Improving gelling properties of myofibrillar proteins incorporating with cellulose micro/nanofibres

The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.     

Efficient utilization of silanol group in rice husk to promote the synthesis of Ni-phyllosilicate for CO2 methanation

It is a challenge to prepare Ni-phyllosilicate catalysts deriving from the reaction of nickel salts and biomass-based silica with high Ni contents. In order to efficiently synthesize nickel phyllosilicate, the acid-treated rice husk without calcination (P-R) was directly used as the raw material. The as-synthesized Ni-phyllosilicate (N/P-R) exhibited high nickel content of 46.7 wt% owing to utilization of the abundant silanol group in the fresh rice husk. On the contrary, the Ni content of Ni-phyllosilicate sample (N/R–S) prepared using the calcinated rice husk-based silica was only 4.8 wt% because of the loss of silanol group during calcination process. As a result, N/P-R displayed much higher catalytic activity for CO₂ methanation than N/R–S. It was found that the silanol group was in favour of forming the important intermediate Si(OH)₄, and thereby facilitated the formation of nickel phyllosilicate. In addition, the N/P-R catalyst demonstrated superior stability and excellent anti-sintering ability in the long lifetime test. In short, the proposed method in this work could not only efficiently synthesize nickel phyllosilicate with high Ni content, but also reduce energy consumption and operation steps compared to the one prepared using biomass-based silica.     

二甲基二氯硅烷水解反应器研究进展

基于对甲基氯硅烷单体生产中水解反应特点的分析,论述了国内外几种水解反应器的结构特点,着重介绍了几种水解反应器在工业应用过程中存在的优缺点,并对水解反应器未来的发展方向进行了展望。     

复杂炼油塔模拟的改进联立方程内外层算法

在内外层算法的基础上，采用联立方程思想将主塔、侧线汽提塔视为一个整体进行建模，并针对复杂炼油塔的特点对算法提出了改进。首先，由于传统内外层法简化的K值模型对组成的变化不敏感，在处理带有石油的体系时，容易出现迭代次数较多，甚至部分塔板温度更新异常的问题，因此采用了汽相分数加和式推导了简化的K值模型加权因子。其次，借鉴流量加和法思想，规定侧线汽提塔的塔底产品流量作为设计变量，增强了算法收敛的稳定性。为验证改进后算法的有效性，采用不同的算法对实际的常压塔进行了模拟，结果显示改进后的算法适合应用于复杂炼油塔的模拟计算。     

Low shear rheological behaviour of two-phase mesophase pitch

The low shear rate rheology of two phase mesophase pitches derived from coal tar pitch has been investigated. Particulate quinoline insolubles (QI) stabilised the mesophase spheres against coalescence. Viscosity measurements over the range 10–10⁶ Pa s were made at appropriate temperature ranges. Increasing shear thinning behaviour was evident with increasing mesophase content. At low mesophase contents the dominant effect on the near Newtonian viscosity was temperature but at higher contents it was the shear rate; temperature dependence declined to near zero. The data indicated that agglomeration could be occurring at intermediate mesophase volume fractions, 0.2–0.3. The Krieger–Dougherty function and its emulsion analogue indicated that in this region the mesophase pitch emulsions actually behaved like ‘hard’ sphere systems and the effective volume fraction was estimated as a function of shear rate illustrating the change in extent of agglomeration. At the higher volume fractions approaching the maximum packing fraction, which could only be measured at higher temperatures, the shear thinning behaviour changed in character and it is considered that this is possibly due to shear induced deformation and breakup of dispersed drops in the shear field.     

Ni-Foam Structured Ni-Phyllosilicate Ensemble as an Efficient Monolithic Catalyst for CO2 Methanation

This work proposed a new path to synthesize Ni-phyllosilicate through the reaction of nickel hydroxide and silica sol on the surface of Ni-foam to form the monolithic Ni-phyllosilicate/Ni-foam catalyst. Ni-phyllosilicate could reprint the morphology of nickel hydroxid and firmly anchor on the framework of Ni-foam, which obtained fine Ni particles of 2.8 nm after reduction in H₂ at 650 °C, resulting in high catalytic activity for CO₂ methanation. In addition, the Ni-phyllosilicate/Ni-foam catalyst showed high long-term stability in a 100 h-lifetime test owing to the combined effects of surface confinement of Ni-phyllosilicate, firm anchoring between Ni-phyllosilicate and Ni-foam, as well as the high heat transfer property of Ni-foam.

