complex chemical composition
Recently Published Documents


TOTAL DOCUMENTS

69
(FIVE YEARS 39)

H-INDEX

8
(FIVE YEARS 3)

2022 ◽  
Vol 12 (1) ◽  
pp. 473
Author(s):  
Daniela Gwiazdowska ◽  
Katarzyna Marchwińska ◽  
Krzysztof Juś ◽  
Pascaline Aimee Uwineza ◽  
Romuald Gwiazdowski ◽  
...  

The presence of Fusarium fungi and their toxic metabolites in agricultural crops contributes to significant quantitative and qualitative losses of crops, causing a direct threat to human and animal health and life. Modern strategies for reducing the level of fungi and mycotoxins in the food chain tend to rely on natural methods, including plant substances. Essential oils (EOs), due to their complex chemical composition, show high biological activity, including fungistatic properties, which means that they exhibit high potential as a biological plant protection factor. The aim of this study was to determine the fungistatic activity of three EOs against F. graminearum, and the reduction of mycotoxin biosynthesis in corn and wheat grain. All tested EOs effectively suppressed the growth of F. graminearum in concentrations of 5% and 10%. Cinnamon and verbena EOs also effectively reduced the ergosterol (ERG) content in both grains at the concentration of 1%, while at the 0.1% EO concentration, the reduction in the ERG amount depended on the EO type as well as on the grain. The degree of zearalenone (ZEA) reduction was consistent with the inhibition of ERG biosynthesis, while the reduction in deoxynivalenol (DON) was not consistent with this parameter.


Author(s):  
Nataliya Kalinina ◽  
Vasiliy Kalinin ◽  
Ivannа Serzhenko

Welded joints with corrosion-resistant steels and heat-resistant alloys, which require different modes of heat treatment to achieve the level of mechanical properties specified in the design documentation, are used for the manufacture of parts and components of the turbo-pumping unit (TPU) and liquid rocket engine. Heat-resistant alloys are a large group of alloys on iron, nickel and cobalt bases with the addition of chromium and other alloying elements (C, V, Mo, Nb, W, Ti, Al, B, etc.), whose main feature is to maintain high strength at high and cryogenic temperatures. Heat-resistant alloys are used in the manufacture of many parts of gas turbines in rocketry and jet aircraft, stationary gas turbines, the pumping of oil and gas, hydrogenation of fuel in metallurgical furnaces and many other installations. For the doping of nickel chromium γ-solid solution, several elements are used, which differently influence the increase of heat resistance and processability. Along with the main reinforcing elements (Ti, Al), refractory elements (W, Mo, Nb) are introduced into the alloy, which increase the thermal stability of the solid solution. Heat resistant alloys are based on cobalt. Cobalt has a positive effect on the heat-resistant properties of alloys. The introduction of chromium in cobalt increases its heat resistance and hardness. In addition to chromium, alloys containing cobalt include additives of other alloying elements that improve their various properties at high temperatures. A characteristic feature of these alloys is that they have relatively low heat resistance characteristics at moderate temperatures, which, however, change a little with the temperature up to 900 ° C and therefore become quite high compared to the characteristics of other heat-resistant alloys. A significant drawback of these alloys is their high cost due to the costly cobalt. Nickel-based heat-resistant alloys typically have a complex chemical composition. It includes 12–13 components, carefully balanced to obtain the required properties. The content of impurities such as silicon (Si), phosphorus (P), sulfur (S), oxygen (O) and nitrogen (N) is also controlled. The content of elements such as selenium (Se), tellurium (Te), lead (Pb) and bismuth (Bi) should be negligible, which is provided by the selection of charge materials with low content of these elements, because it is not possible to get rid of them during melting. These alloys typically contain 10–12 % chromium (Cr), up to 8% aluminum (Al) and titanium (Ti), 5–10 % cobalt (Co), as well as small amounts of boron (B), zirconium (Zr) and carbon (C). Molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta) and hafnium (Hf) are sometimes added. Heat-resistant alloys are used for the production of many parts of gas turbines in rocketry and jet aircrafts, stationary gas turbines, for pumping oil and gas products, for hydrogenation of fuel in metallurgical furnaces and in many other installations. Nickel-based heat-resistant alloys are also cryogenic, i.e., they are capable of operating and retaining mechanical properties at very low temperatures (–100 °C to –269 °C). Such alloys are chromium-nickel alloys having an austenitic structure. Not only do they have good mechanical properties that do not change over a large temperature range (–200 °C to 900 °C), they can also work in corrosive environments. Nickel-based heat-resistant alloys typically have a complex chemical composition. It includes 12–13 components, carefully balanced to obtain the required properties. Welded and combined workpieces are made of separate components that are interconnected by various welding methods. Welded and combined blanks greatly simplify the creation of complex configuration designs. Improper workpiece design or incorrect welding technology can cause defects (grooves, porosity, internal stresses) that are difficult to correct by machining. Given that finding replacements with multiple materials, working them out in production, and investigating interconnectivity during thermal forces in a product can take considerable time and money, it would be best to replace one alloy. Unifying the material used would allow the structure to work as a whole, which would increase the manufacturability of the products. After examining the different replacement options, inconel 718 was selected for the study. Studies of welded specimens of inconel 718 alloy-stainless steel for resistance to the ICC have shown that it is not appropriate to use  welded  inconel  718 for the impeller, it is advisable to use material that would ensure uninterrupted operation in a corrosive environment at cryogenic temperatures. Based on the working conditions of the parts, it is most expedient to make it from heat-resistant chromium-nickel alloys, namely, from float inconel 718 which meets the necessary strength characteristics. The recommended soldering mode is heating up to 950 ± 10 oC, holding for 30 minutes from the moment of loading into the oven, cooling to 3000C with the oven, further in the air, since it has less influence on the corrosion resistance of steels in stainless steel joints. Quality control of inconel 718 alloy by GOST methods similar to that used for the control of X67MBHT type alloys showed the results similar to those obtained by the ASTM and AMS control methods.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thomas S. Welles ◽  
Jeongmin Ahn

