906 resultados para lead dioxide
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Plants respond to environmental adversities, becoming an indicator for assessing the environment quality. In this aspect, chlorophyll contents as well, carotenoids are used as a reliable indicator to associate environmental quality and pollution, mainly regarding the toxicity of heavy metals in higher plants. So, we aimed to evaluate the content of chlorophyll a, b, and total chlorophylls and carotenoids in plants vetiver [Vetiveria zizanioides (L.) Nash], maize (Zea mays L.) cv. AG 1051, sunflower (Helianthus annuus L.) cv. BRS 122/V-2000, and castor beans (Ricinus communis L. ) cv . Northeastern BRS grown in contaminated soil with lead, with and without correction of soil pH, so they were used as indicators of metal stress by the soil. From the biochemical point of view, the correction of soil pH values caused chlorophyll a, b and total statistically higher for vetiver species and castor beans in the analyzed periods, except for the analysis performed 60 days after transplanting where only the species vetiver benefited from the correction of soil pH on the content of chlorophyll b and total. On the other hand plants without correction of soil pH showed a decrease of all chlorophyll levels. In addition, the largest increase in the synthesis of carotenoids, indicated that under stress the plants have developed alternative routes of dissipation of energy in order to avoid problems of photo-inhibition and photo-oxidation.
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Intestinal complications after laparoscopic cholecystectomy are rare and usually caused by direct injury sustained on trocar insertion. However, intestinal ischaemia has been reported as an unusual complication of the pneumoperitoneum. We describe a 55-years-old patient who underwent an uneventful laparoscopic cholecystectomy after an episode of acute cholecystitis. Initial recovery was complicated by development of increasing abdominal pain which led to open laparotomy on day 2. Gangrene of the distal ileum and right-sided colon was detected and small bowel resection with right colectomy and primary anastomosis was performed. Histological examination of the resected ileum showed features of venous hemorragic infarction and trombosis. In view of the proximity of the operation it is assumed that ileal ischaemia was precipitated by carbon dioxide pneumoperitoneum. Some studies have been demonstrated that, within 30 minutes of establishing a pneumoperitoneum at an intraabdominal pressure of 16 mmHg, cardiac output, blood flow in the superior mesenteric artery and portal vein decrease progressively. Carbon dioxide pneumoperitoneum may lead to mechanical compression of the splanchnic veins and mesenteric vasoconstriction as a result of carbon dioxide absortion. The distribution of the ischaemic segment of intestine is also unusual as the most precarious blood supply is traditionally at the splenic flexure of the colon. It has been suggested that intermittent decompression of the abdomen reduces the risk of mesenteric ischaemia during penumoperitoneum especially in patients with predisposing clinical features for arteriosclerosis intestinal. In present patient was observed intestinal venous infarction what remains unclear but we think the carbon dioxide pneumoperitoneum have been related to it.
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Att övervaka förekomsten av giftiga komponenter i naturliga vattendrag är nödvändigt för människans välmående. Eftersom halten av föroreningar i naturens ekosystem bör hållas möjligast låg, pågår en ständig jakt efter kemiska analysmetoder med allt lägre detektionsgränser. I dagens läge görs miljöanalyser med dyr och sofistikerad instrumentering som kräver mycket underhåll. Jonselektiva elektroder har flera goda egenskaper som t.ex. bärbarhet, låg energiförbrukning, och dessutom är de relativt kostnadseffektiva. Att använda jonselektiva elektroder vid miljöanalyser är möjligt om deras känslighetsområde kan utvidgas genom att sänka deras detektionsgränser. För att sänka detektionsgränsen för Pb(II)-selektiva elektroder undersöktes olika typer av jonselektiva membran som baserades på polyakrylat-kopolymerer, PVC och PbS/Ag2S. Fast-fas elektroder med membran av PbS/Ag2S är i allmänhet enklare och mer robusta än konventionella elektroder vid spårämnesanalys av joniska föroreningar. Fast-fas elektrodernas detektionsgräns sänktes i detta arbete med en nyutvecklad galvanostatisk polariseringsmetod och de kunde sedan framgångsrikt användas för kvantitativa bestämningar av bly(II)-halter i miljöprov som hade samlats in i den finska skärgården nära tidigare industriområden. Analysresultaten som erhölls med jonselektiva elektroder bekräftades med andra analytiska metoder. Att sänka detektionsgränsen m.hj.a. den nyutvecklade polariseringsmetoden möjliggör bestämning av låga och ultra-låga blyhalter som inte kunde nås med klassisk potentiometri. Den verkliga fördelen med att använda dessa blyselektiva elektroder är möjligheten att utföra mätningar i obehandlade miljöprov trots närvaron av fasta partiklar vilket inte är möjligt att göra med andra analysmetoder. Jag väntar mig att den nyutvecklade polariseringsmetoden kommer att sätta en trend i spårämnesanalys med jonselektiva elektroder.
