Displaying publications 1 - 20 of 42 in total

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  1. Al-Faqheri W, Ibrahim F, Thio TH, Moebius J, Joseph K, Arof H, et al.
    PLoS One, 2013;8(3):e58523.
    PMID: 23505528 DOI: 10.1371/journal.pone.0058523
    This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control.
    Matched MeSH terms: Centrifugation*
  2. Thio TH, Soroori S, Ibrahim F, Al-Faqheri W, Soin N, Kulinsky L, et al.
    Med Biol Eng Comput, 2013 May;51(5):525-35.
    PMID: 23292292 DOI: 10.1007/s11517-012-1020-7
    This paper presents a theoretical development and critical analysis of the burst frequency equations for capillary valves on a microfluidic compact disc (CD) platform. This analysis includes background on passive capillary valves and the governing models/equations that have been developed to date. The implicit assumptions and limitations of these models are discussed. The fluid meniscus dynamics before bursting is broken up into a multi-stage model and a more accurate version of the burst frequency equation for the capillary valves is proposed. The modified equations are used to evaluate the effects of various CD design parameters such as the hydraulic diameter, the height to width aspect ratio, and the opening wedge angle of the channel on the burst pressure.
    Matched MeSH terms: Centrifugation/instrumentation
  3. Al-Faqheri W, Ibrahim F, Thio TH, Bahari N, Arof H, Rothan HA, et al.
    Sensors (Basel), 2015 Feb 25;15(3):4658-76.
    PMID: 25723143 DOI: 10.3390/s150304658
    In this paper, we propose an easy-to-implement passive liquid valve (PLV) for the microfluidic compact-disc (CD). This valve can be implemented by introducing venting chambers to control the air flow of the source and destination chambers. The PLV mechanism is based on equalizing the main forces acting on the microfluidic CD (i.e., the centrifugal and capillary forces) to control the burst frequency of the source chamber liquid. For a better understanding of the physics behind the proposed PLV, an analytical model is described. Moreover, three parameters that control the effectiveness of the proposed valve, i.e., the liquid height, liquid density, and venting chamber position with respect to the CD center, are tested experimentally. To demonstrate the ability of the proposed PLV valve, microfluidic liquid switching and liquid metering are performed. In addition, a Bradford assay is performed to measure the protein concentration and evaluated in comparison to the benchtop procedure. The result shows that the proposed valve can be implemented in any microfluidic process that requires simplicity and accuracy. Moreover, the developed valve increases the flexibility of the centrifugal CD platform for passive control of the liquid flow without the need for an external force or trigger.
    Matched MeSH terms: Centrifugation*
  4. Park S, Jalaludin I, Hwang H, Ko M, Adelipour M, Hwan M, et al.
    PMID: 37480686 DOI: 10.1016/j.jchromb.2023.123828
    In recent years, extracellular vesicles (EVs) have gained attention for their potential as biomarkers for the early diagnosis and treatment of various diseases. Traditionally, EV isolation has relied exclusively on ultracentrifugation. However, alternative enrichment methods such as size-exclusion chromatography (SEC) and polyethylene glycol-based precipitation have been introduced. This study utilized SEC as a characterization tool to assess the efficiency of EV isolation. Urinary EVs isolated from human urine using centrifugation (40,000 × g) were analyzed using an SEC column with a pore size of 1000 Å, an inner diameter of 7.8 mm, and a length of 300 mm. The EVs were detected sequentially using UV (280 nm) and fluorescence (λex/em = 550 nm/565 nm); the EVs were observed at approximately 6 min, while the proteins were observed at approximately 12 min. The repeated centrifugation enrichment steps resulted in an increase in EV peaks and a decrease in protein peaks. SEC analysis of the enriched EV samples confirmed that a four-cycle repetition of centrifugation is necessary for successful EV enrichment and removal of non-EV proteins from 40 mL of human urine.
    Matched MeSH terms: Centrifugation
  5. Lee IL, Tan TC, Govind SK
    Exp Parasitol, 2019 Mar;198:105-110.
