Characterisation of Complex Electrode Processes using Simultaneous Impedance Spectroscopy and Electrochemical Nanogravimetric Measurements.

The methodology and illustrative examples of application are presented for a technique that simultaneously combines electrochemical impedance spectroscopy (EIS) and nanogravimetric measurements; the latter are implemented using a so-called electrochemical quartz crystal nanobalance (EQCN). The combination of EIS and EQCN provides a powerful method for the characterisation of many complex processes at electrochemical interfaces. This method gives in one relatively simple experiment more detailed information than is available from conventional electrochemical techniques.

Multiparametric characterization of nonelectroactive self-assembled monolayers during their formation.

The formation of nonelectroactive self-assembled monolayers (SAMs) at the electrode/electrolyte interface was characterized with simultaneous impedance, gravimetric, and direct current measurements. In the presence of specifically adsorbing inorganic ions, this provides key information about the formation of SAMs. Gravimetric measurements allow an estimation of the adsorbate surface coverage; and completion of the assembly process can then be monitored in real-time.

Theoretical design and experimental implementation of Ag/Au electrodes for the electrochemical reduction of nitrate.

The current imbalance in the biogeochemical cycle of nitrogen is as serious as that of carbon. One way to mitigate this problem is through the electrochemical reduction of nitrates under mild conditions, which is an appealing though not fully understood process. Therefore, deeper insight into the electrocatalytic reaction mechanism is needed to optimize this process.

Electrochemical characterisation of copper thin-film formation on polycrystalline platinum.

Electrochemically formed thin films are vital for a broad range of applications in virtually every field of modern science and technology. Understanding the film formation process could provide a means to aid the characterisation and control of film properties. Herein, we present a fundamental approach that combines two well-established analytical techniques (namely, electrochemical impedance spectroscopy and electrogravimetry) with a theoretical approach to provide physico-chemical information on the electrode/electrolyte interface during film formation.

Towards a detailed in situ characterization of non-stationary electrocatalytic systems.

A complementary combination of cyclic voltammetry, impedance spectroscopy and quartz crystal microbalance techniques was used to: (i) control the assembly of a model electrocatalytic system consisting of monolayer and sub-monolayer amounts of Ag and Pb on a Au electrode, (ii) evaluate the system performance for the reduction of NO(3)(-) and (iii) study the disassembly of the electrocatalytic system to explore any changes which occurred during the assembly and/or catalytic stages. Physical models of the electrochemical interface (described in terms of equivalent electric circuits) at all stages are found to be considerably different but consistent with each other. Deposition of the Ag atomic layer on Au is accompanied by spontaneous surface alloying and specific adsorption of anions.

Specific indolo[3,2,1-jk]carbazole conducting thin-film materials production by selective substitution.

Selectively substituted indolo[3,2,1-jk] carbazole (IC) molecules have been synthesized through flash vacuum pyrolysis (FVP) and then electro-oxidized, resulting in the formation of redox-active and electronically conducting thin films consisting exclusively of three highly luminescent dimer species, the 2,2'-, 2,10'-, and 10,10'-coupled dimers. DFT calculation has enabled both the accurate calculation of monomer oxidation potentials and the prediction of the nature of the resulting dimers through consideration of the coupling of the oxidized monomer radical cations. This demonstrates that substituted ICs represent a class of molecules able to form redox-active and conducting dimer films of controlled composition upon oxidation and that DFT calculations can be used to inform the synthesis of specific IC monomers most likely to both produce electronically conducting thin-film materials and yield specific luminescent dimers with desirable materials properties.

The formation and characterisation of redox active and luminescent materials from the electrooxidation of indolizine.

Indolizine has been synthesised on the small scale with enhanced yield using a novel Flash Vacuum Pyrolysis method. Electrooxidation of indolizine results in the formation of a redox-active film on the electrode surface. Excellent agreement is found between calculated and experimental indolizine oxidation potentials; a combination of fluorescence and electrochemical studies are consistent with the computational prediction that electroxidation results in the formation of three specific and redox active indolizine dimers.

Fluorescence enhancement by symmetry breaking in a twisted triphenylene derivative.

1,4,5,8,9,12-hexamethyltriphenylene (HMTP) shows a high photoluminescence quantum yield (PLQY) of 31% in the solid state, making it of interest for luminescence applications. The detailed photophysical properties of HMTP have been investigated by using time-resolved and steady-state luminescence, PLQY, and molar absorption coefficient measurements. An enhancement of the transition dipole moment for fluorescence and absorption was demonstrated compared to the case of unsubstituted triphenylene, which resulted in a 20-fold increase in the radiative decay rate.

Cross-sectional study of the prevalence of radiographic degenerative joint disease in domesticated cats.

Objective: To determine the prevalence of radiographic signs of degenerative joint disease (DJD) in a randomly selected sample of domestic cats.

Study Design: Prospective observational study.

Animals: Client-owned cats.

Synthesis of novel 2,5-diarylselenophenes from selenation of 1,4-diarylbutane-1,4-diones or methanol/arylacetylenes.

Reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide [PhP(Se)(mu-Se)](2) (Woollins' reagent, WR) with one equivalent of 1,4-diarylbutane-1,4-diones 1a-g in refluxing toluene affords the corresponding 2,5-diarylselenophenes 2a-g in excellent yields (up to 99%). Alternatively, the 2,5-diarylselenophenes (2a and 2b) can be obtained in 70-80% yields from the reaction of arylacetylene with an equivalent of O-methyl Se-hydrogen phenylphosphonodiselenoate; the latter was derived from WR and methanol. The first X-ray structure of 2,5-diarylselenophenes is presented along with characterisation of their redox properties.

