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1.
J Chem Phys ; 151(18): 184305, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31731862

RESUMO

Using electron spectroscopy, we investigated the nanoplasma formation process generated in xenon clusters by intense soft x-ray free electron laser (FEL) pulses. We found clear FEL intensity dependence of electron spectra. Multistep ionization and subsequent ionization frustration features are evident for the low FEL-intensity region, and the thermal electron emission emerges at the high FEL intensity. The present FEL intensity dependence of the electron spectra is well addressed by the frustration parameter introduced by Arbeiter and Fennel [New J. Phys. 13, 053022 (2011)].

2.
Eur Arch Otorhinolaryngol ; 276(12): 3281-3286, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31520164

RESUMO

OBJECTIVE: Electroneurography (ENoG) reliably predicts the prognosis of facial palsy. However, the results of ENoG are dependent on the location, where the wave is detected, as a compound muscle action potential (CMAP) arising from the facial muscles. To minimize errors in prognostic prediction, we analysed the latencies of facial CMAPs. MATERIALS AND METHODS: Fifty-seven patients with unilateral peripheral facial palsy and 24 healthy volunteers were enrolled. Amplitudes, negative peak latencies (NPL), and rise latencies (RL) of CMAPs were measured on the paralysed and healthy sides in patients and in healthy volunteers. The relationships of these latencies with ENoG values and the lowest House-Brackmann (H-B) scores were also analysed. RESULTS: The amplitude of CMAP on the paralysed side was smaller, and NPL and RL were longer, than those on the healthy side in patients and healthy volunteers (p < 0.01). In patients, there was no difference in NPL between the ENoG < 40% group and the ENoG ≥ 40% group. Conversely, there was a significant difference in RL between the ENoG < 40% group and ENoG ≥ 40% group (p = 0.03). No relationships were observed between NPL or RL and the lowest H-B score. CONCLUSIONS: NPL and RL of CMAP on the paralysed side were equivalent or longer than those on the healthy side. During ENoG for facial palsy, CMAP should be measured on the healthy side first, and then detected (and the amplitude measured) on the paralysed side with reference to CMAP latency on the healthy side, to reduce errors in detecting facial CMAPs.

3.
J Chem Phys ; 151(10): 104308, 2019 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-31521092

RESUMO

We have investigated the ionization and fragmentation of a metallo-endohedral fullerene, Sc3N@C80, using ultrashort (10 fs) x-ray pulses. Following selective ionization of a Sc (1s) electron (hν = 4.55 keV), an Auger cascade leads predominantly to either a vibrationally cold multiply charged parent molecule or multifragmentation of the carbon cage following a phase transition. In contrast to previous studies, no intermediate regime of C2 evaporation from the carbon cage is observed. A time-delayed, hard x-ray pulse (hν = 5.0 keV) was used to attempt to probe the electron transfer dynamics between the encapsulated Sc species and the carbon cage. A small but significant change in the intensity of Sc-containing fragment ions and coincidence counts for a delay of 100 fs compared to 0 fs, as well as an increase in the yield of small carbon fragment ions, may be indicative of incomplete charge transfer from the carbon cage on the sub-100 fs time scale.

4.
Phys Chem Chem Phys ; 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31436275

RESUMO

Momenta of ions from diiodomethane molecules after multiple ionization by soft-X-ray free-electron-laser pulses are measured. Correlations between the ion momenta are extracted by covariance methods formulated for the use in multiparticle momentum-resolved ion time-of-flight spectroscopy. Femtosecond dynamics of the dissociating multiply charged diiodomethane cations is discussed and interpreted by using simulations based on a classical Coulomb explosion model including charge evolution.

