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In order to examine the accuracy of the nodal force method, a comparative study of the FEM solution has been performed which includes the edge element and the nodal element formulations. The treatment when the Maxwell stress tensor becomes asymmetric has also been investigated.

The three-field finite element formulation for electromagnetics was proposed as an alternative to the existing vector potential formulations. In the formulation, three fields, that is (i) the vector potential, (ii) the divergence of the vector potential and (iii) a scalar variable which is adjoint to (ii), are interpolated independently and the imposition of the gauge condition can be relaxed. A comparative study of magnetostatic problems is presented which includes the calculations by conventional vector potential formulations using second order nodal elements. It is shown that the three-field formulation gives better results than conventional vector potential formulations with and without gauging.

We have studied the buckling behavior of rectangular bellows under pressure loads. Our final objective is to establish the design guidelines for the rectangular bellows of an experimental fusion reactor, the ITER, the International Thermonuclear Experimental Reactor. Based on the numerical investigation by the FEM, we proposed a simplified method to evaluate the buckling pressure. The evaluation method of the buckling pressure for circular bellows can be found, for example, in the standards of the expansion joint manufacturers association in the U.S.A. (EJMA Standards). For rectangular bellows, however, investigation of the buckling behavior is limited, and EJMA does not provide a method for evaluating the buckling pressure. Therefore, we investigated the buckling behavior of rectangular bellows by the FEM and proposed a simplified evaluation method based on the half-pitch model.

Experimental and theoretical investigations were carried out on heat transfer tubes of an intermediate heat exchanger (IHX). The IHX is a helium;helium heat exchanger of the high-temperature engineering test reactor (HTTR), which is a high-temperature gas-cooled reactor being under construction in Japan. In the IHX, if the secondary gas was lost in an accident, the tubes would be subjected to an external primary gas of 4 MPa at high temperature and the possibility of the creep collapse would occur. Thus, it is indispensable to evaluate the collapse time of the tubes and confirm a calculated method to predict the creep collapse behavior of the tubes under external pressure. Here, the effect of the initial ovality, wall thickness, and pressure level on the collapse time of a heat transfer tube subjected to both constant and cycled external pressure at elevated temperature was examined experimentally and analytically. The creep deformation of the tube obtained by FEM code and the simplified method was a good approximation. The simplified method proposed by Nishiguchi et al. is an effectual method in the estimation of the creep buckling deformation and the collapse time of the tube under external pressure at elevated temperature as compared with themore » experimental results and the FEM. Though many cracks initiated by creep collapse were observed on the outer surface of a few test tubes, the cracks did not pass through the tube thickness, and leak tightness was maintained despite a collapse for all tubes tested.« less

A large deformation theory of deformable solids is proposed in which the loading path dependency and interaction with electromagnetic fields are taken into account. The distinction between the deformed and undeformed configuration is treated rigorously and the problems of stability of structures in electromagnetic fields enter the scope of the theory naturally. As an application of the theory, the governing equations for the quasistatic deformation of ferromagnetic materials under a magnetic field are derived. By employing these linearized equations in the finite element formulation, the stability of quasistatic deformation can be treated generally. >

The effects of the initial ovality, wall thickness and pressure level on the collapse time of a heat transfer tube subjected to external pressure at high temperatures were examined experimentally and analytically. The creep deformation of the tube obtained by the ABAQUS code was a good approximation. The predictions of the creep collapse time were in fairly good agreement with the experimental results. Though many cracks initiated by creep collapse were observed on the outer surface of a few test tubes, the cracks did not pass through the tube thickness and the leak tightness was maintained regardless of a collapse for all tubes tested.

The viscoplasticity theory based on overstress (VBO) is extended to finite deformation (FVBO). Yield surfaces and loading/unloading conditions are not part of this theory which represents creep, relaxation, and rate sensitivity in a “unified” way. Additive decomposition of the rate of deformation into the elastic and the inelastic parts is assumed. For the elastic part, the hypoelastic relation is used. For the inelastic part, the flow law of VBO is augmented by a term quadratic in the overstress together with a modified Jaumann stress rate which jointly or separately allow the modeling of second-order effects.

A one-step time integration method is developed for the finite deformation theory of viscoplasticity based on overstress (FVBO) described in Part I. This time integration method is based on a forward gradient approximation and it leads to explicit expressions of the tangent operators suitable for finite element implementation. Numerical experiments and closed-form solutions for a hypoelastic material in homogeneous deformation states are presented. The FVBO is applied to the modeling of second-order effects in torsion. The numerical results show that a modification of the Jaumann rate and second-order terms of the inelastic rate of deformation are necessary to model the observed effects.

