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The main aim of this paper is to create nanoporouse aluminium oxide membrane which could be used as vibroactive nanofilter in biomedical micro hydraulic devices. This research paper covers the experimental setup of nanoporouse aluminium oxide membrane fabrication and the investigations of its chemical and surface properties. A custom-made anodization experimental setup was used to form membrane with hexagonal pores of 70 nm diameter and 110 nm interpore distance. [ABSTRACT FROM AUTHOR]

With increasing technical requirements in the design of microresonators, the development of new techniques for lightweight, simple, and inexpensive components becomes relevant. Lead zirconate titanate (PZT) is a powerful tool in the formation of these components, allowing a self-actuation or self-sensing capability. Different fabrication methods lead to the variation of the properties of the device itself. This research paper covers the fabrication of a novel PZT film and the investigations of its chemical, surface, and dynamic properties when film thickness is varied. A screen-printing technique was used for the formation of smooth films of 60 μm, 68 μm, and 25 μm thickness. A custom-made poling technique was applied to enhance the piezoelectric properties of the designed films. However, poling did not change any compositional or surface characteristics of the films; changes were only seen in the electrical ones. The results showed that a thinner poled PZT film having a chemical composition with the highest amount of copper and zirconium led to better electrical characteristics (generated voltage of 3.5 mV). [ABSTRACT FROM AUTHOR]

A novel cantilever type piezoelectric sensing element was developed. Cost-effective and simple fabrication design allows the use of this element for various applications in the areas of biomedicine, pharmacy, environmental analysis and biosensing. This paper proposes a novel piezoelectric composite material whose basic element is PZT and a sensing platform where this material was integrated. Results showed that a designed novel cantilever-type element is able to generate a voltage of up to 80 μV at 50 Hz frequency. To use this element for sensing purposes, a four micron periodical microstructure was imprinted. Silver nanoparticles were precipitated on the grating to increase the sensitivity of the designed element, i.e., Surface Plasmon Resonance (SPR) effect appears in the element. To tackle some issues (a lack of sensitivity, signal delays) the element must have certain electronic and optical properties. One possible solution, proposed in this paper, is a combination of piezoelectricity and SPR in a single element. [ABSTRACT FROM AUTHOR]

This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4-4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation. [ABSTRACT FROM AUTHOR]

This research suggests employing electrode segmentation in order to avoid charge cancellation in the piezoelectric layers of harvester, which occurs, if strain nodes of vibrating harvester are covered by continuous electrodes. Two types of piezoelectric energy harvester prototypes were produced from piezoelectric plate, epoxy bonded to stainless steel substrate for experimental investigations. The first (reference) harvester prototype posses no electrode segmentation, while electrodes covering piezoelectric material of second harvester were segmented. Segmentation of the second harvester was configured for its operation at the second resonant frequency -- i.e., performed so, that the electrodes of piezoelectric layer are not covering strain node of the second vibration mode. Experimental results revealed that segmented harvester prototype posses efficiency advantage as compared to the non-segmented counterpart -- adding voltages, generated at each segment would result from 16 % to 60 % increase of maximum generated voltage. Also conception, that using stopper, placed at appropriate position, energy harvesting process could be stabilized, i.e. bandwidth of operating frequency could be increased. [ABSTRACT FROM AUTHOR]

This text investigates the bending/buckling behavior of multi-layer asymmetric/symmetric annular and circular graphene plates through the application of the nonlocal strain gradient model. Additionally, the static analysis of multi-sector nanoplates is addressed. By considering the van der Waals interactions among the layers, the higher-order shear deformation theory (HSDT), and the nonlocal strain gradient theory, the equilibrium equations are formulated in terms of generalized displacements and rotations. The mathematical nonlinear equations are solved utilizing either the semi-analytical polynomial method (SAPM) and the differential quadrature method (DQM). Also, the available references are used to validate the results. Investigations are conducted to examine the effect of small-scale factors, the van der Waals interaction value among the layers, boundary conditions, and geometric factors. [ABSTRACT FROM AUTHOR]

Modern day industries are highly focused on the development of bio-inspired hybrid natural fiber composites for lightweight biosensor chips, automobile, and microfluidic applications. In the present research, the mechanical properties and morphological characteristics of alkaline (NaOH)-treated hemp, flax, noil hemp, and noil flax fiber-reinforced ecopoxy biocomposites were investigated. The samples were fabricated by employing the hand layup technique followed by the compression molding process. A total of two sets of composites with various weight fractions were fabricated. The samples were tested for mechanical properties such as flexural strength, interlaminar shear strength, moisture absorption, and contact angle measurement. The treated fibers were analyzed by using an optical microscope and Fourier transform infrared spectrometer (FTIR). The morphological characteristics, such as porosity and fracture mechanisms, were investigated by using scanning electron microscopy and SEM−EDX spectroscopy. The results revealed that the flexural properties of hybrid composites vary from 22.62 MPa to 30.04 MPa for hemp and flax fibers and 21.86 MPa to 24.70 MPa for noil fibers, whereas in individual fiber composites, the strength varies from 17.11 MPa to 21.54 MPa for hemp and flax fibers and 15.83 MPa to 18.79 MPa for noil fibers. A similar trend was observed in interlaminar shear properties in both cases. From moisture analysis, the rate of absorption is increased with time up to 144 h and remains constant in both cases. The moisture gain was observed more in individual composites than hybrid composites in both cases. Hence, the impact of hybridization was observed clearly in both cases. Also, hybrid composites showed improved properties compared to individual fiber composites. [ABSTRACT FROM AUTHOR]

