Crystallization behavior and thermal properties of blends of poly(3-hydroxybutyate-co-3-valerate) and poly(1,2-propandiolcarbonate)

Crystallization behavior of blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(1,2-propandiolcarbonate) (PR(CO₂)) has been investigated by polarized light microscopy (PLM). The spherulite growth rates (SGR) of all blends were faster than that of pure PHBV, and the spherulite growth rates of PHBV in the PHBV/PR(CO₂) blends reduced with increasing PR(CO₂) weight fraction. There are two melting peaks in both the pure PHBV and the PHBV/PR(CO₂) blends. The melting peak of PHBV/PR(CO₂) blends was reduced by lower temperature about 20K as compared to PHBV and the higher temperature melting peak was increased by about 10K in the blends.     

Anionic Sublattices in Halide Solid Electrolytes: A Case Study with the High-Pressure Phase of Li3ScCl6

The Li₃MX₆ compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li₃ScCl₆ using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P6₃mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li₃ScCl₆ and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li₃MX₆ family further revealed that the cation/anion radius ratio, r_M/r_X, is the factor that determines which anion sublattice is formed and that in γ-Li₃ScCl₆, the difference in compressibility between Sc and Cl exceeds the ccp r_M/r_X threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li₃ScCl₆ demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings.     

One-Pot Facile Synthesis of Noble Metal Nanoparticles Supported on rGO with Enhanced Catalytic Performance for 4-Nitrophenol Reduction

In this study, reduced graphene oxide (rGO)-supported noble metal (gold, silver, and platinum) nanoparticle catalysts were prepared via the one-pot facile co-reduction technique. Various measurement techniques were used to investigate the structures and properties of the catalysts. The relative intensity ratios of I_D/I_G in rGO/Au, rGO/Ag, rGO/Pt, and GO were 1.106, 1.078, 1.047, and 0.863, respectively. The results showed the formation of rGO and that noble metal nanoparticles were decorated on rGO. Furthermore, the catalytic activities of the designed nanocomposites were investigated via 4-nitrophenol. The catalysts were used in 4-nitrophenol reduction. The catalytic performance of the catalysts was evaluated using the apparent rate constant k values. The k value of rGO/Au was 0.618 min⁻¹, which was higher than those of rGO/Ag (0.55 min⁻¹) and rGO/Pt (0.038 min⁻¹). The result proved that the rGO/Au catalyst exhibited a higher catalytic performance than the rGO/Ag catalyst and the rGO/Pt catalyst. The results provide a facile method for the synthesis of rGO-supported nanomaterials in catalysis.     

主动中子多重性铀质量测量模拟研究

中子多重性技术常用于测量和核查核材料,尤其针对具有较厚屏蔽的对象具有不可替代的优势。钚的自发裂变率较高,可以采用被动测量方法,目前已有多款不同的测量装置。然而铀材料的自发裂变率较低只能采用主动测量方法。现有的主动井型符合计数器（AWCC）能够进行主动中子多重性测量铀材料质量,但依然存在探测效率较低,Am-Li中子源产生偶然符合大等缺点。为提高铀材料测量的效率和精度,对主动中子多重性测量方法开展深入研究非常必要。本文参考AWCC模型,利用Geant4软件对探测器和粒子的输运过程进行建模。研究了多重性移位寄存器的不同符合门宽、不同延迟时间对铀测量结果相对偏差的影响规律。计数器的最佳门宽为44 μs,门宽取值范围在计数器衰减时间的1.5倍左右合适;延迟时间大于3倍计数器衰减时间后,相对偏差显著减少。最后讨论了235U富集度变化对主动中子多重性测量结果的影响。为后续主动中子多重性铀质量测量仪器的设计提供了参考。     

数字状张拉整体结构的构型设计与力学性能模拟

针对大型张拉整体结构的设计问题,选取四棱柱状张拉整体结构和截角正八面体状张拉整体结构作为基本胞元,采用节点连接节点的方式建立球柱组合式数字状张拉整体结构,并使用基于结构刚度矩阵的大变形非线性数值求解方法对其进行力学性能分析.在两类胞元满足各自的自平衡条件和稳定性条件的前提下,组合得到的数字状张拉整体结构亦处于自平衡稳定状态,搭建了实物模型进行验证.以数字8状张拉整体结构为例,模拟研究了结构承受自重等分布载荷和单轴拉压等端部载荷时的静力学响应,以及结构无阻尼振动时的固有频率和模态等动力学性能.结果表明,结构在自重作用下的变形行为受初始预应力、压杆密度和拉索刚度的影响较大,对其进行合理配置方可确保结构具有足够刚度抵抗自重;结构在单轴拉压作用下呈现非线性的载荷-位移曲线,拉伸刚度随变形量的增大而增大,压缩刚度随变形量的增大而减小;结构的固有频率随初始预应力的增大而增大,而模态振型基本不变.研究结果丰富了大型张拉整体结构的外形种类,有望推动此类结构在土木建筑、结构材料等领域的应用.      

