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Fulltext Factors associated with knowledge, attitude and practice related to hepatitis B and C among international students of Universiti Putra Malaysia

Ahmad A, Munn Sann L, Abdul Rahman H

BMC Public Health, 2016 07 21;16:611.
PMID: 27443276 DOI: 10.1186/s12889-016-3188-5

BACKGROUND: Knowledge of hepatitis B and C has been reported to be low among respondents in different studies. We conducted a cross-sectional study among international students of Universiti Putra Malaysia (UPM) to ascertain their levels of knowledge, attitude and practices regarding hepatitis B and C and its associated factors.
METHODS: Six hundred and sixty two (662) international students participated in this study. A cluster sampling method was employed and data was generated using self-administered questionnaire, which was validated and its reliability checked.
RESULTS: Normality test was conducted followed by descriptive statistics, spearman's correlation and Chi-square tests to explore associations between variables in the study. The response rate was 71.49 %. Of these, 50.3 % of the respondents had better knowledge of hepatitis B; 52.7 % had better knowledge of hepatitis C; 54.8 % had positive attitude towards hepatitis B and C and 77.6 % had safer practices towards hepatitis B and C. Positive correlations were found between knowledge of hepatitis B and knowledge of hepatitis C; knowledge hepatitis B and attitude; knowledge hepatitis C and attitude; knowledge hepatitis B and practice; knowledge hepatitis C and practice; and attitude and practice regarding hepatitis B and C. Similarly, some socio-demographic variables and history of hepatitis were found to be associated with knowledge, attitude and practice related to hepatitis B and C.
CONCLUSION: The levels of knowledge and attitude towards hepatitis B and C were low among respondents but majority of them exhibited safe practices. The study level, faculty, age, nationality, marital status and gender of the respondents were significantly associated with their levels of knowledge, attitude and practices towards the disease. These findings imply that there is need for hepatitis health promotion among the international students of UPM and possibly other international students across the globe. It will serve to improve their levels of knowledge, attitude and practices in short term and get them protected against the disease in the long run.
Polio and cross-border management

Khan MU, Ahmad A, Balkrishnan R

Lancet Infect Dis, 2017 02;17(2):136.
PMID: 28134106 DOI: 10.1016/S1473-3099(17)30012-9
Frequency-controlled wireless shape memory polymer microactuator for drug delivery application

Zainal MA, Ahmad A, Mohamed Ali MS

Biomed Microdevices, 2017 Mar;19(1):8.
PMID: 28124762 DOI: 10.1007/s10544-017-0148-5

This paper reports the wireless Shape-Memory-Polymer actuator operated by external radio frequency magnetic fields and its application in a drug delivery device. The actuator is driven by a frequency-sensitive wireless resonant heater which is bonded directly to the Shape-Memory-Polymer and is activated only when the field frequency is tuned to the resonant frequency of heater. The heater is fabricated using a double-sided Cu-clad Polyimide with much simpler fabrication steps compared to previously reported methods. The actuation range of 140 μm as the tip opening distance is achieved at device temperature 44 °C in 30 s using 0.05 W RF power. A repeatability test shows that the actuator's average maximum displacement is 110 μm and standard deviation of 12 μm. An experiment is conducted to demonstrate drug release with 5 μL of an acidic solution loaded in the reservoir and the device is immersed in DI water. The actuator is successfully operated in water through wireless activation. The acidic solution is released and diffused in water with an average release rate of 0.172 μL/min.
Fulltext Changes in the morphology of corneal endothelial cells in young myopic adults after 6 months of wearing soft contact lenses: a Malaysian perspective

Ahmad A, Mohd-Ali B, Ishak B

Clin Optom (Auckl), 2018;10:109-113.
PMID: 30319302 DOI: 10.2147/OPTO.S172272

Purpose: Soft contact lens wear is most frequently associated with morphologic changes in corneal endothelial cells, but the data are scarce in Asians. This study aimed to evaluate changes in corneal endothelial cell morphology after 6 months of wearing soft hydrogel contact lenses (SH) in young myopic adults living in Kuala Lumpur.

