A wideband sensitive holographic photopolymer

A novel wideband sensitive dry holographic photopolymer sensitized by rose bengal (RB) and methylene blue (MB) is fabricated, the holographic storage characteristics of which are investigated under different exposure wavelengths. The result shows that the sensitive spectral band exceeds 200 nm in visible light range, the maximum diffraction efficiency under different exposure wavelengths is more than 40% and decreases with the decrease of exposure wavelength, the exposure sensitivity is not change with the exposure wavelength. This photopolymer is appropriate for wavelength multiplexing or multi-wavelength recording in digital holographic storage.

Riboflavin sensitized photopolymer materials for holographic storage

Riboflavin is employed as the photosensitizer of a novel photopolyrner material for holographic recording, This material has a broad absorption spectrum range (More than 200nm) due to the addition of this dye. The experimental results show that our material has high diffraction efficiency and large refractive index modulation. The maximum diffraction efficiency of the photopolymer is about 56%. The digital data pages are stored in this medium and the reconstructed data page has a good fidelity, with the bit-error-ratio of about 1.8 X 10(-4). it is found that the photopolymer material is suitable for high-density volume holographic digital storage.

活性炭纤维(ACF)吸附法处理河流突发污染事故模拟研究

环境突发污染事故给人民生活、经济发展和生态环境造成重大影响，研究污染物泄漏造成河流突发污染事故的应急处理方法十分必要。本论文选取苯酚、苯胺和亚甲基蓝等典型污染物为实验对象，采用吸附容量大、密度与水接近的活性炭纤维(ACF)为吸附剂。在自制的河流模型中，研究了ACF以苯酚、苯胺和亚甲基蓝为典型污染物的吸附过程，考察了吸附剂投加量、污染物浓度、吸附剂比表面积、吸附剂投加方式、水流速度与水质等对吸附速率与吸附效果的影响。实验结果表明，ACF能以较快的速率吸附苯酚、苯胺和亚甲基蓝，吸附率都在95％以上； ACF投加量是影响吸附速率最重要的因素，当一次性投加ACF质量之比为 1:2:4时，吸附速率常数之比近似为1:2:4；污染物浓度对吸附速率的影响显著，浓度较低时吸附速率较高。苯酚初始浓度为7mg·L-1时，经过86分钟的吸附，处理后的浓度可以达到地表水Ⅴ类水中挥发酚的限值要求(0.1mg·L-1)；在吸附11分钟左右追加适量的ACF，能够明显提高吸附速率；河水流速和河流中的天然有机物、浊度、河水硬度对ACF吸附都不产生显著影响，这说明ACF作为河流突发污染事故应急处理的吸附剂，有广泛的适应性。在实际河水中，ACF对苯酚的吸附过程与在模拟河水中相似，吸附效果显著。实验结果还表明，ACF对苯酚的吸附是放热反应，符合Freundlich模型和Langmuir模型。事故应急处理后，应该及时将吸附了污染物的ACF打捞上来，有利于进行后续处理。 Emergency environmental pollution accidents pose significant impacts on our living, economic development and ecological environment. The study on the approach of emergency control for the contingency caused by leakage of pollutants in rivers is very necessary. In the experiment, phenol, aniline and methylene blue were selected as representative pollutant and activated carbon fiber (ACF) was selected as adsorbent, which has strong adsorption capacity and similar density to water. In the self-made river model, the effects of ACF dosage, pollutant concentration, ACF surface area, ACF adding ways, water flow rate and water quality on adsorption courses were investigated. The experimental results showed that ACF could adsorb pollutant quickly and effectively. The ACF dosage was the most important factor that affected adsorption rate .When the ACF dosage rate was 1:2:4, the constants of adsorption rate was approximately 1:2:4. The effect of pollutant concentrations on the adsorption rate was notable. Faster adsorption rates were achieved at low pollutant concentrations. Phenol concentration reached the limits of volatile phenol in Category Ⅴ surface water (0.1 mg·L-1) after 86 minutes of adsorption with initial phenol concentration of 7 mg·L-1. After 11 minutes of adsorption, certain amount of ACF was added and the adsorption rate was improved significantly. River flow rate and water quality have little effect on the adsorption rate. The adsorption results obtained in actual river water were comparable with that in simulating river water. The results also showed that, ACF on the absorption of phenol is exothermic reaction, witch matched with the Freundlich model and the Langmuir model. After emergency treatment, the ACF absorbed pollutants should be promptly salvaged for follow-up treatment.