AbstractDecades of research have been dedicated to understanding the corrosion mechanisms of metal based implanted prosthetics utilized in modern surgical procedures. Focused primarily on mechanically driven wear, current fretting and crevice corrosion investigations have yet to precisely replicate the complex chemical composition of corrosion products recovered from patients’ periprosthetic tissue. This work specifically targets the creation of corrosion products at the metal on metal junction utilized in modular hip prosthetics. Moreover, this manuscript serves as an initial investigation into the potential interaction between implanted CoCrMo metal alloy and low amplitude electrical oscillation, similar in magnitude to those which may develop from ambient electromagnetic radiation. It is believed that introduction of such an electrical oscillation may be able to initiate electrochemical reactions between the metal and surrounding fluid, forming the precursor to secondary wear particles, without mechanically eroding the metal’s natural passivation layer. Here, we show that a low magnitude electrical oscillation (≤ 200 mV) in the megahertz frequency (106 Hz) range is capable of initiating corrosion on implanted CoCrMo without the addition of mechanical wear. Specifically, a 50 MHz, 200 mVpp sine wave generates corrosion products comprising of Cr, P, Ca, O, and C, which is consistent with previous literature on the analysis of failed hip prosthetics. These findings demonstrate that mechanical wear may not be required to initiate the production of chemically complex corrosion products.


2021 ◽  
Vol 31 (4) ◽  
pp. 44-51
Author(s):  
A.P. Pereverzev ◽  
O.D. Ostroumova

Any drug can potentially cause adverse drug reactions (ADRs), including serious and fatal. Some of them are caused by interactions with food, in particular, fruit and berry juices. Juices have a complex chemical composition and each of the chemicals can interact with drugs. Grapefruit juice is one of the most popular and well-studed in terms of potential drug interactions juices. Grapefruit juice is an inhibitor of CYP3A enzymes in the intestine involved in the presystemic metabolism of drug substrates. Therefore, it can increase their absorption. Apple juice at a concentration of 5% significantly reduces the activity of OATP, but not the activity of P-glycoprotein, which, for example, leads to a decrease in AUC and Cmax of fexofenadine to 30- 40% relative to the concentration of fexofenadine in patients drinking only water. Taking 200 ml of grape juice can reduce the concentration of phenacetin in blood plasma and increase the ratio of AUC of paracetamol to phenacetin due to the induction of CYP1A2 activity by grape juice flavonoids or by reducing the rate of absorption of phenacetin. To prevent ADRs, it is recommended to take drugs with water and and not consume simultaneously juices that are known to interact with drugs.


