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Dynamic nuclear polarization transfers spin polarization from electrons to nuclei. We have achieved this by a new method, simultaneously exciting transitions of electronic and nuclear spins. The efficiency of this technique improves with increasing magnetic field. Experimental results are shown for N@C60 with continuous-wave microwaves, which can be expected to produce even higher polarization than the corresponding pulsed techniques for electron spins greater than 1/2. The degree of nuclear polarization in this case can be easily monitored through the intensities of the well-resolved hyperfine components in the electron paramagnetic resonance spectrum. The nuclear spin–lattice relaxation time is orders of magnitude longer than that of the electrons. [ABSTRACT FROM AUTHOR]

The Internet of Medical Things (IoMT) is increasingly utilized for patient health monitoring, treatment delivery, and healthcare enhancement. However, IoMT devices are vulnerable to attacks, posing risks to patient privacy and safety. Machine learning (ML) techniques are employed for attack detection to mitigate threats. IoMT devices generate substantial data, allowing ML algorithms to analyze and predict potential attacks. This study evaluates the performance of ML models for attack detection using datasets collected from medical devices. Both conventional and ensemble models are employed and trained on two datasets: one comprising all features and another with features selected based on importance. Ensemble models, which combine the strengths of multiple ML algorithms, are utilized to enhance detection accuracy and robustness. Results indicate that the ensemble model achieves superior detection rates and lower false positives than traditional ML algorithms. The stack ensemble model demonstrates the highest performance with a detection rate of 97.58%. Our proposed model outperforms existing models with a 5% improvement in detection rate and a 25% reduction in execution time. Proposed ensemble approaches hold promise for strengthening the security of IoMT devices and ensuring patient safety in fog-edge environments. [ABSTRACT FROM AUTHOR]

CH4@C60 was the first example within which an organic molecule has been embedded in C60. CH4 can rotate freely in the molecular cage, and the carbon skeleton structure of the C60 has no obvious deformation. The electronic structure of CH4@C60 and interaction between C60 and CH4 were studied under quantum mechanical calculation method. The different reaction sites on C–C bonds in C60 and the weak Van der Waals interaction between CH4 and C60 were shown clearly. These results and the orbital interaction between CH4 and C60 were helpful for understanding and further application of this unique biggest organic molecule CH4 contained in C60 structure so far. [ABSTRACT FROM AUTHOR]

Paramagnetic endohedral metallofullerenes with well protected unpaired spin have potential applications in molecular-scale qubit processing and magnetoreception system. In this study, a paramagnetic metallofullerene Sc3C2@C80 dimer with covalently bonded two spin centers was synthesized. Electron paramagnetic resonance (EPR) results further revealed the varied spin-nuclei couplings and paramagnetic property for Sc3C2@C80 dimer. Briefly, the Sc3C2@C80 dimer in toluene solution shows EPR hyperfine splittings originating from the spin-Sc couplings. However, the Sc3C2@C80 dimer in solid state shows the disappearance of hyperfine structure and a single EPR signal caused by its two-spin-center structure. The transformation of EPR signals can be further finely modulated by controlling the dynamic motion of Sc3C2@C80 dimer in chloronaphthalene. The Sc3C2@C80 dimer with two spin centers possesses varied paramagnetic properties, demonstrating its potential as new magnetic material. [ABSTRACT FROM AUTHOR]

Repeated single cavitation bubble experiments were performed primarily on 316L stainless steel, and some on nickel–aluminum–bronze (NAB) and pure aluminum. The bubble dynamics were recorded with two high-speed cameras and correlated with surface images, also acquired in situ. These experiments were performed for a range of stand-off distances γ (the ratio of the distance of the solid surface from the bubble to the bubble’s maximum radius) from 0.3 to 2.15. For all stand-off distances, single pits were the only surface change detected at the beginning of damage formation. Later phases of the collapse are not axisymmetric but show regions of “stronger” collapse, and the pits occur on the material underneath those regions. For γ < 0.4, the damage is attributed to the second collapse. For γ > 0.4, the first bubble collapse is most likely responsible for pitting. Shock-wave emission was detected from the collapse regions that were linked to the damage. On 316L, the pitting rate was found to be linearly dependent on the bubble radius, indicating a non-zero lower limit for the bubble radius below which pits do not occur. In terms of stand-off distance, the pitting rate (defined here as average pits per bubble) was non-monotonic, with maxima for bubbles initiated closest to the sample (γ = 0.3) and at γ = 1.4. [ABSTRACT FROM AUTHOR]

Millennials have the advantage of accessing readily available modern scientific advancements, particularly in technology. One of these technologies that encompasses varied functionalities is the Internet of Things (IoT). In the midst of the Covid-19 pandemic, IoT, specifically Internet of Medical Things (IoMT), had pivotal significance in monitoring and tracking different health parameters. It autonomously manages an individual's health data and stores the same as Electronic Health Records (EHRs). However, the networking protocols used by IoMT are not adequate enough to ensure the security and privacy of EHRs. Consequently, such technology is susceptible to cyber-attacks, which have become more prevalent over time and have taken various forms, that generally the stakeholders are not aware of. This paper introduces machine learning-driven intrusion detection systems as a solution to tackle this issue. The focus of this study is on devising a Machine Learning (ML) oriented Intrusion Detection System (IDS) designed to identify cyber-attacks targeting IoMT based systems. Several classification based ML techniques such as Multinomial Naive Bayes, Logistic Regression, Logistic Regression with Stochastic Gradient Descent, Linear Support Vector Classification, Decision Tree, Ensemble Voting Classifier, Bagging, Random Forest, Adaptive Boosting, Gradient Boosting and Extreme Gradient Boosting were used, whereupon the Adaptive Boosting was experimentally found to perform the best on performance metrics such as accuracy, precision, recall, F1-score, False Detection Rate (FDR) and False Positive Rate (FPR). Further, it was found that Adaptive boosting based IDS for IoMT performed comparatively better than the existing ToN_IoT based IDS models on performance metrics such as accuracy, F1-score, FPR and FDR. [ABSTRACT FROM AUTHOR]

