Water-soluble full-length single-wall carbon nanotube polyelectrolytes: Preparation and characterization

HiPco single-wall carbon nanotubes (SWNTs) have been noncovalently modified with ionic pyrene and naphthalene derivatives to prepare water-soluble SWNT polyelectrolytes (SWNT-PEs), which are analogous to polyanions and polycations. The modified nanotubes have been characterized with UV-vis-NIR, fluorescence, Raman and X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The nanotube-adsorbate interactions consist of π-π stacking interactions between the aromatic core of the adsorbate and the nanotube surface and specific contributions because of the substituents. The interaction between nanotubes and adsorbates also involves charge transfer from adsorbates to SWNTs, and with naphthalene sulfonates the role of a free amino group was important. The ionic surface charge density of the modified SWNTs is constant and probably controlled by electrostatic repulsion between like charges. The linear ionic charge density of the modified SWNTs is similar to that of common highly charged polyelectrolytes

Mechanisms Underlying Gas Exchange Alterations In An Experimental Model Of Pulmonary Embolism.

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 +/- 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 +/- 8.64 to 39.14 +/- 6.77 mmHg) and alveolar air (from 92.97 +/- 2.14 to 63.91 +/- 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 +/- 42.01 to 84.34 +/- 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 +/- 0.34 to 0.33 +/- 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 +/- 1.71 to 60.76 +/- 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 +/- 1.22 to 23.15 +/- 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 +/- 1.36 to 37.61 +/- 12.79 mmHg), as also did the calculated alveolar (from 56.38 +/- 22.47 to 178.09 +/- 37.46 mL) and physiological (from 0.37 +/- 0.05 to 0.75 +/- 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.391197-20

Polaron Effects on Superexchange Interaction: Isotope Shifts of TNT_N, TCT_C, and T∗T^* in Layered Copper Oxides

A compact expression has been obtained for the superexchange coupling of magnetic ions via intermediate anions with regard to polaron effects at both magnetic ions and intermediate anions. This expression is used to analyze the main features of the behavior of isotope shifts for temperatures of three types in layered cuprates: the Neel temperatures ($T_N$), critical temperatures of transitions to a superconducting state ($T_C$), and characteristic temperatures of the pseudogap in the normal state ($T^*$).Comment: 4 pages, 1 figur

Is the middle cerebral artery bifurcation aneurysm affected by morphological parameters of bifurcation?

Background: Aneurysm formation is a multifactorial process involving genetic, anatomical and environmental risk factors. A research focusing on the relationship between the presence of aneurysm and the morphology of the arteries will help in the pathogenesis and prediction of intracranial aneurysms. In this study, the relationship between the presence of aneurysm and various morphological parameters of aneurysm-related arteries was evaluated in patients with saccular middle cerebral artery (MCA) bifurcation aneurysm.Materials and methods: The archival images of 74 patients (62.2% women) were evaluated retrospectively. In this study, the angle between the ipsilateral MCA M1 segment and the dominant truncus (Φ1), the angle between the M1 segment and the recessive truncus (Φ2), and the bifurcation angle (Φ1 + Φ2) were compared. Bilateral internal carotid artery (ICA), MCA M1 segment, dominant and recessive truncus diameters and these diameters ratios were compared with the aneurysmal side and the contralateral side without aneurysm.Results: When the dominant truncus, recessive truncus angles and bifurcation angle were compared, a significant difference was found on the aneurysmal side (p < 0.0001). In the receiver operating characteristic analysis, when the bifurcation angle of 147.5° was accepted as the limit value, 78.4% sensitivity, 79.7% specificity, 79.5% positive predictive value and 78.7% negative predictive value were determined (area under the curve: 0.85).Conclusions: Our study of the morphological features of arteries associated with MCA bifurcation aneurysms showed that the presence of MCA aneurysms was significantly associated with large bifurcation angles

PAH/PCB CONCENTRATIONS IN MUSSELS (MYTILUS GALLOPROVINCIALIS) FROM IZMIT BAY

Abstract PAH and PCB concentrations were determined in mussel samples collected from Izmit Bay at the east of marmara Sea. The samples were taken from ten points in spring season and analyzed by gas chromatography after ultrasonic extraction. Total PAH concentrations varied between 2.5-13.9 ng.g-wet wt., while the total PCB concentrations were between 4.2-140.7 ng.g-wet wt. The results indicates a considerable pollution problem in the bay, especially with respect to PCBs

The interface of syntax with pragmatics and prosody in children with Autism Spectrum Disorders

In order to study problems of individuals with Autism Spectrum Disorders (ASD) with morphosyntax, we investigated twenty high-functioning Greek-speaking children (mean age:6;11) and twenty age- and language-matched typically developing children on environments that allow or forbid object clitics or their corresponding noun phrase. Children with ASD fell behind typically developing in comprehending and producing simple clitics and producing noun phrases in focus structures. The two groups performed similarly in comprehending and producing clitics in clitic left dislocation and in producing noun phrases in non-focus structures. We argue that children with ASD have difficulties at the interface of(morpho)syntax with pragmatics and prosody, namely, distinguishing a discourse prominent element, and considering intonation relevant for a particular interpretation that excludes clitics