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A series of pyrazole ligands named as 1,4-bis(3,5-dimethylpyrazol-1-yl)butane (bbd), 1,3-bis(3,5-dimethylpyrazol-1-yl)propane (bdpp), and 1,3-bis(3,5-dimethylpyrazol-1-yl)propane-2-ol (bdpo) along ...

CoFe2O4@SiO2/HKUST-1 as a novel three-metallic magnetic metal-organic framework (MMOF) has been favorably synthesized via a simple self-assembly method. For this purpose, CoFe2O4@SiO2 was functionalized by Glutaric anhydride and 3-(triethoxysilyl)propylamine and then HKUST-1 was synthesized on the surface of CoFe2O4@SiO2. Powder X-ray diffractometry (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM), and simulated thermal analyzer (STA) were utilized to characterize the as-prepared samples. The methylene blue (MB) removal efficiency of CoFe2O4@SiO2/HKUST-1 has been set by examining factors such as the effect of pH, concentration of dye, amount of adsorbent, and components of a compound. Up to 100 percent dye removal in short reaction times and water media was reached in alkaline pH, by increasing the dose of adsorbent and in the presence of CoFe2O4@SiO2 and CoFe2O4@SiO2/HKUST-1 compounds. Freundlich adsorption isotherm that uses to describe the ongoing adsorption was found to be best fitted for the adsorption process.Based on pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic equations, the pseudo-second-order kinetic model with rate constant (k2) 4 x10-3 g/mg.min is best fitted for adsorption methylene blue, indicating that removal of dye takes place dominantly through the chemisorption process.

In this study, a simple method was developed to prepare gentamaicin (GEN)—loaded nanoscale zeolitic imidazolate framework-8 (GEN@NZIF-8) nanoparticles (NPs) at room temperature and GEN@NZIF-8 NPs were characterized by FT-IR spectroscopy, powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, BET nitrogen adsorption–desorption, and UV–Vis spectroscopy. The PXRD patterns showed that large drug molecules can be encapsulated in ZIF-8 frameworks. Thermogravimetric analysis confirms that the GEN@NZIF-8 NPs have higher thermal stability than ZIF-8 NPs. FT-IR spectroscopy exhibted the presence of functional groups of GEN and NZIF-8 frameworks in GEN@NZIF-8 NPs. Results showed that GEN@NZIF-8 NPs exhibited high drug capacity (19%) and high drug loading capacity of gentamicin anions through ion exchange and good chemical stability. The researchers attempted to demonstrate that large drug molecules at pH 5.0 and 7.4 could be loaded in NZIF-8 NPs. Additionally, drug release in acidic condition was faster than in physiological condition. The biological activities of GEN, NZIF-8 and GEN@NZIF-8 NPs against Gram-positive and Gram-negative bacteria showed that the GEN@NZIF-8 NPs had good antimicrobial activity. This work highlights the potential of using NZIF-8 as a valuable candidate to develop highly efficient drug delivery vehicles in the treatment of infectious diseases using pH-responsive release.

Al2O3/PVP nano-hybrid composite samples are synthesized using Sol–Gel method at 80 °C. Weight percent of poly 4-vinyl phenol (PVP) and aluminum oxide is 0.0, 0.28, 0.56, and 0.84. To study the nano-structural and electrical characteristics, X-ray diffraction, Fourier transfer infrared radiation, scanning electron microscopy, and atomic force microscopy are used. Dielectric constant of the samples is calculated using GPS 132A technique. The results show that the highest amounts of dielectric constant at the frequency of 120 and 1 kHz are related to Al2O3/0.28 wt% PVP (AP 0.28 wt%). PVP (k = 35) and Al2O3/0.56 wt% PVP (AP 0.56 wt%). PVP (k = 26) nano-composite samples, respectively. Therefore, at the frequency of 120 kHz, AP 0.28 wt% PVP nano-composite sample, due to having higher equivalent oxide thickness, less roughness, ohmic properties, smaller size of nano-crystallites (Scherrer diameter of 45 nm), higher dielectric constant, and as a result less leakage current, is recommended as the gate dielectric for the future of organic field effect transistors (OFET).

