温和条件下氧分子的活化和活性氧种的反应

固氧问题和氮、二氧化碳的固定同样都是人类认识自然、利用自然的重要课题。近年来,人们开始对氧在温和条件下的活化和反应问题发生极大兴趣,这是和下面二个待开发的领域受到普遍注意分不开的。     

Determination of Heavy Metals as Environmental Pollutants: Use of Instrumental Neutron Activation Analysis

The simultaneous determination of heavy metals by instrumental neutron activation analysis (INAA) in some environmental samples have been considered. A new approach has been proposed to assess the potentialities and the most adequate use of INAA for each particular heavy metal.     

环境样品中痕量锑的形态分析研究进展

总结了近年来环境样品中痕量锑的测定方法研究进展,内容包括水环境体系中锑的赋存形态、传统的样品预处理和分离富集技术、现代仪器在线分离分析技术,并指出了痕量元素锑形态分析存在的问题和未来的发展方向。     

环境样品中痕量锑的形态分析研究进展

环境样品中不同形态锑,其生物活性及其毒性不同,其形态分析具有重要意义。由于环境样品中锑的含量相对较低,不同形态锑的分析具有挑战性。归纳总结了环境样品中痕量超痕量锑的形态分析概况及近年来的发展趋势,内容主要包括样品的前处理和不同形态锑的分析方法,指出了未来的发展方向。     

Determination of Chemical Species of Arsenic in Environmental Waters for Endemic Arsenism Disease Area of Inner -Mongolia by Neutron Activation Analysis

The areas of endemic arsenic disease in the Akabaming of Inner-Mongolia belong to the drinking-water type arsenism disease area. Patients who are living the high arsenic area are more than three hundred thousand.     

Chemical Diversity and Biological Activity of Secondary Metabolites Isolated from Indonesian Marine Invertebrates

Marine invertebrates have been reported to be an excellent resource of many novel bioactive compounds. Studies reported that Indonesia has remarkable yet underexplored marine natural products, with a high chemical diversity and a broad spectrum of biological activities. This review discusses recent updates on the exploration of marine natural products from Indonesian marine invertebrates (i.e., sponges, tunicates, and soft corals) throughout 2007–2020. This paper summarizes the structural diversity and biological function of the bioactive compounds isolated from Indonesian marine invertebrates as antimicrobial, antifungal, anticancer, and antiviral, while also presenting the opportunity for further investigation of novel compounds derived from Indonesian marine invertebrates.     

New Developments in Activation Analysis for Material and Environmental Sciences

Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high-purity materials where concentrations of ppb's and sub ppb's have to be measured. NAA is specially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15 cm diameter can be irradiated with 4 × 10¹³n. cm^?2. sec^?1 and the irradiation is done for 72–96 hours. using large Ge(Li) detectors (100 to 150cc) and long counting time (8–16 hours) they measured 22 elements in concentrations below ppb and 10 others between ppb and 300 ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separtion. Several other semiconductor material such as Sc, Te, GaP and CuInS₂ were also determined by NAA. Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or ³He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis. The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their posible toxicological hazards, their source identification and for studies of atmospheric transport processes.     

Species Diversity and Secondary Metabolites of Sarcophyton-Associated Marine Fungi

Soft corals are widely distributed across the globe, especially in the Indo-Pacific region, with Sarcophyton being one of the most abundant genera. To date, there have been 50 species of identified Sarcophyton. These soft corals host a diverse range of marine fungi, which produce chemically diverse, bioactive secondary metabolites as part of their symbiotic nature with the soft coral hosts. The most prolific groups of compounds are terpenoids and indole alkaloids. Annually, there are more bio-active compounds being isolated and characterised. Thus, the importance of the metabolite compilation is very much important for future reference. This paper compiles the diversity of Sarcophyton species and metabolites produced by their associated marine fungi, as well as the bioactivity of these identified compounds. A total of 88 metabolites of structural diversity are highlighted, indicating the huge potential these symbiotic relationships hold for future research.     

Determination of Traces of Uranium and Thorium in Environmental Matrices by Neutron Activation Analysis

Radioactive elements like ²³²Th and ²³⁸U along with their daughter products, form part of all environmental matrices and are getting transferred to living beings by different pathways, leading to a continuous radiation exposure and need to be monitored. This paper presents an analytical methodology, highlighting the need to separate interfering beta- and gamma-emitters from the analytes, when neutron activation analysis is employed for the determination of traces of uranium and thorium in soil and plant materials. The method has been applied to the soil and plant materials from selected regions of India, along with standard reference materials to verify the validity of the proposed separation scheme. The overall reproducibility of the procedure was 2–10%. The concentration values of uranium and thorium so obtained, have been used to calculate transfer factors from soil to various parts of wheat plant.     

