Patterns of Data Analysis\ulcorner

Unwin, Antony The Korean Statistical Society 2001 Journal of the Korean Statistical Society Vol.30 No.2

How do you carry out data analysis\ulcorner There are few texts and little theory. One approach could be to use a pattern language, an idea which has been successful in field as diverse as town planning and software engineering. Patterns for data analysis are defined and discussed, illustrated with examples.

PTEROSAURS FROM ASIA

( David M . Unwin,Natasha N . Bakhurina,Martin G . Lockley,Makoto Manabe,Jun Chang Lu ) 한국고생물학회 1997 N/A Vol.2 No.-

Response to the Comments on ‘Point of Care D-Dimer Testing in the Emergency Department–A Bioequivalence Study’ and Erratum to the Results

Shuhana Perveen,Danielle Unwin,Amith L Shetty,Karen Byth 대한진단검사의학회 2014 Annals of Laboratory Medicine Vol.34 No.1

We have read with interest the comments made on our study ti- tled ‘Point of care (POC) D-dimer testing in the Emergency de- partment–a bioequivalence study’ [1]. Ekelund and Heilmann, referring to the results and conclu- sions of the study, have suggested that one of the discrepancies may be caused by a typographical error, and this inference prob- ably stems from the use of the term ‘range’ in the published arti- cle. This should have been termed ‘Bland-Altman limits of agree- ment’ (0.24-2.13) for all the cases where both tests were ordered and not just for the 8 POC-negative VIDAS (VIDAS D-dimer as- say; bioMérieux SA, RCS Lyon, France)-positive patients. The data have been reconfirmed by our database as not being a re- porting error.

Point of Care D-Dimer Testing in the Emergency Department: A Bioequivalence Study

Shuhana Perveen,Danielle Unwin,Amith Loknath Shetty 대한진단검사의학회 2013 Annals of Laboratory Medicine Vol.33 No.1

Background: D-dimer is used widely as a diagnostic aid in low- and moderate-risk patients with suspected venous thromboembolism (VTE). While our laboratory utilizes VIDAS D-dimer analyzer (bioMérieux SA, France), our emergency department (ED) recently procured a D-dimer analyzer AQT90 FLEX (Radiometer Medical ApS, Denmark) for point of care testing (POCT) to facilitate patient management. We aimed to determine whether the time taken to receive D-dimer results using the 2 different analyzers differed significantly and to quantify the limits of agreement between the results of the 2 methods measured on the same patient. Methods: Adult patients presenting to the ED and requiring diagnostic workup for suspected VTE were included in this prospective observational study. Patients underwent simultaneous D-dimer measurements using the 2 different analyzers. Results: The paired results from 104 patients were analyzed. The median time for the Ddimer results from triage by VIDAS was 258 min (Inter-quartile range [IQR], 173-360) and by POCT was 146 min (IQR, 55-280.5); the median time difference was 101.5 min (IQR, 82-125.5). On an average, POCT D-dimer values were 15% lower on the same sample (limits of agreement, 34-213%). POCT predicted 83% of VIDAS positive results (sensitivity, 83.3%[95% confidence interval (CI), 70.4-91.3%]; specificity, 100% [95% CI, 93.6-100%]). All patients with positive imaging were identified correctly by both methods. Conclusions: POCT delivers D-dimer results in significantly shorter turnaround times than pathology services; however, poor bioequivalence between VIDAS and POCT raises the issue of acceptability for use in the ED.

Nanoscale Electrocatalysis of Hydrazine Electro-Oxidation at Blistered Graphite Electrodes

E, Sharel P.,Kim, Yang-Rae,Perry, David,Bentley, Cameron L.,Unwin, Patrick R. American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.44

