The microstructure and microtexture of zirconium oxide films studied by transmission electron backscatter diffraction and automated crystal orientation mapping with transmission electron microscopy

A detailed characterization of nanostructured thin zirconium oxide films formed during aqueous corrosion of a nuclear-grade zirconium alloy (Zircaloy-4) has been carried out by means of two novel, ultra-high-spatial-resolution grain mapping techniques, namely automated crystal orientation mapping in the transmission electron microscope (TEM) and transmission electron backscatter diffraction (t-EBSD). While the former provided excellent spatial resolution with the ability to identify tetragonal ZrO<sub>2</sub> grains as small as ∼5 nm, the superior angular resolution and unambiguous indexing with t-EBSD enabled verification of the TEM observations. Both techniques revealed that in a stress-free condition (TEM foil prepared by focused ion beam milling), the oxide consists mainly of well-oriented columnar monoclinic grains with a high fraction of transformation twin boundaries, which indicates that the transformation from tetragonal to monoclinic ZrO<sub>2</sub> is a continuous process, and that a significant fraction of the columnar grains transformed from stress-stabilized tetragonal grains with (0 0 1) planes parallel to the metal–oxide interface. The TEM analysis also revealed a small fraction of size-stabilized, equiaxed tetragonal grains throughout the oxide. Those grains were found to show significant misalignment from the expected (0 0 1) growth direction, which explains the limited growth of those grains. The observations are discussed in the context of providing new insights into corrosion mechanisms of zirconium alloys, which is of particular importance for improving service life of fuel assemblies used in water-cooled reactors

Micronuclei Comparison in Lichen Planus and Oral Lichenoid Responses

BACKGROUND AND OBJECTIVE: Lichen planus is a mucocutaneous chronic inflammatory disease with unknown etiology. Malignant potential of oral lichen planus (OLP) and lichenoid reactions (OLR) are controversial. Since micronucleus frequency of cells is representative of risk of malignancy, the aim of present study was to evaluate micronucleus frequency in these lesions. METHODS: In this cross-sectional study, study group consisted of 20 OLP and 20 OLR which clinically and histopathologically had been confirmed and 20 healthy individuals without oral lesions and systemic disease who presented in oral medicine department of Babol dental college. After receiving written consent, smears were prepared from lesion site at buccal mucosa by cytobrush and were stained at laboratory using Papanicolaou stain. In each slide 500 cells were assessed under light microscope at 400X magnification; mean number of micronucleated cells and mean total numbers of micronuclei were calculated. FINDINGS: Mean number of micronucleated cells in OLP, OLR and normal mucosa were 5.20±3.73, 5.65±3.66 and 0.95±1.19 and number of micronuclei were 6.75±4.94, 8±4.66 and 1.30±1.72 respectively. Mean number of micronucleated cells and number of micronuclei were significantly greater in OLP and OLR than normal mucosa (p<0.001) but there were no significant differences between OLP and OLR (p=0.67 and p=0.36 respectively). There were no significant differences in mean number of micronucleated cells between reticular and erosive subtypes of OLP and also OLR (p=0.96). There were also no significant differences in mean number of micronuclei between these subtypes (p=0.96 and p=0.93 respectively). CONCLUSION: The results of this study indicated that significant increase in micronucleus frequency of OLP and OLR are probably indicative of higher risk of malignancy in these lesions

Correlation between Visual Acuity and Optical Coherence Tomography-Measured Retinal Thickness in Diabetic Macular Edema

Background and Objective: Diabetic macular edema (DME) is one of the common complications of diabetes which significantly accounts for preventable visual impairment and blindness. Central macular thickness (CMT) is a feature found in DME patients. This study aims to determine the relationship between optical coherence tomography (OCT)-measured CMT and visual acuity (VA) in patients with DME before and after intravitreal injection of bevacizumab. Methods: This cross-sectional study was conducted on 100 patients with diabetic macular edema with involvement of both eyes referred to the Ophthalmology Department of Rouhani Hospital in Babol who underwent intravitreal injection of Bevacizumab. VA (measured by Snellen chart), CMT (measured by OCT), clinical and paraclinical factors (including the duration of diabetes, glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), hypertension, and smoking history data) were evaluated and compared among all patients just before and 45 days after Bevacizumab injection. Findings: Before the injection of Bevacizumab in 200 eyes, the mean value of VA (letter score) and mean value of CMT (µm) were 36.83±12.73 and 425.48±85.18 µm, respectively (p<0.001, 95% CI=12.5 – 17.5 and 95% CI=-71.5 – -55.5, respectively). 45 days after Bevacizumab injection, the mean value of absolute VA changes was 15.24±10.16, and the mean value of absolute CMT changes was -67.83±43.08 µm (coefficient=-0.18, 95% CI=-0.39 – 0.05). Conclusion: Although VA was correlated moderately with CMT and the polynomial regression model enhanced the predictive ability, it remains fully obvious that CMT and clinical factors could play an essential role as VA surrogates

The Effect of Mesalazine on Pain Management in Patients with Diarrhea-Predominant Irritable Bowel Syndrome

