Search

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.

The precise control and monitoring of pH values remain critical for many chemical, physiological and biological processes. Perylene diimide (PDI)-based molecules and materials exhibit excellent thermal, chemical and photochemical stability, unique UV-vis absorption and fluorescent emission properties, low cytotoxicity, as well as intrinsic electron-withdrawing (n-type semiconductor) nature and impressive molecular assembly capability. These features combined enable promising applications of PDIs in chemosensors via optical signal modulations (e.g., fluorescent or colorimetric). One of the typical applications lies in the probing of pH under various conditions, which in turn helps monitor the extracellular (environmental) and intracellular pH change and pH-relying molecular recognition of inorganic or organic ions, as well as biological species, and so on. In this review, we give a special overview of the recent progress in PDI-based optical chemosensors for pH probing in various aqueous and binary water–organic media. Specific emphasis will be given to the key design roles of sensing materials regarding the architectures and the corresponding sensing mechanisms for a sensitive and selective pH response. The molecular design of PDIs and structural optimization of their assemblies in order to be suitable for sensing various pH ranges as applied in diverse scenarios will be discussed in detail. Moreover, the future perspective will be discussed, focusing on the current key challenges of PDI-based chemosensors in pH monitoring and the potential approach of new research, which may help address the challenges.

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.

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.

Surface-induced crystallization of an isotropic Bi nanodroplet in three distinct steps was recorded at atomic resolution by in situ high resolution transmission electron microscopy. First, formation of a crystalline nucleus at the edge of the nanodroplet is induced by the liquid-state surface faceting, which initiates the formation of a prefreezing state with a distorted structure. Then, a periodic line pattern of the atomic columns with a periodicity of 0.49 nm that is relative to the interlayer spacing of the Bi crystal along the ⟨112⟩* direction (one-dimensional ordered structure) was formed by structure relaxation of the prefreezing nanoparticle, followed by a concerted growth and ordering process. Finally, the crystallization from the periodic structure was carried out by atom/atom interactions within and between the atomic layers to form the covalent Bi–Bi bonds that have the same arrangement as in the Bi crystal (crystallization along the ⟨110⟩ direction). Motivated by the experimental observation...

Background High level of red blood cell distribution width (RDW) has been associated with adverse outcomes in coronary artery disease patients. We aimed to investigate the relationship between RDW and the risk of myocardial injury in chest pain patients. Methods and Results We retrospectively reviewed 2078 chest pain patients with suspected acute myocardial infarction. Myocardial injury was defined as high-sensitivity cardiac troponin T (hs-cTnT) >14 ng/L. RDW was associated with hs-cTnT (r = 0.607) and the risk of myocardial injury stepwise increased across increasing RDW quartiles in all subgroups based on age and sex. The receiver operating characteristic curve analysis was calculated to assess the elevated RDW to predict myocardial injury, with the cutoff value of 13.25%. RDW had a high sensitivity (78.10%), specificity (87.44%), as well as positive predictive value (77.48%). The area under the curve (AUC) for all patients was 0.88 (95%CI 0.87, 0.90) and there is no statistical significant in AUCs for all subgroups. Conclusions Elevated RDW was significantly associated with a higher risk of myocardial injury in chest pain patients with potential acute myocardial infarction. The RDW may be helpful to identify myocardial injury in such patients.

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively studied for one-dimensional (1D) self-assembled systems and for applications in photocatalysis. Herein, we constructed a PTCDI-based donor-acceptor (D-A) supramolecular system via in situ self-assembly on an indium tin oxide conductive glass surface. The self-assembled PTCDI nanostructures exhibit well-defined nanofibril morphologies and strong photocurrents. Interestingly, a strong and reversible electrochromic color change was observed during cyclic voltammetry. The color of the nanofibers changed from red to blue and then to violet as the reduction progressed to the radical anion and then to the dianion. This series of one-electron reductions was confirmed by UV absorption, electron paramagnetic resonance spectroscopy, and hydrazine reduction. Most importantly, these PTCDI nanofibers exhibit efficient photoelectrocatalytic hydrogen production with remarkable stability under xenon lamp illumination (λ ≥ 420 nm). Among the three nanofibers prepared, the fibers assembled from PTCDI molecule 2 were found to be the most effective catalyst with 30% Faradaic efficiency. In addition, the nanofibers produced hydrogen at a steady-state for more than 8 h and produced repeatable results in 3 consecutive testing cycles, giving them great potential for practical industrial applications. Under an applied bias voltage, the 1D intermolecular stacking along the long axis of the nanofibers affords efficient separation and migration of photogenerated charge carriers, which play a crucial role in the photoelectrocatalytic process. As a proof-of-concept, the D-A-structured PTCDI nanofibers presented herein may guide future research on photoelectrocatalysis based on self-assembled supramolecular systems by providing more options for material design of the catalysts to achieve greater efficiencies.

