Study on the Optimization of Process Parameters for Absorbable Bone Plate with In-Mold Heat Treatment

2019 ◽  
Vol 294 ◽  
pp. 71-76
Author(s):  
Wen Teng Wang ◽  
Yu Chen Lin
Keyword(s):  
Heat Treatment ◽  
Process Parameters ◽  
Bone Fracture ◽  
Fracture Fixation ◽  
Metal Ion ◽  
Treatment Time ◽  
Bone Screws ◽  
Bone Plates ◽  
Melt Temperature ◽  
Metal Ion Release

Titanium alloy & stainless steel are major materials for bone fracture fixation such as bone screws and plates in today's medical devices. However, the fixation devices made of metal not only have the risk of metal ion release to cause human allergies, but they also need to be removed by a second surgical operation making pain and the risk of the patient’s wound infection after the bone fracture healing. The biodegradable Polylactic Acid (PLA) bone screws & bone plates have the great advantage of not needing a second operation, but their insufficient strengths make them not be widely used in the current bone fracture fixation. In the study, we use PLA as the matrix and in-mod heat treatment with induction coils to increase the strength of bone screw & plate by improving crystallinity of material. Regarding ASTM F2502 “Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants”, we measure bending loads of test pieces before and after in-mold heat treatment, and obtain the optimized process parameters by Taguchi method that will increase the bend load of PLA bone plates by 34.82%. These optimal parameters are the injection speed of 80 mm/s, the melt temperature of 205 °C, the heat treatment temperature of 110 °C and heat treatment time of 20 min.

Assessing the Feasibility of a Nailing Operation for Bone Fracture Fixation Using a Cavity-Expansion Based Penetration Model

2010 ◽  
Author(s):  
Matthew P. Prygoski ◽  
Steven R. Schmid
Keyword(s):  
Bone Fracture ◽  
Fracture Fixation ◽  
Bone Screws ◽  
Cavity Expansion ◽  
Bone Fragments ◽  
Fixation Plate

After a bone is fractured the two bone segments must be realigned and fixated so that proper healing can occur. It is beneficial and often necessary to also fixate any bone fragments that may have formed during the injury. Traditionally a fracture fixation plate must be inserted using bone screws to hold the bone segments together. Any additional fragments must be attached using screws, bone pins, or wires. Each fracture, especially when complex in nature, may require a unique set of hardware to achieve proper fixation. Proper planning by a skilled surgeon is usually necessary. Insertion of these implants may also be rather invasive since the devices must be inserted into incisions at least as large as the device itself. All of these factors increase the duration of the surgery.

Disintegration of sewage sludge with bifrequency ultrasonic treatment

2009 ◽  
Vol 60 (6) ◽  
pp. 1445-1453 ◽  
Author(s):  
Jianguo Jiang ◽  
Shihui Yang ◽  
Maozhe Chen ◽  
Qunfang Zhang
Keyword(s):  
Sewage Sludge ◽  
Ultrasonic Treatment ◽  
Metal Ion ◽  
Treatment Time ◽  
Oxygen Demand ◽  
High Energy ◽  
Single Frequency ◽  
Ultrasonic Frequency ◽  
Ion Release ◽  
Metal Ion Release

A bifrequency ultrasonic generating trough was used to improve disintegration of sewage sludge from thickener tanks. Ultrasonic operating parameters such as frequency, power, and time were optimized. Ultrasonic treatment successfully disintegrated the floc structure of sewage sludge and promoted the release of organic matter and metal ions such as Ca2 +  and Mg2 + . After ultrasonic treatment, soluble chemical oxygen demand (SCOD) in the sludge solution increased 11.28–49.06%, while the concentrations of Ca2 +  and Mg2 +  rose 5.5–25.0% and 2.7–19.0%, respectively. The ultrasonic frequency of 25 kHz was most effective in disintegrating sludge, and high energy densities and longer treatment time increased SCOD and metal ion release. The optimal parameters that promoted the increase SCOD were 25 kHz, 75 W/L and 60 s. Under these conditions, double-frequency ultrasonication was more effective than single-frequency ultrasonication.