A concept of a nanoporous anodic aluminum oxide (AAO) membrane as a vibro-active micro/nano-filter in a micro hydro mechanical system for the filtration, separation, and manipulation of bioparticles is reported in this paper. For the fabrication of a nanoporous AAO, a two-step mild anodization (MA) and hard anodization (HA) technique was used. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to analyze the surface morphology of nanoporous AAO. A nanoporous structure with a pore diameter in the range of 50–90 nm, an interpore distance of 110 nm, and an oxide layer thickness of 0.12 mm with 60.72% porosity was obtained. Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) were employed to evaluate AAO chemical properties. The obtained results showed that the AAO structure is of hexagonal symmetry and showed where Al2O3 is dominant. The hydrophobic properties of the nanoporous surface were characterized by water contact angle measurement. It was observed that the surface of the nanoporous AAO membrane is hydrophilic. Furthermore, to determine whether a nanomembrane could function as a vibro-active nano filter, a numerical simulation was performed using COMSOL Multiphysics 5.4 (COMSOL Inc, Stockholm, Sweden). Here, a membrane was excited at a frequency range of 0–100 kHz for surface acoustics wave (SAW) distribution on the surface of the nanoporous AAO using a PZT 5H cylinder (Piezo Hannas, Wuhan, China). The SAW, standing acoustic waves, and travelling acoustic waves of different wavelengths were excited to the fabricated AAO membrane and the results were compared with experimental ones, obtained from non-destructive testing method 3D scanning vibrometer (PSV-500-3D-HV, Polytec GmbH, Waldbronn, Germany) and holographic interferometry system (PRISM, Hy-Tech Forming Systems (USA), Phoenix, AZ, USA). Finally, a simulation of a single nanotube was performed to analyze the acoustic pressure distribution and time, needed to center nanoparticles in the nanotube. [ABSTRACT FROM AUTHOR]

This paper reviews recent investigations and achievements in the design of controllable functional components for improving microfluidic systems, its effectiveness, and functionality. The main purpose was to design novel microstructures with piezoelectric properties (microresonators), which enable one to control the effectiveness of fluid flow in micro-hydro-mechanical devices for biomedical/biochemical purposes. Controllable properties were obtained by incorporating different types of binders in a piezoelectric ceramic matrix (lead zirconate titanate): polyvinyl butyral (PVB), poly methyl methacrylate (PMMA), and polystyrene (PS). The change in chemical composition of PZT helps to manipulate the piezoelectric characteristics, surface morphology, mechanical properties, etc., of the designed microfluidic element with the microstructure in it. [ABSTRACT FROM AUTHOR]

The paper is dedicated to analysis, practical exploitation of sonotrode, whose fundament is multilayer actuator in experiments of mechanical hot imprint. The goal is to compare the quality of microstructures, created by using vibration based on multilayer actuator. Numerical modelling and experimental analysis is performed in order to find resonant frequency of the sonotrode. Having operating frequency, sonotrode applied in mechanical hot imprint process. Microstructures are created on the surface of polycarbonate; the only process variable is vibration. Two types of microstructure quality measurements are performed: measurement of diffraction efficiency, optical microscopy in order to examine quality of replica. [ABSTRACT FROM AUTHOR]

Corrosion is a harmful processes which by definition is a chemical or electrochemical reaction between a substance (usually a metal) and the environment which leads to a change in the properties of the substance and has destructive effects. In this study, new composites consisting of Al/WS2/ZnTerp-2TH with 5 and 10 wt.% ZnTerp-2TH were prepared and the results were fully compared. Al/WS2 played the role of matrix and ZnTerp-2TH played the role of reinforcement. In other words, as a novelty to prevent the corrosion of Al/WS2, ZnTerp-2TH is designed and synthesized and showed good results when the corrosion ratio was reduced by the existence of ZnTerp-2TH. Furthermore, the NMR and mass analysis of ZnTerp-2TH were carried out, and the thermal properties, X-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy, morphology, energy-dispersive X-ray spectroscopy (EDX) analysis and corrosion behavior of the composites were also discussed in detail. The crystal size values of composites were calculated by the modified Scherrer method 34, 26 and 27 nm for Al/WS2, Al/WS2/5 wt.% ZnTerp-2TH and Al/WS2/10 wt.% ZnTerp-2TH, respectively. The microstructural examination of the specimens showed that the reinforcing phase (ZnTerp-2TH) has a favorable distribution on the surface of Al/WS2 when it covers the cracks and holes. In addition, the corrosion investigation results showed that the addition of ZnTerp-2TH to Al/WS2 can improve the corrosion resistance when the Ecorr and Icorr values of Al/WS2/10 wt.% ZnTerp-2TH were recorded in tandem −724 mV/decade and 5 uA cm−2. [ABSTRACT FROM AUTHOR]

In this study, new composites based on polyvinylidene fluoride (PVDF) were ornamented and prepared with hydroxyapatite (HA) and silver nitride (AgNO3). Taking into account the polarity of the solvent dimethyl sulfoxide, this solvent was used to disperse the particles. The aim of using DMSO was to create amorphous phases and the strong dipoles of the C–F bond to reduce the energy barrier and improve the electrical properties. The PVDF played the role of matrix in HA, and AgNO3 was used as reinforcing elements. X-ray diffraction of the samples directly showed the amorphous phase and mixed amorphous and crystalline phases when all three materials were used simultaneously for preparing the composite. The scanning electron microscopy (SEM) images of the samples confirmed the role of PVDF, HA, and AgNO3. Furthermore, the energy dispersive X-ray (EDX) analysis was performed and proved that the HA structure did not change when the ratio of Ca P was equal to the ratio of natural HA. The electrical properties were investigated, and the amount of energy ranged from 56.50 to 125.20 mV. The final results showed that a designed device consisting of an active layer made of 0.1 g HA:0.5 g PVDF showed the highest energy barrier, the highest polarity, and surface energy, thus proving its relevance as potential material for energy harvesting applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel nanocrystalline composite material of hydroxyapatite (HA)/polyvinyltrimethoxysilane (PVTMS)/iron(II)chloride tetrahydrate (Cl2FeH8-O4) with hexagonal structure is proposed for the fabrication of a gas/temperature sensor. Taking into account the sensitivity of HA to high temperatures, to prevent the collapse and breakdown of bonds and the leakage of volatiles without damaging the composite structure, a freeze-drying machine is designed and fabricated. X-ray diffraction, FTIR, SEM, EDAX, TEM, absorption and photoluminescence analyses of composite are studied. XRD is used to confirm the material structure and the crystallite size of the composite is calculated by the Monshi–Scherrer method, and a value of 81.60 ± 0.06 nm is obtained. The influence of the oxygen environment on the absorption and photoluminescence measurements of the composite and the influence of vaporized ethanol, N2 and CO on the SiO2/composite/Ag sensor device are investigated. The sensor with a 30 nm-thick layer of composite shows the highest response to vaporized ethanol, N2 and ambient CO. Overall, the composite and sensor exhibit a good selectivity to oxygen, vaporized ethanol, N2 and CO environments. [ABSTRACT FROM AUTHOR]

