A new approach based on hydrogen-deuterium exchange is proposed for measuring accessible OH groups in wood. The deuterium (D) exchanged for hydrogen in OH groups in wood was converted to D2O by combustion in oxygen gas then diluted in deionized water, and subsequently determined by 2H NMR spectroscopy. The amount of accessible OH groups in Styrax tonkinensis wood is approximately 6.8 mmol g-1. This measurement is very accurate, with an error of approximately 0.2 mmol g-1. Heat-treated wood has a lower amount of accessible OH groups than non-treated wood. This finding is in agreement with the decreased hygroscopicity of heat-treated wood and explains, at least partially, its increased fungal resistance.

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Fusion performance of reversed shear discharges with an L-mode edge has been significantly improved in a thermonuclear dominant regime with up to 2.8 MA of plasma current in the JT-60U tokamak. The core plasma energy is efficiently confined due to the existence of persistent internal transport barriers formed for both ions and electrons at a large minor radius of r͞a ϳ 0.7 near the boundary of the reversed shear region. In an assumed deuterium-tritium fuel, the peak fusion amplification factor defined for transient conditions involving the dW ͞dt term would be in excess of unity. [S0031-9007(97)04592-4] PACS numbers: 52.55.Fa, 52.55.PiThe reversed shear discharges are considered attractive for a steady state operation with a large bootstrap current fraction in tokamak reactors as proposed for SSTR [1] and ITER [2], since it would be possible to match the hollow current profile to a bootstrap current profile in a steady state. While the central magnetic shear in tokamak plasmas is naturally reversed during a sufficiently long discharge duration with a large bootstrap current fraction [3], the forced shear reversal operation by enhancing a skin current effect has become important for establishing a controlled approach to the steady state [4].In nuclear fusion research, critical conditions in which fusion power produced in plasmas is equal to loss power from the plasmas have been pursued as a crucial milestone ultimately towards the commercial use of thermonuclear fusion energy. In order to determine whether the reversed shear scenario is workable, it is crucially important to demonstrate the fusion-relevant performance, particularly in the thermonuclear fusion regime with the shear reversal operation. So far, however, most of the previous experiments addressing high fusion reactivity in tokamaks have been limited to a hot-ion regime with substantial beam-thermal reactions for deuterium plasmas in TFTR supershot [5], JET hot-ion H mode [6] and JT-60U high-b p H mode [7], and deuterium-tritium (D-T) plasmas in TFTR supershot [8]. Although fusion performance has been recently enhanced with strong profile and shaping control in deuterium reversed shear plasmas with an H-mode edge in DIII-D [9], the projected D-T fusion power is substantially below the loss power from the plasma. In the present paper, it is shown that fusion performance has been significantly improved in JT-60U for reversed shear discharges with an L-mode edge in a thermonuclear fusion regime, so that the transient fusion amplification factor defined as below would be in excess of unity.In JT-60U, the experimental campaign of the reversed shear discharges aiming at high fusion amplification factor ͑Q͒ has been intensively performed with D beams into D plasmas. The confinement properties for the reversed shear discharges created in JT-60U are characterized by (i) the significant reduction of heat and particle transport for electrons as well as ions around the internal transport barrier (ITB), (ii) a large extension of the enhanced confinement region up...

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