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Fulltext Enhancing employment outcome among stable psychiatric patients: lesson learnt on innovative model of work inclusion

Khalid K, Jamaluddin R, Ismail MS

BMJ Open Qual, 2023 Jun;12(2).
PMID: 37277216 DOI: 10.1136/bmjoq-2022-002139

BACKGROUND: Poor employment rate among psychiatric patients is poorly discussed.
PURPOSE: To share our strategies in boosting employment rate among stable psychiatric patients and discuss the lessons learnt.
PARTICULAR FOCUS: Multifaceted strategies were remodelled to ensure a three-dimensional optimisation: (1) strengthening clinical service to ensure stable disease and appropriate patient selection through battery of assessments, (2) provision of psychosocial support to boost self-esteem and foster discipline among patients through encouragement, guidance and regular monitoring by the multidisciplinary community mental health team and (3) encourage willingness and confidence among stakeholders and local market to host job opportunities to stable mental health patients.
OVERVIEW: The yearly employment rate among our stable psychiatric patients under supported employment programme from 2020 to 2021 was 28.6% (2/7) and 30.0% (3/10), respectively. A qualitative survey found the main hindrance to recruitment were employers' scepticism on work performance, while poor work retention was due to patients' lack of specific skill set and discipline to adhere to routine. We restructured our supported employment programme by adding the role of community mental health facility to foster discipline and routine for 6 months prior to referral to a job coach. Until June 2022, two out of five patients managed to secure job positions (40.0%). Despite our efforts to improve employment with the instituted remedial strategy, we still fail to reach the minimum standard set by ministry. Future plan will focus on tailoring individual interests to a specific set of skills that match industrial expectation prior to seeking employment. Additionally, enhancing public education using social media may foster better inclusion of psychiatric patients and social acceptance.
A bite by the Twin-Barred Tree Snake, Chrysopelea pelias (Linnaeus, 1758)

Ismail AK, Weinstein SA, Auliya M, Sabardin DM, Herbosa TJ, Saiboon IM, et al.

Clin Toxicol (Phila), 2010 Mar;48(3):222-6.
PMID: 20345298 DOI: 10.3109/15563650903550964

The Twin-Barred Tree Snake, Chrysopelea pelias, is a colubrine that, like other members of the genus Chrysopelea, is able to glide in the arboreal strata. Little is known about the effects of its bite. This report is the first clinically documented bite by this relatively uncommon rear-fanged species.
Fulltext Drone for medical products transportation in maternal healthcare: A systematic review and framework for future research

Zailani MAH, Sabudin RZAR, Rahman RA, Saiboon IM, Ismail A, Mahdy ZA

Medicine (Baltimore), 2020 Sep 04;99(36):e21967.
PMID: 32899033 DOI: 10.1097/MD.0000000000021967

INTRODUCTION: Medical products transportation has become an important research topic requiring multidisciplinary collaboration among experts in medicine, engineering, and health economics. Current modes of transportation are unable to overcome the limited settings in maternal healthcare, particularly during the event of obstetric emergencies. The drone is a promising medical product aerial transportation (MedART) that holds an enormous potential for delivery of medical supplies in the healthcare system. We conducted a systematic review to examine scientific evidence of positive impact of drone transportation on maternal health.
METHODS: The following electronic databases were searched from inception to July 2019: ScienceDirect, PubMed, and EMBASE. The report was made in accordance with the principles of PRISMA guidelines. The search terms used were related to drones including unmanned aerial vehicle (UAV) and unmanned aerial system (UAS), and related to obstetric/maternal including obstetric emergencies and postpartum hemorrhage. Studies were selected if the intervention used were drones, and if any direct or indirect maternal health indicators were reported. Meta-analysis was not done throughout the study in view of the anticipated heterogeneity of each study.
RESULTS: Our initial search yielded a total of 244 relevant publications, from which 236 were carried forward for a title and abstract screening. After careful examination, only two were included for systematic synthesis. Among the reasons for exclusion were irrelevance to maternal health purpose, and irrelevance to drone applications in healthcare. An updated search yielded one additional study that was also included. Overall, two studies assessed drones for blood products delivery, and one study used drones to transport blood samples.
CONCLUSION: A significant deficiency was found in the number of reported studies analyzing mode of medical products transportation and adaptation of drones in maternal healthcare. Future drone research framework should focus on maternal healthcare-specific drone applications in order to reap benefits in this area.
Fulltext Investigation of the synergistic effect of nonionic surfactants on emulsion resolution using response surface methodology

