NaOsO3: A high Neel temperature 5d oxide

The origin of a high Neel temperature in a 5d oxide, NaOsO3, has been analyzed within the mean-field limit of a multiband Hubbard model and compared with the analogous 4d oxide, SrTcO3. Our analysis shows that there are a lot of similarities in both of these oxides on the dependence of the effective exchange interaction strength (J(0)) on the electron-electron interaction strength ( U). However, the relevant value of U in each system puts them in different portions of the parameter space. Although the Neel temperature for NaOsO3 is less than that for SrTcO3, our results suggest that there could be examples among other 5d oxides that have a higher Neel temperature. We have also examined the stability of the G-type antiferromagnetic state found in NaOsO3 as a function of electron doping within GGA + U calculations and find a robust G-type antiferromagnetic metallic state stabilized. The most surprising aspect of the doped results is the rigid bandlike evolution of the electronic structure, which indicates that the magnetism in NaOsO3 is not driven by Fermi surface nesting.

Combustion synthesized tetragonal ZrO2: Eu3+ nanophosphors: Structural and photoluminescence studies

Novel crystalline tetragonal ZrO2: Eu3+ phosphors were prepared by a facile and efficient low temperature solution combustion method at 400 +/- 10 degrees C using oxalyl dihydrazide (ODH) as fuel. The powder X-ray diffraction patterns and Rietveld confinement of as formed ZrO2: Eu3+ (1-11 mol%) confirmed the presence of body centered tetragonal phase. The crystallite size estimated from Scherrer's and W-H plots was found to be in the range of 7-17 nm. These results were in good agreement with transmission electron microscopy studies. The calculated microstrain in most of the planes indicated the presence of tensile stress along various planes of the particles. The observed space group (P4(2)/nmc) revealed the presence of cations in the 2b positions (0.75, 0.25, 0.25) and the anions in the 4d positions (0.25, 0.25, 0.45). The optical band gap energies estimated from Wood and Tauc's relation was found to be in the range 4.3-4.7 eV. Photoluminescence (PL) emission was recorded under 394 and 464 nm excitation shows an intense emission peak at 605 nm along with other emission peaks at 537, 592, 605 and 713 nm. These emission peaks were attributed to the transition of D-5(0) -> F-7(J) (J = 0, 1, 2, 3) of Eu3+ ions. The high ratio of Intensity of (D-5(0) -> F-7(2)) and (D-5(0) -> F-7(1)) infers that Eu3+ occupies sites with a low symmetry and without an inversion center. CIE color coordinates indicated the red regions which could meet the needs of illumination devices. (C) 2014 Elsevier B.V. All rights reserved.

Electronic structure and surface properties of SrBi2Ta2O9 and related oxides

The electronic structure of SrBi2Ta2O9 and related oxides such as SrBi2Nb2O9, Bi2WO6 and Bi3Ti4O12 have been calculated by the tight-binding method. In each case, the band gap is about 4.1 eV and the band edge states occur on the Bi-O layers and consist of mixed O p/Bi s states at the top of the valence band and Bi p states at the bottom of the conduction band. The main difference between the compounds is that Nb 5d and Ti 4d states in the Nb and Ti compounds lie lower than the Ta 6d states in the conduction band. The surface pinning levels are found to pin Schottky barriers 0.8 eV below the conduction band edge.

Efecto de la eliminación de hospederos sobre la dinámica poblacional de gusano rosado del algodonero Pectinophora gossypiella (Saunders) lepidoptera, Gelechidae en plan de erradicación

