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Model of a multiple-line distributed-feedback dye laser

Khan N

Appl Opt, 2004 Jan 20;43(3):678-81.
PMID: 14765930

The theoretical basis for simultaneous oscillation of 2N - 3 laser lines is due to interference of N (for all even N > or = 2) pump beams in a distributed-feedback dye laser is described. Multiple gratings are produced in a dye solution by interference patterns of N/2 pairs of a frequency-doubled Nd:YAG laser. N/2 pairs of mutually time-delayed pulses induce multiple gratings of different periodicities, of which 2N - 3 gratings support oscillation of 2N - 3 lines and the remaining gratings, because of their larger periods, cannot support Bragg scattering. The maximum number of laser lines depends on the mutual delay between adjacent pairs of beams, coherence, states of polarization, pulse lengths, and of course the number of pulses. For three pairs of excitation beams derived from the same source through wave-front or amplitude phase division techniques, the output lasing lines varied from a minimum of three to a maximum of nine. This research was carried out by pumping of a dye solution with two, four, and six pulses, but the principle may be extended to multiple output lines, depending on the number of pump pulses and on the gain of the dye solution.
Nitric oxide accelerates mycorrhizal effects on plant growth and root development of trifoliate orange

Li Tian, Xiao-yun Huang, Qiang-sheng Wu, Nasrullah

Sains Malaysiana, 2017;46:1687-1691.

Arbuscular mycorrhizal fungi (AMF) actively colonize plant roots and thus enhance plant growth through different mechanisms. In the present study, trifoliate orange (Poncirus trifoliata) seedlings inoculated with Diversispora versiformis were subjected to 0 and 0.2 mmol/L sodium nitroprusside (SNP, a nitric oxide donor) treatments. After eight weeks, exogenous SNP considerably increased root mycorrhizal colonization by 25%, showing a positive stimulating effect of NO on mycorrhizal formation. Mycorrhizal inoculation significantly increased plant growth performance (height, stem diameter, leaf number and shoot and root dry weight) and root traits (length, projected area, surface area, volume and number of 2nd and 3rd order lateral roots) than non-mycorrhizal treatment and NO (exogenous SNP treatment) heavily strengthened the mycorrhizal effects. Moreover, NO and mycorrhization induced more fine root (0-0.5 cm) formation. There was an opposite changed trend in root sucrose and leaf and root glucose contents by SNP in AMF versus non-AMF seedlings. All these results implied that NO plays important roles in mycorrhizal formation and development and also accelerates mycorrhizal effects on plant growth and root development of trifoliate orange.
Fulltext Antiplasmodial alkaloids from the bark of Cryptocarya nigra (Lauraceae)

Nasrullah AA, Zahari A, Mohamad J, Awang K

Molecules, 2013 Jul 08;18(7):8009-17.
PMID: 23884132 DOI: 10.3390/molecules18078009

A dichloromethane extract of the stem bark of Cryptocarya nigra showed strong in vitro inhibition of Plasmodium falciparum growth, with an IC50 value of 2.82 μg/mL. The phytochemical study of this extract has led to the isolation and characterization of four known alkaloids: (+)-N-methylisococlaurine (1), atherosperminine (2), 2-hydroxyathersperminine (3), and noratherosperminine (4). Structural elucidation of all alkaloids was accomplished by means of high field 1D- and 2D-NMR, IR, UV and LCMS spectral data. The isolated extract constituents (+)-N-methylisococlaurine (1), atherosperminine (2) and 2-hydroxy-atherosperminine (3) showed strong antiplasmodial activity, with IC50 values of 5.40, 5.80 and 0.75 μM, respectively. In addition, (+)-N-methylisocolaurine (1) and atherosperminine (2) showed high antioxidant activity in a DPPH assay with IC50 values of 29.56 ug/mL and 54.53 ug/mL respectively. Compounds 1 and 2 also both showed high antioxidant activity in the FRAP assay, with percentages of 78.54 and 70.66 respectively and in the metal chelating assay, with IC50 values of 50.08 ug/mL and 42.87 ug/mL, respectively.
The role of iron-based nanoparticles (Fe-NPs) on methanogenesis in anaerobic digestion (AD) performance