A spatially resolved crystal plasticity finite element model in conjunction with computational homogenization is proposed to simulate the micromechanisms of cyclic plastic deformation of an extruded ZK60 magnesium alloy. Dislocation slipping, twinning and detwinning are included through an integrated framework. The ability of the proposed model to reproduce experimental macroscopic responses has been evaluated through the numerical solution of a real representative volume element (RVE) of microstructure under strain-controlled cyclic loading. The proposed model can capture the main macroscopic cyclic plastic characteristics of the ZK60 extruded Mg alloy including asymmetry in stress–strain curve, mechanical anisotropy, strain amplitude dependency of response, mean stress evolution and Bauschinger effect. Simulations were carried out up to 1 % macroscopic strain. In agreement with experimental texture, both basal as well as off-basal grains, whose c-axes deviate from being normal to extrusion direction (ED), are included in the RVE. To assess the micromechanisms of cyclic plastic deformation three distinct grain ensembles termed as microtextures have been implanted in the bulk texture. The mixed grain cluster consists of both basal and off-basal grains. Off-basal microtexture is comprised of off-basal grains. Twinned microtexture is formed when a few contiguous grains are in a favorable position for twinning. The simulation results show that under certain conditions, off-basal and twinned microtextures can act as a channel for long-range flow softening and strain localization which evolves with loading cycles. Additionally, severe incompatible plastic deformation stemming from the presence of micro-textures induces short or long-range evolving intergranular stress concentration.

HoxCd1−xS (0 ≤ x ≤ 0.12) nanoparticles with different Holmium contents were successfully synthesized via hydrothermal method. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance spectroscopy techniques. Photocatalytic efficiency of pure and HoxCd1−xS samples was evaluated by monitoring the decolorization of RRed 43 in aqueous solution under visible light irradiation. 8 % Ho-doped CdS nanoparticles indicated the highest decolorization among the different amounts of dopant agent used. The effect of operational parameters including doping level, catalyst dosage, initial dye concentration and radical scavengers on the photocatalytic activity were evaluated. The Langmuir–Hinshelwood (L–H) model was evaluated for the photocatalytic process.

In this study, the MoS 4 Cu 4 (Pz Me3 ) 6 Cl 2 is synthesized and its optical nonlinear responses are investigated in the regime of low laser power using a continuous wave He-Ne (632.8 nm, 35 mW). The single beam z-scan method is used to measurements. The values of the nonlinear refraction and nonlinear absorption coefficient are measured to be 4.09 × 10 −9 m 2 W −1 and 0.03 mW −1 respectively. The third order nonlinear susceptibility is found to be in the order of 10 −6 esu. The experimental observations of the self focusing effect and the far-filed diffraction ring patterns are reported.

We prepared pure and samarium-doped ZnS (SmxZn1−xS1+0.5x) nanoparticles via hydrothermal process at 160 °C for 24 h. XRD analysis shows that the particles were well crystallized and corresponds to a cubic sphalerite phase. SEM and TEM images indicate that the sizes of the particles were in the range of 20–60 nm. The photocatalytic activity of Sm-doped ZnS nanoparticles was evaluated by monitoring the decolorization of Reactive Red 43 in aqueous solution under visible light irradiation. The color removal efficiency of Sm0.04Zn0.96S and pure ZnS was 95.1% and 28.7% after 120 min of treatment, respectively. Among the different amounts of dopant agent used, 4% Sm-doped ZnS nanoparticles indicated the highest decolorization. We found that the presence of inorganic ions such as Cl−, CO32− and other radical scavengers such as buthanol and isopropyl alcohol reduced the decolorization efficiency.

Pr-doped ZnS nanoparticles with variable praseodymium contents were successfully synthesized via a hydrothermal process. The products were characterized by XRD, SEM, TEM, XPS, TGA and UV–vis techniques. The photocatalytic performance of the as-synthesized nanoparticles was investigated for the decolorization of Reactive Blue 19 solution under visible light irradiation. The highest decolorization was achieved with 3% Pr-doped ZnS nanoparticles. The order of inhibitory effect of radical scavengers was butanol > Cl− > CO32− > isopropyl alcohol. The Langmuir–Hinshelwood (L-H) adsorption and rate coefficients for the photocatalytic process were successfully established.

