Darapond Triampo

ZnO nanoparticles and nanowire array hybrid photoanodes for dye-sensitized solar cells

ZnO nanoparticle-nanowire (NP-NW) array hybrid photoanodes for dye-sensitized solar cell (DSC) with NW arrays to serve as a direct pathway for fast electron transport and NPs dispersed between NWs to offer a high specific surface area for sufficient dye adsorption has been fabricated and investigated to improve the power conversion efficiency (PCE). The overall PCE of the ZnO hybrid photoanode DSC with the N3-sensitized has reached ∼4.2%, much higher than both ∼1.58% of ZnO NW DSC and ∼1.31% of ZnO NP DSC, prepared and tested under otherwise identical conditions.

Leptospirosis: current situation and trends of specific laboratory tests

Leptospirosis is re-emerging as a worldwide zoonosis and is caused by bacteria of the genus Leptospira. Human leptospirosis is associated with high temperature and humidity. Laboratory tests are indispensible for the early diagnosis and proper disease management. The demand for suitable leptospirosis point-of-care diagnostic tests grows with the awareness and number of incidences. Confirmation is achieved by the microscopic agglutination test, bacterial cultivation, PCR or histopathologic methods. However, high costs, poor standardization and/or elaborate sample preparation prevent routine use at the point of care. Cost-efficient, but insensitive serological methods dominate the diagnostic landscape and, likewise, urgently need improvement toward greater compliance with some of the point-of-care criteria. Combined application of antigen and antibody detection methods increases accuracy, but also new development or transfer of diagnostic technologies should be considered useful. Nano- and microparticle technology may play a key role in improving future antigen detection methods.

Encapsulation of TiO 2 nanoparticles into single-walled carbon nanotubes

Nanostructures such as carbon nanotubes and titanium dioxide (TiO2) offer the means to create novel nanoscale devices and technologies. The question as to whether or not TiO2-nanoparticle (TiO2-NP) can be encapsulated in a single-walled carbon nanotube (SWNT) depends on the physical and chemical interactions between the TiO2-NP and the SWNT. Motivated by nanoscale encapsulation research and nanoscale delivery systems, we present a simple but useful model to study the system comprised of an SWNT encapsulated with TiO2-NP under various conditions. Using the well-known Lennard-Jones (6-12) potential for both cylindrical- and spherical-shaped TiO2- NP, analytical expressions are obtained for calculating the potential energy, the encapsulating energy and the force distribution and other quantities. In particular, the suction force experienced by an SWNT located near an open end of a

Development of a magnetic bead fluorescence microscopy immunoassay to detect and quantify Leptospira in environmental water samples

Climate change, world population growth, and poverty have led to an increase in the incidence of leptospirosis. Leptospirosis is caused by pathogenic spirochaete bacteria that belong to the genus Leptospira. The bacteria are maintained in the renal tubules of the reservoir hosts (typically a rodent), then shed into the environment via the urine. Water is key for environmental survival and transmission, as leptospires can survive for several weeks in a moist environment. Therefore, environmental epidemiological studies are needed to study the contamination of environmental water sources. However, few such studies have been performed using cultivation of the isolates and PCR assays. But, leptospira cultivation can be easily contaminated by other organisms and takes usually several weeks. Moreover, PCR is a complex and costly analysis for the underdeveloped countries that have the highest incidence of leptospirosis. In this study, we describe two modifications of a fluorescence microscopy assay based on immuno-magnetic separation (IMS) to detect leptospires in environmental water samples that mainly differ in fluorescent dye staining. The first type uses acridine orange fluorescent dye staining combined with multiplexed IMS for sample screening. The detection limit ranged from 10(2) to 10(3) organisms per mL and largely depended on the capture efficiency (CE) of the immuno-magnetic particles. The second type uses serogroup-specific immuno-particles and direct fluorescence antibody staining (DFA) to detect leptospires; the detection limit of this second assay was approximately 10(1) cells per mL. Both assay types were applied to natural and experimentally infected water samples, which were also analysed with DFM and real-time PCR. Our data show that the fluorescent microscopy immunoassay successfully identified experimental leptospire contamination and was as sensitive as PCR. This modified immune-fluorescence assay may therefore enable epidemiological studies of leptospirosis.

Leptospirosis research: fast, easy and reliable enumeration of mobile leptospires

Leptospirosis caused by Leptospira interrogans is the most widespread zoonosis and a major public health problem worldwide. Based on light-scattering and absorption, quantification of leptospires using UV-VIS spectroscopy was used as an indirect counting technique by measuring the optical density and comparing this to automated direct counting using a counting chamber in combination with imaging and analyzing software. Two serovars, Bangkok and Copenhagenii, from log-phase growth were used for the establishment of standard curves. They were found to be linear and slightly different in gradient for each serovar. The ease, rapidity, and reliability of these two adapted and optimized counting techniques may provide a useful alternative enumeration technique for leptospirosis research.

Effects of static magnetic field on growth of leptospire, Leptospira interrogans serovar canicola: immunoreactivity and cell division.