A highly sensitive and selective carbon nanotube-based vapor sensor was developed toward the detection of methamphetamine vapor, one of the most widespread, harmful and addictive illegal drugs in the world. Poly[3-(6-carboxyhexyl)thiophene-2,5-diyl)] (P3CT) was chosen to non-covalently functionalize carbon nanotubes, which can facilitate the suspension of carbon nanotubes in the solvents as well as introduce a carboxylic acid functional group. The carboxylic acid group in the polymer acts as a binder of organic amines via acid-base interaction. The P3CT-functionalized carbon nanotube sensors show sensitivity to n -methylphenethylamine (NMPEA), a detection simulant of methamphetamine, as low as 4 ppb. The sensors were able to distinguish NMPEA from two other amine compounds, various volatile chemical compounds (VOCs), and water vapor by observing the recoverability of the sensor’s signal after exposure. The sensor showed higher sensitivity to amine vapors even when the vapor concentrations of amines were several orders of magnitude lower than those of the VOCs. Our research gives a simple but effective method for detecting trace amounts of methamphetamine in ambient air. Meanwhile, the sensor developed in this study can be used as one component in a next generation portable, intelligent, and low-cost chemical sensor array system for more complex real-life applications.

Three donor–acceptor (D–A)-containing cruciform luminophores, named DHCS-BC, DMCS-BC, and DTCS-BC, with twisted molecular conformation have been synthesized. The D–A-type cross-conjugated compounds...

We report on a novel colorimetric sensor system for highly sensitive detection of formaldehyde (FA) in the gas phase. The sensor is constructed with paper towel as a substrate coated with the sulfuric acid salt of hydroxylamine ((NH2OH)2·H2SO4) together with two pH indicators, bromophenol blue and thymol blue. Upon exposure to FA, the hydroxylamine will react with the absorbed FA to form a Schiff base (H2C=N-OH), thus releasing a stoichiometric amount of sulfuric acid, which in turn induces a color change of the pH indicator. Such a color change was significantly enriched by incorporating two pH indicators in the system. With the optimized molar ratio of the two pH indicators, the color change (from brown to yellow, and to red) could become so dramatic as to be visible to the eye depending on the concentration of FA. In particular, under 80 ppb of FA (the air quality threshold set by WHO) the color of the sensor substrate changes from brown to yellow, which can even be envisioned clearly by the naked eyes. By using a color reader, the observed color change can be measured quantitatively as a function of the vapor concentration of FA, which produces a linear relationship as fitted with the data points. This helps estimate the limit of detection (LOD), to be 10 ppb under an exposure time of 10 min, which is much lower than the air quality threshold set by WHO. The reported sensor also demonstrates high selectivity towards FA with no color change observed when exposed to other common chemicals, including solvents and volatile organic compounds. With its high sensitivity and selectivity, the proposed paper-based colorimetric sensor thus developed can potentially be employed as a low-cost and disposable detection kit that may find broad application in detecting FA in indoor air and many other environments.

Catalytic hydrogen reduction has appeared as a promising strategy for chemical denitrification with advantages of high activity and simple operation. However, the risk and low utilization of H2 is the disadvantage of catalytic hydrogen reduction. In recent years, catalytic reduction reactions in the presence of sodium borohydride (NaBH4) have been extensively studied. NaBH4 can be used as an electron source to generate electrons on the surface of the catalyst and can catalyze the reduction of pollutants. But it makes commercialization costly and causes significant environmental pollution if widely use NaBH4. In this study, we prepared supported Pd/Sn bimetallic nanoparticles which could adsorb NaBH4 during the preparation of the Pd/Sn bimetallic catalyst as the prestoring reductant. No additional reducing agent is required during nitrate reduction process. The performance and mechanism for nitrate reduction by using Pd/Sn bimetallic nanoparticles were discussed. Moreover, the catalyst D-Pd1/Sn1 reached a complete nitrate removal in the municipal wastewater treatment plant effluent water within 3 h. The results provide a prospect for denitrification in biological wastewater treatment plants.

