Optimization of recharge and pumping rates by means of an inverse 3D model

The paper concerns the optimization of pumping and artificial recharge rates under hydraulic head constraints. This optimization is accomplished by means of an inverse three-dimensional (3D) model which is a combination of a numerical model, sensitivity analyses and nonlinear regression. The optimization criterion used is the minimization of the sum of the squares between the calculated and the desired water table maps. These maps were established for the end of each month of the period from December to August so that the annual average flux is outward from the modeling area. This outward flux will push back the salt water intrusion. The assumed natural recharge rates of the different months equal the mean values of the period 1958–1977. The aquifer parameters describing the water conducting and storing properties are also required as input data as well as the initial hydraulic heads. The optimized parameters are the artificial recharge rates of the months December, January, February and March and the pumping rates of the months April, May, June, July and August. For the first-mentioned months, the pumping rates are considered as known. During the last-mentioned period, no artificial recharge is possible. A unique solution is obtained. To check the optimized rates, a water balance is made. With this balance, it is shown that the treated phreatic aquifer can be used as a subterranean reservoir to store water that is abundantly present in the winter until the summer when water demand is large. It is also proved that the salt-water intrusion can be stopped by the temporal storage of the artificial recharged water.     

Salt‐Assisted Synthesis of 2D Materials

2D materials have demonstrated good chemical, optical, electrical, and magnetic characteristics, and offer great potential in numerous applications. Corresponding synthesis technologies of 2D materials that are high‐quality, high‐yield, low‐cost, and time‐saving are highly desired. Salt‐assisted methods are emerging technologies that can meet these requirements for the fabrication of 2D materials. Herein, the recent process for the salt‐assisted synthesis of 2D materials and their typical applications are summarized. First, the properties of salt crystals and molten salts are briefly introduced, and then some examples of 2D materials synthesis with the assistance of salt as well as their representative applications are presented. The underlying mechanisms of salts with different states on the formation of 2D morphology are discussed to aid in the rational design of synthetic route of 2D materials. At last, the challenges and future perspectives for salt‐assisted methods are briefly described. This review provides guidance for the controllable synthesis of 2D materials based on the salt‐assisted approaches.     

空位对五唑阴离子盐Mn（N5）2冲击反应和损伤演化的影响

为探究微缺陷对五唑阴离子盐冲击响应、化学分解及损伤演化的影响,采用从头算分子动力学模拟方法研究了完美型Mn（N₅）₂晶体及含有3%空位浓度的Mn（N₅）₂晶体在不同速度（8,9,10,11,12 km·s^-1）c轴冲击波作用下的动力学演化和初始分解反应机理。冲击雨贡纽线的计算结果表明,含空位的Mn（N₅）₂体系比完美型体系在高压条件下表现出更大的体积压缩比。分子动力学模拟结果显示,当冲击波速v_shock<10 km·s^-1时,完美型及含有空位的体系在5000 fs内均未出现分解反应,而仅出现了不足10%的体积压缩;当v_shock=10 km·s^-1时,完美型体系于512.8 fs时刻开始在晶体内均匀地出现N—N键断裂的现象,而含空位体系的初始反应时间则提前至281.6 fs,并且N—N键的断裂集中发生在空位附近;当v_shock继续增加至11 km·s^-1和12 km·s^-1时,两种体系的初始反应时间不断提前,反应进程不断加快,但空位对体系冲击波感度的提升作用和对分解反应进程的加速作用随着冲击波速的提升而不断减弱。研究结果表明空位是热点的早期成核结构之一,空位的存在促进周围的五唑分子发生级联分解,使损伤不断演化成长和传播,进而引起含能材料的点火。     

Supramolecular Chemistry in Molten Sulfur: Preorganization Effects Leading to Marked Enhancement of Carbon Nitride Photoelectrochemistry

Here, a new method for enhancing the photoelectrochemical properties of carbon nitride thin films by in situ supramolecular‐driven preorganization of phenyl‐contained monomers in molten sulfur is reported. A detailed analysis of the chemical and photophysical properties suggests that the molten sulfur can texture the growth and induce more effective integration of phenyl groups into the carbon nitride electrodes, resulting in extended light absorption alongside with improved conductivity and better charge transfer. Furthermore, photophysical measurements indicate the formation of sub‐bands in the optical bandgap which is beneficial for exciton splitting. Moreover, the new bands can mediate hole transfer to the electrolyte, thus improving the photooxidation activity. The utilization of high temperature solvent as the polymerization medium opens new opportunities for the significant improvement of carbon nitride films toward an efficient photoactive material for various applications.     

