scholarly journals Development of a Novel X-ray Compatible 3D-Printed Bone Model to Characterize Different K-Wire Fixation Methods in Support of the Treatment of Pediatric Radius Fractures

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4179
Author(s):  
Anna Gabriella Lamberti ◽  
Zoltan Ujfalusi ◽  
Roland Told ◽  
Dániel Hanna ◽  
Gergő Józsa ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Single Wire ◽  
Bending Tests ◽  
Parallel Wire ◽  
X Ray ◽  
Three Point Bending ◽  
Fixation Methods ◽  
Relative Standard ◽  
Wire Fixation ◽  
3D Printed

Additive manufacturing technologies are essential in biomedical modeling and prototyping. Polymer-based bone models are widely used in simulating surgical interventions and procedures. Distal forearm fractures are the most common pediatric fractures, in which the Kirschner wire fixation is the most widely used operative method. However, there is still lingering controversy throughout the published literature regarding the number of wires and sites of insertion. This study aims to critically compare the biomechanical stability of different K-wire fixation techniques. Different osteosyntheses were reconstructed on 189 novel standardized bone models, which were created using 3D printing and molding techniques, using PLA and polyurethane materials, and it has been characterized in terms of mechanical behavior and structure. X-ray imaging has also been performed. The validation of the model was successful: the relative standard deviations (RSD = 100 × SD × mean−1, where RSD is relative standard deviation, SD is the standard deviation) of the mechanical parameters varied between 1.1% (10° torsion; 6.52 Nm ± 0.07 Nm) and 5.3% (5° torsion; 4.33 Nm ± 0.23 Nm). The simulated fractures were fixed using two K-wires inserted from radial and dorsal directions (crossed wire fixation) or both from the radial direction, in parallel (parallel wire fixation). Single-wire fixations with shifted exit points were also included. Additionally, three-point bending tests with dorsal and radial load and torsion tests were performed. We measured the maximum force required for a 5 mm displacement of the probe under dorsal and radial loads (means for crossed wire fixation: 249.5 N and 355.9 N; parallel wire fixation: 246.4 N and 308.3 N; single wire fixation: 115.9 N and 166.5 N). We also measured the torque required for 5° and 10° torsion (which varied between 0.15 Nm for 5° and 0.36 Nm for 10° torsion). The crossed wire fixation provided the most stability during the three-point bending tests. Against torsion, both the crossed and parallel wire fixation were superior to the single-wire fixations. The 3D printed model is found to be a reliable, cost-effective tool that can be used to characterize the different fixation methods, and it can be used in further pre-clinical investigations.

Automation Of Dihydroxyaluminum Sodium Carbonate Analysis In Antacid Tablets By Energy Dispersive X-Ray Fluorescence

1990 ◽  
Vol 73 (3) ◽  
pp. 385-388
Author(s):  
Constantine A Georgiades
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Sodium Carbonate ◽  
Energy Dispersive ◽  
Computer Data ◽  
X Ray ◽  
Assay Procedure ◽  
Relative Standard ◽  
Computer Data Processing

Abstract A sensitive, specific, automated energy dispersive X-ray fluorescence (EDXRF) method for determination of anhydrous dihydroxyaluminum sodium carbonate in antacid tablets has been developed. The compound was quantltated by Impact grinding, palletizing at 10 tons pressure, and monitoring the aluminum by using a rhodium anode X-ray tube, high resolution thermoelectrlcally cooled SI(LI) detector with sample spinning, and computer data processing. The assay procedure was validated with spiked laboratory-prepared samples at 100 ± 20% levels. The average recovery was 100.6% with a relative standard deviation of 1.6% (n = 14). Instrument precision was determined and found to have an average relative standard deviation of 1.0% (n = 16). In addition, analysis precision by the EDXRF method was compared to that for titration and autoanalyzer methodologies and found to be statistically comparable. The sample precision had an averaged relative standard deviation of 2.7% (n = 16) by X-ray methodology. The advantages of this EDXRF method Include Increased sample throughput with excellent precision and accuracy, no solvent usage, and automated data handling.

Iron Oxide Determination by X-Ray Fluorescence for In-Process Control of Solid Propellant and Premixes

1962 ◽  
Vol 6 ◽  
pp. 422-428
Author(s):  
Reuel E. Lamborn ◽  
Foster J. Sorenson
Keyword(s):  
Iron Oxide ◽  
Standard Deviation ◽  
Process Control ◽  
Relative Standard Deviation ◽  
Iron Content ◽  
Control Point ◽  
Factors Affecting ◽  
X Ray ◽  
Operation Conditions ◽  
Relative Standard

AbstractFinely divided iron oxide is used as a burning-rate catalyst in several solid rocket propellants. The concentration is critical and must be accurately determined as a quality control point before the propeltant is cast in the motor case and cured, in addition to the iron oxide, the propellant used for ignition of the Air Force Minuteman first stage contains a polymeric binder system, a solid oxidizer, and a metal powder. This composition makes it difficult to determine accurately the iron content by wet methods in the time available daring the propellant processing cycle. The use of X-ray fluorescence has been investigated as a means of satisfying the analysis time requirements while meeting the prescribed accuracy of ±1% of the amount of iron oxide present. Procedures for preparing test specimens have been developed and instrument operation conditions chosen which yield satisfactory precision. When ten specimens from each of three premixes were analyzed for iron content, the observed within-mix mean relative standard deviation was 0.28%; for propellant analyzed under the same conditions, the mean relative standard deviation was 0.35%. Factors affecting mix-to-mix accuracy, such as particle size and shape and interelement absorption and enhancement effects, have been investigated. Accuracy is adequate for in-process control of the iron oxide level in the premix, but further work is required before satisfactory control of propellant is achieved.

