727 research outputs found

    The youth in Kaliningrad, Gdansk and Klaipeda: geopolitical vision of the world, identity and images of the other

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    This work juxtaposes the analysis of the federal discourse on the exclave position of the Kaliningrad region in 1994-2012 based on the screening by the Nezavisimaya gazeta and the results of surveys of students at the Immanuel Kant Baltic Federal University and the Universities of Gdansk and Klaipeda using a similar questionnaire. Students of all three universities show latent dissatisfaction with employment prospects, which is manifested in the declared intention to emigrate. The orientation of young residents of Kaliningrad and their peers from Gdansk and Klaipeda towards prevailing connections with Europe is complicated by the uncertainty of the EU-Russia relations. Young residents of Gdansk and Klaipeda reproduce dated stereotypes, and their interest in the Kaliningrad region is limited. However, as the experience of the other countries suggests, local border traffic between the Kaliningrad region and the neighbouring Polish voivodeships can contribute to the improvement of mutual images. Long-lasting eforts to diversify cooperation and promote a positive image of Kaliningrad in the neighbouring Polish regions can prove worthwhile. Apart from the measures aimed at strengthening the region's economic base, it is necessary to increase the symbolic capital of Kaliningrad to achieve harmonious development of Kaliningrad identity

    Sudy of the Propagation of Decimeter Radiowaves in the Atmosphere of Venus with the Aid of AIS ''venera 4''

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    Radio wave propagation in Venus atmosphere based on approximating inhomogeneity of refractivit

    The stress-strain state of the flat rope of hoisting engine with considering their technical state

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    Obtained an analytical dependence for determining the tensile forces acting in cables of the fl at rubberized rope. It takes into account the design of the hoisting engine – the deviations of generating line of the drum from a straight and of the possible break of the cable in rope. A comprehensive account of the impact of various factors on the stress-strain state of the rope allows determining the loss of tractive capacity in operation on the hoisting engine. The results should be taken into account in the design and operation of hoisting and transporting machines with fl at traction bodies

    Domain structure and polarization reversal in ferroelectrics studied by atomic force microscopy

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    The ferroelectric domain structure and its dynamics under applied electric field have been studied with nanoscale resolution by atomic force microscopy (AFM). Two mechanisms responsible for the contrast between opposite domains are proposed: large built-in domains are delineated in friction mode due to the tip–sample electrostatic interaction, and small domains created by an external field are imaged in topography mode due to piezoelectric deformation of the crystal. The ability of effective control of ferroelectric domains by applying a voltage between the AFM tip and the bottom electrode is demonstrated. It is experimentally confirmed that the sidewise growth of domain proceeds through the nucleation process on the domain wall

    Domain structure and polarization reversal in ferroelectrics studied by atomic force microscopy

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    The ferroelectric domain structure and its dynamics under applied electric field have been studied with nanoscale resolution by atomic force microscopy (AFM). Two mechanisms responsible for the contrast between opposite domains are proposed: large built-in domains are delineated in friction mode due to the tip–sample electrostatic interaction, and small domains created by an external field are imaged in topography mode due to piezoelectric deformation of the crystal. The ability of effective control of ferroelectric domains by applying a voltage between the AFM tip and the bottom electrode is demonstrated. It is experimentally confirmed that the sidewise growth of domain proceeds through the nucleation process on the domain wall

    Π‘ΠΈΠ½Ρ‚Π΅Π· Ρ‚Π° N-алкілування Π΄Ρ–Π΅Ρ‚ΠΈΠ» 4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-5,6-дикарбоксилатів