El presente trabajo es un análisis descriptivo preliminar, sobre las actividades llevadas acabo en el plan de erradicación y contención del gusano rosado del algodonero Pectinophora gossypiella (Saunders), el cual se llevó a cabo en la “Isla del Maiz” (Corn lsland). localizada en el Océano Atlántico, en la Región Autónoma Atlantíco Sur (RAAS) de la República de Nicaragua. El objetivo principal de este trabajo consistió en determinar el efecto de la eliminación de los hospederos principales del "Gusano Rosado”, que son : Algodón Silvestre (Gossypium barbadense), Higuerilla (Ricinus communis) y algunos hospederos alternos que interactúan sobra su biologia y dinámica Poblacional. Se ubicaron trampas DELTAS de PRISMA con feromonas, con el objetivo de capturar adultos machos de Pectinophora gossypiella (Saunders). Esta plaga es facilmente confundible con el falso Gusano Rosado Colombiano (Sacacioces piralis). Gusano rosado, es una plaga cuarentenada en Nicaragua y restos de países del área Centro Americana; este insecto vive en malvaceas silvestres y cultivadas, atacando órganos reproductivos (Botones florales, flores, bellotas y motas), provoca la destrucción de semillas y las fibras, a la vez que sus daños y residuos fecales pueden ser fuente de infestación de hongos y bacterias fitopatogenas. Se realizaron inspeccionas de manera visual en diferentes áreas de la Isla para ubicar los focos de los hospederos ya determinados y posteriormente eliminarlos de forma mecanico-quimica, aplicándole al herbicida TORDON -101 (Pichloran 2, 4•D) a los tocones cortados y en ocasiones arrancar las plantas de forma manual desde sus raices, esto en dependencia de las dimensiones del tallo y tamaño de la planta en la medida que fuese posible arrancarlo del suelo. De la eliminación mecanico-quimica efectuado sobre los hospederos alimenticios de la plaga ya determinados (Algodón Silvestre e Higuerilla), se puede promediar un 95% de plantas huespedes eliminadas, para ambas especies, durante todo el periodo que duro nuestro trabajo. De igual forma se instalaron un total de 100 trampas DELTAS distribuidas en 5 rutas procurando cubrir el 95 % del territorio de la Isla del Maiz. Producto del monitoreo y el alto indice de capturas de adultos machos efecto de la actividad confucionista de la feromona sexual ubicada en cada una de las trampas, utilizado como método de control y erradicación de la plaga, nos indicaron que la población de adultos de gusano rosado presentaba una reducción considerable; lo cual demuestra que la eliminación de los hospederos afecta eficazmente la dinámica poblacional de esta plaga.

O governo de Tibério e a difícil arte de suceder bons imperadores

Resumo: Neste artigo, propomo-nos a analisar o Governo do Imperador Romano Tibério, da forma como foi descrito por Dion Cássio Cocceiano na obra História Romana. Dion Cássio foi senador na passagem do II para o III século d.C. e sua narrativa nos chegou bastante fragmentada, reconstruída a partir dos excertos de Xifilino e Zonaras. A autoridade do Príncipe não era hereditária. Assim, tornavase necessário refazer os laços de patronato e amicitia no início de cada governo. E esta não era uma tarefa fácil, nem mesmo para Tibério que sucedeu o considerado bom Imperador Otávio Augusto.

A moeda como um discurso : uma análise das representações de Otávio, Cleópatra e Marco Antônio

Abstract: The present article discusses about the representation of Octavius, Mark Antony and Cleopatra in three coins, to reflect about how the ancient mintage contributed for these personages could shape their images to the populus romanus in general.

Properties of high k gate dielectric gadolinium oxide deposited on Si(100) by dual ion beam deposition (DIBD)

Gadolinium oxide thin films have been prepared on silicon (100) substrates with a low-energy dual ion-beam epitaxial technique. Substrate temperature was an important factor to affect the crystal structures and textures in an ion energy range of 100-500 eV. The films had a monoclinic Gd2O3 structure with preferred orientation ((4) over bar 02) at low substrate temperatures. When the substrate temperature was increased, the orientation turned to (202), and finally, the cubic structure appeared at the substrate temperature of 700 degreesC, which disagreed with the previous report because of the ion energy. The AES studies found that Gadolinium oxide shared Gd2O3 structures, although there were a lot of oxygen deficiencies in the films, and the XPS results confirmed this. AFM was also used to investigate the surface images of the samples. Finally, the electrical properties were presented. (C) 2004 Elsevier B.V. All rights reserved.

