Comparison of the indirect haemagglutination and gel diffusion test for serotyping Haemophilus parasuis

The aim of this study was to compare the use of indirect haemagglutination (IHA) and gel diffusion (GD) tests for serotyping Haemophilus parasuis by the Kielstein-Rapp-Gabrielson scheme. All 15 serovar reference strains, 72 Australian field isolates, nine Chinese field isolates, and seven isolates from seven experimentally infected pigs were evaluated with both tests. With the IHA test, 14 of the 15 reference strains were correctly serotyped – with serovar 10 failing to give a titre with serovar 10 antiserum. In the GD test, 13 reference strains were correctly serotyped – with antigen from serovars 7 and 8 failing to react with any antiserum. The IHA methodology serotyped a total of 45 of 81 field isolates while the GD methodology serotyped a total of 48 isolates. For 29 isolates, the GD and IHA methods gave discordant results. It was concluded that the IHA is a good additional test for the serotyping of H. parasuis by the KRG scheme if the GD methodology fails to provide a result or shows unusual cross-reactions.

Purification of immunoglobulins from chicken sera by thiophilic gel chromatography

Immunoglobulin Y is different from most of the other immunoglobulins because it does not bind protein A or protein G. Thiophilic gel chromatography has been successfully used to purify IgY from chicken egg yolk, but the technology has not previously been used to purify IgY from serum. In this research note, we describe the optimization of T-gel chromatography for purification of IgY from serum. Data are provided on the recovery and purity of IgY obtained using potassium sulfate buffers of different concentrations. Decreasing the strength of potassium sulfate buffer from 0.5 to 0.3 M did not alter the amount of IgY recovered but increased the purity. Using 0.3 M potassium sulphate, we recovered approximately 63.7% of the serum Ig as almost pure IgY.

Sol → gel transition with rings in a finite polycondensing system in solution

We report a theoretical formulation for the mean cluster size distribution in a finite polycondensing system. Expressions for the mean number of n-mers with j bonds ( nj) are developed. Numerical calculations show that while the non-cyclic molecules make the dominant contribution to the small clusters, the large clusters are dominated by cyclic structures. The number of particles in ringless chains, n n,n-1, decays monotonically with n at all extents of reaction, but n n becomes bimodal near the gel point. We also find that the solvent plays an important role in the cluster size distribution.

The Influence of Bilayer Composition on the Gel to Liquid Crystalline Transition

We report molecular dynamics simulations of bilayers using a united atom model with explicit solvent molecules. The bilayer consists of the single tail cationic surfactant behenyl trimethyl ammonium chloride (BTMAC) with stearyl alcohol (SA) as the cosurfactant. We study the gel to liquid crystalline transitions in the bilayer by varying the amount of water at fixed BTMAC to SA ratio as well as by varying the BTMAC to SA ratio at fixed water content. The bilayer is found to exist in the tilted, Lβ′ phase at low temperatures, and for the compositions investigated in this study, the Lβ′ to Lα melting transition occurred in the temperature range 330−338 K. For the highest BTMAC to SA composition (2:3 molar ratio), a diffuse headgroup−water interface is observed at lower temperatures, and an increase in the d-spacing occurs prior to the melting transition. This pretransition swelling is accompanied by a sharpening in the water density variation across the headgroup region of the bilayer. Signatures of this swelling effect which can be observed in the alkane density distributions, area per headgroup, and membrane thickness are attributed to the hydrophobic effect. At a fixed bilayer composition, the transition temperature (>338 K) from the Lβ′ to Lα transition obtained for the high water content bilayer (80 wt %) is similar to that obtained with low water content (54.3 wt %), confirming that the melting transition at these water contents is dominated by chain melting.

Gel growth and dielectric studies of K. Rb and Cs perchlorates

Single crystals of K, Rb and Cs perchlorates have been grown by the counter diffusion of the respective ions and CIO4 through the gel medium. Studies on nucleation, growth kinetics, morphological aspects and purity are discussed in this paper. The dielectric constant, ~b, as well as loss measured along the longest axis, exhibits an anomaly at the transition temperature, Tt, in all the three crystals. It is found that the peak values of Tt are approximately 800, 100 and 53 in K, Rb and Cs perchlorates, respectively. The dielectric anomaly and the large value of c b in the cubic phase are discussed in terms of the degree of disorder of the CIO~ group and the possible contribution from defects.