Jadhav P, Khalid ZB, Zularisam AW, Krishnan S, Nasrullah M

Environ Res, 2021 Sep 17;204(Pt B):112043.
PMID: 34543635 DOI: 10.1016/j.envres.2021.112043

Several strategies have been proposed to improve the performance of the anaerobic digestion (AD) process. Among them, the use of various nanoparticles (NPs) (e.g. Fe, Ag, Cu, Mn, and metal oxides) is considered one of the most effective approaches to enhance the methanogenesis stage and biogas yield. Iron-based NPs (zero-valent iron with paramagnetic properties (Fe0) and iron oxides with ferromagnetic properties (Fe3O4/Fe2O3) enhance microbial activity and minimise the inhibition effect in methanogenesis. However, comprehensive and up-to-date knowledge on the function and impact of Fe-NPs on methanogens and methanogenesis stages in AD is frequently required. This review focuses on the applicative role of iron-based NPs (Fe-NPs) in the AD methanogenesis step to provide a comprehensive understanding application of Fe-NPs. In addition, insight into the interactions between methanogens and Fe-NPs (e.g. role of methanogens, microbe interaction and gene transfer with Fe-NPs) beneficial for CH4 production rate is provided. Microbial activity, inhibition effects and direct interspecies electron transfer through Fe-NPs have been extensively discussed. Finally, further studies towards detecting effective and optimised NPs based methods in the methanogenesis stage are reported.
High surface area mesoporous activated carbon-alginate beads for efficient removal of methylene blue

Nasrullah A, Bhat AH, Naeem A, Isa MH, Danish M

Int J Biol Macromol, 2018 Feb;107(Pt B):1792-1799.
PMID: 29032214 DOI: 10.1016/j.ijbiomac.2017.10.045

High surface area mesoporous activated carbon-alginate (AC-alginate) beads were successfully synthesized by entrapping activated carbon powder derived from Mangosteen fruit peel into calcium-alginate beads for methylene blue (MB) removal from aqueous solution. The structure and surface characteristics of AC-alginate beads were analyzed using Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and surface area analysis (SBET), while thermal properties were tested using thermogravimetric analysis (TGA). The effect of AC-alginate dose, pH of solution, contact time, initial concentration of MB solution and temperature on MB removal was elucidated. The results showed that the maximum adsorption capacity of 230mg/g was achieved for 100mg/L of MB solution at pH 9.5 and temperature 25°C. Furthermore, the adsorption of MB on AC-alginate beads followed well pseudo-second order equation and equilibrium adsorption data were better fitted by the Freundlich isotherm model. The findings reveal the feasibility of AC-alginate beads composite to be used as a potential and low cost adsorbent for removal of cationic dyes.
Pristine and modified biochar applications as multifunctional component towards sustainable future: Recent advances and new insights

Amalina F, Krishnan S, Zularisam AW, Nasrullah M

Sci Total Environ, 2024 Mar 01;914:169608.
PMID: 38157898 DOI: 10.1016/j.scitotenv.2023.169608

Employing biomass for environmental conservation is regarded as a successful and environmentally friendly technique since they are cost-effective, renewable, and abundant. Biochar (BC), a thermochemically converted biomass, has a considerably lower production cost than the other conventional activated carbons. This material's distinctive properties, including a high carbon content, good electrical conductivity (EC), high stability, and a large surface area, can be utilized in various research fields. BC is feasible as a renewable source for potential applications that may achieve a comprehensive economic niche. Despite being an inexpensive and environmentally sustainable product, research has indicated that pristine BC possesses restricted properties that prevent it from fulfilling the intended remediation objectives. Consequently, modifications must be made to BC to strengthen its physicochemical properties and, thereby, its efficacy in decontaminating the environment. Modified BC, an enhanced iteration of BC, has garnered considerable interest within academia. Many modification techniques have been suggested to augment BC's functionality, including its adsorption and immobilization reliability. Modified BC is overviewed in its production, functionality, applications, and regeneration. This work provides a holistic review of the recent advances in synthesizing modified BC through physical, chemical, or biological methods to achieve enhanced performance in a specific application, which has generated considerable research interest. Surface chemistry modifications require the initiation of surface functional groups, which can be accomplished through various techniques. Therefore, the fundamental objective of these modification techniques is to improve the efficacy of BC contaminant removal, typically through adjustments in its physical or chemical characteristics, including surface area or functionality. In addition, this article summarized and discussed the applications and related mechanisms of modified BC in environmental decontamination, focusing on applying it as an ideal adsorbent, soil amendment, catalyst, electrochemical device, and anaerobic digestion (AD) promoter. Current research trends, future directions, and academic demands were available in this study.
Fulltext Test-Retest Reliability of Level-Specific CE-Chirp Auditory Brainstem Response in Normal-Hearing Adults

