UV degradation of deoxyribonucleic acid

The effects of UV synchrotron radiation on deoxyribonucleic acid (DNA) cast films have been systematically investigated by vacuum ultraviolet and infrared spectrophotometry as a function of irradiation time. Cast DNA films exposed at 140 nm (8.85 eV) for different irradiation times, revealed consistent changes in their VUV spectra which indicate a decrease of thymine groups and an increase of π → π* transition spectral signature associated with the CO group of the open sugar chain. This result was corroborated by a decrease in CO stretching vibration at 1061 cm⁻¹ observed in the infrared spectra. Both these results are consistent with the creation of single strand breaks in the deoxyribose component of DNA molecule and a decrease in the phosphate groups. It was also shown that UV radiation is effective in damaging the thymine groups involved in Hoogsteen base pairing with adenine. The analysis of the infrared data suggests that the usual spectroscopic fingerprints of DNA denaturation are not necessarily a reliable measure of DNA damage.     

Oligonucleotide Analogues with Integrated Bases and Backbone. Part 22

The tritylated and silylated self‐complementary A*[s]U*[s]A*[s]U* and U*[s]A*[s]U*[s]A* tetramers 18 and 24 , linked by thiomethylene groups (abbreviated as [s]) between a nucleobase and C(5′) of the neighbouring nucleoside unit were prepared by a linear synthesis based on S‐alkylation of 5′‐thionucleosides by 6‐(chloromethyl)uridines, 7 or 10 , or 8‐(chloromethyl)adenosines, 12 or 15 . The tetramers 18 and 24 were detritylated to the monoalcohols 19 and 25 , and these were desilylated to the diols 20 and 26 , respectively. The association of the tetramers 18 – 21 and 24 – 26 in CDCl₃ or in CDCl₃/(D₆)DMSO 95 : 5 was investigated by the concentration dependence of the chemical shifts for H? N(3) or H₂N? C(6). The formation of cyclic duplexes connected by four base pairs is favoured by the presence of one and especially of two OH groups. The diol 20 with the AUAU sequence prefers reverse‐Hoogsteen, and diol 26 with the UAUA sequence Watson–Crick base pairing. The structure of the cyclic duplex of 26 in CDCl₃ at 2° was derived by a combination of AMBER* modeling and simulated annealing with NMR‐derived distance and torsion‐angle restraints resulting in a Watson–Crick base‐paired right‐handed antiparallel helix showing large roll angles, especially between the centre base pairs, leading to a bent helix axis.     

Fast solving of weighted pairing least-squares systems

This paper presents a generalization of the “weighted least-squares” (WLS), named “weighted pairing least-squares” (WPLS), which uses a rectangular weight matrix and is suitable for data alignment problems. Two fast solving methods, suitable for solving full rank systems as well as rank deficient systems, are studied. Computational experiments clearly show that the best method, in terms of speed, accuracy, and numerical stability, is based on a special {1, 2, 3}-inverse, whose computation reduces to a very simple generalization of the usual “Cholesky factorization-backward substitution” method for solving linear systems.     

One more simple proof of the Craig–Sakamoto theorem

We give one more elementary proof of the Craig-Sakamoto’s theorem: given such that ; then AB=0.     

辛代数的不变双线性型

考察了辛代数和与它相联系的李三系的双线性型之间的关系,并证明了辛代数的反对称不变双线性型可以唯一扩张到与它相联系的李三系中.作为这种关系的一个应用,得到了二次辛代数是单辛代数的一个充要条件,并证明二次辛代数的唯一分解定理.     

The boundedness of bilinear singular integral operators on Sierpinski gaskets

In the paper we give the boundedness estimate of bilinear singular integral operators on Sierpinski gasket inspired from [1].     

A reflection on the contrast between the Cooper pairing in iron-based and conventional superconductors

In this Perspective article we review retrospectively the streamline of our work on iron-based superconductors, and reflect on the mechanism of Cooper pairing in conventional and unconventional, such as iron-based superconductors. The main theme of this review is the concept of effective interaction and renormalization group.     

The Hirota bilinear method for the coupled Burgers equation and the high-order Boussinesq–Burgers equation

This paper studies the coupled Burgers equation and the high-order Boussinesq–Burgers equation. The Hirota bilinear method is applied to show that the two equations are completely integrable. Multiple-kink (soliton) solutions and multiple-singular-kink (soliton) solutions are derived for the two equations.     

On Triply Periodic Wave Solutions for(2+1)-Dimensional Boussinesq Equation

By employing Hirota bilinear method and Riemann theta functions of genus one,explicit triply periodic wave solutions for the(2+1)-dimensional Boussinesq equation are constructed under the Backlund transformation u =(1 /6)(u0 1) + 2[ln f(x,y,t)] xx,four kinds of triply periodic wave solutions are derived,and their long wave limit are discussed.The properties of one of the solutions are shown in Fig.1.     

基于相对论平均场有效对力的中子物质BCS-BEC渡越

基于核物质的相对论Hartree-Bogoliubov（RHB）理论,采用相对论平均场单玻色子交换形式的有效对相互作用,研究了不同对力强度下双中子关联及其中的BCS-BEC渡越现象。通过引入有效衰减因子χ调节对力强度,定量分析费米面处中子对能隙和单粒子动能比值△_Fn/e_Fn及无量纲参数1/（k_Fna）随费米动量k_Fn的演化行为,发现双中子对在χ=0.51时进入BCS-BEC渡越区域,在χ=0.67时可达到幺正极限。进而分析了中子对能隙、中子对波函数及相干长度等物理量在相应临界点处的特征,并给出渡越时双中子短程关联概率的定量判据。发现当配对中子处于平均中子间距以内的概率P（d_n）?0.80时,双中子对从纯BCS耦合过渡到BCS-BEC渡越区域。Based on the relativistic Hartree-Bogoliubov theory in nuclear matter, the dineutron correlations and the crossover from Bardeen-Cooper-Schrieffer (BCS) region of neutron Cooper pairs to Bose-Einstein condensation (BEC) are investigated with the one-boson-exchange type of pairing force generated from the relativistic mean field (RMF) model. By introducing an effective factor χ in the RMF effective pairing interaction, the density dependence of the ratios between neutron pairing gap at Fermi surface and neutron Fermi kinetic energy △_Fn/e_Fn and the dimensionless parameter 1/(k_Fna) are analyzed quantitatively. Then the criteria where dineutron correlations exactly reach the threshold of BCS-BEC crossover or unitary limit are determined to be χ=0.51 or 0.67, respectively. In addition, features of neutron pairing gap, Cooper pair wave function and dineutron coherence length are illustrated, and the value of the probability for partner neutrons correlated within the average inter-neutron distance, namely P (d_n) ?0.80, is obtained as a criterion of BCS-BEC crossover.