卧螺离心机的减振降噪技术研究

针对离心机在高速回转中完成非均相分离和过滤工作时,振动和噪声问题非常突出,除了影响机械本身的使用性能和年限,还会对人体健康和环境造成危害,以用于酒糟液脱水分离的LW-380D型并流型卧式螺旋卸料沉降离心机为研究对象,采用谱分析、声强测量分析、试验模态分析等测试分析技术对离心机进行振动和噪声分析诊断,找出产生振动和噪声的原因,并采取相应的减振降噪控制措施。机组噪声声功率级由104.9 dB(A)降至98.7 dB(A);声压级由91.0 dB(A)降至84.4 dB(A);振动烈度由11.2降至4.5以下,达到了允许的噪声和振动标准要求,提高了产品质量和技术水平,可为离心机的减振降噪及结构优化设计提供指导。     

Effects of simulated digestion in vitro on cell wall polysaccharides from kiwifruit (Actinidia spp.)

Cell wall polysaccharides are resistant to digestion and absorption in the human small intestine and are considered to be delivered to the colon in a chemically unaltered state. In this paper, pulp from green and gold kiwifruit was subjected to in vitro upper-intestinal tract digestion and the chemical and physical changes to cell wall polysaccharides (dietary fibre) were investigated. Yields of insoluble fibre decreased slightly with simulated digestion while soluble fibre yields increased. Constituent sugar and glycosyl linkage analysis of the soluble and insoluble fibre fractions revealed that the chemical composition and structure of the non-starch polysaccharides remained largely unchanged. However, the degree of methylesterification of galacturonic acid residues present in the pectin-rich soluble fibre fractions of both fruit decreased with treatment; size-exclusion chromatography detected changes in the molecular weight profiles of these fractions. These changes may affect the physicochemical properties and fermentability of kiwifruit dietary fibre in the large intestine.     

糖粉分离器的结构优化设计

为了分析糖粉收集过程中,分离器分离效果不佳的现象,采用Fluent软件对糖粉分离器进行仿真分析。基于现有结构,分别改变分离器出口结构、增加分离器高度、减小分离器筒径、筒内装置螺旋导流叶片,比较不同结构对分离器分离效果的影响,并讨论了进风方式对分离器分离效果的影响。研究结果表明,糖粉分离器靠近出口段分离能力较弱,导致风机口糖粉喷出;装有螺旋导流叶片较其他结构更有利于分离能力的提高;进风方式对分离效果有一定影响,采用进口通入空气的方式,比出口抽吸空气的方式分离效果好,但进风方式对糖粉分离器分离能力影响相对较小;带有螺旋导流叶片的糖粉分离器更加适合糖粉的收集与分离。     

马铃薯蛋白酶抑制剂酶解产物超滤组分的抗氧化活性与结构特征

本实验以马铃薯蛋白酶抑制剂为原料,通过超声联合蛋白酶K酶解处理后,对其酶解产物(PPIHs)的理化性质、抗氧化稳定性及其超滤后各组分的抗氧化活性及结构特性进行分析。结果表明,超声联合酶解处理后,PPIHs的溶解度增加,乳化性和乳化稳定性增强;进一步研究发现,其在80 °C以下的抗氧化稳定性较好,超过80 °C时,有下降趋势;在酸性或中性环境下,除了对ABTS自由基的抗氧化稳定性较差,PPIHs对其他自由基的抗氧化稳定性较好。PPIHs经过超滤得到PPIHs-I(> 10 kDa)、PPIHs-II(3-10 kDa)和PPIHs-III(< 3 kDa)的三种超滤产物,PPIHs-I对ABTS自由基的清除能力最强,Zeta电位的绝对值显著增大;PPIHs-II的油脂氧化抑制能力以及对-OH和DPPH自由基的清除能力较强,粒径均显著减小。通过紫外吸收光谱、傅里叶变换红外光谱和荧光光谱中可以看出,酶解产物的结构发生明显改变,如无规卷曲和β-转角相对含量提高,β-折叠含量和 α-螺旋相对减少,疏水性增强等,进而改善其抗氧化活性。     