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    It has been shown that the ternary condensation of oxaloacetic ester (diethyl 2-oxosuccinate), aromatic aldehydesΒ and 3-amino-1,2,4-triazole or 5-aminotetrazole in dimethylformamide results in formation of the corresponding diethyl 7-aryl-4,7-dihydroazolo[1,5-a]pyrimidin-5,6-dicarboxylates. By 1H NMR spectroscopy (according to the data of the chemical shifts of C(2)H-protons for the corresponding N(4)H- and N(4)-methylderivatives ofΒ 7-phenyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-5,6-dicarboxylate) it has been found that alkylation of 4,7-dihydro[1,2,4]azolo[1,5-a]pyrimidin-5,6-dicarboxylates in the acetonitrile–saturated water alkali system leads selectively to formation of N(4)-alkyl derivatives. Both the starting compounds obtained and their N(4)-methylsubstitutedΒ analogues together with relative diethyl 4-aryl-3,4-dihydropyrimidin-2(1H)-on-5,6-dicarboxylates, 6-unsubstitutedΒ 4-aryl-3,4-dihydropyrimidin-2(1H)-on-5-dicarboxylates and the derivatives of 6-COR-7-aryl-4,7-dihydro[1,2,4] triazolo[1,5-a]pyrimidines are the promising objects for studying benzyl C(7)-functionalization of 4,7-dihydroazoloΒ 1,5-a]pyrimidines, as well as of reactions associated with the presence of double C=C-bonds activated by twoΒ electron withdrawing groups. Obtaining of the key N(4)H- and N(4)Me-derivatives of 7-phenyl-4,7-dihydro[1,2,4]Β triazolo- and tetrazolo[1,5-a]pyrimidin-5,6-dicarboxylates also opens the way to the research of biological propertiesΒ of the compounds of this class. It is noteworthy that being a three-component one the reaction studied, without any doubts, are appropriate for the synthesis of the derivatives of 7-aryl-4,7-dihydro[1,2,4]triazolo- andΒ tetrazolo[1,5-a]pyrimidines containing two electron withdrawing substituents in positions 5 and 6.Показано, Ρ‡Ρ‚ΠΎ трСхкомпонСнтная кондСнсация щавСлСвоуксусного эфира (диэтил 2-оксосукцината), ароматичСских альдСгидов ΠΈ 3-Π°ΠΌΠΈΠ½ΠΎ-1,2,4-Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»Π° ΠΈΠ»ΠΈ 5-Π°ΠΌΠΈΠ½ΠΎΡ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»Π° Π² Π΄ΠΈΠΌΠ΅Ρ‚ΠΈΠ»Ρ„ΠΎΡ€ΠΌΠ°ΠΌΠΈΠ΄Π΅ ΠΏΡ€ΠΈΠ²ΠΎΠ΄ΠΈΡ‚ ΠΊ ΠΎΠ±Ρ€Π°Π·ΠΎΠ²Π°Π½ΠΈΡŽ ΡΠΎΠΎΡ‚Π²Π΅Ρ‚ΡΡ‚Π²ΡƒΡŽΡ‰ΠΈΡ… диэтил 7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-5,6-дикарбоксилатов. Π‘ ΠΏΠΎΠΌΠΎΡ‰ΡŒΡŽ 1Н ЯМР-спСктроскопии (ΠΏΠΎ Π΄Π°Π½Π½Ρ‹ΠΌ химичСских сдвигов сигналов ΠΏΡ€ΠΎΡ‚ΠΎΠ½ΠΎΠ² Π‘(2)H для ΡΠΎΠΎΡ‚Π²Π΅Ρ‚ΡΡ‚Π²ΡƒΡŽΡ‰ΠΈΡ… N(4)H- ΠΈ N(4)МС-ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄Π½Ρ‹Ρ… диэтил 7-Ρ„Π΅Π½ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ[1,5-a]Β ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-5,6-дикарбоксилата) установлСно, Ρ‡Ρ‚ΠΎ Π°Π»ΠΊΠΈΠ»ΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠ΅ 7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-5,6-дикарбоксилатов Π² систСмС Π°Ρ†Π΅Ρ‚ΠΎΠ½ΠΈΡ‚Ρ€ΠΈΠ»-насыщСнная водная Ρ‰Π΅Π»ΠΎΡ‡ΡŒ сСлСктивно ΠΏΡ€ΠΈΠ²ΠΎΠ΄ΠΈΡ‚ ΠΊ ΠΎΠ±Ρ€Π°Π·ΠΎΠ²Π°Π½ΠΈΡŽ N(4)-Π°Π»ΠΊΠΈΠ»ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄Π½Ρ‹Ρ…. Как ΠΏΠΎΠ»ΡƒΡ‡Π΅Π½Π½Ρ‹Π΅ исходныС соСдинСния, Ρ‚Π°ΠΊ ΠΈ ΠΈΡ… N(4)-ΠΌΠ΅Ρ‚ΠΈΠ»Π·Π°ΠΌΠ΅Ρ‰Π΅Π½Π½Ρ‹Π΅ Π°Π½Π°Π»ΠΎΠ³ΠΈ наряду с родствСнными диэтил 4-Π°Ρ€ΠΈΠ»-3,4-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-2(1Н)-ΠΎΠ½-5,6-дикарбоксилатами, 6-Π½Π΅Π·Π°ΠΌΠ΅Ρ‰Π΅Π½Π½Ρ‹ΠΌΠΈ этил 4-Π°Ρ€ΠΈΠ»-3,4-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-2(1Н)-ΠΎΠ½-5-карбоксилатами ΠΈΒ ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄Π½Ρ‹ΠΌΠΈ 6-COR-7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½ΠΎΠ² ΡΠ²Π»ΡΡŽΡ‚ΡΡ пСрспСктивными ΠΎΠ±ΡŠΠ΅ΠΊΡ‚Π°ΠΌΠΈ для изучСния бСнзильной Π‘(7)-Ρ„ΡƒΠ½ΠΊΡ†ΠΈΠΎΠ½Π°Π»ΠΈΠ·Π°Ρ†ΠΈΠΈ 4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½ΠΎΠ², Π° Ρ‚Π°ΠΊΠΆΠ΅ Ρ€Π΅Π°ΠΊΡ†ΠΈΠΉ, связанных с Π½Π°Π»ΠΈΡ‡ΠΈΠ΅ΠΌ Π΄Π²ΠΎΠΉΠ½ΠΎΠΉ C=C-связи, Π°ΠΊΡ‚ΠΈΠ²ΠΈΡ€ΠΎΠ²Π°Π½Π½ΠΎΠΉ двумя Π°ΠΊΡ†Π΅ΠΏΡ‚ΠΎΡ€Π½Ρ‹ΠΌΠΈ Π³Ρ€ΡƒΠΏΠΏΠ°ΠΌΠΈ. ΠŸΠΎΠ»ΡƒΡ‡Π΅Π½ΠΈΠ΅ ΠΊΠ»ΡŽΡ‡Π΅Π²Ρ‹Ρ… N(4)H- ΠΈ N(4)МС-ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄Π½Ρ‹Ρ… 7-Ρ„Π΅Π½ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ- ΠΈ Ρ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½-5,6-дикарбоксилатов Ρ‚Π°ΠΊΠΆΠ΅ ΠΎΡ‚ΠΊΡ€Ρ‹Π²Π°Π΅Ρ‚ ΠΏΡƒΡ‚ΡŒ ΠΊ биологичСским исслСдованиям соСдинСний этого класса. Π—Π°ΠΌΠ΅Ρ‚ΠΈΠΌ, Ρ‡Ρ‚ΠΎ исслСдованная рСакция, являясь Ρ‚Ρ€Π΅Ρ…ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ‚Π½ΠΎΠΉ, бСзусловно ΠΏΠΎΠ΄Ρ…ΠΎΠ΄ΠΈΡ‚ для синтСза ΠΈ исслСдования ΠΊΠΎΠΌΠ±ΠΈΠ½Π°Ρ‚ΠΎΡ€Π½Ρ‹Ρ… Π±ΠΈΠ±Π»ΠΈΠΎΡ‚Π΅ΠΊ ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄Π½Ρ‹Ρ… 7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³ΠΈΠ΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ- ΠΈ Ρ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΠΈΡ€ΠΈΠΌΠΈΠ΄ΠΈΠ½ΠΎΠ², содСрТащих Π΄Π²Π° элСктроноакцСпторных замСститСля Π² полоТСниях 5 ΠΈ 6.