Increasing Oxide Content Research Articles

Increased Inflammatory Mediators in Horses Naturally Infected with Trypanosoma vivax. A Preliminary Study

The aim of this study was to measure the levels of inflammatory mediators in serum from horses naturally infected with Trypanosoma vivax. Banked serum samples collected during a previously reported T. vivax natural infection were used to analyze proinflammatory cytokines such as interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NOx) levels. We evaluated 12 serum samples from horses from a farm in southern Brazil, four of which had parasitological and molecular diagnoses for T. vivax and presented with clinical signs of disease. Cytokines were assessed by quantitative sandwich enzyme-linked immunosorbent assay, and NOx was measured using the modified Griess method. Levels of IFN-γ, TNF-α, IL-1, IL-6, and NOx were increased in serum of infected animals compared to that in noninfected animals. Therefore, infection with T. vivax caused an increase in proinflammatory cytokines and nitric oxide content.

Increased Cytokine and Nitric Oxide Levels in Serum of Dogs Experimentally Infected with Rangelia vitalii

This study aimed to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NOx) in serum of dogs experimentally infected with Rangelia vitalii. Twelve female mongrel dogs were divided into 2 groups; group A (uninfected controls) composed by healthy dogs (n=5) and group B consisting of dogs inoculated with R. vitalii (n=7). Animals were monitored by blood smear examinations, which showed intraerythrocytic forms of the parasite on day 5 post-infection (PI). Blood samples were collected through the jugular vein on days 0, 10, and 20 PI to determine the serum levels of IFN-γ, TNF-α, IL-1, IL-6, and NOx. Cytokines were assessed by ELISA quantitative sandwich technique, and NOx was measured by the modified Griess method. Cytokine levels (IFN-γ, TNF-α, IL-1, and IL-6) were increased (P<0.01) in serum of infected animals. Serum levels of NOx were also increased on days 10 PI (P<0.01) and 20 PI (P<0.05) in infected animals. Therefore, the infection with R. vitalii causes an increase in proinflammatory cytokines and nitric oxide content. These alterations may be associated with host immune protection against the parasite.

Thermal stability of Ni/NiO multilayers

The effects of NiO multilayer additions to pulsed-laser deposited nanocrystalline Ni on the grain growth and texture evolution during annealing have been studied using a combination of in situ annealing in the transmission electron microscope and the recently developed transmission electron backscatter diffraction technique. Grain growth in pure Ni proceeds in an abnormal manner with a small number of grains growing rapidly at the expense of the surrounding nanocrystalline matrix. The addition of NiO layers in the Ni suppressed grain growth and twin formation upon annealing, with increasing oxide content resulting in decreasing extent of grain growth. In pure Ni, the post-annealing texture was found to be composed of a strong {001} texture coupled with the four {122} twin variants from the {001}. With the addition of NiO, annealing twinning, and hence the {122} orientation, was suppressed and instead the final texture was composed of the {001} and {111} orientations.

Influence of corrosion of SS316L bipolar plate on PEFC performance

This paper presents an investigation concerning the effect of metallic bipolar plate corrosion on reducing the power generation performance of a polymer electrolyte fuel cell (PEFC). The power generation performance of a single cell having a stainless steel (SS316L) bipolar plate only on the anode side was evaluated experimentally. The results made clear the corrosion behavior on the bipolar plate and the cause of the decline in power generation performance of the cell. The principal cause of the performance decline was an increase in contact resistance between the bipolar plate and the gas diffusion layer (GDL). That is attributed to an increase of iron oxide content in a passive film over the entire bipolar plate surface and precipitation of thick iron oxides in the gas downstream area. The leaching of Fe ions outside the cell was negligible, as was their permeation from the anode to the cathode. Accordingly, there were virtually no signs of an accelerated decline in the conductivity of the electrolyte or its decomposition.

