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The first homometal dicubane nickel(II) complex based on unsymmetrically substituted 1,3-diketone (1,1,1-trifluoro-4-(2-methoxyphenyl)butan-2,4-dione) was synthesized and studied by X-ray diffraction using synchrotron radiation (CCDC no. 861889). In the crystal of the complex, nickel atoms are joined into tetrahedra sharing a common vertex with Ni...Ni distances of 3.026–3.127 Å; the geometry is completed to a distorted dicubane by μ3-bridging oxygen atoms of the hydroxyl groups. The coordination environment of each metal center is a distorted octahedron, the ligand is deprotonated and performs a bidentate function, forming six-membered chelate rings. [ABSTRACT FROM AUTHOR]

Biparatopic antibodies (bpAbs) are engineered antibodies that bind to multiple different epitopes within the same antigens. bpAbs comprise diverse formats, including fragment‐based formats, and choosing the appropriate molecular format for a desired function against a target molecule is a challenging task. Moreover, optimizing the design of constructs requires selecting appropriate antibody modalities and adjusting linker length for individual bpAbs. Therefore, it is crucial to understand the characteristics of bpAbs at the molecular level. In this study, we first obtained single‐chain variable fragments and camelid heavy‐chain variable domains targeting distinct epitopes of the metal binding protein MtsA and then developed a novel format single‐chain bpAb connecting these fragment antibodies with various linkers. The physicochemical properties, binding activities, complex formation states with antigen, and functions of the bpAb were analyzed using multiple approaches. Notably, we found that the assembly state of the complexes was controlled by a linker and that longer linkers tended to form more compact complexes. These observations provide detailed molecular information that should be considered in the design of bpAbs. [ABSTRACT FROM AUTHOR]

The reaction of Cu(OAc)2 with dimethylglyoxime (H2dmg) yields the mononuclear complex [Cu(Hdmg)2] (1), whereas the reaction of Cu(ClO4)2 ⋅ 6H2O with H2dmg yields a dinuclear complex [Cu2(H2dmg)(Hdmg)(dmg)]ClO4 (2 a). Systematic studies of the stoichiometric ratios of the reactants, the nature of the anion as well as pH value show that the pH value of the reaction solution/anion governs the nuclearity. I.e., basic anions and/or addition of a base yield 1. Once the product has formed in solution, it remains stable despite further changes of the pH value or addition of excess H2dmg. A conversion of one species into the other can only be achieved by simultaneous change of pH and addition of H2dmg. Accordingly, among sole addition of a base, 2 a isomerizes but does not change its nuclearity. In contrast, if NaOtBu and H2dmg are added, 2 a converts into 1. The same happens if the slightly basic salt Na2dmg is added to a solution of 2 a. Furthermore, the formation of 2 a can be exploited for the preparation of [Cu(CH3CN)4]X (X=ClO4−, BF4−, OTf−) due to a recently reported cooperativity‐driven decomposition of 2 a. [ABSTRACT FROM AUTHOR]

The reaction of Cu(OAc)2 with dimethylglyoxime (H2dmg) yields the mononuclear complex [Cu(Hdmg)2] (1), whereas the reaction of Cu(ClO4)2 ⋅ 6H2O with H2dmg yields a dinuclear complex [Cu2(H2dmg)(Hdmg)(dmg)]ClO4 (2 a). Systematic studies of the stoichiometric ratios of the reactants, the nature of the anion as well as pH value show that the pH value of the reaction solution/anion governs the nuclearity. I.e., basic anions and/or addition of a base yield 1. Once the product has formed in solution, it remains stable despite further changes of the pH value or addition of excess H2dmg. A conversion of one species into the other can only be achieved by simultaneous change of pH and addition of H2dmg. Accordingly, among sole addition of a base, 2 a isomerizes but does not change its nuclearity. In contrast, if NaOtBu and H2dmg are added, 2 a converts into 1. The same happens if the slightly basic salt Na2dmg is added to a solution of 2 a. Furthermore, the formation of 2 a can be exploited for the preparation of [Cu(CH3CN)4]X (X=ClO4−, BF4−, OTf−) due to a recently reported cooperativity‐driven decomposition of 2 a. [ABSTRACT FROM AUTHOR]

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chelators are widely used in conservation treatments to remove metal stains from marble, travertine, and limestone surfaces. In the current review the chemical aspects underlying the use of chelators for the removal of copper and iron stains from built heritage are described and clear criteria for the selection of the most efficient stain removal treatment are given. The main chelator structural features are outlined and the operating conditions for effective metal stain removal (pH, time of application, etc.) discussed, with a particular emphasis on the ability to form stable metal complexes, the high selectivity towards the metal that should be removed, and the high sustainability for the environment. Dense matrices often host chelators for higher effectiveness, and further research is required to clarify their role in the cleaning process. Then, relevant case studies of copper and iron stain removal are discussed. On these bases, the most effective chelators for copper and stain removal are indicated, providing chemists and conservation scientists with scientific support for conservation operations on stone works of art and opening the way to the synthesis of new chelators. [ABSTRACT FROM AUTHOR]

