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Ceramic nanostructures with their unique morphologies have attractive properties and various biomedical and medical applications. The production of nanoparticles (NPs) with a special morphology has been strongly influenced by lab-scale synthesis conditions and the type of reducing agents. Generally, the production of NPs with unique shapes and sizes can be adjusted by changing and optimizing the reaction mixture conditions and parameters. The formation of ceramic nanostructures during synthesis process contained the nucleation, seeding, and growth steps. By altering the kinetics and thermodynamics of synthesis process (at each stage), the shape of the produced nanostructures can be controlled. In this study, nickel ferrite ceramic nanoribbons were produced through a green and environmentally-friendly method based on the bioethical principles of preventing environmental damage, without using any other chemical composition, and only by applying plant extracts as reducing and stabilizing agents. The prepared ceramic nanoribbons were evaluated by XRD, SEM, FTIR, VSM, and HR-TEM. The results confirmed that the calcination could significantly affect the size and shape of the resulting ceramic nanostructures. The calcination could lead to the deformation of thin and hair-like ceramic nanoribbons into spherical NPs (∼20 nm). Additionally, the antiparasitic properties of these nanoribbons were evaluated using MTT method, and the antifungal effects were analyzed against Aspergillus ustus. The obtained results illustrated that these nanostructures had significant toxicity against Leishmania tropica and A. ustus.

In general, the growing resistance to traditional anti-leishmaniasis drugs and the ineffectiveness of appropriate treatment for leishmaniasis have prompted researchers to investigate the antiparasitic properties of plant-mediated synthesized nanomaterials and nanosystems. Potassium (K)-doped zinc oxide (ZnO) nanostructures with unique physicochemical properties can be employed as attractive candidate against this parasitic disease. In this study, K-doped zinc oxide (KdZ) nanoparticles (NPs) were synthesized using Artemisia annua extracts via an eco-friendly method with the advantages of simplicity, low cost, and up-scalability. A. annua extracts were deployed due to their antiparasitic effects. The synthesized NPs were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The toxicity of these nanostructures was evaluated on Leishmania tropica and normal macrophage cells. As a result, the K-doped ZnO NPs could inhibit the L. tropica cells growth, in vitro.

Purpose The purpose of this study is to investigate the post-buckling analysis of functionally graded columns by using three analytical, approximate and numerical methods. A pre-defined function as an initial assumption for the post-buckling path is introduced to solve the differential equation. The finite difference method is used to approximate the lateral deflection of the column based on the differential equation. Moreover, the finite element method is used to derive the tangent stiffness matrix of the column. Design/methodology/approach The non-linear buckling analysis of functionally graded materials is carried out by using three analytical, finite difference and finite element methods. The elastic deformation and Euler-Bernoulli beam theory are considered to establish the constitutive and kinematics relations, respectively. The governing differential equation of the post-buckling problem is derived through the energy method and the calculus variation. Findings An incremental iterative solution and the perturbation of the displacement vector at the critical buckling point are performed to determine the post-buckling path. The convergence of the finite element results and the effects of geometric and material characteristics on the post-buckling path are investigated. Originality/value The key point of the research is to compare three methods and to detect error sources by considering the derivation process of relations. This comparison shows that a non-incremental solution in the analytical and finite difference methods and an initial assumption in the analytical method lead to an error in results. However, the post-buckling path in the finite element method is traced by the updated tangent stiffness matrix in each load step without any initial limitation.

In recent years, nanostructures and nanoarchitectures have attracted much attention in the development of biomedicine and nanomedicine. The plant-mediated synthesis of barium carbonate nanoparticles (BACN) has been performed using barium chloride and aqueous extract of natural sweetener (Stevia). In this study, the biosynthesis of BACN has been selected due to the useful medicinal potentials and suitable obtained biocompatibility of produced nanoparticles as well as its simplicity, lesser production steps, and cost-effectiveness. Barium carbonate nanostructures were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscope. The toxicity of BACN on U87 brain cancer cells was evaluated based on MTT assay. According to the results, the prepared nanostructures can be employed for biomedical applications, especially cancer therapy.

Cobalt oxide nanoparticles were prepared via green chemistry route and fully characterized by Field Emission Scanning Electron Microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM) and Transmission electron microscopy (TEM) analyses; the CoO and Co3O4 nanoparticles, in sheet-shaped cobalt oxide form, ensued simultaneously in one step. The varying concentrations of NPs were analyzed via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test on the cancer cell line (U87) which revealed that with increasing concentration of cobalt oxide nanoparticles, the survival rate of U87 tumor cells decreases; IC50 of nanoparticles being ~ 55 µg/ml−1.

The development of graphene-based nanocomposites is currently the issue of enormous research interest. Recent advancements have exhibited that semiconductor/graphene nanocomposites can be purposed as a promising new category of catalysts for the heterogeneous photocatalytic treatment of wastewaters. Since semiconductor/graphene nanocomposites have been found efficient in degradation of organic pollutants, photodegradation of phenol and phenolic compounds as hazardous contaminants in aqueous solution has been most widely investigated by these aforementioned nanocomposites. In the present review, after introduction on the properties and the different synthesis methods of semiconductor/graphene nanocomposites, we will discuss the application of these nanocomposites, in fields of photodegradation of phenol and phenolic compounds in aqueous solution.

