Natürliche Bildung von halogenierten Essigsäuren und Iodalkanen

ABSTRACT This thesis deals with organohalogen compounds and their formation by natural abiotic soil processes, providing a framework in which a literature survey and a resume of the multitude of laboratory experiments are integrated. In the first chapter the literature on the sources, occurrence and sinks of halogenated acetic acids (HAAs), which are phytotoxic, and probably related to forest dieback, is summarized. They are ubiquitous in precipitations and are accumulated in coniferous needles. Next to anthropogenic sources there have also been indications of a natural biotic formation of HAAs in soil. In the following main segment experiments on the abiotic formation of HAAs in soils are presented. This process is probably due to a coupled oxidation/halogenation of organic matter. Experiments with soils, humic acid and phenolic model compounds show that HAAs are generated abiotically. In the case of ethoxyphenol, this occurs through the oxidation of a C2-unit, and in the case of the other model substances probably through the breakdown of the aromatic ring system. More dichloroacetic acid (DCA) than trichloroacetic acid (TCA) is formed. The addition of iron and H2O2 leads to a further increase in formation of HAAs. Probably a Fenton reaction (Fe(II) + H2O2 -> Fe(III) + OH. + OH-) occurs between the iron and the H2O2, forming OH radicals which oxidize the Cl-, leading to the chlorination of organic matter. In the forth chapter the formation of OH radicals, measured by the 2-deoxy-D-ribose method, in aquatic systems with humic acid or soil is investigated; neither sunlight, nor the addition of H2O2 or iron is required. The in vitro formation of OH radicals increases linearly with the amount of soil or humic acid employed. In the fifth chapter the abiotic formation of alkyl iodides in soil is studied. Soils, humic acid and model substances were employed. Similar to the formation of HAAs, two reaction pathways are possible: either, in the case of guiacol, the splitting off of a methyl group and/or the fragmentation of an aromatic system. Probably an oxidation of organic matter with iron is induced. An addition of iron leads to an increase of the production of homologous alkyl iodides from C1 to C4; this confirms the redox-induced mechanism of this reaction. In summary the results of this study indicate that organohalogen compounds are produced abiotically in soil. Their formation is dependent on environmental conditions, e.g. iron content, pH and organic carbon (Corg)

The behaviours of lighweight foamed concrete beam with different size of square hollow section

Lightweight foamed concrete is one type of concrete that can be a replacement for conventional concrete which is widely used in construction industry nowadays. High density of conventional concrete makes structural elements heavier compare to the lightweight foamed concrete. Using lightweight foamed concrete as other alternatives to replace the conventional concrete will make the concrete more lighter and by addition of making a hollow section along the beam, it can reduce more weight of concrete itself. The main purposes of this study are to examine the behaviour of beam in term of flexural strength, deflection propagated and crack pattern. The size of beam used in this study is 1 5Ox200x3000mm. Four type of sample with different size of square hollow have been used. The sample A with no hollow, sample B with size 45x45rnjn of hollow size, sample C with size 60x6Omm of hollow size and sample D 7Ox7Omm of hollow size and it been placed along the length of beam. The density of lightweight foamed concrete was 1600kg/m3 with 1:2 of water cement ratio and 1:3 for water sand ratio. The testing that involved in this study is four point flexural tests. The result shows that the flexural strength of the samples reduced due to the different size of square hollow section. The flexural was reduced to 21.85% for Beam B, 22.01% for Beam C and 28.78% for Beam D respectively. Result for deflection shows that hollow beam was having more deflection compared to solid beam. As for deflection profile at a constant loading , Beam A, Beam B, Beam C and Beam D show the same profile but with different value of maximum deflection which is 8.96mm, 9.37mm, 10.14nim and 12.13mm. Cracking pattern result shows same behaviour which is crack at shear and in inclined pattern. First crack loading result for Beam A, Beam B, Beam C and Beam D was 16.2kN, 1 l.29kN, 10.24kN, and 8.72kN respectively

The peroxisome: still a mysterious organelle.

More than half a century of research on peroxisomes has revealed unique features of this ubiquitous subcellular organelle, which have often been in disagreement with existing dogmas in cell biology. About 50 peroxisomal enzymes have so far been identified, which contribute to several crucial metabolic processes such as beta-oxidation of fatty acids, biosynthesis of ether phospholipids and metabolism of reactive oxygen species, and render peroxisomes indispensable for human health and development. It became obvious that peroxisomes are highly dynamic organelles that rapidly assemble, multiply and degrade in response to metabolic needs. However, many aspects of peroxisome biology are still mysterious. This review addresses recent exciting discoveries on the biogenesis, formation and degradation of peroxisomes, on peroxisomal dynamics and division, as well as on the interaction and cross talk of peroxisomes with other subcellular compartments. Furthermore, recent advances on the role of peroxisomes in medicine and in the identification of novel peroxisomal proteins are discussed.Supported by the German Research Foundation (DFG) (SCHR 518/6-1) and the Portuguese Foundation for Science and Technology (FCT) (PTDC/BIA-BCM/71932/2006)

al-Attas’ philosophy of history on the arrival and proliferation of Islam in the Malay world

This article examines the philosophy of history of Syed Muhammad Naquib al-Attas on the theory of the arrival and spread of Islam in the Malay world, particularly in his work ‘Historical Facts and Fictions’. This philosophy of history is consequent to al-Attas' critical research contained in his previous works such as ‘Preliminary Statement on a General Theory of The Islamization of the Malay-Indonesian Archipelago’ (1969), ‘Islam in the Malay History and Culture’ (1972) and ‘The Correct Date of the Terengganu Inscription’ (1972). This study analyses these works and his other works to look into the aspects of history and historiography contained in the philosophy of history of al-Attas on the arrival and spread of Islam in the Malay world in terms of their scope, sources and history methods. This study found that in terms of epistemology al-Attas has contributed in creating a theoretical framework and a novel approach to the philosophy of history of the history of Islam in the Malay world