Potential effects of yohimbine and sildenafil on erectile dysfunction in rats

In this study the effects of yohimbine and sildenafil on cold stress-induced erectile dysfunction in rats were investigated. Yohimbine hydrochloride (0.2mg/kg, i.p.) and sildenafil citrate (20mg/kg, i.p) were administered to rats 1h before the stress session daily for 14 consecutive days and their effect was assessed. Results of this section revealed that, immersion of rats in cold water significantly decreased sexual arousal and motivation as indicated by increased latencies and intervals. Furthermore decreased copulatory performance and potency as indicated by decreased ejaculation frequency was observed. Decreased copulatory activity was confirmed by decreased testosterone, luteinizing hormone (LH) and follicle-stimulating-hormone (FSH) levels as well as decreased cholesterol content in rat testes. Treatment with yohimbine or sildenafil significantly increased the sexual arousal and potency and corrected the effects induced by stress on the mating behavior of male rats. On the contrary they did not significantly alter testosterone, FSH and LH levels which is reflected by failure of both drugs to alter cholesterol content in rat testes. Regarding the effect of yohimbine and sildenafil on isolated rat corpus cavernosum, their cumulative dose response curves (3×10−7, 3×10−6 and 3×10−5M) were determined in corpus cavernosum strips isolated from normal rats and pre-contracted with phenylephrine (3×10−6M) were also assessed. Results of this part showed that both yohimbine and sildenafil have a relaxant effect on rat corpus cavernosum strips in a dose dependant manner, which is confirmed by the increase in nitric oxide content in rats' penis shown by sildenafil.

Influence of Niobium Oxide on the Mechanical Properties of Hydroxyapatite

The goal of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from both natural sheep bone and commercial synthetic hydroxyapatite with niobium oxide addition ( 5 and 10 wt%). The samples were subjected to sintering at different temperatures between 1000°C and 1300°C. Microstructures and mechanical properties of sheep hydroxyapatite (SHA) and commercial synthetic hydroxyapatite (CSHA)-niobium oxide composites were investigated. The production of hydroxyapatite (HA) from natural sources is preferred due to economical reason. The aim of development of SHA and CSHA based niobium oxide composites is to improve mechanical properties of HA. The physical and mechanical properties were determined by measuring density, compression strength and Vickers microhardness (HV). Structural characterization was carried out with X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies. In all composites, density values and mechanical properties increased with increasing sintering temperature. The increase of niobium oxide content in all composites showed better mechanical properties. Both of SHA and CSHA composites with at 1300°C sintering temperature showed nearly the same compression strength value.

Swainsonine as a lysosomal toxin affects dopaminergic neurons

Swainsonine (SW) is an indolizidine triol plant alkaloid isolated from the species Astragalus, colloquially termed locoweed. When chronically ingested by livestock and wildlife, symptoms include severe neuronal disturbance. Toxicity to the central and peripheral nervous system is caused by inhibition of lysosomal α-mannosidase (AMA) and accumulation of intracellular oligosaccharide. Consequently, SW has been used as a model substance in investigations of lysosomal storage diseases. Involvement of the basal ganglia has been postulated due to the neuronal symptoms of affected animals. Therefore, primary midbrain cultures from embryonic mice containing dopaminergic neurons were utilized in this study. Neural cells were exposed to SW (0.01-100 μM) for 72 h. AMA activity was 50 % inhibited at 1 μM SW. Cytotoxic changes in cultures were observed above 25 μM SW by increases in lactate dehydrogenase activity and nitric oxide content. Neurotoxicity to dopaminergic cells was visualized by tyrosine hydroxylase immunohistochemistry. Structural degeneration scored as dendritic shortening and shrinkage of cell bodies was dose-dependent and resulted in nerve loss above 25 μM. SW exposure caused progression from reversible to irreversible cytotoxicity. Partial regeneration of AMA-activity in culture was observed on removal of SW. The antioxidative vitamins ascorbic acid and tocopherol (both 100 μM) partially reversed the toxic effect on dopaminergic cells and ascorbic acid decreased AMA inhibition. Thus, neuronal midbrain cell cultures can demonstrate the neurotoxic action of SW and cytoprotective strategies may be tested at a single nerve cell level.

Effect of iron oxide addition on structural properties of calcium silico phosphate glass/glass-ceramics

Glasses with nominal composition 34SiO2–(45−x) CaO–16 P2O5–4.5 MgO–0.5 CaF2–x Fe2O3 (where x=5, 10, 15, 20wt.%) have been synthesized by melt quench technique. These have been investigated for structural features by using Fourier transform infra-red (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Results have shown an increase in fraction of non‐bridging oxygen in glasses with an increase in iron oxide content up to 15wt.% and subsequently decreases with further increase in iron oxide content to 20wt.%. These effects are originated by the incorporation of Fe2O3 into the silica network. Iron oxide behaves as a network modifier at low concentration and stabilizes the glass network at higher content. The glass-ceramics exhibit an increase in the formation of magnetite phase with an increase in iron oxide. The glass phase in the glass-ceramics matrix, controls the surface dissolution, which in turn decides the response of the material in-vitro. The glass-ceramics with 15wt.% iron oxide has shown optimum response in simulated body fluid.

