检索结果-南通市图书馆

Development of Powder Metallurgy （PM） Compacted Cu-TaC Electrodes for EDM

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Journal of Mechanics Engineering and Automation 2011年第5期1卷 385-391页

作者： Mohammed Baba Ndaliman ahsan Ali Khan Department of Manufacturing and Materials Engineering Kulliyyah of Engineering International lslamic University Malaysia P. O.

The main aim of this paper is to investigate the properties of Cu-TaC electrodes produced by Powder Metallurgy （PM） method. The design of Experiment （DOE） method was used to plan the investigation. Two different compositions of the powders （Cu-TaC with 30 and 55 % wt TaC） were used. The major properties which determine suitability of electrodes for Electro Discharge Machining （EDM） are electrical conductivity, therrnal conductivity and to some extent density. These properties were measured for the green compacted electrodes, analyzed and compared with their sintered counterparts. This is the initial stage to determine the suitability or otherwise of the compacted electrodes. The results showed that the compacted electrodes in green form can be suitable for EDM, since the electrical conductivities are very high （94.96-189.92Ω^-1m^-1）. The thermal conductivity is good （29.70-33.20W/m K）. The density ranges between 6.13 and 9.80 g/cm3. The sintered electrodes were found to be unsuitable at the specified conditions, because they became non-conductive electrically after sintering. Current efforts are geared towards improving these properties for the sintered ones and also determining their optimum levels.

关键词： Powder metallurgy (PM) green compact Cu-TaC thermal conductivity electrical conductivity density EDM (electrodischarge machining).

纳米颗粒的工程配方药物递送的快速纳米沉淀（FNP）

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

纳米颗粒的工程配方药物递送的快速纳米沉淀（FNP）

作者： Bilal ahsan（贝劳）华东理工大学

学位级别：硕士

这项研究为开发和提供具有稳定尺寸分布的纳米颗粒稳定性的方法提供了基本理解。在这里,我们将演示快速纳米沉淀(FNP)方法,动力学调节和快速沉淀机理。这项最新技术可用于制造尺寸和分布均正确控制的有机和无机纳米颗粒,这些纳米颗粒被... 详细信息

这项研究为开发和提供具有稳定尺寸分布的纳米颗粒稳定性的方法提供了基本理解。在这里,我们将演示快速纳米沉淀(FNP)方法,动力学调节和快速沉淀机理。这项最新技术可用于制造尺寸和分布均正确控制的有机和无机纳米颗粒,这些纳米颗粒被生物相容性和可生物降解的聚合物所覆盖。可以通过调节溶剂沉淀过程中的溶质成核和生长水平来调节所得纳米颗粒(NP)的大小。对于FNP,已经研究了特定用途,包括用于药物和可视化设备的NP制备。该研究解决了各种标准,超饱和度要求以及使用FNP调节NP尺寸的稳定剂的选择,并提供了对现有FNP意识以及相关示例和应用的描述。闪光纳米沉淀可以随着时间延长以获取稳定的纳米颗粒,甚至获得用于纳米颗粒物质的强PDI。充电和封装性能差的问题是用于纳米粒子制备的现代直接沉淀法。FNP提供了灵活高效的生物医学工程纳米生产网络。在这种情况下,在FNP技术的基础上形成了装载吉非替尼的纳米颗粒,从而形成了动态,冷冻的纳米颗粒,具有合理的尺寸和随时间的稳定性。叶酸修饰的两亲性Dex-b-PLA用于保护共聚物,由于包含了葡聚糖嵌段和目标基团,定型的纳米颗粒(NP)分别具有良好的生物相容性和有效的细胞吸收能力。我们的研究表明,规划肺癌载药NP的现代方法表明了更多护理应用的可能性。快速纳米沉淀(FNP)可以用于随时间推移获得稳定的纳米颗粒,但是也可以用于强纳米颗粒的多分散指数(PDI)。充电和封装性能差的问题是用于纳米粒子制备的现代直接沉淀法。我们在这里演示Flash纳米沉淀(FNP)为生物医学工程提供了一种灵活的多功能纳米制造方法。该机制是动力学调节和快速沉淀的。

关键词：吉非替尼负载的纳米颗粒快速纳米沉淀基于葡聚糖的共聚物纳米封装

Melatonin mitigates cold-induced damage to pepper seedlings by promoting redox homeostasis and regulating antioxidant profiling

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Horticultural Plant Journal 2024年第2期10卷 532-544页

作者： Muhammad ahsan Altaf Yuanyuan Hao Huangying Shu Weiheng Jin Chuhao Chen Lin Li Yu Zhang Muhammad Ali Mumtaz Huizhen Fu Shanhan Cheng Guopeng Zhu Zhiwei Wang Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province Sanya Nanfan Research InstituteHainan UniversitySanyaHainan 572025China Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province School of HorticultureHainan UniversityHaikouHainan 570228China Hainan Yazhou Bay Seed Laboratory SanyaHainan 572025China

