Influence of skin model on in vitro performance of drug-loaded soluble microneedle arrays

A plethora of studies have described the in vitro assessment of dissolving microneedle (MN) arrays for enhanced transdermal drug delivery, utilising a wide variety of model membranes as a representation of the skin barrier. However, to date, no discussion has taken place with regard to the choice of model skin membrane and the impact this may have on the evaluation of MN performance. In this study, we have, for the first time, critically assessed the most common types of in vitro skin permeation models - a synthetic hydrophobic membrane (Silescol(®) of 75 µm) and neonatal porcine skin of definable thickness (300-350 µm and 700-750 µm) - for evaluating the performance of drug loaded dissolving poly (methyl vinyl ether co maleic acid) (PMVE/MA) MN arrays. It was found that the choice of in vitro skin model had a significant effect on the permeation of a wide range of small hydrophilic molecules released from dissolving MNs. For example, when Silescol(®) was used as the model membrane, the cumulative percentage permeation of methylene blue 24h after the application of dissolvable MNs was found to be only approximately 3.7% of the total methylene blue loaded into the MN device. In comparison, when dermatomed and full thickness neonatal porcine skin were used as a skin model, approximately 67.4% and 47.5% of methylene blue loaded into the MN device was delivered across the skin 24h after the application of MN arrays, respectively. The application of methylene blue loaded MN arrays in a rat model in vivo revealed that the extent of MN-mediated percutaneous delivery achieved was most similar to that predicted from the in vitro investigations employing dermatomed neonatal porcine skin (300-350 µm) as the model skin membrane. On the basis of these results, a wider discussion within the MN community will be necessary to standardise the experimental protocols used for the evaluation and comparison of MN devices.

A Comparison of Programming Models for Multiprocessors with Explicitly Managed Memory Hierarchies

On multiprocessors with explicitly managed memory hierarchies (EMM), software has the responsibility of moving data in and out of fast local memories. This task can be complex and error-prone even for expert programmers. Before we can allow compilers to handle the complexity for us, we must identify the abstractions that are general enough to allow us to write applications with reasonable effort, yet speci?c enough to exploit the vast on-chip memory bandwidth of EMM multi-processors. To this end, we compare two programming models against hand-tuned codes on the STI Cell, paying attention to programmability and performance. The ?rst programming model, Sequoia, abstracts the memory hierarchy as private address spaces, each corresponding to a parallel task. The second, Cellgen, is a new framework which provides OpenMP-like semantics and the abstraction of a shared address spaces divided into private and shared data. We compare three applications programmed using these models against their hand-optimized counterparts in terms of abstractions, programming complexity, and performance.

Performance of Nonlocal Optics When Applied to Plasmonic Nanostructures

Semiclassical nonlocal optics based on the hydrodynamic description of conduction electrons might be an adequate tool to study complex phenomena in the emerging field of nanoplasmonics. With the aim of confirming this idea, we obtain the local and nonlocal optical absorption spectra in a model nanoplasmonic device in which there are spatial gaps between the components at nanometric and subnanometric scales. After a comparison against time-dependent density functional calculations, we conclude that hydrodynamic nonlocal optics provides absorption spectra exhibiting qualitative agreement but not quantitative accuracy. This lack of accuracy, which is manifest even in the limit where induced electric currents are not established between the constituents of the device, is mainly due to the poor description of induced electron densities.

Comparison of adaptive beamforming and orthogonal STBC with outdated feedback

We compare the achievable performance of adaptive beamforming (A-BF) and adaptive orthogonal space time block coding (A-OSTBC) with outdated channel feedback. We extend our single user setup to multiuser diversity systems employing adaptive modulation, and illustrate the impact of feedback delay on the multiuser diversity gain with either A-OSTBC or A-BF. Using closed-form expressions for spectral efficiency and average BER of a multiuser diversity system derived in this paper, we prove that the A-BF scheme outperforms the A-OSTBC scheme with no feedback delay. However, when the feedback delay is large, the A-OSTBC scheme achieves better performance due to the reduced diversity advantage of A-BF. We observe that more transmit antennas bring higher spectral efficiency for BF. With small feedback delay, this becomes inverted using OSTBC, due to the effect of channel-hardening. Interestingly, however, we show that A-OSTBC with multiple users enjoys improved spectral efficiency when the number of transmit antennas is increased and the feedback delay is significant

Comparison of sample preparation methods, validation of an UPLC-MS/MS procedure for the quantification of tetrodotoxin present in marine gastropods and analysis of pufferfish

