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Purpose – The aim of this study is to determine the differences in the antimicrobial activity of katuk leaf (Sauropus androgynus (L.) Merr) against Escherichia coli.

Design/Methodology/Approach – The method used in this study was experimental posttest using a control group design. Analysis of the effect of katuk leaf was performed in the dilution method with 20%, 40%, 60%, 80%, and 100% concentration. The data were analyzed using one-way ANOVA test (α = 0.05) and was then tested using the least significant difference (LSD) test.

Findings – Bacterial colony counting that used total plant count found the average of E. coli amount at 20% of concentration (526.820 CFU/ml), 40% of concentration (449.380 CFU/ml), concentration of 60% (255.710 CFU/ml), concentration of 80% (194.110 CFU/ml), and at concentration 100% (168.600 CFU/ml). This study concluded that the katuk leaf extract at 20%, 40%, 60%, 80%, and 100% of concentration had antimicroba effect with significant influence. The 100% of concentration had the most significant effect compared with the other concentrations.

Research Limitations/Implications – Katuk leaf could be used as one of the alternative herbal choices that has a compound antimicrobial effect.

Originality/Value – This study increases the theoretical understanding of the difference of antimicrobial effectivity of katuk leaf extract (S. Androgynus (L.) Merr.) concentration against E. coli

This paper has a dual purpose: to produce a clear panorama of microfactors behind the implementation of environmental, social and governance (ESG) in emergent economies, and to identify long-term versus short-term implications of ESG and its impacts on sustainable transformation. In particular, the paper investigates the moderating role of ownership concentration on ESG performance and firm value relationship in Southeast Asia during 2010–2022 and COVID-19 period 2020–2022.

By adopting stakeholder and agency theory lenses, this study analyzes 591 nonfinancial listed companies in Southeast Asia from 2010 to 2022 with 2,673 firm-year observations. Data has been collected from Refinitiv and companies' annual reports. Ordinary least squares (OLS) and two-stage least squares (2SLS) estimators are main strategies.

During 2010–2022, the links between ESG performances and firm value are negative. Ownership concentration negatively moderates the nexus between governance pillar and firm value in both short and long run. In COVID-19, ownership concentration also plays an antagonistic moderating role in ESG combined score-firm value association. The results show a crucial role of blockholders in Southeast Asian firms and their strong support to ESG in conquering crisis period, suggesting that managers develop balancing mechanisms in making ESG-related decisions; policymakers and regulators improve effective control instruments with strong legal systems and enhanced law enforcement to protect minority shareholders.

This is the first study to test the connection between ESG performance, ownership concentration and firm value in Southeast Asia that has: (1) utilized different proxies of firm value and ownership concentration in robustness tests, (2) controlled heteroskedasticity defects, (3) eliminated companies in the Banking and Finance sector from the sample to avoid distorting the conclusions and (4) empirically verified the driven role of governance pillar in ESG performance and ownership concentration reversely moderated the impact of governance pillar on firm value.

Determining the variation law of the oxygen concentration in the ullage space of the fuel tank is the key to the design of the inert system. Among various factors affecting the oxygen concentration in the ullage space of the fuel tank, the temperature difference between day and night shows particular importance while relevant analysis and calculation are scarce.

This study establishes a theoretical simulation model of the central wing fuel tank of an aircraft according to the relevant provisions of day-night temperature variation in FAR25 airworthiness regulations, verifies the model with the existing experimental data and discusses the corresponding relationship between the oxygen concentration in the ullage space of the fuel tank and the day-night temperature difference. The influence of day and night temperature difference, fuel type, fuel load rate, initial oxygen concentration, dissolved oxygen evolution and other factors on the oxygen concentration in the ullage space of the fuel tank were analyzed, and the limit of initial oxygen concentration of the fuel tank before the shutdown at night meeting the requirements of the airworthiness provisions was proposed.

The results show that the temperature difference between day and night, fuel load rate, initial oxygen concentration and other factors have different effects on the oxygen concentration in the ullage space of fuel tank. The initial oxygen concentration limit before shutdown shall be 2% below the 12% oxygen concentration stipulated by FAA.

The research results in this paper will be of good reference value to the design of the inert system and the calculation of the flammability exposure evaluation time. This paper aims to be good reference of the design of the inert system and the calculation of the flammability exposure evaluation time.

