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Effect of ECAP temperature on microstructure and mechanical properties of Al–Zn–Mg–Cu alloy

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Progress in Natural Science:Materials International 2016年第2期26卷 182-191页

作者： M.h.Shaeri M.Shaeri M.Ebrahimi M.T.Salehi S.h Seyyedein Department of Metallurgy and Materials Engineering Engineering Faculty Imam Khomeini International University Department of Materials Science and Engineering Sharif University of Technology Department of Mechanical Engineering University of Maragheh Department of Metallurgy and Materials Engineering Iran University of Science and Technology

The effect of equal channel angular pressing(ECAP) at different temperatures(room temperature, 120,150 and 180 °C) on microstructure and mechanical properties of Al-7075 solid solution alloy was investigated. Microstructure of the specimens was examined using orientation imaging microscopy,transmission electron microscopy as well as X-ray diffractometer, and mechanical properties were measured by Vickers microhardness and tensile tests. Microstructural investigations showed that after3 or 4 passes of ECAP, fi ne grains with average grain sizes in range of 300–1000 nm could be obtained at different ECAP temperatures. Increasing ECAP temperature from 120 to 180 °C caused a decrease in mechanical properties as a result of increasing grains and precipitates sizes, decreasing fraction of high angle boundaries and also transformation of η′ into η phase, while increasing ECAP temperature from RT to 120 °C leads to an increase in mechanical properties due to the formation of small η′ precipitates. So it can be concluded that ECAP process at 120 °C is the optimum process for attaining maximum mechanical properties. Quantitative estimates of various strengthening mechanisms revealed that the improvement of mechanical properties was mainly attributed to grain re fi nement strengthening, precipitation strengthening and dislocation strengthening.

关键词： Equal channel angular pressing Microstructure Strengthening mechanisms Mechanical properties

Update on the management of sigmoid diverticulitis

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World Journal of Gastroenterology 2021年第9期27卷 760-781页

作者： Mark h hanna Andreas M Kaiser Division of Colorectal Surgery Department of SurgeryCity of Hope National Medical CenterDuarteCA 91010-3000United States

Diverticular disease and diverticulitis are the most common non-cancerous pathology of the *** has traditionally been considered a disease of the elderly and associated with cultural and dietary *** has been a growing evolution in our understanding and the treatment guidelines for this *** provide an updated review of the epidemiology,pathogenesis,classification and highlight changes in the medical and surgical management of *** is increasingly being seen in young patients(han previously *** similarities and overlap with inflammatory bowel disease and irritable bowel syndrome *** tomography imaging represents the standard to classify the severity of *** to the traditional hinchey classification might serve to better delineate mild and intermediate forms as well as better classify chronic presentations of ***-operative management is primarily based on antibiotics and supportive measures,but antibiotics may be omitted in mild *** colonoscopy remains advisable after an acute attack,particularly after a complicated *** surgery is needed for the most severe as well as refractory cases,whereas elective resections are individualized and should be considered for chronic,smoldering,or recurrent forms and respective complications(stricture,fistula,etc.)and for patients with factors highly predictive of recurrent *** is no longer a disease of the *** evolving understanding of diverticulitis as a clinical entity has led into a more nuanced approach in both the medical and surgical management of this common ***-surgical management remains the appropriate treatment for greater than 70%of *** individuals with non-relenting,persistent,or recurrent symptoms and those with complicated disease and sequelae,a segmental colectomy remains the most effec

关键词： Diverticulitis Epidemiology Antibiotics Surgical resection Laparoscopic lavage Classification

Status and Constrain for Mechanization of Rice harvesting System in Bangladesh

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Agricultural Sciences 2017年第6期8卷 492-506页

作者： Bidhan Chandra Nath Yo-Sang Nam md. Durrul huda md. Mizanur Rahman Panna Ali Subrata Paul Farm Machinery and Postharvest Technology Division Bangladesh Rice Research Institute Gazipur Bangladesh TYM R&D Center Gongju South Korea Entomology Division Bangladesh Rice Research Institute Gazipur Bangladesh

