Solid dispersions: formulation, characterisation, permeability and genomic evaluation

Poor water solubility is characterised by low dissolution rate and consequently reduced bioavailability. Formulation of solid dispersion of the drug has attracted considerable interest as a means of improving dissolution process of a range of poorly water soluble drugs. This current study investigates the formulation of solid dispersion for a range of poorly water soluble drugs with varying physicochemical properties including paracetamol, sulphamethoxazole, phenacetin, indomethacin, chloramphenicol, phenylbutazone and succinylsulphathiazole. Solid dispersions were prepared using various drugs to polymer ratios. PEG 8000 was selected as a carrier in the solid dispersions. The study revealed that inclusion of drug within the polymeric matrix, ratio of drug to polymer and physicochemical properties of the drug molecules enhance the dissolution rate. Characterisations of the solid dispersions were performed using DSC, FTIR and SEM. These studies revealed that all seven drugs were present in the amorphous form within the solid dispersions and there was a lack of interaction between the PEG 8000 and drug. Stability studies for solid dispersions showed that all seven drugs studied were unstable at accelerated conditions (40°C±2°C/75%RH±5%RH) whereas, they were found to be stable for 12 months at room conditions. Permeability of indomethacin, phenacetin, phenylbutazone and paracetamol were higher for solid dispersions as compared to drug alone across Caco-2 cell monolayers. From the cell uptake studies it was shown that PEG 8000 enhanced rhodamine123 uptake which suggested that PEG 8000 may increase the permeability of these drugs in solid dispersions. Gene expression profiles analyzing the expression changes in the ABC and solute carrier transporter during permeability studies.ABCA10, ABCB4, ABCC12, SLC12A6, MCT13, SLC22A12 and SLC6A6 gene expression were increased by indomethacin alone whereas solid dispersion of indomethacin resulted in a slight increase in expression. ABCC12 and SAMC gene expression was increased in case of paracetamol alone but slightly increased when exposed to solid dispersion of paracetamol.

The effect of thyroid hormones an growth and metabolism of two species of teleost fish

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY WITH PRIOR ARRANGEMENT

The role of accounting in planning and control: with special reference to the Egyptian iron and steel company Hadisolb

This thesis investigates the role of accounting in planning and control in the Egyptian Iron and Steel Company "Hadisolb". The hypothesis is that there should be planning and control at appropriate levels, with a significant accounting involvement, In an organisation such as the Egyptian Iron and Steel Company "Hadisolb" . Part One of the thesis explains the role of accounting in planning and control, with special emphasis on its role in long-range corporate planning and control. Parts Two and Three review the history of the Egyptian Iron and Steel Company "Hadisolb", its organisation and structure, also the role of accounting in its planning and control arrangements, together with comments and criticisms concerning this. Part Four is mainly recommendations for alterations or improvements in planning and control in Hadisolb. This includes a suggested planning and organisation structure, physical and cost control reporting structures.

The compressive creep and load relaxation properties of a series of high aluminium zinc-based alloys

A new family of commercial zinc alloys designated as ZA8, ZA12, and ZA27 and high damping capacity alloys including Cosmal and Supercosmal and aluminium alloy LM25 were investigated for compressive creep and load relaxation behaviour under a series of temperatures and stresses. A compressive creep machine was designed to test the sand cast hollow cylindrical test specimens of these alloys. For each compressive creep experiment the variation of creep strain was presented in the form of graphs plotted as percentage of creep strain () versus time in seconds (s). In all cases, the curves showed the same general form of the creep curve, i.e. a primary creep stage, followed by a linear steady-state region (secondary creep). In general, it was observed that alloy ZA8 had the least primary creep among the commercial zinc-based alloys and ZA27 the greatest. The extent of primary creep increased with aluminium content to that of ZA27 then declined to Supercosmal. The overall creep strength of ZA27 was generally less than ZA8 and ZA12 but it showed better creep strength than ZA8 and ZA12 at high temperature and high stress. In high damping capacity alloys, Supercosmal had less primary creep and longer secondary creep regions and also had the lowest minimum creep rate among all the tested alloys. LM25 exhibited almost no creep at maximum temperature and stress used in this research work. Total creep elongation was shown to be well correlated using an empirical equation. Stress exponent and activation energies were calculated and found to be consistent with the creep mechanism of dislocation climb. The primary α and β phases in the as-cast structures decomposed to lamellar phases on cooling, with some particulates at dendrite edges and grain boundaries. Further breakdown into particulate bodies occurred during creep testing, and zinc bands developed at the highest test temperature of 160°C. The results of load relaxation testing showed that initially load loss proceeded rapidly and then deminished gradually with time. Load loss increased with temperature and almost all the curves approximated to a logarithmic decay of preload with time. ZA alloys exhibited almost the same load loss at lower temperature, but at 120°C ZA27 improved its relative performance with the passage of time. High damping capacity alloys and LM25 had much better resistance to load loss than ZA alloys and LM25 was found to be the best against load loss among these alloys. A preliminary equation was derived to correlate the retained load with time and temperature.

