3D-printed zirconia orthodontic brackets: Effect of printing method on dimensional accuracy.

OBJECTIVES: This study investigated the effect of additive manufacturing (AM) methods on the slot height dimensions and accuracy of 3D-printed orthodontic brackets. METHODS: A 3D model of a standard Mclaughlin Bennett Trevisi bracket was used as a reference to print the ceramic bracket in a 90° orientation using two representative AM methods: digital light processing (DLP) and material jetting (MJ). The dimensional accuracy and slot heights were determined using a scanning electron microscope and an optical scanner. Also, all specimens were analysed using the Geomagic Control X 3D inspection software. The root mean square (RMS) values were used for trueness and precision assessment. Statistical analyses were performed using an independent sample t-test. RESULTS: Slot height dimensions, trueness RMS, and precision RMS were statistically affected by different AM methods (p < .01). There was a significant difference between the different printing methods, with DLP meeting the tolerance requirements (mean slot height = 0.557 ± 0.018 mm) and MJ being slightly below them (mean slot height = 0.544 ± 0.021 mm). However, MJ significantly outperformed DLP in terms of accuracy. Among the two printing methods, MJ was associated with higher trueness (RMS = 0.025 ± 0.004 mm) and precision (RMS = 0.038 ± 0.005 mm). CONCLUSIONS: Both tested AM methods yielded clinically acceptable outcomes, with the RMS range set to ±100 µm and the slot height tolerance established at 0.549-0.569 mm. The MJ technology achieved the highest accuracy.

Epidemiological and clinical characteristics of discharged patients infected with SARS-CoV-2 on the Qinghai Plateau.

Since the outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, a series of confirmed cases of COVID-19 were found on the Qinghai-Tibet plateau. We aimed to describe the epidemiological, clinical characteristics, and outcomes of all confirmed cases in Qinghai, a province at high altitude. The region had no sustained local transmission. Of all 18 patients with confirmed SARS-CoV-2 infection, 15 patients comprising four transmission clusters were identified. Three patients were infected by direct contact without travel history to Wuhan. Of 18 patients, 10 patients showed bilateral pneumonia and two patients showed no abnormalities. Three patients with comorbidities such as hypertension, liver diseases, or diabetes developed severe illness. High C-reactive protein levels and elevations of both alanine aminotransferase and aspartate aminotransferase were observed in three severely ill patients on admission. All 18 patients were eventually discharged, including the three severe patients who recovered after treatment with noninvasive mechanical ventilation, convalescent plasma, and other therapies. Our findings confirmed human-to-human transmission of SARS-CoV-2 in clusters. Patients with comorbidities are more likely to develop severe illness.

TiO2 nanoparticles: low-temperature hydrothermal synthesis in ionic liquids/water and the photocatalytic degradation for o-nitrophenol.

The well-crystallized anatase TiO2-IL nanoparticles were synthesized by one-step routes under low-temperature using room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate as an additional solvent with water. The photocatalytic properties of TiO2 nanoparticles were evaluated by photocatalytic degradation experiments of o-nitrophenol. The TiO2 nanoparticles show a higher photocatalytic activity than the TiO2 with pure water and commercial TiO2 (P25), which may be related to the high crystallinity. The TiO2-IL nanoparticles still hold a high photocatalytic activity after the catalyst was recycled nine times. Chemical oxygen demand removal was achieved under optimum experimental conditions.

Surface characteristics, cytotoxicity, and microbial adhesion of 3D-printed hybrid resin-ceramic materials for definitive restoration.

