STUDY OF CUTTING AND LABELING OF POLYMETHYLMETHACRYLATE USING A CO2 LASER

Progress in direct laser marking when processing plastics with unmatched quality of markings, contrast and speed. This article presents the latest generation of laser materials and laser equipment systems. When properly applied, laser marking can provide quality for production and add value to the appearance and function of the product.Describe the parameters influencing the depth of the laser marking of polymethylmethacrylate (PMMA) products. Experimental results are presented for determining the quality of cuts on the polymer surface at specific parameters - power and speed

BLACK SEA GAS SEEPAGE AND … 50 years University of Mining and Geology

ABSTRACT Only recently the international scientific community started to pay more attention of such natural, geological sources as submarine gas seepages and mud volcanoes and realized that they are significant sources of atmospheric methane. In this work the Black Sea is considered to be one of the most prolific areas in the World. Here we present a detail overview of the gas seepage areas documented offshore along the Bulgarian coastline, on the Georgian, Russian, Ukrainian and Turkish shelves as well as seabed gas venting structures as pockmarks, mud volcanoes, methane derived carbonate chimneys etc. Some speculations about massive gas outburst due to destabilization of gas hydrates are commented. The attempt to evaluate the annual quantities of gas methane venting from the seafloor, passing trough the water column and entering the atmosphere from gas seepage and venting structures shows values form 1.5 to 5.5 Tg (2.0-6.0x10 9 m 3 ) released from the Black Sea area, an area no exceeding one percent of the World Ocean aquatory

ELECTRIC DRIVE FOR PHOTOVOLTAIC MODULES DUAL AXIS TRACKING SYSTEM

The paper deals with the implementation of dual axis tracking system for photovoltaic modules in order to demonstrate the advantages of these systems in education. According to the main components – the system includes electronic module for control and two DC motors for each of the axes, respectively.The paper deals with the implementation of dual axis tracking system for photovoltaic modules in order to demonstrate the advantages of these systems in education. According to the main components – the system includes electronic module for control and two DC motors for each of the axes, respectively

PREVALENCE OF CARIES AND THE NEED FOR URGENT DENTAL TREATMENT AMONG CHILDREN WITH NEUROLOGICAL IMPAIRMENT IN NORTHEASTERN BULGARIA

Introduction: Oral health is extremely important for the quality of life and well-being. Findings reveal that people with special needs have difficulties in getting dental care, which increases their risk of oral diseases. The recommendations for dental examination are identical for patients with and without neurological impairment. This study aimed to assess the prevalence of caries and overall dental health among children with motor and mental disabilities in Northeastern Bulgaria. Methods: A total of 53 children with neurological impairment under the age of 18 were selected from Varna and Ruse from April to October 2017. Data on age, gender, height, weight, caregiver education level were collected. Information on oral hygiene behavior and diet was gathered as well. The 2013 World Health Organization standards for dental caries were used to assess the oral health status. The data were analyzed with the statistical package Jamovi v.2.2.2.0. Results: Children were divided into two groups – with predominantly motor or mental impairment. Both groups had high rates of caries and need for urgent dental treatment with no significant difference observed. The CPITN correlated positively with motor impairment (Spearman's rho= 0.393; p= 0.043). It was discovered that children with motor impairment had a higher prevalence of malocclusion than children with mental impairment (rho= -0.331; p= 0.016). The number of caries correlated as well with the type of occlusion (Spearman's rho=0.378; p=0.005), the dentition type (rho=0.343; p=0.012) and the age (rho= 0.372; p= 0.006). Conclusion: The study findings indicate that both types of neurological impairments were associated with a high frequency of caries and a significant need for urgent dental care. More frequent dental examination is thought to improve oral health. Nevertheless, more studies are required to substantiate this theory

The P5A ATPase Spf1p is stimulated by phosphatidylinositol 4-phosphate and influences cellular sterol homeostasis

