Spin Transport in Single Layer Germanene: The Role of Electron Electron Scattering

Iridescent coloration plays an important role in the visual communication system of many animal taxa. It is known that iridescent structural colours result from layers of materials with different refractive indexes, which in feathers usually are keratin, melanin and air. However, the role of these materials in the production of structural iridescent coloration is still poorly documented. Despite the great interspecific variation in the organization of such structures in bird plumage, melanin layers are usually considered too opaque, suggesting its main role is to delineate the outermost keratin layer and absorb incoherently scattered stray light. We combined spectrometry, electron microscopy and thin-film optical modelling to describe the UV-reflecting iridescent colour of feather barbules of male blue-black grassquits ( Volatinia jacarina ), characterized by a keratin layer overlying a single melanin layer. Our models indicate that both the keratin and the melanin layers are essential for production of the observed colour, influencing the coherent scattering of light. The melanin layer in some barbules may be thin enough to allow interaction with the underlying keratin; however, individuals usually have, on an average, the minimum number of granules that optimizes absorbance by this layer. Also, we show that altering optical properties of the materials resulted in better-fitting models relative to the empirically measured spectra. These results add to previous findings concerning the influence of melanin in single-layer iridescence, and stress the importance of considering natural variation when characterizing such photonic structures.

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Here, there and everywhere – the importance of neutral lipids in plant growth and development

Postępy Biochemii ◽

10.18388/pb.2021_409 ◽

2021 ◽

Author(s):

Agnieszka Zienkiewicz ◽

Marta Saldat ◽

Krzysztof Zienkiewicz

Keyword(s):

Life Cycle ◽

Neutral Lipids ◽

Single Layer ◽

Pollen Grains ◽

Dynamic Nature ◽

Plant Life ◽

Plant Environment ◽

Plant Life Cycle ◽

Diverse Plant

In plants, lipids serve as one of the major and vital cellular constituents. Neutral lipids reserves play an essential role in the plant life cycle by providing carbon and energy equivalents for periods of active metabolism. The most common form of lipid storage are triacylglycerols (TAGs) packed into specialized organelles called lipid droplets (LDs). They have been observed in diverse plant organs and tissues, like oil seeds or pollen grains. LDs consist of a core, composed mostly of TAGs, enclosed by a single layer of phospholipids that is decorated by a unique set of structural proteins. Moreover, the recent advances in exploration of LDs proteome revealed a plethora of diverse proteins interacting with LDs. This is likely the result of a highly dynamic nature of these organelles and their involvement in many diverse aspect of cellular metabolism, tightly synchronized with plant developmental programs and directly related to plant-environment interactions. In this review we summarize and discuss the current progress in understanding the role of LDs and their cargo during plants life cycle, with a special emphasis on developmental aspects.

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The Structure of the Macromolecular Units on the Cell Walls of Bacillus Polymyxa

Journal of Cell Science ◽

10.1242/jcs.2.4.587 ◽

1967 ◽

Vol 2 (4) ◽

pp. 587-591

Author(s):

J. T. FINCH ◽

A. KLUG ◽

M.V. NERMUT

Keyword(s):

Cell Wall ◽

Electron Micrographs ◽

Electron Scattering ◽

Cell Walls ◽

Single Layer ◽

Optical Diffraction ◽

Square Lattice ◽

Bacillus Polymyxa ◽

Optical Filtering ◽

Diffraction Patterns

Electron micrographs of negatively stained preparations of cell walls of Bacillus polymyxa have been investigated by optical diffraction and optical filtering techniques. Images of single layers of the cell wall, from which the ‘noise’ has been filtered optically, show hollow, square-shaped morphological units arranged on a square lattice of side 100 Å. Single-layer images showing the same pattern have been filtered from moiré patterns arising from two overlapping single layers. The morphological units are composed of four smaller subunits. The optical diffraction patterns from regions of two overlapping layers show extra reflexions which are attributed to multiple electron scattering.

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Abstract 192: A Hypothesis on Initiation of Coronary Atherosclerosis: The Role of Intimal Neovascularization and Proliferation. Do Lipoproteins Invade Coronary Tunica Intima from the Opposite Site?

