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Abstract  

We discuss determination of jumps for functions with generalized bounded variation. The questions are motivated by A. Gelb and E. Tadmor [1], F. M�ricz [5] and [6] and Q. L. Shi and X. L. Shi [7]. Corollary 1 improves the results proved in B. I. Golubov [2] and G. Kvernadze [3].

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The thermal and structural properties of binary blends of Nylon-6 (N6) and a chemically related biopolymer, Bombyx mori silk fibroin (SF), are reported in this work. Homopolymers and blends, in composition ratios of N6/SF ranging from 95/05 to 70/30, were investigated by thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and wide angle X-ray scattering (WAXS). Silk fibroin typically degrades at temperatures just above 210°C, which occurs within the melting endotherm of N6. In TG studies, the measured mass remaining was slightly greater than expected, indicating the blends had improved thermal stability. No beta sheet crystals of SF were detected by FTIR analysis of the Amide I region. Strong interaction between N6 and SF chains was observed, possibly as a result of formation of hydrogen bonds between N6 and SF chains. DSC analysis showed that the addition of SF to N6 caused a decrease in the crystallization temperature, the melting temperature of the lowest melting crystals and the crystallinity of N6. Furthermore, the α-crystallographic phase dominates and the γ-crystallographic phase was not observed in N6/SF blends, in contrast to the homopolymer N6, which contains both phases. We suggest that the addition of SF might result in changes of the chain extension of N6, which lead to the appearance of α-rather than γ-phase crystals.

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Abstract  

YBaCo4O7 compound is capable to intake and release a large amount of oxygen in the temperature range of 200–400°C. In the present study, the effect of Zn, Ga and Fe substitution for Co on the oxygen adsorption/desorption properties of YBaCo4O7 were investigated by thermogravimetry (TG) method. Due to fixed oxidation state of Zn2+ ions, the substitution of Zn2+ for Co2+ suppresses the oxygen adsorption of YBaCo4−xZnxO7. The substitution of Ga3+ for Co3+ also decreases the oxygen absorption capacity of YBaCo4−xGaxO7. This can be explained by the strong affinity of Ga3+ ions towards the GaO4 tetrahedron. Compared with Zn- and Ga-substituted samples, the drop of oxygen adsorption capacity is smallest for Fe-substituted samples because of the similar changeability of oxidation states of Co and Fe ions.

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Abstract  

The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)2(H2O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P21/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, =90.38(2)°, V=1.0806(2) nm3, Z=4, D c=2.97 g cm–3, µ=157.83cm–1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)2 H2O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6pz and 6py AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)2 H2O] is heated, ligand water is dissociated first and NO2 group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)2 H2O] has been derived. The lattice enthalpy and its lattice energy were also estimated.

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Abstract  

The thermal decomposition of strontium acetate hemihydrate has been studied by TG-DTA/DSC and TG coupled with Fourier transform infrared spectroscopy (FTIR) under non-isothermal conditions in nitrogen gas from ambient temperature to 600°C. The TG-DTA/DSC experiments indicate the decomposition goes mainly through two steps: the dehydration and the subsequent decomposition of anhydrous strontium acetate into strontium carbonate. TG-FTIR analysis of the evolved products from the non-oxidative thermal degradation indicates mainly the release of water, acetone and carbon dioxide. The model-free isoconversional methods are employed to calculate the E a of both steps at different conversion α from 0.1 to 0.9 with increment of 0.05. The relative constant apparent E a values during dehydration (0.5<α<0.9) of strontium acetate hemihydrate and decomposition of anhydrous strontium acetate (0.5<α<0.9) suggest that the simplex reactions involved in the corresponding thermal events. The most probable kinetic models during dehydration and decomposition have been estimated by means of the master plots method.

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Abstract  

This paper reports on the qualitative and quantitative analyses of light hydrocarbons produced by radiation degradation of N,N-diethylhydroxylamine. The results show that when the absorbed doses are between 10 and 1000 kGy, the main light hydrocarbons are methane, ethane, ethene, propane and n-butane. Their volume fractions are increased with the increase of the dose. The volume fraction of ethene is also increased at low doses with the increase of the dose, but it is decreased with the increase of dose at high doses.

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Abstract  

Solid complexes of M(His)2Cl2 nH2O (M=Mn, Co, Ni, Cu) of MnCl26H2O, CoCl26H2O, NiCl26H2O, CuCl22H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses, IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter. And the standard enthalpies of formation of the complexes have been calculated as well.

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Abstract  

The solid complexes of Cr(NO3)3 with L-α-amino acids (AA=Val, Leu, Thr, Arg, Phe and Try) have been prepared in 95% alcoholic, the compositions of which were identified as the general formula Cr(AA)2(NO3)32H2O by elemental and chemical analyses. The bonding characteristics of the title complexes were characterized by IR, indicating that nitrogen and oxygen atoms in the ligands coordinated to Cr3+ in a bidentate fashion. With the aid of TG-DTG and IR techniques, the complexes were subjected to thermal decomposition in an atmosphere of oxygen, presuming that the decompositions of the complexes consist of two steps and the complexes were decomposed into chromium hemitrioxide after undergoing dehydration and skeleton splitting of the complexes. The constant volume energies of combustion of the complexes were determined by a RBC-P type rotating-bomb calorimeter. According to Hess's law, the standard enthalpies of formation of the complexes were calculated as (-1831.404.40), (-2542.036.13), (-1723.813.99), (-2224.313.02), (-2911.616.53) and (-659.327.42) kJ mol-1, respectively.

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Abstract

Thermal decomposition of N,N′-diphenylguanidine (DPG) was investigated by simultaneous TG/DSC-FTIR techniques under nonisothermal conditions. Online FTIR measurements illustrate that aniline is a major product of DPG decomposition. The observation that the activation energy depends on the extent of conversion indicates that the DPG decomposition kinetics features multiple processes. The initial elimination of aniline from DPG involves two pathways because of the isomerization of DPG. Mass spectrometry and thin film chromatography suggest that there are two major intermediate products with the major one of C21N3H17. The most probable kinetic model deduced through multivariate nonlinear regression method agrees well with the experimental data with a correlation coefficient of 0.9998. The temperature-independent function of conversion f(α), activation energy E and the pre-exponential factor A of DPG decomposition was also established through model-fitting method in this research.

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Abstract

This study aimed to explore the inhibitory effect and mechanism of the total alkaloids of Dendrobium officinale Kimura et Migo (DENA) against cholesterol esterase (CE). DENA was characterised by SEM, 1H NMR, and X-ray diffraction (XRD). The inhibitory effect and mechanism of DENA against CE were investigated through fluorescence chromatography, circular dichroism, and molecular docking. DENA inhibited CE activity (IC50 = 1.08 ± 0.09 mg mL−1), characterised by a non-competitive inhibition mechanism. Furthermore, DENA induced a fluorescence quenching in CE, causing a blue shift in the λmax. This coincided with a transition in the secondary structure of CE from a layered to a helical structure by circular dichroism, indicating a significant reduction in its stability. Moreover, molecular docking confirmed that DENA binds to amino acid residues in the enzyme through hydrogen bonds and hydrophobic interactions, leading to structural changes and reduced enzyme activity. These results suggest DENA has the potential to lower blood lipid levels by inhibiting CE activity.

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