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Clinical outcome of pediatric and young adult subclinical varicoceles:a single-institution experience

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Asian journal of Andrology 2021年第6期23卷 611-615页

作者： Patricia S cho Richard N Yu Harriet j Paltiel matthew A migliozzi Xiaoran Li Alyssia Venna David A Diamond Department of Urology University of Massachusetts Medical SchoolWorcesterMA 01655USA Department of Urology Boston Children's HospitalBostonMA 02115USA Department of Radiology Boston Children's HospitalBostonMA 02115USA

Subclinical varicocele represents an abnormality of veins of the pampiniform plexus on scrotal ultrasound(US)without a clinically palpable *** significance remains *** guidelines do not recommend surgical intervention,clinical management is *** there is limited information on long-term outcome of subclinical varicoceles due to challenges in diagnosis and management,we performed a single-institution,retrospective review of patients from October 1999 to October 2014 with subclinical varicocele and with available US studies reviewed by a single *** varicocele was defined as dilation of the pampiniform venous plexus on US involving≥2 vessels with diameter>2.5 mm,without clinical varicocele on physical examination or prior inguinal ***-six of 98 patients identified were confirmed as having a subclinical varicocele and *** mean age at initial visit was 15.5 years,with a mean follow-up of 26.5 *** majority were right-sided(69.4%,n=25),usually with a contralateral clinical *** asymmetry(>20%volume difference of the affected side by testicular atrophy index formula)was assessed in 9 patients with unilateral subclinical varicocele without contralateral clinical or subclinical varicocele and observed in 1 *** 17 patients with follow-up,3(17.6%)progressed to clinical varicocele without asymmetric testicular volume,as most remained subclinical or resolved without *** our experience,subclinical varicoceles appeared unlikely to progress to clinical varicoceles,to affect testicular volume,or to lead to *** our study is limited in numbers and follow-up,this information may aid clinical management strategies and guide future prospective studies.

关键词： adolescent pediatric subclinical varicocele

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

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Applied mathematics and mechanics(English Edition) 2024年第3期45卷 407-424页

作者： m.SAFI m.VAKILIFARD m.j.mAHmOODI Faculty of Civil Water&Environmental EngineeringShahid Beheshti UniversityTehran ***Iran Faculty of mechanical and Energy Engineering Shahid Beheshti UniversityTehran ***Iran

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency *** different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into ***,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss *** the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COmSOL *** parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse *** results show that considering the rubber viscoelasticity enhances the wave attenuation ***,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal *** 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.

关键词： layered metamaterial periodic foundation complex dispersion curve wave transmission diagram

Thermal Characteristics,mechanical Properties,In Vitro Degradation and Cytotoxicity of Novel Biodegradable Zn-Al-mg and Zn-Al-mg-xBi Alloys

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Acta metallurgica Sinica(English Letters) 2017年第3期30卷 201-211页

作者： H.R.Bakhsheshi-Rad E.Hamzah H.T.Low m.H.cho m.Kasiri-Asgarani S.Farahany A.mostafas m.medraj Advanced materials Research Center Department of Materials Engineering Najafabad Branch Islamic Azad University Najafabad Iran Department of materials Manufacturing and Industrial Engineering Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310 Johor Bahru Johor Malaysia Research and Development Centre KISWIRE Sdn. BhdJohor Bahru Johor Malaysia Department of materials and mechanical Engineering Buein Zahra Technical University Qazvin *** Iran Department of mechanical and materials Engineering Masdar Institute of Science and TechnologyP. O. Box: 54224 Masdar City Abu Dhabi UAE Department of mechanical Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal QCH3G 1MS Canada

Ternary Zn-0.5A1-0.5mg and quatemary Zn-0.5A1-0.5mg-xBi （x = 0.1, 0.3 and 0.5） alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation behavior. Thermal analysis and microstructural observations showed that Zn-0.5A1-0.5mg is composed of FCC-A1 ＋ HCP- Zn ＋ mg2（Zn,A1）ll while a new phase a-mg3Bi2 appeared after the addition of Bi to the Zn-0.5A1-0.5mg ternary alloy. The results revealed that the quaternary Zn-A1-mg-Bi alloys have higher tensile strength, elongation and hardness but slightly lower corrosion resistance than those of the temary Zn-AI-mg alloy. Based on the mTT assay, the Zn-A1-mg and Zn-A1-mg-Bi alloys were found to be biocompatible, and thus, they can be considered for further investigation in an in vivo environment.

