130295), Eren, Güncem Özgün, Melikov, Rustamzhon, College of Engineering, Graduate School of Sciences and Engineering, Department of Materials Science and Engineering, Department of Electrical and Electronics Engineering, and Department of Biomedical Sciences and Engineering
- Subjects
Quantum dots ,Nanorods ,External quantum efficiency ,Light-emitting diodes ,Liquid ,Luminous efficiency ,Electrical and Electronic Engineering ,Nanoscience and nanotechnology ,Materials science, multidisciplinary ,Optics ,Physics, applied ,Physics, condensed matter ,Atomic and Molecular Physics, and Optics ,Biotechnology ,Electronic, Optical and Magnetic Materials - Abstract
Colloidal nanocrystals have great potential for next-generation solid-state lighting due to their outstanding emission and absorption tunability via size and morphology, narrow emission linewidth, and high photoluminescence quantum yield (PLQY). However, the losses due to self-and interabsorption among multitudes of nanocrystals significantly decrease external quantum yield levels of light-emitting diodes (LEDs). Here, we demonstrate efficient white LEDs via CdSe/CdS dot to ""dot-in-rod"" transition that enabled a large Stokes shift of 780 meV and significantly reduced absorption losses when used in conjunction with near-unity PLQY ZnCdSe/ZnSe quantum dots (QDs) emitting at the green spectral range. The optimized incorporation of nanocrystals in a liquid state led to the white LEDs with an ultimate external quantum efficiency (EQE) of 42.9%, with a net increase of EQE of 10.3% in comparison with white LEDs using CdSe/CdS dots. Therefore, combinations of nanocrystals with different nanomorphologies hold high promise for efficient white LEDs., Scientific and Technological Research Council of Turkey (TÜBİTAK); Turkish Academy of Sciences (TU?BA-GEBIP; The Young Scientist Award Program)
- Published
- 2022
27. How to GIWAXS: Grazing Incidence Wide Angle X-Ray Scattering Applied to Metal Halide Perovskite Thin Films
- Author
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Steele, Julian A, Solano, Eduardo, Hardy, David, Dayton, Damara, Ladd, Dylan, White, Keith, Chen, Peng, Hou, Jingwei, Huang, Haowei, Saha, Rafikul Ali, Wang, Lianzhou, Gao, Feng, Hofkens, Johan, Roeffaers, Maarten BJ, Chernyshov, Dmitry, and Toney, Michael F
- Subjects
Technology ,SOLAR-CELLS ,Science & Technology ,Energy & Fuels ,POWDER DIFFRACTION ,SURFACE ,Chemistry, Physical ,Physics ,Materials Science ,CHARGE-CARRIER DYNAMICS ,HYBRID PEROVSKITES ,synchrotron science ,Materials Science, Multidisciplinary ,RUDDLESDEN-POPPER ,perovskite solar cells ,Physics, Applied ,Chemistry ,Physics, Condensed Matter ,thin films ,Physical Sciences ,FAILURE MECHANISMS ,CRYSTAL-STRUCTURES ,PHASE-TRANSITIONS ,VERTICAL ORIENTATION ,GIWAXS - Abstract
ispartof: ADVANCED ENERGY MATERIALS status: Published online
- Published
- 2023
28. Strong Polarization Dependent Nonlinear Excitation of a Perovskite Nanocrystal Monolayer on a Chiral Dielectric Nanoantenna Array
- Author
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Ilka Vinçon, Fedja J. Wendisch, Daniele De Gregorio, Stefanie D. Pritzl, Quinten A. Akkerman, Haoran Ren, Leonardo de S. Menezes, Stefan A. Maier, and Jochen Feldmann
- Subjects
Technology ,Materials Science ,0205 Optical Physics ,chirality ,Materials Science, Multidisciplinary ,QUANTUM DOTS ,Physics, Applied ,ENHANCEMENT ,ABSORPTION ,Nanoscience & Nanotechnology ,Electrical and Electronic Engineering ,0206 Quantum Physics ,perovskite ,Science & Technology ,Physics ,Optics ,chiral nanoantenna ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,0906 Electrical and Electronic Engineering ,SIZE ,Physics, Condensed Matter ,polarization dependent excitation ,dielectric metasurface ,Physical Sciences ,Science & Technology - Other Topics ,two-photon excited photoluminescence ,EMISSION ,Biotechnology - Abstract
With their unique optoelectronic properties, perovskite nanocrystals are highly advantageous semiconductor materials for tailored light applications including an interaction with circularly polarized light. Although chiral perovskite nanocrystals have been obtained by the adsorption of chiral molecules, their chiroptical response is still intrinsically weak. Alternatively, perovskites have been combined with artificial chiral surfaces demonstrating enhanced chiroptical responses. However, bulk perovskite films of considerable thickness were required, mitigating the perovskite’s photoluminescence efficiency and processability. Here we developed a hybrid system of a dielectric chiral nanoantenna array that was coated with a monolayer of cubic all-inorganic lead halide perovskite nanocrystals. By tuning the thickness of the perovskite film down to one monolayer of nanocrystals, we restricted the interactions exclusively to the near-field regime. The chiral surface built of z-shaped Si nanoantennas features pronounced chiral resonances in the visible to IR region. We demonstrate that the two-photon excited photoluminescence emission of the nanocrystals can be enhanced by up to one order of magnitude in this configuration. This emission increase is controllable by the choice of the excitation wavelength and polarization with an asymmetry in emission of up to 25% upon left and right circularly polarized illumination. Altogether, our findings demonstrate a pathway to an all-optical control and modulation of perovskite light emission via strong polarization sensitive light–matter interactions in the near-field, rendering this hybrid system interesting for sensing and display technologies.
