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Density Functional Theory Calculation of Band Gap of Iron (II) disulfide and Tellurium
Get PDFIn this work, the band gap of Iron(II) disulfide and Tellurium were computed using the density functional theory with different meta-GGA functionals. The results showed that the meta-GGA functional M06L gave the closest value of the band gap as 0.96 eV compared to the experimental value of 0.95 eV for Iron(II) disulfide while the meta-GGA functional BJ06 gave the closest value of the band gap as 0.339 eV compared to the experimental value of 0.335 eV for Tellurium. This study showed that the meta-GGA functionals M06L and BJ06 can effectively predict the band gap of Iron(II)disulfide and Tellurium. In general, the use of meta-GGA functionals can be extended to compute the band gap of other semiconductors
Gingival Recession in Orthodontics: A Review
Get PDFBy clinical definition, gingival recession refers to the exposure of the root surface by an apical shift in the position of the gingiva. Recession is important because it can lead to poor esthetics, tooth hypersensitivity, loss of periodontal support, difficulties in maintenance of oral hygiene, and increased susceptibility to caries. Although its etiology is not fully understood, periodontal disease and mechanical trauma are considered the primary factors in the pathogenesis of gingival recession. Orthodontic treatment might also promote the development of gingival recessions. It has been well established that orthodontic forces can move roots close to or through the alveolar cortical plates, leading to bone dehiscence. In such instances, the marginal gingiva, without proper alveolar bone support, might be expected to migrate apically and lead to root exposure. This assumption is based on the fact that in areas of recession, a subjacent alveolar bone dehiscence is always present
A Summary of Current Research on the Functional Morphology of Flight in Azhdarchid Pterosaurs
Get PDFAzhdarchid pterosaurs existed during the Mesozoic era and died out during the mass extinction at the end of the Cretaceous. These amazingly large creatures have sparked a debate on whether they were capable of flying or simply gliding due to their massive size, anatomy and morphology. Two theories that have been developed are that these creatures were terrestrial stalkers and that they are closer to pelicans in terms of feeding capability. More specifically, Naish and Witton suggest that these giants were capable of covering large distances by soaring and could forage on land by walking quadrupedally using their long necks to reach down and kill small animals, parts of dead tissues and possibly fruits. Fossil evidence to support this theory includes tracks of the Azhdarchid’s showing a parasagittal gait, a winged planform, and specimens have been only found in continental depositional settings. Evidence also indicates that these creatures had membranes serving as wings, but it cannot be discerned with current knowledge whether membranes were used for gliding or for true flying
Novel Prototype of Mining Helmet to Facilitate Cooling
Get PDFThe thermal comfort of mining helmet during mining process is important as it can affect the physiological and psychological condition of the worker. Project deals with the development of cooling system for mining helmet using powerful fan technology. The system consists of mainly two fans and batteries. Electrical power is used to run the fan, which creates a temperature difference inside the helmet and facilitates cooling. Fans are used to suck the air from the surrounding and air is circulated inside the helmet and provides a soothing cool breeze inside the helmet. The numerical and experimental results indicate that the temperature inside the helmet can be reduced by 4-5 0C in approximately 3-4 minutes in the mining helmet
Exploring the Dialectical Relationship between National Discourse and the Family in a Contemporary World
Get PDFNational discourse can be described as any conversation that permeates the generality of a nation. Being the most basic unit of a nation, the centrality of the family to the continuous existence of a nation cannot be overemphasised. This centrality is reflected in how the national discourse of a nation descends to the family, and how events in the family can trigger a national discourse. Predicated on the discourse theory, and using the discourse analysis method to examine purposively selected cases that underpinned national discourses in Nigeria and the United States, the paper examined the symbiotic relationship between national discourse and the family being the smallest unit of a nation. It was discovered that the relationship between national discourse and the family is dialectical, which calls for consciousness on the part of every individual in the family, the media and the nation at large, especially in how national discourses are triggered
Progress and Prospect on Stability of Perovskite Photovoltaics
Get PDFSolar energy has the potential to solve world energy problem as it is pollution- free. It could be enhanced using perovskite material as an absorber in perovskite solar cells. The history and what this material is made up of are emphasized. Different methods of fabrication, improving the power conversion efficiency (PCE) and factors influencing degradation of perovskite-based solar are stated. Because of the fact that this material based solar cells are not yet developed, its stability was reviewed to bring different technology employed in tackling the stability aiming for a better understanding of the material and the devices and facilitates the commercialization of perovskite solar cell