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Ei-kineettinen vaikuttaminen on nousemassa – ellei jo noussut – kineettisen vaikuttamisen ohi sodankäynnin keinovalikoimassa. Viimeaikaisten konfliktien kokemukset ovat osoittaneet, että pelkällä fyysisellä voimankäytöllä ei päästä aina haluttuun lopputulokseen. Vaikka Irakissa ja Afganistanissa teknologialtaan ja kalustoltaan ylivertaiset länsiliittouman joukot saivat sotilaallisia voittoja alivoimaisista vastustajistaan, ovat ne olleet vaikeuksissa sissisotaa käyvien pienten ryhmittymien kanssa, eivätkä alueet rauhoittuneet varsinaisten sotatoimien päätyttyä. Tällöin on aloitettava taistelu sydämistä ja mielistä – ”Hearts and Minds” – ja tässä taistelussa ei pärjätä pelkästään tankein ja pommein. Omaa sanomaa levittämällä pyritään voittamaan kansan tuki itsensä taakse ja samalla viemään kannatus taistelevilta sissijoukoilta. Ilman voittoa informaatiorintamalla ei operaatiota voi voittaa. Fyysisellä voimankäytöllä on sen tuhovoiman lisäksi myös aina psykologinen vaikutus. Pitkään kestänyt tykistökeskitys aiheuttaa kranaattikauhua ja voi lamauttaa sen kohteeksi joutuneet henkisesti. Vaikutus voi ilmentyä myös muissa, kuin varsinaisen keskityksen kohteeksi joutuneissa – tieto massiivisesta tuhosta voi murentaa taistelutahdon naapurijoukoissa ilman, että se joutuisi edes tulen alle. Omissa joukoissa tieto massiivisesta tulivoimasta tukena voi vaikuttaa taistelutahtoa nostavasti. Siten myös perinteinen, fyysinen vaikuttaminen on yhä keskeinen väline psykologisessa vaikuttamisessa. Tutkimustehtävänä on selvittää, miten eri suorituskykyjä käytettiin psykologisen vaikuttamisen välineinä Israelin ja Hamasin välisessä konfliktissa 27.12.2008 - 19.1.2009. Tutkimuskysymyksinä ovat mitä eri suorituskykyjä ja niitä tukevia toimintoja käytettiin psykologisen vaikuttamisen välineinä sekä voidaanko niillä todeta olleen mitään vaikutuksia. Tutkimusmenetelmänä käytettiin teoriaohjaavaa aineiston analyysia, jossa aineisto on kerätty operaation ajalta eri uutissivustoilta sekä eri laitosten ja järjestöjen tutkimusraporteista ja selvityksistä. Aineistosta on etsitty havaintoja viitekehyksen mukaisten suorituskykyjen käytöstä ja tämän jälkeen on pyritty arvioimaan, miten kyseistä suorituskykyä käytettiin psykologisen vaikuttamisen välineenä ja olisiko sillä ollut vaikutusta. Operaation aikana molemmat osapuolet käyttivät omia suorituskykyjään vaikuttaakseen eri kohdeyleisöihin. Vaikuttamisen luonne riippui kohdeyleisöstä. Oman väestön ja joukon taistelutahtoa yritettiin vahvistaa, vastustajan taistelutahtoa yritettiin murentaa ja ulkopuolisia tahoja houkuteltiin antamaan itselle tukea ja vastustamaan toista osapuolta. Eri suorituskykyjen käytön vaikutuksia on vaikea arvioida etukäteen ja niiden aiheuttamat vaikutukset voivat olla haluttuja tai ei-haluttuja, yllättäviä tai odotettuja tai täysin arvaamattomia. Pienistäkin tapahtumista voi syntyä valtava vaikutus, mikäli se tapahtuu oikeaan aikaan oikeassa paikassa – tai päinvastoin väärässä paikassa väärään aikaan. Huolellisimminkin suunnitellut psykologiset operaatiot taas saattavat kaatua mitättömiltä tuntuviin sivuseikkoihin.
