We study the QCD phase diagram at finite temperature and baryon chemical potential by relating the behavior of the light-quark condensate to the threshold energy for the onset of perturbative QCD. These parameters are connected to the chiral symmetry restoration and the deconfinement phase transition, respectively. This relation is obtained in the framework of finite energy QCD sum rules at finite temperature and density, with input from Schwinger-Dyson methods to determine the lightquark condensate. Results indicate that both critical temperatures are basically the same within some 3% accuracy. We also obtain bounds for the position of the critical end point, µBc 300 MeV and Tc 185 MeV.

Cereal Chem. 84(2): [186][187][188][189][190][191][192][193][194] In this report, the effect of temperature on the calcium content of Quality Protein Maize (QPM H-368C) during the nixtamalization process as a function of the steeping time for three cooking temperatures (72, 82, and 92°C) is presented. Also, for the first time, we report in physicochemical terms the end of the cooking stage during the nixtamalization process that was established when the moisture content in corn kernels reached a value of 36% (w/w) with a lime concentration of 1% (w/v), independent of the cooking temperature. Atomic absorption spectroscopy was used to determine the calcium concentration in the whole kernel and in its different anatomical components (pericarp, endosperm, and germ) as well as in 10% of the outermost layers, the next 10%, and the remaining 80% of the endosperm as a function of the steeping time. It was found that if the cooking temperature increases, the calcium content increases also. For steeping times in the range of 5-7 hr, a relative maximum was found in the calcium contents of 0.24, 0.21, and 0.18% (w/w) in QPM H-368 flours at 92, 82, and 72°C, respectively. Calcium was found in the most external layers in the endosperm and minimum diffusion occurs in the internal 80%. Phosphorous was measured by using UV spectroscopy and the results showed that it remains constant at 0.24% throughout the process. Scanning electron microscopy analysis was used to explain the calcium ion diffusion in the kernel. The physical changes in the pericarp govern the calcium diffusion process.

Selected raw materials, surface treatment, and control of the internal flow fundamentals are applied to manufacture an anticlogging nozzle. This nozzle is compared with another one manufactured with a conventional alumina-graphite (AG) composite in a plant trial. The two nozzles, with and without clogging, are replicated with plastic and rubber materials and the flows, under unclogged and clogged conditions, are characterized using water modelling and mathematical simulations. The new nozzle material yields considerably less clogging than the nozzle with the conventional AG after casting four heats, yet, there is still clogging. Flow patterns, because of clogging, change radically and represent serious conditions for slab integrity and the productivity of the caster.

No abstract

This report shows the effect of temperature (72, 82, and 92°C) during the cooking stage and steeping time (0, 1, 3, 5, 7, 9, 11, 13, and 15 hr) on calcium and phosphorus contents in nixtamalized corn flours obtained by the traditional nixtamalization process (NCF). In addition, calcium and phosphorus contents in industrial nixtamalized corn flours were analyzed for comparative purposes. Atomic absorption spectroscopy and UV‐vis spectroscopy methods were used to study the calcium and phosphorus contents as well as the Ca2+/P ratio in NCF and industrial nixtamalized corn flours. Additionally, deposition and identification of calcium compounds in the nixtamalized corn pericarp were analyzed by low‐vacuum scanning electron microscopy, energy dispersive spectrometry, and X‐ray diffraction techniques. Dry matter loss in NCF is also reported. As the temperature increased, Ca2+ content was enhanced, while the phosphorus content decreased with statistical differences (P ≤ 0.05) between thermal treatments. Ca2+ content in industrial nixtamalized corn flours was significantly lower (P ≤ 0.05) than that of NCF. On the other hand, no statistical differences (P ≤ 0.05) were found between phosphorus content in commercial nixtamalized corn flours and NCF. Calcium compounds, identified as calcite, were detected in corn pericarp. Statistical differences (P ≤ 0.05) were observed in phosphorous content in NCF obtained at different cooking temperatures. In addition, a decrease in phosphorus levels significantly correlated with the steeping time at 92°C (r = –0.91). At 72, 82, and 92°C, the average Ca2+/P ratio in NCF was 0.45 ± 0.03, 0.61 ± 0.05, and 0.82 ± 0.05, respectively, indicating a correlation between this parameter and the cooking temperature. However, no correlation was found between the Ca2+/P ratio and the steeping time. This behavior is attributed to calcium attached to corn kernel. In commercial nixtamalized corn flours, the Ca2+/P ratio was significantly lower (P ≤ 0.05) than that of NCF. There was a significant correlation (P ≤ 0.01) between dry matter loss and steeping time (r = 0.99) in NCF, this fact influenced the Ca2+/P ratio due to the calcium attached to pericarp. At 82 and 92°C, maximum values of Ca2+/P ratio were detected in NCF at 7 hr of steeping time and at 9 hr at 72°C. These results can be used with industrial purposes to assess a maximum calcium‐to‐phosphorus ratio, and at the same time, to avoid the loss of pericarp to increase the functional properties of NCF.

