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.

[Multiple system atrophy]. / Mul'tisistemnaya atrofiya.

The article presents a progressive neurodegenerative disease - multisystem atrophy, characterized by a combination of autonomic failure and various motor disorders, including parkinsonism and/or cerebellar ataxia; etiopathogenetic factors and variants of the clinical picture are described. We describe own clinical observation of a 59-old patient with cerebellar and bulbar syndromes, parkinsonism, pyramidal insufficiency, cognitive deficits, and autonomic dysfunction. The differential diagnosis included a whole range of neurodegenerative and hereditary diseases: Parkinson's disease, vascular parkinsonism, progressive supranuclear palsy, spinocerebellar ataxia, FXTAS, mitochondrial encephalopathies. The moderate severity of parkinsonism and the significant predominance of cerebellar symptoms and autonomic dysfunction make this clinical case difficult to diagnose. However, based on the life and disease history, clinical picture and research methods, a diagnosis of multiple system atrophy, cerebellar type (cerebellar, autonomic, bulbar syndrome, parkinsonism, pyramidal insufficiency and moderate cognitive impairment) was established. Differential search in such patients is a difficult task and includes a whole range of neurodegenerative and hereditary diseases due to the similarity of individual clinical and neuroimaging features and, unfortunately, the limited availability of molecular genetic diagnostic methods. However, earlier diagnosis is necessary to focus in time on the development of a personalized approach to the management of each such patient, taking into account the rate of symptoms development and steady progression, in order to ensure the longest possible survival time with an acceptable level of quality of life.

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).

[Difficulties of cerebral toxoplasmosis diagnosis in a patient with multiple sclerosis and HIV]. / Trudnosti diagnostiki tserebral'nogo toksoplazmoza u patsientki s rasseyannym sklerozom i VICh-infektsiei.

Toxoplasmosis is a widespread parasitic disease. It is caused by an intracellular parasite Toxoplasma gondii. It can affect various tissues and organs, forming cysts and continuing to replicate within them. In people with intact immune system, tissue cysts remain in latent state throughout their whole life. However, in cases of cellular immunodeficiency the infection can be reactivated, which leads to secondary generalization of the process. People with HIV most commonly present with cerebral toxoplasmosis. Non-specific neuroimaging signs, as well as absence of pathognomonic symptoms and specific laboratory data lead to difficulties of cerebral toxoplasmosis diagnosis, particularly in the cases with a history of multiple sclerosis that has similar clinical symptoms and brain MRI data suggesting of tumefactive multiple sclerosis image. A clinical case of cerebral toxoplasmosis in a female patient with multiple sclerosis and HIV infection is described.

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.

[IATROGENIC INJURIES DURING PREOPERATIVE MARKING OF NON-PALPABLE PATHOLOGICAL AREAS OF THE MAMMARY GLANDS].

The purpose of the study is to identify the types and frequency of medical mistakes made during preoperative marking of non - palpable pathological areas of the breast. We analyzed 60 clinical observations of patients with non-palpable, morphologically verified pathological areas in breast tissues, who underwent surgical intervention at the first stage of treatment with mandatory preoperative marking with a guide needle. The obtained data indicates that the error rate of radiologists when installing a tissue marker in a non-palpable breast neoplasm is 13.3% and is most often manifested by syntopia of the guide needle, which is detected at the beginning of the operation and requires implantation of additional tags. All clinical observations were accompanied by an increase in both the equivalent dose received by the patient and duration of the anesthesia. To improve the quality of interventional techniques performed on the breast, also to minimize the number of iatrogenic injuries, the radiologist must have spatial thinking, a sufficient amount of theoretical knowledge and practical skills.

[Transverse myelitis syndrom as a result of neuromyelitis optica spectrum disorders, systemic lupus erythematosus and myasthenia gravis combination]. / Sindrom perechnogo mielita v rezul'tate sochetaniya zabolevaniya spektra neirooptikomielita, sistemnoi krasnoi volchanki i miastenii gravis.

Neuromyelitis optica spectrum disorders (NMOSD) - autoimmune condition characterized by an inflammatory lesions mainly of the spinal cord with the development of longitudinally extensive transverse myelitis (LETM) and/or involvement of the optic nerve with the development of usually bilateral optical neuritis (ON). In recent years, there has been increased awareness that NMOSD can be combined with other autoimmune diseases, including myasthenia gravis (MG), systemic lupus erythematosus (SLE) et al. The simultaneous presence of several autoimmune diseases in one patient can adversely affect the course of each of the diseases, causing the so-called mutual burden or «overlap syndrome¼. In this article, we describe our own clinical observation of a 51-year-old woman of European origin who developed acute relapsing TM seropositive for AQP4-IgG, by 23 years after the diagnosis of generalized MG seropositive for antibodies to acetylcholine receptors (AChR-Ab) and the occurrence of SLE, criterially confirmed, several months after the initial TM attack. During the fourth TM attack, partial positive dynamics was achieved only against the background of the combined use of intravenous methylprednisolone (pulse therapy), high-volume plasma exchange, rituximab and cyclophosphamide. The NMOSD is a rare disease leading to severe disability. In patients with MG, when symptoms of damage to the central nervous system appear, an analysis should be performed for AQP4-IgG and possibly for antibodies to myelin glycoprotein of oligodendrocytes (MOG-Ab), as well as markers characteristic of systemic connective tissue diseases (SCTD). In patients with STDD, when symptoms of involvement nervous systemappear, testing for AQP4-IgG (and, if necessary, for MOG-Ab) should be performed to exclude NMOSD, as well as AChR-Ab (and, if necessary, antibodies against muscle specific kinase (MuSK-Ab)) to exclude MG.

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).

Mass spectrometric detection of the amino acid sequence polymorphism of the hepatitis C virus antigen.

A method for detection and identification of the hepatitis C virus antigen (HCVcoreAg) in human serum with consideration for possible amino acid substitutions is proposed. The method is based on a combination of biospecific capturing and concentrating of the target protein on the surface of the chip for atomic force microscope (AFM chip) with subsequent protein identification by tandem mass spectrometric (MS/MS) analysis. Biospecific AFM-capturing of viral particles containing HCVcoreAg from serum samples was performed by use of AFM chips with monoclonal antibodies (anti-HCVcore) covalently immobilized on the surface. Biospecific complexes were registered and counted by AFM. Further MS/MS analysis allowed to reliably identify the HCVcoreAg in the complexes formed on the AFM chip surface. Analysis of MS/MS spectra, with the account taken of the possible polymorphisms in the amino acid sequence of the HCVcoreAg, enabled us to increase the number of identified peptides.

[Atomic force microscopy fishing of gp120 on immobilized aptamer and its mass spectrometry identification].

A method of atomic force microscopy-based fishing (AFM fishing) has been developed for protein detection in the analyte solution using a chip with an immobilized aptamer. This method is based on the biospecific fishing of a target protein from a bulk solution onto the small AFM chip area with the immobilized aptamer to this protein used as the molecular probe. Such aptamer-based approach allows to increase an AFM image contrast compared to the antibody-based approach. Mass spectrometry analysis used after the biospecific fishing to identify the target protein on the AFM chip has proved complex formation. Use of the AFM chip with the immobilized aptamer avoids interference of the antibody and target protein peaks in a mass spectrum.