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A comparison of electromigration failure of metal lines with fracture mechanics

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Acta mechanica Sinica 2012年第3期28卷 774-781页

作者： Hiroyuki abé mikio muraoka Kazuhiko Sasagawa masumi Saka Tohoku University Sendai 980-8579Japan Department of mechanical Engineering Akita UniversityTegatagakuen-machi 1-1Akita 010-8502Japan Department of Intelligent machines and System Engineering Hirosaki UniversityBunkyo-cho 3Hirosaki 036-8561Japan Department of nanomechanics Tohoku UniversityAoba 6-6-01AramakiAoba-kuSendai 980-8579Japan

Atoms constructing an interconnecting metal line in a semiconductor device are transported by electron flow in high density. This phenomenon is called electromigration, which may cause the line failure. In order to characterize the electromigration failure, a comparison study is carded out with some typical phenomena treated by fracture mechanics for thin and large structures. An example of thin structures, which have been treated by fracture mechanics, is silica opti- cal fibers for communication systems. The damage growth in a metal line by electromigration is characterized in compar- ison with the crack growth in a silica optical fiber subjected to static fatigue. Also a brief comparison is made between the electromigration failure and some fracture phenomena in large structures.

关键词： Electromigration failure. Interconnecting line Comparison Fracture mechanics

new antiglycation and enzyme inhibitors from Parmotrema cooperi

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Science China Chemistry 2011年第12期54卷 1926-1931页

作者： m.Iqbal CHOUDHARY meher ALI Atia-tul-wahab Ajmal KHAn Saima RASHEED Sajan Lal SHYAULA(Shrestha) Atta-ur-RAHmAn H.E.J.Research Institute of Chemistry International Center for Chemical and Biological SciencesUniversity of Karachi Dr.Panjwani Center for molecular medicine and Drug Research International Center for Chemical and Biological SciencesUniversity of Karachi Department of Chemistry College of ScienceKing Saud University nepal Academy of Science and Technology

Lichens are unique individuals which have been widely used in traditional medicines. This study was focused on the bioassayguided phytochemical investigation, and bioactivity evaluation on a lichens species, Parmotrema cooperi. This first bioassaydirected chemical study on P. cooperi has led to the isolation of ethyl heamatomate （1）, atraric acid （2）, ethyl orsellinate （3）, orsellinic acid （4）, lecanoric acid （5）, gyrophoric acid （6）, and licanorin （7）. The structures of 1-7 were mainly elucidated from spectroscopic methods including 1D, and 2D nmR spectroscopy, and mass spectrometry. These compounds were evaluated for their antiglycation, urease, a-chymotrypsin, and β-glucoronidase inhibitory activities. Few of the phenolic compounds showed significant, while most of them showed good inhibition of protein glycation, and urease activities.

关键词： lichen Parmotrema cooped ethyl heamatomate atraric acid urease inhibition antiglycation

A Fully Coupled Thermomechanical model of Friction Stir Welding(FSW) and numerical Studies on Process Parameters of Lightweight Aluminum Alloy Joints

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Acta metallurgica Sinica(English Letters) 2018年第1期31卷 1-18页

作者： Saad B.Aziz mohammad W.Dewan Daniel J.Huggett muhammad A.wahab Ayman m.Okeil T.Warren Liao Department of mechanical and Industrial Engineering Louisiana State University Department of Civil and Environmental Engineering Louisiana State University

This paper presents a new thermomechanical model of friction stir welding which is capable of simulating the three major steps of friction stir welding （FSW） process, i.e., plunge, dwell, and travel stages. A rate-dependent Johnson- Cook constitutive model is chosen to capture elasto-plastic work deformations during FSW. Two different weld schedules （i.e., plunge rate, rotational speed, and weld speed） are validated by comparing simulated temperature profiles with experimental results. Based on this model, the influences of various welding parameters on temperatures and energy generation during the welding process are investigated. numerical results show that maximum temperature in FSW process increases with the decrease in plunge rate, and the frictional energy increases almost linearly with respect to time for different rotational speeds. Furthermore, low rotational speeds cause inadequate temperature distribution due to low frictional and plastic dissipation energy which eventually results in weld defects. When both the weld speed and rotational speed are increased, the contribution of plastic dissipation energy increases significantly and improved weld quality can be expected.