X-ray Spectrographic Microanalysis of Human Urine for Arsenic

1974 ◽  
Vol 28 (2) ◽  
pp. 165-170 ◽  
Author(s):  
James C. Mathies
Keyword(s):  
Standard Deviation ◽  
Human Body ◽  
Human Urine ◽  
Test Paper ◽  
X Ray ◽  
Paper Disk ◽  
Filter Paper Disk ◽  
Relative Standard ◽  
Digestion Mixture

A rapid, precise, and interference-free x-ray spectrographic procedure for the determination of arsenic in human body fluids and tissues has been devised. The organic material in the sample is oxidized, and the arsenic is released by a simplified rapid wet-washing technique using nitric-sulfuric-perchloric acids. The arsenic in the digestion mixture is converted to arsine and collected quantitatively on a silver nitrate-impregnated filter paper disk using a new and convenient sub-micro modification of the Gutzeit arsine generator. The arsenic in the test paper is rapidly and nondestructively quantitated to the nearest 0.1 µg in the x-ray spectrograph. The method is relatively free of the interferences usually associated with Gutzeit and colorimetric techniques for arsenic. The precision of the method is indicated by the fact that 5 µg of arsenic can be quantitated with a relative standard deviation of 2.5% or less. Normal levels of arsenic in human urine have been redetermined.

scholarly journals Mechanical Properties of Flexible TPU-Based 3D Printed Lattice Structures: Role of Lattice Cut Direction and Architecture

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2986
Author(s):  
Victor Beloshenko ◽  
Yan Beygelzimer ◽  
Vyacheslav Chishko ◽  
Bogdan Savchenko ◽  
Nadiya Sova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lattice Structure ◽  
Pore Space ◽  
Thermoplastic Polyurethane ◽  
Bending Tests ◽  
Three Point Bending ◽  
Lattice Materials ◽  
3D Printed ◽  
Anisotropy Of Mechanical Properties

This study addresses the mechanical behavior of lattice materials based on flexible thermoplastic polyurethane (TPU) with honeycomb and gyroid architecture fabricated by 3D printing. Tensile, compression, and three-point bending tests were chosen as mechanical testing methods. The honeycomb architecture was found to provide higher values of rigidity (by 30%), strength (by 25%), plasticity (by 18%), and energy absorption (by 42%) of the flexible TPU lattice compared to the gyroid architecture. The strain recovery is better in the case of gyroid architecture (residual strain of 46% vs. 31%). TPUs with honeycomb architecture are characterized by anisotropy of mechanical properties in tensile and three-point bending tests. The obtained results are explained by the peculiarities of the lattice structure at meso- and macroscopic level and by the role of the pore space.

scholarly journals Quantitative mass spectrometry imaging of drugs and metabolites: a multiplatform comparison

2021 ◽  
Vol 413 (10) ◽  
pp. 2779-2791
Author(s):  
Lieke Lamont ◽  
Darya Hadavi ◽  
Brent Viehmann ◽  
Bryn Flinders ◽  
Ron M. A. Heeren ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Mass Spectrometry Imaging ◽  
Pharmaceutical Compounds ◽  
Quantitative Mass Spectrometry ◽  
Tissue Model ◽  
Drug Candidates ◽  
Relative Standard ◽  
3D Printed

AbstractMass spectrometry imaging (MSI) provides insight into the molecular distribution of a broad range of compounds and, therefore, is frequently applied in the pharmaceutical industry. Pharmacokinetic and toxicological studies deploy MSI to localize potential drugs and their metabolites in biological tissues but currently require other analytical tools to quantify these pharmaceutical compounds in the same tissues. Quantitative mass spectrometry imaging (Q-MSI) is a field with challenges due to the high biological variability in samples combined with the limited sample cleanup and separation strategies available prior to MSI. In consequence, more selectivity in MSI instruments is required. This can be provided by multiple reaction monitoring (MRM) which uses specific precursor ion-product ion transitions. This targeted approach is in particular suitable for pharmaceutical compounds because their molecular identity is known prior to analysis. In this work, we compared different analytical platforms to assess the performance of MRM detection compared to other MS instruments/MS modes used in a Q-MSI workflow for two drug candidates (A and B). Limit of detection (LOD), linearity, and precision and accuracy of high and low quality control (QC) samples were compared between MS instruments/modes. MRM mode on a triple quadrupole mass spectrometer (QqQ) provided the best overall performance with the following results for compounds A and B: LOD 35.5 and 2.5 μg/g tissue, R2 0.97 and 0.98 linearity, relative standard deviation QC <13.6%, and 97–112% accuracy. Other MS modes resulted in LOD 6.7–569.4 and 2.6–119.1 μg/g tissue, R2 0.86–0.98 and 0.86–0.98 linearity, relative standard deviation QC < 19.4 and < 37.5%, and 70–356% and 64–398% accuracy for drug candidates A and B, respectively. In addition, we propose an optimized 3D printed mimetic tissue model to increase the overall analytical throughput of our approach for large animal studies. The MRM imaging platform was applied as proof-of-principle for quantitative detection of drug candidates A and B in four dog livers and compared to LC-MS. The Q-MSI concentrations differed <3.5 times with the concentrations observed by LC-MS. Our presented MRM-based Q-MSI approach provides a more selective and high-throughput analytical platform due to MRM specificity combined with an optimized 3D printed mimetic tissue model. Graphical abstract

