Computer Simulation of Hydrostatic Co-Extrusion of Bimetallic Compounds.

A study of hydrostatic co-extrusion of a hard-core/soft-clad bi-metallic compound has been conducted. The research employs the Sachs\u27 boring-out technique to determine the residual stress distribution in a hydrostatically co-extruded copper-clad Gildcop composite. A parallel simulation of the residual stress distribution in such composites extruded to extrusion ratios of 2.25, 4.0, and 7.5 was conducted using the ABAQUS finite element code. The version of the code employed uses an elastic-plastic constitutive law for material behavior and does not simulate deformation heating effects. Data for the mechanical properties were obtained experimentally by constant true strain-rate tests on material identical to that used in the extrusion experiments. The results indicate that the extrusion pressure varies linearly with the natural logarithm of the extrusion ratio. The simulation results obtained for this pressure, however, are generally higher than those found in experiments. Comparison of the experimental and numerical results of the residual stresses indicate that although the two results are qualitatively similar, they are quantitatively different. In all cases, the experimental results were much lower than those of numerical calculations, implying that some recovery has occurred during the extrusion process. The investigation shows, however, that finite element analysis in conjunction with experimental measurements can be applied successfully to predict and verify the qualitative residual stress patterns developed in hydrostatically extruded products

Finite element modelling and image reconstruction in single and multi-frequency electrical impedance tomography.

Electrical impedance tomography (EIT) is an imaging technique that aims to reconstruct the internal conductivity distribution of a body, based on the electrical measurements taken on its periphery. While relatively new it has received attention as a possible new medical imaging technique which offers non-hazardous applications and low-cost instrumentation.To understand the full potential of this new mode of imaging, a numerical modelling method has been used in order to investigate the behaviour of an EIT system. Using this mode of analysis, it is possible to simulate many experiments that otherwise physically would be very time consuming and expensive. Such investigation will include the effect and quantification of various physical conditions which have effects on the obtained boundary voltages of an EIT system. An aim of EIT is the ability to reconstruct accurate images of internal conductivity distributions from the measured boundary voltages. Image reconstruction in EIT using the sensitivity algorithm is generally based on the assumption that the initial conductivity distribution of the body being imaged is uniform. The technique of image reconstruction using the sensitivity algorithm is described and reconstructed images are presented. Improvements in image quality and accuracy are demonstrated when accurate a-priori 'anatomical' information, in the form of a model of the distribution of conductivity within the region to be imaged, are used. In practice correct a-priori information is not available, for example, the conductivity values within the various anatomical regions will not be known. An iterative algorithm is presented which allows the conductivity parameters of the a-priori model to be calculated during image reconstruction. Multi-frequency EIT is a modified approach of the single frequency method by which tissue characterisation has been proposed by imaging the internal conductivity of region over a range of frequencies. However, due to instrumentation drawbacks, only the real parts of the boundary voltages are presently measured. These real only voltages have sofar (in practice) been used to reconstruct images of the changes in internal conductivity of a region with frequency. The penalty for ignoring the imaginary parts of the data are presented and results obtained show that to accurately image the internal conductivity of a region, not only complex data are needed, but also some a-priori information about the region may be necessary

Finite element modelling and image reconstruction in single and multi-frequency electrical impedance tomography.

Electrical impedance tomography (EIT) is an imaging technique that aims to reconstruct the internal conductivity distribution of a body, based on the electrical measurements taken on its periphery. While relatively new it has received attention as a possible new medical imaging technique which offers non-hazardous applications and low-cost instrumentation.To understand the full potential of this new mode of imaging, a numerical modelling method has been used in order to investigate the behaviour of an EIT system. Using this mode of analysis, it is possible to simulate many experiments that otherwise physically would be very time consuming and expensive. Such investigation will include the effect and quantification of various physical conditions which have effects on the obtained boundary voltages of an EIT system. An aim of EIT is the ability to reconstruct accurate images of internal conductivity distributions from the measured boundary voltages. Image reconstruction in EIT using the sensitivity algorithm is generally based on the assumption that the initial conductivity distribution of the body being imaged is uniform. The technique of image reconstruction using the sensitivity algorithm is described and reconstructed images are presented. Improvements in image quality and accuracy are demonstrated when accurate a-priori 'anatomical' information, in the form of a model of the distribution of conductivity within the region to be imaged, are used. In practice correct a-priori information is not available, for example, the conductivity values within the various anatomical regions will not be known. An iterative algorithm is presented which allows the conductivity parameters of the a-priori model to be calculated during image reconstruction. Multi-frequency EIT is a modified approach of the single frequency method by which tissue characterisation has been proposed by imaging the internal conductivity of region over a range of frequencies. However, due to instrumentation drawbacks, only the real parts of the boundary voltages are presently measured. These real only voltages have sofar (in practice) been used to reconstruct images of the changes in internal conductivity of a region with frequency. The penalty for ignoring the imaginary parts of the data are presented and results obtained show that to accurately image the internal conductivity of a region, not only complex data are needed, but also some a-priori information about the region may be necessary

