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There is few study evaluating the relationship between endoscopic submucosal dissection (ESD) resection speed and the lesion characteristics of gastric neoplasia. We investigated the learning curve of consecutive ESDs using cumulative sum (CUSUM) analysis.A total of 356 ESDs performed by a single endoscopist were grouped chronologically into three learning periods. The ESD procedure was defined to be fast when resection speed was 9.0 cmMean resection speed was significantly faster in Phase III (15.1 cmThe time required to achieve relevant competency in gastric ESD depends on the tumor location.

We theoretically evaluate the performance of spurious-tone suppression of a multi-loop optoelectronic oscillators (MOEO) based on closed-loop analysis. Spurious tones are unwanted oscillation signals due to the cavity effect of long-length optical fiber and the severe drawbacks of optoelectronic oscillator (OEO). The spurious tones can be suppressed using the MOEO configuration with two controllable loop parameters of length and power ratios between multiple loops. We propose the method of closed-loop analysis to accurately extract the loop parameters and to increase spurious-tone suppression ratio (SSR). We successfully evaluated the MOEO performances with various loop-power ratios and achieved an SSR of 86 dB with a phase noise of -115 dBc/Hz at 10 kHz offset for a triple-loop OEO configuration by extracting the optimum power ratio of 0.332:0.131:0.537.

Background The ABC test measures serum pepsinogen and anti-Helicobacter pylori IgG antibody levels to predict precancerous conditions in the stomach and gastric cancer. However, a limitation of this test is that the gastric cancer risk is not negligible in patients with a negative result. Methods Based on their ABC results, 1157 patients were classified into Groups A (n = 392), B (n = 479), C (n = 247), and D (n = 39). In Group A, 24.2% of patients had atrophic gastritis and/or intestinal metaplasia and had thus been incorrectly assigned to Group A. Patients in Group A were then assigned to derivation (n = 236) and validation (n = 156) cohorts by 3:2 random sampling. Logistic regression analyses were performed to identify the factors discriminating between a correct (true) and incorrect (false) Group A classification. Results A 4-point discriminative model was constructed based on a high-negative H. pylori IgG antibody titer and the patient's age (50-64 and ≥65 years). The areas under the receiver operating characteristic curve for the derivation and validation cohorts were 0.868 and 0.894, respectively. In the validation cohort, the addition of a discriminative model score ≥2 to the ABC method showed a similar accuracy for predicting gastric cancer risk compared with the ABC method alone (93.8% vs. 92.4%). Conclusion The 4-point discriminative model may help identify patients with a normal serological test who are nonetheless at risk of developing gastric cancer.

Background Advances in endoscopic imaging enable the identification of patients at high risk of gastric cancer. However, there are no comparative data on the utility of standard and magnifying narrow-band imaging (M-NBI) endoscopy for diagnosing Helicobacter pylori (H. pylori) infection, gastric atrophy, and intestinal metaplasia. Aim To compare the diagnostic performance of standard and M-NBI endoscopy for H. pylori gastritis and precancerous conditions. Methods In 254 patients, standard endoscopy findings were classified into mosaic-like appearance (type A), diffuse homogenous redness (type B), and irregular redness with groove (type C). Gastric mucosal patterns visualized by M-NBI were classified as regular round pits with polygonal sulci (type Z-1), more dilated and linear pits without sulci (type Z-2), and loss of gastric pits with coiled vessels (type Z-3). Results The diagnostic accuracy of standard and M-NBI endoscopy for H. pylori gastritis was 93.3% and 96.1%, respectively. Regarding gastric precancerous conditions, the accuracy of standard and M-NBI endoscopy was 72.0% vs 72.6% for moderate to severe atrophy, and 61.7% vs. 61.1% for intestinal metaplasia in the corpus, respectively. Compared to type A and Z-1, types B+C and Z-2+Z-3 were significantly associated with moderate to severe atrophy [odds ratio (OR) = 5.56 and 8.67] and serum pepsinogen I/II ratio of ≤ 3 (OR = 4.48 and 5.69). Conclusion Close observation of the gastric mucosa by standard and M-NBI endoscopy is useful for the diagnosis of H. pylori gastritis and precancerous conditions.

