Inhibition of insulin fibrillation by carboxyphenylboronic acid-modified chitosan oligosaccharide based on electrostatic interactions and hydrophobic interactions.

A novel inhibitor, carboxyphenylboronic acid-modified chitosan oligosaccharide (COS-CPBA), was developed by coupling carboxyphenylboronic acid (CPBA) with chitosan oligosaccharide (COS) to inhibit insulin fibrillation. Extensive biophysical assays indicated that COS-CPBA could decelerate insulin aggregation, hinder the conformational transition from α-helix to ß-sheet structure, change the morphology of insulin aggregates and alter fibrillation pathway. A mechanism for the inhibition of insulin fibrillation by COS-CPBA was proposed. It considers that insulin molecules bind to COS-CPBA via hydrophobic interactions, while the positively charged groups in COS-CPBA exert electrostatic repulsion on the bound insulin molecules. These two opposite forces cause the insulin molecules to display extended conformations and hinder the conformational transition of insulin from α-helix to ß-sheet structure necessary for fibrillation, thus decelerating aggregation and altering the fibrillation pathway of insulin. The studies provide novel ideas for the development of more effective inhibitors of amyloid fibrillation.

Characteristics and Controlling Factors of Natural Fractures in Deep Carbonates of the Puguang Area, Sichuan Basin, China.

Understanding the types, characteristics, and controlling factors of natural fractures in deep and ultradeep carbonates is crucial for evaluating reservoir quality, optimizing well deployment, and comprehending their impact on hydrocarbon exploitation. Multiple types of natural fractures are widespread in the deep carbonates of the Feixianguan Formation in the Puguang area, northeastern Sichuan Basin, China, and the main controlling factors are complex. Based on geological, geophysical, and experimental data, this study defined fracture types and analyzed the fracture development characteristics in the deep Feixianguan carbonates. On this basis, the main geological factors that control the development and distribution of tectonic fractures were discussed by combining statistical and experimental analyses. Results indicate that natural fractures in the Feixianguan Formation can be genetically classified into tectonic and diagenetic fractures. Specifically, tectonic fractures include shear fractures and tensile fractures, in which the former are predominant. In the Feixianguan carbonates, tectonic shear fractures are mainly developed in the NE-SW and near E-W strikes, with dip angles mostly ranging from 30 to 70°. The majority of shear fractures appear on a small scale and have good effectiveness. The fracture heights and apertures are commonly less than 50 cm and 25 µm, respectively, and unfilled fractures account for more than half. The distribution and development of tectonic fractures are mainly controlled by lithology, mechanical stratigraphy, reservoir physical properties, diagenetic cementation, and faults. In the Feixianguan carbonates, tectonic fractures are more developed in crystalline dolomite. With the increasing thickness of mechanical stratigraphy, the fracture density decreases and the scale increases. The presence of early dissolution pores can prevent the formation of later tectonic fractures. Tectonic fractures in the NNW-SSE and near N-S strikes generally possess poor effectiveness due to multiple cementations after their formation. In the vicinity of faults, tectonic fractures generally stretch subparallel to the extension direction of the fault, and the development degree of fractures close to major faults is higher.

In Situ Surface-Initiated ATRP Mediated by Gallium-Based Liquid Metal Nanodroplets.

Surface-initiated atom transfer radical polymerization (SI-ATRP) is one of the most popular methods for surface modifications with functional polymer films, which has attracted significant attention in recent years. Herein, a facile method of gallium-based liquid metal (GLM) nanodroplets mediated SI-ATRP to prepare polymer brushes on GLM surfaces is reported. The ATRP initiator modified GLM (GLM-Br) nanodroplets act as a substrate for the in situ SI-ATRP and participate as a reducing agent to reduce Cu(II) deactivators to Cu(I) activators. UV-vis spectra confirm the feasibility of the in situ SI-ATRP and indicate that the thickness and density of polymer brushes play an important role in performing a successful ATRP on GLM nanodroplets surfaces. Homo- and block copolymers, poly(3-sulfopropyl methacrylate potassium salt) (PSPMA) and poly((2-dimethylamino)ethyl methacrylate-b-(3-sulfopropyl methacrylate potassium salt)) P(DMAEMA-b-SPMA) are successfully grafted to the GLM nanodroplets. Polymer brushes modified GLM nanodroplets show potential applications such as friction reduction and oil-water emulsion separation. GLM nanodroplets mediated SI-ATRP provides a novel and robust approach to preparing multifunctional GLM nanodroplets for different applications.

Knockdown of Adra2a Increases Secretion of Growth Factors and Wound Healing Ability in Diabetic Adipose-Derived Stem Cells.

