使用三脚式建筑块建造巨型树枝状树木
Jaime Ruiz1, Gustavo Lafuente, Sylvia Marcen
1Laboratoire de Chimie Organique et Organométallique, UMR CNRS No. 5802, Université Bordeaux I, 33405 Talence Cedex, France.
Journal of the American Chemical Society
|June 12, 2003
概括
巨大的有机树突被合成到第九代使用一种新的分离方法. 这些高度分支的结构超过了包装限制,这表明内部分支折叠可能会限制进一步的生长.
科学领域:
- 材料科学 材料科学 材料科学
- 有机化学 有机化学
- 聚合物化学 聚合物化学
背景情况:
- 体是高度分支的大分子,具有独特的特性.
- 有机树状体为高级应用提供可调节的特性.
- 在树枝状分子合成中实现高代,带来了重大挑战.
研究的目的:
- 为了合成巨大的溶性有机树脂.
- 探索一个新的分离的施工方法,直到第九代 (G(9)).
- 描述这些高一代树突体的结构完整性和特性.
主要方法:
- 采用水化-核替代序列的分离合成.
- 使用核磁共振 (NMR) 光谱学进行反应监测 ((1) H, (13) C, (29) Si).
- 通过矩阵辅助激光溶解/电离飞行时间 (MALDI TOF) 质谱,尺寸排除色谱 (SEC),高分辨率传输电子显微镜 (HRTEM) 和原子力显微镜 (AFM) 进行表征.
主要成果:
- 成功合成高达G(9) 的有机树突分子,通过NMR确认了清洁反应.
- MALDI TOF和SEC证实了下一代 (G(1) -G(5) 的单分散性 (1.00-1.02).
- HRTEM和AFM显示高一代的预期尺寸进展和球形形状,G(9) 超过10(5) 终端分支,超过密集包装限制.
结论:
- 这种新的分离方法使得能够合成异常大的有机树枝状物.
- G(9) 树突显著超过了理论上的密集包装极限,表明内部分支折叠.
- 内部树突反应被认为是这些高度密集的树突结构进一步增长的限制因素.
相关概念视频
Introduction to Wood
Wood, derived from trees, is a versatile and widely used construction material. Trees feature a trunk surrounded by a protective layer of dead bark. Beneath this outer layer lies the living bark, followed by the cambium, and then the sapwood which transitions into heartwood as it matures. At the center of the trunk is the pith. The age of a tree can be discerned by examining its growth rings, which are concentric bands visible in the trunk's cross-section.
The structural integrity of the wood...
The structural integrity of the wood...
Softwoods and Hardwoods
Softwoods and hardwoods, derived from different types of trees, are distinguished by their leaf structures and cellular compositions, each serving unique purposes in construction and manufacturing. Softwoods come from cone-bearing trees with needle-like leaves and are predominantly composed of longitudinal cells called tracheids and a smaller proportion of radial cells known as rays. Due to their cellular structure, softwoods are commonly used in construction for structural frames, sheathing,...
Lumber
Lumber is derived from logs which are harvested, debarked, and processed into long pieces with a rectangular cross-section. The transformation of logs into lumber involves multiple steps, beginning with an automated saw that slices the log into slabs. These slabs are then transported via a conveyor belt to smaller saws, where they are cut into square-edged pieces of specific widths.
Initially, the surfaces of these lumber pieces are rough, and their dimensions may vary slightly from one end to...
Initially, the surfaces of these lumber pieces are rough, and their dimensions may vary slightly from one end to...
Structural Properties and Dimensions of Lumber
Wood's structural properties derive from fibers aligned along the tree's length, contributing significantly to its mechanical strength. Wood exhibits up to twenty times greater tensile strength along these fibers compared to across them, and generally shows better performance under compression than tension. The length of fibers varies, with hardwoods having fibers around one twenty-fifth inch long and softwoods ranging from one-eighth to one-third inch.
The strength characteristics of wood are...
The strength characteristics of wood are...
Brick Cutting Techniques
Brick-cutting techniques involve various tools and methods to shape bricks for construction. A mason's hammer with a chisel-pointed end is used for basic shaping through sharp, precise strikes. For more complex shapes requiring higher precision, a power saw with a water-cooled diamond blade is used.
Cut bricks are categorized by size. Bricks cut to half their original length are called half-bats, while those cut to three-fourths their length are known as three-fourth bats.
Special types of cut...
Cut bricks are categorized by size. Bricks cut to half their original length are called half-bats, while those cut to three-fourths their length are known as three-fourth bats.
Special types of cut...
Survival Tree
Survival trees are a non-parametric method used in survival analysis to model the relationship between a set of covariates and the time until an event of interest occurs, often referred to as the "time-to-event" or "survival time." This method is particularly useful when dealing with censored data, where the event has not occurred for some individuals by the end of the study period, or when the exact time of the event is unknown.
Building a Survival Tree
Constructing a survival tree begins...
Building a Survival Tree
Constructing a survival tree begins...


