Metal-ceramic bond strength of a cobalt chromium alloy for dental prosthetic restorations with a porous structure using metal 3D printing

Wang, Hongfei,Lim, Joong Yeon Elsevier 2019 Computers in biology and medicine Vol.112 No.-

<P><B>Abstract</B></P> <P>Selective laser sintering (SLS) is a new type of additive material manufacturing technology. The development of precise 3D metal printing technology has enabled the printing of complicated metal structures, particularly in the medical field. Finding a way to integrate new technologies with Co–Cr alloys for the precision manufacturing of dental restoration materials and a way to improve the metal-ceramic bonding strength of the materials have become a key focus of dental restoration clinical trials. The purpose of this study is to evaluate bonding strength and ceramic adhesion between metal and ceramics using Co–Cr specimens with different porous structures manufactured using SLS technology. According to the international standard ISO9693:1999, we printed three sets of 10 rectangular Co–Cr alloy test specimens of the same size (25 × 3 × 0.5 mm) using an SLS-3D metal printer and fused a ceramic layer (8 x 3 × 1.1 mm) to the center of the Co-Cy alloy test specimen. Before testing, we conducted stress and fracture simulation analysis on three specimen types (no holes, circular-shaped holes, and rhombic-shaped holes), using ABAQUS results to predict the results of three-point bending tests. These simulation results were then compared with the experimental data. We used three-point bending tests to assess the bonding strength of the fabricated metal-ceramic bonding surface. We also used a digital microscope (100× and 200×) to observe the surface conditions of the samples. Finally, we analyzed the results using one-way analysis of variance. The ABAQUS bending simulations indicated that the bending energy decreased sequentially for the hole-free, circular-hole and rhombic-hole specimens. Similarly, when the three types of test specimen were manufactured using SLS, significant differences in bending energy were observed between the rhombic-hole specimens and both the hole-free (P < 0.05) and circular-hole specimens (P < 0.05). In addition, the bond strength for all groups was higher than the international minimum standard of 25 MPa (33.36 ± 3.17 MPa). In this research, the bond strength of all three metal-ceramic test specimens was higher than the international minimum standard of 25 MPa set by ISO1999/9693. However, the circular porous design did not show previous diversity with other porous shape design. In addition, due to limitations in the accuracy of 3D printing using SLS, the structural advantages our proposed specimen design are difficult to verify. Therefore, we plan to develop new structural designs to improve the bonding strength of metal-ceramic structures in future work.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Selective laser sintering (SLS) leads to a new type of Additive Manufacturing (AM) in dental restoration. </LI> <LI> The bond strength of simple shape porous Co–Cr alloy can achieve the ISO standard. </LI> <LI> During the SLS process, balling phenomenon tends to cause porosity and even delamination induced by poor inter-layer bonding. </LI> </UL> </P>

Short-term Haze Exposure Predisposes Healthy Volunteers to Nasal Inflammation

Mu Xian,Kuiji Wang,Hongfei Lou,Yang Wang,Luo Zhang,Chengshuo Wang 대한천식알레르기학회 2019 Allergy, Asthma & Immunology Research Vol.11 No.5

Purpose: This study aimed to investigate the impact of short-term haze exposure on nasal inflammation in healthy volunteers. Methods: Thirty-three healthy university students were assessed for nasal symptoms, nasal patency, upper and lower respiratory tract nitric oxide (NO) as well as inflammatory mediators and neuropeptides in nasal secretions before and after a 5-day haze episode. Peripheral blood mononuclear cells (PBMCs) were stimulated with particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5), and cytokines in the supernatants were examined. Results: Mild nasal symptoms were reported by some participants during the haze episode. Objective measures of nasal patency demonstrated that nasal airway resistance was significantly increased from baseline levels, while nasal cavity volume and minimum cross-sectional area were significantly decreased. Similarly, the levels of nasal and exhaled NO, eotaxin, interleukin (IL)-5, chemokine (C-C motif) ligand 17, IL-8, substance P, nerve growth factor and vasoactive intestinal peptides in nasal secretions were significantly increased from baseline values following the haze episode. In contrast, the levels of interferon-γ, IL-10, transforming growth factor-β and neuropeptide Y were significantly decreased. Incubation with 0.1-10 μg/mL PM2.5 significantly increased release of IL-1β, IL-4, IL-5, IL-8 and IL-10 from PBMCs. Conclusions: Short-term haze exposure may lead to nasal inflammation and hypersensitivity in healthy subjects predominantly by Th2 cytokine-mediated immune responses.

