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

Usability of contaminated groundwater of the upper section in the reservoir pressure maintenance system (on the example of the Republic of Tatarstan)

More than 50-years exploitation of large oil fields in Tatarstan has led to substantial transformation of hydrogeoecological conditions at different levels of the section. The most dangerous of them is intense and bulk pollution of the fresh groundwater area with salt brines produced together with fresh water. In some parts of Romashkinskoye, Bavlynskoye and Novo-Elkhovskoye deposits share of underground water with high salinity (up to 5-10 g/dm 3 ), hardness (up to 40-70 mmol/dm 3 ) and the chloride concentration (more than 20%-mole) as a part of Lower Kazanian bearing complex, which is the most productive part of the section, can reach 60 %. Sometimes (for protection of the existing underground drinking water intake, elimination or localization of water pollution focus) the most optimal way to dispose contaminated water is their use in the reservoir pressure maintenance system. This may appear negative side effects such as scaling in oil horizons, wells and communication. The probability of calcium sulfate and calcium carbonate sediments, which are the commonest salts complicated oil production process in Tatarstan, was estimated on the basis of the analysis of underground water composition in the upper section (15 water samples of Lower Kazanian aquifer), water composition in oil-bearing horizon in the Devonian sequence (358 samples) and mixtures of underground water at different depths (465 virtual samples). It is shown that the most stable in respect of scale are mixtures with mineralization 68-104 g/dm 3 . For rapid determination of their resistance in respect of scaling regression connections are shown, their use is possible if there are data of mineralization, pH and also the concentrations of ions HCO 3 - , SO 4 2- , Ca 2+ in groundwater at different depths

The Scandinavians among the First Settlers of Novgorod on the Basis of Archaeological Evidence

The article deals with the problem of the cultural and ethnic characteristics of first settlers of Novgorod. The previous historiography is reviewed. The revision of the archaeological collections enabled to increase the number and categories of Scandinavian objects, while the Slavonic component remains unclear. The Scandinavians must have been among the founders of Novgorod already in 930–950 A. D. The pattern of distribution of the Scandinavian objects suggests a free resettlement of Norsemen in the town. The “Poromon courtyard” mentioned in the Primary Rus’ Chronicle cannot be regarded as a court of the overseas merchants. The Scandinavians in Novgorod were not directly connected to the ethno-social group of Rus’-Rhôs linked to the Ryurikids. The archaeologically attested end of the Varangian presence in the town was caused by the cessation of payment of tributum pacis to the Varangians after the death of Prince Yaroslav the Wise. The tradition of the Russian historiography to underestimate the participation of the Scandinavians in the early development of Novgorod is stemmed from the “auto-censorship” of the Stalinist period, turning later into “scholarly inertia”

Variations and conditions of the composition natural waters in the central european russia (On example of the Tatarstan republic)

© SGEM2017 All Rights Reserved. The upper part of the Tatarstan Republic section is complexed by sedimentary of multi facies complexes of Middle Upper Permian, Mesozoic and Pliocene-Quaternary rocks. The surface and ground water are characterized by a wide variability in composition, mineralization, water hardness and other parameters. These variations are determined by a complex of natural and technogenic factors. The most important natural factor is interaction of the atmospheric precipitation and their derivates with soils and rocks of the section. For assessment of this interaction, were analyzed water extracts and filtrates on the basis of distilled, snow melt and spring waters from the main types of soils and rocks. Additional determined the gradients of concentration changes by main parameters and components of the groundwater composition during their downward filtration in different regions of Tatarstan. The studies allows for predict hydrogeochemical conditions of active water exchange zone of cross section. First of all, this is necessary for the best location of water wells and efficient use of ground water

Features of Reaction of 2-(5-Methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-4H-benzo[e]-1,3,2-dioxaphosphorin-4-one with 1,2-Dicarbonyl Compounds

© 2018, Pleiades Publishing, Ltd. 2-(5-Methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-4H-benzo[e]-1,3,2-dioxaphosphorin-4-one reacts with perfluorodiacetyl, 3,6-di(tert-butyl)-1,2-benzoquinone and phenanthrenequinone only with the participation of a three-coordinated phosphorus atom to form spirophosphoranes containing acyclic 5-methyl-2- phenyl-2H-1,2,3-diazaphosphol-4-yl substituent, whereas the interaction with tetrachloro-1,2-benzoquinone proceeds via expanding the six-membered heterocycle to the nine-membered one to form 2-(2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-2,9-dioxo-4,5,6,7-tetrachlorodibenzo[d,h]-1,3,8-trioxaphosphonine

Survival of the prawn Macrobrachium tenellum (Smith, 1871) in confinement with the native fish Dormitator latifrons (Richardson, 1844)