Raya SA, Saaid IM, Mohd Aji AQ, A Razak AA

RSC Adv, 2022 Oct 27;12(48):30952-30961.
PMID: 36349040 DOI: 10.1039/d2ra04816g

The production of crude oil is always accompanied by water production, which may create severe separation problems. It is important to understand the stabilization mechanism and parameters contributing to the formation of emulsion, specifically the synergy mixing of surfactants. These factors have not been studied primarily in previous studies. The main objective of the current work was to assess the influence of synergy mixing of nonionic surfactants, sorbitan monooleate (hexitol) and polysorbate 80 (glycol), which are mainly affecting the stability of oil-in-water emulsions. Several factors, such as the mixing rate, mixing time, and aging time of the studied emulsions were also investigated. Response surface methodology (RSM), and central composite design (CCD) were employed to design the experiments. Emulsion stability was measured through a static bottle test over a range of time (1-7 days) at a temperature of 60 °C. A model was established with a coefficient of determination value at 0.8814 and the highest emulsion stability achieved was 42.83%. The least water separation was observed at 0.5 v/v% hexitol, 1.5 v/v% glycol, 15 000 rpm mixing rate in 5 minutes, and seven-day ageing time to achieve ∼41.56% emulsion stability. The minimum emulsion stability of ∼25.0% was observed using 0.5 v/v% of sorbitan monooleate and polysorbate 80 at 5000 rpm of mixing rate in 15 min and under seven days of observation. The results also revealed that the mixing time and ageing time do not affect the stability of the prepared emulsions. Hexitol, mixing rate, synergy mixing of nonionic surfactants and polysorbate 80, and mixing speed significantly influence emulsion stability. The R 2 value of 88.14% verified that the model is well-fitted and the optimal values for the input variables were successfully obtained using RSM.
Fulltext Eliminating aluminum toxicity in an acid sulfate soil for rice cultivation using plant growth promoting bacteria

Panhwar QA, Naher UA, Radziah O, Shamshuddin J, Razi IM

Molecules, 2015 Feb 20;20(3):3628-46.
PMID: 25710843 DOI: 10.3390/molecules20033628

Aluminum toxicity is widely considered as the most important limiting factor for plants growing in acid sulfate soils. A study was conducted in laboratory and in field to ameliorate Al toxicity using plant growth promoting bacteria (PGPB), ground magnesium limestone (GML) and ground basalt. Five-day-old rice seedlings were inoculated by Bacillus sp., Stenotrophomonas maltophila, Burkholderia thailandensis and Burkholderia seminalis and grown for 21 days in Hoagland solution (pH 4.0) at various Al concentrations (0, 50 and 100 μM). Toxicity symptoms in root and leaf were studied using scanning electron microscope. In the field, biofertilizer (PGPB), GML and basalt were applied (4 t·ha-1 each). Results showed that Al severely affected the growth of rice. At high concentrations, the root surface was ruptured, leading to cell collapse; however, no damages were observed in the PGPB inoculated seedlings. After 21 days of inoculation, solution pH increased to >6.0, while the control treatment remained same. Field study showed that the highest rice growth and yield were obtained in the bio-fertilizer and GML treatments. This study showed that Al toxicity was reduced by PGPB via production of organic acids that were able to chelate the Al and the production of polysaccharides that increased solution pH. The release of phytohormones further enhanced rice growth that resulted in yield increase.
Severity of Malaria cases reported in urban and rural hospitals in Malaysia

Nimir AR, Isa NH, Eugene CB, Ghauth IM, Salleh FM, Rahman RA

Southeast Asian J Trop Med Public Health, 2006 Sep;37(5):831-7.
PMID: 17333723

The age distribution, types of infection and clinical patterns of malaria were compared in patients admitted to an urban and a rural hospital. Analysis of the cases seen in urban setting characteristically indicated a relatively low transmission rate of the disease, whereas the mean inoculation rate in patients from the rural hospital was found to be at least twenty folds higher. Plasmodium vivax was the predominant causative species in the urban hospital (p = 0.01), infecting mostly adult (p = 0.001) males (p = 0.01). The geometric mean parasite count at 3432/microl among the urban patients was significantly higher than that in the rural patients at 1422/microl (p = 0.04). Coma and death were more common among the cases seen in the urban hospital (p = 0.003), while severe anemia was the significant complication in the rural setting. Overall, the provisional diagnosis of malaria was relatively low in the urban hospital (p = 0.02). The results from this study highlighted the need to define the extent of malaria in urban areas. This report attempts to identify the non-climatic determinants of the infection and, furthermore, to provide a more informed basis to describe the burden of the disease.
Fulltext Role of accumulated calcium in alleviating aluminum injury in wheat plants

