A Comparative Study on the Nonspecific Immunity of Juvenile Litopenaeus vannamei ever Inhabiting Freshwater and Seawater

A study on the nonspecific immunity of Litopenaeus vannamei ever inhabiting freshwater and seawater was carried out at different molt stages by comparing their total hemocyte count(THC) and respiratory burst(RB) and activity of phenol oxidase(PO), nitric oxide synthase(NOS) and lysozyme(LY). Two-way ANOVA showed that salinity and molt stage independently affected THC and RB and the activity of PO, NOS and LY of juvenile L. vannamei significantly(P < 0.05). The THC and RB and the activity of NOS gradually increased from the post-molt stages(A and B) to the pre-molt stages(D0–D3), which were common in shrimps inhabiting freshwater and seawater. The activity of PO peaked at the inter-molt stage(C), and touched the lowest at the post-molt stage in freshwater and pre-molt stage in seawater. The activity of LY was stable over the molt cycle. The RB and the activity of PO, NOS and LY of juvenile L. vannamei were significantly lower in freshwater than in seawater; whereas THC was significantly higher in freshwater than in seawater(P < 0.05). It was concluded that the post-molt stage(especially stage A) was critical to shrimp culture, which should be intensively attended when L. vannamei was cultured in freshwater.

Ni Single Atoms and Ni Phosphate Clusters Synergistically Triggered Surface-Functionalized MoS_(2)Nanosheets for High-performance Freshwater and Seawater Electrolysis

Two-dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction(HER);however,their application is limited by a poor oxygen evolution reaction(OER)activity due to insufficient number/types of multi-integrated active sites.In this study,we report a novel bifunctional catalyst developed by simultaneous engineering of single nickel atoms(Ni_(SA)) and nickel phosphate clusters(Ni_(Pi)) to synergistically trigger surface-functionalized MoS_(2) nanosheets(NSs)resulting in high reactivities for both HER and OER.The Ni_(SA)-Ni_(Pi)/MoS_(2)NSs material exhibits a fairly Pt-like HER behavior with an overpotential of 94.0 mV and a small OER overpotential of 314.0 mV to reach 10 mA cm^(-2) in freshwater containing 1.0 M KOH.Experimental results of the catalyst are well supported by theoretical study,which reveals the significant modulation of electronic structure and enrichment of electroactive site number/types with their reasonably adjusted free adsorption energy.For evaluating practicability,the Ni_(SA)-Ni_(Pi)/MoS_(2)NSs-based electrolyzer delivers effective operation voltage of 1.62,1.52,and 1.66 V at 10 mA cm^(-2) and superior long-term stability as compared to Pt/C//RuO_(2) system in freshwater,mimic seawater,and natural seawater,respectively.The present study indicates that the catalyst is a promising candidate for the practical production of green hydrogen via water electrolysis.

Enhancement of freshwater production of the seawater greenhouse condenser

Seawater greenhouse(SWGH)is a technology established to overcome issues related to open field cultivation in arid areas,such as the high ambient temperature and the shortage of freshwater.It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body.Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand.The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs,simple design and high efficiency,and to explore the impact of the manipulating six operational variables(inlet air temperature of the humidifier,air mass flowrate of the humidifier,inlet water temperature of the humidifier,water mass flowrate of the humidifier,inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier)on freshwater condensation rate.For this purpose,a direct contact condenser was designed and manufactured.Sixty-four full factorial experiments were conducted to study the effect of the six operational variables.Each variable was operated at two levels(high and low flowrate),and each experiment lasted for 10 min and followed by a 30-min waiting time.Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min.When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production,it was found that the inlet air temperature of the humidifier had the greatest influence,followed by the inlet water temperature of the humidifier;the former had a negative impact while the latter had a positive impact on freshwater production.The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode.The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.