Studies showed that compared to normal adipose-derived stem cells (ASCs), ASCs from type 2 diabetic (T2D) mice were less effective in treating diabetic cutaneous wounds. However, the mechanisms remain unclear. Our transcriptomic profiling comparison showed that the expression of α2A-adrenergic receptor (Adra2a) was significantly increased in ASCs from T2D mice (T2D ASCs). Therefore, the purpose of this study was to investigate whether the elevated Adra2a is involved in the diminished wound-healing capabilities of T2D ASCs. RNA-seq was used to compare the transcriptomic profiles of T2D and normal ASCs. The differential genes were verified by real-time RT-qPCR. Clonidine was used to active Adra2a, and lentivirus-mediated RNAi was used to knockdown Adra2a. The secretion and expression of growth factors were detected by enzyme-linked immunosorbent assay (ELISA) and real-time RT-qPCR, respectively. The cAMP and PKA activity were also detected. Wound healing abilities of various ASCs were assessed in T2D mouse excisional wound models. The results showed Adra2a agonist clonidine decreased the expression and secretion of growth factors, cAMP content, and activity of PKA in ASCs, while Adra2a knockdown T2D ASCs showed the opposite effects. Adra2a knockdown T2D ASCs also showed increased wound-healing capabilities compared to untreated T2D ASCs. Altogether, T2D increased Adra2a expression, which may subsequently decrease the expression and secretion of growth factors and eventually diminish the wound-healing capabilities of T2D ASCs. Adra2a knockdown can restore the secretion of growth factors in T2D ASCs and then accelerate the wound healing, which may provide a new possibility in the treatment of diabetic wounds.

Ni-Directed biphase N-doped Mo2C as an efficient hydrogen evolution catalyst in both acidic and alkaline conditions.

The development of efficient and low-cost catalysts is of great significance for the future application of the electrocatalytic hydrogen evolution reaction (HER). Herein, a series of Ni,N co-doped Mo2C nanostructures (Nix-Mo2C/N) with different Ni content levels are fabricated. The phase-directing effect of Ni on Mo2C/N is observed, which is in charge of the phase transformation of Mo2C/N from an α- to a ß-phase. At the optimized Ni-doping level, biphase Ni15-Mo2C/N exhibits outstanding HER activity under both acidic and alkaline conditions. In particular, under alkaline conditions, Ni15-Mo2C/N delivers an overpotential of only 105.0 mV, accompanied by a low Tafel slope of 44.96 mV dec-1. The performance is comparable to commercial 20% Pt/C and higher than most state-of-the-art Mo2C-based catalysts as well.

Promoting the Water-Reduction Kinetics and Alkali Tolerance of MoNi4 Nanocrystals via a Mo2 TiC2 Tx Induced Built-In Electric Field.

Mo-Ni alloy-based electrocatalysts are regarded as promising candidates for the hydrogen evolution reaction (HER), despite their vulnerable stability in alkaline solution that hampers further application. Herein, Mo2 TiC2 Tx MXene, is employed as a support for MoNi4 alloy nanocrystals (NCs) to fabricate a unique nanoflower-like MoNi4 -MXn electrocatalyst. A remarkably strong built-in electric field is established at the interface of two components, which facilitates the electron transfer from Mo2 TiC2 Tx to MoNi4 . Due to the accumulation of electrons at the MoNi4 sites, the adsorption of the catalytic intermediates and ionic species on MoNi4 is affected consequently. As a result, the MoNi4 -MX10 nanohybrid exhibits the lowest overpotential, even lower than 10% Pt/C catalyst at the current density of 10 mA cm-2 in 1 m KOH solution (122.19 vs 129.07 mV, respectively). Furthermore, a lower Tafel slope of 55.88 mV dec-1 is reported as compared to that of the 10% Pt/C (65.64 mV dec-1 ). Additionally, the MoNi4 -MX10 catalyst also displays extraordinary chemical stability in alkaline solution, with an activity loss of only 0.15% per hour over 300 h of operation. This reflects the great potential of using MXene-based interfacial engineering for the synthesis of a highly efficient and stable electrocatalyst.

Catalytic polysulfides immobilization within a S/C-Co-N hollow cathode obtained by nonthermal imprison route.

Lithium-sulfur (Li-S) batteries have hitherto attracted dramatic research interests as an optional high-energy output candidate to replace the traditional lithium-ion batteries on account of its high energy density and low cost. Nonetheless, their kinetics arrearage and detrimental "shuttling effect" caused by the migration of soluble lithium polysulfide (LiPS) intermediates severely limit its practical application. Here, by a nonthermal route sulfur is in-situ imprisoned into Co/N-codoped hollow carbon sphere (NC-Co) to construct an integrated S/C-Co-N hollow cathode (S@NC-Co) and directly applied in Li-S batteries, which effectively avoids complex template removal and sulfur infiltration process. The hollow NC-Co sphere not only restricts polysulfides migration via physical confinement but also enhances polysulfides conversion through redox-active electro-catalysis. Moreover, the hollow structure has large cavity offering sufficient space to accommodate volume expansion and excellent conductivity promising efficient electron/charge transfer. As a result, the batteries assembled by the S@NC-Co cathode achieve low polarization and high-rate capability (551 mAh g-1 at 4C). Remarkably, the batteries also present an outstanding long-term durability over 800 cycles at 1C, in which the capacity attenuation is merely 0.06 % per cycle. This work demonstrates a novel strategy in designing hierarchical structures or nanoreactors for electrochemical reactions and energy storage systems.

