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  1. Variations des caractéristiques des huiles de palme et notamment de leurs caroténoides
    Bienaymé A, Servant M
    Qualitas Plantarum et Materiae Vegetabiles, 1958;3-4:336-353.
    DOI: 10.1007/BF01884062
    During two years the authors have assembled monthly analytical data of oilpalms, from 15 different stations. The determinations spread as far as the French, Portuguese and Spanish territory in Africa and British Malaya also. The following analyses were carried out: iodine number, titer point, melting point and the carotenoids of these oils, according to origine, race and time of gathering. As to iodine number and amount of carotenoid, the race is decisive for these data; the oils from the natural stock of the Ivory Coast have a higher iodine number (57-60). The oils from the natural stock of Togo, Dahomey, Portuguese and French Guinea are richer in carotene (up to 0.16, even 0.19%) with medium iodine number (54-56). The oils from the industrial plantations, with selected trees of the race Dura-Deli, from the Far East as well as from the Ivory Coast, have lower iodine numbers (52-53) and are poor in carotene (0.05). South of the equator in Africa, all analysed races of oil palms had a lower iodine number (53-55) and were poor in carotene (0.05). During one year the amount of carotene fluctuates about one third of its maximum; this maximum is rather striking in Togo and Dahomey; it is to be found from January to May; period of high production of the oil in the Palm groves, e.g. in the dry season with warm climate and good insolation. Heavy rain-showers effect a rapid decrease of the contents of carotene after six weeks (duration of the formation of the fruit). Furthermore, the residual oils (extracted by solvents) were analysed; they are 2 to 3 times richer in carotenoids than the common palm oil; but the contents of β-carotene seems somewhat lower. The authors think it possible to find exactly defined uses for the different oils. © 1958 Uitgeverij Dr. W. Junk.
    Matched MeSH terms: Solvents
  2. Chloroquine polymeric membrane electrodes: Development and applications
    Saad B, Kanapathy K, Ahmad MN, Hussin AH, Ismail Z
    Talanta, 1991 Dec;38(12):1399-402.
    PMID: 18965315
    Three main types of PVC solvent polymeric membrane ion-selective electrodes for chloroquine are described. They are based on three ion-pairing agents namely dipicrylamine (DPA), tetraphenylborate (TPB) or tetrakis(4-chlorophenyl)borate (TCPB) with either dioctylphenyl phosphonate (DOPP) or trioctyl phosphate (TOP) solvent mediator. All electrodes exhibit Nernstian responses, fast dynamic response times and a wide useful pH range. The best all-round electrode is based on TPB and TOP plasticizing solvent mediators with a limit of detection of 7.1 x 10(-6)M and was utilized for the assay of chloroquine in tablets. Direct potentiometric determinations with either the analyte addition method or the normal calibration method gave results comparable to the official method.
    Matched MeSH terms: Solvents
  3. Comparison of solvent extraction and solid-phase extraction for the determination of organochlorine pesticide residues in water
    Tan GH
    Analyst, 1992 Jul;117(7):1129-32.
    PMID: 1524230
    Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.
    Matched MeSH terms: Solvents
  4. A Novel Optical Complex between an Organic Substrate and a Polyoxometalate. Crystal and Molecular Structure of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O (HMPA = Hexamethylphosphoramide)
    Niu Jy Jy, You Xz Xz, Duan Cy Cy, Fun Hk Hk, Zhou Zy Zy
    Inorg Chem, 1996 Jul 03;35(14):4211-4217.
    PMID: 11666630
    A solvated complex of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O composed the heteropolytungstate alpha-H(4)SiW(12)O(40) and the organic substrate hexamethylphosphoramide (HMPA) has been synthesised, purified, and characterized. The electronic spectra (lambda = 220-500 nm) as well as the (1)H NMR spectra for the title compound dissolved in CD(3)CN establish that this complex dissociates into free SiW(12)O(40)(4)(-) and HMPA moieties in solution unless the organic substrate HMPA is present in very high concentrations. The solid reflectance electronic spectra and IR spectra indicate that there is interaction between the alpha-H(4)SiW(12)O(40) and the organic substrate. The complex has no photosensitivity under irradiation of sunlight, but under the near-UV light result in a charge transfer by oxidation of the HMPA and the reduction of the polyoxometalate. Light yellow polyhedrons of the title compound crystallize from the aqueous solvent of acetonitrile and aqueous solution as the formula of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O in the monoclinic, space group P2(1). The unit cell has a = 12.791(3) Å, b = 22.103(6) Å, c = 15.532(4) Å, beta = 102.860(10) degrees, and Z = 2. From the bond-valence parameters, it was found that the four hydrogen atoms of the polyoxometalate were combined with the N atoms of the four HMPA respectively. The title compound shows a certain second-order and third-order nonlinear optical response of I(2)(omega) = 0.7I(2)(omega)(KDP) and chi((3)) = 2.63 x 10(-)(11) esu, respectively.
