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To improve the fatigue properties in the welded joints of high strength steels, we developed an elongated bead method for low transformation temperature (LTT) welding materials. The proposed method intensifies the compressive residual stress and reduces the stress concentration. We investigated the length of the elongated bead in the boxing fillet portion of the gusset front, the effectiveness of inexpensive LTT wires with low Ni content and the potential applicability to repair welding. The most effective welding method, overlay of the elongated bead LTT weld metal on the conventional boxing fillet weld metal, extended the fatigue lifetime of the boxing fillet by seven to ten times. Residual stress distributions in joints welded with low-Ni metals of different martensite start temperatures (Ms) as well as the stress concentration in weld joints formed from elongated beads with different lengths were investigated in finite element simulations. Residual stress of weld and its toe was decreasing as the Ms of weld metal was lowering and the most compressive residual stress was obtained for weld metal with Ms temperature of 184 °C. The stress concentration reduces by about 30% of fatigue load, and the residual stress decreases down to compressive one of −685 MPa for the LTT overlay welding elongated bead treatment.

In this study, by conducting the creep–fatigue crack growth tests using circular notched round bar specimens for Alloy 617, the crack growth behaviour was characterized on the basis of crack growth data obtained from the direct current potential drop DCPD method, which results in the assurance of the high accuracy of crack length measurement. Furthermore, on the basis of catastrophe theory, an attempt is made to predict theoretically the threshold temperature of creep crack growth related to the diffusion creep mechanism.

The W-added 12Cr ferritic heat resistant steel has been developed as a turbine rotor material which is used under high temperature creep-fatigue conditions. In this study, crack growth tests using CT specimen under the creep-fatigue interaction conditions were conducted under various conditions of stress holding time, applied stress and temperatures. As a result, the effect of load frequency on crack growth behaviour and its life for this steel was characterised by the three-dimensional curved surface based on the concept of non-equilibrium science. Furthermore, a predictive law of crack growth life under the creep-fatigue interaction conditions was derived based on the concept of Q with the transition function of crack growth life from fatigue to creep.

The immune response is altered according to hormonal and metabolic status. Obesity increases the inflammatory and fever response, whereas loss of gonadal steroid decreases behavioral response to immune stress. However, the immune systems of ovariectomized animals exhibiting obesity and gonadal steroid deficiency, particularly under septic conditions, have not been fully examined. In the present study, we evaluated the ovariectomy-induced changes of central and peripheral immune responses to life-threatening septic stimulus. Ovariectomized rats showed heavier body weight and lighter uterine weight when compared with gonadally intact rats. Fever response to septic dose of lipopolysaccharide (LPS) in ovariectomized rats was less evident when compared with that in gonadally intact rats. In addition, under LPS-injected septic conditions, hypothalamic gene levels of Interleukin-1β (IL-1β), Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and serum protein levels of IL-1β and TNF-α in ovariectomized rats were lower than those in gonadally intact rats. On the other hand, IL-6 levels in visceral fat under septic conditions were higher in ovariectomized rats than in gonadally intact rats. These findings indicate that ovariectomy-induced site-specific changes in cytokine response under septic conditions. As hypothalamic, but not peripheral, pro-inflammatory cytokines are directly involved in the fever response, the attenuation of fever response observed in ovariectomized rats may be caused by a reduction in central cytokine responses.

In this study, to clarify the behaviour of micro- and macro-creep damage progression for P92 under multiaxial stress field, interrupted creep tests, analysis of multiaxial stress and detailed the cross-sectional observations were conducted on a circular notched round bar specimen which produces the multiaxial stress field due to the plastic constraint. As a result, creep voids were initiated at the early stage and they were formed up to the final fracture. These phenomena were found to be detected using direct current potential drop (DCPD) method. These results concern the development of the measurement of creep crack initiation. The distribution of high void area fraction was in good agreement with that of high hydrostatic stress and high multiaxial stress. This result indicates that multiaxial stress affects the void formation. Furthermore, the micro-creep damage of each interrupted specimen was evaluated by using the electron backscatter diffraction (EBSD) method which can analyse crystallographic misorientation caused by creep strain. The results of EBSD analyses indicated that the value of grain reference orientation deviation (GROD) closely concerns the void initiation.

