Solid-phase Synthesis Method Research Articles

Vanadium-based compounds for aqueous zinc ion batteries with excellent rate capability and cyclic stability

Zinc ion battery (ZIB) is becoming a research hotspot because of its high safety, low cost and environmental protection, and will become a promising new energy storage device. Vanadium-based compounds are widely investigated as positive materials because of their multivalency, rich crystal structure and high specific capacity. In this work, three vanadium-based compounds V2O5, V2O3 and VN samples are prepared by hydrothermal and solid-phase synthesis methods. The phase structure and purity of synthetic materials are demonstrated X-ray Diffraction (XRD). Morphology characterization shows that V2O5, V2O3 and VN samples have nanosheets, nanoflakes and nanoparticles structures, respectively. In addition, the electrochemical properties of V2O5, V2O3 and VN samples in ZIBs are systematically investigation. These three vanadium-based compounds all have great cycle stability and high-rate capabilities. This work provides guidance for the development of novel vanadium-based electrode materials and paves the way for the development of zinc ion storage.

HIGH-TEMPERATURE CERAMOVERMICULITE THERMAL INSULATION ON A WOLLASTONITE BUNDLE

Ceramovermiculite thermal insulation on a wollastonite bundle was obtained from chalk, diatomite and expanded vermiculite by the method of solid-phase synthesis of components. The influence of the granulometric composition of expanded vermiculite, as well as the composition of the charge on the phase composition, physical, mechanical and thermophysical properties of ceramic materials has been studied. The main crystalline phase of ceramic samples is biotite and wollastonite. The developed ceramovermiculite thermal insulation has an apparent density from 310 to 510 kg/m3 and can be operated at temperatures up to 1050 °C inclusive. The developed materials can be used as refractory thermal insulation of industrial furnaces, equipment, etc.

Identification, Screening and Antibacterial Mechanism Analysis of Novel Antimicrobial Peptides from Sturgeon (Acipenser ruthenus) Spermary.

Fish is an important source of antimicrobial peptides. This study aimed to identify and screen antibacterial peptides with excellent antibacterial activity derived from sturgeon spermary peptides (SSPs) and to analyze their antibacterial activity and mechanism. Liquid chromatography-mass spectrometry/mass spectrometry methods were used to analyze and identify peptide sequences, computational prediction tool and molecular docking methods were used for virtual screening of antimicrobial peptides, and finally, candidate peptides were synthesized by solid-phase synthesis method. The results demonstrate that SSPs have excellent inhibitory activity against Escherichia coli with an inhibitory rate of 76.46%. Most parts of the SSPs were derived from the sturgeon (Acipenser ruthenus) histones, and the coverage of histone H2B was the highest (45%). Two novel peptides (NDEELNKLM and RSSKRRQ) were obtained by in silico prediction tools and molecular docking, which may interact with the DNA gyrase and dihydrofolate reductase of E. coli by forming salt bridges and hydrogen bonds. Compared to the individual peptides, the antibacterial effect was significantly improved by mixing the two peptides in equal proportions. Two novel peptides change the permeability of the E. coli cell membranes and may exert antimicrobial activity by inhibiting the metabolic process of the nucleic acids.

Analysis of Phase Diagram of CaO-CoOx-ErOy and Crystal Structure of Perovskite (Ca3−xErx)Co2O6−z Solid Solution

In this work, a series of compounds in the CaO-CoOx-ErOy ternary oxide system were synthesized in air at 885 °C, using a high temperature solid-phase synthesis method. The phase boundary of each solid solution region in the CaO-CoOx-ErOy system was determined by X-ray powder diffraction techniques. The phase diagram of the CaO-CoOx-ErOy system at 885 °C includes three series of ternary oxide solid solutions: (Ca3−xErx)Co4O9−z (0 ≤ x ≤ 0.9), (Ca3−xErx)Co2O6−z (0 ≤ x ≤ 1.25), and (Er1−xCax)CoO3−z (0 ≤ x ≤ 0.33). Four three-phase regions and five solid solution tie-line regions were obtained. The structure of the perovskite solid solution (Ca3−xErx)Co2O6−z has been analyzed by Rietveld refinements. With the increase of Er content, the cell parameters of (Ca3−xErx)Co2O6−z exhibit a decreasing trend in a and b directions and an increasing trend in c direction. A brief comparison of the phase diagrams of the CaO-CoOx-ROy (R = La, Dy, and Er) systems in air at 885 °C is provided.

