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101.
102.
Freeze-drying has received renewed interest in connection with biotechnology, food preservation and chemical industries. Freeze-drying under reduced pressure causes sublimation to occur. Simultaneous freezing of the moisture phase couples the two processes of freezing and sublimation and creates a self-driven process without need for any additional application of external energy other than that required to lower the surface temperature and pressure initially. A mathematical model consisting of coupled diffusion equations describing thermal and mass equilibrium in the solid-liquid and solid-vapour regions is solved analytically. The liquid-solid region is included with unknown freezing interfacial conditions. The effects of various parameters, such as conductivity ratio, latent heats, initial concentration, surface pressure and surface temperature, are examined with respect to the freezing and sublimation rates. The freezing rate is faster than the sublimation rate, though slower than the corresponding rate for constant freezing temperature. The freezing temperature is higher than the sublimation temperature for a constant composition ice pack. 相似文献
103.
Rahul Basu 《Calphad》1979,3(2):85-89
The compounds CdHgTe and its constituent binaries CdTe, HgTe, and CdHg are semiconductors which are used in thermal, infrared, nuclear, thermoelectric and other photo sensitive devices. The compound CdHgTe has a Sphaleritic structure of possible type A1IIB1IIC6VI. The TERCP program of Kaufman is used to estimate the stable regions of the ternary phase diagram using available thermodynamic data. It was found that there was little variation in stochiometry with temperature. The compositions were calculated for temperatures ranging from 325K to 100K and the compositional limits were Cd13?20Hg12?01Te75?79, Hg varying most. By comparison with a similar compound, Cd In2Te4 of forbidden band width. 88 to .90 e.V., similar properties are postulated for Cd1Hg1Te6 with applications in the infra red region of the spectrum at 300K where this composition is given by TERCP at the limit of stability. 相似文献
104.
Rahul Basu 《Calphad》1978,2(2):113-115
The quaternary system SbTeBiSe with small amounts of suitable dopants is of interest for the manufacture of thermoelectric modules which can produce the Peltier and Seebeck effect. This property could be useful in the preduction of energy from the thermoelectric effect. Other substances are Bismuth Telluride (Bi2Te3) and SbTeBi and compounds such as ZnIn2Se4. In the present paper, the application of computer programs such as MIGAP of Kaufman is used to indicate the stability of the ternary limits of SbTeBi within the temperature ranges of interest, namely 273 K to 300 K. 相似文献
105.
C. N. R. Rao A. Govindaraj Rahul Sen B. C. Satishkumar 《Materials Research Innovations》1998,2(3):128-141
Pyrolysis of organometallic precursors such as metallocenes and iron pentacarbonyl as well as of their mixtures with hydrocarbons
such as acetylene or benzene has been carried out under a variety of conditions to synthesize nanotubes. While the use of
benzene as a hydrocarbon source generally yields multi-walled nanotubes, it has been possible to obtain single-walled nanotubes
(∼1 nm diameter) by pyrolyzing a metallocene or a mixture of metallocenes along with acetylene under a high flow rate of Ar.
These experiments show that the organometallic precursor produces small nanoparticles of ∼1 nm diameter which then catalyze
the formation of the single-walled nanotubes. Copious quantities of aligned-nanotube bundles have been obtained by the pyrolysis
of acetylene in the presence of high concentrations of ferrocene. Nanorods have been produced by the pyrolysis of ferrocene
under vacuum. Single walled nanotubes can be filled or decorated by metals.
Received: 31 July 1998 / Accepted: 28 August 1998 相似文献
106.
