Sustainable carbon sequestration via olivine based ocean alkalinity enhancement in the east and South China Sea: Adhering to environmental norms for nickel and chromium.

Enhancing silicate weathering to increase oceanic alkalinity, thereby facilitating the absorption of atmospheric carbon dioxide (CO2), is considered a highly promising technique for carbon sequestration. This study aims to evaluate the feasibility and potential of olivine-based ocean alkalinity enhancement (OAE) for the removal of atmospheric CO2 and its storage in seawater as bicarbonates in the East and South China Seas (ESCS). A particular focus is placed on the potential ecological impacts arising from the release of nickel (Ni) and chromium (Cr) during the olivine weathering process. We considered two extreme scenarios: one where Ni and Cr are entirely retained in seawater, and another where they are completely deposited in sediments. These scenarios respectively represent the maximum permissible concentrations of Ni and Cr in seawater and sediments during the OAE process. Current marine environmental quality standards (EQS) were utilized as the threshold limits for Ni and Cr in both seawater and sediment, with concentrations exceeding these EQS potentially leading to significant adverse effects on marine life. When all released Ni is retained in seawater, the allowable dosage of olivine varies from 0.05 to 13.7 kg/m2 (depending on olivine particle size, temperature, and water depth); when all released Ni is captured by sediment, the permissible addition of olivine ranges from 0.21 to 2.1 kg/m2 (depending on mixing depth). Given the low solubility of Cr, it is not necessary to consider the scenario where Cr exceeds the limit in seawater. The allowable amount of Cr entirely retained in sediments ranges from 0.69 to 47.2 kg/m2.In most scenarios, the accumulation of metals in sediments preferentially exceeds the corresponding threshold value rather than remaining in seawater. Therefore, we recommend using alkalization equipment to fully dissolve olivine before discharging into the sea, enabling a larger-scale application of olivine without significant negative ecological impacts.

Understanding the role of manganese oxides in retaining harmful metals: Insights into oxidation and adsorption mechanisms at microstructure level.

The increasing intensity of human activities has led to a critical environmental challenge: widespread metal pollution. Manganese (Mn) oxides have emerged as potentially natural scavengers that perform crucial functions in the biogeochemical cycling of metal elements. Prior reviews have focused on the synthesis, characterization, and adsorption kinetics of Mn oxides, along with the transformation pathways of specific layered Mn oxides. This review conducts a meticulous investigation of the molecular-level adsorption and oxidation mechanisms of Mn oxides on hazardous metals, including adsorption patterns, coordination, adsorption sites, and redox processes. We also provide a comprehensive discussion of both internal factors (surface area, crystallinity, octahedral vacancy content in Mn oxides, and reactant concentration) and external factors (pH, presence of doped or pre-adsorbed metal ions) affecting the adsorption/oxidation of metals by Mn oxides. Additionally, we identify existing gaps in understanding these mechanisms and suggest avenues for future research. Our goal is to enhance knowledge of Mn oxides' regulatory roles in metal element translocation and transformation at the microstructure level, offering a framework for developing effective metal adsorbents and pollution control strategies.

Toward Human-Like Grasp: Functional Grasp by Dexterous Robotic Hand Via Object-Hand Semantic Representation.

Intelligent robotic manipulation is a challenging study of machine intelligence. Although many dexterous robotic hands have been designed to assist or replace human hands in executing various tasks, how to teach them to perform dexterous operations like human hands is still a challenge. This motivates us to conduct an in-depth analysis of human behavior in manipulating objects and propose an object-hand manipulation representation. This representation provides an intuitive and clear semantic indication of how the dexterous hand should touch and manipulate an object based on the object's own functional areas. At the same time, we propose a functional grasp synthesis framework, which does not require real grasp label supervision, but relies on the guidance of our object-hand manipulation representation. In addition, in order to obtain better functional grasp synthesis results, we propose a network pre-training method that can make full use of easily obtained stable grasp data, and a network training strategy to coordinate the loss functions. We conduct object manipulation experiments on a real robot platform, and evaluate the performance and generalization of our object-hand manipulation representation and grasp synthesis framework.

Evidence for the 2:1 molecular recognition and inclusion behaviour between beta- and gamma-cyclodextrins and cinchonine.

Cinchonine (Cin) is the primary drug of choice in the treatment of malaria, but its poor solubility has restricted its use via the oral route. Cyclodextrins (CDs) form inclusion complexes with cinchonine to form soluble complexes. This interaction was investigated by solubility studies, electrospray ionization mass spectrometry (ESI-MS), and molecular modeling. ESI-MS evaluated successfully the nature of the solution-phase inclusion complexes. The experimental results showed that not only 1:1, but also stable 2:1 inclusion complexes can be formed between CDs and Cin. Multi-component complexes of beta-CD-Cin-beta-CD (1:1:1), gamma-CD-Cin-gamma-CD (1:1:1), and beta-CD-Cin-gamma-CD (1:1:1) were found in equimolar beta- and gamma-CD mixtures with Cin. The formation of 2:1 and multi-component 1:1:1 non-covalent CD-Cin complexes indicates that beta- and gamma-CD are able to form sandwich-type inclusion complexes with Cin in high concentrations. The phase-solubility diagram showed non-linear type A(p) profile, indicating that more than one cyclodextrin molecule is involved in the complexation of one guest molecule. Molecular modeling calculations have been carried out to rationalize the experimental findings and predict the lowest energy molecular structure of inclusion complex.