Anti-thermal quenching behavior of Sm3+ doped SrMoO4 phosphor for new application in temperature sensing

SrMoO4: Sm3+ orange red-emitting phosphors for novel application in temperature measurement were prepared by solid-phase synthesis method. SrMoO4: Sm3+ phosphor with scheelite structure was assigned to tetragonal system and I41/a space group. Sm3+ ions could occupy Sr2+ lattice sites of SrMoO4. SrMoO4: Sm3+ consisted of irregular microparticle with well-crystallized pomegranate seed-like morphology and Sm3+ ions can be evenly distributed in the SrMoO4 matrix. The band gap value of SrMoO4: 1.0%Sm3+ (∼4.228 eV) is less than that of SrMoO4 (∼4.267 eV), which is due to generation of defective energy levels in band gap. The appropriate quenching concentration of Sm3+ was 1.0%, the critical distance is ∼25.57 Å and θ is 7.1, close to 8, which was attributed to dipole−quadrupole interaction type of electric multipolar interaction. SrMoO4:1.0%Sm3+ had excellent thermal stability of the PL peak at 598 nm and 644 nm and anti-thermal quenching property of the PL peak at 530 nm and 563 nm. The activation energy based on the intensity of the PL peak at 598 nm is 0.318 eV. The new dual-model thermometry strategy base on exponential function and modified Boltzmann population distribution would be proposed. SrMoO4:Sm3+ phosphor had the absolute sensitivities of 0.108 K−1 based on exponential function and the relative sensitivities of 0.601% K−1 based on modified Boltzmann population distribution. The excellent anti-thermal quenching and good thermal stability of SrMoO4: Sm3+ phosphors indicate that it has a potential for applications as pc-WLEDs and optical thermometry.

Dual-emitting from Bi[formula omitted], Ln[formula omitted] (Ln [formula omitted] Eu, Sm) co-activated Ca[formula omitted]Sb[formula omitted]O[formula omitted] phosphor for optical temperature measurement

In this paper, a series of Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) fluorescent powder samples were successfully obtained, which used the traditional high-temperature solid-phase synthesis method in the preparation process. Samples of Ca2Sb2O7: Bi3+, Ln3+ (Ln = Eu, Sm) fluorescent powder samples were structurally and optically characterized​ using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), photoluminescence excitation spectroscopy and emission spectroscopy, and fluorescence decay measurements. The results show that the prepared Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) samples have an orthogonal spider web structure, which remains unchanged whether Bi3+ is single doped or Bi3+ is co-doped with Ln3+ (Ln = Eu, Sm). Under ultraviolet lamp (λex=340nm) irradiation, Bi3+ doped Ca2Sb2O7 powder shows a wide emission band centered at 435 nm, which is owing to the 3P1→1S0 transition of Bi3+ ion. Therefore, the effect of Bi3+ and Ln3+ (Ln = Eu, Sm) co-doped Ca2Sb2O7 samples on the luminescence intensity of the samples at different concentrations was studied. When the temperature was varied from 293 K to 483 K, the absolute temperature sensitivity (Sa) of doped Bi3+/Eu3+ and Bi3+/Sm3+ phosphors is 0.001K−1 (at 483 K) and 0.02K−1 (at 293 K), respectively, and the relative temperature sensitivity (Sr) is 1.03% K−1 (at 343 K) and 1.19% K−1 (at 293 K), respectively. These results demonstrate that Ca(2−x−y) Sb2O7: xBi3+, yLn3+(Ln = Eu, Sm) phosphors are prospective double emission thermal thermometers.

Characterization of manganized soluble dietary fiber complexes from tigernut meal and study of the suppressive activity of digestive enzymes in vitro.

