Behaviour of Impurities during Electron Beam Melting of Copper Technogenic Material

The current study presents the electron beam melting (EBM) efficiency of copper technogenic material with high impurity content (Se, Te, Pb, Bi, Sn, As, Sb, Zn, Ni, Ag, etc.) by means of thermodynamic analysis and experimental tests. On the basis of the calculated values of Gibbs free energy and the physical state of the impurity (liquid and gaseous), a thermodynamic assessment of the possible chemical interactions occurring in the Cu-Cu₂O-Me_x system in vacuum in the temperature range 1460–1800 K was made. The impact of the kinetic parameters (temperature and refining time) on the behaviour and the degree of removal of impurities was evaluated. Chemical and metallographic analysis of the obtained ingots is also discussed.     

The types and timing of the degenerative changes seen in the cysts during and after benzimidazole treatment of cystic echinococcosis

In a large-scale Bulgarian study, 122 patients with abdominal and/or lung echinococcosis were randomly selected for treatment with albendazole or mebendazole. The main aims were to evaluate the effect of each drug on the hydatid cysts, to follow the changes in cyst morphology during and after treatment, and to determine how quickly each drug produced the first, detectable, degenerative changes in the cysts. Follow-up was based on periodic ultrasonography, chest radiography and computed tomography. The abdominal cysts were categorised as small (<5 cm in diameter) or large. As albendazole treatment had effects that were almost identical to those of mebendazole treatment, the results for the two drugs were combined. In the lungs and, particularly, in the abdomen, the size of the cysts being treated influenced the character and timing of the degenerative changes seen in them.The initial change seen in each abdominal cyst was detachment of the endocyst, which occurred 1-3 months (small cysts) or 2-5 months (large cysts) after the initiation of treatment (P<0.05). The abdominal cysts then developed a hyper-echoic/hyper-dense appearance, became smaller, and finally disappeared 3.3-9.3 months (small cysts) or 5.6-13.9 months (large cysts) after treatment began (P<0.05).The first degenerative change noted in the lung cysts was cyst rupture, which occurred as early as day 10 of therapy but was generally observed 1 or 2 months after treatment began. After their complete evacuation, the ruptured lung cysts shrank and became deformed, some disappearing within 5-9 months of the initiation of treatment. The degenerative changes recorded, which began significantly earlier in the lung cysts than in abdominal cysts, indicate serious damage to the cysts and the parasiticidal, curative effect of each of the two benzimidazoles employed.     

Factors influencing the response to chemotherapy in human cystic echinococcosis.

As the effectiveness of mebendazole and albendazole in patients with echinococcosis has been found to vary, we investigated some of the factors likely to be responsible. A total of 79 patients who were treated with mebendazole (44 patients) or albendazole (35 patients) were included in the study. Evaluation of the treatment results was based on the changes in cyst morphology, as evidenced by the results of X-ray radiography, sonography, and computed tomography, and on analysis of the findings in relation to parasitic and drug factors. The response of cysts according to their site did not vary much, with the exception of the poor response of bone cysts. A more important factor seems to be cyst size, since the treatment was more efficacious against smaller and younger cysts. The presence of daughter cysts should be regarded as an unfavourable factor for treatment response. Cyst multiplicity did not present insurmountable difficulties, provided the cysts were small and a prolonged course of therapy was undergone. The choice of drug used for the therapy was important, with the results supporting the advantage of albendazole. In planning the chemotherapy of hydatid disease, factors such as cyst condition and drug used should therefore be taken into consideration.     

Evaluation of response to chemotherapy of human cystic echinococcosis

Fifty-five patients with echinococcosis were treated with mebendazole (30) and albendazole (25). To determine changes in cyst morphology and to evaluate the varying degree of response, progress during follow-up was shown by radiography, computerized tomography and ultrasonography. Persistence of cysts without any change in the morphology and cyst enlargement were taken as criteria for unsuccessful treatment. Development of echogenic foci and increase in density of cyst fluid were considered as a therapeutic effect. Changes in cyst wall such as thickening and deposition of calcium and detachment of the cyst membrane may also indicate response. An essential criterion, for a positive drug effect, was cyst size reduction as well as shape deformation. However, the most convincing and reliable criterion was the complete disappearance of hydatid cysts. Comparative assessment of the therapeutic effect of the two drugs favoured albendazole.     