5.
Acta Otolaryngol ; 139(9): 823-827, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31268392

RESUMO

Background: The degree of distress caused by the sequelae of peripheral facial nerve palsy usually depends on the severity of synkinesis. Objective: To clarify whether electroneurography (ENoG) can predict the severity of synkinesis after peripheral facial nerve palsy. Materials and methods: One-hundred and fourteen patients treated for facial nerve palsy at our hospital from April 2014-September 2016 were retrospectively reviewed. ENoG was performed 10-16 days after symptom onset. Patients were classified into Groups A (ENoG value 10%-20%, n = 9) and B (ENoG value <10%, n = 21). Eight months after symptom onset, electrophysiological and symptomatic outcomes were evaluated as the aberrant regeneration ratio of the blink reflex and the total synkinesis score of the Sunnybrook facial grading system, respectively. The outcomes of the groups were compared. Results: Group B had a significantly higher median aberrant regeneration ratio (0% versus 87%, p=.015), median total synkinesis score (1 versus 3, p < .001), and incidence of moderate-to-severe synkinesis (0% versus 57.2%, p=.003) than did Group A. Conclusions and significance: Patients with an ENoG value of <10% have higher risks of aberrant regeneration and moderate-to-severe synkinesis than those with an ENoG value of 10%-20%. Patients with ENoG values of <10% may require rehabilitation to prevent synkinesis.


Assuntos
Paralisia de Bell/diagnóstico por imagem , Eletrodiagnóstico/métodos , Paralisia Facial/diagnóstico por imagem , Herpes Zoster da Orelha Externa/diagnóstico por imagem , Sincinesia/diagnóstico por imagem , Sincinesia/etiologia , Adulto , Paralisia de Bell/complicações , Estudos de Coortes , Expressão Facial , Paralisia Facial/terapia , Feminino , Herpes Zoster da Orelha Externa/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Regeneração Nervosa/fisiologia , Neurofisiologia/métodos , Recuperação de Função Fisiológica , Estudos Retrospectivos , Medição de Risco , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Estatísticas não Paramétricas
6.
Nat Commun ; 10(1): 2186, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-31097703

RESUMO

The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in real-time. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (∼20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (∼100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation.

7.
Phys Rev Lett ; 120(22): 223201, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29906148

RESUMO

We show that electron and ion spectroscopy reveals the details of the oligomer formation in Ar clusters exposed to an x-ray free electron laser (XFEL) pulse, i.e., chemical dynamics triggered by x rays. With guidance from a dedicated molecular dynamics simulation tool, we find that van der Waals bonding, the oligomer formation mechanism, and charge transfer among the cluster constituents significantly affect ionization dynamics induced by an XFEL pulse of moderate fluence. Our results clearly demonstrate that XFEL pulses can be used not only to "damage and destroy" molecular assemblies but also to modify and transform their molecular structure. The accuracy of the predictions obtained makes it possible to apply the cluster spectroscopy, in connection with the respective simulations, for estimation of the XFEL pulse fluence in the fluence regime below single-atom multiple-photon absorption, which is hardly accessible with other diagnostic tools.

8.
Phys Chem Chem Phys ; 19(30): 19707-19721, 2017 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-28530728

RESUMO

Coulomb explosion of diiodomethane CH2I2 molecules irradiated by ultrashort and intense X-ray pulses from SACLA, the Japanese X-ray free electron laser facility, was investigated by multi-ion coincidence measurements and self-consistent charge density-functional-based tight-binding (SCC-DFTB) simulations. The diiodomethane molecule, containing two heavy-atom X-ray absorbing sites, exhibits a rather different charge generation and nuclear motion dynamics compared to iodomethane CH3I with only a single heavy atom, as studied earlier. We focus on charge creation and distribution in CH2I2 in comparison to CH3I. The release of kinetic energy into atomic ion fragments is also studied by comparing SCC-DFTB simulations with the experiment. Compared to earlier simulations, several key enhancements are made, such as the introduction of a bond axis recoil model, where vibrational energy generated during charge creation processes induces only bond stretching or shrinking. We also propose an analytical Coulomb energy partition model to extract the essential mechanism of Coulomb explosion of molecules from the computed and the experimentally measured kinetic energies of fragment atomic ions by partitioning each pair Coulomb interaction energy into two ions of the pair under the constraint of momentum conservation. Effective internuclear distances assigned to individual fragment ions at the critical moment of the Coulomb explosion are then estimated from the average kinetic energies of the ions. We demonstrate, with good agreement between the experiment and the SCC-DFTB simulation, how the more heavily charged iodine fragments and their interplay define the characteristic features of the Coulomb explosion of CH2I2. The present study also confirms earlier findings concerning the magnitude of bond elongation in the ultrashort X-ray pulse duration, showing that structural damage to all but C-H bonds does not develop to a noticeable degree in the pulse length of ∼10 fs.