Assessment of normal hemodynamic profile of mechanical pulmonary prosthesis by doppler echocardiography: a prospective cross-sectional study

OBJECTIVES: Very few reports have described the Doppler-derived echocardiographic parameters for mechanical pulmonary valve prosthesis (MPVP). This study aims to describe the normal Doppler hemodynamic profile of MPVP using Doppler echocardiography. METHODS: The current prospective, single center observational study enrolled 108 patients who underwent pulmonary valve replacement (PVR) surgery for the first time and had a normally functioning prosthesis post-operation. The hemodynamic performance of MPVPs, considering flow dependent and flow independent parameters, was evaluated at two follow-up points, at week one and week four post-operation. All assessments were conducted by an experienced echocardiographer. RESULTS: The mean age (±SD) of the participants was 26.4 (±8.98). Tetralogy of Fallot (ToF) was the most common underlying disease leading to PVR, with a prevalence of 88. At first week post-operation, measurement of indices reported the following values (±SD): peak pressure gradient (PPG): 18.51(±7.64) mm Hg; mean pressure gradient (MPG): 10.88(±5.62) mm Hg; peak velocity (PV): 1.97(±0.43)m/s; doppler velocity index (DVI): 0.61(±18); pulmonary velocity acceleration time (PVAT): 87.35(±15.16) ms; effective orifice area (EOA): 2.98(±1.02) cm2;and effective orifice area to body surface area ratio (EOA/ BSA): 1.81(±0.62) cm2/m2. Comparing these measurements with those obtained from the second follow-up (at week four post-op) failed to hold significant difference in all values except for PVAT, which had increased from its primary value (p�=�0.038). Also, right ventricular (RV) function showed significant improvement throughout the follow up period. CONCLUSION: The findings of this study help strengthen the previously scarce data pool and better establish the normal values for Doppler hemodynamics in mechanical pulmonary prosthesis

The Effect of Mesenchymal Stem Cells Derived-Conditioned Media in Combination with Oral Anti-Androgenic Drugs on Male Pattern Baldness: An Animal Study

Objective: Androgenetic alopecia (AGA) is a prevalent form of hair loss, mainly caused by follicular sensitivity toandrogens. Despite developing different anti-androgen treatment options, the success rate of these treatments hasbeen limited. Using animal models, this study evaluated the therapeutic effects of umbilical cord (UC) stem cellconditioned media (CM) combined with oral anti-androgens for hair regeneration.Materials and Methods: In this experimental study, Poloxamer 407 (P407) was used as a drug carrier forsubcutaneous testosterone injection. AGA models were treated with oral finasteride, oral flutamide, and CMinjections. Samples were thoroughly evaluated and compared using histological, stereological, and molecularanalyses.Results: Injecting CM-loaded hydrogel alone or combined with oral intake of anti-androgens improved hair regeneration.These treatments could promote hair growth by inducing hair follicles in the anagen stage and shortening the telogenand catagen phases. Furthermore, the combination treatment led to an upregulation of hair induction gene expressionwith a downregulation of inflammation genes.Conclusion: Through a reduction in inflammation, injection of CM-loaded hydrogel alone or combined with oral intakeof anti-androgens induces the hair cell cycle with regeneration in damaged follicles. Hence, this could be a promisingtherapeutic method for AGA patients

Data on investigating the quantitative and qualitative status of effluent in a petrochemical complex in Iran

The aim of this data was investigating the quantity and quality of the produced effluent by different petrochemical industry units in Iran and comparison of effluent with the present standards. In the present data, 5 effluent channel of the complex with interval of 12 h (in two shifts) were sampled and 28 physical and chemical parameters were analyzed according to the standard methods. These parameters are pH, Temperature, DO, Conductivity, Color, TDS, TSS, TP, PO43−, Oil, BOD5, COD, Turbidity, TKN, Fe, Ca2+, Mg2+, Cl−, SO42−, Si4+, CO32−, HCO3, NO2−, NO3−, NH3, Na, K+, Mn2+. Then, the average of each parameter was obtained for each channel, and finally, values of these parameters were compared with the standard set by Iranian Environmental Protection Agency for discharge to surface water resources. Gathered Data showed that many of these parameters, including Oil, BOD5, COD, Turbidity, PO43−, SO42−, TSS, in effluent of industrials are higher than the permitted amount. Therefore, regarding discharge of the to the surface water (seawater) and in accordance with Environment Protection Agency standards for effluent disposal, it should be purified to about 90% prior to discharge. Due to high concentration of solutes in petrochemical wastewater, it is not possible to use it for agricultural purpose. In this data, due to ethical considerations, we did not mention the name of petrochemical complex. Keywords: Wastewater, Environmental standards, Petrochemical complex, Industrial effluen