Photocatalytic oxidation has recently been recognized as an attractive technology for NO removal, in which the main products are NO 2 or HNO 3 . However, these products may cause secondary pollution and deactivation of the involved photocatalysts. In this study, we demonstrate that carbon vacancy-modified nanosheet structure g-C 3 N 4 (Ns-g-C 3 N 4 ) can efficiently and selectively reduce NO to N 2 under visible light. Since N 2 is a green gas and can easily desorb from the active sites, the problems such as secondary pollution and catalyst deactivation are largely avoided. It was found that two structural characters of Ns-g-C 3 N 4 , ultrathin nanostructure and abundant surface defect sites, could promote its visible light absorption, and favor the separation and transfer of photogenerated charge carriers as well as strong chemisorption of NO, leading to high photoreactivity. Meanwhile, the surface defects of Ns-g-C 3 N 4 shift the adsorption structure of NO from C N O for the bulk counterpart to Cv O N (adsorbed at the carbon vacancy site, Cv), eventually resulting in its high selectivity of converting NO to N 2 . The present study underlines the impetus of utilizing surface defect structure to regulate photocatalytic reaction pathway.

In recent years, there has been a wide research in supported single-atom catalysts (SACs), which contain only isolated individual metal atoms dispersed on an appropriate support or coordinated with the surface atoms of the support. The SACs exhibit many fascinating characteristics including high activity, selectivity, and maximum atomic utilization. These characteristics arise from the low coordination status, quantum size effect, and the strong metal–support interaction, which have proved to be very powerful in many typical heterogeneous catalysis field including oxidation, hydrogenation, the water–gas shift reaction, methanol steam reforming, electrocatalysis, and photocatalysis. In this review, we summarized the recent progress in synthesis, characterizations, properties, and applications of SACs.

In general, alkane vapors are difficult to detect due to their non-reactive nature at room temperature. Here, we show chemiresistive sensors made of carbon nanotubes (CNTs) noncovalently functionalized with three kinds of poly(3-alkylthiophene) (P3AT), namely, poly(3-butylthiophene) (P3BT), poly(3-octylthiophene-2,5-diyl) (P3OT) and poly(3-dodecylthiophene-2,5-diyl) (P3DT). We compared the responses of sensors composed of these materials to four linear alkanes, hexane, octane, decane and dodecane. The results show that sensors with CNTs functionalized with P3ATs that have alkyl side chains with length similar to the length of the analyte alkane produced a bigger response than the case in which the lengths are different. Based on this response trend, a sensor array was made, which can distinguish different sizes of linear alkane vapors. This work facilitates the future design of CNT-based sensor arrays for distinguishing analytes with similar physical and chemical properties.

During the detection of industrial toxic gases, such as triethylamine (TEA), poor selectivity and negative humidity impact are still challenging issues. A frequently reported strategy is to employ molecular sieves or metal-organic framework (MOF) membranes so that interference derived from surrounding gases or water vapor can be blocked. Nevertheless, the decline in the response signal was also observed after coating these membranes. Herein, an alternative strategy that is based on a hydrophobic, TEA adsorption-selective p-n conjunction core-shell heterostructure is proposed and is speculated to simultaneously enhance selectivity, sensitivity, and humidity resistance. To verify the practicability of the proposed strategy, a thickness-tunable nitrogen-doped carbon (N-C) shell-coated α-Fe2O3 nano-olive (N-C@α-Fe2O3 NO)-based core-shell heterostructure that is obtained via a unique all-vapor-phase processing method is selected as the research example. After forming the core-shell heterostructure, a relatively hydrophobic and TEA adsorption-selective N-C@α-Fe2O3 NO surface was experimentally confirmed. Particularly, a chemiresistive sensor that comprises N-C@α-Fe2O3 NOs exhibits satisfactory selectivity and response magnitude to TEA when compared with the sensor using α-Fe2O3 NOs. The detection limit can even reduce to be 400 ppb at 250 °C. Furthermore, the sensor based on N-C@α-Fe2O3 NOs shows desirable humidity resistance within the relative humidity (RH) range of 30-90%. For practical usage, a sensing prototype based on the N-C@α-Fe2O3 NO probe is fabricated, and its satisfactory sensing performance further confirms the potential for future applications in industrial organic amine detection. These promising results show a bright future in enhancing the humidity resistance and selectivity as well as sensitivity of chemiresistive sensors by simply designing a hydrophobic and target gas adsorption (e.g., TEA) preferred p-n junction core-shell heterostructure.

