The effect of the third component on butadiene–propylene alternating copolymerization catalyzed by vanadium–aluminum system

The effects of five ethers and four AliBu₂OR's with varied R' on butadiene–propylene alternating copolymerization were investigated. It was found that by adding the proper third component, both the conversion and the catalytic efficiency could be increased. The effect of the third component on the valence state of vanadium ion was also studied. A model of the active center of the ternary-component catalyst system was proposed.     

超声辐射下一步法合成2-氨基-3-氰基-4-芳基-7，7-二甲基-5-氧代-5，6，7，8-四氢-4H-苯并[b]吡喃

芳醛、丙二腈和5，5-二甲基-1，3-环己二酮在乙二醇中不加任何催化剂经超 声辐射5-7min得2-氨基-3-氰基-4-芳基-7，7-二甲基-5-氧代-4H-5，6，7，8-四氢 苯并[b]吡喃，产率88％—96％．     

Microfluidic three-dimensional biomimetic tumor model for studying breast cancer cell migration and invasion in the presence of interstitial flow

Cell migration and invasion are critical steps in cancer metastasis, which are the major cause of death in cancer patients. Tumor-associated macrophages(TAMs) and interstitial flow(IF) are two important biochemical and biomechanical cues in tumor microenvironment, play essential roles in tumor progression. However, their combined effects on tumor cell migration and invasion as well as molecular mechanism remains largely unknown. In this work, we developed a microfluidic-based 3 D breast cancer model by co-culturing tumor aggregates, macrophages, monocytes and endothelial cells within 3 D extracellular matrix in the presence of IF to study tumor cell migration and invasion. On the established platform, we can precisely control the parameters related to tumor microenvironment and observe cellular responses and interactions in real-time. When co-culture of U937 with human umbilical vein endothelial cells(HUVECs) or MDA-MB-231 cells and tri-culture of U937 with HUVECs and MDA-MB-231 cells, we found that mesenchymal-like MDA-MB-231 aggregates activated the monocytes to TAM-like phenotype macrophages. MDA-MB-231 cells and IF simultaneously enhanced the macrophages activation by the stimulation of colony-stimulating factor 1(CSF-1). The activated macrophages and IF further promoted vascular sprouting via vascular endothelial growth factor(VEGFα) signal and tumor cell invasion. This is the first attempt to study the interaction between macrophages and breast cancer cells under IF condition. Taken together, our results provide a new insight to reveal the important physiological and pathological processes of macrophages-tumor communication. Moreover, our established platform with a more mimetic 3 D breast cancer model has the potential for drug screening with more accurate results.     

A New Activation Method for Electroless Metal Plating：Palladium Laden via Bonding with Self—Assembly Monolayers

A new activation method has been developed for electroless copper plating on silicon wafer based on palladium chemisorption on SAMs of APTS without SnCl2 sensitization and roughening condition.A closely packed electroless copper film with strong adhesion is successfully formed by AFM observation.XPS study indicates that palladium chemisorption occurred via palladium chloride bonding to the pendant amino group of the SAMs.     

Chemoenzymatic synthesis of highly enantiomerically enriched secondary alcohols with a thiazolic core

Stereoselective preparative enzymatic acylation and hydrolysis/methanolysis of various C-substituted rac-thiazol-2-yl-methanols were achieved for the preparation of enantiopure or enantiomerically enriched, naturally occurring 2-hydroxymethylthiazoles. The absolute configurations of the resulting secondary alcohols were determined by a detailed ¹H NMR study of Mosher’s derivatives.     

A novel turn-on fluorescent probe for Hg2+ detection based on rhodamine B spirolactam derivative

ABSTRACT

In this work, a new turn-on fluorescent probe 1 for Hg²⁺ ions detection based on rhodamine B spirolactam was reported. Among tested metal ions, probe 1 shows high selectivity towards Hg²⁺ in the the mixture solution of methanol and 0.02 M HEPES buffer (V/V = 9:1, pH = 7.2). No absorption and emission band of probe 1 was observed in the range from 450 to 700 nm. While only addition of Hg²⁺ to probe 1 could lead to appearance of a new absorption band centered at 553 nm and a fluorescence emission band around 577 nm upon excitation at 520 nm. Moreover, it exhibits excellent linear relationship (R² = 0.9993) between fluorescence intensity at 577 nm and the concentration of Hg²⁺ from 1.6 to 32 μM. The sensing mechanism was proven to be spirolactam ring open induced by Hg²⁺ through ¹H NMR, MS, absorption and fluorescence spectra. In addition, probe 1 could detect Hg²⁺ in real water samples and on filter paper, which demonstrates its application in environment science.     

