Ontogenesis of stomata in Velloziaceae: paracytic versus tetracytic?

In Velloziaceae, the number of subsidiary cells has been used to characterize species and support groups. Nevertheless, the homology of the stomatal types have not been scrutinized. Stomatal ontogenesis of Vellozia epidendroides and V. plicata, assigned to have tetracytic stomata, and of V. glauca and Barbacenia riparia, assigned to have paracytic stomata, were investigated. In the four species studied, stomata followed perigenic development. Subsidiary cells arise from oblique divisions of neighbouring cells of the guard mother cell (GMC). These cells are elongated and parallel to the longer axis of the stoma. Polar cells show wide variation, following the shape and size of the epidermal cells in the vicinity. Hence, these cells cannot be called subsidiary cells. This wide variation is due to a much higher density of stomata in some regions of the leaf blade. This distribution of stomata forces the development of short polar cells, leading to an apparently tetracytic stomata. In regions of low concentration of stomata, higher spatial availability between the GMCs allows the elongation of polar cells, leading to evident paracytic stomata. Therefore, the four studied species are considered braquiparacytic, questioning the classification of stomata into tetracytic and paracytic in Velloziaceae.

Anatomy, ultrastructure and secretion of Hibiscus pernambucensis Arruda (Malvaceae) extrafloral nectary

This paper reports on the extrafloral nectary (EFN) of Hibiscus pernambucensis, a native shrub species occurring in mangrove and restinga along Brazil's coastline. EFNs occur as furrows with a protuberant border on the abaxial surface veins of the leaf blade. Each nectary consists of numerous secretory multicellular trichomes, epidermal cells in palisade-like arrangements and non-vascularized parenchyma tissue. Nectar secretion is prolonged, since secretion starts in very young leaves and remains up to completely expanded leaves. Reduced sugars, lipids, and proteins were histochemically detected in all the nectary cells; phenolic substances were detected in the vacuoles of the epidermal palisade cells and in some secretory trichome cells. The secretory cells that constitute the body of trichomes have large nuclei, dense cytoplasm with numerous mitochondria, dictyosomes, scattered lipid droplets and plastids with different inclusions: protein, lipid droplets or starch grains; vacuoles with different sizes have membranous material, phenolic and lipophilic substances. The palisade cells show thick periclinal walls, reduced cytoplasm with voluminous lipid drops and developed vacuoles. The nectary parenchyma cells contain abundant plasmodesmata and cytoplasm with scattered lipid droplets, mitochondria, plastids with starch grains and endoplasmic reticulum. Mucilage idioblasts are common in the inner nectary parenchyma. Protoderm and ground meristem participate in the formation of EFN. Our data indicate that all nectary regions are involved in nectar production and secretion, constituting a functional unit. Longevity of the extrafloral nectaries is likely associated with the presence of mucilage idioblasts, which increases the capacity of the nectary parenchyma to store water.

Increased angiotensin-converting enzyme activity in the left ventricle after infarction

An increase in angiotensin-converting enzyme (ACE) activity has been observed in the heart after myocardial infarction (MI). Since most studies have been conducted in chronically infarcted individuals exhibiting variable degrees of heart failure, the present study was designed to determine ACE activity in an earlier phase of MI, before heart failure development. MI was produced in 3-month old male Wistar rats by ligation of the anterior branches of the left coronary artery, control rats underwent sham surgery and the animals were studied 7 or 15 days later. Hemodynamic data obtained for the anesthetized animals showed normal values of arterial blood pressure and of end-diastolic pressure in the right and left ventricular cavities of MI rats. Right and left ventricular (RV, LV) muscle and scar tissue homogenates were prepared to determine ACE activity in vitro by measuring the velocity of His-Leu release from the synthetic substrate Hyp-His-Leu. ACE activity was corrected to the tissue wet weight and is reported as nmol His-Leu g-1 min-1. No significant change in ACE activity in the RV homogenates was demonstrable. A small nonsignificant increase of ACE activity (11 &plusmn; 9%; P0.05) was observed 7 days after MI in the surviving left ventricular muscle. Two weeks after surgery, however, ACE activity was 46 &plusmn; 11% (P<0.05) higher in infarcted rats compared to sham-operated rats. The highest ACE activity was demonstrable in the scar tissue homogenate. In rats studied two weeks after surgery, ACE activity in the LV muscle increased from 105 &plusmn; 7 nmol His-Leu g-1 min-1 in control hearts to 153 &plusmn; 11 nmol His-Leu g-1 min-1 (P<0.05) in the remaining LV muscle of MI rats and to 1051 &plusmn; 208 nmol His-Leu g-1 min-1 (P<0.001) in the fibrous scar. These data indicate that ACE activity increased in the heart after infarction before heart failure was demonstrable by hemodynamic measurements. Since the blood vessels of the scar drain to the remaining LV myocardium, the high ACE activity present in the fibrous scar may increase the angiotensin II concentration and decrease bradykinin in the cardiac tissues surrounding the infarcted area. The increased angiotensin II in the fibrous scar may contribute to the reactive fibrosis and hypertrophy in the left ventricular muscle surviving infarction

