The review discusses the advantages and limitations of chromatographic and electrophoretic approaches to the determination of neutral carbohydrates in various samples with complex matrices, the ...possibility of implementing a variety of liquid chromatography and capillary electrophoresis modes (in zone and micellar versions), and their combinations with various derivatization, detection, and sample preparation techniques. Conditions for the indirect detection of sugars upon the introduction of various absorbing additives into a mobile phase or supporting electrolyte, ligand-exchange capillary electrophoresis, and intracapillary complexation and the determination of carbohydrates by anion-exchange and hydrophilic chromatography are discussed.
Versions of the electrophoretic determination of neutral carbohydrates by a method of indirect detection using acridone acetic and folic acids as absorbing additives (
AA
) are proposed. The effects ...of the nature and concentration of AA, alkali, and various modifiers (cetyltrimethylammonium bromide,
CTAB
) and ionic liquids (1-dodecyl-3-methylimidazolium chloride and 1-hexadecyl-3-methylimidazolium chloride) on the electrophoretic parameters of the migration of analytes are studied. The lowest limits of detection for carbohydrates are achieved in a background electrolyte containing 2.5 mM acridone acetic acid, 75 mM KOH, 0.5 mM CTAB, and 5 vol % MeOH, and amount to 4−10 μg/mL with an efficiency of up to 350 thousand t.p. Under the conditions found, samples of buckwheat honey and human blood plasma are analyzed. It is found that in analyzing food products, it is preferable to use folic acid as a AA, because it provides the best selectivity for the separation of carbohydrates: for the sucralose−sucrose pair, the resolution factor is 7.6.
The conditions for the formation of physically adsorbed three-layer coatings of quartz capillary walls in capillary electrophoresis (CE) with successively deposited oppositely charged layers of ...polydiallyldimethylammonium chloride (PDADMAC) modifiers and citrate-stabilized gold nanoparticles (GNPs) are proposed. It was shown that three-layer PDADMAC–GNP–PDADMAC coatings favorably differ from monolayer coatings with PDADMAC by greater stability in a wide range of pH (2–10). The formed coatings were characterized by scanning electron microscopy, and the presence of a uniform dense layer of nanoparticles on the capillary surface was confirmed. The applicability of the modified capillaries under CE conditions was demonstrated by the separation of a mixture of 16 carboxylic acids. An increase in the separation selectivity achieved with the use of three-layer coatings based on GNPs was explained by the reversible exchange of citrate anions on the GNP surface with negatively charged analytes in the course of electrophoretic analysis.
The application of ionic liquids to chromatography and capillary electrophoresis as modifiers of background electrolytes, chiral selectors, and components of mobile, stationary, and pseudostationary ...phases in the separation of different classes of organic compounds is discussed; the effect of ionic liquids on the efficiency of separation and selectivity is considered.
One of the main limitations of capillary electrophoresis (CE) is the sorption of basic compounds on the walls of a quartz capillary. To prevent this phenomenon in CE, supporting electrolytes with ...various additives that prevent the sorption of analytes due to the formation of dynamic coatings are commonly used. Alternatively, covalent coatings, which have a number of advantages and expand the analytical capabilities of CE, are used. The main methods of the formation of coatings covalently bound to the walls of a quartz capillary are considered.
Arrestins regulate signaling and trafficking of G protein-coupled receptors by virtue of their preferential binding to the phosphorylated active form of the receptor. To identify sites in arrestin ...involved in receptor interaction, a nitroxide-containing side chain was introduced at each of 28 different positions in visual arrestin, and the dynamics of the side chain was used to monitor arrestin interaction with phosphorylated forms of its cognate receptor, rhodopsin. At physiological concentrations, visual arrestin associates with both inactive dark phosphorylated rhodopsin (P-Rh) and light-activated phosphorylated rhodopsin (P-Rh*). Residues distributed over the concave surfaces of the two arrestin domains are involved in weak interactions with both states of phosphorhodopsin, and the flexible C-terminal sequence (C-tail) of arrestin becomes dynamically disordered in both complexes. A large-scale movement of the C-tail is demonstrated by direct distance measurements using a doubly labeled arrestin with one nitroxide in the C-tail and the other in the N-domain. Despite some overlap, the molecular "footprint" of arrestin bound to P-Rh and P-Rh* is different, showing the structure of the complexes to be unique. Strong immobilizing interactions with residues in a highly flexible loop between β-strands V and VI are only observed in complex with the activated state. This result identifies this loop as a key recognition site in the arrestin-P-Rh* complex and supports the view that flexible sequences are key elements in protein-protein interactions.
