Salt doping to improve thermoelectric power factor of organic nanocomposite thin films

Thermoelectric materials with a large Seebeck coefficient (S) and electrical conductivity (σ) are required to efficiently convert waste heat into electricity, but their interdependence makes simultaneously improving these variables immensely challenging. To address this problem, bilayers (BL) of poly(diallyldimethylammonium chloride) (PDDA) and double-walled carbon nanotubes (DWNT), stabilized by KBr-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) were deposited using layer-by-layer (LbL) assembly. Doping PEDOT:PSS with KBr, prior to DWNT dispersion and LbL assembly, results in a six-fold improvement in electrical conductivity with little change in the Seebeck coefficient. A maximum power factor (PF = S²σ) of 626 ± 39 μW m⁻¹ K⁻² is obtained from a 20 BL PDDA/PEDOT:PSS–DWNT film (∼46 nm thick), where PEDOT:PSS was doped with 3 mmol KBr. This large PF is due to the formation of a denser film containing a greater proportion of DWNT, which was influenced by the charge-screening effects imparted by the salt dopant that separates PSS from PEDOT. This study demonstrates a relatively simple strategy to significantly increase the thermoelectric performance of fully organic nanocomposites that are useful for low temperature thermoelectric devices.

Thermoelectric power factor of a polymer nanocomposite film, deposited using layer-by-layer assembly, was increased by doping with KBr.     

Epidemiological and clinical aspects of congenital heart disease in children in Tuzla Canton,Bosnia-Herzegovina

Congenital heart disease (CHD) is among the most frequent of all congenital anomalies. The purpose of this study was to present the results of an initial registration of children with CHD from January 1994 to December 1999 in Tuzla Canton, Bosnia-Herzegovina. The population studied consisted of all 39,699 live-born children in this area. Diagnosis of CHD was made by clinical findings, electrocardiography, chest X-ray, echocardiography, catheterisation or autopsy. In the 6-year period, 243 children were found to have CHD, i.e. a prevalence of 6.12 per 1000 live-born. Critical CHD was present in 58 of them, or 1.46 children per 1000 live-born. The average age at diagnosis was 1.47 years. There were 132 boys (54.3%) and 111 girls. The most frequent anomaly was ventricular septum defect with a prevalence of 2.49 per 1000 live-born, representing 40.7 % of the total anomalies. Of the total group, 46 (18.9%) had extracardiac anomalies related to syndromes. Cardiac surgery was indicated in 98 patients (40.3%) but could only be carried out in 42 (17.3%). A total of 63 (25.9%) patients died, 54 of whom within the 1st month of life. CONCLUSION: congenital heart disease is a very significant health problem in Tuzla Canton. It requires urgent measures in terms of organisation of early diagnosis and proper management.     

Induction of an Antigen-specific, CD1-restricted Cytotoxic T Lymphocyte Response In vivo

The majority of T cell responses are restricted to peptide antigens bound by polymorphic major histocompatibility complex (MHC) molecules. However, peptide antigens can be presented to T cells by murine non-MHC–encoded CD1d (mCD1) molecules, and human T cell lines specific for nonpeptide antigens presented on CD1 isoforms have been identified. It is shown here that antigen-specific, mCD1-restricted lymphocytes can be generated in vivo by immunizing mice with a combination of plasmids encoding chicken ovalbumin, murine CD1d, and costimulatory molecules. Splenocytes from immunized mice have CD1d-restricted, MHC- unrestricted, ovalbumin-specific cytolytic activity that can be inhibited by anti-CD1 antibodies as well as a competing CD1-binding peptide. These results suggest a physiologic role for murine CD1d to present exogenous protein antigens.     

Colocolic tumoral intussusception in the adult: value of multi-slice spiral CT imaging

Colocolic intussusception in the adult, caused by a tumoral process, is a rare clinical event.

We have studied two adults clinically presenting with a mass in the right iliac fossa, which was produced in one case by a carcinoma involving the right colon and in the other case involving the sigmoid.

Multi-slice spiral CT imaging showed the presence of a colocolic intussusception—the tumoral characteristics of the lesion eliminated the possibility of a lipoma—and it allowed a satisfactory presurgical evaluation of the pathological process.     

