Dose and timing of the first light fraction in two-fold illumination schemes for topical ALA-mediated photodynamic therapy of hairless mouse skin

A fractionated illumination scheme in which a cumulative fluence of 100 J cm(-2) is delivered in two equal light fractions separated by a dark interval of 2 h has been shown to considerably increase the efficacy of 5-aminolevulinic acid (ALA)-photodynamic therapy (PDT). The efficacy of such a scheme is further increased if the fluence of the first light fraction is reduced to 5 J cm(-2). We have investigated the relationship between the PDT response and the kinetics of protoporphyrin IX (PpIX) fluorescence in the SKH1 HR hairless mouse for first fraction fluences below 5 J cm(-2) delivered 4 h after the application of ALA and 10 J cm(-2) delivered 2 h after the application of ALA. Illumination is performed using 514 nm at a fluence rate of 50 mW cm(-2). Reducing the fluence of the first fraction to 2.5 J cm(-2) does not result in significantly different visual skin damage. The PDT response, however, is significantly reduced if the fluence is lowered to 1 J cm(-2), but this illumination scheme (1 + 99 J cm(-2)) remains significantly more effective than a single illumination of 100 J cm(-2). A first light fraction of 10 J cm(-2) can be delivered 2 h earlier, 2 h after the application of ALA, without significant reduction in the PDT response compared with 5 + 95 J cm(-2) delivered 4 and 6 h after the application of ALA. The kinetics of PpIX fluorescence are consistent with those reported previously by us and do not explain the significant increase in PDT response with a two-fold illumination scheme. Histological sections of the illuminated volume showed a trend toward increasing extent and depth of necrosis for the two-fold illumination scheme in which the first light fraction is 5 J cm(-2), compared with a single illumination scheme.     

Six‐coordinate Co2+ with imidazole,NH3, and H2O ligands: Approaching spin crossover

Octahedral, six‐coordinate Co²⁺ can exist in two spin states: S = 3/2 and S = 1/2. The difference in energy between high spin (S = 3/2) and low spin (S = 1/2) is dependent on both the ligand mix and coordination stereochemistry. B3LYP calculations on combinations of neutral imidazole, NH₃, and H₂O ligands show that low‐spin isomers are stabilized by axial H₂O ligands and in structures that also include trans pairs of equatorial NH₃ and protonated imidazole ligands, spin crossover structures are predicted from spin state energy differences. Occupied Co d orbitals from the DFT calculations provide a means of estimating effective ligand strength for homoleptic and mixed ligand combinations. These calculations suggest that in a labile biological system, a spin crossover environment can be created. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

A new column system for isothermal gas chromatographic analysis of light gases (H2, O2, N2, CO,CH4, CO2, C2H4, C2H6 and C2H2) employing a column switch technique

Summary A new column system for the isothermal analysis of H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ and C₂H₂ is described. Higher hydrocarbons and water are backflushed from the system. The use of 13X molecular sieve in a relatively deactivated state shortens the elution times of the light components and improves peak shapes. Both factors enable quantitative analyses to be carried out satisfactorily at lower concentrations than would otherwise be possible. Analysis of all compounds listed can be carried out in eleven minutes. Sparingly activated 13X molecular sieve columns have proved to be very stable and rarely require reactivation.The method of column switching employed avoids the use of mechanical valves in the sample path and is suitable for automatic operation.