A simplified method is proposed to predict the creep collapse behavior of a long tube subjected to external pressure. The shape of the cross section of a tube is assumed to be quasi-elliptical characterized by a single variable, often called as shape factor in the literature. The growth of the displacement field is represented by the change of shape factor which is governed by an ordinary differential equation. A general class of creep constitutive equations can be employed with an accompanying elasticity whose effect is crucial under higher external pressure. Plane strain condition is assumed. Nonlinearity of stress distribution through the wall of the tube is allowed according to the creep constitutive equation in general, while the strain distribution is assumed to be linear. The method is applied to the analyses of heat tubes, which are typical for heat exchangers of high-temperature gas-cooled reactors, and is compared with the computer solution by the finite element method based on a finite deformation theory, as well as solutions by other simplified methods.

A large deformation theory of deformable solids has been proposed by the authors. In this theory, the loading path dependency and interaction with electromagnetic fields are taken into account and the distinction between the deformed and undeformed configurations is treated rigorously. In this paper, the governing equations for electromagnetism are summarized and the expressions by differential forms are given. The relationships with other theories which deal with moving rigid bodies and/or deformable bodies are also discussed

X-ray CT images of the head obtained from thirteen patients (9 men and 4 women) among 33 patients (19 men and 14 women) with nasal non-Hodgkin's lymphoma (NHL) who had been seen at Kitasato University Hospital during the period from April 1975 to March 1995 were retrospectively reviewed to search for useful prognostic image factors for nasal NHL. Extracavitary subcutaneous tumor extension into the nasal wing or cheek, and tumor penetration through the nasal septum revealed on X-ray CT images seemed to be likely indicators of a poor prognosis for patients with nasal NHL.

We analyzed 119 patients with cervical carcinoma treated by postoperative radiotherapy from 1983 to 1993. Five- and 10-year survival rates of all patients were 77% and 67%, respectively. The 10-year survival rates for stage I (54 patients) and stage II (65 patients) were 76% and 58%, respectively. Ten-year survival rate for patients with both deep stromal invasion and lymph node metastasis was 37% which was much lower than in those without them (more than 90 %), indicating that they seemed to be factors related to poor prognosis. The results of multivariate analysis showed that the number of metastatic lymph nodes was the most important prognostic factor. Leg edema and intestinal and urinary insufficiency as late complications of postoperative radiotherapy occurred at low incidences and were well tolerated.

This study was performed to compare our nonclonogenic survival assay (densitometry assay, DM assay) with the widely used clonogenic assay. The established cell lines (HeLa, RMUG, IMR, GOTO) were grown in F 10 medium. The cells were spread in 24-well plates, irradiated with different doses, cultured for about one week and stained with crystal violet after the culture period. Taking the transparent images of the stained well on the light source with the CCD camera, the images were collected with the matrix size 64 x 64, and the integrated optical density of the entire surface of each well was determined by computer with our original program. As the number of cells in the well is reflected by its staining density, the surviving fraction was calculated as the fraction of growth in the irradiated wells relative to controls. The survival curves obtained by the densitometry method showed good correlations with those obtained by clonogenic assay. It is possible to predict intrinsic radiosensitivity with this assay, even if the cells do not form good colonies. However, this method is based on measurements in cultures which depend on the metabolism and growth kinetics of the irradiated cells. Cells should grow exponentially in the same manner in any well to obtain a result similar to that of clonogenic assay, although growth kinetics may be altered by irradiation. Thus, the endpoint must be strictly standardized.

This study was performed to determine the biological effect of carbon beams on mammalian cells (HeLa, RMUG), in comparison with 200 KVp X-rays. Carbon beams were generated by the Riken Ring Cyclotron. An increase in the relative biological effect (RBE) was observed in both cell lines as the LET of the carbon beam increased between 20 and 80 keV/microns. The RBE depended on the size of the irradiation dose at the higher LET region, and increasing the dose from 0.8 Gy to 3.2 Gy decreased the RBE from 2.9 to 2.7. The survival curves of cells irradiated with 20 keV/microns carbon beams showed an initial shoulder. When RMUG was irradiated at 4 Gy with 200 KVp X-rays, the recovery rate between two split doses (6 hour interval) was 1.7. RMUG irradiated with 20 keV/microns carbon beams (4 Gy) showed a recovery rate of 1.4. Recovery between split dose irradiation was observed with both X-ray and carbon beam irradiation; however, the recovery rate was lower with carbon beams. Cells irradiated with LET higher than 40 keV/microns did not show recovery between split doses.

