Detail Reproduction Research Articles

Tea Tree Oil Effect on Dimensional Change and Detail Reproduction of Addition Silicon Impression Material

Objective: Impression materials are thought to be the one of the primary sources of cross infection between patients and dentists. However, it was discovered that disinfection of the impression is not conducted routinely in ordinary dental treatment. Disinfection of addition silicon impression, whether by immersion or spray should not produce dimensional or detail errors. The purpose of this study was to examine the immersion of addition silicon impression material in tea tree oil and its influence on dimensional stability and detail reproduction of the addition silicon imprint material. Materials and Methods: This study employed a total of 120 heavy- and light-body addition silicon impression material specimens. The specimens were randomly sorted and immersed into six groups. These test groups where four concentrations of TTO (0.25%, 0.5%, 0.75%, and 1%), and the other two groups were distilled water (negative control) and 2% glutaraldehyde (positive control). All specimens were immersed for 10 minutes in the testing solutions. Each of the six groups had 20 specimens separated into two subgroups. Results: There were no statistically significant differences in linear dimensional changes and detail reproduction among all test groups. Conclusion: The addition silicon impression material may be safely submerged in TTO for 10 minutes to disinfect it without impairing its dimensional correctness or detail replication of the impression.

Antimicrobial Efficiency of Hypochlorous Acid Incorporation and its Effect on Surface Properties of Irreversible Hydrocolloid Materials

Objective: Conventional approaches for disinfection, including spraying and immersion, resulted in only surface disinfection of impressions. As a result, self-disinfecting impression materials incorporated with antimicrobial compounds require more extensive studies. The incorporation of a disinfectant into irreversible hydrocolloid impression materials could eliminate the need for the disinfection step by conventional approaches, including spraying and immersion which only result in surface disinfection of impressions. The study was aimed to investigate the effect of incorporation of hypochlorous acid in irreversible hydrocolloid materials on antimicrobial efficiency, detail reproduction, and dimensional stability. Materials and Methods: Hypochlorous acid (HOCl) was used in two concentrations, 100 ppm and 200 ppm, and mixed with alginate powder to compare with the control group (distilled water mixed with alginate). Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosawere chosen for assessing the antimicrobial activity with the disk diffusion test. In addition, the dimensional stability and reproduction of details were tested. Results: The results revealed that both HOCl concentrations of 100 ppm and 200 ppm imposed significant antimicrobial activity against all three tested microorganisms. There was no significant difference regarding reproduction of details, but the addition of the antimicrobial had a significant adverse effect on the alginate’s dimensional stability. Conclusion: It may be concluded that the incorporation of HOCL into irreversible hydrocolloid impression material resulted in an impression with antimicrobial activity. In addition, there was no effect on the impression materials ability to reproduce surface details, but the antimicrobial addition may affect its dimensional stability.

Особливості проведення лабораторної роботи «Вимірювання опору розтіканню струму заземлюючих пристроїв, питомого опору ґрунту, ізоляції мереж та електроустановок» за допомогою віртуального лабораторного стенда

The materials of this scientific article consider the possibility of using a virtual laboratory stand during the laboratory work carried out by students of higher education institutions under the name «Measurement of the resistance to the spread of the current of grounding devices, the specific resistance of the soil, the insulation of networks and electrical installations». This laboratory work is included in the curriculum of the normative educational component «Occupational safety in the industry and civil protection». The article examines the specific advantages of using a virtual stand, in particular its role in improving the quality of the educational process, expanding access to resources, and optimizing educational costs. The purpose of this article is to consider the main possibilities of using the proposed virtual laboratory stand as an innovative approach in the study of complex technical processes and ensuring a high level of training during laboratory work on the topic «Measurement of resistance to the spread of current of grounding devices, soil resistivity, insulation of networks and electrical installations». This laboratory work is a component of the curriculum of the normative educational component aimed at forming in students the ability to identify, analyze and evaluate potential risks associated with the production environment, and which is entitled «Occupational Safety and Civil Protection». Particular attention is paid to the methodology of conducting laboratory work using a virtual stand, including steps for configuring the software, algorithms for performing measurements and analyzing the received data. Methods of simulating various measurement conditions are described in detail, allowing students to practice scenarios that would be difficult or dangerous to implement in real conditions. In the materials of the article, an overview of the interface and functionality of the developed computer program, which reproduces the control components of real laboratory equipment and is intended for the implementation of the functions of a virtual laboratory stand, is reviewed, the key capabilities of the proposed program are described, including the simulation of various laboratory scenarios and the availability of theoretical materials necessary for preparing and conducting a laboratory session, as well as a detailed reproduction of the appearance and control components of real experimental laboratory equipment, which contributes to the creation of a feeling of working with physical devices, the implementation of mathematical models that accurately describe the dependence of output parameters on input parameters. It was also found that the use of similar technologies during other laboratory works from the above-mentioned normative educational component requires further thorough systematic research and publication of their results.