Graphene has been the subject of much research, with structural engineering frequently used to harness its various properties. In particular, the concepts of graphene origami and kirigami have inspired the design of quasi-three-dimensional graphene structures, which possess intriguing mechanical, electronic, and optical properties. However, accurate controlling the folding process remains a big challenge. Here, we report the discovery of spontaneous folding growth of graphene on the h-BN substrate via adopting a simple chemical vapor deposition method. Folded edges are formed when two stacked graphene layers share a joint edge at a growth temperature up to 1300 °C. Using first-principles density functional theory calculations, the bilayer graphene with folded edges is demonstrated to be more stable than that with open edges. Utilizing this novel growth mode, hexagram bilayer graphene containing entirely sealed edges is eventually realized. Our findings provide a route for designing graphene devices with a new folding dimension.

The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high- $$T_{\rm{c}}$$ T c superconductivity at high pressure. Recently, cerium hydride $$\hbox {CeH}_9$$ CeH 9 composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80–100 GPa, compared to other experimentally synthesized rare-earth hydrides such as $$\hbox {LaH}_{{10}}$$ LaH 10 and $$\hbox {YH}_6$$ YH 6 . Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of $$\hbox {CeH}_9$$ CeH 9 .

Premalignant gastric lesions such as atrophic gastritis and intestinal metaplasia frequently occur in subjects with long-term Helicobacter pylori (H. pylori) infection. The regular arrangement of collecting venules (RAC) is seen in the normal gastric corpus, whereas mucosal swelling and redness without RAC are observed in H. pylori-infected mucosa. Despite successful H. pylori eradication, the presence of atrophic gastritis and/or gastric intestinal metaplasia (GIM) is a risk factor for gastric cancer. With the development of advanced imaging technologies, recent studies have reported the usefulness of narrow-band imaging (NBI) for endoscopic diagnosis of atrophic gastritis and GIM. Using NBI endoscopy with magnification (M-NBI), atrophic gastritis is presented as irregular coiled microvessels and loss of gastric pits. Typical M-NBI endoscopic findings of GIM are a light blue crest and a white opaque substance. Based on the microvascular patterns, fine network, core vascular, and unclear patterns are useful for predicting gastric dysplasia in polypoid lesions. For diagnosis of early gastric cancer (EGC), a systematic classification using M-NBI endoscopy has been proposed on the basis of the presence of a demarcation line and an irregular microvascular/microsurface pattern. Furthermore, M-NBI endoscopy has been found to be more accurate for determining the horizontal margin of EGC compared to conventional endoscopy. In this review, we present up-to-date results on the clinical usefulness of gastroscopy with NBI for the diagnosis of H. pylori gastritis, precancerous gastric lesion, and neoplasia.

BACKGROUND AND AIM This study investigated the usefulness of near-focus narrowband imaging (NF-NBI) for determining gastric tumor margins compared with indigo carmine chromoendoscopy (ICC) before endoscopic submucosal dissection (ESD). METHODS This prospective randomized controlled trial was conducted at seven teaching hospitals in Korea. Patients with gastric adenoma or differentiated adenocarcinoma undergoing ESD were enrolled and randomly assigned to the NF-NBI or ICC group. A marking dot was placed on the most proximal margin of the tumor before ESD. The primary endpoint was delineation accuracy, which was defined as presence of marking dots within 1 mm of the tumor margin under microscopic observation. RESULTS A total of 200 patients in the NF-NBI group and 195 patients in the ICC group were included. The delineation accuracy rate was 84.5% in the NF-NBI group and 81.0% in the ICC group (P = 0.44). However, the distance from the marking dot to the margin of the tumor was significantly shorter in the NF-NBI group than in the ICC group (0.8 ± 0.8 vs 1.2 ± 1.3 mm, P

To decrease gastric cancer-related mortality, the Korean National Cancer Screening Program provides biennial screening gastroscopy to all individuals aged >40 years. However, a test-and-treat strat...

