食品热物性的多项式数学模型

食品中含有大量的水,食品在冻结阶段水分发生相变,食品中的水分大部分结成冰晶,而水的热物性和冰的热物性有很大的差别,这就导致了食品热物性在冻结过程中发生较大变化,本文阐述了食品热物性模型的重要性,并根据已有的食品热物性经验公式进行编程计算,利用统计分析软件回归分析出食品热物性随温度变化的分段多项式数学模型.     

相变恒温材料六水氯化钙的研究

有关相变恒温材料，目前应用较多的是固液相变材料，而固液相变温度是混合相变材料应用的基础。本文着重研究了以氢氧化钡为成核剂和不同用量的无机相变材料六水氯化钙。利用步冷曲线法测定了添加质量分数分别为1．0％、2．0％和3．O％的氢氧化钡时六水氯化钙的相变温度。测定结果表明3．0％氢氧化钡添加量时，相变效果较好，相变温度为28．10℃。     

如何排除水对氧量计量的干扰

为防止氧分析仪因进水而毁坏，我们在系统中采取了以气水分离为主的除水措施。这样，就妥善地解决了水对氧量计量的干扰。     

探讨沥青路面水损害的防止措施

水损坏已成为沥青路面早期破坏的主方面之一。本文分析了静水和动水对沥青路面的损坏机理,并提出了沥青路面水损坏的防治措施。     

不同冻结速度对猪肉,青鱼肌肉咀嚼性和持水能力的影响

本文以新鲜猪肉、青鱼为原料，研究不同冻结速度对青鱼肌肉、猪肉咀嚼性和持水能力的影响。结果表明：（１）冻结速度对猪肉和青鱼肌肉咀嚼性的影响不显著。（２）冻结速度对不同食品的持水能力具有不同水平的显著影响，新鲜食品的持水能力总是大于冻结后食品的持水能力，冻结速度越快，持水能力减小的程度越小。     

水对沥青路面的影响及病害防治

随着筑路技术的发展，近年来，各种不同类型的沥青混合料以其不同的特点被广泛用于铺筑各级公路路面，使路面使用品质有了很大提高。但由于施工质量问题，水对路面的侵害在一些路段上时有发生，水侵害已成为沥青路面病害产生的主要原因。     

食品工业中的双极膜技术

双极膜是近年来国际上研究比较活跃的一种新型膜．基于双极膜的水解离技术乒逐渐成为一种通用的目标单元操作，可用于多种工业过程，如化工生产、湿法冶金、环境保护和资源回收等领域，并大大地改变了这些领域的面貌．本文针对食品工业领域，介绍了双极膜在食品化工中的应用和研究现状．     

相变储能材料CaCl2·6H2O相变温度调节的实验研究

对添加了少量Ba(OH)2和SrCl2·6H2O稳定剂的相变储能材料CaCl2·6H2O相变温度调节进行了实验研究.研究结果表明:相变储能材料CaCl2·6H2O通过添加过量水的方法能够实现其相变温度的调节,添加过量水的合适范围为0～10％(质量分数),其相变温度调节的合适范围则24.16～28.54℃之间.基于实验结果理论回归得到的相变储能材料CaCl2·6H2O相变温度与添加过量水的关系式,在使用相变储能材料CaCl2·6H2O时,能够对添加不同数量过量水的相变储能材料CaCl2·6H2O之相变温度进行预测.这对于温室的温度控制以及培育优良花卉和特定农作物是非常有用的.     

水活度测量及其溯源性

水活度是食品质量控制中的一个重要指标。通过测定水活度，可有效地评估食品的安全性和稳定性，降低食品水活度，可以延长食品的货架期。本文介绍了几种水活度的测量方法，从水活度的定义探讨了水活度测量的溯源性问题，对于在食品生产、储藏、流通和市场监管等方面水活度的准确测量和监控具有参考意义。     

新型有机-无机复合相变蓄冷材料的制备及性能研究

以六水氯化钙为基材，配备出一种新型复合相变蓄冷材料用于空调蓄冷。该材料的质量配比为81%六水氯化钙+5%乙醇+14%丙三醇。为了降低复合相变材料的过冷度，使用六水氯化铯为成核剂，发现成核剂的添加量为1.0%时过冷度几乎为零。为检验复合相变材料的热稳定性，进行了100次的热循环实验，材料未出现相分层，表明其热稳定性能良好。     

