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Lu Wang, Weiyu Song, Jianlin Deng, Huiling Zheng, Jian Liu, Zhen Zhao, Manglai Gao, Yuechang Wei
The photocatalytic N2O dissociation on anatase TiO2 is an attractive reaction and the mechanism of the photocalytic process, the role of excited electrons, and the favorable facet for higher activity need a more detailed study at the molecular level. Using DFT + U calculations, we investigate the dissociation process of N2O into N2 with and without photoexcited electrons on anatase TiO2 (001) and (101) facets to unravel such puzzles. The optical absorption properties of TiO2 (001) and (101) facets are compared in combination with electronic analysis...
March 15, 2018: Nanoscale
V Lew, E McKay, M Maze
Introduction: For a drug that has been omnipresent for nearly 200 years, nitrous oxide's (N2O) future seems less certain than its illustrious past. Environmental concerns are coming to the fore and may yet outweigh important clinical benefits. Sources of data: After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered. Areas of agreement: The analgesic and anaesthetic advantages of N2O remain despite a plethora of newer agents...
March 1, 2018: British Medical Bulletin
Laboni Das, Rahul Kumar, Dilip Kumar Maity, Soumyakanti Adhikari, Surajdevprakash B Dhiman, James F Wishart
A pulse radiolysis study on pyrrolidinium cation-based ionic liquids is presented herein. Time-resolved absorption spectra for 1-methyl-1-propylpyrrolidinium dicyanamide (DCA) at 500 ns after the electron pulse show broad absorption bands at wavelengths below 440 nm and at 640 nm. In pyrrolidinium bis(trifluoromethylsulphonyl)imide (NTf2) and tris(perfluoroethyl)trifluorophosphate (FAP) ILs, the transient absorption below 440nm is much weaker. The absorption at 500ns, which increases with wavelength from 500 nm to beyond 800 nm, was assigned to the tail of the solvated electron NIR absorption spectrum, since it disappears in the presence of N2O...
March 6, 2018: Journal of Physical Chemistry. A
Tiening Jin, Junchao Zhou, Zelun Wang, Ricardo Gutierrez-Osuna, Charles Ahn, Wonjun Hwang, Ken Park, Pao Tai Lin
Real-time gas analysis on-a-chip was demonstrated using a mid-infrared (mid-IR) microcavity. Optical apertures for the microcavity were made of ultrathin silicate membranes embedded in a silicon chip using the complementary metal-oxide-semiconductor (CMOS) process. Fourier transform infrared spectroscopy (FTIR) shows that the silicate membrane is trans-parent in the range 2.5 - 6.0 µm, a region that overlaps with multiple characteristic gas absorption lines and therefore enables gas detection applications...
March 6, 2018: Analytical Chemistry
Basema Balasiny, Matthew D Rolfe, Claire Vine, Charlene Bradley, Jeffrey Green, Jeff Cole
Synthesis of the Escherichia coli YtfE protein, also known as RIC, for the repair of damaged iron centres, is highly induced during anaerobic growth under conditions of nitrosative stress. How YtfE repairs nitrosative damage remains unclear. Contrary to previous reports, we show that strains defective in YtfE that lack the high-affinity NO reductase activity of the hybrid cluster protein (Hcp) are less sensitive to nitrosative stress than isogenic ytfE+ strains, which are extremely sensitive. Evidence that this sensitivity is due to YtfE-dependent release of NO into the cytoplasm includes: relief of growth inhibition by PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide), which degrades NO; relief of nitrosative stress by deletion of narG encoding the nitrate reductase that is the major source of NO from nitrite; partial suppression of nitrosative stress due to loss of Hcp function by a further mutation in ytfE; YtfE-dependent loss of aconitase and fumarase activities in the absence of Hcp; and YtfE-dependent relief of NsrR repression of the hcp promoter in response to cytoplasmic NO...
March 1, 2018: Microbiology
Daofu Yuan, Shengrui Yu, Ting Xie, Wentao Chen, Siwen Wang, Yuxin Tan, Tao Wang, Kaijun Yuan, Xueming Yang, Xingan Wang
We report the study of photodissociation dynamics of nitrous oxide in the vacuum ultraviolet region, using the time-sliced velocity map ion imaging technique. Ion images of the O(1S0) and O(3PJ = 2,1,0) products were measured at nine photolysis wavelengths from 142.55 to 148.79 nm. The product channels O(1S0) + N2(X1Σg+) and O(3PJ = 2,1,0) + N2(A3Σu+) have been observed. For these dissociation channels, the total kinetic energy releases of the dissociated products were acquired. With vibrational structures of the N2 co-products partially resolved in the experimental images, the branching ratios of different vibrational states of the N2 co-products were determined; and the vibrational state specific anisotropy parameters (β values) were derived...
