Vibrational spectroscopy in the development of surface hydrophilic elastomer latex (SHEL)

An illustrative example is given to show how various vibrational spectroscopy techniques coupled with two-dimensional (2D) correlation analysis can be effectively utilized in the development of a novel and functional material. Surface-hydrophilic elastomer latex (SHEL) is a material exhibiting rather unusual permanently water-wettable surface feature despite having a soft and rubbery bulk property, which can be successfully analyzed with vibrational spectroscopy. 2D photoacoustic (PAS) IR spectra of a SHEL film indicate the localized surface segregation of long-chain ethoxylate moiety of the oligomeric surfactant used in the preparation of this material. The accumulation of the hydrophilic long-chain ethoxylate produces the high energy polar surface over the hydrophobic bulk phase of SBR copolymer. The persistence of very low water contact angle, even after repeated washing of a SHEL film with an excess amount of water, indicates permanent covalent attachment of long-chain ethoxylate group to the SBR copolymer. 2D Raman spectra generated from the process monitoring of the emulsion copolymerization of SHEL reveal the mechanism of the covalent attachment of long-chain ethoxylate. The reaction involves a separate step of oleyl moiety of the block surfactant reacting with 1,3-butadiene prior to the onset of copolymerization to produce the SBR latex product.     

基于COLLATE融合多图谱的心脏电影MRI右心室分割

右心室分割对肺动脉高压等疾病的心功能分析具有重要的临床意义.然而，右心室心肌薄、易变且不规则，其传统的医学图像分割方法仍然未能取得突破性进展.本文提出基于COLLATE（Consensus Level，Labeler Accuracy and Truth Estimation）的多图谱分割方法，首先以归一化互信息为相似测度对目标图像和图谱集进行B样条配准以获取粗分割结果；然后利用COLLATE对粗分割结果进行融合；最后采用基于形状约束的区域生长算法修正出现错误的数据.10例临床心脏磁共振短轴电影图像被用于算法验证.本文还将使用基于COLLATE的多图谱分割方法得到的结果与深度学习算法及手动分割进行了比较.结果显示与深度学习算法比较，使用本文算法得到的射血分数（Ejection Fraction，EF）与手动分割更加一致和相关，表明该算法的分割结果有望辅助临床心脏功能诊断.     

A field-reversal method for measuring the parameters of a ferroelectric liquid crystal

A method for measuring the spontaneous polarization P _s, the switching time, the rotational viscosity γ_φ, and the d.c. conductivity σ is presented. The possibilities of estimating the azimuthal angle φ₀, the dielectric anisotropy δε and the dielectric permittivity ε_⊥ in the same experiment are also discussed. It is explicitly shown that the switching delay, though primarily dependent on the material and the applied field, is also dependent on the geometry of the cell.     

超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量

采用电磁场有限元方法,数值模拟了孔径型扫描近场光学显微镜(aperture Scanning Near-field Optical Microscopy,a-SNOM)在照明模式下的工作过程.针对金偶极天线结构,改变天线长度和纳米间隙尺寸,计算了a-SNOM探针孔径的远场辐射速率随探针端面中心坐标变化的扫描曲线,实现了超越a-SNOM探针通光孔径尺寸的天线金属纳米间隙的超分辨测量,对于100nm通光孔径的探针,可分辨最小尺寸为10nm(0.016倍波长)的金属间隙.通过对比金属和介质偶极天线的a-SNOM探针远场辐射速率测量的计算结果,表明天线金属纳米间隙的超分辨测量的实现是由于金属间隙表面等离激元的激发.     

Purification of low-abundance lysozyme in egg white via free-flow electrophoresis with gel-filtration chromatography

As an effective separation tool, free-flow electrophoresis has not been used for purification of low-abundance protein in complex sample matrix. Herein, lysozyme in complex egg white matrix was chosen as the model protein for demonstrating the purification of low-content peptide via an FFE coupled with gel fitration chromatography (GFC). The crude lysozyme in egg while was first separated via free-flow zone electrophoresis (FFZE). After that, the fractions with lysozyme activity were condensed via lyophilization. Thereafter, the condensed fractions were further purified via a GFC of Sephadex G50. In all of the experiments, a special poly(acrylamide- co-acrylic acid) (P(AM-co-AA)) gel electrophoresis and a mass spectrometry were used for identification of lysozyme. The conditions of FFZE were optimized as follows: 130 μL/min sample flow rate, 4.9 mL/min background buffer of 20 mM pH 5.5 Tris-Acetic acid, 350 V, and 14 °C as well as 2 mg/mL protein content of crude sample. It was found that the purified lysozyme had the purity of 80% and high activity as compared with its crude sample with only 1.4% content and undetectable activity. The recoveries in the first and second separative steps were 65% and 82%, respectively, and the total recovery was about 53.3%. The reasons of low recovery might be induced by diffusion of lysozyme out off P(AM-co-AA) gel and co-removing of high-abundance egg ovalbumin. All these results indicated FFE could be used as alternative tool for purification of target solute with low abundance.     

