PBr3 adsorption on a chlorinated Si(100) surface with mono- and bivacancies.

For the most precise incorporation of single impurities in silicon, which is utilized to create quantum devices, a monolayer of adatoms on the Si(100) surface and a dopant-containing molecule are used. Here, we studied the interaction of phosphorus tribromide with a chlorine monolayer with mono- and bivacancies using a scanning tunneling microscope (STM) at 77 K. The combination of different halogens in the molecule and the adsorbate layer enabled unambiguous identification of the structures after PBr3 dissociation on Si(100)-Cl. A Cl monolayer was exposed to PBr3 in the STM chamber, which allows us to compare the same surface areas before and after PBr3 adsorption. As a result of this comparison, we detected small changes in the chlorine layer and unraveled the molecular fragments filling mono- and bivacancies. Using density functional theory, we found that the phosphorus atom occupies a bridge position after dissociation of the PBr3 molecule, which primarily bonds with silicon in Cl bivacancies. These findings provide insight into the interaction of a dopant-containing molecule with an adsorbate monolayer on Si(100) and can be applied to improve the process of single impurity incorporation into silicon.

New insights into the structure of the Ag(111)-p(4 × 4)-O phase: high-resolution STM and DFT study.

The atomic structure of the Ag(111)-p(4 × 4)-O phase was reexamined with scanning tunneling microscopy (STM) and density functional theory. We discovered two different phases with the same (4 × 4) periodicity and demonstrated that the accepted Ag6 model is incompatible with high-resolution oxygen-sensitive STM images. Using bias dependencies of the STM images, we have shown that the p(4 × 4) phase is highly nonuniform, with local oxygen coverage varying from 1/8 ML up to 1/2 ML.

Enhancing the reactivity of Si(100)-Cl toward PBr3 by charging Si dangling bonds.

The interaction of the PBr3 molecule with Si dangling bonds (DBs) on a chlorinated Si(100) surface was studied. The DBs were charged in a scanning tunneling microscope (STM) and then exposed to PBr3 directly in the STM chamber. Uncharged DBs rarely react with molecules. On the contrary, almost all positively charged DBs were filled with molecule fragments. As a result of the PBr3 interaction with the positively charged DB, the molecule dissociated into PBr2 and Br with the formation of a Si-Br bond and PBr2 desorption. These findings show that charged DBs significantly modify the reactivity of the surface toward PBr3. Additionally, we calculated PH3 adsorption on a Si(100)-2 × 1-H surface with DBs and found that the DB charge also has a significant impact. As a result, we demonstrated that the positively charged DB with a doubly unoccupied state enhances the adsorption of molecules with a lone pair of electrons.

[Features of CD68+ and CD163+ expression in the urinary bladder as a marker of cancer in age aspects.]

The study presents a study of the expression of CD68+ and CD163+ in the bladder as a marker of cancer in age-related aspects. As part of the work performed, 35 patients with bladder cancer with histological verification of the disease aged 36 to 70 years were studied. The role of CD68+ and CD163+ cells in bladder reactions can be interpreted as an indicator of diagnostic parameters of the activity of tissue macrophages and endothelial cells in cancer. Their progression during oncogenesis is especially pronounced in the group of middle-aged patients. In old age, there is a decrease in these parameters, which indicates in favor of a decrease in the activity of the development of oncological processes with age. The combination of morphological and immunological atypism leads to a violation of the functional specialization of the organ.

Vacancy diffusion on a brominated Si(100) surface: Critical effect of the dangling bond charge state.

Silicon dangling bonds (DBs) on an adsorbate-covered Si(100) surface can be created in a scanning tunneling microscope (STM) with high precision required for a number of applications. However, vacancies containing DBs can diffuse, disrupting precisely created structures. In this work, we study the diffusion of Br vacancies on a Si(100)-2 × 1-Br surface in an STM under typical imaging conditions. In agreement with previous work, Br vacancies diffuse at a positive sample bias voltage. Here, we demonstrated that only vacancies containing a positively charged DB hop across the two atoms of a single Si dimer, while vacancies containing neutral and negatively charged DBs do not. Calculations based on density functional theory confirmed that positively charged Br (and Cl) vacancies have a minimum activation barrier. We propose that diffusion operates by both one-electron and two-electron mechanisms depending on the applied voltage. Our results show that the DB charge has a critical effect on the vacancy diffusion. This effect should be taken into account when imaging surface structures with charged DBs as well as when studying the diffusion of other atoms and molecules on the Si(100) surface with vacancies in an adsorbate layer.

Adsorption of molecular iodine on the Ag(111) surface: Phase transitions, silver reconstruction, and iodide growth.

