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111.
Synthesis of high temperature polyimide foams with pore sizes in the nanometer range was developed. Foams were prepared by casting graft copolymers comprising a thermally stable block as the matrix and a thermally labile material as the dispersed phase. The copolyimides as the matrix material were prepared via polycondensation reactions of pyromellitic dianhydride with three new diamines (4BAP, 3BAP, and BAN) through the poly(amic acid) precursors. Functionalized poly(propylene glycol) (PPGBr‐1000 and PPGBr‐2500) as the labile oligomer was prepared via reaction of poly(propylene glycol) monobutyl ether with 2‐bromoacetyl bromide. Graft copolymers were prepared by the reaction of the poly(amic acid)s with these thermally labile constituents. Upon thermal treatment the labile blocks were subsequently removed leaving pores with the size and shape of the original copolymer morphology. The polyimides and foamed polyimides were characterized by some conventional methods including FTIR, H‐NMR, DSC, TGA, SEM, TEM, and dielectric constant. The average pore size of the polyimide nanofoams was in the range of 5–20 nm. The structure–property relationships of the prepared nanofoams were investigated based on the diamine structures and also molecular weights of labile groups. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
112.
T. Dehghan-Zadeh A. R. Ashrafi N. Habibi 《Journal of Applied Mathematics and Computing》2014,46(1-2):285-303
In this paper, the first and second maximum values of the atom–bond connectivity index in the class of all n-vertex tetracyclic graphs are presented. 相似文献
113.
Recently introduced Zagreb coindices are a generalization of classical Zagreb indices of chemical graph theory. We explore here their basic mathematical properties and present explicit formulae for these new graph invariants under several graph operations. 相似文献
114.
Mohsen Zhaleh Akram Zangeneh Samaneh Goorani Niloofar Seydi Mohammad Mahdi Zangeneh Reza Tahvilian Elham Pirabbasi 《应用有机金属化学》2019,33(9)
The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. The aim of the experiment was chemical characterization and evaluation of cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing activities of gold nanoparticles using aqueous extract of Gundelia tournefortii L. leaves (AuNPs@GT). 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. DPPH free radical scavenging test was done to assess the antioxidant properties, which indicated similar antioxidant potentials for AuNPs@GT 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. AuNPs@GT indicated higher antibacterial and antifungal effects than all standard antibiotics (p ≤ 0.01). Also, AuNPs@GT inhibited the growth of all bacteria and fungi and removed them at 2‐4 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% HAuCl4 ointment, treatment with 0.2% G. tournefortii ointment, and treatment with 0.2% AuNPs@GT 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 AuNPs@GT 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, fibroblast, and fibrocytes/fibroblast rate compared to other groups. The synthesized AuNPs@GT had great cell viability dose‐dependently (Investigating the effect of the plant on HUVEC cell line) and revealed this method was nontoxic. The results showed that the leave aqueous extract of G. tournefortii is very good bioreductant in the synthesis of gold nanoparticles for treatment of bacterial, fungal, and skin diseases. 相似文献
115.
Here, a green method is described for the biosynthesis of Ag nanoparticles (Ag NPs) using aqueous extracts of the leaf of Salvia leriifolia as reducing and stabilizing agent. Various techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and X‐ray diffraction (XRD) were employed for the characterization of the structure and morphology of bio‐synthesized AgNPs. The results reveal that AgNPs synthesized with uniform spherical morphology and average diameters of 27 nm. The AgNPs as a green and efficient heterogeneous catalyst presented superior antibacterial activity. Direct electrochemistry studies of the synthesized AgNPs confirmed that nanoparticles retained their direct electrochemical activity. This is mainly attributed to the proper biosynthesis process, the large specific surface area and the good conductivity of the synthesized nanoparticles. Hence, the present synthesized AgNPs displayed good electrocatalytic activity to the reduction of nitrite ions. The proposed method is highly recommended as a novel platform for the development of electrochemical sensors which can further expand the applications of AgNPs. Antibacterial activity of the synthesized AgNPs was evaluated against nine microorganisms. AgNPs prevented the growth of all selected bacteria. The nanoparticles inhibited the growth of Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus coagulase, Acinetobacter baumannii, and Streptococcus pneumonia more than antibiotic of vancomycin, however, the ability of AgNPs against Echerishia coli and Serratia marcescens was less than the antibiotic. On the other hand AgNPs were active against Citrobacter frurdii, while the antibiotic was inactive. 相似文献
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117.
