The Role of Serum NT-proBNP for Predicting Left Ventricular Systolic Dysfunction in Hospitalized Patients in Sri Lanka.

Background/aims: Only a few studies have addressed the role of NT-proBNP in identifying Left Ventricular Systolic Dysfunction (LVSD) in South Asian populations. Therefore, the current study was aimed at assessing the use of serum NT-proBNP in predicting LVSD in a hospitalized population in Sri Lanka. Methods: A random sample of 278 individuals referred for echocardiography at a major Teaching Hospital consented for venous blood samples to be collected for serum NT-proBNP assay by sandwich ELISA. Based on the ejection fraction (LVEF) and fractional shortening (FS), participants were differentiated as LVSD (LVEF<50%, FS≤ 29%) and non-LVSD individuals (LVEF>60%). According to inclusion/exclusion criteria, the final study sample consisted of 100 LVSD patients and 41 non-LVSD individuals. Results: The mean ages of the LVSD and non-LVSD groups were 69.1 (±6.2 years) and 71.4 (±2.4 years) (p=0.066) respectively. The median NT-proBNP value (with IQR) among LVSD patients (528.2 pg/mL,355.2-924.2) was comparatively higher than that of non-LVSD individuals (207.3 pg/mL,177.5-343.0). Strong correlations of NT-proBNP level with LVEF (Spearman rho= -0.84, p<0.001) and FS (rho= -0.81, p<0.001) suggested that serum NT-proBNP concentration increases in parallel to deteriorating left ventricular functions. The AUROC of serum NT-proBNP for differentiating LVSD was 0.859 (95% CI:0.79 - 0.92) and the optimal cut-off level for predicting LVSD was 265pg/mL, with 90% sensitivity and 70% specificity. Conclusion: Current Sri Lankan study revealed a considerable correlation of serum NT-proBNP level with LVSD and utilizing such an assay for screening will facilitate adequate evidence to rule-out LVSD among high-risk residents.

Using Biosignals for Objective Measurement of Presence in Virtual Reality Environments.

The concept of 'presence' in the context of virtual reality (VR) refers to the experience of being in the virtual environment, even when one is physically situated in the real world. Therefore, it is a key parameter of assessing a VR system, based on which, improvements can be made to it. To overcome the limitations of existing methods that are based on standard questionnaires and behavioral analysis, this study proposes to investigate the suitability of biosignals of the user to derive an objective measure of presence. The proposed approach includes experiments conducted on 20 users, recording EEG, ECG and electrodermal activity (EDA) signals while experiencing custom designed VR scenarios with factors contributing to presence suppressed and unsuppressed. Mutual Information based feature selection and subsequent paired t-tests used to identify significant variations in biosignal features when each factor of presence is suppressed revealed significant (p < 0.05) differences in the mean values of EEG signal power and coherence within alpha, beta and gamma bands distributed in specific regions of the brain. Statistical features showed a significant variation with the suppression of realism factor. The variations of activity in the temporal region lead to the assumption of insula activation which may be related to the sense of presence. Therefore, the use of biosignals for an objective measurement of presence in VR systems indicates promise.

Composites of ZnO nanoparticles and biomass based activated carbon: adsorption, photocatalytic and antibacterial capacities.

Composite material (AC-ZnO) was prepared by growing ZnO nanoparticles during the production of biomass based-activated carbon (AC) via the incorporation of zinc acetate in the process. Comprehensive analyses confirmed the presence of ZnO nanoparticles over the AC surface and described the particular nature of the composite adsorbent. Methylene blue (MB) equilibrium data fitted the Dubinin-Radushkevich model. The MB adsorption capacity was higher for the bare activated carbons (197.9-188.7 mg/g) than the activated carbons with ZnO nanoparticles (137.6-149.7 mg/g). The adsorption of the MB on the adsorbents is physical because the mean adsorption energy (E) is between 1.76 and 2.00 kJ/mol. Experiments that combine adsorption and photocatalysis were carried out with different loads of adsorbents and with and without UV-light exposure. Photocatalytic activity was identified mostly at the first stage of the adsorption process and, in the case of experiments with less load of the composite AC-ZnO, because the light obstruction effect of the activated carbon is more for higher loads. The ZnO grown over AC improves the adsorption of cations such as Pb, Al and Fe in aqueous phase (polluted river water) and provides antibacterial capacity against Escherichia coli and Salmonella typhimurium.