Reuse of a purified solution of cetyltrimethylammonium bromide for the synthesis of gold nanorods

We investigate the possibility of reusing CTAB solutions for repeated synthesis of gold nanorods. Three tasks have been solved. The first task is to clean the growth solutions from gold nanorods. The second task is to develop a method using a purified cetyltrimethylammonium bromide solution for repeated synthesis of gold nanorods with the same optical properties as in the initial synthesis. The third task is to test the possibility of management of the optical properties of nanorods during repeated synthesis. The polydispersity of nanorods has been estimated by form factor using developed mathematical model.

Accumulation of heavy metals and arsenic with medicinal herbal raw material of common shovel harvested in Voronezh region

The Voronezh region is traditionally the most important area of crop production and agriculture. The purpose of the research was to study the contamination with heavy metals of medicinal plant raw materials of the Voronezh region using the example of the roots of ordinary burdock, prepared in urbo- and agro-ecosystems, which have various anthropogenic effects on themselves. The accumulation of heavy metals (lead, mercury, cadmium, nickel, copper, zinc, cobalt, chromium) and arsenic in 51 samples of raw materials was studied. By comparing the heavy metal content in the upper soil layers of the region and the content of these elements in the roots of the bladder, it can be assumed that there are significant physiological barriers to the accumulation of ecotoxicants in the roots of the bladder, which is especially noticeable for elements such as lead, mercury, arsenic, cadmium, cobalt and chromium. At the same time, this type of medicinal vegetal raw material is able to selectively concentrate some heavy metals included in the active centers of enzyme systems (copper and zinc). Thus, for an ordinary bladder under conditions of anthropogenic load, an edaphotype is formed, which is as a result of selection in conditions of anthropogenic pollution of the external environment and the manifestation of adaptation to these conditions.

Study of the diffusion process in films sodium salt of carboxymethyl cellulose – drug

The transport properties of medicinal films based on sodium salt of carboxymethylcellulose and the antibiotic amikacin sulfate have been studied in this work. It has been shown that the process of sorption of water vapor by such films and the release of a drug from them proceeds in an abnormal diffusion mode, which is explained by the slowdown of relaxation processes in glassy polymers, which include the sodium salt of carboxymethylcellulose. An increase of the amount of the introduced drug is accompanied by a regular decrease in the diffusion coefficients of both the process of sorption of water vapor and the release of amikacin from the films. It is noted that the formed films of sodium salt of carboxymethylcellulose-amikacin sulfate dissolve in water during the day and do not provide a prolonged release of the drug. To reduce the solubility of the films in water, the surface modification of the polymer film with calcium chloride has been carried out. It has been found that the modification does not lead to a change in the diffusion mode, but is accompanied by a regular change in the diffusion coefficients – the longer the formed films were kept in a calcium chloride solution, the lower the diffusion coefficients of the sorption of water vapor by medicinal films and the diffusion coefficients of the release of the drug amikacin from the film. It is argued that the surface modification of polymer films based on the sodium salt of carboxymethylcellulose is an effective way of imparting to them the effect of prolonging the release of a drug.

The Genus Alchemilla L. (Rosaceae) in the Flora of Chuvashia

In the flora of the Chuvash Republic, 40 species of the genus are revealed. 11 of these (A. altaica, А. argutiserrata, A. barbulata, A. cheirochlora, A. exilis, A. gibberulosa, A. hebescens, A. oxyodonta, A. plicata, A. sibirica, A. vorotnikovii) are registered in the Republic for the first time. Earlier, two species (A. pustynensis Czkalov and A. obtusa auct. non Buser) were noted here erroneously. Species are revealed whose richness corresponds to the level seen in neighbouring regions and approaches the maximum possible. Species richness of the botanicalgeographical areas differs crucially between forest (20–27) and other (steppe/steppefied/outwash) landscapes (2–11) species.

Influence of Amanita muscaria (class Agaricomycetes, fam. Amanitaceae) and Flammulina velutipes (class Agaricomycetes, fam. Physalacriaceae) on the growth and development of seedlings of Picea abies (class Pinophyta, fam. Pinaceae) and Abies sibirica (class Pinophyta, fam. Pinaceae)

The article presents studies of the influence of Amanita muscaria and Flammulina velutipes on the growth and development of seedlings of species of the Pinaceae family. The positive effect of mycorrhization by these fungi species on the growth and development of Picea abies and Abies sibirica was established. Thus, the presence of Flammulina velutipes and Amanita muscaria in the substrate accelerated the appearance of the first shoots by 4–8 days. Mycorrhization of Amanita muscaria influenced the morphometry of the seedlings of Picea abies and Abies sibirica. The main root length changed: in Picea abies it increased by 17.2%, in Abies sibirica it decreased by 12.9%, compared with the control group. In the presence of Amanita muscaria, the length of lateral roots increased by 51.0% in Picea abies seedlings, and by 32.4% in Abies sibirica seedlings, compared with the control group. The height of the aerial part in the presence of Flammulina velutipes increased in comparison with the control group in Picea abies seedlings by 52.2% and in Abies sibirica seedlings by 18.3%. Mycorrhization of Amanita muscaria seedlings caused an increase in the stem diameter at the root collar of Picea abies seedlings by 13.6%, and Abies sibirica seedlings by 12.1%.

