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CURInG KInETICS AnD THERMAL STABILITY OF EPOXY BLEnDS COnTAInInG PHOSPHOROUS-OXIRAnE WITH AROMATIC AMIDE-AMInE AS CURInG AGEnTS

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Chinese Journal of Polymer Science 2012年第5期30卷 694-704页

作者： Geeta durga A.K.narula School of Basic and Applied Sciences Guru Gobind Singh Indraprastha University

This article describes the synthesis of a series of aromatic amide-amines and their potential use as epoxy hardeners. These amines were synthesized by the reaction of L-phenylalanine （PA） with diamines of different structures i.e. 1,4- phenylene diamine （PD）, 1,5-diamino naphthalene （n）, 4,4＇-（9-fluorenyllidene）-dianiline （F）, 4,4＇-diaminodiphenyl sulphide （DS） and 3,4＇-oxydianiline （O） in a stoichiometric ratio （I ：1）. Structural characterization of synthesized amide-amines was done with the help of elemental analysis and spectroscopic techniques viz. FT-IR, 1H-nMR and 13C-nMR. An epoxy blend was prepared by mixing tris（glycidyloxy） phosphine oxide （TGPO） with conventional epoxy i.e. diglycidyl ether of bisphenol-A （DGEBA） in an equivalent ratio of 2：3 to incorporate phosphorous into the main chain. The curing kinetics of the epoxy blend with synthesized aromatic amide-amines was investigated by non-isothermal DSC technique using multiple heating rate method （5, 10, 15 and 20 K/min.）. The activation energies were determined by fitting the experimental data into Kissinger and Ozawa kinetic models. The activation energies obtained through Ozawa method were slightly higher than those of Kissinger method but were comparable. However, both the energies were found to be dependent on the structure of amines. The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis （TGA） in nitrogen atmosphere. All the samples showed improved thermal stability in terms of char yield than using only amines as hardeners.

关键词： Phosphorylated epoxy Amide-Amines Curing kinetics Char yield Thermal stability.

Bismuth Modified Porous Silica Preparation,Characterization and Photocatalytic Activity Evaluation for Degradation of Isoproturon

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Journal of Materials Science & Technology 2013年第7期29卷 639-646页

作者： Anil Kumar Reddy Police Srinivas Basavaraju durga Kumari Valluri Subrahmanyam Machiraju Inorganic and Physical Chemistry Division Indian Institute of Chemical TechnologyHyderabad 500607India

Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Si05 species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectroscopy （XRD）, X-ray photoelectron spectroscopy （XPS）, UV-Vis diffuse reflectance spectroscopy （UV-Vis DRS）, scanning electron microscopy （SEM）, energy dispersive analysis of X-ray （EDAX）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and n2 adsorption/desorption techniques. EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi2SiO5, which is substantiated by XRD. The UV-Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica. FTIR spectra illustrate the formation of Bi-O-Si linkages in the porous silica framework. SEM and TEM show the spherical morphology, whereas n2 adsorption/desorption study confirms the porosity of the prepared materials. The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa TiO2.

关键词： Acrylic emulsion Emulsion polymerization technique Porous silica Bi2SiO5 Photocatalyfic degradation lsoproturon

Development and Validation of Stability Indicating HPLC Method for Simultaneous Estimation of Amoxicillin and Clavulanic Acid in Injection

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American Journal of Analytical Chemistry 2010年第3期1卷 95-101页

作者： durga Mallikarjuna Rao Tippa n. Singh 不详

A simple, fast, precise, accurate and rugged stability indicating high performance liquid chromatography (HPLC) method has been developed for simultaneous estimation of Amoxicillin and Clavulanic acid from injectable dosage form. The stability indicating capability of the method was proven by subjecting the drugs to stress conditions as per ICH recommended test conditions such as alkaline and acid hydrolysis, oxidation, photolysis, thermal degradation and resolution of the degradation products formed therein. The separation was obtained using a mobile phase composition at a ratio of 95:5 (v/v) of pH 5.0 buffer and methanol on Inertsil C18 column (250 × 4.0 mm, 4 μm) with UV detection at 220 nm at a flow rate of 1 ml/minute. The photodiode array detector was used for stress studies. The order of elution of peaks was Clavulanic acid followed by Amoxicillin. The linear calibration range was found to be 79.51 to 315.32 μg/ml for Amoxicillin and 17.82 to 67.90 μg/ml for Clavulanic acid. The Amoxicillin and Clavulanic acid were found to be stable in solution up to 24 hours. The method validation data showed excellent results for precision, linearity, specificity, limit of detection, limit of quantification and robustness. The present method can be successfully used for routine quality control and stability studies.

