Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

Detection of Synthetic Antioxidants: What Factors Affect the Efficiency in the Chromatographic Analysis and in the Electrochemical Analysis?

Antioxidants are food additives largely employed to inhibit oxidative reactions in foodstuffs rich in oils and fat lipids, extending the shelf life of foodstuffs and inhibiting alterations in color, flavor, smell, and loss of nutritional value. However, various research has demonstrated that the inadequate use of synthetic antioxidants results in environmental and health problems due to the fact that some of these compounds present toxicity, and their presence in the human body, in high concentrations, is related to the development of some cancer types and other diseases. Therefore, the development of analytical methods for identifying and quantifying synthetic antioxidants in foodstuffs is fundamental to quality control and in ensuring consumer food safety. This review describes the recent chromatographic and electrochemical techniques used in the detection of synthetic phenolic antioxidants in foodstuffs, highlighting the main characteristics, advantages and disadvantages of these methods, and specific typical features, which include extraction methods for sample preparation and materials used in the working electrode construction, considering chromatographic and voltammetric methods, since these specific features influence the efficiency in the analysis.     

青藏高原湖泊影响锂元素迁移和富集的矿物、元素及环境因素——以西藏郭扎错钻孔沉积物为例

作为我国战略性矿产的锂矿,主要赋存于青藏高原盐湖中。湖泊系统中,锂的富集和迁移规律关系到锂矿的高效提取和未来锂矿的储量估算。本文以西藏咸水湖郭扎错的钻孔沉积物为例,结合AMS14C年代和Mg元素含量变化,系统分析了孔隙水、碳酸盐矿物和硅酸盐矿物的锂含量变化,探讨了矿物、镁元素、环境变化和早期成岩作用等对锂元素迁移和富集的影响。郭扎错沉积物中锂和镁大部分存在于硅酸盐矿物中,锂和镁较高的相关性说明二者存在于相同的硅酸盐矿物中,如粘土矿物。大约90%的锂赋存在硅酸盐矿物中,约8.5%的锂赋存在碳酸盐矿物中,孔隙水中的锂含量占比仅约1.5%。碳酸盐矿物中Mg/Li摩尔比值为78–270,是孔隙水中10多倍,而硅酸盐矿物中的Mg/Li摩尔比值稳定在24–29之间。水–沉积物相互作用促进硅酸盐矿物中锂的释放,咸水环境下释放的锂多于淡水环境下。碳酸盐矿物中,锂和镁主要存在于方解石中。镁离子对锂离子的迁移具有阻碍作用,低温、高盐度下的阻碍作用更强。湖泊沉积物可能是湖水锂的一个重要来源。     

Pesticide residues in groundwaters and soils of agricultural areas in the Águeda River Basin from Spain and Portugal

This research has evaluated the agricultural impact of the use of pesticides in small agricultural areas in the Águeda river basin, which straddles the Spanish-Portuguese border. Sixteen pesticides frequently used in the area, including herbicides, fungicides and insecticides and some of their degradation products, were monitored in 52 groundwater samples and 42 soil samples taken around them, using a developed multi-residual analytical method based on SPE-LC-MS. Sampling was carried out in two different seasons (winter and summer). The results indicated the presence of pesticides at several levels, both in groundwaters and soils. Thirteen of the pesticides studied were detected in one or more of the groundwater samples analysed, but only three pesticides were detected in the soil samples. Terbuthylazine, cyprodinil, tebuconazole and chlorpyrifos were the pesticides most frequently detected in groundwaters, whereas terbuthylazine, metalaxyl and tebuconazole were the sole compounds detected in soils. The distribution of the concentrations in groundwaters indicated that up to 80% and 70% of the samples collected in the summer on the Spanish and Portuguese sides, respectively, exceed the quality standards of 0.1 µg L^?1 for one or more individual compounds and, in turn, up to 64% and 40% exceed the quality standards of 0.5 µg L^?1 for all compounds. The presence of pesticide residues in the groundwaters and soils analysed may well be explained by the use of these compounds in agricultural practices.     