<P>There is great interest in finding and developing new, efficient, and more active electrocatalytic materials. Surface modification of highly oriented pyrolytic graphite, through the introduction of surface 'blisters', is demonstrated to result in an electrode material with greatly enhanced electrochemical activity. The increased electrochemical activity of these blisters, which are produced by electro-oxidation in HClO4, is revealed through the use of scanning electrochemical cell microscopy (SECCM), coupled with complementary techniques (optical microscopy, field emission scanning electron microscopy, Raman spectroscopy, and atomic force microscopy). The use of a linear sweep voltammetry (LSV)-SECCM scan regime allows for dynamic electrochemical mapping, where a voltammogram is produced at each pixel, from which movies consisting of spatial electrochemical currents, at a series of applied potentials, are produced. The measurements reveal significantly enhanced electrocatalytic activity at blisters when compared to the basal planes, with a significant cathodic shift in the onset potential of the hydrazine electro-oxidation reaction. The improved electrochemical activity of the hollow structure of blistered graphite could be explained by the increased adsorption of protonated hydrazine at oxygenated defect sites, the ease of ion solvent intercalation/deintercalation, and the reduced susceptibility to N-2 nanobubble attachment (as a product of the reaction). This study highlights the capability of electrochemistry to tailor the surface structure of graphite and presents a new electrocatalyst for hydrazine electro-oxidation.</P>

Redox-Dependent Spatially Resolved Electrochemistry at Graphene and Graphite Step Edges

Gü,ell, Aleix G.,Cuharuc, Anatolii S.,Kim, Yang-Rae,Zhang, Guohui,Tan, Sze-yin,Ebejer, Neil,Unwin, Patrick R. American Chemical Society 2015 ACS NANO Vol.9 No.4

<P>The electrochemical (EC) behavior of mechanically exfoliated graphene and highly oriented pyrolytic graphite (HOPG) is studied at high spatial resolution in aqueous solutions using Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP> as a redox probe whose standard potential sits close to the intrinsic Fermi level of graphene and graphite. When scanning electrochemical cell microscopy (SECCM) data are coupled with that from complementary techniques (AFM, micro-Raman) applied to the same sample area, different time-dependent EC activity between the basal planes and step edges is revealed. In contrast, other redox couples (ferrocene derivatives) whose potential is further removed from the intrinsic Fermi level of graphene and graphite show uniform and high activity (close to diffusion-control). Macroscopic voltammetric measurements in different environments reveal that the time-dependent behavior after HOPG cleavage, peculiar to Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP>, is not associated particularly with any surface contaminants but is reasonably attributed to the spontaneous delamination of the HOPG with time to create partially coupled graphene layers, further supported by conductive AFM measurements. This process has a major impact on the density of states of graphene and graphite edges, particularly at the intrinsic Fermi level to which Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP> is most sensitive. Through the use of an improved voltammetric mode of SECCM, we produce movies of potential-resolved and spatially resolved HOPG activity, revealing how enhanced activity at step edges is a subtle effect for Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP>. These latter studies allow us to propose a microscopic model to interpret the EC response of graphene (basal plane and edges) and aged HOPG considering the nontrivial electronic band structure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-4/acsnano.5b00550/production/images/medium/nn-2015-00550c_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b00550'>ACS Electronic Supporting Info</A></P>

Impact of Surface Chemistry on Nanoparticle–Electrode Interactions in the Electrochemical Detection of Nanoparticle Collisions

Chen, Chang-Hui,Ravenhill, Emma R.,Momotenko, Dmitry,Kim, Yang-Rae,Lai, Stanley C. S.,Unwin, Patrick R. American Chemical Society 2015 Langmuir Vol.31 No.43

<P>The electrochemical detection of a single nanoparticle (NP) at a support electrode can provide key information on surface chemistry and fundamental electron transfer (ET) properties at the nanoscale. This study employs scanning electrochemical cell microscopy (SECCM) as a fluidic device to both deliver individual citrate-capped gold nanoparticles (AuNPs) and study the interactions between them and a range of alkanethiol-modified Au electrodes with different terminal groups, namely, −COOH, −OH, and −CH<SUB>3</SUB>. Single NP collisions were detected through the AuNP-mediated ET reaction of Fe(CN)<SUB>6</SUB><SUP>4–/3–</SUP> in aqueous solution. The collision frequency, residence time, and current–time characteristics of AuNPs are greatly affected by the terminal groups of the alkanethiol. Methods to determine these parameters, including the effect of the instrument response function, and derive ET kinetics are outlined. To further understand the interactions of AuNPs with these surfaces, atomic force microscopy (AFM) force measurements were performed using citrate-modified Au-coated AFM tips and the same alkanethiol-modified Au substrates in aqueous solution at the same potential bias as for the AuNP collision experiments. Force curves on OH-terminated surfaces showed no repulsion and negligible adhesion force. In contrast, a clear repulsion (on approach) was seen for COOH-terminated surface and adhesion forces (on retract) were observed for both COOH- and CH<SUB>3</SUB>-terminated surfaces. These interactions help to explain the residence times and collision frequencies in AuNP collisions. More generally, as the interfacial properties probed by AFM appear to be amplified in NP collision experiments, and new features also become evident, it is suggested that such experiments provide a new means of probing surface chemistry at the nanoscale.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2015/langd5.2015.31.issue-43/acs.langmuir.5b03033/production/images/medium/la-2015-03033w_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la5b03033'>ACS Electronic Supporting Info</A></P>

