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排序方式: 共有338条查询结果,搜索用时 31 毫秒
11.
Silicon - Tuberose is native to Mexico and then reached Europe and spread other parts of the world. In Pakistan, tuberose stalks come in the market during late summer and autumn when only few... 相似文献
12.
Sadaqat Ali Bilal Anjum Ahmed Hafiz Muzammil Irshad Akolade Idris Bakare Abbas Saeed Hakeem Muhammad Qamaruddin Muhammad Ali Ehsan Sameer Ali Muhammad Umar Azam 《International Journal of Applied Ceramic Technology》2020,17(4):1948-1958
The thermomechanical behavior of micro/nano-alumina (Al2O3) ceramics reinforced with 1-5 wt.% of acid-treated oil fly ash (OFA) was investigated. Composites were sintered using spark plasma sintering (SPS) technique at a temperature of 1400°C by applying a constant uniaxial pressure of 50 MPa. It was evaluated that the fracture toughness of micro- and nanosized composites improved in contrast with the monolithic alumina. Highest fracture toughness value of 4.85 MPam1/2 was measured for the nanosized composite reinforced with 5 wt.% OFA. The thermal conductivity of the composites (nano-/microsized) decreased with the increase in temperature. However, the addition of OFA (1-5 wt.%) in nanosized alumina enhanced the thermal conductivity at an evaluated temperature. Furthermore, a minimum thermal expansion value of 6.17 ppm*K−1 was measured for nanosized Al2O3/5 wt.% OFA composite. Microstructural characterization of Al2O3-OFA composites was done by x-ray diffraction and Raman spectroscopy. Oil fly ash particles were seen to be well dispersed within the alumina matrix. Moreover, the comparative analysis of the nano-/microsized Al2O3/OFA composites shows that the mechanical and thermal properties were improved in nanosized alumina composites. 相似文献
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14.
Stability of fortified whole wheat flour (WWF) was evaluated using NaFeEDTA, elemental iron, ZnSO4 and ZnO as fortificants. Fortified WWF was stored in tin boxes and polypropylene bags for 60 days under ambient storage condition (ASC) and controlled storage condition (CSC). Fortification significantly (p ? 0.05) decreased moisture and protein content and increased ash content to 5.44%, 6% and 23%, as compared to control. Fortified WWF, assayed periodically for mould contamination manifested a significant inhibition (∼1 log reduction) in flours containing elemental iron. Low storage temperature and relative humidity (RH) indicated lower level of mould count during extended storage time. Tin boxes, as storage material, exhibited a better protection against mould attack, acting as an effective barrier for moisture. Fortificants exerted a slight deteriorative effect on texture characteristics of the chapattis made of these flours but chapattis were still accepted by the judges. Zinc fortificants seemed like having little or no effect on the quality of the flours and chapattis, made of such flours. Shelf life of fortified flour may be extended by using elemental iron as fortificant and storing the product in tin boxes under relatively low temperature and RH. 相似文献
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16.
Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering 相似文献
17.
Composites consisting of carbon fibers (CF) and carbon particles (CP) in polypropylene (PP) matrix were melt-compounded. Composites
were analyzed for their mechanical, electrical and thermal properties. Results indicate that the addition of these fillers
improved the mechanical properties of the composites. Thermal conductivity was enhanced as the concentration of fillers was
increased. Carbon fibers render the composites electrically conductive so we observed a percolation threshold near 10 wt.%
of CF for PP/CF (PP and CF composite) and near 25 wt.% of CP for PP/CP (PP and carbon particle composite). All the results
indicated that carbon fibers are more effective in improving the properties as compare to the carbon particles. 相似文献
18.
This article reviews the research and progress on polystyrene and nanoclay-based nanocomposite. Polystyrene is one of the most extensively used commercial polymers in the world. This review is designed to be an expansive source for polystyrene–clay nanocomposite research, including synthesis, characterization, structure/property relationship, manufacturing techniques, and applications considering thermal, mechanical, barrier, electrical conductivity, non-flammability, and biodegradability. The frequently used clays with polystyrene are montmorillonite, bentonite, hectorite, and kaolinite. The polystyrene–clay nanocomposite has several interesting commercial significances in packaging, automotive, fuel cell, construction, and electrical materials. Finally, future challenges toward the technical applications of these advance materials have been discussed. 相似文献
19.
Optically active polyorthoanisidine, polyorthotoluidine, polyorthoethylaniline and polyorthochloroaniline were synthesized with chemical polymerization of corresponding monomers in aqueous medium by using d- or l-camphorsulfonic acid (d- or l-CSA) as chiral dopant, ammonium persulfate as oxidant, and diaminodiphenylamine as initiator. By circular dichroism spectroscopic measurements, it was found that PANI exhibited generally a reversed chirality in comparison with the used chiral dopant, but the substituted PANIs had the same one as the chiral dopant. This revealed that the substituent at ortho position caused helical inversion of conformation in comparison with the parent PANI. Such effect was further confirmed by the influence of the copolymerization of aniline and its derivatives on the chirality of the copolymers. The effect of the substituent on the chirality of the copolymers was increased with the increase of the steric hindrance of the ortho substituent. A mechanism was proposed to explain the effects of steric hindrance on the chirality of PANIs. The clarified relationship between the steric hindrance and the chirality of the polymer can enable us to tailor the chiroptical properties of functional polymer materials for future application. 相似文献
20.
Interactive voice browsers offer an alternative paradigm that affords ubiquitous mobile access to the WWW using a wide range
of consumer devices. This technology can facilitate a safe, “hands-free” browsing environment that is of importance both to
car drivers and various mobile and technical professionals. This paper describes the challenges of architecting an interactive
voice browser that combines digital audio with the features of a speech synthesizer to make structural elements of the document
explicit to the listener. The aesthetics of the audio rendition can simultaneously help reduce the monotony factor and enhance
comprehension. The evolution of the voice browser gave rise to a new conceptual model of the HTML document structure and its
mapping to a 3D audio space. A number of novel features are discussed for improving both the user’s comprehension of the HTML
document structure and their orientation within it. These factors, in turn, can improve the effectiveness of the browsing
experience. 相似文献