Hard amorphous silicon carbonitride coatings produced by plasma enhanced chemical vapour deposition

Hard amorphous silicon carbonitride coatings for wear resistance have been produced by d.c. plasma‐enhanced chemical vapour deposition on pure iron at 573 K. Compared with most plasma assisted processes work was conducted under a relatively high pressure of 130 Pa. The advantages of this technique are an amorphous film structure, high deposition rates (up to 2 μm/min), high hardness and simple equipment. Hexamethyldisilazan (HMDSN) was used as precursor and argon, hydrogen, nitrogen and ammonia as process gases. The dependence of the coatings on the process parameters (process gas and d.c. power) was investigated. The characterization of the samples was carried out mainly by Fourier transform infrared spectrometry (FTIR), electron probe microanalysis (EPMA) and hardness measurement. Samples show clearly the infrared spectra absorption bands characteristic of SiC and Si₃N₄, with traces of hydrogen bonding. The material structure shows a strong dependence on the process gas and the d.c. power. However, for argon and hydrogen were deposited carbon‐rich SiC films with low nitrogen content. Nitridic films with low carbon content were deposited using nitrogen and especially ammonia. The hardness of the produced coatings was about 10 ‐ 55 GPa.     

How accurately does Thomas Kuhn’s model of paradigm change describe the transition from the static view of the universe to the big bang theory in cosmology?

Up to the 1960s the prevalent view of science was that it was a step-by-step undertaking in slow, piecemeal progression towards truth. Thomas Kuhn argued against this view and claimed that science always follows this pattern: after a phase of “normal” science, a scientific “revolution” occurs. Taking as a case study the transition from the static view of the universe to the Big Bang theory in cosmology, we appraised Kuhn’s theoretical approach by conducting a historical reconstruction and a citation analysis. As the results show, the transition in cosmology can be linked to many different persons, publications, and points in time. The findings indicate that there was not one (short term) scientific revolution in cosmology but instead a paradigm shift that progressed as a slow, piecemeal process.     

Ginger—Mechanism of action in chemotherapy-induced nausea and vomiting: A review

Despite advances in antiemetic therapy, chemotherapy-induced nausea and vomiting (CINV) still poses a significant burden to patients undergoing chemotherapy. Nausea, in particular, is still highly prevalent in this population. Ginger has been traditionally used as a folk remedy for gastrointestinal complaints and has been suggested as a viable adjuvant treatment for nausea and vomiting in the cancer context. Substantial research has revealed ginger to possess properties that could exert multiple beneficial effects on chemotherapy patients who experience nausea and vomiting. Bioactive compounds within the rhizome of ginger, particularly the gingerol and shogaol class of compounds, interact with several pathways that are directly implicated in CINV in addition to pathways that could play secondary roles by exacerbating symptoms. These properties include 5-HT₃, substance P, and acetylcholine receptor antagonism; antiinflammatory properties; and modulation of cellular redox signaling, vasopressin release, gastrointestinal motility, and gastric emptying rate. This review outlines these proposed mechanisms by discussing the results of clinical, in vitro, and animal studies both within the chemotherapy context and in other relevant fields. The evidence presented in this review indicates that ginger possesses multiple properties that could be beneficial in reducing CINV.     

The Semijoin Algebra and the Guarded Fragment

In the 1970s Codd introduced the relational algebra, with operators selection, projection, union, difference and product, and showed that it is equivalent to first-order logic. In this paper, we show that if we replace in Codd’s relational algebra the product operator by the “semijoin” operator, then the resulting “semijoin algebra” is equivalent to the guarded fragment of first-order logic. We also define a fixed point extension of the semijoin algebra that corresponds to μGF.This author has been partially supported by the European Community Research Training Network “Games and Automata for Synthesis and Validation” (GAMES), contract HPRN-CT-2002-00283.     

List edge multicoloring in graphs with few cycles

The list edge multicoloring problem is a version of edge coloring where every edge e has a list of available colors L(e) and an integer demand x(e). For each e, we have to select x(e) colors from L(e) such that adjacent edges receive disjoint sets of colors. Marcotte and Seymour proved a characterization theorem for list edge multicoloring trees, which can be turned into a polynomial time algorithm. We present a slightly more general algorithm that works also on odd cycles. A variant of the method leads to a randomized polynomial time algorithm for handling even cycles as well.