Stockholm University

About: Stockholm University is a education organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Context (language use). The organization has 21052 authors who have published 62567 publications receiving 2725859 citations. The organization is also known as: University of Stockholm & Stockholms universitet.

Nanocellulose-based foams and aerogels: processing, properties, and applications

Abstract: Nanocellulose is a renewable and biocompatible nanomaterial with a high strength low density and tunable surface chemistry This review summarizes the main processing routes and significant properties of nanocellulose-based foams and aerogels Challenges, such as how to produce long-term stable wet foams or how to avoid structural collapse of the material during solvent removal using eg supercritical drying, are discussed Recent advances in the use of ice templating to generate iso- or anisotropic foams with tunable mechanical and thermal properties are highlighted We illustrate how the porous architecture and properties of nanocellulose-based foams and aerogels can be tailored for applications in eg thermal insulation and energy storage

Measurement of the nucleation of atmospheric aerosol particles

Abstract: The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.

Racemisation in asymmetric synthesis. Dynamic kinetic resolution and related processes in enzyme and metal catalysis

Abstract: Dynamic kinetic resolution (DKR) has recently become not only an alternative to the traditional kinetic resolution, but also a new procedure for asymmetric synthesis. Enzymes are usually the tools to effect this methodology (DKR), although new techniques have emerged through the use of asymmetric transition metal catalysis. All of these methods need two supplementary steps: racemisation together with a consecutive asymmetric transformation. A breakthrough in this area appeared with the powerful combination of enzymatic resolution and transition metal-catalysed racemisation. Thus, new procedures for efficient dynamic kinetic resolution became available. This review covers the concept of dynamic kinetic resolutions emphasizing the most representative examples as well as new developments in this area. Special effort has been made to show the importance of the racemisation step in the whole asymmetric transformation process.

Untangling the Environmentalist's Paradox: Why Is Human Well-being Increasing as Ecosystem Services Degrade?

Abstract: Environmentalists have argued that ecological degradation will lead to declines in the well-being of people dependent on ecosystem services. The Millennium Ecosystem Assessment paradoxically found that human well-being has increased despite large global declines in most ecosystem services. We assess four explanations of these divergent trends: (1) We have measured well-being incorrectly; (2) well-being is dependent on food services, which are increasing, and not on other services that are declining; (3) technology has decoupled well-being from nature; (4) time lags may lead to future declines in well-being. Our findings discount the first hypothesis, but elements of the remaining three appear plausible. Although ecologists have convincingly documented ecological decline, science does not adequately understand the implications of this decline for human well-being. Untangling how human well-being has increased as ecosystem conditions decline is critical to guiding future management of ecosystem services; we propose four research areas to help achieve this goal.