Selective Iron Suppression through Sulfation, Oxidative Calcination, and pH-Controlled Atmospheric Leaching of a Ferruginous Oxidized Copper Ore

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Iron-rich oxidized copper ores are challenging to treat by atmospheric leaching because iron oxides and oxyhydroxides may consume acid and increase impurity loading in the pregnant leach solution. This study evaluated a three-stage route comprising sulfuric-acid sulfation, oxidative calcination, and pH-controlled atmospheric leaching, with the primary objective of minimizing net Fe transfer rather than maximizing Cu extraction. Six distinct operating conditions were investigated using a ferruginous oxidized copper ore from northern Bahia, Brazil, containing 19.6 wt.% Fe, 5.37 wt.% Al, 1.47 wt.% Mg, 0.524 wt.% Mn, and 1.05 wt.% Cu. Commercial sulfuric-acid solution additions during sulfation ranged from 9.75 to 99.69 kg solution/t dry ore. The sulfated products were calcined through staged temperatures from approximately 250 to 700 °C over 6 h and subsequently leached at approximately 90 °C for 180 min, with final solution pH values of 2.33–2.77. Reconciled Fe transfer remained between 0.026% and 0.340%, corresponding to Fe suppression of 99.66–99.97%. By contrast, Mg, Mn, and Al transfers ranged from 6.39% to 29.78%, 38.14% to 59.98%, and 6.95% to 16.28%, respectively, confirming that Fe suppression did not result from a general inhibition of mineral dissolution. The measured Fe transfers corresponded to calculated stoichiometric acid equivalents of only 0.13–1.76 kg H₂SO₄/t ore, compared with an upper-bound requirement of 516.34 kg H₂SO₄/t ore for complete conversion and dissolution of feed Fe as Fe(III) sulfate. The response is consistent with initial formation of ferric sulfate, basic ferric sulfate, or related Fe-bearing sulfate intermediates, followed by thermal destabilization to poorly soluble Fe(III)-oxide-bearing phases and release of sulfur oxides. Released SO₃ may have promoted sulfate redistribution to neighboring reactive metal–oxygen sites, while controlled-pH leaching was consistent with an additional aqueous Fe-rejection barrier through limited Fe-oxide attack and Fe(III) hydrolysis or reprecipitation. Mg behaved as a persistent sulfate sink, Mn showed redox-sensitive transfer, and Al exhibited intermediate behavior. The route therefore selectively decoupled the large Fe inventory from the final aqueous products. Direct-leaching controls and stage-resolved mineralogical, sulfur-speciation, and off-gas analyses are required to quantify actual acid savings and confirm the proposed mechanism.

Stakeholder Salience and Contested Governance in a Sacred Heritage Tourism: Evidence from Sultan Suriansyah Tomb Complex, Indonesia

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The Sultan Suriansyah Tomb Complex is a well-known religious tourist attraction and cultural heritage site in the city of Banjarmasin, rich in the historical significance of the Banjar Sultanate. However, the mausoleum faces a crisis stemming from a conflict over management between the descendants of the sultan and the local community. Therefore, this study aims to analyze stakeholder involvement in its management. This study employs a descriptive qualitative approach, with data collected through observation, literature review, and in-depth interviews with key informants. The data was then analyzed using NVivo 12 for Windows to identify the typology of the stakeholders. The results indicate that the government level falls under the “definitive stakeholder” typology, the descendants’ group and the local community fall under the “dormant stakeholder” typology, and the City’s Cultural Heritage Expert Team (TACB) falls under the “discretionary stakeholder” typology. However, although the government level holds the highest typology, it cannot make final decisions, so management appears to proceed independently without collaboration among actors. In fact, the City Cultural Heritage Expert Team (TACB) is not involved in making final decisions regarding the management of the Sultan Suriansyah Tomb Complex. Thus, management conflicts do not arise from the absence of stakeholders, but rather from an unbalanced distribution of power, legitimacy, and urgency.

