Velocity Profiles for Flow of Omani Crude Oils and Other Liquids

Velocity profiles of Newtonian immiscible liquids undergoing laminar flow between two horizontal plates under pressure gradient are investigated using a momentum balance equation. The differential equation describing the flow has been solved and equations for the velocity profiles of a two-layer and three-layer liquid systems are presented. As examples, we show flow patterns of two-layer water-crude oil system and three-layer system involving water, tetrachloromethane, xylene, cyclopentane and hexane. A distinctive pattern is noticeable between the velocity profiles of heavy (API 19.19) and light (API 40.89) Omani crude oils

HEAVY METAL TOXICITY IN FISHES OF POLLUTED LAKES OF DHAKA CITYAND ITS IMPACTS ON HUMAN HEALTH

The City of Dhaka is not built up plan wise from the beginning yet till date. The land uses are not following the urbanization rules correctly. Due to the laggings of proper water and air flow and basic treatment of household and industrial utilizing water, some of the major health issues are concerned. This research works is on the focus of heavy metal contamination in fishes of two major lakes in Dhaka city called Dhanmondi Lake and Gulshan Lake. The research is focusing mainly the study on Cr, Cd and Pb concentration in fishes along with other elements. Concentration of Cr is found in ranges of 3.45 μg/gm – 10.25 μg/gm, Cd is 2.17 μg/gm – 9.78 μg/gm and Pb is 1.132 – 7.102 μg/gm. The major element K and Ca with other trace elements are also projected. The data acquisition setup is calibrated using 2.2 MeV proton beam in the current ranges of 5nA to 15nA. The Van-de Graff Accelerator of Atomic Energy Centre, Dhaka has been used for sample irradiation. The IBA technique Proton Induced X-ray Emission (PIXE) has been applied using Si(Li) detector (SL30165) and other ORTEC nuclear electronics. The calibration and standardization of PIXE setup has been done using X-ray source, and IAEA standard CuSx (thin), Soil-7 (thick)

Bone Morphogenic Protein Is a Viable Adjunct for Fusion in Minimally Invasive Transforaminal Lumbar Interbody Fusion

Study DesignComparison of prospectively collected data of patients undergoing minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) with and without recombinant human bone morphogenic protein 2 (BMP).PurposeTo compare the clinical, radiological outcome and complications of patients undergoing MIS-TLIF with and without BMP.Overview of LiteratureBMP is an effective fusion enhancer with potential complications. Direct comparison of MIS-TLIF with and without BMP is limited to retrospective studies with short follow-up.MethodsFrom June 2005 to February 2011, consecutive cases of MIS-TLIF performed by a single surgeon were included. North American Spine Society (NASS) score, Oswestry disability index (ODI), Short Form-36 (SF-36), and visual analogue score (VAS) were assessed preoperatively and at 6 and 24 months postoperatively. Fusion rates and complications were noted.ResultsThe 252 cases comprised 104 non-BMP and 148 BMP cases. The BMP group was significantly older (mean age, 60.2 vs. 53.9; p<0.01). Preoperative scores were similar. Immediate postoperative morphine usage was significantly lower in the BMP group (12.4 mg vs. 20.1 mg, p<0.01). At 6 months, the BMP group had lower VAS back and leg pain scores (p<0.01). At 2 years, the BMP group had better leg pain scores (p<0.01), ODI (15.4 vs. 20.3, p=0.04) and NASS scores (8.8 vs. 15.8, p<0.01). Both groups showed significant clinical improvement compared to their preoperative levels. The BMP group attained a significantly higher rate of fusion at 6 months follow-up (88.4% vs. 76.8%, p=0.016) with no difference at 2 years. The non-BMP and BMP group had 12 (11.5%) and 9 (6.1%) complications and 5 (4.8%) and 2 (1.4%) reoperations, respectively.ConclusionsThe use of BMP to augment fusion in MIS-TLIF is an acceptable alternative that has potential benefits of less pain in early and intermediate postoperative follow-up

Delamination of pipeline steels: determination of an anisotropic cleavage criterion

Cette étude concerne l’effet de l’anisotropie de la rupture par clivage appliquée à deux tôles d’acier faiblement allié, ferrito-bainitiques, pour gazoducs. La rupture de la tôle par délaminage est étudiée en fonction de la microstructure et du chargement mécanique, afin d’optimiser les propriétés de ces aciers et notamment leur résilience mesurée par essais Battelle et Charpy. Des essais mécaniques ont été effectués sur des mini-éprouvettes axisymétriques entaillées, dimensionnées à cette intention et prélevées dans les directions principales de la tôle, y compris dans la direction travers court. Des essais de traction ont permis de tracer une courbe de transition ductile-fragile sur ces éprouvettes entaillées, dans une gamme de températures comprise entre +20°C et -140°C. Les mécanismes de rupture et les sites d’amorçage de la rupture par clivage ont été identifiés au microscope électronique à balayage. L’analyse mécanique de ces essais a été menée aux différentes températures, le comportement mécanique étant identifié sur éprouvettes lisses sollicitées dans les mêmes directions que les éprouvettes entaillées. Des simulations par éléments finis des essais sur éprouvettes entaillées ont été effectuées afin d’analyser les champs de contrainte et de déformation à rupture et d’en extraire une valeur de contrainte critique de clivage, en fonction de la direction de sollicitation. L’impact du modèle de comportement choisi (critère de plasticité isotrope ou non) sur la valeur de la contrainte critique de clivage a été évalué. Le critère de rupture proposé tient compte des paramètres microstructuraux des aciers étudiés

Temperature stable mid-infrared GaInAsSb/GaSb Vertical Cavity Surface Emitting Lasers (VCSELs)

GaInAsSb/GaSb based quantum well vertical cavity surface emitting lasers (VCSELs) operating in mid-infrared spectral range between 2 and 3 micrometres are of great importance for low cost gas monitoring applications. This paper discusses the efficiency and temperature sensitivity of the VCSELs emitting at 2.6 μm and the processes that must be controlled to provide temperature stable operation. We show that non-radiative Auger recombination dominates the threshold current and limits the device performance at room temperature. Critically, we demonstrate that the combined influence of non-radiative recombination and gain peak – cavity mode de-tuning determines the overall temperature sensitivity of the VCSELs. The results show that improved temperature stable operation around room temperature can only be achieved with a larger gain peak – cavity mode de-tuning, offsetting the significant effect of increasing non-radiative recombination with increasing temperature, a physical effect which must be accounted for in mid-infrared VCSEL design

Velocity Profiles for Flow of Omani Crude Oils and Other Liquids

Velocity profiles of Newtonian immiscible liquids undergoing laminar flow between two horizontal plates under pressure gradient are investigated using a momentum balance equation. The differential equation describing the flow has been solved and equations for the velocity profiles of a two-layer and three-layer liquid systems are presented. As examples, we show flow patterns of two-layer water-crude oil system and three-layer system involving water, tetrachloromethane, xylene, cyclopentane and hexane. A distinctive pattern is noticeable between the velocity profiles of heavy (API 19.19) and light (API 40.89) Omani crude oils