Anthocyanins are prone to degradation and color fading after sterilization. This work examined the potential of wheat protein hydrolysates (WPHs, 40 g/L) in improving the stability of purple sweet potato anthocyanins (PSPAs) under a pH of 6.8 after sterilization at 121 °C followed by storage. Results showed that WPHs increased the thermal degradation half-life of PSPAs 1.65 times after sterilization. Compared to PSPAs alone, after being stored at 37 °C and 45 °C for 7 days, the retention concentration of PSPAs with WPHs was 5.4 and 32.2 times higher, and the color change of PSPAs with WPHs decreased from 6.19 and 10.46 to 0.29 and 0.77, respectively. AFM data, fluorescence and UV spectrograms indicated the formation of complexes between PSPAs and WPHs by hydrophobic attraction confirmed by zeta-potential data. PSPAs with WPHs had stable particle size and zeta potential, which may also significantly increase the concentrations after digestion and antioxidant power of PSPAs. This work indicated that the assembled PSPAs composite structure by WPHs significantly reduced the degradation of PSPAs at a pH of 6.8 after sterilization at 121 °C followed by long-term storage. [ABSTRACT FROM AUTHOR]

The monodentate phosphoryl-containing ligand 1-Ac-2-[Ph2P(O)]-cyclohexane (L) bearing two asymmetric carbon atoms is synthesized. The study of its crystal structure shows that L is a racemic mixture of (1R,2S) and (1S,2R) stereoisomers. The complex formation of L with TiF4 in СН2Сl2 is studied by 19F{1Н} and 31Р{1Н} NMR spectroscopy. The compositions of the complexes formed in the solution are determined. Racemic and meso-diastereomers of the octahedral complex cis-TiF4L2 are formed in the solution as found by an analysis of the 19F and 31Р NMR spectra taking into account the concept of heterotropy of organic compounds. The influence of the optical configuration of stereoisomers of the monodentate ligand coexisting in the coordination sphere of the [MF4L2] octahedral tetrafluoro complexes of transition d0 metals on the chemical shifts of the fluorine atoms arranged in the trans positions relative to each other is shown. In the meso-diastereomer of cis-TiF4L2, this results in a nonequivalence of the fluorine atoms on the F–Ti–F' ordinate of the octahedron, and the spin-spin coupling constant JFF' = 286.1 Hz is observed in the 19F{1H} NMR spectrum. [ABSTRACT FROM AUTHOR]

The monodentate phosphoryl-containing ligand 1-Ac-2-[Ph2P(O)]-cyclohexane (L) bearing two asymmetric carbon atoms is synthesized. The study of its crystal structure shows that L is a racemic mixture of (1R,2S) and (1S,2R) stereoisomers. The complex formation of L with TiF4 in СН2Сl2 is studied by 19F{1Н} and 31Р{1Н} NMR spectroscopy. The compositions of the complexes formed in the solution are determined. Racemic and meso-diastereomers of the octahedral complex cis-TiF4L2 are formed in the solution as found by an analysis of the 19F and 31Р NMR spectra taking into account the concept of heterotropy of organic compounds. The influence of the optical configuration of stereoisomers of the monodentate ligand coexisting in the coordination sphere of the [MF4L2] octahedral tetrafluoro complexes of transition d0 metals on the chemical shifts of the fluorine atoms arranged in the trans positions relative to each other is shown. In the meso-diastereomer of cis-TiF4L2, this results in a nonequivalence of the fluorine atoms on the F–Ti–F' ordinate of the octahedron, and the spin-spin coupling constant JFF' = 286.1 Hz is observed in the 19F{1H} NMR spectrum. [ABSTRACT FROM AUTHOR]

A preparative approach to thiazole-containing chromone derivatives has been developed by modifying the corresponding aldehydes with their further transformation into propenone derivatives, and finally introducing them into the Algar-Flynn-Oyamada reaction. Several methods for obtaining propenones have been analyzed, and the most effective and practically convenient one has been found. The thiazole-containing analogs of chromones obtained have a great potential as probes for a wide range of studies.

Aim. The goal of the study is to demonstrate the binding sites for curcumin on the protein carriers - bovine serum albumin and diphtheria toxoid CRM197. BSA was chosen as a potential non-specific protein carrier because of its widely used in medicine as a drug carrier. Methods. In the investigation, both spectrophotometric and molecular docking methods were used. Results. Two stable binding sites were demonstrated for BSA to bind curcumin. CRM197 was taken as a well-studied carrier protein with its own antitumor activity and has been investigated as a specific carrier with a high affinity for cancer cells with overexpression of epidermal growth factor receptor. Our results showed one possible curcumin binding site, making CRM197 an ideal specific curcumin delivery platform that provides at least an additive effect in anticancer therapies. Conclusions. In conclusion, both studied proteins form stable complexes with curcumin that can lay in base of the commercial drug application.