    PMID: 30695704 DOI: 10.1016/j.exppara.2019.01.007
    This study was aimed at establishing a protocol for water sample processing for the detection of Blastocystis sp. using distilled water spiked with Blastocystis sp. cysts. The study established a protocol involving eight technical aspects, namely, storage temperature, storage duration, minimum water sample volume, optimum relative centrifugal force, centrifugation duration, minimum number of cyst for inoculation in Jones' medium and turn-around-time for the detection of vacuolar forms of Blastocystis sp. Results showed a minimum of 1.0 L water sample should be collected and processed on the same day. Otherwise, it should be stored at 4 °C and processed within 3 days. Water sample should be centrifuged at 1400×g for 10 min. For the isolation of Blastocystis sp. cysts, parasite pellet could be layered on top of Ficoll-Paque™ PLUS, centrifuged at 1400×g for 20 min and washed twice using 0.9% saline with centrifugation at 1400×g for 10 min. A minimum of 1 × 105 cysts could then be inoculated in Jones' medium supplement with 10% horse serum, incubated at 37 °C and examined for any presence of vacuolar forms of Blastocystis sp. after 3 days of inoculation. A protocol for water sample processing for the detection of Blastocystis sp. has successfully been established. The protocol was validated using 106 various water samples. This protocol will be very useful in determining the extent of Blastocystis sp. contamination in water sources in order to identify the seriousness of contamination.
    Matched MeSH terms: Centrifugation
  6. Hamid MSA
    Wounds, 2018 Jul;30(7):186-190.
    PMID: 30059343
    INTRODUCTION: Despite limited clinical evidence, platelet-rich plasma (PRP) is currently used for the treatment of various soft tissue injuries, but optimal use of PRP has yet to be determined. In many instances, PRP is prepared using commercial devices that lack standardized preparation techniques and consistent quality of the PRP produced.

    OBJECTIVE: The aim of this study is to explore a simple, easy, economical method of PRP preparation that is practical for clinical use.

    MATERIALS AND METHODS: This cross-sectional study was conducted at the Sports Medicine Clinic at the University of Malaya Medical Centre, Malaysia. Participants were healthy postgraduate students and staff at the Sports Medicine Department. The PRP was prepared using a single centrifugation technique. Leukocyte and platelet levels were compared with that of a whole blood baseline and a commercial preparation kit.

    RESULTS: The PRP produced using this technique contained significantly higher mean platelet (1725.0 vs. 273.9 x 109/L) and leukocyte (33.6 vs. 7.7 x 109/L) levels compared with whole blood. There was no significant difference in the mean platelet and leukocyte levels between the PRP produced in this study and by a commercial PRP system.

    CONCLUSIONS: A single-centrifugation protocol using readily available materials in a typical clinical setting could produce PRP of comparable quality to those of a commercial PRP production system.

    Matched MeSH terms: Centrifugation/economics; Centrifugation/methods*
  7. Jahadi M, Khosravi-Darani K, Ehsani MR, Mozafari MR, Saboury AA, Pourhosseini PS
    J Food Sci Technol, 2015 Apr;52(4):2063-72.
    PMID: 25829586 DOI: 10.1007/s13197-013-1243-0
    The main objective of this study was to use heating method (HM) to prepare liposome without employing any chemical solvent or detergent. Plackett-Burman design (PBD) was applied for the screening of significant process variables including the lecithin proportion, the cholesterol/lecithin ratio, the pH of solution for liposome preparation, the enzyme/lecithin ratio, the stirring time, the process temperature, the speed of stirrer, the ratio of stirrer to the tank diameter, the application of homogenization, the method of adding enzyme and centrifugation conditions on the encapsulation efficiency (EE %) of liposome and the activity of liposomal Flavourzyme (LAPU(-1)) (P 
    Matched MeSH terms: Centrifugation
  8. Nur Syahira Mohammad, Zaidah Zainal Ariffin
    Science Letters, 2020;14(2):15-23.
    MyJurnal
    Fungi is known to produce a wide range of biologically active metabolites and enzymes. Enzymes produced by fungi are utilized in food and pharmaceutical industries because of their rich enzymatic profile. Filamentous fungi are particularly interesting due to their high production of extracellular enzymes which has a large industrial potential. The aim of this study is to isolate potential soil fungi species that are able to produce functional enzymes for industries. Five Aspergillus species were successfully isolated from antibiotic overexposed soil (GPS coordinate of N3.093219 E101.40269) by standard microbiological method. The isolated fungi were identified via morphological observations and molecular tools; polymerase chain reactions, ITS 1 (5’- TCC GTA GGT GAA CCT GCG G3’) forward primer and ITS 4 (5’-TCC TCC GCT TAT TGA TAT GC-3’) reverse primer. The isolated fungi were identified as Aspergillus sydowii strain SCAU066, Aspergillus tamarii isolate TN-7, Aspergillus candidus strain KUFA 0062, Aspergillus versicolor isolate BAB-6580, and Aspergillus protuberus strain KAS 6024. Supernatant obtained via submerged fermentation of the isolated fungi in potato dextrose broth (PDB) and extracted via centrifugation was loaded onto specific media to screen for the production of xylanolytic, cellulolytic and amylolytic enzymes. The present findings indicate that Aspergillus sydowii strain SCAU066 and Aspergillus versicolor isolate BAB-6580 have great potential as an alternative source of xylanolytic, cellulolytic and amylolytic enzymes.