Nanoporous anodic aluminum oxide (AAO) is needed for a variety of purposes due to its unique properties, including high hardness, thermal stability, large surface area, and light weight. Nevertheless, the use of AAO in different applications is limited because of its brittleness. A new design of an electrochemical reactor with a vibrating element for AAO nanoporous membranes fabrication is proposed. The vibrating element in the form of a piezoceramic ring was installed inside the developed reactor, which allows to create a high-frequency excitation. Furthermore, mixing and vibration simulations in the novel reactor were carried out using ANSYS 17 and COMSOL Multiphysics 5.4 software, respectively. By theoretical calculations, the possibility to excite the vibrations of five resonant modes at different frequencies in the AAO membrane was shown. The theoretical results were experimentally confirmed. Five vibration modes at close to the theoretical frequencies were obtained in the novel reactor. Moreover, nanoporous AAO membranes were synthesized. The novel aluminum anodization technology results in AAO membranes with 82.6 ± 10 nm pore diameters and 43% porosity at 3.1 kHz frequency excitation and AAO membranes with 86.1 ± 10 nm pore diameters and 46% porosity at 4.1 kHz frequency excitation. Furthermore, the chemical composition of the membrane remained unchanged, and the hardness decreased. Nanoporous AAO has become less brittle but hard enough to be used for template synthesis. [ABSTRACT FROM AUTHOR]

Mg-based alloys have several suitable properties for biomaterials, but they have major problems of being less antibacterial and have a low mechanical strength. To solve these problems, a new combination of Ag/Zn/Mg was prepared in this study, where the presence of Zn and Ag can help to increase the bioactivity. The use of 5 wt.% polymers consisting of PolyCaproLactone (PCL), PolyHydroxyButyrate (PHB) and PolyVinylTriMethoxySilane (PVTMS) is also investigated. DSC, XRD, TEM, FTIR, SEM, and EDAX analysis, as well as mechanical and bioactive behavior, were investigated to characterize the prepared composites. In the comparison, the best behavior was found when PHB was used. The results show that the strength values ranged from ~201 to 261 MPa. [ABSTRACT FROM AUTHOR]

The impact of matrix material on the mechanical properties of natural-fiber-reinforced hybrid composites was studied by comparing their experimental, and numerical analysis results. In the present work hemp and flax fibers were used as reinforcement and epoxy resin and ecopoxy resin along with hardener were used as matrix materials. To study the influence of the matrix material, two sets of hybrid composites were fabricated by varying the matrix material. The composite samples were fabricated by using the compression-molding technique followed by a hand layup process. A total of five different composites were fabricated by varying the weight fraction of fiber material in each set based on the rule of the hybridization process. After fabrication, the mechanical properties of the composite samples were tested and morphological studies were analyzed by using SEM-EDX analysis. The flexural-test fractured specimens were analyzed by using a scanning electron microscope (SEM). In addition, theoretical analysis of the elastic properties of hybrid composites was carried out by using the Halpin–Tsai approach. The results showed that the hybrid composites had superior properties to individual fiber composites. Overall, epoxy resin matrix composites exhibited superior properties to ecopoxy matrix composites. [ABSTRACT FROM AUTHOR]