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Neue Trennsäulenkombination für die GC-Analyse von Gasen (H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆, C₂H₂) unter Anwendung einer nichtmechanischen Säulenschalttechnik

Zusammenfassung Eine neue Trennsäulenkombination zur isothermen Trennung von H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ und C₂H₂ wird beschrieben. Höhere Kohlenwasserstoffe und Wasser werden rückgespült. Durch Anwendung eines auf relativ niedriger Aktivitätsstufe betriebenen Molekularsiebs 13X wird die Elutionszeit der flüchtigen Komponenten verkürzt und deren Peakform verbessert. Beides erlaubt befriedigende quantitative Analysen im Bereich kleinerer Konzentrationen, als dies mit anderen Systemen möglich ist. Die Analyse eines Gemisches aller oben angeführten Komponenten ist innerhalb von 11 Minuten möglich. Mäßig aktivierte Trennsäulen mit Molekularsieb 13X erwiesen sich als sehr stabil, sie erfordern nur selten eine Reaktivierung. Die hier verwendete Säulenschalttechnik vermeidet die Anwendung mechanischer Umschaltsysteme im Probenweg und ist für eine automatische isotheme Arbeitsweise besonders geeignet.

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Une nouvelle combinaison de colonnes pour l'analyse à température constante, par chromatographie en phase gazeuse, de gaz légers (H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ et C₂H₂) employant un système de commutation de colonnes

Résumé On décrit une nouvelle combinaison de colonnes pour l'analyse à température constante des mélanges de H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ et C₂H₂. Les hydrocarbures à plus grand nombre de carbones et l'eau sont éliminés du système par contrebalayage. L'emploi de tamis moléculaire 13X dans un état de désactivation relativement élevé permet de réduire les temps d'élution des composants légers et de rendre la forme des pics plus favorable. Ces deux facteurs permettent d'effectuer des analyses quantitatives à des concentrations plus basses que celles possibles normalement. L'analyse de tous les composants cités peut être faite en 11 minutes. Les colonnes de Tamis moléculaire 13X à degré d'activation modéré sont très stables et leur réactivation n'est nécessaire qu'après une longue période d'emploi. La méthode de commutation employée pour les colonnes évite l'utilisation de vannes mécaniques sur le parcours de l'échantillon; elle est convenable pour le fonctionnement automatique.

     

Use of mobile phase 18-crown-6 to improve peak resolution between mono- and divalent metal and amine cations in ion chromatography

It is difficult to quantify NH4+ by ion chromatography in the presence of high concentrations of Na+ due to peak overlap. The Dionex IonPac CS15 column, which contains phosphonate, carboxylate, and 18-crown-6 functional groups, was originally developed to overcome this problem. We have found that the addition of 18-crown-6 to the eluent promotes improved peak resolution between Na+ and NH4+ even at concentrations as high as 60,000 to 1 using this column. Its use also improves the separation of alkali and alkaline earth metal and amine cations. Mobile phase 18-crown-6 increased the retention times of CH3NH3+, NH4+, and K+, and decreased the retention time of Sr2+. The retention times of Li+, Na+, Mg2+, Ca2+, (CH3)2NH2+, and (CH3)3NH+ were not affected. This method makes possible the direct analysis of ammonia from nitrogenase, the enzyme responsible for biological nitrogen fixation. The resolution of the NH4+ peak from the Na+ and Mg2+ peaks improved from zero resolution to values of 6.19 and 5.65, respectively. This technique considerably reduces the analysis time of NH4+ in the presence of high concentrations of Mg2+ and Na+ over traditional indophenol measurements.     

Alkyl modified anionic siloxanes as pseudostationary phases for electrokinetic chromatography. I. Synthesis and characterization

Anionic water soluble siloxane polymers have been synthesized and characterized for electrokinetic chromatography. Siloxane polymers are of interest in electrokinetic chromatography because of the wide variety of chemistries that can be developed based on these backbones, including much of the stationary phase chemistry developed in the last 30 years. The siloxanes in this study have a sulfonate functional group. The siloxanes have different length alkyl chains (C8, C12, C18) attached to the backbone in differing densities. The methylene selectivity generally increases with increasing alkyl chain length and with increasing alkyl chain density. The electrophoretic mobility appears to pass through a maximum as more alkyl chain is added to the siloxane backbone. The efficiency also would seem to pass through a maximum as more alkyl chain is added. The chemical selectivities of the siloxane polymers are very different from sodium dodecyl sulfate but are similar to each other.     

