SEARCH · Search NASA

Results for “Aqueous synthesis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRS2005

RIO Tinto Faulted Volcanosedimentary Deposits as Analog Habitats for Extant Subsurface Biospheres on Mars: A Synthesis of the MARTE Drilling Project Geobiology Results

Geochemistry and mineralogy on Mars surface characterized by the MER Opportunity Rover suggest that early Mars hosted acidic environments in the Meridiani Planum region [1, 2]. Such extreme paleoenvironments have been suggested to be a regional expression of the global Mars geological cycle that induced acidic conditions by sulfur complexation and iron buffering of aqueous solutions [3]. Under these assumptions, underground reservoirs of acidic brines and, thereby, putative acidic cryptobiospheres, may be expected. The MARTE project [4, 5] has performed a drilling campaign to search for acidic and anaerobic biospheres in R o Tinto basement [6] that may be analogs of these hypothetical communities occurring in cryptic habitats of Mars. This Rio Tinto geological region is characterized by the occurrence of huge metallic deposits of iron sulfides [7]. Late intensive diagenesis of rocks driven by a compressive regimen [8] largely reduced the porosity of rocks and induced a cortical thickening through thrusting and inverse faulting and folding. Such structures play an essential role in transporting and storing water underground as any other aquifers do in the Earth. Once the underground water reservoirs of the Ro Tinto basement contact the hydrothermal pyrite deposits, acidic brines are produced by the release of sulfates and iron through the oxidation of sulfides [9].

Fernandez-Remolar, D. C.↗

NASA NTRS1991

A note on the prebiotic synthesis of organic acids in carbonaceous meteorites

Strong similarities between monocarboxylic and hydrocarboxylic acids in the Murchison meteorite suggest corresponding similarities in their origins. However, various lines of evidence apparently implicate quite different precursor compounds in the synthesis of the different acids. These seeming inconsistencies can be resolved by postulating that the apparent precursors also share a related origin. Pervasive D enrichment indicates that this origin was in a presolar molecular cloud. The organic acids themselves were probably synthesized in an aqueous environment on an asteroidal parent body, the hydroxy (and amino) acids by means of the Strecker cyanohydrin reaction.

Kerridge, John F.↗

NASA NTRS1983

New polymers for low-gravity purification of cells by phase partitioning

A potentially powerful technique for separating different biological cell types is based on the partitioning of these cells between the immiscible aqueous phases formed by solution of certain polymers in water. This process is gravity-limited because cells sediment rather than associate with the phase most favored on the basis of cell-phase interactions. In the present contract we have been involved in the synthesis of new polymers both to aid in understanding the partitioning process and to improve the quality of separations. The prime driving force behind the design of these polymers is to produce materials which will aid in space experiments to separate important cell types and to study the partitioning process in the absence of gravity (i.e., in an equilibrium state).

Harris, J. M.↗

NASA NTRS1972

Polymerization of amino acids under primitive earth conditions.

Small amounts of peptides were obtained when equal amounts of methane and ammonia were reacted with vaporized aqueous solutions of C14-labeled glycine, L-alanine, L-aspartic acid, L-glutamic acid and L-threonine in the presence of a continuous spark discharge in a 24-hr cyclic process. The experiment was designed to demonstrate the possibility of peptide synthesis under simulated primeval earth conditions. It is theorized that some dehydration-condensation processes may have taken place, with ammonium cyanide, the hydrogencyanide tetramer or aminonitriles as intermediate products, during the early chemical evolution of the earth.

Flores, J. J.↗

NASA NTRS2017

Thermal Studies of Ammonium Cyanide Reactions: A Model for Thermal Alteration of Prebiotic Compounds in Meteorite Parent Bodies

Organic compounds in carbonaceous chondrites were likely transformed by a variety of parent body processes including thermal and aqueous processing. Here, we analyzed ammonium cyanide reactions that were heated at different temperatures and times by multiple analytical techniques. The goal of this study is to better understand the effect of hydrothermal alteration on cyanide chemistry, which is believed to be responsible for the abiotic synthesis of purine nucleobases and their structural analogs detected in carbonaceous chondrites.

Hammer, P. G.↗

NASA NTRS2012

A 'Warm Formamide' Scenario for the Origins of Life Might Not Be so Hot Comment on 'Formamide and the Origin of Life' by E. Di Mauro Et Al.

