Molecular discovery seeks to generate chemical species tailored to very specific needs. In this paper, we present ORGANIC, a framework based on Objective-Reinforced Generative Adversarial Networks (ORGAN), capable of producing a distribution over molecular space that matches with a certain set of desirable metrics. This methodology combines two successful techniques from the machine learning community: a Generative Adversarial Network (GAN), to create non-repetitive sensible molecular species, and Reinforcement Learning (RL), to bias this generative distribution towards certain attributes. We explore several applications, from optimization of random physicochemical properties to candidates for drug discovery and organic photovoltaic material design.
Hossaini, Ryan, Chipperfield, Martyn P., Saiz-Lopez, Alfonso, Fernandez, Rafael, Monks, Sarah, Feng, Wuhu, Brauer, Peter, and von Glasow, Roland
CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET
Hydrogen chloride, chemistry.chemical_compound, chemistry, Anaerobic oxidation of methane, Sea salt, food.ingredient, food, Chemical transport model, Meteorology, Environmental chemistry, Methane, Aerosol, Chlorine, chemistry.chemical_element, Troposphere, TROPOSPHERIC CHLORINE, METHANE OXIDATION, VSL CHEMISTRY, Meteorología y Ciencias Atmosféricas, Ciencias de la Tierra y relacionadas con el Medio Ambiente, and CIENCIAS NATURALES Y EXACTAS
Chlorine atoms (Cl) are highly reactive toward hydrocarbons in the Earth's troposphere, including the greenhouse gas methane (CH). However, the regional and global CH sink from Cl is poorly quantified as tropospheric Cl concentrations ([Cl]) are uncertain by ~2 orders of magnitude. Here we describe the addition of a detailed tropospheric chlorine scheme to the TOMCAT chemical transport model. The model includes several sources of tropospheric inorganic chlorine (Cl), including (i) the oxidation of chlorocarbons of natural (CHCl, CHBrCl, CHBrCl, and CHBrCl) and anthropogenic (CHCl, CHCl, CCl, CHCl, and CHClCHCl) origin and (ii) sea-salt aerosol dechlorination. Simulations were performed to quantify tropospheric [Cl], with a focus on the marine boundary layer, and quantify the global significance of Cl atom CH oxidation. In agreement with observations, simulated surface levels of hydrogen chloride (HCl), the most abundant Cl reservoir, reach several parts per billion (ppb) over polluted coastal/continental regions, with sub-ppb levels typical in more remote regions. Modeled annual mean surface [Cl] exhibits large spatial variability with the largest levels, typically in the range of 1–5 × 10 atoms cm, in the polluted northern hemisphere. Chlorocarbon oxidation provides a tropospheric Cly source of up to ~4320 Gg Cl/yr, sustaining a background surface [Cl] of 20% of total boundary layer CH oxidation in some locations.
Organic Chemistry, High energy, Organic chemist, Intellectual development, Spin chemistry, Physical organic chemistry, History of science, Photochemistry, Chemistry, Supramolecular chemistry, and Electronic spin
This Perspective presents a review and survey of the science and philosophy of my research career over the past five decades at Columbia as a physical organic chemist and photochemist. I explore the role of paradigms, structure, and geometric thinking in my own cognitive and intellectual development. The Perspective describes my investigations of high energy content molecules in electronically excited states and the development of electronic spin and supramolecular photochemistry chemistry. Current research dealing with the nuclear spin chemistry of H2 incarcerated in buckyballs is illustrated. In the second part of this Perspective, I recount a personal role of the philosophy and history of science and the scientific communities’ use of paradigms in their every day research and intellectual activities. Examples are given of the crucial role of geometry and structure in the rapid development of organic chemistry and physical organic chemistry over the past century.
Deep Sea Research and Oceanographic Abstracts. 14:791-800
General Engineering, Nitrate, chemistry.chemical_compound, chemistry, Particulates, Phosphate, Total organic carbon, Dissolved organic carbon, Inorganic chemistry, Nitrogen cycle, Phosphorus, chemistry.chemical_element, Environmental chemistry, and Nitrogen
High concentrations in sea surface films of particulate and dissolved organic carbon, nitrogen and phosphorus, and of dissolved nitrate, ammonia and phosphate relative to their corresponding concentrations in subsurface waters are reported for stations off Peru and California. Ratios between organic carbon, nitrogen and phosphorus are utilized to interpret possible inter-relationships between particulate and dissolved organic matter. The effect of high surface film concentrations of organic and inorganic nitrogen is discussed with respect to the nitrogen cycle in the oceans.
