分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Based on a bio-inspiration polydopamine reaction platform, hollow Ag/carbon microporous spheres were facilely prepared through a template-assisted method. The hollow Ag/carbon spheres, with a uniform shell thickness of 30 nm and a high Ag loading, show high catalytic activity for the reduction of 4-nitrophenol by NaBH4 to 4-aminophenol. It is found that the 4-nitrophenol (10 mL, 1 10 3 M) can be completely converted to 4-aminophenol in 2 min by adding 20 mg of hollow Ag/carbon catalysts. The catalytic activity of the hollow Ag/carbon microporous spheres is also confirmed by CO oxidation. At 200 C, 100% CO conversions can be achieved by using hollow Ag/carbon microporous spheres as catalysts, which is promising to replace other noble metal catalysts in metal catalyzed reactions.
分类: 生物学 >> 生物学其他学科 提交时间: 2018-12-04 合作期刊: 《古脊椎动物学报》
摘要: A cervical vertebra recovered from the Middle Jurassic Lower Member of the Shaximiao Formation in Town of Puan, Yunyang County, Chongqing is assigned to an species undeterminata of the sauropod dinosaur Omeisaurus based on morphological and comparative study. The centrum of this mid-cervical is much hollower than solider with extremely developed fossa/foramen complex and has a high ratio (5.05) of its anteroposterior length excluding the articular ball divided by the mean value of the posterior articular surface mediolateral width and dorsoventral height. Additional features of this cervical include central length about twice the total vertebral height, a prominent midline keel on the central ventral surface, deep and long cavities bounded by centroprezygapophyseal lamina/ intraprezygapophyseal lamina and centropostzygapophyseal lamina/intrapostzygapophyseal lamina, respectively, a coel on the dorsal half of the postzygapophyseal centrodiapophyseal fossa, long prone epipophysis extending beyond the postzygapophysis facet, anteroposteriorly length of the neural spine about half the length of the centrum, and concavities on the anterior one third lateral surface of the neural spine. Therefore, this discovery reveals new morphological information on Omeisaurus, and this Omeisaurus-bearing Puan dinosaur quarry represents the easternmost occurrence of this genus.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: The preparation of lightweight materials with electromagnetic interference-shielding effect- iveness higher than 30dB is critical for most industrial and consumer applications. Compounding polymer resin with conductive filler can generate excellent electromagnetic interference-shielding effectiveness but usually leads to a high-sample density, while the foaming of polymer composite suffers from the significant-reduced electromagnetic inter- ference-shielding effectiveness. In this study, polyetherimide composite foams with loading of 10–80 phr (parts per hundred of resins) nickel particles were fabricated to meet the gap. The polyetherimide/nickel composite foams possessed uniform cell structure and low- sample density such as 0.86 g/cm3 at 70 phr nickel. The coupling effects of gravity settle- ment and cell-structure solidification led to the formation of gradient distribution of nickel particles across the foams. The formed novel structure facilitated the enhancement of multi-reflection and multi-scattering among nickel particles and cells. As a consequence, polyetherimide/nickel foam with 70 phr nickel (PEIN70) possessed a high-electromagnetic interference shielding effectiveness of 86.7–106.5 dB over a frequency range of 50–3000MHz. When the sample density was considered, the specific electromagnetic interference shielding effectiveness of PEIN70 foam was as high as 121.3 dB/(g/cm3) at 1 GHz, which was higher than the reported electromagnetic interference-shielding materials. The excellent electromagnetic interference-shielding properties, lightweight, well-defined resin proper- ties ensure polyetherimide/nickel composite foams useful in many advanced applications.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Many chemotherapeutics used for cancer treatments encounter issues during delivery to tumors in vivo and have high levels of systemic toxicity. One of the most prominent progresses in improving drug delivery efficiency is through exploring various types of nanoparticles (NPs) as drug carriers. Recent studies have demonstrated that titanium dioxide (TiO2) nanocarriers have potential for drug delivery and therapy even in multidrug resistant cancers in vitro. Moreover, it was proved that the anticancer activity of doxorubicin (DOX) was enhanced by loading onto TiO2 nanoparticles in breast cancer cells in vitro. However, there is no evidence from the animal model in vivo, which is a critical step for their further clinical applications. The aim of this study was to explore novel TiO2–PEG–DOX nanoparticles, the DOX loaded polyethylene glycol (PEG) coated TiO2 nanocarriers, and investigate their potential application in enabling controlled drug release and enhancing the chemotherapeutic efficacy of DOX in the orthotopic breast tumor bearing mice. The tumor growth and drug treatment efficacy were dynamically monitored by bioluminescence imaging (BLI), and the safety of NPs for in vivo usage was also evaluated. It was found that TiO2–PEG–DOX nanoparticles possessed improved antitumor efficacy without observable side effects compared to the free DOX treatment. Our study suggested that the PEG coated TiO2 nanocarrier is a safe and potential platform for the efficient drug delivery and minimizing the systemic toxicity of chemotherapeutic agents. It has been proved for the first time that TiO2-based nanocarriers enhance the chemotherapeutic effects of doxorubicin in vivo.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A green facile scalable method inspired by polymeric dental restorative composite is developed to synthesize TiO2/carbon nanocomposites for manipulation of the intercala- tion potential of TiO2 as lithium-ion battery anode. Poorly crystallized TiO2 nanoparticles with average sizes of 4−6 nm are homogeneously embedded in carbon matrix with the TiO2 mass content varied between 28 and 65%. Characteristic discharge/ charge plateaus of TiO2 are significantly diminished and voltage continues to change along with proceeding discharge/charge process. The tap density, gravimetric and volumetric capacities, and cyclic and rate performance of the TiO2/C composites are effectively improved.