Hossain MA, Ashrafuzzaman M, Hossain AK, Ismail MR, Koyama H

ScientificWorldJournal, 2014;2014:457187.
PMID: 24701169 DOI: 10.1155/2014/457187

Aluminum (Al) sensitive wheat cultivar kalyansona was grown for 14 d in a range of Ca solution (125, 625, and 2500 μM) plus other nutrients without Al. At 14 d after Ca treatment, half of these plants were harvested (H1), and the rest of the plants were exposed to 100 μM Al for additional 6 d and harvested (H2). Severe Al injury was found only in the plants with the lowest supply of Ca before Al treatment. Aluminum concentration in the apoplastic fluid was very high at 125 μM Ca probably because the plasma membrane of some of the cells was destroyed due to the attack of 100 μM Al. Aluminum content in roots decreased with increasing supply of Ca before Al treatment. Calcium content decreased drastically at harvest (H2) in the plants with 100 μM Al. Under Al stress conditions, the plant responded to Al in different ways due to not only the different Ca supply but also the variation of Ca content in the plant tissues. Actually, the plants having the largest Ca content in the roots before Al treatment can receive less Al injury during Al treatment. To substantiate this idea, a companion study was conducted to investigate the effects of 2500 μM Ca supply during, before, and after 100 μM Al treatment on root growth. The results indicated clearly that exogenous Ca supply before Al treatment is able to alleviate Al injury but less effective than Ca supply during Al treatment.
Fulltext Grain sterility in relation to dry mass production and distribution in rice (Oryza sativa L.)

Puteh AB, Mondal MM, Ismail MR, Latif MA

Biomed Res Int, 2014;2014:302179.
PMID: 24895563 DOI: 10.1155/2014/302179

The experiment was conducted to investigate potential causes of grain sterility in widely cultivated rice variety in Malaysia, MR219 and its two mutant lines (RM311 and RM109) by examining the source-sink relations. RM311 produced increased dry matter yield both at heading and maturity and also showed higher grain yield with greater proportion of grain sterility than the other two genotypes (RM109 and MR219) resulting in the lowest harvest index (49.68%). In contrast, harvest index was greater in RM109 (53.34%) and MR219 (52.76%) with less grain sterility percentage than MR311 indicating that dry matter partitioning to economic yield was better in RM109 and MR219 than in MR311. Results indicated that dry matter allocation per spikelet from heading to maturity was important for reducing grain sterility in rice. The greater above-ground crop dry matter per spikelet was observed in RM109 and MR219 as compared to high dry matter producing genotype; RM311 implies that poor grain filling may not have resulted from dry matter production or source limitation. These findings suggest that grain sterility or poor grain filling in rice is the result of poor translocation and partitioning of assimilates into grains (sink) rather than of limited biomass production or source limitation.
Sleep habits, food intake, and physical activity levels in normal and overweight and obese Malaysian children

Firouzi S, Poh BK, Ismail MN, Sadeghilar A

Obes Res Clin Pract, 2014 Jan-Feb;8(1):e70-8.
PMID: 24548579 DOI: 10.1016/j.orcp.2012.12.001

This study aimed to determine the association between sleep habits (including bedtime, wake up time, sleep duration, and sleep disorder score) and physical characteristics, physical activity level, and food pattern in overweight and obese versus normal weight children.
Physical activity, fitness and the energy cost of activities: implications for obesity in children and adolescents in the tropics

Lau XC, Chong KH, Poh BK, Ismail MN

Adv. Food Nutr. Res., 2013;70:49-101.
PMID: 23722094 DOI: 10.1016/B978-0-12-416555-7.00002-3

