Image decomposition and uncertainty quantification for the assessment of manufacturing tolerances in stress analysis

This article presents a methodology for the treatment of uncertainty in nonlinear, interference-fit, stress analysis problems arising from manufacturing tolerances. Image decomposition is applied to the uncertain stress field to produce a small number of shape descriptors that allow for variability in the location of high-stress points when geometric parameters (dimensions) are changed within tolerance ranges. A meta-model, in this case based on the polynomial chaos expansion, is trained using a full finite element model to provide a mapping from input geometric parameters to output shape descriptors. Global sensitivity analysis using Sobol’s indices provides a design tool that enables the influence of each input parameter on the observed variances of the outputs to be quantified. The methodology is illustrated by a simplified practical design problem in the manufacture of automotive wheels

Mechanistic Study of the Conductance and Enhanced Single-Molecule Detection in a Polymer–Electrolyte Nanopore

Solid-state nanopores have been widely employed in the detection of biomolecules, but low signal-to-noise ratios still represent a major obstacle in the discrimination of nucleic acid and protein sequences substantially smaller than the nanopore diameter. The addition of 50% poly(ethylene) glycol (PEG) to the external solution is a simple way to enhance the detection of such biomolecules. Here, we demonstrate with finite-element modeling and experiments that the addition of PEG to the external solution introduces a strong imbalance in the transport properties of cations and anions, drastically affecting the current response of the nanopore. We further show that the strong asymmetric current response is due to a polarity-dependent ion distribution and transport at the nanopipette tip region, leading to either ion depletion or enrichment for few tens of nanometers across its aperture. We provide evidence that a combination of the decreased/increased diffusion coefficients of cations/anions in the bath outside the nanopore and the interaction between a translocating molecule and the nanopore–bath interface is responsible for the increase in the translocation signals. We expect this new mechanism to contribute to further developments in nanopore sensing by suggesting that tuning the diffusion coefficients of ions could enhance the sensitivity of the system

Probing RNA Conformations Using a Polymer–Electrolyte Solid-State Nanopore

Nanopore systems have emerged as a leading platform for the analysis of biomolecular complexes with single-molecule resolution. The conformation of biomolecules, such as RNA, is highly dependent on the electrolyte composition, but solid-state nanopore systems often require high salt concentration to operate, precluding analysis of macromolecular conformations under physiologically relevant conditions. Here, we report the implementation of a polymer–electrolyte solid-state nanopore system based on alkali metal halide salts dissolved in 50% w/v poly(ethylene) glycol (PEG) to augment the performance of our system. We show that polymer–electrolyte bath governs the translocation dynamics of the analyte which correlates with the physical properties of the salt used in the bath. This allowed us to identify CsBr as the optimal salt to complement PEG to generate the largest signal enhancement. Harnessing the effects of the polymer–electrolyte, we probed the conformations of the Chikungunya virus (CHIKV) RNA genome fragments under physiologically relevant conditions. Our system was able to fingerprint CHIKV RNA fragments ranging from ∼300 to ∼2000 nt length and subsequently distinguish conformations between the co-transcriptionally folded and the natively refolded ∼2000 nt CHIKV RNA. We envision that the polymer–electrolyte solid-state nanopore system will further enable structural and conformational analyses of individual biomolecules under physiologically relevant conditions

The ESA "Plasma Laboratory in Space" study

The European Space Agency has initiated, in the context of its General Studies Programme, a study of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by “space plasma physics”. A team of experts has been set-up to review a broad range of area including industrial plasma physics and pure plasma physics, astrophysical and solar-terrestrial areas. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on spatial scale (102 to104 m) intermediate between what is achievable on ground experiment and usual solar system plasma observations

Plasma kinetics issues in an ESA study for a plasma laboratory in space

A study supported by the European Space Agency (ESA), in the context of its General Studies Programme, performed an investigation of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by ‘space plasma physics’. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on a spatial scale (101–104 m) intermediate between what is achievable on the ground and the usual solar system plasma observations. Detailed feasibility studies have been performed for three experiments: active magnetic experiments, largescale discharges and long tether–plasma interactions. The perspectives opened by these experiments are discussed for magnetic reconnection, instabilities, MHD turbulence, atomic excited states kinetics, weakly ionized plasmas,plasma diagnostics, artificial auroras and atmospheric studies. The discussion is also supported by results of numerical simulations and estimates

