Chromatographic Behavior of Food Additives on Thin Layers of Titanium(IV) Silicate Ion-Exchanger

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of acetaldehyde, o-anisidine, ascorbic acid, benzoic acid, butylated hydroxyanisole, butylated...     

An integrated fuzzy DEA–Fuzzy simulation approach for optimization of operator allocation with learning effects in multi products CMS

This paper presents an integrated fuzzy data envelopment analysis (FDEA) and fuzzy computer simulation approach for optimization of operator allocation in multi product cellular manufacturing systems (CMS) with learning effects. Operator allocation with learning effects is a challenging issue in flexible manufacturing systems in general and in CMS in particular. The main contribution of this work is taking into consideration various operators layouts and learning effects using fuzzy simulation and fuzzy DEA. FDEA is utilized to assess simulation alternatives in various levels of uncertainty. Previous studies consider only one type of product with crisp inputs, whereas this study considers multi-products and fuzzy set up times and processing times for CMS modeling. In addition, this study considers and integrates learning effects for optimum operators’ allocation. Moreover, more robust CMS assessment indicators are used in the proposed model. A case study illustrates the practicability, effectiveness and superiority of the proposed methodology.     

The Leading-Order Charm Quark Contribution to the Next-to-Leading-Order Proton Structure Function Using {\cal A}=3 Mirror Nuclei as Input Valence Quarks

The charm quark contribution to the proton structure function (SF) is investigated in the leading-order (LO) QCD at small x region. A next-to-leading order (NLO) QCD analysis for the proton SF is made within the renormalization scheme of the radiation parton evolution model (DGLAP). The valence quark distribution is obtained from the relativistic quark-exchange calculation for the mirror nuclei, i.e., ³He and ³H, which is based on a realistic model. The inverse Mellin technique is performed to extract the parton distribution in the (x, Q ²)-plane. The calculated F ₂ ^c (x, Q ²) and F ₂ ^p (x, Q ²) as well as the longitudinal SF, F _L ^p (x, Q ²) are compared with the experimental data available at present, namely H1, ZEUS, and HERMES at HERA ring as well as other theoretical models, especially the hard pomeron phenomenological model.     

Cause of sudden magnetic reconnection in a laboratory plasma

The cause for sudden reconnection in reversed field pinch plasmas is determined experimentally for two cases: large reconnection events (the sawtooth crash) and small reconnection events during improved confinement. We measure the term in the MHD equations which represents the driving (or damping) of edge tearing modes due to the axisymmetric magnetic field. The term is negative for large reconnection events (the modes are stable, implying that reconnection may be driven by nonlinear coupling to other modes) and positive for small reconnection events (modes are unstable, reconnection is spontaneous).     

NMR study,theoretical calculations for assignment of the Z‐ and E‐isomers,and kinetics investigation of stable phosphorus ylides involving a 2‐mercapto‐4,6‐dimethyl pyrimidine

In the present work, NMR, theoretical, kinetics, and mechanism investigations were undertaken for a one‐pot condensation reaction between 2‐mercapto‐4,6‐dimethyl pyrimidine and dialkyl acetylenedicarboxylates in the presence of triphenyphosphine containing novel stable phosphorus ylides 4a–c . Herein, theoretical calculations have been employed for assignment of the most stable isomers (Z or E) of phosphorus ylides 4a,c by natural population analysis, atoms in molecules methods, and CHelpG keyword, in which E‐ 4(a, c) are more stable forms as the majors. The ¹H, ¹³C, and ³¹P NMR data of these ylides are consistent with results obtained from theoretical calculations. In addition, kinetic investigation of new ylides was undertaken by ultraviolet spectrophotometry. Useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates), and also the concentration of reactants on the rate of reactions. The proposed mechanism was confirmed according to the obtained results and a steady‐state approximation, and the first step (k₂) of the reaction was recognized as a rate‐determining step on the basis of the experimental data. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:462–474, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20632     

Study of reaction between activated acetylenes and N,N′‐diethyl‐2‐thiobarbituric acid in the presence of isocyanides or triphenylphosphine

