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Purpose – The research was carried out in order to study the composition of minerals, content of total-K, total-Ca, total-Mg, and exchangeable of K, Ca, Mg in volcanish ash from Sinabung volcano eruption.

Design/Methodology/Approach – The volcanic ash material in amount of 5 kg was collected from the depth of 0–20 cm and 21–41 cm. Mineral composition was determined by using line counting method; total contents of K, Ca, and Mg were measured by HCl 1N extraction, and exchangeable of K, Ca, and Mg was measured by NH₄OAc 1N pH 7.0 extraction.

Purpose – The results depicted in volcanic ash layer at the depth of 0–20 cm found some minerals such as plagioclase (34%), hypersthene (9%), augite (3%), hornblende/amphibole (5%), and volcanic glass (1%). These minerals were also found in different amounts at a depth of 21–41 cm. Hypersthene and amphibole were higher and augite was lower at a depth of 0–20 cm than 21–41 cm. The total content of K, Ca, and Mg was found to be 2.27%, 8.12%, and 2.28%, respectively, at a depth of 0–20 cm. The exchangeable of K, Ca, and Mg was found in an amount of 1.89 me/100 g, 20.71 me/100 g, and 1.62 me/100 g, respectively. The total content of K, Ca, and Mg was not available to plants but could potentially be as a source of plant nutrient after weathering while exchangeable form can be uptaken by plant directly.

Research Limitations/Implications – Based on the composition of the minerals, total, and exchangeable of K, Ca, and Mg that the material of volcanic ash, it could potentially be used as source of fertilizers.

Originality/Value – The composition of primary minerals contained in volcanic ash and to know the amount of elements K, Ca, and Mg-associated minerals either in total or exchange.

This study aims to investigate the effects of mineral rents, conflict and population growth on countries' growth, with a specific interest in 13 selected economies in Sub-Saharan Africa.

This paper uses a combination of research methods: the pooled ordinary least squares (OLS), the fixed effect and the system generalized method of moment (GMM). The consistent estimator (system GMM), which provides the paper's empirical findings, remedies the inherent endogeneity bias in the model formulation. The utilized panel dataset for the study spans from 1980 to 2022.

The study suggests that mineral rents positively affect countries' growth by about 0.407 percentage points in the short run. The study further demonstrates the long-run negative impacts of population growth rates and prevalence of civil war on economic growth. The empirical work of the study reveals that an increase in the number of international borders within the group promotes mineral conflicts, which impedes economic growth. Evidence from the specification tests performed in the study confirmed the validity of the empirical results.

Mineral rents, if well managed and conditioned on good institutions, are a blessing to an economy, contrary to the assumptions that mineral resources are a curse. The utilization of mineral rents in Sub-Saharan Africa for economic growth depends on several factors, notably the level of mineral conflicts, population growth rates, institutional factors and the ability to contain civil war, among others.

This study is the first attempt in the post-coronavirus disease 2019 (COVID-19) era to revisit the investigation of the impacts of mineral rents, conflict and population growth rates on the countries' growth while controlling for the potential implications of the qualities of institutions. One of the significant contributions of the study is the identification of high population growth rates as one of the primary drivers of mineral conflicts that impede economic growth in the states with enormous mineral deposits in Sub-Saharan Africa. The crucial inference drawn from the study is that mineral rents positively impact countries' growth, even with inherent institutional challenges, although the results could be better with good institutions.

The purpose of this paper is to deliberate on the establishment of zakat (Islamic alms) on oil and gas in Malaysia. Being one of the five Islamic pillars, zakat contributes significantly to the country’s socio-economic development and prosperity. However, in Malaysia and other Islamic countries, there is not yet a proper mechanism for calculating zakat on extracted minerals. Similar to gold and silver, oil and gas are valuable minerals, which, upon extraction, are subject to zakat payment. In Malaysia, however, this is not the case.

This study uses a qualitative method. It presents a thorough review on the stipulation for paying zakat on minerals, specifically oil and gas. The deliberation is based on secondary data entailing a comprehensive content analysis of prominent books on the subject, current zakat rulings and legal acts on oil and gas.

Oil and gas are subject to zakat payment, as indicated in several Qurʾānic verses and based on the academic reasoning of Muslim scholars. The zakat calculation for oil and gas entails the nisāb (minimum threshold value of the assets) but not the ḥawl (the requirement for one full Islamic year of ownership for the assets), by analogy with zakat on agricultural produce. Despite the obligation to pay zakat on minerals under the zakāt al-māl (alms due on wealth) category, oil and gas is yet to be fully subject to this practice in Malaysia, although the country is known as an oil-producing Muslim country. Several legislative acts covering the managerial and business side of oil and gas operations have long been established, but the provision on zakat remains unclear. Hence, comprehensive legislation is needed to fine-tune the Malaysian oil and gas system, particularly with regard to zakat.

This study relies mainly on secondary data and literature without performing any empirical investigations.

In terms of academic implication, this study enriches the existing body of knowledge on zakat. Practical implications would include enhanced decision-making concerning zakat on oil and gas on the part of zakat institutions, policymakers and the government of Malaysia.

This study provides practical and academic contributions to the deep understanding of zakat on oil and gas, which has received very little attention in the existing body of literature. Despite being limited in literature, this is a breakthrough study that sheds light on zakat on oil and gas.