In this study, manganized soluble dietary fiber (SDF-Mn(II)) was prepared from tigernut meal using a microwave solid-phase synthesis method with SDF. Microscopic morphological and structural analyses of SDF-Mn(II) were carried out using scanning electron microscopy, Fourier infrared spectroscopy, UV full-band scanning, X-ray diffraction, a thermal analyzer, gel permeation chromatography, and nuclear magnetic resonance, and its in vitro hypoglycemic activity was initially investigated. The results of these analyses revealed that the reaction of Mn(II) with SDF mainly involved hydroxyl and carbonyl groups, with the Nuclear magnetic resonance (NMR) analysis showing that specific covalent binding was produced and substitution was mainly carried out at the C6 position. Moreover, compared with SDF, the SDF-Mn(II) complex exhibited a porous structure, red-shifted, and color-enhancing effects on the UV characteristic peaks, significantly increased crystallinity and decreased molecular weight, and improved thermal stability; in addition, SDF-Mn(II) afforded significantly enhanced inhibition of α-amylase and α-glucosidase and possesses good in vitro digestive enzyme inhibition activity.

Porous corallite-like NiSe2/CNTs nanocomposite fabricated by a convenient one-step in-suit solid-phase synthesis method with high performance in both supercapacitor and sodium-ion battery

If the agglomeration problem can be well addressed, the solid-phase synthesis method would be evolved into an effective strategy for the preparation of transition metal-base energy storage materials with the merits of convenience, eco-friendliness, and cost-effectiveness. In this work, a convenient one-step in-suit solid-phase synthesis (ISPS) method is developed for the fabrication of a porous corallite-like NiSe2/CNTs nanocomposite. The porous 3D framework constructed by CNTs provides a high-conductivity substance for the loading of NiSe2 nanospheres to form a nanocomposite with high conductivity, loose porous morphology, and small NiSe2 size, resulting in a good performance in both supercapacitor (SC) and sodium-ion battery (SIB). A high specific capacity of 172.70 mAh g−1 is achieved at 1 A g−1 for the synthesized nanocomposite as an electrode material of SC, which value remains at 108.64 mAh g−1 at 20 A g−1. High specific energy (42.8 Wh kg−1 at 0.84 kW kg−1) and excellent cycle durability (100% capacity retention after 20,000 cycles) are exhibited by a hybrid supercapacitor device assembled with a hierarchical porous carbon. When used as the anode of SIB, the synthesized nanocomposite delivers a high reversible specific capacity of 415.8 mAh g−1 after 270 cycles at 100 mA g−1, which is retained at 330 mAh g−1 after 360 cycles at 2.0 A g−1. The outstanding performance of the synthesized nanocomposite in both SC and SIB demonstrates the great prospect of the proposed ISPS method in the synthesis of high-performance energy storage materials.

Cr and Mg codoped bismuth tantalate pyrochlores: Thermal expansion and stability, crystal structure, electrical and optical properties, NEXAFS and XPS study

A series of Bi2Cr1-xMgxTa2O9+Δ solid solutions with the pyrochlore structure was synthesized by the method of solid-phase synthesis. Structural parameters of the disordered pyrochlore were determined by the Rietveld method (space group Fd-3m:2 (No. 227), Z = 8). As the magnesium content increases, the unit cell parameter rises continuously from 10.4596 ± 0.0001 Å (x = 0.3) to 10.5463 ± 0.0001 (x = 1.0) according to the Vegard rule. The grain size varies in the range of 0.5–2 μm, regardless of the magnesium/chromium(III) ratio. Chromium ions increase the range of thermal stability of ceramics up to 1110 °C.The thermal expansion coefficient in the range of 30–1110 °C increases continuously from 4.1 to 8.6 × 10−6 °C−1 (for x = 0.5). The oxidation states of ions were determined by X-ray spectroscopy (XPS and NEXAFS). It was shown that bismuth and magnesium ions in the pyrochlore are in the Bi(+3), Mg(+2) charge states, and for chromium the states Cr(+3), Cr(+6) are most probable. Based on the presence of an energy shift in the region of Ta4f, Ta5p and Ta5d absorption edges by ΔЕ∼0.7 eV and ∼1 eV, respectively, it was concluded that the oxidation degree of the Ta(+5-δ) ion decreased. The band gap for the samples in the case of direct allowed electronic transitions is in the range of 2.14–2.29 eV. At RT and in the frequency range (102–106 Hz), the dielectric permittivity of the samples is practically constant and it decreases with increasing amount of chromium from 20 (x = 0.7) to 16 (x = 0.3) at 1 MHz.In the high-frequency region (≥105 Hz), the dielectric loss tangent for all samples is independent on frequency and takes low values of ∼0.004 (1 MHz). The activation energy of conductivity for the samples varies in the range of 1.39–1.48 eV. The ability to adsorb water was found for chromium pyrochlores.

