A combined approach of electronic structure calculations and spectroscopy for elucidating reaction mechanisms in organic and bioinorganic systems

This thesis describes the use of density functional theory (DFT) to assist the interpretation of advanced spectroscopic techniques such as stopped flow Fourier transform infrared spectroscopy (FTIR), muon spin resonance (�SR), and nuclear inelastic scattering (NIS). These complementary techniques are used to investigate the structure and mechanism of a variety of important chemical systems, some of which are relevant to biological energy transduction and energy harvesting. The mechanisms by which [FeFe] and [NiFe] hydrogenase enzymes catalyse the reversible reduction of protons to dihydrogen are of intrinsic interest in the context of a developing hydrogen technology for energy transduction. Gas phase DFT calculations are used to simulate and assign structure to experimental solution phase FTIR spectra for a family of [FeFe]-hydrogenase model complexes. Further, the Mulliken charge distribution across the Fe centres are compared for di�erent dithiolate bridge groups and PMe3 ligand positions. In the pursuit of understanding the protonation mechanism of [FeFe]-hydrogenases, transition state theory is used and the energetics of reaction pathways leading to terminal and bridging hydrides calculated and compared. NIS demonstrates great potential for characterising the [FeFe]-hydrogenase mimics. In order to further develop and validate the technique, a combination of NIS, DFT calculations, FTIR and Raman spectroscopies are applied to a small Fe(III) model system in order to provide complete a characterisation of the low frequency meta

The platform conjuncture

The paper engages the problematic of platform capitalism in the company of Fernand Braudel. Platform capitalism is accordingly located in the opaque zone of the so-called antimarket, “where the great predators roam,” with its characteristic conditions of monopolization, concentrated economic and political power, and cultures of systematic regulatory evasion. The Braudelian schema requires that platform capitalism is situated, both historically and geographically, in this case both as a distinctive conjunctural moment and as an epiphenomenon of variegated and globalizing processes of financialization and neoliberalization. The paper offers an antidote to the mainstream treatment of platforms, with its technological exuberance, its preoccupation with internally generated dynamics, and its exaggerated claims to novelty and indeed revolutionary significance. Thinking conjuncturally about platform capitalism qua Braudelian capitalism does not just counter these problems, it represents a constructive supplement to extant political-economy accounts. It accentuates and problematizes non-repeating historical continuities (against presumptions of a radical technological-organizational break). And it points to constitutive conditions of coexistence (against the imaginary of a separate, self-propelling, and distinct innovation economy). To pose the platform question along with Braudel is to begin with problematics of monopoly power and antimarket behavior, rather than with technological affordances, network capacities, or the market

Reanimating Neoliberalism: Process Geographies of Neoliberalisation

Artykuł stanowi bezpośrednią odpowiedź na wcześniejsze głosy w debacie na temat historyczności państwa neoliberalnego. Mierząc się z propozycjami Loïca Wacquanta i Mathieu Hilgersa, autorzy uzupełniają je o lekceważony, nie tylko w tym przypadku, wymiar przestrzenności. Zabieg ten pozwala na traktowanie neoliberalizacji, odróżnionej od bardziej statycznego i nade wszystko dyskursywnego konceptu neoliberalizmu, jako wielobarwnego i uzależnionego od kontekstu (społecznego, geograficznego, politycznego itp.) procesu. Proponowana tu „reanimacja” neoliberalizmu ma na uwadze uchwycenie go w ruchu i w zróżnicowanych odmianach, w przeciwieństwie do ujednoliconej wizji nieuchronnie jednokierunkowego (i prowadzącego do wycofania państwa) projektu neoliberalnej restrukturyzacji. Ogląd tak niejednoznacznej rzeczywistości umożliwia, zdaniem autorów, metodologiczna droga pośrednia, która wiedzie ich „pomiędzy paradygmatycznymi miejscami prawdy [truth spots] oraz przestrzeniami wyjątku, w kierunku zrozumienia złożonej przestrzenności faktycznie istniejącego neoliberalizmu oraz jego koewolucji z doktrynami neoliberalnymi”

