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Theoretical & Applied Mechanics Letters 2015年第3期5卷 103-106页

作者： R.D.Whalley W.M.Abed D.J.c.dennis R.J.Poole School of Engineering University of Liverpool LMFA Universite de LyonEcole Centrale de Lyon

Small concentrations of a high-molecular-weight polymer have been used to create so-called ＂elastic tur- bulence＂ in a micro-scale serpentine channel geometry. It is known that the interaction of large elastic stresses created by the shearing motion within the fluid flow with streamline curvature of the serpentine geometry leads initially to a purely-elastic instability and then the generation of elastic turbulence. We show that this elastic turbulence enhances the heat transfer at the micro-scale in this geometry by up to 300% under creeping flow conditions in comparison to that achieved by the equivalent Newtonian fluid flow.

关键词： Elastic turbulence Viscoelasticity Serpentine channel Micro-mixing Heat transfer

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固体氧化物燃料电池阴极气体传输的研究

电源技术 2007年第10期31卷 777-778,807页

作者：倪萌 LEUNG MIcHAEL K H LEUNG dennis Y c 香港大学机械工程系

建立了一个数值模型,来计算并论述在固体氧化物燃料电池(SOFc)阴极中的扩散和渗透共同作用下的传质现象。经过对比分析,研究了阴极内压力梯度对气体传输、气体分布,以及浓度过电压的影响。研究表明,文献中所采用的扩散模型可近似模拟SOF... 详细信息

建立了一个数值模型,来计算并论述在固体氧化物燃料电池(SOFc)阴极中的扩散和渗透共同作用下的传质现象。经过对比分析,研究了阴极内压力梯度对气体传输、气体分布,以及浓度过电压的影响。研究表明,文献中所采用的扩散模型可近似模拟SOFc阴极的浓度过电压。但是,对于气体成份沿阴极的分布,则必须考虑压力梯度的影响。在此提出的模型可进一步深化,以优化SOFc电极的多孔结构。

关键词：固体氧化物燃料电池阴极浓度过电压 Fick模型传质

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染料敏化分解水制氢技术进展

电源技术 2006年第10期30卷 856-859页

作者：倪萌 LEUNG MIcHAEL K H LEUNG dennis Y c 香港大学机械工程系

介绍了染料敏化分解水制氢的基本原理。综述了染料分子的选取,使用氧化还原调节剂的机理和研究进展。指出染料分子对光谱的吸收特性,激发态染料分子能级与半导体导带的相对位置,染料分子与半导体的吸附情况,表面键合强度直接影响对光子... 详细信息

介绍了染料敏化分解水制氢的基本原理。综述了染料分子的选取,使用氧化还原调节剂的机理和研究进展。指出染料分子对光谱的吸收特性,激发态染料分子能级与半导体导带的相对位置,染料分子与半导体的吸附情况,表面键合强度直接影响对光子的吸收,电子的注入,从而影响产氢量。此外,I-/I3-作为氧化还原调节剂可有效还原染料分子,实现持续产氢。最后提出了染料敏化分解水制氢的间歇式反应器结构,以及通过选择用于敏化的半导体来提高产氢率的思路。

关键词：染料敏化制氢光催化可再生能源

Stable carbon Isotope Discrimination (δ¹³c) of cotton Burrs and Seeds as a Season-Long Integrator of crop Water Stress

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American Journal of Plant Sciences 2022年第12期13卷 1448-1459页

作者： dennis c. Gitz III Jeffrey T. Baker Robert J. Lascano cropping Systems Research Laboratory ARS-USDA1 Lubbock USA

Plant-based irrigation management schemes typically use surrogates such as canopy temperature, alone, or in conjunction with environmental variables, to infer the degree of “crop stress” (biological strain) induced by drought. Few systematic studies of the relationship between “crop stress”, as defined by such surrogates, and physiological estimates of water use efficiency (WUE) exist over both daily and seasonal time scales relevant to agronomic irrigation control. The systematic application of stable carbon isotope discrimination (δ13c) might allow post hoc evaluation of irrigation scheduling schemes and might also be a useful germplasm screening tool if the source(s) of variability can be uncovered and/or controlled. Results from preliminary efforts comparing leaf and cotton seed δ13c to season-long water deficits showed that seeds are more useful indicators of season-long water stress and water use efficiency during crop development.

关键词： Irrigation-Scheduling Germplasm Screen Water Management

Scaling Leaf Measurements to Estimate Whole canopy Gas Exchanges of cotton

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American Journal of Plant Sciences 2016年第14期7卷 1952-1963页

作者： dennis c. Gitz III Jeffrey T. Baker Robert J. Lascano Wind Erosion and Water conservation Unit Cropping Systems Research Laboratory USDA-ARS1 Lubbock TX USA

Diurnal leaf and canopy gas exchanges of well-watered field grown cotton were measured. Our objective was to scale leaf-level values of transpiration and net assimilation to the whole canopy level using estimates of canopy leaf area. Single leaf gas exchange measurements were made with two portable photosynthesis systems and canopy measurements with four open canopy Evapo-Transpiration and Assimilation (cETA) chamber systems. canopy leaf area was measured at the end of the experiment and estimated during gas exchange by fitting values to a growth curve. Leaf level measurements were arithmetically scaled to estimate canopy level gas exchange based on canopy leaf area and then compared to the measured values. Scaled values of single leaf transpiration were very similar to canopy transpiration measurements, although both whole canopy transpiration and assimilation were overestimated around mid-day. We conclude that canopy cotton transpiration of well-watered field grown plants could be estimated within 5% throughout the day by scaling leaf level measurements to the whole canopy using measured canopy leaf area. Estimating canopy assimilation from leaf level measurements remains problematic.

