Electron-phonon superconductivity in C-doped topological nodal-line semimetal Zr5Pt3: a muon spin rotation and relaxation (µSR) study.

In the present work, we demonstrate that C-doped Zr5Pt3is an electron-phonon superconductor (with critical temperatureTC= 3.8 K) with a nonsymmorphic topological Dirac nodal-line semimetal state, which we report here for the first time. The superconducting properties of Zr5Pt3C0.5have been investigated by means of magnetization, resistivity, specific heat, and muon spin rotation and relaxation (µSR) measurements. We find that at low temperatures, the depolarization rate is almost constant and it can be well described by a single-bands-wave model with a superconducting gap of 2Δ(0)/kBTC= 3.84, somewhat higher than the value of BCS theory. From the transverse field µSR analysis, we estimate the London penetration depthλL= 469 nm, superconducting carrier densityns= 1.83 × 1026 m-3, and effective massm* = 1.428me. The zero field µSR confirms the absence of any spontaneous magnetic field in the superconducting ground state. In order to gain additional insights into the electronic ground state of C-doped Zr5Pt3, we also performed first-principles calculations within the framework of density functional theory (DFT). The observed homogenous electronic character of the Fermi surface as well as the mutual decrease ofTCand density of states at the Fermi level are consistent with the experimental findings of this study. However, the band structure reveals the presence of robust, gapless fourfold-degenerate nodal lines protected by 63screw rotations and glide mirror planes. Therefore, Zr5Pt3represents a novel, unprecedented condensed matter system to investigate the intricate interplay between superconductivity and topology.

Evaluation of PHITS for microdosimetry in BNCT to support radiobiological research.

The aim of this paper is to validate the microdosimetric functionality of the Monte Carlo code, PHITS, and verify its use for estimating dose and RBE for radiobiological studies performed at Kyoto University Institute for Integrated Radiation and Nuclear Science (KURNS). Lineal energy spectra produced by the KUR mixed irradiation mode were measured with a tissue equivalent proportional counter (TEPC) place in free air. The Monte Carlo calculation showed a good agreement with the measured data. In the second part of the study, a realistic set-up of a typical in-vivo radiobiological experiment was simulated with PHITS and the simulation results were compared against TLD and gold foil activation measurements. The Monte Carlo simulation results and the measured data showed an agreement within 3%. The calculated RBE also showed a close value to clinically utilised values. This study shows that PHITS can be utilised to evaluate thermal neutron fluxes and gamma ray absorbed dose rates inside a tumour like medium.

Note: Development of real-time epithermal neutron detector for boron neutron capture therapy.

The real-time detection of epithermal neutrons forms an important aspect of boron neutron capture therapy. In this context, we developed an epithermal neutron detector based on the combination of a small Eu:LiCaAlF6 scintillator and a quartz fiber in order to fulfill the irradiation-field requirements for boron neutron capture therapy. The irradiation test is performed with the use of a reactor-based neutron source. The thermal and epithermal neutron sensitivities of our epithermal neutron detector are estimated to be 9.52 × 10-8 ± 1.59 × 10-8 cm2 and 1.20 × 10-6 cm2 ± 8.96 × 10-9 cm2, respectively. We also subject the developed epithermal neutron detector to actual irradiation fields, and we confirm that the epithermal neutron flux can be measured in realtime.

Effect of porcine placental extract on the mild menopausal symptoms of climacteric women.

OBJECTIVES: This study assessed the effects of oral porcine placental extract (PPE) on the mild menopausal symptoms of climacteric women. METHODS: In this 12-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study, 50 climacteric Japanese women were randomized 1 : 1 to oral PPE (300 mg/day) or placebo. Menopausal symptoms were evaluated by using the Simplified Menopausal Index (SMI), as were serum estradiol (E2) and follicle stimulating hormone (FSH) levels. Blood biochemical and cellular and urinary tests were done to evaluate safety aspects of repeated oral administration of PPE. RESULTS: The total SMI score of the PPE group was significantly more improved after 12 weeks than that of the placebo group (p = 0.031). This score and three subscores (vasomotor, psychological, and somatic symptoms) were significantly improved at 8 and/or 12 weeks compared with the initial values in the PPE group (p < 0.05). E2 and FSH levels were not improved in either group. No adverse events were observed. CONCLUSIONS: Oral PPE at 300 mg/day improved the mild menopausal symptoms of climacteric women. Since oral PPE did not improve serum E2 and FSH levels, PPE is thought not to ameliorate hormonal balance itself but to improve subjective feelings of climacteric women.

