Polarization-resolved extinction and scattering cross-section of individual gold nanoparticles measured by wide-field microscopy on a large ensemble

We report a simple, rapid, and quantitative wide-field technique to measure the optical extinction $\sigma_{\rm ext}$ and scattering $\sigma_{\rm sca}$ cross-section of single nanoparticles using wide-field microscopy enabling simultaneous acquisition of hundreds of nanoparticles for statistical analysis. As a proof of principle, we measured nominally spherical gold nanoparticles of 40\,nm and 100\,nm diameter and found mean values and standard deviations of $\sigma_{\rm ext}$ and $\sigma_{\rm sca}$ consistent with previous literature. Switching from unpolarized to linearly polarized excitation, we measured $\sigma_{\rm ext}$ as a function of the polarization direction, and used it to characterize the asphericity of the nanoparticles. The method can be implemented cost-effectively on any conventional wide-field microscope and is applicable to any nanoparticles

Wide-field imaging of single nanoparticle extinction with sub-nm2 sensitivity

We report a highly sensitive wide-�eld imaging technique for quantitative measurement of the optical extinction cross-section �ext of single nanoparticles. The technique is simple and high-speed, and enables simultaneous acquisition of hundreds of nanoparticles for statistical analysis. Using rapid referencing, fast acquisition, and a deconvolution analysis, a shot-noise limited sensitivity down to 0.4nm2 is achieved. Measurements on a set of individual gold nanoparticles of 5nm diameter using this method yield �ext = (10:0 � 3:1)nm2, consistent with theoretical expectations, and well above the background uctuations of 0.9nm2

Guidance on Conducting and REporting DElphi Studies (CREDES) in palliative care:Recommendations based on a methodological systematic review

BACKGROUND: The Delphi technique is widely used for the development of guidance in palliative care, having impact on decisions with relevance for patient care. AIM: To systematically examine the application of the Delphi technique for the development of best practice guidelines in palliative care. DESIGN: A methodological systematic review was undertaken using the databases PubMed, CINAHL, Web of Science, Academic Search Complete and EMBASE. DATA SOURCES: Original articles (English language) were included when reporting on empirical studies that had used the Delphi technique to develop guidance for good clinical practice in palliative care. Data extraction included a quality appraisal on the rigour in conduct of the studies and the quality of reporting. RESULTS: A total of 30 empirical studies (1997-2015) were considered for full-text analysis. Considerable differences were identified regarding the rigour of the design and the reporting of essential process and outcome parameters. Furthermore, discrepancies regarding the use of terms for describing the method were observed, for example, concerning the understanding of a 'round' or a 'modified Delphi study'. CONCLUSION: Substantial variation was found concerning the quality of the study conduct and the transparency of reporting of Delphi studies used for the development of best practice guidance in palliative care. Since credibility of the resulting recommendations depends on the rigorous use of the Delphi technique, there is a need for consistency and quality both in the conduct and reporting of studies. To allow a critical appraisal of the methodology and the resulting guidance, a reporting standard for Conducting and REporting of DElphi Studies (CREDES) is proposed

Optical extinction and coherent multiphoton micro-spectroscopy of single nanoparticles

Nanoparticles of many varieties are increasingly studied for use in the physical, chemical, and biological sciences. Metallic nanoparticles exhibit morphology-dependent localised surface plasmon resonances (LSPR), which couple to propagating light, and manifest as a resonant particle polarisability at the LSPR frequency. These resonances can be harnessed for a variety of applications. Many of these applications require characterisation of NP properties, such as their optical response, summarised by the ab- sorption and scattering cross sections. Quantitative measurement of individual NPs is technically difficult, and ensemble measurement techniques, such as absorption spectroscopy, are frequently employed. However, individual NP properties can vary significantly, within the ensemble. In this work, we present a novel, and easy to implement, wide-field extinction microscopy technique, capable of analysing hundreds of nanoparticles simultaneously. Using this technique, we are able to characterise individual gold nanoparticles down to 5 nm diameter, and collate the data to produce ensemble statistics. Furthermore, we developed a program for the rapid analysis of the acquired image, enabling implementation by others in a cost-effective and efficient manner. Using the wide-field extinction technique, we have studied several sizes of gold, platinum, silver, and diamond nanoparticles. We used gold nanoparticles to pro- vide a proof of concept, and found good agreement with the literature. We also present an experimental investigation towards an in-vitro plasmon ruler. Coupled metallic NPs exhibit a LSPR, which is dependent on interparticle distance. The four-wave mixing technique we employ is phase-sensitive, allowing measurement of the shift of the res- onance frequency of gold NPs. To provide proof-of-principle of the plasmon ruler, we correlatively studied gold nanoparticle dimers, with transmission electron microscopy, and four-wave mixing microscopy. In this way, we obtained a direct measure of the interparticle distance, and could relate it to the measured phase shift in four-wave mixing

