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Ballistic behavior of boron carbide reinforced AA7075 aluminium alloy using friction stir processing-An experimental study and analytical approach

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Defence Technology（防务技术） 2016年第1期12卷 25-31页

作者： I.sudhakar G.MADHUSUDHAN REDDY K.SRINIVASA rao department of mechanical engineering mvgrceVizianagaramIndia defence metallurgical research laboratory HyderabadIndia department of metallurgical engineering andhra universityVisakhapatnamIndia

High strength-to-weight ratio of non-ferrous alloys, such as aluminium, magnesium and titanium alloys, are considered to be possible replacement of widely accepted steels in transportation and automobile sectors. Among these alloys, magnesium is self explosive and titanium is costlier, and aluminium is most likely to replace steels. Application of aluminium or its alloys is also thought of as an appropriate replacement in defence field, especially to enhance the easiness in mobility of combat vehicles while maintaining the same standard as that of conventional armour grade steels. Hence most of the investigations have been confined to aluminium or its alloys as base material and open an era of developing the newer composite materials to address the major limitation, i.e. tribological properties. The surface composites can be fabricated by incorporating the ceramic carbides like silicon carbide, carbides of transition metals and oxides of aluminium using surface modification techniques, such as high energy laser melt treatment, high energy electron beam irradiation and thermal spray process which are based on fusion route. These techniques yield the fusion related problems, such as interfacial reaction, pin holes, shrinkage cavities or voids and other casting related defects, and pave the way to need of an efficient technique which must be based on solid state. Recently developed friction stir processing technique was used in the present investigation for surface modification of AA7075 aluminum alloy, which is an alternative to steels. In the present investigation, 160 μm sized boron carbide powder was procured and was reduced to 60 μm and 30 μm using high energy ball mill. Subsequently these powders were used to fabricate the surface composites using friction stir *** performance testing as per the military standard(JIS.0108.01) was carried out. In the present work, an analytical method of predicting the ballistic behavior of surface composites was

关键词： AA7075 aluminium alloy Friction stir processing(FSP) Surface metal matrix composite(SMMC) Boron carbide(B4C) Ballistic performance Target

Enhancement of wear and ballistic resistance of armour grade AA7075 aluminium alloy using friction stir processing

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Defence Technology（防务技术） 2015年第1期11卷 10-17页

作者： I.sudhakar V.MADHU G.MADHUSUDHAN REDDY K.SRINIVASA rao Department of Mechanical Engineering MVGRCE Vizianagaram India Defence Metallurgical Research Laboratory Hyderabad India Department of Metallurgical Engineering Andhra University Visakhapatnam India

Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.

关键词： Armour grade aluminium alloy Friction stir processing Boron carbide Molybdenum disulphide Wear Ballistic resistance

Evaluation of Frontal Sinus Index in Establishing Sex Dimorphism Using Three-Dimensional Cone Beam Computed Tomography in Northern Saudi Arabian Population

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Journal of Forensic Science and Medicine 2022年第1期8卷 1-5页

作者： Krishna A.rao Radhika Doppalapudi Naif Tami Al-Shammari Santosh Patil sudhakar Vundavalli Mohammad Khursheed Alam Department of Preventive Dentistry College of DentistryJouf UniversitySakakaKingdom of Saudi Arabia Department of Oral Medicine and Radiology College of DentistryJouf UniversitySakakaKingdom of Saudi Arabia

Purpose:Identification of sex of unknown people becomes important in situations of mass *** studies have shown that morphological characteristic of frontal sinus is distinctive to particular individual and hence,literature suggests that it can be used in establishing identification of a ***,few researches have concluded that,its use in detennining sexual dimorphism is ***:This study aimed to evaluate frontal sinus index using cone beam computed tomography(CBCT)and differentiate sex dimorphism based on the index *** and Methods:A retrospective cross-sectional study was undertaken using three-dimensional-CBCT *** simple random sampling method,150 scans were selected,out of which 74 were of male and 76 were of female within the age group of20-64 *** frontal sinus width and the height were measured,and the ratio was taken as frontal sinus *** index was correlated to the differentiation of *** were analyzed using SPSS,and sex dimorphism was assessed using discriminant function ***:The mean height of the frontal sinus in both males and females was 30.12±7.6 mm and 30.14±7.8 mm,*** mean width of frontal sinus in males(13.39±3.6 mm)was slightly more than that of females(12.06±3 mm).Conclusion:The parameter frontal sinus index measured using CBCT was found to be a contributing factor in sex determination in forensic identification within the sample population.