Background and Objective: Irritable bowel syndrome is one of the common gastrointestinal complaints that is often resistant to standard treatment. Since mesalazine reduces abdominal pain and diarrhea through its anti-inflammatory effects, this study was conducted to investigate the effect of mesalazine on pain management in patients with diarrhea-predominant irritable bowel syndrome (IBS-D). Methods: This case-control study was conducted among 100 patients diagnosed with diarrhea-predominant irritable bowel syndrome referred to Ayatollah Rouhani Hospital in Babol. Patients were randomly divided into two groups of 50, receiving standard treatment (amitriptyline 25 mg) and a group that received mesalazine at a dose of 500 mg for 4 weeks three times a day in addition to standard treatment. Subjects were examined and compared in terms of pain intensity and frequency of discharge and recovery. Findings: The intensity of pain after treatment in the case group was lower than before treatment (4.66±2.29 vs. 7.80±2.01) (p=0.004). Out of 50 patients, 38 people (76.0%) in the case group and only 20 people (40%) in the control group recovered (p<0.001). In the case group, the number of bowel movements after treatment (2.20±0.92) was significantly less than before (4.92±0.92) (p<0.001). In the control group, the number of bowel movements showed a statistically significant difference before and after treatment (5.22±1.07 vs. 2.50±1.19) (p<0.001). Conclusion: Based on the results of this study, mesalazine is significantly effective in reducing the intensity of pain caused by irritable bowel syndrome. However, there was no difference in the number of excretions

Laboratory Evaluation of Color Change and Surface Roughness of White Spot Lesions Treated with Resin Infiltration and Fluoride Therapy

Background and Objective: Two non-invasive treatment methods for treating white spot lesions (WSLs) include resin infiltration and fluoride therapy. Contradictions have been raised regarding the color change and surface roughness of the lesions based on these methods. Therefore, this study was conducted to investigate the color change and surface roughness of white spot lesions after treatment with resin infiltration and fluoride therapy. Methods: In this laboratory study, 40 buccal and lingual sections were prepared from 20 extracted healthy premolar teeth. 10 samples were considered as the control group, and in the other 30 samples, decayed lesions were created artificially. White spot lesions were randomly prepared in three groups without treatment, 0.05% sodium fluoride solution and resin infiltration (n=10). Then, the rate of color change and surface roughness of the samples after being placed in black tea and also after brushing were measured and compared using spectrophotometer and profilometer. Findings: The surface roughness of samples in resin infiltration, intact enamel and fluoride groups were 163.46±64.67, 259.6±43.12 and 293.92±41.36 micrometers, respectively (p<0.001). Before placing in tea and after brushing, no significant difference was observed in the color of the samples, but after staining, the color change in WSL (9.14±5.85), fluoride (17.40±4.13) and resin infiltration (12.13±4.88) groups was significant (p=0.004); the fluoride group showed significantly more color change compared to the WSL group (p=0.003), but the difference between the other groups was not significant. Conclusion: The results of this study show that if the resin infiltration method is used in the treatment of white spot lesions, less surface roughness and color change is observed compared to fluoride therapy

Resolving physical interactions between bacteria and nanotopographies with focused ion beam scanning electron microscopy

To robustly assess the antibacterial mechanisms of nanotopographies, it is critical to analyze the bacteria-nanotopography adhesion interface. Here, we utilize focused ion beam milling combined with scanning electron microscopy to generate three-dimensional reconstructions of Staphylococcus aureus or Escherichia coli interacting with nanotopographies. For the first time, 3D morphometric analysis has been exploited to quantify the intrinsic contact area between each nanostructure and the bacterial envelope, providing an objective framework from which to derive the possible antibacterial mechanisms of synthetic nanotopographies. Surfaces with nanostructure densities between 36 and 58 per μm(2) and tip diameters between 27 and 50 nm mediated envelope deformation and penetration, while surfaces with higher nanostructure densities (137 per μm(2)) induced envelope penetration and mechanical rupture, leading to marked reductions in cell volume due to cytosolic leakage. On nanotopographies with densities of 8 per μm(2) and tip diameters greater than 100 nm, bacteria predominantly adhered between nanostructures, resulting in cell impedance

Electronic properties of graphene encapsulated with different two-dimensional atomic crystals.

Hexagonal boron nitride is the only substrate that has so far allowed graphene devices exhibiting micrometer-scale ballistic transport. Can other atomically flat crystals be used as substrates for making quality graphene heterostructures? Here we report on our search for alternative substrates. The devices fabricated by encapsulating graphene with molybdenum or tungsten disulfides and hBN are found to exhibit consistently high carrier mobilities of about 60 000 cm(2) V(-1) s(-1). In contrast, encapsulation with atomically flat layered oxides such as mica, bismuth strontium calcium copper oxide, and vanadium pentoxide results in exceptionally low quality of graphene devices with mobilities of ∼1000 cm(2) V(-1) s(-1). We attribute the difference mainly to self-cleansing that takes place at interfaces between graphene, hBN, and transition metal dichalcogenides. Surface contamination assembles into large pockets allowing the rest of the interface to become atomically clean. The cleansing process does not occur for graphene on atomically flat oxide substrates.This work was supported by the European Research Council, Graphene Flagship, Engineering and Physical Sciences Research Council (UK), the Royal Society, US Office of Naval Research, US Air Force Office of Scientific Research, US Army Research Office

Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic Crystals

Hexagonal boron nitride is the only substrate that has so far allowed graphene devices exhibiting micron-scale ballistic transport. Can other atomically flat crystals be used as substrates for making quality graphene heterostructures? Here we report on our search for alternative substrates. The devices fabricated by encapsulating graphene with molybdenum or tungsten disulphides and hBN are found to exhibit consistently high carrier mobilities of about 60,000 cm$^{2}$V$^{-1}$s$^{-1}$. In contrast, encapsulation with atomically flat layered oxides such as mica, bismuth strontium calcium copper oxide and vanadium pentoxide results in exceptionally low quality of graphene devices with mobilities of ~ 1,000 cm$^{2}$ V$^{-1}$s$^{-1}$. We attribute the difference mainly to self-cleansing that takes place at interfaces between graphene, hBN and transition metal dichalcogenides. Surface contamination assembles into large pockets allowing the rest of the interface to become atomically clean. The cleansing process does not occur for graphene on atomically flat oxide substrates.Comment: 19 pages, 11 figures, 1 table including Supporting Informatio