THEORETICAL AND EXPERIMENTAL RESULTS ON THE KINETICS OF CALCITE DISSOLUTION AND PRECIPITATION

INTRODUCTION Dissolution and precipitation of carbonates plays an important role in nature, such as in the chemistry of seawater, the sedimentation of carbonate at the seafloor, the geochemical evolution of freshwater aquifers and last but not least, most spectacular, the evolution of karst landscapes. To provide a deeper understanding to all these processes knowledge is required

China's Seawater Desalination Plants Produce Megatons Freshwater For Low Cost

China, as many other parts of the world, has a serious shortage of water resources. In China, there is a total amount of 2.8×10^12 m3 of freshwater, but that is only 2000 m3 per capita, which is about one quarter of the world average. Thereforc, seawater desalination engineering is of great significance to the nation.

硫酸盐和氯盐对海水海砂混凝土早期抗压强度的影响

对比研究了淡水河砂混凝土(SC)和海水海砂混凝土(SSC)的抗硫酸盐侵蚀和抗氯离子侵蚀性能。配制了不同水胶比的混凝土,经不同硫酸盐溶液浸泡后,测定了其早期抗压强度和抗压耐蚀系数;经5%NaCl溶液浸泡后,测定了其抗氯离子侵蚀性能。结果表明:硫酸盐溶液或Na Cl溶液浸泡有利于提高SSC的3 d抗压强度,但对7 d抗压强度会产生不利影响;SC的抗硫酸盐和抗氯离子侵蚀能力随着龄期的增长要优于SSC。水胶比对SC和SSC的抗压强度影响明显,水胶比为0.45时混凝土的抗压强度要高于0.50水胶比下的抗压强度;高水胶比时SSC的抗硫酸盐侵蚀和抗氯离子侵蚀能力优于低水胶比的。

市售鱼类中双酚A、双酚S污染水平及风险评估

目的:建立固相萃取和超高效液相色谱-串联质谱法测定鱼类中双酚A(Bisphenol A,BPA)及双酚S(Bisphenol S,BPS)的方法。方法:使用固相萃取和超高效液相色谱-串联质谱方法分析240份鱼类样品中BPA和BPS含量,并计算膳食暴露量和风险指数。结果:240份鱼类中均未检出BPA。BPS检出率为81.67%,含量检测最大值为65.31μg·kg^(-1),中位数为5.28μg·kg^(-1),平均值为12.99μg·kg^(-1)。结论:鱼类食品中检出BPS,未检出BPA。日常食用海水鱼或是淡水鱼都不会引起暴露风险。

Cation-Dipole Interaction-Induced Coacervate Underwater Adhesives in Natural Seawater

Significant progress has been made in wet adhesives for low salinity water,but exploration of general ionic adhesives for natural seawater is less developed because the high salinity could weaken interfacial bonding and shields electrostatic interactions,resulting in adhesion failure.Thus,the design of adhesives for natural seawater represents challenges less resolved.Herein,a cationic polyelectrolyte(PECHIA)containing imidazolacetonitrile unit was explored to prepare adhesives enabled by natural seawater.By combining the ion shielding effect with the“cation-dipole”interactions between PECHIA chains,aqueous solution of the PECHIA underwent coacervation and self-crosslinking in natural seawater,allowing for underwater adhesion to various substrates in seawater.The instantaneous lap-shear and tensile adhesion strengths are 47 and 119 kPa,respectively,while the cured adhesive shows~739 k Pa tensile adhesion in natural seawater.The design of PECHIA enables wet adhesives viable for applications in the diversified scenarios of natural seawater.

新型热泵增湿除湿海水淡化系统性能研究

为解决增湿除湿海水淡化技术高能耗问题,提出了一种新型热泵增湿除湿海水淡化系统,将热泵蒸发器用作二级除湿器,并增设过冷器对深度除湿后的空气进行复温。选用R134a为热泵工质,通过数学模型的建立与求解,分析讨论了制冷剂充注量、进料海水温度和液气质量比对系统性能的影响,并与现有文献中的热泵增湿除湿海水淡化系统性能进行对比。结果表明,系统存在最佳的制冷剂充注量、进料海水温度和液气质量比;当进料海水流量为720 kg/h时,最佳制冷剂充注量为240 kg/h,对应的最佳淡水产量和造水比分别为28.83 kg/h和7.21,均优于文献报道值,表明新系统具备实际产品开发的价值和广阔的应用前景。

