We synthesized 1-ethylimidazolyl-substituted nitronyl nitroxides,
i.e.
, 2-(1-ethylimidazol-4-yl)- (L
4Et
) and 2-(1-ethylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1
H
-imidazole 3-oxide-1-oxyl ...(L
5Et
). The stable radical L
5Et
is an ethyl analog of 2-(1-methylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1
H
-imidazole 3-oxide-1-oxyl (L
5Me
) described earlier, the reaction of which with Cu(hfac)
2
(hfac is 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) leads to the formation of the Cu(hfac)
2
(L
5Me
)
2
jumping crystals. The reaction of Cu(hfac)
2
with L
5Et
with reagent ratios 1: 2 and 1: 1 yields heterospin complexes Cu(hfac)
2
(L
5Et
)
2
and Cu(hfac)
2
L
5Et
2
, respectively. X-ray diffraction study of the mononuclear complex Cu(hfac)
2
(L
5Et
)
2
determined that the compound has a packing similar to that of jumping crystals studied earlier, with the only difference being that the O...O contacts between neigh- boring nitroxide groups were found to be 0.3—0.5 Å longer than in Cu(hfac)
2
(L
5Me
)
2
. As a result of the lengthening of these contacts, Cu(hfac)
2
(L
5Et
)
2
crystals lack chemomechanical activi- ty. We found that when cooling crystals of binuclear complex Cu(hfac)
2
L
5Et
2
below 50 K, the antiferromagnetic exchange between unpaired electrons of the >N—•O groups of neighboring molecules leads to the full spin-pairing of the nitroxides, with only the Cu
2+
ions contributing to the residual paramagnetism of the compound.
A “porous glass + indium” nanocomposite has been prepared. The thermal conductivity κ(
T
) and electrical resistivity ρ(
T
) of the nanocomposite have been measured in the temperature range 5–300 K, ...and their fractions accounted for by nanoindium embedded in 7-nm channels of the porous glass have been determined. For comparison, κ and ρ of the bulk polycrystalline indium sample have been measured in the same temperature range. The electronic and phonon components of the thermal conductivity have been calculated for the nanoindium and bulk indium. It has been demonstrated that, as the result of the emergence of boundary electron and phonon scattering in the nanoindium, the electrical resistivity of this material becomes larger, and the phonon thermal conductivity, smaller than those of the bulk indium.
A nanocomposite chrysotile-KDP (KH
2
PO
4
) was prepared. KDP was introduced into empty nanochannels of chrysotile asbestos with diameters of ∼5 nm. Thermal conductivity κ and heat capacity at a ...constant pressure
C
p
of the samples of chrysotile asbestos and nanocomposite chrysotile asbestos-KDP were measured in a temperature range of 80–300 K. Based on the analysis of the behavior of temperature dependences κ(
T
) and
C
p
(
T
) of the composite, temperatures of the ferroelectric transition
T
F
for KDP in nanochannels of chrysotile asbestos were determined. It turned out to be equal to ∼250 K at
T
F
∼ 122 K for massive KDP samples.
Huisgen's 1,3-dipolar cycloadditions become nonconcerted when copper(I) acetylides react with azides and nitrile oxides, providing ready access to 1,4-disubstituted 1,2,3-triazoles and ...3,4-disubstituted isoxazoles, respectively. The process is highly reliable and exhibits an unusually wide scope with respect to both components. Computational studies revealed a stepwise mechanism involving unprecedented metallacycle intermediates, which appear to be common for a variety of dipoles.
The PHENIX Electromagnetic Calorimeter (EMCal) is used to measure the spatial position and energy of electrons and photons produced in heavy ion collisions. It covers the full central spectrometer ...acceptance of 70°⩽
θ⩽110° with two walls, each subtending 90° in azimuth. One wall comprises four sectors of a Pb-scintillator sampling calorimeter and the other has two sectors of Pb-scintillator and two of a Pb-glass Cherenkov calorimeter. Both detectors have very good energy, spatial and timing resolution, while the Pb-scintillator excels in timing and the Pb-glass in energy measurements. Also, having two detectors with different systematics increases the confidence level of the physics results. Design and operational parameters of the Pb-scintillator, Pb-glass and special readout electronics for EMCal are presented and running experience during the first year of data taking with PHENIX is discussed. Some examples of data taken during the first run are shown.
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