Displaying publications 1 - 20 of 317 in total

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  1. Ab Aziz NA, Salim N, Zarei M, Saari N, Yusoff FM
    Prep Biochem Biotechnol, 2021;51(1):44-53.
    PMID: 32701046 DOI: 10.1080/10826068.2020.1789991
    The study was conducted to determine anti-tyrosinase and antioxidant activities of the extracted collagen hydrolysate (CH) derived from Malaysian jellyfish, Rhopilema hispidum. Collagen was extracted using 1:1 (w:v) 0.1 M NaOH solution at temperature 25 °C for 48 hr followed by treatment of 1:2 (w:v) distilled water for another 24 hr and freeze-dried. The extracted collagen was hydrolyzed using papain at optimum temperature, pH and enzyme/substrate ratio [E/S] of 60 °C, 7.0 and 1:50, respectively. CH was found to exhibit tyrosinase inhibitory activity, DPPH radical scavenging and metal ion-chelating assays up to 64, 28, and 83%, respectively, after 8 hr of hydrolysis process. The molecular weight of CH was found <10 kDa consisting of mainly Gly (19.219%), Glu (10.428%), and Arg (8.848%). The UV-visible spectrum analysis showed a major and minor peak at 218 and 276 nm, accordingly. The FTIR spectroscopy confirmed the amide groups in CH. The SEM images demonstrated spongy and porous structure of CH. In the cytotoxicity study, CH has no cytotoxicity against mouse embryonic 3T3 fibroblast cell line with IC50 value >500 µg/ml. Results revealed that the CH generated from this study has a potential to be developed as active ingredient in cosmeceutical application.
    Matched MeSH terms: Molecular Weight
  2. Abd Jalil SN, Wang DK, Yacou C, Motuzas J, Smart S, Diniz da Costa JC
    Materials (Basel), 2016 Nov 18;9(11).
    PMID: 28774057 DOI: 10.3390/ma9110938
    This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by exposure to a vacuum between 30 and 1200 s and then calcined at 400 °C. X-ray diffraction and nitrogen adsorption analyses showed that the crystallite size and particle size of titania increased as a function of vacuum time. All the TM membranes were mesoporous with an average pore diameter of ~3.6 nm with an anatase crystal morphology. Water, glucose, sucrose, and polyvinylpyrrolidone with 40 and 360 kDa (PVP-40 kDa and PVP-360 kDa) were used as feed solutions for MW cut-off and hexadecane solution for oil filtration investigation. The TM membranes were not able to separate glucose and sucrose, thus indicating the membrane pore sizes are larger than the kinetic diameter of sucrose of 0.9 nm, irrespective of vacuum exposure time. They also showed only moderate rejection (20%) of the smaller PVP-40 kDa, however, all the membranes were able to obtain an excellent rejection of near 100% for the larger PVP-360 kDa molecule. Furthermore, the TM membranes were tested for the separation of oil emulsions with a high concentration of oil (3000 ppm), reaching high oil rejections of more than 90% of oil. In general, the water fluxes increased with the vacuum exposure time indicating a pore structural tailoring effect. It is therefore proposed that a mechanism of pore size tailoring was formed by an interconnected network of Ti-O-Ti nanoparticles with inter-particle voids, which increased as TiO₂ nanoparticle size increased as a function of vacuum exposure time, and thus reduced the water transport resistance through the TM membranes.
    Matched MeSH terms: Molecular Weight
  3. Abdualkader AM, Ghawi AM, Alaama M, Awang M, Merzouk A
    Pak J Pharm Sci, 2013 May;26(3):525-35.
