J.F. Flores, B. Valdez S., M. Schorr and J.J. Olaya
To investigate the protective properties of tantalum nitride (TaN) thin films deposited on to various steels immersed in a 3 per cent NaCl solution.
Abstract
Purpose
To investigate the protective properties of tantalum nitride (TaN) thin films deposited on to various steels immersed in a 3 per cent NaCl solution.
Design/methodology/approach
TaN thin films with a thickness of 250 nm were deposited on UNS G10180, UNS S30400 and UNS T11302 steels by means of magnetron sputtering technique. The electrochemical behaviour has been studied in 3 per cent NaCl solution using electrochemical impedance spectroscopy and potentiodynamic polarization. The crystalline structure of the films was investigated by X‐ray diffraction. Surface analysis of the corroded samples was performed using scanning electron microscopy and light optical microscopy. The electrochemical impedance spectra were analysed in the context of equivalent circuit models (ECs).
Findings
The ECs incorporate a charge transfer process representing the TaN film on UNS G10180 steel, two time constants for that deposited on UNS T11302 and diffusion behaviour for the TaN film on UNS S30400 steel. TaN films demonstrate their protection properties, which were evidenced by increase of the electrochemical properties compared with the substrate. The major corrosion damage of coatings is caused by defects, pores, droplets and pinholes that allow the electrolyte penetration through the films.
Practical implications
Corrosion protections of steels by TaN thin films.
Originality/value
The information related to corrosion behaviour of TaN films in a chloride solution is poor. This paper presents not only a completely electrochemical characterization, but also the surface analysis of the corroded samples.
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F. Escanes, C. D. Pérez‐Segarra and A. Oliva
This paper deals with a numerical simulation of the thermal andfluid‐dynamic behaviour of double‐pipe condensers and evaporators. Thegoverning equations of the fluid flow…
Abstract
This paper deals with a numerical simulation of the thermal and fluid‐dynamic behaviour of double‐pipe condensers and evaporators. The governing equations of the fluid flow (continuity, momentum and energy) in both the tube (evaporating or condensing flow) and the annulus (single‐phase flow), together with the energy equation in the tube wall, are solved iteratively in a segregated manner using a one‐dimensional, transient formulation, based on an implicit step by step numerical scheme in the zones with fluid flow (tube and annulus), and an implicit central difference numerical scheme in the tube wall, solved by means of the Tri‐Diagonal Matrix Algorithm (TDMA). This formulation requires the use of empirical information for the evaluation of convective heat transfer, shear stress and void fraction. Two criteria to calculate the location of the points of transition between single‐phase and two‐phase flow are tested. An analysis of the different parameters used in the discretization is made. Some illustrative results corresponding to the solution of a condenser and an evaporator using two different working fluids (R–12 and R–134a) are presented.
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Douglas Andrade, Dante Viana, Vera Ponte and Sylvia Domingos
This study analyzes earnings management among Brazilian public firms during the 2016 Presidential Impeachment.
Abstract
Purpose
This study analyzes earnings management among Brazilian public firms during the 2016 Presidential Impeachment.
Design/methodology/approach
The sample comprises, as a treatment group, 721 firm-quarter observations relating to Brazilian listed firms. It also considers a control group of listed firms from Mexico, which were not affected by the exogenous shock analyzed (i.e. the 2016 Presidential Impeachment in Brazil). The firms' quarterly financial data cover the period between 2013 and 2018.
Findings
Considering several proxies related to earnings management by accruals, the main findings suggest a negative relationship between the 2016 impeachment event and the level of discretionary accruals, suggesting that Brazilian firms tended to reduce their earnings management levels during the impeachment process. The results are robust whether the control group is considered or not.
Originality/value
This study brings new empirical evidence to the literature on accounting information quality about the role of the economic and political environment in earnings management, especially in weak institution countries characterized by institutional voids and higher levels of corruption.