重庆地区滑坡与降雨关系的概率分析

详细分析了重庆地区几十年内的577个滑坡的降雨与滑坡的历史资料，并对重庆地区的水文地质条件作了较为详细的介绍，然后从滑坡的时间分布、滑坡与日降雨量及暴雨的关系、滑坡与降雨发生时间的比较、滑坡发生的前10d内有降雨的天数与连续降雨的天数的比较等方面详细研究了降雨与滑坡的关系，得出了几个有益的结论。研究结果表明：滑坡的活动强度与雨量的大小成正比，滑坡基本发生在降雨之后的4d内：暴雨与滑坡的关系很密切，降暴雨的当天发生滑坡的可能性很大；当选取3mm作为降雨开始入渗的界限时，如果连续3d有降雨那么滑坡发生的可能性相对来说会很大。

Infared observations of H II regions

Spectral data are presented, giving intensities of the Brackett ɤ (B₇) line at six positions in M 42 and of the Brackett ten through fourteen (B₁₀-B₁₄) lines plus the He 4d³D-3p³p⁰ line at three positions in M 42. Observations of the Brackett ɤ line are also given for the planetary nebulae NGC 7027 and IC 418. Brackett gamma is shown to exhibit an anomalous satellite line in NGC 7027. Broadband data are presented, giving intensities at effective wavelengths of 1.25 μ, 1.65 μ, 2.2 μ, 3.5 μ and 4.8 μ for three positions in M 42.

Comparisons with visual and radio data as well as 12 micron and 20 micron data are used to derive reddening, electron temperatures, and electron densities for M 42 and the two planetaries, as well as a helium abundance for M 42. A representative electron temperature of 8400°K ± 1000°K, an electron density of 1.5 ±0.1 x 10³ cm^-3 and a He/H number density ratio of 0.10 +0.10/-0.05 are derived for the central region of M 42. The electron temperature is found to increase slightly with distance from the Trapezium.

M 42 is shown to emit in excess of the predicted recombination radiation throughout the entire infrared spectrum. The variations in the excess with wavelength and with position are analyzed to determine which of several physical processes may be operating. The longer wavelength infrared excess is shown to be dominated by dust emission, while the shorter wavelength infrared excess is caused by dust scattering. The dust is shown to be larger than the average interstellar particle. A new feature of the Orion red star ORS-1 is found in that it appears to have a reflection nebula around it.

Hyperfine interactions and nuclear structure

An automatic experimental apparatus for perturbed angular correlation measurements, capable of incorporating Ge(Li) detectors as well as scintillation counters, has been constructed.

The gamma-gamma perturbed angular correlation technique has been used to measure magnetic dipole moments of several nuclear excited states in the osmium transition region. In addition, the hyperfine magnetic fields, experienced by nuclei of 'impurity' atoms embedded in ferromagnetic host lattices, have been determined for several '4d' and '5d' impurity atoms.

The following magnetic dipole moments were obtained in the osmium transition region μ_2⁺(¹⁹⁰Os) = 0.54 ± 0.06 nm μ_4⁺(¹⁹⁰Os) = 0.88 ± 0.48 nm μ_2⁺(¹⁹²Os) = 0.56 ± 0.08 nm μ_2⁺(¹⁹²Pt) = 0.56 ± 0.06 nm μ_2^+’(¹⁹²Pt) = 0.62 ± 0.14 nm.

These results are discussed in terms of three collective nuclear models; the cranking model, the rotation-vibration model and the pairing-plus-quadrupole model. The measurements are found to be in satisfactory agreement with collective descriptions of low lying nuclear states in this region.

The following hyperfine magnetic fields of 'impurities' in ferromagnetic hosts were determined; H_int(Cd Ni) = - (64.0 ± 0.8)kG H_int(Hg Fe) = - (440 ± 105)kG H_int(Hg Co) = - (370 ± 78)kG H_int(Hg Ni) = - (86 ± 22)kG H_int(Tl Fe) = - (185 ± 70)kG H_int(Tl Co) = - (90 ± 35)kG H_int(Ra Fe) = - (105 ± 20)kG H_int(Ra Co) = - (80 ± 16)kG H_int(Ra Ni) = - (30 ± 10)kG, where in H_int(AB); A is the impurity atom embedded in the host lattice B. No quantitative theory is available for comparison. However, these results are found to obey the general systematics displayed by these fields. Several mechanisms which may be responsible for the appearance of these fields are mentioned.

Finally, a theoretical expression for time-differential perturbed angular correlation measurement, which duplicates experimental conditions is developed and its importance in data analysis is discussed.

