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1.
Proc Natl Acad Sci U S A ; 116(45): 22458-22463, 2019 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-31641068

RESUMEN

This study investigates the evolution of superconductivity in K2-xFe4+ySe5 using temperature-dependent X-ray absorption and resonant inelastic X-ray scattering techniques. Magnetization measurements show that polycrystalline superconducting (SC) K1.9Fe4.2Se5 has a critical temperature (T c) of ∼31 K with a varying superconducting volume fraction, which strongly depends on its synthesis temperature. An increase in Fe-structural/vacancy disorder in SC samples with more Fe atoms occupying vacant 4d sites is found to be closely related to the decrease in the spin magnetic moment of Fe. Moreover, the nearest-neighbor Fe-Se bond length in SC samples exceeds that in the non-SC (NS) sample, K2Fe4Se5, which indicates a weaker hybridization between the Fe 3d and Se 4p states in SC samples. These results clearly demonstrate the correlations among the local electronic and atomic structures and the magnetic properties of K2-xFe4+ySe5 superconductors, providing deeper insight into the electron pairing mechanisms of superconductivity.

2.
Phys Rev Lett ; 113(21): 217203, 2014 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-25479519

RESUMEN

SmFeO3 has attracted considerable attention very recently due to its reported multiferroic properties above room temperature. We have performed powder and single crystal neutron diffraction as well as complementary polarization dependent soft X-ray absorption spectroscopy measurements on floating-zone grown SmFeO3 single crystals in order to determine its magnetic structure. We found a k=0 G-type collinear antiferromagnetic structure that is not compatible with inverse Dzyaloshinskii-Moriya interaction driven ferroelectricity. While the structural data reveal a clear sign for magneto-elastic coupling at the Néel-temperature of ∼675 K, the dielectric measurements remain silent as far as ferroelectricity is concerned.

3.
J Pathol ; 230(2): 154-64, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23620094

RESUMEN

DICER1 is an endoribonuclease central to the generation of microRNAs (miRNAs) and short interfering RNAs (siRNAs). Germline mutations in DICER1 have been associated with a pleiotropic tumour predisposition syndrome and Wilms tumour (WT) is a rare manifestation of this syndrome. Three WTs, each in a child with a deleterious germline DICER1 mutation, were screened for somatic DICER1 mutations and were found to bear specific mutations in either the RNase IIIa (n = 1) or the RNase IIIb domain (n = 2). In the two latter cases, we demonstrate that the germline and somatic DICER1 mutations were in trans, suggesting that the two-hit hypothesis of tumour formation applies for these examples of WT. Among 191 apparently sporadic WTs, we identified five different missense or deletion somatic DICER1 mutations (2.6%) in four individual WTs; one tumour had two very likely deleterious somatic mutations in trans in the RNase IIIb domain (c.5438A>G and c.5452G>A). In vitro studies of two somatic single-base substitutions (c.5429A>G and c.5438A>G) demonstrated exon 25 skipping from the transcript, a phenomenon not previously reported in DICER1. Further we show that DICER1 transcripts lacking exon 25 can be translated in vitro. This study has demonstrated that a subset of WTs exhibits two 'hits' in DICER1, suggesting that these mutations could be key events in the pathogenesis of these tumours.


Asunto(s)
ARN Helicasas DEAD-box/genética , Mutación de Línea Germinal , Neoplasias Renales/genética , Ribonucleasa III/genética , Tumor de Wilms/genética , Animales , Células COS , Preescolar , Chlorocebus aethiops , Exones , Femenino , Humanos , Neoplasias Renales/diagnóstico , Masculino , Mutación Missense , Tumor de Wilms/diagnóstico
4.
Int Endod J ; 47(4): 332-8, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23815501