BACKGROUND: Myoglobin (MB), a pigmentation protein, can adversely affect the antibacterial activity of carvacrol (CAR) and weaken its bacteriostasis effect. This study aimed to clarify the influence of MB on the antibacterial activity of CAR and ascertain the mechanism involved in the observed influence, especially the interaction between the two compounds. RESULTS: Microbiological analysis indicated that the presence of MB significantly suppressed the antibacterial activity of CAR against Listeria monocytogenes. Ultraviolet–visible spectrometry and fluorescence spectroscopic analysis confirmed the interaction between CAR and MB. The stoichiometric number was determined as ~0.7 via double logarithmic Stern–Volmer equation analysis, while thermodynamic analysis showed that the conjugation of the two compounds occurred as an exothermal reaction (ΔH° = −32.3 ± 11.4 kJ mol−1 and ΔS° = −75 J mol−1 K−1). Circular dichroism, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy showed hydrogen bonding in the carvacrol–myoglobin complex (CAR‐MB). Molecular docking analysis confirmed that amino acid residues, including GLY80 and HIS82, were most likely to form hydrogen bonds with CAR, while hydrogen bonds represented the main driving force for CAR‐MB formation. CONCLUSION: CAR antibacterial activity was significantly inhibited by the presence of MB in the environment due to the notable reduction in the effective concentration of CAR caused by CAR‐MB formation. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Shale gas survey wells are usually difficult to drill because of complex geological conditions. On the basis of shale gas survey and wellbore stability analysis of Chuanmudi 2 well, the organic silicon polymer drilling fluid system was selected, and through orthogonal test, the optimum dosage of main treatment agents, such as organosilicon modified polymer, multi-grade ultra-fine calcium carbonate, emulsified paraffin and silicon fluoropolymer, was determined, and the basic formula was formed. The system shows good drilling chips contamination resistance, calcium invasion resistance, etc. in the laboratory test evaluation. Inhibitory and plugging properties. Field application shows that after using organosilicon polymer drilling fluid system, complex conditions in well Chuanmudi 2 have been significantly improved, well safety has been effectively guaranteed, and well has been successfully drilled to the designed well depth, realizing geological objectives, and drilling efficiency has been greatly improved compared with the same type of drilling in the same area. The research results can provide reference for selection and application of drilling fluids in complex formation of shale gas survey wells. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sapogenins are the non-sugar parts of saponins (aglycones), high-molecular-weight glycosides linked to one or more sugar side chains. This group of compounds presents many properties, e.g., the potent properties of reducing surface tension and foaming properties, as evidenced by the amphipathic nature of these substances. They are used in the cosmetics industry, the washing and detergent industry, and the food industry. In addition, they have many healing properties. They lower blood cholesterol but are also used to synthesize steroid drugs or hormones. As reported in the literature, saponins also show antitumor activity, leading to cell cycle inhibition and apoptosis of various neoplastic cells. In this study, the influence of two sapogenins: asiatic acid (AA) and oleanolic acid (OA), on the properties of monolayers made of phosphatidylcholine (DPPC) was investigated. The method used in these studies was the Langmuir method with Brewster angle microscopy. The interactions between the tested compounds in mixed monolayers were described. Using mathematical equations, we established that oleanolic acid and asiatic acid formed complexes with DPPC at 1:1 ratios, characterized by high stability constants. We derived the parameters characterizing the formed complexes and described the phase transitions that occur during the formation of pure and mixed monolayers. [ABSTRACT FROM AUTHOR]

3-Aminopropyltriethoxysilane and -silatrane readily enter into the Michael aza reaction with various acrylates. Depending on the ratio of the reagents, Michael mono- or diadducts, containing functional groups (triethoxysilyl, carbonyl, nitrile, amino, etc.), are formed. These compounds have been characterized by IR and NMR spectroscopy, mass spectrometry, elemental and X-ray diffraction analyses. The siloxanes obtained from corresponding trialkoxysilanes form carbonyl and nitrile complexes with Ag, Cu, and Ni salts and comprise chemically and thermally stable promising sorbents (enterosorbents) of noble and heavy toxic metal ions. In silico calculations (Protos-II, PASS and Swiss ADMET programs) show that the synthesized silatranes are non-toxic and bioavailable compounds with a pronounced antitumor effect. The effect of silatranes on the growth of pathogenic bacteria (listeria, staphylococci, and plague bacilli) has been studied in vitro. It has been found that these silatranes in microconcentrations exhibit a significant stimulating effect and can be used as growth stimulators of bacterial biomass for rapid diagnosis of diseases caused by these and other pathogens. [ABSTRACT FROM AUTHOR]

Currently, information processing of tunnel engineering has mainly adopted conventional mathematical statistics-based methods. Moreover, some nonlinear processing methods are implemented to derive more insights, even though the degree of research is not deep enough. In the research, the rock mechanics test is carried out by drilling a method and taking samples in situ according to the construction technology of tunnels in complex geological conditions and implementing computer information-based methods. Also, rock mechanics tests are carried out in the excavation test area of the flat tunnel. Based on the tests using physical properties, such as deformation, tensile, uniaxial compression, triaxial compression, and longitudinal wave velocity, the physical and mechanical characteristics of the surrounding rock in the tunnel area are comprehensively evaluated, and the stability of the tunnel rock mass is assessed to devise convenient conditions for the subsequent research of the complex geological tunnels based on green excavation. The particle density of sandy mudstone, the bulk density, the porosity, and the natural water content are represented by 2.67 ± 0.61 g/cm3, 2.56 ± 1.42 g/cm3, 7.45%, and 2.86%, respectively, in terms of physical characteristics. These indicate that the sandy mudstone structure is relatively loose, with relatively large pores, micro-fractures, and a high degree of natural water content. The representative deformation test curve of the rock block shows that the ratio of deformation modulus to the compressive strength of the rock block is 650 on average, and Poisson’s ratio ranges from 0.21 to 0.38. These show that sandy mudstone has deformation properties after compression. The tensile strength of sandy mudstone, the shear strength, and c are represented by 1.25 ± 0.23 MPa, f = 1.32, and = 2.35 MPa, respectively. The stated test results can provide a scientific basis for selecting engineering design and its construction parameters in similar areas. In addition, the measurement results show that the surrounding rock will gradually increase, and the tunnel space will gradually become shorter with the increase of buried depth when the gravity stress field occurs. The linear elastic displacement of soft rock is smaller than that of elastic–plastic analysis, and the deeper the tunnel is buried, the larger the displacement difference would be. Therefore, establishing a stable and orderly monitoring and detection system could fully understand the intrinsic law between surrounding rock stress release and surrounding rock pressure and obtain accurate monitoring and measured data to evaluate the grading management standard of a tunnel at the ultimate displacement. In a word, this research provides a feasible idea to study the decision process of green excavation and deformation control technology of tunnels in complex strata.