    PMID: 23625426
    The medicinal Malaysian leeches have been used in traditional medicine to treat many different ailments. In this study, leech saliva extract (LSE) was collected from the medicinal Malaysian leech Hirudinaria manillensis. Gel electrophoresis of LSE was carried out to estimate the peptide and protein molecular weights of its content. Results showed that LSE contains more than 60 peptides and proteins with molecular masses ranging from 1.9-250kDa. Thrombin time assay in vitro was employed to assess the collected LSE antithrombin activity. First, to study its stability, LSE was lyophilized under the following different conditions: pre-freezing temperature, type of container and lyophilization cycle. Pre-freezed LSE sample at -20°C and lyophilized for 24 hours retained about 100-95% of its original biological activities. Second, the LSE antithrombin activity was monitored for a period of six months. Storage temperature, type of the container and photosensitivity effects on antithrombin activity of the lyophilized (solid state) and non-lyophilized (liquid state) were investigated. Results showed that storage temperature drastically affected the biological activity of LSE with -20 °C as the optimum temperature. Samples stored at ambient temperature and +4 °C were light photosensitive and adversely affected when stored in polypropylene tubes. Lyophilized samples were more stable than non-lyophilized ones over the period of study. To sum up, in order to have a biologically active stock of LSE, it has to be lyophilized for no more than 24 hours following freezing at -20°C and has to be stored at -20°C in glass tubes protected from light.
    Matched MeSH terms: Molecular Weight
  4. Abdul Aziz NFH, Abbasiliasi S, Ng ZJ, Abu Zarin M, Oslan SN, Tan JS, et al.
    Molecules, 2020 Nov 16;25(22).
    PMID: 33207534 DOI: 10.3390/molecules25225332
    Lactobacillus bulgaricus is a LAB strain which is capable of producing bacteriocin substances to inhibit Staphylococcus aureus. The aim of this study was to purify a bacteriocin-like inhibitory substance (BLIS) produced by L. bulgaricus FTDC 1211 using an aqueous impregnated resins system consisting of polyethylene-glycol (PEG) impregnated on Amberlite XAD4. Important parameters influencing on purification of BLIS, such as the molecular weight and concentration of PEG, the concentration and pH of sodium citrate and the concentration of sodium chloride, were optimized using a response surface methodology. Under optimum conditions of 11% (w/w) of PEG 4000 impregnated Amberlite XAD4 resins and 2% (w/w) of sodium citrate at pH 6, the maximum purification factor (3.26) and recovery yield (82.69% ± 0.06) were obtained. These results demonstrate that AIRS could be used as an alternate purification system in the primary recovery step.
    Matched MeSH terms: Molecular Weight
  5. Abdul-Rahman PS, Lim BK, Hashim OH
    Electrophoresis, 2007 Jun;28(12):1989-96.
    PMID: 17503403
    The expression of high-abundance serum proteins in newly diagnosed patients with endometrial adenocarcinoma (EACa), squamous cell cervical carcinoma (SCCa) and cervical adenocarcinoma (ACCa), relative to control female subjects, was analyzed by subjecting serum samples to 2-DE followed by image analysis of the silver-stained protein profiles. The three cohorts of cancer patients demonstrated different altered expression of serum high-abundance proteins compared to negative control women. The expression of alpha1-antitrypsin, alpha1-B glycoprotein, cleaved high-molecular-weight kininogen (light chain) and antithrombin III were consistently altered in all the patients. However, clusterin was upregulated only in the patients with EACa, while those with SCCa and ACCa were typically characterized by the upregulated expression of zinc alpha-2-glycoprotein. The aberrant expression of selective serum proteins in the various cohorts of cancer patients was validated by competitive ELISA as well as by lectin detection. Analysis by using the champedak galactose binding lectin further highlighted an unidentified protein that may be differently glycosylated in the sera of the EACa patients that were studied.
    Matched MeSH terms: Kininogen, Low-Molecular-Weight
  6. Abdullah AZ, Ling PY
    J Hazard Mater, 2010 Jan 15;173(1-3):159-67.
