Direct measurement of oxygen consumption rates from attached and unattached cells in a reversibly sealed, diffusionally isolated sample chamber

Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unattached biological samples without compensation for extraneous oxygen leaking into the system. Here we present the Respiratory Detection System, which is compatible with virtually any biological sample. The RDS can be used to measure oxygen uptake in microliter-scale volumes with a reversibly sealed sample chamber, which contains a porphyrin-based oxygen sensor. With the RDS, one can maintain a diffusional seal for up to three hours, allowing for the direct measurement of respiratory function of samples with fast or slow metabolic rates. The ability to easily measure oxygen uptake in small volumes with small populations or dilute samples has implications in cell biology, environmental biology, and clinical diagnostics.

A Three-Dimensional Model of Transport and Diffusion of Seeding Agents within Stratus

It is essential to learn the temporal and spatial concentration distributions and variations of seeding agents in cloud seeding of precipitation enhancement. A three-dimensional puff trajectory model incorporating a mesoscale nonhydrostatic model has been formulated, and is applied to simulating the transporting and diffusive characteristics of multiple line sources of seeding agents within super-cooled stratus. Several important factors are taken into consideration that affect the diffusion of seeding materials such as effects of topography and vertical wind shear, temporal and spatial variation of seeding parameters and wet deposition. The particles of seeding agents are assumed to be almost inert, they have no interaction with the particles of the cloud or precipitation except that they are washed out by precipitation. The model validity is demonstrated by the analyses and comparisons of model results, and checked by the sensitivity experiments of diffusive coefficients and atmospheric stratification. The advantage of this model includes not only its exact reflection of heterogeneity and unsteadiness of background fields, but also its good simulation of transport and diffusion of multiple line sources. The horizontal diffusion rate and the horizontal transport distance have been proposed that they usually were difficult to obtain in other models. In this simulation the horizontal diffusion rate is 0.82 m s(-1) for average of one hour, and the horizontal average transport distance reaches 65 km after 1 4 which are closely related to the background Fields.

Diffusion of Acetic Acid Across Oil/Water Interface in Emulsification-Internal Gelation Process for Preparation of Alginate Gel Beads

Alginate has been widely used in cell microencapsulation and drug delivery systems in the form of gel beads or microcapsules.Although an alternative novel emulsification-internal gelation technology has been established and both the properties and the potential applications of the beads in drug delivery systems have been studied,the mechanism has not been well understood compared with the traditional droplet method（external gelation technology）.On the basis of our previous knowledge that the novel technology is composed of complicatedly consecutive processes with multistep diffusion and reaction,and the diffusion of acetic acid across oil/water interface being the prerequisite that determines the occurrence and rate for the reactions and the structures and properties of final produced gel beads,a special emphasis was placed on the diffusion process.With the aid of diffusion modeling and simple experimental design,the diffusion rate constant and diffusion coefficient of acetic acid across oil/water interface were determined to be in the orders of magnitude of 10-6 and 10-16,respectively.This knowledge will be of particular importance in understanding and interpreting the formation,structure of the gel beads and the relationship between the structure and properties and guiding the preparation and quality control of the gel beads.

片层状贝氏体铁素体长大动力学研究

为研究合金元素含量对钢中贝氏体铁素体长大动力学的影响,采用Zener-Hillert和Bosze-Trivedi动力学模型,通过选取热力学和动力学参数,计算了合金成分不同的钢的片层状贝氏体铁素体长大速度.研究表明:Fe-0.59C、Fe-0.81C和Fe-0.478C-4.87Ni合金在贝氏体相变时,贝氏体铁素体长大速度可以用无分配局部平衡条件下的扩散模型很好地描述,Fe-0.69C-1.8Ni-0.8Mo合金贝氏体铁素体长大速度略慢于理论值,Fe-C-8.7Ni合金贝氏体铁素体的长大速度比理论值约慢2个数量级;合金元素含量高的钢的贝氏体铁素体长大速度无法用扩散控制模型很好地描述;结合对贝氏体相变机制的讨论,提出贝氏体相变机制可能与相变温度和钢的成分相关.

