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.
This study aims to determine the occurrence and behavior of five classes of 20 antibiotics in both water and sedimentary phases in the Huangpu River, which supplies drinking water to Shanghai City, ...China. Of the 20 antibiotics, sulfonamides showed the highest concentrations in water samples (34-859 ng L(-1)) while tetracyclines (average concentration at 18 μg kg(-1) dry weight) and macrolides (12 μg kg(-1) dry weight) dominated in sediment samples. The spatial distribution of antibiotics showed that the main polluting sources into the river were animal farming sites and the tributaries downstream of the Yuanxie River. In addition, linear relationships between logKoc and logKow, and between logKoc and log molecular weight, were demonstrated, suggesting the importance of contaminant properties in inter-phase behavior. The environmental risk assessment revealed that some antibiotics, in particular sulfamethoxazole could cause medium damage to daphnid in the aquatic ecosystem.
Antibiotics as emerging contaminants are of global concern due to the development of antibiotic resistant genes potentially causing superbugs. Current wastewater treatment technology cannot ...sufficiently remove antibiotics from sewage, hence new and low-cost technology is needed. Adsorptive materials have been extensively used for the conditioning, remediation and removal of inorganic and organic hazardous materials, although their application for removing antibiotics has been reported for ~30 out of 250 antibiotics so far. The literature on the adsorptive removal of antibiotics using different adsorptive materials is summarized and critically reviewed, by comparing different adsorbents with varying physicochemical characteristics. The efficiency for removing antibiotics from water and wastewater by different adsorbents has been evaluated by examining their adsorption coefficient (Kd) values. For sulfamethoxazole the different adsorbents followed the trend: biochar (BC)>multi-walled carbon nanotubes (MWCNTs)>graphite=clay minerals, and for tetracycline the adsorptive materials followed the trend: SWCNT>graphite>MWCNT=activated carbon (AC)>bentonite=humic substance=clay minerals. The underlying controlling parameters for the adsorption technology have been examined. In addition, the cost of preparing adsorbents has been estimated, which followed the order of BCs<ACs<ion exchange resins<MWCNTs<SWCNTs. The future research challenges on process integration, production and modification of low-cost adsorbents are elaborated.
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•Adsorptive materials with different physicochemical properties are reviewed.•Applications of adsorbents for antibiotic removal from wastewater are assessed.•Integration of adsorptive process to the existing treatment has been proposed.•Regeneration of adsorptive materials and associated costs have been discussed.•Challenges for further research in adsorptive materials are elaborated.
•Emerging contaminant removal technologies have been summarized.•MBR, microalgae and activated sludge are effective biological removal processes.•Ozonation/H2O2 and photo-Fenton are highly effective ...chemical removal processes.•Many hybrid systems have enhanced removal capacity of emerging contaminants.•Future research regarding emerging contaminant removal has been proposed.
This review focuses on the removal of emerging contaminants (ECs) by biological, chemical and hybrid technologies in effluents from wastewater treatment plants (WWTPs). Results showed that endocrine disruption chemicals (EDCs) were better removed by membrane bioreactor (MBR), activated sludge and aeration processes among different biological processes. Surfactants, EDCs and personal care products (PCPs) can be well removed by activated sludge process. Pesticides and pharmaceuticals showed good removal efficiencies by biological activated carbon. Microalgae treatment processes can remove almost all types of ECs to some extent. Other biological processes were found less effective in ECs removal from wastewater. Chemical oxidation processes such as ozonation/H2O2, UV photolysis/H2O2 and photo-Fenton processes can successfully remove up to 100% of pesticides, beta blockers and pharmaceuticals, while EDCs can be better removed by ozonation and UV photocatalysis. Fenton process was found less effective in the removal of any types of ECs. A hybrid system based on ozonation followed by biological activated carbon was found highly efficient in the removal of pesticides, beta blockers and pharmaceuticals. A hybrid ozonation-ultrasound system can remove up to 100% of many pharmaceuticals. Future research directions to enhance the removal of ECs have been elaborated.
Coherence distillation is one of the central problems in the resource theory of coherence. In this Letter, we complete the deterministic distillation of quantum coherence for a finite number of ...coherent states under strictly incoherent operations. Specifically, we find the necessary and sufficient condition for the transformation from a mixed coherent state into a pure state via strictly incoherent operations, which recovers a connection between the resource theory of coherence and the algebraic theory of majorization lattice. With the help of this condition, we present the deterministic coherence distillation scheme and derive the maximum number of maximally coherent states obtained via this scheme.
