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Development of mg based biomaterial with improved mechanical and degradation properties using powder metallurgy

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Journal of magnesium and Alloys 2020年第3期8卷 883-898页

作者： Ajit Kumar Pulak m.Pandey Department of mechanical Engineering Indian Institute of TechnologyDelhi110016India

in the present work,biocompatible materials such as niobium(Nb),zinc(Zn)and calcium(Ca)have been blended with magnesium(mg)to develop a novel biomaterial(Bm)with improved mechanical and corrosion resistant *** metallurgy(Pm)technique was used to fabricate mg based *** powder of all aforementioned materials were mixed homogenously in specific quantities to create a uniform composite *** order to analyse the influence of process parameters on the mechanical properties of the fabricated part,experiments were performed considering central composite design(CCD).The effect of powder metallurgical parameters namely percentage Nb,compaction pressure,heating rate,sintering temperature and soaking time on the ultimate compressive strength(UCS)and sintered density was studied in the present *** was found that the UCS and sintered density increased with increase in compaction pressure,heating rate and sintering *** results also revealed that the increase in soaking time and percentage Nb,increased sintered density and UCS to a certain *** increase in these two parameters,sintered density and UCS *** electron microscopy(SEm)images of the fabricated samples showed reduction in porosity with the increase in heating ***,X-ray diffraction(XRD)results revealed that no other phase or impurities were found during sintering of mg based *** optimum process parameters were obtained to develop mg based Bm for maximum UCS and sintered ***,the mg based Bm samples fabricated at optimum process parameters were used for corrosion testing in simulated body fluid(SBF)solution at a temperature of 37±0.5℃.The mg based Bm yielded improved mechanical properties with reduced corrosion rates as compared to pure mg.

关键词： Biomaterials Powder metallurgy magnesium Corrosion metal matrix composite

Development of a Long-Term Operational Optimization model for a Building Energy System Supplied by a Geothermal Field

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Journal of Thermal Science 2022年第5期31卷 1293-1301页

作者： KÜmPEL Alexander STOFFEL Phillip mÜLLER Dirk RWTH Aachen University E.ON Energy Research CenterInstitute for Energy Efficient Buildings and Indoor ClimateAachen 52074Germany

in order to reduce energy consumption and CO_(2) emissions in the building sector, more and more renewable energy sources are integrated into energy systems. Especially geothermal fields combined with heat pumps are able to supply buildings with heat and cold at low carbon emissions. However, using geothermal fields as heat and cold source influences the ground temperature. Consequently, the ground temperature can change dramatically over a building’s lifetime, leading to less efficient operation of the energy system. Therefore, a sustainable operation is required to ensure the long-term efficiency of geothermal fields. in this paper, we develop an optimization model to derive operating strategies for an efficient long-term operation of a building energy system coupled to a geothermal field. The investigated energy system is the main building of the *** Energy Research Center in Aachen, Germany, which includes a heat pump, two boilers, a combined heat, and power unit, a glycol cooler, and a geothermal field with 41 probes. For each component, we develop energy-based sub-models, which are connected to form the overall system. The geothermal field is modeled by using a g-functions approach as well as a simplified resistance-capacitance approach. To achieve short computing times and realize an optimization horizon of several years, the optimization problem is formulated as mixed-integer linear programming(miLP). The developed model is optimized regarding two different objectives: the minimization of energy costs and the minimization of long-term temperature changes in the ground. Conclusions for an efficient and sustainable operation of the field, especially for the cooling supply, can be derived from the optimization results. it is shown that a state of equilibrium should be aimed to achieve an energy-efficient operation, in which the temperature of the field is close to the initial ground temperature.

关键词： geothermal energy building energy systems operational optimization long-term operation

Sociodemographic and clinical characteristics of SARS-CoV-2 infected population during the second and third epidemiological waves in Sri Lanka

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Asian Pacific Journal of Tropical medicine 2023年第1期16卷 33-38页

作者： Hewa Babarandage Chathurika Harshani Ruvini Tharuka Wijewickrama Gayan Wimalarathne Chrishan Jude S Jayamaha Janaki i Abeynayake medical Research institute Colombo-08Sri Lanka

Objective:To analyze data on socio-demographic and clinical characteristics of SARS-CoV-2 infected population whose samples were received from medical Research institute,Sri ***:Laboratory based retrospective study was done on patient samples which were tested positive for SARS-CoV-2 by National Reference Virology Laboratory at the medical Research institute,Sri Lanka,from November,2020 to November,*** on sociodemographic characteristics and clinical presentation of 13126 patients were ***:The mean age of the study population was(36.0±7.2)years and the majority were men(64.0%).The highest number of positive cases were found in the 21-30 years-of-age *** distinct peaks were noted in the incidence of SARS-CoV-2 positive *** addition,42.5%of the positive samples tested positive(42.5%)were from medical Officer of Health collection ***,60.6%(7951)of the infected subjects were asymptomatic whereas the remaining were *** highest percentage of symptomatic patients were observed in the 91-100 years-of-age group while the highest asymptomatic subjects were found in the 31-40 years-of-age *** percentage of asymptomatic children(65.3%)was significantly(Pigher than that of adults(43.4%).Conclusions:The findings of this study aid decision makers to focus on the vulnerable groups,and geographic and temporal distribution of patients in the public health strategies that aim at preventing the spread of the disease and reducinig its mortalities.

