Intrinsic Efficiency of A Φ76mm×100mm BGO Scintillation Detector

With several monoenergetic gamma-rays generated at low energy(p,γ)resonant nuclear reactions,the full-energy-peak intrinsic gamma-rays detecting efficiencies of a Φ 76 mm×100mm BGO scintilation detector were measured as below:7%、9%、22% at 17.65、17.23 and 6.13MeV gamma-rays energy,respectiviy.     

Iron-Catalyzed Highly Enantioselective cis-Dihydroxylation of Trisubstituted Alkenes with Aqueous H2O2

Reliable methods for enantioselective cis-dihydroxylation of trisubstituted alkenes are scarce. The iron(II) complex cis-α-[Fe^II(2-Me₂-BQPN)(OTf)₂], which bears a tetradentate N₄ ligand (Me₂-BQPN=(R,R)-N,N′-dimethyl-N,N′-bis(2-methylquinolin-8-yl)-1,2-diphenylethane-1,2-diamine), was prepared and characterized. With this complex as the catalyst, a broad range of trisubstituted electron-deficient alkenes were efficiently oxidized to chiral cis-diols in yields of up to 98 % and up to 99.9 % ee when using hydrogen peroxide (H₂O₂) as oxidant under mild conditions. Experimental studies (including ¹⁸O-labeling, ESI-MS, NMR, EPR, and UV/Vis analyses) and DFT calculations were performed to gain mechanistic insight, which suggested possible involvement of a chiral cis-Fe^V(O)₂ reaction intermediate as an active oxidant. This cis-[Fe^II(chiral N₄ ligand)]²⁺/H₂O₂ method could be a viable green alternative/complement to the existing OsO₄-based methods for asymmetric alkene dihydroxylation reactions.     

抛物型方程广义解的Phragmen-Lindelf原理

设Ω为Ｅｎ中的无界，连通区域．在Ω×（０，∞）上考虑抛物型方程：设，Ｂ满足结构条件：设存在和，使对任何ρ０＞ρ１＞０：设ｕ是方程的广义解，并且如果ｕ在Ω×（０，Ｔ）为有界，那么ｕ＋≤０．     

一致抛物型方程广义解的弱最大值原理和唯一性定理

Trudinger和Gilbarg—Trudinger对椭园型方程的广义解推广了古典的最大值原理,唯一性定理也有新发展。现在我们把结果推广到一致抛物型方程的第一边值问题。 设Ω是n维欧氏空间E~n中的有界域,Ω为其边界,Q=Ω×(O,T),T是有限值。用(Q)记空间W_2~1(Q)的子空间,其函数在意义下满足如下边界条件: u(x,0)=0,x∈Ω和u(x,t)=0,x∈Ω,t∈(0,T)。 在Q考虑下面形状的方程     

对角型蜕化椭圆组广义解的有界性和可积性

考虑一类对角型蜕化椭圆组,证明广义解的有界性和L_Ф-可积性.