Development of versatile solid-phase methods for syntheses of PROTACs with diverse E3 ligands

Developing highly active proteolysis-targeting chimeras (PROTACs) requires investigating a variety of ubiquitin ligase (E3 ligase) ligands and linker structures as well as their lengths. In this study, we developed a solid-phase synthesis method that affords PROTAC design diversity. We expanded the E3 ligand range to include Von Hippel-Lindau (VHL) and inhibitor of apoptosis protein (IAP) ligands because only the cereblon (CRBN) ligand thalidomide and its derivatives have been investigated for solid-phase synthesis of PROTACs. Moreover, we examined the suitability of a polyethylene glycol (PEG) rather than an alkyl linker used in our previous study for synthesizing PROTACs. Facile and rapid solid-phase synthesis methods using the above E3 ligands for developing PROTACs targeting bromodomain-containing protein 4 (BRD4) were accomplished. Western blotting analysis revealed that minor differences in the E3 ligand and linker type significantly affected the activity of the synthesized PROTACs. Our solid-phase PROTAC synthesis methods enable rapid synthesis of multiple PROTACs with various combinations of ligands for the protein-of-interest and E3 ligands and linkers that connect these ligands.

Molecular Docking, Anti-Biofilm & Antibacterial Activities and Therapeutic Index of mCM11 Peptide on Acinetobacter baumannii Strains

Despite the huge efforts of microbiologists, infectious diseases have yet remained one of the leading causes of death in humans, further highlighting the research priority for controlling opportunistic pathogens. Many researchers have used antibacterial peptides to solve the problem of antibiotic resistance. This research is thus conducted to investigate the antibacterial and anti-biofilm activity of a novel modified cecropin-melittin 11-peptide with improved therapeutic properties and lower side effects. After synthesis and purification of mCM11 (NH2-WRLFRRILRVL-NH2) by solid-phase synthesis and HPLC methods, respectively, the antibacterial and biofilm inhibitory activities were explored in vitro. TMHMM was used to confirm the reaction of mCM11 on the plasma membrane of the prokaryotic cells. The interaction between mCM11 on Acinetobacter baumannii strains was investigated by molecular docking using ClusPro2.0. Hemolysis and therapeutic indexes were also calculated to quantify the relative safety and adverse effects of mCM11. According to the results, mCM11 has a high inhibitory and lethal effect on A. baumannii strains due to its cationic properties and new specific sequence. Molecular docking revealed the release of a significant amount of energy when mCM11 binds to the surface of A. baumannii in an appropriate site. The findings indicated that mCM11 IC50 (4μg/mL) lysed 2.78% of RBCs; moreover, 8 strains of Acinetobacter baumannii showed a favorable therapeutic index. The mCM11 exhibits strong antibacterial and antibiofilm activities against A. baumannii strains, suggesting its potential therapeutic role in infections caused by these strains. Similar to its impact on A. baumannii, mCM11 could be a suitable alternative to antibiotics in combat against antibiotic-resistant bacteria in the in vivo experiments.

