Calculation of the interaction between a complex turbulent shear layer and an external inviscid stream

Imperial Users onl

Student engagement in online and blended learning in a higher education institution in the Middle East: Challenges and solutions

This paper aims to identify challenges to students’ engagement in online learning at the Qatar branch campus of America’s Georgetown University, and to propose solutions. Specifically, it: 1) identifies challenges and solutions from students’ perspectives; 2) provides recommendations for developing instructional policies to maximise student engagement in synchronous learning contexts; and 3) aims to contribute to the literature on the engagement of Arabic as a Foreign Language (AFL) learners and Arabic Heritage Learners (AHLs) in online learning in higher education (HE) in the Middle East. It did so by collecting qualitative data, using an open-ended questionnaire from 13 Arabic as a Foreign Language and Arab Heritage learners. We investigate these learners’ perceptions and experiences of student engagement in online learning within the social presence dimension of the Community of Inquiry (CoI) framework. In addition to presenting a set of challenges that our students experienced in their online learning, especially under the unprecedented health, social and mental constraints created by Covid-19, we highlight their solutions to these challenges. We conclude by offering a set of recommendations that we hope AFL and Arabic Heritage (AH) programmes and institutions will find useful

Assessment of Plasma Fibrinogen Level and Lipid Profile in Sudanese Smokers

Background: Cigarette smoking is a leading preventable risk factor for the development and progression of cardiovascular diseases (CVDs). Epidemiologic studies in smokers confirm the association between the alteration in lipid profile levels and CVDs risk. Fibrinogen, an acute phase reactant with active involvement in endothelial function, thrombosis and inflammation. It is signified as a systemic marker of carotidatherosclerosis. The purpose of this study was to assess the level of fibrinogen and lipid parameters in Sudanese tobacco smokers. Methods: This case-control study included 55 adult male of a current smoking status; their ages ranged between 18 and 54 years, and 100 non-smokers considered as controls. We evaluated the effect of cigarette smoking on plasma fibrinogen and serum lipid profile. The American Heart Association guidelines and reference ranges were used to identify the smokers with increased risk of coronary heart disease. Results: Our study revealed an increase in the levels of fibrinogen, total cholesterol, and low-density lipoprotein cholesterol (LDL-C) among smokers than controls, whereas the mean level of and triglycerides did not differ. The levels of highdensity lipoprotein cholesterol HDL-C demonstrated decrement. Further, smokers were classified according to the atherogenic risk index LDL-C/HDL-C ratio, the studied parameters fibrinogen, total cholesterol, and triglycerides were significantly increased in those who have ratio 4.5 and more (p = 0.001, p = 0.018, p = 0.007, respectively). Smokers with atherogenic index ≥ 4.5 were more likely to have ≥ 300 mg/dl fibrinogen level (odds ratio (OR) 3.96, 95% confidence interval (95%CI) 1.14– 13.73, p = 0.026). Moreover, the level of the fibrinogen can be predicted by linear regression equation: Fibrinogen level = 19.49 + 79.08 (the ratio of LDL-C ⁄HDL-C), r = 0.37, p = 0.008, 95%CI 21.20–136.95. Conclusion: Increased fibrinogen, LDL-C, and LDLC/HDL-C ratio may potentiate the development of cardiovascular disease in smokers

Analytical robustness of quantitative NIR chemical imaging for Islamic paper characterization

Recently, spectral imaging techniques such as Multispectral (MSI) and Hyperspectral Imaging (HSI) have gained importance in the field of heritage conservation. This paper explores the analytical robustness of quantitative chemical imaging for Islamic paper characterization by focusing on the effect of different measurement and processing parameters, i.e. acquisition conditions and calibration on the accuracy of the collected spectral data. This will provide a better understanding of the technique that can provide a measure of change in collections through imaging. For the quantitative model, special calibration target was devised using 105 samples from a well-characterized reference Islamic paper collection. Two material properties were of interest: starch sizing and cellulose degree of polymerization (DP). Multivariate data analysis methods were used to develop discrimination and regression models which were used as an evaluation methodology for the metrology of quantitative NIR chemical imaging. Spectral data were collected using a pushbroom HSI scanner (Gilden Photonics Ltd) in the 1000-2500 nm range with a spectral resolution of 6.3 nm using a mirror scanning setup and halogen illumination. Data were acquired at different measurement conditions and acquisition parameters. Preliminary results showed the potential of the evaluation methodology to show that measurement parameters such as the use of different lenses and different scanning backgrounds may not have a great influence on the quantitative results. Moreover, the evaluation methodology allowed for the selection of the best pre-treatment method to be applied to the data. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Quantitative chemical near-infrared hyperspectral imaging of Islamic paper

