We consider three recent large-scale calculations for the radiative and electron-impact excitation data of N IV, carried out with different methods and codes. The scattering calculations employed the relativistic Dirac R-matrix (DARC) method, the intermediate coupling frame transformation (ICFT) R-matrix method, and the B-spline R-matrix (BSR) method. These are all large-scale scattering calculations with well-tested and sophisticated codes, which use the same set of target states. One concern raised in previous literature is related to the increasingly large discrepancies in the effective collision strengths between the three sets of calculations for increasingly weak and/or high-lying transitions. We have built three model ions and calculated the intensities of all the main spectral lines in this ion. We have found that, despite such large differences, excellent agreement (to within +/- 20 per cent) exists between all the spectroscopically relevant line intensities. This provides confidence in the reliability of the calculations for plasma diagnostics. We have used the differences in the radiative and excitation rates amongst the three sets of calculations to obtain a measure of the uncertainty in each rate. Using a Monte Carlo approach, we have shown how these uncertainties affect the main theoretical ratios that are used to measure electron densities and temperatures.

Background and aims Modern agriculture is driving the release of excessive amounts of reactive nitrogen (N) from the soils to the environment, thereby threatening ecological balances and functions. The amendment of soils with biochar has been suggested as a promising solution to regulate the soil N cycle and reduce N effluxes. However, a comprehensive and quantitative understanding of biochar impacts on soil N cycle remains elusive. Methods A meta-analysis was conducted to assess the influence of biochar on different variables involved in soil N cycle using data compiled across 208 peer-reviewed studies. Results On average, biochar beneficially increases symbiotic biological N-2 fixation (63%), improves plant N uptake (11%), reduces soil N2O emissions (32%), and decreases soil N leaching (26%), but it poses a risk of increased soil NH3 volatilization (19%). Biochar-induced increase in soil NH3 volatilization commonly occurs in studies with soils of low buffering capacity (soil pH <=3D 5, organic carbon <=3D 10 g kg(-1), or clay texture), the application of high alkaline biochar (straw- or manure-derived biochar), or biochar at high application rate (> 40 t ha(-1)). Besides, if the pyrolytic syngas is not purified, the biochar production process may be a potential source of N2O and NOx emissions which correspond to 2-4% and 3-24% of the feedstock-N, respectively. Conclusions This study suggests that to make biochar beneficial for decreasing soil N effluxes, clean advanced pyrolysis technique and adapted use of biochar are of great importance.

By studying the N =3D 1 holographic minimal model at the critical level, we obtain the lowest N =3D 2 higher spin multiplet of spins in terms of two adjoint fermion types for generic N. We subsequently determine operator product expansions (between the lowest and second lowest (N =3D 2) higher spin multiplet of spins, and the corresponding Vasiliev's oscillator formalism with matrix generalization on AdS(3) higher spin theory in the extension of OSp(2|2) superconformal algebra. Under the large N limit (equivalent to large central charge) in the extension of N =3D 2 superconformal algebra in two dimensions, operator product expansions provide asymptotic symmetry algebra in AdS(3) higher spin theory.

We present a new and concise method for the preparation of asymmetrical N,N'-disubstituted guanidines starting from thiourea via the reaction of N-Boc-protected N'-alkyl/aryl substituted thioureas with an amine in the presence of mercury(II) chloride and triethylamine. (C) 2011 Elsevier Ltd. All rights reserved.

A versatile route to flexible ditopic ligands based on a 2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene scaffold, namely Williamson ether synthesis employing the 4,5-bis(chloromethyl) derivative of the xanthene and a phenol-substituted ligand donor, is demonstrated by the preparations of bis(terpyridine) xanthene L-1 and the bis(di(2-pyridylmethyl)amine)xanthene L-2 in good yields. The reaction of L-1 with [Pd(PhCN)(2) Cl-2] afforded the coordination complexes [L-1(PdCl)(2)][PF6](2) (4[PF6](2)) and [L-1(PdCl)][PF6] (5[PF6]). The Xray crystal structures of L-1 and 5[PF6]center dot solvate were determined and reveal intra-and intermolecular offset face-to-face stacking between terpyridine rings and intramolecular C-H center dot center dot center dot pi-phenyl ring interactions. Variable temperature H-1 NMR studies show temperature-dependent chemical shift changes suggestive for face-to-face interactions between the terpyridines in 4[PF6](2) and of 5[PF6] being sustained in solution. (C) 2013 Published by Elsevier B.V.

A new, simple method for the synthesis of N-(trifluoroacetyl)-protected sulfilimines from sulfides by a transition-metalfree, one-pot protocol is presented. The salient features of this process include the use of low-cost 1,3-dibromo-5,5-dimethylhydantoin, mild reaction conditions, and a broad substrate scope. The safety and robustness of the method has also been demonstrated by operations on a kilogram scale. In addition, a chiral resolution of a corresponding sulfoximine was achieved on a large scale.