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Fulltext A computational fluid dynamics study of combustion and emission performance in an annular combustor of a jet engine

Zuber, M., Hisham, M.S.B., Nasir, N.A.M., Basri, A.A., Khader, S.M.A.

Pertanika Journal of Science & Technology, 2017;25(3):1019-1028.
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This paper is a Computational Fluid Dynamics (CFD) study of the performance of a jet engine annular
combustor that was subjected to various loading conditions. The aim is to comprehend the effect of
various genuine working conditions on ignition and emission performance. The numerical models utilized for fuel ignition is the feasible k-ω model for turbulent stream, species transport (aviation fuel and air) with eddy-dissipation reaction modelling and pollution model for nitrogen oxides (NOX) emission. The results obtained confirm the findings described in the literature.
The presence of aflatoxins and ochratoxin A in rice and rice products; and evaluation of dietary intake

Iqbal SZ, Asi MR, Hanif U, Zuber M, Jinap S

Food Chem, 2016 Nov 1;210:135-40.
PMID: 27211631 DOI: 10.1016/j.foodchem.2016.04.104

In present study aflatoxins (AFs) and ochratoxin A (OTA) were analysed in 208 samples of rice and products collected from central areas of Punjab, Pakistan. The analysis was carried out using HPLC equipped with fluorescence detector. The results have shown that 35% of the samples were found contaminated with AFs, out of which 19% and 24% samples were found to be above the European Union (EU) maximum content for AFB1 and total AFs, respectively. About 19% samples were found contaminated with OTA and 14% samples were found to be above the EU maximum content. The highest mean level of AFB1 and total AFs were found in brown rice samples i.e. 8.91 and 12.4μg/kg, respectively. However, white rice samples have shown the highest mean level of OTA (8.50μg/kg) with highest level of 24.9μg/kg. The high mean dietary exposure 22.2 and 24.2ngkg(-1)bwday(-1) to AFB1 and OTA, respectively poses significant health hazard for local population.
Fulltext Fluid Structure Interaction on Paravalvular Leakage of Transcatheter Aortic Valve Implantation Related to Aortic Stenosis: A Patient-Specific Case

Basri AA, Zuber M, Basri EI, Zakaria MS, Aziz AFA, Tamagawa M, et al.

Comput Math Methods Med, 2020;2020:9163085.
PMID: 32454886 DOI: 10.1155/2020/9163085

This study investigated the impact of paravalvular leakage (PVL) in relation to the different valve openings of the transcatheter aortic valve implantation (TAVI) valve using the fluid structure interaction (FSI) approach. Limited studies were found on the subject of FSI with regards to TAVI-PVL condition, which involves both fluid and structural responses in coupling interaction. Hence, further FSI simulation with the two-way coupling method is implemented to investigate the effects of hemodynamics blood flow along the patient-specific aorta model subjected to the interrelationship between PVL and the different valve openings using the established FSI software ANSYS 16.1. A 3D patient-specific aorta model is constructed using MIMICS software. The TAVI valve identical to Edward SAPIEN XT 26 (Edwards Lifesciences, Irvine, California), at different Geometrical Orifice Areas (GOAs), is implanted into the patient's aortic annulus. The leaflet opening of the TAVI valve is drawn according to severity of GOA opening represented in terms of 100%, 80%, 60%, and 40% opening, respectively. The result proved that the smallest percentage of GOA opening produced the highest possibility of PVL, increased the recirculatory flow proximally to the inner wall of the ascending aorta, and produced lower backflow velocity streamlines through the side area of PVL region. Overall, 40% GOA produced 89.17% increment of maximum velocity magnitude, 19.97% of pressure drop, 65.70% of maximum WSS magnitude, and a decrement of 33.62% total displacement magnitude with respect to the 100% GOA.
Fulltext Parametric Study and Experimental Investigations of a Single Crank-Slotted Dual Lever Mechanism for MAV Flapping Actuation

Singh S, Muralidharan AK, Radhakrishnan J, Zuber M, Basri AA, Mazlan N, et al.

