Presence Of GR Research Articles

Poly(glycerol-sebacate)/poly(caprolactone)/graphene nanocomposites for nerve tissue engineering

In this study, mechanical, electrical, physical, and biological properties of polymeric matrixes comprising poly(glycerol-sebacate) (PGS) and poly(caprolactone) (PCL) with various weight ratio of PGS:PCL (1:3 and 1:1) were evaluated in order to apply as nerve guidance conduit. For this purpose, synthetic PGS pre-polymer was acquired using poly-condensation of glycerol and sebacic acid and characterized by attenuated total reflection-fourier transformed infrared (ATR-FTIR) and X-ray diffraction (XRD) spectroscopies. Furthermore, the effect of 1 wt% graphene (Gr) Nano sheets incorporation as filler, was investigated. Blending PGS with PCL significantly improves the hydrophilicity of the samples and improves cells attachment; however, their mechanical properties decreased dramatically. Presence of Gr within the polymeric matrix, significantly increased elastic modulus and tensile strength, which is possibly attributed to its superior mechanical properties and high aspect of ratio. Moreover, aforementioned polymeric matrixes, turned to conductive membranes by addition of Gr, which affected drastically on their biological properties; that way, 3, 4, 5-dimethylthiazol-2, 5-diphenyl tetrazolium bromide assay elucidated that only addition of 1 wt% Gr to the polymeric films resulted in improved cell survival and cell attachment for 7 days of cell seeding. In addition, cell attachment was enhanced considerably by increasing PGS up to 50 wt%, due to positive role of PGS on contact angle reduction. Therefore, the nano-composite film (50PGS-50PCL-1Gr) can be a promising substrate to use as a nerve guidance conduit.

Design of Copper and Titanium Dioxide Nanoparticles Doped with Reduced Graphene Oxide for Hydrogen Evolution by Water Splitting

TiO2-graphene (P25-GR, PG) nanocomposite was fabricated from P25 titania and graphite oxide by hydrothermal method, and then Cu nanoparticles (Cu NPs) were assembled in P25-GR composite (Cu- P25-GR, CPG) under microwave-assisted chemical reduction. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV–Vis absorption (UV–Vis) and Raman spectroscopies. Cu NPs were well dispersed on the surface of PG and are in metallic state. The ternary Cu-P25-GR (CPG) nanocomposites show an extended light absorption range and more efficient charge separation properties compared to binary P25-GR (PG) composite. Methylene blue photodegradation experiment proved that surface plasmon resonance (SPR) phenomenon had an effect on photoreaction efficiency. The corresponding hydrogen evolution rate for CPG prepared using 0.002 M Cu(NO3)2 solution was 10 times higher than with pure P25, and 2.3 times higher than with PG in the same test conditions. The improved photocatalytic performance can be attributed to the presence of GR in the prepared composite and to the SPR effect, leading to the longer lifetime of photogenerated electronhole pairs and faster interfacial charge transfer rate. We expect that our work would be useful for the further exploration of GR-based nanocomposites.

Production and Mechanical Testing of Aluminium Alloy Based Hybrid Metal Matrix Composite

The present work aims for uniformly dispersing Aluminium Oxide (Al2O3) and Graphite (Gr) particulates in an Aluminium Alloy Matrix to produce a hybrid composite and then to carry out the investigation and analysis of mechanical properties of developed composite. The particle size of Al2O3 and Gr were less than 45 microns. The stir casting technique is utilized to produce the hybrid composite having 2% Al2O3 with 0.5%, 1% Gr and 4% Al2O3 with 0.5%, 1% Gr. The composites were studied for density changes due to reinforcements, hardness, tensile strength and wear behaviour in Non-Heat Treated (NHT) conditions. The tests were done at the laboratory conditions as per ASTM guidelines. The Pin-On-Disc machine is used to test the sliding wear behaviour under dry conditions. The measured density is found to be decreasing as the reinforcement quantity is increased. The as cast Al alloy was found to be having highest hardness and the composites with increasing Gr exhibited lower hardness. The composite tensile strength is observed to be decreased in comparison to base alloy due to the presence of Gr but composite having highest quantity of Gr showed superior wear resistance which is mainly because the Gr particulates provide an inherent lubricating properties to composite. The composites developed in the present work can be used in the automobile and aerospace parts that are light in weight and require self-lubricating properties to enhance the wear resistance.

