An Investigation into the Stability Source of Collagen Fiber Modified Using Cr(III): An Adsorption Isotherm Study.

The enhanced hydrothermal stability of leather, imparted by little Cr(III), has traditionally been ascribed to strong coordinate bonds. However, this explanation falls short when considering that the heat-induced shrinking of collagen fiber is predominantly driven by rupturing weak H-bonds. This study explored the stability source via adsorption thermodynamics using collagen fiber as an adsorbent. Eleven isotherm models were fitted with the equilibrium dataset. Nine of these models aptly described Cr(III) adsorption based on the physical interpretations of model parameters and error functions. The adsorption equilibrium constants from six models could be transformed into dimensionless thermodynamic equilibrium constants. Based on the higher R2 of the van't Hoff equation, thermodynamic parameters (∆G°, ∆H°, ∆S°) from the Fritz-Shluender isotherm model revealed that the adsorption process typifies endothermic and spontaneous chemisorption, emphasizing entropy increase as the primary driver of Cr(III) bonding with collagen. Thus, the release of bound H2O from collagen is identified as the stability source of collagen fiber modified by Cr(III). This research not only clarifies the selection and applicability of the isotherm model in a specific aqueous system but also identifies entropy, rather than enthalpy, as the principal stability source of Cr-leather. These insights facilitate the development of novel methods to obtain stable collagen-based material.

Variations in the Crystal Lattice of Tb-Dy-Fe Magnetostrictive Materials: The Lattice Constant Disturbance.

In Tb-Dy-Fe alloy systems, Tb0.29Dy0.71Fe1.95 alloy shows giant magnetostrictive properties under low magnetic fields, thus having great potential for transducers, microsensors, and other applications. The C15 cubic crystal structure of Tb-Dy-Fe has long been thought to be the source of giant magnetostriction. It is surprising that such a highly symmetrical crystal structure exhibits such a large magnetostrictive strain. In this work, the lattice parameters of Tb0.29Dy0.71Fe1.95 magnetostrictive materials were studied by processing atomic-resolution images. The selected area diffraction patterns show a face-centered cubic structure, but the fast Fourier transform diagram shows that the cubic structure has obvious distortion. The lattice parameters obtained by geometric phase analysis (GPA) and Gaussian model-based fitting and calculation show that the lattice constants a, b, and c are not strictly equal, and small disturbance of the lattice constants occurs based on the cubic structure. The actual crystal structure of the Tb-Dy-Fe material is a slightly disturbed cubic structure. This variation in the crystal lattice is mainly caused by the inhomogeneous composition and may be related to the giant magnetostrictive properties of Tb-Dy-Fe alloy.

Lattice Deformation of Tb0.29Dy0.71Fe1.95 Alloy during Magnetization.

In Tb-Dy-Fe alloy systems, Tb0.29Dy0.71Fe1.95 alloy shows giant magnetostrictive properties under low magnetic fields, thus having great potential for transducer and sensor applications. In this work, the lattice parameters of Tb0.29Dy0.71Fe1.95 compounds as a function of a magnetic field were investigated using in situ X-ray diffraction under an applied magnetic field. The results showed that the c-axis elongation of the rhombohedral unit cell was the dominant contributor to magnetostriction at a low magnetic field (0-500 Oe). As the magnetic field intensity increased from 500 Oe to 1500 Oe, although the magnetostrictive coefficient continued to increase, the lattice constant did not change, which indicated that the elongated c-axis of the rhombohedral unit cell rotated in the direction of the magnetic field. This rotation mainly contributed to the magnetostriction phenomenon at magnetic fields of above 500 Oe. The structural origin of the magnetostriction performance of these materials was attributed to the increase in rhombohedral lattice parameters and the rotation of the extension axis of the rhombohedral lattice.

Parallel Aluminum-Cobalt Oxide Nanosheet Arrays with High-Temperature Ferromagnetism.