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Increased emissions of greenhouse gases into the atmosphere are causing an anthropogenic climate change. The resulting global warming challenges the ability of organisms to adapt to the new temperature conditions. However, warming is not the only major threat. In marine environments, dissolution of carbon dioxide from the atmosphere causes a decrease in surface water pH, the so called ocean acidification. The temperature and acidification effects can interact, and create even larger problems for the marine flora and fauna than either of the effects would cause alone. I have used Baltic calanoid copepods (crustacean zooplankton) as my research object and studied their growth and stress responses using climate predictions projected for the next century. I have studied both direct temperature and pH effects on copepods, and indirect effects via their food: the changing phytoplankton spring bloom composition and toxic cyanobacterium. The main aims of my thesis were: 1) to find out how warming and acidification combined with a toxic cyanobacterium affect copepod reproductive success (egg production, egg viability, egg hatching success, offspring development) and oxidative balance (antioxidant capacity, oxidative damage), and 2) to reveal the possible food quality effects of spring phytoplankton bloom composition dominated by diatoms or dinoflagellates on reproducing copepods (egg production, egg hatching, RNA:DNA ratio). The two copepod genera used, Acartia sp. and Eurytemora affinis are the dominating mesozooplankton taxa (0.2 – 2 mm) in my study area the Gulf of Finland. The 20°C temperature seems to be within the tolerance limits of Acartia spp., because copepods can adapt to the temperature phenotypically by adjusting their body size. Copepods are also able to tolerate a pH decrease of 0.4 from present values, but the combination of warm water and decreased pH causes problems for them. In my studies, the copepod oxidative balance was negatively influenced by the interaction of these two environmental factors, and egg and nauplii production were lower at 20°C and lower pH, than at 20°C and ambient pH. However, presence of toxic cyanobacterium Nodularia spumigena improved the copepod oxidative balance and helped to resist the environmental stress, in question. In addition, adaptive maternal effects seem to be an important adaptation mechanism in a changing environment, but it depends on the condition of the female copepod and her diet how much she can invest in her offspring. I did not find systematic food quality difference between diatoms and dinoflagellates. There are both good and bad diatom and dinoflagellate species. Instead, the dominating species in the phytoplankton bloom composition has a central role in determining the food quality, although copepods aim at obtaining as a balanced diet as possible by foraging on several species. If the dominating species is of poor quality it can cause stress when ingested, or lead to non-optimal foraging if rejected. My thesis demonstrates that climate change induced water temperature and pH changes can cause problems to Baltic Sea copepod communities. However, their resilience depends substantially on their diet, and therefore the response of phytoplankton to the environmental changes. As copepods are an important link in pelagic food webs, their future success can have far reaching consequences, for example on fish stocks.
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PURPOSE: To evaluate the effectiveness, recurrence rate, and complications of carbon-dioxide laser vaporization in the treatment of Bartholin's gland cysts. METHODS: A retrospective study including 127 patients with symptomatic Bartholin' gland cysts submitted to carbon-dioxide laser vaporization at our institution from January 2005 to June 2011. Patients with Bartholin's gland abscesses and those suspected of having neoplasia were excluded. All procedures were performed in an outpatient setting under local anaesthesia. Clinical records were reviewed for demographic characteristics, anatomic parameters, intraoperative and postoperative complications, and follow-up data. Data were stored and analyzed in Microsoft Excel® 2007 software. A descriptive statistical analysis was performed, and its results were expressed as frequency (percentage) or mean±standard deviation. Complication, recurrence, and cure rates were calculated. RESULTS: The mean age of the patients was 37.3±9.5 years-old (range from 18 to 61 years-old). Seventy percent (n=85) of them were multiparous. The most common symptom was pain and 47.2% (n=60) of patients had a history of previous medical and/or surgical treatment for Bartholin's gland abscesses. Mean cyst size was 2.7±0.9 cm. There were three (2.4%) cases of minor intraoperative bleeding. Overall, there were 17 (13.4%) recurrences within a mean of 14.6 months (range from 1 to 56 months): ten Bartholin's gland abscesses and seven recurrent cysts requiring reintervention. The cure rate after single laser treatment was 86.6%. Among the five patients with recurrent disease that had a second laser procedure, the cure rate was 100%. CONCLUSIONS: At this institution, carbon-dioxide laser vaporization seems to be a safe and effective procedure for the treatment of Bartholin's gland cysts.