Graphical Abstract

     

胶片导切机旋转刀的有限元分析

基于有限元分析方法,对密炼机上辅机系统的胶片导切机旋转刀刀片强度进行分析,并根据分析结果优化旋转刀刀片的结构设计和材料选择。结果表明:传统机械破碎强度(P_b)理论不适用于胶片导切机旋转刀的胶片切割;在剪切力(F_2)一定的条件下,减小胶片导切机旋转刀刀片安装偏角或者增大刀刃宽度(W)可以降低旋转刀刀片的应力,从而减少刀片崩裂,延长刀片的使用寿命,也可以通过更换材料和改变热处理的方法来降低刀片制造成本;在F_2和P_b一定的条件下,适当增大W可以减小胶片导切机投产后的磨刀频率,降低维护成本。     

Protein hydrolysates from animal processing by-products as a source of bioactive molecules with interest in animal feeding: A review

Industrial processing of livestock, poultry and fish produces a large amount of waste in a solid or liquid form that can either be destroyed or be used to make compost, biogas or other low-added value products. However, the by-products from animal processing industries have a potential for conversion into useful products of higher value, such as protein hydrolysates, with interesting applications in animal feed. Low amounts of animal protein hydrolysates included in aqua-feeds may enhance growth rate and feed conversion of farmed fish and crustacean. Animal protein hydrolysates may also be incorporated in diets to enhance the nonspecific immunity of fish. As well, these hydrolysates can be used as a good source of amino acids for newly weaned animals. Protein hydrolysates from animal by-products including antimicrobials, antioxidants, opioid-like and/or other interesting bioactive molecules have promising and interesting applications on companion and production animals. By-products from animal processing industries are therefore a promising source of bioactive peptides of considerable interest for animal care, always within the framework of the existing legislation. Possible drawbacks and future trends of the use of animal by-products and/or production of protein hydrolysates from those materials are also discussed.     

Prevalence,enumeration, and characterization of Salmonella isolated from aquatic food products from retail markets in China

This study aimed to estimate the extent and level of Salmonella contamination of aquatic food products in China, and to determine serotype, virulotype, and the antimicrobial resistance profiles of recovered Salmonella isolates. Out of 554 samples collected from July 2011 to May 2014, 86 (15.5%) tested positive for Salmonella. The highest contamination rate occurred in oysters (23.1%, 6/26), followed by freshwater fish (18.6%, 43/231), shrimp (13.0%, 13/100), and saltwater fish (12.2%, 24/197). The contamination levels generally corresponded to a most probable number (MPN)/g of 0.3–10, although one sample exceeded 110 MPN/g. Among the 103 isolates, S. Typhimurium, S. Wandsworth, S. Thompson, and S. Derby were the most prevalent serovars. Sixty-eight isolates (66.0%) were resistant to at least one antimicrobial, and 35 (34.0%) were resistant to more than three. High rates of resistance were observed for tetracycline (35.9%), ampicillin (28.2%), nalidixic acid (26.2%), trimethoprim-sulfamethoxazole (25.2%), chloramphenicol (20.4%) and streptomycin (18.4%). Of note, S. Thompson isolates exhibited resistance to multiple extended-spectrum cephalosporins, ciprofloxacin, and other antimicrobials. PCR analysis of 15 virulence genes showed that ssaQ, mgtC, siiD, sopB, and bcfC were present in all 103 isolates, whereas the remaining loci were variably distributed. S. Typhimurium, S. Enteritidis, and S. Weltevreden isolates exhibited a wider range of pathogenicity determinants compared with the other strains. Our study provides a comprehensive surveillance on prevalence of Salmonella in aquatic food products from China and indicates its potential risk to public health. These data are valuable for epidemiological studies, risk management, and public health strategies.     

基于最小维修的石化安全设备区间截尾寿命数据分析

在石化安全关键设备寿命截尾数据的可靠性评估过程中，为避免传统可靠性评估方法未考虑维修对故障间隔时间的影响，以及中值填充法误差较大的缺点，本文提出了一种逆变换区间截尾数据填充方法。首先，在可修系统基于最小维修的假设下，通过非齐次泊松过程描述系统的故障趋势，利用逆变换填充得到监测区间的缺失数据；随后根据蒙特卡罗期望最大化算法，获得填充数据的参数估计值。通过蜡油加氢装置紧急泄压阀的案例分析，该算法能够很好地融合已有数据，得到的形状参数估计值偏差与中值填充法相比缩小4%以上，从而验证了该算法的有效性；这有助于安全关键设备的定量化完整性管理，保障石化装置平稳运行。