Biomimetics (Basel), 2022 Nov 21;7(4).
PMID: 36412736 DOI: 10.3390/biomimetics7040208

Insect RoboFlyers are interesting and active focuses of study but producing high-quality flapping robots that replicate insect flight is challenging., due to the dual requirement of both a sophisticated transmission mechanism with light weight and minimal intervening connections. This innovative mechanism was created to address the need for a producible structure that is small in size, small in mass, and has reduced design linkages. The proposed Single Crank-Slotted Dual Lever (SC-SDL) mechanism transforms rotational motion into specific angular motion at different velocities for each of its two strokes, i.e., the forward stroke and the return stroke. The discovery of a lag between the left and right lever motions in our design mechanism-I leads us to the conclusion that the flapping is asymmetric. To eliminate the position lag, the design has been altered, and a new design mechanism-II has been developed. Comparative kinematic analysis of both design systems is performed using simulations. Two-dimensional analysis of the base ornithopter configuration using ANSYS FLUENT yielded deeper insights regarding the influence of varying flapping frequency on critical flow metrics regarding adequate lift and thrust. For a flapping frequency of 24 Hz, adequate lift generation was achieved with minimal flow disturbances and wake interactions. Averaged dual wing estimations were made as part of the CFD study, which showed similar agreements. To validate the estimations, experimental tests were performed over the design mechanism-II configuration.
Nasal airflow comparison in neonates, infant and adult nasal cavities using computational fluid dynamics

Corda JV, Shenoy BS, Ahmad KA, Lewis L, K P, Khader SMA, et al.

Comput Methods Programs Biomed, 2022 Feb;214:106538.
PMID: 34848078 DOI: 10.1016/j.cmpb.2021.106538

BACKGROUND AND OBJECTIVE: Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated.
METHODS: Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified.
RESULTS: This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults.
CONCLUSIONS: The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.
Comparison of microparticle transport and deposition in nasal cavity of three different age groups

Valerian Corda J, Shenoy BS, Ahmad KA, Lewis L, K P, Rao A, et al.

Inhal Toxicol, 2024 Jan;36(1):44-56.
PMID: 38343121 DOI: 10.1080/08958378.2024.2312801

Objective: The nasal cavity effectively captures the particles present in inhaled air, thereby preventing harmful and toxic pollutants from reaching the lungs. This filtering ability of the nasal cavity can be effectively utilized for targeted nasal drug delivery applications. This study aims to understand the particle deposition patterns in three age groups: neonate, infant, and adult.Materials and methods: The CT scans are built using MIMICS 21.0, followed by CATIA V6 to generate a patient-specific airway model. Fluid flow is simulated using ANSYS FLUENT 2021 R2. Spherical monodisperse microparticles ranging from 2 to 60 µm and a density of 1100 kg/m3 are simulated at steady-state and sedentary inspiration conditions.Results: The highest nasal valve depositions for the neonate are 25% for 20 µm, for infants, 10% for 50 µm, 15% for adults, and 15% for 15 µm. At mid nasal region, deposition of 15% for 20 µm is observed for infant and 8% for neonate and adult nasal cavities at a particle size of 10 and 20 µm, respectively. The highest particle deposition at the olfactory region is about 2.7% for the adult nasal cavity for 20 µm, and it is <1% for neonate and infant nasal cavities.Discussion and conclusions: The study of preferred nasal depositions during natural sedentary breathing conditions is utilized to determine the size that allows medication particles to be targeted to specific nose regions.
Effectiveness of low to moderate potency topical corticosteroids for phimosis resolution in children: results of a network meta-analysis

Shanmugham S, Lee EL, Kumar S, Zuber M, Noreen N, Smales FC, et al.

