Titanium Cap Research Articles

Thermal environment impact on HfOx RRAM operation: A nanoscale thermometry and modeling study

As the demand for computing applications capable of processing large datasets increases, there is a growing need for new in-memory computing technologies. Oxide-based resistive random-access memory (RRAM) devices are promising candidates for such applications because of their industry readiness, endurance, and switching ratio. These analog devices, however, suffer from poor linearity and asymmetry in their analog resistance change. Various reports have found that the temperature in RRAM devices increases locally by more than 1000 K during operation. Therefore, temperature control is of paramount importance for controlling their resistance. In this study, scanning thermal microscopy is used to map the temperature of Au/Ti/HfOx/Au devices at a steady power state and to measure temperature dynamics of the top electrode above the filament location during both resistive switching loops and voltage pulsing. These measurements are used to verify the thermal parameters of a multiphysics finite elements model. The model is then used to understand the impact of thermal conductivities and boundary conductances of constituent materials on resistance change during the first reset pulse in RRAM devices. It is found that the resistance change can be reduced significantly when the temperature in the titanium capping layer is reduced. We find that the greatest temperature reduction and, therefore, the lowest resistance change in the device are afforded by capping layers with increased thermal conductivities. This work links thermal properties to the resistance change in RRAM devices, providing critical insights into engineering devices with improved switching dynamics.

Effects of Minocycline Hydrochloride as an Adjuvant Therapy for a Guided Bone Augmentation Procedure in The Rat Calvarium.

This in vivo study reports the influence of minocycline-HCl administration on extra-skeletal bone generation in a Guided Bone Augmentation model, utilizing titanium caps placed on the intact as well as perforated calvaria of rats. The test group was administered 0.5 mg/mL minocycline-HCl with the drinking water, and the amount of bone tissue in the caps was quantified at three time points (4, 8 and 16 weeks). A continuously increased tissue fill was observed in all groups over time. The administration of minocycline-HCl as well as perforation of the calvaria increased this effect, especially with regard to mineralization. The strongest tissue augmentation, with 1.8 times that of the untreated control group, and, at the same time, the most mineralized tissue (2.3× over untreated control), was produced in the combination of both treatments, indicating that systemic administration of minocycline-HCl has an accelerating and enhancing effect on vertical bone augmentation.

Bias history impacts the analog resistance change of HfOx-based neuromorphic synapses

Resistive random-access memory (RRAM) devices have been widely studied for neuromorphic, in-memory computing. One of the most studied RRAM structures consists of a titanium capping layer and a HfOx adaptive oxide. Although these devices show promise in improving neuromorphic circuits, high variability, non-linearity, and asymmetric resistance changes limit their usefulness. Many studies have improved linearity by changing materials in or around the device, the circuitry, or the analog bias conditions. However, the impact of prior biasing conditions on the observed analog resistance change is not well understood. Experimental results in this study demonstrate that prior higher reset voltages used after forming cause a greater resistance change during subsequent identical analog pulsing. A multiphysics finite element model suggests that this greater analog resistance change is due to a higher concentration of oxygen ions stored in the titanium capping layer with increasing magnitude of the reset voltage. This work suggests that local ion concentration variations in the titanium capping layer of just tens of atoms cause significant resistance variation during analog operation.

Interface Engineering Enabled Low Temperature Growth of Magnetic Insulator on Topological Insulator

AbstractCombining topological insulators (TIs) and magnetic materials in heterostructures is crucial for advancing spin‐based electronics. Magnetic insulators (MIs) can be deposited on TIs using the spin‐spray process, which is a unique nonvacuum, low‐temperature growth process. TIs have highly reactive surfaces that oxidize upon exposure to atmosphere, making it challenging to grow spin‐spray ferrites on TIs. In this work, it is demonstrated that a thin titanium capping layer on TI, followed by oxidation in atmosphere to produce a thin TiOx interfacial layer, protects the TI surface, without significantly compromising spin transport from the magnetic material across the TiOx to the TI surface states. First, it is demonstrated that in Bi2Te3/TiOx/Ni80Fe20 heterostructures, TiOx provides an excellent barrier against diffusion of magnetic species, yet maintains a large spin‐pumping effect. Second, the TiOx is also used as a protective capping layer on Bi2Te3, followed by the spin‐spray growth of the MI, NixZnyFe2O4 (NZFO). For the thinnest TiOx barriers, Bi2Te3/TiOx/NZFO samples have antiferromagnetic (AFM) disordered interfacial layer because of diffusion. With increasing TiOx barrier thickness, the diffusion is reduced, but still maintains strong interfacial magnetic exchange‐interaction. These experimental results demonstrate a novel method of low‐temperature growth of magnetic insulators on TIs enabled by interface engineering.

