Preparation of Porous Ellipsoidal Bismuth Oxyhalide Microspheres and Their Photocatalytic Performances

Well-dispersed and uniform porous ellipsoidal-shaped bismuth oxyhalides (nominal composition: 80%BiOCl/20%BiOI) microspheres were obtained by a facile solvothermal method, in which process the use of polyvinylpyrrolidone (PVP) as template agent was found to be crucial. At 150 °C, elliptical porous particles with a particle size of 0.79 μm were formed. Instead of forming solid solutions, the study of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that the prepared 80%BiOCl/20%BiOI microspheres are composite of BiOCl and BiOI in nature and the obtained crystallite size is about 5.6 nm. The optical bandgap of 80%BiOCl/20%BiOI was measured to be 2.93 eV, which is between the bandgap values of BiOCl and BiOI. The 80%BiOCl/20%BiOI microspheres were able to decompose various organic dyes (rhodamine B-RhB, methyl orange-MO, methylene blue-MB, methyl violet-MV) under an illuminated condition with the degradation rate in the order of RhB > MB > MV > MO, and 98% of RhB can be degraded in 90 min. Radical scavenger tests showed that photogenerated holes are the main active species for the photocatalytic decomposition of all of the tested organic dyes. Our results show that the obtained porous ellipsoidal-shaped 80%BiOCl/20%BiOI microspheres are promising for the degradation of various organic pollutants under the illumination of visible light.     

Effect of Fe-Doping on Thermal Expansion and Stability of Bismuth Magnesium Tantalate Pyrochlorere

A continuous series of solid solutions (Bi_1.5Mg_0.75−xFe_xTa_1.5O_7±Δ (x = 0–0.75)) with the pyrochlore structure were synthesized with the solid-phase method. It was shown that iron, like magnesium, is concentrated in the structure in the octahedral position of tantalum. Doping with iron atoms led to an increase in the upper limit of the thermal stability interval of magnesium-containing pyrochlore from 1050 °C (x = 0) up to a temperature of 1140 °C (x = 1). The unit cell constant a and thermal expansion coefficient (TEC) increase uniformly slightly from 10.5018 Å up to 10.5761 Å and from 3.6 up to 9.3 × 10⁻⁶ °C⁻¹ in the temperature range 30–1100 °C. The effect of iron(III) ions on the thermal stability and thermal expansion of solid solutions was revealed. It has been established that the thermal stability of iron-containing solid solutions correlates with the unit cell parameter, and the lower the parameter, the more stable the compound. The TEC value, on the contrary, is inversely proportional to the cell constant.     

The Crystalline Structure of Thin Bismuth Layers Grown on Silicon (111) Substrates

Bismuth films with thicknesses between 6 and ∼30 nm were grown on Si (111) substrate by molecular beam epitaxy (MBE). Two main phases of bismuth — α-Bi and β-Bi — were identified from high-resolution X-ray diffraction (XRD) measurements. The crystal structure dependencies on the layer thicknesses of these films were analyzed. β-Bi layers were epitaxial and homogenous in lateral regions that are greater than 200 nm despite the layer thickness. Further, an increase in in-plane 2θ values showed the biaxial compressive strain. For comparison, α-Bi layers are misoriented in six in-plane directions and have β-Bi inserts in thicker layers. That leads to smaller (about 60 nm) lateral crystallites which are compressively strained in all three directions. Raman measurement confirmed the XRD results. The blue-sift of Raman signals compared with bulk Bi crystals occurs due to the phonon confinement effect, which is larger in the thinnest α-Bi layers due to higher compression.     