This study assessed the influence of exogenous ME in the mitigation of cold damage in pepper seedlings. Melatonin(ME) is a dynamic molecule that helps plants cope with stress in several ways. Cold stress(CS) is one of the most important environmental factors that restrict plant growth and yield. Pepper(Capsicum annuum L.) is a valuable commercial crop, highly sensitive to CS. Thus, identifying an efficient strategy to mitigate cold damage is critical for long-term pepper production. For this purpose, the roots of pepper seedlings were pretreated with ME(5 μmol · L^(-1)) and exposed to CS for 7 d. The results indicated that CS suppressed pepper growth, hampered photosynthetic capacity, and damaged root architecture in pepper plants. In contrast, the production of reactive oxygen species(ROS), malondialdehyde(MDA), electrolyte leakage(EL), proline, and soluble sugars were enhanced in plants under CS. ME(5 μmol · L^(-1)) pretreatment reduced the negative effects of CS by recovering plant growth, root traits, gas exchange elements, and pigment molecules compared to CS control treatment. Furthermore, ME application efficiently reduced oxidative stress markers [hydrogen peroxide(H_(2)O_(2)), superoxide ion(O_(2)^(·-)), EL, and MDA] while increasing proline and soluble sugar content in pepper leaves. ME application combined with CS further increased antioxidant enzymes and related gene expression. Collectively, our results confirmed the mitigating potential of ME supplementation for CS by maintaining pepper seedling growth,improving the photosynthesis apparatus, regulating pigments, and osmolyte content.

关键词： Pepper Melatonin Cold stress Antioxidant enzyme Root trait

在线全文

学校读者我要写书评

暂无评论

幺半群的内射类及投射类刻画(英文)

数学进展 2007年第3期36卷 321-326页

作者：闫统江 Jalved ahsan 费翔历肖国镇中国石油大学数学与计算科学学院西安电子科技大学综合业务数据网国家重点实验室陕西西安710071 Department of Mathematical Sciences King Fahd University of Petroleum and MineralsDhahran 31261Saudi Arabia

类比于一般环上模的内射类,定义了幺半群上的S-系的内射类和投射类,并利用它们刻画了几类特殊的幺半群．证明了完全内射幺半群和完全拟内射幺半群是等价的．并且证明了对于标致幺半群S,它是完全投射的当且仅当它是完全拟投射的当且仅当... 详细信息

类比于一般环上模的内射类,定义了幺半群上的S-系的内射类和投射类,并利用它们刻画了几类特殊的幺半群．证明了完全内射幺半群和完全拟内射幺半群是等价的．并且证明了对于标致幺半群S,它是完全投射的当且仅当它是完全拟投射的当且仅当它上面的投射S-系构成了一个投射类．

关键词：半群幺半群 S-系内射类投射类

在线全文

学校读者我要写书评

暂无评论

贸易便利化对巴基斯坦对外贸易影响研究

贸易便利化对巴基斯坦对外贸易影响研究

作者： Muhammad ahsan（大山）天津财经大学

学位级别：硕士

贸易便利化有助于提高贸易效率,促进对外贸易的更好发展。因此,深受国际组织和各国关注。巴基斯坦是一个较为落后的发展中国家,对外贸易发展水平较低,贸易对国内经济的带动作用较差。为了更好的促进巴基斯坦对外贸易,并且认识贸易便利... 详细信息

贸易便利化有助于提高贸易效率,促进对外贸易的更好发展。因此,深受国际组织和各国关注。巴基斯坦是一个较为落后的发展中国家,对外贸易发展水平较低,贸易对国内经济的带动作用较差。为了更好的促进巴基斯坦对外贸易,并且认识贸易便利化及贸易成本对巴基斯坦对外贸易的影响,本研究采用引力模型,就贸易便利化对巴基斯坦对外贸易的影响进行了分析,并探讨了贸易成本的中介效应。经过研究,主要获得了如下结论:(1)巴基斯坦贸易便利化指数较低,多个维度得分不仅低,而且在全球范围来看,排名十分落后。这就需要巴基斯坦进一步改善贸易状况,提高贸易便利化指数。(2)通过巴基斯坦贸易现状风险,发现该国进出口商品单一,尤其是出口商品单一。此外,巴基斯坦进出口贸易不均衡,贸易逆差较大,不利于贸易的持续发展。(3)经过引力模型分析,巴基斯坦贸易便利化对进口贸易和出口贸易均有显著影响。不过,具体到主要进出口商品类别来看,贸易便利化指数对相关产品进口和出口的影响并不显著。对贸易成本进行中介效应验证,发现贸易成本对巴基斯坦进口和出口贸易有负向作用,而且部分抑制贸易便利化对进出口贸易的促进作用。(4)最后基于上述研究成果,从提高贸易便利化和降低贸易成本等方面提出了相应的建议,比如加强基础设施建设,完善港口建设,采取措施降低贸易中的显形成本和隐形成本等。