RESUMEN

AIM: To test the ability of periapical radiography (PA) and cone-beam computed tomography (CBCT) to determine the presence/absence of periapical lesions and examine the reliability of volumetric measurements of periapical lesions on CBCT scans. METHODOLOGY: After tooth extractions in human mandibles, bone defects were cut at the base of extraction sockets to mimic periapical bone lesions. The teeth were then returned into the extraction sockets. Sixty-three roots of anterior teeth, premolars and molars with artificial periapical lesions and 37 roots without lesions were examined with PA and CBCT. Presence/absence of periapical lesion was noted. The CBCT-based volume of each lesion (Vct) was measured using Amira software 5.4 (Visage Imaging GmbH, Berlin, Germany). A replica of each lesion was created using silicone impression material, and the volume of the replica was measured using a water displacement method, representing the physical volume of the lesion (Vp). Regression analysis was used to test the correlation between the Vp and Vct values. RESULTS: The positive and negative predictive values and accuracy for CBCT in diagnosing periapical lesions were all 1, compared with 1, 0.64 and 0.79 for PA diagnosis. Twenty-one (33%) lesions were undetected by PA. The Vp (21.5 ± 11.0 mm(3) ) and Vct (21.4 ± 11.5 mm(3) ) values of 63 lesions were highly correlated (R(2) = 96.9%, P < 0.001). CONCLUSION: Cone-beam computed tomography is more accurate than PA in diagnosing periapical lesions associated with mandibular teeth. The volumes of artificial mandibular periapical lesions were accurately measured with CBCT data.


Asunto(s)
Pérdida de Hueso Alveolar/diagnóstico por imagen , Tomografía Computarizada de Haz Cónico , Mandíbula/diagnóstico por imagen , Enfermedades Periapicales/diagnóstico por imagen , Raíz del Diente/diagnóstico por imagen , Humanos , Técnicas In Vitro , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Extracción Dental
5.
Phys Rev Lett ; 108(14): 146102, 2012 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-22540808

RESUMEN

We use scanning tunneling microscopy and spectroscopy to measure the energy shift of empty quantum-well (QW) states in Pb islands on the Cu(111) surface. It is found that, with an increase of the electric field, the behavior of the energy shift can be grouped into two different modes for most QW states. In the first mode, the state energy moves toward high energy monotonically. In the second mode, the state energy shifts to a lower energy initially and then turns around to a higher energy. Moreover, we have observed that the QW states of higher energy behave in preference to the first mode, but they gradually change to the second mode as the Pb island becomes thicker. This thickness-dependent behavior reflects the existence of local expansion in the Pb islands, due to the electric field, and that the expansion is larger for a thicker island. QW states can thus be used for studying the localized lattice deformation in the nanometer scale.

6.
Phys Rev Lett ; 108(26): 267002, 2012 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-23005008

RESUMEN

We utilize steady-state and transient optical spectroscopies to examine the responses of nonthermal quasiparticles with respect to orbital modifications in normal-state iron-chalcogenide superconductors. The dynamics shows the emergence of gaplike quasiparticles (associated with a ~36 meV energy gap) with a coincident transfer of the optical spectral weight in the visible range, at temperatures above the structural distortion. Our observations suggest that opening of the high-temperature gap and the lattice symmetry breaking are possibly driven by short-range orbital and/or charge orders, implicating a close correlation between electronic nematicity and precursor order in iron-based superconductors.

7.
Int Endod J ; 45(8): 724-9, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22372870

RESUMEN

AIM: To compare the ability of cone-beam computed tomography (CBCT) and digital periapical radiographs (PR) to detect simulated tissue-occupied recesses in root canals. METHODOLOGY: A standard canal was created in 30 extracted mandibular premolar roots. Each root was longitudinally split into buccal and lingual halves. In 20 teeth, a standard groove, 4mm in length, 0.5mm deep and 0.3mm wide, was prepared on each root half and filled with radiolucent plasticine (a modelling clay), simulating tissue-occupied buccal and lingual recesses. In the other 10 teeth, no grooves were cut. Each root was reassembled and filled with laterally compacted gutta-percha and sealer. PR and CBCT were used to detect the plasticine-filled grooves. The images were pooled and blindly evaluated by three calibrated examiners (A, B and C). A chi-square test was used to analyse the data. RESULTS: Examiner A, B, C detected grooves on CBCT scans in 20, 20 and 23 teeth, respectively, of which 19, 18 and 19 were true positives. The accuracy of CBCT in diagnosing plasticine-filled grooves was 82-92% for three examiners, significantly higher than the accuracy of PR (30-33%; P<0.001). CONCLUSIONS: Cone-beam computed tomography accurately detected simulated tissue-occupied buccal and lingual recesses.


