Control of Elemental Distribution in the Nanoscale Solid-State Reaction That Produces (Ga1-xZnx)(N1-xOx) Nanocrystals

Solid-state chemical transformations at the nanoscale can be a powerful tool for achieving compositional complexity in nanomaterials. It is desirable to understand the mechanisms of such reactions and characterize the local-level composition of the resulting materials. Here, we examine how reaction temperature controls the elemental distribution in (Ga_1-xZn_x)(N_1-xO_x) nanocrystals (NCs) synthesized via the solid-state nitridation of a mixture of nanoscale ZnO and ZnGa₂O₄ NCs. (Ga_1-xZn_x)(N_1-xO_x) is a visible-light absorbing semiconductor that is of interest for applications in solar photochemistry. We couple elemental mapping using energy-dispersive X-ray spectroscopy in a scanning transmission electron microscope (STEM-EDS) with colocation analysis to study the elemental distribution and the degree of homogeneity in the (Ga_1-xZn_x)(N_1-xO_x) samples synthesized at temperatures ranging from 650 to 900 °C with varying ensemble compositions (i.e., x values). Over this range of temperatures, the elemental distribution ranges from highly heterogeneous at 650 °C, consisting of a mixture of larger particles with Ga and N enrichment near the surface and very small NCs, to uniform particles with evenly distributed constituent elements for most compositions at 800 °C and above. We propose a mechanism for the formation of the (Ga_1-xZn_x)(N_1-xO_x) NCs in the solid state that involves phase transformation of cubic spinel ZnGa₂O₄ to wurtzite (Ga_1-xZn_x)(N_1-xO_x) and diffusion of the elements along with nitrogen incorporation. The temperature-dependence of nitrogen incorporation, bulk diffusion, and vacancy-assisted diffusion processes determines the elemental distribution at each synthesis temperature. Finally, we discuss how the visible band gap of (Ga_1-xZn_x)(N_1-xO_x) NCs varies with composition and elemental distribution.

[The role of smoking and metabolic enzyme polymorphisms in the organic solvent induced chronic encephalopathy]

OBJECTIVE

The organic solvents and other exogenous compounds of metabolic enzymes genetic variation may affect the risk of the toxic effect of organic solvents exposure. Therefore, this research we observed the glutathione transferase M1 and T1 (GSTM1, GSTT1) deletion mutation genotype, two kinds of microsomal epoxide hydrolase (mEPHX) genetic polymorphism, organic solvents exposure and smoking effection in chronic cases of toxic encephalopathy (CTE) correlation.

METHODS

The object was 115 patients who had a long history of organic solvents exposure, were divieded into two groups: CTE (n=83) , no CET (n=32) according to clinical diagnosis. DNA was isolated from patients in white blood cells through the multiple-polymerase chain reaction to determine the loss of GSTM1 and GSTT1 genotype. two kinds of mEPHX polymorphism were analysised through the PCR-RFLP (restriction fragment length polymorphism).

RESULTS

The relative risk has obviously improved when lack of GSTM1 genotypes to CTE (RR=2.35, 95% CI 2.35 0.96). in according to the patient's Smoking condition and classify genotype, patients lack of GSTM1 genotypes had a significantly higher risk CTE than GSTM1+genotype patients (RR=3.13, 95% CI 3.13 1.2) , both mEPHX polymorphisms had nothing to do with an increased risk of CTE.

CONCLUSION

The GSTM1 genotypes played an important role in the organic solvent induced the CTE of susceptibility.it was Influenced by the interaction between smoking at the same time.

