Dinuclear Gold-Catalyzed para-Selective C-H Arylation of Undirected Arenes by Noncovalent Interactions.

The regioselectivity of C-H functionalization is commonly achieved by directing groups, electronic factors, or steric hindrance, which facilitate the identification of reaction sites. However, such strategies are less effective for reactants such as simple monofluoroarenes due to their relatively low reactivity and the modest steric demands of the fluorine atom. Herein, we present an undirected gold-catalyzed para-C-H arylation of a wide array of monofluoroarenes using air-stable aryl silanes and germanes at room temperature. A high para-regioselectivity (up to 98 : 2) can be realized by utilizing a dinuclear dppm(AuOTs)2 (dppm=bis(diphenylphosphino)methane) as the catalyst and hexafluorobenzene as the solvent. This provides a general and practical protocol for the concise construction of structurally diverse para-arylated monofluoroarenes through C-H activation manner. It features excellent functional group tolerance and a broad substrate scope (>80 examples). Besides, this strategy is also robust for other simple monosubstituted arenes and heteroarenes. Our mechanistic studies and theoretical calculations suggest that para-C-H selectivity arises from highly electrophilic and structurally flexible dinuclear Ar-Au(III)-Au(I) species, coupled with noncovalent interaction induced by hexafluorobenzene.

Decarboxylative C-H Alkylation of Heteroarene N-Oxides by Visible Light/Copper Catalysis.

This paper reports a highly site-selective alkylation of heteroarene N-oxides using hypervalent iodine(III) carboxylates to serve as an alkylating agent in the presence of a cheap copper catalyst under visible light conditions. This mild method proceeds at room temperature in an air atmosphere and can withstand various heteroarene N-oxides as well as various primary, secondary, and tertiary alkyl carboxylic acids. It also provides a practical method for enabling the rapid conversion of commercially available raw materials into medically relevant "drug-like" molecules.

An efficient method for the synthesis of 2-pyridones via C-H bond functionalization.

A simple and practical method to access N-substituted 2-pyridones via a formal [3+3] annulation of enaminones with acrylates based on RhIII-catalyzed C-H functionalization was developed. Control and deuterated experiments led to a plausible mechanism involving C-H bond cross-coupling and aminolysis cyclization. This strategy provides a short synthesis of structural motifs of N-substituted 2-pyridones.

α-Amino Acetal: A Synthetic Intermediate for the Construction of Aza-Polycycles.

One-step construction of aza-polycyclic skeletons was realized through double cyclization of the oxocarbenium and carbocation intermediates generated from α-amino acetals, which were designed and synthesized by employing our α-amination protocol of aldehydes. A simple process, a broad substrate range, commercialized materials, and extensive applications demonstrated the generality and effectiveness of this method.

[Trends of urban haze in Jiangsu Province China over the past 33 years].

Based on the surface meteorological data of Jiangsu Province during 1980-2012, climatic characteristics and trends of the weather phenomenon of haze were analyzed. The result indicates that during 1980-2012, the haze day increased, and the severe and moderate haze days significantly increased. In the northern and coastal cities, haze days had a significant increase. Haze is often appeared in the fall and winter, and is rare in the summer, it also occurs inland, and is less in the coast. The haze happens more frequently in June since the straw burning during.summer harvest time. The haze day was evenly distributed during the 80's, and increased during the 90's over southern and southwestern Jiangsu Province, middle and northern Jiangsu haze days had a growing after 2000, especially after 2010. The continuous, regional, and regional-continuous haze days were in an increasing trend. As the urban built-up area has been expanded each year, industrial emissions, coal consumption, and car ownership increase every year, resulting in regional temperature increase and relative humidity decrease, resulting in urban heat island and dry island effects. Thence the haze formation and maintenance conditions increased, which led to the increasing of haze days, and the continuous, regional and regional- continuous haze days were significantly increased.

Association of insulin gene variable number of tandem repeats regulatory polymorphism with polycystic ovary syndrome.

The present meta-analysis aimed to investigate the association between insulin gene variable number of tandem repeats (INS VNTR) and polycystic ovary syndrome (PCOS). Systematic searches of electronic databases, reference lists of included articles, and the abstracts presented at related scientific societies meetings were performed. Statistical analyses were conducted using software Stata 11.0. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were applied. Publication bias was tested by Begg's funnel plot and Egger's regression test. A total of 9 studies including 1075 PCOS patients and 2878 controls were included in the meta-analysis. There were evidence of statistical significant association between INS VNTR and PCOS in allelic model (OR=1.25, 95% CI=1.08-1.43, P=0.002) and dominant model (OR=1.34, 95% CI=1.11-1.63, P=0.003) but not in additive model (OR=1.38, 95% CI=0.93-2.04, P=0.11) and recessive model (OR=1.26, 95% CI=0.96-1.65, P=0.09). No significant publication bias was shown by funnel plots and Egger's regression tests. In conclusion, our meta-analysis suggests that the III allele of INS VNTR is associated with increased risk of PCOS.

[Microphysics of atmospheric aerosols during winter haze/fog events in Nanjing].

