Heat Transfer Analysis for Gas-to-Liquids Transportation Through Trans Alaska Pipeline

Gas-to-liquids (GTL) technology involves the conversion of natural gas to liquid hydrocarbons. In this article, theoretical studies have been presented to determine the feasibility of transporting GTL products through the Trans-Alaska Pipeline System (TAPS). To successfully transport GTL through TAPS, heat loss along the route must be carefully determined. This study presents heat transfer and fluid dynamic calculations to evaluate this feasibility. Because of heat loss, the fluid temperature decreases in the direction of flow and this affects the fluid properties, which in turn influence convection coefficient and pumping power requirements. The temperature and heat loss distribution along the pipeline at different locations have been calculated. Fairly good agreement with measured oil temperatures is observed. The powers required to pump crude oil and GTL individually, against various losses have been calculated. Two GTL transportation modes have been considered; one as a pure stream of GTL and the second as a commingled mixture with crude oil. These results show that the pumping power and heat loss for GTL are less than that of the crude oil for the same volumetric flow rate. Therefore, GTL can be transported through TAPS using existing equipment at pump stations.     

THE NIGER DELTA COMPLEX BASIN: STRATIGRAPHY, STRUCTURE AND HYDROCARBON POTENTIAL

The Agbada Formation is the major oil-producing formation in the Niger Delta Complex Basin, and overlies the Eocene Akata Formation, which is the principal hydrocarbon source rock. The Basin is deformed by large synsedimentaty faults, roll-over anticlines and diapirs; hydrocarbon accumulations are largely controlled by growth faults. A review of the influence of the stratigraphic and structural features on the migration and accumulation of hydrocarbons is given in this paper.     

TNFα-Induced LDL Cholesterol Accumulation Involve Elevated LDLR Cell Surface Levels and SR-B1 Downregulation in Human Arterial Endothelial Cells

Excess lipid droplets are frequently observed in arterial endothelial cells at sites of advanced atherosclerotic plaques. Here, the role of tumor necrosis factor alpha (TNFα) in modulating the low-density lipoprotein (LDL) content in confluent primary human aortic endothelial cells (pHAECs) was investigated. TNFα promoted an up to 2 folds increase in cellular cholesterol, which was resistant to ACAT inhibition. The cholesterol increase was associated with increased ¹²⁵I-LDL surface binding. Using the non-hydrolysable label, Dil, TNFα could induce a massive increase in Dil-LDL by over 200 folds. The elevated intracellular Dil-LDL was blocked with excess unlabeled LDL and PCSK9, but not oxidized LDL (oxLDL), or apolipoprotein (apoE) depletion. Moreover, the TNFα-induced increase of LDL-derived lipids was elevated through lysosome inhibition. Using specific LDLR antibody, the Dil-LDL accumulation was reduced by over 99%. The effects of TNFα included an LDLR cell surface increase of 138%, and very large increases in ICAM-1 total and surface proteins, respectively. In contrast, that of scavenger receptor B1 (SR-B1) was reduced. Additionally, LDLR antibody bound rapidly in TNFα-treated cells by about 30 folds, inducing a migrating shift in the LDLR protein. The effect of TNFα on Dil-LDL accumulation was inhibited by the antioxidant tetramethythiourea (TMTU) dose-dependently, but not by inhibitors against NF-κB, stress kinases, ASK1, JNK, p38, or apoptosis caspases. Grown on Transwell inserts, TNFα did not enhance apical to basolateral LDL cholesterol or Dil release. It is concluded that TNFα promotes LDLR functions through combined increase at the cell surface and SR-B1 downregulation.     

Plasticizing effect of biodegradable dipropylene glycol bibenzoate and epoxidized linseed oil on diglycidyl ether of bisphenol A based epoxy resin

Major limitation for use of epoxy thermosets in engineering applications is its sudden brittle failure. In the present study dipropylene glycol dibenzoate (DPGDB) based plasticizer is used to modify diglycidyl ether of bisphenol A (DEGEBA) based epoxy resin system via simple blending technique. Bio-based epoxidized linseed oil was also used to modify epoxy resin system and compared with DPGDB modified resin. For DPGDB modified resin storage modulus and loss modulus of the epoxy system modified with 10% plasticizer increased by 7.54% and 12.24%, respectively. The primary mechanism responsible for such behavior is improved crosslinking density. With 5% plasticizer loading, flexural strength increased by 21%. There was an improvement of 312.74% in strain at failure for 10% plasticizer loading, while preserving its mechanical strength. It was found that DPGDB based modification was better than epoxidized linseed oil modification.     

A simplified couette flow solution of non-newtonian power-law fluids in eccentric annuli

Flow of non-Newtonian fluids in both the concentric and eccentric annuli is of great importance in extruders for molten plastics and wellbore fluid circulation for the removal of drilling cuttings. The steady laminar couette flow of non-Newtonian power-law fluids in eccentric annulus is employed in this study to analyze the problems of surge or swab pressures encountered when running or pulling tubular goods (pipes) in a liquid filled borehole. This is similar to the annular space created by two long co-axial cylinders with the inner cylinder in motion at a steady velocity, and a stationary outer cylinder. The solutions of the equations of motion are presented in both dimensionless form and as a family of curves for different pipe/borehole eccentricity ratios and power-law fluid index values for a more general application. The expected error in surge computation for concentric annulus as a result of eccentricity is evaluated.     