The Therapeutic Potential of Celastrol in Central Nervous System Disorders: Highlights from In Vitro and In Vivo Approaches

Celastrol, the most abundant compound derived from the root of Tripterygium wilfordii, largely used in traditional Chinese medicine, has shown preclinical and clinical efficacy for a broad range of disorders, acting via numerous mechanisms, including the induction of the expression of several neuroprotective factors, the inhibition of cellular apoptosis, and the decrease of reactive oxygen species (ROS). Given the crucial implication of these pathways in the pathogenesis of Central Nervous System disorders, both in vitro and in vivo studies have focused their attention on the possible use of this compound in these diseases. However, although most of the available studies have reported significant neuroprotective effects of celastrol in cellular and animal models of these pathological conditions, some of these data could not be replicated. This review aims to discuss current in vitro and in vivo lines of evidence on the therapeutic potential of celastrol in neurodegenerative diseases, including Alzheimer’s and Parkinson’s diseases, amyotrophic lateral sclerosis, Huntington’s disease, multiple sclerosis, and cadmium-induced neurodegeneration, as well as in psychiatric disorders, such as psychosis and depression. In vitro and in vivo studies focused on celastrol effects in cerebral ischemia, ischemic stroke, traumatic brain injury, and epilepsy are also described.     

壳聚糖及其在分析化学中的应用

综述了壳聚糖、甲壳素在污水处理、电化学、原子吸收光谱、高效液相色谱、吸光光度法中的应用。引用文献28篇。     

煤烘玉米和饮水为介质地氟病区骨畸形病人全血尿多元素含量的分析

采集了贵族个煤烘玉米为主要介质和河北２个饮水为介质氟病区内骨畸形病人的全血、尿、检测了其中８种元素含量,结果表明,贵州各氟病区少儿骨软化与成年骨硬化畸形病人的全血铝、钙、磷、铁和尿氟、铝均显著高于同龄对照组,尿磷均低于同龄对照组。少儿骨软化病人全血锌均下降,尿锌多下降。某水型氟病区骨软化经产妇尿氟、全血铜升高;骨软化少年全血铝显著升高,锌、铁下降,尿氟升高,尿锌,磷下降。海边的典型氟骨症病人全血、     

煎煮对几种特色南药中重金属元素含量和形态影响

考察了几种特色南药中重金属(Cd,Cr,Cu,Fe,Mn,Ni,Pb,Sr,Zn)的含量状况,并采用形态连续萃取法分析重金属在药材中的形态分布,研究了药材煎煮时药材中重金属的释放及煎煮过程对药材中重金属形态分布的影响。结果表明,几种南药中Cr,Pb,Zn的含量较高,且巴戟天中的重金属总量高于限量标准;原药材中Cr,Cu,Mn,Ni,Pb和Zn主要存在于有机态和残留态,Fe和Sr主要存在于残留态。煎煮使南药中大量重金属迁移到药汤中;药汤中Cu,Mn,Cr,Pb和Zn主要来自于其在药材中的可交换态、碳酸盐结合态和有机态,而药汤中Sr,Ni和Fe不仅包含其非残留态,更多来自于它们的残留态。为减少药汤中重金属,对于Cu,Mn,Cr,Pb和Zn既要控制在药材中的总量,且需降低它们在药材中的非残留态含量;对于Fe,Ni和Sr则主要是控制其在药材中的总量。     

Physiological changes in barley plants under combined toxicity of aluminum, copper and cadmium

Crop production on acid soil is markedly reduced, further, a multiple heavy metal pollution except Al on acid soil is detected in many areas. The present study was undertaken to assess the toxicities of Al, Cd, and Cu separately and in combinations, three heavy metals very often coexisting on acid soil, and to identify their interactions in two kinds of barley seedlings differing in Al tolerance. The plant growth, metals accumulations, total soluble protein and sugar contents, MDA contents and the activities of SOD and POD were estimated in roots and leaves after 5-week supply of the heavy metals excess in the nutrient solution. The results indicated that the stress treatments including low pH (pH 4.5) alone all adversely affected plant growth and disturbed the cell metabolism seriously. The development of toxic symptoms corresponded to a high accumulation of Al, Cd, Cu and to a poor increase in soluble sugar contents but to a high increase in MDA contents, to the decrease in soluble protein contents and to the much elevated SOD and POD activities in both roots and leaves. In addition, binary metal combinations of Al + Cd and Al + Cu both produced the synergistic response for the growth of barley seedlings, in particular for Shang 70-119, while, ternary metal combination of Al + Cu + Cd produced different interactions in two kinds of genotypes, thus, the significant synergistic response was seen in Shang 70-119, but the antagonistic response was detected in Gebeina. The different responses to ternary metal combination of two genotypes may result from the different metal bioaccumulation patterns, hence, the existence of Cd and Cu promoted Al accumulation in Shang 70-119 but inhibited Al accumulation in Gebeina.     