OBJECTIVE: This study investigated the surface properties, cytotoxicity, and microbial adhesion of 3D-printed specimens made from hybrid resin-ceramic materials intended for use in definitive crowns. METHODS: Disc-shaped specimens were 3D-printed using six different hybrid resin-ceramic materials recommended for definitive restorations: Crowntec (CT), VarseoSmile Crown Plus (VS), Tera Harz TC-80DP Graphy (TH), C&B Permanent ODS (CB), Formlabs Permanent Crown (FP), and HeyGears (HG). Surface topography, surface roughness, and water contact angle values were measured for each material (n = 6). Cytotoxicity was assessed using direct contact and extract tests on human gingival fibroblasts (n = 4). Additionally, the adhesion of mixed oral bacteria to the surfaces of the specimens was evaluated by counting colony-forming units (CFUs) after a 2-hour incubation period (n=6). RESULTS: The TH group exhibited significantly lower surface roughness (Ra: 0.28 ± 0.13 µm) compared to the other materials (CT: 1.87 ± 0.34 µm; VS: 1.13 ± 0.09 µm; CB: 2.91 ± 0.27 µm; FP: 2.50 ± 0.08 µm; HG: 1.50 ± 0.55 µm). The VS group had the highest water contact angle (129.5 ± 1.1°), indicating greater hydrophobicity, in contrast to the other groups (CT: 72.6 ± 2.1°; TH: 75.0 ± 0.3°; CB: 69.1 ± 0.2°; FP: 93.0 ± 1.6°; HG: 77.7 ± 0.3°). Cytotoxicity testing showed no harmful effects, as relative cell viability exceeded 70%, and lactate dehydrogenase (LDH) release remained below 30% for all materials. The TH specimens also demonstrated the lowest bacterial adhesion. CONCLUSIONS: The surface characteristics of the tested resin-ceramic materials varied significantly, with TH showing the smoothest surface and the least bacterial adhesion. All materials were found to be non-toxic. Therefore, TH material has the potential to provide definitive restorations with less microbial adhesion. CLINICAL SIGNIFICANCE: The type of resin-ceramic material significantly affects the surface properties of 3D-printed specimens. These findings are crucial for selecting the appropriate resin-ceramic material for definitive restorations.

Post-processing of a 3D-printed denture base polymer: Impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity.

OBJECTIVES: To investigate the impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity of an additively manufactured denture base polymer. METHODS: The tested specimens were prepared by digital light processing (DLP). A centrifugation method (CENT) was used to remove the residual uncured resin. In addition, the specimens were post-processed with different post-rinsing solutions: isopropanol (IPA), ethanol (EtOH), and tripropylene glycol monomethyl ether (TPM), respectively. A commercial heat-polymerized polymethyl methacrylate was used as a reference (REF). First, the values of surface topography, arithmetical mean height (Sa), and root mean square height (Sq) were measured. Next, flexural strength (FS) and modulus were evaluated. Finally, cytotoxicity was assessed using an extract test. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's multiple comparison test for post-hoc analysis. RESULTS: The Sa value in the CENT group was lower than in the IPA, EtOH, TPM, and REF groups (p < 0.001). Moreover, the CENT group had lower Sq values than other groups (p < 0.001). The centrifugation method showed a higher FS value (80.92 ± 8.65 MPa) than the EtOH (61.71 ± 12.25 MPa, p < 0.001) and TPM (67.01 ± 9.751 MPa, p = 0.027), while affecting IPA (72.26 ± 8.80 MPa, p = 0.268) and REF (71.39 ± 10.44 MPa, p = 0.231). Also, the centrifugation method showed no evident cytotoxic effects. CONCLUSIONS: The surfaces treated with a centrifugation method were relatively smooth. Simultaneously, the flexural strength of denture base polymers was enhanced through centrifugation. Finally, no evident cytotoxic effects could be observed from different post-processing procedures. CLINICAL SIGNIFICANCE: The centrifugation method could optimize surface quality and flexural strength of DLP-printed denture base polymers without compromising cytocompatibility, offering an alternative to conventional rinsing post-processing.

Effect of post-curing conditions on surface characteristics, physico-mechanical properties, and cytotoxicity of a 3D-printed denture base polymer.

