Highly Durable Silicone-Based Elastomers Achieved Through the Synergy of Bi-Incompatible Soft Segments and Multi-Scale Hydrogen Bonds.

Developing a silicone elastomer with high strength, exceptional toughness, good crack tolerance, healability, and recyclability, poses significant challenges due to the inherent trade-offs between these properties. Herein, the design of silicone-based elastomers with a nanoscopic microphase separation structure and comprehensive mechanical properties is achieved by combining bi-incompatible soft segments and multi-scale hydrogen bonds. The formation of multi-scale hydrogen bonds involving urethane, urea, and 2-ureido-4[1H]-pyrimidinone (UPy) facilitates efficient reversible crosslinking of the synthesized polymer containing thermodynamically incompatible poly(dimethylsiloxane) (PDMS) and poly(propylene glycol) (PPG). The dynamic dissociation and recombination of hydrogen bonds, coupled with the forced compatibility and spontaneous separation of bi-incompatible soft segments, can effectively dissipate energy, particularly in the crack region during the stretching process. The obtained silicone-based elastomer exhibits a high break strength of 8.0 MPa, good elongation at break of 1910%, ultrahigh toughness of 67.8 MJ m-3, and unprecedented fracture energy of 31.8 kJ m-2 while maintaining their thermal stability, hydrophobicity, healability, and recyclability. This resilient and long-lasting silicone-based elastomer exhibits significant potential for use in flexible electronic devices.

Nano-mechanical characterization of disassembling amyloid fibrils using the Peak Force QNM method.

The comprehensive understanding of disassembly mechanism of amyloid fibrils requires nano-scale characterization of the mechanical properties of amyloid fibrils during the disassembly process. In this work, gemini surfactant C12 C6 C12 Br2 micelles were used as a probe to disassemble Aß(1-40) fibrils. The microstructure evolution and nano-mechanical properties of Aß(1-40) fibrils during the disassembly process were systematically investigated by the Peak Force Quantitative Nano-mechanical (PF-QNM) technique. The results show an obvious decrease in Young's modulus of mature fibrils with high ß-sheet contents (2.4 ± 1.0 GPa) in comparison to the resulting peptide/surfactant complexes (1.1 ± 0.8 GPa) with loose surface structures. Interestingly, the Young's modulus of spherical peptide/surfactant complexes on the core was more than 3 GPa. This strategy can be used as a standard protocol to investigate the interaction mechanism between amyloid fibrils and small molecules, which may open up new possibilities to explore the mechanism of relevant human diseases.

Co-assembly of donor and acceptor towards organogels tuned by charge transfer interaction strength.

Co-assembly of n-type semiconductors NDI and PDI with p-type pyrene derivatives resulted in the formation of stable organogels, which was induced by the strong charge transfer (CT) interactions between acceptors and donors in chloroform. The dimension size of the aromatic core from the acceptors was found to have a significant impact on the organogels. The width of the fibers from CT gels with NDI is about twice that from gels with PDI. It was found that the acceptor NDI preferred an alternate stacking with donors, intercalated with each other via CT interactions. In contrast, the acceptor PDI preferred to stack among themselves within the assemblies and this arose from the stronger π-π interactions because they had larger aromatic cores than the acceptor NDI. The dimension size of the aromatic core has been proved to have a significant impact on the organogels. The substituent impact of the donors was also studied.

Fibroblast growth factor (Fgf) signaling pathway regulates liver homeostasis in zebrafish.

In mammals, fibroblast growth factor (FGF) signaling controls liver specification and regulates the metabolism of lipids, cholesterol, and bile acids. FGF signaling also promotes hepatocyte proliferation, and helps detoxify hepatotoxin during liver regeneration after partial hepatectomy. However, the function of Fgf in zebrafish liver is not yet well understood, specifically for postnatal homeostasis. The current study analyzed the expression of fgf receptors (fgfrs) in the liver of zebrafish. We then investigated the function of Fgf signaling in the zebrafish liver by expressing a dominant-negative Fgf receptor in hepatocytes (lfabp:dnfgfr1-egfp, lf:dnfr). Histological analysis showed that our genetic intervention resulted in a small liver size with defected medial expansion of developing livers in transgenic (Tg) larvae. Morphologically, the liver lobe of lf:dnfr adult fish was shorter than that of control. Ballooning degeneration of hepatocytes was observed in fish as young as 3 months. Further examination revealed the development of hepatic steatosis and cholestasis. In adult Tg fish, we unexpectedly observed increased liver-to-body-weight ratios, with higher percentages of proliferating hepatocytes. Considering all these findings, we concluded that as in mammals, in adult zebrafish the metabolism of lipid and bile acids in the liver are regulated by Fgf signaling. Disruption of the Fgf signal-mediated metabolism might indirectly affect hepatocyte proliferation.

