The motivation of this study is to promote sustainability in the construction and mining industries from a research perspective, considering the CO2 emissions associated with cement production and the use of mining waste materials, such as copper tailings, as supplementary cementitious materials. In this study, copper tailings partially replaced cement as received between 0 to 50 wt.%. Mortar and reinforced mortar samples were manufactured for mechanical and corrosion analysis. The mechanical tests revealed that the maximum compressive and flexion strengths were maintained by adding copper tailings, which were delayed for a longer exposure time, possibly due to the hydration reaction. Morphological analysis revealed that the partial cement replacement increased the porosity in the mortar at earlier stages, which was similar for longer exposure time. In addition, electrochemical impedance spectroscopy allowed in-situ monitoring of the mortar\'s evolution and mortar/steel interface. The impedance response showed that partial cement replacement with 15 wt. % of copper tailings as received can improve steel passivation after prolonged exposure. Therefore, cement replacements can be a suitable solution to produce reinforced mortars.
This systematic review and meta-analysis aimed to assess the impact of contamination with eugenol-containing or eugenol-free temporary cement on the bond strength of self-adhesive resin cement. A comprehensive electronic search was conducted across Pubmed, Scopus, and ISI databases without language or publication date restrictions, up to August 18, 2020. Eligible studies were in vitro investigations measuring the bond strength of self-adhesive cement after contamination with eugenol-free or eugenol-containing provisional cement. Articles were categorized based on the type of temporary cement (with or without eugenol), and the effect size was presented as the standardized difference in means (SDM) between the intervention and control groups. A random-effects model was employed for the meta-analysis. Out of 450 initially identified articles, four met the inclusion criteria. The results indicated a significant reduction in the bond strength of self-adhesive cement when the temporary restoration was adhered with either eugenol-containing (SDM = -1.64, P < 0.001, I2 = 48.48%) or eugenol-free (SDM = -1.33, P < 0.001, I2 = 61.68%) provisional cement, compared to the control group. Contamination with temporary cement, regardless of eugenol presence, diminishes the bond strength of self-adhesive cement. It appears that the residue of temporary cement is a more critical factor than the presence or absence of eugenol in weakening the bonding quality of permanent cement to the tooth substrate.
Space colonisation will depend on our capacity to sustain a crew\'s metabolic demands (food, water, and oxygen) on a regular basis with little to no replenishment from Earth. Plant crops are cultivated on earth to support these tasks, hence developing plant-based food production systems is crucial in maintaining humankind\'s existence in space. For thousands of years, farming methods have changed on Earth to satisfy the needs of a growing population and the scarcity of resources. Currently, these methods need to change to account for the effects of global warming. Space farming is the practice of cultivating crops for food and other uses in space or on alien planets. Food supply to space stations and other long-term missions requires a lot of labour and money. The cost of refilling and the difficulties of resupplying interplanetary trips make the idea of manufacturing food in flight quite appealing. To supply water, nutrients, and oxygen to the plant roots, specialised space greenhouses use controlled release fertiliser, a porous clay base, and LED illumination. Comprehending the growth responses of plants to space-specific restrictions including changed gravity, ionising radiation, and constrained volume is essential, in addition to understanding the growth responses to all environmental elements that act on Earth. It is also necessary to modify farming methods in light of these constraints. The nature and degree of environmental aspects that need to be considered are contingent upon the specific mission situations. This paper deals with the historical perspective, need and basic concepts of space farming. It also provides insights on the impacts of space factors on plants and types of space farms.
Titanium dioxide films of different thicknesses, ranging from 10 to 110 nm were deposited on glass substrate, at room temperature by physical vapor deposition method. Topography, roughness and crystallography of produced layers were determined by AFM and XRD methods respectively. Optical properties were measured by transmission spectroscopy in the spectral range of 300-1100 nm wave length range. The optical constants were obtained using Kramers-Kronig analysis of the reflectivity curves. It was found that film thickness plays an important role on the nanostructures as well as optical properties of layers and cause significant variations in behavior of thin titanium oxide films.
Principle role of a Power System Stabilizer (PSS) is to increase damping of oscillations of generator rotor by control of its excitation by using of auxiliary stabilizer signals. The design of a PSS can be performed by suitable state and optimum feedback that roots of case study is transferred to suitable points as designed results. As the large searching techniques, Genetic Algorithms (GA) is global search techniques to provide a powerful tool for optimization problems by optimizing the mechanisms of natural selection and genetics. To fast accessing of desired results, this paper used a modified Genetic Algorithm for suitable designing of stabilizer. Finally, the advantages of the proposed method are illustrated by numerical simulation of the one machines-infinite-bus power systems.