9.
Auris Nasus Larynx ; 44(5): 602-606, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28119092

RESUMO

OBJECTIVE: Marginal mandibular nerve paralysis is the most frequent complication of benign parotid tumor surgery and results in cosmetic deformity. The purpose of this study was to develop a new electroneurography method for marginal mandibular nerve paralysis using electroneurography (ENoG) and judge its usefulness for clinical practice. METHODS: Twenty-seven patients who underwent surgery for benign parotid tumor were enrolled. We proposed and use the mandibular angle method, in which the recording electrode was placed on the skin above the depressor anguli oris muscle while the reference electrode was placed on the skin of the parietal region, and percutaneous electrical stimulation was applied to enclose the mandibular angle that could measure the function of the marginal mandibular nerve solely. Preoperative and postoperative ENoG values were compared in paralytic and non-paralytic patients. RESULTS: The mean postoperative ENoG value (35.0%) was lower than the preoperative value (90.5%) in paralytic patients, whereas no difference was observed between preoperative (79.3%) and postoperative (69.5%) ENoG values in non-paralytic patients. CONCLUSION: A new ENoG method (mandibular angle method) was thought to reflect marginal mandibular nerve injury and might be useful for determining the likelihood of paralysis.


Assuntos
Estimulação Elétrica , Paralisia Facial/diagnóstico , Neoplasias Parotídeas/cirurgia , Complicações Pós-Operatórias/diagnóstico , Traumatismos do Nervo Trigêmeo/diagnóstico , Adulto , Idoso , Paralisia Facial/etiologia , Feminino , Humanos , Nervo Mandibular , Pessoa de Meia-Idade , Glândula Parótida/cirurgia , Prognóstico , Traumatismos do Nervo Trigêmeo/complicações
10.
Sci Rep ; 5: 15088, 2015 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26462615

RESUMO

We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs' surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials.

11.
J Phys Chem Lett ; 6(15): 2944-9, 2015 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-26267186

RESUMO

In recent years, free-electron lasers operating in the true X-ray regime have opened up access to the femtosecond-scale dynamics induced by deep inner-shell ionization. We have investigated charge creation and transfer dynamics in the context of molecular Coulomb explosion of a single molecule, exposed to sequential deep inner-shell ionization within an ultrashort (10 fs) X-ray pulse. The target molecule was CH3I, methane sensitized to X-rays by halogenization with a heavy element, iodine. Time-of-flight ion spectroscopy and coincident ion analysis was employed to investigate, via the properties of the atomic fragments, single-molecule charge states of up to +22. Experimental findings have been compared with a parametric model of simultaneous Coulomb explosion and charge transfer in the molecule. The study demonstrates that including realistic charge dynamics is imperative when molecular Coulomb explosion experiments using short-pulse facilities are performed.

12.
Acta Crystallogr D Biol Crystallogr ; 69(Pt 5): 838-42, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23633593

RESUMO

X-ray free-electron lasers (FELs) enable crystallographic data collection using extremely bright femtosecond pulses from microscopic crystals beyond the limitations of conventional radiation damage. This diffraction-before-destruction approach requires a new crystal for each FEL shot and, since the crystals cannot be rotated during the X-ray pulse, data collection requires averaging over many different crystals and a Monte Carlo integration of the diffraction intensities, making the accurate determination of structure factors challenging. To investigate whether sufficient accuracy can be attained for the measurement of anomalous signal, a large data set was collected from lysozyme microcrystals at the newly established `multi-purpose spectroscopy/imaging instrument' of the SPring-8 Ångstrom Compact Free-Electron Laser (SACLA) at RIKEN Harima. Anomalous difference density maps calculated from these data demonstrate that serial femtosecond crystallography using a free-electron laser is sufficiently accurate to measure even the very weak anomalous signal of naturally occurring S atoms in a protein at a photon energy of 7.3 keV.


