Displaying publications 301 - 320 of 1883 in total

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  1. Glazier PS, Mehdizadeh S
    Sports Med, 2019 Feb;49(2):171-176.
    PMID: 30511347 DOI: 10.1007/s40279-018-1030-1
    This paper evaluates the effectiveness of, and highlights issues with, conventional paradigms in applied sports biomechanics research and comments on their capacity to optimise techniques of individual athletes. In empirical studies, group-based analyses often mask variability between athletes and only permit probabilistic 'in general' or 'on average' statements that may not be applicable to specific athletes. In individual-based analyses, performance parameters typically exhibit a small range and a flat response over iterative performance trials, making establishing associations between performance parameters and the performance criterion problematic. In theoretical studies, computer simulation modelling putatively enables athlete-specific optimum techniques to be identified, but given each athlete's unique intrinsic dynamics, it is far from certain that these optimum techniques will be attainable, particularly under the often intense psychological pressures of competition, irrespective of the volume of practice undertaken. Sports biomechanists and coaching practitioners are advised to be more circumspect with regard to interpreting the results of applied sports biomechanics research and have greater awareness of their assumptions and limitations, as inappropriate interpretation of results may have adverse consequences for performance and injury.
    Matched MeSH terms: Pressure
  2. Mohd Radzuan NA, Ismail NF, Fadzly Md Radzi MK, Razak ZB, Tharizi IB, Sulong AB, et al.
    Polymers (Basel), 2019 Oct 17;11(10).
    PMID: 31627431 DOI: 10.3390/polym11101707
    To date, the mechanical performance of kenaf composites is still unsatisfied in term of its mechanical performance. Therefore, research focuses on kenaf composites fabrication through the selection of polymer resin, including epoxy, polypropylene, and polylactic acid. The incorporated kenaf fibre at 10 wt % to 40 wt % loadings was conducted using injection and a compression moulding process. The compressed materials indicated high tensile strength at 240 MPa compared to inject materials (60 MPa). Significant improvement on impact strength (9 kJ/m2) was due to the unpulled-out fibre that dispersed homogenously and hence minimize the microcrack acquire. Meanwhile, high flexural strength (180 MPa) obtained by kenaf/epoxy composites due to the fibre orientate perpendicular to the loading directions, which improve its mechanical properties. The findings indicate that the kenaf fibre reinforced thermoset materials exhibit better mechanical properties as a function to the battery tray applications.
    Matched MeSH terms: Pressure
  3. Hassan M, Yahya A, Okamoto T
    In this paper, we report the effect of BaAl2O4 addition (0-30 wt. %) on power consumption and oxygen sensing response of hot-spots developed on short Er123 ceramic rods of around 12 mm length synthesized using standard solid-state reaction. All the sensor rods showed increase in output current with increasing voltage followed by sudden reduction in output current and appearance of hot spot. After appearance of hot spot, for each rod, output current was observed to decrease gradually with increasing voltage with the slope of the I-V curve gradually approaching zero. Output current after the hot spot formation showed sensitivity to oxygen partial pressure, pO2 between 1 to 100 kPa. Addition of 30 wt. % BaAl2O4 reduced the fluctuation of current and increased the sensitivity for pO2 below 10 kPa. In addition, overshoot current was also reduced and resulted in improvement of response time from around 10 s to 5 s. Our result also showed that minimum power consumption was significantly reduced in the Er123 rods with 30 wt. % BaAl2O4.
    Matched MeSH terms: Partial Pressure
  4. Liansheng Tang, Haitao Sang, Liqun Jiang, Yinlei Sun
    Sains Malaysiana, 2016;45:141-156.
    The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction (which has been widely used since the discipline of unsaturated soil mechanics was established). In fact, the concept of matrix suction is from soil science and reflects the water-absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which were not in conformity with the principle of effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: The effective cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: Soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of an unsaturated soil.
    Matched MeSH terms: Pressure
  5. Sinnathambi CM, Reem Ahmed Mohammed Ismail
    Sains Malaysiana, 2012;41:885-892.
    Taguchi orthogonal array design, a statistical software is applied to n-hexane reforming. The purpose is to identify the most significant process variable in reforming conditions favouring n-hexane conversion to high aromatics and isomers and low cracked and coke precursor reformate products. Actual experimental data were used for this study. Three process variables i.e. temperature, contact time and hydrogen partial pressure were investigated. From the study it was found that the contact time was the most critical operating parameter for n-hexane conversion followed by reaction temperature and hydrogen partial pressure. It was also noted that enhanced n-hexane reforming conversion can be achieved by operating the process at reaction temperature 723 K and contact time 7.1 min with a H2 partial pressure 300 kPa. For selectivity to aromatics and isomers lower contact time of 1.07 min with intermediate hydrogen partial pressure of 300 to 500 kPa operating at a reaction temperature of 723 K is most favourable.
