Nanomaterials synthesis using natural sources is the technology to up come with advanced materials through extracts of plant, microorganisms, poultry waste etc. In this study, the authors report the synthesis of porous carbon nanotubes using high‐temperature decomposition technique facilitated by cobalt salt using chicken fats, a poultry waste as a precursor. Since chicken fats contain fatty acids which can decompose into short hydrocarbon chains and cobalt can act as the catalyst. The formation of carbon nanotubes was confirmed by Raman spectra, peaks at 1580 and 1350.46 cm−1 confirmed the graphite mode G‐band and structural imperfections defect mode D‐band, respectively. Transmission electron microscopy showed the formation of tube‐like structures. Nitrogen adsorption–desorption studies showed the high‐surface area of 418.1 m2 g−1 with an estimated pore diameter of 8.1 nm. Thermogravimetry analysis–derivative thermogravimetric analysis–differential thermal analysis showed the instant weight loss at 517°C attributed to the rapid combustion of nanotubes. A vibrating‐sample magnetometer showed the paramagnetic nature of the so‐formed carbon nanotubes formed.Inspec keywords: transmission electron microscopy, infrared spectra, nanomagnetics, pyrolysis, decomposition, adsorption, desorption, carbon nanotubes, differential thermal analysis, thermal analysis, nanofabrication, Raman spectra, X‐ray diffraction, scanning electron microscopy, paramagnetic materialsOther keywords: biogenic synthesis, highly porous carbon nanotubes, microorganisms, high‐temperature decomposition technique, cobalt salt, chicken fats, fatty acids, short hydrocarbon chains, Raman spectra, graphite mode G‐band, structural imperfections defect mode D‐band, transmission electron microscopy, paramagnetic nature, thermo‐magnetic properties, poultry waste, nitrogen adsorption‐desorption studies, thermogravimetry analysis, differential thermal analysis, carbon nanotubes, temperature 517.0 degC, C相似文献
The morphological, thermal and pasting properties of starch separated from potatoes of three varieties (Kufri Chandramukhi, Kufri Jyoti and Kufri Chipsona-2), treated either with CIPC (isopropyl N-(3 chlorophenyl) carbamate) or γ-irradiation (Co60, 0.1 and 0.5 kGy) and subsequently stored at 8, 12 and 16 °C for 90 days, were studied. Scanning electron microscopy (SEM) showed the presence of oval and irregular shaped starch granules with a diameter range of 15–16 μm. Mean granule size of starch separated from potatoes stored at 12 °C ranged from 18–25 μm and irradiation treatment resulted in an increase in the proportion of small size granules. The irradiation of potatoes with 0.5 kGy resulted in starch with significantly lower peak-, trough- and breakdown-viscosity as compared to starch from potatoes treated with either CIPC or 0.1 kGy irradiation. The irradiation of potatoes with 0.5 kGy caused a significant increase in setback and pasting temperature. Pasting temperature of starch was observed to vary with the storage temperature. Starch separated from potatoes stored at higher temperature showed lower pasting temperature and vice versa. The starch from potatoes stored at 8 °C showed higher peak-, trough- and breakdown-viscosity and lower setback. Peak viscosity increased and swelling volume decreased with increase in storage temperature. FTIR spectra showed that the starch from irradiated potatoes displayed a significant decrease in the intensity of the C–H stretch region between 2800 and 3000 cm−1, which was observed to be irradiation dose-dependent, and higher with 0.5 than 0.1 kGy. However, a slight broadening of O–H stretch (3000–3600 cm−1) in starches from irradiated potatoes was observed. The spectral changes caused by γ-irradiation were apparent in the O–H stretch (3000–3600 cm−1), C–H stretch (2800–3000 cm−1) and bending mode of water (1600–1800 cm−1). 相似文献
Two types of environmental barrier coatings for silicon nitride are investigated. In Type A coatings, a bilayer of polymer-derived SiCN and zirconia was deposited on silicon nitride. This coating nearly completely suppressed oxidation of Si3N4 at 1350°C in a 900 h-long test. But the coating volatilized in a streaming water vapor environment. In Type B coatings, a topcoat of hafnia was built on to the SiCN coating with an intermediate compliant layer to accommodate the thermal expansion mismatch between hafnia and Si3N4. The three-layer design was successful in preventing both oxidation as well as weight loss in the silicon nitride at temperatures up to 1300°C. The compliant interlayer was made from a porous microstructure, which approximately followed the guidelines subscribed by a model based on the columnar design. The results lead to both expected and unexpected findings. The three-layer design used to accommodate thermal expansion followed the prediction from the model. But the suppression of oxidation by the SiCN and zirconia overlayer, in Type A coatings, was unexpected. Inhibition of oxygen diffusion by zircon, which appears to have formed by a reaction between SiCN and zirconia, is one possible explanation. Another explanation is that ionic diffusion of oxygen in zircon overlayer and the molecular diffusion of oxygen through the silica interlayer just below creates an electrical field, which opposes ionic diffusion of oxygen through zircon. 相似文献
Polystyrene‐supported gold (Au@PS) nanoparticles were synthesized by the reduction deposition approach and well characterized by UV‐visible, XRD, TEM, SAED, EDX, and XPS studies. The Au@PS was applied as catalyst for the hydration of nitriles to amides in water under microwave irradiation. Several functionalized aromatic, heterocyclic and aliphatic nitriles were found to be active for synthesis of the corresponding amides where no activation of water by base, ligand and support is needed. Easy recovery, negligible leaching and recyclability for up to eight runs are added advantages of the catalyst under water‐mediated reaction conditions.