Guaranteed Renewable Life Insurance Under Demand Uncertainty

Guaranteed renewability is a prominent feature in many health and life insurance markets. It is well established in the literature that, when there is (only) risk type uncertainty, the optimal GR contract with renewal price set at the actuarially fair price for low risk types provides full insurance against reclassification risk. We develop a model that includes unpredictable (and unobservable) fluctuations in demand for life insurance as well as changes in risk type (observable) over individuals' lifetimes. The presence of demand type heterogeneity leads to the possibility that optimal GR contracts may have a renewal price that is either above or below the actuarially fair price of the lowest risk type in the population. Individuals whose type turns out to be high risk but low demand renew more of their GR insurance than is efficient due to the attractive renewal price. This results in incomplete insurance against re-classification risk. Although a first best efficient contract is not possible in the presence of demand type heterogeneity, the presence of GR contracts nonetheless improves welfare relative to an environment with only spot markets. Our results also apply to a comparison of environments with short versus long term (front loaded) insurance contracts.

The neurokinin‐2 receptor antagonist GR 159897 protects against neuroinflammation in the mouse enteric nervous system during colitis

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal (GI) disorder that affects 20% of Americans. The motility changes in IBS are driven by changes in the enteric nervous system (ENS). IBS has no cure, but recently, a neurokinin‐2 receptor (NK2R) antagonist has been shown to improve overall symptoms in a phase II study of diarrhea‐predominant IBS. However, the effects of NK2R antagonists on the ENS are not understood. We hypothesize that the beneficial effects of this antagonist on IBS are, in part, due to effects on the ENS. We tested our hypothesis by treating mice with the NK2R antagonist GR 159897 in a dinitrobenzene sulfonic acid (DNBS) model of colitis. To assess changes in the ENS, we used immunohistochemistry to quantify neuronal survival and performed a glial morphology analysis to assess reactive gliosis in the ENS. Calcium imaging recordings were performed in tissue preparations from mice expressing the genetically‐encoded calcium indicator GCaMP5g expressed under the control of the SOX10 promoter (SOX10::creERT2/+; PC::G5‐TdT+/−) or by loading cells with the calcium indicator dye Fluo4‐AM. Our results show that treatment with GR 159897 prevents increases in glial fibrillary acid protein (GFAP) immunoreactivity (n= 3–4 mice; p= 0.0141), increases in glial process length (n= 9–12 glia; p= 0.013) and neurodegeneration (n = 3–4; p= 0.0028). Immunohistochemical and calcium imaging data show that enteric glia express NK2Rs that are activated by neurokinin‐A (NKA). Glial responses to NKA were decreased in the presence of GR 159897 (n= 101–113 glia; p= 0.0001) or tetrodotoxin and were significantly reduced in samples from mice lacking glial connexin‐43 hemichannels (SOX10::creERT2/+; Cx43f/f mice; n= 50–113 glia; p= 0.0001). Glial responses to NKA were completely abolished in tissue samples from SOX10::creERT2/+; Cx43f/f mice in the presence of GR 159897 (n= 34–113; p= 0.0001). In conclusion, our data demonstrate that GR 159897 provides neuroprotection during colitis through mechanisms that involve decreasing glial activity driven by NKA. We speculate that these mechanisms could explain some of the clinical benefits of current NK2R antagonists in IBS.Support or Funding InformationRO1DK103723‐02S1

High-stress abrasive wear behavior of Al–Mg–Si hybrid composites using regression analysis

