Double diffusive unsteady free convection on two-dimensional and axisymmetric bodies in a porous medium

The unsteady laminar free convection flow of an incompressible electrically conducting fluid over two-dimensional and axisymmetric bodies embedded in a highly porous medium with an applied magnetic field has been studied. The unsteadiness in the flow field is caused by the variation of the wall temperature and concentration with time. The coupled nonlinear partial differential equations with three independent variables have been solved numerically using an implicit finite-difference scheme in combination with the quasilinearization technique. It is observed that the skin friction, heat transfer and mass transfer increase with the permeability parameter but decrease with the magnetic parameter. The results are strongly dependent on the variation of wall temperature and concentration with time. The skin friction and heat transfer increase or decrease as the buoyancy forces from species diffusion assist or oppose the thermal buoyancy force. However, the mass transfer is found to be higher for small values of the ratio of the buoyancy parameters than for large values

Oxide-based bifunctional oxygen electrode for rechargeable metal/air batteries

Statistical methods for optimizing the morphology of oxide-based, bifunctional oxygen electrodes for use in rechargeable metal/air batteries are examined with regard to binder composition, compaction time, and compaction load. Results show that LaNiO3 with PTFE binder in a nickel mesh envelope provides a satisfactory electrode.

Unsteady mixed convection with double diffusion over a horizontal cylinder and a sphere within a porous medium

The combined effects of the permeability of the medium, magnetic field, buoyancy forces and dissipation on the unsteady mixed convection flow over a horizontal cylinder and a sphere embedded in a porous medium have been studied. The nonlinear coupled partial differential equations with three independent variables have been solved numerically using an implicit finite-difference scheme in combination with the quasilinearization technique. The skin friction, heat transfer and mass transfer increase with the permeability of the medium, magnetic field and buoyancy parameter. The heat and mass transfer continuously decrease with the stream-wise distance, whereas the skin friction increases from zero, attains a maximum and then decreases to zero. The skin friction, heat transfer and mass transfer are significantly affected by the free stream velocity distribution. The effect of dissipation parameter is found to be more pronounced on the heat transfer than on the skin friction and mass transfer

PVA-SSA-HPA Mixed-Matrix-Membrane Electrolytes for DMFCs

Stabilized forms of heteropolyacids (HPAs), namely phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), are incorporated into poly (vinyl alcohol) (PVA) cross-linked with sulfosuccinic acid (SSA) to form mixed-matrix membranes for application in direct methanol fuel cells (DMFCs). Bridging SSA between PVA molecules not only strengthens the network but also facilitates proton conduction in HPAs. The mixed-matrix membranes are characterized for their mechanical stability, sorption capability, ion-exchange capacity, and wetting in conjunction with their proton conductivity, methanol permeability, and DMFC performance. Methanol-release kinetics is studied ex situ by volume-localized NMR spectroscopy (employing point-resolved spectroscopy'') with the results clearly demonstrating that the incorporation of certain inorganic fillers in PVA-SSA viz., STA and PTA, retards the methanol-release kinetics under osmotic drag compared to Nafion, although PVA-SSA itself exhibits a still lower methanol permeability. The methanol crossover rate for PVA-SSA-HPA-bridged-mixed-matrix membranes decreases dramatically with increasing current density rendering higher DMFC performance in relation to a DMFC using a pristine PVA-SSA membrane. A peak power density of 150 mW/cm(2) at a load current density of 500 mA/cm(2) is achieved for the DMFC using a PVA-SSA-STA-bridged-mixed-matrix-membrane electrolyte. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3465653] All rights reserved.

Effect of mechanical treatment on the reactivity of ammonium perchlorate

Thermal reactivities of ammonium perchlorate (AP) pressed at 1500 kg cm–2 for various dwell times ranging from 0 to 45 min have been investigated. Reactivity of AP is observed to (a) increase with increase of dwell time up to 15 min and (b) decrease for the compacts obtained at higher dwell times. X-ray diffraction profiles of the compacts indicated a broadening up to 15 min dwell time and a narrowing thereafter. The increase in the reactivity has been attributed to the increase in the number of gross imperfections and plastic deformation of particles. The decrease in the reactivity is explained in terms of recrystallization after plastic deformation. Local heating is shown to exist during compaction though its macroscopic effect is insignificant during compaction of AP.