Nozzle clogging is still a concern for steel makers due to the high-quality requirements and productivity in the continuous casting. The present work studies the factors involved in the inclusion deposition at the nozzle wall using numerical and analytical techniques. For this, a detailed fluid dynamic analysis inside the nozzle in a coupled tundish-mold system is undertaken. The results show that the inclusions reaching the nozzle, only 30% get deposited along its walls mainly at the upper tundish nozzle (UTN) and at the submerged entry nozzle (SEN) ports. These areas of higher deposition are identified close to a low static pressure and a high turbulent kinetic energy dissipation zones. The high-energy dissipation induces a fluctuant velocity increment; consequently, the mean flow velocity increases forcing a reduction of the static pressure in order to preserve the mechanical energy balance. This mechanical energy imbalance is identified as mechanical energy dissipation being recognized by an increment in the vorticity and quantified by an additional term into Bernoulli equation. This complex phenomenon induces zones of high turbulent flow from which the inclusions tend to move toward lower turbulence regions, explaining why the inclusions get deposited in these two typical zones promoting the deleterious clogging phenomenon.

We study the phase diagram of quantum chromodynamics (QCD). For this purpose we employ the Schwinger-Dyson equations (SDEs) technique and construct a truncation of the infinite tower of equations by demanding a matching with the lattice results for the quark-anti-quark condensate at finite temperature (T ), for zero quark chemical potential (µ), that is, the region where lattice calculations are expected to provide reliable results. We compute the evolution of the phase diagram away from T = 0 for increasing values of the chemical potential by following the evolution of the heat capacity as a function of T and µ. The behavior of this thermodynamic variable clearly demonstrates the existence of a cross-over for µ less than a critical value. However, the heat capacity develops a singularity near µ ≈ 0.22 GeV marking the onslaught of a first order phase transition characterized by the existence of a critical point. The critical line continues until µ ≈ 0.53 GeV where Tc = 0 and thus chiral symmetry is finally restored.

We study chiral symmetry breaking for relativistic fermions, described by a parity-violating Lagrangian in 2 þ 1-dimensions, in the presence of a heat bath and a uniform external magnetic field. Working within their four-component formalism allows for the inclusion of both parity-even and -odd mass terms. Therefore, we can define two types of fermion antifermion condensates. For a given value of the magnetic field, there exist two different critical temperatures which would render one of these condensates identically zero, while the other would survive. Our analysis is completely general: it requires no particular simplifying hierarchy among the energy scales involved, namely, bare masses, field strength, and temperature. However, we do reproduce some earlier results, obtained or anticipated in literature, corresponding to special kinematical regimes for the parity conserving case. Relating the chiral condensate to the one-loop effective Lagrangian, we also obtain the magnetization and the pair production rate for different fermion species in a uniform electric field through the replacement B ! ÀiE.