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility. In this review, we present a comprehensive overview of the recent research progress of PEDOT:PSS and its composites, and the application in electrochemical and electronic sensors for detecting liquid-phase or gaseous chemical analytes, including inorganic or organic ions, pH, humidity, hydrogen peroxide (H2O2), ammonia (NH3), CO, CO2, NO2, and organic solvent vapors like methanol, acetone, etc. We will discuss in detail the structural, architectural and morphological optimization of PEDOT:PSS and its composites with other additives, as well as the fabrication technology of diverse sensor systems in response to a wide range of analytes in varying environments. At the end of the review will be given a perspective summary covering both the key challenges and potential solutions in the future research of PEDOT:PSS-based chemosensors, especially those in a flexible or wearable format.

Nanostructured conducting polymers (NCPs) have been extensively studied in various organic electronic fields because of their unique, excellent structural, mechanical, electric and photoelectric properties at the nanoscale. The sizes and morphologies of NCPs, which are highly dependent on the original molecular structure and synthesis optimization, play critical roles in the applications involving NCP materials. As a promising strategy among the chemical oxidative polymerization methods, interfacial polymerization (IP) has been used in creation of abundant NCP materials through facilely controlled interfacial oxidative reactions. Here, we present a special review on the research progress of tunable IP involving different interfaces (liquid-liquid, liquid-solid, vapor-solid and vapor-liquid), wherein the precursor monomers can be positioned in either of the two phases. Such highly tunable interfacial fabrication has been proven an effective method for making NCPs and their composites both with controllable structure and properties. The nanostructured materials fabricated therefrom have found broad, increasing applications in supercapacitor, sensor, corrosion protection and other fields as discussed as well in this review. Also given at the end of this review are a summary and prospective overview about the current research issues and future development. It is expected that this review will provide systematic assistance and inspire new ideas for the development of interfacial processing technique in the field of nanostructured polymers.

Keggin-type polyoxometalate (POM), phosphotungstic acid (H3PW12O40), was encapsulated by an oppositely charged COOH-functionalized surface active ionic liquid (SAIL), N-decyl-N′-carboxymethyl imidazolium bromide ([N-C10, N′-COOH-Im]Br), with the assistance of an ionic self-assembly (ISA) process in an aqueous environment. The as-prepared POM/SAIL material possesses multiple active properties, including reversible pH-response and renewable catalyst for dye degradation. Specifically, the POM-based hybrid materials show a great enhancement in catalytic efficiency when it is employed in degradation of methyl orange (MO) in aqueous solution. Furthermore, the electrostatic repulsions between POM and the deprotonated SAIL may result in the pH-induced disassembly and assembly of the hybrid nanomaterials, which provides an expedient method to regenerate the catalytic activity. Therefore, the presented POM/SAIL hybrid materials are expected to improve the common poisoning issue of the traditional heterogeneous cata...

The research on donor–acceptor (D–A) cocrystalline structures based on organic semiconductive molecules has drawn great attention due to their unique optical and electronic properties. Among the building block molecules, derivatives of perylene-3,4,9,10-tetracarboxylic-3,4,9,10-diimides (PTCDI) are of particular interest as these molecules form high performance n-type semiconductors with strong air stability. However, the cocrystal of PTCDIs remains challenging to fabricate, and only few D–A cocrystals of PTCDIs have been reported. Herein, we report a successful molecular self-assembly design for the PTCDI cocrystal with a donor molecule, coronene. Within the triclinic cell of the cocrystal, the PTCDI and coronene molecules achieved 1 : 1 alternated π–π stacking. The cocrystal showed clear red-shifted absorption and photoluminescence bands, implying the strong charge transfer interaction between coronene and PTCDI. Additionally, the cofacial π–π stacking between coronene and PTCDI planes favors strong one-dimensional self-assembly, leading to the formation of microsized fibril cocrystals and arrays. This presented cocrystal design strategy helps to explore new D–A cocrystalline structures, particularly with one-dimensional morphology control.

Effective control of ligand exchange is important in the emerging field of nanoparticle-based meta-materials; controlling both the separation and electronic coupling between nanoparticles impacts the electrical, optical, chemical, and thermal properties of these materials. However, methods to evaluate exchange efficiency are generally lacking for solid state devices. In this paper, it is shown that controlling the initial ligand length determines the efficiency of the secondary ligand's substitution into the nanoparticle array. Controlling this ligand exchange efficiency determines the post-exchange conductance in a manner akin to doping in conventional semiconductor systems. For a series of initial ligand lengths the distribution of nanoparticle separations in the array is determined, and the ligand exchange efficiency is extracted using a bond percolation model. Finally, Monte Carlo simulations of charge transport in the arrays agree with the experimental conductance data for each molecular state and support the determination of the corresponding exchange efficiencies. This analysis provides a general framework for maximizing the efficiency of ligand exchange that will benefit the use of nanoparticle films in electronic, optoelectronic, plasmonic, and sensing systems.

