A feasibility study of using CeO2 as a surrogate material during the investigation of UO2 thermal conductivity enhancement

A possible substitution of UO₂ for research purposes is the cerium dioxide (CeO₂) owing to its chemical and physical properties. Neutronic properties are different and fission is absent in the case of CeO₂; however, similarities were studied recently to have a possibility to compare the neutronic influence of secondary additives into the matrix. This paper deals with increasing the thermal conductivity of UO₂ nuclear fuel on surrogate material (CeO₂); the main focus of the research is given on the sintering behaviour of CeO₂. The incorporation of highly thermally conductive material (SiC) is the investigated concept of thermal conductivity enhancement. Conventional sintering and spark plasma sintering (SPS) were applied to compare the behaviour of CeO₂ and UO₂ reported in the literature. High temperature thermal conductivity measurements did not confirm the positive influence of SiC additive inside the CeO₂ matrix mainly due to grain boundary disruptions. Similar behaviour was also previously reported for UO₂ pellets with SiC.     

Polymer chain mobility in polyelectrolyte multilayers

Free-standing polyelectrolyte multilayer membranes have been formed by the layer-by-layer technique using a dip-coating apparatus. The polymer-chain mobility has been studied by ¹H relaxation in the rotating frame T _1rho NMR with ¹³C chemical shift resolution. For each of the individual polymers a single relaxation component has been observed for all resolved signals. In the multilayer a significantly different relaxation time T _1rho has been observed with a minor second component. The interaction between the oppositely charged polyelectrolytes influences the molecular mobility.     

Cultivation of human keratinocytes without feeder cells on polymer carriers containing ethoxyethyl methacrylate: in vitro study

The cell/tissue engineering therapy of extensive or chronic skin wounds is a highly topical task of the contemporary medicine. One of possible therapeutic approaches is grafting of in vitro cultured keratinocytes directly to the wound bed, where the cells colonize the wound, proliferate and improve the re-epithelization process. Because the successful cultivation of keratinocytes needs an application of feeder cells, the exclusion of these cells from the cultivation system is highly required. In this study we show a positive influence of 2-ethoxyethyl methacrylate as a component of cultivation support on growth of keratinocytes without feeder cells. Keratinocytes cultured on these surfaces are able to migrate to the model wound bed in vitro, where they form distinct colonies and have a normal differentiation potential.     

Characterization of a near-infrared laparoscopic hyperspectral imaging system for minimally invasive surgery

We developed and characterized a new imaging platform for minimally invasive surgical venues, specifically a system to help guide laparoscopic surgeons to visualize biliary anatomy. This platform is a novel combination of a near-infrared hyperspectral imaging system coupled with a conventional surgical laparoscope. Intraoperative tissues are illuminated by optical fibers arranged in a ring around a center-mounted relay lens collecting back-reflected light from tissues to the hyperspectral imaging system. The system consists of a focal plane array (FPA) and a liquid crystal tunable filter, which is continuously tunable in the near-infrared spectral range of 650-1100 nm with the capability of passing light with a mean bandwidth of 6.95 nm, and the FPA is a high-sensitivity back-illuminated, deep depleted charge-coupled device. Placing a standard resolution target 5.1 cm from the distal end of the laparoscope, a typical intraoperative working distance, produced a 7.6-cm-diameter field of view with an optimal spatial resolution of 0.24 mm. In addition, the system's spatial and spectral resolution and its wavelength tuning accuracy are characterized. The spectroscopic images are formatted into a three-dimensional hyperspectral image cube and processed using principle component analysis. The processed images provide contrast based on measured spectra associated with chemically different anatomical structures helping identify the main molecular chromophores inherent to each tissue. The principal component images were found to image swine gallbladder and biliary structures from surrounding tissues, in real time, during cholecystectomy surgery. Furthermore, it is shown that surgeons can interrogate selected image subregions for their molecular composition identifying biliary anatomy during surgery and before any invasive action is undertaken.     