关键词： Aluminum alloy Friction stir welding Temperature distribution Plastic energy Frictional energy Rate-dependent model Friction modeling

Some Arithmetic on the Hardy Sums s_2(h,k) and s_3(h,k)

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Acta mathematica Sinica,English Series 2004年第2期20卷 193-200页

作者： mümün CAn Department of mathematics Akdeniz University07058AntalyaTurkey

In this work, Rademacher’s two questions about Dedekind sums are applied to the Hardy sums s 2(h, k) and s 3(h, k). Some relations between these sums are obtained and some inequalities are given.

关键词： Dedekind Sums Hardy Sums

On the dielectric response function and dispersion relation in strongly coupled magnetized dusty plasmas

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Chinese Physics B 2018年第10期27卷 465-470页

作者： m Shahmansouri n Khodabakhshi Department of Physics Faculty of ScienceArak University

Using the generalized viscoelastic fluid model, we derive the dielectric response function in a strongly coupled dusty magnetoplasma which reveals two different dust acoustic（DA） wave modes in the hydrodynamic and kinetic limits. The effects of the strong interaction of dust grains and the external magnetic on these DA modes, as well as on the shear wave are examined. It is found that both the real and imaginary parts of DA waves are significantly modified in strongly coupled dusty magnetoplasmas. The implications of our results to space and laboratory dusty plasmas are briefly discussed.

关键词： dusty plasma strongly coupled plasma magnetoplasma dielectric response function

novel CYP1B1 mutations and a possible prognostic use for surgical management of congenital glaucoma

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International Journal of Ophthalmology(English edition) 2019年第4期12卷 607-614页

作者： mohamed m.Khafagy nadia El-Guendy marwa A Tantawy mohamed A.Eldaly Hala m.Elhilali abdel Hady A.abdel wahab Ophthalmology Department Faculty of Medicine Cairo University Cancer Biology Department National Cancer Institute Cairo University Research Department Children's Cancer Hospital

AIm: To identify CYP1B1 gene mutations and evaluate their possible role as a prognostic factor for success rates in the surgical management of Egyptian congenital glaucoma ***: Totally 42 eyes of 29 primary congenital glaucoma patients were operated on with combined trabeculotomy/trabeculectomy with mitomycin-C and followed up at 1 d, 1 wk, 1, 6 and 12 mo postoperatively. Genomic DnA was extracted from peripheral blood leukocytes. Coding regions of CYP1B1 gene were amplified using 13 pairs of primers, screened for mutations using single-strand conformation polymorphism followed by sequencing of both strands. Efficacy of the operation was graded as either a success [maintaining intraocular pressure(IOP) less than 21 mm Hg with or without antiglaucoma medication], or a failure(IOP more than 21 mm Hg with topical antiglaucoma medications). RESULTS: Seven novel mutations out of a total of 15 different mutations were found in the CYP1B1 genes of 14 patients(48.2%). The presence of CYP1B1 gene mutations did not correlate with the failure of the surgery(P=0.156, odds ratio=3.611, 95%CI, 0.56 to 22.89); while the positive consanguinity strongly correlated with failure of the initial procedure(P=0.016, odds ratio=11.25, 95%CI, 1.57 to 80.30). However, the Kaplan-meier survival analysis revealed a significantly lower time of IOP control in the subgroup with mutations in CYP1B1 versus the congenital primary glaucoma group without mutations(log rank test, P=0.015).COnCLUSIOn: Seven new CYP1B1 mutations are identified in Egyptian patients. Patients harboring confirmed mutations suffered from early failure of the initial surgery. CYP1B1 mutations could be considered as a prognostic factor for surgery in primary congenital glaucoma.