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations.

The object of research is the technology of fish products for HELTHY-CAFE with regulated histamine content for the development of health food diets for the population. One of the most problematic places in the technology of food products from raw materials of aquatic origin is microbiological spoilage and, as a result, the formation and accumulation of HisA, which in a certain amount causes a toxic effect. In the course of the study, the methods of isomolar series, sensory analysis, and the study of quality indicators were used. The methodology chosen in the work allows to determine the optimal ratio of hydrocolloids in the system for maximum complexation with histamine in the technology of fish culinary products in gelatin fillings with a harmonious sensory profile and adjustable histamine content. The obtained results of the conducted research allow to state that the proposed method of determining the optimal ratio of sodium alginate and low-esterified pectin substances contributes to the development of a gelatinous filling for fish culinary products in order to ensure the harmonious flavor of ready-made fish dishes and contributes to the expansion of the range of fish products for HELTHY-CAFE with functional and preventive properties. This is due to the fact that taking into account the modern trends in nutrition regarding the safety, functionality, palatability, and attractiveness of fish food products made it possible, based on the method of isomolar series and sensory analysis, to scientifically substantiate the optimal ratio of plant biopolymers, to form requirements for the texture of gelatin filling in fish technology culinary products. On the basis of previous experimental studies, it was shown that the accumulation of histamine occurs more actively in sea fish, which made it possible to substantiate the choice of raw materials for the production of fish culinary products. Taking into account the main global trends in the development of aquaculture, it is proposed to use crucian carp as a raw material, as the main object of aquaculture in Ukraine. The low activity of the peptide hydrolase complex of the muscle tissue of the carp, compared to sea fish, contributes to the formation of a harmonious aromatic profile of fish culinary products, which corresponds to consumer expectations, and the use of natural hydrocolloids of vegetable origin to form a gelatinous structure provides functional properties to the food product and allows controlling the histamine content. [ABSTRACT FROM AUTHOR]

The JESS (Joint Expert Speciation System) Thermodynamic Database (v8.9) is now available as a set of freely available PDF files. This reaction database contains about 280,000 thermodynamic parameters (equilibrium constants, enthalpies, etc.) as published in the literature for over 80,000 chemical reactions. It is grounded in the tradition of the Stability Constants Special Publications (by the Chemical Society) but it has become much more extensive and it includes some quantitative indication of parameter reliability based mainly on intra- and extra-reaction consistency. [ABSTRACT FROM AUTHOR]

A preparative approach to thiazole-containing chromone derivatives has been developed by modifying the corresponding aldehydes with their further transformation into propenone derivatives, and finally introducing them into the Algar-FlynnOyamada reaction. Several methods for obtaining propenones have been analyzed, and the most effective and practically convenient one has been found. The thiazole-containing analogs of chromones obtained have a great potential as probes for a wide range of studies. [ABSTRACT FROM AUTHOR]

We investigated the complexation reaction of N-benzoyl-N'-(phenylsulfonyl)hydrazine with Cu(II) ions in an ammonia medium. The absorption spectra of the reagent and its complex compound with Cu(II) ions were recorded and analyzed. Optimal conditions for complex formation were determined, including the pH range for complexation, the optimal time for color development, and the amount of photometric reagent. Under optimal conditions, a calibration curve for the complexation of BFSH with Cu(II) ions was plotted. The Beer–Lambert–Bouguer law is valid in the range from 0.5 to 1.75 mg of Cu(II) in 25 mL of the solution. The true (19 389 cm2/mol) and apparent (4708 cm2/mol) molar absorption coefficients were calculated. Using the methods of saturation, equilibrium shift, curve intersection, isomolar series, and conductometric titration, the molar ratios in the solution of the complex compound were determined as [Cu(II)] : [BFSH] = 1 : 1 and 1 : 2. The conditional stability constant of the complex, calculated using the Babko method, is 2.45 × 1013. The convergence and accuracy of the spectrophotometric method were determined statistically. [ABSTRACT FROM AUTHOR]

