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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Genetics of boron tolerance in durum wheat / by Sansanee Jamjod.

Jamjod, Sansanee January 1996 (has links)
Bibliography: leaves 234-256. / ix, 257 leaves, [12] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Genetic studies of tolerance of durum wheat (Triticum turgidum L. var durum) to high concentrations of boron (B) were undertaken to identify genetic variation in response to B, the mode of gene action, number of genes and chromosomal locations of genes controlling tolerance. Results demonstrated that tolerance to B is under simple genetic control as observed in bread wheat. High levels of tolerance can be transferred into sensitive commercial varieties via backcrossing and selection can be performed during seedling growth at early generations. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996
272

Conducting polymer nanocomposites loaded with nanotubes and fibers for electrical and thermal applications

Chiguma, Jasper. January 2009 (has links)
Thesis (Ph. D.)--State University of New York at Binghamton, Materials Science and Engineering Program, 2009. / Includes bibliographical references.
273

Investigations of hexagonal boron nitride: bulk crystals and atomically-thin two dimensional layers

Sperber, Jared L. January 1900 (has links)
Master of Science / Department of Chemical Engineering / James H. Edgar / Hexagonal boron nitride has been used as an inert, refractory material with excellent resistance to thermal decomposition and oxidation for more than fifty years. In the past few years, hBN has been targeted for potential electrical and optical devices such as neutron detectors, ultraviolet light emitters, deep ultraviolet light detectors, and substrates for graphene and other atomically-thin two-dimensional materials. All of these potential applications benefit from high quality, single crystals, with thicknesses varying from nanometers to microns. This research was undertaken to investigate four aspects of hBN crystal growth and recovery. (1) In an effort to optimize hBN crystal growth from a nickel-chromium flux, a series of stepped cooling experiments were undertaken. The temperature profile was stepped in a way as to promote growth in both the a and c directions, at their optimal growth conditions. Crystals were found to be typically 100-500 µm across and thickness of approximately 20-30 µm with a pyramid-like crystal habit. (2) A method for the removal of hBN crystals prior to freezing of the metal flux was demonstrated using a specialized hot pressed boron nitride crucible capable of removing hBN crystals from the flux in situ. (3) Growth of isotopically pure hBN crystals was undertaken. By modifying the crucible material for solution growth, enrichment of hBN crystals over 90% was accomplished. (4) Exfoliation of hBN has many potential applications, specifically as graphene-hBN heterostructures where layers approaching thicknesses of single atoms are most effective surface to interact with graphene as an electronic device. Several methods were tested toward exfoliating a single crystal resulting in few-layered hexagonal boron nitride nanosheets. As a result of these investigations a greater understanding of hBN bulk growth, its isotopic enrichment, its recovery, and its exfoliation was obtained.
274

Desenvolvimento do processo de deposicao eletroforetica de boro em substratos de aluminio destinados a construcao de detectores de neutrons

SAMPA, MARIA H. de O. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:32:32Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:09Z (GMT). No. of bitstreams: 1 03259.pdf: 2834364 bytes, checksum: fcbdf9e370a39ffdb27be573e65f253c (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
275

Desenvolvimento do processo de deposicao eletroforetica de boro em substratos de aluminio destinados a construcao de detectores de neutrons

SAMPA, MARIA H. de O. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:32:32Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:09Z (GMT). No. of bitstreams: 1 03259.pdf: 2834364 bytes, checksum: fcbdf9e370a39ffdb27be573e65f253c (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
276

Boron deficiency in the bean root

Thomas, Heather G. January 1965 (has links)
No description available.
277

The Study of Comprehensive Reinforcement Mechanism of Hexagonal Boron Nitride on Concrete

