Contrast-enhanced ultrasound of abdominal organs in cats

The primary aim of this thesis was the evaluation of the perfusion of normal organs in cats using contrast-enhanced ultrasound (CEUS), to serve as a reference for later clinical studies. Little is known of the use of CEUS in cats, especially regarding its safety and the effects of anesthesia on the procedure, thus, secondary aims here were to validate the quantitative analyzing method, to investigate the biological effects of CEUS on feline kidneys, and to assess the effect of anesthesia on splenic perfusion in cats undergoing CEUS. -- The studies were conducted on healthy, young, purpose-bred cats. CEUS of the liver, left kidney, spleen, pancreas, small intestine, and mesenteric lymph nodes was performed to characterize the normal perfusion of these organs on ten anesthetized, male cats. To validate the quantification method, the effects of placement and size of the region of interest (ROI) on perfusion parameters were investigated using CEUS: Three separate sets of ROIs were placed in the kidney cortex, varying in location, size, or depth. The biological effects of CEUS on feline kidneys were estimated by measuring urinary enzymatic activities, analyzing urinary specific gravity, pH, protein, creatinine, albumin, and sediment, and measuring plasma urea and creatinine concentrations before and after CEUS. Finally, the impact of anesthesia on contrast enhancement of the spleen was investigated by imaging cats with CEUS first awake and later under anesthesia on separate days. -- Typical perfusion patterns were found for each of the studied organs. The liver had a gradual and more heterogeneous perfusion pattern due to its dual blood flow and close proximity to the diaphragm. An obvious and statistically significant difference emerged in the perfusion between the kidney cortex and medulla. Enhancement in the spleen was very heterogeneous at the beginning of imaging, indicating focal dissimilarities in perfusion. No significant differences emerged in the perfusion parameters between the pancreas, small intestine, and mesenteric lymph nodes. -- The ROI placement and size were found to have an influence on the quantitative measurements of CEUS. Increasing the depth or the size of the ROI decreased the peak intensity value significantly, suggesting that where and how the ROI is placed does matter in quantitative analyses. --- A significant increase occurred in the urinary N-acetyl-β-D-glucosaminidase (NAG) to creatinine ratio after CEUS. No changes were noted in the serum biochemistry profile after CEUS, with the exception of a small decrease in blood urea concentration. The magnitude of the rise in the NAG/creatinine ratio was, however, less than the circadian variation reported earlier in healthy cats. Thus, the changes observed in the laboratory values after CEUS of the left kidney did not indicate any detrimental effects in kidneys. Heterogeneity of the spleen was observed to be less and time of first contrast appearance earlier in nonanesthetized cats than in anesthetized ones, suggesting that anesthesia increases heterogeneity of the feline spleen in CEUS. ---- In conclusion, the results suggest that CEUS can be used also in feline veterinary patients as an additional diagnostics aid. The perfusion patterns found in the imaged organs were typical and similar to those seen earlier in other species, with the exception of the heterogeneous perfusion pattern in the cat spleen. Differences in the perfusion between organs corresponded with physiology. Based on the results, estimation of focal perfusion defects of the spleen in cats should be performed with caution and after the disappearance of the initial heterogeneity, especially in anesthetized or sedated cats. Finally, these results indicate that CEUS can be used safely to analyze kidney perfusion also in cats. Future clinical studies are needed to evaluate the full potential of CEUS in feline medicine as a tool for diagnosing lesions in various organ systems.

Pressure sensor based tsunami detection system: A laboratory study

In this paper, we present the study and implementation of a low-cost system to detect the occurrences of tsunamis at significantly smaller laboratory scale. The implementation is easily scalable for real-time deployment. Information reported in this paper includes the experimentally recorded response from the pressure sensor giving an indication as well as an alarm at remote place for the detection of water turbulence similar to the case of tsunami. It has been found that the system developed works very well in the laboratory scale.

Photocatalytic Activity of Microwave Plasma-Synthesized TiO2 Nanopowder

Nanocrystalline TiO2 was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV-vis spectroscopy and BET surface area analyzer. The synthesized TiO2 powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO2 catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO2 as compared to that over commercial Degussa P-25 TiO2.