Working fluid selection and design of small-scale waste heat recovery systems based on organic Rankine cycles

Demand for the use of energy systems, entailing high efficiency as well as availability to harness renewable energy sources, is a key issue in order to tackling the threat of global warming and saving natural resources. Organic Rankine cycle (ORC) technology has been identified as one of the most promising technologies in recovering low-grade heat sources and in harnessing renewable energy sources that cannot be efficiently utilized by means of more conventional power systems. The ORC is based on the working principle of Rankine process, but an organic working fluid is adopted in the cycle instead of steam. This thesis presents numerical and experimental results of the study on the design of small-scale ORCs. Two main applications were selected for the thesis: waste heat re- covery from small-scale diesel engines concentrating on the utilization of the exhaust gas heat and waste heat recovery in large industrial-scale engine power plants considering the utilization of both the high and low temperature heat sources. The main objective of this work was to identify suitable working fluid candidates and to study the process and turbine design methods that can be applied when power plants based on the use of non-conventional working fluids are considered. The computational work included the use of thermodynamic analysis methods and turbine design methods that were based on the use of highly accurate fluid properties. In addition, the design and loss mechanisms in supersonic ORC turbines were studied by means of computational fluid dynamics. The results indicated that the design of ORC is highly influenced by the selection of the working fluid and cycle operational conditions. The results for the turbine designs in- dicated that the working fluid selection should not be based only on the thermodynamic analysis, but requires also considerations on the turbine design. The turbines tend to be fast rotating, entailing small blade heights at the turbine rotor inlet and highly supersonic flow in the turbine flow passages, especially when power systems with low power outputs are designed. The results indicated that the ORC is a potential solution in utilizing waste heat streams both at high and low temperatures and both in micro and larger scale appli- cations.

Effect of epithelial debridement on human cornea proteoglycans

Corneal transparency is attributed to the regular spacing and diameter of collagen fibrils, and proteoglycans may play a role in fibrillogenesis and matrix assembly. Corneal scar tissue is opaque and this opacity is explained by decreased ultrastructural order that may be related to proteoglycan composition. Thus, the objectives of the present study were to characterize the proteoglycans synthesized by human corneal explants and to investigate the effect of mechanical epithelial debridement. Human corneas unsuitable for transplants were immersed in F-12 culture medium and maintained under tissue culture conditions. The proteoglycans synthesized in 24 h were labeled metabolically by the addition of 35S-sulfate to the medium. These compounds were extracted by 4 M GuHCl and identified by a combination of agarose gel electrophoresis, enzymatic degradation with protease and mucopolysaccharidases, and immunoblotting. Decorin was identified as the main dermatan sulfate proteoglycan and keratan sulfate proteoglycans were also prominent components. When the glycosaminoglycan side chains were analyzed, only keratan sulfate and dermatan sulfate were detected (~50% each). Nevertheless, when these compounds were 35S-labeled metabolically, the label in dermatan sulfate was greater than in keratan sulfate, suggesting a lower synthesis rate for keratan sulfate. 35S-Heparan sulfate also appeared. The removal of the epithelial layer caused a decrease in heparan sulfate labeling and induced the synthesis of dermatan sulfate by the stroma. The increased deposit of dermatan sulfate proteoglycans in the stroma suggests a functional relationship between epithelium and stroma that could be related to the corneal opacity that may appear after epithelial cell debridement.

Schwann cells for spinal cord repair

The complex nature of spinal cord injury appears to demand a multifactorial repair strategy. One of the components that will likely be included is an implant that will fill the area of lost nervous tissue and provide a growth substrate for injured axons. Here we will discuss the role of Schwann cells (SCs) in cell-based, surgical repair strategies of the injured adult spinal cord. We will review key studies that showed that intraspinal SC grafts limit injury-induced tissue loss and promote axonal regeneration and myelination, and that this response can be improved by adding neurotrophic factors or anti-inflammatory agents. These results will be compared with several other approaches to the repair of the spinal cord. A general concern with repair strategies is the limited functional recovery, which is in large part due to the failure of axons to grow across the scar tissue at the distal graft-spinal cord interface. Consequently, new synaptic connections with spinal neurons involved in motor function are not formed. We will highlight repair approaches that did result in growth across the scar and discuss the necessity for more studies involving larger, clinically relevant types of injuries, addressing this specific issue. Finally, this review will reflect on the prospect of SCs for repair strategies in the clinic.

