Nmr

Most spectroscopic studies of the reaction products formed by ninhydrin, 1,2-indanedionezinc (Ind-Zn) and 1,8-diazafluoren-9-one (DFO) when reacted with amino acids or latent fingermarks on paper substrates are focused on visible absorption or luminescence spectroscopy. In addition, structural elucidation studies are typically limited to solution-based mass spectrometry or liquid nuclear magnetic resonance (NMR) spectroscopy, which does not provide an accurate representation of the fingermark development process on common paper substrates. The research presented in this article demonstrates that solid-state carbon-13 magic angle spinning NMR ( 13 C-MAS-NMR) is a technique that can not only be utilised for structural studies of fingermark enhancement reagents, but is a promising technique for characterising the effect of paper chemistry on fingermark deposition and enhancement. The latter opens up a research area that has been under-explored to date but has the potential to improve our understanding of how fingermark secretions and enhancement reagents interact with paper substrates.

The differential Biot-Savart law of classical electrodynamics was applied to develop a ring current model for the magnetic shielding of the carbon nucleus in benzene. It is shown that the local effect of the p currents, induced by a magnetic field normal to the molecular plane, on the s C k out-of-plane shielding tensor component vanishes. However, approximately 10% of s C k is due to the shielding contributions from p current density in the region of the other carbon atoms. Magnetic shielding density maps obtained via quantum mechanical procedures confirm the predictions of the classical model.

The cysteine-rich N-terminal domain of the micronemal adhesive protein MIC1 (MIC1-NT) from Toxoplasma gondii was cloned, expressed in Escherichia coli and purified. MIC1-NT is amenable to structural studies as shown by preliminary NMR and X-ray analysis. Positive results with two further micronemal proteins indicate that our strategy has wider application.

The pharmacokinetics, biodistribution and the metabolic pathway of roscovitine were investigated in Sprague-Dawley rats after a single intravenous dose of 25 mg/kg. Blood, lungs, kidney, liver, testis, adipose tissue, spleen and brain were removed at different time-points. Plasma and tissue samples were analyzed using high performance liquid chromatography. The metabolites were identified using liquid chromatography/tandem mass spectrometry and nuclear magnetic resonance spectroscopy.

Dielectric permittivity (ε) and temperature effects on indirect spin–spin coupling constants were studied using acetonitrile as a probe molecule. Experiments were accompanied by hybrid DFT (density functional theory) studies, where the solvent was modeled using the polarization continuum model. Owing to its numerous types of J-couplings, acetonitrile is a very convenient molecule against which various basis sets can be tested or the best basis set can be selected for a given study. The results show reasonable agreement between calculated and experimental values. According to our data, scalar spin–spin coupling constants undergo substantial shifts at lower values of the dielectric constant. Thus J-coupling values are not transferable between measurements made at differing ε–conditions, and the assumption of the ε-independence of the J-coupling can lead to crucial mistakes in experiments using low-ε media. Dielectric permittivity also causes small geometric fluctuations within the molecule, which themselves can affect J-coupling values. Examinations of the results computed with frozen and relaxed geometries show that geometry mediation mostly affects the spin-dipole term of the J-coupling; hence, for accurate evaluation of the latter, frozen geometries are not acceptable. Another interesting fact revealed is the connection between the solvent dielectric properties and the temperature-dependence slopes of J-couplings in corresponding media. Copyright © 2008 John Wiley & Sons, Ltd.

The effects of g irradiation on polymers used in food packaging have been studied by NMR. In order to assess the presence of a threshold dose for an observable effect, the whole range of 1-100 kGy was investigated. Polystyrene, poly-butadiene, styrene-acrylonitrile, highimpact polystyrene and acrylonitrile-butadiene-styrene were studied before and after the g irradiation treatment and in the presence or in the absence of antioxidants and stabilizers. In the absence of stabilizers, the effect of g irradiation on polystyrene is negligible even when operating at high doses. In contrast, the role of antioxidants and stabilizers is crucial in poly-butadiene and butadiene-containing copolymers. High-resolution NMR, dynamic mechanical analysis, impact analysis and gel permeation chromatography performed on irradiated polystyrene samples do not show any detectable effect, confirming polystyrene as an ideal polymer for food packaging use.