In order to detect creep–fatigue damage before the crack initiation stage, an investigation into damage behaviour based on the electron backscattered diffraction (EBSD) method for a polycrystalline nickel base superalloy has been carried out. The average misorientation within grains increases linearly up to the initiation of cracks with the increase in creep strains. Even if stress distributions exist by stress concentration, assessment in all the damage areas allowed the evaluation of creep damage regardless of geometrical influence. Furthermore, the influence of strain rates, introducing fatigue and testing temperatures are hardly observed in the misorientation analysis. Misorientation almost corresponded to inelastic strain regardless of those influences. Quite a small misorientation caused by fatigue led to an equivalent result between creep conditions and creep–fatigue conditions. It is concluded that the misorientation analysis of damaged materials based on the EBSD method allows the quantitative estimation of creep strain and the assessment of remaining creep fracture life.

Objective:High-molecular weight (HMW) isoform level and HMW ratio have been shown to be better predictors of insulin sensitivity and metabolic syndrome than total adiponectin level. We examined the changes in circulating levels of HMW adiponectin and ratios of HMW to total adiponectin in women during the menopausal transition. Methods:We conducted a cross-sectional study in 217 healthy women and divided them into 4 stages: 58 women in pre-menopausal, 69 women in perimenopausal, 62 women in early post-menopausal and 28 women in late post-menopausal phase. Serum levels of total adiponectin and HMW adiponectin were measured by an enzyme-linked immunosorbent assay. Results:In late post-menopausal women, HMW adiponectin level was significantly higher than that in peri-menopausal women and the HMW to total adiponectin ratio was significantly lower than that in early post-menopausal women. In peri-menopausal women, HMW adiponectin level was significantly lower than that in pre-menopausal women and HMW to total adiponectin ratio was significantly lower than the ratios in pre-menopausal and early post-menopausal women. Conclusion:The ratio of HMW to total adiponectin is low in late post-menopausal women, though both levels of total and HMW adiponectin were high after menopause in our cross-sectional study.

The relationship between lipid profiles and Alzheimer disease (AD) pathology at the population level is unclear. We searched for evidence of AD-related pathologic risk of abnormal lipid metabolism.

We examined the association between diabetes-related factors and pathology of Alzheimer disease (AD) to evaluate how diabetes affects the pathogenic process of AD.

Kisspeptin and its corresponding receptor, the G protein-coupled receptor 54, play an important role in reproductive systems. It has been suggested that reproductive disorders in metabolically disrupted animals are caused by the alteration of hypothalamic KiSS-1 systems. Immune/inflammatory challenge is also known to disrupt reproductive function. However, the effects of immune/inflammatory challenge on KiSS-1 systems have not been investigated. In this study, we showed that lipopolysaccharide (LPS) injection decreased hypothalamic KiSS-1 mRNA expression as well as plasma LH levels in ovariectomized rats. Indomethacin completely blocked the suppressive effects of LPS on LH secretion and KiSS-1 mRNA level. Furthermore, we showed that iv injection of kisspeptin increased plasma LH levels in LPS-administrated rats to the same degree as in saline-injected rats. These results suggest that KiSS-1 systems are sensitive to immune/inflammatory challenge conditions and transmit these signals into the central reproductive system.

Crystallization kinetics and texture evolution in iron-based amorphous alloys (Fe78Si9B13, Fe73.5Si13.5B9Nb3Cu1) under a magnetic field have been studied. We have found that the application of a magnetic field during crystallization at a temperature ranging the Curie point of the amorphous phase and that of the crystalline bcc-Fe(Si) phase can produce a {110} texture in the alloys. X-ray diffraction with the Schulz method revealed that {110} oriented grains were preferentially nucleated due to the magnetic field. The studies of crystallization kinetics found that the nucleation rate of the α-Fe(Si) phase in amorphous Fe73.5Si13.5B9Nb3Cu1 was enhanced approximately three times as high with the 6T magnetic field than without field. The volume fraction of crystalline α-Fe(Si) phase produced was increased by the magnetic field.

Activin type II receptors (ActRIIs) including ActRIIA and ActRIIB are serine/threonine kinase receptors that form complexes with type I receptors to transmit intracellular signaling of activins, nodal, myostatin and a subset of bone morphogenetic proteins. ActRIIs are unique among serine/threonine kinase receptors in that they associate with proteins having PSD-95, Discs large and ZO-1 (PDZ) domains. In our previous studies, we reported specific interactions of ActRIIs with two independent PDZ proteins named activin receptor-interacting proteins 1 and 2 (ARIP1 and ARIP2). Overexpression of both ARIP1 and ARIP2 reduce activin-induced transcription. Here, we report the isolation of two isoforms of ARIP2 named ARIP2b and 2c. ARIP2, ARIP2b and ARIP2c recognize COOH-terminal residues of ActRIIA that match a PDZ-binding consensus motif. ARIP2 and its isoforms have one PDZ domain in the NH2-terminal region, and interact with ActRIIA. Although PDZ domains containing GLGF motifs of ARIP2b and 2c are identical to that of ARIP2, their COOH-terminal sequences differ from that of ARIP2. Interestingly, unlike ARIP2, overexpression of ARIP2b or 2c did not affect ActRIIA internalization. ARIP2b/2c inhibit inhibitory actions of ARIP2 on activin signaling. ARIP2 is widely distributed in mouse tissues. ARIP2b/2c is expressed in more restricted tissues such as heart, brain, kidneys and liver. Our results indicate that although both ARIP2 and ARIP2b/2c interact with activin receptors, they regulate ActRIIA function in a different manner.

It was shown that external magnetic field of 5 kOe slows down the kinetics of grain boundary grooving in iron at 750 °C by about one order of magnitude. This observation is discussed in terms of magnetic effect in surface diffusion.

Activin has previously been shown to act as a nerve cell survival factor and to have neurotrophic effects on neurons. However, the role of activin in regulating neurotransmitter expression in the central nervous system and the exact mechanisms involved in this process are poorly understood. In the present study, we report that activin A and basic fibroblast growth factor (bFGF) synergistically increased the protein level of tyrosine hydroxylase (TH), and also greatly increased the TH mRNA level, in both mouse E14 striatal primary cell cultures and the hippocampal neuronal cell line HT22. Activin A and bFGF cooperatively stimulated nuclear translocation of Smad3 and specifically activated ERK1/2, but not p38 or JNK. Interestingly, a specific inhibitor for MEK, U0126, efficiently blocked the induction of TH promoter activity by activin A and bFGF, indicating that activin A collaborated with bFGF signaling to induce the TH gene through selective activation of ERK-type MAP kinase in mouse striatal and HT22 cells. These data suggest that activin A may act in concert with bFGF for the development of TH-positive neurons.

Despite the high antitumor activity of camptothecins, few derivatives have been developed and tested for human treatment of solid tumors, due to unpredictable toxicity mainly connected to their poor water solubility. We report the conjugation of the antitumor agent 10-amino-7-hydroxy camptothecin (SN-392) to linear or branched poly(ethylene glycol)s (PEGs) of different loading capacity through a tri- or tetrapeptide spacer selectively cleaved by lysosomal enzymes (cathepsins). A synthetic strategy based on the chemoselective acylation of the aromatic amino group in the presence of the unprotected C20 tertiary alcohol allowed high overall yields. Two conjugates demonstrated good stability at physiological pH and in mouse plasma (nonspecific proteases) but slowly released the drug payload in the presence of the lysosomal enzyme cathepsin B1. Compound 3, selected for in vivo experiments, was very active against P388, P388/ADM leukaemia, and Meth A fibrosarcoma cell lines, scoring T/C% values comparable with the camptothecin derivative CPT-11. Pharmacokinetic studies indicated that 3 acts as a reservoir of 10-amino-7-ethylcamptothecin, as the mean residence time (MRT) is about 3-fold higher than that of the free drug.

The venom obtained from Okinawan box-jellyfish (Habu-kurage), Chiropsalmus quadrigatus, produced increases in contractions of isolated rat right atrial preparations in a concentration-dependent manner without changes in a spontaneous beating rate. These increases in contractions were significantly inhibited by diltiazem and did not show tachyphylaxis. The venom also produced increases in contractions of isolated rat aortic ring preparations (endothelium-intact) in a concentration-dependent fashion, which were reproducible with repeated application and were significantly inhibited by diltiazem or heating. These increases in vascular contractions were weakened in endothelium-denuded preparations, and almost abolished in a calcium-free medium. On the other hand, the venom at higher concentrations diminished contractions of both myocardial and vascular preparations and did not show reproducibility. These results suggest that the Habu-kurage venom is heat-labile and may increase contractions of cardiac muscle and aortic smooth muscle by increasing calcium influx into muscle cells, and that the venom at higher concentrations may produce dysfunction of muscle contractile systems due to calcium overload.

