Chitosan hydrogel,as a biological macromolecule-based drug delivery system for exosomes and microvesicles in regenerative medicine: a mini review

Cellulose - Extracellular vesicles are membrane-packed entities that are involved in various physiological and pathological processes. Recently, the role of exosomes and microvesicles in...     

新型暂堵酸化用自降解暂堵剂的制备及现场应用

针对传统暂堵酸化用暂堵剂颗粒耐酸性差、降解性差和除堵工艺复杂等问题，本研究通过水溶液自由基聚合法制备了一种新型的自降解暂堵剂CQZDJ。考察了单体加量、交联剂加量、引发剂加量对CQZDJ凝胶强度和降解性的影响；通过FT-IR、TGA、SEM对其结构进行表征；并对其降解机理进行了探讨；最后在长8区块的环平81-8实验井进行了现场实践。结果表明：CQZDJ凝胶强度及降解时间与单体加量、交联剂加量、引发剂加量成正比关系，且降解时间可控；降解性实验表明CQZDJ在(1%~10%)HCl溶液、水、（2%~10%）NaCl溶液中均可在4 d内完全降解，具备良好的降解性能，对地层伤害小；SEM照片显示CQZDJ的降解过程是从初始三维网状结构逐渐崩解为层状结构，最终降解为无规则线性小分子链的过程；暂堵后现场流压上升6.3 MPa，日产油由3.87 t/d增产至5.22 t/d，实现了储层的有效改造，增产效果显著。      

Phosphoric-Acid Retention in High-Temperature Proton-Exchange Membranes

Great efforts have been conducted to develop high temperature proton exchange membrane fuel cell (HT-PEMFC) due to its features of enhanced electrocatalyst reactivity, simplified hydrothermal management system and high CO tolerance of catalysts, and remarkable progress has been achieved. However, the easy leaching of phosphoric acid (PA) from the membranes during operation limits its commercial scale-up in complicated environments. This concept here mainly focuses on the recent developments for mitigation of PA loss in PEMs. The probable mechanisms of PA loss are proposed. The approaches to improve PA retention for example via introduction of phosphonic acid by covalent bond, using ion-pairs interaction and siphoning effect, and blending with inorganic nanoparticles are described in detail. Among these strategies, the siphoning effect from the intrinsic microporous PEMs is the most efficient and enables the cell to operate flexibly within a broad temperature range. Therefore, this concept may provide new ideas for the scientists to retain PA, to improve the cell performance and expand the potential applications of PA doped PEMs at elevated humidity and wide temperature range.     

Preparation of C30 concrete and its adsorption performance for Cs(I)

Journal of Radioanalytical and Nuclear Chemistry - The preparation of C30 concrete for a cavernous waste repository under construction in China and its Cs(I) adsorption performance were...     

Walsh spectrum and nega spectrum of complementary arrays

Designs, Codes and Cryptography - It has been shown that all the known binary Golay complementary sequences of length $$2^m$$ can be obtained by a single binary Golay complementary array of...     

Moderate Deviations for Extreme Eigenvalues of Real-Valued Sample Covariance Matrices

Journal of Theoretical Probability - Consider the sample covariance matrices of form $$W=n^{-1}C C^{\top }$$ , where C is a $$k\times n$$ matrix with real-valued, independent and identically...     

An elementary proof for the representation theorem of analytic isotropic tensor functions of a second-order tensor

正following Cayley-Hamilton theorem:(1)where I1, I2, and I3denote the first, second, and third principal invariants of and N-dimensional space,(2)