- Published
- 2022
29. Plasmonic MIM and MSM Waveguide Couplers for Plasmonic Integrated Computing System
- Author
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Samantha Lubaba Noor, Pol Van Dorpe, Dennis Lin, Francky Catthoor, and Azad Naeemi
- Subjects
Plasmons ,Technology ,DEVICES ,FABRICATION ,FINITE ,Physics, Applied ,Claddings ,MIM waveguide ,Engineering ,Energy per bit ,DESIGN ,power transmission ,waveguide coupling ,Electrical and Electronic Engineering ,SILICON ,Couplers ,plasmon detec- tor ,Science & Technology ,Physics ,Engineering, Electrical & Electronic ,Optics ,Detectors ,TRANSPORT ,Atomic and Molecular Physics, and Optics ,Photonics ,Physical Sciences ,Couplings ,Performance evaluation ,MODES - Abstract
ispartof: IEEE PHOTONICS JOURNAL vol:14 issue:4 status: published
- Published
- 2022
30. Ab initio Yöntemler ile Ni2ScAl Bileşiğinin Mekanik ve Termodinamik Özelliklerinin İncelenmesi
- Author
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Tahsin ÖZER and Nihat ARIKAN
- Subjects
Ni2ScAl,Heusler,Elastik sabitler,Termodinamik ,Fizik, Uygulamalı ,General Medicine ,Ni2ScAl,Heusler,Elastic constant,Thermodynamic ,Physics, Applied - Abstract
In this study, the mechanical and thermodynamic properties of Ni2ScAl full Heusler compound were investigated. For this purpose, first structural optimization was made, and then elastic constants were calculated. Since the calculated elastic constants meet the stability criteria, the elastic modulus was calculated, and its anisotropy was examined. Debye temperature, Gruneisen constant and thermal conductivities were estimated. As a result of the calculations, it is expected that the Ni2ScAl compound is not hard but will show anisotropic and ductile properties. It can be used as a thermal insulator due to its small minimum thermal conductivity., Çalışmada Ni2ScAl full Heusler bileşiğinin mekanik ve termodinamik özellikleri araştırılmıştır. Bu amaçla, önce yapısal optimizasyon yapılmış akabinde elastik sabitler hesaplanmıştır. Hesaplanan elastik sabitlerin kararlılık kriterlerini sağladığından dolayı elastik modülü hesaplanmış ve anizotropisi incelenmiştir. Debye sıcaklığı, Gruneisen sabiti ve termal iletkenlikleri tahmin edilmiştir. Yapılan hesaplamalar sonucunda Ni2ScAl bileşiği sert olmayıp, anizotrop ve sünek özellik göstermesi beklenmektedir. Küçük minimum termal iletkenliğe sahip olmasından dolayı, ısıl yalıtkan olarak kullanılabilir.
- Published
- 2022
31. Theoretical Investigation of Some Radiation Shielding Parameters of Radiodiagnostic Agents
- Author
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Yusuf KAVUN and Eyyup TEL
- Subjects
Phy-X software,Radiation shielding,Gadoxetic acid,Dadopentetic acid,Fluorescein ,Phy-X yazılımı,Radyasyon zırhlama,Gadoxetic asit ,Fizik, Uygulamalı ,General Medicine ,Physics, Applied - Abstract
Tıbbi görüntülemenin sağlık hizmetlerindeki etkisi her geçen gün artmaktadır. Bu sayede hastalıklar daha erken teşhis edilebilir ve tedaviler daha etkin bir şekilde yürütülebilir. Tıbbi görüntülemenin kullanımı teşhisin ötesine geçerek hastalık önleme ve tedavi alanlarına ulaştığından, küresel ölçekte sağlık hizmetlerinin maliyetleri de önemli ölçüde azalmaktadır. Bu çalışmada, görüntülemede kullanılan C23H30GdN3O11 (Gadoxetic asit), C28H54GdN5O20 (Gadopentetik asit) ve C20H12O5 (Fluorescein) gibi ilaçların radyasyon koruyucu özellikleri araştırılmıştır. Bu radyasyon parametreleri, lineer ve kütle zayıflama katsayılarını (LAC, MAC), yarım ve onuncu değer katmanlarını (HVL, TVL), ortalama serbest yolu (MFP), etkin atom numarası ve elektron yoğunluğunu (Zeff, Neff) ve etkin iletkenliği (Ceff) içerir. Phy-X yazılımını kullanarak enerji. Bu veriler 1 keV ile 2 MeV enerji bölgesi aralığı için üretilmiştir. Elde edilen verilere göre bu enerji değerinden sonra 100 keV'a kadar saçılan verilerin birbiriyle uyumlu olduğu görülmüştür., The impact of medical imaging in health services is increasing day by day. In this way, diseases can be diagnosed earlier and treatments can be carried out more effectively. As the use of medical imaging goes beyond diagnosis and reaches the areas of disease prevention and treatment, the costs of healthcare services on a global scale are also significantly reduced. In this study, radiation shielding properties of drugs such as C23H30GdN3O11 (Gadoxetic acid), C28H54GdN5O20 (Gadopentetic acid) and C20H12O5 (Fluorescein) used in imaging have been investigated. These radiation parameters include linear and mass attenuation coefficients (LAC, MAC), half and tenth value layers (HVL, TVL), mean free path (MFP), effective atomic number and electron density (Zeff, Neff) and effective conductivity (Ceff) energy by using Phy-X software. These data have been generated for 1 keV to 2 MeV energy region. According to the data obtained, it was seen that the data scattered up to 100 keV were compatible with each other after this energy value.