The novel hybrid adsorbents, which were composed of nanozeolite and nanochitosan (NZ@NCT) and nanozeolite-multi walled carbon nanotube and nanochitosan (CNZ@NCT) were produced by simple method. The adsorption capacity of synthesized nanocomposites towards vanadium (V) was compared with that of a clinoptilolite-nanochitosan nanocomposite (CPL@NCT) obtained from natural zeolite. Zirconium (Zr) was employed to modify prepared nanocomposites because Zr (IV) has a strong affinity towards oxyanions such as V. Zr-modified nanocomposites and their pristine nanocomposites were comparatively characterized by different techniques. Batch experiments were conducted to find out the influence of different experimental factors. The adsorption capacities of all prepared materials towards V ions decreased with temperature increasing from 298 to 348 K. The calculated values of the thermodynamic parameters ΔH and ΔG demonstrated that the adsorption was exothermic and spontaneous. The adsorption process was described by the Freundlich isotherm and pseudo-second order model. The V species loaded nanocomposites could be regenerated by 0.5 M HCl–1.0 M thiourea solution. The adsorption performance was not considerably influenced by the coexistence of the nickel ( Ni2+) but nitrate (NO3−) and sulfate (SO42−) revealed slightly greater negative effects. The as-prepared nanocomposites can be used in three adsorption cycles without specific changing its adsorption efficiency.

Nanotechnology empowered localized cancer chemotherapy has indicated a promising performance for targeting and controlled release of anticancer agents over a period of time to eliminate local-regional recurrence of cancers and also to improve the tissue regeneration during/after treatment. Electrospun nanofiber-based implantable drug-delivery systems have been established as one of the most effective approaches for localized cancer treatment, allowing the on-site delivery of anticancer agents and reducing systemic toxicities and side effects to normal cells. The present review aimed to summarize the latest cutting-edge research on applications of electrospun-based systems for local chemotherapy. Meantime, in vitro and in vivo studies conducted using various anticancer agents along with the capability of electrospun nanofibers for combinatorial/synergistic chemotherapy as well as existing challenges and the potential dramatic advances in applying this pioneering approach for clinical transition in localized treatments of cancer is also discussed.

Greener methods for the synthesis of various nanostructures with well-organized characteristics and biomedical applicability have demonstrated several advantages, including simplicity, low toxicity, cost-effectiveness, and eco-friendliness. Spinel nickel ferrite (NiFe2O4) nanowhiskers with rod-like structures were synthesized using a simple and green method; these nanostructures were evaluated by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, and X-ray energy diffraction spectroscopy. Additionally, the prepared nanowhiskers could significantly reduce the survival of Leishmania major promastigotes, at a concentration of 500 μg/mL; the survival of promastigotes was reduced to ≃ 26%. According to the results obtained from MTT test (in vitro), it can be proposed that further studies should be conducted to evaluate anti-leishmaniasis activity of these types of nanowhiskers in animal models.

Four aluminum flat grooved heat pipes with groove widths of 0.2, 0.4, 0.8 and 1.6 mm are fabricated and the effect of filling ratio on the thermal performance is experimentally studied for four different heat flux values of 2.1, 3.2, 4.2 and 5.3 W / cm 2 . An optimum filling ratio corresponding to each heat flux is determined where the heat pipe has the best thermal performance. Thermal performance of the heat pipes are evaluated using three indicators; (i) the temperature difference between the heat source and heat sink surfaces, (ii) the temperature difference between the peak system temperature and the temperature of the cooling ambient and (iii) heat pipe effectiveness defined as a temperature difference ratio under dry and operating conditions. A flow and evaporative mass scaling model is developed to interpret the experimental findings. Experimental results reveal that at the optimum point the heat pipe with the 0.4 mm groove width has the best thermal performance, and the heat pipe with the smallest 0.2 mm groove operates under dryout conditions even for the lowest heat flux, the reason of which is discussed based on interpretation of underlying phase change physics. Experiments reveal the existence of two operating regimes; with and without dryout in the grooves. Although higher heat loads can be carried under dryout conditions, a limit exists for the maximum heat flux where the pipe operates without the onset of dryout for a specific groove density.

Electrospun nanofibers (NFs)-based drug delivery approaches are of particular interest as a hopeful implantable nanoplatform for localized cancer therapy and treating tissue defect after resection, allowing the on-site drug delivery with minimal side effect to healthy cells. To maintain therapeutic concentrations of anticancer molecules for a relatively long time through a combination of burst and sustained drug release mechanisms, a hybrid of polycaprolactone and gelatin (PCL/GEL) was used for co-encapsulation of free curcumin (CUR) and CUR-loaded mesoporous silica nanoparticles (CUR@MSNs) via electrospinning, resulting in a novel drug-loaded nanofibrous scaffold, CUR/CUR@MSNs-NFs. The as-prepared MSNs and composite NFs were characterized via TGA, FTIR, FE-SEM, TEM, and BET. In vitro release profile of CUR from CUR/CUR@MSNs-NFs was examined, and the in vitro antitumor efficacy against MDA-MB-231 breast cancer cells was also evaluated through MTT, scratch assay, DAPI staining, and real-time PCR. The results disclosed that the smooth, bead-free, and randomly oriented CUR/CUR@MSNs-NFs displayed a combination of initial rapid discharge and sustained release for CUR, which led to higher cytotoxicity, lower migration as well as a more pronounced effect on apoptosis induction than CUR-NFs and CUR@MSNs-NFs. The present study illustrated that the dual drug release mechanisms through MSN/NF-mediated drug delivery systems might have a highly hopeful application as a localized implantable scaffold for potential postoperative breast cancer therapy.