Features of the species composition and structure of fish communities in small anthropogenic reservoirs with different content of dissolved mineral nitrogen

In 22 small anthropogenic reservoirs with an area of 0.4 to 62 ha located in the territory of the Udmurt Republic, individuals of different fish species were captured and water samples were taken in late spring for analysis of NO3–, NO2– and NH4+ content. In many reservoirs, concentrations of ammonium exceed the maximum permissible according to the fishing standards for water quality, and in some this is also the case with nitrites. Ponds with zooplanktophages (bleak Alburnus alburnus (L.) and belica Leucaspius delineates (Heckel)) present in fish communities were statistically significantly different in the increased content of total dissolved mineral nitrogen from reservoirs where these two fish species were not registered. In perch and roach reservoirs, the numerical proportion of river perch Perca fluviatilis was negatively and statistically significantly related to the level of their contamination with nitrogen ionic forms.

Isolation and radiochemical purification of samarium isotopes using ion exchange resins АВ 17×8 AND KU-2

The relevance of the research is caused by the need to develop a methodological base for determining 151Sm content in the soil cover of radioactively contaminated territories of Kazakhstan. The developed method for the determining of 151Sm will make it possible to assess the levels of soil contamination with this radionuclide, to determine the character of its spatial distribution, to allow estimating the internal exposure doses for the personnel and the population. The aim of the research is to carry out the isolation and radiochemical purification of samarium isotopes from acid solutions via using ion-exchange resins AV 17×8 and KU-2. Objects: salt solutions based on nitric and hydrochloric acid containing the stable isotopes of some natural, artificial β-emitters and isotopes of U and Th. The concentrations of nitric and hydrochloric acids were equal to the concentrations of the same acids used in the routine analysis of Pu and Am. Concentrations of chemical elements were determined using the Agilent 7700x quadrupole mass spectrometer and the iCAP 6300 Duo atomic emission spectrometer. The results of the experiments on the isolation and radiochemical purification of samarium isotopes from acidic solutions using anion-exchange resin AV 17×8 and cation-exchange resin KU-2 have been presented. It has been shown that the Sm-fraction can be purified from alkaline elements, Tl and U isotopes using the KU-2 cation-exchange resin. In turn, the isotopes U, Fe and Co can be removed using an anion exchange resin in 9M HCl media.

The structure of productivity elements of durum wheat varieties of Saratov selection

The objects of the study were plants of 14 varieties of durum wheat Triticum durum Desf., permitted for use at different times in the period from 1975 to 2014. An analysis of the elements of ear productivity in durum wheat plants of Saratov varieties under the conditions of 2020 was carried out. The varietal features of the development of the spike of the main shoot were revealed according to a number of characteristics: the number of spikelets in a spike, the number of grains in an ear, the weight of a grain, the number of ungrained and grained spikelets. The height of the plant and the length of the spike were measured. On the basis of the data obtained, the selection indices were calculated – the Canadian index, the Mexican index, the index of the linear density of the ear, the morphogenetic index of productivity. A cultivar with a balanced type of morphogenetic systems was revealed in terms of the elements of ear productivity – the number of spikelets, the number of caryopses and their weight – Luch 25. This cultivar is characterized by the most developed embryonic shoot among the studied cultivars, as well as the maximum length of the embryonic root system and a high growth rate root system of the seedling.

Synthesis and study of some properties of colloidal quantum dots of indium antimonide

Colloidal quantum dots of indium antimonide have been synthesized by a known technique. The shape and average diameters of quantum dots have been investigated by transmission electron microscopy using a transmission microscope. Controlling the size and shape of colloidal QDs provides information on the formation of the crystal structure of nanoparticles and their possible physical and optical properties. It has been found that InSb quantum dots are characterized by a polygonal shape. The results obtained for QDs correspond to the crystal lattice system of a semiconductor with a cubic crystal lattice structure. Elemental analysis of nanoparticles has been monitored by X-ray microanalysis. The experimental determination error was no more than one percent. The percentages of indium and antimony in QDs according to X-ray microanalysis data corresponded to the theoretical stoichiometry In: Sb = 1:1. Impurities of other elements constituted the level of trace amounts, which confirmed the chemical purity of the synthesized InSb QDs. The fluorescent properties of indium antimonide nanoparticles have been studied. It has been found that the luminescence intensity of InSb nanoparticles at room temperature is insignificant, which is in agreement with the literature data. The quantum yield does not exceed 1%, and the luminescence maximum lies in the range of 1040 nm.

Vegetation of the natural monument “Urochishche Kuzilinka” and its surroundings (Orel region)

The article describes the calciphytic steppe communities located in the territory of the natural monument “Urochische Kuzilinka” and its surroundings (Orel region). The communities were assigned to the association Onosmato simplicissimae–Salvietum nutantis Averinova ass. nov. That unit was included in the sub-union Bupleuro falcati–Gypsophilenion altissimae Averinova 2005 (union Festucion valesiacae Klika 1931, order Festucetalia valesiacae Soó 1947, class Festuco–Brometea Br.-Bl. et Tx. ex Soó 1947) on the basis of a diagnostic species analysis. The new association was characterized. Results of the ordination analysis of leading environmental factors for the described communities are provided.