On the origin of multihole oxygen evolution in haematite photoanodes

The oxygen evolution reaction (OER) plays a crucial role in (photo)electrochemical devices that use renewable energy to produce synthetic fuels. Recent measurements on semiconducting oxides have found a power law dependence of the OER rate on surface hole density, suggesting a multihole mechanism. In this study, using transient photocurrent measurements, density functional theory simulations and microkinetic modelling, we have uncovered the origin of this behaviour in haematite. We show here that the OER rate has a third-order dependence on the surface hole density. We propose a mechanism wherein the reaction proceeds by accumulating oxidizing equivalents through a sequence of one-electron oxidations of surface hydroxy groups. The key O–O bond formation step occurs by the dissociative chemisorption of a hydroxide ion involving three oxyl sites. At variance with the case of metallic oxides, the activation energy of this step is weakly dependent on the surface hole coverage, leading to the observed power law

Simulating and delineating future land change trajectories across Europe

Explorations of future land use change are important to understand potential conflicts between competing land uses, trade-offs associated with particular land change trajectories, and the effectiveness of policies to steer land systems into desirable states. Most model-based explorations and scenario studies focused on conversions in broad land use classes, but disregarded changes in land management or focused on individual sectors only. Using the European Union (EU) as a case study, we developed an approach to identifying typical combinations of land cover and management changes by combining the results of multimodel simulations in the agriculture and forest sectors for four scenarios from 2000 to 2040. We visualized land change trajectories by mapping regional hotspots of change. Land change trajectories differed in extent and spatial pattern across the EU and among scenarios, indicating trajectory-specific option spaces for alternative land system outcomes. In spite of the large variation in the area of change, similar hotspots of land change were observed among the scenarios. All scenarios indicate a stronger polarization of land use in Europe, with a loss of multifunctional landscapes. We analyzed locations subject to change by comparing location characteristics associated with certain land change trajectories. Results indicate differences in the location conditions of different land change trajectories, with diverging impacts on ecosystem service provisioning. Policy and planning for future land use needs to account for the spatial variation of land change trajectories to achieve both overarching and location-specific targets

STUDI KROMOSOM TANAMAN MATA KUCING (Dimocarpus malesianus Leenh.) DALAM UPAYA PENINGKATAN KUALITAS BUAH

Tanaman mata kucing (Dimocarpus malesianus) merupakan tanaman yang dimanfaatkan buahnya. Buah tersebut memiliki rasa yang manis, biasanya dimakan dalam keadaan segar. Ketika musim berbuah, buah mata kucing diperdagangkan di wilayah Pulau Kalimantan. Nama mata kucing digunakan karena isi buah dan bijinya mirip dengan mata kucing yang bersinar. Pustaka yang ada, belum ada penelitian yang melaporkan jumlah kromosom dan susunan genetik tentang tanaman mata kucing secara akurat. Pengetahuan tentang informasi genetik tanaman mata kucing sebagai usaha perbaikan kualitas tanaman tersebut melalui kegiatan pemuliaan. Studi kromosom tanaman mata kucing merupakan aspek penting yang dapat berkontribusi sebagai dasar pemuliaan tanaman tersebut. Penelitian ini dilaksanakan di Laboratorium Fisiologi dan Bioteknologi Tanaman Fakultas Pertanian Universitas Sebelas Maret Surakarta mulai Mei 2010 sampai dengan Maret 2011. Penelitian ini menggunakan metode squashing, dengan pra-perlakuan aquades selama ± 24 jam dalam referigator 50 C, fiksasi dengan larutan asam asetat 45 % dalam suhu ruang selama ± 1 jam, dan hidrolisis menggunakan HCl 1N dalam suhu ruang selama ± 5 menit, serta pewarnaan dalam larutan aceto orcein 2% selama 24 jam dalam suhu referigator 50 C. Pengamatan dilakukan dengan mikroskop cahaya terhadap sejumlah sel-sel yang menunjukkan penyebaran kromosom secara baik, difoto serta dibua