Rapid detection of white spot syndrome virus (WSSV) of Penaeus monodon by latex agglutination test using monoclonal antibodies

Latex beads were sensitized with monoclonal antibodies (MAb) rose against VP28 of WSSV. The optimum concentration of MAb required to sensitize the latex beads was 125 µg/ml. The sensitized latex beads were used to detect WSSV from PCR-positive stomach tissue homogenates obtained from infected shrimp. Stomach tissue homogenates from WSSV-infected shrimp agglutinated the sensitized latex beads within 10 minutes, while uninfected samples did not produce any agglutination, although non-specific agglutinations were observed in some samples. The analytical sensitivity, analytical specificity, diagnostic sensitivity and diagnostic specificity of the (LAT) agglutination test were assessed. The analytical sensitivity of the test was 40 ng of purified WSSV (2 µg/ml). The sensitized latex beads did not agglutinate with normal shrimp tissue or MBV-infected tissue homogenate. The test has a diagnostic sensitivity of 70 and 45%, respectively, compared to single-step and nested PCR. The diagnostic specificity of the test was 82%. This test is a simple and rapid on-farm test which can be used to corroborate clinical signs for the detection of WSSV in grow-out ponds.

Investigation of the dilution process for measurement of particulate matter from spark-ignition engines

Measurements of particulate matter (PM) from spark ignition (SI) engine exhaust using dilution tunnels will become more prevalent as emission standards are tightened. Hence, a study of the dilution process was undertaken in order to understand how various dilution related parameters affect the accuracy with which PM sizes and concentrations can be determined. A SI and a compression ignition (CI) engine were separately used to examine parameters of the dilution process; the present work discusses the results in the context of SI exhaust dilution. A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution, number density, and volume fraction of PM. Temperature measurements in the exhaust pipe and dilution tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52°C. Measurements of PM concentrations as a function of dilution ratio show the competing effects of temperature and particle/vapor concentrations on particle growth dynamics, which result in a range of dilution ratios-from 13 to 18-where the effect of dilution ratio, independent of flowrate, is kept to a minimum. This range of dilution ratios is therefore optimal in order to achieve repeatable PM concentration measurements. Particle dynamics during transit through the tunnel operating at the optimal dilution ratio was found statistically insignificant compared to data scatter. Such small differences in number concentration may be qualitatively representative of particle losses for SI exhaust, but small increases in PM volume fraction during transit through the tunnel may significantly underestimate accretion of mass due to unburned hydrocarbons (HCs) emitted by SI engines. The fraction of SI-derived PM mass due to adsorbed/absorbed vapor, estimated from these data, is consistent with previous chemical analyses of PM. © 1998 Society of Automotive Engineers, Inc.

Measurement of 5-day biochemical oxygen demand without sample dilution or bacterial and nutrient enhancement

A direct method for measuring the 5-day biochemical oxygen demand (BODS) of aquaculture samples that does not require sample dilution or bacterial and nutrient enrichment was evaluated. The regression coefficient (R-2) between the direct method and the standard method for the analyses of 32 samples from catfish ponds was 0.996. The slope of the regression line did not differ from 1.0 or the Y-intercept from 0.0 at P = 0.05. Thus, there was almost perfect agreement between the two methods. The control limits (three standard deviations of the mean) for a standard solution containing 15 mg/L each of glutamic acid and glucose were 17.4 and 20.4 mg/L. The precision of the two methods, based on eight replicate analyses of four pond water samples did not differ at P = 0.05. (c) 2005 Elsevier B.V All rights reserved.

Impacts of hydrogen dilution on growth and optical properties of a-SiC : H films

Hydrogenated amorphous silicon-carbon (a-SiC:H) films were deposited by plasma enhanced chemical vapor deposition (PECVD) with a fixed methane to silane ratio ([CH4]/[SiH4]) of 1.2 and a wide range of hydrogen dilution (R-H=[H-2]/[SiH4 + CH4]) values of 12, 22, 33, 102 and 135. The impacts of RH on the structural and optical properties of the films were investigated by using UV-VIS transmission, Fourier transform infrared (FTIR) absorption, Raman scattering and photoluminescence (PL) measurements. The effects of high temperature annealing on the films were also probed. It is found that with increasing hydrogen dilution, the optical band gap increases, and the PL peak blueshifts from similar to1.43 to 1.62 eV. In annealed state, the room temperature PL peak for the low R-H samples disappears, while the PL peak for the high R-H samples appears at similar to 2.08 eV, which is attributed to nanocrystalline Si particles confined by Si-C and Si-O bonds.