Pregnancy and lactation induce dynamic changes in maternal bone and calcium metabolism. A novel cytokine termed osteoprotegerin (OPG)/osteoclastogenesis-inhibitory factor (OCIF) was recently isolated; this cytokine inhibits osteoclast maturation. To define the effects of pregnancy and lactation on circulating OPG/OCIF in mothers, we studied the changes in the levels of OPG/ OCIF as well as those of calcium-regulating hormones and biochemical markers of bone turnover in the maternal circulation during pregnancy (at 8-11 weeks, at 22-30 weeks, at 35-36 weeks and immediately before delivery) and lactation (at 4 days and at 1 month postpartum). Serum intact parathyroid hormone levels did not change and were almost within the normal range in this period. In contrast, serum 1,25-dihydroxyvitamin D levels increased with gestational age and were above the normal range during pregnancy. After delivery, they fell rapidly and significantly (P<0.01) to the normal range. The levels of serum bone-specific alkaline phosphatase, one of the markers of bone formation, increased with gestational age. After delivery, these levels were further increased at 1 month postpartum. The levels at 1 month postpartum were significantly higher than those at 8-11 and 22-30 weeks of pregnancy (P<0.01 and P<0.05 respectively). The levels of serum C-terminal telopeptides of type I collagen, one of the markers of bone resorption, did not change during pregnancy. After delivery, they rapidly and significantly (P<0.01) rose at 4 days postpartum, and had then fallen by 1 month postpartum. Circulating OPG/OCIF levels gradually increased with gestational age and significantly (P<0.01) increased immediately before delivery to 1.40+/-0.53 ng/ml (means+/-S.D.) compared with those in the non-pregnant, non-lactating controls (0.58+/-0.11 ng/ml). After delivery, they fell rapidly to 0.87+/-0.27 ng/ml at 4 days postpartum and had fallen further by 1 month postpartum. These results suggest that the fall in OPG/OCIF levels may be partially connected with the marked acceleration of bone resorption after delivery.

ABSTRACTAn in-situ tritium-deuterium gas-purification system has been constructed to produce a high-purity D-T target gas for muon catalyzed fusion experiments at the RIKEN-RAL Muon Facility. At the experiment site, the system enables us to purify the D-T target gas by removing 3He component, to adjust the D/T gas mixing ratio and to measure the hydrogen isotope components. The system is specially designed to handle the D-T gas with a negative pressure, and the maximum tritium inventory of 56 TBq (1500 Ci) is operated. The employed combination of a palladium filter and a cryotrap has demonstrated as an efficient device to purify hydrogen gas with a negative pressure. We have completed a series of muon catalyzed d-t fusion experiments at various tritium concentrations, including an experiment with a non-equilibrium D2-T2target condition. The muon catalyzed t-t fusion process has also been studied using the tritium gas supplied free of 3He by the system.

ABSTRACTJAERI has been developing an improved compact tritium gas enrichment/recycling system to handle relatively smaller amount of tritium for efficient researches on tritium processing and development work. An electrochemical hydrogen pump based on CaZr0.9In0.1O3− αproton conductor is investigated to separate hydrogen isotopes directly from inert gas carrier after the enrichment process of the system. The prototype hydrogen pump was developed for the first time to operate under vacuum condition at the cathode compartment, and the performance test was carried out.

