morphological characteristics

形态特征
  • 文章类型: Journal Article
    花苞片(小片,caterphills)是叶状器官,对着花或花序,但具有非花起源;它们存在于多种物种中,代表多个独立的起源,在形式和功能上表现出很大的变化。尽管在过去的150年中,人们一直在关注苞片,我们对它们的适应性意义的理解仍然非常不完整。这是因为大多数对苞片功能和进化的研究仅集中在一种或几种选择性因素上。人们普遍认为,苞片经历传粉媒介的选择,特别是通过强烈的视觉增强传粉者的吸引力,嗅觉,或与背景的回声声学对比,并通过传粉者奖励的存在发出信号,要么诚实地(为传粉者提供奖励),或欺骗性的(没有奖励甚至诱捕传粉者的吸引力)。然而,近几十年的研究表明,片的进化也受到传粉者以外的因子的影响。苞片可以保护花朵,水果,或通过显示警告信号来自食草动物的种子,伪装显眼的生殖器官,或通过提供物理屏障或有毒化学物质。对已发表研究的评论表明,苞片还可以促进种子传播并改善非生物应激源的影响,如低温,强烈的紫外线辐射,大雨,干旱,和/或机械磨损,对生殖器官或植物传粉者。此外,授粉后的绿色苞片和五颜六色的苞片的绿化促进了光合活性,为果实或种子发育提供大量碳(光合产物),尤其是在植物生命周期或季节的晚期,当树叶开始衰老的时候。另一层复杂性源于这样一个事实,即驱动苞片进化的选择因子在物种之间甚至在物种内的不同发育阶段之间变化,一种药剂的选择可以被其他药剂加强或反对。总之,我们对文献的调查表明,苞片是多功能的,并且受到多种选择剂的影响。为了充分理解苞片的功能和进化意义,有必要在植物的整个生命周期中考虑多种选择剂,使用综合方法进行数据收集和分析。
    Floral bracts (bracteoles, cataphylls) are leaf-like organs that subtend flowers or inflorescences but are of non-floral origin; they occur in a wide diversity of species, representing multiple independent origins, and exhibit great variation in form and function. Although much attention has been paid to bracts over the past 150 years, our understanding of their adaptive significance remains remarkably incomplete. This is because most studies of bract function and evolution focus on only one or a few selective factors. It is widely recognised that bracts experience selection mediated by pollinators, particularly for enhancing pollinator attraction through strong visual, olfactory, or echo-acoustic contrast with the background and through signalling the presence of pollinator rewards, either honestly (providing rewards for pollinators), or deceptively (attraction without reward or even trapping pollinators). However, studies in recent decades have demonstrated that bract evolution is also affected by agents other than pollinators. Bracts can protect flowers, fruits, or seeds from herbivores by displaying warning signals, camouflaging conspicuous reproductive organs, or by providing physical barriers or toxic chemicals. Reviews of published studies show that bracts can also promote seed dispersal and ameliorate the effects of abiotic stressors, such as low temperature, strong ultraviolet radiation, heavy rain, drought, and/or mechanical abrasion, on reproductive organs or for the plants\' pollinators. In addition, green bracts and greening of colourful bracts after pollination promote photosynthetic activity, providing substantial carbon (photosynthates) for fruit or seed development, especially late in a plant\'s life cycle or season, when leaves have started to senesce. A further layer of complexity derives from the fact that the agents of selection driving the evolution of bracts vary between species and even between different developmental stages within a species, and selection by one agent can be reinforced or opposed by other agents. In summary, our survey of the literature reveals that bracts are multifunctional and subject to multiple agents of selection. To understand fully the functional and evolutionary significance of bracts, it is necessary to consider multiple selection agents throughout the life of the plant, using integrative approaches to data collection and analysis.
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  • 文章类型: Journal Article
    碳材料技术提供了低成本合成的可能性,出色的性能替代贵金属催化剂长期使用。石墨烯(GDY)是具有极薄原子厚度的碳同素异形体。它由碳元素组成,与两个sp杂交。和sp2,导致多层二维(2D)配置。几个功能模型表明,GDY包含自发存在的带狄拉克极点的带结构。这是由于碳原子之间的不均匀相互作用,这是2pz子壳的各种融合和重叠的结果。与其他碳同素异形体不同,GDY有狄拉克锥安排,这反过来又赋予了它独特的理化特性。这些特性包括可调节的固有能隙,高速充电传输调制效率,和特殊的电导。许多科学家对这样的小说感兴趣,线性,堆叠材料,包括GDY。因此,一直在进行有组织的GDY合成,使其成为最早合成的GDY材料之一。有几种方法可以操纵GDY的能带结构,包括施加应力,引入硼/氮负载,利用纳米线,和氢化。GDY的柔性可以通过纳米壁的形成得到有效的证明,纳米结构,纳米管图案,纳米棒,或结构化的条带簇。GDY,作为一种碳材料,具有广泛的应用由于其显著的结构和电气特性。根据随后的研究,GDY可用于许多能源生产过程,如电化学水分解(ECWS),光电化学水分解(PECWS),氮还原反应(NRR),整体水分解(OWS),氧还原反应(ORR),储能材料,锂离子电池(LiBs)和太阳能电池的应用。这些研究表明,GDY的使用对开发和实施有效的,多模态,和具有现实应用的智能催化剂。然而,GDY和基于GDY的复合材料在即将进行的研究中的局限性同样得到承认。这些研究的目的是提供有关GDY的全面知识,并激发这些独特碳材料的进一步发展和利用。
    Carbon materials technology provides the possibility of synthesizing low-cost, outstanding performance replacements to noble-metal catalysts for long-term use. Graphdiyne (GDY) is a carbon allotrope with an extremely thin atomic thickness. It consists of carbon elements, that are hybridized with both sp. and sp2, resulting in a multilayered two-dimensional (2D) configuration. Several functional models suggest, that GDY contains spontaneously existing band structure with Dirac poles. This is due to the non-uniform interaction among carbon atoms, which results from various fusions and overlapping of the 2pz subshell. Unlike other carbon allotropes, GDY has Dirac cone arrangements, that in turn give it inimitable physiochemical characteristics. These properties include an adjustable intrinsic energy gap, high speeds charging transport modulation efficiency, and exceptional conductance. Many scientists are interested in such novel, linear, stacked materials, including GDY. As a result, organized synthesis of GDY has been pursued, making it one of the first synthesized GDY materials. There are several methods to manipulate the band structure of GDY, including applying stresses, introducing boron/nitrogen loading, utilizing nanowires, and hydrogenations. The flexibility of GDY can be effectively demonstrated through the formation of nano walls, nanostructures, nanotube patterns, nanorods, or structured striped clusters. GDY, being a carbon material, has a wide range of applications owing to its remarkable structural and electrical characteristics. According to subsequent research, the GDY can be utilized in numerous energy generation processes, such as electrochemical water splitting (ECWS), photoelectrochemical water splitting (PEC WS), nitrogen reduction reaction (NRR), overall water splitting (OWS), oxygen reduction reaction (ORR), energy storage materials, lithium-Ion batteries (LiBs) and solar cell applications. These studies suggested that the use of GDY holds significant potential for the development and implementation of efficient, multimodal, and intelligent catalysts with realistic applications. However, the limitation of GDY and GDY-based composites for forthcoming studies are similarly acknowledged. The objective of these studies is to deliver a comprehensive knowledge of GDY and inspire further advancement and utilization of these unique carbon materials.
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