Graphene-Based Analog of Single-Slit Electron Diffraction.

This work reports the experimental demonstration of single-slit diffraction exhibited by electrons propagating in encapsulated graphene with an effective de Broglie wavelength corresponding to their attributes as massless Dirac fermions. Nanometer-scale device designs were implemented to fabricate a single-slit followed by five detector paths. Predictive calculations were also utilized to readily understand the observations reported. These calculations required the modeling of wave propagation in ideal case scenarios of the reported device designs to more accurately describe the observed single-slit phenomenon. This experiment was performed at room temperature and 190 K, where data from the latter highlighted the exaggerated asymmetry between electrons and holes, recently ascribed to slightly different Fermi velocities near the K point. This observation and device concept may be used for building diffraction switches with versatile applicability.

Unprecedented random lasing in 2D organolead halide single-crystalline perovskite microrods.

Three-dimensional organic-inorganic hybrid halide perovskites have been demonstrated as great materials for applications in optoelectronics and photonics. However, their inherent instabilities in the presence of moisture, light, and heat may hinder their commercialization. Alternatively, emerging two-dimensional (2D) organic-inorganic hybrid perovskites have recently attracted increasing attention owing to their great environmental stability and inherent natural quantum-well structure. In this work, we have synthesized a high-quality long-chain organic diammonium spacer assisted 2D hybrid perovskite FA-(N-MPDA)PbBr4 (FA = formamidinium and N-MPDA = N-methylpropane-1,3-diammonium) by the slow evaporation at constant temperature method. The millimeter-sized single-crystalline microrods demonstrate low threshold random lasing behavior at room temperature. The single-crystalline 2D hybrid perovskite random laser achieved a very narrow linewidth (∼0.1 nm) with a low threshold (∼0.5 µJ cm-2) and a high quality factor (∼5350). Furthermore, the 2D hybrid microrod laser shows stable lasing emission with no measurable degradation after at least 2 h under continuous illumination, which substantially proves the stability of 2D perovskites. Our results demonstrate the promise of 2D organic-inorganic microrod-shaped perovskites and provide an important step toward the realization of high-performance optoelectronic devices.

Round Cell Tumors: Classification and Immunohistochemistry.

Round cell tumors as the name suggest are comprised round cells with increased nuclear-cytoplasmic ratio. This group of tumor includes entities such as peripheral neuroectodermal tumor, rhabdomyosarcoma, synovial sarcoma, non-Hodgkin's lymphoma, neuroblastoma, hepatoblastoma, Wilms' tumor, and desmoplastic small round cell tumor. These round cells tumors are characterized by typical histological pattern, immunohistochemical, and electron microscopic features that can help in differential diagnosis. The present article describes the classification and explains the histopathology and immunohistochemistry of some important round cell tumors.

Evaluation of child preference for dentist attire and usage of camouflage syringe in reduction of anxiety.

OBJECTIVES: The aim of this study is to evaluate the child preference for dentist attire and camouflage versus conventional syringe in reduction of anxiety. MATERIALS AND METHODS: A total of 600 children aged 6-14 years were made to look at a set of six photos of an individual dressed with different colored apron of pink, green, blue, white colors, formal dress, and cartoon character along with conventional syringe and camouflage syringe with a toy-like appearance to permit injection of local anesthesia. Children's anxiety level during injections and with colored coat was assessed and recorded using the Modified Child Dental Anxiety Scale faces version. STATISTICAL ANALYSIS USED: SPSS statistical software version 21 and using Chi-square test. RESULTS: Among age group of 6-8 years, 65.33% selected colorful apron, while other age groups 9-10, 11-12 years, and 13-14 years selected 47.34%, 57.34%, and 50.67% white coat, respectively (P < 0.05). For syringe, 78% of younger age group (6-10 years) preferred camouflage syringe, whereas 71% of older age group (11-14 years) preferred conventional syringe. Anxiety level of all children for syringe was more compared to that of white coat. CONCLUSION: Younger children prefer colorful attire of dentist and camouflage syringe over conventional compared to older one.

Comparative Evaluation of Fracture Resistance of Different Post Systems.

AIM: The study was done to evaluate the fracture resistance of carbon, glass fiber, and zirconia posts. MATERIALS AND METHODS: Forty-five human premolars indicated for orthodontic extraction were subjected to root canal treatment and obturated with gutta-percha. All the teeth were decoronated and mounted in acrylic block. Then, teeth were equally divided into three groups: (a) carbon, (b) glass fiber, and (c) zirconia post group. Post space was prepared and particular post was cemented in post space. Core buildup was made with composite. A compressive load was applied using universal testing machine and fracture force was measured in MPa. The data were tabulated, and statistical evaluation was done using statistical software IBM SPSS Statistics for Windows, version 21.0., IBM Corp., Armonk, NY, USA, using one-way analysis of variance for analysis of difference and Bonferroni post hoc test. RESULTS: Zirconia endodontic post had good fracture resistance (489.2 MPa) when compared with carbon (258.4 MPa) and glass fiber-reinforced post (348.7 MPa). Fracture resistance was statistically significant between test groups P>0.001. CONCLUSION: The present study concluded that zirconia had good fracture resistance compared to glass fiber and carbon posts.