Technology of the production of pectin substances from the fruit ofSorbus aucuparia

The optimum conditions for the isolation of pectin substances from a pulp of the European mountain ash freed from lipophilic substances have been studied, and the characteristics of the substances are given.Academician I. P. Pavlov Ryazan' Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 777–780, November–December, 1979.     

Hydrophilic interaction liquid chromatography method for measuring the composition of aquatic humic substances

A hydrophilic interaction liquid chromatography (HILIC) method was developed to measure the composition of humic substances from river, reservoir, and treated wastewater based on their physicochemical properties. The current method fractionates the humic substances into four well-defined groups based on parallel analyses with a neutral and a cationic HILIC column, using mobile phases of varied compositions and pH. The results indicate that: (i) the proportion of carboxylic acids in the humic substances from terrestrial origins is less than half of that from treated wastewater (Jeddah, KSA), (ii) a higher content of basic compounds was observed in the humic substances from treated wastewater and Ribou Reservoir (Cholet, France) than in the sample from Loire River (France), (iii) a higher percentage of hydrophobic macromolecules were found in the humic substances from Loire River than in the other samples, and (iv) humic substances of treated wastewater contained less ionic neutral compounds (i.e., pK_a 5–9) than the waters from terrestrial origins. The physicochemical property disparity amongst the compounds in each humic substances sample was also evaluated. The humic substances from the lightly humic Loire river displayed the highest disparity, whereas the highly humic Suwannee river (Georgia, USA) showed the most homogeneous humic substances.     

Composition of the resinous substances of conifer needles. I. Group composition of the resinous substances of the needles of the pinePinus silvestris

A system of solvents has been selected for the successive extraction of pine needles (benzene, isopropanol, and isopropanol + chloroform). Extraction was carried out by the steeping method at room temperature, and the yield of resinous substances was 19.4%. The extractive substances isolated consisted of neutral compounds, glycolipids, and phospholipids. The group compositions of the neutral substances have been determined by column chromatography. The predominating components in them are hydrocarbons (15.9%), diglycerides (10.7%), and waxy substances (27.6%).Siberian Technological Institute, Krasnoyarsk. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 396–398, May–June, 1979.     

Modern state of the chemical study of species of the genusHypericum

This review gives complete information on the chemical study of 66 species of the genusHypericum L. In individual sections the study of various groups of substances is discussed in a historical framework. The compounds isolated are given — hypericins, flavanols and tanning substances, flavones, flavonols, xanthones, coumarins, phenolcarboxylic acids, antibiotic substances, essential-oil compositions, nonvolatile saturated hydrocarbons, and other compounds. The value of these groups of substances in the connection with the pharmacological action and the therapeutic use ofHypericum species is shown. The structural formulas of 85 isolated compounds and their distribution in the species studied are given. The chemosystematic value of individual substances for the genusHypericum and the family Guttiferae is discussed.Pharmaceutical Faculty, Sofia Medical Scademy. Leningrad Institute of Pharmaceutical Chemistry. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 185–203, March–April, 1987.     

Terpenoids of the needles of Picea abies

The composition of the terpenoids of the neutral petroleum-ether-soluble substances from an isopropanol extract of the needles of the Norway spruce has been studied. The main components of the extractive substances are polyprenol acetates, alcohols with the labdane type of structure, and epimanool and epitorulosol. It has been shown that the terpenoids from the needles differ in composition from the extractive substances of the trunk part of the tree and those from the oleoresins of the sprucesPicea abies, P. ajanensis, andP. obovata.S. M. Kirov Leningrad Academy of Wood Technology. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 168–176, March–April, 1986.     

Humic substances in surface waters of the Ukraine

The results of studies of humic substances in water bodies of different types (lakes, rivers, and reservoirs) are given. It is shown that concentration of these natural organic compounds varies in a wide range of values (from 1.2 to 126.5 mg L^?1) due to different sources of their formation. The highest concentrations of humic substances are characteristic for rivers of the Pripyat’ River basin flowing through the wetland. As we move from the north to the south, the content of humic substances is reduced. So, in the Kakhovka Reservoir, closing the Dnieper cascade of reservoirs, the concentration of humic substances is almost thrice as low as in the Kiev Reservoir, which is at the head of the cascade. Seasonal changes of humic substances concentration and the reasons for these changes are discussed. The prevailing fraction in the composition of humic substances is represented by fulvic acids, the content of which reaches 80.8–94.8% of the total. The results of studies of the molecular weight distribution of humic substances and the reasons for changes in the ratio of their individual fractions, depending on the detection method (spectrophotometric and fluorescence methods), are considered. The values of the number average (M _n) and weight average (M _w) molecular weight of humic substances and the degree of polydispersity are calculated. It is shown that M _w varies seasonally. In spring and summer it is lower, but significantly increased in autumn. The reason for this phenomenon is degradation of high-molecular fractions of humic substances under the influence of UV light of solar radiation and increased microbiological activity during the summer season. As a result of these processes high-molecular fractions of humic substances are transformed into fractions with lower molecular weight, which become predominant.     