Assuntos
Cristalografia por Raios X/métodos , Lasers , Conformação Proteica , Enxofre/química , Cristalografia por Raios X/instrumentação , Cisteína/química , Modelos Moleculares , Muramidase/química
13.
Acta Otolaryngol ; 133(3): 327-33, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23163890

RESUMO

CONCLUSION: The midline electroneurography (ENoG) method might reflect total facial nerve degeneration. OBJECTIVE: We compared ENoG values in patients with facial palsy using two different methods, the midline method and five electroneurogram recordings, to reveal whether the ENoG value obtained with the midline method reflects total facial nerve degeneration. METHODS: Forty patients with facial palsy were enrolled. Compound muscle action potentials (CMAPs) were recorded using the midline method, in which the anode was placed on the mental protuberance and the cathode was placed on the philtrum. Additionally, five electroneurogram recordings were obtained by placing the anode on the skin of the parietal region and five cathodes on the skin over five facial muscles (frontalis, orbicularis oculi, nasalis, orbicularis oris, and depressor anguli oris muscles). ENoG values recorded using the two methods were compared. RESULTS: The ENoG values of the five facial muscles did not differ from those obtained using the midline method. The total ENoG value calculated by summing five CMAPs from five facial muscles, which is considered to reflect total facial nerve degeneration, was not significantly different from that using midline methods; moreover, a strong positive correlation coefficient (r = 0.87) was found between them.


Assuntos
Paralisia de Bell/diagnóstico , Paralisia de Bell/fisiopatologia , Eletrodiagnóstico/métodos , Herpes Zoster da Orelha Externa/fisiopatologia , Degeneração Neural/diagnóstico , Degeneração Neural/fisiopatologia , Potenciais de Ação/fisiologia , Adulto , Anti-Inflamatórios/uso terapêutico , Antivirais/uso terapêutico , Paralisia de Bell/tratamento farmacológico , Quimioterapia Combinada , Estimulação Elétrica/métodos , Músculos Faciais/inervação , Nervo Facial/efeitos dos fármacos , Nervo Facial/fisiopatologia , Feminino , Herpes Zoster da Orelha Externa/diagnóstico , Herpes Zoster da Orelha Externa/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Degeneração Neural/tratamento farmacológico , Valor Preditivo dos Testes , Prednisolona/uso terapêutico , Prognóstico
15.
Phys Rev Lett ; 108(23): 233401, 2012 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-23003953

RESUMO

All matter exposed to intense femtosecond x-ray pulses from the Linac Coherent Light Source free-electron laser is strongly ionized on time scales competing with the inner-shell vacancy lifetimes. We show that for nanoscale objects the environment, i.e., nanoparticle size, is an important parameter for the time-dependent ionization dynamics. The Auger lifetimes of large Ar clusters are found to be increased compared to small clusters and isolated atoms, due to delocalization of the valence electrons in the x-ray-induced nanoplasma. As a consequence, large nanometer-sized samples absorb intense femtosecond x-ray pulses less efficiently than small ones.

16.
Proc Natl Acad Sci U S A ; 108(41): 16912-5, 2011 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-21969540

RESUMO

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes.

17.
Acta Otolaryngol ; 130(4): 520-4, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19688619

RESUMO

CONCLUSION: The novel midline electroneurography (ENoG) method may have advantages over the standard method in terms of ease of electrode setting, and the ENoG value may be a useful prognostic factor. OBJECTIVE: We compared ENoG performed in patients with facial palsy using two different methods--the new midline method and standard method--in terms of the amplitudes of the compound muscle action potentials(CMAPs) and relationship between the ENoG value and clinical course. METHODS: A total of 64 patients with facial palsy were enrolled. CMAPs were recorded using the midline method, in which the recording electrodes were placed on the mental protuberance and philtrum over the orbicularis oris muscle, and the standard method, in which the recording electrodes were set close to the nasolabial fold. Percutaneous electrical stimulation was applied to the main trunk of the facial nerve.The amplitudes of the CMAPs and the relationship between the ENoG value and the period to full recovery from the facial palsy were compared. RESULTS: The midline method had larger CMAP amplitudes on both sides and a stronger negative correlation in the relationship between the ENoG value and period to full recovery from palsy than the standard method statistically.


