Displaying publications 101 - 120 of 141 in total

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  1. Ahmad M, Roy RA
    Endod Dent Traumatol, 1994 Apr;10(2):71-6.
    PMID: 8062810
    The incidence of breakage of Piezon-Master ultrasonic K files were evaluated. Three groups of unused files were subjected to three treatments, namely; free vibration in air without irrigation, free vibration in root canal while minimizing contact with the wall of canal in the presence of irrigation and light filing in root canal with free flow of irrigation. Cavitation produced by files in contact and free of contact with a glass surface was examined in order to observe the relationship between cavitation defects and breakage. In addition, the fractured and unfractured files were examined under a scanning electron microscope for the presence of cavitation pits. The results indicated that more files broke in air. In water, a higher incidence of breakage occurred when files were allowed to freely vibrate while no breakage occurred when the files were used in filing. All files generated cavitation which resulted in pitting of their surfaces. However, it was considered unlikely that the pits contributed to fracture. Fatigue cracks which could be the result of the manufacturing process were observed at some of the corners of the cross sections of the fractured files and could be the main contributory factor to fracture.
    Matched MeSH terms: Equipment Failure
  2. Jong WL, Wong JH, Ung NM, Ng KH, Ho GF, Cutajar DL, et al.
    J Appl Clin Med Phys, 2014 Sep 08;15(5):4869.
    PMID: 25207573 DOI: 10.1120/jacmp.v15i5.4869
    In vivo dosimetry is important during radiotherapy to ensure the accuracy of the dose delivered to the treatment volume. A dosimeter should be characterized based on its application before it is used for in vivo dosimetry. In this study, we characterize a new MOSFET-based detector, the MOSkin detector, on surface for in vivo skin dosimetry. The advantages of the MOSkin detector are its water equivalent depth of measurement of 0.07 mm, small physical size with submicron dosimetric volume, and the ability to provide real-time readout. A MOSkin detector was calibrated and the reproducibility, linearity, and response over a large dose range to different threshold voltages were determined. Surface dose on solid water phantom was measured using MOSkin detector and compared with Markus ionization chamber and GAFCHROMIC EBT2 film measurements. Dependence in the response of the MOSkin detector on the surface of solid water phantom was also tested for different (i) source to surface distances (SSDs); (ii) field sizes; (iii) surface dose; (iv) radiation incident angles; and (v) wedges. The MOSkin detector showed excellent reproducibility and linearity for dose range of 50 cGy to 300 cGy. The MOSkin detector showed reliable response to different SSDs, field sizes, surface, radiation incident angles, and wedges. The MOSkin detector is suitable for in vivo skin dosimetry.
    Matched MeSH terms: Equipment Failure Analysis
  3. Hashim Y, Sidek O
    J Nanosci Nanotechnol, 2013 Jan;13(1):242-9.
    PMID: 23646723
    This study is the first to demonstrate dimensional optimization of nanowire-complementary metal-oxide-semiconductor inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. Results indicate that optimization depends on both dimensions ratio and digital voltage level (Vdd). Diameter optimization reveals that when Vdd increases, the optimized value of (Dp/Dn) decreases. Channel length optimization results show that when Vdd increases, the optimized value of Ln decreases and that of (Lp/Ln) increases. Dimension ratio optimization reveals that when Vdd increases, the optimized value of Kp/Kn decreases, and silicon nanowire transistor with suitable dimensions (higher Dp and Ln with lower Lp and Dn) can be fabricated.
    Matched MeSH terms: Equipment Failure Analysis
  4. Duray GZ, Ritter P, El-Chami M, Narasimhan C, Omar R, Tolosana JM, et al.
    Heart Rhythm, 2017 05;14(5):702-709.
    PMID: 28192207 DOI: 10.1016/j.hrthm.2017.01.035
    BACKGROUND: Early performance of the Micra transcatheter pacemaker from the global clinical trial reported a 99.2% implant success rate, low and stable pacing capture thresholds, and a low (4.0%) rate of major complications up to 6 months.

    OBJECTIVE: The purpose of this report was to describe the prespecified long-term safety objective of Micra at 12 months and electrical performance through 24 months.

    METHODS: The Micra Transcatheter Pacing Study was a prospective single-arm study designed to assess the safety and efficacy of the Micra VVIR leadless/intracardiac pacemaker. Enrolled patients met class I or II guideline recommendations for de novo ventricular pacing. The long-term safety objective was freedom from a system- or procedure-related major complication at 12 months. A predefined historical control group of 2667 patients with transvenous pacemakers was used to compare major complication rates.

