A comparative study on the extraction effects of common agents on collagen-based binders in mural paintings

In this paper, a comparative study was conducted on the extraction effects of six agents for collagen-based mural painting binders. These agents were used to extract the residual proteins in the non-aged and thermal aged samples. The protein extraction efficiencies of different extracting agents were quantitatively determined by bicinchoninic acid (BCA) method, and then processed by multivariate analysis of variance (MANOVA). The impact of the extraction process on the protein structure was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet absorption spectrum (UV) and circular dichroism (CD). The results showed that, for both non-aged and aged samples, the extraction efficiency of 2 M guanidine hydrochloride (GuHCl) was significantly higher than the other five agents, with less damage to the protein structure during the extraction process.

Study on Chromaticity Removal from Mineral Processing Wastewater with Salicylic Hydroxamic Acid by Granular Activated Carbon Catalyzed Ozonation

Salicylic hydroxamic acid is a novel flotation reagent used in mineral processing. However, it impacts the flotation wastewater leaving behind high chromaticity which limits its reuse and affects discharge for mining enterprises. This study researched ozonation catalyzed by the granular activated carbon (GAC) method to treat the chromaticity of the simulated mineral processing wastewater with salicylic hydroxamic acid. The effects of pH value, ozone (O3) concentration, GAC dosage, and reaction time on chromaticity and chemical oxygen demand (CODCr) removal were discussed. The results of individual ozonation experiments showed that the chromaticity removal ratio reached 79% and the effluent chromaticity exceeded the requirement of reuse and discharge when the optimal experimental conditions were pH value 3, ozone concentration 6 mg/L, and reaction time 40 min. The orthogonal experimental results of catalytic ozonation with GAC on chromaticity removal explained that the chromaticity removal ratio could reach 96.36% and the chromaticity of effluent was only 20 when the optimal level of experimental parameters was pH value 2.87, O3 concentration 6 mg/L, GAC dosage 0.06 g/L, reaction time 60 min respectively. The degradation pathway of salicylic hydroxamic acid by ozonation was also considered based on an analysis with ultraviolet absorption spectrum and high-performance liquid chromatography (HPLC).

Failure of Molecular Dynamics to Provide Appropriate Structures for Quantum Mechanical Description of the Aqueous Chloride Ion Charge-Transfer-to-Solvent Ultraviolet Spectrum

The lowest band in the experimental charge-transfer-to-solvent ultraviolet absorption spectrum of aqueous chloride ion is studied by experiment and computation. Interestingly, the experiments indicate that at concentrations up to at...

Antioxidant Stress and Anticancer of Peptide Chelate Selenium Element in vitro

This contribution reports a facile synthesis of anticancer bioactive peptides (ACBP) - functionalized selenium particles (ACBP-S-Se) with enhanced anticancer activities and a detailed mechanistic evaluation of its regulation of oxidative stress in vitro. Structural and chemical characterizations were proved by ultraviolet absorption spectrum (UV), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Nuclear magnetic resonance carbon (13C NMR) and hydrogen spectra (H NMR), scanning electron microscope (SEM), energy dispersive X-ray spectrom (EDX) and inductively coupled plasma mass spectrometry (ICP-MS). The results show that ACBP are effectively sulfhydrylation modification with S-acetylmercaptosuccinic anhydride (SAMSA) via chemical absorption. After the polypeptide was modified by sulfhydrylation, there were many sulfhydryl groups on the molecule, and the sulfhydryl group was used as the binding site of Se. A panel of selected human cancer cell lines demonstrated high susceptibility toward ACBP-S-Se and displayed significantly reduced proliferative abilities. Finally, the results presented herein suggest bioactive peptide chelate selenium element effectively inhibited the proliferation of MKN-45 and MKN-74 cell in vitro, which in turns allowed the successful application of the ACBP-S-Se in highly complex human cell lines. The related the regulation of oxidative stress gene is CDKN1A, CCNB1, TXN and MAP3K5, while CDKN1A and TXN have ability to protecting cells to reduce oxidative stress and promoting cell growth arrest. Therefore, the great potential exhibited by ACBP-S-Se could make them an ideal candidate as a chemotherapeutic agent for human cancers, especially for gastric cancer.

Role of Hemibonding in the Structure and Ultraviolet Spectroscopy of the Aqueous Hydroxyl Radical

The presence of a hemibond in the local solvation structure of the aqueous hydroxyl radical has long been debated, as its appearance in <i>ab initio</i> simulations based on density functional theory is sensitive to self-interaction error (favoring a two-center, three-electron hemibond) but also to finite-size effects. Simulations reported here use a mixed quantum mechanics/molecular mechanics (QM/MM) framework in a very large periodic simulation cell, in order to avoid finite-size artifacts and to facilitate testing of various density functionals, in order to probe the effects of delocalization error. The preponderance of hemibonded structures predicted by generalized gradient approximations persists in simulations using the hybrid functionals B3LYP and PBE0, but is reduced to a minor population if the fraction of exact exchange is increased significantly. The hemibonded population is also small in simulations employing the long-range corrected functional LRC-wPBE. Electronic spectra are computed using time-dependent density functional theory, and from these calculations emerges a consensus picture in which hemibonded configurations play an outsized role in the absorption spectrum, even when present as a minority species. An intense 1b₂ (H₂O) --> 2p (OH) charge-transfer transition in hemibonded configuration of the radical proves to be responsible for an absorption feature at 230~nm that is strongly shifted with respect to the gas-phase absorption at 307 nm, but this intense feature is substantially diminished in aqueous geometries where the hemibond is absent. Although not yet sufficient to quantitatively establish the population of hemibonded OH(aq), these simulations do suggest that its presence is revealed by the strongly shifted ultraviolet absorption spectrum of the aqueous radical.<br>

Role of Hemibonding in the Structure and Ultraviolet Spectroscopy of the Aqueous Hydroxyl Radical

The presence of a hemibond in the local solvation structure of the aqueous hydroxyl radical has long been debated, as its appearance in <i>ab initio</i> simulations based on density functional theory is sensitive to self-interaction error (favoring a two-center, three-electron hemibond) but also to finite-size effects. Simulations reported here use a mixed quantum mechanics/molecular mechanics (QM/MM) framework in a very large periodic simulation cell, in order to avoid finite-size artifacts and to facilitate testing of various density functionals, in order to probe the effects of delocalization error. The preponderance of hemibonded structures predicted by generalized gradient approximations persists in simulations using the hybrid functionals B3LYP and PBE0, but is reduced to a minor population if the fraction of exact exchange is increased significantly. The hemibonded population is also small in simulations employing the long-range corrected functional LRC-wPBE. Electronic spectra are computed using time-dependent density functional theory, and from these calculations emerges a consensus picture in which hemibonded configurations play an outsized role in the absorption spectrum, even when present as a minority species. An intense 1b₂ (H₂O) --> 2p (OH) charge-transfer transition in hemibonded configuration of the radical proves to be responsible for an absorption feature at 230~nm that is strongly shifted with respect to the gas-phase absorption at 307 nm, but this intense feature is substantially diminished in aqueous geometries where the hemibond is absent. Although not yet sufficient to quantitatively establish the population of hemibonded OH(aq), these simulations do suggest that its presence is revealed by the strongly shifted ultraviolet absorption spectrum of the aqueous radical.<br>