Low Temperature Raman Spectra of Dichlorosulfane (SC12), Tetrachlorosulfurane (SC14), Dichlorodisulfane (S2C12) and Dichlorodiselane (Se2Cl2) [1]

The Raman spectrum of commercial "sulfur dichloride" shows strong lines due to SCl2 and S2Cl2 and weak Cl2 lines at 25 °C, but strong SCl2 and SCl4 signals at -100 °C (the latter are superimposed on the S2Cl2 lines). Thus, the intense Raman effect of SCl4 can be used to detect small amounts of chlorine in SCl2 . Mixtures of SCl2 and Cl2 (1:15) yield the Raman spectrum of SCl4 at -140 °C, while at 25 °C not trace of this compound can be detected. The spectra of SCl4 and α-SeCl4 are quite different, indicating different molecular and/or crystal structures, although ECl3 + ions (E = S, Se) are present in both cases. While Se2Cl2 dimerizes reversibly below -50 °C, S2Cl2 neither dimerizes nor isomerizes on cooling. The S2Cl2 dimer is characterized by a Raman line at 215 cm-1 the intensity of which was used to calculate an enthalpy of dimerization as of -17 kJ/mol

embCAB Sequence Variation Among Ethambutol-Resistant Mycobacterium Tuberculosis Isolates Without embB306 Mutation

Mechanisms of resistance to ethambutol in Mycobacterium tuberculosis remain inadequately described. Although there is mounting evidence that mutations of codon 306 in embB play a key role, a significant number of phenotypically ethambutol-resistant strains do not carry mutations in this codon. Here, other mutations in the embCAB operon are suggested to be involved in resistance development

Estimating Emission Control Costs: A Comparison of the Approaches Implemented in the EC-EFOM-ENV and the IIASA-RAINS Models

The paper introduces two major model approaches to estimate emission control costs and develops a methodology to introduce results of energy flow optimization models (such as EFOM-ENV) into models for integrated assessment of acidification control strategies (such as the RAINS model). Based on a reference scenario for West Germany, national cost curves for reductions of SO2 and NOx emissions derived by both the EFOM-ENV and the RAINS model are compared. It is shown that -- as long as changes in the energy structure are excluded as means for reducing emissions -- results obtained from these models are comparable and the reasons for differences can be traced back to different input assumptions. However, as soon as energy conservation and fuel-substitution are utilized to reduce emissions, the simplified approach implemented in the RAINS model results in an overestimation of emission control costs

Innovative diagnostic methods to detect harmful wood-inhabiting insects

Eine nicht-invasive Diagnose holzzerstörender Schadorganismen ist von großer Bedeutung um Eingriffe in kostbare Holzprodukte und lebende Bäume auf ein Minimum zu beschränken. Hier stellen wir zwei ganz unterschied­liche Methoden vor, eine physikalische und eine molekularbiologische, die einen schonenden Nachweis von Insekten­larven im Holz ermöglichen. Beide Methoden sind bereits zum Teil erfolgreich zur Analyse des Asiatischen Laubholzbockkäfers (Anoplophora glabripennis, ALB) eingesetzt worden und eignen sich als Frühwarnsysteme in der Bekämpfung von Quarantäneschadinsekten.Non-invasive diagnosis of harmful wood-inhabiting orga­nisms is of great importance in order to minimize interventions in valuable wood products and living trees. Here we present two methods, an acoustical and a molecular one, which enable gentle detection of insect larvae in wood and wood products. In parts, both methods have been successfully applied for the analysis of the Asian longhorn beetle (Anoplophora glabripennis, ALB) and appear suitable as early warning systems in the control of quarantine insect pests

Genomic Diversity among Drug Sensitive and Multidrug Resistant Isolates of Mycobacterium tuberculosis with Identical DNA Fingerprints

complex (MTBC), the causative agent of tuberculosis (TB), is characterized by low sequence diversity making this bacterium one of the classical examples of a genetically monomorphic pathogen. Because of this limited DNA sequence variation, routine genotyping of clinical MTBC isolates for epidemiological purposes relies on highly discriminatory DNA fingerprinting methods based on mobile and repetitive genetic elements. According to the standard view, isolates exhibiting the same fingerprinting pattern are considered direct progeny of the same bacterial clone, and most likely reflect ongoing transmission or disease relapse within individual patients.We generated 23.9 million (K-1) and 33.0 million (K-2) paired 50 bp purity filtered reads corresponding to a mean coverage of 483.5 fold and 656.1 fold respectively. Compared with the laboratory strain H37Rv both Beijing isolates shared 1,209 SNPs. The two Beijing isolates differed by 130 SNPs and one large deletion. The susceptible isolate had 55 specific SNPs, while the MDR variant had 75 specific SNPs, including the five known resistance-conferring mutations. isolates exhibiting identical DNA fingerprinting patterns can harbour substantial genomic diversity. Because this heterogeneity is not captured by traditional genotyping of MTBC, some aspects of the transmission dynamics of tuberculosis could be missed or misinterpreted. Furthermore, a valid differentiation between disease relapse and exogenous reinfection might be impossible using standard genotyping tools if the overall diversity of circulating clones is limited. These findings have important implications for clinical trials of new anti-tuberculosis drugs

