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排序方式: 共有883条查询结果,搜索用时 31 毫秒
131.
Lisa J. White Sue J. Lee Kasia Stepniewska Julie A. Simpson Saw Lu Mu Dwell Ratree Arunjerdja Pratap Singhasivanon Nicholas J. White Francois Nosten Rose McGready 《Journal of the Royal Society Interface》2012,9(68):503-510
Many women in resource-poor settings lack access to reliable gestational age assessment because they do not know their last menstrual period; there is no ultrasound (US) and methods of newborn gestational age dating are not practised by birth attendants. A bespoke multiple-measures model was developed to predict the expected date of delivery determined by US. The results are compared with both a linear and a nonlinear model. Prospectively collected early US and serial symphysis-pubis fundal height (SFH) data were used in the models. The data were collected from Karen and Burmese women attending antenatal care on the Thai–Burmese border. The multiple-measures model performed best, resulting in a range of accuracy depending on the number of SFH measures recorded per mother (for example six SFH measurements resulted in a prediction accuracy of ±2 weeks). SFH remains the proxy for gestational age in much of the resource-poor world. While more accurate measures should be encouraged, we demonstrate that a formula that incorporates at least three SFH measures from an individual mother and the slopes between them provide a significant increase in the accuracy of prediction compared with the linear and nonlinear formulae also using multiple SFH measures. 相似文献
132.
Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor 总被引:1,自引:0,他引:1
Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo2O4 spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo2O4 spinel thin film exhibited a high specific capacitance value of 580 F g−1 and an energy density of 32 Wh kg−1 at the power density of 4 kW kg−1, accompanying with good cyclic stability. 相似文献
133.
Amita Singh Reena Yadav Gabriele Kociok-Köhn Manoj Trivedi Uday Pratap Azad Ashish Kumar Singh Abhinav Kumar 《International Journal of Hydrogen Energy》2018,43(12):5985-5995
In this work, four heteroleptic Ni(II)dppe dithiolates complexes, [Ni(NED)(dppe)] (Ni-NED), [Ni(ecda)(dppe)] (Ni-ecda), [Ni(i-mnt)(dppe)] (Ni-i-mnt) and [Ni(cdc)(dppe)] (Ni-cdc) (dppe = 1,2-bis(diphenylphosphino)ethane; NED = 1-nitroethylene-2,2-dithiolate; ecda = 1-ethoxycarbonyl-1-cyanoethyelene-2,2-dithiolate; i-mnt = 1,1-dicyanoethylene-2,2-dithiolate and cdc = cyanodithioimidocarbonate), have been synthesized and characterized by analytical and spectroscopic techniques (Elemental analysis, vibrational, electronic absorption and multinuclear NMR spectroscopy). Structural characterization of all the four complexes by single crystal X-ray diffraction study suggests distortion in regular square planar geometry at Ni(II) center by coordination with two phosphorus of the dppe and two sulfur of the dithiolate ligands, respectively. The decomposition of all four complexes have been done to produce nickel sulfides and the resulting nickel sulfides have been utilized for electrocatalytic oxygen evolution reaction (OER). The nickel sulfide obtained by decomposing Ni-cdc shows best activity with overpotential η = 222 mV at j = 10 mA cm?2 and a Tafel slope of 44.2 mV dec?1 while other catalysts shows η > 470 mV at j = 5 mA cm?2 and η > 600 mV at j = 10 mA cm?2 at loading of 1.3 mg cm?2. 相似文献
134.
