The dependence of the hydrogen sorption capacity of single-walled carbon nanotubes on the concentration of catalyst

The adsorption of hydrogen on single-walled carbon nanotubes was measured using micro-gravimetric nitrogen and hydrogen adsorption isotherms at 77 K for gas pressures of up to 1 bar (nitrogen) and 12 bar (hydrogen). Results show that surface area and hydrogen uptake depend on the concentration of the iron catalyst used for making the nanotubes. Langmuir fits to the hydrogen uptake curves clearly show two adsorption energies for each sample which we attribute to the groove site for the higher adsorption energy and to the convex tube surface for the lower energy. We also present calculations of the binding energy of hydrogen on these same sites on SWCNTs and confirm that the groove site has a significantly higher (radius-dependent) binding energy than the surface site, consistent with the experimental values. This suggests that the use of the Langmuir model is appropriate to the adsorption of H2 on activated carbons for the temperature and pressure range investigated and could be used as a rapid way of estimating the average tube radius in the sample

Localization of NG2 immunoreactive neuroglia cells in the rat locus coeruleus and their plasticity in response to stress

The locus coeruleus (LC) nucleus modulates adaptive behavioural responses to stress and dysregulation of LC neuronal activity is implicated in stress-induced mental illnesses. The LC is composed primarily of noradrenergic neurons together with various glial populations. A neuroglia cell-type largely unexplored within the LC is the NG2 cell. NG2 cells serve primarily as oligodendrocyte precursor cells throughout the brain. However, some NG2 cells are in synaptic contact with neurons suggesting a role in information processing. The aim of this study was to neurochemically and anatomically characterise NG2 cells within the rat LC. Furthermore, since NG2 cells have been shown to proliferate in response to traumatic brain injury, we investigated whether such NG2 cells plasticity also occurs in response to emotive insults such as stress. Immunohistochemistry and confocal microscopy revealed that NG2 cells were enriched within the pontine region occupied by the LC. Close inspection revealed that a sub-population of NG2 cells were located within unique indentations of LC noradrenergic somata and were immunoreactive for the neuronal marker NeuN whilst NG2 cell processes formed close appositions with clusters immunoreactive for the inhibitory synaptic marker proteins gephyrin and the GABA-A receptor alpha3-subunit, on noradrenergic dendrites. In addition, LC NG2 cell processes were decorated with vesicular glutamate transporter 2 immunoreactive puncta. Finally, ten days of repeated restraint stress significantly increased the density of NG2 cells within the LC. The study demonstrates that NG2 IR cells are integral components of the LC cellular network and they exhibit plasticity as a result of emotive challenges

Seizures and Brain Tumor in Neurologically Intact Adult Patients: Role of Computerized Tomography (CT Scan)

CT scan of 13 patients with adult onset of seizures who were neurologically intact and otherwise asymptomatic revealed a supratentorial mass in all. Significant EEG abnormalities were recorded in five, and the isotope brain scan was positive in eight. In three patients, both studies were normal. Angiograms confirmed the location of tumor, and histology was established following craniotomy. The value of the CT scan as a screening test for detecting brain tumor in this group of seizure patients is evident

A Fast and Efficient Incremental Approach toward Dynamic Community Detection

Community detection is a discovery tool used by network scientists to analyze the structure of real-world networks. It seeks to identify natural divisions that may exist in the input networks that partition the vertices into coherent modules (or communities). While this problem space is rich with efficient algorithms and software, most of this literature caters to the static use-case where the underlying network does not change. However, many emerging real-world use-cases give rise to a need to incorporate dynamic graphs as inputs. In this paper, we present a fast and efficient incremental approach toward dynamic community detection. The key contribution is a generic technique called $\Delta-screening$, which examines the most recent batch of changes made to an input graph and selects a subset of vertices to reevaluate for potential community (re)assignment. This technique can be incorporated into any of the community detection methods that use modularity as its objective function for clustering. For demonstration purposes, we incorporated the technique into two well-known community detection tools. Our experiments demonstrate that our new incremental approach is able to generate performance speedups without compromising on the output quality (despite its heuristic nature). For instance, on a real-world network with 63M temporal edges (over 12 time steps), our approach was able to complete in 1056 seconds, yielding a 3x speedup over a baseline implementation. In addition to demonstrating the performance benefits, we also show how to use our approach to delineate appropriate intervals of temporal resolutions at which to analyze an input network

Spatiotemporal distribution of GABA_A receptor subunits within Layer II of mouse medial entorhinal cortex:implications for grid cell excitability

GABAergic parvalbumin-expressing (PV+) interneurons provide powerful inhibitory modulation of grid cells in layer II of the medial entorhinal cortex (MEC LII). However, the molecular machinery through which PV+ cells regulate grid cell activity is poorly defined. PV+ interneurons impart inhibitory modulation primarily via GABA-A receptors (GABAARs). GABAARs are pentameric ion channels assembled from a repertoire of 19 subunits. Multiple subunit combinations result in a variety of receptor subtypes mediating functionally diverse postsynaptic inhibitory currents. Whilst the broad expression patterns of GABAAR subunits within the EC have been reported, those expressed by individual MEC LII cell types, in particular grid cells candidates, stellate and pyramidal cells, are less well described. Stellate and pyramidal cells are distinguished by their selective expression of reelin (RE+) and calbindin (CB+) respectively. Thus, the overall aim of this study was to provide a high resolution analysis of the major (α and γ) GABAAR subunits expressed in proximity to somato-dendritic PV+ boutons, on RE+ and CB+ cells, using immunohistochemistry, confocal microscopy and quantitative RT-PCR (qPCR). Clusters immunoreactive for the α1 and γ2 subunits decorated the somatic membranes of both RE+ and CB+ cells and were predominantly located in apposition to clusters immunoreactive for PV and vesicular GABA transporter (VGAT), suggesting expression in GABAergic synapses innervated by PV interneurons. Although intense α2 subunit-immunopositive clusters were evident in hippocampal fields located in close proximity to the EC, no specific signal was detected in MEC LII RE+ and CB+ profiles. Immunoreactivity for the α3 subunit was detected in all RE+ somata. In contrast, only a sub-population of CB+ cells was α3 immunopositive. These included CB-α3 cells which were both PV+ and PV−. Furthermore, α3 subunit mRNA and immunofluorescence decreased significantly between P 15 and P 25, a period implicated in the functional maturation of grid cells. Finally, α5 subunit immunoreactivity was detectable only on CB+ cells, not on RE+ cells. The present data demonstrates that physiologically distinct GABAAR subtypes are selectively expressed by CB+ and RE+ cells. This suggests that PV+ interneurons could utilize distinct postsynaptic signaling mechanisms to regulate the excitability of these different, candidate grid cell sub-populations