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The present study describes the occurrence of lead poisoning in cattle and chickens in Pará, Brazil. In a lot composed of 80 calves from a dairy herd, 10 animals became sick and nine died, but one animal recovered after being removed from the paddock. Upon inspection of this paddock, the presence of truck batteries used to store energy captured by solar panels was found. The clinical signs observed in calves included difficult breathing, nasal discharge, excessive salivation, corneal opacity, pushing of the head against objects and recumbency. The chickens had decreased oviposition and produced eggs with thin or malformed shells. The necropsy findings of the cattle, as well as the histopathological changes observed, were of little significance except for one animal that showed mild astrocytosis histopathology in the cerebral cortex. In one of the chickens, renal histopathology showed mild multifocal acute tubular necrosis. The mean lead concentrations in the livers and kidneys of the cattle were 93.91mg/kg and 209.76mg/kg, respectively, and the mean concentration detected in chicken livers was 105.02mg/kg. It was concluded that the source of lead poisoning in these calves and chickens were the truck battery plates, which were within reach of the animals.
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Verkottuneessa ja globaalissa maailmassa ei pelkkään kineettiseen vaikuttamiseen perustuva sodankäynti ole tuottanut enää toivottuja tuloksia ja siksi sekä valtiolliset että ei-valtiolliset toimijat ovatkin kääntäneet katseensa muihin keinoihin. Vaikuttaminen on siirtymässä maa-likeskeisyydestä mielikeskeisyyteen, jossa maaleina ovat kohteen arvot, asenteet, ajatukset ja lopulta identiteetti. Näihin vaikuttamalla halutaan muuttaa kohteen käyttäytymistä omalta kannalta suotuisaan suuntaan. Teknologiset vallankumoukset ovat lisänneet informaation määrää eksponentiaalisesti ja tä-hän globaaliin informaatioon on alati kasvavalla joukolla pääsy lähes milloin ja mistä tahan-sa. Jokainen informaatioon käsiksi pääsevä voi myös ryhtyä tuottamaan informaatiota mui-den saataville, ja tämä viestinnällinen mullistus on vaikuttanut radikaalisti myös länsimaiseen sotataitoon informaation noustessa yhdeksi ratkaisevaksi tekijäksi nykyajan ja tulevaisuuden konflikteissa. Tapahtumista, joista vielä sata vuotta sitten kuultiin vasta päiviä tai viikkoja niiden jälkeen, saadaan tänä päivänä nähdä reaaliaikaista kuvavirtaa mobiilipäätelaitteen vä-lityksellä. Tämä mullistus on pakottanut niin valtiolliset kuin ei-valtiollisetkin toimijat kiin-nittämään entistä enemmän huomiota taisteluun informaatiosta informaatioympäristössä sekä yleisön mielikuvista ja mielipiteistä. Fyysisestä kontaktista voittajana selvinnyt osapuoli voi jäädä häviäjän rooliin, mikäli taistelu informaatiorintamalla hävitään. Totuus on toisarvoista, mielikuvat ratkaisevat. Jotta taistelu mielikuvista, ajatuksista ja asenteista olisi mahdollisimman tehokasta, täytyy kunkin osapuo-len organisoida omat ponnistuksensa resurssien käytön optimoimiseksi karsien päällekkäi-syydet ja ristiriidat omista sanomistaan. Kaikkien eri tahojen täytyy siis sovittaa omat vies-tinsä palvelemaan ylemmän tahon tavoitteita päätyen aina politiikan määrittämään tavoittee- seen. Tätä