Titanium Wire Research Articles

Investigation on titanium wire melting through high-frequency induction heating for additive manufacturing process

ABSTRACT A high-frequency induction heating (HFIH) system is a novel and clean heat source that can potentially melt high melting point material to develop the wire feed-based additive manufacturing (AM) process. The present study establishes the optimised coil parameters, including coil geometry for melting the titanium wire using induction heating. A fully coupled electromagnetic-thermal-fluid flow model is established to analyse the temperature profile of the wire. The wire feed velocity (0.012 m/s) is incorporated in the coupled model using the deformed mesh method. Optimised wire diameter and coil parameters, such as a three-turn helical coil with a circular cross-section, coil turn spacing of 1.5 mm, and a coupling distance of 4 mm, melt the 3.6 mm titanium wire rapidly and create the molten droplet. The results suggest that the optimised coil parameters improve the magnetic flux density, which enhances joule heating in the wire. However, the conical-spiral coil geometry of the three-turn fails to melt the wire completely. In contrast, the helical coil of the three-turn melts the wire completely. The maximum velocity of the molten metal is found as 0.25 m/s. Effectively, the heat transfer and material flow analysis drives to develop the potential additive manufacturing system.

An All-Solid-State Ti/RuOx pH Electrode Prepared Based on the Thermal Oxidation Method.

The development of all-solid-state precise pH electrodes holds significant importance in various fields, particularly in marine scientific research. To achieve this goal, we proposed a novel fabrication technique for an all-solid-state ruthenium oxide (Ti/RuOx) pH electrode. We thin-coated the RuCl3 precursor solution on a titanium wire substrate using a heat gun repeatedly and then calcined it in a mixture of Li2CO3 and Na2O2 at 400 °C to obtain a ruthenium oxide (RuOx) film. This RuOx film was subjected to acid treatment with dilute nitric acid, and a polytetrafluoroethylene heat shrink tube was wrapped around the non-RuOx film area. Finally, the RuOx film was fully immersed in a pH 4.00 buffer solution, finalizing the electrode preparation. The RuOx film exhibits a dense and regular conical morphology. The Ti/RuOx electrode demonstrates a good near-Nernstian response slope (e.g., -59.04 mV/pH at 25 °C), high linearity (e.g., R2 = 0.9999), rapid response (<1 s), low hysteresis (<3 mV), excellent reversibility, and good repeatability in the pH range of 2.00-10.00. After full hydration, the Ti/RuOx electrode shows a potential drift of 8.5 mV and a drift rate of approximately 0.27 mV/day over a period of 25 days, indicating good long-term stability. Furthermore, the Ti/RuOx electrode exhibits robust resistance against interference from various ions and low-concentration redox substances, ensuring a long storage life (at least 280 days), and high measurement accuracy (e.g., ± 0.02 pH units) for diverse water samples, including seawater, freshwater, and tap water. This study has evaluated the potential of the Ti/RuOx electrode as a reliable and accurate tool for pH measurements in marine scientific applications.

Efficiency of clear aligners with nickel titanium wires for treating mandibular incisor crowding.

Patients who are allergic to nickel, which is present in stainless steel brackets and wires, commonly utilise clear aligners. The objective of this research was to compare the management of mandibular incisor crowding with nickel titanium (NiTi) wires and clear aligners. A random division of forty participants into two groups of twenty samples each was made. Participants in group B received transparent aligners, whereas those in group A received NiTi arch wires. We assessed malocclusion using Little's irregularity index. A survey instrument was utilised to document the degree of discomfort. Patients were routinely recalled every one, two, and three months. The mean score for groups A and B was 2.86 mm and 2.88 mm at baseline, 1.71 mm and 1.52 mm at one month, 1.02 mm and 1.23 mm at two months, and 0.72 mm and 0.48 mm at three months, respectively. The difference wasn't that big (p > 0.05). In groups A and B, the mean change in Little's irregularity index score was 1.19 mm and 1.21 mm at one month, 0.55 mm and 0.51 mm at two months, and 0.26 mm and 0.45 mm at three months, respectively. The difference wasn't that big (p > 0.05). For groups A and B, the corresponding mean discomfort scores were 2.6 and 2.3 at baseline, 2.2 and 1.8 after one month, 1.6 and 1.5 at two months, and 1.1 and 0.9 at three months. Since p > 0.05, the difference was not significant. The results of this study showed that NiTi wires and clear aligners worked just as well to treat cases of mandibular anterior crowding.

