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991.
Alzahrani Jamila S. Alrowaili Z. A. Saleh H. H. Al-Baradi Ateyyah M. Alothman Miysoon A. Al-Buriahi M. S. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4300-4312
Journal of Inorganic and Organometallic Polymers and Materials - This research article focuses on the significant role of Tb2O3 content on the optical properties and radiation shielding performance... 相似文献
992.
Autocorrelation method (Single time series) is new method for analysis of plasma mode in Tokamaks. In this article autocorrelation method has been compared with SVD method. Energy of the modes which obtained by SVD analysis showed that the autocorrelation method is a cited method for mode detection. 相似文献
993.
Microvascular architectures with specific channel fractions and channel orientations have been reported for thermal insulation and functional fluid delivery applications. However, the dependence on channel network structure of the inevitable loss in strength and stiffness has not been adequately characterized, especially at moderate-to-high channel fractions and in anisotropic systems. In this work, the loss in mechanical performance of a thermosetting epoxy is explored in tensile, flexure, and compression modes over a wide range of microchannel fractions and different microchannel orientations. Whereas microchannel fractions of 0.7 can result in reductions of more than 90% in mechanical properties relative to the nonchanneled material, there is a strong influence in microchannel orientation over the full range of microchannel fractions studied. The data are compared to a power-law model, which shows a good agreement with the experimental measurements, provided that the power-law exponent is adjusted to depend on the direction of microchannel alignment. These results demonstrate the opportunity to engineer the mechanical properties of multifunctional microchannel systems for a range of existing and emerging applications, by controlling both the microchannel volume fraction and the microchannel orientation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47945. 相似文献
994.
The bark of trees is an abundant material for chemical by-products. The combination effects of different concentrations of Acer saccharum var. saccharum inner (IB) and outer (OB) bark acetone extracts with citric acid (CA) applied to Leucaena leucocephala wood were evaluated against the growth of three common molds (Trichoderma viride, Fusarium subglutinans, and Aspergillus niger). IB, OB, and CA solutions were prepared at 0.25% and 0.5% and their combinations were formulated in equal amounts. Acetone extracts of IB and OB were analyzed for their chemicals composition and phenolic compounds using GC/MS and PHLC, respectively. The IB acetone extract contained 4-hydroxy-4-methyl-2-pentanone (31.67%), palmitic acid (15.52%), and linoleic acid (11.14%), while the OB acetone extract contained 1,2-benzenedicarboxylic acid, bis(2-ethylhexyl) ester (9.34%), (Z,E)-9,12-tetradecadien-1-ol (8.86%), and cis-tetrahydro-6-methoxy-2H-pyran-3-ol (5.72%). The HPLC analysis indicated the presence of 14 phenolic compounds in IB extract with major constituents caffeine (362.88?µg/g extract), and p-hydroxy benzoic acid (358.06?µg/g extract), while OB contained 12 compounds with major constituents p-hydroxy benzoic acid (8950.5?µg/g extract), gallic acid (5261?µg/g extract) and salicylic acid (572.38?µg/g extract). High total phenolic content in OB (292.67?mg GAE/g) was associated with high antioxidant activity with an IC50 values of 1.77 and 4.14?μg/mL, as measured by DPPH and β-Carotene-linoleic acid, respectively. The combination treatment of IB0.25%+ OB0.25%+CA0.25% produced the highest antifungal effects against growth of T. viride with an inhibition percentage (IP) of 10.37%, IB0.5%+CA0.5% (IP 16.66%) with F. subglutinans, while CA0.5% and OB0.25%, showed IP of 27.77% and 23.70% with A. niger, respectively. The combination effects of IB, OB and CA could be used as biocide agents for preventing mold growth on wood. 相似文献
995.
A series of novel thieno[2,3-b]pyridines were prepared from the reaction of the appropriate bromoacetylbenzofurans or bromoacetylbenzothiazole with the corresponding pyridinethione derivatives in ethanolic sodium ethoxide at reflux. Moreover, new bis(thieno[2,3-b]pyridine) derivatives have also been synthesized by the reaction of the appropriate bis-bromoacetyl derivatives with the corresponding pyridinethiones in the presence of sodium ethoxide. Attempts to synthesize the target bis(thieno[2,3-b]pyridine) derivatives by bis-alkylation of the corresponding (thieno[2,3-b]pyridin-2-yl)(hydroxyphenyl)methanone with the appropriate dihaloalkanes using a mild base were unsuccessful. 相似文献
996.