Vinay G. Nadiger 《纺织学会志》2017,108(3):385-396
Silk is one of the important textile fibres used in apparel application. Since it is hygroscopic proteinous fibre, it is affected by microbes during usage and storage. Hence, antimicrobial treatment is desired to contain with this problem. Antimicrobial treatment is done using natural and synthetic agents. Nanoparticles have been added as antimicrobial agent for the application. In the present work, composite treatment of silk with Aloe Vera– a natural product and silver nanoparticles is done through crosslinking of 1,2,3,4-butane tetra carboxylic acid (BTCA) with silk in the presence of sodium hypophosphite (SHP). Effect of varying the concentration of BTCA, Aloe Vera and silver nanoparticles has been investigated. Untreated and treated silk fabrics have been characterized by FTIR, SEM and XRD to elucidate the effect of the treatment in terms of binding of Aloe Vera and silver nanoparticles, morphological changes and degree of crystallinity. Mechanical properties have been evaluated and analysed to illustrate the effect of the treatment. Further, the antimicrobial properties of the treated samples were evaluated against S. aureus (gram positive) and K. pneumoniae (gram negative) bacteria and the antimicrobial activity is found to be excellent. In order to assess the durability of the treatment, dry-cleaning has been done and subsequently antimicrobial properties have been assessed. Treated silk fabric samples after dry-cleaning upto 5 cycles exhibited satisfactory antimicrobial activity indicating that the treatment is durable in all the recipes. It is inferred that Aloe Vera chemically binds with silk through BTCA crosslinking while silver nanoparticles get adhesively bound or entrapped in the fibre matrix resulting in durable antimicrobial activity. 相似文献
135.
A Controlled Agitation Process for Improving Quality of Canned Green Beans during Agitation Thermal Processing
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Anika Singh Anubhav Pratap Singh Hosahalli S. Ramaswamy 《Journal of food science》2016,81(6):E1399-E1411
This work introduces the concept of a controlled agitation thermal process to reduce quality damage in liquid‐particulate products during agitation thermal processing. Reciprocating agitation thermal processing (RA‐TP) was used as the agitation thermal process. In order to reduce the impact of agitation, a new concept of “stopping agitations after sufficient development of cold‐spot temperature” was proposed. Green beans were processed in No. 2 (307×409) cans filled with liquids of various consistency (0% to 2% CMC) at various frequencies (1 to 3 Hz) of RA‐TP using a full‐factorial design and heat penetration results were collected. Corresponding operator's process time to impart a 10‐min process lethality (Fo) and agitation time (AT) were calculated using heat penetration results. Accordingly, products were processed again by stopping agitations as per 3 agitation regimes, namely; full time agitation, equilibration time agitation, and partial time agitation. Processed products were photographed and tested for visual quality, color, texture, breakage of green beans, turbidity, and percentage of insoluble solids in can liquid. Results showed that stopping agitations after sufficient development of cold‐spot temperatures is an effective way of reducing product damages caused by agitation (for example, breakage of beans and its leaching into liquid). Agitations till one‐log temperature difference gave best color, texture and visual product quality for low‐viscosity liquid‐particulate mixture and extended agitations till equilibration time was best for high‐viscosity products. Thus, it was shown that a controlled agitation thermal process is more effective in obtaining high product quality as compared to a regular agitation thermal process. 相似文献
136.
Rajesh Kumar Amit Pratap Singh Avinashi Kapoor K.N. Tripathi 《Journal of Modern Optics》2013,60(10):1471-1483
Dye-doped poly(vinyl alcohol) (PVA) waveguides have been fabricated and characterized. The waveguiding parameters of PVA film, for example the refractive index, thickness, birefringence, polarization conversion and propagation losses, were evaluated using the various concentration of dyes in polymeric solution. It has been shown that the dyes can affect the basic waveguiding parameters considerably. However, birefringence in PVA waveguides remains unaffected irrespective of any dyes and any concentration of dye used. 相似文献
137.
