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Fulltext Investigation of struvite crystals formed in palm oil mill effluent anaerobic digester

Ngatiman M, Jami MS, Abu Bakar MR, Subramaniam V, Loh SK

Heliyon, 2021 Jan;7(1):e05931.
PMID: 33490684 DOI: 10.1016/j.heliyon.2021.e05931

The formation of struvite crystals or magnesium ammonium phosphate (MgNH4PO4) in palm oil mill effluent (POME) occurs as early as in the secondary stage of POME treatment system. Its growth continues in the subsequent tertiary treatment which reduces piping diameter, thus affecting POME treatment efficiency. Hypothesis. The beneficial use of the crystal is the motivation. This occurrence is rarely reported in scientific articles despite being a common problem faced by palm oil millers. The aim of this study is to characterize struvite crystals found in an anaerobic digester of a POME treatment facility in terms of their physical and chemical aspects. The compositions, morphology and properties of these crystals were determined via energy dispersive spectroscopy (EDS), elemental analysis, scanning electron microscopy (SEM) and x-ray diffraction (XRD). Solubility tests were carried out to establish solubility curve for struvite from POME. Finally, crystal growth experiment was done applying reaction crystallization method to demonstrate struvite precipitation from POME. Results showed that high phosphorous (P) (24.85 wt%) and magnesium (Mg) (21.33 wt%) content was found in the struvite sample. Elemental analysis detected carbon (C), hydrogen (H), nitrogen (N) and sulfur (S) below 4 wt%. The crystals analysed by XRD in this study were confirmed as struvite with 94.8% struvite mineral detected from its total volume. Having an orthorhombic crystal system, struvite crystals from POME recorded an average density of 1.701 g cm-3. Solubility curve of struvite from POME was established with maximum solubility of 275.6 mg L-1 at pH 3 and temperature 40 °C. Minimum solubility of 123.6 mg L-1 was recorded at pH 7 and temperature 25 °C. Crystal growth experiment utilizing POME as the source medium managed to achieve 67% reduction in phosphorous content. This study concluded that there is a potential of harnessing valuable nutrients from POME in the form of struvite. Struvite precipitation technology can be adapted in the management of POME in order to achieve maximum utilization of the nutrients that are still abundant in POME. At the same time maximization of nutrient extractions from POME will also reduce pollutants loading in the final discharge.
Fulltext Field demonstration of irradiated sodium alginate as tea production booster

Hossain MA, Islam JMM, Hoque MM, Nahar S, Khan MA

Heliyon, 2021 Jan;7(1):e05881.
PMID: 33458447 DOI: 10.1016/j.heliyon.2020.e05881

Sodium alginate oligomers were tested for tea plant growth promoter and anti-fungal agent in this experiment. Sodium alginate solutions were irradiated by Co-60 gamma radiation with different radiation doses to produce the oligomers. Irradiated solutions were then diluted into 150, 300 and 500 ppm prior to foliar application. Solutions were applied through foliar spraying at 7 days interval and the best response of tea plants in terms of various attributes were recorded. Tea buds were collected in 10 days of interval and the growth attributes like- total number of buds, fresh weight of buds, average leaf area and weight per bud, weight of made tea etc. were calculated. The experiment was continued up to 12 weeks and the attributes were averaged to get results per plucking. 12 kGy radiation doses along with 300ppm solution showed the best results and about 36% increase in productivity was found based on the fresh weight of buds. Total fungal count in tea leaves was also found to be reduced greatly. Based on the present study, irradiated sodium alginate could be used as safe and environmentally friendly agent to increase tea production.
Fulltext Metabolome analysis and chemical profiling of Indonesian royal jellies as the raw material for cosmetic and bio-supplement products