Mohamed A. Salem 《Reactive and Functional Polymers》2010,70(10):707-714
Three polyaniline salts (PANI–H2SO4, PANI–H3PO4, and PANI–HNO3) have been synthesized by chemical oxidative polymerization of aniline. They have been tested as adsorbents for the removal of the textile dye direct blue 78 (DB78) from aqueous solution. The interaction followed pseudo-second-order kinetics whether the rate of interaction was measured from the depletion of dye concentration in solution or the increase in the amount of dye adsorbed on the PANI surface. The removal rate was a function of the activity of the polymer as well as the reaction parameters of the polymer/dye system. The activity of the PANI depended on the polymerization conditions. These conditions involve the concentration of aniline, ammonium peroxydisulfate as oxidant, and sodium dodecylsulfate (SDS), the type of dopant acid (H2SO4, H3PO4, HNO3), and the polymerization time. Higher removal rate was observed at oxidant/aniline mole ratio equals 1. The rate of removal was in the order PANI–H3PO4 > PANI–H2SO4 > PANI–HNO3. The rate decreased with increasing the concentration of DB78 and pH. It increased with increasing the load of PANI. Pseudo-second-order kinetics, external surface adsorption, and intraparticle diffusion models were concurrently operating in the removal of DB78 with PANI. 相似文献
997.
Hend Ben Hadj Salah Hachmi Ben Daly Johanne Denault Florence Perrin 《Polymer Engineering and Science》2016,56(4):469-478
The aim of this work is to experimentally characterize the UV‐degradation process at both the surface and at different layers across the thickness of injection‐molded polypropylene (PP) matrix containing different amounts of nanosized montmorillonite (MMT) clay particles. These nanocomposite materials have been exposed to UV irradiations (λ = 320 nm) at different preset temperatures (25, 45, and 65°C) in the presence of oxygen and during different exposure times. The extent of such process at these layers was determined using both the FTIR spectroscopy and the wide‐angle X‐ray diffraction analyses. The micromechanical properties across the thickness have been characterized using the nanoindentation technique. The obtained results have indicated that the UV‐degradation process for the nanocomposite materials is much more intense than the one observed for the neat PP. Moreover, it has been noted that such degradation process is not uniform across the thickness of the exposed materials. Results obtained from the X‐ray analysis have shown an increase of the crystallinity of the polymer molecules at only the external surface of the exposed materials. This was confirmed using the nanoindentation test as an increase of the Young's modulus at this layer was noted. POLYM. ENG. SCI., 56:469–478, 2016. © 2016 Society of Plastics Engineers 相似文献
998.
999.
Kaolin porous support ceramic was prepared from kaolin. The characterization of the porous properties and structure of the support synthesis was carried out by scanning electron microscopy (SEM), absorption rate, shrinkage rate and Hg-porosimetry methods. The pore size distribution showed a unimodal pore size distribution with an average pore size of about 0.9 µm. The reliability of support was measured by filtration tests and removal of heavy metals.Filtration studies using porous tubular supports were performed for solutions containing methylene blue and Evans blue. The study of the liquid filtration and flow through these supports showed that the methylene blue rejection rate was 99% while the Evans blue rate reached 90% for a 90 minute filtration time under a pressure of 2 bar. We beforehand tested the flow rate for each support with distilled water and the results show that the support of kaolin gave a flux for distilled water of 31.0 L/h at the pressure of 2 bar. At a pressure of 3.5 bar an increase in the distilled water flux through the support was observed.The rejection rate of cadmium ions was more significant. A rejection rate of 99.99% using a 10− 4 mol/L solution of this heavy metal for two-hour treatment time was obtained. 相似文献
1000.
In recent years, fiber-reinforced polymers (FRPs) materials have shown great potential as materials for repair and reinforced concrete structures such as beams or columns by externally bonding FRP sheet(s) onto the surface of substrate concrete structures. However, the performance of FRP systems exposed to fire is a serious concern due to the combustibility of FRPs. This study introduces the results of an experimental investigation on the behavior of the circular columns of concrete under a load of axial compression, confined by an envelope of composite materials (carbon fiber and glass fiber) and protected by a layer of mortar cement or plaster coating, after they have been subjected at various temperature (23, 120, and 350 °C). The specific objectives of this study are verifying the applicability and the effectiveness of the proposed technique to improve the behavior of concrete in fire resistance and evaluate the effect of composite materials and the layer coating type used. The results indicated that protecting heat circular confined columns, with a layer of mortar cement or plaster has a significant effect on the axial strength and the ductility. It was shown that the ultimate load and axial strain of heated columns can be restored up to the original level or greater than those of unheated columns. However, the effect of a layer of plaster is more significant than a layer of mortar cement. So this coating system would enhance fire resistance of the FRP, safety and reliability of FRP reinforced concrete structures. 相似文献