Antimicrobial and antioxidant activities of different propolis samples from north‐western Algeria

The aim of this study was the investigation of antimicrobial and antioxidant activities of different ethanolic extracts of propolis (EEP) collected from north‐western Algeria. Total polyphenols and flavonoids contents of extracts were measured. The UV absorption spectrum showed and confirmed their polyphenols constituents. All EEPs exerted antibacterial activity against Gram‐positive bacteria, but no effect on Gram‐negative bacteria. The minimum inhibitory concentration (MIC) of EEPs ranged from 0.01% to 2.6% v/v. The antioxidant activity was measured using ferric‐reducing power (FRAP), 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical‐scavenging and ESR methods. Propolis TIA‐2 and MOH‐MAS samples showed the highest antioxidative capacity, after 35 min, while TIA‐1, NED‐TL and SFS‐SBA samples showed the highest antioxidative potential of measured EEPs, after 3 min. TIA‐2 sample showed the highest antibacterial, antioxidant activity and highest DPPH free radical‐scavenging activity as well as the highest polyphenols and flavonoids content, compared with other propolis samples.     

Microbiological Quality of Raw Milk and Effect on Quality by Implementing Good Management Practices

Raw milk is a complete food which contains protein, fat, sugars, vitamins and minerals. Even though, raw milk is sterile at secretion, contamination of milk by microorganisms can take place during milk handling, storage and other pre-processing activities. The objectives of this study were to assess the initial microbial load and to determine correlation between Methylene blue dye reduction test with standard plate count method and find possible methods to improve the quality and reduce the wastage of raw milk. As per the records obtain from the chilling centers, about twenty per cent (per month) of raw milk collected to the centers in each district has to be discarded due to spoilage. Out of 13 chilling centers in Kurunagala district, five chilling centers namely Badalgama, Elabadagama, Kuliyapitiya, Dambadeniya and Minuwangoda chilling centers were randomly selected and the initial microbial loads of milk from chilling tanks were tested using Standard Plate Count and Methylene blue dye reduction test. Further, Self- filled questionnaire was used to gather data related to practices in milk supply chain and swab samples were taken from the containers used for milk collection process. Though the microbial population should be below log 6.00 according to the factory standards in Sri Lanka to accept milk for further processing, standard plate count of chilling centers were log 7.08, 6.76, 6.56, 6.70, and 6.88 (CFU/ml) respectively. Good management practices were introduced to rectify the main cause for high microbial counts. After the improvements low microbial counts of above chilling centers were achieved as log 5.91, 5.85, 5.85, 5.86 and 5.94 CFU/ml respectively. Standard Plate Count showed significant difference (p < 0.05) after practicing good management practices. Strong correlation (r² 0.91) was observed between Methylene blue dye reduction test and Standard Plate Counts (log CFU/ml). Therefore, Methylene blue dye reduction test can be used effectively, economically and efficiently, to detect the quality of raw milk and can use as an alternative method for costly and tedious microbiological analysis methods.     

Semi‐volatile organic compounds in heating,ventilation, and air‐conditioning filter dust in retail stores

Retail stores contain a wide range of products that can emit a variety of indoor pollutants. Among these chemicals, phthalate esters and polybrominated diphenyl ethers (PBDEs) are two important categories of semi‐volatile organic compounds (SVOCs). Filters in heating, ventilation, and air‐conditioning (HVAC) system collect particles from large volumes of air and thus potentially provide spatially and temporally integrated SVOC concentrations. This study measured six phthalate and 14 PBDE compounds in HVAC filter dust in 14 retail stores in Texas and Pennsylvania, United States. Phthalates and PBDEs were widely found in the HVAC filter dust in retail environment, indicating that they are ubiquitous indoor pollutants. The potential co‐occurrence of phthalates and PBDEs was not strong, suggesting that their indoor sources are diverse. The levels of phthalates and PBDEs measured in HVAC filter dust are comparable to concentrations found in previous investigations of settled dust in residential buildings. Significant correlations between indoor air and filter dust concentrations were found for diethyl phthalate, di‐n‐butyl phthalate, and benzyl butyl phthalate. Reasonable agreement between measurements and an equilibrium model to describe SVOC partitioning between dust and gas‐phase is achieved.     

