875 resultados para Hydrogen pressures
Resumo:
We present measurements of hydrogen and oxygen isotopes in MORB glasses from Macquarie Island (SW. Pacific Ocean) coupled with determination of bulk H2O content by two independent techniques: total dehydration and FTIR. The incompatible trace elements in these glasses vary by a factor of 12 to 17, with K2O varying from 0.1 to 1.7 wt.%; these ranges reflect a variable degree of closed-system mantle melting, estimated from 1 to 15%. Water concentrations determined by the two techniques match well, yielding a range from 0.25 to 1.49 wt.% which correlates positively with all of the measured incompatible trace elements, suggesting that water is un-degassed, and behaves conservatively during mantle melting. Also, the agreement between the FTIR-determined and extracted water contents gives us confidence that the measured isotopic values of hydrogen reflect that of the mantle. Comparison of the range of water content with that of other incompatible trace elements allows estimation of the water partition coefficient in lherzolite, 0.0208 (ranging from 0.017 to 0.023), and the water content in the source, 386 ppm (ranging from 370 to 440 ppm). We observe a fairly narrow range in delta D and delta O-18 values of -75.5 +/- 4.5 parts per thousand and 5.50 +/- 0 .05 parts per thousand respectively, that can be explained by partial melting of normal lherzolitic mantle. The measured delta D and delta O-18 values of Macquarie Island glasses that range from nepheline- to hypersthene-normative, and from MORB to EMORB in composition, are identical to those in average global MORB. The observed lack of variation of delta D and delta O-18 with 1 to 15% degree of mantle melting is consistent with a bulk melting model of delta D and delta O-18 fractionation, in which water is rapidly scavenged into the first partial melt. The narrow ranges of delta D and delta O-18 in normal mantle are mostly due to the buffering effect of clino- and orthopyroxenes in the residual assemblage; additionally, fast ``wet'' diffusion of oxygen and hydrogen isotopes through the melting regions may further smooth isotopic differences. (C) 2012 Elsevier B.V. All rights reserved.
Resumo:
Pharmacological treatment of hypertension represents a cost-effective way for preventing cardiovascular and renal complications. To benefit maximally from antihypertensive treatment blood pressure (BP) should be brought to below 140/90 mmHg in every hypertensive patient, and even lower (< 130/80 mmHg) if diabetes or renal disease co-exists. Most of the time such targets cannot be reached using monotherapies. This is especially true in patients who exhibit a high cardiovascular risk. The co-administration of two agents acting by different mechanisms considerably increases BP control. Such preparations are not only efficacious, but also well tolerated, and some fixed low-dose combinations have a tolerability profile similar to placebo. This is for instance the case for the preparation containing the angiotensin-converting enzyme inhibitor perindopril (2 mg) and the diuretic indapamide (0.625 mg), a fixed low-dose combination that has recently been shown in controlled interventional trials to be more effective than monotherapies in reducing albuminuria, regressing cardiac hypertrophy and improving macrovascular stiffness. Fixed-dose combinations are becoming more and more popular and are even proposed by current hypertension guidelines as a first-line option to treat hypertensive patients.
