Laser Ultrasonic Thermoelastic/Ablation Generation with Laser Interferometric Detection in Graphite/Polymer Composites

Ultrasonic signals have been generated and detected in graphite/polymer composites by optical methods. A Doppler interferometric technique was used for detection. The output voltage of this type of interferometer is proportional to the surface velocity of a sample area which is illuminated by cw laser light. Ultrasonic signals were generated by thermoelastic and ablation processes which occur as a consequence of laser pulses incident on the opposite surface of the sample. The evolution of the magnitude and shape of the detected signals was measured as a function of the pulse energy of the generating laser. Low-energy laser pulses generated ultrasound without causing obvious surface damage. At higher energies surface damage was observable in post inspection but could also be detected by observing (through protective goggles) bright flashes near the illuminated area. The energy at which these processes first occur is qualitatively referred to as the ablation threshold. Changes in the observed waveform were evident at energies above the ablation threshold. The higher-energy waveforms were found to consist of a superposition of a thermoelastic component and an ablatic component, whose relative magnitudes changed with laser power. A delay in the initiation of the ablatic wave relative to the thermoelastic wave was observed to be of the order of 0.3 μs, consistent with observations in pure polymer. [1] Photoelectric detection measurements of the ablation plume also showed a clear threshold and a time scale for growth of the ablation products with a characteristic time scale on the order of 0.3 μs

Attomolar Detection of Botulinum Toxin Type A in Complex Biological Matrices

BACKGROUND: A highly sensitive, rapid and cost efficient method that can detect active botulinum neurotoxin (BoNT) in complex biological samples such as foods or serum is desired in order to 1) counter the potential bioterrorist threat 2) enhance food safety 3) enable future pharmacokinetic studies in medical applications that utilize BoNTs. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe a botulinum neurotoxin serotype A assay with a large immuno-sorbent surface area (BoNT/A ALISSA) that captures a low number of toxin molecules and measures their intrinsic metalloprotease activity with a fluorogenic substrate. In direct comparison with the "gold standard" mouse bioassay, the ALISSA is four to five orders of magnitudes more sensitive and considerably faster. Our method reaches attomolar sensitivities in serum, milk, carrot juice, and in the diluent fluid used in the mouse assay. ALISSA has high specificity for the targeted type A toxin when tested against alternative proteases including other BoNT serotypes and trypsin, and it detects the holotoxin as well as the multi-protein complex form of BoNT/A. The assay was optimized for temperature, substrate concentration, size and volume proportions of the immuno-sorbent matrix, enrichment and reaction times. Finally, a kinetic model is presented that is consistent with the observed improvement in sensitivity. CONCLUSIONS/SIGNIFICANCE: The sensitivity, specificity, speed and simplicity of the BoNT ALISSA should make this method attractive for diagnostic, biodefense and pharmacological applications

Impact of Dietary Gluten on Regulatory T Cells and Th17 Cells in BALB/c Mice

Dietary gluten influences the development of type 1 diabetes (T1D) and a gluten-free (GF) diet has a protective effect on the development of T1D. Gluten may influence T1D due to its direct effect on intestinal immunity; however, these mechanisms have not been adequately studied. We studied the effect of a GF diet compared to a gluten-containing standard (STD) diet on selected T cell subsets, associated with regulatory functions as well as proinflammatory Th17 cells, in BALB/c mice. Furthermore, we assessed diet-induced changes in the expression of various T cell markers, and determined if changes were confined to intestinal or non-intestinal lymphoid compartments. The gluten-containing STD diet led to a significantly decreased proportion of γδ T cells in all lymphoid compartments studied, although an increase was detected in some γδ T cell subsets (CD8+, CD103+). Further, it decreased the proportion of CD4+CD62L+ T cells in Peyer's patches. Interestingly, no diet-induced changes were found among CD4+Foxp3+ T cells or CD3+CD49b+cells (NKT cells) and CD3−CD49b+ (NK) cells. Mice fed the STD diet showed increased proportions of CD4+CD45RBhigh+ and CD103+ T cells and a lower proportion of CD4+CD45RBlow+ T cells in both mucosal and non-mucosal compartments. The Th17 cell population, associated with the development of autoimmunity, was substantially increased in pancreatic lymph nodes of mice fed the STD diet. Collectively, our data indicate that dietary gluten influences multiple regulatory T cell subsets as well as Th17 cells in mucosal lymphoid tissue while fewer differences were observed in non-mucosal lymphoid compartments

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Comment on "Structural and Electrical Properties of Atomic Layer Deposited Al-Doped ZnO Films"

In a recent report, Lee et al. have proposed an "effective field model" for extrinsic doping to explain the electrical properties of Al-doped zinc oxide (ZnO) films grown by atomic layer deposition (ALD)([1]). They have introduced the doping model by considering the layered structure of the ALD-grown films as observed in the transmission electron microscopy measurements. However, in the present comment, we have demonstrated that the suggested doping model is misleading in which physically inconsistent assumptions are considered throughout. Herein, a reasonable interpretation of the electrical properties and doping mechanism of the ALD-grown films by taking into consideration the theoretical formulations of the disordered electronic system is suggested

Low temperature and rapid deposition of ZnO nanorods on Si(100) substrate with tunable optical emissions

This research article describes the large scale fabrication of ZnO nanorods of various shapes on Si(100) substrate, by using metalorganic precursor of Zn in solutions with microwave as the source of energy. This is a low temperature, environmental friendly and rapid thin film deposition process, where ZnO nanorods (1-3 mu m length) were grown only in 1-5 min of microwave irradiation. All as-synthesized nanorods are of single crystalline grown along the < 0001 > crystallographic direction. The coated nanorods were found to be highly dense having a thickness of similar to 1-3 mu m over the entire area 20 mm x 20 mm of the substrate. The ZnO thin film comprising of nanorods exhibits good adhesion with the substrate. A possible mechanism for the initial nucleation and growth of ZnO is discussed. A cross over from a strong visible light emission to an enhanced UV emission is observed, when the nature of the surfactants are varied from polymeric to ionic and nonionic. The position of the chromaticity coordinates in yellow region of the color space gives an impression of white light generation from these coatings by exciting with a blue laser

A Novel Preweld Laser Surface Treatment for Enhanced Intergranular Corrosion Resistance of Austenitic Stainless Steel Weldments

This paper describes the development of a new prewelding laser surface melting treatment scheme to Suppress sensitization in the heat-affected zone of gas tungsten arc weldment of Type 304 stainless steel. The results of the present study, performed on 6-mm-thick medium-carbon (0.044 wt-%) and 10-mm-thick high-carbon (0.1 wt-%) Type 304 stainless steel sheets, established that surface modification engineered by CO(2) laser treatment is highly effective in suppressing heat-affected zone sensitization during subsequent gas tungsten arc welding. Laser surface treated heat-affected zone of gas tungsten are weldment exhibited a significantly lower degree of sensitization and susceptibility to intergranular corrosion than those of untreated heat-affected zone. This is attributed to higher fraction of Sigma 1 subgrain boundaries introduced by laser-assisted melting and resolidification