A noteworthy frame of the literature has maintained the idea that communication in the classroom is dominant in language education, and in the process of language learning, teachers as an important ...figure may apply several ways to develop interpersonal relationships and social manners, such as teacher immediacy that has been established to support affective and cognitive learning in instructional settings. Therefore, this theoretical review tries to systematically refocus on the existing literature about teacher immediacy and its types, such as non-verbal and verbal, and their significant connections with affective and cognitive education. To this end, this review focuses on social behavior to review the eminence of teacher immediacy in the classroom and unquestionably exemplify their relationship with affective and cognitive learning. As a final fact, this review has been intended to consider the prevailing literature about teacher behavior, and suggestions and recommendations have been presented correspondingly for language teaching stakeholders in the educational setting.
Plasmonic colorimetric sensors have emerged as a powerful tool in chemical and biological sensing applications due to the localized surface plasmon resonance (LSPR) extinction in the visible range. ...Among the plasmonic sensors, the most famous sensing mode is the “aggregation” plasmonic colorimetric sensor which is based on plasmon coupling due to nanoparticle aggregation. Herein, this review focuses on the newly-developing plasmonic colorimetric sensing mode – the etching or the growth of metal nanoparticles induces plasmon changes, namely, “non-aggregation” plasmonic colorimetric sensor. This type of sensors has attracted increasing interest because of their exciting properties of high sensitivity, multi-color changes, and applicability to make a test strip. Of particular interest, the test strip by immobilization of nanoparticles on the substrate can avoid the influence of nanoparticle auto-aggregation and increase the simplicity in storage and use. Although there are many excellent reviews available that describe the advance of plasmonic sensors, limited attention has been paid to the plasmonic colorimetric sensors based on etching or growth of metal nanoparticles. This review highlights recent progress on strategies and application of “non-aggregation” plasmonic colorimetric sensors. We also provide some personal insights into current challenges associated with “non-aggregation” plasmonic colorimetric sensors and propose future research directions.
Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles. Display omitted
•The strategies for plasmonic colorimetric sensors based on nanoparticles etching/growth are reviewed.•Highlighted applications in environmental as well as biological analysis are provided.•The advantages and future directions of this kind of sensing platforms are detailed discussed.
Molecular imprinting-based solid-phase extraction (MI-SPE) has been in the spotlight to improve the recognition selectivity and detection sensitivity. MI-SPE provides a powerful tool for ...chemo/bioanalysis in complex matrices and meanwhile, benefits from distinguished advantages such as easy operation, high throughput, low cost, high selectivity and durability. This review proposed the recent advances in molecular imprinting concerning novel preparation strategies of molecularly imprinted polymers (MIPs) and typical applications of MI-SPE. Preparation strategies are highlighted by dividing into ten sections mainly including dummy imprinting, multi-template imprinting, surface imprinting, water-compatible imprinting, restricted access material combining imprinting etc.; each section provides the descriptions about what restrictions led to the emergence of any strategy, strengths/weaknesses of every strategy and universal applications of upgraded MIPs in various SPE modes prior to chromatographic analysis. The potential of MIPs for implementation in routine laboratory activities and scale-up is expected, and finally remaining challenges and future perspectives are proposed.
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•Current challenges on MIPs and related imprinting strategies are comprehensively summarized.•Applications of upgraded molecular imprinting based solid-phase extraction are discussed.•The potential of MIPs for implementation in routine laboratory activities and scale-up is summarized.•The future study requirements are highlighted.
