Electron dynamics following photoionization: decoherence due to the nuclear-wave-packet width

The advent of attosecond techniques opens up the possibility to observe experimentally electron dynamics following ionization of molecules. Theoretical studies of pure electron dynamics at single fixed nuclear geometries in molecules have demonstrated oscillatory charge migration at a well-defined frequency but often neglecting the natural width of the nuclear wave packet. The effect on electron dynamics of the spatial delocalization of the nuclei is an outstanding question. Here, we show how the inherent distribution of nuclear geometries leads to dephasing. Using a simple analytical model, we demonstrate that the conditions for a long-lived electronic coherence are a narrow nuclear wave packet and almost parallel potential-energy surfaces of the states involved. We demonstrate with numerical simulations the decoherence of electron dynamics for two real molecular systems (paraxylene and polycyclic norbornadiene), which exhibit different decoherence time scales. To represent the quantum distribution of geometries of the nuclear wave packet, the Wigner distribution function is used. The electron dynamics decoherence result has significant implications for the interpretation of attosecond spectroscopy experiments since one no longer expects long-lived oscillations

Coherent mixing of singlet and triplet states in acrolein and ketene: a computational strategy for simulating the electron-nuclear dynamics of intersystem crossing.

We present a theoretical study of intersystem crossing (ISC) in acrolein and ketene with the Ehrenfest method that can describe a superposition of singlet and triplet states. Our simulations illustrate a new mechanistic effect of ISC, namely, that a superposition of singlets and triplets yields nonadiabatic dynamics characteristic of that superposition rather than the constituent state potential energy surfaces. This effect is particularly significant in ketene, where mixing of singlet and triplet states along the approach to a singlet/singlet conical intersection occurs, with the spin-orbit coupling (SOC) remaining small throughout. In both cases, the effects require many recrossings of the singlet/triplet state crossing seam, consistent with the textbook treatment of ISC

Cost-effective bioprocess design for the manufacture of allogeneic CAR-T cell therapies using a decisional tool with multi-attribute decision-making analysis

Reimbursement pressures have resulted in an increased awareness of the importance of estimating and improving manufacturing costs for cell therapy products. This work describes the development and application of a decisional tool capable of computing the manufacturing costs for an allogeneic CAR-T cell bioprocess. The tool was used to facilitate a comparison of the impact on cost of goods (COG) from the use of different process technologies including T-flasks, gas permeable vessels, rocking motion bioreactors, an integrated processing platform, MACS purification and spinning membrane filtration technology. Seven different process flowsheets were compared and the economic drivers of manufacturing costs were analysed. COG per dose values were compared against a specified target selling price (TSP) to understand the feasibility of achieving a target COG as % TSP. Finally, a multi-attribute decision-making (MADM) analysis was conducted in order to allow preference of process design to be determined on the basis of qualitative and quantitative operational attributes, rather than COG alone. The flowsheet containing rocking motion bioreactors, spinning membrane filtration technology and a MACS purification platform was found to result in the lowest COG value. The MADM analysis indicated that this was also the preferred flowsheet when qualitative operational attributes were also considered. Furthermore, process attributes such as viral transduction efficiency and electroporation efficiency were found to be key process economic drivers

Mice null for brush border myosin I assemble brush borders and lack an overt phenotype

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Australia's coastal fisheries and farmed seafood: An ecological basis for determining sustainability

In response to consumer concerns about the sustainability of Australian-sourced seafood we derive a set of criteria within an explicit decision-process that can be used to determine whether locally farmed and wild-caught Australian seafood products meet standards of ecological sustainability and Ecologically Sustainable Development. These criteria substantially address the ecological deficiencies we identified in other systems commonly used for assessing seafood sustainability. The criteria address the issues that are relevant to local seafood production, and are populated with indicators (metrics) and benchmarks relevant to the Australian context. The indicators establish performance thresholds drawn from public domain data about the products, including observed empirical data and proxies, and include default decisions to be applied in the absence of adequate information. This decision structure is set within a peer-reviewed expert jury decision-making process. The criteria, decision process and decision outcomes from assessment of a number of pilot products were tested in a real seafood market (Melbourne), where we found a high level of producer, reseller and consumer acceptance of the judgements and ratings. The use of ecologically-derived standards results in several outcomes that differ from those of other seafood assessment systems, especially those assessments more focused on production standards, such as government, industry and NGO-supported programs, popularly used in Australia and worldwide. We conclude that despite high levels of uncertainty surrounding many of the population parameters, ecological patterns and processes, empirical cost-effective proxies can be used to reasonably estimate a form of sustainability that matches consumer interests/expectations for production of fresh local seafood. Despite the plethora of industry and government programs, there remains a significant but presently unmet consumer demand for ecologically-based, technically robust, independently derived, and readily available information about the local sustainability attributes of Australian wild-caught and farmed fresh seafood

Bunch length measurements using a transverse deflecting cavity on VELA

The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase

In Vitro Primary-Indirect Genotoxicity in Bronchial Epithelial Cells Promoted by Industrially Relevant Few-Layer Graphene

Few-layer graphene (FLG) has garnered much interest owing to applications in hydrogen storage and reinforced nanocomposites. Consequently, these engineered nanomaterials (ENMs) are in high demand, increasing occupational exposure. This investigation seeks to assess the inhalation hazard of industrially relevant FLG engineered with: (i) no surface functional groups (neutral), (ii) amine, and (iii) carboxyl group functionalization. A monoculture of human lung epithelial (16HBE14o-) cells is exposed to each material for 24-h, followed by cytotoxicity and genotoxicity evaluation using relative population doubling (RPD) and the cytokinesis-blocked micronucleus (CBMN) assay, respectively. Neutral-FLG induces the greatest (two-fold) significant increase (p 1 µm diameter). The findings of the present study have demonstrated the capability of neutral-FLG and amine-FLG to induce genotoxicity in 16HBE14o- cells through primary indirect mechanisms, suggesting a possible role for carboxyl groups in scavenging radicals produced via oxidative stress