Adsorption mechanism of different toxic gases onto pristine BNC2 and Al-doped BNC2 monolayers.

Graphene-based ternary BNC materials have been widely explored for the fabrication of gas sensors because of their various two-dimensional conjugated structures, high conductivity and large specific surface areas. To understand the essential physics and gas sensing properties, we focus on a sheet with equal concentration of C and BN, i.e. a BNC2 sheet. Using density functional theory, we have explored the effects of doping of an aluminium (Al) atom on the structural and electronic properties of a ternary BNC monolayer. We have studied the adsorption mechanism of various gas molecules such as CO, CO2, NO, NO2, SO2, and SO3 on BNC2 and Al@BNC2 MLs. Doping of the Al atom in BNC2 changes the structural as well as electronic properties of the host dramatically. The large-sized Al atom protrudes out from the BNC2 ML. The induced defects due to doping of the Al atom in BNC2 reduce the band gap of the BNC2 ML and enhance the reactivity of the BNC2 ML. The adsorption of CO, CO2, NO, NO2, SO2, and SO3 gas molecules shows higher interaction towards the Al@BNC2 ML as compared to the BNC2 ML. Among all the gas molecules, the maximum interaction of NO2 gas molecules is found with the Al@BNC2 ML. Adsorbed gas molecules act as charge acceptors from both the MLs. The improved conductivity of the Al@BNC2 ML as compared to BNC2 with the adsorption of gas molecules offers the basis for the development of ternary BNC-based gas sensors.

Differences in activation of intracellular signaling in primary human retinal endothelial cells between isoforms of VEGFA 165.

Purpose: There are reports that a b-isoform of vascular endothelial growth factor-A 165 (VEGFA165b) is predominant in normal human vitreous, switching to the a-isoform (VEGFA165a) in the vitreous of some diseased eyes. Although these isoforms appear to have a different ability to activate the VEGF receptor 2 (VEGFR2) in various endothelial cells, the nature of their ability to activate intracellular signaling pathways is not fully characterized, especially in retinal endothelial cells. We determined their activation potential for two key intracellular signaling pathways (MAPK, AKT) over complete dose-response curves and compared potential effects on the expression of several VEGFA165 target genes in primary human retinal microvascular endothelial cells (HRMECs). Methods: To determine full dose-response curves for the activation of MAPK (ERK1/2), AKT, and VEGFR2, direct in-cell western assays were developed using primary HRMECs. Potential differences in dose-response effects on gene expression markers related to endothelial cell and leukocyte adhesion (ICAM1, VCAM1, and SELE) and tight junctions (CLDN5 and OCLN) were tested with quantitative PCR. Results: Activation dose-response analysis revealed much stronger activation of MAPK, AKT, and VEGFR2 by the a-isoform at lower doses. MAPK activation in primary HRMECs displayed a sigmoidal dose-response to a range of VEGFA 165 a concentrations spanning 10-250 pM, which shifted higher into the 100-5,000 pM range with VEGFA 165 b. Similar maximum activation of MAPK was achieved by both isoforms at high concentrations. Maximum activation of AKT by VEGFA 165 b was only half of the maximum activation from VEGFA 165 a. At a lower intermediate dose, where VEGFA 165 a activated intracellular signaling stronger than VEGFA 165 b, the changes in VEGFA target gene expression were generally greater with VEGFA 165 a. Conclusions: In primary HRMECs, VEGFA 165 a could maximally activate MAPK and AKT at lower concentrations where VEGFA 165 b had relatively little effect. The timing for maximum activation of MAPK was similar for the isoforms, which is different from that reported for non-retinal endothelial cells. Although differences in VEGFA 165 a and VEGFA 165 b are limited to the sequence of their six C-terminal six amino acids, this results in a large difference in their ability to activate at least two key intracellular signaling pathways and VEGF-target gene expression in primary human retinal endothelial cells.

Norrin treatment improves ganglion cell survival in an oxygen-induced retinopathy model of retinal ischemia.