Protein splicing elements, termed inteins, provide a fertile source for innovative biotechnology tools. First harnessed for protein purification, inteins are now used to express cytotoxic proteins, to segmentally modify or label proteins, to cyclize proteins or peptides, to study structure-activity relationships and to generate reactive polypeptide termini in expressed proteins for an expanding list of chemoselective reactions, including protein ligation.

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The structure of mitragynaline, an indole alkaloid isolated from Malaysian Mitragyna speciosa, was revised as formula 3 by analysis of the NMR spectra measured at low temperature and by chemical transformation with DDQ oxidation from the known alkaloid mitragynine (5).

A novel nickel-based complex coordinated with an asymmetric diphosphinoamine ligand was synthesized and fully characterized. Single crystals of good quality were also obtained, and the solid-state structure of the complex was studied via X-rays diffraction. The catalytic activity of this Ni(II) complex in the vinyl-type polymerization of norbornene was studied with methylaluminoxane (MAO) as the cocatalyst/activator. The influence of the reaction time, the equivalents of MAO used, and the concentration of the monomer on: (i) the activity of the catalytic system; (ii) the isolated yield of the polymer; and (iii) the molecular weight and molecular weight distribution of the polymer were investigated. The isolated polynorbornene (PNB) yields are significantly higher compared with those reported for other similar nickelbased systems. The as-obtained PNBs are characterized by high molecular weights and relatively narrow and monomodal molecular weight distributions (amongst the narrowest reported in the literature). The linear dependence of the molecular weight of the obtained PNB on the concentration of norbornene points toward a controlled polymerization reaction.

Biodiesel fuel has shown great promise as an alternative to petro-diesel fuel. Biodiesel production is widely conducted through transesterification reaction, catalyzed by homogeneous catalysts or heterogeneous catalysts. Fourteen new organotin(IV) carboxylate complexes were preliminary screened for their catalytic activity in transesterification. The transesterification reaction, which is a major path to produce biodiesel, occurs between the triglyceride vegetable oils with alcohols to form esters (biodiesel) and glycerol. The present investigation involves the production of environmental-friendly heterogeneous catalyst, organotin(IV) carboxylates, for biodiesel production from corn oil. 83% Conversion of corn oil into biodiesel was obtained in the presence of the synthesized catalysts. Therefore, the newly synthesized organotin(IV) carboxylate complexes can be used as one of the best catalysts in future for the biodiesel synthesis.

We investigated the effects of the degradation of natural rubber in a test piece of artwork as well as in test samples that have been exposed to accelerated degradation by UV irradiation. Two types of nuclear magnetic resonance (NMR) have been applied. Unilateral 1 H NMR is non-invasive and is applied directly to an artwork. It allows for spatial resolution in the form of depth profiles to be obtained. The results were compared to solid state 1 H and 13 C NMR, which requires sampling, but yields more detailed chemical information due to its spectroscopic resolution. Both techniques allow for the detection of changes in natural rubber due to degradation. 13 C NMR spectroscopy reflects the differences in the chemical process of degradation caused by short, intense, irradiation compared to long-term oxidative degradation. 1 H NMR spectroscopy assesses to what extent the hydrogen sites in a sample contribute to the T 2 decays measured by unilateral NMR. The signal from very rigid parts of the sample decays too fast to be detected by this method.

Natural starches obtained by fruit seeds have been a subject of studies because of their applications, as a consequence of their chemical properties. As it is known, the fruits depend on the geographic region. Because of this, several factors affect the seed starches nature, such as granules size, morphology, components, and composition. Thus, to better understand starch properties, it is necessary to investigate the chemical behavior of these factors. This work focused on the chemical components and molecular dynamic behavior of the Dipterxy Alata Vogel (cumbaru) starch, because this fruit is very popular and is used in abundance for people because they think that it is good for some kinds of diseases. The main chemical components and the molecular dynamics of starch from the Dipterxy Alata Vogel were studied by applying solid-state 13C nuclear magnetic resonance spectroscopy (NMR). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2151–2154, 2004