Parallel nanomaterials possess unique properties and show potential applications in industry. Whereas, vertically aligned 2D nanomaterials have plane orientations that are generally chaotic. Simultaneous control of their growth direction and spatial orientation for parallel nanosheets remains a big challenge. Here, a facile preparation of vertically aligned parallel nanosheet arrays of aluminum-cobalt oxide is reported via a collaborative dealloying and hydrothermal method. The parallel growth of nanosheets is attributed to the lattice-matching among the nanosheets, the buffer layer, and the substrate, which is verified by a careful transmission electron microscopy study. Furthermore, the aluminum-cobalt oxide nanosheets exhibit high-temperature ferromagnetism with a 919 K Curie temperature and a 5.22 emu g-1 saturation magnetization at 300 K, implying the potential applications in high-temperature ferromagnetic fields.

Graphitic N-doped biochar for superefficient uranium recycling from nuclear wastewater.

N-doped biochar (AL-N/BC) prepared by pyrolyzing lignin in various temperatures manifested superefficient performance for uranium (U) recycling from nuclear wastewater. The optimist AL-N/BC-700 showed higher adsorption capacity of 25,000 mg/g and faster kinetics of 4100 g·min-1·mg-1 than the most of reported adsorbents, and excellent adsorption-desorption capability (adsorption rate > 90 % and desorption rate > 70 % after 12 cycles). Moreover, the high applicability of AL-N/BC-700 was verified by its superefficient U(VI) adsorption performance in a broad working pH range, various water matrices, and high irradiation stability. Furthermore, the adsorption mechanism discloses the significant role of graphitic N, rather than pyridinic N or pyrrolic N, for U(VI) adsorption. Overall, this work not only presents an applicable approach to alleviate the increasingly serious energy crisis via recycling U(VI) from nuclear wastewater, but also enriches the method of synthesizing N-doped materials for U(VI) adsorption.

Highly efficient U(VI) capture from nuclear wastewater by an easily synthesized lignin-derived biochar: Adsorption performance and mechanism.

The efficient recycling of uranium (U) by adsorbents remains challenging due to the strong interference from coexisting impurities, insufficient desorption efficiency, and weak irradiation instability. In this work, a novel lignin-derived biochar (AL/BC) with high surface area and abundant functional groups was developed through a green and simple pyrolysis process, and an adsorbent for U(VI) capture was used. The optimist AL/BC-600 exhibited ultrahigh adsorption capacity for U(VI) of 4007 mg/g, possessing a wide pH range of 1-11, and powerful anti-interference ability when coexisting with various common cations and anions. In addition, AL/BC-600 showed high tolerance even under strong irradiation at a dose of 350 kGy. Most importantly, after the tenth round of the adsorption-desorption cyclic utilization, the adsorption efficiency and desorption rate of AL/BC-600 were actually over 95% and 80%, respectively. Hence, this study provides a green and simple process for synthesizing a novel adsorbent for highly efficient U(VI) capture, not only paving a path for alleviating the increasingly serious energy crisis, but also facilitating the low-carbon and circular development of lignin.

Simultaneously efficient adsorption and highly selective separation of U(VI) and Th(IV) by surface-functionalized lignin nanoparticles: A novel pH-dependent process.

The simultaneous removal and selective separation of U(VI) and Th(IV) via adsorption remain challenging due to their strong mobility, reactivity, and similar chemical properties. Thus, a surface-functioned lignin nanoparticle (AL-PEI) was synthesized to adsorb U(VI)/Th(IV) in a unitary system via a pH-dependent process. In alkaline solution, AL-PEI exhibited excellent adsorption performance, and the maximum adsorption capacities for U(VI) and Th(IV) reached 392 and 396 mg/g, respectively. Discrepantly in acidic solution, the adsorption performance of AL-PEI for U(VI) could still reach a high capacity (332 mg/g), whereas highly limited adsorption capacity (less than 40 mg/g) for Th(IV) was obtained, and the separation factor of U(VI) from U(VI)-Th(IV) matrix significantly reached 6662 in 3 M of the HNO3 medium. The simultaneously efficient adsorption in alkaline solution and highly selective separation performance in acidic solution of AL-PEI also showed excellent anti-ions interference capacities, high reusability, and strong stability. This study is the first to apply lignin fabricating radiation-resistant adsorbent material, and the adsorbent displays good performance for U(VI)/Th(IV) removal and selective separation via a novel pH-dependent process, which is important to the green and sustainable development of nuclear energy and environmental protection.

