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Amino acids as latent curing agents and their application in fully bio-based epoxy resins
No full textLatent curing agents are significantly important to develop one-component epoxy resins. However, the reported latent curing agents are from unsustainable fossil resources. Herein, a new type of latent curing agent-amino acids-was developed from bioresources. Amino acids can be naturally occurring and can also be synthesized from bio-based compounds. The latent curing feature and mechanism were revealed through investigation of curing kinetics and small-molecule model curing reaction. A bio-based amino acid containing amide bond (PDA-MAH) was synthesized from 1,5-pentanediamine and maleic anhydride, and used together with a bio-based epoxy monomer from itaconic acid (EIA) to achieve a fully bio-based one-component epoxy system. The obtained epoxy network exhibited significantly enhanced glass transition temperature, tensile strength and Young's modulus compared with the control amino acid/EIA system due to the hydrogen bonding from the amide bonds. In addition, the epoxy network exhibited excellent degradability under alkaline conditions
Pitfalls and solutions for perovskite transparent conductors
No full textTransparent conductors-nearly an oxymoron-are in pressing demand, as ultrathin-film technologies become ubiquitous commodities. With current solutions relying on nonabundant elements, it has recently been suggested that perovskites-such as SrVO3 and SrNbO3-could serve as next generation transparent conductors. In these, strong electronic correlations push the plasma frequency below the visible spectrum to curtail absorption. Our ab initio calculations and analytical insights establish, however, that the required effective mass enhancement unavoidably comes at a price: An increased scattering that causes substantial optical absorption above the plasma edge. We circumvent this dilemma and identify high-grade perovskite transparent conductors, relying on an interplay of hole doping, larger bandwidths, separation of bands, but only mild mass enhancements
Self-healing Polymeric Hydrogels: Toward Multifunctional Soft Smart Materials
No full textThe concept of self-healing that involves a built-in ability to heal in response to damage wherever and whenever it occurs in a material, analogous to the healing process in living organisms, has emerged a couple of decades ago. Driven primarily by the demands for life-like materials and soft smart materials, therefore, the development of self-healing polymeric hydrogels has continually attracted the attention of the scientific community. Here, this review is intended to give an in-depth overview of the state-of-the-art advances in the field of self-healing polymeric hydrogels. Specifically, recently emerging trends in self-healing polymeric hydrogels are summarized, and notably, recommendations to endow these hydrogels with fascinating multi-functionalities including luminescence, conductivity/magnetism and shape memory etc. are presented. To close, the current challenges and future opportunities in this field are also discussed
Theoretical Insights into the Reduction Mechanism of Np(VI) with Phenylhydrazine
No full textEffectively adjusting and controlling the valence state of neptunium from the spent fuel reprocessing process is essential to separating neptunium. Hydrazine and its derivatives as free-salt reductants have been experimentally demonstrated to effectively reduce Np(VI) to Np(V). We have theoretically investigated the reduction mechanisms of Np(VI) with hydrazine and three derivatives (HOC2H4N2H3, CH3N2H3, and CHON2H3) in previous works. Herein, we further explored the reduction reaction of Np(VI) with phenylhydrazine (C6H5N2H3) including the free radical ion mechanism and the free radical mechanism. Potential energy profiles (PEPs) indicate that the rate-determining step of both mechanisms is the first stage. Moreover, for the free radical ion mechanism, phenylhydrazine possesses better reduction ability to Np(VI) compared to HOC2H4N2H3, CH3N2H3, and CHON2H3, which falls completely in line with the experimental results. Additionally, the analyses of the quantum theory of atoms in molecules (QTAIM), natural bond orbitals (NBOs), electron localization function (ELF), and localized molecular orbitals (LMOs) have been put forward to elucidate the bonding evolution for the structures of the reaction pathways. This work offers insights into the reduction mechanism of Np(VI) with phenylhydrazine from the theory point of view and contributes to design more high-efficiency reductants for the separation of U/Np and Np/Pu in spent fuel reprocessing
A new low-density hydrogel-based matrix with hollow microsphere structure for weight reduction of microwave absorbing composites
No full textA new low-density hydrogel-based composites matrix, super light clay (SLC), with a low density of 0.24 g/cm3, was prepared by mixing the hydrogel and hollow glass microspheres. The swelling-adsorption effect of hydrogel was used to adsorb carbonyl iron powder (CIP) on the surface of hollow microspheres. Benefitting from the existence of microporous structure and surface adsorption, the electromagnetic absorption performance of the obtained SLC/CIP composite microwave absorbing materials (MAMs) were greatly boosted. The results show that the composite filled with 11 vol% of the CIP had a minimum reflection loss (RL) of -45.3 dB and an effective absorption bandwidth (EAB, with a RL of less than -10 dB) of 4.81 GHz. In addition, the swelling-adsorption mechanism of the hydrogel-based SLC matrix and the high-frequency electromagnetic wave attenuation mechanisms have been also discussed. The environmentally friendly low-density matrix is of great significance fo