Influence of Oxide Additions on the Porosity Development and Mechanical Properties of A356 Aluminium Alloy Castings

Three A356 aluminium alloy melts with different oxide contents were produced by mixing alloy turnings with ingot material. The melts had a constant hydrogen level and were cast in a step mould steel die. The resulting casting porosity was characterized using the Archimedes’ method and image analysis. Melt quality was accessed using a Porous Disc Filtration Apparatus (PoDFA) and the Reduced Pressure Test (RPT). It was shown that oxide additions lead to higher amounts of fine structured oxide films resulting in an increase of the fraction of small pores. Shrinkage porosity with its inherent partially elongated and interdendritic pore morphology was predominant. Ultimate tensile strength (UTS) and elongation from thin and thick sections in the step castings deteriorated with increased oxide content; UTS decreased from 3–18 % and elongation from 18–38 % with oxide additions as the section thickness increased. The melt cleanliness analyses from PoDFA were consistent with the oxide additions.

Application of neodymium oxide to increase the whiteness of porcelain

The spectral-colorimetric and luminescence characteristics of porcelain with neodymium oxide addition are studied. It is shown that whiteness increases when a small amount of neodymium oxide is present and that the coloring process begins as the neodymium oxide content increases. The increase in whiteness of porcelain is explained by a combination of two optical effects: increase of reflection in the blue-azure range of the visible spectrum due to sensitization radiation of the neodymium ion in the region 390 – 480 nm and a yellowness decrease due to the absorption of the neodymium ion in the interval 60 – 590 nm and a shift of the reflection peak into the blue-green region of the spectrum.

THERMAL STABILITY AND SURFACE STRUCTURE OF SnO2-CeO2 IMPREGNATED CATALYSTS

Newly prepared SnO2-CeO2 catalyst samples used as depollution catalysts were characterized applying low-temperature nitrogen adsorption (BET), X-ray diffraction (XRD), thermo-gravimetry (TG-dTG) and temperature-programmed reduction (TPR) methods. Pure SnO2 has higher surface area (17 m2/g) than the pure CeO2 (8 m2/g). Addition of organic tin oxide precursor to ceria in amount of 5 wt% slightly decreases the surface area of CeO2 (SSn5-Ce= 7 m2/g). The increase of tin oxide content to 10 and 20 wt% increases the surface area of the catalyst (SSn10-Ce= 9 m2/g; SSn20-Ce= 10 m2/g). A similar effect was observed for pores of 1.7-300nm size. Catalyst sample Sn5-Ce exhibited the lowest pore volume, which increases with increasing the amount of tin oxide. Tin dioxide in Sn-Ce samples with lower loadings of SnO2 (.10 wt%) were well dispersed showing amorphous structure. High loading (20 wt%) of tin dioxide in Sn-Ce showed XRD lines of formation of cassiterate crystalline structure of SnO2 without evidence of solid solution formation. In case of SnO2 the TPR profile exhibits a major peak at about 545 C with much greater intensity than in case of CeO2, revealing that SnO2 was more easily reducible than CeO2. Sn-Ce samples exhibit reducibility at lower temperatures (between 545-635 C) compared to the single tin dioxide (750 C).

MIE and flame velocity of partially oxidised aluminium dust

This work presents experimental tools for the determination of Minimum Ignition Energy (MIE) and results concerning the influence of an initial oxidation state on ignition threshold energies and flame velocity. These studies are carried out with micrometric aluminium particles which are oxidised using an anodising process. The first part of this work concerns the description of the experimental devices (Hartmann tube, for MIE measurements, and constant volume combustion chamber for flame velocity measurement with using high speed recording shadowgraphy). In the second part, a review of some results obtained for the sensitivity (MIE) of aluminium particle evolution versus particle diameter, air-fuel equivalence ratio and oxide content is presented. The effect of the oxide content is demonstrated: the MIE increases with the initial oxide content. The sensitivity of oxidised dust remains relatively high for high oxide contents (17.1wt%). The flame velocity is also modified and decreases as the oxide content increases. The most important result seems to be the role of the water content contained in the oxide shell which increases the reactivity of the oxidised aluminium dust.