Fabrication of Ru/WO3-W2N/N-doped carbon sheets for hydrogen evolution reaction.

Recent experimental analysis indicates WO3-based nanostructures exhibit poor hydrogen evolution reactivity, particularly in alkaline medium, arising from the low electron transfer rate. It is imperative to tune the composition and structure of WO3 to boost the cleavage of H-OH bond. Here, we construct Ru/WO3-W2N/N-doped carbon sheets (Ru/WO3-W2N/NC) using m-WO3 nanosheets as precursors with the aid of RuCl3, Tris (hydroxymethyl) aminomethane, and dopamine. Structural investigation reveals the formation of N-doped carbon sheets, Ru nanoparticles, and WO3-W2N. As a result, hydrogen evolution reactivity is greatly improved on Ru/WO3-W2N/N-doped carbon sheets with 64 mV at 10 mA/cm2 in 1 mol/L (M) KOH, outperforming most of WO3-based electrocatalysts in previous literatures. Meanwhile, it facilitates the generation of H2 in 0.5 M H2SO4 with the excellent activity of 110 mV at 10 mA/cm2. Our work provides an efficient strategy to tailor the electronic structure of WO3 to catalyze acidic and alkaline hydrogen evolution reaction.

Engineering P-Fe2O3-CoP nanosheets for overall freshwater and seawater splitting.

Tailoring surface composition and coordinative environment of catalysts in a nano-meter region often influence their chemical performance. It is reported that CoP exhibits a low dissociation ability of H-OH, originating from the poor desorption of intermediate species. Herein, we provide a feasible method to construct P-Fe2O3-CoP nanosheets through a gas-phase phosphorization process. P doping induces the formation of interfacial structure between Fe2O3 and CoP and the generation of defective structures. The resulting P-Fe2O3-CoP nanosheets afford high freshwater/seawater oxidation activity (250/270 mV@10 mA/cm2) in 1 mol/L (M) KOH, which is even lower than commercial RuO2. Compared with CoP||CoP, P-Fe2O3||P-Fe2O3, and Co3O4||Co3O4, the assembled P-Fe2O3-CoP||P-Fe2O3-CoP exhibits the superior water/seawater electrolysis performance with 1.61/1.65 V@10 mA/cm2. The synergistic effect of P doping, defective structure, and heterojunction leads to high water oxidation efficiency and water splitting efficiency.

N-doped carbon sheets supported P-Fe3O4-MoO2 for freshwater and seawater electrolysis.

Electric-driven freshwater/seawater splitting is an attractive and sustainable route to realize the generation of H2 and O2. Molybdenum-based oxides exhibit poor activity toward freshwater/seawater electrolysis. Herein, we adjusted the electronic structure of MoO2 by constructing N-doped carbon sheets supported P-Fe3O4-MoO2 nanosheets (P-Fe3O4-MoO2/NC). P-Fe3O4-MoO2/N-doped carbon sheets were precisely prepared by pyrolysis of Schiff base Fe complex and MoO3 nanosheets through phosphorization. Benefiting from the unique structures of the samples, it required 119/145 mV to drive freshwater/seawater reduction reaction at 10 mA/cm2. P-Fe3O4-MoO2/NC catalysts exhibited superior freshwater/seawater oxidation reactivity with 180/189 mV at 10 mA/cm2 compared with commercial RuO2. The low cell voltages for P-Fe3O4-MoO2/NC were 1.47 and 1.59 V towards freshwater and seawater electrolysis, respectively. Our work might shed light on the structural modulation of Mo-based oxides for enhancing freshwater and seawater electrolysis activity.

Expression and function of fibroblast growth factor (FGF) 7 during liver regeneration.

BACKGROUND/AIM: Previous studies have shown that fibroblast growth factors (FGFs) are involved in the process of liver injury repair. Liver regeneration after partial hepatectomy (PH) is impaired in transgenic mice expressing dominant-negative FGFR2b in hepatocytes. Although FGF7, a ligand specifically bound to FGFR2b, is expressed by activated hepatic stellate cells (HSCs) in fibrotic livers, the expressions and functions of FGF7 and FGFR2b after PH remain unexplored. Therefore, this study sought to examine the potential role of FGF7 signaling during liver regeneration. METHODS: We examined the expression of FGF7 and FGFR2b in normal and regenerating livers. Effects of FGF7 on hepatocytes were examined in vitro using primary hepatocyte culture with FGF7 recombinant protein and in vivo by hydrodynamic-based gene transfer method. RESULTS: We found that FGF7 expression was increased according to the activation status of HSCs after PH. The receptor, FGFR2b, was also increased in hepatocytes during liver regeneration. In vitro treatment with FGF7 protein activated ERK1/2 and promoted proliferation of hepatocytes isolated from regenerating livers. In vivo overexpression of exogenous FGF7 could notably promote hepatic proliferation and activate MAPKs after PH. CONCLUSION: This study suggests a role for activated HSC-expressed FGF7 in stimulating FGF signaling pathways in hepatocytes and regulating liver regeneration.

