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Article

14 April 2025

Efficient Extracellular Production of Phospholipase D in Escherichia coli via Genetic and Process Engineering Modification

Phospholipase D (PLD) is the key enzyme in the catalytic production of rare phospholipids including phosphatidylserine. It was considered a promising method via genetic manipulation for the heterologous production of PLD in the model chassis. Few works focused on the extracellular production of PLD in engineered microbes. Herein, genetic and process engineering modification strategies were developed to achieve secretory production of PLD in Escherichia coli. The N-terminal fusion secretion signal peptide OmpA and the plasmid pBAD-gⅢC with pBAD promoter were proven to be the most effective in promoting the secretory production of PLD. Given the limitation of the cell membrane, the regulation of the key protein expression in the cell membrane as well as the addition of surfactants, were explored to accelerate the secretory production of PLD further. It was indicated that adding 0.5% (w/v) Triton X-100 was more conducive to producing PLD. Finally, fed-batch fermentation was conducted, and the maximum extracellular PLD activity achieved was 33.25 U/mL, which was the highest level reported so far. Our work demonstrated the effectiveness of genetic and process engineering strategies for the secretory production of PLD in E. coli, which provided an alternative platform for the industrial production of PLD.

Keywords: Phospholipase D; Secretory production; Signal peptide; Surfactant
Synth. Biol. Eng.
2025,
3
(2), 10006; 
Open Access

Article

11 April 2025

Virtual Spaces of Islamic Preaching: Digital Majelis Taklim and the Changing Role of Women in Indonesia

This study investigates the changing role of women in digital da’wah and the digital transformation of Majelis Taklim (Islamic study groups) in Indonesia. As digital platforms like YouTube, Instagram, WhatsApp, Telegram, and TikTok become more widely used, this study explores how women negotiate power, shape religious discourse, and interact with audiences online. The study employs a qualitative approach using digital ethnography and critical discourse analysis (CDA) to examine the interactions and narratives shaping women’s roles in digital da’wah. Data were collected through digital observations, in-depth interviews with female preachers (ustazah), moderators, and active participants, and content analysis of Majelis Taklim sessions on social media. The study applies Fairclough’s CDA to analyze power relations within religious discourse and Van Dijk’s Critical Discourse Studies (CDS) to examine how digital da’wah reconstructs female religious authority. The results reveal a shift in women’s roles from passive participants to active producers of religious discourse. While digitalization provides broader access and participation opportunities, female preachers still face challenges in establishing religious authority, particularly in male-dominated Islamic discourses. The study finds that key themes in women-led da’wah include Islamic parenting, hijrah (religious transformation), Islamic economy, and women’s roles in Islam. Digital platforms do provide female scholars more prominence, but they also perpetuate patriarchal interpretations of religious norms. By combining digital ethnography, critical discourse analysis, and religious studies, this work adds to the conversation on Islam, gender, and digital religious practices. It shows how digital media influences women’s involvement in da’wah by presenting opportunities and limitations. Unlike other studies concentrating on male religious authority in digital da’wah, this research offers a thorough, empirical, and theoretical examination of how women manage religious influence and legitimacy online. The findings have implications for developing inclusive, digital-based Islamic education and policymaking on religious discourse in the digital era.

Keywords: Digital da’wah; Majelis Taklim; Islamic preaching; Female religious authority; Digital ethnography; Discourse analysis
Nat. Anthropol.
2025,
3
(2), 10005; 
Open Access

Article

08 April 2025

Research on the Logic of Mobile Governance from the Perspective of Path Dependency: A Case Study of the Implementation of the “Coal-to-Gas” Policy in Rural Areas of Handan

Mobile governance, a commonly used governance approach in China, has always been controversial. Behind the persistence of mobile governance lies the underlying governance logic. This paper takes the implementation of the “coal-to-gas” policy in rural areas of Handan as a case study to analyze the path-dependent logic inherent in mobile governance. The paper argues that mobile governance’s selection path embodies path dependency characteristics, including three paths: conformist path dependency, policy-based path dependency, and demand-based path dependency. Mobile governance can be regulated through three paths: formulating a comprehensive list of rights and responsibilities for grassroots governance, the provincial government enacting relevant regulations to standardize the grassroots governance process, and vigorously developing e-government and digital government technologies to enhance the rule of law and standardization in grassroots governance.

Keywords: Path dependence; Mobile governance; Credit-seeking goals; Blame-avoidance goals
Ecol. Civiliz.
2025,
2
(3), 10006; 
Open Access

Article

07 April 2025

Evaluating a Motion-Based Region Proposal Approach with Background Subtraction Methods for Small Drone Detection

The detection of drones in complex and dynamic environments poses significant challenges due to their small size and background clutter. This study aims to address these challenges by developing a motion-based pipeline that integrates background subtraction and deep learning-based classification to detect drones in video sequences. Two background subtraction methods, Mixture of Gaussians 2 (MOG2) and Visual Background Extractor (ViBe), are assessed to isolate potential drone regions in highly complex and dynamic backgrounds. These regions are then classified using the ResNet18 architecture. The Drone-vs-Bird dataset is utilized to test the algorithm, focusing on distinguishing drones from other dynamic objects such as birds, trees, and clouds. By leveraging motion-based information, the method enhances the drone detection process by reducing computational demands. Results show that ViBe achieves a recall of 0.956 and a precision of 0.078, while MOG2 achieves a recall of 0.857 and a precision of 0.034, highlighting the comparative advantages of ViBe in detecting small drones in challenging scenarios. These findings demonstrate the robustness of the proposed pipeline and its potential contribution to enhancing surveillance and security measures.