    Matched MeSH terms: Centrifugation
  9. Arina Nasruddin, Azura Amid, Muhd Ezza Faiez Othman
    MyJurnal
    Green chemical method was applied to synthesize nanoparticles using recombinant
    bromelain. Among the numerous applications of recombinant bromelain, there is still no research
    on nanoparticles synthesis which encourages its utilization in this study. Four chemicals which are
    copper (II) chloride dihydrate (CuCl2.2H2O), cerium nitrate hexahydrate (Ce(NO3)3.6H2O), sodium
    selenite (Na2SeO3), and iron (III) chloride hexahydrate (FeCl3.6H2O) were selected to be screened
    for the suitability in nanoparticles biosynthesis by recombinant bromelain. The nanoparticles
    formed were characterized by using UV-visible absorption spectra. The biosynthesis process then
    was optimized by varying the centrifugation speed, temperature, and time to get the maximum
    absorption and weight of nanoparticles through central composite design (CCD) tool. Only
    CuCl2.2H2O showed a positive result for the screening process which was represented by the
    formation of colloidal solution and a maximum absorption at 580 nm. Thus, optimization was
    carried out for this chemical. Based on the optimization model, maximum absorption and weight
    were predicted at 67.5°C, 2 hrs, and 9,600 rpm. These optimal conditions were validated by
    repeating the biosynthesis process. The absorption and weight of the nanoparticles depended on the
    reaction of the chemical with recombinant bromelain. 3D plots showed that the optimal condition
    for high responses mostly depends on temperature and time.
    Matched MeSH terms: Centrifugation
  10. Kavitha, G., Sangeetha, V.N., Shani, S., Murali, M.R., Raja, E.A., Rukmanikanthan, S., et al.
    JUMMEC, 2011;14(2):1-6.
    MyJurnal
    INTRODUCTION: Despite the various methods described in producing platelet-rich plasma (PRP), it is well established that this biological product in its many preparations have been proven to enhance wound healing. However, very little have been known about the efficacy of these methods hence there is a lack of evidence in the superiority of one method over another. Thus, a study was conducted to compare these different protocols to determine which produces the highest concentration of platelets.
    METHODS: Peripheral blood was obtained from 24 healthy volunteers. Four different protocols using similar 2 step centrifugation methods of preparing PRP were applied to an equal number of samples in this study. Platelet counts were performed on whole blood (without processing), PRP preparations and platelet-poor plasma (PPP).
    RESULTS: All protocols produced higher amounts of platelet concentrates in PRP preparations than plasma. However, centrifugation at 150g for 10 minutes followed by another at 450g at 10 minutes produces significantly higher amount of platelets concentration (p<0.05)
    CONCLUSION: Optimizing the protocols to produce PRP appears to be important in obtaining a maximal yield of platelet concentrate. Here the protocol described has shown to provide significant concentration yield over all others.
    Keywords: platelet-rich-plasma, growth factors, centrifugal forces
    Matched MeSH terms: Centrifugation
  11. Azlin, I., Hafiza, A., Azma, R.Z., Aidifitrina, R.K., Hamidah, N.H.
    Medicine & Health, 2011;6(1):68-72.
    MyJurnal
    Centrifugation of blood samples to produce platelet-poor plasma is one of the important steps for coagulation testing. Reduction of the time required for specimen processing without affecting quality of results should be ideal for tests which require immediate results. Centrifugation of platelet-poor plasma (3580 rpm) for 15 minutes performed for routine coagulation tests would prolong the turn-around time for an urgent test (30 minutes). This study was done to determine the effect of reducing centrifugation time for routine coagulation tests in order to meet the turn-around time (TAT) for urgent tests. Seventy-nine blood samples sent for routine coagulation tests, were assayed for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level and platelet counts, using two different centrifugation speed for plasma preparation: centrifugation at 3580 rpm for 15 minutes and rapid centrifugation at 4000 rpm for five minutes. Paired sample t-test showed that there was a significant
    difference in the platelet count between the two groups (p=0.001). However, there was no significant difference in the normal APTT (p=0.16), abnormal APTT (p=0.80), abnormal PT (p=0.43) and the results of fibrinogen levels (p=0.36). In conclusion, rapid centrifugation at 4000 rpm for five minutes does not modify results of routine coagulation tests (PT, APTT and fibrinogen). It would be beneficial in providing rapid results for urgent coagulation tests.
