Hemicellulose hydrolysis catalysed by solid acids

Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reactions in water, under neutral pH and relatively mild temperature and pressure (120 °C and 10 bar) conditions. Sulphonated resins are highly active, but they leach out sulphonic groups. Sulphonated silicas are less active, but more stable. They have weakly and strongly bound sites and the strongly bound ones do not leach. Zeolites are moderately active and stable. Among them, H-ferrierite especially, despite its small pores, exhibited high activity as well as good recyclability

A brain electrophysiological correlate of depth perception

WOS: 000267097600006PubMed ID: 21048598Objectives: To investigate brain electrical activity accompanying depth perception using random-dot stereograms. Additional experiments were conducted to ascertain the specificity of this potential to depth perception. Methods: In the present study, we performed 3 different and independent experiments on 34 subjects to establish the relationship between depth perception and its cortical electrophysiological correlate. Visual evoked potentials in response to visual stimulation by random-dot stereograms were recorded. To achieve this goal, a data acquisition and analysis system, different from common visual evoked potential recording systems, consisting of 2 personal computers, was used. One of the computers was used to generate the visual stimulus patterns and the other to record and digitally average the potentials evoked by the stimuli. This study was carried out at the Department of Biophysics of Ege University Medical School, Izmir, Turkey, from April to December, 2006. Results: A negative potential component, which is thought to arise in association with depth perception, was recorded from the occipital region from 30 of the 34 subjects. Typically, it had a mean latency of 211.46 ms and 6.40 mu V amplitude. Conclusion: The negative potential is related to depth perception, as this component is present in the responses to stimulus, which carries disparity information but is absent when the stimulus is switched to no disparity information. Additional experiments also showed that the specificity of this component to depth perception becomes evident beyond doubt

Depth perception differences between hemispheres, genders, and eye dominance A study on evoked potential

WOS: 000272665500026BACKGROUND: Certain neural functions, such as peripheral reflexes, differ between genders, while higher brain functions, such as language, are asymmetrically distributed between the two hemispheres. The question remains as to whether depth perception differs between hemispheric laterality and genders, and whether it is affected by eye dominance. OBJECTIVE: To determine whether depth perception is influenced by factors such as gender, eye dominance, and hemispheric lateralization by recording evoked potential associated with depth perception. DESIGN, TIME AND SETTING: A contrast observation based on neuroelectrophysiology was performed at the Department of Biophysics of Ege University Medical School between June 2006 and April 2007. PARTICIPANTS: A total of 34 subjects, 19 females and 15 males, were included in the study with a mean age of (31.0 +/- 6.9) years. All subjects were free of neurological or psychological disorders, or problems such as strabismus or vision correction. METHODS: Random-dot stereograms were used to elicit brain activity. A specially designed signal acquisition system employing two computers was used to record evoked potentials from both hemispheres via two pairs of scalp electrodes placed over the occipitotemporal areas of both hemispheres at symmetrical locations. MAIN OUTCOME MEASURES: Negative potential with a mean latency of (211.21 +/- 25.55) ms and a mean amplitude of (6.05 +/- 1.53) mu V was recorded from both occipitotemporal areas in 30 out of 34 participants. This was termed "N(d)" and represented the evoked potential associated with depth perception. RESULTS: There were no significant differences in N(d) amplitude or latency between the two hemispheres, the two eyes, or genders (P > 0.05). CONCLUSION: The evoked potential associated with depth perception was not influenced by gender, hemisphere, or eye dominance