Interrelations between Dry Eye Syndrome and Tear Fluid Phospholipid Transfer Protein

The simplified model of human tear fluid (TF) is a three-layered structure composed of a homogenous gel-like layer of hydrated mucins, an aqueous phase, and a lipid-rich outermost layer found in the tear-air interface. It is assumed that amphiphilic phospholipids are found adjacent to the aqueous-mucin layer and externally to this a layer composed of non-polar lipids face the tear-air interface. The lipid layer prevents evaporation of the TF and protects the eye, but excess accumulation of lipids may lead to drying of the corneal epithelium. Thus the lipid layer must be controlled and maintained by some molecular mechanisms. In the circulation, phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) mediate lipid transfers. The aim of this thesis was to investigate the presence and molecular mechanisms of lipid transfer proteins in human TF. The purpose was also to study the role of these proteins in the development of dry eye syndrome (DES). The presence of TF PLTP and CETP was studied by western blotting and mass spectrometry. The concentration of these proteins was determined by ELISA. The activities of the enzymes were determined by specific lipid transfer assays. To study the molecular mechanisms involved in PLTP mediated lipid transfer Langmuir monolayers and asymmetrical flow field-flow fractionation (AsFlFFF) was used. Ocular tissue samples were stained with monoclonal antibodies against PLTP to study the secretion route of PLTP. Heparin-Sepharose affinity chromatography was used for PLTP pull-down experiments and co-eluted proteins were identified with MALDI-TOF mass spectrometry or Western blot analysis. To study whether PLTP plays any functional role in TF PLTP-deficient mice were examined. The activity of PLTP was also studied in dry eye patients. PLTP is a component of normal human TF, whereas CETP is not. TF PLTP concentration was about 2-fold higher than that in human plasma. Inactivation of PLTP by heat treatment or immunoinhibition abolished the phospholipid transfer activity in tear fluid. PLTP was found to be secreted from lacrimal glands. PLTP seems to be surface active and is capable of accepting lipid molecules without the presence of lipid-protein complexes. The active movement of radioactively labeled lipids and high activity form of PLTP to acceptor particles suggested a shuttle model of PLTP-mediated lipid transfer. In this model, PLTP physically transports lipids between the donor and acceptor. Protein-protein interaction assays revealed ocular mucins as PLTP interaction partners in TF. In mice with a full deficiency of functional PLTP enhanced corneal epithelial damage, increased corneal permeability to carboxyfluorescein, and decreased corneal epithelial occludin expression was demonstrated. Increased tear fluid PLTP activity was observed among human DES patients. These results together suggest a scavenger property of TF PLTP: if the corneal epithelium is contaminated by hydrophobic material, PLTP could remove them and transport them to the superficial layer of the TF or, alternatively, transport them through the naso-lacrimal duct. Thus, PLTP might play an integral role in tear lipid trafficking and in the protection of the corneal epithelium. The increased PLTP activity in human DES patients suggests an ocular surface protective role for this lipid transfer protein.

Fractional-factorial design of a porous-carbon fuel-cell electrode

The use of fractional-factorial methods in the optimization of porous-carbon electrode structure is discussed with respect to weight-loss of carbon during gas treatment, weight and mixing time of binder, compaction temperature, time and pressure, and pressure of feed gas. The experimental optimization of an air electrode in alkaline solution is described.

Interaction of rat testis protein, TP, with nucleosome core particle

Circular dichroism studies have revealed that addition of testis specific protein, TP in vitro, to rat testes nucleosome core particle resulted in a decrease in the compaction of the core particle DNA. This was also corroborated by thermal denaturation analysis. Addition of TP to nucleosome core particle resulted in the conversion of a biphasic transition towards a single phase. However, at the same time there was a 20% reduction in the overall hyperchromicity of core particle DNA at core particle to TP molar ratios of 1:2 and 1:3. These observations along with our earlier report, showing the DNA melting properties of TP, suggest that TP may play an important role in the disassembly process of nucleosome core particle during spermiogenesis.

