Effect of Size and Initial Water Content on the Effective Diffusion Coefficient during Convective Drying of Sweet Potato Cut into Cubic and Cylindrical Shapes

In this article, we investigated the influence of size and initial water content on the effective diffusion coefficient of sweet potatoes samples cut into cubic and cylindrical shapes. The sizes of the cubic samples are 0.5, 1, 1.5, 1.75, 2, 2.5 and 3 cm edge with a respective initial water content of 2.7, 3.76, 3.48, 2.68, 3.28, 2.17 and 2.29 kg/kgms. For cylindrical samples, the radius is set at 0.5 cm and sample heights are 1, 1.5, 2, 2.5, 3, 3.5 and 4 cm with respective water contents of 2.2, 3.19, 2.85, 2.1, 2.17, 2.39 and 2.03 kg/kgms. The effective diffusion coefficients of cubic samples are of the order of 10−10 and 10−9 m2∙s−1 grew with sample edge. As for the cylindrical samples, the effective diffusion coefficients were of the order of 10−9 m2∙s−1 and there was no linear correlation between cylinder height and their effective diffusion coefficient. As for the examination of the initial water content on the effective diffusion coefficient, it turned out that the initial water content had no influence on the effective diffusion coefficient of the sweet potato samples.

Research on Policy Diffusion Path and Reproduction of River Chief System

The River Chief System (RCS) has evolved from local innovative practices to a national water governance strategy to address the current challenges in China’s water environmental management. In contrast to existing research that focuses on the strengths, weaknesses, and improvements of RCS, this study uses literature study to reveal the dynamic evolution of RCS through three phases, with RCS spreading from developed coastal areas to central and western inland regions. RCS’s diffusion path involves vertical diffusion between central and local levels and horizontal diffusion among local governments. Moreover, RCS has also achieved conceptual spillover, gradually expanding into other governance domains, such as the Lake Chief System, the Field Chief System, the Forestry Chief System, and the integration of multiple chief roles. However, it is essential to scrutinize the phenomenon of applying similar governance mechanisms to different areas, as it may result in challenges such as overburdening local governments, insufficient public participation, oversimplification of differences in natural resource endowments, and limited applicability. This study also provides suggestions on how to address these challenges. The study contributes theoretical insights and policy implications, providing a foundation for practical policy innovation.

The Impact and Intervention of Handheld Tai Chi Water-Resistance Fitness Ball on Middle-Aged and Elderly Patients with Parkinson’s Disease

Through the use of a survey and statistical methods, this study explores the effects and interventions of handheld Tai Chi water resistance fitness balls on the elderly with Parkinson’s disease. Firstly, a questionnaire on exercise compliance for patients with Parkinson’s disease was developed, and its reliability and validity were tested. Then, a survey was conducted to investigate the current status of exercise compliance among Parkinson’s disease patients, including general information, scoring status, and single and multiple factor analyses of influencing factors [1]. The results of the study show that through qualitative research, the dimensions and item pools of the questionnaire were initially constructed, and the reliability analysis of the questionnaire was conducted through Delphi expert consultation, with favorable results in terms of its reliability and validity [2]. Regarding the current status of exercise compliance among Parkinson’s disease patients, the study found that the level of exercise compliance needs improvement, and there are significant differences in exercise compliance levels among patients under different circumstances. Finally, the research results were discussed and conclusions were drawn. The innovation of this study lies in the development of a questionnaire on exercise compliance for patients with Parkinson’s disease and the preliminary qualitative research and Delphi expert consultation conducted on it, providing new ideas and methods for the study of exercise compliance. However, the study also has limitations as it did not examine the effects of other interventions on Parkinson’s disease, so further research should be conducted [3].

基于B/S和SOA架构的LIMS系统设计与研究

为提升水质检测业务的专业化、智能化、系统化、自动化水平,针对新发展阶段下水利高质量发展对水质信息管理的需求,研究并开发基于B/S系统架构和SOA设计架构的新型综合性水质信息管理系统(LIMS),运用仪器谱图识别及数据提取、PHP与MySQL融合、仪器谱图与原始记录自动关联等技术,在一定程度上提高水质数据的电子化无纸化获取、处理、传输及应用等方面的管理水平,实现水质检测业务流程与资源的动态关联和闭环追溯,提升水质监测评价工作的管理效率和质量管理能力。基于B/S和SOA架构的LIMS在前沿高新技术中的应用研究,为水质检测和管理的各项活动提供智能、高效的数据支持平台,也为水利行业信息系统管理建设及水域功能监测监管提供技术支撑。

