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排序方式: 共有3174条查询结果,搜索用时 12 毫秒
101.
Imad Ibrahim Alicja Bachmatiuk Felix Börrnert Jan Blüher Ulrike Wolff Jamie H. Warner Bernd Büchner Gianaurelio Cuniberti Mark H. Rümmeli 《Carbon》2011,49(15):5029-5037
Single-crystal stable-temperature (ST)-cut quartz substrates, which have a (0 1 1 1) crystallographic plane with their surface normal lying close to 38° from the y axis ([0 1 0]), were annealed in air prior to use as a support for aligned carbon nanotube growth by chemical vapor deposition. Very smooth substrate surfaces were obtained with annealing times in the vicinity of 15 h at a temperature of 750 °C. These smooth surfaces are ideal for the growth of horizontally aligned SWCNTs with high spatial density, while less dense SWCNTs were obtained with less smooth surfaces. Under optimized growth conditions, only SWCNT are observed and they can grow to lengths in excess of 100 μm. Our findings suggest structural defects interfere with the growth process. A binary Fe/Co catalyst was employed to grow the nanotubes. No obvious dependence on the Fe:Co ratio is observed. 相似文献
102.
The free‐radical copolymerization of 2‐metil‐1‐{[(1‐{4‐[(4‐nitrobenzil)oksi]fenil}etilidene)amino]oksi}prop‐2‐en‐1‐on (NBOEMA) with methyl methacrylate (MMA) was carried out in 1,4‐dioxane at 65 ± 1°C. The copolymers were analyzed by Fourier transform infrared spectroscopy, 1H‐NMR, 13C‐NMR, and gel permeation chromatography (GPC). Elemental analysis was used to determine the molar fractions of NBOEMA and MMA in the copolymers and for the characterization of the compounds. The monomer reactivity ratios were calculated according to the general copolymerization equation with the Kelen–Tudos and Fineman–Ross linearization methods. The polydispersity indices of the polymers, determined with GPC, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of the copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperature of the copolymers increased with increasing NBOEMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Shimadzu TGA 60H thermogravimetric analysis thermobalance. All of the products showed moderate activity against different strains of bacteria and fungi. The photochemical properties of the polymers were investigated by UV spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
103.
The dynamics of a gas‐solid fluidized bed containing Geldart Group D particles mixed with a small proportion of Geldart Group B particles are investigated using pressure fluctuations data. Time series analysis, using a variety of nonlinear dynamics tools, shows that the slugging present with Group D particles can be suppressed by the addition of a small proportion of Group B particles. The power spectra and the auto‐correlation function are used for a preliminary evaluation of dominant slug frequencies. It is shown that the bed fluidized with the mixture of Group D and B particles behaves in a less periodic manner and is dominated by more random bubble motion. On the other hand, the correlation integral is used to analyze the chaotic behaviour of the flow, through evaluation of the fractal structure of the reconstructed attractors. It is shown that the bed fluidized with Group D particles is characterized by a combination of steady slug motion and irregular particles motion. The behaviour of the fluidized bed of Group D/B particles mixture is characterized by a single correlation dimension for a wide range of fluidization velocities. 相似文献
104.
Taofeek Mukaila Adewale Adeniyi Ibrahim Bello Niloy Chandra Sarker Ewumbua Monono Ademola Hammed 《应用聚合物科学杂志》2024,141(19):e55345
Plastic-induced environmental issues could be solved using biomaterials, such as polylactic acid (PLA) film. PLA film is a costly solution suggesting the need to add less expensive starch. However, PLA and starch do not mix due to their diverging water behavior. In this study, we evaluated the impact of lecithin as a compatibilizer in varying ratio of PLA and starch film. The results show that inclusion of lecithin in PLA/starch composite leads to enhanced mechanical properties compared with the composite without lecithin. All films' thermal properties were stable but the thermograph of PLA/starch display two peaks whose distance is impacted by lecithin. In addition, morphology and functional group fingerprints revealed that the addition of lecithin improved the interfacial adhesion between the two polymers. Lecithin influenced the positioning and dispersion pattern of starch granules and distinct transmittance characteristics. The improved compatibility of PLA/starch makes the resulting films less susceptible to water penetration and dissolution. This work demonstrated the possibility of using lecithin as emulsifier between PLA and starch which could expand the application of PLA/starch film especially in packaging industries and bale net wrapping. 相似文献
105.
