Divalent metal ions under low concentration environment improved the thermal gel properties of egg yolk

To improve the thermal gel properties of egg yolk, the effect of several valence metal ions (K+, Ca2+, Mg2+ and Fe3+) with different concentrations (0-0.72%) on the rheological, gel, and structural properties of egg yolk were investigated. Results showed that monovalent and divalent ions were beneficial to the formation of uniform and dense gel network, especially with the addition of 0.72% magnesium ion, which further improved gel hardness, water holding capacity (WHC) and viscoelastic properties, the properties of egg yolk gel increased with the increase of the concentration of mono-bivalent metal ions. Adding ferric ion remarkably increased the average particle size (d4,3) and apparent viscosity of egg yolk, destroying the disulfide bonds and the hydrophobic interactions in gel. Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectra analysis revealed that metal ions promoted the hydrophobic aggregation among egg yolk proteins and induced the transition of protein secondary structure from ordered to disordered. This work will provide a theoretical reference for the development of low salt and nutrient fortified egg yolk products.

Characterization of four thermogelled egg yolk varieties based on moisture and protein content

There are obvious differences between egg yolks of different varieties. Additionally, boiled eggs, which are widely liked and consumed globally, are nutrient rich. However, they absorb water in the esophagus during swallowing, and this result in an uncomfortable sensation. Here, we determined the moisture content and distribution as well as the protein contents and properties of 4 varieties of thermogelled egg yolks. Among the varieties, Green Shelled thermogelled egg yolk showed the highest protein content and solubility. Additionally, the ionic, hydrogen, and disulfide bonds corresponding to Rhode Island Red thermogelled egg yolk samples were the weakest, while the hydrophobic interaction force corresponding to the Hetian Dahei (HD) egg yolk samples was the weakest. Further, the distribution of the moisture contents of the 4 varieties was significantly different (P < 0.05). HD egg yolk showed the highest moisture content, and its bound and immobile moisture contents were significantly higher than those of the other 3 varieties. Egg yolk moisture content also affected free amino acid content, which was the highest for HD egg yolk. Therefore, owing to its high moisture content, HD egg yolk was conducive for chewing and swallowing and given its high free amino acid content, it also had a more suitable taste and flavor. The results of this study provide a theoretical basis for the application of egg yolks in food processing.

Molecular Design of β-Sheet Peptide for the Multi-Modal Analysis of Disease

Intermolecular forces constrain peptide conformation. However, the role of each intermolecular force in constraining peptide conformation remains poorly understood. In this work, we show that aromatic-aromatic interactions drive peptides into β-sheets, and the hydrophobic effect determines the assembly speed of peptides. By using intermolecular forces to artificially control the assembly of β-sheets, a multi-modal analytical system was developed that allows five readouts and dual qualitative-quantitative analysis, and satisfies both point-of-care testing (POCT) and laboratory-based testing. For Mycoplasma Pneumoniae diagnosis, this system eradicates misdiagnosis (from 30 % to 0 %) and broadens the linear range by three-fold, both of which are critical for guiding therapy. This work not only illustrates exact roles of intermolecular forces in driving the formation of β-sheets, but also provides a guideline for the construction of a multi-modal analytical system for disease diagnosis.

Physical driving force of actomyosin motility based on the hydration effect

We propose a driving force hypothesis based on previous thermodynamics, kinetics and structural data as well as additional experiments and calculations presented here on water-related phenomena in the actomyosin systems. Although Szent-Györgyi pointed out the importance of water in muscle contraction in 1951, few studies have focused on the water science of muscle because of the difficulty of analyzing hydration properties of the muscle proteins, actin, and myosin. The thermodynamics and energetics of muscle contraction are linked to the water-mediated regulation of protein-ligand and protein-protein interactions along with structural changes in protein molecules. In this study, we assume the following two points: (1) the periodic electric field distribution along an actin filament (F-actin) is unidirectionally modified upon binding of myosin subfragment 1 (M or myosin S1) with ADP and inorganic phosphate Pi (M.ADP.Pi complex) and (2) the solvation free energy of myosin S1 depends on the external electric field strength and the solvation free energy of myosin S1 in close proximity to F-actin can become the potential force to drive myosin S1 along F-actin. The first assumption is supported by integration of experimental reports. The second assumption is supported by model calculations utilizing molecular dynamics (MD) simulation to determine solvation free energies of a small organic molecule and two small proteins. MD simulations utilize the energy representation method (ER) and the roughly proportional relationship between the solvation free energy and the solvent-accessible surface area (SASA) of the protein. The estimated driving force acting on myosin S1 is as high as several piconewtons (pN), which is consistent with the experimentally observed force.

Interfacial Charge Transfer in Dye-Sensitized Solar Cells Using SCN-Free Terpyridine-Coordinated Ru Complex Dye and Co Complex Redox Couples

The efficiency of dye-sensitized solar cells (DSSCs) using Ru complex dyes and Co complex redox couples has been increased with a strategy to prevent charge recombination via the addition of bulky or lengthy peripheral units to the dyes. However, despite the efforts, most of the DSSCs are still suffering from nonunity quantum efficiency and fast recombination. We examine the effect of SCN ligand, which has been used for many Ru complex dyes and could attract positively charged Co complexes. We find that replacing the ligands with 2,6-bis(2'-(4'-trifluoromethyl)pyrazolyl)pyridine increases the quantum efficiency and electron lifetime. With the combination of the replacement of SCN ligands and the addition of bulky moiety, ∼80% external quantum efficiency is achieved. These suggest that not only the addition of a blocking effect but also the reduction of electrostatic and dispersion forces between dyes and Co complexes are essential to control the charge separation and recombination processes.

Enhanced Electron Lifetimes in Dye-Sensitized Solar Cells Using a Dichromophoric Porphyrin: The Utility of Intermolecular Forces

Electron lifetimes in dye-sensitized solar cells employing a porphyrin dye, an organic dye, a 1:1 mixture of the two dyes, and a dichromophoric dye design consisting of the two dyes using a nonconjugated linker were measured, suggesting that the dispersion force of the organic dyes has a significant detrimental effect on the electron lifetime and that the dichromophoric design can be utilized to control the effect of the dispersion force.