Spatial-seasonal variations, sources and correlations with seawater physiochemical factors and the pollution indexes of dissolved heavy metals in the surface seawater of the Yellow River Estuary in ...China were investigated. The concentrations of copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), arsenic (As) and mercury (Hg) had ranges of 0.04–31.0 (11.6 ± 7.08), 0.42–13.3 (5.61 ± 3.55), 1.97–42.2 (14.9 ± 12.0), 0.10–1.90 (0.66 ± 0.37), 0.16–5.89 (2.59 ± 1.12) and 0.10–0.52 μg/L (0.24 ± 0.07), respectively, throughout the four seasons of the year. The concentrations of Cu, Pb, Zn and Cd were significantly high in winter relative to those in the other seasons, and the highest concentrations of Zn and Hg were detected in spring. The single contaminator factors of the elements are in the following order: Pb > Hg > Cu > Zn > Cd > As. The obtained degree of contamination showed that the Yellow River Estuary was highly polluted. The Cu and Zn concentrations were significantly correlated with temperature and suspended particulate matter (SPM). The Cd concentrations were significantly correlated with temperature, SPM, chemical oxygen demand (COD) and dissolved oxygen (DO). The As concentrations were significantly correlated with temperature, salinity, SPM and DO. The Hg concentrations were significantly correlated with salinity. We performed hierarchical cluster and principal component analyses to investigate the possible sources of heavy metals. Agricultural, industrial and atmospheric deposition resources were found to be possible sources of dissolved heavy metals in the studied area. Longshore currents, upwelling and the physicochemical parameters were possible influence factors of dissolved heavy metals spatial and seasonal distribution.
•Spatial-seasonal variations of heavy metals in the Yellow River Estuary were studied.•The obtained degree of contamination showed that the Yellow River Estuary was highly polluted.•Multiple pollution sources were found.•Longshore currents, upwelling and the physicochemical parameters were possible influence factors of dissolved heavy metals spatial and seasonal distribution.
One pressing concern today is to construct sensors that can withstand various disturbances for highly selective and sensitive detecting trace analytes in complicated samples. Molecularly imprinted ...polymers (MIPs) with tailor-made binding sites are preferred to be recognition elements in sensors for effective targets detection, and fluorescence measurement assists in highly sensitive detection and user-friendly control. Accordingly, molecular imprinting-based fluorescence sensors (MI-FL sensors) have attracted great research interest in many fields such as chemical and biological analysis. Herein, we comprehensively review the recent advances in MI-FL sensors construction and applications, giving insights on sensing principles and signal transduction mechanisms, focusing on general construction strategies for intrinsically fluorescent or nonfluorescent analytes and improvement strategies in sensing performance, particularly in sensitivity. Construction strategies are well overviewed, mainly including the traditional indirect methods of competitive binding against pre-bound fluorescent indicators, employment of fluorescent functional monomers and embedding of fluorescence substances, and novel rational designs of hierarchical architecture (core-shell/hollow and mesoporous structures), post-imprinting modification, and ratiometric fluorescence detection. Furthermore, MI-FL sensor based microdevices are discussed, involving micromotors, test strips and microfluidics, which are more portable for rapid point-of-care detection and in-field diagnosing. Finally, the current challenges and future perspectives of MI-FL sensors are proposed.
•Molecular imprinting based fluorescence sensors (MI-FL sensors) are reviewed.•Sensing principle and signal transduction mechanisms are introduced.•General and novel construction strategies for MI-FL sensors are summarized.•MI-FL sensor based microdevices are overviewed.•The present challenges and perspectives of MI-FL sensors are proposed.
Separating point clouds into ground and non-ground measurements is an essential step to generate digital terrain models (DTMs) from airborne LiDAR (light detection and ranging) data. However, most ...filtering algorithms need to carefully set up a number of complicated parameters to achieve high accuracy. In this paper, we present a new filtering method which only needs a few easy-to-set integer and Boolean parameters. Within the proposed approach, a LiDAR point cloud is inverted, and then a rigid cloth is used to cover the inverted surface. By analyzing the interactions between the cloth nodes and the corresponding LiDAR points, the locations of the cloth nodes can be determined to generate an approximation of the ground surface. Finally, the ground points can be extracted from the LiDAR point cloud by comparing the original LiDAR points and the generated surface. Benchmark datasets provided by ISPRS (International Society for Photogrammetry and Remote Sensing) working Group III/3 are used to validate the proposed filtering method, and the experimental results yield an average total error of 4.58%, which is comparable with most of the state-of-the-art filtering algorithms. The proposed easy-to-use filtering method may help the users without much experience to use LiDAR data and related technology in their own applications more easily.
