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A propylsulfonic acid-derivatized mesoporous SBA-15 catalyst was examined for activity and selectivity in the dehydrocondensation of methanol and isobutanol to form ethers, principally methyl isobutyl ether (MIBE) and dimethyl ether (DME), and dehydration of isobutanol to olefins, at elevated temperatures and pressures. It was shown that the catalyst maintained activity for > 1600 h , and the Bronsted acid sites corresponding to 1 meq/g of catalyst were stable under these reaction conditions until they were deliberately in situ poisoned by addition of pyridine. X-ray photoelectron spectroscopy (XPS) revealed that the pyridine was selectively and strongly adsorbed on the sulfonic acid groups. Kinetic studies demonstrated that MIBE and DME were formed by surface-catalyzed S N 2 reactions that follow Langmuir–Hinshelwood kinetics involving competitive adsorption of the alcohols, while isobutene formation utilizes a vacant Bronsted acid site adjacent to the adsorbed isobutanol molecule. Isobutene formation rate exhibited a distinct maximum as a function of the alcohol pressure. This kinetic behavior is similar to that observed with Nafion-H and other catalysts. Because of the high apparent activation energy of isobutene synthesis compared with the much lower apparent activation energies of the ethers, lower reaction temperatures along with higher reactant pressures favor the formation of ethers over olefins. Theoretical modeling of the reaction pathway located stationary points including the transition states (TS) with barrier energies for all reactions involved, and showed that for ether synthesis one alcohol was adsorbed on a sulfonic acid site (I) via a donor H bond while the second alcohol was adsorbed on a proximal sulfonic acid site (II) via an acceptor H bond. In the intermediate, methyl transfer from the adsorbed methanol to the isobutanol oxygen occurs to form MIBE. At the same time, isobutanol donates its proton to a sulfonic acid group (II) whose oxygen acts as a base, and the methanol OH group accepts a proton from a sulfonic acid group (I) and is split off as water. To balance the surface charge, the original proton on sulfonic acid group (II) is transferred to sulfonic acid group (I), and MIBE is desorbed. The flexibility of the TS involving the concerted movement of all three protons is essential for the connectivity of the TS with the reactants and products and the umbrella inversion of the methyl group during its transfer. The theory has thus not only yielded a picture that is fully consistent with observed isotope flows, sp 3 carbon inversion, and temperature/pressure-dependent selectivity, but also revealed unprecedented detail of the concerted proton transfer and the role of acid–base interactions in this dual-site catalysis.

The authors hypothesized a self-fulfilling prophecy wherein rejection expectancies lead people to behave in ways that elicit rejection from their dating partners. The hypothesis was tested in 2 studies of conflict in couples: (a) a longitudinal field study where couples provided daily-diary reports and (b) a lab study involving behavioral observations. Results from the field study showed that high rejection-sensitive (HRS) people's relationships were more likely to break up than those of low rejection-sensitive (LRS) people. Conflict processes that contribute to relationship erosion were revealed for HRS women but not for HRS men. Following naturally occurring relationship conflicts, HRS women's partners were more rejecting than were LRS women's partners. The lab study showed that HRS women's negative behavior during conflictual discussions helped explain their partners' more rejecting postconflict responses.

International audience; Aspergillus fumigatus is exceptional among microorganisms in being both a primary and opportunistic pathogen as well as a major allergen. Its conidia production is prolific, and so human respiratory tract exposure is almost constant. A. fumigatus is isolated from human habitats and vegetable compost heaps. In immunocompromised individuals, the incidence of invasive infection can be as high as 50% and the mortality rate is often about 50% (ref. 2). The interaction of A. fumigatus and other airborne fungi with the immune system is increasingly linked to severe asthma and sinusitis. Although the burden of invasive disease caused by A. fumigatus is substantial, the basic biology of the organism is mostly obscure. Here we show the complete 29.4-megabase genome sequence of the clinical isolate Af293, which consists of eight chromosomes containing 9,926 predicted genes. Microarray analysis revealed temperature-dependent expression of distinct sets of genes, as well as 700 A. fumigatus genes not present or significantly diverged in the closely related sexual species Neosartorya fischeri, many of which may have roles in the pathogenicity phenotype. The Af293 genome sequence provides an unparalleled resource for the future understanding of this remarkable fungus.