Resumo:
Ydinvoimalaitokset on suunniteltu ja rakennettu niin, että niillä on kyky selviytyä erilaisista käyttöhäiriöistä ja onnettomuuksista ilman laitoksen vahingoittumista sekä väestön ja ympäristön vaarantumista. On erittäin epätodennäköistä, että ydinvoimalaitosonnettomuus etenee reaktorisydämen vaurioitumiseen asti, minkä seurauksena sydänmateriaalien hapettuminen voi tuottaa vetyä. Jäädytyspiirin rikkoutumisen myötä vety saattaa kulkeutua ydinvoimalaitoksen suojarakennukseen, jossa se voi muodostaa palavan seoksen ilman hapen kanssa ja palaa tai jopa räjähtää. Vetypalosta aiheutuvat lämpötila- ja painekuormitukset vaarantavat suojarakennuksen eheyden ja suojarakennuksen sisällä olevien turvajärjestelmien toimivuuden, joten tehokas ja luotettava vedynhallintajärjestelmä on tarpeellinen. Passiivisia autokatalyyttisiä vetyrekombinaattoreita käytetäänyhä useammissa Euroopan ydinvoimaitoksissa vedynhallintaan. Nämä rekombinaattorit poistavat vetyä katalyyttisellä reaktiolla vedyn reagoidessa katalyytin pinnalla hapen kanssa muodostaen vesihöyryä. Rekombinaattorit ovat täysin passiivisiaeivätkä tarvitse ulkoista energiaa tai operaattoritoimintaa käynnistyäkseen taitoimiakseen. Rekombinaattoreiden käyttäytymisen tutkimisellatähdätään niiden toimivuuden selvittämiseen kaikissa mahdollisissa onnettomuustilanteissa, niiden suunnittelun optimoimiseen sekä niiden optimaalisen lukumäärän ja sijainnin määrittämiseen suojarakennuksessa. Suojarakennuksen mallintamiseen käytetään joko keskiarvoistavia ohjelmia (Lumped parameter (LP) code), moniulotteisia virtausmalliohjelmia (Computational Fluid Dynamics, CFD) tai näiden yhdistelmiä. Rekombinaattoreiden mallintaminen on toteutettu näissä ohjelmissa joko kokeellisella, teoreettisella tai yleisellä (eng. Global Approach) mallilla. Tämä diplomityö sisältää tulokset TONUS OD-ohjelman sisältämän Siemens FR90/1-150 rekombinaattorin mallin vedynkulutuksen tarkistuslaskuista ja TONUS OD-ohjelmalla suoritettujen laskujen tulokset Siemens rekombinaattoreiden vuorovaikutuksista. TONUS on CEA:n (Commissariat à 1'En¬ergie Atomique) kehittämä LP (OD) ja CFD -vetyanalyysiohjelma, jota käytetään vedyn jakautumisen, palamisenja detonaation mallintamiseen. TONUS:sta käytetään myös vedynpoiston mallintamiseen passiivisilla autokatalyyttisillä rekombinaattoreilla. Vedynkulutukseen vaikuttavat tekijät eroteltiin ja tutkittiin yksi kerrallaan. Rekombinaattoreiden vuorovaikutuksia tutkittaessa samaan tilavuuteen sijoitettiin eri kokoisia ja eri lukumäärä rekombinaattoreita. Siemens rekombinaattorimalli TONUS OD-ohjelmassa laskee vedynkulutuksen kuten oletettiin ja tulokset vahvistavat TONUS OD-ohjelman fysikaalisen laskennan luotettavuuden. Mahdollisia paikallisia jakautumia tutkitussa tilavuudessa ei voitu havaita LP-ohjelmalla, koska se käyttäälaskennassa suureiden tilavuuskeskiarvoja. Paikallisten jakautumien tutkintaan tarvitaan CFD -laskentaohjelma.
Resumo:
BACKGROUND: While rifaximin was able to improve symptoms in patients with irritable bowel syndrome (IBS) in phase III trials, these results are yet to be repeated in phase IV studies. AIM: To evaluate the treatment response to rifaximin in IBS patients in a phase IV trial. METHODS: IBS patients underwent lactulose hydrogen breath testing (LHBT). LHBT-positive patients were treated with rifaximin for 14 days. Prior to treatment as well as at week 4 and 14 following the start of rifaximin treatment, patients completed a questionnaire assessing symptom severity on a Likert scale from 0 to 10. RESULTS: One hundred and six of 150 IBS patients (71%) were LHBT-positive and treated with rifaximin. As assessed at week 4 following commencement of the therapy, rifaximin provided significant improvement of the following IBS-associated symptoms: bloating (5.5±2.6 before the start of the treatment vs. 3.6±2.7 at week 4, P<0.001), flatulence (5.0±2.7 vs. 4.0±2.7, P=0.015), diarrhoea (2.9±2.4 vs. 2.0±2.4, P=0.005) and abdominal pain (4.8±2.7 vs. 3.3±2.5, P<0.001). Overall well-being also significantly improved (3.9 ± 2.4 vs. 2.7 ± 2.3, P < 0.001). Similar improvements in IBS symptoms were obtained at week 14. Eighty-six per cent of patients undergoing repetitive LHBT (55/64) tested negative at week 4. CONCLUSIONS: We found a high percentage of LHBT-positive IBS patients. IBS-associated symptoms (bloating, flatulence, diarrhoea, pain) were improved for a period of 3 months following 2 weeks of treatment with rifaximin. We conclude that rifaximin treatment alleviates symptoms in LHBT-positive IBS patients.