Evaluation of the effect of osteosynthesis wires on the structural reorganization of metaepiphyseal cartilage (an experimental and morphological study)

Introduction Premature arrest of bone growth is the most common complication of bone fractures at the growth plate level.The purpose of the work was to evaluate the structural reorganization of metaepiphyseal cartilage following its direct injury with metal and biodegradable wires in an experiment.Materials and methods The metaepiphyseal cartilage of the distal femur of 18 lambs of both sexes was studied. The age of the animals at the beginning of the study was (43.92 ± 0.8) days, by 60 and 120 days (102.63 ± 0.82) and (161.1 ± 0.9) days, respectively. The animals underwent transphyseal insertion of wires/ pins: series 1 — Kirschner wires, series 2 — titanium wires, series 3 — poly-L-lactic acid pins. The duration of the experiment was 60 and 120 days. Clinical and radiographic studies were carried out. Histomorphometry was performed using an AxioScope.A1 microscope and Zenblue software (CarlZeissMicroImagingGmbH, Germany).Results Reactive changes in the growth plate at the interface with the wire were manifested by proliferation of chondrocytes in the zone of proliferating cartilage and in the reserve zone; the minimally expressed changes were noted in series 2, the most pronounced were in series 1. By the end of the experiment, at the interface with the wire in series 1, blood vessels penetrated into the metaepiphyseal cartilage; in series 3 the amount of the fibrous component was increased, which indicates further formation of “bone bridges” and “fibrous bridges,” respectively. In undamaged areas of the growth plate in all series, the zonal structure was preserved. By the end of the experiment, increased values of the thickness of the metaepiphyseal cartilage were noted (1.2 times higher than the control), differences between series were a tendency; in series 2 and 3 the ratio of metaepiphyseal cartilage zones was comparable to the control; in series 1 the proportion of the proliferating cartilage zone was increased by 4 %.Discussion The main problem with growth plate injuries is the formation of bone tissue or fibrosis, which affects the growing process. Currently, the question of choosing a treatment tactic for growth plate injury depending on the size of the “bone bridges” is debatable. Relevant are future comparative studies of the regeneration of metaepiphyseal cartilage defects after the use of fixators made from different materials.Conclusion Histomorphometric characteristics of the growth zone reliably showed that the insertion of wires, regardless of their material, was not accompanied by inhibition of the bone-forming function of the distal metaepiphyseal cartilage of the femur.

Impact of recycling on efficiency and efficacy of copper nickel titanium wire and heat activated nickel titanium wire – An invitro study

The aim of the study is to assess the feasibility of reusing copper nickel titanium wire and heat activated nickel titanium wires by evaluating the changes in efficiency and efficacy of wire after different sterilization techniques. 120 total samples were taken. 60 samples of Damon copper nickel titanium (ORMCOTM) and 60 samples of heat activated nickel titanium wires (ORMCOTM). Damon CuNiTi and HANT were divided in 4 different sub groups of 15 samples each. 15 as received wires served as controlled group. The remaining wires were placed intraorally for a period of 4 weeks in patients undergoing orthodontic treatment. After 4 weeks, these wires were taken out. Remaining 45 wires were divided on the basis of sterilization method to be used. (autoclave, 70% isopropyl alcohol, 2% glutaraldehyde solution). Maximum load and tensile strength were tested using universal testing machine. No significant difference in mechanical properties of wires after various sterilization process (p value &amp;#62; 0.05). There no such difference in mechanical properties of controlled group wires and wires those are placed intraorally for 4 weeks. Results suggested that there was no statistically significant difference in the Ultimate Tensile Strength and Maximum Load of Damon Copper Nickel-Titanium wire and Heat Activated Nickel Titanium wire following various sterilization procedures. These wires can be reused after sterilization.