Cu2+ inhibition of gel secretion in the xylem and its potential implications for water uptake of cut Acacia holosericea stems

Maintaining a high rate of water uptake is crucial for maximum longevity of cut stems. Physiological gel/tylosis formation decreases water transport efficiency in the xylem. The primary mechanism of action for post-harvest Cu2+ treatments in improving cut flower and foliage longevity has been elusive. The effect of Cu2+ on wound-induced xylem vessel occlusion was investigated for Acacia holosericea A. Cunn. ex G. Don. Experiments were conducted using a Cu2+ pulse (5 h, 2.2 mM) and a Cu2+ vase solution (0.5 mM) vs a deionized water (DIW) control. Development of xylem blockage in the stem-end region 10 mm proximal to the wounded stem surface was examined over 21 days by light and transmission electron microscopy. Xylem vessels of stems stood into DIW were occluded with gels secreted into vessel lumens via pits from surrounding axial parenchyma cells. Gel secretion was initiated within 1-2 days post-wounding and gels were detected in the xylem from day 3. In contrast, Cu2+ treatments disrupted the surrounding parenchyma cells, thereby inhibiting gel secretion and maintaining the vessel lumens devoid of occlusions. The Cu2+ treatments significantly improved water uptake by the cut stems as compared to the control. © 2013 Scandinavian Plant Physiology Society.

Separation of sulfur-containing components of transfer ribonucleic acid on Bio-Gel P-2 and Sephadex G-10 columns

S-Labeled nucleosides of E. coli tRNA and some of the derivatives of thionucleosides were separated on Bio-Gel P-2 and Sephadex G-10 columns employing buffers of low salt concentration and high pH.

Hybrid Sol-Gel Combustion Synthesis of Nanoporous Anatase

Nanoporous anatase with a thin interconnected filmlike morphology has been synthesized in a single step by coupling a nonhydrolytic condensation reaction of a Ti precursor with a hybrid sol-gel combustion reaction. The method combines the advantages of a conventional sol-gel method for the formation of porous structures with the high crystallinity of the products obtained by combustion methods to yield highly crystalline, phase-pure nanoporous anatase. The generation of pores is initiated by the formation of reverse micelles in a polymeric polycondensation product, which expand during heating, leading to larger pores. A reaction scheme involving a complex formation and nonhydrolytic polycondensation reaction with ester elimination leads to the formation of ail extended Ti-O-Ti network. The effect of process parameters, such as temperature and relative ratio of cosurfactants, on phase formation has been studied. The possibility of band gap engineering by controlled doping during synthesis and the possibility of attachment of molecular/nanoparticle sensitizers provide opportunities for easy preparation of photoanodes for solar cell applications.

Optical, dielectric and morphological studies of sol-gel derived nanocrystalline TiO2 films

Nanocrystalline TiO2 films have been synthesized on glass and silicon substrates by sol-gel technique. The films have been characterized with optical reflectance/transmittance in the wavelength range 300-1000nm and the optical constants (n, k) were estimated by using envelope technique as well as spectroscopic ellipsometry. Morphological studies have been carried Out using atomic force microscope (AFM). Metal-Oxide-Silicon (MOS) capacitor was fabricated using conducting coating on TiO2 film deposited on silicon. The C-V measurements show that the film annealed at 300 degrees C has a dielectric constant of 19.80. The high percentage of transmittance, low surface roughness and high dielectric constant suggests that it can be used as an efficient anti-reflection coating on silicon and other optical coating applications and also as a MOS capacitor.

Sol-Gel Template Synthesis, Structural Characterization and Growth Mechanism of Barium Zirconate Nanotubes

In this paper, we report the synthesis of barium zirconate, BaZrO3, (BZ) nanotubes fabricated by the modified sol-gel method within the nanochannels of anodic aluminum oxide (AAO) templates. The morphology, structure, and composition of as prepared nanotubes were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), selected-area electron diffraction ( SAED), high resolution TEM (HRTEM) and energy-dispersive X-ray spectroscopy (EDX). The results of XRD and SAED indicated that postannealed (at 650 degrees C for 1 h) BZ nanotubes (BZNTs) exhibited a polycrystalline cubic perovskite crystal structure. SEM and TEM analysis revealed that BZNTs possessed a uniform length and diameter (similar to 200 nm) and the thickness of the wall of the BZNTs was about 20 nm. Y-junctions, multiple branching and typical T-junctions were also observed in some BZNTs. EDX analysis demonstrated that stoichiometric BaZrO3 was formed. HRTEM image confirmed that the obtained BZNTs were composed of nanoparticles in the range of 5-10 nm. The possible formation mechanism of BZNTs was discussed.

