Biodegradable homopolyesters such as poly(butylene succinate) (PBSU) and poly(butylene adipate) (PBAD) and copolyesters such as poly(butylene succinate‐co‐butylene adipate) (PBSA) were synthesized, respectively, from succinic acid (SA) and adipic acid (AA) with 1,4‐butanediol through a two‐step process of esterification and deglycolization. The polyester compositions and physical properties of both homopolyesters and copolyesters were investigated by 1H– and 13C–NMR, DSC, GPC, WAXD, and optical polarizing microscopy. The melting point (Tm) of these copolyesters decreased gradually as the contents of butylene adipate increased and the glass‐transition temperature (Tg) of these copolyesters decreased linearly as the contents of the adipoyl unit increased. PBSA copolyesters showed two types of XRD patterns of PBSU and PBAD homopolyesters. Furthermore, the biodegradation and hydrolytic degradation of the high molecular weight PBSU homopolyester, PBAD homopolyester, and PBSA copolyesters were investigated in the composting soil and NH4Cl aqueous solutions at a pH level of 10.6. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2808–2826, 2001

Biodegradable homopolyesters such as poly(butylene succinate) (PBSU) and poly(butylene adipate) (PBAD) and copolyesters such as poly(butylene succinateco-butylene adipate) (PBSA) were synthesized, respectively, from succinic acid (SA) and adipic acid (AA) with 1,4-butanediol through a two-step process of esterification and deglycolization. The polyester compositions and physical properties of both homopolyesters and copolyesters were investigated by 1 H-and 13 C-NMR, DSC, GPC, WAXD, and optical polarizing microscopy. The melting point (T m ) of these copolyesters decreased gradually as the contents of butylene adipate increased and the glass-transition temperature (T g ) of these copolyesters decreased linearly as the contents of the adipoyl unit increased. PBSA copolyesters showed two types of XRD patterns of PBSU and PBAD homopolyesters. Furthermore, the biodegradation and hydrolytic degradation of the high molecular weight PBSU homopolyester, PBAD homopolyester, and PBSA copolyesters were investigated in the composting soil and NH 4 Cl aqueous solutions at a pH level of 10.6.

The resistive switching characteristics of Au/ Pr 0.7 Ca 0.3 MnO 3 ͑PCMO͒ / Pt sandwich structure were investigated by changing growth temperature of the PCMO film, adding an oxygen annealing process, and modifying the Au/PCMO/Pt sandwich structure by inserting a PrMnO 3 ͑PMO͒ or CaMnO 3 ͑CMO͒ layer at the Au/PCMO interface. From these experiments, we obtained the following results. First, only crystalline PCMO films exhibited reversible resistive switching behavior in Au/PCMO/Pt sandwich structure. Secondly, the Mn 4+ /Mn 3+ ratio at the PCMO surface was changed by oxygen annealing of the PCMO film, resulting in an increase of the resistance ratio of high resistance state and low resistance state. Lastly, we could not observe the resistive switching behavior in Au/PMO/PCMO/Pt and Au/CMO/PCMO/Pt sandwich structures. The resistive switching behavior could be observed only in Au/PCMO/PMO͑or CMO͒/PCMO/Pt sandwich structure. These results indicate that the resistive switching of Au/PCMO/Pt sandwich structure depends on the mixed valence state Mn 4+ /Mn 3+ of Mn ions in the metal/PCMO interface domains. This result can be regarded as evidence for a Mott transition.

The collision-induced reaction of gas-phase atomic hydrogen with chlorine atoms chemisorbed on a silicon (001)-(2×1) surface is studied by use of the classical trajectory approach. The model is based on reaction zone atoms interacting with a finite number of primary system silicon atoms, which are coupled to the heat bath. The potential energy of the H⋯Cl interaction is the primary driver of the reaction, and in all reactive collisions, there is an efficient flow of energy from this interaction to the Cl–Si bond. All reactive events occur in a single impact collision on a subpicosecond scale, following the Eley–Rideal mechanism. These events occur in a localized region around the adatom site on the surface. The reaction probability is dependent upon the gas temperature and largest near 1000 K, but it is essentially independent of the surface temperature. Over the surface temperature range of 0–700 K and gas temperature range of 300 to 2500 K, the reaction probability lies below 0.1. The reaction energy available for the product state is small, and most of this energy is carried away by the desorbing HCl in its translational and vibrational motions. The Langevin equation is used to consider energy exchange between the reaction zone and the surface.

A four-channel impedance measurement system, including a two-channel goniometer, to analyse human arm movement, was constructed. Impedances and joint angles were simultaneously measured for wrist and elbow movements. As the impedance changes resulting from wrist and elbow movements depended heavily on electrode placement, the optimum electrode configurations for those movements were determined by searching for high correlation coefficients, large impedance changes and minimum interferences in ten subjects (age: 29 +/- 6 years). The optimum electrode configurations showed very strong relationships between the wrist joint angle and forearm impedance (correlation coefficient= 0.95 +/- 0.04) and between the elbow joint angle and upper arm impedance (correlation coefficient= -0.97 +/- 0.03). Although the measured impedance changes of the wrist (1.1 +/-1.5 ohms) and elbow (-5.0 +/-2.9 ohms) varied between individuals, the reproducibilities of wrist and elbow impedance changes of five subjects were 5.8 +/- 1.8% and 4.6 +/- 1.4% for the optimum electrode pairs, respectively. It is proposed that this optimum electrode configuration would be useful for future studies involving the accurate measurement of arm movements by the impedance method.