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The Journal of Prosthetic Dentistry Jun 2024While the presence of a ferrule has been reported to be essential for post-and-core restorations, many extensively damaged teeth lack complete ferrules. The outcome of...
STATEMENT OF PROBLEM
While the presence of a ferrule has been reported to be essential for post-and-core restorations, many extensively damaged teeth lack complete ferrules. The outcome of post-and-core restorations for these teeth remains uncertain.
PURPOSE
The purpose of this retrospective clinical study was to assess the outcome of cast alloy post-and-cores and knife-edged crowns for the restoration of teeth lacking complete ferrules.
MATERIAL AND METHODS
A total of 106 participants with endodontically treated teeth with 2 or fewer walls with ferrules who had received cast precious metal alloy post-and-cores along with knife-edged crowns between 2013 and 2022 were recalled for a clinical examination. The minimum follow-up time was 5 months after restoration, and restoration failure and the periodontal status difference between restored teeth and reference teeth were determined. Kaplan-Meier analysis was performed to obtain success curves. The influence of age, sex, jaw position, tooth type, and antagonistic dentition upon the success function was analyzed with the log-rank or Breslow test (α=.05).
RESULTS
A total of 100 participants with 130 restorations were studied. The success rate of the restorations was 93.85% in a mean ±standard deviation period of 48.3 ±26.1 months. The estimated 5-year cumulative success probability was 91.61%. No significant effect on the success of restorations was found regarding age, sex, jaw position, tooth type, or antagonistic dentition (P>.05). The main failure types were post debonding, root fracture, and apical periodontitis. No statistical difference in tooth mobility (Z=-1.265, P=.206) was found between the restored and the reference teeth, but the plaque index and calculus index of the restored teeth were significantly lower than of the reference teeth (Z=-7.216, P<.001; Z=-7.044, P<.001). Teeth that had received cast post-and-cores and knife-edged crowns were found to have no significant correlation with periodontal disease (χ²=1.131, P=.288) or bleeding on probing (χ²=3.436, P=.064).
CONCLUSIONS
The clinical outcomes for the restoration of teeth with 2 or fewer walls with ferrules using cast precious metal alloy post-and-cores and knife-edged crowns were favorable, exhibiting a high 5-year cumulative success probability and no increased periodontal health risk.
PubMed: 38942716
DOI: 10.1016/j.prosdent.2024.05.015 -
World Neurosurgery Jun 2024To design and evaluate ceramic aneurysm clips with integrated titanium springs, focusing on ergonomic application and precision in neurosurgical procedures.
OBJECTIVE
To design and evaluate ceramic aneurysm clips with integrated titanium springs, focusing on ergonomic application and precision in neurosurgical procedures.
METHODS
The clip design was executed with precision using Creo Parametric 3D CAD software. It comprises a zirconia body and a titanium spring for durability and consistent tension and features a four-coil hairpin titanium spring for enhanced closing force and a ball-type head for versatile maneuverability during surgery. To assess durability, closing forces were rigorously measured using a force gauge system, comparing the ceramic clip with the standard Mizuho permanent clip over 30 open-close cycles. For MR artifact assessment, both ceramic and Yasargil clips were evaluated using a 3 Tesla magnetic resonance imaging (MRI) scanner with specific imaging sequences.
RESULTS
The straight type ceramic clip's initial closing force was 1.70 N, dropping to 1.22 N after 30 cycles, indicating a retention of 72% of its initial force. In MRI, the ceramic clip displayed significantly lower measurement discrepancies compared to the titanium alloy Yasargil clip, particularly in high resolution T1 weighted images. The lowest variance was at measurement point L2, where the ceramic clip showed 3% discrepancy. Further, the ceramic clip yielded clearer images than the titanium alloy clip, particularly at the clip's end.
CONCLUSIONS
Ceramic clips with titanium springs demonstrated satisfactory closing force and superior MRI compatibility, promising enhancements in surgical application and postoperative assessment.
PubMed: 38942145
DOI: 10.1016/j.wneu.2024.06.105 -
Journal of Colloid and Interface Science Jun 2024Electrochemical nitrate reduction reaction (NORR) offers a cost-effective and environmentally friendly method to simultaneously yield valuable NHand alleviate...
