Grain boundary plane reorientation: model experiments on bi- and tricrystals

Experiments on growth and annealing of bi- and tricrystals of an Fe–6at.%Si model alloy are described in this study that investigates the behavior of (a) a free grain boundary in a bicrystal and (b) constrained grain boundaries at the triple junction of a tricrystal. The results clearly show the tendency of the grain boundaries to incline to special orientations dominated mainly by the {011} and {112} planes, thus supporting the idea that the grain boundaries may reorient their planes during annealing and change their character from general to special.     

Early and late results of replacement of the ascending aorta and/or aortic arch using selective cerebral perfusion

From 1987 to 1994, 116 patients received replacement of the ascending and/or aortic arch using selective cerebral perfusion. They were 82 male and 34 female, with average age of 64 years. There were 63 dissecting and 53 true aneurysms. Extent of replacement was: ascending aorta in 13, aortic root in 2, aortic arch in 93, and aortic root and complete arch in 8. Aortic arch replacements were composed of: 29 partial proximal aortic arch replacements, 44 complete aortic arch replacements, and 20 partial distal aortic arch replacements. Nineteen (16.4%) hospital deaths occurred. Univariate testing of pre-, intra-, and post-operative variables followed by stepwise logistic regression analyses identified elderly, ischemic heart disease, postoperative neurologic complication, cardiac dysfunction, renal failure, and massive bleeding as factors having independent association with hospital mortality. Neurologic complication was found in 10 patients (8.6%), and risk factor for this complication was preoperative peripheral vascular disease. Follow-up of hospital survivors documented an overall cumulative 5-year survive rate of 69%. There was no significant difference between dissection and true aneurysms in 5-year survive ratios, which were 63% and 82%, respectively. During follow-up periods, 18 patients died. Half of these cases were vascular deaths, caused by rupture, sudden death and secondary operation. Univariate analyses followed by stepwise Cox testing indicated that chronic obstructive pulmonary disease and a history of postoperative massive bleeding were associated with decreased later survival. Our experience suggests that selective cerebral perfusion is a safe technique for the repair of ascending aorta and/or aortic arch problems. High-risk subgroups of patients with these aortic problems can be identified by risk factors. Aggressive and careful management is necessary for such subgroups to improve early and late survival rates.     

Anemia in patients with colorectal cancer

Although anemia is one of the signs of colorectal cancer, the relationships between histological findings and hematological findings other than hemoglobin level have not been adequately investigated. We investigated the relationship between hematological findings, serum iron, and histological findings in 358 patients (207 men and 157 women) with colorectal cancer. Their mean (+/-SD) ages were 64.3 +/- 12.4 and 63.8 +/- 13.3 years. A hemoglobin level of less than 10 g/dl was the criterion for anemia, and 20.8% of the men and 25.8% of the women met this criterion. Univariate analysis showed that carcinoma of the cecum, ascending colon, and transverse colon; large-size carcinoma, invasion beyond the proper muscle layer; positive lymph node metastasis: and clinical stage (Dukes' B, C, and D) were factors associated with high incidence of anemia. Histological type did not affect the hematological findings. Multivariate analysis showed that age, tumor site, and tumor size were significant factors related to anemia. Depth of invasion, the presence or absence of lymph node metastasis, and Dukes' classification were not significant factors. In the presence of these factors, mean corpuscular volume and mean corpuscular hemoglobin concentration values were low, and red blood cells were microcytic and hypochromic. The incidence of a low serum iron level was about twice the frequency of a hemoglobin level of less than 10 g/dl. The results of the multivariate analysis showed that none of the factors were significantly related to iron deficiency.     

Open distal anastomosis or aortic balloon occlusion technique during complete aortic arch replacement

The technique of open distal anastomosis or application of aortic balloon occlusion catheter designed to occlude the descending thoracic aorta have been used in 33 and 19 patients, respectively, to control bleeding during the procedure of distal anastomosis for complete aortic arch replacement with a prosthetic graft. These two techniques allowed us a simple approach to the lesion and the avoidance of clamp injury to the fragile aortic tissue. Open distal anastomosis was applied for 91% patients of operated aortic dissection and all emergent cases, it's duration ranged from 10 to 110 minutes with an average of 58 minutes under 18.2 degrees C of lowest esophageal temperature. On the other hand, aortic occlusion balloon was inserted for mainly true aortic aneurysm patients without an emergency, and helped to maintain the perfusion pressure on a lower part of body around 50 mmHg by the 1550 ml/min in an average of perfusion flow femoral artery under 21.2 degrees C of temperature. The difference of postoperative renal and liver function evaluated by serum enzyme levels of total bilirubin, GOT, GPT, LDH, creatinine and BUN did not reach to statistical significance between the patients using open distal anastomosis and balloon occlusion, however, the incidence of postoperative complication including either renal, liver dysfunction, abdominal problem or paraplegia was significantly higher in the patient group with open distal technique. Either open distal anastomosis or aortic balloon occlusion technique would be appropriately selected according to the patient's characteristics or the condition of aortic disease to be operated.     