Studies on high‐density nickel zinc ferrite and its magnetic properties using novel hydrazine precursors

Nickel zinc ferrites have been very widely used in the high‐frequency applications. In our present study we have prepared Ni1−x Znx Fe2O4 (0≤x≤1) using novel hydrazinium metal hydrazinecarboxylate precursors. High densities (∼99%) have been obtained for all the ferrites sintered at relatively low temperatures, 1100 °C, in comparison with the conventional method (≥1200 °C). The variation of magnetic properties like magnetic moment, Curie temperature, and permeability with zinc concentration have been studied.

Ultrafine Mn---Zn ferrites: Preparation and properties

High density Mn-Zr ferrites have been extensively used in recording head applications. The properties like permeability, los~, etc., depend on the preparation method. The :roperfies play major role in selecting these materials for various applications.In this present work., we have prepared Mn-Zn ferrites musing metal hydrazine carboxylate precursors (N2Hs)3Mn0.sZn0.sFe2(N2H3COO)3"3H20. The precursor decomposes at very low temperature (~250°C) to form ultrafine Mno.sZn0.sFe204. The partic~,e size permeability spectrum, microstructure and magnetic properties will be discussed in this paper.

Hantavirus glycoprotein GN in virion assembly and regulation of interferon response

Hantaviruses have a tri-segmented negative-stranded RNA genome. The S segment encodes the nucleocapsid protein (N), M segment two glycoproteins, Gn and Gc, and the L segment the RNA polymerase. Gn and Gc are co-translationally cleaved from a precursor and targeted to the cis-Golgi compartment. The Gn glycoprotein consists of an external domain, a transmembrane domain and a C-terminal cytoplasmic domain. In addition, the S segment of some hantaviruses, including Tula and Puumala virus, have an open reading frame (ORF) encoding a nonstructural potein NSs that can function as a weak interferon antagonist. The mechanisms of hantavirus-induced pathogenesis are not fully understood but it is known that both hemorrhagic fever with renal syndrome (HFRS) and hantavirus (cardio) pulmonary syndrome (HCPS) share various features such as increased capillary permeability, thrombocytopenia and upregulation of TNF-. Several hantaviruses have been reported to induce programmed cell death (apoptosis), such as TULV-infected Vero E6 cells which is known to be defective in interferon signaling. Recently reports describing properties of the hantavirus Gn cytoplasmic tail (Gn-CT) have appeared. The Gn-CT of hantaviruses contains animmunoreceptor tyrosine-based activation motif (ITAM) which directs receptor signaling in immune and endothelial cells; and contain highly conserved classical zinc finger domains which may have a role in the interaction with N protein. More functions of Gn protein have been discovered, but much still remains unknown. Our aim was to study the functions of Gn protein from several aspects: synthesis, degradation and interaction with N protein. Gn protein was reported to inhibit interferon induction and amplication. For this reason, we also carried out projects studying the mechanisms of IFN induction and evasion by hantavirus. We first showed degradation and aggresome formation of the Gn-CT of the apathogenic TULV. It was reported earlier that the degradation of Gn-CT is related to the pathogenicity of hantavirus. We found that the Gn-CT of the apathogenic hantaviruses (TULV, Prospect Hill virus) was degraded through the ubiquitin-proteasome pathway, and TULV Gn-CT formed aggresomes upon treatment with proteasomal inhibitor. Thus the results suggest that degradation and aggregation of the Gn-CT may be a general property of most hantaviruses, unrelated to pathogenicity. Second, we investigated the interaction of TULV N protein and the TULV Gn-CT. The Gn protein is located on the Golgi membrane and its interaction with N protein has been thought to determine the cargo of the hantaviral ribonucleoprotein which is an important step in virus assembly, but direct evidence has not been reported. We found that TULV Gn-CT fused with GST tag expressed in bacteria can pull-down the N protein expressed in mammalian cells; a mutagenesis assay was carried out, in which we found that the zinc finger motif in Gn-CT and RNA-binding motif in N protein are indispensable for the interaction. For the study of mechanisms of IFN induction and evasion by Old World hantavirus, we found that Old World hantaviruses do not produce detectable amounts of dsRNA in infected cells and the 5 -termini of their genomic RNAs are monophosphorylated. DsRNA and tri-phosphorylated RNA are considered to be critical activators of innate immnity response by interacting with PRRs (pattern recognition receptors). We examined systematically the 5´-termini of hantavirus genomic RNAs and the dsRNA production by different species of hantaviruses. We found that no detectable dsRNA was produced in cells infected by the two groups of the old world hantaviruses: Seoul, Dobrava, Saaremaa, Puumala and Tula. We also found that the genomic RNAs of these Old World hantaviruses carry 5´-monophosphate and are unable to trigger interferon induction. The antiviral response is mainly mediated by alpha/beta interferon. Recently the glycoproteins of the pathogenic hantaviruses Sin Nombre and New York-1 viruses were reported to regulate cellular interferon. We found that Gn-CT can inhibit the induction of IFN activation through Toll-like receptor (TLR) and retinoic acid-inducible gene I-like RNA helicases (RLH) pathway and that the inhibition target lies at the level of TANK-binding kinase 1 (TBK-1)/ IKK epislon complex and myeloid differentiation primary response gene (88) (MyD88) / interferon regulatory factor 7 (IRF-7) complex.