To know the position, problems and suggestion of harvest mechanization of rice, the study conducted in 21 upzillas under seven regions (Dhaka, Mymensingh, Sylhet, Comilla, Bogra, Rajshahi and Rangpur) based on different agro-climatic condition and cropping intensity and 126 farmers participated in the interview. For collecting data, a structured questionnaire was used and statistical analysis of the collected data was carried out. In study area, the average cultivable area was 225 to 1239 decimal (1 decimal = 40 m2) and 97.60% farmer reaping by sickle and only 0.80% used combine harvester. Cut paddy transported by head (13.49%), shoulders (12.7%) or both of them of 11.11% farmer and 44.44% of farmers used small truck or field threshed. Threshing was mainly done using (49.21%) closed drum thresher and open drum thresher (26.20%), likewise 1 of 126 farmer use head-feed combine harvester. The study area, most farmers (37.3%) used kula for the cleaning of rice, but only 8.74% of farmers used winnower. In considerable amount, 80.95% of farmers had machinery, while the remaining (19.05%) did not have machines. Farmers agreed that harvesting was a labor-intensive method (35.71%) and time consuming (28.57%). Transporting of harvested paddy was dangerous and painful for head, shoulder, hand, waist, backbone, leg, etc. With mechanization and the introduction of machinery, 40.48% of farmers identified the main ceiling as the price of the machine and information/lack of credit system (21.43%). In survey area, most farmers (36.51%) identified the vital advantage of mechanized harvesting as lower labor requirement, while 21.43% of farmers said that a lower loss of rice. All farmers who participated in the interview expressed their need for machinery and mentioned agricultural credit with easy terms and conditions, subsidy for buying machinery and the ensuring of a fair market price for their rice.

关键词： Crop harvesting Mechanization

hIGh-ORDER EXPLICIT TIME-INTEGRATORS FOR DISCONTINUOUS GALERKIN DISCRETIZATIONS OF ThE MAXWELL EQUATIONS

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International Journal of Modeling, Simulation, and Scientific Computing 2013年第1期4卷 132-153页

作者： h.FAhS M.SAFA LAMA Laboratory University Paris-Est Marne-la-Vallee UMR CNRS 80505 boulevard Descartes 77454 Marne-la-Vall´ee Cedex 2France INRIA Paris-Rocquencourt Domaine de Voluceau BP.10578153 Le Chesnay CedexFrance

We investigate the practical implementation of a high-order explicit time-stepping method based on polynomial approximations,for possible application to large-scale problems in *** the spatial discretization by a high-order discontinuous Galerkin method,we obtain a linear system of differential equations of the form,∂tY(t)=hY(t)+S(t),where h is a matrix containing the spatial derivatives and t is the time *** formal solution can be written in terms of the matrix exponential,exp(th),acting on some *** introduce a general family of time-integrators based on the approximation of exp(th)by Jacobi polynomial *** discuss the efficient implementation of this technique,and based on some test problems,we compare the virtues and shortcomings of the *** also demonstrate how these schemes provide an efficient alternative to standard explicit integrators for computing solutions over long time intervals.

关键词： Maxwell’s equations discontinuous Galerkin method time-stepping schemes

熔融和辐射对垂直多孔嵌入微通道MhD混合对流换热的影响

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Journal of Central South University 2023年第11期30卷 3670-3681页

作者： A T AKINShILO A O ILEGBUSI h M ALI M SANUSI M G SOBAMOWO Department of Mechanical Engineering University of LagosAkoka-YabaLagosNigeria Department of Mechanical Engineering Yaba College of TechnologyLagosNigeria Mechanical Engineering Department King Fahd University of Petroleum and MineralsDharan 31261Saudi Arabia Interdisciplinary Research Center of Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDharan 31261Saudi Arabia Department of Mechanical Engineering Obafemi Awolowo UniversityIle-IfeOsunNigeria

研究了导电和非导电两种壁型多孔微通道的熔融和滑移效应对混合对流换热的影响。采用高阶常微分非线性耦合模型,研究了横向磁场作用下流体在微通道内注入和喷出的流动力学。这些都是在通过相似变换完成的。采用解析解的同伦摄动方法对... 详细信息

研究了导电和非导电两种壁型多孔微通道的熔融和滑移效应对混合对流换热的影响。采用高阶常微分非线性耦合模型,研究了横向磁场作用下流体在微通道内注入和喷出的流动力学。这些都是在通过相似变换完成的。采用解析解的同伦摄动方法对控制热流体输运的力学模型进行了分析,并利用已有文献在简单条件下进行了验证并得到满意的结果。研究了流体输送过程中传热流变参数的影响,以提高系统运行效率,降低能耗,从而最大限度地降低成本。结果表明,熔体和辐射对热边界层的共同作用使热边界层的厚度逐渐减小。当辐射参数(R)在1

关键词：强化传热熔融微通道辐射优化多孔介质

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SOME OBSERVATIONS ON DYNAMIC PROPERTIES OF RECEPTIVE FIELD ORGANIZATION OF COMPLEX CELLS IN CAT VISUAL CORTEX

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Science China Chemistry 1987年第1期30卷 44-54页

作者：李朝义,h.C.NOThDURFT Shanghai Institute of Physiology Academia Sinica Max-Planck-Institute for Biophysical Chemistry Goettingen West Germany

The dynamic properties of discharge fields (DFs) of the complex cells in areas 17 and 18 of cat'sbrain were observed. The sequence of activation for different areas in the DF indicated a concentric ar-rangement of latency distribution. The DE organization was proved to be dependent closely cn velocityof stimulus movement. Twin-or triple-DFs were found for some cells, each responded selectively to oneof the opposite directions of movement.

