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81.
Gaurav Goyal Anjana Dogra S. Rayaprol S.D. Kaushik V. Siruguri H. Kishan 《Materials Chemistry and Physics》2012
It has been observed that, compared to bulk form, the nanocrystalline α-Fe2O3 is finding application in various areas. Magnetic properties of α-Fe2O3 are found to be influenced by the size of particles and are also sensitive to synthesis method employed for sample preparation. In the present work we have prepared a series of Nd doped α-Fe2−xO3 samples (x = 0.0–0.5) by combustion method, without using any fuel. The analysis of room temperature neutron diffraction patterns shows that all the compounds of the series form in the hematite (α-Fe2O3) structure, space group R−3c. Magnetization measurements show that there is a broad distribution of particle size in the samples. We find that the increase in the Nd content results in the dilution of magnetism of α-Fe2O3. From results we believe that inclusion of Nd in α-Fe2O3 drastically modifies the magnetic properties. 相似文献
82.
We describe a method for determining the orientation of cytochrome c, RNase A, and lysozyme on silica nanoparticles (SNPs) using chemical modification combined with proteolysis-mass spectrometry. The proteins interacted with SNPs through preferential adsorption sites, which are dependent on SNP diameter; 4 nm SNPs induce greater structural stabilization than 15 nm particles, presumably due to greater surface curvature of the former. These results suggest that nanoparticle size and protein structure influence protein orientation on SNPs. 相似文献
83.
Rashmi Chourasia Ashish Bohre Ritu D. Ambastha O. P. Shrivastava P. K. Wattal 《Journal of Materials Science》2010,45(2):533-545
Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. The existence of cesium
containing NZP structure was determined on the basis of crystal data of solid solution. It was found that up to ~9.0 wt% of
cesium could be loaded into NZP formulations without significant changes of the three-dimensional framework structure. The
crystal chemistry of Na1−x
Cs
x
Zr2P3O12 (x = 0.1–0.4) has been investigated using General Structure Analysis System programming. The CsNZP phases crystallize in the
space group R-3c and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence
of R-factors. The unit cell volume and polyhedral (ZrO6 and PO4) distortion increase with rise in the mole% of Cs+ in the NZP matrix. The PO4 stretching and bending vibrations in the infrared region have been assigned. SEM, TEM, and EDAX analysis provide analytical
evidence of cesium in the matrix. 相似文献
84.
N. Gopakumar P. S. Anjana P. K. Vidyadharan Pillai 《Journal of Materials Science》2010,45(24):6653-6656
Cadmium selenide (CdSe) thin films of high crystalline quality on glass substrate have been prepared by chemical bath deposition
technique from an aqueous bath containing tetramine cadmium and sodium selenosulphate. Structural analysis using XRD shows
that the film is single phase, crystallized in hexagonal structure with preferred growth in (111) direction. The energy band
gap calculated from the absorption spectra of unannealed CdSe thin films shows an optical band gap of 1.8 eV and absorption
coefficient near band edge (α)—0.58 × 105 cm−1. The conductivity of CdSe thin films is n-type. 相似文献
85.
86.
Anjana Jain 《Polymer Engineering and Science》2008,48(2):211-215
The effect of in situ heating on the unit cell dimensions of crystalline aramid fiber (Twaron® fibers) has been studied in the temperature range 20–280°C. The changes in the unit cell dimensions have been used to estimate the coefficients of thermal expansion along the axial directions. On heating, the a and b axes expand, the coefficients of thermal expansion being αa = 35.84 × 10−6/°C and αb = 38 × 10−6/°C at room temperature. The c-axis contracts on heating, giving negative coefficient of thermal expansion αc = −5.38 × 10−6/°C at room temperature. Volume coefficient of thermal expansion αV however is positive, being 101.22 × 10−6/°C. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers 相似文献
87.
Positive temperature coefficient to resistivity characteristics of high density polyethylene (HDPE)/silver (Ag)‐coated glass bead (45 wt%) composites, without and with nanoclay, has been investigated with reference to HDPE/carbon black (CB) (10 wt%) composites. Plot of resistivity versus temperature of HDPE/CB (10 wt%) composites showed a sudden rise in resistivity (PTC trip) at ≈128°C, close to the melting temperature (Tm) of HDPE. However, for HDPE/Ag coated glass bead (45 wt%) composites, the PTC trip temperature (≈88°C) appeared well below the Tm of HDPE. Addition of 1 phr clay in the composites resulted in an increase in PTC trip temperature of HDPE/Ag‐coated glass bead (45 wt%) composites, whereas no significant effect of clay on PTC trip temperature was evident in HDPE/CB/clay composites. We proposed that the PTC trip temperature in HDPE/Ag‐coated glass bead composites was governed by the difference in coefficient of thermal expansion of HDPE and Ag‐coated glass beads. The room temperature resistivity and PTC trip temperature of HDPE/Ag‐coated glass bead (45 wt%) composites were found to be very stable on thermal cycling. Dynamic mechanical analyzer results showed higher storage modulus of HDPE/Ag‐coated glass bead (45 wt%) composites compared with the HDPE/CB (10 wt%) composites. Thermal stability of HDPE/Ag‐coated glass bead (45 wt%) composites was also improved compared with that of HDPE/CB (10 wt%) composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
88.
