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Metallurgical analysis of a failed maraging steel shear screw used in the band separation system of a satellite launch vehicle

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Defence Technology（防务技术） 2016年第5期12卷 380-387页

作者： s.V.s. Narayana MURTY sushant K. MANWATKAR E Ramesh NARAYANAN Material Characterization Division Materials and Metallurgy Group Vikram Sarabhai Space Centre Trivandrum 695 022 India

Maraging steels have excellent combination of strength and toughness and are extensively used for a variety of aerospace applications. In one such critical application, this steel was used to fabricate shear screws of a stage separation system in a satellite launch vehicle. During assembly preparations, one of the shear screws which connected the separation band and band end block has failed at the first thread. Microstructural analysis revealed that the crack originated from the root of the thread and propagated in an intergranular mode. The failure is attributed to combined effect of stress and corrosion leading to stress corrosion cracking.

关键词： M250 grade maraging steel shear screw separation system Mermen band stress corrosion cracking

structural,Wettability and Optical Investigation of Titanium Oxynitride Coatings:Effect of Various sputtering Parameters

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Journal of Materials science & Technology 2012年第6期28卷 512-523页

作者： sushant K Rawal Amit Kumar Chawla R.Jayaganthan Ramesh Chandra Centre of Nanotechnology Indian Institute of Technology RoorkeeRoorkee-247667India Nano science Laboratory Institute Instrumentation CentreIndian Institute of Technology RoorkeeRoorkee-247667India Department of Mechanical Engineering Charotar University of Science and TechnologyChanga 388421India Department of Physics University of Petroleum and Energy StudiesDehradun-48007India Department of Metallurgical and Materials Engineering Indian Institute of Technology RoorkeeRoorkee-247667India

The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering. The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO=N and TiN phases with increasing nitrogen flow rate and deposition time, but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO=Ny and TiN phases. The stress and strain calculated by sin2~ method are compressive, which decrease with increasing nitrogen flow rate from 55 to I00 sccm （standard cubic centimeter per minute） and increase with increasing deposition time from 80 to I40 min due to atomic penning effect and increasing thickness of the deposited films. The titanium oxynitride films have contact angle values above 90 deg., indicating that films are hydrophobic. The maximum contact angle of I09.1 deg. is observed at deposition time of 140 min. This water repellent property can add value to potential protective, wear and corrosion resistant application of titanium oxynitride films. The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm; it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital. But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.

关键词： Titanium oxynitride sputtering parameters Contact angle Optical properties

Clandestine nanoelectromechanical tags for identification and authentication

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Microsystems & Nanoengineering 2020年第1期6卷 87-94页

作者： sushant Rassay Mehrdad Ramezani sumaiya shomaji swarup Bhunia Roozbeh Tabrizian Electrical and Computer Engineering Department University of FloridaGainesvilleFL 32611USA

The realization of truly unclonable identification and authentication tags is the key factor in protecting the global economy from an ever-increasing number of counterfeit ***,we report on the demonstration of nanoscale tags that exploit the electromechanical spectral signature as a fingerprint that is characterized by inherent randomness in fabrication *** from their ultraminiaturized size and transparent constituents,these clandestine nanoelectromechanical tags provide substantial immunity to physical tampering and *** algorithms are developed for digital translation of the spectral signature into binary fingerprints.A large set of tags fabricated in the same batch is used to estimate the entropy of the corresponding fingerprints with high *** tags are also examined under repetitive measurements and temperature variations to verify the consistency of the *** experiments highlight the potential of clandestine nanoelectromechanical tags for the realization of secure identification and authentication methodologies applicable to a wide range of products and consumer goods.

