Evaluation of volume of the sphenoid sinus according to sex,facial type,skeletal class,and presence of a septum: a cone-beam computed tomographic study

We have used cone-beam computed tomographic (CT) images to retrospectivelyevaluate the influence of sex, skeletal class, facial type, and the presence of septa on the volume of the sphenoid sinus in 172 images from 85 men (mean (SD) age 28 (2) years) and 87 women (mean (SD) age 30 (1) years). Skeletal class and facial type were calculated for each patient from multiplanar reconstructions using NemoCeph® software. Volumetric analysis of the sphenoid sinus was made with the help of the ITK-SNAP® 3.4.0 segmentation software, while the presence or absence of septa in the sphenoid sinus was evaluated with the Carestream 3D Imaging® software 3.4.3. We analysed the results using two-way ANOVA, Student’s independent sample t test, and Fisher’s exact test, as appropriate, and probabilities of <0.05 were accepted as significant. Sex (p = 0.0946), facial type (p = 0.790), and skeletal class (p = 0.120) had no significant influence on the volume of the sphenoid sinus, and nor did the volumes of the right and left sphenoid sinuses (p = 0.0923), or the presence of a septum within the sinus (p = 0.330) in its volume.     

Neural selectivity,efficiency, and dose equivalence in deep brain stimulation through pulse width tuning and segmented electrodes

BackgroundAchieving deep brain stimulation (DBS) dose equivalence is challenging, especially with pulse width tuning and directional contacts. Further, the precise effects of pulse width tuning are unknown, and recent reports of the effects of pulse width tuning on neural selectivity are at odds with classic biophysical studies.MethodsWe created multicompartment neuron models for two axon diameters and used finite element modeling to determine extracellular influence from standard and segmented electrodes. We analyzed axon activation profiles and calculated volumes of tissue activated.ResultsWe find that long pulse widths focus the stimulation effect on small, nearby fibers, suppressing distant white matter tract activation (responsible for some DBS side effects) and improving battery utilization when equivalent activation is maintained for small axons. Directional leads enable similar benefits to a greater degree. Reexamining previous reports of short pulse stimulation reducing side effects, we explore a possible alternate explanation: non-dose equivalent stimulation may have resulted in reduced spread of neural activation. Finally, using internal capsule avoidance as an example in the context of subthalamic stimulation, we present a patient-specific model to show how long pulse widths could help increase the biophysical therapeutic window.DiscussionWe find agreement with classic studies and predict that long pulse widths may focus the stimulation effect on small, nearby fibers and improve power consumption. While future pre-clinical and clinical work is necessary regarding pulse width tuning, it is clear that future studies must ensure dose equivalence, noting that energy- and charge-equivalent amplitudes do not result in equivalent spread of neural activation when changing pulse width.     

Enhanced electrochemical and electrocatalytic activity of a new supramolecular manganese-porphyrin species containing four bis(bipyridine)(aqua)ruthenium(II) complexes

A novel supramolecular species [MnTPyP{Ru(bipy)₂H₂O}₄](PF₆)₉ containing four cis-bis(bipyridine)(aqua)ruthenium(II) complexes attached to the peripheral pyridyl groups of meso-tetra(4-pyridyl)porphyrin manganese(III) (MnTPyP) has been synthesized, and employed as the precursor of a rather promising multinuclear oxo-transfer catalyst. This complex forms molecular films by dip coating. Such films are soluble in water, but can be stabilized by exchanging the PF^?₆ anions by [Fe(CN)₆]^4? or [Zn–TPPS]^4?. They exhibit remarkable electrochemical and electrocatalytic activity, as demonstrated in the oxidation of nitrite ions. In this case, experimental evidence supports the involvement of electrochemically generated [ORu^IV]²⁺ groups in the oxidation reaction, reflecting the characteristic reactivity of high-valence metal–oxo complexes.     

Electrochemical behaviour of 2-(4′-hydroxybenzeneazo)benzoic-acid at pyrolytic graphite electrodes

The electrochemical reduction of 2-(4′-hydroxybenzeneazo)benzoic acid (I) has been studied at pyrolytic graphite electrodes in the pH range 2.0–10.4. The cyclic voltammetric behaviour clearly indicated an ECE mechanism in acidic medium in which the two-electron two-proton reduction of I gives the hydrazo derivative. The acid catalysed disproportionation of the hydrazo intermediate was also studied in the pH range 2.0–6.0 and the value of k′/[H⁺] was found to be 1.4 × 10^?2 1 mol^?1 s^?1 The products of the reduction have been isolated and characterized using IR, melting point, mass and related techniques.     

Impedance of rough capacitive electrodes: the role of surface disorder

The interfacial impedance of solid electrodes in the absence of Faradaic reactions usually deviates from purely capacitive behaviour; this effect is enhanced on rough electrodes. We present a qualitative experiment showing that capacitance dispersion on solid electrodes is due to surface disorder (i.e. heterogeneities on the atomic scale) rather than roughness (i.e. geometric irregularities much larger than those on the atomic scale).     

Methanol oxidation at platinum electrodes in alkaline solution: comparison between supported catalysts and model systems

Methanol oxidation was studied in 0.1 M NaOH at supported Pt electrodes, and compared with the single crystal Pt electrodes, Pt(1 1 1), Pt(1 1 0) and Pt(3 3 2), chosen as model systems, and with a polycrystalline Pt electrode. The supported Pt electrodes were obtained by chemical (Pt–C/GC) and electrochemical (Pt/GC) deposition of the catalyst layer on glassy carbon resulting in the same metal loading of 20 μg_Pt cm^?2. Using STM in air, the average particle size distributions, 3–6 nm at Pt–C/GC and 4–32 nm at Pt/GC were determined. Both supported Pt catalysts were less active than polycrystalline Pt. Negligible differences in the kinetics observed between Pt–C/GC and Pt(1 1 0) and also Pt/GC and Pt(1 1 1) suggested that the activities of supported Pt electrodes could be correlated with the activities of single crystal Pt electrodes oriented as the sites dominating in the Pt particles in catalyst deposits. The electrocatalytic activities of the electrodes studied increase in the sequence: Pt(3 3 2) > polycrystalline Pt > Pt–C/GC ～ Pt(1 1 0) > Pt/GC ～ Pt(1 1 1). On the basis of diagnostic criteria obtained, the chemical reaction between HCO_ad and OH_ad giving formate was proposed as the rate limiting step in methanol oxidation.     

Adsorption of organic compounds and hydrophilicity of bismuth,cadmium and antimony electrodes

The adsorption behavior of various organic compounds at bismuth, antimony, cadmium, mercury and other “mercury-like” metals has been discussed. The systematic trends of the influence of the chemical nature of electrode metal and adsorbate to the molecular interaction parameter, a; limiting Gibbs adsorption, Γ_{A, max}; and Gibbs energy of adsorption, ΔG_A⁰, have been analyzed. The ingredients of the total Gibbs energy of organic compounds adsorption have been found. A new more general method for obtaining the metal-water; interaction Gibbs energy has been worked out and used. It was found that the dependence of Gibbs energy of metal-water interaction on the chemical nature of metal and aliphatic organic compound studied is weak. Only in the case of chemically very different metals, for example for Sb and Zn, the difference of Gibbs energy of metal-water interaction values is somewhat higher than the exactness of the determination of the experimental values of Gibbs energy of organic compound adsorption.