    Matched MeSH terms: Solvents
  5. The effect of water activity on modified lipase during esterification
    Salleh AB, Taib M, Basri M, Ampon K, Yunus WM, Razak CN
    Ann N Y Acad Sci, 1996 Oct 12;799:328-31.
    PMID: 8958097
    Matched MeSH terms: Solvents
  6. Tributyltin distribution in the coastal environment of Peninsular Malaysia
    Tong SL, Pang FY, Phang SM, Lai HC
    Environ Pollut, 1996;91(2):209-16.
    PMID: 15091442
    The occurrence of tributyltin (TBT) is reported in the coastal waters of a few selected sites in Peninsular Malaysia. Water, bivalves and sediment samples collected were analysed specifically for TBT using sensitive analytical methods which involved a solvent extraction procedure with appropriate clean-up followed by graphite furnace atomic absorption spectrometric measurements. The levels of TBT in the seawater in unexposed areas were found in the range from <3.4 to 20 ng litre(-1) as compared to coastal areas with high boat and ship activities where TBT levels in seawater were generally above 30 ng litre(-1), with the highest level found at 281.8 ng litre(-1). TBT levels in the tissues of random cockle and soft-shell clam samples from local markets were found in the range from <0.5 to 3.7 ng g(-1) wet weight. The levels of TBT found in green mussel samples both from the market (23.5 ng g(-1) wet weight) and those from a mussel farm (14.2 ng g(-1) wet weight) indicate slight accumulation of TBT. In sediments, TBT levels were found ranging from <0.7 ng g(-1) dry weight in unexposed coastal sites to as high as 216.5 ng g(-1) dry weight for a site within a port area.
    Matched MeSH terms: Solvents
  7. Penentuan Isotop Uranium dan Torium dalam Monazit, Xenotim dan Zirkon Menggunakan Spektrometri Alfa
    Amran B. Ab. Majid, Mohd Zahari Abdullah, Zaharuddin Ahmad
    Sains Malaysiana, 1996;25.
    The determination technique for U (238U, 235U, 234U) and Th (232Th, 230Th, 228Th) isotopes using alpha spectrometry was developed. The developed technique involved digestion, dissolution, coprecipitation, solvent extraction and electrodeposition methods. The NBS River Sediment and Rocky Flats Soil Standard Reference Materials were analysed to determine the accuracy of the technique. A good accuracy and high percentage recovery of the carrier (70 - 90%) indicated that the developed technique was suitable for U and Th isotopes determination. The technique was used to determine the U and Th concentration in monazite, xenotime and zircon samples. The results showed that the U and Th total concentrations were in the range of 21.03 to 171.25 Bq/g and 27.48 to 242.87 Bq/g respectively.
    Kaedah penguraian, pemelarutan, pemendakan bersama, ekstraksi pelarut dan pemendapan elektrik telah dikaji dan digunakan untuk mendapatkan suatu teknik yang terbaik dalam penentuan isotop uranium 234U, 235U & 238U) dan torium 228Th, 230Th & 232Th) menggunakan sistem spektrometri alfa. Kepekatan isotop U dan Th dalam bahan rujukan piawai River Sediment dan Rocky Flats Soil (NBS) telah dianalisis untuk menentukan kejituan teknik yang dibangunkan. Kajian ini mendapati kepekatan isotop yang diperolehi adalah menghampiri nilai teraku (sijil) dan peratus perolehan semula pembawa yang besar (70-90%). Ini menunjukkan teknik yang dibangunkan sesuai digunakan untuk penentuan isotop uranium dan torium. Seterusnya teknik yang dibangunkan telah digunakan untuk menentukan kandungan uranium dan torium dalam sampel monazit, xenotim dan zirkon tempatan. Kepekatan jumlah isotop uranium yang diperolehi didapati berada dalam julat 21.03 - 171.25 Bq/g manakala kepekatan jumlah isotop torium pula terletak antara 27.48 - 242.87 Bq/g.
