The Influence of Free Water Content on Dielectric Properties of Alkali Active Slag Cement Paste

The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste were mostly influenced by the fraction of free water in paste or absorbed water from ambient, but not including hydration water and microstructure. The free water was completely eliminated by heat treatment at 105 ℃ about 4 hours, and then its dielectric loss was depressed; but with the exposure time in air increasing, the free water adsorption in ambient air made the dielectric property of harden cement paste to be bad. The temperature and relative humidity of environment was the key factors of free water adsorption; hence, if the influence of free water on dielectric constant was measured or eliminated, the cement-based materials may be applied in humidity sensitive materials or dielectric materials domains.

Experiment and Numerical Simulation of Free Water Jet by a Central-body Nozzle

The recent research about cavitation jet mainly focuses on the organ-pipe nozzle and triangular nozzle. The research content mainly includes the optimized design about the structure of nozzles, the observation and flow analysis about the cavitation jet in the water, and the theory of rock attacked by the cavitation jet, while the energy characteristic of the free jet is not studied yet. In China, the research about the central-body nozzle is almost empty. For the purpose of studying the energy characteristic and the structure of free water jet discharged from central-body nozzle, an experiment with phase Doppler particle anemometry（PDPA） technology is carried out to measure the free water jet flow, which is produced by a central-body nozzle under the jet pressure of 15 MPa. While five sections with different axial distances from the nozzle outlet are selected for data process and analysis, the axial and radial velocity and the droplets of the particle size are studied. Meanwhile, numerical calculation of corresponding flow field is conducted by using volume of fluid（VOF） multiphase model, and the jet flow feature is discussed. The experimental and calculating results show that the axial velocity of high speed jet flow dissipates slowly in the air, and the core area and diffused area are discovered. The diameter of droplet in the core area is small, and jet energy is concentrated, while in the diffusion area, water is mingled with ambient air and radial velocity is relatively large. Obvious low-pressure area exists behind the central body and potential cavitation may occur in that area. The proposed research reveals the energy characteristic of free jet discharged from central-body nozzle, provides the theoretical basis for preestimating erosion feature of the central-body nozzle and also the theoretical foundation for revealing the mechanism of erosion.

Effects of a Free Water Protocol on Inpatients in a Neuro-Rehabilitation Setting

Background: Dysphagia is common among stroke and acquired brain injury (ABI) patients and may result in aspiration. To reduce the risk of thin liquid aspiration, patients are often restricted to thickened fluids. There is considerable clinical interest in the risks and benefits of offering oral water intake, in the form of water protocols, to patients with thin-liquid dysphagia. Objectives: A controlled pilot study of a free water protocol was undertaken at Riverview Health Centre, in Winnipeg, Manitoba to assess benefits, feasibility and possible complications of free water protocol. Methods: The study examined 16 individuals with stroke or ABI who were randomly assigned to either a control group on thickened fluids (six subjects) or a treatment group (ten subjects) that followed a free water protocol. The average length of time in the study was 4.3 weeks with a range of 1 - 17 weeks among all participants. Results: Throughout the study, there was no incidence of pneumonia in any of the sixteen participants. No statistically significant difference was noted in the weekly total liquid intake between the treatment group and the control group. Perceived swallowing related care results suggest statistically significant improvements from initial to final measures for both the treatment group (p = 0.004) and the control group (p = 0.02). However, a comparison of the change in both measures, between the treatment and control groups, shows no statistically significant differences. Conclusion: This pilot study suggests the need for larger scale work in order to more accurately identify the effects of free water protocols.

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed wetlands,were investigated with laboratoryscale systems.N_(2)O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent,and the total N_(2)O emission in the system with middle COD influent concentration was the least.The relationships between N_(2)O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N_(2)O flux.The multiple linear regression model against principal components indicated that different water parameters affected N_(2)O flux with different COD concentrations in the influent,but nitrate nitrogen affected N_(2)O flux in all systems.

