Chromium substituted copper ferrites via gluconate precursor route

CuFe_2−xCr_xO₄ spinel (0≤x≤2) powders were synthesized by a soft chemistry method—the gluconate multimetallic complex precursor route. The complex precursors were characterized by elemental chemical analysis, infrared (IR) and ultraviolet–visible (UV–vis) spectroscopy, thermal analysis and Mössbauer spectroscopy. The oxide powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), IR, Raman and Mössbauer spectroscopy. It was shown that the structure, morphology and magnetic properties of the obtained spinel powders depend on the concentration of Cr³⁺ ion. The XRD of the chromium substituted copper ferrite powders calcined at 700 °C/1 h indicated the formation of a cubic spinel type structure for x=0.5, 1.0 and a tetragonal structure for x=0, 0.2, 2. The crystallite size ranged from 19 nm to 39 nm. The Mössbauer spectroscopy revealed the site occupancy of iron ions, relative abundance and internal hyperfine magnetic fields in both tetrahedral and cubic CuFe_2−xCr_xO₄ spinels.     

羟基肉桂酸衍生物的合成及其与人血清白蛋白的相互作用

以咖啡酸、间羟基肉桂酸为母体,分别与止血芳酸反应,设计合成两种羟基肉桂酸衍生物I、II,并用MS、IR、1H-NMR、13C-NMR进行结构表征。采用荧光光谱法、同步荧光光谱法、紫外可见光谱法结合分子对接技术研究其在体外生理条件下与HSA之间的相互作用机制。光谱实验结果表明,衍生物I和II都可以使HSA的内源荧光发生静态猝灭,相互作用力主要是氢键和范德华力,且对HSA的构象产生一定的影响。分子对接结果表明衍生物I、II与HSA中的结合位于亚结构域IIA（即site I）中,作用力主要是氢键和范德华力,同时还存在着疏水作用,且衍生物距色氨酸残基(Trp214)很近,很好地解释了衍生物有效猝灭HSA内源荧光的实验现象。分子对接与实验获得了一致性的结果,二者相互作证,提高了实验结果推断的准确度。     

Transport Properties,Local Coordination,and Thermal Stability of the Water/Diethylmethylammonium Methanesulfonate Binary System

Ammonium based protic ionic liquids are highlighted for their great potential to sustain proton transport in proton exchange membrane (PEM) fuel cells. Yet, there remain questions concerning the effect of water produced by the fuel cell at the cathode side on the performance of the ionic liquid. In this contribution we report the effect of water on the transport properties and the local coordination in the binary system of the protic ionic liquid diethylmethylammonium methanesulfonate ([DEMA][OMs]) and water, employing ¹H NMR, Raman, and infrared spectroscopy. We observe that the self‐diffusion of cations and anions increases with the water content and that cations and anions diffuse at the same rate at all concentrations investigated. ¹H NMR and vibrational spectroscopy, on the other hand, indicate that added water interacts primarily with the anion and slightly affects the ionicity of the ionic liquid. In addition, by investigating the thermal stability of the binary system we find that although [DEMA][OMs] displays a continuous loss of water upon increasing temperature a fraction of water molecules can be retained even above 120 °C, and that the complete loss of water is immediately followed by decomposition, which is observed to occur at about 185 °C.     

Development of Whole and Ground Seed Near-Infrared Spectroscopy Calibrations for Oil,Protein, Moisture,and Fatty Acids in Salvia hispanica

Chia (Salvia hispanica) is an ancient crop that has experienced an agricultural resurgence in recent decades owing to the high omega 3 fatty acid (ω-3) content of the seeds and good production potential. Analysis of 563 lots of chia grown in Kentucky and 10 lots from Arizona, Australia, Mexico, and Peru was performed. All of these lots were assessed for fatty acid, oil, and protein content, while a subset of 120 samples were assessed for amino acids, fiber, minerals, and trace elements. The mean oil content was 31.3%, ranging from 21.4% to 35.3%. The protein content averaged 22.8%, ranging from 18.2% to 28.2%, and the ω-3 FA α-linolenic acid (ALA) averaged 61.3%, ranging from 33.9% to 69.9%. Using these seed lots, nondestructive near-infrared spectroscopy (NIRS) calibrations were developed for whole and ground seed oil, protein, moisture, and the six major fatty acids. The R² and SE of cross-validation (SECV) values for oil were 0.78 and 0.95, respectively, while those for protein were 0.75 and 1.05, respectively. The NIRS calibrations for fatty acid had R² and SECV greater than 0.6 and less than 10% of actual values for all major fatty acids, respectively. An R² of 0.99 was established for moisture content of whole seeds within the range of 3–10% moisture content. The precision and accuracy of these calibrations is adequate for use by breeders, growers, and food quality experts to quantitatively assess these major constituents without the need for costly and time-consuming chemical analysis.     