Sari E, Mahira KF, Patel DN, Chua LS, Pratami DK, Sahlan M

Heliyon, 2021 May;7(5):e06912.
PMID: 34013079 DOI: 10.1016/j.heliyon.2021.e06912

Royal jellies (RJs) possess moisturizing, emulsifying, and stabilizing properties, and several pharmacological activities have also been found to be present, which make them an ideal component for cosmetic and skin care products. However, despite the abundant efficacies, there is a lack of studies that explore the chemical composition of RJ using metabolome analysis. Furthermore, an evaluation of the chemical composition of Indonesian RJs collected from different regions has yet to be carried out. Therefore, the main objective of this study was to identify any differences in the chemical composition of such RJs. Chemical profiling was also carried out to enable more targeted utilization based on the actual compositions. Chemical profiling is also important given the rich Indonesian biodiversity and the high dependence of the RJ compositions on the botanical source. In this research, ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used as part of an untargeted metabolomics approach. From the chemical profiling, >30 compounds were identified across four RJ samples. The major constituents of the samples were found to be oligosaccharides, fatty acids, and adenosine monophosphate derivatives. Meanwhile, sucrose and planteose were found to be highest in the samples from Banjarnegara and Kediri, whereas dimethyloctanoic acid was found to be unique to the sample from Banjarnegara. It was also discovered that the RJs from Demak and Tuban contained more organic fatty acids and oligosaccharides than the other samples. Although the sample from Demak demonstrated good potential for use in the cosmetic, skin care, and bio-supplement industries, the higher abundance of fatty acids and oligosaccharides in the sample from Tuban indicated that it is perhaps the most suitable RJ for use in this field.
Fulltext In-service training and teaching resource proficiency amongst Chemistry teachers: the mediating role of teacher collaboration

Copriady J, Zulnaidi H, Alimin M, Albeta SW

Heliyon, 2021 May;7(5):e06995.
PMID: 34027189 DOI: 10.1016/j.heliyon.2021.e06995

This study aims to determine the level of collaboration, in-service training and teaching resource proficiency amongst Chemistry teachers by investigating the intermediary role of collaboration for training and teaching resources competency. A total of 184 Chemistry teachers in Riau, Indonesia, have participated in the survey. Using AMOS and SPSS 25.0 software to analyse the research data, we find a high level of collaboration, training and teaching resource proficiency amongst Chemistry teachers. Male teachers have higher proficiency level on all aspects than female teachers. The MANOVA test results show a significant difference in teacher resource competency based on gender. Male teachers are significantly more proficient than their female counterparts. However, they do not significantly differ in terms of collaboration and in-service training. The structural equation modelling test results show that collaboration has a significant role in Chemistry teachers' involvement in training and teaching resources. These research findings encourage relevant parties to design effective collaborations amongst Chemistry teachers. They also offer new insights for Chemistry teachers to keep on mastering teaching resources nationally and internationally.
Fulltext Potential anti-Acanthamoeba and anti-adhesion activities of Annona muricata and Combretum trifoliatum extracts and their synergistic effects in combination with chlorhexidine against Acanthamoeba triangularis trophozoites and cysts

Mitsuwan W, Sin C, Keo S, Sangkanu S, de Lourdes Pereira M, Jimoh TO, et al.

Heliyon, 2021 May;7(5):e06976.
PMID: 34027178 DOI: 10.1016/j.heliyon.2021.e06976

Plants with medicinal properties have been used in the treatment of several infectious diseases, including Acanthamoeba infections. The medicinal properties of Cambodian plant extracts; Annona muricata and Combretum trifoliatum were investigated against Acanthamoeba triangularis. A total of 39 plant extracts were evaluated and, as a result, 22 extracts showed positive anti-Acanthamoeba activity. Of the 22 extracts, 9 and 4 extracts showed anti-Acanthamoeba activity against trophozoites and cysts of A. triangularis, respectively. The minimum inhibitory concentration of A. muricata and C. trifoliatum extracts against trophozoites and cysts was 500 and 1,000 μg/mL, respectively. The combination of A. muricata at 1/4×MIC with chlorhexidine at 1/8×MIC demonstrated a synergistic effect against trophozoites, but partial synergy against cysts. A 40% reduction in trophozoites and 60% of cysts adhered to the plastic surface treated with both extracts at 1/2×MIC were noted comparing to the control (P < 0.05). Furthermore, a reduction of 80% and 90% of trophozoites adhered to the surface was observed after pre-treatment with A. muricata and C. trifoliatum extracts, respectively. A 90% of cysts adhered to the surface was decreased with pre-treatment of A. muricata at 1/2×MIC (P < 0.05). A 75% of trophozoites and cysts from Acanthamoeba adhered to the surface were removed after treatment with both extracts at 4×MIC (P < 0.05). In the model of contact lens, 1 log cells/mL of trophozoites and cysts was significantly decreased post-treatment with both extracts compared to the control. Trophozoites showed strong loss of acanthopodia and thorn-like projection pseudopodia, while cysts demonstrated retraction and folded appearance treated with both extracts when observed by SEM, which suggests the potential benefits of the medicinal plants A. muricata and C. trifoliatum as an option treatment against Acanthamoeba infections.
Fulltext Environmental and socioeconomic impacts of pipeline transport interdiction in Niger Delta, Nigeria

