Antimicrobial properties of natural substances in irradiated fresh poultry

This study was undertaken to determine if a combined treatment (marinating in natural plant extracts or vacuum) with irradiation could have a synergetic effect, in order to reduce the dose required for complete elimination of Salmonella on fresh poultry. The effect of these combined treatments on the shelf-life extension was also evaluated. The fresh chicken legs were irradiated at 0, 3 and 5 kGy. The poultry underwent microbial analysis(mesophilic and Salmonella detection). For each treatment, the total microbial count decreased with increase of irradiation dose. The marinating treatment have a synergistic effect with irradiation treatment to reduce the total microbial count and controlling the proliferation during storage at 4°C. Irradiation of fresh chicken pieces with a dose of 3 kGy appears to be able to extend the microbial shelf-life by a factor of 2. When the chicken is marinating and irradiated at 3 kGy or when irradiated at 5 kGy without marinating, the microbial shelf-life is extended by a factor of 7 to 8. No Salmonella was found during all the experiment in the chicken in air and marinated. However, a presence of Salmonella was found in samples irradiated at 5 kGy under vacuum, in unirradiated samples and samples irradiated at 3kGy in air and under vacuum.     

微波萃取花生壳天然黄色素及其稳定性研究

对福建产花生壳进行了微波萃取天然黄色素及其稳定性的研究 .研究表明微波萃取的工艺条件是 :以pH =3,体积分数 70 %的乙醇水溶液作提取剂 ,原料与提取剂配比为 1g∶5mL ,微波辐射功率为 12 0W ,辐射时间2 4 0s.对该色素稳定性研究结果表明 ,该色素为水溶性色素 ,属黄酮类色素 ,适用pH值范围比较宽 ,尤其碱性状态效果最佳 ,对光、热稳定性好 ,大多数食品添加剂对色素稳定性影响不大 ,对氧化剂H2 O2 的耐受能力较差 ,对还原剂Na2 SO3 的耐受能力强     

First chemical study of anaspidean Syphonota geographica: structure of degraded sterols aplykurodinone-1 and -2

Two unprecedented degraded sterols, aplykurodinone-1 (1) and -2 (2), have been isolated from the skin of the marine anaspidean Syphonota geographica, collected along the coasts of Greece. The structures and the relative stereochemistry were established by spectroscopic analysis and confirmed by chemical correlation with related known compounds.     

The polysaccharide extracts from the fungi Coprinus comatus and Coprinellus truncorum do exhibit AChE inhibitory activity

The polysaccharide (PSH) extracts from the edible mushroom species Coprinus comatus and Coprinellus truncorum were screened in liquid for their acetylcholinesterase inhibitory (AChE) activity. Both extracts were found to display inhibition of the aforementioned enzyme reaching similar IC₅₀ values of 0.62 ± 0.07 and 0.61 ± 0.03 mg/mL, respectively. According to the means of FTIR spectroscopy, these PSH extracts mostly contained β-glucans. However, the presence of some proteins and polyphenolics as minor ingredients were also detected. Compared with existing literature data for anti-AChE activity of the sugar samples, the findings within this study may be treated as a profound bioactivity. Consequently, this study puts some light on the possible use of the screened macrofungi in the palliative treatment of Alzheimer’s disease.     

天然气的组成与应用

由于我国天然气资源的大量发现以及原油可开采量的减少,利用天然气的技术和规模都获得快速发展,天然气的研究与开发越来越受到人们的关注。本文介绍了天然气的组成与最新的应用进展。     

Stereoselective synthesis of the cyclic ether core of (+)-laurenyne

A concise enantioselective synthesis of the cyclic ether core of the marine natural product (+)-laurenyne has been accomplished using ring-closing metathesis for medium-ring construction.     

火焰原子吸收光谱法测定天然气转化催化剂中的氧化钾

建立火焰原子吸收光谱法测定天然气转化催化剂中氧化钾的分析方法。该方法将催化剂样品和助溶剂四硼酸锂熔融后再用盐酸溶解定容,采用火焰原子吸收光谱仪对样品溶液进行测定。在优化的实验条件下,钾离子的质量浓度在0.05~0.50 mg/L范围内与吸光度呈良好线性关系,相关系数为0.9995。钾的方法检出限为0.001 mg/L,定量限为0.01 mg/L,测定结果的相对标准偏差为2.6%~4.3%(n=6),样品加标回收率为97.8%~102.3%。与HG/T 3543-2014中的酸溶制样法相比,该方法能够将催化剂样品中的难溶钾盐溶出,分析结果准确度更高,可用于天然气转化催化剂中氧化钾含量的测定。     

Fe原子活化乙烷的微观反应机理

本文采用密度泛函理论B3LYP方法在6-311 G(d,p)基组水平上研究了Fe原子催化乙烷反应的微观反应机理,优化了反应过程中各反应物、中间体、过渡态和产物的构型,并在同一水平上计算了反应中各驻点的振动频率,运用自然键轨道理论(NBO)方法分析了各物质的成键情况和轨道间相互作用。Fe原子对乙烷的活化过程可分为C-C键活化及C-H键活化,分别释放出CH4和H2。     

从奎宁到白三烯——-试论有机化学在医学科学中的重要作用

有机化学,特别是天然有机化学,是和医学科学密切相关的,有机化学的成就在许多方面促进了医学科学的进步,反过来医学科学中提出的课题也推动了有机化学的发展。本文以抗疟药等天然药物和廿碳酸类等生理活性物质为例讨论了这两门学科间的一些关系。     

Recent Results on Fast Flow Gas-Phase Partial Oxidation of Lower Alkanes

Recent experimental results and kinetic modeling of fast flow gas-phase oxidation of methane and other lower alkanes to methanol and other oxygenates are discussed,alongside with prospects and possible areas for applications of the processes.