Photoluminescence of CuInS2 single crystals grown by traveling heater and chemical vapor transport methods

Photoluminescence of CuInS2 single crystals grown by both the traveling heater method (THM) and chemical vapor transport (CVT) has been investigated at 4.2, 78, and 300 K. Intense emission in the near-band-edge region caused by free and bound excitons has been detected for both types of crystals. Taking into account the energy position of the luminescence line of the ground (n = 1) and first excited (n = 2) states, the binding energy for free A excitons has been estimated to be about 19.7 and 18.5 meV for CuInS2 grown by CVT and THM, respectively

A Context Aware Notification Architecture Based on Distributed Focused Crawling in the Big Data Era

The amount of data created in various sources over the Web is tremendously increasing. Trying to keep track of relevant sources is an increasingly time-consuming task. The traditional way of accessing information over the Web is pull-based. Users need to query data sources in certain time intervals where an important piece of information can be lately recognized or even missed completely. Technologies including RSS help users to get push-based notifications from websites. Discovering the relevant information without a notification overload is still not possible with existing technologies. Despite some promising efforts in push-based architectures to solve this problem, they fall short to meet the requirements in the big data era. In this study, by leveraging the latest advancements in distributed computing and big data analytics technologies, we use a focused crawling approach to propose a context aware notification architecture for people to find desired information at its most valuable state

Effects of D+ implantation of CIGS thin films through a CdS layer

Cu(InGa)Se2 thin films coated with a 30 nm CdS layer were implanted with doses of 1014–1016 cm−2 of 2.5 keV D+ at room temperature. Implanted and non-implanted areas of the films were characterised using low-temperature photoluminescence (PL). A broad band (A) at 1.07 eV, attributed to the band-tail recombination, dominated the PL spectra from the non-implanted material. Implantation of D+ generated four new transitions in the PL spectra: 3 low-energy peaks; and a dominant peak at 1.10 eV. The blue shift of the 1.10 eV band with excitation power rise was shown to be only half that of band A. This was attributed to the passivating effects of D+ on the amplitude of the band-tail potential fluctuations

Contact angle hysteresis in the clay-water-air system of soils

The purpose of this research is to study the change in wettability of clays due to the influence of mesophilic soil microorganisms' activity when adding model contaminants: water-in-oil emulsion, glycerol and oleic acid. During the experiments, the objectives of this study were to specify peculiarities of wetting contact angle hysteresis of clays with substrates of different mineral composition and microbial activity. Hydrophilicity/hydrophobicity of the stimulator for microbial activity does not have a clear effect on clay properties. The surface heterogeneity mostly increases with time, perhaps, due to biofilm exudates whatever was a type of microbial stimulator. Chemical and geometric heterogeneities played comparable roles in the surface hydrophilic-hydrophobic balance. Results obtained prove that microbial communities and/or the Fe chemical state alteration (pyrite, hematite or goethite) were responsible for both hydrophilization and hydrophobization of the surface. The equation for the drop spreading rate was presented and verified by well comparison of experimental results with simulations.179-19