Treatment of a mouse model of oxygen-induced retinopathy (OIR) with recombinant human Norrin (Norrie Disease Protein, gene: NDP) accelerates regrowth of the microvasculature into central ischemic regions of the neural retina, which are generated after treatment with 75% oxygen. While this reduces the average duration and severity of ischemia overall, we do not know if this accelerated recovery of the microvasculature results in any significant survival of retinal ganglion cells (RGCs). The purpose of this study was to investigate ganglion cell survival with and without the intravitreal injection of Norrin in the murine model of oxygen induced retinopathy (OIR), using two strains of mice: C57BL/6J and Thy1-YFP mice. Intravitreal injections of Norrin or vehicle were done after five days of exposure to 75% oxygen from ages P7 to P12. The C57BL/J mice were followed by Spectral-Domain Optical Coherence Tomography (SD-OCT), and the average nerve fiber layer (NFL) and inner-plexiform layer (IPL) thicknesses were measured at twenty-four locations per retina at P42. Additionally, some C57BL/J retinas were flat mounted and immunostained for the RGC marker, Brn3a, to compare the population density of surviving retinal ganglion cells. Using homozygous Thy1-YFP mice, single intrinsically fluorescent RGCs were imaged in live animals with a Micron-III imaging system at ages P21, 28 and P42. The relative percentage of YFP-fluorescent RGCs with dendritic arbors were compared. At age P42, the NFL was thicker in Norrin-injected OIR eyes, 14.4 µm, compared to Vehicle-injected OIR eyes, 13.3 µm (p = 0.01). In the superior retina, the average thickness of the IPL was greater in Norrin-injected OIR eyes, 37.7 µm, compared to Vehicle-injected OIR eyes, 34.6 µm (p = 0.04). Retinas from Norrin injected OIR mice had significantly more surviving RGCs (p = 0.03) than vehicle-injected mice. Based upon NFL thickness and counts of RGCs, we conclude that Norrin treatment, early in the ischemic phase, increased the relative population density of surviving RGCs in the central retinas of OIR mice.

Sensing Characteristics of a Graphene-like Boron Carbide Monolayer towards Selected Toxic Gases.

By using first-principles calculations based on density functional theory, we study the adsorption efficiency of a BC3 sheet for various gases, such as CO, CO2, NO, NO2, and NH3. The optimal adsorption position and orientation of these gas molecules on the BC3 surface is determined and the adsorption energies are calculated. Among the gas molecules, CO2 is predicted to be weakly adsorbed on the graphene-like BC3 sheet, whereas the NH3 gas molecule shows a strong interaction with the BC3 sheet. The charge transfer between the molecules and the sheet is discussed in terms of Bader charge analysis and density of states. The calculated work function of BC3 in the presence of CO, CO2, and NO is greater than that of a bare BC3 sheet. The decrease in the work function of BC3 sheets in the presence of NO2 and NH3 further explains the affinity of the sheet towards the gas molecules. The energy gap of the BC3 sheets is sensitive to the adsorption of the gas molecules, which implies possible future applications in gas sensors.

Different effects of valproic acid on photoreceptor loss in Rd1 and Rd10 retinal degeneration mice.