Jamal FN, Arafat Dzulkarnain AA, Shahrudin FA, Marzuki MN

J Audiol Otol, 2021 Jan;25(1):14-21.
PMID: 32575950 DOI: 10.7874/jao.2020.00073

BACKGROUND AND OBJECTIVES: There is growing interest in the use of the Level-specific (LS) CE-Chirp® stimulus in auditory brainstem response (ABR) due to its ability to produce prominent ABR waves with robust amplitudes. There are no known studies that investigate the test-retest reliability of the ABR to the LS CE-Chirp® stimulus. The present study aims to investigate the test-retest reliability of the ABR to the LS CE-Chirp® stimulus and compare its reliability with the ABR to standard click stimulus at multiple intensity levels in normal-hearing adults.
SUBJECTS AND METHODS: Eleven normal-hearing adults participated. The ABR test was repeated twice in the same clinical session and conducted again in another session. The ABR was acquired using both the click and LS CE-Chirp® stimuli at 4 presentation levels (80, 60, 40, and 20 dBnHL). Only the right ear was tested using the ipsilateral electrode montage. The reliability of the ABR findings (amplitudes and latencies) to the click and LS CE-Chirp® stimuli within the same clinical session and between the two clinical sessions was calculated using an intra-class correlation coefficient analysis (ICC).
RESULTS: The results showed a significant correlation of the ABR findings (amplitude and latencies) to both stimuli within the same session and between the clinical sessions. The ICC values ranged from moderate to excellent.
CONCLUSIONS: The ABR results from both the LS CE-Chirp® and click stimuli were consistent and reliable over the two clinical sessions suggesting that both stimuli can be used for neurological diagnoses with the same reliability.
How the social media impact women's psychological well-being in the patriarchal structure? The moderating effect of social capital

He L, Firdaus A, Gong J, Dharejo N, Aksar IA

BMC Public Health, 2024 Feb 23;24(1):581.
PMID: 38395820 DOI: 10.1186/s12889-024-18013-y

BACKGROUND: Despite technological, political and economic progress, Pakistan is still a traditionally patriarchal society, and cultural norms curb women's freedom of socialization, which contributes to poor mental health. The digital technology spaces are rampant with male dominance, and offline cultural behaviours are replicated. Therefore, the current research in Pakistan intends to focus solely on women, their social media uses and the consequent impact on their psychological well-being. Furthermore, the mediation role of social capital is explored, which is linked to women's socialization. In virtual communication, women can expand their connection or remain limited to known people.
METHODS: An online survey collected 240 responses from women social media users. The questionnaire was divided into demographics, social media use patterns like access, online time, frequency of use, social media uses, online social capital and psychological well-being. The obtained responses were statistically analyzed using Smart PLS.
RESULTS: Pakistani women use social media extensively; however, their uses are culturally influenced. The women use social media and socialize online but do not openly disclose their personalities and emotions to extend the connection. They seek information only from acquaintances and do not trust newly developed online contacts. Therefore, the mediation role of bonding social capital is significant, referring to the importance of close ties and trust in psychological well-being. Though virtual spaces provide an opportunity for bridging social capital, women use social media for socialization; however, it doesn't contribute to women's psychological well-being.
CONCLUSION: Despite the higher penetration of digital technologies, cultural power still rules in developing countries like Pakistan. Social media uses are gender- and culturally specific, contributing to psychological well-being and developing social capital. The results from Pakistani society recommend ensuring a secure digital experience for women to get maximum benefits from social media and enhance their psychological well-being.
Fulltext Potential biosorbent derived from Calligonum polygonoides for removal of methylene blue dye from aqueous solution

Nasrullah A, Khan H, Khan AS, Man Z, Muhammad N, Khan MI, et al.