Correlation Equations for Predicting the Temperature Depression in Boiling of Aqueous Solutions of Nonvolatile Substances

Three-constant correlation equations describing the boiling point of aqueous solutions of non-volatile substances and temperature depression in boiling of the solutions under normal and arbitrary pressures are considered. The three constants appearing in the correlation equations are tabulated for aqueous solutions of 19 nonvolatile substances, and formulas for determining these constants for other aqueous solutions of nonvolatile substances from experimental data are presented.     

元素化学教学中关于“无机物热稳定性”的知识建构

"无机物热稳定性"是元素化学内容教与学的难点之一。本文选取代表性实例,通过分析、比较和归纳影响无机物热稳定性的根本影响因素,对其进行结构化、本源化理解,构建认识无机物热稳定性的思维导图,建立无机物热稳定性的认识模型。以"无机物热稳定性"为知识载体,探讨知识"建构式"的学习模式在元素化学教学中的应用。     

Chromatographic study of the inclusion properties of cyclodextrins: Study of inclusion from the gaseous phase

The ability of cyclodextrins to form inclusion compounds with substances in the gaseous phase was studied chromatographically. Chromatographic measurements enabled the mechanism of the inclusion process to be clarified and have shown that other forces, mainly hydrogen bonding, play a role in the process in addition to the geometric properties of the interacting substances. These facts are expressed in terms of the changes in the chromatographic quantities and of the changes in the thermodynamic characteristics that are derived from the former quantities. The selective properties of cyclodextrins have been utilized in separations of substances that are otherwise separated with difficulty (xylenes, diethylbenzenes, trimethylbenzenes, etc.).     

有机培肥后土壤水浸提取液成分的研究

土壤浸提液经浓缩后分成元素组成不同的顶层凝结物，中层溶解物和底层沉淀物三部分。浸提液中水溶性有机物和碳酸盐的含量，施用玉米秸秆处理高于对照处理。随着浸提液浓缩的进行，有机质全部形成不溶性的复合物。溶液中的氮以复合物的形式存在，并有一部分随着浓缩的进行而进入固相中。     

Decomposition of reaction networks: the initial phase of the permanganate/oxalic acid reaction

The determination of all chemical reaction networks composed of elementary reactions for a given net chemical reaction is one of the fundamental problems in chemistry, since the decomposition elucidates the reaction mechanism. It is essential in a wide range of applications: from the derivation of rate laws in physical chemistry to the design of large-scale reactors in process engineering where presence of unexpected side products can disturb operation. As an example we consider the well-known permanganate/oxalic acid reaction. We characterize all intermediate substances that can in principle act (auto-)catalytic, list all possible additional intermediate substances that would suffice to start the reaction without assuming presence of any autocatalyst. In particular, we propose for the first time a minimal network in which the well-known autocatalyst Mn²⁺ is produced. To derive our results we present an automatic method to determine whether a net chemical reaction can be explained by some reaction network with a given list of intermediate substances, how to generate all such networks, and how to suggest more intermediate substances if no network with the initially given substances exists.     

Effect of the degradation of ion-exchange resins on the quality of high-purity water prepared by ion-exchange deionization

In the course of water deionization on ion-exchange filters of mixed action, charged with a mixture of KU-2×8 ch.s. cation exchanger and AV-17×8 ch.s. anion exchanger, which are ion-exchange resins of nuclear class, the water being treated is contaminated with soluble organic substances originating from degradation of the resins. Their concentration can reach 20 µg L–1, gradually decreasing to 5–6 µg L–1. Procedures were suggested for determining soluble organic substances washed out from the ion-exchange filters, including gravimetric determination of their sum in aqueous extracts from the organic ion exchangers, spectrophotometric determination in water being purified on the ion exchangers, and preconcentration of electrically charged forms of soluble organic substances by electroosmosis.     

Structure of the products of acid hydrolysis of panaxoside A

Conclusions The substances obtained in the acid hydrolysis of panaxosides A, B, and C have been isolated and characterized. The structures of these substances have been established from a combination of chemical data and the results of NMR spectroscopy.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 6, pp. 352–355, 1968     

Pectin substances of the mulberry

Several variants of the isolation of pectin substances from mulberry boughs are considered.     

