22 research outputs found
Peritoneal patch for retrohepatic vena cava reconstruction during major hepatectomy: how I do it
No full textPeritoneal patch for retrohepatic vena cava reconstruction during major hepatectomy: how I do it
No full textInvestigation into laser re-melting of inconel 625 HVOF coating blended with WC
No full textHigh velocity oxy-fuel (HVOF) spraying of Diamalloy 1005 powders mixed with WC particles onto steel (304) is considered and laser re-melting of the resulting coatings is examined. Laser re-melting process is modeled to determine the melt layer thickness while temperature increase is formulated using the Fourier heating law. The morphological and metallurgical analyses prior and post laser re-melting process are carried out using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) technique is used to determine the residual stress developed in the coating while the analytical formulation is adopted to predict the residual stress levels at the coating base material interface. The indentation tests are carried out to determine the Young’s modulus and fracture toughness of the coating prior to laser re-melting. Corrosion resistance of coating is measured using potentiodynamic polarization technique prior and post laser treatment process. The predictions of the melt layer thickness are in good agreement with experimental results. The presence of WC particles modifies temperature rise and its gradient in the coating while affecting the Young’s modulus, residual stress levels, and fracture toughness of the coating. The differences in the thermal properties of Inconel 625 powders and WC particles result in formation of small size cellular structure through polyphase solidification. WC dissolution in the central region of the large polycrystalline cells is observed due to the loss of carbon through carbonic gas formation. The results of corrosion tests prevail that significant improvement of corrosion resistance can be achieved after laser treatment process
A retrospective multicenter analysis on redo-laparoscopic anti-reflux surgery: conservative or conversion fundoplication?
No full textBackgroundNearly 20% of patients who undergo hiatal hernia (HH) repair and anti-reflux surgery (ARS) report recurrent HH at long-term follow-up and may be candidates for redo surgery. Current literature on redo-ARS has limitations due to small sample sizes or single center experiences. This type of redo surgery is challenging due to rare but severe complications. Furthermore, the optimal technique for redo-ARS remains debatable. The purpose of the current multicenter study was to review the outcomes of redo-fundoplication and to identify the best ARS repair technique for recurrent HH and gastroesophageal reflux disease (GERD).MethodsData on 975 consecutive patients undergoing hiatal hernia and GERD repair were retrospectively collected in five European high-volume centers. Patient data included demographics, BMI, techniques of the first and redo surgeries (mesh/type of ARS), perioperative morbidity, perioperative complications, duration of hospitalization, time to recurrence, and follow-up. We analyzed the independent risk factors associated with recurrent symptoms and complications during the last ARS. Statistical analysis was performed using GraphPad Prism((R)) and R software((R)).ResultsSeventy-three (7.49%) patients underwent redo-ARS during the last decade; 71 (98%) of the surgeries were performed using a minimally invasive approach. Forty-two (57.5%) had conversion from Nissen to Toupet. In 17 (23.3%) patients, the initial Nissen fundoplication was conserved. The initial Toupet fundoplication was conserved in 9 (12.3%) patients, and 5 (6.9%) had conversion of Toupet to Nissen. Out of the 73 patients, 10 (13%) underwent more than one redo-ARS. At 8.5 (1-107) months of follow-up, patients who underwent reoperation with Toupet ARS were less symptomatic during the postoperative period compared to those who underwent Nissen fundoplication (p=0.005, OR 0.038). Patients undergoing mesh repair during the redo-fundoplication (21%) were less symptomatic during the postoperative period (p=0.020, OR 0.010). The overall rate of complications (Clavien-Dindo classification) after redo surgery was 11%. Multivariate analysis showed that the open approach (p=0.036, OR 1.721), drain placement (p=0.0388, OR 9.308), recurrence of dysphagia (p=0.049, OR 8.411), and patient age (p=0.0619, OR 1.111) were independent risk factors for complications during the last ARS.ConclusionsFailure of ARS rarely occurs in the hands of experienced surgeons. Redo-ARS is feasible using a minimally invasive approach. According to our study, in terms of recurrence of symptoms, Toupet fundoplication is a superior ARS technique compared to Nissen for redo-fundoplication. Therefore, Toupet fundoplication should be considered in redo interventions for patients who initially underwent ARS with Nissen fundoplication. Furthermore, mesh repair in reoperations has a positive impact on reducing the recurrence of symptoms postoperatively
Processing of advanced Al/SiC particulate metal matrix composites under intensive shearing – A novel rheo process
No full textParticulate Metal Matrix Composites (PMMCs) have attracted interest for application in numerous fields. The current processing methods often produce agglomerated particles in the ductile matrix and as a result these composites exhibit extremely low ductility. The key idea to solve the current problem is to adopt a novel Rheo-process allowing the application of sufficient shear stress () on particulate clusters embedded in liquid metal to overcome the average cohesive force or the tensile strength of the cluster. In this study, cast A356/SiCp composites were produced using a conventional stir casting technique and a novel Rheo-process. The microstructure and properties were evaluated. The adopted Rheo-process significantly improved the distribution of the reinforcement in the matrix. A good combination of improved Ultimate Tensile Strength (UTS) and tensile elongation (ε) is obtained
