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Effect of Surface Roughness on Laser Induced Nonlinear Optical Properties of Annealed ZnO Thin Films

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Journal of Materials Science & Technology 2012年第6期28卷 506-511页

作者： Vinay kumari Vinod Kumar Devendra Mohan purnima B.P.Malik R.M.Mehra Department of Physics BMIETSonepat 131001India Department of Physics DCRUSTMurthal 131027India Materials Science Group Inter University Accelerator CentreAruna Asaf Ali MargNew Delhi 110067India Department of Applied Physics GJUS&THisar 125001India School of Engineering and Technology Sharda UniversityGreater Noida 201306India

Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature （TA） was reported. The films were characterized by X-ray diffraction （XRD）, UV-Vis-NIR transmission and single beam z-scan technique using second harmonics of Nd：YAG laser. Surface morphology of the samples was investigated by atomic force microscopy （AFM）. Surface roughness was found minimum （8.4 nm） for ZnO sample annealed at 450℃. The nonlinear optical properties （NLO） were found to be dependent on surface roughness and the highest value of third order nonlinear susceptibility （X（3）=4.3x 10-7 esu） was obtained for ZnO at TA 450℃.

关键词： ZnO films Sol-gel Annealing temperature Nonlinear optical properties Thirdorder nonlinear susceptibility z-scan

Largest Ediacaran discs from the Jodhpur Sandstone, Marwar Supergroup, India: Their palaeobiological significance

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Geoscience Frontiers 2014年第2期5卷 183-191页

作者： purnima Srivastava Centre of Advanced Study in Geology Lucknow University

Ediacaran discs from the Jodhpur Sandstone of the Marwar Supergroup, Rajasthan, exhibit a wide size ranging from a few millimetres to 75 cm in diameter. Exceptionally large size of the discs in these rocks represent the largest reported so far from any Ediacaran assemblage. Although, larger medu-soid discs have been reported from USA, they are from the middle Cambrian and even younger rocks. Presence of microbial mats and weed-like structures with well preserved hold fasts and horizontal rhizome-like structures in association with some of these large-sized discs support their animal affinity, which probably feed on this weed-like vegetations. This association also supports their benthic habitat. Unlike the general trend of sudden increase in size of organisms in Ediacaran period and further decrease in size during Cambrian, these discs continued increasing in size in Cambrian also.

关键词： Ediacaran discs Jodhpur Sandstone Marwar Supergroup Rajasthan India

A p-silicon nanowire/n-ZnO thin film heterojunction diode prepared by thermal evaporation

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Journal of Semiconductors 2014年第1期35卷 22-26页

作者： purnima Hazra S.Jit Department of Electronics Engineering Indian Institute of Technology (BHU)

This paper represents the electrical and optical characteristics of a SiNW/ZnO heterojunction diode and subsequent studies on the photodetection properties of the diode in the ultraviolet （UV） wavelength region. In this work, silicon nanowire arrays were prepared on p-type （100）-oriented Si substrate by an electroless metal deposition and etching method with the help of ultrasonication. After that, catalyst-free deposition of zinc oxide （ZnO） nanowires on a silicon nanowire （SiNW） array substrate was done by utilizing a simple and cost-effective thermal evaporation technique without using a buffer layer. The SEM and XRD techniques are used to show the quality of the as-grown ZnO nanowire film. The junction properties of the diode are evaluated by measuring current-voltage and capacitance-voltage characteristics. The diode has a well-defined rectifying behavior with a rectification ratio of 190 at -t-2 V, turn-on voltage of 0.5 V, and barrier height is 0.727 eV at room temperature under dark conditions. The photodetection parameters of the diode are investigated in the bias voltage range of ± 2 V. The diode shows responsivity of 0.8 A/W at a bias voltage of 2 V under UV illumination （wavelength = 365 nm）. The characteristics of the device indicate that it can be used for UV detection applications in nano-optoelectronic and photonic devices.

关键词： silicon nanowire ZnO nanowire heterojunction diode interface barrier height photo responsivity

Continuous melt granulation to develop high drug loaded sustained release tablet of Metformin HCl

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Asian Journal of Pharmaceutical Sciences 2017年第1期12卷 37-50页

作者： Pradnya Vaingankar purnima Amin Department of Pharmaceutical Sciences and Technology Institute of Chemical Technology University under Section 3 of UGC Act–1956 Elite Status and Centre of Excellence–Government of Maharashtra