    Matched MeSH terms: Solvents
  8. Antimalarial activity of extracts of Malaysian medicinal plants
    Najib Nik A Rahman N, Furuta T, Kojima S, Takane K, Ali Mohd M
    J Ethnopharmacol, 1999 Mar;64(3):249-54.
    PMID: 10363840
    In vitro and in vivo studies revealed that Malaysian medicinal plants, Piper sarmentosum, Andrographis paniculata and Tinospora crispa produced considerable antimalarial effects. Chloroform extract in vitro did show better effect than the methanol extract. The chloroform extract showed complete parasite growth inhibition as low as 0.05 mg/ml drug dose within 24 h incubation period (Andrographis paniculata) as compared to methanol extract of drug dose of 2.5 mg/ml but under incubation time of 48 h of the same plant spesies. In vivo activity of Andrographis paniculata also demonstrated higher antimalarial effect than other two plant species.
    Matched MeSH terms: Solvents
  9. Lipase immobilized on poly(VP-co-HEMA) hydrogel for esterification reaction
    Basri M, Samsudin S, Ahmad MB, Razak CN, Salleh AB
    Appl Biochem Biotechnol, 1999 Sep;81(3):205-17.
    PMID: 15304777
    Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl- 2-pyrrolidone-co-2-hydroxyethyl methacrylate) (poly[VP-co-HEMA]) hydrogel, and divinylbenzene was the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases was also determined. Increasing the percentage of composition of VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized on VP(%):HEMA(%) 90:10 exhibited the highest activity. Lipase immobilized on VP(%):HEMA(%) 50:50 showed the highest thermal, solvent, storage, and operational stability compared to lipase immobilized on other compositions of hydrogels as well as the native lipase.
    Matched MeSH terms: Solvents
  10. Fatty acid compositions in local sea cucumber, Stichopus chloronotus, for wound healing
    Fredalina BD, Ridzwan BH, Abidin AA, Kaswandi MA, Zaiton H, Zali I, et al.
    Gen. Pharmacol., 1999 Oct;33(4):337-40.
    PMID: 10523072
    Fatty acid profile from crude extracts of local sea cucumber Stichopus chloronotus was determined using gas chromatography (GC) technique. The extracts were prepared separately in methanol, ethanol, phosphate buffer saline (PBS), and distilled water as part of our study to look at the affinity of these solvents in extracting the lipid from sea cucumber. The PBS and distilled water extractions indicate water-soluble components, while the organic fractions are extracted in methanol and ethanol as organic solvents. Furthermore, water extraction is the conventional method practiced in Malaysia. In our analysis the C14:0 (myristic), C16:0 (palmitic), C18:0 (stearic), C18:2 (linoleic), C20:0 (arachidic), and C20:5 (eicosapentaenoic, EPA) were significantly different (p < 0.01) in the four solvent extractions. However, the PBS extraction contained a much higher percentage of EPA (25.69%) compared to 18.89% in ethanol, 7.84% in distilled water, and only 5.83% in methanol, and variances were significantly different (p < 0.01 ). On the other hand, C22:6 (docosahexaenoic acid or DHA) is much higher in water extraction (57.55%), in comparison to the others where only 3.63% in PBS and 1.20% in methanol, and this difference is significant at p < 0.01. No DHA was detected in ethanol extractions. Subsequently, C18:1 (oleic acid) was only detected in PBS (21.98%) and water extraction (7.50%). It is interesting that palmitic acid, C16:() was higher in methanol (20.82%) and ethanol (2.18%), while 12.55% was detected in PBS and only 2.20% in water extraction: and again this was significantly different at p < 0.01. Although our results have shown that all four solvents were different in terms of their ability to extract fatty acids, the major component for tissue repair was well preserved. Probably this is one of the important precocious steps when working with a delicate sea cucumber, in both experimental and/or at the preparative stages. Freshness of the sea cucumber samples is important when undertaking this type of experiment. Finally, we believe that the local sea cucumber S. chloronotus contains all the fatty acids required to play a potential active role in tissue repair.
    Matched MeSH terms: Solvents
  11. Tris(8-quinolinolato-N,O)cobalt(III) ethanol solvate
    Shanmuga Sundara Raj S, Razak IA, Fun HK, Zhao PS, Jian F, Yang X, et al.
