Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains viii, 65 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 60-64).

The permeable press experiment was performed for aqueous clay mineral systems to understand the relationship between the water film thickness and the applied permeable pressure. Water film thickness between particles was calculated from the particle size and the linear drying shrinkage of pressed bodies. The permeable press experimental results were compared to the calculated total interaction pressures between particles using the DLVO theory. The kaolinite and the metakaolinite had the same particle shape. Kaolinite particles were crystalline, and metakaolinite particles were short-range order. The kaolinite had the point of zero net charge, PZNC, at pH 5.7. However, the kaolinite showed multi-cross points at pHs 4.6, 5.7, 6.2, and 7.2. These multi-cross points were in agreement with the theoretical titration using the two-site surface complex reaction model by Carroll-Webb and Walther. On other hand, the metakaolinite had the PZNC at pH 7.2 as a common intersection point. If the zeta potential at pH(PZNC) is identical to the silica basal surface potential, the silica surface charge densities are calculated as - 2.6 μC cm⁻² for the kaolinite and - 2.7 μC cm⁻² for the metakaolinite, respectively. The calculated surface charge density is equivalent to one aluminum atom substituted in 54 silicon atoms in the silica tetrahedral layer. The total interaction pressures using the DLVO theory corresponded to the permeable press experimental results of the metakaolinite-0.1 M NaCI systems. The surface of the metakaolinite was estimated to have immobile water layers between 5 and 8 molecules thick. The metakaolinite samples cracked in experiments when the applied permeable pressure increased. This phenomenon can be explained by a vanishing capillary pressure: contacting immobile layers. The permeable press experimental results of all the kaolinite systems were significantly higher than the calculated total interaction pressures. The slope of the natural log of the permeable pressure and the water film thickness of the kaolinite systems indicated the existence of a longer-range repulsive pressure than that of the metakaolnite systems. The DLVO theory cannot explain the kaolinite systems because the nature of materials, such as an atomic configuration of the surface, which induces the structural forces, is not considered.

This study involves a detailed analysis of the dynamics of the oil sector in Libya, and reviews the process of economic development in order to identify key issues and priorities for future development. As with many other developing countries, Libya has received insignificant FDI inflows over the study period 1962-2003. The experience of the developing world in particular suggests that it is far from certain whether FDI will indeed act as an engine of transition in Libya. Libya places great importance on foreign capital in the oil sector as a critical element of economic growth. The main aim of this study is to identify and analyze the economic factors giving rise to FDI inflows to the Libyan oil sector during the study period. It reviews FDI trends in Libya, both in the regional and international contexts, and takes into account the evolution of various policies and measures introduced in order to attract FDI. Primary data were collected through a questionnaire-based survey from a sample of 35 foreign oil companies in Libya, along with 20 interviews with government officials. Using annual time series data, the study finds that the nationalization of foreign oil companies in 1972 has negatively influenced FDI inflows; whereas country wealth and the lagged value of FDI positively influence FDI inflows to the Libyan oil sector. Since sanctions were lifted, Libya's relations with the world are becoming normalized and there are opportunities for foreign investment in every sector of the economy associated with the government's new open policy of adopting FDI, which is already visibly growing. Libya is considering changing its 40-years old hydrocarbon legislation to improve the terms for foreign investment. Therefore, the Libyan foreign investment environment is promising for the foreseeable future.

Zinc (Zn) is an essential trace element and its deficiency is known to compromise a wide range of functions, including vascular function and immune function. The hypothesis of the thesis was that suboptimal Zn status would induce changes in the vascular system, thus raising the potential risk of developing atherosclerosis. After 2 wk, aorta was taken from male adult rats fed by either acute Zn deficient (AZD, <1mg Zn/kg), Zn adequate Pair fed of AZD (PF, 35mg Zn/kg), or Zn adequate control (ZA, 35mg Zn/kg, fed ad libitum) diet. It was found most genes which were significantly regulated between AZD and PF aorta belong to cytoskeleton remodelling. Plasma from the same rats was used to incubate primary VSMC in vitro. Dramatic changes of gene expression in pathways associated with immune function. While AZD plasma induced marked changes in VSMC gene expression in vitro, no significant change was found by depleting Zn from PF plasma. Therefore it is possible that a Zn deficiency induced humoral factor was responsible for influencing VSMC gene expression. By semi-purifying plasma using gel filtration and molecular filtration, it was confirmed that the humoral factor has a molecular weight of around 2kDa and is thought to be a peptide hormone, which could serve as a potential biomarker of Zn status. Splenocytes and whole blood were taken from rats and used to measure cytokine secretion before and after either LPS or ConA treatment. Different concentrations of several cytokines, such as IL2, IL6, TNFα and IFNγ were found from different Zn status. Overall the thesis emphasises the participation of Zn in several aspects of the vascular system, such as regulating cytokine production and maintaining vascular structure. It provides important evidence of the role that Zn plays in the development of atherosclerosis.