OBJECTIVE: This study aims to investigate the influence of post-polymerization (post-curing) conditions on surface characteristics, flexural properties, water sorption and solubility, and cytotoxicity of additively manufactured denture base materials. METHODS: The tested specimens were additively manufactured using digital light processing and classified into different post-curing condition groups: submerged in water (WAT), submerged in glycerin (GLY), and air exposure (AIR). An uncured specimen (UNC) was used as a control. The surface topography and roughness were observed. The flexural strength and modulus were determined via a three-point bending test. The water sorption and solubility were subsequently tested. Finally, an extract test was performed to assess cytotoxicity. RESULTS: Different post-curing conditions had no significant effects on the surface topography and roughness (Sa value). Various post-curing conditions also had no significant effects on the flexural strength. Notably, the flexural modulus of the WAT group (2671.80 ± 139.42 MPa) was significantly higher than the AIR group (2197.47 ± 197.93 MPa, p = 0.0103). After different post-curing conditions, the water sorption and solubility of the specimens met the ISO standards. Finally, all post-curing conditions effectively reduced cytotoxic effects. SIGNIFICANCES: Post-curing with different oxygen levels improved flexural properties, and flexural modulus significantly increased after the specimens were submerged in water. In addition, water sorption and solubility, and cytocompatibility were optimized by post-curing, irrespective of the post-curing conditions. Therefore, the water-submerged conditions optimized the flexural modulus of the 3D-printed denture base materials.

Zinc based biodegradable metals for bone repair and regeneration: Bioactivity and molecular mechanisms.

Bone fractures and critical-size bone defects are significant public health issues, and clinical treatment outcomes are closely related to the intrinsic properties of the utilized implant materials. Zinc (Zn)-based biodegradable metals (BMs) have emerged as promising bioactive materials because of their exceptional biocompatibility, appropriate mechanical properties, and controllable biodegradation. This review summarizes the state of the art in terms of Zn-based metals for bone repair and regeneration, focusing on bridging the gap between biological mechanism and required bioactivity. The molecular mechanism underlying the release of Zn ions from Zn-based BMs in the improvement of bone repair and regeneration is elucidated. By integrating clinical considerations and the specific bioactivity required for implant materials, this review summarizes the current research status of Zn-based internal fixation materials for promoting fracture healing, Zn-based scaffolds for regenerating critical-size bone defects, and Zn-based barrier membranes for reconstituting alveolar bone defects. Considering the significant progress made in the research on Zn-based BMs for potential clinical applications, the challenges and promising research directions are proposed and discussed.

Influence of additive manufacturing method and build angle on the accuracy of 3D-printed palatal plates.

OBJECTIVES: In this in vitro study, the effects of additive manufacturing (AM) methods and build angles on the trueness and precision of 3D-printed palatal plate orthodontic appliances for newborns and infants were examined. METHODS: Specimens were fabricated by different representative AM methods, including digital light processing (DLP), fused filament fabrication (FFF), and MultiJet printing (MJP). Three build angles (0°, 45°, and 90°) were used. After scanning, all specimens were analyzed using the 3D inspection software. The root mean square values were measured for trueness and precision. Color maps were created to detect deviations in samples. The data were statistically analyzed with a two-way ANOVA. RESULTS: The trueness and precision were statistically influenced by both AM methods and build angles (p < 0.05). Moreover, the root mean square values of the 45° DLP (0.0221 ± 0.0017 µm) and the 0° MJP (0.0217 ± 0.0014 µm) were significantly lower compared to those in other groups (p < 0.001). CONCLUSIONS: AM methods (DLP, FFF, and MJP) and build angles (0°, 45°, and 90°) significantly impacted the dimensional accuracy of additively manufactured palatal plate orthodontic appliances. Also, the 45° DLP and the 0° MJP were associated with the highest trueness and precision. CLINICAL SIGNIFICANCE: All tested AM methods with different build angles yielded clinically acceptable outcomes (within an acceptance range of ±300 µm for trueness), achieving the highest accuracy with a technology-specific suitable build angle.

