Search results for "Pulse"

Identification of Manganese(IV) Centers in Archaeological Glass Using Microsample Coatings Attached to PolymerFilm Electrodes

2001

Identification of MnO2 nodulae in archaeological glass by linear scan and differential pulse voltammetry using abrasive-conditioned microsamples attached to polymer film (Elvacite 2044) electrodes is described. Voltammetric responses for manganese-containing samples parallels to those obtained for β- and γ-MnO2 upon immersion of modified electrodes into NaCl, KCl and acetic/acetate aqueous media. The observed electrochemical response provides information on the open microporous structure of the MnO2 forms and the conditions of their formation during the weathering process of buried glass.

Near Isotropic D4d Spin Qubits as Nodes of a Gd(III)-Based Metal-Organic Framework

2021

Embedding coherent spin motifs in reproducible molecular building blocks is a promising pathway for the realization of quantum technologies. Three-dimensional (3D) MOFs are a versatile platform for the rational design of extended structures employing coordination chemistry. Here, we report the synthesis and characterization of a gadolinium(III)-based MOF, [Gd(bipyNO)4](TfO)3·xMeOH (bipyNO = bipyridine,N,N′-dioxide; TfO = triflate; and MeOH = methanol) (quMOF-1), which presents a unique coordination geometry that leads to a tiny magnetic anisotropy (in terms of D, an equivalent zero-field splitting would be achieved by D = 0.006 cm–1) even compared with regular Gd(III) complexes. Pulsed elec…

NMR spectral assignment of substituted salicylaldoximes by inverse pulse techniques withz-gradient selection: correlation of NMR parameters with subs…

1997

Synthesis, characterization and crystal structure of 2-dicyanomethylene-1,3-bis(ferrocenylmethyl)-1,3-diazolidine

1993

By reaction of N,N′-ethylenebis(ferrocenylmethylamine)1 with tetracyanoethylene in dichloromethane the yellow compound 2-dicyanomethylene-1,3-bis(ferrocenylmethyl)-1,3-diazolidine 2 can be isolated. The single-crystal structure of 2 has been determined. It crystallizes in the non-centrosymmetric trigonal space group P3221, a= 12.255(2), c= 13.831(7)A, Z= 3. Refinement of the atomic parameters by least-squares techniques gave a final R factor of 0.038 (R′= 0.034) for 1782 observed reflections having I > 2.5δ(I). Anomalous values of the bond distances and the vinyl carbon chemical shift in the 13C NMR spectrum of 2 are explained on the basis of a polarization due to a combination of the elect…

Relationship of choroidal thickness with pulsatile hemodynamics in essential hypertensive patients

2021

Controversy exists about the association of choroidal thickness (CTh) with blood pressure (BP) values. There is some evidence suggesting that central hemodynamics changes are associated with microvascular disease. Our study was aimed to assess the relationships between CTh and clinic and 24-h BP and between CTh and estimated 24-h aortic pulse pressure (aPP), 24-h aortic systolic BP (aSBP), and 24-h aortic augmentation index (aAIx) in a group of hypertensive patients. We enrolled 158 hypertensive subjects (mean age 48 ± 13 years) all of which underwent evaluation of the choroidal district by Swept-Source optical coherence tomography (SS-OCT) and 24-h BP monitoring, in order to measure periph…

ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE

2007

This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule…

Photoplethysmography Analysis of Artery Properties in Patients with Cardiovascular Diseases

2008

In this study arterial parameters of healthy subjects were compared to those of patients with cardiovascular diseases. The photoplethysmography (PPG) measurements of blood volume pulsations have been performed. Using a novel algorithm for analysis of simultaneously measured ear and finger PPG signals, arterial parameters were evaluated in representative groups of healthy subjects and patients with cardiovascular diseases. Digital volume pulse (DVP), pulse cycle duration (T), augmentation index (AIx), reflection index (RI) and transit time of reflected wave (RTT) were evaluated in every heartbeat cycle. Correlations between the AIx and RI, T and RTT, AIx and standard deviation of AIx, RTT an…

The Spike Noise Based on the Renewal Point Process and Its Possible Applications

2010

We consider a non-Markovian random process in the form of spikes train, where the time intervals between neighboring delta-pulses are mutually independent and identically distributed, i.e. represent the renewal process (1967). This noise can be interpreted as the derivative of well-known continuous time random walk (CTRW) model process with fixed value of jumps. The closed set of equations for the characteristic functional of the noise, useful to split the correlations between stochastic functionals (2008), is obtained. In the particular case of Poisson statistics these equations can be exactly solved and the expression for the characteristic functional coincides with the result for shot no…

Digital pulse processing techniques for X-ray and gamma ray semiconductor detectors

2012

Digital pulse processing (DPP) systems, based on direct digitizing and processing of detector signals, have recently been favoured over analog electronics, ensuring higher flexibility, stability and lower dead time. We present our research activities on the development of X-ray and gamma ray spectrometers based on semiconductor detectors and DPP systems. We developed off-line and real-time DPP systems able to perform precise height and shape analysis of detector pulses. X-ray and gamma ray spectra measurements with cadmium telluride (CdTe) and germanium (Ge) detectors highlight the excellent performance of the systems both at low and high rate environments (up to 800 kcps).

Un sistema digitale innovativo per la caratterizzazione energia-flusso di fasci X diagnostici

2016

La conoscenza della distribuzione energetica e del rateo di fluenza dei fasci X è essenziale nei controlli di qualità in medicina diagnostica, sia in termini dosimetrici che della qualità delle immagini. Gli spettri energetici possono essere utilizzati per stime accurate delle tensioni dei tubi (kVp), per la correzione di distorsioni dovute al beam-hardening e per la corretta implementazione delle nuove tecniche dual-energy [1]. In mammografia, gli spettri energetici possono essere usati per stimare l’esposizione, il kerma in aria e la distribuzione energetica della dose assorbita nei tessuti, superando gli inconvenienti dovuti alla dipendenza energetica della risposta dei dosimetri (a stat…