A novel method for the fabrication of freestanding PZT features on substrates

A simple and cheap micromoulding fabrication route was developed to prepare freestanding piezo active features. Dimensions as small as 200 μm by 200 μm and 40 μm high were successfully fabricated via a replication technique. The lead zirconate titanate features were thoroughly characterized using SEM, EDX and XRD analysis. The properties of the features were influenced by several factors like the type of substrate, sintering temperature and sintering atmosphere. Features prepared on alumina substrates and sintered in lead atmosphere displayed a structure with reproducible dimensions. Next to that they were low in porosity and had a comparable composition with respect to the starting powder. The remanent polarization of the lead zirconate film was 12.3 μC/cm2 and the coercive field was 8.7 kV/cm

Planning and control in a manual collision avoidance task by children with hemiparesis

We examined whether deficits in planning and control during a manual collision avoidance task in children with hemiparesis are associated with damage to the left or right hemisphere (LHD and RHD). Children pushed a doll across a scale-size road between two approaching toy cars. Movement onset and velocity served as indicators of planning and control. In Experiment 1, children with hemiparesis collided more frequently, and controlled velocity less appropriately compared to typically-developing children. Children with LHD initiated their movement later than children with RHD. Experiment 2 compared the preferred and non-preferred hand of children with LHD and RHD. Children with RHD crossed less with their non-preferred hand, while children with LHD initiated later than children with RHD. Moreover, the groups showed differences in velocity control. It is argued that planning deficits may be related to LHD. The hypothesized association between control deficits and RHD, however, was not confirmed

Measurement of the effect of a bolus does of intrathecal baclofen by a repetitive movement test

We assessed the repetitive movement (RM) test for measuring the effect of a trial bolus dose of intrathecal baclofen on spasticity. The RM test measures passive range of motion (ROM) by electrogoniometry and stretch reflex activity (SRA) of the flexors and extensors of the knee and ankle by surface electromyography. The SRA has a dynamic component (dynamic stretch reflex, DSR) and a tonic component (tonic stretch reflex, TSR). Four hypotheses were formulated: (a) RM results show a negative relationship between SRA and ROM; (b) values on the RM test are correlated with clinical scores of tonus and spasticity; (c) RM results show a reduction in SRA after administration of the clinically optimal dose of baclofen; and (d) RM results show a dose-dependent effect of intrathecal baclofen on SRA. Twenty-four patients were selected because they had impairments and disabilities caused by intractable spasticity. A bolus of baclofen was administered with incremental doses (25-150 micrograms) until an optimal effect or no effect was obtained. The main outcome measures were RM test and clinical assessments of the Ashworth and spasm score. The results were (a) For the ankle a negative correlation was found between ROM and TSR of the flexor and extensors; for the knee a significant negative correlation was found only with the DSR of the biceps femoris. (b) A positive correlation was found between the Ashworth score and TSR of the extensors and between the spasm score and DSR and TSR of the gastrocnemius muscle. (c) Significant differences were found between baseline measurements and the optimal dose of baclofen for all measures. (d) A significant dose-dependent effect of intrathecal baclofen on the level of SRA was observed. The RM test is thus a useful clinical tool for objectively measuring the effect of intrathecal baclofen administration on spasticity in patients with an upper motor neuron syndrom

Bench scale demonstration of the Supermethanol concept: The synthesis of methanol from glycerol derived syngas

An integrated process for the synthesis of methanol from aqueous glycerol involving reforming of the feed to syngas followed by methanol synthesis is successfully demonstrated in a continuous bench scale unit. Glycerol reforming was carried out at pressures of 24–27 MPa and temperatures of 948–998 K with a throughput of approximately 1 kg aqueous feed/h (3–10 wt.% glycerol) leading to high glycerol conversions of (95.0–99.9%) and syngas with a composition range of H2/CO/CO2/CxHy = 44–67/1–21/16–34/2–18 vol.%. The effluent water of the process was recycled at high pressure, reducing the water consumption of the process significantly. Subsequent syngas conversion to methanol was carried out in a packed bed reactor at temperatures between 468 and 518 K and pressures between 24 and 27 MPa using a commercial methanol catalyst (Cu/ZnO/Al2O3). The maximum yield of methanol based on glycerol intake was 0.62 kg methanol/kg glycerol for an experiment with a time on stream of 16 h, which corresponds to a carbon conversion (carbon in methanol over carbon in glycerol) of 60%. This value is close to the maximum theoretical yield of 78% based on stoichiometric considerations.