Tabletting Properties of Musol; A New Direct Compression Vehicle

A new autocompressible vehicle, Musol, obtained by chemical modification of an edible seed polysaccharide was evaluated for direct compression properties, A Hausner ratio of 1,2 and percent compressibility of 16.7 obtained for Musol indicate that it has very good flow properties. Musol showed superiority over Avicel PH 101, USP Fast-Flo lactose, and Encompress when evaluated in terns of flow rake of powders and moisture sorption by both powders and their slugs, Compacts prepared with Musol were found to disintegrate by erosion and therefore did not perform as well as either alginic acid or Ac-disol in 250 mg Sulphadimidine tablets. However, good drug release was obtained from aspirin tablets containing 5% w/w Musol as a dry binder. The t₅₀, t₉₀ and Dissolution efficiency were as good as the values obtained with 5% w/w Avicel PH 101, A 50/50 blend of Musol and Avicel PH 101 surpassed other blends in performance.     

Life cycle assessment of MSF,MED and RO desalination technologies

In this work, a comparison of the commonly deployed commercial desalination technologies worldwide—multistage flash (MSF), multieffect evaporation and reverse osmosis (RO)—is assessed by applying life cycle analysis (LCA). LCA, a powerful, and internationally accepted tool used to examine environmental cradle-to-grave consequences of making and using products and services, identifies and quantifies energy and material usage and waste discharges. The International Standard Organization (ISO) 14000 impact factors, which are internationally accepted standard indicators for environmental impact assessment, have been evaluated, and different evaluation methods (Centre for Environmental Studies (CML) 2 baseline 2000, Eco-Points 97 and Eco-Indicator 99) have been applied to different scenarios. The assessment includes the entire life cycle of each desalination process, encompassing extraction and processing raw materials, manufacturing, transportation and distribution, plant operation and final reject disposal.     

Nephrotic syndrome in Nigerian children with homozygous sickle cell disease

Two hundred and seventy two children with the nephrotic syndrome were seen and followed up at the Paediatric Renal Unit of the University of Nigeria Teaching Hospital, Enugu over 12 1/2 year period, between June 1983 and December 1995. Of these, there were nine (3.3%) children with homozygous sickle cell disease (SS). This latter group had a mean age of 9.6 +/- 3.2 years, male to female ratio of 1:2 and serum cholesterol of 3.13 +/- 1.48 mmol/l at the time of diagnosis. The mortality rate was 55.6% in these sicklers, death occurring within one and a half to five years of diagnosis. Causes of death were attributable to sickle cell disease in 60%, renal diseases in 20%, and other causes in 20%. Renal biopsy in two of the sicklers showed membrano-proliferative glomerulonephritis (MPGN) and focal glomerulosclerosis (FGS) respectively. Homozygous sickle cell disease does seem to predispose to the development of the nephrotic syndrome and those that do develop nephrotic syndrome exhibit some special characteristics, when compared to non-sicklers with nephrotic syndrome. These include older age of onset of the nephrotic syndrome, reverse sex ratios, lower serum cholesterol, higher mortality rate and sickle cell complications rather than chronic renal failure as the major cause of death.     

Compaction Behaviour of Musol, A New Direct Compression Vehicle

The compaction characteristics of Musol, a new autocompressible vehicle derived through chemical modification of mucuna gum was investigated. Avicel PH 101, Zeparox and Encompress were used as reference tablet vehicles. Values of the mean yield stress derived from the analysis of Heckel plots indicate that Musol consolidates principally by plastic deformation, The effect of lubrication and recompression on friability, tensile strength and re-working potential of the tablets prepared with the vehicles were determined. While Avicel PH 101 yielded the strongest tablets, Musol showed the highest re-working potential for lubricated and un-lubricated slugs. On the basis of friability, tensile Values of strength and re-working potential, Musol than the grades of Zeparpx or Encompress performed better used in the study.     

Chromosome breaks and sister chromatid exchanges in albinos in Nigeria

The prevalence of squamous cell carcinoma of the skin in albinos reaches approximately 90% in patients over 20 years of age in the vicinity of Enugu, Nigeria. Chromosome breaks and sister chromatid exchanges (SCE) were evaluated in tyrosinase-positive oculocutaneous albinos and pigmented controls of Ibo extraction who were life-long residents of Nigeria. No difference in the frequency of chromosomal breaks in 14 albinos compared to 6 pigmented controls, and no differences in the frequency of SCE in 9 albinos compared to 3 controls could be detected. Increased chromosomal abnormalities in lymphocytes do not appear to be assoicated with albinism or fulminating skin cancer present in albinos in the tropics.