To meet new trigger and data acquisition (TDAQ) buffering requirements and withstand the high expected radiation doses at the High-Luminosity LHC, the ATLAS Liquid Argon Calorimeter readout ...electronics will be upgraded. The triangular calorimeter signals are amplified and shaped by analog electronics over a dynamic range of 16 bits, with low noise and excellent linearity. Developments of low-power preamplifiers and shapers in the 130 nm CMOS technology are ongoing to meet these requirements. In order to digitize the analog signals on two gains after shaping, a radiation-hard, low-power 40 MHz 14-bit Analog-to-Digital Converter (ADC) is developed using a pipeline + Successive Approximation Register (SAR) architecture in the 65 nm CMOS technology. Characterization of the prototypes of the front-end components show good promise to fulfill all the requirements. The signals will be sent at 40 MHz to the off detector electronics, where Field-Programmable Gate Arrays (FPGAs) connected through high-speed links will perform energy and time reconstruction through the application of corrections and digital filtering. Reduced data will be sent with low latency to the first level trigger, while the full data will be buffered until the reception of trigger accept signals. The data-processing, control and timing functions will be realized by dedicated boards connected through Advanced Telecommunications Computing Architecture (ATCA) crates.
The Prins/Friedel-Crafts cascade reactions of the terpenoid trans-4-hydroxymethyl-2-carene (synthesized from 3-carene) with aromatic aldehydes were systematically studied for the first time on acidic ...mesoporous clays (halloysite, illite, montmorillonites). Both the reaction rate and selectivity to the desired polycyclic product with tetrahydrofuran moiety increased with an increase in the catalyst acidity and their drying temperature, indicating that relatively strong Brønsted and Lewis acid sites favored their formation. The best activity and selectivity (up to 97%) was demonstrated over commercial montmorillonite K-10 with acidity of ca. 100 μmol/g. In contrast, on strongest acids (resin Amberlyst-15), dehydration/aromatization of the substrate was observed. It was shown, that mesoporosity of the catalyst is one of the key factors governing catalytic behavior. The presence of at least one an electron-donor substituent at the meta-position of benzaldehyde is critical for the Prins-Friedel-Crafts reaction. Overall, available montmorillonites are an effective replacement for homogeneous catalysts for the Prins/Friedel-Crafts cascade reactions.
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•Mesoporous clays as catalysts for cascade Prins/Friedel-Crafts reactions.•Montmorillonites are most effective ones.•Moderate acidity (100 μmol/g) provides high activity and selectivity.•The reaction mechanism was analyzed at the DFT level.•Mild reaction conditions and catalyst reusability.
A method of imaging of ultra-fast processes, like explosion or fast combustion, at a synchrotron radiation beam is being developed at the Siberian Synchrotron and Teraherz Radiation Center (SSTRC) . ...Two stations are operating at beam line 0 at the VEPP-3 storage ring and at beam line 8 at the VEPP-4M storage ring. Both stations are equipped with the detector for imaging of explosions DIMEX, based on high pressure ionization chamber, and allowing to record up to 100 one dimensional images with the frame rate of 8 MHz. However the maximum flux that DIMEX can detect is limited as well as spatial resolution and frame rate because of gas technology used. In view of significant increase of SR flux at the VEPP-4M beam line due to the new 9-pole 2 T wiggler, a new detector is being developed for this beam line, based on Si microstrip sensor. The first Si microstrip detector prototype has been mounted with new specially developed front-end ASIC that allows to record data with the rate of 50 MFrames/s. The first measurements with this prototype demonstrated significant improvement of all critical parameters of the detector compared to the gaseous version.
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•First systematic study of catalytic terpenoid diol condensation with an aldehydes to bioactive hexahydro-2H-chromene-4,8-diols.•Halloysite nanocatalyst increases both the yields of ...hexahydro-2H-chromene-4,8-diols and 4S/4R isomers ratio.•Inversion of stereoselectivity with increasing acidity or catalyst drying temperature.•The reaction mechanism is discussed with DFT calculations and kinetic modeling.