PURPOSE: The histone-deacetylase inhibitor activity of valproic acid (VPA) was discovered after VPA's adoption as an anticonvulsant. This generated speculation for VPA's potential to increase the expression of neuroprotective genes. Clinical trials for retinitis pigmentosa (RP) are currently active, testing VPA's potential to reduce photoreceptor loss; however, we lack information regarding the effects of VPA on available mammalian models of retinal degeneration, nor do we know if retinal gene expression is perturbed by VPA in a predictable way. Thus, we examined the effects of systemic VPA on neurotrophic factor and Nrl-related gene expression in the mouse retina and compared VPA's effects on the rate of photoreceptor loss in two strains of mice, Pde6b(rd1/rd1) and Pde6b(rd10/rd10) . METHODS: The expression of Bdnf, Gdnf, Cntf, and Fgf2 was measured by quantitative PCR after single and multiple doses of VPA (intraperitoneal) in wild-type and Pde6b(rd1/rd1) mice. Pde6b(rd1/rd1) mice were treated with daily doses of VPA during the period of rapid photoreceptor loss. Pde6b(rd10/rd10) mice were also treated with systemic VPA to compare in a partial loss-of-function model. Retinal morphology was assessed by virtual microscopy or spectral-domain optical coherence tomography (SD-OCT). Full-field and focal electroretinography (ERG) analysis were employed with Pde6b(rd10/rd10) mice to measure retinal function. RESULTS: In wild-type postnatal mice, a single VPA dose increased the expression of Bdnf and Gdnf in the neural retina after 18 h, while the expression of Cntf was reduced by 70%. Daily dosing of wild-type mice from postnatal day P17 to P28 resulted in smaller increases in Bdnf and Gdnf expression, normal Cntf expression, and reduced Fgf2 expression (25%). Nrl gene expression was decreased by 50%, while Crx gene expression was not affected. Rod-specific expression of Mef2c and Nr2e3 was decreased substantially by VPA treatment, while Rhodopsin and Pde6b gene expression was normal at P28. Daily injections with VPA (P9-P21) dramatically slowed the loss of rod photoreceptors in Pde6b(rd1/rd1) mice. At age P21, VPA-treated mice had several extra rows of rod photoreceptor nuclei compared to PBS-injected littermates. Dosing started later (P14) or dosing every second day also rescued photoreceptors. In contrast, systemic VPA treatment of Pde6b(rd10/rd10) mice (P17-P28) reduced visual function that correlated with a slight increase in photoreceptor loss. Treating Pde6b(rd10/rd10) mice earlier (P9-P21) also failed to rescue photoreceptors. Treating wild-type mice earlier (P9-P21) reduced the number of photoreceptors in VPA-treated mice by 20% compared to PBS-treated animals. CONCLUSIONS: A single systemic dose of VPA can change retinal neurotrophic factor and rod-specific gene expression in the immature retina. Daily VPA treatment from P17 to P28 can also alter gene expression in the mature neural retina. While daily treatment with VPA could significantly reduce photoreceptor loss in the rd1 model, VPA treatment slightly accelerated photoreceptor loss in the rd10 model. The apparent rescue of photoreceptors in the rd1 model was not the result of producing more photoreceptors before degeneration. In fact, daily systemic VPA was toxic to wild-type photoreceptors when started at P9. However, the effective treatment period for Pde6b(rd1/rd1) mice (P9-P21) has significant overlap with the photoreceptor maturation period, which complicates the use of the rd1 model for testing of VPA's efficacy. In contrast, VPA treatment started after P17 did not cause photoreceptor loss in wild-type mice. Thus, the acceleration of photoreceptor loss in the rd10 model may be more relevant where both photoreceptor loss and VPA treatment (P17-P28) started when the central retina was mature.

Density functional calculations of the structural and electronic properties of (Y2O3)(n)(0,±1) clusters with n = 1-10.

We report results of ab initio calculations on yttrium oxide clusters using a plane wave pseudopotential method within density functional theory. (Y2O3)n clusters in the size range n = 1-10 prefer compact and symmetric globular configurations where preference for an octahedron unit of Y6O8 is seen. The evolution of the atomic structures shows similarity with that of the local structure in the bulk cubic (C-Y2O3) phase. The maximum coordinations of Y and O atoms are 6 and 4, respectively. The addition (removal) of an electron to (from) the lowest energy configurations of the neutral clusters induces significant changes for some of the cluster sizes. Sequential addition of a Y2O3 unit to the (Y2O3)n cluster leads to an increase in the binding energy. However, the HOMO-LUMO gap, ionization potential, and electron affinity do not show any systematic variation in these clusters with increasing size. The bonding characteristics have been studied using charge density and Bader charge analysis. The charge transfer from Y atoms to oxygens increases with the increase in the cluster size and approaches the value in bulk. The stability of the clusters is dominated by ionic Y-O interactions. However, a small degree of covalency is also seen in Y-O bonding. All the lowest energy configurations of neutral clusters prefer the lowest spin state and the ionic clusters prefer a doublet state.

