rss_2.0Materials Sciences FeedSciendo RSS Feed for Materials Sciences Sciences Feed technology to enhance compliance and oral health. of different instruments used for composite filling polishing.<abstract> <title style='display:none'>Abstract</title> <p>Introduction: Improper finishing and polishing of fillings leads to surface roughness of the restoration which leads to excessive plaque accumulation, gingival irritation, increased surface staining and poor aesthetics of restored teeth. Therefore, it is essential to use polishing instruments and pastes as a final step of simple caries treatment in order to achieve optimal long-time results. The aim of this study is to evaluate the efficiency of 4 different finishing and polishing instruments used for surface smoothening of aesthetic restorative materials in vitro. Materials and methods: 40 composite (Reality X) samples were prepared in vitro. Their surface irregularities were measured along 3 diagonals before and after polishing. Sof-Lex discs (3M Espe), rubber cones (Kenda), Arkansas stone (Fino) and polishing paste and a professional toothbrush (Kerr) were used for polishing. Each sample was polished under 5N pressure for 30 seconds at 3000 rpm. The surface roughness was than measured using a profilometer. Statistic analysis was performed using ANOVA and unpaired T-tests, the significance level was set at a value of p&lt;0.05. Results: Based on the mean values, the smallest roughness was found in the control group- 0.11, while the highest in the rubber polishers and Arkansas stone group- 0.47 and 0.48. The values for the Sof-Lex disc group and the polishing paste-toothbrush group were 0.40 and 0.39. Statistical analysis showed no significant differences between the four groups. Conclusion: It is mandatory to use polishing tools in order to obtain a smooth surface of the restoration and avoid the unwanted long-term complications. Polishing using brush and abrasive paste produced the smoothest surface of the composite.</p> </abstract>ARTICLE2021-06-12T00:00:00.000+00:00The assessment of two-way relationship between periodontal diseases and diabetes mellitus.<abstract> <title style='display:none'>Abstract</title> <p>Periodontal disease and diabetes mellitus have been said to have a two-way relationship, with diabetes leading to oral disease and periodontitis exacerbating hyperglycemia. The universal biologic mechanisms and demographic and behavioral risk drivers, underlying these associations in both directions, are also described.</p> <p>Both the diseases are chronic and they are affecting large population worldwide. Periodontitis is also recognized as the sixth major complication of diabetes, while diabetes mellitus is a metabolic disorder which has an impact on the global health and plays a crucial role in the pathogenesis of periodontitis.</p> <p>The aim of this article is to illustrate a systematic and comprehensive analysis of the literature, on the mutual relationship between diabetes mellitus and periodontal diseases, trying to identify if the prevalence of periodontitis is higher in diabetics or if the incidence of diabetes is greater in patients with periodontal disease. Moreover, our intention is to increase the level of awareness of diabetologists and dentists about the interaction between this two pathologies.</p> <p>Oral and periodontal health should be promoted as integral components of diabetes management. Dental professionals can detect unrecognized potential dysglycemia and refer for medical examination. Furthermore, the control of periodontal disease may enhance glycemic control which contributes to a better control of periodontal disease.</p> </abstract>ARTICLE2021-06-12T00:00:00.000+00:00Fear and dental anxiety in children: a study of the contributing factors.<abstract> <title style='display:none'>Abstract</title> <p>Introduction: Dental fear and anxiety are an important issue affecting children’s oral health and clinical management, and also an insufficiently studied subject in dentistry.</p> <p>Aim of the study: The aim of this study was to better understand the child patient - dentist versus dentist - child patient relationship and study the dental fear and anxiety of children in order to improve the dental office practice. Material and methods: In this study a personalized questionnaire was created and applied on a number of 333 children, in 4 schools from Mures county, Romania, on girls and boys between the ages of 8 and 13. The questionnaires used emoticons alongside words in order to better determine the state of anxiety created by the dental appointment and everything that it entails. All data and results obtained were analyzed using Excel and Graph Pad Prism 5.0 software.</p> <p>Results: Out of 333 patients, 133 subjects (40%) were 8-10-year-old, 143 subjects (42.9%) 11 - 13 years and 57 subjects (17.1%) were over 14 years. 