检索结果-南通市图书馆

Natural Science 2022年第8期14卷 343-352页

作者： Karima Ali Hamid Albadawi Abdelbagi Talha Abdalraheem Ali Babiker Mohammed Ibrahim Malik Adam Dawoud Abakar Omer Mustafa Elsidig A Saeed mohmed bushra ahmed Elhadi Abdalla ahmed Department of Histopathology and Cytology Faculty of Medical Laboratory Sciences University of Gezira Wad Medani Sudan Department of Clinical Laboratory Sciences College of Applied Medical Sciences Jouf University Al Jouf Kingdom of Saudi Arabia Department of Medicine Faculty of Medicine University of Gezira Wad Medani Sudan Department of Medical Microbiology Faculty of Medical Laboratory Sciences University of Gezira Wad Medani Sudan

Helicobacter pylori is the microbial agent most responsible for gastro-duodenal ulcer and chronic gastritis, which can develop into carcinoma of the stomach. This study was performed in Wad Medani Teaching Hospital, Sudan to detect Helicobacter pylori in stomach samples, and evaluate the performance of the tests used, which were histological stains and PCR. Gastric biopsies were obtained from 105 referred patients during endoscopy, and fixed specimens examined by haematoxylin-eosin and Warthin-Starry silver stains, while DNA was extracted for glmM gene amplification. Epigastric pain was the most common symptom at 78% (82/105) and chronic gastritis recorded with 71% (68/105) of endoscopy results. Warthin-Starry silver stain gave 31% (33/105) as positive for Helicobacter pylori followed by glmM gene 27% (28/105) and haematoxylin-eosin 24% (25/105). The study indicated good performance of histological staining and high specificity of glmM gene in detection of Helicobacter pylori from gastric biopsies.

关键词： Helicobacter pylori Histological Stains glmM Gene Gastric Biopsy Sudan

Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2021年第2期15卷 460-472页

作者： ahmed mohmed DAFALLA Fangming JIANG Laboratory of Advanced Energy Systems Guangdong Key Laboratory of New and Renewable Energy Research and DevelopmentCAS Key Laboratory of Renewable EnergyGuangzhou Institute of Energy ConversionChinese Academy of Sciences(CAS)Guangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China

Water transport is of paramount importance to the cold start of proton exchange membrane fuel cells(PEMFCs).Analysis of water transport in cathode catalyst layer(CCL)during cold start reveals the distinct characteristics from the normal temperature *** work studies the effect of CCL mesoscopic pore-morphology on PEMFC cold *** CCL mesoscale morphology is characterized by two tortuosity factors of the ionomer network and pore structure,*** simulation results demonstrate that the mesoscale morphology of CCL has a significant influence on the performance of PEMFC cold *** was found that cold-starting of a cell with a CCL of less tortuous mesoscale morphology can succeed,whereas starting up a cell with a CCL of more tortuous mesoscale morphology may *** CCL of less tortuous pore structure reduces the water back diffusion resistance from the CCL to proton exchange membrane(PEM),thus enhancing the water storage in PEM,while reducing the tortuosity in ionomer network of CCL is found to enhance the water transport in and the water removal from *** the sake of better cold start performance,novel preparation methods,which can create catalyst layers of larger size primary pores and less tortuous pore structure and ionomer network,are desirable.

关键词： cold start energy conversion fuel cells mesoscale morphology tortuosity water management

维普期刊数据库

Multi-material Bio-inspired Soft Octopus Robot for Underwater Synchronous Swimming

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2022年第5期19卷 1229-1241页

作者： Faheem ahmed Muhammad Waqas bushra Shaikh Umair Khan Afaque Manzoor Soomro Suresh Kumar Hina Ashraf Fida Hussain Memon Kyung Hyun Choi Department of Mechatronics Engineering Jeju National UniversityJeju 63243South Korea Department of Electrical Engineering Sukkur IBA UniversityAirport RoadSukkur 65200SindhPakistan Advanced Micro Mechatronics and Energy Lab Sukkur IBA UniversitySukkur 65200Pakistan Department of Ocean Sciences Jeju National UniversityJeju 63243South Korea

