Changes in circulating biomarkers during a single hemodialysis session

The hemodialysis (HD) procedure induces an inflammatory response potentially contributing to cardiovascular disease. Here we investigated the acute impact of HD on circulating biomarkers. Circulating biomarkers (small solutes, middle molecular‐sized peptides, and proteins) related to inflammation, oxidative stress, and vascular calcification (VC) were measured before and after a single session of HD in 45 clinically stable patients. Concentrations were corrected for ultrafiltration‐induced hemoconcentration. Among vascular calcification‐related biomarkers, osteoprotegerin and fetuin‐A remained unchanged while fibroblast growth factor‐23 (FGF23) decreased by ?19%. Changes of FGF23 and changes of phosphate correlated (ρ = 0.61, P < 0.001). While C‐reactive protein did not change, interleukin‐6 (IL‐6) increased by 14% and pentraxin 3 (PTX3) increased by 45%. IL‐6 and PTX3 appear to be valid biomarkers of the intradialytic inflammatory response. VC‐related markers were in general not affected by the single HD session; however, the observed correlation between acute changes of FGF‐23 and phosphate during HD warrants further studies.     

Fracture toughness and growth of short and long fatigue cracks in ductile cast iron EN‐GJS‐400‐18‐LT

Heavy components of ductile cast iron frequently exhibit metallurgical defects that behave like cracks under cyclic loading. Thus, in order to decide whether a given defect is permissible, it is important to establish the fatigue crack growth properties of the material. In this paper, results from a comprehensive study of ductile cast iron EN‐GJS‐400‐18‐LT have been reported. Growth rates of fatigue cracks ranging from a few tenths of a millimetre (‘short’ cracks) to several millimetres (‘long’ cracks) have been measured for load ratios R=?1, R= 0 and R= 0.5 using a highly sensitive potential‐drop technique. Short cracks were observed to grow faster than long cracks. The threshold stress intensity range, ΔK_th, as a function of the load ratio was fitted to a simple crack closure model. Fatigue crack growth data were compared with data from other laboratories. Single plain fatigue tests at R=?1 and R= 0 were also carried out. Fracture toughness was measured at temperatures ranging from ?40 °C to room temperature.     

Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel

High speed steel hacksaw blade blanks were laser surface melted and rapidly solidified along one edge. The laser melting resulted in complete carbide dissolution. By subsequent machining and heat treatments saw teeth were manufactured with a refined internal structure of the edges and corners. The structure was fully martensitic with a uniform and dense dispersion of small primary carbides. Sawing tests in quenched and tempered steel showed that blade life was somewhat improved, as compared to conventionally heat treated blades. The increased wear resistance is believed to be due to improved toughness along with high hardness caused by the refined carbide structure. Sawing tests in austenitic stainless steel did not give any significant improvement in performance. The effect of the altered microstructure on performance is likely to be more or less pronounced depending on application, tool and work material.     

The effect of macroscopic solute diffusion in the liquid upon surface macrosegregation

An existing one-dimensional mathematical model that predicts the macrosegregation formation due to solidification shrinkage has been modified to also account for the macroscopic diffusion of solute in the liquid. It is shown both numerically and analytically that such solute diffusion has an almost negligible influence on the predicted solute profile, except in a very thin layer near the chill surface, where severe solute depletion develops. This layer is related to a discontinuity in the diffusive solute flux at the surface, and for a moderately cooled Al-4.5 pct Cu alloy, the layer thickness is of the order 100 μm. When the lever rule is imposed, the solute concentration at the surface becomes equal to the partition coefficient multiplied by the nominal alloy concentration, and the boundary layer solidifies completely once the temperature drops below the liquidus temperature of the (initial) melt. This indicates that assuming local thermodynamical equilibrium at a domain boundary when simultaneously accounting for the macroscale solute diffusion should be reconsidered in macrosegregation modeling.     

MIMO PID tuning via iterated LMI restriction

We formulate multi‐input multi‐output proportional integral derivative controller design as an optimization problem that involves nonconvex quadratic matrix inequalities. We propose a simple method that replaces the nonconvex matrix inequalities with a linear matrix inequality restriction, and iterates to convergence. This method can be interpreted as a matrix extension of the convex–concave procedure, or as a particular majorization–minimization method. Convergence to a local minimum can be guaranteed. While we do not know that the resulting controller is globally optimal, the method works well in practice, and provides a simple automated method for tuning multi‐input multi‐output proportional integral derivative controllers. The method is readily extended in many ways, for example, to the design of more complex, structured controllers. Copyright © 2015 John Wiley & Sons, Ltd.     

Determination of the vapor pressures of moth sex pheromone components by a gas chromatographic method

The vapor pressures of decyl acetate, five decenyl acetate isomers, (Z)-7-dodecenyl acetate, and (Z)-9-tetradecenyl acetate have been determined at three to six temperatures in the interval 25–45 °C by a gas Chromatographic method suitable for accurate measurements of the low vapor pressures of moth sex pheromone components at biologically relevant temperatures. The vapor pressure values at 30.5 °C are 3.80 Pa for decyl acetate, 4.08–5.40 Pa for the decenyl acetate isomers, 0.562 Pa for (Z)-7-dodecenyl acetate, and 0.094 Pa for (Z)-9-tetradecenyl acetate. The vapor pressures of the decenyl acetates show a small but significant dependence on the double bond position. Four of the compounds in this study, 10Ac,Z5–10Ac,Z7–12Ac, andZ9–14Ac have recently been identified as sex pheromone components of the turnip moth,Agrotis segetum. Large differences between the mole percentages of the component as found in liquid extracts of female abdominal tips and the corresponding mole percentages in the vapor phase are predicted.     

Preparation of fetal rat brains for light and electron microscopy

To study cellular shapes, growth patterns, and fine structure during early stages of CNS development in rat embryos, preparative procedures were evaluated and modified to meet two criteria: (1) Coronal semithin sections should reveal undeformed telencephalic hemispheres that were symmetrically expanded on both sides of midline structures and were surrounded by contiguous mesenchyme. (2) In electron micrographs, cells should have intact, undistorted surface membranes, evenly distributed nucleoplasm and well preserved cytoplasmic organelles. To meet these criteria, 378 fetuses with a gestational age of 11–20 days (E11–E20) were used to test and modify procedures for anesthesia, embryo removal and handling, dissection, fixation, dehydration, and embedding of the embryonic CNS. Most specimens were in an early stage of development (E11–E13), which, in case of the neopallial wall, is the preneural period. The tests produced methods that met the above criteria and identified the most common artifacts and their causes. Deformities of the cerebral hemispheres and separations between the brain and its coverings were usually caused by trauma during embryo removal and during handling before fixation. Changes in cellular volumes, especially swelling during fixation and dehydration, were the most important causes of histological artifacts. The procedures and methods that consistently produced the best light and electron microscopic preservation of the E11–E13 rat CNS are described. Fixation was best when the brains were treated with glutaraldehyde and s-collidine buffer, followed by osmium tetroxide in s-collidine buffer. A surprisingly beneficial effect of sodium chloride in the dehydrating alcohol was noted.