Electrodeposition of platinum nanoclusters on type I collagen modified electrode and its electrocatalytic activity for methanol oxidation

We firstly reported a novel polymer matrix fabricated by type I collagen and polymers, and this matrix can be used as nanoreactors for electrodepositing platinum nanoclusters (PNCs). The type I collagen film has a significant effect on the growth of PNCs. The size of the platinum nanoparticles could be readily tuned by adjusting deposition time, potential and the concentration of electrolyte, which have been verified by field-emitted scanning electron microscopy (FE-SEM). Furthermore, cyclic voltammetry (CV) has demonstrated that the as-prepared PNCs can catalyze methanol directly with higher activity than that prepared on PSS/PDDA film, and with better tolerance to poisoning than the commercial E-TEK catalyst. The collagen-polymer matrix can be used as a general reactor to electrodeposit other metal nanostructures.

Electrochemiluminescent determination of glucose with a sol-gel derived ceramic-carbon composite electrode as a renewable optical fiber biosensor

A sol-gel derived ceramic-carbon composite electrode is used for fabrication of a new type of optical fiber biosensor based on luminol electrochemiluminescence (ECL). The electrode consists of graphite powder impregnated with glucose oxidase in a silicate network. In this configuration, the immobilized enzyme oxidizes glucose to liberate hydrogen peroxide and graphite powder provides percolation conductivity for triggering the ECL between luminol and the liberated hydrogen peroxide. Both of the reactions occur simultaneously on the surface of the composite electrode, thereby the response of the biosensor is very fast. The peak intensity was achieved within only 20 s after glucose injection. In addition, the electrode could be renewed by a simple mechanical polishing step in case of contamination or fouling. The linear range extends from 0.01 to 10 mM for glucose and the detection limit is about 8.16 muM. The renewal repeatability and stability of the biosensor are also investigated in detail.

Experimental Studies of the Coherence of Microstructure-Fiber Supercontinuum

The phase coherence of supercontinuum generation in microstructure fiber is quantified by performing a Young's type interference experiment between independently generated supercontinua from two separate fiber segments. Analysis of the resulting interferogram yields the wavelength dependence of the magnitude of the mutual degree of coherence, and a comparison of experimental results with numerical simulations suggests that the primary source of coherence degradation is the technical noise-induced fluctuations in the injected peak power. © 2003 Optical Society of America.

Iron abundances from optical FeIII absorption lines in B-type stellar spectra

The role of optical FeIII absorption lines in B-type stars as iron abundance diagnostics is considered. To date, ultraviolet Fe lines have been widely used in B-type stars, although line blending can severely hinder their diagnostic power. Using optical spectra, covering a wavelength range ~3560-9200Å, a sample of Galactic B-type main-sequence and supergiant stars of spectral types B0.5 to B7 are investigated. A comparison of the observed FeIII spectra of supergiants, and those predicted from the model atmosphere codes TLUSTY [plane-parallel, non-local thermodynamic equilibrium (LTE)], with spectra generated using SYNSPEC (LTE), and CMFGEN (spherical, non-LTE), reveal that non-LTE effects appear small. In addition, a sample of main-sequence and supergiant objects, observed with the Fiber-fed Extended Range Optical Spectrograph (FEROS), reveal LTE abundance estimates consistent with the Galactic environment and previous optical studies. Based on the present study, we list a number of FeIII transitions which we recommend for estimating the iron abundance from early B-type stellar spectra.

Abnormal integrity of association fiber tracts in amnestic mild cognitive impairment.

The association fiber tracts integrity of the inter-hemispheric and within-hemispheric communication was poor understood in amnestic type mild cognitive impairment (aMCI) patients by diffusion tensor imaging (DTI). A region of interest-based DTI approach was applied to explore fiber tract differences between 22 aMCI patients and 22 well-matched normal aging. Correlations were also sought between fractional anisotropy (FA) values and the cognitive performance scores in the aMCI patients. Extensive impairment of association fiber tracts integrity was observed in aMCI patients, including bilateral inferior fronto-occipital fascicles, the genu of corpus callosum, bilateral cingulate bundles and bilateral superior longitudinal fascicles II (SLE II) subcomponent. In addition, the FA value of right SLE II was significantly negatively correlated to the performance of Trail Making Test A and B, whilst the values of right posterior cingulate bundle was significantly positive correlation with MMSE score. As aMCI is a putative prodromal syndrome to Alzheimer's disease (AD), this study suggested that investigation of association fiber tracts between remote cortexes may yield important new data to predict whether a patient will eventually develop AD.