Keywords: Drone detection; Background subtraction; Small object detection; ResNet18; Motion region proposals
Drones Veh. Auton.
2025,
2
(2), 10007; 
Open Access

Letter

07 April 2025
Open Access

Article

03 April 2025

Design, Building and Performance of a New Photocatalytic Reactor Using TiO2-Coated Rings Synthesized by Plasma Electrolytic Oxidation

An annular UV photocatalytic reactor with recirculation in batch was designed and built. The design considered low construction, simple operation and maintenance costs, availability and durability of the materials used, easy cleaning, and high standards of hygiene and safety. The TiO2 photocatalysts were synthesized by plasma electrolytic oxidation (PEO) on commercial Ti rings were compared with coatings obtained on Ti plates as a reference, and no influence of the substrate geometry on the morphology, crystallinity, or bandgap of the coatings was observed. The efficiency of the photocatalytic reactor using 10 TiO2-coated rings was tested by Cr(VI) transformation in the presence of EDTA. The Cr(VI) transformation after 5 h irradiation attained 95%; a rather high photocatalytic activity (62%) was maintained after the third use of the rings without reactivation of the photocatalyst. These coatings synthesized by PEO have not been applied in modular photocatalytic reactors until now.

Keywords: Annular photoreactor; Titanium dioxide; Plasma electrolytic oxidation; Heterogeneous photocatalysis; Hexavalent chromium; Anodic oxidation; Advanced oxidation processes
Open Access

Editorial

03 April 2025

Sustainable Machining for Difficult-to-Cutting Materials

Intell. Sustain. Manuf.
2025,
2
(1), 10012; 
Open Access

Review

02 April 2025

Wide-Bandgap Semiconductors: A Critical Analysis of GaN, SiC, AlGaN, Diamond, and Ga2O3 Synthesis Methods, Challenges, and Prospective Technological Innovations

The increasing demand for high-performance Wide-Bandgap (WBG) semiconductors, including GaN, SiC, and emerging Ultrawide-Bandgap (UWBG) materials such as Ga2O3 and diamond, has driven significant advancements in epitaxial growth techniques. However, achieving scalability, defect-free growth, and sustainability remains a major challenge. This review systematically evaluates Molecular Beam Epitaxy (MBE), Metal-Organic Chemical Vapor Deposition (MOCVD), Hydride Vapor Phase Epitaxy (HVPE), and other novel growth and hybrid growth techniques, emphasizing energy efficiency, defect control, and environmental impact. Industry 4.0-driven AI-based process optimization and closed-loop recycling have emerged as transformative strategies, reducing waste and improving manufacturing efficiency. Key findings reveal that HVPE enables rapid defect-free GaN fabrication, Hot-Filament CVD enhances SiC growth with superior thermal properties, and Atomic Layer Epitaxy (ALE) achieves sub-nanometer precision crucial for next-generation quantum and RF applications. Despite these advancements, p-type doping in UWBG materials, substrate compatibility, and thermal management remain unresolved challenges. Future research must focus on scalable eco-friendly epitaxy, novel doping mechanisms, and policy-driven sustainability efforts. This review provides a comprehensive roadmap for sustainable WBG semiconductor manufacturing, bridging materials innovation, energy efficiency, and industrial adoption to support the next generation of power electronics and optoelectronics.

Keywords: Wide-bandgap semiconductors; Epitaxial growth; Ultrawide-bandgap semiconductors; Molecular beam epitaxy; Sustainability; Manufacturing
Open Access

Article

02 April 2025

On Hidden Mathematics in the Artwork of the Indigenous People of Brazil

Using examples from indigenous art in Brazil, this paper demonstrates that these works contain “hidden mathematics” (such as symmetry, striped ornaments, rows, etc.), which challenges the traditional notion of “primitive art”.

Keywords: Art; Ethnomathematics; Indigenous art; Geometric patterns; Mathematical aesthetics
Nat. Anthropol.
2025,
3
(2), 10004; 
Open Access

Article

01 April 2025

B, Gd Co-Doped TiO2 Nanotube Arrays for Efficient Degradation of Gaseous Toluene under Visible Light Irradiation

Although photocatalytic degradation of VOCs has attracted widespread attention, the efficient visible-light-driven photocatalytic degradation performance remains a challenge. This work presents the visible-light-driven photocatalytic degradation of gaseous toluene over B, Gd co-doped TiO2 nanotube arrays prepared via a controllable electrochemistry method. It was found that B and Gd co-doping strategy not only enhances the visible light responsiveness of TiO2 nanotube arrays but also introduces moderate oxygen vacancies on the surface of TiO2, which is beneficial to the formation of free hydroxyl radicals and their attack on toluene molecules. The doping order also affects the photocatalytic performance. The optimized sample achieves an enhanced degradation efficiency for toluene under visible light irradiation and exhibits considerable stability. This work may provide an efficient TiO2-based photocatalyst for the removal of volatile organic compounds for air purification and give an understanding of the mechanism of photocatalytic degradation of toluene over co-doping TiO2.

Keywords: TiO2 nanotube array; Photocatalysis; VOCs degradation; Oxygen vacancies; In-suit DRIFTS
Photocatal. Res. Potential
2025,
2
(2), 10010; 
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