Numerical Simulation of the Water Entry of a Structure in Free Fall Motion

为了有关结构， RANS 方程和液体(VOF ) 的体积的水入口解决这些问题，方法被使用。把自定义功能(UDF ) 过程与动态格子相结合，在免费秋天的结构上的水影响被模仿，并且结构上的速度，排水量和压力分发被调查。数字模拟的结果与试验性的数据相比，并且坚硬地一致的结果被完成了它验证数字模型。因此，这个方法能被用来学习结构的水影响问题。

Detection of Cyanide in Pollution-free Livestock Product Breeding Water by Ion Chromatography

In order to verify the accuracy of ion chromatography for cyanide detection,optimization conditions were studied,and comparison was made for the detection results of cyanide between titration and isonicotinic acid pyrazolone spectrophotometry. The results showed that ion chromatography has good linearity and reproducibility,with the recovery rate of 95%-105% and the limit of detection of 0. 001 mg/L. This method is simple,rapid,safe,selective,and suitable for the determination of cyanide in pollution-free livestock product breeding water.

Modulating the properties of monolayer C2N:A promising metal-free photocatalyst for water splitting

Photocatalytic water splitting has gained increasing attention, since it utilizes renewable resources, such as water and solar energy, to produce hydrogen. Using the first-principles density functional theory, we investigate the properties of the single layer C_2N which was successfully synthesized. We reveal that monolayer C_2N has a substantial direct band gap of 2.45 eV. To regulate its band gap, four different nonmetal elements（B, O, P, and S） on the cation and anion sites are considered. Among them, B-doped N site is the most effective one, with the lowest formation energy and a band gap of 2.01 eV. P-doped N site is the next, with a band gap of 2.08 eV, though its formation energy is higher. The band alignments with respect to the water redox levels show that, for these two dopings, the thermodynamic criterion for the overall water splitting is satisfied. We therefore predict that B-or P-doped C_2N, with an appropriate band gap and an optimal band-edge position, would be a promising photocatalyst for visible-light water splitting.

Antimicrobial Resistant Coliforms in Tap Water with Low Free Residual Chlorine Levels in Two Hospitals: Case Study in Gaza, Palestine

Universal access to safe water, whether at households or health centres, is central to achieving the sixth sustainable development goal by 2030. A hospital-based survey was conducted to screen for antimicrobial resistance among coliforms in samples collected from tap water (n = 54) at surgical wards in Gaza and to investigate the association with free residual chlorine and pH levels. Total coliforms (TC) were detected in 48.1% (26/54) of tested samples and FCs were detected in 25.9% (14/54). Free residual chlorine test ranged from zero to 0.2 mg/l (average: 0.08 mg/l), of which more than half of the samples (53.7%) 29/54 showed no free residual chlorine. The mean value of free residual chlorine in samples tested positive for growth on m-Endo (0.03) was lower than the mean for negative samples (0.14). The pH values were within the acceptable range (average: 7.6) and there was a statistically significant variation between the mean of pH values for samples tested positive on m-Endo (7.29) and that tested negative (7.84). Among coliform positive samples, 23.1% (6/26) had coliform isolates with resistance patterns. More than two-thirds of antimicrobial resistant (AMR) isolates were resistant to amikacin, ceftazidime, ceftriaxone, and imipenem. Moreover, 50% of the isolates were resistant to piperacillin-tazobactam. One-third (33.3%) of isolates were resistant to cefoxitin, and fosfomycin, 16.7% were resistant to ciprofloxacin, and nitrofurantoin. Intermediate resistance was shown in 16.7% of the isolates to cefoxitin and ciprofloxacin. The ESBL and carbapenem resistance genes detected in isolates were TEM (66.7%), NDM (33.3%), OXA (25%), blaCTXM (16.7%), and blaCTXM-3 (16.7%). The finding highlighted the level of contamination with AMR coliform in samples collected from tap water and pointed out the importance of managing water safety through identifying the main source of contamination, in addition to maintaining proper water disinfection at healthcare facilities for the patient, staff and environmental safety.

Free proline accumulation in rice plants under different leaf water potential

Seedlings of drought-tolerance rice varieties Han 501and Han A03,and the drought sensitive varietiesNanjing 11 and Yanjing 2 were raised in a paddyfield and transplanted into pots at the age of 8leaves.Water stress started at the tillering stage byholding water from 0 MPa of the soil water potentialin pots till the leaves showed seriously wilting.