Nano-structures of a new discrete coordination compound of divalent cobalt with the pyrazol (pzH) containing the terminal isothiocyanate anions, [Co(pzH)2(NCS)2] (1), with discrete molecular architecture in solid state was synthesized by a sonochemical method. The new nanostructure was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, IR, and elemental analysis. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The discrete molecules interact with each other through labile interactions creating a 3D supramolecular framework. The CoO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant.

Utilizing one of the mesh free methods, the present paper concerns static analysis of thin plates with various geometric shapes based on the mindlin classical plate theories. In this numerical method, the domain of issue is solely expressed through a set of nods and no gridding or element is required. To express the domain of issues with various geometric shapes, first a set of nodes are defined in a standard rectangular domain , then via a three-order map with, these nodes are transferred to the main domain of the original issue; therefore plates of various geometric shapes can be analyzed. Among meshfree numerical methods, Element Free Galerkin method (EFG) is utilized here. The method is one of the weak form integral methods that uses MLS shape functions for approximation. Regarding the absence of Delta feature in MLS functions, boundary conditions cannot be imposed directly; hence the Lagrangian method is utilized to impose boundary conditions. At the end, our outputs are compared with those of analytic and finite element methods for plates, in order to validate the exactness of our solution method, and then after reliability is established, a few new examples will be solved.

The water-oxidizing complex or oxygen-evolving complex in plants, algae and cyanobacteria is an Mn4CaO5 cluster catalysing light-induced water oxidation. Herein we report that nano-sized Mn oxide/carbon aerogel is an active and low-density catalyst toward water oxidation. The composite was synthesized by a simple, low-cost procedure with different ratio of carbon aerogel to Mn oxide and characterized by scanning electron microscopy, energy-dispersive spectroscopy, high resolution transmission electron microscopy, X-ray diffraction, electronic spectroscopy, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy. Then, the water-oxidizing activity of this composite was considered in the presence of cerium(IV) ammonium nitrate. The composites with a high ratio of Mn oxide to carbon aerogel are good Mn-based catalysts with turnover frequencies of ∼0.33 (mmol O2/(mol Mn·s)). In addition to the water-oxidizing activities of these composites under different conditions, their self-healing reaction in the presence of cerium(IV) ammonium nitrate was studied. We also compare the composite with graphene quantum dots/Mn oxide, which is not stable under these conditions. Using hydrogen to store sustainable energies is a promising strategy in the near future and our results show that nano-sized Mn oxide/carbon aerogel is a promising catalyst for water-splitting systems toward hydrogen evolution.

Two important phenomena of “quantum tunneling” and “self-energy” are particularly important in nanocomposites, because tunneling of electrons or holes through the ultra-thin dielectric barrier and excluding the screening of these carriers can cause the loss of control over current passing through these nanocomposites. Here, due to great density of carriers that are seen as condensed quantum dots, the system is regarded as a many-body system with quantum dots interaction, and the self-energy equation is obtained using Green’s function equations, screening, polarization, and dielectric constant related to aluminum oxide (Al2O3) and poly vinyl phenol nanocomposites. Also, according to the current density verse applied voltage (I–V) and non-uniform structures of the samples, the equation for the current density of the quantum tunneling is achieved.

Wrought magnesium alloys exhibit strong basal texture after extrusion or rolling process. In this study, a numerically improved crystal plasticity finite element model in conjunction with computational homogenization has been used to investigate the micromechanism of strain localization in AZ31 Mg alloy under uniaxial tension along rolling direction (RD), uniaxial compressin along normal direction (ND) and biaxial tension in RD-TD plane. To this aim, the effect of texture and especially off-basal grains distribution on strain localization is elaborated in detail. Three realistic representative volume elements (RVE) of microstructure with 34, 60 and 58 grains and ≈ 578 , ≈ 546 and ≈ 1103 elements per grain have been synthetically constructed and analyzed to examine the effect of basal and off-basal grains distribution on the deformation patterns. Strongest strain localization was found in RVE. 1 where off-basal grains were arranged in a banded form. RVE. 2 with differing spatial position of off-basal grains showed weaker, yet discernible localized band. RVE. 3 with a nearly random distribution of off-basal grains depicted no clear side-by-side localized band. It was found that basal slip is the main contributor of compound strain localization regions. Moreover, high stresses inside the localized band can enforce well-oriented grains for non-basal slip located between off-basal grains to deform cooperatively. Upon the formation of localized bands, the remaining part of the RD-TD faces experienced insignificant deformation and clear deformation partitioning occurred. Regarding RD-ND faces, two distinct microscale localized zones have been observed. Basal and prismatic slip was the former of localized zones on the RD-ND faces.