kutsutaan strategiseksi kommunikaatioksi, jota voidaan pitää ajattelua ohjaavana mallina tai jopa eräänlaisena sotataidollisena paradigmana. Tässä työssä tutkittiin Israelin suorittamaa sotilaallista operaatiota Gazan kaistaleella vuosien 2008 – 2009 vaihteessa. Operaatiosta käytetään yleisesti länsimaissa nimeä Cast Lead. Ope-raation tarkoituksena oli iskeä Gazassa toimivaa, länsimaiden terroristijärjestöksi katsomaa Hamas-järjestöä vastaan ja lopettaa sen tekemät raketti- ja kranaatti-iskut Israeliin. Tutki-muksen tarkoituksena oli selvittää, miten strateginen kommunikaatio oli järjestetty ja toteu-tettu Israelissa operaatioon liittyen. Työ on jatkoa tutkijan esiupseerikurssilla 64 laatimalle työlle ”Psykologinen vaikuttaminen CAST LEAD -operaatiossa”. Lähdemateriaalin avulla muodostettiin strategisen kommunikaation viitekehys, jota käytettiin analyysirunkona teoriaohjaavalle sisällön analyysille. Tutkittavaa operaatiota käsittelevästä avoimista lähteistä kerättyä aineistoa analysoitiin strategisen kommunikaation viitekehyksen kautta keräten havaintoja viitekehyksen eri osa-alueiden esiintymisestä. Tällä tavalla kyettiin muodostamaan kuva Israelin strategisen kommunikaation organisoinnista, eri toimijoista se-kä niiden vastuista ja eri tavoista, joilla viestejä välitettiin millekin kohdeyleisölle. Samalla pyrittiin hahmottelemaan Israelin narratiivia tutkittavaan operaatioon. Työ jakautuu kolmeen osaan. Ensimmäisessä osassa luvuissa yksi ja kaksi käsitellään tutki-muksen teoreettiset taustat, menetelmät ja metodit sekä määritellään keskeisimmät käsitteet. Luvussa kolme käsitellään strategisen kommunikaation osatekijät käsiteanalyysin kautta. Toisessa osassa luvuissa neljä ja viisi käsitellään operaation kulku ja tausta pääpiirteittäin se-kä jaotellaan strategisen kommunikaation viitekehyksen avulla tehdyt havainnot kuvaamaan strategisen kommunikaation toteutumista operaatiossa. Kolmannessa osassa luvussa kuusi käsitellään johtopäätökset sekä arvioidaan tutkimuksen toteutumista sekä jatkotutkimustarpeita. Strategisen kommunikaation viitekehys muodostettiin ulkomaisten ja suomalaisten lähdete-osten avulla. Strategisen kommunikaation käsiteanalyysissä käsiteltiin strategiaa, kommuni-kaatiota sekä näiden taustalla olevia teorioita eri lähteiden avulla ja siten pyrittiin muodosta-maan laaja-alainen kuva siitä, mitä strateginen kommunikaatio on ja miten se toimii. Tutki-muksen aineisto koottiin avoimista lähteistä internetin eri mediatalojen sivuilta ja sitä täy-dennettiin virallisten ja epävirallisten tahojen sivustojen tarjoamalla informaatiolla. Aineiston perusteella kyettiin muodostamaan kuva Israelin strategisen kommunikaation or- ganisoinnista vastuineen sekä hahmottelemaan viestejä, teemoja ja narratiivia. Strategisen kommunikaation vaikuttavuutta tässä operaatiossa on mahdotonta mitata aukottomasti, koska tapaustutkimukselle luonteenomaisesti käsiteltävänä oli ainutlaatuinen tosielämän tapahtuma ja siten suoraa vertailukohtaa ei ole. Verrokkina voidaan kuitenkin käyttää aiempia Israelin sotilaallisia toimia, joissa informaatioympäristöön ei oltu kiinnitetty yhtä paljon huomiota. Näin ollen voidaan vetää johtopäätöksiä operaation vaikuttavuudesta vertailemalla esimer-kiksi näiden ajallisesti läheisten operaatioiden aiheuttamia reaktioita maailmalla.