Study on the quality of reproduction of graphical linear micro-images using electrophotographic printing

Today’s market of visual graphic communication includes many various advertising, publishing and packaging products printed on different materials. Many products are printed using conventional printing technologies such as offset printing or flexography, in addition to digital ones like Electrophotography and Ink Jet. The graphic images on prints often contain extremely fine graphic details, such as micro-lines or micro-text elements, which are part of various identification, security markings, codes, etc. It is a very important task to optimally model these micro-images on printed graphic communication products at the design stage, in order to ensure their brightness, legibility and geometric dimensions meet the requirements, not only immediately after printing, but also, for example, after a certain period during the life cycle of the printed product after exposure to the sunlight spectrum, or to other mechanical or environmental effects. This paper presents a methodology and results for the assessment of the quality of the reproduction of fine image details, i.e. the micro-lines of different widths arranged on the print in different directions. A specially developed original digital press quality control wedge with monochromatic micro-lines, microtext and screen dots bars of CMYK colours was applied to assess the accuracy of micro-image reproduction. In this part of the study, the wedge fields with positive micro-lines arranged in different directions individually and in groups were analysed. The width of the micro-lines was measured under the microscope to assess the accuracy of the dimensional reproduction and the deviations from the nominal value. To assess the influence of different parameters of the system “printing press-paper-inks” on the reproduction of image microelements, the prints for this part of the study were printed using electrophotographic printing techniques on different dry-toner printing presses on different types of paper. The width and deviations of the micro-lines on the print were measured along the print direction, perpendicular and at 45˚ to the print direction. Measurements of the reproduction accuracy of monochrome micro-line images, printed on dry-toner electrophotographic presses, showed that the accuracy of micro-line reproduction depends not only on the printing system, its resolution and the characteristics of the paper, but also on the direction of the positioning of the micro-lines on the printed sheet. The obtained results allow us to compare the capability of digital printing systems to reproduce linear micro-images on visual graphic communication products of any size and geometric orientation, to select optimal systems for printing specific products, and to model the layout of micro-images on products at the design stage, by assessing the orientation of the micro-images on the printed sheet.

Comparative Evaluation of Disinfection Protocols for Dental Impressions in Prosthodontics.

In prosthodontics, dental impressions are essential for creating precise dental restorations. However, these impressions are susceptible to microbial contamination, which can pose a risk of infection to patients. Consequently, effective disinfection methods are crucial to prevent postoperative infections. This study aims to evaluate the effectiveness of various disinfection techniques for dental impressions used in prosthodontics. A total of 148 poured dental impressions were randomized into three disinfection groups: immersed in 0.5% sodium hypochlorite, 2% glutaraldehyde, or 0.2% chlorhexidine solution. The bacterial contamination was evaluated by direct colony-forming unit (CFU) counting, while the dimensional accuracy and surface detail duplication of each resin sample were determined as physical properties. Data were analyzed using SPSSversion 23.0 (IBM Corp., Armonk, NY). Either analysis of variance (ANOVA) with the option for post-hoc or non-parametric tests was used to investigate and compare the efficacy of the better disinfection protocols where the p-value was considered significant if less than 0.05. Glutaraldehyde showed the lowest mean CFU count (2.5 log10 CFUs), followed by sodium hypochlorite (3.2 log10 CFUs) and chlorhexidine (3.5 log10 CFUs). All disinfection protocols were able to significantly reduce microbial contamination when compared with the control group (p < 0.05). The results of the physical property assessment demonstrated acceptable dimensional accuracy in all tested protocols, with slight differences recorded between them regarding the reproduction of surface detail. More specifically, the mean dimensional deviation was in the range between 0.02 and 0.04 mm, while scores for surface detail reproduction ranged from 2 to 4. The ANOVA results revealed significant differences in microbial contamination levels (F(2, 145) = 5.72, p = 0.007) and dimensional accuracy (F(2, 145) = 3.45, p = 0.032) between the various disinfection protocols. This study enlightens the effective sterilization protocol to be adopted in prosthodontics for dental impressions. Glutaraldehyde was most effective in microbial reduction, while sodium hypochlorite and chlorhexidine were equally effective. Therefore, clinicians must be vigilant in assessing the type of microbial flora that can be encountered during prosthodontic procedures while choosing disinfection protocols for patient safety and quality of impressions.

