Effects of Space Charge, Dopants, and Strain Fields on Surfaces and Grain Boundaries in YBCO Compounds

Statistical thermodynamical and kinetically-limited models are applied to study the origin and evolution of space charges and band-bending effects at low angle [001] tilt grain boundaries in YBa$_2$Cu$_3$O$_7$ and the effects of Ca doping upon them. Atomistic simulations, using shell models of interatomic forces, are used to calculate the energetics of various relevant point defects. The intrinsic space charge profiles at ideal surfaces are calculated for two limits of oxygen contents, i.e. YBa$_2$Cu$_3$O$_6$ and YBa$_2$Cu$_3$O$_7$. At one limit, O$_6$, the system is an insulator, while at O$_7$, a metal. This is analogous to the intrinsic and doping cases of semiconductors. The site selections for doping calcium and creating holes are also investigated by calculating the heat of solution. In a continuum treatment, the volume of formation of doping calcium at Y-sites is computed. It is then applied to study the segregation of calcium ions to grain boundaries in the Y-123 compound. The influences of the segregation of calcium ions on space charge profiles are finally studied to provide one guide for understanding the improvement of transport properties by doping calcium at grain boundaries in Y-123 compound.Comment: 13 pages, 5 figure

From steam engine to solar cells: can thermodynamics guide the development of future generations of photovoltaics?

Thermodynamics has played a singular role in the development of virtually all energy technologies to-date. This review argues that it also has a role to play in the understanding and design of solar cell operation, particularly looking toward the future, high-efficiency solar cells. After a historical overview of the key developments in the ‘thermodynamics of light,’ the conversion of a monochromatic light beam is used as a starting point to analyze the conversion process, examine the fundamental losses in terms of irreversible entropy generation, and consider in detail one of the key applications: the Shockley–Queisser detailed balance. We review and compare the principal suggestions for the highest theoretical efficiency of solar energy conversion, and analyze one possible embodiment of such a third-generation structure: the hot-carrier solar cell. A somewhat different application of the statistical approach—light trapping—is reviewed at a fundamental level, and the future potential is considered for devices which combine such a ‘thermodynamic squeezing’ of light with latest developments in photonics, leading to a photonic bandgap solar cell. We argue that the widespread use of thermodynamic tools in the current photovoltaics research, especially when combined with the potential benefits to future devices, already indicates that our thinking should not be about if but how thermodynamics can guide us to make better solar cells

Silver(I) sulfide: Ag2S Heat capacity from 5 to 1000 K, thermodynamic properties, and transitions

The heat capacity of Ag2S has been measured by adiabatic-shield calorimetry from 5 to 1000 K. The heat capacity increases regularly up to about 445 K where the pre-transitional contribution causes rapidly rising values. The [alpha]-to-[beta] transition of Ag2S occurs in the range 449.3 to 451.3 K, depending upon previous history of the sample. The enthalpy of transition [Delta]trsHm = (4058+/-26) J[middle dot]mol-1. A slightly decreasing heat capacity is observed for [beta]-Ag2S from 88.1 J[middle dot]K-1[middle dot]mol-1 at 460 K to 85.0 J[middle dot]K-1[middle dot]mol-1 at 850 K with a minimum of 84.6 J[middle dot]K-1[middle dot]mol-1 at 750 K. The transition of [beta]-Ag2S to [gamma]-Ag2S occurs at about 865 K with [Delta]trsHm = (784+/-5) J[middle dot]mol-1. Thermodynamic functions have been evaluated and the values of Cp,m, "Smo(T)-Smo(0)', and -"Gmo(T)-Hmo(0)'/T at 298.15 K are 75.31, 142.89, 85.43, and at 1000 K are 80.57, 253.28, 172.77 J[middle dot]K-1[middle dot]mol-1, respectively. No signs of further transitions were found, either in the stoichiometric compound, or in a sample with overall composition Ag2S1.0526. Thus, the present work does not support the hypothesis of Perrott and Fletcher concerning partial disordering of stoichiometric Ag2S around 600 K as opposed to complete disordering around 450 K in the presence of excess silver or sulfur. Subtraction of the estimated lattice heat capacity at constant pressure leaves a large transitional heat capacity for [beta]-Ag2S above 450 K. It is about 11 J[middle dot]K-1[middle dot]mol-1 at 500 K and decreases gradually to about 6 J[middle dot]K-1[middle dot]mol-1 at 850 K. Its origin is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26409/1/0000496.pd

