A highly oxidized graphite oxide was synthesized from natural graphite powder by oxidation with KMnO
4 in concentrated H
2SO
4 followed by hydrolysis, washing and centrifugation. Concentrated ...gel-like colloidal dispersions were obtained. The corresponding filtrates, supernatants, GO dispersions, and solid GO films obtained from them, were investigated by various chemical analyses, small angle X-ray scattering, X-ray diffraction, light scattering (LS), Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy,
13C Nuclear Magnetic Resonance and Thermo-Gravimetric Analysis. The spectroscopic analysis shows besides the common peaks assigned to water molecules, hydroxyl and carboxyl groups, elimination of C
C bonds due to strong oxidation and presence of bands assigned to sulfate. Data of Gas Chromatography/Mass Spectrometry experiments confirm the presence in GO of water and an abundance of carboxyl groups. Scattering measurements confirm that the structure of the GO colloids consists of plate-like objects, mostly containing only a few layers, with a small population of thicker aggregates. SEM images of cross sections of dried GO film, obtained by freeze fracture, demonstrate that a continuous film-like structure was successfully achieved by elimination of water localized within exfoliated GO particles in the swelled GO aqueous colloidal dispersions.
One of the most salient features of Bacillus subtilis and related bacilli is their natural capacity to secrete a variety of proteins into their environment, frequently to high concentrations. This ...has led to the commercial exploitation of bacilli as major "cell factories" for secreted enzymes. The recent sequencing of the genome of B. subtilis has provided major new impulse for analysis of the molecular mechanisms underlying protein secretion by this organism. Most importantly, the genome sequence has allowed predictions about the composition of the secretome, which includes both the pathways for protein transport and the secreted proteins. The present survey of the secretome describes four distinct pathways for protein export from the cytoplasm and approximately 300 proteins with the potential to be exported. By far the largest number of exported proteins are predicted to follow the major "Sec" pathway for protein secretion. In contrast, the twin-arginine translocation "Tat" pathway, a type IV prepilin-like export pathway for competence development, and ATP-binding cassette transporters can be regarded as "special-purpose" pathways, through which only a few proteins are transported. The properties of distinct classes of amino-terminal signal peptides, directing proteins into the various protein transport pathways, as well as the major components of each pathway are discussed. The predictions and comparisons in this review pinpoint important differences as well as similarities between protein transport systems in B. subtilis and other well-studied organisms, such as Escherichia coli and the yeast Saccharomyces cerevisiae. Thus, they may serve as a lead for future research and applications.
To investigate the impact of urinary incontinence (UI) on health-related quality of life (QOL), as measured by the Medical Outcomes Study Short Form-36 (SF-36) and to compare UI and non-UI elderly ...Medicare beneficiaries enrolled in managed care plans on the prevalence of depression and self-rated health.
After excluding beneficiaries younger than 65 years old, a total of 141 815 completed surveys were used for analysis. The survey included 1 question on difficulty in controlling urination, 3 questions on depression, 3 questions on health, a series of questions regarding comorbid medical conditions, and the SF-36. Self-rated health, prevalence of depression, and scores in each domain of QOL were compared between UI and non-UI groups.
Overall, the prevalence of UI was 24.7% (20.9% in men, 27.5% in women). The UI group was about twice as likely to feel depressed as the non-UI group. The UI group also rated their health more negatively. Compared with continent respondents, those who were incontinent had lower standardized scores on all 8 subscales of SF-36 as well as 2 summary scores. Results from multiple regressions indicated that UI had a significantly negative impact on all aspects of QOL after adjusting for comorbidities and demographic differences.
Findings indicate that elderly patients with UI are more depressed and have worse perceived health. On certain domains of QOL, the negative impact of UI even surpasses that of other severe comorbidities.
In this study, we compared the early fish colonization of three types of artificial reefs deployed in the coastal waters of Saba and St Eustatius in the Caribbean: reef balls®, layered cakes and ...piles of locally obtained basaltic rock. As an indicator of performance, three fish assemblage parameters (abundance, biomass, species richness) were measured using underwater visual censuses at 11 months post-deployment and 4 months after restoration from hurricane damage. All artificial reef plots showed higher values for fish abundance, biomass and species richness than control plots covered by bare sand, which shows that artificial reefs can locally enhance the fish assemblage. However, the effect differed among artificial reef plots. Fish abundance was 3.8 times higher on the layered cake plots compared to the reef ball plots, while fish biomass was 4.6 times higher. Rock pile plots had intermediate values. Species richness did not differ significantly among different artificial reef plots. Three-dimensional modelling revealed that layered cakes had a smaller gross volume, shelter volume and total surface area than reef balls. The availability of multiple small shelters in the layered cake design appeared to be more relevant than other physical parameters, as the layered cake plots had higher fish abundance than the reef balls plots. We concluded that on Saba and St. Eustatius, layered cake plots performed better than reef ball plots after one year of colonization. Rock pile plots, made of local volcanic rock, showed an intermediate performance, and were 4–10 times cheaper to construct. If observed differences are consistent with other locations and persist during further colonization, current efforts to deploy reef balls could better be allocated to deploy artificial reef structures with a higher shelter density.