    Matched MeSH terms: Partial Pressure
  6. NUR SURIANNI AHAMAD SUFFIN, ANASYIDA ABU SEMAN, ZUHAILAWATI HUSSAIN
    Sains Malaysiana, 2013;42:1755-1761.
    Aluminum foams were fabricated by sintering dissolution process (SDP) using sodium chloride (NaCl) as space holder. The compositions of space holder, used in this study were 40 and 60 wt. % with different dissolution times; 1, 2 and 3 h. The effect of different dissolution times on compressive behavior and energy absorption of foams were evaluated. The result showed that by increasing space holder and dissolution times, energy absorption capability increases. For aluminum foam contains 60 wt. % NaCl, longer dissolution times resulted in thinner cell wall and cell structure become more unstable which lead to lower plateau region.
    Matched MeSH terms: Pressure
  7. Chong MM, Chang SY, Noraiham Muhammad, Zulkifli Mord Rosli, Qumrul Ahsan
    Sains Malaysiana, 2014;43:959-966.
    Dry sliding wear of polyester hybrid composites containing carboxylic functionalized multi-walled carbon nanotubes (cNT) and microparticles, silica (Si02) was studied at different sliding distances. An attempt has been made to produce uniform dispersion of nano- and micro- particles in the test samples by ultrasonication. The tribological properties of the hybrid composites were performed by using pin-on-disc (POD) tester against grey cast iron countersurface. The dry sliding wear tests were carried out under pressure-velocity (pv) condition of 0.4 MPa and 4 m/s for total sliding distance of 28800 m and at an interval of every sliding distance of 3600 m, wear properties and behavior were studied. The samples containing 10 wt.% silica (microparticles) with and without CNT always show increase in coefficient of friction at the expense of wear rate. However, samples containing only ci'rr have the lowest wear rate with the increase in coefficient of friction. Sliding distance studies also provide the information on wear rates which were ever changing at different sliding distances whereas average coefficient of friction did not vary throughout the tests. SEM observations of wear surfaces showed different wear morphologies when reinforcement (cNT or Si02) incorporated into the composites either alone or in combination.
    Matched MeSH terms: Pressure
  8. Mehmood OU, Norzie Mustapha, Sharidan Shafie, Hayat T
    Sains Malaysiana, 2014;43:1109-1118.
    This research looks at the effects of partial slip on heat and mass transfer of peristaltic transport. The magnetohydrodynamic (MHD) flow of viscous fluid in a porous asymmetric channel has been considered. The exact solutions for the stream function, longitudinal pressure gradient, longitudinal velocity, shear stress, temperature and concentration fields are derived by adopting long wavelength and small Reynolds number approximations. The results showed that peristaltic pumping and trapping are reduced with increasing velocity slip parameter. Furthermore, temperature increases with increasing thermal slip parameter. Moreover, the concentration profile decreases with increasing porosity parameter, Schmidt number and concentration slip parameter. Comparisons with published results are found to be in good agreement.
    Matched MeSH terms: Pressure
  9. Khairiah Haji Badri, Muhammad Syukri Ngah
    Sains Malaysiana, 2015;44:861-867.
    An investigation on a batch production of palm kernel oil polyol (PKO-p) was conducted via esterification and condensation.
    The process design was thoroughly studied as a preliminary step for future upscaling. The process variables included
    necessity of vacuum pump, controlling of heating rate, recording the production time, nitrogen gas flow and agitator
    speed. About 250 mL PKO-p was successfully synthesized within 3 h. Vacuum pressure was applied to haul out moisture
    from the system. The control of heating rate and production time are vital to avoid sudden oxidation.
    Matched MeSH terms: Pressure
  10. Garcia-Martin R, González-Briones A, Corchado JM
    Sensors (Basel), 2019 May 25;19(10).
    PMID: 31130598 DOI: 10.3390/s19102390
    Due to fire protection regulations, a minimum number of fire extinguishers must be available depending on the surface area of each building, industrial establishment or workplace. There is also a set of rules that establish where the fire extinguisher should be placed: always close to the points that are most likely to be affected by a fire and where they are visible and accessible for use. Fire extinguishers are pressure devices, which means that they require maintenance operations that ensure they will function properly in the case of a fire. The purpose of manual and periodic fire extinguisher checks is to verify that their labeling, installation and condition comply with the standards. Security seals, inscriptions, hose and other seals are thoroughly checked. The state of charge (weight and pressure) of the extinguisher, the bottle of propellant gas (if available), and the state of all mechanical parts (nozzle, valves, hose, etc.) are also checked. To ensure greater safety and reduce the economic costs associated with maintaining fire extinguishers, it is necessary to develop a system that allows monitoring of their status. One of the advantages of monitoring fire extinguishers is that it will be possible to understand what external factors affect them (for example, temperature or humidity) and how they do so. For this reason, this article presents a system of soft agents that monitors the state of the extinguishers, collects a history of the state of the extinguisher and environmental factors and sends notifications if any parameter is not within the range of normal values.The results rendered by the SmartFire prototype indicate that its accuracy in calculating pressure changes is equivalent to that of a specific data acquisition system (DAS). The comparative study of the two curves (SmartFire and DAS) shows that the average error between the two curves is negligible: 8% in low pressure measurements (up to 3 bar) and 0.3% in high pressure (above 3 bar).