砂仁光合作用的CO_2扩散限制与气孔限制分析

目前常用从气体交换参数计算的胞间CO2 浓度(Ci)来计算气孔限制值(Ls),但由于胁迫情况下计算的Ci偏高常导致结果不准确。该文引入扩散限制分析概念,以砂仁为例介绍了一种不需Ci 的计算扩散限制值(Ld)的新方法。同时通过叶绿素荧光参数间接估算受干旱胁迫植株的Ci(用Ci′表示)计算气孔限制值(Ls′)。采用这3种方法分析了生长在100%和40%土壤相对湿度(RSM)下的砂仁(Amomum villosum)净光合速率的限制因素。结果表明两种水分状况下砂仁午后净光合速率的限制因素不同。100%RSM下,午后砂仁Ls 没有升高,说明光合作用气孔限制并未增强;午后其Ld 升高表明光合作用的CO2 扩散限制增强,这主要是由叶肉阻力相对增大所致。40%RSM下,午后砂仁Ls′升高比Ld 升高明显,说明气孔阻力在所有扩散阻力中占主导作用,是限制净光合速率的主要原因;而其Ls 午后并未升高,暗示传统的气孔限制分析会得出非气孔限制的错误结论。Ci′低于Ci,说明干旱胁迫时传统的气体交换方法高估了Ci。上述结果都证明水分胁迫情况下传统方法不可靠,该文介绍的两种新方法比较准确可靠,同时使用两种新方法还可定性推测叶肉阻力的变化方向。

Kinetic Factors for Intensive Reaction of Magnesium-Based Spheroidiser in Hot Metal

The spheroidiser is a necessary additive to manufacture ductile iron.Sometimes with the same hot metal,spheroidisers and treated technology,reactions differ greatly from each other.The reaction may be quite normal in one case,but very intensive for another one.The effects of kinetic factors such as size,surface area and morphology o f spheroidiser on the reaction of spheoidization are studied.

Effect of molecular weight on the quality of poly(alpha-methylstyrene) mandrel

Hollow poly(alpha-methylstyrene)(PAMS)shows application in inertial confinement fusion experiments as the degradable mandrels of glow plasma polymer shells.However,the molecular weight of PAMS has great influence on the quality of mandrels.In this work,this influence was systematically studied using several PAMS samples with different molecular weights.For PAMS shells with 900 mm inner diameter and different wall thickness,when the molecular weight of PAMS is in the range of 300e500 kg·mol^(-1),perfect sphericity and good wall thickness uniformity can be obtained.In contrast,when increasing molecular weight to 800 kg·mol^(-1),the sphericity and the wall thickness uniformity become worse.Moreover,compared with the wall uniformity,the sphericity of PAMS shells was much less sensitive to the molecular weight.The results also showed that the stability of W1/O compound droplets of PAMS shells were less affected by the molecular weight.It was revealed that the wall uniformity and the sphericity of the PAMS shells were associated with the diffusion rates of fluorobenzene(FB).

An Optimized Parameter of Hydrogel for a Seven-Day Release of a Drug

Drug release is a crucial process in treatment. Conventional drug administration requires patient’s compliance and has the risk of overdosing. In order to control drug release, several potential materials are develo0ped. In this paper, we focus on hydrogel material and simulate drug release process in MATLAB. We optimize the parameter for a seven-day release of a drug. The results show that the diffusion coefficient at approximately 4.00E−11 could ensure medicine to diffuse around 7 days and maintain its effects.

强磁场下冷却速度对Fe-0.12%C合金显微组织的影响

研究了强磁场(12T)下冷却速度对Fe-0.12%C合金中的珠光体组织形貌的影响.结果表明:强磁场下珠光体团的长轴方向与磁场方向平行且伸长的程度随其冷却速度的提高而减弱.板平面平行于磁场方向比垂直于磁场方向放置的试样的珠光体面积分数低,同时珠光体团长轴方向与磁场方向平行且伸长的程度也低.最后,探讨了强磁场下珠光体组织形貌的演变机理.

扩散沉积导致的管内气溶胶穿透率简明公式

针对气溶胶粒子在长直扁平方管(通道)及圆管内受布朗扩散导致的沉积损失问题,从对流扩散方程出发,采用分离变量法,通过严格的理论求解得到了这两类问题中粒子穿透率的无穷级数解。利用Python语言中高精度计算功能确定了相应本征问题的本征值、本征函数及无穷级数展开系数。根据所得的相对严格意义上的穿透率数据,回归拟合得到了扩散沉积条件下粒子通过方管及圆管时的穿透率简明公式,并与已有研究进行了详细的比较。结果表明:本文得到的两个简明公式更加简单和准确,对方管与圆管内粒子穿透率估计的误差最大值分别仅为3.7×10^(-4)和8.3×10^(-4),可以快速有效地估计层流条件下和受扩散沉积作用时,气溶胶粒子通过两种管(通)道的穿透率。