One important key to improve OLEDs technology is the development and synthesis of high triplet energy host materials, which play a crucial role in improving the efficiency and lifetime. The present approach shows that it is possible to control the properties of the host materials by carefully selecting the units. Therefore, a hexahydroacridine derivative was chosen to increase the E T value due to lower conjugation. In this study, three hosts with high triplet energy (>3 eV) were designed and investigated based on hexahydroacridine (ACD) as a constant unit and branches of triphenylamine (TPA), pyrene and pyridine derivatives as different groups. Density functional theory (DFT) calculations showed the agreement of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) values with the experimental results, with the highest HOMO from DFT calculation at 5.95 eV and cyclic voltammetry (CV) at 6.09 eV for the ACD-PYRIDINE. The photophysical properties were fully discussed and revealed the fluorescence mechanism of the hosts, so that with the addition of 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-N3, N3, N6, N6-tetraphenyl-9H-carbazole-3,6-diamine (DACT-II), thermally activated delayed fluorescence (TADF) was achieved in the emitter layer with different concentrations of the hosts of 50, 70 and 90 wt%. The promising synthesized hosts were used for the fabrication of green TADF OLEDs. The fabricated OLED based on 90 % wt. ACD-TPA had CIE coordinates X = 0.26385 and Y = 0.55236, with turn on voltage 3.5 V, as well as current efficiency (CE), power efficiency (PE) and external quantum efficiency (EQE) of 40 cd A−1, 26 lm.W−1 and 13 %, respectively. Furthermore, the extracted brightness (52508 cd m−2) exceeded the values from previous studies based on acridine as an emitter layer in doped OLEDs. [Display omitted] • Hosts with high triplet (E T > 3 eV) based on hexahydroacridine derivative was designed and synthesized. • The maximum μ hole was calculated to be 1.20 × 10−3 cm2 V−1 s−1 using the SCLC method at an electric field of 920 V cm−1. • ACD-TPA showed the sensing property when the PL spectra covered almost the whole visible region under the N 2 injection. • The maximum luminescence was reached at 52508 cd m−2. • Doped OLEDs containing 90 % wt. ACD-TPA exhibited the highest EQE of 13 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel naphthalimide sulfonylphenyl derivative was designed and synthesized as a host. • For the FL, PH and TTA mechanisms, decay lifetime increased with decreasing temperature. • For the TADF mechanism, the decay lifetime increased with increasing temperature. • Two values of slope were obtained for TTA mechanism when measuring power dependence. • The OLED with TADF emitter had the highest EQE compared to other OLEDs. One of the biggest challenges in the field of optoelectronics is to easily identify the mechanisms involved in light-emitting materials. There are several different mechanisms of emission, and the best known are fluorescence (FL), phosphorescence (PH), thermally activated delayed fluorescence (TADF), and triplet–triplet annihilation (TTA). In this study, simple ways to diagnose these mechanisms are presented with an example. N,N-di(benzenesulfonylphenyl)-N-(N-2-aminomethylpyridine-1,8-naphthalimide)amine is synthesized as a host compound due to its high HOMO-LUMO and ionization potential (IP) values and three emitters consisting of 50 wt% Bis (1phenylisoquinoline))(acetylacetonate)iridium(III) (Ir(piq) 2 (acac)), 10-(4-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (DMAC-TRZ) and 1,1′-(2,5-Dimethyl-1,4-phenylene)dipyrene (DMPPP) were considered. Overall, the host compound, doped Ir(piq) 2 (acac) and doped DMPPP follow the mechanisms of FL, the combination of FL and PH, and the combination of FL and TTA, as the photoluminescence (PL) decay life time and the PL intensity increased with decreasing temperature. However, DMAC-TRZ doped with the host compound showed the TADF mechanism, as the PL decay lifetime and the PL intensity increase simultaneously with increasing temperature. In addition, the difference between the singlet excited state (S 1) and the triplet excited state T 1 (ΔE ST) from the PL and PH spectra at 77 K for the spin-coated DMAC-TRZ-doped host show the lowest value in between the samples at 0.02 eV, and the reverse intersystem crossing (rISC) effect is activated. Moreover, the linear slopes of the power dependence analysis of the DMPPP-doped host were calculated to be 2.04 and 0.91, indicating that there are two components (photons) for this sample which is strong evidence for the TTA mechanism. Taking into account the synthesized host compound, (Ir(piq) 2 (acac):host), (DMAC-TRZ:host) and (DMPPP:host) as emitter layers, the organic light emitting diodes (OLEDs) were fabricated via solution processing, and the TADF OLED exhibited the highest efficiency among the other OLEDs. [ABSTRACT FROM AUTHOR]

The concept of active microchannel for precise manipulation of particles in biomedicine is reported in this paper. A novel vibration-assisted thermal imprint method is proposed for effective formation of a microchannel network in the nanocomposite piezo polymer layer. In this method, bulk acoustic waves of different wavelengths excited in an imprinted microstructure enable it to function in trapping–patterning, valve, or free particle passing modes. Acoustic waves are excited using a special pattern of electrodes formed on its top surface and a single electric ground electrode formed on the bottom surface. To develop the microchannel, we first started with lead zirconate titanate (PZT) nanopowder [Pb (Zrx, Ti1−x) O3] synthesis. The PZT was further mixed with three different binding materials—polyvinyl butyral (PVB), poly(methyl methacrylate) (PMMA), and polystyrene (PS)—in benzyl alcohol to prepare a screen-printing paste. Then, using conventional screen printing techniques, three types of PZT coatings on copper foil substrates were obtained. To improve the voltage characteristics, the coatings were polarized. Their structural and chemical composition was analyzed using scanning electron microscope (SEM), while the mechanical and electrical characteristics were determined using the COMSOL Multiphysics model with experimentally obtained parameters of periodic response of the layered copper foil structure. The hydrophobic properties of the PZT composite were analyzed by measuring the contact angle between the distilled water drop and the three different polymer composites: PZT with PVB, PZT with PMMA, and PZT with PS. Finally, the behavior of the microchannel formed in the nanocomposite piezo polymer was simulated by applying electrical excitation signal on the pattern of electrodes and then analyzed experimentally using holographic interferometry. Wave-shaped vibration forms of the microchannel were obtained, thereby enabling particle manipulation. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose a novel structure glucose sensor which makes glucose level measurement system more convenient, increases measurement accuracy and gets the sensor that can be manufactured applying cheap manufacture processes. The main focus is made on the design of viscoelastic cantilever type sensors with the embedded piezo-active functional element to drive micro cantilever in order to detect concentration of glucose in the physiological liquid. Analytical, numerical and experimental methods for design and analysis of viscoelastic sensor are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • AIE persulfurated benzene derivatives were designed and synthesized. • The crystallite size was reached to be 100.07 nm. • The temperature dependence of the carrier mobility at 298 K and 77 K was studied. • A higher value of hole mobility of 7.50 × 10-4 c m 2 V s was obtained at an electric field of 900 V 0.5 c m 0.5 . In this research, two persulfurated benzene molecules consisting of amine and carboxylic acid derivatives were designed, synthesized and the effect of substitution in para position on absorption, fluorescence, and aggregation induced emission (AIE) were investigated. Moreover, taking into account the simpler method, the space charge limited current (SCLC) was considered and the temperature dependence on carrier mobility (μ) of the derivatives was investigated. The maximum value of hole mobility (μ h) at 298 K was calculated to be 7.50 × 10-4 c m 2 V s at an electric field of 900 V 0.5 c m 0.5 . Since the crystallite size of the compound consisting of the NH 2 group was higher (100.07 nm), the (μ) at 298 K and 77 K were also higher than the other counterpart. As a result, the NH 2 substitution played a more effective role in increasing the (μ). [ABSTRACT FROM AUTHOR]