Patients and methods: Forty-eight subjects were included in the study, 24 were fitted with SH contact lenses (A) and the rest were prescribed with glasses (B). Refraction was conducted subjectively and standard contact lens fitting protocol was followed. Corneal endothelial cell morphology (endothelial cell density, ECD; coefficient of variation, COV; cells' hexagonality, HEX; and central corneal thickness, CCT) was evaluated using specular microscope. Data were collected at baseline and after 6 months of lens wear.

Results: Mean age of all subjects was 21.23±1.30 years. All results are shown at baseline and 6 months, respectively. Mean refraction for A was -2.16±0.97 diopter sphere (DS) and -2.05±1.03 DS (P=0.49); for B was -2.72±1.51 DS and -2.73±1.51 DS (P=0.58). Mean ECD (cell/mm2) for A: 3104.19±237.30 and 3107.23±237.51 (P=0.07); for B: 3011.56±227.95 and 2983.83±244.55 (P=0.33). COV (%) for A: 46.52±8.63 and 48.53±10.65 (P=0.06); for B: 46.93±9.31 and 46.14±10.65 (P=0.88). HEX (%) for A: 46.21±10.12 and 45.15±10.01 (P=0.08); for B: 46.21±10.12 and 45.15±10.01 (P=0.12). CCT (µm) for A: 520.33±0.04 and 525.70±0.05 (P=0.41); for B: 532.00±0.04 µm and 530.00±0.05 µm (P=0.40).

Conclusion: This study found no significant change in corneal endothelial cell morphology after 6 months of wearing SH contact lenses. This is probably due to better oxygen permeability of the contact lens material, good compliance, and short wearing period.
Fulltext Down-regulation of steroidogenesis-related genes and its accompanying fertility decline in streptozotocin-induced diabetic male rats: ameliorative effect of metformin

Nna VU, Bakar ABA, Ahmad A, Mohamed M

Andrology, 2019 01;7(1):110-123.
PMID: 30515996 DOI: 10.1111/andr.12567

BACKGROUND: Metformin has long been used for glycemic control in diabetic state. Recently, other benefits of metformin beyond blood glucose regulation have emerged.
OBJECTIVES: To investigate the effect of metformin on the expression of testicular steroidogenesis-related genes, spermatogenesis, and fertility of male diabetic rats.
MATERIALS AND METHODS: Eighteen adult male Sprague Dawley rats were divided into three groups, namely normal control (NC), diabetic control (DC), and metformin-treated (300 mg/kg body weight/day) diabetic rats (D+Met). Diabetes was induced using a single intraperitoneal injection of streptozotocin (60 mg/kg b.w.), followed by oral treatment with metformin for four weeks.
RESULTS: Diabetes decreased serum and intratesticular testosterone levels and increased serum but not intratesticular levels of luteinizing hormone. Sperm count, motility, viability, and normal morphology were decreased, while sperm nuclear DNA fragmentation was increased in DC group, relative to NC group. Testicular mRNA levels of androgen receptor, luteinizing hormone receptor, cytochrome P450 enzyme (CYP11A1), steroidogenic acute regulatory (StAR) protein, 3β-hydroxysteroid dehydrogenase (HSD), and 17β-HSD, as well as the level of StAR protein and activities of CYP11A1, 3β-HSD, and 17β-HSD, were decreased in DC group. Similarly, decreased activities of epididymal antioxidant enzymes and increased lipid peroxidation were observed in DC group. Consequently, decreased litter size, fetal weight, mating and fertility indices, and increased pre- and post-implantation losses were recorded in DC group. Following intervention with metformin, we observed increases in serum and intratesticular testosterone levels, Leydig cell count, improved sperm parameters, and decreased sperm nuclear DNA fragmentation. Furthermore, mRNA levels and activities of steroidogenesis-related enzymes were increased, with improved fertility outcome.
DISCUSSION AND CONCLUSION: Diabetes mellitus is associated with dysregulation of steroidogenesis, abnormal spermatogenesis, and fertility decline. Controlling hyperglycemia is therefore crucial in preserving male reproductive function. Metformin not only regulates blood glucose level, but also preserves male fertility in diabetic state.
Importance of Stem Cell Migration and Angiogenesis Study for Regenerative Cell-based Therapy: A Review

Aziz NS, Yusop N, Ahmad A

Curr Stem Cell Res Ther, 2020;15(3):284-299.
PMID: 31985383 DOI: 10.2174/1574888X15666200127145923

