The basic tenet of the heterotrophic theory of the origin of life is that the maintenance and reproduction of the first living systems depended primarily on prebiotically synthesized organicmolecules. It is unlikely that any sin- gle mechanism can account for the wide range of organic compounds that may have accumulated on the primitive Earth, suggesting that the prebiotic soup was formed by contributions from endogenous syntheses in reducing envi- ronments, metal sulphide-mediated synthesis in deep-sea vents, and exogenous sources such as comets, meteorites and interplanetary dust. The wide range of experimental conditions under which amino acids and nucleobases can be synthesized suggests that the abiotic syntheses of these monomers did not take place under a narrow range de- fined by highly selective reaction conditions, but rather under a wide variety of settings. The robustness of this type of chemistry is supported by the occurrence of most of these biochemical compounds in the Murchison meteorite. These results lend strong credence to the hypothesis that the emergence of life was the outcome of a long, but not necessarily slow, evolutionary processes. The origin of life may be best understood in terms of the dynamics and evolution of sets of chemical replicating entities. Whether such entities were enclosed within membranes is not yet clear, but given the prebiotic availability of amphiphilic compounds this may have well been the case. This scheme is not at odds with the theoretical models of self-organized emerging systems, but what is known of biology suggest that the essential traits of living systems could have not emerged in the absence of genetic material able to store, express and, upon replication, transmit to its progeny information capable of undergoing evolutionary change. How such genetic polymer first evolved is a central issue in origin-of-life studies.
The adsorption of organic and biological molecules onto surfaces is a topic of increased interest in some scientific and technological fields, since the molecular interactions at the molecule/surface interface play an important role in the design of implants, sensors and immunoassays, and so forth. For example, with the adsorption of organicmolecules, material surfaces can be provided with unique characteristics of the organicmolecules, such as their absorption spectrum, chemical affinity and hydrophobicity/hydrophilicity. This process is known as organic functionalization, whose ultimate goal is the production of novel nano-electronic devices with properties such as light emission, light detection and chemical sensitivity. On the other hand, with the study of protein adsorption onto surfaces, the design of novel biocompatible materials and medical sensing devices becomes at hand. In this work, we study the adsorption of molecules, belonging to the groups of proteins and unsaturated hydrocarbons, onto material surfaces of laminar constitution, such as graphite, graphene, silicene and germanene. Recent achievements associated with graphene have led to the research of analogue two-dimensional structures, such as silicene and germanene. In general, these surfaces offer promising advances in the nano-electronics and biotechnology fields. In the analysis of the adsorption of biological molecules, we study the influence of topographic modifications on graphite for the adsorption of proteins, such as the albumin. For such a study, we use molecular simulations based on classical mechanics, such as molecular mechanics and molecular dynamics. The results show that topographic modifications on graphite do not influence protein unfolding. This suggests a favorable degree of biocompatibility for graphite to be used for the adsorption of biological molecules. In the analysis of the adsorption of organicmolecules, we study the adsorption of acetylene, ethylene and styrene on hydrogenated graphene, silicene and germanene surfaces, by means of a chain reaction activated by radicals. The study of breaking and bond formation as well as the electronic structure at each of the reaction steps was addressed with molecular simulations based on quantum mechanics, such as the density functional theory. The results show that the organic functionalization is more favorable with silicene and germanene than with graphene.
Protein kinases were initially though to be unsuitable drug targets, largely because the unfavourably high degree of structural conservation within the catalytic domains of all protein kinases, particularly the ATP binding site. However, the degree of conservation of the ATP binding sites in the distinct protein kinases is not absolute, so it is possible to developed ATP mimicry with relatively high selectivity. Currently, the development of ATP mimics has been the most extensive exploited strategy for kinase inhibition, and most of protein kinase inhibitors currently approved by the Food and Drug Administration (FDA) or in different stages of clinical trials for cancer therapy, are directed toward the ATP binding pocket [27-29]. About four inhibition mechanisms of protein kinase activity using small organicmolecules (a, b, c) or antibodies (d) have been developed: (a) an ATP-mimetic mechanism, (b) a substrate mimetic mechanism, (c) a mechanism locking the kinase into inactive conforma- tion and (d) the recognition of ligand binding site in the receptor tyrosine kinase preventing receptor’s activation [27, 30-32].
In recent years, interest in the presence of organic and biological molecules in space has grown considerably due to the increasing number of discoveries by modern radio telescopes and also by analyses of the compositions of meteorites and comets. If one is interested in molecules in the interstellar medium ( ISM ) , the list of organic and biological molecules detected is continually becoming larger. In addition to the well-known disputed case of the simplest amino acid, glycine ( Kuan et al. 2003; Snyder et al. 2005; Cunningham et al. 2007; Jones et al. 2007 ) , there have also been detections of molecules with ( NH – C = O ) peptide bond, like formamide ( Rubin et al. 1971 ) , acetamide ( Hollis et al. 2006 ) , and of other biologically relevant organicmolecules like glycolaldehyde ( the ﬁ rst sugar; Hollis et al. 2000 ) , urea ( Remijan et al. 2014 ) , methyl acetate ( Tercero et al. 2013 ) , acetaldehyde ( Gottlieb et al. 1973; Fourikis et al. 1974; Gilmore et al. 1976 ) , and amino acetonitrile ( Belloche et al. 2008 ) .