Effects of W Alloying on the Lattice Distortion and Wear Behavior of Laser Cladding AlCoCrFeNiWx High-Entropy Alloy Coatings.

Friction and wear properties of hot working die steel at above 800 °C are of particular interest for high temperature applications. Here, novel AlCoCrFeNiWx high-entropy alloy (HEA) coatings have been fabricated on the surface of hot working die steel by laser cladding. The effects of the as-prepared AlCoCrFeNiWx HEA coatings on the microstructure and high temperature friction and wear behavior of hot working die steel are investigated through scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS). Having benefited from the formation of W-rich intermetallic compounds after the addition of W elements, the high temperature wear resistance of the coatings is obviously improved, and friction coefficient shows a large fluctuation. The microstructural characteristics of the AlCoCrFeNiWx HEA coatings after the high temperature wear resistance test shows a highly favorable impact on microstructure stability and wear resistance, due to its the strong lattice distortion effect of W element on BCC solid solutions and the second phase strengthening of the W-rich intermetallic compounds. These findings may provide a method to design the high temperature wear resistant coatings.

Host defense peptide LEAP-2 contributes to monocyte/macrophage polarization in barbel steed (Hemibarbus labeo).

The liver-expressed antimicrobial peptide 2 (LEAP-2) plays a vital role in host immunity against pathogenic organisms. In the present study, cDNA of the LEAP-2 gene was cloned and sequenced from the barbel steed (Hemibarbus labeo). The predicted amino acid sequence of the barbel steed LEAP-2 comprises a signal peptide and a prodomain, which is followed by the mature peptide. Sequence analysis revealed that barbel steed LEAP-2 belongs to the fish LEAP-2A cluster and that it is closely related to zebrafish LEAP-2A. We found that barbel steed LEAP-2 transcripts were expressed in a wide range of tissues, with the highest mRNA levels detected in the liver. In response to lipopolysaccharide (LPS) treatment, LEAP-2 was significantly upregulated in the liver, head kidney, spleen, gill, and mid intestine. A chemically synthesized LEAP-2 mature peptide exhibited selective antimicrobial activity against several bacteria in vitro. Moreover, LEAP-2, alone or in combination with LPS or phorbol 12-myristate 13-acetate, strongly induced a pro-inflammatory reaction in barbel steed monocytes/macrophages (MO/MФ), involving the induction of iNOS activity, respiratory burst, and the pro-inflammatory cytokines IFN-γ, TNF-α, and IL-1ß. Collectively, the results of this study indicate the importance of fish LEAP-2 in the M1-type polarization of MO/MΦ.

The effect of glycerol and 2-propanol on the molecular aggregation of collagen in solution.

The molecular aggregation of collagen solution (Col) in the presence of glycerol (Col-G) and 2-propanol (Col-P) was investigated. The transition temperature (Tm) of collagen, determined by ultra-sensitive differential scanning calorimetry, increased proportionally to the concentration of glycerol about 0.929 °C per 1M, while Tm decreased proportionally to the concentration of 2-propanol about 1.638 °C per 1M. The fluorescence spectra of collagen in solutions were detected by two-dimensional technique on the perturbation of the concentration of glycerol and 2-propanol and showed different results in Col-G and Col-P. The size of collagen aggregates in solutions was observed by dynamic light scattering. Compared with the aggregate size in Col, collagen aggregates became smaller in the presence of glycerol, whereas it grew larger in the presence of 2-propanol. Furthermore, the different extent of aggregation in Col, Col-G and Col-P influenced the self-assembly of collagen molecules under physiological conditions, and there were differences in the resulted fibril structures of Col, Col-G and Col-P after fibrillogenesis as determined by scanning electron microscopy. These results indicated that glycerol inhibited the collagen aggregates while 2-propanol promoted them in solution.

