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It is well known that the compressive strength of composite laminates decreases after impact load, even if the impact damage is barely visible in appearance. This compression after impact (CAI) strength is one of the most important design criteria for composite structures. Currently, in order to reduce time-consuming model tests and simultaneously ensure structural reliability, analytical or numerical methods are required which are capable of reproducing the actual failure behavior of composite structures (failure mode and load). In this study, impact damage and CAI strength were continuously evaluated by means of numerical progressive failure analysis using dynamic explicit FEA. Since impact and subsequent CAI are dynamic and a static loading processes, respectively, analyses for removing the dynamic effect in the CAI process were performed in the following three steps: 1) impact, 2) relaxation of vibration and 3) CAI. In these analyses, the LaRC failure criteria which take into account fiber-kinking failure mode were employed as stress-based damage initiation criteria, and damage evolution for each lamina was simulated through energy-based damage mechanics. The damage initiation criteria and evolution law were implemented in analyses using the user-subroutine VUMAT of Abaqus/Explicit. In addition, delamination was represented by cohesive elements in stress-based damage initiation criteria and energy-based damage mechanics. As a result of comparison with tests, both of the projected delamination areas caused by impact loading and CAI strength were satisfactorily predicted within an accuracy of ± 15 %. In the CAI simulation, fiber-kinking damage propagated in the direction of width at the maximum applied load, but delamination did not start to propagate. The fiber kinking failure mode was caused by bending due to local buckling at impact area where delamination existed. Accordingly, both of the in-plane fiber kinking damage (which is critical failure mode in CAI) and the delamination (which strongly affects local buckling and subsequent in-plane fiber kinking) are quite important for the accurate prediction of CAI strength.

Strength of compression after impact is one of the most important design criteria for structures using laminated fiber-reinforced plastics. Effects of face-on impact damage on compressive strength have been widely studied over the past decades. However, knowledge about effects of edge-on impact damage is limited compared to that of face-on impact. Therefore, in this study, edge-on impact tests and compression after edge-on impact (CAEI) tests were conducted. In addition, intralaminar fracture toughness (energy) of compressive failure of fiber (0°) and matrix (90°) was obtained by single edge notched compression tests and VCCT analysis, since intralaminar failure properties seem to be essential from our previous work. The obtained toughness was used in progressive damage analysis (PDA) of CAEI failure. In the PDA, CAEI failure was simulated under several modelling assumption of impact damage, including delamination and intralaminar pre-crack. As a result, CAEI strength was predicted with relatively small error when intralaminar pre-crack was included as impact damage. Although modelling assumption of impact damage, such as information about crack length or cracking ply, has to be validated based on experimental observation as future task, utility to predict CAEI strength by modelling impact damage as pre-crack was shown.

Purine-rich foods have long been suspected as a major cause of hyperuricemia. We hypothesized that inhibition of human concentrative nucleoside transporter 2 (hCNT2) would suppress increases in serum urate levels derived from dietary purines. To test this hypothesis, the development of potent hCNT2 inhibitors was required. By modifying adenosine, an hCNT2 substrate, we successfully identified 8-aminoadenosine derivatives as a new class of hCNT2 inhibitors. Compound 12 moderately inhibited hCNT2 (IC50 = 52 ± 3.8 μM), and subsequent structure-activity relationship studies led to the discovery of compound 48 (IC50 = 0.64 ± 0.19 μM). Here we describe significant findings about structural requirements of 8-aminoadenosine derivatives for exhibiting potent hCNT2 inhibitory activity.

Various toughened-material systems to reinforce interlaminar strength of CFRP have been proposed on the basis of the results of coupon tests. In this paper, an applicability of toughened-material systems to structural model such as curved beam subject to static bending was examined. Two kinds of CFRP with different toughened-material system were selected, and both microscopic observation and numerical FEM simulation using VCCT were performed for test results. A difference between coupon and structural model tests was found for the case of the curved beam with artificial anomaly, and the cause was considered due to the difference of delamination pass between coupon and curved beam tests. From a view point of numerical simulation for predicting the strength behavior of the curved beam, an adoption of different fracture toughness from that by coupon test was necessary.

