Thermal properties of more than 20 different polyureas intended for the use as protective varnish for printed-circuit boards have been studied. Rate and completeness of the polyureas decomposition as ...well as their solubility in common solvents have been analyzed. It has been shown that the polyureas synthesized from branched diisocyanates, for example, isophorone diisocyanate or 1,3-bis-(isocyanatomethyl)cyclohexane, and diamines (
N
,
N
′-dialkylethylene and propylenediamine) are prone to fast and complete decomposition at relatively low temperature. For instance, the polymer formed via the reaction between piperazine and isophorone diisocyanate has been completely decomposed at 400°C within 1 min, whereas degree of decomposition of the polymer obtained from piperazine and hexamethylene diisocyanate has been as low as 31% under the same conditions. The relationship between the completeness of the polyureas decomposition and the shape of their thermogravimetric analysis curves has been stated.
Experimental studies of elastic, anelastic, dielectric, polarization and thermal properties of sodium trihydrogen selenite NaN
3
(SeO
3
)
2
crystal in the temperature range of 5-210 K. Above the ...ferroelectric Curie temperature, an intermediate ferroelastic β′-phase was detected between the paraelectric α-phase and the ferroelectric β-phase. The phase transition from α- to β′-phase at 195 K is classified as a first-order transition, accompanied by the occurrence of spontaneous deformation x
6s
. When the temperature decreases, in addition to the previously known transition from the β-phase to the γ-phase, a new phase transition from the γ-phase to the nonpolar η-phase at a temperature of 112.4 K was detected.
The polarization observables T,E,P,H, and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W=2400 MeV (T), 2280 MeV (E), 1620 MeV (P,H), or 1820 MeV ...(G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JüBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33±0.04 for N(1650)1/2− is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass JP=1/2−-resonances significantly.
The low-frequency internal friction
Q
–1
and shear modulus
G
have been studied by the inverted torsion pendulum method for a series of crystals belonging to potassium dihydrogen phosphate family: KH
...2
PO
4
, KD
2
PO
4
, 0.95KH
2
PO
4
–0.05NH
4
H
2
PO
4
, RbH
2
PO
4
, RbH
2
AsO
4
, and CsH
2
AsO
4
. A number of anomalies have been revealed in the temperature dependences
Q
–1
(
T
) and
G
(
T
), both in the ferroelectric and paraelectric phases of these crystals; the nature of these anomalies is discussed.
K+Λ(1405) photoproduction has been studied at the BGOOD experiment via the all neutral decay, Λ(1405)→Σ0π0. The unique BGOOD experimental setup allows both the cross section and Λ(1405) invariant ...mass distribution (line shape) to be measured over a broad K+ polar angle range, extending to extreme forward K+ angles unattainable at previous experiments.
Evidence is provided for the role of a triangle singularity driven by the N⁎(2030) resonance, which appears to contribute significantly to K+Λ(1405) photoproduction. This is observed in the integrated cross section which was determined with unprecedented energy resolution and supported by the angular distributions. The measured line shape is also in agreement with the previous results of CLAS and ANKE, and is consistent with two poles derived in χPT based models.
The coherent reaction, γd→π0π0d was studied with the BGOOD experiment at ELSA from threshold to a centre-of-mass energy of 2850MeV. A full kinematic reconstruction was made, with final state ...deuterons identified in the forward spectrometer and π0 decays in the central BGO Rugby Ball. The strength of the differential cross section exceeds what can be described by models of coherent photoproduction and instead supports the three isoscalar dibaryon candidates reported by the ELPH collaboration at 2.38, 2.47 and 2.63GeV/c2. A low mass enhancement in the π0π0 invariant mass is also observed at the d⁎(2380) centre-of-mass energy which is consistent with the ABC effect. At higher centre-of-mass energies, a narrow peak in the π0d invariant mass at 2114MeV/c2 with a width of 20MeV/c2 supports a sequential two-dibaryon decay mechanism.
Nanocomposite thin films containing Pb(Zr
0.53
Ti
0.47
)O
3
(PZT) and Co or Ni are deposited on pyroceramic and silicon substrates by ion-beam sputtering. Structural characterizations show that only ...PZT and Co or Ni phases exist in the composite films, and the crystalline Co or Ni nanogranules with average sizes of 3.0-8.0 nm are randomly embedded in the amorphous PZT matrix. The conductivity and magnetoresistance mechanisms were studied as a function of composition, temperature and magnetic field. The crystallization and structure relaxation processes in amorphous PZT were observed, and results obtained are discussed.
Various styrene–methacrylate composites with mineral fillers have been studied as a substrate for the deposition of copper tracks on surfaces after laser ablation. It has been revealed that both ...insufficient laser heating of the substrate with applied varnish and its overheating have a negative effect on chemical copper plating. The use of crosslinked styrene–methacrylate polymers makes it possible to achieve stable copper plating of the laser-treated surface of the varnish-coated substrate. It has been shown that with an appropriate selection of ablation parameters, finely divided minerals, such as talc, celadonite, aquamarine, shungite, chromia, and iron oxide (ocher), can be used as varnish filler for chemical copper plating of laser-treated parts of the substrate.
The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium ...modifications of the omega meson via the reaction gamma + A --> omega + X --> pi(0)gamma + X('). Results obtained for Nb are compared to a reference measurement on a LH2 target. While for recoiling, long-lived mesons (pi(0), eta, and eta;(')), which decay outside of the nucleus, a difference in the line shape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons produced on the Nb target. For momenta less than 500 MeV/c an in-medium omega meson mass of M(medium) = 722(+4)(-4)(stat)+35-5(syst) MeV/c(2) has been deduced at an estimated average nuclear density of 0.6rho(0).
Abstract
The effect of different seeding rates, providing the density of 40, 60, and 80 thousand plants/ha, on the yield and its quality of the new sunflower hybrids of VNIIMK breeding (Immi, Arneb, ...Gorfild) was studied at the V.S. Pustovoit All-Russian Research Institute of Oil Crops (VNIIMK) (Krasnodar) in 2019-2020. The purpose of the research is to determine the effect of different seeding rates on the elements of plant productivity, yield, oil content of seeds, and oil yield of promising sunflower hybrids. The sunflower hybrid Arneb appeared to be the most stable in terms of productivity at different seeding rates. It has a high tolerance to its increase even under a water deficiency. Hybrids Immi and Gorfild are more susceptible to plant thickening. Their productivity is decreasing in unfavorable water conditions.
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