OBJECTIVE: Leptin is an adipocyte-derived hormone, which is the product of the obese gene and it is thought to play important roles in pubertal development and maintenance of reproductive function in the female. In a study using adult male or female rats, it was found that leptin stimulated the secretion of gonadotropin directly from the pituitary in a dose-related manner. However, there is no study in juvenile female rats before puberty. METHODS: In this study, we cultured pituitary cells from 4-, 6- and 8-week-old female Wistar rats with leptin (0-10(-7)mol/l) and gonadotropin-releasing hormone (GnRH) (0 or 10(-8) mol/l). Basal or GnRH-stimulated secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and their synthesis within cells were determined by radioimmunoassay (RIA). RESULTS: Leptin induced bell-shaped dose--response curves of basal LH and FSH secretion from cultured cells of every age-group of rats studied. The most effective concentration of leptin on the basal secretion of LH and FSH from 6- and 8-week-old cultured pituitary cells was 10(-10) mol/l. This leptin concentration was consistent with circulating physiological serum leptin levels at each age. As for juvenile 4-week-old pituitary cells, the most effective concentration was 10(-11) mol/l which was lower than that of 6- and 8-week-old rats. It was consistent with the circulating serum leptin levels of 4-week-old rats. Also, the synthesis and the GnRH-stimulated secretion of LH and FSH were effectively controlled by leptin at concentrations similar to the serum leptin levels of given ages. CONCLUSIONS: Leptin induced pituitary cells to synthesize and secrete both LH and FSH regardless of the presence or absence of GnRH. The concentration of leptin that induced the greatest synthesis and secretion of gonadotropins from pituitary cells changed around the pubertal period. The most effective leptin concentrations in each experiment were similar to the physiological serum leptin level at each animal age. These results indicate that leptin stimulates gonadotrophs not only in the pubertal and the mature period but also in the juvenile period before puberty. It is also conceivable that leptin may modulate the sensitivity of gonadotrophs until the appearance of GnRH stimulation, and may be the factor that brings about puberty onset.

Abstract:: X-ray spectroscopy of muonic atoms is an important tool to obtain information on the nuclear charge distribution of nuclei. It has been successfully used for many years to study stable isotopes in condensed or gaseous states. A new method has been proposed to extend muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable nuclei. This new method allows studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility study at RIKEN-RAL muon facility is also reported.

The lifetime of the positive muon (τμ+) can be directly associated with the Fermi Coupling Constant (GF), which is one of the most basic parameters of the Standard Model. However, the current experimental accuracy of the τμ+is ∼30 ppm and it has not been improved for more than 15 years. We propose a new experiment for a pulsed muon facility such as RIKEN-RAL to measure the muon lifetime with multi-decay per one time window method. The advantage of our setup, no time window limitation, enables us to test the exponential decay law (EDL) in the long decay time region at the same time. The preliminary analysis set a new upperlimit for the EDL deviation in the muon decay. We accumulated ∼1010muon decays and analysis is in progress.

We are involved in a program aimed at a first-principles examination of the possibility of helium bubble formation in solid hydrogen. Our procedure is based on an extension of the Hartree–Fock cluster approach that we have been using for study of individual He+ions in solid hydrogen. The preliminary results of our cluster investigations of a particular configuration of two He+ions in neighboring tetrahedral interstitial positions are presented here. It has been found that the hydrogen molecules common to the two He+ions lead to a substantial attractive force between the ions that almost overcomes their inherent repulsion, leading to a binding energy for this configuration only slightly less than the binding energy for two well separated trapped He+ions. The analysis of our results have suggested future investigations of different pairs of trapping sites which appear to be more favorable for providing higher binding energies for the He+pairs.

We report a major upgrading work currently underway at the RIKEN-RAL Muon Facility. A slow muon beam line has been constructed at Port 3 experimental area in order to generate a low-energy, low-emittance positive muon beam, which will open many new possibilities for use of the muon beam. Meanwhile, a new experimental port is under construction to accommodate new experimental programs such as measurement of muonic X-rays from ions implanted to deuterium layer.

The muon science facility is one of the experimental arenas of the JKJ project, which was recently approved for construction in a period from 2001 to 2006, as well as neutron science, particle and nuclear physics, neutrino physics and nuclear transmutation science. The muon science experimental area is planned to be located in the integrated building of the facility for the materials and life science study. One muon target will be installed upstream of the neutron target in a period of phase 1. The beam line and facility are designed to allow the later installation of a 2nd muon target in a more upstream location. The detailed design for electricity, cooling water, primary proton beam line, one muon target and secondary beam lines (a superconducting solenoid decay muon channel, a dedicated surface muon channel, and an ultra slow muon channel) is underway. In the symposium, a latest status of the muon science facility at JKJ project will be reported.

