Modified lattice Boltzmann solution for non-isothermal rarefied gas flow through microchannel utilizing BSR and second-order implicit schemes

Journal of Thermal Analysis and Calorimetry - Thermal microscale gas flow was simulated into a coplanar microchannel was simulated at a broad range of Knudsen numbers. Attempts were made to improve...     

H-point standard addition method for the selective simultaneous determination of nickel and copper using 1-(2-pyridylazo)-2-naphthol in Tween 80 micellar media.

The H-point standard addition method (HPSAM) has been applied for the simultaneous determination of nickel and copper in trace levels, using 1-(2-pyridylazo)-2-naphthol (PAN) as a chromogenic reagent in aqueous Tween 80 micellar media. Under the optimum condition, the simultaneous determinations of nickel and copper by HPSAM were performed. The absorbances at one pair of wavelengths, 548 and 579 nm, were monitored with the addition of standard solutions of copper. The method is able to accurately determine copper-to-nickel ratios of 15:1 to 1:10 (Wt/Wt). The effects of diverse ions on the determination of nickel and copper to investigate the selectivity of the method were also studied. The recommended procedure was successfully applied to some water and alloy samples.     

Comparative studies on a mesophilic and a thermophilic α-amylase

A comparative study was performed on thermal stability of mesophilic and thermophilic α-amylases, and the effects of various denaturing agents, organic solvents, and stabilizers were investigated. As expected, the thermophilic enzyme showed higher resistance toward denaturation in water as its natural medium, but such a difference could not be detected in nonaqueous environments. Furthermore, stability of these molecules was improved by including various stabilizing agents. Of the compounds tested, sorbitol provided the highest degree of protection, which was found to be owing to its effect on increasing T _m and its ability in totally preventing deamidation of amino acid residues in the protein molecules.     

A stereotypic,transplantable liver tissue-culture system

A method of coculturing adult rat hepatic parenchymal cells (PC) and stromal cells in a three-dimensional framework of nylon filtration screens or biodegradable polymer meshes was developed in our laboratory. Rat liver stroma, which includes vascular and bile duct endothelial cells, fat-storing cells, fibroblasts, and Kupffer cells, were isolated by gradient centrifugation afterin situ liver perfusion and expanded in monolayer culture prior to seeding onto nylon screens or bioresorbable polyglycolic acid (PGA) polymers oriented into a felt-like construct. A second inoculum of freshly isolated PC was applied after the stromal cells became established. Histological analyses revealed that PC proliferation occurred until all available space for expansion within the template was exhausted. These cells retained their rounded morphology, and after 4–5 wk 7–9 “layers” of PC filled the 140-μm deep template. Dioxin-inducible cytochrome P450 activity was detected for up to 58 d in culture, and albumin, fibrinogen, transferrin, and soluble fibronectin were detected in the medium by enzyme-linked immunosorbent assay (ELISA) for 48 d in vitro. Immunohistochemical analysis of sections through the cultures confirmed the presence of these proteins as well as cytokeratin at the cellular level; the extracellular matrix stained for both collagen type III and laminin. Long-term PC proliferation and function were enhanced by the presence of stromal cells as well as by a meshwork template whose geometry allows the interaction of PC with stroma and matrix on several different planes. To permit transplantation, co-cultures of hepatic PC and stromal cells were established on PGA felt constructs instead of nylon screens. After 24 d in vitro, these constructs were grafted into sites in the mesentery, omentum, and sub-cutaneous tissues of adult Long-Evans rats. The growth of hepatocytes after 30 din situ was evident by histological analysis; grafts of co-cultures regenerated a liver-like architecture consisting of sinusoids and putative biliary structures. In addition, PC at these extrahepatic graft sites were positive for albumin, transferrin, and fibrinogen synthesis by immunohistochemistry. Graft survival was enhanced when recipients were subjected to 40% hepatectomy. Hepatic PC:stromal cell cocultures may prove useful in the restoration of liver function either by direct transplantation using PGA or similar templates, or as extracorporeal devices, using nylon screens.     

