Search results for: light transmittance

Authors: Christina Eleftheria Tzeliou, Demeter Tzeli

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Introduction: Molecular Logic Gates (MLGs) are molecular machines that can perform complex work, such as solving logic operations. Molecular switches, which are molecules that can experience chemical changes are examples of successful types of MLGs. Recently, Quintana-Romero and Ariza-Castolo studied experimentally six stable pseudo-hemi-indigo-derived MLGs capable of solving complex logic operations. The MLG design relies on a molecular switch that experiences Z and E isomerism, thus the molecular switch's axis has to be a double bond. The hemi-indigo structure was preferred for the assembly of molecular switches due to its interaction with visible light. Z and E pseudo-hemi-indigo isomers can also be utilized for selective isomerization as they have distinct absorption spectra. Methodology: Here, the photophysical properties of pseudo-hemi-indigo derivatives are examined, i.e., derivatives of molecule 1 with anthracene, naphthalene, phenanthrene, pyrene, and pyrrole. In conjunction with some trials that were conducted, the level of theory mentioned subsequently was determined. The structures under study were optimized in both cis and trans conformations at the PBE0/6-31G(d,p) level of theory. The absorption spectra of the structures were calculated at PBE0/DEF2TZVP. In all cases, the absorption spectra of the studied systems were calculated including up to 50 singlet- and triplet-spin excited electronic states. Transition states (cis → cis, cis → trans, and trans → trans) were obtained in cases where it was possible, with PBE0/6-31G(d,p) for the optimization of the transition states and PBE0/DEF2TZVP for the respective absorption spectra. Emission spectra were obtained for the first singlet state of each molecule in cis both and trans conformations in PBE0/DEF2TZVP as well. All studies were performed in chloroform solvent that was added as a dielectric constant and the polarizable continuum model was also employed. Findings: Shifts of up to 25 nm are observed in the absorption spectra due to cis-trans isomerization, while the transition state is shifted up to about 150 nm. The electron density distribution is also examined, where charge transfer and electron transfer phenomena are observed regarding the three excitations of interest, i.e., H-1 → L, H → L and H → L+1. Emission spectra calculations were also carried out at PBE0/DEF2TZVP for the complete investigation of these molecules. Using protonation as input, selected molecules act as MLGs. Conclusion: Theoretical data so far indicate that both cis-trans isomerization, and cis-cis and trans-trans conformer isomerization affect the UV-visible absorption and emission spectra. Specifically, shifts of up to 30 nm are observed, while the transition state is shifted up to about 150 nm in cis-cis isomerization. The computational data obtained are in agreement with available experimental data, which have predicted that the pyrrole derivative is a MLG at 445 nm and 400 nm using protonation as input, while the anthracene derivative is a MLG that operates at 445 nm using protonation as input. Finally, it was found that selected molecules are candidates as MLG using protonation and light as inputs. These MLGs could be used as chemical sensors or as particular intracellular indicators, among several other applications. Acknowledgements: The author acknowledges the Hellenic Foundation for Research and Innovation for the financial support of this project (Fellowship Number: 21006).

Keywords: absorption spectra, DFT calculations, isomerization, molecular logic gates

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Authors: D. Zujur, J. Moret, D. Rodriguez, L. Cruz, J. Lira, L. Gil, E. Dominguez, J. F. Alvarez-Barreto

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In this work, chitosan (CH) has been used to produce a novel coating for Ti6Al4V, the most widely used alloy in orthopedic implants, so as to improve the biological tissue response at the metallic surface. The Ti6Al4V surface was sandblasted with alumina particles and observed by SEM. Chitosan was chemically modified, via crodiimide chemistry, with lactobionic and 4-azidebenzoic acid to make it soluble at physiological pH and photo-crosslinkable, respectively. The reaction was verified by FTIR, NMR, and UV/vis spectroscopy. Ti6Al4V surfaces were coated with solutions of the modified CH and exposed to UV light, causing the polymer crosslinking, and formation of a hydrogel on the surface. The crosslinking reaction was monitored by FTIR at different exposure times. Coating morphology was observed by SEM. The coating´s cytocompatibility was determined in vitro through the culture of rat bone marrow´s mesenchymal stem cells, using an MTT assay. The results show that the developed coating is cytocompatible, easy to apply and could be used for further studies in the encapsulation of bioactive molecules to improve osteogenic potential at the tissue-implant interface.