Intensive field observations of fog/haze events, including simultaneous measurements of aerosol particle and fog droplet size distributions, were conducted in Nanjing in November, 2007. Four weather conditions (fog, mist, wet haze and haze) were distinguished based on visibility and liquid water content firstly. Then, the microphysical characteristics of coarse and fine particles in each condition were investigated. The results showed the dominant sequence of the four weather conditions was haze<-->mist-->wet haze-->fog-->, wet haze-->mist<-->haze. The lasting time of pre-fog wet haze was longer than that of post-fog wet haze. The number, surface area and volume concentration of coarse particles with diameter larger than 2.0 micron in fog were much higher than those in the other three conditions, and the smallest concentrations were observed in haze. The size distributions of surface area and volume concentration exhibited multi-peak in fog droplets, while it showed single peak for coarse particles in haze, mist and wet haze. For the fine particles with diameter larger than 0.010 microm, the spectral shapes of surface area concentration are similar in fog (mist) and wet haze (haze) condition. The dominant size ranges of fine particle number concentration were in 0.04-0.13 microm and 0.02-0.14 microm for fog and wet haze, separately. The same dominant size ranges located in 0.02-0.06 microm for both mist and haze. During the transition processes from haze, mist and wet haze to fog, the concentration of smaller particles (less than 0.060-0.090 microm) reduced and vice versa for the corresponding larger particles. Temporal variation of aerosol number concentration correlated well with the root mean diameters negatively during the observation period. The number concentration of aerosol was the lowest and the mean diameter was the largest in fog periods.

[Luminescence properties of rare earth ions in 2SrO.0.84 P2O5.0.16 B2O3: RE3+ (RE=Ce, Tb)].

The phosphors of 2SrO.0.84 P2O5.0.16 B2O3: RE3+ (RE=Ce, Tb) were synthesized by high temperature solid state reaction. The luminescence properties of Ce3+, Tb3+ and the sensitization of Ce3+ to Tb3+ were studied. In the excitation spectrum of Ce3+, there are two broad bands at 232 and 296 nm respectively. Because of the large overlap between the emission bands, the authors could not separate them from each other. The authors could get two bands at 325 and 344 nm with the Gaussian fitting method. The possible reason is that these two peaks are from two light centers. In the phosphor of 2SrO.0.84 P2O5.0.16 B2O3: Tb3+, the excitation spectrum of Tb3+ exhibits high absorption at 370 nm and emission spectrum shows the strongest emission peak at 548 nm. The emission from the levels of (5)D3 and (5)D4 of Tb3+ appear at the same time, indicating that non-radiative process between them is inefficient. In the phosphor of Ce3+ and Tb3+ co-doped 2SrO.0.84 P2.O5.0.16 B2O3, efficient energy transfer exists.

[VUV spectral properties of (Y, Gd) Al3 (BO3)4: Tb].

(Y, Gd)A13 (BO3)4 doped with Ce and Tb were prepared by solid state reaction. The structure, VUV excitation properties, excitation were studied. (Y,Gd)Al3 (BO3)4 belongs to trigonal crystal system with thespace group of R32, and the crystal structure does not change as Tb3+ and Ce3+ ions are doped to the crystal lattice. The host absorption band of (Y,Gd)Al3 (BO3)4:Tb moves to longer wavelength as Gd3+ mol concentration increases. The energy transfer between Gd3+ and Tb3+ is very effective, and the samples with high Gd3+ mol concentrations have high radiant efficiencies. It was found that the luminescence of Tb3+ is quenched by Ce3+ in (Y,Gd)Al3(BO3)4:Ce, Tb under VUV excitation.

[Luminescence properties and spectral analysis of long phosphorescent phosphors: Ba(1 - x) Ca (x) Al2O4 : Eu2+, RE3+].

New long phosphorescent phosphors Ba(1 -x),Ca(x)Al2O4 : Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) with tunable color emission have been prepared by solid state reaction. The luminescence properties of the samples are discussed and analyzed. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is determined by x, under the excitation of UV. The wavelength of afterglow increases with increasing x until x equals 0.6, and when x equals 0.6, the luminescence property of Ba(1-x) Ca(x)Al2O4: Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) is similar to that of CaAl2O4 : Eu2+, RE3+. The XRD measurements were performed to investigate the single phase states of the samples, and it was found that the single phase limit in the phosphors is below an x value of 0.4. The thermoluminescence curves imply that the traps in the hosts are different with different x value, which well explains the varying delay time of the samples.

Distributed certification application via a trusted dealer.

Distributed certification via threshold cryptography is much more secure than other ways to protect certification authority (CA)'s private key, and can tolerate some intrusions. As the original system such as ITTC, etc., is unsafe, inefficient and impractical in actual network environment, this paper brings up a new distributed certification scheme, which although it generates key shares concentratively, it updates key shares distributedly, and so, avoids single-point failure like ITTC. It not only enhances robustness with Feldman verification and SSL protocol, but can also change the threshold (t, k) flexibly and robustly, and so, is much more practical. In this work, the authors implement the prototype system of the new scheme and test and analyze its performance.