The Conometric Concept: Definitive Rehabilitation of a Single Posterior Implant Using a Friction Retention Abutment. A 1-year Follow-up Report

To provide a 1-year assessment of friction-retention abutments (Acuris, Dentsply Sirona) used to retain a single lithium disilicate (LS2) monolithic restoration. A total of 522 implants were placed to treat single-tooth premolar and molar edentulous sites in the mandible or maxilla. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LS2 monolithic restoration was cemented to a dedicated titanium cap and engaged to the abutment without the use of screws or cement. Any complications affecting the restoration or the opposing dentition, soft tissue dimensional changes, the distance between the implant platform and the bone peak, and pocket probing depths were recorded at the time of restoration placement (T0), after 6 months of function (T1), and after 1 year of function (T2). Esthetic, functional, and biologic parameters were recorded at T0 and T2. A total of 507 patients (284 women and 223 men) received a restoration (T0), and 504 of them reached the T2 1-year follow-up. One restoration fractured after 10 months in function. No statistically significant difference was assessed in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period. The friction retention abutment is a viable option to retain an implant-supported monolithic LS2 glass-ceramic restoration in cases of premolar or molar single-tooth edentulism.

Evaluation of the effects of locally applied rosuvastatin on bone formation in a three-dimensional reconstruction rabbit xenograft model

Guided bone regeneration (GBR) is commonly performed to repair bone defects, and rigid occlusive titanium barriers play a vital role in bone formation in regions with no prior bone tissue. The statin, rosuvastatin (RSV), strongly affects bone apposition when applied locally. Here, we aimed to evaluate the anabolic effects of locally applied RSV with a xenograft placed on rabbit calvaria. Two rigid occlusive titanium caps were used in 16 rabbits after decorticating the calvarial bone. In the control group, the area under the cap was filled with a xenograft, while in the RSV group, a xenograft in combination with RSV (1 mg) was used. In both groups, at 6 and 12 weeks, new bone, residual graft, soft tissue areas, and histological and radiological bone volume were evaluated. At 12 weeks, histologically, the RSV group exhibited superior new bone proportion values, and radiologically, new bone and total bone volume in the RSV group were significantly higher than in the control group (p < 0.05); there were no significant differences at 6 weeks (p > 0.05). According to our results, RSV applied locally under a titanium barrier on an area to be repaired with bone grafts increases new bone and total bone volume.

Ti Interlayer Mediated Uniform NiGe Formation under Low-Temperature Microwave Annealing

The reactions between nickel and germanium are investigated by the incorporation of a titanium interlayer on germanium (100) substrate. Under microwave annealing (MWA), the nickel germanide layers are formed from 150 °C to 350 °C for 360 s in ambient nitrogen atmosphere. It is found that the best quality nickel germanide is achieved by microwave annealing at 350 °C. The titanium interlayer becomes a titanium cap layer after annealing. Increasing the diffusion of Ni by MWA and decreasing the diffusion of Ni by Ti are ascribed to induce the uniform formation of nickel germanide layer at low MWA temperature.

Minocycline Hydrochloride as a Potential Adjuvant to Improve Osteoconductive and Osteoinductive Properties of Bone Substitutes in an Extra-Skeletal Bone Augmentation Model: Preliminary Observations in Rats