Tetrodotoxin (TTX) is one of the most potent marine neurotoxins reported. The global distribution of this toxin is spreading with the European Atlantic coastline now being affected. Climate change and increasing pollution have been suggested as underlying causes for this. In the present study, two different sample preparation techniques were used to extract TTX from Trumpet shells and pufferfish samples. Both extraction procedures (accelerated solvent extraction (ASE) and a simple solvent extraction) were shown to provide good recoveries (80-92%). A UPLC-MS/MS method was developed for the analysis of TTX and validated following the guidelines contained in the Commission Decision 2002/657/EC for chemical contaminant analysis. The performance of this procedure was demonstrated to be fit for purpose. This study is the first report on the use of ASE as a mean for TTX extraction, the use of UPLC-MS/MS for TTX analysis, and the validation of this method for TTX in gastropods.

Completeness and timeliness: Cancer registries could/should improve their performance

Cancer registries must provide complete and reliable incidence information with the shortest possible delay for use in studies such as comparability, clustering, cancer in the elderly and adequacy of cancer surveillance. Methods of varying complexity are available to registries for monitoring completeness and timeliness. We wished to know which methods are currently in use among cancer registries, and to compare the results of our findings to those of a survey carried out in 2006.

Methods
In the framework of the EUROCOURSE project, and to prepare cancer registries for participation in the ERA-net scheme, we launched a survey on the methods used to assess completeness, and also on the timeliness and methods of dissemination of results by registries. We sent the questionnaire to all general registries (GCRs) and specialised registries (SCRs) active in Europe and within the European Network of Cancer Registries (ENCR).

Results
With a response rate of 66% among GCRs and 59% among SCRs, we obtained data for analysis from 116 registries with a population coverage of ∼280 million. The most common methods used were comparison of trends (79%) and mortality/incidence ratios (more than 60%). More complex methods were used less commonly: capture–recapture by 30%, flow method by 18% and death certificate notification (DCN) methods with the Ajiki formula by 9%.

The median latency for completion of ascertainment of incidence was 18 months. Additional time required for dissemination was of the order of 3–6 months, depending on the method: print or electronic. One fifth (21%) did not publish results for their own registry but only as a contribution to larger national or international data repositories and publications; this introduced a further delay in the availability of data.

Conclusions
Cancer registries should improve the practice of measuring their completeness regularly and should move from traditional to more quantitative methods. This could also have implications in the timeliness of data publication.

Calculated and observed long term performance of Leneghans embankment

This paper presents the finite element (FE) analysis of the consolidation of the foundation of an embankment constructed over soft clay deposit which shows significant time dependent behaviour and was improved with prefabricated vertical drains. To assess the capability of a simple elastic viscoplastic (EVP) model to predict the long term performance of a geotechnical structure constructed on soft soils, a well documented (Leneghans) embankment was analyzed to predict its long term behaviour characteristics. Two fully coupled two dimensional (2D) plane strain FE analyses have been carried out. In one of these, the foundation of the embankment was modelled with a relatively simpler time dependent EVP model and in the other one, for comparison purposes, the foundation soil was modelled with elasto-plastic Modified Cam-clay (MCC) model. Details of the analyses and the results are discussed in comparison with the field performance. Predictions from the creep (EVP) model were found to be better than those from Elasto-plastic (MCC) analysis. However, the creep analysis requires an additional parameter and additional computational time and resources. © 2011 Taylor & Francis.

Comparison of tack of pressure-sensitive adhesives (PSAs) at different temperatures

Pressure-sensitive adhesives (PSAs) have applications in the fields of packaging, joining, wound care, and personal care. Depending on the application of the PSA, different performance tests are carried out when new products are developed or the quality of the existing products is checked. Tack is the property of an adhesive that enables it to form instant bond on the surface under light pressure. The tack of a PSA strongly depends on the way the bond is created. Parameters such as the bonded area, contact time and the nature of tack materials all affect the tack force measured. In the development of any PSA, it is desirable to correlate the performance related properties such as tack and peel strength to the rheological behaviour. Finding these correlations would make it possible to evaluate the performance of a PSA using its rheological characteristics. In this investigation we have studied the influence of rheological behaviour of three different PSAs on their tackiness. The three different PSAs used in this study are a low molecular weight rosin ester, high molecular weight rosin ester, and dicyclopentadiene. Various rheological properties such as viscosity, phase angle, and elastic and viscous moduli are measured versus the frequency and temperature. Also the tack properties at various removal speeds and temperatures are evaluated. Analysis of the results indicates different performances of the three PSAs which could be related to their rheological properties, especially the phase angle, at different frequencies and temperatures. The PSA with high molecular weight rosin ester is more sensitive to temperature changes and showed drastic changes in tackiness from high temperature to low temperature. On the other hand, rosin ester with low molecular weight is less sensitive to temperature changes. © 2010 VSP.