Activated carbons chemically modified by concentrated H2SO4 for the adsorption of the pollutants from wastewater and the dibenzothiophene from fuel oils

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150-270 degreesC. The modified AC was characterized by N-2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 degreesC greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m(2)/g to 745 m(2)/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon-oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 degreesC. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 degreesC has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.

Hydrothermal Synthesis and High Photocatalytic Activity of 3D Wurtzite ZnSe Hierarchical Nanostructures

Novel 3D wurtzite ZnSe hierarchical nanostructures have been synthesized by a mild hydrothermal treatment. The as-prepared flowerlike nanostructures efficiently catalyze the photodegradation of methylene blue and ethyl violet present in aqueous solutions under UV light irradiation, exhibiting higher photocatalytic activity than the commercially available photocatalysts P25 and ZnSe microspheres. We also demonstrate that flowerlike morphology is important for the excellent photocatalytic activity.

Self-assembly of lambda-DNA networks/Ag nanoparticles: Hybrid architecture and active-SERS substrate

In this article, highly rough and stable surface enhanced Raman scattering (SERS)-active substrates had been fabricated by a facile layer by-layer technique. Unique lambda-DNA networks and CTAB capped silver nanoparticles (AgNP) were alternatively self-assembled on the charged mica surface until a desirable number of bilayers were reached. The as-prepared hybrid architectures were characterized by UV-vis spectroscopy, tapping mode atomic force microscopy (AFM) and confocal Raman microscopy, respectively.

Type I collagen-templated assembly of silver nanoparticles and their application in surface-enhanced Raman scattering

Silver nanoparticles (Ag NPs) are one of the active substrates that are employed extensively in surface-enhanced Raman scattering (SERS), and aggregations of Ag NPs play an important role in enhancing the Raman signals. In this paper, we fabricated two kinds of SERS-active substrates utilizing the electrostatic adsorption and superior assembly properties of type I collagen. These were collagen-Ag NP aggregation films and nanoporous Ag films.

Facile Synthesis and Assemblies of Flowerlike SnS2 and In3+-Doped SnS2: Hierarchical Structures and Their Enhanced Photocatalytic Property

Novel flowerlike SnS2 and In3+-doped SnS2 hierarchical structures have been successfully synthesized by a simple hydrothermal route using biomolecular L-Cysteine-assisted methods. The L-cysteine plays an important role both as assistant and as sulfur source. Experiments with various parameters indicate that the pH values have a strong effect on the morphology of the assembly. Based on the experiments, a growth mechanical process was proposed. The synthetic samples were characterized by XRD, SEM, TEM (HRTEM), BET measurement, TGA, and XPS in detail.

Au nanoparticles grafted sandwich platform used amplified small molecule electrochemical aptasensor

We report a sensitively amplified electrochemical aptasensor using adenosine triphosphate (ATP) as a model. ATP is a multifunctional nucleotide thatis most important as a "molecular currency" of intracellular energy transfer. In the sensing process, duplexes consisting of partly complementary strand (PCS1), ATP aptamer (ABA) and another partly complementary strand (PCS2) were immobilized onto Au electrode through the 5'-HS on the PCS1. Meanwhile, PCS2 was grafted with the Au nanoparticles (AuNPs) to amplify the detection signals. In the absence of ATP, probe methylene blue (MB) bound to the DNA duplexes and also bound to guanine bases specifically to produce a strong differential pulse voltammetry (DPV) signal. But when ATP exists, the ABA-PCS2 or ABA-PCS1 part duplexes might be destroyed, which decreased the amount of MB on the electrode and led to obviously decreased DPV signal.

