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101.
Sang-Eun?Lee Tae-Min?Jo Hyang-Yeol?Lee Jongsung?Lee Kyung-Hwan?JungEmail author 《Applied biochemistry and biotechnology》2013,171(6):1299-1312
We synthesized galactosyl chlorphenesin (CPN-G) using β-gal-containing Escherichia coli (E. coli) cells in which the conversion yield of chlorphenesin (CPN) to CPN-G reached about 64 % during 12 h. CPN-G was identified and characterized using high-performance liquid chromatography, liquid chromatography-mass spectrometry, Fourier transform-infrared spectrometry, and nuclear magnetic resonance analysis (1H and 13C). We verified that a galactose was covalently bound to a CPN alcohol group during CPN-G synthesis throughout these analyses. In particular, by the hydrolysis of CPN-G using β-gal, it was confirmed that a galactose was bound to CPN. The minimal inhibitory concentration (MIC) results showed that the CPN-G MICs were fairly similar to those of CPN. HACAT cell viability was significantly higher in CPN-G-treated cells than in CPN-treated cells at concentrations of 0.0–20.0 mM. Finally, we accomplished the synthesis of less toxic CPN-G, compared with CPN, using β-gal-containing E. coli cells as whole cells without changes in the MICs against microorganisms. 相似文献
102.
Wan K. Jo Jong H. Lee 《International journal of environmental analytical chemistry》2013,93(15):1412-1424
A lesser degree of information is available with respect to microenvironments associated with potential exposure to naphthalene, in comparison with other volatile organic compounds. The current study investigated the levels of benzene as well as naphthalene, both in the indoor and outdoor air of apartments and in the cabins of passenger cars. Two groups of 20 apartment buildings (20 new and 20 old) were chosen on the basis of the selection criteria (apartment location and size). In addition, 10 actual commuters were recruited for this study. The equal number of drivers was recruited for the study for comparison of two types of fuels for vehicles (five drivers of gasoline-fuelled and five drivers of diesel-fuelled passenger cars). Indoor naphthalene concentrations were similar between old and new apartments, while the benzene concentrations in new apartments were significantly higher than those of old apartments. The naphthalene concentrations in bedrooms, where wardrobes with moth repellent (MRs) were placed, were significantly higher than those for living rooms where no MRs were present. In turn, these indoor concentrations were significantly higher than outdoor levels. It is noteworthy that the mean and median values of naphthalene measured in the bedrooms exceeded the USEPA RfC (inhalation reference concentration) of 3?µg?m?3, and the living room values were close to the RfC, while the residential benzene levels exceeded the European benzene limit of 5?µg?m?3. In contrast, the maximum outdoor levels were well below that of the RfC. The use of passenger cars appeared to be a significant daily activity for both naphthalene and benzene exposure. The naphthalene-to-benzene ratios varied with the type of microenvironments. Both the indoor naphthalene and benzene concentrations in the present study were much higher than those of other studies. 相似文献
103.
Duc Hoai Do Christophe Walgraeve Samuel Fekadu Hayleeyesus Patrick De Wispelaere Jo Dewulf 《International journal of environmental analytical chemistry》2013,93(3):298-314
The effects of urban and indoor air pollution on human health are a major environmental concern for all, but not much has been researched in the developing world. Specifically, quantitative data on the occurrence of volatile organic compounds (VOCs) – main contributors to air pollution – in Asia and Africa are scarce compared to the availability of data in the developed world. This paper presents one of the first studies focusing on the analysis and occurrence of VOCs in Vietnam and Ethiopia, which constitutes part of the novelty of this work. A spectrum of 34 VOCs was measured at eight different urban sites in Ghent (Belgium), Hanoi (Vietnam), Jimma and Addis Ababa (Ethiopia) during three sampling campaigns from September 2008 to September 2010. Sampling was done in an active way by means of sorbent tubes filled with Tenax TA. The analysis was done by TD-GC-MS using internal standard calibration. Data were interpreted and compared in terms of (i) individual, subgroup and total VOCs concentration (TVOCs), (ii) indoor-to-outdoor (I/O) concentration ratios, (iii) source identification by diagnostic ratio and/or correlation coefficients, and (iv) ozone formation potential (OFP) at outdoor sites based on up-to-date maximum incremental reactivity (MIR). I/O concentration ratios varied between 0.2 and 30, with big differences noticed with respect to the type of VOC(s) considered and the type of outdoor sampling location. The highest TVOC concentrations were measured in street samples with maximum values of 54?µg/m3 in Ghent, 507?µg/m3 in Hanoi and 318?µg/m3 in Addis Ababa illustrating the large difference in ambient air quality levels. This is also reflected in the arithmetic mean OFP values (µg/m3) of 82, 1308 and 596 in Ghent, Hanoi and Addis Ababa, respectively. Results of this study could be helpful to support formulation of national policy with regard to ambient air quality. 相似文献
104.
105.
Eun Joung Choi Eunha Kim Youngjun Lee Ala Jo Seung Bum Park 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(5):1370-1374
Fluorescence imaging enables the uniquely sensitive observation of functional‐ and molecular‐recognition events in living cells. However, only a limited range of biological processes have been subjected to imaging because of the lack of a design strategy and difficulties in the synthesis of biosensors. Herein, we report a facile synthesis of emission‐tunable and predictable Seoul‐Fluors, 9‐aryl‐1,2‐dihydrolopyrrolo[3,4‐b]indolizin‐3‐ones, with various R1 and R2 substituents by coinage‐metal‐catalyzed intramolecular 1,3‐dipolar cycloaddition and subsequent palladium‐mediated C H activation. We also showed that the quantum yields of Seoul‐Fluors are controlled by the electronic nature of the substituents, which influences the extent of photoinduced electron transfer. On the basis of this understanding, we demonstrated our design strategy by the development of a Seoul‐Fluor‐based chemosensor 20 for reactive oxygen species that was not accessible by a previous synthetic route. 相似文献
106.
