Beneficial effect of multi-wall carbon nanotubes on the graphitization of polyacrylonitrile (PAN) coating

Polyacrylonitrile (PAN) solutions were deposited on quartz plates by spin coating to yield 2–3 µm thick PAN films. The films were decomposed at 1000°C in N2 atmosphere into electrically conducting carbonaceous coatings. When the precursor solution contained cobalt (0.2 g Co-acetate per 1 g PAN) and/or multi-wall carbon nanotubes (MWCNTs, 2 mg MWCNT per 1 g PAN) the specific electrical resistance of the product film dropped from the original 492 Ω·cm-1 value down to 46 Ω·cm-1. By excluding all other possibilities we came to the conclusion that the beneficial effect of carbon nanotubes is related to their catalytic action in the final graphitization of condensed nitrogen-containing rings into graphitic nanocrystallites

Ultimate performance of Quantum Well Infrared Photodetectors in the tunneling regime

Thanks to their wavelength diversity and to their excellent uniformity, Quantum Well Infrared Photodetectors (QWIP) emerge as potential candidates for astronomical or defense applications in the very long wavelength infrared (VLWIR) spectral domain. However, these applications deal with very low backgrounds and are very stringent on dark current requirements. In this paper, we present the full electro-optical characterization of a 15 micrometer QWIP, with emphasis on the dark current measurements. Data exhibit striking features, such as a plateau regime in the IV curves at low temperature (4 to 25 K). We show that present theories fail to describe this phenomenon and establish the need for a fully microscopic approach

Absolute beat-to-beat variability and instability parameters of ECG intervals predict ischemia-induced ventricular fibrillation

Background: ECG interval measurement is possible during arrhythmias. Beat-to-beat variability and instability (BVI) of ECG intervals measured irrespective of rhythm (absolute BVI) predict drug-induced torsades de pointes (TdP) more accurately than the same variables derived exclusively during sinus rhythm (sinus BVI) in rabbits. We have tested whether this approach predicts another stochastic arrhythmia event, ventricular fibrillation (VF), in a different pathophysiological setting. Methods and Results: Langendorff perfused rat hearts were subjected to regional ischemia for 15 min. Absolute BVI parameters were derived from ECG intervals measured in 40 consecutive ventricular complexes (irrespective of the rhythm) immediately preceding VF onset and compared with values in time-matched ECGs in hearts that did not express VF. Increased frequency of non-sinus beats and ‘R on T’ arrhythmic beats, shortened mean RR and electrical diastolic intervals, and increased BVI of cycle length and repolarization were associated with VF occurrence. Absolute BVI parameters that quantify variability of repolarization (e.g. ‘short-term variability’ of QT interval) had the best predictive power with very high sensitivity and specificity. In contrast, VF was not predicted by any BVI parameter derived exclusively from sinus rhythm. Conclusions: The novel absolute BVI parameters that predicted TdP liability in rabbits also predict VF liability during regional ischemia in rat hearts, indicating a diagnostic and mechanistic congruence. Repolarization inhomogeneity appears to play a pivotal role in ischemic VF induction since absolute BVI parameters that quantify repolarization variability had outstanding predictive power