关键词：巴基斯坦贸易便利化贸易成本引力模型

Interaction of ciprofloxacin hydrochloride with sodium dodecyl sulfate in aqueous/electrolytes solution at different temperatures and compositions

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第1期28卷 216-223页

作者： Sk.Md.Ali ahsan Md.Ruhul Amin Shamim Mahbub Mohammad Robel Molla Shahina Aktar Malik Abdul Rub Md.Anamul Hoque Muhammad Nadeem Arshad Mohammed Abdullah Khan Department of Chemistry Jahangirnagar UniversitySavarDhaka 1342Bangladesh Chemistry Department Faculty of ScienceKing Abdulaziz UniversityJeddah-21589Saudi Arabia Center of Excellence for Advanced Materials Research King Abdulaziz UniversityJeddah-21589Saudi Arabia

Interactions of ciprofloxacin hydrochloride(CPFH)with sodium dodecyl sulfate(SDS)were investigated by conductivity measurement in H2O/electrolyte solutions(NaCl,Na2SO4&Na3PO4)over 298.15–318.15 K temperature range(with 5 K interval)considering the human body *** all cases,two critical micelle concentrations(c*)were observed which are increased in the presence of drug and decreased in the presence of salts enunciating the presence of interaction amongst the studied ***(CPFH+SDS)system in the presence of salt,the c*values at 303.15 K and I=0.50 mmol·kg^-1 followed the order:CNaCl>CNa2SO4>***ΔG1,m0 andΔG2,m0values are found to be negative for all systems that show that the micellization process is thermodynamically ***(CPFH+SDS)system in water,theΔHm0&ΔSm0 values reveal that the micellization processes is both entropy dominated in almost all *** the occurrence of electrolytes,ΔHm0 andΔSm0 values indicate that micellization processes are both entropy&enthalpy restricted at upper temperature but it becomes totally entropy dependent at higher *** higher positiveΔSm0 values indicate the enhanced hydrophobic interaction in presence of *** enthalpy-entropy compensation was determined from the linear relationship betweenΔHm0 andΔSm0 values in every *** transfer energies as well as compensation temperature and intrinsic enthalpy were also evaluated and the behaviors were comparable to other biological system.

关键词： Ciprofloxacin hydrochloride Sodium dodecyl sulfate Critical micelle concentration Thermodynamic indices Hydrophobic effect

Facile synthesis of ironenickelecobalt ternary oxide(FNCO)mesoporous nanowires as electrode material for supercapacitor application

在线全文

学校读者我要写书评

暂无评论

Journal of Materiomics 2022年第1期8卷 221-228页

作者： Muhammad Usman Muhammad Tayyab ahsan Sofia Javed Zeeshan Ali Yiqiang Zhan Irfan Ahmed Sajid Butt Mohammad Islam Asif Mahmood M.Aftab Akram School of Chemical and Materials Engineering National University of Sciences and Technology(NUST)Sector H-12Islamabad44000Pakistan Department of Materials Science and Engineering College of EngineeringPeking University100871BeijingChina State Key Laboratory of ASIC and System Center of Micro-Nano SystemSISTFudan UniversityShanghai200433China Department of Materials Science and Engineering Institute of Space TechnologyIslamabad44000Pakistan New Mexcico Institute of Mining&Technology SocorroNM 87801USA School of Chemical and Biomolecular Engineering The University of Sydney2006SydneyAustralia

Transition Metal Oxides have drawn significant attention due to their reversible chemical redox reaction and long-life *** agglomeration and shrinkage/expansion of transition metal oxides in the nanosize regime have a noticeable effect on their electrochemical *** in this work,mesoporous nanowires(NWs)with a typical composition of iron-nickel-cobalt ternary oxide(FNCO)are synthesized using a simple,facile and cost-effective hydrothermal process followed by furnace *** NWs are then extensively investigated as an electrode material for supercapacitor *** compare the electrochemical properties,nanowires of nickel-cobalt oxide(NCO),iron-cobalt oxide(FCO)and cobalt oxide(CO)were also produced by following the same *** FNCO NWs are found to overcome the shortcomings in the electrochemical energy storage devices by exhibiting higher values of specific capacitance(2197 Fg^(-1))and energy density(109 Whkg^(-1))at 1 Ag^(-1) current ***,the FNCO NWs also showed a cyclic charge/discharge stability of 96%even up to 20,000 ***,a FNCO//graphene asymmetric device,fabricated with FNCO NWs and graphene as positive and negative electrodes,respectively,which exhibit high energy density(47 Whkg^(-1)),power density(375 Wkg^(-1))and excellent capacitance retention(86%)after 15,000 cycles.