Responsive synthetic receptors for adaptive recognition of different ionic guests in a competitive environment are valuable molecular tools for not only ion sensing and transport, but also the development of ion-responsive smart materials and related technologies. By virtue of the mechanical chelation and ability to undergo large-amplitude co-conformational changes, described herein is the discovery of a chameleon-like [2]catenane that selectively binds copper(I) or sulfate ions and its associated co-conformational mechanostereochemical switching. This work highlights not only the advantages and versatility of catenane as a molecular skeleton in receptor design, but also its potential in constructing complex responsive systems with multiple inputs and outputs. By virtue of the rotational motions of interlocked macrocycles, the authors describe a chameleon-like catenane host that can adjust its co-conformation for selective binding to copper(I) or sulfate ion. While the cationic copper(I) complex is achiral, the interlocked rings in the catenane host rotate and re-orient into a chiral co-conformation upon forming the anionic sulfate complex. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) devices are widely used but also vulnerable to cyberattacks that can cause security issues. To protect against this, machine learning approaches have been developed for network intrusion detection in IoT. These often use feature reduction techniques like feature selection or extraction before feeding data to models. This helps make detection efficient for real-time needs. This paper thoroughly compares feature extraction and selection for IoT network intrusion detection in machine learning-based attack classification framework. It looks at performance metrics like accuracy, f1-score, and runtime, etc. on the heterogenous IoT dataset named Network TON-IoT using binary and multiclass classification. Overall, feature extraction gives better detection performance than feature selection as the number of features is small. Moreover, extraction shows less feature reduction compared with that of selection, and is less sensitive to changes in the number of features. However, feature selection achieves less model training and inference time compared with its counterpart. Also, more space to improve the accuracy for selection than extraction when the number of features changes. This holds for both binary and multiclass classification. The study provides guidelines for selecting appropriate intrusion detection methods for particular scenarios. Before, the TON-IoT heterogeneous IoT dataset comparison and recommendations were overlooked. Overall, the research presents a thorough comparison of feature reduction techniques for machine learning-driven intrusion detection in IoT networks. [ABSTRACT FROM AUTHOR]

Particle size reduction by ultrasound is more favorable than conventional grinding due to its tendency to preserve the material's crystal structure. For palygorskite clay, the optimization was carried out using response surface methodology for the variables of sonication time, power, duty cycle, and clay loading. A 2FI model was fit to the dimensionless size number to navigate the design space of the model with an r-squared value of 0.9662. We found that the most optimal conditions for the size reduction were 45 min of sonication time, 110 W of sonication power, 90% duty cycle and 0.06 g/mL of clay loading. The loading and duty cycle terms had a positive effect on the particle size reduction, while an increase in power increased the particle size of the clay. The effect of time was found to be dependent on the values of the clay loading as well as the duty cycle. The XRD analysis of palygorskite clay for the untreated and treated samples indicated that ultrasound causes minimal changes to the crystal structure of the clay. The overall outcome of the study suggests that at optimal ultrasound conditions, particle size is reduced to ~ 1/16 times the initial value and the electric power input in the ultrasound generator takes an energy requirement of ~ 0.0124 kWh/g of solids processed for size reduction. [ABSTRACT FROM AUTHOR]

Butterfly valves are widely used in water supply systems, sewage treatment plants, chemical processes, and the natural gas industry to control and regulate the flow of fluids. When the liquid medium flows through a butterfly valve, the local pressure decreases rapidly because of the sudden change in the flow channel area, which leads to the cavitation generated at the downstream of butterfly valve if the local pressure is lower than saturated vapor pressure. This cavitation negatively affects the performance of the valve, causing severe vibration and noise. In some cases, this may affect the sealing performance and lifetime of the valve and could even lead to accidents. This paper mainly carried out experimental studies on the cavitation phenomenon inside butterfly valves. The cavitation evolution was recorded inside the butterfly valve at different opening degrees and pressure conditions by a high-speed camera, and the pressure was monitored at upstream and downstream of valve plate. The influences of valve opening degree and total pressure on dynamic evolution and distribution of cavitation was revealed. By comparing the distribution of vortices and cavitation bubbles in the flow field, it was found that vortices led to the aggregation of cavitation bubbles and changed the distribution of these bubbles in the flow field. We also analyzed the interaction between the cavitation and the surface of the butterfly plate. The shedding of the attached cavitation was mainly caused by a reentrant jet. [ABSTRACT FROM AUTHOR]