Improvement of depth dose distribution using multiple-field irradiation in boron neutron capture therapy.

It is important that improvements are made to depth dose distribution in boron neutron capture therapy, because the neutrons do not reach the innermost regions of the human body. Here, we evaluated the dose distribution obtained using multiple-field irradiation in simulation. From a dose volume histogram analysis, it was found that the mean and minimum tumor doses were increased using two-field irradiation, because of improved dose distribution for deeper-sited tumors.

Dose estimation for internal organs during boron neutron capture therapy for body-trunk tumors.

Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease.

Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography.

It is important to measure the microdistribution of (10)B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of (10)B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×10(9) (cm(-2)s(-1)) and an area of 40mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500mg/kg of boronophenyl-alanine.

Atmospheric burden of organochlorine pesticides in Ghana.

Organochlorine pesticides (OCPs) are subject to the Stockholm Convention on POPs and have been banned or restricted globally. In Ghana, concerns of illicit applications of some OCPs have been raised in recent times. Applying polyurethane foam (PUF) disk passive air samplers (PAS), the levels of OCPs in the atmosphere and their spatial resolution were investigated. It was the first nationwide coverage of OCPs monitoring in Ghana. ∑DDTs and endusulfans constituted the highest burden of atmospheric OCPs in Ghana, at average concentrations of 156±36 and 153±28 pg m(-3), respectively. Mirex had the lowest concentration (0.2±0.01 pg m(-3)). From the chemical signatures of the various OCPs, we deduced that DDT, endosulfans and heptachlor were freshly applied at certain sites, which were all agricultural sites. The OCPs were spatially resolved as a function of the types of crops cultivated in different areas, legacy issues and recent applications.

Radiosensitivity of pimonidazole-unlabelled intratumour quiescent cell population to γ-rays, accelerated carbon ion beams and boron neutron capture reaction.

OBJECTIVES: To detect the radiosensitivity of intratumour quiescent (Q) cells unlabelled with pimonidazole to accelerated carbon ion beams and the boron neutron capture reaction (BNCR). METHODS: EL4 tumour-bearing C57BL/J mice received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all intratumour proliferating (P) cells. After the administration of pimonidazole, tumours were irradiated with γ-rays, accelerated carbon ion beams or reactor neutron beams with the prior administration of a (10)B-carrier. Responses of intratumour Q and total (P+Q) cell populations were assessed based on frequencies of micronucleation and apoptosis using immunofluorescence staining for BrdU. The response of pimonidazole-unlabelled tumour cells was assessed by means of apoptosis frequency using immunofluorescence staining for pimonidazole. RESULTS: Following γ-ray irradiation, the pimonidazole-unlabelled tumour cell fraction showed significantly enhanced radiosensitivity compared with the whole tumour cell fraction, more remarkably in the Q than total cell populations. However, a significantly greater decrease in radiosensitivity in the pimonidazole-unlabelled cell fraction, evaluated using a delayed assay or a decrease in radiation dose rate, was more clearly observed among the Q than total cells. These changes in radiosensitivity were suppressed following carbon ion beam and neutron beam-only irradiaton. In the BNCR, the use of a (10)B-carrier, especially L-para-boronophenylalanine-(10)B, enhanced the sensitivity of the pimonidazole-unlabelled cells more clearly in the Q than total cells. CONCLUSION: The radiosensitivity of the pimonidazole-unlabelled cell fraction depends on the quality of radiation delivered and characteristics of the (10)B-carrier used in the BNCR. ADVANCES IN KNOWLEDGE: The pimonidazole-unlabelled subfraction of Q tumour cells may be a critical target in tumour control.