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The patent system was created for the purpose of promoting innovation by granting the inventors a legally defined right to exclude others in return for public disclosure. Today, patents are being applied and granted in greater numbers than ever, particularly in new areas such as biotechnology and information andcommunications technology (ICT), in which research and development (R&D) investments are also high. At the same time, the patent system has been heavily criticized. It has been claimed that it discourages rather than encourages the introduction of new products and processes, particularly in areas that develop quickly, lack one-product-one-patent correlation, and in which theemergence of patent thickets is characteristic. A further concern, which is particularly acute in the U.S., is the granting of so-called 'bad patents', i.e. patents that do not factually fulfil the patentability criteria. From the perspective of technology-intensive companies, patents could,irrespective of the above, be described as the most significant intellectual property right (IPR), having the potential of being used to protect products and processes from imitation, to limit competitors' freedom-to-operate, to provide such freedom to the company in question, and to exchange ideas with others. In fact, patents define the boundaries of ownership in relation to certain technologies. They may be sold or licensed on their ownor they may be components of all sorts of technology acquisition and licensing arrangements. Moreover, with the possibility of patenting business-method inventions in the U.S., patents are becoming increasingly important for companies basing their businesses on services. The value of patents is dependent on the value of the invention it claims, and how it is commercialized. Thus, most of them are worth very little, and most inventions are not worth patenting: it may be possible to protect them in other ways, and the costs of protection may exceed the benefits. Moreover, instead of making all inventions proprietary and seeking to appropriate as highreturns on investments as possible through patent enforcement, it is sometimes better to allow some of them to be disseminated freely in order to maximize market penetration. In fact, the ideology of openness is well established in the software sector, which has been the breeding ground for the open-source movement, for instance. Furthermore, industries, such as ICT, that benefit from network effects do not shun the idea of setting open standards or opening up their proprietary interfaces to allow everyone todesign products and services that are interoperable with theirs. The problem is that even though patents do not, strictly speaking, prevent access to protected technologies, they have the potential of doing so, and conflicts of interest are not rare. The primary aim of this dissertation is to increase understanding of the dynamics and controversies of the U.S. and European patent systems, with the focus on the ICT sector. The study consists of three parts. The first part introduces the research topic and the overall results of the dissertation. The second part comprises a publication in which academic, political, legal and business developments that concern software and business-method patents are investigated, and contentiousareas are identified. The third part examines the problems with patents and open standards both of which carry significant economic weight inthe ICT sector. Here, the focus is on so-called submarine patents, i.e. patentsthat remain unnoticed during the standardization process and then emerge after the standard has been set. The factors that contribute to the problems are documented and the practical and juridical options for alleviating them are assessed. In total, the dissertation provides a good overview of the challenges and pressures for change the patent system is facing,and of how these challenges are reflected in standard setting.
Resumo:
Oxidative stress is implicated in the pathogenesis of neurodegenerative disorders and hydrogen peroxide (H2O2) plays a central role in the stress. Huprines, a group of potent acetylcholinesterase inhibitors (AChEIs), have shown a broad cholinergic pharmacological profile. Recently, it has been observed that huprine X (HX) improves cognition in non transgenic middle aged mice and shows a neuroprotective activity (increased synaptophysin expression) in 3xTg-AD mice. Consequently, in the present experiments the potential neuroprotective effect of huprines (HX, HY, HZ) has been analyzed in two different in vitro conditions: undifferentiated and NGF-differentiated PC12 cells. Cells were subjected to oxidative insult (H2O2, 200 µM) and the protective effects of HX, HY and HZ (0.01 µM- 1 µM) were analyzed after a pre-incubation period of 24 and 48 hours. All huprines showed protective effects in both undifferentiated and NGF-differentiated cells, however only in differentiated cells the effect was dependent on cholinergic receptors as atropine (muscarinic antagonist, 0.1 µM) and mecamylamine (nicotinic antagonist, 100 µM) reverted the neuroprotection action of huprines. The decrease in SOD activity observed after oxidative insult was overcome in the presence of huprines and this effect was not mediated by muscarinic or nicotinic receptors. In conclusion, huprines displayed neuroprotective properties as previously observed in in vivo studies. In addition, these effects were mediated by cholinergic receptors only in differentiated cells. However, a non-cholinergic mechanism, probably through an increase in SOD activity, seems to be also involved in the neuroprotective effects of huprines.
