scholarly journals Photoinduced C–H bond fission in prototypical organic molecules and radicals

2019 ◽  
Vol 21 (26) ◽  
pp. 13880-13901 ◽  
Author(s):  
Michael N. R. Ashfold ◽  
Rebecca A. Ingle ◽  
Tolga N. V. Karsili ◽  
Jingsong Zhang
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Primary Photochemistry ◽  
Hydrocarbon Molecules

We survey and assess current knowledge regarding the primary photochemistry of hydrocarbon molecules and radicals.

SCREENING EFFECTS AT ORGANIC–2D MATERIAL HETEROINTERFACES

2021 ◽  
pp. 2140008
Author(s):  
YU JIE ZHENG ◽  
ARRAMEL
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Raw Materials ◽  
2D Materials ◽  
Absorption Efficiency ◽  
Material Interfaces ◽  
Material Interface ◽  
Screening Effect ◽  
2D Material ◽  
Dielectric Screening

Organic molecule–two-dimensional material (OM–2D material) heterostructures are relatively an emergent class of hybrid-based electronic devices and yet have gained enormous interests. These systems hold promise towards application in the realization of electronic, optoelectronic and energy conversion devices, due to their tunable thickness, rich raw materials, flexibility, and also their capability to merge the high light absorption efficiency of organic molecules and the high carrier mobility of 2D materials. Dielectric screening effects have a large influence on electronic structure and optical properties at the OM–2D material interface due to the low intrinsic dielectric polarizability of both organic molecules and 2D materials. Here, we will review current knowledge about the dielectric screening behaviors in 2D materials and the screening effect at the OM–2D material heterointerfaces, including the physical origin of the dielectric screening effect across such interfaces, how to investigate it, and the influence of the screening effect on OM–2D material interfaces. Engineering of the dielectric screening effects in OM–2D material systems is also discussed. We conclude the review by illustrating a brief introduction of other important factors, e.g. defects, charge transfer, and hybridization, that will contribute to the screening effect and these features should be considered for the future scientific and device development of OM–2D material heterostructures.

Mechanism of primary photochemistry reactions in organic molecules using quantum chemistry methods

1998 ◽  
Author(s):  
Georgy V. Mayer ◽  
O. K. Bazyl ◽  
Victor Y. Artyukhov
Keyword(s):  
Quantum Chemistry ◽  
Organic Molecules ◽  
Primary Photochemistry

scholarly journals Organic Molecules in the Icy Bodies of Planetary Systems – Accepted Notions and New Ideas

2018 ◽  
Vol 27 (1) ◽  
pp. 341-355 ◽  
Author(s):  
Irakli Simonia ◽  
Dale P. Cruikshank
Keyword(s):  
Organic Molecules ◽  
Emission Lines ◽  
Photoluminescence Spectra ◽  
Spectral Emission ◽  
Small Bodies ◽  
Self Organized ◽  
New Ideas ◽  
Hydrocarbon Molecules ◽  
Complex Organic ◽  
Frozen Hydrocarbon Particles

Abstract Cometary bodies are acknowledged to contain some of the most pristine matter in the Solar System, including ices and minerals. Certain number of previously unidentified spectral emission features detected in comets can be explained as emission by hydrocarbon molecules enclosed in a Shpolskii matrix and forming frozen hydrocarbon particles. UV-induced photoluminescence spectra of several self-organized molecules exhibit emission lines coincident with unidentified cometary lines, and open the possibility of the presence of this complex organic as components of the pristine organic inventory of comets. Complex organic was detected also in three satellites of Saturn. We describe in this paper results of our investigation of complex organic of the small bodies and present new approaches and hypotheses.

Mineral skeletogenesis in sponges

2006 ◽  
Vol 84 (2) ◽  
pp. 322-356 ◽  
Author(s):  
María-J. Uriz
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Axial Filament ◽  
Environment Variables ◽  
Siliceous Sponges ◽  
Predominant Process ◽  
Points Of View ◽  
Siliceous Spicules ◽  
Genetically Determined ◽  
Axes Of Symmetry