Molecular Dynamics and Macroscopic Properties of Magnetic Microgels

Thermo-sensitive microgels based on poly(N-isopropyl acrylamide) (PNIPAM) were covered with nanoparticles of γ-Fe2O3 with size around 6 nm. When the inorganic cover was 18% (w/w) respect the polymer part, the microgels presented magnetic properties in addition to their inherent thermo-sensitivity. The interactions existing between the magnetic nanoparticles and the polymer matrix provoke the shifting of the microgel volume transition to higher temperatures when the amount of γ-Fe2O3 increases. The study performed using incoherent quasielastic neutron scattering (IQNS) confirms that the presence of inorganic nanoparticles affects the PNIPAM chain motions. Thus, in the swollen state both, the mean square displacement of the polymer segments and the diffusive motion of the polymer chains, decrease as the iron oxide content increases. The reduction of vibrational and diffusional motions of the polymer chains is attributed to the formation of hydrogen bonds between the amide groups of the polymer matrix and the OH groups of the magnetic nanoparticles that explains the reduction of the swelling capacity of the microgels and the shift of the polymer volume transition to higher temperatures with increasing the iron content.

The influence of calcination parameters on free calcium oxide content in natural hydroxyapatite

Effect of calcining temperature and time on the content of free CaO in hydroxyapatite of natural origin is presented. Hydroxyapatite was obtained from pork bones in the course of a three-stage process: hydrolysis with the application of lactic acid, pre-calcination at 600 °C and main calcination stage within the temperature range of 750–950 °C. Calcination was conducted in an electrically heated stationary chamber oven in air atmosphere and in a laboratory scale rotary kiln equipped with a gas burner. The FT-IR spectra confirmed that all organic substances were removed during the calcination process. An increase in free calcium oxide content in hydroxyapatite from 0.003% to 0.023% was caused by the increase of calcining temperature from 750 °C to 950 °C respectively. Calcining time at 950 °C gave a distinct impact upon free CaO content ranging from 0.014% (2 h) to 0.023% (3 h). Hydroxyapatite calcined in the rotary kiln contained the lowest amount of free calcium oxide: 0.002% (750 °C) and 0.003% (950 °C). A method of neutralizing of free calcium oxide, present in calcined hydroxyapatite powders of natural origin, through CaO transformation into hydroxyapatite by application of diluted thermic phosphoric acid has been developed.

Effect of CuO addition on the optical and electrical properties of sodium zinc borophosphate glasses

Sodium borophosphate glasses doped with copper ions having general composition 20Na 2O–20ZnO–25B 2O 3–(35- x) P 2O 5– x CuO ( x=1–8 mol %) were prepared using conventional melt-quench method and characterized by density, UV–visible optical absorption, photoluminescence and conductivity measurements. E optical values for different glass samples are found to decrease systematically from 3.5 to 2.5 eV with increase in CuO content in the glass. Network modifying action of CuO with the glass network has been confirmed from the UV–visible optical absorption studies. Presence of Copper in the form of Cu + species has been confirmed from photoluminescence measurements. The electrical conductivity ( σ) increases with increase in copper oxide content in the glass and temperature dependence of electrical conductivity confirmed the semiconducting nature of the samples.

Protective effect of lisinopril on hepatic ischemia/reperfusion injury in rats

Objective:Ischemia/reperfusion (I/R) injury plays a key role in the pathogenesis of hepatic failure in several clinical settings such as liver resection or transplantation. Lisinopril, a widely prescribed drug for various cardiovascular conditions, has been reported to have diverse pharmacological properties. The aim of this study, therefore, was to evaluate a potential protective effect of lisinopril on hepatic I/R injury in rats.Materials and Methods:In anesthetized rats, partial hepatic ischemia was applied for one hour followed by two hours reperfusion. Biochemical analysis of serum and hepatic tissue was done. Hepatic tissue was also subjected to electron microscopy.Results:Pre-ischemic treatment with lisinopril (10 mg/kg) exerted protection against I/R-induced hepatocellular injury as evident by significant decrease in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin levels, along with hepatic lipid peroxidation, expressed as malondialdehyde content, with a concurrent increase in hepatic nitric oxide content as compared to I/R group. The electron microscopic examination indicated that lisinopril can effectively protect against hepatic I/R injury.Conclusion:Lisinopril provides a protection against hepatic I/R injury in rats. The protective effect is associated with reduction of oxidative stress-induced lipid peroxidation level and enhancement of nitric oxide availability.

