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Phosphate is widely used in industry and agriculture fields. However, excess accumulation of PO43− causes several adverse effects on the human body and ecological environment. Consequently, it is important to develop a simple method for the detection of PO43− concentration in the ecological environment and in vivo. Herein, two caffeic acid derivative-based fluorescence probes (BAM-HM and BAM-HH) were developed for the detection of phosphate. The BAM-HM probe could detect phosphate via fluorescence enhancement at 500 nm, with the detection limit being 0.612 µM. Meanwhile, the BAM-HH probe showed a significant turn-on signal at 450 nm after the addition of phosphate, and the detection limit was calculated to be 0.318 µM. The sensing mechanism was determined by 1H NMR and MS. Furthermore, the two probes (BAM-HM and BAM-HH) were applied for PO43−detection in living cells and water samples. [ABSTRACT FROM AUTHOR]

This paper investigates a highly selective frequency selective rasorber (FSR) utilizing interdigitated resonators, characterized by a passband exhibiting low insertion loss (IL) and the introduction of a second-order passband response in the lossless layer enhances selectivity on both sides of the passband. The lossy unit is implemented by inserting interdigitated resonators on an octagonal ring loaded with lumped resistors, while the lossless layer is constructed with a five-layer structure. Simulation results demonstrate a low IL value of 0.78 dB at 3.5 GHz. At vertical incidence, the S 21>−3 dB bandwidth ranges from 3.41 to 3.67 GHz, and the S 11<−10 dB range spans from 2.2 to 8.2 GHz, obtaining two absorption bands on either side of the passband, with absorption rates exceeding 80%. The operating frequency bands are 1.95–3.27 GHz and 3.8–8.4 GHz. The designed FSR exhibits polarization insensitive. To validate simulation results, a prototype FSR was fabricated and tested, with experimental data aligning with simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a highly selective quad-band frequency selective surface (FSS) with ultra-wideband rejection is presented. The proposed FSS structure was developed by cascading five metallic layers by three thin dielectric substrates. The five metallic layers are composed of two bent slot layers, two metallic square rings, and a metal patch. The dimensions of the unit cell are 0.13 λ 0 × 0.13 λ 0 × 0.18 λ 0 ( λ 0 is the free-space wavelength at the first operating frequency). The proposed structure achieves four transmission bands and has two wide stop-bands located at 1 to 5.5 GHz and 14 to 40 GHz, with a suppressed transmission coefficient below −20 dB. In order to verify the simulation results, an FSS prototype was fabricated and measured. It can be observed that the measured results are in favorable agreement with the simulation results. Its multiple narrow passbands and highly selective and ultra-wideband rejection properties ensure that our design can play a significant role in narrowband antennas, spatial filters, and many other fields. [ABSTRACT FROM AUTHOR]

In this paper, a highly selective quad-band frequency selective surface (FSS) with ultra-wideband rejection is presented. The proposed FSS structure was developed by cascading five metallic layers by three thin dielectric substrates. The five metallic layers are composed of two bent slot layers, two metallic square rings, and a metal patch. The dimensions of the unit cell are 0.13λ0× 0.13λ0× 0.18λ0 (λ0 is the free-space wavelength at the first operating frequency). The proposed structure achieves four transmission bands and has two wide stop-bands located at 1 to 5.5 GHz and 14 to 40 GHz, with a suppressed transmission coefficient below −20 dB. In order to verify the simulation results, an FSS prototype was fabricated and measured. It can be observed that the measured results are in favorable agreement with the simulation results. Its multiple narrow passbands and highly selective and ultra-wideband rejection properties ensure that our design can play a significant role in narrowband antennas, spatial filters, and many other fields.