关键词： CYP1B1 mutations primary congenital glaucoma intraocular pressure trabeculotomy/trabeculectomy with mitomycin-C.

DETECTIOn OF ELECTROmAGnETIC InCLUSIOnS USInG TOPOLOGICAL SEnSITIVITY

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Journal of Computational mathematics 2017年第5期35卷 642-671页

作者： abdul wahab Tasawar abbas naveed Ahmed Qazi muhammad Zaigham Zia Bio Imaging and Signal Processing Lab. Department of Bio and Brain Engineering Korea Advanced Institute of Science and Technology 305-701 Daejeon Korea Department of mathematics and Statistics Faculty of Basic and Applied Sciences International Islamic University 44000 Islamabad Pakistan Weierstrass Institute for Applied Analysis and Stochastics Leibniz Institute in Forschungsverbund Berlin e. V. (WIAS) Mohrenstr. 39 10117 Berlin Germany Department of mathematics COMSATS Institute of Information Technology Islamabad Campus Park Road Chak Shahzad 44000 Islamabad Pakistan

In this article, a topological sensitivity framework for far-field detection of a diamet- rically small electromagnetic inclusion is established. The cases of single and multiple measurements of the electric far-field scattering amplitude at a fixed frequency are tak- en into account. The performance of the algorithm is analyzed theoretically in terms of its resolution and sensitivity for locating an inclusion. The stability of the framework with respect to measurement and medium noises is discussed. moreover, the quantitative results for signal-to-noise ratio are presented. A few numerical results are presented to illustrate the detection capabilities of the proposed framework with single and multiple measurements.

关键词： Electromagnetic imaging Topological derivative Localization Resolution analysis Stability analysis medium noise measurement noise.

Impact of Friction Stir Welding (FSW) Process Parameters on Thermal modeling and Heat Generation of Aluminum Alloy Joints

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Acta metallurgica Sinica(English Letters) 2016年第9期29卷 869-883页

Friction stir welding （FSW） is a solid-state joining process, where joint properties largely depend on the amount of heat generation during the welding process. The objective of this paper was to develop a numerical thermomechanical model for FSW of aluminum--copper alloy AA2219 and analyze heat generation during the welding process. The thermomechanical model has been developed utilizing AnSYS APDL. The model was verified by comparing simulated temperature profile of three different weld schedules （i.e., different combinations of weld parameters in real weld situations） from simulation with experimental results. Furthermore, the verified model was used to analyze the effect of different weld parameters on heat generation. Among all the weld parameters, the effect of rotational speed on heat generation is the highest.

关键词： Friction stir welding Frictional dissipation energy Temperature distribution Friction modeling Aluminum alloy

Atmospheric pressure gliding arc discharge plasma treatments for improving germination, growth and yield of wheat

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Plasma Science and Technology 2018年第11期20卷 90-100页

作者： n C ROY m m HASAn A H KabIR m A REZA m R TALUKDER A n CHOWDHURY Plasma Science and Technology Laboratory Department of Applied Physics and Electronic EngineeringUniversity of Rajshahi Rajshahi 6205 Bangladesh Department of Agronomy and Agricultural Extension University of Rajshahi Rajshahi 6205 Bangladesh Depatment of Botany University of Rajshahi Rajshahi 6205Bangladesh Department of Genetic Engineering and Biotechnology University of Rajshahi Rajshahi 6205Bangladesh Bangladesh Council of Scientific and Industrial Research Laboratory Rajshahi Rajshahi 6206Bangladesh

Wheat （Triticum aestivum） seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ,--20% by 6 min treatment with H2O/O2 plasma with respect to control.

关键词： atmospheric pressure gliding arc discharge plasmas wheat germination growth improvement total soluble protein