ScientificWorldJournal, 2015;2015:562693.
PMID: 25705714 DOI: 10.1155/2015/562693

The ash of C. polygonoides (locally called balanza) was collected from Lakki Marwat, Khyber Pakhtunkhwa, Pakistan, and was utilized as biosorbent for methylene blue (MB) removal from aqueous solution. The ash was used as biosorbent without any physical or chemical treatment. The biosorbent was characterized by using various techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The particle size and surface area were measured using particle size analyzer and Brunauer-Emmett-Teller equation (BET), respectively. The SEM and BET results expressed that the adsorbent has porous nature. Effects of various conditions such as initial concentration of methylene blue (MB), initial pH, contact time, dosage of biosorbent, and stirring rate were also investigated for the adsorption process. The rate of the adsorption of MB on biomass sample was fast, and equilibrium has been achieved within 1 hour. The kinetics of MB adsorption on biosorbent was studied by pseudo-first- and pseudo-second-order kinetic models and the pseudo-second-order has better mathematical fit with correlation coefficient value (R (2)) of 0.999. The study revealed that C. polygonoides ash proved to be an effective, alternative, inexpensive, and environmentally benign biosorbent for MB removal from aqueous solution.
The Effects of Palm Oil on Plasma and Serum Lipid Parameters: A Systematic Review on Animal Intervention Studies

Syarifah-Noratiqah SB, Fairus S, Zulfarina MS, Nasrullah Z, Qodriyah HMS, Naina-Mohamed I

Front Vet Sci, 2020;7:303.
PMID: 32775343 DOI: 10.3389/fvets.2020.00303

Background: Accumulative evidences on the beneficial effects of palm oil are progressively reported; however, there are still several controversies related to their effects on the risks of cardiovascular disease (CVD). This review explores the effects of palm oil and its liquid fraction namely palm olein, which is commonly used as cooking oil on four lipid parameters; total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C), which play an important role as CVD-related biomarkers. A systematic review of the literature was conducted to identify the relevant studies on palm oil and the lipid parameters specifically focusing on the in-vivo animal model. Methods: A comprehensive search was conducted in Medline via EBSCOhost, Medline via OVID and Scopus. Studies were limited to the English language published between the years of 2000 and 2019. The main inclusion criteria were as follows: (1) Study with in-vivo animal experiments [the animal should be limited to mammals] (2) Study should have evaluated the effects of palm oil or palm olein on plasma or serum lipid parameter (3) Study should have used palm oil or palm olein in the form of pure or refined oil (4) The treatment of palm oil or palm olein was assessed using the following outcomes: plasma or serum TC, TG, HDL-C, and LDL-C concentration (5) Study should have control group and (6) studies on specific fatty acid, fraction enriched tocotrienol and tocopherol, crude palm oil, kernel oil, red palm oil, thermally oxidized palm oil, hydrogenated palm oil, and palm oil or palm olein based products namely margarine, palm milk, butter and cream were excluded. The quality and the risk of bias on the selected studies were assessed using the ARRIVE Guideline and SYRCLE's Risk of Bias tools, respectively. Results: The literature search successfully identified 17 potentially relevant articles, whereby nine of them met the inclusion criteria. All research articles included in this review were in vivo studies comprising seven rats, one hamster and one mice model. Conclusion: Significant positive outcomes were observed in several lipid parameters such as TC and LDL-C. The evidence from this review supported that palm oil and palm olein possess high potential as lipid-lowering agents.
The role of conductive nanoparticles in anaerobic digestion: Mechanism, current status and future perspectives

Kumar SS, Ghosh P, Kataria N, Kumar D, Thakur S, Pathania D, et al.