Keywords: chitosan, photo-crosslinking, Ti6Al4V, bioactive coating, hydrogel

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Authors: Sampriti Panda

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Earning one’s own livelihood is the most basic and inseparable activity for survival and existence of humankind. In any kind of situation and in every type of geographical terrain, human does adopt various strategies and ways of earning their own livelihood. Since time immemorial, anthropocentrism has been the saga of livelihood where environment is out casted and exploited to any limit so that mankind can survive. With the passage of time, humans regained their consciousness and realized that the time has arrived now to shift to sustainable livelihood and stop being self centered. This paper tries to focus on the very central issue and the hotpot of discussion in the present era which revolves around sustainable livelihood. The aim of the paper is to find out how the tribal communities which are primarily forest based are the best example of sustainable livelihood since their existence. The paper also tries to throw light on the burning issue of the so-called term ‘development’ affecting the traditional ways of livelihood opted by the forest based tribal communities. The data presented in the paper are primary and have been collected using various techniques and methodology like observation, interviews, life histories, case studies and other techniques used in a self conducted fieldwork among the Juangs, who are one of the PVTGs of Odisha.

Keywords: forest, livelihood, sustainability, tribe

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Authors: Loizos A. Hadjivasiliou, May Chehab

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Confronted with the human tragedy unfolding in the Mediterranean during the 2011-2016 period, the European Union introduced for the first time the “hotspot approach”, the establishment of facilities for initial reception, identification registration, and fingerprinting of asylum seekers and migrants arriving in the EU by sea, at the frontline Member States. However, the lack of a comprehensive collective policy on migration management and border security left the Mediterranean Member States, mainly Italy, Greece, and Cyprus, struggling to overcome these challenges. The current study sheds light on the implementation of the hotspot approach as the frontispiece of the European response to the migration challenges, which, limited to the operational and financial support of the hosting member states, leads to heterogeneous burden-sharing. Within this framework, it highlights the fact that the implementation of the hotspots as a panacea carries the risk of transforming the Mediterranean member states into giant hotspots with unpredictable consequences for the future of the Schengen area.

Keywords: asylum, burden sharing, hotspots, migration management policy, Schengen area

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Authors: Othman Ali Alghtani, Yahya Abdul-Ekhalq Ali, Abdullah Abdul-Ekhalq Ali, Ahmed Al Sadiq Abdul Majeed, Najwa Attian Al-Mohammadi, Obead Mozel Alharbi, Sabri Mohamed Ismail, Omar Ibrahim Asiri

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This study assessed the curricula of secondary schools given requirements to enhance the quality of life of students. The components of quality of life were described to build a list of standards and indicators. A questionnaire assessing the dimensions of mental (cognitive and emotional), physical, digital, and social health, and environmental awareness was prepared. A descriptive-analytical approach was used on a sample of 258 teachers and educational supervisors in Tabuk. The results indicated shortcomings in the secondary school curricula regarding developing standards and indicators of components of quality of life. Results also indicated that secondary school curricula incorporated few practices to improve student’s quality of life. No significant differences were found regarding the core subject, job, gender, and years of experience.

Keywords: assessing curricula, teacher practices, quality of life, teaching practices

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Authors: Sozan H. Omar, Luluah A. Al Jabr

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The current study aimed to identify critical thinking skills and its level of inclusion in all the activities (44) listed in 11th grade chemistry textbooks. The researcher used a descriptive analytical method by using the content analyzing design. An instrument was created for this purpose and tested for validity and reliability. Results showed that, all activities included critical thinking skills with different ratios as follow: conclusion skill was (87.72%), induction skill was (80.90%), interpretation skill was (77. 72%), discussion of evaluation skill was (68.64%), and assumption skill was (50.45%). Also, the study results indicated that, the level of inclusion of critical thinking skills in the scientific activities was more explicit than implicit with same order as the level of inclusions. In the light of the study's results, the researcher provided some recommendations including the need to provide and redistribute critical thinking skills in the activities listed the chemistry textbook, as well as the need to pay attention to the inclusion level of these skills more implicitly in the activities.