Components of fractionated stallion seminal plasma and the effects of seminal plasma on sperm longevity

Seminal plasma (SP) is the fluid portion of semen, secreted by the epididymides and the accessory glands before and during ejaculation. The stallion s ejaculate is a series of jets that differ in sperm concentration, semen volume and biochemical composition. Before the actual ejaculation, a clear and watery pre-sperm fluid is secreted. The first three jets form the sperm-rich fractions, and contain ¾ of the total number of sperm. The semen volume and sperm concentration in each of the jets decrease towards the end of the ejaculation, and the last jets are sperm-poor fractions with a low sperm concentration. The aims of these studies were to examine the effects of the different SP fractions, and the presence of SP, on sperm survival during storage. Pre-sperm fluid, and semen fractions with a high (sperm-rich) and low (sperm-poor) sperm concentration were collected in five experiments. The levels of selected enzymes, electrolytes and proteins in different SP fractions were determined. These studies also aimed at assessing the individual variation in the levels of the selected SP components and in the effects of SP on spermatozoa. The association between the components of SP and semen quality, sperm longevity, and fertility was examined with a stepwise linear regression analysis. Compared to samples containing SP during storage, centrifugation and the subsequent removal of SP reduced sperm motility parameters during 24 h of cooled storage in all SP fractions, but sperm membrane integrity was not affected. Some of the measured post-thaw motility parameters were also higher in samples containing SP compared to samples stored without SP. In contrast, the proportion of DNA-damaged spermatozoa was greater in the samples stored with SP than those without SP, and this effect was seen in both sperm-rich and sperm-poor fractions. There were no differences in DNA integrity between fractions stored with SP, but the sperm-rich fraction showed less DNA damage than the sperm-poor fraction after SP removal. The differences between fractions in sperm motility after cooled storage were non-significant. The levels of alkaline phosphatase, acid phosphatase and β-glucuronidase were higher in the sperm-rich fractions compared to the sperm-poor fractions, while the concentrations of calcium and magnesium were higher in sperm-poor fractions than in sperm-rich fractions. The concentrations of sodium and chloride were highest in pre-sperm fluid. In the sperm-poor fraction, the level of potassium was associated with the maintenance of sperm motility during storage. The levels of alkaline and acid phosphatase were associated with sperm concentration and the total number of spermatozoa in the ejaculates. None of the measured SP components were correlated to the first cycle pregnancy rate. In summary, the removal of SP improved DNA integrity after cooled storage compared with samples containing SP. There were no differences in the maintenance of sperm motility between the sperm-rich and sperm-poor fractions and whole ejaculates during cooled storage, irrespective of the presence of SP. The lowest rate of DNA damage was found in the sperm-rich fractions stored without SP. In practice, the results presented in this thesis support the use of individual modifications of semen processing techniques for cooled transported semen from subfertile stallions.

Vitamin A and thyroxine carrier proteins in chicken plasma Steady-state control of the plasma level of free retinol-binding protein and free thyroxine

1. 1. The binding parameters of prealbumin-2 with retinol-binding protein and thyroxine (T4) revealed the existence of distinct and multiple sites for both retinol-binding protein and T4. 2. 2. From the analysis of binding parameters of retinol-binding protein with prealbumin-2 it is clear that under steady-state conditions about 99% of the holo-retinol-binding protein remains bound to prealbumin-2. 3. 3. Equilibrium dialysis studies on binding properties of thyroid hormones with prealbumin-2 revealed that it has a single high affinity site and three low affinity sites. 4. 4. The occurrence of three carrier proteins for thyroid hormones, thyroxine-binding globulin, prealbumin-2 and albumin has been demonstrated. However, the chicken thyroxine-binding globulin differs from human thyroxine-binding globulin by being relatively less acidic and occuring at a two-fold lower concentration. But the thyroid hormone binding parameters are comparable. 5. 5. Highly sensitive methods were developed for determination of T4 binding capacities of the various proteins and plasma level of total T4 by fractionation of carrier proteins and further quantitatively employing in electrophoresis and equilibrium dialysis. 6. 6. The thyroxine-binding proteins were found to be two types, one (viz., thyroxine-binding globulin) of great affinity but of low binding capacity, which mainly acts as reservoir of T4, and another (viz.,prealbumin-2) of low affinity but of high binding capacity, which can participate predominantly in the control of the free T4 pool.

