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To evaluate the effect of synthesised calixarenes as new inhibitors on the corrosion of steel in HCl media at various temperatures.

Calixarenes have been synthesised and tested as corrosion inhibitors. Gravimetric technique and potentiodynamic polarisation and impedance spectroscopy methods were used.

Calixarenes exhibited a good inhibition. Their efficiency decreases slightly with temperature.

It was found that the inhibition efficiency increases with the concentration of inhibitors to reach 92 per cent at 10⁻⁴M.

The efficiency of calixarene derivatives increases with the concentration and falls slowly with temperature to attain 84 per cent at 353 K range. Calixarenes can be used in chemical cleaning and pickling processes.

The originality of this work is to find an inhibitor to give protection close to 100 per cent.

The privatization of State Owned Enterprises (SOE) has significant implications for SOE stakeholders. However, the effects on stakeholders will vary depending on characteristics of the privatization process and the structure of the SOE. This paper identifies privatization process characteristics of wealth creation and wealth distribution, and describes SOE structures on a continuum between government corporation and government agency. The privatization effectiveness for stakeholders is discussed and examples provided for each classification of privatization.

The purpose of this study is to ascertain whether nonlinearities could be present in electricity loads observed in subtropical environments, where none or little heating is required, and whether threshold autoregressive (TAR)-type regime switching models could be advantageous in the modeling of those loads.

The actual observed load of a Brazilian regional electricity distributor from January 2013 to August 2012 was modeled using a popularly employed ARMA model for reference, and smooth and non-smooth TAR transition (non-linear) models were used as non-linear regime switching models.

Evidence of nonlinearities were found in the load series, and evidence was also found on the intrinsic resistance of this type of models to structural breaks in the data. Additionally, to reacting well to asymmetries in the data, these models avoid the use of exogenous variables. Altogether, this could prove to be a definite advantage of the use of such model alternatives.

However, even if the present work may have been limited by the observation frequency of the available data, it appears TAR models appear to be a viable alternative to forecasting short-term electricity loads. Nonetheless, additional research is required to achieve a higher accuracy of forecast data.

If such models can be successfully used, it will be a great advantage for electricity generators, as the computational effort involved in the use of such models is not significantly larger than regular linear ones.

To our knowledge, this type of research has not yet been made with subtropical/tropical electricity load data.

The authors provide a comprehensive review of existing turnover studies in Spain. The literature review reveals that research on voluntary turnover is scarce, while other types of mobility, such as involuntary separations, downsizing, and planned turnover through contract date expiration, have received substantial attention. The authors identify the main institutional characteristics of Spain and explain why these may contribute to the low incidence of voluntary turnover. Specifically, the authors note that employment protection legislation, high unemployment, high unemployment insurance, centralized collective bargaining, the composition of the sector, high power distance, and in-group collectivism are important drivers of the patterns observed in existing turnover studies. The authors also explore how some of the mechanisms and processes exposed by key turnover theories may be applicable to the Spanish context. This chapter highlights the importance of paying attention to the role of the institutional and cultural context to understand different mobility patterns in the labor market. The authors also suggest several avenues for future research including the study of different turnover types, employer and employee outcomes, cultural variations, and employment practices.

This paper aims to provide an insight into recent advancements and developments of robotics for Natural Orifice Transluminal Surgery (NOTES) procedures.

Following an introduction that highlights the evolution from Minimally Invasive Surgery (MIS) to NOTES in the medical field, this paper reviews the main robotics systems that have been designed and implemented for MIS and NOTES, summarising their advantages and limitations and remarking the technological challenges and the requirements that still should be addressed and fulfilled.

The state-of-the-art presented in this paper shows that the majority of the platforms created for NOTES are laboratory prototypes, and their performances are still far from being optimal. New solutions are required to solve the problems confronted by the proposed systems such as the limited number of DOFs, the limited resolution, the optimal fixation and stiffening of the instruments for enabling stable and precise operation, the effective transmission of forces to the tip tools, the improvement of the force feedback feeling and the proper visualization and spatial orientation of the surgical field. Advances in robotics can contribute significantly to the development and future implementation of the NOTES procedure.

This paper highlights the current trends and challenges ahead in robotics applied to NOTES procedure.

The host–guest molecules are often used in various fields and applications. This paper aims to discuss the role of host–guest complexes in the textile industry, focusing on calixarenes as a potential adsorbent for hazardous dyes. The paper begins with an introduction to nanotechnology and its many uses, including textiles.

The risks associated with the utilisation of dyes and its adverse effects on the environment are then also highlighted. This paper also discusses the structure and characteristics of calixarenes and their potential use as an adsorbent to extract toxic metals from aqueous solutions. The paper also explains the molecular structure of calixarenes, especially the ability of its upper and lower rims, which can be altered to yield derivatives with various selectivities for diverse guest ions and small molecules. In addition, the application of various host–guest molecules in the textiles industry to extract dyes also had been discussed.

