Luminescence database I--minerals and materials.

A luminescence database for minerals and materials has been complied from the literature, the aim being to create a resource that will aid in the analysis of luminescence spectral of ionic species in minerals and materials. The database is based on a range of excitation techniques and records both major and minor lines, and their activators. The luminescence techniques included in the database are cathodoluminescence, ion luminescence, and photoluminescence. When combined with other traditional X-ray measurements collected on the same region, use of the luminescence database will give additional insight into the chemistry of minerals and materials.     

Developing drug literatures. 1. Bibliometrics of baclofen and dantrolene sodium.

The literatures of two antispastic drugs, baclofen and dantrolene sodium, were studied bibliometrically for their first decade and were found to be generally similar. Baclofen had 93 papers and dantrolene sodium had 70. About a quarter of the baclofen papers were in a foreign language, whereas almost all dantrolene sodium papers were in English. Baclofen literature had a lower nonscholarly content, but the scholarly increase, 5%, was the same for both. Both drugs had an average of 12 references per paper. The literatures of both drugs had a similar degree of internal cohesiveness; almost half of their papers referred to other papers in the same drug collection. The first human paper for baclofen was the second published; for dantrolene sodium, it was the eleventh. The distribution of journals carrying papers on each of these drugs followed Bradford's law. Two authors per paper was the average for each drug. The productivity of authors approximated Lotka's law for both drugs. About two-thirds of the papers of both drugs had a drug-word in their titles. The literature of both drugs contained about 15% legendary papers, typical of clinical pharmacology. The most intense papers, 15 for baclofen and 11 for dantrolene sodium, were identified, using citation, bibliographic coupling, and co-citation frequencies. A generalization predicts what might be expected from the literature of future antispastic drugs.     

Effects of surface structure on the molecular projection area. Adsorption of argon and nitrogen onto defective surfaces

This paper studies the effects of surface structure (defective surfaces) on the molecular projection area of argon and nitrogen at 77 K. The determination of the molecular projection area is based on choice of the surface area of the structure studied and the adsorption data obtained from the GCMC simulation. Two methods were used to determine the surface area: the flat surface area that are commonly used in the literature and the geometrical surface area. The molecular projection areas of argon and nitrogen at 77 K vary with pressure over the recommended range for BET plot (reduced pressures from 0.05 to 0.3) and also they varies with the percentage of defects on the surface. Additionally, it is seen that the geometrical surface area method gives molecular projection area of defective surfaces values that are in accordance with the experimental value reported in the literature.     

Analysis of industrial contaminants in indoor air. Part 2. Emergent contaminants and pesticides

This article reviews recent literature on the analysis of several contaminants related to the industrial development in indoor air in the framework of the REACH project. In this second part, the attention is focused on emergent contaminants and biocides. Among these chemicals, phthalates, polybrominated and phosphate flame retardants, fragrances, pesticides, as well as other emerging pollutants, are increasing their environmental and health concern and are extensively found in indoor air. Some of them are suspected to behave as priority organic pollutants (POPs) and/or endocrine disrupting compounds (EDC), and can be found both in air and associated to the suspended particulate matter (PM) and settled dust. Main literature considered for this review is from the last ten years, reporting analytical developments and applications regarding the considered contaminants in the indoor environment. Sample collection and pretreatment, analyte extraction or desorption, clean-up procedures, determination techniques, and performance results are summarized and discussed.     

High-conversion polymerization. I. Theory and application to methyl methacrylate

The concept of polymer entanglements has been applied in conjunction with classical free-radical kinetics to describe vinyl polymerizations carried to high conversion. A kinetic model has been developed on the assumption that two populations of radicals exist in a high-conversion polymerization system: those radicals whose chain lengths are long enough to become entangled with neighboring molecules and have, therefore, a restricted mobility; and those shorter radicals whose mobilities are not strongly affected by diffusional effects. It has also been assumed that the kinetic rate constant for the termination step between entangled radicals is inversely proportional to the mean entanglement density. The model contains only two parameters in addition to the kinetic rate constants required to describe low-conversion polymerizations. One of these parameters can be determined, at least in principle, from measurements of solution properties of the polymer-monomer mixtures. The model so developed has been tested against experimental data obtained from the literature on the bulk polymerization of methyl methacrylate. The agreement between predicted and experimental monomer conversions and molecular weight averages is found to be satisfactory.     