Sarveiskalvon permeabiliteetin ennustaminen QSPR-mallin avulla

QSPR-malli kuvaa kvantitatiivista riippuvuutta muuttujien ja biologisen ominaisuuden välillä. Näin ollen QSPR mallit ovat käyttökelpoisia lääkekehityksen apuvälineitä. Kirjallisessa osassa kerrotaan sarveiskalvon, suoliston ja veriaivoesteen permeabiliteetin malleista. Useimmin käytettyjä muuttujia ovat yhdisteen rasvaliukoisuus, polaarinen pinta-ala, vetysidosten muodostuminen ja varaus. Myös yhdisteen koko vaikuttaa läpäisevyyteen, vaikka tutkimuksissa onkin erilaista tietoa tämän merkittävyydestä. Malliin vaikuttaa myös muiden kuin mallissa mukana olevien muuttujien suuruusluokka esimerkkinä Lipinskin ‖rule of 5‖ luokittelu. Tässä luokittelussa yhdisteen ominaisuus ei saa ylittää tiettyjä raja-arvoja. Muussa tapauksessa sen imeytyminen suun kautta otettuna todennäköisesti vaarantuu. Lisäksi kirjallisessa osassa tutustuttiin kuljetinproteiineihin ja niiden toimintaan silmän sarveiskalvossa, suolistossa ja veriaivoesteessä. Nykyisin on kehitetty erilaisia QSAR-malleja kuljetinproteiineille ennustamaan mahdollisten substraatittien tai inhibiittorien vuorovaikutuksia kuljetinproteiinin kanssa. Kokeellisen osan tarkoitus oli rakentaa in silico -malli sarveiskalvon passiiviselle permeabiliteetille. Työssä tehtiin QSPR-malli 54 yhdisteen ACDLabs-ohjelmalla laskettujen muuttujien arvojen avulla. Permeabiliteettikertoimien arvot saatiin kirjallisuudesta kanin sarveiskalvon läpäisevyystutkimuksista. Lopullisen mallin muuttujina käytettiin oktanoli-vesijakaantumiskerrointa (logD) pH:ssa 7,4 ja vetysidosatomien kokonaismäärää. Yhtälö oli muotoa log10(permeabiliteettikerroin) = -3,96791 - 0,177842Htotal + 0,311963logD(pH7,4). R2-korrelaatiokerroin oli 0,77 ja Q2-korrelaatiokerroin oli 0,75. Lopullisen mallin hyvyyttä arvioitiin 15 yhdisteen ulkoisella testijoukolla, jolloin ennustettua permeabiliteettia verrattiin kokeelliseen permeabiliteettiin. QSPR-malli arvioitiin myös farmakokineettisen simulaation avulla. Simulaatiossa laskettiin seitsemän yhdisteen kammionestepitoisuudet in vivo vakaassa tilassa käyttäen simulaatioissa QSPR mallilla ennustettuja permeabiliteettikertoimia. Lisäksi laskettiin sarveiskalvon imeytymisen nopeusvakio (Kc) 13 yhdisteelle farmakokineettisen simulaation avulla ja verrattiin tätä lopullisella mallilla ennustettuun permeabiliteettiin. Tulosten perusteella saatiin tilastollisesti hyvä QSPR-malli kuvaamaan sarveiskalvon passiivista permeabiliteettia, jolloin tätä mallia voidaan käyttää lääkekehityksen alkuvaiheessa. QSPR-malli ennusti permeabiliteettikertoimet hyvin, mikä nähtiin vertaamalla mallilla ennustettuja arvoja kokeellisiin tuloksiin. Lisäksi yhdisteiden kammionestepitoisuudet voitiin simuloida käyttäen apuna QSPR-mallilla ennustettuja permeabiliteettikertoimien arvoja.

