The effect of recasting nickel chromium and cobalt chromium alloys on the quality of fixed prosthodontic devices

Base metal dental alloys are among the oldest restorative dental materials used in dentistry. They are still widely applied and are expected to remain in demand in the coming years. They demonstrate adequate properties required to meet the needs of wide and variable applications. Base metal alloys can be used alone or in combination with other dental materials to construct a dental restoration. Due to environmental and financial factors, variable practices have emerged in the processing of these alloys. Among these practices is the reuse of surplus alloys. The aim of this study was to evaluate the effect of recycling nickel-chromium and cobalt-chromium alloys on the quality of dental restorations employing a suggested test protocol where the correlation between the different factors tested was investigated. Wax patterns of different shapes were prepared for the different tests conducted. For each alloy type, five different combinations of new and surplus alloys were prepared to cast the wax patterns using an induction casting machine. Castings were subjected to different quality assessment investigations; (i) the microstructure was assessed for the presence of pores and inclusions and the chemical composition was evaluated for the amount of elements present (mass%), castings produced from new alloy were used as a control; (ii) castings were subjected to a polishing procedure simulating the technique used in dental laboratories. Surface roughness (Ra) was analysed prior to and after the polishing procedure using light profilometer; (iii) a metal to ceramic bond strength test was conducted following the requirements of ISO 9693: 2000. ISO standardised test pieces were subjected to a three-point bending test using a universal testing machine and bond strength evaluated; and (iv) ions released from castings were measured, where castings were placed into artificial saliva at pH 4 and 6 for five weeks. The mean amounts released were measured using inductively coupled plasma atomic emission spectroscopy (ICP/OES). The findings of this study imply that although microstructure and chemical composition of castings containing surplus alloy varied from those produced entirely from new alloys, these variations were not always significant and depended on the alloy type and restoration type. Surface roughness evaluation suggests that consecutive laboratory procedures, such as finishing and polishing procedures can considerably enhance surface topography of casting produced partially and entirely from surplus alloy. For the bonding test investigation, all test groups demonstrated bond strength values higher than that recommended by ISO 9693: 2000. A similar observation was documented for the ion release test; despite the increase in the amount of ions released from castings containing surplus alloys, the detected amount of ions was however very small compared to those documented in the literature. Although some of the tested characteristics of castings containing 100% recycled alloys were marginally inferior to those produced from new alloy, the former castings gave acceptable results and would be expected to function and perform appropriately in the patient’s mouth in the equivalent manner to castings produced from new alloys. However the addition of a small amount of new alloy, as low as 25%, has been shown to enhance the performance of castings compared to those containing 100% recycled alloy in the different tests conducted

Measuring Research Productivity of LIS Departments in the Middle East

The present study measures research productivity of library and Information science departments in the Middle East. Data were collected from 16 countries whose LIS departments had at least one article indexed in Clarivate Analytics Web of Science between 2014 and 2018. Journals’ Citation Report was also used to collect further data. In measuring research productivity, the number of departments’ articles indexed in the Web of Science database and the size of each department (number of faculties) is considered as output and input, respectively. Findings indicated that Bar Ilan University had the highest research productivity (3.7), followed by Shiraz University (1.17) and Haceteppe University (1.04). With respect to LIS Department Research Productivity    Occupied Palestine, Turkey, Jordan, Kuwait and Iran ranked first to fifth respectively. The results of this research not only can contribute towards identifying highly productive and influential departments, but could also lay the groundworks for a well oriented scientific policy and cooperation.https://dorl.net/dor/20.1001.1.20088302.2022.20.2.3.

