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In this study, the composition and content of vitamin D and its esters in 108 human milk samples from different lactation stages (colostrum on days 0–7, transition milk on days 8–15 , and mature milk after day 16) were analyzed by ultra-high performance liquid chromatography/quadrupole time of flight mass spectrometry (UPLC/Q-TOF-MS). The results showed that human milk contained 4 kinds of vitamin D and 20 kinds of vitamin D esters, 16, 18 and 14 kinds of vitamin D esters being found in colostrum, transition milk and mature milk, respectively. During the whole lactation period, the average contents of vitamin D2 and 25(OH)-D3 in colostrum were highest, 26.83 and 160.67 ng/L, respectively; the average content of vitamin D3 in transition milk was highest, 119.87 ng/L; and the average content of 1,25(OH)2-D3 in mature milk was highest, 1.82 ng/L. The average contents of vitamin D esters in colostrum, transition milk and mature milk were 11.89, 10.73 and 11.47 ng/L, respectively, and the content of vitamin D2 tetradecenoate (C14:1) was highest throughout the lactation period. Through partial least squares-discriminant analysis (PLS-DA), colostrum, transition milk and mature milk could be well separated, indicating that the types and contents of vitamin D and vitamin D esters in human milk change from colostrum to mature milk. There was a correlation between different vitamin D esters. This study could provide data support for the development of infant formula.

The development of nanomaterials is crucial to upgrading of modern industry. MXene nanosheets have attracted significant attention due to their superb resistance to permeation, diverse surface chemical properties, impressive mechanical properties, and metal‐like electrical and thermal conductivity, etc., providing unique advantages in various technical fields. When MXene nanosheets are combined with polymers to form functional coatings, their applications span multiple fields, including anticorrosion, wear resistance, flame‐retardancy, electromagnetic interference (EMI) shielding, and de‐icing. This review, in conjunction with MXene's barrier property, lubricity, thermal stability, conductivity, and photothermal conversion property, discusses in detail the various applications of MXene‐based polymer coatings. Additionally, it examines the dispersion and interaction of MXene within polymer coatings and the role of functionalized MXene in polymers. Finally, based on the current research status and emerging needs, the development challenges and future research opportunities of MXene‐based polymer coatings in a targeted manner are discussed. This review aims to summarize the existing research results and put forward an objective and fair point of view, providing a constructive reference for upgrading modern nanofunctional polymer coatings. [ABSTRACT FROM AUTHOR]

For a vertex set X $X$ in a graph, the edge cut ∂ ( X ) $\partial (X)$ is the set of edges with exactly one end vertex in X $X$. An edge cut ∂ ( X ) $\partial (X)$ is tight if every perfect matching of the graph contains exactly one edge in ∂ ( X ) $\partial (X)$. A matching covered bipartite graph G $G$ is a brace if, for every tight cut ∂ ( X ) $\partial (X)$, | X | = 1 $|X|=1$ or | X ¯ | = 1 $|\bar{X}|=1$, where X ¯ = V ( G ) ⧹ X $\bar{X}=V(G)\setminus X$. Braces play an important role in Lovász's tight cut decomposition of matching covered graphs. The bicontraction of a vertex v $v$ of degree two in a graph, with precisely two neighbours v 1 ${v}_{1}$ and v 2 ${v}_{2}$, consists of shrinking the set { v 1 , v , v 2 } $\{{v}_{1},v,{v}_{2}\}$ to a single vertex. The retract of a matching covered graph G $G$ is the graph obtained from G $G$ by repeatedly the bicontractions of vertices of degree two. An edge e $e$ of a brace G $G$ with at least six vertices is thin if the retract of G − e $G-e$ is a brace. McCuaig showed that every brace of order at least six has a thin edge. In a brace G $G$ of order six or more, Carvalho, Lucchesi and Murty proved that G $G$ has two thin edges, and conjectured that G $G$ contains two nonadjacent thin edges. Further, they made a stronger conjecture: There exists a positive constant c $c$ such that every brace G $G$ has c | V ( G ) | $c|V(G)|$ thin edges. By showing that, in every cubic brace G $G$ of order at least six, there exists a matching M $M$ of size at least | V ( G ) | ∕ 10 $|V(G)|\unicode{x02215}10$ such that every edge in M $M$ is thin, we prove that the above two conjectures hold for cubic braces. [ABSTRACT FROM AUTHOR]

Polyionic liquid hydrogels attract increasing attention due to their unique properties and potential applications. However, research on amino acid‐based polyionic liquid hydrogels is still in its infancy stage. Moreover, the effect of amino acid types on the properties of hydrogels is rarely studied to date. In this work, amino acid‐based polyionic liquid hydrogels (D/L‐PCAA hydrogels) are synthesized by copolymerizing vinyl choline–amino acid ionic liquids and acrylic acids using Al3+ as a crosslinking agent and bacterial cellulose (BC) as a reinforcing agent. The effects of amino acid types on mechanical and antimicrobial properties are systematically investigated. D‐arginine‐based hydrogel (D‐PCArg) shows the highest tensile strength (220.7 KPa), D‐phenylalanine‐based hydrogel (D‐PCPhe) exhibits the highest elongation at break (1346%), and L‐aspartic acid‐based hydrogel (L‐PCAsp) has the highest elastic modulus (206.9 KPa) and toughness (1.74 MJ m−3). D/L‐PCAsp hydrogels demonstrate stronger antibacterial capacity against Escherichia coli and Staphylococcus aureus, and D/L‐PCPhe hydrogels possess higher antifungal activity against Cryptococcus neoformans. Moreover, the resultant hydrogels exhibit prominent hemocompatibility and low toxicity, as well as excellent self‐healing capabilities (86%) and conductivity (2.8 S m−1). These results indicate that D/L‐PCAA hydrogel provides a promise for applications in wound dressings. [ABSTRACT FROM AUTHOR]

In recent years, self-healing conductive hydrogels have attracted much attention for their promising applications in flexible electronic devices. However, the development of integral conductive hydrogels with excellent mechanical, self-healing, anti-freezing and strain-sensitive performances remains a major challenge. In this study, a series of self-healing polyionic liquid (PIL) ionogels based on vinyl choline-amino acid ionic liquids (Cho-AA VILs) via hydrophobic association (HA) with high mechanical strength and electrical conductivity were prepared by micellar copolymerization. The effects of the amount and type of Cho-AA VILs on the performances of PIL ionogels were investigated. Due to the reversibility of dynamic coordination interactions, including hydrophobic association, hydrogen bonding as well as electrostatic interactions, the resulting PIL ionogels demonstrated favourable self-healing ability. The integration of the Cho-AA VILs enabled the PIL ionogels to provide sensitive, fast and stable strain sensing at room and low temperatures. Notably, the PIL ionogel sensor was capable of monitoring and distinguishing large and small human movements. These results indicated that Cho-AX ionogels have promising applications in intelligent and flexible electronic devices. [ABSTRACT FROM AUTHOR]