Surface roughness is an important factor in many soil moisture retrieval models. Therefore, any mischaracterization of surface roughness parameters (root mean square height, RMSH, and correlation length, ʅ) may result in unreliable predictions and soil moisture estimations. In many environments, but particularly in agricultural settings, surface roughness parameters may show different behaviours with respect to the orientation or azimuth. Consequently, the relationship between SAR polarimetric variables and surface roughness parameters may vary depending on measurement orientation. Generally, roughness obtained for many SAR-based studies is estimated using pin profilers that may, or may not, be collected with careful attention to orientation to the satellite look angle. In this study, we characterized surface roughness parameters in multi-azimuth mode using a terrestrial laser scanner (TLS). We characterized the surface roughness parameters in different orientations and then examined the sensitivity between polarimetric variables and surface roughness parameters; further, we compared these results to roughness profiles obtained using traditional pin profilers. The results showed that the polarimetric variables were more sensitive to the surface roughness parameters at higher incidence angles (θ). Moreover, when surface roughness measurements were conducted at the look angle of RADARSAT-2, more significant correlations were observed between polarimetric variables and surface roughness parameters. Our results also indicated that TLS can represent more reliable results than pin profiler in the measurement of the surface roughness parameters.

Despite theoretical predictions that graphene should be impermeable to all gases, practical experiments on sealed graphene nanodrums show small leak rates. Thus far, the exact mechanism for this permeation has remained unclear, because different potential leakage pathways have not been studied separately. Here, we demonstrate a sealing method that consists of depositing SiO2 across the edge of suspended multilayer graphene flakes using electron beam-induced deposition. By sealing, leakage along the graphene-SiO2 interface is blocked, which is observed to result in a reduction in permeation rate by a factor of 104. The experiments thus demonstrate that gas flow along the graphene-SiO2 interface tends to dominate the leak rate in unsealed graphene nanodrums. Moreover, the presented sealing method enables the study of intrinsic gas leakage through graphene membranes and can enable hermetic graphene membranes for pressure sensing applications.

This study devoted to developing an efficient adsorbent with the excellent adsorption performance of heavy metals and bacteria capturing. Polyresorcinol@CoFe2O4 was synthesized by one-step hydrothermal reaction followed with doping MnS nanoparticles. The composite was characterized with SEM, TEM, BET, EDX, XRD, zeta potential measurement and Raman spectroscopy. Optimization of effective parameters on heavy metal adsorption, i.e., pH, contact time and adsorbent dosage, was performed with response surface methodology using Box–Behnken design. The sorbent showed good performance for Pb(II), Ag(I) and Cr(VI) removal with convenient magnetic separation operation with an adsorption capacity of 201.2, 118.8 and 46.01 mg g−1, respectively. Results of bacteria capturing showed that using 20 mg of the nanocomposite, more than 98% of bacteria (initial concentration of 1.5 × 108 CFU g−1) can be removed from solution within 10 min.

The purpose of this work is to show the effects of drop impact on the creep-fatigue evolution of solder balls in an electronic device. Finite element method analysis was carried out for evaluation of stress and strain distribution in the solder joints. According to the simulation outcomes, the thermal cycling made an accumulated creep strain in the solder balls. The concentration of creep strain considerably increased with the coupling of drop impact into the thermal cycling. This event was owing to the excessive stress exerted on the samples by drop impacts. The stress analysis also indicated that with the addition of drop impacts into the thermal cycling intensified the stress triaxiality at the interfaces. Moreover, the experimental works were done and determined the elemental heterogeneity phenomenon in the solder joints and crack propagation along the interface.

At the present work, FeCoNiMnV high entropy alloy is successfully synthesized by ball milling and the magnetic properties are evaluated in terms of the structure. In order to study the phase formation of the produced alloy with the variation of milling time, X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) were carried out. According to the structural results, the coexistence of FCC and BCC phases is revealed during the milling process. Furthermore, the σ phase, which enriches with vanadium, is observed in the milled powders by progression of the process. As the magnetic results establish, the obtained powders can be considered as a semi-hard magnetic material based on the shape of hysteresis loops. Moreover, the maximum saturation magnetization of 100 emu/g is observed for the 48 h-milled powder. The magnetic properties are evaluated based on the formation and detection of the various phases in the produced alloy.