Some product graphs with power dominating number at most 2

Let S be a set of vertices of a graph G. Let M[S] be the set of vertices built from the closed neighborhood N[S] of S, by iteratively applying the following propagation rule: if a vertex and all but exactly one of its neighbors are in M[S], then the remaining neighbor is also in M[S]. A set S is called a power dominating set of G if M[S]=V(G). The power domination number ¿P(G) of G is the minimum cardinality of a power dominating set. In this paper, we present some necessary conditions for two graphs G and H to satisfy 1=¿P(G*H)=2 for product graphs.Postprint (published version

Examining the Relationship between Marketing Capability and Innovation

The need for organizations to innovate comes from increasing competition and customer demands and new market areas. In today’s complex and turbulent environment the need for innovation in products and processes is widely recognised. For firms competing in a global market place, innovations play an increasingly vital role in achieving superior performance. Marketing capability is considered to be an important factor to innovation and enhance competitive advantage of firms. The present paper intended to study the relationship between marketing capability and innovation. The  study  was  conducted  through  descriptive-applied  method  and  standard  questionnaire  was  tool  of  data  collection. The statistical population included 80 managers of stone and mining industry in Isfahan that among whom 70 persons were studied as research sample using Cochran formula.  The results revealed that there is a positive and significant relationship between marketing capability and innovation

Studying the effect of manager’s Strategic Thinking on Corporate entrepreneurship

The purpose of this research is to explore the effect of managers' strategic thinking on corporate entrepreneurship. To this end, one main hypothesis and five secondary hypotheses were proposed. This study is descriptive-applicable and Lidka studies (1998) were employed to measure managers' strategic thinking and Robins and Kutler's questionnaire (1996) was used to measure corporate entrepreneurship. The statistical population included 118 managers and employees of a manufacturing company in Kermanshah industrial estate. The research sample was equal to 90 using Cochran formula. The results disclosed that managers' strategic thinking has a positive and significant effect on corporate entrepreneurship and all hypotheses were confirme

Effect of Organizational Silence on Employees’ Productivity

Productivity and development of any organization depends highly on the right application of human resources in the organization. One of the factors affecting productivity is organizational silence which has not been considered today. Since silence can has unfavorable consequences, identifying the factors and their relationship with other phenomena is important. Hence, this research tries to investigate the effect of organizational silence on human productivity. Statistical population is 25 personnel in Arak Tax Organization. Findings showed that organizational silence has a direct and negative effect on human productivity

Effect of Empowerment on Human and Social Capital

This research investigates the effect of empowerment on human and social capital. The research method is descriptive, analytical and correlational. The statistical population consists of all employees of petrochemical industry of Markazi Province. Sample size equals to 250 employees. Data collection tool is standard questionnaire which its validity was confirmed by content and construct validity and its reliability was calculated by Cronbach’ Alpha. Collected data was analyzed by LISREL software. After the analysis, all research hypotheses accepted

Sowing the wheat seeds of Afghanistan's future

Societal Impact Statement: The production and availability of food underpins societal stability. In Afghanistan, wheat is the major arable agricultural crop and source of dietary energy. The withdrawal of NATO allies and partner countries from Afghanistan presents numerous well‐documented societal and political challenges and has impacts on immediate and longer‐term food security. Conflict‐impacted irrigation infrastructure coupled with growing climate instability have also contributed markedly to reductions in current food, and specifically wheat, production. Here, we review the status of Afghan wheat improvement and propose a research agenda to support the regeneration of Afghanistan's wheat and agricultural sector. Summary: Afghanistan is a country with diverse natural ecologies in a largely arid and mountainous region. The rural sector is still considered to drive economic potential. Current social, political and economic instability along with climatic challenges are driving food and water insecurity in the wider region. In the short term, it is likely that this and the associated challenges of displacement and unemployment can only be addressed by humanitarian intervention and agrifood and nutrition support. In the medium to long term, drought, and heat, probably linked to climate change, will pose recurrent challenges for agriculture and food security that will require a much broader set of interventions to secure the rural population's livelihoods. The genetic gap, among other major challenges, must be addressed if Afghanistan is to develop its agricultural potential leading to income and livelihood improvements for farmers and stable and accessible supplies for consumers. Only thereby will the country be enabled to reap the important and long‐sought trade and food security benefits derived from self‐sufficiency. Here, we highlight the agricultural challenges facing Afghanistan and propose forward strategies for ensuring the future stability of wheat production, the cornerstone of Afghan agriculture