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A novel synthesis method for fabricating large area, uniform bulk-heterojunction films with electron donor and acceptor materials homogeneously distributed among each other forming a bicontinuous network morphology is reported.

Background/purpose Sealer residues on dentin may affect bonding to restorative materials. This study aimed to evaluate the bond strength to sealer-contaminated dentin after using different cleaning protocols. Materials and methods Freshly extracted bovine incisors were prepared and exposed the buccal pulp chamber dentin, obtaining segments measuring 5 mm × 5 mm with a height of 3 mm. The segments were randomly distributed into 4 groups (n = 7) according to different protocols. Control group: no contamination was performed. In the three experimental groups, the segments were contaminated with epoxy resin-based sealer for 5 min, and different cleaning protocols were performed. Acetone group: acetone-saturated cotton pellets were used to wipe the sealer. Ultrasound group: ultrasonic ET-20D tip cleaning. Acetone combined with ultrasound group: cleaning with acetone-saturated cotton pellets and ultrasonic tip. All segments were bonded using a self-etch adhesive. Two samples in each group were scanned by swept-source optical coherence tomography (SS-OCT) to evaluate sealer residues. A microtensile test was performed on the remaining 5 samples, which were built up with composite resin. Results Sealer residues were observed in 3 of 14 (21.4%) sections of acetone group by SS-OCT. Compared to the control, ultrasound alone or in combination with acetone preserved the bond strength (P > .05). The ultrasound group exhibited the highest bond strength (39.38 MPa), which differed from that of the acetone group, which provided the lowest bond strength (32.88 MPa) (P Conclusion Cleaning epoxy resin-based sealer-contaminated dentin surfaces using ultrasound or combined with acetone could preserve the bond strength.

Construction of working electrodes relying on active materials for electrochemical chlorophenol sensors.

Restless legs syndrome (RLS) is a common non-motor symptom in Parkinson's disease (PD), but its pathogenesis remains unclear. This study aimed to explore the potential neural substrates of RLS in a large sample of patients with PD.A total of 42 patients with PD with RLS and 124 patients with PD without RLS were prospectively recruited at our hospital between February 2019 and October 2020 and underwent structural and resting-state functional magnetic resonance imaging. Differences between the two patient groups were assessed using voxel-based morphometry and functional connectivity analysis. PD duration, Part III of the Movement Disorder Society's Unified Parkinson's Disease Rating Scale (MDS-UPDRS-III) score, and levodopa equivalent daily dose were treated as covariates.Patients with PD with RLS had significantly larger gray matter volume in the bilateral posterior cingulate cortex than patients with PD without RLS (FDR-adjusted P 0.05). Compared to patients without RLS, those with RLS had significantly lower functional connectivity between the left central opercular cortex and the bilateral precentral gyri and postcentral gyri (FDR-adjusted P 0.001).Our study provides the first evidence that in patients with PD, RLS is associated with significantly larger gray matter volume in the posterior cingulate cortex and lower resting-state functional connectivity within the sensorimotor network. Our results may help clarify the pathophysiology of RLS in PD and identify possible therapeutic targets.

Because of their high hazards and presence in various common scenarios (e.g., workplace, residence, or bio-conversion systems), aldehydes have attracted enormous attention in the research and development of chemical sensors and other detection methods that can provide the quick and sensitive detection of aldehydes, particularly in the gas phase, thus enabling the real-time monitoring of air pollution and impact to health and environment. Among all the detection methods, an optical chemosensor, which relies on aldehyde-triggered color or fluorescence emission change, is typically small in size, easy to operate, and low cost, offering great advantages over benchtop spectrophotometric or chromatographic instrumentation methods, which are large in size and non-portable, complicated to operate, and expensive to maintain. This review will provide a comprehensive overview of the most remarkable development in the gas phase detection of aldehydes (especially the highly volatile aliphatic aldehydes such as formaldehyde and acetaldehyde) in recent years, mostly focusing on the colorimetric, fluorometric, colorimetric/fluorometric dual-mode, and chemiluminescent sensing methods. The review is specifically centered on the discussion of the sensor mechanism in correlation with various molecular designs and materials structural engineering, which, when combined, would lead to maximum sensor performance with respect to both the detection sensitivity and selectivity. At the end of this paper, we also provide the future perspectives concerned with the future development of optical chemosensors and miniaturized device systems, which will be more suited for deployment in practical applications for the quick and onsite detection of aldehydes.

