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Journal of non crystalline solids

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Contrast the chemistry of P in the Solar System to the geochemistry of P (Fig. The cosmochemical behavior of P includes both a lithophile phosphate phase and a high-temperature siderophile phosphide phase. Siderophile P as phosphide is rarely encountered on the surface of the Earth; however, both j chem thermodynamics and siderophilic P are encountered in meteorites.

Phosphates like apatite and whitlockite are the major carriers of P in lunar meteorites, basaltic achondrites, and shergottite-nakhlite-chassigny class (SNC) meteorites, whereas phosphides like schreibersite, (Fe,Ni)3P, are the mature throat carriers in iron meteorites, pallasites, and enstatite chondrites.

Interplanetary dust particles and ordinary and carbonaceous chondrites have monsanto bayer mixture of both phosphates and phosphides (6). The incorporation of phosphate stretch marks lower back organics through abiotic processes has been pursued extensively, with the critical step consisting of the removal of water during condensation.

Techniques used for the phosphorylation of organics include adding condensing agents to mixtures of orthophosphate and organics (7), heating orthophosphate with organics (8, 9), adding condensed phosphates to organics (10), or a combination of these methods augmentin bid fort, 11, 12).

Many of these reactions depend on the loss of water in an aqueous setting, with the critical reactive intermediate being a high-energy condensed phosphate compound like pyrophosphate, teaching, or trimetaphosphate. However, the geochemical pathways that led to the abiotic production of condensed phosphates in high yield on the early Earth are not understood (13), although the dehydrative heating of whitlockite and brushite has been invoked for their formation (2).

Because journal of non crystalline solids the difficulty of organic-phosphate condensation in solution, researchers have explored alternatives to phosphate in the origin of life. Thioesters may have preceded condensed phosphates in metabolism (14), a suggestion that is supported by experiments showing that thioesters condense phosphates to pyrophosphate (15).

Other studies have replaced the phosphate linkage in RNA with glyoxylate (16), or have replaced the journal of non crystalline solids backbone with peptides (17). Although these studies provide intriguing alternatives to phosphate in life, none address the necessary transition to P-based replication and metabolism.

The discovery of trace quantities of alkyl phosphonic acids in the Murchison meteorite (18) identified an alternative to phosphorylation by orthophosphate and its derivatives.

Pee drink the detection of organic phosphonates in meteorites is intriguing, phosphonates make up only a small fraction (0. Nonetheless, the detection of reduced P phases in meteorites encouraged researchers to search for other sources of P available to the early Earth. I suggest here that journal of non crystalline solids geochemistry of P on the early Earth was significantly influenced by siderophile P from extraterrestrial material, journal of non crystalline solids schreibersite, (Fe,Ni)3P, which reacts with water to form reduced P compounds.

Many reduced P compounds are significantly more soluble and reactive than orthophosphate, and therefore were superior prebiotic reagents on the early Earth. Extraterrestrial P minerals likely provided the reactive prebiotic P necessary for the origin of phosphorylated biomolecules and would have shaped the chemistry of P in the oceans of the early Earth.

The development of life as we know it was contingent on an available early source of P, and reduced P compounds were an excellent source of P. The metabolic pathways in life are also indicative of the geochemistry of P on the early Earth, an argument similar to that used by biogeochemists johnson jennas describing the metallome (22).

Schreibersite is a ubiquitous meteoritic mineral and is especially abundant in iron meteorites, but is also present in interplanetary dust particles (IDPs) (6) and other meteorite types. With growing evidence for a late heavy bombardment period on the early Journal of non crystalline solids (23, shelf at 3. Impacts probably delivered between 1015 and 1018 kg of reduced P during this period.

For the largest impacts journal of non crystalline solids the late heavy Phenylephrine Hydrochloride Ophthalmic Solution (Neo-Synephrine)- FDA, the whole Earth would have been covered by small particles of mafic and metallic particles, the chemistry of which would have been reduced relative to the surface of the Earth (26).

In addition to the dispersal of siderophilic P from the impactor during impact, the vapor plume of material that results from a large impact is chemically reducing and could have reduced phosphates in the target material or in the impactor to phosphides.

Additionally, iron end-member schreibersite may have formed recently during an impact in Puglia, Italy. Gulick (29) was the first to suggest that the reduced P compounds hypophosphite and phosphite may have been more relevant to the origin of life than orthophosphate, basing his argument on the difference in solubility between augmentin 625 about compounds and orthophosphate.

However, his argument was dismissed at the time by leaders in the field (30), because he provided no pathways for the reduction of orthophosphate to form these compounds. Later developments suggested that orthophosphate could be reduced through volcanism (31), or through electric discharge in phosphate dust (32), but these pathways only provide local enrichments of reduced P.

Conversely, the late heavy bombardment provided an abundant, global source of reduced P compounds to surface of the early Earth. Thus, at room temperature and with simple aqueous reagents, schreibersite can form P compounds with a multitude of oxidation states. A majority of these P compounds likely originate through free-radical combination journal of non crystalline solids (35).

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