Inspired by the simple yet amazing morphology of the Octopus, we propose the design, fabrication, and characterization of multi-material bio-inspired soft Octopus robot (Octobot). 3D printed molds for tentacles and head were used. The tentacles of the Octobot were casted using Ecoflex-0030 while head was fabricated using relatively flexible material, i.e., OOMOO-25. The head is attached to the functionally responsive tentacles (each tentacle is of 79.12 mm length and 7 void space diameter), whereas Shape Memory Alloy (SMA) muscle wires of 0.5 mm thickness are used in Octobot tentacles for dual thrust generation and actuation of Octobot. The tentacles were separated in two groups and were synchronously actuated. Each tentacle of the developed Octobot contains a pair of SMA muscles (SMA-α and SMA-β). SMA-α muscles being the main actuator, was powered by 9 V, 350 mA power supply, whereas SMA-β was used to provide back thrust and thus helps to increase the actuation frequency. Simulation work of the proposed model was performed in the SolidWorks environment to verify the vertical velocity using the octopus tentacle actuation. The design morphology of Octobot was optimized using simulation and TRACKER software by analyzing the experimental data of angle, displacement, and velocity of real octopus. The as-developed Octobot can swim at variable frequencies (0.5–2 Hz) with the average speed of 25 mm/s (0.5 BLS). Therefore, the proposed soft Octopus robot showed an excellent capability of mimicking the gait pattern of its natural counterpart.

关键词： Bio-inspired Octopus Octobot Sub-surface Soft robotics Swimming

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

空气流量对空冷燃料电池电堆性能的影响研究

化工学报 2022年第7期73卷 3222-3231页

作者：魏琳郭剑廖梓豪 ahmed mohmed Dafalla 蒋方明中国科学院广州能源研究所先进能源系统研究室广东广州510640 中国科学院可再生能源重点实验室广东广州510640 中国科学院大学北京100049

空冷型氢燃料电池采用开放型阴极,具有自增湿、系统简单轻便等特点。为了揭示空气流量对输出性能的影响机制,对自组装的800 W空冷型燃料电池电堆进行了实验测试和数值分析,对比了不同空气风扇转速下电堆输出电压、净功率以及传质传热特... 详细信息

空冷型氢燃料电池采用开放型阴极,具有自增湿、系统简单轻便等特点。为了揭示空气流量对输出性能的影响机制,对自组装的800 W空冷型燃料电池电堆进行了实验测试和数值分析,对比了不同空气风扇转速下电堆输出电压、净功率以及传质传热特性。结果表明:小电流条件下小空气流量可以保持电堆内较高的温度,减少活化损失,实现高净输出功率。然而,大电流条件下,小空气流量将导致电堆温度过高且分布不均匀。利用数值方法对组分和温度分布进行了可视化分析,结果表明低含水量引起的欧姆损失增加是限制输出功率的关键因素,通过提高风扇转速增加空气流量可以保证较好的冷却效果,从而提高含水量,减少欧姆损失。

关键词：燃料电池传热传质水热管理数值分析

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

交错布置蜿蜒流道的PEMFC冷启动特性

工程热物理学报 2023年第10期44卷 2798-2807页

作者：廖梓豪魏琳 ahmed mohmed Dafalla 郭剑黄旭锐蒋方明广东电网有限责任公司广州供电局广州510600 中国科学院广州能源研究所广州510640 中国科学院可再生能源重点实验室广州510640 广东省新能源和可再生能源研究开发与应用重点实验室广州510640 中国科学院大学北京100049

质子交换膜燃料电池(PEMFC)在零下温度下的冷启动是影响其市场化的重要障碍。流场构型在一定程度上决定了反应物/生成物的输运,影响着PEMFC的冷启动性能。本研究利用PEMFC冷启动模型,分析了交错布置蜿蜒流道流场(ZFFCA)、蜿蜒流道平行流... 详细信息

质子交换膜燃料电池(PEMFC)在零下温度下的冷启动是影响其市场化的重要障碍。流场构型在一定程度上决定了反应物/生成物的输运,影响着PEMFC的冷启动性能。本研究利用PEMFC冷启动模型,分析了交错布置蜿蜒流道流场(ZFFCA)、蜿蜒流道平行流场(ZPFF)和直通道平行流场(SPFF)的冷启动特性。研究发现,ZFFCA能更好地分布PEMFC内的反应物/生成物、电流密度、热和冰,交错布置的形式更进一步强化了PEMFC的传热传质,有利于冷启动成功;但使用ZFFCA在冷启动过程中PEMFC温度爬升速率较低,不利于快速冷启动。

关键词： PEM燃料电池零下温度冷启动数值仿真流场构型

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

夹紧压力对PEMFC冷启动性能的影响

工程热物理学报 2022年第4期43卷 1004-1012页

作者： ahmed mohmed Dafalla 魏琳廖梓豪 BEREKET Tsegai Habte 蒋方明中国科学院可再生能源重点实验室中国科学院广州能源研究所先进能源系统研究室广州510640 中国科学院大学北京100049

