AIMS: To investigate and compare the bactericidal activity (BA) of active bromine and chlorine compounds in the absence and presence of protein load. METHODS AND RESULTS: Quantitative killing tests ...against Escherichia coli and Staphylococcus aureus were performed both in the absence and in the presence of peptone with pairs of isosteric active chlorine and bromine compounds: hypochlorous and hypobromous acid (HOCl and HOBr), dichloro‐ and dibromoisocyanuric acid, chlorantine and bromantine (1,3‐dibromo‐ and 1,3 dichloro‐5,5‐dimethylhydantoine), chloramine T and bromamine T (N‐chloro‐ and N‐bromo‐4‐methylbenzenesulphonamide sodium), and N‐chloro‐ and N‐bromotaurine sodium. To classify the bactericidal activities on a quantitative basis, an empirical coefficient named specific bactericidal activity (SBA), founded on the parameters of killing curves, was defined: Formula: see text In the absence of peptone, tests with washed micro‐organisms revealed a throughout higher BA of bromine compounds with only slight differences between single substances. This was in contrast to chlorine compounds, whose killing times differed by a factor of more than four decimal powers. As a consequence, also the isosteric pairs showed according differences. In the presence of peptone, however, bromine compounds showed an increased loss of BA, which partly caused a reversal of efficacy within isosteric pairs. CONCLUSIONS: In medical practice, weakly oxidizing active chlorine compounds like chloramines have the highest potential as topical anti‐infectives in the presence of proteinaceous material (mucous membranes, open wounds). Active bromine compounds, on the other hand, have their chance at insensitive body regions with low organic matter, for example skin surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: The expected protein load is one of the most important parameters for selection of a suited active halogen compound.
The kissing bugs—Triatoma rubida (Uhler), Triatoma protracta (Uhler), and Triatoma recurva (Stal)—are common hematophagous bugs in southeastern Arizona and responsible for severe allergic reactions ...in some individuals who are bitten. They also possess the potential to transmit the blood parasite, Trypanosoma cruzi. We previously found the essential oil, citronella, to be an excellent deterrent of feeding of T. rubida on a restrained mouse. In this work, we tested major components—alcohols, aldehydes, and monoterpenes—of citronella oil for repellency against the three common triatome species endemic in southern Arizona. The following citronella oil components—geraniol, citronellol, limonene, and citronellal—in different concentrations and combinations were tested. All components of citronella oil demonstrated some inhibition of feeding, ranging from very weak inhibition (limonene) to significant inhibition (geraniol and citronellol). A mixture of geraniol and citronellol was found to be repellant at concentrations of .165 and .165 vol%, respectively, for all three triatome species. Citronellal and limonene had no significant repellent activity. The repellent activity of citronella oil appears to be acting through direct contact with the bugs rather than diffusion of vapors.
The compression behavior of deuterated ice VII and VIII was investigated by high pressure neutron scattering in the pressure range 2–13.7 GPa between 93 and 300 K. We establish equations of state ...which contain accurate values for the bulk moduli B0, their pressure derivatives B′0, as well as the ambient pressure volume V0. These equations of state hold over a large part of the stability domain of ice VII, by comparison with available x-ray data, and to at least ≈ 13 GPa for ice VIII. They are indistinguishable at low pressures, but beyond ≈ 7 GPa and at low temperatures ice VIII appears to become stiffer than expected. This might be related to an anomalous phonon hardening observed previously in ice VIII in this P/T range D. D. Klug et al., Phys. Rev. B 70, 144113 (2004).
A species' ecological niche depends on the species' adaptations to its present habitat, but also on the legacy from its ancestors. Most authors argue that such a phylogenetic niche conservatism is of ...minor importance, although no quantitative analyses across a major taxon is available. Higher plants from central Europe offer a unique opportunity for such an exercise, as the niche positions along various environmental gradients are available for most species. We quantified niche conservatism by two approaches. First, we used a phylogenetic tree and quantified the degree of retention of niches across the tree. Depending on the gradient, the values ranged from 0.43 to 0.22. This was significantly greater than the null expectation. Second, we used a taxonomy and quantified the amount of variance among species that could be explained at higher taxonomic levels. The values ranged from 25 to 72%. Again, this was significantly higher than the null expectation. Thus, both approaches indicated a clear niche conservatism. The distribution of conservatism across taxonomic levels differed considerably among environmental gradients. The differences among environmental gradients could be correlated with the palaeoenvironmental conditions during the radiation of the phylogenetic lineages. Thus, niche conservatism among extant plant species may reflect the opportunities of their ancestors during their diversification.
The kissing bug, Triatoma rubida (Uhler) is a common hematophagous bug in Tucson, AZ, and is responsible for causing severe allergic reactions in some bitten individuals. DEET, picaridin, tea tree ...oil, peppermint oil, and citronella oil were tested for repellency to T. rubida and its ability to probe and feed on a small restrained rat. No long range repellency was observed with any of the test materials. The lowest repellent concentrations observed were: 10% DEET, 7% picaridin; 30% tea tree oil, 3.3% peppermint oil, and 0.165% citronella oil. Only citronella oil was able to stop all probing and feeding by T. rubida. Citronella oil appears to be a promising potential repellent to prevent sleeping people from being bitten by kissing bugs.
Embrittlement of steels and alloys in contact with hydrogen gas under pressure is a key problem in metallurgy with important implications for a future energy economy based on hydrogen. Here we report ...stress-strain measurements recorded under 200 MPa (∼30,000 PSI) hydrogen gas pressure to evaluate the resistance of MP35N to embrittlement. We find that MP35N with a tensile strength of more than 1800 MPa does not suffer any strength loss, retains a significant amount of ductility and hence appears to be highly resistant to hydrogen embrittlement even under elevated stress when exposed over a time-scale of hours. This exceptional resistance to H-embrittlement seems to be unique among all high-performance steels and alloys of comparable strength and bears on the use of this material for high pressure H
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research devices and storage applications.
It has been known for decades that certain aqueous salt solutions of LiCl and LiBr readily form glasses when cooled to below ≈160 K. This fact has recently been exploited to produce a « salty » ...high-pressure ice form: When the glass is compressed at low temperatures to pressures higher than 4 GPa and subsequently warmed, it crystallizes into ice VII with the ionic species trapped inside the ice lattice. Here we report the extreme limit of salt incorporation into ice VII, using high pressure neutron diffraction and molecular dynamics simulations. We show that high-pressure crystallisation of aqueous solutions of LiCl∙RH2O and LiBr∙RH2O with R = 5.6 leads to solids with strongly expanded volume, a destruction of the hydrogen-bond network with an isotropic distribution of water-dipole moments, as well as a crystal-to-amorphous transition on decompression. This highly unusual behaviour constitutes an interesting pathway from a glass to a crystal where translational periodicity is restored but the rotational degrees of freedom remaining completely random.
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