Nerve pathology in the type 1 diabetic dog: effects of treatment with sulindac

The purpose of this study was to define pathological abnormalities in the peripheral nerve of a large animal model of long-duration type 1 diabetes and also to determine the effects of treatment with sulindac. Detailed morphometric studies were performed to define nerve fiber and endoneurial capillary pathology in 6 control dogs, 6 type 1 diabetic dogs treated with insulin, and 6 type 1 diabetic dogs treated with insulin and sulindac for 4 years. Myelinated fiber and regenerative cluster density showed a non-significant trend toward a reduction in diabetic compared to control animals, which was prevented by treatment with sulindac. Unmyelinated fiber density did not differ among groups. However, diabetic animals showed a non-significant trend toward an increase in axon diameter (p <0.07), with a shift of the size frequency distribution towards larger axons, which was not prevented by treatment with sulindac. Endoneurial capillary density and luminal area showed a non-significant trend toward an increase in diabetic animals, which was prevented with sulindac treatment. Endoneurial capillary basement membrane area was significantly increased (p <0.05) in diabetic animals, but was not prevented with sulindac treatment. We conclude that the type 1 diabetic dog demonstrates minor structural abnormalities in the nerve fibers and endoneurial capillaries of the sciatic nerve, and treatment with sulindac ameliorates some but not all of these abnormalities.

Commissioning and Evaluation of a Fiber-Optic Sensor System for Bridge Monitoring

This paper describes the design, commissioning, and evaluation of a ?ber-optic strain sensor system for the structural health monitoring of a prestressed concrete posttensioned box girder railway bridge in Mumbai, India, which shows a number of well-documented structural problems. Preliminary laboratory trials to design the most appropriate sensor system that could be readily transported and used on site are described, followed by a description of load tests on the actual bridge undertaken in collaboration with Indian Railways and using locomotives of known weight. Results from the load tests using the optical system are compared with similar results obtained using electrical resistance strain gages. Conclusions are summarized concerning the integrity of the structure and for the future use of the sensor system for monitoring bridges of this type. Crack width measurements obtained during the load tests are also described.

Synapsin- and actin-dependent frequency enhancement in mouse hippocampal mossy fiber synapses

The synapsin proteins have different roles in excitatory and inhibitory synaptic terminals. We demonstrate a differential role between types of excitatory terminals. Structural and functional aspects of the hippocampal mossy fiber (MF) synapses were studied in wild-type (WT) mice and in synapsin double-knockout mice (DKO). A severe reduction in the number of synaptic vesicles situated more than 100 nm away from the presynaptic membrane active zone was found in the synapsin DKO animals. The ultrastructural level gave concomitant reduction in F-actin immunoreactivity observed at the periactive endocytic zone of the MF terminals. Frequency facilitation was normal in synapsin DKO mice at low firing rates (approximately 0.1 Hz) but was impaired at firing rates within the physiological range (approximately 2 Hz). Synapses made by associational/commissural fibers showed comparatively small frequency facilitation at the same frequencies. Synapsin-dependent facilitation in MF synapses of WT mice was attenuated by blocking F-actin polymerization with cytochalasin B in hippocampal slices. Synapsin III, selectively seen in MF synapses, is enriched specifically in the area adjacent to the synaptic cleft. This may underlie the ability of synapsin III to promote synaptic depression, contributing to the reduced frequency facilitation observed in the absence of synapsins I and II.

A fiber optic concentration sensor

A simple fiber optic concentration sensor based on the coupling of light f rom one fiber to another through a solution is discussed. The operational characteristics of the sensor are illustrated by taking the solutions of potassium permanganate and fast green dye as samples.The extrinsic type sensor described here shows linearity at lower concentrations.

Studies on some nonlinear schrodinger type equations describing pulse propagation through optical fibers

The discovery of the soliton is considered to be one of the most significant events of the twentieth century. The term soliton refers to special kinds of waves that can propagate undistorted over long distances and remain unaffected even after collision with each other. Solitons have been studied extensively in many fields of physics. In the context of optical fibers, solitons are not only of fundamental interest but also have potential applications in the field of optical fiber communications. This thesis is devoted to the theoretical study of soliton pulse propagation through single mode optical fibers.

Loss of nerve fiber layer in HIV positive patients and comparative patterns in a series of cases in Bucaramanga, Colombia

Objective: The objective of this study is to conduct a description of the features of optic neuropathy associated with Human Immunodeficiency Virus in relation to their possible incidence within our population, regarding that there is no data in our population in terms of frequency of this pathology (1,2). Methodology: Descriptive cross-sectional study of a clinical series of patients infected with human immunodeficiency virus, but AIDS, and the thickness of optic nerve´s layer of fibers studied with OCT technology (optical coherence tomography), patients were cited once captured. OCT was performed by the same observer, by taking 3 shots and picking the one with better reliability. Patients were given personally to the Ophthalmologic Foundation of Santander to conduct the review called OCT (optical coherence tomography). Results: In terms of viral load variable, we found a clear correlation in which validates the hypothesis that lower viral load means a thicker layer of fibers finding statistically significant differences for the 6 hours in right eye and 12 and 6 hours in left eye. Comparison between the known nomogram of fiber layer thickness for the population of Bucaramanga, Santander and thickness found in our sample, we note a clear decrease in the upper and lower quadrants, specifically in 7 hours and 11 hours, being more important in 7 hours, showing statistically significant differences. Conclusions: The pattern  of thinning of the nerve fiber layer in HIV positive patients without AIDS, and antiretroviral treatment type HAART, showed a statistically significant thinning targeted at 7 hours and 11 hours, being higher in first. Viral load figures have a direct relation with loss fiber layer, showing a statistically significant difference for the 6 and 12 hours.