In this paper, highly selective dual-mode microstrip bandpass filters (BPFs) are presented utilizing novel square patch resonator loaded with short via and periodic metallic vias array. Characteristics of the patch resonator are studied, and a new nondegenerate dual-mode patch resonator operating with the second and third higher-order modes is proposed. A two-pole BPF based on one dual-mode patch cavity is analyzed, and two transmission zeros (TZs) are produced. To realize higher-order filtering responses, four-pole BPFs with two cascaded dual-mode patch resonators are proposed, and different cascaded methods of two dual-mode patch resonators by a λ g /4 microstrip connecting line (MCL) are analyzed and compared to maintain high selectivity and small size. For the demonstration, two four-pole filters with the center frequency at 3.3 GHz and five transmission zeros is designed, fabricated and measured. [ABSTRACT FROM AUTHOR]

A triethylamine gas sensor with humidity resistance, high selectivity, and high response is designed. Chromium oxide particles were prepared by heating them in a water bath at 80 °C. Pt/Cr2O3 nanoparticles were obtained by sodium borohydride reduction. The structure morphology of nanoparticles was characterized by some methods. The gas response test results showed that the modification of Pt improved the response value and selectivity of Cr2O3 to triethylamine. It was found that Cr2O3–2Pt nanoparticles had the best performance, and at the optimum operating temperature of 160 °C, its response value reached 200, 68 times that of Cr2O3 (S = 2.95). In addition, the modification of Pt made Cr2O3–2Pt nanoparticles had a wide range of humidity applications. The mechanism of gas response is explained by using the Schottky barrier and hole accumulation layer model of Pt and Cr2O3 contact and energy band theory. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide production through the electrochemical two-electron oxygen reduction presents a compelling alternative to the anthraquinone process due to the cheap starting materials and low operating temperature and pressure. Transition metal species featuring with multi-active sites, offer high electrochemical activity and selectivity. MXenes, distinguished by excellent electrical conductivity and the two-dimensional structure facilitating smooth ion transportation, further enhance the prospects of this production approach. In this study, three Mo-based MXenes were synthesized: Mo 2 TiC 2 F x , Mo 2 Ti 2 C 3 F x and Mo 2 CF x. Among these, Mo 2 TiC 2 F x emerged as the most promising catalyst for 2e−ORR, achieving a remarkable H 2 O 2 yield of up to 0.54 mol·g cat −1·h−1. Moreover, it also exhibits a high H 2 O 2 selectivity ranging from 81.3 % at 0.2 V to 94.1 % at 0.6 V vs. RHE, coupled with an impressive faradaic efficiency of 76.4 % at 0.4 V using H-cell. Further analysis indicates that the superior 2e−ORR performance can be attributed to the presence of metallic Mo on the surface of Mo 2 TiC 2 F x. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel highly ICT based selective receptor for biologically significant Mg(II) on ferrocene platform has been synthesized and characterized. • The sensing ability of receptor towards Mg(II) was successively investigated in aqueous acetonitrile. • The experimental findings were well supported by computational studies. • The obtained nanomolar detection limit and association (K a) constant are much comparable to reported molecules for Mg(II). • The receptor was employed in bio-imaging studies for recognition of Mg(II) in HeLa cells. • Also, the receptor was explored in sensing applications through low cost test strips and TLC plates for the recognition of Mg(II). Qualitative and quantitative analysis of magnesium at concentration levels as low as parts per billion (ppb) is a basic, fundamental and practical concern. The present study displays the design and synthesis of a novel specific receptor (E)-3-((2-hydroxynaphthalen-1-yl)methylene)amino)-2-ferrocenyl-2,3-dihydroquinazolin-4(1H)-one (HnFQz) for selective recognition of Mg(II). The HnFQz shows turn-on fluorescence response from colorless to yellowish green after treatment with Mg(II) at λ max. 499 nm in aqueous acetonitrile. The experimental findings were well supported by theoretical results. The ESI-MS spectrometry and the Job's experimental results confirm the formation of 1:1 complex between HnFQz and Mg(II). Further study demonstrates the detection limit and association constant of HnFQz for Mg(II) and were found to be 23.24 nM and 1.48 × 107 M−1 respectively. The practical application of receptor towards recognition of Mg(II) was explored through economically viable test strips and bio-imaging studies. The excellent outcome of present research suggests that the receptor HnFQz could act as an efficient Mg(II) test kit. [ABSTRACT FROM AUTHOR]

