A novel method for replacement of the dislodged tracheostomy tube: the nasogastric tube "guidewire" technique

The ready access to blood (plasma and formed cellular elements) makes it unusually susceptible to the deleterious effects of pollutants whose origins may be in the air. The red blood cells' hemoglobin may be rendered useless for oxygen transport by combination with carbon monoxide or conversion to methemoglobin or sulfhemoglobin. Lead and arsine can damage the erythrocytes' membranes, resulting in anemia. Metabolites of benzene and other volatile polycyclic hydrocarbons are implicated in the causation of leukemias. The extensive use of pesticides and herbicides may be associated with the development of Hodgkin's disease, non-Hodgkin's lymphoma, and aplastic anemia. The carcinogenic risks from ionizing radiation, especially for leukemia, are well known. More information is needed concerning the epidemiology of environmental factors responsible for damage to blood. Enhanced knowledge about the molecular biology of toxins' effects on the hematopoietic system and improved detection and prevention technologies are needed to answer environmentally related health questions.     

Molecular dynamics simulations of the whey protein {beta}-lactoglobulin

Molecular dynamics simulations have been used to model the motionsand conformational behavior of the whey protein bovine ß-lactoglobulin.Simulations were performed for the protein by itself and complexedto a single retinol ligand located in a putative interior bindingpocket. In the absence of the retinol ligand, the backbone loopsaround the opening of this ulterior pocket shifted inward topartially close off this cavity, similar to the shifts observedin previously reported molecular dynamics simulations of theuncomplexed form of the homologous retinol binding protein.The protein complexed with retinol does not exhibit the sameconformational shifts. Conformational changes of this type couldserve as a recognition signal allowing in vivo discriminationbetween the free and retinol complexed forms of the 3-lactoglobulinmolecule. The unusual bending of the single a-helix observedin the simulations of retinol binding protein were not observedin the present calculations     

Residual stress and electrical properties of Pb(Zr0.52,Ti0.48)O3 thin films RF sputtered directly on Cu foils

Polycrystalline Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films between 250 and 1000 nm thick were deposited on Cu foils via RF magnetron sputtering. Samples were crystallized ex situ between 550°C and 750°C in a low oxygen partial pressure atmosphere, pO₂, in order to avoid oxidation of the substrate. These were compared to films made on more common Pt/TiO_x/SiO₂/Si substrates also crystallized under low pO₂ conditions. The mismatch of the coefficients of thermal expansion for Cu and PZT caused large compressive residual stresses to develop in the films, whereas films on Pt‐Si experienced more moderate tensile stresses. Stress was measured using the sin²ψ method. In addition to mechanical implications, i.e., film cracking and delamination, the effect of residual stress on electrical properties is discussed. Dielectric constants of PZT were lower on Cu than on Pt/TiO_x/SiO₂/Si. This could be due either to a dead layer effect or to the residual stress imposed by the substrate. The remanent polarizations for films on Cu were between 18 and 41 μC/cm², while coercive fields were between 37 and 54kV/cm. Rayleigh analysis was used to describe the role of defects affecting domain wall mobility, as they act as pinning centers and decrease the extrinsic polarization response.     

A Strategy for Preparing Star Polymers Containing Metal–Metal Bonds Along the Polymeric Arms Using Click Chemistry

The [(η⁵-C₅H₄(CH₂)₃N₃)Mo(CO)₃]₂ dimer (3) was prepared and used to determine if the Huisgen cycloaddition reaction could be used to synthesize high molecular weight star polymers with metal–metal bonds in the arms. Several different click catalysts were examined. Cp*Ru(PPh₃)₂Cl (Cp* = η⁵-C₅(CH₃)₅) was previously shown to catalyze the formation of metal–metal bond-containing polymers using click chemistry; however, this catalyst underwent a Staudinger reaction with dimer 3 when a model coupling reaction was attempted with phenylacetylene. In order to avoid the Staudinger reaction, Cp*Ru(COD)Cl was used as the catalyst in the reaction of 3 with phenylacetylene, and coupling was observed after 14 h. Synthesis of a star polymer was attempted with 3 and 1,3,5-triethynylbenzene. Instead of coupling, Cp*Ru(COD)Cl reacted with the 1,3,5-triethynylbenzene. A third catalyst, Cu(IMes)Cl (IMes = 1,3-dimesityl-imidazol-2-ylidene) was used to couple 3 with 1,3,5-triethynylbenzene in 48 h. Both a high molecular weight polymer (M _n  = 77,000 g mol^?1) and a tripodal star core (M _n  = 1,800 g mol^?1) were successfully prepared with this catalyst.     