Показано, Ρ‰ΠΎ Ρ‚Ρ€ΠΈΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ‚Π½Π° кондСнсація Ρ‰Π°Π²Π»Π΅Π²ΠΎΠΎΡ†Ρ‚ΠΎΠ²ΠΎΠ³ΠΎ СстСру (Π΄Ρ–Π΅Ρ‚ΠΈΠ» 2-оксосукцинату), Π°Ρ€ΠΎΠΌΠ°Ρ‚ΠΈΡ‡Π½ΠΈΡ… Π°Π»ΡŒΠ΄Π΅Π³Ρ–Π΄Ρ–Π² Ρ‚Π° 3-Π°ΠΌΡ–Π½ΠΎ-1,2,4-Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»Ρƒ Π°Π±ΠΎ 5-Π°ΠΌΡ–Π½ΠΎΡ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»Ρƒ Π² Π΄ΠΈΠΌΠ΅Ρ‚ΠΈΠ»Ρ„ΠΎΡ€ΠΌΠ°ΠΌΡ–Π΄Ρ– ΠΏΡ€ΠΈΠ·Π²ΠΎΠ΄ΠΈΡ‚ΡŒΒ Π΄ΠΎ утворСння Π²Ρ–Π΄ΠΏΠΎΠ²Ρ–Π΄Π½ΠΈΡ… Π΄Ρ–Π΅Ρ‚ΠΈΠ» 4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-5,6-дикарбоксилатів. Π—Π° допомогою 1Н ЯМР-спСктроскопії (Π·Π° Π΄Π°Π½ΠΈΠΌΠΈ ΠΏΡ€ΠΎ Ρ…Ρ–ΠΌΡ–Ρ‡Π½Ρ– зсуви сигналів ΠΏΡ€ΠΎΡ‚ΠΎΠ½Ρ–Π² Π‘(2)Н для Π²Ρ–Π΄ΠΏΠΎΠ²Ρ–Π΄Π½ΠΈΡ… N(4)H- Ρ‚Π°Β N(4)Me-ΠΏΠΎΡ…Ρ–Π΄Π½ΠΈΡ… Π΄Ρ–Π΅Ρ‚ΠΈΠ» 7-Ρ„Π΅Π½Ρ–Π»-4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-5,6-дикарбоксилатів) вста-Π½ΠΎΠ²Π»Π΅Π½ΠΎ, Ρ‰ΠΎ алкілування 4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-5,6-дикарбоксилатів Ρƒ систСмі ацСтонітрилнасичСний Π²ΠΎΠ΄Π½ΠΈΠΉ Π»ΡƒΠ³ сСлСктивно ΠΏΡ€ΠΈΠ·Π²ΠΎΠ΄ΠΈΡ‚ΡŒ Π΄ΠΎ утворСння N(4)-Π°Π»ΠΊΡ–Π»ΠΏΠΎΡ…Ρ–Π΄Π½ΠΈΡ…. Π―ΠΊ ΠΎΡ‚Ρ€ΠΈΠΌΠ°Π½Ρ– вихідні сполуки, Ρ‚Π°ΠΊ Ρ– Ρ—Ρ…Π½Ρ– N(4)-ΠΌΠ΅Ρ‚ΠΈΠ»Π·Π°ΠΌΡ–Ρ‰Π΅Π½Ρ– Π°Π½Π°Π»ΠΎΠ³ΠΈ поряд Π·Ρ– споріднСними Π΄Ρ–Π΅Ρ‚ΠΈΠ» 4-Π°Ρ€ΠΈΠ»-3,4-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-2(1Н)-ΠΎΠ½-5,6-дикарбоксилатами, 6-Π½Π΅Π·Π°ΠΌΡ–Ρ‰Π΅Π½ΠΈΠΌΠΈ Π΅Ρ‚ΠΈΠ» 4-Π°Ρ€ΠΈΠ»-3,4-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-2(1Н)-ΠΎΠ½-5-карбоксилатами Ρ‚Π° ΠΏΠΎΡ…Ρ–Π΄Π½ΠΈΠΌΠΈ 6-COR-7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½Ρ–Π² Ρ” пСрспСктивними об’єктами для вивчСння Π±Π΅Π½Π·ΠΈΠ»ΡŒΠ½ΠΎΡ— Π‘(7)-Ρ„ΡƒΠ½ΠΊΡ†Ρ–ΠΎΠ½Π°Π»Ρ–Π·Π°Ρ†Ρ–Ρ— 4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎΠ°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½Ρ–Π², Π° Ρ‚Π°ΠΊΠΎΠΆ Ρ€Π΅Π°ΠΊΡ†Ρ–ΠΉ, пов’язаних Π· Π½Π°ΡΠ²Π½Ρ–ΡΡ‚ΡŽ ΠΏΠΎΠ΄Π²Ρ–ΠΉΠ½ΠΎΠ³ΠΎ C=C-зв’язку, Π°ΠΊΡ‚ΠΈΠ²ΠΎΠ²Π°Π½ΠΎΠ³ΠΎ Π΄Π²ΠΎΠΌΠ° Π°ΠΊΡ†Π΅ΠΏΡ‚ΠΎΡ€Π½ΠΈΠΌΠΈ Π³Ρ€ΡƒΠΏΠ°ΠΌΠΈ. ΠžΡ‚Ρ€ΠΈΠΌΠ°Π½Π½ΡΒ ΠΊΠ»ΡŽΡ‡ΠΎΠ²ΠΈΡ… N(4)H- Ρ– N(4)МС-ΠΏΠΎΡ…Ρ–Π΄Π½ΠΈΡ… 7-Ρ„Π΅Π½Ρ–Π»-4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ- Ρ‚Π° Ρ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½-5,6-дикарбоксилатів Ρ‚Π°ΠΊΠΎΠΆ Π²Ρ–Π΄ΠΊΡ€ΠΈΠ²Π°Ρ” ΡˆΠ»ΡΡ… Π΄ΠΎ Π±Ρ–ΠΎΠ»ΠΎΠ³Ρ–Ρ‡Π½ΠΈΡ… Π΄ΠΎΡΠ»Ρ–Π΄ΠΆΠ΅Π½ΡŒ сполук Ρ†ΡŒΠΎΠ³ΠΎ класу. Π’Ρ–Π΄Π·Π½Π°Ρ‡ΠΈΠΌΠΎ,Β Ρ‰ΠΎ дослідТСна рСакція, Π±ΡƒΠ΄ΡƒΡ‡ΠΈ Ρ‚Ρ€ΠΈΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ‚Π½ΠΎΡŽ, Π±Π΅Π·ΡƒΠΌΠΎΠ²Π½ΠΎ ΠΏΡ–Π΄Ρ…ΠΎΠ΄ΠΈΡ‚ΡŒ для синтСзу Ρ‚Π° дослідТСння комбінаторних Π±Ρ–Π±Π»Ρ–ΠΎΡ‚Π΅ΠΊ ΠΏΠΎΡ…Ρ–Π΄Π½ΠΈΡ… 7-Π°Ρ€ΠΈΠ»-4,7-Π΄ΠΈΠ³Ρ–Π΄Ρ€ΠΎ[1,2,4]Ρ‚Ρ€ΠΈΠ°Π·ΠΎΠ»ΠΎ- Ρ‚Π° Ρ‚Π΅Ρ‚Ρ€Π°Π·ΠΎΠ»ΠΎ[1,5-a]ΠΏΡ–Ρ€ΠΈΠΌΡ–Π΄ΠΈΠ½Ρ–Π²,Β Ρ‰ΠΎ ΠΌΡ–ΡΡ‚ΡΡ‚ΡŒ Π΄Π²Π° Π΅Π»Π΅ΠΊΡ‚Ρ€ΠΎΠ½ΠΎΠ°ΠΊΡ†Π΅ΠΏΡ‚ΠΎΡ€Π½Ρ– замісники Ρƒ полоТСннях 5 Ρ‚Π° 6