Abdominal Superficial Subcutaneous Fat

OBJECTIVE: Unlike visceral adipose tissue (VAT), the association between subcutaneous adipose tissue (SAT) and obesity-related morbidity is controversial. In patients with type 2 diabetes, we assessed whether this variability can be explained by a putative favorable, distinct association between abdominal superficial SAT (SSAT) (absolute amount or its proportion) and cardiometabolic parameters. RESEARCH DESIGN AND METHODS: We performed abdominal magnetic resonance imaging (MRI) in 73 patients with diabetes (mean age 58 years, 83% were men) and cross-sectionally analyzed fat distribution at S1-L5, L5-L4, and L3-L2 levels. Patients completed food frequency questionnaires, and subgroups had 24-h ambulatory blood pressure monitoring and 24-h ambulatory electrocardiography. RESULTS: Women had higher %SSAT (37 vs. 23% in men; P < 0.001) despite a similar mean waist circumference. Fasting plasma glucose (P = 0.046) and HbA1c (P = 0.006) were both lower with increased tertile of absolute SSAT. In regression models adjusted for age, waist circumference, and classes of medical treatments used in this patient population, increased %SSAT was significantly associated with decreased HbA1c (β = −0.317; P = 0.013), decreased daytime ambulatory blood pressure (β = −0.426; P = 0.008), and increased HDL cholesterol (β = 0.257; P = 0.042). In contrast, increased percent of deep SAT (DSAT) was associated with increased HbA1c (β = 0.266; P = 0.040) and poorer heart rate variability parameters (P = 0.030). Although total fat and energy intake were not correlated with fat tissue distribution, increased intake of trans fat tended to be associated with total SAT (r = 0.228; P = 0.05) and DSAT (r = 0.20; P = 0.093), but not with SSAT. CONCLUSIONS: Abdominal SAT is composed of two subdepots that associate differently with cardiometabolic parameters. Higher absolute and relative distribution of fat in abdominal SSAT may signify beneficial cardiometabolic effects in patients with type 2 diabetes

Communication and Technical Skills: The Role of The SBAR Technique and Microsurgery in Simulation-Based Surgical Education

The University of Szeged Clinical Skills Center describes the SBAR Technique for teaching the highly necessary but often neglected interpersonal skills crucial in emergency departments and during changing shifts at hospitals. The Clinical Skills Center also reveals the fascinating world of microsurgery, its prestigious labs and simulation-based surgery curriculum for professionals.Co-financed by the governments of Czechia, Hungary, Poland and Slovakia through Visegrad Grants from the International Visegrad Fund. The mission of the fund is to advance ideas for sustainable regional cooperation in Central Europe

Absolute beat-to-beat variability and instability parameters of ECG intervals: biomarkers for predicting ischaemia-induced ventricular fibrillation

Background and PurposePredicting lethal arrhythmia liability from beat-to-beat variability and instability (BVI) of the ECG intervals is a useful technique in drug assessment. Most investigators use only arrhythmia-free ECGs for this. Recently, it was shown that drug-induced torsades de pointes (TdP) liability can be predicted more accurately from BVI measured irrespective of rhythm, even during arrhythmias (absolute BVI). The present study tested the broader applicability of this assessment by examining whether absolute BVI parameters predict another potential lethal arrhythmia, ischaemia-induced ventricular fibrillation (VF).Experimental ApproachLangendorff-perfused rat hearts were subjected to regional ischaemia for 15 min. Absolute BVI parameters were derived from ECG intervals measured in 40 consecutive ventricular complexes (irrespective of rhythm) immediately preceding VF onset and compared with time-matched values in hearts not expressing VF.Key ResultsIncreased frequency of non-sinus beats and 'R on T' arrhythmic beats, shortened mean RR and electrical diastolic intervals, and increased BVI of cycle length and repolarization predicted VF occurrence. Absolute BVI parameters that quantify variability of repolarization (e.g. 'short-term variability' of QT interval) had the best predictive power with high sensitivity and specificity. In contrast, VF was not predicted by any BVI parameter derived from the last arrhythmia-free interlude before VF.Conclusions and ImplicationsThe novel absolute BVI parameters that predicted TdP in rabbit also predict ischaemia-induced VF in rat, indicating a diagnostic and mechanistic congruence. Repolarization inhomogeneity represents a pivotal biomarker of ischaemia-induced VF. The newly validated biomarkers could serve as surrogates for VF in pre-clinical drug investigations.</p

15-micro-m 128 x 128 GaAs/Al(x)Ga(1-x) As Quantum Well Infrared Photodetector Focal Plane Array Camera

In this paper, we discuss the development of very sensitive, very long wavelength infrared GaAs/Al(x)Ga(1-x)As quantum well infrared photodetectors (QWIP's) based on bound-to-quasi-bound intersubband transition, fabrication of random reflectors for efficient light coupling, and the demonstration of a 15 micro-m cutoff 128 x 128 focal plane array imaging camera. Excellent imagery, with a noise equivalent differential temperature (N E(delta T)) of 30 mK has been achieved