畜禽副产物腥味形成机制及脱腥方法研究进展

畜禽副产物是指畜禽屠宰后除胴体肉外的可食性部分,含有丰富的蛋白质、脂肪、碳水化合物、矿物质、维生素等营养物质,但其腥味问题严重阻碍了深加工和高值化利用,造成极大的资源浪费和严重的环境污染,限制了畜禽肉制品加工行业的发展。近年来,针对畜禽副产物的脱腥方法不断被开发和探索,成为畜禽副产物加工的研究热点。本文综述了畜禽副产物中腥味物质的来源和产生机制,介绍了物理法(感官掩蔽法、吸附法、包埋/微胶囊法、其他物理脱腥方法)、化学法(酸碱盐处理法、天然抗氧化剂法、氧化剂法、美拉德反应法)、生物法(酵母发酵法、其他微生物发酵法)和复合法等脱腥方法,以期为畜禽副产物脱腥方法开发和综合利用提供理论指导。     

A library of carbon-supported ultrasmall bimetallic nanoparticles

Small-sized bimetallic nanoparticles that possess numerous accessible metal sites and optimal geometric/electronic structures show great promise for advanced synergetic catalysis but remain synthetic challenge so far. Here, an universial synthetic method is developed for building a library of bimetallic nanoparticles on mesoporous sulfur-doped carbon supports, consisting of 24 combinations of 3 noble metals (that is, Pt, Rh, Ir) and 7 other metals, with average particle sizes ranging from 0.7 to 1.4 nm. The synthetic strategy is based on the strong metal-support interaction arising from the metal-sulfur bonding, which suppresses the metal aggregation during the H₂-reduction at 700 °C and ensure the formation of small-sized and alloyed bimetallic nanoparticles. The enhanced catalytic properties of the ultrasmall bimetallic nanoparticles are demonstrated in the dehydrogenation of propane at high temperature and oxidative dehydrogenations of N-heterocycles.

     

Tribological behaviours of an ion sulphurisation layer on steels

A sulphide layer with a certain thickness was made on the surface of 1045 and 52100 steels by means of a low temperature ion sulphurisation process. Tribological behaviours of the sulphide layers were investigated on a SRV reciprocating wear tester under dry and paraffin oil lubrication conditions. SEM equipped with EDX was used to analyse the morphologies and compositions of wear scars and wear debris. Sulphide layers showed remarkable friction-reducing effects and obvious wear-resistance. With the increase in thickness of the sulphide layer, its operational period was extended, but its friction coefficient was unchanged greatly. Under the same experimental conditions, the operational period of the sulphide layer on 52100 steel was longer than that on 1045 steel, and the wear-resistance of the former was better. The wear mechanism of the sulphurised surface is discussed.     

Structure and friction-reducing property of the sulfide layer produced by ion sulfuration

Sulfide layers with a certain thickness were made on the surface of 1045 and 52100 steels by means of the low-temperature ion sulfuration technique. Metallography, scanning electron microscope (SEM) + energy-dispersive x-ray analysis (EDX), and x-ray diffraction (XRD) were adopted to analyze the structure of sulfide layers; the tribological properties of the layers lubricated by paraffin oil were also investigated on a reciprocating tester. The results showed that sulfide layer is porous, and its structure is mainly composed of FeS, FeS₂, and substrate phases. The sulfide layer possessed a remarkable friction-reducing effect; its friction coefficient was lower on average, by about 50%, than that of the surface without layer. With the increase of layer thickness, its friction coefficient was unchanged, and under low load conditions, its operational period was prolonged. Under the same experimental conditions, the operational period of sulfide layer on 52100 steel was longer than that on 1045 steel, and its friction coefficient was lower as well.     

Porous carbon nanofibers with narrow pore size distribution from electrospun phenolic resins

Phenolic resin-based porous carbon nanofibers (PCNFs) with large surface area and narrow pore size distribution have been successfully prepared using novolac-type phenolic resin as precursor. The high molecular weight precursor was first synthesized in this study, then was dissolved in methanol. The PCNFs were finally obtained through electrospinning the phenolic resin polymer solution followed by successive curing and carbonization without activation. The N₂ adsorption/desorption isotherms reveal that the PCNFs have high specific surface area about 812 m²/g, the pore size falls in the range of 0.4-0.7 nm and the pore volume is 0.91 cm³/g. The vapor adsorption testing demonstrated that PCNFs exhibited different adsorption performance for ethanol and water.     

电热冲击对多物理场耦合烧结收缩致密化的影响

多物理场耦合烧结是一种粉末材料低温烧结快速致密化的新方法,为研究快速升温过程中的电热冲击对多物理场耦合烧结收缩及致密化的影响,以纯Fe粉为研究对象,利用Gleeble-1500D热模拟机,将Fe粉压坯以50℃/s的升温速度快速加热至825℃,不保温,然后冷却至400℃,随后分别以相同的升温速度和冷却速度在400℃至825℃的范围内共进行5次电热冲击,并与传统真空烧结法进行了烧结致密化对比。研究发现,多物理场耦合烧结时在快速升温的电热冲击过程中压坯在较低温度时即出现急剧收缩,在825℃的最高温度下经过2分钟的电热冲击循环,粉末压坯即实现了烧结致密化,烧结体的相对密度为97.55%;而传统真空烧结时,在1125℃的烧结温度保温60分钟,烧结体的相对密度为85.70%。结果表明,与传统的高温长时间的烧结保温方式相比,多物理场耦合烧结的电热冲击方式是实现粉末材料快速烧结致密化的一条新途径。     

热电池用氮化硼纤维基复合隔膜的研制及性能研究

以氮化硼纤维平纹布为载体,用前驱体转化法在平纹布内部均匀复合纳米氧化镁颗粒,制备出了氮化硼纤维基复合隔膜。用SEM、厚度测试、热处理、TG-DSC、电解液吸附能力测试等手段研究了复合隔膜的结构、稳定性及电解液吸附能力。研究表明:所制备的复合隔膜结构致密,厚度为300μm左右,内部均匀复合纳米氧化镁颗粒,具有良好的高温稳定性能。复合处理工艺能够显著提高隔膜的电解液吸附能力和保持能力,电解液吸附率达160%以上。     

A Novel Heterostructure Based on RuMo Nanoalloys and N-doped Carbon as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Heterostructures exhibit considerable potential in the field of energy conversion due to their excellent interfacial charge states in tuning the electronic properties of different components to promote catalytic activity. However, the rational preparation of heterostructures with highly active heterosurfaces remains a challenge because of the difficulty in component tuning, morphology control, and active site determination. Herein, a novel heterostructure based on a combination of RuMo nanoalloys and hexagonal N-doped carbon nanosheets is designed and synthesized. In this protocol, metal-containing anions and layered double hydroxides are employed to control the components and morphology of heterostructures, respectively. Accordingly, the as-made RuMo-nanoalloys-embedded hexagonal porous carbon nanosheets are promising for the hydrogen evolution reaction (HER), resulting in an extremely small overpotential (18 mV), an ultralow Tafel slope (25 mV dec⁻¹), and a high turnover frequency (3.57 H₂ s⁻¹) in alkaline media, outperforming current Ru-based electrocatalysts. First-principle calculations based on typical 2D N-doped carbon/RuMo nanoalloys heterostructures demonstrate that introducing N and Mo atoms into C and Ru lattices, respectively, triggers electron accumulation/depletion regions at the heterosurface and consequently reduces the energy barrier for the HER. This work presents a convenient method for rational fabrication of carbon–metal heterostructures for highly efficient electrocatalysis.