Displaying publications 21 - 40 of 50 in total

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  1. Huang XD, Liang JB, Tan HY, Yahya R, Long R, Ho YW
    J Agric Food Chem, 2011 Oct 12;59(19):10677-82.
    PMID: 21899359 DOI: 10.1021/jf201925g
    Depending on their source, concentration, chemical structure, and molecular weight, condensed tannins (CTs) form insoluble complexes with protein, which could lead to ruminal bypass protein, benefiting animal production. In this study, CTs from Leuceana leucocephala hybrid were fractionated into five fractions by a size exclusion chromatography procedure. The molecular weights of the CT fractions were determined using Q-TOF LC-MS, and the protein-binding affinities of the respective CT fractions were determined using a protein precipitation assay with bovine serum albumin (BSA) as the standard protein. The calculated number-average molecular weights (M(n)) were 1348.6, 857.1, 730.1, 726.0, and 497.1, and b values (the b value represents the CT quantity that is needed to bind half of the maximum precipitable BSA) of the different molecular weight fractions were 0.381, 0.510, 0.580, 0.636, and 0.780 for fractions 1, 2, 3, 4, and 5, respectively. The results indicated that, in general, CTs of higher molecular weight fractions have stronger protein-binding affinity than those of lower molecular weights. However, the number of hydroxyl units within the structure of CT polymers also affects the protein-binding affinity.
  2. Khor BH, Chinna K, Abdul Gafor AH, Morad Z, Ahmad G, Bavanandam S, et al.
    BMC Health Serv Res, 2018 Dec 04;18(1):939.
    PMID: 30514284 DOI: 10.1186/s12913-018-3702-9
    BACKGROUND: This study aimed to assess the situational capacity for nutrition care delivery in the outpatient hemodialysis (HD) setting in Malaysia by evaluating dietitian accessibility, nutrition practices and patients' outcomes.

    METHODS: A 17-item questionnaire was developed to assess nutrition practices and administered to dialysis managers of 150 HD centers, identified through the National Renal Registry. Nutritional outcomes of 4362 patients enabled crosscutting comparisons as per dietitian accessibility and center sector.

    RESULTS: Dedicated dietitian (18%) and visiting/shared dietitian (14.7%) service availability was limited, with greatest accessibility at government centers (82.4%) > non-governmental organization (NGO) centers (26.7%) > private centers (15.1%). Nutritional monitoring varied across HD centers as per albumin (100%) > normalized protein catabolic rate (32.7%) > body mass index (BMI, 30.7%) > dietary intake (6.0%). Both sector and dietitian accessibility was not associated with achieving albumin ≥40 g/L. However, NGO centers were 36% more likely (p = 0.030) to achieve pre-dialysis serum creatinine ≥884 μmol/L compared to government centers, whilst centers with dedicated dietitian service were 29% less likely (p = 0.017) to achieve pre-dialysis serum creatinine ≥884 μmol/L. In terms of BMI, private centers were 32% more likely (p = 0.022) to achieve BMI ≥ 25.0 kg/m2 compared to government centers. Private centers were 62% less likely (p 