The tropics cover a large section of the world in which both developed and developing countries are situated. Rapid socioeconomic development, modernization, urbanization, and globalization have affected both the food market and physical activity (PA), which in turn have propelled the obesity epidemic in the tropics. There is growing concern that overweight and obesity are emerging as major health problems among children and adolescents in the tropics, despite the fact that undernutrition still exists in many of these countries. Physical inactivity, a low metabolic rate, and lack of physical fitness (PF) have been linked to overweight and obesity. Moreover, PF in several tropical countries is declining, and these changes may be a threat to future health, as low PA and PF levels are important risk factors for noncommunicable chronic diseases. Previous studies have reported that the relationships among PA, PF, overweight, and obesity are inconsistent and inconclusive. There is no indication that variances in the energy cost of physical activities lead to obesity. Despite a lack of definite evidence to prove a causal relationship, there is enough certainty that physical inactivity and low fitness levels are linked to overweight and obesity. Hence, people living in tropical countries need to be encouraged to lead a healthier lifestyle by increasing their PA levels and reducing sedentary behaviors to prevent overweight or obesity.
Fulltext Evaluation of antioxidant properties and mineral composition of Purslane (Portulaca oleracea L.) at different growth stages

Uddin MK, Juraimi AS, Ali ME, Ismail MR

Int J Mol Sci, 2012;13(8):10257-67.
PMID: 22949859 DOI: 10.3390/ijms130810257

The main objective of this research was to appraise the changes in mineral content and antioxidant attributes of Portulaca oleracea over different growth stages. The antioxidant activity was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). DPPH scavenging (IC(50)) capacity ranged from 1.30 ± 0.04 to 1.71 ± 0.04 mg/mL, while the ascorbic acid equivalent antioxidant activity (AEAC) values were 229.5 ± 7.9 to 319.3 ± 8.7 mg AA/100 g, total phenol content (TPC) varied from 174.5 ± 8.5 to 348.5 ± 7.9 mg GAE/100 g. AAC 60.5 ± 2.1 to 86.5 ± 3.9 mg/100 g and FRAP 1.8 ± 0.1 to 4.3 ± 0.1 mg GAE/g. There was good correlation between the results of TPC and AEAC, and between IC(50) and FRAP assays (r(2) > 0.9). The concentrations of Ca, Mg, K, Fe and Zn increased with plant maturity. Calcium (Ca) was negatively correlated with sodium (Na) and chloride (Cl), but positively correlated with magnesium (Mg), potassium (K), iron (Fe) and zinc (Zn). Portulaca olerecea cultivars could be used as a source of minerals and antioxidants, especially for functional food and nutraceutical applications.
Fulltext Recovery of Palm Oil and Valuable Material from Oil Palm Empty Fruit Bunch by Sub-critical Water

Ahmad Kurnin NA, Shah Ismail MH, Yoshida H, Izhar S

J Oleo Sci, 2016;65(4):283-9.
PMID: 27041513 DOI: 10.5650/jos.ess15209

Oil palm empty fruit bunch (EFB) is one of the solid wastes produced in huge volume by palm oil mill. Whilst it still contains valuable oil, approximately 22.6 million tons is generated annually and treated as solid waste. In this work, sub-critical water (sub-cw) was used to extract oil, sugar and tar from spikelet of EFB. The spikelet was treated with sub-cw between 180-280°C and a reaction time of 2 and 5 minutes. The highest yield of oil was 0.075 g-oil/g-dry EFB, obtained at 240°C and reaction time of 5 minutes. Astonishingly, oil that was extracted through this method was 84.5% of that obtained through Soxhlet method using hexane. Yield of oil extracted was strongly affected by the reaction temperature and time. Higher reaction temperature induces the dielectric constant of water towards the non-polar properties of solvent; thus increases the oil extraction capability. Meanwhile, the highest yield of sugar was 0.20 g-sugar/g-dry EFB obtained at 220°C. At this temperature, the ion product of water is high enough to enable maximum sub-critical water hydrolysis reaction. This study showed that oil and other valuable material can be recovered using water at sub-critical condition, and most attractive without the use of harmful organic solvent.
Fulltext A newton cooperative genetic algorithm method for in silico optimization of metabolic pathway production

Ismail MA, Deris S, Mohamad MS, Abdullah A

PLoS One, 2015;10(5):e0126199.
PMID: 25961295 DOI: 10.1371/journal.pone.0126199

This paper presents an in silico optimization method of metabolic pathway production. The metabolic pathway can be represented by a mathematical model known as the generalized mass action model, which leads to a complex nonlinear equations system. The optimization process becomes difficult when steady state and the constraints of the components in the metabolic pathway are involved. To deal with this situation, this paper presents an in silico optimization method, namely the Newton Cooperative Genetic Algorithm (NCGA). The NCGA used Newton method in dealing with the metabolic pathway, and then integrated genetic algorithm and cooperative co-evolutionary algorithm. The proposed method was experimentally applied on the benchmark metabolic pathways, and the results showed that the NCGA achieved better results compared to the existing methods.
Characterization of S1 gene sequence variations of attenuated QX-like and variant infectious bronchitis virus strains and the pathogenicity of the viruses in specific-pathogen-free chickens

