Search results for: disadvantages

Authors: Nélio Veiga, Paula Ferreira, Tiago Correia, Maria J. Correia, Carlos Pereira, Odete Amaral, Ilídio J. Correia

Abstract:

Introduction: The application of fissure sealants is considered to be an important primary prevention method used in dental medicine. However, the formation of microleakage gaps between tooth enamel and the fissure sealant applied is one of the most common reasons of dental caries development in teeth with fissure sealants. The association between various dental biomaterials may limit the major disadvantages and limitations of biomaterials functioning in a complementary manner. The present study consists in the incorporation of a cariostatic agent – silver diamine fluoride (SDF) – in a resin-based fissure sealant followed by the study of release kinetics by spectrophotometry analysis of the association between both biomaterials and assessment of the inhibitory effect on the growth of the reference bacterial strain Streptococcus mutans (S. mutans) in an in vitro study. Materials and Methods: An experimental in vitro study was designed consisting in the entrapment of SDF (Cariestop^® 12% and 30%) into a commercially available fissure sealant (Fissurit^®), by photopolymerization and photocrosslinking. The same sealant, without SDF was used as a negative control. The effect of the sealants on the growth of S. mutans was determined by the presence of bacterial inhibitory halos in the cultures at the end of the incubation period. In order to confirm the absence of bacteria in the surface of the materials, Scanning Electron Microscopy (SEM) characterization was performed. Also, to analyze the release profile of SDF along time, spectrophotometry technique was applied. Results: The obtained results indicate that the association of SDF to a resin-based fissure sealant may be able to increase the inhibition of S. mutans growth. However, no SDF release was noticed during the in vitro release studies and no statistical significant difference was verified when comparing the inhibitory halo sizes obtained for test and control group.  Conclusions: In this study, the entrapment of SDF in the resin-based fissure sealant did not potentiate the antibacterial effect of the fissure sealant or avoid the immediate development of dental caries. The development of more laboratorial research and, afterwards, long-term clinical data are necessary in order to verify if this association between these biomaterials is effective and can be considered for being used in oral health management. Also, other methodologies for associating cariostatic agents and sealant should be addressed.

Keywords: Biomaterial, fissure sealant, primary prevention, silver diamine fluoride, S. mutans.

Authors: F. Saccucci

Abstract:

Gamification has now started to take root in the post-secondary classroom. Educators have learned much about gamification to date but there is still a great deal to learn. One definition of gamification is the ability to engage post-secondary students with games that are fun and correlate to class room curriculum. There is no shortage of literature illustrating the advantages of gamification in the class room. This study is an extension of similar thought as well as an extension of a previous study where in class testing proved with the used of paired T-test that gamification did significantly improve the students’ understanding of subject material. Gamification itself in the class room can range from high end computer simulated software to paper based games of which both have advantages and disadvantages. This analysis used a paper based game to highlight certain qualitative advantages of gamification. The paper based game in this analysis was inexpensive, required low preparation time for the faculty member and consumed approximately 20 minutes of class room time. Data for the study was collected through in class student feedback surveys and narrative from the faculty member moderating the game. Students were randomly selected into groups of four. Qualitative advantages identified in this analysis included: 1. Students had a chance to meet, connect and know other students. 2. Students enjoyed the gamification process given there was a sense of fun and competition. 3. The post assessment that followed the simulation game was not part of their grade calculation therefore it was an opportunity to participate in a low risk activity whereby students could subsequently self-assess their understanding of the subject material. 4. In the view of the student, content knowledge did increase after the gamification process. These qualitative advantages identified in this analysis contribute to the argument that there should be an attempt to use gamification in today’s post-secondary class room. The analysis also highlighted that eighty (80) percent of the respondents believe twenty minutes devoted to the gamification process was appropriate, however twenty (20) percentage of respondents believed that rather than scheduling a gamification process and its post quiz in the last week, a review for the final exam may have been more useful. An additional study to this hopes to determine if the scheduling of the gamification had any correlation to a percentage of the students not wanting to be engaged in the process. As well, the additional study hopes to determine at what incremental level of time invested in class room gamification produce no material incremental benefits to the student as well as determine if any correlation exist between respondents preferring not to have it at the end of the semester to students not believing the gamification process added to the increase of their curricular knowledge.

Keywords: Gamification, inexpensive, qualitative advantages, post-secondary.