In conclusion, the paper highlights the essential in establishing a systematic review on the significance of selective adsorbents, such as calixarenes, to isolate particular targets from diverse matrices in the textile industry.

Only discussing several applications for several host–guest molecules.

The paper concisely describes various host–guest molecule applications in the textile industry, with each molecule being elaborated upon in detail.

Germany has become the most important destination country for young refugees in Europe (Destatis, 2021). Vocational education and training can make an important contribution to overcome educational barriers and gain participation in society (Will & Hohmut, 2020). Since 2015, rural regions have faced new challenges in establishing effective support systems for young apprentices with forced migration experience (Ohliger et al., 2017). The participatory LaeneAs research project seeks to identify educational barriers and to promote successful educational pathways for young refugees in vocational training. In four distinct rural areas in Germany, stakeholders in formal, non-formal, and informal learning environments and young refugees will be brought together in real-world laboratories. The authors aim to open space for a co-constructive knowledge production process between scientific and political stakeholders, educational practitioners, and refugee youth. Real-world laboratories are a socio-spatial methodology that combines research and a sustainable capacity building process. The lifeworld expertise will be used for a contextual condition analysis of structural, societal, and individual barriers to education as well as for practice transfer. Building on the discussion of the current state of research and the identification of significant gaps in the practice and research landscape, this essay will focus on the critical discussion of the methodological implementation of the study.

Fused deposition modelling (FDM) has gained popularity owing to its capability of producing complex and customized profiles at relatively low cost and in shorter periods. The study aims to extend the use of FDM printers for 3D printing of low melting point alloy (LMPA), which has applications in the electronics industry, rapid tooling, biomedical, etc.

Solder is the LMPA with alloy’s melting temperature (around 200°C) lower than the parent metals. The most common composition of the solder, which is widely used, is tin and lead. However, lead is a hazardous material having environmental and health deteriorating effects. Therefore, lead-free Sn89Bi10Cu non-eutectic alloy in the form of filament was used. The step-by-step method has been used to identify the process window for temperature, print speed, filament length (E) and layer height. The existing FDM printer was customized for the present work.

Analysis of infrared images has been done to understand discontinuity at a certain range of process parameters. The effect of printing parameters on inter-bonding, width and thickness of the layers has also been studied. The microstructure of the parent material and deposited bead has been observed. Conclusions were drawn out based on the results, and the scope for the future has been pointed out.

The experiments resulted in the process window identification of print speed, extrusion temperature, filament length and layer height of Sn89Bi10Cu which is not done previously.

The purpose of this paper is to explore the effects of low doses of caffeine (<3 mg/kg) on jumping performance using a meta-analysis.

The search for eligible studies was performed through six databases, with additional backward and forward citation tracking. A random-effects meta-analysis was performed to compare the effects of caffeine vs placebo on jump height. The methodological quality of the included studies was appraised using the physiotherapy evidence database checklist.

Eight studies were included in the review. They were classified as good or excellent methodological quality. The pooled number of participants across all studies was 203. Four studies provided caffeine in relative doses, ranging from 1 to 2 mg/kg. Four studies provided caffeine supplementation in absolute doses of 80, 150 or 200 mg. The meta-analysis found that caffeine ingestion increased vertical jump height (Cohen’s d: 0.21; 95% confidence interval: 0.10, 0.31; p < 0.001; +3.5%).

The present meta-analysis found that caffeine doses of ∼1 to 2 mg/kg enhance jumping height. The effects observed herein are similar to those with higher caffeine doses, which is relevant as low caffeine doses produce minimal side effects. For most individuals, a caffeine dose of ∼1 to 2 mg/kg is equivalent to an amount of caffeine in an energy drink, one to two cups of coffee, one to two pieces of caffeinated chewing gum or several cups of green tea.

Caffeine is a popular ergogenic aid, but its effects on swimming performance are not yet fully clear. Therefore, the purpose of this paper is to examine the effects of caffeine on swimming performance.

Crossover placebo-controlled studies that explored the effects of caffeine on swimming performance were included. Six databases were searched to find relevant studies with additional forward and backward citation tracking. The data were pooled in a random-effects meta-analysis.

Eight studies were included in the review. The main meta-analysis showed a significant ergogenic effect of caffeine ingestion on swimming performance (Cohen’s d: –0.20; 95% confidence interval: −0.32, −0.08; p = 0.0008; –1.7%). In the analysis for short-distance swimming events, caffeine ingestion had a significant ergogenic effect on swimming performance (Cohen’s d: –0.14; 95% confidence interval: –0.27, −0.01; p = 0.03; −1.4%). An ergogenic effect of caffeine was also found in the analysis for moderate-to-long swimming distance events (Cohen’s d: –0.36; 95% confidence interval: −0.67, −0.05; p = 0.02; −2.2%).

The present meta-analysis found that caffeine ingestion decreases the time needed to complete a given swimming event. While these ergogenic effects may be classified as small, they are likely important in swimming, where narrow margins commonly determine placings.