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Dynamic Fracture Toughness of Armour grade Quenched and Tempered Steel Joints Fabricated Using Low Hydrogen Ferritic Fillers

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Journal of Iron and Steel Research(International) 2010年第5期17卷 51-56页

作者： g Magudeeswaran V Balasubramanian S Sathyanarayanan g Madhusudhan Reddy A Moitra S Venugopal g sasikala Department of Mechanical Engineering Pannaikkadu Veerammal Paramasivam College of Engineering andTechnology for Women Department of Manufacturing Engineering Annamalai University Materials Mechanics Section Indira Gandhi Center for Atomic Research Metal JoiningSection Defence Metallurgical Research Laboratory

The armour grade quenched and tempered steel joints fabricated using low hydrogen ferritic steel （LHF） filler exhibited superior joint efficiency owing to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions, fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness （K1d）. Hence, an attempt was made to study dynamic fracture toughness of the armour grade quenched and tempered steel and their welds fabricated using LHF consumables. The experimental results indicate that the K1d values of the joints fabricated by shielded metal arc welding （SMAW） are higher than those of the joints fabricated using flux cored arc welding （FCAW） process.

关键词： quenched steel tempered steel low hydrogen ferritic steel dynamic fracture toughness

Modelling Mobile-X Architecture for Offloading in Mobile Edge Computing

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Intelligent Automation & Soft Computing 2023年第4期36卷 617-632页

作者： g.Pandiyan E.sasikala Department of Data Science and Business System SRM Institute of Science and TechnologyChennaiIndia

Mobile Edge Computing(MEC)assists clouds to handle enormous tasks from mobile devices in close *** edge servers are not allocated efﬁciently according to the dynamic nature of the *** leads to processing delay,and the tasks are dropped due to time *** researchersﬁnd it difﬁcult and complex to determine the ofﬂoading decision because of uncertain load dynamic condition over the edge *** challenge relies on the ofﬂoad-ing decision on selection of edge nodes for ofﬂoading in a centralized *** study focuses on minimizing task-processing time while simultaneously increasing the success rate of service provided by edge ***,a task-ofﬂoading problem needs to be formulated based on the communication and *** ofﬂoading decision problem is solved by deep analysis on taskﬂow in the network and feedback from the devices on edge *** signiﬁcance of the model is improved with the modelling of Deep Mobile-X architecture and bi-directional Long Short Term Memory(b-LSTM).The simulation is done in the Edgecloudsim environment,and the outcomes show the signiﬁcance of the proposed *** processing time of the anticipated model is 6.6 *** following perfor-mance metrics,improved server utilization,the ratio of the dropped task,and number of ofﬂoading tasks are evaluated and compared with existing learning *** proposed model shows a better trade-off compared to existing approaches.

关键词： Mobile edge computing cloud ofﬂoading delay task drop reinforcement learning mobile-X architecture

Orthogonal frequency division multiplexing for improving the performance of terahertz channel

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红外与毫米波学报 2019年第3期38卷 263-268,284页

作者： M.Bharathi A.Amsaveni S.sasikala Kumaraguru College of Technology

Terahertz( THz) communication is considered to be one of the demanding technology for the upcoming 5g standards. The incredible demand for high rate through wireless channel necessitates the use of THz frequency for communication. The development of communication systems in this frequency band possess technical challenges as the characteristic of THz band is very different from the present wireless channel. However,the advancements in the development of transceiver and antenna systems are rapidly bringing the THz communication into reality. The high path loss in THz band limits the communication range of this channel. Even,for a distance of few meters( >5 m),the absorption coefficient is very high and hence the performance of the system is poor. Performance over this frequency channel can be enhanced by considering transmission windows over this band instead of the entire band. The transmission windows are the frequencies over which the absorption is relatively low. Though there is an improvement in the performance with this adaptive modulation scheme,but not sufficient for longer distance. Apart from path loss,the frequency selective nature of this high bandwidth channel is also a major reason for the poor performance of THz channel. Orthogonal Frequency Division Multiplexing( OFDM) is a promising solution to mitigate the effects of frequency selective nature of the wireless channel. OFDM has been exploited in this paper to improve the performance of terahertz channel. The results show that the Bit Error Rate( BER) of the terahertz channel is considerably improved with OFDM.

