关于TLS的可解性及扰动分析

尽管有关总体最小二乘问题的研究工作是大量的，然而ＴＬＳ可解的充分必要条件一直没有得到。本文首先给出完整的可解性分析，然后建立了ＴＬＳ的扰动上界。     

An all-electron LCGTO study of square and hexagonal plutonium monolayers

The linear combinations of Gaussian type orbitals fitting function (LCGTO-FF) method is used to study the electronic and geometrical properties of plutonium monolayers with square and hexagonal symmetry. The effects of several common approximations are examined: (1) scalar-relativity vs. full-relativity (i.e., with spin-orbit coupling included); (2) paramagnetic vs. spin-polarized; and (3) local-density approximation (LDA) vs. generalized- gradient approximation (GGA). The results indicate that spin-orbit coupling has a much stronger effect on the monolayer properties compared to the effects of spin-polarization. In general, the GGA is found to predict a larger lattice constant and a smaller cohesive energy compared to LDA predictions. We also find a significant compression of the monolayers compared to the bulk, contradicting the only other published result on a Pu monolayer. The current result supports the existence of a δ-like surface on α-Pu. Received 17 October 2001 Published online 6 June 2002     

关于二台机器自由作业的总流程问题

二台机器自由作业的总流程问题是NP困难问题．当加工时间仅依赖于机器时，该问题尚未被解决．本文对于机器均不允许空闲的约束条件下的上述问题，给出了显式解，即最优时间表的构造形式，从而改进了文献中的结果．此外，本文还对允许空闲的上述问题，作了一些讨论，指出了Vakharia和Catay一文（1997）中算法的错误．     

Novel determination of the total phenolic content in crude plant extracts by the use of H NMR of the –OH spectral region

A novel method for the determination of the total phenolic content using ¹H NMR spectroscopy in the –OH spectral region is presented. The use of DMSO-d₆, which is an aprotic and strongly hydrogen bonding solvent, allows the “appearance” of the relative sharp resonances of phenolic hydroxyl protons in the region of 8–14 ppm. The determination of the total phenolic –OH content requires three steps: (i) a 1D ¹H NMR spectrum is obtained in DMSO-d₆; (ii) a subsequent 1D ¹H NMR spectrum is recorded with irradiation of the residual water signal which results in the elimination or reduction of the phenolic –OH groups, due to proton exchange; and (iii) 1D ¹H NMR spectra are recorded with the addition of a progressively increased amount of salt, NaHCO₃, which results in extensive linebroadening of the COOH resonances thus allowing the discrimination of the phenolic from the carboxylic acid signals. Integration, with respect to the internal standard TSP-d₄, of the signal resonances between 14 and 8 ppm in spectrum (i) which are either eliminated or reduced in intensity in steps (ii) and (iii) allows the quantitation of the total phenolic content. The method was applied to model compounds, a mixture of them and several extracts of natural products. The results of the proposed ¹H NMR method were compared to the Folin-Ciocalteu (FC) reagent method. Additionally, since ¹H NMR refers to the total phenolic hydroxyl protons, a reaction factor, A_e, is proposed that corresponds to the hydroxyl reactivity. The ¹H NMR method is rapid and accurate bearing the inherent advantages of the NMR spectroscopy and can be applied directly in complex extracts. Furthermore, it can be applied in a wide range of matrixes from crude plant extracts and food products to biological samples.     

The main and modified CUPRAC methods of antioxidant measurement

The antioxidant activity/capacity levels of biological fluids and foods are measured for the diagnosis and the treatment of oxidative stress-associated diseases in clinical biochemistry, and for meaningful comparison of the antioxidant content of foods. Currently, there is no “total antioxidant” as a nutritional index available for food labeling and biological fluids due to the lack of standardized quantitative methods.The CUPRAC (CUPric Reducing Antioxidant Capacity) method of antioxidant measurement, introduced by our research group, is based on the absorbance measurement of Cu(I)-neocuproine (Nc) chelate formed as a result of the redox reaction of chain-breaking antioxidants with the CUPRAC reagent, Cu(II)-Nc, where absorbance is recorded at the maximal light-absorption wavelength of 450 nm.We introduce the main CUPRAC method and describe modifications to it in the past six years.     

Facile synthesis of salmochelin S1, S2, MGE, DGE, and TGE

Salmochelin S1, S2, MGE, DGE, and TGE were prepared through amide bond connection of an aryl C-glucosyl acyl chloride (Ar¹COCl) and serine ester amines, followed by hydrogenolysis of the per-benzylated precursors. Each synthesis employed a highly diastereoselective Ni-catalyzed Negishi approach to the aryl C-glycoside subunit.     

Facile Access to Sterically Hindered Aryl Ketones via Carbonylative Cross-Coupling: Application to the Total Synthesis of Luteolin

A general and mild protocol for achieving the carbonylative cross-coupling of sterically hindered, ortho-disubstituted aryl ketones is reported. The commercially available PEPPSI-IPr catalyst is shown to efficiently promote the carbonylative cross-coupling of hindered ortho-disubstituted aryl iodides to give diaryl ketones; traditional phosphine catalysts are less effective. Carbonylative Suzuki-Miyaura cross-couplings provide a diverse array of biaryl ketones in good to excellent yields. The same catalyst is also shown to catalyze a carbonylative Negishi cross-coupling reaction, utilizing a variety of alkynyl-zinc reagents to give the corresponding alkynyl aryl ketones. Application of this new methodology to the synthesis of the natural product luteolin is reported.     

Enantioselective syntheses of the assigned structures of the helibisabonols A and B

The enantioselective syntheses of the compounds with the assigned structures of the helibisabonols A and B have been accomplished. Using an enzymatic desymmetrization of the σ-symmetrical diol (route a) and a diastereoselective conjugate addition of the methyl to the enone with a chiral auxiliary (route b) we constructed the key tertiary stereogenic center at the benzylic position (C7) and then used an asymmetric dihydroxylation for assembling the C10 stereogenic center. In addition, possible diastereoisomers of the natural products were prepared and detailed comparisons of the ¹H and ¹³C NMR spectra were conducted. As a result, the structure originally assigned to helibisabonol A may be revised to (7R,10R)-1. In the case of helibisabonol B, the (7R,10R)-2 would be reasonable based on a comparison of the NMR data and the biogenetic parallelism with helibisabonol A.     

First total synthesis of tripdiolide

The first total synthesis of tripdiolide 1 from the readily available abietic acid 3 in 22 steps is described and this synthesis furnishes a 5.8% overall yield of 1 with an average yield of 87%.     

Total synthesis of pyripyropene A

The total synthesis of pyripyropene A, a potent ACAT2 inhibitor with high isozyme selectivity, was completed. Key features of the synthetic strategy include Ti(III)-mediated radical cyclization and Peterson olefination for the construction of the AB ring segment and stereoselective dihydro-γ-pyrone formation (C-ring). The total synthesis provided pyripyropene A in 5.3% overall yield over 17 steps.