HOCl Production Modelling for an Electrochemical Catheter

Intravascular catheters are used in critically ill patients to deliver fluids and lifesaving medications, and for hemodynamic monitoring. These catheters are at risk for infection, especially when in place for prolonged periods of time. The management of catheter-related infections are challenged by both the presence of biofilms and the frequent association with multidrug-resistant organisms. Efforts to mitigate central line-associated bloodstream infections (CLABSIs) have focused on preventive measures. Several strategies to prevent intraluminally sourced CLABSI have been developed and used, including antimicrobial agent locks and antimicrobial-impregnated catheter lumens. Although antimicrobial locks have reduced CLABSI rates, this strategy is prone to complications, including resistance selection, allergic reactions, catheter damage, and host toxicity due to the high concentrations of agents needed. Largely because of these factors, antimicrobial locks are infrequently used for CLABSI prevention in clinical practice. Antimicrobial impregnated catheter lumens have also shown variable effects against CLABSI and are likewise not regularly used. Therefore. innovative therapeutic solutions are necessary, especially those that allow catheter retention. In this context, the integration of electrochemical technologies for hypochlorous acid (HOCl) production within intravascular catheters emerges as a promising strategy to combat CLABSIs. HOCl is a strong oxidizing agent that damages microbial cells by interacting with lipids, nucleic acids, sulfur-containing amino acids, and membrane components. It is found in all mammals as an endogenous substance produced by the immune system to protect the body from pathogens. In this study, electrochemical generation of HOCl in an electrochemical catheter (e-catheter) was simulated using a model called Electrochemical Hypochlorous Acid Production (EHAP), implemented in COMSOL Multiphysics®. The e-catheter has two components, a hub and a tube, both filled with 0.9% saline solution. Titanium wires are used as working and counter electrodes.The model was used to define critical variables that may impact HOCl generation and distribution. In addition to predicting HOCl concentrations, the EHAP model was used to monitor effects of 1) a waiting period after constant polarization, 2) operational voltage, 3) working electrode length and 4) working electrode surface area. Findings using the EHAP model revealed the following: 1) Diffusion limitations predominate when the electrodes are localized to the hub, yielding a lower HOCl concentration in the tube compared to the hub. Increasing the voltage between the working and the reference electrodes increases HOCl generation, however concentrations are not enough to deliver HOCl to the tube. 2) HOCl concentrations are higher in the tube compared to hub when the working electrode extends the entire length of the tube. 3) HOCl concentration distributions can be tuned by changing the surface area of the working electrode within different compartments of the e-catheter.

Napthalimide-based nuclease inhibitor: A multifunctional therapeutic material to bolster MRSA uptake by macrophage-like cells and mitigate pathogen adhesion on orthopaedic implant

The healthcare burden rendered by methicillin-resistant Staphylococcus aureus (MRSA) warrants the development of therapeutics that offer a distinct benefit in the clinics as compared to conventional antibiotics. The present study describes the potential of napthalimide-based synthetic ligands (C1-C3) as inhibitors of the staphylococcal nuclease known as micrococcal nuclease (MNase), a key virulence factor of the pathogen. Amongst the ligands, the most potent MNase inhibitor C1 rendered non-competitive inhibition, reduced MNase turnover number (Kcat) and catalytic efficiency (Kcat/Km) with an IC50 value of ~950 nM. CD spectroscopy suggested distortion of MNase conformation in presence of C1. Flow cytometry and confocal microscopy indicated that C1 restored the ability of activated THP-1 cells to engulf DNA-entrapped MRSA cells. Interestingly, C1 could inhibit MRSA adhesion onto collagen. For potential application, C1-loaded pluronic F-127 micellar nanocarrier (C1-PMC) was generated, wherein the anti-adhesion activity of the pluronic carrier (PMC) and C1 was harnessed in tandem to deter MRSA cell adhesion onto collagen. MRSA biofilm formation was hindered on C1-PMC-coated titanium (Ti) wire, while eluates from C1-PMC-coated Ti wires were non-toxic to HEK 293, MG-63 and THP-1 cells. The multifunctional C1 provides a blueprint for designing therapeutic materials that hold translational potential for mitigation of MRSA infections.

The Micromechanical Properties and Surface Roughness of Orthodontic Retainer Wires-An In Vitro Analysis.