Haloperidol (Hal), a highly hydrophobic drug, was complexed with two i-cyclodextrin (i-CD) derivatives. Hal solubility was increased 20-fold in the presence of a 10-fold excess of methyl i-CD (Mei-CD) and 12-fold in the presence of a 10-fold excess of 2-hydroxypropyl i-CD (HPi-CD). The stoichiometries and stability constants of Hal-Mei-CD (1:1 and 2345 M − 1 at 27°C) and Hal -HPi-CD (1:1 and 2112 M − 1 at 27°C) complexes were calculated by the continuous variation and phase solubility methods respectively. Differential scanning calorimetry and 1 H-NMR were used to confirm the formation of inclusion complexes. Moreover, the enthalpy and entropy of the complexation process were calculated for both complexes in order to obtain such information as the main 'driving force' and whether or not complex formation is thermodynamically favoured. This was achieved by monitoring the isothermic solubility lines at various temperatures. © 1997 Elsevier Science B.V.

The chemokine receptor CCR5 serves as a co-receptor for the Human Immunodefficiency Virus type-1, HIV-1. The CCR5 N-terminal segment, the second extracellular loop (ECL2) and the transmembrane helices have been implicated in binding the envelope glycoprotein gp120. Peptides corresponding to the sequence of the putative ECL2 as well as peptides containing the ECL1 and ECL3 were found to inhibit HIV-1 infection. The aromatic residues in the C-terminal half of an ECL2 peptide were shown to interact with gp120. In the present study we determined that in aqueous buffer the segment Q188-Q194 in an elongated ECL2 peptide (R168 to K197) forms an amphiphilic helix, which corresponds to the beginning of the fifth transmembrane helix in the crystal structure of CCR5. Two dimensional Saturation Transfer Difference NMR spectroscopy and dynamic filtering studies revealed the involvement of Y187, F189, W190 and F193 of the helical segment, in the interaction with gp120. The crystal structure of CCR5 shows that the aromatic side chains of F189, W190 and F193 point away from the binding pocket and interact with the membrane or with an adjacent CCR5 molecule and therefore, could not interact with gp120 in the intact CCR5 receptor. We conclude that these three aromatic residues of ECL2 peptides interact with gp120 through hydrophobic interactions not representative of the interactions of the intact CCR5 receptor. The HIV-1 inhibition by ECL2 peptides as well as by ECL1 and ECL3 peptides and peptides corresponding to ECL2 of CXCR4, which serves as an alternative HIV-1 co-receptor, suggests that there is a hydrophobic surface in the envelope spike that could be a target for HIV-1 entry inhibitors.

The 1 H and 13 C NMR spectra of the new calix[4]arene-based tetraketone were completely assigned by oneand two-dimensional homo-and heteronuclear experiments (1 H-1 H COSY, 1 H-13 C HMQC, and HMBC) at 400 and 100 MHz, respectively, at 25 • C standard pulse sequence. 1 H and 13 C spectra were measured at room temperature for 25,26,27,28-tetramethylcalix[4]arene tetraketone (1). 13 C{ 1 H}, DEPT and NMR techniques were used to distinguish the methyl, methylene and methine carbon resonance signals of calix[4]arene 1. Correlation of 1D (1 H, 13 C{ 1 H}, DEPT) and 2D (HMQC and HMBC) NMR data was used to completely assign various overlapping and broad signals of calix[4]arene 1. Heteronuclear multibond correlation (HMBC) studies were used to completely assign various carbon resonances. Our results show that the conformation of calix[4]arene 1 in the solution is very similar to the cone conformation reported in the literature.