    Matched MeSH terms: Pressure
  11. Choy YW, Cheong I
    Family Physician, 1989;1:19-22.
    This study was carried out on 30 patients to: i) determine the efficacy of low dose captopril as monotherapy (with or without a diuretic) in the treatment of various grades of hypertension. ii) assess the quality of life of these patients 12 weeks after commencement of therapy. Our results showed that there was a sustained and significant fall in both mean systolic and diastolic blood pressure from 171.9 ± 24 to 150.5 ± 25 mm Hg and 109.0 ± 14 to 93.6 ± 15mmHg respectively (p<0.001). Improvement in quality of life was however not statistically significant (p<0.05). We concluded that low dose captopril used alone or in combination with a diuretic can be considered for the initial therapy of mild to moderate hypertension. The optimal dosage and the longterm benefits on quality of life need further evaluation in a larger series.
    Matched MeSH terms: Blood Pressure
  12. Sivalingam N, Bhagat S, Pereira R
    Family Physician, 1989;1:23-27.
    Matched MeSH terms: Blood Pressure
  13. Mohammed Falalu Hamza, Chandra MS, Zulkifli Merican Aljunid Merican, Hassan Soleimani, D. SK
    Sains Malaysiana, 2017;46:1641-1450.
    Foam flooding technique, commonly known as foam assisted water alternating gas method (FAWAG) has been identified as an effective chemical enhanced oil recovery (CEOR) technique. The ability of EOR-foam to sweep oil in low permeable zones makes it important displacement fluid in the oil industry. However, extreme reservoir conditions such as temperature, pressure and salinity have detrimental effects on the stability and the overall performance of the EOR-foam. Consequently, understanding foam stability and performance under different conditions is crucial for long term oil field application. This paper discusses the current status of the EOR-foam stability, performance and challenges from laboratory studies to field application perspective. The paper also highlights the knowledge gaps which require further research for successful field application.
    Matched MeSH terms: Pressure
  14. Norwahyu Jusoh, Lau KK, Yeong YF, Azmi M. Shariff
    Sains Malaysiana, 2016;45:1707-1714.
    The increasing demands of natural gas pushes energy industries to explore the reservoirs contain high CO2 concentration
    and impurities including heavy hydrocarbons. High efficiency of using membrane technology in CO2
    -natural gas separation
    has extended its potential application to offshore environment. Due to the limited studies related with the separation of
    CO2
    under offshore conditions, the present work has investigated the separation performance of a commercial membrane
    in removing bulk CO2
    from methane at elevated pressure condition. A wide range of offshore operating conditions
    including pressure from 10 to 50 bar, CO2
    concentration from 25 to 70% and temperature of 30o
    C, 40o
    C and 50o
    C were
    studied. High relative CO2 permeance and relative CO2
    /CH4
    selectivity were observed when the pressure and the CO2
    concentration increased. This work, therefore substantial is to bridge the gap and facilitates the application of membrane
    technology for offshore operating conditions.
    Matched MeSH terms: Pressure
  15. Zhang X, Chen X, Jin J, Gong M, He Q, Li S, et al.
    J Chromatogr Sci, 2021 Oct 29;59(10):941-948.
    PMID: 33728454 DOI: 10.1093/chromsci/bmab028
    Capilliposide B (CPS-B) and Capilliposide C (CPS-C), as the key components in Lysimachia capillipes Hemsl., increasingly aroused the interest and research concern of many researchers due to the good bioactivities. Nowadays, the reference standards of CPS-B and CPS-C yield were very limited. Due to the deficit of reference standards, the determination could be difficult to carry out, and the quality control and evaluation would be restrained afterwards. To solve this urgent problem, a quantitative analysis of multi-components by single-marker (QAMS) method was proposed and established based on high-performance liquid-chromatography tandem evaporative light-scattering detector. In this QAMS method, the content of the two bioactive components could be calculated by buddlejasaponin IV, which is applied as an external standard and readily obtained. And the methodological experiments were evaluated and indicated accuracy, stability and feasibility of this QAMS method. Therefore, in this study, this built method would properly meet the requirement of determination of CPS-B, CPS-C and quality control of the L. capillipes Hemsl. plant.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  16. Ang CYS, Chiew YS, Vu LH, Cove ME
    Comput Methods Programs Biomed, 2022 Mar;215:106601.
    PMID: 34973606 DOI: 10.1016/j.cmpb.2021.106601
    BACKGROUND: Spontaneous breathing (SB) effort during mechanical ventilation (MV) is an important metric of respiratory drive. However, SB effort varies due to a variety of factors, including evolving pathology and sedation levels. Therefore, assessment of SB efforts needs to be continuous and non-invasive. This is important to prevent both over- and under-assistance with MV. In this study, a machine learning model, Convolutional Autoencoder (CAE) is developed to quantify the magnitude of SB effort using only bedside MV airway pressure and flow waveform.