Despite the large variety of retainer wires available, no studies could be found comparing the micromechanical properties and surface roughness of different retainer wires. Such characteristics affect the survival of the fixed retainer in terms of both fracture resistance and resistance to debonding from the tooth. Therefore, the aim of the present study was to examine and compare those characteristics in popular retainer wires. six different popular orthodontic retainer wires were subjected to instrumental indentation based on the Oliver and Pharr method. The geometric surface structure was analysed using a non-contact profilometer. stainless steel wires had a higher hardness and a higher elastic modulus compared to titanium wires and white gold chain. The titanium wire and the white gold chain showed much more roughness than other wires. stainless steel wires are the most resistant, considering both the shape retention capacity and the ability to resist abrasive wear. The titanium wire showed the lowest hardness and, thus, the highest susceptibility to deformation. Bond-a-braid, Retainium and Orthoflex white gold are more resistant to fracture than other steel wires. Titanium wire and chain retainer wires have more roughness, which is a great advantage in terms of mechanical adhesion to composite materials.

Heating of metallic orthodontic devices during anti-aging treatment with vacuum and electromagnetic fields: In vitro study.

The physical appearance of an individual plays a primary role as it influences the opinion of the viewer. For this reason, orthodontic therapy to improve perceived aesthetics is in high demand among patients. This factor, combined with the increase in the number of non-invasive facial aesthetic treatments, has led to the need to understand potential risk factors in the application of medical devices to the perioral skin in patients with fixed orthodontic appliances. The aim of this study was to evaluate in vitro heating of the orthodontic bracket following electromagnetic fields and negative pressure (V-EMF) used as an anti-aging treatment. Two different types of titanium alloy wires, one made of "beta-Titanium" alloy and the other "Ni-Ti" (DW Lingual Systems GmbH-Bad Essen-Germany) were used. The orthodontic wires and brackets mounted on a resin mouth were covered with porcine muscle tissue, then subjected to anti-aging therapy with a Bi-one LifeTouchTherapy medical device (Expo Italia Srl-Florence-Italy) which generates a combination of vacuum and electromagnetic fields (V-EMF) already adopted for antiaging therapy. During administration of the therapy, the orthodontic brackets and porcine tissue were thermally monitored using a Wavetek Materman TMD90 thermal probe (Willtek Communications GmbH-Germany). In total 20 orthodontic mouths were used, 10 with Beta Titanium wires and 10 with Nickel Titanium wires. A temperature increase of about 1°C was recorded in each group. The outcome of the present research shows that the absolute temperatures measured on orthodontic appliances, which, despite having a slightly different curve, both show an increase in temperature of 1.1°C at the end of the session, thus falling well within the safety range of 2°C as specified by the standard CENELEC EN 45502-1. Therefore, V-EMF therapy can be considered safe for the entire dental system and for metal prostheses, which tend to heat up at most as much as biological tissue (+0.9°C/1.1°C vs. 1.1°C/1.1°C). In conclusion, anti-aging therapy with V-EMF causes a thermal increase on orthodontic brackets that is not harmful to pulp health.

Chemical bonding of cross-linked glutaraldehyde/chitosan on the surface of a titanium wire to prepare a robust biocompatible SPME fiber for analysis of phytohormones in plants

A robust biocompatible solid-phase microextraction (SPME) fiber, so-called Ti/APTS/GA/CS, was prepared by chemical bonding of cross-linked glutaraldehyde-chitosan to the surface of a titanium wire using APTS. The fiber was applied for sampling of phytohormones in plant tissues, followed by HPLC-UV analysis. The structure and morphology of the fiber coating was investigated by FT-IR, SEM, EDX, XRD, and TGA techniques. A Box-Behnken design was implemented to optimize the experimental variables. The calibration graphs were linear over a wide linear range (0.5–200 μg L−1) with LODs over the range of 0.01–0.06 μg L−1. The intra-day and inter-day precisions were found to be 1.3–6.3% and 4.3–7.3%, respectively. The matrix effect values ranged from 86.5% to 111.7%, indicating that the complex sample matrices had an insignificant effect on the determination of phytohormones. The fiber was successfully employed for the direct-immersion SPME (DI-SPME-HPLC) analysis of the phytohormones in cucumber, tomato, date palm, and calendula samples.