    Matched MeSH terms: Centrifugation
  12. Chai CK, Md. Soot Ahmad, Wan Manshol W. Zin
    Electron beam vulcanization of natural rubber latex has been developed as an alternative to the conventional sulphur vulcanization method. This study aimed at determining the effect of electron beam dose, beam current and centrifugation to the tensile properties of field natural rubber latex. Irradiation dose and beam current ranged from 50 to 300 kGy and 1 to 15 mA respectively. The determination of tensile properties were done on cast film prepared from irradiated field latex before and after centrifugation. It was found that tensile properties increased with radiation dose but decreased with beam current. Rubber films made from centrifuged irradiated field latex were softer and showed higher tensile strength.
    Matched MeSH terms: Centrifugation
  13. Aeinehvand MM, Ibrahim F, Harun SW, Al-Faqheri W, Thio TH, Kazemzadeh A, et al.
    Lab Chip, 2014 Mar 07;14(5):988-97.
    PMID: 24441792 DOI: 10.1039/c3lc51116b
    Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon.
    Matched MeSH terms: Centrifugation
  14. Mahmoodian R, Yahya R, Dabbagh A, Hamdi M, Hassan MA
    PLoS One, 2015;10(12):e0144632.
    PMID: 26641651 DOI: 10.1371/journal.pone.0144632
    A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite.
    Matched MeSH terms: Centrifugation
  15. Loo CY, Sudesh K
    Int J Biol Macromol, 2007 Apr 10;40(5):466-71.
    PMID: 17207850
    The ability of Delftia acidovorans to incorporate a broad range of 3-hydroxyvalerate (3HV) monomers into polyhydroxyalkanoate (PHA) copolymers was evaluated in this study. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] containing 0-90 mol% of 3HV was obtained when a mixture of sodium 3-hydroxybutyrate and sodium valerate was used as the carbon sources. Transmission electron microscopy analysis revealed an interesting aspect of the P(3HB-co-3HV) granules containing high molar ratios of 3HV whereby, the copolymer granules were generally larger than those of poly(3-hydroxybutyrate) [P(3HB)] granules, despite having almost the same cellular PHA contents. The large number of P(3HB-co-3HV) granules occupying almost the entire cell volume did not correspond to a higher amount of polymer by weight. This indicated that the granules of P(3HB-co-3HV) contain polymer chains that are loosely packed and therefore have lower density than P(3HB) granules. It was also interesting to note that a decrease in the length of the side chain from 3HV to 4-hydroxybutyrate (4HB) corresponded to an increase in the density of the respective PHA granules. The presence of longer side chain monomers (3HV) in the PHA structure seem to exhibit steric effects that prevent the polymer chains in the granules from being closely packed. The results reported here have important implications on the maximum ability of bacterial cells to accumulate PHA containing monomers with longer side chain length.
    Matched MeSH terms: Centrifugation, Density Gradient
  16. Ling TC, Loong CK, Tan WS, Tey BT, Abdullah WM, Ariff A
    J Microbiol, 2004 Sep;42(3):228-32.
    PMID: 15459653
    In this paper, we investigated the development of a simplified and rapid primary capture step for the recovery of M13 bacteriophage from particulate-containing feedstock. M13 bacteriophage, carrying an insert, was propagated and subsequently purified by the application of both conventional multiple steps and expanded bed anion exchange chromatography. In the conventional method, precipitation was conducted with PEG/NaCl, and centrifugation was also performed. In the single step expanded bed anion exchange adsorption, UpFront FastLine 20 (20 mm i.d.) from UpFront Chromatography was used as the contactor, while 54 ml (Ho = 15 cm) of STREAMLINE DEAE (rho = 1.2 g/cm3) from Amersham Pharmacia Biotechnology was used as the anion exchanger. The performance of the two methods were evaluated, analysed, and compared. It was demonstrated that the purification of the M13 bacteriophage, using expanded bed anion exchange adsorption, yielded the higher recovery percentage, at 82.86%. The conventional multiple step method yielded the lower recovery percentage, 36.07%. The generic application of this integrated technique has also been assessed.
