Preparation,characterization and electrical properties of Ca and Sr doped LaCrO3

Perovskite structure chromites are one of the most important family of functional materials, especially useful as interconnect materials in solid oxide fuel cells (SOFCs). In this paper, the relationship of the structure, valence states of Cr, and electrical conductivity of La_0.8Ca_0.2CrO₃ and La_0.7Ca_0.2Sr_0.1CrO₃ were studied. The samples were synthesized by solid state reaction under air or nitrogen condition, respectively. It is found that the relationship of AC conductivity with frequency is in consistent with Jonscher power law when the frequency is between 2 × 10²–2 × 10⁶ Hz. The electrical resistivity is in line with temperature change, which means that the conduction mechanism is small polaron theory and meets Arrhenius formula. Binding energy of the Cr_2p in the compounds synthesized in air corresponded to 576.4 eV, 577.6 eV and 579.7 eV, which means the valence states of Cr are + 3, + 5 and + 6. But for the compounds synthesized in N₂ atmosphere the valence states of Cr are + 3 and + 6.     

间接喉镜下Nd:YAG激光治疗舌根乳头状瘤的临床观察

目的:观察在间接喉镜下应用Nd:YAG激光治疗舌根乳头状瘤的疗效.方法:在间接喉镜下采用自制的弯形激光切割器切除舌根乳头状瘤50例.结果:随访1年,所有病例均治愈,无复发,总有效率达100%.结论:该手术操作简单,定位准确,视野清晰,术中出血少,病人痛苦小,术后不易复发,是治疗舌根乳头状瘤一种较为安全、有效的手术方法,...     

Microwave-assisted co-precipitation synthesis of high purity β-tricalcium phosphate crystalline powders

A new fabrication technique of β-tricalcium phosphate (β-TCP) has been investigated by the microwave-assisted co-precipitation method and subsequent calcinations. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The calcium/phosphorous atomic ratio of the as-dried sample was determined by energy dispersive analysis of X-rays (EDAX). The results showed that high purity and well-crystallized β-TCP powders could be obtained in a rapid way by microwave processing. The formation process of β-TCP was explained based on the TG-DTA analysis. The effects of microwave irradiation on the reaction mechanism and reaction rate were preliminarily analyzed in the paper.     

Inhibitory Effects of Natural Compound Alantolactone on Human Non-small Cell Lung Cancer A549 Cells

Alantolactone is a natural compound identified from the roots of Inula helenium L. that has multiple bio-activities. We examined its inhibitory effects on human non-small cell lung cancer(NSCLC) A549 cells. The antiproliferative effect of alantolactone on A549 ceils was investigated via MTT[3'-(4,5dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide] assay and its apoptosis-inducing effect was determined by Hoechst staining and flow cytometry. We found that alantolactone significantly inhibited the proliferation of A549 cells and induced morphological changes typical for apoptosis. Flow cytometry analysis indicates dose-dependent cell cycle retardation at G0/G1 and S stages. The results indicate that alantolactone could be an attractive small-molecular natural compound for further development as a therapeutic drug against NSCLC.     

A Galvanic Replacement Route to Prepare Strongly Fluorescent and Highly Stable Gold Nanodots for Cellular Imaging

Fluorescent gold nanodots (GNDs) are an important kind of nanoprobes. Herein, the application of galvanic replacement for the preparation of fluorescent GNDs is reported. Using presynthesized and size‐controlled Ag nanodots (Ag NDs) as templates, the as‐prepared GNDs have strong fluorescence (quantum yields ～10%) with high stability and surface bioactivity. The resultant GNDs show excellent photoluminescence properties with high photo‐, time‐, metal‐, and pH‐stability, which are attributed to the protective surface layer of glutathione (GSH) and the presence of Au(I)–S complexes on the surface of the gold core. GSH, a naturally occurring and readily available tripeptide with carboxyl and amino functional groups, allows good dispersion of the as‐prepared GNDs in aqueous solution and favorable biocompatibility. These advantages, combined with their small size, mean that the as‐prepared GNDs have potential application in biological labeling, especially as a DNA probe for the specific detection of nucleic acids. In this study, the CAL‐27 cells are used as a model to evaluate the fluorescence imaging of GNDs.     

