Radiation effects on beta 10.6 of pure and europium doped KCl

Changes in the optical absorption coefficient as a result of X-ray and electron bombardment of pure KCl (monocrystalline and polycrystalline), and divalent europium doped polycrystalline KCl were determined. The optical absorption coefficients were measured by a constant heat flow calorimetric method. Both 300 KV X-irradiation and 2 MeV electron irradiation produced significant increases in beta 10.6, measured at room temperature. The X-irradiation of pure moncrystalline KCl increased beta 10.6 by 0.005/cm for a 113 MR dose. For an equivalent dose, 2 MeV electrons were found less efficient in changing beta 10.6. However, electron irradiation of pure and Eu-doped polycrystalline KCl produced marked increases in adsorption. Beta increased to over 0.25/cm in Eu-doped material for a 30 x 10 to the 14th power electrons/sq cm dose, a factor of 20 increase over unirradiated material. Moreover, bleaching the electron irradiated doped KCl with 649 m light produced and additional factor of 1.5 increase. These findings will be discussed in light of known defect-center properties in KCl

Benjamin F. Smith Correspondence

Entry is a typed letter on Writers Press Association stationery from William J. Hartford to the Kennebec Public Library, presenting a booklet of an interview with Smith

Origin of the ϕ ∼ ±9° peaks in YBa2Cu3O7−δ films grown on cubic zirconia substrates

The c-axis oriented YBa2Cu3O7−δ films grown on (001) yttria-stabilized cubic zirconia (YSZ) substrates often contain domains whose in-plane alignment is rotated approximately 9° from the cube-on-cube epitaxial relationship, in addition to the more commonly observed 0° and 45° in-plane rotations. We have investigated the origin of this ∼9° orientation using in situ electron diffraction during growth and ex situ 4-circle x-ray diffraction. Our results indicate that the ∼9° orientation provides the most favorable lattice match between the interfacial (110)-oriented BaZrO3 epitaxial reaction layer, which forms between YBa2Cu3O7−δ and the YSZ substrate. If epitaxy occurs directly between YBa2Cu3O7−δ and the YSZ substrate, i.e., before the BaZrO3 epitaxial reaction layer is formed, the 0° and 45° domains have the most favorable lattice match. However, growth conditions that favor the formation of the BaZrO3 reaction layer prior to the nucleation of YBa2Cu3O7−δ lead to an increase in ∼9° domains. The observed phenomenon, which results from epitaxial alignment between the diagonal of a square surface net and the diagonal of a rectangular surface net, is a general method for producing in-plane misorientations, and has also been observed for the heteroepitaxial growth of other materials, including (Ba, K)BiO3/LaAlO3. The YBa2Cu3O7−δ/YSZ case involves epitaxial alignment between [111]BaZrO3 and [110]YSZ, resulting in an expected in-plane rotation of 11.3° to 9.7° for fully commensurate and for fully relaxed (110)BaZrO3 on (001)YSZ, respectivel

Addiction, Autonomy, and the Internet: Some ethical considerations

Despite growing understanding of the addictive qualities of the internet, and rising concerns about the effects of excessive internet use on personal wellbeing and mental health, the corresponding ethical debate is still in its infancy, and many of the relevant philosophical and conceptual frameworks are underdeveloped. Our goal in this chapter is to explore some of this evolving terrain. While there are unique ethical considerations that pertain to the formalisation of a disorder related to excessive internet use, our ethical concerns (and indeed our mental health concerns) about whether certain technologies undermine wellbeing can and should be far broader than the debates about the appropriateness of particular diagnostic categories. In this chapter we introduce some of these wider debates with regards to persuasive digital technologies— particularly those which aim to maximise use, or even to encourage compulsive engagement—as well as the difficulty in articulating the harms involved in excessive internet use, especially where such use has not led to functional impairment. Following these conversations we briefly consider some more practical ethical implications, including regulation of certain design features, concerns about growing socioeconomic inequality in online services, and whether there should be a “right to disconnect.

Attentional Harms and Digital Inequalities

Recent years have seen growing public concern about the effects of persuasive digital technologies on public mental health and well-being. As the draws on our attention reach such staggering scales and as our ability to focus our attention on our own considered ends erodes ever further, the need to understand and articulate what is at stake has become pressing. In this ethical viewpoint, we explore the concept of attentional harms and emphasize their potential seriousness. We further argue that the acknowledgment of these harms has relevance for evolving debates on digital inequalities. An underdiscussed aspect of web-based inequality concerns the persuasions, and even the manipulations, that help to generate sustained attentional loss. These inequalities are poised to grow, and as they do, so will concerns about justice with regard to the psychological and self-regulatory burdens of web-based participation for different internet users. In line with calls for multidimensional approaches to digital inequalities, it is important to recognize these potential harms as well as to empower internet users against them even while expanding high-quality access

Enhancement and Hyperresponsibility

We routinely take diminished capacity as diminishing moral responsibility (as in the case of immaturity, senility, or particular mental impairments). The prospect of enhanced capacity therefore poses immediate questions with regard to moral responsibility. Of particular interest are those capacities that might allow us to better avoid serious harms or wrongdoing. We can consider questions of responsibility with regards to enhancement at various removes. In the first instance: where such (safe and effective) interventions exist, do we have an obligation to undergo such enhancement? Secondly: once enhanced, would the ambit of our responsibility therefore increase? Some philosophers have argued that enhanced capacities potentially generate “hyperresponsibility.” Hyperresponsible people would be held to a different and higher moral standard than those of us with more ordinary human capacities, and are liable to be more blameworthy for wrongdoing than ordinary agents. This chapter discusses the implications of enhancement for three central views of responsibility, namely: capacity-based, control-based and revelation-based views. Debates around moral responsibility have primarily concerned diminished capacities; as such the prospect of enhancement introduces new terrain—and potentially new fault-lines and complexities—in which to interrogate our theoretical conceptions of the foundations (and limits) of moral responsibility

