Synthesis of a New C(1→2)‐Linked Iminodisaccharide Starting from Levoglucosenone

Methyl 2‐deoxy‐2‐[(1S)‐2,5‐dideoxy‐2,5‐imino‐L ‐ribitol‐1‐C‐yl)‐α‐D ‐glucopyranoside ((+)‐ 6 ) was obtained from the product of Nozaki‐Kishi coupling of 2,5‐{[(tert‐butoxy)carbonyl]imino}‐2,5‐dideoxy‐3,4‐O‐isopropylidene‐L ‐ribose ((−)‐ 9 ) and 4‐O‐benzyl‐6‐O‐[(benzyloxy)methyl]‐3‐deoxy‐2‐O‐[(trifluoromethyl)sulfonyl]‐α‐D ‐erythro‐hex‐2‐enopyranoside ((+)‐ 12 ). The alkenyl triflate (+)‐ 12 was derived from levoglucosenone ( 1 ).     

修正多重尺度法在圆薄板大挠度弯曲问题中的应用及其渐近性研究(Ⅰ)

本文应用修正多重尺度法研究圆板在铰链和简单支承条件下的大挠度弯曲。作出其级数解,分析其边界层效应和证明其渐近性。     

Nitrogen-Based Linkers with a Mesitylene Core: Synthesis and Characterization

Mesitylene was used as a core in seven new tritopic nitrogen containing linkers. Three of the linkers, each containing three nitrile groups, were obtained through Suzuki, Sonogashira and Heck-type coupling reactions. Next, these were converted to tetrazol-5-yl moieties by the cycloaddition of sodium azide to the nitrile functionalities. The last linker, containing three 1,2,3-triazol-4-yl moieties, was synthesized by the Huisgen cycloaddition of phenyl azide to the corresponding alkyne. The latter was obtained via a Corey–Fuchs reaction sequence from the previously reported formyl derivative. As the proof of concept for their potential in MOF design, one of the nitriles was used to build an Ag-based network.     

Invariant characters and coprime actions on finite nilpotent groups

Abstract. Let S be a subgroup of SLn(R), where R is a commutative ring with identity and n \geqq 3n \geqq 3. The order of S, o(S), is the R-ideal generated by x_ij, x_ii - x_jj (i 1 j)x_{ij},\ x_{ii} - x_{jj}\ (i \neq j), where (x_ij) ? S(x_{ij}) \in S. Let En(R) be the subgroup of SLn(R) generated by the elementary matrices. The level of S, l(S), is the largest R-ideal \frak q\frak {q} with the property that S contains all the \frak q\frak {q}-elementary matrices and all conjugates of these by elements of En(R). It is clear that l(S) \leqq o(S)l(S) \leqq o(S). Vaserstein has proved that, for all R and for all n \geqq 3n \geqq 3, the subgroup S is normalized by En(R) if and only if l(S) = o(S)     

Exergetic Analysis of a Cryogenic Air Separation Unit

This case study analyzes a cryogenic air separation unit (ASU) with a production of V˙O2=58,300 [m3Nh] of gaseous oxygen with a concentration greater than 98.5%, operating in Romania on a steel plant platform. The goal of the paper is to provide an extensive model of exergetic analysis that could be used in an optimization procedure when decisional parameters are changed or structural design modifications are implemented. For each key part of the Air Separation Unit, an exergetic product and fuel were defined and, based on their definition, the coefficient of performance of each functional zone was calculated. The information about the magnitude of the exergetic losses offers solutions for their future recovery. The analysis of the exergy destructions suggests when it is worth making a larger investment. The exergetic analysis of the compression area of the ASU points out an exergy destruction and loss of 37% from the total plant’s electrical energy input. The exergy loss with the heat transferred to the cooling system of compressors can be recovered; for the exergy destruction portion, the challenge between investment and operating costs should be considered. The exergy destruction of the air separation columns found the High Pressure Column (HPC) to be more destructive than the Low Pressure Column. The share of the exergy destruction in the total plant’s electrical energy input is 8.3% for the HPC. The local COP of the HPC, calculated depending on the total exergy of the local product and fuel, is 62.66%. The calculus of the air separation column is performed with the ChemSep simulator.     

Highly Enantioselective One-Pot Synthesis of Chiral Tri- and Tetrasubstituted Ferrocenes from 1,1′-Ferrocenedicarbaldehyde

Exclusively planar chirality is exhibited by the ferrocenes obtained in a highly enantioselective synthesis in which a chiral aminoamide acts as a temporary protecting/directing group. This method was used to obtain an enantiomerically pure tetrasubstituted ferrocene, which was transformed into the first C₂-symmetric disubstituted ferrocenophane [Eq. (1)].