    PMID: 19740600 DOI: 10.1016/j.jhazmat.2009.08.060
    The ambient sonocatalytic degradation of congo red, methyl orange, and methylene blue by titanium dioxide (TiO(2)) catalyst at initial concentrations between 10 and 50mg/L, catalyst loadings between 1.0 and 3.0mg/L and hydrogen peroxide (H(2)O(2)) concentrations up to 600 mg/L is reported. A 20 kHz ultrasonic processor at 50 W was used to accelerate the reaction. The catalysts were exposed to heat treatments between 400 and 1000 degrees C for up to 4h to induce phase change. Sonocatalysts with small amount of rutile phase showed better sonocatalytic activity but excessive rutile phase should be avoided. TiO(2) heated to 800 degrees C for 2h showed the highest sonocatalytic activity and the degradation of dyes was influenced by their chemical structures, chemical phases and characteristics of the catalysts. Congo red exhibited the highest degradation rate, attributed to multiple labile azo bonds to cause highest reactivity with the free radicals generated. An initial concentration of 10mg/L, 1.5 g/L of catalyst loading and 450 ppm of H(2)O(2) gave the best congo red removal efficiency of above 80% in 180 min. Rate coefficients for the sonocatalytic process was successfully established and the reused catalyst showed an activity drop by merely 10%.
    Matched MeSH terms: Molecular Weight
  7. Abedin MZ, Karim AA, Latiff AA, Gan CY, Ghazali FC, Barzideh Z, et al.
    Nat Prod Res, 2014;28(16):1302-5.
    PMID: 24670209 DOI: 10.1080/14786419.2014.900617
    The molecular mass distribution, amino acid composition and radical-scavenging activity of collagen hydrolysates prepared from collagen isolated from the sea cucumber Stichopus vastus were investigated. β and α1 chains of the collagen were successfully hydrolysed by trypsin. The molecular mass distribution of the hydrolysates ranged from 5 to 25 kDa, and they were rich in glycine, alanine, glutamate, proline and hydroxyproline residues. The hydrolysates exhibited excellent radical-scavenging activity. These results indicate that collagen hydrolysates from S. vastus can be used as a functional ingredient in food and nutraceutical products.
    Matched MeSH terms: Molecular Weight
  8. Abedin MZ, Karim AA, Ahmed F, Latiff AA, Gan CY, Che Ghazali F, et al.
    J Sci Food Agric, 2013 Mar 30;93(5):1083-8.
    PMID: 22936269 DOI: 10.1002/jsfa.5854
    Sea cucumber (Stichopus vastus) is considered an underutilized resource, since only its stomach and intestines are eaten raw as salad in a few countries and the remaining parts, especially the integument rich in collagen, is discarded. Hence a valuable by-product having potential nutraceutical and pharmaceutical applications is wasted. In the present investigation, pepsin-solubilized collagen (PSC) from the integument of S. vastus was isolated, purified and characterized.
    Matched MeSH terms: Molecular Weight
  9. Abedinia A, Ariffin F, Huda N, Nafchi AM
    Int J Biol Macromol, 2017 May;98:586-594.
    PMID: 28174080 DOI: 10.1016/j.ijbiomac.2017.01.139
    The effects of different pretreatments on yield and composition of extraction, physicochemical, and rheological properties of duck feet gelatin (DFG) were investigated. Gelatins were extracted from the whole feet of Pekin duck with an average yield of 4.09%, 3.65%, and 5.75% for acidic (Ac-DFG), alkaline (Al-DFG), and enzymatic (En-DFG) pretreatment on a wet weight basis, respectively. Proteins at 81.38%, 79.41%, 82.55%, and 87.38% were the major composition for Ac-DFG, Al-DFG, En-DFG, and bovine, respectively. Amino acid analysis showed glycine as the predominant amino acid in Ac-DFG, followed by hydroxyproline, proline, and alanine for Ac-DFG, Al-DFG, and En-DFG, respectively. Rheological analysis indicated that the maximum elastic modulus (9972.25Pa) and loss modulus (4956.28Pa) for Ac-DFG gelatin were significantly higher than those of other gelatins. Extracted gelatins contained α1 and α2 chains as the predominant components, and enzymatic gelatin had low molecular weight peptides. Fourier transform infrared spectroscopy showed that the peak of the gelatins was mainly positioned in the amide band region (amides I, II, and III). A considerable loss of molecular-order triple helical structure was also observed after pepsin treatment. In summary, duck feet gelatin has potential to replace as mammalian gelatin in food and pharmaceutical industry.