海水腐蚀对砂岩物理力学特性与微观结构破坏特征的影响研究

针对海底隧道围岩在海水腐蚀下物理力学性能劣化的问题,选取典型砂岩作为研究对象,基于深圳海底隧道所在区域海水的取样数据配制不同浓度的模拟海水溶液,对砂岩试样进行不同浓度、不同时间的腐蚀浸泡处理,再进行单轴压缩试验,并结合声发射与扫描电子显微镜(SEM)技术,对海水腐蚀损伤砂岩的物理力学特性、破坏过程和微观结构演化特征进行分析研究。结果表明:随着腐蚀溶液浓度增加,砂岩试样表面越早发生脱落且面积越大,试样密度小幅度增加;峰值应力和弹性模量均随腐蚀时间增加而降低,但二者降低幅度及速率不同;随着腐蚀时间以及浓度的增加,除高浓度组砂岩试样在腐蚀45 d之后声发射事件活跃期有所缩短外,其余组砂岩试样的声发射事件活跃期均有所增长,砂岩试样内部缺陷逐渐发育,结构逐渐疏松,蜂窝状腐蚀区域面积增大,盐离子白色结晶区域逐渐扩大。

海水泵出口管路振动特性分析

管路在船舶上广泛存在,一般通过管道附件相互连接,组成管路系统。但是由于船舶运行工况的改变,管路中的流体湍流压力波脉动和管路结构之间容易发生耦合,从而引起管路系统的振动与噪声,对船舶设备的性能和安全提出挑战。本文以海水泵出口L型弯管段为研究对象,基于流固耦合理论,采用ANSYS Workbench仿真软件,分析其在管内海水瞬时压力脉动激励下发生的振动特性。最后基于谐响应分析结果,对管路特定部位加装弹性支架以实现船舶管路系统的减振降噪效果。

Research on changes of hydrodynamics and ion-exchange adsorption in Brackish-Water Interface

In light of multiple field experiments in typical tidal areas with active sea-land interaction, corresponding analysis through hydrodynamic simulation and of ion composition evolution all insist on following conclusions. Due to the tide, the groundwater level is basically in line with its level but with a slight lag. Moreover, smaller amplitude of such changes were always accompanied by greater distance from shores. In this paper, two salt-freshwater interfaces were identified, namely, a large wedge-shaped interface and an inverted U-shaped one located at K5 (monitoring point). The critical hydraulic gradient of saltwater intrusion was between 0.0345 and 0.0377. Apart from that, mathematical and physical models were adopted to measure the influence of tides, showing a inverse proportion to the hydraulic gradient In addition, characteristics of ionic components can prove that K^+ was adsorbed and Ca^2+ was displaced during saline intrusion, while a reverse process was witnessed during desalting. In summary, cation exchange adsorption plus other complex physical chemical effects would take place during saltwater intrusion.

基岩海岛地下水与海水相互作用研究

中国北方基岩海岛水文地质条件独特,气候变化和人类活动不同程度地影响着海岛地下水与海水相互作用过程,然而对包括海水入侵(SWI)和海底地下水排泄(SGD)的水文过程的定量认识比较缺乏。本研究基于2012—2016年我国北方某基岩群岛降水、地下水水位、水质动态监测数据,运用数理统计、空间插值和水力学方法,分析了基岩海岛地下水与海水相互作用的特征和影响因素。结果表明,降水和开采是影响地下水、海水相互作用的主要因素,地下水水位变化滞后于降水事件约10 d;南岛东北岸、南岸的大部分地区没有发生海水入侵,地下水向海排泄过程较稳定,2012—2016年SGD速率均值为0.2 m/d,向海NO3-N通量均值为81.8 mmol/(m^(2)·d);北岛东南地区是海水入侵的严重区域,地下水水位长期低于海平面且逐年下降,2012—2016年SWI速率均值为0.3 m/d,向陆NO3-N通量均值为69.6 mmol/(m^(2)·d)。分别计算南、北两岛枯水季(2014年4月)、丰水季(2013年9月)SGD水量,北岛SGD水量为3.5×10^(4)~4.5×10^(4)m^(3)/d,南岛SGD水量为0.4×10^(4)~1.1×10^(4)m^(3)/d。相关结果可为基岩海岛地下水资源管理和生态环境保护提供重要参考。