毛细管气相色谱法测定胶体果胶铋中甲醇和乙醇的残留量

目的 测定胶体果胶铋中甲醇和乙醇的残留量.方法 采用直接进样的毛细管气相色谱法,色谱柱是以硝基对苯二甲酸改性的聚乙二醇为固定相的石英毛细管柱(30 m×0.53 mm×0.5μm),采用程序升温、氢焰离子化检测器,以内标法计算残留溶剂的含量.结果 两种溶剂的分离良好,甲醇和乙醇的线性范围分别为0.3～300.4 μg·mL~(-1)(r=0.9995,n=7)和0.5～501.2μg·mL~(-1)(r=0.9994,n=7);平均回收率分别为100.6%、99.3%,RSD分别为2.2%、3.1%(n=9);定最限分别为1.19、0.71 ng;检测限分别为0.24、0.14 ng.结论 所用方法简单、灵敏、准确,适用于胶体果胶铋中有机溶剂残留量的测定.     

奥美拉唑、枸橼酸铋钾、呋喃唑酮、阿莫西林联合治疗Hp阳性的消化性溃疡的临床研究

目的 观察奥美拉唑、枸橼酸铋钾、阿莫西林、呋喃唑酮短程四联治疗消化性溃疡的疗效及幽门螺杆菌根除率.方法 53例Hp阳性的消化性溃疡患者,予以奥美拉唑、阿莫西林、呋喃唑酮,连续1周.四联治疗结束4周后,复查胃镜及钳取胃窦黏膜行快速尿素酶试验检测幽门螺杆菌.结果 溃疡治愈率为100%、幽门螺杆菌根除率为96.2%.结论 四联用药治疗消化性溃疡,对Hp的根除作用及对溃疡愈合率均较理想,达到了临床较理想的效果.     

Raman Spectroscopy of Two-Dimensional Bi2TexSe3 ? x Platelets Produced by Solvothermal Method

In this paper, we report a facile solvothermal method to produce both binary and ternary compounds of bismuth chalcogenides in the form of Bi₂Te_xSe_{3 − x}. The crystal morphology in terms of geometry and thickness as well as the stoichiometric ratio can be well controlled, which offers the opportunities to systematically investigate the relationship between microstructure and phonon scattering by Raman spectroscopy. Raman spectra of four compounds, i.e., Bi₂Se₃, Bi₂Se₂Te, Bi₂SeTe₂ and Bi₂Te₃, were collected at four different excitation photon energies (2.54, 2.41, 1.96, and 1.58 eV). It is found that the vibrational modes are shifted to higher frequency with more Se incorporation towards the replacement of Te. The dependence of Raman vibrational modes on excitation photon energy was investigated. As the excitation photon energy increases, three Raman vibrational modes (A_1g¹, E_g² and A_1g²) of the as-produced compounds move to low frequency. Three Infrared-active (IR-active) modes were observed in thin topological insulators (TIs) crystals.     

胃铋镁联合伊托必利治疗慢性胃炎消化不良症状的疗效分析

目的：观察胃铋镁与胃动力药伊托必利联合应用对慢性胃炎消化不良症状的疗效,为中西医结合治疗慢性胃炎提供临床依据。方法招募自2014年1月—2014年6月在厦门大学附属第一医院消化内科就诊的慢性胃炎伴消化不良患者116例,随机分为两组：对照组与观察组,各58例。对照组给予盐酸伊托必利50mg/次,3次/d,饭前30 min口服;观察组采用胃铋镁与伊托必利联合治疗,在对照组的基础上加服胃铋镁颗粒1袋/次,3次/d,饭后服用。两组疗程均为2周。观察记录治疗后两组患者的主要症状改善情况及其消失的时间,以及不良反应的发生情况。结果观察组患者消化不良症状改善的显效率为43.1%,总有效率为89.7%,分别优于对照组的20.7%和56.9%,差异具有统计学意义(P<0.05)。两组均未发生明显不良反应。结论胃铋镁与胃动力药联合治疗慢性胃炎合并消化不良的疗效优于单独应用胃动力药,临床疗效值得推广。     

Impact of Zr-Doped Bi2O3 Radiopacifier by Spray Pyrolysis on Mineral Trioxide Aggregate

