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To investigate the effect of the stability of oxygen vacancies on the low-temperature degradation (LTD) resistance of two kinds of commercial zirconia-based materials (3Y-TZP ceramics and Ce-TZP/Al 2 O 3 composites) via the dielectric probing methods. The commercial 3Y-TZP ceramics and Ce-TZP/Al 2 O 3 composites were prepared via conventional solid-state methods. Density, phase content, microstructure, strain, and biaxial flexural strength (BFS) of two materials were investigated using Archimedes method, XRD, SEM, strain-electric field (S-E) loops and ball-on-ring methods, respectively. The concentration of oxygen vacancies before and after LTD of two materials were evaluated using dielectric probing and XPS methods. The XRD analysis revealed that compared to the 3Y-TZP ceramics, the Ce-TZP/Al 2 O 3 composites showed better LTD resistance, without clear LTD. The greater LTD resistance for Ce-TZP/Al 2 O 3 composites was associated with their stability of oxygen vacancies, by higher activation energy based on the dielectric measurements and XPS results. For the 3Y-TZP ceramics that underwent the tetragonal to the monoclinic phase transition during the LTD treatment, the concentration of their oxygen vacancies decreased after LTD. In addition, the Ce-TZP/Al 2 O 3 composites exhibited higher flexural strength and potential fracture toughness based on the BFS testing and strain vs electric field measurement results, indicating a great potential for use in fixed restorative dental applications. This work suggested the stability of oxygen vacancies played a key role in the resistance to LTD. Optimizing the stability of the oxygen vacancies is key to the development of more reliable zirconia- based dental biomaterials with greater resistance to LTD. • LTD observed in the 3Y-TZP ceramics, accompanied with their decrease concentration of oxygen vacancies. • The stability of oxygen vacancies in the Ce-TZP/Al 2 O 3 composites played an important role in their resistance to LTD. • Dielectric probing was proved to be a useful method to investigate the LTD of zirconia bio-ceramics. [ABSTRACT FROM AUTHOR]

Abstract Advanced composite materials have been investigated for repair of fatigue-damaged metal structures, but one of the challenges is the repair often covers-up underlying damage, preventing visual inspection. A novel approach where a carbon nanotube-based sensing layer integrated in a steel/composite adhesive bond has been investigated as an approach for repair while adding capability to detect the adhesive bond integrity and monitor propagation of cracks in the underlying substrate. The sensing layer, composed of a random mat of aramid fibers coated with carbon nanotubes, offers tremendous application flexibility for integration of sensing capabilities in structures. Experiments examining fatigue crack propagation in structural steel with a composite repair and integrated bondline sensing increased the fatigue life by 380% to over 500%, depending on configuration. The sensing layer was able to monitor deformation and crack propagation in real-time and shows potential for use in periodic inspection-based monitoring of cracks using electrical property changes. [ABSTRACT FROM AUTHOR]

Laboratory experiments demonstrate that a novel carbon nanotube (CNT)-based sensing layer embedded in the bondline of an adhesively bonded structural joint can detect and monitor deformation and damage progression of the adhesive layer. In this study, experimental and numerical investigations were performed to identify any effect of an embedded CNT-based sensing layer on the bond strength of that joint. To evaluate the mechanical behavior of such a bondline configuration, two sets of single-lap specimens, with and without sensing layer, were prepared and tested to determine the bond strengths of the respective types. Two-dimensional digital image correlation (2D DIC) was utilized to estimate the load-displacement response of the test specimens. Three-dimensional cohesive surface finite element models of the test specimens, with and without the sensing layer, were created and validated using the experimental measurements. It is shown that the embedded CNT-based sensing layer does not influence the bond strength of the single-lap joint. [ABSTRACT FROM AUTHOR]

