The pointwise estimates on walsh overconvergence

Let f∈A_p. For any positive integer l, the quantity Δ_1,n−1(f:z) has been studied extensively. Here we give some quantitative estimates for and investigate some pointwise estimates of Δ _l,n−1 ^(r) (f;z). Supported by National Science Foundation of China     

K2NiF4型结构的A2－xSrxBO4(A＝La, Dy, B＝Mn, Fe, Co, Ni)希土复合氧化物的合成

以典型的轻希土镧和重希土镝及碱土金属锶作为Ａ位离子，以过渡金属锰、铁、钴、镍作为Ｂ位离子，合成了Ｋ２ＮｉＦ４型结构的Ａ２－ｘＳｒｘＢＯ４希土复合氧化物，采用粉末Ｘ射线衍射技术考察了反应条件等因素对生成Ｋ２ＮｉＦ４型四方（Ｔ）结构上析影响，实现结果表明，四方结构的形成不仅与几何因素有关，而且与各组分的物理化学性质有关。各个不同的组成，生成四方相的温度范围也有所不同。适当地提高反应温度以及延长灼烧时间     

非线性光学材料──水草酸铵

一水草酸铵（简称ＡＯＭ）是一种优良的电光晶体￣［１］。文献￣［１，２］报道了该晶体的晶体结构，化学式为（ＮＨ＿４）＿２Ｃ＿２Ｏ＿２·Ｈ＿２Ｏ，属正交晶系，Ｐ２２２空间群，晶胞参数ａ＝０．８０３５ｎｍ，ｂ＝１。０３１ｎｍ，ｃ＝０．３８０１ｎｍ，ｚ＝２。本文拟报道ＡＯＭ单晶生长，热化学分析，透过波段以及非线性光学性质的初步研究。     

CAROTENOID TRIPLET STATES IN PHOTOSYNTHETIC BACTERIA

Abstract— The triplet state spectra of anaerobically grown cells of Rhodopseudomonas sphaeroides GIC and R. sphaeroides wild type and aerobically grown cells of R. sphaeroides wild type were examined under reducing and non-reducing conditions at 100 K. by electron paramagnetic resonance (EPR). Large differences in the zero field splitting parameters, |D| and |E| of the triplets are seen to arise in the different preparations. The spectra are assigned to the triplet states of carotenoids, some of which are closely associated with the reaction center and others are contained in the light harvesting complex. Taken together with the triplet state data on Rhodospirillum rubrum wild type previously published the trends in the zero field splitting parameters can be understood in terms of the extent of electron derealization in carotenoids of varying length.     

Phenolic compounds from Anaphalis aureo-punctata

From the ethanolic extract of the whole plant of Anaphalis aureo-punctata, a new acylated flavonoid glycoside 3-O-kaempferol-3-O-acetyl-6-O-(p-coumaroyl)-β-D-glucopyranoside (1), and five known phenolic compounds 3-O-kaempferol-6- O- ( p-coumaroyl )-β-D-glucopyranoside ( 2 ), kaempferol-3- O-β-D-glucopyranoside 3,6-(4′-hydroxystyryl)-4-methoxy-2-pyrone (4), 2H-pyran-2-one, 6-[ 2-( 4-(β-D-glucopyranosyloxy ) phenyl ) ethenyl ]-4-methoxy-( E ) (5) and 4-hydroxy-3-methoxycinnamic hexacosyl ester (6) were isolated. Their structures were established by spectral methods (UV, IR, MS, 1D, 2D-NMR). The flavonoid glycosides, 1, 2 and 3 showed markedly inhibited oxidative DNA strand breaks induced by Fenton reaction and NADH/PMS in a concentration-dependent manner.     

The preparation of 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides by the condensation/cyclization of trilithiated acetoacetanilides with lithiated methyl salicylates

Several acetoacetanilides were trilithiated in excess lithium diisopropylamide, and the resulting polylithiated intermediates were regioselectively condensed with lithiated methyl salicylates followed by acid cyclization to substituted 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides (benzopyranone-2-acetamides).     

Ba(1S)+N2O反应的化学发光偏振研究

The variation of ehemiluminescent polarization for reaction Ba(~1S)+N_2O with respect to the Ba beam temperature or the average collision energy E_(rtr) was studied under the single collision condition on beam-gas apparatus. If E_(rtr)<0.06 eV, the distribution of rotational angular momentum for product BaO, i.e. -, increased with the impact energy; while E_(rtr)>0.06 eV, - decreased with the E_(rtr). It is plausible to point out the corresponding relationship between the characteristics of the reaction potential surface and the conformation of the intermediate complexes.     

Intramolecular dimers: a new design strategy for fluorescence-quenched probes

Fluorogenic probes dual-labeled with reporter and quencher dyes use a change in fluorescence to monitor biochemical events (e.g., substrate binding or enzyme digestion). Such events change the reporter-quencher distance, which affects fluorescence. Recently, it is has been shown that static quenching through intramolecular dimers is an important mechanism that can sometimes be more efficient than F?rster resonance energy transfer (FRET).     

Speciation and biosynthetic variation in four dictyoceratid sponges and their cyanobacterial symbiont, Oscillatoria spongeliae

Four species of marine sponges (Phylum Porifera, Order Dictyoceratida), which contain the filamentous cyanobacterial symbiont Oscillatoria spongeliae, were collected from four locations in Palau. The halogenated natural products associated with the symbiont were characterized from each sample, revealing that each species contained either chlorinated peptides, brominated diphenyl ethers, or no halogenated compounds. Analysis of the host sponges and the symbionts indicated that each species of sponge contained a distinct strain of morphologically similar cyanobacteria. Although cospeciation may be present in this group, we have identified that at least one host switching event has occurred in this symbiosis. Only the strain of O. spongeliae in the sponge containing the chlorinated compounds possessed genes involved in the biosynthesis of chlorinated leucine precursors, indicating that the chemical variation observed in these animals has a genetic foundation.