Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Gas chromatography-mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to assign the components from GC x GC-TOF-MS analysis. The distributions of aliphatic hydrocarbons and aromatics were also investigated. Over 100 isoprenoid hydrocarbons were detected, including carotene degradation products, phytadiene isomers and carbocyclic diterpenoids. A total of 1800 hydrocarbons were tentatively identified, including aliphatic hydrocarbons, aromatics, and isoprenoid hydrocarbons. The identified hydrocarbons by GC x GC-TOF-MS were far more than those by GC-MS. (C) 2004 Elsevier B.V. All rights reserved.

Low-temperature heat capacities and derived thermodynamic functions of cyclohexane

The low-temperature heat capacities of cyclohexane were measured in the temperature range from 78 to 350 K by means of an automatic adiabatic calorimeter equipped with a new sample container adapted to measure heat capacities of liquids. The sample container was described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on water. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.3%, while the inaccuracy is within +/-0.4%, compared with the reference data in the whole experimental temperature range. Two kinds of phase transitions were found at 186.065 and 279.684 K corresponding solid-solid and solid-liquid phase transitions, respectively. The entropy and enthalpy of the phase transition, as well as the thermodynamic functions {H-(T)- H-298.15 K} and {S-(T)-S-298.15 K}, were derived from the heat capacity data. The mass fraction purity of cyclohexane sample used in the present calorimetric study was determined to be 99.9965% by fraction melting approach.

Heat capacities and thermodynamic functions of p-chlorobenzoic acid

The heat capacities of p-chlorobenzoic acid were measured in the temperature range from 80 to 580 K by means of an automatic adiabatic calorimeter equipped with a small sample cell of internal volume of 7.4cm(3). The construction and procedures of the calorimetric system were described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on alpha-Al2O3. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.28 per cent, while the inaccuracy is within +/-0.40 per cent, compared with the recommended reference data in the whole experimental temperature range. A fusion transition at T = 512.280 K was found from the C-p-T curve of p-chlorobenzoic acid. The enthalpy and entropy of the phase transition, as well as the thermodynamic functions {G((T)) - G((298.15))}, {H-(T) - H-(298.15)} and {S-(T) - S-298.15}, were derived from the heat capacity data. The mass fraction purity of p-chlorobenzoic acid sample used in the present calorimetric study was determined to be 0.99935 by fraction melting approach. (C) 2002 Elsevier Science Ltd. All rights reserved.

Profiling of Complex Microbial Populations by Denaturing Gradient Gel Electrophoresis Analysis of Polymerase Chain Reaction-Amplified Genes Coding for 16S rRNA

We describe a new molecular approach to analyzing the genetic diversity of complex microbial populations. This technique is based on the separation of polymerase chain reaction-amplified fragments of genes coding for 16S rRNA, all the same length, by denaturing gradient gel electrophoresis (DGGE). DGGE analysis of different microbial communities demonstrated the presence of up to 10 distinguishable bands in the separation pattern, which were most likely derived from as many different species constituting these populations, and thereby generated a DGGE profile of the populations. We showed that it is possible to identify constituents which represent only 1% of the total population. With an oligonucleotide probe specific for the V3 region of 16S rRNA of sulfate-reducing bacteria, particular DNA fragments from some of the microbial populations could be identified by hybridization analysis. Analysis of the genomic DNA from a bacterial biofilm grown under aerobic conditions suggests that sulfate-reducing bacteria, despite their anaerobicity, were present in this environment. The results we obtained demonstrate that this technique will contribute to our understanding of the genetic diversity of uncharacterized microbial populations.

Properties of complex of Tb(III) and poly(N-isopropylacrylamide)-g-poly(N-isopropylacrylamide-co-styrene) core-shell nanoparticles

We successfully prepared a new kind of thermoresponsive and fluorescent complex of Tb(III) and PNIPAM-g-P(NIPAM-co-St) (PNNS) core-shell nanoparticle. It was found that Tb(III) mainly bonded to 0 of the carbonyl groups of PNNS, forming the novel (PNIPAM-g-P(NIPAM-co-St))-Tb(III) (PNNS-Tb(III)) complex. The maximum emission intensity of the complex at 545 nm is enhanced about 223 times comparing to that of the pure Tb(III). The intramolecular energy transfer efficiency from PNNS to Tb(III) reaches 50%. When the weight ratio of Tb(III) and the PNNS-Tb(III) complex is 1.2 wt.%, the enhancement of the emission fluorescence intensity at 545 nm is highest.

Solvothermal synthesis of complex fluorides KCoF3 and KNiF3

Complex fluorides KCoF3 and KNiF3 with perovskite structures were solvothermally synthesized at 120-180 C and characterized by means of X-ray powder diffraction, scanning electron microscopy. thermogravimetric analysis and infrared spectroscopy.