Experimental Study on the Influence of Fracturing Fluid Retention on Shale Gas Diffusion Law

Shale gas reservoirs have poor physical properties and a large number of micro-nano pores have been developed.Shale gas wells have no natural productivity and need fracturing reconstruction measures to put into production.However,the fracturing fluid will enter the reservoir space of shale matrix after fracturing and affect the production of shale gas.At present,there is no consensus on the influence of fracturing fluid retention on gas well production.Based on this,the paper adopts gas molecular transport analyzer to carry out experimental research on the influence of fracturing fluid on shale gas diffusion law after entering matrix pores.The results show that:(1)Compared with the diffusion capacity of single-phase shale gas,the diffusion capacity of shale gas decreases significantly when fracturing fluid is present in the reservoir;(2)In the process of fracturing fluid flowback,when the water saturation in the reservoir decreases from 50%to 0,the gas well productivity increases by about 60%.(3)When fracturing fluid exists in the reservoir,the pore diameter has an exponential relationship with the shale gas diffusion coefficient,and the diffusion coefficient increases exponentially with the increase of pore diameter.The research of this paper provides theoretical basis for guiding the efficient development of shale gas wells.

An improved ion-exchange/diffusion method for ～(15)N isotope tracing analysis of nitrate in surface waters from watersheds

An improved method,suitable for collecting nitrate from surface waters in the watershed for 15 N isotope tracing analysis,was developed on the basis of the anion exchange coupled with diffusion through systematic simulation and comparison experiments.The results showed that the nitrate could be separated and enriched from the waters efficiently by using the improved method.Being simple and practical in operation principle and procedures,cost-economic,and highly efficient in nitrate separation/enrichment,the method met the requirements of δ 15 N mass spectrum analysis and would lay a foundation for the application of 15 N isotope tracing approach to the research on non-point source pollution in watershed.

Molecular dynamics simulations of CH4 diffusion in kaolinite: influence of water content

Understanding the interaction of CH4 with kaolinite is significant for researchers in the fields of coalbed CH4 and shale gas.The diffusion behaviors of CH4 in kaolinite with water contents ranging from 0 to 5 wt% have been analyzed by molecular dynamics simulations.The results of the simulations indicate that CH4 molecules can jump between adjacent holes in the kaolinite matrix.CH4 diffusion coefficient was very low (3.28 × 10-9 m2/s) and increased linearly with the increasing of water content.As the water content decreased,the value of radial distribution function first peak between CH4 and oxygen was larger,meaning that with lower water content,the interaction energy between CH4 and oxygen in kaolinite is stronger.The interaction between CH4 and water is linearly positively correlated with water content,in contrast,the interaction energy between kaolinite and water as well as between kaolinite and CH4 decreased linearly with increasing water content.On the other hand,the diffusion of CH4 molecules adsorbed on the surfaces also can be accelerated by the fast diffusion of water molecules in the middle micropore of the kaolinite.

Laboratory investigation into the oil diffusion from submarine pipeline under water flow

A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow.The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The oil trajectory, velocity and the rising time to the surface are obtained through this system. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled discharge is the primary factor affecting the rising time of the oil particles. In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity. The study can provide a theoretical reference for the prediction system of oil spill emergency.

Understanding self-accelerated water diffusion within poly-lactic acid via molecular dynamics simulation

Poly-lactic acid(PLA) is widely used as a controlled drug release material and the diffusion property of water within the polymer matrix is closely related to the drug release profile. This paper studies the water diffusion in PLA by molecular dynamic simulations. Free volume analysis indicates that water molecules are expected to fill in the free volumes of the polymer matrix forming water clusters at low water content. Along with the increase of the water concentration, the polymer starts to swell and the density of the system starts to drop.Due to the high mobility of water within water cluster, the calculated diffusion coefficient dramatically increases along with the incensement of water content. Thus, we conclude that the diffusion of water is a self-accelerate process, with higher mobility of water in the case where more water exists.

