116 research outputs found
Working with and for social enterprises: the role of the volunteer ethnographer
Purpose â This paper considers the specific opportunities and challenges of engaging in ethnographic research with organisations in which the researcher participates as a volunteer ethnographer. Design/methodology/approach â The findings in this paper are based on four years of ethnographic research within a social enterprise. Findings â This paper finds that there are significant benefits of the role of the volunteer ethnographer and suggests ways to address some of the challenges. Research limitations/implications â As the field of social enterprise and ethnography grows and researchers engage with methodological discussions about participant observation, the authors suggest that attention should also be paid to the specifics of the role of the volunteer ethnographer. Originality/value â There is growing interest in the use of ethnography in social enterprises. This paper offers unique insight into how this methodology has been applied in the context of self-reliant groups and the importance of the engaging with discussion about the specific role of the volunteer ethnographer
Characterization of tailor-made copolymers of oligo(ethylene glycol) methyl ether methacrylate and N,N-dimethylaminoethyl methacrylate as nonviral gene transfer agents: Influence of macromolecular structure on gene vector particle properties and transfection efficiency.
Chiral Crystal Growth under Grinding
To study the establishment of homochirality observed in the crystal growth
experiment of chiral molecules from a solution under grinding, we extend the
lattice gas model of crystal growth as follows. A lattice site can be occupied
by a chiral molecule in R or S form, or can be empty. Molecules form
homoclusters by nearest neighbor bonds. They change their chirality if they are
isolated monomers in the solution. Grinding is incorporated by cutting and
shafling the system randomly. It is shown that Ostwald ripening without
grinding is extremely slow to select chirality, if possible. Grinding alone
also cannot achieve chirality selection. For the accomplishment of
homochirality, we need an enhanced chirality change on crystalline surface.
With this "autocatalytic effect" and the recycling of monomers due to rinding,
an exponential increase of crystal enantiomeric excess to homochiral state is
realized.Comment: 10 pages, 5 figure
Homochirality and the need of energy
The mechanisms for explaining how a stable asymmetric chemical system can be
formed from a symmetric chemical system, in the absence of any asymmetric
influence other than statistical fluctuations, have been developed during the
last decades, focusing on the non-linear kinetic aspects. Besides the absolute
necessity of self-amplification processes, the importance of energetic aspects
is often underestimated. Going down to the most fundamental aspects, the
distinction between a single object -- that can be intrinsically asymmetric --
and a collection of objects -- whose racemic state is the more stable one --
must be emphasized. A system of strongly interacting objects can be described
as one single object retaining its individuality and a single asymmetry; weakly
or non-interacting objects keep their own individuality, and are prone to
racemize towards the equilibrium state. In the presence of energy fluxes,
systems can be maintained in an asymmetric non-equilibrium steady-state. Such
dynamical systems can retain their asymmetry for times longer than their
racemization time.Comment: 8 pages, 7 figures, submitted to Origins of Life and Evolution of
Biosphere
Speeding up Viedma Deracemization through Water catalyzed and Reactant Selfâcatalyzed Racemization
Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerateâforming chiral compound may principally racemize directly, or via reverse of its formation reaction. For a hydrazine derivative, we investigated available racemization pathways in presence of pyrrolidine or thiourea amine as base catalysts: via Mannich or azaâMichael reaction steps and their reverse, or by enolization. Racemization by enolization was computationally found to dominate, both under waterâfree conditions and in presence of water, involving a multitude of different pathways. Faster racemization in presence of water resulted indeed in more rapid deracemization, when the base was pyrrolidine. Under waterâfree conditions, the role of water as enolization catalyst is assumed by chiral hydrazine itself â in autocatalytic racemization and in which both reactant and product are catalysts
Speeding up Viedma Deracemization through Water-catalyzed and Reactant Self-catalyzed Racemization
Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerate-forming chiral compound may principally racemize directly, or via reverse of its formation reaction. For a hydrazine derivative, we investigated available racemization pathways in presence of pyrrolidine or thiourea amine as base catalysts: via Mannich or aza-Michael reaction steps and their reverse, or by enolization. Racemization by enolization was computationally found to dominate, both under water-free conditions and in presence of water, involving a multitude of different pathways. Faster racemization in presence of water resulted indeed in more rapid deracemization, when the base was pyrrolidine. Under water-free conditions, the role of water as enolization catalyst is assumed by chiral hydrazine itself â in autocatalytic racemization and in which both reactant and product are catalysts
Ăbersetzung und Validierung der Patient Centred Observation Form (PCOF-D) - Grundlage strukturierten Feedbacks zur patientenzentrierten GesprĂ€chsfĂŒhrung in Aus- und Weiterbildung [Bericht ĂŒber Entwicklungsprozess]
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