- Published
- 2022
32. Quantification of Protein Glycosylation Using Nanopores
- Author
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Roderick Corstiaan Abraham Versloot, Florian Leonardus Rudolfus Lucas, Liubov Yakovlieva, Matthijs Jonathan Tadema, Yurui Zhang, Thomas M. Wood, Nathaniel I. Martin, Siewert J. Marrink, Marthe T. C. Walvoort, Giovanni Maglia, Chemical Biology 1, Chemical Biology 2, and Molecular Dynamics
- Subjects
Technology ,Glycosylation ,Chemistry, Multidisciplinary ,Materials Science ,Bioengineering ,Materials Science, Multidisciplinary ,single molecule ,UBIQUITIN ,Physics, Applied ,Nanopores ,proteomics ,protein glycosylation ,MOLECULE MASS-SPECTROMETRY ,rhamnosylation ,Nanotechnology ,General Materials Science ,nanopore spectrometry ,Nanoscience & Nanotechnology ,Science & Technology ,Chemistry, Physical ,Mechanical Engineering ,Physics ,Proteins ,PEPTIDES ,General Chemistry ,Condensed Matter Physics ,challenges protein glycosylation ,Chemistry ,Physics, Condensed Matter ,DISCRIMINATION ,Physical Sciences ,Science & Technology - Other Topics ,Peptides - Abstract
Although nanopores can be used for single-molecule sequencing of nucleic acids using low-cost portable devices, the characterization of proteins and their modifications has yet to be established. Here, we show that hydrophilic or glycosylated peptides translocate too quickly across FraC nanopores to be recognized. However, high ionic strengths (i.e., 3 M LiCl) and low pH (i.e., pH 3) together with using a nanopore with a phenylalanine at its constriction allows the recognition of hydrophilic peptides, and to distinguish between mono- and diglycosylated peptides. Using these conditions, we devise a nanopore method to detect, characterize, and quantify post-translational modifications in generic proteins, which is one of the pressing challenges in proteomic analysis. ispartof: NANO LETTERS vol:22 issue:13 pages:5357-5364 ispartof: location:United States status: published
- Published
- 2022
33. Review of Optoelectronic Properties of ZnO Photodetector
- Author
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Kishwar Mohammed WASMAN and Bestoon HAMADAMEEN
- Subjects
Fizik, Uygulamalı ,ZnO,Photodetectors,Optoelectrical ,Physics, Applied - Abstract
Photodetection has been gained a lot of attention in last years biased on military wide range and civil application. With essential properties of Zno which has the wide band gap, strong radiation hardness, low cost and good chemical stabilities. ZnO are considered as the most successful candidate for UV photodetector. The study of our report is to review photodetectors based on doped Zno nanostructures and the new advances in ZnO nanostructured generation technique including adjustment and doping methods with modifications of ZnO photodetector. Final part of this review is about literature reviews were reported in recent years about optoelectrical property of Zno nanostructures, due to the fact that Zinc oxide is an important semiconductor material for optoelectronic and industrial applications, such solar cell, photosensors and photodetectors.
- Published
- 2022
34. Review on Surface Texturing Method for Solar Cell Efficiency Enhancement
- Author
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Razaw Dindar HUSSEİN and Dilshad ISMAEL
- Subjects
Fizik, Uygulamalı ,Solar Cell,efficiency,surface texturing,Photovoltaic ,Physics, Applied - Abstract
Sun oriented cell are also known as Photoelectric (PE) cells, which labor to transform sunlight specifically into electricity, Photoelectric cells are attached electric powered and conveniently arranged within a wide outline known as a sun based board. The efficiency of the sun powered cell is turns on the number of consume photons which are absorbed in the consumer sheet of sun powered cell. However, the low absorption rate of the absorber material and light reflection in the surface of material and the material interfaces of the glass absorbers will reduce the conversion of solar energy. The effect of the energy conversion can be upgrade by modifying the surface morphology of the solar cell. In this article review of Exterior by different Texturing Method to increase efficiency enhancement, minimum waste energy of light of the sun and to get a maximum efficiency for the Sun Powered Cell Effective Upgrade has been investigated.
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- 2022
35. A review on Physical Properties of CdS Thin Film
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Razaw Dindar HUSSEİN and Adeeb JAFİR
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Cds thin film,properties of Cds,deposition of Cds ,Fizik, Uygulamalı ,Physics, Applied - Abstract
CdS Cadmium Sulfide is the important semiconductor materials. Semiconductors are solids with conductivities ranged from 104 to 10-10 (n cm)-l. The properties of CdS are structural, Electrical and Optical. We examine a number of papers published between 1983 and 2015 that created CdS thin films in a variety of ways, including chemical bath deposition, spray pyrolysis, thermal evaporation, close spaced sublimation, and pulsed laser ablation. They found band gap energy in (eV), Refractive index (n) and Extension coefficient (k). X-ray diffraction, the researchers employed energy dispersive X-ray spectroscopy with scanning electron microscopy in this study. The crystallinity the quality of the movie improves after annealing, As a result, optical transmittance is reduced. The structure is hexagonal in general. All of the films are ideal as efficient for solar cell applications, there are a number of different window layers that may be used. Due to their high transmittance and low resistance values. These findings suggest that CBD films with a broad Low resistivity, high mobility, and a high carrier concentration are all characteristics of the band gap. Produced at pH 11 are ideal contenders for use in various optoelectronic devices.
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- 2022
36. The Determination of Eigenvalues and Eigenvectors of the Orbital Angular Momentum
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Kishwar Mohammed WASMAN and Saman MAWLUD
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Fizik, Uygulamalı ,Orbital angular momentum,Quantization,Raising and lowering operators,Quantum numbers,Matrix and graphical representation ,Physics, Applied - Abstract
The theory of angular momentum performance a significant position in the classical and quantum mechanical study of physical properties, such as studies into nuclear, atomic, and molecular processes, as well as other quantum problems, including spherical symmetry. In this analysis, angular momentum operators are described in multiple ways, based on the angular momentum operator's commutator, matrix, and geometric representation, The eigenvalue and eigenvector were also known for operatorsJ ̂_±,J ⃑ ̂^2, J ̂_x,J ̂_y and J ̂_zwithin the |j,┤ ├ m⟩ basis. Furthermore, in quantum mechanics, angular momentum is called quantized variable, meaning that it comes in discrete quantities. In contrast to the macroscopic system case where a continuous variable is angular momentum.
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- 2022
37. A Hydrophobic Antireflective and Antidust Coating With SiO2 and TiO2 Nanoparticles Using a New 3-D Printing Method for Photovoltaic Panels
- Author
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Nazmi Ekren, Ali Samet Sarkin, Safak Saglam, and Ekren N., Sarkin A. S., Sağlam Ş.
