摘要:

The PEGA resin, a beaded polyethylene glycol dimethylacrylamide copolymer, was evaluated as an affinity support for the purification of carbohydrate-binding macromolecules, namely, the cation-independent mannosyl phosphate receptor (CI-MPR) and a polyclonal antibody directed against aStreptococcusGroup A oligosaccharide. Two polyethylene glycol (PEG) derivatives, a di-acryloylated PEG1900derivative or a longer di-acryloylated PEG4000derivative, were used as cross-linkers. The longer cross-linker was synthesized in four steps from polyethylene glycol 4000. The mannosyl 6-phosphate (M6P)-containing immunoaffinity columns were prepared through the inverse suspension radical copolymerization of the corresponding allyl glycoside with acrylamide and the PEG cross-linker. The resin with the shorter cross-linker (PEG1900derivative) had a 6.3% molar cross-linking while that with the longer cross-linker (PEG4000derivative) had a 3.8% molar cross-linking. For theStreptococcusGroup A trisaccharide-containing immunoaffinity columns, three PEGA affinity supports bearing free amino groups were prepared and subsequently substituted with a trisaccharide activated as its squarate adduct. While one resin contained the shorter cross-linker PEG1900and had a 3% molar cross-linking, the other two resins contained the longer cross-linker PEG4000with a molar cross-linking of 5% and 3%, respectively. In affinity chromatographic studies, the M6P-containing columns were ineffective in retaining the cation-independent mannosyl phosphate receptor (CI-MPR, ~ 215kDa), whereas antibody (~ 150kDa) retention was observed with two of the threeStreptococcusGroup A trisaccharide-containing immunoaffinity columns.Key words: PEGA resins, immunoaffinity supports, carbohydrate ligands, antibody purification.

ISSN:0008-4042    

DOI:10.1139/v98-118

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The univariant (l1l2g) saturation vapor pressure of liquid deuterium oxide (phase l1) with liquid deuterium sulfide (phase l2) in equilibrium with a gas phase (g) has been measured in a stirred titanium reaction vessel at 19 temperatures from 33.003 to 18.905°C and at total pressures from 2.4500 to 1.7428 MPa. The univariant (hl1g) saturation vapor pressure of deuterium sulfide D-hydrate (phase h) in equilibrium with liquid deuterium oxide and a gas phase has been measured at 58 temperatures from 30.666 to 2.798°C and at pressures from 2.2959 to 0.11629 MPa. The maximum temperature for deuterium sulfide D-hydrate with a gas phase, the invariant quadruple pointQ(hl1l2g), has been determined from the cut of the (hl1g) and the (l1l2g) curves at temperature 30.770°C with standard error 0.0043°C and at pressure 2.3263 MPa with standard error 0.00018 MPa. The univariant (s1l1g) equilibrium of D-ice (phase s1) with liquid deuterium oxide and a gas phase containing deuterium sulfide has been measured at 11 temperatures from 3.8061 to 3.4540°C and at pressures between 0.00242 and 0.10542 MPa. The lowest temperature for stability of deuterium sulfide D-hydrate with liquid deuterium oxide, the invariant quadruple pointQ(hs1l1g), has been determined directly at 3.3917°C with standard error 0.0009°C and at pressure 0.12364 MPa with standard error 0.000011 MPa. This quadruple pointQ(hs1l1g) has also been defined by the cut of the (hl1g) and the (s1l1g) curves at temperature 3.3912°C with standard error 0.0006°C and at pressure 0.12363 MPa with standard error 0.000002 MPa. The deuterium sulfide - deuterium oxide gas mixture, represented by a Redlich-Kwong equation of state, has been used to evaluate the fugacities and compositions of the gaseous and liquid deuterium oxide phases for all equilibria. Raoult's law using fugacities has been used to evaluate the saturation mole fraction of deuterium oxide in liquid deuterium sulfide and the Henry's law constant for deuterium oxide solubility in liquid deuterium sulfide between 33.003 and 18.905°C. Data for the (l1l2g) and (s1l1g) equilibria have been accurately represented by simple two-parameter equations. Data for the (hl1g) equilibrium have required a model with seven significant parameters for proper representation betweem 30.666 and 2.798°C.Key words: deuterium sulfide - deuterium oxide system, clathrate D-hydrate of deuterium sulfide, deuterium sulfide D-hydrate stability, freezing of deuterium oxide - deuterium sulfide, phase equilibria of deuterium sulfide - deute