It is still challenging to sensitively detect protein biomarkers via surface-enhanced Raman scattering (SERS) technique owing to their low Raman activity. SERS tag-based immunoassay is usually ...applied; however, it is laborious and needs specific antibodies. Herein, an ultrasensitive and universal “Raman indicator” sensing strategy is proposed for protein biomarkers, with the aid of a glass capillary-based molecularly imprinted SERS sensor. The sensor consists of an inner SERS substrate layer for signal enhancement and an outer mussel-inspired polydopamine imprinted layer as a recognition element. Imprinted cavities have two missions: first, selectively capturing the target protein, and second, the only passageway of Raman indicator to access SERS substrate. Specific protein recognition means filling imprinted cavities and blocking Raman indicator flow. Thus, the quantity of captured protein can be reflected by the signal decrease of ultra-Raman active indicator molecule. The capillary sensor exhibited specific and reproducible detection at the level down to 4.1 × 10−3 μg L−1, for trypsin enzyme in as-received biological samples without sample preparation. The generality of the mechanism is confirmed by using three different protein models. This platform provides a facile, fast and general route for sensitive SERS detection of Raman inactive biomacromolecules, which offers great promising utility for in situ and fast point-of-care practical bioassay.
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•Label-free “Raman indicator” sensing strategy was proposed for biomarker detection.•Commercial glass capillary substrate was used to improve synthesis reproducibility.•MIP-SERS sensor enabled fast biomarker sensing in 50 μL of crude biological samples.•Ultra-low detection limit of 4.1 × 10−3 μg L−1 was obtained for trypsin enzyme.
Abstract
Chiral discrimination is critical in environmental and life sciences. However, an ideal chiral discrimination strategy has not yet been developed because of the inevitable nonspecific ...binding entity of wrong enantiomers or insufficient intrinsic optical activities of chiral molecules. Here, we propose an “inspector” recognition mechanism (IRM), which is implemented on a chiral imprinted polydopamine (PDA) layer coated on surface-enhanced Raman scattering (SERS) tag layer. The IRM works based on the permeability change of the imprinted PDA after the chiral recognition and scrutiny of the permeability by an inspector molecule. Good enantiomer can specifically recognize and fully fill the chiral imprinted cavities, whereas the wrong cannot. Then a linear shape aminothiol molecule, as an inspector of the recognition status is introduced, which can only percolate through the vacant and nonspecifically occupied cavities, inducing the SERS signal to decrease. Accordingly, chirality information exclusively stems from good enantiomer specific binding, while nonspecific recognition of wrong enantiomer is curbed. The IRM benefits from sensitivity and versatility, enabling absolute discrimination of a wide variety of chiral molecules regardless of size, functional groups, polarities, optical activities, Raman scattering, and the number of chiral centers.
In this work, novel dummy molecularly imprinted polymers (DMIP) with propanamide as a dummy template molecule were prepared based on a green synthesis strategy of less consumption of ...hazardous/organic reagents and at mild conditions for magnetic solid-phase extraction (MSPE) of acrylamide in biscuit samples, followed by high performance liquid chromatography (HPLC) determination. The resultant DMIP was well characterized by FT-IR, SEM, TEM and VSM, exhibiting uniform nanoscale coreshell structure and good magnetic property in favor of simple rapid separation. Several main variables influencing MSPE efficiency were investigated, including DMIP dosage, sample solution pH, extraction time and desorption solvent; central composite design (CCD) and response surface methodology (RSM) were employed to assist in the MSPE condition optimization with rapidity and reliability. Under optimized conditions, excellent linearity for acrylamide was obtained in the range of 5.0–5000.0 µg kg−1, and low detection and quantification limits were 1.3 µg kg−1 and 4.4 µg kg−1, respectively. The method recoveries at five spiked concentrations were found within 86.0–98.3% with relative standard deviations (RSDs) of 1.2–4.1%. Furthermore, endogenous acrylamide was detected in five different biscuit samples and the RSDs values were lower than 3.3%. The present study suggested promising perspectives of water-compatible eco-friendly DMIP based MSPE-HPLC method for highly effective sample pretreatment and targeted analytes determination in complicated matrices.
Novel dummy molecularly imprinted polymers were prepared based on a green synthesis strategy for magnetic solid-phase extraction of acrylamide in biscuit samples. Display omitted
•Dummy molecularly imprinted polymers (DMIP) were prepared by a green synthesis strategy.•DMIP based magnetic SPE (MSPE) for acrylamide.•Ice bath was used instead of organic solvent in washing step.•MSPE variables were simply effectively optimized by experimental design.•DMIP-MSPE-HPLC method was applicable to complicated food matrices.
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