175 girls (52.6%) and 158 boys (47.4%) demonstrated their courage and desire in participating in our study. It was determined that fear of dental appointments was caused in children over 14 years of age. The state of relaxation is generally enjoyed by urban children (45%) and those aged 11-13 years (37.1%); the percentage of boys in this category is an interesting aspect (40.5%).</p> <p>Conclusion: Dental anxiety is multifactorial and is far more complex than can be explained by a single contributing factor. The direct involvement of the child from the perspective of maintaining dental health, leads to the elimination of the state of fear and anxiety. Regular visits to the dental office, on the initiative of the child patient itself can reduce the anguish.</p> </abstract>ARTICLE2021-06-12T00:00:00.000+00:00Contribution to the study of improving the aesthetics of the smile by repairing and reshaping the incisors with composite materials.<abstract> <title style='display:none'>Abstract</title> <p>Introduction. Dental aesthetics, although it seems something relative and difficult to evaluate, it is governed by a series of laws and rules that connect the dental disciplines, creating a unitary whole. It is structured by rules, perfected by artistic sense and by the inclination towards beauty of all specialists in dento-facial cosmetics.</p> <p>The aim of the study is to highlight an overview of aesthetic factors to consider when restoring anterior teeth with direct composite materials.</p> <p>Material and methods. A total of 25 patients were included in the study where the anterior teeth were restored using Gradia Direct Anterior (from GC) and Filtek Z550 (from3M-ESPE) composite kits, in perfect isolation using rubber damn, with a separate appointment after 24 hours for the polishing step, for which Rainbow Kit Technic and polishing Platina Hi-Gloss (from Prevest) paste were used. While the replacement of the tooth defect, we ensured that the composite increment, which we used should not be more than 2mm in thickness, and light cured for 20 seconds as the producer recommends. In none of all tooth shape modification (elongation in incisal zone) we did not modify the occlusion, by eliminating all premature contacts. All patients included in the study have signed the informed consent and agreed to participate in this research.</p> <p>Results. From a total of 25 patients, we repaired 20 central incisors with the mesial (18 cases) or distal (2 cases) angles fractured, in different accidents, 5 cases with diastema by small shape of the crown or malposition of one of the central incisors.</p> <p>Conclusions. Restoring the incisal angle or the incisal edge and refining a natural and improved smile of the patient is e very frequent dental intervention, especially nowadays when aesthetics plays an important role in the social society.</p> </abstract>ARTICLE2021-06-12T00:00:00.000+00:00Compendium of current ceramic materials used for the CAD/CAM dentistry.<abstract> <title style='display:none'>Abstract</title> <p>Nowadays, patients require the highest quality of treatment, but generally prefer to spend as little time as possible in the dental chair. Therefore, there is significant benefit for using new technologies such as CAD/CAM (computer aided design/computer aided manufacturing), which provides both quality and speed. There is an increase in ceramic materials and ceramic blocks/discs available, with varying properties. This has resulted in some confusion and difficulty in making an informed decision about which material is best for a specific clinical situation. The objective of this review is to provide an overview and comparison of basic mechanical properties of currently used CAD/CAM ceramic materials based on a review of the currently available literature.</p> </abstract>ARTICLE2021-06-12T00:00:00.000+00:00Improved rack and pinion drive<abstract> <title style='display:none'>Abstract</title> <p>A typical rack and pinion drive set is comprised of a rack and a pinion. There is an inter-tooth clearance between the mating teeth of the rack and the pinion, which has advantages and disadvantages. The disadvantage of this clearance is the errors that occur in the positioning of the machine tool during set-up. Elimination of clearance between teeth is possible by using a pinion drive with two pinions. This ensures continuous contact between the teeth, regardless of the direction of machine movement.</p> <p>These are found on new machines, while older machines do not have such a solution. This paper presents a solution with two pinions, which can be used in such older machines and which makes it possible to achieve qualitative parameters that were not possible before.