P5A ATPases are expressed in the endoplasmic reticulum (ER) of all eukaryotic cells, and their disruption results in severe ER stress. However, the function of these ubiquitous membrane proteins, which belong to the P-type ATPase superfamily, is unknown. We purified a functional tagged version of the Saccharomyces cerevisiae P5A ATPase Spf1p and observed that the ATP hydrolytic activity of the protein is stimulated by phosphatidylinositol 4-phosphate (PI4P). Furthermore, SPF1 exhibited negative genetic interactions with SAC1, encoding a PI4P phosphatase, and with OSH1 to OSH6, encoding Osh proteins, which, when energized by a PI4P gradient, drive export of sterols and lipids from the ER. Deletion of SPF1 resulted in increased sensitivity to inhibitors of sterol production, a marked change in the ergosterol/lanosterol ratio, accumulation of sterols in the plasma membrane, and cytosolic accumulation of lipid bodies. We propose that Spf1p maintains cellular sterol homeostasis by influencing the PI4P-induced and Osh-mediated export of sterols from the ER

Functional Significance of Conserved Cysteines in the Extracellular Loops of the ATP Binding Cassette Transporter Pdr11p

The pleiotropic drug resistance (PDR) transporter Pdr11p is expressed under anaerobic growth conditions at the plasma membrane of the yeast Saccharomyces cerevisiae, where it facilitates the uptake of exogenous sterols. Members of the fungal PDR family contain six conserved cysteines in their extracellular loops (ECL). For the functional analysis of these cysteine residues in Pdr11p, we generated a series of single cysteine-to-serine mutants. All mutant proteins expressed well and displayed robust ATPase activity upon purification. Mass-spectrometry analysis identified two cysteine residues (C582 and C603) in ECL3 forming a disulfide bond. Further characterization by cell-based assays showed that all mutants are compromised in facilitating sterol uptake, protein stability, and trafficking to the plasma membrane. Our data highlight the fundamental importance of all six extracellular cysteine residues for the functional integrity of Pdr11p and provide new structural insights into the PDR family of transporters

Portable solar charger

El principal propòsit d’aquest projecte és crear un dispositiu que sigui net i respectuós amb el medi ambient. En el mateix temps està destinat a proporcionar una funció útil, tant en el món civilitzat, on l’electricitat és fàcilment accessible gairebé sempre, com en la naturalesa, on normalment és només una comoditat. Es pretén aprofitar una de les fonts d’energia més netes, el Sol. L’idea és desenvolupar un carregador solar portàtil altament eficient, que sigui compatible amb tants dispositius com sigui possible i que permeti el seu ús fins i tot durant la nit, quan no hi ha llum disponible. El concepte ha evolucionat a través de diversos canvis per arribar a ser una solució flexible i compacte

Portable solar charger

El principal propòsit d’aquest projecte és crear un dispositiu que sigui net i respectuós amb el medi ambient. En el mateix temps està destinat a proporcionar una funció útil, tant en el món civilitzat, on l’electricitat és fàcilment accessible gairebé sempre, com en la naturalesa, on normalment és només una comoditat. Es pretén aprofitar una de les fonts d’energia més netes, el Sol. L’idea és desenvolupar un carregador solar portàtil altament eficient, que sigui compatible amb tants dispositius com sigui possible i que permeti el seu ús fins i tot durant la nit, quan no hi ha llum disponible. El concepte ha evolucionat a través de diversos canvis per arribar a ser una solució flexible i compacte

Study on behaviour of centrifugal pump driven by medium-voltage induction motor during operation control

When studying electric drives, it is necessary to jointly analyze the processes in the electric power and control circuits of the electric motor as the main component determining the overall performance and in the mechanical executive part. The paper deals with the variation of the occurring torques, the currents flowing in the individual phases and the electrical power losses in the operation of a medium voltage electric drive of a pump unit from the point of view of energy efficiency. Emphasis is placed on the joint operation of the pump as a mechanism and the driving electric motor, studying the complete electromechanical system. During the studies, significant attention has been paid to the mathematical description and modeling with subsequent computer simulation of the ongoing electromagnetic and electromechanical processes. Different ways of controlling the motor have been applied - by softstarter and by frequency control. Also values for the duration of the start-up process have been obtained. Relevant conclusions have been drawn