X65钢在模拟海底管道封存环境中的腐蚀行为

通过极化曲线、宏观腐蚀形貌、微观腐蚀形貌、腐蚀速率和三维点蚀形貌等,分析了X65钢在海水和淡水以及添加不同种类脱氧剂和缓蚀剂环境中的腐蚀行为。结果表明:在海水中添加缓蚀剂后,X65钢的自腐蚀电位最大正移量为11.6 mV,进一步添加脱氧剂后,其自腐蚀电位最大正移量为51.5 mV;随着浸泡时间的延长,试样表面生长出更为致密的腐蚀产物膜,最大点蚀速率从0.8812 mm/a降至0.6804 mm/a,该产物膜对试样表面起到保护作用;在海水中添加脱氧剂和缓蚀剂后,X65钢的最大点蚀速率下降至0.1068 mm/a,进一步印证了脱氧剂和缓蚀剂的协同作用能更有效缓解溶解氧腐蚀,在X65钢海管封存过程中推荐添加脱氧剂+缓蚀剂HYH-80-SEA;常温下X65钢在海水中的腐蚀速率为淡水中的10倍,而在海水中添加脱氧剂和缓蚀剂HYH-80-SEA后,其腐蚀速率仍为淡水中的2~4倍。

平面P_(1)波入射下双层衬砌对海底隧道地震响应的影响

将海水和海床土分别视为理想流体和饱和多孔介质,基于理想流体波动理论和Biot流体饱和多孔介质理论,考虑海水-海床土-隧道结构动力相互作用,利用波函数展开法和Hankel函数积分变换法,给出平面P1波入射下海底双层衬砌隧道地震响应的解析解。与以往的“大圆弧假定”方法相比,Hankel函数积分变换法可以将海底双层衬砌隧道场地中的散射波场势函数从柱坐标系下直接转换到直角坐标系下,可以更好地处理海水层表面和水土交界面处边界条件。在解析解的基础上,分析内外衬砌刚度比和内外衬砌厚度比对海底双层衬砌隧道位移响应和应力响应的影响,对海底双层衬砌隧道的抗减震设计提出合理建议。研究结果表明:①海底双层衬砌隧道的应力响应明显小于同参数条件下的单层衬砌隧道;②内外衬砌刚度比和厚度比对隧道位移响应的影响与隧道衬砌位置有关;③随着内外衬砌刚度比和厚度比的增加,隧道外衬砌应力响应均有减小趋势;④综合内外衬砌刚度比和厚度比对隧道位移响应和应力响应影响,海底双层衬砌隧道抗减震设计时,隧道内外衬砌刚度比和厚度比的选取范围分别建议为E_(2)/E_(1)≤3和δ_(2)/δ_(1)≤2。

Optimization of the Superglue Fuming and Powder Technique for the Enhancement of Latent Fingerprints from Objects Submerged in Water: An Experimental Study in Ghana

Introduction: Criminals’ propensity to precautionary mask their tracks such as disposing of an item of evidence in an aquatic environment (including freshwater and seawater) warrants the ongoing quest for advanced reagents and techniques that are tailored to the substrate characteristics on which the print will be developed. Aim: The study aimed to evaluate the synergic efficiency of the superglue fuming technique (using a homemade fuming chamber) and the powder technique in the development and visualization of latent fingerprints (LFPs) from different nonporous substrates submerged in an aquatic environment for up to 120 days. Materials and Methods: All selected nonporous substrates were cleaned thoroughly with a 70% alcohol swab. Natural latent prints were obtained from a single donor and the substrates were exposed to an aquatic environment. The superglue fuming (using a homemade fuming chamber) plus the powder technique was employed to develop and visualize the print. Results: Our findings disclose that the use of the superglue fuming technique together with the powder technique enhances the recovery rate of LFPs from substrates kept underwater for up to 90 days. The development of fingerprints was challenging from the substrates that were submerged in water for exactly 120 days. Conclusions: The resulting efficiency of the combined technique (superglue fuming technique using a homemade fuming chamber + powder technique) is substantially more sensitive, and selective, and performs better than the previously used stand-alone fingerprint enhancement technique. The improvised homemade fuming chamber proves to be a viable alternative to the standardized fuming cabinet in terms of functionality and sensitivity.