Syntheses of substituted 1-methyl-2-(1,3,4-thiadiazol-2-yl)-4-nitropyrroles and 1-methyl-2-(1,3,4-oxadiazol-2-yl)-4-nitropyrroles

Starting from readily available ethyl-4-nitropyrrole-2-carboxylate ( 1 ), substituted 1-methyl-2-(1,3,4-thiadiazol-2-yl)-4-nitropyrroles and 1-methyl-2-(1,3,4-oxadiazol-2-yl)-4-nitropyrroles were prepared. The reaction of 1 with diazomethane gave ethyl 1-methyl-4-nitropyrrole-2-carboxylate ( 2 ). Reaction of compound 2 with hydrazine hydrate afforded the corresponding hydrazide 3 . The reaction of 3 with formic acid yielded 1-(1-methyl-4-nitropyrrole-2-carboxyl)-2-(formyl)hydrazine ( 7 ). Refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 6 in 40% yield. Reaction of compound 7 with phosphorus pentoxide afforded compound 9 . Reaction of compound 3 with 1,1′-carboxyldiimidazole in the presence of triethylamine yielded 2-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-oxadiazoline-4(H)-5-one ( 11 ). Refluxing compound 3 with cyanogen bromide in methanol gave compound 12 . Compound 13 could be obtained through the reaction of compound 3 with carbon disulfide in basic medium. Alkylation of compound 13 afforded the correspanding alkylthio derivative 14 . Reaction of 1-methyl-4-nitropyrrole-2-carboxylic acid ( 15 ) with thiosemicarbazide and phosphorus oxychloride gave 2-amino-5-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazole ( 16 ). Sandmeyer reaction of compound 16 yielded 2-chloro-5-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazole ( 17 ). Refluxing of the latter with thiourea afforded 2-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazoline-4(H)-5-thione ( 18 ). Alkylation of compound 18 gave the corresponding alkylthio derivative 19 . Oxidation of the latter with hydrogen peroxide in acetic acid yielded 2-(1-methyl-4-nitro-2-pyrrolyl)-5-methylsulfonyl-1,3,4-thiadiazole ( 20 ).     

Biomimetic pH/redox dual stimuli‐responsive zwitterionic polymer block poly(L‐histidine) micelles for intracellular delivery of doxorubicin into tumor cells

A series of pH/redox dual stimuli‐responsive poly(2‐methacryloyloxyethyl phosphorylcholine)₂₅‐block‐poly(l ‐histidine)_n (p[MPC])₂₅‐b‐p[His]_n, n = 20, 35, 50, and 75) copolymers consisting of a pH‐responsive p(His)_n block and a biocompatible phospholipid analog p(MPC) block connected by a redox‐responsive disulfide linker have been synthesized. The block copolymers are self‐assembled into uniform micelles (～100 nm) in which doxorubicin (Dox) is efficiently encapsulated. The in vitro release profile shows an enhanced release of Dox at low pH (5.0) in 10 mM glutathione (GSH). The in vitro cell viability assays performed using various cell lines show that the blank hybrid micelles have no acute or intrinsic toxicity. A pH‐dependent cytotoxicity is observed with the Dox‐loaded micelles, especially at pH 5.0. Moreover, confocal microscopy images and flow cytometry results show the pH‐dependent cellular uptake of Dox‐loaded micelles. Therefore, the Dox‐loaded micelles can be considered a good candidate for cancer therapy. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2061–2070     

Effect of Al2O3 nanoparticles on the steel-glass/epoxy composite joint bonded by a two-component structural acrylic adhesive

This paper reports a study on the effect of Al₂O₃ nanoparticles on the adhesion strength of steel-glass/epoxy composite joints bonded by a two-component structural acrylic adhesive. The addition of Al₂O₃ nanoparticles to the two-component acrylic adhesive led to a remarkable enhancement in the shear and tensile strength of the composite joints. The shear and tensile strength of the adhesive joints increased by addition of Al₂O₃ up to 1.5 wt%, which decreased by further addition of the nanofiller. Introduction of the nanoparticles caused a reduction in the peel strength of the joints. DSC analysis revealed that the glass transition temperature (Tg) of the adhesives rose by increasing the nanofiller content. The advancing water contact angle was decreased for adhesives containing nanoparticles. SEM micrographs indicated good dispersions of the Al₂O₃ nanoparticles within the acrylic matrix in the specimens with up to 1.5 wt% Al₂O₃ and revealed that addition of nanoparticles altered the fracture morphology from smooth to rough fracture surfaces.     