First Report of Barley yellow striate mosaic virus on Wheat in China

In the spring of 2014, a survey of viral diseases on wheat (Triticum aestivum L.) was carried out in Hebei Province, China. The samples with virus-like symptoms of dwarfing and flag leaf yellowing were collected in Zhaoxian, Quyang, Anxin, and Luannan. To reproduce the viral symptoms and confirm whether the unknown virus was transmitted by insect vectors, the nymphs of aviruliferous planthopper (Laodelphax striatellus Fallen, Homoptera: Delphacidae) were transferred onto diseased wheat from the field for a 3-day acquisition access period and a 10-day incubation on fresh wheat seedlings, and then were exposed to 2- to 3-leaf stage wheat seedlings of wheat variety Shixin828 for a 3-day inoculation access period. The infected wheat plants developed mosaic symptoms on the young leaves at 7 days post inoculation (dpi), and followed with severe symptoms including stunting, chlorotic spots, and striation along the veins of leaves at around 14 dpi. The infection symptoms were same as in the field but distinct from wheat infected with Rice black streaked dwarf virus (RBSDV) or Northern cereal mosaic virus (NCMV). For further confirmation, total RNA was extracted from the symptomatic wheat leaves, and NCMV specific primers, NCMV-PF/NCMV-PR (5'-ATGGATAAGAAAGCAAGTGGA-3'/5'-TTAAAAGTCGGCATACGGGTC-3') and RBSDV specific primers, S10-F/S10-R (5'-TTACCCAACATCACGCAACT-3'/5'-GAGCAGGAACTTCACGACAAC-3') were used for amplification of sequences of phosphoprotein and coat protein genes, respectively. Neither RBSDV nor NCMV were present in the symptomatic tissue according to the RT-PCR assay (4). Tissues derived from symptomatic wheat leaves were fixed and embedded in Spurr's resin and used for ultra-thin sectioning and transmission electron microscopy observations, revealing large amounts of Rhabdovirus-like particles in the cytoplasm. The identified particles were about 315 to 353 × 46 to 57 nm, similar in size to Barley yellow striate mosaic virus (BYSMV), a member of the genus Cytorhabdovirus reported from Italy (2). The specific primer pair (5'-ACTAAGGGGGTACTCCGACC-3' and 5'-CTGATCTGCTTTGAGGGGCA-3') was designed based on the reported polymerase (L) gene sequence of BYSMV isolate Zanjan-1 (GenBank Accession No. FJ665628) (1), and used for the BYSMV detection by RT-PCR. A single bright band of the expected size (~500 bp) was obtained from total RNA extracted from the plants exhibiting symptoms in the greenhouse. No such band was amplified from asymptomatic plants, while 15 out of 23 field samples also produced the same 500-bp products in RT-PCR. PCR products from three virus-positive field samples were sequenced directly and the sequences were submitted to GenBank (KM052176, KM052177, and KM052178). BLAST search showed that the sequences shared 96 to 97% nucleotide identity with the polymerase L gene sequence of BYSMV isolate Zanjan-1, whereas only 73 to 75% identity with NCMV (AB030277 and GU985153) (1,3,5). To our knowledge, this is the first report of BYSMV occurrence on wheat in China. References: (1) R. Almasi et al. J. Phytopathol. 158:351, 2010. (2) A. Appiano et al. Cytol. 6:105, 1974. (3) H. C. Chen et al. Sci. Agric. Sinica 3:64, 1980. (4) X. F. Duan et al. Acta Phytopathol. Sinica 40:337, 2010. (5) F. Tanno et al. Arch. Virol. 145:1373, 2000.

Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles

The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer.

Local boron environment in B-doped nanocrystalline diamond films

Thin films of heavily B-doped nanocrystalline diamond (B:NCD) have been investigated by a combination of high resolution annular dark field scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy performed on a state-of-the-art aberration corrected instrument to determine the B concentration, distribution and the local B environment. Concentrations of ~1 to 3 at.% of boron are found to be embedded within individual grains. Even though most NCD grains are surrounded by a thin amorphous shell, elemental mapping of the B and C signal shows no preferential embedding of B in these amorphous shells or in grain boundaries between the NCD grains, in contrast with earlier work on more macroscopic superconducting polycrystalline B-doped diamond films. Detailed inspection of the fine structure of the boron K-edge and comparison with density functional theory calculated fine structure energy-loss near-edge structure signatures confirms that the B atoms present in the diamond grains are substitutional atoms embedded tetrahedrally into the diamond lattice.

