全无机钙钛矿量子点的疏水改性及LED应用——推荐一个本科生综合化学实验

介绍一个综合化学实验——全无机钙钛矿量子点的疏水改性及LED应用。我们以三甲基氯硅烷和莫来石纤维增强SiO_(2)气凝胶的疏水性和韧性,获得疏水SiO_(2)气凝胶,随后以该疏水SiO_(2)气凝胶吸附全无机钙钛矿量子点形成CsPbX_(3)@SiO_(2)气凝胶复合材料。通过接触角、红外光谱、X射线衍射等表征手段证实SiO_(2)气凝胶的成功改性,并制作了LED器件。本实验涉及材料的合成、表征和应用,可作为化学和应用化学专业学生的综合化学实验,有助于提高学生的科学素养,激发对科学研究的兴趣。

Coupled simulation of fluid-particle interaction for large complex granules:A resolved CFD-DEM method for modelling the airflow in a vertical fixed bed of irregular sinter particles

A resolved CFD-DEM method is proposed to simulate the fluid-particle interaction for large complex granules.The airflow in a vertical sinter fixed bed is numerically studied using this method.The multi-sphere clumped method is used to create irregular sinter particles in DEM.The immersed boundary method and dynamic cell refinement are applied to describe the fluid flow around particles with higher resolution,by which the fluid-particle interaction can be simulated more accurately.The simulation results presented the packing voidage distributions and the airflow fields in the sinter beds of different single and mixed particle size ranges.The bed pressure drops were simulated and the results were compared with the corresponding experimental ones.The good agreement indicated that the proposed resolved CFD-DEM method is an effective tool to model the fluid-particle interaction for irregular large granules in the gas-solid multi-phase systems.

Petrogenesis, geochemistry and geological significance of Paleocene Granite in South Gangdese, Tibet

The Gangdese magmatic belt,located along the southern margin of the Lhasa terrane,plays a critical role in understanding the tectonic framework associated with the Indian-Asian slab collision.In this paper,a chronology of zircon U-Pb and geochemical analysis of the rock of the Cuobulaguo granitic mass in the southern of the Gangdese,Tibet,revealed a series of results.The results show that the LA-ICP-MS monzonitic granite zircon U-Pb ages are 61-59 Ma,which corresponds to the same period as the magmatic arc of the southern limit of Gangdese.In terms of geochemical composition,the granite is rich inω(SiO2)70.09%to 72.64%,with a highω(Al2O3)14.40%to 15.99%,a lowω(TiO2)0.08%to 0.24%,ω(MgO)0.41%to 0.76%,ω(Fe2O)6.82%to 29.9%,ω(P2Os)0.07%to 0.12%,andω(CaO)1.06%to 1.75%.The granite mainly belongs to the high-K calc-alkaline series.The light rare earth element(LREE)content of skeletal granite is between 133.69×10^-6〜226.64×10^-6 and the heavy rare earth element(HREE)content is between 17.36×10^-6 and 32.11×10^-6.LREE/HREE is between 5.05 and 7.83.It is enriched in light rare earth elements(LREE)and large ion lithophile elements,such as Rb,K,U,etc.,depletes high field strength elements,such as P,Nb,and Ta,and has the geochemical composition of arc magmatic rocks.In addition,the aluminum saturation index(A/CNK=1.06 to 1.11)of Cuobulaguo granite,belongs toⅠ-type granite.The comprehensive analysis showed that with the beginning of the collision between the Indian-Asian continental,the subduction ocean plate was separated from the continental plate due to gravity,resulting in an increase in the asthenosphere,which made partial fusion of the lithospheric mantle.It invaded the bottom of the lower crust,which in turn induced a partial melting of the lower crust to form granite.