Keywords: critical thinking skills, chemistry textbooks, scientific activities

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Authors: Mohammad Saleem, Mujahid Kamran

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It is shown that causality, the principle that cause must precede effect, leads inter alia, to highly significant result that the velocity of a material particle cannot be even equal to that of light. Consequently, combined with special relativity, it leads to the conclusion that material particles of zero rest mass cannot exist in nature. Thus, causality, a principle without which nature would be incomprehensible, combined with special relativity, forbids the existence of material particles of zero rest mass. For instance, the neutrinos, as is now known, are material particles of non-zero rest mass. The situation changes when we consider the gauge particles. In fact, when the principle of causality was proposed, the concept of gauge particles had not yet been introduced. Now we know that photon, a gauge particle with zero rest mass does exist in nature. Therefore, principle of causality, as generally stated, is valid only for material particles. For gauge particles, in order to make the statement of causality consistent with experiment, it has to be modified: The cause should either precede or be simultaneous with the effect. Combined with special relativity, it allows gauge particles of zero rest mass.

Keywords: causality, gauge particles, material particles, special relativity

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Authors: M. Heysem Arslan, Ikilem Gocek, U. Kivanc Sahin

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Natural dyestuff, extracted from Juglans Regia L., a kind of walnut, was used to dye 100% cotton gabardine fabric. The main goal of this study was to enhance dyeing process of cotton fabric with Juglans Regia L. dyestuff in terms of color fastness values by designing and developing a mordant application process. Within the context of this study, different mordants such as tannic acid, gallic acid, ascorbic acid, potassium sodium tartrate tetrahydrate, calcium carbonate, iron (II) sulphate heptahydrate, aluminum potassium sulphate dodecahydrate and their combinations were applied in the mordanting processes. Spectrophotometric analysis, color fastness to washing and color fastness to light tests were carried out on the fabric samples. In this study, it was shown that by using the right combination of mordants with a proper application process, it is possible to improve color fastness values of cotton fabric samples dyed with natural dyestuff.

Keywords: extraction, Juglans Regia L., mordanting process, natural dyestuff

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Authors: Nizar Souiden, Riadh Ladhari

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Like tobacco and alcohol, recreational marijuana falls under the umbrella of ‘sin’ industries’. Notwithstanding this general negative image surrounding marijuana use, some scholars argue that most of the widely believed claims made about recreational marijuana users are irrelevant and that marijuana use can even improve individuals’ decision-making. This study intends to shed light on this particular product category (i.e., marijuana) often overlooked or portrayed as taboo from a business view. More specifically, it investigates whether legalizing the consumption of recreational marijuana would be perceived as ethical and whether companies/organizations involved in the commercialization of this particular product would be held socially responsible. Based on primary data collected in Canada, this study aims to answer the following questions: 1) What moral thoughts do individuals hold with regard to the consumption of recreational marijuana? 2) How do these moral thoughts determine consumers’ attitude toward the consumption of recreational marijuana? Regardless of the legalization of recreational marijuana in some countries such as Canada, probing people’s opinions, and investigating their attitudes toward the consumption of recreational marijuana is of important interest to different stakeholders such as consumers, public organizations, private businesses, and trade associations.

Keywords: recreational marijuana, moral thoughts, ethics, attitude

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Authors: Khalid Ishola Bello

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Many religions and cultures believe in the existence of invisible beings who co-exist with man on earth. Muslims, for example, believe in malaikah (Angel) and jinn (demon), who have their source of creation from light and flame, respectively. Jinn, according to Islamic texts, possesses unique characteristics which give them an advantage over the man. Invisibility, transforming into or taking possession of another being are parts of advantages jinn have above man. Hence, jinn can attack man and truncate his well-being by causing malfunction of his physiological and psychological realms, which may go beyond physical health care. It is on this background that this paper aims to articulate the possibility of a demonic attack on human health and the care processes recommended by Islam to heal and restore well-being of the victim. Through analysis of the inductive, deductive, and historical approaches, the process of ruqyah (healing method based on recitation of the Qur’an) and hijamah (cupping) therapies shall be analyzed. The finding shows the efficacy of Islamic remedies to demonic possession, which usually complicates health challenges in the care of man. This alternative approach is therefore recommended for holistic health care since physical health care cannot fix spiritual health challenges.