Water molecules and oxygen-vacancy modulation of vanadium pentoxide with fast kinetics toward ultrahigh power density and durable flexible all-solid-state zinc ion battery

Aqueous zinc ion battery(ZIB)with many virtues such as high safety,cost-effective,and good environmental compatibility is a large-scale energy storage technology with great application potential.Nevertheless,its application is severely hindered by the slow diffusion of zinc ions in desirable cathode materials.Herein,a technique of water-incorporation coupled with oxygen-vacancy modulation is exploited to improve the zinc ions diffusion kinetics in vanadium pentoxide(V_(2)O_5)cathode for ZIB.The incorporated water molecules replace lattice oxygen in V_(2)O_5,and function as pillars to expand interlayer distance.So the structural stability can be enhanced,and the zinc ions diffusion kinetics might also be promoted during the repeated intercalation/deintercalation.Meanwhile,the lattice water molecules can effectively enhance conductivity due to the electronic density modulation effect.Consequently,the modulated V_(2)O_5(H-V_(2)O_5)cathode behaves with superior rate capacity and stable durability,achieving 234 mA h g^(-1)over 9000 cycles even at 20 A g^(-1).Furthermore,a flexible all-solid-state(ASS)ZIB has been constructed,exhibiting an admirable energy density of 196.6 Wh kg^(-1)and impressive power density of 20.4 kW kg^(-1)as well as excellent long-term lifespan.Importantly,the assembled flexible ASS ZIB would be able to work in a large temperature span(from-20 to 70℃).Additionally,we also uncover the energy storage mechanism of the H-V_(2)O_5 electrode,offering a novel approach for creating high-kinetics cathodes for multivalent ion storage.

Tracing surface seawater mixing and nutrient transport by^(222)Rn on the northern coast of Beibu Gulf,China

The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion process of water indicates the possible transport direction of dissolved substances.However,the complex environment in the coastal zone makes it difficult to quantitatively assess the water diffusion process.^(222)Rn is a useful tool to trace the diffusion process of water bodies.However,studies on the^(222)Rn distribution and its behavior in the Beibu Gulf are scarce.In this study,the activity distribution characteristics of^(222)Rn in surface seawater of the Guangxi shelf area of the Beibu Gulf were measured.Based on the one-dimensional,steady-state model,the vorticity diffusion coefficient of^(222)Rn in the horizontal direction was calculated as(0.42−2.13)×10^(8) m^(2)/d,and the offshore fluxes of^(222)Rn under the influence of water mixing were calculated as 2.00×10^(12) Bq/d.Correspondingly,the horizontal transport fluxes of silicate,phosphate,nitrite and nitrate were 6.28×10^(−3)mol/(m^(2)·d),0.10×10^(−3)mol/(m^(2)·d),0.20×10^(−3)mol/(m^(2)·d)and 4.15×10^(−3)mol/(m^(2)·d),respectively.These results indicate that the study of eddy current diffusion in offshore marine water facilitates a deeper understanding of the water mixing process and nutrient transport and migration.

On the sampling strategies and models for measuring diffusion exchange with a double diffusion encoding sequence

Water exchange between the different compartments of a heterogeneous specimen can be characterized via diffusion magnetic resonance imaging(dMRI).Many analysis frameworks using dMRI data have been proposed to describe exchange,often using a double diffusion encoding(DDE)stimulated echo sequence.Techniques such as diffusion exchange weighted imaging(DEWI)and the filter exchange and rapid exchange models,use a specific subset of the full space DDE signal.In this work,a general representation of the DDE signal was employed with different sampling schemes(namely constant b1,diagonal and anti-diagonal)from the data reduction models to estimate exchange.A near-uniform sampling scheme was proposed and compared with the other sampling schemes.The filter exchange and rapid exchange models were also applied to estimate exchange with their own subsampling schemes.These subsampling schemes and models were compared on both simulated data and experimental data acquired with a benchtop MR scanner.In synthetic data,the diagonal and near-uniform sampling schemes performed the best due to the consistency of their estimates with the ground truth.In experimental data,the shifted diagonal and near-uniform sampling schemes outperformed the others,yielding the most consistent estimates with the full space estimation.The results suggest the feasibility of measuring exchange using a general representation of the DDE signal along with variable sampling schemes.In future studies,algorithms could be further developed for the optimization of sampling schemes,as well as incorporating additional properties,such as geometry and diffusion anisotropy,into exchange frameworks.

