Chemical Data Collections最新文献

The primary focus of the study is to prepare and characterize water-soluble Boger fluids as they offer improved handling characteristics. The fluids have been prepared in the concentration range of 0.02–0.05 % (wt/vol.) Polyacrylamide (PAA) in a mixture of 80 % glycerol and 20 % distilled water by volume. Dynamic and steady shear data are represented in the temperature range of 15–35 °C. The shear mode data were fitted to power law model to calculate the flow consistency index (K) and flow behavior index (n). With increase in PAA concentration, the fluid character shifts from Boger to shear thinning viscoelastic fluid. Fluid relaxation time (λ) was calculated by fitting the oscillatory data to four mode Maxwell model. Empirical equations for the prediction of K, n, and λ are proposed by incorporating simultaneous effect of polymer concentration and temperature. Presented data could be of great use in unit operations such as fixed and fluidized beds dealing with Boger fluids.

This study assesses the impact of foaming agent type/content (hydrogen peroxide and Zn powder) and stabilizer content on the mechanical, thermal and microstructural of the elaborated geopolymer foams. Eighteen geopolymer foams were synthesized and their microstructure, density, porosity and compressive strength were analyzed before and after exposure to high temperatures (300 and 600 °C). To characterize the raw materials and the samples, several techniques were used, including X-ray fluorescence, X-ray diffraction, Magic-Angle Spinning Nuclear Magnetic Resonance Spectroscopy (²⁹Si and ²⁷Al MAS NMR), scanning electron microscopy (SEM), and porosity measurements. Thermogravimetric analysis was also performed to assess the thermal stability of the geopolymer foams with different foaming agent content and type. According to the results, the geopolymer foam with Zn powder as a foaming agent was more stable after exposure to the high temperature. The porosity increased after exposure to 300 °C, meanwhile decreasing after annealing at 600 °C.

High-voltage insulators were developed from CaCO₃ derived from waste snail shell to replace the low-impact energy ceramic insulators. The 15 wt% CaCO₃-snail shell/epoxy composite was produced using the solution stir-cast method. The UV radiation test, breakdown and flashover voltages, mechanical properties, tracking, and erosion depth of the developed composite were determined. A 116.7 and 43.82 % enhancement in the flashover voltage and leakage current was obtained at 1000 h of UV ageing. The developed insulator has longer thermal process breakdown strength and increased high-temperature insulation resistance. The properties attained in this work are within the acceptable range for high-tension insulator applications.It was established that waste snail shell could be used in the production of high-voltage insulators with high ultraviolet radiation resistance.

A new series of amide derivatives (10a–j) were designed and synthesized and their structures were confirmed by analytical data. Further, all these derivatives (10a–j) were examined for in vitro antitumor activity against four human cancer cell lines like MCF-7 (breast), A549 (lung), Col-205 (colon) and A2780 (ovarian) by using of the MTT assay. All the derivatives (10a–j) were exhibited remarkable anticancer effects on four cell lines as compared with etoposide used as a positive control. The IC₅₀ values range of tested compounds from 0.11 ± 0.051 µM to 7.42 ± 5.89 µM; whereas, positive control showed IC₅₀ values ranges from 0.17 ± 0.034 µM to 3.34 ± 0.152 µM, respectively. Among these derivatives, four compounds 10a, 10b, 10c & 10d demonstrated more potent activities than the positive control.

The existing work demonstrated the successful synthesis of WO₃ nanoparticles in one-pot system via self-assembly synthesis using triton-X as non-ionic polymer templating agent. The fast and efficient method was achieved by ultrasound irradiation. Characterization by using XRD, FTIR, XPS, UV-DRS, SEM, TEM and HRTEM demonstrated the formation of pure WO₃ having particle size of 10–25 nm. With the band gap energy of 2.25 eV, the prepared nanoparticles showed excellent photocatalytic performance towards tetracycline photooxidation with removal of 91.84 % during 60 of treatment.

