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The development of low-price and highly efficient catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has always been challenging with regard to water splitting. Pyrrhotite Fe7S8 has become a research hotspot due to its abundant reserves, high electrical conductivity and excellent catalytic activity. In general, introducing metal heteroatoms into transition metal sulfides (TMSs) can effectively enhance the activity and stability of TMSs. Herein, Co-doped pyrrhotite Fe7S8 nanosheets were obtained by a straightforward two-step method consisting of hydrothermal treatment followed by subsequent heat treatment. Results from XPS analysis and contact angle measurements showed that doping optimized the chemical environment around iron atoms and enhanced the adsorption of water molecules on the surface of Fe7S8, thereby greatly improving the electrocatalytic efficiency of water electrolysis. Compared with other counterparts, Co0·95Fe6·05S8 exhibited superior OER activity with an overpotential of 311 mV at a current density of 10 mA cm−2, and higher performance towards HER with an overpotential of 284 mV at 10 mA cm−2 in alkaline solution. In sum, Co0·95Fe6·05S8 is promising as a bifunctional catalyst for water splitting under alkaline conditions.

Nanoarchitecture materials are widely investigated to enhance hydrogen evolution reaction (HER) performance. However, it is beset with difficulties to obtain nanomaterials at industrial-scale in comparison with bulk materials. Herein, bulk electrocatalyst Fe4.5Ni4.5S8/Fe7S8 is prepared using flotation method and alkali cleaning from natural nickel ore. Sulfur vacancies and electron interaction between Fe7S8 and Fe4.5Ni4.5S8 may efficiently reduce hydrogen adsorption energy's absolute value, thus significantly improving hydrogen production efficiency. Hybrid catalyst requires ultralow overpotential of 48 mV at 10 mA cm−2 for HER in 0.5 M H2SO4 and exhibits high stability (maintaining an almost constant overpotential after 20,000 cyclic voltammetry sweeps). Therefore, it can be affirmed that it demonstrates promising industrial application as an electrocatalyst towards HER.

Ethylene-propylene rubber, linear low-density polyethylene and polyolefin elastomer, which are prepared by copolymerization of ethylene with α-olefins, have an important market share of the industry due to their excellent properties. Catalyst plays important role in the copolymerization of ethylene with α-olefins. Many vanadium complexes in the oxidation states of +3, +4 and +5 have been developed as precatalyst for the copolymerization. The progress of vanadium complex catalysts and their use in copolymerization of ethylene with α-olefins were reviewed. The effects of chelated ligands on the catalytic activity of catalysts, composition, molecular weight, molecular weight distribution and sequence of the resulting copolymers were discussed. Vanadium(III) complexes are widely used since vanadium(III) species are usually considered as active species in olefin coordination polymerization. Vanadium(III) complexes bearing monodentate N -heterocyclic carbene (NHC) ligand or bidentate β-diketonate ligands have been used as precatalyst in copolymerization of ethylene with propylene, affording ethylene-propylene copolymers with high propylene content. Ethylene-propylene copolymers with ultra-high molecular weight were prepared by using vanadium(III) complexes containing NHC ligand. Vanadium(III) complexes bearing chelated bidentate N^N or N^O, etc. ligands show high catalytic activity up to 8820 kg mol–1 h–1 toward copolymerization of ethylene with 1-hexene. The introduction of bulky substitutes on the ligand results in an increase in the reactive ratio of ethylene and a decrease in the reactive ratio of 1-hexene, and thus a change in the sequence of monomer in the resulting copolymer. Vanadium(III) complexes containing tridentate and tetradentate ligands display relatively lower catalytic activity than their analogues containing similar bidentate ligand. Most vanadium(IV) complexes display lower catalytic activity than vanadium(III) complexes bearing similar ligands. Ethylene-propylene copolymer with high propylene content could be prepared by copolymerization of ethylene and propylene catalyzed by vanadium(IV) complexes containing monodentate amide ligands. Vanadium(V) complexes bearing chelating aryloxides have been shown to be highly active (up to 144400 kg mol–1 h–1) in copolymerization of ethylene with propylene, affording ethylene-propylene copolymers with low propylene content (less than 15%(mol)). Ethylene-propylene copolymers with high propylene content (more than 30%(mol)) could be prepared by vanadium complexes containing monodentate or bedentate ligands. It is interesting to note that quasi-living copolymerization of ethylene with propylene was realized by using vanadium(V) complexes containing NHC ligand and ethylene-propylene copolymers with ultrahigh molecular weight and narrow molecular weight distribution were obtained. In conclusion, the vanadium complex catalysts have displayed good catalytic behavior towards the copolymerization of ethylene with α-olefins. The vanadium complexes discussed here may be an inspiration for future work in the development of vanadium complex catalyst with high catalytic activity and high comonomer incorporation for copolymerization of ethylene with α-olefins.