Asunto(s)
Tomografía Computarizada de Haz Cónico/métodos , Cavidad Pulpar/diagnóstico por imagen , Radiografía de Mordida Lateral/métodos , Radiografía Dental Digital/métodos , Diente Premolar/diagnóstico por imagen , Reacciones Falso Negativas , Reacciones Falso Positivas , Gutapercha/uso terapéutico , Humanos , Valor Predictivo de las Pruebas , Materiales de Obturación del Conducto Radicular/uso terapéutico , Preparación del Conducto Radicular/métodos , Sensibilidad y Especificidad
8.
Phys Chem Chem Phys ; 13(34): 15666-72, 2011 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-21804990

RESUMEN

Critical issues concerning emerging Fe-based superconductors include the degree of electron correlation and the origin of the superconductivity. X-Ray absorption spectra (XAS) and resonant inelastic X-ray scattering spectra (RIXS) of FeSe(1-x)Te(x) (x = 0-1) single crystals were obtained to study their electronic properties that relate to electron correlation and superconductivity. The linewidth of Fe L(2,3)-edges XAS of FeSe(1-x)Te(x) is narrower than that of Fe-pnictides, revealing the difference between their hybridization effects and localization character and those of other Fe-pnictides. While no significant differences exist between the Fe L-edge XAS and RIXS of FeSe(1-x)Te(x) and those of Fe-pnictides, Se K-edge and Te K-edge XAS exhibit substantial edge shift, suggesting that the superconductivity in an Fe-Se superconductor is strongly associated with the ligand states. A comparison of the Se K-edge and Te K-edge spectra reveals that the charge transfer may occur between Se and Te. Given the Coulomb interaction and the bandwidth, the spectral results indicate that FeSe(1-x)Te(x) is unlikely to be a weakly correlated system unlike the Fe-pnictides of the "1111" and "122" families. The spectral results further demonstrate that superconductivity in this class of Fe-based compounds is strongly associated with the ligand 4p hole state.

9.
Int Endod J ; 44(5): 395-401, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21219359

RESUMEN

AIM: To assess differences in observed cross-sectional areas of root canals and filling materials, as imaged by three microscopy and two tomography methods. METHODOLOGY: Six roots filled with laterally compacted Gutta-percha and AH26 were scanned with phase-contrast enhanced microtomography in a synchrotron facility. Reconstructed virtual slices were compared with sections of both wet and acrylic-embedded roots, evaluated also by light and electron microscopy (EM) and laboratory-based microtomography (µCT). The different contrasts of Gutta-percha, voids, sealer and root dentine were identified and correlated. Inner canal border, outer Gutta-percha rim and the external margin of a void were manually delineated, and the enclosed areas were repeatedly measured by three observers. Interobserver and interimaging method differences were tested by 2-way anova with Bonferroni adjustments (P < 0.05). Percentages of Gutta-percha-filled canal areas (PGP) were determined. RESULTS: Phase-contrast enhanced microtomography revealed internal interfaces and detailed 3D volumes of accentuated voids as well as micrometre-sized particles and gaps within the treated roots. Overestimates in the cross-sectional areas were obtained by light microscopy, whereas underestimates were obtained by µCT and EM. Differences exceeded 40%; however, PGP values by all methods were within 5% for the same slice. Differences between observers were sometimes significant, but they were not method related (<3%). CONCLUSIONS: Phase-contrast enhanced microtomography is a powerful non-destructive ex vivo investigation method for studying the interfaces within root canals and filling materials at a micrometre resolution. The method does not require damage-prone sectioning/polishing during sample preparation procedures. Caution should be used when quantifying the extent of Gutta-percha in root fillings by measurements using µCT, light and EM.