Declining incidence of esophageal cancer in the Turkmen Plain, eastern part of the Caspian Littoral of Iran: A retrospective cancer surveillance

Background: Previous studies have shown that upper gastrointestinal cancers are the most common cancers in Caspian Littoral, and rate of esophageal cancer (EC) in Iranian Turkmens residing in the Eastern part of littoral are among the highest in the world. Our aim was to reassess the rate 30 years later and following socioeconomic changes in the region. Methods: A comprehensive retrospective search was undertaken to find all new cancer cases during the 1996-2000 period. Diagnosis of cancer was based on histopathological reports in 68.2, clinical and/or radiological evidence in 29.7 and death certificate only (DCO) in 2.1 of the cases. Results: A total of 5143 new cancer cases were registered of whom 3063 (59.6) were males. The median (IQR) age was 60 (44-69) years. Age-standardized rates (ASR) for all cancers in males and females were 134.7 and 104.5 per 100,000, respectively. Based on ASR, the top five common cancers in males (excluding skin cancer) were cancers of esophagus (43.4), stomach (27.8), colorectal (10.7), bladder (7.8) and oral cavity (6.3), while in females cancer of esophagus (36.3) was followed by cancers of breast (15.7), stomach (8.3) colorectal (6.6) and cervix (3.6). Conclusion: We conclude that EC incidence rate has decreased to less than half the rate reported 30 years ago, while the incidence rates of colorectal and breast cancers have increased significantly. © 2006 International Society for Preventive Oncology. Published by Elsevier Ltd. All rights reserved

Diffusing-wave spectroscopy in a standard dynamic light scattering setup

Diffusing-wave spectroscopy (DWS) extends dynamic light scattering measurements to samples with strong multiple scattering. DWS treats the transport of photons through turbid samples as a diffusion process, thereby making it possible to extract the dynamics of scatterers from measured correlation functions. The analysis of DWS data requires knowledge of the path length distribution of photons traveling through the sample. While for flat sample cells this path length distribution can be readily calculated and expressed in analytical form; no such expression is available for cylindrical sample cells. DWS measurements have therefore typically relied on dedicated setups that use flat sample cells. Here we show how DWS measurements, in particular DWS-based microrheology measurements, can be performed in standard dynamic light scattering setups that use cylindrical sample cells. To do so we perform simple random-walk simulations that yield numerical predictions of the path length distribution as a function of both the transport mean free path and the detection angle. This information is used in experiments to extract the mean-square displacement of tracer particles in the material, as well as the corresponding frequency-dependent viscoelastic response. An important advantage of our approach is that by performing measurements at different detection angles, the average path length through the sample can be varied. For measurements performed on a single sample cell, this gives access to a wider range of length and time scales than obtained in a conventional DWS setup. Such angle-dependent measurements also offer an important consistency check, as for all detection angles the DWS analysis should yield the same tracer dynamics, even though the respective path length distributions are very different. We validate our approach by performing measurements both on aqueous suspensions of tracer particles and on solidlike gelatin samples, for which we find our DWS-based microrheology data to be in good agreement with rheological measurements performed on the same samples

Global, regional, and national consumption levels of dietary fats and oils in 1990 and 2010: a systematic analysis including 266 country-specific nutrition surveys

Objectives: To quantify global consumption of key dietary fats and oils by country, age, and sex in 1990 and 2010. Design: Data were identified, obtained, and assessed among adults in 16 age- and sex-specific groups from dietary surveys worldwide on saturated, omega 6, seafood omega 3, plant omega 3, and trans fats, and dietary cholesterol. We included 266 surveys in adults (83% nationally representative) comprising 1 630 069 unique individuals, representing 113 of 187 countries and 82% of the global population. A multilevel hierarchical Bayesian model accounted for differences in national and regional levels of missing data, measurement incomparability, study representativeness, and sampling and modelling uncertainty. Setting and population Global adult population, by age, sex, country, and time. Results: In 2010, global saturated fat consumption was 9.4%E (95%UI=9.2 to 9.5); country-specific intakes varied dramatically from 2.3 to 27.5%E; in 75 of 187 countries representing 61.8% of the world’s adult population, the mean intake was <10%E. Country-specific omega 6 consumption ranged from 1.2 to 12.5%E (global mean=5.9%E); corresponding range was 0.2 to 6.5%E (1.4%E) for trans fat; 97 to 440 mg/day (228 mg/day) for dietary cholesterol; 5 to 3,886 mg/day (163 mg/day) for seafood omega 3; and <100 to 5,542 mg/day (1,371 mg/day) for plant omega 3. Countries representing 52.4% of the global population had national mean intakes for omega 6 fat ≥5%E; corresponding proportions meeting optimal intakes were 0.6% for trans fat (≤0.5%E); 87.6% for dietary cholesterol (<300 mg/day); 18.9% for seafood omega 3 fat (≥250 mg/day); and 43.9% for plant omega 3 fat (≥1,100 mg/day). Trans fat intakes were generally higher at younger ages; and dietary cholesterol and seafood omega 3 fats generally higher at older ages. Intakes were similar by sex. Between 1990 and 2010, global saturated fat, dietary cholesterol, and trans fat intakes remained stable, while omega 6, seafood omega 3, and plant omega 3 fat intakes each increased. Conclusions: These novel global data on dietary fats and oils identify dramatic diversity across nations and inform policies and priorities for improving global health