Background The population flow dynamics of Hajj increases the probability of pneumococcal acquisition and amplification among Hajis. This multi-site longitudinal molecular surveillance study was designed to assess the impact and potential variations of pneumococcal carriage in a single cohort of pre and post-Hajj pilgrims from India. Method A total of 3228 pre and post-Hajj, nasopharyngeal and oropharyngeal swabs were collected from 807 pilgrims with an interval of 40 ± 5 days. The carriage was detected by culture and qmPCR. Quellung test, mPCR-FAF, PCRseqTyping, and MLST was used for typing. Antibiogram was performed by MIC method. Results An increased incidence of pneumococcal carriage was detected in post Hajj cohort by qmPCR (19% vs 21.8%) (p-value = 0.0487) and culture (6.5% vs 8.2%) (p-value = 0.0645). Fragment analysis could identify multiple serotype carriage in 76 pilgrims. Increase in drug resistance was also observed in post-hajj cohort for Tetracycline (29% vs 51%), Erythromycin (26% vs 46%) and Levofloxacin (6% vs 17%). Multidrug resistant strains in post Hajj group was 32% compared to 11% in pre Hajj group (p-value = 0.0002). Conclusion Our results confirm high acquisition rate of multidrug-resistant S. pneumoniae in Hajj pilgrims and highlight its potential spread to home countries upon their return. Surveillance studies are needed to evaluate modifiable factors associated with carriage. [ABSTRACT FROM AUTHOR]

A single phase four-layer Aurivillius structured ferroelectric ceramic, (Ca 0.2 Sr 0.2 Ba 0.2 Pb 0.2 Nd 0.1 Na 0.1)Bi 4 Ti 4 O 15 (6ABTO) was obtained using a high entropy design concept. The material, which has orthorhombic symmetry in space group A 2 1 am at room temperature, has Ca2+, Sr2+, Ba2+, Pb2+, Nd3+ and Na+ distributed not only on the A sites of the perovskite layer but also in the bismuthate layer. 6ABTO shows complex ferroelectric behavior, with a Curie point of 557 °C. Four current peaks are observed in the current - electric field curve. These peaks are attributed to a combination of a field induced phase transition and domain wall switching, which is the first reported occurrence of such current - electric field behavior for an Aurivillius structured ferroelectric material. Despite the level of disorder between the A site cations in the perovskite layer and the Bi positions in the bismuthate layer, 6ABTO does not show the relaxor ferroelectric behavior, that is commonly observed in cases of such disorder. This suggests that relaxor behavior in ferroelectrics, may be more associated with the thermal stability of dipoles, rather than the presence of polar nano-regions formed as a result of chemical disorder. The nature of the high entropy effect in 6ABTO is discussed through comparison of results from isostructural compositions containing 5, 4 and 3 of the component cations [Display omitted] [ABSTRACT FROM AUTHOR]

• Higher concentrations of elements in non-famous Basmati rice growing regions. • Higher δ13C values of Basmati rice growing regions compared to other regions. • PLS-DA was found to be effective in grouping rice samples from different regions. High-priced Basmati rice is vulnerable to deliberate mislabeling to increase profits. This type of fraud may lower consumers' confidence as inferior products can affect brand reputation. To address this problem, there is a need to devise a method that can efficiently distinguish Basmati rice grown in regions that are famous versus the regions that are not suitable for their production. Therefore, in this investigation, thirty-six samples of Basmati rice were collected from two zones of Punjab province (one known for Basmati rice) of Pakistan which is the major producer of Basmati rice. The elemental composition of rice samples was assessed using inductively coupled plasma-optical emission spectrometry and an organic elemental analyzer, whereas data on δ13C was acquired using isotopic ratio-mass spectrometry. Regional clustering of samples based on their respective cultivation zones was observed using multivariate data analysis techniques. Partial least squares-discriminant analysis was found to be effective in grouping rice samples from the different locations and identifying unknown samples belonging to these two regions. Further recommendations are presented to develop a better model for tracing the origin of unidentified rice samples. [ABSTRACT FROM AUTHOR]