Frequency analysis of piezoelectric nanowires with surface effects

In this paper, the modified Timoshenko beam model is used to analyze the vibration of piezoelectric nanowires in the presence of surface effects. Analytical relations are given for the natural frequency of nanowires by accounting for the effects of surface elasticity, residual surface tension, and transverse shear deformation. Through an example, it is shown that the natural frequency depends on both the surface stresses and piezoelectricity. This study is expected to provide useful insights for the design of piezoelectric-nanowire-based nanodevices.     

Tactical supply chain planning models with inherent flexibility: definition and review

Supply chains (SCs) can be managed at many levels. The use of tactical SC planning models with multiple flexibility options can help manage the usual operations efficiently and effectively, whilst improve the SC resiliency in response to inherent environmental uncertainties. This paper defines tactical SC flexibility and identifies tactical flexibility measures and options for development of flexible SC planning models. A classification of the existing literature of SC planning is introduced that highlights the characteristics of published flexibility inclusive models. Additional classifications from the reviewed literature are presented based on the integration of flexibility options used, solution methods utilized, and real world applications presented. These classifications are helpful for identifying research gaps in the current literature and provide insights for future modeling and research efforts in the field.     

Chemical characterization and anti-hemolytic anemia potentials of tin nanoparticles synthesized by a green approach for bioremediation applications

The therapeutic properties of tin nanoparticles have been proved in recent years. One of their probable effects is anti-anemia. In this study, tin nanoparticles were synthesized and characterized in aqueous medium using Ziziphora clinopodioides Lam leaf aqueous extract as the reducing and stabilizing agent. We also assessed the antihemolytic anemia potential of tin nanoparticles (SnNPs) in an animal model of hemolytic anemia. Tin nanoparticles were characterized using many techniques including Fourier transform-infrared and UV-visible spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectrometry, and field emission-scanning electron microscopy (FE-SEM). FE-SEM images showed a uniform spherical morphology in size of 18.12 nm for the green synthesized nanoparticles. According to XRD analysis, SnNPs crystal size was17.94 nm. SnNPs had low cell viability dose-dependently against human umbilical vein endothelial cell line. in vivo design, induction of hemolytic anemia was done by phenylhydrazine in 40 mice. Tin nanoparticles significantly (p ≤ 0.01) reduced the weight and volume of liver and spleen and the concentration of pro-inflammatory cytokines, and increased the body weight, anti-inflammatory cytokines concentration, total platelet, WBC, neutrophil, lymphocyte, eosinophil, monocyte, and basophil counts, and red blood cell parameters compared to the untreated mice. For the biochemical parameters, SnNPs significantly (p ≤ 0.01) increased the concentrations of GPx, CAT, and SOD in serum, liver, and spleen and decreased the concentration of GR in serum, liver, and spleen, and also erythropoietin, ferritin, and ferrous in serum as compared to the anemic mice. The 2,2-diphenyl-1-picrylhydrazyl test showed similar antioxidant activities for SnNPs and butylated hydroxytoluene. The results demonstrate the excellent antihemolytic anemia, hematoprotective, cytotoxicity, and antioxidant potentials of SnNPs compared to other experimental groups.     

Deuterium nuclear magnetic resonance spectroscopy. 1—Larmor frequency ratio,referencing and chemical shift

Precise values for the ratio of the Larmor frequencies, w_1H/w_2H, were measured at constant field for various organic compounds. The values of the Larmor frequency ratio depend on carbon-hydrogen bond hybridization. The best ratio for the ghost referencing of ²H NMR spectra was then determined (6.514399862). This value enables an accurate ghost reference for any ²H NMR spectrum to be derived from the observed ¹H NMR frequency of the normal internal reference. Deuterium and proton chemical shifts measured from internal, partially deuteriated TMS under the same conditions are shown to be the same.     

A combined structure-based pharmacophore modeling and 3D-QSAR study on a series of N-heterocyclic scaffolds to screen novel antagonists as human DHFR inhibitors

Structural Chemistry - Dihydrofolate reductase (DHFR) is an essential enzyme that participates in folate metabolism and purine and thymidylate synthesis in cell proliferation. It converts...     

The endomorphism monoids and automorphism groups of Cayley graphs of semigroups

In this note, we introduce the notions of color-permutable automorphisms and color-permutable vertex-transitive Cayley graphs of semigroups. As a main result, for a finite monoid S and a generating set C of S, we explicitly determine the color-permutable automorphism group of \(\mathrm {Cay}(S,C)\) [Theorem 1.1]. Also for a monoid S and a generating set C of S, we explicitly determine the color-preserving automorphism group (endomorphism monoid) of \(\mathrm {Cay}(S,C)\) [Proposition 2.3 and Corollary 2.4]. Then we use these results to characterize when \(\mathrm {Cay}(S,C)\) is color-endomorphism vertex-transitive [Theorem 3.4].     

On‐line extraction and determination of two herbicides: Comparison between two modes of three‐phase hollow fiber microextraction

Two different modes of three‐phase hollow fiber liquid‐phase microextraction were studied for the extraction of two herbicides, bensulfuron‐methyl and linuron. In these two modes, the acceptor phases in the lumen of the hollow fiber were aqueous and organic solvents. The extraction and determination were performed using an automated hollow fiber microextraction instrument followed by high‐performance liquid chromatography. For both three‐phase hollow fiber liquid‐phase microextraction modes, the effect of the main parameters on the extraction efficiency were investigated and optimized by central composite design. Under optimal conditions, both modes showed good linearity and repeatability, but the three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents has a better extraction efficiency and figures of merit. The calibration curves for three‐phase hollow fiber liquid‐phase microextraction with an organic acceptor phase were linear in the range of 0.3–200 and 0.1–150 μg/L and the limits of detection were 0.1 and 0.06 μg/L for bensulfuron‐methyl and linuron, respectively. For the conventional three‐phase hollow fiber liquid‐phase microextraction, the calibration curves were linear in the range of 3.0–250 and 15–400 μg/L and LODs were 1.0 and 5.0 μg/L for bensulfuron‐methyl and linuron, respectively. The real sample analysis was carried out by three‐phase hollow fiber liquid phase microextraction based on two immiscible organic solvents because of its more favorable characteristics.     

New insights into the selective inhibition of the β-carbonic anhydrases of pathogenic bacteria Burkholderia pseudomallei and Francisella tularensis: a proteochemometrics study

Molecular Diversity - Nowadays, antibiotic resistance has turned into one of the most important worldwide health problems. Biological end point of critical enzymes induced by potent inhibitors is...     

Porous triazine polymer: A novel catalyst for the three-component reaction

A new porous triazine-based covalent organic polymer (Triazine-COP) was prepared through the Schiff-base condensation of 2,4,6-tris(4-formyl phenoxy)-1,3,5-triazine and 4,4′-oxydianiline, under sonication. The synthesized Triazine-COP with a high surface area was stable in water and other organic solvents. In the next step, Au (III) ions were immobilized on the nitrogen-rich Triazine-COP that on the reduction with NaBH₄ produced the heterogeneous catalyst of gold clusters in nanosize (Au-NCs@Triazine-COPs). It was applied as an efficient catalyst for the A³ coupling reaction of alkynes, aldehydes with and amines. Both electron-withdrawing/releasing groups produced the corresponding propargylamines with high yields. The high activity of the Au-NCs@Triazine-COPs in this reaction was because of the nanoporous structure of the support that enables the high dispersion and an unhindered open environment for the NCs. The catalyst was reused up to 7 times without significant loss in activity.