The Accumulation of He on a W Surface During keV-He Irradiation:Cluster Dynamics Modeling

The accumulation of He on a W surface during keV-He ion irradiation has been simulated using cluster dynamics modeling. This is based mainly on rate theory and improved by involving different types of objects, adopting up-to-date parameters and complex reaction processes, as well as considering the diffusion process along with depth. These new features make the simulated results compare very well with the experimental ones. The accumulation and diffusion processes are analyzed, and the depth and size dependence of the He concentrations contributed by different types of He clusters is also discussed. The exploration of the trapping and diffusion effects of the He atoms is helpful in understanding the evolution of the damages in the near-surface of plasma-facing materials under He ion irradiation.

Turbulent mixing in the upper ocean of the northwestern Weddell Sea, Antarctica

Turbulent mixing in the upper ocean（30-200 m） of the northwestern Weddell Sea is investigated based on profiles of temperature,salinity and microstructure data obtained during February 2014.Vertical thermohaline structures are distinct due to geographic features and sea ice distribution,resulting in that turbulent dissipation rates（ε） and turbulent diffusivity（K） are vertically and spatially non-uniform.On the shelf north of Antarctic Peninsula and Philip Ridge,with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m,both ε and K show significantly enhanced values in the order of O（10^（-7））-O（10^（-6）） W/kg and O（10^（-3））-O（10^（-2）） m^2/s respectively,about two or three orders of magnitude higher than those in the open ocean.Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau,where s decreases with depth from O（10^（-8）） to O（10^（-9）） W/kg,while K changes vertically in an inverse direction relative to s from O（10^（-6）） to O（10^（-5）） m^2/s.In the marginal ice zone,K is vertically stable with the order of10^（-4） m^2/s although both intense dissipation and strong stratification occur at depth of 50-100 m below a cold freshened mixed layer.Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions,our results indicate weak relationship between K and wind stress or tidal kinetic energy.Instead,intensified mixing occurs with large bottom roughness,demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing.In addition,geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing.

Ergodicity of Reversible Reaction Diffusion Processes with General Reaction Rates

In this paper,a class of reaction diffusion processes with general reaction rates is studied.A necessary and sufficient condition for the reversibility of this calss of reaction diffusion processes is given,and then the ergodicity of these processes is proved.

建筑物缝隙内气溶胶穿透率的严格估计与分析

严格求解了气溶胶粒子通过建筑围护结构缝隙时的动力学方程,给出了受重力沉降与扩散共同影响的粒子穿透率解析解,并与已有文献中穿透率实测、理论模型、三种常用近似计算方法(乘积耦合、方根耦合、加法耦合)的结果进行了详细比较。结果表明:解析解可直接估计粒子随渗风气流通过建筑结构缝隙时受扩散与重力共同作用时的穿透率;采用三种穿透率耦合法估计粒径大约为0.1mm^1mm的粒子的穿透率时,会存在差异,三者间的差别随缝隙高度降低,随缝隙变长、缝隙两侧压差减小而逐渐增加。对于极小的缝隙,已有的三种耦合方法均明显低估了粒子穿透率,与精确值相比,最大相差达50%。结果同时证明:当缝隙高度低于0.5mm时,使用简单的乘积耦合和加法耦合方法对粒子穿透率估计并不准确;当缝隙高度大于0.14mm时,采用方根耦合方法估计得到的粒子穿透率与本文得到的精确值吻合。

INFLUENCE OF GEOMETRICAL CONFIGURATION OFSUPERCONDUCTING MATERIAL ON GROWTH OF Nb_3 Sn

Boundary conditions constructed by two typical geometrical configurations related to the manufacturing methods of bronze process and tin-rich Nb tube method have been considered in a diffusion model in which the diffusion of Sn in CuSn matrix plays a major role is as- sumed.The dependence of thickness of Nb_3Sn layer on reaction time has been derived.It is shown that the growth rate of Nb_3Sn relates to the configuration of the superconductor,the geometrical parameters of Nb filaments and CuSn matrix.The theory is qualitatively con- sistent with the experimental results.