A Study on the Structure and Behavior of Sinter-free Material for Phosphorous Removal from Waste Water

Oyster shell and cement were taken as the major raw materials to fabricate hollow, tubular and recoverable material for phosphorous removal （P removal） from waste water without sintering. In this paper, the effects of different affecting factors on the sample P removal ratio were discussed to select optimal P removal process conditions. SEM and XRD were used to characterize the microscopic structures and composition of samples, and molybdenum blue spectrophotometry was applied to determine the P content in waste water. Results showed that at 30 ℃ for 2 d, the P removal ratio reached 93.3% when the cement content was 10 wt% and oyster shell powder was 90 wt%. SEM analysis revealed a flaky structure consisting of phosphorus-containing compound in the samples after P removal, and it piled on and maintained the porous structure. In addition, the results also suggested that raising the ambient temperature was benefit to the P removal. The P removal ratio of the material was optimal under neutral and alkali conditions.

Development and applications of solids-free oil-in-water drilling fluids

The increasing application of near balanced drilling technology to low-pressure and depleted fractured reservoirs requires the use of low-density drilling fluids to avoid formation damage. Solidsfree oil-in-water （O/W） emulsion drilling fluid is one type of low-density drilling fluid suitable for depleted fractured reservoirs. In this paper, the solids-free O/W drilling fluid was developed and has been successfully used in the Bozhong 28-1 oil and gas field, by which lost circulation, a severe problem occurred previously when drilling into fractured reservoir beds, was controlled, thereby minimizing formation damage. The O/W emulsion drilling fluid was prepared by adding 20% （by volume） No. 5 mineral oil （with high flash point, as dispersed phase） into seawater （as continuous phase）. Surfactant HTO-1 （as a primary emulsifier） and non-ionic surfactant HTO-2 （as a secondary emulsifier） were added into the drilling fluid system to stabilize the emulsion; and YJD polymer was also added to seawater to improve the viscosity of the continuous phase （seawater）. The drilling fluid was characterized by high flash point, good thermal stability and high stability to crude oil contamination.

Oblique Wave-free Potentials for Water Waves in Constant Finite Depth

在这份报纸，与一致有限深度为水在水波浪的 linearised 理论构造倾斜的没有波浪的潜力的一个方法以一种系统的方式被介绍。水把免费表面或一个冰封面作为一个薄有弹性的盘子建模。为免费表面的盒子，表面紧张的效果可以被忽视或考虑。这里，没有波浪的潜力是修改 Helmholtz 方程的单个答案，有在在液体区域的一个点的奇特，他们很快在上面的表面和水区域和腐烂的底部满足条件离开奇特的点。这些在获得解决方案到与象长水平的柱体那样的圆形的剖面图包含身体的倾斜的水波浪问题是有用的沉没或在有作为一块漂浮的橡皮建模的免费表面或一个冰封面的一致有限深度的水里沉浸一半板。最后，与这里构造的没有波浪的潜力有关的上面的表面的形式在很多个数字图形地被描绘设想波浪运动。非倾斜的没有波浪的潜力和上面的表面的结果没有波浪的潜力被获得。这里构造的没有波浪的潜力将在水里在包含无穷地长水平的柱体的水波浪问题的数学学习是有用的、也沉浸一半或完全沉浸。

深部煤层气水赋存机制、环境及动态演化

准确认识深部条件下气体和水分的赋存状态、相对含量及分布特征,对煤层气高效勘探开发具有重要指导意义。基于理论模型、分子模拟和气水演变分析,明确了煤层中气、水的赋存状态,揭示了气、水动态运聚界限和动态演化过程。考虑煤-水界面作用、水的可动性及赋存状态,煤中水可分为可动水(重力水和毛细水)、束缚水(吸附水、沸石水、结晶水和层间水)、结构水,其中毛细水、重力水和吸附水由孔隙主导,沸石水、结构水、结晶水和层间水由矿物主导。分子模拟结果显示,水分子在0.7 nm孔隙中可以饱和充填,吸附和解吸路径一致,在更大孔隙中出现弱吸附层和自由态。水分子吸附过程表现为单分子含氧基团吸附、单层强吸附、多层弱吸附、水团簇形成和充填孔隙等阶段。甲烷分子在1.5 nm孔隙可存在3层稳定充填吸附,在较大孔隙中(>1.5 nm)即以单层吸附和游离态共存,游离态在介孔及更大孔隙中普遍存在。结合上述吸附-游离气存在界限,改进了游离气和吸附气理论计算公式,为含气量计算提供新思路。深部热成因煤层气是煤大规模生排烃之后的残余气,在排烃过程中发生气驱水和水分蒸发扩散,残余水分为束缚水和结构水,后期无法改变。假定静水压力20 MPa,在0、5、10、15和20 MPa储层压力下,外来水分可入侵最大孔径为7、9、13、27 nm和不侵入。受差异保存条件控制,煤成气除了形成超压和欠压等差异含气系统外,还可能在煤系形成多类型含气模式。上述研究明确了煤层气、水微观赋存机制及形成演化模式,对深部煤层气富集特征及高效开发设计具有指导意义。

