Quantitative and Qualitative Evaluation of Various Positive-Displacement Compressor Modeling Platforms

Several regulatory measures aimed to mitigate climate change are forcing compressor manufacturers to replace current refrigerants to those with low Global Warming Potential (GWP). New refrigerants need to be evaluated to ensure adequate efficiency for use in modern products. Evaluation can be done heuristically, which is expensive and timeconsuming, while a carefully designed simulation model can provide similar outcomes for a significantly reduced cost. This paper presents a comparison between various userdeveloped and existing reciprocating compressor models to assist in the selection of a suitable modeling platform for a wideranging study. The reciprocating compressor is selected because of the simplicity of the model to ensure consistency across different platforms. The userdeveloped models are developed in MATLAB™ and Modelica™ for the reciprocating compressor. The same compressor is also modeled using existing compressor modeling platforms, PDSim and GTSuite™. The compressor model includes three main components; geometry, compression process and frictional losses. Other submodels, like valve model and heat transfer model, are also part of the compression process. These platforms are evaluated based on both quantitative and qualitative criteria. Modelica™ is found to be computationally efficient while GTSuite™ took maximum time for simulation among the compared platforms. On a qualitative basis, PDSim is potentially a better platform for compressor optimization; which is also readily available to end user due to its opensource nature and prospects for future model development

Spontaneous Lung Herniation Leading to Extensive Subcutaneous Emphysema, Pneumothorax, Pneumomediastinum, and Pneumopericardium.

Spontaneous lung herniation is a rare phenomenon in which the lung parenchyma along with the pleural membranes protrudes outside their usual boundaries and can lead to a wide variety of complications. We are reporting a case of a middle-aged male who presented with chronic obstructive pulmonary disease (COPD) exacerbation with severe bouts of cough. Initial computed tomography (CT) chest was unrevealing, but two days later, he developed spontaneous lung herniation, which was initially managed conservatively, but later it progressed to pneumothorax, pneumomediastinum, with striking CT scan images showing extensive subcutaneous emphysema. Blowhole incisions were done on the anterior chest wall which led to ultimate recovery

Assessing Qatar’s Readiness and Potential for the Development of a Knowledge Based Economy: An Empirical Analysis of its Policies, Progress and Perceptions

Post-industrial societies are distinguished by the development of knowledge and its use both as an economic commodity and as a means to create new technologies in order to attain and maintain a competitive edge. With the support of economic strength, effective institutions that include labour, product, and capital markets, and human capital, developed industrial nations have transformed their economies into knowledge-based economies (KBEs) through the allocation of funds for research and development (R&D), innovation, and technological development. The open nature of these economies with enhanced competition policies has also contributed to the development of a KBE in these particular countries. Qatar, as one of the oil-rich countries in the Gulf Cooperation Council (GCC), has been focusing on strategies to diversify its economy beyond its traditional emphasis on oil and gas. Although these sources of revenue have been instrumental in the unprecedented success of the Qatari economy, even to the extent of avoiding the notion of the ‘resource curse’, the sustainability of generating wealth via alternative methods remains a challenge for Qatar and other similar countries. Indeed, the development of a KBE is perceived as such an alternative for Qatar; for which the country has initiated a number of strategies among its economic, financial, education, and regulatory sectors. This study, thus, aims to explore the notion transforming Qatar into a KBE as a means to enhance economic diversity, thereby investigating the nature of, and developments in, the macro and micro business environments of the country and its economy. The policies of the Qatari government are also similarly explored, so as to identify Qatar’s readiness to become a KBE. Further, this study aims to gauge the perceptions of Qatari university students towards the idea of a KBE, detailing their awareness of the Qatari government’s policies for such an economy and their expectations for the future of Qatar. To fulfill the research aims and objectives of this project, a quantitative research method is predominantly employed to analyse the primary data. Initially, the World Bank’s specialist Knowledge Assessment Methodology, or KAM, will be used in relation to secondary data, so as to assess Qatar’s readiness for becoming a KBE in comparison to other potential economic competitors. Despite the demonstration of Qatar’s strength arising from its economic variables, the KAM results show that when compared to other countries, Qatar faces certain challenges, including in the areas of innovation and human resources. Although the recent institutional changes have been encouraging, additional policies should be developed to reiterate these efforts. Correspondingly, developments related to education and training should also be continued in order to support this transformation into a KBE. The research was further expanded to investigate the opinions of Qataris with regard to Qatar’s need for a KBE and its readiness for this transformation; an enquiry was similarly made into these individuals’ understanding of ‘knowledge’, the concept of a KBE, and into their own efforts towards this transition. To this end, a questionnaire survey was conducted in order to gather primary data from university students; the results indicate that their awareness and attempts to develop themselves are rather limited. Further, the results illustrate that this demographic group is not absolutely convinced by the positive impact of Qatarisation, even though most of the students questioned thought that Qatar should adopt a KBE. And yet these same students’ knowledge of Qatar’s policies for the creation of a KBE was limited. Qatar’s policies for diversifying its economy should ultimately be perceived as a step in the right direction; the transition to a KBE, however, still requires further strategic planning and the bold implementation of these strategies. The economic strength of the country is considered to be a foundation on which such an aforementioned future can be built, notwithstanding the obstacles posed by human resources at present, especially when given the lack of trust displayed for the policy of Qatarisation by the participants of the questionnaire. The shortcomings in institutionalisation in the economy should also be considered as an important obstacle

Engine performance and exhaust emission of diesel dual fuel engine fuelled by biodiesel, diesel and natural gas