Keywords: wellbeing, healthcare, demonic possession, cupping, jinn

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Authors: Cesar Maximo Oliva González, Javier Acevedo Cortez, Boris Kharisov, Thelma Serrano Quezada

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The importance of the crude oil refining process is due to the demand for petroleum products such as gasoline, kerosene, asphalt, etc., which are used in daily activities and have a high impact on the global economy. In the processes of oil obtaining and refining, it is common to find problems such as spills on seabed and high energy consumption in processing. In order to quickly and efficiently attack these problems, the use of adsorbents has taken on great importance due to its ease of implementation, as well as the possibility of their regeneration to be reused. In this work, the use of two types of adsorbents is proposed: the first is a natural adsorbent such as aloe vera or nopal, which were lyophilized and hydrophobized to achieve a selectivity in oil adsorption in oil / water mixtures. The second is a mixed iron/nickel oxide, which is specially designed to adsorb the asphaltenes in the heavy fractions of the oil; in addition, this type of adsorbents presents catalytic properties that manage to decompose the heavier fractions of the petroleum in light hydrocarbons, descending thus the energy required for the oil refining process.

Keywords: nanomaterials, oil spills, remediation, natural adsorbents, mixed oxides

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Authors: Ali Kara, Asim Olgun, Sevgi Sozugecer, Sahin Ozel, Kubra Nur Yildiz, P. Sevinç, Abdurrahman Kuresh, Guliz Turhan, Duygu Gulgun

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The synthetic dyes, one of the most hazardous chemical compound classes, are important potential water pollutions since their presence in water bodies reduces light penetration, precluding the photosynthesis of aqueous flora and causing various diseases. Some the synthetic dyes are highly toxic and/or carcinogenic, and their biodegradation can produce even more toxic aromatic amines. The adsorption procedure is one of the most effective means of removing synthetic dye pollutants, and has been described in a number of previous studies by using the functional polymers. In this study, we investigated the removal of synthetic dyes from aqueous solution by using a functional polymer as an adsorbent material. The effect of initial solution concentration, pH, and contact time on the adsorption capacity of the adsorbent were studied in details. The results showed that functional polymer has a potential to be used as cost-effective and efficient adsorbent for the treatment of aqueous solutions from textile industries.

Keywords: functional polymers, synhetic dyes, adsorption, physicochemical parameters

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Authors: Kelemewerk Destalem, Joongjae Cho, Jaeseong Lee, Ju H. Park, Joonhyuk Yoo

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Background subtraction and temporal difference are often used for moving object detection in video. Both approaches are computationally simple and easy to be deployed in real-time image processing. However, while the background subtraction is highly sensitive to dynamic background and illumination changes, the temporal difference approach is poor at extracting relevant pixels of the moving object and at detecting the stopped or slowly moving objects in the scene. In this paper, we propose a moving object detection scheme based on adaptive background subtraction and temporal difference exploiting dynamic background updates. The proposed technique consists of a histogram equalization, a linear combination of background and temporal difference, followed by the novel frame-based and pixel-based background updating techniques. Finally, morphological operations are applied to the output images. Experimental results show that the proposed algorithm can solve the drawbacks of both background subtraction and temporal difference methods and can provide better performance than that of each method.

Keywords: background subtraction, background updating, real time, light weight algorithm, temporal difference

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Authors: Munnujahan Ara

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In this paper, we investigate the effect of friendly jamming power allocation strategies on the achievable average secrecy rate over a bank of parallel fading wiretap channels. We investigate the achievable average secrecy rate in parallel fading wiretap channels subject to Rayleigh and Rician fading. The achievable average secrecy rate, due to the presence of a line-of-sight component in the jammer channel is also evaluated. Moreover, we study the detrimental effect of correlation across the parallel sub-channels, and evaluate the corresponding decrease in the achievable average secrecy rate for the various fading configurations. We also investigate the tradeoff between the transmission power and the jamming power for a fixed total power budget. Our results, which are applicable to current orthogonal frequency division multiplexing (OFDM) communications systems, shed further light on the achievable average secrecy rates over a bank of parallel fading channels in the presence of friendly jammers.

