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81.
Sulaiman Wadi Harun Nizam Tamchek Mohd Kamil Abd-Rahman Prabakaran Poopalan Harith Ahmad 《Optical Review》2003,10(3):133-135
A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm. 相似文献
82.
Photodynamic therapy (PDT) selectivity and specificity can be improved by binding the photosensitizers to target receptors. One approach is to cross-link porphyrins to a biological target receptor via the photocleavable o-nitrobenzyl linker, where a controlled released of the porphyrin can be monitored upon irradiation. The synthetic pathways involved esterification of a porphyrin-carboxylic acid and a unit containing the o-nitrobenzyl alcohol moiety and the bioconjugate. Reactions of a model porphyrin and o-nitrobenzyl alcohol using the carbonyl activating carbodiimide reagent DCC gave a stable N-acyl urea porphyrin, whereas use of EDAC (1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride) gave the desired compounds. Further studies were carried out on the attachment of carbohydrates (i.e., potentially receptor binding ligands) through such a linker to porphyrins. Preliminary irradiation experiments of such a compound show that upon UV irradiation (350 nm) for 80 min, approximately 50% of the porphyrin was cleaved to release the carboxylic acid porphyrin photosensitizer indicating the utility of such systems as photosensitizers delivery systems. 相似文献
83.
Mohd. Sajid Ali Mohd. Suhail Goutam Ghosh Mohammad Kamil Kabir-ud-Din 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,350(1-3):51-56
The interaction between bis(hexadecyldimethylammonium)hexane dibromide (16-6-16), bis(tetradecyldimethylammonium)hexane dibromide (14-6-14), their conventional counterparts cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) with polyvinylpyrrolidone (PVP) was investigated using the conductivity technique. The results show that gemini surfactants interact strongly with PVP as compared to conventional surfactants. The results also reveal that the surfactants with shorter hydrocarbon chain interact weakly as those of longer hydrocarbon chain. The interactions of 16-6-16 and 14-6-14 and their conventional counterparts with PVP were also studied using dynamic light scattering (DLS) measurements. We have also highlighted the effect of surfactant–polymer interactions on the dispersion force in the solution. Critical aggregation concentration (cac) and critical micelle concentration (cmc) were obtained using the conductivity data. The degrees of micelle ionization and free energies associated with aggregation, micellization, and transfer have also been evaluated and discussed. 相似文献
84.
Juahir Yusnita Subramaniam Puvaneswary Hapipah Mohd. Ali Ward T. Robinson Thong Kwai-Lin 《Polyhedron》2009,28(14):3050-3054
2,6-Diacetylpyridine bis(benzenesulfonohydrazide) Schiff bases (L1, L2 and L3) and their Cu(II) complexes of the general formula [CuL·H2O] were synthesized and characterized by various spectroscopic techniques. The crystal structure of [CuL3·(py)]·py was investigated by single crystal X-ray structure analysis. The Cu(II) cation has near square pyramidal, penta-coordinate geometry. The binegatively charged tetradentate Schiff base is asymmetrically coordinated to the Cu(II) ion via the pyridine N atom, the azomethine N atom, the sulfonyl O atom and the deprotonated hydrazine N atom. There is a pyridine molecule apically coordinated to the Cu(II) ion. All the Schiff bases and their copper(II) complexes were screened by the disc diffusion method against multi-drug resistant (MDR) gram-negative and gram-positive bacteria. The minimum inhibitory concentration (MIC) values were also determined. These results show that the antibacterial activity of the Schiff bases against Methicillin-resistant Staphylococcus aureus (MRSA) is enhanced when they are chelated with the copper(II) ion. 相似文献
85.
Mohd Basyaruddin Abdul Rahman Naz Chaibakhsh Mahiran Basri Abu Bakar Salleh Raja Noor Zaliha Raja Abdul Rahman 《Applied biochemistry and biotechnology》2009,158(3):722-735
In this study, an artificial neural network (ANN) trained by backpropagation algorithm, Levenberg–Marquadart, was applied
to predict the yield of enzymatic synthesis of dioctyl adipate. Immobilized Candida antarctica lipase B was used as a biocatalyst for the reaction. Temperature, time, amount of enzyme, and substrate molar ratio were
the four input variables. After evaluating various ANN configurations, the best network was composed of seven hidden nodes
using a hyperbolic tangent sigmoid transfer function. The correlation coefficient (R
2) and mean absolute error (MAE) values between the actual and predicted responses were determined as 0.9998 and 0.0966 for
training set and 0.9241 and 1.9439 for validating dataset. A simulation test with a testing dataset showed that the MAE was
low and R
2 was close to 1. These results imply the good generalization of the developed model and its capability to predict the reaction
yield. Comparison of the performance of radial basis network with the developed models showed that radial basis function was
more accurate but its performance was poor when tested with unseen data. In further part of the study, the feedforward backpropagation
model was used for prediction of the ester yield within the given range of the main parameters. 相似文献
86.
