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Reduction of interlayer Co2+ ions in expandable fluorine mica has been attempted. The polyol process using diethylene glycol as a reducing agent was employed. The co2+ -exchanged mica was refluxed at about 225–235 °C in liquid diethylene glycol for 10–120 minutes. Consequently, zero-valence Co metal (Co0) intercalated mica having a metallic grey colour was obtained by in situ reduction of interlayer Co2+ ions, showing different properties from Co2+ -exchanged mica as a precursor. The layer charge of Co-metal-intercalated mica is compensated by protons which are produced through the course of reduction of interlayer Co2+ ions. The reduced sample heated at 350 °C, which had no organic molecules, exhibited a basal spacing of 1.28 nm, indicating the presence of 0.34 nm cobalt metal clusters after subtracting the thickness of the host silicate layer. During the process of reduction in diethylene glycol, cobalt metal particles were expelled from the interlayers which grew to about 0.5 μm onto the external surfaces of host mica crystals with increasing refluxing time. [ABSTRACT FROM AUTHOR]

Anisotropic optical properties are investigated on β-Ga2O3 films and a single crystal by spectroscopic ellipsometry measurements. The films grown on (0001) α-Al2O3 contain threefold in-plane rotational domains, and the refractive index and absorption coefficient α obtained by assuming an isotropic material are found to be smaller than those in the single crystal. By measuring the off-normal transmission ellipsometry spectra of the (010) β-Ga2O3 substrate, the optical anisotropy in a biaxial crystal as well as the gradual increase in α are recognized as origins of the scattering in optically determined bandgap energies. [ABSTRACT FROM AUTHOR]

Single-phase rocksalt-structured MgxZn1−xO (x > 0.5) alloy films were grown on MgO substrates using the mist chemical vapor deposition method. A specular surface with a step and terrace structure was obtained. The bandgap was tuned from 5.9 to 7.8 eV as x varied from 0.5 to 1. Deep ultraviolet cathodoluminescence, stemming from near band edge transitions, was observed for Mg0.57Zn0.43O in the 4.8–5.5 eV range, peaking at ∼5.1 eV (∼240 nm) in the 12–100 K range. [ABSTRACT FROM AUTHOR]

A molecular beam epitaxy (MBE) chamber dedicated to nitride growth was developed at the synchrotron radiation facility SPring-8. This chamber has two beryllium windows for incident and outgoing X-rays, and is directly connected to an X-ray diffractometer, enabling in situ synchrotron X-ray measurements during the nitride growth. Experimental results on initial growth dynamics in GaN/SiC, AlN/SiC, and InN/GaN heteroepitaxy were presented. We achieved high-speed and high-sensitivity reciprocal space mapping with a thickness resolution of atomic-layer scale. This in situ measurement using the high-brilliance synchrotron light source will be useful for evaluating structural variations in the initial growth stage of nitride semiconductors. [ABSTRACT FROM AUTHOR]

The polarized transmittance and reflectance spectra of β-Ga2O3 crystals are investigated, and the data are interpreted in terms of the monoclinic crystal band structure. The energies of the absorption edge can be divided into six ranges, and these ranges can be assigned to the transitions from the valence bands to the conduction band minimum according to the selection rules. The indirect bandgap-energy of 4.43 eV is smaller than the direct bandgap-energy of 4.48 eV at RT; and the energy difference of 0.05 eV nearly matches the theoretically calculated values of 0.03–0.04 eV. [ABSTRACT FROM AUTHOR]

The effects of AlOx formation on the emission properties of AlN/GaN heterostructures are comparatively investigated using steady-state and time-resolved photoluminescence (PL) measurements. By analyzing the excitation power and temperature-dependent PL spectra, PL at around 3.45–3.46 eV is attributed to the two-dimensional electron-gas (2DEG)-related emission. Simultaneous changes in the emission energies and lifetimes are observed by forming a crystallized AlOx layer. The results demonstrate a possibility of controlling the surface states by changing the surface oxide structure. [ABSTRACT FROM AUTHOR]

To evaluate the polarity, energy band diagram, and oxygen (O) distribution of a heavily Mg-doped InN (InN:Mg+) epilayer with a Mg concentration of 1.0±0.5×1020cm-3, the core-level and valence band (VB) photoelectron spectra are investigated by angle-resolved soft and hard X-ray photoelectron spectroscopies. The InN:Mg+ epilayers are grown by radio-frequency plasmaassisted molecular beam epitaxy. In this doping level, the polarity inversion from In-polar to N-polar occurs with the increase in the Mg flow rate under the same growth conditions, and the VB spectrum clearly indicates the direction of polarity of InN:Mg+, which is N-polar. The energy band diagram is considered to exhibit a two-step downward bending structure due to the coexistence of the n+ surface electron accumulation layer and heavily Mg-doped p+ layer formed in the bulk. The O concentration rapidly increases until ∼4 nm with respect to the surface, which is deduced to be one of the reasons of the formation of the anomalous two-step energy band profile. [ABSTRACT FROM AUTHOR]

Advances in genetic sequencing and other diagnostic technologies have enabled the use of precision medicine in clinical cancer care, as well as the development of novel therapies that are targeted to specific molecular drivers of cancer. Developing these new agents and making them accessible to patients requires global clinical studies and regulatory review and approval by different national regulatory agencies. Whereas these global trials present challenges for drug developers who conduct them and regulatory agencies who oversee them, they also raise practical issues about patients with low-frequency cancers who need these therapies. A lack of uniform standards in both regulatory approval for marketing and reimbursement for approved agents across countries may make the newly developed agent either unavailable or inaccessible to patients in certain countries or regions, even if patients from those countries or regions participated in the clinical research that established the safety and efficacy of the agent. In an effort to further understand and address this need, we convened an international workshop in 2017 in North Bethesda, MD. After presentations of the individual regulatory pathways for marketing approval and reimbursement for individual nations, participants discussed expedited pathways and specific challenges for uncommon cancers. As a matter of justice, agents being developed for rare cancers, pediatric cancers, or uncommon molecular subsets of common cancers need a pragmatic, science-based regulatory policy framework to clearly specify the type and quantity of evidence needed to demonstrate efficacy from these trials and evidence to support accessibility.