Despite numerous theoretical investigations on the mechanical properties of graphene, an accurate identification of its material behavior is still unattained. One hypothesis for this uncertainty is that modeling graphene as a static membrane cannot describe the strong coupling between mechanics and thermodynamics of this structure. Therefore, characterization methods built upon static models could not capture these effects. In this paper, we propose a new method for building a reduced order model for the dynamics of thermalized graphene membranes. We apply the proper orthogonal decomposition algorithm on time responses obtained from molecular dynamics simulations. As a result, a set of orthogonal modes is obtained which are then employed to build a reduced order model. The proposed model can describe the motion of the suspended graphene membrane over the whole spatial domain accurately. Moreover, due to its computational efficiency, it is more versatile for exploring the nonlinear dynamics of the system. This model is then employed for studying the nonlinear dynamics of graphene membranes at large amplitudes to extract Young's modulus. The obtained Young's modulus incorporates the effects of nano-scaled thermally induced dynamic ripples and hence, is temperature and size dependent. Our proposed atomistic modal order reduction method provides a framework for studying the dynamics and extracting the mechanical properties of other nano-structures at the molecular level.

The super-paramagnetic iron oxide nanoparticles (SPIONs) were synthesized using an environmentally friendly method. The SPIONs with mainly carbohydrate coatings were simply synthesized using a natural, zero calorie sweetener (Stevia) extract (as both reducing and stabilizing agents). The resulting SPIONs were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), vibrating-sample magnetometer (VSM) and Zeta potential test. The SPIONs (smaller than 25 nm) are very stable due to bio-molecular coating because having a zeta potential of −41.1 mV creates opposing forces between nanoparticles and prevents them from gathering. The biogenic SPIONs were able to counteract the effects of oxidative metabolites as studied with the antioxidant activity with an IC50 of 65 μg/ml. This feature shows the capability of these nanoparticles in designing potential biomedical applications.

We report the first study on the thermal behavior of the stiffness of individual carbon nanotubes, which is achieved by measuring the resonance frequency of their fundamental mechanical bending modes. We observe a reduction of the Young’s modulus over a large temperature range with a slope −(173±65)ppm/K in its relative shift. These findings are reproduced by two different theoretical models based on the thermal dynamics of the lattice. These results reveal how the measured fundamental bending modes depend on the phonons in the nanotube via the Young’s modulus. An alternative description based on the coupling between the measured mechanical modes and the phonon thermal bath in the Akhiezer limit is discussed., This work is supported by ERC advanced (Grant No. 692876), ERC PoC (Grant No. 862149), Marie Skłodowska-Curie (Grant No. 665884), PROBIST (Grant No. 754510), the Cellex Foundation, the CERCA Programme, AGAUR (Grant No. 2017SGR1664), Severo Ochoa (Grant No. SEV2015-0522), MICINN (Grants No. RTI2018-097953-B-I00 and No. PGC2018-096955-B-C44), the Fondo Europeo de Desarrollo Regional, the Grant No. MAT2017-82970-C2-2-R of Spanish MINECO and the Project No. E13_17R from Aragon Regional Government (Construyendo Europa desde Aragón). F. A. acknowledges support from European Research Council (ERC) starting Grant No. 802093. P. V. acknowledges support from European Research Council (ERC) starting grant 758794 “Q-ROOT.”

Recently, the application of micromixers in microfluidic systems including chemical and biological assays has been widely accomplished. Passive micromixers, benefitting from the low-cost and a less-complex fabrication process, rely solely on their geometry. In particular, Dean vortices generated in curved microchannels enhance the mixing performance through chaotic advection. To improve the mixing performance at relatively low Reynolds numbers (i.e. 1 ≤ Re ≤ 50), this study introduces baffles into the side walls of curved serpentine micromixers with curvature angles of 280°, which constantly agitate, stretch and fold the fluids streams. Six different baffle configurations were designed and the effects of geometry and the number of baffles were investigated both experimentally and numerically. According to the experimental results, while the maximum outlet mixing index of the micromixer with no baffles was 0.61, that of the micromixer with quasi-rectangular baffles was 0.98 at a low Reynolds number of 20, indicating the major contribution of the generated chaotic advection by baffles. Furthermore, numerical results, which were in good agreement with experimental results, shed more light onto the mechanisms involved in micromixing in terms of the flow behavior and mixing index.

An innovative technique, called conversion, is introduced to model circumferential cracks in thin cylindrical shells. The semi-analytical finite element method is applied to investigate the modal deformation of the cylinder. An element including the crack is divided into three sub-elements with four nodes in which the stiffness matrix is enriched. The crack characteristics are included in the finite element method relations through conversion matrices and a rotational spring corresponding to the crack. Conversion matrices obtained by applying continuity conditions at the crack tip are used to transform displacements of the middle nodes to those of the main nodes. Moreover, another technique, called spring set, is represented based on a set of springs to model the crack as a separated element. Components of the stiffness matrix related to the separated element are incorporated while the geometric boundary conditions at the crack tip are satisfied. The effects of the circumferential mode number, the crack depth and the length of the cylinder on the critical buckling load are investigated. Experimental tests, ABAQUS modeling and results from literature are used to verify and validate the results and derived relations. In addition, the crack effect on the natural frequency is examined using the vibration analysis based on the conversion technique., Comment: 23 pages, 12 figures, and 5 tables