Effects of employing a ¹°B-carrier and manipulating intratumour hypoxia on local tumour response and lung metastatic potential in boron neutron capture therapy.

OBJECTIVES: To evaluate the effects of employing a (10)B-carrier and manipulating intratumour hypoxia on local tumour response and lung metastatic potential in boron neutron capture therapy (BNCT) by measuring the response of intratumour quiescent (Q) cells. METHODS: B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells. The tumours received reactor thermal neutron beam irradiation following the administration of a (10)B-carrier [L-para-boronophenylalanine-(10)B (BPA) or sodium mercaptoundecahydrododecaborate-(10)B (BSH)] in combination with an acute hypoxia-releasing agent (nicotinamide) or mild temperature hyperthermia (MTH). Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the Q and total (P+Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumour-bearing mice, macroscopic lung metastases were enumerated 17 days after irradiation. RESULTS: BPA-BNCT increased the sensitivity of the total tumour cell population more than BSH-BNCT. However, the sensitivity of Q cells treated with BPA was lower than that of BSH-treated Q cells. With or without a (10)B-carrier, MTH enhanced the sensitivity of the Q cell population. Without irradiation, nicotinamide treatment decreased the number of lung metastases. With irradiation, BPA-BNCT, especially in combination with nicotinamide treatment, showed the potential to reduce the number of metastases more than BSH-BNCT. CONCLUSION: BSH-BNCT in combination with MTH improves local tumour control, while BPA-BNCT in combination with nicotinamide may reduce the number of lung metastases.

Reducing intratumour acute hypoxia through bevacizumab treatment, referring to the response of quiescent tumour cells and metastatic potential.

OBJECTIVES: The aim was to evaluate the influence of bevacizumab on intratumour oxygenation status and lung metastasis following radiotherapy, with specific reference to the response of quiescent (Q) cell populations within irradiated tumours. METHODS: B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2-deoxyuridine (BrdU) to label all proliferating (P) cells. They received γ-ray irradiation following treatment with the acute hypoxia-releasing agent nicotinamide or local mild temperature hyperthermia (MTH) with or without the administration of bevacizumab under aerobic conditions or totally hypoxic conditions, achieved by clamping the proximal end of the tumours. Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the Q and total (P + Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In the other tumour-bearing mice, macroscopic lung metastases were enumerated 17 days after irradiation. RESULTS: 3 days after bevacizumab administration, acute hypoxia-rich total cell population in the tumour showed a remarkably enhanced radiosensitivity to γ-rays, and the hypoxic fraction (HF) was reduced, even after MTH treatment. However, the hypoxic fraction was not reduced after nicotinamide treatment. With or without γ-ray irradiation, bevacizumab administration showed some potential to reduce the number of lung metastases as well as nicotinamide treatment. CONCLUSION: Bevacizumab has the potential to reduce perfusion-limited acute hypoxia and some potential to cause a decrease in the number of lung metastases as well as nicotinamide.

Experimental verification of beam characteristics for cyclotron-based epithermal neutron source (C-BENS).

A cyclotron-based epithermal neutron source has been developed for boron neutron capture therapy. This system consists of a cyclotron accelerator producing 1.1-mA proton beams with an energy of 30 MeV, a beam transport system coupled with a beryllium neutron production target, and a beam-shaping assembly (BSA) with a neutron collimator. In our previous work, the BSA was optimized to obtain sufficient epithermal neutron fluxes of ~10(9) cm(-2) s(-1) using a Monte Carlo simulation code. In order to validate the simulation results, irradiation tests using multi-foil activation at the surface of a gamma-ray shield located behind the collimator and water phantom experiments using a collimated epithermal neutron beam were performed. It was confirmed experimentally that the intensity of the epithermal neutrons was 1.2×10(9) cm(-2) s(-1).

Significance of manipulating tumour hypoxia and radiation dose rate in terms of local tumour response and lung metastatic potential, referring to the response of quiescent cell populations.

