Filtering Effect Research Articles

Determination of acetaldehyde in Chinese Baijiu based on the light-activated oxidase-mimic activity of fluorine-containing carbon dots (dF-CDs)

Acetaldehyde (AH) is defined as a carcinogen, the widely existence in alcoholic beverages has led its determination an essential aspect related to human health. Fluorine doped carbon dots (dF-CDs) is developed, which process light-activated oxidase-mimic property and high stability at acidic condition. Under the UV irradiation, dF-CDs generate reactive oxygen species (ROS) to oxidize o-phenylenediamine (OPD) into 2,3-diaminophenazine (DAP), showing absorption peak at 450 nm and strong emission at 577 nm, meanwhile, the produced DAP quenches the original emission of dF-CDs at 455 nm via an inner filter effect (IFE). However, the introduction of AH inhibits such processes efficiently, thereby establishing a colorimetry and ratiometric fluorescence method for AH determination. Of note, this dual-responsive method has been used for the accurate AH determination in Chinese Baijiu. Therefore, the developed method not only provide a dual-sensing platform to determine AH, but also extends the applications of CDs in food analysis.

Lignin/carbon dots-embedded cellulose nanofibrils hydrogel: An effective, inexpensive and versatile platform for doxycycline adsorption and determination

Herein, a novel hydrogel, lignin/carbon dots-embedded cellulose nanofibrils hydrogel (LCCH), was fabricated for doxycycline (DOX) adsorption and determination. The adsorption characteristics of LCCH under various conditions were investigated. According to the Langmuir model fitting results, the maximum capacity of LCCH reached 1686 mg/g. Moreover, it exhibited excellent reusability, with an adsorption capacity maintained above 80.4 % after 5 cycles. Additionally, the LCCH demonstrated stable fluorescence properties, with DOX causing significant quenching of fluorescence attributed to both the internal filtration effect and static quenching. Within the ranges of 10–120 mg/L and 0.2–1.0 μg/L, the fluorescence of LCCH gradually decreased with the increasing concentration of DOX, reaching a limit of detection as low as 0.08 μg/L. Lastly, a cost analysis considering energy consumption and reagent prices demonstrated LCCH's cost-effectiveness as an adsorbent. Overall, this study presents a novel approach for designing and preparing an effective, inexpensive, and versatile hydrogel for the removal of antibiotics.

A label-free fluorescence sensing strategy based on gold nanoparticles assisted copper nanoclusters for the detection of aflatoxin B1 in cereals and peanuts

To effectively monitor the degree of aflatoxin B1 (AFB1) contamination in food and mitigate potential health risks to consumers eating food contaminated with AFB1, a label-free fluorescence aptamer-sensing strategy utilizing gold nanoparticles (AuNPs) was developed. Polyvinylpyrrolidone-copper nanoclusters (PVP-CuNCs) and AuNPs were selected as donor/acceptor pairs to convert the color signal change of AuNPs into fluorescence signal changes in PVP-CuNCs via the inner filter effect (IFE). In the presence of AFB1, the aptamer preferentially adsorbed with AFB1, and the AuNPs without aptamer protection changed color from red to blue under NaCl-induced aggregation. The green fluorescence of PVP-CuNCs recovered gradually. The developed strategy offers high sensitivity for the detection of AFB1, with a linear range of 0.02–20 μg L−1, and a low detection limit of 0.69 μg L−1. In addition, the strategy was successfully applied to real samples such as corn, rice, oats and peanuts, and the recovery rate was 93.4–106.2 %, which verified the reliability and applicability of this strategy. This strategy has the advantages of cost-effectiveness, high sensitivity, low detection limit and easy operation, providing a reference for sensitive and selective detection of mycotoxins contamination in food.