Effect of Dental Stone Fluidity Properties, Compatibility with Impression Materials, and Detail Reproduction after Incorporation of 0.2% Chlorhexidine Solution

Effect of Dental Stone Fluidity Properties, Compatibility with Impression Materials, and Detail Reproduction after Incorporation of 0.2% Chlorhexidine Solution

Advancements in Dental Casting Materials &amp; Their Forensic Significance

Abstract: This research explores various dental casting materials &amp; their significance in forensic science. Traditional materials, such as- Dental stone, Plaster of Paris, &amp; Dental wax have long been utilized in forensic investigations. However, advancements in materials science have led to the development of newer, more versatile options, such as- Epoxy resins, Polyurethane, &amp; Alginate substitutes. Each material offers distinct advantages &amp; limitations concerning ease of use, accuracy, &amp; durability. Dental stone, a widely used &amp; employed material, provides excellent detail reproduction &amp; stability but lacks flexibility. Plaster of Paris, though economical, may not yield precise replicas due to its brittle nature. Dental wax, appreciated for its malleability &amp; is susceptible to form deformation &amp; degradation over time. In contrast, modern alternatives like- Epoxy resins &amp; Polyurethane boast superior strength &amp; dimensional stability, making them ideal for long-term storage of dental impressions. Epoxy resins, in particular, offer high fidelity reproduction of dental structures &amp; resistance to moisture, temperature fluctuations. Polyurethane, known for its flexibility &amp; durability, enables the creation of resilient dental models suitable for extensive forensic analysis. Furthermore, Alginate substitutes have gained popularity for their ease of use &amp; compatibility with 3D Printing technology. These materials also offer quick setting times &amp; adequate detail capture, facilitating rapid production of dental models for forensic examination. While, Traditional materials continue to serve a purpose, the adoption of advanced casting materials has revolutionized forensic odontology by enhancing- efficiency, precision &amp; archival integrity

Побудова твердотілої моделі історичного об’єкту: на прикладі форту «Марушка Ліс»

Purpose of this work is to use terrestrial laser scanning for analysis and construction of a digital model of the fort “Marushka Lis” focusing on the process of data collection, processing, and their further use, particularly for web mapping of post-military sites. In the modern world, the preservation and restoration of historical structures is an important task that requires the application of advanced technologies. Methodology. Terrestrial laser scanning serves as an indispensable tool in this process, providing accurate and detailed spatial data. A technological scheme for creating a digital model of a historical object has been proposed. The study of historical objects using various methods of information collection was considered, namely: topographic surveying, terrestrial digital photogrammetry, terrestrial laser scanning, ground-penetrating radar studies, tachymetric surveying, GNSS. The methodology for creating a digital model of a historical object and the presented technological scheme, which includes data collection, processing of the obtained results, and output data, are described. Results. A comprehensive approach was applied to create the model, which included studying the history of the object, terrestrial laser scanning, terrestrial digital photogrammetry, and conducting geodetic measurements. A key aspect was the accurate and detailed reproduction of all architectural and structural elements of the fort. The use of software such as Leica Cyclone REGISTER 360, Autodesk ReCap, and Autodesk Revit allowed the integration of collected data into one accurate and detailed model. The sequential execution of work according to the proposed methodology enabled the creation of a digital model of the fort “Marushka Lis.” Scientific novelty and practical significance. The scientific novelty lies in the use of terrestrial laser scanning and 3D modeling for the reconstruction of a destroyed post-military object. The obtained digital model of the fort “Marushka Lis” will be used in web mapping of post-military sites in Lviv region.

