Spin dynamics in high-mobility two-dimensional electron systems

Understanding the spin dynamics in semiconductor heterostructures is highly important for future semiconductor spintronic devices. In high-mobility two-dimensional electron systems (2DES), the spin lifetime strongly depends on the initial degree of spin polarization due to the electron-electron interaction. The Hartree-Fock (HF) term of the Coulomb interaction acts like an effective out-of-plane magnetic field and thus reduces the spin-flip rate. By time-resolved Faraday rotation (TRFR) techniques, we demonstrate that the spin lifetime is increased by an order of magnitude as the initial spin polarization degree is raised from the low-polarization limit to several percent. We perform control experiments to decouple the excitation density in the sample from the spin polarization degree and investigate the interplay of the internal HF field and an external perpendicular magnetic field. The lifetime of spins oriented in the plane of a [001]-grown 2DES is strongly anisotropic if the Rashba and Dresselhaus spin-orbit fields are of the same order of magnitude. This anisotropy, which stems from the interference of the Rashba and the Dresselhaus spin-orbit fields, is highly density-dependent: as the electron density is increased, the kubic Dresselhaus term becomes dominant and reduces the anisotropy.Comment: 13 pages, 6 figure

Preparation, Properties, and Microstructure of Graphite Powder-Containing Conductive Concrete

Conductive concrete not only retains the advantages of ordinary concrete but also possesses high electrical conductivity. It can be applied to snow and ice control on the roads. In preparing the conductive concrete, sand as the conductive fine aggregate was replaced with graphite powder. Its properties and microstructure were also investigated. The conductive concrete strength is shown to decrease with a graphite powder ratio. The conductive concrete resistivity goes down with the powder fineness and content; the temperature grows after electrification, and the concrete exhibits a high heating effect. Graphite powder exerts little influence on the hydration products of the concrete. With an increase in the content and fineness of graphite powder, its filling efficiency becomes rather helpful to form the conductive path.Проводящий бетон не только сохраняет преимущества обычного бетона, но и имеет высокую электропроводность; может использоваться для удаления снега и плавления льда на дорогах. Для получения такого бетона применялся вместо песка в качестве проводящего мелкого заполнителя графитовый порошок. Исследуются свойства и микроструктура бетона. Установлено, что прочность бетона уменьшается с увеличением содержания графитового порошка. Электрическое удельное сопротивление бетона уменьшается с увеличением мелкости и содержания графитового порошка; температура повышается после электризации, и бетон проявляет высокий нагревательный эффект. Графитовый порошок оказывает незначительное влияние на продукты гидратации проводящего бетона. С увеличением содержания и мелкости графитового порошка увеличивается положительный эффект заполнения графитовым порошком для формирования проводящей дорожки.Електропровідний бетон не тільки зберігає переваги звичайного бетону, але і має високу електропровідність; може використовуватися для видалення снігу та плавлення льоду на дорогах. Для отримання такого бетону застосовувався замість піску в якості провідного дрібний заповнювач графітовий порошок. Досліджуються властивості і мікроструктура бетону. Встановлено, що міцність бетону зменшується зі збільшенням вмісту графітового порошку. Електричний питомий опір бетону зменшується зі збільшенням дрібноту і змісту графітового порошку; температура підвищується після електризації, і бетон проявляє високий нагрівальний ефект. Графітовий порошок має незначний вплив на продукти гідратації проводить бетону. Зі збільшенням вмісту і дрібноту графітового порошку збільшується позитивний ефект заповнення графітовим порошком для формування провідної доріжк

Semileptonic decays of Bs1B_{s1}, Bs2∗B_{s2}^*, Bs0B_{s0} and Bs1′B_{s1}'

Stimulated by recent observations of the excited bottom-strange mesons $B_{s1}$ and $B_{s2}^*$, we calculate the semileptonic decays $B_{s0}, B_{s1}^{\prime}, B_{s1}, B_{s2}^*\to [D_s(1968), D_{s}^*(2112), D_{sJ}(2317), D_{sJ}(2460)]\ell\bar{\nu}$, which is relevant for the exploration of the potential of searching these semileptonic decays in experiment.Comment: 11 pages, 3 figures, 9 tables. More discussion added, some descriptions changed. The version to appear in EPJ

Light-cone QCD Sum Rules for the Λ\Lambda Baryon Electromagnetic Form Factors and its magnetic moment

We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the $\Lambda$ baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is $\mu_\Lambda=-(0.64\pm0.04)\mu_N$, which is in accordance with the experimental data and the existing theoretical results. We find that it is twist 4 but not the leading twist distribution amplitudes that dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.

