BashDungeon

We present here the first of a series of video-games designed for teaching fundamentals of computer science to university students. We built the game as an adventure inside a dungeon, which aims at reproducing the topology of a Unix file system. Inside the different rooms, the players can learn how to use several Unix commands, from simple file system actions to complex text manipulations, to complete the quests and win the game. We performed a user test on a class of B.Sc. students at the University of Cagliari. The results show a good acceptance of the game metaphor and its effectiveness in supporting the learning process. We plan to expand this game and to design similar games for teaching object-oriented programming and algorithms and data structures.

     

Off-line coupling of capillary electrophoresis to substrate-assisted laser desorption inductively coupled plasma mass spectrometry

A novel off-line coupling of capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICPMS) is reported here. The coupling interface is based on the connection of a separation capillary to a deposition capillary via a liquid junction maintaining high separation efficiency and sample utilization due to the self-focusing effect and lack of pressure-induced flow in comparison with nebulizer-like interfaces. The separation is recorded in the form of droplets of CE effluent on a suitable substrate--a poly(ethylene terephthalate) glycol (PETG) sample plate placed inside a partially evacuated chamber. Substrate-assisted laser desorption (SALD) is used to vaporize the sample fractions and to enable further transfer to the ICPMS. The mechanism of SALD is examined using model samples deposited on a variety of substrates. The highest response is obtained for a PETG substrate; sample desorption due to ablation of PETG is found to outweigh direct ablation of sample. Detection limits are given for several metal elements. Finally, a rapid (2.5-min), high-resolution separation of Cr(III)/Cr(VI) species injected in subpicomolar quantity is shown.     

Effect of whey concentration on protein recovery in fresh ovine ricotta cheese

Ricotta cheese, particularly the ovine type, is a typical Italian dairy product obtained by heat-coagulation of the proteins in whey. The aim of this work was to investigate the influence of whey protein concentration, obtained by ultrafiltration, on yield of fresh ovine ricotta cheese. Ricotta cheeses were obtained by thermocoagulation of mixtures with protein content of 1.56, 3.10, 4.16, and 7.09 g/100 g from the mixing of skim whey and ultrafiltered skim whey. A fat-to-protein ratio of 1.1 (wt/wt) was obtained for all mixtures by adding fresh cream. The initial mixtures, as well as the final ricotta cheeses, were analyzed for their composition and by SDS-PAGE. Protein bands were quantified by QuantityOne software (Bio-Rad, Hercules, CA) and identified by liquid chromatography-tandem mass spectrometry. Significant differences in the composition of the ricotta cheese were observed depending on protein concentration. Particularly, ricotta cheese resulting from the mixture containing 7.09 g/100 g of protein presented higher moisture (72.88 ± 1.50 g/100 g) and protein (10.18 ± 0.45 g/100 g) contents than that prepared from the mixture with 1.56 g/100 g of protein (69.52 ± 1.75 and 6.70 ± 0.85 g/100 g, respectively), and fat content was lower in this sample (12.20 ± 1.60 g/100 g) compared with the other treatments, with mean values between 15.72 and 20.50 g/100 g. Each protein fraction presented a different behavior during thermocoagulation. In particular, the recovery of β-lactoglobulin and α-lactalbumin in the cheese increased as their content increased in the mixtures. It was concluded that concentrating ovine rennet whey improved the extent of heat-induced protein aggregation during the thermal coagulation process. This resulted in a better recovery of each protein fraction in the product, and in a consequent increase of ricotta cheese yield.     

Biological and biochemical properties of the carbon composite and polyethylene implant materials

We studied the biocompatibility of the carbon composites and polyethylene materials with and without collagen or collagen and proteoglycan cover. We used the in vitro technology to study the adhesion of model cells evalution, their metabolic activity and the production of TNF- as a cytokine model. Under in vivo condition, the biocompatibility of tested polymers were studied in the implantation experiment, subcutaneously in the interscapular region in the laboratory rat. We have found in the in vitro assay favorable proliferation and the smallest production of pro-inflammatory TNF- cytokine in cells adherent to the hydrophobic polyethylene material coated with biological macromolecules. Using in vivo tests performed by the implantation of materials to the rat we demonstrated that the materials are not cytotoxic. The tissue capsule surrounding the implants was not significantly influenced by the type of the implant and the pre-treatment by the biological molecules. However, the foreign-body giant multinucleated cells were observed only in the vicinity of the collagen – covered hydrophobic polyethylene implant. Interestingly, while the collagen coating improved the biocompatibility of tested polymers in vitro, the inflammatory reaction against this covered materials was higher under in vivo conditions. The pre-treatment of carbon composites by both types of biological macromolecules reduced the occurrence of carbon debris in the implantation site. The tested carbon composites and polyethylene materials are not toxic. The pre-treatment of the materials by extracelular matrix components increased their biological tolerance in vitro and reduced implant wears in animal experiment, which can be important for the medical application.     