  3. Leong ST, Liew SY, Khaw KY, Ahmad Hassali H, Richomme P, Derbré S, et al.
    Bioorg Chem, 2023 Dec;141:106859.
    PMID: 37742494 DOI: 10.1016/j.bioorg.2023.106859
    A bio-assay guided fractionation strategy based on cholinesterase assay combined with 13C NMR-based dereplication was used to identify active metabolites from the bark of Mesua lepidota. Eight compounds were identified with the aid of the 13C NMR-based dereplication software, MixONat, i.e., sitosterol (1), stigmasterol (2), α-amyrin (3), friedelin (6), 3β-friedelinol (7), betulinic acid (9), lepidotol A (10) and lepidotol B (11). Further bio-assay guided isolation of active compounds afforded one xanthone, pyranojacareubin (12) and six coumarins; lepidotol A (10), lepidotol B (11), lepidotol E (13), lepidotin A (14), and lepidotin B (15), including a new Mammea coumarin, lepidotin C (16). All the metabolites showed strong to moderate butyrylcholinesterase (BChE) inhibition. Lepidotin B (15) exhibited the most potent inhibition towards BChE with a mix-mode inhibition profile and a Ki value of 1.03 µM. Molecular docking and molecular dynamics simulations have revealed that lepidotin B (15) forms stable interactions with key residues within five critical regions of BChE. These regions encompass residues Asp70 and Tyr332, the acyl hydrophobic pocket marked by Leu286, the catalytic triad represented by Ser198 and His438, the oxyanion hole (OH) constituted by Gly116 and Gly117, and the choline binding site featuring Trp82. To gauge the binding strength of lepidotin B (15) and to pinpoint pivotal residues at the binding interface, free energy calculations were conducted using the Molecular Mechanics Generalized Born Surface Area (MM-GBSA) approach. This analysis not only predicted a favourable binding affinity for lepidotin B (15) but also facilitated the identification of significant residues crucial for the binding interaction.
  4. Lim CK, Lim JH, Ibrahim I, Chan YM, Zakaria NF, Yahya R, et al.
    Diagnostics (Basel), 2021 Sep 23;11(10).
    PMID: 34679443 DOI: 10.3390/diagnostics11101745
    Protein-energy wasting (PEW) is a devastating metabolic derangement that leads to increased morbidity and mortality in hemodialysis (HD) patients. This study aimed to determine the diagnostic test accuracy of bioelectrical impedance analysis derived-phase angle (PhA) in detecting PEW among HD patients. This was a multi-centre, cross-sectional study conducted amongst 152 multi-ethnic HD patients in Klang Valley, Malaysia. PEW was assessed using the International Society of Renal Nutrition and Metabolism criteria as the reference method. PhA was measured using a multi-frequency bioelectrical impedance spectroscopy at 50 kHz. Multiple and logistic regressions were used to determine factors associated with PhA and PEW diagnosis, respectively. A receiver operating characteristics curve analysis was used to establish the gender-specific PhA cut-offs to detect PEW. PEW existed in 21.1% of the HD patients. PhA was found as an independent predictor of PEW (adjOR = 0.308, p = 0.001), with acceptable to excellent discriminative performance (adjAUCmale = 0.809; adjAUCfemale = 0.719). Male patients had higher PhA cut-off compared to female patients (4.26° vs. 3.30°). We concluded that PhA is a valid and pragmatic biomarker to detect PEW in multi-ethnic Malaysian HD patients and a gender-specific cut-off is necessary, attributed to the gender differences in body composition.
  5. Loke SC, Kanesvaran R, Yahya R, Fisal L, Wong TW, Loong YY
    Ann Acad Med Singap, 2009 Dec;38(12):1074-80.
    PMID: 20052443
    INTRODUCTION: Intravenous calcium gluconate has been used to prevent postoperative hypocalcaemia (POH) following parathyroidectomy for secondary hyperparathyroidism in chronic kidney disease (CKD).

    MATERIALS AND METHODS: Retrospective data were obtained for 36 patients with CKD stage 4 and 5 after parathyroid surgery, correlating albumin-corrected serum calcium with the infusion rate of calcium gluconate. Calcium flux was characterised along with excursions out of the target calcium range of 2 to 3 mmol/L. With this data, an improved titration regimen was constructed.

    RESULTS: Mean peak efflux rate (PER) from the extracellular calcium pool was 2.97 mmol/h occurring 26.6 hours postoperatively. Peak calcium efflux tended to occur later in cases of severe POH. Eighty-one per cent of patients had excursions outside of the target calcium range of 2 to 3 mmol/L. Mean time of onset for hypocalcaemia was 2 days postoperatively. Hypocalcaemia was transient in 25% and persistent in 11% of patients.

    CONCLUSION: A simple titration regimen was constructed in which a 10% calcium gluconate infusion was started at 4.5 mL/h when serum calcium was <2 mmol/L, then increased to 6.5 mL/h and finally to 9.0 mL/h if calcium continued falling. Preoperative oral calcium and calcitriol doses were maintained. Blood testing was done 6-hourly, but when a higher infusion rate was needed, 4-hourly blood testing was preferred. Monitoring was discontinued if no hypocalcaemia developed in the fi rst 4 days after surgery. If hypocalcaemia persisted 6 days after surgery, then the infusion was stopped with further monitoring for 24 hours.

