Rapid transitions between defect configurations in a block copolymer melt

With in situ scanning force microscopy, we image the ordering of cylindrical microdomains in a thin film of a diblock copolymer melt. Tracking the evolution of individual defects reveals elementary steps of defect motion via interfacial undulations and repetitive transitions between distinct defect configurations on a time scale of tens of seconds. The velocity of these transitions suggests a cooperative movement of clusters of chains. The activation energy for the opening/closing of a connection between two cylinders is estimated.     

Characterization of SARS-CoV-2 Escape Mutants to a Pair of Neutralizing Antibodies Targeting the RBD and the NTD

Mutations in the spike protein of SARS-CoV-2 can lead to evasion from neutralizing antibodies and affect the efficacy of passive and active immunization strategies. Immunization of mice harboring an entire set of human immunoglobulin variable region gene segments allowed to identify nine neutralizing monoclonal antibodies, which either belong to a cluster of clonally related RBD or NTD binding antibodies. To better understand the genetic barrier to emergence of SARS-CoV-2 variants resistant to these antibodies, escape mutants were selected in cell culture to one antibody from each cluster and a combination of the two antibodies. Three independently derived escape mutants to the RBD antibody harbored mutations in the RBD at the position T478 or S477. These mutations impaired the binding of the RBD antibodies to the spike protein and conferred resistance in a pseudotype neutralization assay. Although the binding of the NTD cluster antibodies were not affected by the RBD mutations, the RBD mutations also reduced the neutralization efficacy of the NTD cluster antibodies. The mutations found in the escape variants to the NTD antibody conferred resistance to the NTD, but not to the RBD cluster antibodies. A variant resistant to both antibodies was more difficult to select and only emerged after longer passages and higher inoculation volumes. VOC carrying the same mutations as the ones identified in the escape variants were also resistant to neutralization. This study further underlines the rapid emergence of escape mutants to neutralizing monoclonal antibodies in cell culture and indicates the need for thorough investigation of escape mutations to select the most potent combination of monoclonal antibodies for clinical use.     

新型强塑性变形—静液循环挤压压缩加工AZ91镁合金及其表征

通过静液循环挤压压缩(HCEC)强塑性变形法加工具有较大高径比的密排六方金属棒,并研究其性能.对AZ91镁合金进行两个连续循环加工,研究其显微组织演化、力学性能和腐蚀行为.结果表明,HCEC加工可成功制备超细晶镁合金长棒材,且可同时提高其强度和韧性.经二次循环加工后,样品的抗拉强度和伸长率分别为铸态样品的2.46倍和3...     

MiHOS: an approach to support handling the mismatches between system requirements and COTS products

In the process of selecting Commercial Off-The-Shelf (COTS) products, it is inevitable to encounter mismatches between system requirements and COTS products. These mismatches occur as a result of an excess or shortage of the COTS attributes. This paper proposes a decision support approach, called MiHOS (Mismatch Handling for COTS Selection), that aims at addressing COTS mismatches during and after the selection process. MiHOS can be integrated with existing COTS selection methods at two points: (1) For evaluating COTS candidates: MiHOS estimates the anticipated fitness of the candidates if their mismatches are resolved. This helps to base our COTS selection decisions on the fitness that the candidates will eventually have if selected. (2) Mismatch resolution after selecting a COTS product: MiHOS suggests alternative plans for resolving the most appropriate mismatches using suitable actions, such that the most important risk, technical, and resource constraints are met. A case-study is used to illustrate MiHOS and to discuss its added value.

Superbiphilic Laser-Microengineered Surfaces with A Self-Assembled Monolayer Coating for Exceptional Boiling Performance

The rapid advancement of engineering systems has spurred the search for innovative thermal management solutions. Boiling, as a phase-change heat transfer method, has shown promise in heat dissipation, but non-functionalized surfaces struggle with increasing cooling demands. To improve heat dissipation efficiency across different heat loads, functionalized surfaces with tailored wettability have been proposed. Separately, superhydrophilic and superhydrophobic surfaces each offer benefits and drawbacks in boiling applications but combining them on a single “biphilic” surface simultaneously harnesses their advantages. In this study, laser-functionalized copper surfaces with spatially tailored wettability are developed by combining two-step laser texturing with a self-assembled monolayer coating, while focus is placed on the impact of the size and pitch of superhydrophobic spots. The developed functionalized surfaces exhibit exceptional boiling performance with heat transfer coefficients up to 299 kW m⁻² K⁻¹, a 434% enhancement over untreated surfaces. Optimal ratios of superhydrophilic and superhydrophobic areas and optimal spot pitch are identified. Additionally, varying behavior at different heat flux levels is observed, emphasizing the importance of considering thermal loads when determining the optimal surface pattern. This advancement in performance, along with the rapid and cost-effective functionalization process, represents a significant breakthrough for enhanced thermal management applications.     

Nucleation behaviour and microstructure of single Al-Si12 powder particles rapidly solidified in a fast scanning calorimeter

The understanding of rapid solidification behaviour, e.g. the undercooling versus growth velocity relationship, is crucial for tailoring microstructures and properties in metal alloys. In most rapid solidification processes, such as additive manufacturing (AM), in situ investigation of rapid solidification behaviour is missing because of the lack of accurate measurement of the cooling rate and nucleation undercooling. In the present study, rapid solidification of single micro-sized Al-Si12 (mass%) particles of various diameters has been investigated via differential fast scanning calorimetry employing controllable cooling rates from 100 to 90,000 K s^?1 relevant for AM. Based on nucleation undercooling and on microstructure analysis of rapidly solidified single powder particles under controlled cooling rates, two different heterogeneous nucleation mechanisms of the primary α-Al phase are proposed. Surface heterogeneous nucleation dominates for particles with diameter smaller than 23 μm. For particles with diameter larger than 23 μm, the nucleation of the primary α-Al phase changes from surface to bulk heterogeneous nucleation with increasing cooling rate. The results indicate that at large undercoolings (>?95 K) and high cooling rates (>?10,000 K s^?1), rapid solidification of single particle can yield a microstructure similar to that formed in AM. The present work not only proposes new insight into rapid solidification processes, but also provides a theoretical foundation for further understanding of microstructures and properties in additively manufactured materials.

     

Effect of Slime and Impurity Removal as a Pre-Treatment Stage Using a Low-Grade Zinc-Oxide Sample

Russian Journal of Non-Ferrous Metals - A low-grade zinc-oxide sample (6–8% Zn) from Mehdiabad mine in Iran, with a high amount of slime and iron (17–19% Fe) and manganese (5–7%...     

AI-Based Supervision for a Stirred Extraction Column Assisted with Population Balance-Based Simulation

Solvent extraction as environmental benign separation technique can be modeled in physical detail by population balance of the droplet size distribution. However, much information on the droplet generation and coalescence is necessary for representative results. In this contribution, we present a comparison of AI-evaluated experimental and simulated data on the behavior of a stirred solvent extraction column with an inner diameter of 32 mm. Lab experiments were performed using the standard test system with n-butyl acetate, acetone, and deionized water. A digital camera is placed in front of the middle section as well as the head of the column. Droplet size evaluation is performed using a retrained neural net (Mask R-CNN). The stirred DN32 extraction column is modeled and simulated using a 1D CFD population balance software. The simulation allows for behavior analysis, trends comparison, and validation of the hydrodynamics and mass transfer performances.