Strength recovery in fractured sheep tibia treated with a plate or an internal fixator: an experimental study with a two-year follow-up

Lung adenocarcinoma is the most common cell type in females (smokers or non-smokers) and in non-smoking males. Its incidence has been increasing in younger cohorts of males and females until very recent years. Changes in classification and in pathological techniques account for some of this increase. In females and non-smoker males, the increase could be partly due to a detection bias in former studies. Nevertheless, successive cohorts over time seem more likely to develop adenocarcinoma and less likely to develop squamous cell carcinoma. These differences between birth cohorts suggest that the increasing incidence of adenocarcinoma is not only due to changes in pathological diagnosis. Geographical differences are also observed: in Europe, the squamous cell type still predominates and an increase in incidence of adenocarcinoma has only been reported in the Netherlands. In Asia, in the 1960s and 1970s, the proportion of adenocarcinoma was higher than in North America or Europe and seems to be increasing. To what extent these differences are due to differences. In establishing diagnosis remains unknown. Despite these biases in temporal and geographical trends detailed in this review, there has probably been a true increase in incidence of adenocarcinoma. An explanation for this should be sought in studies on detailed smoking history and passive smoking exposure, occupational exposure, diet and cooking, pollution and other environmental factors.     

Inhibition of anaesthetic-induced emesis by a NK1 or 5-HT3 receptor antagonist in the house musk shrew, Suncus murinus

The effects of a NK1 antagonist, GR205171, and a 5-HT3 antagonist, ondansetron, in a novel model of post-anaesthesia-induced emesis in Suncus murinus is described. GR205171 (1 and 3 mg k(-1) s.c) and ondansetron (3 mg kg(-1) s.c.) each significantly inhibited emesis. This model may be useful for studying drugs to treat post-operative nausea and vomiting in man.     

Electrodeposited Zn–TiO<Subscript>2</Subscript> nanocomposite coatings and their corrosion behavior

The present paper aims to investigate the electrodeposition on steel substrate and the corrosion behavior of Zn–TiO₂ nanocomposite coatings. Zn–TiO₂ composite coatings were electrodeposited on OL 37 steel from an electrolyte containing ZnCl₂, KCl, HBO₃ (pH 5.7) brightening agents and dispersed nanosized TiO₂. Corrosion measurements were performed in 0.2 g L⁻¹ (NH₄)₂SO₄ solution (pH 3) by using electrochemical methods (open-circuit potential measurements, polarization curves, electrochemical impedance spectroscopy). The results of electrochemical measurements were corroborated with those obtained by using non-electrochemical methods (X-ray diffraction, atomic force microscopy and scanning electron microscopy). The results indicate that the composite coatings exhibit higher corrosion resistance as compared to pure Zn coatings and a non-linear dependence of their polarization resistance on TiO₂ concentration in the plating bath was found. The importance of TiO₂ nature and concentration regarding the properties of the composite coatings was demonstrated.     

Increased sensibility of mixed ferrite humidity sensors by subsequent heat treatment

The study presents the effects of different calcination temperatures on the size and morphology of mixed Co‐Ni ferrites, and the respective changes in the magnetic and electrical properties, with emphasis on their applicability as humidity sensors. The data suggests that the heat treatment does not significantly change the magnetic properties, but significant variations on the morphology of the nanoparticles, correlated with large changes in the electrical properties of the nanoparticles in terms of electrical permittivity and resistivity with electrical field frequency and humidity, with a clear influence of the calcination temperature over the sensibility of the materials to humidity.     

Liquid crystalline polymers, 9. Synthesis and thermal behavior of some oligomers containing a diethyletheric spacer

Polyethers based on bis(2-chloroethyl) ether and various bisphenols were obtained using a phase transfer catalysis technique in a liquid/liquid system. 4,4′-Dihydroxyazobenzene, 4,4′-dihydroxybiphenyl, bisphenol A, 2,7-dihydroxynaphthalene and 4,4′-dihydroxydiphenyl) sulfide were used. Only the polymers with azobenzene and biphenyl units exhibited mesophases, since the others have semi-crystalline or amorphous structures. The polymers were characterized by ¹H NMR, DSC and optical microscopy in polarized light. The molecular weights of the samples were low, situated in the oligomeric domain. The various transfer rates of the bisphenols from the aqueous to the organic phase, in some cases, led to very different copolymerization ratios as compared to the feed ratios. The LC polymers exhibited monotropic mesophases, probably for conformational reasons. A comparison between similar polyether structures containing the diethyletheric spacer and an oxetanic one was effectuated.     

Comparison of the tissue reaction to implants made of a beta titanium alloy and pure titanium. Experimental study on rabbits

Commercially pure titanium (Ti cp) has been used successfully as an implant material in fracture fixation devices for many years. Ti cp is comparatively soft, but the mechanical properties, such as strength and ductility, can be adjusted by different means over a wide range. Titanium changes its crystal structure from a hexagonal (alpha) phase to the cubic (beta) phase at about 882 °C. Cubic titanium has the advantage of being very malleable (ductile), but in order to stabilize it at room temperature, additions of suitable alloying elements are required. In this study the soft tissue reaction to implants made from a beta titanium alloy (Ti–Mo–Zr–Al) with four different surface treatments is evaluated. The results are compared to Ti cp implants having the same surface conditions, and to electropolished stainless steel plates as controls. A minimum of four small plates of each group were implanted in rabbit tibiae for 3 months. Histomorphometric results show that the thickness of the soft tissue reaction layer, and the number of blood vessels, connective tissue cells (fibroblasts, fibrocytes), lymphocytes, and foreign body giant cells are not significantly different between beta titanium and Ti cp plates. For stainless steel plates the soft tissue reaction layer is thicker, and the numbers of macrophages and connective tissue cells are higher. Excellent biocompatibility was observed for this beta titanium alloy. The mechanical properties of this alloy surpass those of Ti cp, and because of the good tissue tolerance, this material seems to be advantageous and should enter into clinical testing.     

On the modeling and optimal flow control of the Jacksonian network

The modeling and optimal flow control of a Jacksonian network in equilibrium is investigated. The model employed consists of a controller node cascaded with the Jacksonian network. Input packets arrive at the controller node with a Poissonian rate δ. For a blocking type strategy for accessing the network it is shown that the control which maximizes the average throughput of the network subject to a bounded average time delay constraint is a window flow control mechansim. The window size depends on the offered load δ, the maximum service rate of the controlling queueing system, c, and the Norton equivalent service rate of the network μ. The dependence of the average throughput and the average time delay on the control is also analyzed.     

A balanced accumulation scheme for parallel PDE solvers

We present a tailored load balancing technique that addresses specific performance issues in the boundary data accumulation algorithm for non-overlapping domain decompositions. The technique is used to speed up a parallel conjugate gradient algorithm with an algebraic multigrid preconditioner to solve a potential problem on an unstructured tetrahedral finite element mesh. The optimized accumulation algorithm significantly improves the performance of the parallel solver and we show up to 50 % runtime improvements over the standard approach in benchmark runs with up to 48 MPI processes. The load balancing problem itself is a global optimization problem that is solved approximately by local optimization algorithms in parallel that require no communication during the optimization process.