We have measured X-rays and neutrons associated with the muon catalyzed t–t fusion process at the RIKEN-RAL Muon facility. In the X-ray measurement, we observed Kαand KβX-rays originating from the muon sticking process in muon catalyzed t–t fusion, and obtained the KαX-ray yield and the Kβ/Kαintensity ratio. An average recoil energy of the (μ−α) atoms in a solid T2medium was determined from the observed Doppler broadening width of the KαX-ray line. The obtained t–t fusion neutron has shown an exponential time spectrum with a single component and a continuous energy spectrum with a maximum energy of 9 MeV. We have determined the t–t fusion neutron yield, the t–t fusion cycling rate and the muon sticking probability from the neutron data. The obtained maximum neutron energy is a very peculiar value from the view point of the reaction Qvalue (11.33 MeV) with the three-particle decay mode at the exit channel: t+ t→ α + n+ n+ Q. The obtained neutron energy distribution was analyzed by a simple model with two neutron energy components; reasonable agreement has been obtained, suggesting a strong (n–α) correlation in the exit channel of the t–t muon catalyzed fusion reaction.

We observed the dependence of the rate of the muon-catalyzed fusion (μCF) on the ortho–para state (the nuclear spin state) of deuterium in order to investigate the source of the surprising contradiction of the resonant formation rate of a ddμ molecule in solid between experiments and theories. The ortho–para dependence of the molecular formation rate and the dμ hyperfine transition rate was clearly observed for the first time. The rate of the hyperfine transition by scattering was determined and was smaller than that of the theoretical prediction. The back decay rate was experimentally determined for the first time. Also, new insight for phenomena of the dd–μCF in solid was presented by interpreting the observed ortho–para dependence.

JAERI has been developing an improved compact tritium gas enrichment/recycling system for efficient research and development work using tritium. A proton conductor has been investigated and a compact enrichment system was designed with a hydrogen pump employing a proton conductor. The pump can separate hydrogen directly from the helium gas carrier and minimize the size of the system. A prototype hydrogen pump was developed and its performance test was started.

A systematic study on muon catalyzed fusion (μCF) was conducted in solid deuterium and tritium (D–T) mixture. A variety of experimental conditions were investigated, i.e., tritium concentrations from 20 to 70%, temperatures from 5 to 16 K. A preliminary analysis result suggests a steep decrease in the dtμ-molecule formation rate with decreasing temperature, and also an increase in the probability for a muon reactivation after an α-sticking phenomenon.

We report on the latest development of a new method for extending muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable nuclei. This would allow studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility study at RIKEN-RAL muon facility is also reported.

We are currently investigating the influence of vibrational effects on the strength of trapping of He+in solid hydrogen. Such effects can lead to an isotope dependence of the trapping energy associated with the hydrogen molecules and He+ion. At the present time, our focus is on the isotope effect for 3He+and 4He+, which we are studying through the vibrational motions of the trapped He+ions in the potential they experience as they move about their equilibrium positions. The potential governing the vibrations has been obtained from Hartree–Fock cluster calculations of the total energy of the cluster composed of the He+ion and up to the third nearest neighbor hydrogen molecules as a function of the displacement of the He+ion from its trapped position. The energy eigenvalues for the ground vibrational states of 3He+and 4He+in this potential come out as 1.29 and 0.96 meV, respectively, leading to corresponding reductions by these amounts in the binding energy of 8.6 eV for both ions without vibrational effects. The difference of these reductions can be considered as an isotope shift, its value for this case being 0.33 meV. From the analysis for these results, it is suggested that isotope shift effects for deuteron and triton in solid D–T would have the same order of magnitude. A procedure for more accurate investigations of the isotope shifts is discussed.

