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Acta Chromatographica
Authors: M. Sajewicz, M. Gontarska, D. Kronenbach, E. Berry, and T. Kowalska

Summary

In our earlier studies, we were the first to discover a spontaneous chiral conversion of the low-molecular-weight carboxylic acids dissolved in aqueous media, running in vitro. The investigated chiral carboxylic acids belong to the classes of profen drugs, amino acids, and hydroxy acids. Then, the spontaneous chiral conversion running in vitro and accompanied by the spontaneous condensation of the discussed compounds was discovered. From the literature, we learnt that spontaneous condensation of certain chiral compounds sometimes can be oscillatory in nature. Thus, we considered it noteworthy to check if spontaneous condensation of the chiral low-molecular-weight carboxylic acids follows a linear or a nonlinear dynamic pattern. In this paper, we present the results of our studies on the dynamics of condensation of S-, R-, and rac-mandelic acid, carried out with the aid of the high-performance liquid chromatography with the diode-array detection (HPLC-DAD), and with the aid of mass spectrometry (MS). The obtained data furnish reliable evidence that condensation of mandelic acid is oscillatory in nature. Finally, a theoretical model is recalled, which jointly describes the oscillatory chiral conversion and the oscillatory condensation with S-, R-, and rac-mandelic acid.

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Introduction The diamine used is 2-(3,5-diaminophenyl)benzimidazole, DAPBI, and the dichloride is terephthaloyl chloride, TPC. The products are a polymer in the condensation under 1:1 of DAPBI:TPC mole ratio in feed. They are

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Determination of the gravimetric geoid is based on inversion of observed values of gravity into the disturbing gravity potential, i.e., the unknown potential is sought from discrete values of its vertical gradient. This transformation is often solved using boundary-value problems of the potential theory defined in terms of the Laplace differential equation and corresponding boundary conditions. However, this apparatus requires the potential function to be harmonic everywhere outside the boundary on which the unknown potential is solved for. For geoid determination, the boundary represents the geoid that is usually approximated for derivation of the solution by a geocentric sphere or reference ellipsoid. Since there are topographical and atmospheric masses outside the geoid, the potential function is not harmonic everywhere outside the geoid and the so-called reduction of the gravity potential and its functionals must be applied. This manuscript investigates the generalized method of Helmert’s condensation, namely its numerical implications for the standard procedure of geoid determination. An optimum location of the condensation layer is investigated from the point of relative smoothness of the gravity field and numerical difficulties with gravity inversion. The test area in the Canadian Rocky Mountains with a highly variable gravity field and topography is used for numerical investigations. Numerical results indicate that the condensation layer buried approximately 20–30 km inside the geoid gives the best results in terms of the gravity field smoothness as well as the complexity of gravity inversion. However, larger values of the primary indirect effect on the geoid for this depth of the condensed masses seem to overcome these numerical advantages.

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Acta Chromatographica
Authors: M. Sajewicz, M. Matlengiewicz, D. Kronenbach, M. Gontarska, and T. Kowalska

Summary

In a previous study we provided thin-layer chromatographic, polarimetric, and other experimental evidence that phenylglycine can undergo easy spontaneous peptidization in abiotic aqueous media. From our unpublished results it is apparent that this behaviour is also characteristic of some other amino acids (e.g., alanine and phenylalanine). It seems highly probable that this abiotic peptidization of amino acids dissolved in aqueous media is directly linked to their ability to undergo spontaneous oscillatory chiral conversion. In our earlier research it was also shown that spontaneous oscillatory chiral conversion was characteristic not only of amino acids but also of several other classes of carboxylic acid, including profen drugs and hydroxy acids. We therefore decided to check whether selected chiral hydroxy acids — lactic acid and mandelic acid — previously recognized for their ability to undergo spontaneous oscillatory chiral conversion, could also furnish the respective polyacids. Condensation of hydroxy acids can be viewed as a reaction fully analogous with peptidization of amino acids and, hence, it seemed to us highly probable that it also can be triggered by oscillatory chiral conversion. In our study, we used thin-layer chromatography and 13C NMR spectroscopy to check whether formation of polylactic acid and polymandelic acid occurred in stored solutions of lactic and mandelic acids. By means of polarimetry with continuous recording we provided experimental evidence that all three hydroxy acids investigated (i.e. l-(+)-lactic acid, S-(+)-mandelic acid, and R-(−)-mandelic acid) undergo continuous chiral conversion. From the thin-layer chromatographic results obtained it was apparent that — similar to the spontaneous and instantaneous peptidization of amino acids — the hydroxy acids investigated also undergo easy condensation to form the respective polyacids. 13C NMR spectroscopy provided additional experimental confirmation of this.