“I miss being spoon-fed”. A comparison of transition from school to university education from the perspective of undergraduate pharmacy students

Background: The transition from school to university can be challenging and there is increasing concern among academics that students are inadequately prepared for entry to university courses.Aims: To investigate students’ views on transition from school to university education.Method: A focus group was conducted with first-year students and analysed using thematic analysis. Students were invited to participate in an electronic questionnaire; responses were analysed via SPSS for Windows. The Mann– Whitney U test was utilised with p<0.05 set as significant.Results: A response rate of 60% (88/147) was obtained for the questionnaire. Differences included staff-student interactions, learning methods, examination preparation and feedback provision. Many (85%) agreed that the main emphasis in school was on examination preparation; 29.6% considered this to be the case at university (z=-8.315; p<0.05). Most students (95.4%) considered the feedback they received at school helped improve performance; this decreased to 50% when asked about feedback at university (z=-8.326; p<0.05).Conclusion: Students appear to be insufficiently prepared for the demands of higher education. They desire various aspects of their university educational experience to be more akin to that of school, including: a greater level of individual attention, increased access to teaching staff, and further clarification and transparency about the standard required to pass exams. Further work can now be done by academic staff to aid the transition and improve the learning experience.

Is Early Warning Effective for the Improvement of Problem Solving and Project Performance?

Since the first launch of the new engineering contract (NEC) in 1993, early warning of problems has been widely recognized as an important approach of proactive management during a construction or engineering project. Is early warning really effective for the improvement of problem solving and project performance? This is a research question that still lacks a good answer. For this reason, an empirical investigation was made in the United Kingdom (U.K.) to answer the question. This study adopts a combination of literature review, expert interview, and questionnaire survey. Nearly 100 questionnaire responses were collected from the U.K. construction industry, based on which the use of early warning under different forms of contract is compared in this paper. Problem solving and project performance are further compared between the projects using early warning and the projects not using early warning. The comparison provides clear evidence for the significant effect of early warning on problem solving and project performance in terms of time, cost, and quality. Subsequently, an input-process-output model is developed in this paper to explore the relationship among early warning, problem solving, and project
performance. All these help construction researchers and practitioners to better understand the role of early warning in ensuring project success.

Performance Evaluation of Two-Stage Electrokinetic Washing as Soil Remediation Method for Lead Removal using Different Wash Solutions

The study explores the application of a two-stage electrokinetic washing system on remediation of lead (Pb) contaminated soil. The process involved an initial soil washing, followed by an electrokinetic process. The use of electrokinetic process in soil washing not only provided additional driving force for transporting the desorbed Pb away from the soil but also reduced the high usage of wash solution. In this study, the effect of NaNO3, HNO3, citric acid and EDTA as wash solutions on two-stage electrokinetic washing system were evaluated. The results revealed that a two-stage electrokinetic washing process enhanced Pb removal efficiency by 2.52-9.08% and 4.98-20.45% in comparison to a normal electrokinetic process and normal washing process, respectively. Low pH and adequate current were the most important criteria in the removal process as they provided superior desorption and transport properties. The effect of chelating by EDTA was less dominant as it delayed the removal process by forming a transport loop in anode region between Pb ion and complexes. HNO3 was not suitable as wash solution in electrokinetic washing in spite of offering highest removal efficiency as it caused pH fluctuation in the cathode chamber, corroded graphite anode and showed high power consumption. In contrast, citric acid not only yielded high Pb removal efficiency with low power consumption but also maintained a low soil: solution ratio of 1 g: <1 mL, stable pH and electrode integrity. Possible transport mechanisms for Pb under each wash solution are also discussed in this work.