PurposeThe purpose of the present study is to analyze the wear behavior of developed aluminum hybrid composites under high-stress conditions through developed power law and quadratic equations.Design/methodology/approachThe abrasive wear behavior of Al–Mg–Si (Al 6082) alloy reinforced with hard silicon carbide (SiC) and soft graphite (Gr) particulates fabricated by stir casting route was studied at loads of 5-15 N, sliding distance of 75 m and abrasive grit size of 100-200 μm. The power law and quadratic equations were developed to understand the wear behavior with respect to the load applied and the abrasive grit size. The worn surfaces of the test specimens and grit papers were examined under scanning electron microscope.FindingsThe density and hardness of the hybrid composites decreased when compared to Al–SiC composites, whereas the wear properties improved because of the presence of Gr. There was further improvement in the wear properties of the materials because of T6 heat treatment. The change in abrasive wear mechanism was observed at a grit size of 125 μm when traversed from alloy to hybrid composite as indicated in terms of exponents in the power law equation. The worn surfaces of hybrid composite pins were comparable with those of alloy pins.Practical implicationsIn the automobile sector, components like cylinder liner, piston, crankshafts, brake drums, etc. also undergo abrasive wear along with sliding against the counter surface in working conditions.Originality/valueThe results prove that better wear resistance was obtained under the abrasion condition.

Graphene–Polyaniline composite based ultra-sensitive electrochemical sensor for non-enzymatic detection of urea

Detection of urea is of prime importance in food and water safety, dairy industries and environmental monitoring. Traditional methods to detect urea are either expensive and involve sophisticated instrumentation or are based on enzymatic approach of detection. Herein, we report a Graphene-Polyaniline (Gr-PANi) based electrochemical sensor for non-enzymatic detection of urea. Gr-PANi composite was synthesized by electro-deposition of PANi on the surface of Gr modified GCE using cyclic voltammetry (CV) technique. The presence of Gr and PANi in the composite was confirmed using a multitude of characterization techniques which included FESEM, XRD and Raman spectroscopy. The electrochemical behavior of urea at the surface of Gr-PANi modified GCE was studied by CV whereas urea sensing was performed by using simple current-potential (I–V) technique. The current response of the as-fabricated urea sensor was∼4.74 folds greater than that of pure PANi based sensor and ∼67.2 times greater than that of pure Gr based sensor. The sensing performance of the composite based urea sensor was optimized by varying the thickness of PANi film. The optimized sensor exhibited lower limit of detection (5.88μM), excellent reproducibility, selectivity and stability with an enhanced sensitivity of −226.9μA/μM cm2 (R2=0.993) in the range of 10μM–200μM. The reliability of the as-fabricated sensor was successfully investigated by using it to detect urea concentrations in samples of tap water and milk samples. This highly-sensitive Gr–PANi composite based urea sensor provides a simple, low cost, non-enzymatic approach for detection of urea that find numerous applications in clinical diagnostics, dairy industries, fertilizer plants and environmental monitoring.

Expression of the glucocorticoid receptor in breast cancer-associated fibroblasts

Cancer- associated fibroblasts (CAFs) are actively involved in breast carcinoma. Our previous study demonstrated that the majority of these CAFs were smooth muscle actin (SMA) positive and were therefore termed peritumoral myofibroblast (PMY). Glucocorticoid, linked or not with its receptor (GR), has been postulated to serve a major role in normal breast and breast carcinoma; however, their role in CAFs remains poorly understood. The aim of the present study was to assess the presence of GR in breast CAFs and particularly in PMY in 56 cases of invasive breast carcinoma in correlation with clinicopathological parameters, by immunohistochemistry. GR was observed in CAFs in 51 cases (91%) and were more frequent in luminal A subtype (19/19 cases; 100%). The stromal expression was statistically correlated with the tumor grade (P=0.03), the Ki-67 index (P=0.003) and the presence of GR in the epithelial component (P=0.01). The demonstration of a frequent expression of GR in breast CAFs may serve as an interesting target for future therapeutics for the regulation of the tumoral breast microenvironment.