关键词： Amoxicillin Clavulanic Acid HPLC Stability Indicating

Synthesis of n-substituted-2-aminobenzothiazoles using nano copper oxide as a recyclable catalyst under ligand-free conditions in reusable PEG-400 medium

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Chinese Chemical Letters 2014年第5期25卷 732-736页

作者： Satish Gaddam Harshavardhan Reddy Kasireddy Karnakar Konkala Ramesh Katla nageswar Yadavalli Venkata durga CSIR-Medicinal Chemistry and Pharmacology Division Indian Institute of Chemical Technology

A simple and practical method for the synthesis of n-substituted-2-aminobenzothiazoles via a crosscoupling reaction of 2-iodo anilines with isothiocyanates is envisaged using nano copper oxide as a recyclable catalyst and Cs2CO3as a base in PEG-400,as a bio-degradable,reusable,inexpensive and nontoxic reaction medium,under ligand-free *** present tandem process underlines environmental acceptability to access a wide range of n-substituted-2-aminobenzothiazoles in good to excellent yields.

关键词： 2-Aminobenzothiazoles 2-Iodoanilines Isothiocyanates CuO nanoparticles Recyclability PEG-400

Penoscrotal defect:a functional,esthetic,and psychological challenge

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Plastic and Aesthetic Research 2016年第1期3卷 64-67页

作者： durga Karki Pankaj Kumar Patel Ravi Prakash narayan Department of Burns Plastic and Maxillofacial SurgerySafdarjung HospitalNew Delhi 110029India

Aim:Penoscrotal defects may be caused by a variety of *** of the penoscrotal region is required not only for aesthetic appearance but also for functional and psychological *** techniques have been described for penoscrotal reconstruction reflecting the challenge and complexity of the region *** suggests that no single method is satisfactory for all types and degrees of tissue *** prospective study was conducted in a tertiary care hospital in India,over a period of 5 ***:Eighteen patients with penoscrotal defects of varying etiology were included in the study and underwent different surgical *** of the patients ranged from 20 to 60 *** etiology of penoscrotal defect was Fournier’s gangrene in 12 cases,trauma in 4 cases,and burn in 2 *** patients with Fournier’s gangrene were initially treated by debridement,drainage,and *** penoscrotal defects were treated with local flap advancement with skin grafting(n=7),pedicled anterolateral thigh flap(n=4),gracilis muscle flap with split skin grafting(n=4),and medial thigh flap(n=3).Results:There was complete healing in 16 patients with minor complications in the form of partial skin graft loss(n=1)and wound dehiscence(n=1).Results were highly satisfactory in 6 patients,satisfactory in 8 patients,and not satisfactory in 4 *** at the donor site was limited and ***:The vast arsenal of options for penoscrotal defect coverage ranges from skin grafting to flaps,and every case needs a customized approach with regard to its feasibility,outcome,and complication *** should be the preferred choice over the skin grafts because of the superior functional and aesthetic results and better compliance.

关键词： Anterolateral thigh flap gracilis muscle flap penoscrotal defect

Bidirectional link between diabetes mellitus and coronavirus disease 2019 leading to cardiovascular disease:A narrative review

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World Journal of Diabetes 2021年第3期12卷 215-237页

作者： Vijay Viswanathan Anudeep Puvvula Ankush D Jamthikar Luca Saba Amer M Johri Vasilios Kotsis narendra n Khanna Surinder K Dhanjil Misha Majhail durga Prasanna Misra Vikas Agarwal George D Kitas Aditya M Sharma Raghu Kolluri Subbaram naidu Jasjit S Suri M Viswanathan Hospital for Diabetes M Viswanathan Diabetes Research CentreChennai 600013India Annu’s Hospitals for Skin and Diabetes Nellore 524101Andhra PradeshIndia Department of Electronics and Communications Visvesvaraya National Institute of TechnologyNagpur 440010MaharashtraIndia Department of Radiology University of CagliariMonserrato 09045CagliariItaly Department of Medicine Division of CardiologyQueen’s UniversityKingstonON K7L 3N6Canada 3rd Department of Internal Medicine Hypertension CenterPapageorgiou HospitalAristotle University of ThessalonikiThessaloniki 541-24Greece Department of Cardiology Indraprastha APOLLO HospitalsNew Delhi 110020India Stroke Diagnosis and Monitoring Division AtheroPoint™LLCCA 95661United States Stroke Diagnosis and Monitoring Division AtheroPoint™RosevilleCA 95661United States Department of Clinical Immunology and Rheumatology Sanjay Gandhi Postgraduate Institute of Medical SciencesLucknow 226014Uttar PradeshIndia Departments of Medicine Sanjay Gandhi Postgraduate Institute of Medical SciencesLucknow 226014Uttar PradeshIndia Academic Affairs Dudley Group NHS Foundation TrustDudley DY12HQUnited Kingdom Arthritis Research UK Epidemiology Unit Manchester UniversityManchester M139PLUnited Kingdom Division of Cardiovascular Medicine University of VirginiaCharlottesvilleVA 22908United States OhioHealth Heart and Vascular OhioOH 43082United States Electrical Engineering Department University of MinnesotaDuluthMN 55812United States

