Onsager approach to the one-dimensional solidification problem and its relation to the phase-field description.

We give a general phenomenological description of the steady-state 1D front propagation problem in two cases: the solidification of a pure material and the isothermal solidification of two-component dilute alloys. The solidification of a pure material is controlled by the heat transport in the bulk and the interface kinetics. The isothermal solidification of two-component alloys is controlled by the diffusion in the bulk and the interface kinetics. We find that the condition of positive-definiteness of the symmetric Onsager matrix of interface kinetic coefficients still allows an arbitrary sign of the slope of the velocity-concentration line near the solidus in the alloy problem or of the velocity-temperature line in the case of solidification of a pure material. This result offers a very simple and elegant way to describe the interesting phenomenon of a possible non-single-value behavior of velocity versus concentration that has previously been discussed by different approaches. We also discuss the relation of this Onsager approach to the thin-interface limit of the phase-field description.

Solidification along the interface between demixed liquids in monotectic systems.

The steady-state solidification along the liquid-liquid interface in the monotectic system is discussed. A boundary-integral formulation describing the diffusion in the two liquid phases is given and the corresponding equations for the three interfaces (two solid-liquid interfaces and one liquid-liquid interface) are solved. Scaling relations are extracted from the results and supported by analytic arguments in the limit of small deviation from the monotectic temperature. We present also a complementary phase-field simulation, which proves the stability of the process.

Pattern formation during diffusional transformations in the presence of triple junctions and elastic effects.

We compare different scenarios for dendritic melting of alloys with respect to the front propagation velocity. In contrast to conventional dendritic growth, selection can here be also due to the presence of a grain boundary or coherence strains, and the propagation speed is higher. The most favorable situation is partial melting, where two parabolic fronts, one melting and one solidifying interface, are moving together, since the process is then determined by diffusion in the thin liquid layer. There, and also in phase field simulations of melting in peritectic and eutectic systems, we observe a rotation of the triple junction relative to the growth direction. Finally, we discuss the role of elastic effects due to density and structural differences on solid-state phase transformations, and we find that they significantly alter the selection principles. In particular, we obtain free dendritic growth even with isotropic surface tension. This is investigated by Green's function methods and a phase field approach for growth in a channel and illustrated for the formation of a twin phase.

Velocity selection problem in the presence of the triple junction.

Melting of a bicrystal along the grain boundary is discussed. A triple junction plays a crucial role in the velocity selection problem in this case. In some range of the parameters an entirely analytical solution of this problem is given. This allows us to present a transparent picture of the structure of the selection theory. We also discuss the selection problem in the case of the growth of a "eutectoid dendrite."

Velocity-selection problem for combined motion of melting and solidification fronts.

We discuss a free boundary problem for two moving solid-liquid interfaces that strongly interact via the diffusion field in the liquid layer between them. This problem arises in the context of liquid film migration (LFM) during the partial melting of solid alloys. In the LFM mechanism the system chooses a more efficient kinetic path which is controlled by diffusion in the liquid film, whereas the process with only one melting front would be controlled by the very slow diffusion in the mother solid phase. The relatively weak coherency strain energy is the effective driving force for LFM. As in the classical dendritic growth problems, also in this case an exact family of steady-state solutions with two parabolic fronts and an arbitrary velocity exists if capillary effects are neglected [D. E. Temkin, Acta Mater. 53, 2733 (2005)]. We develop a velocity-selection theory for this problem, including anisotropic surface tension effects.

Complete bony fusion of the mandible to the zygomatic complex and maxillary tuberosity: case report and review.

Congenital craniofacial disorders represent approximately 20% of all birth defects. One of these disorders is syngnathia, of which only 24 cases have been reported since 1936. Twenty cases involved fusion of the alveolar processes of the maxilla and mandible. Only four are similar to the presented case, which includes bony fusion of the ascending ramus of the mandible to the zygomatic complex and the posterior part of the maxilla. This case report will present details from the 23rd week of gestation to 8 months of age when the infant underwent the first attempt to free the syngnathia. The literature is discussed and a causative mechanism and new classification are proposed.

[Congenital granular cell epulis].

Congenital granular cell epulis is an uncommon pedunculated tumor of the upper alveolar mucosa found only in newborns. The lesion is not usually associated with other congenital deformities, but presents a major esthetic problem and interferes with nursing. We present a case of a double epulis, 7 cm in diameter, in a 2-day-old girl. Treatment is simple excision, and no recurrences have been reported. The lesion must be differentiated from granular cell myoblastoma.

Unilateral enlargement of the masseter muscle.

Benign hypertrophy of the masseter muscle is a relatively uncommon condition which may occur unilaterally or bilaterally. The etiology of the ailment is unclear in the majority of cases, and the histopathological features are usually those of normal muscle. A case of unilateral masseter muscle enlargement is described in a 19-year-old Arab male. The histopathological findings were compatible with a mild myopathic disorder. The characteristics, differential diagnosis, etiology, treatment and histopathological features of masserteric hypertrophy are discussed.

Burkitt's lymphoma in Israel.

A case is described of Burkitt's lymphoma in a nine-year-old Arab boy. The presenting symptom was swelling of the right maxilla, originally diagnosed as a dento-alveolar abscess. The clinical features of African and American Burkitt's lymphoma are compared, and the occurrence of the tumor mainly in the Arab population of Israel is noted.