Nitrogen-doped perovskite-type La2Ti2O7 decorated on graphene composites exhibiting efficient photocatalytic activity toward bisphenol A in water

Nitrogen-doped lanthanum titanate decorated on graphene sheets (GR/N-doped La2Ti2O7) used as photocatalyst was prepared by a two-step process. To synthesize GR/N-doped La2Ti2O7, La2Ti2O7 was initially developed under heat treatment in NH3 and subsequently decorated on GR by hydrothermal processing. The resulting GR/N-doped La2Ti2O7 was characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Characterization results indicated that N-doped La2Ti2O7 was approximately 6–8nm thick with single-crystalline perovskite structure and chemically attached onto GR nanosheets by the formation of TiN bond, TiC bond, and oxynitrides. The application of GR/N-doped La2Ti2O7 composites to bisphenol A decomposition exhibits high photocatalytic efficiency under irradiation compared with pure La2Ti2O7 materials. This finding was due to the synergistic effect of great adsorption, enhanced light absorption, efficient charge separation and transfer processes in the presence of GR, and reduced band gap energy because of N doping. This study provides new insights into the fabrication and practical application of high-performance photocatalysts in wastewater treatment.

Photocatalytic activity of Ag–TiO2-graphene ternary nanocomposites and application in hydrogen evolution by water splitting

TiO2-graphene (P25-GR, PG) nanocomposite was fabricated with P25 and graphite oxide through a hydrothermal method, and then Ag nanoparticles (Ag NPs) was assembled in P25-GR (Ag-P25-GR, APG) under microwave-assisted chemical reduction. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), photoluminescence spectrum (PL), UV–vis absorption spectrum (UV–vis) and Raman spectrum, respectively. The results showed that Ag NPs were well dispersed on the surface of PG with metallic state. The ternary Ag-P25-GR (APG) nanocomposites possessed the extended light absorption range and more efficient charge separation properties compared to binary P25-GR (PG). Methylene blue photodegradation experiment proved that surface plasmon resonance (SPR) phenomenon had an effect on photoreaction efficiency. The corresponding hydrogen evolution rate of APG prepared with 0.002 M AgNO3 solution was 7.6 times than pure P25 and 2.7 times than PG in the test condition. The improved photocatalytic performance can be attributed to the presence of GR and SPR effect, leading to the longer lifetime of photo-generated electron–hole pairs and faster interfacial charge transfer rate. This work indicates that the photoactivity of ternary GR-based nanocomposites is superior to the binary one. We expected our work could give a new train of thought on exploration of GR-based nanocomposites.

Graphene-Patched CNT/MnO2Nanocomposite Papers for the Electrode of High-Performance Flexible Asymmetric Supercapacitors

MnO2 has been widely studied as the pseudo-capactive electrode material of high-performance supercapacitors for its large operating voltage, low cost, and environmental friendliness. However, it suffers from low conductivity and being hardly handle as the electrodes of supercapacitors especially with flexibility, which largely limit its electrochemical performance and application. Herein, we report a novel ternary composite paper composed of reduced graphene sheet (GR)-patched carbon nanotube (CNT)/MnO2, which has controllable structures and prominent electrochemical properties for a flexible electrode of the supercapacitor. The composite paper was prepared by electrochemical deposition of MnO2 on a flexible CNT paper and further adsorption of GR on its surface to enhance the surface conductivity of the electrode and prohibit MnO2 nanospheres from detaching with the electrode. The presence of GR was found remarkably effective in enhancing the initial electrochemical capacitance of the composite paper from 280 F/g to 486.6 F/g. Furthermore, it ensures the stability of the capacitance after a long period of charge/discharge cycles. A flexible CNT/polyaniline/CNT/MnO2/GR asymmetric supercapacitor was assembled with this composite paper as an electrode and aqueous electrolyte gel as the separator. Its operating voltage reached 1.6 V, with an energy density at 24.8 Wh/kg. Such a composite structure derived from a multiscale assembly can offer not only a robust scaffold loading MnO2 nanospheres but also a conductive network for efficient ionic and electronic transport; thus, it is potentially promising as a novel electrode architecture for high-performance flexible energy storage devices.