Asunto(s)
Adaptación Marginal Dental/normas , Cavidad Pulpar/diagnóstico por imagen , Materiales de Obturación del Conducto Radicular/normas , Obturación del Conducto Radicular/normas , Microtomografía por Rayos X/métodos , Análisis de Varianza , Anatomía Transversal , Cavidad Pulpar/ultraestructura , Procesamiento de Imagen Asistido por Computador , Microscopía de Contraste de Fase , Estadísticas no Paramétricas , Microtomografía por Rayos X/instrumentación
10.
Sci Rep ; 11(1): 12624, 2021 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-34135360

RESUMEN

In this paper, the distribution of relaxation times (DRTs) functions are calculated numerically in Matlab for synthetic impedance data from single parallel [Formula: see text] circuit and two parallel [Formula: see text] circuits connected in series, experimental impedance data from supercapacitors and α-LiFeO2 anode based Li ion batteries. The quality of the impedance data is checked with the Kramers-Krönig (KK) relations. The DRTs are calculated within the KK compatible regime for all the systems using Tikhonov regularization (TR) method. Here we use a fast and simple L-curve method to estimate the TR parameter (λ) for regularization of the Fredholm integral equations of first kind in impedance. Estimation of the regularization parameters are performed effectively from the offset of the global corner of the L-curve rather than simply using the global corner. The physical significances of DRT peaks are also discussed by calculating the effective resistances and capacitances coupled with peak fitting program. For instance, two peaks in the DRTs justify the electrical double layer capacitance and ion diffusion phenomena for supercapacitors in low to intermediate frequencies respectively. Moreover, the surface film effect, Li/electrolyte and electrode/electrolyte charge transfer related processes are identified for α-LiFeO2 anode based Li-ion batteries. This estimation of the offset of the global corner extends the L-curve approach coupled with the Tikhonov regularization in the field of electrochemistry and can also be applied in similar process detection methods.

11.
Artículo en Zh | MEDLINE | ID: mdl-33472303

RESUMEN

Objective: To compare the clinical characteristics of patients with different type of laryngopharyngeal reflux disease in order to study the effect of non-acid reflux on laryngopharyngeal reflux disease. Methods: From January 2015 to January 2020, 349 inpatients or outpatients suspected of having laryngopharyngeal reflux underwent 24-hour multichannel intraluminal impedance pH monitoring (MII-pH). There were 303 male and 46 female patients, with an average age of 56.03 years old ranged from 25 to 81 years old. The reflux symptom index (RSI)and reflux findings score(RFS)were recorded before MII-pH monitoring. The number of acid reflux events and non-acid reflux events in hypopharynx were counted. It was defined mainly acid reflux type when the ratio of acid reflux to all reflux events was greater than 50%, mainly non-acid reflux type when the ratio of non-acid reflux to all reflux events was greater than 50%. The clinical characteristics of patients with different type of reflux were compared. SPSS 19.0 software was used for statistical analysis, and multiple independent samples were compared between groups. The quantitative data were analyzed by multivariate analysis of variance, and the counting data were analyzed by chi-square test, the difference was statistically significant when P<0.05. Results: The 24-hour MII-pH showed that there were 90 patients with no reflux events, 51 patients with mainly acid reflux type, 198 patients with mainly non-acid reflux type and 10 patients with equal acid reflux events and non-acid reflux events. Statistics showed that the RSI(10.72±4.40), RFS(7.70±2.73) and the average number of reflux events(0) in the group without reflux events were significantly lower than those in patients with mainly acid reflux type (RSI 13.16±6.62,RFS 10.08±3.03,average number of reflux events 5.33±3.15,P<0.05) and mainly non-acid reflux type(RSI 13.25±5.54,RFS 8.81±2.54,average number of reflux events 7.93±5.26, P<0.05). There was no significant difference in RSI between the mainly non-acid reflux type group and the mainly acid reflux type group, but the RFS of the mainly non-acid reflux type group was significantly lower than that of the mainly acid reflux type group. The average number of reflux events in the mainly non-acid reflux group was significantly higher than that in the mainly acid reflux type group (P<0.05). Conclusion: The results show that non-acid reflux plays a certain role in laryngopharyngeal reflux disease, but the effect of acid reflux is greater.