Keywords: fading parallel channels, wire-tap channel, OFDM, secrecy capacity, power allocation

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Authors: Delele Worku Ayele, Bing-Joe Hwang

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A method that does not employ hot injection techniques has been developed for the size-tunable synthesis of high-quality CdSe quantum dots (QDs) with a zinc blende structure. In this environmentally benign synthetic route, which uses relatively less toxic precursors, solvents, and capping ligands, CdSe QDs that absorb visible light are obtained. The size of the as-prepared CdSe QDs and, thus, their optical properties can be manipulated by changing the microwave reaction conditions. The QDs are characterized by XRD, TEM, UV-vis, FTIR, time-resolved fluorescence spectroscopy, and fluorescence spectrophotometry. In this approach, the reaction is conducted in open air and at a much lower temperature than in hot injection techniques. The use of microwaves in this process allows for a highly reproducible and effective synthesis protocol that is fully adaptable for mass production and can be easily employed to synthesize a variety of semiconductor QDs with the desired properties. The possible application of the as-prepared CdSe QDs has been also assessed using deposition on TiO2 films.

Keywords: average life time, CdSe QDs, microwave (MW), mass production oleic acid, Na2SeSO3

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Authors: Ilan Tamir

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Fans’ chants in sports stadium have, over the years, become an integral part of the spectator experience. While chants add color, atmosphere, and a demonstration of fans’ support for their team, chants also play a significant role in defining fans’ perceptions of their team’s identity and its differentiation from other teams. An analysis of football chants may therefore shed light on fans’ deep-seated worldviews of their own role, their team, the sport in general, and even life itself. This study, based on an analysis of Israeli football chants over years, identifies key changing and stable perceptions of football fans. Overall 94 chants collected, over a period of five decades. After a pilot study, the chants organized in two groups (one covering 1970-1999 and the other 2000-2016). The chants analyzed through qualitative content analysis in order to understand fans values as a reflection of the society. Findings point to several values that have remained stable over years, including fans’ attitudes toward their team and its rivals, and their attitude toward God. On the other hand, recently emerging phenomena such as radicalization of hatred toward the commercialization of sport reflect social and cultural changes, both in and outside the world of sport.

Keywords: sport, fans, chants, soccer

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Authors: Alok Kumar Pasa, Krs Raghavan

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This paper presents a comparative analysis of Brushless DC (BLDC) motors for flywheel applications with a focus on the choice of stator core materials. The study employs a Finite Element Method (FEM) in time domain to investigate the performance characteristics of BLDC motors equipped with nonmagnetic and magnetic type stator core materials. Preliminary results reveal significant differences in motor efficiency, torque production, and electromagnetic properties between the two configurations. This research sheds light on the advantages of utilizing nonmagnetic materials in BLDC motors for flywheel applications, offering potential advantages in terms of efficiency, weight reduction and cost-effectiveness.

Keywords: finite element time stepping method, high-speed BLDC motor, flywheel energy storage system, coreless BLDC motors

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Authors: Vidit Mohan, Ashwin P. Ramesh, Anirudh Toshniwal

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Alkali-Surfactant-Alternate-Gas(ASAG) injection, a novel EOR process has the potential to improve displacement efficiency over Surfactant-Alternate-Gas(SAG) by addressing the problem of surfactant adsorption by clay minerals in rock matrix. A detailed laboratory investigation on ASAG injection process was carried out with encouraging results. To further enhance recovery over WAG injection process, SAG injection was investigated at laboratory scale. SAG injection yielded marginal incremental displacement efficiency over WAG process. On investigation, it was found that, clay minerals in rock matrix adsorbed the surfactants and were detrimental for SAG process. Hence, ASAG injection was conceptualized using alkali as a clay stabilizer. The experiment of ASAG injection with surfactant concentration of 5000 ppm and alkali concentration of 0.5 weight% yields incremental displacement efficiency of 5.42% over WAG process. The ASAG injection is a new process and has potential to enhance efficiency of WAG/SAG injection process.