Electrochemical nitrate reduction reaction (NORR) offers a cost-effective and environmentally friendly method to simultaneously yield valuable NHand alleviate NOpollution under mild operating conditions.However, this complicated eight-electron reaction suffers from low selectivity and Faradaic efficiency, which highlight the importance of developing efficient catalysts, but still a critical challenge. Here, a theoretical screening is performed on transition metal-tetragonal carbon nitride (TM@T-CN) as active and selective electrocatalysts for NORR, where detailed reaction mechanisms and activity origins are explored. In addition, five-step screening criteria and volcano plots enable fast prescreening among numerous candidates.We identify that V@T-CN and Cr@T-CN are promising candidates with low overpotentials and high selectivity and stability. In particular, a significant negative correlation between the adsorption strength ofnitrate and the Gibbs free energy for the last proton-electron coupling step (*NH→*NH) was existed, which is considerably advantaged to track the activity trend and reveal the origin of activity. This work provides theoretical insights into the rational design of TM-N/C catalysts for NORR andpaves a valuable electrochemical screening framework for other multi-step reactions.
PubMed: 38941929
DOI: 10.1016/j.jcis.2024.06.178 -
Biomaterials Advances Jun 2024Additive manufacturing (AM) of Ti-based biomedical implants is a pivotal research topic because of its ability to produce implants with complicated geometries. Despite...
A novel titanium alloy for load-bearing biomedical implants: Evaluating the antibacterial and biocompatibility of Ti536 produced via electron beam powder bed fusion additive manufacturing process.
Additive manufacturing (AM) of Ti-based biomedical implants is a pivotal research topic because of its ability to produce implants with complicated geometries. Despite desirable mechanical properties and biocompatibility of Ti alloys, one major drawback is their lack of inherent antibacterial properties, increasing the risk of postoperative infections. Hence, this research focuses on the Ti536 (Ti5Al3V6Cu) alloy, developed through Electron Beam Powder Bed Fusion (EB-PBF), exploring bio-corrosion, antibacterial features, and cell biocompatibility. The microstructural characterization revealed grain refinement and the formation of TiCu precipitates with different morphologies and sizes in the Ti matrix. Electrochemical tests showed that Cu content minimally influenced the corrosion current density, while it slightly affected the stability, defect density, and chemical composition of the passive film. According to the findings, the Ti536 alloy demonstrated enhanced antibacterial properties without compromising its cell biocompatibility and corrosion behavior, thanks to TiCu precipitates. This can be attributed to both the release of Cu ions and the TiCu precipitates. The current study suggests that the EB-PBF fabricated Ti536 sample is well-suited for use in load-bearing applications within the medical industry. This research also offers an alloy design roadmap for novel biomedical Ti-based alloys with superior biological performance using AM methods.
PubMed: 38941776
DOI: 10.1016/j.bioadv.2024.213928 -
Mikrochimica Acta Jun 2024A novel nitrogen-doped ordered mesoporous carbon (OMC) pore-embedded growth Pt-Ru-Fe nanoparticles (Pt-Ru-Fe@N-OMCs) composite was designed and synthesized for the first...
A novel nitrogen-doped ordered mesoporous carbon (OMC) pore-embedded growth Pt-Ru-Fe nanoparticles (Pt-Ru-Fe@N-OMCs) composite was designed and synthesized for the first time. SBA-15 was used as a template, and dopamine was used as a carbon and nitrogen source and metal linking reagent. The oxidative self-polymerization reaction of dopamine was utilized to polymerize dopamine into two-dimensional ordered SBA-15 template pores. Iron porphyrin was introduced as an iron source at the same time as polymerization of dopamine, which was introduced inside and outside the pores using dopamine-metal linkage. Carbonization of polydopamine, nitrogen doping and iron nanoparticle formation were achieved by one-step calcination. Then the templates were etched to form Fe@N-OMCs, and finally the Pt-Ru-Fe@N-OMCs composites were stabilized by the successful introduction of platinum-ruthenium nanoparticles through the substitution reaction. The composite uniformly embeds the transition metal nanoparticles inside the OMC pores with high specific surface area, which limits the size of the metal nanoparticles inside the pores. At the same time, the metal nanoparticles are also loaded onto the surface of the OMCs, realizing the uniform loading of metal nanoparticles both inside and outside the pores. This enhances the active sites of the composite, promotes the mass transfer process inside and outside the pores, and greatly enhances the electrocatalytic performance of the catalyst. The material shows high electrocatalytic performance for adrenaline, which is characterized by a wide linear range, high sensitivity and low detection limit, and can realize the detection of actual samples.