This paper proposes an approach for designing an efficient vibration energy harvester based on a vibro-impacting piezoelectric microcantilever with a geometric shape that has been rationally modified in accordance with results of dynamic optimization. The design goal is to increase the amplitudes of higher-order vibration modes induced during the vibro-impact response of the piezoelectric transducer, thereby providing a means to improve the energy conversion efficiency and power output. A rational configuration of the energy harvester is proposed and it is demonstrated that the new design retains essential modal characteristics of the optimal microcantilever structures, further providing the added benefit of less costly fabrication. The effects of structural dynamics associated with advantageous exploitation of higher vibration modes are analyzed experimentally by means of laser vibrometry as well as numerically via transient simulations of microcantilever response to random excitation. Electrical characterization results indicate that the proposed harvester outperforms its conventional counterpart (based on the microcantilever of the constant cross-section) in terms of generated electrical output. Reported results may serve for the development of impact-type micropower generators with harvesting performance that is enhanced by virtue of self-excitation of large intensity higher-order mode responses when the piezoelectric transducer is subjected to relatively low-frequency excitation with strongly variable vibration magnitudes. [ABSTRACT FROM AUTHOR]

• Dyes based on acceptor-phenyl-donor were designed and synthesized. • The highest photoluminescence quantum yield of coated dyes on the solid film was 33%. • The highest value for ionization potential from electron photoemission was found to be −5.45 eV. • The dyes were mechanochromic as they change color under the force of 0.5 GPa. Considering the simple peripheral methoxy or/and tert‑butyl substitution at 3,6-position of carbazole and the phenyl ring as a bridge to increase the electron-donor property, emission colors of acceptor-phenyl-donor type (A-Ph-D) of dyes were designed. In this study, two dyes based on groups comprising [1-(9-bromoanthracene)-4-(3‑methoxy-9H-carbazole-9-yl]phenyl and [1-(9-bromoanthracene)-4-(3,6-di‑tert‑butyl‑9H-carba-zole-9-yl]phenyl were synthesized. The density functional theory (DFT) was evaluated and the separate distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was observed. Besides, the photophysical properties of dyes showed the maximum absorption spectra (ABS) at 295 and 299 nm for the spin-coated dyes on the solid film. The photoluminescence spectra (PL) for the emitters revealed the blue and cyan light hues. Additionally, the mechanochromic characteristics, aggregation-induced emission enhancement (AIEE), and thermal stability were also investigated. Our approach resulted in coated dyes on the films with suitable values of ionization potential -5.31 and -5.45 eV in tandem. Moreover, the photoluminescence quantum yields (PLQYs) of the two spin-coated dyes are above 24 and 33%. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanocomposites consisting of TiO 2 -Ag-Ce with different stoichiometric ratio were synthesized by sol–gel method. • Doped Ce was lead to the control of the crystal size. • The size of nanocomposites was achieved to <100 nm. • The best degradation efficiency was obtained for the composite 85%TiO 2 -5%Ag-10%Ce. In this study, nanocomposites consisting of TiO 2 -Ag-Ce with stoichiometric ratio of 1, 3 and 5 wt% Ag and 10 wt% Ce (constant) as photocatalyst were prepared and investigated. Based on the crystallite phase, the thermal calcination temperature was set at 500 °C. X-ray diffraction, FE-SEM, EDS analysis, TEM and FTIR were used to characterize the synthesized powders. The obtained results showed that most of the samples exhibited anatase phase and crystallite size was < 100 nm. Taking into account the photocatalytic properties of nanocomposites on the methylene blue (C 37 H 27 N 3 Na 2 O 9 S 3), the results showed that nanocomposites with 5 wt% Ag and a pollutant model concentration of 10 ppm at PH = 9 exhibited 82 ± 1% destruction of the pollutant, giving the best performance as nanocatalysts. Moreover, the kinetic result of the photocatalyst was in agreement with the destruction result, while the rate constant was the lowest value. [ABSTRACT FROM AUTHOR]

[Display omitted] • Some new fluorescent azo-pyrazole-sulfonamide hybrids have been synthesized. • According to the values of universal index of electrophilicity (ω), the dye 5d has the highest ω. • The values of ionization potential from photoelectron emission spectrometry are in the range from 5.58 to 6.07 eV. • The highest photocurrent is obtained for individual DSSC based on dye with –NO2 group. In this study, we have designed and investigated four new low-emitting fluorescent dyes consisting of sulfonamide derivatives with substitution groups in the LUMO moiety. In these dyes, sulfonamide linked with pyrazole group played an important role in complementing the acceptor moieties. The optical properties of dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay time analysis in the non-doped solid film. The strong effect of substitution by –NO 2 group was impressive, when, the dyes ionization potential photon energy values reached to 5.58, 5.82, 5.83 and 6.07 eV. According to X-ray diffraction, dyes were not amorphous and value of crystallite size was ∼100 nm. The dyes have a promising application as a hole layer in dye sensitized solar cells (DSSCs), due to the separation distribution of HOMO-LUMO, thermal stability, small crystal size, high PLQY, high optical band gap and high electron affinity. Finally, the DSSCs devices were fabricated based on the synthesized dyes and the results showed that the efficiency of the DSSCs based on a dye with –NO 2 group is higher (3.27%) than that of the other dyes. [ABSTRACT FROM AUTHOR]