关键词： SOME OBSERVATIONS ON DYNAMIC PROPERTIES OF RECEPTIVE FIELD ORGANIZATION OF COMPLEX CELLS IN CAT VISUAL CORTEX DDF

Antihypertensive prescribing patterns in non-dialysis dependent chronic kidney disease:Findings from the Salford Kidney Study

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World Journal of Nephrology 2023年第5期12卷 168-181页

作者： Rajkumar Chinnadurai henry h L Wu Jones Abuomar Sharmilee Rengarajan David I New Darren Green Philip A Kalra Donal O’Donoghue Renal Research Centre&Department of Renal Medicine Northern Care Alliance NHS Foundation TrustSalford M68HDUnited Kingdom Department of Renal Research Kolling Institute of Medical ResearchRoyal North Shore Hospital&The University of SydneySt.Leonards(Sydney)2065New South WalesAustralia Faculty of Biology Medicine&HealthThe University of ManchesterManchester M17HRUnited Kingdom

BACKGROUND hypertension is commonly observed in patients living with chronic kidney disease(CKD).Finding an optimal treatment regime remains challenging due to the complex bidirectional cause-and-effect relationship between hypertension and *** remains variability in antihypertensive treatment *** To analyze data from the Salford Kidney Study database in relation to antihypertensive prescribing patterns amongst CKD *** The Salford Kidney Study is an ongoing prospective study that has been recruiting CKD patients since *** patients are followed up annually,and their medical records including the list of medications are updated until they reach study endpoints[starting on renal replacement therapy or reaching estimated glomerular filtration rate(eGFR)expressed as mL/min/1.73 m2≤10 mL/min/1.73 m2,or the last follow-up date,or data lock on December 31,2021,or death].Data on antihypertensive prescription practices in correspondence to baseline eGFR,urine albumin-creatinine ratio,primary CKD aetiology,and cardiovascular disease were *** between patients who were prescribed three or more antihypertensive agents and their clinical outcomes were studied by Cox regression ***-Meier analysis demonstrated differences in survival *** Three thousand two hundred and thirty non-dialysis-dependent CKD patients with data collected between October 2002 and December 2019 were *** median age was 65 years.A greater proportion of patients were taking three or more antihypertensive agents with advancing CKD stages(53%of eGFR≤15 mL/min/1.73 m2 vs 26%of eGFR≥60 mL/min/1.73 m2,Phypertensive agents was observed as the urine albumin-creatinine ratio category increased(category A3:62%vs category A1:40%,Ph the upward trends particularly noticeable in the number of individuals prescribed renin angiotensin system *** pr

关键词： hypertension Chronic kidney disease Antihypertensive agents Prescribing patterns Cardiovascular complications Renin angiotensin system blockers

Synthesis, Structural and Physical Properties of Cu1–xZnxFe2O4Ferrites

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Materials Sciences and Applications 2011年第11期2卷 1675-1681页

作者： Shahida Akhter Deba Prasad Paul md. Abdul hakim Dilip Kumar Saha md. Al-Mamun Alhamra Parveen 不详

Zn substituted Cu-Zn ferrites with a composition Cu1-xZnxFe2O4 have been synthesized by standard double sintering ceramic method and characterized by X-ray diffraction. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analyses. The lattice constant is found to increase linearly with the manganese content obeying Vegard’s law. This increase in lattice parameter is explained in terms of the sizes of component ions. It is well known that density plays a key role in controlling the properties of polycrystalline ferrites. The X-ray and bulk densities of the Cu-Zn ferrite is significantly decreased whereas porosity increased with increasing Zn concentration, thereby giving an impression that zinc might be helping in the densification of the materials. SEM micrographs exhibit a decrease in grain size with increasing Zn content. The real part of initial permeability, μ′ increase with increasing Zn contents upto x = 0.5 after that it decreases with higher Zn content.

关键词： Ferrites XRD Lattice Parameter Density Porosity Permeability

Study on Pine Wilt Disease Symptom Development in highly Sensitive Pinus massoniana Seedlings Caused by Bursaphelenchus xylophilus

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Study on Pine Wilt Disease Symptom Development in Highly Sen...