Gene conservation - in situ, ex situ and sampling strategies.

Gene conservation of native conifer species in British Columbia is considered necessary primarily to safeguard the future evolutionary potential of species to climate change, new biotic challenges and for commercial genetic improvement programs. The tactical options include: (i) maintaining existing protected areas, (ii) creating new reserves for in situ management, and (iii) ex situ collections of various types.A two-part strategy is presented, with emphasis on technical justifications, for the conservation of conifer tree genetic resources of 23 British Columbia species. Part I is a survey of the frequency of each species in current land reserves in BC. Part II outlines an approach that will aid in setting priorities for additional gene conservation activities for specific species. This process attempts to use information on: (i) levels of in situ protection, (ii) the status of each species in current provenance research and breeding programs, and (iii) the relative capabilities for natural regeneration for each species.Representation of the 23 native conifer species in the current network of protected areas is generally complete. For instance, western hemlock is under little threat, as extensive ex situ collections are in field tests; it is well protected in the current reserve network, and it has a great capacity for natural regeneration. At the other extreme, whitebark pine has no ex situ collections made to date, needs additional protection in some ecoregions of the province, and generally has poor natural regeneration potential. While implementation of our strategy will be an ongoing process (i.e. updating information from both new and old in situ reserves, and setting new priorities among species), several immediate issues have been noted. These include; (i) follow-up work in the area of population sampling for ex situ collections, (ii) "ground truthing" of current reserves where data are weak, and (iii) examining the merit of certain populations not located in BC (as they could be as important as those currently protected in BC).For the future, various broad management questions will need to be resolved, such as: (i) whether existing reserves will perpetuate the various gene pools, and what management will be appropriate for such areas, (ii) the impact of pollen migration from genetically improved production stands on reserve stands, and (iii) the role of commercially improved stands and the breeding populations themselves to meet gene conservation objectives. Key words: gene conservation, native conifers, British Columbia, tree genetics

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Tree species of concern in New Brunswick, Canada. II. Guidelines for conservation of genetic resources

The Forestry Chronicle ◽

10.5558/tfc83402-3 ◽

2007 ◽

Vol 83 (3) ◽

pp. 402-407

Author(s):

J A Loo ◽

T L Beardmore ◽

J D Simpson ◽

D A McPhee

Keyword(s):

New Brunswick ◽

Genetic Resources ◽

Tree Species ◽

Ex Situ Conservation ◽

Ex Situ ◽

Gene Conservation ◽

American Beech ◽

Bur Oak ◽

Butternut Canker

Guidelines were developed by the New Brunswick Forest Gene Conservation Working Group for conserving genetic resources of four native tree species in New Brunswick. Gene conservation guidelines for three of these species aim to maintain sufficient gene pools of known or putatively resistant stock to retain or develop the potential for restoration. Natural populations of American beech (Fagus grandifolia) are known to have genotypes resistant to the beech scale at low frequencies. Gene conservation approaches include in situ and ex situ measures, including resistance breeding. White elm (Ulmus americana) demonstrates a degree of resistance to Dutch elm disease (DED), and will benefit from a mixture of in situ and ex situ conservation measures. Resistance to butternut canker has not yet been demonstrated in populations of butternut (Juglans cinerea), but ex situ conservation of putatively resistant genotypes will be of increasing importance as the frequency of butternut canker escalates. Bur oak (Quercus macrocarpa), threatened by small population size, habitat loss, and ongoing development, requires primarily in situ conservation and restoration efforts. Key words: American beech, bur oak, butternut, disease resistance, ex situ, gene conservation guidelines, genetic resources, in situ, restoration, white elm

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An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010648x ◽

1988 ◽

Vol 46 ◽

pp. 884-885

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove ◽

R. T. Tung

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Defect Density ◽

High Vacuum ◽

Ultra High Vacuum ◽

Ex Situ ◽

Metal Base ◽

In Situ Experiments ◽

Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

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The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150046 ◽

1993 ◽

Vol 51 ◽

pp. 842-843

Author(s):

K. Barmak

Keyword(s):

Thin Film ◽

Thin Films ◽

Phase Transformations ◽

Analytical Electron Microscopy ◽

Ex Situ ◽

Multilayer Thin Films ◽

Absolute Concentration ◽

Analytical Electron ◽

Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

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Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154287 ◽

1989 ◽

Vol 47 ◽

pp. 462-463

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Electron Diffraction ◽

High Vacuum ◽

High Energy ◽

Energy Electron ◽

Ultra High Vacuum ◽

Ex Situ ◽

Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

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Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

10.26434/chemrxiv.5459653 ◽

2017 ◽

Author(s):

Younghee Lee ◽

Daniela M. Piper ◽

Andrew S. Cavanagh ◽

Matthias J. Young ◽

Se-Hee Lee ◽

...