Enhanced photocatalytic performance of CdFe2O4/Al2O3 nanocomposite for dye degradation.

In the present work, CdFe2O4/Al2O3 magnetic nanocomposite photocatalyst is successfully synthesized by simple sol-gel auto-combustion method. The role of this sample is studied as a photocatalyst. The influence of Al2O3 concentration with CdFe2O4 on the photocatalytic property is also studied. We have considered three weight percentage of Al2O3, 5%, 10%, and 20% with CdFe2O4. All the samples are characterized with X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), vibrating sample magnetometer (VSM), UV-Visible, and photoluminescence (PL) spectroscopy techniques. The 10% composite sample showed the lower particle size, higher surface area, enhanced porosity, higher saturation magnetization, and considerable band gap as compared to that of 5% and 20% CdFe2O4/Al2O3 as well as bare CdFe2O4 nanoparticles. The photocatalytic activity of the sample is evaluated towards the degradation of the xylenol orange (XO) dye under UV light. The degradation process of the dye is monitored spectrophotometrically. The performance in terms of removal efficiency is studied by varying the contact time, dye concentration and amount of catalyst. Among the three concentrations of Al2O3, the 10% weight concentration of Al2O3 with CdFe2O4 is found to be the optimal concentration and showed the higher degradation rate. After 30 min photocatalytic reaction, the degradation rate is 92.29% for 10% CdFe2O4/Al2O3 and for bare CdFe2O4, it is 85.79%. This work provides a new reference for designing Al2O3-based spinel ferrite nanocomposites and their role in wastewater management.

Optical properties of gallium oxide clusters from first-principles calculations.

The optical properties of the (Ga(2)O(3))(n) clusters, with n = 1-10, have been studied within the framework of time dependent density functional theory. The gallium oxide cluster geometries showed evolution from planar configuration (C(2v)) for Ga(2)O(3) to layered globular configuration (C(s)) for (Ga(2)O(3))(10) via corundum configuration (D(3d)) for (Ga(2)O(3))(4). For n ≤ 5, with the increase in coordination of Ga and O atoms, the polarizability decreases with the size of the cluster. For n ≥ 6, with the stabilization of average coordination number for gallium and oxygen atoms, the decrease in polarizability is very small. Further, the optical absorption spectra and the corresponding optical gap have been calculated. The overall shape of the calculated spectra strongly depend on cluster geometries. With the increase in size, the discrete spectra of small clusters evolves into quasicontinuous spectra. For n = 10, the spectra show a smooth absorption edge that is a characteristic of the bulk. It is observed that the optical gap oscillate with an increase in the cluster size. The calculated optical gap of these clusters are lower than the band gap of α- and ß-Ga(2)O(3) phases. The underestimation of the calculated values of the cluster optical gap is due to the use of local density approximation.

First-principles study of electronic and magnetic properties of transition metal adsorbed h-BNC2 sheets.

Adsorption of Fe, Co and Ni atoms on a hybrid hexagonal sheet of graphene and boron nitride is studied using density functional methods. Most favorable adsorption sites for these adatoms are identified for different widths of the graphene and boron nitride regions. Electronic structure and magnetic properties of the TM-adsorbed sheets are then studied in detail. The TM atoms change the electronic structure of the sheet significantly, and the resulting system can be a magnetic semiconductor, semi-metal, or a non-magnetic semiconductor depending on the TM chosen. This gives tunability of properties which can be useful in novel electronics applications. Finally, barriers for diffusion of the adatoms on the sheet are calculated, and their tendency to agglomerate on the sheet is estimated.

