Electrospray ionization mass spectrometric study of purine base-cisplatin complexes

By mixing cisplatin (cis-diamminedichloroplatinum(II)) with purine base the following ions have been obtained under electrospray ionization conditions: [A+Pt(NH3)2 Cl]+, [A+PtNH3Cl]+, [G+Pt(NH3)2 Cl]+ and [G+PtNH3)Cl]+. Their collision-induced dissociation led to the loss of NH3 and HCl and formation of the protonated base. The last process is strongly favoured for adenine over guanine. It confirms that, analogously as for DNA, formation of the guanine-cisplatin complex is favoured over that of the adenine complex and, as a consequence, it suggests that the mass spectrometric study of nucleic base complexes with platinum may provide some information on the interactions of DNA with other platinum drugs. The loss of NH3 accompanied by that of CO from the guanine ring has experimentally confirmed the presence of a strong hydrogen bond between the NH3 molecule and the O=C6 moiety of guanine found by theoretical calculations.     

Measurement of the flux of ultrahigh energy cosmic rays from monocular observations by the High Resolution Fly's Eye experiment

We have measured the cosmic ray spectrum above 10(17.2) eV using the two air-fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, phototube, and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and extragalactic sources.     

Significance of sample dimensions and other parameters for characterizing drawing process of polymer films

Summary Uniaxial drawing of polymer samples by tensile testing, machines usually is characterized by drawing temperature, velocity and ratio. These data in general do not succeed in describing the drawing process completely, therefore different and/or additional parameters are necessary for characterization of drawing process.Striplike specimens of polyamide 6 and polyethylene terephthalate films were cut and drawn to a constant draw ratio. Especially sample dimensions, drawing velocity, drawing temperature and ambient medium were varied. Local draw ratio, birefringence and yield stresses were investigated.

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Zusammenfassung Die Herstellung uniaxial verstreckter Proben mit Hilfe einer Zugpriifmaschine wird üblicherweise durch Angabe von Verstrecktemperatur, relativer Verstreckgeschwindigkeit und Verstreckgrad beschrieben. Es wird gezeigt, dag diese Angaben i. a. nicht ausreichen, um den Verstreckvorgang zu beschreiben, dag hingegen andere und/oder zusätzliche Verstreckparameter eine vollständige Charakterisierung des Verstreckprozesses eher ermöglichen. Hierzu werden aus Polyamid- und Polyäthylenterephthalat-Folien geschnittene Polymerbänder unter Variation von Probendimensionen, absoluter Verstreckgeschwindigkeit, Verstrecktemperatur und Umgebungsmedium uniaxial auf den gleichen relativen Verstreckgrad gedehnt und auf ihre lokale Dehnung und ihre Doppelbrechung hin untersucht.

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With 11 figures and 1 table     

The structure of chaetoglobosin K.

The structure of chaetoglobosin K, a toxic metabolite from Diplodia macrospora, has been determined by single crystal X-ray analysis.     

Production and properties of polyacenaphthylene

Summary To produce standards for GPC calibration, oligomers of polyacenaphthylene were fractionated by the method of repeated sample injection in an analytical GPC unit (-styragel-columns, eluent THF). It is possible to separate about 2 g polymers in 24 hours into fractions with good uniformity.First communication: Jürgen Springer, Tin Win, Die Darstellung von Oligoacenaphthylenen mit funktionellen Endgruppen, Makromol. Chem.179, 29 (1978).     

Deconvolution of compartmental water diffusion coefficients in yeast-cell suspensions using combined T(1) and diffusion measurements

An NMR method is presented for measuring compartment-specific water diffusion coefficient (D) values. It uses relaxography, employing an extracellular contrast reagent (CR) to distinguish intracellular (IC) and extracellular (EC) (1)H(2)O signals by differences in their respective longitudinal (T(1)) relaxation times. A diffusion-weighted inversion-recovery spin-echo (DW-IRSE) pulse sequence was used to acquire IR data sets with systematically and independently varying inversion time (TI) and diffusion-attenuation gradient amplitude (g) values. Implementation of the DW-IRSE technique was demonstrated and validated using yeast cells suspended in 3 mM Gd-DTPA(2-) with a wet/dry mass ratio of 3.25:1.0. Two-dimensional (2D) NMR data were acquired at 2.0 T and analyzed using numerical inverse Laplace transformation (2D- and sequential 1D-ILT) and sequential exponential fitting to yield T(1) and water D values. All three methods gave substantial agreement. Exponential fitting, deemed the most accurate and time efficient, yielded T(1):D (relative contribution) values of 304 ms:0.023x10(-5) cm(2)/s (47%) and 65 ms:1.24x10(-5) cm(2)/s (53%) for the IC and EC components, respectively. The compartment-specific D values derived from direct biexponential fitting of diffusion-attenuation data were also in good agreement. Extension of the DW-IRSE method to in vivo models should provide valuable insights into compartment-specific water D changes in response to injury or disease. (c) 2002 Elsevier Science (USA).     

Heating of thin foils with a relativistic-intensity short-pulse laser

K-shell x-ray spectroscopy of sub-100 nm Al foils irradiated by high contrast, spatially uniform, 150 fs, Ilambda (2)=2 x 10(18) W microm(2)/cm(2), laser pulses is obtained with 500 fs time resolution. Two distinct phases occur: At /=500 fs the resonance transitions dominate. Initial satellites arise from a large area, high density, low temperature (approximately 100 eV) plasma created by fast electrons. Thus, contrary to predictions, a short, high intensity laser incident on a thin foil does not create a uniform, hot dense plasma.