The characterization and chemical reactivity of powdered wool

Wool powders with various particle sizes have been produced using different milling techniques. Scanning electron microscopy (SEM) showed gradual breakdown of the fibre as it was progressively converted into powder form. Chlorination enhanced the effectiveness of subsequent air-jet milling. X-ray photoelectron spectroscopy (XPS) revealed an increase in the surface concentrations of oxygen and nitrogen, and a decrease in carbon and sulphur on conversion of the fibres into powders, as the cortex became exposed on the powder surface. An increased surface concentration of cysteic acid was observed for the chlorinated powder. Rapid uptake of dye by wool powders was observed in situations where there was virtually no uptake by the original fibre. Hydrophobic dyes were more readily sorbed than were hydrophilic dyes. The chlorination treatment led to a decrease in the sorption of acid dyes. Confocal microscopy, used in conjunction with a fluorescent stain, showed that chemicals were able to penetrate wool particles, even at room temperature. The rate and extent of uptake of dye by the finer powders were comparable to that obtained with activated charcoal, even though the surface area of the charcoal was 100 times greater.     

Continuous fixed bed biosorption of Cu2+ ions: application of a simple two parameter mathematical model

Biomass from two fungi of the Mucorales order, laboratory cultured and immobilised Rhizopus arrhizus, and industrial waste Mucor miehei, was tested for capacity to adsorb copper from solution in batch and continuous‐flow column systems. Maximum uptake levels were c 400 and 300 mmol g⁻¹ (dry weight) respectively. Immobilisation of Rhizopus arrhizus in polyvinyl formal to cell loadings of 60% (w/w) did not diminish metal uptake levels. In continuous‐flow columns both biosorbents adsorbed copper to levels equal or approaching the batch uptake values. Column breakthrough curves were fitted to a two parameter model and each of the parameters, σ and t₀ , were linearly correlated with column operating parameters. Predicted breakthrough curves agreed closely with experimental values. © 1999 Society of Chemical Industry     

Supportive friendships moderate the association between stressful life events and sexual risk taking among African American adolescents.

Objective: This study examined whether uncontrollable stressful life events were associated with sexual risk taking among adolescents across a 1-year period, and whether supportive friendships modified associations. Design: Participants were 159 sexually active African American adolescents (57% male; mean age [SD] = 17.0 [1.5] years at baseline). Participants were recruited for in-person interviews through random digit dialing in one inner-city neighborhood characterized by high rates of poverty and crime relative to the surrounding city. Main Outcome Measures: Dependent variables included substance use before sexual activity and inconsistent condom use. Results: Among adolescents who reported low levels of supportive friendships, uncontrollable stressors were associated with greater levels of sexual risk taking over time. In contrast, uncontrollable stressors were not associated with sexual risk taking among adolescents who reported high social support from friends; risk taking was typically moderate to high among these adolescents. Conclusion: Different processes may explain sexual risk taking among adolescents with varying levels of social support from friends. Adolescents with low support may be prone to engagement in health risk behavior as a stress response, while adolescents with high support may engage in risk behavior primarily due to peer socialization of risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Digital refraction distortion correction with an astigmatic coherence sensor

We demonstrate the sensing and correction of an isoplanatic refractive distortion (not lens aberrations), using the complete measurement of the partially coherent field in an aperture that the previously described astigmatic coherence sensor provides. Isoplanatic distortions, and in general distortions that do not cause energy loss, maintain the orthogonality of the coherent modes. We use the fact that a common distortion will occur to all coherent modes to separate the distortion from the source behind it, rather than requiring a reference source at a different wavelength. Digital deconvolution was performed on the full four-dimensional partially coherent field for simultaneously computing the distortion and the source intensity distribution.     

Exploiting nonacoustic sensors for speech encoding

The intelligibility of speech transmitted through low-rate coders is severely degraded when high levels of acoustic noise are present in the acoustic environment. Recent advances in nonacoustic sensors, including microwave radar, skin vibration, and bone conduction sensors, provide the exciting possibility of both glottal excitation and, more generally, vocal tract measurements that are relatively immune to acoustic disturbances and can supplement the acoustic speech waveform. We are currently investigating methods of combining the output of these sensors for use in low-rate encoding according to their capability in representing specific speech characteristics in different frequency bands. Nonacoustic sensors have the ability to reveal certain speech attributes lost in the noisy acoustic signal; for example, low-energy consonant voice bars, nasality, and glottalized excitation. By fusing nonacoustic low-frequency and pitch content with acoustic-microphone content, we have achieved significant intelligibility performance gains using the DRT across a variety of environments over the government standard 2400-bps MELPe coder. By fusing quantized high-band 4-to-8-kHz speech, requiring only an additional 116 bps, we obtain further DRT performance gains by exploiting the ear's insensitivity to fine spectral detail in this frequency region.     

Fabrication of thin-film micropolarizer arrays for visible imaging polarimetry

We describe a microfabrication process for fabricating micropolarizer devices with polarization thin film. The polarization film is less than a 0.5 mum thick and can have a polarization extinction ratio of ~330 in the visible wavelength range. A single-state micropolarizer array with polarizing pixels as small as 5 mum x 5 mum has been fabricated. A multilayer spatially multiplexed three-state micropolarizer line array with a 14.4-mum resolution has also been fabricated for visible imaging polarimetry application.