Two and Three Finger Caging of Polygons and Polyhedra

Multi-finger caging offers a rigorous and robust approach to robot grasping. This thesis provides several novel algorithms for caging polygons and polyhedra in two and three dimensions. Caging refers to a robotic grasp that does not necessarily immobilize an object, but prevents it from escaping to infinity. The first algorithm considers caging a polygon in two dimensions using two point fingers. The second algorithm extends the first to three dimensions. The third algorithm considers caging a convex polygon in two dimensions using three point fingers, and considers robustness of this cage to variations in the relative positions of the fingers.

This thesis describes an algorithm for finding all two-finger cage formations of planar polygonal objects based on a contact-space formulation. It shows that two-finger cages have several useful properties in contact space. First, the critical points of the cage representation in the hand’s configuration space appear as critical points of the inter-finger distance function in contact space. Second, these critical points can be graphically characterized directly on the object’s boundary. Third, contact space admits a natural rectangular decomposition such that all critical points lie on the rectangle boundaries, and the sublevel sets of contact space and free space are topologically equivalent. These properties lead to a caging graph that can be readily constructed in contact space. Starting from a desired immobilizing grasp of a polygonal object, the caging graph is searched for the minimal, intermediate, and maximal caging regions surrounding the immobilizing grasp. An example constructed from real-world data illustrates and validates the method.

A second algorithm is developed for finding caging formations of a 3D polyhedron for two point fingers using a lower dimensional contact-space formulation. Results from the two-dimensional algorithm are extended to three dimension. Critical points of the inter-finger distance function are shown to be identical to the critical points of the cage. A decomposition of contact space into 4D regions having useful properties is demonstrated. A geometric analysis of the critical points of the inter-finger distance function results in a catalog of grasps in which the cages change topology, leading to a simple test to classify critical points. With these properties established, the search algorithm from the two-dimensional case may be applied to the three-dimensional problem. An implemented example demonstrates the method.

This thesis also presents a study of cages of convex polygonal objects using three point fingers. It considers a three-parameter model of the relative position of the fingers, which gives complete generality for three point fingers in the plane. It analyzes robustness of caging grasps to variations in the relative position of the fingers without breaking the cage. Using a simple decomposition of free space around the polygon, we present an algorithm which gives all caging placements of the fingers and a characterization of the robustness of these cages.

DIFFERENTIAL GEOMETRICAL METHODS IN THE STUDY OF OPTICAL-TRANSMISSION (SCALAR THEORY) .2. TIME-DEPENDENT TRANSMISSION THEORY

By generalization of the methods presented in Part I of the study [J. Opt. Soc. Am. A 12, 600 (1994)] to the four-dimensional (4D) Riemannian manifold case, the time-dependent behavior of light transmitting in a medium is investigated theoretically by the geodesic equation and curvature in a 4D manifold. In addition, the field equation is restudied, and the 4D conserved current of the optical fluid and its conservation equation are derived and applied to deduce the time-dependent general refractive index. On this basis the forces acting on the fluid are dynamically analyzed and the self-consistency analysis is given.

Conservação in vitro de germoplasma de Petiveria alliacea L. utilizando cultura de tecidos e criopreservação