PD-1 immune checkpoint blockade and cytokine IL-33 have shown significant therapeutic effects in tumor immunotherapy. These therapies promote CD8+ T cell activation, proliferation, and effector functions. However, there were few research about the combined therapy efficacy. In this study, we established B16-empty vector and B16-IL33 melanoma mouse models and treated with PD-1 monoclonal antibody. We reported that PD-1 blockade combined with cytokine IL-33 further inhibited tumor progression and prolonged the survival of tumor-bearing mice. Mechanistically, the combination therapy was found to further facilitate CD4+ and CD8+ T lymphocytes accumulation, and enhance the antitumor effects of CD4+or CD8+tumor-infiltrating lymphocytes by promoting type-1 immune response within the tumor microenvironment using flow cytometry and quantitative real time polymerase chain reaction. Thus, PD-1 blockade combined with IL-33 has application potential in tumor immunotherapy. Further, this study provides a new promising strategy and theoretical basis for tumor combination immunotherapy.

Lamellar and hexagonal–coil–cylinder self-assembled structures of ABA type triblock copolymers containing mesogen-jacketed liquid crystalline polymer (MJLCP) as the rod block, and polyisobutylene (PIB) as the coil middle block were discovered. PIB was synthesized by living cationic polymerization of isobutylene initiated by 1,4-bis(2-chloro-2-propyl)benzene (p-DCC), and then a small amount of styrene was introduced at the end of the PIB chains to form the difunctional PIB macroinitiator with -CH2CH(C6H5)Cl end groups for further atom transfer radical polymerization (ATRP). 2,5-Bis[(4-methoxyphenyl)oxycarbonyl]styrene (MPCS) was block-copolymerized from the difunctional PIB macroinitiators at 110 °C. The molecular characterization of the triblock copolymers was performed with 1H NMR, 13C NMR, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Their phase structures and transitions were investigated by differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and polarized optical microscopy experiments. It was demonstrated that the triblock copolymers formed lamellar structures at moderate rod fractions and hexagonal coil cylinders in the rod matrix at high rod fractions. The d-spacing of the microphase-separated structures was influenced by the liquid crystalline phase of rod-like PMPCS blocks.

We performed dynamic Monte Carlo simulations of random copolymers containing variable sliding mobility of non-crystallizable comonomer sequences (reflecting their relative sizes) in the crystalline monomer regions. Upon raising strains, we observed that the comononer sliding mobility does not affect the strain evolution curves of crystallinity. However, in the middle temperature region, the low mobility causes a delay of switching from the intra-molecular to the inter-molecular modes of crystal nucleation in the copolymers holding low fractions of comonomers. We attributed the effect to the difficulty of comonomers to be excluded from the nucleating domains that are limited by sequence segregation in the oriented amorphous segments. The implication of this effect to the efficiency of crystal nucleation upon cyclic loading has been discussed.

