Thermodynamic Impact of Mineral Surfaces on Amino Acid Polymerization: Aspartate Dimerization on Ferrihydrite, Anatase and γ-alumina

The ubiquity of amino acids in carbonaceous meteorites has suggested that amino acids are widespread in the Universe, serving as a common class of components for the emergence of life. However, parameters for modeling amino acid polymerization at mineral–water interfaces remain limited, although the interfacial conditions inevitably exist on planets with surface liquid water. Here, we present a set of extended triple-layer model parameters for aspartate (Asp) and aspartyl-aspartate (AspAsp) adsorptions on ferrihydrite, anatase, and γ-alumina determined based on the experimental adsorption data. By combining the parameters with the reported thermodynamic constants for amino acid polymerization in water, the impacts of these minerals on Asp dimerization are calculable over a wide range of environmental conditions. It was predicted, for example, that ferrihydrite strongly increases the AspAsp/Asp equilibrium ratio in neutral to acidic pH; the ratio in the adsorbed state reaches 40% even from a low Asp concentration (0.1 mM) at pH 4. This percentage is approximately 5 × 107 times higher than that attainable without mineral (8.5 × 10–6%). Our exemplified approach enables us to screen wide environmental settings for abiotic peptide synthesis from a thermodynamic perspective, thereby narrowing down the geochemical situations to be explored for life’s origin on Earth and Earth-like habitable planets.

A Bayesian analysis of hop price fluctuations

This paper quantifies the correlation between U.S. season average prices for hops with U.S. hop stocks and U.S. hop hectarage. The Hop Equilibrium Ratio, a measure of the supply/demand relationship for U.S. hops, was introduced. Through the Bayesian inference method, the authors used these data to calculate the effect an incremental change to one metric had on the probability of directional changes of future U.S. season average prices (SAP). Between 2010 and 2020, the dominance of proprietary varieties created unprecedented cartel-like powers offering opportunities for supply- and price-management. Research results will enable more accurate forecasting and greater price stability in the hop industry.

Challenges in Proofing of the Cyrillic MCVRO Resources – Equability between the Technical Component and the Role of the Researcher

The OCR process is a complex one and with interdisciplinary implications. This paper deals with old historical religious manuscripts and old books to offer solutions for the digitalization process. A high rate of success in the OCR process will help researchers from various fields to use relevant content and to value it in their research. When a research in the field of theology or history is conducted, there are many issues, especially when trying to access old manuscripts. There is no digitalized content to access old Romanian manuscripts and researchers need to learn specific old writing. The focus of the present study is on the problematic technical aspects that we encountered in our attempt to establish the equilibrium ratio between the instruments for the capitalization of the information and the contribution of the specialists in such research studies.

PHOTOTUNABLE SELECTIVE REFLECTION OF CHOLESTERIC LIQUID CRYSTALS

The dependence of the helical pitch of a cholesteric liquid crystal based on a composite photosensitive chiral dopant (cChD) on the intensity of light irradiation was studied. The transmission spectra and the selective reflection spectra of cholesteric liquid crystal cells were measured. The concentration of the cChD additive is calculated, so that the peak of selective reflection and its rearrangement occurs in the visible range of the electromagnetic radiation spectrum (380-780 nm). The possibility of photo-control by shifting the peak of the selective reflection of the cChD additive was studied, when exposed to LEDs with wavelengths of 365 nm and 450 nm, while reducing or increasing the intensity, a change in the spiral pitch was observed. Depending on the light intensity, part of the molecules of the chiral additive containing the azo group underwent isomerization, i.e. molecules in the trans-form passed to the cis-form, which led to a spectral shift of the selective reflection peak. If a small intensity of the 365 nm LED was applied, then some of the molecules were forced to transition from the trans- to the cis-form, and then, when illuminated with a 450 nm LED, from the cisto the trans-form. After reversible rearrangement, the properties of cholesteric liquid crystal changes due to interaction with light, because under the influence of light, the equilibrium ratio of the trans- and cis-isomers of the molecules of the substance changed, which macroscopically changed the torsion force of the chiral additive. Using two LEDs of 365 nm and 450 nm with different emission spectra, a reversible control of the cChD selective reflection peak in the visible range was obtained. The maximum displacement occurred at approximately 145 nm.

Compilation of Henry's law constants (version 4.0) for water as solvent

Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references. It is also available at http://www.henrys-law.org.

Compilation of Henry's law constants, version 3.99

Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 14775 values of Henry's law constants for 3214 species, collected from 639 references. It is also available on the internet at http://www.henrys-law.org.

Mechanism of cyclopropanol to cyclopropanol isomerization mediated by Ti(IV) and a Lewis acid

Isomerization of trans-3-deutero-r-1-methyl-cis-2-phenylcyclopropan-1-ol (1-trans-d) to three isomeric cyclopropanols was facilitated by reaction with a mixture of Ti(O-i-Pr)4 and BF3·OEt2. The more Lewis acidic Cl2Ti(O-i-Pr)2 catalyzed this reaction in the absence of BF3·OEt2. This cyclopropanol to cyclopropanol rearrangement involves reversible ring opening to a β-titanaketone. When the major species in solution prior to quenching was a titanium cyclopropoxide, a 40:40:10:10 mixture of cyclopropanols 1-trans-d:1-cis-d:2-trans-d:2-cis-d was obtained; this is close to the equilibrium ratio of the titanium cyclopropoxides. When a catalytic quantity of Ti(O-i-Pr)4 and a large excess of cyclopropanol was used, quenching gave a 29:29:21:21 mixture; this is closer to the equilibrium ratio of the cyclopropanols than the cyclopropoxides. Extrapolation to 0% and to 100% cyclopropoxide gave equilibrium constants for both cyclopropanols (Keq = [2]/[1] = 1.3) and cyclopropoxides (Keq = [2-Ti]/[1-Ti] = 0.18). A mechanism for these isomerization processes that involves ring opening and (or) ring closing with both retention and inversion of configuration at the carbon bearing phenyl is proposed.Key words: cyclopropanol, titanium isopropoxide, Kulinkovich hydroxycyclopropanation.