GC-MS analysis of penta- and tetra-cyclic triterpenes from resins of Pistacia species. Part II. Pistacia terebinthus var. Chia

Pistacia species contain oleoresins with bioactive triterpenes. In this study triterpenes, including minor components, were identified and quantified in both neutral and acidic fractions of Pistacia terebinthus var. Chia resin, grown exclusively in Chios island (Greece), collected traditionally, as well as using stimulating agents (liquid collection). It was proved that these two resin samples were composed of several different minor triterpenes, while major constituents were similar but in different proportions. Compounds that differentiated two resin samples of P. lentiscus and P. terebinthus var. Chia, both traditionally collected, were detected, in order to identify the nature of resins present in archaeological materials. In the traditionally collected resin, 37 triterpenes were identified, 12 in the acidic and 25 in the neutral fraction. In the liquid collection resin 10 compounds were identified in the acidic and 23 in the neutral fraction, while 16 compounds were not contained in the traditionally collected resin. The main triterpenes in both resin samples collected traditionally and using stimulating agents were: isomasticadienonic acid (23.6 and 26.3% w[sol ]w of the triterpenic fraction, respectively), 28-norolean-17-en-3-one (16.3 and 17.5% w[sol ]w of the triterpenic fraction, respectively) and masticadienonic acid (5.8 and 6.0% w[sol ]w of the triterpenic fraction). In this study the qualitative and quantitative composition of triterpenes was compared in the Pistacia lentiscus and P. terebinthus var. Chia resin samples collected with the traditional and new liquid techniques, and also triterpenes in resins of P. terebinthus obtained by the traditional technique and using stimulating agents. The aim of the study was also to examine whether the collection technique influenced the triterpenes contained in P. terebinthus var. Chia resin samples.     

Effects of dilute acid and steam explosion pretreatments on the cellulose structure and kinetics of cellulosic fraction hydrolysis by dilute acids in lignocellulosic materials

Worldwide, yellows diseases impact plants important in human nutrition, the natural environment, and the culture and commerce of humans. Since the presumed pathogens, mycoplasma-like organisms (MLOs), have not been isolated in pure culture in vitro, their study must proceed by other experimental approaches. In a study of disease affecting grapevines in Europe and North America, polymerase chain reactions (PCR) and restriction analyses of PCR-amplified DNA were used to detect and differentiate strains of MLOs associated with grapevine yellows. MLOs were detected both in naturally diseased grapevines and in experimentally inoculated host plants. The data indicated an unexpected genomic diversity among grapevine-infecting MLOs, and supported their classification with MLOs in the aster yellows, X-disease, and elm yellows groups. The presence of diverse MLOs in grapevines provokes consideration that these MLOs may be present in overlapping geographic ranges and that multiple MLO infections may occur in individual plants, increasing the complexity of grapevine yellows epidemiology and control and the significance of sensitive MLO detection in planting stock and phytosanitary-regulated germplasm.     