Experimental assessment of endoscopic mucosectomy with a cap-fitted panendoscope

BACKGROUND AND STUDY AIMS: The use of a cap-fitted panendoscope is one method of carrying out endoscopic mucosectomy in the esophagus, stomach, and large intestine. The purpose of this study was to determine the optimal volume of physiological saline for submucosal injection, the rate of mucosal extension after saline injection, the initial size of the resected mucosal specimen, and the most appropriate heights for the fitted caps used in the colon and in the rectum, respectively. METHODS: Endoscopic mucosectomies using cap-fitted panendoscopes were carried out on resected surgical specimens from ten patients with colorectal cancer. RESULTS: It was necessary to inject 12 ml of saline under the mucosa to prevent perforation. Submucosal saline injection extended the mucosa by 1.4 +/- 0.2 times. A cap with a height of 7 mm is suitable for performing mucosectomy in the colon safely, while both 7 mm and 10 mm caps can be used in the rectum. The initial size of the resected mucosal specimens obtained with both caps was 12-20 mm (mean 14 mm) in diameter, with no significant differences. As the sizes of resected mucosal specimens reported in the past have been obtained after submucosal saline injection, it appears that larger specimens can be resected with the cap-fitted panendoscope than with conventional methods. CONCLUSIONS: The conditions under which endoscopic mucosectomy using the cap-fitted panendoscope can be performed safely in the colon and the rectum were suggested by this experimental study using resected specimens. A saline injection of 12 ml under the mucosa is necessary to prevent perforation. A cap with a height of 7 mm is the most suitable size for the colon, while both 7 mm and 10 mm caps can be used in the rectum.     

Method of preventing hepatic artery occlusion during continuous intrahepatic arterial infusion chemotherapy of 5-FU

A randomized clinical trial of combined use of steroids, which have a vascular endothelium-protecting action, was performed to develop a method to prevent hepatic artery occlusion during continuous intrahepatic arterial infusion chemotherapy with 5-FU. The steroid used was dexamethasone palmitate (Limethason), which has a high rate of uptake by endothelial cells. The 24 patients with advanced colorectal cancer were divided into 2 groups randomly and both were treated with 5-FU 250 mg/day by continuous hepatic arterial infusion for three weeks. The weekly dose was 5-FU 7 V (1,750 mg) adjusted to 50 ml with physiological saline in Group A and 5-FU 7 V (1,750 mg) adjusted to 50 ml with Limethason 1 A (4.0 mg of dexamethasone palmitate) in Group B. The reservoir was replaced every week. No changes in the mixture (appearance, pH, granule diameter, dexamethasone palmitate content) were observed up to one week. Hepatic arterial stenosis was observed in 8 cases in Group A (67%), but was not observed in any of the cases in Group B. The above results indicated that Limethason has a preventive effect against hepatic artery occlusion.     

Effect of grain boundary microstructure on fatigue crack propagation in austenitic stainless steel

The effect of grain boundary microstructure on fatigue crack propagation in austenitic stainless steel was investigated in order to control fatigue crack propagation. The fraction of low-Σ coincidence boundaries in specimens was controlled by thermomechanical processing. The specimen with the higher fraction of low-Σ boundaries (73%) showed the lower propagation rate of fatigue crack than the specimen with the lower fraction of low-Σ boundaries (53%). The ratio of intergranular fracture segments to the total crack length was lower for the specimen with the higher fraction of low-Σ boundaries. Moreover, the roles of grain boundaries in the fatigue crack propagation were investigated in connection with grain boundary microstructure, i.e., the character distribution and geometrical configuration of grain boundaries. It is evidenced that the approach to grain boundary engineering is applicable to controlling fatigue crack propagation in austenitic stainless steel.     

Isolation of enterocin SE-K4-encoding plasmid and a high enterocin SE-K4 producing strain of Enterococcus faecalis K-4

Enterococcus faecalis K-4, which produces a class IIa bacteriocin, enterocin SE-K4, carries two plasmids, pEK4S (approximately 60 kb) and pEK4L (approximately 75 kb). Plasmid-curing experiments showed that pEK4S was involved in the production of and immunity to enterocin SE-K4 in strain K-4. A derivative strain, M6, with pEK4S produced a higher amount of enterocin SE-K4 than the parental strain K-4, although its growth rate was lower than that of parental strain K-4. Phenotypic changes in strain M6 are attributed to an increase in plasmid copy number.     

Host egg kairomones essential for egg-larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae)

Several components of an internal kairomone were identified inside eggs of the host,Adoxophyes sp. (Lepidoptere: Tortricidae), that releases egg deposition of the egg-larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae). Pupal hemolymph with the same activity as an internal host egg kairomone was used as a convenient test sample. Heat-treated pupal hemolymph was chromatographed on a Sephadex G-25 column. Each fraction was bioassayed and reacted with ninhydrin. The active fractions were ninhydrin-positive. Each fraction was placed onto an araino acid analyzer, which showed that the amino acids were most abundant in active fractions. Among 22 amino acids, alanine, arginine, glycine, histidine, isoleucine, leucine, methionine, proline, serine, tryptophan, and valine were active. The mixture of these active amino acids was as active as the egg-mass homogenate at the same ratio and concentration, suggesting that the most important component as the kairomone in a host egg is the mixture of several amino acids.     

A new challenge: grain boundary engineering for advanced materials by magnetic field application

This paper gives an overview of “Grain boundary engineering (GBE) for advanced materials by magnetic field application” based on recent experimental work performed on different kinds of structural and functional materials. It is shown that magnetic field application has a great potential and unique advantage as “non-contact processing” for microstructure control, irreplaceable by any other existing processing methods. The control of grain growth and texture by magnetic fields has been found to be generally applicable to many metallic materials, irrespective of whether they are ferromagnetic or not. Grain growth which is controlled by grain boundary migration was found to be strongly affected by magnetic field application. Recent attempts at the grain boundary engineering by magnetic field application through phase transformation have revealed that magnetic phase transformation can provide us a new approach to grain boundary engineering for iron alloys and steels, as well as a new nanocrystalline material produced by magnetic crystallization from the amorphous state. The possibility of engineering applications of enhanced densification using magnetic sintering and magnetic rejuvenation has been discussed for iron powder compacts and deformation-damaged iron alloys, respectively.