Efficient graphene production is critical for commercial applications. Liquid-phase exfoliation, one of the most promising methods for mass production of graphene, is limited by small size and low yield. By optimizing the fluid forces, we have achieved the size-controlled production of high-quality graphene. The bending and cleavage caused by the collision promote cavitation and shear exfoliation. High-aspect-ratio graphene has an average area of ~ 1.5μm2 and a thickness of ~ 1.5 nm. Simultaneously, the dispersion concentration of small size graphene (average area ~ 0.6μm2) is 0.17 mg mL−1, while the yield and efficiency reach 30% and 15%·h−1, respectively, through recycling sediment (initial concentration: 1 mg mL−1). Furthermore, the binary solvent of isopropanol and water is eco-friendly, low boiling, cost-effective. Jet collision can also be applied for exfoliation of other two-dimensional materials such as h-BN. This finding is essential for optimizing the design of liquid-phase exfoliation devices to obtain appropriate size and yield. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) is evolving in various sectors such as industries, healthcare, smart homes, and societies. Billions and trillions of IoT devices are used in e-health systems, known as the Internet of Medical Things (IoMT), to improve communication processes in the network. Scientists and researchers have proposed various methods and schemes to ensure automatic monitoring, communication, diagnosis, and even operating on patients at a distance. Several researchers have proposed security schemes and approaches to identify the legitimacy of intelligent systems involved in maintaining records in the network. However, existing schemes have their own performance issues, including delay, storage efficiency, costs, and others. This paper proposes trusted schemes that combine mean and subjective logic aggregation methods to compute the trust of each communicating device in the network. Additionally, the network maintains a blockchain of legitimate devices to oversee the trusted devices in the network. The proposed mechanism is further verified and analyzed using various security metrics, such as reliability, trust, delay, beliefs, and disbeliefs, in comparison to existing schemes. [ABSTRACT FROM AUTHOR]

Carbon nanotube field-effect transistor (CNT-FET) based sensor devices are widely used in sensing applications of biomolecules in high sensitivity. In addition, covalent functionalization process can increase the interaction between the CNTs and biological molecules. In this article, we present the effect of boronic acid functionalization on the electrical properties of the CNT-FET due to boronic acid and its derivatives have been widely used for the glucose recognition. For this purpose, CNT-FET transistors were fabricated on SiO2/Si substrates utilising high purity semiconducting nanotubes as the channel layer and functionalized with pyrene-1-boronic acid. It was found that boronic acid functionalization causes a variation in electrical parameters of CNT-FET transistors such as conductance, transconductance, threshold voltage, field effect mobility, resistance, hysteresis gap, and charge transfer of carriers per unit length. The results show that pyrene-1-boronic acid treatment was observed to have a significant beneficial effect on the electrical properties of the CNT-FET and pyrene-1-boronic acid functionalized CNT-FET sensor devices may have great potential for glucose sensing applications. [ABSTRACT FROM AUTHOR]

The Hildebrand solubility parameter has been applied in several areas of science and engineering, assuming a relevant role in new scientific developments and practical applications in industry. This review shows its importance and relationship with development of research in flow assurance activities, especially involving heavy fractions of oils such as asphaltenes, resins and wax. The examples described illustrate its relevance and scope in the approaches of interest of flow assurance. They also show that it is a versatile property for many new applications, including the development of methodologies to obtain more reliable values for the various petroleum fluids and theoretical developments for its estimation in a wide range of temperature and pressure. [ABSTRACT FROM AUTHOR]

Here, it is presented the fabrication of a low-cost and semitransparent three-layer graphene electrode (anode) based on an easily processable graphene derivative and the conductive polymer PH1000 (PEDOT:PSS). The graphene derivative was mechanically synthesized and suspended in water (SPGSW); its deposit was made directly by drop casting on a glass substrate. The multilayer nature of the SPGSW films was corroborated by Raman spectroscopy and a number of ∼ 7 graphene layers were estimated for the SPGSW film treated with hydroiodic acid (HI) and UV-ozone plasma, which was also corroborated theoretically (∼ 6 graphene layers). Furthermore, for the SPGSW film, a thickness of ∼ 5 nm was determined experimentally. The alternative three-layer graphene electrode showed a transmittance and an electrical resistance of ∼ 78% (at 550 nm) and ∼ 88 Ω/sq, respectively. These results are promising for this alternative electrode based on the graphene derivative and for potential application in photovoltaic devices beside other uses. [ABSTRACT FROM AUTHOR]

Binary and ternary complexes of europium fullerenes and diphthalocyanines with detonation nanodiamonds are obtained for the first time, which can serve as platforms for the delivery of these hydrophobic molecules into aqueous biological media for magnetic resonance imaging, photodynamic therapy, and diagnostics using luminescent labels. Detonation nanodiamonds (~4–5 nm in size) have a positive potential (30–70 mV) in an aqueous medium due to the groups (CH, COH) grafted to the surface by heat treatment in an atmosphere of hydrogen. When positively charged diamonds interact with electronegative hydrated fullerenes in an aqueous medium, the initial aggregates of each of the components are destroyed, and the electrostatic attraction between them leads to the formation of stable compact complexes ~20 nm in size, according to dynamic light scattering and neutron scattering in colloids (20°C). Binary complexes include, on average, two fullerene molecules per 30–40 diamond particles. Introducing diphthalocyanine molecules into a binary colloid yields stable ternary structures. The resulting complexes of diamonds, fullerenes, and diphthalocyanine molecules are promising for biomedical applications due to the luminescent and magnetic properties of the components. [ABSTRACT FROM AUTHOR]

The mechanism of detonation synthesis of nanocarbons was successfully applied to obtaining 2D graphene structures. To this end, rejecting the composite explosive and switching to pure trinitrotoluene for optimizing the energy efficiency of the detonation synthesis was suggested. The validity of the proposed phenomenological model was confirmed by experimental data. Using a set of complementary research methods (electron microscopy, Raman spectroscopy, dynamic light scattering), a good agreement was demonstrated between the morphometric parameters of the synthesized powder particles and those characteristic of 2D graphene structures, graphene nanoplates (GNP). The obtained results allowed a conclusion that the proposed method offers a much more eco-friendly solution to the problem of disposal of expired ammunition compared to existing methods. [ABSTRACT FROM AUTHOR]