The dynamics of suspended two-dimensional (2D) materials has received increasing attention during the last decade, yielding new techniques to study and interpret the physics that governs the motion of atomically thin layers. This has led to insights into the role of thermodynamic and nonlinear effects as well as the mechanisms that govern dissipation and stiffness in these resonators. In this review, we present the current state-of-the-art in the experimental study of the dynamics of 2D membranes. The focus will be both on the experimental measurement techniques and on the interpretation of the physical phenomena exhibited by atomically thin membranes in the linear and nonlinear regimes. We will show that resonant 2D membranes have emerged both as sensitive probes of condensed matter physics in ultrathin layers, and as sensitive elements to monitor small external forces or other changes in the environment. New directions for utilizing suspended 2D membranes for material characterization, thermal transport, and gas interactions will be discussed and we conclude by outlining the challenges and opportunities in this upcoming field., Comment: 39 pages, 16 figures

The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration.on the order of 10 million gs.produced by high-frequency (10 MHz) nanometer-order electromechanical vibrations on a chipscale piezoelectric substrate is capable of efficiently nebulizing, and consequently dimensionally reducing, a suspension of multilayer Ti3C2Tz (MXene) into predominantly monolayer nanosheets and quantum dots while, importantly, preserving the material from any appreciable oxidation. As an example application, we show that the high-purity MXene quantum dots produced using this room-temperature chemical-free synthesis method exhibit superior performance as electrode materials for electrochemical sensing of hydrogen peroxide compared to the highly oxidized samples obtained through conventional hydrothermal synthesis. The ability to detect concentrations as low as 5 nM is a 10-fold improvement to the best reported performance of Ti3C2Tz MXene electrochemical sensors to date. Funding Agencies|Australian Research CouncilAustralian Research Council [DP180102110]; SSF Synergy Program [EM16-0004]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW2015.0043]; ARC DECRA FellowshipAustralian Research Council [DE200100279]; RMIT University

Owing to their atomic thickness and low bending rigidity, suspended two-dimensional (2D) materials are prone to wrinkle formation. Here, we use molecular dynamics (MD) simulations to probe the effect of these wrinkles on the nonlinear elasticity of atomically thin graphene membranes. We observe a stress-strain response that consists of two linear regions that are separated by a transition. It is found that this transition is sharp in membranes where wrinkles are formed by uneven stresses at the boundaries. However, when wrinkles are formed by crystal defects, this nonlinear transition is seen to be more gradual. To capture these effects, we use a phenomenological model based on experimentally measurable quantities. We demonstrate the model's fidelity by fitting it to the MD simulated nonlinear response of many graphene membranes providing evidence that the sharpness of the transition between the linear regions in the stress-strain response is a measure of the type of wrinkles and can be quantified by our model.

Increasing the signal-to-noise ratio in dynamic atomic force microscopy plays a key role in nanomechanical mapping of materials with atomic resolution. In this work, we develop an experimental procedure for increasing the sensitivity of higher harmonics of an atomic-force-microscope cantilever without modifying the cantilever geometry but instead by utilizing dynamical mode coupling between its flexural modes of vibration. We perform experiments on different cantilevers and samples and observe that via nonlinear resonance frequency tuning we can obtain a frequency range where strong modal interactions lead to 7-fold and 16-fold increases in the sensitivity of the 6th and 17th harmonics while reducing sample indentation. We derive a numerical model that captures the observed physics and confirms that nonlinear mode coupling is the reason for the increase of the amplitude of higher harmonics during tip-sample interactions.

The thermal characterization of aluminum flat grooved heat pipes is performed experimentally for different groove dimensions. Three heat pipes with groove widths of 0.2 mm, 0.4 mm, and 1.5 mm are used in the experiments. The effect of the amount of the working fluid is extensively studied for each groove width. The results reveal that, although all three succeed in dissipating the heat input through the phase change of the working fluid by continuous evaporation and condensation, the effectiveness of the heat transfer increases with reduced groove width. Furthermore, it is observed that there exists an optimum operating point, where the temperature difference between the heating and cooling sections is at a minimum, and the magnitude of this temperature difference is a strong function of the groove width. To the best of the authors’ knowledge, the combined effects of groove dimensions and the amount of the working fluid, from fully flooded to dry, is reported for the first time for aluminum flat grooved heat pipes.

This study reports the design and numerical modelling of a microfluidic mixer with an integrated ion-sensitive transistor (ISFET) for sensing of pH values. The valves in the microfluidic device allowed adjustment of the flow rate of each solution and different pH values for the mixture was achieved. At high flow rates around $1500 \mu \mathrm{L} /\min$, pH value of the solution could be controlled in the range of 3-12 with a response time on the order of seconds. The performance of the proposed micromixer in mixing diluted acid and base solutions was simulated using COMSOL Multiphysics software. Current-voltage characteristics were obtained by using silicon dioxide (SiO 2 ) and tantalum pentoxide (Ta 2 O 5 ) as the gate dielectric, and pH sensitivities were compared. Upon optimization of the micromixer and sensor, a numerical model, which included both components was developed by setting the flow rates of diluted acid and base solutions. This enabled active control on the pH of the mixed solution, which was exposed to the ISFET pH sensor at the outlet of the micromixer, where the ISFET sensor continuously monitored the pH of the solution with a separate readout circuit.