Effect of the tripeptide glycyl-L-histidyl-L-lysine on the proliferation and synthetic activity of chick embryo chondrocytes

Under certain conditions chondrocytes form lattices with cartilage collagens, which may serve as cartilage implants. It is necessary to find the optimal conditions for culturing chondrocytes. Three different supports are compared: (a) plastic; (b) cartilage collagens; and (c) insoluble skin collagen solubilized under denaturing conditions (ISC-40). The effect of culture medium supplementation with the tripeptide (Gly-His-Lys)2.Cu.2H2O.2NaCl (GHK) on chondrocyte proliferation and synthetic activity is studied, with particular attention paid to collagen types I, II and III. The collagen supports stimulated chondrocyte proliferation, but on the ISC-40 support they started to dedifferentiate rather early. In the primary culture, chondrocytes on all three supports synthesized mainly collagen type II, and only small amounts of types I and III. In the first passage the synthesis of these two collagen types increased, relative to collagen type II, at least on the cartilage collagen support. Supplementation of culture medium with GHK stimulated chondrocyte proliferation in the primary structure mostly on the ISC-40 support. On the other two types of supports the stimulatory effect of GHK was expressed mostly in the first passages. The collagen synthetic rate was increased by GHK on both of the collagen supports; on the cartilage collagen support collagen type II was synthesized predominantly and on the ISC-40 support types I and III were mostly formed. It is suggested that supplementation of culture medium with GHK may be useful in the preparation of cartilage implants.     

Biomechanical and biological properties of the implant material carbon-carbon composite covered with pyrolytic carbon

The aim of this study was to test C/C material (carbonized, graphitized or covered with pyrolytic carbon) designated for the use in orthopaedic and bone surgery. Using an in vitro assay we confirmed, that the cell proliferation was exhibited the mostly on the C/C composite coated with pyrolitic carbon and afterwards polished. The two latest of subsequent water extracts of this material had a slightly inhibiting effect on the cells metabolic activity. Biocompatibility test in vivo performed subcutaneously on rats did not show big differences between three tested implants (C/C composite, epoxy resine, titanium alloy), on the other hand the plates tested on pigs demonstrated foreign-body reaction induced by wear C/C composite material. Such debris were found both in the neighborhood of the implant as well as in the lymphatic node.     

Forging compaction of amorphous Co67B33 powders obtained by mechanical alloying

An amorphous mechanically alloyed Co₆₇B₃₃ powder has been compacted by hot forging at 200, 300, 400, 500, 700°C applying a load up to 2 GPa in 2 seconds. The density approaches the theoretical value operating under inert gas at 700°C. The alloy structure changes from amorphous to crystalline. Hardness and wear resistance of the material forged at 700°C are superior to those of the starting amorphous alloy as well as to those of an alloy of identical composition obtained by conventional slow cooling of the melt.     

The combined effect of gaze direction and facial expression on cueing spatial attention.

Empirical evidence shows an effect of gaze direction on cueing spatial attention, regardless of the emotional expression shown by a face, whereas a combined effect of gaze direction and facial expression has been observed on individuals' evaluative judgments. In 2 experiments, the authors investigated whether gaze direction and facial expression affect spatial attention depending upon the presence of an evaluative goal. Disgusted, fearful, happy, or neutral faces gazing left or right were followed by positive or negative target words presented either at the spatial location looked at by the face or at the opposite spatial location. Participants responded to target words based on affective valence (i.e., positive/negative) in Experiment 1 and on letter case (lowercase/uppercase) in Experiment 2. Results showed that participants responded much faster to targets presented at the spatial location looked at by disgusted or fearful faces but only in Experiment 1, when an evaluative task was used. The present findings clearly show that negative facial expressions enhance the attentional shifts due to eye-gaze direction, provided that there was an explicit evaluative goal present. (PsycINFO Database Record (c) 2010 APA, all rights reserved)