Synthesis and Conformational Analysis of N-Aromatic Acetamides Bearing Thiophene: Effect of Intramolecular Chalcogen-Chalcogen Interaction on Amide Conformational Stability.

The conformations of aromatic amides bearing an N-(2-thienyl) or N-(3-thienyl) group were investigated in solution and in the crystal state. NMR spectral data indicate that the conformational preferences of these amides in solution are dependent not only on the relative π-electron densities of the N-aromatic moieties, but also on the three-dimensional relationship between carbonyl oxygen and the N-aromatic moieties. A comparison of the conformational preferences of N-(2-thienyl)amides and N-(3-thienyl)amides revealed that the Z-conformers of N-(2-thienyl)acetamides are stabilized by 1,5-type intramolecular S···O═C interactions between amide carbonyl and thiophene sulfur. The crystal structures of these compounds were similar to the solution structures. The stabilization energy due to 1,5-type intramolecular S···O═C interaction in N-aryl-N-(2-thienyl)acetamides and N-methyl-N-(2-thienyl)acetamide was estimated to be ca. 0.74 and 0.93 kcal/mol, respectively.

Prediction of anatomically and biomechanically feasible precision grip posture of the human hand based on minimization of muscle effort.

We developed a method to estimate a biomechanically feasible precision grip posture of the human hand for a given object based on a minimization of the muscle effort. The hand musculoskeletal model was constructed as a chain of 21 rigid links with 37 intrinsic and extrinsic muscles. To grasp an object, the static force and moment equilibrium condition of the object, force balance between the muscle and fingertip forces, and static frictional conditions must be satisfied. We calculated the hand posture, fingertip forces, and muscle activation signals for a given object to minimize the square sum of the muscle activations while satisfying the above kinetic constraints using an evolutionary optimization technique. To evaluate the estimated hand posture and fingertip forces, a wireless fingertip force-sensing device with two six-axis load cells was developed. When grasping the object, the fingertip forces and hand posture were experimentally measured to compare with the corresponding estimated values. The estimated hand postures and fingertip forces were in reasonable agreement to the corresponding measured data, indicating that the proposed hand posture estimation method based on the minimization of muscle effort is effective for the virtual ergonomic assessment of a handheld product.

A simple and reliable multi-gene transformation method for switchgrass.

KEY MESSAGE: A simple and reliable Agrobacterium -mediated transformation method was developed for switchgrass. Using this method, many transgenic plants carrying multiple genes-of-interest could be produced without untransformed escape. Switchgrass (Panicum virgatum L.) is a promising biomass crop for bioenergy. To obtain transgenic switchgrass plants carrying a multi-gene trait in a simple manner, an Agrobacterium-mediated transformation method was established by constructing a Gateway-based binary vector, optimizing transformation conditions and developing a novel selection method. A MultiRound Gateway-compatible destination binary vector carrying the bar selectable marker gene, pHKGB110, was constructed to introduce multiple genes of interest in a single transformation. Two reporter gene expression cassettes, GUSPlus and gfp, were constructed independently on two entry vectors and then introduced into a single T-DNA region of pHKGB110 via sequential LR reactions. Agrobacterium tumefaciens EHA101 carrying the resultant binary vector pHKGB112 and caryopsis-derived compact embryogenic calli were used for transformation experiments. Prolonged cocultivation for 7 days followed by cultivation on media containing meropenem improved transformation efficiency without overgrowth of Agrobacterium, which was, however, not inhibited by cefotaxime or Timentin. In addition, untransformed escape shoots were completely eliminated during the rooting stage by direct dipping the putatively transformed shoots into the herbicide Basta solution for a few seconds, designated as the 'herbicide dipping method'. It was also demonstrated that more than 90 % of the bar-positive transformants carried both reporters delivered from pHKGB112. This simple and reliable transformation method, which incorporates a new selection technique and the use of a MultiRound Gateway-based binary vector, would be suitable for producing a large number of transgenic lines carrying multiple genes.