Biocompatible or biodegradable hyperbranched polymers: from self-assembly to cytomimetic applications

Self-assembly of amphiphilic hyperbranched polymers (HBPs) is a newly emerging research area and has attracted increasing attention due to the great advantages in biomedical applications. This tutorial review focuses on the self-assembly of biocompatible or biodegradable amphiphilic HBPs and their cytomimetic applications, and specialities or advantages therein owing to the hyperbranched structure have also been summarized. As shown here, various supramolecular structures including micelles, vesicles, tubes, fibers and films have been prepared through the primary self-assembly processes. The primary self-assemblies can be further assembled into more complex structures through hierachical self-assembly processes. Besides, the hyperbranched polymer vesicles have demonstrated great potential to be used as model membranes to mimic cellular behaviors, such as fusion, fission and cell aggregation. Other biomedical applications of HBPs as well as their self-assemblies are also briefly summarized.     

Explicit symplectic multidimensional exponential fitting modified Runge-Kutta-Nyström methods

This paper is concerned with multidimensional exponential fitting modified Runge-Kutta-Nyström (MEFMRKN) methods for the system of oscillatory second-order differential equations q″(t)+Mq(t)=f(q(t)), where M is a d×d symmetric and positive semi-definite matrix and f(q) is the negative gradient of a potential scalar U(q). We formulate MEFMRKN methods and show clearly the relationship between MEFMRKN methods and multidimensional extended Runge-Kutta-Nyström (ERKN) methods proposed by Wu et al. (Comput. Phys. Comm. 181:1955–1962, 2010). Taking into account the fact that the oscillatory system is a separable Hamiltonian system with Hamiltonian \(H(p,q)=\frac{1}{2}p^{T}p+ \frac{1}{2}q^{T}Mq+U(q)\), we derive the symplecticity conditions for the MEFMRKN methods. Two explicit symplectic MEFMRKN methods are proposed. Numerical experiments accompanied demonstrate that our explicit symplectic MEFMRKN methods are more efficient than some well-known numerical methods appeared in the scientific literature.     

A facile two-step etching method to fabricate porous hollow silica particles

We report here the fabrication of hollow silica particles with mesopores larger than 10 nm on their wall via a facile two-step etching method. Different from the conventional template method, the new method uses the silica particles as starting materials, which were synthesized using the well-known Stöber method. In the hollow silica preparation, first, we gently etch the silica particles with a NaOH solution without using template molecules to make them porous. Then, we coat the porous silica particles with poly-dimethyldiallylammonium chloride (PDDA) and treat the PDDA-coated porous silica with an ammonia solution to form the hollow silica nanospheres. In this study, we found that the NaOH dosage and ammonia concentration have significant impact on the morphology of the final products. Adsorption was also studied and results show that the hollow nanospheres can effectively uptake protein-based biomolecules (hemoglobin).     

易贡滑坡堰塞湖溃坝洪水分析

滑坡堰塞坝体主要由块石、碎石土等松散材料组成,随着上游水位的不断上升,极易失稳,一旦决口将对给下游人民的生命财产安全造成极大的威胁。因此,研究堰塞坝溃坝问题具有重要的学术意义和应用价值。2000 年 4 月 9 日,西藏林芝地区波密县易贡藏布河扎木弄沟发生大规模山体滑坡堵塞易贡藏布江,形成坝高60m,长约2500m,库容可达288×108m3,体积约28×108～30×108m3的滑坡堰塞湖, 2000年6月10日堰塞坝溃决。本文以易贡堰塞湖溃坝为例,从连续性方程及Navier Stokes方程出发,结合标准型湍流模型,并采用VOF方法进行自由面处理,基于流体计算软件Fluent模拟分析了溃坝洪水在下游弯曲河道的演进过程及不同位置的流速变化。数值模拟结果与实测资料记录基本一致,表明该模型能够模拟溃坝洪水在地形复杂弯曲河道中的演进过程。     

