Efficacy of different solvents in removing gutta‐percha from curved root canals: A micro‐computed tomography study

The aim of this study was to compare the root filling material that remained after retreatment of curved root canals with chloroform and Endosolv R as solvents. The evaluation employed micro‐computed tomography (CT) imaging. Thirty‐six extracted molar teeth with curved roots were selected. After preparation with ProTaper rotary instruments, the canals were filled with gutta‐percha and AH26 sealer. The teeth were randomly divided into three groups according to solvent used (n = 12) as follows: group 1: chloroform; group 2: Endosolv R; group 3: no solvent (negative control). ProTaper Universal Retreatment files were used to remove each root canal filling and then the self‐adjusting file was applied for two minutes. Preoperative and postoperative micro‐CT images were used to assess the percentage of residual filling material. The mean percentage of residual filling material was quantified. There were no statistically significant differences between the groups in terms of percentage volume of residual root canal filling.     

Rat intercostal nerves as experimental nerve grafts

In this study, we dissected and measured both sets of intercostal nerves including lengths, diameters, and axon counts in 12 adult rats to provide data applicable to experimental nerve graft research. Dissections showed that total lengths of intercostal nerves from the spinal bifurcation to their last arborizations near the midline ranged from 10 to 89 mm, and diameters ranged from less than 0.1 to 0.5 mm from the thinnest to the thickest part. The segment of easiest dissection was the part between the spinal bifurcation and the lateral cutaneous branch. This part was 4–27 mm (mean, 13.3 mm) long and had an almost constant diameter of 0.18–0.5 mm (mean, 0.32 mm). Counts ranged from 201 to 566 axons/nerve. The segment proximal to the lateral cutaneous branch was the most convenient part to be harvested as a nerve graft, especially in the 8th to 12th intercostal nerves. These nerves could serve as sources for experimental grafts. © 1996 Wiley-Liss, Inc.     

Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl2O4

The drawback of the hydrothermal technique is driven by the fact that it is a time-consuming operation, which greatly impedes its commercial application. To overcome this issue, conventional hydrothermal synthesis can be improved by the implementation of microwaves, which should result in enhanced process kinetics and, at the same time, pure-phase and homogeneous products. In this study, nanometric zinc aluminate (ZnAl₂O₄) with a spinel structure was obtained by a hydrothermal method using microwave reactor. The average ZnAl₂O₄ crystallite grain size was calculated from the broadening of XRD lines. In addition, BET analysis was performed to further characterize the as-synthesized particles. The synthesized materials were also subjected to microscopic SEM and TEM observations. Based on the obtained results, we concluded that the grain sizes were in the range of 6–8 nm. The surface areas measured for the samples from the microwave reactor were 215 and 278 m² g⁻¹.     

Investigation of Dynamic Thiol/Disulfide Homeostasis and Nitrosative Stress in Patients with Wilson Disease

Background: Wilson disease (WD) is an autosomal recessive inherited disorder of copper (Cu²⁺) metabolism, resulting in Cu²⁺ accumulation and liver and central nervous system toxicity. Oxidative stress may have a role in the pathogenesis of Wilson disease, but the roles of thiol/disulfide homeostasis and nitrosative stress have not been examined. The purpose of this study was to evaluate whether there is a modification in thiol/disulfide homeostasis and nitrosative stress in patients with Wilson disease.Methods: A total of 50 patients with Wilson disease (42 under drug treatment and 8 newly diagnosed patients with no drug treatment) and 50 healthy gender- and age-matched controls were enrolled for this study. Serum native thiol and total thiol levels were measured with a spectrophotometric method. The number of disulfide bonds and the related ratios were determined from these measurements. Serum nitric oxide (NO) and 3-nitrotyrosine (3-NT) levels were analyzed using chemiluminescence and ELISA assays, respectively.Results: The average native thiol levels of the patient group under drug treatment were found to be markedly higher than the levels of controls (P < .05). We detected no marked changes in total thiol and disulfide levels, and disulfide/total thiol, disulfide/native thiol, or native thiol/total thiol ratios between groups. We found significant elevations in NO levels in Wilson disease group before drug treatment, and the 3-NT levels in the Wilson disease groups prior to (P < .05) and under drug treatment (P < .01), when compared to controls.Conclusion: Our data are the first to show that nitrosative stress and thiol/disulfide homeostasis can contribute to the pathogenesis of Wilson disease.     