Objective: The aim of this study was to test the survival of Macrobrachium tenellum in different confinement conditions with Dormitator latifrons. Design/methodology/approach: Using wild specimens acclimated to captive conditions of both species, three trials of different proportion were performed with treatments consisting in the presence/absence of food and shelters. Prawn/fish proportion for the assays were: 15/15 for T1, 15/3 for T2 and 10/3 for T3. In assays T1 and T2 juvenile prawns and fish were used, while in T3 post-larvae prawns and pre-juvenile fish were used. To test the survival with or without fed, it was schedule a four-day feeding ad libitum period, following by a two-day fed depravation period in all the assays. Results: In assays with juveniles of M. tenellum the survival rate was superior to 80% with or without shelter, when T1 showed 97-100% survival; meanwhile T3 presented a 56.67 % of survival, suggesting it’s necessary to use only juvenile prawns in co-culture systems. The use of shelters and fed deprivation had no significant effects on the survival of prawns. Limitations on study/implications: M. tenellum is an important aquatic resource for the central Mexican Pacific, region in which the D. latifrons is a representative native fish with a developing aquaculture. A polyculture or co-culture system with these species can accelerate the sustainability of both species productions. Findings/conclusions: The results suggest this polyculture system may be feasible, and longer duration culture are recommended.Objective: The aim of this study was to test the survival of Macrobrachium tenellum in different confinement conditions with Dormitator latifrons. Design/methodology/approach: Using wild specimens acclimated to captive conditions of both species, three trials of different proportion were performed with treatments consisting in the presence/absence of food and shelters. Prawn/fish proportion for the assays were: 15/15 for T1, 15/3 for T2 and 10/3 for T3. In assays T1 and T2 juvenile prawns and fish were used, while in T3 post-larvae prawns and pre-juvenile fish were used. To test the survival with or without fed, it was schedule a four-day feeding ad libitum period, following by a two-day fed depravation period in all the assays. Results: In assays with juveniles of M. tenellum the survival rate was superior to 80% with or without shelter, when T1 showed 97-100% survival; meanwhile T3 presented a 56.67 % of survival, suggesting it’s necessary to use only juvenile prawns in co-culture systems. The use of shelters and fed deprivation had no significant effects on the survival of prawns. Limitations on study/implications: M. tenellum is an important aquatic resource for the central Mexican Pacific, region in which the D. latifrons is a representative native fish with a developing aquaculture. A polyculture or co-culture system with these species can accelerate the sustainability of both species productions. Findings/conclusions: The results suggest this polyculture system may be feasible, and longer duration culture are recommended

EPR imaging study of paramagnetic centre distribution in thiokol-epoxy hermetics

The distribution of paramagnetic centres in carbon black filler in the interphase layer of the thiokol-epoxy hermetics on the border of brass or glass substrate was studied using EPR-imaging method. It was shown that the relative content of radicals decreases near the hermetic-"rigid" surface contact border. The thickness of the layer with a low concentration of radicals is estimated as 0.5±0.3 mm. The inhomogeneous distribution of radicals is more obvious in the case of hermetic hardening on a brass surface. These results are explained by a catalytic acceleration of the thiokol-epoxy polymerization reaction in the region of hermetic-metal surface contact. © 1996 Springer

The formation of secondary arylphosphines in the reaction of organonickel sigma-complex [NiBr(Mes)(bpy)], where Mes = 2,4,6-trimethylphenyl, bpy = 2,2′-bipyridine, with phenylphosphine

© 2016 Taylor & Francis Group, LLC.The reactivity of organonickel sigma-complex [NiBr(Mes)(bpy)], where Mes = 2,4,6-trimethylphenyl, bpy = 2,2’-bipyridine towards phenylphosphine (PhPH2) has been investigated. It was found that this interaction leads to secondary mesitylphenylphosphine and dimesitylphosphine by formation of new carbon-phosphorus bond involving mesityl fragment of starting organonickel sigma-complex

Biology and use of the Pacific fat sleeper Dormitator latifrons (Richardson, 1844): state of the art review

The present work is a review of the literature on the native Mexican fish Dormitator latifrons. The aim is to contribute to the integration and systematization of current knowledge to make it easier to identify existing knowledge gaps and breakthroghs Moreover, promote the successful cultivation and protection of this species whose consumption is increasing in Latin America. A review of the articles related to D. latifrons published in international and regional databases was carried out. The articles reviewed focus on taxonomy and systematics, phylogenetic, geographic distribution, ecology, physiology, reproduction, development, pathology, health, and the technologies used to cultivate this fish species. The conclusion is that, even though the cultivation of D. latifrons is of commercial interest in some countries, there are still significant gaps in our knowledge of biology and, consequently, the domestication potential of the species. Filling these gaps will require systematic research efforts on protecting natural populations and improving mass cultivation techniques.Fil: Vega Villasante, Fernando. Universidad de Guadalajara; MéxicoFil: Ruiz González, Luis E.. Universidad de Guadalajara; MéxicoFil: Chong Carrillo, Olimpia. Universidad de Guadalajara; MéxicoFil: Basto Rosales, Mao E. R.. Tecnológico Nacional de Bahía de Banderas; MéxicoFil: Palma Cancino, David J.. Universidad de Guadalajara; MéxicoFil: Tintos Gómez, Adrián. Universidad Tecnológica de Manzanillo; MéxicoFil: Montoya Martínez, Cynthia E.. Universidad de Guadalajara; MéxicoFil: Kelly Gutiérrez, Liza D.. Universidad de Guadalajara; MéxicoFil: Guerrero Galván, Saúl R.. Universidad de Guadalajara; MéxicoFil: Ponce Palafox, Jesús T.. Universidad Autónoma de Nayarit; MéxicoFil: Zapata, Ana. Universidad de Guadalajara; MéxicoFil: Musin, Gabriela Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Badillo Zapata, Daniel. Universidad de Guadalajara; Méxic