Ismail MI, Wei TS, Hair-Bejo M, Omar AR

Arch Virol, 2020 Dec;165(12):2777-2788.
PMID: 32964293 DOI: 10.1007/s00705-020-04812-2

Besides the vaccine strains, the Malaysian variant (MV) and QX-like are the predominant IBVs detected on commercial poultry farms. These two virus strains are distinct based on genomic and pathogenicity studies. In this study, we determined the sequence of the S1 gene and compared the pathogenicity of serial passage 70 (P70) of Malaysian QX-like (QX/P70) and MV (MV/P70) strains with that of their respective wild-type viruses. The nucleotide and amino acid sequences of the complete S1 genes of QX/P70 and MV/P70 showed 1.4 to 1.6% and 3.0 to 3.3% variation, respectively, when compared to the wild-type virus. Most of the mutations were insertions and substitutions in the hypervariable regions (HVRs), primarily in HVR 3. Furthermore, selection pressure analysis showed that both viruses are under purifying selection. A pathogenicity study in specific-pathogen-free (SPF) chickens showed a reduction in respiratory and kidney lesions in chickens inoculated with MV/P70, but not with QX/P70, when compared to the respective wild-type viruses. However, MV/P70 is still pathogenic and can cause ciliary damage. In conclusion, the MV IBV strain is more responsive than the QX-like IBV strain following the attenuation process used for the development of a live attenuated IBV vaccine.
The detrimental effects of the COVID-19 pandemic on domestic violence against women

Noman AHM, Griffiths MD, Pervin S, Ismail MN

J Psychiatr Res, 2021 02;134:111-112.
PMID: 33383493 DOI: 10.1016/j.jpsychires.2020.12.057
Fulltext Dispersive Liquid-Liquid Microextraction (DLLME) and LC-MS/MS Analysis for Multi-Mycotoxin in Rice Bran: Method Development, Optimization and Validation

Salim SA, Sukor R, Ismail MN, Selamat J

Toxins (Basel), 2021 04 15;13(4).
PMID: 33920815 DOI: 10.3390/toxins13040280

Rice bran, a by-product of the rice milling process, has emerged as a functional food and being used in formulation of healthy food and drinks. However, rice bran is often contaminated with numerous mycotoxins. In this study, a method to simultaneous detection of aflatoxins (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), deoxynivalenol (DON), fumonisins (FB1 and FB2), sterigmatocystin (STG), T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and zearalenone (ZEA) in rice bran was developed, optimized and validated using dispersive liquid-liquid microextraction (DLLME) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In DLLME, using a solvent mixture of methanol/water (80:20, v/v) as the dispersive solvent and chloroform as the extraction solvent with the addition of 5% salt improved the extraction recoveries (63-120%). The developed method was further optimized using the response surface methodology (RSM) combined with Box-Behnken Design (BBD). Under the optimized experimental conditions, good linearity was obtained with a correlation coefficient (r2) ≥ 0.990 and a limit of detection (LOD) between 0.5 to 50 ng g-1. The recoveries ranged from 70.2% to 99.4% with an RSD below 1.28%. The proposed method was successfully applied to analyze multi-mycotoxin in 24 rice bran samples.
Fulltext Novel Approach to the Treatment of Gypseous Soil-Induced Ettringite Using Blends of Non-Calcium-Based Stabilizer, Ground Granulated Blast-Furnace Slag, and Metakaolin