Enhanced oxygen and hydrogen evolution performance by carbon-coated CoS2-FeS2 nanosheets.

It is vital to tailor the surface structure and composition of nanocatalysts, which greatly affect the catalytic activity through the exposure of specific atom coordination environment. To date, less progress has been made in tuning the interface structures of pyrite for promoting the catalytic activity towards overall water splitting. Herein, we developed a facile one-spot strategy to make carbon-layer-coated CoS2-FeS2 heterojunction nanosheets. The carbon layer and interface structures between Co-S and Fe-S were characterized via high resolution transmission electron microscopy. It exhibited a high OER activity with 1.47 V at 10 mA cm-2, which was superior to that of the commercial RuO2. Meanwhile, the carbon-layer-coated CoS2-FeS2 heterojunction nanosheets with the overpotential of 210 mV at 10 mA cm-2 was more active than FeS2 nanosheets with 240 mV in the hydrogen evolution reaction. Notably, it enhanced the catalytic activity towards the overall water splitting with the voltage of 1.66 V at 10 mA cm-2 using a two-electrode system. The remarkable long-term stability was verified by a slight change in the current density of 6 mA cm-2 for 26 h. The prominent catalytic activity could be related to the exposure of the carbon layer and interface structures. This work demonstrates that engineering the interface structure is essential for boosting the overall water splitting activity.

Vanadocene dichloride inhibits cell proliferation by targeting Aurora B.

Vanadocene dichloride (VDC) was shown to exhibit antitumor properties against a wide spectrum of tumor cell lines. Many studies have been carried out to reveal the bioactivities of VDC and the interaction mechanism of VDC with biological molecules in test tubes. One of the bioactivities of VDC is to arrest the cell cycle at the G2/M phase. However, its underlying mechanisms of action and cytotoxicity profile are still not fully understood. HeLa cells were used in this study, and the IC50 value of VDC was 8.61 µM after a 24-hour treatment. We used an immunofluorescence staining method to analyze the morphology of cells in the mitosis stage to elucidate what defects caused cell arrest in mitosis. Chromosomal misalignment was found to be the major phenotype. One of the proteins responsible for chromosome alignment at the metaphase is Aurora B kinase. Results of immunoblotting assay showed that Aurora B kinase activity was inhibited by VDC treatment. More than 50% of the Aurora B activity was inhibited when cells were treated with VDC at a concentration of 6.25 µM. That VDC was able to induce defects in chromosomal alignment at the metaphase by inhibiting the activity of Aurora B kinase is an important mechanism of VDC to be developed as an antitumor agent.

Pyrite FeS2/C nanoparticles as an efficient bi-functional catalyst for overall water splitting.

Exploration and fabrication of low-cost but highly active electrocatalysts, alternatives to noble metals, have remained a challenge for overall water splitting reaction. To date, few studies have reported that the Earth-abundant pyrite FeS2 is catalytically active for hydrogen evolution reaction, while there is no study on the oxygen evolution reaction and overall water splitting reaction using pyrite FeS2 as an electrocatalyst. Here, we offer a facile hydrothermal approach for the synthesis of FeS2 nanoparticles by the reduction of FeCl3·6H2O with C5H10NS2Na·3H2O. The FeS2/C nanoparticles on Ni foam (NF) deliver 10 mA cm-2 at an overpotential of 240 mV towards the oxygen evolution reaction, which is lower than that of IrO2. It requires 202 mV to drive the hydrogen evolution reaction to reach 10 mA cm-2, while long-term durability and faster charge-transfer kinetics confirm the good hydrogen evolution reaction performance on FeS2/C/Ni foam. Moreover, the pyrite FeS2/C/nanoparticles on Ni foam are assembled as an anode and cathode in a two-electrode alkaline electrolyzer and show good overall water splitting efficiency with 1.72 V at 10 mA cm-2.

Two-Dimensional Crystallization of Rylene Diimide Based n-Type Semiconductors Tuned by the Dimensions of the Aromatic Core at the Liquid-Solid Interface.