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.32.suppl_1.a192 ◽

2012 ◽

Vol 32 (suppl_1) ◽

Author(s):

Vladimir M Subbotin

Keyword(s):

Coronary Atherosclerosis ◽

Binding Capacity ◽

Good Reason ◽

Single Layer ◽

Vasa Vasorum ◽

Great Expectations ◽

Diffuse Intimal Thickening ◽

Arterial Intima ◽

Capillary Bed

Objectives Tremendous success of statins in coronary atherosclerosis (CA) prevention offered great expectations for extended protection and effective therapeutics. However, stalled progress in pharmaceutical treatment gives a good reason to review whether the hypothesis underlining our efforts is consistent with undoubted facts on coronary artery in normal and diseased forms. Analysis An accepted hypothesis states that CA is initiated by endothelial dysfunction due to inflammation and high levels of LDL, followed by lipids and macrophage penetration into arterial intima and plaque formation. It is crucial to highlight that normal coronary intima is not a single-layer endothelium covering thin acellular compartment, as is commonly claimed in most publications, but always appears as a multi-layer cellular compartment, or diffuse intimal thickening (DIT), where cells are arranged in a few dozens layers. Since it is unanimously agreed that LDL invade DIT from lumen, the initial depositions ought to be most proximal to blood, i.e. in inner DIT layers. The facts show that the opposite is true, and lipids are deposited in the outer DIT. This contradiction is resolved by noting that normal DIT is always avascular, receiving oxygen and nutrients by diffusion from lumen, whereas in CA outer DIT is always neovascularized from adventitial vasa vasorum . Proteoglycan biglycan, confined to outer DIT of normal and diseased coronary, has high binding capacity for LDL. However, normal DIT is avascular, whereas in CA biglycan of outer DIT layers appears in direct contact with blood and extract lipoproteins. These facts explain patterns and mechanisms of CA initiation, which is not unique: normally avascular cornea accumulates lipoproteins after neovascularization, resulting in lipid keratopathy. The author offers a hypothesis on neovascularization. Cells in coronary DIT possess high proliferative capacity. Excessive cell replication increases DIT thickness, impairs diffusion, resulting in hypoxia of outer DIT. Hypoxia induces neovascularization of outer DIT layers, where biglycan extracts LDL from newly formed capillary bed, initiating CA. Conclusion Controls of cell proliferation and neovascularization in coronary DIT should be a priority of our research.

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Role of methylation in electron scattering on X(CH3)4 (X= C, Si, Ge) molecules

Journal of Physics Conference Series ◽

10.1088/1742-6596/1412/5/052008 ◽

2020 ◽

Vol 1412 ◽

pp. 052008

Author(s):

Sylwia Stefanowska-Tur ◽

Czesław Szmytkowski ◽

Elżbieta Ptasińska-Denga ◽

Paweł Możejko

Keyword(s):

Electron Scattering

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Gravity Wave Emission by Shear Instability

Journal of Physical Oceanography ◽

10.1175/jpo-d-19-0029.1 ◽

2019 ◽

Vol 49 (9) ◽

pp. 2393-2406 ◽

Cited By ~ 1

Author(s):

Carsten Eden ◽

Manita Chouksey ◽

Dirk Olbers

Keyword(s):

Gravity Wave ◽

Single Layer ◽

Internal Gravity Waves ◽

Shear Instability ◽

Vertical Shear ◽

Wave Signal ◽

Wave Emission ◽

Balanced Flow ◽

Single Layer Model

AbstractGravity wave emission by geostrophically balanced flow is diagnosed in numerical simulations of lateral and vertical shear instabilities. The diagnostic method in use allows for a separation of balanced flow and residual wave signal up to fourth order in the Rossby number (Ro). While evidence is found for a small but finite gravity wave emission from balanced flow in a single-layer model with large lateral shear and large Ro, a vertically resolved model with moderate velocity amplitudes appropriate to the interior ocean hardly shows any wave emission. Only when static instabilities generated by the shear instability of the balanced flow are allowed can a gravity wave signal similar to the ones reported in earlier studies be detected in the vertically resolved case. This result suggests a relatively small role of spontaneous wave emission in the classical sense of Lighthill radiation, and emphasizes the role of convective or symmetric instabilities during frontogenesis for the generation of internal gravity waves in the ocean and atmosphere.

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