玻璃化转变温度及其对干燥食品加工贮藏稳定性的影响

在玻璃化转变的相关基础理论上 ,综述了影响玻璃化转变温度的主要因素 ,指出了玻璃化转变温度作为建立在动力控制过程的非平衡态基础上的物理化学参数 ,与水分含量和水分活度两重要指标相结合 ,可以用来解释干燥食品加工贮藏中引起食品腐败变质的各种动力学过程     

聚合物中的水

从液体水的结构角度综述了聚合物特别是凝胶中水的状态及聚合物与水的相互作用的最新研究进展。由于采用的实验技术不同以及对聚合物－水相互作用的不同理解,对凝胶中的水状态的看法各异。     

Molecular recognition of alcohol by volume phase transition of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) gel

The swelling behavior of a cross-linked poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) gel in various water/alcohol mixtures was investigated. When the poly(MPC) gel was immersed in various water/alcohol mixtures, a change in the gel volume was observed depending not only on the composition of the alcohol in the mixture but also on the chemical structure of the alcohol. In water/monohydric alcohol mixtures, the poly(MPC) gel had an irregular swelling behavior with a change in the composition of the alcohol, showing the so-called reentrant volume phase transition. These volume phase transition strongly depended on a hydrophobic group, i.e. the polarity of the alcohol. On the other hand, polyhydric alcohol (diol or triol) did not affect the swelling of the poly(MPC) gel even when the composition of the alcohol was changed.

These results suggest that water molecules hydrated on the poly(MPC) chains were withdrawn by hydration of the alcohol molecules and the volume of the poly(MPC) gel decreased. That is in good agreement with the hydration ability of the alcohol and its polarity. Thus, the poly(MPC) gel could recognize a difference in the polarity among the alcohol molecules.     

液相/微胶囊复合体系相变特性实验研究

相变微胶囊材料因其环保性与经济性的优势,已成为相变储能领域的研究热点,但其导热性能过低,严重限制了相变微胶囊材料的推广与应用。本文分别用无水乙醇和蒸馏水填充于微胶囊的颗粒间隙中,获得复合相变体系,研究了无水乙醇和蒸馏水体积分数分别为20.0%、40.0%、60.0%时复合体系相变特性。实验结果表明,相比于空白体系,两液体填充复合体系的相变速率均有明显提高,无水乙醇/微胶囊复合体系相变速率提升了87.5%~266.7%,微胶囊/蒸馏水复合体系提升了125.0%~368.8%。蒸馏水对微胶囊材料的强化效果优于无水乙醇,同时两复合体系的相变速率均随着填充液体体积分数的增加而上升。研究结果对微胶囊相变强化技术的发展提供了理论指导。     

Remarkable difference of phase transition behaviors between Langmuir monolayers and aqueous bilayer vesicles of oligopeptide-carrying lipids

In this research, we synthesized six kinds of oligopeptide-carrying lipids which possessing glycine, diglycine, triglycine, alanine, dialanine, and trialanine residues (see Figure 1 for their formulae), and systematically investigated their phase transition behaviors both at the air-water interface and in aqueous bilayer vesicles. pi-A Isotherms of Langmuir monolayers of these lipids were measured at the air-water interfaces under varied temperature conditions and were analyzed based on compressibility of the monolayers. Above the specific temperature, the transition pressure from its expanded phase to condensed phase is not distinguishable with the collapse pressure of the monolayer, i.e., the monolayer collapses directly from the expanded phase without forming the condensed phase. This temperature was defined as the phase transition temperature of the monolayer, which was compared with the phase transition temperature of the corresponding bilayer vesicle in water. The phase transition temperatures of the oligoglycine-carrying lipids and oligoalanine-carrying lipids are significantly different at the air-water interface, while the corresponding difference is not obvious in their aqueous bilayer vesicles. Consideration based on molecular structures suggests necessity of the water mediation for effective formation of hydrogen bonding between the oligopeptide residues directly connected to dialkyl chains. Therefore, the differences in water accessibility to the films may cause the difference of the phase transition behaviors of the oligopeptide-carrying lipids between the Langmuir monolayers and the aqueous bilayer vesicles. Although the proposed mechanism is not fully supported by experimental evidences, the data presented here clearly demonstrated the presence of significant difference of the phase transition properties between the Langmuir monolayers at the air-water interface and aqueous bilayer vesicles of the oligopeptide-carrying lipids.     

