The shear viscosity of carbon fibre suspension and its application for fibre length measurement

The viscosity of short carbon fibre suspensions in glycerol aqueous solution was measured using a bespoke vane-in-cup viscometer, where the carbon fibre has an aspect ratio from 450 to 2209. In the semi-concentrated regime, nL3 ranging from 20 to 4400, the suspensions demonstrated strong shear-thinning characteristics particularly at higher concentrations. The shear-thinning characteristic is strongly related to the crowding factor proposed by Kerekes, indicating that non-hydrodynamic interactions occur in the suspensions. The influence of fibre bending on viscosity emerges when the bending ratio is lower than 0.0028. An empirical model based on transient network formation and rupture was proposed and used to correlate the relative viscosity with fibre concentration nL3 and shear rate. Based on the model, a viscosity method is established to analyse the fibre length by measuring the viscosity of the fibre suspension using a bespoke vane-in-cup viscometer

The binding of cellulase variants to dislocations: a semi-quantitative analysis based on CLSM (confocal laser scanning microscopy) images

\ua9 2015, Hidayat et al. Binding of enzymes to the substrate is the first step in enzymatic hydrolysis of lignocellulose, a key process within biorefining. During this process elongated plant cells such as fibers and tracheids have been found to break into segments at irregular cell wall regions known as dislocations or slip planes. Here we study whether cellulases bind to dislocations to a higher extent than to the surrounding cell wall. The binding of fluorescently labelled cellobiohydrolases and endoglucanases to filter paper fibers was investigated using confocal laser scanning microscopy and a ratiometric method was developed to assess and quantify the abundance of the binding of cellulases to dislocations as compared to the surrounding cell wall. Only Humicola insolens EGV was found to have stronger binding preference to dislocations than to the surrounding cell wall, while no difference in binding affinity was seen for any of the other cellulose variants included in the study (H. insolens EGV variants, Trichoderma reesei CBHI, CBHII and EGII). This result favours the hypothesis that fibers break at dislocations during the initial phase of hydrolysis mostly due to mechanical failure rather than as a result of faster degradation at these locations

Disorders of Consciousness

The concept of consciousness has fascinated philosophers, psychologists and neurophysiologists for a long time; however, it remains difficult to give its univocal and universally accepted definition. Consciousness is defined as “the state of full awareness of the self and one’s relationship to the environment”; consequently, a distinction must be made between consciousness (or awareness) and vigilance/alertness (wakefulness). In fact, it is possible for a patient to be conscious, but unresponsive to the examiner, for lack of sensory inputs or for psychiatric reasons. Conversely, a subject can be alert and awake with open eyes, but not conscious and not aware (in part or at all) of itself and of the environment. From a neurophysiological point of view, it has been demonstrated that the brainstem Reticular Activating System (RAS) is responsible for the state of alertness, through its projections to the thalamus and cortex. The integrity of the upper cortical centres, which are closely related to each other and receive the reticular activating stimuli, is also essential for the maintenance of consciousness level. Therefore, Disorders Of Consciousness (DOC) and vigilance may depend on damage to one or both of these neurofunctional systems, acute or chronic, reversible or irreversible. Serious damage to the reticular system, with or without concomitant widespread cortical damage, can produce a state of coma. Coma is then a pathological condition in which the subject lies with eyes closed and he is neither conscious nor alert, with altered - or completely absent - responsiveness to stimuli. In case of widespread damage to the cerebral cortex without involvement of the RAS, a particular condition - named Vegetative State (VS) - may occur: the consciousness of self and of the environment is impaired, but a certain level of vigilance is still preserved. Moreover, there also exist several neurological conditions that can be defined as “borderline”, such as the Minimally Conscious State. Finally, brain death is the irreversible definitive impairment of both the cortical and brainstem functions. Electroencephalography is an important diagnostic and prognostic tool, useful to better characterise the evolution of a coma state, to recognise any kind of epileptiform activity - that could be clinically hidden - and to monitor the effects of antiepileptic drugs, level of sedation, and treatment of intracranial hypertension