Performance evaluation of coloured filters on PV panels in an outdoor environment

AbstractThis study aims to investigate the effects of colour filters and tilt angles on the electrical output characteristics of solar photovoltaic modules. The experimental set‐up allowed for the evaluation of various combinations of colour filters and tilt angles by using a realistic simulation of solar panel installations. The various light spectrum wavelengths and energy levels were taken into account, keeping in mind any potential impacts on the solar cells' conversion efficiency. The results showed that compared to other filter combinations, the use of red colour filters with a 10% blockage rate and an optimal tilt angle led to a noticeable increase in electrical output. This result emphasises the value of colour filtering and tilt angle selection in raising solar photovoltaic systems' overall performance. When compared to the other filters, the red, orange, and yellow filters stand out due to their outstanding efficiency of around 84.98%, 84.08%, and 83.69%. However, the teal, green, and blue filters exhibit relatively low levels of efficiency of about 69.62%, 67.06%, and 58.52%, respectively. The distinct reaction shown by purple and pink filters, when subjected to tilt angle of 30 degrees, offers a potentially productive direction of enhancing the efficiency of PV panel.

Quantum confinement and energy filtering effect enhancing the thermoelectric power factor of InGaAs with buried ErAs nanoparticles

Quantum confinement and energy filtering effect enhancing the thermoelectric power factor of InGaAs with buried ErAs nanoparticles

Unipolar spin diodes and unipolar spin switches by Spin-Transfer torque in doped graphether

Spin switches are a fundamental component in the majority of spintronic devices, and have found extensive application in data storage, logical data manipulation, and signal processing. An essential aspect of constructing a spin switch is determining a stable two-dimensional material, which is easy to control and produce. Theoretical studies have shown that graphether is particularly promising due to its exceptionally high melting point and outstanding air stability. The band structure can be modified by doping, making it an important material for spin switch applications. In this paper, we have calculated the electromagnetic properties of doped graphether by first principles. Then we select a modified graphether with P-type and N-type doping configurations to construct magnetic tunnel junctions (MTJ). The results show that the MTJ exhibits perfect highly efficient spin switch as a result of spin reversal induced by spin-transfer torque (STT). In addition, our designed MTJ shows a remarkable rectification effect and spin filtering effect (SFE). According to our calculations, the modified graphether materials also show promise as two-dimensional spintronics materials.

Synthesis of four coordination polymers with Zn(II), Cd(II), Mn(II), or Co(II) ions and their application for fluorescence sensing toward nitenpyram, imidacloprid, and vitamin B2

Four new Zn(II)-, Cd(II)-, Mn(II)-, and Co(II)-based 1D to 2D coordination polymers (CPs) were synthesized from metal salts and 1,4-di(1-imidazol-1-yl)naphthalene (DIN) ligand via the coordination reaction under hydrothermal conditions with quantitative yields, namely, [Zn(SO4)(DIN)(H2O)] (CP-1), [Cd(NO3)2(DIN)] (CP-2), [Mn(SO4)(DIN)(H2O)3] (CP-3), and [Co(NO3)2(DIN)2(H2O)4] (CP-4). The CPs were analyzed and characterized using FT-IR, Elemental Analysis, TGA, SC-XRD, and PXRD. CP-1 was selected as a model sensor for fluorescence detection, and the sensor exhibited high quenching rates at two excitation wavelengths of λex = 230 and 290 nm, and at a single emission wavelength of λem = 350 nm. At these two different excitation wavelengths, CP-1 behaved differently during the sensing of pesticides, and the highest quenching rate was achieved by the sensor for nitenpyram (λex = 230 nm) and imidacloprid (λex = 290 nm). Furthermore, during the sensing of vitamins, CP-1 encountered a strong quenching effect toward vitamin B2. During the sensing processes, the inner filter effect (for nitenpyram, imidacloprid, and vitamin B2), fluorescence resonance energy transfer (for nitenpyram, imidacloprid, and vitamin B2), and photo-induced electron transfer (for vitamin B2) were the mechanisms responsible for fluorescence quenching.