Solidification behaviour and mechanical properties of cast Mg-alloys and Al-based particulate metal matrix composites under intensive shearing
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Magnesium alloys, as the lightest of all structural metallic materials, and aluminium-based particulate metal matrix composites (PMMCs), offering unified combination of metallic and ceramic properties, have attracted increased interest from the automotive, aerospace, electronic and recreation industries. Current processing technologies for PMMCs do not achieve a uniform distribution of fine-sized reinforcements and produce agglomerated particles in the ductile matrix, which are detrimental to the ductility. At the same time, molten magnesium alloys contain impurities and oxides and when cast conventionally, the final components usually exhibit a coarse and non-uniform microstructure with various casting defects. The key idea in this thesis has been to adopt a novel intensive melt conditioning process, allowing the application of sufficient shear stress that would disperse solid particles present in the melt and offer unique solidification behaviour, improved fluidity and die-filling during casting. The Melt Conditioned High Pressure Die Casting (MC-HPDC) process, where intensive shearing is directly imposed on the alloy melt, which is then cast by the conventional HPDC process, has been used to produce PMMC and magnesium alloy castings. The MC-HPDC process for PMMCs leads to a uniform dispersion of the reinforcement in the matrix, confirmed by quantitative statistical analysis, and increased mechanical performance as indicated by an increase in the hardness and the tensile properties of the composites. We describe a solidification path for aluminium containing magnesium alloys, where intensive shearing prior to casting leads to effective dispersion of solid oxide particles, which then effectively act as nucleation sites for magnesium grains, resulting in significant grain refinement. The MC-HPDC processed magnesium castings have a significantly refined microstructure, with reduced porosity levels and casting defects. Evaluation of the mechanical properties of the castings reveals the beneficial effect of intensive shearing. After careful optimization, the MC-HPDC process shows promising potential for the direct recycling of high purity magnesium die casting scrap, producing casting with mechanical properties comparable to those of primary magnesium alloys
Aetiology and treatment of epidermal depigmentory disorder in humans
No full textThe epidermal depigmentary trigger in humans at post-natal level may occur with the toxification of skin organ with the endogenously produced melanocytotoxic hydrogen peroxide and subsequent formation of hydrogen peroxide- melanolipoprotein conjugate involving the hydrogen bonding of complementary hydroxyl and carbonyl molecular surfaces of these biosignitures respectively. The condition is multifactorial but reversible. The structural and functional degeneration of melanocytes under the acquired condition never occur. The molecular conjugation theory on the aetiology and line of treatment of the epidermal depigmentary disorder (recoined as hepato-epidermal syndrome HES) has been proposed. The inherent sulfoxides of Allium cepa have been found as the renaturant of HES condition with the capacity to dislodge the denaturant hydrogen peroxide forming stronger hydrogen bonding with hydrogen peroxide than that of carbonyl molecular surface of melanolipoprotein, the epidermal colour determinant. The orally and topically defined plant based combined therapy advances the recovery time of HES condition
Enhancing the efficacy of cytotoxic agents for cancer therapy using photochemical internalisation.
No full textPhotochemical internalisation (PCI) is a technique for improving cellular delivery of certain bioactive agents which are prone to sequestration within endolysosomes. There is a wide range of agents suitable for PCI-based delivery including toxins, oligonucleotides, genes and immunoconjugates which demonstrates the versatility of this technique. The basic mechanism of PCI involves triggering release of the agent from endolysosomes within the target cells using a photosensitiser which is selectively retained with the endolysosomal membranes. Excitation of the photosensitiser by visible light leads to disruption of the membranes via photooxidative damage thereby releasing the agent into the cytosol. This treatment enables the drugs to reach their intended subcellular target more efficiently and improves their efficacy. In this review we summarise the applications of this technique with the main emphasis placed on cancer chemotherapy
Laser surface modification of Ti alloys
No full textThe laser surface engineering of titanium alloys has been developed over the past 30 years to produce a modified layer up to 1mm depth, thicker than alternative techniques. CW C02 lasers have been the main lasers used for both surface cladding and alloying. Much of the early work was based on laser nitriding forming titanium nitrides throughout the molten pool. Subsequent alloying developments have included the incorporation of carbides, nitrides, oxides and silicides, and also intermetallics and rare earths, added as powders. Laser processing can now tailor surfaces with superior tribological and erosion resistant properties compared to the untreated titanium alloys