    RESULTS: The long-term safety objective was achieved with a freedom from major complication rate of 96.0% at 12 months (95% confidence interval 94.2%-97.2%; P < .0001 vs performance goal). The risk of major complications for patients with Micra (N = 726) was 48% lower than that for patients with transvenous systems through 12 months postimplant (hazard ratio 0.52; 95% confidence interval 0.35-0.77; P = .001). Across subgroups of age, sex, and comorbidities, Micra reduced the risk of major complications compared to transvenous systems. Electrical performance was excellent through 24 months, with a projected battery longevity of 12.1 years.

    CONCLUSION: Long-term performance of the Micra transcatheter pacemaker remains consistent with previously reported data. Few patients experienced major complications through 12 months of follow-up, and all patient subgroups benefited as compared to transvenous pacemaker historical control group.

    Matched MeSH terms: Equipment Failure Analysis
  5. Mohammad R, Ahmad M, Heng LY
    Sensors (Basel), 2013 Aug 05;13(8):10014-26.
    PMID: 23921830 DOI: 10.3390/s130810014
    Chili hotness is very much dependent on the concentration of capsaicin present in the chili fruit. A new biosensor based on a horseradish peroxidase enzyme-capsaicin reaction mediated by ferrocene has been successfully developed for the amperometric determination of chili hotness. The amperometric biosensor is fabricated based on a single-step immobilization of both ferrocene and horseradish peroxidase in a photocurable hydrogel membrane, poly(2-hydroxyethyl methacrylate). With mediation by ferrocene, the biosensor could measure capsaicin concentrations at a potential 0.22 V (vs. Ag/AgCl), which prevented potential interference from other electroactive species in the sample. Thus a good selectivity towards capsaicin was demonstrated. The linear response range of the biosensor towards capsaicin was from 2.5-99.0 µM with detection limit of 1.94 µM. A good relative standard deviation (RSD) for reproducibility of 6.4%-9.9% was obtained. The capsaicin biosensor demonstrated long-term stability for up to seven months. The performance of the biosensor has been validated using a standard method for the analysis of capsaicin based on HPLC.
    Matched MeSH terms: Equipment Failure Analysis
  6. Reshak AH, Shahimin MM, Shaari S, Johan N
    Prog Biophys Mol Biol, 2013 Nov;113(2):327-32.
    PMID: 24139943 DOI: 10.1016/j.pbiomolbio.2013.10.002
    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
    Matched MeSH terms: Equipment Failure Analysis
  7. Sorooshian S, Kamarozaman AA
    Sao Paulo Med J, 2018;136(5):497-498.
    PMID: 30208126 DOI: 10.1590/1516-3180.2018.0296250718
    Matched MeSH terms: Equipment Failure
  8. Goh YH
    Perit Dial Int, 2008 11 5;28(6):626-31.
    PMID: 18981393
    BACKGROUND: Omental wrap is a common cause of catheter obstruction. Current laparoscopic techniques for correcting obstruction include omentopexy and omentectomy. This study evaluates the efficacy of a new laparoscopic technique for revision of obstructed peritoneal dialysis catheters.

    METHODS: Between November 2005 and November 2006, the technique was applied in 18 patients (6 female, 12 male; median age 50 years, range 16 - 73 years) on continuous ambulatory peritoneal dialysis with catheter malfunction secondary to omental wrap. Pneumoperitoneum was induced under general anesthesia. Three ports were inserted. The catheter was released from the omentum and repositioned in the pelvis. The omentum was then folded onto itself in a cephalad direction using silk sutures. This shortened the omentum. The risk of catheter migration was minimized with a polypropylene sling passed through the abdominal wall and around the catheter, then knotted subcutaneously. The sling allowed catheter removal without a new laparoscopy. The outcomes were prospectively evaluated.

    RESULTS: Median operating time was 90 minutes (range 35 - 160 minutes). Adhesiolysis was performed in 4 patients: 1 patient had port-site leakage of dialysate, which settled with abdominal rest; 1 patient had bleeding during adhesiolysis and laparoscopic hemostasis was successful; 1 patient had recurrent catheter obstruction 2 weeks post-operatively and was converted to hemodialysis; and 1 patient had recurrent malfunction secondary to small bowel wrap after 5.5 months; re-salvage was successful. The success rate of the first salvage procedure was 89%(16/18). The catheters were still functioning after a mean follow-up of 16.5 +/- 6.3 months (range 0.5 - 24 months). The 1-year catheter survival rate was 83.3%.