Abstract Objectives The present study was performed to determine if minocycline HCl could influence the behavior of deproteinized bovine bone mineral (DBBM) and bioactive glass (BG) particles when used as filler material for new bone generation in a guided bone augmentation model. Materials and Methods Two occlusive titanium caps were placed on the rat calvaria. One filled with BG particles, the second with DBBM particles, both previously mixed with blood (control). In minocycline HCl loaded groups (experimental), grafts were additionally placed into a minocycline solution. Samples were harvested after 4, 8, and 16 weeks. Half of the samples were embedded in methylmethacrylate for undecalcified histology and the other half was fixed, decalcified, and embedded in paraffin for classical histologic analysis. Results The control groups highlighted osteoconductive and osteoinductive responses associated to BG particles, as well as an osteoconductive reaction, in DBBM sections. The addition of minocycline HCl to BG particles had no measurable influence on the result. In minocycline HCl loaded DBBM sections; however, areas of spontaneous ossification could be observed after 8 and 16 weeks. Conclusion Our observations suggest that minocycline HCl may add some osteoinductive properties to DBBM within the limitations of this study design. Further investigations are needed to refine the present results.

Effect of rhBMP-2 applied with a 3D-printed titanium implant on new bone formation in rabbit calvarium.

Objective This study sought to compare the biocompatibility of a three-dimensional (3D)-printed titanium implant with a conventional machined titanium product, as well as the effect of such implant applied with recombinant human Bone Morphogenetic Protein Type 2 (rhBMP-2) for guided bone regeneration.Methodology Disk-shaped titanium specimens fabricated either by the conventional machining technique or by the 3D-printing technique were compared by MC3T3-E1 cells cytotoxicity assay. New bone formation was evaluated using a rapid prototype titanium cap applied to the calvaria of 10 rabbits, which were divided into two groups: one including an atelopeptide collagen plug on one side of the cap (group I) and the other including a plug with rhBMP-2 on the other side (group II). At six and 12 weeks after euthanasia, rabbits calvaria underwent morphometric analysis through radiological and histological examination.Results Through the cytotoxicity assay, we identified a significantly higher number of MC3T3-E1 cells in the 3D-printed specimen when compared to the machined specimen after 48 hours of culture. Moreover, morphometric analysis indicated significantly greater bone formation at week 12 on the side where rhBMP-2 was applied when evaluating the upper portion immediately below the cap.Conclusion The results suggest that 3D-printed titanium implant applied with rhBMP-2 enables new bone formation.

Microanalysis of silicon protrusions with a titanium cap formed via surface melting and solidification under applied tensile stress

Silicon (Si) protrusions with a peculiar-shaped cap at their top were microanalyzed using scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) and scanning Auger electron spectroscopy/microscopy. The Si protrusions were formed on a Si(111) substrate via the process of surface melting by DC resistive heating above 1000 °C and solidification under applied tensile stress. The protrusions were micro-sampled by the techniques with focused ion beam, and their cross-sectioned planes were examined by SEM with EBSD. The analysis revealed that the Si protrusions were epitaxially grown as a single crystal on the Si(111) substrate and deposition of titanium (Ti) resulted in formation of the cap as Ti precipitation with other minor impurities. The formation mechanism of the Si protrusion was discussed in terms of surface melting flow in the non-uniform temperature distribution under stress via electromigration, diffusion suppression due to stress-induced steps, and solidification including freezing point depression of the melted Si with the impurities.

Ultra-broadband absorber from visible to near-infrared using plasmonic metamaterial.

We propose a design of an ultra-broadband absorber based on a thin metamaterial nanostructure composed of a periodic array of titanium-silica (Ti-SiO2) cubes and an aluminum (Al) bottom film. The proposed structure can achieve nearly perfect absorption with an average absorbance of 97% spanning a broad range from visible to near-infrared (i.e., from 354 nm to 1066 nm), showing a 90% absorption bandwidth over 712 nm, and the peak absorption is up to 99.8%. The excitation of superior surface plasmon resonance combined with the resonance induced by the metal-insulator-metal Fabry-Perot (FP) cavity leads to this broadband perfect absorption. The polarization and angle insensitivity is demonstrated by analyzing the absorption performance with oblique incidences for both TE- and TM-polarized waves. In addition, we discuss the impact of various metal materials and geometry structure on absorption performance in detail. The proposed broadband metamaterial absorber shows a promising prospect in applications such as solar cell, infrared detection, and imaging. Moreover, the use of a thin titanium cap and an aluminum film instead of noble metals has the potential to reduce production cost in applications.