MAX phase Zr2SeC and its thermal conduction behavior
No full textThe elemental diversity is crucial to screen out ternary MAX phases with outstanding properties via tuning of bonding types and strength between constitutive atoms. As a matter of fact, the interactions between M and A atoms largely determine the physical and chemical properties of MAX phases. Herein, Se element was experimentally realized to occupy the A site of a MAX phase, Zr2SeC, becoming a new member within this nano-laminated ternary carbide family. Comprehensive characterizations including Rietveld refinement of X-ray Diffraction and atom-resolved transmission electron microscopy techniques were employed to validate this novel MAX phase. The distinct thermal conduction behaviors emerged are attributed to the characteristic interactions between Zr and Se atoms
High Li-Ion Conductivity Artificial Interface Enabled by Li-Grafted Graphene Oxide for Stable Li Metal Pouch Cell
No full textThe fragile electrolyte/Li interface is responsible for the long-lasting consumption of Li resources and fast failure of Li metal batteries. The polymer artificial interface with high mechanical flexibility is a promising candidate to maintain the stability of the electrolyte/Li interface; however, sluggish Li-ion transportation of the conventional polymer interface hinders the application. In this work, Li-functionalized graphene oxide (GO-ADP-Li-3), which is synthesized by covalent grafting of adenosine 5'-diphosphate lithium on GO nanosheets, is used as a functional additive to improve the Li-ion conductivity of the polymer artificial interface based on PVDF-HFP/LiTFSI. The enhanced Li-ion conductivity is contributed by accelerated Li-ion hopping at the surface between polymer chains and functionalized GO as well as the reduced crystallization degree of PVDF-HFP by this novel additive. The use of this modified polymer as an artificial interface on Li foil enables highly reversible Li stripping/plating and a high capacity retention of 78.4% after 150 cycles for a 0.2 A h Li metal pouch cell (Li/NCM811, strictly following practical conditions). This Li-grafted strategy on GO sheets provides an alternative for designing a compatible electrolyte/Li interface for practical Li metal batteries
Phosphonate-Functionalized Ionic Liquid: A New Surface Modifier Contributing to the Enhanced Enrichment of Phosphorylated Peptides
No full textPhosphopeptide enrichment with high selectivity and detection sensitivity is essential for phosphoproteomic studies and remains a long-standing challenge. In this study, new immobilized metal affinity chromatography nanocomposite adsorbents with a phosphonate-functionalized ionic liquid (PFIL) as a surface modifier are successfully prepared via a reaction sequence of amination, quaternization, phosphonate hydrolyzation, and metal immobilization. Taking advantages of integrated features of a flexible and strong tripodal phosphonate chelator, a hydrophilic ionic liquid linker, a large surface area, and the size-exclusion effect, the resulting nanocomposite G@mSiO(2)-PFIL-Ti4+ exhibits excellent detection sensitivity to enrich phosphorylated peptides from a tryptic beta-casein digest (0.15 fmol), and superior enrichment selectivity to capture phosphorylated peptides from a digest mixture of beta-casein and bovine serum albumin (a molar ratio of 1:10,000). Strong immobilization of tripodal chelation to metal ions endows the nanocomposite adsorbent with high tolerance to experimental conditions, and thus excellent reusability of the adsorbent has been achieved without remarkable loss of enrichment efficiency for 10 cycles. Due to the excellent size-exclusion effect, high enrichment specificity of G@mSiO(2)-PFIL-Ti4+ to phosphopeptides has been observed and 23 endogenous phosphopeptides have been captured from human saliva. In addition, 924 phosphopeptides (enrichment specificity, 56.1%) have been identified from the tryptic digest of mouse brain lysate. Particularly, six of 975 phosphorylation sites were Alzheimer's disease-related hyperphosphorylation sites within tau protein. These results demonstrate that G@mSiO(2)-PFIL-Ti4+ nanocomposite affinity materials show great application potential for a proteomic study of complicated biological samples
Realization of tunable artificial synapse and memory based on amorphous oxide semiconductor transistor (vol 7, 10997, 2017)
No full textEffect of Co/Ni Substituting Fe on Magnetocaloric Properties of Fe-Based Bulk Metallic Glasses
No full textIn this work, Fe80-xMxP13C7 (M = Co, Ni; x = 0, 5 and 10 at.%) bulk metallic glasses (BMGs) were prepared, and the effect of the Co/Ni elements substitution for Fe on the magnetocaloric properties of Fe80P13C7 BMG has been investigated systematically. The Curie temperature (T-C) of the present Fe-based BMGs increases with the substitution of Fe by Co/Ni. The magnetic entropy change (Delta S-M) of the present Fe-based BMGs increases first and then decreases with the increase of Fe substituted by Co, but monotonically decreases with the increase of Fe substituted by Ni. Among the present Fe-based BMGs, the Fe75Co5P13C7 BMG exhibits the maximum Delta S-M value of 5.21 J kg(-1) K-1 at an applied field of 5 T, which is the largest value among Fe-based amorphous alloys without any rare earth elements reported so far. The present Fe-based BMGs exhibit the large glass forming ability, tunable T-C and enhanced Delta S-M value, which are beneficial for magnetic refrigerant materials