In-Situ Synthesis of Aluminum- Titanium Diboride Metal Matrix Hybrid Nanocomposite

Metal matrix nanocomposites (MMNC’s) are reported to have improved mechanical, thermal and electrical properties as compared to their respective base alloys. To date, these materials have been synthesized mainly by powder metallurgy or deformation processing. Solidification synthesis of MMNCs is a promising method, capable of economically producing large and complex shapes, however technical challenges including nanoparticle agglomeration, and poor interfacial strength have hindered the adoption of this technology. In-situ processing methods, in which the reinforcements are synthesized in liquid metals, typically via exothermic reactions offer the potential for improved dispersion and interfacial bonding between the reinforcement and the matrix, however this technique has been largely unexplored in the literature for metal matrix nanocomposites. The objectives of this research were to examine the feasibility of synthesizing nano or sub-micron size particulates in liquid aluminum using in-situ stir mixing and squeeze casting. An exothermic reaction was designed to synthesize Al2O3 and TiB2 from TiO2 particles and elemental boron in an aluminum melt. This dissertation investigates (i) the mechanism of aluminothermic and borothermic reduction of titanium oxide in the presence of molten aluminum and boron, (ii) in situ synthesis of micron and nano sized particles via solidification processing, and (iii) the effects of processing variables on the physical, microstructural, mechanical and tribological properties of in-situ MMNCs. Microstructural examination and theoretical analysis indicates that the reaction to form TiB2 and Al2O3 proceeds through several complex non-equilibrium reactions. A multi-stage reaction model is proposed to describe the process by which the TiO2 surface is reduced to form Al2O3 and TiB2. The effects of the powder particle size on the formation of reinforcing phases and microstructural evolution have been investigated and it was found that nanosized TiO2 powder promoted the formation of smaller size reinforcing phases. Furthermore, a solidification route has been designed to fabricate in-situ aluminum composites reinforced with submicron Al2O3 and TiB2 particulates. Experimental and theoretical analysis is presented that shows that the particle size and refining power of nanoparticles is controlled by the viscosity of the melt, rather than precipitation and growth. In addition, it was found that increasing the weight percentage of nanoparticles of TiO2 resulted in an increase in elastic modulus with good agreement to analytical models. Increasing the weight percentage of reinforcement up to 4 wt% resulted in an increase in the hardness greater than that predicted by the rule of mixtures or the Hall Petch relationship

Multiwell injectivity for storage of CO2 in aquifers

AbstractGeological storage of CO2 in deep saline aquifers has been suggested as a potential methodology for reducing CO2 e missions over short to medium terms. A number of projects are in operation and a larger number are being designed. However, not all aquifers are equally suitable for CO2 storage. Virtually all publications that present the criteria for selection of suitable sites for geological storage of CO2 in aquifers, consider injectivity to be among the top three criteria, with capacity and containment being the other two. Among parameters that affect injectivity, permeability can vary by the largest degree. Unfortunately, selection of storage sites with sufficient permeability that would enable injection of the desired volumes, using only one injection well–such as that achieved in Sleipner–is not always possible. When this is not possible, injectivity needs to be improved for example by increasing the contact area with the formation (e.g. through application of hydraulic fracturing or horizontal wells) and/or employing more than one injector. Recent studies indicate that multiwell injectivity does not increase linearly with the number of injectors. Instead, progressively more number of wells is required to achieve an equal increment in injection rate.It is well known, that because of the small compressibility of the water, it takes a short time for the pressure pulse from the different injectors to cause significant interference. We use this observation and suggest a well pattern that would minimize such interference effects in an open and homogeneous aquifer. Next, we develop an analytical solution, for the injectivity of multiwell systems as a function of (i) number of wells, (ii) distance between wells, and (iii) injectivity of one wel.. The analytical solution obtained for single-phase flow is applied to cases of CO2 injection in aquifers. Numerical experimentation over a wide range of parameters demonstrates the applicability of the analytical solution for two-phase flow problems.This relation is developed for homogeneous aquifers; suggesting that such a relationship may be used for scoping and screening studies early on when data us scarce, and the effect of the number of wells and/or their distance on overall injectivity is being studied. Furthermore, such a relationship allows examining the economic balance between increasing the number of wells or the distance among wells

Visual Disturbance in a Patient with Amiodarone Treatment Following Refractive Surgery