In this review, Saladino et al. present an intriguing hypothesis surrounding the role of formamide in the originsof life on Earth, backed by experimental results supporting each step from formamide to RNA polymers [1]. The overall premise is that, from formamide and inorganic phosphate, RNA molecules over 100 nucleotides in length canbe produced. In addition, many carboxylic acids likely relevant to prebiotic metabolism are formed along the way. Thus, from a rather simple organic molecule that has been observed in outer space (formamide), you can generatemany of the compounds necessary for the origins of life. However, because high temperatures (160 C) are requiredfor the formamide reactions, it remains unclear where the warm formamide scenario could have occurred.Low-temperature, aqueous hydrogen counter to the observation that all protein-catalyzed ligation and polymerization reactions of RNA and DNA requireactivated substrates. Detailed mechanistic studies of the reported reactions are warranted and could provide important insights for understanding the chemistry behind the origins of life.Because the authors have produced many of the experimental results supporting their hypothesis, they coulddemonstrate the validity of their hypothesis by converting formamide into 100 nucleotide RNA oligomers, usingthe products of one reaction as the reactants for the next reaction, under specific conditions plausible on the pre-bioticEarth. Such a demonstration would represent a milestone for our understanding of the origins of life.cyanide-based prebiotic chemistry that we know actually happened has beenshown to produce many of the molecules invoked in the formamide hypothesis: amino acids, carboxylic acids, sugaracids, and nucleobases have all been found in meteorites recovered on Earth [e.g. [24]], providing a plausible routefor their synthesis and delivery. In contrast, a large portion of the formamide hypothesis is based on relatively high-temperature reactions. A plausible milieu for high-temperature reactions with concentrated formamide is yet to bedescribed, and is critical for this hypothesis to be validated. Hydrothermal vents are attractive heat sources, and the higher boiling point of formamide has been invoked as a mechanism to concentrate it from an aqueous solution.Unless the water can actually evaporate, however, there would be no net enrichment. For example, in the context of a deep-sea vent, any water removed by heating would be quickly replaced.Some of the individual reactions underpinning the present hypothesis [1] have been met with skepticism becausethey go against conventional wisdom. To name a few of the surprising results: the observation that nucleosides can beconverted to cyclic phosphates when heated in the presence of minerals and inorganic phosphate [5]; that 35 cGMPand cAMP nucleotides polymerize rapidly into RNA oligomers, even in the absence of monovalent counterions [6];and that end-to-end ligation reactions between RNA oligomers occur in essentially pure water, without requiring any activating groups or counterions [7,8]. Because the polymerization reactions are simply transesterification reactions,that they readily occur in the absence of cations makes one wonder why nearly all ribozyme-catalyzed transesterification reactions are metal-ion dependent; similarly, that the end-to-end ligation reactions do not require activation runs.

life↗

NASA NTRS1983

Prebiotic synthesis and reactions of nucleosides and nucleotides

The potential of diiminosuccinonitrile (DISN) as a prebiotic phosphorylating agent is studied. This compound is formed readily by the oxidation of diaminomaleonitrile, a tetramer of HCN. DISN is shown to produce the cyclization of 3'-adenosine monophosphate to adenosine 2',3'-cyclic phosphate in up to 40 percent yield. The DISN-mediated phosphorylation of uridine to uridine monophosphate is determined not to proceed efficiently in aqueous solution. The reaction of DISN and BrCN with uridine-5'-phosphate and uridine is found to result in the formation of 2,2'-anhydronucleotides and 2,2'-anhydronucleosides, respectively, and other reaction products resulting from an initial reaction at the 2' and 3'-hydroxyl groups. Homoionic montmorillonites were employed to study the clay mineral catalysis of the cyclization of adenosine-3'-phosphate.

