Procedia Chemistry最新文献

Leptospirosis is an endemic zoonotic disease in tropical countries. However, detection using the microagglutination test (MAT) as a gold standard is difficult to perform in Indonesia. Therefore, recombinant LipL32 protein (rLipL32) has been studied as an antigen for an ELISA test to detect Leptospirosis. We produced rLipL32 using the pRSET-C vector and expressed it in E. coli BL21 (DE3) competent cells. Under native conditions, we purified 2 mg rLipL32 protein from 500 ml culture. Analysis using western blotting and ELISA showed that serum from the bovine positive MAT serovar Hardjo could recognize pure rLipL32 protein. This result confirms an earlier study that indicates that rLipL32 protein is a good antigen for Leptospirosis detection. The diagnostic assay using rLipL32 is safe because it does not use infectious bacteria as an antigen and because it is easy to perform in every diagnostic laboratory in Indonesia. However, further study is still required for field validation of the rLipL32 assay.

This work aimed to search optimal values for the properties of hydroxyapatite coated pure magnesium produced by cold spray deposition. Using fractional factorial design (2^k-1), standoff distance, surface roughness and substrate heating temperature during cold spraying were selected as significant factors while number of sprays as insignificant factor. The responses chosen are coating thickness, hardness and elastic modulus of the coating. The analysis of the contour plots for thickness revealed that high thickness (>40 μm) was obtained when standoff distance is at 20-25 mm, surface roughness at 240-700 grit and substrate heating temperature at 350-550 °C. High nanohardness (>400 MPa) obtained when standoff distance is at 20-35 mm, surface roughness at 240-900grit and substrate heating temperature at 350-550 °C. High elastic modulus (>40 GPa) was obtained at 20-30 mm for standoff distance, 240-800 grit for surface roughness and 350-550 °C for substrate heating temperature. The contour plot of coating thickness, nanohardness and elastic modulus were overlaid to find the feasible region.

ZnOmaterial has unique electrical and optical properties that many important applications, including as an anti-reflection coating in dye sensitized solar cells. Flat anti-reflective coatings (ARC) made of ZnO on top to improve the optical properties of the coating. In this study, ZnO nanoparticle were coated with TiO₂ nanolayers by a simple wet chemical route. TiO₂ nanorods coated ZnO nanoparticle was synthesized by two step i.e. (1) base hydrolysis and polymerization of TiO₂ (2) ZnO nanoparticle were coated with a TiO₂ layer. The TiO₂ coated ZnO prepared was characterized by X-ray diffraction (XRD), Reflectance spectroscopy, SEM and TEM. ZnO annealed at a temperature of 400^oC have the greatest crystal size than annealedat a temperature of 500 °C and 600 °C. While, the Reflectance (%R)properties shows that the higher annealing temperature of ZnO preparations, the higher of %R value of ZnO thin layer. The ZnO prepared by annealed at 400^oCgain a good performance of the lowest reflectance value. The difference properties are due to differences of light scattering resulting from the crystal size effect. The crystals size that have a good performance as an anti-reflection is around 20 nm, result study of ZnOannealed at 400 °C. TEM nanograph shows that the synthesized ZnO have spherical morphology. The optimum performance ofDSSCs was conducted using the photoanode ZnO-coated TiO₂at present 10%APTMS as surface modifier anchor dye group. Bythe addition of ARC we have been capable improve cell performance so that cells achieve an efficiency of 1.13%.