IMPROVED RENDERING METHOD OF SKELETAL ANIMATION ON CONTROL POINTS BASE

Current research builds on an investigation of skeletal animation methods, focusing on the use of control points for managing limb movements. It thoroughly considers the relevance and significance of the chosen topic and its impact on creating realistic and effective visual projects in the modern world of digital graphics and reproduction. The research includes an analysis of the impact of sample quantity on the frame transitions smoothness and the rendering time to achieve a balance between quality and efficiency. It also involves refining the method through adaptation for execution on a GPU graphic processor. Studied Blender 3D engines (EEEVE and Cycles) allowed to analyze rendering performance on different computational architectures – CPU and GPU depending on sample values (60 and 128), frame number (250, 500, and 1000), and also the frame frequency at a rate of 30 frames per second. The goal of the research was an achievement of optimal balance between performance and realism in animation details reproduction. Three experiments were done to reach this goal and make the following conclusion: graphical processor utilization through the Cycles engine demonstrated a rendering acceleration of 43%, ranging from minimal to maximum settings. In the same time, the acceleration of the hybrid system via the EEVEE engine showed an acceleration of 15.2% only.

A Detailed Numerical Model for a New Composite Slim-Floor Slab System.

The paper concerns the numerical modelling of a new slim-floor system with innovative steel-concrete composite beams called "hybrid beams". Hybrid beams consist of a high-strength TT inverted cross-section steel profile and a concrete core made of high-performance concrete and are jointed with prestressed hollow core slabs by infill concrete and tie reinforcement. Such systems are gaining popularity since they allow the integration of the main structural members within the ceiling depth, shorten the execution time, and reduce the use of concrete and steel. A three-dimensional finite element model is proposed with all parts of the system taken into account and detailed geometry reproduction. Advanced constitutive models are adopted for steel and concrete. Special attention is paid to the proper characterisation of interfaces. The new approach to calibration of damaged elastic traction-separation constitutive model for cohesive elements is applied to concrete-to-concrete contact zones. The model is validated with outcomes of experimental field tests and analytical calculations. A satisfactory agreement between different assessment methods is obtained. The model can be used in the development phase of a new construction system, for instance, to plan further experimental campaigns or to calibrate simplified design formulas.

Effect of propolis on the mechanophysical properties of addition silicon dental impression material

Background Dental impressions should be disinfected to stop the transmission of germs among dental workers since they provide a risk of diseases. The aim of this study was to examine the effects of two disinfectants (16 mg/ml propolis and 5.25% sodium hypochlorite) on the detail reproduction, linear dimensional change, compatibility with gypsum products, wettability, and surface roughness of addition silicon material. Methods Ninety specimens were created using Addition silicon impression material, and they were then divided into three groups at random. Ten specimens from each test group were used in each test. Utilizing apparatus made in accordance with ISO 4823:2015, detail reproduction, linear dimensional change, and compatibility with gypsum products are assessed. A digital Profilometer was uutilized to evaluate surface roughness, and a Goniometer was utilized to evaluate wettability by taking the contact angle. Before testing, the specimens were immersed for 10 minutes each in two disinfection solutions: 16 mg/ml propolis and 5.25% NaOCL. The control group received no disinfection. One-way ANOVA tests and the Kruskal-Wallis test, which was statistically significant at a level of p 0.05, were used to examine the data. Results Comparing the linear dimensional change, surface roughness, and wettability of Addition silicon specimens immersed in 16 mg/ml propolis, 5.25% NaOCL, or the control group demonstrated statistically significant differences (p&lt; 0.05), while details reproduction and compatibility with gypsum revealed statistically no significant differences (p &gt; 0.05). Conclusion Within the parameters of this study, the addition silicon can be immersed in 16 mg/ml propolis for 10 min. to disinfect it without compromising its dimensional accuracy, detail reproduction, compatibility with gypsum products, surface roughness, or wettability.