    Matched MeSH terms: Molecular Weight
  10. Abo-Shakeer, L.K.A., Yakasai, M.H., Rahman, M.F., Syed, M.A., Bakar, N.A., Othman, A.R.
    MyJurnal
    Molybdenum is an emerging pollutant. Bioremediation of this heavy metal is possible by the
    mediation of Mo-reducing bacteria. These bacteria contain the Mo-reducing enzymes that can
    conver toxic soluble molybdenum into molybdenum blue; a less soluble and less toxic form of the
    metal. To date only the enzyme has been purified from only one bacterium. The aim of this study is
    to purify the Mo-reducing enzyme from a previously isolated Mo-reducing bacterium Bacillus
    pumilus strain Lbna using ammonium sulphate fractionation followed by ion exchange and then
    gel filtration. Two clear bands were obtained after the gel filtration step with molecular weights
    of 70 and 100 kDa. This indicates that further additional purification methods need to be used
    to get a purified fraction. Hence, additional steps of chromatography such as hydroxyapatite or
    chromatofocusing techniques can be applied in the future.
    Matched MeSH terms: Molecular Weight
  11. Abu Tawila ZM, Ismail S, Dadrasnia A, Usman MM
    Molecules, 2018 Oct 18;23(10).
    PMID: 30340415 DOI: 10.3390/molecules23102689
    The production, optimization, and characterization of the bioflocculant QZ-7 synthesized by a novel Bacillus salmalaya strain 139SI isolated from a private farm soil in Selangor, Malaysia, are reported. The flocculating activity of bioflocculant QZ-7 present in the selected strain was found to be 83.3%. The optimal culture for flocculant production was achieved after cultivation at 35.5 °C for 72 h at pH 7 ± 0.2, with an inoculum size of 5% (v/v) and sucrose and yeast extract as carbon and nitrogen sources. The maximum flocculating activity was found to be 92.6%. Chemical analysis revealed that the pure bioflocculant consisted of 79.08% carbohydrates and 15.4% proteins. The average molecular weight of the bioflocculant was calculated to be 5.13 × 10⁵ Da. Infrared spectrometric analysis showed the presence of carboxyl (COO-), hydroxyl (-OH), and amino (-NH₂) groups, polysaccharides and proteins. The bioflocculant QZ-7 exhibited a wide pH stability range from 4 to 7, with a flocculation activity of 85% at pH 7 ± 0.2. In addition, QZ-7 was thermally stable and retained more than 80% of its flocculating activity after being heated at 80 °C for 30 min. SEM analysis revealed that QZ-7 exhibited a clear crystalline brick-shaped structure. After treating wastewater, the bioflocculant QZ-7 showed significant flocculation performance with a COD removal efficiency of 93%, whereas a BOD removal efficiency of 92.4% was observed in the B. salmalaya strain 139SI. These values indicate the promising applications of the bioflocculant QZ-7 in wastewater treatment.
    Matched MeSH terms: Molecular Weight
  12. AbuBakar S
    JUMMEC, 1996;1:21-24.