质子交换膜燃料电池(PEMFC)作为一种电化学装置,以其高效、低排放、结构紧凑、静音等优点,被认为是未来最具有潜力的发电系统,然而其在低温环境下的快速启动是车用燃料电池面临的重要挑战之一。本文采用有限元法和非等温冷启动数值模型... 详细信息

质子交换膜燃料电池(PEMFC)作为一种电化学装置,以其高效、低排放、结构紧凑、静音等优点,被认为是未来最具有潜力的发电系统,然而其在低温环境下的快速启动是车用燃料电池面临的重要挑战之一。本文采用有限元法和非等温冷启动数值模型对夹紧压力作用下PEMFC的变形及非等温冷启动过程进行了求解,分析了扩散层厚度及非均匀变形对传质传热、电流密度和冰分布以及输出电压特性的影响。结果表明,扩散层非均匀变形会增加脊下区域传质阻力,加剧氧气的不均匀分布,而位于通道下区域的阴极催化层内的反应更加剧烈,使得PEMFC升温更快,且当夹紧压力为1~2 MPa时冷启动性能最佳。

关键词：质子交换膜燃料电池夹紧压力冷启动气体扩散层数值模拟

维普期刊数据库

Alternate Two Different Modes of Actions of Green Chemicals to Combat Batrachedra amydraula Meyrick and Cadra cautella Walk on Date Palm Fruit, Egypt

在线全文

学校读者我要写书评

暂无评论

Journal of Agricultural Science and Technology(A) 2014年第6期4卷 529-534页

作者： ahmed Amin Sayed Sobhy ahmed Temerak Salah Mahmood mohmed Gameel Amr Moussa Plant Protection Research Institute Agricultural Research Center Ministry of Agricu#ure (MOA) Cairo 11728 Egypt Plant Protection Department Faculty of Agriculture Assiut University Assiut 71515 .Egypt Plant Protection Research Institute Agricultural Research Center MOA Cairo 11728 Egypt Research & Development Department Dow Agro Sciences Company Indianapolis 46268 USA

Alternate two different modes of actions of green chemicals： spinosad ＆ methoxyfenozide to combat the lesser date moth, Batrachedra amydraula and the Almond moth, Cadra cautella Walk on dates in Dakhla Oasis, New Valley, Egypt were done in 2010 and 201 I. Based on infestation of the early insect pest B. amydraula, the three-rotation program with basic 1st spray of spinosad 24 SC at 20 mL/100 L showed insignificant difference. Based on minimum effective rotation doses, alternating spinosad 24 SC at 20 mL/100 L, then methoxyfenozide 24 SC at 15 mL/100 L with two-week interval showed zero infestation and 1.8% at the last sample of 2010 and 2011, respectively. Based on infestation of the late insect pest, Cadra spp., tlhe same previous trend of the three-rotation results. Based on minimum effective rotation doses, alternating spinosad 24 SC at 20 mL/100 L, then methoxyfenozid 24 SC at 15 mL/100 L with three-week interval indicated less than 1% and 1% infestation during harvest for 2010 and 201 l, respectively. The last reflected important value when storing the fruit. Both products proved to be working under dry hot high temperatures.

关键词： Alternation green chemicals B. amydraula Cadra cautella date fruit.

Determination Uranium Concentrations and Effective Dose of Drinking Water for Nineveh Governorate—Iraq, Using Kinetic Phosphorescence Analyzer (KPA)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Protection 2014年第3期5卷 200-206页

作者： Shafik Shakier Shafik bushra Ali ahmed Mazin Mohammed Department of Physics College of Science University of Baghdad Baghdad Iraq Ministries of Environment Radiation Protection Center Baghdad Iraq

In this work, the concentrations of natural Uranium and the annual effective dose (ET in Sv·y-1) in drinking water for Nineveh Governorate in northern Iraq were determined using a pulsed-laser Kinetic Phosphorescence Analyzer (KPA). Furthermore, the relationship between pH for water samples and the concentration of Uranium was studied. The drinking water samples are taken approximately from all regions of Nineveh as;15 samples of tap water are taken from refinery stations, 13 samples of water samples are taken from wells that are used for drinking, and 18 samples of drinking water are withdrawn from wells in Adayyah region (this region is located near nuclear wastes site). Thus, the total studied samples are 46. The results of Uranium concentration for all samples ranged from 2.61 ± 0.08 to 9.14 ± 0.012 μg·L-1 with an overall average value about 5.87 ± 0.046 μg·L-1, and the total annual effective dose ranged from 2.3 to 8.04 μSv·y-1. The results also showed that the pH number increases with increasing Uranium concentration and have, in general, high values in well water.