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Aquaporins are water channel proteins that mediate the fine-tuning of cell membrane water permeability during development or in response to environmental stresses. The present work focuses on the oxidative stress-induced redistribution of plasma membrane intrinsic protein (PIP) aquaporins from the plasma membrane (PM) to intracellular membranes. This process was investigated in the Arabidopsis root. Sucrose density gradient centrifugation showed that exposure of roots to 0.5 mM H2O2 induces significant depletion in PM fractions of several abundant PIP homologs after 15 min. Analyses by single-particle tracking and fluorescence correlative spectroscopy showed that, in the PM of epidermal cells, H2O2 treatment induces an increase in lateral motion and a reduction in the density of a fluorescently tagged form of the prototypal AtPIP2;1 isoform, respectively. Co-expression analyses of AtPIP2;1 with endomembrane markers revealed that H2O2 triggers AtPIP2;1 accumulation in the late endosomal compartments. Life-time analyses established that the high stability of PIPs was maintained under oxidative stress conditions, suggesting that H2O2 triggers a mechanism for intracellular sequestration of PM aquaporins without further degradation. In addition to information on cellular regulation of aquaporins, this study provides novel and complementary insights into the dynamic remodeling of plant internal membranes during oxidative stress responses.
Resumo:
L'hydrogène sulfuré (H2S) est un gaz toxique retrouvé à l'état naturel et dans certains milieux industriels, à l'origine d'intoxication accidentelle, mais pouvant être également et facilement synthétisé de manière domestique. Des cas de suicide par hydrogène sulfuré ont ainsi été décrits à partir de produits ménagers dans la littérature depuis 2009, aux États-Unis et au Japon. La plupart présentait des délais post mortem (DPM) courts (moins de 72 heures). En France, les intoxications aiguës à l'H2S demeurent rares et sont le plus souvent liées à des accidents du travail. Nous rapportons ici le cas d'un homme âgé de 37 ans découvert à son domicile, en état de décomposition avancée avec un DPM de deux mois. Compte tenu de la présence d'une importante signalétique avisant du danger potentiel d'exposition à l'H2S, des mesures de précaution ont été mises en oeuvre dès la découverte du corps et poursuivies jusqu'aux opérations d'autopsie. Les analyses toxicologiques ont confirmé la présence d'H2S au niveau des prélèvements de cerveau et de muscle. Le cas présenté constitue le premier cas de suicide avec un délai post mortem long à l'H2S rapporté en France. Dans la littérature, les constatations macroscopiques à l'autopsie ne sont pas spécifiques tandis que les analyses toxicologiques reposent essentiellement sur la recherche et la quantification d'H2S. En raison de leur redistribution post mortem, les résultats de ces analyses doivent être interprétés avec prudence, et encore plus en cas de délai post mortem long et de phénomènes de putréfaction qui peuvent également être une source de génération d'H2S post mortem. Hydrogen sulfide (H2S) which is a poisonous gas found either in the natural state or in industrial environments and potentially linked with accidental intoxication, can also be easily handmade. Several cases of suicide by inhaling H2S produced by mixing household products have been reported in the literature since 2009 in USA and Japan. Most of them involved short post mortem delays up to 72 hours. In France, acute H2S poisoning remains rare and mostly accidental. We report the case of a 37-year-old man found at home, in an advanced stage of decomposition with a 2-month post mortem delay. As numerous warning signs about a high risk of H2S exposure were present, some precautionary measures were taken from the discovery of the cadaver to the autopsy. Toxicological analyses confirmed the presence of H2S in brain and muscle samples. This observation is the first French case with a long post mortem delay. As macroscopic findings in such cases are described to be unspecific in literature, toxicological analysis must focus on the detection and the quantification of H2S. However, due to the phenomena of post mortem drug redistribution and neo-formation, their results should be interpreted with much more caution when the post mortem delay is long. The potential increase in such voluntary-intoxication-related-deaths in France, similar to the recent Japanese and American waves of suicides, requires for forensic scientists, a good knowledge of both thanatological and toxicological pictures, and precautionary measures to adopt in such situations.