Continuous sample deposition from reversed-phase liquid chromatography to tracks on a matrix-assisted laser desorption/ionization precoated target for the analysis of protein digests

Peptide mass fingerprinting by matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS) is one of the standard high-throughput methods for protein identification today. Traditionally this method has been based on spotting peptide mixtures onto MALDI targets. While this method works well for more abundant proteins, low-abundance proteins mixed with high-abundance proteins tend to go undetected due to ion suppression effects, instrumental dynamic range limitations and chemical noise interference. We present an alternative approach where liquid chromatography (LC) effluent is continuously collected as linear tracks on a MALDI target. In this manner the chromatographic separation is spatially preserved on the target, which enables generation of off-line LC-MS and LC-MS/MS data by MALDI. LC-MALDI sample collection provides improved sensitivity and dynamic range, spatial resolution of peptides along the sample track, and permits peptide mass mapping of low-abundance proteins in mixtures containing high-abundance proteins. In this work, standard and ribosomal protein digests are resolved and captured using LC-MALDI sample collection and analyzed by MALDI-TOF-MS.     

Production of Organometallic Polymers by the Interfacial Technique. XXXII. Reaction Variables in the Synthesis of Oligomeric Tin Poly(cobalticinium Esters) and Thermal Properties of the Products

The synthesis of oligomeric tin poly(cobalticinium esters) is presented as a function of the particular reaction variables stirring rate, pH and amount of added base, mole ratio of reactants, concentration of reactants, and volume of organic phase. Factors which decrease the solubility of the stannane apparently act to increase the yield of polyester. The thermal characterization of I was carried out via DSC and TGA. The products generally exhibit endotherms below 150 to 200[ddot]C which may be related to T_g. Above 200[ddot]C, degradation occurs in air by an oxidative mode.     

Uncovering the Hidden Landscape of Tris(4-pyridyl) Ligands: Topological Complexity Derived from the Bridgehead

Supramolecular main group chemistry is a developing field which parallels the conventional domain of metallo-organic chemistry. Little explored building blocks in this area are main group metal-based ligands which have the appropriate donor symmetry to build desired molecular or extended arrangements. Tris(pyridyl) main group ligands (E(py)₃, E=main group metal) are potentially highly versatile building blocks since shifting the N-donor arms from the 2- to the 3-positions and 4-positions provides a very simple way of changing the ligand character from mononuclear/chelating to multidentate/metal-bridging. Here, the coordination behaviour of the first main group metal tris(4-pyridyl) ligands, E(4-py)₃ (E=Sb, Bi, Ph−Sn) is explored, as well as their ability to build metal-organic frameworks (MOFs). The complicated topology of these MOFs shows a marked influence on the counter anion and on the ability of the E(4-py)₃ ligands to switch coordination mode, depending on the steric and donor character of the bridgehead. This structure-directing influence of the bridgehead provides a potential building strategy for future molecular and MOF design in this area.     

Surface modification by graphene oxide:An efficient strategy to improve the performance of activated carbon based supercapacitors

An efficient and cost-effective strategy to modificate the surface of active carbon (AC), form a 3D-conductive network, and therefore improve the electrochemical performance of AC based supercapacitor was developed.     

Miniature Wet-Bulb Technique for Measuring Gas Concentrations in Condensing or Evaporating Systems

Abstract

An analysis is presented to show that a miniature wet-bulb/dry-bulb probe can provide easy, rapid, and accurate point measurements of noncondensable gas concentrations in condensing or evaporating systems. The probe consists of a liquid-soaked porous sphere as small as 0.5 mm in diameter with a fine-gauge thermocouple embedded at its center. Performance of the probe is shown to improve with decreasing wet-bulb size. Measurements of only the total pressure and point wet-bulb temperature are needed to determine the local gas concentration for most gas-vapor systems. The use of the technique in systems with steep concentration gradients is demonstrated by application to the well-studied problem of the gas-loaded two-phase thermosyphon. 195pt