Etching characteristics of nondoped GaN films with the polar surface in KOH solution have been investigated. It is confirmed that the continuous etching in KOH solution takes place only for the GaN films with N-face (Ϫc) polarity independent of the deposition method and growth condition. It is found by x-ray photoelectron spectroscopy ͑XPS͒ analysis for the Ga face (ϩc) and N-face (Ϫc) GaN films that the atomic composition of the ϩc surface is not changed before and after dipping in KOH solution and that on the other hand, the amount of oxygen ͑oxide͒ on the Ϫc surface is significantly decreased by the etching. It is also found that the band bending increases by Ϫ0.4Ϯ0.2 and 0.6Ϯ0.2 eV for the ϩc and Ϫc surfaces after etching, respectively. This is discussed in terms of the surface chemistry. Based on the XPS result, the selective etching of the GaN polar surface is pointed out to originate from bonding configuration of nitrogen at the surface.

(+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (4, LY354740), a highly selective and orally active group II metabotropic glutamate receptor (mGluR) agonist, has increased interest in the study of group II mGluRs. Our interest focused on a conformationally constrained form of compound 4, because it appeared that the rigid form resulted in not only selectivity for group II mGluR but was orally active. Therefore, we introduced a fluorine atom to compound 4, based on the molecular size (close resemblance to hydrogen atom) and electronegativity (effects on the electron distribution in the molecule) of this atom and carbon-fluorine bond energy. Compound (+)-7 (MGS0008), the best compound among 3-fluoro derivatives 7-10, retained the agonist activity of compound 4 for mGluR2 and mGluR3 ((+)-7: EC(50) = 29.4 +/- 3.3 nM and 45.4 +/- 8.4 nM for mGluR2 and mGluR3, respectively; 4: EC(50) = 18.3 +/- 1.6 nM and 62.8 +/- 12 nM for mGluR2 and mGluR3, respectively) and increased the oral activity of compound 4 ((+)-7: ED(50) = 5.1 mg/kg and 0.26 mg/kg for phencyclidine (PCP)-induced hyperactivity and PCP-induced head-weaving behavior, respectively; 4: ED(50) = >100 mg/kg and 3.0 mg/kg for PCP-induced hyperactivity and PCP-induced head-weaving behavior, respectively). In addition, a compound [(3)H]-(+)-7 binding study using mGluR2 or 3 expressed in CHO cells was successful ((+)-7: K(i) = 47.7 +/- 17 nM and 65.9 +/- 7.1 nM for mGluR2 and mGluR3, respectively; 4: K(i) = 23.4 +/- 7.1 nM and 53.5 +/- 13 nM for mGluR2 and mGluR3, respectively). On the basis of a successful result of compound 7, we focused on the introduction of a fluorine atom on the C6 position of compound 4. (1R,2S,5R, 6R)-2-amino-6-fluorobicyclo[3.1.0]hexane-2,6-dicarboxylic acid ((-)-11) exhibited a high degree of agonist activity for group II mGluRs equal to that of compound 4 or 7 ((-)-11: K(i) = 16.6 +/- 5.6 and 80.9 +/- 31 nM for mGluR2 and mGluR3, respectively). Our interest shifted to modification on CH(2) at C4 position of compound 11, since replacement of the CH(2) group with either an oxygen atom or sulfur atom yielded compound 5 or 6, resulting in increased agonist activity. We selected a carbonyl group instead of CH(2) at the C4 position of compound 11. The carbonyl group might slightly change the relative conformation of three functional groups, the amino group and two carboxylic acids, which have important roles in mediating the interaction between group II mGluRs and their ligand, compared with the CH(2) group of 4, oxygen atom of 5, and sulfur atom of 6. (1R,2S,5S,6S)-2-Amino-6-fluoro-4-oxobicyclo[3.1. 0]hexane-2,6-dicarboxylic acid monohydrate ((+)-14, MGS0028) exhibited a remarkably high degree of agonist activity for mGluR2 (K(i) = 0.570 +/- 0.10 nM) and mGluR3 (K(i) = 2.07 +/- 0.40 nM) expressed in CHO cells but not mGluR4, 6, 7, 1a, or 5 expressed in CHO cells (K(i) = >100 000 nM). Furthermore, compound (+)-14 strongly inhibited phencyclidine (PCP)-induced head-weaving behavior (ED(50) = 0.090 microg/kg) and hyperactivity (ED(50) = 0.30 ...

Background The International Classification of Functioning, Disability and Health (ICF) is a conceptual framework and classification system by the World Health Organization (WHO) to understand functioning. The objective of this discussion paper is to offer a conceptual definition for vocational rehabilitation (VR) based on the ICF. Method We presented the ICF as a model for application in VR and the rationale for the integration of the ICF. We also briefly reviewed other work disability models. Results Five essential elements of foci were found towards a conceptual definition of VR: an engagement or re-engagement to work, along a work continuum, involved health conditions or events leading to work disability, patient-centered and evidence-based, and is multi-professional or multidisciplinary.Conclusions VR refers to a multi-professional approach that is provided to individuals of working age with health-related impairments, limitations, or restrictions with work functioning and whose primary aim is to optimize work participation. We propose that the ICF and VR interface be explored further using empirical and qualitative works and encouraging stakeholders' participation.