Effect of microwave heating time on the gel properties of chicken myofibrillar proteins and their formation mechanism

The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties.     

Gelling behavior of MgAl2O4 slurries with a common dispersant

MgAl₂O₄ transparent ceramics were shaped by a commonly used polyacrylic acid (PAA), which acted as both dispersant and gelling agent. The spinel slurries were prepared by ball-milling MgAl₂O₄ powder, PAA, and water in an attrition mill. The gelling of slurries happened at room temperature in air atmosphere without any other organic additive. The gelling mechanism was the formation of chelates between Mg²⁺ and carboxyl groups (-COO⁻) of PAA. The frequency-based testing method was applied to investigate the gelling process of the as-prepared slurry. In addition, a novel in situ characterization method based on a modified indentation testing was invented to better understand the strengthening of the wet green body with time and to guide when demolding could be carried out. After sintering, transparent MgAl₂O₄ ceramics with high in-line transmittance were resulted.     

Layered ceramics based on InGaO3(ZnO)2: Preparation and experimental investigation of high-temperature heat capacity and thermal conductivity

This paper reports on a method for producing ceramics from a high-purity, submicron InGaO₃(ZnO)₂ powder synthesised using a PVA-assisted gel combustion method, as well as an experimental study of the thermophysical properties of the ceramic materials obtained. The platelet-like crystallites of the InGaO₃(ZnO)₂ obtained were several microns long and up to several hundred nanometres thick. Layered ceramics obtained by sintering compacted InGaO₃(ZnO)₂ powders at temperatures of 1373–1773 K had a bulk density that was 68–96 % of the theoretical density. The temperature dependence of heat capacity in the range 306–1346 K was studied experimentally for InGaO₃(ZnO)₂ using the DSC method. It was found that, in the range 323–1173 K, layered InGaO₃(ZnO)₂ ceramics had a low thermal conductivity, which decreased from 2.0–1.3 W/(m K. The results obtained make it possible to consider this material as a promising thermal barrier coating.     

Size-dependent separation of graphene oxide by deformation of packed-gel in a chromatographic column

ABSTRACT

A deformable gel-packed chromatographic column was used to separate as-synthesized graphite oxide with different sizes. The synthesized gel (56 µm) was deformed by pressure of the fluid flow and the gaps in the gels showed a range of sizes. A suspension of graphene oxide (0.1 g/L, 10 mL) was injected, and graphene oxide in the elution had a size at 0.56 μm and 0.14 μm, whereas in half upper and bottom domain of the gel layer graphene oxide had a size at 33 µm and 2.9 µm, respectively, demonstrating that graphene oxide suspension was separated by size through gel layer.     

Structures and properties of chicken myofibrillar protein gel induced by microwave heating

Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics.     

Photochemical Reactions in Supramolecular Assemblies of Gels: Dimerizations and Polymerizations via Pericyclic Reactions

Gel state reactions offer new direction for the reactivity of the organic molecules or metal‐organic materials upon photoirradiation with shorter reaction times and high yields compared to solid and solution states. The restricted molecular movement among the molecules in the soft solids control the stereoselectivity of the photoproducts in the gel state reactions. To date, most of the strategies based on self‐assembly have been demonstrated in the solid state, in particular for [2+2] reactions of olefins and polymerization reactions of diacetylenes via 1,4 addition. The soft materials are of emerging materials in recent days given their many applicative day‐to‐day aspects. This review gives a glimpse of recent reports on pericyclic reactions in the gel state that are designed based on the self‐assembly concept. Also it highlights how such reactions accompany the physical changes in the structure of the gels and stereo controlled products with high yields.     

Na2O—B2O3—SiO2—KH560系统凝胶及其涂层性能研究

用溶胶凝胶法研究了Ｎａ２ＯＢ２Ｏ３ＳｉＯ２ＫＨ５６０无机有机复合涂层胶凝过程，测定了溶胶的粘度，用ＤＳＣ，ＴＧ，ＸＲＤ，ＩＲ，ＳＥＭ分析了凝胶的物相和结构，目测并在ＳＥＭ下观察了这种胶凝材料涂覆在水泥砂浆表面后的表观性能，分析了影响这些性能的因素．在无机Ｎａ２ＯＢ２Ｏ３ＳｉＯ２三组分系统中掺加有机改性剂ＫＨ５６０，无机相和有机相之间以化学键形式结合，形成无机有机互穿的杂化结构．经１３０°Ｃ低温处理即能制备出致密、不开裂，且具有良好物化特性的无机有机涂层材料．影响涂层性能的因素主要有ＫＨ５６０掺量、涂层液粘度、热处理制度（包括加热制度和冷却制度）等     

全自动血库系统的研制

全自动血库系统针对血型鉴定方法做出了重大改进。传统血型鉴定方法主要包括玻片法和试管法。如今越来越多的使用微柱凝胶法,但是从加样到判读的整个过程都需要人工操作,不仅难以实现规范化和标准化,而且严重影响判读结果的准确性和可靠性。通过对上述问题的仔细研究,设计开发了全自动血库系统。全自动血库系统包括卡片集装孵育系统、卡片抓取及运输系统、离心系统和照相扫描判读系统,不仅可以实现血型鉴定的自动化,而且可以保存判读结果,为该领域的规范化、自动化提供了极大的发展空间。     

一种评价特种凝胶ZND启动压力的新仪器

针对漏失及恶性漏失的堵漏工作,研制的特种凝胶ZND在实际应用中取得了显著的成绩,但是对于恶性漏失堵漏用的凝胶,没有一套合适的仪器及方法来规范其性能指标,因此研制了一台具有高精度的新型启动压力装置,并得到了相关的启动压力评价方法——液位-压力曲线。通过液位-压力曲线,可以确定凝胶在模拟地层中的启动压力,并能够判断相同启动压力情况下凝胶的性能优劣。     

Investigation of injectable drospirenone organogels with regard to their rheology and comparison to non-stabilized oil-based drospirenone suspensions

The objective of this study was to evaluate organogels as potential injectable drug-delivery systems for drospirenone (DRSP). Recently, studies on organogel characterization with focus on the parenteral injection are rarely to find in the literature. DRSP organogels contained the drug suspended in medium-chain triglycerides and were stabilized by various organogelators. The DRSP organogels were assessed in comparison to non-stabilized DRSP microcrystal suspensions (MCSs). Furthermore, rheological properties of the organogels, in particular the elastic modulus (G′), the complex viscosity (η*) and the elasticity, were evaluated with respect to the long-term stability, syringeability/injectability and in vitro release. DRSP organogels showed significantly improved storage stability compared to non-stabilized MCSs with regard to sedimentation and particle growth. Furthermore, all of the DRSP organogels showed shear-thinning behavior. Thus, ejection from syringes was possible by an autoinjector using 23G needles comparable to non-stabilized MCSs. Nevertheless, DRSP organogels exhibited significantly more sustained drug release than non-stabilized MCSs most likely caused by partial recovery of the organogelator structures at 37?°C after destruction. Consequently, DRSP organogels were evaluated to be superior to conventional non-stabilized MCSs. Silica organogels, which provided the highest elasticity, moderate G' and η* and avoided most efficiently particle growth, are slightly more preferable compared to the other DRSP organogels.