The research results of this paper can provide practical guidance for the current civil airworthiness certification work.

We conducted this study to examine the relationship between revenue concentration and a firm's financial leverage. We aimed to analyze whether revenue concentration influences a firm's capital structure decisions and whether this relationship is driven by customer-specific investments or the direct effect of revenue concentration itself. Additionally, we investigated the role of asset redeployability in mediating or moderating the relationship between revenue concentration and financial leverage.

The paper investigates the relationship between revenue concentration and a firm's financial leverage. The results indicate a negative association between revenue concentration and financial leverage. This finding holds across various regression models and is statistically significant. Furthermore, the paper explores the potential role of asset redeployability in explaining the relationship between revenue concentration and financial leverage. The results indicate that even after controlling for asset redeployability, the negative relationship between revenue concentration and leverage remains significant, suggesting that revenue concentration affects capital structure decisions independently of the risks associated with relationship-specific investments. Robustness tests are conducted using a three-stage least squares approach to account for the simultaneity between revenue concentration, asset redeployability and capital structure.

Our findings demonstrate that revenue concentration is negatively associated with financial leverage, even after accounting for asset redeployability. This suggests that revenue concentration affects capital structure decisions independently of the risks associated with customer-specific investments. Furthermore, we performed robustness tests to address potential simultaneity issues between revenue concentration, asset redeployability and capital structure.

The study relies on available data sources, which may have inherent limitations in terms of accuracy, completeness or consistency. The quality of the data used in the analysis could impact the robustness of the findings. Time Period: The study focuses on more recent years, which might limit the ability to compare the findings with studies conducted over different time periods. Historical trends or structural changes that could impact the relationship between revenue concentration and financial leverage might not be fully captured.

Firms with higher revenue concentration tend to have lower financial leverage. Recent years show a negative relationship between profitability and market leverage compared to earlier periods. Revenue concentration has a distinct effect on financial leverage, not fully explained by risks from relationship-specific investments or asset redeployability. Insights for firms in managing capital structure decisions, considering revenue concentration and its implications for leverage.

This research is one of the first papers that investigates the impact of revenue concentration on the capital structure choices of firms. By exploring the relationship between revenue concentration and financial leverage, the study contributes to the existing literature by shedding light on an underexplored area. Thus, this study adds originality to the field by addressing a research gap and contributing to the understanding of the relationship between revenue concentration and capital structure choices.

Based on resource dependence theory (RDT) and transaction cost theory (TCT), we aim to investigate the relationship between supply chain concentration and firm performance. Based on the resource-based perspective, we further investigate the moderating effect of marketing and operational capabilities on the relationship between supply chain concentration and firm performance.

Based on data from 2,082 firms with 8,371 observations from 2008 to 2020 in China, we use stochastic frontier analysis to calculate marketing capability and operational capability and use multinational regressions to test our research model.

We find a U-shaped relationship between supplier concentration and firm performance; there is also a U-shaped relationship between customer concentration and firm performance. In addition, the relationship between supplier concentration and firm financial performance is strengthened by the firm’s marketing capability, and the relationship between customer concentration and firm financial performance is weakened by the firm’s operational capability.

Drawing from RDT and TCT, this study extends the research on the impact of supply chain concentration on firm performance. The study finds that supply chain concentration and firm performance have a nonlinear relationship, and it is further moderated by marketing capability and operational capability, providing insights for managers.

The purpose of this paper is to investigate the effect of NaCl solution with different concentrations on impact-sliding fretting corrosion behavior of Inconel 690TT steam generator heat transfer tubes.

The optical 3D profiler was used to measure the wear profile and calculated the wear volume. Corrosion behavior was studied using open circuit potential monitoring and potentiodynamic polarization testing. The morphologies and elemental distributions of wear scars were analyzed using scanning electron microscopy and energy-dispersive spectroscopy. The synergism of wear and corrosion was analyzed according to the ASTM G119 standard.

The corrosion tendency reflected by OCP and the corrosion current calculated by Tafel both increased with the increase of NaCl concentration. The total volume loss of the material increased with concentration, and it was known from the synergism that the volume loss caused by corrosion-enhanced wear accounted for the largest proportion, while the wear-enhanced corrosion also made a greater contribution to volume loss than tangential fretting corrosion. Through the analysis of the material morphologies and synergism of wear and corrosion, the damage mechanism was elucidated.