Catalytic pyrolysis of rice husk for bio-oil production

Catalytic pyrolysis experiments have been carried out on Brunei rice husk (BRH) to obtain bio-oil using a fixed-bed pyrolysis rig. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) were used as the catalysts for the catalytic pyrolysis experiments and comparison was done to analyse the changes in the bio-oil properties and yield. Properties of the liquid catalytic and non-catalytic bio-oil were analysed in terms of water content, pH, acid number, viscosity, density and calorific value. The bio-oil chemical composition shows that ZSM-5 increases the production of aromatic hydrocarbons and light phenols, whilst Al-MCM-41 reduces the acetic acid production. The catalytic runs increased the calorific value and water content in the bio-oil, whilst viscosity, density and acid number is decreased. © 2012 Elsevier B.V. All rights reserved.

Experimental investigation of inter-modal cross-gain modulation and transient effects in a two mode group erbium doped fiber amplifier

We report what we believe to be the first experimental study of inter-modal cross-gain modulation and associated transient effects as different spatial modes and wavelength channels are added and dropped within a two-mode amplifier for SDM transmission.

First demonstration of 2μm data transmission in a low-loss hollow core photonic Bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time.

Thermochemical characterisation of agricultural wastes from West Africa

Thermochemical characterisation of agricultural biomass wastes from West African region has been carried out and their potential use as feedstock in thermochemical conversion processes determined. Proximate, ultimate, structural compositions, calorific values, thermogravimetry (TGA) and derivative thermogravimetry (DTG) analyses were carried out on corn straw and cobs, rice straw and husks, cocoa pod, jatropha curcas and moringa olifiera seed cakes, parinari polyandra fruit shell and sugarcane bagasse. Moringa olifiera seed cakes and cocoa pods were found to contain the highest moisture contents. Rice straw was found to contain a high ash content of 45.76. wt.%. The level of nitrogen and sulphur in all the samples were very low. Rice husk was found to have the highest lignin contents while corn cob low lignin contents indicate a potential feedstock source for quality bio-oil production using thermochemical process. © 2013.

Economic efficiency of smallholder maize producers in Western Kenya:a DEA meta-frontier analysis

Maize is the main staple food for most Kenyan households, and it predominates where smallholder, as well as large-scale, farming takes place. In the sugarcane growing areas of Western Kenya, there is pressure on farmers on whether to grow food crops, or grow sugarcane, which is the main cash crop. Further, with small and diminishing land sizes, the question of productivity and efficiency, both for cash and food crops is of great importance. This paper, therefore, uses a two-step estimation technique (DEA meta-frontier and Tobit Regression) to highlight the inefficiencies in maize cultivation, and their causes in Western Kenya.

Ultra-long mode-locked Er-droped fibre lasers

The development of ultra-long (UL) cavity (hundreds of meters to several kilometres) mode-locked fibre lasers for the generation of high-energy light pulses with relatively low (sub-megahertz) repetition rates has emerged as a new rapidly advancing area of laser physics. The first demonstration of high pulse energy laser of this type was followed by a number of publications from many research groups on long-cavity Ytterbium and Erbium lasers featuring a variety of configurations with rather different mode-locked operations. The substantial interest to this new approach is stimulated both by non-trivial underlying physics and by the potential of high pulse energy laser sources with unique parameters for a range of applications in industry, bio-medicine, metrology and telecommunications. It is well known, that pulse generation regimes in mode-locked fibre lasers are determined by the intra-cavity balance between the effects of dispersion and non-linearity, and the processes of energy attenuation and amplification. The highest per-pulse energy has been achieved in normal-dispersion UL fibre lasers mode-locked through nonlinear polarization evolution (NPE) for self-modelocking operation. In such lasers are generated the so-called dissipative optical solitons. The uncompensated net normal dispersion in long-cavity resonatorsusually leads to very high chirp and, consequently, to a relatively long duration of generated pulses. This thesis presents the results of research Er-doped ultra-long (more than 1 km cavity length) fibre lasers mode-locked based on NPE. The self-mode-locked erbium-based 3.5-km-long all-fiber laser with the 1.7 µJ pulse energy at a wavelength of 1.55 µm was developed as a part of this research. It has resulted in direct generation of short laser pulses with an ultralow repetition rate of 35.1 kHz. The laser cavity has net normal-dispersion and has been fabricated from commercially-available telecom fibers and optical-fiber elements. Its unconventional linear-ring design with compensation for polarization instability ensures high reliability of the self-mode-locking operation, despite the use of a non polarization-maintaining fibers. The single pulse generation regime in all-fibre erbium mode-locking laser based on NPE with a record cavity length of 25 km was demonstrated. Modelocked lasers with such a long cavity have never been studied before. Our result shows a feasibility of stable mode-locked operation even for an ultra-long cavity length. A new design of fibre laser cavity – “y-configuration”, that offers a range of new functionalities for optimization and stabilization of mode-locked lasing regimes was proposed. This novel cavity configuration has been successfully implemented into a long-cavity normal-dispersion self-mode-locked Er-fibre laser. In particular, it features compensation for polarization instability, suppression of ASE, reduction of pulse duration, prevention of in-cavity wave breaking, and stabilization of the lasing wavelength. This laser along with a specially designed double-pass EDFA have allowed us to demonstrate anenvironmentally stable all-fibre laser system able to deliver sub-nanosecond high-energy pulses with low level of ASE noise.