Condensation of α-pinene derived p-menta-1,8-diene-5,6-diol (diol) with decanal was studied for the first time over modified halloysite nanotubes (HNT). The yield of the desired hexahydro-2H-chromene-4,8-diol with analgesic activity was 76–80 % practically not depending on the catalyst type, while selectivity to 4S-isomer decreased, and to 4R-isomer increased with increasing acidity. The highest selectivity to 4S-diastereomer (48.1 %) on halloysite is a result of weak acidity of this catalyst. DFT optimization of the key intermediate structure shows that the nucleophile attack proceeds at the equatorial position with the 4S-diastereomer formation, which was preferred on halloysite. On strong Brønsted (Amberlyst-15) and Lewis (scandium triflate) acids the target product yield did not exceed 37 % because of dehydration. Halloysite nanocatalysts displayed a stable performance. In the case of diol reaction with a set of carbonyl compounds, the yields of hexahydro-2H-chromene-4,8-diols (up to 88.0%) and the ratio of its 4S/4R isomers (up to 21.0) were significantly higher than on other catalysts.
The process
e
+
e
-
→
n
n
¯
is studied in the experiment at the VEPP-2000
e
+
e
-
collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) electromagnetic ...calorimeter is used to select
n
n
¯
events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The process
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
-
...collider. The
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ϕ
η
intermediate state. Our result on the
e
+
e
-
→
η
η
γ
cross section is consistent with the
e
+
e
-
→
ϕ
η
measurement in the
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Two novel structural types of tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors with hexahydroisobenzofuran
and 3-oxabicyclo 3.3.1nonane
scaffolds were discovered. These monoterpene-derived compounds ...were synthesized through preliminary isomerization of (+)-3-carene to (+)-2-carene followed by reaction with heteroaromatic aldehydes. All the compounds inhibit the TDP1 enzyme at micro- and submicromolar levels, with the most potent compound having an IC
value of 0.65 μM. TDP1 is an important DNA repair enzyme and a promising target for the development of new chemosensitizing agents. A panel of isogenic clones of the HEK293FT cell line knockout for the
gene was created using the CRISPR-Cas9 system. Cytotoxic effects of topotecan (Tpc) and non-cytotoxic compounds of the new structures were investigated separately and jointly in the
gene knockout cells. For two TDP1 inhibitors,
and
, a synergistic effect was observed with Tpc in the HEK293FT cells but was not found in TDP1 -/- cells. Thus, it is likely that the synergistic effect is caused by inhibition of TDP1. Synergy was also found for
in other cancer cell lines. Thus, sensitizing cancer cells using a non-cytotoxic drug can enhance the efficacy of currently used pharmaceuticals and, concomitantly, reduce toxic side effects.
The paper describes a detector for carrying out diffraction experiments on a beam of synchrotron radiation, which is being developed at the Institute of Nuclear Physics of the Siberian Branch of the ...Russian Academy of Sciences. The detector will operate in the mode of direct counting of X-ray photons with an energy of more than 3–4 keV. A general description of the detector and its components is given, as well as a detailed description of the recording channel of an application-specific integrated circuit (ASIC). The results of the first measurements of the ASIC parameters are given and discussed in the article.
The electromagnetic CsI(Tl) calorimeter is one of the key systems in the Belle II detector. The calorimeter is aimed primarily at efficiently detecting photons over a wide energy range from several ...tens of MeV units to
GeV. A highly efficient data acquisition system is required for a continuous readout of signal events at a trigger rate corresponding to the maximum collider luminosity. Problems solved by such a system for the calorimeter of the Belle II detector are described.
Study of the Process in the Energy Range GeV Achasov, M. N.; Barnyakov, A. Yu; Beloborodov, K. I. ...
Physics of atomic nuclei,
2023/12, Letnik:
86, Številka:
6
Journal Article
Recenzirano
The
cross section is measured in the center-of-mass energy range from 1.07 to 2.00 GeV in the decay channel
,
. The data set with an integrated luminosity of 242 pb
accumulated in the experiment with ...the SND detector at the VEPP-2000
collider is analyzed.
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