Alzheimer's disease (AD) is a neurological illness. AD is often treated with rivastigmine (RV). The present study developed trilayer dissolving microneedle (TDMN) RV delivery system to overcome challenges in RV conventional forms. To enable the assessment of TDMN by ex vivo and in vivo methods, we developed a UV–Visible spectrophotometric method to quantify RV in four media using cobalt thiocyanate as a derivatization reagent. Guidelines set by the International Conference on Harmonization (ICH) were used to validate this approach. Results indicate a correlation coefficient of 0.9999 for all media, with the lower limit of quantification values for Phosphate Buffer Saline, rats’ plasma, skin, and brain matrices were 1.29, 0.67, 0.67, and 0.89 µg/mL, respectively. Significantly, the method is precise and accurate. Finally, to support this study's objective, TDMN formulation was developed, and direct application of the proposed method for quantifying RV in ex vivo and in vivo studies was conducted.

Contamination of water by toxic transition metal ions is increasing gradually. These metal ions cause various types of diseases. Therefore, some sew chemo-sensors 4,4′-((1E,1′E)-(propane-2,2-diylbis(4,1-phenylene))bis(diazene-2,1-diyl))bis(3,5-dihydroxybenzoic acid), [4,4′-((1E,1′E)-(oxybis(4,1-phenylene))bis(diazene-2,1-diyl))bis(3,5-dihydroxybenzoic acid), 4,4′-((1E,1′E)-(sulfonylbis(4,1-phenylene))bis(diazene-2,1-diyl))bis(3,5-dihydroxybenzoic acid), (E)-4-((4-(4-(2-(4-(4-carboxy-2,6-dihydroxyphenoxy)phenyl)propan-2-yl)phenoxy)phenyl)diazenyl)-3,5-dihydroxybenzoic acid] were synthesized and characterized by TLC, UV–Visible spectrophotometry, FTIR, and NMR techniques. The synthesized chemo-sensors exhibited the best performance in sensing the various types of transition metal ions by simply color variation. The detection of metal ions was also monitored by UV–Visible spectrophotometry through shifting in λ_max of chemo-sensors caused by interactions.

This research aimed to evaluate the chemical quality, antioxidant, and antimicrobial (antibacterial and antifungal) activity of essential oils (EOs) from three species of Eucalyptus: E. botryoides, E. cladocalyx, and E. grandis. The identification of the chemical profile of these essential oils revealed that 1,8-cineole, α-pinene, and β-(Z)-ocimene constitutes the significant compounds of these EOs. The antioxidant power tests of the essential oils of E. grandis and and E. cladocalyx shows a strong scavenging activity of the DPPH free radical with a percentage of 80.83 % and 80.46 % respectively at the concentration of 160 mg/mL, results confirmed by the FRAP test. As for the antimicrobial activity, the essential oils significantly inhibited the growth against all the strains studied. E. cladocalyx EOs were preferentially effective against fungi at the minimum inhibitory concentration of 1/2000 v/v, then E. grandis EOs were more effective against bacteria and fungi at the minimum inhibitory concentration of 1/1000 v/v. Finally, E. botryoides EO is less effective against the tested microbial strains.

A 1:1 cocrystal of 4-oxo-4-(pyridin-2-ylamino)butanoic acid (APS) and benzoic acid (BA), APS-BA (1:1), was prepared and characterized by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA), Infrared (FT-IR), powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SCXRD) studies. Crystal structure reveals that APS-BA (1:1) is formed by joint N-H…O and O-H…N hydrogen bonding between APS and BA molecule resulting in a hetero-dimeric R²₂(8) motif. A pair of C-H…O interactions and another pair of O-H…O hydrogen bonds between APS molecules ensures formation of a one-dimensional zig-zag hydrogen bonded tape of APS molecules, with the BA molecules occupying pendant position. Hirshfeld surface analysis including energy framework and lattice energy calculations were performed and compared with those of the components APS and BA. Comparison of the computed energetics of individual interactions and the lattice energies showed that cocrystal formation is thermodynamically favoured.