The mild hydrothermal synthesis of complex fluorides of AZnF(3) (A = Na, K)

The complex fluorides of AZnF(3) (A = Na, K), which are isostructural with perovskite phases were obtained by the method of hydrothermal synthesis at 160-220 degrees C. Compared with traditional high-temperature solid-state method, the products were pure and contained lower amount of oxygen.

Chemical bond analysis of the correlation between crystal structure and nonlinear optical properties of complex crystals

Second order nonlinear optical (NLO) properties of single crystals with complex structures are studied, from the chemical bond viewpoint. Contributions of each type of constituent chemical bond to the total linearity and nonlinearity are calculated from the actual crystal structure, using the chemical bond theory of complex crystals and the modified bond charge model. We have quantitatively proposed certain relationships between the crystal structure and its NLO properties. Several relations have been established from the calculation. Our method makes it possible for us to identify, predict and modify new NLO materials according to our needs. (C) 1999 Elsevier Science B.V. All rights reserved.

Hydrothermal synthesis and lanthanide doping of complex fluorides, LiYF4, KYF4 and BaBeF4 under mild conditions

The complex fluorides LiYF4, KYF4, BaBeF4 and AYF(4)Eu(x) (A = Li, K) are hydrothermally synthesized at 140-240 degrees C and characterized by powder X-ray diffraction, thermogravimetric analysis, IR spectroscopy, scanning electron microscopy and luminescence measurements.

Forms and functions of inorganic carbon in the Jiaozhou Bay sediments

Inorganic carbon forms and their influencing factors, mutual transformation and contribution to carbon cycling in the Jiaozhou Bay sediments were discussed. The results show that inorganic carbon in sediments could be divided into five forms: NaCl form, NH3 center dot H2O form, NaOH form, NH2OH center dot HCl form and HCl form. Thereinto, NH2OH center dot HCl form and HCl form account for more than 70% of total inorganic carbon. There was close relationship among every form of inorganic carbon and their correlativity was clearly different with different sedimentary environment except the similar strong positive correlation among NH2OH center dot HCl form, HCl form and total inorganic carbon in all regions of the Jiaozhou Bay. All forms of inorganic carbon were influenced by organic carbon, pH, Eh, Es, nitrogen and phosphorus in sediments, but their influence had different characteristics in different regions. Every farm of inorganic carbon transformed into each other continuously during early diagenesis of sediments and the common phenomenon was that NaCl form, NH3 center dot H2O form, NaOH form and NH2OH center dot HCl form might transform into steady HCl form. NaCl form, NH3 center dot H2O form, NaOH form and NH2OH center dot HCl form could participate in carbon recycle and they are potential carbon source; HCl form may be buried for a long time in sediments, and it may be one of the final resting places of atmospheric CO2. Inorganic carbon which entered into sediments was about 4.98 x 10(10) g in the Jiaozhou Bay every year, in which about 1.47x10(10) g of inorganic carbon might be buried for a long time and about 3.51. x 10(10) g of inorganic carbon might return into seawater and take part in carbon recycling.

A Theory of Networks for Appxoimation and Learning

Learning an input-output mapping from a set of examples, of the type that many neural networks have been constructed to perform, can be regarded as synthesizing an approximation of a multi-dimensional function, that is solving the problem of hypersurface reconstruction. From this point of view, this form of learning is closely related to classical approximation techniques, such as generalized splines and regularization theory. This paper considers the problems of an exact representation and, in more detail, of the approximation of linear and nolinear mappings in terms of simpler functions of fewer variables. Kolmogorov's theorem concerning the representation of functions of several variables in terms of functions of one variable turns out to be almost irrelevant in the context of networks for learning. We develop a theoretical framework for approximation based on regularization techniques that leads to a class of three-layer networks that we call Generalized Radial Basis Functions (GRBF), since they are mathematically related to the well-known Radial Basis Functions, mainly used for strict interpolation tasks. GRBF networks are not only equivalent to generalized splines, but are also closely related to pattern recognition methods such as Parzen windows and potential functions and to several neural network algorithms, such as Kanerva's associative memory, backpropagation and Kohonen's topology preserving map. They also have an interesting interpretation in terms of prototypes that are synthesized and optimally combined during the learning stage. The paper introduces several extensions and applications of the technique and discusses intriguing analogies with neurobiological data.

Typed Abstraction of Complex Network Compositions

The heterogeneity and open nature of network systems make analysis of compositions of components quite challenging, making the design and implementation of robust network services largely inaccessible to the average programmer. We propose the development of a novel type system and practical type spaces which reflect simplified representations of the results and conclusions which can be derived from complex compositional theories in more accessible ways, essentially allowing the system architect or programmer to be exposed only to the inputs and output of compositional analysis without having to be familiar with the ins and outs of its internals. Toward this end we present the TRAFFIC (Typed Representation and Analysis of Flows For Interoperability Checks) framework, a simple flow-composition and typing language with corresponding type system. We then discuss and demonstrate the expressive power of a type space for TRAFFIC derived from the network calculus, allowing us to reason about and infer such properties as data arrival, transit, and loss rates in large composite network applications.