Unicellular unsteady Rayleigh�Bénard convection in Newtonian liquids and Newtonian nanoliquids occupying enclosures: New findings

Rayleigh�Bénard convection in Newtonian liquids and Newtonian nanoliquids occupying rectangular, square and slender vertical enclosures is studied analytically in the paper using Buongiorno model with supplementary information on thermophysical properties of nanoliquids provided by phenomenological laws and mixture theory. The five-mode Lorenz model is derived under the assumptions of Boussinesq approximation, small-scale convective motions and some slip mechanisms like Brownian diffusion and thermophoresis. Inertia, Magnus effects, liquid drainage, diffusophoresis and gravity settling are neglected. Using multiscale method the analytically intractable Lorenz model of the problem is converted to a tractable Ginzburg�Landau equation the solution of which helps in quantifying the unsteady heat transport. The Ginzburg�Landau model derived directly from the governing equation is shown to be the same as that obtained via the Lorenz model. This point to the equivalence of the two models. Enhancement of heat transport due to the presence of nanoparticles is also clearly explained. Results on nanoliquids are discussed against the backdrop of Newtonian liquids without nanoparticles. Physical explanation is provided for all parameters� effects on onset and heat transport. The results pertaining to single-phase model are recovered as a limiting case of the present study. © 201

A Review on Professional Indemnity Insurance for Quantity Surveyors

Professional Indemnity Insurance is a risk shifting mechanism popular among the service providers including the delivery of construction related services. One of the guiding principles used for structuring an insurance policy is to ensure adequate indemnity. This research is to appraise various dimensions of Professional Indemnity Insurance (PII) related to the quantity surveying profession with particular emphasis on the Sri Lankan context. A comprehensive literature survey was carried out to recognize the liabilities that inspire policy requirements. A desk review was carried out to identify the deficiencies of the existing PII policies. 15 individual practitioners selected purposively were interviewed to gauge their perception and experience. All responses were considered valid for analysis. A discourse analysis was carried out to understand the themes and patterns in the context under study and draw conclusions. It was found that PII for the QS profession is at its embryonic stage. The study suggests that the uptake of enhanced policies would indeed help in fostering a fully-fledged insurance mechanism for quantity surveyors that is capable of accommodating the rapidly changing and newly added dimensions in the quantity surveying profession. Keywords: Professional indemnity insurance, Quantity surveyor, Professional liabilities, Insurance polic

Removal of Congo Red from Aqueous Solution by Waste Banana Pith

The ability of waste banana pith to remove Congo red from aqueous solution was investigated. Various parameters such as initial dye concentration, contact time, adsorbent dosage and pH effect were studied. The adsorption rate constant was found to be 1 X 10.1 min'} at 50 mg I-I dye concentration. Above 92% removal was observed in the pH range 2-11. The removal of dye by banana pith is mostly due to chemisorption

Phase Stability and Thermoelectric Properties of the Mineral FeS2: An Ab Initio Study

First principles calculations were carried out to study the phase stability and thermoelectric properties of the naturally occurring marcasite phase of FeS$_2$ at ambient condition as well as under pressure. Two distinct density functional approaches has been used to investigate the above mentioned properties. The plane wave pseudopotential approach was used to study the phase stability and structural, elastic, and vibrational properties. The full potential linear augment plane wave method has been used to study the electronic structure and thermoelectric properties. From the total energy calculations, it is clearly seen that marcasite FeS$_2$ is stable at ambient conditions, and it undergoes a first order phase transition to pyrite FeS$_2$ at around 3.7 GPa with a volume collapse of about 3$\%$. The calculated ground state properties such as lattice parameters, bond lengths and bulk modulus of marcasite FeS$_2$ agree quite well with the experiment. Apart from the above studies, phonon dispersion curves unambiguously indicate that marcasite phase is stable under ambient conditions. Further, we do not observe any phonon softening across the marcasite to pyrite transition and the possible reason driving the transition is also analyzed in the present study, which has not been attempted earlier. In addition, we have also calculated the electronic structure and thermoelectric properties of the both marcasite and pyrite FeS$_2$. We find a high thermopower for both the phases, especially with p-type doping, which enables us to predict that FeS$_2$ might find promising applications as good thermoelectric materials.Comment: 10 Figure

Effect of trigonometric sine, square and triangular wavetype time-periodic gravity-aligned oscillations on Rayleigh– Be´nard convection in Newtonian liquids and Newtonian nanoliquids