• Iron sulfide nanoparticles was biosynthesized by Pinus massoniana Lamb. • nFeS showed a highly selectively recover Y(Ⅲ) from mining wastewater. • The adsorption of Y(Ⅲ) was predominant by the capping layer. • The result showed that effective desorption of Y(Ⅲ) from mining wastewater. The selective recovery of rare earth elements (REEs) from mining wastewater has become a hot research topic due to the increasing industrial value of REEs. Herein, biosynthetic iron sulfide nanoparticles (nFeS) were deployed as a superior adsorbent to selectively recover Y(Ⅲ) from mining wastewater. The maximum adsorption efficiency achieved for of Y(Ⅲ) by nFeS was 81.2 % compared to only 38.7 % for Eu(Ⅲ) and 20.8 % for Mn(Ⅱ), demonstrating that nFeS had a high selective adsorption for Y(Ⅲ). To understand the origins of the high selectivity of nFeS, the removal of REEs by the capping layer and the FeS-core were separately investigated. Specifically, given the hard and soft acid base principle (HASB) and the square antiprism coordination geometry of Y(Ⅲ), the adsorption of Y(Ⅲ) by the capping layer was predominantly attributed to C O and –NH 2 serving as a monodentate ligand to strongly chelate with Y(Ⅲ), while Y(Ⅲ) interacted with Fe–O on the FeS-core and –COOH more via ion-exchange with Y(Ⅲ). Collectively, cooperative interactions between the capping layer and FeS-core resulted in the overall highly selective adsorption of Y(Ⅲ) by nFeS, suggest this approach has significant potential for future practical remediation and recovery applications to Y(Ⅲ) rich mining wastewaters. [ABSTRACT FROM AUTHOR]

Abstract Background Pyrolysis has attracted growing interest as a versatile means to convert biomass into valuable products. Wheat straw has been considered to be a promising biomass resource due to its low price and easy availability. However, most of the products obtained from wheat straw pyrolysis are usually of low quality. Hot soda extraction has the advantage of selective dissolution of lignin whilst retaining the carbohydrates. This can selectively convert biomass into high-quality desired products and suppress the formation of undesirable products. The aim of this study was to investigate the pyrolysis properties of wheat straw under different hot caustic pretreatment conditions. Results Compared with the untreated straw, a greater amount of gas was released and fewer residues were retained in the extracted wheat straw, which was caused by an increase in porosity. When the NaOH loading was 14%, the average pore size of the extracted straw increased by 12% and the cumulative pore volume increased by 157% compared with the untreated straw. The extracted straw obtained from the 14% NaOH extraction was clearly selective for pyrolysis products. On one hand, many lignin pyrolysis products disappeared, and only four main lignin-unit-pyrolysis products were retained. On the other hand, polysaccharide pyrolysis products were enriched. Both propanone and furfural have outstanding peak intensities that could account for approximately 30% of the total pyrolysis products. However, with the excessive addition of NaOH (i.e. > 22% w/w) during pretreatment, the conversion of bio-gas products decreased. Thermogravimetric and low-temperature nitrogen-adsorption analysis showed that the pore structure had been seriously destroyed, leading to the closing of the release paths of the bio-gas and thus increasing the re-polymerisation of small bio-gas molecules. Conclusions After suitable extraction (14% NaOH loading extraction), a considerable amount (25%) of the soluble components dissolved out of the straw. This resulted in an increase in both pore size and volume. This condition appeared to be optimally selective for the release of value-added pyrolysis products such as furfural, ketones and lignin monomer units. However, excessive addition of alkali (22%) for extraction could change the original interior structure, resulting in a decrease in both pore size and volume. This interior structure modification limited the release of pyrolysis products, and greater carbonisation occurred.