Acceptable Programs Revisited

Acceptable logic programs have been studied extensively in the context of proving termination of Prolog programs. It is difficult, however, to establish acceptability from the definition since this depends on finding a suitable model, which need not be a Herbrand model in general, together with a suitable level mapping that one can use to check the conditions which characterize acceptability. In this paper, we will see that when working over a fixed but arbitrary preinterpretation, a method can be provided for obtaining both a suitable model and a canonical level mapping which are sufficient for this purpose. Furthermore, the canonical model and level mapping obtained will turn out to be sufficient for discussing termination of non-ground queries.     

Postdoctoral training in professional geropsychology: A survey of fellowship graduates.

Have psychologists who have pursued postdoctoral training in geropsychology viewed such training as a worthwhile professional investment? As the population is aging, psychologists are increasingly working with older adults. For many psychologists, competent practice with the elderly will require some continuing education, whereas other psychologists may choose to secure specialty-level training in the field. A survey of psychologists who completed such specialized postdoctoral training found a high level of satisfaction with the training and a sense of professional competence in most of the geropsychology competency areas set forth by the American Psychological Association. The need for increased opportunities for both proficiency and specialty-level training in applied geropsychology is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biodiesel from rapeseed oil,methanol and KOH. 3. Analysis of composition of actual reaction mixture

Detailed analysis is described of the samples taken after suitable reaction times from the actual reaction mixture during the production of biodiesel fuel using methanolysis of rapeseed oil catalyzed by KOH. Three methods for stoppage of reaction (neutralisation of catalyst, dilution by two suitable solvents) in the sample are used. The contents of mono‐, di‐ and triacylglycerols, methylesters of fatty acids (biodiesel) and potassium salts of fatty acids of rapeseed oil, glycerol (by HPLC method), basicity (by potentiometric titration) and water (by GC and Karl‐Fischer method) in the samples are determined. An example of these determinations is described.     

Challenges and Costs of Asexuality: Variation in Premeiotic Genome Duplication in Gynogenetic Hybrids from Cobitis taenia Complex

The transition from sexual reproduction to asexuality is often triggered by hybridization. The gametogenesis of many hybrid asexuals involves premeiotic genome endoreplication leading to bypass hybrid sterility and forming clonal gametes. However, it is still not clear when endoreplication occurs, how many gonial cells it affects and whether its rate differs among clonal lineages. Here, we investigated meiotic and premeiotic cells of diploid and triploid hybrids of spined loaches (Cypriniformes: Cobitis) that reproduce by gynogenesis. We found that in naturally and experimentally produced F1 hybrids asexuality is achieved by genome endoreplication, which occurs in gonocytes just before entering meiosis or, rarely, one or a few divisions before meiosis. However, genome endoreplication was observed only in a minor fraction of the hybrid’s gonocytes, while the vast majority of gonocytes were unable to duplicate their genomes and consequently could not proceed beyond pachytene due to defects in bivalent formation. We also noted that the rate of endoreplication was significantly higher among gonocytes of hybrids from natural clones than of experimentally produced F1 hybrids. Thus, asexuality and hybrid sterility are intimately related phenomena and the transition from sexual reproduction to asexuality must overcome significant problems with genome incompatibilities with a possible impact on reproductive potential.     

A Complex Evaluation of the In-Vivo Biocompatibility and Degradation of an Extruded ZnMgSr Absorbable Alloy Implanted into Rabbit Bones for 360 Days

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure—the removal of the plates and screws—can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.     

IL-6 in the Ecosystem of Head and Neck Cancer: Possible Therapeutic Perspectives

Interleukin-6 (IL-6) is a highly potent cytokine involved in multiple biological processes. It was previously reported to play a distinct role in inflammation, autoimmune and psychiatric disorders, ageing and various types of cancer. Furthermore, it is understood that IL-6 and its signaling pathways are substantial players in orchestrating the cancer microenvironment. Thus, they appear to be potential targets in anti-tumor therapy. The aim of this article is to elucidate the role of IL-6 in the tumor ecosystem and to review the possible therapeutic approaches in head and neck cancer.