Trace level analysis of reactive ISO 14687 impurities in hydrogen fuel using laser-based spectroscopic detection methods

Hydrogen fuelled vehicles can play a key role in the decarbonisation of transport and reducing emissions. To ensure the durability of fuel cells, a specification has been developed (ISO 14687), setting upper limits to the amount fraction of a series of impurities. Demonstrating conformity with this standard requires demonstrating by measurement that the actual levels of the impurities are below the thresholds. Currently the industry is unable to do so, for measurement standards and sensitive dedicated analytical methods are lacking. In this work, we report on the development of such measurement standards and methods for four reactive components: formaldehyde, formic acid, hydrogen chloride and hydrogen fluoride. The primary measurement standard is based on permeation, and the analytical methods on highly sensitive and selective laser-based spectroscopic techniques. Relative expanded uncertainties at the ISO 14687 threshold level in hydrogen of 4% (formaldehyde), 8% (formic acid), 5% (hydrogen chloride), and 8% (hydrogen fluoride) have been achieved.     

Tetragonal pencil-like VO2(R) as electrode materials for high-performance redox activities

Pencil-like tetragonal vanadium dioxide has been synthesized via one-step hydrothermal treatment. The compounds were analyzed through X-ray powder diffraction; scanning electron microscope and X-ray photoelectron spectroscopy (XPS). The optical properties of the as-synthesized material were studied by UV–visible diffuse reflection spectroscopy and room temperature photoluminescence. Thin films of VO₂(R) deposited on ITO substrates were electrochemically characterized by cyclic voltammetry (CV). The voltammograms show a reversible redox behavior with a doping/dedoping process corresponding to reversible cation intercalation/de-intercalation into the crystal lattice of the pencil. This process is easier in propylene carbonate than in aqueous solvent. It is also easier for the small Li⁺ cation than larger ones, Na⁺ and K⁺. This is attributed to a probable presence of one tunnel cavities in the structure of VO₂(R). The good electrochemical property of the VO₂(R) is attributed to its unique ultralong nanopencils structure with a good structural stability.     

Large-scale synthesis of WO3 nanoplates by a microwave-hydrothermal method

Tungsten oxide (WO₃) nanoplates were synthesized by a 270 W microwave-hydrothermal reaction of Na₂WO₄·2H₂O and citric acid (C₆H₈O₇·H₂O) in deionized water. X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) were used to reveal the synthesis of WO₃ complete rectangular nanoplates in the solution of 0.2 g citric acid for 180 min, with O-W-O FTIR stretching modes at 819 and 741 cm⁻¹, and two prominent O-W-O Raman stretching modes at 804 and 713 cm⁻¹. The 2.71 eV indirect energy gap, and 430-460 nm blue emission wavelength range of WO₃ complete rectangular nanoplates were determined using UV-visible and photoluminescence (PL) spectrometers. The formation mechanism was also proposed according to the experimental results.     

《波谱解析》课程教学方法探讨

波谱解析是化学和药学专业一门重要的课程,在以往的教学过程中发现,学生难学,老师难教是该课程的一大特点。根据当前高等院校波谱解析课程教学过程中存在的问题,本文分别从教学方法,教学实践和考核方法等方面提出了一些具体的改革措施。     

Molecular mobility in a homologous series of amorphous solid glucose oligomers

The molecular mobility of amorphous solid biomaterials influences the stability of dried foods and pharmaceuticals, the viability of seeds and spores, and the desiccation-tolerance of organisms during anhydrobiosis. Current understanding of how structure correlates with molecular mobility in the glassy state is inadequate. We used phosphorescence from vanillin dispersed in amorphous films to study the effect of temperature on molecular mobility in the homologous series of oligosaccharides glucose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and maltoheptaose. Phosphorescence emission spectra and intensity decays were collected from −10 to as high as 130 °C. Emission peak energy, a measure of the extent of dipolar relaxation around the excited state prior to emission, decreased monotonically with temperature, decreasing more significantly in the glassy state in larger sugars (higher degree of polymerisation). The intensity decays were well fitted with sums of either four (glucose, maltose, maltotriose) or three exponentials (maltotetraose, maltopentaose, maltohexaose, maltoheptaose); fit lifetimes at each temperature varied over nearly two orders of magnitude, suggesting a comparable range in matrix dynamic heterogeneity. The lifetimes decreased monotonically with temperature, while the lifetime amplitudes favoured the long lifetime components at lower and short lifetime components at higher temperatures near T_g. Arrhenius analysis indicated that the rate of non-radiative decay, which reflects coupling of probe vibrations with matrix motions and thus provides an estimate of the matrix molecular mobility, increased with molecular size in the glassy state. Both apparent activation energy and activation entropy increased systematically with temperature in all sugars. These data provide additional evidence that the rate and extent of molecular mobility in glassy state carbohydrates is higher in sugars of greater molecular size (mass) and thus higher glass transition temperature and provides additional insight into the molecular dynamics of the glassy state in carbohydrates.     

Automated classification of brain tumours from short echo time in vivo MRS data using Gaussian Decomposition and Bayesian Neural Networks

Neuro-oncologists must ultimately rely on their acquired knowledge and accumulated experience to undertake the sensitive task of brain tumour diagnosis. This task strongly depends on indirect, non-invasive measurements, which are the source of valuable data in the form of signals and images. Expert radiologists should benefit from their use as part of an at least partially automated computer-based medical decision support system. This paper focuses on Magnetic Resonance Spectroscopy signal analysis and illustrates a method that combines Gaussian Decomposition, dimensionality reduction by Moving Window with Variance Analysis and classification using adaptively regularized Artificial Neural Networks. The method yields encouraging results in the task of binary classification of human brain tumours, even for tumour types that have seldom been analyzed from this viewpoint.