Intelligent gas sensors based on the layered transition metal dichalcogenides (TMDs) have attracted great interest in the field of gas sensing due to their multiple active sites, fast electron, mass transfer capability and large surface-to-volume ratio. However, conventional TMDs-based sensors typically work at elevated temperature in inert atmosphere, which would largely limit the corresponding practical applications. Herein, novel oxygen-doped MoSe2 hierarchical nanostructures composed of ultrathin nanosheets with large specific surface area have been designed and generated typically at 200 °C in air for fast and facile gas sensing of trimethylamine (TMA), effectively. Benefited from the gas-accessible hierarchical morphology and high surface area with abundant nanochannels, highly sensitive and selective detection of trace TMA has been achieved under ambient condition, and as detected the theoretical limit of detection (LOD) is 8 ppb, which is the lowest for TMA detection under ambient condition among the reported studies. The mechanism of oxygen doping on the improved gas-sensing performance has been investigated, revealing that the oxygen doping could greatly optimize the electronic structure, thus regulate the Fermi level of MoSe2 as well as the affinity between TMA molecule and sensor surface. It is expected that the oxygen doping strategy developed for the highly efficient gas sensors based on TMDs in present work may also be applicable to other types of gas-sensing semiconductors, which could open up a new direction for the rational design of high-performance gas sensors working under ambient condition. [ABSTRACT FROM AUTHOR]

In this study, we synthesized nanostructured zinc oxide (ZnO) by using various concentrations (0–0.05 M) of cetyltrimethylammonium bromide (CTAB) as a surfactant to optimize its morphology for gas sensor applications. The optimization process was used to elucidate the morphology effects (rod-shaped and flower-shaped morphologies). The morphologies were investigated through scanning electron microscopy, in which the assembly of nanorods leading to a spherical microstructure with a CTAB concentration of 0.005 M was observed. Brunauer–Emmett–Teller isotherm measurements revealed a surface area of 7.928 g/m2 for the flower-like morphology, which was relatively higher than those of other CTAB-assisted morphologies. Such morphological features were expected to contribute toward high-performance gas-sensing. The effect of morphology variation on the resistance of ZnO microstructures was used for gas measurements. Among the varied morphologies, a sample with a spherical flower-shaped morphology exhibited a very high response at low temperatures (~29 at 25 °C) toward NO X gas (0.75 ppm) and a high selectivity toward NO x among ammonia (NH 3), toluene (C 6 H 5 CH 3), carbon monoxide (CO), acetone (CH 3 COCH 3), and ethanol (C 2 H 5 OH). Raman and photoluminescence spectroscopy analyses unraveled the presence of a high density of oxygen vacancies in the sample, thereby suggesting a close link between the defective nature of the sample and the high response of the flower-like ZnO at low temperatures. Development of selective and sensitive ZnO-based NO X gas sensors operating at low temperatures.Synthesis of spherical flower-shaped ZnO with CTAB as the sensing material.Excellent sensitivity of 29 toward NO X at 25 °C.Low concentration (0.19–0.74 ppm) detection of NO X at 25 °C. Highly selectivity toward NO X among NH 3 , C 6 H 5 CH 3 , CO, CH 3 COCH 3 , and C 2 H 5 OH at 25 °C. Image 1 [ABSTRACT FROM AUTHOR]

