Abstract Objective Multi-mode universal adhesives offer clinicians the choice of using the etch-and-rinse technique, selective enamel etch technique or self-etch technique to bond to tooth ...substrates. The present study examined the short-term in vitro performance of five universal adhesives bonded to human coronal dentine. Methods Two hundred non-carious human third molars were assigned to five groups based on the type of the universal adhesives (Prime&Bond Elect, Scotchbond Universal, All-Bond Universal, Clearfil Universal Bond and Futurabond U). Two bonding modes (etch-and-rinse and self-etch) were employed for each adhesive group. Bonded specimens were stored in deionized water for 24 h or underwent a 10,000-cycle thermocycling ageing process prior to testing ( N = 10). Microtensile bond testing (μTBS), transmission electron microscopy (TEM) of resin–dentine interfaces in non-thermocycled specimens and scanning electron microscopy (SEM) of tracer-infused water-rich zones within hybrid layers of thermocycled specimens were performed. Results Both adhesive type and testing condition (with/without thermocycling) have significant influences on μTBS. The use of each adhesive in either the etch-and-rinse or self-etch application mode did not result in significantly different μTBS to dentine. Hybrid layers created by these adhesives in the etch-and-rinse bonding mode and self-etch bonding mode were ∼5 μm and ≤0.5 μm thick respectively. Tracer-infused regions could be identified within the resin–dentine interface from all the specimens prepared. Conclusion The increase in versatility of universal adhesives is not accompanied by technological advances for overcoming the challenges associated with previous generations of adhesives. Therapeutic adhesives with bio-protective and bio-promoting effects are still lacking in commercialized adhesives. Clinical significance Universal adhesives represent manufacturers’ attempt to introduce versatility in product design via adaptation of a single-bottle self-etch adhesive for other application modes without compromising its bonding effectiveness.
The mineral and organic phases of mineralized dentin contribute co-operatively to its strength and toughness. This study tested the null hypothesis that there is no difference in nano-dynamic ...mechanical behavior (complex modulus-E*; loss modulus-E′′; storage modulus-E′; in GPa) of dentin hybrid layers (baseline: E*, 3.86 ± 0.24; E′′, 0.23 ± 0.05; E′, 3.85 ± 0.24) created by an etch-and-rinse adhesive in the presence or absence of biomimetic remineralization after in vitro aging. Using scanning probe microscopy and nano-dynamic mechanical analysis, we demonstrated that biomimetic remineralization restored the nano-dynamic mechanical behavior of heavily remineralized, resin-sparse regions of dentin hybrid layers (E*, 19.73 ± 3.85; E′′, 8.75 ± 3.97; E′, 16.02 ± 2.58) to those of the mineralized dentin base (E*, 19.20 ± 2.42; E′′, 6.57 ± 1.96; E′, 17.39 ± 2.0) p > 0.05. Conversely, those resin-sparse, water-rich regions degraded in the absence of biomimetic remineralization, with significant decline p < 0.05 in their complex and storage moduli (E*, 0.83 ± 0.35; E′′, 0.88 ± 0.24; E′, 0.62 ± 0.32). Intrafibrillar apatite deposition preserves the integrity of resin-sparse regions of hybrid layers by restoring their nanomechanical properties to those exhibited by mineralized dentin.
► We reviewed four practical projects with radiant heating/cooling in Mainland China. ► Existing different considerations in the system design methods are presented. ► The factors affecting the ...energy efficiency are identified. ► Monitoring actual energy used and developing design methods are recommended for further studies.
A number of radiant heating/cooling systems have been applied in Mainland China in recent years for its improved thermal comfort and inherent energy saving potential. Because the systems require relatively higher temperatures for cooling and lower temperatures for heating, many natural low-grade energy sources can be directly or indirectly used. However, because of a lack of information about prior practical projects, a number of difficulties in design, construction and management of the systems have been encountered, and energy efficiency is not necessarily achieved in all situations. This paper reviews the practical applications in four major projects involving different building types located in different climatic cities and presents the associated considerations in system design. Other factors affecting the energy efficiency of the systems are identified, such as the spatial convection and radiation heat transfer processes in indoor environments and the envelope thermal properties. Further studies are needed to achieve system optimization and to realize the full energy saving potentials of radiant systems by developing analytical design methods and monitoring the actual energy use of such systems in completed projects.