•Fish abundance and biomass differed per artificial reef type.•This difference is driven by the availability of small shelters.•Artificial reef deployment can be more efficient by choosing better performing or cheaper designs.
The discovery that proteins exported from the cytoplasm are typically synthesized as larger precursors with cleavable signal peptides has focused interest on the peptidases that remove the signal ...peptides. Here, we review the membrane‐bound peptidases dedicated to the processing of protein precursors that are found in the plasma membrane of prokaryotes and the endoplasmic reticulum, the mitochondrial inner membrane, and the chloroplast thylakoidal membrane of eukaryotes. These peptidases are termed type I signal (or leader) peptidases. They share the unusual feature of being resistant to the general inhibitors of the four well‐characterized peptidase classes. The eukaryotic and prokaryotic signal peptidases appear to belong to a single peptidase family. This review emphasizes the evolutionary concepts, current knowledge of the catalytic mechanism, and substrate specificity requirements of the signal peptidases.
► We studied debris and tar contamination on 21 natural beach sites in Bonaire. ► Highest debris and tar contamination was found on windward beaches. ► Beach litter contamination levels are high in ...the Southeastern Caribbean. ► Coastal categories differed significantly in terms of debris characteristics.
Data on beach debris and tar contamination is provided for 21 natural beach sites in Bonaire, Southeastern Caribbean. Transects amounting to a combined length of 991m were sampled March–May 2011 and a total of 8960 debris items were collected. Highest debris and tar contamination were found on the beaches of the windward east-coast of the island where geometric mean debris concentrations (± approx. 70% confidence limits) were 115±58itemsm−1 and 3408±1704gm−1 of beach front. These levels are high compared to data collected almost 20years earlier on the nearby island of Curaçao. Tar contamination levels averaged 223gm−1 on windward beaches. Contamination levels for leeward west-coast beaches were generally two orders of magnitude less than windward beaches.
Magnesium hydroxide is extensively used in the plastics industry as a flame retardant and smoke suppressant in various polymeric matrices (polyolefins, nylons etc.). However, it was found that ...compounding Mg(OH)
2 with polymers leads to the formation of various colours ranging from light grey to rather dark beige. The effect of the temperature and processing technology, and of various properties of Mg(OH)
2 (impurities, particle size and morphology) on colour formation was investigated in this work. One of the causes for the discolouration appears to be the interaction between the Mg(OH)
2 and antioxidants containing phenolic groups. This reaction takes place rapidly when the former is added to the polymer melt containing the antioxidant. The amount and type of coating, and its continuity over the particles surface (dependent on the powder morphology and coating technology) may represent a way to prevent the chemical interaction between the filler and plastics components and avoid discolouration. A method for the quantitative evaluation of coating quality and continuity was developed. Based on this research, ways to improve the quality of magnesium hydroxide as a fire retardant were suggested. One of these ways, namely the addition of TiO
2, is particularly interesting. We found that besides its pigmentation effect, TiO
2 is synergistic with magnesium hydroxide in terms of flame retardancy and improves the thermal stability of polypropylene.
Since the recent detection of an astrophysical flux of high-energy neutrinos, the question of its origin has not yet fully been answered. Much of what is known about this flux comes from a small ...event sample of high neutrino purity, good energy resolution, but large angular uncertainties. In searches for point-like sources, on the other hand, the best performance is given by using large statistics and good angular reconstructions. Track-like muon events produced in neutrino interactions satisfy these requirements. We present here the results of searches for point-like sources with neutrinos using data acquired by the IceCube detector over 7 yr from 2008 to 2015. The discovery potential of the analysis in the northern sky is now significantly below = 10−12 TeV cm−2 s−1, on average 38% lower than the sensitivity of the previously published analysis of 4 yr exposure. No significant clustering of neutrinos above background expectation was observed, and implications for prominent neutrino source candidates are discussed.
PDF
