Determination of lipase activity in porcine pancreas and clinical analysis of lipase in human serum with surface acoustic wave enzyme sensor system

A new kind of surface acoustic wave (SAW) enzyme sensor system has been applied to the assay of extracted lipase activity based on triacetin solution as substrate. A linear relationship between the frequency change and the enzyme activity up to 500 U/L has been obtained, and the detection limit has been evaluated to 0.3 U/L. Kinetic parameters of the extracted lipase as well as that of the standard enzyme have been estimated. The effects of temperature, pH value and surfactants have been investigated. A comparison between SAW sensor system and the conductometric method has been carried out. The technique has been applied to the determination of lipase activity in serum samples. Received: 17 January 1995 / Revised: 9 March 1995 / Accepted: 16 March 1995 Correspondence to: Shouzhuo Yao     

Reductive amination ofl-menthol by aliphatic nitriles

The reductive amination ofl-menthol with aliphatic nitriles has been studied. A probable scheme of the mechanism of the reaction has been put forward and the stereochemical composition of its products has been determined. It has been established with the aid of the¹³C NMR method that the reaction forms a mixture of isomeric optically-active N-alkylmenthyl-, -neomenthyl-, -isomenthyl-, and-neoisomenthyl-amines in a ratio of 54:24:17:5. The absolute configurations of the amines obtained have been determined.     

Polysaccharide from the leaves ofPhytolacca americana

A polysaccharide has been isolated from the leaves ofPhytolacca americana and has been characterized. It has been established that it contains residues of galactose, arabinose, xylose, and rhamnose, in a ratio of 3:4:1:3 and also D-galacturonic acid (85–90%). The results obtained permit the polysaccharide to be assigned to the class of pectin substances.     

Tritium-labeled 5-oxo-Pro-Arg-Pro

Conditions of tritium introduction into 5-oxo-Pro-Arg-Pro have been developed. Labelled 5-oxo-Pro-Arg-Pro has been obtained in 75% yield and molar radioactivity of 60 Ci/mmol. Tritium distribution over amino acid residues in the peptide has been determined. 5-Oxo-Pro : Arg : Pro ratio in the labelled peptide has been found to be 1 : 5.2 : 2.8. Nonterminal amino acid has been found to contain the major portion of tritium, about 35 Ci/mmol; i.e., arginine includes more than half of the label. Such a feature can be explained by the effect of readily protonated guanidine group of arginine. The influence of charged guanidine group of arginine seems to increase the shift of electron density in the neighboring C–H bonds of arginine and proton mobility, thus increasing protium–tritium exchange at these carbon atoms.     

Behavior of a nickel electrode in the presence of carbon monoxide

The electrochemical behavior of a nickel electrode with limited volume (LVE) electrodeposited as a thin layer on gold has been studied. The influence of the gold matrix on the electrochemical Ni electrode behavior has been considered. The electrosorption and oxidation of carbon monoxide on the Ni surface and its influence on hydrogen sorption has also been demonstrated. Received: 21 May 1997 / Accepted: 9 June 1997     

Rovibrational spectra of bounded diatomic molecules

Spectra of a bounded diatomic molecule is studied numerically. Shifted Deng–Fan oscillator potential has been used to model the molecule. The accurate five‐point finite difference method has been used to solve the Schrödinger equation for rovibrational motion of the molecule. The energies of the bound states as well as free states of the molecule have been calculated. In addition, radial matrix elements like , n = 1, 2, and 3 have been calculated. These have been used to calculate the ‐pole static polarizabilities. The variation of bound state energies, matrix elements and ‐pole static polarizabilities with the boundary radius has also been studied. The Stark effect in case of this bounded system has also been investigated.     