Saturated thalassic brines are among the most physically demanding habitats on Earth: few microbes survive in them. Salinibacter ruber is among these organisms and has been found repeatedly in significant numbers in climax saltern crystallizer communities. The phenotype of this bacterium is remarkably similar to that of the hyperhalophilic Archaea (Haloarchaea). The genome sequence suggests that this resemblance has arisen through convergence at the physiological level (different genes producing similar overall phenotype) and the molecular level (independent mutations yielding similar sequences or structures). Several genes and gene clusters also derive by lateral transfer from (or may have been laterally transferred to) haloarchaea. S. ruber encodes four rhodopsins. One resembles bacterial proteorhodopsins and three are of the haloarchaeal type, previously uncharacterized in a bacterial genome. The impact of these modular adaptive elements on the cell biology and ecology of S. ruber is substantial, affecting salt adaptation, bioenergetics, and photobiology.

Staphylococcus aureus is an opportunistic pathogen and the major causative agent of numerous hospital- and community-acquired infections. Staphylococcus epidermidis has emerged as a causative agent of infections often associated with implanted medical devices. We have sequenced the ∼2.8-Mb genome of S. aureus COL, an early methicillin-resistant isolate, and the ∼2.6-Mb genome of S. epidermidis RP62a, a methicillin-resistant biofilm isolate. Comparative analysis of these and other staphylococcal genomes was used to explore the evolution of virulence and resistance between these two species. The S. aureus and S. epidermidis genomes are syntenic throughout their lengths and share a core set of 1,681 open reading frames. Genome islands in nonsyntenic regions are the primary source of variations in pathogenicity and resistance. Gene transfer between staphylococci and low-GC-content gram-positive bacteria appears to have shaped their virulence and resistance profiles. Integrated plasmids in S. epidermidis carry genes encoding resistance to cadmium and species-specific LPXTG surface proteins. A novel genome island encodes multiple phenol-soluble modulins, a potential S. epidermidis virulence factor. S. epidermidis contains the cap operon, encoding the polyglutamate capsule, a major virulence factor in Bacillus anthracis . Additional phenotypic differences are likely the result of single nucleotide polymorphisms, which are most numerous in cell envelope proteins. Overall differences in pathogenicity can be attributed to genome islands in S. aureus which encode enterotoxins, exotoxins, leukocidins, and leukotoxins not found in S. epidermidis .

Metformin (1,1-dimethylbiguanide) is an antihyperglycaemic drug used to normalize glucose concentrations in type 2 diabetes. Furthermore, antioxidant benefits have been reported in diabetic patients treated with metformin. This work was aimed at studying the scavenging capacity of this drug against reactive oxygen species (ROS) like *OH and (O2*-)-free radicals. ROS were produced by gamma radiolysis of water. The irradiated solutions of metformin were analyzed by UV/visible absorption spectrophotometry. It has been shown that hydroxyl free radicals react with metformin in a concentration-dependent way. The maximum scavenging activity was obtained for concentrations of metformin > or = 200 micromol.L(-1), under our experimental conditions. An estimated value of 10(7) L.mol(-1).s(-1) has been determined for the second order rate constant k(*OH + metformin). Superoxide free radicals and hydrogen peroxide do not initiate any oxidation on metformin in our in vitro experiments.

The complete genome sequence of Geobacter sulfurreducens , a δ-proteobacterium, reveals unsuspected capabilities, including evidence of aerobic metabolism, one-carbon and complex carbon metabolism, motility, and chemotactic behavior. These characteristics, coupled with the possession of many two-component sensors and many c-type cytochromes, reveal an ability to create alternative, redundant, electron transport networks and offer insights into the process of metal ion reduction in subsurface environments. As well as playing roles in the global cycling of metals and carbon, this organism clearly has the potential for use in bioremediation of radioactive metals and in the generation of electricity.

The complete genome sequence of Enterococcus faecalis V583, a vancomycin-resistant clinical isolate, revealed that more than a quarter of the genome consists of probable mobile or foreign DNA. One of the predicted mobile elements is a previously unknown vanB vancomycin-resistance conjugative transposon. Three plasmids were identified, including two pheromone-sensing conjugative plasmids, one encoding a previously undescribed pheromone inhibitor. The apparent propensity for the incorporation of mobile elements probably contributed to the rapid acquisition and dissemination of drug resistance in the enterococci.