The organic ligand 1,10-phenanthroline-2,9-dicarboxylic acid (H2L) was used to react with ZnSO4·7H2O at 140 °C for two days to obtain the complex [Zn6(L)6(H2SO4)]·3CH3CN·Et3N (1). The structure of complex is confirmed by X-ray crystallography, TG and PXRD. The structure suggested that six ligands chelated with six Zn2+ ions. Every five-coordinated Zn(II) ion is surrounded by two N atoms and three O atoms (one sulfate radical or three ligands) with the N2O3 coordination environment. Each Zn(II) ion in the structure of complex 1 binds only one L2− ligand. The metal center Zn2 and Zn3 are bridged by SO42−. The photoluminescence of complex 1 is obvious. Moreover, in the presence of Cd2+ ions, the complex exhibits an efficient recognition ability, and it realizes the recognition of toxic metal ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • We have designed a new "turn-on" fluorescent probe S-YHS based on a functional polysiloxane. • We introduced a structure that can be oriented to the organelles of the lipid droplet, and can effectively detect the concentration level of ONOO− in the lipid droplet. • S-YHS exhibits excellent cell penetration and can enter Hela cells quickly. • S-YHS is biocompatible and photostable, and the detection of ONOO− is evident in live cells and zebrafish imaging. Peroxynitrite (ONOO−) is a highly reactive nitrogen species formed by the combination of superoxide anion radicals and nitric oxide radicals. However, lipid droplets, which are important cellular organelles involved in metabolism, contain a variety of enzymes. The presence of high concentrations of ONOO− can lead to the inactivation of enzymes and other substances within lipid droplets, resulting in various diseases. Therefore, it is imperative to develop methods for detecting ONOO− in order to understand its physiological and pathological mechanisms. In this study, we have successfully developed a polysiloxane platform by modifying the side-chain NH 2 group. This platform incorporates naphthylimide, which exhibits an ICT (intramolecular charge transfer) mechanism, as well as triphenylamine derivatives that specifically target lipid droplets. By utilizing this polysiloxane platform, we have created a fluorescent probe (S-YHS) that selectively and sensitively detects ONOO− within lipid droplets. The development of this lipid droplet-targeting ONOO− fluorescent probe has significant implications for understanding the role of ONOO− in various diseases. Its high selectivity and sensitivity make it a valuable tool for studying the physiopathological mechanisms associated with ONOO−. [ABSTRACT FROM AUTHOR]

The production of H 2 O 2 by oxygen reduction reaction (ORR) is low energy consumption and environmentally friendly. Pd/C is an effective electrocatalyst for oxygen reduction, while its selectivity is low due to a tendentious four-electron pathway ORR process. The limited reserves of palladium and inevitable corrosion issue of carbon support add extra obstacles toward practical application. In this work, Pd nanoparticles with 3–5 nm were synthesized on MXene sheets. Results indicated that Pd/MXene exhibited 3.5∼4.2 times ring current than Pd/C and much higher H 2 O 2 selectivity. The H 2 O 2 yield of Pd/MXene was measured to be 1.43 mol g−1 h−1. The excellence in electrochemistry was from the synergistic effect of Pd and MXene. The existence of MXene increases metallic Pd on the surface. This study on MXenes as supports of Pd nanoparticles for two-electron oxygen reduction provides extensive reference significance to H 2 O 2 generation. [ABSTRACT FROM AUTHOR]

Humidity sensors are widely used in agriculture. Graphene and reduced graphene oxide (rGO) have become high-performance humidity-sensitive materials. However, there are many interferences in agricultural production, such as smoke from burning stalks and animal waste. In fact, graphene and rGO are sensitive to a variety of gases, resulting in poor anti-interference ability of existing humidity sensors. In this work, by simply spraying a layer of graphene oxide (GO) on the surface of rGO, the cross-sensitivity to 3.4 ℃ temperature rise reduces from −0.3%/RH% to −0.2%/RH%, the cross-sensitivity to 683 ppm ammonia significantly reduces from 2.5%/RH% to 0.08%/RH%, and the cross-sensitivity to 34 ppm ethanol reduces from −0.2%/RH% to nearly 0. The encapsulated sensor still maintains the high sensitivity (0.37%/% RH) and fast response (1.8 s response/4.5 s recovery) of the original humidity sensor. The resistance to temperature interference is due to GO's weak thermal conductivity. The resistance to gas interference stems from that the adsorbed water molecules between the GO interlayers block the entry of other gases to some extent. Finally, field tests show that the encapsulated rGO humidity sensor can resist the interference of straw smoke and pig manure, which has great practical application value. [Display omitted] • An encapsulation strategy of humidity sensor for enhanced anti-interference ability. • Anti-temperature and anti-gas interference have been achieved. • High sensitivity and fast response/recovery are maintained. • The structure of the GO layer affects the anti-interference performance. • The encapsulated sensor can resist the interference of straw smoke and pig manure. [ABSTRACT FROM AUTHOR]