Lateral flow assay with dual-emission nitrogen-doped carbon dots for ratiometric fluorescent determination of nitrite in food

Nitrite ion (NO2–), renowned for its potent antiseptic properties and color-preserving abilities, potentially leads to carcinogenesis and hypertension if consumed excessively. Herein, a ratiometric fluorescent probe exhibits specific response to NO2– using nitrogen-doped carbon dots (N-CDs) with a low detection limit (LOD) as low as 52 nM and a low quantification limit (LOQ) of 173 nM. Initially, the emission peaks at 495 nm and 415 nm decrease as result of the internal filtration effect (IFE). With further increasing NO2– concentration, the reaction between NO2– and N-CDs forms an azoic compound (N-CDs@NO2–), which promotes the instant quenching of the emission peak at 415 nm through fluorescence resonance energy transfer (FRET). Moreover, portable N-CDs/LFASs devices with smartphone are successfully applied to visually identify NO2– with the exceptional LOD, achieving excellent recoveries and high precision in real sample. Therefore, this newly N-CDs/LFASs offers a reliable means for the NO2– detection, showcasing potential applications.

Tunable and switchable multi-wavelength mode-locked fiber lasers induced by an optimized hybrid mode-locked composite filtering effect

A multi-wavelength mode-locked fiber laser can generate different wavelengths from a single laser cavity, offering potential as a dual-frequency comb and serving as an ideal light source for terahertz wave generation. We present an optimized hybrid mode-locked Er-doped fiber laser with flexible outputs: switchable and tunable dual-wavelength mode-locking, along with stable tri-wavelength mode-locking, which is achieved by introducing 0.69 m polarization-maintaining fiber and bent 200 m single-mode fiber to enhance intra-cavity birefringence and nonlinear effect to optimize the hybrid mode-locking effect, that is, build the composite filter effect. The dual-wavelength mode-locking not only covers a tunable wavelength range of 5 nm but also provides tunable wavelength intervals of 4-26 nm due to the composite filter effect. The formation dynamics of the tri-wavelength mode-locking can be switched either pair-by-pair or one-by-one. This approach enables the realization of wavelength interval tunable dual-wavelength mode-locking in mode-locked fiber lasers simply by introducing fiber without additional actions. Such a simple, compact fiber laser with tunable wavelength capabilities holds significant potential for diverse applications.

A noise-reduction algorithm for raw 3D point cloud data of asphalt pavement surface texture

High-precision 3D point cloud data have various analyses and application use cases. This study aimed to achieve a more precise noise reduction of the raw 3D point cloud data of asphalt pavements obtained using 3D laser scanning. Hence, a noise-reduction algorithm integrating improved Gaussian filtering and coefficient of variation was developed. A portable laser scanner was used to collect raw, high-precision 3D point cloud data of surface textures from pavement slab samples prepared with three different types of asphalt mixtures: AC-13, SMA-13, and OGFC-13, as well as asphalt from the test sections of the Yakang Expressway. An improved Gaussian filtering and Gaussian filtering that extracts noise using the coefficient of variation were used to filter out the obvious outlier noise and small-scale burr noise, respectively. Finally, the filtering effect of the proposed algorithm, Gaussian filtering, median filtering, and mean filtering on raw 3D point cloud data of pavement textures was evaluated through subjective visual quality and objective index evaluations. The results showed that the proposed algorithm filters out noise while preserving the micro-texture structure information, outperforming Gaussian filtering, median filtering, and mean filtering.

Development of a "Signal-On" Fluorescent Aptasensor for Highly Selective and Sensitive Detection of ZEN in Cereal Products Using Nitrogen-Doped Carbon Dots Based on the Inner Filter Effect.