This study aims to evaluate the caffeinated drinks, levels of vitamin D and calcium in the blood, and their relationship to bone mineral density (BMD) in osteoporotic women in Al-Ahsa Saudi Arabia.

This study included 85 women over approximately 18 months with ages ranging from 40 to 70 years who were evaluated in the laboratory via blood analysis. Moreover, sociodemographic data and information on health and nutritional awareness were collected via a questionnaire. The BMD was measured by dual-energy X-ray absorptiometry (DXA) and considered osteopenia when the T value total of the lumbar spine or hip was between −1 and −2.5 and osteoporosis < −2.5. Blood levels of vitamin D and calcium were measured via blood analysis.

There were 54.1% and 45.9% of women who suffered from osteoporosis and low BMD, respectively. There was a significant difference in the number of osteoporotic, and low bone mineral mass groups in marital status (p = 0.04), but no difference was found in age and educational level. A significant difference (p = 0.01) between low bone mass and osteoporosis groups in heights. BMD was significantly and negatively correlated with vitamin D in the blood in individuals with osteoporosis (r = −0.358, P = 0.014). In addition, there was a significant negative correlation between calcium in the blood and total samples (r = −0.355, P = 0.0578). There was a negative significant relationship between calcium supplements and BMD in individuals with low BMD (rt = −0.279, P = 0.041). There was a significant association between cola intake with the occurrence of low BMD (p = 0.027), whereas tea drinking was not associated with risk in both groups.

The study indicated that there is a direct relationship between osteoporosis and low bone mass with different variables. This study was conducted to address the lack of research related to the levels of vitamin D and calcium in the blood and their relationship with BMD in women with low BMD and osteoporosis in Al-Ahsa province-KSA.

The purpose of this study is to develop a novel general mathematical model to find the optimal product mix of commercial graphite products, which has a complex production process with alternative sub-processes in the graphite mining production process.

The network optimization was adopted to model the complex graphite mining production process through the optimal allocation of raw graphite, byproducts, and saleable products with comparable sub-processes, which has different processing capacities and costs. The model was tested on a selected graphite manufacturing company, and the optimal graphite product mix was determined through the selection of the optimal production process. In addition, sensitivity and scenario analyses were carried out to accommodate uncertainties and to facilitate further managerial decisions.

The selected graphite mining company mines approximately 400 metric tons of raw graphite per month to produce ten types of graphite products. According to the optimum solution obtained, the company should produce only six graphite products to maximize its total profit. In addition, the study demonstrated how to reveal optimum managerial decisions based on optimum solutions.

This study has made a significant contribution to the graphite manufacturing industry by modeling the complex graphite mining production process with a network optimization technique that has yet to be addressed at this level of detail. The sensitivity and scenario analyses support for further managerial decisions.

This paper investigates the dynamic patterns of Vietnam’s comparative advantage in the context of ASEAN. Using the Galtonian regression method and the Markov transition probability matrices for data from 1997 to 2008, we find the following: Firstly, commodity groups with a weak comparative advantage improved their competitiveness, whereas those groups with a strong comparative advantage saw it decline, indicating a convergence of their comparative advantages. Secondly, in terms of intra-distribution dynamics, industries with no initial comparative advantage (Class a) and those with a strong initial comparative advantage (Class d) showed a high degree of persistence, suggesting a low degree of mobility in the trade patterns for Classes a and d. Thirdly, mineral resource-intensive products showed a high degree of export specialization, whereas other product categories showed a high degree of export diversification. Fourthly, all commodity groups showed a downward trend in the degree of specialization. Finally, Vietnam’s exports were dominated by unskilled labor-intensive products and agricultural resource-intensive products, reflecting the validity of Heckscher-Ohlin model. As a result of the country’s trade liberalization, the patterns of Vietnam’s comparative advantage have come to reflect its factor endowment. These results suggest that Vietnam could better diversify its export structures and shift to exports based on human capital and technology by further liberalizing its trade policies, fostering human capital formation, and facilitating the transfer of technology.

Apart from the basic material properties of liquid lubricants, such as, e.g., the viscosity and density of the hydraulic fluid, it is also important to have information regarding the electrical properties of the fluid used. The latter is closely related to the purpose, type, structure, and conditions of use of a hydraulic system, especially the powertrain design and fluid condition monitoring. The insulating capacity of the hydraulic fluid is important in cases where the electric motor of the pump is immersed in the fluid. In other cases, on the basis of changing the electrical conductive properties of the hydraulic fluid, we can refer its condition, and, on this basis, the degree of degradation.

The paper first highlights the importance of knowing the electrical properties of hydraulic fluids and then aims to compare these properties, such as the breakdown voltage of commonly used hydraulic mineral oils and newer ionic fluids suitable for use as hydraulic fluids.

Knowledge of this property is crucial for the design approach of modern hydraulic compact power packs. In the following, the emphasis is on the more advanced use of known electrical quantities, such as electrical conductivity and the dielectric constant of a liquid.

Based on the changes in these quantities, we have the possibility of real-time monitoring the hydraulic fluid condition, on the basis of which we judge the degree of fluid degradation and its suitability for further use.