Prediction and validation of diffusive uptake rates for indoor volatile organic compounds in axial passive samplers

The diffusive uptake rate is essential for using passive samplers to measure indoor volatile organic compounds(VOCs).The traditional theoretical model of passive samplers requires available regression formulas of uptake rates and physicochemical properties of adsorbents to predict the uptake rate.However,it is difficult to obtain the uptake rates of different VOCs under different sampling periods,and it is also difficult to obtain the physical parameters of adsorbents accurately and effectively.This study provides a reliable numerical prediction method of diffusive uptake rates of VOCs.The modeling was based on the standard automated thermal desorption(ATD)tubes packed with Tenax TA and the mass transfer process during adsorption.The experimental determinations of toluene uptake rate are carried out to verify the prediction model.Diffusive uptake rates of typical indoor VOCs are obtained from the literature to calibrate the key apparent parameters in the model by statistical regression fitting.The predicted model can provide the VOC diffusive uptake rates under different sampling duration with an average deviation of less than 5%.This study can provide the basis for fast and accurate prediction of diffusive uptake rates for various VOC pollutants in built environments.

THE DIFFUSION PARAMETER AND HEAT-RELEASE RATE OF PLUMES CAUSED BY THE 1987 FOREST FIRE IN NORTHEAST CHINA

In this paper the meteorological background for the formation of plume from the forest fire in Northeast China on 7—8 May 1987 is stated.The long-range instantaneous diffusion parameters are calculated by using the satellite photograph of the plumes with visible length ranging from 100 to over 500 kin.The results of cal- culation show that the relations between instantaneous diffusion parameter and travel time(up to 60000 sec.) obey the law of linear or 3/2 power.In addition,heat release from the fire on May 7—8 estimated by puff rising formula can meet,in respect to the order of magnitude,the value gained on the field survey.

Microstructural stability and aging behavior of refractory high entropy alloys at intermediate temperatures

Several body-centered-cubic(BCC)refractory high entropy alloys(HEAs),i.e.,Hf Nb Ta Ti Zr,Nb Ta Ti Zr,Hf Nb Ti Zr and Nb Ti Zr,were annealed at intermediate temperatures for 100 h,and their microstructures and aging behaviors were studied in detail.All these HEAs start to decompose into multiple phases at around 500°C,but reenter the single-phase region at significantly different temperatures which were determined to be 900,1000,1100 and above 1300°C for Hf Nb Ti Zr,Nb Ti Zr,Hf Nb Ta Ti Zr and Nb Ta Ti Zr,respectively.Our analysis indicates that the onset decomposition temperature in these four HEAs is closely related to the elemental diffusion rates while the ending decomposition temperature is strongly dependent on the elemental melting points.Our findings are important not only for understanding phase stability of HEAs in general,but also for adjusting processing parameters to optimize mechanical properties of these HEAs.

Soil Aeration Variability as Affected by Reoxidation

The interplay between soil physical parameters during the recovery from anoxic stresses （reoxidation） is largely unrecognized. This study was conducted to chaxacterise the soil aeration status and derive correlations between variable aeration factors during reoxidation. Surface layers （0-30 cm） of three soil types, Haplic Phaeozem, Mollic Gleysol, and Eutric Cambisol （FAO soil group）, were selected for analysis. The moisture content was determined for a range of pF values （0, 1.5, 2.2, 2.7, and 3.2）, corresponding to the available water for microorganisms and plant roots. The variability of a number of soil aeration parameters, such as water potential （pF）, air-filled porosity （Eg）, oxygen diffusion rate （ODR）, and redox potential （Eh）, were investigated. These parameters were found to be interrelated in most cases. There were significant （P 〈 0.001） negative correlations of pF, Eg, and ODR with Eh. A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment. These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.

Li_(4)Ti_(5)O_(12)spinel anode:Fundamentals and advances in rechargeable batteries

The Li_(4)Ti_(5)O_(12)(LTO)spinel material,ranking at the second large market share after graphite,is a promising anode material for lithium-ion batteries due to its good cycle stability,rate capability,and safety with both conventional and low-temperature electrolytes.However,several critical challenges,such as the low capacity and gassing issue,hindered the wide applications of LTO anode.Recent progress indicated that the LTO performances are possible to be further improved by novel strategies,such as heterogeneous phase control,surface engineering,or overlithiation.To rethink and develop advanced LTO anodes,this review intensively associates the performances and modification strategies with the electronics/crystal structures.From a thermodynamic/kinetic point of view,we summarized the data obtained from recently developed characterization techniques,and the results of electrochemical performances and fundamental structures of LTO to potentially address several key challenges and issues toward advanced LTO anodes.As a result,light is shed on the future research direction of the LTO anodes.