Cytotoxicity of Biodegradable Zinc and Its Alloys: A Systematic Review.

Zinc-based biodegradable metals (BMs) have been developed for biomedical implant materials. However, the cytotoxicity of Zn and its alloys has caused controversy. This work aims to investigate whether Zn and its alloys possess cytotoxic effects and the corresponding influence factors. According to the guidelines of the PRISMA statement, an electronic combined hand search was conducted to retrieve articles published in PubMed, Web of Science, and Scopus (2013.1-2023.2) following the PICOS strategy. Eighty-six eligible articles were included. The quality of the included toxicity studies was assessed utilizing the ToxRTool. Among the included articles, extract tests were performed in 83 studies, and direct contact tests were conducted in 18 studies. According to the results of this review, the cytotoxicity of Zn-based BMs is mainly determined by three factors, namely, Zn-based materials, tested cells, and test system. Notably, Zn and its alloys did not exhibit cytotoxic effects under certain test conditions, but significant heterogeneity existed in the implementation of the cytotoxicity evaluation. Furthermore, there is currently a relatively lower quality of current cytotoxicity evaluation in Zn-based BMs owing to the adoption of nonuniform standards. Establishing a standardized in vitro toxicity assessment system for Zn-based BMs is required for future investigations.

Post-processing of DLP-printed denture base polymer: Impact of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion.

OBJECTIVES: To investigate the effect of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion of vat-photopolymerization additive-manufacturing denture base polymers. METHODS: The specimens were additively manufactured using digital light processing (DLP). Specimen surfaces were coated with the same printed resin, and mechanical polishing was used for comparison. Surface topography, arithmetical mean height (Sa), and water contact angle values were measured. Furthermore, flexural strength (FS)/modulus and fractography were evaluated. Also, cytotoxicity was evaluated by an extract test. Finally, an adhesion test was used to investigate the adhesion of mixed oral bacteria to the specimens. RESULTS: The Sa values in the polished (0.26 ± 0.08 µm) and coated (0.38 ± 0.14 µm) groups were significantly lower than in the untreated (2.21 ± 0.42 µm) and control (2.01 ± 0.37 µm) groups. The coating treatment resulted in a higher FS compared to the untreated surface (p = 0.0002). After the coating treatment, no significant differences were found in relative cell viability between the groups (p > 0.05). The quantitative results showed significantly higher bacterial adhesion in the untreated group than in the polished (p = 0.0047) and coated (p < 0.0001) groups. SIGNIFICANCE: The surface characteristics and flexural properties were optimized by the protective coating. Also, the protective coating did not adversely affect cytocompatibility. Moreover, the coating treatment could effectively decrease oral bacteria adhering to the surfaces. Therefore, the protective coating treatment can be a less time-consuming alternative to mechanical polishing as a post-processing procedure for the digital denture.

Denture wearing status, cardiovascular health profiles, and mortality in edentulous patients: A prospective study with a 27-year follow-up.

