69,902 research outputs found
Addendum to 'Highly efficient blue photoluminescence from colloidal lead-iodide nanoparticles' [Journal of Physics D. 39 (8) 1477, 2006]
No full textIn a recent paper (Finlayson C E and Sazio P J A 2006 J. Phys. D: Appl. Phys. 39 1477–80) we reported on the properties of colloidal lead (II) iodide nanoparticles, synthesized via a route using coordinating solvents. Our samples were characterized as having highly efficient and photostable photoluminescence in the blue region of the visible spectrum. Subsequent experiments show the observed behaviour of these nanoparticles during nucleation and ripening to be more complicated than originally reported and we believe that the observed photoluminescence may be related to extraneous factors, beyond the experimental methods as previously described
Comment on "Optical characterization of quantum dots entrained in microstructured optical fibers" [Physica E 26 (2005) 377-381]
No full textIn a recent paper, K.E. Meissner, C. Holton, W.B. Spillman Jr. [Physica E 26 (2005) 377] presented a study of the optical properties of colloidal CdSe/ZnS core-shell quantum dots entrained in a microstructured optical fiber. In particular, the authors claimed to have observed optical gain in this system through tight evanescent coupling between a probe light in the core of the fiber and photo-excited quantum dots in the cladding. I suggest that there are fundamental reasons, which are well investigated experimentally and documented, why such quantum dots cannot exhibit optical gain phenomena under continuous-wave excitation, as the authors suggest, and that the experimental results and interpretation do not address these issues, nor do they adequately justify the conclusions reached
Recommended from our members
An 11 600 year-old communal structure from the Neolithic of southern Jordan
Get PDFThe authors present a new type of communal
and monumental structure from the earliest
Neolithic in western Asia. A complement to
the decorated stone pillars erected at G¨obekli
Tepe in the north, ‘Wadi Faynan 16 Structure
O75’ in the southern Levant is a ritualised
gathering place of a different kind. It serves to
define wider western Asia as an arena of social
experiment in the tenth millennium BC, one
in which community seems to take precedence
over economy
Photonic Crystal Photoluminescence modification in Silicon-Rich Silicon Dioxide Waveguides
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The role of implicit wanting in relation to explicit liking and wanting for food : Implications for appetite control
No full textEating is an action open to awareness by the individual; however, it cannot be claimed that processes that control the expression of eating habits are necessarily explicit. This distinction between implicit and explicit processes may enhance understanding of the expression of food reward (particularly the concepts of liking and wanting [Berridge, K. C., & Robinson, T. E. (2003). Parsing reward. Trends in Neurosciences, 26, 507–513] and its importance for human appetite control [Finlayson, G. S., King, N. A., & Blundell, J. E. (2007b). Liking vs. wanting food: Importance for human appetite control and weight regulation. Neuroscience and Biobehavioural Reviews, in press]. The present study investigated the effect of meal-induced satiation on implicit and explicit processes of liking (L) and wanting (W) by developing a computer-based procedure to measure L and W in hungry and satiated states. Explicit measures were derived from analogue ratings whilst an implicit W measure was derived from reaction time in a forced-choice procedure, which also identified food preferences. Seventy subjects (21.8±0.9 years, BMI: 22.2±0.5 kg/m2) completed the procedure before and immediately following consumption of a savoury test meal. Satiation caused explicit ratings of L and W to decrease in all food categories (p<0.01); but with a more marked decrease for savoury foods compared with sweet foods (p<0.01). Implicit W was increased for sweet categories (p<0.01), but not for savoury. Implicit and explicit measures of L and W independently correlated with preference for sweet foods. This study provides support that implicit and explicit processes of food reward can be simultaneously measured and dissociated using a test meal. Adjustments in hunger were linked to changes in explicit L and W in a manner consistent with sensory specific satiety, while a relationship between hunger and implicit W was absent. We suggest that implicit W is not systematically downregulated by the physiological consequences of food consumption in the same way as hunger and therefore may be largely independent of homoeostatic processes influencing intake.\ud
\u
(Data) Solvatochromism based on Structural Color: Smart Polymer Composites for Sensing and Security
No full textData depository for "Solvatochromism based on Structural Color: Smart Polymer Composites for Sensing and Security", by Xu Dong, Pan Wu, Christian G. Schaefer, Liwu Zhang, Chris E. Finlayson, and Changchun Wang.
Paper published in Materials & Design (Elsevier), 201
Memorandum from A. E. Demaray to E. C. Finney
No full textFour letters of correspondence about the purchase of Bright Angel Trail between A. E. Demaray, Acting Director of the Grand Canyon National Park; E. C. Finney, Department of the Interior First Assistant Secretary; Carl T. Hayden, Representative (AZ); and Stephen T. Mather, Director of the National Park Service
Highly efficient blue photoluminescence from colloidal lead-iodide nanoparticles
No full textWe report the synthesis of solvent-stabilized lead-iodide nanoparticles, using a convenient route involving coordinating solvents. The resultant colloids show strong absorption features in the ultraviolet region of the optical spectrum, which are consistent with the formation of semiconducting nanocrystals of lead (II) iodide. An effective-mass approximation model of quantum-confined states is in good agreement with the observed transition energies, giving strong indications of the particle morphologies and dimensions. Intense photoluminescence is also observed, with some spectral tuning possible with ripening time, giving a range of emission photon energies approximately spanning from 2.5 to 3.0 eV. We measure photo-stable luminescence quantum efficiencies of around 20% in solution, increasing to up to 30% if the coordinating ligand is exchanged for a Lewis-base capping layer. This demonstrates the potential for the utilization of lead-iodide nanocrystals in visible optoelectronics applications
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
