Search results for "BAND"
showing 10 items of 2610 documents
Silver Sulfide Nanoclusters and the Superatom Model
2015
The superatom model of electron-shell closings has been widely used to explain the stability of noble-metal nanoclusters of few nanometers, including thiolate-protected Au and Ag nanoclusters. The presence of core sulfur atoms in silver sulfide (Ag–S) nanoclusters renders them a class of clusters with distinctive properties as compared to typical noble-metal clusters. Here, it is natural to ask whether the superatom model is still applicable for the Ag–S nanoclusters with mixed metal and nonmetal core atoms. To address this question, we applied density functional simulations to analyze a series of Ag–S nanoclusters: Ag14S(SPh)12(PPh3)8, Ag14(SC6H3F2)12(PPh3)8, Ag70S16(SPh)34(PhCO2)4(triphos…
Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition.
2013
A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near th…
Atomic layer deposition of AlN from AlCl3 using NH3 and Ar/NH3 plasma
2018
The atomic layer deposition (ALD) of AlN from AlCl3 was investigated using a thermal process with NH3 and a plasma-enhanced (PE)ALD process with Ar/NH3 plasma. The growth was limited in the thermal process by the low reactivity of NH3, and impractically long pulses were required to reach saturation. Despite the plasma activation, the growth per cycle in the PEALD process was lower than that in the thermal process (0.4A ° vs 0.7A ° ). However, the plasma process resulted in a lower concentration of impurities in the films compared to the thermal process. Both the thermal and plasma processes yielded crystalline films; however, the degree of crystallinity was higher in the plasma process. The…
Kontrabanda organizētā grupā
2016
Bakalaura darba tēma ir “Kontrabanda organizētā grupā”. Darba mērķis ir pētīt kontrabandas noziedzīgus nodarījumus, kas pastrādāti organizētā grupā Krimināllikuma 190.panta izpratnē (ar grozījumiem, kas stājās spēkā ar 2015.gada 3.decembri). Aplūkot kontrabandas rašanās vēsturi, sākot no 1903.gada līdz mūsdienām. Izpētīt tās attīstību un problemātiku, mainoties politiskai un ekonomiskai situācijai. Autore veiks kontrabandas pamatsastāva un kvalificējošo pazīmju analīzi. Mēģinās izprast kontrabandas krimināltiesisko atbildību un tās atšķirību no administratīvā pārkāpuma. Darbā tiks veikts kontrabandas jēdziena salīdzinājums ar ārvalstu krimināltiesībām.
Organizētas grupas izpratne teorijā un praksē
2016
Bakalaura darba mērķis – izpētīt organizētas grupas jēdziena teorētisko izpratni un piemērošanas praksi Latvijā. Lai sasniegtu mērķi, tika izvirzīti šādi uzdevumi: atrast, iepazīties, apkopot, izanalizēt vajadzīgo informāciju par teorētisko pamatu organizētas grupas konstatēšanai; iepazīties ar Latvijas tiesu praksi attiecīgajā jautājumā, iepazīties ar ārvalstu pieredzi un krimināllikumiem; iepazīties ar organizētas noziedzības vēsturi Latvijā un ārvalstīs. Bakalaura darba izstrādes rezultātā izvirzīts priekšlikums par nepieciešamību atgriezties pie brīvāka regulējuma soda noteikšanai par organizētā grupā izdarītajiem noziegumiem un tiesnešu izglītošanai par aktuālajām problēmām praksē orga…
A retrospective transversal study of enlargement and college dropout
2006
At present leaving and prolonging studies constitutes a serious problem at the university level. This report pre-sents the results of a retrospective transversal study which purpose was to identify risk factors related with dropout. The methodology design used can be for help
Application of Broadband Dielectric Spectroscopy to Cultural Heritage: characterization and preservation of ancient paper artwork
2016
Within the cultural heritage the characterization and conservation of artworks based on paper represents a significant issue for both restorers and scientists. The paper deterioration is affected by the degree of hydrolytic and oxidative reactions which occur upon aging. Moreover, the durability of cellulose fibers depends on the intrinsic composition/structure of the paper as well as on the conservation conditions, such as temperature and humidity. The structural and dynamical characterization of the cellulose matrix and of the water confined within its pores is therefore of central interest. Our working hypothesis is that WATER DYNAMICS is one of the main determinants of paper degradation…
Compromiso Estudiantil en el Contexto Universitario Colombiano y Desempeño Académico
2014
20 páginas A pesar de la ampliación de la cobertura en la educación superior latinoamericana, persisten graves problemas de deserción que llevan a cuestionar el papel de las experiencias educativas en el fomento del compromiso académico de los estudiantes. Esta investigación se realizó en Colombia y buscó determinar la relación que existe entre el compromiso estudiantil y el desempeño académico de un grupo de universitarios colombianos. El estudio transversal y correlacional empleó la versión en español de la encuesta National Survey of Student Engagement (NSSE) que mide el nivel de participación de los estudiantes en cinco dimensiones: reto académico, aprendizaje activo y colaborativo, int…
La ciencia ficción y la enseñanza de las ciencias
2012
Este trabajo constituye una primera aproximación a la ciencia en la ciencia ficción desde el punto de vista del alumnado y qué posibilidades ofrece como recurso didáctico. Sondeamos, por tanto, si los alumnos conocen y han visto cine de ciencia ficción, así como si este factor influye en sus actitudes hacia la ciencia y los científicos y su opinión sobre las consecuencias de los avances científicos en el futuro. Asimismo, nos planteamos si los estudiantes perciben las visiones deformadas de la ciencia y los científicos que transmite el cine de ciencia ficción. Pretendemos, asimismo, estudiar si se utiliza la ciencia ficción como recurso didáctico.
Technical English for agriculture
2021
As the world goes global, the agricultural business needs to move across frontiers and oceans. Food, raw and processed, is regularly transported across continents. As space is no longer a limit for food trade and human nutrition, language cannot represent a barrier to this continuous exchange. In the last 60 years, English has been taking a foothold as the primary language for world trade and the exchange of agricultural goods is no exception. Agricultural sciences embrace a large number of disciplines, from botany to environmental physiology, from soil science to meteorology, from plant propagation to cultural management, from soil management to pest control, from field crops to animal husb…