Stem cells play an essential role in maintaining homeostasis, as well as participating in new tissue regeneration. Over the past 20 years, a great deal of effort has been made to investigate the behaviour of stem cells to enable their potential use in regenerative medicine. However, a variety of biological characteristics are known to exist among the different types of stem cells due to variations in the methodological approach, formulation of cell culture medium, isolation protocol and cellular niches, as well as species variation. In recent years, cell-based therapy has emerged as one of the advanced techniques applied in both medical and clinical settings. Cell therapies aim to treat and repair the injury sites and replace the loss of tissues by stimulating the repair and regeneration process. In order to enable the use of stem cells in regenerative therapies, further characterisation of cell behaviour, in terms of their proliferation and differentiation capacity, mainly during the quiescent and inductive state is regarded as highly necessary. The central focus of regenerative medicine revolves around the use of human cells, including adult stem cells and induced pluripotent stem cells for cell-based therapy. The purpose of this review was to examine the existing body of literature on stem cell research conducted on cellular angiogenesis and migration, to investigate the validity of different strategies and variations of the cell type used. The information gathered within this review may then be shared with fellow researchers to assist in future research work, engaging in stem cell homing for cell-based therapy to enhance wound healing and tissue regeneration process.
In vitro anti-biofilm activity of bacteriocin from a marine Bacillus sp. strain Sh10 against Proteus mirabilis

Shayesteh F, Ahmad A, Usup G

Iran J Microbiol, 2020 Feb;12(1):52-61.
PMID: 32322380

Background and Objectives: Biofilm formed by Proteus mirabilis strains is one of the most important medical problems especially in the case of device-related urinary tract infections. This study was conducted to evaluate the bacteriocin produced by a marine isolate of Bacillus sp. Sh10, for it's in vitro inhibitory activity against pre-formed biofilm and in interference with the biofilm-forming of two biofilm-producing bacteria (P. mirabilis UCa4 and P. mirabilis UCe1).
Materials and Methods: Sensitivity of two biofilm-producing bacteria (P. mirabilis UCa4 and P. mirabilis UCe1) to bacteriocin, was investigated in planktonic and biofilm states by cell viability and crystal violet assay, respectively. Scanning electron microscopy (SEM) was also performed to determine the effect of bacteriocin on the morphology of the cells associated with biofilm.
Results: It was found that bacteriocin possessed bactericidal activity to biofilm-forming isolates in the planktonic state. However, bacteriocin interferes with the formation of biofilms and disrupts established biofilms. Bacteriocin reduced biofilm formation in the isolates of P. mirabilis UCa4 and P. mirabilis UCe1 with SMIC50 of 32 and 128 μg/mL, desirable SMIC50 of bacteriocin for biofilm disruption were 128 and 256 μg/mL, respectively. The SEM results indicated that bacteriocin affected the cell morphology of biofilm-associated cells.
Conclusion: The present findings indicated that bacteriocin from Bacillus sp. Sh10 has bactericidal properties against biofilm-forming isolates of P. mirabilis UCa4 and P. mirabilis UCe1 and has the ability to inhibit the formation of biofilm and disrupt established biofilm.
The effect of educational intervention on enhancing the empathy among nursing students

Ahmad A, Wahab H, Seman N

Enferm Clin, 2020 03;30 Suppl 3:100-103.
PMID: 32331728 DOI: 10.1016/j.enfcli.2019.12.038

With the revision on the concept of empathy, this study attempted to teach empathy to nursing students with the goal of to increase the students' empathy levels.
METHOD: We conducted a quasi-experimental study with a non-equivalent group design and incorporated empathy training, pre- and post-training empathy measurements of participants in a private nursing college (N=64). Empathy scores were measured using the Jefferson Scale of Physician Empathy (2001) and the educational intervention used was Wlodkowski and Ginsberg's Motivational Framework for Culturally Responsive Teaching (1995). Descriptive analysis and paired T-test were used to determine the effect of intervention applied.
RESULTS: The study found increased mean score for both control and experimental group during post-intervention as compared to pre-intervention mean score.
CONCLUSIONS: The result indicates the effectiveness of educational intervention in enhancing empathy among nursing students in the experimental group.
Study site: private nursing college, Malaysia
Fulltext Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity

Yusuf NK, Lajis MA, Ahmad A

Materials (Basel), 2017 Aug 03;10(8).
PMID: 28771207 DOI: 10.3390/ma10080902

Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices.
Fulltext On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process

Ahmad A, Lajis MA, Yusuf NK

Materials (Basel), 2017 Sep 19;10(9).
PMID: 28925963 DOI: 10.3390/ma10091098

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.
Enhanced biosorption of transition metals by living Chlorella vulgaris immobilized in Ca-alginate beads

Ahmad A, Bhat AH, Buang A

Environ Technol, 2019 Jun;40(14):1793-1809.
PMID: 29345546 DOI: 10.1080/09593330.2018.1430171

In this study freely suspended and Ca-alginate immobilized C. vulgaris cells were used for the biosorption of Fe(II), Mn(II), and Zn(II) ions, from the aqueous solution. Experimental data showed that biosorption capacity of algal cells was strongly dependent on the operational condition such as pH, initial metal ions concentration, dosages, contact time and temperature. The maximum biosorption of Fe(II) 43.43, Mn(II) 40.98 and Zn(II) 37.43 mg/g was achieved with Ca-alginate immobilized algal cells at optimum pH of 6.0, algal cells dosage 0.6 g/L, and contact time of 450 min at room temperature. The biosorption efficiency of freely suspended and immobilized C. vulgaris cells for heavy metals removal from the industrial wastewater was validated. Modeling of biosorption kinetics showed good agreements with pseudo-second-order. Langmuir and D-R isotherm models exhibited the best fit of experimental data. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) revealed that the biosorption of considered metal ions was feasible, spontaneous and exothermic at 25-45°C. The SEM showed porous morphology which greatly helps in the biosorption of heavy metals. The Fourier transform infrared spectrophotometer (FTIR) and X-rays Photon Spectroscopy (XPS) data spectra indicated that the functional groups predominately involved in the biosorption were C-N, -OH, COO-, -CH, C=C, C=S and -C-. These results shows that immobilized algal cells in alginate beads could potentially enhance the biosorption of considered metal ions than freely suspended cells. Furthermore, the biosorbent has significantly removed heavy metals from industrial wastewater at the optimized condition.
Fulltext Bibliometric Analysis of Accidental Oil Spills in Ice-Infested Waters

Kabyl A, Yang M, Shah D, Ahmad A

Int J Environ Res Public Health, 2022 Nov 17;19(22).
PMID: 36429909 DOI: 10.3390/ijerph192215190

Oil spills are environmental pollution events that occur due to natural disasters or human activities, resulting in a liquid petroleum hydrocarbon release in the environment, especially into the marine ecosystem. Once oil spills happen, they cause detrimental consequences to the environment, living organisms, and humans. Although there are increasing oil and gas activities in the Arctic region, which is abundant with undiscovered oil and gas resources, the harsh environmental conditions of the region, such as the ice coverage, cold temperatures, long periods of darkness, and its remoteness, pose significant challenges to managing the risk of accidental oil spills in ice-infested waters. In this paper, a bibliometric analysis has been applied to study the global work on oil spill research in ice-infested waters. The paper aims to present an overview of the available oil spill response methods in ice-infested waters, identify the current trends of the research on oil spills in ice-infested waters, and determine the challenges with the future research directions based on the bibliometric analysis. The analysis includes a total number of 77 articles that have been published in this research field which were available in the Scopus database, involving 193 authors from 17 countries dating from 1960 to September 2022. During the bibliometric analysis, the top five most productive authors and countries as well as the most cited publications on oil spills in ice-infested waters have been identified; the authors' cooperation network and the cooperation network between the countries in oil spills research in ice-infested waters have been created; a co-citation analysis and a terms analysis have been performed to identify the popular terms and topics. For future directions, it is recommended for researchers (1) to study real oil spills as much as possible to obtain a good overview through replication under different situations; (2) to develop a new technique for the careful examination and management of the potential risks; (3) to study oil separation from the recovered oil-ice mixture.
Pathogenicity of Aeromonas hydrophila isolated from the Malaysian Sea against coral (Turbinaria sp.) and sea bass (Lates calcarifer)