One-dimensional nanostructures are self-assembled from an amphiphilic arylene-ethynylene macrocycle (AEM) in solution phase. The morphology and size of the nanostructures are controlled by simply changing the temperature, reversibly switching between monomolecular cross-sectioned nanofibers and large bundles. At elevated temperature in aqueous solutions, the tri(ethylene glycol) (Tg) side chains of the AEM become effectively more hydrophobic, thus facilitating intermolecular association through side chain interactions. The enhanced intermolecular association causes the ultrathin nanofibers to be bundled, forming an opaque dispersion in solution. The reported observation provides a simple molecular design rule that may be applicable to other macrocycle molecules for use in temperature-controlled assembly regarding both size and morphology.

In this work, we report the fabrication of a two-member fluorescence sensor array that enables the assessment of three stages (fresh, slightly spoiled, and moderately or severely spoiled) of meat spoilage. The first member of the array, which has strong chalcogen bonding and sulfur-π interactions with organic sulfides, exhibits very high sensitivity, while the second member of the array, which has weak chalcogen bonding and sulfur-π interactions with organic sulfides, exhibits lower sensitivity. On the basis of the combined fluorescence responses of the two members, three stages of meat spoilage, including fresh, slightly spoiled, and moderately or severely spoiled, can be monitored. Notably, using the volatiles collected from 5 g of meat products over a short period of time (1 min), this two-member sensor array achieves sensitive responses to the organic sulfides emitted from the meats. The capacity of this method to rapidly assess meat freshness facilitates its practical application, as illustrated by the monitoring of the freshness of chicken and pork products in the real world.

This study aims to develop an engineering solution to breath tests using an electronic nose (e-nose), and evaluate its diagnosis accuracy for silicosis. Influencing factors of this technique were explored. 398 non-silicosis miners and 221 silicosis miners were enrolled in this cross-sectional study. Exhaled breath was analyzed by an array of 16 organic nanofiber sensors along with a customized sample processing system. Principal component analysis was used to visualize the breath data, and classifiers were trained by two improved cost-sensitive ensemble algorithms (random forest and extreme gradient boosting) and two classical algorithms (K-nearest neighbor and support vector machine). All subjects were included to train the screening model, and an early detection model was run with silicosis cases in stage I. Both 5-fold cross-validation and external validation were adopted. Difference in classifiers caused by algorithms and subjects was quantified using a two-factor analysis of variance. The association between personal smoking habits and classification was investigated by the chi-square test. Classifiers of ensemble learning performed well in both screening and early detection model, with an accuracy range of 0.817–0.987. Classical classifiers showed relatively worse performance. Besides, the ensemble algorithm type and silicosis cases inclusion had no significant effect on classification (p > 0.05). There was no connection between personal smoking habits and classification accuracy. Breath tests based on an e-nose consisted of 16× sensor array performed well in silicosis screening and early detection. Raw data input showed a more significant effect on classification compared with the algorithm. Personal smoking habits had little impact on models, supporting the applicability of models in large-scale silicosis screening. The e-nose technique and the breath analysis methods reported are expected to provide a quick and accurate screening for silicosis, and extensible for other diseases.

Perylene imide (PI) molecules and materials have been extensively studied for optical chemical sensors, particularly those based on fluorescence and colorimetric mode, taking advantage of the unique features of PIs such as structure tunability, good thermal, optical and chemical stability, strong electron affinity, strong visible light absorption and high fluorescence quantum yield. PI-based optical chemosensors have now found broad applications in gas phase detection of chemicals, including explosives, biomarkers of some food and diseases (such as organic amines (alkylamines and aromatic amines)), benzene homologs, organic peroxides, phenols and nitroaromatics, etc. In this review, the recent research on PI-based fluorometric and colorimetric sensors, as well as array technology incorporating multiple sensors, is reviewed along with the discussion of potential applications in environment, health and public safety areas. Specifically, we discuss the molecular design and aggregate architecture of PIs in correlation with the corresponding sensor performances (including sensitivity, selectivity, response time, recovery time, reversibility, etc.). We also provide a perspective summary highlighting the great potential for future development of PIs optical chemosensors, especially in the sensor array format that will largely enhance the detection specificity in complexed environments.