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This thesis presents a one-dimensional, semi-empirical dynamic model for the simulation and analysis of a calcium looping process for post-combustion CO2 capture. Reduction of greenhouse emissions from fossil fuel power production requires rapid actions including the development of efficient carbon capture and sequestration technologies. The development of new carbon capture technologies can be expedited by using modelling tools. Techno-economical evaluation of new capture processes can be done quickly and cost-effectively with computational models before building expensive pilot plants. Post-combustion calcium looping is a developing carbon capture process which utilizes fluidized bed technology with lime as a sorbent. The main objective of this work was to analyse the technological feasibility of the calcium looping process at different scales with a computational model. A one-dimensional dynamic model was applied to the calcium looping process, simulating the behaviour of the interconnected circulating fluidized bed reactors. The model incorporates fundamental mass and energy balance solvers to semi-empirical models describing solid behaviour in a circulating fluidized bed and chemical reactions occurring in the calcium loop. In addition, fluidized bed combustion, heat transfer and core-wall layer effects were modelled. The calcium looping model framework was successfully applied to a 30 kWth laboratory scale and a pilot scale unit 1.7 MWth and used to design a conceptual 250 MWth industrial scale unit. Valuable information was gathered from the behaviour of a small scale laboratory device. In addition, the interconnected behaviour of pilot plant reactors and the effect of solid fluidization on the thermal and carbon dioxide balances of the system were analysed. The scale-up study provided practical information on the thermal design of an industrial sized unit, selection of particle size and operability in different load scenarios.
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The aim of this thesis was to identify the best grease removal technique with the application of low power of UV light to TiO2 coated grease filters. The treatment with various power series of ozone generating and ozone free lamps to normal grease filters and TiO2 coated grease filters were examined and the obtained results are compared to each other in this paper. The effect of ozone reaction was observed and compared with the effect of TiO2. The experiments were solely based on the photo oxidation and photo catalytic oxidation reactions. TiO2 is a green catalyst used in the photocatalytic reaction. Sunflower oil was used for grease production and tetracholoroethylene as a solvent. Grease samples were collected from the ventilation duct connected to the cooking hood system. Sample extraction was done in ultrasonic bath with the principle of sonication. The sample analysis was done by FTIR machine. The result determining the concentration of grease was the quantification of saturated C-H bonds in the chosen peak group of the spectrum. A very low power of UVC light functions perfectly with the Titanium dioxide. The experimental results have shown the combined treatment of titanium dioxide and UV light is an effective method in grease removal process. The photocatalytic reaction with titanium dioxide is better than photo oxidation reaction with ozone treatment. Photocatalytic reaction is environmentally friendly, energy efficient and economical.
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We investigated the effectiveness of Nitroxin inoculation on lead (Pb) and nutrient uptakes by little seed canary grass. The factors tested included inoculation (or not) with Nitroxin and different soil concentrations of Pb (0, 200, 400 and 800mgPbkg-1 soil). Increasing soil concentrations of Pb decreased stem, leaf and root dry weights. Shoot phosphorus concentrations increased in parallel with increasing soil Pb concentrations. Nitroxin inoculation did not alter the phosphorus concentration of the roots. The Pb translocation factor was >1 in inoculated treatments in the Pb soil concentration range of 200 to 400mgkg-1; the translocation factor for 800mgPbkg‑1 with no inoculation of Nitroxin was, however, <1. Our results indicated that the Pb bioaccumulation factor for little seed canary grass was <1, indicating that it is a Pb excluding plant.
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We have previously demonstrated that acute third ventricle injections of both Pb2+ and Cd2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. ß-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb2+ (3, 30 and 300 pmol/rat) or Cd2+ (0.3, 3 and 30 pmol/rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO + saline = 5.78 ± 0.54 ml/100 g; ISO + NaAc = 6.00 ± 0.6 ml/100 g). After the same period, animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank 0.78 ± 0.23 ml/100 g while those receiving ISO and pretreated with the highest dose of CdCl2 (30 pmol/rat) presented a water intake of 0.7 ± 0.30 ml/100 g. Third ventricle injections of CdCl2 (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb2+ and Cd2+ inhibit water intake induced by central ß-adrenergic stimulation