Room temperature adsorption of molecular iodine on Ag(111) has been studied by scanning tunneling microscopy (STM), low energy electron diffraction, Auger electron spectroscopy with factor analysis, and density functional theory (DFT). At the chemisorption stage, iodine first forms a (3×3)R30° structure. Further iodine dosing leads to continuous commensurate-incommensurate phase transition, taking place via the formation of striped superheavy domain walls. As a result, the uniaxially compressed (13 ×3-R30°) phase is formed at an iodine coverage (θ) of 0.38 ML. At θ > 0.38 ML, first-order phase transition begins, leading to the formation of hexagonal moiré-like phases, which exhibit an anomalously large corrugation in STM (0.8-2.3 Å). In the range of 0.40-0.43 ML, the compression of hexagonal phases occurs, which ends at the formation of the (7 × 7)R21.8° structure at saturation. The DFT calculations allow us to explain the anomalous atomic corrugation of the hexagonal phases by the strong violation of the atomic structure of the substrate including up to ten layers of silver. Iodine dosing above 0.43 ML leads to the growth of 2D islands of silver iodide. The STM images of the silver iodide surface demonstrate a clear visible hexagonal superstructure with a periodicity of 25 Å superimposed with a quasi-hexagonal atomic modulation. DFT calculations of the atomic structure of AgI islands point to the formation of a sandwich-like double layer honeycomb structure similar to the case of I/Ag(100).

Reactivity of the Si(100)-2 × 1-Cl surface with respect to PH3, PCl3, and BCl3: comparison with PH3on Si(100)-2 × 1-H.

Despite the interest in a chlorine monolayer on Si(100) as an alternative to hydrogen resist for atomic-precision doping, little is known about its interaction with dopant-containing molecules. We used the density functional theory to evaluate whether a chlorine monolayer on Si(100) is suitable as a resist for PH3, PCl3, and BCl3molecules. We calculated reaction pathways for PH3, PCl3, and BCl3adsorption on a bare and Cl-terminated Si(100)-2 × 1 surface, as well as for PH3adsorption on H-terminated Si(100)-2 × 1, which is widely used in current technologies for atomically precise doping of Si(100) with phosphorus. It was found that the Si(100)-2 × 1-Cl surface has a higher reactivity toward phosphine than Si(100)-2 × 1-H, and, therefore, unpatterned areas are less protected from undesirable incorporation of PH3fragments. On the contrary, the resistance of the Si(100)-2 × 1-Cl surface against the chlorine-containing molecules turned out to be very high. Several factors influencing reactivity are discussed. The results reveal that phosphorus and boron trichlorides are well-suited for doping a patterned Cl-resist by donors and acceptors, respectively.

The Use of Atomic Force Microscopy in Comprehensive Assessment of the "Mother-Placenta-Fetus" System in Obstetric and Endocrine Pathology during Pregnancy.

Atomic force microscopy is not very popular in practical health care, therefore, its potential is not studied enough, for example, in obstetrics when studying the "mother-placenta-fetus" system. Our study summarizes the possibilities of using atomic force microscopy for detection of various circulatory disorders and vascular changes at the microscopic level in the uterus (endometrium and myometrium), placenta, and umbilical cord in the main variants of obstetric and endocrine pathology. For instance, in the case of endocrine pathologies, changes in the form of stasis, sludge, diapedesis, ischemia, destruction and separation of endotheliocytes in villous blood vessels were found in the mother. The oxygen content in erythrocytes also naturally decreased in pathologies; poikilo- and anisocytosis were observed.

New atomic-scale insights into the I/Ni(100) system: phase transitions and growth of an atomically thin NiI2 film.

We use a traditional surface science approach to create and study an atomically thin NiI2 film (a promising two-dimensional ferromagnetic material) formed on nickel substrate as a result of molecular iodine adsorption. The I/Ni(100) system was examined with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and density functional theory calculations. We found out that the iodine adsorption on Ni(100) at 300 K leads to the formation of non-equilibrium phases, whereas the adsorption at elevated temperature (≥390 K) gives rise to the thermodynamically stable phases. In both cases, a simple p(2 × 2) structure is formed at 0.25 ML. As more iodine is adsorbed at 300 K, the p(2 × 2) phase is replaced by the small coexisting domains of c(3 × 2) and c(6 × 2) phases both corresponding to the coverage of 0.33 ML, while adsorption at elevated temperature results in the formation of only one c(3 × 2) phase. At further iodine adsorption the c(3 × 2) phase transforms into the c(5 × 2) one, while the c(6 × 2) phase - into the one both corresponding to the coverage of 0.40 ML. In addition to simple chemisorbed phases, a new shifted-row reconstruction of Ni(100) induced by iodine adsorption was discovered. At coverages exceeding 0.40 ML, we observed complex LEED patterns and superstructures in STM and assigned them to specific surface reconstructions. We also found that prolonged iodine dosing leads to the nucleation of nickel iodide islands and the growth of a 2D atomically thin iodide film partially exfoliated from the substrate.

