Installing a Trigger to Upcycle High-Density Polyethylene.

Creating C═C bonds as "weak" sites in the stable C-C chains of polyethylene (PE) is an appealing strategy to promote sustainable development of the polyolefin industry. Compared to methods, such as dehydrogenation and postpolymerization modification, the copolymerization of ethylene (E) and butadiene (BD) should be a convenient and direct approach to introduce C═C bonds in PE, whereas it encounters problems in controlling the composition and regularity of the copolymer due to the mismatched activities and mechanisms between the two monomers. Herein, we report by employing the amidinate gadolinium complex, controllable E/BD copolymerization was achieved, where BD was incorporated in the uniformly discrete 1,4 mode. The obtained copolymer possesses the same physical, mechanical, processing, and antioxygen (aging at 100 °C for 28 days) properties as commercial high-density-PE, which, strikingly, were degraded by C═C bonds into α,ω-telechelic oligomers with narrow distribution. These degraded functional products were transferred to compatibilizers via atom-transfer radical polymerization or immortal ring-opening polymerization, achieving upcycling.

Flexible porous organic polymers constructed using C(sp3)-C(sp3) coupling reactions and their high methane-storage capacity.

Carbon-carbon coupling is a basic design principle for the synthesis of porous organic polymers, which are widely used in gas adsorption/separation, photocatalysis, energy storage, etc. However, the C(sp3)-C(sp3) coupling reaction to construct porous organic polymers remains an important yet elusive objective due to its low reactivity and unknown side reactions. Herein, we report that nickel bis(1,5-cyclooctadiene) (Ni(COD)2), which was a famous catalyst for C(sp2)-C(sp2) coupling reactions, enables highly efficient C(sp3)-C(sp3) homo-coupling reactions to construct porous linear crystalline polymers and flexible three-dimensional porous aromatic frameworks (PAFs) under mild reaction conditions. The resulting linear polymers generated with dibromomethyl arenes have good crystallinity and high melting points (T m = 286 °C) due to controllability of reaction sites. Furthermore, the PAFs (PAF-64, PAF-65 and PAF-66) stemmed from tri-/tetra-bromomethyl arenes show high surface area (S BET = 390 m2 g-1) and high methane-storage capacity (up to 313 cm3 cm-3) because of their flexible frameworks. This work sheds new light on the construction of novel porous polymers through C(sp3)-C(sp3) coupling reactions and the development of methane-storage materials.

FAM198B promotes colorectal cancer progression by regulating the polarization of tumor-associated macrophages via the SMAD2 signaling pathway.

Colorectal cancer (CRC) is one of the most common malignant tumors. Tumor-associated macrophages (TAMs) promote the progression of CRC, but the mechanism is not completely clear. The present study aimed to reveal the expression and function of FAM198B in TAMs, and the role of FAM198B in mediating macrophage polarization in CRC. The role of FAM198B in macrophage activity, cell cycle, and angiogenesis was evaluated by CCK-8 assay, flow cytometry, and vasculogenic mimicry assay. The effects of FAM198B on macrophage polarization were determined by flow cytometry. The function of FAM198B-mediated macrophage polarization on CRC progression was evaluated by transwell assays. Bioinformatic analyses and rescue assays were performed to identify biological functions and signaling pathways involved in FAM198B regulation of macrophage polarization. Increased FAM198B expression in TAMs is negatively associated with poor CRC prognosis. Functional assays showed that FAM198B promotes M2 macrophage polarization, which leads to CRC cell proliferation, migration, and invasion. Mechanistically, FAM198B regulates the M2 polarization of macrophages by targeting SMAD2, identifying the SMAD2 pathway as a mechanism by which FAM198B promotes CRC progression through regulating macrophage polarization. These findings provide a possible molecular mechanism for FAM198B in TAMs in CRC and suggest that FAM198B may be a novel therapeutic target in CRC.

A Facile Approach to Produce Star Polymers Based on Coordination Polymerization.