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The present study reports details of the stoichiometric characterization of the mixed complex system, V(H2O2)PAR, formed when vanadium adequately reacts with hydrogen peroxide and with 4-(2-Pyridilazo)Resorcinol. Also the presence of polynuclear species was investigated in order to elucidate about unambiguous assignment of the molar absorptivity, stability constant and composition of the complex. Two mathematical treatments methods of the experimental results were employed. From the results it can be concluded that this system corresponds to a mononuclear complex with 1:1:1 stoichiometry.
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The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.
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The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.
Resumo:
The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.
Resumo:
We assessed the effects of nutrient enrichment on three stream ecosystems running through distinct biomes (Mediterranean, Pampean and Andean). We increased the concentrations of N and P in the stream water 1.6–4-fold following a before–after control–impact paired series (BACIPS) design in each stream, and evaluated changes in the biomass of bacteria, primary producers, invertebrates and fish in the enriched (E) versus control (C) reaches after nutrient addition through a predictive-BACIPS approach. The treatment produced variable biomass responses (2–77% of explained variance) among biological communities and streams. The greatest biomass response was observed for algae in the Andean stream (77% of the variance), although fish also showed important biomass responses (about 9–48%). The strongest biomass response to enrichment (77% in all biological compartments) was found in the Andean stream. The magnitude and seasonality of biomass responses to enrichment were highly site specific, often depending on the basal nutrient concentration and on windows of ecological opportunity (periods when environmental constraints other than nutrients do not limit biomass growth). The Pampean stream, with high basal nutrient concentrations, showed a weak response to enrichment (except for invertebrates), whereas the greater responses of Andean stream communities were presumably favored by wider windows of ecological opportunity in comparison to those from the Mediterranean stream. Despite variation among sites, enrichment globally stimulated the algal-based food webs (algae and invertebrate grazers) but not the detritus-based food webs (bacteria and invertebrate shredders). This study shows that nutrient enrichment tends to globally enhance the biomass of stream biological assemblages, but that its magnitude and extent within the food web are complex and are strongly determined by environmental factors and ecosystem structure
Resumo:
We assessed the effects of nutrient enrichment on three stream ecosystems running through distinct biomes (Mediterranean, Pampean and Andean). We increased the concentrations of N and P in the stream water 1.6–4-fold following a before–after control–impact paired series (BACIPS) design in each stream, and evaluated changes in the biomass of bacteria, primary producers, invertebrates and fish in the enriched (E) versus control (C) reaches after nutrient addition through a predictive-BACIPS approach. The treatment produced variable biomass responses (2–77% of explained variance) among biological communities and streams. The greatest biomass response was observed for algae in the Andean stream (77% of the variance), although fish also showed important biomass responses (about 9–48%). The strongest biomass response to enrichment (77% in all biological compartments) was found in the Andean stream. The magnitude and seasonality of biomass responses to enrichment were highly site specific, often depending on the basal nutrient concentration and on windows of ecological opportunity (periods when environmental constraints other than nutrients do not limit biomass growth). The Pampean stream, with high basal nutrient concentrations, showed a weak response to enrichment (except for invertebrates), whereas the greater responses of Andean stream communities were presumably favored by wider windows of ecological opportunity in comparison to those from the Mediterranean stream. Despite variation among sites, enrichment globally stimulated the algal-based food webs (algae and invertebrate grazers) but not the detritus-based food webs (bacteria and invertebrate shredders). This study shows that nutrient enrichment tends to globally enhance the biomass of stream biological assemblages, but that its magnitude and extent within the food web are complex and are strongly determined by environmental factors and ecosystem structure
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The process of hydrogen desorption from amorphous silicon (ɑ-Si) nanoparticles grown by plasmaenhanced chemical vapor deposition (PECVD) has been analyzed by differential scanning calorimetry (DSC), mass spectrometry, and infrared spectroscopy, with the aim of quantifying the energy exchanged. Two exothermic peaks centered at 330 and 410 °C have been detected with energies per H atom of about 50 meV. This value has been compared with the results of theoretical calculations and is found to agree with the dissociation energy of Si-H groups of about 3.25 eV per H atom, provided that the formation energy per dangling bond in ɑ-Si is about 1.15 eV. It is shown that this result is valid for ɑ-Si:H films, too