Novel mechanisms for electromagnetic wave emission in the terahertz frequency regime emerging at the nanometer scale have recently attracted intense attention for the purpose of searching ...next-generation broadband THz emitters. Here, we report broadband THz emission, utilizing the interface inverse Rashba-Edelstein effect. By engineering the symmetry of the Ag/Bi Rashba interface, we demonstrate a controllable THz radiation (∼0.1-5 THz) waveform emitted from metallic Fe/Ag/Bi heterostructures following photoexcitation. We further reveal that this type of THz radiation can be selectively superimposed on the emission discovered recently due to the inverse spin Hall effect, yielding a unique film thickness dependent emission pattern. Our results thus offer new opportunities for versatile broadband THz radiation using the interface quantum effects.
Dissimilar lap joints of 1060 aluminum and T2 copper were obtained by friction stir spot welding (FSSW) at various rotational speeds. The measured process variables during welding revealed that an ...increasing rotational speed leads to a higher peak temperature but a lower torque and plunging force due to the greater softening degree of material. A continuous CuAl2-CuAl-Al4Cu9 laminated layer developed at the Al-Cu interface under the highest rotational speed, while the interface was characterized by the interruptedly distributed CuAl2 layer under lower rotational speeds. Intermetallic compound (IMC) formation sequence for CuAl2, CuAl and Al4Cu9 was predicted according to thermodynamic principles, which is consistent with the interfacial microstructure evolution identified by the transmission electron microscope (TEM). Besides the metallurgical bonding through the IMC layer at the Al-Cu interface, joints have a Cu hook extruded upward by the pin tool from the lower Cu sheet into the upper Al sheet, which provided additional mechanical interlocking between the sheets. Tensile properties of the joints were closely related to the thickness of the IMC layer and geometric features of the hook, higher tensile properties were found in joints owning a continuous interfacial IMC layer with a proper thickness as well as a high penetration depth of the hook into the upper Al sheet.
•A higher rotational speed leads to a lower torque and plunging force.•CuAl2-CuAl-Al4Cu9 laminated layer forms at the hook interface at high heat input.•IMC formation sequence for CuAl2, CuAl and Al4Cu9 is predicted.•The joints are both metallurgical and mechanical bonded.•Hook morphology influences fracture path and shear strength.
Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue ...is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.
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•Key influences are canyon geometry, traffic and weather conditions, and chemical reactions.•Traffic interventions in street canyons lead to moderate improvement of roadside air quality.•Well-designed canyon geometry significantly enhances dispersion of emissions.•Combining solid and porous in-street barriers is more effective than individual use.•Traffic control and in-street barriers are more implementable than canyon geometry design.
Aims. We use high-resolution continuum images obtained with the Atacama Large Millimeter Array (ALMA) to probe the surface density of star formation in z ~ 2 galaxies and study the different physical ...properties between galaxies within and above the star-formation main sequence of galaxies. Methods. We use ALMA images at 870 μm with 0.2 arcsec resolution in order to resolve star formation in a sample of eight star-forming galaxies at z ~ 2 selected among the most massive Herschel galaxies in the GOODS-South field. This sample is supplemented with eleven galaxies from the public data of the 1.3 mm survey of the Hubble Ultra-Deep Field, HUDF. We derive dust and gas masses for the galaxies, compute their depletion times and gas fractions, and study the relative distributions of rest-frame ultraviolet (UV) and far-infrared (FIR) light. Results. ALMA reveals systematically dense concentrations of dusty star formation close to the center of the stellar component of the galaxies. We identify two different starburst regimes: (i) the classical population of starbursts located above the SFR-M⋆ main sequence, with enhanced gas fractions and short depletion times and (ii) a sub-population of galaxies located within the scatter of the main sequence that experience compact star formation with depletion timescales typical of starbursts of ~150 Myr. In both starburst populations, the FIR and UV are distributed in distinct regions and dust-corrected star formation rates (SFRs) estimated using UV-optical-near-infrared data alone underestimate the total SFR. Starbursts hidden in the main sequence show instead the lowest gas fractions of our sample and could represent the last stage of star formation prior to passivization. Being Herschel-selected, these main sequence galaxies are located in the high-mass end of the main sequence, hence we do not know whether these “starbursts hidden in the main sequence” also exist below 1011 M⊙. Active galactic nuclei (AGNs) are found to be ubiquitous in these compact starbursts, suggesting that the triggering mechanism also feeds the central black hole or that the active nucleus triggers star formation.
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