OBJECTIVES: Life's Simple 7 (LS7) metrics provide insight into improving cardiovascular health (CVH) and help reduce mortality risks. Edentulous older adults have a higher mortality risk than dentulous ones, probably due to worse oral function. It is reported that wearing dentures will decrease the mortality risk factor by improving oral function. This prospective study aimed to investigate if denture wearing could modify the association between CVH profile and mortality risk among edentulous elderly. METHODS: From the Third National Health and Nutrition Examination Survey (NHANES III), 1,735 edentulous older adults (mean age 69.4 years old) with CVH profiles and data on denture wearing status were selected for this study. CVH profiles according to LS7 metrics were classified into poor, intermediate, or ideal. Denture wearers were defined as those wearing complete dentures in both arches all the time or only when awake. Multivariable Cox proportional-hazards regression was conducted to estimate the association of CVH profiles with all-cause and cardiovascular mortality. Stratified analyses and the testing of interaction terms were used to evaluate the difference between the association in edentulous patients with and without dentures. RESULTS: A total of 1,420 (81.8%) older adults died during the 27-year follow-up, with 478 (27.6%) cases attributable to heart disease. After controlling for potential confounders, edentulous patients with an ideal CVH (LS7 = 10-14) had a lower mortality risk than those with poor CVH (LS7 = 0-4). Furthermore, we observed an effect modification by denture use (Pinteraction = 0.046), with the role of ideal CVH in mitigating mortality among the denture wearers (Hazard Ratio = 0.440 [0.329-0.588]), while no significant association among those without dentures. Similar results were achieved for cardiovascular mortality, but there was no effect modification of denture use (Pinteraction = 0.352). CONCLUSION: In this study, a favorable cardiovascular health profile presents a protective effect on all-cause mortality only among edentulous patients wearing dentures instead of non-wearer. CLINICAL SIGNIFICANCE: Denture usage could improve oral function (e.g., chewing, smiling, speaking, etc.) and promote general health. Effect modification found in this study indicates having ideal CVH alone cannot substantially reduce mortality risk among edentulous patients. Therefore, health care professionals should keep an eye on the elderly not wearing dentures as they are probably more at risk for adverse health outcomes. It remains unclear if denture wearing has a causal relation with lower mortality risks, and further research is needed.

Influence of Surface Roughness on Biodegradability and Cytocompatibility of High-Purity Magnesium.

High-purity magnesium (Mg) is a promising biodegradable metal for oral and maxillofacial implants. Appropriate surface roughness plays a critical role in the degradation behavior and the related cellular processes of biodegradable Mg-based metals. Nevertheless, the most optimized surface roughness has been questionable, especially for Mg-based oral and maxillofacial implants. Three representative scales of surface roughness were investigated in this study, including smooth (Sa < 0.5 µm), moderately rough (Sa between 1.0−2.0 µm), and rough (Sa > 2.0 µm). The results indicated that the degradation rate of the Mg specimen in the cell culture medium was significantly accelerated with increased surface roughness. Furthermore, an extract test revealed that Mg with different roughness did not induce an evident cytotoxic effect. Nonetheless, the smooth Mg surface had an adversely affected cell attachment. Therefore, the high-purity Mg with a moderately rough surface exhibited the most optimized balance between biodegradability and overall cytocompatibility.

mTOR participates in the formation, maintenance, and function of memory CD8+T cells regulated by glycometabolism.

Memory CD8+T cells participate in the fight against infection and tumorigenesis as well as in autoimmune disease progression because of their efficient and rapid immune response, long-term survival, and continuous differentiation. At each stage of their formation, maintenance, and function, the cell metabolism must be adjusted to match the functional requirements of the specific stage. Notably, enhanced glycolytic metabolism can generate sufficient levels of adenosine triphosphate (ATP) to form memory CD8+T cells, countering the view that glycolysis prevents the formation of memory CD8+T cells. This review focuses on how glycometabolism regulates memory CD8+T cells and highlights the key mechanisms through which the mammalian target of rapamycin (mTOR) signaling pathway affects memory CD8+T cell formation, maintenance, and function by regulating glycometabolism. In addition, different subpopulations of memory CD8+T cells exhibit different metabolic flexibility during their formation, survival, and functional stages, during which the energy metabolism may be critical. These findings which may explain why enhanced glycolytic metabolism can give rise to memory CD8+T cells. Modulating the metabolism of memory CD8+T cells to influence specific cell fates may be useful for disease treatment.

Impact of sterilization treatments on biodegradability and cytocompatibility of zinc-based implant materials.

