scholarly journals The Diffuse Interstellar Bands: an Elderly Astro-Puzzle Rejuvenated

2011 ◽  
Vol 7 (S280) ◽  
pp. 162-176 ◽  
Author(s):  
Nick L. J. Cox
Keyword(s):  
Interstellar Medium ◽  
Organic Compounds ◽  
Recent Progress ◽  
Organic Molecules ◽  
Exact Nature ◽  
Diffuse Band ◽  
Small Organic Molecules ◽  
Complex Component ◽  
Diffuse Interstellar Bands ◽  
The Universe

AbstractThe interstellar medium constitutes a physically and chemically complex component of galaxies and is important in the cycle of matter and the evolution of stars. From various spectroscopic clues we now know that the interstellar medium is rich in organic compounds. However, identifying the exact nature of all these components remains a challenge. In particular the identification of the so-called diffuse band carriers has been alluding astronomers for almost a century.In recent decades, observational, experimental and theoretical advances have rapidly lead to renewed interest in the diffuse interstellar bands (DIBs). This has been instigated partly by their perceived relation to the infrared aromatic emission bands, the UV extinction bump and far-UV rise, and the growing number of (small) organic molecules identified in space.This chapter gives an overview of the observational properties and behaviour of the DIBs, and their presence throughout the Universe. I will highlight recent progress in identifying their carriers and discuss their potential as tracers and probes of (extra)-Galactic ISM conditions.

Thermal and photochemical study of CH3OH and CH3OH–O2 astrophysical ices

2020 ◽  
Vol 500 (1) ◽  
pp. 1188-1200
Author(s):  
Killian Leroux ◽  
Lahouari Krim
Keyword(s):  
Interstellar Medium ◽  
Organic Compounds ◽  
Organic Molecules ◽  
Uv Light ◽  
Hydrogen Abstraction ◽  
Insertion Reaction ◽  
Abstraction Reaction ◽  
Uv Photons ◽  
Astrophysical Ices ◽  
Complex Organic

ABSTRACT Methanol, which is one of the most abundant organic molecules in the interstellar medium, plays an important role in the complex grain surface chemistry that is believed to be a source of many organic compounds. Under energetic processing such as ultraviolet (UV) photons or cosmic rays, methanol may decompose into CH4, CO2, CO, HCO, H2CO, CH3O and CH2OH, which in turn lead to complex organic molecules such as CH3OCHO, CHOCH2OH and HOCH2CH2OH through radical recombination reactions. However, although molecular oxygen and its detection, abundance and role in the interstellar medium have been the subject of many debates, few experiments on the oxidation of organic compounds have been carried out under interstellar conditions. The present study shows the behaviour of solid methanol when treated by UV light and thermal processing in oxygen-rich environments. Methanol has been irradiated in the absence and presence of O2 at different concentrations in order to study how oxidized complex organic molecules may form and also to investigate the O-insertion reaction in the C–H bound to form methanediol HOCH2OH through a CH3OH + O(1D) solid-state reaction. The adding of O2 in the thermal and photochemical reaction of solid methanol leads to the formation of O3, H2O and HO2, in addition to three main organics, HCOOH, CHOCHO and HOCH2OH. We show that in an O2-rich environment, species such as CO, CH4, HCO, CH3OH and CHOCH2OH are oxidized into CO2, CH3OH, HC(O)OO, HOCH2OH and CHOCHO, respectively, while HCOOH might be formed through the H2CO + O(3P) → (OH + HCO)cage → HCOOH hydrogen-abstraction reaction.

scholarly journals Development of endogenous enzyme-responsive nanomaterials for theranostics

2018 ◽  
Vol 47 (15) ◽  
pp. 5554-5573 ◽  
Author(s):  
Jing Mu ◽  
Jing Lin ◽  
Peng Huang ◽  
Xiaoyuan Chen
Keyword(s):  
Hybrid Materials ◽  
Recent Progress ◽  
Organic Molecules ◽  
Building Blocks ◽  
Small Organic Molecules ◽  
Organic Hybrid