关键词： Terahertz communication Channel modeling LOS NLOS Performance BER OFDM.

Investigation on 1.07 μm laser emission in Nd^(3+)-doped sodium fluoroborate glasses

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Journal of Rare Earths 2012年第5期30卷 413-417页

作者： D.Umamaheswari B.C.Jamalaiah T.sasikala g.V.Lokeswara Reddy L.Rama Moorthy Department of Physics Sri Venkateswara UniversityTirupati517 502India Department of Physics Changwon National UniversityChangwon641 773Republic of Korea

Spectroscopic and fluorescence properties of Nd 3＋ ions in sodium fluoroborate（SFB） glasses were prepared and characterized through optical absorption,emission and decay *** energy level analysis was carried out using free-ion Hamiltonian *** oscillator strengths were determined by measuring the area encompassed by the absorption peaks recorded for 1.0 mol.% Nd 3＋-doped *** Judd-Ofelt parameters（2,4,6） were used to evaluate the laser characteristic parameters such as radiative transition probability（A R）,radiative decay time（τ R）,fluorescence branching ratio（β R） and stimulated emission cross-section（σ e） for the 4 F 3/2 metastable *** fluorescence spectra for different concentrations of Nd 3＋ ions were recorded by exciting the samples at 514.5 nm Ar ＋ ion laser.

关键词： sodium fluoroborate glasses rare earth spectroscopy Judd-Ofelt theory laser materials

Pancreatic stellate cell: Pandora's box for pancreatic disease biology

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World Journal of gastroenterology 2017年第3期23卷 382-405页

作者： Ratnakar R Bynigeri Aparna Jakkampudi Ramaiah Jangala Chivukula Subramanyam Mitnala sasikala g Venkat Rao D Nageshwar Reddy Rupjyoti Talukdar Institute of Basic Sciences Asian Healthcare FoundationHyderabad 500082India Department of Medical gastroenterology Asian Institute of GastroenterologyHyderabad 500082India Department of Surgical gastroenterology Asian Institute of GastroenterologyHyderabad 500082India

Pancreatic stellate cells(PSCs) were identified in the early 1980 s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis(CP) and pancreatic ductal adenocarcinoma(PDAC). Several pathways(e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and mi RNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

关键词： Pancreatic stellate cells Pancreatic fibrosis Pancreatic cancer stroma Physiological functions Pancreatic stellate cells-cancer-stromal interactions Therapeutic targets

Differentiation of Pancreatic Ductal Epithelial Cells into Insulin Like Cell Clusters in Chronic Pancreatitis

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Open Journal of Endocrine and Metabolic Diseases 2015年第12期5卷 177-183页

作者： Pondugala Pavan Kumar gaddipati Radhika g. Venkat Rao D. Nageshwar Reddy M. sasikala Asian Health Care Foundation Somajiguda Hyderabad India Asian Institute of gastroenterology Somajiguda Hyderabad India

Background/Aim: Islet regeneration in chronic pancreatitis (CP) is relevant for managing the associated loss of endocrine function. Because ductal epithelial cells were earlier demonstrated to differentiate into pancreatic endocrine mass, we evaluated their proliferation and differentiation in chronic pancreatitis. Methods: Pancreatic ducts were obtained from surgically resected pancreata of 12 patients with chronic pancreatitis and 15 control subjects. CK19 positive ductal cells were evaluated for their proliferating and differentiating abilities upon immunostaining with Ki 67 and hormone positivity for insulin and glucagon, apart from monitoring Pdx 1 expression. Results: In comparison to the controls, a greater number of proliferating pancreatic ductal epithelial cells (PDECs) were observed under conditions of CP. The increase in Pdx1 expressing PDECs (22%) and proliferating Pdx1 expressing PDECs (30%) was significant (P g insulin/glucagon in the exocrine ducts increased significantly in CP as compared to controls (P ?β?cell mass adjacent to the ducts increased by 28%.?Conclusion: Enhanced capability of PDECs to proliferate and differentiate into endocrine mass suggests that PDECs form a source of progenitors for cell based therapy in chronic pancreatitis.