关键词： Discriminant function analysis forensic anthropology frontal sinus index sex dimorphism three-dimensional cone beam computed tomography

Cardiac Myxoma: 10 Years Study of Presentations, Resection and Outcome

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World Journal of Cardiovascular Surgery 2021年第10期11卷 83-94页

作者： Vinod Bhan Sri Satyavathi Kanchumarti sudhakar rao Velam Vanajakshamma Cardiovascular Thoracic Surgery Department Sri Venkateswara Institute of Medical Sciences Tirupati India Cardiology Department Sri Venkateswara Institute of Medical Sciences Tirupati India

Background: Cardiac myxoma is a very rare heart tumor which presents as life threatening mass in cardiac chamber. The tumor may present with vague symptoms which can lead to delay in diagnosis. Methods: 22 patients underwent complete excision of intracardiac myxoma between January 2011 and December 2020. Majority of the patients were females (60%) with mean age of 48.9 years who presented with symptoms of dyspnea on exertion. 3 patients had significant complications due to myxoma. 2 presenting with tumor embolism and limb ischemia while 1 patient presented with pulmonary edema. All patients were diagnosed by echocardiography which helped in evaluation of size and extent of tumor. Majority of patients underwent trans-septal biatrial approach for tumor excision. Results: 95% of patients survived the operation. The mean tumor size excised was 5.0 ±

关键词： Cardiac Myxoma Dyspnea Trans-Septal Approach

Comparison of Alkaline Treatment of Lead Contaminated Wastewater Using Lime and Sodium Hydroxide

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Journal of Water Resource and Protection 2010年第3期2卷 282-290页

作者： sudhakar M. rao G. C. Raju 不详

A lead-acid storage battery manufacturing industry in India produces several thousand liters of lead con-taminated acidic wastewater on a daily basis and uses hydrated lime to render the lead-contaminated acidic wastewater alkaline (pH = 8.0). Alkaline treatment of the acidic wastewater with lime though a cost-effective method, generates copious amount of lead-contaminated gypsum sludge. Other alkali agents such as sodium hydroxide, sodium carbonate and dolomite are also used for alkali treatment of the acid wastewaters. The present paper compares the relative efficiency of hydrated lime and 0.05 M to 1 M NaOH solutions with re-spect to 1) amounts of sludge produced, 2) immobilization of the soluble lead in the acidic wastewater (AWW) and 3) increase in TDS (total dissolved solids) levels upon treatment of AWW with NaOH solutions and lime. The study also performs equilibrium speciation upon alkaline treatment of AWW with lime and NaOH (sodium hydroxide) solutions using the Visual MINTEQ program to understand the chemical reac-tions occurring during treatment process.

关键词： Acid Alkali Agents Alkaline Treatment Battery Lead Speciation TDS

Influence of optical filtering on transmission capacity in single mode fiber communications

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Frontiers of Optoelectronics 2015年第4期8卷 424-430页

作者： M. Venkata sudhakar Y. Mallikarjuna REDDY B. Prabhakara rao Department of Electronics and Communication Engineering Jawaharlal Nehru Technological (JNT) University Kakinada AP India Department of Electronics and Communication Engineering Vasireddy Venkatadri Institute of Technology Guntur AP India

This paper presents the design and analysis of optical filters that are placed at the output of directly modulated vertical cavity surface emitting laser （VCSEL） in the process of inexpensive transmitter＇s implementation for upcoming generation optical access network. Generation of non return to zero （NRZ） optical signal from the transmitter for 110 km error-free single mode fiber （SMF） transmission at 10 Gb/s with bit error rate （BER） of 10-30 in the absence of the external modulator and encoder was proposed. Effects of super-Gaussian and Butterworth optical filters at VCSEL output were demonstrated to maximize performance of SMF optical systems without need of any dispersion compensation technique.

关键词： single mode fiber (SMF) optical filter,dispersion data rate

Comparison of Binding Parameter Constants between Sevelamer HCl Tablets and Renagel Tablets by a Validated Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) Method

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American Journal of Analytical Chemistry 2012年第12期3卷 820-827页

作者： Venkata Vivekanand Vallapragada Gopichand Inti Ajay Kanyadhara sudhakar rao Vidiyala Sreeramulu Jadi Department of Chemistry Sri Krishna Devaraya University Anantapur India Invagen Pharmaceutical Inc Hauppauge USA

Sevelamer Hydrochloride is a crossolinked polymeric amine;it is the active ingredient in Renagel Tablets. Sevelamer Hydrochloride is indicated for the control of hyperphosphatamiea in patients with end-stage renal disease. The binding parameter constants of Sevelamer Hydrochloride were determined using the Langmuir approximation for the dosage form at pH 4.0 and 7.0 by Inductively Coupled Plasma-Optical Emission Spectrometry. An ICP-OES method has been developed to estimate free phosphate in In-Vitro phosphate binding study of Sevelamer HCl Tablets. The method is selective and capable of detecting phosphate in the presence of placebo matrix. The method has been validated with a lower limit of quantitation of 0.2 mM for Phosphate. A linear response function was established for the range of concentrations 0.2 - 25.0 mM (r > 0.99) for Phosphate. The intra and inter day precision values for Phosphate met the acceptance as per Food and Drug Administrations guidelines. Phosphate was stable in the set of stability studies viz. bench-top and autosampler. The developed method was applied to in-vitro phosphate binding studies of Sevelamer HCl Tablets.