Organic materials with redox activities are promising candidates for aqueous flexible sodium ion storage devices (AFSISDs) due to their mechanical flexibility and low dissolution in aqueous electrolytes. However, the advantages of organic electrodes are not fully exploited due to uncontrollable morphologies with sluggish electrochemical kinetics, and lack of deep understanding about the storage mechanism via in situ technologies. Herein, an interfacial self-assembly strategy is proposed to directly construct PTCDI nanofibers onto flexible ITO substrates by a binder-free approach. Combining in situ Raman spectroscopy and DFT calculations, the Na+ storage mechanism based on an enolization reaction (–CO ↔ –C–O–Na) of two carbonyl groups located in the para position of PTCDI is illuminated. Coupled with an activated carbon cathode, the organic AFSISD delivers an ultrahigh energy density of 83.8 W h kg−1 and a largely improved power density of 3.4 kW kg−1. The as-prepared organic nanofibers show a superior volumetric energy and high power density (i.e., 7.1 mW h cm−3 and 289.7 mW cm−3). This work opens up new horizons for a wide variety of flexible electronics based on organic electrode materials in aqueous neutral electrolytes.

This paper aims to validate the feasibility of hairwork dyeing effluent (HDE) reclamation using an ultrafiltration (UF)-reverse osmosis (RO) integrated membrane system combined with coagulation-flocculation and sedimentation acquiring the highest possible product water recovery rate along with both satisfactory separation performance and well controlled membrane fouling. Under the circumstance of only physical cleaning involved, the laboratory-scale test yielded a higher and satisfactory reuse ratio of 76% for HDE, and the corresponding RO product as reclaimed water contained only 223 mg·L−1 of TDS, 3.87 mg·mL−1 of DOC and 10.3 mg·mL−1 of total hardness, which was obviously better than the quality of existing feedwater in hairwork dyeing process. After each processing unit, the distributions of fulvic (region III) and humic (region V) organics decreased continuously, while an overall rising trend in distribution of protein-like organics (regions I and II) was observed. Contact angle for the fouled UF and RO membranes significantly increased by 19.5° and decreased by 19.7°, respectively, which suggested that different polarity of organic or inorganic adsorption rather than membrane roughness was the main factors affecting wetting properties of the fouled employed membranes. Both ATR-FTIR and XPS spectra indicated that organic fouling on UF membrane surface under harsh condition (RUF = 90%) was mild and tolerable, whereas a surprising amount of hydrophilic micromolecular organics riched in carboxyl and hydroxyl functional groups were absorbed on RO membrane surface after permeation.

Stereoregular fused thiophenes (SFTs: especially thieno[3,2-b]thiophene (TT) and dithieo[3,2-b:2′,3′-d]thiophene (DTT)), as stable conjugated structures deriving from thiophene ring enlarge...

The electrochemical behavior of organic conjugated semiconductors and their bulk materials is a considerable and irreplaceable parameter to maintain their diverse electronic or optoelectronic applications. In this paper, a series of n-type symmetrical perylene diimide derivatives (PTCDIs) with substituents (3,4-ethylenedioxythiophene (EDOT), cyclohexane, acetic acid, or propionic acid) at located the nitrogens imide position were synthesized, and their solubility, optical features, thermal stability, as well as solution-phase interfacial self-assembly into one-dimensional (1D) nanofibers and related morphology were discussed in detail. Moreover, a simple but effective method, in situ deposition following in situ self-assembly, was developed to construct uniform electrodes over a large area coated with networked PTCDI nanofibers. Then the electrochemical properties of the PTCDI nanofibers were researched in comparison with their molecules. The excellent variability at molecular or nanoscale morphological level will provide an interesting insight into the research of PTCDIs in a wide range applications of organic electronics.

This paper reports the development of a high-sensitivity gas sensor and the demonstration of selectively detecting green leaf volatiles (GLV, here hexanal) released from damaged plant leaves. The developed sensor is a conductivity sensor that utilized a 5.2-nm gap as the key detection site between electrodes. The gap was coated with with customized molecular probes toward binding to hexanal. The fabricated sensor demonstrated the detection of a GLV, hexanal, from the collected gas samples from damaged plant leaves, sorghum. Gas samples were collected into a tedlar bag from a glass jar containing damaged sorghum leaves. When exposed to hexanal concentrations from 77.7 to 5181.3 ppm, it produced output signal changes in resistance by 1.64~4.45 times. The sensor response time was measured as 41.6 min at a hexanal concentration of 77.7 ppm.