Hypoglycemic activity of polysaccharide fractions containing ß-glucans from extracts of Rhynchelytrum repens (Willd.) C.E. Hubb., Poaceae

ß-Glucans are soluble fibers with physiological functions, such as interference with absorption of sugars and reduction of serum lipid levels. The objective of the present study was to analyze the distribution of ß-glucans in different tissues of the African grass species Rhynchelytrum repens and also to evaluate their hypoglycemic activity. Leaf blades, sheaths, stems, and young leaves of R. repens were submitted to extraction with 4 M KOH. Analysis of the fractions revealed the presence of arabinose, glucose, xylose, and traces of rhamnose and galactose. The presence of ß-glucan in these fractions was confirmed by hydrolyzing the polymers with endo-ß-glucanase from Bacillus subtilis, followed by HPLC analysis of the characteristic oligosaccharides produced. The 4 M KOH fractions from different tissues were subjected to gel permeation chromatography on Sepharose 4B, with separation of polysaccharides with different degrees of polymerization, the highest molecular mass (above 2000 kDa) being found in young leaves. The molecular mass of the leaf blade polymers was similar (250 kDa) to that of maize coleoptile ß-glucan used for comparison. The 4 M KOH fraction injected into rats with streptozotocin-induced diabetes showed hypoglycemic activity, reducing blood sugar to normal levels for approximately 24 h. This performance was better than that obtained with pure ß-glucan from barley, which decreased blood sugar levels for about 4 h. These results suggest that the activity of ß-glucans from R. repens is responsible for the use of this plant extract as a hypoglycemic drug in folk medicine.

Translational models of coronary artery disease, myocardial infarction and heart failure. Development, validation and in vivo imaging studies using positron emission tomography

Coronary artery disease is an atherosclerotic disease, which leads to narrowing of coronary arteries, deteriorated myocardial blood flow and myocardial ischaemia. In acute myocardial infarction, a prolonged period of myocardial ischaemia leads to myocardial necrosis. Necrotic myocardium is replaced with scar tissue. Myocardial infarction results in various changes in cardiac structure and function over time that results in “adverse remodelling”. This remodelling may result in a progressive worsening of cardiac function and development of chronic heart failure. In this thesis, we developed and validated three different large animal models of coronary artery disease, myocardial ischaemia and infarction for translational studies. In the first study the coronary artery disease model had both induced diabetes and hypercholesterolemia. In the second study myocardial ischaemia and infarction were caused by a surgical method and in the third study by catheterisation. For model characterisation, we used non-invasive positron emission tomography (PET) methods for measurement of myocardial perfusion, oxidative metabolism and glucose utilisation. Additionally, cardiac function was measured by echocardiography and computed tomography. To study the metabolic changes that occur during atherosclerosis, a hypercholesterolemic and diabetic model was used with [18F] fluorodeoxyglucose ([18F]FDG) PET-imaging technology. Coronary occlusion models were used to evaluate metabolic and structural changes in the heart and the cardioprotective effects of levosimendan during post-infarction cardiac remodelling. Large animal models were used in testing of novel radiopharmaceuticals for myocardial perfusion imaging. In the coronary artery disease model, we observed atherosclerotic lesions that were associated with focally increased [18F]FDG uptake. In heart failure models, chronic myocardial infarction led to the worsening of systolic function, cardiac remodelling and decreased efficiency of cardiac pumping function. Levosimendan therapy reduced post-infarction myocardial infarct size and improved cardiac function. The novel 68Ga-labeled radiopharmaceuticals tested in this study were not successful for the determination of myocardial blood flow. In conclusion, diabetes and hypercholesterolemia lead to the development of early phase atherosclerotic lesions. Coronary artery occlusion produced considerable myocardial ischaemia and later infarction following myocardial remodelling. The experimental models evaluated in these studies will enable further studies concerning disease mechanisms, new radiopharmaceuticals and interventions in coronary artery disease and heart failure.

