EFFECT OF PHOSPHATE ION ON FLUORESCENT CHARACTERISTICS OF TYROSINE AND ITS CONJUGATE BASE

Abstract—The UV fluorescence spectrum of tyrosine (Tyr) is markedly affected by the interaction with phosphate ion. In order to elucidate the mechanism of the specific fluorescence quenching by phosphate and the simultaneous appearance of a new emission, the effect of phosphate on the spectro-scopic characteristics of Tyr was investigated. Employing a fluorimetric method, we have obtained the following results. Namely, potassium phosphate was found to enhance the fluorescence intensity of tyrosinate ion. When Tyr is excited in the phosphate-containing solution, the emission with a peak around 345 nm is observed besides the normal fluorescence of Tyr around 303 nm with a reduced quantum yield. The abnormal emission may be ascribed to the tyrosinate ion in the excited state resulting from the deprotonation of the phenolic OH group of the excited Tyr. although the tyrosinate ion in the ground state is not predominant in the aqueous solution examined.     

A novel active ester synthesis reagent (N,N′-disuccinimidyl carbonate)

A convenient reagent for active ester synthesis --N,N′-disucinimidyl carbonate-- was prepared. This reagent was useful for the preparation of active esters and peptides in stead of dicyclohexylcarbodiimide.     

FE formulation for the viscoelastic body modeled by fractional constitutive law

This paper presents finite element (FE) formulation of the viscoelastic materials described by fractional constitutive law. The time-domain three-dimensional constitutive equation is constructed. The FE equations are set up by equations are solved by numerical integration method. The numerical algorithm developed by the authors for Liouville-Riemann's fractional derivative was adopted to formulate FE procedures and extended to solve the more general case of the hereditary integration. The numerical examples were given to show the correctness and effectiveness of the integration algorithm. The project supported by the Ministry of Education of China for the returned overseas Chinese scholars     

Exemplary mathematics instruction and its development in selected education systems in East Asia

What may teachers do in developing and carrying out exemplary or high-quality mathematics classroom instruction? What can we learn from teachers’ instructional practices that are often culturally valued in different education systems? In this article, we aim to highlight relevant issues that have long been interests of mathematics educators worldwide in identifying and examining teachers’ practices in high-quality mathematics classroom instruction, and outline what articles published herein can help further our understanding of such issues with cases of exemplary mathematics instruction valued in the Chinese Mainland, Hong Kong, Japan, Singapore, South Korea, and Taiwan.     

Learning from similarities and differences: a reflection on the potentials and constraints of cross-national studies in mathematics

Research in mathematics education that crosses national boundaries provides new insights into the development and improvement of the teaching and learning of mathematics. In particular, cross-national comparisons lead researchers to more explicit understanding of their own implicit theories about how teachers teach and how children learn mathematics in their local contexts as well as what is going on in school mathematics in other countries. Further, when researchers from multiple countries and regions study collaboratively aspects of teaching and learning of mathematics, the taken-for-granted familiar practices in the classroom can be questioned. Such cross-national comparisons provide opportunities for researchers and educators to probe typical dichotomies such as “high-performing” versus “low performing”, “teacher-centred versus student-centred”, or even “East versus West”, in searching for similarities and differences in educational policies and practices in different cultural contexts.     

Second order asymptotic comparison of estimators of a common parameter in the double exponential case

Summary The problem to estimate a common parameter for the pooled sample from the double exponential distributions is discussed in the presence of nuisance parameters. The maximum likelihood estimator, a weighted median, a weighted mean and others are asymptotically compared up to the second order, i.e. the ordern ^−1/2 with the asymptotic expansions of their distributions. University of Electro-communications