THE USE OF LIQUID PROBES BASED ON AN EUTECTIC SOLUTION FOR STUDYING THE CONDUCTING PROPERTIES OF THIN FILMS

Работа посвящена разработке модульной четрырехзондовой установки с использованием жидкого контакта на основе индий-галлиевого эвтектического раствора (EGaIn), с помощью которого можно создать прижимные жидкие контакты, не вносящие механические деформации в измеряемые структуры. Предлагается использовать данную установку для измерения вольт-амперных характеристик тонкопленочных образцов. Предполагается модульная схема измерений. Каждый зонд управляется четырьмя моторами для позиционирования и выдавливания капли из шприца для формирования нужного размера пятна контакта. Используется оптический контроль для подготовки зондов и измерения диаметра сформированных контактных областей. Подобраны параметры изготовления жидких зондов, а именно скорости выдавливания и перемещения зонда вдоль вертикальной оси для формирования капли конической формы . Управление установкой осуществляется в среде LabView. The work is devoted to development of a modular four-probe setup using a liquid contact based on an indium-gallium eutectic solution (EGaIn), which can be used to create clamping liquid contacts that do not introduce mechanical deformation into the measured structures. It is proposed to use this setup for measuring the current-voltage characteristics of thin-film samples. A modular measurement scheme is assumed. Each probe is driven by four motors to position and expel a drop from the syringe to form the desired contact area size. Optical control is used to prepare the probes and measure the diameter of the formed contact areas. The parameters for the manufacture of liquid probes are selected, namely, the speed of extrusion and movement of the probe along the vertical axis to form a conical droplet. The installation is controlled in the LabView environment.

Experimental and Numerical Investigation of Contact Parameters in a Dovetail Type of Blade Root Joints

this paper focuses on the contact characteristics of the blade root joints subjected to the dry friction damping under periodic excitation. The numerical method and experimental procedure are combined to trace the contact behavior in the nonlinear vibration conditions. In experimental procedure, a novel excitation method alongside the accurate measurements is used to determine the frequencies of the blade under different axial loads. In numerical simulations, local behavior of contact areas is investigated using the reduction method as a reliable and fast solver. Subsequently, by using both experimental measurements and numerical outcomes in a developed code, the global stiffness matrix is calculated. This leads to find the normal and tangential stiffness in the contact areas of a dovetail blade root joints. The results indicate that the proposed method can provide an accurate quantitative assessment for investigation the dynamic response of the joints with focusing the contact areas.

Sectional matrix solutions: the distorted truth

Sectional matrix techniques offer more predictable solutions to achieving contact areas when placing direct interproximal posterior composites than circumferential matrix techniques, resulting in reduced reported complaints of food packing from patients. Despite this, a large majority of UK dentists and therapists don't currently use them. Sectional matrix systems are technique-sensitive to use, which can be a barrier to implementation for inexperienced users. The matrices can easily distort during their placement and stabilisation and when placing the restorative material. This can result in unwanted, clinically relevant problems in the resulting restorations, some of which may not be discernible once they have occurred. This paper explores the advantages and disadvantages of sectional matrices and the processes and techniques involved in their use, before discussing the potential for distortion at each step. It offers solutions to some of the commonly seen problems which will provide more predictable outcomes for those already using these techniques and encourage non-users to add them to their armamentarium.

Mixing, Mass Transfer, and Numerical Models

We want to eliminate dissolved impurities to another phase: slag, gas, solid, or a molten metal that has limited solubility in the main metal. The various phases may be in the form of droplets, bubbles, particles, or walls. The contact areas with metal should be large. The aim in reactor design and operation is to achieve relatively high velocities and small dimensions. Relations for mass transfer are also included since the behaviour of systems with molten metals may be different from that usually treated in chemical engineering. In the field of turbulence the Prandtl eddy length is important for describing removal to walls. Hydrogen in aluminium and the pick-up of hydrogen in aluminium from water vapour is studied in some detail, measured, and modelled. It is taken into account that hydrogen gas is two-atomic. The approach concerning aluminium may be applied to a range of metals.

Removal of Dissolved Impurities from Molten Metals

Impurities are transferred out at the boundary of the liquid. Velocities normal to the boundary are small. Therefore, for efficient removal contact areas and times should be large. Transfer depends on the chemical and physical properties of the liquid and the phase that captures the impurities at the boundary. This phase may be a liquid, gas (vacuum) or solid. Properties can be described in terms of equilibrium and empirical mass transfer coefficients. Vacuum may be applied to remove volatile elements. Refining can be carried out by partial solidification or fractional crystallisation, using the segregation that occurs during freezing of an alloy. Finally, an element can be added to form a reactive compound followed by removal of the compound by sedimentation or filtration.