The reaction of h,-bis(organodichlorostannyl)alkanes [R(Cl 2 )SnCH 2 ] 2 Z with their corresponding organotin oxides [R(O)SnCH 2 ] 2 Z or (t-Bu 2 SnO) 3 provides the new spacer-bridged tetraorganodistannoxanes {[R(Cl)SnCH 2 ] 2 Z]O} n (22, Z= CH 2 , R= Me 3 SiCH 2 ; 23, Z=CH 2 , R=Me 3 CCH 2 ; 24, Z=CH 2 CH 2 , R=Me 3 SiCH 2 ; 25, Z= CH 2 CH 2 , R=Me 3 CCH 2 ; 26, Z= CH 2 CH 2 , R=Me 2 CHCH 2 ; 27, Z=Me 2 Si, R =Me 3 SiCH 2 ). The acetate substituted derivative 28 {[R(AcO)SnCH 2 ] 2 CH 2 ]O} n (R= Me 3 SiCH 2 ) is obtained by reaction of 22 with silver acetate or by treatment of the organotin oxide [R(O)SnCH 2 ] 2 CH 2 (R= Me 3 SiCH 2 ) with acetic acid. The crystal structures of 23, 24, and 28 are described and reveal that these compounds adopt double ladder structures. Depending on the identity of Z and R in chloroform solution the compounds are either dimers (n =2, 25-28) or tetramers (n= 4, 22-24). Also reported are preliminary studies on the catalytic activity in acylation reactions of compounds 22, 24-26, and 28.

Nuclear Magnetic Resonance (NMR) is a RF technique that is able to detect any compound by sensing the excited resonance signals from atomic nuclei having non-zero spin. NQR is similar to NMR but the only difference is NMR needs a DC magnetic field and due to this its application in the field is limited. A FPGA based NQR spectrometer is designed using a single FPGA chip to perform the digital tasks required for NQR spectrometer. Design of Probe for NMR/NQR spectrometer is researched. Parallel tuned and series tuned Probes are discussed and simulated.14N NQR from NaNO2 is observed from spectrometer designed with parallel tuned probe.

FruiteX-B ® -calcium fructoborate (FrxB) plant mineral complex was investigated in this study. Although calcium fructoborate is naturally-occurring and found in commonly ingested fruits and vegetables, the commercially produced FrxB calcium fructoborate complex is formed by a proprietary reaction of boric acid with fructose and calcium carbonate. Liquid and solid-state 13 C and 11 B NMR were utilized in order to establish a baseline standard of FrxB for product quality purposes, to establish a reliable methodology to positively identify and quantify amounts of FrxB present in tablets and capsules, liquids and powdered blends wherein the FrxB may have been mixed with other ingredients, excipients, or adulterants such as maltodextrin or magnesium stearate, and to establish a robust and reliable testing method for the identification and quantification of the mono-and the di-complexes of calcium fructoborate as well as any free borate and/or free fructose that may be present. The molar ratio of the various components of calcium fructoborate was studied by 11 B and 13 C NMR in order to establish the relative amounts of free borate, free fructose, and mono-ester/di-ester complex present in the material. A quantitative 11 B NMR method was developed to enable quantification of the amount of FrxB present in products wherein it had been tableted or encapsulated in combination with other dietary supplement ingredients, or excipients such as magnesium stearate or maltodextrin. A quantitative 13 C NMR method was developed to quantify free fructose content in the complex. Finally, an NMR based product stability study was performed to monitor molecular level stability of the complex at temperatures ranging from 35-70 ºC with exposures lasting from 2-18 hours.

The photoisomerization kinetics of trifloxystrobin (TFS) in acetone under artificial sunlight is reported. HPLC analysis showed the TFS, a strobilurine fungicide of EE conformation, was converted into an equilibrium mixture of four isomers after illumination for 7 h. The isomers were identified as EZ, EE, ZZ, and ZE and were separated in the crystalline form by preparative HPLC and characterized by use of a variety of spectroscopic techniques. The quantum yield and reaction constants for the isomerization reactions were determined. The detailed spectral features of the individual isomers measured by UV, IR, Raman, NMR and mass spectroscopy are presented and compared. The spectra of the isomers were found to be very characteristic, with good analytical significance.