Chemosphere, 2021 Oct;280:130601.
PMID: 33945900 DOI: 10.1016/j.chemosphere.2021.130601

In the current scenario, alternative energy sources are the need of the hour. Organic wastes having a larger fraction of biodegradable constituents present a sustainable bioenergy source. It has been reported that the calorific value of biogas generated by anaerobic digestion (AD) is 21-25 MJ/m3 with the treatment which makes it an excellent replacement of natural gas and fossil fuels and can reduce more than 80% greenhouse gas emission to the surroundings. However, there are some limitations associated with the AD process for instance ammonia build-up at the first stage reduces the rate of hydrolysis of biomass, whereas, in the last stage it interferes with methane formation. Owing to special physicochemical properties such as high activity, high reactive surface area, and high specificity, tailor-made conductive nanoparticles can improve the performance of the AD process. In the AD process, H2 is used as an electron carrier, referred as mediated interspecies electron transfer (MIET). Due to the diffusion limitation of these electron carriers, the MIET efficiency is relatively low that limits the methanogenesis. Direct interspecies electron transfer (DIET), which enables direct cell-to-cell electron transport between bacteria and methanogen, has been considered an alternative efficient approach to MIET that creates metabolically favorable conditions and results in faster conversion of organic acids and alcohols into methane. This paper discusses in detail the application of conductive nanoparticles to enhance the AD process efficiency. Interaction between microbes in anaerobic conditions for electron transfer with the help of CNPs is discussed. Application of a variety of conductive nanomaterials as an additive is discussed with their potential biogas production and treatment enhancement in the anaerobic digestion process.
Co-digestion of palm oil mill effluent for enhanced biogas production in a solar assisted bioreactor: Supplementation with ammonium bicarbonate

Zaied BK, Nasrullah M, Siddique MNI, Zularisam AW, Singh L, Krishnan S

Sci Total Environ, 2020 Mar 01;706:136095.
PMID: 31862587 DOI: 10.1016/j.scitotenv.2019.136095

Lack of sufficient nitrogenous substrate and buffering potential have been acknowledged as impediments to the treatment of palm oil mill effluent through co-digestion processes. In this study, ammonium bicarbonate was used to provide the nitrogenous substrate and buffering potential. To regulate the impact of ammonium bicarbonate toxicity on the anaerobic co-digestion system, dosages from 0 to 40 mg/L were supplemented. The biogas yield was used to indicate the effects of NH4+ toxicity. In a solar-assisted bioreactor, solar radiation was first collected by a solar panel and converted into electricity, which was then used to heat a mixture of palm oil mill effluent and cattle manure to maintain the reactor in the mesophilic temperature range. This co-digestion operation was performed semi-continuously and was analyzed at a 50:50 mixing ratio of palm oil mill effluent and cattle manure. The results indicate that the additional dosing of ammonium bicarbonate can significantly enhance biogas production. Maximum cumulative biogas and methane productions of 2034.00 mL and 1430.51 mL, respectively, were obtained with the optimum addition of 10 mg/L ammonium bicarbonate; these values are 29.80% and 42.30% higher, respectively, than that obtained in the control co-digestion operation without addition of ammonium bicarbonate. Utilization of a mathematical equation (G = Gmk/t) to describe a kinetic analysis of the biogas yield also indicated that the optimum ammonium bicarbonate dose was 10 mg/L. The results of this study suggest that supplementation with ammonium bicarbonate doses of up to 40 mg/L can be used to provide nitrogenous substrates and buffering potential in anaerobic co-digestion processes. The determination of the optimal dose provides an alternative and efficient option for enhanced biogas production, which will have obvious economic advantages for feasible industrial applications.
A comprehensive review on contaminants removal from pharmaceutical wastewater by electrocoagulation process

Zaied BK, Rashid M, Nasrullah M, Zularisam AW, Pant D, Singh L

Sci Total Environ, 2020 Jul 15;726:138095.
PMID: 32481207 DOI: 10.1016/j.scitotenv.2020.138095

