REVERSIBLE PHOTODIMERIZATION OF ANTHRACENE AND TETRACENE

Abstract— Dianthracene is efficiently photodissociated, forming anthracene with a quantum yield of about 0.63. Like anthracene, tetracene undergoes a reversible photochemical reaction, the product of which appears to be di-tetracene. In dilute, deoxygenated solutions the of quantum yeild for the formation of di-tetracene is directly proportional to the concentration of the monomer ødim = 2.2 (). The quantum yield for the reverse reaction is approximately 0.74
When dilute deaerated solutions of anthracene are irradiated with the unfiltered radiation from a quartz-mercury arc, a degradation product is formed. Unlike the dimer, this product cannot be converted into anthracene either by heating it to 200C or by irradiating it in solution with light of 254 nm. This degradation product appears to be the compound or compounds which Birks et al. believed to be dianthracene. Irradiation of deaerated solutions of anthracene (or tetracene) with light of wavelenghts longer than 300 nm produces only the dimer, which has an absorption spectrum similar to that reported by Coulson et al.     

Synthetic biohybrid peptidoglycan oligomers enable pan-bacteria-specific labeling and imaging: in vitro and in vivo

Peptidoglycan is the core component of the bacterial cell wall, which makes it an attractive target for the development of bacterial targeting agents. Intercepting its enzymatic assembly with synthetic substrates allows for labeling and engineering of live bacterial cells. Over the past two decades, small-molecule-based labeling agents, such as antibiotics, d-amino acids or monosaccharides have been developed for probing biological processes in bacteria. Herein, peptidoglycan oligomers, substrates for transglycosylation, are prepared for the first time using a top-down approach, which starts from chitosan as a cheap feedstock. A high efficiency of labeling has been observed in all bacterial strains tested using micromolar substrates. In contrast, uptake into mammalian cells was barely observable. Additional mechanistic studies support a hypothesis of bacteria-specific metabolic labeling rather than non-specific binding to the bacterial surface. Eventually, its practicality in bacterial targeting capability is demonstrated in resistant strain detection and in vivo infection models.

Peptidoglycan oligomers have been derived from chitosan, using a top-down bio-hybrid strategy, as highly bacteria-specific substrates.     

Rapid quantification of levosulpiride in human plasma using RP‐HPLC‐MS/MS for pharmacokinetic and bioequivalence study

A rapid and validated method for analysis of levosulpiride in human plasma using liquid chromatography coupled to tandem mass spectrometry was developed. Levosulpiride and tiapride (IS, internal standard) were extracted from alkalized plasma samples with ethylacetate and separation by RP‐HPLC. Detection was performed by positive ion electrospray ionization in multiple‐reaction monitoring mode, monitoring the transitions m/z 342.1 → m/z 112.2 and m/z 329.1 → m/z 213.2, for quantification of levosulpiride and IS, respectively. The standard calibration curves showed good linearity within the range of 2–200 ng/mL (r² ≥ 0.9990). The lower limit of quantitation was 2 ng/mL. The retention times of levosulpiride (0.63 min) and IS (0.66 min) presented a significant time saving benefit of the proposed method. No significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence study of a 25 mg of levosulpiride tablet in 24 healthy Korean volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

Photochromism of indoline spiropyrans of the coumarin series in polymeric matrices

The photochromic properties and aggregation processes of merocyanine forms of indoline spiropyrans of the coumarin series in the block and film poly(methyl methacrylate) (PMMA) were studied and compared by spectral and kinetic methods. Photochromism of the synthesized compounds depends on their structure. The efficient formation of J-aggregates was observed for indoline spiropyrans of the coumarin series based on 8-formyl-7-hydroxy-4-methylcoumarin and 3-formyl-4-hydroxycoumarin. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 870–875, May, 2007.     

Catalytic autooxidation ofp-anisaldehyde and styrene by a cobaltbis-schiff base complex

Summary The Co^II complex derived from the unsymmetricalbis-Schiff base ligand, 3-[1-[[2-[[(2-hydroxyphenyl)methylene]-amino]ethyl]amino]ethylidene]-6-methyl-2H-pyran-2,4(3H) dione H₂(dha, salen), is a catalyst for the autoxidation of aromatic aldehydes. Under ambient condition Co(dha, salen) catalyses the oxidation ofp-anisaldehyde top-anisic acid in quantitative yield (250 turnovers). The presence of Co(dha, salen) also accelerates the co-oxidation ofp-anisaldehyde and styrene (88 turnovers). In the co-oxidation process, styrene is selectively converted to styrene oxide as the major product.     

The Permutation Modules for GL(n+1, Fq) Acting on Pn(Fq) and Formula

The paper studies the permutation representations of a finitegeneral linear group, first on finite projective space and thenon the set of vectors of its standard module. In both casesthe submodule lattices of the permutation modules are determined.In the case of projective space, the result leads to the solutionof certain incidence problems in finite projective geometry,generalizing the rank formula of Hamada. In the other case,the results yield as a corollary the submodule structure ofcertain symmetric powers of the standard module for the finitegeneral linear group, from which one obtains the submodule structureof all symmetric powers of the standard module of the ambientalgebraic group.     

Approximate solution of boundary layer problems with injection or suction

Zusammenfassung Der grundlegende linearisierte Ansatz zur Näherungslösung von Grenzschichtproblemen wird auf neue Anwendungen erweitert, um die Behandlung von Problemen mit Massenaustausch durch die Oberfläche zu ermöglichen und die Beschränkung auf die Prandtl-Zahl 1 zu mildern. Das klassische Problem der konstanten, d. h. nicht ähnlichen Geschwindigkeitsverteilung an der Oberfläche wird behandelt, und die Ergebnisse werden mit der exakten numerischen Lösung verglichen. Es ergibt sich eine ausgezeichnete Übereinstimmung. Sodann wird eine Lösung des schwierigen und praktisch wichtigen Problems einer Stufenfunktion für die Oberflächengeschwindigkeit gegeben. Die freie Konvektion über einer vertikalen Platte mit konstanter Temperatur und Oberflächengeschwindigkeit wird erstmalig gelöst. Schliesslich wird das der Schlitzeinspritzung entsprechende Anfangswertproblem unter Milderung der bisherigen AnnahmeP _r =1 behandelt.

---

---

This work was supported by the National Science Foundation, Grant No. GK-310,