Isolation and identification of a ferulic acid dehydrotrimer from saponified maize bran insoluble fiber

Following saponification of maize bran insoluble fiber a ferulic acid dehydrotrimer was isolated using Sephadex LH-20 chromatography. Structural identification was carried out using UV-spectroscopy, mass spectrometry and 1D and 2D NMR experiments ( ¹H, ¹³C, DEPT, COSY, TOCSY, ¹³C- ¹H HSQC, HMBC). UV-spectroscopy indicated characteristics of ferulate structures, mass spectrometry showed a trimeric ferulate structure, and the NMR spectra provided diagnostic evidence for its being a 5-5/8-O-4-coupled dehydrotrimer. Ferulic acid dehydrodimers are mainly derived from diferulates which cross-link polysaccharides. Because of the involvement of a 5-5-dehydrodiferulic acid unit in the identified trimer, this novel dehydrotriferulic acid from cereal grain fiber need not imply the cross-linking of three polysaccharide chains; molecular modeling of the ferulate dehydrodimerization in earlier studies showed that the 5-5-diferulate, uniquely, can form intramolecularly. This first identified ferulic acid dehydrotrimer nevertheless reveals that polysaccharide chains can be more extensively cross-linked than previously recognized.     

Prediction of parking space availability in real time

Intelligent parking reservation (IPR) systems allow customers to select a parking facility according to their preferences, rapidly park their vehicle without searching for a free stall, and pay their reservation in advance avoiding queues. Some IPR systems interact with in-vehicle navigation systems and provide users with information in real time such as capacity, parking fee, and current parking utilization. However, few of these systems provide information on the forecast utilization at specific hours - a process that requires the study of the competition between parking alternatives for the market share. This paper proposes a methodology for predicting real-time parking space availability in IPR architectures. This methodology consists of three subroutines to allocate simulated parking requests, estimate future departures, and forecast parking availability. Parking requests are allocated iteratively using an aggregated approach as a function of simulated drivers’ preferences, and parking availability. This approach is based on a calibrated discrete choice model for selecting parking alternatives. A numerical comparison between a one-by-one simulation-based forecast and the proposed aggregated approach indicates that no significant discrepancies exists, validating and suggesting the use of the less time consuming proposed aggregated methodology. Results obtained from contrasting predictions with real data yielded small average error availabilities. The forecast improves as the system registers arrivals and departures. Thus, the forecast is adequate for potential distribution in real-time using different media such as Internet, navigation systems, cell phones or GIS.     

Playing Mastermind with Constant-Size Memory

We analyze the classic board game of Mastermind with n holes and a constant number of colors. The classic result of Chvátal (Combinatorica 3:325–329, 1983) states that the codebreaker can find the secret code with Θ(n/logn) questions. We show that this bound remains valid if the codebreaker may only store a constant number of guesses and answers. In addition to an intrinsic interest in this question, our result also disproves a conjecture of Droste, Jansen, and Wegener (Theory Comput. Syst. 39:525–544, 2006) on the memory-restricted black-box complexity of the OneMax function class.     

Convergence of a lowest-order finite element method for the transmission eigenvalue problem

The transmission eigenvalue problem arises in scattering theory. The main difficulty in its analysis is the fact that, depending on the chosen formulation, it leads either to a quadratic eigenvalue problem or to a non-classical mixed problem. In this paper we prove the convergence of a mixed finite element approximation. This approach, which is close to the Ciarlet–Raviart discretization of biharmonic problems, is based on Lagrange finite elements and is one of the less expensive methods in terms of the amount of degrees of freedom. The convergence analysis is based on classical abstract spectral approximation result and the theory of mixed finite element methods for solving the stream function–vorticity formulation of the Stokes problem. Numerical experiments are reported in order to assess the efficiency of the method.     

Matching Polyhedral Terrains Using Overlays of Envelopes

For a collection $\F$ of $d$-variate piecewise linear functions of overall combinatorial complexity $n$, the lower envelope $\E(\F)$ of $\F$ is the pointwise minimum of these functions. The minimization diagram $\M(\F)$ is the subdivision of $\reals^d$ obtained by vertically (i.e., in direction $x_{d+1}$) projecting $\E(\F)$. The overlay $\O(\F,\G)$ of two such subdivisions $\M(\F)$ and $\M(\G)$ is their superposition. We extend and improve the analysis of de Berg et al. \cite{bgh-vdt3s-96} by showing that the combinatorial complexity of $\O(\F,\G)$ is $\Omega(n^d \alpha^{2}(n))$ and $O(n^{d+\eps})$ for any $\eps>0$ when $d \ge 2$, and $O(n^2 \alpha(n) \log n)$ when $d=2$. We also describe an algorithm that constructs $\O(\F,\G)$ in this time. We apply these results to obtain efficient general solutions to the problem of matching two polyhedral terrains in higher dimensions under translation. That is, given two piecewise linear terrains of combinatorial complexity $n$ in $\reals^{d+1}$, we wish to find a translation of the first terrain that minimizes its distance to the second, according to some distance measure. For the perpendicular distance measure, which we adopt from functional analysis since it is natural for measuring the similarity of terrains, we present a matching algorithm that runs in time $O(n^{2d+\eps})$ for any $\eps>0$. Sharper running time bounds are shown for $d \le 2$. For the directed and undirected \Hd\ distance measures, we present a matching algorithm that runs in time $O(n^{d^2+d+\eps})$ for any $\eps>0$.     

Investigation of PECVD dielectrics for nondispersivemetal-insulator-metal capacitors

Metal-insulator-metal (MIM) capacitors with PECVD nitride exhibit trap-induced dispersive behavior, which leads to degradation in capacitor linearity at low frequencies, limiting the accuracy in precision analog circuits. While LPCVD oxide results in nondispersive behavior, the high deposition temperature excludes the use of LPCVD dielectrics for MIM capacitors using the standard back-end metal layers as capacitor bottom plates. The latter is preferred in view of the low substrate coupling needed for RF applications. In this work, alternative PECVD dielectrics have been investigated with respect to frequency dependence of voltage linearity, hysteresis, matching, and leakage characteristics. It will be shown that ONO stacks offer a combination of good voltage linearity, absence of dispersive behavior and hysteresis, excellent matching, and low leakage     

Experimental performances of a LiBr-water absorption facility equipped with adiabatic absorber

A facility for experimental evaluation of innovative components forming part of a single effect LiBr-H₂O adiabatic absorption chiller is described. Plate heat exchangers have been incorporated in the design. Two adiabatic absorber configurations, droplets and liquid sheets, were designed and tested and its performances parameters were experimentally determined. Evaporator limitations have been identified and included in the analysis. Liquid accumulation leads to overflow of refrigerant out of the evaporators. Some general observations, regarding particular operating conditions, are reported. The absorber performance has been characterized in terms of heat and mass transfer through the heat conductance and the effectiveness. The influence of the recirculation ratio is presented for both cases. The liquid sheet configuration has shown better evaluation parameters than droplets configuration. A significant reduction in the absorber size (up to 50%) as compared to using droplets is possible.