Umar HA, Abdul Khanan MF, Ogbonnaya C, Shiru MS, Ahmad A, Baba AI

Heliyon, 2021 May;7(5):e06999.
PMID: 34027190 DOI: 10.1016/j.heliyon.2021.e06999

Over the years, pipelines have been the most economic medium for transporting crude oil to production and distribution facilities in the Niger Delta area of Nigeria. However, damages to the pipelines in this area by interdiction have hampered the continuous flow of crude oil to the facilities. Consequently, the revenue of the government dwindles, and the environment is severely degraded. This study assesses the economic and environmental impacts of pipeline interdiction in the Niger Delta region. Data from National oil spills detection and response agency, Nigeria is used to map spatial distribution of oil spills using Kernel Density Estimation with Geographic Information System. Literature was assessed to synthesize the historical, socioeconomic, and environmental impacts of oil spills and pipeline interdiction. Soil samples were collected from study area to determine the types of hydrocarbon pollutants and their concentrations in comparison with uncontaminated sites in the area. Results show that the range of concentrations of total petroleum hydrocarbon (TPH) for the impacted soil (IMP) was 17.27-58.36 mg/kg; remediated soil (RS) was 11.73-50.78 mg/kg which were higher than the concentrations of 0.68 mg/kg in the control samples (CS). Polycyclic aromatic hydrocarbons (PAH) concentrations were in the range of 0.43-77.54 mg/kg for IMP, 0.42-10.65 mg/kg for RS, against CS value of 0.49 mg/kg while BTEX ranged between 0.02 - 0.38 mg/kg for IMP, 0.01-2.7 for RS against CS value of 0.01. The values of the PAH were higher than the limits of the Department of Petroleum Resources, Nigeria. This study also revealed that pipeline interdiction has affected the livelihood of the inhabitants of the study area and the revenue of the Nigerian government. The major hotspots for oil spills in the Niger Delta region are Bayelsa, Rivers and Delta states.
Fulltext Destination image's mediating role between perceived risks, perceived constraints, and behavioral intention

Nazir MU, Yasin I, Tat HH

Heliyon, 2021 Jul;7(7):e07613.
PMID: 34368481 DOI: 10.1016/j.heliyon.2021.e07613

This study aims to examine the effect of destination image, perceived risk, and perceived constraints on the behavioral intention of international tourists to revisit Pakistan. The study also seeks to assess the destination image's mediating role in the relationship between perceived risks, perceived constraints, and behavioral intention. A quantitative study with Partial least square structural equation modeling was used to investigate the research Hypothesis. The data was collected from international tourists who were in Pakistan or who had visited Pakistan. The findings revealed that perceived risks and perceived constraints negatively impact destination image and behavioral intention. On the other hand, destination image has a positive impact on behavior. Moreover, the study also proved the mediating effect of destination image among the relations of perceived risks, perceived constraints, and behavioral intention. These findings indicate that sometimes it is difficult for destinations to overcome constraints, so destination managers should provide value-added services for substitutes. A positive destination image can overcome risks and constraints, so destination managers should also promote destinations besides mitigating risks. Literature has discussed the mediating effect of destination image in different contexts. However, studies are scarce investigating destination image's effect in alleviating perceived constraints and perceived risks through negotiation mechanisms.
Fulltext Bracing NK cell based therapy to relegate pulmonary inflammation in COVID-19

Jeyaraman M, Muthu S, Bapat A, Jain R, Sushmitha ES, Gulati A, et al.

