Due to the rapid penetration of the Internet of Things (IoT) into human life, illegal access to IoT resources (e.g., data and actuators) has greatly threatened our safety. Access control, which specifies who (i.e., subjects) can access what resources (i.e., objects) under what conditions, has been recognized as an effective solution to address this issue. To cope with the distributed and trust-less nature of IoT systems, we propose a decentralized and trustworthy Capability-Based Access Control (CapBAC) scheme by using the Ethereum smart contract technology. In this scheme, a smart contract is created for each object to store and manage the capability tokens (i.e., data structures recording granted access rights) assigned to the related subjects, and also to verify the ownership and validity of the tokens for access control. Different from previous schemes which manage the tokens in units of subjects, i.e., one token per subject, our scheme manages the tokens in units of access rights or actions, i.e., one token per action. Such novel management achieves more fine-grained and flexible capability delegation and also ensures the consistency between the delegation information and the information stored in the tokens. We implemented the proposed CapBAC scheme in a locally constructed Ethereum blockchain network to demonstrate its feasibility. In addition, we measured the monetary cost of our scheme in terms of gas consumption to compare our scheme with the existing Blockchain-Enabled Decentralized Capability-Based Access Control (BlendCAC) scheme proposed by other researchers. The experimental results show that the proposed scheme outperforms the BlendCAC scheme in terms of the flexibility, granularity, and consistency of capability delegation at almost the same monetary cost.

In contrast to conventional X-ray therapy, proton beam therapy (PBT) can confine radiation doses to tumours because of the presence of the Bragg peak. However, the precision of the treatment is currently limited by the uncertainty in the beam range. Recently, a unique range verification methodology has been proposed based on simulation studies that exploit spherical ionoacoustic waves with resonant frequency (SPIREs). SPIREs are emitted from spherical gold markers in tumours initially introduced for accurate patient positioning when the proton beam is injected. These waves have a remarkable property: their amplitude is linearly correlated with the residual beam range at the marker position. Here, we present proof-of-principle experiments using short-pulsed proton beams at the clinical dose to demonstrate the feasibility of using SPIREs for beam-range verification with submillimetre accuracy. These results should substantially contribute to reducing the range uncertainty in future PBT applications.

b-Carotene is a member of the carotenoid family and is a red-orange pigment abundantly present in many vegetables and fruits. As an antioxidant, it eliminates excessive reactive oxygen species generated in the body. Accordingly, it has potential to be used in the pharmaceutical, food, and cosmetic industries. b-Carotene has a very low water solubility and low bioavailability; thus, there is a need to develop techniques to overcome these issues. In this study, we aimed to enhance the water solubility of b-carotene by using hot-melt technology, a type of solid dispersions technology. When preparing b-carotene solid dispersion using this method, suitable conditions for the emulsifiers and mixing ratios were investigated using water solubility as an index. Setting the weight ratio of bcarotene:polyvinylpyrrolidone:sucrose fatty acid ester to 10%:70%:20% resulted in the poorly-water soluble b-carotene showing improved water solubility (120 lg/mL). The physicochemical properties of the optimized b-carotene solid dispersion were analyzed using field emission scanning electron microscopy, differential scanning calorimetry, and powder X-ray diffraction. The solid dispersion was found to have an amorphous structure. The improved solubility observed for b-carotene in the solid dispersions developed in this work may make these dispersions useful as additives in foods or in nutraceutical formulations. Keywords b-Carotene Á Emulsifier Á Water solubility Á Hot-melt technology Á Solid dispersion Á Amorphous Kenji Ishimoto and Shohei Miki have contributed equally to this work.

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