Naturwirkstoffe aus Pflanzen. Biodiversitätsforschung

Due to its deepened natural material research the transdisciplinary biodiversity research offers new options to therapeutical challanges of the 21st century. Besides phytochemicals, known for centuries, these natural materials also include recently known material such as antiviral active high polymer polyphenols of Mediterranean rockroses or new kinds of antiadipos active bitter‐tasting compounds. Natural ressources are invaluable. To protect and preserve these, detailed knowledge of biodiversity on Earth and its embedding in the biogeosystem is required.     

Origins of life and biochemistry under high-pressure conditions

Life on Earth can be traced back to as far as 3.8 billion years (Ga) ago. The catastrophic meteoritic bombardment ended between 4.2 and 3.9 Ga ago. Therefore, if life emerged, and we know it did, it must have emerged from nothingness in less than 400 million years. The most recent scenarios of Earth accretion predict some very unstable physico-chemical conditions at the surface of Earth, which, in such a short time period, would impede the emergence of life from a proto-biotic soup. A possible alternative would be that life originated in the depth of the proto-ocean of the Hadean Earth, under high hydrostatic pressure. The large body of water would filter harmful radiation and buffer physico-chemical variations, and therefore would provide a more stable radiation-free environment for pre-biotic chemistry. After a short introduction to Earth history, the current tutorial review presents biological and physico-chemical arguments in support of high-pressure origin for life on Earth.     

Nickel‐Catalyzed Asymmetric Hydrogenation of 2‐Amidoacrylates

Earth‐abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2‐amidoacrylates, affording the chiral α‐amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α‐amino acids, β‐amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium‐labeling experiments and computational calculations.     

Surviving Mass Extinctions through Biomineralized DNA

Even in the worst of conditions, such as those which occurred during mass extinction events, life on Earth never totally stopped. Aggressive chemical and physical attacks able to sterilize or poison living organisms occurred repeatedly. Surprisingly, DNA was not degraded, denatured or modified to the point of losing the capability of transferring the genetic information to the next generations. After the events of mass extinction life was able to survive and thrive. DNA was passed on despite being an extremely fragile biomolecule. The potential implications of hydroxyapatite protection of DNA are discussed in this Concept article including how DNA acts as a template for hydroxyapatite (HAp) formation, how cell death can trigger biomineralization, and how DNA can be successfully released from HAp when the conditions are favorable for life.     

扫描电镜前级惰性气体保护装置的研制

本文介绍一种扫描电镜用前级惰性气体保护装置，它可用在氩气等惰性气体气氛不装卸易燃，易爆等活性极强的样品，从而实现了活性钙样品的扫描电镜观察与分析。     

Radiation-chemical processes leading to origination and accumulation of oxygen in the Earth’s atmosphere

The role of natural radioactivity in the formation of the oxygen atmosphere of the Earth is discussed. The origination of oxygen in the free state in the hydrosphere and atmosphere is associated with the radiolysis of the water of the World ocean under the irradiation of radio active isotopes ⁴⁰K, ²³⁵U, ²³⁸U, and ²³²Th. The calculations showed that within the last 3.8 billion years the total weight of oxygen, which could be formed due to this process, is about 7.4?10¹⁷ kg, i.е., the value of the same order as the oxygen content in the modern atmosphere of the Earth. The Ocean was an intermediate collector and provided the nucleation of new forms of biological life with oxygen respiration. The consecutive transformation of the Earth’s atmosphere with a gradual increase in the oxygen content became the result of photosynthesis in algae and green plants and thus opened a way to the origination of complicated forms of the life.     

On the application of electrochemical impedance spectroscopy to study the self-healing properties of protective coatings

Active corrosion protection based on self-healing of defects in coatings is a vital issue for development of new advanced corrosion protection systems. However, there is a significant lack of experimental protocols, which can be routinely used to reveal the self-healing ability and to study the active corrosion protection properties of organic and hybrid coatings.The present work demonstrates the possibility to use EIS (electrochemical impedance spectroscopy) for investigation of the self-healing properties of protective coatings applied on a metal surface. The model EIS experiments supported by SVET (scanning vibrating electrode technique) measurements show that an increase of low frequency impedance during immersion in the corrosive medium is related to the suppression of active corrosion processes and healing of the corroded areas. Thus, EIS can effectively be employed as a routine method to study the self-repair properties of different protective systems. The 2024 aluminium alloy coated with hybrid sol–gel film was used as a model system to study the healing of artificial defects by an organic inhibitor (8-hydroxyquinoline).     

A novel shielding material prepared from solid waste containing lead for gamma ray

Human beings are continuously exposed to cosmogenic radiation and its products in the atmosphere from naturally occurring radioactive materials (NORM) within Earth, their bodies, houses and foods. Especially, for the radiation protection environments where high ionizing radiation levels appear should be shielded. Generally, different materials are used for the radiation shielding in different areas and for different situations. In this study, a novel shielding material produced by a metallurgical solid waste containing lead was analyzed as shielding material for gamma radiation. The photon total mass attenuation coefficients (μ/ρ) were measured and calculated using WinXCom computer code for the novel shielding material, concrete and lead. Theoretical and experimental values of total mass attenuation coefficient of the each studied sample were compared. Consequently, a new shielding material prepared from the solid waste containing lead could be preferred for buildings as shielding materials against gamma radiation.     