scholarly journals Determination of the Mineral Composition of the Lake Bottom Sediments by X-Ray Diffraction Method and Physico-Chemical Modelling

2019 ◽  
pp. 382-394
Author(s):  
Roman V. Smelyy ◽  
Ekaterina V. Kaneva ◽  
Anastasiya V. Oshchepkova ◽  
Valerii A. Bychinskii ◽  
Tat’yana S. Aisueva ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Mineral Composition ◽  
Bottom Sediments ◽  
Diffraction Method ◽  
Least Square ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Standard ◽  
Lake Bottom ◽  
Lake Bottom Sediments

The paper reports comparison of three approaches to define the contents of minerals and mineral groups in the carbonate-silicate lake bottom sediments. The two approaches are based on the method of X-ray powder diffraction. The first one treats with the Rietveld Method in the software DIFFRAC Plus diffractometer D8 Advance (PDF-2 database). The second one uses the method of reference intensities (corundum ratios) and optimization of the model powder patterns from the X-ray phase standards of PDF-2 database and equations of the element balance with regularization of the least square functional. The third approach of physic-chemical modeling selects probable single mineral and multi-component phases through modelling the sold solutions, and it uses the data on the element composition obtained by XRF technique, as well as the data of X-ray diffraction on the qualitative mineral composition. Thirty samples of bottom sediment cores taken in the Zun-Torey Lake in East Siberia were analyzed by the three approaches described herein. The contents of mineral groups (feldspars, quartz, clay minerals and carbonates) varied within the range 10-40 mass %. The discrepancies between obtained results show the standard deviation ranging from 2 to 9 mass %. A relative standard deviation commonly provides the value below 30 %, so such determinations could be considered quantitative ones. With regard to the acquired data, it is hard to prefer this or that approach. Available data was employed to assess the error of X-ray phase powder analysis in measuring the abundance of mineral groups in the carbonate-silicate sedimentary rocks in the absence of reference materials to compare with certified mineral composition

scholarly journals Infill Designs for 3D-Printed Shape-Memory Objects

Technologies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 29
Author(s):  
Daniel Koske ◽  
Andrea Ehrmann
Keyword(s):  
Shape Memory ◽  
Low Temperatures ◽  
Shape Memory Polymers ◽  
Poly Lactic Acid ◽  
Protective Equipment ◽  
Bending Tests ◽  
Three Point Bending ◽  
Long Time ◽  
3D Printed ◽  
Recovery Cycles

Shape-memory polymers (SMPs) can be deformed, cooled down, keeping their new shape for a long time, and recovered into their original shape after being heated above the glass or melting temperature again. Some SMPs, such as poly(lactic acid) (PLA), can be 3D printed, enabling a combination of 3D-printed shapes and 2D-printed, 3D-deformed ones. While deformation at high temperatures can be used, e.g., to fit orthoses to patients, SMPs used in protective equipment, bumpers, etc., are deformed at low temperatures, possibly causing irreversible breaks. Here, we compare different typical infill patterns, offered by common slicing software, with self-designed infill structures. Three-point bending tests were performed until maximum deflection as well as until the maximum force was reached, and then the samples were recovered in a warm water bath and tested again. The results show a severe influence of the infill pattern as well as the printing orientation on the amount of broken bonds and thus the mechanical properties after up to ten test/recovery cycles.

An Automated Procedure for the Determination of Ammonia in Tobacco

1972 ◽  
Vol 6 (4) ◽  
Author(s):  
P.F. Collins ◽  
W.W. Lawrence ◽  
J.F. Williams
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Distillation Method ◽  
Relative Standard ◽  
Tobacco Sample ◽  
Automated Determination

AbstractA procedure for the automated determination of ammonia in tobacco has been developed. Ammonia is extracted from the ground tobacco sample with water and is determined with a Technicon Auto Analyser system which employs separation of the ammonia through volatilization followed by colourimetry using the phenate-hypochlorite reaction. The procedure has been applied to a variety of tobaccos containing from 0.02 to 0.5 % ammonia with an overall relative standard deviation of 2 %. The accuracy of the procedure as judged by recovery tests and by comparison to a manual distillation method is considered adequate

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