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Amphiphilic diarylethenes bearing octyloxycarbonyl and N-octylcarbamoyl groups have been designed and synthesized. These ester- and amide-linked compounds form micrometer-sized supramolecular assemblies in water, and these assemblies exhibit photoinduced macroscopic morphological transformations upon alternate irradiation with UV and visible light. The ester-linked diarylethene showed a transformation between colorless spheres and a red-purple hazy fringe, whereas the microspheres of the amide-linked diarylethene showed changes in color, size, and shape, but the spheres did not show division. TEM images revealed that the spheres of the open-ring isomers have coacervate structures, with bicontinuous aqueous and organic phases. The closed-ring isomers of the ester- and amide-linked compounds were found to form nanofibers and thin layers, respectively. These compounds showed absorption spectral shifts at temperatures corresponding to the lower critical solution temperature (LCST) transition. This morphological transformation can be rationalized as the photoinduced phase transition between the high- and low-temperature phases of the LCST transition. These results open up a new avenue for the design of phototransformative supramolecular assemblies based on a combination of photochromism and LCST behavior.

Photoinduced clustering of polystyrene microbeads and photocontrol of their diffusion was achieved in water with the assistance of photoinduced transformation of supramolecular architecture of amphiphilic diarylethene between sphere and fiber states. When a suspension of polystyrene beads containing the sphere state of diarylethene was UV-irradiated from beneath, clustering of the polystyrene beads by thermal convection was observed. The velocity of clustering was dependent on the amount of photogenerated nanofibers that determines the viscosity of the water. Diffusion of the clustered polymer beads was suppressed by the surrounding fibers, but was restored to regular Brownian motion upon irradiation with visible light. It was suggested that the diffusion of the microbeads was controlled by the transformation of aggregates between the more viscous fiber state and the less viscous sphere state. These results provide new insight into the photocontrol of particle motion in fluidic media.

A supramolecular assembly composed of a two-component mixture of amphiphilic diarylethenes, which have octyloxycarbonyl and N-octylcarbamoyl groups, showed a unique macroscopic transformation upon irradiation with UV light and subsequent standing in the dark. Unlike the pure compounds, the assembly was repetitively separated into a blue sphere and a red-purple sparse structure. Both the blue sphere and the sparse structure turned into colorless spheres upon irradiation with visible light and the divided colorless spheres showed the same response to UV and visible light. Phase diagrams based on the change in absorption spectra upon temperature change suggested that the transformation originates from a LCST transition. In the 0.5 : 0.5 mixture, in contrast to the pure compounds, the transition temperature sharply changed at around 50% of the fraction of the closed-ring isomer. TEM imaging showed that the 0.5 : 0.5 mixture with high photoisomerization yield formed a 10 nm-sized network. Judging from the phase diagram and TEM images, the separation is understood as the local phase transition of the regions with a high fraction of the closed-ring isomer.

Quantum yields can be determined by global fitting of prolonged change of concentration against absorbed photon numbers. Quantum yields of synthesized amphiphilic diarylethene in solution and in suspension were analyzed by the global fitting upon irradiation with UV (365 nm) light. Quantum yields of cyclization and cycloreversion reaction in acetonitrile were obtained as 0.59 and 0.013, respectively using the absolute method. In suspension, quantum yield of cyclization was determined as 0.76 using the relative method. The result indicates that the preferred conformation of the open-ring isomer in the aggregate was antiparallel due to the hydrophilic chains and hydrogen bond.

The Mobius3D (M3D) system (Mobius Medical Systems) is a second-check dosimetry system. We investigated the dose calculation accuracy of this system using heterogeneous phantoms with reference beam data provided by the manufacturer using simple and patient plans. We compared the dose distributions between M3D and the treatment planning system, as well as the measurements in solid water phantoms, heterogeneous phantoms, and patient plans for Varian and Elekta accelerators. The M3D results agreed well with the measurements in the solid water phantoms for the simple plans. However, the accuracy of M3D appeared to depend on the type of accelerator, as indicated by the slight differences in the dose measurements. Furthermore, the M3D dose measurements differed by 5-10% in the lung and bone regions. Regarding the patient plans, we confirmed that M3D is reasonably accurate as a second-check system, despite the slight accelerator type-dependent dose difference.

