Log-optimal (d+2)-configurations in d-dimensions

We enumerate and classify all stationary logarithmic configurations of d+2 points on the unit (d-1)-sphere in d-dimensions. In particular, we show that the logarithmic energy attains its relative minima at configurations that consist of two orthogonal to each other regular simplexes of cardinality m and n. The global minimum occurs when m=n if d is even and m=n+1 otherwise. This characterizes a new class of configurations that minimize the logarithmic energy on the (d-1)-sphere for all d. The other two classes known in the literature, the regular simplex and the cross polytope, are both universally optimal configurations.Comment: 17 page

Complex formation of 1-hydroxyethylidene-1,1-diphosphonic acid with gadolinium(III) and calcium(II) in the aqueous solutions

The complex formation constant have been determined for the reactions of 1-hydroxyethylidenediphosphonic acid (H4L) with Ca(II) and Gd(III). The solubility constant has been estimated for the products differing in the ligand deprotonation state. In the cases of both cations, four complex types are common: Me(H2L)2, MeH3L2, Me 2L, and Me2(HL)2. The Gd(H2L) 2 and GdH3L2 complexes are much more stable than the respective calcium complexes. It has been demonstrated that, on the contrary to the commonly accepted practice, gadolinium ion cannot model the behavior of calcium ions. © 2013 Pleiades Publishing, Ltd

Geometrical Frustration: A Study of 4d Hard Spheres

The smallest maximum kissing-number Voronoi polyhedron of 3d spheres is the icosahedron and the tetrahedron is the smallest volume that can show up in Delaunay tessalation. No periodic lattice is consistent with either and hence these dense packings are geometrically frustrated. Because icosahedra can be assembled from almost perfect tetrahedra, the terms "icosahedral" and "polytetrahedral" packing are often used interchangeably, which leaves the true origin of geometric frustration unclear. Here we report a computational study of freezing of 4d hard spheres, where the densest Voronoi cluster is compatible with the symmetry of the densest crystal, while polytetrahedral order is not. We observe that, under otherwise comparable conditions, crystal nucleation in 4d is less facile than in 3d. This suggest that it is the geometrical frustration of polytetrahedral structures that inhibits crystallization.Comment: 4 pages, 3 figures; revised interpretatio

New Details to Relaxation Dynamics of Dielectric Composite Materials Comprising Longitudinally Opened Carbon Nanotubes

© 2017 American Chemical Society. The difference between intact and longitudinally opened multiwalled carbon nanotubes (referred to as CNT and OCNT) has been studied in their application as conductive filler in polymer composite materials. The dielectric properties have been studied in a broad frequency range at the temperatures varying from 293 K through 373 K. Introduction of as little as 0.5% and 1.0% of the conductive filler dramatically increased both parts of the complex permittivity. The percolation threshold is registered at ∼1.5% filling fraction. The main frequency dispersion of the dielectric permittivity lies in the low frequency end of the tested spectrum: from 10 2 Hz through 10 4 Hz. At equal filling fractions, the permittivity of the OCNT-based samples exceeds that of the intact CNT-based samples. The relaxation dynamics is largely affected by the nanoscale geometry of the filler: the temperature dependence of such parameters as dielectric strength, activation energy, and relaxation time demonstrated significant difference between the charge transfer mechanism in the CNT-based and OCNT-based samples. The obtained activation energy is 150 and 85 kJ/mol for materials comprising CNTs and OCNTs, respectively. The relaxation mechanism is complex, and the exact factors behind the macroscopic dielectric properties of the tested materials cannot be singled out with certainty. Several experimental data points suggest that the individual nanotubes, not their aggregates, play the major role in the observed electrical properties of the composites. At the low loading fractions, we attained the highest dielectric strength values among all the data reported by the present day for the CNT/polymer host systems