The pharmaceuticals are emergent contaminants, which can create potential threats for human health and the environment. All the pharmaceutical contaminants are becoming enormous in the environment as conventional wastewater treatment cannot be effectively implemented due to toxic and intractable action of pharmaceuticals. For this reason, the existence of pharmaceutical contaminants has brought great awareness, causing significant concern on their transformation, occurrence, risk, and fate in the environments. Electrocoagulation (EC) treatment process is effectively applied for the removal of contaminants, radionuclides, pesticides, and also harmful microorganisms. During the EC process, an electric current is employed directly, and both electrodes are dissoluted partially in the reactor under the special conditions. This electrode dissolution produces the increased concentration of cation, which is finally precipitated as hydroxides and oxides. Different anode materials usage like aluminum, stainless steel, iron, etc. are found more effective in EC operation for efficient removal of pharmaceutical contaminants. Due to the simple procedure and less costly material, EC method is extensively recognized for pharmaceutical wastewater treatment over further conventional treatment methods. The EC process has more usefulness to destabilize the pharmaceutical contaminants with the neutralization of charge and after that coagulating those contaminants to produce flocs. Thus, the review places particular emphasis on the application of EC process to remove pharmaceutical contaminants. First, the operational parameters influencing EC efficiency with the electroanalysis techniques are described. Second, in this review emerging challenges, current developments and techno-economic concerns of EC are highlighted. Finally, future recommendations and prospective on EC are envisioned.
Efficient conversion of lignocellulosic biomass to levulinic acid using acidic ionic liquids

Khan AS, Man Z, Bustam MA, Nasrullah A, Ullah Z, Sarwono A, et al.

Carbohydr Polym, 2018 Feb 01;181:208-214.
PMID: 29253965 DOI: 10.1016/j.carbpol.2017.10.064

In the present research work, dicationic ionic liquids, containing 1,4-bis(3-methylimidazolium-1-yl) butane ([C4(Mim)2]) cation with counter anions [(2HSO4)(H2SO4)0], [(2HSO4)(H2SO4)2] and [(2HSO4)(H2SO4)4] were synthesised. ILs structures were confirmed using 1H NMR spectroscopy. Thermal stability, Hammett acidity, density and viscosity of ILs were determined. Various types of lignocellulosic biomass such as rubber wood, palm oil frond, bamboo and rice husk were converted into levulinic acid (LA). Among the synthesized ionic liquids, [C4(Mim)2][(2HSO4)(H2SO4)4] showed higher % yield of LA up to 47.52 from bamboo biomass at 110°C for 60min, which is the better yield at low temperature and short time compared to previous reports. Surface morphology, surface functional groups and thermal stability of bamboo before and after conversion into LA were studied using SEM, FTIR and TGA analysis, respectively. This one-pot production of LA from agro-waste will open new opportunity for the conversion of sustainable biomass resources into valuable chemicals.
Characterisation of synthesised trimetallic nanoparticles and its influence on anaerobic digestion of palm oil mill effluent

Jadhav P, Krishnan S, Kamyab H, Khalid ZB, Bhuyar P, Zularism AW, et al.

Chemosphere, 2024 Jan;346:140512.
PMID: 37879373 DOI: 10.1016/j.chemosphere.2023.140512

The augmentation of biogas production can be achieved by incorporating metallic nanoparticles as additives within anaerobic digestion. The objective of this current study is to examine the synthesis of Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles using the co-precipitation technique and assess its impact on anaerobic digestion using palm oil mill effluent (POME) as carbon source. The structural morphology and size of the synthesised trimetallic nanoparticles were analysed using a range of characterization techniques, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) . The average size of Fe-Ni-Zn and Fe-Co-Zn were 19-25.5 nm and 19.1-30.5 nm respectively. Further, investigation focused on examining the diverse concentrations of trimetallic nanoparticles, ranging from 0 to 50 mgL-1. The biogas production increased by 55.55% and 60.11% with Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles at 40 mgL-1 and 20 mgL-1, respectively. Moreover, the lowest biogas of 11.11% and 38.11% were found with 10 mgL-1 of Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles. The findings of this study indicated that the trimetallic nanoparticles exhibited interactions with anaerobes, thereby enhancing the degradation process of palm oil mill effluent (POME) and biogas production. The study underscores the potential efficacy of trimetallic nanoparticles as a viable supplement for the promotion of sustainable biogas generation.
Statistical optimization of titanium recovery from drinking water treatment residue using response surface methodology

Krishnan S, Zulkapli NS, Din MFM, Majid ZA, Honda M, Ichikawa Y, et al.

