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The purpose of this study is to develop a monolayer surface coating of stearic acid on Sn-Ag-Cu solder powder to limit oxidation.

Stearic acid was adsorbed onto Sn-Ag-Cu solder powder through liquid-phase adsorption. The isotherm of adsorption was measured and then the microstructure of coated powder was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy.

The adsorption isotherm of stearic acid on the powder was “H” type, which revealed the layer-by-layer adsorption on non-porous surface. When the concentration of solution was in the range of 0.001-0.006 mol/L, with an adsorption amount of 0.12 ± 0.1 mg/g, monolayer stearic acid covered the solder powder completely. Uniform and integrated self-assembled monolayer coating was formed through hydrogen bonds between the oxygen ions in surface lattice of Sn3.0Ag0.5Cu solder powder and the —O—H hydroxyl group of stearic acid. The maximum angle of stability of coated powder also reduced by 2.87° compared with that of non-coated powder. The increase rate of oxygen content of coated powder was much slower than that of non-coated powder when they were exposed to humid air.

As a result, oxidation of fine solder powder was effectively limited. Essentially, this method can also be applied to the coating of other types of solder powder and has reference significance to other coating by liquid-phase method.

To explore substitutes for traditional Sn-Pb solder, Sn-20In-2.8Ag was considered because of its appropriate melting temperature, good reliability and high ductility at less than 100°C. However, the mechanical properties of Sn-20In-2.8Ag were not satisfactory. The reason for the poor mechanical properties of the Sn-20In-2.8Ag/Cu joint was revealed, and a way to solve the problem was found.

The microstructure evolution, characteristics of melting and solidification and joining performance with Cu were investigated using scanning electron microscopy (SEM), electron probe microanalysis, differential scanning calorimetry (DSC) and mechanical testing.

SEM results showed that the microstructure of Sn-20In-2.8Ag was composed of coarse dendritic Ag₂In and γ phases, with Ag₂In distributed at the grain boundaries. DSC measurements revealed that small amount of low temperature eutectic reaction, L → Ag₂In + β + γ, occurred at 112.9°C. This reaction was caused by the segregation of indium, which is a process that has a strong driving force. In the lap-shear testing, a crack propagated along the grain boundary of the solder, and failure showed an intergranular fracture. This failure was connected with the three-phase eutectic and coarse Ag₂In. Thus, to improve the mechanical properties, segregation of indium should be reduced and coarsening of Ag₂In should be prevented.

The reason for the unsatisfactory mechanical properties of Sn-20In-2.8Ag was revealed via microstructural observations and solidification analysis, and the way to solve this problem was found.

The purpose of this paper is to explore the effect of ZnO on the structure and properties of micro-arc oxidation (MAO) coating on rare earth magnesium alloy under large concentration gradient.

The macroscopic and microscopic morphology, thickness, surface roughness, chemical composition and structure of the coating were characterized by different characterization methods. The corrosion resistance of the film was studied by electrochemical and scanning Kelvin probe force microscopy. The results show that the addition of ZnO can significantly improve the compactness and corrosion resistance of the MAO coating, but the high concentration of ZnO will cause microcracks, which will reduce the corrosion resistance to a certain extent.

When the concentration of zinc oxide is 8 g/L, the compactness and corrosion resistance of the coating are the best, and the thickness of the coating is positively correlated with the concentration of ZnO.

Too high concentration of ZnO reduces the performance of MAO coating.

The MAO coating prepared by adding ZnO has good corrosion resistance. Combined with organic coatings, it can be applied in corrosive marine environments, such as ship parts and hulls. To a certain extent, it can reduce the economic loss caused by corrosion.

The effect of ZnO on the corrosion resistance of MAO coating in electrolyte solution was studied systematically, and the conclusion was new to the common knowledge.

The unitized curtain wall system (UCWS), a symbol of modern architecture, is gaining popularity among prefabricated components. Previous studies have focused on both construction technology advances and material selection strategies to facilitate the UCWS. However, the topic of client satisfaction, which drives industry development by targeting clients' demands, has gone unnoticed. Therefore, the current study aims to investigate client satisfaction with UCWS products in Hong Kong by finding its influential factors.

A systematic review was employed to first identify the influential factors. A semi-structured interview was employed to validate the reliability of the extracted factors. The machine learning algorithm Extreme Gradient Boosting (XGBoost) and the Pearson correlation were then employed to rank the importance and correlation of factors based on the 1–5 Likert scale scores obtained through a questionnaire survey.

The findings revealed that “reduction in construction time” and “reduction in construction waste” are the most important factors and have a strong positive influence on client satisfaction.

Unlike previous studies, the present study focused on a novel research topic and introduces an objective analysis process using machine learning algorithms. The findings contribute to narrowing the knowledge gap regarding client preference for UCWS products from both individual and collaborative perspectives, providing decision-makers with an objective, quantitative and thorough reference before making investments in the curtain wall management development.

The purposes of this paper are to review the impact on food and nutrition security of several pandemic emergencies and the 2018 food price crisis from a global perspective, examine the Chinese experiences and lessons in ensuring food and nutrition security for its citizen and propose policy actions to prevent a global food and nutrition security crisis.

The authors utilize a noncomprehensive review of peer-reviewed and nonpeer-reviewed literature, as well as a case study approach.

Under the ongoing COVID-19, China's food and nutrition are relatively secure in short run largely due to governmental proactive policies but may face uncertainties in livestock production and imports of soybean in the medium and long terms. Given that the disease has spread to almost all countries in the world, global cooperation and coordination are needed to prevent systemic risks to global food and nutrition security.

The review and analysis of this paper will help policymakers in China and other countries to design strategies and actions to prevent food and nutrition security crisis under the ongoing COVID-19 emergency and other similar threats in the future.

This paper provides recommendations to prevent food and nutrition security crisis based on data, evidence and case studies.

The paper aims to explore how the undue state control leads to the weak stock market in China. It analyzes how the undue state control is exerted in some key areas in the Chinese stock market. This paper intends to expand the existing literature in the relationships among law, politics, and economy.

This paper mainly adopts the exploratory method to analyze the undue state influences. Under some circumstances, comparative study and historical explanation are also adopted.

The paper suggests that to create a strong stock market and facilitate the development of the listed companies and the whole economy, the state should first release its control on the stock market.

Various fields are contained in a stock market, in most of which the undue state control can be observed. In this paper, only some key ones are explored. Further research on other fields and if possible more first‐hand data are necessary.

This paper not only offers an answer to concerns on the various misconducts in the inefficient Chinese stock market and helps to realize the possible ways out of such dilemma, but also it offers implications for other emerging economies.

The on‐going debate on the role of common‐law versus civil‐law system in the capital market may have ignored the state involvement. This paper indicates that it is the undue state control rather than the legal system that leads to the weak stock market in China.