February 26, 2018: Journal of Physical Chemistry. A
Miriam B Herold, Madeline E Giles, Colin J Alexander, Elizabeth M Baggs, Tim J Daniell
Denitrification is a key process responsible for the majority of soil nitrous oxide (N2O) emissions but the influences of pH and cultivation on the soil denitrifier community remain poorly understood. We hypothesised that the abundance and community structure of the total bacterial community and bacterial denitrifiers would be pH sensitive and that nirK and nirS containing denitrifiers would differ in their responses to change in pH and cultivation. We investigated the effect of long-term pH adjusted soils (ranging from pH 4...
February 19, 2018: FEMS Microbiology Letters
Ioline D Henter, Rafael Teixeira de Sousa, Carlos A Zarate
Both preclinical and clinical studies have implicated glutamatergic system dysfunction in the pathophysiology of mood disorders such as bipolar depression and major depressive disorder. In particular, rapid reductions in depressive symptoms have been noted in response to subanesthetic doses of the glutamatergic modulator ketamine in subjects with major depressive disorder or bipolar depression. These results have prompted the repurposing or development of other glutamatergic modulators, both as monotherapy or adjunctive to other therapies...
February 20, 2018: Harvard Review of Psychiatry
María J Torres, Sergio Avila, Eulogio J Bedmar, María J Delgado
The alfalfa endosymbiont Ensifer meliloti strain1021 is known to be an incomplete denitrifier due to its inability to grow anoxically using nitrate as respiratory substrate to produce ATP and grow under anoxic conditions. Although this bacterium contains and expresses the complete set of denitrification genes napEFDABC, nirK, norECBQD and nosRZDFYLX encoding the periplasmic nitrate reductase (Nap), Cu-containing nitrite reductase (NirK), c-type nitric oxide (cNor) and nitrous oxide reductase (Nos), respectively, the reasons of its inability to grow under anoxic conditions are still very poorly understood...
February 16, 2018: FEMS Microbiology Letters
Evgenii Stoyanov, Irina S Stoyanova
Experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB11F11), showed that basicity of SO2 is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H-bonds of the polymeric acid and to form a mixture of solid mono- and disolvates, LH+‧‧‧An- and L-H+-L. With a decrease in the basicity of L = CO (via C), N2O, and CO (via O), only proton monosolvates are formed, which approach L-H+-An species with convergence of the strengths of bridged H-bonds...
February 19, 2018: Angewandte Chemie
Jincheol Kim, Taegyu Kim
Performance and endurance of the Ru catalyst were studied for nitrous oxide monopropellant thruster system. The thermal decomposition of N2O requires a considerably high temperature, which make it difficult to be utilized as a thruster propellant, while the propellant decomposition temperature can be reduced by using the catalyst through the decomposition reaction with the propellant. However, the catalyst used for the thruster was frequently exposed to high temperature and high-pressure environment. Therefore, the state change of the catalyst according to the thruster operation was analyzed...
February 1, 2018: Journal of Nanoscience and Nanotechnology
Linyan Xu, Shuangbei Qian, Yuan Xie, Enxiu Wu, Haicheng Hei, Zhihong Feng, Sen Wu, Xiaodong Hu, Tong Guo, Daihua Zhang
Two-dimensional transition metal dichalcogenides (2D TMDCs) have been widely applied to electronic and optoelectronic device owing to their remarkable material properties. Many studies present the platform for regulating the contact resistance via various doping schemes. Here, we report the alteration of mechanical properties of few top layers of the WSe2 flake which are processed by air stable n-doping of N2O with a constant gas flow through mild plasma and present better manufacturability and friability. The single-line nanoscratching experiments on the WSe2 flakes with different doping time reveal that the manufacturable depths are positively correlated with the exposure time at a certain range and tend to be stable afterwards...
February 15, 2018: Nanotechnology
Xi Lu, Tiago Duarte Santos Pereira, Hussein Alhazmi, Joanna Majtacz, Qi Zhou, Li Xie, Jacek Makinia
A mechanistic model was developed as an extension of the Activated Sludge Model No. 1 to describe three nitrous oxide (N2O) production pathways in a laboratory-scale anammox-enriched granular sequencing batch reactor. Heterotrophic denitrification and two processes mediated by ammonia oxidizing bacteria (AOB), i.e. ammonia (NH4+) oxidation via hydroxylamine (NH2OH) and autotrophic denitrification, were considered. A systematic model calibration and validation protocol was developed to obtain a unique set of kinetic parameters in the extended model...