Wood and fiber properties of Norway spruce and its suitability for thermomechanical pulping.

In the first part of the study, the selected wood and fiber properties were investigated in terms of their occurrence and variation in wood, as well as their relevance from the perspective of thermomechanical pulping process and related end-products. It was concluded that the most important factors were the fiber dimensions, juvenile wood content, and in some cases, the content of heartwood being associated with extremely dry wood with low permeability in spruce. With respect to the above properties, the following three pulpwood assortments of which pulping potential was assumed to vary were formed: wood from regeneration cuttings, first-thinnings wood, and sawmill chips. In the experimental part of the study the average wood and fiber characteristics and their variation were determined for each raw material group prior to pulping. Subsequently, each assortment - equaling about 1500 m3 roundwood - was pulped separately for a 24 h period, at constant process conditions. The properties of obtained newsgrade thermomechanical pulps were then determined. Thermomechanical pulping (TMP) from sawmill chips had the highest proportion of long fibers, smallest proportion of fines, and had generally the coarsest and longest fibers. TMP from first-thinnings wood was just the opposite, whereas that from regeneration cuttings fell in between the above two extremes. High proportion of dry heartwood in wood originating from regeneration cuttings produced a slightly elevated shives content. However, no differences were found in pulp specific energy consumption. The obtained pulp tear index was clearly best in TMP made from sawmill chips and poorest in pulp from first-thinnings wood, which had generally inferior strength properties. No dramatical differences in any of the strength properties were found between pulp from sawmill residual wood and regeneration cuttings. Pulp optical properties were superior in TMP from first-thinnings. Unexpectedly, no noticeable differences, which could be explained with fiber morphology, were found in sheet density, bulk, air permeance or roughness between the three pulps. The most important wood quality factors in this study were the fiber length, fiber cross-sectional dimensions and percentage juvenile wood. Differences found in the quality of TMP manufactured from the above spruce assortments suggest that they could be segregated and pulped separately to obtain specific product characteristics, i.e., for instance tailor-made end-products, and to minimize unnecessary variation in the raw material quality, and hence, pulp quality.

Mesoporous silica- and silicon-based materials as carriers for poorly water soluble drugs

