[en] 1-(2',2',3'-Tricyano-3-carbomethoxycyclopropyl)-3,4-di-(2'- hydroxyethoxy)benzene (4) was prepared by the reaction of bromomalononitrile with methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3). Diol 4 was condensed with tolylene-2,-4-diisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, and 1,6-hexamethylenediisocyanate to yield polyurethanes 5,6 and 7 containing tricyanocyclopropane functionalities in the pendant group. The resulting polymers 5-7 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25-0.30 dL/g. Polyurethanes 5-7 showed a thermal stability up to 300.deg.C in TGA thermograms. Solution-cast films showed T_g values in the range of 100-125.deg.C and piezoelectric coefficients (d₃₁) of the poled polymer films were 1.3-2.0 pC/N, which are acceptable for piezoelectric device applications.

[en] A novel T-type polyester 7 containing 1-(2,5-dioxyphenyl)-2-{5-(1,2,2-tricyanovinyl)-2-thienyl}ethenes as nonlinear optical (NLO) chromophores, which are part of the polymer backbone, was prepared and characterized. Polyester 7 is soluble in common organic solvents such as dimethylsulfoxide and N,N-dimethylformamide. It showed a thermal stability up to 300 .deg. C in thermogravimetric analysis thermogram and the glass-transition temperature (T_g) obtained from differential scanning calorimetry thermogram was around 113 .deg. C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer films at 1,560 nm fundamental wavelength was around 1.85 pm/V. The dipole alignment exhibits a greater thermal stability even at 10 .deg. C higher than T_g, and there is no SHG decay below 125 .deg. C due to the partial mainchain character of the polymer structure, which is acceptable for nonlinear optical device applications

[en] Two approaches to minimize the randomization have been proposed. One is to use cross-linking method and the other is to utilize high T_g polymers such as polyimides. Polyurethane matrix forms extensive hydrogen bond between urethane linkage and increases rigidity preventing the relaxation of induced dipoles. Recently we reported a novel Y-type NLO polyurethanes with high thermal stability of second harmonic generation. This work is now extended to the synthesis of another NLO polyurethanes. In this work we prepared novel polyurethanes containing 2,3-dioxybenzylidenecyanoacetate group as a NLO-chromophore. We selected 2,3-dioxybenzylidenecyanoacetate group as NLO-chromophore because it will have a large dipole moment and is rather easy to synthesize. Furthermore 2,3-dioxybenzylidenecyanoacetate group constitutes a novel Y-type NLO polyurethanes, and these Y-type NLO polyurethanes are not presented in the literature. Thus, we designed and synthesized a new type of NLO polyurethane, in which the pendant NLO chromophores are parts of the polymer backbones. These mid-type NLO polymers are expected to have both of the merits of main chain- and side chain-NLO polymers; stabilization of dipole alignment and good solubility. After confirming the structure of the resulting polymers we investigated the properties such as morphology of polymer film, second harmonic generation (SHG) activity and relaxation of dipole alignment

[en] Methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate was prepared and condensed with terephthaloyl chloride to yield novel Y-type polyester containing 3,4-dioxybenzylidenecyanoacetate groups as NLO-chromophores, which constituted parts of the polymer main chains. The resulting polymer 4 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymer 4 shows thermal stability up to 280 .deg. C in thermogravimetric analysis with glass-transition temperature obtained from differential scanning calorimetry near 105 .deg. C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength is around 2.42 pm/V. The dipole alignment exhibits high thermal stability up to near T_g, and there is no SHG decay below 100 .deg. C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications

[en] The promise of NLO polymers lies in their higher nonlinear optical activity, faster response time, and easy fabrication into electro-optic devices. In the developments of NLO polymers for electrooptic device applications, stabilization of electrically induced dipole alignment is one of important considerations; in this context, two approaches to minimize the randomization have been proposed, namely the use of cross-linked systems and the utilization of polymers with high glass transition temperature (T_g) such as polyimides. A polyurethane matrix forms extensive hydrogen bonding between urethane linkages, with increased rigidity preventing the relaxation of induced dipoles. Polyurethanes functionalized with hemicyanine and thiophene ring in side chain show an enhanced thermal stability of aligned dipoles. Polyurethanes with NLO chromophores, whose dipole moments are aligned transverse to the main chains, show large second-order nonlinearity with good thermal stability