  6. M Zawawi SM, Yahya R, Hassan A, Mahmud HN, Daud MN
    Chem Cent J, 2013;7(1):80.
    PMID: 23634962 DOI: 10.1186/1752-153X-7-80
    Metal tungstates have attracted much attention due to their interesting structural and photoluminescence properties. Depending on the size of the bivalent cation present, the metal tungstates will adopt structures with different phases. In this work, three different phases of metal tungstates MWO4 (M= Ba, Ni and Bi) were synthesized via the sucrose templated method.
  7. 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.
  8. Mansoor MA, Ismail A, Yahya R, Arifin Z, Tiekink ER, Weng NS, et al.
    Inorg Chem, 2013 May 20;52(10):5624-6.
    PMID: 23627942 DOI: 10.1021/ic302772b
    Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.
  9. Naeem R, Ali Ehsan M, Yahya R, Sohail M, Khaledi H, Mazhar M
    Dalton Trans, 2016 Oct 14;45(38):14928-39.
    PMID: 27549401 DOI: 10.1039/c6dt02656g
    Pristine Mn2O3 and Ag-Mn2O3 composite thin films have been developed on fluorine doped tin oxide (FTO) coated glass substrates at 450 °C by aerosol assisted chemical vapor deposition (AACVD) using a methanol solution of a 1 : 2 mixture of acetatoargentate(i), Ag(CH3COO), and a newly synthesized manganese complex, [Mn(dmae)2(TFA)4] (1) (dmae = N,N-dimethylaminoethanolate, TFA = trifluoroacetate). The phase purity and stoichiometric composition of the films were investigated by X-ray diffraction (XRD) and Raman spectroscopy techniques. Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analyses revealed a Ag to Mn ratio of 1 : 2 and further confirmed the uniform dispersion of Ag nanoparticles into the Mn2O3 structure. Optical studies showed a direct band gap of 2.0 eV for the pristine Mn2O3 film that was lowered to 1.8 eV for Ag-Mn2O3 due to the plasmonic interaction of Ag with Mn2O3. The Ag-Mn2O3 composite film displayed enhanced photocatalytic activity in photoelectrochemical (PEC) water splitting and yielded a photocurrent of 3 mA cm(-2) at 0.7 V versus Ag/AgCl which was 1.6 times higher than a pristine Mn2O3 film alone, under AM 1.5 G illumination (100 mW cm(-2)). The high PEC efficiency is mainly due to the plasmonic effect of Ag nanoparticles, which enhances the visible light absorption, efficient electron-hole separation and high carrier mobility of the Ag-Mn2O3 photoelectrode. The charge carrier density of Ag-Mn2O3 is two times higher than the pristine Mn2O3 as calculated by the Mott-Schottky plot. Based on the PEC studies a mechanism is proposed to elucidate the high activity of Ag-Mn2O3 in PEC water splitting.
  10. Naji GA, Omar RA, Yahya R
    J Mech Behav Biomed Mater, 2017 03;67:135-143.
    PMID: 28006713 DOI: 10.1016/j.jmbbm.2016.12.007
    In all-ceramic systems, a high incidence of veneer chip-off has been reported in clinical studies. Coefficient of thermal expansion (CTE) behaviour is one of the factors that may increase residual stress in the interface and influence the veneer/core bond strength. Therefore, this study aimed to evaluate the effect of sodalite zeolite-infiltration on the CTE behaviour and bond strength of different all-ceramic prostheses. The case-study groups were synthesized sodalite zeolite-infiltrated alumina (IA-SOD) and synthesized sodalite zeolite-infiltrated zirconia-toughened alumina (ZTA) (IZ-SOD), while the control groups were glass-infiltrated alumina (IA-glass) and glass-infiltrated ZTA (IZ-glass). Forty cylindrical-shaped samples measuring 5 mm in diameter and 10 mm in height were tested for CTE using a thermo-mechanical analyser machine, and forty disc-shaped ceramic samples measuring 12 mm in diameter and 1.2 ± 0.2 mm in thickness were prepared using specially designed stainless steel split mould and veneered by cylinder-shaped (2 mm high × 2 mm diameter) low-fusing porcelain (Vita VM7). The veneer/core samples were sintered and tested for shear bond strength using a high precision universal testing machine. Scanning electron microscope, stereo microscope, atomic force microscope, and energy-dispersive X-ray spectroscopy were used to investigate the structural characteristics of samples at the fracture surface. The collected data were analyzed with a one-way ANOVA and Tukey HSD test (α=.05). IZ-SOD revealed highest CTE and shear bond strength values, while the IA-glass revealed the lowest values than the other groups. There was no significant difference in CTE and bond strength among IZ-SOD, IA-SOD and IZ-glass samples (p>0.05). The experimental SOD zeolite-infiltrated samples revealed higher CTE mismatch and bond strength along with a more favourable mode of failure than did the commercial glass-infiltrated samples. Sandblast technique is considered as effective conditioning procedure for enhancing the surface roughness of SOD zeolite-infiltrated frameworks which subsequently improving the bond strength.
  11. Ng YM, Lim YS, Ee LW, Fong VK, Low CL, Yee SY, et al.
    Transplant Proc, 2022 Jan 29.
    PMID: 35105465 DOI: 10.1016/j.transproceed.2022.01.002
    BACKGROUND: The Malaysian Kidney Allocation System implemented in 2020 includes only kidney transplant candidates with estimated posttransplant survival (EPTS) score of ≤20%, in replacement of Malaysian Organs Sharing System, which was based solely on dialysis vintage. We aim to compare the clinical outcomes of deceased-donor kidney transplant recipients (DDKTRs) with EPTS ≤20% to those with EPTS >20%.