Heliyon, 2021 Jul;7(7):e07635.
PMID: 34312598 DOI: 10.1016/j.heliyon.2021.e07635

The contagiosity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has startled mankind and has brought our lives to a standstill. The treatment focused mainly on repurposed immunomodulatory and antiviral agents along with the availability of a few vaccines for prophylaxis to vanquish COVID-19. This seemingly mandates a deeper understanding of the disease pathogenesis. This necessitates a plausible extrapolation of cell-based therapy to COVID-19 and is regarded equivalently significant. Recently, correlative pieces of clinical evidence reported a robust decline in lymphocyte count in severe COVID-19 patients that suggest dysregulated immune responses as a key element contributing to the pathophysiological alterations. The large granular lymphocytes also known as natural killer (NK) cells play a heterogeneous role in biological functioning wherein their frontline action defends the body against a wide array of infections and tumors. They prominently play a critical role in viral clearance and executing immuno-modulatory activities. Accumulated clinical evidence demonstrate a decrease in the number of NK cells in circulation with or without phenotypical exhaustion. These plausibly contribute to the progression of pulmonary inflammation in COVID-19 pneumonia and result in acute lung injury. In this review, we have outlined the present understanding of the immunological response of NK cells in COVID-19 infection. We have also discussed the possible use of these powerful biological cells as a therapeutic agent in view of preventing immunological harms of SARS-CoV-2 and the current challenges in advocating NK cell therapy for the same.
Fulltext How does organizational leadership contribute to the firm performance through social responsibility strategies?

Saeidi P, Robles LAA, Saeidi SP, Zamora MIV

Heliyon, 2021 Jul;7(7):e07672.
PMID: 34401561 DOI: 10.1016/j.heliyon.2021.e07672

Despite the wide-ranging studies on Corporate Social Responsibility (CSR), firm performance, and Organizational Leadership (OL), there have been only a few studies examining the inter-relationship between them. Accordingly, this investigation has tried to investigate how OL contributes to the firm's performance through the CSR strategies. It has an internal orientation to CSR motivations compared to the existing studies that mostly considered the external factors in implementing of CSR in firms; also, it has a comprehensive view toward the firm's performance by considering both financial and non-financial aspects of performance. It could be said that this study has tried to answer the question of whether or not CSR can be as a mediator between the OL and firm performance. Data collection was performed from 285 manufacturing and consumer products firms located in Malaysia during the four-month period of June-September of 2020. AMOS Structural Equation Modeling (AMOS-SEM) method was applied to analyze the model. Following the Baron and Kenny approach in testing the hypotheses, it was found that the relationships of OL and financial performance, as well as OL and non-financial performance were partially mediated by CSR. In addition, the non-financial performance was found as a full mediator between the OL and financial performance. Further, the results revealed two full mediated relationships in this way that non-financial performance was a full mediator variable between CSR and financial performance, as well as CSR and non-financial performance which were found as two multiple full mediators between OL and financial performance. The results help Malaysian managers to understand their current status, capabilities, strong points and weaknesses in leadership regarding to CSR. Moreover, due to the positive effects of CSR on both firm's financial and non-financial performance, CSR is recommended to be integrated in leadership style and the organizational strategies in order to having better performance.
Fulltext Compatibility of household appliances with DC microgrid for PV systems

Sabry AH, Shallal AH, Hameed HS, Ker PJ

Heliyon, 2020 Dec;6(12):e05699.
PMID: 33364486 DOI: 10.1016/j.heliyon.2020.e05699