Arterial spin labeling (ASL) offers MRI measurement of cerebral blood flow (CBF) in vivo, and may offer clinical diagnostic utility in populations such as those with early Alzheimer's Disease (AD). In the current study, we investigated the reliability and precision of a pseudo-continuous ASL (pcASL) sequence that was performed two or three times within one hour on eight young normal control subjects, and 14 elderly subjects including 11 with normal cognition, 1 with AD and 2 with Mild Cognitive Impairment (MCI). Six of these elderly subjects including 1 AD, 2 MCIs and 3 controls also received 15 O-water positron emission tomography (PET) scans two hours before their pcASL MR scan. The instrumental reliability of pcASL was evaluated with the intraclass correlation coefficient (ICC). The ICCs were greater than 0.90 in pcASL global perfusion measurements for both the young and the elderly groups. The cross-modality perfusion imaging comparison yielded very good global and regional agreement in global gray matter and the posterior cingulate cortex. Significant negative correlation was found between age and the gray/white matter perfusion ratio (r = −0.62, P<0.002). The AD and MCI patients showed the lowest gray/white matter perfusion ratio among all the subjects. The data suggest that pcASL provides a reliable whole brain CBF measurement in young and elderly adults whose results converge with those obtained with the traditional 15 O-water PET perfusion imaging method. pcASL perfusion MRI offers an alternative method for non-invasive in vivo examination of early pathophysiological changes in AD.

Bismaleimides with main chains of different structures were prepared by the reaction between maleic anhydride and various diamines and by the reaction between 4-maleimidobenzoylchloride and 3,5-dihidroxybenzoic acid. The monomers were characterized with IR and 1 H-NMR spectroscopy. Polymers based on these compounds were prepared through the Michael addition of diamines to bis-maleimides. The thermal characterization of the monomers and polymers was performed with differential scanning calorimetry and dynamic thermogravimetric analysis.

Measurements of rates of glucose uptake and of glycerol and ethanol formation combined with knowledge of the metabolic pathways involved in S. cerevisiae were employed to obtain in vivo rates of reaction catalysed by pathway enzymes for suspended and alginate-entrapped cells at pH 4.5 and 5.5. lntracellular concentrations of substrates and effectors for most key pathway enzymes were estimated from in vivo phosphorus-31 nuclear magnetic resonance measurements. These data show the validity in vivo of kinetic models previously proposed for phosphofructokinase and pyruvate kinase based on in vitro studies. Kinetic representations of hexokinase, glycogen synthetase, and glyceraldehyde 3phosphate dehydrogenase, which incorporate major regulatory properties of these enzymes, are all consistent with the in vivo data. This detailed model of pathway kinetics and these data on intracellular metabolite concentrations allow evaluation of flux-control coefficients for all key enzymes involved in glucose catabolism under the four different cell environments examined. This analysis indicates that alginate entrapment increases the glucose uptake rate and shifts the step most influencing ethanol production from glucose uptake to phosphofructokinase. The rate of ATP utilization in these nongrowing cells strongly limits ethanol production at pH 5.5 but is relatively insignificant at pH 4.5.

Despite its well-documented limitations, colorimetry has been commonly used for the d-xylose test in the diagnosis of malabsorption syndrome (MAS). With a possibility of overcoming its limitations, the use of 1H NMR spectroscopy for D-xylose test is explored herein. Urine samples from 35 adults with suspected MAS were obtained before and after oral ingestion of D-xylose. The diagnosis of MAS was based on fecal fat (72 h excretion using Van de Kamer's technique, normal < 7 g/24 h and/or Sudan III stain of spot stool specimen, normal≤10 droplets/high power field) and/or endoscopic duodenal biopsy. Urinary excretion of D-xylose over 5 h after consumption of 5 g D-xylose, using both colorimetry and NMR was compared (normal≥1 g/5 g/5 h). In vitro experiments on the standard specimens of D-xylose were also performed independently using both methods. Colorimetry showed a lower value for the quantity of D-xylose excreted in urine than NMR [median 0.73 (0.17–1.89 g) vs 1.37 (0.17–3.23 g), respectively; p<0.0001, Wilcoxon's signed ranks test]. Colorimetry and NMR correctly diagnosed 11/12 and 10/12 (p=N.S.) patients with MAS and 14/23 and 20/23 (p<0.05) without MAS, respectively. Sensitivity and specificity of colorimetry and NMR were 91.6 and 60.7% vs 83.3 and 86.9%, respectively. In in vitro experiments, the values obtained for standard xylose using NMR showed a maximum error of 7%, whereas the colorimetric method showed 20%. The NMR method is simple and may be more accurate for the D-xylose absorption test. Colorimetry was found to be inferior as compared with NMR due to its low specificity. Copyright © 2004 John Wiley & Sons, Ltd.