Two dyes containing of thioxanthenone derivative as an acceptor unit, were designed and synthesized for thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs). The photoluminescence (PL) spectra of hammered dyes were shifted and the dyes were mechanochromic. Ionization potential (IP) values of spin-coated dyes on the fluorine-tin oxide film ranged from −5.42 to −5.49 eV and the hole mobility values reached to 2.64 × 10−4 and 3.56 × 10−4 cm2 V−1s−1. Considering the higher values of the photoluminescence quantum yields (PLQYs) of spin-coated dyes on the solid films (16, 21%) that dispersed the dyes in a solution such as toluene (7, 3%), the aggregation induced emission enhancement (AIEE) phenomena were observed. In addition, the doped devices were fabricated based on 50 wt% poly (9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB) as a host material through the solution process and physically evaporation deposition (PVD). In this study, the effect of utilizing 4, 4′, 4″-Tris [(3-methylphenyl) phenylamino]triphenylamine (m-MTDATA) as a hole transport layer was impressive and the exciplex forming was confirmed. Finally, the electroluminescence with CIE (x,y) of (0.2076,0.3634) was resulted for the device consisted of low turn on voltage of 4.43 V, maximum brightness of 21362.55 cd m−2, maximum current and power efficiency of 27.03 cd A−1 and 19.65 lm.W−1 and maximum external quantum efficiency of 9.71%. [Display omitted] • New type of TADF dyes based on thioxanthenone derivative are synthesized. • The emission color changes under hammering. • The highest values for ionization potential and hole mobility were found to −5.49 eV and 3.56 × 10−4 cm2.V−1s−1 respectively. • Doped devices were fabricated using TFB as a host. • The maximum external quantum efficiency was achieved to 9.71%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two new TADF dyes with D-A-D' structure were designed and synthesized. • The emission color changes under well grinding and stimulation. • Electron and Hole mobilities were measured by SCLC and TOF methods, respectively. • The maximum external quantum efficiency of the doped OLEDs was achieved to 13.41%. In this study, we designed, engineered and investigated two new thermally activated delayed fluorescence (TADF) dyes obtained from D–A–D′ type, consisted of 2-(9H-carbazol-9-yl)-3-(3-methoxy-9H-carbazol-9-yl)-9H-xanthen and 2-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3-(3-methoxy -9H-carbazol-9-yl)-9H-xanthen. In these dyes, xanthen derivative and carbazole derivatives have played important roles as an acceptor and two unsymmetrical donor units. In addition, the photophysical properties of these dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay lifetime analysis in solution, initial dye, non-doped and doped solid state (neat–film) at different temperatures and under the vacuum-ambient. Substitution's strong effect of the donor units was impressive; where, the dyes' ionization potential values were achieved as 5.53 and 5.62 eV. The charge mobility measurements of dyes were carried out using two different methods of space charge–limited current (SCLC) and time of the flight (TOF). Appropriate extracted results proved dyes' promising application as an emitter layer in organic light emitting diodes (OLEDs), through the photophysical properties, aggregation induced emission enhancement (AIEE) phenomenon, and high intensity of emission spectrum spanning the large part of visible area and good thermal stability. The solution process and physical evaporation deposition (PVD) procedure were tandemly performed in order to coat the layers and fabricate non-doped and doped OLEDs. The low turned on voltage' values of OLEDs were recorded in the range of 4.08 to 5.31 V. Furthermore, the maximum values of brightness, current, power and external quantum efficiency were achieved as 72565 cd/m2, 37.32 cd/A, 20.99 lm/W and 13.41%, respectively. [ABSTRACT FROM AUTHOR]

Nanocomposite consisting of 5 mol% crystalline CuI-doped hydroxyapatite (HA) was prepared for the first time by facile chemical method and calcined at different temperatures such as 300 °C, 500 °C, 700 °C and 900 °C. In this study, HA played a role as the matrix and CuI was the reinforcement. The effect of calcination temperature on XRD pattern, TEM, SEM, BET, FTIR, luminescence intensity, photoluminescence quantum yield (PLQY), fluorescence lifetime, charge mobility measurements, electronic speckle pattern interferometry and mechanical properties were investigated. The modified Scherrer equation of the composites showed that the size of the particles increased with increasing calcination temperature from 66.64 to 87.20 nm. The photoluminescence intensity of CuI (5 mol%)/HA was quenched at room temperature, while the represented constant decay time for the calcined compound was increased at 700 °C. Furthermore, the CIE coordinates were shown 0.39333, 0.18493 for CuI (5 mol%)/HA calcined at 700 °C. The charge mobility values of the nanocomposites were extracted by space-charge limited current (SCLC) method and the range of effective mobility was from 3.645 × 10−4 to 6.697 × 10−4 cm2V−1s−1. Mechanical properties were fully discussed via ASTM-E9 standard and CuI (5 mol%)/HA calcined at 900 °C was in better range than other compounds, the σ yc and hardness values were reported 7.32 Mpa and 40.81 HV respectively. Speckle interferometry was used to demonstrate that there was no large imperfection in the surface of each sample. The components were very sensitive to the calcination temperatures. In other words, the combination of CuI (5 mol%)/HA showed that the replacement of Cu ions with Ca was helpful to improve the photophysical and mechanical properties. [Display omitted] • Facile synthesis of the CuI (5 mol%)–doped HA was performed. • The effect of calcination temperatures at 300 °C, 500 °C, 700 °C and 900 °C on the photophysical and mechanical properties was investigated. • Most of the properties was increased with increasing calcination temperature at 700 °C. • The effective hole mobility was found by SCLC method and the values recorded in the range from 3.645 × 10−4 to 6.697 × 10−4 cm2V−1s−1. [ABSTRACT FROM AUTHOR]

Taking into account X-ray diffraction, one of the well-known methods for calculating the stress-strain of crystals is Williamson-Hall (W–H). The W-H method has three models, namely (1) Uniform deformation model (UDM); (2) Uniform stress deformation model (USDM); and (3) Uniform deformation energy density model (UDEDM). The USDM and UDEDM models are directly related to the modulus of elasticity (E). Young's modulus is a key parameter in engineering design and materials development. Young's modulus is considered in USDM and UDEDM models, but in all previous studies, researchers used the average values of Young's modulus or they calculated Young's modulus only for a sharp peak of an XRD pattern or they extracted Young's modulus from the literature. Therefore, these values are not representative of all peaks derived from X-ray diffraction; as a result, these values are not estimated with high accuracy. Nevertheless, in the current study, the W-H method is used considering the all diffracted planes of the unit cell and super cells (2 × 2 × 2) of Hydroxyapatite (HA), and a new method with the high accuracy of the W-H method in the USDM model is presented to calculate stress (σ) and strain (ε). The accounting for the planar density of atoms is the novelty of this work. Furthermore, the ultrasonic pulse-echo test is performed for the validation of the novelty assumptions. [ABSTRACT FROM AUTHOR]

