Respiratory Properties of Blood and Responses to Diving of the Platypus, Prnithorhynchus Anatinus (Shaw)*

1. The O2-Hb dissociation curve for platypus blood shows a typical sigmoid shape with a pronounced Bohr effect. 2. The O2 capacity for one specimen was 23.5 vol % with a corresponding hematocrit of 50 per cent. 3. The blood displayed a considerable Haldane effect and a large difference in buffer capacity between reduced and oxygenated blood. 4. Arterial blood samples taken during experimental submersion were analyzed for O2 and CO2 pressure and content. CaO2 falls rapidly during diving and reaches a low of 2 vol % after approximately 3 min, which was close to the endurance limit during experimental conditions. A quick restoration of arterial O2 saturation characterized the recovery. 5. Platypus showed a distinct bradycardia upon submersion. The rate of decline in heart rate was more pronounced if the arterial blood pressure - increased in response to submersion. 6. The findings are discussed in relation to the normal diving habits of the platypus

Respiratory Properties of Blood and Pattern of Gas Exchange in the Lungfish Neoceratodus forsteri (Krefft)

Blood respiratory properties and gas exchange patterns have been studied in the lungfish Neoceratodus. O2 - Hb dissociation curve reveals a high affinity for O2 (P50 of 11 mm Hg at PCO2 3.5 mm Hg). No Root effect but a pronounced Bohr effect was discernible. Temperature exerted only a minor influence on the affinity for O2. The CO2 dissociation curves conform to the shape observed in other classes of vertebrates and show a steep initial portion. The buffering capacity of the blood was low being 13.3 mMol/1/pH. An increased buffering power upon reduction of Hb was apparent. During rest in well oxygenated water, gill breathing prevailed entirely. Pulmonary arterial blood assumed to represent mixed arterial blood characteristically showed a Pco2 averaging 3.5 mm Hg. PaO2 was 40 mm Hg corresponding to an O2 saturation of 95%. The pulmonary venous blood showed gas partial pressures in equilibrium with those in pulmonary arterial blood and air, documenting the minor importance of the lung as a gas exchanger during these conditions. When the fish was artificially exposed to air PaO2 diminished to 10-15 mm Hg with a concurrent increase in PaCO2 to 20 mm Hg in 30 min. While the lung performed well as an O2 absorber during air exposure it was totally inefficient in eliminating CO2. The data indicate that Neoceratodus is unfit to live out of water for any length of time

Pavlov's dog associative learning demonstrated on synaptic-like organic transistors

In this letter, we present an original demonstration of an associative learning neural network inspired by the famous Pavlov's dogs experiment. A single nanoparticle organic memory field effect transistor (NOMFET) is used to implement each synapse. We show how the physical properties of this dynamic memristive device can be used to perform low power write operations for the learning and implement short-term association using temporal coding and spike timing dependent plasticity based learning. An electronic circuit was built to validate the proposed learning scheme with packaged devices, with good reproducibility despite the complex synaptic-like dynamic of the NOMFET in pulse regime

Interface Dipole : Effects on Threshold Voltage and Mobility for both Amorphous and Poly-crystalline Organic Field Effect Transistors

We report a detailed comparison on the role of a self-assembled monolayer (SAM) of dipolar molecules on the threshold voltage and charge carrier mobility of organic field-effect transistor (OFET) made of both amorphous and polycrystalline organic semiconductors. We show that the same relationship between the threshold voltage and the dipole-induced charges in the SAM holds when both types of devices are fabricated on strictly identical base substrates. Charge carrier mobilities, almost constant for amorphous OFET, are not affected by the dipole in the SAMs, while for polycrystalline OFET (pentacene) the large variation of charge carrier mobilities is related to change in the organic film structure (mostly grain size).Comment: Full paper and supporting informatio

Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi level pinning at the molecule-metal interface

We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices and we examine to what extent the nature of the pi end-group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. For all the pi-groups investigated here, we observe rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (S. Lenfant et al., Nano Letters 3, 741 (2003)).The experimental current-voltage curves are analyzed with a simple analytical model, from which we extract the energy position of the molecular orbital of the pi-group in resonance with the Fermi energy of the electrodes. We report the experimental studies of the band lineup in these silicon/alkyl-pi conjugated molecule/metal junctions. We conclude that Fermi level pinning at the pi-group/metal interface is mainly responsible for the observed absence of dependence of the rectification effect on the nature of the pi-groups, even though they were chosen to have significant variations in their electronic molecular orbitalsComment: To be published in J. Phys. Chem.

Respiratory Control in the Lungfish, Neoceratodus Forsteri (Krefft)

1. Respiratory control has been studied in the lungfish, Neoceratodus forsteri by measuring ventilation (Ve), oxygen uptake (VO2), per cent O2 extraction from water, breathing rates of branchial and aerial respiration and changes in blood gas and pulmonary gas composition during exposure to hypoxia and hypercarbia. 2. Hypoxic water represents a strong stimulus for compensatory increase in both branchial and aerial respiration. Water ventilation increases by a factor of 3 or 4 primarily as a result of increased depth of breathing. 3. The ventilation perfusion ratio decreased during hypoxia because of a marked increase in cardiac output. Hypoxia also increased the fraction of total blood flow perfusing the lung. Injection of nitrogen into the lung evoked no compensatory changes. 4. It is concluded that the chemoreceptors eliciting the compensatory changes are located on the external side facing the ambient water or in the efferent branchial blood vessels. 5. Elevated pCO2 in the ambient water depressed the branchial respiration but stimulated aerial respiration. 6. It is suggested that the primary regulatory effect of the response to increased ambient pCO2 is to prevent CO2 from entering the animal, while the secondary stimulation of air breathing is caused by hypoxic stimulation of chemoreceptors located in the efferent branchial vessels

Definition of Metabolic Syndrome: Report of the National Heart, Lunch, and Blood Institute/American Heart Association Conference on Scientific Issues Related to Definition

https://www.ahajournals.org/doi/pdf/10.1161/01.atv.0000111245.75752.c

Current rectification by simple molecular quantum dots: an ab-initio study

We calculate a current rectification by molecules containing a conjugated molecular group sandwiched between two saturated (insulating) molecular groups of different length (molecular quantum dot) using an ab-initio non-equilibrium Green's function method. In particular, we study S-(CH2)m-C10H6-(CH2)n-S dithiol with Naphthalene as a conjugated central group. The rectification current ratio ~35 has been observed at m = 2 and n = 10, due to resonant tunneling through the molecular orbital (MO) closest to the electrode Fermi level (lowest unoccupied MO in the present case). The rectification is limited by interference of other conducting orbitals, but can be improved by e.g. adding an electron withdrawing group to the naphthalene.Comment: 8 pages, 9 figure