Effect of mebendazole on human cystic echinococcosis: the role of dosage and treatment duration

Fifty-three patients with single, multiple and/or multi-organ hydatid cysts were treated with mebendazole, in varying dosages (30-70 mg/kg.day) and over varying periods (6-24 months). Treatment failure was recorded if the mebendazole had no apparent effect on cyst morphology (monitored by radiology, ultrasonography and computed tomography) or only a parasitostatic effect (characterized by mixed and transitory, hypo- and hyper-echoic changes in the lesions). Cure was indicated by a parasitocidal effect (characterized by a totally echogenic picture, increased density of the cyst contents, reduction in the size or complete disappearance of the cysts, complete detachment of the endocysts and/or calcification of the cyst wall). Treatment failure was seen in about 40% of the patients and cure in about 38%; the other 23% had an intermediate result considered as an improvement. Cure rates increased both with dosage and duration, daily dosages of 60-70, 50 and 30-40 mg/kg curing 48%, 33% and 25%, respectively. The pre-treatment condition of any cysts should be taken into consideration when determining dosage and treatment duration.     

Electron Beam Melting and Refining of Metals: Computational Modeling and Optimization

Computational modeling offers an opportunity for a better understanding and investigation of thermal transfer mechanisms. It can be used for the optimization of the electron beam melting process and for obtaining new materials with improved characteristics that have many applications in the power industry, medicine, instrument engineering, electronics, etc. A time-dependent 3D axis-symmetrical heat model for simulation of thermal transfer in metal ingots solidified in a water-cooled crucible at electron beam melting and refining (EBMR) is developed. The model predicts the change in the temperature field in the casting ingot during the interaction of the beam with the material. A modified Pismen-Rekford numerical scheme to discretize the analytical model is developed. These equation systems, describing the thermal processes and main characteristics of the developed numerical method, are presented. In order to optimize the technological regimes, different criteria for better refinement and obtaining dendrite crystal structures are proposed. Analytical problems of mathematical optimization are formulated, discretized and heuristically solved by cluster methods. Using important for the practice simulation results, suggestions can be made for EBMR technology optimization. The proposed tool is important and useful for studying, control, optimization of EBMR process parameters and improving of the quality of the newly produced materials.     

Experience in the chemotherapy of severe,inoperable echinococcosis in man

Summary The effect of albendazole and mebendazole was studied in 25 patients with severe, multiple, inoperable echinococcosis. Eleven patients were treated with albendazole 10 mg/kg/day for four courses of 30 days with 15-day drug-free intervals and 14 with mebendazole 50–70 mg/kg/day continuously for between 6 and 24 months. The determination of cyst response was based on the changes in cyst appearance as seen by radiography, ultrasound and computed tomography. Albendazole and mebendazole were found to have favourable effects in patients with severe, inoperable hydatid disease, although the degree of response varied. Treatment with albendazole was successful in seven cases, partially successful in two, and failure was noted in the other two patients. In patients treated with mebendazole, success was established in three, partial success in five and failure in six cases. The differences in response were mainly associated with cyst condition and the drug used. In some cases long-term therapy and retreatment should be recommended.

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Erfahrung mit der Chemotherapie der schweren, inoperablen Echinokokkose des Menschen

Zusammenfassung Die Wirkung von Albendazol und Mebendazol wurde bei 25 Patienten mit schwerer, multipler und inoperabler Echinokokkose untersucht. Elf Patienten wurden mit Albendazol in der Dosierung von 10 mg/kg Körpergewicht/die über 4 Kurse von 30 Tagen mit 15 Tagen zwischen Kursen und 14 Patienten mit Mebendazol 50–70 mg/kg/Körpergewicht/die über 6–24 Monate behandelt. Die Beurteilung der Therapiewirkung wurde aufgrund der Änderungen der röntgenologischen, sonographischen und computertomographischen Befunde durchgeführt. Es wurde festgestellt, daß Albendazol und Mebendazol eine günstige therapeutische Wirkung bei Patienten mit schwerer, inoperabler Echinokokkose haben. Die Therapie mit Albendazol war bei sieben Patienten erfolgreich, erzielte Teilerfolge bei zwei Patienten und war erfolglos bei zwei weiteren Patienten. Mit Mebendazol wurde bei drei Patienten ein Therapieerfolg, bei fünf ein Teilerfolg und in sieben Fällen ein Mißerfolg beobachtet. Die Unterschiede in den therapeutischen Ergebnissen wurden hauptsächlich mit dem Zustand der Zysten, aber auch mit dem benutzten Medikament in Verbindung gebracht. Bei manchen Patienten war eine längere und wiederholte Therapie nötig.