Evaluation of Thermomechanical Properties in a 2D Rotational Elastocaloric Prototype: A Numerical Study for Enhanced Energy Efficiency

So far, much of the research on the caloric effect has focused on the magnetocaloric effect, which was the first investigated chronologically, in the field of room temperature for about 40 years. Subsequently and especially in the last decade, scientific research has focused on the development of solid-state technologies other than the magnetocaloric one, including the one of interest for this work: elastocaloric technology. This work is part of the “SUSSTAINEBLE” project of the Department of Industrial Engineering at the University Federico II of Naples, aimed at developing the first Italian prototype of an elastocaloric device for environmental conditioning. The prototype is currently in the experimental development phase and its design and construction are dynamically accompanied by a two-dimensional numerical model that fully reproduces its thermo-fluid dynamic operation. The rotary-type prototype consists of 600 Nickel Titanium wires subjected to loading and unloading phases controlled by a properly programmed optical encoder. The thermo-fluidic medium that regulates heat transfer is air. The aim is to characterize the operation of the elastocaloric device using numerical analysis software in order to optimize its geometric, operational, and environmental parameters, to maximize its energy performance in terms of temperature difference, useful thermal power, and coefficient of performance.

In Situ Lubrication in Forging of Pure Titanium Using Carbon Supersaturated Die Materials.

A new solid lubrication method was proposed for dry forging of pure titanium with high reduction in thickness. A free-carbon tribofilm was formed in situ at the hot spots on the contact interface to protect the die surfaces from severe adhesion of work materials. This film consisted of the free carbon, which isolated from the carbon supersaturated die substrate materials, diffused to the contact interface and agglomerated to a thin film. Two different routes of carbon supersaturation process were developed to prepare carbon supersaturated ceramic and metal dies for the dry forging of pure titanium wires. A pure titanium bar was utilized as an easy-to-adherent work material for upsetting in dry and cold. The round bar was upset up to 70% in reduction in thickness with a low friction coefficient from 0.05 to 0.1 in a single stroke. Work hardening was suppressed by this low friction. SEM-EDX, EBSD and Raman spectroscopy were utilized to analyze the contact interface and to understand the role of in situ formed free-carbon films on the low friction and low work hardening during forging. Precise nanostructure analyses were utilized to describe low friction forging behavior commonly observed in these two processes. The in situ solid lubrication mechanism is discussed based on the equivalence between the nitrogen and carbon supersaturation processes.

Mechanical and Computational Fluid Dynamic Models for Magnesium-Based Implants.

Today, mechanical properties and fluid flow dynamic analysis are considered to be two of the most important steps in implant design for bone tissue engineering. The mechanical behavior is characterized by Young's modulus, which must have a value close to that of the human bone, while from the fluid dynamics point of view, the implant permeability and wall shear stress are two parameters directly linked to cell growth, adhesion, and proliferation. In this study, we proposed two simple geometries with a three-dimensional pore network dedicated to a manufacturing route based on a titanium wire waving procedure used as an intermediary step for Mg-based implant fabrication. Implant deformation under different static loads, von Mises stresses, and safety factors were investigated using finite element analysis. The implant permeability was computed based on Darcy's law following computational fluid dynamic simulations and, based on the pressure drop, was numerically estimated. It was concluded that both models exhibited a permeability close to the human trabecular bone and reduced wall shear stresses within the biological range. As a general finding, the proposed geometries could be useful in orthopedics for bone defect treatment based on numerical analyses because they mimic the trabecular bone properties.

Prototype of Low-Cost Microvascular Clips for Laboratory Use

Vascular neurosurgical procedures require temporary or permanent surgical clips to treat cerebral aneurysms, arteriovenous malformations, or bypass surgery. In this scenario, surgical clips should have specific characteristics such as high-quality material, proper design, closing force, and biocompatibility. Due to these characteristics, the price of these clips does not allow their availability at the experimental surgery laboratory worldwide. We describe here the technique for manufacturing handcrafted clips of low cost, using dental stainless steel or titanium wire of 0.18mm, 0.20mm, or 0.22mm in diameter. We must complete six steps to obtain the clip using our hands and small electrician needle nose pliers for wire molding. These clips have a closing force of 30-60 gr/cm2 (depending on the wire diameter). They can be used in the experimental surgery laboratory to clip arteries or veins during vascular microsurgery procedures. Also, they can be used as temporary clips with confidence in low-flow bypass (v.gr. superficial temporal artery to middle cerebral artery or occipital artery to posterior inferior cerebellar artery anastomoses). Making practical low-cost clips for use in laboratory procedures or during low-flow anastomosis as temporary clips is possible. The main advantages are the low cost and the worldwide availability of the basic materials. The main disadvantage is the learning curve to get the ability to master the manufacturing of these clips.

