小兴安岭7种松叶挥发油GC-MS数据的分析

用化学计量学方法分析小兴安岭7种松科植物松叶挥发油气相色谱-质谱(GC-MS)数据,为松叶挥发油的药理活性与其它的应用研究提供依据。(1)用直观推导式演进特征投影(heuristic evolving latent projections,HELP)法分辨重叠色谱峰,得各组分的纯色谱峰和质谱;(2)用正交投影法比较不同挥发油的GC-MS数据;(3)用峰面积归一化法确定各化合物的相对含量;(4)用主要化学成分进行聚类分析。7种松叶挥发油的化学成分为单萜、倍半萜及其衍生物和酯类化合物,按化学成分7种松叶挥发油可分为3类。     

Spoken emotion recognition through optimum-path forest classification using glottal features

A new method for the recognition of spoken emotions is presented based on features of the glottal airflow signal. Its effectiveness is tested on the new optimum path classifier (OPF) as well as on six other previously established classification methods that included the Gaussian mixture model (GMM), support vector machine (SVM), artificial neural networks – multi layer perceptron (ANN-MLP), k-nearest neighbor rule (k-NN), Bayesian classifier (BC) and the C4.5 decision tree. The speech database used in this work was collected in an anechoic environment with ten speakers (5 M and 5 F) each speaking ten sentences in four different emotions: Happy, Angry, Sad, and Neutral. The glottal waveform was extracted from fluent speech via inverse filtering. The investigated features included the glottal symmetry and MFCC vectors of various lengths both for the glottal and the corresponding speech signal. Experimental results indicate that best performance is obtained for the glottal-only features with SVM and OPF generally providing the highest recognition rates, while for GMM or the combination of glottal and speech features performance was relatively inferior. For this text dependent, multi speaker task the top performing classifiers achieved perfect recognition rates for the case of 6th order glottal MFCCs.     

Active time scheduling for rechargeable sensor networks

Recent progress in energy harvesting technologies made it possible to build sensor networks with rechargeable nodes which target an indefinitely long operation. In these networks, the goal of energy management is to allocate the available energy such that the important performance metrics, such as the number of detected threats, are maximized. As the harvested energy is not sufficient for continuous operation, the scheduling of the active and inactive time is one of the main components of energy management. The active time scheduling protocols need to maintain the energy equilibrium of the nodes, while considering the uncertainties of the energy income, which is strongly influenced by the weather, and the energy expenditures, which are dependent on the behavior of the targets. In this paper, we describe and experimentally compare three active time scheduling protocols: (a) static active time, (b) dynamic active time based on a multi-parameter heuristic and (c) utility-based uniform sensing. We show that protocols which take into consideration the probabilistic models of the energy income and expenditure and can dynamically adapt to changes in the environment, can provide a significant performance advantage.     

Phase change materials in the ternary system NH4Cl+CaCl2+H2O

Solubility isotherms of the ternary system (NH₄Cl+CaCl₂+H₂O) were elaborately determined at T= (273.15 and 298.15) K by using the isothermal method. In the equilibrium phase diagram, there are two solubility branches corresponding to the solid phases CaCl₂⋅6H₂O and NH₄Cl. Invariant point compositions are 36.32 wt% CaCl₂ and 3.4 wt% NH₄Cl at 273.15 K, and 45.86 wt% CaCl₂ and 5.22 wt% NH₄Cl at 298.15 K. A Pitzer-Simonson-Clegg thermodynamic model was applied to represent the thermodynamic properties of this ternary system and to construct a partial phase diagram of the ternary system at temperatures between (273.15 and 323.15) K. It was found in the predicted solubility phase diagram that the double salt 2NH₄Cl⋅CaCl₂⋅3H₂O, found by other authors at (323.1 and 348.1) K, will disappear at temperatures below 298.15 K. Besides, it was found that there are two peritectic points in the ternary system with peritectic temperatures at 299.65 K and 298.15 K, and the former peritectic point falls just on the line between the composition points of NH₄Cl and CaCl₂⋅6H₂O. According to phase rule, a solution made of this point will begin to crystallize at 299.65 K and end at 298 K and therefore can be acted as a “pseudo eutectic” phase change material (PCM). A heat storing and releasing experiment of 50 grams of the PCM was carried out, obtaining a satisfying result.     

Multiwalled carbon nanotubes grafted chitosan nanobiocomposite: A prosperous functional nanomaterials for glucose biosensor application

Multiwalled carbon nanotubes (MWNTs) grafted chitosan (CS) nanowire (NW) was prepared by phase separation method. Glucose oxidase (GOx) was sequentially immobilized into MWNT-CS-NW to obtain MWNT-CS-NW/GOx biosensor. Field emission scanning electron microscopy (FESEM) images of MWNT-CS-NW/GOx reveals the existence of MWNT and CS. Cyclic voltammetry and amperometry were used to evaluate the electrochemical determination of glucose. The MWNT-CS-NW/GOx biosensor shows an excellent performance for glucose at +0.34 V with a high sensitivity (5.03 μA/mM) and lower response time (3 s) in a wide concentration range of 1-10 mM (correlation coefficient of 0.9988). In addition, MWNT-CS-NW/GOx biosensor possesses better reproducibility, storage stability and there is negligible interference from other electroactive components.     

