Shechtman’s three question marks: possibility, impossibility, and quasicrystals

The revolutionary discovery of actual quasicrystals, thanks to Dan Shechtman’s stamina, is a golden opportunity to analyze once again the role that pure (“theoretical”) possibilities and saving them plays in scientific progress. Some theoreticians, primarily Alan Mackay, contributed to saving pure possibilities of quasicrystalline structures and to opening materials science for them. My analysis rests upon an original modal metaphysics—panenmentalism—which I introduced and have been developing since 1999, quite independently of any familiarity with modern crystallography, and which deals with saving pure possibilities as indispensably contributing, inter alia, to our knowledge and sciences.     

Tellurites of some s–f elements: Synthesis, X-ray diffraction, and electrophysical properties

A possibility of solid-phase synthesis of new cerium double tellurites with s-elements from the oxides of cerium(IV), tellurium(IV) and magnesium (calcium, strontium) carbonates was demonstrated. It was determined by the X-ray diffraction method that the magnesium-cerium tellurite crystallizes in a cubic system, while calcium-cerium and strontium-cerium tellurites crystallize in the tetragonal crystal system.The temperature dependence of the electrical resistance of these compounds in the range of 300?C600 K was measured. The plots include sharp anomalous jumps due probably to the phase transitions of type II.     

Co-doped ZnO nanoparticles synthesized by an adapted sol–gel method: effects on the structural,optical, photocatalytic and antibacterial properties

Pure and Co-doped ZnO nanoparticles were synthesized with different cobalt levels (1–10 mol%) via adapted sol–gel method using water as solvent and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoacoustic absorption spectroscopy. The results showed that all the samples have hexagonal wurtzite structure, with no evidence of any secondary phases until 10 mol% of the dopant. The average crystallite size of the samples was in the range of 25–50 nm, do not showing significant differences with the increase of the dopant level. However, the band gap energy of the nanoparticles decreases from 2.98 eV (pure ZnO) to 1.95 eV (10 mol% of Co). The photocatalytic activity of the samples was evaluated on the removal of methylene blue under visible light irradiation, which revealed an efficiency reduction by Co-doping ZnO. The antibacterial property was carried out indicating activity of the prepared samples against gram-positive bacteria.     

Synthesis, structure, and properties of a new phosphorus-containing Schiff’s base, a derivative of pyrazole-5-one

A new Schiff’s base and its salt have been prepared from 2-aminophenyl(triphenyl)phosphonium chloride and 5-hydroxy-3-methyl-1-phenyl-4-formylpyrazole. The products structures have been proved by IR, ¹H NMR, and UV spectroscopy, mass spectrometry, X-ray diffraction analysis, and quantum-chemical modeling. Possible tautomerism and some properties of the products have been studied.     

New diorganotin(IV) complexes with some Schiff bases derived from β-diketones: synthesis,spectral properties,thermal analysis,and antibacterial activity

The Schiff bases H₂L^a, H₂L^b, and H₂L^c have been prepared from the reaction of 2-amino-4-chlorophenol with acetylacetone, benzoylacetone, and dibenzoylmethane, respectively. Organotin(IV) complexes [SnPh₂(L^a)] (1), [SnPh₂(L^b)] (2), [SnPh₂(L^c)] (3), and [SnMe₂(L^c)] (4) have been synthesized from the reaction of SnPh₂Cl₂ and SnMe₂Cl₂ with these Schiff bases. The synthesized complexes have been characterized by elemental analysis and FT-IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy. Spectroscopic data suggest the Schiff bases are completely deprotonated and coordinated tridentate to tin via imine nitrogen and phenolic and enolic oxygen atoms; the coordination number of tin is five. Thermal decomposition of the complexes has been studied by thermogravimetry. The in vitro antibacterial activities of the Schiff bases and their complexes have been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. H₂L^a, H₂L^c, and all complexes exhibited good activities and have potential as drugs.     

Chemical characterization,antioxidant properties and enzyme inhibition of Rutabaga root’s pulp and peel (Brassica napus L.)

Rutabaga (Brassica napus L.) belonging to Brassicaceae family, is a rich source of polyphenols and glucosinolates. Its consumption in human diet is highly appreciated for its nutritional contribution and health benefits. Brassica napus L. is recognized as the world's most widely grown temperate oilseed crop containing erucic acid for industrial applications, plants germination, animal feed and fuel. In this work we prepared two different extracts of Rutabaga root’s pulp and peel, e.g. ultrasound assisted extract (UAE) and homogenizer assisted extract (HAE). The four extracts have been analyzed by HPLC-MS to assess the phytochemical characterization and tested by antioxidant and enzyme inhibitor assays. Rutabaga pulp and peel extracts possess tyrosinase and glucosidase inhibitory activities together with a moderate antioxidant ability. Our results show a high level of glucosinolates, in particular neoglucobrassicin in the peel extract, which let us suppose a potential application as crop in industry and as supplement in human diet.     