[Uteroplacental blood flow in maternal diabetes mellitus]. / Matochno-platsentarnyi krovotok pri sakharnom diabete u materi.

Various uteroplacental blood flow disorders, their diagnosis, and correction, especially if the maternal obstetric history is burdened by endocrinopathy, still remain an urgent obstetric problem. OBJECTIVE: To study blood flow in the vessel-red blood cell segment and to search for changes in both the vessels of the villous tree of the placenta and uterus and the properties of blood corpuscles, by using modern microscopy methods (scanning probe microscopy, atomic force microscopy). MATERIAL AND METHODS: For macroscopic and microscopic examinations, fragments of the placenta, umbilical cord, and uterus were taken; venous blood samples were collected from patients without endocrinopathy, with gestational diabetes mellitus (GDM) or type 1 and type 2 diabetes mellitus (DM) prior to delivery. The data were statistically processed using both parametric (Student's t-test) and nonparametric (Fisher's exact test) methods. RESULTS: The authors found that microangiopathy and other metabolic changes in diabetes mellitus could lead to villous stromal sclerosis, the appearance of intermediate villi, changes in blood vessel shape, relief tortuosity, depth, and area, endothelial cell destruction, stasis, and thrombosis. In these endocrinopathies, there were also changes in maternal red blood cells: their polymorphism was observed and geometric parameters and deformability were impaired. In this case, cell shape impairment correlated with the severity of the above described vascular complications. CONCLUSION: The use of modern microscopy methods makes it possible to diagnose uteroplacental blood flow changes even in early pregnancy and to prevent the progression of uteroplacental blood flow disorders and placental insufficiency.

Evaluation of New Immunohistochemical Approaches for the Study of Kidney Tumors in Geriatric.

Kidney malignancies are among the most deadly genitourinary tumors. It is more common in males and is often seen in people aged 60-70 years old. The incidence rate of kidney cancer seems to be increasing. One reason for this may be the fact that imaging techniques, such as computed tomography scans are more commonly used. These tests may lead to the accidental detection of more kidney cancers. Fortunately, kidney cancer is often detected in the early stages, when the tumor is small and confined to the kidney. The objective of this study was the development of new diagnostic immunohistochemical methods. Clinical examination material of 134 people, including 94 (70%) males and 40 (30%) females, were used in this study. Immunohistochemical staining of tryptase was carried out in compliance with the requirements using Anti-Mast Cell Tryptase antibodies. Goat anti-mouse antibodies #AS-M1-HRP were used as secondary antibodies, visualized with ImmPACTTM DAB Peroxidase Substrate Kit (#SK-4105) according to the instructions of the manufacturer. The nuclei were counterstained with Mayer's hematoxylin, and the sections were embedded in a permanent mounting medium. The immunohistochemical study showed an increase in both tryptase- and chymase-positive mast cells in the renal parenchyma, compared with the control group. The number of mast cells with tryptase expression directly in the tumor was significantly less than the peritumoral localization. A similar pattern was observed for chymase-positive mast cells as the content of the tumor was more than 10 times higher than the intratumoral arrangement. The histological and immunological characteristics did not differ in different age groups. The immunohistochemical method of research in the diagnosis of renal tumors plays an important diagnostic and prognostic value. It can assist pathologists in difficult and ambiguous cases to correctly diagnose renal tumors. This will make it possible to prescribe the correct treatment and predict the course of malignant tumor growth in patients.

Adsorption of molecular oxygen on the Ag(111) surface: A combined temperature-programmed desorption and scanning tunneling microscopy study.

The adsorption of O2 on Ag(111) between 300 and 500 K has been studied with temperature-programmed desorption (TPD) and scanning tunneling microscopy (STM). At the first stage of adsorption, the disordered local oxide phase (commonly looking in STM as an array of black spots) is formed on the surface irrespective of the substrate temperature. The maximum concentration of black spots was found to be ≈0.11 ML, which corresponds to an oxygen coverage of ≈0.66 ML. Taking into account that the nucleation of the Ag(111)-p(4 × 4)-O phase starts after the saturation of the disordered phase, one can conclude that its coverage is at least not less than 0.66 ML. The analysis of STM and TPD data shows that the thermodesorption peak (m/e = 32) at 570 K is related exclusively to the decomposition of the p(4 × 4) phase, while the local oxide phase does not contribute to desorption.

Adsorption of O_{2} on Ag(111): Evidence of Local Oxide Formation.

The atomic structure of the disordered phase formed by oxygen on Ag(111) at low coverage is determined by a combination of low-temperature scanning tunneling microscopy and density functional theory. We demonstrate that the previous assignment of the dark objects in STM to chemisorbed oxygen atoms is incorrect and incompatible with trefoil-like structures observed in atomic-resolution images in current work. In our model, each object is an oxidelike ring formed by six oxygen atoms around the vacancy in Ag(111).

