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New procedure for the examination of the degradation of volatile organonitrogen compounds during the treatment of industrial effluents
No full textWe present a new procedure for the determination of 32 volatile organonitrogen compounds in samples of industrial effluents with a complex matrix. The procedure, based on dispersive liquid-liquid microextraction followed by gas chromatography with nitrogen-phosphorus and mass spectrometric detection, was optimized and validated. Optimization of the extraction included the type of extraction and disperser solvent, disperser solvent volume, pH, salting out effect, extraction and centrifugation time. The procedure based on nitrogen-phosphorus detection was found to be superior, having lower limits of detection (0.0067-2.29 μg/mL) and quantitation as well as a wider linear range. The developed procedure was applied to the determination of content of volatile organonitrogen compounds in samples of raw effluents from the production of bitumens in which 13 compounds were identified at concentrations ranging from 0.15 to 10.86 μg/mL and in samples of effluents treated by various chemical methods. This article is protected by copyright. All rights reserved
Comparison of Lithium-Ion Anode Materials Using an Experimentally Verified Physics-Based Electrochemical Model
Get PDFResearchers are in search of parameters inside Li-ion batteries that can be utilized to control their external behavior. Physics-based electrochemical model could bridge the gap between Li+ transportation and distribution inside battery and battery performance outside. In this paper, two commercially available Li-ion anode materials: graphite and Lithium titanate (Li4Ti5O12 or LTO) were selected and a physics-based electrochemical model was developed based on half-cell assembly and testing. It is found that LTO has a smaller diffusion coefficient (Ds) than graphite, which causes a larger overpotential, leading to a smaller capacity utilization and, correspondingly, a shorter duration of constant current charge or discharge. However, in large current applications, LTO performs better than graphite because its effective particle radius decreases with increasing current, leading to enhanced diffusion. In addition, LTO has a higher activation overpotential in its side reactions; its degradation rate is expected to be much smaller than graphite, indicating a longer life span
Introduction
No full textShock & Vibration, Aircraft/Aerospace and Energy Harvesting, Volume 9: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the ninth volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Shock & Vibration, Aircraft/Aerospace and Energy Harvesting including papers on: • Shock & Vibration Testing • Aircraft/Aerospace Applications • Optical Techniques: Digital Image Correlation • Vibration Suppression & Control • Damage Detection • Energy Harvestin
Optimizing Hybrid Plate Fixation with a Locked, Oblique End Screw in Osteoporotic Fractures
Get PDFBackground The end screw in a fracture plate creates the greatest resistance to bending. For osteoporotic fractures treated with plates, there is some question as to the optimal screw insertion technique for the screw farthest from the fracture. A locked, oblique end screw was previously shown to increase resistance to periprosthetic fracture. It is unknown, however, how this end screw configuration would resist pullout when subjected to bending. Methods Narrow, low contact 3.5 mm locking compression plates with 6 and 12 holes were anchored to simulated bone material with material properties representing osteoporotic bone. Four configurations were evaluated for the end screw: perpendicular and angulated 30 degrees away from the fracture for both non-locked and locked screws (n=6 per group). The constructs were subjected to 3 point bending until the peak load and finally total construct failure was achieved. Results Peak force, stiffness, energy to peak load, and the failure mode of each construct were determined. All four 12-hole construct groups failed by gross plastic bending deformation of the plate at the fulcrum past a previously established clinically relevant limit for failure (15°). All 12-hole plate constructs failed at statistically higher loads and energy than any of the 6-hole plate constructs, with the exception of the 6-hole locked, oblique construct. Conclusion The locked, oblique end screw provides equivalent pull out strength for 3.5 mm low contact plates regardless of plate length. Combined with its resistance to periprosthetic fracture, this end screw configuration appears to be the best option for the construct integrity of hybrid plating for osteoporotic fractures. Clinical Relevance Osteoporotic fractures are challenging to treat. The current study and the existing literature show that resistance to both bending loads and refracture at the end of a plate are minimized with a locked screw angled away from the fracture
A Sliding Hip Screw Augmented with 2 Screws is Biomechanically Similar to an Inverted Triad of Cannulated Screws in Repair of a Pauwels Type-III Fracture
No full textObjective Pauwels III femoral neck fractures are highly unstable. These fractures are commonly treated with three cannulated screws or sliding hip screw (SHS) implants, however high rates of non-union persist. A hybrid SHS construct has recently been proposed. The objective of the study was to compare this construct to the familiar inverted triad of cannulated screws and to a single SHS. Methods Fourth generation biomechanical femur analogs were used to create a highly repeatable injury model. The hybrid SHS construct contained a SHS with two superior cannulated screws in an inverted triangle configuration. Eight samples for each construct were biomechanically evaluated and the results compared using ANOVA (p \u3c 0.05). Results The cannulated triad and hybrid SHS provided similar stiffness and fracture gap motion. The single SHS exhibited significantly lower stiffness and larger fracture plane diastasis than either the inverted triangle of cannulated screws or hybrid SHS (p \u3c 0.05). None of the constructs exhibited catastrophic failure during cyclic loading nor under loading up to 2.5 times body weight. Conclusions The single SHS provided the least stable fracture fixation, while the inverted triad and hybrid SHS constructs were mechanically similar. The fracture repair simulated here illustrates how these repairs have the potential to return near pre-fracture strength in ideal conditions with young, healthy bone. However; in clinical situations where comminution impairs load transfer through the cortices the hybrid SHS may be the most favorable option
The New Surgical Technique for Improving Total Knee and Hip Arthroplasty Outcomes: Patient Selection
No full textBackground: Inclusion of patient satisfaction scores in setting reimbursements has been suggested by health care policy makers to contain cost and improve outcomes. The Short Form 36 Health Survey (SF-36) score provides a health-related quality of life (HRQoL) measure of arthroplasty outcome. Although previous work identified factors that influence this score for hip and knee arthroplasty patients, they did not focus on how a surgeon might use this information in a clinical setting. The present study examined whether relatively simple criteria might identify patients more likely to experience minimal HRQoL improvement. Methods: Improvements in SF-36 composite physical scores and subscales were calculated from the difference between initial (preoperative) and SF-36 scores at 1 year. The rates of achieving a clinically significant improvement were compared between patient groups. Results: After knee arthroplasty, women and younger patients achieved a clinically significant improvement in physical function more frequently than men and older patients (P?= .04 and .02, respectively). The largest differences in improvement occurred between the diabetic and nondiabetic groups (P?= .001), where the diabetic patients with ?2 additional comorbidities demonstrated the lowest rate of achieving a clinically significant improvement in physical function and bodily pain. In comparison, in hip patients only age had significant influence on gains in physical function, but this did not alter the rate at which patients achieved a clinically significant improvement. Conclusion: These data indicate simple screening criteria can identify patients where arthroplasty might provide marginal HRQoL improvement. They suggest HRQoL-based reimbursement incentives will favor practices with younger, healthier patient populations