Data for "Mechanistic Study of the Conductance and Enhanced Single-Molecule Detection in a Polymer Electrolyte Nanopore"

The data set contains all relevant ionic current traces and voltammetric data recorded using pClamp system for the associated paper entitled: 'Mechanistic Study of the Conductance and Enhanced Single-Molecule Detection in a Polymer Electrolyte Nanopore'. The data is in the native pClamp format of abf files. Analysis routine can be performed with script that relies on abf files. The data set is aim to allow users to re-analysis the data and to reproduce the observations made in the associated publication

Nocturnal obstructive respiratory events severity is associated with low parental quality

Objective: Despite of the large prevalence of obstructive sleep apnea syndrome (OSAS) in pediatric age, numerous aspects of its impact on day life and on parental quality are still poor studied and considered in the clinical management. The study evaluated the stress levels and copying styles in a large sample of mother of children with OSAS. Method: 374 mothers of children affected by OSAS (mOSAS) were compared with a group of mothers of 421 neurotypical healthy children (mTDC) for stress perceived stress levels and for coping strategies. Subjects were recruited from Italian Regions in Sicily, Campania, Calabria and Umbria. Results: Among both groups mOSAS and mTDC no differences were reported for children age (p=0.340), children gender (p=0.956), similarly for age of mothers (p=0.188). Discussion: The perceived stress assessment in mOSAS showed higher rate of all parental stress scores of PSI-SF: Parental Distress domain (p<0.001), Difficult Child subscale (p<0.001), Parent-Child Dysfunctional Interaction domain (p<0.001) and Total Stress subscale score (p <0.001) than mTDC. Regarding the CISS evaluation, mOSAS reported higher scores in emotion-oriented (p<0.001) and avoidance-oriented (p <0.001) scales, while low task-oriented coping style scale score was reported (p<0.001) than mTDC. Pearson’s correlation analysis showed significant values for AHI, ODI and mdes SpO2 for each scale of PSI-SF questionnaire, particularly relevant for P-CDI (p<0.001), DC (p<0.001) and Stress Tot (p<0.001). Conclusion: Pediatric OSAS tends to cause maternal high stress levels than controls, with a significant correlation between respiratory parameters and all PSI-SF scores. Moreover, mothers of affected children showed significantly differences in emotion-oriented and avoidance-oriented coping tasks. The present study suggested the importance of evaluation for caregivers of children affected by OSAS

U-PHOS Project: Development of a Large Diameter Pulsating Heat Pipe Experiment on board REXUS 22

U-PHOS Project aims to analyse and characterise the behaviour of a large diameter Pulsating Heat Pipe (PHP) on board REXUS 22 sounding rocket. A PHP is a passive thermal control device consisting of a serpentine capillary tube, evacuated, partially filled with a working fluid and finally sealed. In this configuration, the liquid and vapour phases are randomly distributed in the form of liquid slugs and vapour plugs. The heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. On ground conditions, a small diameter is required in order to obtain a confined slug flow regime. In milli-gravity conditions, buoyancy forces become less intense and the PHP diameter may be increased still maintaining the slug/plug flow configuration typical of the PHP operation. Consequently, the PHP heat power capability may be increased too. U-PHOS aims at proving that a Large Diameter PHP effectively works in milli-g conditions by characterizing its thermal response during a sounding rocket flight. The actual PHP tube is made of aluminum (3 mm inner diameter, filled with FC-72), heated at the evaporator by a compact electrical resistance, cooled at the condenser by a Phase Change Material (PCM) embedded in a metallic foam. The tube wall temperatures are recorded by means of Fibre Bragg Grating (FBG) sensors; the local fluid pressure is acquired by means of a pressure transducer. The present work intends to report the actual status of the project, focusing in particular on the experiment improvements with respect to the previous campaign