Application of time-resolved,laser-induced and fiber-optically guided fluorescence for monitoring of a PAH-contaminated remediation site

A fiber-optical sensor system for the on-line and in situ detection of aquatic polycyclic aromatic hydrocarbons (PAH) has been described. Detection limits in the ng l⁻¹ range have been obtained using time-resolved laser-induced fluorescence spectroscopy. The method has been applied to the detection of pyrene in real samples from a contaminated area. Interferences from humic material has been eliminated by the use of chemometric methods such as three dimensional least squares and partial least squares. Received: 18 January 1995 / Revised: 3 March 1995 / Accepted: 10 March 1995 Correspondence to: R. Niessner     

Chemical examination of Tylophora asthmatica—II

Tylophorine has been degraded to a compound, identified as 2:3:6:7-tetramethoxy-9-methylphenanthrene. In conjunction with other degradation results and biogenetic considerations, tylophorine is now formulated as 2:3:6:7-tetramethoxyphenanthro(9:10:6′:7′)indolizidine.

A synthesis of the basic ring system, phenanthro-(9:10:6′:7′)indolizidine, present in tylophorine has been achieved.     

Novel calix[4]arene based metallo-supramolecular complex for recognition of cyanide ions in aqueous medium

A novel bis-naphthalimidocalix[4]arene-Cu(II) supramolecular complex has been observed to provide an efficient recognition system for CN^? ions in aqueous medium. The binding stoichiometry of bis-naphthalimidocalix[4]arene and copper ion has been found to be 1:1 while that for bis-naphthalimidocalix[4]arene-Cu(II) and cyanide ion it has been determined to be 1:2.     

Polyamides from 12-(β-aminoethyl) abietan-18-amine

The 1:1 salt of 12-(β-aminoethyl)abietan-18-amine and adipic acid has been prepared and polymerized. This salt has been copolymerized with the 1:1 salt of hexamethylenediamine and adipic acid. 12-(β-Aminoethyl)abietan-18-amine has been polymerized with isophthaloyl and terephthaloyl chlorides with triethylamine as catalyst and terpolymerized with terephthaloyl chloride and hexamethylenediamine. All polymers have been characterized to some extent, and mechanical properties are reported for two of the polyamide films.     

Extraction-spectrophotometric and radiometric investigation of the ternary ion-association complex of niobium(V) with pyrocatechol and triphenyl-tetrazolium chloride

The optimum conditions for extraction of niobium(V) as a ternary ion-association complex with pyrocatechol and triphenyltetrazolium chloride(TTC) have been determined. The investigation of the composition has shown that the ratio Nb:proocatechol:TTC is 1:2:1 K_ex, K_D and have been determined radiometrically, using the chemical model. The influence of foreign ions on the extraction of the ion-association complex has been studied. A method for artifical mixture and steel containing niobium has been used.     

Stereospecific analysis of the triacylglycerols of cottonseed oil

A stereospecific analysis has been made of the triacylglycerols of cottonseed oil, as a result of which it has been established that the saturated and 16:1 acids mainly occupy the sn-1 position, while 18:1 and 18:2 acids esterify the sn-2 and sn-3 positions of the triacylglycerides to equal extents.     

Reductive amination ofl-menthol by aliphatic nitriles

The reductive amination ofl-menthol with aliphatic nitriles has been studied. A probable scheme of the mechanism of the reaction has been put forward and the stereochemical composition of its products has been determined. It has been established with the aid of the¹³C NMR method that the reaction forms a mixture of isomeric optically-active N-alkylmenthyl-, -neomenthyl-, -isomenthyl-, and-neoisomenthyl-amines in a ratio of 54:24:17:5. The absolute configurations of the amines obtained have been determined.Institute of Physical Organic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Institute of Chemical and Biological Physics, Academy of Sciences of the Estonian SSR, Tallin. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 312–317, May–June, 1981.     

Chelate formation of ammonium aurintricarboxy-late with bivalent copper : Physico-chemical investigation of the composition,structure and stability

The formation of a coloured chelate, having λmax at 540 mμ, between cupric ions and ammonium aurintricarboxylate has been reported. It has been concluded that only one complex having metal : reagent ratio of 1:2 is formed in solution. The method adopted for investigation has been the continuous variation method, using spectrophotometric and electrical conductance measurements. It has been observed that there is an increase in acidity on mixing the reactants, which shows that hydrogen ions are liberated as a result of chelation It has been suggested that chelation occurs between the phenolic oxygen and the adjacent carboxylic oxygen.A method has been presented for the calculation of formation constant from spectrophotometric data and the value of K in the case of the chelate investigated has been calculated to be 6.45.10⁸. The free energy of formation works out to be —14.6 kcal at 25°C.     