    Acta Crystallogr C, 2000 Apr 15;56(Pt 4):E130-1.
    PMID: 15263175
    In the crystal of the title complex, [Co(C(9)H(6)NO)(3)].C(2)H(5)OH, the central Co atom has a distorted octahedral coordination comprised of three N atoms and three O atoms from the three 8-quinolinolato ligands. The three Co-O bond distances are in the range 1.887 (2)-1.910 (2) A, while the three Co-N bond distances range from 1.919 (2) to 1.934 (2) A. The solvent ethanol molecule forms an intermolecular O-H.O hydrogen bonding with a quinolinolato ligand.
    Matched MeSH terms: Solvents
  12. Fulltext The Effects Of Alcohol-free 0.12% W/N Chlorhexidine Gluconate Mouthrinse On Oral Health
    Uma, S., Swaminathan, D.
    Ann Dent, 2001;8(1):-.
    MyJurnal
    CWorhexidine gluconate, a dicationic bisbiguanide agent, contains anti-plaque properties. Most chlorhexidine gluconate mouth rinses presently available contain alcohol in varying concentrations. The role of alcohol in these mouth rinses is to act as a preservative and solvent although it may have deleterious effects on the oral epithelium on long term usage. Recently, an alcohol-free 0.12 % w/v chlorhexidine gluconate mouth rinse (Oradex®) has become available in Malaysia. This clinical study is aimed at determining the effects of this alcohol-free product compared to a placebo. A group of 60 meticulously screened subjects were assigned into two groups of 30 each. The first group started using the test product for 2 weeks followed by a washout period of 4 weeks. After this duration, this group used the placebo for a further 2 weeks. The 2nd group underwent similar protocol as the 1st except that this group started with the placebo. Measurements consisting of the following scores were recorded at baseline and after 2 weeks for each group: Plaque, Gingivitis: Papillary Bleeding, Stain and Calculus. Full mouth prophylaxis was carried out for all subjects after measurements at baseline as well as after the 2-week period. They were told to rinse with 15 ml of the designated mouth rinse twice daily for thirty seconds each after tooth brushing. The results of this study indicated that there was significant improvement in the plaque, gingival and papilla bleeding scores compared to the placebo. Stain and calculus scores were significantly increased for the test product when compared to the placebo. In conclusion, this study showed that alcohol-free 0.12 % w/v chlorhexidine gluconate mouth rinse is effective in reducing plaque and gingivitis but causes staining and calculus formation.
    Matched MeSH terms: Solvents
  13. Anaerobic fermentation of gelatinized sago starch-derived sugars to acetone-1-butanol-ethanol solvent by Clostridium acetobutylicum
    Madihah MS, Ariff AB, Khalil MS, Suraini AA, Karim MI
    Folia Microbiol (Praha), 2001;46(3):197-204.
    PMID: 11702403
    A study of the kinetics and performance of solvent-yielding batch fermentation of individual sugars and their mixture derived from enzymic hydrolysis of sago starch by Clostridium acetobutylicum showed that the use of 30 g/L gelatinized sago starch as the sole carbon source produced 11.2 g/L total solvent, i.e. 1.5-2 times more than with pure maltose or glucose used as carbon sources. Enzymic pretreatment of gelatinized sago starch yielding maltose and glucose hydrolyzates prior to the fermentation did not improve solvent production as compared to direct fermentation of gelatinized sago starch. The solvent yield of direct gelatinized sago starch fermentation depended on the activity and stability of amylolytic enzymes produced during the fermentation. The pH optima for alpha-amylase and glucoamylase were found to be at 5.3 and 4.0-4.4, respectively. alpha-Amylase showed a broad pH stability profile, retaining more than 80% of its maximum activity at pH 3.0-8.0 after a 1-d incubation at 37 degrees C. Since C. acetobutylicum alpha-amylase has a high activity and stability at low pH, this strain can potentially be employed in a one-step direct solvent-yielding fermentation of sago starch. However, the C. acetobutylicum glucoamylase was only stable at pH 4-5, maintaining more than 90% of its maximum activity after a 1-d incubation at 37 degrees C.
    Matched MeSH terms: Solvents/metabolism
  14. NETASA: neural network based prediction of solvent accessibility
    Ahmad S, Gromiha MM
    Bioinformatics, 2002 Jun;18(6):819-24.