A implementação de estratégias visando à conservação de espécies medicinais apresenta grande importância, tanto do ponto de vista ecológico quanto econômico. Petiveria alliacea L., espécie da família Phytolacaceae, conhecida como guiné, erva-de alho, erva-tipi ou amansa-senhor, pode ser encontrada desde a América Central até a América do Sul. Esta espécie possui ampla utilização medicinal, devido à presença, em sua composição, de vários polissulfetos, como o DTS (dibenziltrissulfeto), com propriedades antifúngica, antineoplásica e imunomodulatória, entre outras. O objetivo deste trabalho foi a conservação in vitro de germoplasma de Petiveria alliacea obtido de diferentes populações ocorrentes no Rio de Janeiro, através de métodos baseados em cultura de tecidos e criopreservação. Plantas obtidas através da germinação in vitro foram utilizadas como matrizes para a micropropagação através da multiplicação de meristemas pré-existentes em meio MS sem reguladores de crescimento, e embriões somáticos foram obtidos de forma direta a partir da cultura de explantes foliares das linhagens estudadas (Magé MG; Marechal Hermes MH; Niterói NT; Vila Isabel VI e Planta envasada AL), em presença de PIC (20μM) e 2,4D (22,6 μM), após 60 dias de cultivo. Os ápices caulinares das plantas micropropagadas e os embriões somáticos obtidos foram submetidos à criopreservação através de técnicas de vitrificação, encapsulamento-vitrificação e encapsulamento-desidratação, com a avaliação da pré-cultura e de soluções crioprotetoras (PVS2 e PVS3), em diferentes concentrações e tempos de exposição. Os resultados mostraram uma taxa de 100% de germinação in vitro. As condições para a pré-cultura de ápices foram padronizadas, entretanto não foram obtidos resultados positivos após o descongelamento. Por outro lado, os embriões da linhagem AL (linhagem embriogênica em cultura há 24 meses) mantiveram sua capacidade multiplicativa (100%) (embriogênese secundária) quando submetidos à desidratação em sacarose (0,5M) e expostos às soluções de vitrificação PVS2 e PVS3 pelos menores tempos (15 e 30 minutos). Os diferentes meios de recuperação apresentaram respostas variáveis em relação à capacidade multiplicativa dos embriões. O encapsulamento/vitrificação foi a técnica que promoveu maior tolerância dos embriões ao congelamento. A recuperação dos embriões através de multiplicação após a criopreservação abre uma perspectiva de conservação de genótipos com alta produção de polissulfetos, de interesse para a indústria farmacêutica

运用减法杂交、差异筛选与信使RNA差别显示聚合酶链式反应克隆冬小麦春化相关基因

对于某些一年生或二年生高等植物，春化作用是诱导其成花的一个重要的环境因子。冬小麦春化进程中存在着一个核酸代谢的关键期，利用分子生物学技术分离特异表达的基因是研究春化诱导成花机理的一个突破口。 利用TRIzol试剂快速提取冬小麦燕大1817(Triticum aestivum L. cv Yanda 1817)未春化、春化4d、春化20d、5d脱春化的胚芽中的总RNA，去除污染的DNA后，将引物P_1(5'TTTTTTTTTTTCA3')、P_2(5'TTTTTTTTTTCC3')与10个碱基的随机引物OPF_1-OPF_(20)、OPG_1-OPG_(20)组成80个引物对，对不同来源的RNA进行差别显示，共显示了大约10,000种mRNA，结果发现了两个仅在春化20d这一关键期表达而在未春化、春化4d、5d脱春化时不表达的春化相关基因(VRG)VRG49与VRG54。Northern分析进一步表明这两个基因仅与春化20d的冬小麦RNA有杂交信号。将VRG49与VRG54亚克隆于pGEM-4Z载体上，利用T_7测序系统获得了VRG49和VRG54的DNA序列，它们的长度分别为307bp与169bp。 春化21d的冬小麦京冬1号(T. aestivum L. cv Jingdong No. 1)胚芽的mRNA在逆转酶作用下反转录成sscDNA杂交，将过量的未春化、脱春化的mRNA与sscDNA杂交，运用磁珠法分离出未杂交上的sscDNA，以特异的sscDNA为模板，用DNA聚合酷I合成了dscDNA。通过对dscDNA内部EcoRI位点的甲基化、末端补平、EcoRI接头的安装、连接进入λgt10载体的EcoRI位置，以及运用包装系统进行体外包装，建立了库容为4 * 10~6pfu的富集低温诱导的冬小麦cDNA噬菌体文库。用来源于未春化、春化21d、脱春化的冬小麦mRNA合成3种cDNA探针，对噬菌斑进行原位杂交，结果筛选出了3个春化相关基因(VRG)VRG79、VRG111和VRG231。Dot blotting与Northern分析表明VRG79仅在冬小麦春化关键期21d表达。运用PCR方法从λgt10DNA中扩增出VRG79片断并亚克隆于PUC18载体上，通过T_7测序系统获得了VGR79的序列，其包括349个碱基。 通过Internet将VRG49、VRG54、VRG79与GenBank、EMBL、DDBJ、PBD中的序列进行同源性分析，结果发现这些基因至少是在植物中新发现的基因，对这些基因推测的一些功能也进行了讨论。