Keyword(s):

Lithium Ion ◽

Atomic Layer ◽

Mass Gain ◽

Alloy Film ◽

Ex Situ ◽

X Ray ◽

Layer Deposition ◽

Ion Conducting ◽

Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF3)(LiF)x alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm2 cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH3)3 as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm2 cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF3 and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF3)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF3)(LiF)x alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF3)(LiF)x alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF3)(LiF)x alloy film was measured as σ = 7.5 × 10-6 S/cm.</div>

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A New Method of Wafer Level Plan View TEM Sample Preparation by DualBeam

ISTFA 2008: Conference Proceedings from the 34th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2008p0168 ◽

2008 ◽

Author(s):

Hyoung H. Kang ◽

Michael A. Gribelyuk ◽

Oliver D. Patterson ◽

Steven B. Herschbein ◽

Corey Senowitz

Keyword(s):

Sample Preparation ◽

Ex Situ ◽

Wafer Level ◽

Cross Sectional ◽

Plan View ◽

Manufacturing Line ◽

Transmission Electron ◽

Thin Lamella ◽

Preparation Techniques

Abstract Cross-sectional style transmission electron microscopy (TEM) sample preparation techniques by DualBeam (SEM/FIB) systems are widely used in both laboratory and manufacturing lines with either in-situ or ex-situ lift out methods. By contrast, however, the plan view TEM sample has only been prepared in the laboratory environment, and only after breaking the wafer. This paper introduces a novel methodology for in-line, plan view TEM sample preparation at the 300mm wafer level that does not require breaking the wafer. It also presents the benefit of the technique on electrically short defects. The methodology of thin lamella TEM sample preparation for plan view work in two different tool configurations is also presented. The detailed procedure of thin lamella sample preparation is also described. In-line, full wafer plan view (S)TEM provides a quick turn around solution for defect analysis in the manufacturing line.

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PROPUESTA DE CONSERVACIÓN DE TRES ESPECIES MEXICANAS DE PICEA EN PELIGRO DE EXTINCIÓN

Revista Fitotecnia Mexicana ◽

10.35196/rfm.2015.3.235 ◽

2015 ◽

Vol 38 (3) ◽

pp. 235 ◽

Cited By ~ 1

Author(s):

Eduardo Mendoza-Maya ◽

Judith Espino-Espino ◽

Carmen Z. Quiñones-Pérez ◽

Celestino Flores-López ◽

Christian Wehenkel ◽

...

Keyword(s):

Ex Situ

Picea mexicana Martínez, P. chihuahuana Martínez y P. martinezii Patterson son especies endémicas de México en peligro de extinción. Se presenta una síntesis de su situación actual y una propuesta de manejo para su conservación in situ y ex situ, con base en la diversidad y estructura genética de las poblaciones y la ubicación de las áreas en donde se predice existirá el hábitat climático que les es propicio en el futuro (años 2030, 2060 y 2090; al promediar los modelos Canadiense, Hadley y Geofísica de Fluidos con escenarios de emisiones A y B). Para la conservación in situ se plantea la protección, el incremento de la diversidad genética y la expansión de las tres únicas poblaciones de P. mexicana, las cuatro únicas de P. martinezii y ocho poblaciones designadas prioritarias de las 40 poblaciones de P. chihuahuana, mediante la plantación de individuos originados de otras poblaciones hasta alcanzar un tamaño mínimo de población genéticamente viable (entre 1035 a 3836 individuos). Para la conservación ex situ se propone el establecimiento de poblaciones en sitios fuera del rango de distribución natural de las especies, en donde se ha proyectado que ocurrirá el clima que les es propicio, con al menos 3606 individuos de P. mexicana en el volcán Cofre de Perote, Veracruz; 2431 individuos de P. chihuahuana en el municipio de Guanaceví, Durango; y 3092 individuos de P. martinezii en la región de Tlatlauquitepec, Puebla, con plantas originadas de una mezcla de semillas colectadas de árboles al azar de poblaciones específicas.

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Hot Workability of 300M Steel Investigated by In Situ and Ex Situ Compression Tests

Metals ◽

10.3390/met9080880 ◽

2019 ◽

Vol 9 (8) ◽

pp. 880 ◽

Cited By ~ 2

Author(s):

Rongchuang Chen ◽

Haifeng Xiao ◽

Min Wang ◽

Jianjun Li

Keyword(s):

Flow Stress ◽

Strain Rate ◽

Hot Working ◽

Ex Situ ◽

Lower Strain Rate ◽

Hot Workability ◽

Compression Tests ◽

300M Steel ◽

Lower Strain

In this work, hot compression experiments of 300M steel were performed at 900–1150 °C and 0.01–10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

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