Encapsulation of atoms or small molecules inside fullerenes provides a unique opportunity for study of the confined species in the isolated cavity, and the synthesis of closed C60 or C70 fullerenes with enclosed atoms or molecules has recently developed using the method of 'molecular surgery'; in which an open-cage intermediate fullerene is the host for encapsulation of a guest species, before repair of the cage opening. In this work we review the main methods for cage-opening and closure, and the achievements of molecular surgery to date. 'Molecular surgery' is a useful method through which to create endohedral fullerenes that aren't accessible by conventional physical methods of trapping small atoms and molecules. Here, the authors review the organic chemistry behind molecular surgery, describing the methods to access open-cage intermediates alongside the cage-closing chemistry. [ABSTRACT FROM AUTHOR]

Large-scale triage after major radiological events, such as nuclear reactor accidents, requires a method of ionizing radiation dose estimation called retrospective biodosimetry (RBD) to detect doses in the range of 0.5–8 Gy. A well-known technique for performing RBD is electron spin resonance (ESR), which can be used to measure radiation-induced paramagnetic defects in the enamel of the teeth. The concentration of these defects is linearly correlated with radiation doses in the applicable range. Despite its great potential and proven results when applied to extracted teeth, ESR still struggles to provide accurate in vivo readings. This is mainly because all available ESR-based RBD methods rely on quantitative signals for calculating the concentration of paramagnetic defects in tooth enamel to evaluate the dose. This requires an accurate knowledge of the volume of the measured enamel, which is very difficult to achieve in live subjects (since teeth also include dentin and possibly cavities). Here, we examine radiation-induced paramagnetic defects in the enamel layer of human teeth using advanced pulsed ESR methods, with the ultimate goal of supporting the development of an innovative practical RBD device for in vivo use. We employ a variety of pulsed ESR techniques, such as ESR measurements of spin–spin relaxation time (T2), ESR monitoring of instantaneous diffusion decay time (TID), and dipolar ESR spectroscopy, to explore their possible use to quantify the irradiation dose. Moreover, we develop a special resonator for teeth measurements that make use of such pulse techniques to overcome the constrains of small signal magnitudes and short coherence times. Our results show a good correlation between measured values of T2, TID, and the irradiated dose, but further work is required to improve the robustness, accuracy, and sensitivity of the methods presented before they could possibly be applied for in vivo measurements in typical doses of ~ 2–8 Gy. These findings and approaches may be used in the future for the development of a RBD device to evaluate ionizing radiation doses without prior knowledge of the measured enamel volume. [ABSTRACT FROM AUTHOR]

Ultrasonic treatment is effective in deagglomerating and dispersing nanoparticles in various liquids. However, the exact deagglomeration mechanisms vary for different nanoparticle clusters, owing to different particle geometries and inter-particle adhesion forces. Here, the deagglomeration mechanisms and the influence of sonotrode amplitude during ultrasonication of multiwall carbon nanotubes in de-ionized water were studied by a combination of high-speed imaging and numerical modeling. Particle image velocimetry was applied to images with a higher field of view to calculate the average streaming speeds distribution. These data allowed direct comparison with modeling results. For images captured at higher frame rates and magnification, different patterns of deagglomeration were identified and categorized based on different stages of cavitation zone development and for regions inside or outside the cavitation zone. The results obtained and discussed in this paper can also be relevant to a wide range of carbonaceous and other high aspect ratio nanomaterials. [ABSTRACT FROM AUTHOR]

Quantum public-key cryptography (QPKC) can perform the management and distribution of keys in a large-scale quantum communication network, thus being the foundation for many cryptographic applications. The QPKC system, which uses qubit rotation as a quantum one-way function, is one of the most practical public key systems and has found many valuable extensions. In this paper, we analyze and provide supplementary properties of binary qubit rotation. On the basis of Nikolopoulos'work (Phys Rev A 77(3):032348, 2008), we have extended the qubit rotation to three dimensions and propose a ternary QPKC protocol. The protocol can resist forward search attack and achieve higher security than binary QPKC protocol. Theoretically, the protocol can be extended to a higher dimension. [ABSTRACT FROM AUTHOR]

Quantum state control is one of the most important concepts in advanced quantum technology, emerging quantum cybernetics and related fields. Molecular open shell entities can be a testing ground for implementing quantum control technology enabling us to manipulate molecular spin quantum bits (molecular spin qubits). In well-designed molecular spins consisting of unpaired electron and nuclear spins, the electrons and nuclear spins can be bus and client qubits, respectively. Full control of molecular spin qubits, in which client spins interact via hyperfine coupling, is a key issue for implementing quantum computers (QCs). In solid-state QCs, there are two approaches to the control of nuclear client qubits, namely, direct control of nuclear spins by radio-wave (RF) pulses and indirect control via hyperfine interactions by microwave pulses applied to electron spin qubits. Although the latter is less popular in the literature, the indirectness has advantage of greatly reducing unnecessary interactions between a qubit system and its environment. In this work, we investigate molecular spin optimization to find optimal experimental conditions which can afford to achieve the high fidelity of quantum gates by the indirect control scheme. In the present quantum systems, one electron is directly controlled by pulsed ESR techniques without manipulating individual hyperfine resonance, but the states of two nuclear client spins are indirectly steered via hyperfine interactions. Single crystals of potassium hydrogen maleate (KHM) radical and 13C-labeled malonyl radical are chosen as typical molecular spin qubits which exemplify the importance of the symmetry of hyperfine tensors and their collinear properties. We have found that both the non-collinearity of the principal axes of hyperfine coupling tensors and the non-distinguishability/non-equivalency between nuclear spins are key issues which extremely reduce the gate fidelity. [ABSTRACT FROM AUTHOR]