The present study provides a novel, selective analysis method for the determination of low xanthate concentrations. The rising concern over the environmental effects of xanthates demands the development of analysis methods which this study answers. Complex formation in aqueous solution between xanthates and an excess of Co(II), Ni(II), Pb(II), Cd(II), Cu(II), and Zn(II) ions was utilized to selectively determine xanthates by high‐performance liquid chromatography–inductively coupled plasma tandem mass spectrometry for the first time. The complexes that were formed were extracted to ethyl acetate using liquid–liquid extraction and separated by high‐performance liquid chromatography technique before the quantitative determination of metal ions and sulfur in the xanthate complexes. Good separation and high measurement sensitivity were achieved using Cu(II) as the complex metal ion. The analysis method was optimized for the determination of sodium isopropyl xanthate and sodium isobutyl xanthate with detection limits of 24.7 and 13.3 μg/L, respectively. With a linear calibration range of 0.1–15 mg/L and a total analysis time of 4–5 min, the present method is a fast and sensitive option for selective xanthate determination. [ABSTRACT FROM AUTHOR]

G protein‐coupled receptors (GPCRs) constitute the largest family of transmembrane proteins and play a crucial role in regulating diverse cellular functions. They transmit their signaling via binding to intracellular signal transducers and effectors, such as G proteins, GPCR kinases, and β‐arrestins. To influence specific GPCR signaling behaviors, β‐arrestins recruit effectors to form larger signaling complexes. Intriguingly, they facilitate divergent functions for the binding to different receptors. Recent studies relying on advanced structural approaches, novel biosensors and interactome analyses bring us closer to understanding how this specificity is achieved. In this article, we share our hypothesis of how active GPCRs induce specific conformational rearrangements within β‐arrestins to reveal distinct binding interfaces, enabling the recruitment of a subset of effectors to foster specialized signaling complexes. Furthermore, we discuss methods of how to comprehensively assess β‐arrestin conformational states and present the current state of research regarding the functionality of these multifaceted scaffolding proteins. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Guizhou has many coal seams, thin coal seams, many gangues, and rapid lithology changes. Its complex strata characteristics increase the difficulty of fracturing CBM wells. Taking coalbed methane well in Jinjia Coal Mine as an example, we research the risk of complex formation fracturing and fracturing technology, and explore the adaptability of secondary pump-stop fracturing technology under stress disturbance. Engineering practice show that the lithology of coal measures in Jinjia Coal Mine has complex changes, and the lithology can be divided into 5 combination modes; multi-coal and multi-layered coal seams adopt methods such as “avoidance, expansion, selective injection, continuous injection, and directional perforation”, which can reduce the difficulty of fracturing construction. Multi-seam combined layer fracturing and multi-layer coal seam fracturing reform adopted the secondary stop pump fracturing technology, promoted the formation stress redistribution and fracture diversion, and improved the effect of reservoir fracturing reform; two coalbed methane wells in the study area implemented a secondary pumping-off fracturing process. The fracturing construction curve, pressure changes after pumping-off, and gas production effect all show that the fracturing process has a better effect on reservoir reconstruction.

Anthocyanins are prone to degradation and color fading after sterilization. This work examined the potential of wheat protein hydrolysates (WPHs, 40 g/L) in improving the stability of purple sweet potato anthocyanins (PSPAs) under a pH of 6.8 after sterilization at 121 °C followed by storage. Results showed that WPHs increased the thermal degradation half-life of PSPAs 1.65 times after sterilization. Compared to PSPAs alone, after being stored at 37 °C and 45 °C for 7 days, the retention concentration of PSPAs with WPHs was 5.4 and 32.2 times higher, and the color change of PSPAs with WPHs decreased from 6.19 and 10.46 to 0.29 and 0.77, respectively. AFM data, fluorescence and UV spectrograms indicated the formation of complexes between PSPAs and WPHs by hydrophobic attraction confirmed by zeta-potential data. PSPAs with WPHs had stable particle size and zeta potential, which may also significantly increase the concentrations after digestion and antioxidant power of PSPAs. This work indicated that the assembled PSPAs composite structure by WPHs significantly reduced the degradation of PSPAs at a pH of 6.8 after sterilization at 121 °C followed by long-term storage.

A new homometallic cubane-like nickel(II) complex based on N-2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid [Ni4L4(OH)4]·2H2O (I) is synthesized, and its structure is studied by X-ray diffraction (XRD) (CIF file CCDC no. 2211359). In crystals of the complex, the metallocenters are joined into tetrahedra with the Ni...Ni distances (3.144–3.201 Å) supplemented to cubanes by the μ3-bridging oxygen atoms of the hydroxy groups. The coordination environment of each metallocenter is a distorted octahedron. The ligand is deprotonated, exists in the facial conformation, and performs the tridentate function to form two six-membered conjugated chelate cycles. [ABSTRACT FROM AUTHOR]