Recently, researchers have focused on the biocompatibility and mechanical properties of highly porous structures of biomaterials products. Porous composites are a new category of bioengineering that possess excellent functional and structural properties. In this study, the physical and mechanical properties of prepared doped silver (Ag)-hydroxyapatite (HA) by the mechanochemical and spark plasma sintering (SPS) methods were investigated. The influence of dopant on phase formation, structural properties, mechanical properties and morphological characteristics was investigated. Furthermore, in this case, as a new approach to produce a porous scaffold with an average size of >100 µm, the hair band was used as a mold. According to the Monshi–Scherrer method, the crystal size of scaffold was calculated 38 ± 2 nm and this value was in the good agreement with average value from transmission electron microscopy (TEM) analysis. In addition, the stress–strain compression test of scaffold was considered, and the maximum value of compressive strength was recorded ~15.71 MPa. Taking into account the XRD, TEM, Fourier-transform infrared (FTIR), scanning electron microscope (SEM) and energy dispersive X-Ray analysis (EDAX) analysis, the prepared scaffold was bioactive and the effects of doped Ag-HA and the use of polyvinyltrimethoxysilane (PVTMS) as an additive were desirable. The results showed that the effect of thermal treatment on composed of Ag and HA were impressive while no change in transformation was observed at 850 °C. In addition, PVTMS plays an important role as an additive for preventing the decomposition and creating open-microporous in the scaffold that these porosities can be helpful for increasing bioactivity. [ABSTRACT FROM AUTHOR]

In recent years, natural fiber reinforced polymer composites have gained much attention over synthetic fiber composites because of their many advantages such as low-cost, light in weight, non-toxic, non-abrasive, and bio-degradable properties. Many researchers have found interest in using epoxy resin for composite fabrication over other thermosetting and thermoplastic polymers due to its dimensional stability and mechanical properties. In this research work, the mechanical and moisture properties of Caryota and sisal fiber-reinforced epoxy resin hybrid composites were investigated. The main objective of these studies is to develop hybrid composites and exploit their importance over single fiber composites. The Caryota and sisal fiber reinforced epoxy resin composites were fabricated by using the hand lay-up technique. A total of five different samples (40C/0S, 25C/15S, 20C/20S, 15C/25S, 0C/40S) were developed based on the rule of hybridization. The samples were allowed for testing to evaluate their mechanical, moisture properties and the morphology was studied by using the scanning electron microscope analysis. It was observed that hybrid composites have shown improved mechanical properties over the single fiber (Individual fiber) composites. The moisture studies stated that all the composites were responded to the water absorption but single fiber composites absorbed more moisture than hybrid composites. [ABSTRACT FROM AUTHOR]

Calcium titanate-CaTiO3 (perovskite) has been used in various industrial applications due to its dopant/doping mechanisms. Manipulation of defective grain boundaries in the structure of perovskite is essential to maximize mechanical properties and stability; therefore, the structure of perovskite has attracted attention, because without fully understanding the perovskite structure and diffracted planes, dopant/doping mechanisms cannot be understood. In this study, the areas and locations of atoms and diffracted planes were designed and investigated. In this research, the relationship between Young's modulus and planar density of unit cell, super cells (2 × 2 × 2) and symmetry cells of nano CaTiO3 is investigated. Elastic constant, elastic compliance and Young's modulus value were recorded with the ultrasonic pulse-echo technique. The results were C11 = 330.89 GPa, C12 = 93.03 GPa, C44 = 94.91 GPa and E = 153.87 GPa respectively. Young's modulus values of CaTiO3 extracted by planar density were calculated 162.62 GPa, 151.71 GPa and 152.21 GPa for unit cell, super cells (2 × 2 × 2) and symmetry cells, respectively. Young's modulus value extracted by planar density of symmetry cells was in good agreement with Young's modulus value measured via ultrasonic pulse-echo. [ABSTRACT FROM AUTHOR]

This research paper is concentrated on the design of biologically compatible lead-free piezoelectric composites which may eventually replace traditional lead zirconium titanate (PZT) in micromechanical fluidics, the predominantly used ferroelectric material today. Thus, a lead-free barium–calcium zirconate titanate (BCZT) composite was synthesized, its crystalline structure and size, surface morphology, chemical, and piezoelectric properties were analyzed, together with the investigations done in variation of composite thin film thickness and its effect on the element properties. Four elements with different thicknesses of BCZT layers were fabricated and investigated in order to design a functional acoustophoresis micromechanical fluidic element, based on bulk acoustic generation for particle control technologies. Main methods used in this research were as follows: FTIR and XRD for evaluation of chemical and phase composition; SEM—for surface morphology; wettability measurements were used for surface free energy evaluation; a laser triangular sensing system—for evaluation of piezoelectric properties. XRD results allowed calculating the average crystallite size, which was 65.68 Å3 confirming the formation of BCZT nanoparticles. SEM micrographs results showed that BCZT thin films have some porosities on the surface with grain size ranging from 0.2 to 7.2 µm. Measurements of wettability showed that thin film surfaces are partially wetting and hydrophilic, with high degree of wettability and strong solid/liquid interactions for liquids. The critical surface tension was calculated in the range from 20.05 to 27.20 mN/m. Finally, investigations of piezoelectric properties showed significant results of lead-free piezoelectric composite, i.e., under 5 N force impulse thin films generated from 76 mV up to 782 mV voltages. Moreover, an experimental analysis showed that a designed lead-free BCZT element creates bulk acoustic waves and allows manipulating bio particles in this fluidic system. [ABSTRACT FROM AUTHOR]

Natural fibers have many advantages over synthetic fibers due to their lightness, low cost, biodegradability, and abundance in nature. The demand for natural fiber hybrid composites in various applications has increased recently, because of its promising mechanical properties. In this research work, the mechanical and wettability properties of reinforced natural fiber epoxy resin hybrid composites were investigated. The main aim of this research work is the fabrication of hybrid composites and exploit its importance over individual fiber composites. The composites were fabricated based on the rule of hybridization mixture (0.4 wf) of two fibers using sets of either hemp and flax or banana and pineapple, each set with 40 wt%, as well as four single fiber composites, 40 wt% each, as reinforcement and epoxy resin as matrix material. A total of two sets (hemp/flax and banana/pineapple) of hybrid composites were fabricated by using a hand layup technique. One set as 40H/0F, 25H/15F, 20H/20F, 15H/25F, 0H/40F, and the second one as 40B/0P, 25B/15P, 20B/20P, 15B/25P, 0B/40P weight fraction ratios. The fabricated composites were allowed for testing to examine its mechanical, wettability, and moisture properties. It has been observed that, in both cases, hybrid composites showed improved mechanical properties when compared to the individual fiber composites. The wettability test was carried out by using the contact angle measurement technique. All composites in both cases, hybrid or single showed contact angle less than 90°, which is associated with the composite hydrophilic surface properties. The moisture analysis stated that all the composites responded for moisture absorption up to 96 h and then remained constant in both cases. Hybrid composites absorbed less moisture than individual fiber composites. [ABSTRACT FROM AUTHOR]