Spectrophotometric study of the reaction of gallium(III) with xylenol orange

The formation of complexes between gallium(III) and Xylenol Orange at pH 2 has been studied. Complexes with the mole ratio 1:1 and 1:2 have been found and the respective formation constants determined. The latter complex, for which the absorption spectrum has been calculated, is suitable for the spectrophotometric determination of gallium, and optimum conditions for its formation have been established.     

Theoretical study of the 1:1 and 2:1 (homo- and heterochiral) complexes of XOOX' (X, X' = H, CH3) with lithium cation

A theoretical study of the 1:1 and 2:1 complexes of XOOX' (X, X' = H, CH(3)) with the lithium cation has been carried out by means of ab initio computational methods up to the MP2/aug-cc-pVTZ level. The optical rotatory power and NMR parameters (absolute chemical shielding and indirect coupling constants) have been calculated. In addition, the racemization barriers within the complexes formed have been evaluated. Special attention has been paid concerning the differences between the 2:1 homo- and heterochiral complexes.     

Fracture behavior–morphology relationships in an unsaturated polyester resin modified with a liquid oligomer

An unsaturated polyester (UP) resin modified with a liquid polymer, polyoxypropylenetriamine (POPTA), at a concentration of 10 wt% has been precured at several temperatures. Phase separation takes place before gelation at all precure temperatures used. The glass‐transition region has been analyzed by dynamic mechanical analysis. Mechanical properties have been related to microstructural features. With a precure temperature fixed, the unsaturated polyester (UP) resin has also been modified with different contents of POPTA. Fracture toughness of the mixtures has also been analyzed and results are compared to those for the unmodified mixture. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1677–1685, 1999     

Cytotoxicity of PMMA-Based Nanoparticles Synthesized Adopting SDS and Tween 80

Summary: in this work the cytotoxicity of PMMA-based nanoparticles against mouse mammary cancer cells (4T1) has been investigated. NPs have been synthesized using either monomer starved semi-batch emulsion polymerization (MSSEP) or standard batch emulsion polymerization (BEP) processes adopting potassium persulfate (KPS) as initiator and two different emulsifiers: sodium dodecyl sulfate (SDS) and Tween 80. The toxicity of NPs produced using SDS has been confirmed in in vitro experiments while it has been found that NPs stabilized with Tween 80 show a good biocompatibility. Moreover, the absence of toxicity of NPs in which the SDS is substituted with Tween 80 adopting ion exchange resins (IER) has been proved. Finally the biocompatibility of the sulfate chain end groups coming from the adopted initiator has been assessed.     

Kinetically controlled phase transitions in liquid‐crystalline polymers. II. Isothermal degradation of ferroelectric switching in a chiral side‐chain polysiloxane during slow smectic B phase formation

The kinetics of phase transformations in a chiral siloxane polymer has been studied with an Avrami analysis of the differential scanning calorimetry data. Ferroelectric switching has been measured as a function of the driving voltage and temperature. The evolution of the switching at a constant temperature has been studied within the temperature range of the kinetically governed smectic C*/smectic B phase transition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1779–1784, 2005     

Disappearing and reappearing polymorphs. The benzocaine:picric acid system.

The low-melting polymorphic modification of the 1:1 complex of benzocaine (BC) and picric acid (PA) had earlier been reported to be an example of a "disappearing polymorph". The BC:PA system has been reinvestigated by thermomicroscopy, calorimetry, solid-state NMR, and X-ray crystallography. The phase diagram has been derived, and robust procedures for the crystallization of the two 1:1 complexes, a hydrate of the 1:1 complex, and a 2:1 complex have been devised. The structures of all four phases have been determined and compared using graph set analysis to characterize the hydrogen-bonding patterns. It is shown that the thorough microscopic investigation of the thermal behavior, combined with calorimetric methods, can lead to the development of strategies to crystallize metastable polymorphic forms which may be difficult to obtain once their stable congeners have been obtained.