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Tara D. Gray and Jamie Callahan
Skills Approach leadership development suggests individuals can develop the skills, abilities, and behaviors needed to lead. However, it can be difficult to understand and apply…
Abstract
Skills Approach leadership development suggests individuals can develop the skills, abilities, and behaviors needed to lead. However, it can be difficult to understand and apply these theoretical concepts. Movies provide a storytelling platform enabling learners to link theory to practice. This article uses 300 to explore skills-based leadership theories. 300 (2007) is an adaptation of Frank Miller’s novel depicting the Battle of Thermopylae (400 B.C.) between Greece and Persia. The movie tells the story of how King Leonidas led 300 Spartan warriors in battle against King Xerxes’ army in defense of Spartan land, values, and freedom. We provide background on Katz’s (1955) and Mumford, Zacaro, Harding, Jacobs, and Fleishman (2000) skills approaches. Then we describe how theoretical concepts associated with these approaches can be found in the movie. Finally, we provide suggestions for experiential learning activities which serve to help participants link and apply theory to practice.
Arash Arianpoor and Farideh Esmailzadeh Asali
The present study investigated the impact of earnings volatility and environmental uncertainty on accounting comparability in an emerging economy and the moderating role of…
Abstract
Purpose
The present study investigated the impact of earnings volatility and environmental uncertainty on accounting comparability in an emerging economy and the moderating role of COVID-19 pandemic for the companies listed on Tehran Stock Exchange (TSE).
Design/methodology/approach
The data about 181 companies during 2014–2021 were examined. In this study, accounting comparability was predicted for the firms' accounting systems and the coefficient estimates were calculated. The present study used the coefficient of variation of sales to capture sales volatility as the primary environmental uncertainty measure.
Findings
The results showed that both the earnings volatility and environmental uncertainty have a significant negative effect on accounting comparability, and that COVID-19 significantly increases the negative impact of earnings volatility and environmental uncertainty on accounting comparability. The hypothesis testing based on robust, GLS, GMM, GLM, OLS regressions and t+1 test confirmed these results.
Originality/value
The present study aimed to develop knowledge-providing benefits for companies about the accounting comparability and managing more efficient decisions. The present findings help investors to understand and evaluate the performance of firms more accurately especially in earnings volatility and environmental uncertainty conditions and in the wake of a pandemic crisis such as COVID-19.
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Frederick A. Rich, A. Mehran Shahhosseini, M. Affan Badar and Christopher J. Kluse
Reducing wear of undercarriage track propulsion systems used in heavy construction equipment decreases the maintenance costs and increases the equipment's life. Therefore…
Abstract
Purpose
Reducing wear of undercarriage track propulsion systems used in heavy construction equipment decreases the maintenance costs and increases the equipment's life. Therefore, understanding key factors that affect the wear rate is critical. This study is an attempt to predict undercarriage wear.
Design/methodology/approach
This research analyzes a sample of track-type dozers in the eastern half of North Carolina (NC), USA. Sand percentage in the soil, precipitation level, temperature, machine model, machine weight, elevation above sea level and work type code are considered as factors influencing the wear rate. Data are comprised of 353 machines. Machine model and work code data are categorical. Sand percentage, elevation, machine weight, average temperature and average precipitation are continuous. ANOVA is used to test the hypothesis.
Findings
The study found that only sand percentage has a significant impact on the wear rate. Consequently, a regression model is developed.
Research limitations/implications
The regression model can be used to predict undercarriage wear and bushing life in soils with different sand percentages. This is demonstrated using a hypothetical scenario for a construction company.
Originality/value
This work is useful in managing maintenance intervals of undercarriage tracks and in bidding construction jobs while predicting machine operating expense for each specific job site soil makeup.
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B.G. Lopez, S.B. Valdez, K.R. Zlatev, P.J. Flores, B.M. Carrillo and W.M. Schorr
Aggressive environments that enhance indoor corrosion in industrial plants decrease the yielding of electronic equipment, causing electrical failures. The purpose of the present…
Abstract
Purpose
Aggressive environments that enhance indoor corrosion in industrial plants decrease the yielding of electronic equipment, causing electrical failures. The purpose of the present paper is to evaluate corrosion rates in metals used in electronic devices as a function of temperature, humidity and the concentrations of some air pollutants in order to predict the optimal conditions preventing or minimizing corrosion.