Cu_(3)Mo_(2)O_(9)/Mn_(0.3)Cd_(0.7)S S型异质结的构筑及其光解水产氢性能研究

采用超声辅助研磨煅烧法制备了Cu_(3)Mo_(2)O_(9)/Mn_(0.3)Cd_(0.7)S S型异质结光催化剂,通过X射线粉末衍射仪、扫描电子显微镜、X射线光电子能谱、固体紫外漫反射等测试技术表征了样品的物相、形貌、化学元素组成以及光吸收能力等物理化学性质。在可见光加近红外光照射下进行了光催化析氢性能测试,结果表明,Cu_(3)Mo_(2)O_(9)/Mn_(0.3)Cd_(0.7)S复合材料的光解水产氢性能均优于纯相的Mn_(0.3)Cd_(0.7)S和Cu_(3)Mo_(2)O_(9),其中Cu 3Mo 2O 9的质量分数为1%的Cu_(3)Mo_(2)O_(9)/Mn_(0.3)Cd_(0.7)S显示出最佳的产氢速率(1.554 mmol·h^(-1)·g^(-1)),是Mn 0.3 Cd_(0.7)S的5.5倍。且经过四次循环实验后仍保持较好的光催化活性。此外,根据电化学测试以及红外热成像结果提出了合理的机理,Cu 3Mo 2O 9的光热效应与S型异质结的协同作用是Cu_(3)Mo_(2)O_(9)/Mn_(0.3)Cd_(0.7)S光催化活性提高的关键。

DNA barcoding of fishes from Zhoushan coastal waters using mitochondrial COI and 12S rRNA genes

Accurate species identification is a key component of biodiversity research.DNA barcoding is an effective molecular method used for fish species identification.We aimed to study the DNA barcoding of fish in Zhoushan coastal waters,explore the differences and applicability of two gene fragments(12S rRNA and COI)of DNA barcoding in fish species identification,and established a comprehensive fish barcoding reference database.Two hundred and eighty-seven captured fish samples from Zhoushan coastal waters were identified using morphological characteristics and DNA barcoding.A total of 26412S rRNA sequences(belonging to eight orders,31 families,55 genera,and 66 species)and 188 COI sequences(belonging to seven orders,30 families,48 genera,and 58 species)were obtained.The lengths of the 12S rRNA sequences ranged from 165 to 178 bp,and the guanine-cytosine(GC)content was 45.37%.The average 12S rRNA interspecific and intraspecific genetic distances(K2P)were 0.10%and 26.66%,respectively.The length of the COI sequence ranged 574–655 bp,and the content of GC was 45.97%.The average 12S rRNA interspecific and intraspecific genetic distances(K2P)were 0.16%and 27.45%,respectively.The minimum interspecific genetic distances of 12S rRNA and COI(1.23%and 1.86%)were both greater than their maximum intraspecific genetic distances(2.42%and 8.66%).Three molecular analyses(NJ tree,ABGD,and GMYC)were performed to accurately identify and delineate species.Clustering errors occurred when the 12S rRNA sequences were delimited using the NJ tree method,and the delimitation results of ABGD and GMYC are consistent with the final species identification results.Our results demonstrate that DNA barcoding based on 12S rRNA and COI can be used as an effective tool for fish species identification,and 12S rRNA has good application prospects in the environmental DNA(eDNA)metabarcoding of marine fish.

The diffusion and concentration effects of formamide on a TiO₂surface in the presence of a water solvent

The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological molecules needed for life. Titanium oxide (TiO2) can act as a strongly adsorbing surface or a catalytic material. In the present study, a comparative molecular dynamics analysis performed to clarify the adsorbing and diffusion properties of liquid formamide on a TiO2 surface in the presence of water molecules. The structural features of the formamide concentration effect (the accumulation of molecules) on a TiO2 surface in the presence and absence of water solvent are cleared up. Modification of the formamide diffusion abilities mediated by a water solvent is observed to correlate with the formamide-water concentration distribution on the surface.