Effects of strain and age on ear wound healing and regeneration in mice

Round holes in the ears of MRL mice tend to close with characteristics of regeneration believed to be absent in other mouse strains (e.g., C57BL/6). We evaluated the kinetics and the histopathology of ear wound closure in young (8 weeks old) C57BL/6 and BALB/c mice. We also used middle-aged (40 weeks old) C57BL/6 mice to evaluate the influence of aging on this process. A circular through-and-through hole was made in the ear, photographs were taken at different times after injury and wound area was measured with digital analysis software. The percentages of closed area measured on day 100 were: 23.57 ± 8.66% for young BALB/c mice, 56.47 ± 7.39% for young C57BL/6 mice, and 75.31 ± 23.65% for middle-aged C57BL/6 mice. Mice were sacrificed on days 1, 3, 5, 25, 44, and 100 for histological evaluation with hematoxylin and eosin, Gomori’s trichrome, periodic acid-Schiff, or picrosirius red staining. In young mice of both strains, healing included re-epithelialization, chondrogenesis, myogenesis, and collagen deposition. Young C57BL/6 and BALB/c mice differed in the organization of collagen fibers visualized using picrosirius-polarization. Sebaceous glands and hair follicles regenerated and chondrogenesis was greater in young C57BL/6 mice. In middle-aged C57BL/6 mice all aspects of regeneration were depressed. The characteristics of regeneration were present during ear wound healing in both young BALB/c and young C57BL/6 mice although they differed in intensity and pattern. Greater ear wound closure in middle-aged C57BL/6 mice was not correlated with regeneration.

Prosessiteollisuuden sekoittimen elinkaariarviointi

Työn tavoitteena oli tehdä elinkaariarviointi (LCA) prosessiteollisuuden sekoittimelle Helmix HF-80 ja analysoida LCA-tulokset, vaikutus ilmaston lämpenemisen potentiaalin (GWP) suhteen, sekä tutkia GWP-vaikutuksen pienentämisen mahdollisuuksia. Tutkittavan sekoittimen mahdolliset käyttökohteet ovat sellu- ja paperiteollisuus, raskaiden jätenesteiden käsittely, sekä muut teollisuusalueet, joissa käytetään tämän tyyppisiä laitteita. Työssä on muun muassa käsitelty sekoitusprosessit, sekoituslaitteiden tyypit, niiden rakenteiden ominaisuudet, käyttötarkoitus, toimintaperiaatteet, sekä sellu- ja paperi-teollisuudessa käytettävien sekoittimien yleiskatsaus. Työssä on myös kuvattu elinkaariarviointi (LCA) -menetelmä ja sen käyttötarkoitus. Tärkeimmistä tuloksista voi mainita sen, että sekoittimen (ilman säiliötä, sähkömoottoria ja vaihteistoa) kokoelinkaaren ilmastonlämpenemisen potentiaali (GWP) on noin 750 000 kg CO2-Equiv. Sekoittimen tuotanto- ja kierrätysaikana syntyy vain 1200 kg CO2-Equiv. ja suurin osa 748 000 kg CO2-Equiv. johtuu sähköenergian kulutuksesta käytön aikana. Käyttöajan vaikutusta voisi pienentää arvoksi 0 kg CO2-Equiv. käyttämällä pelkästään uusiutuvaa energiaa. Jos tuotantoaikana käytetty energia myös korvataan uusiutuvalla energialla, niin GWP-arvo koko elinkaaren aikana laskee arvoon 1006 kg CO2eqv., mikä on vain 0,13 % saaduista tuloksista. Suurin osa tästä arvosta liittyy sekoittimen materiaalin, tässä tapauksessa ruostumattoman teräksen tuotantoon.

Synnytyksen ponnistusvaiheen hoidon käytännöt. Yhteys ensisynnyttäjän välilihan kuntoon synnytyksen jälkeen, synnytyskokemukseen, kipuun ja seksuaaliterveyteen