关键词： realization signature transparent

Photon orbits and phase transition for Letelier Ads black holes immersed in perfect fluid dark matter

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Chinese Physics C 2024年第6期48卷 247-259页

作者： Ashima sood Md sabir Ali J.K.singh sushant G.Ghosh Department of Mathematics Netaji Subhas University of TechnologyNew Delhi-110078India Centre for Theoretical Physics Jamia Millia IslamiaNew Delhi 110025India Department of Physics Mahishadal Raj CollegePurba MedinipurWest Bengal721628India Institute of Theoretical Physics&Research Center of Gravitation Lanzhou UniversityLanzhou 730000China Key Laboratory of Quantum Theory and Applications of MoE Lanzhou UniversityLanzhou 730000China Lanzhou Center for Theoretical Physics&Key Laboratory of Theoretical Physics of Gansu Province Lanzhou UniversityLanzhou 730000China Astrophysics and Cosmology Research Unit School of MathematicsStatistics and Computer ScienceUniversity of KwaZulu-NatalPrivate Bag X54001Durban 4000South Africa

We obtain an exact solution for spherically symmetric Letelier Ads black holes immersed in perfect fluid dark matter(PFDM).Considering the cosmological constant as the positive pressure of the system and volume as its conjugate variable,we analyze the thermodynamics of our black holes in the extended phase *** to the background clouds of strings parameter(a)and the parameter endowed with PFDM(β),we analyze the Hawking temperature,entropy,and specific ***,we investigate the relationship between the photon sphere radius and phase transition for the Letelier Ads black holes immersed in *** the analysis,with a particular condition,non-monotonic behaviors are found between the photon sphere radius,impact parameter,PFDM parameter,temperature,and *** can regard the changes in both the photon sphere radius and impact parameter before and after phase transition as the order parameter;their critical exponents near the critical point are equal to the same value,1/2,similar to that in ordinary thermal *** indicates that a universal relation of gravity may exist near the critical point for a black hole thermodynamic system.

关键词： Ads black holes perfect fluid dark matter Letelier spacetime photon orbit extended phase space thermodynamics correlation of photon orbit and thermodynamics

Additively manufactured Ti–Ta–Cu alloys for the next-generation load-bearing implants

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International Journal of Extreme Manufacturing 2024年第1期6卷 353-374页

作者： Amit Bandyopadhyay Indranath Mitra sushant Ciliveri Jose D Avila William Dernell stuart B Goodman susmita Bose W.M.Keck Biomedical Materials Research Laboratory School of Mechanical and Materials EngineeringWashington State UniversityPullmanWA 99164United States of America Veterinary Clinical sciences College of Veterinary MedicineWashington State UniversityPullmanWA 99164United States of America Department of Orthopedic surgery Stanford University Medical CenterRedwood CityCA 94063United States of America

Bacterial colonization of orthopedic implants is one of the leading causes of failure and clinical complexities for load-bearing metallic implants. Topical or systemic administration of antibiotics may not offer the most efficient defense against colonization, especially in the case of secondary infection, leading to surgical removal of implants and in some cases even limbs. In this study, laser powder bed fusion was implemented to fabricate Ti3Al2V alloy by a 1:1 weight mixture of CpTi and Ti6Al4V powders. Ti-Tantalum(Ta)–Copper(Cu) alloys were further analyzed by the addition of Ta and Cu into the Ti3Al2V custom alloy. The biological,mechanical, and tribo-biocorrosion properties of Ti3Al2V alloy were evaluated. A 10 wt.% Ta(10Ta) and 3 wt.% Cu(3Cu) were added to the Ti3Al2V alloy to enhance biocompatibility and impart inherent bacterial resistance. Additively manufactured implants were investigated for resistance against Pseudomonas aeruginosa and staphylococcus aureus strains of bacteria for up to 48 h. A 3 wt.% Cu addition to Ti3Al2V displayed improved antibacterial efficacy, i.e.78%–86% with respect to CpTi. Mechanical properties for Ti3Al2V–10Ta–3Cu alloy were evaluated, demonstrating excellent fatigue resistance, exceptional shear strength, and improved tribological and tribo-biocorrosion characteristics when compared to Ti6Al4V. In vivo studies using a rat distal femur model revealed improved early-stage osseointegration for alloys with10 wt.% Ta addition compared to CpTi and Ti6Al4V. The 3 wt.% Cu-added compositions displayed biocompatibility and no adverse infammatory response in vivo. Our results establish the Ti3Al2V–10Ta–3Cu alloy’s synergistic effect on improving both in vivo biocompatibility and microbial resistance for the next generation of load-bearing metallic implants.