The compact microcrystalline Si thin film with structure uniformity in the growth direction by hydrogen dilution profile

The hydrogen dilution profiling (HDP) technique has been developed to improve the quality and the crystalline uniformity in the growth direction of mu c-Si:H thin films prepared by hot-wire chemical-vapor deposition. The high H dilution in the initial growth stage reduces the amorphous transition layer from 30-50 to less than 10 nm. The uniformity of crystalline content X-c in the growth direction was much improved by the proper design of hydrogen dilution profiling which effectively controls the nonuniform transition region of Xc from 300 to less than 30 nm. Furthermore, the HDP approach restrains the formation of microvoids in mu c-Si: H thin films with a high Xc and enhances the compactness of the film. As a result the stability of mu c-Si: H thin films by HDP against the oxygen diffusion, as well as the electrical property, is much improved. (c) 2005 American Institute of Physics.

Impact of hydrogen dilution on microstructure and optoelectronic properties of silicon films deposited using tirisilane

We explored the deposition of hydrogenated amorphous silicon (a-Si: H) using trisilane (Si3H8) as a gas precursor in a radiofrequency plasma enhanced chemical vapour deposition process and studied the suitability of this material for photovoltaic applications. The impact of hydrogen dilution on the deposition rate and microstructure of the films is systematically examined. Materials deposited using trisilane are compared with that using disilane (Si2H6). It is found that when using Si3H8 as the gas precursor the deposition rate increases by a factor of similar to 1.5 for the same hydrogen dilution (R = [H-2]/[Si3H8] or [H-2]/[Si2H6])- Moreover, the structural transition from amorphous to nanocrystalline occurs at a higher hydrogen dilution level for Si3H8 and the transition is more gradual as compared with Si2H6 deposited films. Single-junction n-i-p a-Si: H solar cells were prepared with intrinsic layers deposited using Si3H8 or Si2H6. The dependence of open circuit voltage (V-oc) on hydrogen dilution was investigated. V-oc greater than 1 V can be obtained when the i-layers are deposited at a hydrogen dilution of 180 and 100 using Si3H8 and Si2H6, respectively.

High quality microcrystalline Si films by hydrogen dilution profile

Novel hydrogen dilution profiling (HDP) technique was developed to improve the uniformity in the growth direction of mu c-Si:H thin films prepared by hot wire chemical vapor deposition (HWCVD). It was found that the high H dilution ratio reduces the incubation layer from 30 nm to less than 10 nm. A proper design of hydrogen dilution profiling improves the uniformity of crystalline content, X-c, in the growth direction and restrains the formation of micro-voids as well. As a result the compactness of mu c-Si:H films with a high crystalline content is enhanced and the stability of mu c-Si:H thin film against the oxygen diffusion is much improved. Meanwhile the HDP mu c-Si:H films exhibit the low defect states. The high nucleation density from high hydrogen dilution at early stage is a critical parameter to improve the quality of mu c-Si:H films. (c) 2006 Published by Elsevier B.V.

High quality microcrystalline Si films by hydrogen dilution profile

Novel hydrogen dilution profiling (HDP) technique was developed to improve the uniformity in the growth direction of mu c-Si:H thin films prepared by hot wire chemical vapor deposition (HWCVD). It was found that the high H dilution ratio reduces the incubation layer from 30 nm to less than 10 nm. A proper design of hydrogen dilution profiling improves the uniformity of crystalline content, X-c, in the growth direction and restrains the formation of micro-voids as well. As a result the compactness of mu c-Si:H films with a high crystalline content is enhanced and the stability of mu c-Si:H thin film against the oxygen diffusion is much improved. Meanwhile the HDP mu c-Si:H films exhibit the low defect states. The high nucleation density from high hydrogen dilution at early stage is a critical parameter to improve the quality of mu c-Si:H films. (c) 2006 Published by Elsevier B.V.

Vulcanization of polybutadiene latex induced by Co-60 gamma radiation

Polybutadiene latex (PBL) vulcanization induced by Co-60 radiation and the influence of dose on crosslinking were investigated. Morphology and particle size distribution were examined by AFM and a particle size analyzer. The casting films were characterized for their swelling and mechanical properties as a function of dose.

