Colorimetric determination of ascorbic acid based on carbon quantum dots as peroxidase mimetic enzyme

Carbon quantum dots (CQDs) were synthesized from litchi peel, exhibiting a peroxidase-like activity and enabling the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in association with H2O2 to generate blue oxidized TMB (ox-TMB) with a strong absorption peak at 652 nm.

Extraction Cellulose From Rice Husk

Cellulose from rice husk has been successfully synthesized. Rice husk is an abundant agricultural waste and has a high cellulose content. Bioconversion of rice husk into cellulose begins with the stages of delignification and bleaching. The resulting cellulose was characterized using FTIR and XRD. The IR spectra show a strong absorption peak at 3444.87 cm− 1 which is associated with stretching vibrations O − H (hydrogen bonds between molecules), absorption peaks at 1033.85 cm− 1 are identified as stretching C − O − C which is β bond −1,4 glycosidic from cellulose. XRD shows the particle size of cellulose which is 3.44 nm and has crystallinity of 58.73%. These results indicate that cellulose from rice husk has good characteristics. Keywords: Rice Husk, Cellulose, FTIR, XRD

Highly Tm Doped Silica Optical Preform by MCVD - Chelate Vapor Delivery (Soot-Dopant Stepwise Technique)

This paper presents the progress in the fabrication of highly doped thulium silica fiber. As much as 5.3 wt. % Tm alongside 7.1 wt. % Al (co-dopant) were incorporated into silica preform. The preform was fabricated using the Modified Chemical Vapor Deposition (MCVD)-chelate vapor delivery with soot-dopant stepwise technique. The preform was analyzed for several key properties such as refractive index variation along deposition length, dopants distribution profiles and UV-Vis absorption. The results showed a homogeneous dopants distribution with 4% RSD in the longitudinal refractive index along a 40 cm preform length. The UV-Vis absorption spectrum exhibited a strong absorption peak at 790 nm attributed to Tm 3H4 energy manifold.

Synthesis of Platinum nanoparticles by Gamma Radiolysis

The synthesis of Platinum (Pt) nanoparticles by gamma irradiation is presented. The 0.1 M Pt solution of different concentration was prepared from K2PtCl4. The platinum aqueous solutions were irradiated by gamma radiation at a dose of 70, 90 and 120 kGy. The findings show the effect of irradiation on PtII solutions with different concentrations. The big black particles that are fairly agglomerated when the concentration was above 0.0050 M were observed. The UV-Vis spectrum of Pt of different concentrations shows a strong absorption peak at the wavelength 261 nm after irradiation, which indicates the presence of platinum nanoparticles. Furthermore, FTIR, XRD and HRTEM images also confirmed the presence of the nanoparticles produced by Radiolysis. The size of the Pt nanoparticles was found to be 7.39 nm.

Preparation and Research of Polymolybdate/Polymer Composite Membrane by Electrospinning and its Photo-Catalytic Property

Composite cellulosic membrane of PMMA and phosphomolybdic acid was prepared by electrospinning. During the progress, the factor of electrospinning and the optimum parameters was found out within the orthogonal combination experiment program. Then the morphology of the composite cellulosic membrane was observed by polarizing microscopy. To resolve PMMA, DMF and anhydrous alcohol were used. When their ratios were 1:1, the diameter of the fibre was the most homogeneous. During the electrospinning, the concentration of PMMA was the most important factor. When the concentrations were less then 10%, there were hardly fibres on the foil. The diameter of the fibre ranged from 0.5 to 1.2 μm along with the increment of the concentration of PMMA. The addition of phosphomolybdic acid made the diameter of the fibre decrease. IR-spectra showed that phosphomolybdic acid kept its Keggin structure, and it interacted with PMMA through hydrogen bond. The composite cellulosic membrane changed its color when imposed in bright space. UV spectra represented that the composite cellulosic membrane had a strong absorption peak at 700nm.

Preparation of Green Nanosilver by Ascorbic Acid and its Spectral Properties

In the presence of stabilizer of citrate and room temperature, stable green nanosilver sol was prepared by reduction of AgNO3by ascorbic acid. It was characterized by UV-visible spectroscopy, resonance Rayleigh scattering (RRS) spectroscopy, laser scattering and transmission electron microscopy. Results showed that the nanosilver sol exhibited a RRS peak at 496 nm, a strong absorption peak at 414 nm and the particle size is 12 nm.

Microwave-Assisted Extraction of Chlorophyll from Filter Mud of Sugercane Mill and Component Analysis

Microwave-assisted extraction (MAE) was used to extract chlorophylls from filter mud. Ethanol was used as the solvent. The optimal conditions for the MAE of chlorophylls were concluded from the study as the irradiation time, 50 s, the ratio of liquid to solid, 8:1 (mL/g), the extraction temperature, 40 °C, and the extraction time, 60 min. Compared with conventional extraction, the MAE of chlorophylls from the filter mud was more effective. The extraction time for MAE was 60 min with 0.277 mg/g chlorophyll yield, while conventional extraction needed 240 min with only about 0.259 mg/g chlorophyll yield. The Ultraviolet Absorption Spectra of the extracted chlorophylls showed that there was a strong absorption peak at about 663 nm. C=N, Mg-N and C-N was not seen existed from the infrared spectroscopy probably because that the mixed extracts were not purified and the chlorophyll content was less.

Preparation and Characterization of Skin-Colored N-Doped ZnO Nanocrystals

In this paper, we report a simple two-step approach (microwave-calcinating) to prepare skin-colored N-doped ZnO nanocrystals. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and UV-visible absorption were used to characterize the as-synthesized products. The FESEM results reveal the products mainly take on the morphology of porous flake constructed by 20 nm nanoparticles. UV-Vis spectrum shows a strong absorption peak located at 384nm.

Band-To-Band Transitions in Poly (Phenyl Methyl Silane)

ABSTRACTWe have measured the quantum efficiency for carrier generation as a function of photon energy and the electroabsorption spectrum in poly (phenyl methyl silane). The experimental data are consistent with a band gap of about 4.6 eV. A strong absorption peak which is observed at 3.7 eV is shown to be an exciton band.