Pressure induced superconductivity in MnSe.

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.

Computation of distribution of relaxation times by Tikhonov regularization for Li ion batteries: usage of L-curve method.

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.

[Comparison of clinical characteristics of patients with different types of laryngopharyngeal reflux disease].

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.

Evolution of superconductivity in K2-xFe4+ySe5: Spectroscopic studies of X-ray absorption and emission.

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.

[Feasibility analysis of pepsin strip test in diagnosis of laryngopharyngeal reflux disease].

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.

[Observational study on patients with laryngeal cancer and/or vocal leukoplakia concurrent with laryngopharyngeal reflux].

Objective: To observe the incidence and to determine the significance of laryngopharyngeal reflux (LPR) in laryngeal cancer and vocal leukoplakia. Methods: The patients who had been diagnosed as laryngeal cancer or vocal leukoplakia between January 2014 and June 2017 were included in this study. All of them received 24-hour multichannel intraluminal impedance-pH monitoring. The prevalence of LPR and numerous parameters from the 24-hour pH monitoring in laryngeal cancer patient and vocal leukoplakia patient groups were analyzed. The chi-square test was used for counting data, t test and Mann-Whitney U were used for measuring data. Results: In the 91 laryngeal cancer patients, the prevalence of pathologic LPR was 28.6%(26/91), the median number[P(25), P(75), P(95)]of acid reflux events was 0[0, 3, 5], time of acid exposure was 0[0, 14, 234]s, number of weakly acidic reflux events was 3[0, 6, 11]. In the 54 vocal leukoplakia patients, the prevalence of pathologic LPR was 29.6%(16/54), the number of acid reflux events was 0[0, 3, 4], time of acid exposure was 0[0, 13, 118]s, number of weakly acidic reflux events was 1.5[0, 5, 9]. The incidence of LPR did not vary in the laryngeal cancer patient and vocal leukoplakia patient groups, but were both higher than healthy Chinese volunteers according to a report in the other literature. Furthermore, all the three patients with no history of tobacco or alcohol existed acid or weakly acidic reflux episodes. Conclusions: Laryngopharyngeal reflux might play a role as an etiologic factor in laryngeal cancer and vocal leukoplakia.

Electronic and atomic structures of the Sr3Ir4Sn13 single crystal: A possible charge density wave material.

X-ray scattering (XRS), x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopic techniques were used to study the electronic and atomic structures of the high-quality Sr3Ir4Sn13 (SIS) single crystal below and above the transition temperature (T* ≈ 147 K). The evolution of a series of modulated satellite peaks below the transition temperature in the XRS experiment indicated the formation of a possible charge density wave (CDW) in the (110) plane. The EXAFS phase derivative analysis supports the CDW-like formation by revealing different bond distances [Sn1(2)-Sn2] below and above T* in the (110) plane. XANES spectra at the Ir L3-edge and Sn K-edge demonstrated an increase (decrease) in the unoccupied (occupied) density of Ir 5d-derived states and a nearly constant density of Sn 5p-derived states at temperatures T < T* in the (110) plane. These observations clearly suggest that the Ir 5d-derived states are closely related to the anomalous resistivity transition. Accordingly, a close relationship exists between local electronic and atomic structures and the CDW-like phase in the SIS single crystal.

Successive spin orderings of tungstate-bridged Li2Ni(WO4)2 of spin 1.

Magnetic, thermodynamic, and dielectric properties of Li2Ni(WO4)2 of S = 1 system have been studied using magnetic susceptibility, specific heat, and dielectric constant measurements. The magnetic orderings can be identified in three stages, including a short range magnetic ordering indicated by the rounded χ(T) peak with maximum at ∼20 K, and signatures of two successful antiferromagnetic long range orderings near T(N1) ~ 18 K and T(N2) ~ 13 K revealed by the d(χ(T)) /d(T) peaks. The successive long range magnetic orderings are related to the quasi triangular symmetry breaking in the ac- and bc-planes and to the change of the dielectric constant, suggesting the presence of spin-phonon coupling. The specific heat and magnetic entropy analysis for Li2Ni(WO4)2 shows the existence of a significant low dimensional magnetic correlations at high temperature and confirms the long range three-dimensional (3D) behavior of magnetic orderings below T(N1) and T(N2).

k=0 magnetic structure and absence of ferroelectricity in SmFeO3.

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.

Detection and measurement of artificial periapical lesions by cone-beam computed tomography.

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.

Biallelic DICER1 mutations occur in Wilms tumours.

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.

Gap opening and orbital modification of superconducting FeSe above the structural distortion.

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.

Field-induced expansion deformation in Pb islands on Cu(111): evidence from energy shift of empty quantum-well states.

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.

The ability of cone-beam computed tomography to detect simulated buccal and lingual recesses in root canals.

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.

X-Ray spectra and electronic correlations of FeSe(1-x)Te(x).

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.

Identification of root filling interfaces by microscopy and tomography methods.

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.

Incidence of dentinal defects after root canal filling procedures.

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.