One of the most relevant traits of the density functional language is its suitability for defining and elucidating important chemical concepts of molecular structure and reactivity. Parallel to the development of quantum-chemical models to approach the Hohenberg-Kohn equation , Parr developed the so-called “conceptual DFT” in the late 1970s and early 1980s . Conceptual DFT is a DFT-subfield in which one tries to extract from the electron density relevant concepts and principles that make it possible to understand and predict the chemical behaviour of a molecule. Parr and co-workers, and later a large community of theoretical chemists, have been able to give precise definitions for chemical concepts which had already been known and used for many years in various branches of chemistry, electronegativity as the most noticeable example, thus providing their calculations with a quantitative use. Herein, the most relevant indices defined within the conceptual DFT  for the study of the organic reactivity are discussed.
thousands of spectral features are still observed in the line surveys captured by numerous observational facilities working on the ground (e.g. IRAM, ALMA, GBT, NRAO, BIMA, CARMA, CSO, SEST) or in space (Hershel/HIFI). The new generation of telescopes, especially such as the ALMA project, is bringing scientifically very important data, since the sensitivity and angular resolution are substantially improved in comparison with other currently used single-dish telescopes. These capabilities open more possibilities toward detections of interstellar molecules in smaller abundances than before. The frequency coverage of the ALMA interferometer from 84 to 720 GHz thus motivates laboratory spectroscopists to record and analyze the rotational spectra in the millimeter and sub-millimeter wave region and to gather an atlas of line positions and intensities for potentially detectable molecules. Acrylic acid (prop-2- enoic acid, CH 2 =CH-COOH) is the simplest unsaturated carboxylic acid and seems to be a logical
When a molecule rotates, the centrifugal force pulls the atoms apart causing an increase in its moment of inertia and decreasing the rotational constant as- sociated to this energy term. This effect couples both types of interactions, vibration and rotation. In order to understand this interaction, the follow- ing analogy can be useful: a pair of masses (atoms of a diatomic molecule) are attached at the ends of a spring, so that the masses can vibrate along the line between them. The spring is fixed at some point to the center of a rotating disk. The system has no friction. Due to rotation, the Coriolis force de- flects the masses, changing the vibration frequency of the spring, reflecting an interaction between rota- tion and vibration in this mechanical system. This is analogous to the interaction between rotation and vibration in diatomic molecules.
The main objective of this bibliographic review was to investigate organochlorine pesticides degradation by application of TiO2 nanoparticles, in this study, organochlorine pesticides were identified as the main persistent pollutants in water bodies. In Ecuador 50.7% of permanent crops and 81.4% of transients crops use agrochemicals (includes organochlorine pesticides) which generate persistent residues stay in the environment for long periods of time. Advanced oxidation processes are found as workable techniques for degradation of organic and inorganic pollutants; in particular, raw water and wastewater treatment by heterogeneous photocatalysis with the use of titanium dioxide nanoparticles is a viable technique, due to its ability to mineralize organic pollutants, reduce heavy metals, and destroy microorganisms.
While total metal content of the sediments may not be indicative of their effects on the benthos the metal content of polychaetes has been utilized with variable results as an indica- tor of heavy metal burden of the sediments. Early work by Luoma & Bryan (1982) reported that N. (H.) diversicolor, Perinereis cultrifera (Family Nereididae) and Nephtys hombergi, exhibited Cu concentrations directly related those in the sediment. Later, however, Bryan & Gibbs (1987) found that the ampharetid Melinna palmata and the cirratulid Tharyx marioni seemed to be able to regulate, at least partially, their Cu content making these less likely to serve as indicators for this metal. H. filiformis and the nerid Perinereis albuhitensis were high in abundance at sites close to a sew- age outfall on the west coast of Korea and were indicators of pollution but they also contained high levels of Cu, Pb and Cd indicating heavy metal pollution as well as organic enrichment. Working at sites in France and the United Kingdom, Berthet et al. (2003) found that the bioaccumulation of Cd and Cu (but not Zn) increased with metal content of the sediments in N. (H.) diversicolor. Conversely, Poirier et al. (2006) found no correlation between metal concentrations (Ag, Cd, CU, Pb and Zn) in N. (H.) diversicolor and the sediments from which they were collected on the nearby French coast of the English Channel.
the fundamental principle of the technique, by taking advantage of the 5’ to 3’ exonuclease activity of Taq polymerase enzyme. In this work, researchers introduced onto the PCR reaction a non-extendable oligonucleotide probe in its 3’ end and labeled with a radioactive phosphorus molecule at the 5’ end. During amplification, the Taq polymerase exonuclease activity degrades the probe into small fragments, whose amount was measured via autoradiography and was directly proportional to the initial number of target molecules of the reaction. This technique is the basic principle used in real-time PCR especially that used in the detection system through TaqMan® probes, which will be discussed in detail further ahead.