组织培养产生小麦族属间易位和其它染色体变异的分子细胞遗传学分析

组织培养能够诱导染色体断裂和重接进而产生染色体易位的观点已被广泛认识。大量的研究注意到了组织培养产生的核型不稳定性，其中大多数研究的对象是栽培作物及其属间或种间杂种幼胚和幼穗再生植株。借助于减数分裂分析、染色体分带和其它检测技术，在再生植株中发现了包括易位在内的许多染色体变异。可以相信，除了传统的同源和部分同源染色体配对时的自发易位和辐射诱变等方法以外，远缘杂种组织培养有可能作为产生染色体易位的又一种选择。尽管如此，至今还没有取得培养细胞中染色体易位的直接证据。本研究以普通小麦×硬粒小麦-簇毛麦双二倍体杂种为材料，研究了组织培养过程中离体细胞的染色体变异，用基因组原位杂交技术（GISH）证实组织培养诱导小麦染色体与簇毛麦染色体发生易位。同时，研究了小麦×黑麦杂种培养细胞中的染色体变异和黑麦B-染色体的变化。利用组织培养技术获得了小麦-黑麦和小麦-长穗偃麦草代换系和附加系。 1 普通小麦比较容易与硬粒小麦-簇毛麦双二倍体TH_1和TH_1W杂交，所选的9个普通小麦品种或品系与TH_1和TH_1W配制的19个杂交组合，平均结实率为46.7%，共计获得19个杂交组合2316粒杂种种子。正反交结果表明，以普通小麦为母本的杂交结实率高于反交结实率。在继代培养过程中，杂种幼胚愈伤组织生长迅速，甚至直接诱导出绿苗，共获得不同杂交组合2005株再生植株。 2 普通小麦与硬粒小麦-簇毛麦双二倍体杂种愈伤组织发生了比较大范围的染色体数目和结构变异。在检查的中国春×TH_1W、TH_1W×84加7911515、TH_1×84加7911515、TH_1W×91E27、鲁资357×TH_1W等5个杂种组合的1730个愈伤组织细胞中，平均有19.1%的细胞发生了染色体数目变异，不同杂交组合变化在12.7%（中国春×TH_1W）至30.7%（TH_1×84加7911515），其中，以染色体数目减少的变异为主，数目增加的变异比较少。杂种愈伤组织平均有6.3%的细胞发生了染色体断裂，产生染色体断片、环状染色体、端着丝点染色体和缺失染色体。断裂的染色体可能重新融合在一起，形成双着丝点染色体。 3 培养时间影响普通小麦×硬粒小麦-簇毛麦双二倍体和普通小麦×黑麦杂种愈伤组织细胞中的染色体数目和结构变异。在一定时间里，随着培养时间的延长，未发生核型变异的细胞逐渐减少，发生变异的细胞逐渐增多，主要表现在染色体数目减少的细胞增多，而染色体数目增加的细胞有减少的趋势。在长时间培养（190日龄）的愈伤组织中染色体加倍的细胞消失了，表明长时间培养对高倍性的细胞具有不利的选择，使这类细胞难以在长期继代培养中生存下去。愈伤组织在第一次继代培养时就发现有核型变异，说明染色体变异在愈伤组织培养初期就可以发生。 4 以簇毛麦总基因组DNA为探针，采用荧光原位杂交技术在普通小麦×硬粒小麦-簇毛麦双二倍体杂种愈伤组织细胞中发现小麦染色体与簇毛麦染色体发性易位，这一结果是组织培养诱导培养细胞中属间染色体易位的第一个直观的证据。易位的染色体既有臂间易位，也有小片段易位。易位的染色体不仅可以在愈伤组织细胞中存在，也能够在再生植株中表达。在64株中国春×TH_1W和NPFP×TH_1再生植株中，观察到了3个易位株，其中1个易位株是一个小麦染色体与一个簇毛麦染色体发生了相互易位，易位的簇毛麦染色体片段比较小，大约为簇毛麦染色体臂的1/2，而易位的小麦染色体大约是臂长的1/3，另外2个易位株染色体断点位于或靠近着丝点。