Comparison and Characterization of Compounds with Antioxidant Activity in Lycium barbarum Using High‐Performance Thin Layer Chromatography Coupled with DPPH Bioautography and Tandem Mass Spectrometry

Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF‐MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2‐O‐β‐d ‐glucopyranosyl‐l ‐ascorbic acid using ESI‐Q‐TOF‐MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity‐based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC‐DPPH bioautography with ESI‐Q‐TOF‐MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum.     

Antimicrobial Effects of Vapor Phase Thymol,Modified Atmosphere,and Their Combination against Salmonella spp. on Raw Shrimp

Salmonella contamination on raw shrimp is a big food safety concern in the United States currently. This research evaluated the inhibition effects of vapor phase thymol, modified atmosphere (MA), and their combination against Salmonella spp. on raw shrimp. Growth profiles of a Salmonella spp. cocktail (6 strains), inoculated onto the surface of raw shrimp, treated with vapor phase thymol at 3 levels (0, 0.8, and 1.6 mg/L), or MA (59.5% CO₂ + 39.5% N₂ + 1% O₂), both alone and in combination, at 3 temperatures (8, 12, and 16 ºC), were determined. Lag time and maximum growth rate of Salmonella spp. under each treatment were obtained using Baranyi and Roberts models. Results indicated that both vapor phase thymol and MA treatments alone inhibited the growth potential of Salmonella spp. effectively, extending the lag time by 10% to 100% and reducing the maximum growth rate by 14% to 71% compared with controlled samples at experimental temperatures (8, 12, and 16 ºC). Combination treatments of vapor phase thymol and MA exhibited greater inhibition effectiveness than each individual treatment and a synergistic antimicrobial effectiveness could be observed on the lag time extension. To the maximum, at 12 ºC, lag time of Salmonella spp. was extended 59.6% more by the combination treatment of 0.8 mg/L thymol + MA (36.97 h) than those effects combined from 0.8 mg/L thymol treatment and MA treatment alone (23.16 h in total). This combination strategy could be potentially utilized for Salmonella inhibition during the long distance and temperature‐abused raw shrimp import process. Practical Application The vapor phase thymol + MA combination strategy could be potentially applied in temperature‐abused and long‐distance raw shrimp import process to retard the Salmonella spp. growth, therefore reducing its import rejection rate as well as enhancing its food safety level to the consumers’ concerns.     

提高陶瓷刀具在干切削加工中性能的方法

陶瓷刀具具有优良的切削性能.本文论述了陶瓷刀具的特点和切削性能,提出了提高陶瓷刀具性能的几种途径,对陶瓷刀具在干切削中的应用进行了分析.     

超声波清洗技术在焊丝生产中的应用

介绍超声波清洗污垢的原理。超声波清洗应用于焊丝镀前处理,可减轻电解碱洗的负担,提高化镀速度。清洗时超声波频率为15~30kHz,声强1~2W/cm2,水做清洗液时温度控制在60℃左右;在焊丝生产线使被淹没的焊丝高于振子表面100mm,超声波清洗宜在敞口容器中进行。     

植物乳杆菌HCS03-001安全性评价及其益生特性分析

为了对植物乳杆菌HCS03-001(CGMCC No.16258)进行安全性评价以及益生特性的研究,通过溶血实验、耐药实验及急性经口毒性实验评价其安全性,通过对酸环境及胆盐环境的耐受性实验、抑菌功能特性实验及通便功效试验评价该菌株的益生特性.结果表明,植物乳杆菌HCS03-001在哥伦比亚血琼脂培养基上无透明圈形成,即...     

GPS系统在玻璃深加工中的运用

李赛克(Lisec)的Glass Processing System GPS系统是结合国内的实际生产经验研发的,可以实现基于GPS系统的高效的中空玻璃深加工,优化玻璃深加工的流程及产品管理.     

Y type zeolites/PI membranes for sulfur-free hydrogen source and for fuel cell applications

Sulfur removal is significant for fuels used as hydrogen source for modern fuel cell applications and to avoid sulfur poisoning of therein used catalysts. Novel membranes for the polymer–zeolite system with well-defined transport channels are proposed for the sulfur removal. Membranes are fabricated using polyimide (PI) as matrix material and Y zeolites as adsorptive functional materials. By detailed analysis of FT-IR, morphology and adsorption performance of membranes, the process-structure-function relationship is obtained. The results show that the functional zeolites particles are incorporated into three-dimensional channels. For all cases, the inlet fuel can be desulfurized to below 0.1 mg L⁻¹, which means that the outlet fuel can be used as sulfur-free hydrogen source for fuel cell applications. The proposed membranes adsorber may be applied as sulfur trap before the reformer for fuel cells on-board or on-site, and it may be applied in a periodically replaceable form. The desulfurization efforts by membrane are likely to play an influential role for the development of sulfur-free hydrogen source and fuel cell area.     

关于高职院校选煤技术课程教学改革的探讨

高职院校以适应社会需求为目标,以培养高素质技能型人才为主线设计培养方案。《选煤技术》课程是研究选煤厂、煤炭加工企业生产一线的技术工作及管理,掌握破碎、重选和浮选等基本技术与相关工序的生产技术和操作技能。本文分析了煤炭深加工与利用专业的发展现状及原因,并结合企业对人才需求量及岗位任职需要的逐渐变化,最后提出了《选煤技术》课程的教学改革途径。     

近红外检测技术的应用

通过对近红外分析技术的研究,论述近红外分析技术的原理及其特点,重点介绍了近红外光谱分析技术在食品分析,药物,水质和烟草等领域的应用。     

塑料管道用料分析

由于塑料管道具有自重轻、耐腐蚀、不污染水质且安装连接较易等优点,在基础设施及建筑领域得到广泛应用。目前,市政给水管、市政排水管、建筑给水管和建筑排水管4类管道在塑料管总量中的占比约为68%。未来几年,加强基础设施建设和棚户区改造,将有力拉动塑料管道需求稳步增长。