Background/aims The eradication failure rate of standard triple therapy (proton pump inhibitor, clarithromycin, and amoxicillin) for Helicobacter pylori infection has increased owing to antibiotic resistance in Korea. We assessed whether Saccharomyces boulardii probiotic or broccoli sprout extract sulforaphane supplementation could increase the H. pylori eradication rate and/or reduce antibiotic-associated adverse events. Methods A total of 217 patients with H. pylori-positive chronic gastritis or peptic ulcer disease were recruited. Clarithromycin resistance was assessed in all patients by testing for A2142G and A2143G point mutations in H. pylori 23S rRNA using a dual-priming polymerase chain reaction (PCR) oligonucleotide. Thirty-four patients (17.3%) were clarithromycin-resistant and were excluded from the study. Finally, 183 patients with infections not resistant to clarithromycin were randomly assigned to triple therapy only (group A, n = 61), triple therapy plus probiotics (group B, n = 61), or triple therapy plus sulforaphane (group C, n = 61) groups. CYP2C19 polymorphisms were examined at position G681A of exon 5 and G636A of exon 4 by PCR with restriction fragment length polymorphism (PCR-RFLP) analysis. H. pylori eradication was assessed by 13C-urea breath test 4 weeks after treatment completion. Results The eradication rates were similar among the groups both in the intention- to-treat (A = 85.2%, B = 89.6%, and C = 81.6%) and per-protocol (A = 89.2%, B = 86.8%, and C = 96.3%) analyses. The frequencies of overall adverse events in the groups also did not differ (A vs. B: p = 0.574; A vs. C: p = 1.000). Conclusion Probiotic or sulforaphane with triple therapy for H. pylori infection neither increased the eradication rate nor reduced the occurrence of adverse events.

We aimed to compare the success rate, adverse drug events, and cost-effectiveness of tailoredThe diagnosis ofBetween the TT (n = 141) and PAM-B groups (n = 141),PAM-B therapy exhibits similar efficacy and improved cost-effectiveness compared to TT based on the results of DPO-PCR tests.www.clinicaltrials.gov identifier is NCT05002595.

The high security of optical phased array (OPA) signals is an important requirement for OPA-based optical wireless communication (OWC). We propose a method for improving the security of OPA-based OWC systems using optically injection-locked (OIL) semiconductor lasers. We theoretically demonstrate the amplitude and phase modulation of OIL-OPA elements by controlling the injection-locking parameters of the OIL lasers. When a Taylor window function is applied as the amplitude profile of the OPA transmitter, the sidelobe level decreases by 22 dB and the unsecured distance reduces 10 times compared to the case without the Taylor window function. In addition, the unsecured area factor becomes 0.8%.

Recently, the experimental discovery of high-$T_c$ superconductivity in compressed hydrides H$_3$S and LaH$_{10}$ at megabar pressures has triggered searches for various superconducting superhydrides. It was experimentally observed that thorium hydrides, ThH$_{10}$ and ThH$_9$, are stabilized at much lower pressures compared to LaH$_{10}$. Based on first-principles density-functional theory calculations, we reveal that the isolated Th frameworks of ThH$_{10}$ and ThH$_9$ have relatively more excess electrons in interstitial regions than the La framework of LaH$_{10}$. Such interstitial excess electrons easily participate in the formation of anionic H cage surrounding metal atom. The resulting Coulomb attraction between cationic Th atoms and anionic H cages is estimated to be stronger than the corresponding one of LaH$_{10}$, thereby giving rise to larger chemical precompressions in ThH$_{10}$ and ThH$_9$. Such a formation mechanism of H clathrates can also be applied to another experimentally synthesized superhydride CeH$_9$, confirming the experimental evidence that the chemical precompression in CeH$_9$ is larger than that in LaH$_{10}$. Our findings demonstrate that interstitial excess electrons in the isolated metal frameworks of high-pressure superhydrides play an important role in generating the chemical precompression of H clathrates.