This study was carried out to determine the effect of irradiation of a tumor on the development of lung metastases. SANH, a spontaneous sarcoma, was isotransplanted in the right thighs of C3H mice which were either locally preirradiated (30 Gy: TBR) or non-irradiated. When the tumors had grown to 7 mm in diameter, they received 20-30 Gy of electron beams (RTx). The tumor-bearing legs were amputated at various tumor sizes, and the incidence of metastasis and number of lung nodules were compared in each treatment group. The incidences of metastases from 7 mm tumors in mice with regrowing tumors after RTx (30 Gy) and non-irradiated mice were 28% and 4%, respectively. When tumors grown in preirradiated legs were removed at 7 mm in diameter, the incidence of metastases (58%) was also enhanced by preirradiation of the tumor bed. Seven millimeter tumors that were growing in TBR legs and received RTx (20 Gy) developed a higher incidence (82%) and greater numbers of metastases than either the RTx or TBR groups. To determine the relationship between the interval of tumor bearing and development of metastases, tumors were removed at various intervals after tumor transplantation in 4 groups, namely, non-irradiated, TBR, RTx and TBR with 20 GyRTx. Lung metastases came later but increased steeply in mice given either TBR or RTx, compared with non-irradiated mice. Tumors growing in TBR and receiving RTx (20 Gy) developed many more metastases than any other group.(ABSTRACT TRUNCATED AT 250 WORDS)

Forty-five patients with retinoblastoma were treated at Keio University Hospital from 1970 to 1990. Thirty-two patients had unilateral lesions and 13 had bilateral lesions. Twenty-nine patients with unilateral and 12 with bilateral lesions underwent enucleation for advanced tumor. As a result, 3 patients with unilateral retinoblastoma and all patients with bilateral disease were treated with radiotherapy (40-50 Gy) combined with or without cryotherapy and/or photocoagulation. One patient with unilateral lesion treated with radiotherapy and chemotherapy had metastases at the first visit to our clinic and was excluded from this analysis. Among 16 eyes (15 patients) treated with radiotherapy, 6 eyes had recurrence and needed retreatment. Cataract occurred in 6 of 12 eyes and good vision was preserved in 5 of 10 eyes in which function could be evaluated.

In a previous study (Furuta, Y., Hunter, N., Barkley, H. T., Jr., Hall, E., and Milas, L., Cancer Res., 48:3008-3013, 1988), we demonstrated that inhibition of prostaglandins in murine tumors by indomethacin results in the augmentation of tumor response to single doses of ionizing radiation. The results of the present study show that indomethacin augmented tumor response to fractionated irradiation as well, the enhancement factor being more than 2. The effect of indomethacin on tumor growth and on tumor radioresponse was assayed in normal mice, mice deficient in T-cells (nude mice), and mice whose general immunocompetence was suppressed by whole-body irradiation. The antitumor activity of indomethacin was not significantly influenced by the immunocompetence of the tumor host. Since indomethacin inhibited tumor neoangiogenesis, we postulated that this inhibition is a major mechanism responsible for the antitumor activity of indomethacin. In contrast, potentiation of tumor radioresponse by indomethacin was greatly dependent on immunocompetence of tumor host: it was significantly reduced, or even abolished, when tumor grew in nude and whole-body irradiation mice. Thus, while immunocompetence of the tumor host has no significant effect on antitumor action by indomethacin, it plays a decisive role in the potentiation of tumor radioresponse by indomethacin.

Various singularity finite elements proposed so far are reviewed and their correlations are discussed. The method adopted in the comparative study is based on the singularity mapping or transformation technique. It is suggested that a compact design of computational routines is materialized by using the element which embodies singularity transformation and can be compatible with the notion of using the variable-number-nodes element in the general-purpose computer programs.

General parametric elements adopt different functions for the expression of unknown field variables and the mapping of geometric configurations. By introducing the concept, paper shows that useful singularity and infinite elements can be produced in a unified manner. In the derivation of these especial elements, a technique is incorporated for imposing respective constraint conditions in the analysis. In the second part of paper, the technique is generalized so that a variety of constraint conditions are implemented in the standard finite element analysis routine at the level of element stiffness formations. It is pointed out that the joint or interface element is also an interesting application of the proposed method.