室温熔盐在碳纳米管电化学电容器中的应用

将碳纳米管制成薄膜电极,以二(三氟甲基磺酸酰)亚胺锂(LiTFSI)-1,3-氮氧杂环戊-2-酮(OZO)室温熔盐为电解液,装配成模拟电容器。测试结果表明,比电容为20.5F/g,工作电压可达2.0V以上,循环充放电500次后容量损失小于5%。室温熔盐在碳纳米管电化学电容器中表现出良好的电化学兼容性,具有良好的热稳定性,是超级电容器非常有前景的新型电解液。     

泥页岩水敏性对盐岩层塑性变形的影响

由于处在盐岩层夹层中的泥页岩水敏性的影响,经24小时吸附水化和渗透水化后的泥页岩膨胀压力高达36.44MPa。抑制泥页岩水敏性是控制盐岩层塑性变形的有效途径。     

4-氨基-1,2,4-三唑-NTO盐的晶体结构及性能

用X射线单晶衍射法测定了4-氨基-1,2,4-三唑(4-AT)与3-硝基-1,2,4-三唑-5-酮(NTO)制得的盐(AT)(NTO)的单晶结构。结果表明:该晶体为单斜晶系,属P21/c空间群,晶体学参数a=7.071(2),b=6.361(3),c=18.792(7);β=96.43(3)°;V=839.9(5)3;Z=4;Dc=1.694 g.cm-3;μ=0.145/mm;F(000)=440。在(AT)(NTO)晶体中,4-AT阳离子上所有的原子和NTO阴离子上所有的原子均在以各自三唑环为基础的一个平面上,两平面夹角为7.6°。由真空安定性(VST)、撞击感度、摩擦感度和静电火花感度试验所得的真空放气量、特性落高、爆炸概率、50%发火电压、50%发火能分别为0.28 mL.g-1(100℃/48 h),124.7 cm,0%,12.841 kV和2.515 J,表明,(AT)(NTO)对热是稳定的,对撞击、摩擦和静电火花是不敏感的。     

超临界二氧化碳富集提纯鱼油中EPA和DHA的研究进展（Ⅱ）鱼油的预处理和实验装置

综述了近年来人们用超临界二氧化碳（ＳＣ－ＣＯ_２）从鱼油中富集提纯ＥＰＡ（廿碳五烯酸）和ＤＨＡ（廿二碳六烯酸）的各类实验装置。讨论了鱼油的预处理方法、萃取操作条件对ＳＣ－ＣＯ_２提纯ＥＰＡ和ＤＨＡ的纯度和收率的影响。介绍了一个工业化双塔连续逆流萃取模拟流程。对我国鱼油资源的利用进行了分析。     

基于散热条件变化的弧焊熔透成形过程的数值模拟

利用有限元热场数值模拟技术,对焊接过程中变截面与非变截面焊件的温度场进行模拟计算,定量地得到了由于焊件变截面散热条件变化,导致熔池动态热输出及熔透变化的过程,通过两种焊件计算结果的对比分析,得出可通过焊件热影响区长度方面的温度梯度和宽度方向的温度梯度的变化来反映熔池热输出变化及热输出变化与熔透变化具有一定对应关系的结论,为进一在于能量平衡的熔透控制建立一定的理论基础。     

三聚氰酸为基的2,4,6-三氧-[1,3,5]三嗪烷-1-三氨基胍盐的合成、晶体结构和热性能（英）

以三聚氰酸钠(CANa)和三氨基胍盐酸盐(TAG-HCl)为原料,通过一步复分解反应制备了一种富氮含能化合物——2,4,6-三氧-[1,3,5]三嗪烷-1-三氨基胍盐(1),收率91%.采用X-射线单晶衍射、UV-Vis、FTIR、1H NMR以及元素分析等对产物进行了结构表征.计算了产物的生成焓和爆轰参数.通过差示扫描量热法(DSC,10 K·min-1)和热重-傅里叶变换红外光谱联用分析了其热稳定性、非等温热分解动力学和热分解过程.通过落锤法测试了产物的撞击感度.结果表明,化合物1的晶体为单斜晶系,P21/n空间群,计算密度为1.676 g·cm-3,生成焓为327.9 kJ·mol-1,爆速为7900 m·s-1,爆压为26.5 GPa.化合物具1有良好的热稳定性,分解峰值温度为538.9 K,提出了N2气氛下可能的热分解机理.且化合物1对撞击非常钝感,撞击感度大于60 J,优于TATB(50 J).