关键词： COViD-19 SARS-CoV-2 Socio-demographic Clinical

Conservative management of Pulmonary Artery Dissection

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Surgical Science 2015年第7期6卷 311-316页

作者： S. Togo m. A. Ouattara i. Sankaré S. Yéna N. Diani A. m. Camara Thoracic Surgery Department Hospital of Mali Bamako Mali Department of Reanimation (intensive Care Unit) Hospital of Mali Bamako Mali Department of Radiology Hospital of Mali Bamako Mali

The pulmonary artery dissection (PAD) is a rare and life-threatening event, usually secondary to a chronic pulmonary artery hypertension. We report the case of pulmonary artery dissection undergoing medical treatment by conservative management, discovered by performing a computed tomography (CT), and describe the clinical and therapeutic characteristics with the literature review.

关键词： Pulmonary Artery Dissection Computed Tomography Conservative management

Effect of antigens on colony forming efficiency of stromal clonogenic cells and expression of cytokine genes in primary cultures of bone marrow and spleen of mice

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Advances in Bioscience and Biotechnology 2011年第5期2卷 315-319页

作者： U.F. Gorskaya T.A. Danilova m.V. mezentseva i.m. Shapoval V.G. Nesterenko 不详

Presence of microbial cells preparation (HCL – extract of group A streptococcus) in primary cell cultures of bone marrow (BmCC) and spleen (SCC) of CBA mice induced the expression mRNA of proinflammatory cytokines genes: iL-2, iL-6 and iL-8 in BmCC;in SCC cultures mRNA iL-1 β and iL-6 appeared and mRNA iL-4 disappeared. injection of S. typhimurium antigen complex to mice CBA increased 5 times colony forming efficiency (CFE) and, respectively, content of stromal precursor cells (CFU-F) in femur bone marrow and 9 times in spleen of these animals with maximum at the first day. in both primary BmCC and SCC from immunized animals expression of proinflammatory cytokines genes iL-1 β, iL-6, iL-8 and TNF- α was revealed - in BmCC on 1 - 3 day after immunization, and in SCC – up to 15 days. in CBA mice injected with polyvinylpyrrolidone (PVP) CFE and number of CFU-F in BmCC and SCC increased 1, 9 and 1, 8 times only and expression of genes iL-6, iL-8 and TNF- was observed only on the first day. in СВА/N xid mice there was neither increase CFU-F in the corresponding organs, nor expression of proinflammatory cytokines genes in primary cultures. The data suggest the possibility of positive participation of stromal cells in the development on of immune response in organism. Degree of activation of stromal tissue in immunized mice, apparently, correlates with the degree of immune response, supposing a close relationship between stromal tissue and immune system.

关键词： Stromal Cells-immunity

Virus entry mediated by hepatitis B virus envelope proteins

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World Journal of Gastroenterology 2013年第40期19卷 6730-6734页

作者： John m Taylor Fox Chase Cancer Center PhiladelphiaPA19111United States

Hepatitis B virus(HBV),a major cause of human liver disease worldwide,encodes three envelope proteins needed for the attachment and entry of the virus into susceptible host cells.A second virus,hepatitis delta virus,which is known to enhance liver disease in HBV infected patients,diverts the same HBV envelope proteins to achieve its own assembly and *** the lab,lentiviral vectors based on human immunodeficiency virus type 1 can be assembled using the HBV envelope proteins,and will similarly infect susceptible *** article provides a partial review and some personal reflections of how these three viruses infect and of how recipient cells become susceptible,along with some consideration of questions that remain to be answered.

关键词： Hepatitis B virus Hepatitis delta virus Receptor Envelope proteins Entry

Occurrence and Distribution of <i>Banana bunchy top virus</i>Related Agro-Ecosystem in South Western, Democratic Republic of Congo

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American Journal of Plant Sciences 2014年第5期5卷 647-658页

作者： Lyna Fama Tongo mukwa m. muengula i. Zinga A. Kalonji m. L. iskra-Caruana C. Bragard Centre international de Recherche Agronomique pour le Développement Montpellier France Clinique des Plantes de Kinshasa Kinshasa Democratic Republic of the Congo Earth and Life institute Applied Microbiology-Phytopathology Université Catholique de Louvain Louvain-la- Neuve Belgium Faculté des Sciences Agronomiques de l’Université de Kinshasa Kinshasa Democratic Republic of the Congo Laboratoire des Sciences Biologiques et Agronomiques pour le Développement (LASBAD) Université de Bangui Bangui Central African Republic