We describe a nickel-catalyzed Suzuki–Miyaura arylation of a tertiary iodocyclopropane with arylboronic acids; this is an efficient and convergent strategy for providing various enantioenriched arylcyclopropanes with a quaternary stereogenic center. This is the first metal-catalyzed coupling between a tertiary alkyl electrophile and a wide range of aromatics, including heteroaromatics. We found that the outcome of the Ni-catalyzed coupling with halides as electrophiles was dependent on the stability of the radical species formed during the reaction. The use of tert-butyl alcohol (t-BuOH) as the reaction solvent was very effective, because of its stability under the radical-generating reaction conditions.

We describe a treatment method with four-dimensional cone-beam computed tomography (4D-CBCT)-guided radiotherapy for gastric lymphoma. We performed image-guided radiotherapy (IGRT) with 15 fractions for a gastric mucosa-associated lymphoid tissue lymphoma patient, using 4D-CBCT. The stomach was delineated based on 4D-CT images. For image guidance, an automatic registration between planning CT and 4D-CBCT images was performed based on the bony anatomy (bone matching), followed by manual registration based on the stomach in 4D-CBCT images of all 10 phases (4D matching). We calculated the covering ratio (CR) with variable stomach-to-planning target volume (PTV) margins, based on the images of all phases [CR (%) = the number of covering phases/all 150 phases × 100]. The patient underwent radiotherapy (RT) as scheduled, without any significant adverse effects. The appropriate PTV margins (CR ≥ 95%) were 25 mm (CR 99.3%) and 15 mm (CR 98.7%) for bone and 4D matching, respectively. 4D matching using 4D-CBCT is appropriate for IGRT of gastric lymphomas.

It is important to understand the coupled processes of sorption and diffusion of radionuclides (RNs) in compacted bentonite, and to develop mechanistic models that can aid in the prediction of the long-term performance of geological disposal systems of radioactive waste. The integrated sorption and diffusion (ISD) model was developed based on the consistent combination of clay–water interaction, sorption and diffusion models. The diffusion model based on the electrical double layer theory describing relative ionic concentrations and viscoelectric effects at the negatively charged clay surface was coupled with porewater chemistry and sorption models. This ISD model was successfully tested for various actinides with a complex chemistry (Np(V), Am(III), U(VI) under conditions where variably charged carbonate complexes are formed) considered in Part 1, by using published diffusion and sorption data (Da, De, Kd) as a function of partial montmorillonite density. Quantitative agreements were observed by consider...

Purpose: This study evaluated the target volume (TV) definition and motion position accuracies of 4D cone-beam computed tomography (CBCT) through comparison with 4D-CT, using a dynamic thorax phantom. Methods: A dynamic thorax phantom was used to acquire 4D images with respiration motion. Targets with 20-mm diameters, motion periods of 3, 4, and 6 s, and 1D and 3D motion patterns corresponding to sin and cos6 curves were used. The TV definition was contoured on all 10 phase images via threshold segmentation on all 4D datasets. The TV union was defined as the internal target volume (ITV). The TV and ITV were compared to the theoretical TVR and ITVR. For motion position evaluation, the TV centroid positions were measured and the root mean square errors (RMSEs) of these measured positions calculated relative to the phantom setup positions. In addition, the breathing patterns of patients with lung tumor were evaluated. Results: The maximum differences in TV and ITV for 4D-CT were 0.66 cm3 and −14.03% for a cos6 motion pattern with a 3-s period, respectively. In contrast, the maximum average differences in TV and ITV for 4D-CBCT were 0.43 cm3 and −6.48%, respectively, for all motion patterns and periods. The 4D-CT and 4D-CBCT RMSEs were within 2.5 mm for most motion patterns. For patient breathing patterns, the average differences in TV, ITV, and positions between 4D-CT and 4D-CBCT were 0.18 cm3, 0.23 cm3, and 1.1 mm, respectively. Conclusions: Although 4D-CT and 4D-CBCT have differences in image acquisition and voxel size, the TV and motion position accuracies for 4D-CBCT are consistent with those of 4D-CT.