Azomethine-H as a Highly Selective Fluorescent Probe for Fe3+ Detection in 100％ Aqueous Solution and Its Application in Living Cell Imaging

A simple assay for the detection of Fe³⁺ in water by means of fluorescence spectroscopy was developed based on a commercially available reagent, Azomethine-H(A-H), allowing sensing trace levels of Fe³⁺ with high selectivity over other cations. A significant fluorescence quenching of A-H at 424 nm was found after its binding with Fe³⁺ in 100% aqueous solution at pH=7.0, while other physiologically relevant metal ions posed little interference. The fluorescence responses can be well described by the modified Stern-Volmer equation. A good linear relationship(R²=0.9904) was observed up to 1.6×10^-5 mol/L Fe³⁺ ions. The detection limit, calculated via the 3σ IUPAC(international union of pure and applied chemistry) criteria, was 1.95×10^-7 mol/L. Moreover, the colorimetric and fluorescent response of A-H to Fe³⁺ can be conveniently detected by the naked eye, providing a facile method for visual detection of Fe³⁺. The proposed method was used to determine Fe³⁺ in water samples. Moreover, inverted fluorescence microscopy imaging using human umbilical vein endothelial cells shows that A-H can be used as an effective fluorescent probe for detecting Fe³⁺ in living cells.     

A plasma frequency modulation model for constructing structure material with arbitrary cross-section thin metallic wires

Considering the fact that just the electrons confined in the region of the skin depth will actually affect the plasma frequency due to the skin effect, a model for constructing epsilon-near-zero (ENZ) metamaterials through the arranged thin metallic wires with arbitrary cross-section is developed, utilizing the perimeter approximation. With our model, plasma frequency can be freely modulated just by the variance of the metallic wire perimeter, irrespective of the cross-section shape of wires. The finite element method (FEM) and S-parameters retrieval method were employed to numerically simulate the plasma frequencies, which have verified the validity of the theoretical model.     

Source Apportionment Research of Fine Particulate Matter in the Atmosphere by PAHs

Haze weather frequently occurs in many cities in China. Polycyclic aromatic hydrocarbons(PAHs) in fine particulate matter(PM_2.5) can adversely affect the environment and human health. In this paper, PM_2.5 samples were collected at nine sites in a city in northeastern China from September 2013 to October 2014. Sixteen USEPA(US Evironment Protection Agency) priority PAHs in PM_2.5 were analyzed to determine their spatial and temporal distribution characteristics. The source apportionment of PAHs was conducted with the Positive Matrix Factorization(PMF) model. The results indicate that the concentrations of total PAHs(T-PAHs) in PM_2.5 are within the range of 0.26 to 72.48 ng/m³. The seasonal variation of T-PAHs is winter >spring >autumn >summer, and the space distribution of PAHs is JZP >DP >BFH >LP >EESA >IPT >CP >HZMC >JYP. In all types of PAHs, three-ring and five-ring PAHs are significantly prominent(62%) in the heating period due to petrogenic sources and traffic emissions. Middle- and high-ring PAHs in the non-heating period are caused by coal combustion and vehicle exhaust, which accounts for 77% of the total emissions. The source apportionment results obtained by the diagnostic ratio of PAHs reflect that coal burning, traffic and other sources have a distinct influence on PAH emissions in this city. Six factors are defined by PMF v5.0, namely, coke oven emissions(7.7%), biomass burning(44.3%), petrogenic sources(10.7%), coal combustion(10.4%), gasoline engine emissions(16.7%), and diesel engine emissions(10.3%). The results indicate that the PAHs in PM_2.5 in the city are primarily caused by combustion processes and vehicle exhaust.     

Structure–property relationship of hetero‐aromatic‐electron‐donor antennas of polypyridyl Ru (II) complexes for high efficiency dye‐sensitized solar cells

Three novel heteroleptic amphiphilic polypyridyl Ru‐complexes, coded MH08–10 , with hetero‐aromatic electron‐donor ancillary ligands containing N‐benzylcarbazole ( MH08 ), dibenzofurane ( MH09 ) and benzothiophene moieties ( MH10 ) were synthesized to study the influence of different heterocyclic electron donors on the interrelationship of photophysical and electrochemical properties, and device performances for dye‐sensitized solar cells (DSSCs). MH08 showed a remarkably high molar extinction coefficient of 27,650 M⁻¹cm⁻¹. MH08–TBA was synthesized from MH08 by converted one COOH group into −COO⁻⁺N(C₄H₉)₄ to investigate the effect of deprotonating one carboxylic group on the Fermi level and electron injection. When compared under the same experimental device conditions using 0.3M t‐butylpyridine (TBP), the short‐circuit photocurrent density (J_SC) and total conversion efficiency (%η) of MH08–10 were MH08 > MH09 > MH10 . The differences in %η and J_SC of MH08–10 were ascribed to the conjugation length coupled with the electron donation and hole‐transport strength of the ancillary ligands, which were in the following order N‐benzylcarbazole>dibenzofurane>benzothiophene. Moreover, MH08–TBA showed J_SC of 19.56 mAcm⁻² and %η of 9.76% compared to 17.16 mAcm⁻² and 9.12% of the benchmark dye N719 . The superior performance of MH08–TBA was attributed to its better light harvesting and enhanced incident‐photon‐to‐current efficiency (IPCE) conversion. DFT/TD‐DFT calculations utilizing the energy functional B3LYP and the full‐electron basis set DGDZVP were performed to calculate HOMO and LUMO energies, vertical electronic excitations, lowest singlet‐singlet electronic transitions (E_0‐0), and excited state oxidation potentials. Excellent agreement was found between the experimental results and calculated data. Copyright © 2013 John Wiley & Sons, Ltd.     

基于Flash Action Script的森林灭火系统火控软件的设计与实现

针对原有版本的森林灭火系统火控软件操作复杂、价格昂贵的缺点,提出了使用搭载安卓操作系统的平板电脑作为火控计算机,以Flash CS5为开发工具,ActionScript3.0为开发语言设计和实现了森林灭火系统火控软件。该软件可在搭载安卓操作系统的平板电脑上安装使用,具有操作简单、低成本的优势。