Sizing individual dielectric nanoparticles with quantitative differential interference contrast microscopy

We report a method to measure the size of single dielectric nanoparticles with high accuracy and precision using quantitative differential interference contrast (DIC) microscopy. Dielectric nanoparticles are detected optically by the conversion of the optical phase change into an intensity change using DIC. Phase images of individual nanoparticles were retrieved from DIC by Wiener filtering, and a quantitative methodology to extract nanoparticle sizes was developed. Using polystyrene beads of 100 nm radius as size standard, we show that the method determines this radius within a few nm accuracy. The smallest detectable polystyrene bead is limited by background and shot-noise, which depend on acquisition and analysis parameters, including the objective numerical aperture, the DIC phase offset, and the refractive index contrast between particles and their surrounding. A sensitivity limit potentially reaching down to 1.8 nm radius was inferred. As application example, individual nanodiamonds with nominal sizes below 50 nm were measured, and were found to have a nearly exponential size distribution with 28 nm mean value. Considering the importance of dielectric nanoparticles in many fields, from naturally occurring virions to polluting nanoplastics, the proposed method could offer a powerful quantitative tool for nanoparticle analysis, combining accuracy, sensitivity and high-throughput with widely available and easy-to-use DIC microscop

Identification of challenges to the availability and accessibility of opioids in twelve European countries:conclusions from two ATOME six-country workshops

Background: Access to many controlled medicines is inadequate in a number of European countries. This leads to deficits in the treatment of moderate to severe pain as well as in opioid agonist therapy. Objective: The study objective was to elaborate the reasons for this inadequacy. The work plan of the Access to Opioid Medication in Europe (ATOME) project included two six-country workshops. These workshops comprised a national situational analysis, drafting tailor-made recommendations for improvement and developing action plans for their implementation. Methods: In total, 84 representatives of the national Ministries of Health, national controlled substances authorities, experts representing regulatory and law enforcement authorities, leading health care professionals, and patient representatives from 13 European countries participated in either one of the workshops. The delegates used breakout sessions to identify key common challenges. Content analysis was used for the evaluation of protocols and field notes. Results: A number of challenges to opioid accessibility in the countries was identified in the domains of knowledge and educational, regulatory, legislative, as well as public awareness and training barriers that limit opioid prescription. In addition, short validity of prescriptions and bureaucratic practices resulting in overregulation impeded availablity of some essential medicines. Stigmatization and criminalisation of people who use drugs remained the major impediment to increasing opioid agonist program coverage. Conclusions: The challenges identified during outcomes of the workshops were used as the basis for subsequent dissemination and implementation activities in the ATOME project, and in some countries the workshop proceedings already served as a stepping-stone for the first changes in regulations and legislation

Building a taxonomy of integrated palliative care initiatives:results from a focus group

Background Empirical evidence suggests that integrated palliative care (IPC) increases the quality of care for palliative patients and supports professional caregivers. Existing IPC initiatives in Europe vary in their design and are hardly comparable. InSuP-C, a European Union research project, aimed to build a taxonomy of IPC initiatives applicable across diseases, healthcare sectors and systems. Methods The taxonomy of IPC initiatives was developed in cooperation with an international and multidisciplinary focus group of 18 experts. Subsequently, a consensus meeting of 10 experts revised a preliminary taxonomy and adopted the final classification system. Results Consisting of eight categories, with two to four items each, the taxonomy covers the process and structure of IPC initiatives. If two items in at least one category apply to an initiative, a minimum level of integration is assumed to have been reached. Categories range from the type of initiative (items: pathway, model or guideline) to patients’ key contact (items: non-pc specialist, pc specialist, general practitioner). Experts recommended the inclusion of two new categories: level of care (items: primary, secondary or tertiary) indicating at which stage palliative care is integrated and primary focus of intervention describing IPC givers’ different roles (items: treating function, advising/consulting or training) in the care process. Conclusions Empirical studies are required to investigate how the taxonomy is used in practice and whether it covers the reality of patients in need of palliative care. The InSuP-C project will test this taxonomy empirically in selected initiatives using IPC