The experimental realization of high-temperature superconductivity in compressed hydrides ${\mathrm{H}}_{3}\mathrm{S}$ and ${\mathrm{LaH}}_{10}$ under high pressures over 150 GPa has aroused great interest in reducing the stabilization pressure of superconducting hydrides. For cerium hydride ${\mathrm{CeH}}_{9}$ recently synthesized at $80--100$ GPa, our first-principles calculations reveal that the strongly hybridized electronic states of $\mathrm{Ce}\text{\ensuremath{-}}4f$ and $\mathrm{H}\text{\ensuremath{-}}1s$ orbitals produce the topologically nontrivial Dirac nodal lines around the Fermi energy ${E}_{F}$, which are protected by crystalline symmetries. By hole doping, ${E}_{F}$ shifts down toward the symmetry-driven van Hove singularity to increase the density of states, which in turn significantly raises a superconducting transition temperature ${T}_{c}$. We show that hole doping with ${\mathrm{Ce}}^{3+}$ ions can be very electronically miscible in ${\mathrm{CeH}}_{9}$ because both ${\mathrm{Ce}}^{3+}$ and Ce behave similarly as cations. Therefore, the interplay of crystalline symmetry, band topology, and hole doping contributes to enhance ${T}_{c}$ in compressed ${\mathrm{CeH}}_{9}$, which can also be demonstrated in another superconducting rare-earth hydride, ${\mathrm{LaH}}_{10}$.

Objective: Serum levels of pepsinogen (PG) are related to Helicobacter pylori-induced inflammation of the gastric mucosa. This study aimed to examine the influence of H. pylori eradication ...

We developed a method to generate optical complex signals based on optically injection-locked (OIL) semiconductor lasers and numerically evaluated their performance depending on the injection-locking parameters, injection ratio, and detuning frequency. We first determined the stable/unstable locking regions of the OIL system as a function of the injection-locking parameters through steady-state analysis. We then mapped the optical complex signal in both the stable injection-locking region and the complex signal plane. Based on the mapped relationship between the positions in the conventional injection-locking map and the complex signal plane, we theoretically evaluated the optical trajectories and constellation diagrams for the optical phase-shift keying signals and calculated the error-vector-magnitude with a data rate of 10 Gbaud/s using a time-domain calculation. We found that the complex signal performance could be improved using a higher injection ratio under a large negative detuning frequency.

Sedation, defined as the depressed level of consciousness, induced by drug administration, is widely used for gastrointestinal endoscopy to relieve a patient’s anxiety and discomfort. In addition, successful procedure is anticipated with control of unintended movements. Endoscopic sedation, however, cannot be free from the risk of serious adverse events, e.g., cardiopulmonary compromise. Therefore, principles on personnel, facility and equipment, as well as performance itself, should be followed to prevent unfavorable incidents. In this article, sedation guidelines for the Accreditation of Qualified Endoscopy Units, issued by the Korean Society of Gastrointestinal Endoscopy, are presented.

Activation of the ligand binding to substrate is a highly desirable, yet challenging reaction for biomolecular coating on the biomedical material surface. One advantage of this process is their modular construction on the surface as the biomolecular linkers, allowing for flexible design and detailed control of certain properties. In this work, we studied the binding properties of NH3 and HCOOH on Mg (0 0 0 1) surface and tried to understand the effect of alloy elements in the binding process. First principles within density functional theory (DFT) has been used to investigate the adsorption of NH3 and HCOOH molecules on Mg (0 0 0 1) and Zn-(Y-) doped surfaces. The electron redistribution, effect of alloy element and changes in the density of states of interaction systems are analyzed. Our results revealed that NH3 and HCOOH interact with the Mg (0 0 0 1) surface through dative bond with the adsorption energy (Eads) −0.70 and −0.64 eV, and the Zn/Y alloy element can improve the adsorption process which accompanied by charge-transfer between substrate and adsorbate. Calculated results of the nudged elastic band (NEB) show that the energy barrier of 0.14 eV need to be overcome for NH3 from the neighbor site to Y atom. Our findings provide insight for the binding mechanism of ligand on Mg and Mg-based alloy surfaces and also point out some directions for future experimental efforts.