PubMed: 38940957
DOI: 10.1007/s00604-024-06498-8 -
The Review of Scientific Instruments Jun 2024The performance of next-generation particle accelerators has been adversely affected by the occurrence of electron multipacting and vacuum instabilities. Particularly,...
The performance of next-generation particle accelerators has been adversely affected by the occurrence of electron multipacting and vacuum instabilities. Particularly, minimization of secondary electron emission (SEE) and reduction of surface resistance are two critical issues to prevent some of the phenomena such as beam instability, reduction of beam lifetime, and residual gas ionization, all of which occur as a result of these adverse effects in next-generation particle accelerators. For the first time, novel quinary alloy Ti-Zr-V-Hf-Cu non-evaporable getter (NEG) films were prepared on stainless steel substrates by using the direct current magnetron sputtering technique to reduce surface resistance and SEE yield with an efficient pumping performance. Based on the experimental findings, the surface resistance of the quinary Ti-Zr-V-Hf-Cu NEG films was established to be 6.6 × 10-7 Ω m for sample no. 1, 6.4 × 10-7 Ω m for sample no. 2, and 6.2 × 10-7 Ω m for sample no. 3. The δmax measurements recorded for Ti-Zr-V-Hf-Cu NEG films are 1.33 for sample no. 1, 1.34 for sample no. 2, and 1.35 for sample no. 3. Upon heating the Ti-Zr-V-Hf-Cu NEG film to 150 °C, the XPS spectra results indicated that there are significant changes in the chemical states of its constituent metals, Ti, Zr, V, Hf, and Cu, and these chemical state changes continued with heating at 180 °C. This implies that upon heating at 150 °C, the Ti-Zr-V-Hf-Cu NEG film becomes activated, showing that novel quinary NEG films can be effectively employed as getter pumps for generating ultra-high vacuum conditions.
PubMed: 38940644
DOI: 10.1063/5.0198398 -
Machine Learning Force Field-Aided Cluster Expansion Approach to Phase Diagram of Alloyed Materials.Journal of Chemical Theory and... Jun 2024First-principles approaches based on density functional theory (DFT) have played important roles in the theoretical study of multicomponent alloyed materials....
First-principles approaches based on density functional theory (DFT) have played important roles in the theoretical study of multicomponent alloyed materials. Considering the highly demanding computational cost of direct DFT-based sampling of the configurational space, it is crucial to build efficient and low-cost surrogate Hamiltonian models with DFT accuracy for efficient simulation of alloyed systems with configurational disorder. Recently, the machine learning force field (MLFF) method has been proposed to tackle complicated multicomponent disordered systems. However, the importance of integrating significant physical considerations, including, in particular, convex hull preservation, which is the prerequisite for the accurate prediction of phase diagrams, into the training process of the MLFF remains rarely addressed. In this work, a workflow is proposed to train a convex-hull-preserved (CHP) MLFF for binary alloy systems, based on which the order-disorder phase boundary is predicted by using the Wang-Landau Monte Carlo (WLMC) technique. The predicted values for order-disorder phase transition temperatures agree well with the experiment. The CHP-MLFF is further used to build CE models with the same accuracy as the MLFF and higher efficiency in sampling configurational space. Using the results obtained from the MLFF-based WLMC simulation as a reference, the performances of different schemes for constructing CE models were evaluated in a transparent manner, which revealed the close correlation between the prediction accuracy of ground-state configurations and that of the order-disorder phase transition temperature. This work clearly indicates the great importance of reproducing the convex hull and energetics of ground-state configurations when constructing surrogate Hamiltonians for the statistical modeling of alloyed systems.
PubMed: 38940547
DOI: 10.1021/acs.jctc.4c00463 -
Exploration (Beijing, China) Jun 2024The coupling electrosynthesis involving CO upgrade conversion is of great significance for the sustainable development of the environment and energy but is challenging....
