Finite element method for a nonsmooth elliptic equation

In this paper, we study the finite element method for a non-smooth elliptic equation. Error analysis is presented, including a priori and a posteriori error estimates as well as superconvergence analysis. We also propose two algorithms for solving the underlying equation. Numerical experiments are employed to confirm our error estimations and the efficiency of our algorithms.     

Liquid-liquid extraction coupled with LC/MS/MS for monitoring of malonyl-CoA in rat brain tissue

The formation of malonyl-CoA is catalyzed by acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of de novo fatty acid synthesis. Monitoring the changes of malonyl-CoA concentration in the brain in response to treatments such as pharmaceutical intervention (via ACC inhibitors) or different dietary conditions (such as varied feeding regimes) is of great interest and could help increase the understanding of how this molecule contributes to feeding behavior and overall energy balance. We have developed a sensitive analytical method for the determination of malonyl-CoA levels in rat brain tissue. The assay involved removal of tissue lipids by liquid-liquid extraction followed by LC/MS/MS analysis of the aqueous layer for malonyl-CoA. The method was sensitive enough (limit of quantitation = 50 ng/mL, or approximately 0.018 nmol/g brain tissue) to determine malonyl-CoA in individual rat brain preparations. The assay performance was sufficiently rugged to support drug discovery screening efforts and provided an additional analytical tool for monitoring brain malonyl-CoA levels.     

Recovery type a posteriori error estimates in finite element methods

This is a survey article on finite elementa posteriori error estimates with an emphasize on gradient recovery type error estimators. As an example, the error estimator based on the ZZ patch recovery technique will be discussed in some detail.     

A posteriori error estimates of constrained optimal control problem governed by convection diffusion equations

In this paper, we study a posteriori error estimates of the edge stabilization Galerkin method for the constrained optimal control problem governed by convection-dominated diffusion equations. The residual-type a posteriori error estimators yield both upper and lower bounds for control u measured in L ²-norm and for state y and costate p measured in energy norm. Two numerical examples are presented to illustrate the effectiveness of the error estimators provided in this paper.      

Electrochemical DNA biosensors based on platinum nanoparticles combined carbon nanotubes

Platinum nanoparticles were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical DNA biosensor. Multi-walled carbon nanotubes and platinum nanoparticles were dispersed in Nafion, which were used to fabricate the modification of the glassy carbon electrode (GCE) surface. Oligonucleotides with amino groups at the 5′ end were covalently linked onto carboxylic groups of MWCNTs on the electrode. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated daunomycin. Due to the ability of carbon nanotubes to promote electron-transfer reactions, the high catalytic activities of platinum nanoparticles for chemical reactions, the sensitivity of presented electrochemical DNA biosensors was remarkably improved. The detection limit of the method for target DNA was 1.0 × 10⁻¹¹ mol l⁻¹.     

Tris(2,2′-bipyridyl)cobalt(III)-doped silica nanoparticle DNA probe for the electrochemical detection of DNA hybridization

A new and sensitive electrochemical DNA hybridization detection assay, using tris(2,2′-bipyridyl)cobalt(III) [Co(bpy)₃³⁺]-doped silica nanoparticles as the oligonucleotide (ODN) labeling tag, and based on voltammetric detection of Co(bpy)₃³⁺ inside silica nanoparticles, is described. Electro-active Co(bpy)₃³⁺ is not possible for directly linking with DNA, it is doped into the silica nanoparticles in the process of nanoparticles synthesis for DNA labeling with trimethoxysilylpropydiethylenetriamine (DETA) and glutaraldehyde as linking agents. The Co(bpy)₃³⁺ labeled DNA probe is used to hybridize with target DNA immobilized on the surface of glassy carbon electrode. Only the complementary sequence DNA (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe labeled with Co(bpy)₃³⁺ and give an obvious electrochemical response. A three-base mismatch sequence and non-complementary sequence had negligible response. Due to the large number of Co(bpy)₃³⁺ molecules inside silica nanoparticles linked to oligonucleotide DNA probe, the assay showed a high sensitivity. It allows the detection at levels as low as 2.0×10⁻¹⁰ mol l⁻¹ of the target oligonucleotides.     