He, Qinyue 08 1900 (has links)
The addition of hexagonal boron nitride (h-BN) has introduced a comprehensive reinforcing effect to the mechanical and electrochemical properties of commercial concrete, including fiber reinforced concrete (FRC) and steel fiber reinforced concrete (SFRC). Although this has been proven effective and applicable, further investigation and study is still required to optimize the strengthen result which will involve the exfoliation of h-BN into single-layered nano sheet, improving the degree of dispersion and dispersion uniformity of h-BN into concrete matrix. There is currently no direct method to test the degree of dispersion of non-conductive particles, including h-BN, in concrete matrix, therefore it is necessary to obtain an analogous quantification method like SEM, etc. The reinforcing mechanism on concrete, including FRC and SFRC is now attracting a great number of interest thanks to the huge potential of application and vast demand across the world. This study briefly describes the reinforcing mechanism brought by h-BN. In this study, different samples under varied conditions were prepared according to the addition of h-BN and dispersant to build a parallel comparison. Characterization is mainly focused on their mechanical properties, corrosive performance and SEM analysis of the cross-section of post-failure samples.
278

Processing and Properties of 1D and 2D Boron Nitride Nanomaterials Reinforced Glass Composites / Processing and Properties of 1D and 2D Boron Nitride Nanomaterials Reinforced Glass Composites

Saggar, Richa January 2016 (has links)
Glasses and ceramics offer several unique characteristics over polymers or metals. However, they suffer from a shortcoming due to their brittle nature, falling short in terms of fracture toughness and mechanical strength. The aim of this work is to reinforce borosilicate glass matrix with reinforcements to increase the fracture toughness and strength of the glass. Boron nitride nanomaterials, i.e. nanotubes and nanosheets have been used as possible reinforcements for the borosilicate glass matrix. The tasks of the thesis are many fold which include: 1. Reinforcement of commercially derived and morphologically different (bamboo like and cylinder like) boron nitride nanotubes in borosilicate glass with the concentration of 0 wt%, 2.5 wt% and 5 wt% by ball milling process. Same process was repeated with reinforcing cleaned boron nitride nanotubes (after acid purification) into the borosilicate glass with similar concentrations. 2. Production of boron nitride nanosheets using liquid exfoliation technique to produce high quality and high aspect ratio nanosheets. These boron nitride nanosheets were reinforced in the borosilicate glass matrix with concentrations of 0 wt%, 2.5 wt% and 5 wt% by ball milling process. The samples were consolidated using spark plasma sintering. These composites were studied in details in terms of material analysis like thermo-gravimetric analysis, detailed scanning electron microscopy and transmission electron microscopy for the quality of reinforcements etc.; microstructure analysis which include the detailed study of the composite powder samples, the densities of bulk composite samples etc; mechanical properties which include fracture toughness, flexural strength, micro-hardness, Young’s modulus etc. and; tribological properties like scratch resistance and wear resistance. Cleaning process of boron nitride nanotubes lead to reduction in the Fe content (present in boron nitride nanotubes during their production as a catalyst) by ~54%. This leads to an improvement of ~30% of fracture toughness measured by chevron notch technique for 5 wt% boron nitride nanotubes reinforced borosilicate glass. It also contributed to the improvement of scratch resistance by ~26% for the 5 wt% boron nitride nanotubes reinforced borosilicate glass matrix. On the other hand, boron nitride nanosheets were successfully produced using liquid exfoliation technique with average length was ~0.5 µm and thickness of the nanosheets was between 4-30 layers. It accounted to an improvement of ~45% for both fracture toughness and flexural strength by reinforcing 5 wt% of boron nitride nanosheets. The wear rates reduced by ~3 times while the coefficient of friction was reduced by ~23% for 5 wt% boron nitride nanosheets reinforcements. Resulting improvements in fracture toughness and flexural strength in the composite materials were observed due to high interfacial bonding between the boron nitride nanomaterials and borosilicate glass matrix resulting in efficient load transfer. Several toughening and strengthening mechanisms like crack bridging, crack deflection and significant pull-out were observed in the matrix. It was also observed that the 2D reinforcement served as more promising candidate for reinforcements compared to 1D reinforcements. It was due to several geometrical advantages like high surface area, rougher surface morphology, and better hindrance in two dimensions rather than just one dimension in nanotubes.
279

Creative Synthesis of Novel Optically-Functional Materials by Modified BODIPYs with Unique Structures / 特殊構造BODIPYによる新寄光機能性材料の創出

Yamane, Honami 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20401号 / 工博第4338号 / 新制||工||1672(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 赤木 和夫, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
280

Synthesis of one-dimensional boron related nanostructures by chemical vapor deposition

Guo, Li 28 August 2008 (has links)
No description available.

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