Determination of Selenium Species in Environmental Samples

 The essential nature of selenium as well as its toxicity depend on the concentration and the chemical forms in which this element is present in a given sample. Dissolved inorganic selenium can be found in natural water and soil as selenides, selenite and selenate. Organoselenium compounds present in air, soil and plants are volatile methylselenides, trimethylselenonium ion and several selenoamino acids. This review is a summary of recent research on the determination of selenium species in environmental samples such as water, air, soil and plants. Stability of selenium species in solutions and their storage is also discussed. In the metabolic pathway in the body selenide could act as the common intermediate for inorganic and organic Se sources as well as the checkpoint between further utilisation and excretion of selenium. Received May 30, 2001; accepted October 19, 2001; published online July 15, 2002     

Determination of Arsenic and Mercury in Various Environmental Matrices by Chemical Neutron Activation Analysis

Chemical neutron activation analysis was developed for determining trace amounts of arsenic and mercury in a variety of environmental matrices, including water, sediment, rock, plants, animal organs, etc: The adsorption procedure via magnesium oxide as the agent was applied to preconcentrate arsenic from the digested environmental matrices where arsenic in the form of As(V) ion could be highly efficiently adsorbed by hydrous magnesium oxide. On the other hand, the extraction procedure via lead diethyldithiocarbamate as the agent was applied to preconcentrate mercury from the digested environmental matrices where mercury in the form of Hg(II) ion could be highly efficiently extracted into the solution of lead diethyldithiocarbamte in dichloromethane. Both of the preconcentrated materials prepared ultimately in the solid states, i.e., arsenic in magnesium oxide and mercury in lead diethyldithiocarbamte were taken to be neutron irradiated. The γ spectra of the preconcentrated samples irradiated generally showed clear peaks of the product radionuclides from arsenic or from mercury by the different separation procedures. The possible interfering elements such as Na, Br, etc., were prominently minimized in respect of most of the preconcentrated samples. The reliability and accuracy of the proposed analytical methods for detecting arsenic and mercury can be confirmed by the assay of commercial standard reference materials including sediment, rock, plants, and animal organs.     

Activation of Dihydrogen by Masked Doubly Bonded Aluminum Species

Activation of dihydrogen by masked dialumenes (Al=Al doubly bonded species) is reported. Reactions of barrelene‐type dialumanes, which have the reactivity as masked equivalents of 1,2‐diaryldialumenes ArAl=AlAr, with H₂ afforded dihydroalumanes ArAlH₂ at room temperature (Ar: bulky aryl groups). These dihydroalumanes form hydrogen‐bridged dimers [ArHAl(μ‐H)]₂ in the crystalline state, while a monomer–dimer equilibrium was suggested in solution. The 1,2‐diaryldialumenes generated from the barrelene‐type dialumanes are the putative active species in the cleavage of H₂.     

一种新的测定铱丰度及其化学形态的放射化学中子活化分析法

本工作建立了一个以长链伯胺N_(1923)萃取为基础的放射化学中子活化分析法,可测定含量低达10~(-12)g/g的Ir。影响Ir萃取率的关键是Ir在水溶液中的化学形态,而不是其价态。此外,我们发展了一个用于地质样品物相分离的化学分相方法,研究了白垩系-第三系界线粘土样品中异常Ir的赋存状态。     

有关“环境友好塑料”几个概念的澄清

生物塑料、生物降解塑料、生物基塑料统称为环境友好塑料,但它们三者的侧重点各有不同,既有区别,也有联系,本文对以上三个概念的意义做了详细的解释和澄清。生物塑料注重于生产原料的生物来源性和制造过程的生物技术性;生物降解塑料则注重于它是否可以被生物降解,其原料可以来自于可再生资源,也可来自于石油资源;生物基塑料则关注其生产原料是否来自于可再生资源,而对其是否可以生物降解没有特别要求。     

Instrumental Neutron Activation Analysis of Iodine Levels in Fourteen Seaweed Species from the Coastal Belt of Ghana

Fourteen seaweed species were sampled from October 1997 to May 1999 along the rocky shores of Ghana, which is being washed by the Gulf of Guinea (part of the Atlantic Ocean). Instrumental neutron activation analysis (INAA) was used to measure the iodine levels in the species, with the basic aim of selecting seaweed species that are rich in iodine and hence can be used as supplement in the diet of humans. This is to help solve the problems associated with iodine deficiency disorders (IDD). The levels of iodine found in the seaweed species ranged between 55 to 804 ppm. The precision, expressed in terms of relative standard deviation, and accuracy of measurements are within ±5–10%. The results show high variability in and between species and among sampling sites. The high values of iodine concentrations in the macroalgae suggest that these marine organisms can be used as supplement in the diet of humans.     

Alkali Metal Species in the Reversible Activation of H2

MP(tBu)₂ (M=Li, Na, K), KH and KN(SiMe₃)₂ are shown to activate HD reversibly. In the case of MP(tBu)₂ this leads to isotopic scrambling and the formation of H₂, D₂, H(D)P(tBu)₂ and MH(D) in C₆D₆. In toluene, KP(tBu)₂ reacts with H₂ but also leads to isotopic scrambling into the methyl groups of the solvent toluene. DFT calculations reveal that these systems effect H₂ activation via cooperative interactions with the Lewis acidic alkali metal and the basic phosphorus, carbanion, or hydride centres, mimicking frustrated Lewis pair (FLP) behaviour.