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This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys.

These phosphate coatings were obtained by immersing magnesium alloys in phosphate baths with HMTA. The morphology and composition of the phosphate coatings were investigated via scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction.

The phosphate coatings were mainly composed of CaHPO₄·2H₂O. The HMTA concentration in the phosphate bath influenced the crystallization and corrosion resistance of the phosphate coating.

The polarization curve shows that the anti-corrosion qualities of the phosphate coating were optimal when the HMTA concentration was 1.0 g/L in the phosphate bath. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical impedances increased gradually when the HMTA concentration varied from 1.0 to 3.0 g/L.

Drawing on the conservation of resources theory, the present research paper examines the moderating role of leaders' Machiavellianism in the relationships between the desire for promotion, workplace anxiety and exploitative leadership.

The authors collected matched time-lagged data from part-time MBA students and their subordinates. The subordinate questionnaires were paired and coded by the researchers and then directly distributed and instructed to be filled out, which would not be known to the MBA students. The final sample size came to 370 leader-subordinate dyads. The data were analyzed using SPSS 24 and Mplus 7.0.

Leaders' desire for promotion is positively related to exploitative leadership via workplace anxiety. Furthermore, this mediating effect is significant when Machiavellianism is high, but not when Machiavellianism is low.

For business ethics scholars and practitioners, this study points out that leaders with a desire for promotion can produce workplace anxiety, lead to subordinates' perception of exploitative leadership and how this process varies by key personality trait—Machiavellianism.

This research aims to present the results of a study that operationalizes the construct of perceived work identity deprivation (PWID) and examines its validity.

The authors adopted a mixed method design in this study where a Likert-type scale to measure PWID was developed based on the interviews of 40 workers and the questionnaires of 625 participants successively. Later, the generalizability of the scale was tested through quantitative data from 412 workers. Finally, validity analysis was conducted based on 380 usable questionnaires. Data were analyzed using IBM SPSS 24 and Mplus 7.0.

The findings of the study indicate that the reliability measures, exploratory factor analyses, confirmatory factor analysis and subsequent convergent and discriminant validity tests support the PWID scale. The nomological validity of PWID is also presented, which demonstrates its predictive validity.

Despite highlighting the importance of work identity, prior research lacked to provide empirical foundations to understand this perception. This study fills this gap in the literature by providing a measure of PWID, distinguishing it from similar constructs and establishing convergent, discriminant and nomological validity. Moreover, by extending the range of theoretical and measurable deprivation of work identity, the authors hope to allow research to take into account a more complete picture of it. PWID scale can be used to develop more relevant suppression plans.

Purpose — To develop methodologies to evaluate search engines according to an individual's preference in an easy and reliable manner, and to formulate user-oriented metrics to compare freshness and duplication in search results.

Design/methodology/approach — A personalised evaluation model for comparing search engines is designed as a hierarchy of weighted parameters. These commonly found search engine features and performance measures are given quantitative and qualitative ratings by an individual user. Furthermore, three performance measurement metrics are formulated and presented as histograms for visual inspection. A methodology is introduced to quantitatively compare and recognise the different histogram patterns within the context of search engine performance.

Findings — Precision and recall are the fundamental measures used in many search engine evaluations due to their simplicity, fairness and reliability. Most recent evaluation models are user oriented and focus on relevance issues. Identifiable statistical patterns are found in performance measures of search engines.

Research limitations/implications — The specific parameters used in the evaluation model could be further refined. A larger scale user study would confirm the validity and usefulness of the model. The three performance measures presented give a reasonably informative overview of the characteristics of a search engine. However, additional performance parameters and their resulting statistical patterns would make the methodology more valuable to the users.

Practical implications — The easy-to-use personalised search engine evaluation model can be tailored to an individual's preference and needs simply by changing the weights and modifying the features considered. A user is able to get an idea of the characteristics of a search engine quickly using the quantitative measure of histogram patterns that represent the search performance metrics introduced.

Originality/value — The presented work is considered original as one of the first search engine evaluation models that can be personalised. This enables a Web searcher to choose an appropriate search engine for his/her needs and hence finding the right information in the shortest time with the least effort.

This paper aims to propose a novel system design and control algorithm of lower limb exoskeleton, which provides walking assistance and load sharing for the wearer.

In this paper, the valve-controlled asymmetrical hydraulic cylinder is selected for driving the hip and knee joint of exoskeleton. Pressure shoe is developed that purpose on detecting changes in plantar force, and a fuzzy recognition algorithm using plantar pressure is proposed. Dynamic model of the exoskeleton is established, and the sliding mode control is developed to implement the position tracking of exoskeleton. A series of prototype experiments including benchtop test, full assistance, partial assistance and loaded walking experiments are set up to verify the tracking performance and power-assisted effect of the proposed exoskeleton.

The control performance of PID control and sliding mode control are compared. The experimental data shows the tracking trajectories and tracking errors of sliding mode control and demonstrate its good robustness to nonlinearities. sEMG of the gastrocnemius muscle tends to be significantly weakened during assisted walking.

