Use of portable X-ray fluorescence spectroscopy and geostatistics for health risk assessment.

Laboratory analysis of trace metals using inductively coupled plasma (ICP) spectroscopy is not cost effective, and the complex spatial distribution of soil trace metals makes their spatial analysis and prediction problematic. Thus, for the health risk assessment of exposure to trace metals in soils, portable X-ray fluorescence (PXRF) spectroscopy was used to replace ICP spectroscopy for metal analysis, and robust geostatistical methods were used to identify spatial outliers in trace metal concentrations and to map trace metal distributions. A case study was carried out around an industrial area in Nanjing, China. The results showed that PXRF spectroscopy provided results for trace metal (Cu, Ni, Pb and Zn) levels comparable to ICP spectroscopy. The results of the health risk assessment showed that Ni posed a higher non-carcinogenic risk than Cu, Pb and Zn, indicating a higher priority of concern than the other elements. Sampling locations associated with adverse health effects were identified as 'hotspots', and high-risk areas were delineated from risk maps. These 'hotspots' and high-risk areas were in close proximity to and downwind from petrochemical plants, indicating the dominant role of industrial activities as the major sources of trace metals in soils. The approach used in this study could be adopted as a cost-effective methodology for screening 'hotspots' and priority areas of concern for cost-efficient health risk management.

Reference gene selection for qRT-PCR analyses of luffa (Luffa cylindrica) plants under abiotic stress conditions.

Selecting suitable internal reference genes is an important prerequisite for the application of quantitative real-time PCR (qRT-PCR). However, no systematic studies have been conducted on reference genes in luffa. In this study, seven reference genes were selected, and their expression levels in luffa plants exposed to various simulated abiotic stresses [i.e., cold, drought, heat, salt, H2O2, and abscisic acid (ABA) treatments] were analyzed by qRT-PCR. The stability of the reference gene expression levels was validated using the geNorm, NormFinder, BestKeeper, and RefFinder algorithms. The results indicated that EF-1α was the most stably expressed and suitable reference gene overall and for the heat, cold, and ABA treatments. Additionally, UBQ expression was stable following the salt treatment, whereas TUB was identified as a suitable reference gene for H2O2 and drought treatments. The reliability of the selected reference genes was verified by analyzing the expression of copper/zinc superoxide dismutase (Cu/Zn-SOD) gene in luffa. When the most unstable reference genes were used for data normalizations, the resulting expression patterns had obvious biases when compared with the expression patterns for the most ideal reference genes used alone or combined. These results will be conducive to more accurate quantification of gene expression levels in luffa.

9-Ethyl-3-(2-methyl-benzo-yl)-9H-carbazole.

In the title compound, C(22)H(19)NO, the dihedral angle between the benzene ring and the carbazole ring system 77.1 (1)°.. The crystal structure is stabilized by inter-molecular aromatic π-π inter-actions between the benzene ring and the pyrrole ring of the carbazole system of neighbouring mol-ecules [centroid-centroid distance = 3.617 (4) Å]. In addition, the crystal structure exhibits a weak inter-molecular C-H⋯π inter-action.

1-[9-Ethyl-6-(2-methyl-benzo-yl)-9H-carbazol-3-yl]ethanone.

In the title compound, C(24)H(21)NO(2), the pendant benzene ring is inclined at a dihedral angle of 86.66 (18)° with respect to the adjacent aromatic ring of the carbozole unit. In the crystal structure, symmetry-related mol-ecules are linked via C-H⋯O and C-H⋯π inter-actions.

[Characteristics and Sources of Water-soluble Organic Carbon/Nitrogen in PM2.5 During Spring in Changzhou].

To understand the characteristics and sources of water-soluble organic carbon (WSOC) and organic nitrogen (WSON) in atmospheric aerosols during spring in Changzhou, 84 fine particle (PM2.5) samples were collected from March 1 to May 30, 2017, in Changzhou. The water-soluble components, including water-soluble organic carbon, water-soluble total nitrogen (WSTN), water-soluble ions, and carbonaceous components (OC and EC), were analyzed. The levels of WSOC and WSON and their source characteristics were discussed. The results show that the average concentrations of PM2.5, WSOC, and WSON are 101.97, 7.63, and 1.50 µg·m-3, respectively, during the sampling period. The WSON accounts for 12.9% of the WSTN and the water-soluble inorganic nitrogen mainly exists in two forms, that is, NH4+ and NO3-, accounting for 86.15% of the WSTN. The WSOC is weakly correlated with WSON (r=0.58), indicating that WSOC and WSON do not have the same sources. The WSOC is related to SOC, K+, and secondary ions (SO42-, NH4+, and NO3-), indicating that it is mainly derived from biomass burning and secondary conversion; WSON is strongly correlated to secondary ions, indicating that it is mainly derived from secondary conversion. The wind speed is the main factor affecting the WSOC and WSON concentration levels. Furthermore, the WSON is positively correlated with the air pressure and negatively correlated with the temperature. The results of the principal component analysis show that PM2.5 mainly originates from four sources:secondary formation, dust, coal combustion, biomass burning, and the ocean. The backward trajectory analysis indicates that the total concentrations of PM2.5, WSOC, and WSON in air masses from long-distance transformation are higher than that from short-distance transmission, whereas there is no significant difference in the WSON/WSTN ratio from different transmission paths.

4-Sulfocalix[4]arene/Cucurbit[7]uril-Based Supramolecular Assemblies through the Outer Surface Interactions of Cucurbit[n]uril.

