The clinic applications of bioabsorbable magnesium (Mg) and its alloys have been significantly restricted owing to their poor corrosion resistance. Besides elemental alloying, surface modification ...and functionality is a major approach to increasing corrosion resistance for magnesium alloys. This article reviews the cutting-edge advances and progress of biodegradable surface coatings upon Mg alloys over the last decades, aims to build up a knowledge framework of surface modification on biodegradable Mg alloys. A considerable number of conversion, deposition, mechanical and functional coatings and their preparation methods are discussed. The emphasis has been placed on the composition of chemical conversion and deposited coatings to overcome the disadvantages of adhesion, corrosion resistance and biocompatibility of a single coating for biomedical materials. The issues have been addressed on the integration of the structural and functional factors of the composite coatings.
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•Preparation of ENFMs and their adsorption for heavy metals in water are reviewed.•ENFMs are classified and adsorption capacities of different ENFMs are summarized.•Surface ...modification and organic/inorganic composite ENFMs are research hotspots.•Adsorption mechanism and influencing factor of ENFMs for heavy metal are discussed.•Current challenges, future research and application prospects are highlighted.
Electrospun nanofibrous membranes (ENFMs) have many superior advantages, such as large specific surface area, high porosity, easy modification, good flexibility, and easy separation for recycling, which are consider as excellent adsorbents. In this paper, the research progress in the adsorption of heavy metals in water treatment by ENFMs is reviewed. Three types of ENFMs, including organic polymer ENFMs, organic polymer/inorganic material composite ENFMs and inorganic ENFMs are summarized, and their adsorption capacities for heavy metals in water are compared. The adsorption selectivity and capacity of ENFMs for heavy metals are depended largely on the type and number of functional groups on the surface of membranes, and usually the more the functional groups, the higher the adsorption capacity. The adsorption mechanisms of ENFMs are also mainly determined by the type of functional groups on the membrane. At present, the main challenge is to achieve the mass production of high-quality nanofibers and their actual application in the treatment of heavy metal-containing wastewater. Therefore, more consideration should be focused on the improvement of stability, mechanical strength and reusability of ENFMs. This review may provide an insight for the development of ENFMs-based adsorbents for heavy metals separation and water purification in the future.
Physical Properties of 5 Root Canal Sealers Zhou, Hui-min, PhD; Shen, Ya, DDS, PhD; Zheng, Wei, PhD ...
Journal of endodontics,
10/2013, Letnik:
39, Številka:
10
Journal Article
Recenzirano
Abstract Introduction The aim of this study was to evaluate the pH change, viscosity and other physical properties of 2 novel root canal sealers (MTA Fillapex and Endosequence BC) in comparison with ...2 epoxy resin-based sealers (AH Plus and ThermaSeal), a silicone-based sealer (GuttaFlow), and a zinc oxide-eugenol–based sealer (Pulp Canal Sealer). Methods ISO 6876/2001 specifications were followed. The pH change of freshly mixed and set sealers was evaluated during periods of 1 day and 5 weeks, respectively. The viscosity was investigated at different injection rates (72, 10, and 5 mm/min) at room temperature by using a syringe-based system that was based on the Instron 3360 series universal testing system. Results The flow, dimensional change, solubility, and film thickness of all the tested sealers were in agreement with ISO 6876/2001 recommendations. The MTA Fillapex sealer exhibited a higher flow than the Endosequence BC sealer ( P < .05). The MTA Fillapex and Endosequence BC sealers showed the highest film thicknesses among the tested samples. The Endosequence BC sealer exhibited the highest value of solubility, which was in accordance with 3% mass fraction recommended by the ISO 6876/2001, and showed an acceptable dimensional change. The MTA Fillapex and Endosequence BC sealers presented an alkaline pH at all times. The pH of fresh samples of the AH Plus and ThermaSeal sealers was alkaline at first but decreased significantly after 24 hours. The viscosity of the tested sealers increased with the decreased injection rates. Conclusions The tested sealers were pseudoplastic according to their viscosities as determined in this study. The MTA Fillapex and Endosequence BC sealers each possessed comparable flow and dimensional stability but higher film thickness and solubility than the other sealers tested.
Mathematical models are important methods in estimating epidemiological patterns of diseases and predicting the consequences of the spread of diseases. Investigation of risk factors of transportation ...modes and control of transportation exposures will help prevent disease transmission in the transportation system and protect people’s health. In this paper, a multimodal traffic distribution model is established to estimate the spreading of virus. The analysis is based on the empirical evidence learned from the real transportation network which connects Wuhan with other cities. We consider five mainstream travel modes, namely, auto mode, high-speed railway mode, common railway mode, coach mode, and flight mode. Logit model of economics is used to predict the distribution of trips and the corresponding diseases. The effectiveness of the model is verified with big data of the distribution of COVID-19 virus. We also conduct model-based tests to analyze the role of lockdown on different travel modes. Furthermore, sensitivity analysis is implemented, the results of which assist in policy-making for containing infection transmission through traffic.