Changes in elbow joint contact area in symptomatic valgus instability of the elbow in baseball players

The aim of this study was to evaluate the joint contact area of the dominant side and that of the non-dominant side without valgus instability in symptomatic pitchers. Ten symptomatic elbow medial ulnar collateral ligament (UCL) deficient baseball pitchers participated in this study. Computed tomography (CT) data from the dominant and non-dominant elbows were obtained with and without elbow valgus stress. The CT imaging data of each elbow joint were reconstructed using a 3D reconstruction software package, and the radiocapitellar and ulnohumeral joint contact areas were calculated. The center of the contact area and the translation from the position without stress to the position with valgus stress were also calculated. With elbow valgus stress, the contact area changed, and the center of the radiocapitellar joint contact area translated significantly more laterally in the dominant elbow than in the non-dominant elbow (p = 0.0361). In addition, the center of the ulnohumeral joint contact area translated significantly more posteriorly in the dominant elbow than in the non-dominant elbow (p = 0.0413). These changes in contact areas could be the reason for cartilage injury at the posterior trochlea in pitchers with UCL deficiency.

Reference map of localization of contact points and contact areas of posterior teeth

The aim of the study: to find correlations in age-related characteristics of the localization and shape of the contact points in permanent posterior teeth and to develop a reference card for dentists, reflecting the age-related characteristics of the localization, shape and size of the contact areas of the posterior teeth in adults.Materials and research methods. The linear dimensions, area, shape, vertical and horizontal position in the interdental space of 1224 contact points of the posterior teeth in 236 patients aged 20 to 59 years was assessed based on a comprehensive analysis of intraoral radiographs performed using the bitewing technique, the results of the study of contact points using floss, displaying contact points on dental impressions made using a special technique.Research results. It was found that the interdental spaces of the posterior teeth in adult patients are characterized by the following features: the contact areas of the teeth are displaced in the vestibular direction, the buccal and lingual (palatal) interdental embrasures are asymmetric; dynamics of the depth of occlusal interdental embrasures, linear dimensions and area of contact areas is expressed as average digital values for different age groups: 20-40 years: contact areas – 1×2 mm, S = 2 mm2, depth of occlusal interdental embrasure - 1.5 mm ; over 40 years old: contact pads – 1.5×3 mm, S = 4.5 mm2, the depth of the occlusal interdental embrasure – 1.0 mm.Conclusion. On the basis of the data obtained, a «Reference map of the localization of contact points and contact areas of posterior teeth in adult patients» was proposed, which allows a dentist to obtain data on the features of the topography of the contact areas of the posterior teeth, taking into account the patient’s age during planning and performing interproximal caries treatment.

Treatment effectiveness evaluation of dental caries as a factor affecting patients’ quality of life

Background: The study of the patient’s quality of life is an important condition for assessing the effectiveness of the treatment and the clinical condition of patients after treatment, in addition to objective diagnostic methods. The purpose of the study was to investigate the dynamics of changes in the quality of life of dental patients suffering from caries of the contact areas of the lateral group of teeth, after treatment in accordance with the established plan for the use of various matrix systems, in the study groups. Material and methods: The study involved 147 patients: 48 patients of the 1st experimental group; 54 patients of the 2nd experimental group; 45 patients of the 3rd experimental group. Results: In the course of the study, it turned out that such a criterion as the quality of life is an informative dynamic indicator, the value of which depends on the method of treatment used. Conclusions: In the course of the study, the effectiveness of the use of a separation-retaining device for the restoration of the lateral group of teeth during the treatment of caries in the contact areas of the teeth was assessed as a factor influencing the quality of life of patients.

AGE RELATED PECULIARITY OF THE CONTACT POINTS OF THE POSTERIOR TEETH FROM THE POINT OF VIEW OF RESTORATIVE DENTISTRY

Reconstruction of the age-related anatomical and physiological features of the contact surfaces and contact points inherent in natural teeth in the treatment of caries of posterior teeth with a direct restoration with light-cured composite is one of the unsolved problems of practical dentistry. The study is devoted to the determination of age-related characteristics of the localization and shape of contact points of posterior teeth in permanent dentition. The assessment of localization and shape of 1224 contact points of posterior teeth in 236 patients aged 20 to 59 years was carried out. Comparison of data about the surface area, shape, vertical and horizontal positions of contact points related to teeth anatomic structures in the interdental space was performed. The analysis of interproximal intraoral radiography data, examination and measurement of the parameters of interdental contacts using dental floss, analysis of the display of contact points on dental impressions made according to a special technique were carried out. The localization of the contact areas of the posterior teeth with a displacement in the vestibular direction, the associated asymmetry of the buccal and lingual (palatal) interdental embrasures, as well as a gradual increase in the surface area of contact areas and a decrease in the depth of the occlusal interdental embrasures, correlated with the age of the patients, were recorded. The average numerical values of the listed parameters are derived, taking into account the age of the patients. Anatomical and topographic features of the interdental spaces of the posterior teeth in adult patients are characterized by the following features: the contact areas of the posterior teeth are displaced in the vestibular direction, the buccal and lingual (palatal) interdental embrasures are asymmetric; dynamics of the depth of occlusal interdental embrasures, linear dimensions and area of contact areas is expressed as average digital values for different age groups: 20-40 years: contact areas – 1×2 mm, S = 2 mm2, depth of occlusal interdental embrasure – 1.5 mm; over 40 years old: contact pads – 1.5 × 3 mm, S = 4.5 mm2, the depth of the occlusal interdental embrasure – 1.0 mm.