Authors: Naeleh Motamedi, Masoud Mahmoudkhan Shirazi, Nima Nouraei

Abstract:

Natural disasters, including earthquake, kill many people around the world every year. Society rescue actions, which start after the earthquake and are called LAST in abbreviation, include locating, access, stabilization and transportation. In the present article, we have studied the process of local accessibility to the injured and transporting them to health care centers. With regard the heavy traffic load due to earthquake, the destruction of connecting roads and bridges and the heavy debris in alleys and street, which put the lives of the injured and the people buried under the debris in danger, accelerating the rescue actions and facilitating the accessibilities are of great importance, obviously. Tehran, the capital of Iran, is among the crowded cities in the world and is the center of extensive economic, political, cultural and social activities. Tehran has a population of about 9.5 millions and because of the immigration of people from the surrounding cities. Furthermore, considering the fact that Tehran is located on two important and large faults, a 6 Richter magnitude earthquake in this city could lead to the greatest catastrophe during the entire human history. The present study is a kind of review and a major part of the required information for it, has been obtained from libraries all of the rescue vehicles around the world, including rescue helicopters, ambulances, fire fighting vehicles and rescue boats, and their applied technology, and also the robots specifically designed for the rescue system and the advantages and disadvantages of them, have been investigated. The studies show that there is a significant relationship between the rescue team-s arrival time at the incident zone and the number of saved people; so that, if the duration of burial under debris 30 minutes, the probability of survival is %99.3, after a day is %81, after 2days is %19 and after 5days is %7.4. The exiting transport systems all have some defects. If these defects are removed, more people could be saved each hour and the preparedness against natural disasters is increased. In this study, transport system has been designed for the rescue team and the injured; which could carry the rescue team to the incident zone and the injured to the health care centers. In addition, this system is able to fly in the air and move on the earth as well; so that the destruction of roads and the heavy traffic load could not prevent the rescue team from arriving early at the incident zone. The system also has the equipment required firebird for debris removing, optimum transport of the injured and first aid.

Keywords: earthquake, accelerating, accessibilities transportation, rescue system

Authors: Arti Goel, Kanika Sharma

Abstract:

Microorganisms can be removed, inhibited or killed by physical agents, physical processes or chemical agents but they have their inherent disadvantages such as increased resistance against antibiotics etc. Since, plants have endless ability to synthesize aromatic substances which act as the master agents for plant defense mechanisms against microorganisms, insects and herbivores. Thus, secondary metabolites or phytochemicals obtained from plants can be used as agents of disease control nowadays. In the present study effect of different concentrations of acetone fraction of leaves and alcohol fraction of inflorescence of Euphorbia pulcherrima on various cytomorphological parameters i.e. cell number, mycelium width, conidial size, conidiophore size etc. of Aspergillus fumigatus has been studied. Change in mycelium/ hyphal cell width, conidium size, conidiophore size etc. was measured with the help of a previously calibrated oculometer. To study effect on morphology, fungal mycelium along with conidiophore and conidia were stained with cotton blue and mounted in lactophenol and observed microscopically. Inhibitory action of the acetone extract of Euphorbia pulcherrima leaf on growth of Aspergillus fumigatus was investigated. Control containing extract free medium supported profuse growth of the fungus. Although decrease in growth was observed even at 3.95μg/ml but significant inhibition of growth was started at7.81μg/ml concentration of the extract. Complete inhibition was observed at 15.62μg/ml and above. Microscopic examination revealed that at 3.95, 7.81 and 15.62μg/ml extract concentration hyphal cell width was found to be increased from 1.44μm in control to 3.86, 5.24 and 8.98 μm respectively giving a beaded appearance to the mycelium. Vesicle size was reduced from 24.78x20.08μm (control) to 11.34x10.06μm at 3.95μg/ml concentration. At 7.81 and 15.62μg/ml concentration no phialides and sterigmata were observed. Inhibitory action of the alcohol extract of inflorescence on the growth of Aspergillus fumigatus was also studied. Control containing extract free medium supported profuse growth of the fungus. Although decrease in growth was observed even at 3.95μg/ml but complete inhibition was observed at 62.5μg/ml and above. Microscopic examination revealed that hyphal cell width of Aspergillus fumigatus was found to be increased from 1.67μm in control to 5.84μm at MIC i.e. at 62.5μg/ml. Vesicle size was reduced from 44.76x 24.22μm (control) to 11.36x 6.80μm at 15.62μg/ml concentrations. At 31.25 μg/ml and 62.5μg/ml concentration no phialides and sterigmata was found. Spore germination was completely found to be inhibited at 3.95μg/ml concentration. Similarly 92.87% reduction in vesicle size was observed at 15.62μg/ml concentration. It is evident from the results that plant extracts inhibit fungal growth and this inhibition is concentration dependent. 

