固液态均荧光发射的四苯乙烯基衍生物的合成

为了打破传统荧光材料的聚集荧光淬灭（ACQ）的应用限制,通过共价键连接聚集诱导发光（AIE）分子与平面ACQ分子,可以构建在溶液中和固态下都具有荧光发射特性的化合物。分别通过多步反应合成了带有烷基硫醚的萘酰亚胺衍生物3和连接炔吡啶的四苯乙烯衍生物7。化合物3和化合物7通过酰胺缩合,合成了一种四苯乙烯-萘酰亚胺二联体化合物8,化合物8兼具荧光猝灭（ACQ）和聚集诱导发光（AIE）分子的特性。结果表明：溶液状态下化合物8具有蓝色荧光发射,其最大发射峰位于452 nm,固态下为黄绿色荧光,最大发射峰位于487 nm。利用三氟乙酸对其荧光进行调控能够实现CIE色坐标为（0.33, 0.32）的单分子白光发射。     

Vibrational and thermal properties of ScN and YN: quasi-harmonic approximation calculations and anharmonic effects

The structural, vibrational and thermal properties of rocksalt ScN and YN are investigated by using a first-principles plane-wave approach. The results are discussed in comparison with the similarly calculated results for rocksalt MgO and zincblende AlN. The thermal expansivity (α(V)) computed within the quasi-harmonic approximation shows that there are significant anharmonic effects in ScN and YN, which are comparable to those in MgO. Since no experimental results are available for α(V) of either ScN or YN, the anharmonic effects are accounted for by a variant of the very recently introduced effective semiempirical ansatz (Phys. Rev. B 2009 79 104304) for calculating anharmonic free energy, which does not require any input from experiment. The validity of this very simple approach is demonstrated first by applying it to MgO. For the considered phase of AlN, the quasi-harmonic approximation is valid up to very high temperatures, and the thus obtained α(V) is in good agreement with experiment. The values of α(V) for semiconductor transition metal nitrides that crystallize in the rocksalt phase are higher than those for the zincblende phase of group-IIIB nitrides, and a major part of these differences is due to the crystal structure.     

Vertex Cover: Further Observations and Further Improvements

Recently, there has been increasing interest and progress in lowering the worst-case time complexity for well-known NP-hard problems, particularly for the Cover problem. In this paper, new properties for the problem are indicated, and several simple and new techniques are introduced, which lead to an improved algorithm of time O(kn + 1.2852^k) for the problem. Our algorithm also induces improvement on previous algorithms for the problem on graphs of small degree.     

18 W single-stage single-frequency acoustically tailored Raman fiber amplifier

A single-mode polarization-maintaining fiber doped to increase the Raman gain while suppressing stimulated Brillouin scattering (SBS) was utilized in a single-stage counter-pumped Raman fiber amplifier. The SBS suppression was achieved through the acoustic tailoring of the core. A pump probe experiment was conducted to characterize the Brillouin gain and indicated the existence of multiple Brillouin peaks. When the amplifier was seeded with approximately 15 mW of 1178 nm light, 11.5 W of cw output power was obtained with a linewidth ≤2 MHz. The application of a thermal gradient to further mitigate the SBS process increased the output power to 18 W, thus providing a net amplifier gain >30 dB.     

Toward the improvement of the tandem halide displacement/amide coupling spiro-cyclization as a new route to γ-lactam and pyrroloisoquinoline templates

Two efficient and rapid accesses to spiro-oxindole entities bearing an imide function were presented, and their performance was compared. The key components are N-substituted α-bromoacetamides to reach these derivatives in tandem process. The resulting spiro-imides from these methodologies were regioselectively reduced into corresponding N-acyliminium precursors, which were subsequently submitted to an intramolecular cyclization to provide pentacyclic spiro-oxindole architecture analogues to pteropodine and spirotryprostatin-B alkaloids with high diastereoselective control.     