Heritage objects are well known for their compositional inhomogeneity due to materials and processes used in their production. Hyperspectral imaging is gaining importance in the field of heritage conservation by expanding spectroscopy to the examination of an entire surface of an object. This paper focuses on the application of near-infrared hyperspectral imaging to the characterisation of Islamic paper using a pushbroom HSI scanner in the 1000–2500 nm range to collect hyperspectral datacubes. A calibration target was devised using 105 samples from the well-characterised reference Islamic paper collection of the UCL Institute for Sustainable Heritage. Two material properties of Islamic paper were of interest: starch sizing and degree of polymerisation (DP). In addition to the developed discrimination and regression models using multivariate data analysis methods, a quantitative chemical map of the DP of an Islamic paper was generated as a case study for improved visualisation of the inhomogeneity of material properties, of value to researchers and conservators. As a case study, this research shows the wealth of valuable chemical information that near-infrared hyperspectral imaging could provide for diverse heritage applications in the future

Role of cross-shell excitations in the reaction 54Fe(d_pol,p)55Fe

The reaction 54Fe(d_pol,p)55Fe was studied at the Munich Q3D spectrograph with a 14 MeV polarized deuteron beam. Excitation energies, angular distributions and analyzing powers were measured for 39 states up to 4.5 MeV excitation energy. Spin and parity assignments were made and spectroscopic factors deduced by comparison to DWBA calculations. The results were compared to predictions by large scale shell model calculations in the full pf-shell and it was found that reasonable agreement for energies and spectroscopic factors below 2.5 MeV could only be obtained if up to 6 particles were allowed to be excited from the f_7/2 orbital into p_3/2, f_5/2, and p_1/2 orbitals across the N=28 gap. For levels above 2.5 MeV the experimental strength distribution was found to be significantly more fragmented than predicted by the shell model calculations.Comment: 9 pages, 12 figures, 3 tables, submitted to European Physical Journal

Material properties of Islamic paper

In contrast to scientific research focussing on European paper, there is a significant gap in our knowledge of Islamic papermaking. This research surveys the evidence of techniques and materials typically used in Islamic papermaking, to deduce what might be considered as the most significant characteristics. A substantial collection of 228 Islamic papers (~18th–20th century) was characterized using chemical analytical methods: surface profilometry, gloss measurements, specular vs. diffuse reflectance ratio at 457 nm, scanning electron microscopy and infrared spectroscopy for identification of polishing, iodine test for identification of starch, Raspail test for identification of rosin, and fibre furnish analysis. Morphological analysis was performed to examine the presence of watermarks and sieve patterns. In addition, acidity and degree of polymerization of cellulose in paper were determined to explore the average material state of paper in the collection. Near infrared spectroscopic data of the collection were correlated to chemical properties with the aid of multivariate data analysis methods. Four different models were developed focusing on two main characteristics of Islamic paper: two for identification of polishing and starch, and two quantitative models to determine the acidity and degree of polymerization of cellulose in paper. While no single defining characteristic of Islamic paper was identified, 88 % of all papers in the studied collection either contain starch or are polished, or both. ~2 % of papers contain rosin. The majority of papers are neutral to mildly acidic, which is in contrast to their extensive degradation: ~69 % have DP < 1000. Polishing and starch appear to be associated with current values of pH and DP. The developed non-destructive characterization methodology could be applied to Islamic collections in libraries and archives to expand the database with the material properties of papers of known age and provenance and thus better understand geographic and temporal distributions of papermaking practices in Islamic countries

HPLC-DAD stability indicating determination of nizatidine in bulk and capsules dosage form

AbstractThis work describes the stability-indicating determination of the H2-receptor antagonist nizatidine in its bulk and capsules dosage form using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). The developed method involved the use of Thermo Hypersil BDS-C8 (4.6×250mm, 5μm particle size) column and a mobile phase composed of 0.05M phosphoric acid and acetonitrile (50:50, v/v). The mobile phase was pumped at a flow rate of 1mL/min. Quantification of nizatidine was based on measuring its peak area at 320nm. The retention time for nizatidine was about 3.61min. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curve of nizatidine was linear in the range of 5–50μg/mL with correlation coefficient >0.9999. The drug was subjected to forced-degradation conditions of acidic and basic hydrolysis, oxidation, dry heat and UV photolysis where it showed considerable degradation in basic and oxidative conditions. The proposed method proved to be specific and stability-indicating by resolution of the drug from its forced-degradation products. The validated HPLC method was applied to the analysis of nizatidine in capsules dosage form where it was quantified with recoveries not less than 98.2%. Assay results were statistically compared to USP 2011 pharmacopeial method where no significant difference was observed between the proposed and reference methods

Q-Value for the Fermi Beta-Decay of 46V

By comparing the Q-values for the 46Ti(3He,t)46V and 47Ti(3He,t)47}V reactions to the isobaric analog states the Q-value for the superallowed Fermi-decay of 46V has been determined as Q_{EC}(46V)=(7052.11+/-0.27) keV. The result is compatible with the values from two recent direct mass measurements but is at variance with the previously most precise reaction Q-value. As additional input quantity we have determined the neutron separation energy S_n(47Ti)=(8880.51+/-0.25) keV