In vitro antioxidative activities of three marine oligosaccharides

The antioxidant activities of three marine oligosaccharides, alginate oligosaccharides (AOs), chitosan oligosaccharides (COs), and fucoidan oligosaccharides (FOs), were investigated in vitro by several antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging, erythrocyte hemolysis inhibiting, metal chelating activities, and anti-lipid peroxidation. The results show that these oligosaccharides exhibited different activities in various assays. AOs had the highest scavenging hydroxyl radical activity than FOs and COs at all the tested amounts. COs had the highest scavenging superoxide radical and inhibiting erythrocyte hemolysis activity than AOs and FOs at all the tested amounts. In the assay of chelating Fe2+, COs and FOs indicated good chelation while AOs hardly had any activity. In the assay of anti-lipid peroxidation, only COs had significantly high antioxidant activity.     

Cooperative Formation of Long‐Range Ordering in Water Ad‐layers on Fe3O4(111) Surfaces

The initial stages of water adsorption on magnetite Fe₃O₄(111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection–absorption spectroscopy (IRAS) and temperature‐programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fe_tet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self‐assembles into an ordered (2×2) structure. Water ad‐layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen‐bonding network.     

含Dawson结构杂多钨磷(砷)酸电荷转移配合物的合成、结构与性质

近年来,有机多金属氧酸盐电荷转移配合物由于有特殊的光、电、磁性质在催化、功能材料及药物化学等领域受到研究者的广泛关注［１］。自从１９８８年法国的Ｌ．Ｏｕａｈａｂ［２］首次报道（ＴＴＦ）６ＰＷ１２Ｏ４０（Ｅｔ４Ｎ）２的合成以来,已见报道的多金属氧酸盐仅限于ＡｎｄｅｒｓｏｎＥｖａｎｓｅ、ｌｉｎｄｑｕｉｓｔ和Ｋｅｇｇｉｎ结构的多阴离子,对它们功能性质的系统研究也未见文献报道。为了研究阴离子的大小和形状对标题化合物功能性质的影响,作者在以前工作的基础上［３,４］,首次以Ｄａｗｓｏｎ结构杂多钨磷（砷）…     

Large‐Scale Production of Homogeneous Helical Amylose/SWNTs Complexes with Good Biocompatibility

The key to developing novel applications of SWNTs in biotechnology and biomedicine is to improve their biocompatibility and solubility in water and to assemble them into useful architectures. We describe how amylose can help to solubilize SWNTs and wrap around SWNTs into helical superstructures with periodic pitch. FT‐IR, Raman spectroscopy, ¹H NMR and HR‐TEM are used to confirm the generation of amylose/SWNTs complexes (A/S‐C). It is demonstrated that most of the A/S‐C have similar diameters (ca. 20–30 nm) and a helical morphology with a pitch of ca. 14 nm. A test of Hela cell viability revealed that the A/S‐C had much better biocompatibility than SWNTs.

     

Cr4+∶YAG晶体的激发态吸收研究

对Cr4 + ∶YAG晶体作为 10 6 4nm激光的可饱和吸收体进行了研究。利用速率方程 ,描述了强激光下晶体的激发态吸收 (ESA)的动力学过程。用实验验证了所导出的光强与透过率的理论曲线 ,并因此论证了可以利用晶体的激发态吸收进行激光调Q ,并对其进行优化。     

金诃脑血康胶囊中微量、宏量元素的测定分析

文章采用火焰原子吸收分光光度法测定了5批藏成药金诃脑血康胶囊中镉、铬、钴、铜、铁、镁、锰、镍、铅、锌等10种微量、宏量金属元素的含量,并对其结果进行了分析。结果表明,金诃脑血康胶囊中含有丰富的宏量元素Mg和有益的微量元素Cu,Zn,Fe,Mn,Ni等,有毒元素Pb,Cd含量较低,金属元素的含量高低顺序为：Fe＞Mg＞Zn＞Mn＞Cu＞Ni＞Cr＞Pb＞Co＞Cd。测定结果为探讨藏成药中微量、宏量元素与治疗心脑血管疾病功效的关系提供了有用的数据。     

A Dendron-Based Fluorescence Turn-On Probe for Tumor Detection

Specifically amplifying the emission signals of optical probes in tumors is an effective way to improve the tumor-imaging sensitivity and contrast. In this paper, the first case of dendron-based fluorescence turn-on probes mediated by a Förster resonance energy transfer (FRET) mechanism is reported. Dendrons up to the fourth generation with a hydrophilic oligo(ethylene glycol) scaffold are synthesized by a solid-phase synthesis strategy, and show precise and defect-free chemical structures. To construct the fluorescence turn-on probe, one Cy5.5 molecule is conjugated to the focal of a G3 dendron through a robust linkage and eight Black Hole Quencher 3 (BHQ-3) molecules are conjugated to its periphery through a PEG chain bearing a reductively cleavable disulfide linkage. By in vitro and in vivo experiments, it is demonstrated that the fluorescence of the dendron-based probe can be activated effectively and rapidly in the reductive environments of tumor cells and tissues, and the probe thus exhibits amplified tumor signals and weak normal tissue signals. Compared with the reported nanoscale turn-on probes, the dendron-based probe has several significant advantages, such as well-defined chemical structure, precisely controllable fluorophore/quencher conjugation sites and ratio, desirable chemical stability, and reproducible pharmacokinetic and pharmacological profiles, and is very promising in tumor detection.     

Preparation and Cellular Uptake of pH‐Dependent Fluorescent Single‐Wall Carbon Nanotubes

Fluorescent single‐wall carbon nanotubes (SWCNTs) were prepared by mixing cut SWCNTs with acridine orange (AO). The optical absorbance and fluorescence characteristics of AO–SWCNT conjugates display interesting pH‐dependent properties. Fluorescence microscopy in combination with transmission electron microscopy proves that AO–SWCNTs can enter HeLa cells and are located inside lysosomes. The endocytosis‐inhibiting tests show that the clathrin‐mediated endocytosis is a key step in the internalization process. The internalized AO–SWCNTs remain inside lysosomes for more than a week and have little effect on cell proliferation. These findings may be useful in understanding the SWCNT‐based intracellular drug delivery mechanism and help to develop new intracellular drug transporters.     

低密度奇偶校验码的性能分析与水下通信验证

在ADSP-BF561上实现了低密度奇偶校验码的编码算法。为解决编码复杂度高的问题,将校验矩阵变换后存入数据空间。为节省存储空间,采用压缩算法,并提出相应的编码算法,没有增加复杂度。对不同码率的低密度奇偶校验码在不同信道中的性能进行仿真分析。将不同码率的低密度奇偶校验码应用于水声通信系统进行浅海试验,结果表明低密度奇偶校验码能提高通信系统的鲁棒性,码率越低性能越好。当解码前符号信噪比在7～8dB时,可达到近似无误码的通信性能。