This study aimed to develop a novel fluorescent aptasensor for the quantitative detection of zearalenone (ZEN), addressing the limitations of conventional detection techniques in terms of speed, sensitivity, and ease of use. Nitrogen-doped carbon dots (N-CDs) were synthesized via the hydrothermal method, resulting in spherical particles with a diameter of 3.25 nm. These N-CDs demonstrated high water solubility and emitted a bright blue light at 440 nm when excited at 355 nm. The fluorescence of N-CDs was quenched by dispersed gold nanoparticles (AuNPs) through the inner filter effect, while aggregated AuNPs induced by NaCl did not affect the fluorescence of N-CDs. The aptamer could protect AuNPs from NaCl-induced aggregation, but the presence of ZEN weakened this protective effect. Based on this principle, optimal conditions for ZEN detection included 57 mM NaCl, 12.5 nM aptamer concentration, incubation of AuNPs with NaCl for 15 min in Tris-EDTA(TE) buffer, and incubation of aptamer with ZEN and NaCl for 30 min. Under these optimized conditions, the "signal-on" fluorescent aptasensor for ZEN detection showed a linear range of 0.25 to 200 ng/mL with a low detection limit of 0.0875 ng/mL. Furthermore, the developed aptasensor exhibited excellent specificity and could rapidly detect ZEN in corn flour samples or corn oil, achieving satisfactory recovery rates ranging from 84.7% to 108.6%. Therefore, this study presents an economical, convenient, sensitive, and rapid method for accurately quantifying ZEN in cereal products.

Polarity-controllable magnetic skyrmion filter

Abstract The skyrmion generator is one of the indispensable components for the future functional skyrmion devices, but the process of generating skyrmion cannot avoid mixing with other magnetic textures, such as skyrmionium and nested skyrmion bags. These mixed magnetic textures will inevitably lead to the blockage of skyrmion transport and even the distortion of data information. Therefore, the design of an efficient skyrmion filter is of great significance for the development of skyrmion-based spintronic devices. In this work, a skyrmion filter scheme is proposed, and the high-efficiency filtering function is demonstrated by micromagnetic simulations. The results show that the filtering effect of the scheme depends on the structure geometry and the spin current density that drives the skyrmion. Based on this scheme, the polarity of the filtered skyrmion can be controlled by switching the magnetization state at the output end, and the “cloning” of the skyrmion can be realized by geometric optimization of the structure. We believe that in the near future, the skyrmion filter will become one of the important components of skyrmion-based spintronic devices in the future.

Energy Filtering in Doping Modulated Nanoengineered Thermoelectric Materials: A Monte Carlo Simulation Approach.

Using Monte Carlo electronic transport simulations, coupled self-consistently with the Poisson equation for electrostatics, we explore the thermoelectric power factor of nanoengineered materials. These materials consist of alternating highly doped and intrinsic regions on the scale of several nanometers. This structure enables the creation of potential wells and barriers, implementing a mechanism for filtering carrier energy. Our study demonstrates that by carefully designing the nanostructure, we can significantly enhance its thermoelectric power factor compared to the original pristine material. Importantly, these enhancements stem not only from the energy filtering effect that boosts the Seebeck coefficient but also from the utilization of high-energy carriers within the wells and intrinsic barrier regions to maintain relatively high electronic conductivity. These findings can offer guidance for the design and optimization of new-generation thermoelectric materials through improvements in the power factor.

Effective Noise Reduction Filters for Precise Temperature Measurement Using Brillouin Distributed Optical Fiber Sensors

This study explores the effectiveness of various noise reduction filters in accurately measuring temperature distributions over a 38.2 km single-mode fiber (SMF). Brillouin optical time-domain analysis (BOTDA) sensor is utilized to gather Brillouin gain spectra (BGSs), which are denoised using bilateral filter (BF), guided filter (GF), adaptive Wiener filter (AWF), non-local means filter (NLMF), average filter (AF) and disc filter (DF). The temperature distributions over the SMF are then determined by applying least-squares curve fitting (LSCF). The study assesses the efficacy of noise reduction filters considering signal-to-noise ratio (SNR), uncertainty in temperature measurement (UTM), experimental spatial resolution (ESR) and signal processing speed (SPS). Among six different filters, NLMF outperforms other filters which can provide SNR improvement of 10.22 dB for which the UTM can be improved by 58.93% without deteriorating the ESR of the sensor. The noise reduction using such filter can also provide 6.2% faster SPS. Therefore, NLMF can be considered as an effective noise reduction filter for the precise temperature measurement using BOTDA sensors. DUJASE Vol. 8 (1) 42-50, 2023 (January)

Au nanoparticles decorated graphitic carbon nitride nanosheets as a sensitive and selective fluorescence probe for Fe3+ and dichromate ions in aqueous medium