scholarly journals High Voltage Electric Discharge for Recovery of Chlorogenic Acid from Tobacco Waste

2021 ◽  
Vol 13 (8) ◽  
pp. 4481
Author(s):  
Marija Banožić ◽  
Antun Jozinović ◽  
Jovana Grgić ◽  
Borislav Miličević ◽  
Stela Jokić
Keyword(s):  
Chlorogenic Acid ◽  
Process Parameters ◽  
Electric Discharge ◽  
High Voltage ◽  
Treatment Time ◽  
Strong Dependence ◽  
Extraction Procedure ◽  
Polynomial Equation ◽  
Experimental Conditions ◽  
Tobacco Waste

Three fractions of tobacco waste (scrap, dust and midrib) were subjected to a high voltage electric discharge (HVED) assisted extraction procedure under different experimental conditions: solvent:solid ratio (300, 500, 700 mL/g), frequency (40, 70, 100 Hz) and treatment time (15, 30, 45 min), in order to study the influence of these conditions on the content of chlorogenic acid. The content of chlorogenic acid ranged from 1.54 to 3.66 mg/100 g for scrap, from 1.90 to 2.97 mg/100 g for dust, and from 2.30 to 3.38 mg/100 g for midrib extract, showing a strong dependence on the applied process parameters. The temperature change and the change in pH and electrical conductivity of the extracts after high voltage discharge treatment were also observed. The studied process parameters showed a statistically significant effect on the chemical and physical properties of the extracts from tobacco waste as well as on the content of chlorogenic acid, indicating the potential of HVED assisted processes in the separation of chlorogenic acid from tobacco industry waste. Multiple regression analysis was used to fit the results for the chlorogenic acid to a second order polynomial equation and the optimum conditions were determined.

scholarly journals Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4102
Author(s):  
Jan Stindt ◽  
Patrick Forman ◽  
Peter Mark
Keyword(s):  
Heat Treatment ◽  
High Performance ◽  
High Performance Concrete ◽  
Treatment Time ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Shrinkage Strain ◽  
Temperature Treatment ◽  
Production Flow ◽  
Steel Fibres

Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres.

scholarly journals Bioactive Plasma Coatings on Orthodontic Brackets: In Vitro Metal Ion Release and Cytotoxicity

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 857
Author(s):  
Lasni Samalka Kumarasinghe ◽  
Neethu Ninan ◽  
Panthihage Ruvini Lakshika Dabare ◽  
Alex Cavallaro ◽  
Esma J. Doğramacı ◽  
...  
Keyword(s):  
Metal Ion ◽  
Prolonged Exposure ◽  
Orthodontic Brackets ◽  
Plasma Polymer ◽  
Functional Coatings ◽  
Key Factors ◽  
Ion Release ◽  
Metal Ion Release ◽  
Surface Functionalisation

The metal ion release characteristics and biocompatibility of meta-based materials are key factors that influence their use in orthodontics. Although stainless steel-based alloys have gained much interest and use due to their mechanical properties and cost, they are prone to localised attack after prolonged exposure to the hostile oral environment. Metal ions may induce cellular toxicity at high dosages. To circumvent these issues, orthodontic brackets were coated with a functional nano-thin layer of plasma polymer and further immobilised with enantiomers of tryptophan. Analysis of the physicochemical properties confirmed the presence of functional coatings on the surface of the brackets. The quantification of metal ion release using mass spectrometry proved that plasma functionalisation could minimise metal ion release from orthodontic brackets. Furthermore, the biocompatibility of the brackets has been improved after functionalisation. These findings demonstrate that plasma polymer facilitated surface functionalisation of orthodontic brackets is a promising approach to reducing metal toxicity without impacting their bulk properties.

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