Particulate Matter 2.5 Causes Deficiency in Barrier Integrity in Human Nasal Epithelial Cells

Mu Xian,Siyuan Ma,Kuiji Wang,Hongfei Lou,Yang Wang,Luo Zhang,Chengshuo Wang,Cezmi A. Akdis 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.1

Purpose: The effect of air pollution-related particulate matter (PM) on epithelial barrier function and tight junction (TJ) expression in human nasal mucosa has not been studied to date. This study therefore aimed to assess the direct impact of PM with an aerodynamic diameter less than 2.5 μm (PM2.5) on the barrier function and TJ molecular expression of human nasal epithelial cells. Methods: Air-liquid interface cultures were established with epithelial cells derived from noninflammatory nasal mucosal tissue collected from patients undergoing paranasal sinus surgery. Confluent cultures were exposed to 50 or 100 μg/mL PM2.5 for up to 72 hours, and assessed for 1) epithelial barrier integrity as measured by transepithelial resistance (TER) and permeability of fluorescein isothiocyanate (FITC) 4 kDa; 2) expression of TJs using real-time quantitative polymerase chain reaction and immunofluorescence staining, and 3) proinflammatory cytokines by luminometric bead array or enzyme-linked immunosorbent assay. Results: Compared to control medium, 50 and/or 100 μg/mL PM2.5-treatment 1) significantly decreased TER and increased FITC permeability, which could not be restored by budesonide pretreatment; 2) significantly decreased the expression of claudin-1 messenger RNA, claudin-1, occludin and ZO-1 protein; and 3) significantly increased production of the cytokines interleukin-8, TIMP metallopeptidase inhibitor 1 and thymic stromal lymphopoietin. Conclusions: Exposure to PM2.5 may lead to loss of barrier function in human nasal epithelium through decreased expression of TJ proteins and increased release of proinflammatory cytokines. These results suggest an important mechanism of susceptibility to rhinitis and rhinosinusitis in highly PM2.5-polluted areas.

Chinese Society of Allergy and Chinese Society of Otorhinolaryngology-Head and Neck Surgery Guideline for Chronic Rhinosinusitis

Zheng Liu,Jianjun Chen,Lei Cheng,Huabin Li,Shixi Liu,Hongfei Lou,Jianbo Shi,Ying Sun,Dehui Wang,Chengshuo Wang,Xiangdong Wang,Yongxiang Wei,Weiping Wen,Pingchang Yang,Qintai Yang,Gehua Zhang,Yuan Zhan 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.2

The current document is based on a consensus reached by a panel of experts from the Chinese Society of Allergy and the Chinese Society of Otorhinolaryngology-Head and Neck Surgery, Rhinology Group. Chronic rhinosinusitis (CRS) affects approximately 8% of Chinese adults. The inflammatory and remodeling mechanisms of CRS in the Chinese population differ from those observed in the populations of European descent. Recently, precision medicine has been used to treat inflammation by targeting key biomarkers that are involved in the process. However, there are no CRS guidelines or a consensus available from China that can be shared with the international academia. The guidelines presented in this paper cover the epidemiology, economic burden, genetics and epigenetics, mechanisms, phenotypes and endotypes, diagnosis and differential diagnosis, management, and the current status of CRS in China. These guidelines—with a focus on China—will improve the abilities of clinical and medical staff during the treatment of CRS. Additionally, they will help international agencies in improving the verification of CRS endotypes, mapping of eosinophilic shifts, the identification of suitable biomarkers for endotyping, and predicting responses to therapies. In conclusion, these guidelines will help select therapies, such as pharmacotherapy, surgical approaches and innovative biotherapeutics, which are tailored to each of the individual CRS endotypes.

Thermoelectric Performance of Poly(3-hexylthiophene) Films Doped by Iodine Vapor with Promising High Seebeck Coefficient

Hongfei Zhu,Congcong Liu,Haijun Song,Jingkun Xu,Fangfang Kong,Jianmin Wang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2

Poly(3-hexylthiophene) (P3HT) films doped with iodine vapor have been prepared by casting a P3HT solution on glass substrates and their thermoelectric (TE) performances has been investigated. The maximum Seebeck coefficient and electrical conductivity of iodine-doped P3HT films were 386 μV·K−1 (at room temperature) and 4.7 × 10−1 S·cm−1, which is about five orders of magnitude higher than that of pristine P3HT films. The power factor of these iodine-doped P3HT films was estimated to be 7.0 μW·m−1·K−2 at room temperature, which is a relative high value for organic TE materials. The UV-vis spectra of iodine-doped P3HT films showed a slight red shift of the iodine-doped P3HT compared to those of pristine P3HT films. Atomic force microscopy images indicated the conformational changes in P3HT chains after treatment with iodine vapor. During this treatment, the P3HT chains self-organized into a more ordered structure, this organization improved the charge carrier transport capability and the TE performance of P3HT the films.