In this work, the utilization of TiO2 nanotube (TNT) layers decorated with TiO2 nanoparticles (NPs) as anodes in Li-ion microbatteries is reported for the first time. Such TiO2 NPs decorated TNT layers possess an increased amount of active material and a higher surface area compared with their non-decorated (blank) counterparts. TNT layers decorated with several different amounts of TiO2 NPs were tested by galvanostatic cycling tests. The capacities of the TiO2 NPs decorated TNT layer anodes increase with the amount of NPs decoration due to the enhancement of the capacitive effect. Indeed, an areal capacity of ∼126 μAh cm−2 (vs 88 μAh cm−2 for the non-decorated TNT layer) at the 200th cycle has been obtained after optimizing the NPs loading. On the other hand, a too high NPs loading of the TNT layers leads to a reduced areal capacity due to clogging of the nanotube exteriors and a significant decrease in inner diameter of the nanotubes.

Synthesis and properties of a new zinc oxide nanostructure, and its antimicrobial applications are presented. The synthesis method was fast, clean and green using a natural sweetener (Stevia) extract. The synthesized nanoparticles had a rectangular shape with a size range of 10–90 nm. The antimicrobial activity of the biosynthesized nanoparticles in parasitic strain of Leishmaniasis major and bacterial strains of Staphylococcus aureus and Escherichia coli was studied. It was found that low concentrations of the nanoparticles are required for complete prevention of growth of these organisms in vitro .

Mesoporous diatomite platelets were employed to prepare various random poly (styrene-co-methyl methacrylate)/diatomite composites by in situ simultaneous reverse and normal initiation technique for atom transfer radical random copolymerization (SR&NI ATRP) technique. Nitrogen adsorption/desorption isotherm, SEM and TEM were employed for evaluating some inherent properties of the pristine diatomite platelets. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Addition of 3 wt% diatomite platelets leads to increase of conversion from 76 to 92%. Molecular weight of poly (styrene-co-methyl methacrylate) chains increases from 12893 to 14907 g mol-1 by addition of 3 wt% mesoporous diatomite; however, polydispersity index values increases from 1.18 to 1.44. Copolymers composition was evaluated using 1H NMR spectroscopy. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 67.6 to 73.4 °C by adding 3 wt% of mesoporous diatomite platelets.

Nickel-ferrite (NiFe2O4) nanorods particles (NRP) was biosynthesised for the first time by the Rosemary Extract. The NRP was fully characterised, including the type, nanostructure and physicochemic...

Micromixers are of considerable significance in many microfluidics system applications, from chemical reactions to biological analysis processes. Passive micromixers, which rely solely on their geometry, have the advantages of low cost and a less-complex fabrication process. Dean vortices seen in curved microchannels are one of the useful tools to enhance micromixing. In this study, the effects of curve angle on micromixing were experimentally investigated in three curved serpentine micromixers consisting of ten segments with curve angles of 180 ∘ , 230 ∘ and 280 ∘ , at Dean numbers between 12 and 87. To characterize and compare the performance of the micromixers, fluorescence intensity maps and mixing indices were utilized. Accordingly, the micromixer having segments with 280 ∘ curve angle had significantly higher mixing index values up to the Dean number 60 and outperformed the other two micromixers. This was due to the severe distortion of flow streamlines by Dean vortices and the occurrence of chaotic advection at lower Dean numbers. Beyond the Dean number of 70, no difference was observed in the performance of the micromixers and the mixing index at their outlets had the asymptotic value of 0.93&plusmn, 0.02. Furthermore, the flow behavior of the micromixers was numerically simulated to provide further insight about the mixing phenomena.

Recently, researchers succeeded in designing and manufacturing a new class of nanoparticles (NPs) called hybrid NPs. Among hybrid NPs, bimetallic and core-shell NPs were a revolutionary step in NPs science. A large number of green physiochemical and methods for nanostructures synthesis have been published. Eventually, physiochemical methods are either expensive or require the use of chemical compounds for the synthesis of bimetallic and core-shell nanostructures. The main challenges that scientists are facing are making the process cheaper, facile and eco-friendly efficient synthesis process. Green synthesis (biosynthesis) refers to the use of bio-resources (such as bacteria, fungi, plants or their derivatives) for the synthesis of nanostructures. The popularity of the green synthesis of nanostructures is due to their environmental friendliness and no usage of toxic materials, environmental friendliness for the synthesis or stability of nanostructure. Bimetallic and core-shell NPs have many biomedical applications such as removing heavy metals, parasitology, molecular and microbial sensor, gene carrier, single bacterial detection, oligonucleotide detection and so on. The purpose of this study is to discuss briefly the biosynthesised bimetallic and core-shell NPs, their biomedical applications.

