Total synthesis of AI-77-B

A new stereoselective approach for the synthesis of AI-77-B has been described. Dihydroisocoumarin fragment was made in two routes using Heck reaction followed by oxidation of the olefin and LDA mediated reaction. The chiral amino acid moiety has been obtained from d-ribose involving Grignard reaction on ribosylimine. Finally, condensation of dihydroisocoumarin with acid fragment furnished the title target AI-77-B.     

Quantum -modules and generalized mirror transformations

In the previous paper [Hiroshi Iritani, Quantum D-modules and equivariant Floer theory for free loop spaces, Math. Z. 252 (3) (2006) 577–622], the author defined equivariant Floer cohomology for a complete intersection in a toric variety and showed that it is isomorphic to the small quantum D-module after a mirror transformation when the first Chern class c₁(M) of the tangent bundle is nef. In this paper, even when c₁(M) is not nef, we show that the equivariant Floer cohomology reconstructs the big quantum D-module under certain conditions on the ambient toric variety. The proof is based on a mirror theorem of Coates and Givental [T. Coates, A.B. Givental, Quantum Riemann — Roch, Lefschetz and Serre, Ann. of Math. (2) 165 (1) (2007) 15–53]. The reconstruction procedure here gives a generalized mirror transformation first observed by Jinzenji in low degrees [Masao Jinzenji, On the quantum cohomology rings of general type projective hypersurfaces and generalized mirror transformation, Internat. J. Modern Phys. A 15 (11) (2000) 1557–1595; Masao Jinzenji, Co-ordinate change of Gauss–Manin system and generalized mirror transformation, Internat. J. Modern Phys. A 20 (10) (2005) 2131–2156].     

Detection of PCB77 by Antibody-Coated Competitive Fluorescent Quantitative Immuno-PCR Using Molecular Beacon

Abstract

A rapid and quantitative technique is urgently needed in detecting toxicological and carcinogenic polychlorinated biphenyls (PCBs) in the environment. In this study, a high sensitive real time fluorescent quantitative immuno-PCR (FQ-IPCR) approach using molecular beacon (MB) was developed to detect PCB77, which was classified as a human carcinogen. MB-based FQ-IPCR was then performed on serial dilutions of known PCB77 concentrations equivalent to 10-fold dilutions of 10–10⁵ fg/mL. A correlation coefficient of 0.997 was identified, and a linear relationship between 10 fg/mL and 100 pg/mL, with y = 0.543x + 21.779, was obtained. Three soil samples were determined by MB-based FQ-IPCR to proof the validity of the method, and the results of which were further confirmed by conventional enzyme-linked immuno sorbent assay (ELISA). Based on sensitivity and reproduction, the MB-based real time FQ-IPCR technique will become a promising monitoring tool for environmental endocrine disruptors.     

Microbial degradation of poly(butylene succinate) by Fusarium solani in soil environments

The use of mulch made of biodegradable plastic in agriculture is expected to help solve the problem of the enormous amount of plastic waste emission, and to save the labor of removing the mulch after harvesting crops. In this study, we isolated a microorganism possessing the ability to degrade one of the promising biodegradable plastics, poly(butylene succinate) (PBS), and investigated the degradation characteristics of the microorganism in soil environments. Fungal strain WF-6, belonging to Fusarium solani, that had not been reported could be isolated from farmland as the PBS-degrading microorganism. Strain WF-6 degraded 2.8 percent of the PBS in a 14-day experimental run in a sterile soil environment, as determined by measuring CO₂ evolution. Furthermore, we ascertained that the degradability of strain WF-6 was enhanced by co-culturing with the newly isolated bacterial strain Stenotrophomonas maltophilia YB-6, which itself does not show PBS-degrading activity. We then investigated the effects of cell density of the indigenous microorganisms in the soil environments on the degradability of the co-culture of strains WF-6 and YB-6 by inoculating these strains into non-sterilized and partially sterilized soils, which contained 10⁸, 10⁶, and 10³ CFU/g-dry solid of soil of indigenous microorganisms. The degradability strongly depended on the cell density level of the indigenous microorganisms and was remarkably diminished when the cell concentration level was the highest, 10⁸ CFU/g-dry solid. Quantitative PCR analysis revealed that the growth of strains WF-6 and YB-6 was inhibited in the non-sterile soil environment with the highest cell density level of the indigenous microorganisms.     

On wavelets related to the Walsh series

For any integers p,n≥2 necessary and sufficient conditions are given for scaling filters with pⁿ many terms to generate a p-multiresolution analysis in . A method for constructing orthogonal compactly supported p-wavelets on is described. Also, an adaptive p-wavelet approximation in is considered.     

一步法制备银溶胶用于临床嗜麦芽窄食单胞菌的表面增强拉曼光谱快速检测

该文利用一步法快速制备银溶胶,实现了基底的现用现制.对嗜麦芽窄食单胞菌进行表面增强拉曼散射(SERS)检测,得到18组拉曼特征峰的生物指纹谱图.方法能够检测到的最低菌悬液浓度为5 x106菌落形成单位(CFU)/mL,重现性的相对标准偏差为6.8％-16％,满足生物医学领域定性分析的基本要求.采用该方法获得的阳性病人血...     

Unraveling the carbene chemistry of oxymethylene ethers: Experimental investigation and kinetic modeling of the high-temperature pyrolysis of OME-2

Oxymethylene ethers (OMEs) form an interesting family of synthetic compounds to replace fossil fuels. This alternative liquid energy carrier can contribute to a circular carbon economy when produced via carbon capture and utilization technology using renewable electricity. Despite the potential to reduce greenhouse gas and particulate matter emissions and their ideal ignition characteristics, little is known about the thermal decomposition behavior of OMEs. In this work, new insights are obtained in the pyrolysis chemistry of oxymethylene ether-2 (OME-2) and the role of carbenes by performing experiments at high temperatures (> 850 K) in a tubular quartz reactor. The used continuous bench-scale pyrolysis unit has a dedicated on-line analysis section including comprehensive two-dimensional gas chromatography (GC $\times$ GC) coupled with flame ionization detection (FID) and mass spectroscopy (MS) to identify and quantify the full product spectrum over the complete temperature range. The reactor temperature was varied between 850 and 1150 K at a fixed pressure of 0.15 MPa and residence times of 400 to 850 ms. The major products are dimethoxymethane, formaldehyde, methyl formate, methane, CO₂, CO and H₂. Minor intermediate compounds comprise dimethyl ether, formic anhydride, formic acid, methoxymethyl formate and methoxymethanol. The yields of compounds with carbon-carbon bonds are low since no such bonds originally occur in OME-2. Precursors of aromatic compounds and soot particles are absent in the reactor effluent. The experimental results are simulated with a new first principles-based kinetic model for pyrolysis and combustion of OME-2. This model can predict the experimental trends of major products on average within the experimental uncertainty margin of ± 10% relative for major product species. A reaction pathway and sensitivity analysis are presented to highlight the importance of the carbenes for initiation of the radical chemistry under pyrolysis conditions.