Research Skills and Degree Completion Efficiency: A Diagnosis of the Obstacles to Graduation by Thesis

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The expansion in the number of options for obtaining a professional degree at Mexican universities has not translated into an improvement in students’ scientific output. On the contrary, indicators show a gradual decline in the choice of the thesis over standardized examinations, amid an ongoing debate about the usefulness of degree-qualifying projects given the lengthening of graduation times and the delayed entry into the labor market. This article analyzes the socioeconomic, personal, pedagogical, and methodological problems that students of the Bachelor’s program in Communication and Media at the Universidad Autónoma de Nayarit (UAN) face when developing their thesis. Using a quantitative approach and a descriptive cross-sectional design, a questionnaire was administered to a sample of 78 eighth-semester students. The results reveal a contradiction: although the curriculum includes five consecutive research courses, 71.7% of the student body prefers to graduate through the EGEL-CENEVAL examination because they regard it as a faster process. Meanwhile, the 17.8% who consider writing a thesis face long working hours (91%), a lack of accessible advising (73.1%), and a theory-based form of teaching that does not translate into practical scientific-writing skills. It is concluded that the lag stems from factors related to pedagogical and institutional support; therefore, restructuring the research courses into production-workshop formats is proposed.

Effects of Different Levels of DAP on Agronomical Characteristics and Yield of Mung bean

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Phosphorus deficiency is one of the main factors restricting mung bean (Vigna radiata L.) production in many parts of the world, including Afghanistan. Therefore, a field experiment was carried out in the 2025 growing season at the Research Farm of the Faculty of Agriculture, Kabul University, to determine the influence of different diammonium phosphate (DAP) fertilizer levels on mung bean growth and yield. The experiment was arranged in a randomized complete block design (RCBD) with three replications, consisting of four DAP rates: 0, 30, 60, and 90 kg ha⁻¹. The collected growth and yield data were analyzed using analysis of variance (ANOVA), and mean comparisons were performed using the Least Significant Difference (LSD) test at a 5% probability level. The application of DAP fertilizer significantly improved plant height, shoot dry matter, number of branches, pods per plant, pod length, seeds per pod, and 100-seed weight. However, leaf number, grain weight per square meter, seed yield, and harvest index did not show significant differences among fertilizer treatments, although higher values were generally observed compared with the control treatment. The maximum seed yield (870.83 kg ha⁻¹) was obtained from the application of 60 kg DAP ha⁻¹, while the highest performance for most growth and yield-related traits was recorded under 90 kg DAP ha⁻¹. The findings suggest that DAP fertilizer application enhances mung bean growth and yield performance under the environmental conditions of Kabul. Among the tested fertilizer levels, 60 kg DAP ha⁻¹ was found to be the most effective rate for achieving higher grain yield.

Vietnamese Non-English Majors’ Perceptions of the Impact of ChatGPT on Self-Directed Learning: A Study at a Public College

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ChatGPT has attracted considerable interest from educators and researchers in teaching English as a foreign language; however, there is not much empirical evidence about the effects of ChatGPT on EFL learners’ self-directed learning. The current study explores the impact of ChatGPT on self-directed learning among EFL learners in a Vietnamese public college. A mixed-methods research design was used. Both quantitative and qualitative data were collected through a questionnaire and semi-structured interviews through the participation of 144 non-English majors. Data were analyzed quantitatively through descriptive statistics and qualitatively through thematic analysis. Findings revealed that non-English majors mostly used ChatGPT for self-study, language practice, and answer verification. Furthermore, ChatGPT had a moderate positive effect on self-directed learning among participants, especially in terms of personal responsibility and self-regulation. However, ChatGPT’s role in promoting learner autonomy was rather insignificant. The findings imply that ChatGPT may be efficiently integrated into English learning, provided it is done alongside pedagogical guidance and critical assessment of ChatGPT responses by learners.

Poly(3-hydroxybutyrate) Production from Wastewater: Microbial Pathways, Production Strategies, and Sustainability Perspectives

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The increasing accumulation of petroleum-based plastic waste and wastewater has intensified the need for sustainable waste management and biodegradable alternatives. Poly(3-hydroxybutyrate) (P3HB), a microbial biopolymer, has emerged as a promising substitute for conventional plastics. This article reviews the potential of wastewater as a renewable substrate for P3HB production, with emphasis on microbial pathways, production strategies, and sustainability aspects. It discusses different wastewater sources, P3HB-producing microorganisms, metabolic engineering approaches, production processes, and polymer recovery techniques, highlighting the factors that influence productivity and product quality. The integration of P3HB production into biorefinery systems and its contribution to resource recovery, greenhouse gas mitigation, and the circular bioeconomy are also addressed. Overall, wastewater-based P3HB production represents a sustainable and economically attractive approach for biodegradable polymer production, although further technological advances are required to support large-scale industrial implementation.

