Engineering of component surfaces using Laser Shock Peening (LSP) requires optimisation of key process parameters to enhance performance through the generation of beneficial compressive residual ...stresses. Quantification of residual stress fields typically requires considerable experimental resources involving multiple complementary techniques to obtain reliable measurements through the depth of the target material. LSP induced plastic strains lead to the formation of residual stresses and cause deformation of thin components. This effect is routinely used in the assessment of mechanical Shot Peening (SP) where distortion coupons, called Almen strips, correlate the peening intensity to process parameters. This study explores the extension of this Almen strip concept to facilitate the quick assessment of LSP parameters for aluminium alloy 6056-T4 aeronautical structural applications. Direct measurements of the resulting LSP residual stresses have been performed using Synchrotron X-Ray Diffraction, Neutron Diffraction, and Incremental Hole Drilling, complemented by analyses of surface integrity and sub-surface modifications. It has been found that the attained near-surface compressive residual stress values and depths are strongly dependent on laser power intensity and spot coverage, whilst surface roughness and microhardness are mostly independent of the LSP parameters. Optimal parameter selection should therefore be primarily focused on the required residual stress field. A direct correlation has been observed between the magnitudes of LSP Almen distortions and the residual stresses. This qualifies extending the deflection based approach to be used as a quick, simple and effective qualitative screening technique of LSP process parameters, such as the laser power intensity saturation.
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•Laser Shock Peening parameter sets were identified for Aluminium Alloy 6056-T4•LSP residual stress profiles were characterised using complementary techniques•A strain energy and energy conversion efficiency methodology was developed•Distortions of LSP Almen coupons correlated well to measured residual stresses•A distortion approach was validated for initial LSP process parameters screening
Imidacloprid is a systemic neonicotinoid insecticide widely used to combat agricultural pests and flea infestations in dogs and cats. Despite its low toxicity to mammals, imidacloprid is reported to ...cause male reproductive toxicity. This study evaluated the cytotoxic effects of 75-800 μM imidacloprid on a rat Leydig cell line (LC-540). The effect of exposure to 300, 400, and 500 µM imidacloprid on selected cytoskeletal proteins, mitochondrial morphology, lysosomal acidity, and ultrastructure were investigated. Cell viability was markedly reduced after 48 and 72 h of exposure to higher imidacloprid concentrations. The immunocytochemical analysis revealed that the cytoskeletal filaments exhibited disorganization, disruption, and perinuclear aggregation in treated LC-540 cells. Ultrastructurally, cytoplasmic vacuoles, autophagic vacuoles, lysosomes, and mitochondrial damage were detected. Changes in the mitochondrial morphology and lysosomes induced by imidacloprid were confirmed. The cytotoxicity of imidacloprid observed in LC-540 cells might be due to its mitochondrial damage and cytoskeletal protein disruption.
To report the effectiveness, patient satisfaction, and complication rate with a zonal refractive intraocular lens (IOL) in a high volume of patients.
Private clinic, London, United Kingdom.
Case ...series.
Retrospective data of patients with binocular Lentis Mplus IOLs were analyzed. The main outcome measures were uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity, manifest refraction, patient satisfaction, and complications. One-month, 3-month, and 6-month data were analyzed.
The study comprised 9366 eyes of 4683 patients. The mean spherical equivalent changed from +1.73 diopters (D) ± 3.37 (SD) preoperatively to -0.02 ± 0.60 D at 3 months and +0.03 ± 0.60 D at 6 months. Ninety-five percent of patients achieved a binocular UDVA of 6/7.5 (0.1 logMAR) or better 3 months postoperatively. The mean binocular UNVA was 0.155 ± 0.144 logMAR and 0.159 ± 0.143 logMAR at 3 months and 6 months, respectively. Severe dysphotopsia requiring an IOL exchange occurred in 55 eyes. Patient satisfaction was high, with 97.5% of patients willing to recommend the procedure.
The zonal refractive IOL provided excellent distance and near visual acuity. The postoperative complication rate was clinically acceptable, and patient satisfaction high.
Dr. Schallhorn is a consultant to Abbott Medical Optics, Inc. No author has a financial or proprietary interest in any material or method mentioned.
The structural properties and electrical conductivities of nine CaO−MgO−Al2O3−SiO2 slags with compositions in the peralkaline region have been calculated using molecular dynamics simulations. The ...proportion of nonbridging oxygen (NBO) and bridging oxygen (BO) atoms were determined from simulation and shown to be in reasonable agreement with theoretical prediction. Bridging oxygen atoms were classified into Si−O−Si, Si−O−Al or Al−O−Al linkages and the results used to establish whether the Al avoidance principle is applicable. The number of bridging oxygens coordinated to tetrahedral SiO44− and AlO45− units, namely the Qn distribution, was determined. Although a good comparison to the theoretical average Q was found at low basicity, at higher basicity greater deviation was seen. Electrical conductivities, taking cross-correlations into account, were in excellent agreement with experimentally measured values, although Nernst–Einstein conductivities, estimated from self-diffusion coefficients alone, showed large deviations. Molecular dynamics simulations are therefore able to reliably predict conductivity, but values calculated indirectly, i.e. using the Nernst–Einstein relationship, should be used with care. At low basicity theoretical predictions of structural disorder, based on Zachariasen's Random Network Model, are in reasonable agreement with simulation, but this agreement worsens as the proportion of network modifying cations increases.
•Simulated structural properties compare well with estimates from composition alone.•Deviations from theoretical relationships become larger at higher basicity.•Ionic motion is distinctive for structure breaking and structure forming ions.•Electrical conductivity can be calculated accurately using correlated ionic motion.•Conductivity predictions using the Nernst–Einstein expression require care.