    CONCLUSIONS: Omental folding is a safe and effective technique for salvaging peritoneal dialysis catheters.

    Matched MeSH terms: Equipment Failure
  9. Crabtree JH, Shrestha BM, Chow KM, Figueiredo AE, Povlsen JV, Wilkie M, et al.
    Perit Dial Int, 2019 04 26;39(5):414-436.
    PMID: 31028108 DOI: 10.3747/pdi.2018.00232
    Matched MeSH terms: Equipment Failure
  10. Chong SS, Aziz AR, Harun SW, Arof H
    Sensors (Basel), 2014;14(9):15836-48.
    PMID: 25166498 DOI: 10.3390/s140915836
    In this study, the construction and test of tapered plastic optical fiber (POF) sensors, based on an intensity modulation approach are described. Tapered fiber sensors with different diameters of 0.65 mm, 0.45 mm, and 0.35 mm, were used to measure various concentrations of Remazol black B (RBB) dye aqueous solutions at room temperature. The concentrations of the RBB solutions were varied from 0 ppm to 70 ppm. In addition, the effect of varying the temperature of the RBB solution was also investigated. In this case, the output of the sensor was measured at four different temperatures of 27 °C, 30 °C, 35 °C, and 40 °C, while its concentration was fixed at 50 ppm and 100 ppm. The experimental results show that the tapered POF with d = 0.45 mm achieves the best performance with a reasonably good sensitivity of 61 × 10(-4) and a linearity of more than 99%. It also maintains a sufficient and stable signal when heat was applied to the solution with a linearity of more than 97%. Since the transmitted intensity is dependent on both the concentration and temperature of the analyte, multiple linear regression analysis was performed to combine the two independent variables into a single equation. The resulting equation was then validated experimentally and the best agreement between the calculated and experimental results was achieved by the sensor with d = 0.45 mm, where the minimum discrepancy is less than 5%. The authors conclude that POF-based sensors are suitable for RBB dye concentration sensing and, with refinement in fabrication, better results could be achieved. Their low fabrication cost, simple configuration, accuracy, and high sensitivity would attract many potential applications in chemical and biological sensing.
    Matched MeSH terms: Equipment Failure Analysis
  11. Halmi MI, Jirangon H, Johari WL, Rachman AR, Shukor MY, Syed MA
    ScientificWorldJournal, 2014;2014:834202.
    PMID: 24977231 DOI: 10.1155/2014/834202
    Luminescence-based assays for toxicants such as Microtox, ToxAlert, and Biotox have been used extensively worldwide. However, the use of these assays in near real time conditions is limited due to nonoptimal assay temperature for the tropical climate. An isolate that exhibits a high luminescence activity in a broad range of temperatures was successfully isolated from the mackerel, Rastrelliger kanagurta. This isolate was tentatively identified as Photobacterium sp. strain MIE, based on partial 16S rDNA molecular phylogeny. Optimum conditions that support high bioluminescence activity occurred between 24 and 30°C, with pH 5.5 to 7.5, 10 to 20 g/L of sodium chloride, 30 to 50 g/L of tryptone, and 4 g/L of glycerol as the carbon source. Assessment of near real time capability of this bacterial system, Xenoassay light to monitor heavy metals from a contaminated river running through the Juru River Basin shows near real time capability with assaying time of less than 30 minutes per samples. Samples returned to the lab were tested with a standard Microtox assay using Vibrio fishceri. Similar results were obtained to Xenoassay light that show temporal variation of copper concentration. Thus, this strain is suitable for near real time river monitoring of toxicants especially in the tropics.
    Matched MeSH terms: Equipment Failure Analysis
  12. Khalil SF, Mohktar MS, Ibrahim F
    Sensors (Basel), 2014;14(6):10895-928.
    PMID: 24949644 DOI: 10.3390/s140610895