DynGFN: Towards Bayesian Inference of Gene Regulatory Networks with GFlowNets

One of the grand challenges of cell biology is inferring the gene regulatory network (GRN) which describes interactions between genes and their products that control gene expression and cellular function. We can treat this as a causal discovery problem but with two non-standard challenges: (1) regulatory networks are inherently cyclic so we should not model a GRN as a directed acyclic graph (DAG), and (2) observations have significant measurement noise, so for typical sample sizes there will always be a large equivalence class of graphs that are likely given the data, and we want methods that capture this uncertainty. Existing methods either focus on challenge (1), identifying cyclic structure from dynamics, or on challenge (2) learning complex Bayesian posteriors over DAGs, but not both. In this paper we leverage the fact that it is possible to estimate the "velocity" of gene expression with RNA velocity techniques to develop an approach that addresses both challenges. Because we have access to velocity information, we can treat the Bayesian structure learning problem as a problem of sparse identification of a dynamical system, capturing cyclic feedback loops through time. Since our objective is to model uncertainty over discrete structures, we leverage Generative Flow Networks (GFlowNets) to estimate the posterior distribution over the combinatorial space of possible sparse dependencies. Our results indicate that our method learns posteriors that better encapsulate the distributions of cyclic structures compared to counterpart state-of-the-art Bayesian structure learning approaches

Dislocation constriction and cross-slip in Al and Ag: an ab initio study

A novel model based on the Peierls framework of dislocations is developed. The new theory can deal with a dislocation spreading at more than one slip planes. As an example, we study dislocation cross-slip and constriction process of two fcc metals, Al and Ag. The energetic parameters entering the model are determined from ab initio calculations. We find that the screw dislocation in Al can cross-slip spontaneously in contrast with that in Ag, which splits into partials and cannot cross-slip without first being constricted. The dislocation response to an external stress is examined in detail. We determine dislocation constriction energy and critical stress for cross-slip, and from the latter, we estimate the cross-slip energy barrier for the straight screw dislocations

Generalized stacking fault energy surfaces and dislocation properties of aluminum

We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation core properties of aluminum. The generalized stacking fault energy surfaces entering the model are calculated by using first-principles Density Functional Theory (DFT) with pseudopotentials and the embedded atom method (EAM). Various core properties, including the core width, splitting behavior, energetics and Peierls stress for different dislocations have been investigated. The correlation between the core energetics and dislocation character has been explored. Our results reveal a simple relationship between the Peierls stress and the ratio between the core width and atomic spacing. The dependence of the core properties on the two methods for calculating the total energy (DFT vs. EAM) has been examined. The EAM can give gross trends for various dislocation properties but fails to predict the finer core structures, which in turn can affect the Peierls stress significantly (about one order of magnitude).Comment: 25 pages, 12 figure

Development of Novel CO2 Adsorbents for Capture of CO2 from Flue Gas

Capturing CO2 emissions generated from fossil fuel-based power plants has received widespread attention and is considered a vital course of action for CO2 emission abatement. Efforts are underway at the Department of Energy’s National Energy Technology Laboratory to develop viable energy technologies enabling the CO2 capture from large stationary point sources. Solid, immobilized amine sorbents (IAS) formulated by impregnation of liquid amines within porous substrates are reactive towards CO2 and offer an alternative means for cyclic capture of CO2 eliminating, to some degree, inadequacies related to chemical absorption by aqueous alkanolamine solutions. This paper describes synthesis, characterization, and CO2 adsorption properties for IAS materials previously tested to bind and release CO2 and water vapor in a closed loop life support system. Tetraethylenepentamine (TEPA), acrylonitrile-modified tetraethylenepentamine (TEPAN), and a single formulation consisting of TEPAN and N, N’-bis(2-hydroxyethyl)ethylenediamine (BED) were individually supported on a poly (methyl methacrylate) (PMMA) substrate and examined. CO2 adsorption profiles leading to reversible CO2 adsorption capacities were obtained using thermogravimetry. Under 10% CO2 in nitrogen at 25°C and 1 atm, TEPA supported on PMMA over 60 minutes adsorbed ~3.2 mmol/g{sorbent} whereas, TEPAN supported on PMMA along with TEPAN and BED supported on PMMA adsorbed ~1.7 mmol/g{sorbent} and ~2.3 mmol/g{sorbent} respectively. Cyclic experiments with a 1:1 weight ratio of TEPAN and BED supported on poly (methyl methacrylate) beads utilizing a fixed-bed flow system with 9% CO2, 3.5% O2, nitrogen balance with trace gas constituents were studied. CO2 adsorption capacity was ~ 3 mmols CO2/g{sorbent} at 40°C and 1.4 atm. No beneficial effect on IAS performance was found using a moisture-laden flue gas mixture. Tests with 750 ppmv NO in a humidified gas stream revealed negligible NO sorption onto the IAS. A high SO2 concentration resulted in incremental loss in IAS performance and revealed progressive degrees of “staining” upon testing. Adsorption of SO2 by the IAS necessitates upstream removal of SO2 prior to CO2 capture