Expression of Low Endotoxin 3-O-Sulfotransferase in Bacillus subtilis and Bacillus megaterium

A key enzyme for the biosynthesis and bioengineering of heparin, 3-O-sulfotransferase-1 (3-OST-1), was expressed and purified in Gram-positive Bacillus subtilis and Bacillus megaterium. Western blotting, protein sequence analysis, and enzyme activity measurement confirmed the expression. The enzymatic activity of 3-OST-1 expressed in Bacillus species were found to be similar to those found when expressed in Escherichia coli. The endotoxin level in 3-OST-1 from B. subtilis and B. megaterium were 10⁴–10⁵-fold lower than that of the E. coli-expressed 3-OST-1, which makes the Bacillus expression system of particular interest for the generation of pharmaceutical grade raw heparin from nonanimal sources.     

Elucidation of high micro-heterogeneity of an acidic-neutral trichotoxin mixture from Trichoderma harzianum by electrospray ionization quadrupole time-of-flight mass spectrometry

The high micro-heterogeneity of an acidic-neutral trichotoxin mixture from T. harzianum, PC01, was elucidated using a modern tandem mass spectrometer equipped with an electrospray ionization source, a hybrid quadrupole-orthogonal accelerator and a reflectron time-of-flight analyzer. The trichotoxins appeared predominantly in six possible doubly charged pseudo molecular ions with three different adducts (H, Na and K) as [M + 2H](2+), [M + H + Na](2+), [M + H + K](2+), [M + 2Na](2+), [M + Na + K](2+) and [M + 2K](2+). The singly charged pseudomolecular ions, [M + H](+), [M + Na](+) and [M + K](+), occurred only in low abundance when the cone voltages were higher than 30 V. Additional singly charged fragments, b(12) and y"6 (complementary N- and C-terminal fragments), were obtained in high abundance using high cone voltages. The peak patterns of both singly and doubly charged molecular adducts revealed that this trichotoxin mixture contained several components having 6-7 molecular masses with a consecutive 14 u difference among members in the same molecular adduct series. Furthermore, well resolved isotopic peaks of every doubly or singly charged ions and their reproducible peak intensity allowed the identification of the mixing of acidic trichotoxins 1 u molecular mass heavier than the neutral counterparts in the sample. Tandem mass spectrometric (MS/MS) analyses of various singly charged b(12) and y"6 ions supported the sequence deduction of the major and minor components and also the position of Glu in the sequences of these acidic molecules. The setting of either low or high resolution of the quadrupole mass filter unit together with a suitable variation of the collision voltage for any MS/MS precursor were the tools for extracting a number of mixed components and obtaining the major and minor sequences of these precursor peaks. The nature of the MS/MS fragmentation and the data assignment of three major doubly charged ions, [M + 2H](2+), [M + K + H](2+) and [M + 2K](2+), are demonstrated. Eleven new sequences of both acidic and neutral trichotoxins are reported.     

Wavelength and beam launching effects on silica optical fiber in local area networks

In this paper, we report the modal dispersion of silica graded-index optical fibers as a function of the input mode parameters and lunching conditions in local area network (LAN) context. In that, we examine the mode-depending parameters, namely, modal delay, modal attenuation and mode-coupling effects as a function of wavelength. We show that the number of excited mode groups depends strongly on the spot beam radius when the fiber is excited with an axial Gaussian beam where we find an optimal axial diameter exciting only two mode groups. We present a comparison of the number of excited mode groups, the optimal spot radius beam, the signal penalty and the 3-dB baseband bandwidth enhancement for the optimal axial launching compared with full mode excitation, offset launching and mode-field matched axial launching.     

含有冠醚及偶氮苯基团的铂基菱形大环化合物的合成

亚硝基苯与对氨基苯甲醇反应生成偶氮苯衍生物2,衍生物2经溴代反应得到化合物3和3,5-二溴苯酚发生亲核取代反应得到化合物4,化合物4与4-乙炔基吡啶盐酸盐发生Sonogashira偶联反应得到化合物5。以3,6-二溴-9,10-菲醌为原料,先后经还原反应和亲核取代反应得到化合物7,化合物7与四(三乙基磷)铂反应生成有机金属铂配体8。化合物5和化合物8通过配位驱动自组装方法合成铂基菱形大环化合物1,其结构经核磁、质谱和紫外可见吸收光谱表征。