•The improved thermal desorption diagnostics have been developed and tested in the Uragan-2M stellarator.•Using this diagnostics and mass-spectrometric method it was shown that hydrogen can be the ...one of the main gases which desorbs at the temperature of 250-300°C after discharge cleaning in hydrogen atmosphere.•Glow discharge cleaning with Ar plasma leads to Ar noticeable desorption from the stainless steel. Two kinds of desorbed Ar were registered with two different thermal desorption activation energies.
The improved thermal desorption diagnostics has been manufactured, installed and tested in the Uragan-2M (U-2M) stellarator 1-5 for in-situ characterisation a stainless steel (SS) wall outgassing rate and a number of molecular layers of residual gases on its surface in four different positions. The detailed description of this diagnostics, the location of thermal desorption stainless steel probes, the methodology of determining the outgassing rates and the number of molecular layers of residual gases on the probe surfaces are presented. It has been found that the difference between of the data taken from the probes being at different position in the U-2M vacuum chamber lies within the measurement accuracy. Using the present diagnostics together with the mass-spectrometer measurements, some studies were made to investigate the release of gases from the thermal desorption probes before and after radio frequency (RF) or glow discharge (GD) cleaning with hydrogen, helium and argon plasmas. It has been observed that hydrogen sorption by the SS probes surface during the discharge cleaning leads to significant hydrogen desorption even at the temperature of 250-300°C. In this case, hydrogen can be the one of the main gases which desorbs. After U-2M glow discharge cleaning with Ar plasma, the thermal desorption experiment has shown Ar as a significant component which is desorbed from the SS probe surface. Two kinds of desorbed Ar were registered with two different activation energies. The characteristics of the U-2M vacuum system are presented, too, including the block scheme, the list of pumps used to attain the ultimate vacuum, the equipment for measuring the total and partial pressures of residual gases.
—
We have studied phase equilibria in the silicon-rich part of the Yb–Pt–Si system. To this end, 22 alloys were prepared by a standard arc-melting process in an argon atmosphere and annealed at a ...temperature of 850°C. Physicochemical characterization of the samples included electron microscopy, X-ray microanalysis, X-ray diffraction, and differential thermal analysis. We have confirmed the existence of four previously known intermetallic compounds: YbPtSi, YbPt
2
Si
2
, Yb
3
Pt
4
Si
6
, and Yb
2
Pt
3
Si
5
. In addition, three new phases have been identified: YbPtSi
2
, Yb
33
Pt
17
Si
50
, and Yb
11
Pt
33
Si
56
. The structure type of the YbPtSi
2
compound has been determined. We present statistical crystallographic data for the ternary phases and describe phase equilibria in the region studied in the 850°C isothermal section of the Yb–Pt–Si phase diagram.
A general method of the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by Suzuki-Miyaura cross-coupling from 4- and 5-halo-1,2,3-triazoles is reported. The reaction is mediated by an expanded-ring ...N-heterocyclic carbene palladium complex in water. The developed reaction protocol meets the requirements of "green chemistry". Cross-coupling of 4- and 5-chlorotriazoles is reported for the first time.
Objective — The goal of our study was to establish the relationship between the postural balance and heart rate variability (HRV) in elderly women with the falls syndrome. Material and Methods — The ...study was conducted on120 women aged 60-74 YO. The study group included women with the falls syndrome who experienced two or more falls during the year (n=60), while the comparison group consisted of women without falls (n=60). Postural balance assessment was performed via the computerized stabilometric complex Balance Master®, NeuroCom, Natus Medical, USA. The state of autonomic nervous system was assessed by cardiointervalography using the VNS-Spectrum computer appliance (Neurosoft, Russia). Results — The matrix of intersystem correlations between indicators of postural balance and HRV in women with the falls syndrome was characterized by a small number of statistically significant correlations (6.25%). Same was true for the control group (10.85%). The correlations were noted in the Sit to Stand, Tandem Walk, and Step Up and Over tests in elderly women with the falls syndrome, while in the control group, they were observed only in the Step Quick Turn test. Conclusion — Features of the relationship between postural balance indicators and HRV in elderly women with the falls syndrome were characterized by a worse coordination of intersystem interactions of HRV indicators with indicators of the performance quality of complex motor acts and power indicators of postural balance, as compared with the elderly women without falls syndrome.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
45.
Wooden beams with local wood modification Gribanov, A S; Roshchina, S I; Naichuk, A Ya ...
IOP conference series. Materials Science and Engineering,
07/2020, Letnik:
896, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The purpose of this work is to study the strength of wooden beam structures with local modification of wood in the compressed zone. To achieve this goal, the physical and mechanical characteristics ...of modified wood were determined using modifiers based on ed-20 epoxy-diane resin, urea-formaldehyde resin, and dimethacrylic polyester. The best physical and mechanical characteristics were obtained for samples using dimethacrylic polyester: the ultimate strength was 84 MPa, the elastic modulus was 21 GPa. The increase in strength compared to solid wood was 46%, and the increase in the modulus of elasticity was 54%. Tests of beam structures with a span of 4.5 m and a cross section of 100x200 mm with local modification of wood in the compressed zone with a polymer composition based on dimethacrylic polyester were carried out. The increase in the strength of beams with local modification in the compressed zone compared to solid wood was 11% within the design loads, and the increase in stiffness by 18%. The "load-strain" relationships are constructed based on the test results. It is established that the greatest effect can be achieved when using external reinforcement systems together in a stretched zone by reducing the influence of defects and defects in beam structures and local modification of the extremely stressed compressed zone.