Structure and biogenesis of the capsular F1 antigen from Yersinia pestis: Preserved folding energy drives fiber formation

Most gram-negative pathogens express fibrous adhesive virulence organelles that mediate targeting to the sites of infection. The F1 capsular antigen from the plague pathogen Yersinia pestis consists of linear fibers of a single subunit (Caf1) and serves as a prototype for nonpilus organelles assembled via the chaperone/usher pathway. Genetic data together with high-resolution X-ray structures corresponding to snapshots of the assembly process reveal the structural basis of fiber formation. Comparison of chaperone bound Caf1 subunit with the subunit in the fiber reveals a novel type of conformational change involving the entire hydrophobic core of the protein. The observed conformational change suggests that the chaperone traps a high-energy folding intermediate of Caf1. A model is proposed in which release of the subunit allows folding to be completed, driving fiber formation.

Streptococcus castoreus sp nov., isolated from a beaver (Castor fiber)

A previously undescribed, Gram-positive, catalase-negative, Streptococcus-like organism originating from a European beaver (Castor fiber) was subjected to a taxonomic study. The organism displayed beta-haemolytic activity and gave a positive reaction with Lancefield group A antisera. Based on the results of biochemical testing, the organism was tentatively identified as a member of the genus Streptococcus, but it did not correspond phenotypically to any recognized species of this genus. Comparative 16S rRNA gene sequencing studies confirmed this assignment, with the bacterium forming a hitherto unknown subline within the genus. Sequence divergence values of greater than 3% from other reference streptococcal species, however, demonstrated that the unidentified coccus-shaped organism represents a hitherto unknown species. Based on phenotypic and molecular phylogenetic evidence, it is therefore proposed that the unknown organism from a beaver be classified as a novel species, Streptococcus castoreus sp. nov. The type strain is M605815/03/2(T) (=CCUG 48115(T) = CIP 108205(T)).

Radiometric analysis of the light coupled by optimally cut plastic optical fiber amplitude modulating reflectance displacement sensors

A radiometric analysis of the light coupled by optical fiber amplitude modulating extrinsic-type reflectance displacement sensors is presented. Uncut fiber sensors show the largest range but a smaller responsivity. Single cut fiber sensors exhibit an improvement in responsivity at the expense of range. A further increase in responsivity as well as a reduction in the operational range is obtained when the double cut sensor configuration is implemented. The double cut configuration is particularly suitable in applications where feedback action is applied to the moving reflector surface. © 2000 American Institute of Physics.

Effects of forage type and extruded linseed supplementation on methane production and milk fatty acid composition of lactating dairy cows

Replacing dietary grass silage (GS) with maize silage (MS) and dietary fat supplements may reduce milk concentration of specific saturated fatty acids (SFA) and can reduce methane production by dairy cows. The present study investigated the effect of feeding an extruded linseed supplement on milk fatty acid (FA) composition and methane production of lactating dairy cows, and whether basal forage type, in diets formulated for similar neutral detergent fiber and starch, altered the response to the extruded linseed supplement. Four mid-lactation Holstein-Friesian cows were fed diets as total mixed rations, containing either high proportions of MS or GS, both with or without extruded linseed supplement, in a 4 × 4 Latin square design experiment with 28-d periods. Diets contained 500 g of forage/kg of dry matter (DM) containing MS and GS in proportions (DM basis) of either 75:25 or 25:75 for high MS or high GS diets, respectively. Extruded linseed supplement (275 g/kg ether extract, DM basis) was included in treatment diets at 50 g/kg of DM. Milk yields, DM intake, milk composition, and methane production were measured at the end of each experimental period when cows were housed in respiration chambers. Whereas DM intake was higher for the MS-based diet, forage type and extruded linseed had no significant effect on milk yield, milk fat, protein, or lactose concentration, methane production, or methane per kilogram of DM intake or milk yield. Total milk fat SFA concentrations were lower with MS compared with GS-based diets (65.4 vs. 68.4 g/100 g of FA, respectively) and with extruded linseed compared with no extruded linseed (65.2 vs. 68.6 g/100 g of FA, respectively), and these effects were additive. Concentrations of total trans FA were higher with MS compared with GS-based diets (7.0 vs. 5.4 g/100 g of FA, respectively) and when extruded linseed was fed (6.8 vs. 5.6 g/100 g of FA, respectively). Total n-3 FA were higher when extruded linseed was fed compared with no extruded linseed (1.2 vs. 0.8 g/100 g of FA, respectively), whereas total n-6 polyunsaturated FA were higher when feeding MS compared with GS (2.5 vs. 2.1 g/100 g of FA, respectively). Feeding extruded linseed and MS both provided potentially beneficial decreases in SFA concentration of milk, and no significant interactions were found between extruded linseed supplementation and forage type. However, both MS and extruded linseed increased trans FA concentration in milk fat. Neither MS nor extruded linseed had significant effects on methane production or yield, but the amounts of supplemental lipid provided by extruded linseed were relatively small.