Biodegradable zinc (Zn) and Zn-based alloys have been recognized as promising biomaterials for biomedical implants. Sterilization is an essential step in handling Zn-based implants before their use in clinical practice and there are various sterilization methods are available. However, how these treatments influence the Zn-based biomaterials remains unknown and is of critical relevance. In this study, three commonly-applied standard sterilization methods, namely gamma irradiation, hydrogen peroxide gas plasma and steam autoclave, were used on pure Zn and Zn3Cu (wt%) alloy. The treated Zn and ZnCu alloy were investigated to compare the different influences of sterilizations on surface characteristics, transient and long-term degradation behavior and cytotoxicity of Zn and Zn alloy. Our results indicate that autoclaving brought about apparently a formation of inhomogeneous zinc oxide film whereas the other two methods produced no apparent alterations on the material surfaces. Consequently, the samples after autoclaving showed significantly faster degradation rates and more severe localized corrosion, especially for the ZnCu alloy, owing to the incomplete covering and unstable zinc oxide layer. Moreover, the autoclave-treated Zn and ZnCu alloy exhibited apparent cytotoxic effects towards fibroblasts, which may be due to the excessive Zn ion releasing and its local concentration exceeds the cellular tolerance capacity. In contrast, gamma irradiation and hydrogen peroxide gas plasma had no apparent adverse effects on the biodegradability and cytocompatibility of Zn and ZnCu alloy. Our findings may have significant implications regarding the selection of suitable sterilization methods for Zn-based implant materials among others.

Jaw Periosteal Cells Seeded in Beta-Tricalcium Phosphate Inhibit Dendritic Cell Maturation.

Mesenchymal stem cells (MSCs) have gained attraction not only in the field of regenerative medicine but also in the field of autoimmune disease therapies or organ transplantation due to their immunoregulatory and/or immunosuppressive features. Dendritic cells (DCs) play a crucial role in initiating and regulating immune reactions by promoting antigen-specific T cell activation. In this study, we investigated the effect of human jaw periosteal progenitor cells (JPCs) seeded in beta-tricalcium phosphate (ß-TCP) scaffolds on monocyte-derived DC differentiation. Significantly lower numbers of differentiated DCs were observed in the presence of normal (Co) and osteogenically induced (Ob) JPCs-seeded ß-TCP constructs. Gene expression analysis revealed significantly lower interleukin-12 subunit p35 (IL-12p35) and interleukin-12 receptor beta 2 (IL-12Rß2) and pro-inflammatory cytokine interferon-gamma (IFN-γ) levels in DCs under Ob conditions, while interleukin-8 (IL-8) gene levels were significantly increased. Furthermore, in the presence of JPCs-seeded ß-TCP constructs, interleukin-10 (IL-10) gene expression was significantly induced in DCs, particularly under Ob conditions. Analysis of DC protein levels shows that granulocyte-colony stimulating factor (G-CSF) was significantly upregulated in coculture groups. Our results indicate that undifferentiated and osteogenically induced JPCs-seeded ß-TCP constructs have an overall inhibitory effect on monocyte-derived DC maturation.

Mechanical Behavior of Single Patch Composite Repaired Al Alloy Plates: Experimental and Numerical Analysis.

In this paper, glass fiber reinforced polymer (GFRP) materials were used to repair cracked Al plates. In order to study the influences of resin properties and repair configurations, three resins and two patch configurations were selected to manufacture six groups of specimens. It turned out that only little differences (less than 3%) were found in tensile strength among the six groups. Compared with the parent plates, the strength recovery ratio was higher than 80% after the GFRP repair, representing excellent repair efficiency. Moreover, a finite element model (FEM) was established to analyze the failure process of the repaired structure under tensile loading. The FEM results show good agreement with the experimental results, indicating good precision. Both the experimental and numerical work found that the damage initiated in the plies adjacent to the crack surface and the failure modes was mainly delamination and fiber breakage. This work will be meaningful for the future application of GFRP in metallic structures.

Response of human periosteal cells to degradation products of zinc and its alloy.