水预冷及卷心菜冷水预冷的应用

水预冷技术在果蔬食品加工或储存中均非常关键。果蔬通过水预冷后，进入冷库储存或下一道加工环节，对于果蔬食品的储存与食物的品质起到明显的效果。本文通过卷心菜水预冷实际生产中的应用案例，简单扼要介绍了水预冷及优缺点、水预冷耗冷量计算及水预冷设计存在的难度和解决办法。     

聚氨酯基pH/温度敏感性水凝胶的结构形态

通过阴离子型端丙烯酸酯基聚氨酯(UAA)与N-异丙基丙烯酰胺(NIPAAm)的共聚交联反应,制备了pH/温度敏感性水凝胶,分析了水凝胶的结构形态及溶胀水的状态.结果表明,凝胶相结构均匀,随聚氨酯含量的降低,凝胶的骨架变得松散,并且孔道结构增大,导致溶胀凝胶中不可冻结水含量及凝胶强度的降低.     

Creating “Smart” Surfaces Using Stimuli Responsive Polymers

Surfaces modified with stimuli‐responsive polymers (SRPs) dynamically alter their physico‐chemical properties in response to changes in their environmental conditions. The triggered control of interfacial properties provided by immobilized SRPs at the solid–water interface has application in the design of biomaterials, regenerable biosensors, and microfluidic bioanalytical devices. In this article, we briefly summarize recent research in this area, followed by two recent examples of research from our laboratory on stimuli‐responsive surfaces. First, we present a new assay to quantify the phase transition behavior of SRPs at the solid–water interface. This assay, which is based on the distance‐dependent colorimetric properties of gold nanoparticles, provides a technically simple and convenient method to determine the effect of different variables on the lower critical solution temperature (LCST) behavior of SRPs at the solid–water interface. Second, we show that stimuli‐responsive surfaces can be created by the immobilization of an elastin‐like polypeptide (ELP), a thermally responsive biopolymer, on a glass surface. We exploit the phase transition of the ELP at a surface to reversibly address an ELP fusion protein to a surface. This method, which we term thermodynamically reversible addressing of proteins (TRAP), enables the reversible, spatio‐temporal modulation of protein binding at the solid‐liquid interface, and will enable the realization of new bioanalytical applications.     

A Double‐Stimuli‐Responsive Fluorescent Center for Monitoring of Food Spoilage based on Dye Covalently Modified EuMOFs: From Sensory Hydrogels to Logic Devices

Unsafe food is a huge threat to human health and the economy, and detecting food spoilage early is an ongoing and imperative need. Herein, a simple and effective strategy combining a fluorescence sensor and one‐to‐two logic operation is designed for monitoring biogenic amines, indicators of food spoilage. Sensors (methyl red@lanthanide metal–organic frameworks (MR@EuMOFs)) are created by covalently modifying MR into ? NH₂‐rich EuMOFs, which have a high quantum yield (48%). A double‐stimuli‐responsive fluorescence center is produced via energy transfer from the ligands to Eu³⁺ and MR. Portable sensory hydrogels are obtained by dispersing and solidifying MR@EuMOFs in water‐phase sodium salt of carboxy methyl cellulose (CMC‐Na). The hydrogels exhibit a color transition upon “smelling” histamine (HI) vapor. This transition and shift in the MR‐based emission peak are closely related to the HI concentration. Using the HI concentration as the input signal and the two fluorescence emissions as output signals, an advanced analytical device based on a one‐to‐two logic gate is constructed. The four output combinations, NOT (0, 1), YES (1, 0), PASS 1 (1, 1), and PASS 0 (0, 0), allow the direct analysis of HI levels, which can be used for real‐time food‐freshness evaluation. The novel strategy suggested here may be a new application for a molecular logic system in the sensing field.     

Mathematical modeling of cold water injection into a depleted high-temperature geothermal reservoir

The injection of cold water into a geothermal reservoir containing superheated vapor is investigated in a one-dimensional approximation. Simplifying assumptions are used for a highly permeable porous medium to derive a self-similar solution and asymptotic estimates for the velocity of boiling front and for the temperature of phase transition. It is demonstrated that the results obtained using a simplified model agree well with the results of numerical simulation using the TOUGH2 computer codes.