A Simple and Practical Theoretical Model for Interpreting Binary Azeotropes

We put forth a simple and yet practical theoretical model generalized from Raoult’s law and Henry’s law and show that it can be reduced to these two laws under limiting conditions. The model entertains a hybrid parameter h_B with activity coefficient bundled into it, which smoothly bridges the p_B^* and K_B coefficients in Raoult’s law and Henry’s law. The value of h_B falls in the interval of [K_B, p_B^*] or [p_B^*, K_B] in the case of negative or positive deviation from Raoult’s law, respectively. We uncover an overlapping rule for the ranges of h_A and h_B, which binary mixtures must obey to form azeotropes. We also provide straightforward ways to analyze the characteristic mole fraction and pressure for azeotropes and to understand the relative positions of vapor composition curves with respect to the liquid counterparts. We rely heavily on experimental data available in the literature for representative binary mixtures with both negative and positive deviations from Raoult’s law to illustrate the algebraic derivations. The knowledge gained is useful in the analysis of experimental data from vapor-liquid equilibrium measurements and possess pedagogical merit in various relevant fields.

A Simple and Practical Theoretical Model for Interpreting Binary Azeotropes

We put forth a simple and yet practical theoretical model generalized from Raoult’s law and Henry’s law and show that it can be reduced to these two laws under limiting conditions. The model entertains a hybrid parameter h_B with activity coefficient bundled into it, which smoothly bridges the p_B^* and K_B coefficients in Raoult’s law and Henry’s law. The value of h_B falls in the interval of [K_B, p_B^*] or [p_B^*, K_B] in the case of negative or positive deviation from Raoult’s law, respectively. We uncover an overlapping rule for the ranges of h_A and h_B, which binary mixtures must obey to form azeotropes. We also provide straightforward ways to analyze the characteristic mole fraction and pressure for azeotropes and to understand the relative positions of vapor composition curves with respect to the liquid counterparts. We rely heavily on experimental data available in the literature for representative binary mixtures with both negative and positive deviations from Raoult’s law to illustrate the algebraic derivations. The knowledge gained is useful in the analysis of experimental data from vaporliquid equilibrium measurements and possess pedagogical merit in various relevant fields.

Impact of El Niño Southern Oscillation on Rainfall and Rice Production: A Micro-Level Analysis

Monsoon fluctuation due to El Niño Southern Oscillation (ENSO) has a reflective influence on rice production, which is the major food grain crop in India. The impact of ENSO on the spatial variability of summer monsoon rainfall was analyzed from 1950 to 2018 and that on Kharif rice production for the period of 1998–2016. It was clear from the analysis that ENSO had varied influences on rainfall and rice production over different rice-growing districts of Karnataka. During El Niño (strong, moderate, and weak) years, southwest (S-W) monsoon rainfall was below normal in all the districts of Karnataka, wherein the highest negative deviation from normal was recorded in the Mysore district (−21.43%). In contrast, the rice production was higher in 15 districts out of 25, and the deviation from normal ranged from −39.73% in Bidar to 42.11% in Gulbarga district. During the La Niña (strong, moderate, and weak) years, S-W monsoon rainfall was above normal in 12 districts in which Bidar and Bengaluru urban districts have shown the highest positive deviation (19.93 and 19.82%, respectively). However, except for Udupi, Dakshina Kannada, Bidar, Davanagere, and Hassan districts, all the other major rice-growing districts have shown a positive deviation in rice production with the highest deviation of 62.39% in Tumkur district. Additionally, correlation coefficient values indicated the influence of southwest monsoon rainfall on Kharif rice production during El Niño years with a major contribution from September month rainfall. This kind of ENSO impact analysis on spatial rice production could be useful for formulating the farm-level site-specific management, planning, and policy decisions during ENSO periods in advance.

A gap in sedimentation in the Silurian section of the Subpolar Urals at the Ludlow-Pridoli boundary

Research subject. The article discusses the results of a new detailed study of a reference section of the Upper Silurian in the Subpolar Urals. This study was undertaken to clarify the existing contradictions concerning the age of the Ludlow-Pridoli boundary deposits and the definition of the Ludlow-Pridoli boundary, which is based on the study of different fauna groups.Materials and methods. The newly collected collections contained more than 100 samples of sedimentary rocks with fossil macro fauna, 22 tests on microfauna, 198 tests on chemical analysis for determining the content of Ba, Sr and δ13C and δ18O isotopes in carbonates. The results of experiments were confirmed by the authors’ bio-sedimentological, paleo-ecological and chemostratigraphic data.Results. The conducted research confirmed the existence of a gap in sedimentation at the end of Ludlow; clarified the thickness of the Sizim stage in the reference section; elucidated its sedimentological and chemostratigraphic characteristics; allowed changes in biodiversity due to a change in the sedimentation regime, paleoecological impact on biota in the late Ludlow and restoration of biota in the early Pridoli to be traced. The study also demonstrated that the time boundaries of the transgressive and regressive stages in the development of the Northern Ural sea basin and the event-stratigraphic boundary of the Ludlow-Pridoli were directly related to the main global events in the Late Silurian (Lau Event, Lower Pridolian Event), the traces of which are preserved in the studied section.Conclusions. The intensification of regressive tendencies across the largest part of the Northern Ural paleobasin in the Late Ludlow, widespread development of microbial biota, cessation of the Silurian reef formation, as well as the extinction of Pentamerida brachiopods – exclusively, indicate a significant ecosystematic restructuring in the late Ludlow. It can be assumed that the absence of a significant positive deviation of the δ13C global Lau Event in this section is associated with the identified gap, the amplitude of which correlates with the Ozarkodina snajdri and Ozarkodina crispa zones located above the Polygnathoides siluricus zone in the conodont sequence of the Upper Ludlow.