Asunto(s)
Reflujo Laringofaríngeo , Adulto , Anciano , Anciano de 80 o más Años , Monitorización del pH Esofágico , Femenino , Humanos , Hipofaringe , Reflujo Laringofaríngeo/diagnóstico , Reflujo Laringofaríngeo/epidemiología , Masculino , Persona de Mediana Edad , Sistema Respiratorio
12.
Nat Commun ; 12(1): 5436, 2021 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-34521833

RESUMEN

The rich phenomena in the FeSe and related compounds have attracted great interests as it provides fertile material to gain further insight into the mechanism of high temperature superconductivity. A natural follow-up work was to look into the possibility of superconductivity in MnSe. We demonstrated in this work that high pressure can effectively suppress the complex magnetic characters of MnSe, and induce superconductivity with Tc ~ 5 K at pressure ~12 GPa confirmed by both magnetic and resistive measurements. The highest Tc is ~ 9 K (magnetic result) at ~35 GPa. Our observations suggest the observed superconductivity may closely relate to the pressure-induced structural change. However, the interface between the metallic and insulating boundaries may also play an important role to the pressure induced superconductivity in MnSe.

13.
Int Endod J ; 43(11): 995-1000, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20722755

RESUMEN

AIM: To compare the incidence of dentinal defects (cracks and craze lines) after root canal preparation, lateral compaction and continuous wave compaction of gutta-percha and AH26 sealer. METHODOLOGY: Two hundred mandibular premolar teeth were divided into four groups with similar average canal diameters (n=50). One group was left untreated and served as the control. The other three groups were prepared with ProTaper rotary instruments up to size F4. After preparation, one group was left unfilled while two groups were filled with gutta-percha and AH26 using either lateral compaction or the continuous wave technique. Roots were then sectioned at 3, 6 and 9 mm from the apex and inspected under a microscope. The appearance of dentinal defects was noted as well as the minimum and mean remaining dentine thickness. Chi-square tests were performed to compare the incidence of dentinal defects between the groups (α=0.05), and Pearson correlation test was performed to check the correlation between defects and root level or remaining dentine thickness. RESULTS: The unprepared control group had no dentinal defects. The other groups exhibited significantly more defects than the unprepared group (P<0.05). There was no difference in the incidence of defects between the two filling techniques. There was no correlation between the appearance of defects and level of the root or remaining dentine thickness. CONCLUSIONS: In extracted teeth, dentinal defects were observed in roots filled with gutta-percha and AH26 using the lateral compaction and continuous wave techniques.


Asunto(s)
Cavidad Pulpar/lesiones , Dentina/lesiones , Obturación del Conducto Radicular/efectos adversos , Bismuto/efectos adversos , Cavidad Pulpar/patología , Dentina/patología , Resinas Epoxi/efectos adversos , Gutapercha/efectos adversos , Humanos , Ensayo de Materiales , Materiales de Obturación del Conducto Radicular/efectos adversos , Irrigantes del Conducto Radicular/uso terapéutico , Obturación del Conducto Radicular/métodos , Preparación del Conducto Radicular/efectos adversos , Preparación del Conducto Radicular/instrumentación , Plata/efectos adversos , Hipoclorito de Sodio/uso terapéutico , Irrigación Terapéutica , Titanio/efectos adversos , Ápice del Diente/lesiones , Ápice del Diente/patología , Ultrasonido
14.
J Phys Condens Matter ; 21(23): 232201, 2009 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-21825575

RESUMEN

High pressure superconductivity in iron-based superconductor FeSe(0.5)Te(0.5) has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (T(c)) at 14 K at ambient pressure with T(c) increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, T(c) decreases and extrapolation suggests non-superconducting behavior above 10 GPa. The loss of superconductivity coincides with the pressure induced disordering of the Fe(SeTe)(4) tetrahedra reported at 11 GPa in x-ray diffraction studies at ambient temperature.