In a series of separate experiments reaction between N,N′‐diethyl‐2‐thiobarbituric acid and acetylenic diesters in the presence of isocyanides or triphenylphosphine led to highly functionalized 4H‐pyrano[2,3‐d]thiopyrimidine or 1,4‐di‐ionic organophosphorus derivatives. The ¹H NMR spectra of diethyl‐7‐(2,6‐dimethylphenylamino)‐4‐oxo‐2‐thio‐ 1,3‐diethyl‐4H‐pyrano[2,3‐d]pyrimidine‐5,6‐dicarboxylate showed dynamic NMR effect that was attributed to restricted rotation around the aryl‐nitrogen single bond. Activation free energy (ΔG^≠) for this process is about 54.85 ± 2 kJ mol⁻¹. Betaines as 1,4‐diionic organophosphorus compounds in this reaction are possessed of two vicinal stereogenic centers and exist in the solution as a mixture of two diastereoisomers. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:228–235, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20601     

Magnetic Branes in Brans-Dicke-Maxwell Theory

We present a new class of magnetic brane solutions in (n+1)-dimensional Brans-Dicke-Maxwell theory in the presence of a quadratic potential for the scalar field. These solutions are neither asymptotically flat nor (anti)-de Sitter. Our strategy for constructing these solutions is applying a conformal transformation to the corresponding solutions in dilaton gravity. This class of solutions represents a spacetime with a longitudinal magnetic field generated by a static brane. They have no curvature singularity and no horizons but have a conic geometry with a deficit angle δ. We generalize this class of solutions to the case of spinning magnetic brane with all rotation parameters. We also use the counterterm method and calculate the conserved quantities of the solutions.     

Modeling the influence of social networks and environment on energy balance and obesity

The influence of social networks on the development of obesity has been demonstrated, and several models have been proposed. However, these models are limited since they consider obesity as a ‘contagious’ phenomenon that can be caught if most social contacts are deemed obese. Furthermore, social networks were proposed as a means to mitigate the obesity epidemic, but the interaction of social networks with environmental factors could not yet be explored as it was not accounted for in the current models. We propose a new model of obesity to face these limitations. In our model, individuals influence each other with respect to food intake and physical activity, which may lead to changes depending on the environment, and will impact energy balance and weight. We illustrate the potential of our model via two questions: could we focus on social networks and neglect environmental sources of influence, at least from a modelling viewpoint? Are some social structures less prone to be influenced by their environment? We performed a factorial analysis based on both synthetic and real-world social networks, and found that the environment was a key component behind changes in weight but its contribution was mitigated by structural properties of the population. Furthermore, the contribution of the environment was not dictated by macro-level properties (small-world and scale-free), which suggests that particular patterns of social ties at the micro-level are involved in making populations more resilient to change and less influenced by the environment.     

The first report of [2+2] ketene–imine cycloaddition reactions (Staudinger) on carbon nanotubes

Several new carbon nanotube-functionalized β-lactams have been synthesized from chiral imines derived from β-d-glucopyranosylamine and a ketene from carbon nanotube-based oxyacetic acid via a [2+2] cycloaddition reaction. The cycloadducts were characterized by thermogravimetric analysis, Raman spectrometry, IR, and N₂ adsorption processes.     

Can Inflation, Dark Matter and Dark Energy Be Described in Terms of a Single, Real Scalar Field?

In this article, our aim is to consider inflation, dark energy and dark matter in the framework of a real scalar field. To this end, we use the quintessence approach. We have tried a real scalar field with a specific self-interaction potential in a spacially flat universe. Numerical results indicate that this potential can drive the expansion of the universe in three distinct phases. The first phase behaves as an inflationary expansion. For this stage, setting the scalar field’s initial value to ϕ ₀≥1.94 leads to N 3 68\mathcal{N}\geq 68 favored by observation. After the inflationary phase, the scalar field starts an oscillatory behavior which averages to a =0\bar{w}=0 fluid. This stage can be taken as a cold dark matter (p≈0) epoch expected from works on the structure formation issue. Observations and cosmological models indicate that t _inf ≈10⁻³⁵ s and the matter dominated lasts for t _m ≈10¹⁷ s, hence (\fract_mt_inf)_obs ? 10⁵²(\frac{t_{m}}{t_{inf}})_{obs}\approx10^{52}. We have shown that the present model can satisfy such a constraint. Finally, the scalar field leaves the oscillatory behavior and once again enters a second inflationary stage which can be identified with the recent accelerated expansion of the universe. We have also compared our model with the ΛCDM model and have found a very good agreement between the equation of state parameter of both of models during the DM and DE era.