超线性收敛的指数下降迭代法

1　引　　言文[1]中借助于常微分方程的Liapunov方法建立了与非线性方程f(x)=0(1)在区间[a,b]内的解x*相对应的Cauchy问题dx/dt=-w(x)f(x)(2)x(0)=x0,　x0∈[a,b](3)其中f(x)在[a,b]上连续可导,f′(x)≠0,而w(x)满足w(x)f′(x)>0且使得Cauachy问题(2)—(3)的饱和解x=x(t,x0)存在唯一.于是非线性方程(1)在[a,b]内的解x*为自治系统(2)的渐近稳定的奇点,从而有limt→+∞x(t,x0)=x*,　　x0∈[a,b](4)成立.这说明对任一初值x0∈[a,b]通过解Cauchy问题(2)—(3)可得非线性方程(1)在[a,b]内的解x*.在文[2]中利用Lambert的非线性方法[3],导出了一个…     

Pd-catalyzed regioselective C-H chlorination of disubstituted 1,2,3-triazoles

This paper mainly studied Pd-catalyzed regioselective chlorination of disubstituted 1,2,3-triazoles directed by the 1,2,3-triazole ring. A series of regioselective chlorinated products were synthesized in 47–86% yields using Pd(OAc)₂ as a catalyst and CuCl₂ as a chlorinated reagent. This method provides a new mean for the synthesis of 1,2,3-triazole halides which combines the formation of C-X bond with C-H activation.     

Supramolecular self-assembly of inclusion complexes of a multiarm hyperbranched polyether with cyclodextrins

A new class of crystalline inclusion complexes of a multiarm hyperbranched polyether combined with various cyclodextrins (CDs) was successfully prepared. Using self-condensing ring-opening polymerization, a kind of multiarm polyether with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and multiple linear poly(ethylene glycol) (PEG) arms was obtained. It has been found that this kind of hyperbranched polyether can be dissolved in water. Adding alpha-CDs to the multiarm hyperbranched polyether solution, molecular recognition results in the formation of crystalline inclusion complexes based on the noncovalent interactions between the linear PEG arms of the polyether particles and the alpha-CDs. These multiarm polyether inclusion complexes have been well characterized. Interestingly, quite different from inclusion complexes of CDs and linear polymeric guests, the complexes of the multiarm hyperbranched polyether with alpha-CDs show a novel lamellar morphology. The experimental results validate that the resultant lamellar crystals have a juxtaposed structure. In addition, the formation mechanism of these inclusion complexes of a multiarm polyether with alpha-CDs has also been well described. Besides the role of displacement of associated water molecules and the presence of hydrogen bonding between CDs in channel structure CD inclusion complexes, the noncovalent intermolecular forces between CDs and polymers also play an important role in the formation of complex architectures.     

Selecting products through text reviews: An MCDM method incorporating personalized heuristic judgments in the prospect theory

Fuzzy Optimization and Decision Making - Online reviews have become an increasingly popular information source in consumer’s decision making process. To help consumers make informed...     

NIR analysis for batch process of ethanol precipitation coupled with a new calibration model updating strategy

Ethanol precipitation plays a major role in the pretreatment of Flos Lonicerae Japonicae of Qingkailing injection, and is also one of the most popular purification techniques in Chinese herbal medicines. In order to monitor and have a better understanding of the ethanol precipitation process, a PLS model was built based on NIR spectroscopy and HPLC analysis of chlorogenic acid content within the framework of FDA's PAT initiative. Nevertheless, due to the complex mechanism of and the raw materials’ natural variability introduced into the ethanol precipitation process, it was unable to foresee the variations in new batches which may jeopardize the robustness of the established model. Therefore, based on the simple interval calculation (SIC) theory, a new model expansion updating strategy which could continuously expand the variation coverage of the calibration model along with the batch proceeding of ethanol precipitation process was proposed. Effects of model updating were validated by an individual batch with 60 samples. After two times of updating, the root mean squared error of prediction (RMSEP) decreased from 0.268 mg mL⁻¹ to 0.199 mg mL⁻¹, while the insiders in the object status plot (OSP) increased from 44 to 58, demonstrating the good performance of the proposed approach.