15.
Int Endod J ; 42(8): 656-66, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19548929

RESUMEN

The aim of this work was to identify the limitations of previously published systematic reviews evaluating the outcome of root canal treatment. Traditionally, periapical radiography has been used to assess the outcome of root canal treatment with the absence of a periapical radiolucency being considered a confirmation of a healthy periapex. However, a high percentage of cases confirmed as healthy by radiographs revealed apical periodontitis on cone beam computed tomography (CBCT) and by histology. In teeth, where reduced size of the existing radiolucency was diagnosed by radiographs and considered to represent periapical healing, enlargement of the lesion was frequently confirmed by CBCT. In clinical studies, two additional factors may have further contributed to the overestimation of successful outcomes after root canal treatment: (i) extractions and re-treatments were rarely recorded as failures; and (ii) the recall rate was often lower than 50%. The periapical index (PAI), frequently used for determination of success, was based on radiographic and histological findings in the periapical region of maxillary incisors. The validity of using PAI for all tooth positions might be questionable, as the thickness of the cortical bone and the position of the root tip in relation with the cortex vary with tooth position. In conclusion, the serious limitations of longitudinal clinical studies restrict the correct interpretation of root canal treatment outcomes. Systematic reviews reporting the success rates of root canal treatment without referring to these limitations may mislead readers. The outcomes of root canal treatment should be re-evaluated in long-term longitudinal studies using CBCT and stricter evaluation criteria.


Asunto(s)
Estudios de Evaluación como Asunto , Evaluación de Resultado en la Atención de Salud , Literatura de Revisión como Asunto , Tratamiento del Conducto Radicular , Tomografía Computarizada de Haz Cónico , Fracaso de la Restauración Dental , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Periodontitis Periapical/diagnóstico por imagen , Radiografía Dental/métodos , Retratamiento , Extracción Dental
16.
Int Endod J ; 42(3): 208-13, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19228210

RESUMEN

AIM: To evaluate ex vivo the incidence of defects in root dentine before and after root canal preparation and filling. METHODOLOGY: Eighty extracted mandibular premolars were divided equally in four groups. Group 1 was left unprepared. All other root canals were prepared using Gates Glidden drills and System GT files up to size-40, 0.06 taper at the working length. Group 2 was not filled while the canals of the other groups were filled with gutta-percha and AH26, either with a master cone and passive insertion of secondary gutta percha points (group 3) or lateral compaction (group 4). Roots were then sectioned horizontally 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects (fractures, craze lines or incomplete cracks) was noted and the differences between the groups were analysed with the Fisher's exact test. RESULTS: No defects were observed in the roots with unprepared canals. The overall difference between the groups was significant (P < 0.05). Canal preparation alone created significantly more defects than unprepared canals (P < 0.05). The total number of defects after lateral compaction was significantly larger than after noncompaction canal filling. CONCLUSION: Root canal preparation and filling of extracted teeth created dentine defects such as fractures, craze lines and incomplete cracks.


Asunto(s)
Cavidad Pulpar/lesiones , Dentina/lesiones , Preparación del Conducto Radicular/métodos , Diente Premolar , Bismuto/uso terapéutico , Combinación de Medicamentos , Resinas Epoxi/uso terapéutico , Diseño de Equipo , Gutapercha/uso terapéutico , Humanos , Ensayo de Materiales , Materiales de Obturación del Conducto Radicular/uso terapéutico , Irrigantes del Conducto Radicular/uso terapéutico , Obturación del Conducto Radicular/efectos adversos , Obturación del Conducto Radicular/métodos , Preparación del Conducto Radicular/efectos adversos , Preparación del Conducto Radicular/instrumentación , Plata/uso terapéutico , Hipoclorito de Sodio/uso terapéutico , Titanio/uso terapéutico , Fracturas de los Dientes/etiología , Fracturas de los Dientes/patología
17.
Int Endod J ; 42(8): 719-26, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19467040

