Ultrasound Investigations of Orbital Quadrupolar Ordering in UPd_3

For a high-quality single crystal of UPd_3 we present the relevant elastic constants and ultrasonic attenuation data. In addition to the magnetic phase transition at T_2=4.4 +/- 0.1K and the quadrupolar transition at T_1~6.8K, we find orbital ordering at T_0=7.6 +/- 0.1K concomitant with a symmetry change from hexagonal to orthorhombic. A striking feature is the splitting of the phase transition at T_1 into a second-order transition at T_{+1}=6.9 +/- 0.05K and a first-order transition at T_{-1}=6.7 +/- 0.05K. For the four phase transitions, the quadrupolar order parameters and the respective symmetry changes are specified.Comment: 14 pages (RevTex), 3 eps-figures, accepted by PR

Scientific complications and controversies noted in the field of CdS/CdTe thin film solar cells and the way forward for further development

Cadmium telluride-based solar cell is the most successfully commercialised thin film solar cell today. The laboratory-scale small devices have achieved ~ 22%, and commercial solar panels have reached ~ 18% conversion efficiencies. However, there are various technical complications and some notable scientific contradictions that appear in the scientific literature published since the early 1970s. This review paper discusses some of these major complications and controversies in order to focus future research on issues of material growth and characterisation, post-growth processing, device architectures and interpretation of the results. Although CdTe can be grown using more than 14 different growth techniques, successful commercialisation has been taken place using close-space sublimation and electrodeposition techniques only. The experimental results presented in this review are mainly based on electrodeposition. Historical trends of research and commercial successes have also been discussed compared to the timeline of novel breakthroughs in this field. Deeper understanding of these issues may lead to further increase in conversion efficiencies of this solar cell. Some novel ideas for further development of thin film solar cells are also discussed towards the end of this paper

The Future of Rheumatoid Arthritis and Hand Surgery - Combining Evolutionary Pharmacology and Surgical Technique

Rheumatoid arthritis is a systemic autoimmune disease of uncertain aetiology, which is characterized primarily by synovial inflammation with secondary skeletal destructions

Design for Mobile Mental Health:An Exploratory Review

A large number of mobile mental health apps are available to the public but current knowledge about requirements of designing such solutions is scarce, especially from sociotechnical and user centred points of view. Due to the significant role of mobile apps in the mental health service models, identifying the design requirements of mobile mental health solutions is crucial. Some of those requirements have been addressed individually in the literature, but there are few research studies that show a comprehensive picture of this domain. This exploratory review aims to facilitate such holistic understanding. The main search keywords of the review were identified in a cross-disciplinary requirements workshop. The search was started by finding some core references in the healthcare databases. A wider range of references then has been explored using a snowball method. Findings showed that there is a good understanding of individual design requirements in current literature but there are few examples of implementing a combination of different design requirements in real world products. The design processes specifically developed for mobile mental health apps are also rare. Most studies on operational mobile mental health apps address major mental health issues while prevention and wellbeing areas are underdeveloped. In conclusion, the main recommendations for designing future mobile mental health solutions include: moving towards sociotechnical and open design strategies, understanding and creating shared value, recognizing all dimensions of efficacy, bridging design and medical research and development, and considering an ecosystem perspective

Review of CdTe1−xSex Thin Films in Solar Cell Applications

Recent improvements in CdTe thin film solar cells have been achieved by using CdTe1−xSex as a part of the absorber layer. This review summarizes the published literature concerning the material properties of CdTe1−xSex and its application in current thin film CdTe photovoltaics. One of the important properties of CdTe1−xSex is its band gap bowing, which facilitates a lowering of the CdTe band gap towards the optimum band gap for highest theoretical efficiency. In practice, a CdTe1−xSex gradient is introduced to the front of CdTe, which induces a band gap gradient and allows for the fabrication of solar cells with enhanced short-circuit current while maintaining a high open-circuit voltage. In some device structures, the addition of CdTe1−xSex also allows for a reduction in CdS thickness or its complete elimination, reducing parasitic absorption of low wavelength photons

Elastic microanalysis at lower temperatures

Elastic microanalysis at lower temperatures / V. Müller ... - In: International Conference on Internal Friction and Ultrasonic Attenuation in Solids : ICIFUAS 11 / ed. by: A. Rivière ... - Les Ulis : Ed. de Physique, 1996 (1997). - S. 787-790. - (Journal de physique : 4, Colloque ; 1996,8

Elastic Microanalysis at Lower Temperatures

Acoustic microscopy is wellknown nowadays as a powerful non-destructive tool to investigate the local elastic and structural properties of compact materials, composites and films. However, the application of commercial microscopes is limited to temperatures near ambient, because aqua dest. as a quite suitable immersion fluid is usually prefered. Here we report on our recent investigations, which are governed by the aim to extend elastic microanalysis to temperatures well below room temperature. All measurements are done between 90K and 230K by use of liquid propane as acoustic bonding medium. It is shown that elastic microanalysis at 1GHz can be successfully performed but is considerably affected by the strong temperature dependent properties of the coupling fluid chosen

Ultrasonic Study of the Elastic Behaviour of Zone Refined Single Crystalline Rhodium

We report on temperature dependent sound velocity measurements performed below ambient temperature on a rhodium single-crystal of exceptional high purity of about 99.999%. In particular, the excellent acoustic quality of the sample permits a quite accurate determination of the elastic moduli for a sound frequency covering the range between 20 and 150 MHz. Primarily our investigations concentrate on the role of the electrons in single-crysalline rhodium which band structure, as speculated, causes a considerable elastic anisotropy and therefore gives rise also to the peculiar mechanical properties commonly known from the poly-crystalline material. A comparative analysis of al1 stiffness coefficients based on our sound data reveals a strong shear rigidity indicating quite angular dependent crystal forces, which are indeed not reminiscent of ordinary metals. Also the temperature dependence studied in detail equally points out that the electronic band structure of rhodium has to be taken into account for a satisfactory description of the elastic behaviour and cannot be treated properly within the free electron model