ISSN:0008-4042    

DOI:10.1139/v98-133

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Direct reactions of nickelocene and manganocene with molten pyrazoles in an inert atmosphere or under vacuum have led to the isolation of the following metal pyrazolate compounds: [Ni(4-Xpz)2]x(where X = H, Cl and pz = pyrazolate); [M(4-Xdmpz)2]x(where X = H, CH3, Cl, Br and M = Ni, Mn anddmpz = 3,5-dimethylpyazolate); and [Mn(4-Xpz)2(4-XpzH)]x(where X = Cl, Br and pzH = pyrazole). On the basis of indirect evidence all compounds are considered to have extended chain structures with metal ions linked in chains by double bridging pyrazolates. The two [Ni(4-Xpz)2]xcompounds are diamagnetic while all others are paramagnetic. Variable temperature magnetic susceptibility studies on the paramagnetic compounds reveal antiferromagnetic coupling between neighbouring metal ions. Analysis of the magnetic data (Hamiltonian of the form H = -2JsumSi·Sj) yields values of the exchange coupling constantJof -14 to -17 cm-1for the [Ni(4-Xdmpz)2]xcompounds, -1.2 to -2.1 cm-1for the [Mn(4-Xdmpz)2]xcompounds, and -0.41 cm-1for the [Mn(4-Xpz)2(4-XpzH)]xcompounds.Key words: nickel, manganese, manganocene, nickelocene, pyrazolates, antiferromagnetic exchange.

ISSN:0008-4042    

DOI:10.1139/v98-152

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Molecular orbital calculations are reported for N2H+and N2CH3+and for the transition structures for the rearrangement of these ions by 1,2-shifts of H and CH3. All reaction profiles were also calculated with one atom of noble gas, M, present (M = Ne, Ar, Kr). Structure optimizations were performed at B3LYP/6-311++G(d,p) and, in the case of N2H+···M, single point calculations were also performed at QCISD(T)(full)/6-311++G(2df,p). For N2H+, inclusion of one noble gas atom reduces the barrier to rearrangement from 46.6 kcal mol-1for the uncatalysed reaction to 42.6 kcal mol-1(by Ne), to 21.4 kcal mol-1(by Ar), and to 11.0 kcal mol-1(by Kr). For N2CH3+, the barrier of 36.4 kcal mol-1is reduced to 35.1 kcal mol-1by Ne, to 27.4 kcal mol-1by Ar, and to 18.4 kcal mol-1by Kr.Key words: catalysis, molecular orbital theory, argon, krypton.

ISSN:0008-4042    

DOI:10.1139/v98-119

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The electrochemical behaviour of silver was studied under cyclic voltammetry and chronoamperometry conditions in aqueous K2CrO4solutions. The forward cyclic voltammograms exhibited one oxidation peak, A1, due to the formation of Ag2CrO4. The height of the anodic peak, A1, increases with increasing chromate concentration, temperature, and scan rate. The solid films formed on the anode surface have been examined by X-ray diffractometry. The reverse voltammograms exhibited two reduction peaks, C1and C2, indicating the formation of two distinct surface layers of Ag2CrO4, an inner compact layer reduced in peak C1and an outer powdery layer reduced in peak C2.Key words: silver electrode, cyclic voltammetry, K2CrO4solutions.

ISSN:0008-4042    

DOI:10.1139/v98-149

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

An ultraviolet photoelectron (PE) spectrometer apparatus that utilizes a tuneable 50 W CW CO2laser as a directed heat source was used to study the vacuum pyrolysis of diazoacetophenone (1a) and itsp-methyl,p-methoxy,p-chloro, andp-nitro analogues1b,1c,1d, and1e. Analysis of the pyrolysate with He(I) ultraviolet PE spectroscopy shows that at a laser power level of 26 W (500 ± 50°C)1a,1b,1c, and1d, cleanly yield the corresponding phenylketenes2a,2b,2c, and2d, respectively, the products of the Wolff rearrangement of the incipient ketocarbenes. Of this group of highly reactive ketenes, which cannot be isolated in the condensed phase at ambient temperature, only2ahas been the subject of a previous PE spectroscopic study. But our work indicates that the sample of2aprepared in the earlier study was impure. The low volatility ofp-nitrodiazoacetophenone (1e) thwarted our attempts to generate2eand obtain its spectrum. Calculations at semiempirical (AM1) and ab inito (HF/6-31G(d)) levels of theory established that the diazoacetophenones prefer to adopt twistedsynconformations. That the calculated ionization potentials (HAM/3 and Becke3LYP/6-31+G(d)//HF/6-31G(d)) of1a-1dand the synthesized PE spectra of1a,1b, and1ccorrelate well with the PE spectroscopic data supports this finding. Shifts observed in the three low-energy ionizations of ketenes2b,2c, and2dinduced by thepara-substitution can be related to the character of the corresponding occupied molecular orbitals of phenylketene (2a).Key words: diazoacetophenones, phenylketenes, He(I) photoelectron spectroscopy, thermolysis, quantum chemical calculation