</p> </abstract>ARTICLE2021-09-04T00:00:00.000+00:00Rzeszów as an example of a ‘new town’ tailored for the modern era<abstract> <title style='display:none'>Abstract</title> <p>The city life cycle is an issue that can be considered from many perspectives. Klaassen’s period cycle is the basic model of city life: urbanisation– suburbanisation–deurbanisation–reurbanisation. In each of these periods, cities develop by, building and transforming their structures. This article presents various approaches to shaping new urban spaces using the city of Rzeszów as an example. In the city’s history, three periods are distinguished during which structures referred to as the ‘new town’ were created in the 16<sup>th</sup> and 20<sup>th</sup> centuries and continue to be created now. After analysing the site-forming processes, the most important features of new-town urban systems are compared.</p> </abstract>ARTICLE2021-04-22T00:00:00.000+00:00The formation of zinc coatings in nanocrystallised zinc powders<abstract> <title style='display:none'>Abstract</title> <p>The kinetics of and mechanism for galvanising low-carbon steel (0.2% C) were examined in powder media which were pre-treated to obtain a fine nanostructured ZnO layer on the surface of zinc powder particles. The effective diffusion coefficient of Zn atoms through the ZnO shell was estimated to be in the order of 1·10<sup>−10</sup> m<sup>2</sup>·s<sup>−1</sup>. The contribution of the Zn-gas evaporation/condensation microprocesses, which could occur in relation to the above diffusion through a nanostructured surface layer, was evaluated with numerical calculations in the temperature range of 550–950 K and for an average particle size of ZnO up to 100 nm. Our results suggest that the outward diffusion of metallic zinc takes place from the core of powder microparticles across the nano-grain boundaries of their modified surface layer, and can be further intensified by the presence of other inter-phase defects, such as nano-porosity.</p> </abstract>ARTICLE2021-07-12T00:00:00.000+00:00The application of topological data analysis to human motion recognition<abstract> <title style='display:none'>Abstract</title> <p>Human motion analysis is a very important research topic in the field of computer vision, as evidenced by a wide range of applications such as video surveillance, medical assistance and virtual reality. Human motion analysis concerns the detection, tracking and recognition of human activities and behaviours. The development of low-cost range sensors enables the precise 3D tracking of body position. The aim of this paper is to present and evaluate a novel method based on topological data analysis (TDA) for motion capture (kinematic) processing and human action recognition. In contrast to existing methods of this type, we characterise human actions in terms of topological features. The recognition process is based on topological persistence which is stable to perturbations. The advantages of TDA are noise resistance and the ability to extract global structure from local information. The method we proposed in this paper deals very effectively with the task of human action recognition, even on the difficult classes of motion found in karate techniques. In order to evaluate our solution, we have performed three-fold cross-validation on a data set containing 360 recordings across twelve motion classes. The classification process does not require the use of machine learning and dynamical systems theory. The proposed classifier achieves a total recognition rate of 0.975 and outperforms the state-of-theart methods (Hachaj, 2019) that use support vector machines and principal component analysis-based feature generation.</p> </abstract>ARTICLE2021-08-18T00:00:00.000+00:00The influence of water price and the number of residents on the economic efficiency of water recovery from grey water<abstract> <title style='display:none'>Abstract</title> <p>This article presents the results of an analysis of the economic viability of using an installation for the treatment of grey water. Economic indicators in the form of simple payback time (SPBT) and net present value (NPV) were used in the analysis. The use of a dual water supply system should theoretically enable the reduction of the costs of both water supply and sewage disposal, ensuring investment profitability. The article presents the impact of the number of residents as well as the impact of water and sewage on the profitability of using example water-recovery systems. It was found that both factors have a huge impact on the result of the economic analysis. For a small number of residents and at a low price of water supply and sewage disposal, it is not profitable to invest in a water-recovery system. This is due to the high price of purification devices.