Glass transition temperature control by poly(norbornene-dicarboximide) copolymers

Polymer Bulletin - By the precise combination of both cyclohexyl- and octyl-substituted norbornene-dicarboximide monomers, a series of copolymers were prepared by ring-opening metathesis...     

Cyclopolymerization of 1,6-heptadienes and 1,6,11-dodecatrienes having acyclic substituents catalyzed by Pd-diimine complexes

Polymer Bulletin - Chloro(methyl)palladium complexes with 1,2-diimine ligand catalyze the cyclopolymerization of 1,6-heptadienes having two alkoxymethyl substituents at 4-position. The obtained...     

Facetons: face primitives for building 3D architectural models in virtual environments

We present facetons, geometric modeling primitives designed for building architectural models especially effective for a virtual environment where six degrees of freedom input devices are available. A faceton is an oriented point floating in the air and defines a plane of infinite extent passing through the point. The polygonal mesh model is constructed by taking the intersection of the planes associated with the facetons. With the simple interaction of faceton, users can easily create 3D architecture models. The faceton primitive and its interaction reduce the overhead associated with standard polygonal mesh modeling, where users have to manually specify vertexes and edges which could be far away. The faceton representation is inspired by the research on boundary representations (B‐rep) and constructive solid geometry, but it is driven by a novel adaptive bounding algorithm and is specifically designed for 3D modeling activities in an immersive virtual environment. We describe the modeling method and our current implementation. The implementation is still experimental but shows potential as a viable alternative to traditional modeling methods. Copyright © 2014 John Wiley & Sons, Ltd.     

Adult headform impact tests of three Japanese child bicycle helmets into a vehicle

The head is the body region that most frequently incurs fatal and serious injuries of cyclists in collisions against vehicles. Many research studies investigated helmet effectiveness in preventing head injuries using accident data. In this study, the impact attenuation characteristics of three Japanese child bicycle helmets were examined experimentally in impact tests into a concrete surface and a vehicle. A pedestrian adult headform with and without a Japanese child bicycle helmet was dropped onto a concrete surface and then propelled into a vehicle at 35 km/h in various locations such as the bonnet, roof header, windshield and A-pillar. Accelerations were measured and head injury criterion (HIC) calculated. In the drop tests using the adult headform onto a concrete surface from the height of 1.5 m, the HIC for a headform without a child helmet was 6325, and was reduced by around 80% when a child helmet was fitted to the headform. In the impact tests, where the headform was fired into the vehicle at 35 km/h at various locations on a car, the computed acceleration based HIC varied depending on the vehicle impact locations. The HIC was reduced by 10–38% for impacts headforms with a child helmet when the impact was onto a bonnet-top and roof header although the HIC was already less than 1000 in impacts with the headform without a child helmet. Similarly, for impacts into the windshield (where a cyclist’s head is most frequently impacted), the HIC using the adult headform without a child helmet was 122; whereas when the adult headform was used with a child helmet, a higher HIC value of more than 850 was recorded. But again, the HIC values are below 1000. In impacts into the A-pillar, the HIC was 4816 for a headform without a child helmet and was reduced by 18–38% for a headform with a child helmet depending on the type of Japanese child helmet used. The tests demonstrated that Japanese child helmets are effective in reducing accelerations and HIC in a drop test using an adult headform onto a relatively rigid hard surface, i.e., simulating a road surface or concrete path. However, when the impact tests are into softer surfaces, the child helmet’s capacity to decrease accelerations is accordingly reduced. Impacts into the windshield, while below the critical HIC value of 1000, indicated higher HIC values for a headform with a child helmet compared to an adult headform without a child helmet. The unpredictable nature of the results indicates further research work is required to assess how representative the stiffness of an adult headform is when compared to an actual head.     

Analysis of hair follicle penetration of lidocaine and fluorescein isothiocyanate-dextran 4 kDa using hair follicle-plugging method

Objective: Skin appendages including hair follicles (hfs) and the stratum corneum (sc) are beginning to be recognized as important permeation pathways for the skin permeation of drugs, but their detailed role is not yet clear. To investigate the contribution of hfs to drug permeation, we conducted skin permeation tests by controlling the hf contribution with a hf-plugging method.

Method: Lidocaine (LC) and fluorescein isothiocyanate-dextran 4?kDa (FD-4) were selected as model drugs and pig ear skin was used as model skin.