Graphene-based two dimensional atomically thin van der Waals heterostructures show peculiar electronic feature such as energetically resolved Dirac ring. Using first-principles calculations, here we observe that there are two splitting Dirac cones in graphene/phosphorene/graphene trilayer heterostructure, which have not only the relatively large band gap opening as usual, but also possess both distinctly spatially and energetically resolved property. The underling mechanism can be attributed to the asymmetric quantum confinement-induced asymmetric charge distribution due to the presence of glide reflection of phosphorene, leading to different coupling strength between the two layers of graphene and phosphorene. As a result, the induced resolved Dirac rings have substantially different Dirac features such as Fermi velocity and asymmetric factor. Such unique features are absence in phosphorene/graphene bilayer heterostructure and the counterpart crystal. These findings provide new insights into the Dirac electric properties, and can be useful for future design of graphene-based trilayer heterostructure.

Lanthanum hydride (${\mathrm{LaH}}_{10}$) with a sodalitelike clathrate structure was experimentally synthesized to exhibit a near-room-temperature superconductivity under megabar pressures. Based on first-principles density-functional theory calculations, we reveal that the metal framework of La atoms has excess electrons at interstitial regions. Such anionic electrons are easily captured to form a stable clathrate structure of H cages. We thus propose that the charge transfer from La to H atoms is mostly driven by the electride property of the La framework. Furthermore, the interaction between La atom and H cage induces a delocalization of La $5p$ semicore states to hybridize with the H $1s$ state. Consequently, the bonding nature of ${\mathrm{LaH}}_{10}$ is characterized as a mixture of ionic and covalent bonding between La atom and H cage. Our findings demonstrate that anionic and semicore electrons play important roles in stabilizing clathrate H cages in ${\mathrm{LaH}}_{10}$, which can be broadly applicable to other compressed rare-earth hydrides with clathrate structures.

We aimed to compare the success rate, adverse drug events, and cost-effectiveness of tailored Helicobacter pylori eradication and modified bismuth-containing quadruple therapy. The diagnosis of H. pylori infection was randomly based on either rapid urease test (RUT) or dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) in 1:1 ratio. According to the presence of point mutations that cause clarithromycin resistance, patients in the tailored therapy (TT) group received standard triple therapy or classic bismuth quadruple therapy. Patients with positive RUT results received 40 mg pantoprazole, 1000 mg amoxicillin, 750 mg metronidazole, and 600 mg bismuth subcitrate twice daily for 14 days (PAM-B therapy). Between the TT (n = 141) and PAM-B groups (n = 141), H. pylori eradication rate did not differ significantly according to intention-to-treat (TT: 80.9% vs. PAM-B: 85.8%, P = 0.262), modified intention-to-treat (TT: 89.1% vs. PAM-B: 91.0%, P = 0.606), and per-protocol (TT: 89.0% vs. PAM-B: 93.5%, P = 0.198) analyses. The average cost for successful eradication was higher in the TT group than in the PAM-B group ($340.7 vs. $263.9 per patient). PAM-B therapy exhibits similar efficacy and improved cost-effectiveness compared to TT based on the results of DPO-PCR tests. www.clinicaltrials.gov identifier is NCT05002595

Recently, an alkaline earth hydride CaH6 having a sodalitelike clathrate structure has been experimentally synthesized at megabar pressures with a maximum T c of 215 K, comparable to that of a rare earth hydride LaH10. Here, based on first-principles calculations, we find that CaH6 exhibits a huge peak in the Eliashberg spectral function α 2 F around the low-frequency region of H-derived phonon modes, in contrast to LaH10 having a widely spreading spectrum of α 2 F over the whole frequencies of H-derived phonon modes. It is revealed that the huge peak of α 2 F in CaH6 is associated with an effective electron–phonon coupling (EPC) between low-frequency optical phonons and hybridized H 1s and Ca 3d states near the Fermi energy. As pressure increases, the strengthened H–H covalent bonding not only induces a hardening of optical phonon modes but also reduces the electron–phonon matrix elements related to the low-frequency optical modes, thereby leading to a lowering of the EPC constant. It is thus demonstrated that H-derived low-frequency phonon modes play an important role in the pressure-induced variation of T c in CaH6. Furthermore, unlike the presence of two distinct superconducting gaps in LaH10, CaH6 is found to exhibit a single isotropic superconducting gap.