Amiodarone is an antiarrhythmic medication used to treat a number of irregular heartbeats. Known ocular side effects of amiodarone include visual loss, swelling of the optic disc without visual deterioration and abnormal blue color vision. After discontinuation of amiodarone either a visual improvement or a permeant deterioration may result. Here we report a rare case of visual disturbance in a patient with a history of amiodarone treatment complaining from seeing colored rings around the lights after refractive surgery. After the discontinuation of amiodarone treatment the patient complains subsided. Keywords: Amiodarone; Visual side effect; Treatment; Refractive surgery

The effect of Nano-MgO on the mechanical and flammability properties of hybrid nano composites from wood flour-polyethylene

This study considered the effect of nanomagnesium oxide on the mechanical and flammability features of composites made of wood flour and high-density polyethylene. A sample of wood flour was made from the mixture of hardwoods and high density polyethylene with the weight ratio of 50%. Maleic anhydride was added as a compatibilizer (2 phc), and nanomagnesium oxide was applied at 6 levels (0, 1, 2, 3, 4, 5 phc). These materials were mixed, and samples were prepared with determined sizes by injection molding machine. The samples were subjected to flexural tests to examine the mechanical features, and to study flammability strength, various tests were conducted with a cone calorimeter, including the amount of char residue, total smoke production, time to ignition, and heat release rate, according to ASTM E1354-92 (1992). The addition of up to 3 phc nanomagnesium oxide increased flexural strength and modulus, but further additions decreased these values. The addition of 5 phc nanomagnesium oxide increased the char residue and ignition time, and it decreased the heat release rate, total smoke production, and burning rate. Scanning electron microscopy and energy dispersive X-ray (EDX) analysis indicated the improper transmittance of nanomagnesium oxide and accumulations in the samples.   PDF XM

Canadian Experiment for Soil Moisture in 2010 (CanEX-SM10): Overview and Preliminary Results

The Canadian Experiment for Soil Moisture in 2010 (CanEx-SM10) was carried out in Saskatchewan, Canada from 31 May to 16 June, 2010. Its main objective was to contribute to Soil Moisture and Ocean salinity (SMOS) mission validation and the pre-launch assessment of Soil Moisture and Active and Passive (SMAP) mission. During CanEx-SM10, SMOS data as well as other passive and active microwave measurements were collected by both airborne and satellite platforms. Ground-based measurements of soil (moisture, temperature, roughness, bulk density) and vegetation characteristics (Leaf Area Index, biomass, vegetation height) were conducted close in time to the airborne and satellite acquisitions. Besides, two ground-based in situ networks provided continuous measurements of meteorological conditions and soil moisture and soil temperature profiles. Two sites, each covering 33 km x 71 km (about two SMOS pixels) were selected in agricultural and boreal forested areas in order to provide contrasting soil and vegetation conditions. This paper describes the measurement strategy, provides an overview of the data sets and presents preliminary results. Over the agricultural area, the airborne L-band brightness temperatures matched up well with the SMOS data. The Radio frequency interference (RFI) observed in both SMOS and the airborne L-band radiometer data exhibited spatial and temporal variability and polarization dependency. The temporal evolution of SMOS soil moisture product matched that observed with the ground data, but the absolute soil moisture estimates did not meet the accuracy requirements (0.04 m3/m3) of the SMOS mission. AMSR-E soil moisture estimates are more closely correlated with measured soil moisture

Comparing the effect of low-power laser therapy with methylprednisolone injection in unilateral plantar fasciitis

Background: Plantar fasciitis accounts for 11 to 15 percent of foot pain in adults. Although an injection of corticosteroids is a common treatment in plantar fasciitis, it has side effects and short-term pain relief. Therefore, this study aimed to compare the effect of low-power laser therapy (LPLT) with methylprednisolone injection in unilateral plantar fasciitis patients.Materials and Methods: In this clinical trial study, 40 patients with unilateral plantar fasciitis were randomly allocated into two groups (n=20). In the first group, 40 mg of prednisolone was locally injected and the second group received LPLT in 10 sessions. Levels of pain and morning stiffness were evaluated.Results: Forty-two percent of cases were male and 57.5 female. Fifty-five percent of the patients had right and 45 had left foot fasciitis. The mean age of the patients was 52.98 years and the disease duration was 32.38 weeks. In men pain was seen more in the right foot and in women in left foot. Duration of pain in women with plantar fasciitis was more than the men. The effect of the two therapies on morning stiffness and pain reduction was the same in both groups. Moreover, pain reduction measured by visual analogue scale had a similar effect during the study in both groups. Conclusion: LPLT like corticosteroid injection has significant effect on the intensity and duration of pain and morning stiffness in plantar fasciitis and can be used as an alternative to corticosteroid injection