低温与无水胁迫下凡纳滨对虾肌肉品质劣变标记蛋白识别

【目的】探明凡纳滨对虾(Litopenaeus vannamei)保活流通过程中低温和无水双重胁迫诱导肌肉品质劣变与差异表达蛋白之间的相关性,识别品质劣变的潜在标记蛋白。【方法】在模拟的海水环境中[溶解氧质量浓度为7.2 mg/L,温度控制在(12±1)℃]观察对虾在低温和无水胁迫下的生理反应,通过串联质谱标签蛋白质组学方法,分析环境胁迫导致的肝胰腺蛋白质组显著差异性变化,并将其与肌肉品质进行相关性分析。【结果】与正常对照组相比,低温组和低温+无水组分别鉴定了33和44个显著差异蛋白质(DEPs),这些蛋白质大多在溶酶体、糖酵解或糖异生、黏附等通路显著富集(P<0.05),同时胰蛋白酶-1、二肽基肽酶显著上调(P<0.05),而磷酸丙糖异构酶和醛脱氢酶显著下调(P<0.05)。此外,颜色和质构指标的变化与微管蛋白、凝溶胶蛋白、层黏连蛋白、内源性蛋白酶和代谢酶表达水平显著相关。【结论】本研究初次探明肝胰腺DEPs与肌肉品质间的内在联系,识别的典型DEPs可作为品质劣变的潜在标志蛋白,为监测无水运输期间凡纳滨对虾肌肉品质劣变提供分子靶标。

北方不冻水域落单中华秋沙鸭及其混合群的越冬对策

中华秋沙鸭,是我国的濒危物种之一,通常在中国长江流域尤其是江西省越冬,但也存在少数个体在北方不冻水域越冬,研究中华秋沙鸭的越冬行为对于全面了解其种群数量与分布、生境选择,进而对其进行保护具有重要意义。2020年12月-2021年2月和2022年1-2月,在辽宁省本溪市太子河不冻水域,采用瞬时扫描法和固定样点法观测越冬的中华秋沙鸭及与该鸟混群的普通秋沙鸭的越冬行为,并对两者进行比对,同时还收集了在江西等地越冬的中华秋沙鸭群体行为数据,与本溪越冬的中华秋沙鸭进行比较。结果发现,连续2年均只有1只雄性中华秋沙鸭在该地越冬,而这些落单的中华秋沙鸭均选择与其亲缘关系较近的普通秋沙鸭混群,并且在栖息地选择方面表现出较强的特异性,同时在觅食、游泳、休息、游戏和梳羽等方面与普通秋沙鸭不存在差异。相反,本溪中华秋沙鸭的行为节律与江西等地越冬的中华秋沙鸭群体存在明显差异,暗示落单的中华秋水鸭的越冬行为可能受到温度及其混群对象的影响。

花生粕发酵工艺条件优化及其提取物体外抗氧化活性研究

试验以花生粕为原料,利用乳酸菌、芽孢杆菌和酵母复合发酵技术进行固态发酵,探究不同含水量、接种量、发酵时间对发酵花生粕体外抗氧化活性的影响。利用3因素3水平的响应面试验设计对花生粕发酵条件进行优化,以发酵花生粕水溶性提取物对1,1-二苯基-2-三硝基苯肼(DPPH)清除率为评价指标,确定最适发酵条件。同时考察提取物对2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐自由基(ABTS^(+)·)、羟自由基(·OH)、DPPH自由基清除率和铁还原能力的影响,来评估其体外抗氧化活性。响应面优化结果为含水量52%、接种量5%、发酵时间85 h,在此条件下发酵的花生粕,其水溶性提取物对DPPH的清除率可达到60.58%,比未发酵花生粕的52.96%提高了14.39%(P<0.05)。体外抗氧化活性研究结果显示:当提取物质量浓度大于0.2 mg/mL时,发酵组对ABTS^(+)·、·OH清除能力以及铁还原能力显著高于对照组(P<0.05),当提取物质量浓度大于0.8 mg/mL时,发酵组对DPPH自由基清除能力显著高于对照组(P<0.05),但均显著低于L-抗坏血酸(VC)组(P<0.05)。研究表明,发酵显著提高了花生粕的抗氧化活性,可为花生粕功能性物质的研发和高值化利用提供参考。