本研究的结果再次证实了利用组织培养能够创造小麦与外源染色体之间发生易位。 5 ~(60)Co γ-射线辐射处理对于普通小麦中国春与硬粒小麦-簇毛麦双二倍体TH_1W杂种愈伤组织细胞的染色体变异有很大的影响。表现在未发生变异的细胞大大减少，发生染色体数目变异的细胞急剧增加，主要是染色体数目减少的变异提高了21.3%，相反染色体增加的变异不但没有增加，而且还有所减少。经过辐射处理的愈伤组织细胞染色体结构变异也有大幅度增加，变异频率提高，变异类型增加。发生染色体断裂和重接形成双着丝点染色体的细胞频率达到22.3%，比对照提高13.9%。辐射诱变对培养细胞中簇毛麦染色体变异发生明显的影响。与此同时，簇毛麦染色体与小麦染色体易位频率比对照提高了近2倍。观察结果还表明愈伤组织辐射处理比延长培养时间诱导染色体变异的效果更好。 6 尽管愈伤组织中发生的染色体变异在再生植株中多有发现，但是，只有比较小范围染色体变异的愈伤组织细胞具有再生能力形成再生植株，那些发生剧烈变异的细胞通常不具有再生能力，因而不能在再生植株中得到表达。普通小麦与硬粒小麦-簇毛麦双二倍体杂种大多数再生植株染色体数目与供体杂种保持一致，只有少数植株发生染色体数目变异。显然，发生较大染色体变异的愈伤组织细胞在增殖和分化过程中处于不利的地位，逐渐被淘汰。 7 在普通小麦与硬粒小麦-簇毛麦与黑麦杂种愈伤组织中，观察到相当高频率的染色体加倍细胞，为利用组织培养创造双二倍体提供了一种可能。但是，加倍的细胞只是培养初期的愈伤组织中出现，经过一段时间的培养，这种细胞大多消失了。而且，大多数再生植株染色体数目未发生加倍，其中并没有出现期望的双二倍体植株。表明加倍了的细胞在愈伤组织生长和分化过程中大范围变异的细胞一样受到不利的选择，再生能力比较差。因此，利用组织培养创造双二倍体需要更大的努力。 8 一些黑麦品种含有数目不等的B-染色体。B-染色体的多少对普通小麦与黑麦的杂交结实率有比较大的影响，数目越多，杂交结实率越低。在培养初期的愈伤组织细胞中，B-染色体的频率很高，例如69%的中国春×芬7416杂种的40日龄愈伤组织细胞中含有数目不等的B-染色体。常染色体的倍性影响B-染色体的分布，染色体数目加倍的双二倍体细胞中含多数B-染色体的细胞频率大大高于单倍体细胞。经过一段时间的培养之后，绝大多数B-染色体都不存在了，只有极少数细胞含有1个B-染色体。可能的原因是离体培养过程对B-染色体产生了不利的选择。 9 利用组织培养技术，从普通小麦与八倍体小黑麦杂种幼胚再生植株自交后代中选育出2个异代换系，从4D缺体小麦×八倍体小黑麦再生植株回交后代中选育出1个附加系。荧光原位杂交、C-分带和种子贮藏蛋白分析证明这两个代换系1D/1R代换，附加的也是1R染色体。从4D缺体小麦与八倍体小偃麦杂种再生植株自交和回交后代中选育出5个代换系和2个附加系。染色体配对和RAPD分析证实了长穗偃麦草染色质的存在。其中一些小麦-长穗偃麦草代换系和附加系对叶锈病免疫或高抗，对条锈病的一些生理小种和白粉病具有比较高的抗性。而且，附加系924和代换系807蛋白质含量分别达到19.32%和18.83%。 10 当普通小麦鲁资357与硬粒小麦-簇毛麦双二倍体杂交时，无论是实生苗还是再生植株都发生杂种致死现象。细胞学观察没有发现植株染色体发生变异，荧光原位杂交表明簇毛麦染色也没有发生可见的变异。推测这种杂种致死现象是由于鲁资357和硬粒小麦81086A（TH_1和TH_1W的硬粒小麦亲本）中可能分别带有互补的杂种致死基因所致。