The effects of the exposure of the bacterium, Leptospira interrogans serovar canicola to a constant magnetic field with magnetic flux density from a permanent ferrite magnet=140+/-5 mT were studied. Changes in Leptospira cells after their exposure to the field were determined on the basis of changes in their growth behavior and agglutination immunoreactivity with a homologous antiserum using dark-field microscopy together with visual imaging. The data showed that the exposed Leptospira cells have lower densities and lower agglutination immunoreactivity than the unexposed control group. Interestingly, some of the exposed Leptospira cells showed abnormal morphologies such as large lengths. We discussed some of the possible reasons for these observations.

Development of a diagnostic and remedial learning system based on an enhanced concept–effect model

With the rapid advances in computer technology during recent years, researchers have demonstrated the pivotal influences of computer-assisted diagnostic systems on student learning performance improvement. This research aims to develop a Diagnostic and Remedial Learning System (DRLS) for an algebra course in a Thai lower secondary school context based on an enhanced learning diagnosis model which employs a novel technique to preset weight of association concepts for each test item and the learning preference style of individual students to advise the students how to improve their learning performance. To evaluate the effectiveness of this innovative approach, an experiment has been conducted on an algebra course in a Thai secondary school. Pre- and post-test, questionnaire and interview data have revealed that the suggestions provided by the system could help the students improve their learning performance.

Stochastic cellular automata model and Monte Carlo simulations of CD4+ T cell dynamics with a proposed alternative leukapheresis treatment for HIV/AIDS

Acquired Immunodeficiency Syndrome (AIDS) is responsible for millions of deaths worldwide. To date, many drug treatment regimens have been applied to AIDS patients but none has resulted in a successful cure. This is mainly due to the fact that free HIV particles are frequently in mutation, and infected CD4(+) T cells normally reside in the lymphoid tissue where they cannot (so far) be eradicated. We present a stochastic cellular automaton (CA) model to computationally study what could be an alternative treatment, namely Leukapheresis (LCAP), to remove HIV infected leukocytes in the lymphoid tissue. We base our investigations on Monte Carlo computer simulations. Our major objective is to investigate how the number of infected CD4(+) T cells changes in response to LCAP during the short-time (weeks) and long-time (years) scales of HIV/AIDS progression in an infected individual. To achieve our goal, we analyze the time evolution of the CD4(+) T cell population in the lymphoid tissue (i.e., the lymph node) for HIV dynamics in treatment situations with various starting times and frequencies and under a no treatment condition. Our findings suggest that the effectiveness of the treatment depends mainly on the treatment starting time and the frequency of the LCAP. Other factors (e.g., the removal proportion, the treatment duration, and the state of removed cells) that likely influence disease progression are subjects for further investigation.

AMYLOSE/AMYLOPECTIN SIMPLE DETERMINATION IN ACID HYDROLYZED TAPIOCA STARCH

ABSTRACT Analysis of the shift of wavelength maximum using a rapid colorimetric method was used to determine the ratio of amylose:amylopectin (Am:Ap) in acid-hydrolyzed tapioca starch. The absorbance maximum of 600 nm (Am:Ap of tapioca starch ≈22:78) moved to shorter wavelengths (590, 585, 570, 560, and 534 nm) as the decrease of the Am:Ap ratio due to hydrolysis of shorter chains that are not be able to form a complex with iodine. The amount of amylopectin itself may be unaltered or slightly decreased but the decrease in amylose caused a decrease in Am:Ap ratio.Keywords: amylose, amylopectin, acid hydrolysis, colorimetricemail: scdar@mahidol.ac.th INTRODUCTION Starch is the major carbohydrate reserve of plant tubers and seed endosperm. 1 The largest source of starch is maize, wheat, potato, tapioca, and rice. Starch is widely used as thickener, water binder, emulsion stabilizer, and gelling agent. Each starch granule typically contains amylopectin, a linear chain of (1→4)-α-D-glucose residues connected through branched (1→6)-α-linkages, and a much larger number of the smaller amylose, α(1→4) linearly linked D-glucopyranosyl residues.Amylose is a hydrocolloid. Its extended conformation causes the high viscosity of water-soluble starch which varies relatively little with temperature. The extended loosely helical chains possess a relatively hydrophobic inner surface that is not able to hold water. Amylose forms useful gels and films. Its association and crystallization (retrogradation) on cooling and storage decrease storage stability, causing shrinkage and the release of water (syneresis). Increasing amylose concentration decreases gel stickiness, but increases gel firmness. Amylopectin interferes with the interaction between amylose chains (and retrogradation) and its solution can lead to an initial loss in viscosity and followed by a more slimy consistency.The simplest and most common starch modification is by acid hydrolysis, which is widely used in food, paper, textile, and pharmaceutical industries.

Chemical force mapping of phosphate and carbon on acid-modified tapioca starch surface

Surface chemical microstructure of hydrochloric acid hydrolyzed tapioca starch producing different amylose:amylopectin (Am:Ap) ratios were studied with scanning chemical force microscopy (CFM). The chemical force probes were functionalized of two types with -OH (phosphate specific) and -CH3 (carbon specific). Lateral force trace-minus-retrace (TMR) images from -OH and -CH3 probes revealed changes in the phosphate domains and the carbon backbone for the varying acid hydrolyzed tapioca starch compared to that of the native tapioca starch. Scanning electron micrographs (SEM) showed different degree of the granule surface disruption before and after hydrolysis. The exterior structures of the acid hydrolyzed starch granules were chemically investigated with CFM to study the relationships of the surface molecular structures and the Am:Ap ratios.