</p> </abstract>ARTICLE2021-02-05T00:00:00.000+00:00Analysis of the possibility of employing 3D printing technology in crisis situations<abstract> <title style='display:none'>Abstract</title> <p>Events related to climate change and the increase in the occurrence of natural disasters, as well as the increasing incidence of new diseases, have all caused the prominence of regional security and crisis management around the world to rise. Three-dimensional printing, which has seen noteworthy developed in recent years, both in terms of print parameters, and the magnitude of the production potential, may prove helpful in this matter. Enormous opportunities have arisen which, if properly directed, can save human life and preserve health in crisis situations, when traditional supply chains could be disrupted or even prevented. The use of additive technologies, however, has its limitations and in order to be able to take full advantage of the opportunities they offer, a legitimate functional system should be created and embedded within proper structures to support crisis management. This paper presents the advantages and disadvantages of using 3D printers and the possibility of their implementation as part of the current crisis-response systems. The article proposes a model for incorporating additive technologies into the crisis-management system.</p> </abstract>ARTICLE2021-06-20T00:00:00.000+00:00A suitability assessment using an instrumented impact test of the use of selected structural steel grades on the basis of their changes in response to exposure to fire<abstract> <title style='display:none'>Abstract</title> <p>In this article, changes occurring in structural steel after exposure to fire are described and discussed. The steel structure before and after fire determines its susceptibility to brittle cracking. The individual phases of cracking are described and interpreted on the basis of a load-displacement graph, directly obtained from the Charpy impact test. The relationship between the intensity of individual fracture energies and the type and appearance of the sample fractures are demonstrated. The program of planned Charpy impact tests and expected hazards after the exposure to fire of selected steel grades are presented. Standard simplified load-displacement graphs are assigned to the steel transition curve. The course of various cracking mechanisms occurring in the case of brittle fractures and plastic fractures are discussed. The aim of this article is to evaluate the possibility of the assessment of structural steel after a fire based on results obtained during the Charpy impact test.</p> </abstract>ARTICLE2021-04-27T00:00:00.000+00:00Humic substances and significance of their application – a review<abstract> <title style='display:none'>Abstract</title> <p>This paper is based on recent articles regarding applications of humic substances (HSs). HSs are natural organic materials, which have a number of potential applications. Furthermore, HSs are cheap, widespread and obtainable from bio-waste materials. HSs can be used as organic compound sorbents or in detoxification. They are applied as organic additives due to their positive effect on soil and plants, even under stress conditions. HSs reduce water consumption and minimise environmental problems. HSs are utilised for the remediation of multi-metal contaminated soils and as substitutes for synthetic washing agents. From an environmental engineering point of view, it is beneficial to remove HSs from municipal management, where they are undesirable (by-products of disinfection) and to utilise them where they are valuable. The aim of this article is to provide a greater insight into research about the applications of HSs.</p> </abstract>ARTICLE2021-08-18T00:00:00.000+00:00A review of modern materials used in military camouflage within the radar frequency range<abstract> <title style='display:none'>Abstract</title> <p>The article presents an overview of materials which can be employed used to camouflage objects on the modern battlefield in the radar frequency range.</p> </abstract>ARTICLE2021-02-10T00:00:00.000+00:00Mixing effects in the river downstream from pollution discharge point<abstract> <title style='display:none'>Abstract</title> <p>This paper follows the propagation of pollution in a river with a rectangular cross-section of the river bed and a variable cross-sectional velocity. The calculations were made for steady flows and steady pollutant concentrations. To approximate the velocity distribution in the river bed a set of equations for current and vorticity functions was solved. The distribution of pollutant concentrations in the river was calculated from a bidirectional advection and turbulent diffusion equation. Analysis of the distribution of concentrations leads to the conclusion that the effects of transverse advection associated with a lateral inflow of pollutants disappear relatively quickly. Therefore, the distribution of concentrations in cross sections further downstream from the point of pollutant discharge can be determined quite accurately just from an advection-diffusion model, with no transverse advection effects included. Such a level of accuracy is usually sufficient to assess the impact of a pollution source on the aquatic environment. The transverse mixing of pollutants in the stream proceeds slowly and creates a large mixing zone in which the concentrations of pollutants (low but still significant for water quality) can be detected in cross-sections that are remote from the pollutant discharge point. Transverse advection may be ignored while calculating concentrations in remote cross sections at straight watercourse sections and in steady state conditions.