A novel LIF-CE method for the separation of hyaluronan- and chondroitin sulfate-derived disaccharides: Application to structural and quantitative analyses of human plasma low- and high-charged chondroitin sulfate isomers

The report describes a rapid and simple CE method using LIF detection for the analysis of unsaturated disaccharides obtained from enzymatic depolymerization of plasma chondroitin sulfate (CS) isomers. The disaccharide reducing groups were labeled with 2-aminoacridone (AMAC). The fluorotagged products can be separated by reversed-polarity CE using a sodium acetate buffer, pH 3.8, in the presence of 0.05% methylcellulose. The choice of the appropriate electrophoretic conditions was performed after a deep analysis of the most important parameters affecting analyte separation. In particular, the effect of both run buffer concentration and pH on resolution, efficiency, migration times, and peak area was evaluated. The selected electrophoretic conditions allowed us to separate the CS isomers-derived Delta-disaccharides in less than 12 min, also resolving the nonsulfated disaccharides released from CS isomers from those released from hyaluronan (HA). Moreover, these conditions gave a good reproducibility of both the migration times (CV%, 0.25) and the peak areas (CV%, 1.4). Intra- and interassay CV were 5.37 and 7.23%, respectively, and analytical recovery was about 86%. The applicability of the above method to the quantitative and structural disaccharide analyses of plasma CS isomers was investigated. Data obtained from 44 healthy human subjects were compared with those obtained by a fluorophore-assisted carbohydrate electrophoresis (FACE) reference assay, by using the Passing and Bablok regression and Bland-Altman tests. The developed method could represent a good tool for an ultrasensitive analysis of CS isomers in biological samples from different sources, particularly when samples are available in very low amounts.     

Synthesis, reactivity, electrochemical behavior, and crystal structure of a family of multivalent metal carbido-carbonyl clusters based on the rh(10)(c)(2)au(4-6) framework

Six metal carbido-carbonyl clusters have been isolated and recognized as members of a multivalent family based on the dioctahedral Rh(10)(C)(2) frame, with variable numbers of CO ligands, AuPPh(3) moieties, and anionic charge: [Rh(10)(C)(2)(CO)(x)(AuPPh(3))(y)](n-) (x = 18, 20; y = 4, 5, 6; n = 0, 1, 2). Anions [Rh(10)(C)(2)(CO)(18)(AuPPh(3))(4)](-) ([2](-)) and [Rh(10)(C)(2)(CO)(18)(AuPPh(3))(4)](2-) ([2](2-)) have been obtained by the reduction of [Rh(10)(C)(2)(CO)(18)(AuPPh(3))(4)] (2) under N(2), while [Rh(10)(C)(2)(CO)(18)(AuPPh(3))(5)](-) ([3](-)) was obtained from [Rh(10)(C)(2)(CO)(20)(AuPPh(3))(4)] (1) by reduction under a CO atmosphere. [3](-) can be better obtained by the addition of AuPPh(3)Cl to [2](2-). [Rh(10)(C)(2)(CO)(18)(AuPPh(3))(6)] (4) is obtained from [3](-) and 2 as well by the reduction and subsequent addition of AuPPh(3)Cl. The molecular structures of [2](2-) ([NBu(4)](+) salt), [3](-) ([NMe(4)](+) salt), and 4 have been determined by single-crystal X-ray diffraction. The redox activities of complexes 1, 2 and [3](-) have been investigated by electrochemical and electron paramagnetic resonance (EPR) techniques. The data from EPR spectroscopy have been accounted for by theoretical calculations.     

Platinum(II) iodide complexes with propan-1-amine

Summary Thecis-[PtPra₂I₂],trans-[PtPra₂I₂], [PtPra₃I]I, [PtPra₄]I₂ and [PtPra₄]I₂ · 2H₂O (Pra = propan-1-amine) complexes have been prepared and characterized by elemental analyses, i.r. and¹H n.m.r. spectra and t.g., d.t.g. and d.t.a. measurements. Thermal degradation of the 13 and 14 complexes yieldstrans-[PtPra₂I₂] as an intermediate, whereascis-[PtPra₂I₂] isomerizes totrans without decomposition. The¹H n.m.r. spectra of the 12 and 14 species in deuteriated solvents are characteristic of the stoichiometry and geometry, whereas the spectra of [PtPra₃I]I indicate a general instability of this complex in solution, owing to easy decomposition to give trans-[PtPra₂I₂].     