Ultrasound-assisted liquid-phase exfoliation is a promising method for manufacturing two-dimensional materials. Understanding the effect of ultrasonication parameters such as the temperature and input power on the developed pressure field is pivotal for optimization of the process. Limited research has been carried out to determine the optimal temperature for exfoliation, with some data generating disputed results. Simply maximizing the sonication power does not necessarily produce a higher yield because of shielding. In this study, a high-temperature calibrated cavitometer was used to measure the acoustic pressure generated in different graphite solutions in deionized water at various temperatures (from 10°C to 70°C) and input power conditions (from 20% to 100%). In addition, high-speed optical imaging provided insight on the shock wave generation from transient bubble collapses under different sonication conditions. The optimal sono-exfoliation parameters were determined to be 20% input power at 10°C for graphite flake solution, and 100% input power at 40°C to 50°C for graphite powder solution. [ABSTRACT FROM AUTHOR]

A four-terminal ballistic rectifier demonstrating voltage rectification for both electrical (AC/DC) as well as thermal (temperature gradient) inputs is presented. The thermoelectric behavior of the graphene triangular ballistic rectifier (G-TBR) is based on its nonlinear electrical response. The responsivity and noise equivalent power of the device are calculated to be 8870 mV/W and 1.59 nW/Hz1/2, respectively, at a back-gate voltage of 5 V. The rectified thermal voltage between two isothermal output (lower and upper) terminals is estimated to be 2.8 µV at a temperature gradient of 150 K. Further, the electric and thermoelectric output of the proposed G-TBR is validated by analytical modeling. Such G-TBRs could be used in the future in energy harvesting application to use heat produced by electronic circuitry, integrated circuits (ICs), etc. [ABSTRACT FROM AUTHOR]

Integrating multiple photosensitive properties into an "all-in-one" photosensitizer (PS) shows great promise for the treatment of cancers owing to synergistic effect among them. However, the development of such PSs, especially those that need a single laser source, remains a challenge. Herein, we report an orchestration of electron donors and acceptors in a propeller-like pentad, PBI-4Cz, where four carbazole (Cz) units are covalently linked to the ortho-positions of the perylene bisimide (PBI) core. Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region. Excited-state dynamics investigated via femto- and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved. Energy dissipation of the resulting charge-separated state (PBI•−-4Cz•−) is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states. Relative importance of the two pathways can be tuned by micro-environmental polarity, which endows PBI-4Cz remarkable performances of singlet-oxygen generation (>90.0%) in toluene and photothermal conversion (∼28.6%) in DMSO. Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics, but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations using density functional theory, this paper systematically studies the effects of uniaxial tension-compression deformation on the stability and electrical and thermal properties of monolayer graphene and AA stacked bilayer graphene. The study shows that the original symmetry of graphene is broken by the tensile and compression deformations, catalyzing the interlayer coupling of bilayer graphene. Its electronic energy band, phonon dispersion, and other physical properties have changed. The transition from metalloid to semiconductor has completed since the deformation weakens the stability of the graphene system to varying degrees and opens the band gap of monolayer graphene. The band gap becomes larger with the increase of tensile and compressive deformation, in which way it can be adjusted. Influenced by the tiny tensile deformation, metalloid properties are exhibited by a small band gap of intrinsic AA-stacked bilayer graphene, and then the band gap becomes larger as the deformation increases. A band gap appears in the system phonon dispersion curves when the compression deformation increases to −15%. The phonon mode softens and shows virtual frequency. The value of virtual frequency increases with the increase of compression deformation. At the very moment, the vibration mode is discontinuous, and the system is unstable. [ABSTRACT FROM AUTHOR]

Charge transfer architectures have attracted wide attention due to their advantages of easy probing and higher solvent tolerance, making it possible to construct charge transfer assemblies in a wide range of organic and aqueous media. 1, 4, 5, 8-Naphthalenediimides (NDIs) have been widely used as electron-deficient acceptors to construct charge transfer complexes with a variety of electron-rich donors. In this review, we introduced various supramolecular charge transfer assemblies based on NDIs that have undergone vigorous development in the past decade, including catenanes, rotaxanes, supramolecular polymers and gels. Due to the intrinsic weak nature of aromatic charge transfer interactions, highly organized structures were proved to be a result of multiple cooperative non-covalent interactions in most cases. In this review, we aim to shed light on the future design of NDI-based supramolecular structures and their applications in the real world. We in this review chose three types of NDI based charge transfer structures that have attracted considerably attentions throughout the last 10 years and systematically discussed their design strategies, structures and their characteristic features. [ABSTRACT FROM AUTHOR]

High-spin magnetic molecules are promising candidates for quantum information processing because their intrinsic multiplicity facilitates information storage and computational operations. However, due to the absence of suitable sublevel splittings, their susceptibility to environmental disturbances and limitation from the selection rule, the arbitrary control of the quantum state of a molecular electron multiplet has not been realized. Here, we exploit the photoexcited triplet of C70 as a molecular electron spin qutrit with pulsed electron paramagnetic resonance. We prepared the system into 3-level superposition states characteristic of a qutrit and validated them by the tomography of their density matrices. To further elucidate the coherence of the operation and the nature of the system as a qutrit, we demonstrated the quantum phase interference in the superposition. The interference pattern is further interpreted as a map of possible evolution paths in the space of phase factors, representing the quantum nature of the 3-level system. [ABSTRACT FROM AUTHOR]

