Modeling and Measurements of Heat Transfer Phenomena in Two-Phase PbSn Alloy Solidification in an External Magnetic Field

The main aim of this work is to study numerically the influence of an external magnetic field on the solidification processes of two-component materials. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in a magnetic field is presented. The model includes mass, momentum, energy and species mass conservation equations written in compressible form and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone, which is treated by means of a porous medium approach. The volume fraction of liquid and solid phases, respectively, is calculated from a 2D approximation of the phase diagram. The results of calculation are compared with experimental data.     

The effect of pulsed electrical currents on the formation of macrosegregation in solidifying Al–Si hypoeutectic phases

Within this study, we conducted experimental investigations focusing on the formation of macrosegregation in Al-7wt-%Si alloys exposed to electric current pulses (ECP) during solidification. The distribution of eutectic phase was measured on various sections of the solidified samples. The results do not show the formation of reproducible segregation pattern. This finding can be attributed to the specific pattern and the turbulent character of the flow generated by the ECP treatment, the equiaxed growth of free-moving crystals and a non-symmetric distribution of the electromagnetic force due to an uneven wetting of the electrodes. An increasing input of energy by ECP intensifies the melt flow and increases the variations of phase distribution over a longitudinal section.     

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Ohne Zusammenfassung VDI     

Sexual maturation in East German girls

According to the internationally accepted classification (Tanner, 1962; van Wieringen, 1971), sexual maturation was investigated in 8703 healthy East German girls by means of the status quo method and probit regression analysis. The third, 50th and 97th centiles were calculated for the development of breasts, axillary and pubic hair, and the shape of the hips. The findings were compared with those of recent studies from different European countries. Special attention was paid to the stages at the beginning and at the end of sexual maturation, e.g. B2/B5, AH2/AH3, etc.     

Expression of apoptosis-regulating proteins and outcome of esophageal cancer patients treated by combined therapy modalities

The present study retrospectively examines the correlation between the outcome of patients with locally advanced esophageal squamous cell carcinoma (LAEC) after multimodal treatment (radiochemotherapy +/- surgery) and the expression of apoptosis-regulating proteins in pretherapeutic biopsies. Thirty-eight patients with LAEC who took part in a prospective multicentric trial received radiochemotherapy, optionally followed by surgery. Pretreatment tumor biopsies were immunohistochemically investigated for expression of p53, Bcl-2, Bax (bcl-2-associated X protein), and Bcl-X(L) (bcl-2-related X protein). The overall expression of p53, Bcl-2, Bax, and Bcl-X(L) was 52.6, 57.9, 100, and 97.4% respectively. Tumors without p53 expression and tumors with weak Bcl-X(L) expression showed response to chemotherapy more frequently (55.6 and 52.6%, respectively) than tumors positive for p53 expression and tumors with strong Bcl-X(L) expression (30.0 and 31.6%, respectively); however, these differences did not attain statistical significance. No correlations were found between the expression of Bcl-2 and Bax and the response to chemotherapy. In patients treated by radiochemotherapy and surgery, p53-negative tumors showed a significantly better outcome than p53-positive tumors (mean survival, 31.1 months versus 11.3 months; P = 0.0378). Additionally, a more favorable outcome was observed in tumors positive for Bcl-2 (not significant), whereas no differences in survival were observed in relation to the expression of Bax or Bcl-X(L). No differences in survival were observed in patients treated by radiochemotherapy without subsequent resection therapy in relation to the expression of apoptosis-regulating proteins. Immunohistochemical examination of pretherapeutic tumor biopsies for expression of apoptosis-regulating proteins may help to identify patients with LAEC who may benefit from multimodal treatment and those who may not.     