Many efforts have been devoted to preparing star polymers. Research into coordination polymerization, the most powerful stereoselective process to endow polymers with superb properties, lags far behind those achieved by radical polymerization and ionic polymerization. Herein, we propose a facile strategy to prepare star polymers with regular arms based on coordination polymerization via an insertion reaction between the carbon-heteroatom unsaturated bond and the metal-alkyl species. Terminating a living cis-1,4-selective isoprene polymerization by using isocyanate as cross-linker (CL), a star polyisoprene with low polydispersity was obtained in high yield (91.8 %). A kinetic study showed the star polymer was formed via a step-growth procedure. The types of CL and the ratio of [CL]0 : [Cat.]0 are key factors to determine the arm number and the yield of star polymer. Finally, synthetic IR rubber with a green strength up to 1.99 MPa superior to natural rubber (1.43 MPa) was prepared for the first time.

MiR-25 enhances autophagy and promotes sorafenib resistance of hepatocellular carcinoma via targeting FBXW7.

Sorafenib resistance is a major challenge in the treatment of patients with advanced hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are a large family of non-coding RNA molecules, which is an important mechanism of drug resistance. We previously found that knockdown of miR-25 increased the sensitivity of TRAIL-induced apoptosis in liver cancer stem cells. We aimed to study the effects of miR-25 on sorafenib resistance of HCC and the underlying mechanisms. In the present study, we analyzed the expression of miR-25 between HCC and normal tissues and predicted miR-25 target genes through databases. After transfecting miR-25 mimics, inhibitor or FBXW7 Plasmid, CCK-8 and flow cytometry assay was performed to determine the sorafenib resistance. We performed LC3-dual-fluorescence assay and Western blotting to detect the autophagy levels. The expression of miR-25 was upregulated in human HCC tissues and was associated with tumor pathological grade, clinic staging, and lymphatic metastasis. MiR-25 enhanced sorafenib resistance of HCC cells and autophagy. FBXW7 is the direct target of miR-25. Overexpression of FBXW7 could reverse the increase of sorafenib resistance caused by miR-25 mimics. Our results suggested that miR-25 increased the sorafenib resistance of HCC via inducing autophagy. In addition, miR-25 decreases the expression of FBXW7 protein to regulate autophagy. Therefore, miR-25 may represent a novel therapeutic target for the treatment of HCC.

Accelerating Faceting Wide-Field Imaging Algorithm with FPGA for SKA Radio Telescope as a Vast Sensor Array.

The SKA (Square Kilometer Array) radio telescope will become the most sensitive telescope by correlating a huge number of antenna nodes to form a vast array of sensors in a region over one hundred kilometers. Faceting, the wide-field imaging algorithm, is a novel approach towards solving image construction from sensing data where earth surface curves cannot be ignored. However, the traditional processor of cloud computing, even if the most sophisticated supercomputer is used, cannot meet the extremely high computation performance requirement. In this paper, we propose the design and implementation of high-efficiency FPGA (Field Programmable Gate Array) -based hardware acceleration of the key algorithm, faceting in SKA by focusing on phase rotation and gridding, which are the most time-consuming phases in the faceting algorithm. Through the analysis of algorithm behavior and bottleneck, we design and optimize the memory architecture and computing logic of the FPGA-based accelerator. The simulation and tests on FPGA are done to confirm the acceleration result of our design and it is shown that the acceleration performance we achieved on phase rotation is 20× the result of the previous work. We then further designed and optimized an efficient microstructure of loop unrolling and pipeline for the gridding accelerator, and the designed system simulation was done to confirm the performance of our structure. The result shows that the acceleration ratio is 5.48 compared to the result tested on software in gridding parts. Hence, our approach enables efficient acceleration of the faceting algorithm on FPGAs with high performance to meet the computational constraints of SKA as a representative vast sensor array.

Optical bistablility in six-wave mixing parametrical amplification.

We investigate the nonreciprocity "∞"-shape optical bistability (OB) induced by the feedback dressing effect of six-wave mixing parametrically amplified process in a four-level atomic system. Compared to the traditional OB by scanning power, the "∞"-shape OB is scanning probe frequency and demonstrated by "∞"-shape non-overlapping region. More, this non-overlapping region in the x direction (frequency difference) and in the y direction (intensity difference) could demonstrate the degree of this OB phenomenon of dressed probe and conjugate signals, which can be changed by the intensity of feedback dressing. Further, we find the feedback intensity can be controlled by experimental parameters include powers of external-dressing, frequency detuning, incident phase and the nonlinear phase shift of internal-dressing beam. As a result, the nonreciprocity "∞"-shape OB is more sensitive and multiple than traditional OB. These outcomes have potential applications in logic-gate devices and quantum information processing.