Texture and graphitization behaviour of fluid coke

The texture, its changes with heat-treatments and with oxidation, and the graphitization behaviour of the fluid coke were investigated using polarized light microscopes, scanning electron microscopes and X-ray diffraction. The fluid coke as received had the homogeneous particle size of 0·1–0·2 mm. It consisted of two kinds of particles in almost equal amounts: one type with relatively smooth surfaces and showing crossed extinction contours for cross cuts, and the second type with very rough surfaces and radial extinction contours. In the former ones, the graphite-like layers seem to align approximately concentrically like that of onions. In the latter ones, regions with large graphite-like layers are highly oriented but those with small layers orient randomly being arranged like in a chrysanthemum flower. Formation of cracks in the particles heat-treated under normal pressure was observed and is explained as due to the texture. The graphitizability of the coke is very poor, c₀-spacing decreasing only to 6·78 Å after 2780°C-treatment under normal pressure and only to 6·82–6·84 Å after 2000°C-treatment under 5 kbar. The characteristic textures of the particles, onion- and chrysanthemum-like are still retained after heat-treatment under 5 kbar.     

Usefulness of argyrophilic nucleolar organizer staining for predicting prognosis of patients with recurrent soft tissue sarcoma

Local recurrence of tumor is a common phenomenon in soft tissue sarcoma (STS) and may be accompanied by an increase in malignant potential. In the present study, an increase of proliferative activity in recurrent tumors compared to primary tumors was observed using a silver stain for nucleolar organizer regions (AgNOR), and its implication for predicting prognosis is assessed. 44 patients with STS showing local tumor recurrence were selected. Local recurrence was defined as new tumor growth more than 2 months after the initial surgery in the same region where the primary tumor occurred. All patients received surgery, followed in 11 patients by adjuvant radiotherapy and/or chemotherapy. The histologic subtype was malignant fibrous histiocytoma in 22 cases, synovial sarcoma in 5, leiomyosarcoma in 4, liposarcoma in 3, malignant schwannoma in 3, and others in 7. The interval between initial surgery and local recurrence ranged from 2 to 72 months. No patients changed from one histological subtype to another. Histological changes included an increase in mitosis, cellularity, and sclerosis in 43.2, 31.8, and 27.3%, respectively. The AgNOR count (mean +/- SD) in recurrent tumors (7.22 +/- 2.59) was significantly higher than that in primary tumors (5.58 +/- 2.28; p < 0.0057), clearly showing a tendency for an increase in proliferative activity during recurrence. The 5-year survival rate of patients with a marked increase (> 4) in AgNOR count (16.7%) was worse than with minor to moderate increases (60.0%; p < 0.02). Marked AgNOR increase was more frequently observed in the tumors located in the head and neck and retroperitoneum (40%) than in other sites (9%). Irrespective of the primary site of tumors, a marked AgNOR increase resulted in an unfavorable prognosis. Multivariate analysis of change in histologic factors including AgNOR, cellularity, mitotic counts, pleomorphism, myxoid change, necrosis, sclerosis, and tumor size showed that increase of AgNOR counts was significant (p < 0.05). The present findings suggest that AgNOR counts can be used as a prognostic factor in recurrent STS.     

Applying of ultrasonic waves on brazing of alumina to copper using Zn-Al filler alloy

Ultrasonic waves were applied during brazing of alumina to copper, The intensity of ultrasonic wave was 1 kW and 18 kHz and the aim of this work was to study the effect of the ultrasonic wave and brazing temperature on the properties of the braze joint between alumina and copper using Zn-Al alloys as filler metal.First the alumina was metallized by applying on ultrasonic wave in a Zn-Al braze bath. Then the metallized alumina was brazed with copper using the same filler alloy. The joining mechanism was investigated by measuring the joining strength and analyzing the microstructure at the interface of the joint. The ultrasonic waves improved the wetting in the molten Zn-Al bath by accelerating the removal of bubbles from the interface between alumina and the filler, and this was reflect in improved joint strength.     

The microstructure of ZrO2-Ni-Si3N4 diffusion bonds

In this paper the results are presented of work dealing with the microstructure of ZrO₂-Ni-Si₃N₄ diffusion bonds. Joints were made at 1050°C with bonding times between 22.5 and 360 minutes. The interfacial structure was studied using optical microscopy, scanning electron microscopy and transmission electron microscopy. The element concentrations in the joint were determined by electron probe microanalysis. It was found that at the ZrO₂-Ni interface no reactions take place, whereas at the Si₃N₄-Ni interface decomposition of Si₃N₄ occurs, resulting in a solid solution of Si in Ni and porosity due to the recombination of N to N₂.     