In situ high-temperature X-ray diffraction analysis of Mg2Si formation kinetics via reaction of Mg films with Si single crystal substrates

Conformal compact Mg2Si films can be formed on Si substrates (for battery, photovoltaic, thermoelectric, or other applications) via the direct reaction of Mg films with such substrates at modest temperatures (≥280 °C). In this work, in situ high-temperature X-ray diffraction (HTXRD) analyses have been used to track the reactive conversion of Mg films on Si single crystal (wafer) substrates into Mg2Si at 280–400 °C in a flowing He atmosphere. Prior reported complications associated with the evaporation or oxidation of magnesium films during heating were avoided by applying a thin (15 nm) titanium capping layer on the 1 μm thick magnesium films. The reaction of Mg films with <100> oriented and <111> oriented Si single crystals proceeded at parabolic rates with time. Similar values were obtained for the parabolic rate constants and activation energies for Mg reaction with both Si substrate orientations. These observations were consistent with solid-state diffusion through the thickening Mg2Si product as the rate-limiting step. The activation energy values obtained for Mg2Si formation were consistent with a previously reported correlation between the activation energies and melting points of other M2Si-type silicides formed by solid-state-diffusion-limited reaction with Si substrates.

S-nitroso albumin enhances bone formation in a rabbit calvaria model

Nitric oxide (NO) is a mediator involved in bone regeneration. We therefore examined the effect of the novel NO donor, S-nitroso human serum albumin (S-NO-HSA) on bone formation in a rabbit calvaria augmentation model.Circular grooves (8mm diameter, two per animal) were created by a trephine drill in the cortical bone of 40 rabbits and titanium caps were placed on the rabbit calvaria bone filled with a collagen sponge soaked with either 100μL S-NO-HSA (5%, 20%) or human albumin (5%, 20%). After 4 weeks the titanium hemispheres were subjected to histological and histomorphometric analysis. Bone formation and the volume of the residual collagen sponge were evaluated.S-NO-HSA treatment groups had a significantly higher volume of newly formed bone underneath the titanium hemispheres compared to the albumin control groups (5%: 15.5±4.0% versus 10.6±2.9%; P<0.05; 20%: 14.0±4.6% versus 6.0±3.8%; P<0.01). The volume of residual collagen sponge was also significantly lower in the S-NO-HSA groups compared to the control groups (5%: 0.4±0.5% versus 2.6±2.4%; P<0.05 and 20%: 1.5±2.7% versus 13.0±18.7%; P<0.01).This study demonstrates for the first time that S-NO-HSA promotes bone formation by slow NO release. Additionally, S-NO-HSA increases collagen sponge degradation.

가토의 두개골에서 Pore의 유무에 따른 티타늄 반구에서의 골형성 능

Purpose: This study is performed to determine the effects of titanium cap with various sizes of pores on bone formation during guided bone regeneration (GBR). Methods: Calvaria from 10 adult male rabbits were chosen as the recipient sites. A trephine bur with a diameter of 10 mm was used to form one round groove on each side of sagittal suture of the cranium, and a round bur with a diameter of 1.5 mm was used to form 6 small holes on the inner circles of round grooves to induce bleeding. In the control group, bone graft was not conducted, and closed titanium cap was fixed in the round groove. Bone graft was not performed in groups 1 and 2, but fixed on titanium caps with 0.2 mm, and 0.5 mm sized pores, respectively. For groups 3, 4, and 5, a synthetic bone graft material (β-tricalcium phosphate, Cerasorb Ⓡ , Germany) was transplanted, and titanium caps without pore, with 0.2 mm and 0.5 mm sized pore were fixed, respectively. The animals were sacrificed 4 weeks after, and clinical, radiographical, and histomorphometrical evaluation of bone regeneration was performed. Results: In all groups, there were no clinical signs of infection, inflammation or wound dehiscence. Radiographic evaluation revealed well-defined semi-circular radiopacity inside the titanium cap of groups 3, 4, and 5. Histologically, the inner surface of the hemisphere was evenly lined with newly formed bone tissue, as well as grafted bone material in the group 3. In groups 4 and 5, the insertion of connective tissue was observed along the inner surface. However, the overall surface area between the grafts with different holes yielded no statistical significance in the histomorphometrical evaluation. Conclusion: Although the total area of newly formed bone showed no significant difference, excellent bone formation tendency was observed histologically when closed caps were used with bone graft was accompanied.