DC distribution of PV systems has spread back especially in the residential sector as a variety of electronic appliances became locally available in the market. The compatibility of household appliances with the best voltage-level in a DC environment is the field that still in the research phase and has not yet made a practically extensive appearance. This paper mainly discusses this issue by providing a review of the concerning research efforts, identifying the gaps in the existing knowledge. The work explains the electrical diagrams of the recently produced appliances, classifying them to get an understanding of how each one consumes energy. It includes exploiting the recent dependence of the commercial appliances on power electronics to improve the efficiency of the existing DC distribution systems by extrapolating new architectures. The proposed topology has a DC distribution environment with two levels of voltage for all appliances. Appliances performances have been evaluated by calculating the energy transfer efficiency. The outcomes of this work can help in designing more efficient DC power distribution networks with minimal energy converters and establishing standardizations for DC microgrids.
Fulltext Industry 4.0 implementation and Triple Bottom Line sustainability: An empirical study on small and medium manufacturing firms

Jayashree S, Reza MNH, Malarvizhi CAN, Mohiuddin M

Heliyon, 2021 Aug;7(8):e07753.
PMID: 34430741 DOI: 10.1016/j.heliyon.2021.e07753

Background: The current level of industrialization has generated many challenges worldwide, including ecological hazards, climate change, and the overuse of non-renewable natural resources, thereby creating an increasing demand for achieving the goal of the Triple Bottom Line (TBL). In this regard, Industry 4.0 can be used as a crunch point to contribute to the production process that can help achieve sustainable development.
Purpose: While the Malaysian government proposed the "Industry4ward" approach to enhance technological adoption, there is scarce empirical evidence in the literature that validates SMEs for Industry 4.0. Using Dynamic Capability View (DCV), this study proposes a framework that includes core determinants like top management commitment, supply chain integration, and IT infrastructure, that can significantly influence Industry 4.0 implementation toward achieving TBL sustainability.
Design/methodology/approach: Employing simple random sampling, the study adopted a quantitative approach based on 199 useable respondent's feedback collected through a survey questionnaire of 900 employees from Malaysian SMEs. The statistical analysis was performed using Structural Equation Modeling (Partial Least Square, SmartPLS 3.3.2).
Findings: The results show that top management and IT infrastructure significantly impact Industry 4.0 implementation and sustainability. In contrast, the analysis also demonstrates that supply chain integration is insignificant to Industry 4.0 implementation in SMEs. The findings also indicate that the relationship between the determinants of Industry 4.0 and TBL sustainability can be mediated by the "effective implementation" of Industry 4.0.
Recommendations: The study highlights the practical consequences of the role and use of the determinants in Industry 4.0 implementation. Its findings help managers and policy-makers to optimize value creation to achieve sustainable development goals.
Limitations and future research: Focusing only on Malaysian manufacturing SMEs may restrict the generalization of the study; thus, a benchmarking analysis from other industrial settings is encouraged. The questionnaire-based survey is a further limitation of the study.
Fulltext Corrigendum to "Compatibility of household appliances with DC microgrid for PV systems" [Heliyon 6 (12), (December 2020) Article e05699]

Sabry AH, Shallal AH, Hameed HS, Ker PJ

Heliyon, 2021 Aug;7(8):e07744.
PMID: 34430735 DOI: 10.1016/j.heliyon.2021.e07744

[This corrects the article DOI: 10.1016/j.heliyon.2020.e05699.].
Fulltext An optimisation study of a solar tower receiver: the influence of geometry and material, heat flux, and heat transfer fluid on thermal and mechanical performance

