In situ X-ray absorption spectroscopy at the K-edge of red phosphorus in polyamide 6,6 during a thermo-oxidative degradation

We present a new method for studying the influence of flame retardants as a function of time and temperature by measuring the X-ray absorption spectra of the corresponding additive. Here, red phosphorus in polyamide 6,6 was investigated at the phosphorus K-edge using synchrotron radiation. The thermo-oxidative degradation of the polymer was simulated by heating the sample up to 300°C. XANES

1 XANES, EXAFS: X-ray absorption spectroscopy investigating the near edge structure or the fine structure of the extended region, respectively.

spectra were monitored during the degradation process at different temperatures and at a constant reaction temperature as a function of time. The degradation reaction was analyzed by comparing the XANES spectra of red phosphorus and orthophosphoric acid, and the reaction was identified as an oxidation of red phosphorus to H₃PO₄. The results so obtained are confirmed by the EXAFS spectra of the additive in the polymer sample recorded before and after the thermo-oxidative degradation process, and by the EXAFS spectra of suitable reference compounds.     

The role of diabetes mellitus on the formation of severe odontogenic abscesses—a retrospective study

Objectives

To analyze the correlation of diabetes mellitus and hyperglycemia with severe odontogenic abscesses.

Materials and methods

Records of all patients in the Department of Oral and Maxillofacial Surgery of the Medical Center of the Johannes Gutenberg-University who underwent inpatient treatment for severe odontogenic abscesses between 2010 and 2016 were evaluated retrospectively regarding diabetes anamnesis, maximum and fasting blood sugar count, and duration until discharge. In order to compare the numbers to a general maxillofacial group, all patients who received inpatient treatment in 2013 for any diagnosis other than an abscess of the head and neck region were analyzed as well, and the numbers were correlated.

Results

In total, 977 abscess patients were found in the analyzed period. 7.0% of the patients had a known diagnosis of diabetes mellitus type II and 0.6% of type I. Correlation with the general group showed that abscesses were significantly more likely in diabetics as well as patients with abnormal maximum and fasting blood sugar counts. These patients also needed significantly longer inpatient treatment.

Conclusions

Diabetics and patients with abnormal glucose tolerance show significantly higher numbers of severe odontogenic abscesses and might therefore benefit from earlier escalation of antibiotic medication.

Clinical relevance

Severe odontogenic abscesses are one of the most frequent diagnoses in maxillofacial practice. Adjusting the therapeutic approach for diabetics or patients with abnormal blood sugar counts might help to prevent the development of abscesses.

     

Comparison of hydraulic and hemolytic properties of different impeller designs of an implantable rotary blood pump by computational fluid dynamics

A mixed-flow blood pump for long-term applications has been developed at the Helmholtz-Institute in Aachen, Germany. Central features of this implantable pump are a centrally integrated motor, a blood-immersed mechanical bearing, magnetic coupling of the impeller, and a shrouded impeller, which allows a relatively wide clearance. The aim of the study was a numerical analysis of hydraulic and hemolytic properties of different impeller design configurations. In vitro testing and numerical simulation techniques (computational fluid dynamics [CFD]) were applied to achieve a comprehensive overview. Pressure-flow charts were experimentally measured in a mock loop in order to validate the CFD data. In vitro hemolysis tests were performed at the main operating point of each impeller design. General flow patterns, pressure-flow charts, secondary flow rates, torque, and axial forces on the impeller were calculated by means of CFD. Furthermore, based on streak line techniques, shear stress (stress loading), exposure times, and volume percentage with critical stress loading have been determined. Comparison of CFD data with pressure head measurements showed excel-lent agreement. Also, impressive trend conformity was observed between in-vitro hemolysis results and numerical data. Comparison of design variations yielded clear trends and results. Design C revealed the best hydraulic and hemolytic properties and was chosen as the final design for the mixed-flow rotary blood pump.     

Changes in the Body Image and Relationship Scale following a one-year strength training trial for breast cancer survivors with or at risk for lymphedema

The aim of this study was to evaluate the impact of a twice-weekly strength training intervention on perceptions of body image in 234 breast cancer survivors (112 with lymphedema) who participated in the Physical Activity and Lymphedema (PAL) trial. The study population included two hundred and thirty-four women randomly assigned to twice-weekly strength training or control group that completed the 32-item Body Image and Relationships Scale (BIRS) at baseline and 12 months. Percent change in baseline to 12-month BIRS total and subscale scores, upper and lower body strength, and general quality of life (QOL) were compared by intervention status. A series of multiple linear regression models including indicator variables for subgroups based on age, marital status, race, education, BMI, and strength change were used to examine differential intervention impact by subgroup. Strength and QOL variables were assessed as mediators of the intervention effect on BIRS. Results: Baseline BIRS scores were similar across intervention and lymphedema status. Significantly greater improvement in BIRS total score was observed from baseline to 12 months in treatment vs. control participants (12.0 vs. 2.0%; P < 0.0001). A differential impact of the intervention on the Strength and Health subscale was observed for older women (>50 years old) in the treatment group (P = 0.03). Significantly greater improvement was observed in bench and leg press among treatment group when compared to control group participants, regardless of lymphedema. Observed intervention effects were independent of observed strength and QOL changes. Twice-weekly strength training positively impacted self-perceptions of appearance, health, physical strength, sexuality, relationships, and social functioning. Evidence suggests the intervention was beneficial regardless of prior diagnosis of lymphedema. Strength and QOL improvements did not mediate the observed intervention effects.     