An assessment of the reduction potential of hydrogen plasma

Hydrogen plasma can be used for deoxidation of functional materials containing reactive metals in both bulk and thin film forms. Since the different species in the plasma are not in thermodynamic equilibrium, application of classical thermodynamics to the analysis of such a system is associated with some difficulties. While global equilibrium approaches have been tried, with and without additional approximations or constraints, there is some ambiguity in the results obtained. Presented in this article is the application of a local equilibrium concept to assess the thermodynamic limit of the reaction of each species present in the gas with oxides or oxygen dissolved in metals. Each reaction results in a different pal tial pressure of H2O. Because of the higher reactivity of the dissociated and ionized species and the larger thermodynamic driving force for reactions involving these species, they act as powerful reducing agents. It is necessary to remove the products of reaction from the plasma to prevent back reaction and gradual approach to global equilibrium. A quantitative description using the framework of the Ellingham-Richardson-Jeffes diagrams is presented.

Chicken prealbumin: Nature of its heterogeneity and binding of plasma retinol-binding protein and thyroid hormones

The heterogeneity of chicken prealbumin (PA) has been shown to be due to the occurrence of three different plasma proteins (PA1 PA2 and PA3). Equilibrium dialysis studies revealed that the thyroid hormones bind specifically to PA2. These hormones bind at the same site on PA2. Circular dichroism studies failed to reveal conformational changes on interaction of retinol-binding protein and thyroid hormone with PA2. Both retinol-binding protein and thyroid hormone are independently transported by PA2.

Droplet Epitaxy of InN Quantum Dots on Si(111) by RF Plasma-Assisted Molecular Beam Epitaxy

InN quantum dots (QDs) were fabricated on Si(111) substrate by droplet epitaxy using an RF plasma-assisted MBE system. Variation of the growth parameters, such as growth temperature and deposition time, allowed us to control the characteristic size and density of the QDs. As the growth temperature was increased from 100 C to 300 degrees C, an enlargement of QD size and a drop in dot density were observed, which was led by the limitation of surface diffusion of adatoms with the limited thermal energy. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to assess the QDs size and density. The chemical bonding configurations of InN QDs were examined by X-ray photo-electron spectroscopy (XPS). Fourier transform infrared (FTIR) spectrum of the deposited InN QDs shows the presence of In-N bond. Temperature-dependent photoluminescence (PL) measurements showed that the emission peak energies of the InN QDs are sensitive to temperature and show a strong peak emission at 0.79 eV.

Optimization of ion energy spread in inductively coupled plasma source designed for focused ion beam applications

The ion energy distribution of inductively coupled plasma ion source for focused ion beam application is measured using a four grid retarding field energy analyzer. Without using any Faraday shield, ion energy spread is found to be 50 eV or more. Moreover, the ion energy distribution is found to have double peaks showing that the power coupling to the plasma is not purely inductive, but a strong parasitic capacitive coupling is also present. By optimizing the various source parameters and Faraday shield, ion energy distribution having a single peak, well separated from zero energy and with ion energy spread of 4 eV is achieved. A novel plasma chamber, with proper Faraday shield is designed to ignite the plasma at low RF powers which otherwise would require 300-400 W of RF power. Optimization of various parameters of the ion source to achieve ions with very low energy spread and the experimental results are presented in this article. (C) 2010 Elsevier Ltd. All rights reserved.

Self-assembled flower-like nanostructures of InN and GaN grown by plasma-assisted molecular beam epitaxy

Nanosized hexagonal InN flower-like structures were fabricated by droplet epitaxy on GaN/Si(111) and GaN flower-like nanostructure fabricated directly on Si(111) substrate using radio frequency plasma-assisted molecular beam epitaxy. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the crystallinity and morphology of the nanostructures. Moreover, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to investigate the chemical compositions and optical properties of nano-flowers, respectively. Activation energy of free exciton transitions in GaN nano-flowers was derived to be similar to 28.5 meV from the temperature dependent PL studies. The formation process of nano-flowers is investigated and a qualitative mechanism is proposed.

The Single Langmuir Probe under Orbital-Limited Conditions in a Low-Density Collisional Plasma

The cylindrical Langmuir probe under orbital-limited conditions was used to determine the charge density in a low-density collisional plasma. The Langmuir's theory was applied to both electron and ion saturation currents in their respective accelerating regions. Present study indicates that the length of the probe significantly affects the probe characteristics. A probe of suitable length under orbital-limited conditions may be useful under the experimental conditions where the radius of the probe is much smaller than the Debye lengt.