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Tarımsal Bilimler ,Printers ,Genel Enerji ,Surface treatment ,Mühendislik ,Temel Bilimler (SCI) ,Enerji Mühendisliği ve Güç Teknolojisi ,ENGINEERING ,MATERIALS SCIENCE ,Ziraat ,antireflection ,ENERGY & FUELS ,Materials Chemistry ,General Materials Science ,Enerji (çeşitli) ,3-D printing ,Malzeme Kimyası ,Agricultural Sciences ,Temel Bilimler ,Physics ,nanoparticle ,ENERJİ VE YAKITLAR ,Metals and Alloys ,General Engineering ,Tarımda Enerji ,Agriculture ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Energy in Agriculture ,Fuel Technology ,General Energy ,Natural Sciences (SCI) ,Physical Sciences ,Engineering and Technology ,Printing ,Biofuels Technology ,Natural Sciences ,İstatistiksel ve Doğrusal Olmayan Fizik ,self-cleaning ,Programmable logic arrays ,Farm Machinery ,Mühendislik (çeşitli) ,FABRICATION ,Energy Engineering and Power Technology ,MATERIALS SCIENCE, MULTIDISCIPLINARY ,Fizik ,photovoltaic (PV) ,Metaller ve Alaşımlar ,Biyoyakıt Teknolojisi ,Genel Mühendislik ,Coatings ,Tarım Makineleri ,hydrophobic ,Electrical and Electronic Engineering ,MALZEME BİLİMİ, ÇOKDİSİPLİNLİ ,Engineering, Computing & Technology (ENG) ,PHYSICS, APPLIED ,Engineering (miscellaneous) ,Yenilenebilir Enerji, Sürdürülebilirlik ve Çevre ,SOL-GEL ,Renewable Energy, Sustainability and the Environment ,Yakıt Teknolojisi ,SURFACES ,Mühendislik, Bilişim ve Teknoloji (ENG) ,Statistical and Nonlinear Physics ,TRANSPARENT ,Fizik Bilimleri ,FİZİK, UYGULAMALI ,Genel Malzeme Bilimi ,Solvents ,Mühendislik ve Teknoloji ,Glass ,POLYMERS ,Malzeme Bilimi ,Energy (miscellaneous) - Abstract
The main outdoor factors that reduce the efficiency of the photovoltaic (PV) panel are the reflection and refraction of light, dirt, dust, and organic waste accumulating on the panel surface. In this article, an antireflection, self-cleaning coating was applied on the PV panel cover glass with a new method. With the coating, the surface has been given a hydrophobic feature. As a coating method, a 3-D printer has not been seen in the literature and used as a new method. The electrospinning method has also been tried as an alternative method. Solutions in different combinations were developed using polylactic acid or polymethylmethacrylate polymer, chloroform ($\text{CHCl}_3$) as a solvent, and silicon dioxide ($\text{SiO}_2$) and titanium dioxide ($\text{TiO}_2$) nanoparticles as primary materials in a modified 3-D printer for bioprinting. Five PV panels were obtained by applying different 3-D parameters from three solutions, which have the best results. Coating thicknesses are in the range of 3.12-8.47 mu m. Coated and uncoated PV panels were tested in outdoor conditions for ten-day periods. The power outputs of the PV panels were measured, and their ten-day average efficiency was presented. According to the results, the highest efficiency increase is 8.7%. The highest light transmittance is 88.2% at 550 nm. In addition, hydrophobic properties were observed on all surfaces and the water contact angle was measured as 96.18 degrees.
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- 2022
38. A review on atom probe and correlative microscopy studies of corrosion in nickel-based superalloys
- Author
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C. Rodenkirchen, M. Appleton, M. P. Ryan, S. Pedrazzini, Rolls-Royce Plc, and Engineering & Physical Science Research Council (EPSRC)
- Subjects
Technology ,Science & Technology ,Physics ,SINGLE-CRYSTAL SUPERALLOY ,Materials Science ,Materials Science, Multidisciplinary ,0303 Macromolecular and Materials Chemistry ,OXIDATION ,Condensed Matter Physics ,BORON ,Physics, Applied ,TOMOGRAPHY ,CRACK ,Physical Sciences ,OXIDE SCALE FORMATION ,GROWTH ,General Materials Science ,Physical and Theoretical Chemistry ,0912 Materials Engineering ,Applied Physics ,0913 Mechanical Engineering - Abstract
This article discusses challenges faced in the development of new Ni-based superalloys for applications in the hottest sections of turbine engines and the use of atom probe tomography and correlative microscopy for characterization of these complex alloys with regards to microstructural and compositional design. The two strengthening phases γ and γ′ are introduced and the precipitation of topologically close-packed phases and their potential detrimental effects on superalloy properties are reviewed. Mechanisms of environmental degradation, namely oxidation and hot corrosion, are elucidated and recent research studies on a new phenomenon of hot corrosion at relatively low temperatures below 600°C are discussed. The effect of individual alloying elements on superalloy properties is reviewed, with a focus on Mo and W. The use of atom probe in correlation with state-of-the-art microscopy, spectroscopy and diffraction techniques to study and understand oxidation and corrosion of Ni-based superalloys, including crack tip investigations, is presented.Graphical abstract
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- 2022
39. GUP-corrected ΛCDM cosmology
- Author
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Salih Kibaroğlu, Maltepe Üniversitesi, Mühendislik ve Doğa Bilimleri Fakültesi, and Kibaroğlu, Salih
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uncertainty principle ,generalized gravity theories,cosmology,uncertainty principle ,Fizik, Uygulamalı ,General Engineering ,generalized gravity theories ,cosmology ,Physics, Applied - Abstract
In this study, we investigate the effect of the generalized uncertainty principle on the ΛCDM cosmological model. Using quantum corrected Unruh effect and Verlinde’s entropic gravity idea, we find Planck-scale corrected Friedmann equations with a cosmological constant. These results modify the ΛCDM cosmology.
