Shortest Path Problem on a Network with Imprecise Edge Weight

A network with its arc lengths as imprecise number, instead of a real number, namely, interval number and triangular fuzzy number is considered here. Existing ideas on addition and comparison between two imprecise numbers of same type are introduced. To obtain a fuzzy shortest path from a source vertex to all other vertices, a common algorithm is developed which works well on both types of imprecise numbers under consideration. In the proposed algorithm, a decision-maker is to negotiate with the obtained fuzzy shortest paths according to his/her view only when the means are same but the widths are different of the obtained paths. Otherwise, a fuzzy optimal path is obtained to which the decision-maker always satisfies with different grades of satisfaction. All pairs fuzzy shortest paths can be found by repeated use of the proposed algorithm.     

The Role of the Pars Recta and Pars Oblique of Cricothyroid Muscle in Speech Production

To evaluate the functional difference of the pars recta and pars oblique during speech production, the electromyographic activities of these muscles were measured in thyroidectomized patients. The hooked wire electrodes were inserted into the normal side of the bellies of the pars recta and pars oblique bundles. Two kinds of sentences were used to obtain pitch changes, a simple interrogative sentence and a complex sentence with stress contrasts. The pars recta and pars oblique were simultaneously activated for initial lengthening and tensing of vocal folds to produce speech. The pars oblique might be initially more active than the pars recta at the initial task of speech and the pars recta might be more active at the pitch elevation in the interrogative sentence and the stress contrast of the complex sentence. The maximum electromyographic activity range of the pars recta and pars oblique seemed to be nearly equal. These results demonstrated that the patterns of electrical activities of the two bellies are different during speech and the combined activities of the pars recta and pars oblique are important in the adjustment of the vocal fold length during speech.     

Synthesis and structural studies of early transition metalloporphyrin complexes. 1. X-ray structures of meso-5,10,15,20 tetratolyl hafnium(IV) μ-dioxo dimer complex and meso-5,10,15,20 tetratolyl porphyrin vanadium(IV) oxo complex

Abstract

(TTP) hafnium dichloride, 1, where TTP = meso-5,10,15,20 tetratolyl porphyrin dianion, has been synthesized and spectroscopically characterized as a precursor to 2. Hydrolysis of 1 gives (TTP) hafnium μ-dioxo dimer, 2. (TTP) vanadium oxo complex, 3, can be obtained by hydrolysis of the corresponding chloro complex. Compound 2 has been characterized by spectroscopic and single crystal X-ray diffraction analyses. [(TTP)HfO]₂-toluene crystalizes in the space group C2/c, a = 31.906(6) Å, b = 16.864(3) Å, c = 19.180(4) Å, β = 117.52(3)°, V = 9152(3) ų, d_calcd = 1.369 g/cm³, Z = 8, 6029 unique observed reflections, final R = 0.077. The Hf atom is 1.02 Å from the plane of the porphyrin ring; Hf-O bond lengths are 2.1 Å. The hafnium atoms are 3.06(1) Å from each other and the average Hf-O-Hf angle is 94°. The porphyrin rings are 5.4° from being parallel and the distance between the centers of the porphyrin rings is ～ 5.1 Å. TTPVO·mesitylene, 3, crystallizes from mesitylene in the space group P1, a = 8.365(2), b = 10.320(3), c = 14.380(5) Å, α = 91.91(3), β = 91.44(3), γ = 108.26(2)°, V = 1177.2(6) ų, d_calcd = 1.27 g/cm³, Z = 1, 1851 observed unique reflections, final R = 0.069. The average V - N distance = 2.016 Å. The coordination geometry around the vanadium is distorted C_4V. The V = O group is disordered about the center of inversion. The vanadium atom resides 0.57 Å above the plane of the nitrogens. The (ring center) -V = O angle is 165.9° while the V = O vector is essentially colinear with the vector normal to the plane of nitrogens.     

Functional model of oxomolybdoenzymes: Synthesis and characterization of a molybdenum complex with sulphur and pterin ligands exhibiting saturation kinetics with pyridine N-oxide

Redox reaction between 6-acetonylisoxanthopterin (H₂pte) and [Mo^VIO₂ (ssp)] [ssp = anion of 2-(salicylideneamino) benzenethiol] in CH₃OH-C₂H₅OH medium produces a new mixed ligand compound [Mo^IV (ssp) (Hpte) (OCH₃)] (1). It has been characterized by elemental analysis, ESMS data, UV-Vis, IR,¹HNMR (1D and 2D) spectroscopy and cyclic voltammetry. Kinetics of formation of this compound as well as that of its reaction with pyridine N-oxide have been followed spectrophotometrically. Both the reactions follow substrate saturation kinetics and involve metal-centred oxygen atom transfer process. Large negative values of entropy of activation indicate the operation of associative mechanism.     

镜像配基筛选:克服“酶屏障”的多肽、寡核苷酸药物研发技术

生物体内存在的酶屏障是功能性多肽和寡核苷酸成药的重要瓶颈.以镜像噬菌体展示技术(mirror-image phage display)和镜像适配体筛选技术(Spiegelmer technology)为代表的镜像配基筛选技术能有效地克服这一屏障,获得对靶点具有特异识别能力且在生理条件下高度稳定的D型多肽和L型寡核苷酸配基,有望成为多肽或寡核苷酸类特异性药物研发的有利工具.本文主要综述镜像配基筛选技术的原理及其在药学领域的研究进展.