A micro-crosslinked amphoteric hydrophobic association copolymer as high temperature-and salt-resistance fluid loss reducer for water-based drilling fluids

During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.

The Current Situation and Development of Grain Storage Technologies and Facilities for Chinese Farmers

In China, the quantity of farmer＇s grain storage covers about 40% of the total grain yield every year. While, the losses of farms＇ grain storage are up to 8%, which is due to the lack of grain storage facility and technology. The losses of farmer＇s grain storage could reach nearly 20 million tons every year. In this paper, the current situation and development of grain storage technology and facility for Chinese farmers were presented. And a series of policy and research work for reducing the losses of farms＇ grain storage was introduced. The large scale farmers are now developing quickly in China, the new storage warehouse and mechanized facility should be developed adaptively. So, the new storage technology and policy to meet the need of large scale farmers were also introduced in this paper.

Non-fullerene acceptors with heteroatom substitution on the core moiety for efficient organic photovoltaics

Organic photovoltaics(OPVs)represent one of the most promising photovoltaic technologies owing to their high capacity to convert solar energy to electricity.With the continuous structure upgradation of photovoltaic materials,especially that of non-fullerene acceptors(NFAs),the OPV field has witnessed rapid progress with power conversion efficiency(PCE)exceeding 19%.However,it remains challenging to overcome the intrinsic trade-off between the photocurrent and photovoltage,restricting the further promotion of the OPV efficiency.In this regard,it is urgent to further tailor the structure of NFAs to broaden their absorption spectra while mitigating the energy loss of relevant devices concomitantly.Heteroatom substitution on the fused-ringπ-core of NFAs is an efficient way to achieve this goal.In addition to improve the nearinfrared light harvest by strengthening the intramolecular charge transfer,it can also enhance the molecular stacking via forming multiple noncovalent interactions,which is favorable for reducing the energetic disorder.Therefore,in this review we focus on the design rules of NFAs,including the polymerized NFAs,of which the core moiety is substituted by various kinds of heteroatoms.We also afford a comprehensive understanding on the structure–propertyperformance relationships of these NFAs.Finally,we anticipate the challenges restricting the efficiency promotion and industrial utilization of OPV,and provide potential solutions based on the further heteroatom optimization on NFA core-moiety.