EFFECT OF PANDEMIC ON STOCK PRICE BEHAVIOUR WITH SPECIAL REFERENCE TO S&P BSE HEALTHCARE INDEX

The outburst of pandemic has caused widespread disorder in the country and the stock market is not also free from its grip. Despite the decrement in the performance of sectoral indices, the pharma sector has outperformed in both the NSE and BSE stock exchanges. The present study focuses on the market behavior of S&P BSE Healthcare Index and its top ten constituent companies’ pre and post pandemic outbreak. The market behavior is measured in terms of the closing price of the index and its constituents which is being studied by using t-test. The results of the study indicated that there is no deviation in the performance of S&P BSE Healthcare Index after the outburst of pandemic. While eight of its constituent companies showed deviation in their performance post pandemic outbreak. Out of which most of the companies showed positive deviation post pandemic outburst. Therefore, it would be beneficial for the investors to invest in the pharma sector stocks amid the national crisis. KEYWORDS: Pandemic, Epidemic, Risk, Pharma sector.

Spectral Properties of Laser Dyes at varying Temperature

Spectral properties of laser dyes 4-methyl-7-(4-morpholinyl)-2 H pyrano [2,3-b] pyridin-2-one (LD – 425) and 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoromrthyl)-2H-pyrano[2,3b][1,8]naphthyridin-2-one (LD – 489) have been investigated in the temperature range 250C - 650C by steady state and transient methods. Fluorescence intensity decreases with increase in temperature with fluorescence band maxima shifted towards shorter wavelength in both the dyes. Further, fluorescence lifetime has decreased with increase in temperature for LD - 425, whereas remained constant with change in temperature for LD - 489. The possible deactivation mechanisms are discussed. The quenching effect of these dyes in the presence of aniline at different temperature has been studied and the Stern-Volmer (S-V) plots are non-linear showing positive deviation. It has been observed that dynamic quenching constant increases with temperature, whereas static quenching constant is independent of temperature.

Isothermal Vapor-Liquid Equilibrium Measurement of Isobutanol + Isooctane/N-Heptane Binary Mixtures at Temperatures Range of 303.15-323.15 K

The addition of alcohol as an oxygenated compound in gasoline blends may increase the vapor pressure of gasoline mixture. As a result, the study of vapor-liquid equilibrium for gasoline component and alcohol is necessary. In this study, the vapor-liquid equilibrium of isobutanol – isooctane/n-heptane blends were obtained experimentally at temperatures in the range 303.15 to 323.15 K using modified simple quasi-static ebulliometer. The apparatus was validated by comparing the vapor pressure of pure isobutanol, isooctane, and n-heptane with the published data and giving average absolute deviation (AAD) between experimental and calculated ones with magnitude less than 1.0%. The addition of isobutanol with the mole fraction range from 0.2 to 0.6 would increase the vapor pressure of the isooctane and n-heptane up to 12% and 14% respectively. The vapor pressure of binary mixtures was correlated with the Wilson, Non-random two-liquid (NRTL), and Universal quasi-chemical (UNIQUAC) equations with AAD 1.6%, 1.5%, and 1.7%, respectively for isobutanol + isooctane system and 1.8%, 1.7%, and 2.0%, respectively for isobutanol + n-heptane system. The systems studied show positive deviation from Raoult’s Law.

Assessment of Better Prediction of Seasonal Rainfall by Climate Predictability Tool Using Global Sea Surface Temperature in Bangladesh

This study was conducted to determine better prediction result of seasonal rainfall. To evaluate the better prediction of seasonal rainfall of rainy season (15 June-15 August) by Climate Predictability Tools (CPT) in the context of using sea surface temperature (SST) of starting month of rainy season compare to using SST of one month before the rainy season. The study was carried out at the South Asian Association for Regional Cooperation Meteorological Research Centre, Dhaka; Bangladesh between January and December, 2010. A correlation between rainfall at Rangpur, Dhaka, Barisal and Sylhet and global SST of different areas of the world was studied by using the both data of 1975- 2008 years with the help of the CPT to find more positive correlated SST with observed rainfall and use as predictor for giving the prediction of the year 2009. The statistical method applied using CPT which is canonical correlation analysis. Using SST of one month before rainy season as predictor, the positive deviation of predicted rainfall from observed rainfall was 1.34 mm/day at Sylhet and 0.9 mm/day at Dhaka. The negative deviation of mean rainfall was 1.16 mm/day at Rangpur and 1.10 mm/day at Barisal. Again, using of starting one month SST of rainy season as predictor, positive deviation of predicted rainfall from observed rainfall was 4.03 mm/day at Sylhet. The positive deviation of daily mean rainfall was found 6.58 mm/day at Dhaka and 6.23 mm/day over southern Bangladesh. The study reveals that SST of one month before rainy season was better predictor than SST of starting month of rainy season.