Corn stover fractions and bioenergy

Information is presented on structure, composition, and response to enzymes of corn stover related to barriers for bioconversion to ethanol. Aromatic compounds occurred in most tissue cell walls. Ferulic acid esterase treatment before cellulase treatment significantly improved dry weight loss and release of phenolic acids and sugars in most fractions over cellulase alone. Leaf fractions were considerably higher in dry weight loss and released sugars with esterase treatment, but stem pith cells gave up the most phenolic acids. Results help identify plant fractions more appropriate for coproducts and bioconversion and those more suitable as residues for soil erosion control.     

640 × 512 pixel narrow-band, four-band, and broad-band quantum well infrared photodetector focal plane arrays

A 9 μm cutoff 640 × 512 pixel hand-held quantum well infrared photodetector (QWIP) camera has been demonstrated with excellent imagery. A noise equivalent differential temperature (NEDT) of 10.6 mK is expected at a 65 K operating temperature with f/2 optics at a 300 K background. This focal plane array has shown background limited performance at a 72 K operating temperature with the same optics and background conditions. In this paper, we discuss the development of this very sensitive long-wavelength infrared camera based on a GaAs/AlGaAs QWIP focal plane array and its performance in quantum efficiency, NEDT, uniformity, and operability. In the second section of this paper, we discuss the first demonstration of a monolithic spatially separated four-band 640 × 512 pixel QWIP focal plane array and its performance. The four spectral bands cover 4–5.5, 8.5–10, 10–12, and 13.5–15 μm spectral regions with 640 × 128 pixels in each band. In the last section, we discuss the array performance of a 640 × 512 pixel broad-band (10–16 μm full-width at half-maximum) QWIP focal plane.     

Application of a Near-Optimal Reinforcement Learning Controller to a Robotics Problem in Manufacturing: A Hybrid Approach

Optimization theory provides a framework for determining the best decisions or actions with respect to some mathematical model of a process. This paper focuses on learning to act in a near-optimal manner through reinforcement learning for problems that either have no model or the model is too complex. One approach to solving this class of problems is via approximate dynamic programming. The application of these methods are established primarily for the case of discrete state and action spaces. In this paper we develop efficient methods of learning which act in complex systems with continuous state and action spaces. Monte-Carlo approaches are employed to estimate function values in an iterative, incremental procedure. Derivative-free line search methods are used to obtain a near-optimal action in the continuous action space for a discrete subset of the state space. This near-optimal control policy is then extended to the entire continuous state space via a fuzzy additive model. To compensate for approximation errors, a modified procedure for perturbing the generated control policy is developed. Convergence results under moderate assumptions and stopping criteria are established.     

Calculation of the asymmetry parameters of the angular distribution and of the spin polarization of Auger electrons for open-shell atoms

By means of the multichannel Hartree-Fock-Dirac method, the parameters β and α₂ of the angular distribution of Auger electrons and the parameter β₂ of their spin polarization are calculated for sodium, krypton, xenon, barium, mercury, and excited argon. Relevant Coulomb matrix elements are determined by using orthogonal multielectron initial-and final-state wave functions for intermediate-type coupling in a relativistic approximation. Exchange interaction is taken into account in all calculations. A comparison of the results of calculations performed in the frozen-core approximation and those obtained with orthogonal initial-and final-state wave functions reveals that the relaxation of core orbital processes has only a slight effect on the anisotropy parameters of the angular distribution. The resulting values of the parameters β, α₂, and β₂ are compared with the results of different calculations.     

Recent trends and open issues in reverse engineering

This paper discusses recent trends in the field of reverse engineering, particularly those highlighted at the Second Working Conference on Reverse Engineering, held in July 1995. The trends observed include increased orientation toward tasks, grounding in complex real-world applications, guidance from empirical study, analysis of non-code sources, and increased formalization. The paper also summarizes open research issues and provides pointers to future events and sources of information in this area.     

Electronic interactions in aromatic an heteroaromatic two-ring systems

The chemical shifts of the methyl protons ( ) in the PMR spectra and the integral intensities (A^1/2) of the band of the symmetrical CH stretching vibration of the methyl group in the IR spectra were measured for an extensive series of methyl derivatives of aromatic and heteroaromatic compounds including 3-, 4-, 5-, and 6-substituted 1- and 2-methylnaphthalenes, 4-, 5-, 6-, and 7-substituted 2-methylquinolines, and 5- and 6-substituted 2-methylbenzothiazoles, as well as a number of two- and three-ring systems that do not contain substituents. The changes in the chemical shifts are interpreted with allowance for two principal contributions: the contribution from the ring currents and the contribution from the changes in the electron densities (q) on the H and C atoms of the methyl group. The fact of the existence of a linear relationship between the corrected (for the ring current) values and the calculated (by the CNDO/2 method) electron charges q_C and q_H (the latter plays the dominant role) indicates that the electronic effects of the substituent make the principal contribution to the changes in the shielding constants of the protons of the methyl group in most of the investigated compounds. Similarly, the charges on the H and C atoms of the methyl group convey the trend of the integral intensities of the IR bands, thereby confirming the primarily electronic nature of the effects of structural factors on the A^1/2 values.See [2] for communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 390–396, March, 1979.     

Conversion of Allylic Alcohols into Allylic Nitromethyl Compounds via a Palladium-Catalyzed Solvolysis: An Enantioselective Synthesis of an Advanced Carbocyclic Nucleoside Precursor(1)

A two-step reaction sequence to homoallylic nitro compounds from allylic alcohols is presented. Ethoxy carbonylation of the alcohols with ethyl chloroformate provides the corresponding allylic ethyl carbonates in high yields. Exposure of these substrates to catalytic palladium(0) in CH(3)NO(2) initiates a reaction sequence, ionization-decarboxylation-nitromethylation, that culminates with the formation of nitroalkenes. The regio- and stereochemical outcomes of the nitromethyl allylation reaction can be explained by the behavior of the transient pi-allylpalladium complexes. This methodology serves as a centerpiece for the synthesis of an important carbocyclic nucleoside intermediate.     

Synthesis and Characterization of Fluoro- and Chloro- bimetallic Alkoxides as Precursors for Luminescent Metal Oxide Materials via Sol-Gel Technique

Heterobimetallic alkoxides are broadly recognized as versatile precursors for luminescence materials, and efforts are being made to develop novel routes by applying the concept of geometrical molecular design, for their synthesis and to design a single source precursor suited to photoluminescent materials. Novel and new series of bimetallic alkoxides has been prepared by metathesis route. They exhibit a lower sensitivity towards hydrolysis and so they are easier to handle as compared to other alkoxides. All the compounds were characterized by elemental analysis, FT-IR and multinuclear NMR spectroscopies. FT-IR revealed that the molecular structure of these metal alkoxides was retained to a large extent in 4 ： 1 halogenated alcohol-benzene solution. The heteronuclear NMR spectroscopy provided useful information about chemical shifts for better understanding the likely structure based on interactions with their coordinate metals. The mass spectra show similar types of fragmentation pattern. SEM-EDS analyses showed consistency with the formulation. XRD patterns show an enhanced homogeneity at high temperature. TGA measurements show that thermal decomposition occured in steps that depended entirely on the chemical compositions and the synthesis routes. SEM observation reveals that the morphology and particle size strongly depend on synthesis routes for their precursors.