Density Functional Theory Study of 12mer Single-Strand Guanine Oligomer and Associated Muon Hyperfine Interaction.

Density functional theory method at the B3LYP/6-31G level was used to determine the structure of 12mer single-strand guanine oligomers. The length and width of the optimized structure are 38.7 and 18.2 Å, respectively, and the observed high-resolution transmission electron microscopy image of the 12mer single-strand guanine sample shows similar oligomer dimensions with the calculated ones. Both HOMO and LUMO are significantly delocalized, and the calculated HOMO-LUMO gap is 3.31 eV. A total of 96 muonium trapping sites at C2, C4, C5, C6, C8, N3, N7, and O6 were investigated. All 12 C8 sites have lower energy than the other 84 sites and are clustered in the energy-muon hyperfine coupling constant scatter plot. The calculated muon hyperfine coupling constant at C8 sites range from 384.6 to 481.1 MHz, and the corresponding estimated ALC-µSR resonance for |ΔM| = 1 range from 1.419 to 1.775 T.

Density Functional Theory Studies of the Electronic Structure and Muon Hyperfine Interaction in [Au25(SR)18]0 and [Au25(SeR)18]0 Nanoclusters.

Density functional theory computational investigation was performed to study the electronic structures, muon sites, and the associated hyperfine interactions in [Au25(SR)18]0 and [Au25(SeR)18]0 where R is phenylethane. The calculated electronic structures show inhomogeneous spin density distribution and are also affected by different ligands. The two most stable muon sites near Au atoms in the thiolated system are MAu11 and MAu6. When the thiolate ligands were replaced by selenolate ligands, the lowest energy positions of muons moved to MAu6 and MAu5. Muons prefer to stop inside the Au12 icosahedral shell, away from the central Au and the staple motifs region. Muonium states at phenyl ring and S/Se atoms in the ligand were found to be stable and the Fermi contact fields are much larger as compared to the field experienced by muons near Au atoms.

Diffusion Tensor Imaging of White Matter in Children Born from Preeclamptic Gestations.

BACKGROUND AND PURPOSE: Individuals born from pregnancies complicated by preeclampsia have an elevated risk for cognitive impairment. Deviations in maternal plasma angiokines occur for prolonged intervals before clinical signs of preeclampsia. We hypothesized that fetal brain vascular and nervous tissue development become deviated during maternal progression toward preeclampsia and that such deviations would be detectable by MR imaging. MATERIALS AND METHODS: In this pilot study, 10 matched (gestational and current ages) pairs (5 boys/5 girls, 7-10 years of age) from preeclampsia or control pregnancies were examined by using diffusion tensor MR imaging. An unbiased voxel-based analysis was conducted on fractional anisotropy and mean diffusivity parametric maps. Six brain ROIs were identified for subsequent analysis by tractography (middle occipital gyrus, caudate nucleus and precuneus, cerebellum, superior longitudinal fasciculus, and cingulate gyrus). RESULTS: Statistical differences were present between groups for fractional anisotropy in the caudate nucleus (offspring from preeclamptic gestation > controls), volume of the tract for the superior longitudinal fasciculus (offspring from preeclamptic gestation > controls) and the caudate nucleus (offspring from preeclamptic gestation > controls), and for parallel diffusivity of the cingulate gyrus (offspring from preeclamptic gestation > controls). CONCLUSIONS: These novel preliminary results along with previous results from the same children that identified altered cerebral vessel calibers and increased regional brain volumes justify fully powered MR imaging studies to address the impact of preeclampsia on human fetal brain development.

Resistance to Fusarium head blight and seedling blight in wheat is associated with activation of a cytochrome p450 gene.

ABSTRACT One plant genotype displays a resistance phenotype at one development stage but a susceptible reaction to the same pathogen at another stage, which is referred to here as resistance inversion. In wheat, Fusarium head blight (FHB)-resistant cv. Sumai3 showed a Fusarium seedling blight (FSB)-susceptible reaction whereas FHB-susceptible cv. Annong8455 exhibited FSB resistance when challenged with a Fusarium asiaticum strain that produces deoxynivalenol (DON). The resistance to FHB and FSB in wheat was closely associated with expression of a plant cytochrome P450 gene in response to FHB pathogens and mycotoxins. Quantitative real-time polymerase chain reaction analyses showed that expression of nine defense-related genes in spikes and seedlings was induced by the fungal infection, in which a massive accumulation of a plant cytochrome P450 gene, CYP709C1, was clearly associated with the resistance reaction in both seedling and spike. The FHB-resistant Sumai3 accumulated 7-fold more P450 transcripts than did the FHB-susceptible Annong8455, while 84-fold more P450 transcripts were accumulated in the FSB-resistant Annong8455 than the FSB-susceptible Sumai3. A Fusarium strain with a disrupted Tri5 gene, which is not able to produce the first enzyme essential for trichothecene mycotoxin biosynthesis, also induced more P450 transcripts in FHB- and FSB-resistant cultivars. The fungal activation of the P450 gene was more profound in the FSB-resistant reaction than the FHB-resistant reaction relative to their susceptible counterparts. DON triggered a differential expression of the P450 gene with comparable patterns in spikes and seedlings in a resistance-dependent manner. These results may provide a basis for dissecting mechanisms underlying FHB and FSB resistance reactions in wheat and revealing functions of the cytochrome P450 in plant detoxification and defense.

Replica multichannel polymer chips with a network of sacrificial channels sealed by adhesive printing method.

Replica microchips for capillary array electrophoresis containing 10 separation channels (50 microm width, 50 microm depth and 100 microm pitch) and a network of sacrificial channels (100 microm width and 50 microm depth) were successfully fabricated on a poly(methyl methacrylate) (PMMA) substrate by injection molding. The strategy involved development of moving mask deep X-ray lithography to fabricate an array of channels with inclined channel sidewalls. A slight inclination of channel sidewalls, which can not be fabricated by conventional deep X-ray lithography, is highly required to ensure the release of replicated polymer chips from a mold. Moreover, the sealing of molded PMMA multichannel chips with a PMMA cover film was achieved by a novel bonding technique involving adhesive printing and a network of sacrificial channels. An adhesive printing process enables us to precisely control the thickness of an adhesive layer, and a network of sacrificial channels makes it possible to remove air bubbles and an excess adhesive, which are crucial to achieving perfect sealing of replica PMMA chips with well-defined channel and injection structures. A CCD camera equipped with an image intensifier was used to simultaneously monitor electrophoretic separations in ten micro-channels with laser-induced fluorescence detection. High-speed and high-throughput separations of a 100 bp DNA ladder and phi X174 Hae III DNA restriction fragments have been demonstrated using a 10-channel PMMA chip. The current work establishes the feasibility of mass production of PMMA multichannel chips at a cost-effective basis.