Basaloid squamous cell carcinoma of the esophagus: diagnosis and prognosis

BACKGROUND: Basaloid squamous cell carcinoma (BSCC) is a recently recognized, poorly differentiated variant of squamous cell carcinoma (SCC), which is located predominantly in the upper aerodigestive tract. METHODS: In this study, clinical and pathologic parameters of 17 BSCCs and 133 typical SCCs of the esophagus that underwent potentially curative resection (no distant metastases, no residual tumor) were compared. In addition, light microscopic, electron microscopic, and immunohistochemical features of BSCC were investigated, to determine whether this type of carcinoma could be differentiated from other poorly differentiated carcinomas of the esophagus. RESULTS: Light microscopic study showed that BSCC was composed of relatively small tumor cells, arranged in solid lobules with abundant comedo-type necrosis. BSCC was almost invariably accompanied by areas of concomitant typical SCC, foci of squamous cell differentiation, and/or severe squamous cell dysplasia or carcinoma in situ of the adjacent mucosa. Ultrastructurally, BSCC inconsistently showed features of squamous cell differentiation. Immunohistochemically, BSCC displayed poor reactivity for antibodies against wide-range cytokeratins and cytokeratin subtypes that are typical of squamous cell epithelia (cytokeratin 13 and cytokeratin 14). Infrequently, expression of Leu7, smooth muscle actin, and S-100 protein was found. In comparison with typical SCC, the characteristic features of BSCC were older patient age, higher proliferative activity (MIB-1 labelling index), and higher apoptotic indices. No differences were found with regard to pT classification, pN classification, tumor size, blood vessel invasion, lymphatic vessel invasion, neural invasion, or patient gender. Moreover, no differences in overall survival rates were found. CONCLUSIONS: BSCC is a distinct histopathologic variant of SCC, characterized by a poor degree of differentiation and high proliferative activity. However, after potentially curative resection, the prognosis of patients with BSCC of the esophagus does not differ from that of patients with typical SCC.     

Odour abatement in the integrated reactor concept for simultaneous treatment of liquid and solid pig manure fractions.

New technologies are needed for manure treatment that can capture nutrients, reduce emissions of ammonia and nuisance odours, and kill harmful pathogens. A reactor concept was developed for simultaneous treatment of separately collected liquid and solid fractions of pig manure. The liquid fraction is concentrated by evaporating the water using energy from the composting system and at the same time scrubbing ammonia from the composting off-gas by acidifying the urine to pH 4 with nitric acid. This results in two marketable products, a concentrated liquid nitrogen fertiliser (NH4NO3) without phosphorus, and a stabilised, solid organic fertiliser, which is free of pathogens and weeds. By connecting the two reactor systems, emissions of ammonia and odours are abated as ammonia emitted from the composting is trapped in the liquid fraction and odorous compounds emitted from the liquid are degraded in the composting reactor. The concept was physically simulated by coupling a 80-L compost reactor to a 10-L bubble column. Operation of the bench-scale system showed that the concept is very promising. All nutrients were captured, and emissions of ammonia and odours were almost completely abated.     

Rheological and structural characterization of tomato paste and its influence on the quality of ketchup

Three hot break tomato pastes were investigated to determine the effect of their characteristics on the properties of tomato ketchup, processed in an industrial-scale facility (i.e. diluted, heated, homogenized and cooled). Pastes and ketchups were characterized by particle size distribution, volume fraction, and rheological behavior in steady and dynamic shear. The ketchups were also subjected to sensory assessment. The processing of pastes into ketchups induced large structural changes, which were reflected in all parameters studied. The volume fraction of solids (φ) accurately reflected the changes that the paste suspensions underwent during processing and it appeared to be a good predictor of the flow behavior of both the pastes and the ketchups. The corresponding flow curves were found to be well described by the Carreau model in a large range of shear rates and concentrations. However, the rheological characteristics of the commercial pastes studied did not directly correlate to those of the corresponding ketchups. Instead, our results suggest that the change in structure induced by processing might be governed by other properties of the paste, such as the fraction of small and large particles and their sensitivity to breakage, together with the viscosity of the aqueous phase.