Keywords: alkali surfactant alternate gas (ASAG), surfactant alternate gas (SAG), laboratory investigation, EOR process

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Authors: Farzad Vakili-Farahani, Joern Lungershausen, Kilian Wasmer

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Wobbled laser beam welding, fast oscillations of a tiny laser beam within a designed path (weld geometry) during the laser pulse illumination, opens new possibilities to improve the marco-to micro-manufacturing process. The present work introduces the wobbled laser beam welding as a robust welding strategy for improving macro-to micro-fabrication process, e.g., the laser processing for gap-bridging and packaging industry. The typical requisites and relevant equipment for the development of a wobbled laser processing unit are addressed, including a suitable laser source, light delivery system, optics, proper beam deflection system and the design geometry. In addition, experiments have been carried out on titanium plate to compare the results of wobbled laser welding with conventional pulsed laser welding. As compared to the pulsed laser welding, the wobbled laser welding offers a much greater fusion area (i.e. additional molten material) while minimizing the HAZ and provides a better confinement of the material microstructural changes.

Keywords: wobbled laser beam welding, wobbling function, beam oscillation, micro welding

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Authors: Ezgi Cetinkaya

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In the psychological literature, there are a few studies that focus on actors' self-perceptions and their social adjustment skills. Therefore the aim of the study was to shed light on the self-concept clarity, sociotrophy, and self-monitoring levels of professional actors. For this purpose, actors and non-actors are compared to their peers. The study was conducted with the participation of 106 actors and 131 non-actors. A descriptive method of research was employed and data was collected through the concept Clarity scale by Campbell et al. (1996), the Pleasing Others and Concern For Disapproval subscales of Sociotrophy and Autonomy scale by Beck et al. (1983), and the Self-Monitoring Scale by Snyder ( 1983). ANOVA and correlation analysis was done by using SPSS. Results showed that there is no significant difference between actors and non-actors at any age in terms of Self Concept Clarity. 25-25 years non-actors were found to have the highest self-concept clarity while the young actors had the lowest. The study didn’t reveal significant differences between the groups in terms of Sociotropy scores. The actor’s sociothropic tendencies weren’t enhanced by the experience. The study demonstrated that 25-35-year-old actors are higher self-monitors than 25-35-year-old non-actors.

Keywords: self-concept, self-monitoring, autonomy, sociotropy, theatre, acting, creativity, identity

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Authors: Sarah Akhtar, Rizwan Mahmood

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A detailed study of homogeneous alignment of liquid crystal molecules on a glass substrate will be presented. Thin films of polyimide were coated on several glass substrates. Various methods were employed to prepare coated surfaces to achieve desired alignment; these include traditionally rubbing the surface with a felt cloth then exposing them perpendicular to the easy axis with incandescent light (IL), linearly polarized ultraviolet (LPUVR) and un-polarized ultraviolet (UPUVR) radiation. The quality of the alignment was tested by measuring the tilt angle in the temperature range between 30°C to 55°C. Regression analysis of the data using ‘SigmaPlot’ suggests a gradual increase in tilt angle (1.1°-1.8°) for the rubbed, 0.6° to 3.6° increase for the rubbed plus IL radiated and 1.6° to 4.6° for the rubbed plus UPUVL radiated samples, respectively. However to our surprise, we found tilt angle to be decreasing from 2.4° to 1.6° for the rubbed plus LPUVL radiated samples. We hope that these findings will be helpful in the fabrication of display panels and other electro-optic devices.

Keywords: homogeneous, liquid crystals, polyimide, tilt angle

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Authors: Sherry Robinson, Hans Anton Stubberud

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Entrepreneurship can take many forms. Traditional entrepreneurs seek profits and growth for the businesses they start themselves. Intrapreneurs act entrepreneurially within a business they do not own. Social entrepreneurs have goals other than (but not excluding) profit and growth as they seek to solve social problems or protect the environment. This type of entrepreneur often focuses on the triple bottom line, which includes a concern for people and the planet as well as profit. Ecopreneurs in particular are driven by their desire to create and promote environmentally sustainable products and processes. All of these entrepreneurs need an entrepreneurial orientation in order to survive and thrive. The three most common elements of an entrepreneurial orientation are (1) creativity and innovation, (2) the willingness to take risks and (3) the proactiveness to put ideas into action. This study describes an interdisciplinary entrepreneurship course integrating topics regarding the triple bottom line with those relevant to an entrepreneurial orientation. The results show that students significantly increased their skill levels in many areas, including soft skills such as communicating and working in teams, as well as designing innovative products and taking calculated risk.