2021 ◽  
Vol 1208 (1) ◽  
pp. 012014
Author(s):  
Razija Begić

Abstract Due to their good structural properties, stainless Cr-Ni steels have a very wide application in various branches of technology. During the welding of stainless Cr-Ni steels with high-alloy coated electrodes, welding fumes of complex chemical composition are generated, which is very harmful for welders and the environment. For the purposes of this experiment, two variants of one rutile Cr-Ni commercial electrode, designated E 23 12 2 LR 12, were designed and fabricated. Higher production of welding fume particles also means greater danger to humans and the environment. In order to show the influence of the base material on the production of welding fume particles, an experiment for measuring the production of welding fume particles was performed in which two different steels were used as the base material, general structural steel S235JRG2 and stainless steel X6CrNiTi18.10.


2021 ◽  
Author(s):  
Rafika SOUAG ◽  
Nour elhayet KAMEL ◽  
Dalila Moudir ◽  
Yasmina MOUHEB ◽  
Fayrouz Aouchiche

Abstract This study focused on the effect of TiO 2 addition on the crystallines phases’ formation, structure and chemical durability of a nuclear glass ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgO-ZrO2-TiO2 . The materials with four contents of TiO2 , ranging from 4.11 to 7.11 wt.%, are synthesized by a discontinuous method,. For the whole of materials, X-ray diffraction analysis allow identifying an aluminosilicate belonging to pyroxenes silicates family as a main phase, powelite and calzirtite. Both SEM and DTAanalyses confirmed these results. The materials FTIR analysis reveals the glass ceramics complex chemical composition. MCC1 and MCC2 tests, performed on selected glass ceramic materials, indicate that the materials with 4.11 and 5.11 wt.% TiO2 are the most durable against Si, Al, Mg and Ce elements release, in MCC2 test; The results make conclusions valuable on the selection of such glass ceramics as candidate for the disposal of high-level waste.


2021 ◽  
Vol 653 ◽  
pp. L5
Author(s):  
N. T. Phuong ◽  
A. Dutrey ◽  
E. Chapillon ◽  
S. Guilloteau ◽  
J. Bary ◽  
...  

Context. Molecular line surveys are among the main tools to probe the structure and physical conditions in protoplanetary disks (PPDs), the birthplace of planets. The large radial and vertical temperature as well as density gradients in these PPDs lead to a complex chemical composition, making chemistry an important step to understand the variety of planetary systems. Aims. We aimed to study the chemical content of the protoplanetary disk surrounding GG Tau A, a well-known triple T Tauri system. Methods. We used NOEMA with the new correlator PolyFix to observe rotational lines at ∼2.6 to 4 mm from a few dozen molecules. We analysed the data with a radiative transfer code to derive molecular densities and the abundance relative to 13CO, which we compare to those of the TMC1 cloud and LkCa 15 disk. Results. We report the first detection of CCS in PPDs. We also marginally detect OCS and find 16 other molecules in the GG Tauri outer disk. Ten of them had been found previously, while seven others (13CN, N2H+, HNC, DNC, HC3N, CCS, and C34S) are new detections in this disk. Conclusions. The analysis confirms that sulphur chemistry is not yet properly understood. The D/H ratio, derived from DCO+/HCO+, DCN/HCN, and DNC/HNC ratios, points towards a low temperature chemistry. The detection of the rare species CCS confirms that GG Tau is a good laboratory to study the protoplanetary disk chemistry, thanks to its large disk size and mass.


Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1383
Author(s):  
Jovana Djokić ◽  
Dragana Radovanović ◽  
Zlatko Nikolovski ◽  
Zoran Andjić ◽  
Željko Kamberović

In order to reflect possible issues in future sole e-waste processing, an electrolyte of complex chemical composition reflecting system of sole e-waste processing was obtained by following a specially designed pyro-electrometallurgical method. The obtained non-standard electrolyte was further used for the purpose of comprehensive metal interference evaluation on the copper solvent extraction (SX) process. Optimization of the process included a variation of several process parameters, allowing determination of the effect of the most abundant and potentially the most influential impurities (Ni, Sn, Fe, and Zn) and 14 other trace elements. Moreover, comparing three commercial extractants of different active chelating groups, it was determined that branched aldoxime reagent is favorable for Cu extraction from the chemically complex system, as can be expected in future e-waste recycling. The results of this study showed that, under optimal conditions of 20 vol.% extractant concentration, feed pH 1.5, O/A ratio 3, and 10-min phase contact time, 88.1% of one stage Cu extraction was achieved. Co-extraction of the Fe, Zn, Ni, and Sn was under 8%, while Pb and trace elements were negligible. Optimal conditions (H2SO4 180 g/L, O/A = 2, and contact time 5 min) enabled 95.3% Cu stripping and under 6% of the most influential impurities. In addition, an impurity monitoring and distribution methodology enabled a better understanding and design of the process for the more efficient valorization of metals from e-waste.


Recycling ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 35
Author(s):  
Agnieszka Sobianowska-Turek ◽  
Weronika Urbańska ◽  
Anna Janicka ◽  
Maciej Zawiślak ◽  
Jędrzej Matla

The automotive industry is one of the fastest-growing sectors of the modern economy. Growing customer expectations, implementing solutions related to electromobility, and increasingly stringent legal restrictions in the field of environmental protection, determine the development and introduction of innovative technologies in the field of car production. To power the most modern vehicles that include electric and hybrid cars, packages of various types of lithium-ion cells are used, the number of which is constantly growing. After use, these batteries, due to their complex chemical composition, constitute hazardous waste that is difficult to manage and must be recycled in modern technological lines. The article presents the morphological characteristics of the currently used types of Li-ion cells, and the threats to the safety of people and the environment that may occur in the event of improper use of Li-ion batteries and accumulators have been identified and described on the basis of the Regulation of the European Parliament and Council (EC) No. 1272/2008 of 16 December 2008 and No. 1907/2006 of 18 December 2006 on the classification, labeling and packaging of substances and mixtures and the registration, evaluation, authorization and restriction of chemicals (REACH), establishing the European Chemicals Agency.


Author(s):  
M. Ceritoglu ◽  
M. Erman ◽  
F. Ceritoglu ◽  
H. Bektas

Background: The importance of organic fertilizers in agricultural production has increased due to the negative effects of intensive chemical fertilizer use on soil, the environment and human health. Vermicompost, as a rich organic fertilizer and soil amendment material, maybe a viable alternative to chemical fertilizers. While a low concentration of vermicompost has a promotive effect on growth, it may lead to inhibition of germination and seedling growth. Therefore, this study aimed to find appropriate dose ranges for vermicompost application.Methods: The study was carried out as a factorial experiment with a completely randomized design with three replications. The experiment was conducted in a growth chamber as a pot study with four doses of vermicompost (control, 10, 20 and 30%). Eight cultivars from four different species were used. The response of germination and seedling traits to increased vermicompost concentration was investigated.Result: In general, while 10% and 20% of vermicompost showed a promotive effect depending on species, higher dose inhibited the germination and dry matter accumulation. As a result, the promotive effect of low dose and inhibitory effect of higher doses are thought to be caused by the complex chemical composition of vermicompost and increasing medium pH. Therefore, the concentration of the vermicompost that will cause pH changes should be carefully considered and the pH range in which the plant species show optimum growth should be well determined.


Sign in / Sign up

Export Citation Format

Share Document