Imidazo[1,2-a]pyridine derivatives have excellent potential for chelation with transition metal ions. Two new imidazo[1,2-a]pyridine-8-carboxylates were synthesized and characterized by 1H NMR, 13C NMR, HRMS, and single crystal-XRD techniques. Methyl carboxylate (probe 1) turns on fluorescence upon coordination with Zn2+, while sodium carboxylate (probe 2) turns off its fluorescence upon coordination with Co2+ or Cu2+ ions present in aqueous acetonitrile medium. 13C NMR study revealed that the change in metal ion specific binding was due to the involvement of carboxylate anion in complex formation with Co2+ or Cu2+ ions. The carboxylate anion at 8-position also enhanced the sensitivity of detection of probe 2 by an order of magnitude (detection limits: 3.804 × 10–7 M, probe 1/Zn2+; 0.420 × 10–7 M, probe 2/Co2+ and 0.304 × 10–7 M, probe 2/Cu2+). The detection limits of probes 1 and 2 comply well with the World Health Organization (WHO) and US Environmental Protection Agency (US-EPA) guidelines for detection of heavy metal ions present in drinking water and ground water. Both the probes form a 1:1 complex with Zn2+, Co2+ or Cu2+, and the stoichiometry was verified by Job plot and ESI-mass analysis. The sensing mechanism is explained using 13C NMR experiments, ESI-mass analytical data and theoretical DFT calculations. The suitability of probes 1 and 2 for on-site detection and quantitative determination of Zn2+, Co2+ and Cu2+ ions present in biological, environmental and industrial samples is demonstrated. In addition, both 1 and 2 are used for detection of intracellular contamination of Zn2+, Co2+ or Cu2+ ions in onion epidermal cells. [ABSTRACT FROM AUTHOR]

The effect of cyclic and acyclic nitrogen-containing organic bases on the formation of a zinc complex with tetra(4-tert-butyl-5-phenylsulfanyl)phthalocyanine in benzene has been studied. The acid-base interaction precedes the complex formation and plays a key role in it. The scheme is given for the formation of a zinc complex with tetra(4-tert-butyl-5-phenylsulfanyl)phthalocyanine in the nitrogen-containing base-benzene system. A relationship between the catalytic activity of the base and its proton-acceptor ability and structure is determined. [ABSTRACT FROM AUTHOR]

A biocompatible supramolecular system based on sodium alginate and viologen calix[4]resorcinol for encapsulation of doxorubicin hydrochloride (DOX) has been obtained. Using a set of physicochemical methods, the polymer–macrocycle ratio, at which stable nanoparticles are formed, has been found and their morphological characteristics have been determined. It has been shown that the increase in the concentration of calix[4]resorcinol leads to the increase in the size of nanoparticles, their zeta potential being changed from negative to positive values. It has been established that the optimal supramolecular system for DOX binding is a composition with a macrocycle–polymer ratio of 1 : 50, and a change in the components ratio can induce the drug release. The effect of encapsulated DOX on the physicochemical and biological properties of the supramolecular system has been shown. [ABSTRACT FROM AUTHOR]

The acid–base properties of 1,2,3-benzotriazole (Bta) at 25°C and I = 0.1 mol/L KCl are studied in an aqueous solution by the pH-metric method. It is found that in the strongly acidic region of the solution, one of the two nitrogen atoms of the pyridine type of the Bta triazole rings undergoes protonation, and at high pH values, hydrogen abstraction occurs from the NH fragment of the molecule. The obtained values of the protonization constants of 1,2,3-benzotriazole log K1 and log K2 are 8.27 and 0.65, respectively. Using the potential of a silver electrode, the equilibria of silver(I) complex formation with 1,2,3-benzotriazole are studied. The data obtained indicate that Ag+ replaces the hydrogen ions of the ligand molecule and forms AgBta and complexes with the stability constants log β1 = 8.50 (AgBta) and log β2 = 12.65 (). [ABSTRACT FROM AUTHOR]

The complex formation of sulfasalazine with native and polymeric β-cyclodextrins in buffer solutions with a physiological pH value was studied using isothermal saturation and 1H NMR methods. It was found that sulfasalazine forms two types of complexes in reactions with above cyclodextrins, but only the formation of inclusion complexes determines the observed increase in drug solubility, which is more pronounced in the presence of polymeric β-cyclodextrin. The complex formation with β-cyclodextrin and its polymeric derivative leads to a decrease in the coefficients of sulfasalazine permeability through the model membrane, which is determined by both the stability constant of the complexes and their ability to pass through the membrane. [ABSTRACT FROM AUTHOR]

The thermodynamic and structural study of the complex formation of apple pectin with structural analogs of histidine (imidazole and its methyl ester) was carried out using spectral methods. The composition, stability constants of the complexes, and standard thermodynamic characteristics (ΔG°, ΔH°, and ΔS°) of the complex formation process were determined. The dominating contribution of the imidazole fragment of the amino acid to the stability of the pectin-histidine complex is shown. The esterification of the carboxyl group of histidine and its conversion into methyl ester influence only slightly the efficiency of complex formation with pectin, leading to a slight increase in binding. [ABSTRACT FROM AUTHOR]

Mangiferin is a strong antioxidant that presents a wide range of biological activities. The aim of this study was to evaluate, for the first time, the influence of mangiferin on tyrosinase, an enzyme responsible for melanin synthesis and the unwanted browning process of food. The research included both the kinetics and molecular interactions between tyrosinase and mangiferin. The research proved that mangiferin inhibits tyrosinase activity in a dose-dependent manner with IC50 290 +/− 6.04 µM, which was found comparable with the standard kojic acid (IC50 217.45 +/− 2.54 µM). The mechanism of inhibition was described as mixed inhibition. The interaction between tyrosinase enzyme and mangiferin was confirmed with capillary electrophoresis (CE). The analysis indicated the formation of two main, and four less significant complexes. These results have also been supported by the molecular docking studies. It was indicated that mangiferin binds to tyrosinase, similarly to L-DOPA molecule, both in the active center and peripheral site. As it was presented in molecular docking studies, mangiferin and L-DOPA molecules can interact in a similar way with surrounding amino acid residues of tyrosinase. Additionally, hydroxyl groups of mangiferin may interact with amino acids on the tyrosinase external surface causing non-specific interaction. [ABSTRACT FROM AUTHOR]