Gregoire Danger, D Hendecourt, Louis Le Sergeant, Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
L'Actualité Chimique L'Actualité Chimique, Société chimique de France, 2012, pp.31--35 Publons HAL Gregoire Danger ResearcherID
[CHIM]Chemical Sciences, Astrophysics::Earth and Planetary Astrophysics, and Astrophysics::Galaxy Astrophysics
WOS:000305043300007; International audience; From interstellar chemistry to prebiotic chemistry: organic matter evolution toward the life The formation and evolution of organic matter starts mostly in dense molecular clouds. These clouds are mainly composed of interstellar grains, including most of the organic matter of 1:he interstellar medium embedded in molecular ices. During the evolution of these grains, this organic matter will undergo many chemical changes (ion bombardment, UV irradiations, and thermal effects) to achieve a true complexity of the organic matrix. In some areas, the cloud will collapse gravitationally on itself to form a "solar nebula" that will evolve into a protostar and potentially to a planetary system like our own. During this evolution, the interstellar grains will agglomerate to form small objects including the original organic matter, which from their evolution around the star can be described as comets or asteroids. These small objects can serve as a reservoir of organic matter for the development of prebiotic chemistry on the surface of terrestrial planets like the Earth, a prelude to the emergence of biosystems as it has indeed been the case on the Earth.
CHIMIA International Journal for Chemistry. 57:8-12
General Medicine, General Chemistry, Chemical polarity, Trace analysis, Focal point, High-performance liquid chromatography, Gas chromatography, Chromatography, Process engineering, business.industry, business, Chemistry, and Electrochromatography
The session 'Organic Trace Analysis - Challenges - Unsolved Problems' tried to give a 'state-of-the-art' view of some of the fundamental problems in organic trace analysis: How to resolve very complex mixtures into single compounds and to deal with the resulting flood of information. How to improve resolution of a demanding separation and to speed up analysis time. How to extract efficiently volatile polar compounds from water; a hardly solvable problem. In the following, leading experts in these fields give a synopsis progress report and outlook about some pieces of the complex puzzle of possible solutions, namely the role and status of separation columns in high performance liquid chromatography, the possibilities and limitations of electrochromatography, the on-line combination of sample preconcentration/clean-up with separation techniques, the modular on-line coupling of two GC columns and the enrichment of polar compounds in water by a LiCl-precolumn and high-resolution gas chromatography.
V.N. Varma, P. Nagabhushanam, B.S. Sukhija, and Dontireddy Venkat Reddy
Journal of Hydrology. 174:173-201
Water Science and Technology, Seawater, Geology, Alluvial aquifer, Hydrology, Seawater intrusion, Geochemistry, Aquifer, geography.geographical_feature_category, geography, Radiocarbon dating, law.invention, and law
Hydrosalinity evolution is examined in the Karaikal and Tanjavur coastal aquifers situated about 300 km south of Madras, Tamil Nadu, India. Ancient and modern sources of solutes in groundwaters have been differentiated using hydro-geochemical data, environmental radioisotope dates and organic biomarkers. Results from different techniques show consistently that the Pliocene aquifer possesses characteristic palmitoleic and oleic acid biomarkers, apparent 14 C ages of more than 20 000 years and high I/Cl ratio; the modern marine-estuarine intruded groundwaters in the alluvial aquifer display relatively younger apparent 14 C ages (modern to 3000 years), enriched potassium ion, low I/Cl ratio and contain vaccenic and hopanoic acid biomarkers, and they also tend to display transient changes in chemical characteristics. These results have practical importance with regard to identifying and controlling seawater intrusion in coastal areas.
Therrien, Eric, Englebienne, Pablo, Arrowsmith, Andrew G., Mendoza-Sanchez, Rodrigo, Corbeil, Christopher R., Weill, Nathanael, Campagna-Slater, Valérie, and Moitessier, Nicolas
Library and Information Sciences, Computer Science Applications, General Chemical Engineering, General Chemistry, Computational chemistry, Combinatorial Chemistry Techniques, Combinatorial chemistry, Medicinal chemistry, and Drug discovery
As part of a large medicinal chemistry program, we wish to develop novel selective estrogen receptor modulators (SERMs) as potential breast cancer treatments using a combination of experimental and computational approaches. However, one of the remaining difficulties nowadays is to fully integrate computational (i.e., virtual, theoretical) and medicinal (i.e., experimental, intuitive) chemistry to take advantage of the full potential of both. For this purpose, we have developed a Web-based platform, Forecaster, and a number of programs (e.g., Prepare, React, Select) with the aim of combining computational chemistry and medicinal chemistry expertise to facilitate drug discovery and development and more specifically to integrate synthesis into computer-aided drug design. In our quest for potent SERMs, this platform was used to build virtual combinatorial libraries, filter and extract a highly diverse library from the NCI database, and dock them to the estrogen receptor (ER), with all of these steps being ful...