Search

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]

Density functional theory (DFT) has been immensely successful in its ability to predict physical properties and, in particular, structures of condensed matter systems. Here, however, we show that DFT qualitatively fails to predict the dimerized structural phase for a monatomic Co wire that is self-assembled on a vicinal (i.e. stepped) Cu(111) substrate. To elucidate the nature of this failure, we compute the energetics of a Co chain on a Cu surface, step, and notch and embedded in bulk. The results demonstrate that increasing Co coordination extinguishes the dimerization, indicating that the failure of DFT for Co on the Cu step arises from excessive hybridization, which both weakens the ferromagnetic correlations that drive the dimerization and increases the bonding that opposes dimerization. Additionally, we show that including local interactions via DFT + U or DFT + dynamical mean field theory (DMFT) does not restore the dimerization for the stepped-substrate-supported wire, although the Co wire does dimerize in DFT + DMFT for the isolated vacuum case. This system can serve as a benchmark for future electronic structure methods. [ABSTRACT FROM AUTHOR]

Using low-temperature scanning tunneling microscopy, we demonstrate a one-dimensional system that undergoes a charge-density-wave (CDW) instability on a metallic substrate. For our measurements we utilize a self-assembled monatomic chain of Co atoms aligned by the steps on a vicinal Cu(111) surface. We assign the measured CDW instability to ferromagnetic interactions along the chain. We show that though the linear arrayed dimers are not electronically isolated, they are magnetically independent, and hence can potentially serve as a binary spin-memory system. [ABSTRACT FROM AUTHOR]

AbstractObjectiveMaterials and MethodsResultsDiscussion and conclusionThis research assesses renoprotective effects of saracatinib (Src) in diabetic nephropathy (DN) and the potential underlying processes.Rats were divided into: control, DN, DN + Met + Los, DN + Met + Src, and DN + Met + Los + Src. Rats’ ABP, urinary albumin, urinary nephrin, and creatinine clearance were assessed. Blood samples were collected for measuring glycaemic state parameters, renal functions, oxidative stress markers, inflammatory mediators, aldosterone, and lipid profile. Kidneys were extracted for KIM-1 and nephrin gene expression, H&E, Masson’s trichrome staining, and immunohistochemical assessment.Significant increases in ABP, urinary albumin and nephrin, glycaemic measurements, urea, creatinine, aldosterone, inflammatory cytokines, MDA, lipids, renal fibrosis, H scores of VEGF and TGF-β, and renal KIM-1 expression were related to DN. However, there was a significant decrease in creatinine clearance, GSH, and nephrin expression in DN group compared with control group.The combination of metformin (Met), losartan (Los), and Src repaired DN alterations. Adding Src to Met and Los is superior to using them alone. [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]

We directly measure the electronic structure of twisted graphene/MoS2 van der Waals heterostructures, in which both graphene and MoS2 are monolayers. We use cathode lens microscopy and microprobe angle-resolved photoemission spectroscopy measurements to image the surface, determine twist angle, and map the electronic structure of these artificial heterostructures. For monolayer graphene on monolayer MoS2, the resulting band structure reveals the absence of hybridization between the graphene and MoS2 electronic states. Further, the graphene-derived electronic structure in the heterostructures remains essentially intact, irrespective of the twist angle between the two materials. In contrast, however, the electronic structure associated with the MoS2 layer is found to be twist-angle dependent; in particular, the relative difference in the energy of the valence band maximum at Г and K of the MoS2 layer varies from approximately 0 to 0.2 eV. Our results suggest that monolayer MoS2 within the heterostructure becomes predominantly an indirect band-gap system for all twist angles except in the proximity of 30°. This result enables potential band-gap engineering in van der Waals heterostructures comprised of monolayer structures. [ABSTRACT FROM AUTHOR]

We report angle-resolved photoemission spectroscopic measurements of the evolution of the thicknessdependent electronic band structure of the atomically heavy two-dimensional layered dichalcogenide, tungsten diselenide (WSe2). Our data, taken on mechanically exfoliated WSe2 single crystals, provide direct evidence for shifting of the valence-band maximum from Γ (multilayer WSe2) to K (single-layer WSe2). Further, our measurements also set a lower bound on the energy of the direct band gap and provide direct measurement of the hole effective mass. [ABSTRACT FROM AUTHOR]

We report on the evolution of the thickness-dependent electronic band structure of the two-dimensional layered-dichalcogenide molybdenum disulfide (MoS2). Micrometer-scale angle-resolved photoemission spectroscopy of mechanically exfoliated and chemical-vapor-deposition-grown crystals provides direct evidence for the shifting of the valence band maximum from ̄Γ to ̄K, for the case of MoS2 having more than one layer, to the case of single-layer MoS2, as predicted by density functional theory. This evolution of the electronic structure from bulk to few-layer to monolayer MoS2 had earlier been predicted to arise from quantum confinement. Furthermore, one of the consequences of this progression in the electronic structure is the dramatic increase in the hole effective mass, in going from bulk to monolayer MoS2 at its Brillouin zone center, which is known as the cause for the decreased carrier mobility of the monolayer form compared to that of bulk MoS2. [ABSTRACT FROM AUTHOR]

We report the directly measured electronic structure of exfoliated monolayer molybdenum disulfide (MoS2) using micrometer-scale angle-resolved photoemission spectroscopy. Measurements of both suspended and supported monolayer MoS2 elucidate the effects of interaction with a substrate. A suggested relaxation of the in-plane lattice constant is found for both suspended and supported monolayer MoS2 crystals. For suspended MoS2, a careful investigation of the measured uppermost valence band gives an effective mass at Γ and K of 2.00m0 and 0.43m0, respectively. We also measure an increase in the band linewidth from the midpoint of ΓK to the vicinity of K and briefly discuss its possible origin. [ABSTRACT FROM AUTHOR]