Summertime turbulent heat fluxes at East Antarctica over neighbouring rocky and ice shelf sites

During the ninth Indian Scientific Expedition to Antarctica, in the year 1990, a micro-meteorological tower was installed at Maitri (70° S, 12° E) on the rocky terrain and on an experimental basis, on the nearby ice-shelf at the location of Dakshin Gangotri (70° 7¢ S, 11° 7¢ E). The synoptic features strongly influencing over the sites are the southeasterly katabatic winds from the polar cap and/or northerly low level warm and humid winds from the sea. These flows are responsible for the formation of strong surface based inversion and strong convective conditions at the ice shelf and rocky terrain during the minimum and maximum insolation periods, respectively. This paper presents a study of surface layer structure over two contrasting surfaces on near-coastal Antarctica and deals with the significance of the energy exchange processes over the rocky Antarctic region and the parameterization of turbulent fluxes over surfaces having strong inversion/convection conditions. The paper makes use of turbulence structure functions which are different from the conventional one given by Panofsky and Dutton (1984).

Melittin-Based Nano-Delivery Systems for Cancer Therapy

Melittin (MEL) is a 26-amino acid polypeptide with a variety of pharmacological and toxicological effects, which include strong surface activity on cell lipid membranes, hemolytic activity, and potential anti-tumor properties. However, the clinical application of melittin is restricted due to its severe hemolytic activity. Different nanocarrier systems have been developed to achieve stable loading, side effects shielding, and tumor-targeted delivery, such as liposomes, cationic polymers, lipodisks, etc. In addition, MEL can be modified on nano drugs as a non-selective cytolytic peptide to enhance cellular uptake and endosomal/lysosomal escape. In this review, we discuss recent advances in MEL’s nano-delivery systems and MEL-modified nano drug carriers for cancer therapy.

Achieving optimal micro-explosions in stable emulsions by adding water-soluble polymers

The emulsified feedstock technique is to improve the performance of products by using the micro-explosion phenomenon of emulsion. However, an obstacle to some applications of this technology is the contradiction between emulsion stability and micro-explosion intensity. For the first time, adding water-soluble polymers was proposed to solve this problem. Two polymers of xanthan gum (XG) and nonionic polyacrylamide (NPAM) were investigated and the results show that micro-explosions have five forms. As one of these five forms, the intensity of optimal micro-explosion is three orders of magnitude higher than other forms, and adding 0.5% XG increases the probability of optimal micro-explosion from 0% to 60% due to the low surface activity, strong thickening and pseudoplasticity of XG solutions. By contrast, NPAM does not promote micro-explosion because of its strong surface activity. Finally, a new mechanism for micro-explosions related to surface tension, interfacial tension and viscosity is proposed.

Hydrogel tapes for fault-tolerant strong wet adhesion

Fast and strong bio-adhesives are in high demand for many biomedical applications, including closing wounds in surgeries, fixing implantable devices, and haemostasis. However, most strong bio-adhesives rely on the instant formation of irreversible covalent crosslinks to provide strong surface binding. Repositioning misplaced adhesives during surgical operations may cause severe secondary damage to tissues. Here, we report hydrogel tapes that can form strong physical interactions with tissues in seconds and gradually form covalent bonds in hours. This timescale-dependent adhesion mechanism allows instant and robust wet adhesion to be combined with fault-tolerant convenient surgical operations. Specifically, inspired by the catechol chemistry discovered in mussel foot proteins, we develop an electrical oxidation approach to controllably oxidize catechol to catecholquinone, which reacts slowly with amino groups on the tissue surface. We demonstrate that the tapes show fast and reversible adhesion at the initial stage and ultrastrong adhesion after the formation of covalent linkages over hours for various tissues and electronic devices. Given that the hydrogel tapes are biocompatible, easy to use, and robust for bio-adhesion, we anticipate that they may find broad biomedical and clinical applications.

Dynamical drivers of Greenland blocking in climate models

Blocking over Greenland is known to lead to strong surface impacts, such as ice sheet melting, and a change in its future frequency can have important consequences. However, as previous studies demonstrated, climate models underestimate the blocking frequency for the historical period. Even though some improvements have recently been made, the reasons for the model biases are still unclear. This study investigates whether models with realistic Greenland blocking frequency in winter have a correct representation of its dynamical drivers, most importantly, cyclonic wave breaking (CWB). Because blocking is a rare event and its representation is model-dependent, we use a multi-model large ensemble. We focus on two models that show typical Greenland blocking features, namely a ridge over Greenland and an equatorward-shifted jet over the North Atlantic. ECHAM6.3-LR has the best representation of CWB of the models investigated but only the second best representation of Greenland blocking frequency, which is underestimated by a factor of 2. While MIROC5 has the most realistic Greenland blocking frequency, it also has the largest (negative) CWB frequency bias, suggesting that another mechanism leads to blocking in this model. Composites over Greenland blocking days show that the present and future experiments of each model are very similar to each other in both amplitude and pattern and that there is no significant change in Greenland blocking frequency in the future. However, these projected changes in blocking frequency are highly uncertain as long as the mechanisms leading to blocking formation and maintenance in models remain poorly understood.

Characterizing the surface texture of a dense suspension undergoing dynamic jamming

Measurements of the surface velocity and surface texture of a freely propagating shear jamming front in a dense suspension are compared. The velocity fields are captured with particle image velocimetry (PIV), while the surface texture is captured in a separated experiment by observing a direct reflection on the suspension surface with high-speed cameras. A method for quantifying the surface features and their orientation is presented based on the fast Fourier transform of localized windows. The region that exhibits strong surface features corresponds to the the solid-like jammed region identified via the PIV measurements. Moreover, the surface features within the jammed region are predominantly oriented in the same direction as the eigenvectors of the strain tensor. Thus, from images of the free surface, our analysis is able to show that the surface texture contains information on the principle strain directions and the propagation of the jamming front. Graphic Abstract

Surface adsorption and survival of SARS-CoV-2 on frozen meat

The first case of a severe acute respiratory syndrome caused by coronavirus-2 was reported in December 2019 in China. The disease spread globally quickly, causing the 2019–2021 COVID-19 pandemic. The meat industry became concerned over the possibility of transmitting the virus in the slaughterhouse environment. The level of air exchange strongly affects the distribution of SARS-CoV-2 aerosols within the slaughterhouses. The adsorption of the SARS-CoV-2 virus on the surface of the frozen meat is dictated mainly by the interplay of electrostatic forces between the virion and tissue (pH) and environmental conditions (temperature and humidity) in the vicinity of adsorption micro-location. Suppose the virus contaminates the meat surface, whereby pH is 5.5 or less. In that case, it firmly adsorbs due to bonds established by protonated amine group and a hydrogen bond between the COOH group of the viral protein and oxygen in hydroxyl groups present on meat surfaces. The meat surface, coated with a thin water film, interacts with the SARS-CoV-2 virions by establishing strong hydrogen bonds. Although there is no proof of COVID-19 contraction by food consumption, the strong surface adsorption and ability of SARS-CoV-2 to survive meat freezing indicate a potential risk of virus transmission by meat.