A numerical wind tunnel model was proposed. The computed results of the pollutant diffusion around a typical Hong Kong high-rise building model (at a linear scale of 1:30), were found to show a ...similar trend to the outcomes of self-conducted experimental measurements that the pathways of pollutant migration for windward and leeward pollutant emission are different. For the case with windward pollutant emission at the 3rd floor within a re-entry, the pollutant migrated downwards due to the downwash created by the wind. In contrast, for the case with leeward pollution emission, dispersion is dominated by intense turbulent mixing in the near wake and characterized by the upward migration of the pollutant in the leeward re-entry. The simulated results of haze-fog (HF) studies confirm that the pathway of pollutant migration is dominated by wind–structure interaction and buoyancy effect only plays a minor role in the dispersion process.
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•A self-developed numerical wind tunnel model was proposed.•Characteristics of air pollutant dispersion with windward/leeward emission were discussed.•Wind–structure interaction controls the air pollutant dispersion around the building.
The different characteristics of air pollutant dispersion around a high-rise building, for both cases of a dispersion source in either the windward face or leeward face, are dominated by wind–structure interaction, with buoyancy effect playing only a minor role.
Abstract Objective The present study examined the effect of a quaternary ammonium silane (QAS) cavity disinfectant on the viability of human dental pulp cells, dentine bond durability and nanoleakage ...of simplified etch-and-rinse adhesives. Methods Etched dentine surface of third molars were randomly divided into two adhesive groups, Adper™ Single Bond 2 and Prime & Bond® NT™. For each adhesive, the teeth were randomly assigned to five cavity disinfectant groups ( N = 6): Group 1: deionised water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS and Group 5: 10% QAS. The cavity disinfectants were applied on etched dentine surfaces for 20 s, followed by adhesive application. The bonded teeth were sectioned for bond strength testing at 24 h, 6 months and 12 months. Viability of human dental pulpal cells was examined using MTT assay. Bond strength data were analysed using 3-way ANOVA and Tukey test. Interfacial nanoleakage was evaluated after 24 h and 12 months and analysed using Kruskal–Wallis test. Results Significant differences in bond strength were observed for the factors disinfectants ( p < 0.001) and time ( p < 0.001); while the factor, adhesive, was not significantly different ( p = 0.203). The 2% QAS cavity disinfectant preserved bond strength of both adhesives and reduced interfacial nanoleakage after 12 months. Cell viability was the lowest for 2% CHX, followed by 2% QAS and the control. Conclusions The 2% QAS cavity disinfectant demonstrated greater cell viability compared to 2% CHX, with no adverse effect on immediate bond strength and preserved bond stability over time. Clinical significance Incorporation of 2% quaternary ammonium silane cavity disinfectant in the resin–dentine bonding protocol enhances the success rate of bonded restorations.
•Dynamic stress redistribution resulted from transient unloading due to excavation is considered.•The 2D numerical simulation on excavation damaged zone induced by dynamic stress redistribution is ...conducted.•Damage zone induced by transient unloading is only in the 20% diameter vicinity of excavation perimeter.
The formation of an excavation damaged zone (EDZ) around an opening in a deep rock mass is associated with the dynamic stress redistribution that starts from transient release of high in situ stress to the final quasi-static stress state after the excavation. This study applies a theoretical analysis of stress redistribution due to transient unloading in surrounding rock under hydrostatic stress field, and develops a numerical elastodynamics model for finite element analysis. Coupling the theoretical and the numerical solutions, a general damage model for heterogeneous rock mass is proposed by taking the dynamic stress redistribution due to excavation into account. Finally, the dynamic stress redistribution, as well as the induced damage zone around the excavation under different lateral pressure coefficients is numerically simulated. The numerical result indicates that, the stress wave induced by the transient unloading will initially cause the damage only in the 1/3 radius vicinity of excavation perimeter. The damage zone may then develop further under the constant quasi-static far-field stress. Therefore, the EDZ development during deep excavation is closely dependent on in situ stress, rock strength and excavation method.
Peri-implant infra-bony defects are difficult to treat, and data on the management of peri-implantitis are lacking. The aim of this study was to evaluate the effect of a combined surgical approach to ...manage peri-implantitis: implantoplasty with xenogeneic bone grafting and a concentrated growth factor membrane. Two independent examiners analysed the medical records and radiographs taken before surgery and at the last follow-up. Data were analysed at the implant level; some patient-level data (age, sex, smoking habit) were also considered. Linear regression analysis with generalized estimating equations (GEE) was used to explore the effect of variables of interest (including marginal bone level (MBL)) on implantitis treatment success and resolution rates. The effect of the prosthesis type on postoperative clinical and radiographic parameters was also explored by GEE, with adjustment for age, sex, tooth site, location, follow-up duration, and implant length (model IV including all). Thirty patients with 72 implants were investigated. The implant survival rate was 100% over a mean observation period of 3.3 years (range 2–11 years). The treatment success rate (bone loss <0.5 mm, no bleeding on probing (BOP), no suppuration, probing depth (PD) < 5 mm) was higher in females than males (50% vs 19.0%; P = 0.008). At the last postoperative follow-up, the MBL (1.51 ± 1.07 vs 4.01 ± 1.13 mm), PD (3.61 ± 0.84 vs 6.54 ± 1.01 mm), and BOP (23.38 ± 23.18% vs 79.17 ± 15.51%) were significantly reduced when compared to pre-surgery values (all P < 0.001). Furthermore, a significantly higher PD reduction (β = −1.10 mm, 95% confidence interval −1.97 to −0.23 mm, P = 0.014) was observed for implants with a single crown than a full-arch prosthesis (GEE model IV). Preliminary clinical and radiographic data indicate that implantoplasty in combination with surgery could be an effective treatment option for peri-implantitis.