Shatnawi H, Lim CW, Ismail FB, Aldossary A

Heliyon, 2021 Jul;7(7):e07489.
PMID: 34307940 DOI: 10.1016/j.heliyon.2021.e07489

The solar receiver is considered the cornerstone of the solar tower power system. In particular, it receives high-temperature heat flux rays, and extracts the maximum heat energy to be transferred to the heat transfer fluid, while minimising any thermal and mechanical stresses. Reducing the solar receiver size helps to reduce the loss of spillage; consequently, the thermal stress increases. Using a solar receiver with inserted triangular longitudinal fins enhances the heat transfer as well as strengthens the receiver tube. This study aims to optimise the number of fins, heat flux aiming point, heat transfer fluid, nanoparticle effect with molten salt as the base fluid, and type of receiver material. Non-uniform heat flux with the cosine and Gaussian effects have been considered. When the number of fins (N) increases, the maximum temperature (Tmax) decreases and the heat transfer is enhanced. When N = 20, Tmax = 656.4 K and when N = 1, Tmax = 683.55, while the efficiency for N = 1 is greater by 3% compared to when N = 20. The cosine distribution of heat flux has a higher maximum temperature than the Gaussian distribution by 29% and is 102% higher in receiver efficiency. The thermal efficiency when the heat flux is aimed at the middle point of the receiver is higher by 10% compared with a lower or upper aiming point. Using Al2O3 nanoparticles with a concentration of 0.5 wt.% increases the thermal efficiency by 14% more than when using pure molten salt when Re = 38000. Using liquid sodium is not required to monitor the peak heat flux, and by adding triangular fins the displacement and thermal stress are 6.5 % lower compared to a smooth receiver.
Fulltext The mediating effect of interpersonal distrust on the relationship between perceived organizational politics and workplace ostracism in higher education institutions

Karim DN, Abdul Majid AH, Omar K, Aburumman OJ

Heliyon, 2021 Jun;7(6):e07280.
PMID: 34258449 DOI: 10.1016/j.heliyon.2021.e07280

Despite a widespread consensus towards the implications of workplace ostracism to employees, little research attention has been paid to exploring its determinants, especially in the educational sector. In the context of higher education institutions, workplace ostracism can lead to a number of undesired outcomes, such as deviant workplace behavior, turnover, and decreased job performance. Thus, this study aims to explore the role of perceived organizational politics in promoting workplace ostracism. Drawing on the social exchange theory, the study also attempts to identify the mediating role of interpersonal distrust in the relationship between perceived organizational politics and workplace ostracism in higher education institutions. Data were conveniently collected from 154 full-time faculty members serving in five public universities in Bangladesh. To test the research hypotheses, the study employed partial least squares path modeling. The findings revealed that there is a significant positive association between perceived organizational politics and workplace ostracism and that interpersonal distrust plays an intervening role in the relationship. These results highlight the role of perceived organizational politics and interpersonal distrust in shaping academics' workplace ostracism. Based on the findings, the study suggests both practical and theoretical implications with directions for future research.
Fulltext Clinical and genetic profile in index patients with spinocerebellar ataxia type 3 in Indonesia: case report

Aminah S, Huda F, Gamayani U, Pusparini I, Mochyadin MFA, Sribudiani Y, et al.

Heliyon, 2021 Jul;7(7):e07519.
PMID: 34345727 DOI: 10.1016/j.heliyon.2021.e07519

Spinocerebellar ataxia (SCA) is an autosomal dominant hereditary disease with progressive course, and no causal therapy. Diagnostics are still challenging, due to facility and protocols, and so as in Indonesia. As a national referral center, Dr. Hasan Sadikin Central General Hospital has received a lot of patients from all over Indonesia, particularly from Western Java. Study related to SCA (including clinical and genetic profile) is still limited in Indonesia. We identified index patients from three families with ataxia, hence intend to determine their clinical and genetic pattern. The hereditary pattern is autosomal dominant. Scale for the assessment and rating of ataxia (SARA) shows mild and moderate ataxia. Inventory of non-ataxia signs (INAS) scores of the patients were 3, 5 and 6. Montreal cognitive assessment-Indonesian version (MOCA-INA) shows only one patient has mild cognitive impairment, despite young age. Barthel index shows 1 subject has moderate dependency. Mutation in Ataxin3 polyQ repeats shows pathologically long CAG repeats, 72,10; 72,10; and 72,23 respectively in mutant and wild type allele. We diagnosed the index patients with spinocerebellar ataxia type 3. This study is the first case series study in Indonesia. The hereditary pattern is clearly shown as an autosomal dominant ataxia. The clinical and genetic profile was varied, and the symptom is progressive and deteriorates overtime, including wide based gait, speech problem, motor and sensor complaint, and cognitive decline complaint. Despite the same polyQ stretch length, the onset and clinical characteristics of patients are diverse.
Microwave-assisted catalysis of water-glycerol solutions for hydrogen production over NiO/zeolite catalyst

Husin H, Mahidin M, Pontas K, Ahmadi A, Ridho M, Erdiwansyah E, et al.