Experimental investigation of inter-modal cross-gain modulation and transient effects in a two mode group erbium doped fiber amplifier

We report what we believe to be the first experimental study of inter-modal cross-gain modulation and associated transient effects as different spatial modes and wavelength channels are added and dropped within a two-mode amplifier for SDM transmission.

Catalytic intermediate pyrolysis of Brunei rice husk for bio-oil production

Rice husks from Brunei were subjected via intermediate pyrolysis for bio-oil production. Two main objectives were set out for this study. The application of intermediate pyrolysis on Brunei rice husk for the production of bio-oil is the main objective of this experiment. Characterisation of the rice husks was inclusive as a pre-requisite step to assess the suitability as feedstock for production of liquid fuels. Following on from the characterisation results, a temperature of 450°C was established as the optimum temperature for the production of bio-oil. A homogenous bio-oil was obtained from the pyrolysis of dry rice husk, and the physicochemical properties and chemical compositions were analysed. The second objective is the introduction of catalysts into the pyrolysis process which aims to improve the bio-oil quality, and maximise the desired liquid bio-oil properties. The incorporation of the catalysts was done via a fixed tube reactor into the pyrolysis system. Ceramic monoliths were used as the catalyst support, with montmorillonite clay as a binder to attach the catalysts onto the catalyst support. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) together with its combination were adopted as catalysts. Proposed criterions dictated the selection of the best catalysts, subsequently leading to the optimisation process for bio-oil production. ZSM-5/Al-MCM-41 proved the most desirable catalyst, which increases the production of aromatics and phenols, decreased the organic acids and improved the physicochemical properties such as the pH, viscosity, density and H:C molar ratios. Variation in the ratio and positioning of both catalysts were the significant key factor for the catalyst optimisation study.

Plasma irisin levels predict telomere length in healthy adults

The ageing process is strongly influenced by nutrient balance, such that modest calorie restriction (CR) extends lifespan in mammals. Irisin, a newly described hormone released from skeletal muscles after exercise, may induce CR-like effects by increasing adipose tissue energy expenditure. Using telomere length as a marker of ageing, this study investigates associations between body composition, plasma irisin levels and peripheral blood mononuclear cell telomere length in healthy, non-obese individuals. Segmental body composition (by bioimpedance), telomere length and plasma irisin levels were assessed in 81 healthy individuals (age 43∈±∈15.8 years, BMI 24.3∈±∈2.9 kg/m2). Data showed significant correlations between log-transformed relative telomere length and the following: age (p∈<∈0.001), height (p∈=∈0.045), total body fat percentage (p∈=∈0.031), abdominal fat percentage (p∈=∈0.038) , visceral fat level (p∈<∈0.001), plasma leptin (p∈=∈0.029) and plasma irisin (p∈=∈0.011), respectively. Multiple regression analysis using backward elimination revealed that relative telomere length can be predicted by age (b∈=∈-0.00735, p∈=∈0.001) and plasma irisin levels (b∈=∈0.04527, p∈=∈0.021). These data support the view that irisin may have a role in the modulation of both energy balance and the ageing process. © 2014 The Author(s).

WDM transmission at 2μm over low-loss hollow core photonic bandgap fiber

World's first demonstration of WDM transmission in a HC-PBGF at the predicted low loss region of 2m is presented. A total capacity of 16 Gbit/s is achieved using 1×8.5 Gbit/s and 3×2.5 Gbit/s channels modulated using NRZ OOK over 290 meters of hollow core fiber. © 2013 OSA.