RESUMEN

AIM: To determine the influence of filling technique and root canal area on the percentage of gutta-percha (PGP) in laterally compacted root fillings. METHODOLOGY: Sixty extracted canine teeth were accessed and the root canals instrumented to the same size. They were then divided in three groups and filled with laterally compacted gutta-percha cones and AH Plus using different techniques. A variation of cold lateral compaction using a sequence of spreaders prior to accessory cone placement was compared to two commonly-used techniques. Twenty additional canines with prepared root canals were used as negative controls in which gutta-percha was introduced into the canals but no compaction applied. The roots were sectioned horizontally at 3 and 6 mm from the apex and micro-photographs taken. Using software, the area of the canals and gutta-percha at each level were measured and PGP calculated. A Multivariate analysis was used to determine the variables influencing PGP. A linear regression test was used to verify the variation in PGP explained by canal area. RESULTS: At each level the largest canal was two to three times wider than the smallest. Canal area significantly influenced the PGP at both levels (P < 0.05), however, the variation in PGP was only partially explained by canal area (r(2) = 0.154, 6 mm; r(2) = 0.119, 3 mm). The PGP at the 3 mm level was lower than at 6 mm (P = 0.003). The spreader-sequence technique achieved a higher PGP than the other two techniques (P = 0.00002). The control group had the lowest area of GP. CONCLUSIONS: Variations in root canal filling technique and canal area influenced the percentage of gutta-percha of laterally compacted root fillings. The percentage of gutta-percha was lower at the 3 mm level compared to the 6 mm level.


Asunto(s)
Cavidad Pulpar/anatomía & histología , Gutapercha/análisis , Materiales de Obturación del Conducto Radicular/análisis , Obturación del Conducto Radicular/métodos , Diente Canino , Resinas Epoxi , Humanos , Modelos Lineales , Fotografía Dental , Obturación del Conducto Radicular/instrumentación
18.
Int Endod J ; 42(12): 1077-83, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19912378

RESUMEN

AIM: To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. METHODOLOGY: Root canals with a standardized groove in one canal wall filled with dentine debris were irrigated with syringe irrigation, ultrasonically or laser-activated irrigation (LAI) using 2% sodium hypochlorite as irrigant. The quantity of dentine debris after irrigation was determined. Visualization of the fluid dynamics during activation was achieved using a high-speed camera and a glass model. RESULTS: Laser-activated irrigation was significantly more effective in removing dentine debris from the apical part of the root canal than passive ultrasonic irrigation or hand irrigation when the irrigant was activated for 20 s. CONCLUSIONS: The in vitro recordings suggest that streaming, caused by the collapse of the laser-induced bubble, is the main cleaning mechanism of LAI.


Asunto(s)
Rayos Láser , Fotografía Dental/instrumentación , Irrigantes del Conducto Radicular/administración & dosificación , Preparación del Conducto Radicular/instrumentación , Diente Canino , Análisis del Estrés Dental , Dentina , Humanos , Microburbujas , Reología , Capa de Barro Dentinario , Hipoclorito de Sodio/administración & dosificación , Jeringas , Irrigación Terapéutica/instrumentación , Ápice del Diente , Ultrasonido
19.
Artículo en Zh | MEDLINE | ID: mdl-31315356

