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- Duursma, Allard, et al.
(författare)
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UN Peacekeeping at 75: Achievements, Challenges, and Prospects
- 2023
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Ingår i: International Peacekeeping. - : Taylor & Francis. - 1353-3312 .- 1743-906X. ; 30:4, s. 415-476
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Tidskriftsartikel (refereegranskat)abstract
- This year marks the 75th anniversary of what the UN itself understands to be its first peacekeeping operation. It is therefore an appropriate time to reflect on the track record of UN peacekeeping in its efforts to try to maintain and realize peace and security. Moreover, this milestone invites us to ponder what lies ahead in the realm of peacekeeping. For this reason, this forum article brings together both academics and UN officials to assess the achievements and challenges of UN peacekeeping over the past 75 years. Through a dialogue among peacekeeping scholars and practitioners, we hope to identify current trends and developments in UN peacekeeping, as well as explore priorities for the future to improve the effectiveness of peacekeeping operations in terms of achieving their mandate objectives, such as maintaining peace, protecting civilians, promoting human rights, and facilitating reconciliation. This forum article is structured into six thematic sections, each shedding light on various aspects of UN peacekeeping: (1) foundational principles of UN peacekeeping - namely, consent, impartiality, and the (non-)use of force; (2) protection of civilians; (3) the primacy of politics; (4) early warning; (5) cooperation with regional organizations; and (6) the changing geopolitical landscape in which UN peacekeeping operates.
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- Kourtchev, Ivan, et al.
(författare)
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Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples. Here we resolve this long-standing discrepancy by showing that elevated SOA mass is one of the key drivers of oligomer formation in the ambient atmosphere and laboratory experiments. We show for the first time that a specific organic compound class in aerosols, oligomers, is strongly correlated with cloud condensation nuclei (CCN) activities of SOA particles. These findings might have important implications for future climate scenarios where increased temperatures cause higher biogenic volatile organic compound (VOC) emissions, which in turn lead to higher SOA mass formation and significant changes in SOA composition. Such processes would need to be considered in climate models for a realistic representation of future aerosol-climate-biosphere feedbacks.
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- Lin, Yen-Hung, et al.
(författare)
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A piperidinium salt stabilizes efficient metal-halide perovskite solar cells
- 2020
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Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 369:6499, s. 96-
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Tidskriftsartikel (refereegranskat)abstract
- Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidinium-based ionic compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the bandgap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances the open-circuit voltage and cell efficiency. This additive also retards compositional segregation into impurity phases and pinhole formation in the perovskite absorber layer during aggressive aging. Under full-spectrum simulated sunlight in ambient atmosphere, our unencapsulated and encapsulated cells retain 80 and 95% of their peak and post-burn-in efficiencies for 1010 and 1200 hours at 60 degrees and 85 degrees C, respectively. Our analysis reveals detailed degradation routes that contribute to the failure of aged cells.
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