The present study basically deals with the construction of the small pond in particular and the water filtration in general in Choghazanbil which is considered the valuable memorial of Ilam civilization constructed near Susa, Khouzestan. According to the reliable views, there are two hypotheses about this small pond. 1. The existence of multiple drain pipes shows that Ilamian paid attention to the necessity of protection system and water discharging with regard to the material quality and the weather of that time 2. When the bigger pond became full of water and the water level became on the same level with the margin of its ending wall, according to the related containers rules, the water\'s mires will sediment. In this study, with physical considerations, the potential capability of the pond to produce high quality water is proved. According to historical states of Choghazanbil site and archeology excavations; with combining two hypotheses, the real performance of two ponds is filtering discharged surface waters
While discussion of employees empowerment has been prevalent in the popular literature for many years, theoretical research on psychological empowerment has been appearing only recently in scholarly journals. Empowerment is a concept that links individual strengths and competencies, natural helping systems and proactive behaviour to social policy and social change. On the other hand, critical success factors (CSFs) have been used significantly to present or identify a few key factors that organisations should focus on to be successful. This paper aims to identify a new framework for determining critical success factors towards evaluating the activities of employees’ empowerment process. The case study of this research is Tehran Municipality. The study consisted of 200 employees and managers of that participated in the survey. For data analysis SPSS18.0 and LISREL8.7 has been used. To meet the research basic purpose, a new model containing 5 big factors has been presented. Then based on this model, 19 factors have been indentified that were the main critical success factors that appropriate for evaluating the activities of empowering employees process.
In recent years, information and knowledge are replacing capital and energy as the wealth- creating assets, just as the latter to replaced land and labour 200 years ago. The increased prominence of knowledge related economics from the beginning of the 1990,s have coexisted with the development of the new view on business strategy that emphasizes resource efficiency rather than the generally accepted competitive forces. Organizations are implementing knowledge management (KM) systems with the assumption that the result will be an increase in organizational effectiveness, efficiency, and competitiveness. Practices of knowledge management are context-specific and they can influence organizational effectiveness. Using the lessons learned from early adopters, many organizations have effectively provided their employees with the tools they need for managing and sharing knowledge. In the e-economy era, for achieve and sustain the competitive advantage, the implementation of strategic knowledge management (SKM) is undeniable. Through knowledge driven reconfiguration, integration and innovation of organizational competencies, are gained. And consequently knowledge oriented organizational subsystems, provide the basis for strategic knowledge management enabling competencies to combine their knowledge on markets and products to gain sustainable competitive advantage. The main purpose of this research is to identify the critical success factors (CSFs) that are very important for SKM implementation. For this purpose data was gathered from services sector of Iran and with focus on the biggest part of this services sector that is banking industry. Data was gathered from both academicians and professionals of the field. After appropriate literature review and also data that gathered from the research population through a question, data was analyzed and eventually the more important critical success factors for SKM implementation in this sector was identified and presented. Also the structural equation modelling has been run to demonstrate the validity of basic CSFs in this research. In the final section of this paper the both applied and theoretical recommendations are presented.
A simple, highly sensitive, accurate and selective method for determination of trace amounts of Pb(II) in water samples is presented.a novel Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs) solid-phase extraction adsorbent was synthesized by covalently grafting a Schiff base-chitosan (S-CS) onto the surfaces of oxidized MWCNTs. The stability of a chemically(S-CS-MWCNTs) especially in concentrated hydrochloric acid which was then used as a recycling and pre-concentration reagent for further uses of (S-CS-MWCNTs). The method is based on selective chelation of Pb(II) on surfactant coated C18, modified with a Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs). The retained ions were then eluted with 4 ml of 4 M nitric acid and determined by flame atomic absorption spectrometry(FAAS) at 283.3 for Pb. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated C18 adsorbs 40 mg of the Schiff’s base which in turn can retain 15.0±0.9mg of each of the two ions. The limit of detection(3σ) for Pb(II) was found to be 3.20 ng l -1. The enrichment factor for both ions are 100. The mentioned method was successfully applied on determination of lead in different water samples. The ions were also speciated by means of three columns system.
Mismatch negativity (MMN) was used to investigate the processing of cluster and noncluster initial consonants in consonant-vowel syllables in the human brain. The MMN was elicited by either syllable with cluster or noncluster initial consonant, phonetic contrasts being identical in both syllables. Compared to the noncluster consonant, the cluster consonant elicited a more prominent MMN. The strong MMN peaks at ~128 ms after change onset in cluster-to-noncluster initial consonants changes and at ~212 ms in noncluster-to-cluster initial consonants changes. The significantly different neuronal populations were thus active between 128-212 ms when syllables with cluster and noncluster initial consonants were present. Microstate segmentation analyses showed that the phonological perception for cluster consonant was at 212 ms whereas 128 ms for non-cluster consonant. After approximately 220 ms, semantic perception started in order to perceive the meaning of the words.