The present work explores the application of melt granulation technology to develop a high drug loaded sustained release matrix tablet of Metformin HCl using hydroxypropylcellulose(HPC) as a hydrophilic binder and stearic acid as an extrusion aid for producing cohesive granules. This novel approach allowed the use of a minimum number of excipients to reduce the tablet size, and to enhance compressibility of the drug. This also offered a cost effective method owing to the elimination of a ‘drying step’ prevalent in wet granulation ***, this research also focuses on resolving the processability issues associated with the use of HPC Nisso-H at high drug loading. The thermal lubricants were screened for this purpose and evaluated for their impact on extrudability, granule and tablet characteristics. Stearic acid was selected as the thermal lubricant, which not only contributed to the inhibition of burst release, but also improved the flow property of the *** developed matrix tablet(75% drug loading) resulted in 670 mg of weight for 500 mg dose strength and showed sustained drug release over 10 h. When compared, with conventional granulation techniques, it was observed that, under identical compression force, the tablet prepared by MG exhibited superior compactibility along with tablet hardness and optimal drug release profile. FTIR suggested nonexistence of chemical interaction between the drug and the other excipients while XRD and DSC analysis revealed the crystalline state of the ***, the results obtained from Raman spectroscopy proved the uniform distribution of the Metformin HCl and polymer in the final dosage form. This technology leads to the manufacture of sustained release matrix formulation with reduced tablet size of a high dose,highly water soluble drug otherwise difficult to process using standard batch-granulation.

关键词： Metformin hydrochloride Hydroxypropylcellulose High drug loaded tablet Melt granulation

Synergistic Effect of Metal Nanoparticles on the Antimicrobial Activities of Antibiotics against Biorecycling Microbes

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Journal of Materials Science & Technology 2016年第6期32卷 524-532页

作者： Chandni Khurana purnima Sharma O.E Pandey Bhupendra Chudasama Laboratory of Nanomedicine School of Physics and Materials ScienceThapar UniversityPatiala 147004India Department of Applied Sciences Chandigarh UniversityMohali 160055India Department ofBiotechnology Thapar UniversityPatiala 147004India

Biorecycling microbes, which have critical functionalities in natural cycles, are essential to sustain eco-system of the earth. Any alterations in these cycles caused by the mutations of microbes could be a potential threat to life on earth. Antibiotics leached from pharmaceutical waste, animal food and agribusiness prod- ucts are accumulating in the environment. Metal nanoparticles are also accumulating in environment because of their extensive use as biocidal agent in domestic products. Interaction of antibiotics and metal nanoparticles with eco-ffiendly microorganisms has a potential to alter the ecosystem of the earth. In this article, we have studied the antibacterial activities of silver and copper nanoparticles and their for- mulations with antibiotics, tetracycline, and kanamycin against biorecycling microbes, Bacillus subtilis and Pseudomonas fluorescens. Strong synergistic effect of metal nanoparticles on the antimicrobial ac- tivities of commercial antibiotics has been observed. Antimicrobial activity of tetracycline improves by 286%-346% and 0%-28% when being tested in the presence of 250 ppm of silver and copper nanoparticles, respectively. For kanamycin, the improvement is 154%-289% for silver and 3%-20% for copper nanoparticles. Irrespective of the antibiotics and tested organisms, synergy is more prominent for silver nanoparticles even at their minimum active concentration （100 ppm）. This study demonstrates that the combination of metal nanoparticles with antibiotics could be more fatal to ecosystem than either the metal nanoparticles or the antibiotics alone.

关键词： Synergy Nanoparticles Antibiotics Biorecycling microbes Antibacterial activities

Comparative response of seedlings of selected native dry tropical and alien invasive species to CO_(2) enrichment

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Journal of Plant Ecology 2009年第2期2卷 69-75页

作者： purnima Raizada Anamika Singh A.S.Raghubanshi Ecosystems Analysis Laboratory Centre of Advanced Study in BotanyBanaras Hindu UniversityVaranasi 221005Uttar PradeshIndia Department of Botany Punjab UniversityChandigarh 160014PunjabIndia

Global climate change and ongoing plant invasion are the two prominent ecological issues threatening biodiversity world *** invasive species,Lantana camara and Hyptis suaveolens are the two most important invaders in the dry deciduous forest in *** monitored the growth of these two invasive species and seedlings of four native dry deciduous species(Acacia catechu,Bauhinia variegata,Dalbergia latifolia and Tectona grandis)under ambient(375–395μmol mol^(-1))and elevated CO_(2)(700–750μmol mol^(-1))to study the differential growth response of invasive and native *** Seedlings of all the species were exposed to ambient and elevated CO_(2).After 60 days of exposure,seedlings were harvested and all the growth-related parameters like plant height;biomass of root,stem and leaves;total seedling biomass;R/S ratio;allocation parameters;net assimilation rate(NAR)and relative growth rate(RGR)were *** Findings Biomass,RGR and NAR of all the species increased under elevated CO_(2)but the increase was higher in invasive species and they formed larger seedlings than *** under the CO_(2)-enriched future atmosphere,competitive hierarchies could change and may interfere with the species composition of the invaded area.