Ferris, J. P.↗

NASA NTRS1997

Searching for Biogeochemical Cycles on Mars

The search for life on Mars clearly benefits from a rigorous, yet broad, definition of life that compels us to consider all possible lines of evidence for a martian biosphere. Recent studies in microbial ecology illustrate that the classic definition of life should be expanded beyond the traditional definition of a living cell. The traditional defining characteristics of life are threefold. First, life is capable of metabolism, that is, it performs chemical reactions that utilize energy and also synthesize its cellular constituents. Second, life is capable of self-replication. Third, life can evolve in order to adapt to environmental changes. An expanded, ecological definition of life also recognizes that life is a community of organisms that must interact with their nonliving environment through processes called biogeochemical cycles. This regenerative processing maintains, in an aqueous conditions, a dependable supply of nutrients and energy for growth. In turn, life can significantly affect those processes that control the exchange of materials between the atmosphere, ocean, and upper crust. Because metabolic processes interact directly with the environment, they can alter their surroundings and thus leave behind evidence of life. For example, organic matter is produced from single-carbon-atom precursors for the biosynthesis of cellular constituents. This leads to a reservoir of reduced carbon in sediments that, in turn, can affect the oxidation state of the atmosphere. The harvesting of chemical energy for metabolism often employs oxidation-reduction reactions that can alter the chemistry and oxidation state of the redox-sensitive elements carbon, sulfur, nitrogen, iron, and manganese. Have there ever been biogeochemical cycles on Mars? Certain key planetary processes can offer clues. Active volcanism provides reduced chemical species that biota can use for organic synthesis. Volcanic carbon dioxide and methane can serve as greenhouse gases. Thus the persistence of volcanism on Mars may well have influenced the persistence of a martian biosphere. The geologic processing of the crust can affect the availability of nutrients and also control the deposition of minerals that could have served as a medium for the preservation of fossil information. Finally, the activity of liquid water is crucial to life. Was there ever an Earth-like hydrologic cycle with rainfall? Has aqueous activity instead been restricted principally to hydrothermal activity below the surface? To what extent did the inorganic chemistry driven by sunlight and hydrothermal activity influence organic chemistry (prebiotic chemical evolution)? This paper addresses these and other key questions.

DesMarais, David J.↗

NASA NTRS1976

Abiotic origin of biopolymers

A variety of methods have been investigated in different laboratories for the polymerization of amino acids and nucleotides under abiotic conditions. They include (1) thermal polymerization; (2) direct polymerization of certain amino acid nitriles, amides, or esters; (3) polymerization using polyphosphate esters; (4) polymerization under aqueous or drying conditions at moderate temperatures using a variety of simple catalysts or condensing agents like cyanamide, dicyandiamide, or imidazole; and (5) polymerization under similar mild conditions but employing activated monomers or abiotically synthesized high-energy compounds such as adenosine 5'-triphosphate (ATP). The role and significance of these methods for the synthesis of oligopeptides and oligonucleotides under possible primitive-earth conditions is evaluated. It is concluded that the more recent approach involving chemical processes similar to those used by contemporary living organisms appears to offer a reasonable solution to the prebiotic synthesis of these biopolymers.

Oro, J.↗

NASA NTRS1981

Hydrazines and carbohydrazides produced from oxidized carbon in earth's primitive environment

Whether abiological organic compounds can be formed from the interactions of energy sources with nitrogen, oxidized carbon and water is held to be of importance in geochemical models of the primordial earth atmosphere. It is reported that experiments using quenched spark discharges through molecular nitrogen on aqueous suspensions of CaCO3 and other reactants to simulate the hydrosphere/atmosphere interface yield hydrazine and carbohydrazine in significant but low yields. Such reactions in primitive aquatic environments may have supplied a pathway for chemical evolution and the origin of life, on a primitive earth in which fully oxidized states of carbon were available for the primary synthesis of organic matter.

Folsome, C. E.↗

NASA NTRS1991

Kinetics of the template-directed oligomerization of guanosine 5'-phosphate-2-methylimidazolide: Effect of temperature on individual steps of reactionion

Non-enzymatic, template-directed reactions have been proposed as models for prebiological polynucleotide synthesis. Chemically activated mononucleotides react in the presence of a polynucleotide, acting as the template in a Watson-Crick base-pairing fashing, and form the complementary daughter polynucleotide. Phosphoimidazolide-activated nucleotides have been used successfully as substrates in these reactions. The kinetics of the guanosine 5'-monophosphate-2-methylimidazolide (2-MelmpG) reaction in aqueous pH 8.0 solutions in the presence and in the absence of polycytidylate (poly(C)) were studied, acting as the template at 6, 23, and 37 C. In the absence of the template, the major reaction pathway of 2-MelmpG is hydrolysis of the P-N bond to form the unreactive guanosine 5'-monophosphate (5'-GMP) and 2-methylimidazole. Concentrated solution of 2-MelmpG (greater than 0.02 M) in the absence of the template form only a small amount dinucleotide, (pG)2, but in the presence of poly(C), oligoguanylates, (pG)n with 2 less than or = n less than or = 40, can be detected. We were able to determine the rate constants for individual steps of this reaction. A summary of the conclusions is presented.