Background. COVID-19 was recognised as a global pandemic on 11 March 2020. In South Africa (SA), a nationwide lockdown was implemented at midnight on 26 March to prepare for the predicted surge and ...slow the spread of the virus. Objectives. To compare the volume and type of presentations of trauma secondary to interpersonal violence and road traffic collisions (RTCs) during two 5-month periods, from February to June 2019 and 2020, in the emergency department (ED) of an academic tertiary hospital in Gauteng Province, SA. In 2020, February - June included the lockdown period. Methods. An observational retrospective audit of the patient register at the Helen Joseph Hospital ED was conducted, comparing the number of trauma presentations secondary to interpersonal violence (assaults with gunshot wounds, general assaults including mob assaults, assaults with stab wounds) and RTC presentations between February and June 2019 and 2020. Results. A total of 4 300 trauma presentations secondary to interpersonal violence and RTCs were noted in the 5-month period February June 2019, as opposed to 3 239 presentations in February - June 2020 (25% decline). A 40% decline in the number of RTCs, from 1 704 in February - June 2019 to 1 026 in the corresponding period for 2020, was noted and found to be statistically significant (p=0.03). Declines in the volume of trauma cases secondary to interpersonal violence and of overall trauma cases were only directional in favour of 2020, but not statistically significant. Conclusions. The volume of trauma presentations secondary to interpersonal violence and RTCs in the Helen Joseph Hospital ED decreased during the lockdown period. The decline in the volume of RTCs was statistically significant, but declines in the volume of trauma presentations secondary to interpersonal violence and in the volume of overall trauma presentations were not.
Delamanid (OPC-67683) is a novel mycolic acid biosynthesis inhibitor active against Mycobacterium tuberculosis at a low minimum inhibitory concentration.
Forty-eight patients with smear-positive ...tuberculosis (63% male; 54.7 ± 9.9 kg; 30.7 ± 10.8 years) were randomly assigned to receive delamanid 100, 200, 300 or 400 mg daily for 14 days. Colony forming units (cfu) of M. tuberculosis were counted on agar plates from overnight sputum collections to calculate early bactericidal activity (EBA), defined as fall in log(10) cfu/ml sputum/day.
The EBA of delamanid was monophasic and not significantly different between dosages; however, more patients receiving 200 mg (70%) and 300 mg (80%) experienced a response of ≥0.9 log(10) cfu/ml sputum decline over 14 days than those receiving 100 mg (45%) and 400 mg (27%). The average EBA of all dosages combined (0.040 ± 0.056 log(10) cfu/ml sputum/day) was significant from day 2 onward. Delamanid exposure was less than dosage-proportional, reaching a plateau at 300 mg, likely due to dose-limited absorption. Moderate but significant correlation was found between C(max) and EBA, indicating exposure dependence. Delamanid was well tolerated without significant toxicity.
Delamanid at all dosages was safe, well tolerated and demonstrated significant exposure-dependent EBA over 14 days, supporting further investigation of its pharmacokinetics and anti-tuberculosis activity.
Gold nanoparticles (AuNPs) have enormous potential for application in imaging, diagnosis, and therapies in the medical field. AuNPs are renowned for their localized surface plasmon resonance (LSPR) ...properties, large surface area, and biocompatibility with body fluids. Further, AuNPs have featured prominently in new methodologies for cancer treatments, like photothermal and imaging therapies. Although AuNPs present enormous potential for application in the medical field, their instability under physiological conditions prevents further uses. However, this limitation may be overcome by associating AuNPs with biopolymers. To the best of our knowledge, a revision paper rationalizing the structure/property relationship and applications of AuNPspolysaccharide composites in the medical field has not been published yet.
This manuscript discusses the most relevant aspects and state-of-art concepts surrounding the synthesis of AuNPs based on green chemistry and their association with polysaccharides that can efficiently function both as stabilizing and reducing agents of Au nanoparticles. Even more, polysaccharide devices may inhibit non-specific interactions between AuNPs and biological macromolecules, suppressing unsuitable "protein corona" formations on AuNP surfaces, thereby increasing the potential of AuNP composites of being employing as drug delivery matrices and wound-healing devices as well as in photothermal/ imaging purposes for cancer treatments and biosensors.
Participatory modelling (PM) is focused on actively involving enterprise stakeholders and modelling experts in the modelling process. Typically, participants are co-located and encouraged to ...collaborate to avoid conceptual misalignment. During Covid-19, however, people were forced to reduce significantly their physical interactions, which led to the embracing of virtual tools. However, limited research has been done to evaluate virtual tools for the purpose of PM or participatory enterprise modelling (PEM), and specifically for the ease-of-use or usability of these tools. Many standardised usability questionnaires are available to evaluate the usability of user interfaces or systems. We provide key criteria for selecting an appropriate standardised questionnaire to measure PM tool usability and, as the main contribution, examine in a controlled experiment the usability of an online tool, MURAL, when participants use PEM. We report on the tool’s usability, using the selected standardised usability questionnaire, and present insights obtained through interviews and observations.
Investigation of the residual stresses and microstructural properties associated with HVOF thermal spray coating of WC-17wt% Co of same thickness on three substrates with coefficients of thermal ...expansion different to that of WC. The residual stresses were measured by X-ray diffraction sin2ψ techniques using CoKα radiation. The results indicated residual stresses that have different natures for the as-sprayed coatings despite using the same powder as feedstock. The magnitudes of the stresses in the as-sprayed condition are low.
► Stress analysis of the coating was measured via X-ray diffraction by using Co-Kα radiation source. ► The as-sprayed coatings render the values that are both tensile and compressive on the substrate despite same powder as feedstock. ► A strong correlation exist between residual stress results and SEM micrographs.
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