Disposition of perfluorinated acid isomers in Sprague-Dawley rats; part 1: single dose

Perfluorinated acids (PFAs) and their precursors (PFA-precursors) exist in the environment as linear and multiple branched isomers. These isomers are hypothesized to have different biological properties, but no isomer-specific data are currently available. The present study is the first in a two-part project examining PFA isomer-specific uptake, tissue distribution, and elimination in a rodent model. Seven male Sprague-Dawley rats were administered a single gavage dose of approximately 500 microg/kg body weight perfluorooctane sulfonate (C(8)F(17)SO(3)(-), PFOS), perfluorooctanoic acid (C(7)F(15)CO(2)H, PFOA), and perfluorononanoic acid (C(8)F(17)CO(2)H, PFNA) and 30 microg/kg body weight perfluorohexane sulfonate (C(6)F(13)SO(3)(-), PFHxS). Over the subsequent 38 d, urine, feces, and tail-vein blood samples were collected intermittently, while larger blood volumes and tissues were collected on days 3 and 38 for isomer analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). For all PFAs, branched isomers generally had lower blood depuration half-lives than the corresponding linear isomer. The most remarkable exception was for the PFOS isomer containing an alpha-perfluoromethyl branch (1m-PFOS), which was threefold more persistent than linear PFOS, possibly due to steric shielding of the hydrophilic sulfonate moiety. For perfluoromonomethyl-branched isomers of PFOS, a structure-property relationship was observed whereby branching toward the sulfonate end of the perfluoroalkyl chain resulted in increased half-lives. For PFHxS, PFOA, and PFOS, preferential elimination of branched isomers occurred primarily via urine, whereas for PFNA preferential elimination of the isopropyl isomer occurred via both urine and feces. Changes in the blood isomer profiles over time and their inverse correlation to isomer elimination patterns in urine, feces, or both provided unequivocal evidence of significant isomer-specific biological handling. Source assignment based on PFA isomer profiles in biota must therefore be conducted with caution, because isomer profiles are unlikely to be conserved in biological samples.     

‘Pseudopneumothorax’—Hold that chest tube!

We report a case of herniation of abdominal contents into the left hemithorax in a patient with a history of vague left-sided thoracoabdominal trauma 18 days previous to admission and who also had a recent 1-week history of upper respiratory symptoms, including cough, and then presented with dyspnoea and fever for 3 days. There was no preceding cardiorespiratory pathology of note. We also discuss the epidemiology, pathogenesis and management of blunt-traumatic diaphragmatic rupture.     

Human blood mononuclear cell in vitro cytokine response before and after two different strenuous exercise bouts in the presence of bloodroot and Echinacea extracts

The purpose of this multidisciplinary investigation was to characterize cytokine production by human blood mononuclear cells after 2 contrasting exercise bouts (a maximal graded oxygen consumption [VO₂max] test and 90 min of cycling at 85% of ventilatory threshold [VT]) when stimulated in vitro with extracts from bloodroot (Sanguinaria canadensis), coneflower (Echinacea tennesseensis), or solvent vehicle controls. Blood was sampled pre- and post-exercise. Production of TNF, IL-1β, and IL-10 were measured at 24, 48, and 72 h, respectively. In the VO₂max test there was a main effect of exercise such that exercise increased cytokine synthesis and a main effect of stimulant such that bloodroot extracts significantly increased cytokine production compared to other stimulants or controls. In the 90-min bout, there was a main effect of exercise for TNF and IL-1β (but not IL-10) such that exercise decreased cytokine synthesis and a main effect of stimulant such that bloodroot extracts significantly increased cytokine production compared to other stimulants or controls, with exercise × stimulant interactions for both IL-1β and IL-10. A similar though weaker effect was seen with Echinacea extracts; subsequent biochemical analyses suggested this was related to alkamide decay during 3 years undisturbed storage at ultralow (− 80 °C) temperature. In this study, the VO₂max test was associated with enhanced cytokine production whereas the 90-min cycling at 85% VT was associated with suppressed cytokine production. Bloodroot extracts were able to increase cytokine production in both contexts. Herbal extracts purported to offset exercise-associated effects on immune activity warrant continued investigation.