Load Deflection Characteristics of Orthodontic Gummetal® Wires in Comparison with Nickel-Titanium Wires: An In Vitro Study.

The aim of this study was to investigate the load deflection characteristics of Gummetal® wires in comparison to nickel-titanium (NiTi) wires. Four different NiTi wires and one Gummetal® archwire were analyzed in two dimensions (0.014″ (0.36 mm) and 0.016″ × 0.022″ (0.41 mm × 0.56 mm)) and in two different orientations (edgewise and ribbonwise) using three-point bending tests at T = 37 °C. Force-displacement curves were recorded and analyzed. The Gummetal® 0.014″ wires exhibited higher forces compared to the NiTi wires at 2.0 mm deflection. At 1.0 mm deflection, the opposite pattern was observed. For the 0.016″ × 0.022″ Gummetal® wires, the forces were within the force interval of the NiTi wires at 2.0 mm deflection. At a deflection of 1.0 mm, no residual force was measurable for the Gummetal® wires. All the NiTi wires investigated showed hysteresis and a superelastic plateau. However, the Gummetal® did not form a plateau, but hysteresis was present. An easier plastic deformability compared to the NiTi wires was observed for all the tested geometries.

A NiO@Ti based linear photoelectrochemical type ultraviolet photodetector

Omnidirectional detection is widely used in optical tracking systems, omni-directional cameras and optical field measurements and so on. However, the planar structures of ultraviolet (UV) photodetectors (PDs) limit their application in omnidirectional detection. In this work, the NiO nanosheets were fabricated on a titanium (Ti) wire substrate by hydrothermal method and then assembled a photoelectrochemical (PEC) type UV photodetector (PD). Under ultraviolet (UV) irradiation of 35 mW cm−2 @ 365 nm, the PD exhibits a stable photocurrent of 1.53 μA cm−2 and repeatable switching cycles. Also, the PD presents fast response and recovery times of 0.074 s and 0.130 s, respectively. Particularly, the PD based on NiO@Ti possesses excellent response for rotation angles in the range from 0° to 360° under UV light irradiation.

An osteoinductive surface by adhesive bone morphogenetic protein-2 prepared using the bioorthogonal approach for tight binding of titanium with bone.

Inorganic biomaterials are used in various orthopedic and dental implants. Nevertheless, they cause clinical issues such as loosening of implants and patient morbidity. Therefore, inspired by mussel adhesive proteins, we aimed to design an adhesive and dimer-forming highly active bone morphogenetic protein-2 (BMP-2) using bioorthogonal chemistry, in which recombinant DNA technology was combined with enzymatic modifications, to achieve long-term osseointegration with titanium. The prepared BMP-2 exhibited substantially higher binding activity than wild-type BMP-2, while the adhered BMP-2 was more active than soluble BMP-2. Therefore, the adhesive BMP-2 was immobilized onto titanium wires and screws and implanted into rat bones, and long-term osteogenesis was evaluated. Adhesive BMP-2 promoted the mechanical binding of titanium to bones, enabling efficient bone regeneration and effective stabilization of implants. Thus, such adhesive biosignaling proteins can be used in regenerative medicine.

Sustainable Recovery of Titanium Alloy: From Waste to Feedstock for Additive Manufacturing

Titanium and its alloys are widely employed in the aerospace industry, and their use will increase in the future. At present, titanium is mainly produced by the Kroll method, but this is expensive and energy-intensive. Therefore, the research of efficient and sustainable methods for its production has become relevant. The present review provides a description of the titanium recycling methods used to produce mostly aeronautical components by additive manufacturing, offering an overview of the actual state of the art in the field. More specifically, this paper illustrates that ilmenite is the main source of titanium and details different metallurgic processes for producing titanium and titanium alloys. The energy consumption required for each production step is also illustrated. An overview of additive manufacturing techniques is provided, along with an analysis of their relative challenges. The main focus of the review is on the current technologies employed for the recycling of swarf. Literature suggests that the most promising ways are the technologies based on severe plastic deformation, such as equal-channel angular pressing, solid-state field-assisted sintering technology-forge, and the Conform process. The latter is becoming established in the field and can replace the actual production of conventional titanium wire. Titanium-recycled powder for additive manufacturing is mainly produced using gas atomization techniques.