Solution-processible Cd-doped ZnO nanoparticles as an electron transport layer to achieve high performance polymer solar cells through improve conductivity and light transmittance

Abstract

In this work, electron transport layers (ETLs) with high charge transfer ability were prepared by doping ZnO nanoparticles with different concentrations of cadmium(Cd). The inverted polymer solar cell based on PTB7-Th: PC₇₁BM as active layer and various concentrations Cd-doped ZnO (CZO) as ETLs were fabricated. The PCE of the device with optimized Cd content in the ZnO film was about 14.7% larger than that of the pure ZnO-based cells. The cadmium-doped ZnO(CZO) is a good candidate to be used as a high-quality transparent electrode in solar cell applications.     

Co-Production of Isoprene and Lactate by Engineered Escherichia coli in Microaerobic Conditions

Lactate and isoprene are two common monomers for the industrial production of polyesters and synthetic rubbers. The present study tested the co-production of D-lactate and isoprene by engineered Escherichia coli in microaerobic conditions. The deletion of alcohol dehydrogenase (adhE) and acetate kinase (ackA) genes, along with the supplementation with betaine, improved the co-production of lactate and isoprene from the substrates of glucose and mevalonate. In fed-batch studies, microaerobic fermentation significantly improved the isoprene concentration in fermentation outlet gas (average 0.021 g/L), compared with fermentation under aerobic conditions (average 0.0009 g/L). The final production of D-lactate and isoprene can reach 44.0 g/L and 3.2 g/L, respectively, through fed-batch microaerobic fermentation. Our study demonstrated a dual-phase production strategy in the co-production of isoprene (gas phase) and lactate (liquid phase). The increased concentration of gas-phase isoprene could benefit the downstream process and decrease the production cost to collect and purify the bio-isoprene from the fermentation outlet gas. The proposed microaerobic process can potentially be applied in the production of other volatile bioproducts to benefit the downstream purification process.     

碘分子高激发态光学双共振多光子离化光谱

本文利用双色双共振多光子离化技术（ＯＯＤＲ－ＭＰＩ）,对Ｉ２分子离子对态Ｆ０＋ｕ态进行了较为仔细的研究,利用已知的分子常数,对所得谱线进行了标识和归属,将Ｔｅ＝５２４００ｃｍ－１,间隔为３７ｃｍ－１的振动序列归属为Ｆ０＋ｕ态的高振动激发态,并确定了多光子激发及离化的跃迁通道     

Pt-Ce掺杂对Cu/Al2O3催化剂结构及性能的影响及其用于苯催化氧化的研究

通过添加Pt-Ce作为助剂,对Al2O3担载的Cu催化剂进行修饰,制备负载型催化剂用于苯的催化氧化。利用XRD,N2吸附和H2-TPR等手段对载体和催化剂的织构-结构、活性组分的分散、还原性能及活性组分之间的相互作用进行了表征和分析。结果表明:添加Pt与Ce有利于提高CuO颗粒在Al2O3表面上的分散度,使其晶粒变小,从而改善了催化剂的性能。部分活性组分进入到Al2O3孔道中,在孔中及表面均形成了活性氧化物种。添加微量的Pt(0.1%(质量分数))及Ce可明显提高Cu/Al2O3催化剂的氧化活性,其中0.1%Pt/10%CuCe(12∶1)/Al2O3在250℃下就能完全催化氧化苯,表现出最佳的催化活性,可与贵金属催化剂(通常负载量在0.3%～2.0%)的活性相媲美。催化剂的高活性主要是在于活性组分在Al2O3表面的高分散以及PtOx,CuO和CeO2之间的相互作用。