Keywords: creativity, entrepreneurship education, sustainability, triple bottom line

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Authors: Essam Shalaby, Alexander Churyumov, Malak Abou El-Khair, Atef Daoud

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A comparative study of the thermal and mechanical behavior of squeezed A359 composites containing 5, 10 and 15 wt.% SiC, (SiC+ Si3N4) and AlN particulates was investigated. Stir followed by squeeze casting techniques are used to produce A359 composites. It was noticed that, A359/AlN composites have high thermal conductivity as compared to A359 alloy and even to A359/SiC or A359/(SiC+Si3N4) composites. Microstructures of the composites have shown homogeneous and even distribution of reinforcements within the matrix. Interfacial reactions between particles and matrix were investigated using X-ray diffraction and energy dispersive X-ray analysis. The presence of particles led not only to increase peak hardness of the composites but also to accelerate the aging kinetics. As compared with A359 matrix alloy, compression test of the composites has exhibited a significant increase in the yield and the ultimate compressive strengths with a relative reduction in the failure strain. Those light weight composites have a high potential to be used for automotive and aerospace applications.

Keywords: metal-matrix composite, squeeze, microstructure, thermal conductivity, compressive properties

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Authors: Byung Cheol Kim

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The Program Evaluation and Review Technique (PERT) is widely used for project management, but it struggles with subjective distributions, particularly due to its assumptions of constant variance and light tails. To overcome these limitations, we propose the Generalized PERT (G-PERT) model, which enhances PERT by incorporating variability in three-point subjective estimates. Our methodology extends the original PERT model to cover the full range of unimodal beta distributions, enabling the model to handle thick-tailed distributions and offering formulas for computing mean and variance. This maintains the simplicity of PERT while providing a more accurate depiction of uncertainty. Our empirical analysis demonstrates that the G-PERT model significantly improves performance, particularly when dealing with heavy-tail subjective distributions. In comparative assessments with alternative models such as triangular and lognormal distributions, G-PERT shows superior accuracy and flexibility. These results suggest that G-PERT offers a more robust solution for project estimation while still retaining the user-friendliness of the classic PERT approach.

Keywords: PERT, subjective distribution, project management, flexible variance

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Authors: Abderrahmane Hamdi, Julie Chalon, Benoit Dodin, Philippe Champagne

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This research work concerns the synthesis of hydrophobic and self-cleaning coatings as an alternative to fluorine-based coatings used on glass. The developed, highly transparent coatings are produced by a chemical route (sol-gel method) using two silica-based precursors, hexamethyldisilazane and tetraethoxysilane (HMDS/TEOS). The addition of zinc oxide nanoparticles (ZnO NPs) within the gel provides a photocatalytic property to the final coating. The prepared gels were deposited on glass slides using different methods. The properties of the coatings were characterized by optical microscopy, scanning electron microscopy, UV-VIS-NIR spectrophotometer, and water contact angle method. The results show that the obtained coatings are homogeneous and have a hydrophobic character. In particular, after thermal treatment, the HMDS/TEOS@ZnO charged gel deposited on glass constitutes a coating capable of degrading methylene blue (MB) under UV irradiation. Optical transmission reaches more than 90% in most of the visible light spectrum. Synthetized coatings have also demonstrated their mechanical durability and self-cleaning ability.

Keywords: coating, durability, hydrophobicity, sol-gel, self-cleaning, transparence

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Authors: Eun Ju Park, Wendy Rusli, He Tao, Alexander M. Van Herk, Sanggu Kim

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Hollow micro-/nano- structured materials have proven to be promising in wide range of applications, such as catalysis, drug delivery and controlled release, biotechnology, and personal and consumer care. Hollow sphere structures can be obtained through various templating approaches; colloid templates, emulsion templates, multi-surfactant templates, and single crystal templates. Vesicles are generally the self-directed assemblies of amphiphilic molecules including cationic, anionic, and cationic surfactants in aqueous solutions. The directed silica capsule formations were performed at the surface of dioctadecyldimethylammoniumbromide(DODAB) bilayer vesicles as soft template. The size of DODAB bilayer vesicles could be tuned by extrusion of a preheated dispersion of DODAB. The synthesized hollow silica particles were characterized by conventional TEM, cryo-TEM and SEM to determine the morphology and structure of particles and dynamic light scattering (DLS) method to measure the particle size and particle size distribution.