关键词： Chronic Pancreatitis Ductal Epithelial Cells Islet Like Clusters Cell Differentiation

Dysregulated miRNA Associated with Transcription Factors of Insulin gene Expression in Chronic Pancreatitis

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Open Journal of Endocrine and Metabolic Diseases 2016年第10期6卷 205-227页

作者： K. Murali Manohar M. sasikala P. Pavan Kumar g. V. Rao D. Nageshwar Reddy Institute of Basic Science and Translational Research Asian Healthcare Foundation Hyderabad India Asian Institute of gastroenterology Somajiguda Hyderabad India

Background/Aim: MicroRNAs with regulatory functions in gene expression are implicated in different diseases. The present study investigated differentially expressed miRNAs that possibly influence transcription factors involved in insulin gene expression in Chronic Pancreatitis (CP) employing bioinformatics approaches. Methods: Pancreatic tissues were collected from CP patients undergoing partial pancreatectomy (n = 16) and controls (n = 15) undergoing resections for non-pancreatic malignancies. MiRNA profiles obtained using microarrays were validated by qRT-PCR. Target search involving miRWalk and TarBase as well as functional annotation employing KEgg (Kyoto encyclopedia of genes and genomes) and DAVID (Database for Annotation) databases were performed. Ingenuity pathway analysis (IPA) was used to construct networks relating miRNAs to their target genes. mRNA and proteins related to insulin gene transcription factors and hormones were evaluated by qRT-PCR and western blotting followed by confirmation upon immunofluorescent staining. Results: Microarray data revealed 10 up-regulated and 15 down-regulated miRNAs in CP as compared to controls (Log2 FC > 2). Bioinformatic analysis showed 8399 target genes and KEgg pathway analysis suggested a role for the dysregulated miRNAs in modulating cytokine signaling, fibrosis, JAK-STAT signaling and insulin synthesis. IPA analysis suggested a simplified network attributing dysregulated miRNAs to NFκB-dependent cytokine signaling. Further, associations could be noted between miRNA 200b with Maf A, 138-1 with Neuro D and 27b with FoxO1. Decreases in mRNA levels of Pdx1, Neuro D and increases of Maf A and FoxO1 transcription factors could be noted (P Conclusion: Our results identified dysregulation of miRNAs 138-1, 27b and 200b which were found to be associated with insulin gene transcription factors Neuro D, FoxO1 and Maf A respectively.

关键词： MicroRNAs Transcription Factors Networks β-Cell Dysfunction

Characterization of Islets from Chronic Calcific Pancreatitis Patients of Tropical Region with Distinct Phenotype

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Advances in Bioscience and Biotechnology 2016年第1期7卷 1-10页

作者： P. Pavan Kumar M. sasikala K. Mamatha g. V. Rao R. Pradeep R. Talukdar D. Nageshwar Reddy Asian Healthcare Foundation Hyderabad India Asian Institute of gastroenterology Hyderabad India