An analysis of stage performance in automotive turbocharger centrifugal compressors

As the concept of engine downsizing becomes ever more integrated into automotive powertrain development strategies, so too does the pressure on turbocharger manufacturers to deliver improvements in map width and a reduction in the mass flow rate at which compressor surge occurs. A consequence of this development is the increasing importance of recirculating flows, both in the impeller inlet and outlet domains, on stage performance.
The current study seeks to evaluate the impact of the inclusion of impeller inlet recirculation on a meanline centrifugal compressor design tool. Using a combination of extensive test data, single passage CFD predictions, and 1-D analysis it is demonstrated how the addition of inlet recirculation modelling impacts upon stage performance close to the surge line. It is also demonstrated that, in its current configuration, the accuracy of the 1-D model prediction diminishes significantly with increasing blade tip speed.
Having ascertained that the existing model requires further work, an evaluation of the vaneless diffuser modelling method currently employed within the existing 1-D model is undertaken. The comparison of the predicted static pressure recovery coefficient with test data demonstrated the inherent inadequacies in the resulting prediction, in terms of both magnitude and variation with flow rate. A simplified alternative method based on an equivalent friction coefficient is also presented that, with further development, could provide a significantly improved stage performance prediction.

Validation of non‑stationary precipitation series for site‑specific impact assessment: comparison of two statistical downscaling techniques

Statistical downscaling (SD) methods have become a popular, low-cost and accessible means of bridging the gap between the coarse spatial resolution at which climate models output climate scenarios and the finer spatial scale at which impact modellers require these scenarios, with various different SD techniques used for a wide range of applications across the world. This paper compares the Generator for Point Climate Change (GPCC) model and the Statistical DownScaling Model (SDSM)—two contrasting SD methods—in terms of their ability to generate precipitation series under non-stationary conditions across ten contrasting global climates. The mean, maximum and a selection of distribution statistics as well as the cumulative frequencies of dry and wet spells for four different temporal resolutions were compared between the models and the observed series for a validation period. Results indicate that both methods can generate daily precipitation series that generally closely mirror observed series for a wide range of non-stationary climates. However, GPCC tends to overestimate higher precipitation amounts, whilst SDSM tends to underestimate these. This infers that GPCC is more likely to overestimate the effects of precipitation on a given impact sector, whilst SDSM is likely to underestimate the effects. GPCC performs better than SDSM in reproducing wet and dry day frequency, which is a key advantage for many impact sectors. Overall, the mixed performance of the two methods illustrates the importance of users performing a thorough validation in order to determine the influence of simulated precipitation on their chosen impact sector.

Performance assessment of cascade control loopswith non-Gaussian disturbances using entropy information

Cascade control is one of the routinely used control strategies in industrial processes because it can dramatically improve the performance of single-loop control, reducing both the maximum deviation and the integral error of the disturbance response. Currently, many control performance assessment methods of cascade control loops are developed based on the assumption that all the disturbances are subject to Gaussian distribution. However, in the practical condition, several disturbance sources occur in the manipulated variable or the upstream exhibits nonlinear behaviors. In this paper, a general and effective index of the performance assessment of the cascade control system subjected to the unknown disturbance distribution is proposed. Like the minimum variance control (MVC) design, the output variances of the primary and the secondary loops are decomposed into a cascade-invariant and a cascade-dependent term, but the estimated ARMA model for the cascade control loop based on the minimum entropy, instead of the minimum mean squares error, is developed for non-Gaussian disturbances. Unlike the MVC index, an innovative control performance index is given based on the information theory and the minimum entropy criterion. The index is informative and in agreement with the expected control knowledge. To elucidate wide applicability and effectiveness of the minimum entropy cascade control index, a simulation problem and a cascade control case of an oil refinery are applied. The comparison with MVC based cascade control is also included.

Assessing 1D Loss Models for the Off-Design Performance Prediction of Automotive Turbocharger Compressors

Single-Zone modelling is used to assess three 1D impeller loss model collections. An automotive turbocharger centrifugal compressor is used for evaluation. The individual 1D losses are presented relative to each other at three tip speeds to provide a visual description of each author’s perception of the relative importance of each loss. The losses are compared with their resulting prediction of pressure ratio and efficiency, which is further compared with test data; upon comparison, a combination of the 1D loss collections is identified as providing the best performance prediction. 3D CFD simulations have also been carried out for the same geometry using a single passage model. A method of extracting 1D losses from CFD is described and utilised to draw further comparisons with the 1D losses. A 1D scroll volute model has been added to the single passage CFD results; good agreement with the test data is achieved. Short-comings in the existing 1D loss models are identified as a result of the comparisons with 3D CFD losses. Further comparisons are drawn between the predicted 1D data, 3D CFD simulation results, and the test data using a nondimensional method to highlight where the current errors exist in the 1D prediction.