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- 2022
40. Predicting Adherence to Home-Based Cardiac Rehabilitation with Data-Driven Methods
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Dimitris Filos, Jomme Claes, Véronique Cornelissen, Evangelia Kouidi, and Ioanna Chouvarda
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Technology ,IMPACT ,Chemistry, Multidisciplinary ,Materials Science ,Engineering, Multidisciplinary ,Materials Science, Multidisciplinary ,Physics, Applied ,Engineering ,adherence ,cardiac rehabilitation ,machine learning ,prediction ,exercise ,home-based ,familiarization phase ,telemonitoring ,General Materials Science ,Instrumentation ,Fluid Flow and Transfer Processes ,RISK ,Science & Technology ,Process Chemistry and Technology ,Physics ,General Engineering ,EFFICACY ,EUROPEAN-SOCIETY ,Computer Science Applications ,Chemistry ,Physical Sciences ,CORONARY-ARTERY-DISEASE ,HEART ,EXERCISE PROGRAMS ,LIFE-STYLE ,INTERVENTION - Abstract
Cardiac rehabilitation (CR) focuses on the improvement of health or the prevention of further disease progression after an event. Despite the documented benefits of CR programs, the participation remains suboptimal. Home-based CR programs have been proposed to improve uptake and adherence. The goal of this study was to apply an end-to-end methodology including machine learning techniques to predict the 6-month adherence of cardiovascular disease (CVD) patients to a home-based telemonitoring CR program, combining patients’ clinical information with their actual program participation during a short familiarization phase. Fifty CVD patients participated in such a program for 6 months, enabling personalized guidance during a phase III CR study. Clinical, fitness, and psychological data were measured at baseline, whereas actual adherence, in terms of weekly exercise session duration and patient heart rate, was measured using wearables. Hierarchical clustering was used to identify different groups based on (1) patients’ clinical baseline characteristics, (2) exercise adherence during the familiarization phase, and (3) the whole program adherence, whereas the output of the clustering was determined using repetitive decision trees (DTs) and random forest (RF) techniques to predict long-term adherence. Finally, for each cluster of patients, network analysis was applied to discover correlations of their characteristics that link to adherence. Based on baseline characteristics, patients were clustered into three groups, with differences in behavior and risk factors, whereas adherent, non-adherent, and transient adherent patients were identified during the familiarization phase. Regarding the prediction of long-term adherence, the most common DT showed higher performance compared with RF (precision: 80.2 ± 19.5% and 71.8 ± 25.8%, recall: 94.5 ± 14.5% and 71.8 ± 25.8% for DT and RF accordingly). The analysis of the DT rules and the analysis of the feature importance of the RF model highlighted the significance of non-adherence during the familiarization phase, as well as that of the baseline characteristics to predict future adherence. Network analysis revealed different relationships in different clusters of patients and the interplay between their behavioral characteristics. In conclusion, the main novelty of this study is the application of machine learning techniques combining patient characteristics before the start of the home-based CR programs with data during a short familiarization phase, which can predict long-term adherence with high accuracy. The data used in this study are available through connected health technologies and standard measurements in CR; thus, the proposed methodology can be generalized to other telerehabilitation programs and help healthcare providers to improve patient-tailored enrolment strategies and resource allocation.
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- 2023
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41. Synthesis and Characterization of Gold Chiral Nanoparticles Functionalized by a Chiral Drug
- Author
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Simona Bettini, Michela Ottolini, Donato Valli, Rosanna Pagano, Chiara Ingrosso, Maarten Roeffaers, Johan Hofkens, Ludovico Valli, and Gabriele Giancane
- Subjects
Technology ,Science & Technology ,chiral nanostructures ,SURFACE ,SERS ,General Chemical Engineering ,Chemistry, Multidisciplinary ,Physics ,Materials Science ,D-penicillamine ,Materials Science, Multidisciplinary ,Physics, Applied ,circular dichroism ,Chemistry ,spectroscopic characterization ,DESIGN ,gold nanoparticles ,Physical Sciences ,Science & Technology - Other Topics ,General Materials Science ,Nanoscience & Nanotechnology - Abstract
Inorganic chiral nanoparticles are attracting more and more attention due to their peculiar optical properties and potential biological applications, such as bioimaging, therapeutics, and diagnostics. Among inorganic chiral nanoparticles, gold chiral nanostructures were demonstrated to be very interesting in this context, with good physical chemical stability and also the possibility to decorate the surface, improving biomedical application as the interaction with the bio-systems. Gold (Au) nanostructures were synthesized according to a seed-mediated procedure which envisages the use of cetyltrimethylammonium bromide (CTAB) as the capping agent and L- and D-cysteine to promote chirality. Au nanostructures have been demonstrated to have opposite circular dichroism signals depending on the amino acid enantiomer used during the synthesis. Then, a procedure to decorate the Au surface with penicillamine, a drug used for the treatment of Wilson's disease, was developed. The composite material of gold nanoparticles/penicillamine was characterized using electron microscopy, and the penicillamine functionalization was monitored by means of UV-Visible, Raman, and infrared spectroscopy, highlighting the formation of the Au-S bond. Furthermore, electron circular dichroism was used to monitor the chirality of the synthesized nanostructures and it was demonstrated that both penicillamine enantiomers can be successfully bonded with both the enantiomers of the gold nanostructures without affecting gold nanoparticles' chirality. The effective modification of nanostructures' surfaces via penicillamine introduction allowed us to address the important issue of controlling chirality and surface properties in the chiral nano-system. ispartof: NANOMATERIALS vol:13 issue:9 ispartof: location:Switzerland status: published
- Published
- 2023
42. Unconventional Giant 'Magnetoresistance' in Bosonic Semiconducting Diamond Nanorings
- Author
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Gufei Zhang, Ramiz Zulkharnay, Xiaoxing Ke, Meiyong Liao, Liwang Liu, Yujie Guo, Yejun Li, Horst‐Günter Rubahn, Victor V. Moshchalkov, and Paul W. May
- Subjects