[en] In the developments of NLO polymers for electro-optic device applications, stabilization of electrically induced dipole alignment is one of important criteria; in this context, two approaches have been proposed to minimize the randomization of dipole alignment, namely the use cross-linking method and the utilization of high T_g polymers such as polyimides. Various polyesters with NLO chromophores in the main chain or in side chain have been prepared and their properties studied. In general, main-chain NLO polymers have good thermal stability of dipole alignments, but they often do not dissolve in organic solvents, and their intractability make them unusable to fabricate stable films. Side-chain NLO polymers have the advantages such as good solubility and homogeneity relative to the main-chain systems, but they often suffer from poor stability of dipole alignments at high temperatures. Recently we have prepared novel polyesters containing dioxy-nitrostilbene or dioxybenzylidenemalononitrile as NLO chromophores. The resulting polymers exhibit enhanced thermal stability of second harmonic generation (SHG), which stems from the stabilization of dipole alignment of the NLO chromophore. In this work reported here, we prepared another novel polyester containing 2,5-dioxybenzylidenecyanoacetate groups as NLO chromophores. We selected the latter because they have a large dipole moment and are rather easy to synthesize. Furthermore, 2,5-dioxybenzylidenecyanoacetate group constitutes novel T-type NLO polyester, and this T-type NLO polyester has not yet been reported in the literature. Thus, we synthesized a new type of NLO polyester, in which the pendant NLO chromophores are components of the polymer backbone. This T-type NLO polymer is expected to have the advantages of both main-chain and side-chain NLO polymers namely stable dipole alignment and good solubility

[en] The promise of NLO polymers lies in their higher nonlinear optical activity, faster response time, and easy fabrication into electro-optic devices. In the developments of NLO polymers for electrooptic device applications, stabilization of electrically induced dipole alignment is one of important considerations; in this context, two approaches to minimize the randomization have been proposed, namely the use of cross-linked systems and the utilization of polymers with high glass transition temperature (T_g) such as polyimides. A polyurethane matrix forms extensive hydrogen bonding between urethane linkages, with increased rigidity preventing the relaxation of induced dipoles. Polyurethanes functionalized with hemicyanine and thiophene ring in side chain show an enhanced thermal stability of aligned dipoles. Polyurethanes with NLO chromophores, whose dipole moments are aligned transverse to the main chains, show large second-order nonlinearity with good thermal stability

[en] New Y-type polyester (3) containing nitrophenylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. Polyester 3 is soluble in common organic solvents such as N,N-dimethylformamide and acetone. It shows a thermal stability up to 240 .deg. C in thermogravimetric analysis with glass-transition temperature (T_g) obtained from differential scanning calorimetry near 116 .deg. C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at the 1064 nm fundamental wavelength is around 4.63 x 10^-9 esu. The dipole alignment exhibits a thermal stability even at 4 .deg. C higher than T_g, and there is no SHG decay below 120 .deg. C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications

[en] Owing to the developments in imaging modalities, imaging has become an essential element in the early evaluation of and decision-making algorithm for patients with trauma. In particular, CT technology has developed over the past decades, resulting in faster image acquisition and higher image quality. Currently, CT is the key imaging modality for triaging surgical and non-surgical treatment in patients with abdominal trauma and plays an important role in increasing the frequency and success rate of non-surgical treatment. Because rapid and accurate diagnosis of injury in patients with trauma can improve the patients' prognosis, radiologists should be familiar with the imaging findings, especially the CT findings, in patients with trauma. In this article, the authors reviewed the considerations when performing CT for evaluating abdominal trauma. In addition, they described the important imaging findings and pitfalls when diagnosing blunt trauma in various intra-abdominal organs

[en] Three-dimensional printing (3DP) is a rapid prototyping technique that can create complex 3D structures by inkjet printing of a liquid binder onto powder biomaterials for tissue engineering scaffolds. Direct fabrication of scaffolds from 3DP, however, imposes a limitation on material choices by manufacturing processes. In this study, we report an indirect 3DP approach wherein a positive replica of desired shapes was printed using gelatin particles, and the final scaffold was directly produced from the printed mold. To create patient-specific scaffolds that match precisely to a patient's external contours, we integrated our indirect 3DP technique with imaging technologies and successfully created custom scaffolds mimicking human mandibular condyle using polycaprolactone and chitosan for potential osteochondral tissue engineering. To test the ability of the technique to precisely control the internal morphology of the scaffolds, we created orthogonal interconnected channels within the scaffolds using computer-aided-design models. Because very few biomaterials are truly osteoinductive, we modified inert 3D printed materials with bioactive apatite coating. The feasibility of these scaffolds to support cell growth was investigated using bone marrow stromal cells (BMSC). The BMSCs showed good viability in the scaffolds, and the apatite coating further enhanced cellular spreading and proliferation. This technique may be valuable for complex scaffold fabrication. (paper)