Background and Objective: Islet autotransplantation is performed to preserve endocrine function in patients undergoing pancreatic resections for painful chronic pancreatitis. We characterized islets isolated from chronic pancreatitis patients (CP) of tropical region. Patients and Methods: Pancreatic tissues were obtained from CP patients with and without diabetes undergoing pancreatic resections (n = 35) and brain-dead multi organ donors (n = 6;considered as controls). Islets isolated were assessed for yield, purity, viability and in vitro islet function (glucose stimulated insulin release, gSIR) as per standard protocols. Results: Islets from CP patients without diabetes were similar to controls in yield (control 4120 - 6100 IE/g, CP 3550 - 5660 IE/g), purity (control 78% ± 12%, CP 70% ± 8.2%) and viability (control 85% ± 8%, CP 81% ± 10%) and islets from CP patients with diabetes showed decreases in yield (3002 - 2300 IE/g), purity (61% ± 16%) and viability (62% ± 21%). Islets measuring 50 - 200 μ were similar in abundance in controls (94.74% ± 3.2%) and CP patients with and without diabetes, 86.31% ± 4.9%, 91.03% ± 3.8%. gSIR of islets from CP patients and controls were similar at 5.5 mM glucose (2.8 - 3.1 μU/ml). However, gSIR at 16.5 mM glucose was decreased in CP patients (control 18.5 ± 0.6, CP without diabetes 11.8 ± 0.3, CP with diabetes 4.3 ± 0.3 μU/ml). Conclusion: Our results demonstrate suitability of islets isolated from CP patients of tropical region for autotransplantation.

关键词： Islets Tropical Chronic Pancreatitis Islet Functions Transplantation

Autologous mobilized peripheral blood CD34^+ cell infusion in non-viral decompensated liver cirrhosis

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World Journal of gastroenterology 2015年第23期21卷 7264-7271页

作者： Mithun Sharma Padaki Nagaraja Rao Mitnala sasikala Mamata Reddy Kuncharam Chimpa Reddy Vardaraj gokak BPSS Raju Jagdeesh R Singh Piyal Nag D Nageshwar Reddy Department of gastroenterology and Hepatology Asian Institute of Gastroenterology Asian Healthcare Foundation Asian Healthcare Foundation Department of Interventional Radiology Asian Institute of Gastroenterology

AIM: To study the effect of mobilized peripheral blood autologous CD34 positive(CD34+) cell infusion in patients with non-viral decompensated ***: Cirrhotic patients of non-viral etiology were divided into 2 groups based on their willingness to be listed for deceased donor liver transplant(DDLT)(control, n = 23) or to receive autologous CD34+ cell infusion through the hepatic artery(study group, n= 22). Patients in the study group were admitted to hospital and received granulocyte colony stimulating factor injections 520 μg/d for 3 consecutive days to mobilize CD34+ cells from the bone marrow. On day 4,leukapheresis was done and CD34+ cells were isolated using CliniMAC magnetic cell sorter. The isolated CD34+ cells were infused into the hepatic artery under radiological guidance. The patients were discharged within 48 h. The control group received standard of care treatment for liver cirrhosis and were worked up for DDLT as per protocol of the institute. Both groups were followed up every week for 4 wk and then every month for 3 ***: In the control and the study group, the cause of cirrhosis was cryptogenic in 18(78.2%) and16(72.72%) and alcohol related in 5(21.7%) and6(27.27%), respectively. The mean day 3 cell count(cells/μL) was 27.00 ± 20.43 with a viability of 81.84± 11.99%. and purity of 80%-90%. Primary end point analysis revealed that at 4 wk, the mean serum albumin in the study group increased significantly(2.83± 0.36 vs 2.43 ± 0.42, P = 0.001) when compared with controls. This improvement in albumin was,however, not sustained at 3 mo. However, at the end of3 mo there was a statistically significant improvement in serum creatinine in the study group(0.96 ± 0.33 vs 1.42 ± 0.70, P = 0.01) which translated into a significant improvement in the Model for End-Stage Liver Disease score(15.75 ± 5.13 vs 19.94 ± 6.68,P = 0.04). On statistical analysis of secondary end points, the transplant free survival at the end of 1 mo and 3 mo did not show

关键词： CD34 cell infusion Stem cell Cirrhosis Model for end-stage liver disease Liver transplantation