Hamid R, Ahmad A, Usup G

Environ Sci Pollut Res Int, 2016 Sep;23(17):17269-76.
PMID: 27221587 DOI: 10.1007/s11356-016-6655-8

A study was carried out to determine the pathogenicity (hemolytic activity) on corals (Turbinaria sp.) and sea bass (Lates calcarifer) of Aeromonas hydrophila from water, sediment, and coral. Samples were collected from coastal water and coral reef areas. One hundred and sixty-two isolates were successfully isolated. Out of 162, 95 were from seawater, 49 from sediment, and 18 from coral. Sixteen isolates were picked and identified. Isolates were identified using a conventional biochemical test, the API 20NE kit, and 16S rRNA nucleotide sequences. Hemolytic activity was determined. Out of 16 isolates, 14 isolates were β-hemolytic and two isolates were non-hemolytic. Corals infected with A. hydrophila suffered bleaching. Similar effect was observed for both hemolytic and non-hemolytic isolates. Intramuscular injection of A. hydrophila into sea bass resulted in muscular bleeding and death. Higher infection rates were obtained from hemolytic compared to non-hemolytic strains of A. hydrophila isolates.
Secondary metabolites produced by marine streptomyces as antibiofilm and quorum-sensing inhibitor of uropathogen Proteus mirabilis

Younis KM, Usup G, Ahmad A

Environ Sci Pollut Res Int, 2016 Mar;23(5):4756-67.
PMID: 26538254 DOI: 10.1007/s11356-015-5687-9

Quorum-sensing regulates bacterial biofilm formation and virulence factors, thereby making it an interesting target for attenuating pathogens. In this study, we investigated anti-biofilm and anti-quorum-sensing compounds from secondary metabolites of halophiles marine streptomyces against urinary catheter biofilm forming Proteus mirabilis without effect on growth viability. A total of 40 actinomycetes were isolated from samples collected from different places in Iraq including marine sediments and soil samples. Fifteen isolates identified as streptomyces and their supernatant screened as anti-quorum-sensing by inhibiting quorum-sensing regulated prodigiosin biosynthesis of Serratia marcescens strain Smj-11 as a reporter strain. Isolate Sediment Lake Iraq (sdLi) showed potential anti-quorum-sensing activity. Out of 35 clinical isolates obtained from Urinary catheter used by patient at the Universiti Kebangsaan Malaysia Medical Center, 22 isolates were characterized and identified as Proteus mirabilis. Isolate Urinary Catheter B4 (UCB4) showed the highest biofilm formation with highest resistance to used antibiotic and was chosen for further studies. Ethyl acetate secondary metabolites extract was produced from sdLi isolate. First, we determined the Minimum Inhibitory Concentration (MIC) of sdLi crude extract against UCB4 isolate, and all further experiments used concentrations below the MIC. Tests of subinhibitory concentrations of sdLi crude extract showed good inhibition against UCB4 isolate biofilm formation on urinary catheter and cover glass using Scanning electron microscopy and light microscopy respectively. The influence of sub-MIC of sdLi crude extract was also found to attenuate the quorum sensing (QS)-dependent factors such as hemolysin activity, urease activity, pH value, and motility of UCB4 isolate. Evidence is presented that these nontoxic secondary metabolites may act as antagonists of bacterial quorum sensing by competing with quorum-sensing signals for receptor binding.
The evaluation of water quality and metal concentrations of Titiwangsa Lake, Selangor, Peninsular Malaysia

Said KS, Shuhaimi-Othman M, Ahmad AK

Pak J Biol Sci, 2012 May 15;15(10):459-68.
PMID: 24187900

A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Titiwangsa Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using hydrolab data sonde 4 and surveyor 4 a water quality multi probe (USA). Six metals i.e., cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), perkin elmer elan, model 9000. The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur.
The determination of water quality and metal concentrations of Ampang Hilir Lake, Selangor, Peninsular Malaysia

Said KS, Shuhaimi-Othman M, Ahmad AK

Pak J Biol Sci, 2012 May 01;15(9):437-47.
PMID: 24163953

A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Ampang Hilir Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using Hydrolab Data Sonde 4 and Surveyor 4 a water quality multi probe (USA). Six metals which were cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Perkin Elmer Elan, model 9000.The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur.
The nexus between green intellectual capital, blockchain technology, green manufacturing, and sustainable performance