循环水槽船模阻力修正方法

在循环水槽中开展船模阻力测量是船型优劣分析的常规试验之一,因此对循环水槽阻力修正方法进行研究是十分必要的。以集装箱船标模(KCS)为研究对象在循环水槽中开展模型阻力和流场测量试验,根据循环水槽自身流动特性并结合拖曳水池已有的修正方法,分析并总结适用于水槽船模阻力与阻塞效应的修正方法。由总结的修正公式与修正流程可知,循环水槽中2.5~3.5 m尺寸模型试验与大模型试验结果阻力换算偏差在1%左右,设计航速点阻力换算偏差小于1%。结果表明,有必要对循环水槽中阻力进行自由面倾斜度修正,采用Tamura公式进行阻塞效应修正能得到更为精确的阻力试验结果。

耐久型水性杂化无氟防水剂的制备及其性能

针对当前无氟防水剂整理织物耐久性不佳的问题,引入低表面能聚硅氧烷链段和长碳链十六烷基,并通过对硅溶胶乳液进行氨基改性以提高有机硅改性聚氨酯有机组分和十六烷基改性硅溶胶无机组分的界面作用,制备了一种耐久型水性杂化无氟防水剂,并将其应用于涤纶/棉织物的防水整理。研究了防水剂的硅溶胶组分中氨基硅烷偶联剂质量分数、焙烘温度等因素对织物防水性能及防水耐久性能的影响,考察了防水整理织物的表面形貌及对不同液体的防水效果。结果表明:当γ-氨丙基三乙氧基硅烷(KH-550)质量分数为1.5%,焙烘温度为160℃时,防水剂可在涤纶/棉织物表面形成微纳米尺寸的粗糙结构的拒水膜,水接触角可达131.8°;经20次标准洗涤后,织物的水接触角仍可维持在129°,表现出良好的耐水洗性能。

巢湖十八联圩湿地浮游动物群落动态及水质评价

为了解巢湖重要入湖湿地十八联圩湿地生态修复后的水质和生物多样性恢复现状,于2023年冬季枯水期和夏季丰水期,在修复后湿地中选取11个样点开展浮游动物调查。结果表明:枯水期和丰水期分别检测出浮游动物82种和128种,平均密度分别为(6769.17±3814.42)个/L、(5417.35±5401.94)个/L,平均生物量分别为(1.28±0.65)mg/L、(3.44±2.57)mg/L。枯水期和丰水期Shannon-Wiener多样性指数均值分别为2.47和2.55,Margalef丰富度指数均值分别为3.04和4.20,Pielou均匀度指数均值分别为0.52和0.72。十八联圩湿地修复后水质有了较大的提升,水质呈无污或寡污状态。湿地单元能有效地提升浮游动物多样性和稳定性,在丰水期具有良好地水质净化效果。枯水期浮游动物群落结构主要受电导率(EC)、水温、溶解氧(DO)等因素的影响,丰水期营养污染物对群落结构的影响更大。冗余分析结果表明,氮元素是浮游动物生物量的关键影响因子,未来应当重点关注。

透镜飞行器击水弹跳运动数值模拟

探索跨介质飞行器水面弹跳过程中的运动特性和自由液面特性,对于跨介质飞行器的着水和弹跳复飞研究有着重要的参考价值。基于无网格粒子数值模拟方法研究透镜跨介质飞行器击水弹跳运动特性及液面变化特性,在与试验值对比的基础上,重点研究不同自旋速度、击水速度和击水角度对透镜飞行器击水弹跳运动特性及自由液面特性的影响。研究结果表明:自旋速度是保证透镜跨介质飞行器顺利实现击水弹跳运动的必要条件,受飞行器自旋速度诱导出现的触水区马格努斯效应会导致飞行器出现侧向运动;击水弹跳过程普遍包括稳定下落、击水、弹跳至平稳飞行三个阶段,自由液面受飞行器强烈冲击出现液面破碎和液体迸溅现象;击水弹跳过程中,飞行器击水速度衰减率及砰击载荷受自旋速度影响较小,主要受击水速度与击水角度影响,击水速度与击水角度越大,速度衰减率及砰击载荷越大。