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排序方式: 共有362条查询结果,搜索用时 15 毫秒
81.
Suman Labala Praveen Kumar Mandapalli Shubhmita Bhatnagar 《Drug development and industrial pharmacy》2015,41(8):1302-1310
Objective: The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods.Materials and methods: In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9.Results and discussion: Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0?±?0.6?μm and 8.1?±?1.9?mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (–)7.4?±?0.7?mV and (–)5.7?±?1.0?mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2?M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120?h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment.Conclusion: In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery. 相似文献
82.
Rohit R. Shahi Ashish Bhatnagar Sunita K. Pandey Viney Dixit O.N. Srivastava 《International Journal of Hydrogen Energy》2014
The present investigations are focused on the effect of different Ti-based catalysts (Ti, TiO2, TiCl3 and TiF3) on de/re-hydrogenation characteristics of nanocrystalline MgH2. Desorption temperature of milled MgH2 lowers from 380 to 350, 340, 310 and 260 °C with the addition of Ti, TiO2, TiCl3 and TiF3 respectively. The rehydrogenation characteristics are also improved through the deployment of Ti-based catalysts. Among all Ti based additives, TiF3 is found to be the most effective catalyst for hydrogen sorption from nano MgH2. The better catalytic effect of TiF3 over other Ti-based catalyst can be explained on the basis of temperature programmed reduction (TPR) studies. TPR experiments performed for different Ti additives, reveals that there is no oxidation/reduction reaction below 400 °C except for TiF3. The TPR profile of TiF3 shows some oxidation/reduction reaction exhibits at 200 °C. In order to further improve the sorption characteristics and cyclability of TiF3 catalyzed nano MgH2, we have investigated the effect of SWCNTs in MgH2+TiF3 sample. De/rehydrogenation characteristics reveal the synergistic effect of SWCNTs and TiF3 in MgH2+TiF3 sample. The details of the improvement in sorption behavior of MgH2–TiF3 in presence of SWCNTs are described and discussed. 相似文献
83.
Braj Gaurav Sharma Kushagra Khanna Neeraj Kumar Dhruv K. Nishad Mitra Basu Aseem Bhatnagar 《Drug development and industrial pharmacy》2017,43(11):1759-1769
Calcium chloride is an essential calcium channel agonist which plays an important role in the contraction of muscles by triggering calcium channel. First time hypothesized about its role in the treatment of GER (gastro-esophageal reflux) and vomiting disorder due to its local action. There are two objectives covered in this study as first, the development and optimization of floating formulation of calcium chloride and another objective was to evaluate optimized formulation through gamma scintigraphy in human subjects. Gastro retentive formulation of calcium chloride was prepared by direct compression method. Thirteen tablet formulations were designed with the help of sodium chloride, HPMC-K4M, and carbopol-934 along with effervescing agent sodium bicarbonate and citric acid. Formulation (F8) fitted best for Korsmeyer–Peppas equation with an R2 value of 0.993. The optimized formulation was radiolabelled with 99mTc-99?m pertechnetate for its evaluation by gamma scintigraphy. Gastric retention (6?h) was evaluated by gamma scintigraphy in healthy human subjects and efficacy of present formulation confirmed in GER positive human subjects. Gamma scintigraphy results indicated its usefulness in order to manage GERD. Stability studies of the developed formulation were carried out as per ICH guidelines for region IV and found out to be stable for 24?months. 相似文献
84.
Preeti Verma Poornendu Chaturvedi J. S. B. S. Rawat Manohar Kumar Surendra Pal Mahesh Bal D. S. Rawal Harsh Hanuman Prasad Vyas Partha Ghosal P. K. Bhatnagar 《Journal of Materials Science: Materials in Electronics》2007,18(6):677-680
Activation of abnormal emitting sites in Carbon Nano Tube (CNT) field emitters and their elimination is reported. CVD grown,
patterned CNT was used as cathode for field emission studies. We encountered the problem of current non-uniformity in CNT
cathode. This non-uniformity was attributed to abnormally active emitting sites during voltage ramp-up. The sudden increase
in current resulted in region of positive slope in F–N curve, which can’t be explained by conventional F–N theory. Also the
grown CNTs can be a mixture of metallic and semi conducting nature, which may cause deviation from the conventional F–N theory.
We could eliminate abnormally active sites by electric field treatment, thereby increasing current uniformity and stability.
The work is underway to understand the deviation in FN curve at high fields. 相似文献
85.
Biomass has been recognized as a major world renewable energy source to supplement declining fossil fuel sources of energy. Biomass derived transportation fuels have not only the potential to replace conventional fuels but can also be utilized as blending components for improving the quality of these fuels. The biocrude obtained from Euphorbia antisyphilitica, identified as the most potential petrocrop was investigated as a potential source for liquid fuels. The feed was studied for yield conversion data under different catalyst to feed ratio at various temperatures. Maximum middle distillates selectivity was observed at catalyst/oil ratio 4 and 6 and reaction temperature 500 °C. The main constituents of the gaseous products are C3, C4 and C5. The liquid fuels are highly aromatic with low olefinic content. 相似文献
86.