Preparation,characterization, and assessment of cytotoxicity,antioxidant, antibacterial,antifungal, and cutaneous wound healing properties of titanium nanoparticles using aqueous extract of Ziziphora clinopodioides Lam leaves

In recent decades, nanotechnology is growing rapidly owing to its widespread application in science and industry. The aim of the experiment was chemical characterization and evaluation of cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing activities of titanium nanoparticles using aqueous extract of Ziziphora clinopodioides Lam leaves (TiNPs@Ziziphora). These nanoparticles were characterized by fourier transformed infrared spectroscopy (FT‐IR), field emission scanning electron microscopy (FE‐SEM), energy dispersive X‐ray spectroscopy (EDS), and UV–visible spectroscopy. The synthesized TiNPs@Ziziphora had great cell viability dose‐dependently (Investigating the effect of the plant on human umbilical vein endothelial cells (HUVECs) cell line) and revealed this method was nontoxic. Then, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical scavenging test was done to assess the antioxidant properties, which indicated similar antioxidant potentials for TiNPs@Ziziphora and butylated hydroxytoluene. Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Fungicidal Concentration (MFC) were specified by macro‐broth dilution assay. The data were analyzed by SPSS 21 software (Duncan post‐hoc test). TiNPs@Ziziphora indicated higher antibacterial and antifungal effects than all standard antibiotics (p ≤ 0.01). Also, TiNPs@Ziziphora inhibited the growth of all bacteria at 2‐16 mg/ml concentrations and removed them at 2‐32 mg/ml concentrations (p ≤ 0.01). In case of antifungal properties of TiNPs@Ziziphora, they prevented the growth of all fungi at 2‐8 mg/ml concentrations and destroyed them at 2‐16 mg/ml concentrations (p ≤ 0.01). In vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: untreated control, treatment with Eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% TiO₂ ointment, treatment with 0.2% Z. clinopodioides ointment, and treatment with 0.2% TiNPs@Ziziphora ointment. These groups were treated for 10 days. For histopathological and biochemical analysis of the healing trend, a 3 × 3 cm section was prepared from all dermal thicknesses at day 10. Use of TiNPs@Ziziphora ointment in the treatment groups substantially reduced (p ≤ 0.01) the wound area, total cells, neutrophil, and lymphocyte and remarkably raised (p ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, and fibrocytes/fibroblast rate compared to other groups. In conclusion, the results revealed the useful non‐cytotoxic, antioxidant, antibacterial, antifungal, and cutaneous wound healing effects of TiNPs@Ziziphora.     

Biosynthesis of gold nanoparticles using Allium noeanum Reut. ex Regel leaves aqueous extract; characterization and analysis of their cytotoxicity,antioxidant, and antibacterial properties

Gold nanoparticles have unique and excellent medical and nonmedical properties and application compared with other metallic nanoparticles. Recently, they have been used for the prevention, control, and treatment of bacterial and fungal diseases. In the recent study, fresh and clean leaves of Allium noeanum Reut. ex Regel leaves have been used for the synthesis of gold nanoparticles. Also, we evaluated the cytotoxicity, antioxidant, and antibacterial properties of HAuCl₄, A. noeanum, and the synthesized nanoparticles (Au NPs). These nanoparticles were analyzed by FT‐IR, UV, XRD, EDS, FE‐SEM, and TEM tests. FTIR results offered antioxidant compounds in the plant were the sources of reducing power, reducing gold ions to Au NPs. In TEM images revealed an average diameter of 10‐30 nm. At the beginning of biological experiments, DPPH free radical scavenging test was carried out to examine the antioxidant property. Also, in the bacterial part of this study, the concentration of HAuCl₄, A. noeanum, and AuNPs with minimum dilution and no turbidity was considered MIC. To determine MBC, 60 μL of MIC and three preceding chambers were cultured on Muller Hinton Agar. The minimum concentration with no bacterial growth was considered MBC. Au NPs revealed excellent antioxidant potential against DPPH, non‐toxicity property against human umbilical vein endothelial cells, and antibacterial activities against Streptococcus pneumonia, Bacillus subtilis, Staphylococcus aureus, Staphylococcus saprophyticus, Salmonella typhimurium, Pseudomonas aeruginosa, Shigella flexneri, and Escherichia coli O157:H7. These findings show that the inclusion of A. noeanum extract improves the solubility of Au NPs, which led to a notable enhancement in the antioxidant and antibacterial effects.     

Using a Natural Surfactant for Synthesize of NiO and CuO Nanostructures via Simple and Fast Microwave Approach

NiO and CuO nanostructures were synthesized successfully via simple and fast microwave approach. Olive oil was chose as surfactant for stabilizing nanostructures. Different parameters such as microwave time and power and olive oil concentration were investigated on product size and morphology. The products were characterized with X-ray diffraction pattern, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry analysis.