Hyvän syntymän hoidon tavoitteena on turvata synnyttäjän paras mahdollinen terveys, vähentää tarpeetonta puuttumista synnytyksen kulkuun ja mahdollistaa voimaannuttava synnytyskokemus perheelle. Hyvä syntymän hoito ja siihen liittyvä kätilöiden kliinisen hoitotyön osaaminen ei voi kehittyä, ellei hoitotyön käytäntöjä tutkita. Suomalaista hoitotieteellistä syntymän hoitoon liittyvää tutkimusta on vähän. Tämän tutkimuksen tarkoituksena oli kuvata synnytyksen ponnistusvaiheen hoidon käytäntöjä Suomen synnytyssairaaloissa. Lisäksi seurantatutkimuksen avulla selvitettiin, miten ensisynnyttäjät kokivat synnytyksen ponnistusvaiheen, sen aikana saamansa hoidon, ensisynnyttäjien synnytyskokemusta, kivun kokemista, vointia kolmena päivänä synnytyksen jälkeen sekä heidän seksuaaliterveyttään ensimmäisen vuoden aikana synnytyksen jälkeen. Tutkimuksen tavoitteena oli tuottaa tietoa, jonka avulla voidaan kehittää synnytyksen ponnistusvaiheen hoitoa ja lisätä tietoa synnyttäneiden naisten voinnista ja seksuaaliterveydestä. Tutkimuksen ensimmäinen osio toteutettiin poikkileikkaustutkimuksena (2009), johon osallistui Suomen synnytyssairaaloiden synnytysosastoilla työskentelevät kätilöt (N = 662). Tutkimuksen toinen osio toteutettiin seurantatutkimuksena (2009−2011), jossa oli neljä mittausajankohtaa: kolmantena päivänä synnytyksestä sekä kolmen, kuuden ja kahdentoista kuukauden kuluttua synnytyksestä. Tähän osioon osallistui spontaanisti alateitse yhden elävän lapsen (pää tarjoutuvana) synnyttäneet ensisynnyttäjät (N = 453) ja sikiön perätilan vuoksi suunnitellusti keisarileikatut ensisynnyttäjät (N = 84). Aineisto analysoitiin tilastollisin menetelmin. Tutkimustulosten mukaan osa kätilöiden käyttämistä synnytyksen ponnistusvaiheen hoitokäytännöistä ei ole näyttöön perustuvia. Synnytyssairaalan synnytyksen hoidon kulttuuri näyttää siirtyvän mallioppimisen kautta. Ensisynnyttäjät kokivat synnytyksen ponnistusvaiheen hoidon pääsääntöisesti myönteisenä. Alateitse synnyttäneillä ensisynnyttäjillä oli myönteisempi synnytyskokemus ja vähemmän kipua heti synnytyksen jälkeen ja kolmena synnytyksen jälkeisenä päivänä verrattuna keisarileikkauksella synnyttäneisiin ensisynnyttäjiin. Alateitse synnyttäneillä ensisynnyttäjillä kipu ja ompeleet eivät vaikuttaneet haitallisesti vastasyntyneen hoitoon tai imetykseen niin paljon kuin keisarileikkauksella synnyttäneillä ensisynnyttäjillä. Välilihan leikkaus-, repeämä- tai keisarileikkaushaavat olivat täysin parantuneet suurimmalla osalla naisista kolmen kuukauden kuluttua synnytyksestä. Yleisimpiä naisten kokemia oireita ensimmäisen vuoden aikana synnytyksestä olivat emättimen kostumisen vaikeus, yhdyntäkivut, peräpukamat sekä arpikudoksen kipu ja kiristys. Sukupuolinen halukkuus ja tyytyväisyys seksielämään olivat huonompaa ensimmäisen vuoden aikana synnytyksestä verrattuna aikaan ennen raskautta ja synnytystä. Synnytyksen aikaisella hoitotyöllä ja näyttöön perustuvalla synnytyksen ponnistusvaiheen hoidolla on suuri merkitys naisen synnytyskokemukseen, synnytyksen jälkeiseen vointiin ja seksuaaliterveyteen.

Droplet Deposition in the Last Stage of Steam Turbine

During the expansion of steam in turbine, the steam crosses the saturation line and hence subsequent turbine stages run under wet condition. The stages under wet condition run with low efficiency as compared to stages running with supersaturated steam and the life of the last stage cascade is reduced due to erosion. After the steam crosses the saturation line it does not condense immediately but instead it becomes supersaturated which is a meta-stable state and reversion of equilibrium results in the formation of large number of small droplets in the range of 0.05 - 1 μm. Although these droplets are small enough to follow the stream lines of vapor however some of the fog droplets are deposited on the blade surface. After deposition they coagulate into films and rivulets which are then drawn towards the trailing edge of the blade due to viscous drag of the steam. These large droplets in the range of radius 100 μm are accelerated by steam until they impact on the next blade row causing erosion. The two phenomenon responsible for deposition are inertial impaction and turbulent-diffusion. This work shall discuss the deposition mechanism in steam turbine in detail and numerically model and validate with practical data.

Diseña tu plan de mercadeo: Documento descargar

Bogotá Emprende

Diseña tu plan de mercadeo: Documento de preguntas y respuestas

Bogotá Emprende

Ajuste: Diseña tu plan de mercadeo: Documento de preguntas y respuestas: Consejos prácticos

Bogotá Emprende