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Fulltext Effects of using silica fume and polycarboxylate-type superplasticizer on physical properties of cementitious grout mixtures for semiflexible pavement surfacing

Koting S, Karim MR, Mahmud H, Mashaan NS, Ibrahim MR, Katman H, et al.

ScientificWorldJournal, 2014;2014:596364.
PMID: 24526911 DOI: 10.1155/2014/596364

Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is subsequently grouted with appropriate cementitious materials. This study aims to investigate the compressive strength, flexural strength, and workability performance of cementitious grout. The grout mixtures are designed to achieve high strength and maintain flow properties in order to allow the cement slurries to infiltrate easily through unfilled compacted skeletons. A paired-sample t-test was carried out to find out whether water/cement ratio, SP percentages, and use of silica fume influence the cementitious grout performance. The findings showed that the replacement of 5% silica fume with an adequate amount of superplasticizer and water/cement ratio was beneficial in improving the properties of the cementitious grout.

Matched MeSH terms: Polycarboxylate Cement/chemistry*
Fulltext Warpage Optimisation Using Recycled Polycar-bonates (PC) on Front Panel Housing

Tamizi NAMA, Rahim SZA, Abdellah AE, Abdullah MMAB, Nabiałek M, Wysłocki JJ, et al.

Materials (Basel), 2021 Mar 15;14(6).
PMID: 33804036 DOI: 10.3390/ma14061416

Many studies have been done using recycled waste materials to minimise environmental problems. It is a great opportunity to explore mechanical recycling and the use of recycled and virgin blend as a material to produce new products with minimum defects. In this study, appropriate processing parameters were considered to mould the front panel housing part using R0% (virgin), R30% (30% virgin: 70% recycled), R40% (40% virgin: 60% recycled) and R50% (50% virgin: 50% recycled) of Polycarbonate (PC). The manufacturing ability and quality during preliminary stage can be predicted through simulation analysis using Autodesk Moldflow Insight 2012 software. The recommended processing parameters and values of warpage in x and y directions can also be obtained using this software. No value of warpage was obtained from simulation studies for x direction on the front panel housing. Therefore, this study only focused on reducing the warpage in the y direction. Response Surface Methodology (RSM) and Genetic Algorithm (GA) optimisation methods were used to find the optimal processing parameters. As the results, the optimal ratio of recycled PC material was found to be R30%, followed by R40% and R50% materials using RSM and GA methods as compared to the average value of warpage on the moulded part using R0%. The most influential processing parameter that contributed to warpage defect was packing pressure for all materials used in this study.

Matched MeSH terms: Polycarboxylate Cement
The effect of temperature change on the working and setting time of two luting cements

Abdullah H, Pearson GJ

Asian J Aesthet Dent, 1993 Jul;1(2):91-4.
PMID: 7921802

The effect of temperature change on the working and setting time of a glass ionomer luting cement and a resin luting cement was measured using the oscillating rheometer. The time taken for each cement to set was calculated from the chart recordings. It was observed that as the temperature increased, the working and setting time of both materials decreased. However, the reduction was much more marked for the dual curing resin cement.

Matched MeSH terms: Polycarboxylate Cement/chemistry*
Leaching of bisphenol A from new and old babies' bottles, and new babies' feeding teats

Tan BL, Mustafa AM

Asia Pac J Public Health, 2003;15(2):118-23.
PMID: 15038686

Bisphenol A is the monomer used in the manufacture of polycarbonate. Bisphenol A is also known to mimic the female hormone estrogen. In this study, the possibility of the leaching of bisphenol A from polycarbonate babies' bottles and feeding teats was investigated. Bisphenol A was extracted from water samples exposed to the bottles and teats using liquid-liquid extraction. Bisphenol A was analysed by gas chromatograph-mass spectrometer with quadrapole detector in selected ion monitoring mode. Mean leaching of bisphenol A from 100 used babies' bottles when filled with water at 25 degrees C and 80 degrees C were 0.71 +/- 1.65 ng/cm2 (mean +/- standard deviation) and 3.37 +/- 5.68 ng/cm2 respectively. Mean leaching of bisphenol A from 30 new babies' bottles when filled with water at 25 degrees C and 80 degrees C were 0.03 +/- 0.02 ng/cm2 and 0.18 degrees 0.30 ng/cm2 respectively. Bisphenol A was observed to have leached from babies' feeding teats into 37 degrees C water ranged from non-detectable to 22.86 ng/g. The technique employed in this study is fast, reliable and economical.