Mineral trioxide aggregates (MTA) have been developed as a dental root repair material for a range of endodontics procedures. They contain a small amount of bismuth oxide (Bi₂O₃) as a radiopacifier to differentiate adjacent bone tissue on radiographs for endodontic surgery. However, the addition of Bi₂O₃ to MTA will increase porosity and lead to the deterioration of MTA’s mechanical properties. Besides, Bi₂O₃ can also increase the setting time of MTA. To improve upon the undesirable effects caused by Bi₂O₃ additives, we used zirconium ions (Zr) to substitute the bismuth ions (Bi) in the Bi₂O₃ compound. Here we demonstrate a new composition of Zr-doped Bi₂O₃ using spray pyrolysis, a technique for producing fine solid particles. The results showed that Zr ions were doped into the Bi₂O₃ compound, resulting in the phase of Bi_7.38Zr_0.62O_12.31. The results of materials analysis showed Bi₂O₃ with 15 mol % of Zr doping increased its radiopacity (5.16 ± 0.2 mm Al) and mechanical strength, compared to Bi₂O₃ and other ratios of Zr-doped Bi₂O₃. To our knowledge, this is the first study of fabrication and analysis of Zr-doped Bi₂O₃ radiopacifiers through the spray pyrolysis procedure. The study reveals that spray pyrolysis can be a new technique for preparing Zr-doped Bi₂O₃ radiopacifiers for future dental applications.     

Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

We investigated the anisotropic thermoelectric properties of the Bi₂Te_2.85Se_0.15I_x (x = 0.0, 0.1, 0.3, 0.5 mol.%) compounds, synthesized by ball-milling and hot-press sintering. The electrical conductivities of the Bi₂Te_2.85Se_0.15I_x were significantly improved by the increase of carrier concentration. The dominant electronic scattering mechanism was changed from the mixed (T ≤ 400 K) and ionization scattering (T ≥ 420 K) for pristine compound (x = 0.0) to the acoustic phonon scattering by the iodine doping. The Hall mobility was also enhanced with the increasing carrier concentration. The enhancement of Hall mobility was caused by the increase of the mean free path of the carrier from 10.8 to 17.7 nm by iodine doping, which was attributed to the reduction of point defects without the meaningful change of bandgap energy. From the electron diffraction patterns, a lattice distortion was observed in the iodine doped compounds. The modulation vector due to lattice distortion increased with increasing iodine concentration, indicating the shorter range lattice distortion in real space for the higher iodine concentration. The bipolar thermal conductivity was suppressed, and the effective masses were increased by iodine doping. It suggests that the iodine doping minimizes the ionization scattering giving rise to the suppression of the bipolar diffusion effect, due to the prohibition of the Bi_Te1 antisite defect, and induces the lattice distortion which decreases lattice thermal conductivity, resulting in the enhancement of thermoelectric performance.     

Phonon Scattering and Suppression of Bipolar Effect in MgO/VO2 Nanoparticle Dispersed p-Type Bi0.5Sb1.5Te3 Composites

Bismuth-Telluride-based compounds are unique materials for thermoelectric cooling applications. Because Bi₂Te₃ is a narrow gap semiconductor, the bipolar diffusion effect is a critical issue to enhance thermoelectric performance. Here, we report the significant reduction of thermal conductivity by decreasing lattice and bipolar thermal conductivity in extrinsic phase mixing of MgO and VO₂ nanoparticles in Bi_0.5Sb_1.5Te₃ (BST) bulk matrix. When we separate the thermal conductivity by electronic κel, lattice κlat, and bipolar κbi thermal conductivities, all the contributions in thermal conductivities are decreased with increasing the concentration of oxide particle distribution, indicating the effective phonon scattering with an asymmetric scattering of carriers. The reduction of thermal conductivity affects the improvement of the ZT values. Even though significant carrier filtering effect is not observed in the oxide bulk composites due to micro-meter size agglomeration of particles, the interface between oxide and bulk matrix scatters carriers giving rise to the increase of the Seebeck coefficient and electrical resistivity. Therefore, we suggest the extrinsic phase mixing of nanoparticles decreases lattice and bipolar thermal conductivity, resulting in the enhancement of thermoelectric performance over a wide temperature range.