Photolithographic production of glass sample holders for improved sensitivity and resolution in ESR microscopy

Electron spin resonance microscopy (ESRM) is an imaging method aiming at the observation of stable free radicals in small samples with a spatial resolution of about 1 micrometer. One of the challenges associated with the useof ESRM in conjunction with small biological samples (e.g., single cells) is containing these samples in a manner that will minimize the effect on the quality factor of the resonator but yet enable easy handling and simultaneous optical and ESR observation. Here we present a new type of flat samples that provide an adequate answer to this challenge. The samples are made of thin glass coverslips, manufactured by photolithography techniques. Details of the manufacturing process as well as the expected improvements in sensitivity and resolution are provided.     

Determination of Arsenic with Michler's Thioketone

Michler's thioketone is proposed as the reagent for the spectrophotometric determination of trace arsenic(V). The molar absorptivity of the colored product of interaction between Michler's thioketone and molybdoarsenic acid is (1.02 ± 0.04) × 10⁵at 640 nm. A procedure is developed for the extraction–photometric determination of arsenic in tap and mineral waters. The added–found method is used. The determination limit of arsenic is 0.003 mg/L; in the concentration range 0.008–0.12 mg/L, the relative standard deviation varies from 20 to 8 %.     

Thermodynamic properties of some polymeric forms of fullerite C<Subscript>60</Subscript> at temperatures ranging from 0 to 320 K

The temperature dependences of the heat capacityC ⁰ _p of fullerites C₆₀ were studied at temperatures ranging from 5 to 320 K in an adiabatic vacuum calorimeter with an accuracy of 0.4–0.2%. The fullerite C₆₀ samples were prepared by treating the starting fullerite C₆₀ under 8 GPa at 920 and 1270 K and “quenched” by a sharp decrease in pressure to −10⁵ Pa and in temperature to ∼300 K. Fullerite C₆₀(8 GPa, 920 K), a crystalline polymer with layered structure formed by polymerized fullerene C₆₀ molecules, was obtained at 920 K and 8 GPa. Fullerite C₆₀(8 GPa, 1270 K), a three-dimensional polymer with a graphite-like structure formed by fragments of decomposed C₆₀ molecules and containing many C(sp³)−C(sp³) bonds, was obtained at 1270 K and 8 GPa. Both polymers are metastable polymeric phases. The anomalous character of the temperature dependence of the heat capacity was revealed in the 49–66 K range for the polymer formed at 1270 K. The thermodynamic functions of the substances under study were calculated for the 0–320 K region along with entropies of their formation from graphite. The entropies of transformation of the starting fullerite C₆₀ into metastable phases and that of intertransformation of phases were estimated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 277–281, February, 2000.     

Refraction and ultra‐small‐angle scattering of X‐rays in a single‐crystal diamond compound refractive lens

In this work a double‐crystal setup is employed to study compound refractive lenses made of single‐crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra‐small‐angle broadening of the X‐ray beam. It is shown that, similarly to the wavefront aberrations, the ultra‐small‐angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X‐ray lenses composed of many tens of unit lenses.     

Experimental demonstration of a W-band (94 GHz) gyrotwystronamplifier

A four section, TE₀₁ mode W-band gyrotwystron amplifier has been designed, built, and tested. The circuit consists of three cavities followed by a traveling wave output section, each operating near the fundamental cyclotron frequency. The gyrotwystron has produced 50 kW peak output power, corresponding to 17.5% efficiency for a 57 kV, 5 A electron beam; the amplifier is zero drive stable at the operating point. The measured center frequency is 93.9 GHz with a full width half maximum instantaneous bandwidth of 925 MHz. These results represent a substantial improvement in the power-bandwidth product over previously demonstrated gyro amplifiers in this band. The small signal and saturated gains were 39 and 30 dB, respectively. The measured results are in good agreement with theoretical predictions     

Studies with one- and two-proton drip line nuclei

In recent experiments at GANIL, we studied nuclei at the one- and two-proton drip line. The production rates allowed to search for direct 2p emission in the drip line nuclei ⁴²Cr, ⁴⁵Fe, and ⁴⁹Ni. No evidence for this decay mode was found in ⁴²Cr and ⁴⁹Ni, whereas the situation stays unclear for ⁴⁵Fe due to the limited statistics. In the medium-mass region ( A = 50-70), the half-life was measured for all proton-rich nuclei in the range T _z = 0 to T _z = - 1 between Z = 27 and Z = 36. First half-lives were determined for ⁶⁰Ga, ⁶²Ge, ⁶⁴As and ⁶⁶Se. Finally, β-decay studies of the 0⁺ → 0⁺ decay of ⁶²Ga have been performed at IGISOL in Jyv?skyl?. Non-analog transitions have been observed and are compared to theoretical predictions. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: blank@cenbg.in2p3.fr     

Surfaces of transport in non-Euclidean spaces

This paper is a survey of results on the generalized Lie problem of surfaces carrying more than one net of transport and its connections with kinematic geometry.Translated from Itogi Nauki i Tekhniki. Problemy Geometrii, Vol. 8, pp. 183–196, 1977.