Chromium has been reported to increase glucose clearance in insulin resistant and diabetic populations. Skeletal muscle is the tissue primarily responsible for glucose clearance. We therefore tested the effect of chromium chloride (CrCl3) on skeletal muscle glucose uptake both in the absence and presence of a submaximal level of insulin via the rat hindlimb perfusion technique. 0.096 μM CrCl3 was used with and without 200 μU/ml insulin. Our testing showed that insulin significantly increased [H3]-2 deoxyglucose (2-DG) uptake in both the gastrocnemius and quadriceps muscles. Additionally, the combination of CrCl3 and insulin (Cr-sIns) led to greater amounts of 2-DG uptake than insulin alone (sIns) in both the gastrocnemius (Cr-sIns 6.49±0.75 μmol/g/h, sIns 4.83±0.42 μmol/g/h) and quadriceps (Cr-sIns 6.74±0.62 μmol/g/h, sIns 4.54±0.43 μmol/g/h). However, CrCl3 without insulin (Cr) had no affect on 2-DG uptake above basal (Bas) in both the gastrocnemius (Cr 1.45±0.14 μmol/g/h, Bas 1.61±30 μmol/g/h) and the quadriceps (Cr 1.35±0.15 μmol/g/h, Bas 1.27±0.13 μmol/g/h). It has been speculated that chromium works to increase glucose uptake by increasing insulin signaling. To examine this, we used western blotting analysis to test both Akt and AS160 phosphorylation in the mixed gastrocnemius. We found that insulin increased Akt and AS160 phosphorylation, but chromium had no affect on Akt (Cr-sIns 25%±2%, sIns 22%±4%) or AS160 (Cr-sIns 35%±5%, sIns 36%±4%) phosphorylation in the absence or presence of insulin. Our results suggest that supplementation with CrCl3 can lead to an increase in glucose uptake in skeletal muscle, but only in the presence of insulin. However, this effect of CrCl3 does not appear to be a result of enhanced insulin signaling. / text

No description available.

No description available.

No description available.

No description available.

Per pastaruosius 20 metų daug pasiekta auginant viščiukus broilerius – ženkliai padidėjo viščiukų augimo greitis ir maisto pasisavinimo efektyvumas. Šiuolaikiniai komerciniai hibridai greitai vystosi ir jiems reikia daug energijos turinčių lesalų, kurie leidžia maksimaliai išnaudoti jų genetines galimybes. Daugiau pasiekta ir vištų dedeklių lesinime balansuojant lesalus skirtingais dėslumo etapais, ypač ankstyvojo dėjimo periodu. Pastaruoju metu paukščių lesinime didelis dėmesys skiriamas optimaliam kalcio, fosforo, natrio, kalio ir chloro subalansavimui. Parinkus netinkamas kalcį ir fosforą nešančias medžiagas, taip pat nesubalansavus natrio, kalio ir chloro tarpusavio santykio, t.y. anijonų katijonų balanso, padidėja vandens suvartojimas, sutrinka virškinimo trakto mikrobiologinė pusiausvyra, blogėja kraiko kokybė ir mikroklimato parametrai, susidaro sąlygos paukščiams susirgti ascitais, padaugėja paukščių staigių gaišimo atvejų. Vitaminai ir mineralai yra svarbi sudedamoji paukščių raciono dalis. Šios medžiagos įtraukiamos į racioną kaip priedai atitinkamais kiekiais, kad būtų patenkintas jų poreikis sveikiems produkciją duodantiems paukščiams. Mineralų ir vitaminų trūkumas gali būti kritiškas tam tikrais organizmo vystymosi etapais, todėl kai kurie autoriai teigia, kad net ir trumpas vitaminų bei mineralų apribojimas augimo fazės metu gali turėti neigiamų pasekmių. Magistrinio darbo tikslas – nustatyti mineralinių medžiagų įtaką dėsliųjų vištų ir viščiukų broilerių... [toliau žr. visą tekstą] / Minerals play a very important role in digestion and metabolism of poultry. They are necessary, for the maintenance, growth, production and health of birds. Laying hens also require minerals, primarily calcium, for eggshell formation. Minerals is divided into the macrominerals (those needed in relatively large amounts) and the micro- or trace minerals. Although microminerals are required only in small amounts, the lack of an adequate dietary supply can be just as detrimental to poultry as a lack of one of the macrominerals. Grains are low in minerals, so all poultry feeds contain supplemental sources. Calcium, phosphorus and salt are needed in the greatest amounts. Microminerals such as iron, copper, zinc, manganese and iodine are normally supplied through a trace mineral mix. The minerals influence by the bird‘s physiological status, requirement of minerals and its source is describe in the theory part. Two experiment were performed with broiler chickens and laying hens. The feed intake, feed conversion ratio, birds mortality, the degree of mineralization in the bone tibia, pH, macroelements Ca, P, Mg, Na, K, Cl and alkaline phosphatase in the blood serm were researched in experiment of broiler chickens. Number and weight of eggs, body weight, laying intensity, leftover and utilization of feed to get 1 kg eggs mass, quality parameters of eggshells, the physiological conditions and mortality reasons were researched in test of laying hens. Conclusions. Sodium bicarbonate was... [to full text]