In this study, the oscillation signal stabilization and spurious tone suppression of a directly modulated optoelectronic oscillator (DM-OEO) are simultaneously achieved by modulating a laser with a low-frequency radio frequency (RF) signal. The laser in the DM-OEO is modulated by a rectangular wave with a period inversely proportional to the frequency interval of the spurious tones and a duty cycle of 50%. The optical sidebands of the rectangular wave-modulated laser pulled the optical gain of the spurious tones of the DM-OEO, resulting in a spurious tone suppression and time stabilization in the DM-OEO signal. We achieve a 15 GHz DM-OEO with a 40.14 dB side-mode suppression ratio (SMSR) and 2.55 dB improvement in the oscillation power stability compared to that without RF modulation.

The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high-$$T_{\rm{c}}$$ T c superconductivity at high pressure. Recently, cerium hydride $$\hbox {CeH}_9$$ CeH 9 composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80–100 GPa, compared to other experimentally synthesized rare-earth hydrides such as $$\hbox {LaH}_{{10}}$$ LaH 10 and $$\hbox {YH}_6$$ YH 6 . Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of $$\hbox {CeH}_9$$ CeH 9 .

Symmetry principles play a critical role in formulating the fundamental laws of nature, with a large number of symmetry-protected topological states identified in recent studies of quantum materials. As compelling examples, massless Dirac fermions are jointly protected by the space inversion symmetry $P$ and time reversal symmetry $T$ supplemented by additional crystalline symmetry, while evolving into Weyl fermions when either $P$ or $T$ is broken. Here, based on first-principles calculations, we reveal that massless Dirac fermions are present in a layered FeSn crystal containing antiferromagnetically coupled ferromagnetic Fe kagome layers, where each of the $P$ and $T$ symmetries is individually broken but the combined $PT$ symmetry is preserved. These stable Dirac fermions protected by the combined $PT$ symmetry with additional non-symmorphic $S_{\rm{2z}}$ symmetry can be transformed to either massless/massive Weyl or massive Dirac fermions by breaking the $PT$ or $S_{\rm{2z}}$ symmetry. Our angle-resolved photoemission spectroscopy experiments indeed observed the Dirac states in the bulk and two-dimensional Weyl-like states at the surface. The present study substantially enriches our fundamental understanding of the intricate connections between symmetries and topologies of matter, especially with the spin degree of freedom playing a vital role., Comment: 6 pages, 4 figures

Nonmagnetic graphene-based van der Waals heterotrilayers exhibit peculiar electronic features such as energetically and/or spatially resolved Dirac rings/cones. Here, using first-principles calculations we study the effect of magnetic proximity effect and mirror symmetry of antiferromagnetic CrAs

Recently, two-dimensional layered electrides have emerged as a new class of materials which possess anionic electron layers in the interstitial spaces between cationic layers. Here, based on first-principles calculations, we discover a time-reversal-symmetry-breaking Weyl semimetal phase in a unique two-dimensional layered ferromagnetic (FM) electride Gd$_2$C. It is revealed that the crystal field mixes the interstitial electron states and Gd 5$d$ orbitals near the Fermi energy to form band inversions. Meanwhile, the FM order induces two spinful Weyl nodal lines (WNLs), which are converted into multiple pairs of Weyl nodes through spin-orbit coupling. Further, we not only identify Fermi-arc surface states connecting the Weyl nodes but also predict a large intrinsic anomalous Hall conductivity due to the Berry curvature produced by the gapped WNLs. Our findings demonstrate the existence of Weyl fermions in the room-temperature FM electride Gd$_2$C, therefore offering a new platform to investigate the intriguing interplay between electride materials and magnetic Weyl physics.

The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_{\rm{c}}$$\end{document}Tc superconductivity at high pressure. Recently, cerium hydride \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {CeH}_9$$\end{document}CeH9 composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80–100 GPa, compared to other experimentally synthesized rare-earth hydrides such as \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {LaH}_{{10}}$$\end{document}LaH10 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {YH}_6$$\end{document}YH6. Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {CeH}_9$$\end{document}CeH9.