Samaneh Goorani Mohammad Kazem Koohi Hassan Morovvati Jalal Hassan Ahmad Ahmeda Mohammad Mahdi Zangeneh 《应用有机金属化学》2020,34(4):e5475
From time immemorial, people have tried to treat several diseases using natural compounds, including plants. Recently, researchers proposed that plants and herbal nanoparticles possess many remedial potentials. The results of this study confirmed the ability of an aqueous extract of Allium eriophyllum Boiss leaf grown under in vitro conditions for the biosynthesis of gold nanoparticles (AuNPs) and also revealed the anti-hemolytic anemia activity of AuNPs in an anemic rodent model. These nanoparticles were characterized using Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). TEM and FE-SEM images showed the biosynthesized nanoparticles as having a uniform spherical morphology and diameters in the range of 5–30 nm. In vivo design, the induction of hemolytic anemia, was done using phenylhydrazine in 40 mice. Then, the mice were randomly divided into five groups: HAuCl4, A. eriophyllum, AuNPs, untreated, and control. AuNPs significantly (p ≤ 0.01) decreased the concentration of glucocorticoid receptors in the serum, liver, and spleen, and also alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, total and conjugated bilirubin, cholesterol, triglyceride, low-density lipoprotein, urea, creatinine, ferrous, ferritin, and erythropoietin in the serum increased the concentrations of superoxide dismutase, catalase, and glutathione peroxidase (GPx) in the serum, liver, and spleen and also total protein, high-density lipoprotein, and albumin in serum in the control mice as compared to the anemic mice. Also, AuNPs significantly (p ≤ 0.01) increased the body weight; anti-inflammatory cytokine (IL4, IL5, IL10, IL13, and IFNα) concentration; and the total platelet, white blood cells, lymphocyte, neutrophil, monocyte, eosinophil, and basophil counts and red blood cell parameters but decreased the weight and volume of the liver and spleen and their subcompartments and decreased the concentration of pro-inflammatory cytokines (IL1, IL6, IL12, IL18, IFNY, and TNFα) compared to the untreated mice. In vitro design, using 2,2-diphenyl-1-picrylhydrazyl test, revealed similar antioxidant potentials for A. eriophyllum, AuNPs, and butylated hydroxytoluene. In addition, AuNPs were similar to A. eriophyllum and had a high cell viability dose dependently against the human umbilical vein endothelial cell line. In conclusion, the results of the chemical characterization confirm that the leaves of A. eriophyllum can be used to produce AuNPs with a remarkable amount of anti-hemolytic anemia property. 相似文献
118.
Two new one-dimensional metal–organic polymers (MOPs) {[Cu(L)(PPh2Py)·I2]·CH3Cl}n ( I ) and {[Cu(L)(PPh2Py)·Br2]·CH3Cl}n ( II ) (L = (1E,2E)-1,2-bis(pyridine-4-ylmethylene)hydrazine) (4-bpmh)) have been synthesized and elucidated by single crystal X-ray diffraction. The results of X-ray diffraction analysis unambiguously revealed that the two polymers are isostructural with the major intermolecular CH⋯π and π⋯π interactions. Microstructures of these polymers were also synthesized using a sonochemical method in different concentrations and reaction times. Field emission scanning electron microscopy, powder X-ray diffraction, thermogravimetric analysis and IR spectroscopy were applied to fully characterize these compounds. The photoluminescent properties of microrod MOPs were also evaluated to add to our understanding of their potential ability for nitro compound sensing. These experiments showed that MOPs I and II are good luminescence sensors for detection of nitro explosives in aqueous media. The probes maintained their high sensitivity and selectivity for 4-nitrophenol (4-NP). The energy transfer process accompanied by electrostatic interactions of 4-NP with these MOPs can be considered as an influential reason for the selectivity of 4-NP. The competitive study of the quenching process has a6lso shown superior operation with microparticles compared with bulky polymers. These results indicate that this method may be useful to synthesize luminescent materials possessing good sensing properties. 相似文献
119.
Narges Abdali Farhan Younas Samaneh Mafakheri Karunakar R. Pothula Ulrich Kleinekathöfer Andreas Tauch Roland Benz 《BMC biochemistry》2018,19(1):3
Background
Corynebacterium urealyticum, a pathogenic, multidrug resistant member of the mycolata, is known as causative agent of urinary tract infections although it is a bacterium of the skin flora. This pathogenic bacterium shares with the mycolata the property of having an unusual cell envelope composition and architecture, typical for the genus Corynebacterium. The cell wall of members of the mycolata contains channel-forming proteins for the uptake of solutes.Results
In this study, we provide novel information on the identification and characterization of a pore-forming protein in the cell wall of C. urealyticum DSM 7109. Detergent extracts of whole C. urealyticum cultures formed in lipid bilayer membranes slightly cation-selective pores with a single-channel conductance of 1.75 nS in 1 M KCl. Experiments with different salts and non-electrolytes suggested that the cell wall pore of C. urealyticum is wide and water-filled and has a diameter of about 1.8 nm. Molecular modelling and dynamics has been performed to obtain a model of the pore. For the search of the gene coding for the cell wall pore of C. urealyticum we looked in the known genome of C. urealyticum for a similar chromosomal localization of the porin gene to known porH and porA genes of other Corynebacterium strains. Three genes are located between the genes coding for GroEL2 and polyphosphate kinase (PKK2). Two of the genes (cur_1714 and cur_1715) were expressed in different constructs in C. glutamicum ΔporAΔporH and in porin-deficient BL21 DE3 Omp8 E. coli strains. The results suggested that the gene cur_1714 codes alone for the cell wall channel. The cell wall porin of C. urealyticum termed PorACur was purified to homogeneity using different biochemical methods and had an apparent molecular mass of about 4 kDa on tricine-containing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).Conclusions
Biophysical characterization of the purified protein (PorACur) suggested indeed that cur_1714 is the gene coding for the pore-forming protein in C. urealyticum because the protein formed in lipid bilayer experiments the same pores as the detergent extract of whole cells. The study is the first report of a cell wall channel in the pathogenic C. urealyticum.120.
Samaneh Miraee-Nedjad Paul F. G. Sims Jean-Marc Schwartz Andrew J. Doig 《BMC biochemistry》2018,19(1):9