February 13, 2018: Environmental Science & Technology
Brian J Cook, Chun-Hsing G Chen, Kenneth G Caulton
The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H2L)CoCl2, is dehydrohalogenated twice by LiN(SiMe3)2 in the presence of PEt3 to give monomeric S = 1/2 LCo(PEt3)2, fully characterized in solid and solution as a square pyramidal monomer with a long axial Co-P bond. This 17 electron species reacts in time of mixing with N2O to form L2Co2(OPEt3) + 3 OPEt3, the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O2, and divalent cobalt persists even in the presence of excess oxidant...
February 13, 2018: Chemistry: a European Journal
Jinyun Yuan, Wenhua Zhang, Xingxing Li, Jinlong Yang
Employing first principles calculations, we show a two-step reaction mechanism for direct methane oxidation to methanol over a single atom Co-embedded graphene (Gr) catalyst, with N2O as the O-donor molecule. C-H activation is the rate-limiting step. The high reaction activity and selectivity under mild conditions were predicted for this catalyst.
February 13, 2018: Chemical Communications: Chem Comm
Juejie Yang, Guanghe Li, Yi Qian, Yunfeng Yang, Fang Zhang
Linking microbial community structure to physiology and ecological processes is a critical focus of microbial ecology. To understand the microbial functional gene patterns related to soil greenhouse gas [carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)] emissions under oil contamination, we used functional gene array (GeoChip 5.0) analysis and network methods to investigate the feedback responses of soil microbial functional gene patterns and identify keystone genes in Shengli Oilfield, China. The microbial functional gene number, relative abundance and diversity involved in carbon degradation and nitrogen cycling decreased consistently with the reduced CO2 and N2O flux in oil contaminated soils, whereas the gene number and relative abundance of methane-production related genes increased with contamination...
February 8, 2018: Science of the Total Environment
Tiehu He, Deyan Liu, Junji Yuan, Jiafa Luo, Stuart Lindsey, Nanthi Bolan, Weixin Ding
The effects of biochar combined with the urease inhibitor, hydroquinone, and nitrification inhibitor, dicyandiamide, on gaseous nitrogen (N2O, NO and NH3) emissions and wheat yield were examined in a wheat crop cultivated in a rice-wheat rotation system in the Taihu Lake region of China. Eight treatments comprised N fertilizer at a conventional application rate of 150kgNha-1 (CN); N fertilizer at an optimal application rate of 125kgNha-1 (ON); ON+wheat-derived biochar at rates of 7.5 (ONB1) and 15tha-1 (ONB2); ON+nitrification and urease inhibitors (ONI); ONI+wheat-derived biochar at rates of 7...
February 8, 2018: Science of the Total Environment
Lei Wu, Xian Wu, Shan Lin, Yupeng Wu, Shuirong Tang, Minghua Zhou, Muhammad Shaaban, Jinsong Zhao, Ronggui Hu, Yakov Kuzyakov, Jinshui Wu
Rice paddy conversion to vegetable production is a common agricultural practice driven by economic benefits and shifting diets. However, little is known on the initial effects of this land-use conversion on net ecosystem carbon budget (NECB) and greenhouse gas (GHG) balance. Annual NECB and emissions of CH4 and N2O were measured from a native double rice cropping system (Rice) and a vegetable field recently converted from rice paddy (Veg) under no nitrogen (N) fertilization (Rice-N0 and Veg-N0) and conventional N fertilization (Rice-N+ and Veg-N+) during the initial four years upon conversion in subtropical China...
January 27, 2018: Science of the Total Environment
Shuang Wu, Jie Chen, Chen Li, Delei Kong, Kai Yu, Shuwei Liu, Jianwen Zou
Agricultural nitrate leaching and runoff incurs high nitrogen loads in agricultural irrigation watersheds, constituting one of important sources of atmospheric nitrous oxide (N2O). Two independent sampling campaigns of N2O flux measurement over diel cycles and N2O flux measurements once a week over annual cycles were carried out in an agricultural irrigation watershed in southeast China using floating chamber (chamber-based) and gas transfer equation (model-based) methods. The diel and seasonal patterns of N2O fluxes did not differ between the two measurement methods...
February 7, 2018: Environmental Monitoring and Assessment
Monica Conthe, Lea Wittorf, J Gijs Kuenen, Robbert Kleerebezem, Mark C M van Loosdrecht, Sara Hallin
Reduction of the greenhouse gas N2O to N2 is a trait among denitrifying and non-denitrifying microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor...
February 7, 2018: ISME Journal
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