    Crossover from hydrodynamic to acoustic drag on quartz tuning forks in normal and superfluid 4He

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    We present measurements of the drag forces on quartz tuning forks oscillating at low velocities in normal and superfluid 4He. We have investigated the dissipative drag over a wide range of frequencies, from 6.5 to 600 kHz, by using arrays of forks with varying prong lengths and by exciting the forks in their fundamental and first overtone modes. At low frequencies the behavior is dominated by laminar hydrodynamic drag, governed by the fluid viscosity. At higher frequencies acoustic drag is dominant and is described well by a three-dimensional model of sound emission

    Nanoscale resolution immersion scanning thermal microscopy

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    Nanoscale thermal properties are becoming of extreme importance for modern electronic circuits that dissipate increasing power on the length scale of few tens of nanometers, and for chemical and physical properties sensors and biosensors using nanoscale sized features. While Scanning Thermal Microscopy (SThM) is known for its ability to probe thermal properties and heat generation with nanoscale resolution, until today it was perceived impossible to use it in the liquid environment due to dominating direct heat exchange between microfabricated thermal probe and surrounding liquid that would deteriorate spatial resolution. Nonetheless, our theoretical analysis of SThM in liquids showed that for certain design of SThM probe with resistive heater located near the probe tip, their thermal signal is only moderately affected, by less than half on immersion in a dodecane environment. More significantly, its spatial resolution, surprisingly, would remain practically unaffected, and the thermal contact between the tip apex and the studied sample would be beneficially improved. Our experimental trials of such immersion SThM, or iSThM, were fully successful and here we report for the first time nanoscale SThM measurements of thermal conductivity of Ultra Large Scale Integration polymerceramic metal interconnects with the spatial thermal resolution down to 50 nm. Further studies of heat transport in nanoscale graphite flakes in iSThM suggested, in particular, that highly anisotropic thermal conductivity in graphene layers may play significant role in the nanoscale thermal transport in liquid environment. New iSThM opens a wide range of applications from noncontact measurements of thermal transport in semiconductor devices to exploring graphene energy storage, catalytic reactions and heat generation in biological systems

    Measurements of vortex line density generated by a quartz tuning fork in superfluid 4^{4} 4 He

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    We present proof-of-concept measurements of the vortex line density generated by a quartz tuning fork resonator probed by the attenuation of second sound in superfluid 4He at 1.6 K. The force–velocity response of a quartz tuning fork operating at a frequency of 31 kHz exhibited the onset of extra damping at a velocity of 0.5 msβˆ’1. Attenuation of the 5th resonant mode of second sound was observed at the same velocity, indicating the production of vortex lines. Our measurements demonstrate that an increase of the drag coefficient corresponds to the development of quantum turbulence
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