Zinc (Zn) and its alloys are proposed as promising resorbable materials for osteosynthesis implants. Detailed studies should be undertaken to clarify their properties in terms of degradability, biocompatibility and osteoinductivity. Degradation products of Zn alloys might affect directly adjacent cellular and tissue responses. Periosteal stem cells are responsible for participating in intramembranous ossification during fracture healing. The present study aims at examining possible effects emanating from Zn or Zn-4Ag (wt%) alloy degradation products on cell viability and osteogenic differentiation of a human immortalized cranial periosteal cell line (TAg cells). Therefore, a modified extraction method was used to investigate the degradation behavior of Zn and Zn-4Ag alloys under cell culture conditions. Compared with pure Zn, Zn-4Ag alloy showed almost fourfold higher degradation rates under cell culture conditions, while the associated degradation products had no adverse effects on cell viability. Osteogenic induction of TAg cells revealed that high concentration extracts significantly reduced calcium deposition of TAg cells, while low concentration extracts enhanced calcium deposition, indicating a dose-dependent effect of Zn ions. Our results give evidence that the observed cytotoxicity effects were determined by the released degradation products of Zn and Zn-4Ag alloys, rather than by degradation rates calculated by weight loss. Extracellular Zn ion concentration was found to modulate osteogenic differentiation of TAg cells. These findings provide significant implications and guidance for the development of Zn-based alloys with an optimized degradation behavior for Zn-based osteosynthesis implants.

3D hollow nanoflowers assembled by ultrathin molybdenum-nickel phosphide nanosheets as robust electrocatalysts for oxygen evolution reaction.

Designing cost-efficient and durable electrocatalysts toward oxygen evolution reaction (OER) has been of vital significance for the commercial development of various renewable energy systems. Herein, we report the construction of a new class of 3D hollow nanoflower catalysts that assembled by ultrathin nickel-molybdenum phosphide nanosheets. Owing to the increased electronic and ion transport channels, the heteroatom doping, and synergistic effects from the interconnected compositions, the newly-generated 3D MoNiP hollow nanoflowers display superior OER activity than that of Ir/C. And the optimized Mo1Ni1P hollow nanoflowers (Mo1Ni1P HNFs) can afford a current density of 10 mA cm-2 at the overpotential of 275 mV in 1.0 M KOH solution. More importantly, the resultant Mo1Ni1P HNFs also display excellent stability with negligible activity and morphology decay. This work provides insights for the utilization of earth-abundant and highly efficient electrocatalysts via rationally designing the morphology of electrocatalysts.

One-step synthesis of hexylresorcinol calix[4]arene-capped ZnO-Ag nanocomposites for enhanced degradation of organic pollutants.

In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO-Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag+ to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO-Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO-Ag nanocomposites. HRCA-capped ZnO-Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that O2- and h+ are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO-Ag nanocomposite system. HRCA-capped ZnO-Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.

Investigation of zinc­copper alloys as potential materials for craniomaxillofacial osteosynthesis implants.

In this study, zinc­copper (ZnCu) alloys were investigated regarding their feasibility as absorbable metals for osteosynthesis implants, especially in the craniomaxillofacial area. Mechanical properties and in vitro corrosion behavior of as-rolled Zn-xCu (x = 1, 2 and 4 wt%) alloys were systematically evaluated and screened. The as-rolled Zn4Cu alloy had mechanical properties that were superior to the most absorbable craniomaxillofacial osteosynthesis materials recently reported. The addition of Cu to Zn showed to have no apparent effect on the corrosion rates of the samples. The rolling process on Zn and Zn1Cu resulted in more uniform corrosion than on as-cast counterparts after 28 days immersion. Furthermore, the Zn4Cu alloys exhibited no apparent cytotoxic effect towards L929, TAg or Saos-2 cells. Proliferation rates of TAg and Saos-2 cells were shown to be activated by specific Zn ion concentrations in the as-rolled Zn4Cu alloy extracts. Analysis of in vitro antibacterial properties revealed that the as-rolled Zn4Cu alloy possessed the potential to inhibit biofilm formation of mixed oral bacteria. We conclude that the as-rolled Zn4Cu alloy might be a promising material for fabrication of craniomaxillofacial osteosynthesis implants.