Young's modulus (E) is one of the most important parameters in the mechanical properties of solid materials. Young's modulus is proportional to the stress and strain values. There are several experimental and theoretical methods for gaining Young's modulus values, such as stress–strain curves in compression and tensile tests, electromagnetic-acoustic resonance, ultrasonic pulse echo and density functional theory (DFT) in different basis sets. Apparently, preparing specimens for measuring Young's modulus through the experimental methods is not convenient and it is time-consuming. In addition, for calculating Young's modulus values by software, presumptions of data and structures are needed. Therefore, this new method for gaining the Young's modulus values of crystalline materials is presented. Herein, the new method for calculating Young's modulus of crystalline materials is extracted by X-ray diffraction. In this study, Young's modulus values were gained through the arbitrary planes such as random (hkl) in the research. In this study, calculation of Young's modulus through the relationship between elastic compliances, geometry of the crystal lattice and the planar density of each plane is obtained by X-ray diffraction. Sodium chloride (NaCl) with crystal lattices of FCC was selected as the example. The X-ray diffraction, elastic stiffness constant and elastic compliances values have been chosen by the X'Pert software, literature and experimental measurements, respectively. The elastic stiffness constant and Young's modulus of NaCl were measured by the ultrasonic technique and, finally, the results were in good agreement with the new method of this study. The aim of the modified Williamson–Hall (W–H) method in the uniform stress deformation model (USDM) utilized in this paper is to provide a new approach of using the W–H equation, so that a least squares technique can be applied to minimize the sources of errors. [ABSTRACT FROM AUTHOR]

We report on a comparison of methods based on XRD patterns for calculating crystal size. In this case, XRD peaks were extracted from hydroxyapatite obtained from cow, pig, and chicken bones. Hydroxyapatite was synthesized through the thermal treatment of natural bones at 950 °C. XRD patterns were selected by adjustment of X-Pert software for each method and for calculating the size of the crystals. Methods consisted of Scherrer (three models), Monshi–Scherrer, three models of Williamson–Hall (namely the Uniform Deformation Model (UDM), the Uniform Stress Deformation Model (USDM), and the Uniform Deformation Energy Density Model (UDEDM)), Halder–Wanger (H-W), and the Size Strain Plot Method (SSP). These methods have been used and compared together. The sizes of crystallites obtained by the XRD patterns in each method for hydroxyapatite from cow, pig, and chicken were 1371, 457, and 196 nm in the Scherrer method when considering all of the available peaks together (straight line model). A new model (straight line passing the origin) gave 60, 60, and 53 nm, which shows much improvement. The average model gave 56, 58, and 52 nm, for each of the three approaches, respectively, for cow, pig, and chicken. The Monshi–Scherrer method gave 60, 60, and 57 nm. Values of 56, 62, and 65 nm were given by the UDM method. The values calculated by the USDM method were 60, 62, and 62 nm. The values of 62, 62, and 65 nm were given by the UDEDM method for cow, pig, and chicken, respectively. Furthermore, the crystal size value was 4 nm for all samples in the H-W method. Values were also calculated as 43, 62, and 57 nm in the SSP method for cow, pig, and chicken tandemly. According to the comparison of values in each method, the Scherrer method (straight line model) for considering all peaks led to unreasonable values. Nevertheless, other values were in the acceptable range, similar to the reported values in the literature. Experimental analyses, such as specific surface area by gas adsorption (Brunauer–Emmett–Teller (BET)) and Transmission Electron Microscopy (TEM), were utilized. In the final comparison, parameters of accuracy, ease of calculations, having a check point for the researcher, and difference between the obtained values and experimental analysis by BET and TEM were considered. The Monshi–Scherrer method provided ease of calculation and a decrease in errors by applying least squares to the linear plot. There is a check point for this line that the slope must not be far from one. Then, the intercept gives the most accurate crystal size. In this study, the setup of values for BET (56, 52, and 49 nm) was also similar to the Monshi–Scherrer method and the use of it in research studies of nanotechnology is advised. [ABSTRACT FROM AUTHOR]

The present review article provides an overview of the properties of various natural and synthetic fibers for the fabrication of pure natural composites and the combination of both natural/synthetic fibers-based hybrid composites, bio-based resins, various fabrication techniques, chemical and mechanical properties of fibers, the effect of chemical treatment and the influence of nanoparticles on the composite materials. Natural fibers are becoming more popular and attractive to researchers, with satisfactory results, due to their availability, ease of fabrication, cost-effectiveness, biodegradable nature and being environmentally friendly. Hybrid composites made up of two different natural fibers under the same matrix material are more popular than a combination of natural and synthetic fibers. Recent studies relevant to natural fiber hybrid composites have stated that, due to their biodegradability and the strength of individual fibers causing an impact on mechanical properties, flame retardancy and moisture absorption, natural fibers need an additional treatment like chemical treatment for the fibers to overcome those drawbacks and to enhance their better properties. The result of chemical treatment on composite material properties such as thermal, mechanical and moisture properties was studied. Researchers found that the positive influence on overall strength by placing the filler materials (nanoparticles) in the composite materials. Hybrid composites are one of the fields in polymer science that are attracting consideration for various lightweight applications in a wide range of industries such as automobile, construction, shipping, aviation, sports equipment, electronics, hardware and biomedical sectors. [ABSTRACT FROM AUTHOR]