J Environ Manage, 2020 Feb 01;255:109890.
PMID: 31790869 DOI: 10.1016/j.jenvman.2019.109890

Water treatment plants generate vast amounts of sludge and its disposal is one of the most expensive and environmentally problematic challenges worldwide. As sludge from water treatment plants contains a considerable amount of titanium, both can create serious environmental concerns. In this study, the potential to recover titanium from drinking water treatment residue was explored through acid leaching technique. Statistical design for the optimization of titanium recovery was proposed using response surface methodology (RSM) based on a five-level central composite design (CCD). Three independent variables were investigated, namely the acid concentration (3 M-7 M), temperature (40 °C - 80 °C) and solid/liquid ratio (0.005-0.02 g/mL). According to the analysis of variance (ANOVA), the p-value (<0.0001) indicated the designed model was highly significant. Optimization using RSM gave the best fit between validated and predicted data as elucidated by the coefficient of determination with R2 values of 0.9965. However, acid concentration and solid/liquid ratio showed an initial increase in titanium recovery followed by recovery reduction with increasing concentration and ratio. Quadratic RSM predicted the maximum recovery of titanium to be 67.73% at optimal conditions of 5.5 M acid concentration, at a temperature of 62 °C with a solid/liquid ratio of 0.01 g/mL. The verification experiments gave an average of 66.23% recovery of titanium, thus indicating that the successfully developed model to predict the response. This process development has significant importance to reduce the cost of waste disposal, environmental protection, and recovery of economically valuable products.
Performance evaluation and energy potential analysis of anaerobic membrane bioreactor (AnMBR) in the treatment of simulated milk wastewater

Moideen SNF, Krishnan S, Li YY, Hassim MH, Kamyab H, Nasrullah M, et al.

Chemosphere, 2023 Mar;317:137923.
PMID: 36682635 DOI: 10.1016/j.chemosphere.2023.137923

An anaerobic membrane bioreactor (AnMBR) was employed as primary treatment unit for anaerobic treatment of simulated wastewater to produce high effluent quality. A lab scale hollow fiber membrane was used to scrutinize the performance of AnMBR as a potential treatment system for simulated milk wastewater and analyze its energy recovery potential. The 15 L bioreactor was operated continuously at mesophilic conditions (35 °C) with a pH constant of 7.0. The membrane flux was in the range of 9.6-12.6 L/m2. h. The different organic loading rates (OLRs) of 1.61, 3.28, 5.01, and 8.38 g-COD/L/d, of simulated milk wastewater, were fed to the reactor and the biogas production rate was analyzed, respectively. The results revealed that the COD removal efficiencies of 99.54 ± 0.001% were achieved at the OLR of 5.01 gCOD/L/d. The highest methane yield was found to be at OLR of 1.61 gCOD/L/d at HRT of 30 d with the value of 0.33 ± 0.01 L-CH4/gCOD. Moreover, based on the analysis of energy balance in the AnMBR system, it was found that energy is positive at all the given HRTs. The net energy production (NEP) ranged from 2.594 to 3.268 kJ/gCOD, with a maximum NEP value of 3.268 kJ/gCOD at HRT 10 d HRT. Bioenergy recovery with the maximum energy ratio, of 4.237, was achieved with an HRT of 5 d. The study suggests a sizable energy saving with the anaerobic membrane process.
Fulltext Optimization of operating parameters for xylose reductase separation through ultrafiltration membrane using response surface methodology

Krishnan S, Suzana BN, Wahid ZA, Nasrullah M, Abdul Munaim MS, Din MFBM, et al.

