Involvement of a 70-kb plasmid of the epidemic Shigella dysenteriae type 1 (Dt66) strain in drug-resistance, lipopolysaccharide synthesis, and virulence

During recent years home ventilation has been shown to be useful for a growing number of patients with neuromuscular diseases and respiratory insufficiency caused by weakness of the respiratory muscles. Despite its technical simplicity, home ventilation leads to a number of social, ethical, medical and infrastructural problems. This consensus paper discusses the special situation of patients with neuromuscular diseases in home ventilation and describes the current thinking in the following topics: (1) definition of home ventilation; (2) aims of home ventilation; (3) indications and preconditions of home ventilation; (4) techniques and forms of home ventilatory support; (5) preparation for and practical questions of home ventilation; (6) stopping home ventilation.     

Variations in the subunit content and catalytic activity of the cytochrome c oxidase complex from different tissues and different cardiac compartments

The objective of this study was to fully characterize normosmic perception of stimuli expected to cause widely varying degrees of olfactory and nasal trigeminal stimulation and to directly evaluate the possible role of olfactory nerve stimulation in nasal irritation sensitivity. During each of four identical test sessions, four anosmic and 31 normosmic participants were presented with a range of concentrations extending from peri-threshold for normosmics to supra-threshold for anosmics. For each session, odor (O) and nasal irritation (NI) sensitivities were summarized in terms of the concentrations required to produce four sensation levels ('iso-response' concentrations). Within-participant variation in these iso-response concentrations was < 10-fold for 95% of normosmics, for both O and NI. For O but not NI, these apparent fluctuations in sensitivity were largely accounted for by the uncertainty surrounding the iso-response concentrations calculated for each session. Anosmics exhibited minimal within- and between-participant variation in NI and required, for all but the highest perceptual level, a higher concentration than almost all normosmics. Between-participant variation, expressed in terms of 90% confidence interval widths, was approximately 0.5 log units for both O and NI for the highest perceptual level, but increased to approximately 0.8 and 1.8 log units, respectively, for the lowest (peri-threshold) level. Our findings suggest that: (i) most apparent variation over time in O sensitivity is actually a reflection of the uncertainty surrounding estimates of sensitivity obtained for each session; (ii) within- and between-participant variation in O sensitivity is far less than is commonly reported; and (iii) low to moderate levels of NI in normosmics are the result of relatively weak trigeminal stimulation combined with much greater olfactory activation.     

Load dependent fretting wear properties of 3Y-TZP nanoceramics

Despite the fact that the processing of nanoceramics composites have been triggered to a great extent, the evaluation of their potential in engineering application is rather limited. To this end, the present work reports the results obtained with fretting wear (mode I, linear tangential displacement sliding) of Y-TZP nanoceramics, optimally densified using spark plasma sintering route. The tribological experiments were conducted by varying normal load (2–10N) for 100,000 fretting cycles with relative displacement stroke of 50 μm at a frequency of 8 Hz. Based on the investigation of the topographical features of worn surfaces, the mechanism of material removal has been proposed. An important finding is that TZP nanoceramic/steel tribocouple exhibit an increase in COF from 0.2 to 0.5 as well as severe wear damage with increase in load from 2N to 5N and above, under the selected experimental conditions.     

Factors influencing primary productivity in Panshet and Ujjani Reservoirs, India

Nitrogen and phosphorus concentrations and their ratios are important factors influencing the primary productivity of a reservoir. Based on analyses of Panshet and Ujjani Reservoirs in Maharashtra, India, it was observed that, in addition to their nitrogen and phosphorus concentrations and ratios and other chemical constituents, physiographical factors such as geography, catchment land use, water basin morphology, bathymetry and changing water levels or flushing rates also influenced the productivity of these two reservoirs.     

Improved sliding wear-resistance of alumina with sub-micron grain size: A comparison with coarser grained material

Un-lubricated sliding wear behaviour of sub-micron grained (average grain size, G = 0.45 μm), self-mated alumina was studied using conformal-contact with a unidirectional pin-on-disc wear testing machine. The wear characteristics of higher grained alumina samples (G = 0.95 and 4 μm) are also studied under self mating condition for comparative analysis by using similar test parameters and identical test configuration. Sub-micron grained alumina exhibits substantially higher wear resistance compared to the alumina of larger grain size. Scanning electron microscopy of the worn out test samples reveals that in un-lubricated condition, compaction of wear debris on sliding surface governs the wear characteristics of the present set of alumina. In many cases, partly revealed intergranular fracture was noticed. The strength of adhesion of the compacted wear debris with sliding surface increases with decreasing grain size. In case of alumina of larger grain size, the stability of the compacted layer decreases due to cracking. For sub-micron grained alumina, compacted layer of debris with increased adherence efficiently protects the virgin material resulting substantial decrease in wear loss.     

Synthesis of boron nitride

The authors examine the boric oxide—ammonia route with special stress on the yield and composition of the intermediate addition compound (BN) _x (B₂O₃) _y (NH₃) _z . It has been concluded that B₂O₃ and NH₃ present in the addition compound formed between 350°C and 900°C cannot be further reacted to convert the B₂O₃ into BN and the BN yield remains at around 66%. A formula (BN)_12·7(B₂O₃)_7·5NH₃ has been suggested for the addition compound.     

Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram‐Positive Staphylococci

The emergence of multidrug resistant bacteria, especially biofilm‐associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine‐monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10^?6m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol‐stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm‐associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%–90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections.     

Effect of different loss mechanisms in SiGeSn based mid-infrared laser

We have analyzed the mid-infrared SiGeSn based Barrier-Well-Barrier Heterostracture and calculated the transparency carrier density and corresponding current density for the structure. The effects of different loss mechanisms like free carrier absorption, spontaneous recombination and Auger recombination processes on the transparency current density have been examined. It is shown that, the transparency current density increases significantly with the injected carrier density. Different scattering processes like acoustic phonon scattering and intervalley optical phonon scattering are taken into consideration for this analysis of free carrier absorption mechanisms.

     

Numerical investigations of flat punch molding using a higher order strain gradient plasticity theory

In this work we have revisited the problem of molding a deformable substrate with a rigid flat punch. The work is motivated by the recent experiments by Chen et al. (Acta Mater 59:1112?1120, 2011) where it was shown that systematically determined characteristic molding pressure H increased significantly with decrease in punch width, for widths less than \(\sim 25 \; \mu m\) . This size effect, akin to the indentation size effect observed in nano-indentation of metals, assumes importance in applications involving molding of metallic microstructures. Numerical simulations have been conducted within the framework of a finite deformation higher order strain gradient model. While classical plasticity predicts almost uniform stress with severe plastic strain concentration at the sharp corners to prevail just beneath the punch, our simulations present a significantly different picture. Very narrow punches have fairly uniform plastic strain with severe concentration of strain gradients and large contact stresses close to the edges. Wider punches however, behave in a manner closely resembling the predictions of classical plasticity.