In this paper, a structure that the knee joint and hip joint driven by the valve-controlled asymmetrical cylinder is used to provide walking assistance for the wearer. The sliding mode control is proposed to deal with the nonlinearities during joint rotation and fluids. It shows great robustness and frequency adaptability through experiments under different motion frequencies and assistance modes. The design and control method of exoskeleton is a good attempt, which takes positive impacts on the productivity or quality of the life of wearers.

This paper aims to discuss major influencing factors causing users’ mobile social media fatigue and divides them into three hierarchies, including causal factors, intermediary factors and outcome factors. The study also sorts out connections between different levels of factors, thus providing effective guidance for the sustained development of social media.

Based on the grounded theory and by collecting data through in-depth interviews, the authors use open coding, axial coding and selective coding to analyze major influencing factors of users’ mobile social media fatigue, build a model using the software NVivo 11, organize and analyze mobile social media fatigue behavior and identify the relationships by combining the interpretive structural model and explore connections among the factors.

The influencing factors of mobile social media fatigue behavior conform with the stressors-strains-outcomes (SSO) theoretical framework, where stressors (S) include the five factors of fear of missing out, perceived overload, compulsive use, time cost and privacy concerns; strains (S) include the five factors of a low sense of achievement, emotional anxiety, reduced interest, social concerns and emotional exhaustion; outcomes (O) include the six factors of neglect behavior, diving behavior, avoidance behavior, tolerance behavior, withdrawal behavior and substitution behavior.

It focuses on the discussion of the interactions between users’ stressors, strains and outcomes without fully considering the impact of social environment and educational background on social media fatigue behavior. This study only focuses on one social media platform in the Chinese context, namely, WeChat. We reply on the qualitative research method to construct the relationships between social media fatigue factors because we were mainly interested in how users would respond psychologically and emotionally to social media fatigue behavior.

The study has extended the application of the SSO theory. Additionally, the research method and model used in this paper may serve as guidelines to other interested scholars who intend to explore relevant variables and conduct further research on the influencing factors of social media fatigue. In analyzing the causality of social media fatigue, the study has integrated the intermediary factor strain to display users’ strains from social media stress with a more detailed path discussion on the causality of social media fatigue, which has not received broad attention in previous research literature on social networking services users’ use.

In this study, text data are collected in a diversity of forms combined, allowing respondents to answer questions without being limited by the questions in the questionnaire, which helped us to identify new variables of social media fatigue. As a result, we were able to dig out the fundamental causes of social media fatigue and potential connections between the factors. Relevant scholars, users and businesses may analyze, manage and forecast users’ social media fatigue behavior by analyzing the type of social media stress and users’ state, providing guidance for the proposal of corresponding management strategies.

Most relevant studies focus on the sustained use of social media, and there is a scarcity of studies on social media fatigue in China. There is very limited research that conducts model analysis of social media fatigue through the integration of stressors, strains and outcomes.

This study aims to systematically investigate the tribological behaviors of metal and polyethylene using lubricants composed of four synovial fluid (SF) components. In addition, the changes in protein conformation during wear were analyzed to establish the correlation between protein conformation and tribological properties.

A pin-on-disk tester with multidirectional sliding motion was used for tribological properties observation between metal and polyethylene pairs. Simulated SFs with four main constituents were used as the testing lubricants. Differential scanning calorimetry and Raman were used to characterize the changes in protein conformation during wear.

The coupling of lipids and hyaluronic acid further suppressed protein denaturation. The protein structures of the adsorption film and the ensnared protein chains in the friction zone were maintained to a certain extent, thus improving the friction and wear of polyethylene.

These findings established the correlation between protein conformation and friction and wear, promoting the understanding of the lubrication mechanism of artificial joints.

The purpose of this paper is to present an overview of the evolution of organic solderability preservatives (OSP) technology from a temporary anti‐tarnish to an approved process for the lead‐free assembly of high‐reliability printed circuit boards (PCBs).

As this is an informational paper, the main approach was to compare and contrast various types of OSP molecules and their fitness for use.

The active ingredient of an OSP is one of the most important ingredients that can help to improve the heat resistance, which becomes much more important in conjunction with lead‐free solder. The latest OSP shows excellent stability, even at more than the peak reflow temperatures used with lead‐free solders. The success of any OSP process is highly correlated to process control and maintenance and OSP formulations are not created equal. The thickness of the film is only one difference. However, the key differentiators for OSP coatings are the overall ability of the organic film to resist oxygen penetration and humidity; and withstand the higher temperatures of lead‐free assembly. The author suggests that original equipment manufacturer (OEMs), contract manufacturers and PCB fabricators perform testing and qualification of OSPs using industry‐accepted reliability and solderability testing methods.

This work represents the author's extensive experience with OSP technology, as well as the results of a collective collaboration with Shikoku Chemical Corporation. The findings represent reliability and solderability testing carried out in various manufacturing sites including cooperation with certain OEMs that are users of circuits fabricated with OSP technology.

This paper details how critical advances in OSP technology have enabled improvements in solderability and reliability over earlier commercial generations and have further enhanced the solderability of lead‐free assemblies.