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This article presents the main possibilities for steel refining in Ladle Furnace (LF). These, are presented: steelmaking stages, steel refining through argon bottom stirring, online control of the bottom stirring, bottom stirring diagram during LF treatment of a heat, porous plug influence over the argon stirring, bottom stirring porous plug, analysis of porous plugs disposal on ladle bottom surface, bottom stirring simulation with ANSYS, bottom stirring simulation with Autodesk CFD.

The fidelity of chromosome segregation in mitosis is safeguarded by the precise regulation of kinetochore microtubule (k-MT) attachment stability. Previously, we demonstrated that Cyclin A/Cdk1 destabilizes k-MT attachments to promote faithful chromosome segregation. Here, we use quantitative phosphoproteomics to identify 156 Cyclin A/Cdk1 substrates in prometaphase. One Cyclin A/Cdk1 substrate is myosin phosphatase targeting subunit 1 (MYPT1), and we show that MYPT1 localization to kinetochores depends on Cyclin A/Cdk1 activity and that MYPT1 destabilizes k-MT attachments by negatively regulating Plk1 at kinetochores. Thus, Cyclin A/Cdk1 phosphorylation primes MYPT1 for Plk1 binding. Interestingly, priming of PBIP1 by Plk1 itself (self-priming) increased in MYPT1-depleted cells showing that MYPT1 provides a molecular link between the processes of Cdk1-dependent priming and self-priming of Plk1 substrates. These data demonstrate cross-regulation between Cyclin A/Cdk1-dependent and Plk1-dependent phosphorylation of substrates during mitosis to ensure efficient correction of k-MT attachment errors necessary for high mitotic fidelity.

Mechanisms of ultra-fast laser ablation during deep-drilling of metals was studied using plasma diagnostics and morphological analyses of the laser-induced craters. Fast imaging and time- and space-resolved optical emission spectroscopy were employed to characterize the ablation plume. After irradiation, the crater morphology was analyzed by scanning electron microscopy and optical microscopy. From the correlation between the ablation plume characteristics and the shape of the laser-produced craters, it is shown that the nanoparticles have an important influence on the accuracy of micromachining by ultra-short laser pulses.

Laser material removal is an effective processing technique for hardmetals, which cannot be machined by chip-removal techniques. The basic physics of the laser–matter interactions and the influence of different laser parameters are discussed, with emphasis on sintered WC–Co specific features. The collateral affected zones and their occurrence mechanisms for laser machining with both nanosecond and femtosecond pulses are discussed. Experiments were carried out with pulsed laser systems operating in IR and UV, with ns and fs pulses and their results endorse the theoretical considerations. The use of direct or indirect laser processing (ns and fs pulses) in the surface engineering of coated/uncoated WC–Co parts is also presented. Subsequently, applications like laser microstructuring of tribological WC–Co surfaces and laser machining of integral chipbreakers are discussed.

A computer model to simulate the evolution of parameters describing laser ablation processes was developed. The absorbed laser energy, the heat diffusion, the phase transformations and the shielding effect of the ablated material were taken into account. The temporal development of the ablated volume, pore depth and extension of the melt zone were calculated for single pulses of 500, 100, 20, 5 and 1 ns. Simulations were performed for pulse energies of 50 μJ and spot diameters of 10 μm. From temporal evolution curves of the ablated volumes, the stoppage of the ablation process was evidenced before the end of the processing pulse. Comments with respect to optimal pulse duration (in the ns regime) are also formulated.

The friction and wear reduction in applications that allow only a minimal use of liquid lubricants is done with solid lubricant films or with protective coatings, such as diamond-like carbon (DLC). Further improvements are possible if the geometries of the contact surfaces are modified in a controlled way, as we have already demonstrated it for TiN and TiCN. In this work, the possibilities to generate patterned DLC coated low wear tribological surfaces by means of laser processing were investigated. In the first approach, a two step method was used: steel substrates were laser patterned and subsequently DLC films were deposited on them. The second considered approach was the laser processing of coated surfaces. DLC films were irradiated with laser pulses of different durations and energy densities (100 fs, 800 nm

The response of cemented tungsten carbide and of titanium carbonitride was investigated with respect to damage and ablation properties, under interaction with ultrashort laser pulses. These carbide materials present high microhardness and are of significant interest for tribological applications. The experiments were carried out in air with a commercial Ti:sapphire laser at energy densities on the target up to 6.5 J/cm2. The irradiated target surfaces were analyzed with optical, SEM and AFM techniques and the damage and ablation threshold values were determined using the measured spot diameters and the calculated incident energy density distributions.

Several ultrahard materials and coatings of definite interest for tribological applications were tested with respect to their response when irradiated with fs laser pulses. Results on cemented tungsten carbide and on titanium carbonitride are reported for the first time and compared with outcomes of investigations on diamond and titanium nitride. The experiments were carried out in air, in a regime of 5–8 J/cm2 fluences, using the beam of a commercial Ti:sapphire laser. The changes induced in the surface morphology were analysed with a Nomarski optical microscope, and with SEM and AFM techniques. From the experimental data and from the calculated incident energy density distributions, the damage and ablation threshold values were determined. As expected, the diamond showed the highest threshold, while the cemented tungsten carbide exhibited typical values for metallic surfaces. The ablation rates determined (under the above-mentioned experimental conditions) were in the range 0.1–0.2 μm per pulse for all the materials investigated.