Zafar A. Siddiqi M. Shahid Sarvendra Kumar Mohd Khalid Shabana Noor 《Journal of organometallic chemistry》2009,694(23):3768-301
Two novel dinuclear organotin(IV) complexes [n-Bu2Sn(imda)(H2O)]2·Bipy (1) and [n-Bu2Sn(imda)(H2O)]2·Phen (2) [H2imda = iminodiacetic acid, Bipy = 2,2′-bipyridine and Phen = 1,10-phenanthroline] were synthesised and characterized employing IR, 1H, 13C, 119Sn NMR, and 119Sn Mössbauer spectroscopic and elemental analyses. Single crystal X-ray crystallography of 1 has confirmed that it is a binuclear Sn(IV) species formed via carboxylate bridges where each metal adopted a seven coordinate distorted pentagonal bipyramidal geometry. The iminodiacetate dianion (imda2−) acts as a potential tridentate [N,O,O] carboxylate bridging ligand. The packing revealed that the additional α-diimine (Bipy or Phen) does not coordinate to metal ion. However, its presence in the crystal lattice as spacer helps for the formation of a supramolecular framework by bringing the two binuclear species close enough through extensive H-bonding. The in vitro cytotoxicity of compounds 1 and 2 indicate better results than cisplatin against three tumor cell lines investigated. 相似文献
87.
Yanuardi Raharjo Mohd Marsin Sanagi Wan Aini Wan Ibrahim Ahmedy Abu Naim Hassan Y. Aboul‐Enein 《Journal of separation science》2009,32(4):623-629
A liquid‐phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 μL) of isooctane as the acceptor phase was introduced continually to fill‐up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 μL) was first introduced into the hollow fiber and additional amounts (ca. 0.2 μL) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 μg/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples. 相似文献
88.
Mohd Rafein Zakaria Hidayah Ariffin Suraini Abd-Aziz Yoshihito Shirai 《Polymer Degradation and Stability》2010,95(8):1382-1386
Poly(3-hydroxybutyrate) [P(3HB)] homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymer was produced by Comamonas sp. EB172 using single and mixture of carbon sources. Poly(3-hydroxyvalerate) P(3HV) incorporation in the copolymer was obtained when propionic and valeric acid was used as precursors. Incorporation of 3HV fractions in the copolymer varied from 45 to 86 mol% when initial pH of the medium was regulated. In fed-batch cultivation, organic acids derived from anaerobically treated palm oil mill effluent (POME) were shown to be suitable carbon sources for polyhydroxyalkanoate (PHA) production by Comamonas sp. EB172. Number average molecular weight (Mn) produced by the strain was in the range of 153-412 kDa with polydispersity index (Mw/Mn) in the range of 2.2-2.6, respectively. Incorporation of higher 3HV units improved the thermal stability of P(3HB-co-3HV) copolymer. Thus the newly isolated bacterium Comamonas sp. EB172 is a suitable candidate for PHA production using POME as renewable and alternative cheap raw materials. 相似文献
89.
Zafar A. Siddiqi M. Shahid Mohd Khalid Shabana Noor Sarvendra Kumar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):61-68
The newly prepared homo-bimetallic complexes [M2(imda)2(H2O)4], [M2(imda)2(Bipy)2] (M = Co, Ni or Cu) and [Fe2(imda)2(H2O)3Cl] (H2imda = iminodiacetic acid and Bipy = 2,2′-bipyridine) have been studied employing IR, FAB-mass, 1H and 13C NMR, EPR and ligand field spectra, which indicated a high-spin state of metal ion with hexa-coordinate environment. 57Fe Mössbauer data of the homo-bimetallic complex [Fe2(imda)2(H2O)3Cl] confirm a high-spin configuration with Fe (±3/2 → 1/2) nuclear transitions and the presence of Kramer's double degeneracy. At RT, the spin–spin interactions of the neighbouring nuclei (Fe3+–Fe3+ = S5/2–S5/2) are anti-ferromagnetically coupled. However, at LNT, the complex acquires a mixed-valent [FeIII–FeII] composition corroborated from the X-band EPR data. CV studies indicated the presence of quasi-reversible redox CuII/I, CuII/III, FeIII/II, FeIII/I and FeII/I couples. 相似文献
90.
Mohd Marsin Sanagi Mazidatulakmam Miskam Wan Aini Wan Ibrahim Dadan Hermawan Hassan Y. Aboul‐Enein 《Journal of separation science》2010,33(14):2131-2139
A three‐phase hollow fiber liquid‐phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1‐octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 μL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H3PO4, pH 3.0; organic solvent, 1‐octanol; acceptor solution, 40 μL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05–0.30 mg/L with r2>0.9900 and LODs were in the range of 0.01–0.04 mg/L with RSDs of 1.25–2.32%. Excellent enrichment factors of up to 398‐folds were obtained. It was found that the partition coefficient (Ka/d) values were high for 2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol and 2,6‐dinitrophenol and that the individual partition coefficients (Korg/d and Ka/org) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples. 相似文献