Graphitic carbon nitride mutated with metal nanoparticles has captivated great interest as an effective fluorescent sensor for the detection of harmful ions present in water. In the present work, bulk-gCN was synthesized using melamine as precursor, and further Au-gCN nanocomposite were fabricated via in-situ direct reduction deposition method. The structural, morphological, compositional, stability and optical properties of bulk gCN and Au-gCN nanocomposite were examined using various scattering and spectroscopic techniques such as HRTEM, XPS, XRD and SEM. The synthesized bulk gCN straggles during selectivity studies with different cations and anions because of its uneven surface morphology, however in Au-gCN gold nanoparticles are uniformly distributed on the gCN sheets which results in its enhanced selectivity over bulk gCN. This leads to the fabrication of an optical sensor for Fe3+ and Cr2O72− ions with limit of detection of 4.62 and 2.77 μM, respectively. The sensing of Fe3+ ions corresponds to the photoinduced electron transfer (PET) mechanism, while the detection of chromate species is associated with an inner filter effect (IFE). The practical applicability of the sensor was also evaluated for different environmental water samples. The high stability, sensitivity, and specificity of Au-gCN nanocomposite make it a potential fluorescent probe for Fe3+ and Cr2O72− ions in water samples.

High polarization sensitivity passive spin Photogalvanic devices based on 2D perovskite CsMnBr4/CsSbCl3Br/CsMnBr4 heterojunction

In recent years, Dion-Jacobson (D-J) perovskite has been extensively studied. In order to further study the application of D-J perovskite materials in spin-optoelectronic multifunctional devices, this paper is based on CsSbCl3Br and CsMnBr4, a zero-band gap semi-metallic material with the same ferromagnetic ground state and the same crystal structure. In this paper, put forward with transverse CsMnBr4/CsSbCl3Br/CsMnBr4 heterojunction optoelectronic devices. The characteristics of photocurrent are discussed using parallel configuration (PC) and anti-parallel configuration (APC) magnetoelectric poles under two conditions: vertical incidence of linearly polarized light and elliptically polarized light utilizing density functional theory and the non-equilibrium Green’s function method. The results reveal that the device can achieve complete spin polarization photocurrent, pure spin current, perfect spin filtering effect, and excellent spin valve effect, with high extinction ratios. Under linearly polarized light, the maximum extinction ratio reaches 2747 for the PC configuration and 5200 for the APC configuration. For elliptically polarized light, the extinction ratio is 739 for the PC configuration and reaches a maximum of 240 for the APC configuration. These results indicate that the lateral CsMnBr4/CsSbCl3Br/CsMnBr4 heterojunction has broad multi-functional application prospects in the field of optoelectronics and spintronics.

Dual-phase competitive behavior in N-type Sn–Bi–Te thermoelectric films achieving high thermoelectric performance

The dual-phase competitive behavior is introduced as an effective strategy to optimize the physical and chemical properties of N-type Bi2Te3 thermoelectric (TE) materials. Controllable SnTe-embedded Bi2Te3 nanocomposites can be synthesized with the addition of excessive Sn into Bi2Te3 by tuning the crystallization behavior under proper thermal heating temperature. Notably, the precipitation temperature of Bi2Te3 increases from 473 ​K for Sn20.9(Bi2Te3)79.1 to 573 ​K for Sn34.4(Bi2Te3)65.6, expanding the controllable temperature span for the presence of SnTe phase. The second-phase nanoprecipitate SnTe can improve electrical conductivity by competing with the Bi2Te3 phase, achieving an increase of four orders of magnitude at the critical temperature of ∼500 ​K. Simultaneously, it increases the interfacial energy filtration effect between nanocrystalline grains, decoupling electrical parameters between conductivity and Seebeck coefficient. Consequently, the high power factor of ∼147 ​μW/mK2 at 650 ​K for optimized Sn26.6(Bi2Te3)73.4 films can be obtained, which is more than twice that of the pure Bi2Te3 material. Our work demonstrates a new physical mechanism to unravel the complicated structure-property relationship by dual-phase competitive behavior during phase transition. This study fills the gap in knowledge on the effects of the SnTe phase regarding the Bi2Te3 system and provides guidance for the innovative design of high-performing inorganic thermoelectrics.