关键词： Ti6Al4V load-bearing implants additive manufacturing 3D printing antibacterial performance

Computed tomography-based score model/nomogram for predicting technical and midterm outcomes in transjugular intrahepatic portosystemic shunt treatment for symptomatic portal cavernoma

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World Journal of Clinical Cases 2020年第5期8卷 887-899页

作者： Xiang-Ke Niu sushant Kumar Das Hong-Lin Wu Yong Chen Department of Radiology Affiliated Hospital of Chengdu UniversityChengdu 610081Sichuan ProvinceChina Department of Radiology Affiliated Hospital of North Sichuan Medical CollegeNanchong 637000Sichuan ProvinceChina Department of Interventional Radiology Nanfang HospitalSouthern Medical UniversityGuangzhou 510515Guangdong ProvinceChina

BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPs)may be technically difficult in patients with cavernous transformation of the portal vein(CTPV).Computed tomography(CT)is widely used for assessing the situation of the portal vein and its tributaries before TIPs,and an ultrasound-based Yerdel grading system has been developed,which is deemed useful for liver ***,we hypothesized that a CT-based CTPV scoring system could be useful for predicting technical and midterm outcomes in TIPs treatment for symptomatic portal *** To investigate the clinical significance of a CT-based score model/nomogram for predicting technical success and midterm outcome in TIPs treatment for symptomatic *** Patients with symptomatic CTPV who had undergone TIPs from January 2010 to June 2017 were retrospectively *** CTPV was graded with a score of 1-4 based on contrast-CT imaging findings of the diseased *** measures were technical success rate,stent patency rate,and midterm ***’s kappa statistic,the Kaplan-Meier and log-rank tests,and uni-and multivariable analyses were performed.A nomogram was constructed and verified by calibration and decision curve *** A total of 76 patients(45 men and 31 women;mean age,52.3±14.7 years)were enrolled in the *** inter-reader agreement(κ)of the CTPV score was *** was successfully placed in 78%of patients(59/76).The independent predictor of technical success was CTPV score(odds ratio[OR]=5.56,95%confidence interval[CI]:3.55-9.67,P=0.002).The independent predictors of primary TIPs patency were CTPV score and splenectomy(OR=9.22,95%CI:4.78-13.45,P=0.009;OR=4.67,95%CI:2.59-7.44,P=0.017).The survival rates differed significantly between the TIPs success and failure *** clinical nomogram was made up of patient age,model for end-stage liver disease score,and CTPV *** calibration curves and decision curve analysis verified the usefulness of the

关键词： Portosystemic shunt Transjugular intrahepatic Liver cirrhosis Portal hypertension Oesophageal and gastric varices Bleeding shunt dysfunction

Biochemical composition of the alligator pipefish, syngnathoides biaculeatus (Bloch, 1785)

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Chinese Journal of Oceanology and Limnology 2017年第6期35卷 1501-1510页

作者： sANAYE sushant Vilas PAWAR Ashwini pandurang RIVONKER Chandrasheker Umanath sREEPADA Rayadurga Anantha ANsARI Zakir Ali RAM Anirudh Aquaculture Laboratory CSIR-National Institute of Oceanography Goa-403004 India Department of Marine sciences Goa University Taleigao Plateau Goa-403206 India CsIR- National Institute of Oceanography Regional Centre Mumbai India