    METHODS: All DDKTRs between January 1, 2015, and December 29, 2020, were included and categorized into 2 groups: EPTS ≤20% and EPTS >20%. Cox regression was performed to evaluate the association of EPTS score and patient survival. The rate of postoperative complications, graft failure and patient survival were compared between 2 groups. Data were analyzed with SPSS v26 and R v4.0.4. The study complies with the Helsinki Congress and the Istanbul Declaration.

    RESULTS: We included 159 DDKTRs, with a median follow-up of 25 months (range, 10-60 months). The mean age of those with EPTS ≤20% was 32.2 ± 3.4 years and those with EPTS >20% was 46.0 ± 6.7 years, and the median EPTS score were 16% (range, 12%-18%) and 38% (range, 27%-56.5%), respectively. EPTS score was associated with patient survival (hazard ratio, 1.031; 95% CI 1.010-1.052; P = .003), and the cutoff points of 30% and above were associated with worse survival. It showed good discrimination (C-index, 0.729; 95% CI 0.579-0.878; P = .003) and the optimal cutoff value was 38% (65.5% sensitivity, 68.8% specificity, 17.8% positive predictive value, and 95.8% negative predictive value). Both groups had similar rate of surgical complications (P = .191), graft failure (P = .503), and patient survival (P = .654), but those with EPTS >20% had higher incidence of urinary tract infection (9.3% vs 27.6%, P = .016).

    CONCLUSIONS: There was no difference in clinical outcomes using an EPTS cutoff point of 20% but worse patient survival if higher cutoff point was used.