Banana bunchy top virus (BBTV) is one of the most severe and widespread virus limiting production and distribution of planting material of banana (musa spp.) crops in the world. in Democratic Republic of Congo (DRC), these crops play a major role in daily life of almost 70% of citizen. many factors influence banana production negatively such as Banana bunchy top disease. Epidemiological survey was conducted in experimental stations and farmers’ fields for two consecutive seasons covering 72 sites in five provinces of south western of RDC. The objective of this study was to evaluate the presence and distribution of the Banana bunchy top virus in five provinces of South Western of DRC, with emphasis on the agro-ecological factors. A total of 174 musa spp. leaves samples were collected and analyzed by PCR. The results revealed the presence of BBTV in all provinces investigated. The frequency of BBTV was 6.3% in Bandundu, 12.1% in Kasa?Oriental, 17.8% Bas Congo, 1.1% in Katanga and 7.5% Kinshasa Urban and Peri-urban. Results also revealed that BBTV occurred in experimental station and farmers’ fields, both having all cooking and dessert bananas. The high prevalence of BBTV seemed to be linked to multiple introductions of planting materials in the Bas Congo province during 1990 and 2002. However, the province of Katanga had not experienced the introduction of planting material. This factor would explain the lowest prevalence of Banana bunchy top virus in this province. The results indicated that there was a real need to facilitate access to genetically improved and healthy certified planting material in these provinces.

关键词： Banana Banana bunchy top virus (BBTV) Farmers’ Fields Agro-Ecological Conditions Democratic Republic of Congo

Tribological and vibrational characteristics of AiSi 316L tested at elevated temperature and 600 Torr vacuum

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Defence Technology（防务技术） 2019年第1期15卷 58-64页

作者： K.Arul Raj m.P.Arunkumar P.K.C.Kanigalpula m.Karthikeyan Department of mechanical Engineering Koneru Lakshmaiah Education Foundation Department of mechanical Engineering RajaRajeswari College of Engineering

Friction and wear studies enable the investigation of material interaction between two sliding surfaces in contact. in the present investigation, the coefficient of friction and the wear resistance of AiSi 316 L parts were studied under self-mating, dry sliding conditions using a pin-on-disc type configuration. The experiments were conducted at vacuum based high temperature pin-on-disc tribometer. The 4 mm diameter pin and 180 mm diameter disc were subjected to varying sliding velocities(0.5, 0.75 and 1.5 m/s) and were operated in 200, 400, 500 and 580 ℃ temperature at 600 Torr vacuum. The variation of specific wear rates with sliding velocities and different environmental conditions was studied. The morphology of sliding/rubbed surfaces was observed using Scanning Electron microscope. in summary, it was found that a severe to mild wear transition occurred in sliding under operating conditions. increased wear rates have been observed for 500 and 580 ℃ with increasing sliding velocity. Adhesive wear has been found to be predominant at 500 and 580 ℃ where as de-lamination has been observed at ambient temperature,200 and 400 ℃ in vacuum. The present paper also carried out the numerical analysis of the vibration behavior of AiSi 316 L under thermal environment. Results revealed that at high temperature vibrational amplitude and natural frequency is significantly reduced. This can be attributed to the reduction in stiffness of the material at elevated temperatures. This high amplitude vibration during service can lead to high wear rate.

关键词： Pin-on-disc Sliding wear Vacuum De-lamination Scanning electron microscope Vibration

A Case Report of Orf Disease in a Greek island: Diagnostic Tests or interventions Are Not Necessary

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modern Research in inflammation 2014年第2期3卷 67-69页

作者： m. Lalountas A. Kriari C. Asteriou i. Tornikidis P. Lazaridis Department of Cardiothoracic Surgery AHEPA University Hospital Thessaloniki Greece Surgical Department General Hospital Health Centre of Lemnos Lemnos Greece

The Orf disease, also known as contagious ecthyma, is a zoonotic infection caused by a dermatotropic parapoxvirus that commonly infects small ruminants such as sheep and goats. it is transmitted to humans through contact with an infected animal or fomites. Human infection typically is associated with occupational animal contact. We recently treated a healthy 41-year-old woman who presented a hangnail lesion on the middle finger of her right hand. The lesion was hard cauliflower-like mass, granulomatous and painful. Surgical debridement and biopsy were performed for further investigation. The Orf disease is usually self-limiting and resolves in 6 - 10 weeks, but complications may occur. The diagnosis may be confirmed by electron microscopy, conventional histopathology or by isolation of the virus by PCR. Early clinical recognition and knowledge of this benign viral condition are vital to avoid unnecessary surgical intervention.

关键词： Orf Disease Parapoxvirus Contagious Ecthyma Hand Treatment