A validated CFD model to predict O₂ and CO₂ transfer within hollow fiber membrane oxygenators

Hollow fiber oxygenators provide gas exchange to and from the blood during heart surgery or lung recovery. Minimal fiber surface area and optimal gas exchange rate may be achieved by optimization of hollow fiber shape and orientation (1). In this study, a modified CFD model is developed and validated with a specially developed micro membrane oxygenator (MicroMox). The MicroMox was designed in such a way that fiber arrangement and bundle geometry are highly reproducible and potential flow channeling is avoided, which is important for the validation. Its small size (V(Fluid)=0.04 mL) allows the simulation of the entire bundle of 120 fibers. A non-Newtonian blood model was used as simulation fluid. Physical solubility and chemical bond of O? and CO? in blood was represented by the numerical model. Constant oxygen partial pressure at the pores of the fibers and a steady state flow field was used to calculate the mass transport. In order to resolve the entire MicroMox fiber bundle, the mass transport was simulated for symmetric geometry sections in flow direction. In vitro validation was achieved by measurements of the gas transfer rates of the MicroMox. All measurements were performed according to DIN EN 12022 (2) using porcine blood. The numerical simulation of the mass transfer showed good agreement with the experimental data for different mass flows and constant inlet partial pressures. Good agreement could be achieved for two different fiber configurations. Thus, it was possible to establish a validated model for the prediction of gas exchange in hollow fiber oxygenators.     

Toluene abuse causes diffuse central nervous system white matter changes

We describe the findings of magnetic resonance imaging (MRI) of the brain in 6 chronic toluene vapor abusers and the neuropathological findings in 1 abuser not studied by MRI. MRI in 6 chronic toluene abusers revealed the following abnormalities: (1) diffuse cerebral, cerebellar, and brainstem atrophy; (2) loss of differentiation between the gray and white matter throughout the central nervous system; and (3) increased periventricular white matter signal intensity on T2-weighted images. Another chronic toluene abuser (MRI not performed) died as a result of acute toluene overdose. The brain displayed diffuse, ill-defined myelin pallor, maximal in cerebellar, periventricular, and deep cerebral white matter. Neurons were preserved throughout, axonal swelling or beading was not seen, gliosis was minimal, and occasional, scant perivascular macrophage collections were seen. Taken in concert, these findings suggest that the pathological and MRI abnormalities are due to either increased water content of the white matter or subtle toluene-induced metabolic changes in myelin.     

The temporal dynamics of ambivalence: changes in positive and negative affect in relation to consumption of an "emotionally charged" food

Ambivalence is thought to impact consumption of food, alcohol and drugs, possibly via influences on craving, with cravers often being simultaneously drawn toward and repelled from ingestion. So far, little is known about the temporal dynamics of ambivalence, especially as it varies in relationship to consumption. Participants (n = 482, 56.8% female) completed the Positive and Negative Affect Schedule prior to, immediately and 30 min after the opportunity to eat a bar of chocolate. Affective ambivalence was calculated based on the relative strengths of and discrepancy between ratings of positive and negative affect. Ambivalence peaked prior to a decision about consumption and subsequently decreased, whether or not the decision was in favor of or against consuming. Decreasing ambivalence was driven by a drop in positive affect over time; positivity decreased more rapidly in those who consumed chocolate. Findings represent a first step in characterizing the dynamics of ambivalence in interactions with a target stimulus.     

Transient, three-dimensional flow field simulation through a mechanical, trileaflet heart valve prosthesis

Thromboembolic complications are one of the major challenges faced by designers and researchers in development of artificial organs with blood-contacting devices such as heart valve prostheses, especially mechanical valves. Besides increasing the thrombogenic potential, these valves change the hydrodynamic performance of the heart. In this study, the flow through a trileaflet, mechanical heart valve prosthesis was modeled with transient computational fluid dynamics to analyze flow patterns causing thrombus formations on valves. The valve was simulated under conditions of a test rig (THIA II), which was specially designed to analyze different valves with respect to thrombosis. The main goal of this study was to mimic the exact conditions of the test rig to be able to compare numerical and experimental results. The boundary conditions were obtained from experimental data as leaflet kinematics and pressure profiles. One complete cycle of the valve was simulated. Numerical flow and pressure results were analyzed and compared with experimental results. Shear stress and shear rates were determined with respect to thrombogenic potential, especially in the pivot regions, which seem to be the main influence for activation and deposition of thrombocytes. Approximately 0.7% of the blood volume moving through the fluid domain of the valve was exposed to shear rates high enough to cause platelet activation. However, shear rates of up to 20,000 s?1 occurred in pivot regions. The pressure differences between the simulation and experimental data were approximately 2.5% during systole and increased up to 25% during diastole. The presented method, however, can be used to gain more information about the flow through different heart valve prostheses and, thus, improve the development process.