Enhanced triboelectric degradation of organics by regulating oxygen vacancies and constructing heterojunctions

In contrast to conventional oxidation techniques, tribocatalysis degradation of organics has gained much attention in recent years due to its mild requirement and low amount of energy needed. Therefore, we prepared Ba1.4Sr3.6NdNb7Ti3O30 (BSNNT) ferroelectric nanopowder by a solid-phase synthesis method and further investigated the effects of oxygen vacancies and heterojunctions on the tribocatalysis effect. The results showed that the introduction of oxygen vacancies not only reduced the valence electron potential required for the reaction but also greatly reduced the combination of electrons and holes. The efficiency of degradation of RhB by oxygen vacancy-rich BSNNT can reach 97 % after 2 h. Furthermore, the BSNNT-N2/CN-2 (BN2/CN-2) Z-type heterojunction achieves a tribocatalytic enhancement with 98.2 % RhB degradation in 2 h, which is attributed to the built-in electric field of ferroelectric materials and the appropriate band gap matching between g-C3N4 (CN) and BSNNT-N2 (BN2), facilitating the electron and hole transport paths between the semiconductor and ferroelectric materials. Therefore, new approaches to enhance tribocatalytic degradation of dye wastewater by increasing oxygen vacancies and constructing heterojunctions were proposed and examined based on tungsten bronze ferroelectric materials.

Preparation of an amphiphilic peptide (P13) with proton sponge effect and analysis of its antitumor activity

In order to prevent drugs from being captured and degraded by the acidic environment of organelles, such as lysosomes, after entering cells, this study designed and synthesized a novel carrier amphiphilic polypeptide (DGRHHHLLLAAAA), designated P13, for use as a tumor-targeting drug delivery vehicle. The P13 peptide was synthesized by the solid phase synthesis method, and its self-assembly behavior and drug-loading capacity in aqueous solution were studied and characterized in vitro. Doxorubicin (DOX) was loaded by dialysis method, and P13 and DOX were mixed at a mass ratio of 6:1 to form regular rounded globules. The acid–base buffering capacity of P13 was investigated determined by acid–base titration. The results revealed that P13 had excellent acid–base buffering capacity, a critical micelle concentration value of about 0.000 21 g l−1, and the particle size of P13-Dox nanospheres was 167 nm. The drug encapsulation efficiency and drug loading capacity of micelles were 20.40 ± 1.21% and 21.25 ± 2.79%, respectively. At the concentration of 50 μg ml−1 of P13-DOX , the inhibition rate was 73.35%. The results of the in vivo antitumor activity assay in mice showed that P13-DOX also exhibited excellent inhibitory effect on tumor growth, compared with the tumor weight of 1.1 g in the control group, the tumor weight in the P13-DOX-treated group was only 0.26 g. Additionally, the results of hematoxylin and eosin staining of the organs showed that P13-DOX had no damaging effect on normal tissues. The novel amphiphilic peptide P13 with proton sponge effect designed and prepared in this study is expected to be a promising tumor-targeting drug carrier with excellent application potential.

Solid Phase Synthesis of Fluorosulfate Containing Macrocycles for Chemoproteomic Workflows

AbstractMacrocyclic peptides are attractive for chemoproteomic applications due to their modular synthesis and potential for high target selectivity. We describe a solid phase synthesis method for the efficient generation of libraries of small macrocycles that contain an electrophile and alkyne handle. The modular synthesis produces libraries that can be directly screened using simple SDS‐PAGE readouts and then optimal lead molecules applied to proteomic analysis. We generated a library of 480 macrocyclic peptides containing the weakly reactive fluorosulfate (OSF) electrophile. Initial screening of a subset of the library containing each of the various diversity elements identified initial molecules of interest. The corresponding positional and confirmational isomers were then screened to select molecules that showed specific protein labeling patterns that were dependent on the probe structure. The most promising hits were applied to standard chemoproteomic workflows to identify protein targets. Our results demonstrate the feasibility of rapid, on‐resin synthesis of diverse macrocyclic electrophiles to generate new classes of covalent ligands.

Synthesis and Characterization of the Properties of (1-x)Si3N4-xAl2O3 Ceramics with Variation of the Components.