We evaluated polyacrylamide gel electrophoresis (PAGE) and size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) approaches to determine weight-average molecular weight (M w ) and polydispersity (PD) of heparins. A set of unfractionated heparin sodium (UFH) and low-molecularweight heparin (LMWH) samples obtained from nine manufacturers which supply the US market were assessed. For SEC-MALLS, we measured values for water content, refractive index increment (dn/dc), and the second virial coefficient (A 2 ) for each sample prior to molecular weight assessment. For UFH, a mean±standard deviation value for M w of 16,773±797 was observed with a range of 15,620 to 18,363 (n=20, run in triplicate). For LMWHs by SEC-MALLS, we measured mean M w values for dalteparin, tinzaparin, and enoxaparin of 6,717±71 (n=4), 6,670±417 (n=3), and 3,959±145 (n=3), respectively. PAGE analysis of the same UFH, dalteparin, tinzaparin, and enoxaparin samples showed values of 16,135±643 (n=20), 5,845±45 (n=4), 6,049±95 (n=3), and 4,772±69 (n=3), respectively. These orthogonal measurements are the first M w results obtained with a large heparin sample set on product being marketed after the heparin crisis of 2008 changed the level of scrutiny of this drug class. In this study, we compare our new data set to samples analyzed over 10 years earlier. In addition, we found that the PAGE analysis of heparinase digested UFH and neat LMWH samples yield characteristic patterns that provide a facile approach for identification and assessment of drug quality and uniformity.

Current cancer research is being increasingly focused on the study of distinctive characters of tumour metabolism, resulting in a switch from oxidative phosphorylation to glycolysis (Warburg effect). Isoform 5 of human lactate dehydrogenase (hLDH5), which catalyzes the final step in the glycolytic cascade (pyruvate to lactate), constitutes a relatively new and untapped anti-cancer target. In this study, careful design and synthesis of a selected series of aryl-substituted N-hydroxyindole-2-carboxylates (NHIs) has led to several hLDH5-inhibitors, showing "first-in-class" potency and isoform selectivity. Enzyme kinetics studies indicated that these inhibitors exhibit a competitive mode of inhibition. Some representative examples were tested against two human pancreatic carcinoma cell lines, and displayed a good antiproliferative activity, which was even more evident under hypoxic conditions.

A complete series of dppfMX 2 (M=Pt, Pd; X= Cl, Br, I) compounds have been synthesized using different routes, and characterized fully. The synthesis of dppfPdI 2 has been achieved by reacting Pd(COD)Cl 2 with dppf in the presence of NaI. X-ray structures of dppfPdBr 2 and dppfPdI 2 have also been reported for the first time in this study. A preliminary Suzuki coupling screening study reveals that dppfPdX 2 compounds are superior to the conventional Ph 3 P-based catalysts and bidentate phosphine-based ligands. Reactions carried out under in situ conditions also gave a similar trend, but their respective activities were much lower than that of the fully formed catalysts.

Leaves of Punica granatum contain the new gallotannins, 1,2,4-tri-O-galloyl-β-glucopyranose and 1,3,4-tri-O-galloyl-β-glucopyranose together with the hitherto unknown ellagitannins, 1,4-di-O-galloyl-3,6-(R)-hexahydroxydiphenyl-β-glucopyranose and brevifolin carboxylic acid 10-monopotassium sulphate. Structures were established by conventional methods of analysis and confirmed by 1H, 13C NMR, 2D-chemical shift correlation NMR and ESI-MS (negative mode) spectrometric analysis.

Motor imagery is a mental rehearsal of simple or complex motor acts without overt body movement. It has been proposed that the association between performance and the mental rehearsal period that precedes the voluntary movement is an important point of difference between highly trained athletes and beginners. We compared the activation maps of elite archers and nonarchers during mental rehearsal of archery to test whether the neural correlates of elite archers were more focused and efficiently organised than those of nonarchers. Brain activation was measured using functional MRI in 18 right-handed elite archers and 18 right-handed nonarchers. During the active functional MRI imagery task, the participants were instructed to mentally rehearse their archery shooting from a first-person perspective. The active imagery condition was tested against the nonmotor imagery task as a control condition. The results showed that the premotor and supplementary motor areas, and the inferior frontal region, basal ganglia and cerebellum, were active in nonarchers, whereas elite archers showed activation primarily in the supplementary motor areas. In particular, our result of higher cerebellar activity in nonarchers indicates the increased participation of the cerebellum in nonarchers when learning an unfamiliar archery task. Therefore, the difference in cerebellar activation between archers and nonarchers provides evidence of the expertise effect in the mental rehearsal of archery. In conclusion, the relative economy in the cortical processes of elite archers could contribute to greater consistency in performing the specific challenge in which they are highly practised.