The motility characteristics of natural assemblages of coastal marine bacteria were examined. Initially, less than 10% of the bacteria were motile. A single addition of tryptic soy broth caused an increase in the motile fraction of cells but only after 7 to 12 h. Motility peaked at 15 to 30 h, when more than 80% of cells were motile. These results support the proposal that energy limits motility in the marine environment. Cell speeds changed more than an order of magnitude on timescales of milliseconds and hours. The maximum community speed was 144 (mu)m s(sup-1), and the maximum individual burst velocity was 407 (mu)m s(sup-1). In uniform medium, speed was an inverse function of tryptic soy broth concentration, declining linearly over 0.001 to 1.0%. In media where concentration gradients existed, the mean speed was a function of position in a spatial gradient, changing from 69 to 144 (mu)m s(sup-1) over as little as 15 to 30 (mu)m. The results suggest that marine bacteria are capable of previously undescribed quick shifts in speed that may permit the bacteria to rapidly detect and keep up with positional changes in small nutrient sources. These high speeds and quick shifts may reflect the requirements for useful motility in a turbulent ocean.

Castor bean is an important oil-producing plant in the Euphorbiaceae family. Its high-quality oil contains up to 90% of the unusual fatty acid ricinoleate, which has many industrial and medical applications. Castor bean seeds also contain ricin, a highly toxic Type 2 ribosome-inactivating protein, which has gained relevance in recent years due to biosafety concerns. In order to gain knowledge on global genetic diversity in castor bean and to ultimately help the development of breeding and forensic tools, we carried out an extensive chloroplast sequence diversity analysis. Taking advantage of the recently published genome sequence of castor bean, we assembled the chloroplast and mitochondrion genomes extracting selected reads from the available whole genome shotgun reads. Using the chloroplast reference genome we used the methylation filtration technique to readily obtain draft genome sequences of 7 geographically and genetically diverse castor bean accessions. These sequence data were used to identify single nucleotide polymorphism markers and phylogenetic analysis resulted in the identification of two major clades that were not apparent in previous population genetic studies using genetic markers derived from nuclear DNA. Two distinct sub-clades could be defined within each major clade and large-scale genotyping of castor bean populations worldwide confirmed previously observed low levels of genetic diversity and showed a broad geographic distribution of each sub-clade.

Buttermilk powder and meat meal were compared as sources of protein in the concentrate mixture fed to Jersey calves early weaned from milk on to pasture. Complete replacement of buttermilk powder with meat meal did not affect the intake of concentrates or the growth rate of calves but reduced the costs of supplementary concentrate feeding by over 25%.

Forty Friesian bull calves were reared by the “restricted whole milk and early weaning concentrate mixture” method. The daily allowance of milk was offered in two equal feeds at 7.00 a.m. and 4 p.m. to 20 animals in one group and in a single feed at 7.00 a.m. to the 20 remaining calves in the other group. Both groups grew at similar rates and consumed the same amount of concentrate during the pre- and post-weaning periods.

Four groups of Friesian bull calves, each containing nine animals, were reared to the age of 14 weeks on different levels of whole milk— 12%, 15%, and 18% of body weight, and to appetite, to Groups A, B, C, and D respectively. Calves in Group A consumed their ration throughout the trial period. Intakes declined following the age of six weeks in Groups C and D and after 10 weeks in Group B. The decline was greatest in Group D and least in Group B. Growth rate increased with advancing age while animals were on full rations. Total live weight gain over the entire 14-week period rose with increasing level of intake. Feed conversion for the 14-week period did not differ between groups, although increases were noted after the age of 10 weeks in Group A, eight weeks in Group B, and six weeks in Groups C and D. Scours were most prevalent before the fourth and after the eighth week of age. During the first four weeks of life scours appeared to be microbial in nature, and after the eighth week of age were ...

To the Editor. —I would like to share this experience with your readers. A 71-year-old patient who had an intraocular lens in the right eye four years ago had progressive but painless loss of vision of one month's duration. On examination, his visual acuity was 20/200. The left eye had a corneal transplant, and the visual acuity was never better than 20/400. The right eye was mildly hyperemic. There was marked corneal edema in the upper nasal quadrant. The anterior chamber was deep and clear. A loose 10-0 nylon suture was sticking out of the intraocular lens and touching the endothelium, resulting in the corneal edema. Before attempting to cut the suture with an argon laser beam, I tried it on a sample suture. It was cut very easily using a (300 mW, 100μm) couple of pulses. However, when the suture was immersed in normal saline solution in a