Matched MeSH terms: Polycarboxylate Cement/chemistry*
Rapid extraction of bisphenol a by dispersive liquid-liquid microextraction based on solidification of floating organic

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: Polycarboxylate Cement
Effect of gamma irradiation on the physical stability of dppc liposomes

Liyana Mohd Ali Napia, Faizal Mohamed, Hur Munawar Kabir Mohd, Intan Syakeela Ahmad Bastamam, Shamellia Sharin, Norsyahidah Mohd Hidzir, et al.

Sains Malaysiana, 2018;47:1235-1240.

Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
produce liposomes with higher stability.

Matched MeSH terms: Polycarboxylate Cement
Synthesis of vegetable-oil based polymer by terpolymerization of epoxidized soybean oil, propylene oxide and carbon dioxide

Shaarani FW, Bou JJ

Sci Total Environ, 2017 Nov 15;598:931-936.
PMID: 28458211 DOI: 10.1016/j.scitotenv.2017.04.184

Although carbon dioxide (CO2) is well known as one of the major green-house gases, it is also an economical C1 resource. Thus, CO2has been regarded as an appealing starting material for the synthesis of polymers, like polycarbonates by the reaction with epoxides. Herein the reaction between natural epoxidized soybean oil (ESO), propylene oxide (PO) and CO2under high pressure (4.0MPa) with the presence of Co-Zn double metal cyanide (Co-Zn DMC) catalyst was studied. Temperature and reaction time were varied accordingly and the products obtained were characterized by FTIR, GPC and1H NMR. The results obtained indicate the formation of polycarbonates in the samples collected with yields vary from 60 to 85%. The number average molecular weight (Mn) of the resultant polymer prepared at reaction temperature of 80°C and reaction time of 6h can reach up to 6498g/mol.

Matched MeSH terms: Polycarboxylate Cement
Generation, characterization and application of atmospheric pressure plasma jet

Shrestha R, Subedi DP, Gurung JP, Wong CS

Sains Malaysiana, 2016;45:1689-1696.

The development of a non-thermal plasma jet with a capillary configuration working at atmospheric pressure is reported
in this paper. The plasma jet is powered by a power source with frequency of several kilohertz. The working gas is
argon. The plasma obtained has been characterized by optical emission spectroscopic measurements and electrical
measurements of the discharge using voltage and current probes. The electron temperature has been estimated by using
the modified Boltzmann plot method utilizing the Ar 4p-4s transition. The electron temperatures at various positions
along the plasma jet length have been obtained and it is found that the electron temperature decreases at position further
from orifice. The electron density has been estimated from current and voltage measurements using the power balance
method. The effects of gas flow rate, applied voltage and frequency on the characteristics of the plasma jet have also been
investigated. The applications of the atmospheric pressure plasma jet (APPJ) developed to modify the surface properties
of Polyethyleneterephthalate (PET) and polycarbonate (PC) have been tested. Our results showed that the atmospheric
pressure non-thermal plasma jet can be effectively used to enhance the surface wettability and surface energy of the
PET and PC. The plasma jet has also been tested for inactivation of prokaryotic cells (Escherichia coli, Staphylococcus
aureus). In the case of E. coli, better than 4 log10 reduction can be achieved. The effect of plasma jet on the pH of cell
culture medium has suggested that the plasma species, particularly the electrons, are solely responsible for the effect
of inactivation of living cells.

Matched MeSH terms: Polycarboxylate Cement
Fulltext Detection of microplastics in human colectomy specimens

Ibrahim YS, Tuan Anuar S, Azmi AA, Wan Mohd Khalik WMA, Lehata S, Hamzah SR, et al.