This review summarizes the recent progress of endogenous enzyme-responsive nanomaterials based on different building blocks such as polymers, liposomes, small organic molecules, or inorganic/organic hybrid materials for theranostics.

scholarly journals Diffuse Interstellar Bands in Emission

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
T. B. Williams ◽  
P. Sarre ◽  
C. C. M. Marshall ◽  
K. Spekkens ◽  
R. Kuzio de Naray
Keyword(s):  
Interstellar Medium ◽  
Radiation Field ◽  
Emission Feature ◽  
Large Telescope ◽  
Diffuse Band ◽  
Diffuse Interstellar Bands ◽  
Fabry Perot ◽  
The Galaxy

AbstractRecent Fabry-Pérot observations towards the galaxy NGC 1325 with the Southern African Large Telescope (SALT) led to the serendipitous discovery of an emission feature centered at 661.3 nm arising from material in the interstellar medium (ISM) of our Galaxy; this emission feature lies at the wavelength of one of the sharper and stronger diffuse bands normally seen in absorption. The flux of the feature is 4.2 ± 0.5 × 10−18 es−1 cm−2 arcsec−2. It appears that this is the first observation of emission from a diffuse band carrier in the ISM, excited in this case by the interstellar radiation field. We present the discovery spectra and describe follow-up measurements proposed for SALT.

scholarly journals Ferroelectric columnar assemblies from the bowl-to-bowl inversion of aromatic cores

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shunsuke Furukawa ◽  
Jianyun Wu ◽  
Masaya Koyama ◽  
Keisuke Hayashi ◽  
Norihisa Hoshino ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Organic Molecule ◽  
Remanent Polarization ◽  
Organic Molecules ◽  
Materials Science ◽  
State Of The Art ◽  
Condensed Matter ◽  
Small Organic Molecules ◽  
Organic Ferroelectrics ◽  
Potential Use

AbstractOrganic ferroelectrics, in which the constituent molecules retain remanent polarization, represent an important topic in condensed-matter science, and their attractive properties, which include lightness, flexibility, and non-toxicity, are of potential use in state-of-the-art ferroelectric devices. However, the mechanisms for the generation of ferroelectricity in such organic compounds remain limited to a few representative concepts, which has hitherto severely hampered progress in this area. Here, we demonstrate that a bowl-to-bowl inversion of a relatively small organic molecule with a bowl-shaped π-aromatic core generates ferroelectric dipole relaxation. The present results thus reveal an unprecedented concept to produce ferroelectricity in small organic molecules, which can be expected to strongly impact materials science.

scholarly journals Recent Progress in Fluorescent Probes for Zn2+/Cd2+Based on Small Organic Molecules

2012 ◽  
Vol 32 (10) ◽  
pp. 1803 ◽  
Author(s):  
Jia Jia ◽  
Xi Tang ◽  
Yingfang He ◽  
Mengyu Zhang ◽  
Guowen Xing
Keyword(s):  
Fluorescent Probes ◽  
Recent Progress ◽  
Organic Molecules ◽  
Small Organic Molecules

QUBEKit: Automating the Derivation of Force Field Parameters from Quantum Mechanics

2019 ◽  
Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole
Keyword(s):  
Quantum Mechanics ◽  
Force Field ◽  
Organic Molecules ◽  
Force Fields ◽  
Liquid Density ◽  
Small Organic Molecules ◽  
Automated Generation ◽  
Energy Of Hydration ◽  
Novel Method ◽  
Force Field Parameters

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>

QUBEKit: Automating the Derivation of Force Field Parameters from Quantum Mechanics

2019 ◽  
Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole
Keyword(s):  
Quantum Mechanics ◽  
Force Field ◽  
Organic Molecules ◽  
Force Fields ◽  
Liquid Density ◽  
Small Organic Molecules ◽  
Automated Generation ◽  
Energy Of Hydration ◽  
Novel Method ◽  
Force Field Parameters

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>

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