Sponges secrete a variety of mineral skeletons consisting of calcite, aragonite, and (or) amorphous silica that confer strength and protect them from physical perturbations. Calcification takes place in a solution of bicarbonate and calcium ions, which is supersaturated with respect to both calcite and aragonite. In contrast, siliceous spicules are formed from an environment that is undersaturated with respect to silicon. Silification is the predominant process of biomineralization in extant sponges (92% of the species). The number of axes of symmetry in the large skeletal elements (megasclere spicules) is the main skeletal difference between the classes Hexactinellida (monaxons and triaxons) and Demospongiae (monaxons and tetraxons). Hypersilification occurs in both lithistid demosponges and hexactinellids, which are mostly confined to silicon-rich environments. Both siliceous and calcareous sponge skeletons are deposited within a well-defined restricted space by the so-called matrix-mediated mineralization. Both processes require organic molecules, which are secreted by a particular cell type (sclerocytes) and guide spicule formation. In most siliceous sponges, these molecules form a discrete filament, which is mainly triangular or quadrangular in cross section in demosponges and hexactinellids, respectively. No discrete axial filament has been reported for calcareous sponges. Silica polycondensation produces nanospheres to microspheres, which are arranged in concentric layers to form the spicules. The potential number of siliceous spicule types in a sponge species appears to be fixed genetically, but the environmental conditions (specifically the availability of silicon) may determine whether a genetically determined spicule type is finally expressed. In this study I review the current knowledge on sponge skeletogenesis, from molecular, cellular, and structural points of view. The contribution of environment variables, as well as the proliferation and decay of the main skeleton types in the past, are also considered.

scholarly journals Methods of plant root exudates analysis: a review

2011 ◽  
Vol 59 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Peter Dundek ◽  
Ladislav Holík ◽  
Tomáš Rohlík ◽  
Ladislav Hromádko ◽  
Valerie Vranová ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Root Exudates ◽  
Organic Molecules ◽  
Current Knowledge ◽  
Plant Root ◽  
Water Soluble ◽  
Low Molecular Weight ◽  
Total Carbohydrates ◽  
Electrophoresis Of Proteins

The aim of this review is to summarise current knowledge on methods being used to determine individual compounds and properties of water-soluble plant root exudates. These compounds include amino acids, organic acids and simple sugars, as well as polysaccharides, proteins and organic substances. Qualitative composition of water-soluble root exudates and exudation rate are commonly measured with the aim of consequent synthetic preparation of plant root exudates to be supplied to soil to create artificial rhizosphere for different experimental purposes. Root exudates collection usually requires consequent filtration or centrifugation to remove solids, root detritus and microbial cell debris, and consequent concentration using an evaporator, lyophilizator or ultrafiltration. Methods used for analysis of total groups of compounds (total proteins and total carbohydrates) and total organic carbon are simple. On the other hand, HPLC or GS/MS are commonly used to analyse individual low molecular weight organic molecules (sugars, organic acids and amino acids) with separation using different columns. Other properties such as pH, conductivity or activity of different enzymes as well as gel electrophoresis of proteins are sometimes assessed. All of these methods are discussed in this work.

scholarly journals Canine olfactory detection and its relevance to medical detection

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Paula Jendrny ◽  
Friederike Twele ◽  
Sebastian Meller ◽  
Albertus Dominicus Marcellinus Eras Osterhaus ◽  
Esther Schalke ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Potential Role ◽  
Organic Molecules ◽  
Current Knowledge ◽  
Wide Range ◽  
Volatile Organic ◽  
Olfactory Sense ◽  
Scent Detection ◽  
Olfactory Detection

AbstractThe extraordinary olfactory sense of canines combined with the possibility to learn by operant conditioning enables dogs for their use in medical detection in a wide range of applications. Research on the ability of medical detection dogs for the identification of individuals with infectious or non-infectious diseases has been promising, but compared to the well-established and–accepted use of sniffer dogs by the police, army and customs for substances such as money, explosives or drugs, the deployment of medical detection dogs is still in its infancy. There are several factors to be considered for standardisation prior to deployment of canine scent detection dogs. Individual odours in disease consist of different volatile organic molecules that differ in magnitude, volatility and concentration. Olfaction can be influenced by various parameters like genetics, environmental conditions, age, hydration, nutrition, microbiome, conditioning, training, management factors, diseases and pharmaceuticals. This review discusses current knowledge on the function and importance of canines’ olfaction and evaluates its limitations and the potential role of the dog as a biomedical detector for infectious and non-infectious diseases.

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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