微波促进的N-取代2,3,3a,4,7,7a-六氢异吲哚-1,3-二酮的Beller法合成

A rapid and facile synthesis of N-substituted 2,3,3a,4,7,7a-hexahydroisoindole-l,3-dione derivatives via microwave-promoted Beller three-component domino reaction of α,β,-unsaturated aldehydes, amides and N-substituted maleimides was described.     

Terphenyl ligand stabilized lead(II) derivatives: steric effects and lead-lead bonding in diplumbenes

The reaction of PbBr(2) with the lithium reagents LiC(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2))(2) (LiArPr(i)(2)) and Et(2)O.LiC(6)H(3)-2,6-(2,6-Pr(i)-4-Bu(t)C(6)H(2))(2) (Et(2)O.LiArPr(i)(2)Bu(t)) furnished the bromide bridged organolead(II) halides [Pb(mu-Br)ArPr(i)(2)](2) (1) and[Pb(mu-Br)ArPr(i)(2)Bu(t)](2) (2) as orange crystals. Treatment of 1 with a stoichiometric amount of methylmagnesium bromide resulted in the "diplumbene" Pr(i)(2)Ar(Me)PbPb(Me)ArPr(i)(2) (3). The addition of 1 equiv of 4-tert-butylphenylmagnesium bromide to 1 afforded the feebly associated, Pb-Pb bonded species [Pb(C(6)H(4)-4-Bu(t))ArPr(i)(2)](2) (4), whereas the corresponding reaction of tert-butylmagnesium chloride and 1 afforded the monomer Pb(Bu(t))ArPr(i)(2) (5). The reaction of the more crowded aryl lead(II) bromide [Pb(mu-Br)ArPr(i)(3)](2) (Ar = C(6)H(3)-2,6(C(6)H(2)-2,4,6-Pr(i)(3))(2)) with 4-isopropyl-benzylmagnesium bromide or LiSi(SiMe(3))(3) yielded the monomers 6, [Pb(CH(2)C(6)H(4)-4-Pr(i))ArPr(i)(3)], or 7, [Pb(Si(SiMe(3))(3))ArPr(i)(3)]. All compounds were characterized with use of X-ray crystallography, (1)H, (13)C, and (207)Pb NMR (3-7), and UV-vis spectroscopy. The dimeric Pb-Pb bonded (Pb-Pb = 3.1601(6) A) structure of 3 may be contrasted with the previously reported monomeric structure of Pb(Me)ArPr(i)(3), which differs from 3 only in that it has para Pr(i) substituents on the flanking aryl rings. The presence of these groups is sufficient to prevent the weak Pb-Pb bonding seen in 3. The dimer 4 displays a Pb-Pb distance of 3.947(1) A, which indicates a very weak lead-lead interaction, and it is possible that this close approach could be caused by packing effects. The monomeric structures of 6 and 7 are attributable to steric effects and, in particular, to the large size of ArPr(i)(3).     

On Mixed Pressure-Velocity Regularity Criteria to the Navier-stokes Equations in Lorentz Spaces,Part Ⅱ:The Non-slip Boundary Value Problem

This paper is a continuation of the authors recent work [Beir?o da Veiga, H.and Yang, J., On mixed pressure-velocity regularity criteria to the Navier-Stokes equations in Lorentz spaces, Chin. Ann. Math., 42(1), 2021, 1–16], in which mixed pressure-velocity criteria in Lorentz spaces for Leray-Hopf weak solutions of the three-dimensional NavierStokes equations, in the whole space R~3 and in the periodic torus T~3, are established. The purpose of the present work is to extend the result of mentio...     

A new proposal for the discretization of the Griffin—Wheeler—Hartree—Fock equations

A polynomial expansion is proposed as a new way to discretize the Griffin-Wheeler-Hartree-Fock equations of the Generator Coordinate Hartree-Fock method. The implementation of the polynomial expansion in the Generator Coordinate Hartree-Fock method discretizes the Griffin-Wheeler-Hartree-Fock equations through a numerical mesh which is not equally spaced. This procedure makes the optimization of Gaussian exponents in the Generator Coordinate Hartree-Fock method more flexible and more efficient. The results obtained with the polynomial expansion for atomic Hartree-Fock energies show this technique is very powerful when employed in the design of compact and high accurate Gaussian basis sets used in ab initio non-relativistic (Hartree-Fock) and relativistic (Dirac-Fock) calculations.     

Laryngeal Hyperfunction During Whispering: Reality or Myth?

For years, otolaryngologists and voice therapists have warned voice patients that whispering causes more trauma to the larynx than normal speech. However, no large series of patients has ever been examined fiberoptically during whispering to test this hypothesis. As part of our routine examination, patients are asked to count from 1 to 10 in a normal voice and in a whispered voice. We reviewed recorded fiberoptic examinations of 100 patients who had voice complaints. We compared supraglottic hyperfunction and vocal fold closure during the normal and whispered phonation of each patient. Sixty-nine percent of the patients demonstrated increased supraglottic hyperfunction with whispered voice. Eighteen percent had no change, and 13% had less severe hyperfunction. The most common glottal configuration during whisper was an inverted Y, which resulted from compression of the anterior and middle thirds of the true vocal folds. However, 12 patients had no true vocal fold contact during whispered voice, despite having adequate glottic closure with normal voice. Although whispering involves more severe hyperfunction in most patients, it does not seem to do so in all patients. In some patients, it may be less traumatic than normal voice.