Biotechnol Rep (Amst), 2020 Sep;27:e00498.
PMID: 32670809 DOI: 10.1016/j.btre.2020.e00498

The application of the xylose reductase (XR) enzyme in the development of biotechnology demands an efficient and large scale enzyme separation technique. The aim of this present work was to optimize xylose reductase (XR) purification process through ultrafiltration membrane (UF) technology using Central composite design (CCD) of response surface methods (RSM). The three effective parameters analyzed were filtration time (0-100), transmembrane pressure (TMP) (1-1.6 bar), cross flow velocity (CFV) (0.52-1.2 cm/s-1) and its combined effect to obtain high flux with less possibility of membrane fouling. Experimental studies revealed that the best range for optimization process for filtration time, operational transmembrane pressure and cross flow velocity was 30 min, 1.4 bars and 1.06 cm/s, respectively as these conditions yielded the highest membrane permeability (56.03 Lm-2h-1 bar-1) and xylitol content (15.49 g/l). According to the analysis of variance (ANOVA), the p-value (<0.0001) indicated the designed model was highly significant. The error percentage between the actual and predicted value for membrane permeability and xylitol amount (2.21 % and 4.85 % respectively), which both were found to be close to the predicted values. The verification experiments gave membrane actual permeability of 57.3 Lm-2h-1 bar-1 and 16.29 g/l of xylitol production, thus indicating that the successfully developed model to predict the response.
Fulltext Survival and Characteristics of Bladder Cancer: Analysis of the Malaysian National Cancer Registry

Nik Ab Kadir MN, Mohd Hairon S, Yaacob NM, Ab Manan A, Ali N

Int J Environ Res Public Health, 2021 05 14;18(10).
PMID: 34069096 DOI: 10.3390/ijerph18105237

BACKGROUND: Bladder cancer ranked ninth of principal male cancer in Malaysia. This study aimed to evaluate the clinical characteristics and survival of bladder cancer patients in Malaysia.
METHODS: A retrospective cohort study was conducted by obtaining records in the Malaysian National Cancer Registry. Patients aged 15 years old and above with diagnosis date between 2007 and 2011 were included. Death was updated until 31 December 2016. Five-year observed survival and median survival time were determined by the life table method and Kaplan-Meier estimate method.
RESULTS: Among 1828 cases, the mean (SD) age of diagnosis was 64.9 (12.5) years. The patients were predominantly men (78.7%), Malay ethnicity (49.4%) and transitional cell carcinoma (78.2%). Only 14.8% of patients were at stage I. The overall five-year observed survival and median survival time was 36.9% (95% CI: 34.6, 39.1) and 27.3 months (95% CI: 23.6, 31.0). The highest five-year observed survival recorded at stage I (67.6%, 95% CI: 62.0, 73.3) and markedly worsen at stage II (34.3%, 95% CI: 27.9, 40.8), III (25.7%, 95% CI: 18.7, 32.6) and IV (12.2%, 95% CI: 8.1, 16.3).
CONCLUSIONS: Survival of bladder cancer patients in Malaysia was lower with advancing stage. The cancer control programme should be enhanced to improve survival.
Effects of Stimulus Repetition Rates on the Auditory Brainstem Response to Level-Specific CE-Chirp in Normal-Hearing Adults

Dzulkarnain AAA, Shahrudin FA, Jamal FN, Marzuki MN, Mazlan MNS

Am J Audiol, 2020 Dec 09;29(4):838-850.
PMID: 32966099 DOI: 10.1044/2020_AJA-20-00049

Purpose The purpose of this study is to investigate the influence of stimulus repetition rates on the auditory brainstem response (ABR) to Level-Specific (LS) CE-Chirp and click stimuli at multiple intensity levels in normal-hearing adults. Method A repeated-measure study design was used on 13 normal-hearing adults. ABRs were acquired from the study participants using LS CE-Chirp and click stimuli at four stimulus repetition rates (19.1, 33.3, 61.1, and 81.1 Hz) and four intensity levels (80, 60, 40, and 20 dB nHL). The ABR test was stopped at 40-nV residual noise level. Results High-stimulus repetition rates caused the ABR latencies to be longer and have reduced amplitudes in both ABR to LS CE-Chirp and click stimuli. The ABR to LS CE-Chirp Wave I, III, and V amplitudes were larger than ABR to click in almost all the stimulus repetition rates. However, there were no differences in the number of averages required to reach the stopping criterion between ABR to LS CE-Chirp and click stimulus, and between high-stimulus repetition rates and low-stimulus repetition rates. Conclusion The LS CE-Chirp at standard low-stimulus repetition rates can be used to elicit ABR for both neurodiagnostic and threshold seeking procedure.

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