关键词： cotton Gossypium hirsutum Scaling Assimilation Transpiration Drought Stress

Radiation-induced oral mucositis hamster model using a linear accelerator enhances clinical relevance of preclinical studies for treatment strategy investigation

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Animal Models and Experimental Medicine 2021年第1期4卷 47-53页

作者： carolyn T.Jordan Emily M.Bradford dennis c.cheek Mahesh Kudrimoti craig S.Miller Molly H.Smith J.Zach Hilt Thomas D.Dziubla Department of chemical and Materials Engineering University of KentuckyLexingtonKYUSA Department of Internal Medicine University of KentuckyLexingtonKYUSA Department of Radiation Medicine University of KentuckyLexingtonKYUSA Department of Oral Health Practice University of KentuckyLexingtonKYUSA Department of Oral and Maxillofacial Pathology University of KentuckyLexingtonKYUSA

Translational animal models for oral mucositis(OM)are necessary to simulate and assess the bioclinical effects and response in *** models should simulate high levels of radiation exposure that leads to oxidative stress and inflammatoryinitiated tissue *** models have been extensively studied to observe pathological effects of radiation exposure and help in the development of effective *** successfully evaluate the potential for treatment regimens with consistency and relevance,a radiation-induced OM hamster model was developed using a clinical linear accelerator utilized by cancer patients *** dose exposure to the isolated,everted cheek pouch of a hamster,as well as the progression of injury,proinflammatory marker,histological,and elasticity analyses of the buccal pouch were conducted to verify replicability and reproducibility of the injury *** findings from this model demonstrated its ability to consistently induce injury and resolution over 28 days using an acute dose of 60 *** model was developed to enhance clinical relevance when evaluating potential efficacious treatments and can now be utilized in efficacy studies to better evaluate developed therapeutics in a preclinical model that is easy to translate to clinical studies..

关键词： animal models radiotherapy stomatitis

Relating Xylem cavitation to Gas Exchange in cotton

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American Journal of Plant Sciences 2015年第11期6卷 1742-1751页

作者： dennis c. Gitz III Jeffrey T. Baker Robert J. Lascano cropping Systems Research Laboratory USDA-ARS# Lubbock USA

Acoustic emissions (AEs) from xylem cavitation events are characteristic of transpiration processes. Though a body of work exists describing AEs and limited stem hydraulic conductivity under water stress, there is limited information about the effects of AEs on stomatal aperture and limitation on carbon assimilation. The objective of this work was to relate AEs to drought stress in cotton. cotton was grown in mini-lysimeters in the greenhouse and instrumented with a portable photosynthesis system and ultrasonic transducers connected to a digital signal-processing unit. Whole plant transpiration, leaf level gas exchange and ultrasonic AEs were measured. Xylem cavitation events temporally associated with the onset of drought stress. The results are consistent with stomatal closure in response to reduced hydraulic conductance from xylem cavitation events. clear direct empirical evidence of a reduction in carbon assimilation associated with xylem cavitation resulting from water stress is presented.

关键词： Xylem cavitation Drought Stress Stomatal control Irrigation Scheduling

Evaluation of a Metabolic cotton Seedling Emergence Model

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American Journal of Plant Sciences 2015年第11期6卷 1727-1733页

作者： dennis c. Gitz III Jeffrey T. Baker James R. Mahan cropping Systems Research Laboratory United States Department of Agriculture* Lubbock USA

A model for cotton seedling emergence (MaGi) based on malate synthase kinetics was evaluated. cotton seeds were planted through the early spring and into typical planting times for the areas. Soil temperatures at seed depth were used as inputs into MaGi and a commonly used seedling emergence model based on heat unit accumulation (DD60). Time to 50% emergence was calculated and compared with predicted emergence using MaGi and DD60. MaGi yielded predictive capability without the need to resort to lengthy experimentation required by traditional methods. The results suggest that a physiological or semi-empirical approach incorporating both enzyme kinetics and whole plant temperature responses would be useful for rapidly constructing seedling emergence models.

关键词： cotton Seed Emergence Degree Day crop Model

Effect of Ambient UV-B on Stomatal Density, conductance and Isotope Discrimination in Four Field Grown Soybean [<i>Glycine max</i>(L.) Merr.] Isolines

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American Journal of Plant Sciences 2013年第12期4卷 100-108页

作者： dennis c. Gitz III Steven J. Britz Joseph H. Sullivan Department of PLSA College of Agriculture and Natural Resources University of Maryland College Park USA USDA-ARS# Cropping Systems Research Laboratory Lubbock USA USDA-ARS Food Components and Health Laboratory Beltsville USA

An experiment was designed to test whether ambient levels of UV-B radiation affect stomatal development, decrease stomatal density, and lead to increased water-use efficiency (WUE). Soybean [Glycine max (L.) Merr.] isolines with different stomatal distribution and flavonol expression patterns were field grown under shelters that either transmitted or blocked solar UV-B. All isolines exposed to solar UV-B accumulated higher concentrations of UV-screening phenolic pigments but other responses were isoline dependent. Solar UV-B decreased stomatal density and conductance in isolines expressing a unique branched kaempferol triglycoside. Decreased stomatal density was associated with increased season-long WUE and decreased internal cO2 concentration of leaf (estimated by δ13c discrimination). We concluded that photomorphogenic responses to UV-B affected stomatal density and WUE in field grown soybean;but that the magnitude and direction of these response were associated with isogenic pleiotropic differences in stomatal distribution and pigment expression. UV-B radiation had no effect on biomass accumulation or yield in a cultivar expressing only trace levels of kaempferol suggesting that flavonol expression is not prerequisite to UV-B tolerance.

关键词： Soybean UV-B Drought Stress Water Use Efficiency Isotope Discrimination Photomorphogenesis