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Copyright of Egyptian Journal of Histology is the property of Egyptian Journal of Histology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Laparoscopic single anastomosis gastric bypass (SAGB) is increasingly performed for morbidly obese patients. Aim of Work: This pilot study aims primarily at evaluating the incidence of bile gastritis after SAGB. The occurrence of reflux oesophagitis and reflux symptoms were also assessed. Patients and Methods: This study included 20 patients having no reflux symptoms. All patients underwent a SAGB as a primary bariatric procedure by a single surgeon. Patients included consented to have an upper GI endoscopy done at 6 months postoperatively. Gastric aspirate was sent for bilirubin level assessment. Gastric and esophageal biopsies were submitted for histopathology and campylobacter-like organism (CLO) test. Results: In our study, the rate of bile gastritis was 30%. In 18 patients, the level of bilirubin in gastric aspirate seems to be related to the degree of mucosal inflammation. The remaining two patients had microscopic moderate to severe gastritis with normal aspirate bilirubin level. Two patients with bilirubin level in aspirate more than 20 mg/dl had severe oesophagitis, gastritis with erosions, and metaplasia. Relationship between bilirubin level and histopathological findings of gastric biopsy examination was statistically significant with a P value of 0.001. Conclusion: The incidence of bile gastritis in this cohort is higher than reported in the literature, and this may be worrying. The correlation between endoscopic findings and patients' symptoms is poor. Bilirubin level and pH in aspirate might be useful tools to confirm alkaline reflux. Its level might help to choose candidates for revision surgery after SAGB. This needs further validation with larger sample size. [ABSTRACT FROM AUTHOR]

The topology of Weyl semimetals requires the existence of unique surface states. Surface states have been visualized in spectroscopy measurements, but their connection to the topological character of the material remains largely unexplored. 1T'-MoTe2, presents a unique opportunity to study this connection. This material undergoes a phase transition at 240 K that changes the structure from orthorhombic (putative Weyl semimetal) to monoclinic (trivial metal), while largely maintaining its bulk electronic structure. Here, we show from temperature-dependent quasiparticle interference measurements that this structural transition also acts as a topological switch for surface states in 1T'-MoTe2. At low temperature, we observe strong quasiparticle scattering, consistent with theoretical predictions and photoemission measurements for the surface states in this material. In contrast, measurements performed at room temperature show the complete absence of the scattering wavevectors associated with the trivial surface states. These distinct quasiparticle scattering behaviors show that 1T'-MoTe2 is ideal for separating topological and trivial electronic phenomena via temperature-dependent measurements. Weyl semimetals: switching off topology A temperature-induced structural phase transition can provide insight into the effect of Fermi arcs on the properties of Weyl semimetals. Weyl semimetals are topological materials at the surface of which Weyl points—the points at which electron and hole pockets touch—are connected in pairs by Fermi arc surface states. Probing the topological nature of the surface states has so far proven difficult, and a connection with the band structure of the material is complex to establish. An international team of researchers led by Abhay Pasupathy at Columbia University demonstrated, by combining experiments and theory, that the Weyl semimetal MoTe2 undergoes a temperature-driven structural phase transition that switches off the Weyl behavior. This makes it possible to systematically compare the electronic properties of the trivial and topological states. [ABSTRACT FROM AUTHOR]

The authors show that the tunability of a femtosecond optical parametric amplifier combined with its high-repetition rate and short pulses provide a powerful tool for an alternate approach to conventional nonresonant band mapping by two-photon photoemission (2PPE). The authors demonstrate this 2PPE mapping via use of two model systems, i.e., the pair of sp surface and image states on flat Cu(111) and vicinal Cu(775) surfaces, over a photon energy range of 3.9-4.6 eV by making use of direct resonant band-to-band electronic transitions. Since the experimental excitation of the Cu image state from the surface state is comparable in time to the electron-electron equilibration time, the authors measure sharp resonant features in the electron energy distributions. In this approach, the authors track these resonant electronic transitions using 2PPE by varying the photon energy so as to achieve resonant excitation at each value of photoelectron emission angle over a large wavelength range on both types of surfaces. In addition, the authors explore the range of photon energies and optical intensities which may be used for this approach. The repetition rate of this laser was sufficient to yield a good signal-to-noise ratio while maintaining pump pulse intensities at levels that were low enough to prevent significant photon-induced space-charge broadening and electron-kinetic-energy shifting, even for photon energies close to the work function of the sample. [ABSTRACT FROM AUTHOR]