Poly(vinyl chloride) (PVC)-based membranes of pyrimidines, 1-(2′-aminoaryl)-4, 4, 6-trimethyl-1, 4, 5, 6-tetrahydro-6-hydroxypyrimidine-2-thiol
(HPT) (R = −H, −CH3, −OCH3) with sodium tetraphenylborate (NaTPB) as an anion inhibitor and dibutylphthalate (DBP), dioctylphthalate (DOP), dibutyl
(butyl) phosphonate (DBBP) and 1-chloro naphthalene (CN) as plasticizing solvent mediators were prepared and used as Hg2+ selective electrodes. Optimum performance was observed with the membrane having HPT(−OCH3)−PVC−NaTPB−DOP in the ratio 1:33:1:65 (w/w). The electrode works well over a wide concentration range 5.0 × 10−6−1.0 × 10−1 M (detection limit 1.0 ppm) with Nernstian compliance (29.5 mV decade−1) between pH 2.5 and 4.0 with a fast response time of about 20 s. The selectivity coefficient values of the order of 0.001
for mono-, bi- and trivalent cations, indicate high selectivity for Hg2+ ions over these cations. Further, anions such as Cl− and SO
4
2−
do not interfere in the functioning of Hg2+ sensor. The electrodes were used over a period of five months with good reproducibility (std. dev. ±0.2 mV) and the performance
of the electrodes was found satisfactory even up to 10% nonaqueous medium. The electrode assembly was also evaluated for potentiometric
determination of Hg2+. 相似文献
87.
Shivani Dhall Manasvi Kumar Mehar Bhatnagar B.R. Mehta 《International Journal of Hydrogen Energy》2018,43(37):17921-17927
In the present work, role of palladium (Pd) and tin oxide (SnO2) nanoparticles (NPs) deposited on graphene has been investigated in terms of dual gas sensing characteristics of ethanol and H2 between two temperatures. The incorporation of nanoparticles into graphene has been observed which results a large change in the sensing response towards these gases. It is investigated that, incorporation of isolated Pd NPs on the graphene facilitates the room temperature sensing of H2 gas with fast response and recovery time whereas, isolated SnO2 NPs on graphene enables the detection of ethanol at 200 °C. However, combination of isolated Pd and SnO2 NPs on graphene shows improved sensitivity and good selectivity towards H2 and ethanol, usually not observed in chemiresistive gas sensors. Catalytic PdH interaction and corresponding change in work function of nanoparticles on hydrogenation resulting in modifications in electronic exchange between Pd, SnO2 and graphene are responsible for the observed behavior. These results are important for developing a new class of chemiresistive type gas sensor based on change in the electronic properties of the graphene and NPs interfaces. 相似文献
88.
89.
Rajesh Kumar Chandra K. Singh Suchitra Kamle Rajeshwar P. Sinha Raj K. Bhatnagar Devendra N. Kachru 《Food chemistry》2010
Vegetative insecticidal protein (Vip) is now being used for transgenic expression in several crops; conferring resistance against lepidopteron pests. A rapid, single step, sensitive and specific immunochromatographic (IC) strip test for the detection of recombinant Vip-S protein in the transgenic samples was developed. Polyclonal rabbit anti-Vip-S IgG conjugated to nanocolloidal gold served as a probe to detect Vip protein in test samples. The detection limit for the developed IC strip was 100 ng/ml (100 ppb) and on addition of gold enhancer the sensitivity increased to 1 ng/ml (1 ppb) of Vip-S protein. The assay was validated with transgenic brinjal samples. The assay time was less than 10 min, suitable for rapid on-site testing. No cross-reactivity was observed with other transgenic plant proteins employed for pest and weed management, i.e. Cry1Ac, Cry1Ab, and CP4-EPSPS. This on-site test offers rapid screening for a genetically modified crops having relatively new transgene (vip) entering the global market. 相似文献
90.
Bhatnagar M.R. Hjorungnes A. Song L. 《Wireless Communications, IEEE Transactions on》2009,8(8):3985-3995
In this paper, we propose a maximum likelihood (ML) decoder for differentially encoded full-rank square nonorthogonal space-time block codes (STBCs) using unitary or non-unitary signal constellations, which is also applicable to fullranked orthogonal STBC (OSTBC). As the receiver is jointly optimized with respect to the channel and the unknown data, it does not require any knowledge of channel power, signal power, or noise power to decode the signal, and the decision is purely based on two consecutively received data blocks. We analyze the effect of channel correlation on the performance of the proposed system in Rayleigh fading channels. Assuming a general correlation model, an upper bound of the pair-wise error probability (PEP) of the differential OSTBCs is derived. An approximate bound of the PEP for the differential nonorthogonal STBCs is also derived. We propose a precoder designing criterion for differential STBC over arbitrarily correlated Rayleigh channels. Precoding improves the system performance over the correlated Rayleigh MIMO channels. Our precoded differential codes differ from the previously proposed precoder designs for differential OSTBC in the following ways: 1) We propose a precoder design for arbitrarily correlated Rayleigh channels, whereas the previous work considers only for transmit correlation. 2) The previous work is only applicable to the OSTBCs with PSK constellations, whereas our precoder is applicable to any type of full-rank square STBCs with unitary and non-unitary signal constellations. 相似文献