Structural, electronic and optical properties of metalloid element (B, Si, Ge, As, Sb, and Te) doped g-ZnO monolayer: A DFT study.

Stable geometries, electronic structure, and optical properties of ZnO monolayer doped with metalloid element (M = B, Si, Ge, As, Sb, and Te) atom have been studied using density functional theory. It is found that among these elements Ge, As, and Sb can be effectively doped at Zn site in the ZnO monolayer with the formation energies ranging from -1.02 to -0.96 eV. Except B element, all the metalloid atoms prefer to protrude out of the plane of the ZnO monolayer. The nonmagnetic nature of the ZnO monolayer is retained with the doping of B, Si, Ge, As, and Sb atom, while Te atom induces the magnetism in ZnO monolayer (2 µB). While doping of Si, As, Sb, and Te in ZnO monolayer resulted in a red shift in the absorption spectra of doped ZnO monolayer and the blue shift is observed for B and Ge doped ZnO. The static dielectric constant for ZnO monolayer is 1.49. With the doping of these metalloid elements in ZnO monolayer, the dielectric constant can be tuned from 1.36 to 2.84. These results are potentially useful for optoelectronic applications and the development of optical nanostructures.

Theoretical study of interaction of Fe13O8@Zn48O48 cluster with dopamine: Magnetic and optical properties.

In this study, we modelled the interaction of Fe13O8 and Fe13O8@Zn48O48 (core@shell) cluster with a biologically active dopamine molecule using density functional theory. First, the electronic, magnetic and optical properties of core@shell, Fe13O8@Zn48O48 cluster investigated and compared with isolated Fe13O8 and Zn48O48 clusters. Fe13O8@Zn48O48 cluster is found to be energetically stable. For Fe13O8 and Fe13O8@Zn48O48 clusters have the net magnetic moment 42 µB. The decrease in HOMO-LUMO gap of core@shell cluster as compared to that of isolated clusters reflects the higher reactivity. The results of the site dependent interaction of Fe13O8 and Fe13O8@Zn48O48 clusters with dopamine molecule are presented. The interaction strength is determined in terms of the cluster-dopamine complex binding energy and found to be enhanced for core@shell cluster than the Fe13O8. Furthermore, the calculated results predict that in presence of dopamine, the magnetic moment of Fe13O8 and Fe13O8@Zn48O48 cluster remains unaffected. The analysis of optical spectra of core@shell indicates the obvious red shift compared to Zn48O48 clusters. The optical spectra of Fe13O8@Zn48O48-dopamine shows the higher oscillator strength as compared to that of Fe13O8-dopamine complex. Fe13O8-dopamine complex gives rise to more quenched oscillator strengths as compared to that of bare iron oxide cluster. These results indicate interesting magneto-optical behaviour, which can be useful for biomedical applications.

PosMed-plus: an intelligent search engine that inferentially integrates cross-species information resources for molecular breeding of plants.

Molecular breeding of crops is an efficient way to upgrade plant functions useful to mankind. A key step is forward genetics or positional cloning to identify the genes that confer useful functions. In order to accelerate the whole research process, we have developed an integrated database system powered by an intelligent data-retrieval engine termed PosMed-plus (Positional Medline for plant upgrading science), allowing us to prioritize highly promising candidate genes in a given chromosomal interval(s) of Arabidopsis thaliana and rice, Oryza sativa. By inferentially integrating cross-species information resources including genomes, transcriptomes, proteomes, localizomes, phenomes and literature, the system compares a user's query, such as phenotypic or functional keywords, with the literature associated with the relevant genes located within the interval. By utilizing orthologous and paralogous correspondences, PosMed-plus efficiently integrates cross-species information to facilitate the ranking of rice candidate genes based on evidence from other model species such as Arabidopsis. PosMed-plus is a plant science version of the PosMed system widely used by mammalian researchers, and provides both a powerful integrative search function and a rich integrative display of the integrated databases. PosMed-plus is the first cross-species integrated database that inferentially prioritizes candidate genes for forward genetics approaches in plant science, and will be expanded for wider use in plant upgrading in many species.