In the field of nanomechanics, parametric excitations are of interest since they can greatly enhance sensing capabilities and eliminate cross-talk. Above a certain threshold of the parametric pump, the mechanical resonator can be brought into parametric resonance. Here we demonstrate parametric resonance of suspended single-layer graphene membranes by an efficient opto-thermal drive that modulates the intrinsic spring constant. With a large amplitude of the optical drive, a record number of 14 mechanical modes can be brought into parametric resonance by modulating a single parameter: the pre-tension. A detailed analysis of the parametric resonance allows us to study nonlinear dynamics and the loss tangent of graphene resonators. It is found that nonlinear damping, of the van der Pol type, is essential to describe the high amplitude parametric resonance response in atomically thin membranes.

TiO2 nanopowders doped by Ni were prepared by sol–gel method. The effects of Ni ion (transition metal ion) doping on the physical structural and optical properties of TiO2 have been investigated by X-ray diffraction (XRD), scanning electron microscopy and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO2. The phase transformation from anatase to rutile was inhibited by Ni ion doped TiO2 at temperatures 675 °C. The lowest band gap value (2.83 eV) was obtained for TiO2-4%Ni sample calcined at 675 °C.

Tailor-made poly(methyl methacrylate)/mesoporous diatomite nanocomposites were synthesized by in situ simultaneous reverse and normal initiation technique for atom transfer radical polymerization (SRN however, polydispersity index values increase from 1.18 to 1.48. Appropriate agreement between theoretical and experimental molecular mass in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 80.6 to 85.9 °C by adding 3 wt% of mesoporous diatomite platelets.

Mesoporous diatomite nanoplatelets were employed to prepare various poly (styrene-co-butyl acrylate)/diatomite nanocomposites by in situ reverse atom transfer radical polymerization of styrene and butyl acrylate. Fourier-transform infrared spectroscopy, thermogravimetric analysis (TGA), and nitrogen adsorption/desorption isotherm were employed for evaluating some properties of the pristine diatomite nanoplatelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Addition of 3 wt% pristine mesoporous diatomite nanoplatelets leads to an increase in conversion from 77% to 92%. Molecular weight of poly (styrene-co-butyl acrylate) chains increases from 17,348 g mol−1 to 21,346 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite nanoplatelets; however, polydispersity index values increases from 1.38 to 1.65. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 35.5°C to 39.4°C with the addition of 3 wt% mesoporous diatomite nanoplatelets.

Water assisted synthesis of high quality and high yield single walled carbon nanotubes (SWCNTs) was performed over Co–Mo/MgO catalyst by chemical vapor deposition (CVD) method. The effect of varying the water amount on the yield and quality of SWCNTs was studied. The as-synthesized SWCMTs were employed for mercury adsorption from aqueous solution. Also, in order to improve the adsorption process, the two magnetite SWCNTs (MSWCNTs) and magnetite SWCNTs–CoS (MSWCNTs–CoS) nanohybrids were prepared. The XRD, TGA, FE-SEM, TEM, Raman, VSM and EDX analysis were carried out to study the effects of water vapor on quality, growth rate and yield of SWCNTs as well as to verify the nanohybrids structures. It was found that with increasing the water/methane up to 8% volume ratio, the quality and yield of nanotubes were reached to their maximum levels. However, more increasing the water vapor up to 20% caused dramatic decreases in the yield and quality. Mercury adsorption properties of SWCNTs, MSWCNTs and MSWCNTs-CoS were studied with the aid of response surface methodology (RSM). Kinetic, isotherm and thermodynamic studies revealed that MSWCNTs–CoS had a very high efficiency for mercury adsorption with a very much low equilibrium time (7 min) indicating its super-adsorbent property.

This study deals with the influence of manufacturing-induced geometric variability on the identification of material properties of composite sandwich panels. The objective of this article is twofold. First, this work aims to demonstrate the marked influence of geometric uncertainties on a foam core sandwich panel whose skin material properties need to be identified. Several identification cases are studied based on experimentally obtained natural frequencies and mode shapes. The second objective is to propose a numerical method for the identification process in the case where uncertainties can be treated as a random field (e.g., thickness distribution). The identification method is built around a classification-based technique referred to as “fidelity maps”, which has the ability to simultaneously treat several responses to match without any assumption on their correlation. The approach uses a proper orthogonal decomposition for the extraction and the selection of the features of the random field considered as important for the identification. The identification method is demonstrated on a foam core sandwich panel whose thickness distribution is modeled as a random field.