Effect of annealing on the deformation mechanism of a styrene/n-butyl acrylate copolymer latex film investigated by synchrotron small-angle X-ray scattering

The deformation mechanism of a styrene/n-butyl acrylate copolymer latex film subjected to uniaxial tensile stress was studied by small-angle X-ray scattering. The influence of annealing at 23, 60, 80, and 100 degrees C for 4 h on microscopic deformation processes was elucidated. It was demonstrated that the microscopic deformation mechanism of the latex films transformed gradually from nonaffine deformation behavior to affine deformation behavior with increasing annealing temperature.

In Situ Observation of Tensile Deformation Processes of Soft Colloidal Crystalline Latex Fibers

The deformation mechanism or styrene/n-butyl acrylate copolymer latex films with fiber symmetric crystalline structure subjected to uniaxial stretching was studied using synchrotron small-angle X-ray scattering technique. The fibers were drawn at angles or 0, 35, and 55 degrees with respect to the Fiber axis. In all cases, the microscopic deformation within the crystallites was Found to deviate from affine deformation behavior with respect to the macroscopic deformation ratio. Moreover, the extent of this deviation is different in the three cases. This peculiar behavior can be attributed to the relative orientation of the (111) plane of the crystals, the plane of densest packing, with respect to the stretching direction in each case. When the stretching direction coincides with the crystallographic (111) plane, which is the case for stretching directions of 0 and 55 degrees with respect to the fiber axis, the microscopic deformation deviates less from affine behavior than when the stretching direction is arbitrarily oriented with respect to the crystallographic (111) plan.

GIUSAXS and AFM Studies on Surface Reconstruction of Latex Thin Films during Thermal Treatment

The structural evolution of a single-layer latex film during annealing was studied via grazing incidence ultrasmall-angle X-ray scattering (GIUSAXS) and atomic force microscopy (AFM). The latex particles were composed of a low-T-g (-54 degrees C) core (n-butylacrylate, 30 wt %) and a high-T-g (41 degrees C) shell (t-butylacrylate, 70 wt %) and had an overall diameter of about 500 nm. GIUSAXS data indicate that the q(y) scan at q(z) = 0.27 nm(-1) (out-of-plane scan) contains information about both the structure factor and the form factor. The GIUSAXS data on latex films annealed at various temperatures ranging from room temperature to 140 degrees C indicate that the structure of the latex thin film beneath the surface changed significantly. The evolution of the out-of-plane scan plot reveals the surface reconstruction of the film. Furthermore, we also followed the time-dependent behavior of structural evolution when the latex film was annealed at a relatively low temperature (60 degrees C) where restructuring within the film can be followed that cannot be detected by AFM, which detects only surface morphology.

DEFORMATION OF SOFT COLLOIDAL CRYSTALLINE STRUCTURE - THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCES BY SYNCHROTRON SMALL-ANGLE X-RAY SCATTERING ON TENSILE STRETCHED POLYMERIC LATEX FILM

Films obtained via drying a polymeric latex dispersion are normally colloidal crystalline where latex particles are packed into a face centered cubic (fcc) structure. Different from conventional atomic crystallites or hard sphere colloidal crystallites, the crystalline structure of these films is normally deformable due to the low glass transition temperature of the latex particles. Upon tensile deformation, depending on the drawing direction with respect to the normal of specific crystallographic plane, one observes different crystalline structural changes. Three typical situations where crystallographic c-axis, body diagonal or face diagonal of the fcc structure of the colloidal crystallites being parallel to the stretching direction were investigated.

Facile synthesis of polyaniline nanofibers using pseudo-high dilution technique

A new approach for the synthesis of polyaniline nanofibers under pseudo-high dilute conditions in aqueous system has been developed. High yield nanoscale polyaniline fibers with 18-110 nm in diameter are readily prepared by a high aniline concentration 0.4 M oxidation polymerization using ammonium persulfate (APS) as an oxidant in the presence of hydrochloric acid (HCl), perchloric acid (HClO4), (1S)-(+)-10-camphorsulfonic acid (CSA), acidic phosphate PAEG120 (PA120) and sulfuric acid (H2SO4) as the dopants. The novel pathway always produces polyaniline nanofibers of tunable diameters, high conductivity (from 10(0) to 10(1) S/cm) and crystallinity.