    The effects of human cytomegalovirus (HCMV) infection on human fibroblast cell genomes were investigated using agarose gel electrophoresis. At selected intervals post-infection (PI), cellular D N A from mock-treated and HCMV-infected cells were prepared in low melting point agarose plugs. Results obtained following electrophoresis of the cellular D N A indicate that HCMV infection did not result in extensive degradation of the cellular DNA, even in samples obtained from cells which showed > 95% cytopathologic effects. High molecular weight DNA (> 23 Kb) comparable to that of the mock-treated samples were noted in a l l HCMV infected DNA samples. Digestion of the DNA samples with restriction endonucleases, EcoR I, Not I, Sfi I, and Nru I, however, resulted in the appearance of smaller DNA fragments (< 23 Kb) in samples obtained on day 3, 4, and 5 PI. Since these DNA bands appeared only in the infected cells, it was likely that these were the HCMV genomic DNA fragments. Findings presented in this study support the notion that the cellular DNA of HCMVinfected cells could remained intact and functiona. KEYWORDS: Cytomegalovirus, chromosomes, DNA, genomes, restriction enzymes
    Matched MeSH terms: Molecular Weight
  13. Adeyemi, K.D., Mislan, N., Aghwan, Z.A., Sarah, S.A., Sazili, A.Q.
    MyJurnal
    The study examined the protein profile of Pectoralis major muscle in broiler chickens subjected to different freezing and thawing methods. Pectoralis major muscle was excised from the carcasses of twenty broiler chickens and split into left and right halves. The left half was subjected to slow freezing (-20oC) while the right half was rapidly frozen (-80oC). The samples were stored at their respective temperature for 2 weeks and assigned to either of tap water (27oC, 30 min), room temperature (26oC, 60 min), microwave (750W, 10 min) or chiller (4oC, 6 h) thawing. Changes in myofibrillar proteins following the thawing methods were monitored through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The electrophoretic profile indicated differences (p < 0.05) in intensities of the components of myofibrillar proteins among the thawing methods in both slow and rapidly frozen samples. Chiller thawing had significantly higher (p < 0.05) protein concentration than other methods in rapidly frozen samples. However, in slow freezing, there were no significant differences in protein concentration among the thawing methods. In rapidly frozen samples, the protein optical densities at molecular weight of 21, 27, 55 and 151kDa in tap water, chiller and room temperature thawing did not differ (p < 0.05). Similarly, in slowly frozen samples, protein optical densities at molecular weight of 21, 27, 85 and 151 kDa were not significantly different among chill, tap water and room temperature thawing. Microwave thawing consistently caused higher protein degradation resulting in significantly lower (p < 0.05) protein quality and quantity in both freezing methods.
    Matched MeSH terms: Molecular Weight
  14. Aidah Jumahat, Napisah Sapiai, Eliya Farah Hana Mohd Kamal
    MyJurnal
    This paper investigates the effect of acid and silane treatment of Carbon Nanotubes (CNT) on wear properties of epoxy polymer composite. The wear test done was based on ASTM D3389 standard using the Abrasive Wear Tester (TR 600). Characterisation analysis was also done using Transmission Electron Microscopy (TEM) in order to study the dispersion of the CNT inside the epoxy matrix. When untreated CNT was added to the epoxy with amounts of 0.5, 0.75 and 1.0 wt%, the wear rates did not improve except for 0.5 wt% CNT filled epoxy. This was due to the lack of dispersion which causes larger chunks of material being dug out, thus contributing to a higher mass loss and wear rate. When treated with acid and silane, 0.75 wt% and 1.0 wt% CNT filled epoxy composites showed improvement. The TEM images of 0.5 wt%, 0.75 wt% and 1.0 wt% PCNT filled epoxy supported the claim of the lack of dispersion of PCNT inside the epoxy.
    Matched MeSH terms: Molecular Weight
  15. Ainun Zuriyati Mohamed, Sarani Zakaria, Roslinda Shamsuddin, Mustaffa Abdullah
    This paper reports on the preparation of magnetic lumen loaded handsheets from bleached and unbleached mixed tropical hardwood kraft pulps. The lumen coating technique is a physical approach whereby fillers were deposited inside the fibre lumen. In order to produce magnetically responsive fibres, magnetic fillers were loaded into the fibre lumen. The magnetic filler chosen was magnetite which is usually used to make mylar as found in a diskette. Low and high molecular weights of polyacrylamide (PAM) were used as retention aids. The effect of different molecular weight of PAM on filler content in the bleached and unbleached handsheets were studied. The results showed that the amount of fillers deposited in the pulp fibres increased with increasing molecular weight of PAM using both pulps. However the bleached pulps gave better lumen loading than the unbleached when using high molecular weight of PAM.