The aim of this paper is to study the effect of variation in the component ratio of (1-x)Si3N4-xAl2O3 ceramics on the phase composition, strength and thermal properties of ceramics. To obtain ceramics and their further study, the solid-phase synthesis method combined with thermal annealing of samples at a temperature of 1500 °C typical for the initialization of phase transformation processes was used. The relevance and novelty of this study lies in obtaining new data on the processes of phase transformations with a variation in the composition of ceramics, as well as determining the effect of the phase composition on the resistance of ceramics to external influences. According to X-ray phase analysis data, it was found that an increase in the Si3N4 concentration in the composition of ceramics leads to a partial displacement of the tetragonal phase of SiO2 and Al2(SiO4)O and an increase in the contribution of Si3N4. Evaluation of the optical properties of the synthesized ceramics depending on the ratio of the components showed that the formation of the Si3N4 phase leads to an increase in the band gap and the absorbing ability of the ceramics due to the formation of additional absorption bands from 3.7-3.8 eV. Analysis of the strength dependences showed that an increase in the contribution of the Si3N4 phase with subsequent displacement of the oxide phases leads to a strengthening of the ceramic by more than 15-20%. At the same time, it was found that a change in the phase ratio leads to the hardening of ceramics, as well as an increase in crack resistance.

Sustained and Targeted Delivery of Self-Assembled Doxorubicin Nonapeptides Using pH-Responsive Hydrogels for Osteosarcoma Chemotherapy

While chemotherapeutic agents have particularly potent effects in many types of cancer, their clinical applications are still far from satisfactory due to off-target drug exposure, chemotherapy resistance, and adverse effects, especially in osteosarcoma. Therefore, it is clinically promising to construct a novel tumor-targeted drug delivery system to control drug release and alleviate side effects. In this study, a pH-responsive nonapeptide hydrogel was designed and fabricated for the tumor-targeted drug delivery of doxorubicin (DOX). Using a solid-phase synthesis method, a nonapeptide named P1 peptide that is structurally akin to surfactant-like peptides (SLPs) due to its hydrophobic tail and hydrophilic head was synthesized. The physicochemical properties of the P1 hydrogel were characterized via encapsulation capacity, transmission electron microscopy (TEM), circular dichroism (CD), zeta potential, rheological analysis, and drug release studies. We also used in vitro and in vivo experiments to investigate the cytocompatibility and tumor inhibitory efficacy of the drug-loaded peptide hydrogel. The P1 peptide could self-assemble into biodegradable hydrogels under neutral conditions, and the prepared drug-loaded hydrogels exhibited good injectability and biocompatibility. The in vitro drug release studies showed that DOX-P1 hydrogels had high sensitivity to acidic conditions (pH 5.8 versus 7.4, up to 3.6-fold). Furthermore, the in vivo experiments demonstrated that the DOX-P1 hydrogel could not only amplify the therapeutic effect but also increase DOX accumulation at the tumor site. Our study proposes a promising approach to designing a pH-responsive hydrogel with controlled doxorubicin-release action based on self-assembled nonapeptides for targeted chemotherapy.

Mn-Doped Spinel for Removing Cr(VI) from Aqueous Solutions: Adsorption Characteristics and Mechanisms

In this study, the manganese (Mn) was doped in the MnFe2O4 crystal by the solid-phase synthesis method. Under the optimum conditions (pH = 3), the max removal rate and adsorption quantity of Cr(VI) on MnFe2O4 adsorbent obtain under pH = 3 were 92.54% and 5.813 mg/g, respectively. The DFT calculation results indicated that the adsorption energy (Eads) between HCrO4- and MnFe2O4 is -215.2 KJ/mol. The Cr(VI) is mainly adsorbed on the Mn atoms via chemical bonds in the form of HCrO4-. The adsorption of Mn on the MnFe2O4 surface belonged to chemisorption and conformed to the Pseudo-second-order equation. The mechanism investigation indicated that the Mn in MnFe2O4 has an excellent enhancement effect on the Cr(VI) removal process. The roles of Mn in the Cr(VI) removal process included two parts, providing adsorbing sites and being reductant. Firstly, the Cr(VI) is adsorbed onto the MnFe2O4 via chemisorption. The Mn in MnFe2O4 can form ionic bonds with the O atoms of HCrO4-/CrO42-, thus providing the firm adsorbing sites for the Cr(VI). Subsequently, the dissolved Mn(II) can reduce Cr(VI) to Cr(III). The disproportionation of oxidized Mn(III) produced Mn(II), causing Mn(II) to continue to participate in the Cr(VI) reduction. Finally, the reduced Cr(III) is deposited on the MnFe2O4 surface in the form of Cr(OH)3 colloids, which can be separated by magnetic separation.