Bone Augmentation in a Titanium Cap with a Porous Surface Modified by Microarc Oxidation

To compare bone augmentation on pure titanium-machined surfaces and surfaces that have been modified by microarc oxidation (MAO) using titanium caps. Twenty caps were manufactured from rods of commercially pure titanium. The control group (CG) consisted of 10 titanium caps with machined inner walls. The test group (TG) consisted of 10 titanium caps that were modified by MAO in an electrolyte solution containing calcium phosphate ions. The two types of titanium caps were fixed on the calvaria of 10 New Zealand rabbits. Each rabbit received two different caps. Although each cap was unfilled, the marrow and blood from the wound of the rabbit skulls could penetrate into the caps. After 4 weeks, the rabbits were sacrificed, and the skulls were removed for observation. The zenith of new bone was measured directly after the caps were removed from the skulls; subsequently, the bone volume was calculated by microcomputed tomography. Little bone augmentation could be observed in the CG caps, and the new bone height of the CG group was inconspicuous. In contrast, the new bone extended along the inner walls of the TG caps. The mean height of new bone of the TG group was 2.3 ± 0.28 mm. The mean volume of new bone in the TG group was 18.63 ± 3.80 mm(3). New bone formation in a titanium cap surface modified by MAO was greater than that of a nonmodified cap. A titanium cap allowed new bone formation on the MAO surface to be observed and is a promising device for bone augmentation. Additionally, this finding suggests that observation through a titanium cap is a feasible method for biomaterial testing in hard tissue.

Histological and immunohistochemical evaluation of the peri-implant soft tissues around machined and acid-etched titanium healing abutments: a prospective randomised study

A close spatial correlation has been described between the roughness of intraoral materials and the rate of bacterial colonisation. The aim of the present study in man was to conduct a comparative immunohistochemical evaluation of the inflammatory infiltrate, microvessel density, the nitric oxide synthases 1 and 3 and the vascular endothelial growth factor expression, the proliferative activity, and the B and T lymphocyte and histiocyte positivity in the peri-implant soft tissues around machined and acid-etched titanium healing caps. Ten patients participated in this study. The patients were enrolled consecutively. All patients received dental implants left to heal in a non-submerged mode. Healing caps were inserted in all implants. Half of the implants were supplied randomly with machined caps of titanium (control), while the other half were provided randomly with acid-etched titanium caps (test). After a 6-month healing period, a gingival biopsy was performed with a circular scalpel around the healing caps of both groups. The inflammatory infiltrate was mostly present in test specimens. Their extension was much larger than that of the control samples. A higher number of T and B lymphocytes were observed in test specimens. Higher values of microvessel density and a higher expression of vascular endothelial growth factor intensity were observed in the test samples. Furthermore, the Ki-67, NOS1 and NOS3 expression was significantly higher in the test specimens. All these results showed that the tissues around test healing caps underwent a higher rate of restorative processes, most probably correlated to the higher inflammation processes observed in these tissues.

Correlation in the densities of augmented and existing bone in guided bone augmentation

Our previous work used a rabbit experimental model to investigate the effectiveness of guided bone augmentation (GBA). Although a density similar to that of existing bone is required for successful bone augmentation, few studies have compared the densities of augmented and existing bone. The purpose of the present study was to investigate the correlation in the densities of existing and augmented bone following GBA in rabbit calvaria. The calvaria of 18 adult male Japanese white rabbits were exposed. A circular groove and nine small holes were drilled into the cortical surface of each left parietal bone. A customized, standardized, hemispherical titanium cap was press-fitted into each groove. Six animals were sacrificed after each healing period of 1, 3, and 6 months and histomorphometric analyses were conducted. Significant increases were observed in the area of augmented bone between 1 and 6 months (62.7 ± 21.6% vs. 93.4 ± 3.9%). In contrast, no significant differences among healing periods were observed in the density of augmented or existing bone. Regression analysis demonstrated a significant positive correlation between the densities of augmented and existing bone; the strength of this correlation increased with the length of healing (R(2) =0.97). These results suggest that the area of augmented bone increases significantly with the length of healing, filling the occlusive space after 6 months, and that the density of augmented bone depends on that of the existing bone, such that augmented bone has a density about half that of the existing bone.