    Matched MeSH terms: Molecular Weight
  16. Aiyede M, Lim XY, Russell AAM, Patel RP, Gueven N, Howells DW, et al.
    J Neurotrauma, 2023 Jan;40(1-2):4-21.
    PMID: 35880422 DOI: 10.1089/neu.2022.0020
    The identification of effective pharmacotherapies for traumatic brain injury (TBI) remains a major challenge. Treatment with heparin and its derivatives is associated with neuroprotective effects after experimental TBI; however, the optimal dosage and method of administration, modes of action, and effects on hemorrhage remain unclear. Therefore, this review aimed to systematically evaluate, analyze, and summarize the available literature on the use of heparin and low molecular weight heparins (LMWHs) as treatment options for experimental TBI. We searched two online databases (PubMed and ISI Web of Science) to identify relevant studies. Data pertaining to TBI paradigm, animal subjects, drug administration, and all pathological and behavior outcomes were extracted. Eleven studies met our pre-specified inclusion criteria, and for outcomes with sufficient numbers, data from seven publications were analyzed in a weighted mean difference meta-analysis using a random-effects model. Study quality and risk of bias were also determined. Meta-analysis revealed that heparin and its derivatives decreased brain edema, leukocyte rolling, and vascular permeability, and improved neurological function. Further, treatment did not aggravate hemorrhage. These findings must be interpreted with caution, however, because they were determined from a limited number of studies with substantial heterogeneity. Also, overall study quality was low based on absences of data reporting, and potential publication bias was identified. Importantly, we found that there are insufficient data to evaluate the variables we had hoped to investigate. The beneficial effects of heparin and LMWHs, however, suggest that further pre-clinical studies are warranted.
    Matched MeSH terms: Heparin, Low-Molecular-Weight/pharmacology; Heparin, Low-Molecular-Weight/therapeutic use
  17. Akanbi, T.O., Kamaruzaman, A.L., Abu Bakar, F., Sheikh Abdul Hamid, N., Radu, S., Abdul Manap, M.Y., et al.
    MyJurnal
    The activities of lipase produced by five lipases-producing thermophilic bacteria strains (SY1, SY5, SY6, SY7 and SY9) isolated from Selayang Hot Spring in the western part of Peninsular Malaysia were analyzed and compared. SY7 and SY9 had considerably higher lipolytic activities than those of SY1, SY5 and SY6. Thermostabilities of lipase produced by all strains were determined after heating at 80°C for 30 minutes. Strain SY7 retained the highest lipolytic activity of 77%, while others had infinitesimally low thermostability (retaining less than 34% of their original activity) at the same temperature and time. SY7 was chosen for further characterization because it showed exceptionally high lipase activity and thermostability. It was identified as belonging to Bacillus species by the conventional Gram-staining technique, Biochemical tests and Biolog Microstation system. By using 16S rRNA gene sequencing, strain SY7 generated the same expected PCR product with molecular weight of 1500 base pair. It displayed 98% sequence similarity to Bacillus cereus strain J-1 16S rRNA gene partial sequence with accession number: AY305275 and has been deposited in the database of Genbank.
    Matched MeSH terms: Molecular Weight
  18. Akbari S, Mahmood SM, Ghaedi H, Al-Hajri S
    Polymers (Basel), 2019 Jun 14;11(6).