Homogeneous Liquid Phase Transfer of Graphene Oxide into Epoxy Resins

© 2017 American Chemical Society.The quality of polymer composite materials depends on the distribution of the filler in the polymer matrix. Due to the presence of the oxygen functional groups, graphene oxide (GO) has a strong affinity to epoxy resins, providing potential opportunity for the uniform distribution of GO sheets in the matrix. Another advantage of GO over its nonoxidized counterpart is its ability to exfoliate to single-atomic-layer sheets in water and in some organic solvents. However, these advantages of GO have not yet been fully realized due to the lack of the methods efficiently introducing GO into the epoxy resin. Here we develop a novel homogeneous liquid phase transfer method that affords uniform distribution, and fully exfoliated condition of GO in the polymer matrix. The most pronounced alteration of properties of the cured composites is registered at the 0.10%-0.15% GO content. Addition of as little as 0.10% GO leads to the increase of the Young's modulus by 48%. Moreover, we demonstrate successful introduction of GO into the epoxy matrix containing an active diluent-modifier; this opens new venues for fabrication of improved GO-epoxy-modifier composites with a broad range of predesigned properties. The experiments done on reproducing the two literature methods, using alternative GO introduction techniques, lead to either decrease or insignificant increase of the Young's modulus of the resulting GO-epoxy composites

Reactions of arylenedioxytrihalophosphoranes with acetylenes 14. Methoxyphenylacetylenes in the reaction with 2,2,2-trichlorobenzo-1,3,2-dioxaphosphole

© 2016, Springer Science+Business Media New York.Reactions of 2,2,2-trichlorobenzo-1,3,2-dioxaphosphole with 2-, 3-, 4-methoxyphenyl-, 3,4-dimethoxyphenyl- and 2,3,4-trimethoxyphenylacetylenes furnished 4-phenylbenzo-1,2-oxaphosphinine derivatives. The presence of one, two, or three donor methoxy groups in the aromatic ring of phenylacetylene does not change the general direction of the reaction which is characteristic of arylacetylenes and lead to 4-arylareno-1,2-oxaphosphinine derivatives. The presence of substituents in the exocyclic aryl group at ortho-position to the oxaphosphinine ring led to the appearance of atropoisomers

ПРЯМОЕ ОПРЕДЕЛЕНИЕ ЗОЛОТА В СУСПЕНЗИЯХ СТАНДАРТНЫХ ОБРАЗЦОВ ГОРНЫХ ПОРОД И РУДЫ МЕТОДОМ ЭЛЕКТРОТЕРМИЧЕСКОЙ АТОМНО-АБСОРБЦИОННОЙ СПЕКТРОМЕТРИИ ВЫСОКОГО РАЗРЕШЕНИЯ Ю.А. Захаров, Д.С. Ирисов, Р.В. Окунев, Р.Х. Мусин, Р.Р. Хайбуллин

