Two-photon laser spectroscopy of the muonium 1S–2S transition

The 1² S _1/2(F=1)?2² S _1/2(F=1) energy interval in muonium has been investigated by Doppler-free two-photon laser spectroscopy. The transition was observed by uniquely identifying and counting the muons released after the photoionization of the 2S state by the same laser field. The measured transition frequency of 2455 528016(58)(43) MHz is in good agreement with QED calculations. The experiment can be interpreted as a test of the Lamb shift contributions at the 1% level. The method is also well suited for a precise determination of the mass of the positive muon in a muoniumhydrogen isotope shift measurement.     

Cooperative,Reversible Self‐Assembly of Covalently Pre‐Linked Proteins into Giant Fibrous Structures

We demonstrate a simple bioconjugate polymer system that undergoes reversible self‐assembling into extended fibrous structures, reminiscent of those observed in living systems. It is comprised of green fluorescent protein (GFP) molecules linked into linear oligomeric strands through click step growth polymerization with dialkyne poly(ethylene oxide) (PEO). Confocal microscopy, atomic force microscopy, and dynamic light scattering revealed that such strands form high persistence length fibers, with lengths reaching tens of micrometers, and uniform, sub‐100 nm widths. We ascribe this remarkable and robust form of self‐assembly to the cooperativity arising from the known tendency of GFP molecules to dimerize through localized hydrophobic patches and from their covalent pre‐linking with flexible PEO. Dissipative particle dynamics simulations of a coarse‐grained model of the system revealed its tendency to form elongated fibrous aggregates, suggesting the general nature of this mode of self‐assembly.     

ON A NEW CLASS OF ANALYTIC FUNCTION DERIVED BY A FRACTIONAL DIFFERENTIAL OPERATOR

Making use of the fractional differential operator, we impose and study a new class of analytic functions in the unit disk （type fractional differential equation）. The main object of this paper is to investigate inclusion relations, coefficient bound for this class. Moreover, we discuss some geometric properties of the fractional differential operator.     

Equivalence in anisotropic N.M.R. spectra: the spectrum of ethyl iodide in the nematic phase

It is shown how the composite particle technique, which has proved useful for the analysis of the spectra of molecules in the isotropic liquid phase, may also be applied, with slight modifications, to spectra observed in an anisotropic environment. As an example, the analysis of the spectrum of ethyl iodide in the nematic phase is described.     

Zwei einfache Luftb?der, um Substanzen in Glasr?hren unter Druck zu erhitzen

Ohne Zusammenfassung     

Reactions of ZrOCl2·8H2O with carboxylic acids and thionyl chloride: crystal and molecular structures of K4[Zr(mal)4]·2H2O and K4[Zr(dipic)3]2·13.5H2O

Reactions of ZrOCl₂·8H₂O in aqueous solution with a carboxylic acid in the presence of K₂CO₃ have been studied as a route to Zr^IV-carboxylates. With malonic acid (HO₂CCH₂CO₂H) (H₂mal) the product has been identified as K₄[Zr(mal)₄]·2H₂O (1) by X-ray crystallography. The individual eight-coordinate zirconium anions contain four bidentate (OO) malonate anions with the metal geometry approximating to a square antiprism with each chelating ligand spanning the two square faces, Zr—O 2.091(3)–2.288(3) Å. The four potassium cations feature irregular coordination spheres of oxygen atoms [from both H₂O and (mal) ligand molecules] with a 7–9 coordination range. With 2,6-dicarboxypicolinicacid (HO₂CC₅NH₃CO₂H) (H₂dipic) the product has been characterised as K₄[Zr(dipic)₃]₂·13.5H₂O (2) following X-ray diffraction studies. The structure consists of two [Zr(dipic)₃]^2- anions, four potassium cations and lattice solvate (H₂O) molecules. Individual anions feature nine-coordinate zirconium in which each dipic ligand is terdentate, being bonded via one N (pyridine) and two O (carboxylate) atoms. The metal geometry approximates to tricapped trigonal prismatic with each nitrogen atom capping a regular face of four oxygen atoms, Zr—O, 2.216(6)–2.261(6) Å; Zr—N, 2.343(8)–2.361(7) Å. The potassium cations show similar environments to those observed in structure (1). Dehydration of ZrOCl₂·8H₂O using SOCl₂ in the presence of an excess of THF effects removal of coordinated H₂O molecules and hydroxy bridging groups to provide the anhydrous bis-adduct ZrCl₄(thf)₂ in good yield (72%).     

Comprehensive two-dimensional gas chromatography, retention indices and time-of-flight mass spectra of flavonoids and chalcones

The applicability of comprehensive two-dimensional gas chromatography (GC×GC) for flavonoids analysis was investigated by separation and identification of flavonoids in standards, and a complex matrix natural sample. The modulation temperature was optimized to achieve the best separation and signal enhancement. The separation pattern of trimethylsilyl (TMS) derivatives of flavonoids was compared on two complementary column sets. Whilst the BPX5/BPX50 (NP/P) column set offers better overall separation, BPX50/BPX5 (P/NP) provides better peak shape and sensitivity. Comparison of the identification power of GC×GC-TOFMS against both the NIST05 MS library and a laboratory (created in-house) TOFMS library was carried out on a flavonoid mixture. The basic retention index information on high-performance capillary columns with a non-polar stationary phase was established and database of mass spectra of trimethylsilyl derivatives of flavonoids was compiled. TOFMS coupled to GC×GC enabled satisfactory identification of flavonoids in complex matrix samples at their LOD over a range of 0.5-10 μg/mL. Detection of all compounds was based on full-scan mass spectra and for each compound a characteristic ion was chosen for further quantification. This study shows that GC×GC-TOFMS yields high specificity for flavonoids derived from real natural samples, dark chocolate, propolis, and chrysanthemum.