Results: Skin permeabilities of ionized LC and FD-4 decreased with hf-plugging, whereas no change was observed for the skin permeation of unionized LC. A fairly good correlation was found for ionized LC and FD-4 between skin permeability and the number of hfs plugged. Permeation parameters of model drugs for both skin pathways were calculated utilizing Fick's second law of diffusion. Consequently, the sc pathway could highly contribute to the permeation of unionized LC, since unionized LC shows markedly high partition to the sc. In contrast, the hf pathway could contribute to the permeation of ionized LC and FD-4, since these had high distributions to the hf pathway in spite of its very small surface area relative to whole skin surface area.

Conclusion: The hf pathway must be important for the skin permeation of ionized compounds and hydrophilic high molecular compounds. hf-plugging is also a useful method for assessing the skin permeability of compounds through the hf pathway.     

Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

Fracture sealing by precipitation is known to occur in high-strength and ultra-low-permeability concrete (HSULPC) immersed in water. Because a high ability to retard radionuclide migration is required for HSULPC, understanding both the sealing process and the composition of sealing deposits is important to identify optimum conditions for significant sealing. In this study, sealing of a macro-fractured HSULPC specimen with initial aperture of approximately 0.1 mm was investigated in simulated seawater over 49 days. The composition of sealing deposits at 49 days after immersion was clarified by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), and the progress of sealing during the 49 days was clarified by image analysis with micro-focus X-ray computed tomography (X-rayCT). Both the SEM/EDX and X-rayCT results showed that significant sealing was attained only near the outermost part of the specimen. The SEM/EDX results showed that a thin brucite layer formed on the entire specimen surface over which significant precipitation of calcium carbonate occurred and sealed the macro-fracture only near the outermost part of the specimen. The X-rayCT results indicated that the amount of sealing deposits in the macro-fracture ( \(P_\mathrm{seal})\) reached 70 % in the mostly sealed region at 49 days and the rate of change in \(P_\mathrm{seal}\) became maximum \((3.7\,\% \hbox { day}^{-1})\) during 7–21 days after immersion, then decreased. In conclusion, the findings in this study represent an important clue in the search for optimum conditions to achieve fracture sealing in HSUPLC.     

Applicability of performance improvement method of existing steel railway bridges by installing concrete decks

Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of them have problems such as corrosion and fatigue. In this study, we proposed a method to improve the performance, such as the load-carrying capacity, of the existing steel railway bridges by installation of concrete decks. To figure out the applicability of the proposed method, we discussed the applicable range of span and the effect of stress reduction. Considering application into actual bridges, we proposed an installation method using pre-cast concrete decks and girder-deck connection with filler mortar and steel fasteners. Finally, we carried out loading tests of the connection with fasteners and bending tests of the applied girders. As a result, we found that the girder-deck connections have enough static capacity for lateral force and train loads, under the condition that the studs are installed and the gaps between the pre-cast decks are filled with mortar.     

Tungsten-mediated synthesis of triazafluorenes

Reaction of 2-pyridinecarboxaldehyde with aliphatic 1,2-diamines in aqueous/ethanolic solution mediated by [W(CN)₄O₂]⁴⁻ affords the cationic disubstituted triazafluorenes in good yields. Single-crystal X-ray analysis of 4,9-bis(2-pyridyl)-4a,9a-dihydro-3H,9H-3,8a,9a-triazafluorenium hexafluorophosphate salt 1 reveals the formation of a novel heterocyclic tricycle, triaza analogue of fluorene. The identity and purity of the compounds have been verified with elemental analysis as well as IR, ¹H and ¹³C NMR, UV–Vis, Raman and cyclic voltammetry measurements. Aliphatic 1,3- and 1,4-diamines as well as cycloaliphatic and aromatic ones are not reactive. The proposed pathway for the tungsten-mediated formation of triazafluorenes is discussed.     

Adhesion properties of swollen hydrogels evaluated by a point‐contact method

The adhesion of swollen hydrogels was studied with the use of a simple tack‐evaluation technique using a point contact in the air at room temperature. The hydrogels used here were poly(sodium acrylate) gel physically crosslinked by aluminum ions. The adhesion properties were examined under different experimental parameters, i.e., separation velocities, normal loads, and waiting periods prior to separation. The effects of the material parameters resulting from the different degrees of the crosslinking on the adhesive properties were also examined. As a result, the adhesion force and the separation energy showed a power‐law behavior with different powers, which depended on the experimental and material parameters. The adhesion properties were determined by the bulk viscoelasticity as well as the surface physical and chemical properties. The results were discussed in terms of the surface molecular interaction and the bulk viscoelastic and viscous properties on the basis of the measurements of the apparent contact area, the ATR FTIR spectrum, and the dynamic viscoelasticity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007