The effects of ATO on mitochondria apoptosis pathway genes expression in APL cell line

Abstract Purpose and Background: Acute promyelocystic leukemia is the most malignant acute leukemia that leads to death in few weeks. It constitutes 10-15% of acute myelocystic leukemia. Arsenic trioxide, as a single agent factor, is known as the best treatment for acute promyelocystic leukemia, which mainly functions by inducing apoptosis. However, there is no clear image of the mechanism through which apoptosis is induced and how the genes expression is deeply affected. Thus, the present study is an attempt to examine the effect of the agent on expression of the genes dealing with the cancer. Methodology: The study was carried out as an analytical work. To find out about the mechanisms effective on inducing apoptosis, cell line NB4 were cultured with 0.5µM, 1 µM, and 2 µM arsenic trioxide and their RNA was extracted after 12hrs, 24hrs, 28hrs, and 72hrs. Following cDNA synthesis, apoptosis genes expression at mitochondria pathway including caspase 3, Mcl-1, and Bcl-2 were examined using Real-Time PCR. The data was analyzed using t-test and variance analysis in Excel. Findings: It was found that arsenic caused apoptosis was featured with decrease of mRNA expression of Bcl-2 anti-apoptotic. However, expression of caspase 3 and Mcl-1 genes remained unchanged after culturing by arsenic. Conclusion: The results showed that changes in Bcl-2 gene expression can be considered as a mechanism of apoptosis caused by arsenic, while caspase 3 and Mcl-1 genes had no effect on the mechanism

Knowledge, attitudes and practices of cleaning staff regarding hepatitis B virus

 Abstract Background: Hepatitis B virus (HBV) is endemic in human population. It is estimated that 400 million people are infected with HBV in the world. Healthcare workers face with the risk of HBV infection during their work. Despite the increase of the disease, lack of knowledge regarding the mode of transmission and methods of prevention including immunization is still a threat. Purpose: The aim of this descriptive study was to assess knowledge, attitudes and practice of cleaning staff at Labafinejad Hospital regarding prevention of HBV.  Methods:  A questionnaire and a checklist of observation were used for data collection. The questionnaire consisted of 4 parts: 1) 18 questions regarding demographic characteristics; 2) 32 questions on knowledge, route of transmission and prevention of HBV infection; 3) 18 questions on attitude and 4) 4 questions regarding practice. It was validated and made reliable by content and test-retest methods (r=0.87). The questionnaire was distributed among 100 cleaning staff.   Results: Finding showed that 75% of samples was male and 25% female. Knowledge score on universal precautions was moderate, attitude was good and practice was moderate. The results also showed that their attitude and practice were significantly correlated (P=0.009), practice had a significant correlation with age and sex (P=0.03). However, Furthermore, there was a significant correlation between knowledge with attitude, (P=0.35) and knowledge with practice (P=0.12). Conclusion: It can be concluded that cleaners had positive attitude toward HBV and implementation of universal precautions. On the other hand, cleaners had moderate knowledge and practice with regard to the mode of transmission. Therefore, performing comprehensive educational programs for cleaning staff regarding universal precautions seems necessary. Key words: HBV, Knowledge, Attitude, Practice

Effect of electromagnetic field on okra (Hibiscus sculentus L.) developmental stages and the effect of okra extract on breast cancer cells

Background and objectives: Electric, magnetic and electromagnetic fields can act as stress factors with different effects on biological systems. Due to the nutritional and medicinal values, and the increasing electromagnetic radiations, the present study was performed to investigate the effects of the electromagnetic field on the developmental stages and cytotoxic properties of okra. Methods: Both dry and wet seeds were exposed to electromagnetic field with the intensities of 2 and 4 mT for 60 minutes. MTT assay was applied to evaluate the potential cytotoxic effects of okra extract on MCF-7 cell line. The anatomical structure of leaves in both treated and untreated (control) plants were examined. Results: The results showed that a field intensity of 4 mT increased the speed of germination of wet treated seeds and the stem length of dry treated seeds. MTT assay revealed no cytotoxicity of the aqueous extracts of okra pods up to the concentration of 100 μg/mL from either the treated or the control plants towards the MCF-7 cell line. Conclusion: The results suggest that the electromagnetic fields would be able to increase the speed of germination without effects on percentage of germination