Password Based Distribution Panel and Circuit Breaker Operation for the Safety of Lineman during Maintenance Work
Get PDFSecurity is the prime concern in our day to day life while performing any activity. In the current scenario, accidental death of lineman is often read and evidenced. In this direction, a safety measure to safe guard the operator is found very necessary looking into the present working style. The electric lineman safety system is designed to control the control panel doors and circuit breaker by using a password for the safety. Critical electrical accidents to lineman are on the rise during electric line repair may be due to lack of communication and co-ordination between the maintenance staff and electric substation staff. The proposed system provides a solution that ensures safety of lineman. The control to turn ON or OFF the line is maintained by the lineman. The system has an arrangement such that a password is required to operate the doors of the control panel and circuit breaker (ON/OFF). A secured password is requested and received from the control room by the lineman for the point of repair or service. This request is registered and a password is sent to the lineman’s mobile and control panel GSM module for the further work. The password is entered through the matrix keypad which is interfaced to the Arduino Uno microcontroller. The entered password is compared with the password received by the control panel GSM receiver. If the entered password is correct then the circuit breaker ON/OFF and door OPEN/CLOSE feature is enabled for the lineman to take up repair. Any intruder tries to operate the mechanism with the wrong password by three times it will display a message in the LCD display and a message is sent to the control room regarding unauthorized accessing of the system for the safety reasons
Synthesis, Characterization and Properties of MgB2 Doped Polyaniline
Get PDFPresent paper reports novel synthesis of MgB2 doped Polyaniline (PAni). PAni is synthesized through oxidative polymerization method using Ammonium Peroxodisulphate and doped by different compositions of MgB2. The DC conductivity of undoped and doped polymers is measured in the temperature range of 300 – 400 K and is found to increase with temperature. An increase in conductivity by five orders of magnitude has been observed after doping. Conduction mechanism was also studied in all of the samples. FT-IR (Fourier Transform Infrared spectroscopy) and Ultraviolet (UV)-Visible studies confirm the occurrence of PAni in conducting emeraldine salt form in the composites. The optical studies signify that absorption mechanism is due to direct allowed transition and the band gap decrease after doping. Thermal stability of all the composites has been explained on the basis of variation in Tc–Tg and ∆Hc by using DSC (Differential Scanning Calorimetery) measurements
Color Origins in Langatate Crystals
Get PDFLangatate La3Ga5.5Ta0.5O14 is piezoelectric crystal from langasite family, commonly grown by Czochralski method from Ir crucible. Langatate crystals of different colors (colorless, orange, green) have been studied by optical spectroscopy in UV-Visible (200 – 800 nm) and IR (7000 – 1000 cm-1) ranges. Furthermore, the effects of irradiation by ultraviolet laser source (λ=266 nm) and post-growth annealing in N2+O2 atmosphere have been investigated. The yellow-orange is mainly due to an absorption centered in the ultraviolet that extends into the blue of the visible spectrum (250-500 nm). The IR optical absorption spectra of Langatate crystals exhibit an absorption band at 5370 cm-1. It seems linked to a point defect responsible for color. The intensity of the absorption band at 3430 cm-1 increases after annealing in oxygen containing atmosphere. We have discussed phenomenon that can occur simultaneously in langatate crystals and produce very similar colors which are related to structural defects. First, metal ions impurities (as Iron, Titanium…), whose presence is previously confirmed by femtosecond laser ablation coupled with ICP-MS spectroscopy, can contribute to langatate color. Second, ultraviolet absorption leads us to think about charge transfer phenomenon such as O2- → Fe3+ and/or Fe3+-Fe3+ pair transitions. Third, the irradiation by ultraviolet (λ=266 nm) laser source locally color the langatate sample by the creation of color centers. Origins of color centers, particularly those related to oxygen vacancies, ( , 2e′)x, are discussed. And, finally, point defects changes the band gap of langatate, leading to extend the absorption to visible light regions
Pro-embrionary Somatic Structure of Three Cacao Genotypes (Theobroma Cacao l.) Using Staminodes
Get PDFStaminodes of three cocoa genotypes (BT1, ICS-39 and CCN-51), were used to perform the characterization of somatic embryos induced and maintained by DKW culture medium enriched with 2% of sucrose, 10% of coconut water and 0.01% of cysteine, 2,5 mg/l 2,4 D, 5 µg/lTDZ respectively. The ANOVA and the comparison mean test, shown significant differences between globular-, heart-, torpedo- and cotyledonal-stages for each genotype. Additionally, the embryogenic stages and regenerants plants proportions were highest for Blanco Tarapotino 1 (BT1) genotype. A morphological comparison of somatic and zygotic embryos shows similarities in form and symmetry