Diamagnetic levitation offers stable confinement of an object from its environment at zero power, and thus is a promising technique for developing next generation unclamped resonant sensors. In this work, we realize a resonant weighing scale using a graphite plate that is diamagnetically levitating over a checkerboard arrangement of permanent magnets. We characterize the bending vibrations of the levitating object using laser Doppler vibrometry and use microgram glass beads to calibrate the responsivity of the sensor's resonance frequency to mass changes. The sensor is used for real-time measurement of the evaporation rate of nano-litre droplets with high-accuracy. By analyzing the resonator's frequency stability, we show that the millimeter graphite sensor can reach mass resolutions down to 4.0ng, relevant to biological and chemical sensing concepts., Comment: 16 pages, 8 figures

This paper presents an analytical method to investigate the propagation characteristics of a uniform microstrip line placed on porous substrates. The structure is periodic with a specified unit cell and the substrate is made of cascaded multi-layer dielectric slabs. The proposed method is started by solving wave equation by decomposing Helmholtz operator using appropriate eigen-functions and applying the associated boundary conditions of tangential electromagnetic fields of the unit cell. Then, using Floquet theorem, the equivalent propagation constant of a one-dimensional (1-D) periodic structure is obtained. In addition to, the proposed method is developed for two-dimensional (2-D) structures by a suitable transformation. Several practical structures are considered to verify the accuracy of the proposed method. The comparison of the proposed analytical model and measurement results and those obtained using simulation process provided by High Frequency Simulator Strctures (HFSS) are reported. It is shown that our method can be used for a wide variety of structures to quickly estimate the required parameters with a good accuracy.

In the last two decades, anodic TiO2 nanotube (TNT) layers have gained considerable attention for both their unique physical and chemical properties practical applications [1-3]. One of the key parameters that characterize TNT layers is the aspect ratio, which is the ratio between the TNT layer thickness and the nanotube diameter. In particular, TNT layers with a high aspect ratio (HAR) due to their 1D ordered structure, an exceptional morphology and a high surface area, have a great potential in different applications, such as filtration and micro-photo reactors [4,5]. In the last decade, ethylene glycol (EG)-based electrolytes containing small amounts of NH4F and H2O [6] were the most widely used electrolytes to produce high-aspect ratio TNT layers. However, using these electrolytes very long anodization times i.e., several hours or up to several days [7], are needed. Apparently, the synthesis of long and extremely robust HAR TNT layers in a relatively short time remains very challenging until now. Recently, it has been shown that the addition of lactic acid (LA) to EG-based electrolytes can shift the dielectric breakdown potential to significantly higher potentials due to the strong adsorption of lactic acid on TiO2 during the anodization [8]. Thus, considerably higher anodization potentials and increased electrolyte temperatures can be employed and HAR TNT layers can be obtained within less than one hour of anodization. In this presentation we will demonstrate that HAR TNT layers can be obtained within short anodization times using an optimized anodization protocol. The key feature is the use of NH4F/H2O/EG electrolytes containing LA with optimized electrolyte [9]. Experimental details and some recent anodization results will be presented and discussed. References: [1] J.M. Macak et al., small. 2007, 300-304,3. [2] J.M. Macak et al., Curr. Opin. Solid State Mater. 2007, 3-8,11. [3] R. Poulomi, et al., Nanoscale. 2010, 45-59, 2. [4] G. Cha, et al., Electrochim. Acta 2020, 302-310, 258. [5] Z. Xuemei, et al., ACS Catalysis 2017, 3210-3235, 7. [6] K. Lee et al., Chem. Rev. 2014, 9385-9454, 114. [7] S.P. Albu et al., Phys. Status Solidi RRL. 2007 R65-R67, 1. [8] S. So et al., J. Am. Chem. Soc. 2012, 11316-11318, 134. [9] M. Alijani et al., Electrochim. Acta 2020, submitted.

We report the changes in the structural and optical property of TiO2 nanoparticles on co-doping Sn and Co ions. Different amounts of Co and Sn co-doped TiO2 (with 1–2–4 mol% Co and 1–5–10 mol% Sn) powders were prepared at temperatures in the range of 475 and 875 °C by simple sol–gel synthesis technique and were thoroughly characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope, fourier-transform infrared, Brunauer, Emmett and Teller (BET) surface area, zeta potential and flat band potential measurements. Photo-catalytic ability of co-doped TiO2 powders was evaluated by means of methylene blue degradation experiments conducted under the irradiation of simulated solar light. The XRD showed the presence of only anatase TiO2 for the un-doped and Co-doped titania samples. Titania rutile phase formation in nanoparticles was promoted by Sn4+ addition. XRD analysis also pointed out the decrease in the crystal size with the increase in Sn concentration in the samples. The BET analysis reported an increase in the surface area with the increase in the Sn concentration. It was found that the photo-catalytic activity of TiO2 was obviously enhanced by the co-doping. The excellent photo-catalytic activities due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photo-catalytic oxidizing species with the doping of Co and Sn in TiO2.

An efficient adsorption system was developed for removal of hazardous Direct Blue 71 as a sample azo dye. The γ-Fe2O3@CuO adsorption system was synthesized based on a sol–gel combustion route and characterized by energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) analysis, vibrating-sample magnetometry (VSM), and field-emission scanning electron microscopy (FESEM) techniques. The response surface methodology with Box–Behnken design was used to evaluate the effects of pH, shaking time, and adsorbent dose on dye adsorption. The results showed that solution pH was the parameter with greatest effect on dye adsorption. Adsorption equilibrium was reached quickly, within 8 min. Study of isotherms revealed adsorption capacity of 45.7 mg g−1 according to the Freundlich model. Sorbent regeneration could be performed using methanol–NaOH (0.1 mol L−1) solution.