4,4′-二氨基二苯醚的快速分析法

在生产工艺稳定的条件下聚酰亚胺薄膜的性能与原材料的质量密切相关。4，4′－二氨基二苯醚是生产均苯型聚酰亚胺的主要原材料之一，论文介绍了一种对其纯度进行快速、简便测定的方法。该方法的准确性、重复性都较好。     

Pd/C催化苯酚氧化羰基化合成碳酸二苯酯反应研究

考察了Pd/C催化苯酚氧化羰基化合成碳酸二苯酯反应,确定了该反应较适宜的反应条件为反应温度80℃、反应压力5MPa、气相反应物进料配比n(CO)/n(O2)=10、反应时间4h。具有较大极性和较强的永久偶极矩的溶剂二氯乙烷的加入可有效提高苯酚转化率和碳酸二苯酯收率。XRD表征表明可能由于水的存在导致催化剂的活性组分Pd发生聚集使晶粒不断增大。     

Corrosion of concrete sewers--the kinetics of hydrogen sulfide oxidation

The widespread occurrence of polybrominated diphenyl ethers (PBDEs) in the environment has attracted considerable attention, leading to concerns about the extent and magnitude of wildlife and human exposure. In this work, we focus on the occurrence and fate of PBDEs in a Norwegian air-plant-herbivore-carnivore system. Specifically, we have analysed for PBDEs in moss, livers from various terrestrial herbivores (moose, grouse, and European roe deer) and, for the first time, livers from the top predator lynx. The samples were collected from different sites and time periods (1990-2004) to identify possible spatial and temporal trends in contaminant levels and patterns. The general finding was that PBDEs were found in all (biotic) samples, although at lower concentrations than previously observed in mammals from the marine environment. The PBDE levels in the herbivores ranged from less than 0.5 ng/g lipid weight to 9.4 ng/g lipid weight as the highest. The median PBDE concentration in lynx was approximately one order of magnitude higher than in the herbivores. In the lynx samples there was a predominance of BDE-153 whereas BDE-47 and 99 dominated in the herbivores. This probably reflects different bioaccumulation properties or metabolic transformation processes of the BDE-congeners, and food choice. Levels of PBDEs in both moss and herbivores showed a general decline towards the northern parts of Norway. No clear temporal trends were observed. The PBDE levels observed in this study were low and are probably of limited toxicological significance.     

铱催化体系不对称合成手性药物中间体

考察了1,1-二苯基丙酮在手性双胺双膦配体与[IrHCl2(COD)]2组成的催化体系下不对称转移氢化合成(S)-(-)-1,1-二苯基-2-丙醇的反应,通过正交实验了考察了反应温度、n(底物):n(铱络合物)、n(铱络合物):n(手性配体)以及n(底物):n(KOH)对反应的影响。结果表明,在异丙醇中,利用该体系催化1,1-二苯基丙酮反应2小时后,反应产率可达97.85%,对映选择性(ee值)达到99.35%     

V-Cu氧化物催化碳酸二甲酯与苯酚酯交换反应

研究了一系列钒-金属复合氧化物对碳酸二甲酯(DMC)和苯酚酯交换合成碳酸二苯酯(DPC)的催化性能,实验结果表明,钒-铜复合氧化物是较好的酯交换合成DPC的催化剂。考察了V/Cu摩尔比,催化剂用量,DMC用量和反应时间对酯交换反应的影响,得到较佳的反应条件： n(V):n(Cu) = 4:1,苯酚用量0.16 mol,V-Cu复合氧化物催化剂的用量为苯酚用量的3.1%（质量比）, n(DMC) : n(苯酚) = 1.5 :1,反应时间9～15 h。在此条件下反应9 h,苯酚的转化率为41.9%,甲基苯基碳酸酯(MPC)及DPC的总收率为40.3%。催化剂重复使用4次后苯酚转化率从41.9%降到29.1%,多次重复使用后的催化剂在空气氛中焙烧即可再生,再生催化剂的催化性能几乎和新鲜催化剂相当,苯酚转化率达到39.8%。     

催化动力学光度法测定痕量铁(Ⅲ)及机制探讨

目的 建立了测定痕量铁的双波长双指示剂催化动力学先度分析的新方法.研究在盐酸介质中,铁(Ⅲ)催化过氧化氢氧化亚甲基蓝使其褪色反应的最佳务件及探讨其反应机制.方法 通过测量催化体系和非催化体系在610 nm和666 nm下吸光度的变化,用双波长指示催化动力学光度法以测定痕量铁(Ⅲ).结果 线性范围为0.2-3.0 μg/25 ml,检出限为9.24×10-11 g/ml.结论 本方法灵敏度高,体系稳定,操作简便,用于实际样品中铁的测定,结果较为满意.     

碳酸二甲酯与苯酚酯交换合成碳酸二苯酯研究

选择Lewis酸催化剂、分子筛催化剂、有机钛和锡化合物催化剂和不同负载型金属氧化物催化剂用于碳酸二甲酯(DMC)与苯酚酯交换合成碳酸二苯酯(DPC)的过程。试验结果表明,：MoO3/SiO2和TiO2／SiO2催化剂对该反应具有相对较好的催化活性和选择性。以MoO3／SiO2为催化剂,DMC转化率和DPC选择性分别为24.3％和37.6％;以TiO2／SiO2,为催化剂,DMC转化率和DPC选择性分别为13.7％和20.0％。在该酯交换反应中,SiO2与Al2O3和MgO相比,是一种良好的催化剂载体。