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排序方式: 共有197条查询结果,搜索用时 46 毫秒
191.
Dixit P Mukherjee PK Sherkhane PD Kale SP Eapen S 《Journal of hazardous materials》2011,192(1):270-276
Plants can be used for remediation of polyaromatic hydrocarbons, which are known to be a major concern for human health. Metabolism of xenobiotic compounds in plants occurs in three phases and glutathione transferases (GST) mediate phase II of xenobiotic transformation. Plants, although have GSTs, they are not very efficient for degradation of exogenous recalcitrant xenobiotics including polyaromatic hydrocarbons. Hence, heterologous expression of efficient GSTs in plants may improve their remediation and degradation potential of xenobiotics. In the present study, we investigated the potential of transgenic tobacco plants expressing a Trichoderma virens GST for tolerance, remediation and degradation of anthracene—a recalcitrant polyaromatic hydrocarbon. Transgenic plants with fungal GST showed enhanced tolerance to anthracene compared to control plants. Remediation of 14C uniformly labeled anthracene from solutions and soil by transgenic tobacco plants was higher compared to wild-type plants. Transgenic plants (T0 and T1) degraded anthracene to naphthalene derivatives, while no such degradation was observed in wild-type plants. The present work has shown that in planta expression of a fungal GST in tobacco imparted enhanced tolerance as well as higher remediation potential of anthracene compared to wild-type plants. 相似文献
192.
Proteins catalyze specific chemical reactions and carry out highly selective molecular recognition because they adopt well-defined three-dimensional structures and position chemically reactive functional groups in specific constellations. Proteins attain these well-defined structures through the complex process of protein folding. We seek to emulate these protein functions by constructing macromolecules that are easier to engineer by avoiding folding altogether. Toward that goal, we have developed an approach for the synthesis of macromolecules with programmable shapes. As described in this Account, we have constructed synthetic building blocks called bis-amino acids that we then couple through pairs of amide bonds to create water-soluble, spiroladder oligomers (bis-peptides) with well-defined three-dimensional structures. Bis-peptides use the conformational preferences of fused rings, stereochemistry, and strong covalent bonds to define their shape, unlike natural proteins and synthetic foldamers, which depend on noncovalent interactions and an unpredictable folding process to attain structure. Using these bis-amino acid monomers, we have built and characterized a number of bis-peptide nanostructures. We also constructed a molecular actuator that undergoes a large change in conformation under the control of metal exchange; the first application of bis-peptides. We are currently developing further approaches to functionalize bis-peptides as scaffolds to present well-defined constellations of functional groups. Such macromolecules could facilitate multifunctional catalysis and molecular recognition and lead to nanoscale molecular devices. 相似文献
193.
A double-lane four-arm roundabout, where traffic movement is continuous in opposite directions and at different speeds, produces a zone responsible for recirculation of emissions within a road section creating canyon-type effect. In this zone, an effect of thermally induced turbulence together with vehicle wake dominates over wind driven turbulence causing pollutant emission to flow within, resulting into more or less equal amount of pollutants upwind and downwind particularly during low winds. Beyond this region, however, the effect of winds becomes stronger, causing downwind movement of pollutants. Pollutant dispersion caused by such phenomenon cannot be described accurately by open-terrain line source model alone. This is demonstrated by estimating one-minute average carbon monoxide concentration by coupling an open-terrain line source model with a street canyon model which captures the combine effect to describe the dispersion at non-signalized roundabout. The results of the modeling matched well with the measurements compared with the line source model alone and the prediction error reduced by about 50%. The study further demonstrated this with traffic emissions calculated by field and semi-empirical methods. 相似文献
194.
Thakur Surendra Singh Pradhan Sharad K. Sehgal Shankar Saxena Kuldeep K. 《SILICON》2023,15(1):583-601
Silicon - In this study, silicon carbide mixed electrical discharge machining (SCMEDM) process has been developed and later on modelled also using an artificial neural network (ANN) based technique... 相似文献
195.
Roman M. Dickey Michaela A. Jones Neil D. Butler Ishika Govil Aditya M. Kunjapur 《American Institute of Chemical Engineers》2023,69(12):e18230
Deconstruction of polyethylene terephthalate (PET) plastic waste generates opportunities for valorization to alternative products. We recently designed an enzymatic cascade that could produce terephthalaldehyde (TPAL) from terephthalic acid. Here, we showed that the addition of TPAL to growing cultures of Escherichia coli wild-type strain MG1655 and an engineered strain for reduced aromatic aldehyde reduction (RARE) strain resulted in substantial reduction. We then investigated if we could mitigate this reduction using multiplex automatable genome engineering (MAGE) to create an E. coli strain with 10 additional knockouts in RARE. Encouragingly, we found this newly engineered strain enabled a 2.5-fold higher retention of TPAL over RARE after 24 h. We applied this new strain for the production of para-xylylenediamine (pXYL) and observed a 6.8-fold increase in pXYL titer compared with RARE. Overall, our study demonstrates the potential of TPAL as a versatile intermediate in microbial biosynthesis of chemicals that derived from waste PET. 相似文献
196.
Silicon - The objective of the current review article is (i) To help people to come across and to understand the various Mineral Trioxide Aggregates (MTA)-like silicate-based materials, including... 相似文献
197.
Keserwani Pankaj Kumar Govil Mahesh Chandra Pilli Emmanuel S. 《Neural computing & applications》2023,35(7):4993-5013
Neural Computing and Applications - The technological advancement leads to an increase in the usage of the Internet with many applications and connected devices. This increased network size causes... 相似文献