Kanavarioti, A.↗

NASA NTRS1976

Formation of nucleoside 5'-polyphosphates under potentially prebiological conditions

The characteristics and efficiencies of biochemical reactions involving nucleoside 5'-diphosphates and -triphosphates (important substrates of RNA and DNA synthesis) under conditions corresponding to the primitive prebiotic earth are investigated. Urea catalysis of the formation of linear inorganic polyphosphates and metal ions promoting the reactions are discussed. Linear polyphosphate was incubated with Mg(++) in the presence of a nucleoside 5'-phosphate, to yield nucleoside 5'-polyphosphates when products are dried, while Mg(++) prompts depolymerization to trimetaphosphate in aqueous solutions. Plausible biogenetic pathways are examined.

Lohrmann, R.↗

NASA NTRS1993

Synthesis of novel electrically conducting polymers: Potential conducting Langmuir-Blodgett films and conducting polymers on defined surfaces

Based on previous results involving thiophene derived electrically conducting polymers in which it was shown that thiophene, 3-substituted thiophenes, furans, and certain oligomers of these compounds showed electrical conductivity after polymerization. The conductivity was in the order of up to 500 S/cm. In addition, these polymers showed conductivity without being doped and most of all they were practically inert toward ambient conditions. They even could be used in aqueous media. With these findings as a guide, a number of 3-long-chain-substituted thiophenes and 1-substituted-3-long-chain substituted pyrrols were synthesized as monomers for potential polymeric electrically conducting Langmuir-Blodgett films.

Zimmer, Hans↗

NASA NTRS2019

Prebiotic Chemistry of Pluto

We present the case for the presence of complex organic molecules, such as amino acids and nucleobases, formed by abiotic processes on the surface and in near-subsurface regions of Pluto. Pluto's surface is tinted with a range of non-ice substances with colors ranging from light yellow to red to dark brown; the colors match those of laboratory organic residues called tholins. Tholins are broadly characterized as complex, macromolecular organic solids consisting of a network of aromatic structures connected by aliphatic bridging units (e.g., Imanaka et al.,2004; Materese et al.,2014, 2015). The synthesis of tholins in planetary atmospheres and in surface ices has been explored in numerous laboratory experiments, and both gas- and solid-phase varieties are found on Pluto. A third variety of tholins, exposed at a site of tectonic surface fracturing called Virgil Fossae, appears to have come from a reservoir in the subsurface. Eruptions of tholin-laden liquid H2O from a subsurface aqueous repository appear to have covered portions of Virgil Fossae and its surroundings with a uniquely colored deposit (D.P. Cruikshank, personal communication) that is geographically correlated with an exposure of H2O ice that includes spectroscopically detected NH3 (C.M. Dalle Ore, personal communication). The subsurface organic material could have been derived from presolar or solar nebula processes, or might have formed in situ. Photolysis and radiolysis of a mixture of ices relevant to Pluto's surface composition (N2, CH4, CO) have produced strongly colored, complex organics with a significant aromatic content having a high degree of nitrogen substitution similar to the aromatic heterocycles pyrimidine and purine (Materese et al.,2014, 2015; Cruikshank et al.,2016). Experiments with pyrimidines and purines frozen in H2O-NH3 ice resulted in the formation of numerous nucleobases, including the biologically relevant guanine, cytosine, adenine, uracil, and thymine (Materese et al.,2017). The red material associated with the H2O ice may contain nucleobases resulting from energetic processing on Pluto's surface or in the interior. Some other Kuiper Belt objects also exhibit red colors similar to those found on Pluto and may therefore carry similar inventories of complex organic materials. The widespread and ubiquitous nature of similarly complex organic materials observed in a variety of astronomical settings drives the need for additional laboratory and modeling efforts to explain the origin and evolution of organic molecules. Pluto observations reveal complex organics on a small body that remains close to its place of origin in the outermost regions of the Solar System.

Cruikshank, D. P.↗

NASA NTRS1984

Purification of biomaterials by phase partitioning

A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.