Thermodynamic quantities for propane 3. The thermodynamic behaviour of saturated and compressed liquid propane

In an isochoric study the thermodynamic behaviour of liquid propane was experimentally investigated. Measurements were performed along six isochores with reduced densities from 2.0 to 2.5 at pressures up to 60 MPa. Additional measurements were carried out along the saturated-liquid curve. These results were critically examined and compared with results from the literature. The most reliable measurements were used to established a new equation of state for liquid propane of the Strobridge-type and new Wagner-type equations for vapour pressures and saturated-liquid densities, respectively. In addition isochoric and isobaric heat capacities were evaluated as well as ultrasonic speeds that agree with measurements from the literature to within their experimental uncertainty.     

Nigella sativa L. and COVID-19: A Glance at The Anti-COVID-19 Chemical Constituents,Clinical Trials,Inventions, and Patent Literature

COVID-19 has had an impact on human quality of life and economics. Scientists have been identifying remedies for its prevention and treatment from all possible sources, including plants. Nigella sativa L. (NS) is an important medicinal plant of Islamic value. This review highlights the anti-COVID-19 potential, clinical trials, inventions, and patent literature related to NS and its major chemical constituents, like thymoquinone. The literature was collected from different databases, including Pubmed, Espacenet, and Patentscope. The literature supports the efficacy of NS, NS oil (NSO), and its chemical constituents against COVID-19. The clinical data imply that NS and NSO can prevent and treat COVID-19 patients with a faster recovery rate. Several inventions comprising NS and NSO have been claimed in patent applications to prevent/treat COVID-19. The patent literature cites NS as an immunomodulator, antioxidant, anti-inflammatory, a source of anti-SARS-CoV-2 compounds, and a plant having protective effects on the lungs. The available facts indicate that NS, NSO, and its various compositions have all the attributes to be used as a promising remedy to prevent, manage, and treat COVID-19 among high-risk people as well as for the therapy of COVID-19 patients of all age groups as a monotherapy or a combination therapy. Many compositions of NS in combination with countless medicinal herbs and medicines are still unexplored. Accordingly, the authors foresee a bright scope in developing NS-based anti-COVID-19 composition for clinical use in the future.     

Dihydrothiophenes. Synthesis and properties (review)

The literature data on the methods of synthesis and properties of 2,3-dihydrothiophene and 2,5-dihydrothiophene have been correlated for the first time. A. N. Kosygin Moscow State Textile Academy, Moscow 117918, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1324, October, 1998.     

Homopolar- and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase. I. Data on organic molecules

The literature data on heteropolar and homopolar 2-center bond dissociation energies in organic molecules in the gas phase and the corresponding heats of formation of radicals and ions have been critically evaluated. Data for more than 500 bonds are represented in tabular form together with the pertinent literature references. Selected electron affinities and π-bond dissociation energies have also been incorporated. The follow-up paper will discuss some empirical general aspects of these data particularly regarding the effect of structure on the bond dissociation energies.     

Functionalization of pyridines. 3. Reactions forming a carbon-heteroatom bond with group IV, V, and VI elements

The literature from the last 15–20 years on the synthesis of heteroatomic pyridine derivatives through the formation of pyridine carbon-heteroatom bonds is reviewed. Dedicated to Professor Henk van der Plas on his 70th birthday. For No. 2, see [1]. M. V. Lomonosov Moscow State University, Moscow 119899 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 437–494, April, 1999.     

Side-chain crystallinity. V. Heats of fusion and melting temperatures on monomers whose homopolymers have long side chains

Heats of fusion and melting temperatures were obtained for selected monomeric n-alkyl acrylates, N-n-alkylacrylamides, and vinyl esters. The corresponding thermodynamic parameters for homopolymers, derived from these monomers, had been reported previously from this laboratory. The α-hexagonal crystal modification was indicated near the melting point for the higher n-alkyl acrylates, but a β form was stable at low temperatures for the entire series. The magnitude of the heats of fusion indicated β polymorphs for vinyl esters in support of x-ray diffraction analysis from the literature. Because hexagonal crystal geometry prevailed in all reported homopolymers having long side chains, greater emphasis was placed on thermodynamic data for monomers exhibiting this crystal modification. Accordingly, a convergence temperature was estimated statistically for the α-hexagonal crystal modification of these systems and appropriate literature values of the n-alkanes and ethyl esters. The convergence temperature was computed to be 135°C, uncorrected for the entropy of disorientation. The anomalously large interfacial end-packing-defect energy of the poly(n-alkyl acrylates) and the poly-N-n-alkylacrylamides was shown to be associated with a high energy barrier to molecular transport in the melt as the vitreous state was approached. In support of this conclusion, similarity of the glass and melting transition temperatures of these homopolymer homologs occurred near their critical side-chain lengths, below which the homopolymers are amorphous. A special critical requirement of nucleus length was not indicated from rough estimations of nucleation parameters for the poly(n-alkyl acrylates). These findings lent increased, but still not unqualified, support to an x-ray diffraction study from the literature. The latter had specified the inclusion of the entire side chain and the main-chain units in the crystal lattices of the higher poly(n-alkyl acrylates).     