Transmission electron microscopy study of erbium silicide formation from Ti/Er stack for Schottky contact applications

In this paper, we present results of transmission electron microscopy studies on erbium silicide structures fabricated under various thermal conditions. A titanium cap has been used as a protective layer against oxidation during rapid thermal annealing of an erbium layer in a temperature range of 300-700 degrees C. Both layers (200 nm Ti and 25 nm Er) were deposited by electron-beam sputtering. The investigations have shown that the transformation of the 25-nm-thick erbium into erbium silicide is completed after annealing at 500 degrees C. At higher temperatures, the formation of a titanium silicide layer above erbium silicide is observed. The lowest Schottky barrier has been measured in the sample annealed at 700 degrees C.

Effects of α-DT cement with hydroxypropyl cellulose on bone augmentation within a titanium cap in the rabbit calvarium

The present study was performed to evaluate the effects of calcium phosphate cement (alpha-DT cement) containing alpha-TCP, dicalcium phosphate anhydrous, and tetracalcium phosphate mixed with hydroxypropyl cellulose (HPC) for bone augmentation within a titanium cap in the rabbit calvarium. A total of 24 male adult Japanese white rabbits were used in this study. In each rabbit, one side of the cap was filled with alpha-DT cement (alpha-DT) or alpha-DT cement mixed with HPC (alpha-DTH), and the other side of the cap was left empty (control). After 1 and 3 months, newly generated tissue and mineralized bone areas were measured histomorphometrically. Significant differences in newly generated tissue and mineralized tissue were observed between the alpha-DT or alpha-DTH group and the control at 3 months. Furthermore, alpha-DTH showed significantly more mineralized tissue than alpha-DT group. Our findings indicated that although alpha-DT cement was effective for bone augmentation, alpha-DTH was more useful than alpha-DT for bone maturation.

Evaluation of bone formation by recombinant human BMP-2 and rapid prototype titanium cap in rabbit calvaria using micro computed tomography

치과용 임플란트의 대중화와 더불어 치조골의 결손부에 서 골증대를 위한 여러 가지 노력을 하고 있으며, 이와 더 불어 골재생 시 골을 좀 더 효과적이며 빠르고 원하는 모양 으로 형성하기 위한 노력이 이루어지고 있다. 치조골 결손 부에 대한 골증대가 필요한 경우, 골이식을 이용한 골유도 재생술(guided bone regeneration, GBR), 중첩골이식술 (onlay bone graft) 및 상악동저거상술(sinus elelvation with bone graft) 등을 이용하며, 또한 치조골확장술(ridge expansion osteotomy)과 수직치조골신장술(vertical alveolar distraction osteogenesis) 등의 술식을사용하고 있다. 골유도재생술은 골이식 시 골이식 부위로의 상피세포 또 는 결체조직 등이 침투하지 못하도록 차단하여 골형성을 도모하는 방법으로, 다양한 골이식재와 함께 흡수성 및 비 흡수성막을 차폐막으로 흔히 사용하고 있다. Titanium cap도 차폐막으로 골증대술에서 사용할 수 있으며, 골증 대술 시 titanium barrier 차폐막의 효용성에 대한 많은 연구 도 보고되고 있다. 그러나 기존 연구에서 이용한 titanium barrier는 절삭 등에 의한 방법으로 제작되어 실제 임상에 적용할 때 다양한 치조골 결손부의 형태를 반영하여 제작 하기에는 많은 어려움이 있다. 그러나 titanium을 이용하여 cap을 제작할 때 rapid prototype (RP) 기법을 이용하면 원하 오 희 균 500-757 광주광역시북구용봉로 77 전남대학교치의학전문대학원구강악안면외과학교실 Hee-Kyun Oh Department of Oral and Maxillofacial Surgery, School of Dentistry, Chonnam National University 77 Yongbong-ro, Buk-gu, Gwangju, 500-757, Korea TEL: +82-62-530-5618 FAX: +82-62-530-5619 E-mail: hkoh@chonnam.ac.kr RP titanium cap과 rhBMP-2를 이용하여 형성된