电热法测定冰的熔化热实验仪的研制

为了解决混合法测量冰的熔化热实验中热量损失的问题,设计了电热法测定冰的熔化热实验仪.真空保温杯和冰水混合物双重隔离实验对象,降低了冰与环境的热交换,通过移液管测量冰熔化成水的体积变化,进而测定冰的熔化热.     

海参胶原蛋白的提取及其基本成分的分析

提取海参中胶原蛋白并分析其基本成分.分别用碱解、酶解法提取胶原蛋白,Folin-酚试剂法测定多糖含量、蛋白含量,运用GC分析单糖成分.海参中多糖含量为14.35％,蛋白含量为0.989％.多糖的成分包括岩藻糖、甘露糖、半乳糖、葡萄糖,其中岩藻糖为主要单糖成分.本法简单,操作方便,实验灵敏,多糖得率高.     

降低真空制冰系统真空度的理论研究

文中针对真空冰浆制备系统运行真空度较高的问题进行分析,提出利用在水中加入中介物质的方法来降低制备系统对真空度的要求,并利用物质的化学势平衡理论与溶液相图相结合的方法,从理论上验证了在真空冰浆制备系统中加入中介物质具有降低系统对真空度要求的作用.     

微波消解-电感耦合等离子体-质谱和原子荧光光谱测定海产品中总砷含量差异的研究

对电感耦合等离子体-质谱和原子荧光光谱测定海产品中总砷的方法及结果进行了比较.HNO3-H2O2混合体系微波消解处理样品,总砷采用在线加内标、碰撞池模式、ICP-MS测定和加入预还原剂-氢化物发生原子荧光光谱测定,两种方法校准曲线的相关系数均大于0.9995,检出限分别为0.0023μg/L和0.029μg/L,加标回...     

Electrophilic Addition Reaction of Ethene with Hydrogen Chloride on Cold Molecular Films: Evidence of Ethyl Cationic Intermediate

We studied the initial‐stage mechanism of the electrophilic addition reaction of ethene with HCl by examining the interactions between ethene and HCl on water‐ice and frozen molecular films at temperatures of 80–140 K. Cs⁺ reactive ion scattering (RIS) and low‐energy sputtering (LES) techniques were used to probe the reaction intermediates that were kinetically trapped on the surface, in conjunction with temperature‐programmed desorption (TPD) mass spectrometry to monitor the desorbing species. The reaction initially produced the π complex of HCl and ethene at temperatures below about 93 K and an “ethyl cationic species” at temperatures below about 100 K. The ethyl cationic species was formed via direct proton transfer from the HCl molecule to ethene with the assistance of water solvation, rather than via the interaction of hydronium ions and ethene. At high temperatures, this species dissociated into ethene and hydronium and chloride ions. The reaction did not, however, complete the final transition state on the ice surface to produce ethyl chloride. The observation gives evidence that the electrophilic addition reaction of ethene occurs through an ethyl‐like intermediate with an ionic character.     

超声波辅助离子液体顶空液相微萃取-气相色谱-质谱法测定水中多氯联苯

以离子液体1-丁基-3-甲基咪唑-六氟磷酸盐(简写作[C_4MIM][PF_6])为萃取剂,取水样10mL,加入氯化钠0.15g,待溶解完全后调节其酸度为pH 5.0,用悬挂在微量进样器针端的一滴[C_4MIM][PF_6](1μL)在室温下超声萃取28 min。将萃取了多氯联苯(PCB's)的离子液体液滴在内径扩大至3.5mm的内衬管的气化室内,于280℃解吸1min,即进入毛细管柱进行色谱分离后进行质谱测定。PCB's的线性范围为10～300ng·L~(-1),检出限(3S/N)在1.2～2.3ng·L~(-1)之间。分析了8个海水样品,并用标准加入法做回收试验,测得回收率在81.5%～104.2%之间。     

海地瓜多糖脱色工艺研究

比较了活性炭、H2O2及大孔树脂对海地瓜多糖的脱色效果。从脱色率及多糖保留率两方面进行考察,树脂D392处理优于活性炭和H2O2,对其脱色工艺进行优化,通过响应面实验建立了数学模型,并确定树脂D392脱色的最优工艺为时间:5h,pH 10,温度:60℃,此时,脱色率达(84.2±0.6)%,多糖保留率为(82.9±1.1)%。研究工作有利于海参多糖品质的提高,为海参多糖后续研究及应用奠定了基础。     

磷酸锡晶体去除海水中Pb(Ⅱ)研究

利用合成的磷酸锡晶体作为吸附剂,考察了pH值、吸附时间、初始浓度、温度等因素对吸附水溶液中Pb2+的影响,同时考察了在模拟海水中的吸附效果。结果表明,磷酸锡对Pb2+的吸附量随着pH(3~6)以及吸附时间的增大而增加。吸附动力学过程符合准二级动力学模型。等温吸附数据用Langmuir方程拟合效果最好,20℃时饱和吸附量达到110.50mg/g。Dubinin-Radushkevich(D-R)模型研究表明吸附机理属于化学离子交换。反应机理为磷酸锡中的H+与溶液中的Pb2+发生了离子交换反应。热力学研究表明磷酸锡对Pb2+的吸附是一个自发的、吸热的过程,升温有利于吸附。模拟海水中Pb2+的吸附实验结果表明,高盐度对磷酸锡吸附Pb2+有一定的不利影响,但幅度不大,可以用于去除养殖海水中的Pb2+。所吸附的Pb2+可以用HCl解吸,说明磷酸锡具有重复利用的潜能。     

Diffraction and external reflection by dielectric faceted particles

The scattering of light by dielectric particles much larger than the wavelength of incident light is attributed to diffraction, external reflection and outgoing refracted waves. This paper focuses on diffraction and external reflection by faceted particles, which can be calculated semi-analytically based on physical optics. Three approximate methods; the surface-integral method (SIM), the volume-integral method (VIM), and the diffraction plus reflection pattern from ray optics (DPR) are compared. Four elements of the amplitude scattering matrix in the SIM and the VIM are presented in an explicit form. Of interest is that diffraction and external reflection are separable in the SIM, whereas they are combined in the VIM. A feature of zero forward reflection is noticed in the SIM. The applicability of the DPR method is restricted to particles with random orientations. In the manner of van de Hulst, we develop a new technique to compute the reflection pattern of randomly oriented convex particles using spheres with the same refractive index, resulting in an improvement in the precision of the reflection calculation in near-forward and near-backward directions. The accuracy of the aforementioned three methods is investigated by comparing their results with those from the discrete-dipole-approximation (DDA) method for hexagonal particles at the refractive index of 1.3+i1.0. For particles with fixed orientations, it is found that the SIM and the VIM are comparable in accuracy and applicable when the size parameter is on the order of 20. The ray-spreading effect on the phase function is evident from the results of various size parameters. For randomly oriented particles, the DPR is more efficient than the SIM and the VIM.     

Toward a new elastic-decohesive model of Arctic sea ice

This paper argues for a new constitutive model, an elastic-decohesive model for sea ice. The model is motivated by examining satellite observations of the Arctic processed to show ice deformation in the form of divergence, shear and vorticity. The model is implemented numerically in the material-point method and used to predict motion and deformation of sea ice by simulating a region of the Beaufort Sea. The model is able to capture the qualitative and statistical behavior of localized deformation seen in the observations.