Synthesis and characterization of fluorine-containing cholesteric liquid crystalline polysiloxanes bearing trifluoromethyl-substituted mesogens

A series of side-chain liquid crystal (LC) polysiloxanes were synthesised with Poly(methylhydrogeno)siloxane, 4?-(undec-10-enoyloxy) biphenyl – 4 – yl 4- (trifluoromethyl) benzoate (M_th) and a chiral nematic (N*) LC monomer 1-allyl 10-(cholesteryl)-decanedioate (M_ch). The chemical structures and LC properties of the monomers and polymers were characterised by FTIR, ¹H-NMR, differential scanning calorimetry, thermogravimetric analysis, POM and X-ray diffractometer. M_ch is monotropic N* LC. The homopolymer derived from monomer M_ch is enantiotropic N* LC. Monomer M_th is a smectic A liquid crystal. The copolymers derived from M_ch and M_th are N* LCs. The temperatures at which 5% weight loss occurred are greater than 300°C for all the fluoro-containing polymers, and the residue weights of the samples at 600°C increased slightly as the content of trifluoromethyl mesogens increased in the polymers. The glass transition temperatures of the polymers increased as trifluoromethyl mesogens increased, too. The N*–I phase transition temperatures show a negative deviate from ideal or linear behaviour. The values of the enthalpy changes for the cholesteryl containing polymers are rather low and this is attributed to the biaxiality of cholesteryl moiety which tends to reduce the change in the orientational order at the N*–I transition. Compared to the monomers, the polymers show wider mesophase region.     

片状LiV3O8软模板辅助溶胶-凝胶法制备及其在水系锂离子电池中的性能研究

负极材料是目前制约水溶液锂离子电池的关键.采用十二烷基苯磺酸钠软模板辅助的溶胶凝胶法制备了片状LiV3O8材料.XRD和SEM测试表明,目标材料为纯相的片状结构LiV3O8,属单斜晶系,P21/m点群.组装LiMn2O4//Li2SO4//LiV3O8水溶液锂离子电池,测试发现片状LiV3O8具有较高的倍率性能和较好的循环寿命.在0.1C下,LiV3O8的放电比容量为154 mAh·g-1.在1C、5C和10C时,放电容量分别为134 mAh·g-1、78 mAh·g-1和54 mAh·g-1.1C前170周循环的容量保持率约60%.     

Recognition Polymers

From the universe of polymeric materials which appear in biology and medicine we select for discussion that set whose principal function is to recognize and respond appropriately to specific substances in their environment. They may be 1.2, 2.2, or 3 dimensional shapes such as messenger RNA, cellulose acetate membranes, or artificial esophagi. They may function by recognizing the difference between right and wrong chemical species and responding by binding the correct ones and rejecting the wrong ones, e.g., enzymes and their substrates, codons and their anticodons. What happens after recognition and response is not of interest at the moment, e.g., the catalytic effect of the enzyme on the bound substrate or the codonanticodon binding effect on protein synthesis.

Another example is in the chemical senses where there is sketchy evidence that proteins are involved in recognizing tastants. This could be done by having a protein on the tongue bind all tastants (rather close contact is required to make fine distinctions) and then recognize them by very intimate contacts and sending signals to the brain for conscious recognition. Alternatively, each taste modality may have a protein that excludes all but one type and generates only one signal for the CNS.

Another important class are antibodies that recognize their own antigens out of about 10⁴ different ones and complex with them and exclude the others. A model for antigen-antibody interaction must account for the non-binding of nonantigens as well as the much simpler case of the binding of the antigen.

Another class are the permselective membranes that recognize some species and let them pass while recognizing others and not let them pass. A final class to be discussed will be implant polymers which have an un-desired ability to recognize and bind platelets.

The question we are asking is whether it is possible to establish general principles in chemical physics that govern these different types of molecular recognition so that the principles could be incorporated into polymer design. Recent advances in “intermolecular” force theory suggests that this goal is achievable in the foreseeable future. Intermolecular has been put in quotes because when two molecules are in sufficiently close contact to recognize one another they probably have an appreciable exchange term and are therefore not two molecules but one.

The recent advances referred to involve computer simulation of complex formation using the new 1-4-6-12 potential forms corresponding to a long range (R^?1) coulombic electrostatic interaction, a medium range (R^?4) electrostatic-induced dipole attraction, a short range (R^?6) dispersive attraction, and a very short range (R^?12) orbital overlap repulsion. In the cases of interest, e.g., in an aqueous environment, all four terms are important and statements such as “the binding is purely electrostatic,” i.e., all R^?1, are misleading as well as wrong (since even ions need the R^?12 repulsion to keep them at their equilibrium distance). Discussions of permeability in terms of “pore sizes” is equally limiting for it implies that only the R^?12repulsion is appreciable. The fallacy of using competitive equilibria to determine the relative contributions of terms will be discussed. The im: portant use in biology of “other contacts” within the system to give a variable base line so that the typical binding-no binding discrimination can be made with attraction-less attraction rather than the more awkward attraction-repulsion potentials will also be discussed.