Summary The research described in this communication was undertaken to test the hypothesis that the fluid mechanics and heat-transfer aspects involved in aseptic processing could be modelled. In order to do this, a finite difference FORTRAN program (using the fourth-order, four-stage explicit Runge–Kutta method) was written by the authors to compute the velocity of fluid elements and particles during fully 3-dimensional flow in conventional and helical-holding tubes. The effect of particles on the fluid-flow field and the interaction between particles was taken into account during the modelling. Simulation results showed that an increase in specific gravity, tube diameter or coil diameter resulted in an increase in the residence time of the particles, while an increase in the flow rate decreased the residence time of the particles. An increase in the particle diameter or the flow rate narrowed the Residence Time Distribution (RTD) of the particles, while an increase in specific gravity or the tube diameter increased the RTD of the particles. 相似文献
A method is presented for conservatively transferring, or remapping, cell-centered variable fields from one mesh to another with second-order accuracy. The method is generally applicable to any polyhedral source or target mesh. Like the work of Farrell et al. [1], which was designed for finite-element computations, the proposed methodology uses a logical supermesh consisting of the intersections of polyhedra from both meshes. The resulting transfer process is well-suited for finite-volume methods that rely on cell-centered variables. The accuracy and efficacy of the new remapping process is demonstrated with numerical experiments and a computational fluid dynamics test. 相似文献
The risks/benefits of anemia treatment in dialysis patients have been redefined in the US Epoetin α label. This analysis was carried out to determine if increasing hemoglobin (Hb) levels improve exercise tolerance and physical function in anemic dialysis patients. This is a new analysis of the Canadian Erythropoietin Study Group trial, a double‐blind, randomized, placebo‐controlled trial in dialysis patients. Subjects were 18 to 75 years old, on hemodialysis for >3 months, and had a baseline Hb <9.0 g/dL. Patients with a history of diabetes mellitus, ischemic heart disease, or severe/uncontrolled hypertension were excluded. Patients were randomized to receive Epoetin α to a target Hb of 9.5 to 11.0 g/dL (n=40) or a target of 11.5 to 13.0 g/dL (n=38), or receive placebo (n=40). Results from patients in the Epoetin‐α–treated arms were combined for this analysis. Hb level, exercise tolerance (Treadmill Stress Test and 6‐Minute Walk Test) and patient‐reported physical function measures (Physical Summary domain from the Kidney Disease Questionnaire, and 4 domains from the Sickness Impact Profile) were reported at baseline and months 2, 4, and 6. Differences in measures were statistically significant for exercise tolerance (Treadmill Stress, P=0.0001) and patient‐reported physical function (Kidney Disease Questionnaire Physical, P=0.0001; Sickness Impact Profile Physical, P=0.0015) across all time points for Epoetin‐α–treated patients compared with placebo. Improvements were seen at 2 months and were maintained through months 4 and 6. Dialysis patients receiving Epoetin α showed improved exercise tolerance and physical function. These findings should be considered as physicians weigh the risks and benefits of treatment. 相似文献
In this paper we have developed a second generation wavelet based finite element method for solving elliptic PDEs on two dimensional
triangulations using customized operator dependent wavelets. The wavelets derived from a Courant element are tailored in the
second generation framework to decouple some elliptic PDE operators. Starting from a primitive hierarchical basis the wavelets
are lifted (enhanced) to achieve local scale-orthogonality with respect to the operator of the PDE. The lifted wavelets are
used in a Galerkin type discretization of the PDE which result in a block diagonal, sparse multiscale stiffness matrix. The
blocks corresponding to different resolutions are completely decoupled, which makes the implementation of new wavelet finite
element very simple and efficient. The solution is enriched adaptively and incrementally using finer scale wavelets. The new
procedure completely eliminates wastage of resources associated with classical finite element refinement. Finally some numerical
experiments are conducted to analyze the performance of this method. 相似文献