Tumor-derived exosomes (TEXs) are extracellular vesicles that are continuously released into the blood by tumor cells and carry specific surface markers of the original tumor cells. Substantial evidence has implicated TEXs as attractive diagnostic markers for cancer. However, the detection of TEXs in blood at an early tumor stage is challenging due to their very low concentration. Here, we established a method called PLA-RPA-TMA assay that allows TEXs to be detected with high sensitivity and specificity. Based on two proximity ligation assay (PLA) probes that recognize a biomarker on a TEX, we generated a unique surrogate DNA signal for the specific biomarker, which was synchronously amplified twice by recombinase polymerase amplification (RPA) coupled with transcription-mediated amplification (TMA), and then the products of the RPA-TMA reaction were quantitatively detected using a gold nanoparticle-based colorimetric assay. We established proof-of-concept evidence for this approach using TEXs from nasopharyngeal carcinoma (NPC) cells, with a detection limit of 102 particles/mL, and reported the measurement of plasma Epstein-Barr virus latent membrane protein 1 (LPM1)-positive (LMP1+, accuracy: 0.956) and epidermal growth factor receptor (EGFR)-positive (EGFR+, accuracy: 0.906) TEXs as potent early diagnostic biomarkers for NPC.

We developed a linear combination of two Flory’s melting-point theories, one for stretched and the other for solution polymers, to predict the melting point of stretched solution polymers. The dependences of the melting strains on varying temperatures, polymer volume fractions, and solvent qualities were verified by the onset strains of crystallization in our dynamic Monte Carlo simulations of stretched solution polymers under a constant strain rate. In addition, owing to phase separation before crystallization in a poor solvent, calibration of polymer concentration to the polymer-rich phase appears necessary for the verification. Our results set up a preliminary thermodynamic background for the investigation of the multicomponent effect on strain-induced crystallization of polymers in rubbers and gels as well as on shear-induced crystallization of polymers in solutions and blends.

The cationic grafting polymerization of isobutylene (IB) from a poly(vinyl acetate) (PVAc) backbone was initiated by the combination of PVAc with titanium tetrachloride (TiCl4) in methylene chloride (CH2Cl2) solution at –65°C. A mixture of IB homopolymer and PVAc grafted with approximately 9.5% (mol) PIB copolymer was formed. 1H- and 13C-NMR spectra confirmed that IB was successfully grafted from the PVAc backbone. PVAc exhibits both initiation and modification behavior. PVAc acts as a macro-initiator in the polymerization to form the graft copolymer. It also plays a role in the homopolymerization of IB initiated by the combination of residual water with TiCl4 and the product PIB with a narrow molecular weight distribution.

The cationic polymerization of isobutylene coinitiated by Al(i-Bu)Cl2(Al) was carried out in mixed butane–butene fractions at −50 °C. The expected polymerization processes induced by the trace of moisture with Al system in the presence of a small amount of external electron-donor modifiers, such as methyl acrylate (MA) and dimethyl sulfoxide (DMSO), were obtained. The experimental results showed that these polymerizations produced polymers with relatively high number-average molecular weights and narrow molecular weight distributions (1.5–2.2). That the gel permeation chromatography traces of the polymers depended on the types and concentrations of external donors suggested that there existed competitive complexation reactions of various electron donors (H2O, MA, and DMSO) with the Al Lewis acid. The roles of external electron donors were to take part in the initiation step by competitive complexation and to modify the reactivity of the growing chain ends in the propagation step by mediation and/or solvation, which impaired the high reactivity of the original growing chain ends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2209–2214, 2002

The cationic polymerizations of isobutylene (IB) initiated by the H2O/TiCl4 in dichloromethane (CH2Cl2) at −30 °C were carried out in the absence and presence of various external electron pair dono...

Industrial semi-crystalline polymers contain various kinds of sequence defects, which behave like non-crystallizable comonomer units on random copolymers. We performed dynamic Monte Carlo simulations of strain-induced crystallization of random copolymers with various contents of comonomers at high temperatures. We observed that the onset strains of crystallization shift up with the increase of comonomer contents and temperatures. The behaviors can be predicted well by a combination of Flory's theories on the melting-point shifting-down of random copolymers and on the melting-point shifting-up of strain-induced crystallization. Our thermodynamic results are fundamentally important for us to understand the rubber strain-hardening, the plastic molding, the film stretching as well as the fiber spinning.