The READY program: Building a global potential energy surface and reactive dynamic simulations for the hydrogen combustion 下载免费PDF全文
READY (REActive DYnamics) is a program for studying reactive dynamic systems using a global potential energy surface (PES) built from previously existing PESs corresponding to each of the most important elementary reactions present in the system. We present an application to the combustion dynamics of a mixture of hydrogen and oxygen using accurate PESs for all the systems involving up to four oxygen and hydrogen atoms. Results at the temperature of 4000 K and pressure of 2 atm are presented and compared with model based on rate constants. Drawbacks and advantages of this approach are discussed and future directions of research are pointed out. © 2014 Wiley Periodicals, Inc. 相似文献
107.
Fernando P. Carvalho João M. Oliveira M. Malta M. Eugénia Lemos 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):119-125
During the past century extensive uranium mining took place in Portugal for radium and uranium production. One such uranium mine was the Boco Mine, in operation during the 1960s and 70s. Mining waste and open pits were left uncovered since mine closure. During the nineties a quarry for sand extraction was operated in the same site and water from a local stream was extensively used in sand sieving. Downstream the mine area, agriculture soil is used for cattle grazing. Water from the stream, water wells, soil, pasture and sheep meat were now analyzed for radionuclides of uranium natural series. The U-series radionuclide 226Ra was generally the highest in concentrations especially in soil, pasture, and in internal organs of sheep. 226Ra concentrations were 1,093 ± 96 Bq/kg (dry weight, dw) in soil, 43 ± 3 Bq/kg (dw) in pasture, and 193 ± 84 mBq/kg (wet weight, ww) in muscle tissue of sheep. Other sheep internal organs displayed much higher 226Ra concentrations, such as the brain and kidneys with 1,850 ± 613 mBq/kg (ww) and 6,043 ± 6,023 mBq/kg (ww), respectively. Results of analyses of tissue samples from sheep grown in a comparison area were 2 to 16 times lower, depending on the organ. Absorbed radiation doses for internal organs were computed and may exceed 5.2 mGy/y in the case of kidneys, near three times higher than in animals from the reference area, but below the threshold for biological effects. Radionuclide transfer in the terrestrial food chain and radiation exposure of the human population is discussed. 相似文献
108.
Thanh-Thuy Nguyen-Boisse Joëlle Saulnier Nicole Jaffrezic-Renault Florence Lagarde 《Analytical and bioanalytical chemistry》2014,406(4):1039-1048
A new conductometric enzyme-based biosensor was developed for the determination of formaldehyde (FA) in aqueous solutions. The biosensor was prepared by cross-linking formaldehyde dehydrogenase from Pseudomonas putida with bovine serum albumin in saturated glutaraldehyde vapours (GA) at the surface of interdigitated gold microelectrodes. Nicotinamide adenine dinucleotide cofactor (NAD+) was added in solution at each measurement to maintain enzyme activity. Addition of a Nafion layer over the enzyme modified electrode resulted in a significant increase of biosensor signal due to enhanced accumulation of protons generated by enzymatic reaction at the electrode surface. Different parameters affecting enzyme activity or playing a role in ionic transfer through the Nafion membrane were optimised. In optimal conditions (0.045 mg enzyme, 30 min exposure to GA, 0.3 μL of a 1 % (v/v) Nafion solution deposit, measurement in 5 mM phosphate buffer pH 7 containing 20 μM NAD+), the biosensor signal was linear up to 10 mM FA, and the detection limit was 18 μM. Relative standard deviations calculated from five consecutive replicates of FA solutions were lower than 5 % in the 1–10 mM range. The biosensor was successfully applied to the determination of FA in spiked water samples (tap water and Rhone river water), with recoveries in the 95–110 % range. Figure
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109.
Silk‐Pectin Hydrogel with Superior Mechanical Properties,Biodegradability, and Biocompatibility 下载免费PDF全文
Keiji Numata Shoya Yamazaki Takuya Katashima Jo‐Ann Chuah Naofumi Naga Takamasa Sakai 《Macromolecular bioscience》2014,14(6):799-806
A new method is developed to prepare silk hydrogels and silk‐pectin hydrogels via dialysis against methanol to obtain hydrogels with high concentrations of silk fibroin. The relationship between the mechanical and biological properties and the structure of the silk‐pectin hydrogels is subsequently evaluated. The present results suggest that pectin associates with silk molecules when the silk concentration exceeds 15 wt%, suggesting that a silk concentration of over 15 wt% is critical to construct interacting silk‐pectin networks. The silk‐pectin hydrogel reported here is composed of a heterogeneous network, which is different from fiber‐reinforced, interpenetrated networks and double‐network hydrogels, as well as high‐stiffness hydrogels (elastic modulus of 4.7 ± 0.9 MPa, elastic stress limit of 3.9 ± 0.1 MPa, and elastic strain limit of 48.4 ± 0.5%) with regard to biocompatibility and biodegradability. 相似文献
110.
Daniel F. Kienle João V. de Souza Erik B. Watkins Tonya L. Kuhl 《Analytical and bioanalytical chemistry》2014,406(19):4725-4733
The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5?±?0.6 Å and 1.485?±?0.007 for DPPE monolayers, and 23.9?±?0.5 Å and 1.478?±?0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection. Figure
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