Directional solidification of Pb-Sn eutectics with vibration

Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The number of grain boundaries was increased by vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model

Directional solidification of Pb-Sn eutectic with vibration

Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model

Inflação, Crescimento e Desenvolvimento: como a macroeconomia neoclássica impede o desenvolvimento

O uso de políticas ortodoxas anti-inflacionárias tem impedido a adoção tanto de estratégias de crescimento como de desenvolvimento. Constitui a base teórica neoclássica com objetivo de afastar o Estado da administração do movimento do capital não permitindo a realização de políticas fiscal ou monetária expansionistas, bem como de políticas cambiais estratégicas. Está envolta em uma ideologia pré-keynesiana baseada no comportamento hipotético do agente racional maximizador, na teoria quantitativa da moeda, num mundo em equilíbrio walrasiano, conceitos modernizados para que “expectativas racionais” transformem o medo inflacionário em ideologia contra a intervenção públic

Crise: um problema conjuntural ou da lógica da acumulação mundial?

The idea of this text is to explore that the current financial crises is the manifestation of the exhaustion of the global capital accumulation process (globalization) established by determined standard (mundialização) created in the postwar period. The first signals of this exhaustion had appeared in the 70s. The liberalization policies imposed by the proper capital from that period in order to maintain its profits, if of one hand had allowed certain global capital-productive reorganization, of another one had opened a wide space for the fictitious valuation of the capital that now bursts in crisis.Neste texto, explora-se a ideia de que a crise financeira atual é a manifestação do esgotamento do processo de acumulação mundial de capital fundado em um determinado padrão (mundialização) no pós-guerra. Os primeiros sinais desse esgotamento apareceram nos anos 1970. As soluções liberalizantes impostas pelo próprio capital a partir de então para buscar manter sua rentabilidade, se, de um lado, permitiram certa reestruturação produtiva mundial, de outro, abriram um amplo espaço para a valorização fictícia do capital que ora irrompe em crise

Influence of convection on microstructure

The mechanism responsible for the difference in microstructure caused by solidifying the MnBi-Bi eutectic in space is sought. The objectives for the three year period are as follows: (1) completion of the following theoretical analyses - determination of the influence of the Soret effect on the average solid composition versus distance of off-eutectic mixtures directionally solidified in the absence of convection, determination of the influence of convection on the microstructure of off-eutectic mixtures using a linear velocity profile in the adjacent melt, determination of the influence of volumetric changes during solidification on microconvection near the freezing interface and on microstructure, and determination of the influence of convection on microstructure when the MnBi fibers project out in front of the bismuth matrix; (2) search for patterns in the effect of microgravity on different eutectics (for example, eutectic composition, eutectic temperature, usual microstructure, densities of pure constituents, and density changes upon solidification); and (3) determination of the Soret coefficient and the diffusion coefficient for Mn-Bi melts near the eutectic composition, both through laboratory experiements to be performed here and from data from Shuttle experiments

Influence of convection on microstructure

In eutectic growth, as the solid phases grow they reject atoms to the liquid. This results in a variation of melt composition along the solid/liquid interface. In the past, mass transfer in eutectic solidification, in the absence of convection, was considered to be governed only by the diffusion induced by compositional gradients. However, mass transfer can also be generated by a temperature gradient. This is called thermotransport, thermomigration, thermal diffusion or the Soret effect. A theoretical model of the influence of the Soret effect on the growth of eutectic alloys is presented. A differential equation describing the compositional field near the interface during unidirectional solidification of a binary eutectic alloy was formulated by including the contributions of both compositional and thermal gradients in the liquid. A steady-state solution of the differential equation was obtained by applying appropriate boundary conditions and accounting for heat flow in the melt. Following that, the average interfacial composition was converted to a variation of undercooling at the interface, and consequently to microstructural parameters. The results obtained show that thermotransport can, under certain circumstances, be a parameter of paramount importance

3(Amino-1,1-hydroxypropylidene) bisphosphonate (APD) for hypercalcaemia of breast cancer.

The effect of a single dose of APD on hypercalcaemia has been studied in advanced breast cancer. Twenty-five patients were rehydrated intravenously for 48 h. Twenty-three remained hypercalcaemic and received 5-15 mg APD as a 2 h infusion. Eighteen patients achieved normocalcaemia, 15 after a dose of less than or equal to 15 mg. One patient died within 24 h from rapidly advancing disease and 4 remained hypercalcaemic. Urinary calcium excretion increased during rehydration as glomerular function improved and tubular reabsorption of calcium fell. After APD, calcium excretion fell to normal in 22/24 patients reflecting inhibition of bone resorption. Hydroxyproline excretion remained high. The effect of a single dose of APD on hypercalcaemia lasted a median of 11 days (range 7-17). Transient fever occurred in 2 patients, but there were no other side effects. The possibility of long-term control of osteolysis using a 2 weekly schedule of APD administration is now being studied

The clinical course of bone metastases from breast cancer.

All patients with carcinoma of the breast seen in this Unit since 1970 were reviewed to study the incidence, prognosis, morbidity and response to treatment of bone metastases. The biological characteristics of the primary tumour were compared in patients relapsing first in bone or liver. Sixty-nine percent of patients dying with breast cancer had bone metastases and bone was the commonest site of first distant relapse. Bone relapse was more common in receptor positive or well differentiated (grade 1) tumours. The median survival was 24 months in those with disease apparently confined to the skeleton compared with 3 months after first relapse in liver. Ten percent of patients with breast cancer developed hypercalcaemia. All had metastatic disease and 85% had widespread skeletal involvement. Fifteen percent of patients with disease confined to the skeleton developed hypercalcaemia. The response in bone to primary endocrine therapy, and chemotherapy, was apparently less than the overall response achieved. A large proportion had apparently static disease reflecting the insensitivity of the UICC assessment criteria. The duration of survival in these patients was similar to responding patients, suggesting a tumour response may occur in the absence of discernable radiological evidence of healing