High resolution continuum source atomic absorption spectrometer ContrAA-700 with graphite furnace is used for direct gold determination in rocks and ores on the level 10-6-10-3 % mas. Russian standard reference materials of gold containing ore СЗР-4 (2.13 ± 0.05 g/ton), black slates of Sykhoy Log СЛг-1 (2.50 ± 0.03 g/ton) and СЧС-1 (0.10 ± 0.02 g/ton) in mass 1 mg was inserted into the furnace in the suspension form prepared on the mix of concentrated HNO3 and HCl (1:3) with following sevenfold dilution by water. It was revealed that spectral lines of gold have dense fine structured spectral interferences of different molecules of the matrix. Absorption resonance line Au 242.8 nm is overlapped by left wing of very intensive SiO band. Twice as less sensitive line Au 267.6 nm is in a narrow gap between the molecular components. Strong matrix depression of the analytical signal and intensive background at usual one-stage atomization do the analysis impossible if gold concentration less 2 g/ton. Application of the additional accessory Atzond-1 for two-stage probe atomization provides ability for automatic dozing of the suspensions and reduces the matrix interference. Due to fractionation of the sample vapors on the tungsten probe the line Au 267.6 nm, in difference from resonance line Au 242.8 nm, is completely freed from the spectral overlapping and provides lower quantitative limit of gold determination 0.05 g/ton (Sr =30 %; n = 5; Р= 0.95).Keywords: atomic absorption spectrometry, graphite atomizer, double-stage probe atomization, gold, silver, rocks, ores, black slate, suspension (Russian)DOI: http://dx.doi.org/10.15826/analitika.2014.18.4.004  Y.А. Zakharov, D.S. Irisov1, R.V. Okunev, R.Kh. Musin, R.R. HaibullinKazan (Volga region) Federal University, Kazan, Russian Federation1LLC «Atzond», Kazan, Russian FederationREFERENCES 1. Busev A.I., Ivanov V.M. Analiticheskaia khimiia zolota [Analytical chemistry of gold]. Moscow, Nauka, 1973. 263 p. (in Russian). 2. Vasilyeva I.E., Pozhidaev Yu.N., Vlasova N.N., Voronkov M.G., Philipchenko Yu.A. [Sorption-atomic-emission determination of gold, platinum and palladium in rocks and ores using sorbent PSTM-3Т]. Analitika i kontrol' [Analytics and control], 2010, vol. 14, no. 1, pp. 16-24. (in Russian). 3. Judelevich I.G., Starceva E.A. Atomno-absorbtsionnoe opredelenie blagorodnykh metallov [Atomic absorption determination of noble metals]. Novosibirsk, Nauka, 1981. 159 p. (in Russian). 4. Balaram V., Mathur R., Satyanarayanan M., Sawant S. S., Roy P., Subramanyam K. S. V., Kamala C. T., Anjaiah K. V., Ramesh S. L., Dasaram B. A Rapid Method for the Determination of Gold in Rocks, Ores and Other Geological Materials by F-AAS and GF-AAS After Separation and Preconcentration by DIBK Extraction for Prospecting Studies. MAPAN-Journal of Metrology Society of India, 2012, vol. 27, no. 2, pp. 87-95. doi: 10.1007/s12647-012-0012-2 5. Reddi G. S., Rao C. R. M. Analytical techniques for the determination of precious metals in geological and related materials. Analyst, 1999, vol. 124, pp. 1531-1540. 6. Shvetsov V. A. Probirnyi analiz pri razvedke zolotorudnykh mestorozhdenii. Diss. dokt. him. nauk. [The assay analysis at investigation of gold fields. Dr. chem. sci. diss.]. Irkutsk, 2006. 259 p. (in Russian). 7. Vasilyeva I.E., Shabanova E.V., Busko A.E., Kunaev A.B. [Estimation of Au- and Ag- particle sizes in geological samples using high time-resolved scintillation atomic emission analysis]. Analitika i kontrol' [Analytics and control], 2010, vol. 14, no. 4, pp. 201-213. (in Russian). 8. Konyshev V.O. [Experience of sampling error evaluation and development of methodology to explore a deposit with bonanza gold distribution]. Otechestvennaia geologiia [Domestic geology], 2004, no. 6, pp. 22-34. 