The intermittent flow cold storage heat exchanger is one of the most important components of the pulse tube expansion refrigerator based on the reverse Brayton cycle. In the experimental system, the volume and heat transfer of the helical tube play a decisive role in the stable operation of the whole experimental system. However, there are few studies on heat transfer in a helical tube under helium working medium and intermittent flow conditions. In this paper, a process and method for calculating the volume of a helical tube are proposed based on the gas vessel dynamics model. Subsequently, a three-dimensional simulation model of the helical tube was established to analyze the heat transfer process of cryogenic helium within the tube. The simulations revealed that the temperature of helium in the tube decreases to the wall temperature and does not change when the helical angle exceeds 720°. Moreover, within the mass flow rate range of 1.6 g/s to 3.2 g/s, an increase in the mass flow rate was found to enhance the heat transfer performance of the helical tube. This study provides a reference for the selection and application of a helical tube under intermittent flow conditions and also contributes to the experimental research of inter-wall heat exchanger and pulse tube expansion refrigerators.

Broad-spectrum antibiotics, such as tetracyclines, are used to treat and manage a range of infectious disorders. Since the kidneys are the primary organs responsible for excreting tetracyclines, clinicians should refrain from prescribing them to patients who have renal failure. Tetracyclines are one of the clinical waste products of today. One of the biggest problems in the field of pollution of the environment today is the persistence of different pharmaceutical residues, drug residues, pesticides, and metal ion species of the new-generation pollutants in surfaces and groundwater. In the present work, carboxymethyl cellulose (CMC)-CuO nanoparticles (CMC-CuO NPs) were synthesized using CuO NPs within different amounts of CMC (0.5, 1.0, 1.5 and 2.0 g) at 85 °C. The synthesized nanoparticles were characterized by XRD, FT IR, SEM, and TG-DTA analysis. According to XRD and SEM, the crystallize size and morphology influenced the dosage of CMC. FT-IR analysis confines the layer of CMC to the CuO nanoparticle surface. TG-DTA results indicated that the CMC content of CMC-CuO NPs was between the range of 69% and 75% by weight. The effects of some parameters such as initial concentration, pH, adsorbent dosage, and contact time on the adsorption of tetracycline from aqueous model solutions on CMC-CuO NPs were investigated with batch studies. It was found that the removal of tetracycline was obtained about 80% with optimized parameters of 10 mg/L concentration, 180 min contact time, 5 pH, and 0.3 g/25 mL dose. The synthesized CMC-CuO NPs nanocomposite may be a promising material for the removal of tetracycline in environmental pollution and toxicology.

Recently, Agile project management has received significant academic and industry attention from due to its advantages, such as decreased costs and time, increased effectiveness, and adaptiveness towards challenging business environments. This study primarily aims to investigate the relationship between the success factors and Agile project management methodology adoption and examine the moderating effect of perceived compatibility. The technology-organization-environment (TOE) framework and technology acceptance theories (UTAUT, IDT, and TAM) were applied as the theoretical foundation of the current study. A survey questionnaire method was employed to achieve the study objectives, while quantitative primary data were gathered using a carefully designed methodological approach focusing on Omani oil and gas industry. The PLS-SEM technique and SmartPLS software were used for hypotheses testing and data analysis. Resultantly, readiness, technology utilization, organizational factors, and perceived compatibility were the significant factors that promoted Agile methodology adoption in the oil and gas industry. Perceived compatibility moderated the relationship between success factors and Agile methodology. The findings suggested that people, technology, and organizational factors facilitate the Agile methodology under the technology acceptance theories and frameworks. Relevant stakeholders should adopt the study outcomes to improve Agile methodology adoption.

This work presents the evaluation of iron oxide nanoparticles obtained from the aqueous extract of Eucalyptus grandis. Twenty-three experiments were carried out where the synthesis of nanoparticles was performed by using the aqueous extract together with salts of iron (II) chloride tetrahydrate and iron (III) chloride hexahydrate. A characterization was carried out by IR, TEM and BET, where bands were presented at 3,440.77, 1,559.26 and 445.31 cm⁻¹, indicating the presence of iron oxide nanoparticles. A relatively high monodispersity was evidenced with particles around 9 nm. By means of BET analysis it was found to present a surface area of 131.897 m²/g. Obtaining nanoparticles by this green method presents yield values of 98%, with application in nanotechnology, biomedicine, environmental treatment, among others, making them highly versatile and their production cost is relatively low.

The business world is currently undergoing a significant shift towards sustainability and intelligent automation, which presents both promising prospects and formidable hurdles for business owners. The increasing demand for sustainable goods and services, driven by pressing social and environmental issues, opens doors for entrepreneurs to establish companies that address these concerns. Moreover, automation and technological advancements have revolutionized the operational landscape of firms, providing entrepreneurs with novel opportunities to enhance efficiency and foster creativity. However, thriving in this dynamic environment necessitates a fresh skill set and innovative approaches. Entrepreneurs must actively acquire the requisite technological expertise to leverage the potential of intelligent automation while navigating the intricate legislative and social frameworks surrounding sustainability. Furthermore, they must demonstrate agility and adaptability, adept at pivoting strategies and offerings to align with the evolving business panorama. This study’s exploration of the intersection of automation and entrepreneurship resonates deeply with the principles of sustainability. By dissecting the challenges and strategies entrepreneurs use to embrace automation, the research contributes valuable insights to the ongoing discourse on feasible business practices within the context of burgeoning sustainability. The findings will assist policymakers by providing useful information to cultivate an environment conducive to sustainable, technology-based entrepreneurship.

Companies are impacted by toxic leadership phenomena, resulting in many dissatisfied employees, low morale, and reduced progress. The fundamental mismatch between good leadership and harmful actions of toxic leaders is the primary cause of the problem. Toxic leadership can also be developed from narcissistic behavior of considering personal interests or using humiliation to maintain power. In this context, employees are negatively affected, resulting in higher stress levels, poorer job satisfaction, and a significant decrease in trust. Therefore, this research aims to explore the impact of toxic leadership and other factors on companies. The sample consists of 187 senior employees in the accounting department who worked in manufacturing companies. The results showed that toxic leadership influences role stress, while role stress affects emotional exhaustion and reactive work behavior. Moreover, future research should be conducted using other samples such as hospital employees or pay attention to other aspects related to role stress.