On the value of recent microscopic methods of identification used for organic substances

The value of recent methods of identification of organic substances by means of the micro melting point apparatus is investigated, using 3 groups of closely related substances (benzoic acid derivatives, barbituric acid derivatives, and sulphonamids).The experiments show that a combination of the melting point determination with an observation of sublimation and conversion during heating and, moreover, with the observation of the conversion of crystallised melting drops etc. very markedly increases the value of the determination.The preparation of derivatives from quantities below l mg can be performed more rapidly and more simply than the preparation of larger amounts. The melting point determination of the derivatives is of the greatest value for the identification of the respective substances.On the other hand, the melting point determination on eutectic mixtures of the substance in question with a test substance is found to be of much lower value as a method of identification, if there is a possibility for the occurrence of a number of closely related substances having the same melting point ; such substances often have the same eutectic melting point with the same test substance.The determination of the index of refraction of molten substances (i.e., the determination of the temperature interval within which the molten mass has the same index of refraction as a glass powder of a known index of refraction) is an excellent method of identification, since the scattering of the temperature intervals found for related substances is of the same magnitude, and for not related substances is considerably higher, than the scattering of their melting points.     

The detection of drugs of abuse in fingerprints using Raman spectroscopy I: latent fingerprints

This paper describes the application of Raman spectroscopy to the detection of exogenous substances in latent fingerprints. The scenario considered was that of an individual handling a substance and subsequently depositing a contaminated fingerprint. Five drugs of abuse (codeine phosphate, cocaine hydrochloride, amphetamine sulphate, barbital and nitrazepam) and five non-controlled substances of similar appearance, which may be used in the adulteration of drugs of abuse (caffeine, aspirin, paracetamol, starch and talc), were studied in both sweat-rich and sebum-rich latent fingerprints. The substances studied could be clearly distinguished using their Raman spectra and were all successfully detected in latent fingerprints. Photobleaching was necessary to reduce the fluorescence background in the spectra of some substances. Raman spectra obtained from the substances in sweat-rich latent fingerprints were of a similar quality to spectra that obtained from the substances under normal sampling conditions. Interfering Raman bands arising from latent fingerprint material were present in the spectra obtained from the substances in sebum-rich fingerprints. These bands did not prevent identification of the substances and could be successfully removed by spectral subtraction. The most difficult aspect of the detection of these substances in latent fingerprints was visually locating the substance in the fingerprint in order to obtain a Raman spectrum.     

The Influence of the Specific Surface Area of Adsorbent upon the Optimization of the Process of Adsorption Thin-Layer Chromatography

Abstract

An important aspect of the influence of specific surface area of adsorbent on R_M values of substances obtained in the process of adsorption thin-layer chromatography has been presented in the paper. The experiments have been conducted with four adsorbents, each having different specific surface area, that is, from 50 to 500 m²/g and with the use of mixed binary solvent mobile phases of benzene-aliphatic alcohol type. It has been proved that R_M values of investigated substances of group B change regulary according to the specific surface area of adsorbent for individual concentrations of mobile phase. The relationship may be described by means of square trinominal. The parameters of trinominal may be tabulated and the differentiation of the parameters for particular substances is observable at the same time. The relationship in question may be utilized to calculate R_M, values of studied substances on any adsorbent with known specific surface area.     

On the interrelation between the methodologies of chemistry and physics

Aspects of the methodology and language of chemistry and physics are discussed. Chemistry defines the chemical properties of any substance from the results of its interaction with other substances using the logic of relations. Therefore, describing the properties of substances means using sets of different ideas, including ones that are opposite in meaning. Consequently, depending on the nature of reagents with respect to which properties are established, substances show chemical dualism. This dualism was established in chemistry long before the discovery of wave–particle dualism, to understand which N. Bohr proposed the complementarity principle in 1927. The methodology of natural sciences corresponds to the principle of complementarity and the need to use it to understand the world and record the results in the linguistic reality of several languages.     

A comparison of various pyrolysis experiments for the analysis of reference humic substances

The interpretation of the results of pyrolysis studies of humic substances is fraught with difficulties if only a single analytical technique is employed for substructure analyses. In this paper we have carried out investigations into humic substances utilising the additional information from the combination of gas chromatography/infrared spectroscopy and gas chromatography/mass spectrometry detection following Curie-point pyrolysis at five different temperatures. The results were compared to those obtained from conventional flash pyrolysis. The aim was to ensure the validation of the results of the compounds identified by at least one other spectroscopic technique. Some 30 substances have been positively identified by infrared spectroscopy, although their appearance is dependent on pyrolysis method and temperature. Most assignments were validated by mass spectrometry or the substance class confirmed.     

Nucleation-fluctuation approach to determining the temperature dependence of the surface tension of metals

An analysis of nucleation processes that occur during a vapor-liquid phase transition and temperature fluctuations that take place in clusters of stable phases is employed to derive a semiempirical relation between the capillary and thermophysical characteristics of substances. The relation enables one to calculate the surface tension of elementary substances based on their thermophysical characteristics in a wide temperature range from melting to boiling points. The surface tension of metals is calculated within this temperature range. In most cases, the calculated results agree with available experimental data.