  12. Rahbari, R., Hamdi, M., Farhudi, O., Yahya, R., Asmalina, M., Marzuki, Z.
    MyJurnal
    Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. In the case of titanium or titanium alloy materials, prior researches employed powder metallurgy technology for preparing metal matrix composites, MMCs and laminated structures through the use of fine powders of an inert phase or phases (TiC, TiN, TiB and TiB2B ) dispersed in Ti or Ti alloy powders. The present research relates to manufacture of titanium-ceramic composites that are synthesized by combustion synthesis (SHS) and retains a multilayered composite microstructure comprising one or more titanium-based layers and one ceramic titanium carbide layers.
  13. Rizwan M, Yahya R, Hassan A, Yar M, Azzahari AD, Selvanathan V, et al.
    Polymers (Basel), 2017 06 14;9(6).
    PMID: 30970902 DOI: 10.3390/polym9060225
    The authors wish to make a change to their published paper [1]. [...].
  14. Rizwan M, Yahya R, Hassan A, Yar M, Abd Halim AA, Rageh Al-Maleki A, et al.
    J Mater Sci Mater Med, 2019 Jun 11;30(6):72.
    PMID: 31187295 DOI: 10.1007/s10856-019-6273-3
    The success of wound healing depends upon the proper growth of vascular system in time in the damaged tissues. Poor blood supply to wounded tissues or tissue engineered grafts leads to the failure of wound healing or rejection of grafts. In present paper, we report the synthesis of novel organosoluble and pro-angiogenic chitosan derivative (CSD) by the reaction of chitosan with 1,3-dimethylbarbituric acid and triethylorthoformate (TEOF). The synthesized material was characterized by FTIR and 13C-NMR to confirm the incorporated functional groups and new covalent connectivities. Biodegradability of the synthesized chitosan derivative was tested in the presence of lysozyme and was found to be comparable with CS. The cytotoxicity and apoptosis effect of new derivative was determined against gastric adenocarcinoma (AGS) cells and was found to be non-toxic. The CSD was found to be soluble in majority of organic solvents. It was blended with polycaprolactone (PCL) to form composite scaffolds. From an ex ovo CAM assay, it was noted that CSD stimulated the angiogenesis.
  15. Sahathevan S, Karupaiah T, Khor BH, Sadu Singh BK, Mat Daud ZA, Fiaccadori E, et al.
    Front Nutr, 2021;8:743324.
    PMID: 34977109 DOI: 10.3389/fnut.2021.743324
    Background: Muscle wasting, observed in patients with end-stage kidney disease and protein energy wasting (PEW), is associated with increased mortality for those on hemodialysis (HD). Oral nutritional supplementation (ONS) and nutrition counseling (NC) are treatment options for PEW but research targeting muscle status, as an outcome metric, is limited. Aim: We compared the effects of combined treatment (ONS + NC) vs. NC alone on muscle status and nutritional parameters in HD patients with PEW. Methods: This multi-center randomized, open label-controlled trial, registered under ClinicalTrials.gov (Identifier no. NCT04789031), recruited 56 HD patients identified with PEW using the International Society of Renal Nutrition and Metabolism criteria. Patients were randomly allocated to intervention (ONS + NC, n = 29) and control (NC, n = 27) groups. The ONS + NC received commercial renal-specific ONS providing 475 kcal and 21.7 g of protein daily for 6 months. Both groups also received standard NC during the study period. Differences in quadriceps muscle status assessed using ultrasound (US) imaging, arm muscle area and circumference, bio-impedance spectroscopy (BIS), and handgrip strength (HGS) methods were analyzed using the generalized linear model for repeated measures. Results: Muscle indices as per US metrics indicated significance (p < 0.001) for group × time interaction only in the ONS + NC group, with increases by 8.3 and 7.7% for quadriceps muscle thickness and 4.5% for cross-sectional area (all p < 0.05). This effect was not observed for arm muscle area and circumference, BIS metrics and HGS in both the groups. ONS + NC compared to NC demonstrated increased dry weight (p = 0.039), mid-thigh girth (p = 0.004), serum prealbumin (p = 0.005), normalized protein catabolic rate (p = 0.025), and dietary intakes (p < 0.001), along with lower malnutrition-inflammation score (MIS) (p = 0.041). At the end of the study, lesser patients in the ONS + NC group were diagnosed with PEW (24.1%, p = 0.008) as they had achieved dietary adequacy with ONS provision. Conclusion: Combination of ONS with NC was effective in treating PEW and contributed to a gain in the muscle status as assessed by the US, suggesting that the treatment for PEW requires nutritional optimization via ONS.
  16. Selvanathan V, Azzahari AD, Abd Halim AA, Yahya R
    Carbohydr Polym, 2017 Jul 01;167:210-218.
    PMID: 28433156 DOI: 10.1016/j.carbpol.2017.03.023