Synthesis of a sulfur-graphene composite as an enhanced metal-free photocatalyst

A novel metal-free photocatalyst-sulfur/graphene (S/GR) composite—has been synthesized using a facile one-pot, two-step hydrothermal method with thiosulfate and graphene oxide (GO) as precursors. A green reductant—L-ascorbic acid—was used to transform GO to GR under mild conditions. The photocatalyst powders were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy. Experimental tests were conducted on the photocatalytic decomposition of methyl orange (MO) by different catalysts. Compared to pure α-S, the as-prepared S/GR composite showed much enhanced photocatalytic activity for the degradation of MO under both UV and solar light. The presence of GR also greatly increased the hydrophilicity and adsorption capacity of the catalyst material. The results indicate that the incorporation of GR with α-S results in a synergistic effect for the S-based photocatalysts offering more effective environmental applications. Open image in new window

Novel graphene/polyaniline nanocomposites and its photocatalytic activity toward the degradation of rose Bengal dye

The polyaniline/graphene (PANI–Gr) nanocomposites were prepared by the polymerization of aniline monomer with graphene (Gr) under in situ condition. The nanocomposites were utilized as the effective photocatalyst towards the photocatalytic degradation of Rose Bengal (RB) dye. The uniformity and the miscibility of PANI nanomaterials were improved with the increase of Gr contents which formed the advanced PANI–Gr nanocomposites. The absorption properties revealed the presence of Gr in PANI–Gr nanocomposites with significant interaction/bonding between PANI and Gr. The PANI–Gr nanocomposites possessed the partial hydrogen bonding between imine (NH) of PANI and the carboxylic group on the surface of Gr sheets. The prepared PANI–Gr nanocomposites delivered a significant degradation of RB dye by ∼56% within 3h under light illumination. As compared to PANI, the considerable degradation of RB dye was attributed to the presence of Gr sheets in PANI–Gr nanocomposites which might resulted the high photogenerated electron–hole pairs charge separation under light illumination.

Effect of the addition of alkanols of different topology to dipalmitoyl-phosphatidylcholine vesicles in the presence of gramicidin

In the present work, we analyze the effect of incorporation of the nonanol family (e.g., 1-Nonanol (1-N), 5-Nonanol (5-N), and 2,6-Dimethyl-4-Heptanol (2,6-DH)) into DPPC LUVs in the presence of different gramicidin concentrations. The principal aim of this work is to study the effect of alkanols solubilization on the physicochemical properties of lipid bilayers in the presence of peptide trans-membrane channels, that is, the effects of nonanol family in the interface of lipid–peptide region, considering that the study provides the analysis of a ternary system by direct excitation as well as by Fluorescence Resonance Energy Transfer. Fluorescence measurements were carried out at 20°C after direct excitation of the extrinsic probe or by Fluorescence Resonance Energy Transfer (FRET) from the tryptophan group of gramicidin. Alkanol incorporation decreases with increasing gramicidin content and branching of the additives. 1-N generates most important changes in the inner part of the bilayer, where it produces an increase in bulk acyl chain mobility. Similarly, 1-N significantly modifies the properties of the hydrophilic–hydrophobic interface region sensed by Laurdan, increasing the polarity of the probe microenvironment and/or increasing the relaxation time of interfacial water molecules. On the other hand, 1-N produces a decrease in PDA fluorescence lifetime, a result that can be explained by a significant amount of water entrance to the inner part of the bilayer. The same behavior was observed when pseudo-first-order quenching rate constants by oxygen were measured. 1-N produces an increase in mobility/solubility of the oxygen in the lipid membrane, an effect that is more noticeable in the deep region of the bilayer sensed by PDA, in the absence and in the presence of 2mol% of Gr. 1-N incorporation produces a greater reduction in GP value than 5-N and 2,6-DH when Laurdan was excited by FRET. These results show that 1-N has the greatest effect in the lipidic domains near the gramicidin channel. On the other hand, excimer–monomer ratios of PDA obtained by FRET show that 1-N reduces the lateral mobility of acyl chains near the lipid–gramicidin interface when gramicidin concentration in the lipid bilayer increases. This effect is more noticeable than that obtained by direct irradiation of the probe in the presence of 5-N and 2,6-DH. On the other hand, the addition of the three alkanols in the presence of Gr produces a noticeable increase in the water permeability, particularly for 1-N. In this context, we propose a scheme that represents the effect of 1-nonanol on the water outflow in DPPC LUVs in the absence and in the presence of Gr.