基于射流补水的水泵水轮机S特性改善研究

针对水泵水轮机的“S”特性提出了在导叶顶盖位置无叶区处加装注水管的解决方案,并模拟了注水管安装在不同位置时的“S”特性曲线,分析了加装注水管后转轮区域内流线及转轮各叶道流量的分布规律。结果表明,于导叶顶盖加装注水管可以有效改善转轮内部流动,减轻转轮和导叶内部流动的相互影响,减小叶道涡的尺寸,同时有效缓解了转轮各叶道流量分布不均的现象。在注水管处于无叶区中段和活动导叶附近时,对“S”特性的改善效果明显。

H_(2)S在线监测装置研发及在锅炉水冷壁高温腐蚀防治中的应用

锅炉水冷壁高温腐蚀问题一直是影响锅炉安全运行的难题。为解决锅炉水冷壁高温腐蚀的主要媒介H_(2)S需要连续测量,但当前行业内缺乏能长期运行的H_(2)S在线监测装置问题,研发了基于可调谐二极管吸收光谱TDLAS原理测量锅炉水冷壁H_(2)S的监测装置,并使用装置在某300 MW等级电站锅炉上进行了示范应用,跟踪评估了该装置的性能。结果显示,基于TDLAS原理所研发的仪器在现场投运12个月以来保持稳定运行,装置在线监测结果显示炉内H_(2)S呈现脉冲式波动特点,H_(2)S浓度高时超过1600μL/L。监测中发现,炉内H_(2)S浓度与运行调整存在较密切的关系,在升负荷过程中,由2台磨转为3台磨运行时,前后墙23.60 m平台测点处H_(2)S浓度急剧增加,从46μL/L增至822μL/L,H_(2)S与脱硫塔入口SO_(2)没有显著的关联性。H_(2)S在线监测装置的成功研发可以实现锅炉主燃烧器区域关键参数的在线监测,并作为运行人员调整锅炉运行参数的主要依据,这对于锅炉高温腐蚀监测和锅炉数字化建设具有积极意义。

ALMOST ANALYTIC SOLUTIONS AND THEIR TESTS OF THE HORIZONTAL DIFFUSION EQUATION FOR THE MOVEMENT OF WATER IN UNSATURATED SOIL

This paper discusses the analytic solutions of the diffusion equation for the movement of water in unsaturated soil. Firstly, according to the experience relation between the diffusivity 'D(theta)' and water content in soil 'theta', and through variable substitution, the original diffusion equation is converted into the form easy to solve. Then, the variables separation method together with the Boltzmann transform method is used to find out the solution of the new partial differential equation. so the analytic function of 0(x, t) is obtained, which is verified by the experiment of water flow through unsaturated soil.

Density Functional Theory Study of Water Diffusion and Clustering on Pd(111)

The internal structures as well as adsorption and hopping energies of monomers, dimers, trimers, tetramers, pentamers and hexamers of water on Pd（111） have been studied by density functional theory （DFT） plane-wave pseudopotential method which performs the firstprinciples quantum-mechanical calculations to explore the properties of crystals and surfaces in materials. Based on the calculations, we suppose that their absorption is via one water molecule for monomers, dimmers and trimers, but three water molecules for pentamers and hexamers. Moreover, there is one water molecule bonding with Pd atom by O atom in pentamers and hexamers, which explains why pentamers and hexamers are stable. The binding energies of polymers may be used to explain why the trimer comes close to two nearby monomers to form a stable pentamer instead of tetramer. And the difference of mobility of small water clusters is due to their different hopping energies.

Diffusion analysis and modeling of kinetic behavior for treatment of brine water using electrodialysis process

In this study,the removal of monovalent and divalent cations,Nat,Kt,Mg2t,and Ca2t,in a diluted solution from Chott-El Jerid Lake,Tunisia,was investigated with the electrodialysis technique.The process was tested using two cation-exchange membranes:sulfonated polyether sulfone cross-linked with 10%hexamethylenediamine(HEXCl)and sulfonated polyether sulfone grafted with octylamine(S-PESOS).The commercially available membrane Nafion®was used for comparison.The results showed that Nafion®and S-PESOS membranes had similar removal behaviors,and the investigated cations were ranked in the following descending order in terms of their demineralization rates:Nat>Ca2t>Mg2t>Kt.Divalent cations were more effectively removed by HEXCl than by monovalent cations.The plots based on the WebereMorris model showed a strong linearity.This reveals that intra-particle diffusion was not the removal rate-determining step,and the removal process was controlled by two or more concurrent mechanisms.The Boyd plots did not pass through their origin,and the sole controlling step was determined by film-diffusion resistance,especially after a long period of electrodialysis.Additionally,a semi-empirical model was established to simulate the temporal variation of the treatment process,and the physical significance and values of model parameters were compared for the three membranes.The findings of this study indicate that HEXCl and S-PESOS membranes can be efficiently utilized for water softening,especially when effluents are highly loaded with calcium and magnesium ions.