High Resolution Discrimination of Clinical Mycobacterium tuberculosis Complex Strains Based on Single Nucleotide Polymorphisms

Recently, the diversity of the Mycobacterium tuberculosis complex (MTBC) population structure has been described in detail. Based on geographical separation and specific host pathogen co-evolution shaping MTBC virulence traits, at least 20 major lineages/genotypes have evolved finally leading to a clear influence of strain genetic background on transmissibility, clinical presentation/outcome, and resistance development. Therefore, high resolution genotyping for characterization of strains in larger studies is mandatory for understanding mechanisms of host-pathogen-interaction and to improve tuberculosis (TB) control. Single nucleotide polymorphisms (SNPs) represent the most reliable markers for lineage classification of clinical isolates due to the low levels of homoplasy, however their use is hampered either by low discriminatory power or by the need to analyze a large number of genes to achieve higher resolution. Therefore, we carried out de novo sequencing of 26 genes (approx. 20000 bp per strain) in a reference collection of MTBC strains including all major genotypes to define a highly discriminatory gene set. Overall, 161 polymorphisms were detected of which 59 are genotype-specific, while 13 define deeper branches such as the Euro-American lineage. Unbiased investigation of the most variable set of 11 genes in a population based strain collection (one year, city of Hamburg, Germany) confirmed the validity of SNP analysis as all strains were classified with high accuracy. Taken together, we defined a diagnostic algorithm which allows the identification of 17 MTBC phylogenetic lineages with high confidence for the first time by sequencing analysis of just five genes. In conclusion, the diagnostic algorithm developed in our study is likely to open the door for a low cost high resolution sequence/SNP based differentiation of the MTBC with a very high specificity. High throughput assays can be established which will be needed for large association studies that are mandatory for detailed investigation of host-pathogen-interaction during TB infection

Study of the particle motion induced by a vortex shaker

The behaviour of a traced alumina particle lying on limestone powders with similar features has been studied in a test tube agitated by a vortex shaker aiming at studying dust emissions from powders. PEPT (Positron Emission Particle Tracking) was used for measuring the particle's position. Population densities were computed as the frequency of the particle's presence in different regions dividing the two horizontal axes and the vertical axis, respectively. The velocities of the particle were calculated by filtering out all displacements inferior to a critical distance dcrit so as not to consider spurious movements caused by experimental noise. After its validation, the methodology was applied to the standard condition of a vortex shaker experiment (ω = 1500 rpm, 2 g of powder and open test tube). While the horizontal coordinates and velocity components follow a symmetric distribution, the vertical coordinate is characterised by a large asymmetrical plateau. The heights reached by the particle (up to 24.3 mm) are small in comparison to that of the test tube (150 mm). The greatest velocities are found near the inner wall of the test tube and at the highest heights where the population densities are the lowest. The median velocity of the particle is 0.0613 m.s −1 whereas its median kinetic energy is 8.4E-12 J. The method explicated in the present study is directly applicable to any other sets of data obtained through PEPT, especially if the system is of small dimension

Current Issues on Molecular and Immunological Diagnosis of Tuberculosis

Laboratory diagnosis of tuberculosis (TB) traditionally relies on smear microscopy and culture of Mycobacterium tuberculosis from clinical samples. With recent advances in technology, there have been numerous efforts to develop new diagnostic tests for TB that overcome the low sensitivity and specificity and long turnover time associated with current diagnostic tests. Molecular biological tests based on nucleic acid amplification have brought an unprecedented opportunity for the rapid and specific detection of M. tuberculosis from clinical specimens. With automated sequencing analysis, species identification of mycobacteria is now easier and more accurate than with conventional methods, and rapid detection of mutations in the genes associated with resistance to TB drugs provides early information on the potential drug resistance for each clinical isolate or for clinical samples. In addition, immunological tests for the detection of M. tuberculosis antigens and antibodies to the antigens have been explored to identify individuals at risk of developing TB or with latent TB infection (LTBI). The recent introduction of commercial IFN-γ assay kits for the detection of LTBI provides a new approach for TB control even in areas with a high incidence of TB. However, these molecular and immunological tools still require further evaluation using large scale cohort studies before implementation in TB control programs