</p> </abstract>ARTICLE2021-04-18T00:00:00.000+00:00Small Historical Centres: an opportunity for the “smart” revitalization of Inner Areas in the Post (post) COVID Era<abstract> <title style='display:none'>Abstract</title> <p>The Pandemic is forcing everyone to become aware of the need for a change in the cultural and socio-economic paradigms of recent decades.</p> <p>During the twentieth century, on the one hand, entire populations concentrated in urban areas with ever higher population densities, at the same time giving rise to the phenomenon of “urban sprawl” or “suburbanization”.</p> <p>On the other hand, entire territories have been abandoned (the so-called “inner areas”).</p> <p>Now, we can define territorial rebalancing strategies based precisely on the reactivation of “inner areas”. Strategies that, in the Post (post) COVID era will have to be not only resilient, but anti-fragile. And the key is precisely in the future of the smaller historical centres.</p> <p>This article aims to review the strengths and weaknesses of small historic centres, outlining possible scenarios for their “smart” revitalization and for a true sustainable and inclusive development.</p> </abstract>ARTICLE2021-04-18T00:00:00.000+00:00The new function of architectural monuments – a comparative analysis of two different cases: Palazzo Querini Stampalia and the Fondaco dei Tedeschi building<abstract> <title style='display:none'>Abstract</title> <p>This paper discusses the long-term vision of the historic city development, where buildings assume a new function over time. The discussion is based on the example of Palazzo Querini Stampalia and Fondaco dei Tedeschi – two monuments restored to Venice in a new, different role. In the comparative analysis of the transformation of the buildings, particular attention was paid to the cultural, social and economic context of the city. This article aims to review the strengths and weaknesses of the new-use scenarios, outlining the renovation of the monuments and its added value for cities. The author concluded that no matter what the new function of the building is, it is worth renovating them, because this way the heritage can survive and this should be the central objective of a long-term vision.</p> </abstract>ARTICLE2021-09-10T00:00:00.000+00:00A historical study of utility gardens within the Klemensów palace and park complex<abstract> <title style='display:none'>Abstract</title> <p>The main purpose of the research was the historical study of utility gardens, which are separate functional and spatial sections of the palace and park complex in Klemensów. These include a walled-off garden constituting a unique man-made landscape acting as a fruit and vegetable garden, as well as a tree nursery. The utility gardens in Klemensów were a place of acclimation and reproduction of seeds and saplings imported to Poland. Thanks to the expanding possibilities of obtaining and exchanging them from foreign and domestic garden nurseries, over time, the garden in Klemensów became a unique collector’s garden.</p> <p>The research introduces rarely discussed problems in the field of conservation, including the adaptation of historic utility gardens. The results include the analyses of archival materials which have not been previously developed.</p> </abstract>ARTICLE2021-07-12T00:00:00.000+00:00HMM-based phoneme speech recognition system for the control and command of industrial robots<abstract> <title style='display:none'>Abstract</title> <p>In recent years, the integration of human-robot interaction with speech recognition has gained a lot of pace in the manufacturing industries. Conventional methods to control the robots include semi-autonomous, fully-autonomous, and wired methods. Operating through a teaching pendant or a joystick is easy to implement but is not effective when the robot is deployed to perform complex repetitive tasks. Speech and touch are natural ways of communicating for humans and speech recognition, being the best option, is a heavily researched technology. In this study, we aim at developing a stable and robust speech recognition system to allow humans to communicate with machines (robotic-arm) in a seamless manner. This paper investigates the potential of the linear predictive coding technique to develop a stable and robust HMM-based phoneme speech recognition system for applications in robotics. Our system is divided into three segments: a microphone array, a voice module, and a robotic arm with three degrees of freedom (DOF). To validate our approach, we performed experiments with simple and complex sentences for various robotic activities such as manipulating a cube and pick and place tasks. Moreover, we also analyzed the test results to rectify problems including accuracy and recognition score.</p> </abstract>ARTICLE2021-02-05T00:00:00.000+00:00en-us-1