The diffusion at atomic scale is of considerable interest as one of the critical processes in growth and evaporation as well as a probe of the forces at an atomically flat reconstructed surface. This atomic-scale migration is critical to investigate in strontium titanate (SrTiO3) as it possesses the same status in oxide electronics as does silicon in ordinary electronics based on elemental semiconductors. Here we show that (001) terminated SrTiO3 reconstructed surface is atomically unstable enough to allow atom-vacancy hopping at room temperature. In this work, SrTiO3 (001) single crystal (7 × 2 × 0.5 mm) was sputtered (0.5 keV, 2.5 µA, 10 min) and annealed multiple times in ultra-high vacuum (UHV) and imaged using scanning tunneling microscope (STM). A relatively unstable surface was observed at low-temperature annealing and tip–surface interactions caused dislocation of mass at the surface. Both square and zig-zag nanolines were observed with atomic resolution where an atom-vacancy hopping was observed in a square diline while imaging at room temperature. The hopping was ceased when sample was annealed at higher temperature and a more compact network of nanolines was achieved. [ABSTRACT FROM AUTHOR]

Highlights: Ultrathin and defect-free graphene ink is prepared through a high-throughput fluid dynamics process, resulting in a high exfoliation yield (53.5%) and a high concentration (47.5 mg mL−1). A screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 104 S m−1 and good mechanical flexibility. An electrochemical sodium ion sensor based on graphene ink exhibits an excellent potentiometric sensing performance in a mechanically bent state. Real-time monitoring of sodium ion concentration in sweat is demonstrated. Conductive inks based on graphene materials have received significant attention for the fabrication of a wide range of printed and flexible devices. However, the application of graphene fillers is limited by their restricted mass production and the low concentration of their suspensions. In this study, a highly concentrated and conductive ink based on defect-free graphene was developed by a scalable fluid dynamics process. A high shear exfoliation and mixing process enabled the production of graphene at a high concentration of 47.5 mg mL−1 for graphene ink. The screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 104 S m−1 and maintains high conductivity under mechanical bending, compressing, and fatigue tests. Based on the as-prepared graphene ink, a printed electrochemical sodium ion (Na+) sensor that shows high potentiometric sensing performance was fabricated. Further, by integrating a wireless electronic module, a prototype Na+-sensing watch is demonstrated for the real-time monitoring of the sodium ion concentration in human sweat during the indoor exercise of a volunteer. The scalable and efficient procedure for the preparation of graphene ink presented in this work is very promising for the low-cost, reproducible, and large-scale printing of flexible and wearable electronic devices. [ABSTRACT FROM AUTHOR]

Metal nitride clusterfullerenes (NCFs) have significant applications in molecular electronics, biomedical imaging, and nonlinear optical devices due to their unique structures. However, their wide applications are limited by the production quantity. In this work, the yields of metal nitride clusterfullerenes M3N@C80 (M=Y, Sc, Gd) were greatly enhanced by utilizing zirconium nitride (ZrN) as an efficient nitrogen source for the arc-discharge method. Compared with the traditional synthetic route using N2 gas as nitrogen source, the ZrN inside graphite tube can be vaporized simultaneously with metal and graphite, and then afford the high concentration of nitrogen atoms in the arc region, which will promote the formation of metal nitride clusterfullerenes finally. The ZrN can promote the yields of Y3N@C80, Sc3N@C80 and Gd3N@C80, revealing the universal applicability of ZrN as a highly efficient nitrogen source. Specifically, the yield of Sc3N@C80 was greatly improved when adding ZrN, and it shows over double yield compared to traditional synthetic route using N2 gas. In addition, ZrN can also enhance the yields of paramagnetic azametallofullerene M2@C79N due to the high concentration of nitrogen atoms in the arc region. This new method enhances the production quantity of metal nitride clusterfullerenes and azametallofullerenes, and it will greatly promote the research and application of these molecular carbon materials. [ABSTRACT FROM AUTHOR]

In a typical EPR experiment, the transitions require that the static magnetic field B 0 is oriented perpendicular to the microwave field B 1 (perpendicular mode). This is determined by the transition rules either in the classical or in the quantum mechanical description. However, there are cases where EPR transitions are observed when B 0 is oriented parallel to B 1 (parallel mode). Quite numerous studies can be found in the literature where EPR transitions in both modes (dual-mode EPR) are feasible. In the majority of cases, dual-mode EPR studies are typically applied in S > 1 / 2 systems where non-zero transition probabilities for the parallel mode are the result of the state mixing provided by the zero-field splitting interaction. On the other hand, the observation of parallel-mode EPR signals in S = 1 / 2 systems becomes feasible when strong hyperfine interaction between the electronic and nuclear spin is present, as has been theoretically predicted for the hydrogen atom having a hyperfine coupling constant of A 0 = 1420 MHz (Weil in Concepts Magn Reson Part A 28:331, 2006). Herein, we report the first dual-mode X-band EPR experiments of hydrogen atom (both isotopes 1 H and 2 H) encapsulated in polyhedral oligomeric silsesquioxane cages. We extend the theory to the case of deuterium and we extract analytical formulas for transition probabilities. For the forbidden transitions, this study revealed a first-order dependence of resonance fields on the nuclear g-factor, g n , and the existence of a clock transition with f = 307 MHz. [ABSTRACT FROM AUTHOR]

The present work aims to investigate experimentally the crack arrest capability and dynamic fracture mechanisms under impact loading of three commercial, rubber-toughened (RT) PMMA grades differing by their rubber nano-particle concentration and resulting Charpy impact toughness. For that purpose, Kalthoff and Winkler (KW)-like impact tests were performed using gas launcher considering impact velocities ranging between 20 and 100 m/s. A high-speed camera was used to record the projectile/specimen interaction and the progressive failure of the specimen. The fracture surfaces of the fragments were observed using a scanning electron microscope (SEM). It is seen that the higher the impact velocity the larger the number of fragments. On the other hand, it is shown that increasing the rubber nano-particle concentration favors the crack arrest capability under impact loading by promoting inelastic deformation, reducing the crack propagation velocity, limiting crack multi-branching, and reducing the number of fragments. [ABSTRACT FROM AUTHOR]