Tibial lengthening over a bioactive degradable intramedullary implant: a case report

Introduction Long duration of distraction osteosynthesis remains an unsolved problem. One of the promising ways to stimulate reparative regeneration of bone tissue is the technology of combined osteosynthesis with intramedullary elastic reinforcement with titanium wires coated with hydroxyapatite. A significant drawback of this combined distraction osteosynthesis is the planned removal of intramedullary wires several months after disassembling the Ilizarov apparatus.The purpose of this work is to demonstrate the possibility of stimulating reparative regeneration and reducing the duration of distraction osteosynthesis using an intramedullary degradable implant with bioactive filling.Methods We present the first in clinical practice case of surgical leg lengthening in a female 10-year-old patient using the Ilizarov apparatus an intramedullary degradable implant made of polycaprolactone (PCL) saturated with hydroxyapatite to stimulate reparative regeneration in the tibia. Monthly radiographic monitoring of the process of reparative regeneration of bone tissue was supplemented by computed tomography after disassembling the Ilizarov apparatus.Results The process of lengthening the tibia was accompanied by pronounced formation of a bone “sleeve” around the implant, which was directly connected to the endosteum of the tibia. The density of bone substance in the medullary canal reached 496.6 HU. The cortical layer of the tibia in the elongation zone increased to 4 mm, and its density was equal to 1288.8 HU.Discussion Leg lengthening of 4 cm was achieved along with simultaneous correction of valgus recurvatum bone deformity at IO = 15 days/cm, that is two times shorter than the generally accepted excellent IO in distraction osteosynthesis according to Ilizarov.Conclusions Biodegradable polycaprolactone implants saturated with hydroxyapatite might be not inferior to titanium wires coated with hydroxyapatite in regard to the degree of osteoinduction and do not require repeated surgical intervention to remove them.

CURRENT LEADS FOR RESISTIVE CCCM HEATERS

The article justifies the necessity of taking into account the transient electrical resistance of the welding contact between the titanium current lead and the resistive element of the heater made of carbon-carbon composite material (CCCM) during its manufacturing.&#x0D; Carbon-carbon composite material possesses a unique set of technical characteristics that make it suitable as a structural material for manufacturing resistive heaters operating in the temperature range from 400°C to 2500°C in a vacuum or protective atmosphere. The use of CCCM heaters in the thermal chambers of electrothermal engines to convert electrical energy into thermal energy allows them to be employed for temperature measurement inside the engine's thermal chamber. The utilization of an integrated temperature assessment of the CCCM heater, which relies on the resistance change of the heater with increasing temperature and essentially involves measuring the electrical current passing through the heater, requires ensuring accurate values of both the electrical resistance of the heater itself and the electrical resistance at the point of contact with the current lead.&#x0D; The design of the heater has a particular feature, which is the need to supply electrical current to two lamellas of the resistive element of the CCCM heater, located on one side of the heater. For welding the joints between the titanium wire and the resistive element of the heater, TIG welding with a surface arc in an argon environment was applied, with argon being supplied between the welding point and the non-consumable tungsten electrode.&#x0D; Laboratory tests revealed that detachable connections of the titanium wire to the resistive element of the CCCM heater and separable connections (such as bolts, screws, and wedges) cannot meet the requirements for contact resistance stability for various reasons. Among non-detachable connections, only welded joints demonstrated stable electrical contact resistance characteristics.&#x0D; The electrical resistance of the heater with current leads should be 3.8±0.2 Ohms. The tolerance value for resistance is determined by several factors, including the physical properties of CCCM, the technology of mechanical processing, the method of applying protective coatings, the resistance of the welding joint, and others.&#x0D; During mechanical tests of the welding joint between the titanium wire and the heater, it was observed that the wire detachment from the heater occurs with residues of CCCM and a transitional layer of titanium carbide, which forms during welding and can contribute to additional electrical resistance of the heater. Thermal deformation of the CCCM heater in the welding zone does not occur.&#x0D; The results of the conducted research demonstrate that the installation of titanium current leads by welding increases the resistance value of the resistive element of the CCCM heater due to the chemical reaction between the titanium alloy and the resistive element, leading to the formation of an additional layer of titanium carbide. Therefore, the electrical resistance of the resistive element of the CCCM heater during its manufacturing, before welding two titanium wires for current leads, should be reduced, taking into account the transitional electrical resistance of the two welding contacts.