The purpose of this study was to evaluate the influence of manipulating intratumour oxygenation status and radiation dose rate on local tumour response and lung metastases following radiotherapy, referring to the response of quiescent cell populations within irradiated tumours. B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells. They received gamma-ray irradiation at high dose rate (HDR) or reduced dose rate (RDR) following treatment with the acute hypoxia-releasing agent nicotinamide or local hyperthermia at mild temperatures (MTH). Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the quiescent (Q) and total (proliferating + Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumour-bearing mice, 17 days after irradiation, macroscopic lung metastases were enumerated. Following HDR irradiation, nicotinamide and MTH enhanced the sensitivity of the total and Q-cell populations, respectively. The decrease in sensitivity at RDR irradiation compared with HDR irradiation was slightly inhibited by MTH, especially in Q cells. Without gamma-ray irradiation, nicotinamide treatment tended to reduce the number of lung metastases. With gamma-rays, in combination with nicotinamide or MTH, especially the former, HDR irradiation decreased the number of metastases more remarkably than RDR irradiation. Manipulating both tumour hypoxia and irradiation dose rate have the potential to influence lung metastasis. The combination with the acute hypoxia-releasing agent nicotinamide may be more promising in HDR than RDR irradiation in terms of reducing the number of lung metastases.

Role of the dipolar interaction on the macroscopic state of magnetic nanoparticle systems: a Monte Carlo study.

We have performed Monte Carlo simulations to treat the effect of the dipolar interaction in assemblies of superparamagnetic nanoparticles. Our simulations reproduce correctly the increase of the blocking temperature (T(B)) as the concentration increases, as observed experimentally. Interestingly, we have observed a progressive displacement of the M2 versus H/M isotherms (Arrott plots) from the origin as the concentration of nanoparticles increases. Moreover, the curvature of the isotherms at T > T(B) changes from positive to negative slope at high sample concentrations, resembling the shape of a first order phase transition. These results are surprisingly similar to that found in a conventional magnetic phase transition under the effect of a random anisotropy or a random field.

A feasibility study of the post-irradiation dose estimation with SPECT technique for BNCT.

Various radioactive nuclei are generated in and around the target volume after the irradiation for boron neutron capture therapy. By measuring and estimating the distributions of these nuclei with the technique of single photon emission computed tomography (SPECT), more accurate post-irradiation dose-estimation can be expected. The feasibility study was performed mainly by simulation. The radioactivity densities for Cl-38, Ca-49 and Na-24 just after the irradiation were calculated to be 100-1000 Bq/cm(3) in and around the target volume. It was confirmed that these nuclei could be detected by SPECT under some conditions. Using the density differences for these generated nuclei, discrimination between soft-tissue area and bone area can be achieved. In focusing on the shallower 1cm(3) voxel, the necessary counting-time for Na-24 was estimated to be a few tens of minutes when the distance between the SPECT detector and the voxel was shortened to 6 cm.

Source identification and concentration distribution of polychlorinated biphenyls in environmental media around industrial complexes.

In order to grasp the concentration distribution and identify sources of PCBs, air and soil samples around Sihwa and Banwol industrial area in Korea were analyzed. In result, the polychlorinated biphenyls (PCBs) concentration of air and soil was ranged from 2.08 to 5.82 ng/m3 (0.0686­1.01 pg WHO-TEQ/m3) and 2.43 to 274 ng/g dry (0.116­60.5 pg WHO-TEQ/g dry), respectively. Air and soil samples showed the very similar isomer composition pattern in each homologue by matrix, respectively. As a result of MLR for soil samples, the whole contribution rate of PCBs products (Aroclor) to soil was ~2 times higher than combustion.

Improvement of dose distribution in phantom by using epithermal neutron source based on the Be(p,n) reaction using a 30 MeV proton cyclotron accelerator.

