Scanning Probe Microscopy Facility for Operando Study of Redox Processes on Lithium ion Battery Electrodes.

An Atomic Force Microscope (AFM) is combined with a special designed glovebox system and coupled to a Galvanostat/Potentiostat to allow measurements on electrochemical properties for battery research. An open cell design with electrical contacts makes it possible to reach the electrode surface with the cantilever so as to perform measurements during battery operation. A combined AFM-Scanning Electro-Chemical Microscopy (AFM-SECM) approach makes it possible to simultaneously obtain topological information and electrochemical activity. Several methods have been explored to provide the probe tip with an amount of lithium so that it can be used as an active element in a measurement. The "wet methods" that use liquid electrolyte appear to have significant drawbacks compared to dry methods, in which no electrolyte is used. Two dry methods were found to be best applicable, with one method applying metallic lithium to the tip and the second method forming an alloy with the silicon of the tip. The amount of lithium applied to the tip was measured by determining the shift of the resonance frequency which makes it possible to follow the lithiation process. A FEM-based probe model has been used to simulate this shift due to mass change. The AFM-Galvanostat/Potentiostat set-up is used to perform electrochemical measurements. Initial measurements with lithiated probes show that we are able to follow ion currents between tip and sample and perform an electrochemical impedance analysis in absence of an interfering Redox-probe. The active probe method developed in this way can be extended to techniques in which AFM measurements can be combined with mapping electrochemical processes with a spatial resolution.

In-vivo tongue stiffness measured by aspiration: Resting vs general anesthesia.

Tongue cancer treatment often results in impaired speech, swallowing, or mastication. Simulating the effect of treatments can help the patient and the treating physician to understand the effects and impact of the intervention. To simulate deformations of the tongue, identifying accurate mechanical properties of tissue is essential. However, not many succeeded in characterizing in-vivo tongue stiffness. Those who did, measured the tongue At Rest (AR), in which muscle tone subsides even if muscles are not willingly activated. We expected to find an absolute rest state in participants 'under General Anesthesia' (GA). We elaborated on previous work by measuring the mechanical behavior of the in-vivo tongue under aspiration using an improved volume-based method. Using this technique, 5 to 7 measurements were performed on 10 participants both AR and under GA. The obtained Pressure-Shape curves were first analyzed using the initial slope and its variations. Hereafter, an inverse Finite Element Analysis (FEA) was applied to identify the mechanical parameters using the Yeoh, Gent, and Ogden hyperelastic models. The measurements AR provided a mean Young's Modulus of 1638 Pa (min 1035 - max 2019) using the Yeoh constitutive model, which is in line with previous ex-vivo measurements. However, while hoping to find a rest state under GA, the tongue unexpectedly appeared to be approximately 2 to 2.5 times stiffer under GA than AR. Explanations for this were sought by examining drugs administered during GA, blood flow, perfusion, and upper airway reflexes, but neither of these explanations could be confirmed.

Disinfection of Pythium-infested recirculation water by UV-oxidation technology.

Selective disinfection against Pythium aphanidermatum in recirculation water was tested with UV-irradiation and with UV-oxidation technology with the objective to reduce the electrical energy consumption per cubic meter treated water. UV-oxidation technology is based on injection of hydrogen peroxide in recirculation water, just before passage along a UV-lamp, thus creating hydroxyl radicals. Pythium aphanidermatum was applied artificially to recirculation water from tomatoes, grown, in rockwool and coconut fibre. Other parameters in this study were pH and transmission value (T10) of the infested recirculation water. Results indicated that the recommended UV-C dose of 100 mJ/cm2 for elimination of fungal pathogens in general can be lowered in case recirculation water is infected with Pythium aphanidermatum only. When UV-oxidation technology was applied with 1 mmol hydrogen peroxide per litre recirculation water, the UV-C dose could be reduced even more in comparison with merely UV irradiation.

[Complete recovery following hemorrhagic shock-encephalopathy syndrome]. / Volledig herstel na hemorragische-shock-encefalopathiesyndroom.

Haemorrhagic shock and encephalopathy (HSE) is a syndrome of unknown aetiology with a high mortality. Until recently, all survivors of HSE were reported to have severe neurological damage. We report the case of a 2-year-old boy who recovered completely from HSE. It is possible that the absence of so-called 'electrical storms' in the acute phase electroencephalogram is a prognostically favourable sign with respect to the neurological outcome.

Assessing the evolution of the evoked potential average: a new color display method.

A new method to control the averaging process and to check the stability of evoked potential (EP) components is described. The principle of the method is based on the display of the consecutive averages of the EP after each stimulus in a color-coded picture. In this way the evolution of the process is visualised instead of only the last average. The colors are assigned according to the amplitudes. The resulting picture initially consists of erratic colors. However, with increasing numbers of stimuli, tracks of one color soon emerge, indicating stable components. The number of stimuli necessary to generate a stable peak and the duration of stability can easily be quantified. Details with regard to the methods of extraction of essential data and data compression to record the picture are described. The color display method was evaluated with the analysis of 18 somatosensory evoked potentials and 17 visual evoked potentials of controls and 33 EPs of 18 patients. It is shown that this method preserves essential information about the averaging process: the stability of the EP components can be quantified and consequently the optimum number of stimuli to be applied. Furthermore, 14 of the 33 patient recordings showed artifacts, which could be traced with the average-evolution method, but not from the final average alone.

Signs of focal posterior cerebral abnormality in early subacute sclerosing panencephalitis.

In 16 cases of subacute sclerosing panencephalitis (SSPE), praxis and visual spatial capacities were more impaired early in the disease than were language functions. Together with the electroencephalographic findings, this suggests that the early lesions in SSPE are more pronounced in the parietooccipital area than in the classic language areas. Other reports also support such a localization. Detection of the disease in its early phase when dressing apraxia and visual impairment predominate is important in conducting clinical trials of different therapeutic agents.

The 'flight of colours' test in multiple sclerosis, retrobulbar neuritis and healthy controls.

The results of the test for afterimages ('flight of colours'; FOC) in healthy controls, MS patients and persons with a history of retrobulbar neuritis are presented. The FOC proved to be a reliable test of involvement of the visual system in these diseases. This concerns the duration of the afterimages as well as the palette of colours. The results were in accordance with those of the VEP, provided patients with a retrobulbar neuritis more than three years ago were omitted. In these persons the FOC proved to be more sensitive than the flash-VEP in detecting old lesions. It was concluded that these methods measure different aspects of the visual system.

An electroencephalographic study of 4-aminopyridine.

The electroencephalographic (EEG) effects of 4-aminopyridine (4-AP) given intravenously in therapeutic doses were studied in four conscious human volunteers. 4-AP (0.2 mg/kg) caused an increase of the occipital alpha peak frequency of 0.4 to 1.0 Hz. In the dose range of 0.2 to 0.3 mg/kg there was neither evidence for epileptic activity in the EEG nor were any clinical side effects observed. This dose of 4-AP was also found to antagonize diazepam-induced sleep in four volunteers. In addition 4-AP (0.3 mg/kg) hastened the recovery by a factor of 4 in four patients having endoscopic procedures under diazepam-nitrous oxide anesthesia.