Real-time PCR microfluidic devices with concurrent electrochemical detection

Electrochemistry-based detection methods hold great potential towards development of hand-held nucleic-acid analyses instruments. In this work, we demonstrate the implementation of in situ electrochemical (EC) detection method in a microfluidic flow-through EC-qPCR (FTEC-qPCR) device, where both the amplification of the target nucleic-acid sequence and subsequent EC detection of the PCR amplicon are realized simultaneously at selected PCR cycles in the same device. The FTEC-qPCR device utilizes methylene blue (MB), an electroactive DNA intercalator, for electrochemical signal measurements in the presence of PCR reagent components. Our EC detection method is advantageous, when compared to other existing EC methods for PCR amplicon analysis, since FTEC-qPCR does not require probe-modified electrodes, or asymmetric PCR, or solid-phase PCR. Key technical issues related to surface passivation, electrochemical measurement, PCR inhibition by metal electrode, bubble-free PCR, were investigated. By controlling the concentration of MB and the exposure of PCR mixture to the bare metal electrode, we successfully demonstrated electrochemical measurement of MB in solution-phase, symmetric PCR by amplifying a fragment of lambda phage DNA.

Label-free electrochemical detection of DNA in blood serum via target-induced resolution of an electrode-bound DNA pseudoknot

We have demonstrated a fully covalent, signal-on E-DNA architecture based on the target-induced resolution of a DNA pseudokont. In the absence of target, the electrode-bound DNA probe adopts a pseudoknot conformation that segregates an attached methylene blue (MB) from the electrode. Upon target binding, the pseudoknot is resolved, leading to the formation of a single-stranded DNA element that supports electron transfer from the methylene blue to the electrode.

Preparation of TiO2 nanocrystallites by hydrolyzing with gaseous water and their photocatalytic activity

TiO2 nanocrystallites were prepared front precursors tetra-n-butyl titanate (Ti(OC4H9)(4)) and titanium tetrachloride (TiCl4). The precursors were hydrolyzed by gaseous water in autoclave, and then calcined at predetermined testing temperatures. The samples were characterized by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectra (FT-IR), and UV-vis diffuse reflectance spectra (DRS). The photocatalytic activities of the samples were evaluated by the photobleaching of methylene blue (MB) in aqueous solution and the photocatalytic oxidation of propylene in gas phase at ambient temperature. The results showed that the anatase phase nanocrystalline TiO2 could be obtained at relatively low temperatures (for precursor Ti(OC4H9)4 at I I VC and for TiCl4 at 140 degrees C, respectively), and that the as prepared samples exhibited high photocatalytic activities to photobleach MB in aqueous solution. As the calcination temperatures increasing. the decolor ratio of MB increased and reached the maximum value of nearly 100% at 600 degrees C, and then decreased. The photobleaching of MB by all samples followed the pseudo-first-order kinetics with respect to MB concentration.

Sol-gel thin-film immobilized soybean peroxidase biosensor for the amperometric determination of hydrogen peroxide in acid medium

An acid-stable soybean-peroxidase biosensor was devel oped by immobilizing the enzyme in a sol-gel thin film. Methylene blue was used as a mediator because of its high electron-transfer efficiency. The sol-gel thin film and enzyme membrane were characterized by FT-IR, and the effects of pH, operating potential, and temperature were explored for optimum analytical performance by using the amperometric method. The H2O2 sensor exhibited a fast response (5 s), high sensitivity (27.5 mu A/mM), as well as good thermostability and long-term stability. In addition, the performance of the biosensor was investigated using flow-injection analysis (FIA).

ELECTROCATALYTIC OXIDATION OF REDUCED NICOTINAMIDE COENZYMES AT ORGANIC DYE-MODIFIED ELECTRODES

Chemically modified electrodes (CMEs) were prepared by adsorbing different dyes, including methylene blue (MB), toluidine blue (TB) and brilliant cresyl blue (BCB), onto glassy carbon electrodes (GCE) with anodic pretreatment. The electrochemical reactions of adsorbed dyes are fairly reversible at low coverages. The CMEs are more stable in acid solutions than in alkaline ones, which is mainly due to decomposition of the dyes in the latter media. They exhibit an excellent catalytic ability for the oxidation of nicotinamide coenzymes (NADH and NADPH). The formation of a charge transfer complex between the coenzyme and the adsorbed mediator has been demonstrated using a rotating disk electrode. The charge transfer complex decomposition is a slow step in the overall electrode reaction process. Some kinetic parameters are estimated. Dependence of the electrocatalytic activity of the CMEs on the solution pH is discussed.