Carbenes,related intermediates,and small-sized cycles: contribution from Professor Nefedov’s laboratory

The review summarizes some of the most prominent results obtained in the laboratory headed by Academician Oleg M. Nefedov at the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences in the field of chemistry of carbenes, their heavy analogs, and related intermediates, as well as small-sized cycles. Those include elaboration of safe methodology of cyclopropanation using diazomethane, development and extension of synthetic applications of diazoesters and other diazo compounds in the preparation of valuable chemical products, design of functionalized alkynylcyclopropanes on the basis of alkynylcarbene reactions, creation of versatile synthetic approaches to preparation of various practically useful fluoroorganic compounds on the basis of reactions of fluorocarbenes, development of synthetic applications of heavy carbene analogs and synthesis of small-sized heterocycles containing silicon and germanium atoms, analysis of mechanisms of some important reactions of carbenes, their analogs and related intermediates on the basis of physicochemical studies, direct spectroscopic studies of various labile intermediates of chemical reactions.     

Chemistry of HCNH+: mechanisms, structures, and relevance to Titan’s atmosphere

The chemistry of HCNH⁺ in Titan’s atmosphere is not completely understood despite previous experimental and theoretical studies. In response to recent suggestions in the literature, we have searched for specific products of the reactions of HCNH⁺ with H₂, CH₄, C₂H₂, and C₂H₄ using the flowing afterglow-selected ion flow tube technique. We have probed for an association mechanism for reaction with H₂, and associative-H₂ loss for the reactions involving CH₄, C₂H₂, and C₂H₄. In all cases, these reaction mechanisms were found to be inefficient pathways for the depletion of HCNH⁺. Our ab initio computational studies characterize the structures and energies for these mechanisms and indicate that the proposed pathways are endothermic or possess reaction barriers. We compare our studies to previous experimental and computational work, and we suggest other ion-neutral reactions with HCNH⁺ that have not been included in previous models of Titan’s ionosphere.     

Wilhelm Ostwald’s energetics 3: energetic theory and applications,part II

This is the third of a series of essays on the development and reception of Wilhelm Ostwald’s energetics. The first essay described the chemical origins of Ostwald’s interest in the energy concept and his motivations for seeking a comprehensive science of energy. The second essay and the present one discuss his various attempts, beginning in 1891 and extending over almost 3 years, to develop a consistent and coherent energetic theory. A final essay will consider reactions to this work and Ostwald’s replies, and will also seek to evaluate his program of research. Ostwald’s project—to reconstruct physics and chemistry “as a pure energetics”—is worth attending to for several reasons: first, because Ostwald did ground-breaking work in chemistry (he was awarded a Nobel Prize in 1909 for his studies in catalysis and rates of reaction); second, because an important school of physical chemistry formed around him at Leipzig, a school that promoted his ideas; and, finally, because he was a prominent and vigorous participant in debates at the end of the nineteenth century concerning the proper course of physical theory.

Enantioresolution of Amino Acids: A Decade’s Perspective,Prospects and Challenges

Both from academic and industrial points of view enantioseparation of dl-amino acids continues to be a subject of immense importance and enjoys a great analytical significance in various fields, such as in the studies of fossils, origin of life, disease diagnosis, quality of food and beverages, etc. The present paper is a topical collection of recent advances along with a discussion on possible challenges in chiral amino acid analysis and is intended to present the existing state of knowledge on the topic as a particular facet of chromatography (and electrophoretic techniques). It presents a critical overview of the state-of-the-art of the topic, with critically selected examples to point the reader to trends and likely future developments and to give a selection of important references to the current literature.

     

Optical and nonlinear optical properties of new Schiff’s bases: experimental versus theoretical study of inclusion interactions

Experimentally and theoretically were studied the physical properties of 19 new Schiff’s bases and their different protonated forms, depending on reaction conditions. It was elucidated the correlation between the type of molecular architecture, substituents and pH of the medium on first hyperpolarizability (β) with regard to the potential application of these compounds as organic nonlinear optical materials. The structure and optical properties were also studied, comparing quantum chemical data and experimental results from the mass spectrometry, electronic absorption, diffuse reflectance, and fluorescence spectroscopy, vibrational spectroscopy in condense phase, nuclear magnetic resonance, as well as thermal methods.     

The impact of measurement uncertainty on the producer’s and user’s risks, on classification and conformity assessment: an example based on tests on some construction products

The reliability of test results and subsequent classification statements or product certification depend on the variability of the product’s properties and on the validity of the test procedures used. With an emphasis on measurement uncertainty, producer’s and user’s risks as well as probabilities of conformance, conformity and classification are calculated exemplarily for two requirements for mineral aggregates used in construction. An important methodological basis is an international draft document on measurement uncertainty in conformity assessment. The mathematical instruments given are applied and further developed to a risk scenario for product classification. The results from a classification point of view show that the reliability of test results for acid-soluble sulphates is mostly acceptable and both the producer’s and user’s risks are quite small. In contrast, the magnesium sulphate index test produces results which are hardly usable for classification and certification purposes or for risk management in production. Product certification bodies should generally have an appropriate approach when dealing with results where precision data are poor.     