Cs2TlBiI6: a new lead-free halide double perovskite with direct band gap.

The recent development of halide double perovskites A2B'B"X6 with favorable band gaps have provided a new search direction for stable Pb-free perovskite solar cells. Here, we propose a new lead free double perovskite Cs2TlBiI6 as a potential candidate for perovskite solar cell absorber. We probe the structural, electronic and optical properties of this material through density functional theory calculations. Our calculations on this material show that Cs2TlBiI6 adopt cubic double perovskite structure with space group Fm-3m. Using PBE exchange-correlation functional we obtain direct band gap of about 1.37 eV at the centre of Brillouin zone. The direct band gap and strong optical absorption of this material in the visible energy range of solar spectrum implies that Cs2TlBiI6 can be a potential candidate for perovskite based solar cell. Our fundamental calculations on this material would open up further possibility of experimental studies on TlBi based perovskite.

Ocular coherence tomography image data of the retinal laminar structure in a mouse model of oxygen-induced retinopathy.

The data presented in this article are related to the research paper entitled "Norrin treatment improves ganglion cell survival in an oxygen-induced model of retinal ischemia" (Dailey et al., 2017) [1] This article describes treatment with the human Norrin protein, an atypical Wnt-protein, to improve the survival of retinal ganglion cells in a murine model of Oxygen-Induced Retinopathy (OIR). That study utilized Optical coherence tomography (OCT) to visualize retinal layers at high resolution in vivo, and to quantify changes to nerve fiber layer thickness. Organization of the laminar structure of other retinal layers in this model in vivo, were not known because of uncertainties regarding potential artifacts during the processing of tissue for traditional histology. The OCT image data provided here shows researchers the retinal laminar structural features that exist in vivo in this popular mouse OIR model. Traditional H&E stained retinal tissue sections are also provided here for comparison.

Structural, energetic, electronic, bonding, and vibrational properties of Ga3O, Ga3O2, Ga3O3, Ga2O3, and GaO3 clusters.

The results of density functional theory based calculations on Ga3O, Ga3O2, Ga3O3, Ga2O3, and GaO3 clusters are reported here. A preference for planar arrangement of the constituent atoms maximizing the ionic interactions is found in the ground state of the clusters considered. The sequential oxidation of the metal-excess clusters increases the binding energy, but the sequential removal of a metal atom from the oxygen-excess clusters decreases the binding energy. The increase in the oxygen to metal ratio in these clusters is accompanied by increase in both electron affinity and ionization potential. The ionization induced structural distortions in the neutral clusters are relatively small, except those for Ga3O2. In anionic (cationic) clusters, the added (ionized) electron is shared by the Ga atoms, except in the case of GaO3. The vibrational frequencies and charge density analysis reveal the importance of the ionic Ga-O bond in stabilizing the gallium oxide clusters considered in this study.

Structural and electronic properties of neutral and ionic Ga(n)On clusters with n = 4-7.

We report the results of a theoretical study of neutral, anionic, and cationic Ga(n)On clusters (n = 4-7), focusing on their ground-state configurations, stability, and electronic properties. The structural motif of these small gallium oxide clusters appears to be a rhombus or a hexagonal ring with alternate gallium and oxygen atoms. With the increase in the cluster size from Ga4O4 to Ga7O7, the ground-state configurations show a transition from planar to quasi-planar to three-dimensional structure that maximizes the number of ionic metal-oxygen bonds in the cluster. The ionization-induced distortions in the ground state of the respective neutral clusters are small. However, the nature of the LUMO orbital of the neutral isomers is found to be a key factor in determining the ordering of the low-lying isomers of the corresponding anionic clusters. A sequential addition of a GaO unit to the GaO monomer initially increases the binding energy, though values of the ionization potential and the electron affinity do not show any systematic variation in these clusters.