    Matched MeSH terms: Centrifugation
  17. de Barjac H, Sebald M, Charles JF, Cheong WH, Lee HL
    C. R. Acad. Sci. III, Sci. Vie, 1990;310(9):383-7.
    PMID: 1972899
    A strain of Clostridium bifermentans individualized as serovar malaysia (C.b.m.) according to its specific H antigen is toxic to mosquito and blackfly larvae when given orally. The toxicity occurs in sporulated cells which contain, in addition to spores, proteinic parasporal inclusion bodies and feather-like appendages; the amino acid content of the inclusion bodies is similar to that of Bacillus thuringiensis serovar israelensis (B.t.i.) and B. sphaericus crystals. The toxicity to Anopheles stephensi is as high as that of B.t.i. and the best strains of B. sphaericus. Culex pipiens is somewhat less susceptible, and Aedes aegypti much less. Pure parasporal inclusion bodies, isolated by ultracentrifugation on sucrose gradients, are highly toxic to mosquito larvae. The larvicidal power is destroyed by heating at 80 degrees C or by treatment with 50 mM NaOH. It is preserved by freeze-drying. The innocuity to mice of the sporulated cells is shown by different routes of administration: force-feeding, percutaneous, subcutaneous, intraperitoneal or intravenous injections. The potential for the biological control of mosquito and blackfly larvae is suggested.
    Matched MeSH terms: Centrifugation, Density Gradient
  18. Shan TO, Mee LN, Marinah Mohd Ariffin, Saw HL
    Sains Malaysiana, 2017;46:615-621.
    Bisphenol A is an endocrine disruptor with widespread applications, especially in the production of polycarbonate and epoxy resins. Dispersive liquid-liquid microextraction based on solidification of floating organic technique has been developed for the extraction of bisphenol A from water and soft drink. The 1-undecanol has been applied as the extraction solvent because of its low density and melting point and high affinity to the analyte. The technique offered rapid and simple analysis as the 1-undecanol was homogeneously dispersed in the sample solution to speed the extraction and the collection of extraction solvent was simplified by centrifugation, cooling and melting steps.
    Matched MeSH terms: Centrifugation
  19. Emami Moghaddam SA, Harun R, Mokhtar MN, Zakaria R
    Biomed Res Int, 2018;2018:6563196.
    PMID: 30643814 DOI: 10.1155/2018/6563196
    The interest in utilizing algae for wastewater treatment has been increased due to many advantages. Algae-wastewater treatment system offers a cost-efficient and environmentally friendly alternative to conventional treatment processes such as electrocoagulation and flocculation. In this biosystem, algae can assimilate nutrients in the wastewater for their growth and simultaneously capture the carbon dioxide from the atmosphere during photosynthesis resulting in a decrease in the greenhouse gaseousness. Furthermore, the algal biomass obtained from the treatment process could be further converted to produce high value-added products. However, the recovery of free suspended algae from the treated effluent is one of the most important challenges during the treatment process as the current methods such as centrifugation and filtration are faced with the high cost. Immobilization of algae is a suitable approach to overcome the harvesting issue. However, there are some drawbacks with the common immobilization carriers such as alginate and polyacrylamide related to low stability and toxicity, respectively. Hence, it is necessary to apply a new carrier without the mentioned problems. One of the carriers that can be a suitable candidate for the immobilization is zeolite. To date, various types of zeolite have been used for the immobilization of cells of bacteria and yeast. If there is any possibility to apply them for the immobilization of algae, it needs to be considered in further studies. This article reviews cell immobilization technique, biomass immobilization onto zeolites, and algal immobilization with their applications. Furthermore, the potential application of zeolite as an ideal carrier for algal immobilization has been discussed.
    Matched MeSH terms: Centrifugation
  20. Amiza, M.A., Ow, Y.W., Faazaz, A.L.
    MyJurnal
    The physicochemical properties of silver catfish frame hydrolysate powder at three different degree of hydrolysis, DH43%, DH 55% and DH 68% were studied. The hydrolysates powder were obtained by hydrolysis using Alcalase®, centrifugation and spray drying of the supernatant. The study found that preparation of these hydrolysates affected the protein, ash and fat content as well as amino acid composition. As for essential amino acids, their values were generally considered as adequate as compared to the suggested essential amino acids profile of FAO/WHO. The results showed that SFHs were rich in lysine and glutamate. Hydrolysate at DH 68% exhibited better peptide solubility and water holding capacity. As degree of hydrolysis increased, emulsifying capacity and foaming capacity of the hydrolysate decreased. It was also found that the lightness in hydrolysate powder decreased with increase in degree of hydrolysis. This study shows that silver catfish frame hydrolysate has good solubility, good foaming properties and light colour profile, thus having high potential as food ingredient.
    Matched MeSH terms: Centrifugation
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