H2O molecules in emerald channels have been extensively discussed over the past half century. Recent studies paid attention to their classification and coordination, but have mostly focused on the ...type related to Na+. There are few works on the other types, and the related infrared (IR) absorption bands are rather controversial. This paper investigated natural emeralds from China and Colombia by means of micro-Fourier transform infrared (μ-FTIR) spectroscopy, micro-confocal Raman spectroscopy, and laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). The results suggested that doubly (IId) and singly (IIs) coordinated H2O molecules were incorporated in natural emerald channels. Type IId H2O predominated in those emeralds with relatively low alkali content. As the alkali content increased, the proportion of type IIs H2O rose, stemming from the decrease of the H2OII/Na+ apfu ratio. Moreover, IR bands of H2O corresponding to Li+ and Cs+ were tentatively ascribed here. IR bands for D2O and HDO in Colombian sample were observed in the range of 2600–2850 cm−1 and preliminarily assigned, which might be a potential tool for emerald origin determination. Our work expanded the existing classification of water molecules in emerald channels and redefined the controversial IR absorption bands.
A
bstract
We obtain the complete and independent bases of effective operators at mass dimension 5, 6, 7, 8, 9 in both standard model effective field theory with light sterile right-handed neutrinos (
...ν
SMEFT) and low energy effective field theory with light sterile neutrinos (
ν
LEFT). These theories provide systematical parametrizations on all possible Lorentz-invariant physical effects involving in the Majorana/Dirac neutrinos, with/without the lepton number violations. In the
ν
SMEFT, we find that there are 2 (18), 29 (1614), 80 (4206), 323 (20400), 1358 (243944) independent operators with sterile neutrinos included at the dimension 5, 6, 7, 8, 9 for one (three) generation of fermions, while 24, 5223, 3966, 25425, 789426 independent operators in the
ν
LEFT for two generations of up-type quarks and three generations of all other fermions.
Bioelectronics for modulating the nervous system have shown promise in treating neurological diseases
. However, their fixed dimensions cannot accommodate rapid tissue growth
and may impair ...development
. For infants, children and adolescents, once implanted devices are outgrown, additional surgeries are often needed for device replacement, leading to repeated interventions and complications
. Here, we address this limitation with morphing electronics, which adapt to in vivo nerve tissue growth with minimal mechanical constraint. We design and fabricate multilayered morphing electronics, consisting of viscoplastic electrodes and a strain sensor that eliminate the stress at the interface between the electronics and growing tissue. The ability of morphing electronics to self-heal during implantation surgery allows a reconfigurable and seamless neural interface. During the fastest growth period in rats, morphing electronics caused minimal damage to the rat nerve, which grows 2.4-fold in diameter, and allowed chronic electrical stimulation and monitoring for 2 months without disruption of functional behavior. Morphing electronics offers a path toward growth-adaptive pediatric electronic medicine.
Activity detection and classification are very important for autonomous monitoring of humans for applications, including assistive living, rehabilitation, and surveillance. Wearable sensors have ...found wide-spread use in recent years due to their ever-decreasing cost, ease of deployment and use, and ability to provide continuous monitoring as opposed to sensors installed at fixed locations. Since many smart phones are now equipped with a variety of sensors, such as accelerometer, gyroscope, and camera, it has become more feasible to develop activity monitoring algorithms employing one or more of these sensors with increased accessibility. We provide a complete and comprehensive survey on activity classification with wearable sensors, covering a variety of sensing modalities, including accelerometer, gyroscope, pressure sensors, and camera- and depth-based systems. We discuss differences in activity types tackled by this breadth of sensing modalities. For example, accelerometer, gyroscope, and magnetometer systems have a history of addressing whole body motion or global type activities, whereas camera systems provide the context necessary to classify local interactions, or interactions of individuals with objects. We also found that these single sensing modalities laid the foundation for hybrid works that tackle a mix of global and local interaction-type activities. In addition to the type of sensors and type of activities classified, we provide details on each wearable system that include on-body sensor location, employed learning approach, and extent of experimental setup. We further discuss where the processing is performed, i.e., local versus remote processing, for different systems. This is one of the first surveys to provide such breadth of coverage across different wearable sensor systems for activity classification.
Many methods designed to create defenses against distributed denial of service (DDoS) attacks are focused on the IP and TCP layers instead of the high layer. They are not suitable for handling the ...new type of attack which is based on the application layer. In this paper, we introduce a new scheme to achieve early attack detection and filtering for the application-layer-based DDoS attack. An extended hidden semi-Markov model is proposed to describe the browsing behaviors of web surfers. In order to reduce the computational amount introduced by the model's large state space, a novel forward algorithm is derived for the online implementation of the model based on the M-algorithm. Entropy of the user's HTTP request sequence fitting to the model is used as a criterion to measure the user's normality. Finally, experiments are conducted to validate our model and algorithm.
Described herein is a manganese‐catalyzed dehydrogenative 4+2 annulation of NH imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation ...represents the first example of manganese‐catalyzed CH activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed CH activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle.
Hidden talents: The ability of manganese(I) to catalytically induce CH and NH bond cleavage, and CC and CN bond formation, has been recognized using the title reaction. The reaction produces H2 as the major by‐product and eliminates the need for any oxidants, external ligands, or additives, and thus tolerating a wide range of functionalities.
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