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Heath forests which are tropical forests on sandy soils are widely distributed in Borneo and provide many ecosystem services, such as carbon storage and non-timber forest products. Over the past several decades, such forests have been disturbed by non-traditional shifting cultivation, which is usually conducted in unsuitable land with short fallow duration. Anthropogenic disturbances in forests growing on sandy soils that have low nutrient retention capacities may promote further reductions in soil fertility. Long-term monitoring of soil nutrients and biomass accumulation is rare in degraded tropical rainforests growing on sandy soils despite the known negative effects of non-traditional shifting cultivation practices on soil fertility, vegetation and biomass recovery, and the growth of trees planted to rehabilitate forests. The objective of the current study was therefore to elucidate changes in soil fertility and biomass recovery potential in degraded forests on sandy soils in Borneo. We monitored soil nutrients and chemical properties in fifty-four 12 × 12 m plots located on different topographical positions along upper and lower slopes. Samples were collected in plots aged 7 and 14 years after abandonment of shifting cultivation. The biomass of secondary forest trees in all plots 12 years after the abandonment was also measured to determine the relationship between biomass accumulation and changes in soil nutrients. We found that soil pH and cation exchange capacity, and the concentrations of most nutrients, including nitrogen, magnesium, and phosphorus, had decreased significantly 7–14 years after abandonment; biomass accumulation in the plots was also limited 12 years after abandonment (

Poly[p-(methylphenylsilanylene)anthrylene] (PMPSA) which introduced anthracene into the Si–Si backbone structure of poly(methylphenylsilanylene) (PMPS) was synthesized. Schottky barrier photovoltaic cells consisting of semitransparent aluminum and phthalocyanine (H2Pc) dispersed in PMPSA were fabricated (H2Pc-PMPSA). The effects of a binder polymer and annealing of PMPSA on the photovoltaic characteristics were investigated. Since the conductivity of H2Pc-PMPSA composite films increases by the introduction of anthracene and the annealing, the photovoltaic property of H2Pc-PMPSA improves markedly. It is found that the power conversion efficiency becomes a maximum for H2Pc-PMPSA with a copolymerization ratio (1:1) at the annealing temperature of 160°C for 2 h. The photovoltaic parameters have the following values: the power conversion efficiency η is 4.42%, the fill factor F.F. is 0.30, the open circuit voltage V oc is 0.84 V and the short circuit photocurrent J sc is 0.71 µA/cm2. Furthermore, the carrier transport mechanisms of H2Pc-PMPSA composite films are discussed.