Technology ,ZR ,Chemistry, Multidisciplinary ,T-C ,Materials Science ,Materials Science, Multidisciplinary ,diamond nanowires ,Physics, Applied ,bosonic semiconductors ,General Materials Science ,Nanoscience & Nanotechnology ,PSEUDOGAP ,TRANSITION-TEMPERATURE ,Science & Technology ,Chemistry, Physical ,ORIGIN ,Physics ,SUPERCONDUCTIVITY ,Mechanical Engineering ,GAP ,unconventional giant magnetoresistance ,Chemistry ,Physics, Condensed Matter ,Mechanics of Materials ,Physical Sciences ,Science & Technology - Other Topics ,trapping of Cooper pairs ,diamond nanorings ,RESISTANCE PEAK - Abstract
The emergence of superconductivity in doped insulators such as cuprates and pnictides coincides with their doping-driven insulator-metal transitions. Above the critical doping threshold, a metallic state sets in at high temperatures, while superconductivity sets in at low temperatures. An unanswered question is whether the formation of Cooper pairsin a well-established metal will inevitably transform the host material into a superconductor, as manifested by a resistance drop. Here, this question is addressed by investigating the electrical transport in nanoscale rings (full loops) and half loops manufactured from heavily boron-doped diamond. It is shown that in contrast to the diamond half-loops (DHLs) exhibiting a metal-superconductor transition, the diamond nanorings (DNRs) demonstrate a sharp resistance increase up to 430% and a giant negative "magnetoresistance" below the superconducting transition temperature of the starting material. The finding of the unconventional giant negative "magnetoresistance", as distinct from existing categories of magnetoresistance, that is, the conventional giant magnetoresistance in magnetic multilayers, the colossal magnetoresistance in perovskites, and the geometric magnetoresistance in semiconductor-metal hybrids, reveals the transformation of the DNRs from metals to bosonic semiconductors upon the formation of Cooper pairs. DNRs like these could be used to manipulate Cooper pairs in superconducting quantum devices. ispartof: ADVANCED MATERIALS vol:35 issue:22 ispartof: location:Germany status: Published online
- Published
- 2023
43. Understanding the phase transition mechanism in the lead halide perovskite CsPbBr3 via theoretical and experimental GIWAXS and Raman spectroscopy
- Author
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Hoffman, Alexander, Saha, Rafikul Ali, Borgmans, Sander, Puech, Pascal, Braeckevelt, Tom, Roeffaers, Maarten B. J., Steele, Julian A. A., Hofkens, Johan, and Van Speybroeck, Veronique
- Subjects
DISORDER ,Technology ,Technology and Engineering ,Science & Technology ,IODIDE PEROVSKITES ,Physics ,TOTAL-ENERGY CALCULATIONS ,Materials Science ,Materials Science, Multidisciplinary ,PHONON ,FLUCTUATIONS ,Physics, Applied ,MOLECULAR-DYNAMICS ,Physical Sciences ,Science & Technology - Other Topics ,MODE ,Nanoscience & Nanotechnology ,TEMPERATURE ,BREAKING - Abstract
Metal-halide perovskites (MHPs) exhibit excellent properties for application in optoelectronic devices. The bottleneck for their incorporation is the lack of long-term stability such as degradation due to external conditions (heat, light, oxygen, moisture, and mechanical stress), but the occurrence of phase transitions also affects their performance. Structural phase transitions are often influenced by phonon modes. Hence, an insight into both the structure and lattice dynamics is vital to assess the potential of MHPs. In this study, GIWAXS and Raman spectroscopy are applied, supported by density functional theory calculations, to investigate the apparent manifestation of structural phase transitions in the MHP CsPbBr3. Macroscopically, CsPbBr3 undergoes phase transitions between a cubic (alpha), tetragonal (beta), and orthorhombic (gamma) phase with decreasing temperature. However, microscopically, it has been argued that only the ? phase exists, while the other phases exist as averages over length and time scales within distinct temperature ranges. Here, direct proof is provided for this conjecture by analyzing both theoretical diffraction patterns and the evolution of the tilting angle of the PbBr6 octahedra from molecular dynamics simulations. Moreover, sound agreement between experimental and theoretical Raman spectra allowed to identify the Raman active phonon modes and to investigate their frequency as a function of temperature. As such, this work increases the understanding of the structure and lattice dynamics of CsPbBr3 and similar MHPs.
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- 2023
44. Machining strategy determination for single- and multi-material wire and arc additive manufactured thin-walled parts
- Author
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Ozan Can Ozaner, Damjan Klobčar, and Abhay Sharma
- Subjects
machinability ,Technology ,WAAM ,mehanska obdelava ,Materials Science ,specifična rezalna energija ,Materials Science, Multidisciplinary ,bimetali ,SURFACE-ROUGHNESS ,PARAMETERS ,Physics, Applied ,General Materials Science ,specific cutting energy ,aditivne tehnologije ,Science & Technology ,Chemistry, Physical ,Physics ,integriteta površin ,udc:621.7+621.9 ,surface integrity ,Chemistry ,Physics, Condensed Matter ,bimetallic ,Physical Sciences ,Metallurgy & Metallurgical Engineering ,METALS ,oblikovno obločno navarjanje ,additive manufacturing - Abstract
Wire and arc additive manufacturing (WAAM) technology has recently become attractive due to the fact of its high production capacity and flexible deposition strategy. One of the most prominent drawbacks of WAAM is surface irregularity. Therefore, WAAMed parts cannot be used as built; they require secondary machining operations. However, performing such operations is challenging due to the fact of high waviness. Selecting an appropriate cutting strategy is also challenging, because surface irregularity makes cutting forces unstable. The present research determines the most suitable machining strategy by assessing the specific cutting energy and local machined volume. Up- and down-milling are evaluated by calculating the removed volume and specific cutting energy for creep-resistant steel, stainless steel, and their combination. It is shown that the main factors that affect the machinability of WAAMed parts are the machined volume and specific cutting energy rather than the axial and radial depths of the cut due to the fact of high surface irregularity. Even though the results were unstable, a surface roughness of 0.1 µm was obtained with up-milling. Despite a two-fold difference in the hardness between the two materials in the multi-material deposition, it is found that hardness should not be used as a criterion for as-built surface processing. In addition, the results show no machinability difference between multi- and single-material components for a low machined volume and low surface irregularity. ispartof: MATERIALS vol:16 issue:5 ispartof: location:Switzerland status: published
- Published
- 2023
45. Performance analysis of a pemfc-based grid-connected distributed generation system
- Author
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Erkan Dursun, Alper Nabi AKPOLAT, Yongheng Yang, and AKPOLAT A. N., DURSUN E., Yang Y.