防污涂料淡水和海水浸泡性能的对比研究

选取市场上常见的不同技术类型的防污涂料,研究不同浸泡周期下,防污涂料在淡水和海水中以及不同海水深度下的性能表现。结果表明,海水深度越浅,生长污损的风险越高,硅烷类水解型防污涂料的静态防污性能更好。防污涂料在淡水中更容易出现起泡和发黏的情况,丙烯酸硅烷和甲基丙烯酸硅烷防污涂料的吸水率更低,起泡和发黏情况更少。该研究结果为码头舾装阶段的防污涂料选择和造船工艺改进提供了参考。

某2×1000 MW燃煤电厂淡水获取方案探讨

[目的]2×1000 MW燃煤机组的淡水用量约为500多t/h,如何获取这部分淡水对于电厂的安全、经济地运行至关重要。[方法]文章通过对滨海电厂的几种淡水获取方案进行技术和经济方面的对比分析,希望对特定边界条件下的淡水方案决策提供一些建议。[结果]通过文章探讨发现,自来水取水方案供水成本较低,但存在取水协议、输水管线征地等问题。海水淡化虽然节省淡水资源,具有良好的社会效益,但投资较大,运行维护工作量大,运行费用较高,供水成本高。[结论]2种淡水获取方案均可行,在有充足的自来水可获取的情况下,建议采用自来水作为电厂的淡水水源。

盐度变化对崇明东部河口潮滩氮营养盐循环影响实验模拟研究

以长江口咸淡水交互作用最为典型岸段崇明东部潮滩作为研究区域,运用实验模拟方法,定量地研究了盐度变化对潮滩生态系中无机氮的迁移、转化过程的影响。结果发现,盐度升高有利于沉积物中的NH4-N向上覆水扩散,但NO2-N和NO3-N的界面扩散呈现相反的变化趋势;沉积物中可交换态无机氮含量变化特征显示,在盐度变化剧烈的潮滩生态系统内,硝化作用可能是控制沉积物(尤其是表层沉积物)中无机氮分布的重要因素。

等量海水与淡水淹溺对兔肺损伤作用的比较

目的:比较等量海水与淡水灌注对兔肺损伤程度的影响。方法:健康成年新西兰兔24只,随机分为3组(n=8):对照组、海水灌注组(经气管插管灌注配方海水2ml/kg,约5min灌注完)、淡水灌注组(同海水灌注组方法灌注淡水2ml/kg)。连续180min观察各组灌注前后呼吸频率、体循环参数、动脉血气和血清肿瘤坏死因子α(TNF-α)、IL-6的变化。实验终点处死动物,观察肺泡灌洗液细胞计数和分类、肺组织湿/干质量比、肺微血管通透指数、肺病理组织学等。结果:灌注后动物呼吸明显增快(P<0.01),体循环平均压下降(P<0.01),导致低氧血症及低碳酸血症,血清TNF-α、IL-6等炎症因子水平增高(P<0.01),肺组织病理损伤重,且海水组较淡水组变化显著且持久;海水组肺组织湿/干质量较其他两组增大、肺微血管通透指数较其他两组增高(P<0.05),支气管肺泡灌洗液中细胞数量较对照组增多(P<0.01),肺损伤程度明显重于淡水灌注组。结论:等剂量海水与淡水灌注比较,海水致兔的肺损伤程度重,病情发展快,病变更持久。