关键词： Uranium KPA Drinking Water Intake Annual Effective Dose Nineveh

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国高校留学生跨文化适应研究

中国高校留学生跨文化适应研究

作者： bushra MOHSEN ahmed AL-QADHI 吉林大学

学位级别：硕士

目前,经济全球化迅猛发展,国际间的交流日益增强,国外申请到中国留学的留学生数量也日渐增加,为此,深入研究国际留学生的跨文化适应问题有着重要意义。本文以科琳·沃德（Colleen Ward）等人的社会文化适应和心理适应理论以及威廉·古... 详细信息

目前,经济全球化迅猛发展,国际间的交流日益增强,国外申请到中国留学的留学生数量也日渐增加,为此,深入研究国际留学生的跨文化适应问题有着重要意义。本文以科琳·沃德（Colleen Ward）等人的社会文化适应和心理适应理论以及威廉·古迪孔斯特（William Gudykunst）的沟通模式和分类形式为基础,通过微信网络平台方式进行发放问卷,利用定性和定量方法进行分析,旨在观察国际留学生在中国高校的学术适应、心理适应及社会适应现状,探究学术适应与心理适应、跨文化适应之间的相互关系,并就目前国际留学生存在的某些不适应问题提出合理化建议。研究结果表明:在学术适应方面,国际留学生适应能力较好,但对课上教师讲授内容的理解等方面存在一些困难;在社会文化适应方面,国际留学生的社会文化适应能力较弱,部分国家或地区的留学生因饮食文化及特殊节日或斋禁期间的民族习惯等难于适应留学地的统一课业作息;在心理适应方面,根据心理健康16PF量表对国际留学生知、情、行进行评估,发现一些留学生存在心理适应困难的问题,表现为:孤寂、睡眠不好、思念亲人等。通过问卷调查数据分析,本文认为国际留学生的学术追求、在地新建人际关系、交流形式及宗教信仰等与跨文化适应具有很大相关性,是否具有留学地的相关文化知识储备也是其中的重要因素。定量研究数据结果显示,社会文化适应、心理适应与学术适应呈明显的正相关。在上述调查分析的基础上,根据国际留学生在中国留学期间存在的文化、心理等适应弱的问题,提出高校管理者一方面需要了解国际留学生的生活习俗、宗教信仰,对国际留学生给予更多的社会支持与关爱;另一方面,增设跨文化培训组织,通过语言培训和社会文化培训,了解中国文化、中国制度和管理特点,帮助国际留学生尽快适应中国本土生活和高校校园文化生活,改善留学生的社会文化适应和心理适应,进而促进国际留学生本人的学术适应,保证留学生顺利完成学业。

关键词：跨文化适应国际留学生学术适应社会适应心理适应

New Sudanese Reference Chart of Fetal Bi-ometry and Weight Using Ultrasonography

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Open Journal of Radiology 2016年第2期6卷 131-139页

作者： Caroline Edward Ayad ahmed Abdelrahim Mohammed Ibrahim Mohammed Elfadil Mohammed GarElnabi bushra Hussein ahmed Elsafi ahmed Abdalla Mohammed ahmed Elshiekh Saleem College of Medical Radiological Science Sudan University of Science and Technology Khartoum Sudan Faculty of Radiology Science and Medical Imaging Alzaiem Alazhari University Khartoum Sudan College of Medical Radiological Science and Nuclear Medicine The National Rabat University Khartoum Sudan

Background: Many centers in Sudan use the reference data for fetal biometry. The recently published population-based reference either overestimated or underestimated the weight of the fetuses. Objective: To establish a national reference for fetal biometry, and weight by gestational age for singleton fetuses in Sudan. Methods: Data were collected on all singleton live births documented in the data collection sheet done at Saudi Hospital from 2015 to 2016 (n = 225). Gestational age estimation was based on the last menstrual period and fetal ultrasound thereafter. Fetal biometry and weight and other 6 fetal weight formulae were assessed. Reference data for fetal growth by gestational age were created. Results: New charts and reference equations are reported in Sudanese population for fetal biparietal diameter, head circumference, abdominal circumference and femur length and fetal weight. Conclusion: We advocate that these reference charts and equations for fetal biometry and weight might be valuable in the clinical use for appropriate ethnic Sudanese.

关键词： Fetal Biometry Fetal Weight Gestational Age Ultrasonography