Effect of the mycotoxin, ochratoxin A, on hormone-stimulated ion transport in a cultured cell model of the renal principal cell

The mycotoxin ochratoxin A (OTA) is a common contaminant of many foodstuffs and, consequently, is present in a large proportion of tested populations of humans and commercial animals. The predominant effects of OTA are manifested in the kidney where the severity varies from salt wasting to renal carcinoma formation in a concentration-dependent fashion. The MDCK-C7 renal cell culture model responds to various hormones known to regulate electrolyte and fluid balance and was used as a model to study the chronic effects of an acute exposure to low dose OTA. The natriferic hormones aldosterone and insulin-like growth factor 1 (IGF1) both stimulate Na(+) flux in a reabsorptive direction via activation of the epithelial Na(+) channel (ENaC). In contrast, anti-diuretic hormone (ADH) stimulates three separate and temporally distinct ion transport responses, one of which is Na(+) reabsorption. Treatment of MDCK-C7 cells with OTA (100 nM) for 48 h selectively and irreversibly inhibits hormone-stimulated Na(+) reabsorption via ENaC. This effect was retained for 48 cell passages after the removal of the toxin and mimics the OTA-induced salt-wasting that has been documented in clinical studies. These studies indicate that the effect of the toxin is genomic and therefore, likely to be long lasting in exposed animals and humans

Rate of molecular transfer of allyl alcohol across an AOT surfactant layer using muon spin spectroscopy

The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of Transverse Field muon spin rotation (TF- μSR), Avoided Level Crossing muon spin resonance (ALC-μSR) and Monte Carlo simulations. Reverse microemulsions consist of nanometer sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, µSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulphosuccinate (Aerosol OT), with allyl alcohol (CH2=CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte-Carlo calculations of the ΔM=0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 109 s-1, placing the rate of interfacial transfer at the diffusion limit

Hybrid silicon nanostructures with conductive ligands and their microscopic conductivities

Silicon nanoparticles (SiNPs) functionalized with conjugated molecules promise a potential pathway to generate a new category of thermoelectric materials. While the thermoelectric performance of materials based on phenyl-acetylene capped SiNPs has been proven, their low conductivity is still a problem for their general application. A muon study of phenyl-acetylene capped SiNPs has been recently carried out using the HiFi spectrometer at the Rutherford Appleton Laboratory, measuring the ALC spectra as a function of temperature. The results show a reduction in the measured line width of the resonance above room temperature, suggesting an activated behaviour for this system. This study shows that the muon study could be a powerful method to investigate microscopic conductivity of hybrid thermoelectric materials

The political economy of Public Employment Services: measurement and disempowered empowerment?

Active Labour Market Policies (ALMPs) and Public Employment Services (PES) are related components of the European Union and member state labour market policy. Typically, PES are analysed in terms of a narrow concern with efficiency and effectiveness of service. In this paper, we argue that PES are constituents in broader processes. They are not just means to facilitate employment, they are also part of transmission mechanisms for a political economy of competitiveness. They play a particular role in governance processes, and so serve to produce and reproduce power relations that are intrinsic to those processes. We argue that the technical ways that PES have been managed over recent decades has contributed to broader processes of disempowering labour, through depoliticized management practices. We argue that attempts at even limited re-empowerment of labour would require a repoliticization of these management practices

Feminist Reflections on the Scope of Labour Law: Domestic Work, Social Reproduction and Jurisdiction

Drawing on feminist labour law and political economy literature, I argue that it is crucial to interrogate the personal and territorial scope of labour. After discussing the “commodification” of care, global care chains, and body work, I claim that the territorial scope of labour law must be expanded beyond that nation state to include transnational processes. I use the idea of social reproduction both to illustrate and to examine some of the recurring regulatory dilemmas that plague labour markets. I argue that unpaid care and domestic work performed in the household, typically by women, troubles the personal scope of labour law. I use the example of this specific type of personal service relation to illustrate my claim that the jurisdiction of labour law is historical and contingent, rather than conceptual and universal. I conclude by identifying some of the implications of redrawing the territorial and personal scope of labour law in light of feminist understandings of social reproduction