Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.     

Dose verification of volumetric modulation arc therapy by using a NIPAM gel dosimeter combined with a parallel-beam optical computed tomography scanner

Volumetric modulated arc therapy (VMAT) was developed to shorten treatment time and increase target conformance. However, a true three-dimensional (3D) gel dosimeter is needed for dose verification. In this study, two clinic cases were adopted: a simple case of lung cancer and a complex case of larynx cancer. For each clinic case, two treatment plans were generated for the same planning target volume using VMAT and intensity modulated radiation therapy calculation software packages. An N-isopropylacrylamide (NIPAM) polymer gel dosimeter was used for 3D dose verification. In addition, the dose characteristics of the NIPAM gel dosimeter were investigated for the two clinic cases.

     

晶粒尺寸对Ba0.70Sr0.30TiO3陶瓷介电性能的影响规律及机理研究

通过制备晶粒尺寸处于0.1-10 μm之间的致密Ba0.70Sr0.30TiO3陶瓷,系统研究了晶粒尺寸对居里温度TC、铁电相介电常数εF、峰值介电常数εM的影响规律,并深入分析了其内在的影响机理.研究表明:晶粒尺寸减小时,TC刚开始基本不变,直到晶粒尺寸小到一定程度时才开始降低,此变化规律可由Buesseum的内应力模型解释;随晶粒尺寸的增加,εF先增加后减小,此变化规律可由Shaikh的串并联模型来解释,主要影响因素有内应力、畴、晶界;εM随晶粒尺寸的增加,在晶粒尺寸较小时先增加后减小,晶粒尺寸较大时略有增加,此变化规律可由弥散相变理论和串并联模型共同解释,在晶粒尺寸较小时主要影响因素为内应力、微畴和晶界,晶粒尺寸较大时主要影响因素为晶界.     

InGaAs/GaAs saturable absorber for diode-pumped passively Q-switched mode-locking of Tm:YAP laser

A passively Q-switched mode-locking of diode-pumped TmYAP laser by use of InGaAs/GaAs as a saturable absorber is reported. The maximum Q-switched mode-locking output power was 480 mW near the wavelength range of 1.94 μm with pulse repetition frequency of 26.47 kHz. The beam quality was also measured to be 1.12 ± 0.02.     

Synthesis of ZnO Photocatalysts Using Various Surfactants

Russian Journal of Physical Chemistry A - Zinc oxide (ZnO) nanostructured materials have received significant attention because of their unique physicochemical and electronic properties. In...     

Chemical composition of PM_(2.5) during winter in Tianjin,China

PM2.5 samples for 24 h were collected during winter in Tianjin,China. The ambient mass concentration and chemical composition of the PM2.5 were determined. Ionic species were analyzed by ion chromatog-raphy,while carbonaceous species were determined with the IMPROVE thermal optical reectance(TOR) method,and inorganic elements were measured by inductively coupled plasma-atomic emission spec-trometer. The daily PM2.5 mass concentrations ranged from 48.2 to 319.2 g/m3 with an arithmetic average of 144.6 g/m3. ...     

Upgrade of algebraic structure of ring

In order to construct nonregular power rings, the concept of regular semi-ideal with respect to a subring is introduced. Then several constructive theorems of HX ring and power ring are established and some examples of non-regular power rings are constructed which contain some nonregular HX rings.     

Highly Efficient Trityl-Nitroxide Biradicals for Biomolecular High-Field Dynamic Nuclear Polarization

Dynamic nuclear polarization (DNP) is a powerful method to enhance the sensitivity of solid-state magnetic nuclear resonance (ssNMR) spectroscopy. However, its biomolecular applications at high magnetic fields (preferably>14 T) have so far been limited by the intrinsically low efficiency of polarizing agents and sample preparation aspects. Herein, we report a new class of trityl-nitroxide biradicals, dubbed SNAPols that combine high DNP efficiency with greatly enhanced hydrophilicity. SNAPol-1, the best compound in the series, shows DNP enhancement factors at 18.8 T of more than 100 in small molecules and globular proteins and also exhibits strong DNP enhancements in membrane proteins and cellular preparations. By integrating optimal sensitivity and high resolution, we expect widespread applications of this new polarizing agent in high-field DNP/ssNMR spectroscopy, especially for complex biomolecules.     

NMR studies on 4‐thio‐5‐furan‐modified and 4‐thio‐5‐thiophene‐modified nucleosides

Systematic NMR characterization of 4‐thio‐5‐furan‐pyrimidine nucleosides or 4‐thio‐5‐thiophene‐pyrimidine nucleosides (ribonucleosides and 2′‐deoxynucleosides) was performed. All proton and carbon signals of 4‐thio‐5‐thiophene‐ribouridine and related analogues were unambiguously assigned. The orientations of the base (4‐thiouridine or its deoxy analogue) relative to the ring (furan or thiophene) are explored by a NMR approach and further supported by X‐ray crystallographic studies. The procedures presented here would be applicable to other modified nucleosides and nucleotides. Copyright © 2016 John Wiley & Sons, Ltd.