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The transmission of viruses/bacteria causes infection predominantly via aerosols. The transmission mechanism of respiratory diseases is complex, which includes direct or indirect contact, large droplet, and airborne routes apart from close contact transmission. With this premise, two modes of droplet evaporation are investigated to understand its significance in airborne disease transmission; a droplet in a contact-free environment, which evaporates and forms droplet nuclei, and a droplet on a hydrophilic substrate (fomite). The study examines mass transport, the deposition pattern of bacteria in the precipitates, and their survival and virulence. The osmotic pressure increases with the salt concentration, inactivating the bacteria embedded in the precipitates with accelerated evaporation. Furthermore, the bacteria's degree of survival and enhanced pathogenicity are compared for both evaporation modes. The striking differences in pathogenicity are attributed to the evaporation rate, oxygen availability, and reactive oxygen species generation. [ABSTRACT FROM AUTHOR]

In the present study, brick kiln slag (BKS) has been utilized for low concentration As(III) adsorption in batch mode. BKS was modified with H2SO4 (SA) and NaOH (SB) for enhancing As(III) uptake capacity. Maximum adsorption capacity (13.7 mg/g) was observed for SA at 298 K, pH = 7.0, adsorbent dose = 0.3 g and time = 70 min which was 1.4 times higher than that of SB. Adsorption data modelled into Freundlich isotherm and pseudo-second-order kinetics. Mass transfer coefficients decreased with increase in As(III) concentration. Film diffusion significantly dominated the adsorption of As(III) ions irrespective of the initial concentration. Dimensionless Sherwood number (Sh) interrelated As(III) concentration (Co) as: Sh = 2.97(Co) –0.376, Sh = 4.12(Co) –0.215, Sh = 4.83(Co) –0.588 for H2SO4 modified, NaOH modified and native slag respectively. Low temperature (298 K) favoured As(III) adsorption (based on ∆G° value). Therefore, the modified slag can be used as an effective adsorbent for As(III) remediation from groundwater. [ABSTRACT FROM AUTHOR]

Starch is extracted from the seeds of a pigmented (Phule Rohini) and a non‐pigmented (Phule Maldandi) Indian sorghum cultivar using same wet milling method for both cultivars. This study is focused on investigation of the effect of the pigment on starch characteristics. Isolated starches differing in color are irradiated with an electron beam dose of 5 kGy and compared by measuring physicochemical, structural, pasting, and digestibility properties. Amylose content increases after irradiation and the increase is greater in the case of Phule Maldandi starch. The pigmented starch shows higher carboxyl content after irradiation which may be due to higher amylopectin content. Granular morphology remains constant after irradiation. Irradiation causes a decrease in swelling power and an increase in pasting viscosity of both starches. Color content of red sorghum starch is not changed significantly after irradiation. The increase in pasting viscosity and solubility of non‐pigmented starch is more drastic in nonpigmented starch than in pigmented starch after irradiation. Resistant starch decreases after irradiation which indicates opening up of granular structure or hydrolytic action of irradiation. Pigmented starch can have potential applications in custard powder and bakery products. [ABSTRACT FROM AUTHOR]

Physical modification of starches using dry heating, gamma and electron beam irradiation are considered greener and more cost effective than using crosslinking chemicals for starch modification. Chemical modification of starches generates lot of downstream waste. Alternatively, dry heating of starches can also be utilized to influence hydrolysis as well as crosslinking of chains and requires no catalyst. Gamma and electron beam irradiation although used largely for preservation of foods can introduce carboxyl groups into starch molecules as well as degrade starch chains. Gamma and electron beam irradiation can hydrolyze as well as cross link starches which can have various applications in food and process industries. Irradiation and dry heating are promising techniques and can be used in conjunction with other modifications type for making specialty and resistant starches. To the best of our knowledge dry heating of starches has not been reviewed. Need was also felt to critically review irradiation techniques since there are many ongoing debates on its implications. [ABSTRACT FROM AUTHOR]