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•Literature on Ag catalysts for alcohols liquid-phase oxidation is reviewed.•Improvement of performance needed for its use as alternative for Au catalysts.•Control of Ag-support ...interaction may optimize their catalytic performance.•Significative differences exist in selectivity trends of Au and Ag catalysts.•Nature of Ag active sites and effect of nano size require further research.
Selective oxidation of alcohols allow using them as a key resource for obtaining of aldehydes, ketones, esters and carboxylic acids, which are valuable intermediates and high value products for the fine chemical, pharmaceutical and agrochemical industries. The high environmental impact of current technologies is driving the research of greener processes in the liquid phase. Most of this research is devoted to study catalytic systems based on platinum group metals and gold. However, despite their high levels of activity, these catalyst systems are quite expensive and suffer of deactivation and stability problems. Silver-containing catalysts may be their excellent alternative. They are the basis for a number of important industrial oxidation processes in the gas-phase. However, research on its use for liquid-phase processes is quite limited, especially for selective oxidation of alcohols.
Therefore, this short review focuses on the systematization and analysis of the available literature data on the liquid phase oxidation of alcohols using silver-containing catalysts with the aim of identifying the problems and limitations of the state of the art and the prospects of further studies and practical implementation of such systems for the target processes.
The article presents an observation of the successful treatment of a patient with a fracture of the surgical neck of the right humerus against the background of osteoporotic lesions of the bone ...skeleton. This patient was initially underwent osteosynthesis with a titanium T-plate and screws, however, 2 weeks later, the metal structure migrated and the cancellous substance of the humerus head was severely destroyed, which made it difficult to carry out repeated resynthesis. We have proposed and tested a new method of osteosynthesis of fractures of the surgical neck of the shoulder using a titanium plate and a cerclage loop. The presented clinical observation demonstrates the feasibility of performing osteosynthesis according to our proposed method in patients with severe osteoporosis, when other methods of osteosynthesis are ineffective, and endoprosthetics of the humerus head is unavailable due to the burdened somatic status of the patient and the inaccessibility of this operation in small hospitals in the country.
An analysis of the influence of thermomechanical treatment (TMT) (rolling to a strain degree of 50%, annealing at a temperatures of 600–1200°C, 1 h) on the microstructure and phase composition of a ...VZh171 alloy in the initial state and after its bulk nitriding is performed. It is shown that nitriding leads to an increase in the thermal stability of the alloy microstructure. While a primary recrystallization and formation of finegrained structure occurs in an non-nitrided alloy quite intensively at the temperature above 1000°C, the process of collective recrystallization does not gain any significant development in the nitrided alloy even at an annealing temperature of 1200°C, and the microstructure remains ultrafine-grained (grain size 5–10 μm). The mechanical properties of the nitrided and non-nitrided alloy are investigated. It is established that nitriding has no significant effect on the alloy strength at room temperature. In the tests at 800°C, the maximum strength and the minimum plasticity are demonstrated by the nitrided alloy after rolling and subsequent annealing at 600°C. The optimum ratio of the ultimate tensile strength (480 MPa) to plasticity (elongation to fracture 23%) is observed in the nitrided alloy after TMT and annealing at 800°C.
Introduction.
Currently, most orthopedic traumatologists consider surgical treatment as the method of choice for fractures of the femoral neck. However, despite the constant modernization of the ...available methods of osteosynthesis, the proportion of unsatisfactory outcomes of surgical intervention and the occurrence of early postoperative complications remains quite high (from 28 to 45%) 1. One of the main directions for solving the problem of unsatisfactory outcomes of osteosynthesis is the improvement and strict control of measures taken in the postoperative period, including early activation of the patient. Despite the importance of the recovery period, there are still no unified standards for managing patients with hip fractures, and the available treatment protocols contain only a generalized plan for further therapeutic measures that do not take into account the individual characteristics of the patient. We have proposed a method for calculating the optimal load on the limb in the postoperative period. The purpose of this publication is to describe a clinical case of the effective application of the method for determining the optimal range of loads on a limb after surgical treatment of femoral neck fractures.
Materials and methods:
the study used materials from medical records and instrumental studies of the traumatology department of the TOGBUZ "City Clinical Hospital of Kotovsk", the results of dynamic observation for 12 months in a patient with a transcervical fracture of the femoral neck, for which the method we developed for determining the optimal range was applied. load on the limb after surgical treatment of injury.
Results:
12 months after the operation, the patient who used the method for determining the safe load range in the recovery period achieved full functional and anatomical recovery of the operated limb. Full body weight bearing was allowed from the 6th month.
Conclusion:
the method for determining the safe range of load on the limb after a femoral neck fracture has been tested in practice and led to a positive result, which may indicate its effectiveness.
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