    PMID: 12075017
    MOTIVATION: Prediction of the tertiary structure of a protein from its amino acid sequence is one of the most important problems in molecular biology. The successful prediction of solvent accessibility will be very helpful to achieve this goal. In the present work, we have implemented a server, NETASA for predicting solvent accessibility of amino acids using our newly optimized neural network algorithm. Several new features in the neural network architecture and training method have been introduced, and the network learns faster to provide accuracy values, which are comparable or better than other methods of ASA prediction.

    RESULTS: Prediction in two and three state classification systems with several thresholds are provided. Our prediction method achieved the accuracy level upto 90% for training and 88% for test data sets. Three state prediction results provide a maximum 65% accuracy for training and 63% for the test data. Applicability of neural networks for ASA prediction has been confirmed with a larger data set and wider range of state thresholds. Salient differences between a linear and exponential network for ASA prediction have been analysed.

    AVAILABILITY: Online predictions are freely available at: http://www.netasa.org. Linux ix86 binaries of the program written for this work may be obtained by email from the corresponding author.

    Matched MeSH terms: Solvents
  15. Modified enzymes for reactions in organic solvents
    Salleh AB, Basri M, Taib M, Jasmani H, Rahman RN, Rahman MB, et al.
    Appl Biochem Biotechnol, 2002 10 25;102-103(1-6):349-57.
    PMID: 12396136
    Recent studies on biocatalysis in water-organic solvent biphasic systems have shown that many enzymes retain their catalytic activities in the presence of high concentrations of organic solvents. However, not all enzymes are organic solvent tolerant, and most have limited and selective tolerance to particular organic solvents. Protein modification or protein tailoring is an approach to alter the characteristics of enzymes, including solubility in organic solvents. Particular amino acids may play pivotal roles in the catalytic ability of the protein. Attaching soluble modifiers to the protein molecule may alter its conformation and the overall polarity of the molecule. Enzymes, in particular lipases, have been chemically modified by attachment of aldehydes, polyethylene glycols, and imidoesters. These modifications alter the hydrophobicity and conformation of the enzymes, resulting in changes in the microenvironment of the enzymes. By these modifications, newly acquired properties such as enhancement of activity and stability and changes in specificity and solubility in organic solvents are obtained. Modified lipases were found to be more active and stable in organic solvents. The optimum water activity (a(w)) for reaction was also shifted by using modified enzymes. Changes in enantioselective behavior were also observed.
    Matched MeSH terms: Solvents
  16. Effect of Eurycoma longifolia Jack on libido in middle-aged male rats
    Ang HH, Lee KL
    J Basic Clin Physiol Pharmacol, 2002;13(3):249-54.
    PMID: 12670032 DOI: 10.1515/jbcpp.2002.13.3.249
    The effect of increasing doses of various fractions of Eurycoma longifolia Jack extracts on libido was examined in middle-aged male rats. The results showed that a high dose (800 mg/kg) of all E. longifolia Jack extracts significantly increased mount frequency (MF) (P < 0.05) over that of untreated controls, but had no effect on the frequency of intromission or ejaculation. Methanol, chloroform, water, and butanol fractions exhibited MF of 2.5 +/- 0.1, 2.6 +/- 0.3, 2.5 +/- 0.1 and 2.6 +/- 0.2, respectively, in adult, middle-aged male rats, and retired breeders versus 2.3 +/- 0.1 in untreated controls. This translated to a minor increase in MF of 8.7%, 13.0%, 8.7%, and 13.0% for these fractions, respectively, during the 20-minute observation period. The results of this study show that E. longifolia Jack extracts can increase libido in middle-aged male rats.
    Matched MeSH terms: Solvents
  17. Kinetics and mechanism of intramolecular carboxylic acid participation in the hydrolysis of N-methoxyphthalamic acid
    Khan MN, Ariffin A
    Org Biomol Chem, 2003 Apr 21;1(8):1404-8.
    PMID: 12929671
    The rate of formation and disappearance of phthalic anhydride (PAn) intermediate in the aqueous cleavage of N-methoxyphthalamic acid (NMPA) under acidic pH was studied spectrophotometrically in mixed CH3CN-H2O solvents. The rate of formation of PAn from NMPA is almost independent of the change in acetonitrile content from 20 to 70% v/v in mixed aqueous solvents. The rate constants for the formation of PAn from NMPA are approximately 10-fold smaller than the corresponding rate constants for the formation of PAn from o-carboxybenzohydroxamic acid (OCBA). These observations are ascribed to the consequence of the occurrence of slightly different mechanisms in these reactions.