Evaporation kinetics of pendant droplets is an area of immense importance in several applications, in addition to possessing rich fluid dynamics and thermal transport physics. This article experimentally and analytically sheds insight into the augmented evaporation dynamics of paramagnetic pendant droplets in the presence of a magnetic field stimulus. The literature provides information that solutal advection and the solutal Marangoni effect lead to enhanced evaporation in droplets with solvated ions. The main focus of this article is to modulate the thermosolutal advection with the aid of an external magnetic field and comprehend the dynamics of the evaporation process under such complex multiphysics interactions. Experimental observations reveal that the evaporation rate enhances as a direct function of the magnetic moment of the solvated magnetic element ions, thereby pointing at the magnetophoretic and magnetosolutal advection. Additionally, flow visualization by particle image velocimetry illustrates that the internal advection currents within the droplet increase in magnitude and are distorted in orientation by the magnetic field. A mathematical formalism based on magnetothermal and magnetosolutal advection has been proposed via scaling analysis of the species and energy conservation equations. The formalism takes into account all major governing factors, viz., the magnetothermal and magnetosolutal Marangoni numbers, magneto-Prandtl and magneto-Schmidt numbers, and the Hartmann number. The modeling establishes the magnetosolutal advection to be the dominant factor behind the augmented evaporation dynamics. Accurate validation of the experimental internal circulation velocity is obtained from the proposed model. This study reveals rich insight into the magnetothermosolutal hydrodynamics in paramagnetic droplets. [ABSTRACT FROM AUTHOR]

The presence of dispersed inclusions is known to modify the interfacial characteristics in liquids by adsorption–desorption of the ions at interfaces. The present article reports the influencing role of dissolved ions in a polar fluid on its evaporation dynamics. The evaporation dynamics of pendant droplets of aqueous solutions of variant simple salts and concentrations have been experimentally studied. The presence of salts is observed to enhance the evaporation rate (obeying the classical D2 law), and the enhancement has been found to hold a direct proportionality to the concentration of the dissolved salt. Furthermore, it is observed that the degree of enhancement in the evaporation rate is also directly proportional to the solubility of the salt in question. The phenomenon is explained based on the chemical kinetics and thermodynamics of hydration of the ionic species in the polar fluid. The classical evaporation rate constant formulation is found to be inadequate in modeling the enhanced species transport. Additional probing via particle image velocimetry reveals augmented internal circulation within the evaporating salt based drops compared to pure water. Mapping the dynamic surface tension reveals that a salt concentration gradient is generated between the bulk and periphery of the droplet and it could be responsible for the internal advection cells visualized. A thermo-solutal Marangoni and Rayleigh convection based mathematical formulation has been put forward, and it is shown that the enhanced solute-thermal convection could play a major role in enhanced evaporation. The internal circulation mapped from experiments is found to be in good quantitative agreement with the model predictions. Scaling analysis further reveals that the stability of the solutal Marangoni convection surpasses the thermal counterpart with higher salt concentration and solubility. The present article sheds insight into the possible domineering role of conjugate thermohydraulic and mass transport phenomena on the evaporation kinetics aqueous droplets with ionic inclusions. [ABSTRACT FROM AUTHOR]

Sessile droplets seated on superhydrophobic surfaces are known to exhibit internal circulation patterns. The present article experimentally demonstrates and theoretically confirms, for the very first time, that the nature and velocity of the internal circulation in sessile droplets seated on superhydrophobic surfaces are strongly governed by the curvature of the surface and its directionality. Sessile droplets were rested on concave and convex superhydrophobic surfaces, and both with one curvature (cylindrical) and two curvatures (spherical) and varying droplet diameter to curve diameters were studied. Particle image velocimetry (PIV) was employed for flow visualization and quantification. It was observed that increasing convexity of the surface leads to deterioration in the velocity of advection within the droplet, whereas increasing concavity of the surface augments the velocity of circulation. A scaling model based on the effective curvature-modulated change in wettability has been put forward to predict the phenomenon, but it was found to be weak in deducing the circulation velocities. Consequently, potential flow theory is employed and the curvatures are approximated as equivalent wedges, with the rested droplet engulfing the wedge partly. Based on the curvature of the surface, the equivalent included wedge angle is deduced. Flow theory over wedged structures is employed to deduce the changes in the internal velocity in the presence of curved surfaces. The spatiotemporally averaged experimental velocities are found to conform to predictions from the proposed model, and good agreement between the theoretical predictions and experimental observations is achieved. The present findings may have strong implications in thermofluidic transport phenomena or multiphase transport processes at the interfacial and/or microscale.