Umar M, Ahmad A, Sroufe R, Muhammad Z

Environ Sci Pollut Res Int, 2024 Feb;31(10):15026-15038.
PMID: 38285260 DOI: 10.1007/s11356-024-31952-8

Enterprises across the globe are facing increasing pressure to effectively utilize resources and reduce costs through green supply chain practices. Emerging technology, such as blockchain technology which enables green practices, has become a contemporary industrial paradigm. However, enterprises need to build green intellectual capital to implement blockchain technology, which can be key to realizing green supply chain practices. This research examines the impact of green intellectual capital (GIC) on blockchain technology and its role in implementing green manufacturing to achieve sustainability. Partial least squares structural equation modeling was utilized for assessing the proposed hypotheses, and cross-sectional data was accumulated from manufacturing firms. As per the results, GIC, which includes green human capital, green structural capital, and green relational capital has a crucial role in the implementation of blockchain technology. The outcomes also indicated that the adoption of blockchain technology significantly influences green manufacturing. Moreover, green manufacturing (GM) has a substantial role in improving business sustainability. This empirical research provides a deeper understanding of how GIC and blockchain technology contribute to the implementation of GM. This research also provides guidelines that managers, policymakers, and producers can use to facilitate the incorporation of GM practice into business activities.
Fulltext Non-redundant implicational base of formal context with constraints using SAT

Hidayat T, Ahmad A, Ngo HC

PeerJ Comput Sci, 2024;10:e1806.
PMID: 38435549 DOI: 10.7717/peerj-cs.1806

An implicational base is knowledge extracted from a formal context. The implicational base of a formal context consists of attribute implications which are sound, complete, and non-redundant regarding to the formal context. Non-redundant means that each attribute implication in the implication base cannot be inferred from the others. However, sometimes some attribute implications in the implication base can be inferred from the others together with a prior knowledge. Regarding knowledge discovery, such attribute implications should be not considered as new knowledge and ignored from the implicational base. In other words, such attribute implications are redundant based on prior knowledge. One sort of prior knowledge is a set of constraints that restricts some attributes in data. In formal context, constraints restrict some attributes of objects in the formal context. This article proposes a method to generate non-redundant implication base of a formal context with some constraints which restricting the formal context. In this case, non-redundant implicational base means that the implicational base does not contain all attribute implications which can be inferred from the others together with information of the constraints. This article also proposes a formulation to check the redundant attribute implications and encoding the problem into satisfiability (SAT) problem such that the problem can be solved by SAT Solver, a software which can solve a SAT problem. After implementation, an experiment shows that the proposed method is able to check the redundant attribute implication and generates a non-redundant implicational base of formal context with constraints.
Fulltext Gibbons aren't singing in the rain: presence and amount of rainfall influences ape calling behavior in Sabah, Malaysia

Clink DJ, Hamid Ahmad A, Klinck H

Sci Rep, 2020 Jan 28;10(1):1282.
PMID: 31992788 DOI: 10.1038/s41598-020-57976-x

Early morning calling occurs across diverse taxa, which may be related to optimal conditions for sound transmission. There exists substantial inter- and intra-specific variation in calling time which is influenced by intrinsic, social and/or environmental factors. Here, we investigate environmental predictors of calling in gibbons. We hypothesized that male solos- which occur earlier and tend to be longer than duets-would be more influenced by environmental variables, if earlier, longer calling bouts are energetically costly, and therefore limited by overnight energy expenditure. Our top model for male solo events included amount of rain in the previous 24 hours, and explained 30% of the variance, whereas the top model for duet events (which included presence and amount of rainfall) explained only 5% of the variance. Rain the previous night led to a later start time of male solos (~30 minutes), but our top model for duet start time did not include any reliable predictors. Male solo events appear to be more influenced by environmental factors, and duets may be influenced more by social factors. Our results are in line with previous studies that show that changes in overnight conditions -which may alter energy expenditure -can influence early morning calling behavior.
Fulltext Ageing with HIV: health implications and evolving care needs

Ahmad A, Neelamegam M, Rajasuriar R

J Int AIDS Soc, 2020 Sep;23(9):e25621.
PMID: 32996718 DOI: 10.1002/jia2.25621

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