关键词： Zn-AI-mg-Bi microstructure mechanical property Corrosion Cytotoxicity

Health risk of whole body vibration in mining trucks during various operational conditions

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journal of Central South University 2017年第8期24卷 1808-1816页

作者： Rahimdel m.j mirzaei m Sattarvand j Hoseinie S.H Department of mining Engineering Sahand University of TechnologyTabriz ***Iran Department of mechanical Engineering Sahand University of TechnologyTabriz ***Iran Department of mining Engineering Isfahan University of TechnologyIsfahan ***Iran

mining machineries are generally exposed to intensive vibrations in harsh mining environment. If vibrations are beyond the tolerable limit, the machine and its operator health will be under the risk. In this work, the vibration of a mining truck at different operational conditions are simulated and discussed. To achieve this aim, three haul roads with low, medium and poor qualities are considered based on the ISO standard. Accordingly, the vibration of a mining truck in different speeds, payload and distribution qualities of materials in the dump body are evaluated in each haul road quality using Trucksim software. The simulation results with statistical discussions indicate that the truck speed and the materials distribution quality have significant effects on the root mean square(RmS) of vertical vibrations. However, the effect of the payload is not considerable on the RmS. moreover, the accumulation of materials on the rear side of the truck dump body is efficient on the vibrational health risk.

关键词： mining trucks operational conditions health risk whole body vibration

model-Based Integrated methods for Quantitative Estimation of Soil Salinity from Hyperspectral Remote Sensing Data:A Case Study of Selected South African Soils

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Pedosphere 2012年第5期22卷 640-649页

作者： Z. E. mASHImBYE m. A. cho j. P. NELL W. P. DE CLERCQ A. VAN NIEKERK D. P. TURNER Department of Soil Science Stellenbosch University Private Bag X1 Matieland 7602 (South Africa) Agricultural Research Council-Institute for Soil Climate and Water Private Bag X79 Pretoria 0001 (South Africa) Department of Geography and Environmental Studies Stellenbosch University Private Bag X1 Matieland 7602 (South Africa) Council for Scientific and Industrial Research Natural Resources and the Environment P.O. Box 395 Pretoria 0001 (South Africa) School of Environmental Science University of Kwazulu-Natal Westville Campus Westville 3630 (South Africa)

Soil salinization is a land degradation process that leads to reduced agricultural yields. This study investigated the method that can best predict electrical conductivity (EC) in dry soils using individual bands, a normalized difference salinity index (NDSI), partial least squares regression (PLSR), and bagging PLSR. Soil spectral reflectance of dried, ground, and sieved soil samples containing varying amounts of EC was measured using an ASD FieldSpec spectrometer in a darkroom. Predictive models were computed using a training dataset. An independent validation dataset was used to validate the models. The results showed that good predictions could be made based on bagging PLSR using first derivative reflectance (validation R2 = 0.85), PLSR using untransformed reflectance (validation R2 = 0.70), NDSI (validation R2 = 0.65), and the untransformed individual band at 2257 nm (validation R2 = 0.60) predictive models. These suggested the potential of mapping soil salinity using airborne and/or satellite hyperspectral data during dry seasons.

关键词： electrical conductivity land degradation partial least squares regression salinity index spectral reflectance

Surface morphology and impurity distribution of electron beam recrystallized silicon films on low cost substrates for solar cell absorber

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Rare metals 2006年第z1期25卷 195-200页

作者： GROmBALL F müLLER j Department of mikrosystemtechnik Technische Universitt Hamburg-Harburg Hamburg 21073 Germany

A line shaped electron beam recrystallised polycrystalline silicon film on the low cost substrate was investigated for the use of the solar cell absorber. The applied EB energy density strongly influences the surface morphology of the film system. Lower EB energy density results in droplet morphology and the rougher SiO2 capping layer due to the low fluidity. With the energy increasing, the capping layer becomes smooth and continuous and less and small pinholes form in the silicon film. Tungstendisilicide (WSi2) is formed at the interface tungsten/silicon but also at the grain boundaries of the silicon. Because of the fast melting and cooling of the silicon film, the eutectic of silicon and tungstendisilicide mainly forms at the grain boundary of the primary silicon dendrites. The SEm-EDX analysis shows that there are no chlorine and hydrogen in the area surrounding a pinhole after recrystallization because of outgassing during the solidification.