Int Urol Nephrol, 2024 Aug 16.
PMID: 39150601 DOI: 10.1007/s11255-024-04184-5

PURPOSE: The use of topical corticosteroids (TCSs) has become an efficient, less-invasive treatment for phimosis. Whether any significant difference in efficacy exists between TCSs based on their potency is unclear.
METHODS: Electronic databases were searched up to March 2024 for randomised controlled trials (RCTs) comparing the use of any type or concentration of TCSs with placebo or no treatment in boys with any degree of physician diagnosed phimosis. A random-effects network meta-analysis (NMA) using a consistency model within a frequentist approach was employed. The primary outcome was partial or complete resolution of phimosis reported as a pooled risk ratio (RR) with 95% CI. Relative ranking was assessed with surface under the cumulative ranking curve (SUCRA) probabilities.
RESULTS: Seventeen RCTs, containing 2057 participants were identified. NMA suggested that, compared with control, the high (RR 3.19 (95% CI 1.42 to 7.16), moderate (RR 2.68 (95% CI 1.87 to 3.83) and low (RR 3.05 (95% CI 1.63 to 5.71) potency TCSs statistically significantly increased complete or partial clinical resolution of phimosis. The SUCRA plot revealed that high potency (SUCRA = 0.76) was ranked first followed by low and moderate TCSs. When we assessed comparative efficacy among TCSs based on potency, none of the classes were superior to others. The certainty of the evidence for an effect of moderate potent TCSs was that of moderate GRADE quality.
CONCLUSION: Moderate to low potency TCSs are of comparable therapeutic effect in the treatment of phimosis to that of highly potent formulations. More high-quality RCTs are warranted.
Efficacy of antidepressants in functional dyspepsia: Systematic review and meta-analysis with trial sequential analysis of randomized controlled trials

Shanmugham S, Zuber M, Chan JE, Kumar S, Ching SM, Lee YY, et al.

Indian J Gastroenterol, 2024 Aug 24.
PMID: 39180628 DOI: 10.1007/s12664-024-01648-5

INTRODUCTION: The beneficial effects of using antidepressants in improving functional dyspepsia (FD) symptoms have been reported in previous meta-analyses; however, the results have not been conclusive. The aim was to perform an updated meta-analysis coupled with trial sequential analysis (TSA) to assess the efficacy of the use of any antidepressants in the treatment of FD in adults.
METHODS: Electronic databases were searched up to March 2024 for randomized controlled trials (RCTs) recruiting adults with FD. Data of overall symptoms improved between the antidepressants and placebo groups was pooled to obtain risk ratio (RR) employing the random-effects model. The effect of random errors was evaluated with TSA. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the certainty of evidence. Analyses were performed using STATA version 16.0.
RESULTS: Nine RCTs with 924 patients met the eligible criteria. The RRs of FD symptoms improving with any antidepressants, tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors were (n = 9, RR = 1.30 [95% CI, 1.02-1.67]), (n = 5, RR = 1.41 [95% CI, 1.07-1.85]) and (n = 2, RR = 0.97 [95% CI, 0.72-1.29]), respectively. TSA demonstrated conclusive evidence for the beneficial effect of TCAs. The number needed to treat (NNT) with any depressants and TCAs were 11 (95% CI, 7-36) and 6 (95% CI, 4-15), respectively. The certainty of the evidence for an effect of TCAs was that of moderate GRADE quality. The benefit, however, was limited to the western population (n = 3, RR = 1.43 [95% CI, 1.04-1.96]) and did not extend to the Asian population (n = 2, RR = 1.32 [95% CI, 0.75-2.32]). Conversely, antidepressant-using patients experienced adverse events more frequently. However, no statistically significant association was found between TCAs and any adverse events (n = 3; RR = 1.36 [95% CI, 0.91-2.04]).
CONCLUSION: Evidence was obtained suggesting TCAs can be an effective alternative in the treatment of FD, but more evidence from high-quality large trials is required to support their use, especially in the Asian population.