A novel HPLC method for simultaneous detecting bulky imides and their hydrolyzed products by D-hydantoinase was established. Phthalimide (PI) and 2,3-pyridinedicarboximide (PDI) can be ...regiospecifically hydrolyzed by engineered strain pET3a-hyd/
Escherichia coli
BL21(DE3) expressed D-hydantoinase into phthalamic acid (PA) and 3-carbamoyl-α-picolinic acid (α-3CP). The processes were analyzed by HPLC with H
2
O-acetonitrile as mobile phase containing 0.1% (v/v) trifluoroacetic acid at 254 nm (PDI, α‑3CP and β-2CP) and 220 nm (PI and PA) detector wavelength, respectively. The specific activities of the engineered strain account for 0.15 U/(mL × 10 OD
600
) to PI and 0.61 U/(mL × 10 OD
600
) to PDI.
MiR-133 was found to be specifically expressed in cardiac and skeletal muscle in previous studies. There are two members in the miR-133 family: miR-133a and miR-133b. Although previous studies ...indicated that miR-133a was related to myogenesis, the signaling pathways regulated by miR-133 were still not very clear. In this study, we showed that both miR-133a and miR-133b were upregulated during myogenesis through Solexa sequencing. We confirmed that miR-133 could promote myoblast differentiation and inhibit cell proliferation through the regulation of the extracellular signal-regulated kinase (ERK) signaling pathway in C2C12 cells. FGFR1 and PP2AC, which both participate in signal transduction of the ERK1/2 pathway, were found to be negatively regulated by miR-133a and miR-133b at the post-transcriptional level. Also, downregulation of ERK1/2 phosphorylation by miR-133 was detected. FGFR1 and PP2AC were also found to repress C2C12 differentiation by specific siRNAs. In addition, we found that inhibition of ERK1/2 pathway activity can inhibit C2C12 cell proliferation and promote the initiation of differentiation but form short and small myotubes. Furthermore, we found that the expression of miR-133 was negatively regulated by ERK1/2 signaling pathway. In summary, we demonstrated the role of miR-133 in myoblast and further revealed a new feedback loop between miR-133 and the ERK1/2 signaling pathway involving an exquisite mechanism for regulating myogenesis.
The failure process of rock subjected to combined static and dynamic loading constitutes the mechanism of many engineering applications such as rockburst prediction, rock fragmentation, as well as ...rock drilling and blasting. In this study, the basic principle for simulating the damage and failure process of rock under combined static and dynamic loading is introduced, and it is implemented into RFPA-Dynamics (Rock Failure Process Analysis for Dynamics), a finite element package to analyze the failure process of rock-like media subjected to dynamic loading. The extended RFPA-Dynamics code is firstly validated by simulating the stress distribution and damage evolution in rock specimens during conventional SHPB (Split Hopkinson Pressure Bar) tests. Then, it is utilized to simulate the failure process of rock under combined static and dynamic SHPB tests, and the effects of axial static stress and dynamic stress on the damage and failure process of rock are examined. The strength increase factor (SIF) under combined static and dynamic loading, depending on the rock heterogeneity, static stress and strain rate, is predicted using numerical simulations, and the mechanisms associated with the increase of dynamic strength of rock subjected to the combined static and dynamic loading are clarified. The rock strength predicted with numerical simulations, which is closely related to the rock heterogeneity, is in qualitative agreement with that observed in laboratory SHPB tests, although the predicted rock strength under combined static and dynamic loading is still lower than those from experiments.
► The extended RFPA-Dynamics code is validated for simulating the rock failure under SHPB test. ► The mechanism for dynamic strength variation under combined static and dynamic loading is clarified. ► The dynamic strength that is affected by the rock heterogeneity and static pre-compression is predicted.
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