Microstructure of Nanostructured Zirconia Coating Deposited by Atmospheric Plasma Spraying

Hongfei Sun,Liyong Ni,Canming Wang,Jixin Bi 한국표면공학회 2008 한국표면공학회 학술발표회 초록집 Vol.2008 No.-

Study for Improvement of Laser Induced Damage of 1064 nm AR Coatings in Nanosecond Pulse

Hongfei Jiao,Xinbing Cheng,Jiangtao Lu,Ganghua Bao,Jinlong Zhang,Bin Ma,Huasong Liu,Zhanshan Wang 한국광학회 2013 Current Optics and Photonics Vol.17 No.1

For the conventionally polished fused silica substrate, an around 100 nm depth redeposition polishing layer was formed on the top of surface. Polishing compounds, densely embedded in the redeposition polishing layer were the dominant factor that limited the laser induced damage threshold (LIDT) of transmission elements in nanosecond laser systems. Chemical etching, super-precise polishing and ion beam etching were employed in different ways to eliminate these absorbers from the substrate. After that,Antireflection (AR) coatings were deposited on these substrates in the same batch and then tested by 1064nm nano-pulse laser. It was found that among these techniques only the ion beam etching method, which can effectively remove the polishing compound and did not induce extra absorbers during the disposal process, can successfully improve the LIDT of AR coatings.

Surface Modification of Cellulose Microcrystalline with Aluminate Coupling Agent and Its Effects on Flame Retardant and Mechanical Properties of Epoxy Resin

Minghang Wang,Quan Wu,Zhengyu Feng,Xiaoyu Gu,Hongfei Li,Jun Sun,Bin Fei,Sheng Zhang 한국섬유공학회 2020 Fibers and polymers Vol.21 No.10

Cellulose microcrystalline (CMC), a linear polysaccharide with glucosidic bond, was successfully extracted frombamboo powder and modified by aluminate coupling agent (ACA) to prepare ACA-CMC. The chemical structure of asdesignedACA-CMC was characterized by scanning electron microscopy and Fourier transform infrared spectra. ACACMC,in association with ammonium polyphosphate (APP), was introduced into epoxy resin (EP) by casting process toobtain flame-resistant composites. The fire performance evaluation indicated that the presence of 10 phr APP and 5 phrACA-CMC in EP achieved the maximal LOI value of 29.0 %, passed the UL-94 V-0 rating, and significantly decreased thepeak heat release rate from 1055 kW·m-2 of neat EP to 294 kW·m-2. The introduction of ACA-CMC could also improve themechanical properties of EP composites due to the strengthening effect of CMC and better interfacial compatibility aftermodification with ACA. Moreover, the relative mechanisms were also proposed.

Properties of Fe-based Cr₃C₂ Coating Produced with High Velocity Arc Spraying Process

Canming Wang,Hongfei Sun,Qiang Song 한국표면공학회 2008 한국표면공학회 학술발표회 초록집 Vol.2008 No.-

Cobalt-Porphyrin Modified Three-Dimensional Graphene Hydrogel Electrode for High Performance Asymmetric Supercapacitors

Yuqing Song,Hongfei Wang,Lifeng Yan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.5

Three-dimensional (3D) graphene-based materials have attracted much attention in the field of supercapacitors for their large surface areas and fast electronic conductivity capability. Faradaic pseudo-capacitance materials inside the architecture can enlarge the electrochemical performance of the electrode. Additionally, metal porphyrins are negative electrode active materials for supercapacitors as they have potential high pseudo-capacitance, conductivity and N-doping. The design and preparation of the 3D cobalt-porphyrin modified graphene hydrogels (3D CoP/GHs) is an interesting topic. Here, we have fabricated the 3D CoP/GH by a two-step method. The composite electrode reaches a specific capacitance of 335 F g -1, twice that of pure GHs. At the same time, resistance of the electrode material decreases and the ion transfer is accelerated due to the addition of cobalt-porphyrin. After 10 000 cycles, the 3D CoP/GH maintains its stable specific capacitance retention of 94.11% indicating its excellent cycle life. The cycle life is much better than that of a hydrogel that has not been doped (81.63%) according to our previous work. Then we fabricated an asymmetrical supercapacitor which uses both the 3D CoP/GH and GH as the two electrodes (3D CoP/GHjjGH), and reaches an outstanding energy density of 30.40 Wh kg -1 at a current density of 1 A g -1 while the power density is 749.5 W kg -1.