Drug delivery systems such as dendrimers, liposomes, polymers or gold/silver nanoparticles could be used to advance modern medicine. One significant pharmacological problem is crossing biological barriers by commonly used drugs, e.g., in the treatment of neurodegenerative diseases, which have a problem of the blood-brain barrier (BBB) restricting drug delivery. Numerous studies have been conducted to find appropriate drug carriers that are safe, biocompatible and efficient. In this work, we evaluate pegylated gold nanoparticles AuNP14a and AuNP14b after their conjugation with therapeutic siRNA directed against APOE4. This genetic risk factor remains the strongest predictor for late-onset Alzheimer's disease. The study aimed to assess the biophysical properties of AuNPs/siAPOE complexes and to check their biological safety on healthy cells using human brain endothelial cells (HBEC-5i). Techniques such as fluorescence polarization, circular dichroism, dynamic light scattering, ζ-potential measurements and gel retardation assay showed that AuNPs form stable complexes with siRNA. Subsequently, cytotoxicity assays proved the biological safety of formed conjugates. Obtained results enabled us to find effective concentrations of AuNPs when complexes are formed and non-toxic for healthy cells. One of the studied nanoparticles, AuNP14b complexed with siRNA, displayed lower cytotoxicity (MTT assay, cells viability −74.8 ± 3.1%) than free nanoparticles (44.7 ± 3.6%). This may be promising for further investigations in nucleic acid delivery and could have practical use in treating neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The photophysical processes and photochemical reactions of a 15-crown-5-containing pyridine-based styryl dye and its complexes with potassium, barium, lead, and calcium perchlorates in MeCN were studied by absorption, luminescence, and laser kinetic spectroscopy. The processes of trans—cis-photoisomerization, intersystem crossing to the triplet state, and charge transfer giving the TICT state were found. Quantum chemical calculations for the structures of the dye and its complexes with metal cations were performed. It was concluded that the trans—cis-photoisomerization could proceed through the triplet state with the intermediate formation of a biradical. According to the calculations, the dye complexes with metal cations have 1:1 stoichiometry. In the case of barium cation, the possibility of formation of a 2:1 sandwich complex was also confirmed. [ABSTRACT FROM AUTHOR]

The exposure of humans to Cd exerts adverse human health effects at low chronic exposure doses, but the underlying biomolecular mechanisms are incompletely understood. To gain insight into the toxicologically relevant chemistry of Cd2+ in the bloodstream, we employed an anion-exchange HPLC coupled to a flame atomic absorption spectrometer (FAAS) using a mobile phase of 100 mM NaCl with 5 mM Tris-buffer (pH 7.4) to resemble protein-free blood plasma. The injection of Cd2+ onto this HPLC-FAAS system was associated with the elution of a Cd peak that corresponded to [CdCl3]−/[CdCl4]2− complexes. The addition of 0.1–10 mM L-cysteine (Cys) to the mobile phase significantly affected the retention behavior of Cd2+, which was rationalized by the on-column formation of mixed CdCysxCly complexes. From a toxicological point of view, the results obtained with 0.1 and 0.2 mM Cys were the most relevant because they resembled plasma concentrations. The corresponding Cd-containing (~30 μM) fractions were analyzed by X-ray absorption spectroscopy and revealed an increased sulfur coordination to Cd2+ when the Cys concentration was increased from 0.1 to 0.2 mM. The putative formation of these toxicologically relevant Cd species in blood plasma was implicated in the Cd uptake into target organs and underscores the notion that a better understanding of the metabolism of Cd in the bloodstream is critical to causally link human exposure with organ-based toxicological effects. [ABSTRACT FROM AUTHOR]

Polyphenols (PP) are linked to health benefits (e.g., prevention of cancer, cardiovascular disease and obesity), which are mainly attributed to their antioxidant activity. During digestion, PP are oxidised to a significant degree reducing their bio-functionality. In recent years, the potential of various milk protein systems, including β-casein micelles, β-lactoglobulin aggregates, blood serum albumin aggregates, native casein micelles and re-assembled casein micelles, to bind and protect PP have been investigated. These studies have yet to be systematically reviewed. The functional properties of the milk protein-PP systems depend on the type and concentration of both PP and protein, as well as the structure of the resultant complexes, with environmental and processing factors also having an influence. Milk protein systems protect PP from degradation during digestion, resulting in a higher bioaccessibility and bioavailability, which improve the functional properties of PP upon consumption. This review compares different milk protein systems in terms of physicochemical properties, PP binding performance and ability to enhance the bio-functional properties of PP. The goal is to provide a comprehensive overview on the structural, binding, and functional properties of milk protein-polyphenol systems. It is concluded that milk protein complexes function effectively as delivery systems for PP, protecting PP from oxidation during digestion. [ABSTRACT FROM AUTHOR]