Assuntos
Paralisia Facial/diagnóstico , Paralisia Facial/fisiopatologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Eletrodiagnóstico/instrumentação , Eletromiografia , Potenciais Evocados , Músculos Faciais/inervação , Músculos Faciais/fisiopatologia , Nervo Facial/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
18.
Muscle Nerve ; 37(6): 764-9, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18506721

RESUMO

To establish a simple, reproducible procedure for studying facial motor nerve conduction (MNC), we determined the optimal electrode position to record evoked compound muscle action potentials (CMAPs) from perioral muscles in normal subjects. We examined three new electrode positions in which the electrode connected to the one input of the amplifier was placed on the mental protuberance, and the one connected to the other input was placed on the skin over the orbicularis oris muscle (the philtrum, mouth angle, or lower lip). We then compared the morphology and amplitudes of the CMAPs, right-left differences, and the reproducibility of CMAP amplitudes with recordings taken from the standard electrode position in which one electrode was placed on the nasolabial fold closely lateral to the ala nasi, and the other was placed on the skin over the orbicularis oris. Percutaneous supramaximal electrical stimulation was applied to the main trunk of the facial nerve. All three of the new recording positions showed greater amplitudes and more obvious biphasic CMAPs than the standard method. Positioning the electrode connected to the negative input on the philtrum was optimal in terms of right-left differences and the reproducibility of CMAP amplitudes. Therefore, this midline recording is a simple, reproducible method for calculating the CMAP amplitude ratio. However, prior to clinical use of this procedure, analyses of patients with facial palsy are required.


Assuntos
Potenciais de Ação/fisiologia , Músculos Faciais/fisiopatologia , Paralisia Facial/fisiopatologia , Adulto , Interpretação Estatística de Dados , Eletrodos , Eletrofisiologia , Feminino , Lateralidade Funcional/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Músculos Oculomotores/fisiopatologia , Reprodutibilidade dos Testes
19.
Radiat Prot Dosimetry ; 128(1): 98-105, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-17595212

RESUMO

The spread of Multi-detector-row computed tomography (MDCT) has been remarkable. Here, various organ and tissue doses were evaluated with six types of MDCT scanners in common use in Japan; using thermoluminescence dosimeters and anthropomorphic phantoms under condition of routine clinical examinations of the chest in adult and child, of the head in child and of the abdomen-pelvis in adult. Estimated lung doses and averaged effective dose in chest examinations were 19.2 +/- 2.03 mGy and 9.54 +/- 0.90 mSv for the adult and 15.7 +/- 1.88 mGy and 7.42 +/- 0.82 mSv for the child phantom, respectively. The numerical difference between effective dose and organ or tissue doses was about 2-2.5 times. For the adult abdomen-pelvis examinations, averaged effective dose was 13.0 +/- 3.72 mSv. Averaged effective dose for the child head examinations was 2.6 +/- 1.32 mSv. In one case, the dose approached 80 mGy for the brain in the head examination, giving a difference from the effective dose of 10 times or more.


Assuntos
Doses de Radiação , Radiometria/métodos , Tomografia Computadorizada por Raios X , Adolescente , Criança , Humanos , Imagens de Fantasmas , Eficiência Biológica Relativa , Dosimetria Termoluminescente
20.
Chirality ; 18(7): 483-8, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16683230

RESUMO

The racemic title host compound (1) formed homochiral inclusion crystals (conglomerate) of 1 with acetone, while heterochiral inclusion crystals (racemate) were obtained when complexed with ethyl acetate. Upon treatment of the homochiral inclusion crystals of 1 with gaseous acetyl chloride in the solid state, optically active 2,3-bis(fluorenylidene)succinic anhydride (3) was obtained in high optical purity.

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