关键词： Binding Parameter Constants ICP-OES In-Vitro Phosphate Binding Study Langmuir Approximation Renagel Tablets Quantitation

Comparison of Binding Parameter Constants between Sevelamer Carbonate Tablets and Renvela Tablets by a Validated Ion Chromatography Method

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American Journal of Analytical Chemistry 2013年第5期4卷 213-220页

作者： Venkata Vivekanand Vallapragada Gopichand Inti Sreenivas Reddy Geevanagari sudhakar rao Vidiyala Sreeramulu Jadi Department of Chemistry Sri Krishna Devaraya University Anantapur India Invagen Pharmaceutical Inc. Hauppauge USA

Sevelamer Carbonate is a crossolinked polymeric amine, it is the active ingredient in Renvela Tablets. Sevelamer Carbonate is indicated for the control of hyperphosphatamiea in patients with end-stage renal disease. The binding parameter constants of Sevelamer Carbonate were determined using the Langmuir approximation for the dosage form at pH 4.0 and 7.0 by Ion Chromatography. An Ion Chromatogrpahy method has been developed to estimate free phosphate in in-vitro phosphate binding study of Sevelamer Carbonate Tablets. The method is selective and capable of detecting phosphate in the presence of placebo matrix. The method has been validated with a lower limit of quantitation of 0.2 mM for Phosphate. A linear response function was established in the range of concentrations 0.2 - 30.0 mM (r > 0.99) for Phosphate. The intra and inter day precision values for Phosphate met the acceptance as per Food and Drug Administrations guidelines. Phosphate was stable in the set of stability studies viz. bench-top and autosampler. The developed method was applied to in-vitro phosphate binding studies of Sevelamer Carbonate Tablets.

关键词： Binding Parameter Constants Ion Chromatography In-Vitro Phosphate Binding Study Langmuir Approximation

New Stability Indicating Method for Quantification of Impurities in Amlodipine and Benazepril Capsules by Validated HPLC

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American Journal of Analytical Chemistry 2013年第12期4卷 715-724页

作者： Rama Joga Venkata Eranki Gopichand Inti Venkatasubramanian Jayaraman Raghuram Pannala sudhakar rao Vidiyala Jadi Sree Ramulu Department of Chemistry Sri Krishnadevaraya University Anantapur India Quality & Analytical Development Department InvaGen Pharmaceuticals Inc. Hauppauge USA Quality & Analytical Development Department InvaGen Pharmaceuticals Inc. Hauppauge USA Department of Chemistry Sri Krishnadevaraya University Anantapur India Quality Assurance Department ScieGen Pharmaceuticals Inc. Hauppauge USA

A stability indicating LC method was developed for the simultaneous determination of Amlodipine and Benazepril capsules in pharmaceutical dosage form. Efficient chromatographic separation was achieved on Symmetry C18 stationary phase with simple combination of amobile phase containing 750 mL of DI Water, 250 mL of Acetonitrile and 2 mL of Octylamine into suitable container with adjusted pH to 2.50 ± 0.05 with the aid of Ortho phosphoric acid delivered in an isocratic mode and quantification was carried out using UV detection at 240 nm at a flow rate of 1.0 mL·min-1 with an injection volume of 20 μl and ambient column temperature. This method is capable to detect both the drug components of Amlodipine and Benazepril in presence of their degradation products (Amlodipine Imp-A and Benazepril Impurity-C) with a detection level of 0.05%. Amlodipine/Benazepril in their combination drug product were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the samples were analysed. Peak homogeneity data of Amlodipine and Benazeprilis were obtained using PDA detector, in the stressed sample chromatograms, demonstrating the specificity. The method shows excellent linearity over a range of 0.05%-2.0% for Amlodipine, Amlodipine Impurity-A and 0.05%-5.0% for Benazepril and Benazepril Impurity-C. The correlation coefficient for Amlodipine and Benazepril is 1. The relative standard deviation was always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination and the stability study of Amlodipine and Benazepril in pharmaceutical preparations. The developed HPLC method was validated with respect to linearity & range, accuracy, precision and robustness.

关键词： Column Liquid Chromatography Method Validation Stability Indicating Study Amlodipine and Benazepril