关键词： polycrystalline silicon film solar cell recrystallization energy surface morphology outgassing

Dynamic mechanical Relaxation in Bulk metallic Glasses:A Review

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journal of materials Science & Technology 2014年第6期30卷 523-545页

作者： j.C.Qiao j.m.Pelletier Université de Lyon CNRS France INSA-Lyon MATEIS UMR5510 F-69621 Villeurbanne France

metallic glasses have aroused considerable interest in the past decades because they exhibit fascinating properties. First, this article briefly outlines the mechanical, thermal properties and application of the metallic glasses. In addition, we focus on the dynamic mechanical relaxation behaviors, i.e. main （α） and secondary （β） relaxations, in metallic glasses. The mechanical relaxation behaviors are connected to the mechanical properties and physical properties in glassy materials. The main relaxation in glassy materials is related to the glass transition phenomenon and viscous flow. On the other hand, the β relaxation is linked to many fundamental issues in metallic glasses. In these materials relaxation processes are directly related to the plastic deformation mechanism. The mechanical relaxations, particularly, the β relaxation provides an excellent opportunity to design metallic glasses with desired physical and mechanical properties. We demonstrate the universal characteristics of main relaxation in metallic glasses. The phenomenological models and the physical theories are introduced to describe the main relaxation in metallic glasses. In parallel, we show the dependence of the α. and β relaxations on the thermal treatments in metallic glasses. Finally, we analyze the correlation between the atomic mobility and the thermo-mechanical treatments in metallic glasses. On the one hand, the atomic mobility in metallic glasses is reduced by physical aging or crystallization. On the other hand, the atomic mobility in metallic glass is enhanced by deformation （i.e. compression and cold rolling）. Importantly, to analyze the atomic mobility in amorphous materials, a physical theory is introduced. This model invokes the concept of quasi-point defects, which correspond to the density fluctuations in the glassy materials.

关键词： metallic glasses mechanical properties main relaxation Secondary relaxation Physical analysis

Use of silica nanopowder to accelerate CO_2 sorption by Ca(OH)_2

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Particuology 2013年第4期11卷 448-453页

作者： m.A.S.Quintanilla j.m.Valverde Faculty of Physics University of SevilleAvenida Reina Mercedes s/n

Promising technologies have recently emerged to capture CO2 from postcombustion flue gas and to enhance the production of hydrogen from natural gas by steam-methane reforming, on the basis of sorp- tion of CO2 by Ca-based powders. The rate of CO2 sorption on Ca-based powders is limited by both carbonation kinetics and transport of CO2 to unreacted sorption sites. Ca-based powders may exhibit cohesive aggregation, thus hindering gas-solids contact efficiency. In our work, we tested the sorption rate of powder samples prepared by dry mixing of a cohesive Ca（OH）2 powder with a silica nanopowder used as additive. The silica nanopowder serves to improve the dispersibility of Ca（OH）2. Consequently, when a CO2 enriched gas and the modified sorbent are brought into contact, the rate of CO2 sorption is enhanced in the initial fast phase of interest for practical applications.

关键词： FluidizationFine powdersCO2 sorptionNanoparticles

Effect of Annealing Atmosphere on the mechanical Property of Free-cutting Phosphor Bronze Alloy

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journal of materials Science & Technology 2008年第1期24卷 115-119页

作者： Byoung-Soo Lee Hoon cho Hyung-Ho jo Nano material Team Advanced Material Division Korea Institute of Industrial Technology Incheon 406-800 Korea

The present work is focused on the influence of annealing atmosphere on the microstructure and mechanical property of free-cutting phosphor bronze *** annealing of the alloy was conducted in the three kinds of annealing atmosphere such as air,vacuum and *** annealing,a discernable difference in recystallized grain size and lead particle size was not appeared with different annealing *** tensile strength of the alloy annealed in air or nitrogen atmosphere was higher than that of those annealed in vacuum *** thecase of the alloy annealed in vacuum atmosphere,the mechanical strength was reduced by vaporization of *** the case of annealing in nitrogen and in air atmosphere,the sweating of lead was ***,the inverse segregation of lead was suppressed by copper oxide layer on the surface annealed in *** copper oxide layer leads to a decrease of the yield during fabrication process. Therefore,annealing of the alloy in nitrogen atmosphere is favorable in terms of the mechanical strength and yield.

关键词： Free-cutting Phosphor bronze alloy Inverse segregation Vaporization Sweating