The influence of chondroitin 4-sulfate on the reconstitution of collagen fibrils in vitro.

Collagen fibrils were in vitro reconstituted from the aggregated collagen solution in the presence of a wide range of collagen/chondroitin 4-sulfate (Col/C4S) ratios. As revealed by turbidimetric measurement, the collagen fibril formation is significantly accelerated by C4S. The turbidity values of both the solution after 30 min preincubation at 4°C and the gels after 60 min preincubation at 37°C become larger with the increase of C4S amount. According to the results obtained from turbidimetric measurement and atomic force microscopy observation of solutions, it is predicted that the preincubation of Col/C4S blends at 4°C is necessary to initiate the Col/C4S binding and then promote the further lateral fusion of collagen aggregates in solution. The interactions between collagen and C4S are also vital in the growth phase of collagen self-assembly. Collagen quantitation data show that the amounts of collagen incorporated into self-assembled cofibrils increase a lot as a result of the presence of C4S. Differential scanning calorimetry measurement shows that the thermal stability of cofibrils keeps increasing with the ascending amount of incorporated C4S. It is suggested that the bound C4S might be captured inside the cofibrils acting as promoter and stabilizer. Atomic force microscopy and scanning electron microscopy observations of self-assembled fibrils indicate that the size increase of the self-assembled cofibrils depends on the lateral accretion of small collagen fibrils, while the self-assembly mode of collagen is not affected.

[Study on the effect of temperature on the conformation of cross-linked collagen by two-dimensional infrared correlation spectroscopy].

The Fourier transform infrared spectroscopy and two dimensional correlation analysis method were applied to study a denaturing process of uncross-linked collagen and cross-linked collagen during varying temperature. It was found that the intensity of typically characteristic absorptions of collagen decreased and its peak shifted to low frequency, The amide II central absorbance peak moved to a lower frequency by about 10 cm(-1), which indicated that the inter-chain hydrogen bonds which stabilized the triple helix conformation of collagen were disrupted during thermal denaturation, resulting in a conformational change. The intensity of auto-peak at 1 515 cm(-1) was maximum, which suggested that the temperature had a big impact on amide II. In comparison with uncross-linked collagen, the intensity of cross-peaks of cross-linked collagen was weaker, which demonstrated that the effect of temperature on the structure of cross-linked collagen was smaller, and the thermal stability properties of collagen solution could be improved by cross-linking. While the order of second structure changes of cross-linked collagen was different. These fundamental data should provide available information for understanding the relationship between the structure and function of cross-linked collagen.

The thermal behavior of collagen in solution: effect of glycerol and 2-propanol.

The thermal stability of different solutions of collagen (Col), collagen mixed with glycerol (Col-G) and collagen mixed with 2-propanol (Col-P) was studied by differential scanning calorimetry (DSC), viscosity and fluorescence. The DSC and viscosity methods showed that glycerol increased the denaturation temperature of collagen about 2°C, while 2-propanol decreased it about 2°C. The values of intrinsic viscosity ([η]) for Col, Col-G and Col-P were 21.67, 20.20 and 24.71 dl/g, respectively. Huggins coefficient (k(H)) increased in the presence of glycerol and decreased in the presence of 2-propanol. It was suggested that glycerol promoted the dissolution of collagen molecular aggregates while 2-propanol enhanced the aggregation. Fluorescence spectra were investigated within the temperature ranging from 15 to 45°C. By comparing the sign of peaks in the two-dimensional (2D) fluorescence correlation maps, the orders of peak response were ∼360, ∼410>297 nm for Col and Col-G, and 297>∼360, ∼410 nm for Col-P, respectively. These indicated that the respondences of tyrosine residues, excimer-like species and bityrosine on the perturbation of temperature were different in the presence of glycerol and 2-propanol.