Fine controllable blue emission and its mechanism in Ce^(3+)-doped orthosilicate solid solution phosphors for different plant growths

The designed Ce^3＋-doped alkaline-earth silicate phosphors CamSr2 m-nBanSiO4：Ce^3＋,Li^＋ （CSBS：Ce^3＋） were synthesized by a high temperature solid-state reaction. The crystal field splitting and the centroid shift from the flee ion energy of 5d configuration were approximated from the spectrum for Ca2SiO4, Sr2SiO4 and Ba2SiO4 phosphors. The single-phase purity was checked by means of X-ray diffraction. Here, when the doped concentration of Ca2. is less than 80% （m 〈 1.6）, we report the structural phase transformation from monoclinic system [3-Ca2Si04 to orthorhombic system α′-Ca2SiO4. The phosphors excited by near-ultraviolet （NUV） light at wavelengths ranging from 200 to 400 nm demonstrate a broad asymmetric blue emission band. The emission peak wavelength redshifts firstly from 417 nm of Ca2SiO4 to 438 nm of Sro.3Cal.6SiO4, and then blueshifts to 411 nm of Sr2SiO4, and the end of 401 nm of Ba2SiOa. These results indicate that the tunable blue-emission of the phosphors can he realized through changing the solid solution components, which has a potential use as a blue component for fabricated precision modulation LEDs light sources and auxiliaries of SSC plastics films for different plant growths. We discuss in detail the possible mechanism and energy diagram of the tunable blue luminescence in CamSr2-M-nBaNSiO4：Ce^3＋.Li^＋ phosphors.

To tune europium valence by controlling the composition in diphase silicate phosphors

Commercial phosphors always require fewer impurities and higher crystallinity, but sometimes it is difficult or strict to synthesize a pure phase compound. Indeed, if the practical application is not influenced, it is acceptable to synthesize a kind of phosphors with diphase matrix that have similar structure and photoluminescence properties. In present work, we designed and synthesized a series of（1-x）BaMSiO4·xBa2 MSi2 O7：Eu（M = Zn2＋, Mg2＋） diphase phosphors which contained two phases BaMSiO4（hexagonal, P63） and Ba2 MSi2 O7（monoclinic, C2/c） by a high temperature solid-state reaction in air condition. The structures and luminescence properties related to the phase transform from BaMSiO4 to Ba2 MSi2 O7 were analyzed carefully. The results show that the self-reduction ability of Eu3＋ is not the best in above four compounds, respectively. But it reaches the maximum and gets the green emission under the UV lamp when the matrix is in a proper ratio of two phases, which suggests that the heterostructure between the two crystals（BaMSiO4 and Ba2 MSi2 O7） improves the self-reduction process of the diphase.The possible mechanism of the tunable europium valence and the luminescent properties in（1-x）BaMSiO4·xBa2 MSi2 O7：Eu phosphors were discussed in detail.

Multiple regression analysis of the craniofacial region of Chinese Han people using linear and angular measurements based on MRI

The purpose of this study was to measure the craniofacial region of Chinese Han people in the linear and angular dimensions,and to analyse the effects on sex,age and body parameters(height and weight).All 250 individuals(86 males,164 females)underwent a three-dimensional magnetic resonance imaging(MRI)scan,and the MRI data were imported into VG Studio MAX 2.2 software.Each linear and angular measurement in the craniofacial region was processed directly.Using SPSS 20.0 software,nine multiple regression equations were constructed,and all the adjusted R^(2) values were statistically significant(0.031-0.311).Multiple regression analysis showed that most craniofacial measurements of Chinese people were significantly correlated with height,weight or age.The multiple regression equations constructed will be helpful in anthropometric analysis and forensic inference.

Research progress in the estimation of the postmortem interval by Chinese forensic scholars

The determination of time since death or the postmortem interval(PMI)is one of the most important and frequently asked questions in forensic medicine.Medicolegal scholars and forensic pathologists around the world have studied the estimation of PMI extensively in the past,and many novel methods and advanced technologies have now been applied in the field.For several centuries,Chinese forensic examiners have also worked on the estimation of the PMI,and there are a large number of excellent studies published in Chinese rather than in English,and these are not easily accessible or known internationally.Therefore we have conducted a review of relevant studies published by Chinese forensic scholars in the last few decades.The scope of this review is to provide a concise summary of the current progress in the estimation of PMI by Chinese forensic researchers using molecular biology,spectroscopic technology,entomological methods,energy changes,thanatochemistry and other methods.