Asit B Mandal Sarabmeet Kaur Anurag K Johri Arumbackam V Elangovan Chandra Deo Harendra P Shrivastava 《Journal of the science of food and agriculture》2006,86(5):793-798
The influence of dietary levels of L ‐threonine (Thr) on growth and immune response was investigated in growing (0–5 weeks of age) Japanese quails (n = 288). Three dietary treatments were formulated using three levels of Thr [9.6, 10.2 and 11.2 kg?1 diet dry matter (DM)] at a fixed protein level of 233 g kg?1 and an energy level of 12.15 MJ (2900 kcal) metabolizable energy (ME) kg?1 feed dry matter. A metabolism trial with a 3‐day collection period was conducted at the third week of age employing all the birds. The cell‐mediated (using PHA‐P) and humoral (SRBC response) immune responses were measured at the fourth week of age. Carcass traits were assessed at the end of fifth week of age. Body weight gain was lower (P < 0.01) in birds received 9.6 g Thr kg?1 DM than in groups fed 10.2 g or 11.2 g kg?1 DM in the diet, but there was no significant difference in gain between the groups fed 10.2 or 11.2 g Thr kg?1 DM in the diet. Feed intake differed significantly owing to Thr levels being lowest (P < 0.05) at 9.6 g Thr kg?1 DM in the diet. Feed conversion ratio (FCR), protein efficiency and energy efficiency improved at the 11.2 g kg?1 level from 0 to 3 weeks of age; however, from 3 to 5 weeks of age, better FCR emanated from a diet with 9.6 g Thr kg?1 DM. The nitrogen balance did not differ (P > 0.05) with Thr level. Carcass traits, relative weight of immune organs and cell‐mediated (PHA‐P) and humoral (SRBC response) immune responses did not differ significantly (P > 0.05) as a result of the dietary treatments. Copyright © 2006 Society of Chemical Industry 相似文献
89.
In this study, a new sorbent, a poly(acrylamide‐co‐itaconic acid) [P(AAm‐co‐IA)]/activated charcoal (AC) composite, was prepared by the aqueous polymerization of acrylamide and itaconic acid in the presence of AC with N,N′‐methylene bisacrylamide as a crosslinker and potassium persulfate as an initiator. The P(AAm‐co‐IA)/AC composite sorbent showed a fair capacity to adsorb the cationic dye methylene blue. The maximum sorption capacity, as studied at 23, 37, and 50°C and determined with the Langmuir isotherm model, was found to be 909.0, 312.5, and 192.3 mg/g, respectively. For an initial concentration of 5 mg/L, the kinetic uptake data were studied with various kinetic models. The pseudo‐second‐order equation was found to fairly fit the uptake data with a regression value of 0.999. The dye uptake increased with the pH of the sorbate solution, and the optimum pH was found to be in the range of 7–10. Intraparticle diffusion was also observed to take place, and the coefficient of intraparticle diffusion was evaluated to be 26.51 × 10?2 mg g?1 min?1/2. The various thermodynamic parameters were also determined to predict the nature of the uptake process. The sorption process was found to be spontaneous, as indicated by a negative standard free energy change. The negative standard enthalpy change suggested an exothermic nature for the uptake. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
90.
Bhupendra Chudasama Anjana K. Vala Nidhi Andhariya R. V. Upadhyay R. V. Mehta 《Nano Research》2009,2(12):955-965
We describe a simple one-pot thermal decomposition method for the production of a stable colloidal suspension of narrowly
dispersed superparamagnetic Fe3O4-Ag core-shell nanostructures. These biocompatible nanostructures are highly toxic to microorganisms. Antimicrobial activity
studies were carried out on both Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Bacillus megaterium and Staphylococcus aureus) bacterial strains. Efforts have been made to understand the underlying molecular mechanism of such antibacterial actions.
The effect of the core-shell nanostructures on Gram negative strains was found to be better than that observed for silver
nanoparticles. The minimum inhibitory concentration (MIC) values of these nanostructures were found to be considerably lower
than those of commercially available antibiotics. We attribute this enhanced antibacterial effect of the nanostructures to
their stability as a colloid in the medium, which modulates the phosphotyrosine profile of the bacterial proteins and arrests
bacterial growth. We also demonstrate that these core-shell nanostructures can be removed from the medium by means of an external
magnetic field which provides a mechanism to prevent uncontrolled waste disposal of these potentially hazardous nanostructures.
相似文献