Polydimethylsiloxane-Assisted Catalytic Printing for Highly Conductive, Adhesive, and Precise Metal Patterns Enabled on Paper and Textiles.

Paper and textile are two ideal carriers in wearable and printed electronics because of their flexibility and low price. However, the porous and fibrous structures restrain their use in printed electronics because the capillary effect results in ink diffusion. Especially, conventional metal ink needs to be post-treated at high temperatures (>150 °C), which is not compatible with paper and textile. To address problems involved in ink diffusion and avoid high-temperature treatment, herein, a new strategy is proposed: screen-printing of high-viscosity catalytic inks combined with electroless deposition of metal layers on paper and textile substrates. The ink consists of Ag nanoparticles, a polydimethylsiloxane (PDMS) prepolymer, and a curing agent. PDMS as a viscoelastic matrix of catalysts plays key roles in limiting ink diffusion, enhancing interfacial adhesion between the substrate and metal layer, keeping metal flexible. As a demonstration, metal Cu and Ni are printed, respectively. The printed precision (diffusion < 1% on filter paper) can be controlled by adjusting the Ag content in the PDMS matrix; interfacial adhesion can be enhanced by ink coating on substrate microfibers and metal embedding into the PDMS matrix. In addition, Cu on paper shows extremely low sheet resistance (0.29 mΩ/□), and Cu on nylon shows outstanding foldability with a resistance of less than five times of initial resistance during 5000 folding cycles.

Transcriptomic analysis of ovarian signaling at the emergence of the embryo from obligate diapause in the American mink (Neovison vison).

Mink embryonic diapause occurs when embryos, at the blastocyst stage, enter a state of a reversible arrest in development and metabolism. Some ovarian factors are required because ovariectomy leads to prevention of implantation in mink. Mechanisms regulating this process, however, remain largely unknown. To explore ovarian modifications associated with emergence of embryonic diapause in mink, there was comparison of transcriptomes after embryonic activation to when there was embryonic diapause using RNA-sequencing. A library of 655 differentially expressed genes (DEGs) of all assembled 33,656 genes was generated. Among these, 558 genes were annotated with 106 genes being expressed to a greater extent in ovaries during embryonic diapause, whereas 452 genes were more abundantly expressed in ovaries after embryonic activation. The major categories of genes with differential transcript abundances include metabolic pathways, metabolism of tryptophan, tyrosine and vitamin B6, oxidoreductase activity, calcium signaling pathway, steroid biosynthesis and lysosome. The APOE and APOA1 hub genes identified through the protein-protein interaction (PPI) analysis have important functions in cholesterol transport and steroidogenesis. Transcript abundances associated with 39 genes were investigated using RT-qPCR procedures to confirm RNA-sequencing data. Of 29 mRNA transcripts, 26 were validated using RNA-sequencing, whereas three of ten indistinguishable genes determined using RNA-sequencing were confirmed. Most of these verified DEGs are involved in the prolactin signaling pathway, formation of functional corpora lutea, and steroid synthesis, suggesting these biological processes are implicated in embryonic reactivation. Overall, results provide new insights into ovarian signaling at the time of emergence of the blastocyst from diapause in mink.

Recent Advanced on the MXene-Organic Hybrids: Design, Synthesis, and Their Applications.

With increasing research interest in the field of flexible electronics and wearable devices, intensive efforts have been paid to the development of novel inorganic-organic hybrid materials. As a newly developed two-dimensional (2D) material family, MXenes present many advantages compared with other 2D analogs, especially the variable surface terminal groups, thus the infinite possibility for the regulation of surface physicochemical properties. However, there is still less attention paid to the interfacial compatibility of the MXene-organic hybrids. To this end, this review will briefly summarize the recent progress on MXene-organic hybrids, offers a deeper understanding of the interaction and collaborative mechanism between the MXenes and organic component. After the discussion of the structure and surface characters of MXenes, strategies towards MXene-organic hybrids are introduced based on the interfacial interactions. Based on different application scenarios, the advantages of MXene-organic hybrids in constructing flexible devices are then discussed. The challenges and outlook on MXene-organic hybrids are also presented.