    PMID: 31207965 DOI: 10.3390/polym11061046
    Copolymers of acrylamide with the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid-known as sulfonated polyacrylamide polymers-had been shown to produce very promising results in the enhancement of oil recovery, particularly in polymer flooding. The aim of this work is to develop an empirical model through the use of a design of experiments (DOE) approach for bulk viscosity of these copolymers as a function of polymer characteristics (i.e., sulfonation degree and molecular weight), oil reservoir conditions (i.e., temperature, formation brine salinity and hardness) and field operational variables (i.e., polymer concentration, shear rate and aging time). The data required for the non-linear regression analysis were generated from 120 planned experimental runs, which had used the Box-Behnken construct from the typical Response Surface Methodology (RSM) design. The data were collected during rheological experiments and the model that was constructed had been proven to be acceptable with the Adjusted R-Squared value of 0.9624. Apart from showing the polymer concentration as being the most important factor in the determination of polymer solution viscosity, the evaluation of the model terms as well as the Sobol sensitivity analysis had also shown a considerable interaction between the process parameters. As such, the proposed viscosity model can be suitably applied to the optimization of the polymer solution properties for the polymer flooding process and the prediction of the rheological data required for polymer flood simulators.
    Matched MeSH terms: Molecular Weight
  19. Akbari S, Mahmood SM, Tan IM, Ghaedi H, Ling OL
    Polymers (Basel), 2017 Nov 27;9(12).
    PMID: 30965947 DOI: 10.3390/polym9120647
    This research aims to test four new polymers for their stability under high salinity/high hardness conditions for their possible use in polymer flooding to improve oil recovery from hydrocarbon reservoirs. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; SUPERPUSHER SAV55; THERMOASSOCIATIF; and AN132 VHM which are basically sulfonated polyacrylamide copolymers of AM (acrylamide) with AMPS (2-Acrylamido-2-Methylpropane Sulfonate). AN132 VHM has a molecular weight of 9⁻11 million Daltons with 32 mol % degree of sulfonation. SUPERPUSHER SAV55 mainly has about 35 mol % sulfonation degree and a molecular weight of 9⁻11 million Daltons. FLOCOMB C7035, in addition, has undergone post-hydrolysis step to increase polydispersity and molecular weight above 18 million Daltons but it has a sulfonation degree much lower than 32 mol %. THERMOASSOCIATIF has a molecular weight lower than 12 million Daltons and a medium sulfonation degree of around 32 mol %, and also contains LCST (lower critical solution temperature) type block, which is responsible for its thermoassociative characteristics. This paper discusses the rheological behavior of these polymers in aqueous solutions (100⁻4500 ppm) with NaCl (0.1⁻10 wt %) measured at 25 °C. The effect of hardness was investigated by preparing a CaCl₂-NaCl solution of same ionic strength as the 5 wt % of NaCl. In summary, it can be concluded that the rheological behavior of the newly modified co-polymers was in general agreement to the existing polymers, except that THERMOASSOCIATIF polymers showed unique behavior, which could possibly make them a better candidate for enhanced oil recovery (EOR) application in high salinity conditions. The other three polymers, on the other hand, are better candidates for EOR applications in reservoirs containing high divalent ions. These results are expected to be helpful in selecting and screening the polymers for an EOR application.
    Matched MeSH terms: Molecular Weight
  20. Al-Dulaimi AA, Shahrir Hashim, Khan M
    Sains Malaysiana, 2011;40:1179-1186.
    Two inorganic pigments (TiO2 and SiO2) were used to prepare composites with polyaniline (PANI) by situ polymerization method. PANI and PANI composites with SiO2 and TiO2 were characterized using Fourier transform infrared spectroscopy and X-ray diffraction. The morphology of the synthesized pigments (PANI , PANI-SiO2 and PANI-TiO2) was examined using scanning electron microscopy. Samples were then used as pigments through blending them with acrylic paint and applied on the surface of carbon steel panels. Corrosion was evaluated for coating of carbon steel panels through full immersion test up to standard ASTMG 31. Mass loss was calculated after they have been exposed in acidic media. A digital camera was also used for monitoring corrosion visually on the surface of carbon steel specimens. The results revealed that acrylic paint pigmented by PANI-SiO2 composite was more efficient in corrosion protection for carbon steel compared with the other synthesized pigments.
    Matched MeSH terms: Molecular Weight
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