To decrease gastric cancer-related mortality, the Korean National Cancer Screening Program provides biennial screening gastroscopy to all individuals aged40 years. However, a test-and-treat strategy ofIn this review, we present up-to-date results of endoscopic findings ofHere we propose approaches to

Background/Aims The aim of this in vivo animal study was to evaluate the effectiveness and safety of dedicated cold snare (DCS) compared with those of traditional snare (TS) for cold snare polypectomy (CSP). Methods A total of 36 diminutive (5 mm) and 36 small (9 mm) pseudolesions were made by electrocoagulation in the colons of mini-pigs. Results For the diminutive lesions, there were no significant differences in technical success rate, procedure time, or complete resection rate between the DCS and TS groups; the rate of uneven resection margin in the DCS group was significantly lower than that of the TS group. For small lesions, technical success rate and complete resection rate were significantly higher in the DCS group than in the TS group (100% [18/18] vs. 55.6% [10/18], p=0.003; 94.4% [17/18] vs. 40% [4/10], p=0.006). In addition, the procedure duration was significantly shorter, and the rate of uneven resection margin was significantly lower in the DCS group (28.5 sec vs. 66.0 sec, p=0.006; 11.1% [2/18] vs. 100% [10/10], p

Recently, the discovery of room-temperature superconductivity (SC) was experimentally realized in the fcc phase of ${\mathrm{LaH}}_{10}$ under megabar pressures. This SC of compressed ${\mathrm{LaH}}_{10}$ has been explained in terms of strong electron-phonon coupling (EPC), but the detailed nature of how the large EPC constant and high superconducting transition temperature ${T}_{\mathrm{c}}$ are attained has not yet been clearly identified. Based on the density-functional theory and the Migdal-Eliashberg formalism, we reveal the presence of two nodeless, anisotropic superconducting gaps on the Fermi surface (FS). Here, the small gap is mostly associated with the hybridized states of H $s$ and La $f$ orbitals on the three outer FS sheets, while the large gap arises mainly from the hybridized state of neighboring H $s$ or $p$ orbitals on the one inner FS sheet. Further, we find that compressed ${\mathrm{YH}}_{10}$ with the same sodalitelike clathrate structure has the two additional FS sheets, enhancing EPC constant and ${T}_{\mathrm{c}}$. It is thus demonstrated that the nature of room-temperature SC in compressed ${\mathrm{LaH}}_{10}$ and ${\mathrm{YH}}_{10}$ features the multiband pairing of hybridized electronic states with large EPC constants.

A lithium-doped magnesium hydride ${\mathrm{Li}}_{2}{\mathrm{MgH}}_{16}$ was recently reported [Y. Sun et al., Phys. Rev. Lett. 123, 097001 (2019)] to exhibit the highest ever predicted superconducting transition temperature ${T}_{\mathrm{c}}$ under high pressure. Based on first-principles density-functional theory calculations, we reveal that the Li dopants locating in the pyroclore lattice sites give rise to the excess electrons distributed outside Li atoms. Such loosely bound anionic electrons are easily captured to stabilize a clathrate structure consisting of H cages. This addition of anionic electrons to H cages enhances the H-derived electronic density of states at the Fermi level, thereby leading to a high-${T}_{\mathrm{c}}$ superconductivity. We thus propose that the electride nature of Li dopants is an essential ingredient in the charge transfer between Li dopants and H atoms. Our findings offer a deeper understanding of the underlying mechanism of charge transfer in ${\mathrm{Li}}_{2}{\mathrm{MgH}}_{16}$ at high pressure.