Перспективи застосування віртуального лабораторного стенда «Дослідження та оцінювання електромагнітного поля на робочих місцях»

This article examines the potential of using a virtual laboratory stand to perform laboratory work on the topic "Research and assessment of the electromagnetic field at workplaces," which is included in the curriculum of the discipline "Occupational safety in industry and civil protection." While performing this laboratory work, the student should familiarize himself with the requirements regarding the electromagnetic field and control the voltage levels at the workplaces. Based on the obtained results, the student must draw a conclusion regarding the possibility or impossibility of working in such conditions, as well as develop measures and means to achieve regulatory parameters.&#x0D; The purpose of this article is to highlight the main possibilities of using a virtual laboratory stand to perform laboratory work on the topic "Research and assessment of the electromagnetic field at workplaces" from the normative discipline "Occupational safety in the industry and civil protection".&#x0D; The article provides an overview of windows and instructions for using the developed computer program for a virtual laboratory stand. The key features of this program are described, such as the availability of theoretical materials on the performance of laboratory work, detailed reproduction of the appearance and control elements of real equipment, the implementation of mathematical models of dependencies between input and output parameters, the ability to return to any stage of the performance of this laboratory work and continue it from any point, as well as the ability to save the results as a text file for preparing a report.&#x0D; It was established that the use of similar technologies from other laboratory works in the discipline "Occupational safety in the industry and civil protection" require further research.

Impression Disinfection and Its Effect on Dimensional Accuracy and Surface Detail in the Times of COVID-19: An In Vitro Study.

Introduction The disinfection of impressions is crucial to eliminate the viral and other microbial loads to prevent the cross contamination of diseases. The aim of this study was to compare the effect of different virucidal disinfecting methods on the dimensional accuracy and surface detail reproduction (SDR) of impression materials. Methods A total of 160 samples were fabricated with different impression materials using zinc oxide eugenol (Group 1), alginate (Group 2), polyether (Group 3), and addition silicone (Group 4) impression materials, each containing 40 samples (n=40). These groups were further divided into Subgroups A, B, C, and D (n=10) based on the disinfecting method used. Disinfection was carried outusing 0.2% peracetic acid (A), a natural polymer of glucosamine (B), ultraviolet (UV) radiation (C), and ozonated water (D). The disinfected impressions were poured in type IV gypsum, and the obtained casts were checked for dimensional accuracy and surface detail reproduction (SDR). For dimensional accuracy, a one-way analysis of variance (ANOVA) test and, for surface detail reproduction, the chi-square test were used to compare the different subgroups of each impression material separately. Results Zinc oxide eugenol samples showed the lowest mean dimensional change when disinfected with 0.2% peracetic acid (1A=154.1 µm), and alginate showed the lowest mean dimensional change when disinfected using ozonated water (2D=134.9 µm). On the other hand, the lowest mean dimensional change observed in polyether and addition silicone samples was those which were disinfected using UV radiation (3C=100.9 µm and 4C=113.5 µm). Surface detail was reproduced adequately in most of the samples. Conclusion A 0.2% peracetic acid could be used to disinfect zinc oxide eugenol impressions, ozonated water for alginate impressions, and UV radiation for polyether and addition silicone impressions.

Measurement of proton induced absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from 16O(p,p ′γ )16O reaction

In this article, we report the absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from the 16O(p,p ′γ )16O reaction for incident proton energy range of 8-16 MeV. Angular distributions of the three γ-rays have been measured for seven angles at 9 MeV proton energy. A detailed phenomenological optical model potential (OMP) was set up to analyse the cross-section data. The OMP parameters were optimised using elastic, polarization and total reaction data available in the literature for protons and neutrons. Low-lying states of 16O were coupled, the optical potential was deformed using deformation parameters, and several resonances were included in the calculations to account for the nuclear structure effects. The potentials so generated have been used to calculate the differential and total cross sections for both 16O(p,p ′ )16O and 16O(p,p ′γ )16O reactions. Our calculated cross-sections are in fairly good agreement with our measured data for 6.13, 6.92 and 7.12 MeV γ-rays. However, there still exist discrepancies in reproduction of the finer details of the cross sections. The comparisons of the calculations with the data bring forth the rather complex roles of channel couplings, resonances in the p+16O system and target deformation in the variation of the cross sections with projectile energy. The increased contribution of nuclear structure effects in light mass nuclei, leads to an apparent loss of predictive power of the theoretical calculation, as we approach the low-energy region of less than 10 MeV projectile energy.