Concentration-mediated Folding and Unfolding of Collagen Triple Helix.

Collagen has been widely utilized in tissue engineering, regenerative medicine and cosmetics. Collagen of low concentrations is frequently applied to reduce the production cost, while it may result in the loss of triple helical structure and bioactivity. CD and NMR techniques have enhanced our understanding of collagen triple helix, while they require high concentrations of collagen samples. We have systematically investigated the folding and unfolding features of collagen mimetic peptides at a broad variety of concentrations in order to decipher the role of the concentration in the triple helical stability. Peptide FAM-G(POG)10 was synthesized by the solid phase synthesis method. Fluorescence spectra of peptide FAM-G(POG)10 at different concentrations were recorded. The unfolding and folding profiles of peptide FAM-G(POG)10 with concentrations varying from 1 nM to 100 μM were examined. The effect of concentration on the folding and unfolding capability of peptide FAMG( POG)10 was investigated. Fluorescence characterization of peptide FAM-G(POG)10 under widely varying concentrations from 1 nM to 100 μM has revealed that concentration played a critical role in the stability of collagen peptides. The two-phase pattern of the concentration-dependent folding and unfolding curves has for the first time demonstrated the presence of a critical concentration for the collagen peptide to trigger the complete folding of the triple helix and to maintain the triple helix structure. It is noteworthy that the triple helix structure of collagen peptides was very stable at μM-level concentrations from both the folding and unfolding perspectives. It has significantly contributed to our understanding of collagen triple helix stability at low and ultra-low concentrations, and provided valuable and practical guidelines for the preparation of collagen-based products.

Proton Conductivity in Rare-Earth Fluorine-Containing Molybdates NaLn4Mo3O15F

The fluorine-containing fluorite-like compounds of composition NaLn4Mo3O15F (Ln = La, Pr, Nd) are produced using the method of solid-phase synthesis in air. Their thermomechanical and conducting properties, as well as hygroscopicity, are studied. It is confirmed that the synthesized specimens are isostructural to the cubic compounds Ln5Mo3O16 with the fluorite-like structure. It is shown that in the temperature range of 20–600°C, the specimens of NaLn4Mo3O15F (Ln = La, Pr, Nd) expand linearly, and their thermal expansion coefficients (13–14) × 10–6 K–1 are close to the coefficients of conventional SOFC electrolytes, for example, YSZ. Using the thermal gravimetric analysis, it is shown that the weight loss of the studied specimens in the range from 30 to 700°C is caused by their hygroscopicity. The electrophysical properties of the compounds are studied using the method of impedance spectroscopy in the humid atmosphere, and the proton component of conductivity is revealed.

Особенности структуры, микроструктуры, радиоизлучающих и радиопоглощающих свойств механоактивированной и немеханоактивированной керамики BiFeO-=SUB=-3-=/SUB=-

By the method of the two-stage solid-phase synthesis from a stoichiometric mixture of the bismuth and iron oxides, mechanically and non-mechanically activated samples of bismuth ferrite ceramics were prepared. The phase composition of the ceramic samples is predominantly BiFeO3, while Bi25FeO40 and Bi2Fe4O9 are recorded in minor amounts, the proportion of the latter decreases due to mechanical activation. Mechanical processing of the samples expands the range of linear sizes of microparticles. It has been established that mechanically activated bismuth ferrite ceramics absorb electromagnetic microwave energy up to -16 dB, while the samples of the original material absorb up to -25 dB. Both ceramic samples are capable of emitting a weak electromagnetic field, which decreases with increasing height above the sample.