Simplifying Nanowire Hall Effect Characterization by Using a Three-Probe Device Design

Electrical characterization of nanowires is a time-consuming and challenging task due to the complexity of single nanowire device fabrication and the difficulty in interpreting the measurements. We present a method to measure Hall effect in nanowires using a three-probe device that is simpler to fabricate than previous four-probe nanowire Hall devices and allows characterization of nanowires with smaller diameter. Extraction of charge carrier concentration from the three-probe measurements using an analytical model is discussed and compared to simulations. The validity of the method is experimentally verified by a comparison between results obtained with the three-probe method and results obtained using four-probe nanowire Hall measurements. In addition, a nanowire with a diameter of only 65 nm is characterized to demonstrate the capabilities of the method. The three-probe Hall effect method offers a relatively fast and simple, yet accurate way to quantify the charge carrier concentration in nanowires and has the potential to become a standard characterization technique for nanowires

Water, Forests, People: The Swedish Experience in Building Resilient Landscapes

A growing world population and rapid expansion of cities increase the pressure on basic resources such as water, food and energy. To safeguard the provision of these resources, restoration and sustainable management of landscapes is pivotal, including sustainable forest and water management. Sustainable forest management includes forest conservation, restoration, forestry and agroforestry practices. Interlinkages between forests and water are fundamental to moderate water budgets, stabilize runoff, reduce erosion and improve biodiversity and water quality. Sweden has gained substantial experience in sustainable forest management in the past century. Through significant restoration efforts, a largely depleted Swedish forest has transformed into a well-managed production forest within a century, leading to sustainable economic growth through the provision of forest products. More recently, ecosystem services are also included in management decisions. Such a transformation depends on broad stakeholder dialog, combined with an enabling institutional and policy environment. Based on seminars and workshops with a wide range of key stakeholders managing Sweden’s forests and waters, this article draws lessons from the history of forest management in Sweden. These lessons are particularly relevant for countries in the Global South that currently experience similar challenges in forest and landscape management. The authors argue that an integrated landscape approach involving a broad array of sectors and stakeholders is needed to achieve sustainable forest and water management. Sustainable landscape management—integrating water, agriculture and forests—is imperative to achieving resilient socio-economic systems and landscapes

Assumption without representation: the unacknowledged abstraction from communities and social goods

We have not clearly acknowledged the abstraction from unpriceable “social goods” (derived from communities) which, different from private and public goods, simply disappear if it is attempted to market them. Separability from markets and economics has not been argued, much less established. Acknowledging communities would reinforce rather than undermine them, and thus facilitate the production of social goods. But it would also help economics by facilitating our understanding of – and response to – financial crises as well as environmental destruction and many social problems, and by reducing the alienation from economics often felt by students and the public

Ion exchangers in analytical chemistry

Mode of access: Internet

Mass Spectrometric Identification' of Aldonolactones as Trimethylsilyl Ethers KLAS ANJOU and ERIK von SYDOW

Trimethylsilyl ethers of aldonolactones are useful for the identification of aldonic acids by mass spectrometry. Peaks recorded for the molecule ion (M) and for mass M-I5 give a reliable determination of the molecular weight. Significant differences exist between 1,4-and I,5-lactones. All diastereomers studied can be well distinguished from each other. I on exchange chromatography has been used for the isolation of aldonic acids from sulfite waste liquors,1,2 from hydrolyzates from oxidized cotton,S and from wood pulps.' With these complex mixtures the separations have to be carried out in several steps to achieve a clean-cut separation. An identification of the isolated acid fractions by classical methods is difficult unless rather large amounts of substances are isolated. The separation process must, therefore, be carried out on a fairly large scale, which is a serious complication in all chromatographic separations of compounds with very similar properties. A combination of various chromatographic methods including gas chromatography has been used for identification 5 but the reliability of such identifications can of course be questioned. The purpose of the present work was to study the application of mass spectrometric identification of aldonic acids. The preparation of trimethylsilyl (TMS) derivatives according to the procedure devised by Sweeley et al.' is a most convenient method for transforming the aldonic acids into volatile compounds suitable for gas-liquid chromatography. Separations of TMSderivatives from various aldonic acids by gas chromatography have also been reported. 6 ,7 As shown in this paper, these derivatives are also suitable for identification by means of mass spectrometry