Heliyon, 2021 Jul;7(7):e07557.
PMID: 34355081 DOI: 10.1016/j.heliyon.2021.e07557

In this study, glycerol as an abundant green feedstock was used as a hydrogen source to investigate the reaction of water-glycerol solution decomposition by microwave-assisted catalytic to produce hydrogen over NiO/zeolite catalyst. The catalyst was prepared by inception wetness and then characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy diffraction X-ray (EDX), and transmission electron microscope (TEM) measurements. The conversion process of glycerol into hydrogen was performed in a fixed-bed microwave-assisted reactor. Effect of microwave power, NiO content, and feed flow rate (FFR) on glycerol conversion and hydrogen selectivity were studied. The results of XRD and EDX measurement showed that NiO crystalline exists on the catalyst sample. The particle size of NiO/zeolite was determined in the range of 30-300 nm, and the particle was found well dispersed on the zeolite surface as confirmed by TEM. Furthermore, the maximum conversion rate can achieve about 96.67 %, while the highest hydrogen production was found up to 73.5 % with the condition of 20% of NiO as an active site on natural zeolite. It was found that the NiO content of 20% gave the best glycerol conversion at the microwave power of 600 W and FFR 0.5 ml/min. Microwave-assisted catalytic irradiation of glycerol appears to be a promising candidate for the production of H2 from an aqueous glycerol solution.
Fulltext The roles of machine learning methods in limiting the spread of deadly diseases: A systematic review

Alfred R, Obit JH

Heliyon, 2021 Jun;7(6):e07371.
PMID: 34179541 DOI: 10.1016/j.heliyon.2021.e07371

Machine learning (ML) methods can be leveraged to prevent the spread of deadly infectious disease outbreak (e.g., COVID-19). This can be done by applying machine learning methods in predicting and detecting the deadly infectious disease. Most reviews did not discuss about the machine learning algorithms, datasets and performance measurements used for various applications in predicting and detecting the deadly infectious disease. In contrast, this paper outlines the literature review based on two major ways (e.g., prediction, detection) to limit the spread of deadly disease outbreaks. Hence, this study aims to investigate the state of the art, challenges and future works of leveraging ML methods to detect and predict deadly disease outbreaks according to two categories mentioned earlier. Specifically, this study provides a review on various approaches (e.g., individual and ensemble models), types of datasets, parameters or variables and performance measures used in the previous works. The literature review included all articles from journals and conference proceedings published from 2010 through 2020 in Scopus indexed databases using the search terms Predicting Disease Outbreaks and/or Detecting Disease using Machine Learning. The findings from this review focus on commonly used machine learning approaches, challenges and future works to limit the spread of deadly disease outbreaks through preventions and detections.
Fulltext Meso-microporous activated carbon derived from Raffia palm shells: optimization of synthesis conditions using response surface methodology

