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Successful recognition of a dynamically stable carbonitride structure revealed that unlike other planar layered structures in the case of g-C3N4 the stable configurations are distorted [J. Wang et al., Chem. Mater., 2017, 29(7), 2694–2707, DOI: https://doi.org/10.1021/acs.chemmater.6b02969.]. This generates interest in a detailed study of the possibilities of controlling the structure and its properties both in its pristine and heterostructure forms. Here, we present the results of the investigation of dynamically stable bulk and monolayer g-C3N4, and a g-C3N4/MoS2 heterostructure. The bulk g-C3N4 was found to be an indirect band gap semiconductor exhibiting an indirect-to-direct band gap transition upon dimensionality reduction. In the case of the heterostructure, the analysis of partial density of states shows a charge transfer from nitrogen ions in g-C3N4 to the MoS2 layer. The Raman spectra of bulk g-C3N4 are discussed in detail, and the changes occurring in the spectra upon the transition to the monolayer form and in the g-C3N4/MoS2 heterostructure are demonstrated. It was found that the characteristic features of such an atomic transition can be seen in the region below 300 cm−1 and between 700 and 800 cm−1. [ABSTRACT FROM AUTHOR]

We have reported the density functional theory investigations on the monolayered, 2 layered and bulk MoSi2N4 in three structural modifications called α1 [Y.-L. Hong, et al., Chemical Vapor Deposition of Layered Two-Dimensional MoSi2N4 Materials, Science, 2020, 369(6504), 670–674, DOI: 10.1126/science.abb7023], α2 and α3 [Y. Yin, Q. Gong, M. Yi and W. Guo, Emerging Versatile Two-Dimensional MoSi2N4 Family, Adv. Funct. Mater., 2023, 2214050, DOI: 10.1002/adfm.202214050]. We showed that in the case of monolayers the difference in total energies is less than 0.1 eV between α1 and α3 phases, and less than 0.2 eV between α1 and α2 geometries. The most energetically favorable layer stacking for the bulk structures of each phase was investigated. All considered modifications are dynamically stable from a single layer to a bulk structure in energetically favorable stacking. Raman spectra for the monolayered, 2 layered and bulk structures were simulated and the vibrational analysis was performed. The main difference in the obtained spectra is associated with the position of the strongest band which depends on the Mo–N bond length. According to the obtained data, we can conclude that the Raman line at 348 cm−1 in the experimental spectra of MoSi2N4 can have more complex explanation than just Γ-point Raman-active vibration as was discussed before in [Y.-L. Hong, et al., Chemical Vapor Deposition of Layered Two-Dimensional MoSi2N4 Materials, Science, 2020, 369(6504), 670–674, DOI: 10.1126/science.abb7023]. [ABSTRACT FROM AUTHOR]

The structural and physicochemical properties of the MoSe2/PTCDA heterostructure, which consists of two-dimensional inorganic and molecular organic semiconductors, have been studied theoretically. Features of change in the electronic properties of the PTCDA monomolecular layer on the MoSe2 surface have been described by density functional theory. The quantitative analysis of charge transfer between the heterostructure components has explained the features of coupling between the layers. The study of the optical characteristics of the heterostructure has revealed the enhancement of the absorption spectrum in the infrared range. Consequently, MoSe2/PTCDA heterostructures are promising for applications in electronics, optoelectronics, and materials for the utilization of solar energy. [ABSTRACT FROM AUTHOR]

The structural and physicochemical properties of the MoSe2/PTCDA heterostructure, which consists of two-dimensional inorganic and molecular organic semiconductors, have been studied theoretically. Features of change in the electronic properties of the PTCDA monomolecular layer on the MoSe2 surface have been described by density functional theory. The quantitative analysis of charge transfer between the heterostructure components has explained the features of coupling between the layers. The study of the optical characteristics of the heterostructure has revealed the enhancement of the absorption spectrum in the infrared range. Consequently, MoSe2/PTCDA heterostructures are promising for applications in electronics, optoelectronics, and materials for the utilization of solar energy. [ABSTRACT FROM AUTHOR]

A novel quasi-two-dimensional monolayer structure with orthorhombic symmetry based on cobalt carbide, o-CoC, has been considered. This structure supplements a recently discovered family of quasi-two-dimensional compounds based on transition metals. The dynamic stability of a monolayer has been demonstrated. Its mechanical and electronic characteristics have been studied. [ABSTRACT FROM AUTHOR]

The structure and properties of high-pressure phases of iron nitrides Fe7N3 in the pressure range of 50-150 GPa have been studied with ab initio calculations within the electron density functional theory. A new phase Amm2-Fe7N3, which is the most energetically favorable in the pressure range of 43-128 GPa, has been found using the USPEX (Universal Structure Predictor: Evolutionary Xtallography) algorithms. It has been thermodynamically shown that another high-pressure phase β-Fe7N3 is isostructural to a similar phase of iron carbide. The elastic properties have been calculated for all modifications ε-, β-, and Amm2-Fe7N3 stable at high pressures. [ABSTRACT FROM AUTHOR]