Keywords: characterization, DODAB, hollow silica particle, synthesis, vesicle

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Authors: Kholoud Adeeb. Al-Dababneh

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This study aimed at investigating teachers' perceptions of using assistive technologies in teaching children with disabilities in Jordan. The researcher developed a study instrument (questionnaire) to examine teachers' perceptions regarding the use of assistive technologies in teaching children with disabilities. The validity and reliability of the research instrument were checked. A random sample of 260 teachers who teach children with disabilities participated in the study by completing the questionnaire; fifteen teachers were later interviewed. Results revealed that the use of assistive technology by teachers in teaching children with disabilities was high. The results also revealed that there are statistically significant differences at (α= .05) according to the type of disability in favor of teachers of children with specific learning disabilities (SLD), according to educational settings in favor of local public schools (inclusion settings). The results revealed that there were no statistically significant differences attributed to the teacher's level of education and teachers' gender. In light of the study results, the researcher addressed several recommendations and future implications.

Keywords: assistive technologies, children with disabilities, Jordan, teachers

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Authors: George R. Mawhinney

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In 2003 Parliament passed statutory sentencing guidelines, the only of their kind, for the sentencing of murder in England and Wales, after the Home Secretary's role in determining sentences for the offence was effectively ended by the House of Lords' decision in Anderson applying Art.6 of the ECHR (European Convention on Human Rights). However, in the parliamentary debates during the passage of the Criminal Justice Act 2003 containing the guidelines, many views were expressed both by government ministers and backbench MPs of various parties concerning the gravity of the offence of murder, principally discussing the harm of death. This paper examines parliamentary debates as recorded in Hansard, to assess whether this was isolated or indeed there was a broader movement at the time to treat the harm of death more seriously by toughening sentencing regimes for other related homicide offences, or even creating new offences concerning the causing of death. Such evidence of valuing the harm of death more seriously than before would shine a new light on what previously has been deemed mere 'popular punitiveness' and offer a principled basis for lengthening the sentences of these kind of crimes.

Keywords: death, desert, gravity, harm, murder, parliamentary intention, Schedule 21, sentencing, seriousness

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Authors: K. S. Sruthi

Abstract:

Antennas are one of the most important parts of a communication chain. They are used for both communication and calibration purposes. New developments in probe technologies have enabled near-field probes with much larger bandwidth. The objective of this paper is to design, simulate and fabricate a dual polarized wide band inverted quad ridged shape horn antenna which can be used as measurement probe for near field measurements. The inverted quad-ridged horn antenna probe not only provides measurement in the much wider range but also provides dual-polarization measurement thus enabling antenna developers to measure UWB, UHF, VHF antennas more precisely and at lower cost. The antenna is designed to meet the characteristics such as high gain, light weight, linearly polarized with suppressed side lobes for near-field measurement applications. The proposed antenna is simulated with commercially available packages such as Ansoft HFSS. The antenna gives a moderate gain over operating range while delivering a wide bandwidth.

Keywords: near-field antenna measurement, inverted quad-ridge horn antenna, wideband Antennas, dual polarized antennas, ansoft HFSS

Procedia PDF Downloads 425

Authors: Huilan Yao, Huaixin Zhang

Abstract:

Simulations of the transition flow of model propellers are important for predicting hydrodynamic performance and studying scale effects. In this paper, the transition flow of a model propeller under different loadings are simulated using a transition model provided by STAR-CCM+, and the influence of turbulence intensity (TI) on the transition, especially friction and pressure components of propeller performance, was studied. Before that, the transition model was applied to simulate the transition flow of a flat plate and an airfoil. Predicted transitions agree well with experimental results. Then, the transition model was applied for propeller simulations in open water, and the influence of TI was studied. Under the heavy and moderate loadings, thrust and torque of the propeller predicted by the transition model (different TI) and two turbulence models are very close and agree well with measurements. However, under the light loading, only the transition model with low TI predicts the most accurate results. Above all, the friction components of propeller performance predicted by the transition model with different TI have obvious difference.

Keywords: transition flow, model propellers, hydrodynamic performance, numerical simulation

Procedia PDF Downloads 263