The reverse aromatic Cope rearrangement of 2-allyl-3-alkylideneindolines obtained by Horner-Wadsworth-Emmons olefination of 2-allylindolin-3-ones was performed. When 2-allylindolin-3-ones were treated with phosphonium ylides in refluxing toluene, domino Wittig reaction and reverse aromatic Cope rearrangement took place to give alpha-allyl-3-indole acetate derivatives in good yields. The aromatization as a new driving force in the Cope rearrangement is preferable to the conjugation with the carbonyl and cyano groups and also to the alkyl substitution pattern, which are well-known driving forces.

2-Alkyl-1,2-dihydroindol-3-ones are prepared from readily available 1-acetyl-2-methoxy-1,2-dihydroindol-3-one by alkylation reduction with sodium borohydride, and demethoxylation of the resulting 3-hydroxy-2-methoxy-4,3-dihydroindoles with Lewis acids. The stereochemistry of the reduction is also described.

3-Alkylindoles can be conveniently prepared by the Wittig reaction of 1-acetyl-indol-3(2H)-ones with the stabilized phosphonium ylides

3-Oxygenated carbazoles are prepared in 4 steps from 1 -acetyl-2-methoxy-1,2-dihydroindol-3-one 6 by Wittig reaction with phosphonium ylides 10 to afford the 3-alkylindoles 11, followed by silylation to the silyl enol ethers 12. Electrocyclic reaction of the enol ethers 12 followed by desilylation give the 3-hydroxycarbazoles 15. The carbazoles 15a, b were converted into the carbazole alkaloid hyellazole 1 and 4-deoxycarbazomycin B 2c, respectively.

The Wittig reaction of 1-acetyl-2-methoxy-(1) and 1 -acetyl-2-hydroxyindol-3(2H)-one (2) with stabilized and semistabilized ylides gave predominantly 3-alkylidenedihydroindoles (4), (7), and (13) with (Z)-stereochemistry. When the Wittig reaction was carried out under more drastic conditions, the Wittig products (4) and (7) isomerized to afford 3-alkylindoles (5) and the indol-2-one (8), respectively. These isomerizations are also described.

3-Alkylindoles can be conveniently prepared by the Wittig reaction of 1-acetyl-indol-3(2H)-ones with the stabilized phosphonium ylides

3-Oxygenated carbazoles are prepared in 4 steps from 1 -acetyl-2-methoxy-1,2-dihydroindol-3-one 6 by Wittig reaction with phosphonium ylides 10 to afford the 3-alkylindoles 11, followed by silylation to the silyl enol ethers 12. Electrocyclic reaction of the enol ethers 12 followed by desilylation give the 3-hydroxycarbazoles 15. The carbazoles 15a, b were converted into the carbazole alkaloid hyellazole 1 and 4-deoxycarbazomycin B 2c, respectively.

2-Alkyl-1,2-dihydroindol-3-ones are prepared from readily available 1-acetyl-2-methoxy-1,2-dihydroindol-3-one by alkylation reduction with sodium borohydride, and demethoxylation of the resulting 3-hydroxy-2-methoxy-4,3-dihydroindoles with Lewis acids. The stereochemistry of the reduction is also described.

The Wittig reaction of 1-acetyl-2-methoxy-(1) and 1 -acetyl-2-hydroxyindol-3(2H)-one (2) with stabilized and semistabilized ylides gave predominantly 3-alkylidenedihydroindoles (4), (7), and (13) with (Z)-stereochemistry. When the Wittig reaction was carried out under more drastic conditions, the Wittig products (4) and (7) isomerized to afford 3-alkylindoles (5) and the indol-2-one (8), respectively. These isomerizations are also described.

A short synthesis of hyellazole (1) based on a new method of benzannelation of indoles which involves cyclization of 3-buta -1,3-dienylindole (6) is described.

A short synthesis of hyellazole (1) based on a new method of benzannelation of indoles which involves cyclization of 3-buta -1,3-dienylindole (6) is described.