Diagnostic accuracy of nocturnal oximetry for detection of sleep apnea syndrome in stroke rehabilitation

Background and Purpose—Sleep apnea syndrome (SAS) is a common sleep disorder in stroke patients and is associated with decreased recovery and increased risk of recurrent stroke and mortality. The standard diagnostic test for SAS is poly(somno)graphy, but this is often not feasible in stroke rehabilitation settings. This study investigated the diagnostic value of nocturnal oximetry for screening SAS in stroke rehabilitation. Methods—Fifty-six stroke patients underwent nocturnal polygraphy and oximetry. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index were calculated. Patient and sleep characteristics were used to develop a predictive model of apnea-hypopnea index. Results—Forty-six percent of the stroke patients had SAS. The majority of SAS patients was male, older, and had a higher body mass index than patients without SAS. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index ≥15 were, respectively, 77%, 100%, 100%, and 83%. Oxygen desaturation index predicted 87% of the variance in the apnea-hypopnea index. Patient characteristics did not add significantly to the prediction model. Conclusion—Nocturnal oximetry is an accurate diagnostic screening instrument for the detection of SAS in stroke patients

Can a prediction model combining self-reported symptoms, sociodemographic and clinical features serve as a reliable first screening method for sleep apnea syndrome in patients with stroke?

OBJECTIVE: To determine whether a prediction model combining self-reported symptoms, sociodemographic and clinical parameters could serve as a reliable first screening method in a step-by-step diagnostic approach to sleep apnea syndrome (SAS) in stroke rehabilitation. DESIGN: Retrospective study. SETTING: Rehabilitation center. PARTICIPANTS: Consecutive sample of patients with stroke (N=620) admitted between May 2007 and July 2012. Of these, 533 patients underwent SAS screening. In total, 438 patients met the inclusion and exclusion criteria. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We administered an SAS questionnaire consisting of self-reported symptoms and sociodemographic and clinical parameters. We performed nocturnal oximetry to determine the oxygen desaturation index (ODI). We classified patients with an ODI ≥15 as having a high likelihood of SAS. We built a prediction model using backward multivariate logistic regression and evaluated diagnostic accuracy using receiver operating characteristic analysis. We calculated sensitivity, specificity, and predictive values for different probability cutoffs. RESULTS: Thirty-one percent of patients had a high likelihood of SAS. The prediction model consisted of the following variables: sex, age, body mass index, and self-reported apneas and falling asleep during daytime. The diagnostic accuracy was .76. Using a low probability cutoff (0.1), the model was very sensitive (95%) but not specific (21%). At a high cutoff (0.6), the specificity increased to 97%, but the sensitivity dropped to 24%. A cutoff of 0.3 yielded almost equal sensitivity and specificity of 72% and 69%, respectively. Depending on the cutoff, positive predictive values ranged from 35% to 75%. CONCLUSIONS: The prediction model shows acceptable diagnostic accuracy for a high likelihood of SAS. Therefore, we conclude that the prediction model can serve as a reasonable first screening method in a stepped diagnostic approach to SAS in stroke rehabilitation

Methanol synthesis beyond chemical equilibrium

In commercial methanol production from syngas, the conversion is thermodynamically limited to 0.3–0.7 leading to large recycles of non-converted syngas. This problem can be overcome to a significant extent by in situ condensation of methanol during its synthesis which is possible nowadays due to the availability of highly active catalysts allowing for lower reactor temperatures. For the first time, in situ methanol condensation at 20 MPa and 473 K was demonstrated visually in a view cell. The condensation of reaction products (mainly methanol and water) drives the equilibrium reactions nearly to completion, as is demonstrated experimentally in a packed bed reactor and supported by thermodynamic calculations. Contrary to conventional methanol synthesis, once-through operation becomes possible avoiding recycling of unconverted syngas, which can be economically beneficial for industrial stakeholders.

Obstructive sleep apnea is related to impaired cognitive and functional status after stroke

Study Objectives: Obstructive sleep apnea (OSA) is a common sleep disorder in stroke patients and is associated with prolonged hospitalization, decreased functional outcome, and recurrent stroke. Research on the effect of OSA on cognitive functioning following stroke is scarce. The primary objective of this study was to compare stroke patients with and without OSA on cognitive and functional status upon admission to inpatient rehabilitation. Design: Case-control study. Setting and Patients: 147 stroke patients admitted to a neurorehabilitation unit. Interventions: N/A. Measurements: All patients underwent sleep examination for diagnosis of OSA. We assessed cognitive status by neuropsychological examination and functional status by two neurological scales and a measure of functional independence. Results: We included 80 stroke patients with OSA and 67 stroke patients without OSA. OSA patients were older and had a higher body mass index than patients without OSA. OSA patients performed worse on tests of attention, executive functioning, visuoperception, psychomotor ability, and intelligence than those without OSA. No differences were found for vigilance, memory, and language. OSA patients had a worse neurological status, lower functional independence scores, and a longer period of hospitalization in the neurorehabilitation unit than the patients without OSA. OSA status was not associated with stroke type or classification. Conclusions: Obstructive sleep apnea (OSA) is associated with a lower cognitive and functional status in patients admitted for stroke rehabilitation. This underlines the importance of OSA as a probable prognostic factor, and calls for well-designed randomized controlled trials to study its treatability