RESUMEN

Objective: To evaluate the feasibility of pepsin strip test in the diagnosis of laryngopharyngeal reflux. Methods: From August 2017 to September 2018,80 patients in Department of Otorhniolaryngology Head and Neck Surgery,Chinese People's Liberation Army General Hospital-Six Medical Centre, underwent pepsin strip test and 24-hour multichannel intraluminal impedance(MII)-pH monitoring. The results of the two methods were analyzed for consistency,and 24-hour MII-pH monitoring was used as a statistical reference for the sensitivity and specificity of pepsin strip test in the diagnosis of laryngopharyngeal reflux. Data were analyzed by SPSS 19.0 software. Results: There were 57 patients with positive pepsin test strip and 23 patients with negative pepsin test strip. The score of reflux symptoms and signs, and the positive rate of laryngopharyngeal reflux events in patients with positive pepsin strip test were significantly higher than those in patients with negative pepsin test strip. If there was one or more throat reflux events (including acid reflux,weak acid reflux and alkali reflux) as the positive results of 24-hour MII-pH monitoring,the consistency between the results of pepsin strip and 24-hour MII-pH was moderate (Kappa=0.614). The sensitivity and specificity of pepsin strip were 86.9% (53/61) and 78.9% (15/19) respectively. Conclusions: Pepsin strip detection has the advantages of non-invasive,cheap and easy to operate.As an objective method for early diagnosis of laryngopharyngeal reflux, pepsin strip detectionis feasible,but can not be the final diagnosis for laryngopharyngeal reflux disease.


Asunto(s)
Reflujo Laringofaríngeo/diagnóstico , Pepsina A/análisis , Tiras Reactivas/química , Impedancia Eléctrica , Monitorización del pH Esofágico , Estudios de Factibilidad , Humanos , Reflujo Laringofaríngeo/fisiopatología
20.
Int J Obes (Lond) ; 32(3): 436-42, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17955031

RESUMEN

OBJECTIVE: Obese patients with schizophrenia being treated with clozapine and non-psychiatric obese are often assumed to share the same physiological changes in obesity. The aim of this study was to identify possible metabolic and hormonal differences between non-psychiatric obese subjects (OB) and obese patients with schizophrenia being treated with clozapine (OSC). SUBJECTS: Fifty-one normal healthy subjects (Nor, body mass index (BMI):23.2+/-0.3), 50 OB (BMI:31.7+/-0.7) and 71 OSC (BMI:30.4+/-0.5). MEASUREMENTS: Anthropometric, metabolic and hormonal parameters were determined by anthropometry, enzyme autoanalyzer, immunoassay and enzyme-linked immunosorbent assay. RESULTS: Triglyceride, total cholesterol divided by high-density lipoprotein (HDL) cholesterol (TC/HDL) and leptin levels were significantly higher whereas the HDL and the molar ratio of insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein (IGFBP)-3 levels were significantly lower in both OB and OSC groups than those in the Nor group. Compared to normal subjects, insulin and homeostasis model assessment (HOMA) index levels were significantly higher in OSC, and, in OSC, insulin sensitivity and insulin-like growth factor (IGF)-1 were significantly lower. Although the anthropometric parameters in the OB and OSC groups were similar, in the OSC group the waist-to-hip ratio (WHR), insulin levels and HOMA index were significantly higher, while insulin sensitivity, cholesterol, low-density lipoprotein (LDL) cholesterol, TC/HDL, LDL/HDL, IGF-1 and IGF-1/IGFBP-3 molar ratio were lower, than those of the OB group. CONCLUSION: Insulin homeostasis and lipid profiles in clozapine-treated schizophrenic obesity were different from those in non-psychiatric obesity with similar anthropometric parameters, body weight and BMI. Among the three groups, the highest fasting insulin, the lowest insulin sensitivity and the highest HOMA index occurred in the OSC group. The OSC group was characterized by impaired glucose-insulin homeostasis, abnormal lipid profiles and hormonal changes in the GH-IGF-IGFBP axis and in leptin.


Asunto(s)
Glucemia/metabolismo , Insulina/metabolismo , Lípidos/sangre , Obesidad/metabolismo , Esquizofrenia/metabolismo , Adolescente , Adulto , Anciano , Antipsicóticos/uso terapéutico , Índice de Masa Corporal , Pesos y Medidas Corporales , Clozapina/uso terapéutico , Ensayo de Inmunoadsorción Enzimática , Femenino , Homeostasis , Humanos , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leptina/metabolismo , Masculino , Persona de Mediana Edad , Obesidad/psicología , Esquizofrenia/complicaciones , Esquizofrenia/tratamiento farmacológico
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