The study of trapping of He+ion in solid hydrogen is important both as a problem in solid state physics and also as an applied physics problem in the field of muon catalyzed fusion (μCF). In μCF, He+ion acts as a trap for μ−, interrupting the chain reaction aspect of the catalytic role of μ−in producing fusion of deuteron and triton and of triton and triton in solid hydrogen composed of 2H–3H and 3H–3H molecules, respectively. Using the Hartree–Fock procedure, combined with procedures for including many-body effects, as well as relaxation effects associated with the He+–H2distances and the adjustment of the H–H separation, we have investigated the trapping of He+in gaseous and solid state environments. For the former, the environment of He+is simulated by a single hydrogen molecule and for the solid by clusters appropriately chosen to represent the hexagonal close-packed structure. Our results for the gaseous state indicate that the trapping is rather strong with a binding energy of 8.5 eV, with almost equal binding energy in the linear and triangular configurations with respect to the H–H direction. For the solid, both the likely sites for He+trapping, namely the tetrahedral and octahedral interstitial sites, are also found to provide deep traps (8.6 eV) of almost equal strength, independent of the orientations of the neighboring molecules, showing that the trapping is not influenced by the orientational disorder in the surrounding hydrogen molecules. Further, the influence of next nearest neighbor hydrogen molecules is found to enhance the trapping energy for He+substantially, by 0.6 eV, with the incorporation of the third nearest neighbors having a much smaller added effect, demonstrating the convergence of our results with respect to the size of the cluster chosen to simulate the solid. The substantial influence on the He+trapping energy found for the neighbors beyond the nearest ones provides an explanation of the greater accumulation of helium in the solid state of hydrogen in μCF experiments as compared to the liquid. Suggestions are made regarding the possible reasons for the almost negligible accumulation of helium in the liquid state.

Precise measurements of the absolute yields and the disappearance rates were carried out for both the X-rays from the (αμ)+ion formed by muon to alpha sticking after the muon catalyzed fusion and for the fusion neutrons from 3He-free liquid and solid D/T mixtures. While the αμ X-ray yield does not contradict the values predicted by the atomic-process theories, the effective sticking probability (ωs) obtained by neutron measurement is much smaller than that from any of the calculations published so far, suggesting, e.g., enhanced reactivation.

The isopropylation of mixtures of 3- and 4-isopropylbiphenyls (3- and 4-IPBPs) was examined over a dealuminated H-mordenite (HM) to elucidate the role of 3- and 4-IPBPs in the isopropylation of biphenyl (BP). 4-IPBP was consumed much faster than 3-IPBP in all cases. 4-IPBP was an exclusive precursor to diisopropylbiphenyls (DIPBs), particularly 4,4′-DIPB, and 4,4′-DIPB was found in encapsulated products during the reaction. These results show that 4-IPBP can allow establishment of an active complex with propylene and acid site in HM pores, whereas 3-IPBP cannot. It is concluded that the isopropylation of BP over HM occurs through a reactant selectivity mechanism, and through a restricted transition state mechanism, but not through a product selectivity mechanism.

BACKGROUND: Leptin, which is the product of the obese gene, is believed to play important roles in pubertal development and reproductive function in females. In a study using adult male rats, it was found that leptin stimulated secretion of gonadotropin from the pituitary in a dose-related manner. However, there has been no such study in female rats. OBJECTIVE: To investigate the effects of leptin on the production of LH and FSH from the pituitary in female rats, using primary cultured pituitary cells. METHODS: In this study, we determined body weight, serum leptin concentration and serum estradiol (E(2)) concentration in female Wistar rats at 3, 5, 6, 7, 9 and 11 weeks of age, and cultured pituitary cells from 6-week-old female Wistar rats with leptin (0--10(-7) mol/l) and GnRH (0 or 10(-8) mol/l). Then basal and GnRH-stimulated extra- and intracellular LH and FSH were assayed by RIA. RESULTS: Serum leptin concentration increased with increases in body weight and E(2) concentration. The pubertal serum leptin concentration was about 10(-10) mol/l. At a lower or moderate concentration, leptin produced dose-related increases in both basal and GnRH-stimulated extra- and intracellular LH and FSH in pituitary cells. At a concentration of 10 mol/l, leptin significantly (P<0.05) stimulated both basal and GnRH-stimulated extra- and intracellular LH and FSH. However, at greater concentrations, these effects diminished. CONCLUSIONS: These results indicated that leptin induced pituitary cells to produce and secrete both LH and FSH, with or without GnRH. The concentration of leptin that induced the greatest production of gonadotropins by pituitary cells was 10(-10) mol/l, which was the same as the physiological pubertal concentration. Leptin may be involved in the onset of puberty. It is also conceivable that leptin may be a cause of ovulatory failure, not only in weight loss but also in weight gain.