[en] Full text: Fetal MRI is an already established method in prenatal imaging, with complementary to US role. Most common considerations for fetal MRI are CNS anomalies and urogenital anomalies. Practically, the most frequent indication is ultrasonographically established ventriculomegaly. We introduce our experience in fetal MRI, presenting the distribution of pathological findings and our protocols. We have examined 33 fetuses for a 3-year period. Among these 13 cases were affected by CNS anomalies (neural tube defects, Dandy-Walker, cerebellar hypoplasia, agenesis of corpus callosum, aqueductal atresia, etc.), 11 fetuses are affected by urogenital anomalies (pieloureteral stenosis, VUR, renal agenesis, etc.), 5 with other pathology (congenital tumor, ovarian cysts, etc.) and 4 are normal fetuses. The findings in most interesting cases are reviewed; in some of them we present imaging-pathological correlation and/or follow up imaging. Main advantages of fetal MRI over US consist of acquiring objective and reproducible images, giving the opportunity of multiple expert-leveled reviews; exceptionally high detail concerning CNS-anatomy; additional confidence in excluding presence of concomitant anomalies; independence from calavarial ossification and maternal obesity. Ultrasound remains the main tool for prenatal imaging. MRI has similar sensitivity and higher specificity, thus serving as an arbitrage method and improving accuracy about outcome prognosis

[en] Full text: Introduction: Gastroenteropancreatic Neuroendocrine Tumors (GEP - NET) are a heterogeneous group of tumors with different locations and many different clinical, histological, and imaging performance. In a part of them a secretion of various organic substances is present. The morbidity of GEP - NET in the EU is growing, and this leads to increase the attention to them. What you will learn: Imaging methods used for localization and staging of GEP - NET, characteristics of the study’s protocols; Classification of GEP - NET; Demonstration of typical and atypical imaging features of GEP - NET in patients registered at the NET Center at University Hospital ‘St. Marina’, Varna; Features of metastatic NET, The role of imaging in the evaluation of treatment response and follow-up of the patients. Discussion: The image semiotics analysis is based on 19 cases of GEP - NET registered NET Center at University Hospital ‘St. Marina’. The main imaging method is multidetector CT (MDCT), and magnetic resonance imaging (MRI ) has advantages in the evaluation of liver lesions and the local prevalence of anorectal tumors. In patients with advanced disease and liver lesions the assessment of skeletal involvement (MRI/ nuclear medical method) is mandatory. The majority of GEP - NET have not any specific imaging findings. Therefore it is extremely important proper planning and conducting of the study (MDCT and MR enterography; accurate assessment phase of scanning, positive and negative contrast). Conclusion: GEP - NET is a major diagnostic challenge due to the absence of typical imaging characteristics and often an overlap with those of the tumors of different origin can be observed. Therefore, a good knowledge of clinical and imaging changes occurring at different locations is needed. MDCT is the basis for the diagnosis, staging and follow-up of these neoplasms

[en] Pancreatic neuroendocrine tumors (PNET) are primary, usually we 11-differentiated pancreatic tumors. Their origin is not fully understood, but they are thought to develop from the pluripotent cells in the exocrine part of the pancreas. PNET are a heterogeneous group with different malignant potential. In some of the patients with sporadical forms of PNET there is association with other malignancies such as ovarian cancer, breast cancer, bladder and prostate cancers. We present a case of 50-year-old woman, with incidentally found pancreatic neoplasm, during a follow-up CT for ovarian cancer. Laparotomy and pancreatic biopsy are performed. Histological diagnosis confirms a well- differentiated endocrine tumor of the pancreas. (authors)

[en] Full text: The aim of this study is to evaluate patient and staff doses in fluoroscopically guided invasive diagnostic and interventional urology procedures. All the data were collected in the Emergency Hospital 'N. I. Pirogov'. While recording data for the patients, a real time dosimetry measurement of the medical staff was made. Air kerma-area product (KAP) was recorded for intravenous pyelogram (IVP), percutaneous nephrostomy (PN) and ureteral 'double-J' stenting. Patient data sex, age and weight were also taken. Staff doses were estimated with the system RaySafe i2. It contains four dosimeters, with a wireless connection to a real time display. The dosimeters were worn on the unprotected upper part of the body and measured the personal dose equivalent Hp(10). The mean KAP values for the procedures are: 3.21 Gy.cm"2 for IVP, 10.37 Gy.cm"2 for PN and 4.15 Gy.cm"2 for 'double-J' respectively. The highest staff dose for PN and 'double-J' is received by the urologist (160 μSv and 47.3 μSv, respectively), while for the IVP the radiographer has the highest exposure (20 μSv). Each member of the medical staff was on a different position in respect to the X-ray tube and the patient, which is the main reason for the differences in the staff doses. The variations in the mean patient and staff doses are mostly due to the interventions themselves, their complexity and the individual treatment of every patient. RaySafe i2 is very useful as guideline for making a choice of a better position and in the decreasing of radiation exposure to the staff