Time of primar rehabilitation and care by patients with fracture of proximal femure

The topic of the thesis I chose on the basis of their interest in the subject orthopedics . Fractures of the proximal femur fractures are among the most common and most serious. Incidence with us around 50 to 60 to l00 000 inhabitants a rising trend. Surely it plays an important role increasing middle life expectancy. (14) Fractures of the femoral neck and intertrochanteric fractures occur virtually same frequency . The average age of patients with fractures of the proximal femur is 77 years and the proportion of women and men is 3:1 ( 14). Intertrochanteric fractures that represent about 10 % of fractures of the proximal femur have two peaks occurrence , between 20-40 years and in patients over 60 years old . In younger arise as result of high energy trauma in the elderly etiology is the same as the cause of other fractures of the proximal femur. The mechanism of injury is the most direct impact on the trochanter during a fall to the side or limb external rotation during the fall forward. (14) For the treatment of hip fractures osteosynthesis or prosthesis use . The method of choice in the treatment of trochanteric fracture osteosynthesis . (15) The aim of this work was to evaluate patients treated at the Orthopedic - Traumatology Clinic of the Faculty Hospital in Prague for fracture the proximal femur in..

Development of Web Applications for Operation on Mobile Phones

This thesis discusses workflow and technologies used to create mobile web apps. The thesis focuses mainly on web for touch devices. First part of this work describes differences between mobile phones and personal computers. These differences are compared mainly in task of ergonomic use and technological limits for mobile web browsing. It also discusses common problems of web for mobile devices. Main part of this thesis shows workflow of using technology and design principles for creating mobile web. It discusses patterns for proper graphic design which improves ergonomic use of web on mobile devices. The thesis also shows some software technologies used to developing mobile web. It also compares differences between native and mobile apps and shows some utilities for creating native apps using web technologies. The end of work is shown example of creating native app and different approaches of creating mobile web apps

Comparison of interaction between the teacher and student during the individual teaching of downhill skiing

Title: Comparison of interaction between the teacher and student during the individual teaching of downhill skiing. Objectives: The main aim of this thesis is to compare the interaction between the ski instructors and preschool children during the individual lessons of downhill skiing in the ski school. Methods: As the method of the comparison was used the method of observation with utilization of categorial system M ADI (Modificated analysis of didactic interaction). This system makes it possible to obtain data, which describes the forms of behaviour of a teacher, didactic content of teaching, didactic situation and attitudinal activity. Results: The result of the comparison is a fact that the instructor number 5 differed from others the most. These differences were the most apparent in the form of behaviour, form of display and its kind and measure of expression of subject content. Instructor number 5 did not respect didactic principles, styles, methods and procedures and she did other didactic mistakes. It was found out, that the practical experience is a premise for a quality teaching, but on the other hand it's not the decisive factor. Keywords: M ADI, ADI, ski school, individual lesson of skiing, preschool ag

Synchronizing JavaScript object between clients and server

The thesis deals with methods of real-time data synchronization among multiple clients. The thesis focuses on methods in collaborative RIA systems running on the Internet This methods solve data transfer and conflict resolution caused by competitive clients work on one document. The introduction describes two methods: an established Operational transformation method and the new Differential synchronization method. The thesis describes the principles of both methods and their advantages and disadvantages. The aim of the work is implementing and comparison of Differential Synchronization method with Operational transformation method. These methods are compared in Node.js environment of JavaScript programming language and it is compared their performance in terms of response time and resource requirements. It's identified a problems associated with the method implementations in Node.js and it is described solutions of this problems. In the practical part thesis focus on the describing of performance data and behave of methods during measurement and refuted or confirmed the premises of methods definition assumptions. The Differential Synchronization method is extended by some parts based on the author often criticized issues of method