9. Resano M., Aramendı´a M., Garcia-Ruiz E. and Belarra M. A. Solid sampling-graphite furnace atomic absorption spectrometry for the direct determination of Au in samples of various natures. J. Anal. At. Spectrom., 2005, vol. 20, pp. 479-481. 10. Zakharov Y.А., Okunev R.V., Hasanova S.I., Irisov D.S., Haibullin R.R. [Atomic absorption determination of gold and silver in rocks and ores using double-stage probe atomization in the graphite furnace]. Analitika i kontrol' [Analytics and control], 2013, vol. 17, no. 4, pp. 414-422 (in Russian). 11. Welz B., Becker-Ross H., Florek S., Heitmann U. High-Resolution Continuum Source AAS: The Better Way to Do Atomic Absorption Spectrometry. Weinheim, WILLEY-VCH, Verlag GmbHCo. KGaA, 2005. 295 p. 12. Gunduz S., Akman S. Determination of lead in rice grains by solid sampling HR-CS GFAAS. Food Chemistry, 2013, vol. 141, pp. 2634-2638. 13. Boschetti W., Borges A.R., DuarteA.T., Dessuy M.B., Vale M.G.R., de Andrade J.B. and Welz B. Simultaneous determination of Mo and Ni in wine and soil amendments by HR-CS GF AAS. Anal. Methods, 2014, vol. 6, pp. 4247-4256. 14. Castilho I.N., Pereira E.R., Welz B., Shaltout A.A., Caraseka E. and Martens I.B.G. Determination of selenium in soil samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis. Anal. Methods, 2014, vol. 6, pp. 2870-2875. 15. Castilho I.N., Welz B., Vale M.G., de Andrade J.B., Smichowski P., Shaltout A.A., Colares L., Carasek E. Comparison of three different sample preparation procedures for the determination of traffic-related elements in airborne particulate matter collected on glass fiber filters. Talanta, 2012, vol. 88, pp. 689–695. 16. Resano M., Mozas E., Crespo C., Briceсo J., del Campo Menoyoa J. and Belarra M. A. Solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry to monitor the biodistribution of gold nanoparticles in mice tissue after intravenous administration. J. Anal. At. Spectrom., 2010, vol. 25. pp. 1864-1873. 17. Zakharov Y.A., Haibullin R.R., Irisov D. S., Sadykov M. F., Gainutdinov A. R. [Hardware-software complex for atomic absorption spectrometry with multistage probe atomization]. Naychnoe priborostroenie [Scientific instrumentation], 2013, vol. 23, no 4, pp. 104-111. 18. Federal state budgetary institution of science A.P. Vinogradov Institute of Geochemistry SB RAS. Available at: http://www.igc.irk.ru/Innovation/Standarts-obr/Catalog-2013.pdf (accessed 01 July 2014). 19. Pupyshev A.A. Atomno-absorbtsionnyi spectral`nyi analiz [Atomic absorption spectral analysis]. Moscow, Technosphera Publ., 2009. 782 с. (in Russian). 20. López-Garcia I., Campillo N., Arnau-Jerez I., Hernández-Córdoba M. Slurry sampling for the determination of silver and gold in soils and sediments using electrothermal atomic absorption spectrometry. Spectrochim. Acta, 2003, vol. 58B, pp. 1715-1721. 21. Kurilko S. S., Put'makov A. N., Labusov V. A., Borovikov V. M., Seliunin D. O. Materialy XIII Mezhdunarodnogo simpoziuma «Primenenie analizatorov MAJeS v promyshlennosti» [Proc. 13th Int. Symp. "The use of MAES analyzers in the industry"]. Novosibirsk, 2013, pp. 40-50 (in Russian). 22. Katskov D.A., Khanye G.E. Simultaneous Multi-Element Electrothermal Atomic Absorption Determination Using a Low Resolution CCD Spectrometer and Continuum Light Source: The Concept and Methodology. S. Afr. J. Chem., 2010, vol. 63, pp. 45-57. 23. Gibson J., Katskov D.A. Simultaneous Determination of Metals in Coal with Low-Resolution Continuum Source Atomic Absorption Spectrometer and Filter Furnace Atomizer. S. Afr. J. Chem,. 2011, vol. 64, pp. 79-87. 