Harris, J. M.↗

NASA NTRS2016

Low Temperature Regolith Bricks for In-Situ Structural Material

Current technology for producing in-situ structural materials on future missions to Mars or the moon relies heavily on energy-intensive sintering processes to produce solid bricks from regolith. This process requires heating the material up to temperatures in excess of 1000 C and results in solid regolith pieces with compressive strengths in the range of 14000 to 28000 psi, but are heavily dependent on the porosity of the final material and are brittle. This method is currently preferred over a low temperature cementation process to prevent consumption of precious water and other non-renewable materials. A high strength structural material with low energy requirements is still needed for future colonization of other planets. To fulfill these requirements, a nano-functionalization process has been developed to produce structural bricks from regolith simulant and shows promising mechanical strength results. Functionalization of granular silicate particles into alkoxides using a simple low temperature chemical process produces a high surface area zeolite particles that are held together via inter-particle oxygen bonding. Addition of water in the resulting zeolite particles produces a sol-gel reaction called "inorganic polymerization" which gives a strong solid material after a curing process at 60 C. The aqueous solution by-product of the reaction is currently being investigated for its reusability; an essential component of any ISRU technology. For this study, two batches of regolith bricks are synthesized from JSC-1A; the first batch from fresh solvents and chemicals, the second batch made from the water solution by-product of the first batch. This is done to determine the feasibility of recycling necessary components of the synthesis process, mainly water. Characterization including BET surface area, SEM, and EDS has been done on the regolith bricks as well as the constituent particles,. The specific surface area of 17.53 sq m/g (average) of the granular regolith material was obtained from nitrogen adsorption isotherm measurement. The size, shape and textures of regolith from SEM shows that the particles are 25-50 micrometers in size and mostly irregular in shape (Figure 1a). The elemental composition of regolith was identified from EDS analysis showed the presence of Si, Al, Fe, Na, Mg, Ca, Ti, O and C (see figure 1b). Each set of cylindrical brick samples were prepared by low energy process, and cured for 21 and 28 days, respectively to compare their compressive strength. Figure 1c, and d shows the JSC-1A brick and the compressive strength measurements. The results from the 21 day cured bricks (2 bricks) have been done and yielded an aver-age strength of 3050 psi, considerably higher than Portland cement mortars (Type IV and V). This promising technology provides the benefits of construction material similar to concrete, with a low complexity, low energy synthesis process and the likelihood of complete reusability of precious resources. Compressive strength using this method can be improved by increasing the surface area of the particles, using bi-modal particle size distribution, and adding certain additives to increase inter-particle forces.

ISRU↗

NASA NTRS1981

Terrestrial evolution of polymerization of amino acids - Heat to ATP

Sets of amino acids containing sufficient trifunctional monomer are thermally polymerized at temperatures such as 65 deg; the amino acids order themselves. Various polymers have diverse catalytic activities. The polymers aggregate, in aqueous solution, to cell-like structures having those activities plus emergent properties, e.g. proliferatability. Polyamino acids containing sufficient lysine catalyze conversion of free amino acids, by ATP, to small peptides and a high molecular weight fraction. The lysine-rich proteinoid is active in solution, within suspensions of cell-like particles, or in other particles composed of lysine-rich proteinoid and homopolyribonucleotide. Selectivities are observed. An archaic polyamino acid prelude to coded protein synthesis is indicated.

Fox, S. W.↗

NASA NTRS1986

Intramolecular interactions in aminoacyl nucleotides: Implications regarding the origin of genetic coding and protein synthesis

Cellular organisms store information as sequences of nucleotides in double stranded DNA. This information is useless unless it can be converted into the active molecular species, protein. This is done in contemporary creatures first by transcription of one strand to give a complementary strand of mRNA. The sequence of nucleotides is then translated into a specific sequence of amino acids in a protein. Translation is made possible by a genetic coding system in which a sequence of three nucleotides codes for a specific amino acid. The origin and evolution of any chemical system can be understood through elucidation of the properties of the chemical entities which make up the system. There is an underlying logic to the coding system revealed by a correlation of the hydrophobicities of amino acids and their anticodonic nucleotides (i.e., the complement of the codon). Its importance lies in the fact that every amino acid going into protein synthesis must first be activated. This is universally accomplished with ATP. Past studies have concentrated on the chemistry of the adenylates, but more recently we have found, through the use of NMR, that we can observe intramolecular interactions even at low concentrations, between amino acid side chains and nucleotide base rings in these adenylates. The use of this type of compound thus affords a novel way of elucidating the manner in which amino acids and nucleotides interact with each other. In aqueous solution, when a hydrophobic amino acid is attached to the most hydrophobic nucleotide, AMP, a hydrophobic interaction takes place between the amino acid side chain and the adenine ring. The studies to be reported concern these hydrophobic interactions.

Lacey, J. C., Jr.↗