Monitoring the strength gain of structural adhesives using the electromechanical impedance technique: An experimental investigation

Structural adhesives are employed to externally bond fibre-reinforced polymer (FRP) composites onto concrete structures for repair and strengthening purposes. The strength development of the bond layer is important to ensure the overall performance of the FRP-strengthened system. The non-destructive piezoelectric-based monitoring technique, namely the electromechanical impedance (EMI) technique, is introduced to monitor the strength gain of structural adhesives. In this study, the curing process of the commercially available structural adhesive, Sikadur 330, was monitored using the EMI technique. Throughout the experimental study, the 7-day strength gain of the adhesive was observed from the movement of acquired frequency peaks. The frequency peaks moved noticeably to the right for the first 24 hours. After that, the rate of movement decreased significantly. An empirical equation is established to correlate the tensile strength of the adhesive to the acquired resonance frequency for different curing durations. The current study shows the capability of the EMI technique to monitor the strength gain of structural adhesives, particularly at an early age of curing

Monitoring the curing process of structural adhesives using the electromechanical impedance technique: A numerical investigation

Structural adhesives act as a bonding agent to externally bond fibre-reinforced polymer (FRP) composites onto existing structures for strengthening purposes. The performance of FRP-strengthened systems are therefore affected by the strength and stiffness of the structural adhesive layer. The lead zirconate titanate (PZT)-based electromechanical impedance (EMI) technique was employed in this study to monitor the stiffness development process of structural adhesives. A finite element model was developed to investigate the interaction between the PZT patches and the structural adhesive throughout the curing process. The dynamic elastic modulus of the structural adhesives can be predicted from the simulated EMI signatures. The EMI signatures were compared with experimental results for verification purposes. An empirical equation was established to predict the elastic modulus of structural adhesives from the resonance frequency. The current study can be extended by developing a model that predicts the tensile strength of structural adhesives at different curing durations

Use of virtual reality technique for the training of motor control in the elderly: Some theoretical considerations

Virtual augmented exercise, an emerging technology that can help to promote physical activity and combine the strengths of indoor and outdoor exercise, has recently been proposed as having the potential to increase exercise behavior in older adults. By creating a strong presence in a virtual, interactive environment, distraction can be taken to greater levels while maintaining the benefits of indoor exercises which may result in a shift from negative to positive thoughts about exercise. Recent findings on young participants show that virtual reality training enhances mood, thus, increasing enjoyment and energy. For older adults virtual, interactive environments can influence postural control and fall events by stimulating the sensory cues that are responsible in maintaining balance and orientation. However, the potential of virtual reality training has yet to be explored for older adults. This manuscript describes the potential of dance pad training protocols in the elderly and reports on the theoretical rationale of combining physical game-like exercises with sensory and cognitive challenges in a virtual environmen

The Role of Extracellular Vesicles in the Progression of ALS and Their Potential as Biomarkers and Therapeutic Agents with Which to Combat the Disease

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that impairs motor neuron function, leading to severe muscular atrophy. The non-cell autonomous and heterogeneous nature of the disease has so far hindered attempts to define ALS etiology, leaving the disease incurable and without effective treatments. Recent studies have focused on the pathologic role of intercellular communication between nerve cells to further our understanding of ALS pathophysiology. In this chapter, we summarize recent works investigating the role of extracellular vesicles (EVs) as a means of cellular crosstalk for ALS disease propagation, diagnosis, and treatment. There is growing evidence that EVs secreted by the majority of mammalian cells serve as effective biomolecule carriers to modulate recipient cell behavior. This underscores the need to understand the EV-mediated interplay that occurs within irreversibly degenerating nervous tissue in ALS patients. Additionally, we highlight current gaps in EV-ALS research, especially in terms of the pathologic role and responsibilities of specific EV cargos in diseased cells, specificity issues associated with the use of EVs in ALS diagnosis, and the efficacy of EV-mediated treatments for the restoration of diseased neuromuscular tissue. Finally, we provide suggestions for future EV-ALS research to better understand, diagnose, and cure this inveterate disease

Protein-mediated dethreading of a biotin-functionalised pseudorotaxane

In this article, we describe the synthesis of new biotin-functionalised naphthalene derivatives 3 and 4 and their complexation behaviour with avidin and neutravidin using a range of analytical techniques. We have shown using 2-(4prime or minute-hydroxyazobenzene)benzoic acid displacement and ITC experiments{,} that compounds 3 and 4 have the propensity to form reasonably high-affinity bioconjugates with avidin and neutravidin. We have also demonstrated using 1H NMR{,} UV-vis and fluorescence spectroscopy that the naphthalene moiety of 3 and 4 facilitates the formation of pseudorotaxane-like structures with 1 in water. We have then investigated the ability of avidin and neutravidin to modulate the complexation between 1 and 3 or 4. UV-vis and fluorescence spectroscopy has shown that in both cases the addition of the protein disrupts complexation between the naphthalene moieties of 3 and 4 with 1

