The use of oil-soluble radical generators for emulsion polymerization is considered. When radicals are formed in pairs within particles of a seed latex, the occurrence of radical desorption leads to complex kinetics. Use of radical balances and realistic simplifications produce a method for a relatively simple calculation of radical populations in the particles. Examples are restricted, for illustration purposes, to cases where the average number of radicals per particle, n , is less than one. Very low rates of radical desorption cause a substantial increase in n . As the desorption rate increases, the value of n decreases. n increases slowly with radical generation rate. Large decreases in the chain termination rate coefficient (which may accompany a gel effect) can have a negligible effect on the value of n . Radical distributions obtained from oil-soluble initiators can be slightly broader than those expected from the use of water-soluble initiators. The kinetics of emulsion polymerization will be similar for the two types of radical generator when radicals from oil-soluble generators can desorb from the polymer particles. 相似文献
Intramolecular [2 + 2] cycloaddition of two C=C bonds in vinylidene complexes [Ru(eta5-C9H7){=C=C(R)H}(PPh3){kappa1-(P)-PPh2(C3H5)][BF4] affords cyclobutylidene complexes [Ru(eta5-C9H7){kappa2-(P,C)-(=CC(R)HCH2CHCH2PPh2)}(PPh3)][BF4], which can be also obtained by reaction of terminal alkynes with [Ru(eta5-C9H7)(PPh3){kappa3-(P,C,C)-PPh2(C3H5)}][PF6]. The reaction proceeds under mild conditions via vinylidene complexes, and the activation parameters were determined by kinetic studies. 相似文献
This paper describes a calorimetric study of the association of a series of seven fluorinated benzenesulfonamide ligands (C6HnF5?nSO2NH2) with bovine carbonic anhydrase II (BCA). Quantitative structure–activity relationships between the free energy, enthalpy, and entropy of binding and pKa and log P of the ligands allowed the evaluation of the thermodynamic parameters in terms of the two independent effects of fluorination on the ligand: its electrostatic potential and its hydrophobicity. The parameters were partitioned to the three different structural interactions between the ligand and BCA: the ZnII cofactor–sulfonamide bond (≈65 % of the free energy of binding), the hydrogen bonds between the ligand and BCA (≈10 %), and the contacts between the phenyl ring of the ligand and BCA (≈25 %). Calorimetry revealed that all of the ligands studied bind in a 1:1 stoichiometry with BCA; this result was confirmed by 19F NMR spectroscopy and X‐ray crystallography (for complexes with human carbonic anhydrase II). 相似文献
The microwave spectrum of gaseous bromomethyl cyclopropane is reported in the range 12 to 36 GHz. Lines of the 79Br and 81Br species of cis and gauche forms are assigned and partial r0-structures derived. The rotational constants in MHz are: gauche C3H5CH279Br, A = 11 469.285, B = 1 374.777, C = 1 295.394; gauche C3H5CH281Br, A = 11 400.100, B = 1 364.088, C = 1 283.952; cis C3H5CH279Br, A = 8 759.918, B = 1 597.413, C = 1 522.141; cis C3H5CH281Br, A = 8 716.552, B = 1 583.761, C = 1 509.017. 相似文献
Pyroptosis is a programmed cell death widely studied in cancer cells for tumour inhibition, but rarely in dendritic cell (DC) activation for vaccine development. Here, we report the synthesis of sodium stabilized mesoporous aluminosilicate nanoparticles as DC pyroptosis modulators and antigen carriers. By surface modification of sodium-stabilized four-coordinate aluminium species on dendritic mesoporous silica nanoparticles, the resultant Na-IVAl-DMSN significantly activated DC through caspase-1 dependent pyroptosis via pH responsive intracellular ion exchange. The released proinflammatory cellular contents further mediated DC hyperactivation with prolonged cytokine release. In vivo studies showed that Na-IVAl-DMSN induced enhanced cellular immunity mediated by natural killer (NK) cells, cytotoxic T cells, and memory T cells as well as humoral immune response. Our results provide a new principle for the design of next-generation nanoadjuvants for vaccine applications.Na-IVAl-DMSN acts as both antigen carriers and modulators to “hyperactivate” dendritic cells (DCs) via potassium (K+) efflux dependent pyroptosis, eventually leading to enhanced adaptive and innate immunity.相似文献
A one-step synthesis of fluorotamoxifen from tamnoxifen is described. Attempts to achieve synthesis of the title compound by fluorodestannylation or transmetallation were unsuccessful. 相似文献