Keywords: Antimicrobial Activity, Aspergillus fumigatus, cytomorphology, Euphorbia pulcherrima.

Authors: Christian Lauter, Corin Reuter, Shuang Wu, Thomas Troester

Abstract:

Lightweight construction became more and more important over the last decades in several applications, e.g. in the automotive or aircraft sector. This is the result of economic and ecological constraints on the one hand and increasing safety and comfort requirements on the other hand. In the field of lightweight design, different approaches are used due to specific requirements towards the technical systems. The use of endless carbon fiber reinforced plastics (CFRP) offers the largest weight saving potential of sometimes more than 50% compared to conventional metal-constructions. However, there are very limited industrial applications because of the cost-intensive manufacturing of the fibers and production technologies. Other disadvantages of pure CFRP-structures affect the quality control or the damage resistance. One approach to meet these challenges is hybrid materials. This means CFRP and sheet metal are combined on a material level. Therefore, new opportunities for innovative process routes are realizable. Hybrid lightweight design results in lower costs due to an optimized material utilization and the possibility to integrate the structures in already existing production processes of automobile manufacturers. In recent and current research, the advantages of two-layered hybrid materials have been pointed out, i.e. the possibility to realize structures with tailored mechanical properties or to divide the curing cycle of the epoxy resin into two steps. Current research work at the Chair for Automotive Lightweight Design (LiA) at the Paderborn University focusses on production processes for fiber-metal-laminates. The aim of this work is the development and qualification of a large-scale production process for high-performance fiber-metal-laminates (FML) for industrial applications in the automotive or aircraft sector. Therefore, the prepreg-press-technology is used, in which pre-impregnated carbon fibers and sheet metals are formed and cured in a closed, heated mold. The investigations focus e.g. on the realization of short process chains and cycle times, on the reduction of time-consuming manual process steps, and the reduction of material costs. This paper gives an overview over the considerable steps of the production process in the beginning. Afterwards experimental results are discussed. This part concentrates on the influence of different process parameters on the mechanical properties, the laminate quality and the identification of process limits. Concluding the advantages of this technology compared to conventional FML-production-processes and other lightweight design approaches are carried out.

Keywords: Composite material, Fiber metal laminate, Lightweight construction, Prepreg press technology, Large-series production.

Authors: Alan Crowle, Philpp Thies

Abstract:

s the floating offshore wind turbine industry continues to develop and grow, the capabilities of established port facilities need to be assessed as to their ability to support the expanding construction and installation requirements. This paper assesses current infrastructure requirements and projected changes to port facilities that may be required to support the floating offshore wind industry. Understanding the infrastructure needs of the floating offshore renewable industry will help to identify the port-related requirements. Floating offshore wind turbines can be installed further out to sea and in deeper waters than traditional fixed offshore wind arrays, meaning it can take advantage of stronger winds. Separate ports are required for substructure construction, fit-out of the turbines, moorings, subsea cables and maintenance. Large areas are required for the laydown of mooring equipment, inter array cables, turbine blades and nacelles. The capabilities of established port facilities to support floating wind farms are assessed by evaluation of size of substructures, height of wind turbine with regards to the cranes for fitting of blades, distance to offshore site and offshore installation vessel characteristics. The paper will discuss the advantages and disadvantages of using large land based cranes, inshore floating crane vessels or offshore crane vessels at the fit-out port for the installation of the turbine. Water depths requirements for import of materials and export of the completed structures will be considered. There are additional costs associated with any emerging technology. However, part of the popularity of Floating Offshore Wind Turbines stems from the cost savings against permanent structures like fixed wind turbines. Floating Offshore Wind Turbine developers can benefit from lighter, more cost effective equipment which can be assembled in port and towed to site rather than relying on large, expensive installation vessels to transport and erect fixed bottom turbines. The ability to assemble Floating Offshore Wind Turbines equipment on shore means minimising highly weather dependent operations like offshore heavy lifts and assembly, saving time and costs and reducing safety risks for offshore workers. Maintenance might take place in safer onshore conditions for barges and semi submersibles. Offshore renewables, such as floating wind, can take advantage of this wealth of experience, while oil and gas operators can deploy this experience at the same time as entering the renewables space. The floating offshore wind industry is in the early stages of development and port facilities are required for substructure fabrication, turbine manufacture, turbine construction and maintenance support. The paper discusses the potential floating wind substructures as this provides a snapshot of the requirements at the present time, and potential technological developments required for commercial development. Scaling effects of demonstration-scale projects will be addressed; however the primary focus will be on commercial-scale (30+ units) device floating wind energy farms.

Keywords: Floating offshore wind turbine, port logistics, installation, construction.