Comparison of Some Properties between Commercially Available Gypsum Products

Gypsum models are often used in dental healthcare, and there is an increased need for manipulation of master casts in extensive reconstructions requi ring a material that is not easily abraded or damaged with dimensional accuracy, accurate reproduction of details, and the use of a voids free surface master model. This study was conducted to compare between commercially available type III and type IV dental stones in some of their properties. Four groups were compared: Zhermack and Geastone of Type III dental stone, and Zhermack and Bluejey of Type IV improved dental stone. Ten specimens were fabricated for each material from a rubber ring w ith dimensions of 20mm height and 30mm diameter. Dimensional stability, reproduction of details, surface porosity, and surface hardness were evaluated for the different gypsum products. Results of this study show that for the dimensional stability there was an increase in dimension more than that of the test block and was only highly significant for groups Z3 and Z4. The surface hardness for groups Z3 and Z4 was significant higher than groups G3 and B4 in all of time intervals except after 24h for groups Z4 and B4 this was insignificant. Surface porosity test and reproduction of details test, both revealed no significant difference between the test groups. As conclusion the Zhermack dental stone products, type III &amp; IV, showed higher surface hardness than Zeus dental stone products, type III &amp; IV (Geastone and Bluejey). On the other hand we found that Zeus dental stone products showed good dimensional stability than the Zhermack dental stone products. All stone products provided similar scores for details reproduction, and were similar in relation to surface porosity.

Three-dimensional printed models as an effective tool for the management of complex congenital heart disease.

Three-dimensional printed models are widely used in the medical field for surgical and interventional planning. In the context of complex cardiovascular defects such as pediatric congenital heart diseases (CHDs), the adoption of 3D printed models could be an effective tool to improve decision-making. In this paper, an investigation was conducted into the characteristics of 3D printed models and their added value in understanding and managing complex pediatric congenital heart disease, also considering the associated cost. Volumetric MRI and CT images of subjects with complex CHDs were retrospectively segmented, and the associated 3D models were reconstructed. Different 3D printing technologies and materials were evaluated to obtain the 3D printed models of cardiac structures. An evaluation of time and costs associated with the 3D printing procedure was also provided. A two-level 3D printed model assessment was carried out to investigate the most suitable 3D printing technology for the management of complex CHDs and the effectiveness of 3D printed models in the pre-surgical planning and surgical strategies' simulations. Among the different techniques, selective laser sintering resulted to be the most suitable due to its reduced time and cost and for the positive clinical feedback (procedure simulation, surface finish, and reproduction of details). The adoption of 3D printed models contributes as an effective tool in the management of complex CHDs, enabling planning and simulations of surgical procedures in a safer way.

Recent advances of 3D-printing in spine surgery.

The emerging use of three-dimensional printing (3DP) offers improved surgical planning and personalized care. The use of 3DP technology in spinal surgery has several common applications, including models for preoperative planning, biomodels, surgical guides, implants, and teaching tools. A literature review was conducted to examine the current use of 3DP technology in spinal surgery and identify the challenges and limitations associated with its adoption. The review reveals that while 3DP technology offers the benefits of enhanced stability, improved surgical outcomes, and the feasibility of patient-specific solutions in spinal surgeries, several challenges remain significant impediments to widespread adoption. The obvious expected limitation is the high cost associated with implementing and maintaining a 3DP facility and creating customized patient-specific implants. Technological limitations, including the variability between medical imaging and en vivo surgical anatomy, along with the reproduction of intricate high-fidelity anatomical detail, pose additional challenges. Finally, the lack of comprehensive clinical monitoring, inadequate sample sizes, and high-quality scientific evidence all limit our understanding of the full scope of 3DP's utility in spinal surgery and preclude widespread adoption and implementation. Despite the obvious challenges and limitations, ongoing research and development efforts are expected to address these issues, improving the accessibility and efficacy of 3DP technology in spinal surgeries. With further advancements, 3DP technology has the potential to revolutionize spinal surgery by providing personalized implants and precise surgical planning, ultimately improving patient outcomes and surgical efficiency.