Two classes of ideals determined by integer-valued polynomials

If D is a domain with quotient field K, let Int(D) = {f(X) ∈ K[X] | f(d) ∈ D for every d ∈ D} be the ring of integer-valued polynomials over D. It is well known that the binomial polynomials GX n H = X(X−1)...(X−n+1) n! form a basis of Int(ZZ) as a free ZZ-module and that for every prime integer p, the Fermat polynomials fp(X) = 1 p (Xp − X) are in Int(ZZ). If the domain D contains ZZ, for each nonnegative integer n, set C(n) = {α ∈ K | α GX n H ∈ Int(D)}, and for every prime integer p, set E(p) = {α ∈ K | α · fp(X) ∈ Int(D)} . Each C(n) and E(p) is an ideal of D which we explicitly determine when D is a Dedekind domain

The Norwich Patellar Instability Score:validity, internal consistency and responsiveness for people conservatively-managed following first-time patellar dislocation

Background: This paper assessed the validity, internal consistency, responsiveness and floor-ceiling effects of the Norwich Patellar Instability (NPI) Score for a cohort of conservatively managed people following first-time patellar dislocation (FTPD).  Methods: Fifty patients were recruited, providing 130 completed datasets over 12 months. The NPI Score, Lysholm Knee Score, Tegner Level of Activity Score and isometric knee extension strength were assessed at baseline, six weeks, six and 12 months post-injury.  Results: There was high convergent validity with a statistically significant correlation between the NPI Score and the Lysholm Knee Score (p < 0.001), Tegner Level of Activity Score (p < 0.001) and isometric knee extension strength (p < 0.002). Principal component analysis revealed that the NPI Score demonstrated good concurrent validity with four components account for 70.4% of the variability. Whilst the NPI Score demonstrated a flooring-effect for 13 of the 19 items, no ceiling effect was reported. There was high internal consistency with a Cronbach Alpha value of 0.93 (95% CI: 0.91 to 0.93). The NPI Score was responsive to change over the 12 months period with an effect size of 1.04 from baseline to 12 months post-injury.  Conclusions: The NPI Score is a valid tool to assess patellar instability symptoms in people conservatively managed following FTPD.  Level of evidence: Level I

A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel

Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al ‘ring’ defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed-charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well-predicted by the empirical potentials both for point defects and small defect clusters

Video-assisted thoracoscopic lobectomy: which patients require postoperative physiotherapy?

Objectives: Following major thoracic surgery physiotherapy is recommended to improve reduced lung volume, aid secretion clearance, and improve mobility, however, in many centres physiotherapy provision is variable following minimally invasive video-assisted thoracoscopic surgery (VATS). The objective of this study was to observe frequency of problems potentially amenable to physiotherapy following VATS lobectomy, and to identify associated baseline factors of patients in whom physiotherapy may be beneficial. Methods: A prospective observational study was performed including all consecutive cancer patients undergoing VATS lobectomy in a regional centre over 4 years (2012–2016). Standard postoperative care included early mobilisation by nursing staff from postoperative day one (POD1). Physiotherapy assessment of all patients on POD1 determined presence of issues potentially amenable to physiotherapy intervention, and treatment was commenced. Outcome measures included postoperative pulmonary complication (PPC) development, hospital and high dependency unit (HDU) length of stay (LOS). Results: Of 285 patients, 209 (73%) received physiotherapy to assist/improve reduced mobility, of these 23 (8%) also received sputum clearance therapies and 65 (23%) specific therapy for lung volume loss. The remaining 76 (27%) patients had significantly lower hospital/HDU LOS (P &lt; 0.001) reflecting uncomplicated recovery. Chronic obstructive pulmonary disease (COPD), body mass index (BMI), preoperative mobility and age were independently associated with issues potentially amenable to physiotherapy (P = 0.013). Conclusion: Following VATS lobectomy a large proportion of patients demonstrated issues potentially amenable to physiotherapy. The authors recommend that patients receive routine physiotherapy assessment following this type of surgery to ensure that all issues are identified early. Screening of COPD, BMI, preoperative mobility and age will allow early identification of patients who may benefit most from postoperative physiotherapy and preoperative optimisation, however, these factors cannot predict the need for physiotherapy