Derivation of the stress-strain behavior of the constituents of bio-inspired layered TiO2/PE-nanocomposites by inverse modeling based on FE-simulations of nanoindentation test.

Owing to the apparent simple morphology and peculiar properties, nacre, an iridescent layer, coating of the inner part of mollusk shells, has attracted considerable attention of biologists, material scientists and engineers. The basic structural motif in nacre is the assembly of oriented plate-like aragonite crystals with a 'brick' (CaCO3 crystals) and 'mortar' (macromolecular components like proteins) organization. Many scientific researchers recognize that such structures are associated with the excellent mechanical properties of nacre and biomimetic strategies have been proposed to produce new layered nanocomposites. During the past years, increasing efforts have been devoted towards exploiting nacre's structural design principle in the synthesis of novel nanocomposites. However, the direct transfer of nacre's architecture to an artificial inorganic material has not been achieved yet. In the present contribution we report on laminated architecture, composed of the inorganic oxide (TiO2) and organic polyelectrolyte (PE) layers which fulfill this task. To get a better insight and understanding concerning the mechanical behaviour of bio-inspired layered materials consisting of oxide ceramics and organic layers, the elastic-plastic properties of titanium dioxide and organic polyelectrolyte phase are determined via FE-modelling of the nanoindentation process. With the use of inverse modeling and based on numerical models which are applied on the microscopic scale, the material properties of the constituents are derived.

[Dynamic contrast-enhanced MRI of the prostate: comparison of two different post-processing algorithms]. / Dynamische kontrastmittelunterstützte MRT der Prostata: Vergleich von zwei Auswerteverfahren.

PURPOSE: To evaluate the usefulness of a commercially available post-processing software tool for detecting prostate cancer on dynamic contrast-enhanced magnetic resonance imaging (MRI) and to compare the results to those obtained with a custom-made post-processing algorithm already tested under clinical conditions. MATERIALS AND METHODS: Forty-eight patients with proven prostate cancer were examined by standard MRI supplemented by dynamic contrast-enhanced dual susceptibility contrast (DCE-DSC) MRI prior to prostatectomy. A custom-made post-processing algorithm was used to analyze the MRI data sets and the results were compared to those obtained using a post-processing algorithm from In vivo Corporation (Dyna CAD for Prostate) applied to dynamic T 1-weighted images. Histology was used as the gold standard. RESULTS: The sensitivity for prostate cancer detection was 78 % for the custom-made algorithm and 60 % for the commercial algorithm and the specificity was 79 % and 82 %, respectively. The accuracy was 79 % for our algorithm and 77.5 % for the commercial software tool. The chi-square test (McNemar-Bowker test) yielded no significant differences between the two tools (p = 0.06). CONCLUSION: The two investigated post-processing algorithms did not differ in terms of prostate cancer detection. The commercially available software tool allows reliable and fast analysis of dynamic contrast-enhanced MRI for the detection of prostate cancer.

Brugada syndrome following tricyclic antidepressant overdose.

The Brugada syndrome, a pro-arrhythmogenic repolarization abnormality, is becoming increasingly recognised as a cause of collapse and sudden cardiac death. We report a case of a 48-year-old man with a tricyclic overdose and a delayed presentation of the Brugada pattern in the ICU. This case raises the need for clinicians to be aware of the Brugada pattern and those patients potentially at risk.

Rewarming of healthy volunteers after induced mild hypothermia: a healthy volunteer study.

OBJECTIVES: The study compares the efficacy of two active and one passive warming interventions in healthy volunteers with induced mild hypothermia. METHODS: Eight volunteers were studied in a random order crossover design. Each volunteer was studied during re-warming from a core temperature of 35 degrees C with each of: a radiant warmer (Fisher & Paykel); a forced air warmer (Augustine Medical), and a polyester filled blanket, to re-warm. RESULTS: No significant differences in re-warming rates were observed between the three warming devices. It was found that the subject's endogenous heat production was the major contributor to the re-warming of these volunteers. Metabolic rates of over 350 W were seen during the study. CONCLUSIONS: For patients with mild hypothermia and in whom shivering is not contraindicated our data would indicate that the rate of re-warming would be little different whether a blanket or one of the two active devices were used. In the field, this may provide the caregiver a useful choice.

Relationship between the humidity and temperature of inspired gas and the function of the airway mucosa.

OBJECTIVE: To review the available literature on the relationship between the humidity and temperature of inspired gas and airway mucosal function. DATA SOURCES: International computerized databases and published indices, experts in the field, conference proceedings, bibliographies. STUDY SELECTION/DATA EXTRACTION: Two hundred articles/texts on respiratory tract physiology and humidification were reviewed. Seventeen articles were selected from 40 articles for inclusion in the published data verification of the model. Selection was by independent reviewers. Extraction was by consensus, and was based on finding sufficient data. DATA SYNTHESIS: A relationship exists between inspired gas humidity and temperature, exposure time to a given humidity level, and mucosal function. This relationship can be modeled and represented as an inspired humidity magnitude vs. exposure time map. The model is predictive of mucosal function and can be partially verified by the available literature. It predicts that if inspired humidity deviates from an optimal level, a progressive mucosal dysfunction begins. The greater the humidity deviation, the faster the mucosal dysfunction progresses. CONCLUSIONS: A model for the relationship between airway mucosal dysfunction and the combination of the humidity of inspired gas and the duration over which the airway mucosa is exposed to that humidity is proposed. This model suggests that there is an optimal temperature and humidity above which, and below which, there is impaired mucosal function. This optimal level of temperature and humidity is core temperature and 100% relative humidity. However, existing data are only sufficient to test this model for gas conditions below core temperature and 100% relative humidity. These data concur with the model in that region. No studies have yet looked at this relationship beyond 24 hrs. Longer exposure times to any given level of inspired humidity and inspired gas temperatures and humidities above core temperature and 100% relative humidity need to be studied to fully verify the proposed model.

Arterial oxygen saturation during general anaesthesia for paediatric dental extractions.

Arterial oxygen saturation (SaO2) was measured in 50 healthy children undergoing dental extractions under general anaesthesia. An inhalational anaesthetic technique was employed, with an inspired oxygen concentration of 33%. There were decreases in SaO2 of greater than 5% of the baseline value in 70% of patients, and greater than 10% in 26% of patients. The majority of these decreases were associated with teeth extractions or during placement of dental prop and pack. Non-Caucasian children showed a significantly (p less than 0.05) greater maximum decrease in SaO2 from baseline value compared to Caucasian children. The maximum decreases in SaO2 from baseline value in children anaesthetised by supervised dental students, and in children whose extractions were performed by dental students, were significantly (p less than 0.05) greater than in children whose anaesthetic and surgery were performed by members of staff.