Effects of Variable Viscosity and Temperature Modulation on Linear Rayleigh-Bénard Convection in Newtonian Dielectric Liquid

The linear Rayleigh-Bénard electro-convective stability of the Newtonian dielectric liquid is determined theoretically subject to the temperature modulation with time. A perturbation method is used to compute the critical Rayleigh number and the wave number. The critical Rayleigh number is calculated as a function of the frequency of modulation, the temperature-dependent variable viscosity, the electric field dependent variable viscosity, the Prandtl number, and the electric Rayleigh number. The effects of all three cases of modulations are established to delay or advance the onset of the convection process. In addition, how the effect of variable viscosity controls the onset of convection is studied

Effect of hydrogen bonding and solvent polarity on the fluorescence quenching and dipole moment of 2-methoxypyridin-3-yl-3-boronic acid

Two photophysical properties namely, fluorescence quenching and dipole moment (both ground state and excited state) of 2-methoxypyridin-3-yl-3-boronic acid (2MPBA) have been investigated in alcohol environment using steady state fluorescence technique at 300 K. In quenching studies, a rare but not unusual observation; negative Stern-Volmer (S-V) deviation has been noticed. It has been explained using the concept of solute’s conformational changes in the ground state due to inter-molecular and intra-molecular hydrogen bonding in alcohol environment. The spectroscopic data has been processed using Lehrer equation and thereby Stern-Volmer constant (KSV) has been evaluated. It has been found to be above 100 for most of the solvents used. The data related to dipole moment has been examined using different solvent polarity functions. Theoretical calculation of dipole moment in the ground state has been done using Gaussian software. The general solute–solvent interactions and hydrogen bond interactions have been found to be operative. An appreciable red shift of about 25 nm in the emission spectra has been identified with the rise in solvent polarity and decrease in molar mass of alcohols. It confirms the π→π* transition as well as the possibility of intra-molecular charge transfer (ICT) character in the emitting singlet state of 2MPBA

First in situ estimations of small phytoplankton carbon and nitrogen uptake rates in the Kara, Laptev, and East Siberian seas

Carbon and nitrogen uptake rates by small phytoplankton (0.7–5&thinsp;µm) in the Kara, Laptev, and East Siberian seas in the Arctic Ocean were quantified using in situ isotope labeling experiments; this research, which was novel and part of the NABOS (Nansen and Amundsen Basins Observational System) program, took place from 21 August to 22 September 2013. The depth-integrated carbon (C), nitrate (NO3−), and ammonium (NH4+) uptake rates by small phytoplankton ranged from 0.54 to 15.96&thinsp;mg&thinsp;C&thinsp;m−2&thinsp;h−1, 0.05 to 1.02&thinsp;mg&thinsp;C&thinsp;m−2&thinsp;h−1, and 0.11 to 3.73&thinsp;mg&thinsp;N&thinsp;m−2&thinsp;h−1, respectively. The contributions of small phytoplankton towards the total C, NO3−, and NH4+ varied from 25&thinsp;% to 89&thinsp;%, 31&thinsp;% to 89&thinsp;%, and 28&thinsp;% to 91&thinsp;%, respectively. The turnover times for NO3− and NH4+ by small phytoplankton found in the present study indicate the longer residence times (years) of the nutrients in the deeper waters, particularly for NO3−. Additionally, the relatively higher C and N uptake rates by small phytoplankton obtained in the present study from locations with less sea ice concentration indicate the possibility that small phytoplankton thrive under the retreat of sea ice as a result of warming conditions. The high contributions of small phytoplankton to the total C and N uptake rates suggest the capability of small autotrophs to withstand the adverse hydrographic conditions introduced by climate change.</p

Enhancing routing efficiency in social internet of things: R-OPTICS and vEBT based congestion free model

The emergence of the social internet of things (SIoT) network has brought forth distinctive challenges, including node mobility and varying densities, leading to congestion and hampered network efficiency. To overcome these issues, a congestion-free routing model for SIoT is proposed. This model combines the relationship-ordering points to identify the clustering structure (R-OPTICS) algorithm for intelligent node clustering based on relationships and ordering,along with a van emde boas tree (vEBT) for efficient path selection. R-OPTICS enables effective network management by clustering nodes appropriately. The model’s performance is evaluated using metrics such as Rand-Index (1.5765),Davies-Bouldin (-0.4305), and Silhouette Coefficient (1.71685) to assess average goodness values. vEBT identifies optimal paths between clusters, facilitating smart routing decisions. The primary objective of the model is to enhance network efficiency and alleviate congestion by intelligently routing data between clusters. Through extensive simulations, the proposed model outperforms existing routing methods, resulting in improved efficiency and congestion reduction. This congestion-free routing model presents a promising solution to address the unique challenges of SIoT networks, ensuring optimal performance and effective resource management

Biocompatible Maghemite Nanoparticles Compatibilization of GG/CMC Blends in Aqueous Solution

Biocompatible polymer blends with natural polymer guar gum (GG), and a modified naturalpolymer carboxymethylcellulose (CMC) have been studied for their compatibilization withbiocompatible maghemite magnetic nanoparticles. Ultrasonic velocity, density, and dilutesolution viscometry methods were used to assess the intermolecular interaction between GG andCMC in the presence of maghemite nanoparticles at 30°C and 40°C. The solution state studiesconfirmed that GG/CMC blends are compatible in the presence of maghemite nanoparticle onlyif the GG content is more than 30% in the blend. These biocompatible polymer blend-maghemitenanocomposites can be used for their applications in controlled drug release formulations