Evaluating the quality of the medium density fiberboard made from kenaf core and stalk

Utilization of kenaf core and stalk for the production of medium density fiberboard was investigated. Control boards were produced using poplar wood fibers and compared with kenaf boards. Urea formaldehyde resin was used. Medium density fiberboards were made at two densities of 0.55 and 0.75 g/cm3.  Six combinations of variable were tested and for each combination of variables, 3 replications and the total of 18 laboratory MDF boards were produced. The kenaf core and stalk fiber dimensions and the mechanical and physical properties of the MDF boards were measured. Factorial experimental design was used for statistical analysis of generated data. Results showed that average length of kenaf core and stalk fiber are 3.607 and 0.78 mm, and their respective diameters are 41.48 and 36.76 μm. The results of modulus of rupture, modulus of elasticity, internal bonding and thickness swelling after 2 and 24 hours immersion in water showed that kenaf core fiberboard with the density of 0.75 g/cm3 are above the required values for these boards which indicate that these properties are comparable with MDF from wood. It can be expressed that kenaf core fibers can substitute the poplar wood fiber for MDF production. The modulus of rupture, modulus of elasticity and internal bonding of MDF boards produced using kenaf core was improved as the density of the boards increased.  The thickness swelling after 2 and 24 hours immersion in water was comparable to poplar fiberboard. Kenaf stalk fiberboard showed lower mechanical and physical properties due to the presence of bark fibers

Investigate the effect of anionic trash management through removal and neutralization of dissolved and colloidal substances (DCS) On properties of CMP pulp and paper

During the paper manufacturing process, especially when mechanical pulp or recycled pulp used, a large amount of soluble and colloidal substances (DCS) are comprised and dispersed or dissolved in the process water. Accumulation of DCS during the papermaking operation with the increasing closure process water systems, can have a variety of deleterious effects on papermaking process and paper products. In this study, The effect of anionic trash neutraliziation was investigated by using different catcher anionic tarsh and also pulp washing (removal of anionic trash) on the CMP pulp and paper properties. After the initial preparation chemi-mechanical pulp (CMP), bleached long fiber kraft pulp and mixing the pulps with each other, filler of precipitated calcium carbonate (PCC) was added. Then a cationic retention aid That in this research has been cationic polyacrylamide were added to the mix. To neutralization of and reduce the negative effects of anionic trash, different levels of poly DADMAC with molecular weight 100000-200000 (0.025, 0.05, 0.1, 0.15%) and poly aluminium chloride (PAC) (0.1, 0.25, 0.5%) was added before adding of retention aid. Results showed that the use of different neutralizers imprived of zeta potential and drainage time of pulp, and increase of total retention; but reduces burst index of paper that was not significant statistically. CMP pulp washing and drainage treatment caused reducing COD and on the other hand reduced the amount of anionic trash with organic origin. Washing treatment pulp improved drainage time from pulp, total retention; but reduced burst index. Based on these findings, using cationic polyelectrolyte can introduce as a good strategy to reduce the harmful effects anionic trash and more retention suspension components

The Effect of Melatonin on Maturation, Glutathione Level and Expression of HMGB1 Gene in Brilliant Cresyl Blue (BCB) Stained Immature Oocyte

Objective: Nutrients and antioxidants in the medium of immature oocyte have a profound effect on maturation, fertilization and development of resulting embryos. In this study the effects of melatonin as an antioxidant agent on maturation, glutathione level and expression of high mobility group box-1 (HMGB1) gene were evaluated in immature oocytes of mice stained with brilliant cresyl blue (BCB).Materials and Methods: In this experimental study, immature oocytes were harvested from ovaries of Naval Medical Research Institute (NMRI) mice. Oocytes were stained with 26 μM BCB for 90 minutes and transferred to in vitro maturation medium containing varying doses of melatonin (10-12, 10-9, 10-6, 10-3 M) and without melatonin, for 22-24 hours. Maturation was monitored using an inverted microscope. Glutathione was assessed by monochlorobimane (MCB) staining and HMGB1 expression in mature oocyte was analyzed using real-time polymerase chain reaction (PCR).Results: Melatonin in the concentration of 10-6 M had the most effect on maturation and HMGB1 expression of BCB+ oocytes (p0.05).Conclusion: In vitro treatment with melatonin increases the maturation and HMGB1 expression in BCB+ immature oocytes and has no significant effect on glutathione levels