A new family of planar nanostructures having graphene-like electronic band structure is theoretically investigated by density functional theory (DFT). Based on general perturbation theory and a tight-binding model, it was shown that graphene-like planar structures, consisting of identical nanoparticles with relatively weak contacts between them, should have an electronic band structure with Dirac cones. Two such structures, consisting of 71- or 114-silicon atom nanoparticles, were investigated by DFT using VASP software package. The band-structure calculations show the presence of Dirac cones with electron group velocity equal to 1.05 × 105 and 0.53 × 105 m/s, respectively. By generalizing the theory, a new family of 3D structures having intersecting areas with linear dispersion in the band structures was derived. As an example, the band structure of identical 25-atom silicon nanoclusters arranged in a simple cubic lattice was calculated. It was shown that the band structure has features similar to the Dirac cones. [ABSTRACT FROM AUTHOR]

It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene and the large direct band gaps in MoS2 monolayers, arise from quantum confinement. However, the influence of reduced dimensions on electron-phonon (e-ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement is expected to produce a suppression of e-ph interactions in 2D systems with rigid boundary conditions, experimental verification of this has remained elusive. Here, we show that the e-ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3SiTe6 atomic crystals. When the thickness of the Nb3SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e-ph interactions caused by quantum confinement of phonons. [ABSTRACT FROM AUTHOR]

The parameters of equations of state of stoichiometric and nonstoichiometric phases of the γ′-FeN, ɛ-FeN, ɛ-FeN, ɛ-FeN, and ɛ-FeN iron nitrides in a pressure range up to 500 GPa have been determined using ab initio calculations. The points of the sharp drop and disappearance of the magnetic moment on iron atoms have been found. It has been shown that certain changes in the magnetic moment are accompanied by a change in the volume of a unit cell of the nitrides. The calculated parameters of equations of state demonstrate that the compressibility of both magnetic and nonmagnetic iron nitrides decreases monotonically with an increase in the content of nitrogen. [ABSTRACT FROM AUTHOR]

Bladder cancer is a significant health problem and is the fourth most common malignancy in the Western world. Histologically, transitional cell carcinoma (TCC) is the most common subtype and represents nearly 90% of all bladder cancers. Mutations of the tumour suppressor gene p53 are the most frequent genetic alteration found in human cancers, including urinary bladder carcinoma. Numerous studies have attempted to define p53 as a molecular marker with clinicopathological and predictive values. In this study we have investigated tissue samples of histopathologically confirmed TCC of the urinary bladder from 70 patients. Normal urinary bladder mucosa obtained from 40 patients with nonmalignant diseases were used as a negative control group. Immunofluorescence detection was performed using double-sandwich antibody technique, the microscope images were captured by digital camera and analyzed by ImageJ software. Corrected fluorescent intensity values corresponding to average malignant cells' nuclear p53 staining were calculated from each patient sample. We found that the mean corrected fluorescence intensity values of TCC samples grade I and II did not differ statistically significantly. On the contrary, those values were significant between the TCC grades II and III, as well as between grade I and III. In addition, a high correlation of p53 fluorescence intensity values from superficial TCC samples with the invasive TCC samples was found. However, the data showed no predictive value of p53 nuclear accumulation in TCC samples in terms of recidive, metastasis or cancer-related death, at least within the 2-years follow-up period. Given the relatively small size and heterogeneity of our patient groups, however, further studies are needed to demonstrate the clinicopathological value of digital quantitative immunofluorescent detection of nuclear p53 in TCC samples. [ABSTRACT FROM AUTHOR]

Influence of ordered monovacancies on elastic properties of graphene is theoretically investigated by density functional theory (DFT) calculations. Inverse linear dependence of the graphene Young's modulus on the concentration of vacancies has been revealed and migration rate of the vacancies has been calculated as a function of applied strain. It is shown that the migration rate can be controlled by applying various strains or temperatures. The influence of ordered monovacancies on magnetic properties of graphene as well as graphene-like hexagonal carbon silicide (2D-SiC) and the boron nitride (h-BN) structures is investigated. It is established that the presence of vacancies in all systems yields the appearance of local magnetic moment. However, in 2D-SiC structure the magnetic moment occurs only in the case of a Si vacancy. Influence of the distance between vacancies on the ferromagnetic or anti-ferromagnetic ordering for all structures is established. [ABSTRACT FROM AUTHOR]

The occurrence of an isolated malignant peripheral nerve sheath tumor (MPNST) of the kidney capsule is extremely rare and its presence may only be expressed by an insidious onset of non-specific and misleading symptoms with a predominance of lower back pain. A computer tomography (CT) scan (as the imaging procedure of choice) will demonstrate the tumor location and its relation to the surrounding structures. Tumor excision in toto is considered the treatment of choice, but it can be hazardous, especially if the tumor is adhering to the surrounding structures. Severe bleeding complications due to the damage of venous structures have to be considered, and establishing hemostasis may pose considerable difficulties. Therefore surgery should be attempted with full precautions and the patient must receive preoperative counseling. If malignancy can safely be excluded, a laparoscopic excision should be considered as an alternative treatment as recurrence is unlikely. Definition of the originating nerve might not always be possible, and a minor degree of neurological impairment has therefore to be anticipated. A case of an isolated MPNST of the, kidney capsule without neurofibromatosis is presented. The tumor was located in the fatty and fibrous capsule. It was surgically removed. The patient was further managed with radiotherapy and chemotherapy. An MPNST in such a location is very unusual. [ABSTRACT FROM AUTHOR]