蛹虫草免疫调节蛋白分离纯化、结构表征与免疫调节活性研究

目的 探究蛹虫草蛋白质的免疫调节活性和一级结构。方法 过碱溶酸沉法提取蛹虫草蛋白质,并且用阴离子交换层析法和葡聚糖凝胶层析法对其进行分离纯化,获得一种免疫调节效果较好的组分(记为CMP 2b),通过建立小鼠巨噬细胞免疫调节模型对其组分进行活性评价得到活性最佳的组分,通过基质辅助激光解吸飞行时间质谱测得其分子量大小,通过蛋白质谱解析出其蛋白质一级结构。通过小鼠巨噬细胞研究其对巨噬细胞RAW264.7增殖活性、吞噬率、一氧化氮(nitrogen monoxide, NO)分泌量、免疫因子白细胞介素-1β (interleukin-1β, IL-1β)、免疫因子白细胞介素-6 (interleukin-6, IL-6)、干扰素-γ (Interferon-γ,IFN-γ)和肿瘤坏死因子-α (tumor necrosis factor-α, TNF-α)释放量等方面。结果 通过阴离子交换色谱和葡聚糖凝胶色谱分离纯化出一种蛹虫草免疫调节蛋白CMP 2b,由蛋白质谱测得它由196个氨基酸组成,分子量为22.460 kDa;通过建立巨噬细胞免疫调节模型,研究得出CMP 2b对巨噬细胞的增殖能力、吞噬能能力有显著提高,细胞增殖率最高达到了空白对照组的152.91±5.55%,吞噬能力提高了23.34%;并且促进巨噬细胞分泌NO、ROS、IL-1β、IL-6、IFN-γ及TNF-α,其中NO分泌水平分别达到了空白对照组的2.31倍,ROS 分泌水平达到阳性对照组 LPS的 82.33%,TNF-α、IL-1β、IFN-γ和IL-6分泌量分别为空白对照组的5.51倍、17.42 倍、4.18倍和26.75 倍,显著增强了巨噬细胞免疫调节能力。     

Characterization of Physical Properties of Flour and Starch Obtained from Gamma‐Irradiated White Rice

Physical and structural characteristics of rice flour and starch obtained from gamma‐irradiated white rice were determined. Pasting viscosities of the rice flour and starch, analyzed by using a Rapid Visco Analyser, decreased continuously with the increase in irradiation dosage. Differential scanning calorimetry showed that gelatinization onset, peak and conclusion temperatures of rice flour and starch changed slightly but the enthalpy change decreased significantly with increase of irradiation dosage. All irradiated starch displayed an A‐type X‐ray diffraction pattern like the native starch. Gel permeation chromatography showed that the blue value ratio of the first peak (amylopectin) to the second one (amylose) decreased with the increase of the irradiation dosage. The weight‐average molecular weight (M_w) and gyration radius (R_z) of amylopectin analyzed by using HPSEC‐MALLS‐RI (high‐performance size‐exclusion chromatography equipped with multiangle laser‐light scattering and refractive index detector) decreased gradually from 1.48×10⁹ (M_w) and 384.1 nm (R_z) of native rice starch to 2.36×10⁸ (M_w) and 236.8 nm of 9 kGy‐irradiated starch. The branch chain‐length distribution of amylopectins determined by HPAEC‐ENZ‐PAD (high‐performance anion‐exchange chromatography with amyloglucosidase post‐column on‐line reactor and pulsed amperometric detector) showed that gamma irradiation had no significant effect on the amylopectin branch chains with 13≤DP≤24 and 37≤DP, but produced more branch chains with 6≤DP≤12 when the irradiation dosage was less than 9 kGy. It might be deduced that gamma irradiation caused the breakage of the amylopectin chains at the amorphous regions, but had little effects on the crystalline regions of starch granules, especially at low dosage irradiation.     

Structural Characterization of Oat Bran (1→3), (1→4)-β-D-Glucans by Lichenase Hydrolysis Through High-Performance Anion Exchange Chromatography with Pulsed Amperometric Detection

Cereal mixed linkages (1 → 3) (1 → 4)-β-D-glucan is a linear polysaccharide composed of glucose units. Oat β-glucan is a natural polymer. The main products of β-glucanase are oligosaccharides with DP3 and DP4, i.e., 3-Ob-cellobiosyl-D-glucose and 3-Ob-cellotriosyl-D-glucose, which represent over 90% of the molecule. Keeping in mind all the benefits of oat bran, the present study was planned to investigate the structural properties of oat bran, high-performance anion exchange chromatography with pulsed amperometric detection was used to examine these oligosaccharides. The structural analysis of oat bran of two oat varieties revealed that the ratio of soluble and insoluble triose to tetraose in β-glucan fraction was 1.44 and 1.78, respectively, for Avon variety; while the ratio of soluble and insoluble triose to tetraose in β-glucan fraction for Sargodha-81 was 1.49 and 1.77. The major units determined were cellotriose and cellotetraose. Other units cellopentaose and hexaoses were also existed but in minor fractions. Lichenase hydrolysis high-performance anion exchange chromatography with pulsed amperometric detection appeared to be the best choice for structural analysis of purified samples of mixed-linkage β-glucan.     

浅谈一片袖的结构变化及在丝绸服装上的应用

分析了一片袖结构造型与人体胳膊的关系和一片袖结构最基本的变化,以及一片袖结构的分解重组给袖型结构带来的立体感和艺术感,论述了多种类型的一片袖结构在丝绸服装上的应用。