112 research outputs found

    Action spectroscopy of gas-phase carboxylate anions by multiple photon IR electron detachment/attachment

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    We report on a form of gas-phase anion action spectroscopy based on infrared multiple photon electron detachment and subsequent capture of the free electrons by a neutral electron scavenger in a Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. This method allows one to obtain background-free spectra of strongly bound anions, for which no dissociation channels are observed. The first gas-phase spectra of acetate and propionate are presented using SF6 as electron scavenger and a free electron laser as source of intense and tunable infrared radiation. To validate the method, we compare infrared spectra obtained through multiple photon electron detachment/attachment and multiple photon dissociation for the benzoate anion. In addition, different electron acceptors are used, comparing both associative and dissociative electron capture. The relative energies of dissociation (by CO2 loss) and electron detachment are investigated for all three anions by DFT and CCSD(T) methods. DFT calculations are also employed to predict vibrational frequencies, which provide a good fit to the infrared spectra observed. The frequencies of the symmetric and antisymmetric carboxylate stretching modes for the aliphatic carboxylates are compared to those previously observed in condensed-phase IR spectra and to those reported for gas-phase benzoate, showing a strong influence of the solution environment and a slight substituent effect on the antisymmetric stretch.Comment: Revised version, Submitted to J Phys Chem

    Failure to report as a breach of moral and professional expectation

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    Cases of poor care have been documented across the world. Contrary to professional requirements, evidence indicates that these sometimes go unaddressed. For patients the outcomes of this inaction are invariably negative. Previous work has either focused on why poor care occurs and what might be done to prevent it, or on the reasons why those who are witness to it find it difficult to raise their concerns. Here we build on this work but specifically foreground the responsibilities of registrants and students who witness poor care. Acknowledging the challenges associated with raising concerns, we make the case that failure to address poor care is a breach of moral expectation, professional requirement and sometimes, legal frameworks. We argue that reporting will be more likely to take place if those who wish to enter the profession have a realistic view of the challenges they may encounter. When nurses are provided with robust and applied education on ethics, when ‘real-world’ cases and exemplars are used in practice and when steps are taken to develop and encourage individual moral courage, we may begin to see positive change. Ultimately however, significant change is only likely to take place where practice cultures invite and welcome feedback, promote critical reflection, and where strong, clear leadership support is shown by those in positions of influence across organisations

    Scanning tunneling microscopy and atomic force microscopy in the characterization of activated graphite electrodes

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    Sir: To date there have been many methods described to activate carbon electrodes, including electrochemical treatment (1-1 7), laser irradiation (18-21), radio-frequency (RF) plasma (22), and heat treatment (23-26). These methods were developed empirically, and only now is an understanding of parameters controlling surface activity beginning to emerge (20,27). Electrochemical treatment and laser irradiation are particularly attractive treatments because they are relatively inexpensive, are quick, and can be performed without removing the electrode from solution. Activation, common to these procedures, may be attributable to an increase in the exposed edge plane density, which has been associated with faster kinetics (14,20). Copper deposition in conjunction with scanning electron microscopy (SEM) has shown an increase in the density of localized defects on active surfaces (15); an increase in surface activity is associated with an increase in the density of the localized defects (15). Scanning tunneling microscopy (STM), phase detection microscopy, and SEM have also been used to study the effects of electrochemical treatment of highly oriented pyrolytic graphite (HOPG) (13) and glassy carbon (GC) (16,17). These studies have suggested an increase in surface roughness consistent with an increase in the density of exposed edge planes

    Developing a fuzzy multi-criteria decision-making model for selecting design-build operational variations

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    Many academic researchers have conducted studies on the selection of design-build (DB) delivery method; however, there are few studies on the selection of DB operational variations, which poses challenges to many clients. The selection of DB operational variation is a multi-criteria decision making process that requires clients to objectively evaluate the performance of each DB operational variation with reference to the selection criteria. This evaluation process is often characterized by subjectivity and uncertainty. In order to resolve this deficiency, the current investigation aimed to establish a fuzzy multicriteria decision-making (FMCDM) model for selecting the most suitable DB operational variation. A three-round Delphi questionnaire survey was conducted to identify the selection criteria and their relative importance. A fuzzy set theory approach, namely the modified horizontal approach with the bisector error method, was applied to establish the fuzzy membership functions, which enables clients to perform quantitative calculations on the performance of each DB operational variation. The FMCDM was developed using the weighted mean method to aggregate the overall performance of DB operational variations with regard to the selection criteria. The proposed FMCDM model enables clients to perform quantitative calculations in a fuzzy decision-making environment and provides a useful tool to cope with different project attributes
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