A fluorescent chemosensor for cysteine based on naphthalimide derivative in aqueous solution

Naphthalimide derivative (compound 1) containing hydrophilic hexanoic acid group was synthesized and used to recognize cysteine (Cys) in aqueous solution. The fluorescence enhancement of 1 was attributed to the cyclization reaction of 1 with Cys by 1:1 binding stoichiometry, which has been utilized as the basis of fabrication of the Cys-sensitive fluorescent chemosensor. The comparison of this method with some other fluorescence methods for the determination of Cys indicated that the methods can be applied in aqueous solution rather than organic solution. The analytical performance characteristics of the proposed Cys-sensitive chemosensor were investigated. The chemosensor can be applied to the quantification of Cys with a linear range covering from 3.9 × 10⁻⁸ to 1.4 × 10⁻⁵ M and a detection limit of 7.8 × 10⁻⁹ M. And the chemosensor shows excellent selectivity for Cys over other amino acids. Moreover, the response of the chemosensor toward Cys is fast (response time less than 3 min). In addition, the chemosensor has been used for determination of Cys in serum samples with satisfactory results.     

Amperometric biosensor for catechol using electrochemical template process

A novel amperometric biosensor for the determination of catechol was developed accordingly to the electrochemical template procedure. The optimum fabricating conditions of the biosensor were studied. The resulting biosensor with the limit of less than 0.05 μM can be used for detection of catechol in the linear range of 2.5-140 μM. The maximum response current (I_max) and the Michaelis-Menten constant (k′_m) are 3.08 μA and 77.52 μM, respectively. The activation energy (E_a) of the polyphenol oxidase (PPO) catalytic reaction is 25.56 kJ mol⁻¹ in the B-R buffer. The stability of the PANI-CA biosensor fabricated with the electrochemical template process (retains 86% of the original activity after four months) is much higher than that fabricated with one-step and two-step processes (retains 75% of the original activity after four months). The effects of potential and pH on the response current of the biosensor are also described.     

Electrochemical studies of bovine serum albumin immobilization onto the poly-o-phenylenediamine and carbon-coated nickel composite film and its interaction with papaverine

A biosensor based on bovine serum albumin (BSA) and poly-o-phenylenediamine (PoPD)/carbon-coated nickel (C-Ni) nanobiocomposite film modified electrode has been developed to study the interaction of BSA with papaverine (PAP). The well-dispersed C-Ni nanoparticles were dripped onto the glassy carbon electrode (GCE) surface firstly, and PoPD films were subsequently electropolymerized by cyclic voltammetry (CV) to prepare PoPD/C-Ni/GCE. Finally, the BSA was easily immobilized on the PoPD films via electrostatic adsorption. The morphology and the electrochemical properties of the fabricated composite electrodes were examined by scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS), respectively. The interaction of PAP with BSA was monitored by differential pulse voltammetry (DPV), using PoPD as the electrochemical indicator. The binding constant (K), obtained by DPV, was 1.7 × 10⁴ L/mol, which was consistent with the fluorescence analysis. This constructed biosensor also exhibited a fine linear correlation with PAP concentration range of 2.5 × 10⁻⁹-4.5 × 10⁻⁵ mol/L and a detection limit of 8.3 × 10⁻¹⁰ mol/L was achieved by DPV.     

Characterisation and control of bubbling behaviour in gas–solid fluidised beds

Bubbling fluidised beds are often exploited for the good mixing of phases they promote, which is required in many chemical processes. However, the bubbles cause heterogeneity in the fluidised system, and their dynamics must be understood for good process control. In this paper, the dynamic behaviour of the bubbles in a planar gas–solid fluidised bed is described analytically and experimentally validated. The bed resembles a temporary buffer of gas for which the bubble residence time in the bed is important. Subsequently, a closed-loop controller was developed using visual feedback to regulate the process.     

Exploring the potential of boron-doped nanographene as efficient charge transport and nonlinear optical material: A first-principles study

Owing to their excellent electrochemical properties, graphenes found applications in several fields ranging from semiconductors, solar cells, field effect transistors, and nanoscale electronic devices as well as in nonlinear optical (NLO) applications. The structural features, electro-optical, charge transport and nonlinear optical properties of the boron-doped graphene (BG) compound 1 were studied using density functional theory methods The BG compound comprises a central electron deficient site of boron atoms, which can serve as electron acceptor while terminal alkoxy groups as donors leading to powerful donor-π-acceptor (D-π-A) configuration. The experimental crystal structure was successfully reproduced by optimized ground state geometry at PBE0/6-311G* level of theory for isolated molecule. The experimental lattice parameters, geometries, crystal presentation and alignment of molecules in the unit cells as well as their packing orientation of BG compound 1 was also efficiently reproduced by applying periodic boundary conditions (PBC) at PBE level. The comprehensive intramolecular charge transfer (CT) was realized from terminal rings of the HOMO to the electron deficient sites of boron atoms of the LUMO. The nature of BG compound 1 might be more towards hole transport even though its hole reorganization energy is twice than that of the electron one due to the significant higher hole transfer integral values. The superior hole transfer integrals and intrinsic mobility values of the BG compound 1 might lead remarkable hole transport contender as compared to many other organic materials. The narrow band gap, density of states profile, dielectric function, uniform conductivity functions and noteworthy electronic as well as CT properties revealed that the BG compound 1 might be proficient optoelectronic contestant having intermolecular CT as well as intramolecular CT with optimal stability. A comparison of static third-order polarizability <γ> of BG compound 1, as calculated in present investigation, was also performed with some standard NLO molecules as well as graphene nanoflakes. Moreover, longitudinal component γ_zzzz of parent compound has been found 12 and 4 times larger than those of previously reported open-shell poly aromatic hydrocarbons (PAH). Interestingly, by increasing the donor ability, i.e., introduction of C₂H₂PhNH₂ groups in place of OC₄H₉ groups (BG compound 3) at terminal positions boosts the <γ> amplitude ∼ 8 times than that of its parent BG compound 1.