Understanding prebiotic chemistry through the analysis of extraterrestrial amino acids and nucleobases in meteorites

The discoveries of amino acids of extraterrestrial origin in many meteorites over the last 50 years have revolutionized the Astrobiology field. A variety of non-terrestrial amino acids similar to those found in life on Earth have been detected in meteorites. A few amino acids have even been found with chiral excesses, suggesting that meteorites could have contributed to the origin of homochirality in life on Earth. In addition to amino acids, which have been productively studied for years, sugar-like molecules, activated phosphates, and nucleobases have also been determined to be indigenous to numerous meteorites. Because these molecules are essential for life as we know it, and meteorites have been delivering them to the Earth since accretion, it is plausible that the origin(s) of life on Earth were aided by extraterrestrially-synthesized molecules. Understanding the origins of life on Earth guides our search for life elsewhere, helping to answer the question of whether biology is unique to Earth. This tutorial review focuses on meteoritic amino acids and nucleobases, exploring modern analytical methods and possible formation mechanisms. We will also discuss the unique window that meteorites provide into the chemistry that preceded life on Earth, a chemical record we do not have access to on Earth due to geologic recycling of rocks and the pervasiveness of biology across the planet. Finally, we will address the future of meteorite research, including asteroid sample return missions.     

A study of a simulated low Earth environment on the degradation of FEP polymer

Spacecraft flying in a low Earth orbit environment require thermal blankets to provide protection from direct solar heat from the sun. Fluorinated ethylene propylene copolymer is one of the major components of these thermal blankets. In this study, the effect of a simulated low Earth orbit environment on FEP was investigated. UV and VUV degradation of fluorinated ethylene propylene (FEP) copolymer was studied using ESR and XPS. The ESR study revealed the formation of a terminal polymer chain radical. The stability of this radical has been investigated under different environments. An XPS study of FEP film exposed to VUV and atomic oxygen showed that oxidation takes place on the polymer surface. The study revealed also that the percentage of CF₂ in the polymer surface decreased with exposure time and the percentage of CF, CF₃ and carbon attached to oxygen increased. SEM micrographs of FEP film exposed to VUV and atomic oxygen produced a rough surface with regular undulations similar to sand dunes. © 1998 John Wiley & Sons, Ltd.     

Synthesis of Pt/C Electrocatalysts Under Protection of Glucose and Their Improved Methanol Electrooxidation Activity

Carbon supported Pt(Pt/C) electrocatalysts were prepared with glucose as protection agent and NaBH₄ as reductant. The Pt nanoparticles deposited on carbon support presented reduced size and well dispersity attributed to the protection effect of glucose. Glucose absorbed on the particle surface was readily removed by water washing without leading to agglomeration of the Pt nanoparticles. The as-prepared Pt/C electrocatalysts showed improved mass activity for methanol electrooxidation compared to the catalyst prepared without glucose protection. The improved performance is attributed to the larger electrochemical active surface area thus increased active sites on the Pt/C elctrocatalysts prepared under the protection of glucose.     

Gas chromatography active ingredient control of aerosol insecticide from Algerian market

Household insecticide products are common and a popular mode of personal protection against household insect pests in all parts of the world. A chromatographic method for the control of aerosol insecticide active ingredient content was developed to be simple and rapid for the inspection of the numerous products for professional and private uses proposed in the Algerian market. Throughout, the most sold aerosol insecticides only two over eight were fair to the label declaration. However, the product labels need the addition of some details, like the active ingredients concentrations.     

Thermal analysis scheme aimed at better understanding of the Earth’s climate changes due to the alternating irradiation

Methodological scheme of thermal analysis is used for portraying the Earth environmental research and climate changes showing particularly the history, effect of atmosphere reflection (albedo) and absorption (so called greenhouse effect included). The net behavior of the Earth as a black body is reviewed. The most influential on climate changes is alteration of the geometry of the Earth trajectory and the irradiative power of the Sun (as a standard thermo-analytical pair of the sample and radiator). Thermodynamic basis of water vapor impacts is pointed out, the absorption spectra of atmosphere emphasized and temperature gradients indicated. The historical course of the Earth temperature and CO₂ concentration is put in analogy with the method of gas desorption analysis, which supports the view that the variation of CO₂ concentration recorded in the past may not be alone blamed for temperature changes.     

Solar UV irradiation conditions on the surface of Mars

The UV radiation environment on planetary surfaces and within atmospheres is of importance in a wide range of scientific disciplines. Solar UV radiation is a driving force of chemical and organic evolution and serves also as a constraint in biological evolution. In this work we modeled the transmission of present and early solar UV radiation from 200 to 400 nm through the present-day and early (3.5 Gyr ago) Martian atmosphere for a variety of possible cases, including dust loading, observed and modeled O3 concentrations. The UV stress on microorganisms and/or molecules essential for life was estimated by using DNA damaging effects (specifically bacteriophage T7 killing and uracil dimerization) for various irradiation conditions on the present and ancient Martian surface. Our study suggests that the UV irradiance on the early Martian surface 3.5 Gyr ago may have been comparable with that of present-day Earth, and though the current Martian UV environment is still quite severe from a biological viewpoint, we show that substantial protection can still be afforded under dust and ice.     