The Springer Model for Lifetime Prediction of Wind Turbine Blade Leading Edge Protection Systems: A Review and Sensitivity Study

The wind energy sector is growing rapidly. Wind turbines are increasing in size, leading to higher tip velocities. The leading edges of the blades interact with rain droplets, causing erosion damage over time. In order to mitigate the erosion, coating materials are required to protect the blades. To predict the fatigue lifetime of coated substrates, the Springer model is often used. The current work summarizes the research performed using this model in the wind energy sector and studies the sensitivity of the model to its input parameters. It is shown that the Springer model highly depends on the Poisson ratio, the strength values of the coating and the empirically fitted a2 constant. The assumptions made in the Springer model are not physically representative, and we reasoned that more modern methods are required to accurately predict coating lifetimes. The proposed framework is split into three parts—(1) a contact pressure model, (2) a coating stress model and (3) a fatigue strength model—which overall is sufficient to capture the underlying physics during rain erosion of wind turbine blades. Possible improvements to each of the individual aspects of the framework are proposed.     

Providing insights into atherosclerosis: A case of multivessel coronary artery disease with an anomalous straightforward vessel spared from atherosclerosis

Atherosclerotic plaques tend to involve arterial localizations in which blood flow is not laminar due to arterial bends and bifurcations. A 49-year-old man was admitted to hospital with breathlessness and was subsequently diagnosed with left ventricular failure. Coronary angiography revealed three-vessel coronary artery disease and an anomalous extra left anterior descending artery taking off from the right sinus of Valsalva and spared from atherosclerosis. The absence of side branches and the relative lack of bends in arterial geometry were considered to be the cause of resistance to atherosclerosis. The present case identifies local flow conditions as an important factor determining the genesis of atherosclerosis in arterial segments.     

Development of Composite,Reinforced, Highly Drug-Loaded Pharmaceutical Printlets Manufactured by Selective Laser Sintering—In Search of Relevant Excipients for Pharmaceutical 3D Printing

3D printing by selective laser sintering (SLS) of high-dose drug delivery systems using pure brittle crystalline active pharmaceutical ingredients (API) is possible but impractical. Currently used pharmaceutical grade excipients, including polymers, are primarily designed for powder compression, ensuring good mechanical properties. Using these excipients for SLS usually leads to poor mechanical properties of printed tablets (printlets). Composite printlets consisting of sintered carbon-stained polyamide (PA12) and metronidazole (Met) were manufactured by SLS to overcome the issue. The printlets were characterized using DSC and IR spectroscopy together with an assessment of mechanical properties. Functional properties of the printlets, i.e., drug release in USP3 and USP4 apparatus together with flotation assessment, were evaluated. The printlets contained 80 to 90% of Met (therapeutic dose ca. 600 mg), had hardness above 40 N (comparable with compressed tablets) and were of good quality with internal porous structure, which assured flotation. The thermal stability of the composite material and the identity of its constituents were confirmed. Elastic PA12 mesh maintained the shape and structure of the printlets during drug dissolution and flotation. Laser speed and the addition of an osmotic agent in low content influenced drug release virtually not changing composition of the printlet; time to release 80% of Met varied from 0.5 to 5 h. Composite printlets consisting of elastic insoluble PA12 mesh filled with high content of crystalline Met were manufactured by 3D SLS printing. Dissolution modification by the addition of an osmotic agent was demonstrated. The study shows the need to define the requirements for excipients dedicated to 3D printing and to search for appropriate materials for this purpose.