Three kinds of t-butyl per (trans-2-substituted cyclopropyl) acetates (RH, CH3, C6H5) were synthesized from the corresponding acyl chlorides and thermally decomposed in cyclohexane to investigate the chemical stability and behaviour of the cyclopropylcarbinyl radical. Clean first-order kinetics were obtained in all of the thermal decomposition reactions. The experimental fact that the decompositoin rates and activation parameters of these three t-butyl peresters are similar to each other may indicate the absence of the ionic character in the transition state suggesting the almost complete homolytic decomposition of these peresters. Although the typical concerted decomposition might be invalid for these peresters in view of the activation parameters, it would be suggested from the product studies that the decomposition of these peresters was characterized by a considerable loss of their acyl-alky] bonds at the time of the fission of their OO bonds. The products yielded from the thermal decomposition of t-butyl per (trans-2-phenylcyclopropyl) acetate in various hydrogen donating solvents consisted of three hydrocarbons and two t-butyl ethers. The formation of these t-butyl ethers, possibly cage products, was significant.

Homolytic aromatic substitution and hydrogen abstraction reactions with cyclopropyl radical were carried out to determine the reactivity and ionic character of cyclopropyl radical by examination of the orientation effect, partial rate factor and influence of substituents. By thermal decomposition of biscyclopropaneformyl peroxide in a series of substituted benzenes, the corresponding cyclopropylated benzene derivatives (the mixture of ortho, meta and para isomers) were obtained in moderate yield. In view of the orientation effect and the partial rate factor, the cyclopropyl radical seems to be fairly free from polar effect, and to resemble the phenyl radical more than the common alkyl radical although the cyclopropyl radical has a slightly higher reactivity than the phenyl radical. The relative reactivity of the 2-phenylcyclopropyl radical in the hydrogen abstraction reaction toward the benzylic position of ring-substituted toluenes gave good Hammett's correlation with the slope of + 0·20 suggesting little ionic character in the transition state. This result was in good agreement with the conclusion obtained from homolytic aromatic substitution reaction and with the chemical reactivity to be expected from the non-planar nearly sp 2 -hybridized conformation of the cyclopropyl radical.

Bei der im Titel erwahnten Reaktion entstehen β-Hydroxynitrile (IV), (VI) und (VIII), und β-Hydroxycarbonsaureester (X).

Though the mechanism of 201Tl accumulation in thyroid tumours is not known yet, there are some hypotheses. In order to study the mechanism, potassium contents and Na, K-ATPase, of various organs of rats and human thyroid glands were analyzed . The conclusion through these experiments is as follows, 1 as the potassium contents and Na, K-ATPase activity of thyroid glands are not obviously higher than those of other organs, the 201Tl accumulation in thyroid is thought to be not owing to the similarity to the potassium ion, 2 pointing out high activity of Na, K-ATPase in heart and kidney, the accumulation mechanism of 201Tl in these organs has high relation to this activity, 3 though there is a tendency to have higher potassium contents among thyroid tumours, the difference in potassium contents between their histopathology is small; so that the tumour specificity is not explained from the potassium contents, and 4 as for Na, K-ATPase activity of thyroid tumours, papillary adenocarcinoma and follicular adenoma, which take more in 201Tl, have tendency to show higher activity; adenomatous goitre, which take less in 201Tl, has tendency to show lower activity. We suggested that the factor relating to the accumulation mechanism of 201Tl may be multiple, and Na, K-ATPase plays an important role in 201Tl specific uptake in thyroid tumours.

The antitumor activity of direct current was studied in mice which were transplanted fibrosarcoma (FSa) into the right thigh. Mice were inserted electrodes into tumor and normal tissue surrounding the tumor, and treated with constant current. The direct current therapy (D.C.T.) (0.6 mA, 120 min) alone was effective to regress tumor, but tumor was not eradicated by D.C.T. alone. Cyclophosphamide (CPA, 100 mg/kg) could markedly reduce the FSa tumor size, but all tumor regrew finally. When D.C.T. was combined with CPA (100 mg/kg), the therapeutic response of FSa tumor was enhanced in mice which were inserted cathode into tumor. For example, in mice receiving direct current (0.6 mA, 120 minutes), the cure rate was 70% compared with 30% by the anode in tumor. Using cure rate assay, D.C.T. and about half dose of CPA could give the similar treatment results as the full dose of CPA alone. That is, D.C.T. will be able to reduce the dose of chemotherapeutic agents. Combination of D.C.T. and doxorubicin was not so effective as CPA, but showed the similar results. The experimental results suggest that D.C.T. alters the drug distribution in the tumor and makes the drugs more effective.