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively investigated for one-dimensional (1D) self-assembly and their applications in optoelectronic devices. Our study on self-assembled PTCDI nanofiber materials revealed a persistent photoconductivity (PPC) effect, which is sustained conductivity after illumination is terminated. A comprehensive understanding of the PPC effect in PTCDI nanofibril materials will enable us to explore and enhance their optoelectronic applications. Here, we have investigated the PPC effect in the nanofibers assembled from 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI) with respect to the PPC relaxation at different temperatures, illumination power densities, molar amount, and morphology of the PTCDI film deposited on the interdigitated electrodes. The photocurrent relaxation was also performed on several other PTCDI nanofiber materials for comparative study. We conclude that the significant PPC effect in MP-PTCDI nanofibers can b...

A series of redox-active perylene tetracarboxylic diimide (PTCDI) derivatives have been synthesized and studied by electrochemical cyclic voltammetry and electrochemical scanning tunnelling microscopy break junction techniques. These PTCDI molecules feature the substitution of pyrrolidine at the bay (1,7-) position of perylene and are named pyrrolidine-PTCDIs. These moieties exhibit a small bandgap (2.1 eV) compared with the “normal” (unsubstituted) PTCDI molecule (2.5 eV). Pyrrolidine-PTCDIs were functionalized with different anchoring groups (thiol, amine, pyridine) for building metal–molecule–metal (m–M–m) junctions. The single-molecule conductance values of pyrrolidine-PTCDIs have been determined by analyzing a large number of molecular (m–M–m) junctions created between an STM tip and substrate using a statistical method. Furthermore, we studied the gate dependence of the single-molecule conductance by trapping a molecule between the two electrodes and recording the current as a function of electroche...

For photocatalytic removal of nitric oxide (NO), two major issues need to be addressed: incomplete oxidation of NO and deactivation of the photocatalyst. In this study, we aimed to solve these two problems by constructing an all-solid-state Z-scheme heterojunction (PI-g-C3N4) consisting of g-C3N4 surface modified with perylene imides (PI). PI-g-C3N4 exhibits significant enhancement in photocatalytic activity (in comparison to pristine g-C3N4) when examined for NO removal. More importantly, the Z-scheme charge separation within PI-g-C3N4 populates electrons and holes into the increased energy levels, thereby enabling direct reduction of O2 to H2O2 and direct oxidation of NO to NO2. H2O2 can further oxidize NO2 to NO3– ion at a different location (via diffusion), thus alleviating the deactivation of the catalyst. The results presented may shed light on the design of visible photocatalysts with tunable reactivity for application in solar energy conversion and environmental sustainability.

N-terminal proBNP (NT-proBNP) and cardiac troponin I (cTn I) are widely used for the diagnosis of myocardial injury, but have not been used for routine evaluation in heart failure (HF) population.To evaluate the prognostic utility of combination of NT-proBNP and cTn I in patients with HF, including serial NT-proBNP/cTn I measurements and discharge NT-proBNP/cTn I levels.A total of 610 patients presenting in our emergency department for acute HF were studied. The mortality and HF-related readmission were endpoints in the study. NT-proBNP and cTn I were tested on admission including first 5 consecutive days, and on discharge.A discharge cTn I cut-off value at 24 ng/L and discharge NT-proBNP cut-off value at 350 ng/L were determined. The cTn I level more than 24 ng/L and NT-proBNP level more than 350 ng/L are associated with increased risk for mortality and readmission (p 0.01). The mortality and HF-related readmission was significantly increased in patients with high cTn I + high NT-proBNP (p 0.05), high cTn I + low NT-proBNP (p 0.05), and low cTn I + high NT-proBNP (p 0.0%). The increased cTn I or increased NT-proBNP measured in the first 5 consecutive days were significantly associated with 60-day HF-related events (p 0.05), but the serial measurements did not have a predictive value of 1-year HF outcome.This study demonstrates that elevations of discharge cTn I and NT-proBNP are associated with increased 1-year mortality and HF-related readmission. Patients with increasing serial cTnI and NT-proBNP had increased risk for 60-day HF-related events. The two markers can act as independent predicators, and complete each other in prognostic utility of HF patients.