Nucleation and Aggregative Growth of Palladium Nanoparticles on Carbon Electrodes: Experiment and Kinetic Model

Kim, Yang-Rae,Lai, Stanley C. S.,McKelvey, Kim,Zhang, Guohui,Perry, David,Miller, Thomas S.,Unwin, Patrick R. American Chemical Society 2015 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.119 No.30

<P>The mechanism and kinetics of the electrochemical nucleation and growth of palladium (Pd) nanoparticles (NPs) on carbon electrodes have been investigated using a microscale meniscus cell on both highly oriented pyrolytic graphite (HOPG) and a carbon-coated transmission electron microscopy (TEM) grid. Using a microscale meniscus cell, it is possible to monitor the initial stage of electrodeposition electrochemically, while the ability to measure directly on a TEM grid allows subsequent high-resolution microscopy characterization which provides detailed nanoscopic and kinetic information. TEM analysis clearly shows that Pd is electrodeposited in the form of NPs (approximately 1–2 nm diameter) that aggregate into extensive nanocrystal-type structures. This gives rise to a high NP density. This mechanism is shown to be consistent with double potential step chronoamperometry measurements on HOPG, where a forward step generates electrodeposited Pd and the reverse step oxidizes the surface of the electrodeposited Pd to Pd oxide. The charge passed in these transients can be used to estimate the amounts of NPs electrodeposited and their size. Good agreement is found between the electrochemically determined parameters and the microscopy measurements. A model for electrodeposition based on the nucleation of NPs that aggregate to form stable structures is proposed that is used to analyze data and extract kinetics. This simple model reveals considerable information on the NP nucleation rate, the importance of aggregation in the deposition process, and quantitative values for the aggregation rate.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-30/acs.jpcc.5b03513/production/images/medium/jp-2015-03513y_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b03513'>ACS Electronic Supporting Info</A></P>

Time-Resolved Detection and Analysis of Single Nanoparticle Electrocatalytic Impacts

Kang, Minkyung,Perry, David,Kim, Yang-Rae,Colburn, Alex W.,Lazenby, Robert A.,Unwin, Patrick R. American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.34

<P>There is considerable interest in understanding the interaction and activity of single entities, such as (electro)catalytic nanoparticles (NPs), with (electrode) surfaces. Through the use of a high bandwidth, high signal/noise measurement system, NP impacts on an electrode surface are detected and analyzed in unprecedented detail, revealing considerable new mechanistic information on the process. Taking the electrocatalytic oxidation of H<SUB>2</SUB>O<SUB>2</SUB> at ruthenium oxide (RuO<SUB><I>x</I></SUB>) NPs as an example, the rise time of current–time transients for NP impacts is consistent with a hydrodynamic trapping model for the arrival of a NP with a distance-dependent NP diffusion-coefficient. NP release from the electrode appears to be aided by propulsion from the electrocatalytic reaction at the NP. High-frequency NP impacts, orders of magnitude larger than can be accounted for by a single pass diffusive flux of NPs, are observed that indicate the repetitive trapping and release of an individual NP that has not been previously recognized. The experiments and models described could readily be applied to other systems and serve as a powerful platform for detailed analysis of NP impacts.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2015/jacsat.2015.137.issue-34/jacs.5b05856/production/images/medium/ja-2015-05856p_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja5b05856'>ACS Electronic Supporting Info</A></P>

FIRST REPORT OF PTEROSAUR TRACKS FROM ASIA , CHULLANAM PROVINCE , KOREA

( Martin G . Lockley,Min Huh,Seong Kyu Lim,Seong Young Yang,Seung Soo Chun,David M . Unwin ) 한국고생물학회 1997 N/A Vol.2 No.-