Managing the Grading Paradox: Leveraging the Power of Choice in the Classroom

How can management educators cultivate students' interest in the MBA classroom? Inspiring interest, an important antecedent of learning, can be an uphill battle due to the ubiquitous presence of gr...

Reductive transformation and mineralization of an azo dye by hydroxysulphate green rust preceding oxidation using H 2O 2 at neutral pH

In this study, the reactivity of hydroxysulphate green rust ( GR ( SO 4 2- ) ) toward reductive transformation, oxidative degradation and mineralization of organic compounds was evaluated using Methyl Red (MR) as model pollutant. The GR ( SO 4 2- ) was synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), Mössbauer spectroscopy and Fourier Transform Infrared (FTIR) analyses. Reductive decolourization of MR solution occurred in the presence of GR ( SO 4 2- ) , while no total organic carbon (TOC) decay was observed during the equilibration time. Significant TOC removal (87%) was noted when H 2O 2 was added to the GR ( SO 4 2- ) / MR mixture after the preliminary reduction step. UV–Vis analysis, dissolved iron and H 2O 2 concentration measurement, and batch sorption test showed that the heterogeneous Fenton-like reaction is the main mechanism by which the pollutant was mineralized. Increasing of H 2O 2/Fe(II) ratio did not affect significantly the mineralization rate of MR. However, slight decolourization of MR and absence of TOC abatement were noted when both MR and H 2O 2 were simultaneously mixed with the GR ( SO 4 2- ) . XRD analysis, Mössbauer spectroscopy and FTIR spectroscopy revealed that the oxidation end-products of GR ( SO 4 2- ) were mainly a poorly crystallized goethite when GR was oxidized after equilibrating with MR in solution. However, a badly crystallized iron oxide was formed when GR was immediately oxidized. In all cases, the interlayer anion ( SO 4 2- ) was ejected from GR structure to aqueous solution. These results suggest that the GR ( SO 4 2- ) / H 2 O 2 system could be used to promote the reduction/oxidation reaction of organic pollutants.

Dual Role of NRSF/REST in Activation and Repression of the Glucocorticoid Response

Restriction of glutamine synthetase to the nervous system is mainly achieved through the mutual function of the glucocorticoid receptor and the neural restrictive silencing factor, NRSF/REST. Glucocorticoids induce glutamine synthetase expression in neural tissues while NRSF/REST represses the hormonal response in non-neural cells. NRSF/REST is a modular protein that contains two independent repression domains, at the N and C termini of the molecule, and is dominantly expressed in nonneural cells. Neural tissues express however splice variants, REST4/5, which contain the repression domain at the N, but not at the C terminus of the molecule. Here we show that full-length NRSF/REST or its C-terminal domain can inhibit almost completely the induction of gene transcription by glucocorticoids. By contrast, the N-terminal domain not only fails to repress the hormonal response but rather stimulates it markedly. The inductive activity of the N-terminal domain is mediated by hBrm, which is recruited to the promoter only in the concomitant presence of GR. Importantly, a similar inductive activity is also exerted by the splice variant REST4. These findings raise the possibility that NRSF/REST exhibits a dual role in regulation of glutamine synthetase. It represses gene induction in nonneural cells and enhances the hormonal response, via its splice variant, in the nervous system.

EOCENE LARGER FORAMINIFERAL BIOSTRATIGRAPHY IN THE SOUTHERNMOST DAUPHINOIS DOMAIN (MARITIME ALPS, FRANCE-ITALY BORDER)