Surface Chemistry Routes to Modulate the Photoluminescence of Graphene Quantum Dots: From Fluorescence Mechanism to Up‐Conversion Bioimaging Applications

The bandgap in graphene‐based materials can be tuned from 0 eV to that of benzene by changing size and/or surface chemistry, making it a rising carbon‐based fluorescent material. Here, the surface chemistry of small size graphene (graphene quantum dots, GQDs) is tuned programmably through modification or reduction and green luminescent GQDs are changed to blue luminescent GQDs. Several tools are employed to characterize the composition and morphology of resultants. More importantly, using this system, the luminescence mechanism (the competition between both the defect state emission and intrinsic state emission) is explored in detail. Experiments demonstrate that the chemical structure changes during modification or reduction suppresses non‐radiative recombination of localized electron‐hole pairs and/or enhances the integrity of surface π electron network. Therefore the intrinsic state emission plays a leading role, as opposed to defect state emission in GQDs. The results of time‐resolved measurements are consistent with the suggested PL mechanism. Up‐conversion PL of GQDs is successfully applied in near‐IR excitation for bioimaging.     

紫杉醇抑制原代培养人视网膜色素上皮细胞增殖的实验研究

目的研究紫杉醇(Taxol)对体外原代培养人视网膜色素上皮(human Retinal Pigment Epithelium,hRPE)细胞增殖的抑制作用及机制。方法体外分离、原代培养hRPE细胞,采用免疫细胞化学方法对其进行鉴定。不同浓度紫杉醇(0、0.005、0.05、0.5、5mg/L)处理hRPE细胞一定时间,采用形态学观察、细胞生长曲线及MTT法检测药物对hRPE细胞的生长抑制效应,流式细胞术检测药物对hRPE细胞的细胞周期阻滞作用及凋亡诱导作用。结果原代培养的hRPE细胞胞浆富含色素,随传代次数增加,黑色素颗粒逐渐减少直至消失。用抗人细胞角蛋白抗体进行免疫细胞化学鉴定hRPE细胞呈特异的阳性反应。细胞生长曲线及MTT法显示:紫杉醇作用于hRPE细胞24h和72h,其抑制细胞生长增殖的IC50值分别为5.24和3.24mg/L。流式细胞分析术检测结果显示:0.5mg/L紫衫醇作用细胞48h即可显著延迟hRPE细胞G2/M期进展并诱导凋亡(P<0.05)。透射电镜观察显示:0.5mg/L紫杉醇作用后细胞表面微绒毛减少,电子密度增加,细胞器减少,异染色质聚集成团、边聚等。结论紫杉醇通过阻滞G2/M期进展...     

Facile Aqueous‐Phase Synthesis of Biocompatible and Fluorescent Ag2S Nanoclusters for Bioimaging: Tunable Photoluminescence from Red to Near Infrared

Low toxicity and fluorescent nanomaterials have many advantages in biological imaging. Herein, a novel and facile aqueous‐phase approach to prepare biocompatible and fluorescent Ag₂S nanoclusters (NCs) is designed and investigated. The resultant Ag₂S NCs show tunable luminescence from the visible red (624 nm) to the near infrared (NIR; 724 nm) corresponding to the increasing size of the NCs. The key for preparing tunable fluorescent Ag₂S NCs is the proper choice of capping reagent, glutathione (GSH), and the novel sulfur‐hydrazine hydrate complex as the S^2? source. As a naturally occurring and readily available tripeptide, GSH functions as an important scaffold to prevent NCs from growing large nanoparticles. Additionally, GSH is a small biomolecule with several functional groups, including carboxyl and amino groups, which suggests the resultant Ag₂S NCs are well‐dispersed in aqueous solution. These advantages make the as‐prepared Ag₂S NCs potentially applicable to biological labeling as well. For example, the resultant Ag₂S NCs are used as a probe for MC3T3‐EI cellular imaging.     

提高道路运输管理的执法水平初探

道路运输行政执法,是运输行政管理的重要内容.该文从端正执法思想、加强执法队伍建设、完善制度体系、健全监督机制等方面,对提高道路运输管理执法水平的措施进行了阐述.