Hailey S. Reynolds Rahul Ram Fiona A. Charalambous Frank Antolasic James Tardio Suresh Bhargava 《Minerals Engineering》2010,23(9):739-745
Uranium bearing ores are often a complex mixture of minerals and compounds, a number of which are not of economic importance and are commonly referred to as gangue materials. In order to improve the efficiency of the dissolution stage of the overall uranium extraction process, a greater understanding of the minerals and compounds present in the ore is required. A greater knowledge of the gangue materials present is important as they can influence various aspects of the dissolution process such as providing potential adsorption sites for aqueous uranium species and through influencing the equilibrium of reactions involving aqueous uranium species. In this study the mineralogy of a uranium ore was investigated using a range of X-ray diffraction (XRD) based methods including in situ high temperature XRD and XRD using a synchrotron beam line. The results obtained from standard XRD (Cu Kα), high temperature XRD and synchrotron XRD (16.534 keV) were compared and a number of minerals were identified. The improved spatial resolution and intensity of the synchrotron data allowed for superior phase identification of a variety of minerals where standard X-ray techniques gave inconclusive results. 相似文献
107.
Rapid lactate oxidase‐based assay for lactate content in milk to ascertain its hygienic quality 下载免费PDF全文
Brajesh Kumar Rajan Sharma Rahul Thakur Amit Kumar Barui Yudhishthir S Rajput Bimlesh Mann 《International Journal of Dairy Technology》2016,69(3):460-467
A rapid method for qualitative and quantitative assaying of l ‐lactate in milk is described. The method is based on oxidation of lactate by lactate oxidase with the simultaneous formation of H2O2 which subsequently oxidises 2, 4, 6‐tribromo 3‐hydroxy benzoic acid (TBHBA) in the presence of peroxidase. Oxidised TBHBA then reacts with 4‐amino antipyrine to obtain magenta colour (λmax = 523 nm). In the qualitative assay, colour change becomes visible in raw milk samples spiked with 300 mg lactate/L. The absorbance increases linearly up to 1000 mg/L. The method can be used for rapid assessment of the hygienic quality of milk. 相似文献
108.
109.
Annamalai Jeyakumari Mampuzha Sivadas Rahul Das Jaganath Bindu Chalil George Joshy Aliyamveetil Abubacker Zynudheen 《International Journal of Food Science & Technology》2016,51(7):1578-1585
The effect of an addition of shrimp protein hydrolysate and shrimp powder on the physicochemical properties of extruded snack was studied. Rice flour and cornflour were used as base materials, and extrusion was done using corotating twin‐screw extruder. A mixture response surface methodology was used to study the effect of ingredient mixture on the physical, functional and sensory properties of extrudates. Linear and quadratic mixture response regression model was fitted to the response variables, and it was evaluated using R2 values. Based on the desirability function score, the optimum combination of ingredient was 47.75% rice flour, 38.64% cornflour, 5.95% hydrolysate and 7.67% shrimp protein powder. It was observed that an addition of shrimp hydrolysate more than 5% (7.5%) improved the crispiness. Sensory evaluation revealed that shrimp hydrolysate and shrimp powder can be used at 5–7.5% level for developing protein‐rich extruded products without affecting sensory characteristics. 相似文献
110.
Song C Zaveri RA Shilling JE Alexander ML Newburn M 《Environmental science & technology》2011,45(17):7323-7329
Gas-particle partitioning theory is widely used in atmospheric models to predict organic aerosol loadings. This theory predicts that secondary organic aerosol (SOA) yield of an oxidized volatile organic compound product will increase as the mass loading of preexisting organic aerosol increases. In a previous work, we showed that the presence of model hydrophobic primary organic aerosol (POA) had no detectable effect on the SOA yields from ozonolysis of α-pinene, suggesting that the condensing SOA compounds form a separate phase from the preexisting POA. However, a substantial faction of atmospheric aerosol is composed of polar, hydrophilic organic compounds. In this work, we investigate the effects of model hydrophilic organic aerosol (OA) species such as fulvic acid, adipic acid, and citric acid on the gas-particle partitioning of SOA from α-pinene ozonolysis. The results show that only citric acid seed significantly enhances the absorption of α-pinene SOA into the particle-phase. The other two seed particles have a negligible effect on the α-pinene SOA yields, suggesting that α-pinene SOA forms a well-mixed organic aerosol phase with citric acid and a separate phase with adipic acid and fulvic acid. This finding highlights the need to improve the thermodynamics treatment of organics in current aerosol models that simply lump all hydrophilic organic species into a single phase, thereby potentially introducing an erroneous sensitivity of SOA mass to emitted OA species. 相似文献