The organic-rich unit (figure 2) is repre- sented by 110 cm of cored sediment, herein described as sapropel (figure 3). On the ba- sis of its TOC profile and organic facies (figure 4), it has been subdivided into lower and upper sapropels, respectively 76 and 34 cm thick. Dark grey to green in colour and rich in the small gastropod Coxiella sp. at its base, the lower sapropel grades upward into indistinctly laminated, dark green to black, rubbery mudstone with alternating dark and light bands 1−2 cm thick and sporadic lenses of the aforementioned gastropod, before re- verting to thin intervals reminiscent of the basal facies. The lower and upper margins of the lower sapropel are paler in colour and lack the lamination of its middle portion, reflecting their greater bioturbation and pel- letisation and consequent oxidation of their dispersed aquatic organic matter (table 2). Even today, Coxiella sp. becomes an active grazer around the shallow margins of the lake following its freshening by winter rain- fall (WARREN, 1988).
Organic production has been increasing significantly in recent years in Brazil, from 100 000 ha in 2000 to almost 900 000 ha in 2007 (De Abreu et al., 2008). Pineap- ples, bananas, coffee, honey, milk, meat, soybeans, palm hearts, sugar, chicken and green vegetables are the main products. About 90 percent of this production is now exported to the United States of America, the EU and Japan (especially bananas, soybeans and coffee). Brazil is also a significant exporter of organic orange juice and organic sugar. Supermarkets account for 45 percent of domestic organic sales and marketplaces and specialized stores represent 26 and 16 percent, respectively. The principal products sold in these outlets are fresh fruit and vegetables, although there is an increasing trend towards processed organic products (teas, vegetable oils, cereals and milk). This growth is not only associated with consumers’ needs, but is also part of the competitive strategy of the country’s retailers to offer organic products to their customers. The growth of organic production in Brazil may also be explained in terms of the development of several different institutional relation- ships as well as an implementation of governmental policies specifically designed to support and promote the sector.
tions like that in panel (d), with a C atom on top of the Au atom. This small barrier height is common to benzene and toluene, and indicates that at moderate temperatures, aromatic molecules will continuously revolve around their binding sites on the gold catalyst. If the aromatic molecule possesses addi- tional functional groups which can interact with gold, then it is likely that it will easily reorient itself in order to find the optimal adsorption conformation.
Sequential reactions (also known as "one-pot") are those that all reagents and substrates are placed into a flask to give the final product without further additions, isolates or manipulations (excepting of course the final isolation of the desired product) (Fraile et al., 2011). They are characterized by their elegance, high stereoselectivity and the simple way to perform them. Those reactions allow constructing complex molecules in a few synthetic steps and of- ten are characterized by a lack of collateral products, becoming as environmentally friendly alternatives. In addition, the amount of solvent required for one-pot process is comparatively much lower to that of multi- stage processes. This kind of reaction has extensively been studied in recent years and, due to its favorable qualities, most likely will be the "process key" of the organic chemistry (Marson, 2012).
The sustainability of continuous cropping systems depends heavily on the years of intensive agricultural production and the choice of crop sequence that alters the fractions of soil organic matter. The aim of this study was to evaluate the impact of continuous soybean cultivation on fractions of organic carbon in the vertic Argiudolls of the Argentinean Pampas. Total organic carbon (TOC), particulate organic carbon (POC ), fulvic acids (FA), humic acids (HA), humin (H) and carbon produced by microbial respiration (Cresp) were assessed in plots with continuous production of soybean for over 15 years (SP) and grassland plots that were considered the change control (GP). A significant reduction of TOC and POC variables in cultured soybean SP plots, relative to grassland GP, was observed. The POC / TOC and Cresp / TOC ratios were significantly lower in soybean plots than in grasslands used as controls. These ratios were interpreted as a preferential tendency to maintain high rates of mineralization of labile carbon forms and increased biological stability of humified forms in cultured soybean plots. The shapes of the humic fractions of less complexity, FA and HA, were significantly reduced in the latter plots compared with grasslands, while no significant changes occurred in the more stable and recalcitrant forms of carbon, such as humin, in either plot type.
The demand for organic fruits and vegetables (F&V) is growing worldwide, creating market opportunities for developing countries as major suppliers. However, most export-oriented developing countries such as Chile have an undeveloped domestic market for organic products. This article identifies the segments of potential consumers of organic F&V in Central Chile using an exploratory CHAID model. A questionnaire was administered by surveying a random sample of 425 F&V consumers in central Chile. The results of the CHAID model suggest two segments of potential consumers of organic F&V. Both groups show awareness of the concept of organic food. Additionally, the first segment perceives organic agriculture to have ethical benefits to the society and considers organic F&V as healthy and nutritious; this group has a probability of over 80% to consume organic F&V. The second segment shows less awareness of the ethical benefits to society and its probability of consuming organic F&V depends on family income level. We discuss major implications for further studies on organic consumers.