Dynamic response analysis of the TetraSpar floater in waves: Experiment and numerical reproduction

The initial proof of concept model scale test campaign for the TetraSpar floating wind turbine substructure is presented here along with a detailed response analysis and numerical reproduction. The tests were conducted at scale 1:60 in wind and waves with the pitch-regulated DTU 10 MW wind turbine. The floater was tested in two configurations: semi-submersible and spar. The experimental setup and program is described in detail followed by system identification for natural frequencies and damping. The responses of the floater in the two configurations to hydrodynamic loading are analysed and compared. The analysis includes irregular sea states and focused wave groups at both 0° and 30° heading. The hydrodynamic damping of the floaters was quantified in decay tests, showing a clear linear and second-order component. It was observed that the semi-submersible configuration had significantly larger motion response than the spar configuration in ultimate limit state wave conditions. Emphasis is placed on the mooring loads and the tensions in the support lines for the ballasted keel. The increased ballast of the spar keel led to larger loads in these support lines. Further, second- and higher-order wave forcing were observed in responses of both configurations. A numerical model based on first-order radiation-diffraction theory, second-order Newman loads and additional Morison viscous forcing is set up. The model damping is calibrated against the measurements at each sea state. It is demonstrated that after this calibration, the model is able to reproduce the floater response and tower top accelerations with good accuracy, both in the linear range and at the natural floater frequencies, with heave in the storm sea state as the exception. The dynamic tensions in the keel lines are found to depend strongly on the lines projection to the inline wave direction. Also this behaviour is reproduced accurately by the model, although with some under-prediction in one of the lines in the rated wind sea state, which is linked to differences in the experimental pre-tension for the six lines.

Effect of Adding some Additives and Drying Method on Compressive Strength of Gypsum Products

Gypsum products (dental plaster and stone) are widely used in dentistry. However, the main problem with any gypsum products is reproduction of fine details and dimensional stability. The current study was conducted to assess the effect of incorporating various additives (i.e. cured resin, pulverised stone, pulverised plaster, and glass fibers) and drying method on compressive strength of gypsum products. A total of 160 specimens were divided into 2 groups according to the method of drying (air and microwave). For each drying method, each group was subdivided depending on the type of material used into 2 groups; dental plaster and dental stone. Variuos additives were used for reinforcement; cured resin, pulverised plaster, pulverised stone, and glass fibers. The unmodified group was considered as control. The specimens were dried and the compressive strength test was applied on all specimens. All specimens' data were statistically analysed via ANOVA, Tukey and independent T tests.The compressive strength of gypsum products was significantly influenced by the type of additive used. The specimens reinforced with glass fibers, cured resin, pulverised plaster, and stone had a greater value of mean compressive strength compared with unmodified groups. Statistically, highly significant differences were observed among all dried groups (P≤0.001). As well, the microwave specimens were more resistant to compressive loadings than air dried specimens. No significant differences, however, were recorded between the two drying methods (P&gt;0.05).The glass fibers have a significant effect on compressive strength of gypsum products. The pulverised particles and cured resin can be added at 1 % by weight to enhance the mechanical properties of plaster and stone. Microwave drying for 5 minutes can fasten the drying time and permit early manipulation of plaster and stone models.

Antimicrobial Efficiency of Hypochlorous Acid and Its Effect on Some Properties of Alginate Impression Material.

Dental clinicians and professionals need an affordable, nontoxic, and effective disinfectant against infectious microorganisms when dealing with the contaminated dental impressions. This study evaluated the efficiency of hypochlorous acid (HOCl) as an antimicrobial disinfectant by spraying technique for the alginate impression materials, compared with sodium hypochlorite, and its effect on dimensional stability and reproduction of details. HOCl with a concentration of 200 ppm for 5 and 10 min was compared with the control group (no treatment) as a negative control and with sodium hypochlorite (% 0.5) as a positive control. Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa were selected to assess the antimicrobial activity with the colony forming unit test in addition to the dimensional stability and reproduction of details tests. The results revealed that HOCl had significant antimicrobial activity against all tested microorganisms and experimental time. Interestingly, HOCl showed no impact on the dimensional stability of alginate impression material. HOCl could be an effective antimicrobial agent for alginate impression material without interfering with their surface details and dimensional stability.