Considering the economic importance in traditional Chinese medicine(TCM) and lack of baseline information, we evaluated the proximate composition, fatty acid and amino acid profiles, trace element content and C:N ratio in the alligator pipefish, syngnathoides biaculeatus. Amongst proximate principals, a crude protein formed the major biochemical component((58.9±2.2)% dry weight). Mean percent concentrations(dry weight) of other components such as a total lipid(TL), ash and nitrogen-free extract measured were,(1.8±0.2)%,(19.2±2.2)% and(20.1±0.45)%, respectively. The fatty acid profile revealed the presence of 27 saturated fatty acids(sFA) with 13 straight-chained and 14 branched-chained, 28 unsaturated fatty acids(UFA) with 14 monounsaturated and 14 polyunsaturated and nine other minor fatty acids. Mean percent contributions of total sFAs and UFAs to TL were found to be(55.41±0.24)% and(44.05±0.25)%, respectively. Altogether, 16 dif ferent amino acids with an equal number of essential(EAA) and non-essential(NAA) ones were identified. Percent contributions by EAA and NAA to the total amino acid content were 38.11% and 61.89%, respectively. Trace metal concentrations in s. biaculeatus were generally low and their distribution followed the order, Mg>Fe>Zn>Mn>Cu>Cr>Ni>Hg>Co. The C:N ratio was(4.37±0.04)%. The profile of major biochemical constituents in alligator pipefish, s. biaculeatus revealed its potential use in TCM as well as a nutritional diet for human consumption. The results of the study would also form the basis for formulation and optimization of diets for the culture of s. biaculeatus.

关键词： alligator pipefish syngnathoides biaculeatus proximate composition fatty acids amino acids trace elements

Meta-analysis of Quantitative Diffusion-weighted MR Imaging in Differentiating Benign and Malignant Pancreatic Masses

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Journal of Huazhong University of science and Technology(Medical sciences) 2014年第6期34卷 950-956页

作者：牛翔科 Anup Bhetuwal sushant Das 肖应权孙凤曾利川杨汉丰 Department of Radiology Affiliated Hospital of Chengdu University sichuan Key Laboratory of Medical Imaging and Department of Radiology Affiliated Hospital of North Sichuan Medical College

There have been numerous studies done to explore the diagnostic performance of quanti- tative diffusion-weighted （DW） MR imaging to differentiate between benign and malignant pancre- atic masses. However, the results have been inconsistent. We performed a meta-analysis to investigate whether DW-MR imaging can differentiate between these two diseases. Databases including MEDLINE, EMBAsE and Cochrane Library were utilized to find relevant articles published between January 2001 and January 2014. A stata version 12.0 and a Meta-Disc version 1.4 were used to de- scribe primary results. Twelve studies with 594 patients, which fulfilled the inclusion criteria, were enrolled for the analysis. The pooled sensitivity and specificity of DW imaging was 0.91 （95% CI： 0.84, 0.95） and 0.86 （95% CI： 0.76, 0.93） respectively. The area under the curve of the summary re- ceiver operating characteristic was 0.95 （95% CI： 0.93, 0.96）. The results indicated that DW imaging might be a valuable tool for differentiating benign and malignant pancreatic masses.

关键词： apparent diffusion coefficient diffusion-weighted imaging magnetic resonance imaging meta-analysis pancreatic tumor pancreatic adenocarcinoma

Effect of micro arc oxidation treatment on localized corrosion behaviour of AA7075 aluminum alloy in 3.5% NaCl solution

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Transactions of Nonferrous Metals society of China 2012年第3期22卷 700-710页

作者： A.VENUGOPAL Rajiv PANDA sushant MANWATKAR K.sREEKUMAR L.RAMA KRIsHNA G.sUNDARARAJAN Material Characterization Division Materials and Metallurgy GroupVikram Sarabhai Space CentreThiruvananthapuram-695022India International Advanced Research Centre for Powder Metallurgy and New Materials Hyderabad-500005India

Alumina coating was formed on AA7075 aluminum alloy by micro arc oxidation（MAO） method and its corrosion and stress corrosion cracking（sCC） behaviors were examined in 3.5%（mass fraction） NaCl *** impedance spectroscopy（EIs） was used to evaluate the degradation of the coating as a function of immersion time and was modeled with appropriate equivalent *** load stress corrosion cracking（sCC） results followed by post-test metallographic observations demonstrated the usefulness of MAO coating to avoid the premature failure of the alloy due to severe localized corrosion initiated by Cu-and Fe-rich intermetallic phases.

关键词： aluminum alloy micro arc oxidation impedance spectroscopy stress corrosion