Bond energies and formation enthalpies of mono- and polyradicals in nitroalkanes 1. Nitromethanes

The enthalpies of formation of nitromethane derivatives were obtained on the basis of experimental and literature data. The procedure for the calculation of the bond dissociation energies in nitromethanes from the atomization enthalpies and energies of nonvalent interactions of nitro groups was proposed. The calculated values were compared with the data on the thermal decomposition kinetics. The atomization enthalpies and energies of nonvalent interactions of nitro groups were also used for the calculation of the bond dissociation energies in radicals.     

Prediction of multicomponent liquid adsorption using excess quantities. II. Calculations for the liquid/solid interface

The utilization of excess quantities as the basis for a thermodynamic approach can simplify the prediction of multicomponent liquid adsorption from binary data. A new method for predicting liquid adsorption on solids is suggested, which is different from the existing equations with respect to the theoretical background and formulation. The applicability of the new model is tested with three ternary adsorption systems. The predicted surface excesses are discussed and compared with experimental ones and with those of other prediction models in the literature. The accordance between measured and predicted ternary data is convincing.     

Nucleophilic displacement reactions on fluorine. II. The role of σ- and π-bond nucleophiles

S_N2 displacement reactions on fluorine by σ- and π-bond nucleophiles are discussed and shown to constitute a general class of reaction. Mechanisms are suggested for reactions mentioned in the literature which are consistent with this generalization.     

Naturstoffchemie. 108. Mitt. Synthese des 7,7′-Oxy-dicumarins,dem möglichen Präkursor vom Lasioerin und Gnidicumarin

The synthesis of 7,7′-oxy-dicoumarin from 7-hydroxycoumarin and 7-bromocoumarin viaUllmann synthesis is described. In contrast to the literature, from the reaction ofm-bromophenol with 2-hydroxy succinic acid, 7-bromocoumarin as well as 5-bromocoumarin were obtained.     

Cross-Conjugated Cyclopentenone Prostaglandins. Recent Advances

Russian Journal of Organic Chemistry - The review covers the literature on the total synthesis of cross-conjugated cyclopentenone prostaglandins (PGs), published from 2000 until present. In view of...     

Kinetics of polyesterification. I. Dibasic acid and glycol systems

Polyesterification of diacid and diol in the absence of foreign acid is carried out under constant reaction temperatures from 140 to 180°C (rather than under constant oil bath temperature as is usually done) and molar ratios r of diol to diacid from 1 to 3.55. The experimental data obtained cannot fit conventional rate equations as they appear in the literature. Based on ion pair formation and considering additional proton transfer from acid to alcohol, we propose a reaction mechanism and rate equations. The rate equation is found to fit our experimental data very well except for r = 1. At r = 1, the kinetic plot shows two straight lines rather than one as predicted. This is attributed to unremoved water due to the higher molecular weight (and therefore higher viscosity) at r = 1 which causes a reverse reaction and slower apparent reaction rate.     

Furyl(aryl)methanes and their analogs. (Review)

The literature data on furyl(aryl)methanes are systematized and analyzed for the first time. Results obtained by the authors on the synthesis, reactions, and application of these compounds are reviewed.Kuban State Technological University, Krasnodar 350072, Russia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–901, July, 1999.     

Thermodynamics of electrolyte mixtures. Enthalpy and the effect of temperature on the activity coefficient

The temperature dependence of the parameters for symmetrical mixing of ions of the same sign in the virial-coefficient (Pitzer) system are evaluated from literature data on heats of mixing in the presence of a common ion for 20 systems. The higher-order limiting law for symmetrical mixing is used in the form of an expression for the ionic strength dependence of the binary mixing parameter. Heats of mixing of the MX-NYtype (without common ion) are calculated for eight systems from these parameters and found to be in excellent agreement with experimental values. Since pure-electrolyte parameters are required for the non-common-ion calculations, these are calculated as needed from recently published data.