Recently, the discovery of room-temperature superconductivity (SC) was experimentally realized in the fcc phase of LaH$_{10}$ under megabar pressure. Specifically, the isotope effect of $T_{\rm c}$ was measured by the replacement of hydrogen (H) with deuterium (D), demonstrating a driving role of phonons in the observed room-temperature SC. Herein, based on the first-principles calculations within the harmonic approximation, we reveal that (i) the identical electron-phonon coupling constants of fcc LaH$_{10}$ and LaD$_{10}$ decrease monotonously with increasing pressure and (ii) the isotope effect of $T_{\rm c}$ is nearly proportional to $M^{-{\alpha}}$ ($M$: ionic mass) with ${\alpha}$ ${\approx}$ 0.465, irrespective of pressure. The predicted value of ${\alpha}$ agrees well with the experimental one (${\alpha}=0.46$) measured at around 150 GPa. Thus, our findings provide a theoretical confirmation of the conventional electron-phonon coupling mechanism in a newly discovered room-temperature superconductor of compressed LaH$_{10}$., Comment: 7 pages, 5 figures

Background/Aims: The eradication rate of the first-line triple therapy (a proton pump inhibitor, clarithromycin, and amoxicillin) for Helicobacter pylori infection has gradually decreased in Korea. We evaluated whether clinical parameters, clar ithromycin resistance, and CYP2C19 genotype can affect the eradication failure. Methods: A total of 203 patients with H. pylori-positive chronic gastritis were consecutively enrolled. They received clarithromycin-based triple therapy for 7 days. A clarithromycin resistance test was performed by detection of A2142G and A2143G point mutations in H. pylori 23S rRNA. The CYP2C19 genotype was ex amined for polymorphism G681A of exon 5 and G636A of exon 4 by polymerase chain reaction with restriction fragment length polymorphism. Eradication was assessed by a 13C-urea breath test 4 weeks after treatment. Results: Of 203 patients, 190 completed the study. The eradication rate was 64.0% according to intention-to-treat analysis and 68.4% by per-protocol analysis. CY P2C19 genotypes were identified as follows: 75 poor metabolizers, 75 intermediate metabolizers, and 40 rapid metabolizers. Nonetheless, this polymorphism was not significantly associated with eradication failure (p = 0.682). Clarithromycin resistance was detected in 33/190 patients (17.4%), and their eradication rate was zero. Clarithromycin resistance (odds ratio [OR], 19.13; 95% confidence interval [CI], 9.35 to 35.09) and female gender (OR, 1.73; 95% CI, 1.15 to 4.25) were signifi cantly associated with eradication failure. The other clinical parameters such as age, cigarette smoking, alcohol intake, the body mass index, hypertension, and diabetes were not significantly associated with eradication. Conclusions: Clarithromycin resistance and female gender are factors affecting H. pylori eradication failure in patients with chronic gastritis.

Objective Limited evidence is available on rebleeding due to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced enteropathy. Previous studies have primarily analyzed endoscopic findings. Therefore, there is a need to evaluate their clinical implications for patients. This study aimed to evaluate the rebleeding rate and its related risk factors in patients with NSAIDs-induced enteropathy. Methods Of 402 patients with obscure gastrointestinal bleeding who were evaluated with capsule endoscopy, 49 were diagnosed with NSAIDs-induced enteropathy. The clinical characteristics of the patients were retrospectively analyzed. The Charlson comorbidity index was used to stratify the comorbidities. For patients who used additional drugs that influenced their tendency to bleeding, the odds ratio was calculated and used for a quantitative comparison. Results The rebleeding rate in patients with NSAIDs-induced enteropathy was 20.4%, within a mean duration of 23.4 months. Age ≥65 years (hazard ratio [HR] 8.628, 95% confidence interval [CI] 1.152-64.625), no additional use of mucoprotective agents (HR 11.712, 95% CI 1.278-76.098) and the continuation of NSAIDs after the first bleeding episode (HR 9.861, 95% CI 1.395-98.344) were independently related to rebleeding due to NSAIDs-induced enteropathy. The underlying comorbidities, drug-related rebleeding risk scores and therapeutic use of proton pump inhibitors were not significantly different (P = 0.209, 0.212 and 0.720, respectively). Conclusions Approximately one-fifth of patients with NSAIDs-induced enteropathy showed rebleeding within 2 years. A careful long-term follow-up should be offered to elderly patients with NSAIDs-induced enteropathy who need continuous NSAID treatment without the additional use of mucoprotective medications.