石柱黄连及根际土壤中矿质元素特征分析

研究石柱黄连不同器官及其根际土壤中矿质元素特征,探究黄连根茎矿质元素间及其与土壤环境的相关性。采用电感耦合等离子体质谱法(ICP-MS)、电感耦合等离子体发射光谱法(ICP-OES)及原子荧光光谱法(AFS)测定了15组石柱黄连植株和根际土壤中18种矿质元素含量,所得数据运用SPSS 22.0统计软件分析。石柱黄连根际土壤中锰、磷、镁、镉、汞等元素含量的变异性较大,部分采样点土壤中镉含量超过农用地土壤污染风险筛选值。在检测的18种元素中,黄连植株中钙、镁、磷、钾含量最高,其次是铁、锰、锌,再次是锶、铜、镍,最后是铅、钒、钴、镉、钼、铬、砷、汞。须根对大部分矿质元素的富集能力强于根茎或地上部;黄连根茎对锌的富集能力强于须根或地上部;地上部对钙、磷、钾、铬的富集能力强于须根或根茎。Spearman分析表明黄连根茎矿质元素间、黄连根茎与土壤中矿质元素有一定相关性,部分具有统计学意义(P＜0.05)。石柱黄连不同器官中矿质元素含量有明显差异,以此建立的指纹图谱可用于区分黄连根茎及须根的粉末样品;黄连根茎中矿质元素间主要表现为协同作用,黄连根茎与土壤中矿质元素既有协同作用又有拮抗作用。     

Zinc in gastrointestinal and liver disease

Zinc is an essential trace element with important biological functions, depending on the structural and/or catalytic role played by zinc ions in a large variety of enzymes. Zinc plays a critical role in cellular integrity, protein synthesis, nucleic acid metabolism, contributing to cell growth, proliferation, differentiation and death. The present review reports data on zinc homeostasis and metabolism, zinc absorption, intercellular trafficking, intracellular transport inside enterocytes and hepatocytes. Particular emphasis is given to data regarding the role of zinc carriers ZnTs and Zips, and to their expression in liver and gut in experimental and in human studies. The role of zinc in the gastrointestinal tract and in the liver as a powerful antioxidant and its relationship with apoptosis is discussed. Possible implications of zinc status in different disorders of the gastrointestinal tract are presented, focusing on its possible introduction in the therapy of inflammatory bowel diseases. Data on the role of zinc and zinc carriers in the evolution of liver fibrosis towards cirrhosis are also discussed. Finally, data on the ability of zinc therapy to obtain regression of liver cirrhosis in patients affected by Wilson's disease are reported, and the hypothesis that zinc could protect against liver fibrosis in chronic liver disease of different origin is presented.     

Anticancer and Antibiotic Rhenium Tri- and Dicarbonyl Complexes: Current Research and Future Perspectives

Organometallic compounds are increasingly recognized as promising anticancer and antibiotic drug candidates. Among the transition metal ions investigated for these purposes, rhenium occupies a special role. Its tri- and dicarbonyl complexes, in particular, attract continuous attention due to their relative ease of preparation, stability and unique photophysical and luminescent properties that allow the combination of diagnostic and therapeutic purposes, thereby permitting, e.g., molecules to be tracked within cells. In this review, we discuss the anticancer and antibiotic properties of rhenium tri- and dicarbonyl complexes described in the last seven years, mainly in terms of their structural variations and in vitro efficacy. Given the abundant literature available, the focus is initially directed on tricarbonyl complexes of rhenium. Dicarbonyl species of the metal ion, which are slowly gaining momentum, are discussed in the second part in terms of future perspective for the possible developments in the field.     

中性溶质在反相毛细管电色谱中的保留行为

分别在以甲醇、乙腈、异丙醇和四氢呋喃为有机改性剂的４种二元流动相体系中对中性溶质在反相毛细管电色谱中的保留行为进行了研究。不仅考察了有机改性剂的种类和浓度对电渗淌度的影响,而且建立了溶质容量因子与有机改性剂在流动相中体积分数间的定量关系,此外还对样品在反相毛细管电色谱和反相毛细管高效液相色谱中的保留行为进行了比较,发现中性溶质在这两种分离模式中的容量因子基本相同。     

表面活性剂与叶酸的相互作用及其对光氧化降解的影响

表面活性剂与有机小分子作用不仅能提高表面活性剂的聚集能力,还能提高小分子的溶解度、稳定性等应用性能,因此研究二者之间的相互作用机理对于促进表面活性剂的发展和实际应用具有重要意义。本工作提出了一种利用功能有机小分子调控表面活性剂聚集行为,进而提高不稳定小分子自身稳定性的新策略。利用表面张力、紫外可见吸收光谱、荧光光谱、动态光散射、等温滴定量热和核磁共振技术研究了在p H为7.0时,叶酸分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)、季铵盐Gemini 12-6-12和季铵盐线性三聚12-3-12-3-12四种表面活性剂之间的相互作用及其导致的叶酸光氧化降解性能的变化,结果表明,阴离子表面活性剂SDS抑制叶酸光氧化降解的效率较低,而阳离子表面活性剂都能够显著抑制叶酸的光氧化降解,且随着表面活性剂寡聚度的增加,抑制效果增强,所需表面活性剂的浓度显著降低,寡聚表面活性剂12-3-12-3-12的抑制效率高达96%。     