Platinum(II) halide complexes with propan-1-amine

Summary The complexescis-[PtPra₂X₂],trans-[PtPra₂X₂], [PtPra₃X]X, [PtPra₄]X₂ and [PtPra₄]X₂ · 2H₂O, where Pra= propan-1-amine and X=Cl or Br, have been prepared with good yields and characterized by thermal analysis and i.r. and¹H n.m.r. spectroscopy. The best methods to obtain the pure products are discussed. The TG and DTA data are reported for all the complexes; in particular the thermal degradation of the 13 and 14 bromo-derivatives allows to isolate the intermediatetrans-[PtPra₂Br₂]. The i.r. spectra are characteristic of geometry and stoichiometry, as the¹H n.m.r. spectra ofcis-[PtAm₂Br₂],trans-[PtAm₂Br₂], [PtAm₃Br]Br and [PtAm₄]Br₂ (Am=propan-1-amine or hexan-1-amine) in deuteriated benzene, acetone and chloroform.     

Second-harmonic generation in surface periodically poled lithium niobate waveguides: on the role of multiphoton absorption

Second-harmonic generation is investigated in lithium niobate channels realized by proton exchange and quasi-phase matched by surface periodic poling. The reduction in conversion efficiency at high powers is interpreted in terms of multiphoton absorption via two-color terms, yielding an estimate of the dominating three-photon process.     

Association of Molybdenum Ionic Species with Alumina Surface

The adsorption isotherms at 25, 45, and 65 degrees C of molybdenum solutions of concentration ranges between 10(-3) and 3x10(-2) M(Mo) (pH 4-5) on different alumina samples are investigated. The analysis is conducted using a modified Frumkin isotherm which takes a more realistic account of the lateral interaction between adsorbed species and considers that the adsorption takes place on the most basic OH groups on the surface of alumina. The results are discussed in view of the difference in solutions speciation, and the changes in the pH of the remaining supernatant solutions. The solution temperature, PZC of the used aluminas, the configuration of the basic OH groups on their surface, and the pore structure have been shown to intervene effectively. Copyright 2000 Academic Press.     

Platinum-dihalide complexes with N-alkyl O-ethylthiocarbamates

Summary The thiocarbamic esters (L)ETC(EtOSCNHEt) and PTC (EtOSCNHPr) act as sulphur donors towards platinum halides, yielding the cis-[Pt(L)₂Cl₂], trans-[Pt(L)₂Br₂], [Pt(L)₃X]X (X = Cl or Br) and [Pt(L)₄]X₂ (X = Cl, Br or I) complexes. By addition of n-hexane to platinum chloride solutions in pure ligands the 16 adducts [Pt(L)₄]-Cl₂·2L have been isolated. The non-bonded ligand molecules are easily released to give the corresponding 14 complexes. The compounds have been characterized by elemental analysis and spectroscopy. The 14 and 16 complexes decompose in benzene to form the 13 species, except for [Pt(ETC)₄]I₂, which releases two ligand molecules to give trans-[Pt(ETC)₂I₂]. The 12 and 13 complexes have been tested for in vitro cytostatic activity against KB cells.     

Bloch analysis of finite periodic microring chains

We apply Bloch analysis to the study of finite periodic cascading of microring resonators. Diagonalization of the standard transfer matrix approach not only allows one to find an exact analytic expression for transmission and reflection, but also to derive a closed form solution for the field in every point of the structure. To gain more physical insight we have analyzed the main features of the transmission resonances in a finite chain and we have given some hints for their experimental verification . PACS 42.70.Qs; 42.82.Gw; 42.60.Da