Lake Baikal, the world's most voluminous freshwater lake, has experienced unprecedented warming during the last decades. A uniquely diverse amphipod fauna inhabits the littoral zone and can serve as ...a model system to identify the role of thermal tolerance under climate change. This study aimed to identify sublethal thermal constraints in two of the most abundant endemic Baikal amphipods, Eulimnogammarus verrucosus and Eulimnogammarus cyaneus, and Gammarus lacustris, a ubiquitous gammarid of the Holarctic. As the latter is only found in some shallow isolated bays of the lake, we further addressed the question whether rising temperatures could promote the widespread invasion of this non‐endemic species into the littoral zone. Animals were exposed to gradual temperature increases (4 week, 0.8 °C/d; 24 h, 1 °C/h) starting from the reported annual mean temperature of the Baikal littoral (6 °C). Within the framework of oxygen‐ and capacity‐limited thermal tolerance (OCLTT), we used a nonlinear regression approach to determine the points at which the changing temperature‐dependence of relevant physiological processes indicates the onset of limitation. Limitations in ventilation representing the first limits of thermal tolerance (pejus (= “getting worse”) temperatures (Tp)) were recorded at 10.6 (95% confidence interval; 9.5, 11.7), 19.1 (17.9, 20.2), and 21.1 (19.8, 22.4) °C in E. verrucosus, E. cyaneus, and G. lacustris, respectively. Field observations revealed that E. verrucosus retreated from the upper littoral to deeper and cooler waters once its Tp was surpassed, identifying Tp as the ecological thermal boundary. Constraints in oxygen consumption at higher than critical temperatures (Tc) led to an exponential increase in mortality in all species. Exposure to short‐term warming resulted in higher threshold values, consistent with a time dependence of thermal tolerance. In conclusion, species‐specific limits to oxygen supply capacity are likely key in the onset of constraining (beyond pejus) and then life‐threatening (beyond critical) conditions. Ecological consequences of these limits are mediated through behavioral plasticity in E. verrucosus. However, similar upper thermal limits in E. cyaneus (endemic, Baikal) and G. lacustris (ubiquitous, Holarctic) indicate that the potential invader G. lacustris would not necessarily benefit from rising temperatures. Secondary effects of increasing temperatures remain to be investigated.
(THD‐Dipp)AuOTf, supported by the strongly electron donating, sterically bulky THD‐Dipp (1,3‐bis(2,6‐diisopropylphenyl)hexahydro‐2H‐1,3‐diazepine‐2‐ylidene) seven‐membered N‐heterocyclic carbene ...ligand, efficiently promotes intermolecular addition of Ts‐ and Boc‐hydrazine to arylalkynes under solvent‐free conditions.
Let
A
be an
(
m
×
n
)
integral matrix, and let
P
=
{
x
:
A
x
≤
b
}
be an
n
-dimensional polytope. The width of
P
is defined as
w
(
P
)
=
m
i
n
{
x
∈
Z
n
\
{
0
}
:
m
a
x
x
∈
P
x
⊤
u
-
m
i
n
x
∈
P
x
⊤
...v
}
. Let
Δ
(
A
)
and
δ
(
A
)
denote the greatest and the smallest absolute values of a determinant among all
r
(
A
)
×
r
(
A
)
sub-matrices of
A
, where
r
(
A
) is the rank of the matrix
A
. We prove that if every
r
(
A
)
×
r
(
A
)
sub-matrix of
A
has a determinant equal to
±
Δ
(
A
)
or 0 and
w
(
P
)
≥
(
Δ
(
A
)
-
1
)
(
n
+
1
)
, then
P
contains
n
affine independent integer points. Additionally, we present similar results for the case of
k-modular
matrices. The matrix
A
is called
totally
k
-modular if every square sub-matrix of
A
has a determinant in the set
{
0
,
±
k
r
:
r
∈
N
}
. When
P
is a simplex and
w
(
P
)
≥
δ
(
A
)
-
1
, we describe a polynomial time algorithm for finding an integer point in
P
.
A
bstract
The cross section of the process
e
+
e
−
→ ηπ
+
π
−
is measured using the data collected with the CMD-3 detector at the VEPP-2000 collider in the center-of-mass energy range from 1
.
1 to 2
....
0 GeV. The decay mode
η → γγ
is used for
η
meson reconstruction in the data sample corresponding to an integrated luminosity of 78
.
3 pb
−
1
. The energy dependence of the
e
+
e
−
→ ηπ
+
π
−
cross section is fitted within the framework of vector meson dominance in order to extract the Γ(
ρ
(1450)
→ e
+
e
−
)
B
(
ρ
(1450)
→ ηπ
+
π
−
) and the Γ(
ρ
(1700)
→ e
+
e
−
)
B
(
ρ
(1700)
→ ηπ
+
π
−
) products. Based on conservation of vector current, the analyzed data are used to test the relationship between the
e
+
e
−
→ ηπ
+
π
−
cross section and the spectral function in
τ
−
→ ηπ
−
π
0
ντ
decay. The
e
+
e
−
→ ηπ
+
π
−
cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.
The process e+e−→K+K− has been studied using 1.7×106 events from a data sample corresponding to an integrated luminosity of 5.7 pb−1 collected with the CMD-3 detector in the center-of-mass energy ...range 1010–1060 MeV. The cross section is measured with about 2% systematic uncertainty and is used to calculate the contribution to the anomalous magnetic moment of the muon aμK+K−=(19.33±0.40)×10−10, and to obtain the ϕ(1020) meson parameters. We consider the relationship between the e+e−→K+K− and e+e−→KS0KL0 cross sections and compare it to the theoretical prediction.
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