The effect of incorporation of BaCO 3 in portland cement hydration has been studied. From this study it is inferred that presence of BaCO 3 in cements makes them require a higher quantity of mixing water. However, mechanical resistances do not seem negatively affected, for a formation of carboaluminates by chemical reaction between the barium carbonate and the C 3 A of the clinker appears. The BaCO 3 reveals a retardant effect on the setting time, in presence of gypsum as much as in its absence. The BaCO 3 with gypsum reacts as BaSO 4 , a salt of a very high stability. The formation of this barium salt inhibits the formation of ettringite in pastes. Finally, the presence of BaCO 3 in cements ensures that no expansive process will occur in sulphatic means either external or internal, for carbonate is going to react with these sulphates and form BaSO 4 , preventing thus the formation of expansive ettringite.

Background The 5α-reduced pregnane neuroactive steroid (3α,5α)-3-hydroxypregnan-20-one (3α,5α-THP or allopregnanolone) is a potent positive modulator of GABAA receptors capable of modulating neuronal activity. In rats, systemic ethanol (EtOH) administration increases cerebral cortical and hippocampal levels of 3α,5α-THP, but the effects of EtOH on 3α,5α-THP levels in other brain regions are unknown. There is a large body of evidence suggesting that 3α,5α-THP enhances EtOH sensitivity, contributes to some behavioral effects of EtOH, and modulates EtOH reinforcement and motivation to drink. In this study, we used immunohistochemistry (IHC) to determine EtOH-induced changes in cellular 3α,5α-THP expression in brain regions associated with EtOH actions and responses. Methods Male Wistar rats were administered EtOH (2 g/kg) or saline intraperitoneally and after 60 minutes transcardially perfused. IHC was performed on free-floating sections (3 to 4 sections/animal/brain region) using an affinity purified anti-3α,5α-THP primary antibody, and immunoreactivity was visualized with 3,3′-diaminobenzidine. Results EtOH significantly increased 3α,5α-THP immunoreactivity by 24 ± 6% in the medial prefrontal cortex, 32 ± 12% in the hippocampal Cornu Ammonis area 1 (CA1) pyramidal cell layer, 52 ± 5% in the polymorph cell layer of the dentate gyrus (DG), 44 ± 15% in the bed nucleus of the stria terminalis, and 36 ± 6% in the paraventricular nucleus of the hypothalamus. In contrast, EtOH administration significantly reduced 3α,5α-THP immunoreactivity by 25 ± 5% in the nucleus accumbens “shore” and 21 ± 3% in the central nucleus of the amygdala. No changes were observed in the ventral tegmental area, dorsomedial striatum, granule cell layer of the DG, or the lateral and basolateral amygdala. Conclusions The results suggest acute EtOH (2 g/kg) produces divergent, brain region specific, effects on cellular 3α,5α-THP levels. Regional differences in the effects of EtOH suggest there may be regional brain synthesis of 3α,5α-THP independent of the adrenal glands and novel mechanisms that reduce cellular 3α,5α-THP. Regional differences in EtOH-induced changes in 3α,5α-THP levels likely contribute to EtOH effects on neuronal function in brain.

Laser ablation with fs laser pulses was performed in air on cobalt cemented tungsten carbide by means of a Ti : sapphire laser (800 nm, 100 fs). Small and moderate fluences (2, 5, 10 J/cm2) and up to 5×104 pulses per irradiated spot were used to drill holes with aspect ratios up to 10. Cross-section cuts from laser-irradiated samples were produced and they were analysed with optical microscopy and SEM. EDX analyses were carried out on selected zones. Quasi-cylindrical holes were found for 2 J/cm2, whereas for 5 and 10 J/cm2 irregular shapes (lobes, bottoms wider than hole entrances) were found to occur after a given number of incident pulses. Layers with modified structure were evidenced at pore walls. SEM revealed a denser structure, while EDX analyses showed uniform and almost similar contents of W, C, and Co in these layers. As a direct application, patterning of coated WC-Co was carried out with 2 J/cm2 and 100 pulses per pore. The resulted surfaces were tribologically tested and these tests revealed an improved friction and wear behaviour.

Polycrystalline SiGe is attracting more and more attention in micro and optoelectronics devices both at industrial and university level. Research on both devices and material growth techniques continues at a very rapid pace in the scientific world. Low cost production techniques, capable to produce such alloys with uniform and controlled grain size, becomes of particular attention. Excimer laser crystallization has proved to be a valuable how thermal budget technique for amorphous silicon crystallization. Its main advantages are the high process quality and reproducibility joint to the possibility of tailoring the grain sizes both in small selected regions and in large areas. This technique is here applied for producing poly-SiGe alloys from amorphous SiGe films deposited on glass.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.