Calculation of the redox properties of aromatics and prediction of their coupling mechanism and oligomer redox properties.

The B3LYP density functional theory method has been used to determine theoretical values for the peak oxidation potentials for a range of redox-active aromatics in acetonitrile at room temperature. Excellent agreement to within 37 mV is found between these values and those observed experimentally. The calculated electron spin density distributions of indole monomer and indole oligomer radical cations also enable a plausible mechanism to be advanced by which the experimentally observed asymmetric trimer product is formed.

The production and characterisation of novel conducting redox-active oligomeric thin films from electrooxidised indolo[3,2,1-jk]carbazole.

Indolo[3,2,1-jk]carbazole (IC) has been synthesised on a gram scale by flash vacuum pyrolysis. In contrast to a previous suggestion, IC is planar and it is also highly fluorescent, with a solution quantum yield of 0.41.

1,4,5,8,9,12-Hexamethyltriphenylene. A molecule with a flipping twist.

The synthesis and characterization of 1,4,5,8,9,12-hexamethyltriphenylene (5) is described. In the solid state, X-ray crystallographic studies reveal that compound 5 presents a highly distorted C2 geometry with a 53 degrees end-to-end twist. In solution, variable-temperature 1H NMR studies and molecular modeling present a story of rapid dynamic conformational interconversions between two C2 enantiomers (with a low activation barrier) and a slower C2-D3 interconversion (with a relatively high barrier)--the first time clear evidence of conformational interchange for these hindered triphenylenes has been provided.

Dual triggering of DNA binding and fluorescence via photoactivation of a dinuclear ruthenium(II) arene complex.

The dinuclear RuII arene complexes [{(eta6-arene)RuCl}2(mu-2,3-dpp)](PF6)2, arene=indan (1), benzene (2), p-cymene (3), or hexamethylbenzene (4) and 2,3-dpp=2,3-bis(2-pyridyl)pyrazine, have been synthesized and characterized. Upon irradiation with UVA light, complexes 1 and 2 readily underwent arene loss, while complexes 3 and 4 did not. The photochemistry of 1 was studied in detail.

Mean arterial pressure and systolic blood pressure for detection of hypotension during hemapheresis: implications for patients with baseline hypertension.

Mean arterial pressure (MAP) has been characterized as a more sensitive and physiologically appropriate hemodynamic parameter in the detection of hemapheresis-related hypotension, resulting in a much closer correlation with the presence of symptomatic hypotension. Patients were enrolled over a 12-month period and data collected on any previous diagnosis of hypertension, antihypertensive therapy used, indication for apheresis, age decile, and gender. Baseline vital signs, any hypotensive signs or symptoms observed, and the patient's vital signs at the time of any hypotensive episode were recorded.

Febrile nonhemolytic transfusion reactions. Management by premedication and cost implications in adult patients.

Context: Febrile nonhemolytic transfusion reactions (FNHTRs) cause unwelcome interruptions during the course of blood product transfusions and necessitate measures to verify the nature of the reaction and to exclude certain dangerous reactions, such as hemolytic and septic phenomena.

Objective: To examine transfusion medicine data to determine the clinical implications of the routine administration of antipyretic medication to adult patients before transfusion for the prevention of FNHTRs.

Design: A retrospective review was conducted of FNHTR data during 5 years (1998-2002), and a determination was made of the cost of a transfusion complicated by an FNHTR.

A new HLA-A1 mutation: a novel, null variant allele.

From an unusually informative family of 8 with near identical parental haplotypes (a and c), which differed by a single nucleotide substitution, we identified a new HLA-A1 null variant. While serologic antigen typing initially showed a "blank" allele in maternal haplotype "c" and 2 male offspring, more sophisticated DNA molecular HLA typing subsequently revealed the presence of a novel HLA-A0101 allele. Sequence-based typing showed a point mutation consisting of a nucleotide substitution of a cytosine for a guanine at nucleotide 215 yielding an amino acid change of arginine to proline at codon 48 in exon 2 (R48P).

Comprehensive graphic-based display of clinical pathology laboratory data.

In this age of ever-increasing demands for and uses of patient data, technologic advancements in the form of electronic patient records permit improved data access and prompt retrieval of higher quality patient care data, with more versatility in display, facilitating the integration of information concerning patients over time and between settings of care, which is in turn more accessible for use by practitioners and provides more efficient and effective decision support in areas of patient care. The graphic display of laboratory data is central to the evolving computerized patient record and needs to be taken into careful consideration along with clinician perception and ease of data interpretation in redesigning the graphic reporting of numeric clinical pathology laboratory data. An ideal system should generate user-friendly, graphic-based comprehensive reports highlighting abnormalities with trends for diagnosis, clinical management, and risk-factor detection.

Mean arterial pressure (MAP): an alternative and preferable measurement to systolic blood pressure (SBP) in patients for hypotension detection during hemapheresis.

Current protocols utilize systolic blood pressure (SBP) of less than 80 mmHg as objective evidence of hypotension during hemapheresis. However, tissue hypoperfusion is the pathophysiologic endpoint of low blood pressure, and mean arterial pressure (MAP), rather than SBP, is the physiologic driving force behind blood flow to organs and tissues. It is thus hypothesized that MAP is more appropriate than SBP in the assessment of hypotension and that a threshold MAP can be utilized as a sensitive indicator of hypotension during hemapheresis.