    Bioimpedance analysis is a noninvasive, low cost and a commonly used approach for body composition measurements and assessment of clinical condition. There are a variety of methods applied for interpretation of measured bioimpedance data and a wide range of utilizations of bioimpedance in body composition estimation and evaluation of clinical status. This paper reviews the main concepts of bioimpedance measurement techniques including the frequency based, the allocation based, bioimpedance vector analysis and the real time bioimpedance analysis systems. Commonly used prediction equations for body composition assessment and influence of anthropometric measurements, gender, ethnic groups, postures, measurements protocols and electrode artifacts in estimated values are also discussed. In addition, this paper also contributes to the deliberations of bioimpedance analysis assessment of abnormal loss in lean body mass and unbalanced shift in body fluids and to the summary of diagnostic usage in different kinds of conditions such as cardiac, pulmonary, renal, and neural and infection diseases.
    Matched MeSH terms: Equipment Failure Analysis
  13. Yee R, Gadler F, Hussin A, Bin Omar R, Khaykin Y, Verma A, et al.
    Heart Rhythm, 2014 Jul;11(7):1150-5.
    PMID: 24801899 DOI: 10.1016/j.hrthm.2014.04.020
    Left ventricular (LV) lead implantation for cardiac resynchronization therapy (CRT) is associated with lead dislodgement rates ranging from 3% to 10%, and some implant approaches to prevent dislodgement may contribute to suboptimal CRT response. We report our early human experience with an LV lead with a side helix for active fixation to the coronary vein wall.
    Matched MeSH terms: Equipment Failure
  14. Thavanathan J, Huang NM, Thong KL
    Biosens Bioelectron, 2014 May 15;55:91-8.
    PMID: 24368225 DOI: 10.1016/j.bios.2013.11.072
    The unique property of gold nanoparticles (Au NP) to induce colour change and the versatility of graphene oxides (GO) in surface modification makes them ideal in the application of colorimetric biosensor. Thus we developed a label free optical method to detect DNA hybridization through a visually observed colour change. The Au NP is conjugated to a DNA probe and is allowed to hybridize with the DNA target to the GO thus causing a change in colour from pinkish-red to purplish blue. Spectrophometry analysis gave a wavelength shift of 22 nm with 1 µM of DNA target. Sensitivity testing using serially diluted DNA conjugated GO showed that the optimum detection was at 63 nM of DNA target with the limit at 8 nM. This proves the possibility for the detection of DNA hybridization through the use of dual nanoparticle system by visual observation.
    Matched MeSH terms: Equipment Failure Analysis
  15. Ahmad H, Thambiratnam K, Zulkifli AZ, Lawrence A, Jasim AA, Kunasekaran W, et al.
    Sensors (Basel), 2013 Sep 30;13(10):13276-88.
    PMID: 24084118 DOI: 10.3390/s131013276
    An efficient and low cost optical method for directly measuring the concentration of homogenous biological solutes is proposed and demonstrated. The proposed system operates by Fresnel reflection, with a flat-cleaved single-mode fiber serving as the sensor probe. A laser provides a 12.9 dBm sensor signal at 1,550 nm, while a computer-controlled optical power meter measures the power of the signal returned by the probe. Three different mesenchymal stem cell (MSC) lines were obtained, sub-cultured and trypsinized daily over 9 days. Counts were measured using a haemocytometer and the conditioned media (CM) was collected daily and stored at -80 °C. MSCs release excretory biomolecules proportional to their growth rate into the CM, which changes the refractive index of the latter. The sensor is capable of detecting changes in the number of stem cells via correlation to the change in the refractive index of the CM, with the measured power loss decreasing approximately 0.4 dB in the CM sample per average 1,000 cells in the MSC subculture. The proposed system is highly cost-effective, simple to deploy, operate, and maintain, is non-destructive, and allows reliable real-time measurement of various stem cell proliferation parameters.
    Matched MeSH terms: Equipment Failure Analysis
  16. Chan YJ, Chong MF, Law CL
    Bioresour Technol, 2012 Dec;125:145-57.
    PMID: 23026327 DOI: 10.1016/j.biortech.2012.08.118
    Thermophilic treatment of palm oil mill effluent (POME) was studied in a novel integrated anaerobic-aerobic bioreactor (IAAB). The IAAB was subjected to a program of steady-state operation over a range of organic loading rate (OLR)s, up to 30 g COD/L day in order to evaluate its treatment capacity. The thermophilic IAAB achieved high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of more than 99% for OLR up to 18.5 g COD/L day. High methane yield of 0.32 LCH(4) (STP)/g COD(removed) with compliance of the final treated effluent to the discharge limit were achieved. This is higher than that of the mesophilic system due to the higher maximum specific growth rate (μ(max)) of the thermophilic microorganisms. Besides, coupling the model of Grau second order model (anaerobic system) with the model of Monod (aerobic system) will completely define the IAAB system.