Design/methodology/approach
Atmospheric pollutants mainly sulphur oxides, penetrating through small crevices and holes into electronic plants in combination with climatic factors such as humidity and heat, promote corrosion. The corrosion rate of the five most used metals in the electronics industry: carbon steel, copper, nickel, silver, and tin, were studied gravimetrically as a function of variations in humidity, temperature and air pollutant concentrations from 2003 to 2005. The samples were exposed in an instrumented boot to indoor conditions and gravimetric measurements were performed together with measurements of the above‐mentioned parameters. Mathematical simulation applying Math Lab software was carried out as well. The ternary diagrams for pollutants, temperature and relative humidity were applied as a useful tool to correlate these parameters in indoor conditions with the corrosion rate of metals applied in the electronics industry.
Findings
The obtained results have shown that the presence of even small concentrations of air pollutants promoted corrosion processes when time of wetness conditions were reached.
Practical implications
The study was carried out in order to minimize the corrosion losses of the electronic plants situated especially in Mexicali City located on a semi‐desert zone in the Northwest of Mexico.
Originality/value
This paper establishes the relationship of variations of pollutants concentration, temperature and the relative humidity with the corrosion rate of metals in indoor conditions in the electronics industry located in the semi‐arid zone of Mexicali. Design was characterized and simulated using the MathLab software.
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Rana I. Mahmood, Harraa S. Mohammed-Salih, Ata’a Ghazi, Hikmat J. Abdulbaqi and Jameel R. Al-Obaidi
In the developing field of nano-materials synthesis, copper oxide nanoparticles (NPs) are deemed to be one of the most significant transition metal oxides because of their…
Abstract
Purpose
In the developing field of nano-materials synthesis, copper oxide nanoparticles (NPs) are deemed to be one of the most significant transition metal oxides because of their intriguing characteristics. Its synthesis employing green chemistry principles has become a key source for next-generation antibiotics attributed to its features such as environmental friendliness, ease of use and affordability. Because they are more environmentally benign, plants have been employed to create metallic NPs. These plant extracts serve as capping, stabilising or hydrolytic agents and enable a regulated synthesis as well.
Design/methodology/approach
Organic chemical solvents are harmful and entail intense conditions during nanoparticle synthesis. The copper oxide NPs (CuO-NPs) synthesised by employing the green chemistry principle showed potential antitumor properties. Green synthesised CuO-NPs are regarded to be a strong contender for applications in the pharmacological, biomedical and environmental fields.
Findings
The aim of this study is to evaluate the anticancer potential of CuO-NPs plant extracts to isolate and characterise the active anticancer principles as well as to yield more effective, affordable, and safer cancer therapies.
Originality/value
This review article highlights the copper oxide nanoparticle's biomedical applications such as anticancer, antimicrobial, dental and drug delivery properties, future research perspectives and direction are also discussed.
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O.L. Vargas, S.B. Valdez, M.L. Veleva, K.R. Zlatev, W.M. Schorr and G.J. Terrazas
The purpose of this paper is to evaluate the corrosion of silver due to hydrogen sulphide pollutant in indoor conditions at a microelectronics plant located in Mexicali, Baja…
Abstract
Purpose
The purpose of this paper is to evaluate the corrosion of silver due to hydrogen sulphide pollutant in indoor conditions at a microelectronics plant located in Mexicali, Baja California, a semi‐arid zone in the northwest of Mexico.
Design/methodology/approach
Silver coupons and silver plated on to copper‐lead frames are exposed in the assembly process building of a microelectronics company during a period of 60 days and also in a sheltered test chamber that simulates indoor conditions with ambient concentrations of atmospheric pollutants, temperature and relative humidity (rH). Other exposures are made in the test chamber to study the corrosion behaviour of silver coupons over a duration of 24 months. The corrosion products were analysed using the Scanning Electron Microscope (SEM) and Energy Dispersive X‐ray Spectroscopy (EDS). Corrosion rates were measured by Quartz Crystal Microbalance (QCM) under laboratory‐controlled conditions.
Findings
The presence of silver sulphide corrosion products, dendrites and whiskers is observed on the exposed samples using SEM and EDS analysis.
Practical implications
The paper is designed to establish whether the company, where the exposure is taking place, constituted an indoor environment with outdoor hydrogen sulphide pollutant in sufficient concentration to induce silver corrosion.
Originality/value
The methodology used in this work can be applied to study the indoor corrosion behaviour of other metals, which will be of interest to the microelectronics industry.