The wellbore instability caused by complex strata is a common problem in drilling engineering, which not only causes economic losses, but also reduces the field drilling efficiency. This paper has taken Block A of Junggar Basin as an example to explore the causes of wellbore instability in complex strata and establish corresponding solutions. Studying the core samples in this area and analyzing the logging data, it is concluded that the micro-fractures developed in the rock layer of the block provide natural channels for the entry of filtrate. At the same time, the water-sensitive clay minerals in the formation have hydration after encountering the filtrate. By optimizing the composition, the corresponding nano-strong inhibition and strong plugging potassium amine polysulfonate drilling fluid system (NPAP-2) was established. The overall use of asphalt anti-sloughing agent, nano-and micro-scale cracks (gaps) for physical plugging, wetting inversion control surface water absorption, chemical inhibition of internal hydration. The performance test shows that the HTHP water loss of the drilling fluid system is less than 10 mL, the recovery rate of rock sample is more than 86%, the viscosity is reasonable, the expansion rate is more than 89%, and the filtration loss is reduced from 8.0 to 5.0 mL. The results show that the NPAP-2 can reduce the liquid activity to enhance the inhibition, effectively improve the settlement stability of drilling fluid, reduce the filtration and ensure the wellbore stability. [ABSTRACT FROM AUTHOR]

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Experimental data available in the literature on the solubility of Cu (met.) and Cu2O (cuprite) in water under hydrothermal conditions have been processed. Key experiments on the solubility of cuprite were carried out at 300°C and the saturated vapor pressure of H2O vs. pH of the solution. As a result, a set of values of thermodynamic properties for 25°C, 1 bar and the parameters of the Helgeson–Kirkham–Flowers and Akinfiev–Diamond equations of state for Cu(I) hydroxocomplexes were obtained, which make it possible to describe their behavior in a wide range of temperatures (0–600°C), pressures (1–3000 bar), and densities of aqueous fluid (0.01–1 g/cm3). As has been shown by thermodynamic modeling, Cu+ ions are prevalent in the acidic and weakly alkaline regions of the aqueous solvent over the entire temperature and pressure range studied. The effect of the neutral CuOH hydroxocomplex begins to show up in the alkaline region at T > 300°C and grows with increasing temperature. The second copper hydroxocomplex shows up only in the strongly alkaline region, and the temperature has almost no effect on its behavior. [ABSTRACT FROM AUTHOR]

Taking coal-bed methane wells in Jinjia Mining Area as an example, the characteristics of coal-measure formation lithology changes and their influence on the quality control of CBM well drilling and completion are summarized, drilling construction parameters are optimized, and the drilling of coal seams is less harmful and more efficient. Engineering practice shows that the coal seams and roof and floor lithologies in the coalbed methane exploration area of Jinjia Mining Area are complex, mainly sandstone, mudstone, sandy mudstone, and argillaceous sandstone. The combined distribution of coal seams and roof and floor can be divided into 5 structural models; the coal-bearing strata of Longtan Formation in exploration area is suitable for drilling with medium-low drilling pressure of 20-30 kN, small displacement of 15-20 L/s, and medium-high speed drilling to avoid excessive drilling pressure caused by excessive well inclination; cement slurry density for cementing construction is not easy to exceed 1.85 g/cm3 to avoid the excessive density of cement slurry from invading the near-well zone and causing reservoir damage.

The values of the stability constants of the nickel(II) unprotonated and protonated mononuclear and binuclear complexes with cryptand[2.2.2] were determined using potentiometric titration at ionic strength µ→0 and temperature of 298 K. The structure and the main geometric characteristics of Ni2+ cryptates were optimized by quantum chemical calculations in vacuo. [ABSTRACT FROM AUTHOR]

By combining oppositely charged polydiallyldimethylammonium chloride (PDADMAC) and sodium polyacrylate (NaPA), interpolyelectrolyte complexes (IPECs) can be formed in aqueous solution. Such IPECs are studied for rather short NaPA and under variation of the Mw of PDADMAC. The focus is on elucidating the effect of having a hydrophobic modification of the NaPA, which is introduced by having 10 mol% of the monomeric units substituted by ones carrying a dodecyl alkyl chain. This modification renders the complexes more hydrophobic, which is seen in the fact that precipitation of the complexes occurs at a lower mixing ratio and the biphasic region is also wider. The structures of the soluble IPECs are studied by a combination of light and neutron scattering (SANS). It is observed that the complexes formed possess typical radii of gyration of ≈30–40 nm, which become somewhat smaller with increasing length of the PDADMAC chain. The SANS data can be described well with the Beaucage model for complexes, where locally small hydrophobic domains of cylindrical shape are formed, whose persistence length decreases with increasing content of NaPA in the complexes. In contrast no such structures are seen for NaPA without the hydrophobic modification. The cylindrical domains are then arranged within larger‐sized clusters of 30–40 nm, which become more compact with reduced length of the PDAMAC chains. The structure of the IPECs is largely determined by the presence of the hydrophobic modification of the NaPA and is further controlled by the length of the hydrophobic modification. Such IPECs of controlled structure, relatively small size, and containing hydrophobic domains are potentially interesting as delivery systems due to having domains of variable polarity. [ABSTRACT FROM AUTHOR]