Fabrication and Phase Transformation in Crystalline Nanoparticles of PbZrO3 Derived By Sol-Gel

In this research fabrication of crystalline PbZrO3 (PZ) nanoparticles and their phase transformation behavior is investigated. A novel sol-gel method was used for the synthesis of air-stable and precipitate-free diol-based sol of PZ, which was dried at 150 degrees C and then calcined at 300-700 degrees C for 1 h. The morphology, crystallinity and phase formation of as synthesized nanoparticles were studied by the selected-area electron diffraction (SAED), X-ray diffraction (XRD), thermal gravimetric analysis/differential scanning calorimetry (TGA-DSC), and high resolution transmission electron microscope (HRTEM). The XRD, SAED, and TGA-DSC analyses confirmed the tetragonal lead rich zirconia phase (t-Z phase) and monoclinic zirconia phase (m-Z phase) as the intermediate phases during the calcinations process followed by crystallization of single orthorhombic PZ phase at about 700 degrees C. The average PZ particle size was observed about 20 nm as confirmed by TEM study. Energy-dispersive X-ray spectroscopy (EDX) analysis demonstrated that stoichiometric PbZrO3 was formed.

Nd2O3 : Eu3+ nanocrystalline phosphor - a new potential thermoluminescing material for dosimetry

Nanoparticles of trivalent Eu3+-doped Nd2O3 phosphors have been prepared using a low-temperature solution combustion method with metal nitrate as precursor and oxalyldihydrazide as a fuel at a fairly low temperature (<500 degrees C) and in a very short time (<5 min). A powder X-ray diffraction pattern reveals that cubic Nd2O3 : Eu3+ crystallites are directly obtained without the requirement of further calcinations. The crystallite size, evaluated from Scherer's formula, was found to be in the range of 20-30 nm. The microstructure and morphology were studied by scanning electron microscopy, which showed the phosphor to be foamy and fluffy in nature. Thermoluminescence characteristics of the Nd2O3 : Eu3+ have been studied using gamma irradiation. These demonstrate that the phosphor is suitable for use as a dosimeter.

Dielectric anomaly in Li-doped zinc oxide thin films grown by sol-gel route

Sol-gel route was employed to grow polycrystalline thin films of Li-doped ZnO thin films (Zn1-xLixO, x=0.15). Polycrystalline films were obtained at a growth temperature of 400-500 degrees C. Ferroelectricity in Zn0.85Li0.15O was verified by examining the temperature variation of the real and imaginary parts of dielectric constant, and from the C-V measurements. The phase transition temperature was found to be 330 K. The room-temperature dielectric constant and dissipation factor were 15.5 and 0.09 respectively, at a frequency of 100 kHz. The films exhibited well-defined hysteresis loop, and the values of spontaneous polarization (P-s) and coercive field were 0.15 mu C/cm(2) and 20 kV/cm, respectively, confirming the presence of ferroelectricity.

Effect of Polymer Grafting on the Bilayer Gel to Liquid-Crystalline Transition

Grafted polymers oil the surface of lipid membranes have potential applications in liposome-based drug delivery and Supported membrane systems. The effect of polymer grafting on the phase behavior of bilayers made up of single-tail lipids is investigated using dissipative particle dynamics. The bilayer is maintained in a tensionless state using a barostat. Simulations are carried Out by varying the grafting fraction, G(f), defined as the ratio of the number of polymer molecules to the number of lipid molecules, and the length of the lipid tails. At low G(f), the bilayer shows I sharp transition from the gel (L-beta) to the liquid-crystalline (L-alpha) phase. This main melting transition temperature is lowered as G(f) is increased, and above a critical value of G(f), the interdigitated L-beta I phase is observed prior to the main transition. The temperature range over which the intermediate phases are observed is a function of the lipid tail length and G(f). At higher grafting fractions, the presence of the L-beta I, phase is attributed to the increase in the area per head group due to the lateral pressure exerted by the polymer brush. The areal expansion and decrease in the melting temperatures as a function of G(f) were found to follow the scalings predicted by the self-consistent mean field theories for grafted polymer membranes. Our study shows that the grafted polymer density can be used to effectively control the temperature range and occurrence of a given bilayer phase.

Influence of surfactant and annealing temperature on optical properties of sol-gel derived nano-crystalline TiO2 thin films

Titanium dioxide thin films have been synthesized by sol-gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 degrees C. The influence of surfactant and annealing temperature on optical properties of TiO2 thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO2 films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO2 films was estimated by Tauc's method at different annealing temperature. (C) 2010 Elsevier B.V. All rights reserved.