Iwar RT, Ogedengbe K, Katibi KK, Oshido LE

Heliyon, 2021 Jun;7(6):e07301.
PMID: 34189325 DOI: 10.1016/j.heliyon.2021.e07301

This study investigated the optimal synthesis conditions for the production of Raffia Palm Shell Activated Carbon (RPSAC) using phosphoric acid as activation agent. The optimization of the synthesis conditions was achieved using the Central Composite Design (CDD) in Response Surface Methodology (RSM). The influences of impregnation ratio, temperature, time and concentration on the specific surface area and yield of RPSAC were evaluated. Based on the CDD, 2FI and quadratic models were developed for the two responses. Analysis of Variance (ANOVA) was utilized to determine the significant factors and factor interactions for each response. All process variables except impregnation ratio were observed to significantly influence the quality of RPSAC. The optimal synthesis conditions for RPSAC were; 523.68 °C, 76.91%, and 103.83 min for temperature, concentration, and time respectively which provided a specific surface area and yield of 1762.92 m2/g and 77.98 % respectively. The Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analyses proved that RPSAC had a meso-micro-porous morphology with high carbon and oxygen contents. Fourier-transform infrared spectroscopy (FTIR) revealed the abundance of hydroxyl, carbonyl and carboxylic groups on RPSAC. X-ray Powder Diffraction (XRD) analysis showed that RPSAC composed mainly of amorphous and disordered microcrystalline phases ascribed to the high quartz content of the precursor. The Brunauer-Emmett-Teller (BET) surface area, average pore diameter, total pore volume, and pHpzc of RPSAC were obtained as 456.10 m2/g, 0.25 cm3/g, 2.13 nm and 2.10 correspondingly. Thus, RSM was found to be an excellent and desirable tool for optimal synthesis of RPSAC that possess high surface area and porosity suitable for application in the adsorption of both large and small molecular sized pollutants such as dyes and fluoride in real and aqueous solution.
Fulltext Ultra low-pressure filtration system for energy efficient microalgae filtration

Wan Osman WNA, Mat Nawi NI, Samsuri S, Bilad MR, Khan AL, Hunaepi H, et al.

Heliyon, 2021 Jun;7(6):e07367.
PMID: 34222699 DOI: 10.1016/j.heliyon.2021.e07367

Microalgae-based products have gained growing interest leading to an increase in large-scale cultivation. However, the high energy associated with microalgae harvesting becomes one of the bottlenecks. This study evaluated an energy-efficient microalga harvesting via ultra-low-pressure membrane (ULPM) filtration (<20 kPa) in combination with aeration. ULPM offered various benefits especially in terms of reducing the energy consumption due to it operated under low transmembrane pressure (TMP). High TMP often associated with high pumping energy hence would increase the amount of energy consumed. In addition, membrane with high TMP would severely affect by membrane compaction. Results showed that membrane compaction leads to up to 66 % clean water permeability loss when increasing the TMP from 2.5 to 19 kPa. The Chlorella vulgaris broth permeabilities decreased from 1660 and 1250 to 296 and 251 L/m2hrbar for corresponding TMPs for system with and without aeration, respectively. However, it was found that membrane fouling was more vulnerable at low TMP due to poor foulant scouring from a low crossflow velocity in which up to 56 % of permeability losses were observed. Membrane fouling is the biggest drawback of membrane system as it would reduce the membrane performance. In this study, aeration was introduced as membrane fouling control to scour-off the foulant from membrane surface and pores. In terms of energy consumption, it was observed that the specific energy consumption for the ULPM were very low of up to 4.4 × 10-3 kWh/m3. Overall, combination of low TMP with aeration offers lowest energy input.
Fulltext Physico-chemical characteristics of nanocellulose at the variation of catalytic hydrolysis process

Rashid ESA, Gul A, Yehya WAH, Julkapli NM

Heliyon, 2021 Jun;7(6):e07267.
PMID: 34195407 DOI: 10.1016/j.heliyon.2021.e07267

In this work, the influence of various sulfuric acid (H2SO4) concentration is studied towards the crystallinity, particle size distribution, thermal stability, and morphology of the synthesized nanocellulose (NCC) during the esterification process. Different concentrations of H2SO4 (40%, 58%, 64% and 78%) was utilized to achieve the optimal properties of NCC. The as-produced NCC was characterized by Fourier Transmission Infra-Red (FTIR) analysis that confirmed the attachment of sulphate ions ( SO 4 - 3 ) to C-6 of the glucose ring. Moreover, the hydrogen ions (H+) weakened the C-6 of cellulose chains by attacking the glycosidic linkages resulting in the formation of NCC. The X-Ray Diffraction (XRD) analysis revealed an increase in the crystallinity index with increasing H2SO4 concentration till 78%. NCC represented a needle shaped like structure having a particle size of 10-18 nm in diameter as observed under Atomic Force Microscopy (AFM) and Fourier Emission Scanning Electron Microscopy (FESEM). Furthermore, Dynamic Light Scattering (DSL) analysis recorded the particle size of the NCC as less than 20 nm in diameter. Thus, owing to various H2SO4 concentration the particle size, crystallinity, and features of NCC are substantially affected.

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