    METHOD: The CAE model was trained using 12,170,655 simulated SB flow and normal flow data (NB). The paired SB and NB flow data were simulated using a Gaussian Effort Model (GEM) with 5 basis functions. When the CAE model is given a SB flow input, it is capable of predicting a corresponding NB flow for the SB flow input. The magnitude of SB effort (SBEMag) is then quantified as the difference between the SB and NB flows. The CAE model was used to evaluate the SBEMag of 9 pressure control/ support datasets. Results were validated using a mean squared error (MSE) fitting between clinical and training SB flows.

    RESULTS: The CAE model was able to produce NB flows from the clinical SB flows with the median SBEMag of the 9 datasets being 25.39% [IQR: 21.87-25.57%]. The absolute error in SBEMag using MSE validation yields a median of 4.77% [IQR: 3.77-8.56%] amongst the cohort. This shows the ability of the GEM to capture the intrinsic details present in SB flow waveforms. Analysis also shows both intra-patient and inter-patient variability in SBEMag.

    CONCLUSION: A Convolutional Autoencoder model was developed with simulated SB and NB flow data and is capable of quantifying the magnitude of patient spontaneous breathing effort. This provides potential application for real-time monitoring of patient respiratory drive for better management of patient-ventilator interaction.

    Matched MeSH terms: Positive-Pressure Respiration
  17. Lim YP, Yahya N, Izaham A, Kamaruzaman E, Zainuddin MZ, Wan Mat WR, et al.
    Turk J Med Sci, 2018 Dec 12;48(6):1219-1227.
    PMID: 30541250 DOI: 10.3906/sag-1802-126
    Background/aim: Regional anesthesia for surgery is associated with increased anxiety for patients. This study aimed to compare the
    effect of propofol and dexmedetomidine infusion on perioperative anxiety during regional anesthesia.