The research findings can provide reference for impact-sliding fretting corrosion behavior of Inconel 690TT heat transfer tubes in NaCl solution with different concentrations.

University students’ lecture theatre concentration levels are significantly related to indoor environmental quality (IEQ). The purpose of this study is to investigate the relationship between indoor environmental quality (IEQ) and the self-reported concentration levels of university students during the winter at University College London (UCL), UK.

A questionnaire survey and physical measurements were used to assess the IEQ factors affecting students’ concentration levels.

The lecture theatre design factor was the most significant factor influencing students’ concentration levels, and the facility environment was more important than the thermal environment, indoor air quality, and acoustic environment in influencing students’ concentration levels in this winter investigation at UCL, UK. Additionally, students prefer a colder thermal environment. The concentration level of students was positively correlated with the indoor air quality and negatively correlated with the acoustic environment.

Based on model application, this research could provide lecture theatre IEQ design. This research additionally provides an acceptable indoor thermal environment temperature range based on a large sample, which can be used to calibrate a student performance benchmark.

As this study evaluates the IEQ factors that influence the concentration levels of university students, interior designers and engineers should consider the rational layout of these factors. Therefore, this study may provide a reference for the interior environmental design of lecture theatres in educational buildings.

The purpose of this study is to improve the performance of hollow fiber membrane and improve the separation efficiency.

By establishing a mathematical model of hollow fiber membrane gas separation, the influences of parameters such as pressure difference between the inside and outside of the filament, initial oxygen concentration of intake air, intake air flow rate and back pressure outside the filament on the polarization coefficient were analyzed, so as to explore the degree of influence of operating parameters on the concentration polarization, and put forward a technical scheme to reduce the concentration polarization.

Factors such as pressure difference between the inside and outside of the filament, initial oxygen concentration of intake air, intake air flow rate and back pressure outside the filament have a certain effect on the polarization coefficient. Among them, the polarization coefficient is positively correlated with pressure difference inside and outside the filament, initial oxygen concentration of intake air and back pressure outside the filament, and is negatively correlated with intake air flow.

Negative pressure suction on the permeation side can be used to increase the membrane permeation flow rate and reduce the concentration polarization.

The influence of concentration polarization on membrane performance is reduced by controlling various factors.

The present study aims at shedding some light on the serious effect of insecure pesticides to the surface ozone as a secondary pollutant resulting from some photochemical reactions during the sunny days. The temporal variation in O₃ concentrations due to pesticide spray, the corresponding temperature and relative humidity have been monitored and discussed. The air quality index (AQI) for the maximum concentrations of O₃ within each day of study has also been deduced. The obtained results illustrated that O₃ concentrations had been increased after pesticide spray with different values from hour to hour and then began to decay after one day or more according to its concentrations. The second day had the highest concentrations of the O₃ including the maximum concentration, which was recorded at hour 14 local time. Furthermore, most of AQI values were restricted between harmful and very harmful index during the second days and only the third day of the first experiment. Moreover, temperature and relative humidity have significantly influenced ozone concentrations with positive and negative correlation coefficients, respectively.

The purpose of this research is to study the effect of softener treatment on plain jersey fabrics with properties made of cotton and spandex yarn.

Samples with 100 percent cotton yarns, spandex yarns in alternating courses (half plating) and spandex yarns in every courses (full plating) were produced on a circular knitting machine where the two latter cases were produced at five different levels of spandex extension. After the dyeing process, fabrics were treated with fabric softener using two softener types (cationic and silicon) and all type two concentrations (3 percent, 6 percent) to evaluate the most appropriate softener type and concentration on fabric friction force, sewing needle penetration force and weight loss percent under different levels of spandex extension.

Results showed that silicon softener treatment results in high decreases in fabric sewing needle penetrating force, friction force and while treatment with cationic softener results in high decreases in weight loss percent for 100 percent cotton, half and full plating fabrics.

There is a growing need to study the effect of softeners when spandex yarns are used in the production of knitted fabric which results in high increase of stitch density. This research compares the effects of two different softener types at different concentrations on the properties of both plain jersey fabric produced from 100 percent cotton yarns and from cotton/spandex yarns with different stitch density.