In order to generate epithermal neutrons for boron neutron capture therapy (BNCT), we proposed the method of filtering and moderating fast neutrons, which are emitted from the reaction between a beryllium target and 30 MeV protons accelerated by a cyclotron, using an optimum moderator system composed of iron, lead, aluminum, calcium fluoride, and enriched (6)LiF ceramic filter. At present, the epithermal-neutron source is under construction since June 2008 at Kyoto University Research Reactor Institute. This system consists of a cyclotron to supply a proton beam of about 1 mA at 30 MeV, a beam transport system, a beam scanner system for heat reduction on the beryllium target, a target cooling system, a beam shaping assembly, and an irradiation bed for patients. In this article, an overview of the cyclotron-based neutron source (CBNS) and the properties of the treatment neutron beam optimized by using the MCNPX Monte Carlo code are presented. The distribution of the RBE (relative biological effectiveness) dose in a phantom shows that, assuming a (10)B concentration of 13 ppm for normal tissue, this beam could be employed to treat a patient with an irradiation time less than 30 min and a dose less than 12.5 Gy-eq to normal tissue. The CBNS might be an alternative to the reactor-based neutron sources for BNCT treatments.

Evaluation of the potential of hexamethylenetetramine, compared with tirapazamine, as a combined agent with {gamma}-irradiation and cisplatin treatment in vivo.

The purpose of this investigation was to compare the effect on intratumour quiescent (Q) cells in vivo of hexamethylenetetramine (HMTA) or tirapazamine (TPZ) in combination with gamma-irradiation and cisplatin treatment. Squamous cell carcinoma (SCC) VII tumour-bearing mice were administered 5-bromo-2'-deoxyuridine (BrdU) continuously to label all intratumour proliferating (P) cells. The mice then received HMTA or TPZ intraperitoneally or continuously with or without gamma-irradiation or cisplatin treatment. Other tumour-bearing mice received HMTA or TPZ intraperitoneally immediately after gamma-irradiation. Immediately after gamma-irradiation or cisplatin treatment following HMTA or TPZ, or 24 h after gamma-irradiation followed by HMTA or TPZ, the response of Q cells was assessed in terms of the micronucleus frequency using immunofluorescence staining for BrdU. The response of all tumour cells (P + Q) was determined from the BrdU-non-treated tumours. HMTA was more toxic to the subset of Q cells than to the population of tumour cells as a whole, similar to the findings for TPZ. The radiosensitising effect of HMTA was similar to that of TPZ in both all cells and Q cells. The recovery-inhibiting effect of HMTA was reliable, but not as great as that of TPZ. The cisplatin sensitivity-enhancing effect of HMTA was similar to or slightly greater than that of TPZ. Continuous administration of both HMTA and TPZ resulted in higher radiosensitivity- and cisplatin sensitivity-enhancing effects than did a single i.p. administration. We concluded that, in terms of the total tumour cell killing effect, including killing of Q cells, gamma-irradiation and cisplatin treatment combined with continuous HMTA administration is a promising strategy given that HMTA is used in clinics.

Treatment results of boron neutron capture therapy using intra-arterial administration of boron compounds for recurrent head and neck cancer.

The effect of boron neutron capture therapy (BNCT) is correlated with the density of boron in the tumour. BNCT using intra-arterial administration of boron compounds was performed for recurrent head and neck cancer. Of the five patients treated, one achieved a complete response and four achieved a partial response. There was one case of transient headache but no severe adverse effects were observed. The advantages of using an intra-arterial administration route for BNCT, which causes the selective killing of tumour cells, might offer a new option in the treatment of recurrent head and neck malignancies. These promising results require further verification and optimization of the BNCT schedule; however, dose escalation would appear to be justified because the toxicity appears to be very low.

Third-order nonlinearity of nickel oxide nanoparticles in toluene.

We report measurements of the nonlinear refractive index, n(2), of nickel oxide nanoparticles (NPs) in toluene at 532 nm. The measurements were performed using the Z-scan technique with 80 ps laser pulses at 7 Hz. Large values of n(2) in the range of 10(-13)-10(-12) cm(2)/W were measured, and negligible two-photon absorption coefficient was estimated for colloids having NP filling fractions in the range of 10(-8)-10(-7).