Identification of neutral genes at pollen sterility loci Sd and Se of cultivated rice (Oryza sativa) with wild rice (O. rufipogon) origin

Pollen sterility is one of the main hindrances against the utilization of strong intersubspecific (indica-japonica) heterosis in rice. We looked for neutral alleles at known pollen sterility loci Sd and Se that could overcome this pollen sterility characteristic. Taichung 65, a typical japonica cultivar, and its near isogenic lines E7 and E8 for pollen sterility loci Sd and Se were employed as tester lines for crossing with 13 accessions of wild rice (O. rufipogon). Pollen fertility and genotypic segregations of the molecular markers tightly linked with Sd and Se loci were analyzed in the paired F(1)s and F(2) populations. One accession of wild rice (GZW054) had high pollen fertility in the paired F(1)s between Taichung 65 and E7 or E8. Genotypic segregations of the molecular markers tightly linked with Sd and Se loci fit the expected Mendelian ratio (1:2:1), and non-significances were shown among the mean pollen fertilities with the maternal, parental, and heterozygous genotypes of each molecular markers tightly linked with Sd and Se loci. Evidentially, it indicated that the alleles of Sd and Se loci for GZW054 did not interact with those of Taichung 65 and its near isogenic lines, and, thus were identified as neutral alleles Sd(n) and Se(n). These neutral genes could become important germplasm resources for overcoming pollen sterility in indica-japonica hybrids, making utilization of strong heterosis in such hybrids viable.

[Molecular mapping of the S-a locus for F1 pollen sterility in cultivated rice (Oryza sativa L.)]

F1 pollen sterility in cultivated rice (Oryza sativa L.) was found to be caused by at least six loci of F1 pollen sterility genes. At the S-a locus, one of the six loci for F1 pollen sterility, the allelic interaction of S-ai and S-aj causes the male gametes carrying S-aj allele abortive. To map the S-a locus, Taichung 65(T65), a Keng (japonica) variety with S-aj/S-aj, its isogenic F1 sterile line TISL4 with S-ai/S-ai from Chin-tsao, a Hsien (indica) variety, and the F2 population from cross T65 x TISL4 were used as materials. The polymorphism between T65 and TISL4 detected by RFLP and RAPD analysis was less than 1%. This result indicated that short segments from Chin-tsao were introgressed into the isogenic F1 sterile line, since the TISL4 was developed by repeatedly backcrossing for thirteen times. By linkage analysis of S-a and the marker loci, the S-a locus was mapped on chromosome 1. The genetic distances between S-a and RFLP markers CDO548 and RG146 are 6.4 cM and 7.2 cM respectively, and those between S-a and RAPD markers O11-1000 and Y13-500 are 6.8 cM and 11.2 cM respectively. The mapping of the S-a locus is an important step towards marker-aided selection for overcoming the hybrid sterility in rice.

Human hepatocellular carcinoma cell lines exhibit multidrug resistance unrelated to MRD1 gene expression

Multidrug resistance of human cancer cells may result from expression of P-glycoprotein, the product of the MRD1 gene, acting as an energy-dependent drug efflux pump. However, direct evidence that expression of the MDR1 gene contributes to the multidrug resistance of human liver carcinomas has not been established. In this study, we tested five cell lines derived from human hepatocellular carcinomas for sensitivity to a variety of drugs used widely as anticancer agents; these included vinblastine, doxorubicin, actinomycin D, mitomycin C, 5-fluorouracil, 6-mercaptopurine, melphalan, methotrexate, cis-platinum and etoposide (VP-16). All five hepatoma cell lines were resistant at different levels to these chemicals compared to human KB cells. Although it has been demonstrated that resistance to vinblastine, colchicine, doxorubicin and actinomycin D in human multidrug-resistant cells is associated with overexpression of P-glycoprotein, very little expression of P-glycoprotein was found in these human hepatoma cells. Neither verapamil nor quinidine, inhibitors of the drug efflux pump, were able to overcome multidrug resistance in hepatoma cells. These results indicate that the multidrug resistance phenotype in human hepatocellular carcinoma cells cannot be attributed to expression of the MDR1 gene, but that novel mechanisms may account for the resistance of these cancer cells.