This work deals with the effects of waviness and aspect ratio on the buckling behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates subjected to in-plane loads using reproducing kernel particle method (RKPM) based on modified first-order shear deformation theory (FSDT). Wavy single-walled carbon nanotubes (CNTs) are embedded in a polymer matrix and distributed in four types of distributions. The material properties of an FG-CNTRC plate are assumed to be graded along the thickness direction of the plate and estimated through a micromechanical model based on the extended rule of mixture. The modified shear correction factors evaluated involving the nonuniform shear stress distribution through the thickness of the FG-CNTRC plate. For the imposition of the essential boundary conditions the full transformation approach is utilized. The validity and accuracy of the RKPM method is established by a comparison with the obtained results of available literature data. Moreover, the effects of distribution, volume fraction, waviness, and aspect ratio of CNTs are investigated on the buckling behavior of FG-CNTRC plates for various boundary conditions, plate width-to-thickness and aspect ratios. Detailed parametric studies demonstrate that the waviness and aspect ratio of CNTs have noticeable effects on buckling behavior of carbon nanotube-reinforced composite (CNTRC) plates. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Water splitting is considered as a method to storage of renewable energies to hydrogen. The water-oxidation reaction in water splitting is an efficiency-limiting process for water splitting, and thus, there has been notable progress to find highly efficient water-oxidizing catalysts made from cost-effective and earth-abundant elements. In addition to efficiency, the stability of the water-oxidizing compounds is very important. Herein we focus on self-healing in manganese-based water-oxidizing catalysts in artificial photosynthetic systems.

Nano-structures of a new supramolecular coordination compound of divalent nickel with the pyrazol (pzH) containing the terminal azide anions, [Ni(pzH)2(N3)2] (1), with discrete molecular architecture (DMA) in solid state was synthesized via sonochemical method. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, IR, and elemental analysis. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal X-ray data shows that the coordination number of Ni (II) ions is six, (NiN6), with four N-donor atoms from neutral "pzH" ligands and two N-donors from two terminal azide anions. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are consistent with the crystal structure. The NiO nanoparticles were obtained by thermolysis of 1 at 180°C with oleic acid as a surfactant.

Ultrasound was used to synthesize nano-structures of [Ni(bpzB)2]2(1), a new two-nuclear discrete-coordination compound of divalent nickel with bis-pyrazolyl borate(bpzB). The nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, infrared, and elemental analysis. The single-crystal X-ray data show that the coordination number of Ni(II) ions is four (Ni1N4 and Ni2N4) with square planar geometry. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The discrete molecules interact with each other through labile interactions, creating a 3D supramolecular framework.

In this paper, the buckling behavior and critical axial pressure of double-walled carbon nanotubes (DWCNTs) with surrounding elastic medium are investigated. A double-shell (circular cylindrical shell) model is presented and the effects of surrounding elastic medium on the outer tube and the van der Waals forces between two adjacent tubes are taken into account. The analysis and the numerical solution method are based on the classical theory of plates and shells and the Galerkin method. Equations are derived for the critical axial forces and pressures of DWCNTs; the critical axial forces and pressures are calculated for different axial half sine wavenumbers and circumferential sine wavenumbers and compared with those for single-walled carbon nanotubes (SWCNTs). Results indicate that the critical axial force of a DWCNT is higher than that of an SWCNT, but the critical axial pressure of a DWCNT is lower than the critical axial pressure of a SWCNT. Although the critical axial force of a DWCNT decreases as the axial half sine wavenumbers increase, it rises as the circumferential sine wavenumbers increase.