Yee Li Kang Mei Yi Poon Purushothaman Monash Shaliza Ibrahim Pichiah Saravanan 《Korean Journal of Chemical Engineering》2013,30(10):1904-1910
A detailed surface characterizations and adsorption mechanism of Cd2+ on chemical activated carbon (CAC) prepared from Garnicia mangostana shell were investigated. The activation is accomplished in self-generating atmosphere using phosphoric acid as activating agent. The characterizations performed are elemental analysis, functional group identification, N2 adsorption isotherm and surface charges. Adsorption mechanism of metal ion was tested using Cd2+ as model ion. CAC achieved BET surface area of 1,498 m2/g with a mixture of micro and mesopores. The point of zero charge is observed to be at pH 2.8 and the optimum pH for Cd2+ adsorption on CAC is 12. The adsorption isotherm followed the Freundlich model, and the adsorption kinetics was explained by pseudo-second order kinetic model. From thermodynamic studies, the adsorption was found to be physical adsorption. X-ray photoelectron spectroscopy (XPS) confirmed the adsorption of Cd2+ onto CAC as +2 oxidation state. 相似文献
106.
A mathematical model of Green–Naghdi photothermal theory based on fractional-order of heat transfer is given to study the wave propagation in a two-d 相似文献
107.
Kazeem D. Adeyemi Abdulraheem Abdulrahman Sulyman O. Ibrahim Marili F. Zubair Olubunmi Atolani Abdulhammed A. Badmos 《European Journal of Lipid Science and Technology》2020,122(6)
The influence of dietary Tetracarpidium conophorum (African Walnut) seed meal (TCSM) on fatty acids, productivity parameters, and physicochemical properties of breast and thigh muscles in broiler chickens are assessed. A total of 180, 28‐d‐old Arbor acre broiler chickens are randomly assigned to dietary treatments containing 0% (control), 2.5%, and 5% w/w TCSM, fed for 28 d, and euthanized. Dietary TCSM reduces (p < 0.05) feed intake, body weight gain (BWG), carcass weight, and abdominal fat. Diet does not affect feed efficiency and hematological parameters. The control birds have higher (p < 0.05) serum total cholesterol and triglycerides than do the supplemented birds. Diet has no effect on pH, water holding capacity, carbonyl and malondialdehyde contents, and organoleptic properties of breast and thigh muscles. The 5% TCSM has higher redness in breast muscle than do other treatments. Dietary TCSM improves (p < 0.05) the concentration of C18:3n‐3 (4.80–8.76% vs 1.56%), C20:5n‐3 (0.54–0.79% vs 0.39%), C22:5n‐3 (0.64–0.89% vs 0.18%), and C22:6n‐3 (0.75–0.97% vs 0.19%), and reduces (p < 0.05) the fat content (2.15–2.45% vs 3.15%) in breast and thigh muscles. Dietary TCSM enhances muscle n‐3 fatty acids without instigating oxidative deterioration, but reduces BWG in broiler chickens. Practical Application: Albeit that broiler meat is rich in polyunsaturated fatty acids (PUFA), its omega 6 (n‐6)/omega 3 (n‐3) is >4. Elevated n‐6/n‐3 could have adverse effect on human physiology thereby promoting the pathogenesis of certain diseases. This heightens the need to enhance the n‐3 PUFA content of broiler meat. Dietary TCSM induced up to a fourfold increase in n‐3 PUFA content of the breast and thigh muscles in broiler chickens. Moreover, dietary TCSM induced up to a tenfold decrease in the n‐6/n‐3 of the breast and thigh muscles in broiler chickens. This finding assumes great significance because the health concerns regarding dietary fat are the foremost factors responsible for the bad image suffered by meat. These results provide insights on the potential of TCSM to improve the nutritional quality without compromising the oxidative shelf life, organoleptic traits, and physicochemical properties of broiler meat. 相似文献
108.