Nowadays, biomaterials have become a crucial element in numerous biomedical, preclinical, and clinical applications. The use of nanoparticles entails a great potential in these fields mainly because of the high ratio of surface atoms that modify the physicochemical properties and increases the chemical reactivity. Among them, carbon nanotubes (CNTs) have emerged as a powerful tool to improve biomedical approaches in the management of numerous diseases. CNTs have an excellent ability to penetrate cell membranes, and the sp2 hybridization of all carbons enables their functionalization with almost every biomolecule or compound, allowing them to target cells and deliver drugs under the appropriate environmental stimuli. Besides, in the new promising field of artificial biomaterial generation, nanotubes are studied as the load in nanocomposite materials, improving their mechanical and electrical properties, or even for direct use as scaffolds in body tissue manufacturing. Nevertheless, despite their beneficial contributions, some major concerns need to be solved to boost the clinical development of CNTs, including poor solubility in water, low biodegradability and dispersivity, and toxicity problems associated with CNTs’ interaction with biomolecules in tissues and organs, including the possible effects in the proteome and genome. This review performs a wide literature analysis to present the main and latest advances in the optimal design and characterization of carbon nanotubes with biomedical applications, and their capacities in different areas of preclinical research. [ABSTRACT FROM AUTHOR]

In this article, we report the self-assembly process, structural features, thermal and hydration properties of the gold fullerene nanocomposite at room temperature by applying molecular dynamics simulation technique. The gold-fullerene systems constituting alkanethiol capped gold nanoparticle and pristine fullerene in explicit water have been simulated to gain insights on the influence of the terminal methyl (hydrophobic) and hydroxy (hydrophilic) groups on their structure and properties. The physisorption of the fullerene molecule into the thiol layer of the gold nanoparticle has been demonstrated and elucidated. The chemical functionality of the terminal groups was found to affect the structure, specific heat capacity and the wetting behavior of the gold-fullerene nanocomposite. The findings from this computational study may aid the understanding and development of novel gold-fullerene nanostructures for modulating their structural, thermal and hydration properties through the modification of their surface functional groups. [ABSTRACT FROM AUTHOR]

In the present work, we provide a theoretical treatment of pulsed Overhauser-type dynamic nuclear polarization (DNP) in the presence of spectral exchange, namely, Heisenberg exchange. The expression for the DNP enhancement of a nuclear magnetic resonance (NMR) signal is generalized by redefining the "deviation factor", expressing the deviation of the electron spin polarization from its equilibrium value, averaged over the period of the pulse sequence. We can demonstrate that spectral exchange significantly increases the deviation factor and, thus, the NMR enhancement. The present treatment allows one to determine the optimal pumping frequency at different exchange rates. [ABSTRACT FROM AUTHOR]

Fullerene derivatives as a kind of star carbon materials have received intense investigation because of their three-dimensional shape, anisotropic electron mobility, and high electron affinity. Indeed, the cutting-edge developments of fullerene nanomaterials have had a tremendous impact on a wide range of applications, such as organic solar cells, field effect transistors, and photodetectors. To explore their full potential applications, research into fullerene-based multilevel nanostructures relying on hierarchical interactions from bottom to top is rapidly expanding. It is of great theoretical and practical significance to prepare multilevel fullerene nanostructures with structural and properties controlled by optimizing the influencing factors. This review would offer several aspects including the chemical structures of organic molecules and the nanostructures of the organic molecules and fullerene-organic complexes. Whether monolayers or multilayers, fullerene molecules tend to fall into a space of suitable size, in which the located positions are affected by the intermolecular interactions. For the covered surfaces, fullerenes are more likely to approach the electron-withdrawing units through the donor–acceptor and charge transfer interaction. Through the implementation of this review, an exhaustive analysis on the chemical modification, including the molecular backbone and substituents, preformed network synergies, and adsorption sites is presented. In addition, the relationship between the molecules and structures that illustrates the importance of the molecular design for the controlled fullerenes hybrid nanostructures can be further understood based on the results of the joined experimental and computational investigations. [ABSTRACT FROM AUTHOR]

In this study, finite element analysis and nano-indentation experiments were carried out to investigate the effect of surface tilt on the nanoindentation test results. This paper revealed that standard Oliver–Pharr method underestimated the contact area due to the influence of the tilt condition. Consequently, it is necessary to compensate this difference to ensure that the result is reliable. The finding was verified by the nano-indentation experiments on a sinusoidal surface sample, which is used for the study of correlation between surface topography and its mechanical properties. A corrective action was implemented to compensate the errors by finite element analysis. By eliminating such errors, the study of the relationship between surface topography and mechanical properties was performed and discussed. [ABSTRACT FROM AUTHOR]

Recent preparation of black phosphorene and subsequent discovery of its excellent optical and electronic properties have attracted great attention, and renewed interest to phosphorus. Recent researches have indicated that phosphorus structures are promising anodes for lithium-ion and sodium-ion batteries. A high theoretical capacity of 2,596 mAh·g−1 was predicted for phosphorus according to the reaction of 3Li/Na + P → Li3P/Na3P. However, fast capacity degradation is accompanying with most phosphorus structures due to the low electronic conductivity and structural pulverization induced by large volume change in charging and discharging proceses. The electrochemical performances are significantly affected by the hierarchical structural design of phosphorus. A few reviews of phosphorus structures have been reported recently. However, no review about the electrochemical performances of phosphorus structures according to their hierarchical structures has been reported. First of all, phosphrus allotropes along with their structure and fundamental properties are briefly reviewed in this work. Secondly, the studies on lithiation/sodiation mechanism of red/black phosphorus are presented. Thirdly, a summary about the electrochemical performances of red/black phosphorus composites with different hierarchical structures is presented. Furthermore, the development challenges and future perspectives of phosphorus structures as anodes for LIBs and SIBs are discussed. [ABSTRACT FROM AUTHOR]