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Environmental issues, including global warming, have been serious challenges realized worldwide, and they have become particularly important for the iron and steel manufacturers during the last decades. Many sites has been shut down in developed countries due to environmental regulation and pollution prevention while a large number of production plants have been established in developing countries which has changed the economy of this business. Sustainable development is a concept, which today affects economic growth, environmental protection, and social progress in setting up the basis for future ecosystem. A sustainable headway may attempt to preserve natural resources, recycle and reuse materials, prevent pollution, enhance yield and increase profitability. To achieve these objectives numerous alternatives should be examined in the sustainable process design. Conventional engineering work cannot address all of these substitutes effectively and efficiently to find an optimal route of processing. A systematic framework is needed as a tool to guide designers to make decisions based on overall concepts of the system, identifying the key bottlenecks and opportunities, which lead to an optimal design and operation of the systems. Since the 1980s, researchers have made big efforts to develop tools for what today is referred to as Process Integration. Advanced mathematics has been used in simulation models to evaluate various available alternatives considering physical, economic and environmental constraints. Improvements on feed material and operation, competitive energy market, environmental restrictions and the role of Nordic steelworks as energy supplier (electricity and district heat) make a great motivation behind integration among industries toward more sustainable operation, which could increase the overall energy efficiency and decrease environmental impacts. In this study, through different steps a model is developed for primary steelmaking, with the Finnish steel sector as a reference, to evaluate future operation concepts of a steelmaking site regarding sustainability. The research started by potential study on increasing energy efficiency and carbon dioxide reduction due to integration of steelworks with chemical plants for possible utilization of available off-gases in the system as chemical products. These off-gases from blast furnace, basic oxygen furnace and coke oven furnace are mainly contained of carbon monoxide, carbon dioxide, hydrogen, nitrogen and partially methane (in coke oven gas) and have proportionally low heating value but are currently used as fuel within these industries. Nonlinear optimization technique is used to assess integration with methanol plant under novel blast furnace technologies and (partially) substitution of coal with other reducing agents and fuels such as heavy oil, natural gas and biomass in the system. Technical aspect of integration and its effect on blast furnace operation regardless of capital expenditure of new operational units are studied to evaluate feasibility of the idea behind the research. Later on the concept of polygeneration system added and a superstructure generated with alternative routes for off-gases pretreatment and further utilization on a polygeneration system producing electricity, district heat and methanol. (Vacuum) pressure swing adsorption, membrane technology and chemical absorption for gas separation; partial oxidation, carbon dioxide and steam methane reforming for methane gasification; gas and liquid phase methanol synthesis are the main alternative process units considered in the superstructure. Due to high degree of integration in process synthesis, and optimization techniques, equation oriented modeling is chosen as an alternative and effective strategy to previous sequential modelling for process analysis to investigate suggested superstructure. A mixed integer nonlinear programming is developed to study behavior of the integrated system under different economic and environmental scenarios. Net present value and specific carbon dioxide emission is taken to compare economic and environmental aspects of integrated system respectively for different fuel systems, alternative blast furnace reductants, implementation of new blast furnace technologies, and carbon dioxide emission penalties. Sensitivity analysis, carbon distribution and the effect of external seasonal energy demand is investigated with different optimization techniques. This tool can provide useful information concerning techno-environmental and economic aspects for decision-making and estimate optimal operational condition of current and future primary steelmaking under alternative scenarios. The results of the work have demonstrated that it is possible in the future to develop steelmaking towards more sustainable operation.
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We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 ± 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 ± 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 ± 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 ± 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 ± 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 ± 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain.
Resumo:
We investigated the effects of lead exposure during the pre- and postnatal period on the neurobehavioral development of female Wistar rats (70-75 days of age, 120-150 g) using a protocol of lead intoxication that does not affect weight gain. Wistar rats were submitted to lead acetate intoxication by giving their dams 1.0 mM lead acetate. Control dams received deionized water. Growth and neuromotor development were assessed by monitoring daily the following parameters in 20 litters: body weight, ear unfolding, incisor eruption, eye opening, righting, palmar grasp, negative geotaxis, cliff avoidance and startle reflex. Spontaneous alternation was assessed on postnatal day 17 using a T maze. The animals' ability to equilibrate on a beaker rim was measured on postnatal day 19. Lead intoxication was confirmed by measuring renal, hepatic and cerebral lead concentration in dams and litters. Lead treatment hastened the day of appearance of the following parameters: eye opening (control: 13.5 ± 0.6, N = 88; lead: 12.9 ± 0.6, N = 72; P<0.05), startle reflex (control: 13.0 ± 0.8, N = 88; lead: 12.0 ± 0.7, N = 72; P<0.05) and negative geotaxis. On the other hand, spontaneous alternation performance was hindered in lead-exposed animals (control: 37.6 ± 19.7; lead: 57.5 ± 28.3% of alternating animals; P<0.05). These results suggest that lead exposure without concomitant undernutrition alters rat development, affecting specific subsets of motor skills.