不平“钒”的金属元素*

钒是地壳中含量第21丰富元素,是人体必需的微量元素。介绍钒元素的发现、自然分布以及在人体内的循环。重点从化学结构分析钒酸盐磷酸盐的拮抗作用机制,从生化机理阐述钒化合物对激酶与磷酸酶的调节、对RNA和DNA功能的影响、对活性氧作用的影响,从人体健康视角探讨钒对治疗糖尿病和癌症及保护心血管等的潜在药理学作用。     

糖合成中羟基的保护和去保护方法

糖中含有多个活泼的羟基.羟基的保护和去保护在有关糖的合成中具有很重要的意义.最常用的羟基保护基可归纳为三类:酯类、醚类和缩醛或缩酮类.作者对每一类中具体的羟基保护基的性质、应用作了简单综述,重点介绍了保护基的引入和脱去的方法.     

Thermodynamic indicators for environmental certification

The Earth is an open thermodynamic system, that remains in a steady state far from the equilibrium, through energy and matter exchanges with the surrounding environment. These natural constraints, which prevent the system from maximizing its entropy, are threatened by human action and our ecosystem needs urgent protection. In this viewpoint the environmental certification was born, according to international standards ISO 14001, ISO 14040, and European Regulation EMAS. These are voluntary adhesions to a program of environmental protection by companies, administrations and organizations which, starting from the respect of the existing environmental laws and regulations, decide to further improve their environmental performance. To obtain and maintain certification of a system is necessary to apply some indicators to evaluate its environmental performance and to demonstrate its progressive improvement. Here we propose to use for this purpose the thermodynamic indicators produced from energy analysis by Odum. The case study is Montalcino city (Italy) and energy indicators are used to evaluate environmental performance of this system where exist different activities, from agricultural productions, to tourism. Results show that energy analysis could become a valid standard monitoring method for environmental certification, especially in consideration of its wide application field.     

Radiation chemistry approach to the study of sedimentary microenvironments as models for the protection of bio-organic molecules on the early earth

This work examines the influence of sodium montmorillonite on the chemical transformations undergone by two nucleosides (cytidine and adenosine) in simulated primitive Earth conditions. The aim of this study is to test the hypothesis of a protective role of solid surfaces like clay for organic compounds adsorbed on them, when exposed to external sources of ionizing radiation (γ-ray). The results showed this role of protection: the decomposition of nucleosides was lower when adsorbed on a clay mineral. It was also found that a purinic nucleoside (more than pirimidinic) was quickly adsorbed on clay at low pH and desorbed in neutral or lightly basic aqueous solutions. For analysis of samples, different techniques were used: X-ray diffraction, UV–Vis spectroscopy, and HPLC.     

Enzymatic mechanisms of biological magnetic sensitivity: nuclear spin effects

Intracellular enzymatic reactions involving ion-radical states are shown to act as a universal mechanism of magnetically sensitive living organisms. Weak magnetic fields can affect the rate of intracellular enzymatic reactions. The main magnetically sensitive stage is the singlet-triplet conversion of ion-radical pairs in the active sites of enzymes induced by Zeeman and hyperfine interactions of electron and nuclear spins. The participation of a nuclear spin in the ion-radical process results in a strong dependence of the enzymatic reaction rate in weak magnetic fields comparable with the magnetic field of the Earth.     

Sensitivity of erythemally effective UV irradiance and daily exposure to uncertainties in measured total ozone

In this study the sensitivity of the erythemally effective radiation to uncertainties in operationally measured total ozone content of the atmosphere (TOC) was estimated. For this, daily operational TOC measurements from different instruments were applied covering the period from 1997 to 1999. Measurements were gained from space by Earth Probe Satellite, Earth Remote Sensing satellite/Global Ozone Monitoring Experiment and Operational Vertical Sounder and from the ground by Dobson and Brewer spectrophotometers for the locations of Hradec Kralove (Czech Republic, 50 degrees N), Nairobi (Kenya, 1 degrees S) and Springbok (Republic of South Africa, 30 degrees S). The values were used as input parameter to model calculations of erythemally effective irradiance and daily radiant exposure. The differences due to the use of TOC from different sources were analyzed with respect to the Ultraviolet Index (UVI). The UVI was introduced as a tool for sun protection and health care. Therefore, it is of special importance to know the restriction of accuracy. As a tool of health care, the maximum uncertainties are of interest and are described in using the 95%-percentile and the maximum differences. This study shows that differences, i.e. uncertainties (95%-percentile) are in the order of 1 UVI. Independently on the location, however, extreme differences may overstep 3 UVI. For the daily dose the 95%-percentile is around 7.5 UVI hours (UVIh) but differences higher than 20 UVIh were also found.