An efficient material is always welcoming for the water treatment due to the need of clean water to safe the human health. The conjugate adsorbent (CJA) was fabricated by functional ligand embedded onto the highly porous silica material for selective lead (Pb(II)) ion monitoring and removal from wastewater. The study was achieved not only investigating the beginning material but also the performing extrusion as novel conjugate material, this defining the material novelty of this study considers to the modern state-of-art. The fabricated material was characterized in all aspects and then the experimental works for Pb(II) ion assessing were carried in batch mode. The CJA was exposed the color and signal intensity upon addition of Pb(II) ion from low to high concentrations. The optimum pH was considered at 5.50 based on the sensitivity, the color formation ability and high adsorption of Pb(II) ion. The determined limit of low detection was 0.18 μg/L, which was the extraordinary performance for the Pb(II) ion monitoring ability by the CJA. The adsorption efficiency, specific attention was remunerated to the influence of solution pH, reaction time, foreign ion, initial Pb(II) amounts and regeneration. The CJA was exhibited high kinetic performances and showed high adsorption Pb(II) ion compared with the different forms of material. The adsorption was completely fitted with the Langmuir adsorption as defining the monolayer coverage as expected of the homogeneous porosity of the CJA. The maximum adsorption was determined as high as 175.16 mg/g. In addition, the foreign ions were not affected in the Pb(II) adsorption by the CJA, and the adsorbent was regenerated using 0.20 M HCl for several cycles used without significant loss of the initial performance. Considering these advantages, the CJA demonstrated the potential low-cost material for competitive use in wastewater remediation, especially in the developing countries. Unlabelled Image • Novel conjugated adsorbent was fabricated for efficient Pb(II) ion capturing. • The material was exhibited specific selectivity towards the Pb(II) ion only. • The diverse ions were not interfered both in the case of monitoring & removal. [ABSTRACT FROM AUTHOR]

Abstract A new series of fluorescent chemosensors (7a - 7f) based on a core skeleton of 2-(benzylideneamino)-4,5,6,7-tetrachloro-3′,6′-dihydroxyspiro-[isoindoline-1,9′-xanthen]-3-one was synthesized and characterized by FT-IR, NMR and mass spectrometric techniques. The sensitivity and selectivity of probes (7a - 7f) for Cu2+ ions were investigated by colorimetric, UV-vis absorption, fluorescence emission spectral studies and electrochemical analysis. These optical probes exhibited higher sensitivity and selectivity towards Cu2+ ions in DMSO solution over various other metal cations under consideration. Induced changes were observable by naked-eye. Based on fluorescence titration spectra and Job's-plot, it was found that the complexes formed between probes (7a - 7f) and Cu2+ ions were in 1:1 stoichiometric ratio. The detection limit for chemosensors (7a - 7f) were calculated to be 3.0834 × 10−7–3.6425 × 10−7 M. Graphical Abstract A credible mechanism for selective detection of Cu (II) ions Unlabelled Image Highlights • The probes (7a - 7f) are "Turn-On" chemosensors based on xanthene moiety. • The fluorescent probes (7a - 7f) exhibit good selectively for Cu2+ ions. • The probes (7a - 7f) provided naked-eye detection for Cu2+ ions in a wide range of pH. [ABSTRACT FROM AUTHOR]

Abstract A Mn(II)-based metal-organic framework (MOF) {[Mn 3 (L 1 ) 2 (L 2 ) 2 (H 2 O) 8 ]·4H 2 O} n (1) (H 3 L 1 = 6-sulfonaphthalene-1,4-dicarboxylic acid, L 2 = 1,3,5-tris(1 H -imidazol-1-yl)benzene), has been designed based on host-guest interaction. Single crystal X-ray diffraction indicated that 1 was a two-dimensional (2D) network with uncoordinated carboxyl and sulfo groups. The compound showed high selective adsorption of Congo red (CR) from water in two minutes. Moreover, the results also revealed that the maximum adsorption capacity of 1 can reach 1393 mg g−1 and 1 can be recovered conveniently. Graphical abstract A Mn(II) metal-organic framework has been designed based on host-guest interaction and it can adsorb CR high selectively from water. fx1 [ABSTRACT FROM AUTHOR]