Position-controlled III-V compound semiconductor nanowire solar cells by selective-area metal-organic vapor phase epitaxy

We demonstrate position-controlled III-V semiconductor nanowires (NWs) by using selective-area metal-organic vapor phase epitaxy and their application to solar cells. Efficiency of 4.23% is achieved for InP core-shell NW solar cells. We form a 'flexible NW array' without a substrate, which has the advantage of saving natural resources over conventional thin film photovoltaic devices. Four junction NW solar cells with over 50% efficiency are proposed and discussed.     

Evaluating the Impact of Distance Measures on Deforestation Simulations in the Fluvial Landscapes of Amazonia

Land use and land cover change (LUCC) models frequently employ different accessibility measures as a proxy for human influence on land change processes. Here, we simulate deforestation in Peruvian Amazonia and evaluate different accessibility measures as LUCC model inputs. We demonstrate how the selection, and different combinations, of accessibility measures impact simulation results. Out of the individual measures, time distance to market center catches the essential aspects of accessibility in our study area. The most accurate simulation is achieved when time distance to market center is used in association with distance to transport network and additional landscape variables. Although traditional Euclidean measures result in clearly lower simulation accuracy when used separately, the combination of two complementary Euclidean measures enhances simulation accuracy significantly. Our results highlight the need for site and context sensitive selection of accessibility variables. More sophisticated accessibility measures can potentially improve LUCC models’ spatial accuracy, which often remains low.     

Prospective changes in irrigation water requirements caused by agricultural expansion and climate changes in the eastern arc mountains of Kenya

Water resources and land use are closely linked with each other and with regional climate, assembling a very complex system. The understanding of the interconnecting relations involved in this system is an essential step for elaborating public policies that can effectively lead to the sustainable use of water resources. In this study, an integrated modelling framework was assembled in order to investigate potential impacts of agricultural expansion and climate changes on Irrigation Water Requirements (IWR) in the Taita Hills, Kenya. The framework comprised a land use change simulation model, a reference evapotranspiration model and synthetic precipitation datasets generated through a Monte Carlo simulation. In order to generate plausible climate change scenarios, outputs from General Climate Models were used as reference to perturbing the Monte Carlo simulations. The results indicate that throughout the next 20 years the low availability of arable lands in the hills will drive agricultural expansion to areas with higher IWR in the foothills. If current trends persist, agricultural areas will occupy roughly 60% of the study area by 2030. This expansion will increase by approximately 40% the annual water volume necessary for irrigation. Climate change may slightly decrease crops' IWR in April and November by 2030, while in May a small increase will likely be observed. The integrated assessment of these environmental changes allowed a clear identification of priority regions for land use allocation policies and water resources management.     

Differences in the lethality of occupational accidents in OECD countries

International comparisons of the frequency of occupational accidents are rare because figures reported by each country are influenced by factors other than differences in the occurrence of actual accidents. In this study, we performed an international comparison of occupational accidents which distinguishes between fatal cases and all reported accidents, in order to control for the effects of other factors in accident reporting. Annual data on the numbers of fatal and non-fatal occupational accidents in member countries of the Organisation for Economic Co-operation and Development (OECD) between 1993 and 1998 were obtained from the Labour Statistics Database, which is operated by the International Labour Organization (ILO). The average incidence of all accidents across OECD countries ranged from 17 to 4608 per 100,000 persons in the labor force, whereas the incidence of fatal accidents across OECD countries ranged from 1 to 12 per 100,000 persons in the labor force. Lethality rates per 10,000 total accident cases ranged from 9 (Germany) to 3252 (Turkey). When comparing countries using the same statistical definition of accidents, three or more absence days, the difference in lethality of reported accidents within the same industrial sector is reduced to a sixfold difference (49 for the United Kingdom versus 333 for Ireland). Furthermore, the difference in lethality decreased to about twofold (18 for Spain versus 35 for Czech Republic) in the group using definitions with a criteria of one absent day. The results suggest that reported differences in lethality can reflect artificial administrative factors rather than the harmful factors that cause actual occupational accidents. To make more valid comparison of occupational accident between countries, harmonization of accident statistics is required.     

Improving sustainable recovery of metals from waste printed circuit boards by the primary copper smelter process

In this paper, utilizing the existing primary copper smelter process for the recovery of metals from waste printed circuit boards (PCBs) is proposed as an alternative to the current backyard operations in developing countries. The Model for Evaluating Metal Recycling Efficiency from Complex Scraps (MEMRECS) concept is introduced as a tool for the evaluation of the eco-efficiency of metals recovery from waste PCBs. Based on the MEMRECS approach, the relative contribution of every metal fraction to the recyclability of the whole product is estimated. Thereby, gold content is identified as a key factor strongly influencing the efficiency of metals recovery from waste PCBs. Furthermore, it could be used as an indicator for the categorization of waste PCBs before feeding them into the recycling process. Finally, an integrated process is proposed to optimize the eco-efficiency of metals recovery from waste PCBs in developing countries.     

Concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in blood and breast milk collected from pregnant women in Sapporo City, Japan

We measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (PCBs), and non-dioxin-like PCBs in paired samples of blood and breast milk collected from 67 secundiparas in Sapporo City, Japan, and combined this data with those of the 30 secundiparas previously measured. The arithmetic mean total toxic equivalents (TEQ-WHO) concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk of the 97 secundiparous subjects were 3.0-23 (mean: 13, median: 14) and 2.7-20 (mean: 8.6, median: 8.5) pg TEQ g⁻¹ lipid, respectively. The sums of the concentrations of 56 non-dioxin-like PCB congeners that were measured in the subjects’ blood and breast milk were 16-326 (mean: 107, median: 100) and 12-252 (mean: 73, median: 67) ng g⁻¹ lipid, respectively. The partitioning ratios of individual congeners of PCDDs, PCDFs, dioxin-like PCBs, and non-dioxin-like PCBs from blood to breast milk in secundiparas were almost the same as those of primiparas that have been recently reported, suggesting that the partitioning ratios of these compounds from maternal blood to breast milk in women is little affected by delivery. Furthermore, the partition of PCB congeners with chlorine at the 2-, 3-, 4′-, and 5-positions or the 2-, 4-, 4′-, and 5-positions of the biphenyl ring from the blood to the breast milk tended to occur at a higher level than that of other congeners. In particular, the levels of tetraCB-74 and hexaCB-146 in the breast milk for both primiparous and secundiparous mothers were slightly higher than those in the blood.