The rapid synthesis of the heteropolyoxometalate-pillared layered double hydroxide Zn2Al(OH)6[SiW11O39Co(H2O)]1/6 · 4H2O by the action of ultrasound

The ion-exchange between the transition metal monosubstituted heteropolyoxometalate anion [SiW11O39-Co(H2O)]6– and the anionic clay Zn2Al(OH)6NO3· xH2O by the action of ultrasound gave the heteropolyanion-pillared layered double hydroxide Zn2Al-(OH)6[SiW11O39Co(H2O)]1/6·4H2O within 7 min. The product was characterized by powder X-ray diffraction, i.r. spectroscopy and elemental analysis. The results show that the gallery height of the complex is 1.00±0.02 nm and the heteropolyanion [SiW11O39-Co(H2O)]6– entering the layer retains the integrity of the Keggin structure. Experimentally, the atomic ratio of each element in the formula is Zn:Al = 2.1:0.95 and Si:W:Co = 0.96:10.90:0.98.     

Discrete nonlinear Schrödinger equation and polygonal solitons with applications to collapsed proteins

We introduce a novel generalization of the discrete nonlinear Schr?dinger equation. It supports solitons that we utilize to model chiral polymers in the collapsed phase and, in particular, proteins in their native state. As an example we consider the villin headpiece HP35, an archetypal protein for testing both experimental and theoretical approaches to protein folding. We use its backbone as a template to explicitly construct a two-soliton configuration. Each of the two solitons describe well over 7.000 supersecondary structures of folded proteins in the Protein Data Bank with sub-angstrom accuracy suggesting that these solitons are common in nature.     

A study on effect of sonochemistry in a reverberation field

In this paper,an ultrasound with frequency of 815 kHz was used to re-search the sonochemical yield in a small-size reverberation field by the methodof fluorescent spectrum analysis.There are two characteristics on the effect ofsonochemistry in the reverberation field:First,the cavitation threshold wasabout 0.3W/cm~2(it was 0.7W/cm~2 in travelling field);Second,when thesound intensity was larger than the threshold,the sonochemical yield increasedas the intensity increased and increased rapidly after the intensity was at1.69-2.13W/cm~2,so that there was a upturned point in the curve of the result(which would tend to saturation in the travelling field).The theoretical analysisshows that the reason of the threshold decrease is that the sound energy densitybecomes high in the reverberation field,and the upturned point results from thedisturbance of the radiation pressure on the liquid surface.Therefore,by exper-iment and theory this paper shows that a reverberation field has to be built forthe higher sonoche     

Aromatic Nucleophilic Substitution by Arylselenolate Ions Produced Through Reductive Cleavage of Diaryl Diselenide Induced by SmI2-THF-HMPA System

Arylselenolate Ions which were produced through reductive cleavage of Se-Se bond in diaryl diselenide undergo nucleophilic substitution on aromatic rings and a series of new unsymmetrical diaryl selenides were synthesized.     

Palladium-catalysed α-allylation of chiral sulfinimines derived from symmetric cyclic ketones

A diastereoselective mono-allylation reaction at the α-position of symmetric cyclic ketones by using tert-butanesulfinamide as a chiral auxiliary is explored. Excellent yields and high diastereomeric ratios were achieved under palladium(0) catalysis in the presence of a readily available achiral phosphine ligand.     

元认知理论对物理实验教学研究的启示

论述了元认知在物理实验教学的中作用,同时指出了元认知理论给物理实验教学带来的启示,这一启示将给物理实验教学研究提供一种新的方法。     

用碘释放法研究双束超声辐照的脉冲空化峰

本文使用双束同频脉冲超声水平正交辐照,通过磺释放法检测,发现双束同频水平正交辐照亦可观察到明显的空化峰现象及声化学产额增长。