关键词： dry deciduous seedlings elevated CO_(2) global change plant invasion

Nanotechnology for colorectal cancer detection and treatment

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World Journal of Gastroenterology 2022年第46期28卷 6497-6511页

作者： purnima Gogoi Geetika Kaur Nikhlesh K Singh Integrative Biosciences Center OVASWayne State University School of MedicineDetroitMI 48202United States

Colorectal cancer(CRC)is the third most diagnosed cancer and the second leading cause of cancer-related mortality in the United *** the globe,people in the age group older than 50 are at a higher risk of *** and environmental risk factors play a significant role in the development of *** detected early,CRC is preventable and ***,available screening methods and therapies for CRC treatment reduce the incidence rate among the population,but the micrometastasis of cancer may lead to ***,the challenge is to develop an alternative therapy to overcome this *** plays a vital role in cancer treatment and offers targeted chemotherapies directly and selectively to cancer cells,with enhanced therapeutic ***,nanotechnology elevates the chances of patient survival in comparison to traditional *** potential of nanoparticles includes that they may be used simultaneously for diagnosis and *** exciting properties of nanoparticles have enticed researchers worldwide to unveil their use in early CRC detection and as effective *** review discusses contemporary methods of CRC screening and therapies for CRC treatment,while the primary focus is on the theranostic approach of nanotechnology in CRC treatment and its *** addition,this review aims to provide knowledge on the advancement of nanotechnology in CRC and as a starting point for researchers to think about new therapeutic approaches using nanotechnology.

关键词： Nanoparticles Colorectal cancer Carbon nanotubes Dendrimers Quantum dots

Development and evaluation of lafutidine solid dispersion via hot melt extrusion:Investigating drug-polymer miscibility with advanced characterisation

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Asian Journal of Pharmaceutical Sciences 2014年第2期9卷 92-106页

作者： Ritesh Fule purnima Amin Department of Pharmaceutical Sciences and Technology Institute of Chemical TechnologyNathalal Parekh MargMatungaMumbai 400019MaharashtraIndia

In current study,immediate release solid dispersion(SD)formulation of antiulcer drug lafutidine(LAFT)was developed using hot melt extrusion(HME)*** Soluplusused as a primary solubilizing agent,with different concentrations of selected surfactants like PEG 400,Lutrol F127(LF127),Lutrol F68(LF68)were used to investigate their influence on formulations processing via *** amorphous glassy solid dispersion was found to be thermodynamically and physicochemically *** the contrary,traces of crystalline LAFT not observed in the extrudates according to differential scanning calorimetry(DSC),X-ray diffraction(XRD),scanning electron microscopy(SEM)and Raman *** micro spectrometry had the lowest detection limit of LAFT crystals compared with XRD and *** Force microscopy(AFM)studies revealed drugpolymer molecular miscibility and surface interaction at micro level.1HeCOSY NMR spectroscopy confirmed miscibility and interaction between LAFT and Soluplus,with chemical shift drifting and line *** simulation studies using computational modelling showed intermolecular interaction between *** rate and solubility of LAFT was enhanced remarkably in developed SD *** ratio of polymer and surfactants played crucial role in dissolution rate enhancement of LAFT *** obtained results suggested that developed LAFT has promising potential for oral delivery and might be an efficacious approach for enhancing the therapeutic potential of LAFT.

关键词： Lafutidine Solid dispersion Hot melt extrusion Dissolution rate Raman spectroscopy Atomic force microscopy

Reconstruction of Pathways Associated with Amino Acid Metabolism in Human Mitochondria

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Genomics, Proteomics & Bioinformatics 2007年第3期5卷 166-176页

作者： purnima Guda Chittibabu Guda Shankar Subramaniam Gen *NY* sis Center for Excellence in Cancer Genomics and Department of Epidemiology and Biostatistics State University of New York at AlbanyRensselaerNY 12144-3456USA San Diego Supercomputer Center University of California at San DiegoLa JollaCA 92093-0505USA Departments of BioengineeringChemistry and BiochemistryUniversity of California at San DiegoLa JollaCA 92093USA.

We have used a bioinformatics approach for the identification and reconstruction of metabolic pathways associated with amino acid metabolism in human mitochondria. Human mitochondrial proteins determined by experimental and computational methods have been superposed on the reference pathways from the KEGG database to identify mitochondrial pathways. Enzymes at the entry and exit points for each reconstructed pathway were identified, and mitochondrial solute carrier proteins were determined where applicable. Intermediate enzymes in the mitochondrial pathways were identified based on the annotations available from public databases, evidence in current literature, or our MITOPRED program, which predicts the mitochondrial localization of proteins. Through integration of the data derived from experimental, bibliographical, and computational sources, we reconstructed the amino acid metabolic pathways in human mitochondria, which could help better understand the mitochondrial metabolism and its role in human health.

关键词： mitochondria metabolic pathways amino acid metabolism human