24. Katskov D.A., Sadagov Yu.M. Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry. Spectrochim. Acta, 2011, vol. 66B, pp. 451-460. 25. Kurfürst U. Solid Sample Analysis: Direct and Slurry Sampling Using GF-AAS and ETV-ICP. Berlin: Springer, 1998. 423 р. 26. Slurry sampling for direct analysis of solid materials by electrothermal atomic absorption spectrometry (ETAAS). A literature review from 1990 to 2000 / M.J. Cal-Prieto et [al.] // Talanta. 2002. V. 56. P. 1-51. 27. Zakharov Y.A., Kokorina O.B., Gil'mutdinov A.K. [Concentrating of determined elements on the probe in electrothermal atomizer]. Zhurnal prikladnoi spektroskopii [Journal of Applied Spectroscopy], 2005, vol. 72, no. 2, pp. 256-259 (in Russian).Атомно-абсорбционный спектрометр высокого разрешения ContrAA-700 с графитовой печью применен для прямого определения золота в горных породах и рудах на уровне 10-6-10-3 % мас.В печь вводили навески 1 мг стандартных образцов золотосодержащей руды СЗР-4 (2.13 ± 0.05 г/т), черных сланцев Сухого Лога СЛг-1 (2.5 ± 0.3 г/т) и СЧС-1 (0.10 ± 0.02 г/т) в виде суспензий, приготовленных на смеси концентрированных HNO3 и HCl (1 : 3) с последующим семикратным разбавлением водой. Выявлено наличие плотного окружения спектральных линий золота тонко структурированнымиполосами поглощения разнообразных молекул матрицы. Резонансная линия поглощения Au 242.8 нм перекрыта левым крылом очень интенсивной полосы  SiO.  В два раза менее чувствительная линия Au 267.6 нм находится в узком промежутке между спектральными молекулярными компонентами.  Из-за сильного подавления аналитического сигнала и интенсивного неселективного поглощения определение с использованием одностадийной атомизации крайне затруднено и может осуществляться при концентрации золота не менее 2 г/т. Использование приставки АТЗОНД-1 для осуществления двухстадийной зондовой атомизации позволило автоматически дозировать суспензии и снизить матричные помехи. За счет фракционирования паров пробы на вольфрамовом зонде линия Au 267.6 нм, в отличие от резонансной линии  Au  242.8 нм, освобождается от спектральных наложений и обеспечивает более низкий предел количественного определения золота 0.05 г/т (Sr =30 %; n = 5; Р = 0.95).Ключевые слова: атомно-абсорбционная спектрометрия, графитовый атомизатор, суспензия, золото, горная порода, черный сланец, двухстадийная зондовая атомизация DOI: http://dx.doi.org/10.15826/analitika.2014.18.4.004  ЛИТЕРАТУРА1. Бусев А.И., Иванов В.М. Аналитическая химия золота. М.: Наука, 1973. 263 с.2. Сорбционно-атомно-эмиссионное определение золота, платины и палладия в горных породах и рудах с использованием сорбента ПСТМ-З / И.Е. Васильева [и др.] // Аналитика и контроль. 2010. Т. 14, № 1. С. 16-24.3. Юделевич И.Г., Старцева Е.А. Атомно-абсорбционное определение благородных металлов. Новосибирск: Наука, 1981. 159 с.4. ARapid Method for the Determination of Gold in Rocks, Ores and Other Geological Materials by F-AAS and GF-AAS After Separation and Preconcentration by DIBK Extraction for Prospecting Studies / V. Balaram [et al.] // MAPAN-Journal of Metrology Society of India. 2012. V. 27, № 2. P. 87-95.5. Reddi G.S., Rao C.R.M. Analytical techniques for the determination of precious metals in geological and related materials // Analyst. 1999. V. 124. P. 1531-1540.6. Швецов В.А. Пробирный анализ при разведке золоторудных месторождений: дис. …  д-ра хим. наук. Иркутск, 2006. 259 с.7. Методика определения содержания золота и серебра в геологических образцах с использованием сцинтилляционного атомно-эмиссионного анализа с высоким временным разрешением/ И.Е. Васильева [и др.] // Аналитика и контроль. 2010. Т. 14, № 4. С. 201-213.8. Конышев В.