The coupling electrosynthesis involving CO upgrade conversion is of great significance for the sustainable development of the environment and energy but is challenging. Herein, we exquisitely constructed the self-supported bimetallic array superstructures from the Cu(OH) array architecture precursor, which can enable high-performance coupling electrosynthesis of formate and adipate at the anode and the cathode, respectively. Concretely, the faradaic efficiencies (FEs) of CO-to-formate and cyclohexanone-to-adipate conversion simultaneously exceed 90% at both electrodes with excellent stabilities. Such high-performance coupling electrosynthesis is highly correlated with the porous nanosheet array superstructure of CuBi alloy as the cathode and the nanosheet-on-nanowire array superstructure of CuNi hydroxide as the anode. Moreover, compared to the conventional electrolysis process, the cell voltage is substantially reduced while maintaining the electrocatalytic performance for coupling electrosynthesis in the two-electrode electrolyzer with the maximal FE and FE up to 94.2% and 93.1%, respectively. The experimental results further demonstrate that the bimetal composition modulates the local electronic structures, promoting the reactions toward the target products. Prospectively, our work proposes an instructive strategy for constructing adaptive self-supported superstructures to achieve efficient coupling electrosynthesis.
PubMed: 38939862
DOI: 10.1002/EXP.20230043 -
Exploration (Beijing, China) Jun 2024To overcome the overheating phenomena of electronic devices and energy components, developing advanced energy-free cooling coatings with promising radiative property...
To overcome the overheating phenomena of electronic devices and energy components, developing advanced energy-free cooling coatings with promising radiative property seem an effective and energy-saving way. However, the further application of these coatings is greatly limited by their sustainability because of their fragile and easy contamination. Herein, it is reported that a bioinspired radiative cooling coating (BRCC) displayed sustainably efficient heat dissipation by the combination of high emittance and robust self-cleaning property. With the hierarchical porous structure constructed by multiwalled carbon nanotubes (MWCNTs), modified SiO and fluorosilicone (FSi) resin, the involvement of the BRCC improves the cooling performance by increasing ≈25% total heat transfer coefficient. During the abrasion and soiling tests, the BRCC-coated Al alloy heat sink always displays stable radiative cooling performance. Moreover, the simulation and experimental results both revealed that reducing surface coverage of BRCC (≈80.9%) can still keep highly cooling efficiency, leading to a cost-effective avenue. Therefore, this study may guide the design and fabrication of advanced radiative cooling coating.
PubMed: 38939859
DOI: 10.1002/EXP.20230085 -
Scientific Reports Jun 2024Metallic structures produced with laser powder bed fusion (LPBF) additive manufacturing method (AM) frequently contain microscopic porosity defects, with typical...
Metallic structures produced with laser powder bed fusion (LPBF) additive manufacturing method (AM) frequently contain microscopic porosity defects, with typical approximate size distribution from one to 100 microns. Presence of such defects could lead to premature failure of the structure. In principle, structural integrity assessment of LPBF metals can be accomplished with nondestructive evaluation (NDE). Pulsed infrared thermography (PIT) is a non-contact, one-sided NDE method that allows for imaging of internal defects in arbitrary size and shape metallic structures using heat transfer. PIT imaging is performed using compact instrumentation consisting of a flash lamp for deposition of a heat pulse, and a fast frame infrared (IR) camera for measuring surface temperature transients. However, limitations of imaging resolution with PIT include blurring due to heat diffusion, sensitivity limit of the IR camera. We demonstrate enhancement of PIT imaging capability with unsupervised learning (UL), which enables PIT microscopy of subsurface defects in high strength corrosion resistant stainless steel 316 alloy. PIT images were processed with UL spatial-temporal separation-based clustering segmentation (STSCS) algorithm, refined by morphology image processing methods to enhance visibility of defects. The STSCS algorithm starts with wavelet decomposition to spatially de-noise thermograms, followed by UL principal component analysis (PCA), fine-tuning optimization, and neural learning-based independent component analysis (ICA) algorithms to temporally compress de-noised thermograms. The compressed thermograms were further processed with UL-based graph thresholding K-means clustering algorithm for defects segmentation. The STSCS algorithm also includes online learning feature for efficient re-training of the model with new data. For this study, metallic specimens with calibrated microscopic flat bottom hole defects, with diameters in the range from 203 to 76 µm, were produced using electro discharge machining (EDM) drilling. While the raw thermograms do not show any material defects, using STSCS algorithm to process PIT images reveals defects as small as 101 µm in diameter. To the best of our knowledge, this is the smallest reported size of a sub-surface defect in a metal imaged with PIT, which demonstrates the PIT capability of detecting defects in the size range relevant to quality control requirements of LPBF-printed high-strength metals.
PubMed: 38937533
DOI: 10.1038/s41598-024-64214-1