Abstract The influence of trigonometric sine, square and triangular wave-types of time-periodic gravity-aligned oscillations on Rayleigh–Be´nard convection in Newtonian liquids and in Newtonian nanoliquids is studied in the paper using the generalized Buongiorno two-phase model. The five-mode Lorenz model is derived under the assumptions of Boussinesq approximation, small-scale convective motion and some slip mechanisms. Using the method of multiscales, the Lorenz model is transformed to a Ginzburg–Landau equation the solution of which helps in quantifying the heat transport through the Nusselt number. Enhancement of heat transport in Newtonian liquids due to the presence of nanoparticles/nanotubes is clearly explained. The study reveals that all the three wave types of gravity modulation delay the onset of convection and thereby to a diminishment of heat transport. It is also found that in the case of trigonometric sine type of gravity modulation heat transport is intermediate to that of the cases of triangular and square types. The paper is the first such work that attempts to theoretically explain the effect of three different wave-types of gravity modulation on onset of convection and heat transport in the presence/absence of nanoparticles/nanotubes. Comparing the heat transport by the single-phase and by the generalized two-phase models, the conclusion is that the single-phase model under-predicts heat transport in nanoliquids irrespective of the type of gravity modulation being effected on the system. The results of the present study reiterate the findings of related experimental and numerical studies

Prevalence of gestational diabetes mellitus using IADPSG and DIPSI criteria: a cross-sectional study

Background: Considering the magnitude of adverse pregnancy outcomes related to gestational diabetes, the present study was undertaken to find out the prevalence of gestational diabetes mellitus using the international association of diabetes in pregnancy study groups criteria (IADPSG) and diabetes in pregnancy study group India (DIPSI) criteria to ascertain whether the present practice of diagnosing GDM by the guidelines recommended by DIPSI 21 based on WHO criterion of 2-h PG ≥140 mg/dL can still be followed in this study settings or adopt IADPSG recommendation.Methods: This study was done at Antenatal Clinic, department of obstetrics and gynecology, KLES Dr Prabhakar Kore Hospital, Belgaum from January 2013 to December 2013. A total of 225 pregnant women between 24 to 28 weeks gestations were studied. Diagnosis and the prevalence of GDM were assessed by applying both DIPSI and IADPSG criteria.Results: Most of the women (58.11%) were between 22 to 25 years and the mean age was 23.78±3.38 years. Based on the IADPSG criteria, the prevalence of GDM was 19.11% and by applying DIPSI criteria, prevalence of GDM was 16.89%. The difference in diagnostic capability between IADPSG and DIPSI was found to be 2.8% and the kappa statistics showed good strength of agreement between the two tests (p>0.302; Kappa=0.774).Conclusions: It was concluded that, the diagnosis GDM based on DIPSI is as effective as IADPSG criteria. Further, in resource poor countries like India, DIPSI procedure would be used with an advantage of being less costly and without compromising the clinical equipoise.

Effects of second diffusing component and cross diffusion on primary and secondary thermoconvective instabilities in couple stress liquids

Linear and weakly nonlinear analyses are made for the Rayleigh-B´enard convection in two-component couple-stress liquids with the Soret effect. Conditions for pitchfork, Hopf, Takens-Bogdanov, and codimension-two bifurcations are presented. The Lorenz model is used to study the inverted bifurcation. Positive values of the Soret co-efficient favor a pitchfork bifurcation, whereas negative values favor a Hopf bifurcation. Takens-Bogdanov and codimension-two bifurcations are not as much influenced by the Soret coefficient as pitchfork and Hopf bifurcations. The influence of the Soret coefficient on the inverted bifurcation is similar to the influence on the pitchfork bifurcation. The in-fluence of other parameters on the aforementioned bifurcations is also similar as reported earlier in the literature. Using the Newell-Whitehead-Segel equation, the condition for occurrence of Eckhaus and zigzag secondary instabilities is obtained. The domain of ap-pearance of Eckhaus and zigzag instabilities expands due to the presence of the Soret coefficient for positive values. The Soret coefficient with negative values enhances heat transport, while positive values diminish it in comparison with heat transport for the case without the Soret effect. The dual nature of other parameters in influencing heat and mass transport is shown by considering positive and negative values of the Soret coefficient. © 2017, Shanghai University and Springer-Verlag GmbH Germany