The investigation of semiconductors at the surface provides opportunities to observe and understand the mechanism of molecular interaction for the design of semiconductors so that organic electronics with good performance can be built. Herein, the 2D crystallization of rylene diimide based n-type semiconductors (i.e., 1-4) was explored at the liquid-highly oriented pyrolytic graphite interface by means of scanning tunneling microscopy. Rylene diimides 1-3 with increased aromatic dimensions show different surface crystallization behaviors and distinguished 2D patterns. The surface chirality was also found to be directly affected by the aromatic dimensions. The 2D patterns and the surface chirality could also be tuned by the nature of the solvent. In addition, molecular symmetry was found to be of great important for the formation of long-range ordered 2D monolayers. This investigation highlights the importance of the rational design of molecular dimensions and geometrical symmetry in achieving determined 2D nanopatterns on surfaces, especially for the rylene diimide based n-type semiconductors.

Zebrafish: A Premier Vertebrate Model for Biomedical Research in Indian Scenario.

The zebrafish (Danio rerio) is a versatile model organism that has been used in biomedical research for several decades to study a wide range of biological phenomena. There are many technical advantages of using zebrafish over other vertebrate models. They are readily available, hardy, easy, and inexpensive to maintain in the laboratory, have a short life cycle, and have excellent fecundity. Due to its optical clarity and reproducible capabilities, it has become one of the predominant models of human genetic diseases. Zebrafish research has made rapid strides in the United States and Europe, but in India the field is at an early stage and many researchers still remain unaware of the full research potential of this tiny fish. The zebrafish model system was introduced into India in the early 2000s. Up to now, more than 200 scientific referred articles have been published by Indian researchers. This review gives an overview of the current state of knowledge for zebrafish research in India, with the aim of promoting wider utilization of zebrafish for high level biological studies.

Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV).

Fibroblast growth factor receptor 2c signaling is required for intestinal cell differentiation in zebrafish.

BACKGROUND: There are four cell lineages derived from intestinal stem cells that are located at the crypt and villus in the mammalian intestine the non-secretory absorptive enterocytes, and the secretory cells, which include mucous-secreting goblet cells, regulatory peptide-secreting enteroendocrine cells and antimicrobial peptide-secreting Paneth cells. Although fibroblast growth factor (Fgf) signaling is important for cell proliferation and differentiation in various tissues, its role in intestinal differentiation is less well understood. METHODOLOGY/PRINCIPAL FINDINGS: We used a loss of function approach to investigate the importance of Fgf signaling in intestinal cell differentiation in zebrafish; abnormal differentiation of goblet cells was observed when Fgf signaling was inhibited using SU5402 or in the Tg(hsp70ldnfgfr1-EGFP) transgenic line. We identified Fgfr2c as an important receptor for cell differentiation. The number of goblet cells and enteroendocrine cells was reduced in fgfr2c morphants. In addition to secretory cells, enterocyte differentiation was also disrupted in fgfr2c morphants. Furthermore, proliferating cells were increased in the morphants. Interestingly, the loss of fgfr2c expression repressed secretory cell differentiation and increased cell proliferation in the mib(ta52b) mutant that had defective Notch signaling. CONCLUSIONS/SIGNIFICANCE: In conclusion, we found that Fgfr2c signaling derived from mesenchymal cells is important for regulating the differentiation of zebrafish intestine epithelial cells by promoting cell cycle exit. The results of Fgfr2c knockdown in mib(ta52b) mutants indicated that Fgfr2c signaling is required for intestinal cell differentiation. These findings provide new evidences that Fgf signaling is required for the differentiation of intestinal cells in the zebrafish developing gut.

A variant of fibroblast growth factor receptor 2 (Fgfr2) regulates left-right asymmetry in zebrafish.

Many organs in vertebrates are left-right asymmetrical located. For example, liver is at the right side and stomach is at the left side in human. Fibroblast growth factor (Fgf) signaling is important for left-right asymmetry. To investigate the roles of Fgfr2 signaling in zebrafish left-right asymmetry, we used splicing blocking morpholinos to specifically block the splicing of fgfr2b and fgfr2c variants, respectively. We found that the relative position of the liver and the pancreas were disrupted in fgfr2c morphants. Furthermore, the left-right asymmetry of the heart became random. Expression pattern of the laterality controlling genes, spaw and pitx2c, also became random in the morphants. Furthermore, lefty1 was not expressed in the posterior notochord, indicating that the molecular midline barrier had been disrupted. It was also not expressed in the brain diencephalon. Kupffer's vesicle (KV) size became smaller in fgfr2c morphants. Furthermore, KV cilia were shorter in fgfr2c morphants. We conclude that the fgfr2c isoform plays an important role in the left-right asymmetry during zebrafish development.