JGH Open, 2021 Jan;5(1):116-121.
PMID: 33490620 DOI: 10.1002/jgh3.12457

Background and Aim: While dietary exposure to microplastics is increasingly recognized, it is unknown if ingested plastics remain within the digestive tract. We aimed to examine human colectomy specimens for microplastics and to report the characteristics as well as polymer composition of the particles.
Methods: Colectomy samples were obtained from 11 adults (mean age 45.7, six males) who were residents of Northeastern Peninsular Malaysia. Microplastics were identified following chemical digestion of specimens and subsequent filtration. The samples were then examined for characteristics (abundance, length, shape, and color) and composition of three common polymer types using stereo- and Fourier Transform InfraRed (FTIR) microscopes.
Results: Microplastics were detected in all 11 specimens with an average of 331 particles/individual specimen or 28.1 ± 15.4 particles/g tissue. Filaments or fibers accounted for 96.1% of particles, and 73.1% of all filaments were transparent. Out of 40 random filaments from 10 specimens (one had indeterminate spectra patterns), 90% were polycarbonate, 50% were polyamide, and 40% were polypropylene.
Conclusion: Our study suggests that microplastics are ubiquitously present in the human colon.

Matched MeSH terms: Polycarboxylate Cement
Fulltext The microbiological quality of water from dental unit waterlines in Malaysian Armed Forces dental centres

Ma, Mei Siang, Zalini Yunus, Ahmad Razi Mohammad Yunus, Zukri Ahmad, Haryanti Toosa

Archives of Orofacial Sciences, 2012;7(1):1-7.
MyJurnal

Abstract Water quality in the dental unit waterlines (DUWLs) is important to the patients and dental health care personnel as they are at risk of being infected with opportunistic pathogens such as Pseudomonas or Legionella species. In this study, a total of 86 samples were collected from DUWLs of 19 dental units in 11 Malaysian Armed Forces dental centres (MAFDC). 350 ml water sample was collected in sterile thiosulphite bags from the outlets of 3–way syringe, high speed handpiece, scaler, cup filler, independent water reservoir or the tap of the same surgery respectively. Samples were transported to the laboratory within 24 hours and kept in the refrigerator at 40C. 100ml of each sample was filtered through a 0.45 μm polycarbonate membrane filter. The filter was then inoculated onto plate count agar and incubated at 370 C for 24 hours, after which the formed colonies were enumerated. Another separate 100ml of water sample was poured onto buffered charcoal yeast extract agar and cetrimide agar to culture Legionnella and Pseudomonas respectively. Identification of these bacteria were confirmed by polymerase chain reaction and sequencing. Pseudomonas aeruginosa was detected in 9.5% of the samples but Legionnella was not detected in any of the samples. 77% of the samples met American Dental Association (ADA) recommendation of less than 200 cfu/ml. The result of this study showed that it is difficult if not impossible to eliminate biofilm from the DUWLs. Regular monitor of water quality from DUWL is required to maximise the health of the dental patients and dental health care personnel.

Matched MeSH terms: Polycarboxylate Cement
Use of UV-vis-NIR spectroscopy to monitor label-free interaction between molecular recognition elements and erythropoietin on a gold-coated polycarbonate platform

Citartan M, Gopinath SC, Tominaga J, Chen Y, Tang TH

Talanta, 2014 Aug;126:103-9.
PMID: 24881539 DOI: 10.1016/j.talanta.2014.03.043

Label-free-based detection is pivotal for real-time monitoring of biomolecular interactions and to eliminate the need for labeling with tags that can occupy important binding sites of biomolecules. One simplest form of label-free-based detection is ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, which measure changes in reflectivity as a means to monitor immobilization and interaction of biomolecules with their corresponding partners. In biosensor development, the platform used for the biomolecular interaction should be suitable for different molecular recognition elements. In this study, gold (Au)-coated polycarbonate was used as a platform and as a proof-of-concept, erythropoietin (EPO), a doping substance widely abused by the athletes was used as the target. The interaction of EPO with its corresponding molecular recognition elements (anti-EPO monoclonal antibody and anti-EPO DNA aptamer) is monitored by UV-vis-NIR spectroscopy. Prior to this, to show that UV-vis-NIR spectroscopy is a suitable method for measuring biomolecular interaction, the interaction between biotin and streptavidin was demonstrated via this strategy and reflectivity of this interaction decreased by 25%. Subsequent to this, interaction of the EPO with anti-EPO monoclonal antibody and anti-EPO DNA aptamer resulted in the decrease of reflectivity by 5% and 10%, respectively. The results indicated that Au-coated polycarbonate could be an ideal biosensor platform for monitoring biomolecular interactions using UV-vis-NIR spectroscopy. A smaller version of the Au-coated polycarbonate substrates can be derived from the recent set-up, to be applied towards detecting EPO abuse among atheletes.

Matched MeSH terms: Polycarboxylate Cement/chemistry*