New chemical entities with unfavorable water solubility properties are continuously emerging in drug discovery. Without pharmaceutical manipulations inefficient concentrations of these drugs in the systemic circulation are probable. Typically, in order to be absorbed from the gastrointestinal tract, the drug has to be dissolved. Several methods have been developed to improve the dissolution of poorly soluble drugs. In this study, the applicability of different types of mesoporous (pore diameters between 2 and 50 nm) silicon- and silica-based materials as pharmaceutical carriers for poorly water soluble drugs was evaluated. Thermally oxidized and carbonized mesoporous silicon materials, ordered mesoporous silicas MCM-41 and SBA-15, and non-treated mesoporous silicon and silica gel were assessed in the experiments. The characteristic properties of these materials are the narrow pore diameters and the large surface areas up to over 900 m²/g. Loading of poorly water soluble drugs into these pores restricts their crystallization, and thus, improves drug dissolution from the materials as compared to the bulk drug molecules. In addition, the wide surface area provides possibilities for interactions between the loaded substance and the carrier particle, allowing the stabilization of the system. Ibuprofen, indomethacin and furosemide were selected as poorly soluble model drugs in this study. Their solubilities are strongly pH-dependent and the poorest (< 100 µg/ml) at low pH values. The pharmaceutical performance of the studied materials was evaluated by several methods. In this work, drug loading was performed successfully using rotavapor and fluid bed equipment in a larger scale and in a more efficient manner than with the commonly used immersion methods. It was shown that several carrier particle properties, in particular the pore diameter, affect the loading efficiency (typically ~25-40 w-%) and the release rate of the drug from the mesoporous carriers. A wide pore diameter provided easier loading and faster release of the drug. The ordering and length of the pores also affected the efficiency of the drug diffusion. However, these properties can also compensate the effects of each other. The surface treatment of porous silicon was important in stabilizing the system, as the non-treated mesoporous silicon was easily oxidized at room temperature. Different surface chemical treatments changed the hydrophilicity of the porous silicon materials and also the potential interactions between the loaded drug and the particle, which further affected the drug release properties. In all of the studies, it was demonstrated that loading into mesoporous silicon and silica materials improved the dissolution of the poorly soluble drugs as compared to the corresponding bulk compounds (e.g. after 30 min ~2-7 times more drug was dissolved depending on the materials). The release profile of the loaded substances remained similar also after 3 months of storage at 30°C/56% RH. The thermally carbonized mesoporous silicon did not compromise the Caco-2 monolayer integrity in the permeation studies and improved drug permeability was observed. The loaded mesoporous silica materials were also successfully compressed into tablets without compromising their characteristic structural and drug releasing properties. The results of this research indicated that mesoporous silicon/silica-based materials are promising materials to improve the dissolution of poorly water soluble drugs. Their feasibility in pharmaceutical laboratory scale processes was also confirmed in this thesis.

Tumorigenesis in celiac disease

Celiac disease is life-long autoimmune disorder of the small intestine, which is caused by a reaction to gliadin found in wheat, rye and barley in genetically predisposed individuals. Proline- and glutamine -rich proteins cause villous atrophy and crypt hyperplasia with extensive inflammation in the epithelium and lamina propria. Symptoms of celiac disease vary considerably and elimination of gluten from diet is the only way to treat disease. In small intestine of celiac disease patient transglutaminase 2 (TG2) modifies gluten peptides, which causes T-cell activation and inflammation in the epithelium of mucosa. T-cell activation induces development of celiac disease specific antibodies. These celiac disease specific antibodies recognise TG2 and interfere in vitro and in vivo in angiogenesis. Abnormal angiogenesis is typical in many disorders, such in cancer, in which TG2 has a crucial role in the development and growth of tumor. Overexpression of TG2 has been shown to correlate with accelerated growth of tumor. TG2-specific antibodies are suggested to inhibit differentation of epithelial cell, increase their proliferation, decrease their barrier-function and increase the permeability of blood vessels. The aims of the pilot study were to establish whether celiac disease TG2 antibodies affect in vivo tumorigenesis and tumorangiogenesis as well as to try to clarify the mechanism behind the phenomenon. Tumor xenograft model was used in severe combined immunodeficient (SCID) mice. Human oesophageal carcinoma (OE-19) cancer cells were incubated with celiacs TG2 miniautoantibody (mini 2.8), non-celiac miniautoantibody (mini 6.2) or PBS before cancer cells were injected to mice subcutaneously. During the experiment mice were weighted and tumor size was measured couple of times per week. To estimate the volumes of tumors the following formula was used: π/6 * L* W* H. Experiment lasted for four weeks after which the mice were euthanized, cardiac blood and tissue samples taken and tumours were excised and weighted. Sections were made from tumors and immunohistochemical stainings were done to compare blood vessel areas and to study general tumors´morphology and other parameters. Western blot -analyse were performed to cancer cells. The masses and volumes were clearly smaller in mini 2.8-group compared to control groups and the necrotic area of tumor in mini 2.8 was smallest as percentage compared to control groups. Blood vessel area were smallest in mini 2.8 group. Results suggest that celiac disease anti-TG2-autoantibodies inhibit tumor growth, but the number of animals is insufficient to give an accurate outcome.