London-van der Waals adhesiveness of rough particles

Van der Waals forces often dominate interactions and adhesion between fine particles and, in turn, decisively influence the bulk behaviour of powders. However, so far there is no effective means to characterize the adhesive behaviour of such particles. A complication is that most powder particles have rough surfaces, and it is the asperities on the surfaces that touch, confounding the actual surface that is in contact. Conventional approaches using surface energy provide limited information regarding adhesion, and pull-off forces measured through atomic force microscope (AFM) are highly variable and difficult to interpret. In this paper we develop a model which combines the Rumpf-Rabinovich and the JKR-DMT theories to account simultaneously for the effects of surface roughness and deformation on adhesion. This is applied to a 'characteristic asperity' which may be easily obtained from AFM measurements. The concept of adhesiveness, a material property reflecting the influences of elastic deformability, surface roughness, and interfacial surface energy, is introduced as an efficient and quantitative measure of the adhering tendency of a powder. Furthermore, a novel concept of specific adhesiveness is proposed as a convenient tool for characterizing and benchmarking solid materials. This paper provides an example to illustrate the use of the proposed theories. (c) 2005 Elsevier B.V. All rights reserved.

OMERACT-OARSI Initiative: Osteoarthritis Research Society International set of responder criteria for osteoarthritis clinical trials revisited.

Background: The OARSI Standing Committee for Clinical Trials Response Criteria Initiative had developed two sets of responder criteria to present the results of changes after treatment in three symptomatic domains (pain, function, and patient's global assessment) as a single variable for clinical trials (1). For each domain, a response was defined by both a relative and an absolute change, with different cut-offs with regard to the drug, the route of administration and the OA localization. Objective: To propose a simplified set of responder criteria with a similar cut-off, whatever the drug, the route or the OA localization. Methods: Data driven approach: (1) Two databases were considered The 'elaboration' database with which the formal OARSI sets of responder criteria were elaborated and The 'revisit' database. (2) Six different scenarios were evaluated: The two formal OARSI sets of criteria Four proposed scenarios of simplified sets of criteria Data from clinical randomized blinded placebo controlled trials were used to evaluate the performances of the two formal scenarios with two different databases ('elaboration' versus 'revisit') and those of the four proposed simplified scenarios within the 'revisit' database. The placebo effect, active effect, treatment effect, and the required sample arm size to obtain the placebo effect and the active treatment effect observed were the performances evaluated for each of the six scenarios. Experts' opinion approach: Results were discussed among the participants of the OMERACT VI meeting, who voted to select the definite OMERACT-OARSI set of criteria (one of the six evaluated scenarios). Results: Data driven approach: Fourteen trials totaling 1886 CA patients and fifteen studies involving 8164 CA patients were evaluated in the 'elaboration' and the 'revisit' databases respectively. The variability of the performances observed in the 'revisit' database when using the different simplified scenarios was similar to that observed between the two databases ('elaboration' versus 'revisit') when using the formal scenarios. The treatment effect and the required sample arm size were similar for each set of criteria. Experts' opinion approach: According to the experts, these two previous performances were the most important of an optimal set of responder criteria. They chose the set of criteria considering both pain and function as evaluation domain and requiring an absolute change and a relative change from baseline to define a response, with similar cut-offs whatever the drug, the route of administration or the CA localization. Conclusion: This data driven and experts' opinion approach is the basis for proposing an optimal simplified set of responder criteria for CA clinical trials. Other studies, using other sets of CA patients, are required in order to further validate this proposed OMERACT - OARSI set of criteria. (C) 2004 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Automated Analysis of the Auditory Brainstem Response Using Derivative Estimation Wavelets

In this paper, we describe an algorithm that automatically detects and labels peaks I - VII of the normal, suprathreshold auditory brainstem response (ABR). The algorithm proceeds in three stages, with the option of a fourth: ( 1) all candidate peaks and troughs in the ABR waveform are identified using zero crossings of the first derivative, ( 2) peaks I - VII are identified from these candidate peaks based on their latency and morphology, ( 3) if required, peaks II and IV are identified as points of inflection using zero crossings of the second derivative and ( 4) interpeak troughs are identified before peak latencies and amplitudes are measured. The performance of the algorithm was estimated on a set of 240 normal ABR waveforms recorded using a stimulus intensity of 90 dBnHL. When compared to an expert audiologist, the algorithm correctly identified the major ABR peaks ( I, III and V) in 96 - 98% of the waveforms and the minor ABR peaks ( II, IV, VI and VII) in 45 - 83% of waveforms. Whilst peak II was correctly identified in only 83% and peak IV in 77% of waveforms, it was shown that 5% of the peak II identifications and 31% of the peak IV identifications came as a direct result of allowing these peaks to be found as points of inflection. Copyright (C) 2005 S. Karger AG, Basel.

Relationship of extent and nature of dysfunctional myocardium to brain natriuretic peptide in patients with ischemic left ventricular dysfunction

We studied the relationship between brain natriuretic peptide (BNP) levels and viable myocardium and ischemic myocardium, regional scar and regional contractile function. Fifty-nine patients underwent dobutamine echocardiography and magnetic resonance imaging and resting BNP levels were determined. By magnetic resonance imaging, total extent of dysfunctional myocardium correlated strongest with BNP (r = 0.60, p < 0.0001). The extent of scar, viability and ischemia also correlated. At dobutamine echocardiography, a composite of dysfunctional and ischemic myocardium was the strongest correlate of BNP (r = 0.48, p < 0.0001), with less strong correlations by global parameters. The extent of dysfunctional myocardium, rather than its nature determines BNP levels.

Electrostatically mediated specific adsorption of small molecules in metallo-organic frameworks

We investigate the interaction of ethylene and ethane with a Cu-tricarboxylate complex and show that at low loadings the lighter molecule has a higher binding energy as a result of an increased interaction with the framework Cu and stronger hydrogen bonding with the basic framework oxygens. This leads to selective adsorption of ethylene by a factor of about 2 at low pressure, which is overcome by the stronger van der Waals interaction of ethane at high loadings, explaining recent literature data. The results suggest the possibility of separation of light hydrocarbons at low pressures or in trace amounts.