Effects of the Imbibition Ability of Extinguishant in Pulverized Coals

The imbibition ability of extinguishant is an important factor influencing the extinguishing effect for smoldering fire in pulverized coals. The coal particle size, bulk compactness, and aqueous solution properties significantly affect the imbibition ability of extinguishment. This work aims to reveal the influence of the properties of pulverized coals and aqueous solution on the imbibition ability of extinguishant for smoldering fire through experiments and capillary theories. The imbibition height and rate were adopted to evaluate the imbibition ability of extinguishment. The results showed that a relatively small bulk compactness and a fine coal particle size negatively influenced the extinguishing process dominantly because of its high surface energy and low wettability. An additive was used to adjust the properties of aqueous solution. The liquid with a larger surface tension, a smaller contact angle, and a lower viscosity induced a better imbibition ability of extinguishment.

Melatonin inhibits the expression of vascular endothelial growth factor in pancreatic cancer cells

Objective： To investigate the effects of melatonin on cellular proliferation and endogenous vascular endothelial growth factor （VEGF） expression in pancreatic carcinoma cells （PANC-1）. Methods： PANC-1 cells were cultured for this study. The secreted VEGF concentration in the culture medium was determined using ELISA method, VEGF production in the tumor cells was detected by immunocytochemistry, and VEGF mRNA expression was determined by RT-PCR. Results： Higher melatonin concentrations significantly inhibited cellular proliferation, with 1 mmol/ L concentration exhibiting the highest inhibitory effect （P〈0.01）. VEGF concentrations in the cell culture supernatants and intra-cellules were all significantly reduced after melatonin （1 retool/L） incubation （P〈0.05）. VEGF mRNA expression decreased markedly in a time-dependent manner during the observation period （P〈0.05）. Conclusions： High melatonin concentrations markedly inhibited the proliferation of pancreatic carcinoma cells. The endogenous VEGF expression was also suppressed by melatonin incubation.

初心和使命:《共产党》月刊的历史意义

在不同历史时期,中国共产党人初心和使命有着不同的历史内涵。“为人民谋幸福,为民族谋复兴”的初心和使命在建党时期的内涵包括:选择一条什么样的道路,建立什么样性质的政党,具体如何建党。《共产党》月刊的创刊背景与共产党的创立背景一致,那就是建立马克思主义政党,《共产党》月刊的刊物内容则从俄国模式、信仰依据、组织建构等方面回答了如何建党,即初心和使命如何践行的问题,这些也对当代中国建设给出了借鉴的思路,这是《共产党》月刊的历史意义。

Single droplet formation by controlling the viscoelasticity of polymer solutions during inkjet printing

Inkjet printing has emerged as a potential solution processing method for large-area patterned films.During inkjet printing,a single droplet without satellite droplet is required for high-quality film.Herein,we propose a strategy for obtaining a single droplet by adjusting the reduced concentration(c/c^(*),where c^(*)is the critical overlap concentration)in the range of 1.0-1.5.Droplet formation can be categorized into three distinct regimes:(1)c/c^(*)<1.0,satellite droplet;(2)c/c^(*)=1.0-1.5,single droplet;(3)c/c^(*)>2.0,no droplet.Furthermore,an inertial-capillary balance led to the 2/3-power scaling of the minimum radius with time for the solutions of c/c^(*)<1.0.However,for the solutions of c/c^(*)=1.0-1.5,the ligament radius decreased exponentially with time.Moreover,the Weissenberg number was higher than the critical value of 0.5,indicating that the polymer chains underwent coil-stretch transition.The viscoelastic-capillary balance dominated instead of the inertial-capillary balance.The resulting viscoelastic resistance reduced the length of the ligament and increased the velocity difference between the satellite and main droplets.Consequently,a single droplet was formed.In addition,the law can be successfully generalized to various molecular weights,molecular structures and solvents.

Aggregate Engineering in Supramolecular Polymers via Extensive Non-covalent Networks

Aggregate engineering of non-covalent networks endows supramolecular polymers with thermo-mechanical versatility,stimuli-responsive phase transitions and intrinsic damage-healing capabilities.However,most non-covalent networks are vulnerable at elevated temperatures,which suppresses the robustness of supramolecular polymers.Herein,ureidocytosine(UCy)motifs,which are capable of forming extensive non-covalent networks and thus robust molecular aggregates via multivalent hydrogen bonds and aromatic stackings,are proposed to enable precise programming of the thermo-mechanical versatility.Molecular simulations reveal that the enthalpic contributions from the UCy aggregates play dominant roles to compensate the entropic loss from the redistributions of polymeric spacers and stabilize the non-covalent networks over wide temperature windows.Such aggregate-level strategy offers prospects for applications which require thermo-mechanical versatility of supramolecular polymers,such as 3D printing,microfabrication and damage-healing coating.

Bio‐inspired spontaneous splitting of underwater bubbles along a superhydrophobic open pathway without perturbation

Bubbles are pervasive in aqueous media,and on account of numerous advantages of tiny bubbles,efficient bubble splitting is favorable in a wide range of applications.However,underwater bubble splitting faces a lot of challenges because bubbles tend to coalesce during the rising due to the action of buoyancy and surface energy,and the consumption of considerable external energy is needed.Inspired by the bubble bursting phenomenon on the feathers of high‐speed swimming penguins,we proposed a new bubble splitting strategy based on the energy conversion of bubble transportation on superhydrophobic open pathways.A porous superhydrophobic coating was first developed via a bubbletemplate assisted fabrication method,which provides hierarchical micro/nanostructures and robust air plastron.Gas bubbles can transport along the superhydrophobic open pathways without perturbation,and split into smaller ones by taking advantage of the potential energy contributed by buoyancy.By controlling the superhydrophobic pathway,the size of the split bubbles can be controlled precisely.We also demonstrated that a bubble splitting device could be applied in underwater reactions where an enhanced gas−liquid mass transfer is desired.This bubble splitting strategy may offer new prospects for underwater bubble manipulation and unfold a potential in many bubble‐involved fields.