Nuclear magnetic resonance (NMR) based metabolomics in combination with multivariate data analysis may become valuable tools to study environmental effects of pharmaceuticals and other chemicals in aquatic organisms. To explore the usefulness of this approach in fish, we have used 1 H NMR metabolomics to compare blood plasma and plasma lipid extracts from rainbow trout exposed to the synthetic contraceptive estrogen ethinylestradiol (EE 2 ) with plasma from control fish. The plasma metabolite profile was affected in fish exposed to 10 ng/L but not 0.87 ng/L of EE 2 , which was in agreement with an induced vitellogenin synthesis in the high dose group only, as measured by ELISA. The main affected metabolites were vitellogenin, alanine, phospholipids and cholesterol. The responses identified by this discovery-driven method could be put in context with previous knowledge of the effects of estrogens on fish. This adds confidence to the approach of using NMR metabolomics to identify environmental effects of pharmaceuticals and other contaminants.

~H and ~3C nuclear magnetic resonance (NMR) spectra of phosphatidylethanolamine plasmalogen were studied. Resonances in both spectra were assigned by conventional one-and two-dimensional NMR techniques. Distinctive signals corresponding to the olefinic carbons near the vinyl ether group were shown to be the most useful in both qualitative and quantitative analysis, The plasmalogen content in different fish lipid samples, as determined by ~3C-NMR spectro'scopy, was in good agreement with the data obtained by gas chromatograpy.

Orientational order parameters determined from (1)H NMR spectroscopy of solutes in liquid crystals that form both nematic and smectic A phases are used to determine the solute smectic A order parameters and the smectic-nematic coupling term. For the analysis, it is necessary to know the nematic part of the potential in the smectic A phase: various ways of extrapolating parameters from the nematic phase to the smectic phase are explored.

As revealed by NMR spectroscopy (after ultrasonic degradation) and HPLC (after total hydrolysis) an arabinoxylan (AX) containing 74.8% Xylp and 23.2% Araf was isolated from Ispaghula (Plantago ovata) by soaking the seed husk with water, extraction with aqueous sodium hydroxide and coagulation with acetic acid. The AX with a molar mass of 364,470 g/mol shows high swelling ability in water. The carboxymethylation of AX was carried out heterogeneously with sodium monochloroacetate in the presence of aqueous sodium hydroxide. The reaction parameters were varied in terms of slurry medium, molar ratio, temperature, time, and sodium hydroxide concentration. For comparative studies, carboxymethylation of arabinan was carried out. In order to determine the total degree of substitution (DS) and mole fractions of the repeating units of carboxymethyl arabinoxylan (CMAX) and of carboxymethyl arabinan, HPLC and 1 H NMR spectroscopic investigations after total hydrolysis were carried out. DS values for CMAX as high as 1.81 were achieved. CMAX is water soluble starting at DS of 0.33.

Determining the degree of the crosslinking of resins in intermediate-product used in the manufacturing of abrasive articles is difficult and complicated because of the presence of different components in the material. The abrasive articles consist of abrasive (e.g., fused alumina), filler (e.g., potassium fluoroborate-KBF 4 , pyrite-FeS 2 ), wetting agent (e.g., resol), and binder (e.g., novolak). Proper hardening of intermediate-product is a very important stage dur-ing production of abrasive tools. The hardening process depends on crosslinking of resins. Following were used to study crosslinking of resins: IGC, washing away method, NMR broad line, DSC, and FTIR methods.