    Matched MeSH terms: Solvents
  18. Analysis of selected pesticides and alkylphenols in human cord blood by gas chromatograph-mass spectrometer
    Tan BL, Ali Mohd M
    Talanta, 2003 Nov 4;61(3):385-91.
    PMID: 18969198 DOI: 10.1016/S0039-9140(03)00281-9
    A total of seven pesticides and eight alkylphenols were monitored using this method for the determination of their trace levels in human cord blood. The pesticides are lindane, diazinon, alpha-endosulfan, beta-endosulfan, endosulfan sulfate, chlorpyrifos and endrin; while the alkylphenols are 4-n-butylphenol, 4-n-pentylphenol, 4-n-hexylphenol, 4-t-octylphenol, 4-n-heptylphenol, nonylphenol, 4-n-octylphenol and bisphenol A. The pesticides and alkylphenols in the cord blood samples were extracted with solid phase extraction IST C18 cartridges and analyzed by selected ion monitoring mode using quadrapole detector in Shimadzu QP-5000 gas chromatograph-mass spectrometer. Trace levels of pesticide and alkylphenols in the range of non-detectable to 15.17 ng ml(-1), were detected in the human cord blood samples. This technique of monitoring the levels of endocrine-disruptors in blood samples is consistent, reliable and cost effective while reducing wastage of time and solvents.
    Matched MeSH terms: Solvents
  19. Optimization of the enzyme-catalyzed synthesis of amino acid-based surfactants from palm oil fractions
    Soo EL, Salleh AB, Basri M, Zaliha Raja Abdul Rahman RN, Kamaruddin K
    J Biosci Bioeng, 2003;95(4):361-7.
    PMID: 16233420
    The feasibility of using palm oil fractions as cheap and abundant sources of raw material for the synthesis of amino acid surfactants was investigated. Of a number of enzymes screened, the best results were obtained with the immobilized enzyme, Lipozyme. The effects of temperature, solvent, incubation period, fatty substrate/amino acid molar ratio, enzyme amount, and water removal on the reactions were analyzed and compared to those on reactions with free fatty acids and pure triglycerides as fatty substrates. All reactions were most efficient when carried out at high temperatures (70-80 degrees C) in hexane as a solvent. However, while reactions with free fatty acids proceeded better when a slight excess of the free fatty acids over the amino acids was used, reactions with triglycerides and palm oil fractions were best performed at equimolar ratios. Also, the addition of molecular sieves slightly enhanced reactions with free fatty acids but adversely affected reactions with triglycerides and palm oil fractions. Although reactions with palm oil fractions took longer (6 d) to reach equilibrium compared to reactions with free fatty acids (4 d) and pure triglycerides (4 d), better yields were obtained. Such lipase-catalyzed transacylation of palm oil fractions with amino acids is potentially useful in the production of mixed medium- to long-chain surfactants for specific applications.
    Matched MeSH terms: Solvents
  20. Fluorescence studies of selected 2-alkylaminopyrimidines
    Abdullah Z, Tahir NM, Abas MR, Aiyub Z, Low BK
    Molecules, 2004 Jun 30;9(7):520-6.
    PMID: 18007451
    The reactions of 2-chloropyrimidine with methylamine, ethylamine and piperidine gave the corresponding 2-N-methylamino-, 2-N-ethylamino- and 2N- piperidinopyrimidines, respectively. The fluorescence properties of these alkylamino derivatives in chloroform, ethyl acetate, carbon tetrachloride, acetone, ether, ethanol and methanol were studied. All the alkylamino derivatives showed the highest fluorescence intensity in polar protic solvents; thus 2-N-methylaminopyrimidine (highest fluorescence intensity at 377 nm when excited at 282 nm) and 2-N-ethylaminopyrimidine (highest fluorescence intensity at 375 nm, when excited at 286 nm) showed the highest fluorescence in methanol. In ethanol, 2-N-piperidinopyrimidine showed a fluorescence peak at 403 nm when excited at 360 nm and in chloroform it fluoresced at 392 nm when excited at 356 nm.
    Matched MeSH terms: Solvents/chemistry
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