    A first-of-its-kind, eco-friendly quasi-solid bioelectrolyte derived from potato starch was prepared. Starch was chemically modified via phthaloylation to synthesize amorphous, hydrophobic starch derivative and the attachment of the phthaloyl group was confirmed via FTIR which showed phthalate ester peak at 1715cm-1; and 1H NMR peaks between 7.30-7.90ppm attributed to the aromatic protons of the phthaloyl group. The resulting starch derivative was then infused with ternary natural deep eutectic solvent (NADES) made from different molar ratios of choline chloride, urea and glycerol. Electrochemical Impedance Spectroscopy (EIS) revealed that the highest ionic conductivity was obtained by the system consisting of NADES with choline chloride:urea:glycerol in molar ratios of 4:6:2, with a magnitude of 2.86mScm-1, hence validating the prospects of the materials to be further experimented as an alternative electrolyte in various electrochemical devices.
  17. Selvanathan V, Yahya R, Ruslan MH, Sopian K, Amin N, Nour M, et al.
    Polymers (Basel), 2020 Feb 27;12(3).
    PMID: 32120814 DOI: 10.3390/polym12030516
    This work is a pioneer attempt to fabricate quasi-solid dye-sensitized solar cell (QSDDSC) based on organosoluble starch derivative. Rheological characterizations of the PhSt-HEC blend based gels exhibited viscoelastic properties favorable for electrolyte fabrication. From amplitude sweep and tack test analyses, it was evident that the inclusion of LiI improved the rigidity and tack property of the gels. On the other hand, the opposite was true for TPAI based gels, which resulted in less rigid and tacky electrolytes. The crystallinity of the gels was found to decline with increasing amount of salt in both systems. The highest photoconversion efficiency of 3.94% was recorded upon addition of 12.5 wt % TPAI and this value is one of the highest DSSC performance recorded for starch based electrolytes. From electrochemical impedance spectroscopy (EIS), it is deduced that the steric hindrance imposed by bulky cations aids in hindering recombination between photoanode and electrolyte.
  18. Shahabudin N, Yahya R, Gan SN
    Polymers (Basel), 2016 Apr 06;8(4).
    PMID: 30979216 DOI: 10.3390/polym8040125
    One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde) (PMUF) microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemical properties of core and shell materials were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimetry (DSC) analysis showed a glass transition around -15 °C due to the alkyd, and a melting temperature at around 200 °C due to the shell. Thermogravimetric analysis (TGA) results showed that the core and shell thermally degraded within the temperature range of 200⁻600 °C. Field emission scanning electron microscope (FESEM) examination of the ruptured microcapsule showed smooth inner and rough outer surfaces of the shell. Flexural strength and microhardness (Vickers) of the cured epoxy compound were not affected with the incorporation of 1%⁻3% of the microcapsules. The viability of the healing reactions was demonstrated by blending small amounts of alkyd with epoxy and hardener at different ratios. The blends could readily cure to non-sticky hard solids at room temperature and the reactions could be verified by ATR-FTIR.
  19. Sim LH, Gan SN, Chan CH, Yahya R
    Spectrochim Acta A Mol Biomol Spectrosc, 2010 Aug;76(3-4):287-92.
    PMID: 20444642 DOI: 10.1016/j.saa.2009.09.031
    The interaction behaviours between components of polyacrylate (PAc)/poly(ethylene oxide) (PEO) and lithium perchlorate (LiClO(4)) were investigated in detail by Attenuated Total Reflectance (ATR)-Fourier Transformed Infrared (FTIR) spectroscopy. Solution cast films of the PAc/PEO and PAc/PEO/LiClO(4) were examined. No obvious shifting of the characteristic ether and ester group stretching modes of PEO and PAc was observed, indicating incompatibility of the binary PAc/PEO blend. The spectroscopic studies on the PAc/PEO/LiClO(4) blends reveal that Li(+) ions coordinate individually to the polymer components at the ether oxygen of PEO and the C-O of the ester group of PAc. Frequency changes observed on the nu(C-O-C) and omega(CH(2)) of PEO confirm the coordination between PEO and Li(+) ions resulting in crystallinity suppression of PEO. The absence of experimental evidence on the formation of PEO-Li(+)-PAc complexes suggests that LiClO(4) does not enhance the compatibility of PAc/PEO blend.
  20. Soume BB, Yahya R, Gan SN, Ng SW
    PMID: 21201619 DOI: 10.1107/S1600536808025798
    In the crystal structure of the title compound, [Cr(3)(C(2)Cl(3)O(2))(7)O(H(2)O)(2)]·3CH(3)CN, the trinuclear [Cr(3)O(H(2)O)(2)(Cl(3)CCO(2))(7)] mol-ecule has an oxide O atom that is connected to one monodentate trichloro-acetate-coordinated and two water-coordinated Cr(III) atoms, the three metal atoms forming the points of an equilateral triangle. Each of the six remaining carboxyl-ate groups bridges a Cr-O-Cr fragment. The cluster inter-acts with the three solvent mol-ecules through water-acetonitrile O-H⋯N hydrogen bonds. Adjacent clusters are linked by a water-carboxylate O-H⋯O hydrogen bond to give a helical chain. One of the CCl(3) groups was found to be disordered over two positions, with the major component having a site-occupancy factor of 0.64 (1).
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