Three in one: coordination-induced emission for inherent fluorescent Al-MOF synthesis combined with inner filter effect@aggregation-induced emission mechanisms for designing color tonality and ratiometric sensing platforms.

Three phenomena, namely coordination-induced emission (CIE), aggregation-induced emission (AIE), and inner filter effect (IFE), were incorporated into the design of a ratiometric and color tonality-based biosensor. Blue fluorescent Al-based metal-organic frameworks (FMIL-96) were prepared from non-emissive ligand and aluminum ions via CIE. Interestingly, the addition of tetracycline (TC) led to ratiometric detection and color tonality, as the blue emission at 380nm was quenched (when excited at 350nm) due to IFE, while the green-yellowish emission at 525nm was enhanced due to AIE. Based on that, an ultra-sensitive visual-based color tonality mode with smartphone assistance was developed for detection of TC. The sensor exhibited a linear relationship within a broad range of 2.0 to 85.0μMTC with a detection limit of68.0nM. TC in milk samples was quantified with high accuracy and precision. This integration of smartphone and visual fluorescence in solution isaccurate, reliable, cost-effective, and time-saving, providing an alternative strategy for the semi-quantitative determination of TC on-site.

An investigation of the Excitation Wavelength-Dependent Dynamic Changes in the Mechanism of Detection of Picric Acid using Pyrene-Based Donor-Acceptor Systems.

Picric acid (PA) is an important industrial feedstock and hence the release of industrial effluents without proper remediation results in its buildup in soil and water bodies. The adverse effects of PA accumulation in living beings necessitate the development of efficient methods for its detection and quantification. Herein, we describe pyrene-based fluorescent sensors for PA, where pyrene is appended with electron-withdrawing groups, malononitrile, and 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene) malononitrile (DCDHF). These molecules displayed the typical emission of pyrene monomers, as well as a broad red-shifted emission resulting from an intramolecular charge transfer (ICT) in the excited state. Both the emissions displayed a turn-off response to PA with high selectivity and sensitivity and the lowest limit of detection was estimated as 27 nM. To prove the feasibility of on-site detection, test paper strips were prepared, which could detect PA up to 4.58 picograms. Using a combination of experimental and theoretical studies the mechanism of the detection was identified as primary/secondary inner filter effect, oxidative photoinduced electron transfer, or a combination of both depending on the excitation wavelength. Interestingly, the contribution of each of these mechanisms to the total quenching process varied with a change in the excitation wavelength.

Enhancing Solar Photovoltaic Panel Performance in India's Tropical Climate: An Experimental Study on the Influential Effects of Optical Filters

<p>Due to the increasing global energy demand and consequent climate change from burning fossil fuels, researchers are getting more focused on renewable energies as a potential solution to the world's energy problems. Solar energy is a prominent form of sustainable energy. The solar photovoltaic power generation system’s electrical performance is negatively influenced by several factors, including the impact of solar irradiance, incident angle, temperature, dust accumulation on the top of the solar cell, cracks in the solar panel, shadowing, shunt resistance, solar cell materials, load mismatch, maintenance and cleaning schedule, spectral mismatch loss, and cable loss. The direct environmental factors that have the biggest impact on efficiency are the effects of sun irradiance and temperature. This empirical investigation examined the impact of optical filters on the electrical efficiency of a 40W polycrystalline solar PV panel in India while considering real-time ambient conditions. Through the utilization of an optical filter, the solar PV panel's temperature is diminished, hence enhancing the output power of the solar panel. Based on the experimental findings, the utilization of a transparent plexiglass sheet equipped with a coolant system installed on the solar panels leads to a drop in the average operating temperature of the solar PV module by up to 6°C. Additionally, the output power is enhanced by up to 10W in comparison to the reference solar panel’s output performance.</p>