О. Опыт оценки погрешностей опробования и совершенствование методологии разведки месторождения с бонанцевым распределением золота // Отечественная геология, 2004. № 6. С. 22-34.9. Solid sampling-graphite furnace atomic absorption spectrometry for the direct determination of Au in samples of various natures / M. Resano [et al.] // J. Anal. At. Spectrom. 2005. V. 20. 479-481.10. Атомно-абсорбционное определение золота и серебра в породах и рудах с помощью двухстадийной зондовой атомизации в графитовой печи / Ю.А. Захаров [и др.] // Аналитика и контроль. 2013. Т. 17, № 4. С. 414-422.11. Welz B., Becker-Ross H., Florek S., Heitmann U. High-Resolution Continuum Source AAS: The Better Way to Do Atomic Absorption Spectrometry. Weinheim, WILLEY-VCH,  Verlag GmbHCo. KGaA. 2005. 295 p.12. Gunduz S., Akman S. Determination of lead in rice grains by solid sampling HR-CS GFAAS // Food Chemistry. 2013. V. 141. P. 2634-2638.13. Simultaneous determination of Mo and Ni in wine and soil amendments by HR-CS GF AAS / W. Boschetti [et al.] // Anal. Methods. 2014. V. 6. P. 4247-4256.14. Determination of selenium in soil samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis / I.N.B. Castilho [et al.] // Anal. Methods. 2014. V. 6. P. 2870-2875.15. Comparison of three different sample preparation procedures for the determination of traffic-related elements in airborne particulate matter collected on glass fiber filters / I.N.B. Castilho [et al.] // Talanta. 2012. V. 88. P. 689-695.16. Solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry to monitor the biodistribution of gold nanoparticles in mice tissue after intravenous administration / M. Resano [et al.] // J. Anal. At. Spectrom. 2010. V. 25. P. 1864-1873.17. Аппаратно-программный комплекс для атомно-абсорбционной спектрометрии с многостадийной зондовой атомизацией / Ю.А. Захаров [и др.] // Научное приборостроение. 2013. Т. 23. №4. C. 104-111.18. Сайт Института геохимии им. А.П. Виноградова СО РАН [Электронный ресурс]: http://www.igc.irk.ru/Innovation/Standarts-obr/Catalog-2013.pdf (дата обращения: 01.07.2014).19. Пупышев А.А. Атомно-абсорбционный спектральный анализ. М.: Техносфера, 2009. 782 с.20. Slurry sampling for the determination of silver and gold in soils and sediments using electrothermal atomic absorption spectrometry / I. Lopez-Garcia [et al.] // Spectrochim. Acta. 2003. V. 58 B. P. 1715-1721.21. Разработка источника атомно-абсорбционного спектра для одновременного многоэлементного анализа / С.С. Курилко и [др.] // Материалы XIII Международного симпозиума «Применение анализаторов МАЭС в промышленности», Новосибирск, 2013. С. 40-50.22. Katskov D.A., Khanye G.E. Simultaneous Multi-Element Electrothermal Atomic Absorption Determination Using a Low Resolution CCD Spectrometer and Continuum Light Source: The Concept and Methodology // S. Afr. J. Chem. 2010. V. 63. P. 45-57.23. Gibson J., Katskov D.A. Simultaneous Determination of Metals in Coal with Low-Resolution Continuum Source Atomic Absorption Spectrometer and Filter Furnace Atomizer // S. Afr. J. Chem. 2011. V. 64. P. 79-87.24. Katskov D.A., Sadagov Yu.M. Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry// Spectrochim. Acta. 2011. V. 66B. P. 451-460.25. Kurfürst U. Solid Sample Analysis: Direct and Slurry Sampling Using GF-AAS and ETV-ICP. Berlin: Springer, 1998. 423 р.26. Slurry sampling for direct analysis of solid materials by electrothermal atomic absorption spectrometry (ETAAS). A literature review from 1990 to 2000 / M.J. Cal-Prieto et [al.] // Talanta. 2002. V. 56. P. 1-51.27. Концентрирование определяемых элементов на зонде в электротермическом атомизаторе / Ю.А. Захаров [и др.] // Журн. прикл. спектр. 2005. Т. 72, № 2. С. 256–259