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The aim of this study was to test the explicitation hypothesis (Blum-Kulka 1986) on the morpho-syntactic level. A bi-directional comparable corpus of popular texts on history, as well as German and Czech parallel corpora were analysed in order to investigate the tendency in translations to use more explicit modes of expression instead of syntactic condensation devices. At the first stage of the study, the frequencies of finite verbs in main and subordinate clauses, participial phrases and infinitive constructions, and deverbative nouns and adjectives in original Czech and German texts were contrasted. Results showed that Czech prefers more verbal/explicit modes of expression in contrast with the more nominal/implicit German style. The second stage of the study consisted of the examination of explicitating and implicitating shifts in both German-to-Czech and Czech-to-German translations. The findings fully confirm the explicitation hypothesis, with explicitation exceeding implicitation by 40.6% in Czech and by 47.8% in German translations. The word count analysis also supports the hypothesis. At the third stage, translations were subjected to the same quantitative analysis as was conducted at stage one on original texts. The frequencies revealed in translations were then compared with those obtained from original target language texts. The German comparable corpus proved to have a higher degree of explicitness in translations while the Czech comparable corpus did not show any clear-cut explicitation tendencies in translations.

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Journal of Thermal Analysis and Calorimetry
Authors: T. Tahri, S. Abdul-Wahab, A. Bettahar, M. Douani, H. Al-Hinai, and Y. Al-Mulla

Abstract  

A theoretical model is formulated in this Part 1 of the paper for simulating the physical process of condensation of the humid air in the condenser of seawater greenhouse that is located in Muscat, Oman. Analyses to the equations, in addition to the theoretical developments of the proposed model are discussed.

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Acta Chromatographica
Authors: M. Matlengiewicz, M. Sajewicz, M. Gontarska, D. Kronenbach, and T. Kowalska

Summary

In a series of recently published full-length papers and short communications we attempted to gain deeper insight into elementary reactions which might contribute to the non-linear nature of the spontaneous chiral conversion of low-molecular-weight carboxylic acids. Earlier, we succeeded in demonstrating that amino acids and hydroxy acids can undergo spontaneous peptidization and spontaneous esterification (both regarded as condensation), respectively, when dissolved in 70% aqueous ethanol. In this study we provide experimental proof from thin-layer chromatography and 13C NMR spectroscopy of spontaneous condensation of profens, with ketoprofen as an example. It can be expected that other profen drugs undergo an analogous condensation. In the future, an analogy between the ability of amino acids, hydroxy acids, and profens to undergo spontaneous peptidization or condensation (as reported in our papers), and the ability of selected organosilanols to undergo the spontaneous oscillatory condensation (as reported elsewhere), might prove essential for better understanding of detailed mechanism of the spontaneous oscillatory in-vitro chiral conversion of the selected low-molecular-weight carboxylic acids.

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In recent years, surfaces of plaster facades increasingly have been covered with algae. This effect is reinforced by improved thermal insulation of the building.

Envelope e.g. due to the use of plastics, as well as the climate change and lower air pollution. The accumulation of condensation water is therefore of decisive importance.

So far, the amount of condensation water was determined with static weight methods. New developments in material research attempt to illustrate the susceptibility to condensation with different measurement methods. The differences can be seen in various systems and materials. Developing a model representation for the future planning of facades is thus possible for new and the existing building. This model can be used to derive new characteristics for new facade design.

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Journal of Flow Chemistry
Authors: Veronique Maes, Geert Pirotte, Jeroen Brebels, Pieter Verstappen, Laurence Lutsen, Dirk Vanderzande, and Wouter Maes

In this work, the synthesis of N,N’-dialkyl-6,6’-dibromoisoindigo derivatives by continuous-flow chemistry is explored as a means to enhance material availability and structural diversity, in particular toward the application of isoindigo-based semiconductors in high-performance organic photovoltaic devices. The individual steps in the conventional batch synthesis protocol are evaluated and, when needed, adapted to flow reactors. To overcome the low solubility of non-alkylated 6,6’-dibromoisoindigo in common organic solvents, the flow condensation reaction between the 6-bromo-isatin and 6-bromo-oxindole precursors is evaluated in polar aprotic solvents. Dialkylation of 6,6’-dibromoisoindigo is readily performed in flow using a solid-phase reactor packed with potassium carbonate. In an alternative strategy, solubility is ensured by first introducing the N-alkyl side chains on 6-bromo-isatin and 6-bromo-oxindole (accessible via a high-yielding flow reduction of alkylated 6-bromo-isatin), followed by condensation using the conventional method in acetic—hydrochloric acid medium. The N,N’-dialkylated 6,6’-dibromoisoindigo derivatives indeed show enhanced solubility in the hot reaction mixture compared to the non-alkylated material but eventually precipitate when the reaction mixture is cooled down. Nevertheless, the condensation between both alkylated starting materials is achieved in flow without any blockages by keeping the outlet from the reactor heated and as short as possible. The latter strategy allows the preparation of both symmetrically and asymmetrically N-substituted isoindigo compounds.

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Simulation of the condenser of the seawater greenhouse

Part II: Application of the developed theoretical model

Journal of Thermal Analysis and Calorimetry
Authors: T. Tahri, S. Abdul-Wahab, A. Bettahar, M. Douani, H. Al-Hinai, and Y. Al-Mulla

Abstract  

A theoretical model is developed in Part I of this study to simulate the physical process of condensation of the humid air in the condenser of an existing seawater greenhouse that is located in Muscat, Oman. Application is conducted in this part to validate the theoretical developments. Comparisons are made between the predictions and the existing experimental results. The results indicate that the comparison is well consistent. The effect of the relative humidity, the dry bulb temperature and the solar radiation are also discussed to see their effects on the condensate values.

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