Hydrogels are widely used as biomaterials in biomedicalfields such as in drug delivery systems, cell-based therapies, wound dressing, implant materials for soft tissue and anti-adhesion materials due to its unique characteristics. The aim of this project is to fabricate UV-crosslinked hydrogel film with the tailored chemical and physical properties that can be utilized as scaffold. Three series of UV-crosslinked poly(ethylene glycol) diacrylate/ poly(dimethylsiloxane) dimethacrylate (PEGDA/PDMS-MA) hydrogels were fabricatedby exposing the precursor solutions under UV chamber that provides a spectral range of UVA at average intensity of 40W/cm². Equilibrium swelling ratio (ESR) was found higher in the UV-crosslinked hydrogels that exposed to the UV at shorter time, with lower loading of PDMS-MA, and higher molecular weight of PEGDA. The concentration of photoinitiator was found to haveinsignificant effect on ESR%. Whereas, dynamic contact angle (DCA) measurement revealed that the hydrophilicity was higher forPEGDA UV-crosslinked hydrogels with higher ratio. Besides, dynamic mechanical analysis (DMA)showed that the incorporation of PDMS-MA reduced the average value of compressive modulus of the UV-crosslinked hydrogels. Differential scanning calorimetry (DSC) analysis showed that lower glass transition temperature (T_g) of PDMS-MA could be related to the reduction of stiffness in UV-crosslinked hydrogels. It was found that the fabricated UV-crosslinked hydrogels were suited to cartilage tissue engineering application due to similar properties to the cartilage tissue.

An amperometric nitrate biosensor was successfully constructed by the electroimmobilization of the enzyme nitrate reductase from Aspergillus niger with and without β-NADH, a co-factor, into conducting polypyrrole films on screen printed carbon electrode (SPCE). The best performance was registered by nitrate biosensor developed without the β-NADH electroimmobolize with nitrate reducatse on the SPCE. The formation of the optimum NaR-PPy composite on the SPCE was achieved with an applied potential of 0.9 Vs^-1 for 900s. The optimum amperometric response for nitrate was obtained in 0.1M potassium phosphate buffer, pH 7.5 with an applied potential of -0.1 Vs^-1 and 2mM β-NADH. Sensitivity of the nitrate biosensor was found to be in a linear range of 0.01-0.25mM with a regression coefficient of 0.97 and a relative standard deviation (RSD) of 6.6% (n=5).

This paper presents the surface treatment of multiwalled carbon nanotube (MWCNT)/muscovite (MUS) hybrid nanomaterial. The hybrid compound was synthesized by chemical vapor deposition (CVD) using methane as the carbon precursor. Morphological characterization of treatment and pristine MWCNT-MUS hybrid was conducted using Field Emission Scanning Electron Microscope (FESEM) and X–ray diffraction (XRD). The surface treatment of MWCNT/MUS hybrid nanomaterial was successfully carried out which the basal spacing of (001) plane d₍₀₀₁₎ of MCNT/MUS was enlarged from 21.00 Å to 27.20 Å after first stage after first stage and was further enlarged to 29.28 Å after second stage of CTAB treatment. This MCNT-MUS hybrid filler was incorporated into epoxy resin at different filler loadings (0.5, 1.0, and 1.5 wt %). Thermal properties of the treated Epoxy/MWCNT-MUS was determined to have lower properties compared to pristine Epoxy/MWCNT-MUS.

A nitrate ion selective electrode (nitrate-ISE) based on pyrrole modification on a common pencil lead was proposed. The lab-made nitrate-ISE was easily constructed by pyrrole polymerization with nitrate ion as the dopant using cyclic voltammetry. The fabricated nitrate-ISE was then coupled with flow injection analysis (FIA) for an automatic system. The flow potentiometry provided working range of 1x10^-4 to 4x10^-3 mol L^-1 of nitrate and allowed sample throughput up to 50 samples h^-1. Linear regression analysis showed good agreement (r²=0.9961) with Nernstian response. This system was applied to determine nitrate-nitrogen (nitrate-N) in fertilizer samples.

Fast with high-performance CuO nanorod arrays IR photodetector was fabricated using CuO nanorod arrays/AAO assembly. The IR photodetector based on MSM with Al contact electrodes and its optoelectronic properties were examined. The CuO nanorod arrays used in the experiment were synthesized by DC electrodeposition method into Si-based/AAO template. The electrical performance and photoelectric response performance were studied, and the results showed that IR photodetector exhibited a high sensitivity to 808 nm infrared diode laser source. Both the response and recovery time were found to be fast; 0.19 and 0.15 s, respectively, which are shorter time compared to other IR photodetectors reported in the literature.