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排序方式: 共有1133条查询结果,搜索用时 31 毫秒
61.
Jagjeet Kaur Ravi Shrivastava Vikas Dubey Beena Jaykumar 《Research on Chemical Intermediates》2014,40(8):2599-2604
This paper reports thermoluminescence glow curves of Eu3+, Dy3+-doped Ba2MgSi2O7 phosphor for different UV exposure times. Kinetic data were evaluated by the peak-shape method. The glow curves shift toward higher intensity with increasing exposure time to UV at 365 nm. When the heating rate was 5 °C s?1, peaks were observed at 101.76, 109.69, 102.67, and 104.05 °C, respectively, after UV exposure for 5, 10, 15, and 20 min. The glow peaks are indicative of second-order kinetics. Different kinetic data, i.e. trap depth, order of kinetics, activation energy, and frequency factor were also calculated. To evaluate the persistence characteristics of the luminescence of the phosphor, the lifetime of the charge in the trap was calculated; it was 348, 660, 368, and 428 s for UV exposure of 5, 10, 15, and 20 min, which indicates the luminescence of the phosphor is persistent. 相似文献
62.
Ramandeep Kaur Heena Ripneel Kaur Aman Grover Susheela Rani Ashok Kumar Malik Abuzar Kabir Kenneth G. Furton 《Journal of separation science》2020,43(13):2626-2635
A simple, fast, and sensitive analytical protocol using fabric‐phase sorptive extraction followed by high performance liquid chromatography with ultraviolet detection has been developed and validated for the extraction of five parabens including methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. In the present work, sol‐gel polyethylene glycol coated fabric‐phase sorptive extraction membrane is used for the preconcentration of parabens (polar) from complex matrices. The use of fabric‐phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and overall decrease in the sample preparation time. Various factors affecting the performance of fabric‐phase sorptive extraction, including extraction time, eluting solvent, elution time, and pH of the sample matrix, were optimized. Separation was performed using a mobile phase consisting of water:acetonitrile (63:37; v/v) at an isocratic elution mode at a flow rate of 0.9 mL/min with wavelength at 254 nm. The calibration curves of the target analytes were prepared with good correlation coefficient values (r2 > 0.9955). The limit of detection values range from 0.252 to 0.580 ng/mL. Finally, the method was successfully applied to various cosmetics and personal care product samples such as rose water, deodorant, hair serum, and cream with extraction recoveries ranged between 88 and 122% with relative standard deviation <5%. 相似文献
63.
Salwinder Singh Dhaliwal Vivek Sharma Arvind Kumar Shukla Vibha Verma Manmeet Kaur Yashbir Singh Shivay Shahida Nisar Ahmed Gaber Marian Brestic Viliam Barek Milan Skalicky Peter Ondrisik Akbar Hossain 《Molecules (Basel, Switzerland)》2022,27(4)
Globally, many developing countries are facing silent epidemics of nutritional deficiencies in human beings and animals. The lack of diversity in diet, i.e., cereal-based crops deficient in mineral nutrients is an additional threat to nutritional quality. The present review accounts for the significance of biofortification as a process to enhance the productivity of crops and also an agricultural solution to address the issues of nutritional security. In this endeavor, different innovative and specific biofortification approaches have been discussed for nutrient enrichment of field crops including cereals, pulses, oilseeds and fodder crops. The agronomic approach increases the micronutrient density in crops with soil and foliar application of fertilizers including amendments. The biofortification through conventional breeding approach includes the selection of efficient genotypes, practicing crossing of plants with desirable nutritional traits without sacrificing agricultural and economic productivity. However, the transgenic/biotechnological approach involves the synthesis of transgenes for micronutrient re-translocation between tissues to enhance their bioavailability. Soil microorganisms enhance nutrient content in the rhizosphere through diverse mechanisms such as synthesis, mobilization, transformations and siderophore production which accumulate more minerals in plants. Different sources of micronutrients viz. mineral solutions, chelates and nanoparticles play a pivotal role in the process of biofortification as it regulates the absorption rates and mechanisms in plants. Apart from the quality parameters, biofortification also improved the crop yield to alleviate hidden hunger thus proving to be a sustainable and cost-effective approach. Thus, this review article conveys a message for researchers about the adequate potential of biofortification to increase crop productivity and nourish the crop with additional nutrient content to provide food security and nutritional quality to humans and livestock. 相似文献
64.
Anju Goyal Aditya Sharma Jasanpreet Kaur Sapna Kumari Madhukar Garg Rakesh K. Sindhu Md. Habibur Rahman Muhammad Furqan Akhtar Priti Tagde Agnieszka Najda Barbara Banach-Albiska Katarzyna Masternak Ibtesam S. Alanazi Hanan R. H. Mohamed Attalla F. El-kott Muddaser Shah Mousa O. Germoush Hamdan S. Al-malky Salman H. Abukhuwayjah Ahmed E. Altyar Simona G. Bungau Mohamed M. Abdel-Daim 《Molecules (Basel, Switzerland)》2022,27(3)
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67.
B. S. Randhawa K. J. Sweety Manpreet Kaur J. M. Greneche 《Journal of Thermal Analysis and Calorimetry》2004,75(1):101-111
Thermal analysis of some transition metal ferrimaleate precursors, M3[Fe(mal)3]2·xH2O (M=Mn, Co, Ni, Cu) has been studied in static air atmosphere from ambient to 600°C. Various physico-chemical techniques, i.e. TG, DTG, DTA, XRD, IR, Mössbauer spectrometry, have been employed to characterize both the intermediates and final products. After dehydration the anhydrous precursors undergo decomposition to yield an iron(II) intermediate, M[FeII(mal)2] (M=Mn, Co, Ni, Cu) in the temperature range 160-275°C. A subsequent oxidative decomposition of iron(II) species leads to the formation of -Fe2O3 and MO in the successive stages. Finally a solid-state reaction occurs between the oxides above 400°C resulting in the formation of transition metal ferrites, MFe2O4. The ferrites have been obtained at much lower temperature and in less time than in the conventional ceramic method.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
68.
Fructos MR Belderrain TR Nicasio MC Nolan SP Kaur H Díaz-Requejo MM Pérez PJ 《Journal of the American Chemical Society》2004,126(35):10846-10847
The complex IPrCuCl (1) catalyzes the transfer of the :CHCO2Et group from ethyl diazoacetate (EDA) to unsaturated and saturated substrates (olefins, amine, alcohols) with very high yields. In the absence of substrate, the complex 1 does not react with EDA to give the diazo coupling products (fumarate and maleate), a rare example in the field of metal-catalyzed diazocompounds decomposition. 相似文献
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70.
A metastable state, characterized by a low degree of mass localization, is identified using density-functional theory (DFT). This free energy minimum, located through the proper evaluation of competing terms in the free energy functional, is independent of the specific form of the DFT used. Computer simulation results on particle motion indicate that this heterogeneous state corresponds to the deeply supercooled state. 相似文献