Chemiresistive sensors, particularly those based on nanostructures, have drawn increasing attention for application in security and environmental monitoring, healthcare, biomedicine and others due to their high selectivity and sensitivity in detection of gaseous chemicals. Nanofibers possess large surface area, and exhibit unique electronic and optical properties that arise from their one-dimensional (1D) structures. They are an ideal candidate for development as sensors, even when constructed into heterojunction structures between n-type (electron acceptor) and p-type (electron donor) materials. Nanofibril heterojunctions created are highly tunable for enhancing the interfacial charge separation and transfer by modifying and optimizing both the material electronic structures and interface configuration spacing. This review aims to provide a comprehensive overview of the current state of the art of chemiresistive gas sensors based on nanofibril heterojunctions, with special focus on the control of interfacial charge transfer which is critical to the sensor performances. Various nanofibril heterojunction structures, including inorganic metal oxides, carbon materials, conjugated organic molecules, and functional polymers, are summarized. The properties of precisely tunable interfaces are discussed, in conjunction with the sensor mechanisms. The potential limitations and challenges of these exciting materials and heterojunction structures for further sensor enhancement and real-world application are also discussed. Lastly, an outlook is given on the future directions of developing nanofibril heterojunction sensors. This review will not only provide deep understanding of the structural design of nanofibril heterojunctions, and the interfacial charge transfer and chemiresistive sensor mechanisms, but also lay out more potential for extending them to other electronic and optoelectronic applications.

Incorporation of visible light active semiconductors without doping noble (transition) metals results in remarkably different construction principle of visible light driven photocatalysts in which light absorptions and charge transfer become more flexible and efficiencies are no longer limited in ultraviolet (UV) region. Herein, we provide a strategy to design efficient photocatalysts by introducing visible light sensitive Ce2O3 into UV active TiO2 via molten salt synthesis (MSS) of CeTiO4 for visible light CO2 reduction. By changing salt composition in the MSS process, the nanostructured CeTiO4 was prepared and exhibited distinct morphologies e.g., nanorods (NaCl NaH2PO4), polyhedrons (KCl NaCl) and cubic (KCl Na2SO4), respectively. Of the different morphologies, the nanorods of CeTiO4 showed best photoactiviy with quantum efficiencies of 0.36% and 0.065% for CO and CH4 formation, respectively. The unique morphologies well positioned band edges cause such obvious differences and co-contribute to the high performance effectiveness. This study demonstrates a strategy for the rational design and fabrication of visible light driven photocatalysts with controlled morphology, which in turn, can enhance the control and production of value-added products of CO2 reduction. This is an important step towards realizing the utilization of renewable energy sources, such as solar power, to reduce the concentration of atmospheric CO2 and form green energy sources.

Two twisted donor–acceptor cruciform luminophores (DHCS-TPE and DMCS-TPE) that were composed of two π-conjugated segments connected via a central benzene core have been prepared. Such cruciforms showed unique intramolecular charge transfer (ICT) emission, obvious aggregation-induced emission (AIE) properties (αAIE = 19 and 20, respectively) and high solid state efficiency (0.913 and 0.424, respectively). Especially, the two compounds exhibited substituent-dependent mechanofluorochromic (MFC) behavior. The as-prepared powders of the more twisted DMCS-TPE could emit strong blue-green light centered at 474 nm, and the fluorescence color changed into yellowish green (531 nm) after grinding, a red shift of 57 nm was observed. Such mechanochromism was reversible upon the treatment of grinding and fuming with DCM. The high contrast MFC behavior of DMCS-TPE originated from the planarization of the molecular conformation and subsequent planar intramolecular charge transfer (PICT) under external force. By sharp contrast, the less twisted DHCS-TPE exhibited no MFC behavior. The reason is that the less twisted molecular conformation of DHCS-TPE generates strong intermolecular forces and close packing. Thus compared to DMCS-TPE, the crystalline solid powders of DHCS-TPE possess higher lattice energy and better structural stability. The grinding of the crystalline solid powders of DHCS-TPE cannot lead to amorphization and mechanochromic luminescence.