Upon mixing of aqueous solutions of the freely soluble building blocks cucurbit[7]uril (Q[7]) and 4-sulfocalix[4]arene (SC[4]A), white microcrystals instantly separate in near-quantitative yield. The driving force for this assembly is suggested to be the outer-surface interaction of the Q[n]. Dynamic light scattering, scanning electron microscopy, and NMR (diffusion-ordered NMR spectroscopy) analyses have confirmed the supramolecular aggregation of Q[7] and SC[4]A. Titration 1H NMR spectroscopy and isothermal titration calorimetry have shown that the interaction ratio of Q[7] and SC[4]A is close to 3:1. Moreover, the Q[7]/SC[4]A-based supramolecular assembly can accommodate molecules of some volatile compounds or luminescent dyes. Thus, this work offers a simple and highly efficient means of preparing adsorbent or solid fluorescent materials.

Architectures and DFT calculations of polyrotaxane MOFs with nanoscale macrocycles.

Polyrotaxane metal-organic frameworks (PMOFs) have attracted considerable attention due to their aesthetic topologies and potential biological applications. In this paper, we synthesized two kinds of hcb networks with nanoscale macrocycles. The hcb networks interlocked with each other in inclined and parallel interlocking modes respectively, giving rise to two new PMOFs, {[Ni(DPDBT)(bdc)]·(H2O)2}n (1) and {[Zn(DPDBT)(fuma)]}n (2). DFT calculations are used to elucidate why the inclined interlocking mode is preferential for 1 while the parallel interlocking mode is preferential for 2. The networks of 1 with a parallel interlocking mode, as well as 2 with an inclined interlocking mode, were simulated. The total energies of the parallel and inclined structures proved that the as-synthesized interlocking modes of 1and 2 are more stable. Moreover, photophysical properties and thermal analyses of related ligands and complexes are investigated and discussed in detail.

[Seasonal Variation Characteristics and Potential Source Contribution of Sulfate, Nitrate and Ammonium in Beijing by Using Single Particle Aerosol Mass Spectrometry].

Single particle aerosol mass spectrometry (SPAMS) was deployed to continuously observe the aerosol particles of Beijing urban area from 2013-12 to 2014-11, and the hourly average data of sulfate, nitrate and ammonium (SNA) were obtained using the characteristic ion tracer method. The mixing state and size distribution of SNA were analyzed. In addition, based on Hysplit 48 h back air mass trajectory results in combination with Concentration Weighted Trajectory method (CWT), we obtained the seasonal potential source contribution area of SNA. The results showed that the mixture of sulfate, nitrate and ammonium in spring and summer was more stable than that in autumn and winter. The size distribution of sulfate and nitrate was very similar. The size distribution characteristics of SNA followed the order of autumn > summer > spring > winter. The potential source region of SNA had similar spatial distribution characteristics, and the potential source region of SNA was mainly located in Beijing and south areas, especially at Tianjin, Langfang, Hengshui, Baoding and Shijiazhuang.

Muscular forces exerted on the normal deciduous dentition.

This study evaluated the distributing characteristic of the forces exerting on the normal deciduous dentition and the relationship between the muscular forces, sex, and oral function. The pressure measurements were made with a computer-aided perioral force-measuring system designed by the authors. The forces were measured when the subject's head position was in a state of natural head position and oral function was at rest or with swallowing. The results indicated that the forces from lips, cheeks, and tongue at rest were about 37-208 N/m2, whereas the pressure during swallowing was about 1009-1679 N/m2. At rest, the pressure from lips and cheeks was higher than that from tongue (P < .05), whereas during swallowing, the lingual pressure was statistically larger (P < .001). A significant correlation existed between the muscular pressure and sex. When at rest, the boy's force from cheeks was higher than that of the girl's (P < .05) but during swallowing the boy's labial pressure was statistically higher than that of the girl's (P < .01). It was concluded that (1) the deciduous teeth are not in a state of absolute balance between external and internal forces, (2) the distributing manner and unbalanced mode of the forces are different with the different oral functions, (3) the lingual side of the mandibular anterior teeth endures great differences during oral functions and it may account for high incidence of malocclusion in this segment, and (4) a statistical difference between muscular forces and sex exists.

Chiral crystallization and optical properties of three metal complexes based on two non-centrosymmetric tripodal ligands.

Chiral coordination polymers have attracted much attention due to their special properties and significant applications. In this work, we synthesized two non-centrosymmetric ligands, N,N-bis(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)aniline (DIMPPA) and N-(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)-N-(4-(pyridin-4-yl)phenyl)aniline (MIDPPA), via structural modification of two reported centrosymmetric ligands; after that achiral → chiral induction occurred in the construction of three coordination polymers namely {[Cd(DIMPPA)(5-OH-bdc)](H2O)}n (1), {[Co(DIMPPA)(5-OH-bdc)](H2O)}n (2) and {[Cd2(MIDPPA)2(D-ca)2(H2O)2](H2O)5}n (3), when replacing the reported centrosymmetric ligands with non-centrosymmetric ligands (5-OH-H2bdc = 5-hydroxyisophthalic acid, D-H2ca = D-camphoric acid). Isostructural complexes 1 and 2 exhibit chiral 2D → 3D frameworks with the coexistence of polyrotaxane and parallel polycatenation features. Complex 3 shows two-fold interpenetrating 3D chiral architecture with cds-type topology. The luminescence emissions of both complexes 1 and 3 are mostly assignable to the internal π→π* electron transition in DIMPPA and MIDPPA, respectively. Complex 3 can satisfy the fundamental requirement of second-order nonlinear optical materials.