Relaxation times were measured at X-band (9.5 GHz) at concentrations up to 20.8 mM for two nitroxides that are widely used in Overhauser dynamic nuclear polarization (ODNP) experiments. Carboxy proxyl (CP, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy) in water and tempol (TP, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) in toluene have been studied with oxygen removed. For comparison, solutions of CP were also studied in air-saturated solution, which is the typical preparation for ODNP experiments. T2 and T2HE (HE = Heisenberg exchange) were measured by electron spin echo. The spin magnetization recovery time constant from inversion recovery experiments, which we denote as T1e*, includes contributions from T1e and T1HE. In the absence of oxygen, values of T1e* for both radicals decrease with increasing concentration up to ~ 1 mM, then increase again towards 10 mM. The concentration dependence results from changes in the relative contributions from T1e and T1HE. In air-saturated solutions of CP T1e* decreases with concentration to about 200 ns at 1 mM, and then remains independent of further concentration increases. T1e and T1N were also measured with a digital saturation recovery spectrometer. Using the combined results from spin echo, inversion recovery, and saturation recovery we could extract the values of T1e, T1HE, T1N, T2e, and T2HE for both radicals in this fast tumbling regime. [ABSTRACT FROM AUTHOR]

In the present work, the channels of metallicity-sorted metallic single-walled carbon nanotubes (SWCNTs) have been filled with silver chloride. The data of high-resolution scanning transmission electron microscopy proved the filling of the nanotube channels and formation of few-atom-thick crystals of silver chloride. The electronic properties of the filled SWCNTs were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. Our results indicate the p-doping of nanotubes by silver chloride accompanied by the charge transfer from the nanotubes to the encapsulated compound and the downshift of the Fermi level by 0.36 eV. The calculated number of transferred electrons per nanotube carbon atom and the charge transfer density per nanotube length amounted to 0.0024 e− per carbon and 0.0406 e−/Å, respectively. It was found that the band gap opens up in the band structure of the filled SWCNTs resulting in their transition from metallic into a semiconducting state. This work reveals a direct influence of the incorporated silver chloride on the electronic properties of metallicity-sorted metallic SWCNTs and demonstrates the potential of precise Fermi level engineering of SWCNTs by filling their channels and achieving high doping levels, thus providing a platform for designing next-generation nanoelectronic devices. [ABSTRACT FROM AUTHOR]

A novel multi-function stylus profiling system has been developed for characterizing surface properties at micro/nanometer scales. The multi-function stylus profiling system provides, within one set-up arrangement, measurements of topography, friction, Young’s modulus and hardness of a surface. The measurement is based on point-by-point scanning so that the four measured functions can be correlated in space and in time. It targets an area that is of growing importance to a wide range of technologies where function-orientated surfaces/coatings are in demand. The essential part of the multi-function stylus profiling system is a special sensing probe, which has an electromagnetic force actuator and three precision capacitive sensors for simultaneous measurements of surface height/deformation and friction force between the probe tip and the surface being scanned. The system provides a controllable loading force in a range of 0.05-20 mN. The topography measurement has a maximum range of 20 µm. The scanning area of 100 µm × 100 µm is closed-loop controlled with an accuracy of 1 nm. Design, analysis, and experimental investigation of the multi-function stylus profiling system are carried out. Evaluations are carried out on certain material surfaces to demonstrate the capability of the system. [ABSTRACT FROM AUTHOR]

A new composite has been developed from natural rubber and chrome-tanned leather waste for use in footwear and textile industries. The contribution of this material to environmental quality and sustained development should be highligh because chrome tanned leather wastes, a major environmental problem, can be recycled. However, the safety of this new material for human use is questionable, as it is already well reported in the literature that chromium, particularly in its hexavalent oxidation state, can be genotoxic and carcinogenic to living beings. Thus, the aim of this study was to evaluate in vitro biocompatibility of this composite material for possible use in the footwear and textile industries, through cytotoxicity, cell adhesion, and genotoxicity tests. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure both concentrations of total and hexavalent chromium. Based on the findings, it was concluded that the composite exhibits low levels of cytotoxicity and genotoxicity, and possesses favorable properties for initial cell adhesion. Furthermore, it was verified that the composites released low concentrations of chromium and that the predominant species released would be trivalent chromium. The results of the present study open the possibility of the incorporation of solid residues of tanned leather into chromium without necessarily the chromium contained in these residues influences the toxicity and genotoxicity of this new material. [ABSTRACT FROM AUTHOR]

Glossiness is an optical index representing the capacity of a surface to reflect light, which is vital criteria for components in need of esthetic appearance. To achieve the stringent glossiness requirement, sanding and polishing for smooth surface generation become the necessary material removal method. However, the intrinsic correlation of surface roughness and glossiness is still not clear. Small roughness value does not always guarantee perfect glossiness, and high surface glossiness does not always require extreme surface roughness perfection. In this paper, the surface topography features and glossiness conditions are analyzed for sanded and polished surfaces. And the surface glossiness is modeled and simulated for surfaces generated with non-Gaussian topography features manufactured by sanding and polishing. Finally, the critical surface topography parameters are identified to establish the correlation with the surface glossiness. [ABSTRACT FROM AUTHOR]