CHARACTERISATION OF MULTIPHASE FLUID-STRUCTURE INTERACTION USING NON-INTRUSIVE OPTICAL TECHNIQUES

The purpose of this study is to determine experimentally the effectiveness of passive drag reduction techniques (which involve adjusting surface geometry) within a chaotic multiphase flow system. To quantify the intrusion and disturbance caused, a liquid-air blast atomiser continuously discharges within a test section of air at atmospheric pressure, with a circular cylinder placed 25 cylinder diameters (250 mm) downstream of the nozzle. This cylinder is then replaced with other cylinders which have modified surface geometry. The data was obtained using Particle Image Velocimetry (PIV) and determines the fluid motion resulting from spray structure interaction of a liquid spray with a circular cylinder. Subtraction of non intruded spray images from intruded spray images at the same locations, using the time averaged analysis allows the direct comparison of the amount of disturbance each geometric variant has on the spray. Using this data alongside velocity profiles time averaged trends were compared. Drag reduction from V-shaped grooves provides the greatest disturbance reduction. This is due to the reduced shear stress around its cross section and the addition of small liquid eddies within each V-groove creates a gliding surface. These features proved to be most effective when monitoring drag reduction in multiphase flow-structure interaction

Evaluation of drug use health related quality of life and pharmacoeconomics in autoimmune skin disorders: focus on blistering skin disorders-a prospective observational study

Background: Autoimmune skin disorders (ASDs) are complex diseases triggered by autoantibodies action against epidermal antigens or the dermo epidermal junction. Although rare, they present high morbidity, affecting the quality of life (QoL) of patients and financial status of patient.Methods: This prospective, observational study was carried out in department of dermatology for 2-3 months after ethical approval. Drug usage pattern, heath related QoL (HRQOL) by using DLQI (Dermatology life quality index) and cost were evaluated in patients with ASDs. Statistical analysis was done using Microsoft excel office 2019 and rechecked with SPSS (version 23.0). P<0.001 was considered as statistically significant.Results: Out of 73 patients enrolled, 32 were male and 41 were female with the mean age was 48.27±14.93 years; 55% patients had autoimmune blistering skin disorders (AIBDs) and 45% having other ASDs (OADs). Pemphigus vulgaris (PV) (35%) being the most common among all ASDs. Systemic steroid (60.27%), topical steroid (79.45%), levocetirizine (63%) were most commonly prescribed drugs. Mean DLQI score at baseline and after treatment was 11.64±2.49 and 6.8±2.75 respectively. It was highly significant statistically (p<0.0001). Total cost of illness per month was 813.64±481.21 INR. Maximum percentage variation in cost was seen with prednisolone (1706.28%).Conclusions: ASDs have a female bias and inflict severe impairment to the QoL of patients. Appropriate drug therapy with corticosteroids and other adjuvant drug lead to positive impact on QoL. There was very wide price variation of different brands of the same generic most commonly prednisolone and levocetirizine

Geometrical characterization of healthy red blood cells using digital holographic microscopy and parametric shape models for biophysical studies and diagnostic applications

Modeling of the red blood cell (RBC) shape is an integral part of the experimental and computer simulation investigations of light scattering by these cells for fundamental studies as well as diagnostic applications in the techniques like cytometry. In the present work, a comprehensive study of the geometrical characterization of healthy human RBCs using the digital holographic microscopy (DHM) and six frequently employed parametric shape models is reported. It is shown that the comparison of the optical phase profiles, the thickness profiles given by the models with the DHM results gives a better judgement of the appropriateness of the parametric shape models. Results of geometrical characterization of 500 healthy RBCs in terms of volume, surface area and sphericity index lead to the classification of the parametric models in two categories based on the nature of variation of these quantities with the cell diameter. In light of the variability of the healthy RBC shapes, our findings suggest that the parametric models exhibiting a negative correlation between the sphericity index and the cell diameter would provide more reliable estimates of the RBC parameters in diagnostic applications. Statistical distributions and descriptive statistics of the RBC volume, surface area and sphericity index serve as a guide for the assessment of the capability of the studied parametric models to give a reliable account of the variability of the healthy RBC shape and size.Comment: 25 pages, 17 figure

Two photon absorption in Mn<SUP>2+</SUP>-doped ZnSe quantum dots

The nonresonant third order nonlinear optical properties of three different sized Mn2+-doped ZnSe quantum dots (QDs) are investigated. The nonlinear absorption is measured at 532 nm using 35 picosecond laser pulses in an open-aperture Z-scan setup. Two photon absorption (2PA) cross-section in ZnSe QDs is found to be three orders of magnitude higher than its bulk value. These nanostructures show size dependent nonlinear absorption coefficients. It is found that the 2PA further enhances with decrease in size of the QD and is twice that of its undoped counterpart due to change in the local electric field

Two-photon absorption in ZnSe and ZnSe/ZnS core/shell quantum structures

The third order nonlinear optical properties of two different sized ZnSe and ZnSe/ZnS quantum dots (QDs) are investigated. The nonlinear absorption is measured at 806 nm using Ti:sapphire 100 fs laser pulses in an open aperture Z-scan setup. Two-photon absorption (2PA) is found to be dominant in core and core shell QDs. 2PA cross section is enhanced by three orders of magnitude compared bulk ZnSe. 2PA cross section is observed to increase with reduction in QD diameter, due to strong confinement effect. ZnSe/ZnS QDs exhibit higher 2PA cross section compared with corresponding ZnSe QDs, indicating better passivation of the QD surface