Spin dynamics in semiconductors

This article reviews the current status of spin dynamics in semiconductors which has achieved a lot of progress in the past years due to the fast growing field of semiconductor spintronics. The primary focus is the theoretical and experimental developments of spin relaxation and dephasing in both spin precession in time domain and spin diffusion and transport in spacial domain. A fully microscopic many-body investigation on spin dynamics based on the kinetic spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published in Physics Reports

Fungal diversity notes 253–366: taxonomic and phylogenetic contributions to fungal taxa

Notes on 113 fungal taxa are compiled in this paper, including 11 new genera, 89 new species, one new subspecies, three new combinations and seven reference specimens. A wide geographic and taxonomic range of fungal taxa are detailed. In the Ascomycota the new genera Angustospora (Testudinaceae), Camporesia (Xylariaceae), Clematidis, Crassiparies (Pleosporales genera incertae sedis), Farasanispora, Longiostiolum (Pleosporales genera incertae sedis), Multilocularia (Parabambusicolaceae), Neophaeocryptopus (Dothideaceae), Parameliola (Pleosporales genera incertae sedis), and Towyspora (Lentitheciaceae) are introduced. Newly introduced species are Angustospora nilensis, Aniptodera aquibella, Annulohypoxylon albidiscum, Astrocystis thailandica, Camporesia sambuci, Clematidis italica, Colletotrichum menispermi, C. quinquefoliae, Comoclathris pimpinellae, Crassiparies quadrisporus, Cytospora salicicola, Diatrype thailandica, Dothiorella rhamni, Durotheca macrostroma, Farasanispora avicenniae, Halorosellinia rhizophorae, Humicola koreana, Hypoxylon lilloi, Kirschsteiniothelia tectonae, Lindgomyces okinawaensis, Longiostiolum tectonae, Lophiostoma pseudoarmatisporum, Moelleriella phukhiaoensis, M. pongdueatensis, Mucoharknessia anthoxanthi, Multilocularia bambusae, Multiseptospora thysanolaenae, Neophaeocryptopus cytisi, Ocellularia arachchigei, O. ratnapurensis, Ochronectria thailandica, Ophiocordyceps karstii, Parameliola acaciae, P. dimocarpi, Parastagonospora cumpignensis, Pseudodidymosphaeria phlei, Polyplosphaeria thailandica, Pseudolachnella brevifusiformis, Psiloglonium macrosporum, Rhabdodiscus albodenticulatus, Rosellinia chiangmaiensis, Saccothecium rubi, Seimatosporium pseudocornii, S. pseudorosae, Sigarispora ononidis and Towyspora aestuari. New combinations are provided for Eutiarosporella dactylidis (sexual morph described and illustrated) and Pseudocamarosporium pini. Descriptions, illustrations and / or reference specimens are designated for Aposphaeria corallinolutea, Cryptovalsa ampelina, Dothiorella vidmadera, Ophiocordyceps formosana, Petrakia echinata, Phragmoporthe conformis and Pseudocamarosporium pini. The new species of Basidiomycota are Agaricus coccyginus, A. luteofibrillosus, Amanita atrobrunnea, A. digitosa, A. gleocystidiosa, A. pyriformis, A. strobilipes, Bondarzewia tibetica, Cortinarius albosericeus, C. badioflavidus, C. dentigratus, C. duboisensis, C. fragrantissimus, C. roseobasilis, C. vinaceobrunneus, C. vinaceogrisescens, C. wahkiacus, Cyanoboletus hymenoglutinosus, Fomitiporia atlantica, F. subtilissima, Ganoderma wuzhishanensis, Inonotus shoreicola, Lactifluus armeniacus, L. ramipilosus, Leccinum indoaurantiacum, Musumecia alpina, M. sardoa, Russula amethystina subp. tengii and R. wangii are introduced. Descriptions, illustrations, notes and / or reference specimens are designated for Clarkeinda trachodes, Dentocorticium ussuricum, Galzinia longibasidia, Lentinus stuppeus and Leptocorticium tenellum. The other new genera, species new combinations are Anaeromyces robustus, Neocallimastix californiae and Piromyces finnis from Neocallimastigomycota, Phytophthora estuarina, P. rhizophorae, Salispina, S. intermedia, S. lobata and S. spinosa from Oomycota, and Absidia stercoraria, Gongronella orasabula, Mortierella calciphila, Mucor caatinguensis, M. koreanus, M. merdicola and Rhizopus koreanus in Zygomycota

Fertilizer requirements for wheat and maize in China: the QUEFTS approach

Wheat and maize are two major food crops in China. Conventional fertilizer recommendations result in higher than necessary costs to farmers and increased environmental pollution. It is essential to quantitatively estimate optimal fertilizer requirements to alleviate the problems of the two crops in China. The QUEFTS (QUantitative Evaluation of the Fertility of Tropical Soils) model was used to estimate region-specific nitrogen (N), phosphorus (P) and potassium (K) requirements as well as fertilizer applications needed to realize target yields of wheat and maize. Data of field experiments with different fertilization treatments of various regions in China during the years of 1985-1995 were used to calibrate the QUEFTS model for both wheat and maize. Minimum and maximum internal nutrient efficiencies (kg grain kg(-1)) for the model were estimated at N (25 and 56), P (171 and 367), K (24 and 67) for wheat, and N (21 and 64), P (126 and 384), K (20 and 90) for maize. The model suggested a linear increase of grain yields for scenarios with nutrient contents of 24.6, 3.7 and 23.0 kg N, P and K per 1000 kg of wheat grain and 25.8, 4.3 and 23.1 kg N, P and K per 1000 kg of maize grain. These results suggest that the average N: P: K ratio in the plant dry matter is about 6.7: 1: 6.2 for wheat and 6.0: 1: 5.4 for maize. Relationships between internal N, P and K levels and soil properties were established and relationships between the recovery efficiencies of applied fertilizer - N, P and K were found. Running the calibrated QUEFTS model with observed field data produced a good fit between predicted and observed data. It was concluded that the calibrated QUEFTS model could be a useful tool for improving fertilizer recommendations for wheat and maize in China