- Subjects
Alkoloidler ,Kimya (çeşitli) ,Temel Bilimler (SCI) ,Mühendislik ,ENGINEERING ,KİMYA, MULTİDİSİPLİNER ,Biochemistry ,MATERIALS SCIENCE ,Kimya ,wind turbine ,CHEMISTRY ,Biyokimya ,Materials Chemistry ,General Materials Science ,Instrumentation ,Fluid Flow and Transfer Processes ,Malzeme Kimyası ,Temel Bilimler ,Physics ,Metals and Alloys ,General Engineering ,Harita Mühendisliği-Geomatik ,Computer Science Applications ,Chemistry (miscellaneous) ,Natural Sciences (SCI) ,Physical Sciences ,Engineering and Technology ,Natural Sciences ,İstatistiksel ve Doğrusal Olmayan Fizik ,Mühendislik (çeşitli) ,MATERIALS SCIENCE, MULTIDISCIPLINARY ,Fizik ,Geotechnical Engineering ,photovoltaic (PV) ,fuel cell ,Metaller ve Alaşımlar ,Genel Mühendislik ,Alcaloides ,Media Technology ,performance analysis ,MALZEME BİLİMİ, ÇOKDİSİPLİNLİ ,Engineering, Computing & Technology (ENG) ,PHYSICS, APPLIED ,Engineering (miscellaneous) ,Process Chemistry and Technology ,distributed generation (DG) ,Mühendislik, Bilişim ve Teknoloji (ENG) ,Statistical and Nonlinear Physics ,General Chemistry ,MÜHENDİSLİK, ÇOK DİSİPLİNLİ ,Genel Kimya ,Fizik Bilimleri ,CHEMISTRY, MULTIDISCIPLINARY ,FİZİK, UYGULAMALI ,ENGINEERING, MULTIDISCIPLINARY ,Genel Malzeme Bilimi ,OPERATION ,Mühendislik ve Teknoloji ,Medya Teknolojisi ,Malzeme Bilimi - Abstract
Less energy consumption and more efficient use of renewables are among the sustainable energy targets of modern societies. The essential activities to be achieved under these objectives are to increase distributed generation (DG) structures’ applicability. DG systems are small-scale versions of the traditional power grid; they are supported by micro turbines, photovoltaics (PV) modules, hydrogen fuel cells, wind turbines, combined heat and power systems, and energy storage units. The aim of this research is to detail the performance analysis of a proton-exchange membrane fuel cell (PEMFC)-based grid-connected distributed generation system with the help of empirical calculations. To this end, we aimed to establish the system and analyze the performance of the reliable operation of the system with experimental verifications. The findings demonstrate how much power can be generated annually, through real meteorological data, to dispatch to constantly variable loads. While 53.56% of the total energy demand is met by the utility grid, 46.44% of the demand is met by the produced energy i.e., from the DG. The PEMFC-based DG system analyzed in detail in this study was located at Marmara University. According to the results of the performance analysis, significant points of this study will be highlighted to assist the researchers working in this field. Our results are encouraging and can be certified by a larger sample size with neat weather conditions in terms of the percentage of procurement of energy.
- Published
- 2023
46. Origin of Voids at the SiO2/SiO2 and SiCN/SiCN Bonding Interface Using Positron Annihilation Spectroscopy and Electron Spin Resonance
- Author
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F. Nagano, F. Inoue, A. Phommahaxay, L. Peng, F. Chancerel, H. Naser, G. Beyer, A. Uedono, E. Beyne, S. De. Gendt, and S. Iacovo
- Subjects
Technology ,Science & Technology ,SICN ,Physics ,Physical Sciences ,Materials Science ,Materials Science, Multidisciplinary ,Electronic, Optical and Magnetic Materials ,Physics, Applied - Abstract
To obtain reliable 3D stacking, a void-free bonding interface should be obtained during wafer-to-wafer direct bonding. Historically, SiO2 is the most studied dielectric layer for direct bonding applications, and it is reported to form voids at the interface. Recently, SiCN has raised as a new candidate for bonding layer. Further understanding of the mechanism behind void formation at the interface would allow to avoid bonding voids on different dielectrics. In this study, the void formation at the bonding interface was studied for a wafer pair of SiO2 and SiCN deposited by plasma enhanced chemical vapor deposition (PECVD). The presence of voids for SiO2 was confirmed after the post-bond anneal (PBA) at 350 °C by Scanning Acoustic Microscopy. Alternatively, SiCN deposited by PECVD has demonstrated a void-free interface after post bond annealing. To better understand the mechanism of void formation at the SiO2 bonding interface, we used Positron Annihilation Spectroscopy (PAS) to inspect the atomic-level open spaces and Electron Spin Resonance (ESR) to evaluate the dangling bond formation by N2 plasma activation. By correlating these results with previous results, a model for void formation mechanism at the SiO2 and the absence of for SiCN bonding interface is proposed.
- Published
- 2023
47. Case’s Method for Anlı-Güngör Scattering Formula
- Author
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R. Gökhan TÜRECİ and Ahmet BÜLBÜL
- Subjects
Case’s method,Case’s eigenfunctions,Mika scattering function,Anlı-Güngör scattering function ,Case metodu,Case özfonksiyonları,Mika saçılma formülü,Anlı-Güngör saçılma fonksiyonu ,Fizik, Uygulamalı ,General Medicine ,Physics, Applied - Abstract
Case metodu, tek-hızlı nötron transport denkleminin çözümünde güçlü bir metottur. Case metodu tek hızlı nötron transport problemlerine ve psedo-geometrilere uygulanabilir. Method, ilgilenen problemin özelliklerine göre belirli sınır şartlarıyla Case özfonksiyonları ve bu özfonksiyonlar arasındaki diklik bağıntılarının kullanımına dayanır. Saçılma etkileri Mika saçılma formülü ve İnönü saçılma formülü ile araştırılabilir. Bu çalışmada Case metodunun formalizmi, Mika saçılma fonksiyonunun analoğu olarak Anlı-Güngör saçılma formülü için türetilmiştir. Bu çalışma, Case özfonksiyonlarını, normalizasyon bağıntısını ve bu özfonksiyonlar arasındaki diklik bağıntıları ile ilgilidir ve dahası Anlı-Güngör saçılma formülündeki saçılma mertebesinin sayısı arttıkça Case özfonksiyonları ve diklik bağıntıları çalışılan saçılma parametresine göre yeniden yazılmalıdır., Case method is a powerful method in solving one-speed neutron transport equation. The method can be applied to one-speed neutron transport problems and pseudo- geometry problems. The method basis on the usage of Case’s eigenfunctions and the orthogonality relations with the certain boundary conditions according to the interested problem. The scattering effects can be investigated via Mika scattering formula and also İnönü’s scattering formula. In this study Case method’s formalism is derived by using Anlı-Güngör scattering formula as an analogue of Mika’s scattering function. This study is about the Case’s eigenfunctions, normalization relation and the orthogonality properties among these eigenfunctions and, moreover; Case’s eigenfunctions and the orthogonality properties must be rewritten according to the studied scattering order as the number of scattering order increase in Anlı-Güngör scattering formula.