谈科学探究中的归纳与演绎

逻辑推理过程与事物的认识过程同时存在,科学探究离不开逻辑推理过程。归纳和演绎是认识过程中的两种逻辑推理形式,在学生的科学探究活动中,尤其是在提出问题、猜想与假设、设计实验方案与解释结论阶段,归纳和演绎发挥着重要的作用。本文重点论述了寻求现象原因的求异归纳推理、探寻化学物质通性及变化规律的不完全归纳推理、探求个别物质性质的演绎三段论、解释个别现象的演绎解释推理过程在科学探究中的重要作用。     

伊敏褐煤中微量元素的地球化学特征及其无机-有机亲和性分析

采用脱矿物质、提取腐殖酸等方法结合ICP-MS对伊敏15_上、16_下煤中的32种微量元素的含量及其赋存特征进行了分析。与地壳克拉克值及中国侏罗-白垩纪煤和世界褐煤中微量元素含量相比,伊敏褐煤中微量元素没有明显富集。脱矿物质处理后,Ni明显富集,As略比原煤高,其他微量元素都低于原煤。原煤提取腐殖酸和脱矿物煤提取腐殖酸中Ni、Mo、Cd、Sn、W明显富集,这表明Ni、Mo、Cd、Sn、W和腐殖酸形成了稳定的有机态化合物。原煤提取腐殖酸残煤和脱矿物煤提取腐殖酸残煤中V、Ni、As富集,表明V、Ni、As与煤的大分子结构形成了稳定的有机态化合物。根据微量元素和灰分的相关性系数,把微量元素分为以下几类:无机富集元素Cr、U;亲无机元素Cu、Cd、In、Sn、Ga、Y、Zr、Hf、Bi、Th;偏无机元素Be、Sc、Rb、Sr、Nb、Cs、Ta、Pb;偏有机元素V、As、Tl、Ba、Se;亲有机元素Li、Co、W;有机富集元素Ni、Zn、Mo、Sb。     

Antioxidative effects of flavonols and their glycosides against the free-radical-induced peroxidation of linoleic acid in solution and in micelles

The antioxidative effect of flavonols and their glycosides against the peroxidation of linoleic acid has been studied in homogeneous solution (tBuOH/H(2)O, 3:2) and in sodium dodecyl sulfate and cetyl trimethylammonium bromide micelles. The peroxidation was initiated thermally by the water-soluble initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides. The synergistic antioxidant effect of the flavonols with alpha-tocopherol (vitamin E) was also studied by following the decay kinetics of alpha-tocopherol and the alpha-tocopheroxyl radical. Kinetic analysis of the antioxidative process demonstrates that the flavonols are effective antioxidants in solution and in micelles, either alone or in combination with alpha-tocopherol. The antioxidative action involves trapping the initiating radicals in solution or in the bulk-water phase of the micelles, trapping the propagating lipid peroxyl radicals on the surface of the micelles, and regenerating alpha-tocopherol by reducing the alpha-tocopheroxyl radical. It was found that the antioxidant activity of the flavonols and their glycosides depends significantly on the position and number of the hydroxy groups, the oxidation potential of the molecule, and the reaction medium. The flavonols bearing ortho-dihydroxy groups possess significantly higher antioxidative activity than those without such functionalities, and the glycosides are less active than their parent aglycones. The activity of the flavonols is higher in micelles than in solution, while the activity of alpha-tocopherol is lower in micelles than in solution. This is because the predominant factor for controlling the activity is the hydrogen-bonding interaction of the antioxidant with the micellar surface in the case of hydrophilic flavonols, while it is the inter- and intramicellar diffusion in the case of lipophilic alpha-tocopherol.