The performance and exhaust emission of 6 cylinder four stroke direct injection diesel dual fuel (DDF) engine were investigated, the duel fuel used is corn oil methyl esters consist of 5%, 10%, 15% and 20% blends with diesel and compressed natural gas (CNG). Experiment was conducted at a fixed compression ratio of 17.5:1 with variance of engine speed 1400, 1800, 2400 and 2600 rpm. Combination of Biodiesel and CNG showed a better result on engine performance in terms of horse power and engine torque compared to other types of tested fuel. The substantial decrease of 25.6 % in exhaust emission flue was observed, giving lower value of UHC and nitrogen oxide (NOx). However, when the fuel is blended with CNG, a poor performance on exhaust emission was recorded, which include carbon dioxide (CO2), carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NOx) due to presence of CNG in fuel

Unveiling Long-Lived Hot-Electron Dynamics via Hyperbolic Meta-antennas

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ANTIPROLIFERATIVE AND ANTIOXIDANT ACTIVITY OF LEAVES EXTRACTS OF MORINGA OLEIFERA

Objective: The aim of the study was to investigate the ethanolic and aqueous extract of leaves of Moringa oleifera for phytochemical constituents, antiproliferative and antioxidant activity.Methods: The ethanolic extract of leaves of Moringa oleifera, belonging to the family Moringaceae was prepared by using soxhlet apparatus and aqueous extract was prepared by using maceration process. The extract was evaluated for its phytochemical constituents. The antiproliferative effects of both extracts were checked by using MTT ([3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide]) assay on HT-29 colon cell line and the antioxidant activity were checked by using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. In antiproliferative and antioxidant activity the 5-FU (5-fluro uracil) and Ascorbic acid used as a standard drug for present results conclusion respectively.Results: The results obtained in MTT assay shown that ethanolic extract of Moringa oleifera had a more potent antiproliferative effect (growth inhibition of 62.25% at 100 μg/ml) on HT-29 colon cell line as compared to aqueous extract (% growth inhibition of 27.86 at 100 μg/ml) of Moringa oleifera. The ethanolic extract of Moringa oleifera shown more potent antioxidant activity (% inhibition of ethanolic 75.57 at 100 μg/ml) than aqueous extract (38.16 at 100 μg/ml) of Moringa oleifera. The activity shown by the extract is concentration dependent.Conclusion: In the present study we have investigated that the effect of ethanolic and aqueous leaves extracts of Moringa oleifera possess antiproliferative and antioxidant properties

Detection of Inositol Polyphosphates by Polyacrylamide Gel Electrophoresis (PAGE) under Apoptotic Conditions in Cultured SW480 Cells

Inositol phosphates are naturally occurring compounds that regulate diverse cellular processes including apoptosis. Apoptosis is a mechanism by which cells undergo natural death to maintain cellular homeostasis. It causes cell death in areas during a state that is harmful to the body. It also regulates cellular development. Previous work has shown that exogenously administered, as well as endogenously manipulated inositol phosphates bring about apoptotic changes. It has been demonstrated that cellular levels of inositol phosphates, particularly higher inositol phosphates such as inositol hexakis-phosphate (IP6) and diphosphoinositol pentakis-phosphate (IP7) levels increase during apoptotic conditions. In this study, we have attempted to separate and identify higher inositol phosphates such as IP6 by polyacrylamide gel electrophoresis (PAGE) and shown that changes in inositol phosphate levels can be detected by this method. Cells were treated with etoposide to induce apoptosis, and apoptotic cells were observed under UV light following ethidium bromide/acridine orange staining. This staining showed that IP3 - IP6 induced apoptosis in SW480 cells with IP6 being the most effective inducing agent. The extracts from apoptotic and control cells were then loaded onto the polyacrylamide gel and run along with standard IP6. Results showed that IP6 could be detected using the PAGE method and that cellular levels of IP6 were increased in SW480 cells, in which apoptosis had been induced by etoposide. Our results demonstrated that this technique could be utilized instead of the laborious radioactive labeling and HPLC separation method to study the changes in cellular levels of inositol phosphates particularly IP6

Bifunctional eff ect of fucoidan from Padina tetrastromatica against human pathogenic microbes and free radicals

The antibacterial and antioxidant effect of fucoidan fractions isolated from brown algae Padina tetrastromatica was evaluated. Even though the polysaccharide was found to be a fucan, the composition of this polysaccharide is different from those reported, and the antibacterial and antioxidant effect has not been reported so far. Three fractions (F1, F2, and F3) were isolated by anion-exchange column chromatography. Chemical analysis suggested that the polysaccharide fractions contained a significant amount of sulfate and fucose, galactose xylose, andmannose as the major neutral sugars. Antibacterial activity was checked by disk diffusion method. Antioxidant activity was investigated by various in vitro systems, including 1,1-diphenyl-2-picrylhydrazyl radical scavenging,lipid peroxide inhibition, superoxide and hydroxyl radical scavenging activity, chelating ability and reducingpower. Antibacterial and antioxidant assays suggested that the polysaccharide fraction F3 possessed goodantibacterial activity and had stronger antioxidant properties than F1 and F2. Available data obtained by in vitromodels suggested that the correlation between the sulfate content and pharmacological effect was positive.Fucoidan from P. tetrastromatica have the potential to be developed as anantibacterial and antioxidant agent, butfurther in vivo research for their mode of action are still needed to shed light on the effects. Overall, the presentexperiments showed fucoidan from marine brown algae as a potential therapeutic agent