- Published
- 2022
48. STING agonist delivery by tumour-penetrating PEG-lipid nanodiscs primes robust anticancer immunity
- Author
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Eric L. Dane, Alexis Belessiotis-Richards, Coralie Backlund, Jianing Wang, Kousuke Hidaka, Lauren E. Milling, Sachin Bhagchandani, Mariane B. Melo, Shengwei Wu, Na Li, Nathan Donahue, Kaiyuan Ni, Leyuan Ma, Masanori Okaniwa, Molly M. Stevens, Alfredo Alexander-Katz, Darrell J. Irvine, and Medical Research Council (MRC)
- Subjects
Technology ,AGGREGATE STRUCTURE ,Materials Science ,Materials Science, Multidisciplinary ,Physics, Applied ,ACTIVATION ,Neoplasms ,Humans ,General Materials Science ,Nanoscience & Nanotechnology ,Science & Technology ,MICELLES ,Chemistry, Physical ,Physics ,Mechanical Engineering ,Membrane Proteins ,General Chemistry ,Condensed Matter Physics ,CANCER ,Lipids ,Chemistry ,SIZE ,Physics, Condensed Matter ,Mechanics of Materials ,Physical Sciences ,Nanoparticles ,SHAPE ,Immunotherapy - Abstract
Activation of the innate immune STimulator of INterferon Genes (STING) pathway potentiates antitumour immunity, but systemic delivery of STING agonists to tumours is challenging. We conjugated STING-activating cyclic dinucleotides (CDNs) to PEGylated lipids (CDN-PEG-lipids; PEG, polyethylene glycol) via a cleavable linker and incorporated them into lipid nanodiscs (LNDs), which are discoid nanoparticles formed by self-assembly. Compared to state-of-the-art liposomes, intravenously administered LNDs carrying CDN-PEG-lipid (LND-CDNs) exhibited more efficient penetration of tumours, exposing the majority of tumour cells to STING agonist. A single dose of LND-CDNs induced rejection of established tumours, coincident with immune memory against tumour rechallenge. Although CDNs were not directly tumoricidal, LND-CDN uptake by cancer cells correlated with robust T-cell activation by promoting CDN and tumour antigen co-localization in dendritic cells. LNDs thus appear promising as a vehicle for robust delivery of compounds throughout solid tumours, which can be exploited for enhanced immunotherapy.
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- 2022
49. The Variation of the Linewidths and Amplitudes of Sub-Doppler Resonances of 87Rb D2 Line with Laser Beam Intensity
- Author
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Ersoy ŞAHİN
- Subjects
Fizik, Uygulamalı ,General Engineering ,Sub-Doppler resonance,linewidth,amplitude,saturation absorption spectroscopy,laser frequency stability ,Physics, Applied - Abstract
The sub-Doppler resonances linewidths and amplitudes depend on the laser beam intensity. The effect of laser beam intensity on the resonance linewidths and amplitudes obtained from different energy transitions of atoms varies from resonance to resonance. The effect of laser beam intensity on resonance linewidths and amplitudes is of great importance for diode laser frequency stability applications. It needs to be determined by measuring. The effect of the laser beam intensity on the linewidths and amplitudes of sub-Doppler resonances were measured by laser heterodyne spectroscopy using the linearly polarized frequency stabilized extended cavity diode lasers. The measurements are compatible with the theory and the uncertainty of the measurements are fewer than 1.6 MHz and 0.3 mV for linewidths and amplitudes, respectively.
- Published
- 2022
50. Calculation Of Gruneisen Parameter, Compressibility, And Bulk Modulus as Functions Of Pressure In (C6H5CH2NH3)2 PBI4
- Author
-
Arzu KURT
- Subjects
Bulk Modulus,Grüneisen Parameter,HOIPs,Phase Transition ,Fizik, Uygulamalı ,General Engineering ,General Earth and Planetary Sciences ,Physics, Applied ,General Environmental Science - Abstract
Hybrid organic-inorganic perovskites (HOIPs) exhibit multiple structural phase transitions, which result in enhanced mechanical and electronic properties of these perovskites. Order-disorder of organic components was thought to be the main factor to cause these phase transitions up to the last decade; however, recent research about HOIPs have shown that the structural phase transition also occurs with the induced pressure or temperature. The research studies related to the pressure have attracted a great deal of scholarly interest due to its contribution to the func-tionality of HOIPs in many current applications. Two-dimensional halide perovskites having been synthesized in the last few years have been increasingly studied thanks to its superior hysteresis in flexibility and mechanical properties under pressure. It is important to understand and model theoretically how induced pressure affects mechanical and electronic properties of (PMA)2PbI4 in order to develop new potential applications in optoelectronics. In this study, the isothermal mode-Grüneisen parameter, the isothermal compressibility, and the bulk modulus were calculated as functions of pressure at ambient temperature by using the calculated Raman frequencies and observed volume data for the selected IR modes in (PMA)2PbI4. These calculated parameters were compared with the observed measurements reported for the Pbca, Pccn and Pccn (isostructural) phases in the studied perovskites. The results obtained in the present study, which were highly compatible with the experimental measurements, showed that (PMA)2PbI4 is usable in optoelectronic applications.
- Published
- 2022
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