German Hazardous Substances Law

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German hazardous substances law serves as a national supplement to the requirements of European hazardous substances legislation. Its specific provisions must be taken into account – alongside European rules – when distributing products within the Federal Republic of Germany. Key German regulatory instruments in this field include the German Chemicals Act, the Ordinance on the Prohibition of Chemicals, the Hazardous Substances Ordinance, and the Technical Rules for Hazardous Substances. Their essential contents are presented and discussed. The national legal hierarchy regarding hazardous substances and the enforcement and compliance monitoring carried out by various stakeholders are also addressed.

Differences in Depression, Anxiety, and Stress Scores Across Workload Categories Among Nurses Working at Community Health Centers in Metro City, Lampung Province

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Background: Increasing workloads among nurses working at community health centers, driven by high service demands and limited staffing, may adversely affect mental health, particularly symptoms of depression, anxiety, and stress.

Objective: To examine differences in depression, anxiety, and stress scores across workload categories among nurses working at community health centers administered by the Metro City Health Office.

Methods: This cross-sectional study was conducted from November 2025 to July 2026 at 11 community health centers. A total of 55 nurses were recruited using purposive sampling. Workload was assessed using the National Aeronautics and Space Administration Task Load Index (NASA-TLX), whereas depression, anxiety, and stress were measured using the Depression Anxiety Stress Scale-21 (DASS-21). Data were analyzed using descriptive statistics and the Kruskal-Wallis test, with statistical significance set at p < 0.05.

Results: Most respondents had a high workload (60.0%). The largest proportions of respondents were classified as normal for depression (49.1%), anxiety (54.5%), and stress (83.6%). The Kruskal-Wallis test showed significant differences in depression (p = 0.006), anxiety (p = 0.001), and stress (p = 0.040) scores across workload categories. The high-workload group had the highest mean ranks for depression (33.27), anxiety (34.67), and stress (32.26).

Conclusion: Depression, anxiety, and stress scores differed significantly across workload categories, with the highest mean ranks observed among nurses in the high-workload category. Equitable workload distribution and accessible psychosocial support are needed to protect nurses’ mental health and maintain the quality of healthcare services.

Implementation of YOLOv8n-Based Liveness Detection to Enhance the Security of Facial Attendance Systems Against Real-Time Spoofing Attacks

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This research aims to develop an anti-spoofing security system based on liveness detection to address the vulnerabilities of facial attendance systems against identity manipulation using photos or videos. The methodology employed is quantitative experimental, utilizing the YOLOv8n (You Only Look Once) deep learning architecture. The research stages involved the independent collection of a dataset comprising 8,000 images, categorized into “real” and “fake” face classes. This dataset was processed using a distribution ratio of 70% for training, 20% for validation, and 10% for testing. The model training process was conducted over 50 epochs using the Google Colab platform supported by a Tesla T4 Graphics Processing Unit (GPU). The results indicate that the developed model achieves high performance, with a mean Average Precision (mAP50) of 99.4%, precision of 98.8%, and recall of 99.0%. Real-time testing demonstrated an average inference speed of 20 frames per second (FPS), ensuring system responsiveness in practical applications. Implementation on low-power hardware, specifically the NVIDIA Jetson Nano, confirmed the computational efficiency of the model for edge device deployment. The primary conclusion of this study is that the YOLOv8n-based liveness detection system is highly effective and viable for integration into automated organizational attendance systems due to its high accuracy and efficient power consumption.

Effect of Different Levels of Nitrogen on Growth and Yield of Flax under Kabul Agro-Ecological Conditions

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Flax is among the most significant industrial oilseed crops in the world, as well as in Afghanistan.  It is high in health-promoting fatty acids. However, its yield and quality are low owing to poor nitrogen fertilizer use and lack of improved cultivars in Afghanistan. Hence, a field trial was conducted at the Research Farm of the Agriculture Faculty of Kabul University during the main cropping season of 2025 to evaluate four nitrogen rates (0, 50, 100, and 150 kg/ha). The study was conducted using a randomized complete block design (RCBD) arrangement with four replications. The size of each experimental unit was 2 m × 2 m (4 m2), with six rows. Distances of 30 cm and 40 cm were left between plots and blocks, respectively. The spacing between rows was 30 cm, and the spacing between plants was 15 cm. Significant differences were observed in the different levels of nitrogen on plant height, number of capsules per plant, number of branches per plant, number of seeds per capsule, 1000-seed weight, length of roots, biological yield, grain yield, and straw yield. However, the results showed that the 100 kg N/ha fertilization level significantly outperformed in number of seeds per capsule, number of capsules per plant, 1000-seed weight, and seed yield. Meanwhile, the 150 kg N/ ha fertilization level excelled in plant height and number of branches per plant, biological yield, and straw yield.