The Trucco Formation and the Nummulitic Limestone (Dauphinois Domain, Maritime Alps) are characterized by abundant larger foraminifera, specifically nummulitids, orthophragminids and encrusting foraminifera. In the Maritime Alps, previous studies suggest a late Lutetian age for the Trucco Formation and a late Lutetian-Priabonian age for the Nummulitic Limestone. Biostratigraphic analysis of the nummulitids, in 11 stratigraphic sections, allowed us to distinguish 3 biozones: MALF1 Zone: defined by the presence of Nummulites brongniarti d’Archiac & Haime, N. puschi d’Archiac, N. perforatus de Montfort, N. striatus (Bruguiere), N. cf. dufrenoyi d’Archiac & Haime, N. variolarius/incrassatus and Operculina schwageri Silvestri. MALF2 Zone: defined by the presence of Nummulites perforatus de Montfort, N. striatus (Bruguiere), N. cf. dufrenoyi d’Archiac & Haime, N. variolarius/incrassatus and Operculina schwageri Silvestri. MALF 3 Zone: defined by the presence of gr. Nummulites variolarius/incrassatus , N. striatus (Bruguiere) and Operculina schwageri Silvestri. According to current larger foraminiferal biozonal schemes, the age of these local biozones corresponds to the Bartonian p.p. Moreover, the comparison with biostratigraphic schemes established for the Dauphinois Domain and for the Tethyan area evidences that several typical nummulitid species of the late Bartonian are lacking in the southern Dauphinois Domain, probably due to a paleogeographic control.

Transglutaminase-dependent RhoA Activation and Depletion by Serotonin in Vascular Smooth Muscle Cells

The small G protein RhoA plays a major role in several vascular processes and cardiovascular disorders. Here we analyze the mechanisms of RhoA regulation by serotonin (5-HT) in arterial smooth muscle. 5-HT (0.1-10 microM) induced activation of RhoA followed by RhoA depletion at 24-72 h. Inhibition of 5-HT1 receptors reduced the early phase of RhoA activation but had no effect on 5-HT-induced delayed RhoA activation and depletion, which were suppressed by the 5-HT transporter inhibitor fluoxetine and the transglutaminase inhibitor monodansylcadaverin and in type 2 transglutaminase-deficient smooth muscle cells. Coimmunoprecipitations demonstrated that 5-HT associated with RhoA both in vitro and in vivo. This association was calcium-dependent and inhibited by fluoxetine and monodansylcadaverin. 5-HT promotes the association of RhoA with the E3 ubiquitin ligase Smurf1, and 5-HT-induced RhoA depletion was inhibited by the proteasome inhibitor MG132 and the RhoA inhibitor Tat-C3. Simvastatin, the Rho kinase inhibitor Y-27632, small interfering RNA-mediated RhoA gene silencing, and long-term 5-HT stimulation induced Akt activation. In contrast, inhibition of 5-HT-mediated RhoA degradation by MG132 prevented 5-HT-induced Akt activation. Long-term 5-HT stimulation also led to the inhibition of the RhoA/Rho kinase component of arterial contraction. Our data provide evidence that 5-HT, internalized through the 5-HT transporter, is transamidated to RhoA by transglutaminase. Transamidation of RhoA leads to RhoA activation and enhanced proteasomal degradation, which in turn is responsible for Akt activation and contraction inhibition. The observation of transamidation of 5-HT to RhoA in pulmonary artery of hypoxic rats suggests that this process could participate in pulmonary artery remodeling and hypertension.

Degradation of Disinfection Byproducts by Carbonate Green Rust

Disinfection byproducts (DBPs) in drinking water flowing through corroded iron or steel pipes may encounter carbonate green rust (GR(CO32-)), a mixed Fe(II)/Fe(lll) hydroxide mineral and potent reductant. This research was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs in the presence of GR(C032-). Trichloronitromethane was rapidly degraded to methylamine via sequential hydrogenolysis followed by nitro-reduction. Haloacetic acids reacted solely via sequential hydrogenolysis. Trichloroacetonitrile, 1,1,1-trichloropropanone, and trichloroacetaldehyde hydrate were transformed via hydrolysis and hydrogenolysis. Chloroform was unreactive over 300 h. The buffer identity affected reductive dehalogenation rates of DBPs, with faster rates in MOPS buffer than in carbonate buffer, the latter being representative of the buffer in drinking water systems. GR(CO32-) was unstable in both buffers and transformed to magnetite within 48 h. Thus, slower reacting compounds (half life >3 hours) were transformed by a combination of minerals. Reductive dehalogenation kinetics were influenced by DBP chemical structure and correlated with one-electron reduction potential.