Ehwailat KIA, Mohamad Ismail MA, Ezreig AMA

Materials (Basel), 2021 Sep 10;14(18).
PMID: 34576422 DOI: 10.3390/ma14185198

Gypseous soil is one type of expansive soil that contains a sufficient amount of sulphate. Cement and lime are the most common methods of stabilizing expansive soil, but the problem is that lime-treated gypseous soil normally fails in terms of durability due to the formation of ettringite, a highly deleterious compound. Moisture ingress causes a significant swelling of ettringite crystals, thereby causing considerable damage to structures and pavements. This study investigated the suitability of various materials (nano-Mg oxide (M), metakaolin (MK), and ground granulated blast-furnace slag (GGBS)) for the stabilization of gypseous soil. The results showed soil samples treated with 20% M-MK, M-GGBS, and M-GGBS-MK to exhibit lower swelling rates (<0.01% change in volume) compared to those treated with 10% and 20% of lime after 90 days of curing. However, soil samples stabilized with 10% and 20% binder of [(M-MK), (M-GGBS), and (M-GGBS-MK)] exhibited higher strengths after 90 days of soaking (ranging from 0.96-12.8 MPa) compared to those stabilized with 10% and 20% lime. From the morphology studies, the SEM and EDX analysis evidenced no formation of ettringite in the samples stabilized with M-MK-, M-GGBS-, and M-GGBS-MK. These results demonstrate the suitability of M-MK, M-GGBS, and M-GGBS-MK as effective agents for the stabilization of gypseous soil.
Unrestrictive identification of post-translational modifications in Hevea brasiliensis latex

Habib MAH, Gan CY, Abdul Latiff A, Ismail MN

Biochem. Cell Biol., 2018 12;96(6):818-824.
PMID: 30058361 DOI: 10.1139/bcb-2018-0020

The natural rubber latex extracted from the bark of Hevea brasiliensis plays various important roles in modern society. Post-translational modifications (PTMs) of the latex proteins are important for the stability and functionality of the proteins. In this study, latex proteins were acquired from the C-serum, lutoids, and rubber particle layers of latex without using prior enrichment steps; they were fragmented using collision-induced dissociation (CID), higher-energy collisional dissociation (HCD), and electron-transfer dissociation (ETD) activation methods. PEAKS 7 were used to search for unspecified PTMs, followed by analysis through PTM prediction tools to crosscheck both results. There were 73 peptides in 47 proteins from H. brasiliensis protein sequences derived from UniProtKB were identified and predicted to be post-translationally modified. The peptides with PTMs identified include phosphorylation, lysine acetylation, N-terminal acetylation, hydroxylation, and ubiquitination. Most of the PTMs discovered have yet to be reported in UniProt, which would provide great assistance in the research of the functional properties of H. brasiliensis latex proteins, as well as being useful biomarkers. The data are available via the MassIVE repository with identifier MSV000082419.
Assessing the comparative advantage of broiler production in Peninsular Malaysia using policy analysis matrix

Benalywa ZA, Ismail MM, Shamsudin MN, Yusop Z

Trop Anim Health Prod, 2019 Feb;51(2):321-327.
PMID: 30112733 DOI: 10.1007/s11250-018-1690-8

Broiler meat is the largest and cheapest protein source in Malaysia. Using the policy analysis matrix (PAM), this study examines the comparative advantage of broiler production in Peninsular Malaysia. Three hundred and ten farms in Peninsular Malaysia were involved in a field survey. The results of the domestic resource cost (DRC) show that Malaysia has a comparative advantage in all scales of broiler production. Sensitivity analysis indicates that the changes in input prices have a significant effect on comparative advantage. Nonetheless, the industry should reduce its dependence on corn-based feed, which is expensive and has an unstable price, to increase competitiveness in further securing its comparative advantage.
Fulltext Effects of CNC Machining on Surface Roughness in Fused Deposition Modelling (FDM) Products

Lalegani Dezaki M, Mohd Ariffin MKA, Ismail MIS

Materials (Basel), 2020 Jun 08;13(11).
PMID: 32521663 DOI: 10.3390/ma13112608

Fused deposition modelling (FDM) opens new ways across the industries and helps to produce complex products, yielding a prototype or finished product. However, it should be noted that the final products need high surface quality due to their better mechanical properties. The main purpose of this research was to determine the influence of computer numerical control (CNC) machining on the surface quality and identify the average surface roughness (Ra) and average peak to valley height (Rz) when the specimens were printed and machined in various build orientations. In this study, the study samples were printed and machined to investigate the effects of machining on FDM products and generate a surface comparison between the two processes. In particular, the block and complex specimens were printed in different build orientations, whereby other parameters were kept constant to understand the effects of orientation on surface smoothness. As a result, wide-ranging values of Ra and Rz were found in both processes for each profile due to their different features. The Ra values for the block samples, printed samples, and machined samples were 21, 91, and 52, respectively, whereas the Rz values were identical to Ra values in all samples. These results indicated that the horizontal surface roughness yielded the best quality compared to the perpendicular and vertical specimens. Moreover, machining was found to show a great influence on thermoplastics in which the surfaces became smooth in the machined samples. In brief, this research showed that build orientation had a great effect on the surface texture for both processes.

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