ABSTRACTIn this study, an Egyptian siliceous/calcareous sedimentary phosphorite was subjected to beneficiation by unsophisticated economic means. The mineralogical and chemical examination showed that the ore sample is a typical example for the East Mediterranean phosphorites with 21.80% P2O5, 10.93% acid insoluble and 16.61% loss on ignition. The primary crushed sample was classified into three size fractions without any milling and they were separately subjected to an integrated attrition scrubbing study. Screening and classification on the 2.30 mm and 0.071 mm sieves were sequentially introduced with the attrition process. The effect of solid%, attrition speed and time were studied and optimized for each size fraction. Results showed that three products were produced and could be categorized according to their P2O5 content into the coarse tailing (+2.30 mm), the attrition concentrate (?2.30 + 0.071 mm) and the phosphate fines (?0.071 mm). The P2O5 contents of these products reached 12.24%, 28.72% and 18.77%, with P2O5 distribution reached 6.74%, 51.75% and 41.51%, respectively. A global P2O5 of 28.72% was obtained with a recovery of about 52%. A tentative flow-sheet for the whole process was postulated. 相似文献
109.
Ibrahim Morad Xiaofeng Liu Jianrong Qiu 《Journal of the American Ceramic Society》2020,103(5):3051-3059
Tetra-valent manganese (Mn4+) has been regarded as an efficient non-rare-earth red-light emitting ion, which has stimulated continued search of robust hosts and efficient synthetic methods to stabilize Mn4+ centers with strong photoluminescence. In this work, we demonstrate a facile synthetic method for Mn4+ doped glass-ceramic (GC) based on crystallization-induced oxidation state change in an oxide glass. The parent glass with a formula of LiNaGe4O9 is fabricated by melt-quenching and crystallization is induced by thermal treatment in air. Oxidation of Mn2+ in glass to Mn4+ in the GC is confirmed by both optical spectroscopy and electron paramagnetic resonance (EPR) measurements. After thermal treatment, the characteristic reddish photoluminescence (PL) of Mn2+ in the glass centered at 611 nm disappears and a strong photoluminescence peak at 660 nm attributed to Mn4+ is observed. The conversion to Mn4+ after crystallization in the examined system may have strong implications for synthesis of Mn4+ doped phosphors which always requires rigorous control of the redox equilibrium during synthesis. 相似文献
110.
The aim of this study was to fabricate needle like‐TiO2/polyrhodanine nanostructures by polymerizing rhodanine monomer on the TiO2 nanoparticles' surfaces and investigate their antibacterial activities. The structural, thermal, morphological, surface and electrical properties of non‐covalently functionalized nanoparticles were characterized by using FTIR, XPS, elemental analysis, TGA, XRD, SEM‐EDX, TEM, contact angle, and conductivity measurements. Characterization results confirmed the formation of needle like‐TiO2/polyrhodanine (PRh) core/shell hybrid nanostructures. Alterations on the surface and electrokinetic properties of the materials were characterized by zeta (ζ)‐potential measurements with the presence of various salts and surfactants. The ζ‐potential of needle like‐TiO2 was observed to increase from ?7.6 mV to +28.4 mV after forming a core/shell needle like‐TiO2/PRh nanocomposite structure and with the presence of cetyltrimethyl ammonium bromide (CTAB) surfactant. Thereby colloidally more stable dispersions were formed. Antibacterial properties of needle like‐TiO2/PRh were also tested against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli by various methods and they showed good antibacterial activity. The highest killing efficiency was determined for needle like‐TiO2/PRh against E. coli by colony‐counting method as 0.95. TEM experiments also showed the immobilizations of the nanoparticles on E. coli and revealed the interactions between E. coli and the nanoparticles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41554. 相似文献