Novel Azo-Dyes-Modified Isatin Derivatives: Synthesis, UV/VIS Spectroscopic, and Electrochemical Study

© 2016 Wiley-VHCA AG, ZürichA high-yield and simple synthesis of certain aminomethylisatins bearing dye fragments via the Mannich reaction of isatin with amino-containing azobenzenes was reported. It was found that the absence of electron-donating groups in azo-dye molecule prevents aminomethylation of isatin. The effect of the incorporation of an isatin moiety with an azobenzene dye in one molecule on its absorption and electrochemical behavior was studied using UV spectroscopy and cyclic voltammetry

Конденсация вторичных аминов с СН-кислотами и формальдегидом под действием микроволнового излучения

Objectives. To synthesize tertiary amines containing gem-dichlorocyclopropane or 1,3-dioxolane fragmentusing the Mannich reaction, as well as obtain ethyl ester of β-aminopropionic acidbydecarboxylation of tert-amine, a derivative of diethylmalonate containing a gem- dichlorocyclopropane fragment.Methods. In order to obtain tertiary amines by the Mannich reaction, the microwave activation method was used. To determine the qualitative and quantitative composition of the reaction masses, gas chromatography, electron ionization mass spectrometry, and 1H-, 13C-nuclear magnetic resonance spectrometry methodswere used.Results. Under microwave radiationconditions, tertiary amines containing gem- dichlorocyclopropane or 1,3-dioxolane fragment were synthesized by condensation of secondary amines, CH-acids, and paraformaldehyde.Conclusions. Tertiary amines containing a gem-dichlorocyclopropane or cycloacetal fragment in their structure were obtainedin high yields under microwave radiation.Цели. Синтезировать по реакции Манниха третичные амины, содержащие гем-дихлорциклопропановый или 1,3-диоксолановый фрагмент, а также получить этиловый эфир β-аминопропионовой кислоты декарбоксилированием трет-амина – производного диэтилмалоната, содержащего гем-дихлорциклопропановый фрагмент.Методы. Для получения третичных аминов по реакции Манниха был использован метод микроволной активации. Для определения качественного и количественного состава реакционных масс были использованы следующие методы анализа: газовая хроматография, масс-спектроскопия с электронной ионизацией, и 1H-, 13C-спектроскопия ядерного магнитного резонанса.Результаты. Третичные амины, содержащие гем-дихлорциклопропановый или 1,3-диоксолановый фрагмент, синтезированы конденсацией вторичных аминов, СН-кислот и параформальдегида в условиях микроволнового излучения.Выводы. С высокими выходами в условиях микроволнового излучения получены третичные амины, содержащие в своем строении гем-дихлорциклопропановый или циклоацетальный фрагмент

Unintentional high density p-type modulation doping of a GaAs/AlAs core-multi-shell nanowire

Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of considerable technological importance but remains a challenge due to the amphoteric behavior of the dopant atoms. Here we show that placing a narrow GaAs quantum well in the AlAs shell effectively getters residual carbon acceptors leading to an \emph{unintentional} p-type doping. Magneto-optical studies of such a GaAs/AlAs core multi-shell NW reveal quantum confined emission. Theoretical calculations of NW electronic structure confirm quantum confinement of carriers at the core/shell interface due to the presence of ionized carbon acceptors in the 1~nm GaAs layer in the shell. Micro-photoluminescence in high magnetic field shows a clear signature of avoided crossings of the $n=0$ Landau level emission line with the $n=2$ Landau level TO phonon replica. The coupling is caused by the resonant hole-phonon interaction, which points to a large 2D hole density in the structure.Comment: just published in Nano Letters (http://pubs.acs.org/doi/full/10.1021/nl500818k