[The mother-placenta-fetus system in diffuse toxic goiter: Morphopathological aspects].

OBJECTIVE: to compare the clinical and morphological parallels of the mother-placenta-fetus system in diffuse toxic goiter (DTG) through current morphological examinations. SUBJECTS AND METHODS: Sixty-five women whose pregnancy occurred with DTG were examined using both clinical and morphological studies (light, scanning electron, and atomic-force microscopies and macro- and microelement analysis); the placenta and uterus were investigated. RESULTS: Destructive changes and microrelief impairment, resulting from circulatory disorders (ischemia) and hemic hypoxia, were observed in the presence of DTG during pregnancy. Abnormal placental immaturity developed; the number of terminal villi decreased; sclerosis occurred. The magnitude of changes showed up to a greater extent in the myometrium, umbilical cord, and placenta of women, whose pregnancy occurred with DTG, and in patients with disease recurrence. In preeclampsia, plethora, stasis, and thrombosis were added to circulatory disorders. CONCLUSION: Not only the diagnosis itself of DTG, but also the type of its course and the pattern of obstetric disease, primarily preeclampsia, affect the state of structural components of the uteroplacental unit.

Comparative characterization of the skull bones after implantation of titanium biocomposites containing BMP-2 in their coating structure.

The skull bone tissue was studied under conditions of implantation of Grey nanostructured titanium containing biocomposites and bone morphogenetic protein-2 in the coating structure. Implantation of sandblast processed titanium led to more rapid formation of the bone tissue than the use of titanium biocomposites with microarch oxidation (due to porous surface). The type of metal processing was inessential for nanocomposites. Morphogenetic proteins stimulated regeneration and facilitated the formation of structures characteristic of the bone tissue.

[Blood rheological characteristics of uteroplacental blood flow in severe gestosis].

OBJECTIVE: To investigate the clinical and morphological features of uteroplacental blood flow during pregnancy in severe gestosis. SUBJECTS AND METHODS: One hundred and twenty-five patients with severe gestosis were examined. Scanning probe and electron microscopy with macro- and microelement analysis and transmission microscopy were used to study their placentas, umbilical cords, endometrium, myometrium, and maternal blood in severe gestosis. RESULTS: It is shown that circulatory disorders in the structural components of the examined tissues and organs, as well as changes in cytoarchitectonics and red blood cell functional properties may be a component of the trigger of disseminated intravascular coagulation, followed by impaired maternal and fetal vital activity. CONCLUSION: The investigation of the pathomorphological features of the microcirculatory bed in the mother-placenta-fetus system in gestosis has shown that possible methods of their correction should be further sought.

[Impairments in the ultrastructure and macro- and microelement composition of hard tooth tissues in caries in patients with hypothyroidism and in those without thyroid disease].

Extracted teeth were studied in patients with hypothyroidism, by applying electron and atomic force microscopy. This method allows one to have extended morphometric characteristics. The patients with hypothyroidism were found to have superficial and internal changes in the enamel, dentin, and cement of intact and carious teeth. The macro- and microelement composition of teeth were investigated. In hypothyroidism, the resistance of dental tissue depends on the homogeneous structure of enamel and dentin.

[Has the era of warfarin terminated?].

Warfarin has for a long time been considered the "gold standard" of oral anticoagulant therapy. Positive effects of this agent are unambiguously supported by accumulated evidence-based data convincingly confirming a decrease in the risk for thrombolytic complications in patients with many diseases of the cardiovascular system: atrial fibrillation, thrombosis of deep veins of extremities, pulmonary artery thromboembolism. However, warfarin has a series of disadvantages complicating its practical application: the necessity of individual adjustment of the dose to maintain the International Normalized Ratio (INR) within the limits of the target values, clinically significant interactions with other drugs and foodstuffs. In this connection, the advent of new oral anticoagulants such as dabigatran, rivaroxaban, and apixaban is associated with great hopes concerning increased efficiency and safety of anticoagulant therapy. However, while the results of large-scale clinical trials are promising, the data on using these agents in real clinical practice suggest that prescription and administration of new oral anticoagulants should be approached with great caution, thoroughly weighing potential risks and benefits. Therefore, switching over the patients with the already adjusted dosage of warfarin and stable values of the INR to new drugs seems hardly advisable.

[Bone tissue regeneration in the use of nanoimplants].

The authors studied regenerative and reparative processes in the rat skull bone tissue when nanostructured titanium implants with different types of coating were applied. Optical, luminescence, scanning electron, and probe microscopies were used to assess results. The use of biological nanocomposites was established to considerably accelerate skull bone regeneration processes.