    Matched MeSH terms: Equipment Failure Analysis
  17. Rahman HA, Che Ani AI, Harun SW, Yasin M, Apsari R, Ahmad H
    J Biomed Opt, 2012 Jul;17(7):071308.
    PMID: 22894469 DOI: 10.1117/1.JBO.17.7.071308
    The purpose of this study is to investigate the potential of intensity modulated fiber optic displacement sensor scanning system for the imaging of dental cavity. Here, we discuss our preliminary results in the imaging of cavities on various teeth surfaces, as well as measurement of the diameter of the cavities which are represented by drilled holes on the teeth surfaces. Based on the analysis of displacement measurement, the sensitivities and linear range for the molar, canine, hybrid composite resin, and acrylic surfaces are obtained at 0.09667 mV/mm and 0.45 mm; 0.775 mV/mm and 0.4 mm; 0.5109 mV/mm and 0.5 mm; and 0.25 mV/mm and 0.5 mm, respectively, with a good linearity of more than 99%. The results also show a clear distinction between the cavity and surrounding tooth region. The stability, simplicity of design, and low cost of fabrication make it suitable for restorative dentistry.
    Matched MeSH terms: Equipment Failure Analysis
  18. Tee HC, Lim PE, Seng CE, Nawi MA
    Bioresour Technol, 2012 Jan;104:235-42.
    PMID: 22130081 DOI: 10.1016/j.biortech.2011.11.032
    The objectives of this study are to compare the performance of newly developed baffled and conventional horizontal subsurface-flow (HSF) constructed wetlands in the removal of nitrogen at the hydraulic retention times (HRT) of 2, 3 and 5 days and to evaluate the potential of rice husk as wetland media for wastewater treatment. The results show that the planted baffled unit achieved 74%, 84% and 99% ammonia nitrogen (NH(4)(+)-N) removal versus 55%, 70% and 96% for the conventional unit at HRT of 2, 3 and 5 days, respectively. The better performance of the baffled unit was explained by the longer pathway due to the up-flow and down-flow conditions sequentially thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones. Near complete total oxidized nitrogen was observed due to the use of rice husk as wetland media which provided the COD as the electron donor in the denitrification process.
    Matched MeSH terms: Equipment Failure Analysis
  19. Sulaiman AR, Simbak N, Wan Ismail WF, Wan Z, Halim AS
    J Orthop Surg (Hong Kong), 2011 Aug;19(2):250-3.
    PMID: 21857057
    We report 2 patients with congenital pseudoarthrosis of the tibia who underwent intramedullary Rush rod transfixation through the ankle joint following refracture and nonunion of vascularised fibular grafting 6 and 8 months earlier. After 9 and 5 years, both Rush rods were broken at the level of the ankle joints, while the reconstructed area was solidly united. The growth of the distal tibia increased the distance of the tips of the broken rod and hence the ankle joint motion. The broken tips may damage the articular cartilage and result in valgus deformity of the ankle and limb length discrepancy.
    Matched MeSH terms: Equipment Failure
  20. Khan A, Ab Ghani S
    Biosens Bioelectron, 2012 Jan 15;31(1):433-8.
    PMID: 22154168 DOI: 10.1016/j.bios.2011.11.007
    The electrochemical biosensors based on poly(o-phenylenediamine) (PoPD) and acetylcholinesterase (AChE) and choline oxidase (ChO) enzymes were fabricated on carbon fibre (CF) substrate. The electropolymerized PoPD was used to reduce the interfering substances. The electrode assembly was completed by depositing functionalized carbon nano tubes (FCNTs) and Nafion (Naf). Amperometric detection of acetylcholine (ACh) and choline (Ch) were realized at an applied potential of +750 mV vs Ag/AgCl (saturated KCl). At pH 7.4, the final assembly, Naf-FCNTs/AChE-ChO((10:1))/PoPD/CF(Elip), was observed to have high sensitivity towards Ch (6.3±0.3 μA mM(-1)) and ACh (5.8±0.3 μA mM(-1)), linear range for Ch (K(M)=0.52±0.03 mM) and ACh (K(M)=0.59±0.07 mM), and for Ch the highest ascorbic acid blocking capacity (97.2±2 1mM AA). It had a response time of <5s and with 0.045 μM limit of detection. Studies on different ratio (ACh/Ch) revealed that 10:1, gave best overall response.
    Matched MeSH terms: Equipment Failure Analysis
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