Construction of Extremal Type II Codes over ℤ4

In this paper, we give a pseudo-random method to construct extremal Type II codes overℤ₄ . As an application, we give a number of new extremal Type II codes of lengths 24, 32 and 40, constructed from some extremal doubly-even self-dual binary codes. The extremal Type II codes of length 24 have the property that the supports of the codewords of Hamming weight 10 form 5−(24,10,36) designs. It is also shown that every extremal doubly-even self-dual binary code of length 32 can be considered as the residual code of an extremal Type II code over ℤ₄.     

Ring transformation of 3-halo-4-methoxycoumarins into pyrazoles with hydrazines

3-Chloro- and 3-bromo-4-methoxycoumarins 1a,b were readily transformed into 4-halo-5-(2-hydroxyphenyl)-3-oxo-2,3-dihydropyrazoles 2a,b with hydrazines. In the reaction of 1a,b with excess hydrazine and phenylhydrazine in boiling ethanol, unexpected 4-hydrazono-3-(2-hydroxyphenyl)-2-pyrazolin-5-ones 3 , 5 were obtained. The structure of 3 was determined by X-ray diffraction analysis.     

Analysis of chromatic dispersion effect on coherent optical CPFSK system and performance improvement with the use of combinations of various optical fibers

The performance of a coherent optical continuous-phase frequency shift keying (CPFSK) system is evaluated theoretically including the combined effect of fiber chromatic dispersion, non-zero laser line width and receiver noises. The system limitations imposed by chromatic dispersion and laser phase noise are depicted. The system performance can be improved by shifting the zero-dispersion wavelength to the operating wavelength of the system and this shifting can be achieved efficiently by using a suitable combination of different types of optical fibers. Dispersion shifting characteristics are demonstrated using four kinds of fibers, namely: standard single-mode fiber (SMF), dispersion shifted fiber (DSF), dispersion compensated fiber (DCF) and large core fiber (LCF). The effect of dispersion shifting on the system performance is evaluated in terms of transmission distance and bit rate.     

利用高分辨率光谱和从头算理论研究9-甲基蒽的大振幅运动

本文利用平行超音速射流和光频梳技术观察到9-甲基蒽(9MA)的多普勒的高分辨率和高精度光谱. CH₃内部旋转的势能曲线用六重对称正弦函数表示. 之前报道的9MA-d12的势垒(V₆)远远低于9MA-h12[M. Baba, et al., J. Phys. Chem. A 113, 2366 (2009)]. 本文对多组分分子轨道法进行从头算方法的理论计算. 氘代取代势垒降低的部分原因是H和D原子核的波函数不同.     

Complex Formation of Polybutadiene with Cyclodextrins

Polybutadienes were found to form inclusion complexes with cyclodextrins in high selectivity to give crystalline compounds. α‐Cyclodextrin and β‐cyclodextrin form complexes only with polybutadienes of low molecular weight and high 1,4‐addition content. Polybutadienes with high 1,2‐content gave complexes with γ‐cyclodextrin in low yield. The yields of the γ‐cyclodextrin complexes decreased with increasing molecular weights of the polybutadienes of similar composition. Complexes were isolated and characterized by means of FT‐IR, ¹H NMR, ¹³C CP/MAS NMR, ¹³C PST/MAS NMR spectroscopies, and X‐ray diffraction. Inclusion modes are discussed.     

Ring-opening fluorination of bicyclic azaarenes

We have discovered a ring-opening fluorination of bicyclic azaarenes. Upon treatment of bicyclic azaarenes such as pyrazolo[1,5-a]pyridines with electrophilic fluorinating agents, fluorination of the aromatic ring is followed by a ring-opening reaction. Although this overall transformation can be classified as an electrophilic fluorination of an aromatic ring, it is a novel type of fluorination that results in construction of tertiary carbon–fluorine bonds. The present protocol can be applied to a range of bicyclic azaarenes, tolerating azines and a variety of functional groups. Additionally, mechanistic studies and enantioselective fluorination have been examined.

A ring-opening fluorination of bicyclic azaarenes was developed. Although this overall transformation can be classified as an electrophilic fluorination of aromatics, it is a novel type of fluorination that results in construction of tert-C–F bonds.