Hydrogen and carbon NMR spectroscopy have been used to investigate the chemical modi®cation process of titanium isopropoxide by acetic acid. The spectra con®rm the belief that the titanium isopropoxide exchanges isopropyl groups with modifying acetate groups to form a molecule with approximate stoichiometry Ti(OiPr) 2 (OAc) 2 . This stoichiometry results even when enough acetic acid is present in solution to allow for signi®cantly higher isopropyl replacement. In addition, progressive esteri®cation to form isopropyl acetate results in a gradually increasing level of condensation and oxo-bridging between the Ti oligomers. Throughout the condensation process, the remaining Ti-bound acetate and isopropyl groups maintain an approximate 1 : 1 ratio, suggesting that oxo-bridge formation occurs through a transesteri®cation process. #

This review deals with the effect of variations in phospholipid and sterol structure on the nature and magnitude of lipid-sterol interactions in lipid bilayer model membranes. The first portion of the review covers the effect of Chol itself on the thermotropic phase behavior and organization of a variety of different glycero-and sphingolipid membrane lipid classes, varying in the structure and charge of their polar headgroups and in the length and structure of their fatty acyl chains. The second part of this review deals with the effect of variations in sterol structure on the thermotropic phase behavior and organization primarily of the well studied DPPC model membrane system. In the third section, we focus on some of the contributions of sterol functional group chemistry, molecular conformation and dynamics, to sterollipid interactions. Using those studies, we re-examine the results of recently published experimental and computer-modeling studies to provide a new more dynamic molecular interpretation of sterol-lipid interactions. We suggest that the established view of the rigid sterol ring system and extended alkyl side-chain obtained from physical studies of cholesterol-phospholipid mixtures may not apply in lipid mixtures differing in their sterol chemical structure. L is lauroyl, M is myristoyl, P is palmitoyl, S is stearoyl, A is arachidoyl, E is elaidoyl and O is oleoyl (DMPC is dimyristoylphosphatidylcholine, etc.); LC , lamellar crystalline phase with tilted hydrocarbon chains; L ␤ or L ␤ , planar lamellar gel state with tilted or untilted hydrocarbon chains, respectively; P ␤ , rippled gel state with titled hydrocarbon chains; L␣, lamellar liquid-crystalline state; Lo or L d , lamellar liquid-ordered or liquid-disordered state, respectively; Tp and Tm, the pretransition and main phase transition temperature, respectively; Hp and Hm, enthalpy of the pretransition and main phase transition, respectively; T 1/2 , width of the DSC endotherm at half height ( • C), which is inversely related to the cooperativity of the phase transition; Tm shp , phase transition temperature of the sharp component of the DSC endotherm corresponding to the sterol-poor bilayer regions; Tm brd , phase transition temperature of the broad component of the DSC endotherm corresponding to the sterol-rich bilayer regions; Hm shp , phase transition enthalpy of the sharp component of the DSC endotherm corresponding to the sterol-poor bilayer regions; Hm brd , phase transition enthalpy of the broad component of the DSC endotherm corresponding to the sterol-rich bilayer regions; DSC, differential scanning calorimetry; FTIR, Fourier transform infrared; NMR, nuclear magnetic resonance.

The chemical analysis of a sample of D 9 -THC, which had been stored in an ethanol/propylene glycol solution for 5 years, resulted in the isolation of several hydroxylated D 9 -THC derivatives, the main of which were trans-cannabitriol monoethyl ether (4) and trans-propanediol ethers 7 and 8. cis-Cannabitriol monoethyl ether (5) and the oxidised derivatives 3 and 6 were detected in lesser amounts. The structure elucidation of the unprecedented cannabinoids 3, 5, 7 and 8 was achieved mainly by NMR techniques. Full NMR assignment of compounds 4 and 6 were also made. The detection of cannabitriol (6) and the corresponding solvent-adduct analogues (compounds 4e8) was in agreement with the decomposition mechanisms previously proposed for D 9 -THC. The isolation of the endoperoxide 3 represents indirect evidence of the existence of unstable precursors that were suspected to be intermediates in the non-enzymatic oxidation pathway of D 9 -THC. Both isomers of cannabitriol monoethyl ether exhibited weak affinity at either CB 1 (K i ¼2.25, 6.30 mM) or CB 2 cannabinoid receptors (K i ¼1.97, 3.13 mM), the trans isomer always being more potent than the cis isomer.