The reaction of 2-arylcyclopropane-1,1-dicarboxylates (ACDCs) with the unsaturated cyclohepta-2,4,6-triene-1-carboxylate system under the action of GaCl
3
proceeds with a contraction of the ...seven-membered cycle and formally corresponds to the 2+4 or 3+2 cycloaddition of 1,2- or 1,3-zwitterionic intermediates generated from ACDCs to the double bonds of the norcaradiene structure. On the contrary, cycloheptatrienes with donor substituents practically do not form cycloaddition products in reactions with 1,2-zwitterionic intermediates, but undergo dehydrogenation and significant oligomerization. Methyl- and phenylcycloheptatriene turned out to be rather good precursors of hydride ions, which resulted in the formation of (2-phenylethyl)malonate, while 7-methoxycycloheptatriene predominantly transforms the 1,2-zwitterion open form to the initial ACDC.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Yakutsk Extensive Air Shower Array has been continuously operating for more than 50 years (since 1970) and up until recently it has been one of world’s largest ground-based instruments aimed at ...studying the properties of cosmic rays in the ultra-high energy domain. In this report we discuss results recently obtained at the array—on cosmic rays’ energy spectrum, mass composition and directional anisotropy—and how they fit into the world data. Special attention is paid to the measurements of muonic component of extensive air showers. Theoretical results of particle acceleration at shocks are also briefly reviewed. Future scientific and engineering plans on the array modernization are discussed.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The study investigated the reactivity of various CH-acids/conjugated bases in the synthesis of hepta(methoxycarbonyl)cycloheptatriene through a cascade reaction. NMR spectral monitoring identified ...(methoxycarbonyl)methylpyridinium as the true nucleophilic component in the original synthesis based on methyl diazoacetate. The scope of CH-acids capable of participating in the reaction was expanded to include sulfonium salts and sulfones, whereas certain nucleophiles were found to be ineffective. A correlation between the pKa values of CH-acids and the formation of seven-membered rings in the cascade reaction was established.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
optoelectronic properties of indium and tin oxide thin films depending on the oxygen content in the total gas flow were experimentally investigated during deposition of these films by DC magnetron ...target sputtering. Relationship of the hetero junction thin-film solar cell output parameters vs. oxygen partial pressure in a vacuum vessel was examined during indium and tin oxide layer deposition. The maximum photovoltaic conversion efficiency of the solar cell was achieved at an oxygen partial pressure in the vacuum vessel of ~6
.
5 Torr.
Full text
Available for:
FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study is to analyze the spectral characteristics of ascitic fluid using Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS). The utilization of SERS allows for detection ...the presence of ascitic fluid components that are not available for revealing when analyzed using conventional Raman spectroscopy. The potential to detect the spectral contribution of a number of pathogenic microorganisms utilizing the proposed SERS-based optical approach has been demonstrated.
Revision of the Task Force diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) has increased their sensitivity for the diagnosis of early and familial forms of ...the disease. The epsilon wave is a major diagnostic criterion in the context of ARVC/D, which, however, remains not quantifiable and therefore may leave room for substantial subjective interpretation.
The purpose of this study was to assess interobserver agreement in epsilon wave definition and epsilon wave importance for ARVC/D diagnosis.
Electrocardiographic (ECG) tracings depicting leads V1, V2, and V3 collected from individuals evaluated for ARVC/D (n = 30) were given to panel members who were asked to respond to the question whether ECG patterns meet epsilon wave definition outlined by the Task Force diagnostic criteria. The prevalence and importance of epsilon waves for ARVC/D diagnosis were assessed in a pooled data set of patients with definite ARVC/D from European and American registries (n = 815).
The number of ECG patterns identified as epsilon waves varied from 5 to 18 per reviewer (median 13 per reviewer). A unanimous agreement was reached for only 10 cases (33%), 2 of which qualified as epsilon waves and 8 as non-epsilon waves by all panel members. From a pooled data set, 106 patients reportedly had epsilon waves (13%). In 105 of 106 patients with epsilon waves (99%), exclusion of epsilon waves from the diagnostic score would not affect the "definite" diagnostic category.
Interobserver variability in the assessment of epsilon waves is high; however, the impact of epsilon waves on ARVC/D diagnosis is negligibly low. The results urge to exercise caution in the assessment of epsilon waves, especially in patients who would not otherwise meet diagnostic criteria.
Cycloheptatriene derivatives are studied by means of resonance electron capture negative ion mass spectrometry (REC NIMS). The average lifetimes of molecular negative ions (NIs) are measured with ...respect to electron autodetachment. Using the Arrhenius approach, electron affinity EA
a
of the molecules under study is estimated, and the effective temperature of the resulting negative molecular ions is determined as a function of the electron energy. It is assumed that the dissociation of negative molecular ions in the ground electronic state is a process similar to that of the thermal degradation of molecules.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aim
. To investigate on post-COVID period in patients of the Eurasian region.
Material and methods
. A total of 9364 consecutively hospitalized patients were included in ACTIV registry. Enrollment of ...patients began on June 29, 2020, and was completed on March 30, 2021, corresponding to the first and second waves of the pandemic. Demographic, clinical, and laboratory data, computed tomography (CT) results, information about inhospital clinical course and complications of COVID-19 during hospitalization were extracted from electronic health records using a standardized data collection form. The design included follow-up telephone interviews with a standard questionnaire at 3, 6, and 12 months to examine the course of post-COVID period.
Results
. According to ACTIV register, 63% of patients after COVID-19 had new adverse symptoms or exacerbations of the existing symptoms lasting for up to 1 year. After hospital discharge, 79,8% of patients sought unscheduled medical attention in the first 3 months, 79,1% at 4-6 months, and 64,8% at 7-12 months. Readmission rate was 11,8% in the first 3 months, 10,9% at 4-6 months, and 10,1% at 7-12 months. The most common reasons for unscheduled treatment in the first 3 months were uncontrolled hypertension, decompensated type 2 diabetes, destabilization of coronary artery disease, gastrointestinal disease, AF episodes, exacerbation of asthma and chronic obstructive pulmonary disease, decompensated heart failure (HF). The 12-month mortality of COVID-19 survivors after the discharge was 3,08%. Multivariate analysis showed that independent risk factors for fatal outcome were age (direct correlation), the levels of hemoglobin (inverse correlation), oxygen saturation (inverse correlation), and aspartate aminotransferase (direct correlation), as well as class III-IV HF, prior stroke, cancer, inhospital acute kidney injury. Based on these identified risk factors, a nomogram was constructed to determine the 3-month mortality risk after discharge.
Conclusion
. Analysis of ACTIV register showed that end of the acute phase of COVID-19 does not imply a complete recovery.
The microstructure and defect structure of low-carbon steel after equal-channel angular pressing and electroplastic rolling are considered. The influence of such treatment on the microhardness and ...impact strength of steel is established.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This collaborative statement from the International Society for Holter and Noninvasive Electrocardiology/Heart Rhythm Society/European Heart Rhythm Association/Asia-Pacific Heart Rhythm Society ...describes the current status of mobile health technologies in arrhythmia management. The range of digital medical tools and heart rhythm disorders that they may be applied to and clinical decisions that may be enabled are discussed. The facilitation of comorbidity and lifestyle management (increasingly recognized to play a role in heart rhythm disorders) and patient self-management are novel aspects of mobile health. The promises of predictive analytics but also operational challenges in embedding mobile health into routine clinical care are explored.
PDF