关键词： Electrochemistry Hydrothermal synthesis Nanowires Supercapacitor Transition metal oxides

Natural compounds modulate the autophagy with potential implication of stroke

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2021年第7期11卷 1708-1720页

作者： Anil ahsan Mengru Liu Yanrong Zheng Wenping Yan Ling Pan Yue Li Shijia Ma Xingxian Zhang Ming Cao Zhanxun Wu Weiwei Hu Zhong Chen Xiangnan Zhang Institute of Pharmacology&Toxicology College of Pharmaceutical SciencesKey Laboratory of Medical Neurobiology of the Ministry of Health of ChinaZhejiang UniversityHangzhou 310058China

Stroke is considered a leading cause of mortality and neurological disability,which puts a huge burden on individuals and the *** date,effective therapy for stroke has been limited by its complex pathological *** refers to an intracellular degrading process with the involvement of *** plays a critical role in maintaining the homeostasis and survival of cells by eliminating damaged or non-essential cellular *** evidence support that autophagy protects neuronal cells from ischemic ***,under certain circumstances,autophagy activation induces cell death and aggravates ischemic brain *** naturally derived compounds have been found to modulate autophagy and exert neuroprotection against *** the present work,we have reviewed recent advances in naturally derived compounds that regulate autophagy and discussed their potential application in stroke treatment.

关键词： Autophagy Cerebral ischemia Neuroprotection Mitochondria Lysosomal activation Mitophagy Natural compounds Neurological disorders

石油与二氧化碳最小混相压力调节与控制的实验研究

在线全文

学校读者我要写书评

暂无评论

石油与二氧化碳最小混相压力调节与控制的实验研究

作者： ahsan Nabi Soomro 中国石油大学(华东)

学位级别：硕士

二氧化碳驱是提高石油采收率的重要方法之一。与非混相驱油方法相比,混相驱油的采收率更高。同时,CO驱可以将温室气体CO储存在油层中,从而减少CO排放,有利于保护环境。CO混相驱要求储层压力必须高于最小混相压力(MMP)。如果目标区块的... 详细信息

二氧化碳驱是提高石油采收率的重要方法之一。与非混相驱油方法相比,混相驱油的采收率更高。同时,CO驱可以将温室气体CO储存在油层中,从而减少CO排放,有利于保护环境。CO混相驱要求储层压力必须高于最小混相压力(MMP)。如果目标区块的地层压力小于最小混相压力,CO混相驱难以实施。如果要实施CO混相驱,一方面可以预先将目标储层的压力提高到MMP以上,另一方面可以降低目标办区块的最小混相压力以实现CO混相驱。本文以新疆砾岩油藏某拟开展CO混相驱的目标区块为研究对象,利用高温高压界面观察法MMP测量装置,在原油物性评价的基础上,开展了原油与CO最小混相压力测试及影响因素分析,并采用化学添加剂方法,评价了不同化学添加剂、浓度等对最小混相压力的影响。选择了三类添加剂,包括极性,半极性和非极性添加剂来降低最小混相压力。在极性添加剂类别中,使用乙醇。醇主要用于降低MMP值,但是,此处使用乙醇是因为其最短的非极性链。在非极性添加剂类别中,使用甲苯,甲烷和乙烷。选择该类别的原因是,二氧化碳在本质上是非极性的,而原油基本上是非极性的。因此,使用这些添加剂可以提高原油和二氧化碳的溶解度。在半极性添加剂中,使用了1-己醇。之所以使用该添加剂,是因为它具有长的非极性链,可以很容易地与CO和原油结合。所有这些改性剂的使用比例分别为1重量%,3重量%,5重量%和7重量%。结合MMP测试,还使用相同的化学改性剂进行粘度测试,以筛选还原MMP的理想添加剂或化学添加剂组合。这项研究表明,在筛选了不同浓度,不同MMP的多种添加剂和降低粘度能力后,可以将半极性和非极性两种类别的组合注射用于降低MMP。尽管该实验仅限于中油至轻油的单一原油系统,但是使用该原油筛选的添加剂可以帮助降低MMP和重油粘度。制备添加剂的最终结果组合包括2%甲苯+2%1己醇。这种新形成的组合使MMP从21.52 MPa下降到12.52 MPa,原始值降低了约42%。

关键词：最小混相压力(MMP) 化学改性剂配方 MMP降低极性添加剂非极性添加剂二氧化碳驱