CdBiO2NO3, a new layered bismuth oxide nitrate

Step-wise reaction of CdO, Bi₂O₃, and Cd(NO₃)₂^·4H₂O leads to formation of a novel bismuth oxide nitrate, CdBiO₂NO₃, which completes the family of bismuthite-like M^IIBiO₂NO₃ oxide nitrates. The new compound is tetragonal, I4/mmm, a = 3.9486(1)Å, c = 14.2235(2)Å; its crystal structure resembles those of PbBiO₂NO₃ and CaBiO₂NO₃, except for, probably, different positioning of the nitrate group. The compound is stable until ∼425 °C when it decomposes, in one step, into CdO and a mixture of Bi–Cd oxides. Cd-based analogs of isostructural PbLnO₂NO₃ (Ln – lanthanides) oxide nitrates are unlikely to exist. We discuss the similarities and differences in the structures of layered oxyhalides and oxynitrates of bismuth and rare-earths.     

Experimental study and thermodynamic modeling of the MgO–NiO–SiO2 system

The MgO–NiO–SiO₂ system has been studied by a combination of thermodynamic modeling and experimental measurements of phase equilibria. A complete literature review, critical evaluation and thermodynamic modeling of phase diagrams and thermodynamic properties of all oxide phases in the MgO–NiO–SiO₂ system at 1 atm total pressure are presented. To resolve the contradictions in the literature data, a new experimental investigation has been carried out over the temperature range from (1400 to 1650) °C using an equilibration and quenching technique followed by electron probe X-ray microanalysis (EPMA). Tie-lines between olivine and monoxide, olivine and proto-pyroxene, liquid and olivine and liquid and cristobalite have been measured. The whole set of experimental data, including the new experimental results and previously published data, has been taken into consideration in thermodynamic modeling of oxide phases in the MgO–NiO–SiO₂ system. The Modified Quasichemical Model has been used for the liquid phase. A simple random mixing model with a polynomial expansion of the excess Gibbs energy has been used for the monoxide solid solution. The models for olivine and proto-pyroxene were developed within the framework of the Compound Energy Formalism. The optimized model parameters reproduce all available thermodynamic and phase diagram data within experimental error limits.     

Copper-containing dendromesogens: the influence of the metal on the mesomorphism

The synthesis and liquid crystalline behaviour of the first and second generations of a dendrimeric structure based on poly(propyleneimine)(DAB-dendr(NH₂)_x) are reported. 4-(4-n-Alkoxybenzoyloxy)salicylaldehydes are used as mesogenic moieties attached at the peripheral amino groups of the dendrimers giving rise to dendromesogens with four and eight mesogenic branches. From these dendromesogens, considered as organic ligands, were prepared six metal-containing dendrimers which incorporate two or four copper atoms in their structures. All the dendrimeric ligands and three of the metal-containing dendrimers exhibit liquid crystalline properties which were studied by optical microscopy, DSC, X-ray diffraction and EPR spectroscopy.     

A microfluidic surface-enhanced Raman scattering (SERS) sensor for microRNA in extracellular vesicles with nucleic acid-tyramine cascade amplification

Exosomal microRNA (miRNA) is an ideal candidate of noninvasive biomarker for the early diagnosis of cancer. Sensitive and accurate sensing of abnormal exosomal miRNA plays essential role for clinical promotion due to its close correlation with tumor proliferation and progression. Herein, a microfluidic surface-enhanced Raman scattering (SERS) sensor was proposed for an on-line detection of exosomal miRNA based on rolling circle amplification (RCA) and tyramine signal amplification (TSA) strategy. The microfluidic chip consists of a magnetic enrichment chamber, a serpentine fluidic mixer and a plasmonic SERS substrate functionalized with capture probes. The released miRNA activates the capture probe, triggers RCA reaction, and generates a large number of single-stranded DNA products to drive the catalysis of nanotags deposition via TSA, producing numerous “hot spots” to enhance the SERS signals. In merit of the microfluidics chip and nucleic acid-tyramine cascade amplification, the developed SERS sensor significantly improves the sensitivity for the exosomal miRNA assay, resulting in a limit of detection (LOD) as low as 1 pmol/L and can be successfully applied in the analysis of exosomes secreted from breast tumor cells, which demonstrates the potential utility in practical applications.     

Design of hierarchical and mesoporous FeF3/rGO hybrids as cathodes for superior lithium-ion batteries

Iron fluoride (FeF₃) is considered as a promising cathode material for Li-ion batteries (LIBs) due to its high theoretical capacity (712 mAh/g) with a 3e^? transfer. Herein, we have designed a strategy of hierarchical and mesoporous FeF₃/rGO hybrids for LIBs, where the hollow FeF₃ nanospheres are the main contributor to the specific capacity and the 2D rGO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion. The unique FeF₃/rGO hybrid can be rationally synthesized by a non-aqueous in-situ precipitation method, offering the merits of large specific surface area with rich active sites, fast transport channels for lithium ions, effective alleviation of volume expansion during cycles, and accelerating the electrochemical reaction kinetics. The FeF₃/rGO hybrid electrode possesses a high initial discharge capacity of 553.9 mAh/g at a rate of 0.5 C with 378 mAh/g after 100 cycles, acceptable rate capability with 168 mAh/g at 2 C, and feasible high-temperature operation (320 mAh/g at 70 °C). The superior electrochemical behaviors presented here demonstrates that the FeF₃/rGO hybrid is a potential electrode for LIBs, which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.