Increase in energy and land use by a bio-based chemical industry

About 80% of the chemical products are still based on crude oil. Bio-based materials will increasingly gain importance. As the fraction of oxygen is normally higher in biomass than in crude oil as well as in the derived conventional products, this implies a need to develop new synthesis pathways. Depending on the types of new synthesis pathways, the effects of a complete raw-material change on land and exergy use differ. Here, different synthesis pathways starting from glucose and plant oil to different kinds of end products are evaluated utilizing material and exergy balances. These evaluations are carried out under today's and future conditions and constraints, like yield, demand of organic chemicals and world population. The analysis in this paper shows that the land and energy use can be significantly reduced, if the products are adapted to the chemical structure of their bio-based feedstock.     

Formation Mechanism of Alkyl Nitrites,Valuable Intermediates in C1-Upgrading Chemistry and Oxidation Processes

In this contribution we use computational tools to investigate the reaction of alcohol substrates with reactive nitrogen oxide species such as N₂O₃ and N₂O₄, leading to the formation of alkyl nitrites. These nitrites are interesting intermediates which can be processed to various valuable chemicals such as ketones/aldehydes and dimethyl oxalate while regenerating NO _x . As such, NO _x is used as an oxidation mediator, converting alcohol substrates to more reactive nitrites which can be selectively converted to more desired compounds, closing a catalytic cycle in NO _x species.     

Metamer density estimated color correction

Color correction is the transformation of response values of scanners or digital cameras into a device- independent color space. In general, the transformation is not unique due to different acquisition and viewing illuminants and non-satisfaction of the Luther–Ives condition by a majority of devices. In this paper we propose a method that approximates the optimal color correction in the sense of a minimal mean error. The method is based on a representative set of reflectance spectra that is used to calculate a special basic collection of device metameric blacks and an appropriate fundamental metamer for each sensor response. Combining the fundamental metamer and the basic collection results in a set of reflectances that follows the density distribution of metameric reflectances if calculated by Bayesian inference. Transforming only positive and bounded spectra of the set into an observer’s perceptually uniform color space results in a point cloud that follows the density distribution of device metamers within the metamer mismatch space of acqcuisition system and human observer. The mean value of this set is selected for color correction, since this is the point with a minimal mean color distance to all other points in the cloud. We present the results of various simulation experiments considering different acquisition and viewing illuminants, sensor types, noise levels, and existing methods for comparison.     

A Rank Encoder: Adaptive Analog to Digital Conversion Exploiting Time Domain Spike Signal Processing

An electronic circuit is presented that encodes an array of analog input signals into a digital number. The digital output is a rank order code that reflects the relative strength of the inputs, but is independent of the absolute input intensities. In that sense, the circuit performs an adaptive analog to digital conversion, adapting to the average intensity of the inputs (i.e. effectively normalizing) and adapting the quantization levels to the spread of the inputs. Thus, it can convey essential information with a minimal amount of output bits over a huge range of input signals.As a first processing step the analog inputs are projected into the time domain, i.e. into voltage spikes. The latency of those spikes encodes the strength of the input. This conversion enables the circuit to conduct further analog processing steps by asynchronous logic.     

Some observations of the effects of intertrial interval and delay on delayed matching to sample in pigeons.

Accuracy of delayed matching to sample was studied in 12 Silver King pigeons at different combinations of length of intertrial interval (ITI) and length of delay. When ITI and delay were varied between sessions in Exps I and II, accuracy increased monotonically with ITI and decreased monotonically with delay. Evidence was found for constancy of performance at equivalent ratios of ITI to delay, and percentage of correct choices was linearly related to the log of this ratio. In Exps III and IV, ITI was manipulated as a within-sessions variable. In contrast to the effect of this variable when manipulated between sessions, accuracy improved only from the shortest interval to the next shortest interval and remained constant at all longer intervals. In Exp IV, it was found that performance improved as a direct function of the mean ITI for sessions and that this relation was not affected by the degree of ITI variability within sessions. Findings resemble the effects of temporal variables on autoshaping, and the possibility that some common processes are involved in delayed matching and autoshaping is discussed. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Femtosecond broadband stimulated Raman: a new approach for high-performance vibrational spectroscopy

Femtosecond stimulated Raman spectroscopy (FSRS) is a new technique that produces high-quality vibrational spectra free from background fluorescence. FSRS combines a narrow-bandwidth picosecond Raman pump pulse with an approximately 80 fs continuum probe pulse to produce stimulated Raman spectra from the pump-induced gain in the probe spectrum. The high intensity of the Raman pump combined with the broad bandwidth of the probe produces high signal-to-noise vibrational spectra with very short data acquisition times. FSRS spectra of standard solutions and solvents such as aqueous Na2SO4, aqueous KNO3, methanol, isopropanol, and cyclohexane are collected in seconds. Furthermore, stimulated Raman spectra can be obtained using just a single pump-probe pulse pair that illuminates the sample for only approximately 1 ps. Fluorescence rejection is demonstrated by collecting FSRS spectra of dyes (rhodamine 6G, chlorophyll a, and DTTCI) with varying degrees of fluorescence background and resonance enhancement. The high signal-to-noise, short data acquisition time, fluorescence rejection, and high spectral and temporal resolution of femtosecond stimulated Raman spectroscopy make it a valuable new vibrational spectroscopic technique.     

Influence of spatial coherence on scattering by a particle

We analyze the effect of partial spatial coherence on the scattering of light by an arbitrary particle. We extend the definition of the extinction cross section to spatially partially coherent fields. We then discuss the effect of the partial coherence on the extinction scattering cross section by introducing the Wigner transform. It is shown that for rotationally invariant scatterers, the extinction cross section does not depend on the coherence of the incident field. The effect of partial coherence on the angular behavior of the scattered intensity is also discussed in the framework of the Wigner transform. The implications for practical applications are considered.     

Response selection and response execution in task switching: Evidence from a go-signal paradigm.

The present study used a go/no-go signal delay (GSD) to explore the role of response-related processes in task switching. A go/no-go signal was presented at either 100 ms or 1,500 ms after the stimulus. Participants were encouraged to use the GSD for response selection and preparation. The data indicate that the opportunity to select and prepare a response (i.e., long GSD) resulted in a substantial reduction of task-shift costs (Experiment 1) and n-2 task-repetition costs (i.e., backward inhibition; Experiment 2) in the current trial. These results suggest that interference from the preceding trial can be resolved during response selection and preparation. Furthermore, the shift costs and the n-2 repetition costs after no-go trials with long GSD (i.e., response selection but no execution) were markedly smaller than after go trials. These findings suggest that the interference that gives rise to shift costs and n-2 repetition costs is related not solely to response selection but also to response execution. Thus, the present study demonstrates dissociable contributions of response selection and response execution to interference effects in task switching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)