    Materials and methods: Eighty-four patients were randomly divided into two groups receiving either study drug infusion. Anxiety
    score, level of sedation using the Bispectral Index and Observer’s Assessment of Alertness and Sedation, hemodynamic stability, and
    overall patient’s feedback on anxiolysis were assessed.

    Results: Both groups showed a significant drop in mean anxiety score at 10 and 30 min after starting surgery. Difference in median
    anxiety scores showed a significant reduction in anxiety score at the end of the surgery in the dexmedetomidine group compared to the
    propofol group. Dexmedetomidine and propofol showed a significant drop in mean arterial pressure in the first 30 min and first 10 min
    respectively. Both drugs demonstrated a significant drop in heart rate in the first 20 min from baseline after starting the drug infusion.
    Patients in the dexmedetomidine group (76.20%) expressed statistically excellent feedback on anxiolysis compared to patients in the
    propofol group (45.20%).

    Conclusion: Dexmedetomidine infusion was found to significantly reduce anxiety levels at the end of surgery compared to propofol
    during regional anesthesia.

    Matched MeSH terms: Arterial Pressure
  18. Rahman MNA, Zubir NSM, Leuveano RAC, Ghani JA, Mahmood WMFW
    Materials (Basel), 2014 Dec 02;7(12):7706-7721.
    PMID: 28788270 DOI: 10.3390/ma7127706
    The significant increase in metal costs has forced the electronics industry to provide new materials and methods to reduce costs, while maintaining customers' high-quality expectations. This paper considers the problem of most electronic industries in reducing costly materials, by introducing a solder paste with alloy composition tin 98.3%, silver 0.3%, and copper 0.7%, used for the construction of the surface mount fine-pitch component on a Printing Wiring Board (PWB). The reliability of the solder joint between electronic components and PWB is evaluated through the dynamic characteristic test, thermal shock test, and Taguchi method after the printing process. After experimenting with the dynamic characteristic test and thermal shock test with 20 boards, the solder paste was still able to provide a high-quality solder joint. In particular, the Taguchi method is used to determine the optimal control parameters and noise factors of the Solder Printer (SP) machine, that affects solder volume and solder height. The control parameters include table separation distance, squeegee speed, squeegee pressure, and table speed of the SP machine. The result shows that the most significant parameter for the solder volume is squeegee pressure (2.0 mm), and the solder height is the table speed of the SP machine (2.5 mm/s).
    Matched MeSH terms: Pressure
  19. 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.
    Matched MeSH terms: Pressure
  20. Raman P, Suliman NB, Zahari M, Kook M, Ramli N
    Eye (Lond), 2018 07;32(7):1183-1189.
    PMID: 29491486 DOI: 10.1038/s41433-018-0057-8
    OBJECTIVE: To assess the relationship between baseline intraocular pressure (IOP), blood pressure (BP) and ocular perfusion pressure (OPP), and the 5-year visual field progression in normal-tension glaucoma (NTG) patients.

    DESIGN: Prospective, longitudinal study.

    METHODS: Sixty-five NTG patients who were followed up for 5 years are included in this study. All the enrolled patients underwent baseline 24-h IOP and BP monitoring via 2-hourly measurements in their habitual position and were followed up for over 5 years with reliable VF tests. Modified Anderson criteria were used to assess VF progression. Univariable and multivariable analyses using Cox's proportional hazards model were used to identify the systemic and clinical risk factors that predict progression. Kaplan-Meier survival analyses were used to compare the time elapsed to confirmed VF progression in the presence or absence of each potential risk factor.

    RESULTS: At 5-year follow-up, 35.4% of the enrolled patients demonstrated visual field progression. There were statistically significant differences in the mean diastolic blood pressure (p  43.7 mmHg (log rank = 0.018).

    CONCLUSION: Diastolic parameters of BP and OPP were significantly lower in the NTG patients who progressed after 5 years. Low nocturnal DOPP is an independent predictor of glaucomatous visual field progression in NTG patients.

    Matched MeSH terms: Blood Pressure/physiology*; Intraocular Pressure/physiology*
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