The efficacy of ethanolic extract of lemon verbena on the skin infection due to Staphylococcus aureus in an animal model

Daily increasing of Staphylococcus aureus resistance to various antibiotics in particular penicillin and Methecilin has led the scientist to look fore new medicines in this area. In an in vitro laboratory studies, it has been demonstrated that ethanolic extract of Lemon verbena can prevent the growth of Staphylococcus aureus. In this study the efficacy of ethanolic extract of Lemon verbena against Staphylococcus aureus skin infection were assessed in an in vivo, in animal model. 200λ of Staphylococcus aureus suspension, were inoculated intradermally on the shoulder of 63 laboratory 20-30 g mice. the mice were divided in to 4 groups, 2 control groups: Negative (without treatment) and positive(treated with Mupirucin) and 2 test groups that treated for 7 days by ointment prepared from ethanolic extract of Lemon verbena (group3), or injection of Lemon verbena solution (group 4). The status of wounds, the rate of recovery was studied and the presence of local pus after dissection of mice on day 8 recorded and compared with each other. The wound appearance in the second day, on the injection site of S. aureus, in Group 1, 4, 3 and 2 were 84.2, 66.7, 46.2 and 23.1%, respectively. In the final day, the lesion still was remained in 78.9, 23.1, 92.3 and 77.7% in groups 1 -4, respectively. The necrotic and wide wounds were more observed in groups 1 and 3 vs two other groups. The results from this investigation indicate that the ointment prepared from ethanolic extract of Lemon verbena is a proper medication to prevent the skin infection by Staphylococcus aureus in early phase. © 2007 Asian Network for Scientific Information

Genetics and molecular mechanisms of resistance to powdery mildews in tomato (Solanum lycopersicum) and its wild relatives

Powdery mildews (PMs) cause disease in a wide range of plant species including important crops. Taking tomato as an example, here we review findings on the genetic basis and mechanisms of plant resistance to PMs. First, we present a summary of our research on tomato resistance to two PM species, with the focus on Oidium neolycopersici. We discuss the genetics of resistance to this pathogen in tomato. Then, we compare different forms of resistance mediated by different resistance genes based on molecular and cytological data. Also, we provide a comparison between these resistance genes in tomato with those in barley, Arabidopsis and wheat, in order to present a model for the genetic basis of resistance to PMs in plants. We try to accommodate these resistance mechanisms in the current model of plant innate immunity. At the end we discuss possibilities to translate these findings to practical approaches in breeding for resistance to PMs in crops

Syndapin-2 mediated transcytosis of amyloid-β across the blood-brain barrier

A deficient transport of amyloid-β across the blood-brain barrier, and its diminished clearance from the brain, contribute to neurodegenerative and vascular pathologies, such as Alzheimer's disease and cerebral amyloid angiopathy, respectively. At the blood-brain barrier, amyloid-β efflux transport is associated with the low-density lipoprotein receptor-related protein 1. However, the precise mechanisms governing amyloid-β transport across the blood-brain barrier, in health and disease, remain to be fully understood. Recent evidence indicates that the low-density lipoprotein receptor-related protein 1 transcytosis occurs through a tubulation-mediated mechanism stabilized by syndapin-2. Here, we show that syndapin-2 is associated with amyloid-β clearance via low-density lipoprotein receptor-related protein 1 across the blood-brain barrier. We further demonstrate that risk factors for Alzheimer's disease, amyloid-β expression and ageing, are associated with a decline in the native expression of syndapin-2 within the brain endothelium. Our data reveals that syndapin-2-mediated pathway, and its balance with the endosomal sorting, are important for amyloid-β clearance proposing a measure to evaluate Alzheimer's disease and ageing, as well as a target for counteracting amyloid-β build-up. Moreover, we provide evidence for the impact of the avidity of amyloid-β assemblies in their trafficking across the brain endothelium and in low-density lipoprotein receptor-related protein 1 expression levels, which may affect the overall clearance of amyloid-β across the blood-brain barrier

A preliminary study on pollen compatibility of some hazelnut cultivars in Iran

Pollen incompatibility is a major problem among hazelnut cultivars and can result in considerable crop loss in hazelnut orchards. Thus, identifying the level of self-compatibility of a cultivar and compatibility between cultivars are crucial aspects to selecting the proper pollenizers. Controlled self- and cross-pollinations were carried out in three local and four imported hazelnut cultivars. Based on cluster set, partial self-compatibility was found in cultivars Pashmine and Shastak, and complete self-compatibility in ‘Tabestane’. The best pollenizers for the cultivars Pashmine, Tabestane, Shastak, Barcelona, Segorbe, Daviana and Merveille were Segorbe, Barcelona, Segorbe, Shastak, Shastak, Pashmine and, Pashmine, respectively