A one-way dissection of high-order compact scheme for the solution of 2D Poisson equation

We present a one-way dissection formulation of high-order compact scheme for the solution of 2D Poisson equation. One-way dissection is a type of matrix reordering, divide and conquers procedure. Efficient and concise compact schemes of 4th and 6th orders are derived using the truncation errors of the Taylors’ series expansion of the governing equation. The system is split into sub-domains and each sub-domain is treated separately. Two test problems are solved to show the fourth order performance of the scheme. The direct method is used to achieve a quick solution to the problems

Outcome of gastroplasty and gastric bypass in a single centre in the UK

<p>Abstract</p> <p>Background</p> <p>Morbid obesity is defined as BMI>40 kg/m². It affects 124,000 men and 412,000 women in England and Wales (NICE, July 2002). According to NICE guidelines, Bariatric surgery is indicated if the treatments for obesity such as exercise, diet and drugs fail. Procedures include laparoscopic gastric banding (LGB), vertical banded gastroplasty (VBG), and Gastric Bypass (GB).</p> <p>Aims</p> <p>The aim of this audit was to determine if NICE guidelines on the use of Bariatric surgery in the Manor Hospital, Walsall was being adhered to. <b>Secondary aims were </b>also to establish if Bariatric surgery is achieving its goal in the long-term and if weight reduction is being maintained in this group of patients.</p> <p>Methods</p> <p>A retrospective cohort study was carried out on patients who underwent Bariatric surgery between 1990 and 2004. Retrieved records were scrutinised and the following parameters were collated: pre-operative morbidities, intra and post-operative complication rates and weight reduction on follow-up.</p> <p>Results</p> <p>129 patients were operated on in the 14 year period. For VBG, 40 out of 105 patients had weight gain by the 5th follow-up visit. This compared with 5 out of 18 patients after the same timescale for the GB group and 1 out of 6 in the LGB group. The most common post-operative complication was stenosis (28% of VBG group).</p> <p>Conclusion</p> <p>Bariatric surgery is relatively safe as an intervention for morbid obesity. Weight loss however is not maintained in the long term. VBG and LGB are short term interventions. Further research is required to look into the merits of gastric bypass surgery.</p

Structural integrity and dispersion characteristics of carbon nanotubes in titanium-based alloy

Abstract: Over the years, carbon nanotubes have attracted much attention in engineering materials research due to their outstanding and superlative properties. Owing to the demands for lightweight materials with excellent mechanical and thermal properties for diverse industrial applications encouraged the incorporation of carbon nanotubes into titanium alloys. However, there are various challenges associated with the incorporation of carbon nanotubes into titanium alloys which includes; uniform dispersion and retaining the structural integrity of carbon nanotubes after dispersion. Past works have emphasized the importance of homogeneous dispersion with less structural damage to the carbon nanotubes in the various metal matrix. Therefore, this research focused on dispersion of 0.5 wt. % multiwalled carbon nanotubes in Ti6Al4V using low energy ball milling and evaluating the dispersion characteristics and structural integrity of MWCNTs in Ti6Al4V after dispersion. Various characterization techniques such as high-resolution transmission electron microscopy, scanning electron microscopy, X-Ray diffraction and Raman spectroscopy were adopted to ascertain the microstructural evolution, morphology, interfacial reaction and structural integrity of the carbon nanotubes in the Ti6Al4V powders before and after dispersion. The results indicated homogeneous dispersion of carbon nanotubes with less structural damages which are confirmed from the (ID/IG) ratio of the Raman spectra and the TEM images

Effect of sintering parameters on the densification and hardness of NiAl-CNTs composite

Abstract : Nickel aluminides have attracted considerable interest in the past few decades owing to its unique properties. In this work, nickel aluminide (NiAl) was formed in-situ during spark plasma sintering of admixed powders of nickel, aluminium and carbon nanotubes (CNTs) after ball milling. 1 wt % CNTs was incorporated into the intermetallic matrix and the effect of varying sintering parameters investigated, particularly the sintering temperature and pressure. Results showed that a combination of higher sintering temperature with lower pressure yielded better results than lower sintering temperature and higher pressure. Thus the former parameters yielded better densification and subsequently higher micro hardness values of the NiAl-CNTs composites as compared to the latter

Effect of milling parameters on the dispersion characteristics of multi-walled carbon nanotubes in transition metal oxides

Abstract: In this research investigation on milling parameters to achieve uniform dispersion of multi-walled carbon nanotubes (MWCNTs) was conducted. High-energy ball milling (HEBM) technique was adopted to disperse 1 wt. % MWCNTs in titanium and manganese oxides with ball to powder ratio (BPR) of 10:1 at 6 and 9 hours milling times. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the as-received MWCNTs and admixed composite powders. The results indicated that HEBM was an effective route to disperse MWCNTs in transition metal oxides. In addition, the characteristics of admixed powders evidently showed that the increase of milling time effectively dispersed the MWCNTs in titanium and manganese oxide respectively, however deformation of sidewalls of MWCNTs was observed due to harsh milling conditions that resulted on non-sp2 defects in the MWCNTs