ISSN:0008-4042    

DOI:10.1139/v98-127

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The cyclic stannoxane obtained fromN-methyldiethanolamine and dibutyltin oxide reacts with 1H-pyrazole-3,5-dicarbonyl dichloride to afford the new 26-membered diaza tetraester crown3. In neutral medium, the above crown forms 1:2 solid dinuclear complexes with phenethylamine (3a) and homoveratrylamine (3b), which, after crystallization from acetonitrile, were isolated in high yield (90% and 85%, respectively). The3,3a, and3bstructures were identified from their analytical and spectroscopic (1H,13C NMR, and MS (FAB)) data. The spectroscopic properties of3aand3bare demonstrating that, in each complexation centre, simultaneously to the strong participation of the four pyrazole nitrogens, an additional weaker interaction between the aliphatic nitrogen of the side chain and the amine is involved. Comparison of the total interaction energies calculated (GenMol software) for phenethylamine-derived complex (3a) and homoveratrylamine-derived one (3b) suggests that theo-dimethoxy substitution of the guest aromatic ring could be improving the stability of3bin relation to3a.Key words: diazacrown, 1H-pyrazole, dinuclear, complexes, phenethylamines.

ISSN:0008-4042    

DOI:10.1139/v98-117

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

1-Acyl-2-arylhydrazines (1), readily obtained in high yield from the condensation of arylhydrazines and the appropriate liquid carboxylic acid (2), underwent reductive alkylation with the same or different liquid carboxylic acids (2) and NaBH4to give 1-acyl-2-alkyl-2-arylhydrazines (3) in good to moderate yields. The carboxylic acid has both the role of supplying the entering alkyl group and of acting as solvent. Most likely, it also modifies the BH4-anion to an active reducing agent under those conditions. The1H NMR criteria for identifying the location of acylation of hydrazines andEandZisomers are given. The MS spectra of the prepared hydrazides were analyzed in order to identify relevant structural features leading to specific fragmentations.Key words: 1-acyl-2-arylhydrazine, 1-acyl-2-alkyl-2-arylhydrazine, reductive alkylation, sodium tetrahydroborate, carboxylic acid.

ISSN:0008-4042    

DOI:10.1139/v98-125

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The influence of relative air moisture, temperature, and concentration of carbon dioxide on the carbonation of magnesium oxide and hydroxide have been studied in normal climatic conditions. The MgO and Mg(OH)2used for this original work are pure granular materials. The different species that appear during the process of carbonation and the most stable form in usual conditions of storage were identified. Moreover, the study of the different climatic factors showed that the carbonation is never complete even after a prolonged exposure.Key words: carbonation, magnesium oxide, magnesium hydroxide, storage, climatic conditions.

ISSN:0008-4042    

DOI:10.1139/v98-126

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Six leaf litter extracts (LLE) (eucalyptus (Eucaliptus globulus), fern (Pteridium aquilinium), oak (Quercus robur), chestnut (Castanea sátiva), laurel (Laurus nobilis), and ulex (Ulex europoeus) canopies) were isolated following an extraction procedure similar to that used for fulvic acids (FA) and were characterized by elemental analysis and UV-Vis, FT-IR, and synchronous molecular fluorescence (SyF) spectroscopies. Moreover, information about their interaction with the Cu(II) ion in aqueous solution (100 mg yL of LLE in 0.1 M KNO3at pH = 6) was obtained from the measurement of SyF spectra at increasing concentrations of Cu(II). These spectral sets were treated by a self-modeling mixture analysis method (SIMPLISMA) to obtain improved quenching profiles to be used in the estimation by the method of Ryan and Weber of the conditional stability constants (Kc), concentration of binding sites, and percentage of fluorescent binding sites accessible for complexation. For comparison purposes, two samples of FA extracted from two horizons of an oak forest soil (0-5 cm and 5-15 cm) were also studied. The spectroscopic data obtained for LLE and FA were different. The results suggest that LLE are characterized by relatively high concentrations of individualized simple molecules and include reactive structures (alkene and protein residues). The ratio of aliphatic yaromatic structures was higher in LLE than for FA. Both LLE and soil FA form stable complexes with Cu(II), but the logarithm of the conditional stability constant of the 1:1 complexes is larger for LLE (about 5) than for the soil FA (about 4.5).Key words: leaf litter extracts, soil fulvic acids, synchronous fluorescence, Cu(II) complexation, SIMPLISMA, spectral pattern recognition

ISSN:0008-4042    

DOI:10.1139/v98-150

出版商:NRC Research Press    

年代:1998

数据来源: NRC