Preparation, characterization and antimicrobial property of micro-nano sized Na-borosilicate glass powder with spherical shape

Spherical glass powders are potential materials for the production of a high performance coating where uniform porosities are obtainable with a high hydrophilic nature. Coating with antimicrobial properties increases the engineering properties of the materials. In this study, Ag 2O doped (0.5–5 wt.% Ag 2O) Na-borosilicate micro (1.227 μm) and nano (134 nm) sized glass powders were prepared by ultrasonic spray pyrolysis. The antimicrobial properties against gram positive bacteria ( Bacillus cereus and Staphylococcus aureus), gram negative bacteria ( Escherichia coli) and yeast ( Candida albicans) were determined using the agar-disc diffusion and modified agar well methods. The results show that the prepared powders are spherical, of amorphous structure and have a very smooth surface. The increase in silver oxide content increased the powders' antimicrobial activity. Powders with 2.5 wt.% Ag 2O content are highly active (?) against the three types of microorganisms. The nano sized powder also increased antimicrobial activity.

Towards understanding of the germanate anomaly in europium–lead–germanate glasses

Glasses in the system xEu 2O 3·(100 − x)[7GeO 2·3PbO 2] with 0 ≤ x ≤ 25 mol% have been prepared from melt quenching method. Influence of europium ions on structural behavior in lead-germanate glasses has been investigated using infrared spectroscopy and DFT calculations. The structural changes have been analyzed with increasing rare earth concentration. The general trend in the intensity of IR spectra is to increase with Eu 2O 3 content in the 700–1200 cm − 1 region, whereas the intensity in the 400–600 cm − 1 is remained almost unaffected. This suggests that the glass network modification has taken place mainly in the germanate part whereas the lead part remained unmodified and its network consists mainly from the [PbO 3] and [PbO 4] structural units. Thus, the germanate network in europium–lead–germanate glasses exists mostly as the [GeO 4] tetrahedral units, the [GeO 6] octahedral structural units and with interconnected through Ge–O–Ge bridges in [GeO 4] structural units. These europium–lead–germanate systems exhibit a photosensitive effect which can be induced through laser exposures ( λ = 633 nm) directly on the bulk sample. Structural investigations by FTIR spectroscopy show that the presence of fivefold Ge as a possible transitional phase from four to sixfold Ge was necessary. At higher content of europium oxide, the anomaly behavior of the germanium is due to the formation of small membered rings of [GeO 4] and the apparition of non-bridging oxygens. The reversion to the formation of non-bridging oxygens may thus tend to become energetically more favorable as europium oxide content increases.

Nano ZnO-activated carbon composite electrodes for supercapacitors

A symmetrical (p/p) supercapacitor has been fabricated by making use of nanostructured zinc oxide (ZnO)–activated carbon (AC) composite electrodes for the first time. The composites have been characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD). Electrochemical properties of the prepared nanocomposite electrodes and the supercapacitor have been studied using cyclic voltammetry (CV) and AC impedance spectroscopy in 0.1 M Na2SO4 as electrolyte. The ZnO–AC nanocomposite electrode showed a specific capacitance of 160 F/g for 1:1 composition. The specific capacitance of the electrodes decreased with increase in zinc oxide content. Galvanostatic charge-discharge measurements have been done at various current densities, namely 2, 4, 6 and 7 mA/cm2. It has been found that the cells have excellent electrochemical reversibility and capacitive characteristics in 0.1 M Na2SO4 electrolyte. It has also been observed that the specific capacitance is constant up to 500 cycles at all current densities.

Investigation of the Relationship between Hydrogen Bonds and Macroscopic Properties in Hybrid Core−Shell γ-Fe2O3−P(NIPAM-AAS) Microgels

We investigate in a hybrid material the interactions existing between magnetic nanoparticles of gamma-Fe(2)O(3) and the polymer matrix constituted by core-shell poly(N-isopropylacrylamide-sodium acrylate) microgels. These interactions provoke the shifting of the microgel volume phase transition to higher temperatures when the amount of gamma-Fe(2)O(3) increases. The study was performed using different techniques such as incoherent quasi-elastic neutron scattering (IQNS), infrared spectroscopy (FTIR-ATR), and dynamic light scattering (DLS). Below the low critical solution temperature (LCST) of the polymer, the IQNS data confirm that the presence of inorganic nanoparticles affects the PNIPAM chain motions. Thus, in the swollen state both the mean-square displacement of the polymer segments and the diffusive motion of the polymer chains decrease as the iron oxide content increases. The FTIR-ATR study indicates that the reduction of vibrational and diffusional motions of the polymer chains is due to the formation of hydrogen bonds between the amide groups of the polymer matrix and the OH groups of the magnetic nanoparticles. The creation of this hybrid complex would explain the reduction of the swelling capacity with increasing the iron content in the microgels. Furthermore, this interaction could also explain the shift of the polymer LCST to higher temperatures as due to the extra energy required by the system to break the hydrogen bonds prior to the PNIPAM collapse.