Preparation of sol–gel based nano-structured hybrid coatings: effects of combined precursor’s mixtures on coatings morphological and mechanical properties

Nanostructured hybrid clearcoats were produced using sol–gel based organic/inorganic precursors. To this end, clearcoats containing mixtures of a network former (tetraethyl ortosilicate; TEOS) and a network modifier (methacryloxy propyltrimethoxysilane; MEMO) and their hydrolyzed forms were prepared. Scanning electron microscope and atomic force microscope were utilized in order to investigate the morphology of different sol–gel prepared films. The mechanical properties of the bulk and surface of the clearcoats were studied by dynamic mechanical thermal analysis and nanoindentation techniques. The scratch resistance of the hybrid clearcoats was also studied by a laboratory carwash simulator. Decrease in glass transition temperature (Tg), cross-linking density, hardness and elastic modulus were seen for the clearcoat composed of hydrolyzed network modifier combined with hydrolyzed and non-hydrolyzed network former. However, a reverse effect was seen when the hydrolyzed TEOS and non-hydrolyzed MEMO was used. No improvement was observed using hydrolyzed MEMO in the clearcoat composition. Generally, results revealed improved mechanical properties of the clearcoat when the hydrolyzed network former was used together with non-hydrolyzed MEMO. Greater phase separation and silica cluster formation were seen for the clearcoats loaded with hydrolyzed MEMO compared with hydrolyzed TEOS.     

Organic environments on Saturn’s moon,Titan: Simulating chemical reactions and analyzing products by FT-ICR and ion-trap mass spectrometry

Laboratory simulations have been carried out to model chemical reactions that possibly take place in the stratosphere of Saturn's moon, Titan. The aerosol products of these reactions (tholin samples) have been systematically analyzed by mass spectrometry using electrospray ionization (ESI) and laser desorption (LD). A wide variety of ions with a general formula C(x)H(y)N(z) detected by ultrahigh resolution and accurate mass measurements in a Fourier transform/ion cyclotron resonance (FT-ICR) cell reflect the complexity of these polymeric products, both in chemical compositions and isomeric distributions. As a common feature, however, tandem mass spectral (MS/MS) data and H/D exchange products in the solution phase support the presence of amino and nitrile functionalities in these (highly unsaturated) "tholin" compounds. The present work demonstrates that ESI-MS coupled with FT-ICR is a suitable and "intact" method to analyze tholin components formed under anaerobic conditions; only species with C(x)H(y)N(z) are detected for freshly prepared and harvested samples. However, when intentionally exposed to water, oxygen-containing compounds are unambiguously detected.     

Binuclear metallochelates of 2-(N-tosylamino)benzal-2’-(hydroxymethyl)aniline: Syntheses,structures, and magnetic properties

Binuclear complexes of Co(II), Сu(II), and Pd(II) with 2-(N-tosylamino)benzal-2’-(hydroxymethyl)aniline are synthesized. The compositions and structures of the ligand and complexes are determined from the data of elemental analysis, IR spectroscopy, ¹Н, ¹³С, and ¹⁵N NMR spectroscopy, X-ray absorption spectroscopy, and magnetochemical measurements in a temperature range of 294–77.4 K. All complexes are dimeric. The Cu…Cu and Cо…Cо distances equal to 3.03 and 2.99 Å, respectively, are obtained for the Cu(II) and Co(II) complexes. These complexes are characterized by the antiferromagnetic exchange interaction with 2J = –630 and –42 cm^–1, respectively.     

Two Zn(II) coordination polymers based on 1,3-di(4’-carboxyl-phenyl)benzene and N-donor coligands: syntheses,crystal structures,and luminescent properties

Two coordination polymers, {[Zn(dpb)(3-bpmp)_0.5]·1.5(DMF)}_n (1) and [Zn(dpb)(4-bpmp)]_n (2) (H₂dpb = 1,3-di(4′-carboxyl-phenyl)benzene, 3-bpmp = 1,4-bis(3-pyridylmethy)piperazine, 4-bpmp = 1,4-bis(4-pyridylmethy)piperazine and DMF = N,N-dimethylformamide), were solvothermally synthesized and characterized. Tuning the difference of N-donor ligands, we obtained 1 and 2 which display different topological nets. Complex 1 features a 6-connected topological net and 2 shows a 4-connected three-fold interpenetrated framework. Luminescent properties of 1 and 2 are investigated at room temperature.     

Baker’s yeast: An efficient,green, and reusable biocatalyst for the one-pot synthesis of biologically important N-substituted decahydroacridine-1,8-dione derivatives

A green approach for one-pot three-component synthesis of N-substituted decahydroacridine-1,8-diones is offered for the first time using baker’s yeast (Saccharomyces cerevisiae) as a biocatalyst under ultrasonication. Due to growing safety and environmental concerns, enzymatic methods were constantly investigated as an attractive alternative to toxic and nonspecific chemical approaches. This method is relatively simple, efficient, inexpensive, and environment-friendly. The catalyst was recovered and reused and also the recyclability of baker’s yeast resulted in excellent yields of products without loss of any catalytic activity.