Expression of c-met proto-oncogene product (c-MET) in benign and malignant bone tumors

The expression of c-met proto-oncogene product (c-MET) has been reported to be related to invasive growth or tumor stage in some tumors, but little is known concerning the significance of c-MET expression in bone tumors. With use of formalin-fixed, paraffin-embedded tissue specimens and polyclonal antibody for c-MET, we studied the expression of c-MET in 122 cases of malignant bone tumors (43 osteosarcomas, 24 chondrosarcomas, 21 malignant fibrous histiocytomas of bone, 16 Ewing's sarcoma versus primitive neuroectodermal tumors, 18 chordomas), 65 cases of benign tumors and tumor-like lesions (including 8 giant cell tumors of bone, 8 chondroblastomas, 12 enchondromas, 7 osteochondromas, 10 fibrous dysplasias), 7 cases of articular cartilaginous tissue, and 10 cases of fetal vertebral tissue consisting of foci of enchondral ossification and notochordal tissue. In malignant tumors, c-MET expression was most frequently detected in chordoma (94.4%), followed by chondrosarcoma (54.2%) and osteosarcoma (23.3%). Among the osteosarcoma specimens, c-MET expression was frequently detected in the chondroblastic subtype (66.7%), but the incidence was low in the cases with other subtypes of osteosarcoma. We found no significant correlation between the c-MET expression and the histologic grade of malignancy in either osteosarcoma or chondrosarcoma. c-MET expression was either rarely observed or completely negative in malignant fibrous histiocytomas of bone (4.8%) and primitive neuroectodermal tumors (0%). In benign tumors and tumor-like lesions, c-MET expression was frequently detected in cartilaginous tumors, such as chondroblastoma (62.5%), enchondroma (66.7%), and osteochondroma (71.4%), but no expression was observed in giant cell tumors of bone or any other benign tumors or tumor-like lesions. In normal tissue, c-MET expression was frequently detected in the articular cartilage (100%) and notochord (70.0%) specimens examined. We conclude that c-MET expression as frequent as that observed in the notochordal tissue, chordomas, articular cartilage, and cartilaginous tumors is related to the development of both normal tissue and chondroid tumors.     

Graphitization of carbon beads under pressure

Non-graphitizing carbon beads were heat-treated to 1300°～1900° under 5 kbar. Whereas the original beads carbonized at 1000° graphitize abruptly at 1500° ～ 1600°, the pre-heated ones demand higher temperature for their graphitization. The 1500°-pre-heated and 2100°-pre-heated graphitized above 1700°, and the 2670°-pre-heated above 1900°. In the HTT range where the graphitization occurs, the following changes in texture were observed: after the appearance of cactus-like projections, necks form between beads, needles and tiny flakes appear and optically anisotropic areas grow in size. A remarkable densification was found for the pre-heated beads in the same HTT range.     

Charge disproportionation in CaFeO3 studied with the Mössbauer effect

The Mössbauer effect spectrum of stoichiometric CaFeO₃ at 4 K consisting of two magnetic hyperfine patterns with nearly the same intensities is explained assuming a charge disproportionation 2Fe⁴⁺→Fe³⁺ + Fe⁵⁺. The disproportionation is supposed to set in at or in the vicinity of the Nèel temperature. The single magnetic hyperfine pattern for SrFeO₃ at 4 K, on the other hand, indicates a rapid electron exchange between Fe³⁺ and Fe⁵⁺ ions, for the center shift and the hyperfine field coincide approximately with the average values of the corresponding parameters for CaFeO₃.     

Polymorphic transformation of titanium dioxide by mechanical grinding

The effect of mechanical grinding on the structural transformation of titanium dioxide was studied by using several anatase samples prepared from different starting materials and with various particle sizes. Three anatase samples were prepared by hydrolysis of Ti(O·i-C₃H₇)₄, TiCl₄, and TiOSO₄·2H₂O and one is commercial reagent grade anatase. Each of the as-prepared or heat-treated samples (1.0 g) was ground in a mortar of sintered alumina for up to 96 h in air. The stability of brookite synthesized by grinding was examined by heating in air and under hydrothermal pressure. From the relative amount of the phases estimated by the measurement of the integrated intensity of X-ray line profile and of X-ray crystallite size, DTA and TG, IR spectra, and observation by electron microscope, it is concluded that: 1. the transformation proceeds by a consecutive process from anatase to rutile through brookite by grinding; 2. the smaller the initial particle size of anatase, the more stable the intermediate phase of brookite; 3. the very fine crystals of 520 nm of anatase can be grown to 50150 nm of rutile by grinding for 96 h; 4. the rate process of the transformation depends on the initial particle size and is independent of the difference in starting materials or of surface adsorbants; 5. an appropriate lattice distortion introduced by grinding is considered to stabilize the brookite phase; and 6. the lattice constant and the density of brookite synthesized by grinding,a ₀=0.5447±0.005 nm,b ₀=0.9150±0.0005 nm,c ₀=0.5141±0.0005 nm, andD _x =4.14 g cm^–3 agree with those in natural brookite.