Coronavirus disease 2019(COVID-19)is a global pandemic where several comorbidities have been shown to have a significant effect on *** with diabetes mellitus(DM)have a higher mortality rate than non-DM patients if they get *** studies have indicated that patients with a history of diabetes can increase the risk of severe acute respiratory syndrome coronavirus 2 ***,patients without any history of diabetes can acquire newonset DM when infected with ***,there is a need to explore the bidirectional link between these two conditions,confirming the vicious loop between“DM/COVID-19”.This narrative review presents(1)the bidirectional association between the DM and COVID-19,(2)the manifestations of the DM/COVID-19 loop leading to cardiovascular disease,(3)an understanding of primary and secondary factors that influence mortality due to the DM/COVID-19 loop,(4)the role of vitamin-D in DM patients during COVID-19,and finally,(5)the monitoring tools for tracking atherosclerosis burden in DM patients during COVID-19 and“COVID-triggered DM”*** conclude that the bidirectional nature of DM/COVID-19 causes acceleration towards cardiovascular *** to this alarming condition,early monitoring of atherosclerotic burden is required in“Diabetes patients during COVID-19”or“new-onset Diabetes triggered by COVID-19 in non-Diabetes patients”.

关键词： COVID-19 Diabetes mellitus Bidirectional association Cardiovascular disease Atherosclerotic burden Imaging tools

A Model Study on Accelerated Consolidation of Coir Reinforced Lateritic Lithomarge Soil Blends with Vertical Sand Drains for Pavement Foundations

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Open Journal of Soil Science 2012年第3期2卷 320-332页

作者： George Varghese Hegde Ramakrishna A.G. nirmal Kumar L. durga Prashanth G. Santosh Department of Civil Engineering National Institute of Technology India

Sub-grade soils of lateritic origin encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. This work deals with accelerated consolidation of un-reinforced and coir-rein- forced lateritic lithomargic soil blends, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50 kg (0.0013 n/mm2) to 500 kg (0.013n/mm2) on soil specimens prepared in circular ferro-cement moulds. It was observed that at lower preloads up to 200kg, across the blends, the relative increase in consolidation (Rct) for randomly reinforced soil with vertical drains was sig-nificantly higher than that of un-reinforced soil without vertical drains, with an average value of 124.8%. Also, the Rct for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with an average value of 103.9%. In the case of higher preloads, the Rct values for randomly reinforced soil with vertical drains were moderate with an average value of 30.88%, while the same for un-reinforced soil with vertical drains was about 20.4%. The aspect-ratio of coir fibers used was 1:275.

关键词： Vertical Sand Drains Accelerated Consolidation Settlement Coir Reinforcement Laterite Shedi Lithomarge

Photocatalytic Degradation of Isoproturon Pesticide on C, n and S Doped TiO2

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Journal of Water Resource and Protection 2010年第3期2卷 235-244页

作者： Police Anil Kumar Reddy Pulagurla Venkata Laxma Reddy Vutukuri Maitrey Sharma Basavaraju Srinivas Valluri durga Kumari Machiraju Subrahmanyam 不详

TiO2 doped with C, n and S (TCnS photocatalyst) was prepared by hydrolysis process using titanium iso-propoxide and thiourea. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photo electron spectroscopy (XPS), BET surface area, FTIR and diffuse reflectance spectra (DRS). The results showed that the prepared catalysts are anatase type and nanosized par-ticles. The catalysts exhibited stronger absorption in the visible light region with a red shift in the adsorption edge. The photocatalytic activity of TCnS photocatalysts was evaluated by the photocatalytic degradation of isoproturon pesticide in aqueous solution. In the present study the maximum activity was achieved for TCnS5 catalyst at neutral pH with 1 g L-1 catalyst amount and at 1.14 x 10-4 M concentration of the pesticide solution. The TCnS photocatalysts showed higher phtocatalytic activity under solar light irradiation. This is attributed to the synergetic effects of red shift in the absorption edge, higher surface area and the inhibition of charge carrier recombination process.

关键词： Isoproturon Pesticide Degradation C n and S Doped TiO2 Visible Light Active Catalysts