[en] Full text: This study continues an investigation of the preparation and characterization of amorphous phosphate coatings on carbon steel surfaces obtained in solutions of a new product, KAF-09 OF, developed at this university.; Gravimetric, electrochemical, and physical methods (XRD, TEM, XPS, and AFM) were used to determine the influence of pH (2÷6), temperature (20÷80°C), and agitation (0÷2000 min¹) on mass/thickness, composition, and structure of the coatings as well as on the passivation characteristics of the phosphating solutions having different pH, concentration, and temperature.; It was established that the coatings were of greatest mass/thickness at pH 2.0 for all the studied temperatures. Raising the temperature from 20 up to 80°C caused a two- to threefold increase of mass/thickness for the pH (2.0-6.0) applied. pH enhancement and agitation speed led to a higher tendency to anode passivity of the steel. The physical methods applied in this study were reliable to indicate composition, type of probable compound, and structure and roughness of the obtained phosphate coatings. The phosphate films were X-ray amorphous, with indefinite habit and very well expressive relief. The coatings contained basic elements such as oxygen, phosphorus, iron, molybdenum, calcium, which are probably combined as phosphate and oxide compounds.; The new phosphating product, KAF-09 OF, has successfully been employed in several Bulgarian companies for preliminary treatment to promote paint adhesion and corrosion resistance of painted articles

No abstract available

[en] The formation of phosphating coatings on carbon steels by novel baths containing zinc and zinc-manganese phosphates has been investigated. By gravimetric, chemical, electrochemical and physical methods are determined the characteristics of preparations (density, pH, conductivity, total and free acidity) and those of the produced coatings (thickness, phase and chemical compositions, structure, protection ability). The concentration range has been varied from 5 to 20% vol., while the temperature effects have been studied in the range from 20 to 80°C. The thicknesses of the coatings and the amount of the substrate dissolved have been determined. It is proved that Mn-phosphate decreases the coating thickness for all working solution concentrations and temperatures, at the same time increases the mass of dissolved metal of the substrate. The results obtained indicate that the coatings developed in zinc and manganese baths contain the following phases: hopeite, phosphophyllite, quasihopeite, strunzite and mixtures of them. (paper)

[en] The results of experimental studies of the transients’ parameters during the operation of a high-precision drive with a closed-loop control, which at the same time is an active damper, are presented. The amplitude-frequency characteristics of the damper and the vibration-isolating platform in semi-active mode based on four dampers and four elastic suspension assemblies are also shown. (paper)

[en] Most of the modern vacuum nanotechnological and research equipment is associated with the vibration control systems. Recently, systems based on composite materials, such as magnetorheological elastomers, are becoming more widely used. Such materials make possible to combine the functions of active, semi-active and passive vibration control in one device. This paper presents a research on the position error of the vibration control platform based on magnetorheological elastomers. This error occurs due to the inevitable unevenness of the top panel of the platform caused by the special properties of the elastomeric actuator. It leads to deviation of the platform from the horizontal plane position. The research on the measurement error was made by the contour estimations method and the correlation coefficients of the actuators movements were used. (paper)

[en] The most important requirement for any material used as an implant is to be biocompatible and not to cause undesirable effects in the human body. Corrosion of implants is included in the topic of biocompatibility because it is a determining factor in their sustainability and seamless fulfillment of their functional purpose. The work presents the results obtained in the comparative study of two austenitic stainless steels (Cr18Ni9 and Cr18Mn12N) in two models of artificial saliva, accepted as environments for testing the corrosion behavior of materials for these aims. The nature of the corrosion attack, the composition of the corrosion products at 37°C and the pH 5.5 and pH 6.75 of the model media were determined using physical methods such as SEM and EDX of investigation and analysis. It was found that Cr18Mn12N steel (0.61 % N), exhibits higher corrosion resistance. (paper)