Enhancing bioenergy production from food waste by in situ biomethanation: Effect of the hydrogen injection point

The increasing rate of food waste (FW) generation around the world is a growing environmental concern, notwithstanding, its valorisation through anaerobic digestion (AD) makes it a potential resource. Moreover, there is a growing demand to optimise the biomethane from AD for gas‐to‐grid (GtG) and vehicular applications. This has spurred researches on hydrogen gas (H2) injection into AD systems to enhance the biological conversion of H2 and carbon dioxide (CO2) to methane (CH4), a process known as biomethanation. A simplistic approach for biomethanation is to add H2 directly into working AD reactors (in situ biomethanation). However, a competition for the injected H2 towards other biological reactions besides H2/CO2 conversion to CH4 could follow, thus, reducing the efficiency of the system. Hence, this study was conducted to understand how different H2 injection points would affect H2/CO2 conversion to CH4 during FW in situ biomethanation, to identify an optimal injection point. Experiments were designed using H2 equivalent to 5% of the head‐space of the AD reactor at three injection points representing different stages of AD: before volatile fatty acids (VFA) accumulation, during VFA accumulation and at depleted VFA intermediates. Lower potential for competitive H2 consumption before the accumulation of VFA enabled a high H2/CO2 conversion to CH4. However, enhanced competition for soluble substrates during VFA accumulation reduced the efficiency of H2/CO2 conversion to CH4 when H2 was added at this stage. In general, 12%, 4% and 10% CH4 increases as well as 39%, 25% and 34% CO2 removal were obtained for H2 added before VFA accumulation, during VFA accumulation and at depleted VFA intermediates, respectively. For immediate integration of biomethanation with existing AD facilities, it is suggested that the required H2 be obtained biologically by dark fermentation

Biomechanical and Physical Properties Selection of Ti-Ha-CaCO3 Biocomposite Prostheses for Replacement of Bone Atrophy

Traditional prosthetic materials often lack the desired properties to mimic the mechanical behaviour of natural bone, leading to complications and reduced implant longevity. This study aims to conduct a biomechanical and physical properties selection analysis for biocomposite prostheses' suitable for replacing bone atrophy. This involves evaluating the mechanical properties of developed biocomposites with different structures (dense, porous and gradient) to ensure compatibility with the mechanical properties of bone. The radar chart was adopted to compare and evaluate the mechanical strength of various biocomposite implants and identify the most suitable prosthesis for load-bearing bone replacement. The study utilises powder metallurgy, scanning electron microscopy (SEM), and ImageJ software to produce and characterise the pore size distribution of the biocomposites, respectively. The findings of this study revealed the gradient and porous biocomposites exhibited desired mechanical properties with porosity of 20.67 and 27.72 % pore size up to 134 and 256 μm, compressive strength of 174 and 149.29 MPa and compressive modulus of 30.42 and 28.3 GPa respectively. The SEM analysis, coupled with pore size distribution and porosity percentage measurements, offers valuable information for designing and fabricating biomaterials with enhanced properties. The gradient biocomposite was identified to be the best sample for load-bearing bone replacements by the selection analysis because of its high compressive strength and low modulus, which is within the established cortical bone mechanical properties

Skin Cancers Among Albinos at a University Teaching Hospital in Northwestern Tanzania: A Retrospective Review of 64 Cases.

Skin cancers are a major risk associated with albinism and are thought to be a major cause of death in African albinos. The challenges associated with the care of these patients are numerous and need to be addressed. The aim of this study was to outline the pattern and treatment outcome of skin cancers among albinos treated at our centre and to highlight challenges associated with the care of these patients and proffer solutions for improved outcome. This was a retrospective study of all albinos with a histopathological diagnosis of skin cancer seen at Bugando Medical Centre from March 2001 to February 2010. Data collected were analyzed using descriptive statistics. A total of 64 patients were studied. The male to female ratio was 1.5:1. The median age of patients was 30 years. The median duration of illness at presentation was 24 months. The commonest reason for late presentation was financial problem. Head and the neck was the most frequent site afflicted in 46(71.8%) patients. Squamous cell carcinoma was the most common histopathological type in 75% of cases. Surgical operation was the commonest modality of treatment in 60 (93.8%) patients. Radiotherapy was given in 24(37.5%) patients. Twenty-seven (42.2%) of the patients did not complete their treatment due to lack of funds. Local recurrence following surgical treatment was recorded in 6 (30.0%) patients. Only thirty-seven (61.7%) patients were available for follow-up at 6-12 months and the remaining patients were lost to follow-up. Skin cancers are the most common cancers among albinos in our environment. Albinism and exposure to ultraviolet light appears to be the most important risk factor in the development of these cancers. Late presentation and failure to complete treatment due to financial difficulties and lack of radiotherapy services at our centre are major challenges in the care of these patients. Early institution of preventive measures, early presentation and treatment, and follow-up should be encouraged in this population for better outcome