Vinay Jain Beena Rai Umesh V. Waghmare Venugopal Tammishetti Pradip 《Transactions of the Indian Institute of Metals》2013,66(5-6):447-456
Beneficiation of alumina rich iron ore slimes is a major challenge for the Indian iron ore industry. Considering the limits of gravity and magnetic separation processes in the relatively finer size range in terms of achieving adequate separation efficiency, selective flotation (with and without selective flocculation) of iron ore slimes, which is being used commercially in several countries for the beneficiation of iron ores, is worth exploring for the beneficiation of Indian iron ores. Based on the extensive work carried out in our laboratories, we have concluded that the design and development of highly selective reagents to achieve satisfactory separation of hematite and goethite from alumina containing minerals (gibbsite or kaolinite) in the ore and ore slimes, is the key to solving the challenging problem of processing alumina rich iron ores. Accordingly our research work has been focused on finding/designing selective reagents for iron oxide–gibbsite–kaolinite separation based on a molecular modeling computational approach developed by us for the design of mineral processing reagents. We present in this paper the results of our density functional theory computations to evaluate the interaction energies of a wide variety of different reagent functional groups such as carboxylic acid, hydroxamic acid, phosphonic acid, iminobismethyl phosphoric acid, xanthate and starch with hematite, gibbsite and kaolinite surfaces. Among all the reagents investigated so far, starch exhibits the highest selectivity towards the hematite surface with a difference in interaction energy of ~63 kcal/mol between hematite and gibbsite surfaces. Based on our earlier work which indicated polyvinyl pyrrolidone (PVP) to be more selective dispersant for kaolinite compared to conventional sodium silicate and sodium hexametaphosphate, we have investigated selective flocculation–dispersion of natural iron ore slimes (three different samples obtained from three different mines in India) with PVP and starch reagent combination. The results are promising. While the work is still in progress, the implications of our recent results are discussed in the context of the challenging problem of processing of alumina rich iron ore slimes in India. 相似文献
138.
We create a model which analyses the various risks involved in a food supply chain with the help of interpretive structural modelling (ISM). The various types of risks were identified based on a review of the literature and in consultation with experts in the food industry. The types of risks are clustered into five categories and risk mitigation is discussed. The model developed is validated with the help of a case study involving a food products manufacturing firm. 相似文献
139.
Kalpesh B. Sidhpuria Parimal A. Parikh Pratap Bahadur Raksh Vir Jasra 《Journal of Porous Materials》2008,15(4):481-489
Isomorphously nickel-substituted nano-crystalline ZSM-5 is synthesized in the absence of acidic aqueous fluoride medium incorporating
simple and low-cost metal inorganic salt precursor NiCl2.6H2O instead of large organic cationic salt like bis (tetraethyl ammonium) tetrachloronickelate (II) with less water quantity
to minimize the synthesis waste. PXRD, FT-IR, TG/DTG, XPS, UV–Vis DRS, SEM, TEM, ICP and N2 adsorption-desorption techniques were used to confirm the presence of nano-crystalline material having a MFI structure and
heteroatom substitution. The unit cell dimensions increase with increasing levels of nickel substitution. The crystallite
size of as synthesized samples was in the range of 60–75 nm, which increased to 60–160 nm after calcination at 550°C. Percentage
crystallinity and crystallite size increases with increasing nickel substitution level up to 0.17 mol and beyond that the
material becomes amorphous. 相似文献
140.
Xianxian Wu Nidia C. Gallego Cristian I. Contescu Vinay V. Bhat Mark C. Thies 《Carbon》2008,46(1):54-61
Palladium-doped activated carbon fibers are being evaluated as candidate materials for enhanced hydrogen storage at near ambient conditions. Pd-doped fibers were spun using a Pd salt mixed with an isotropic pitch precursor. Experimental techniques such as in situ X-ray analysis, thermogravimetric studies, scanning transmission electron microscopy and gas adsorption were employed to understand how processing conditions for the production of Pd-doped activated carbon fibers affect the microstructure, pore development, and dispersion of metal particles throughout the fibers. The results showed that PdO phase is present in the stabilized fibers and that this oxide phase is stable up to about 250 °C. The oxide phase transforms into Pd metal with increasing heat treatment temperature, going through the formation of an intermediate carbide phase. Sintering of Pd particles was observed with heat treatment at temperatures over 750 °C. It was also found that pore development during physical activation with CO2 was not significantly affected by the presence of Pd particles within the fibers. 相似文献