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Polarization property of high harmonics generated from nitrogen molecule by bichromatic counter-rotating circularly polarized laser fields
摘要： Along with the rapid appearance of superbacteria with multidrug resistance, it is a challenge to develop new antibacterial materials to address this big issue. Herein, we report a novel amine group-modi?ed fullerene derivative (C70?(EDA)8), which reveals a high performance in killing superbacteria, and most importantly, it shows negligible toxicity to the mammalian cells. The strong antibacterial ability of this material was attributed to its unique molecular structure. On one hand, amino groups on the EDA part make it easy to a?x onto the outer membrane of multidrug resistance Escherichia coli by electrostatic interactions. On the other hand, the hydrophobic surface on the C70 part makes it easy to form a strong hydrophobic interaction with the inner membrane of bacteria. Finally, C70?(EDA)8 is nontoxic for mammalian cells due to di?erent distributions of the negative charges in the cell membrane. In vivo studies indicated that C70?(EDA)8 mitigated bacterial infection and accelerated wound healing by regulating the immune response and secretion of growth factors. Our amine group-based fullerene derivatives are promising for clinical treatment of wound infection and o?er a new way to ?ght against the superbacteria.
关键词： cytoprotection,wound healing,selectivity,superbacteria,sterilization mechanism,amino fullerene
更新于2025-09-11 14:15:04
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A fluorescence quenching based gene assay for Escherichia coli O157:H7 using graphene quantum dots and gold nanoparticles
摘要： A fluorometric assay is described for highly sensitive quantification of Escherichia coli O157:H7. Reporter oligos were immobilized on graphene quantum dots (GQDs), and quencher oligos were immobilized on gold nanoparticles (AuNPs). Target DNA was co-hybridized with reporter oligos on the GQDs and quencher oligos on AuNPs. This triggers quenching of fluorescence (with excitation/emission peaks at 400 nm/530 nm). On introducing target into the system, fluorescence is quenched by up to 95% by 100 nM concentrations of target oligos having 20 bp. The response to the fliC gene of E. coli O157:H7 increases with the logarithm of the concentration in the range from 0.1 nM to 150 nM. The limit of detection is 1.1 ± 0.6 nM for n = 3. The selectivity and specificity of the assay was confirmed by evaluating the various oligos sequences and PCR product (fliC gene) amplified from genomic DNA of the food samples spiked with E. coli O157:H7.
关键词： Food pathogens,Static quenching,fliC gene,Selectivity,Fluorophore,Quencher,Real samples
更新于2025-09-11 14:15:04
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Optimization of ultrafast laser parameters for 3D micromachining of fused silica
摘要： We present an optimization study on laser parameters for 3D micromachining of fused silica to achieve critical goals for practical applications including high surface quality, high volume production, and complex surfaces by ultrafast laser direct writing assisted chemical etching. We conducted experiments on laser pulse width of 300 fs and 1 ps, pulse energy ranging from 0.1 μJ to 1.6 μJ, three different polarizations (circular, parallel and perpendicular) and number of overlapped pulses from 3 to 10,000 at 1030 nm with up to 2 MHz repetition rate to investigate their effect on nanogratings and one dimensional (1D) channel and two dimensional (2D) planar surface selective etching on 1 mm thick fused silica. In one configuration, we achieved 21.8 nm RMS surface roughness with 80 μm Gaussian filtering and in another configuration, we estimated the maximum writing speed to be 1.25 m/s for given 2 MHz repetition rate with less than 400 nm filtered root mean square (RMS) surface roughness at a 1 mm2 area which covers the thickness of the glass.
关键词： 3D microfabrication,Direct writing,Roughness,Chemical etching,Selectivity,Ultrafast laser
更新于2025-09-11 14:15:04
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Role of Spectral Line Profile in Laser IR Analysis of Multicomponent Gas Mixtures
摘要： Topical issues of the quantitative analysis of multicomponent gas mixtures with use of laser absorption infrared technologies are addressed. It is shown that a number of questions exist regarding the detection of pollutants using these technologies, and these concern not only the position of the center of the analytical line of the detected substance but also the shape of its profile, especially in case of strong intermolecular interactions under conditions of open atmosphere. A number of examples show various aspects of the influence of the error of the spectroscopic model embedded in the solution of the inverse problem (the width and shape of the laser spectral line and gas absorption lines) on the determination of gas concentrations. The parameters of the sensitivity and selectivity of laser gas analysis that support making the optimal choice of laser radiation frequencies for studying specific gas mixtures are discussed. The importance of the high monochromaticity of laser lines, the smooth tuning of the radiation frequency over a wide spectral range, and the adequate simulation of the IR spectra of multicomponent gas mixtures are demonstrated.
关键词： multicomponent gas mixture,absorption line shape,intensity,quantitative laser analysis,sensitivity,model IR spectra,simulation parameters,selectivity
更新于2025-09-11 14:15:04
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Detection of IL-8 in human serum using surface-enhanced Raman scattering coupled with highly-branched gold nanoparticles and gold nanocages
摘要： Mesoporous materials are ideal carriers for guest molecules and they have been widely used in analytical science. The unique mesoporous structure provides special properties including large specific surface area, tunable pore size, and excellent pore connectivity. The structural properties of mesoporous materials have been largely made use of to improve the performance of analytical methods. For instance, the large specific surface area of mesoporous materials can provide abundant active sites and increase the probability of contact between analytes and active sites to produce stronger signals, thus leading to the improvement of detection sensitivity. The connections between analytical performances and the structural properties of mesoporous materials have not been discussed previously. Understanding the "structure–performance relationship" is highly important for the development of analytical methods with excellent performance based on mesoporous materials. In this review, we discuss the structural properties of mesoporous materials that can be optimized to improve the analytical performance. The discussion is divided into five sections according to the analytical performances: (i) selectivity-related structural properties, (ii) sensitivity-related structural properties, (iii) response time-related structural properties, (iv) stability-related structural properties, and (v) recovery time-related structural properties.
关键词： analytical science,stability,recovery time,response time,structure–performance relationships,selectivity,sensitivity,mesoporous materials
更新于2025-09-11 14:15:04
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Multiwalled carbon nanotube based aromatic volatile organic compound sensor: sensitivity enhancement through 1-hexadecanethiol functionalisation
摘要： Aromatic volatile organic compound (VOC) sensors are attracting growing interest as a response to the pressing market need for sensitive, fast response, low power consumption and stable sensors. Benzene and toluene detection is subject to several potential applications such as air monitoring in chemical industries or even biosensing of human breath. In this work, we report the fabrication of a room temperature toluene and benzene sensor based on multiwall carbon nanotubes (MWCNTs) decorated with gold nanoparticles and functionalised with a long-chain thiol self-assembled monolayer, 1-hexadecanethiol (HDT). High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) were performed to characterize the gold nanoparticle decoration and to examine the thiol monolayer bonding to the MWCNTs. The detection of aromatic vapours using Au-MWCNT and HDT/Au-MWCNT sensors down to the ppm range shows that the presence of the self-assembled layer increases the sensitivity (up to 17 times), selectivity and improves the response dynamics of the sensors.
关键词： multiwall carbon nanotubes (MWCNTs),vapour sensor,sensitivity,gold-decorated MWCNTs,self-assembled monolayers (SAMs),selectivity
更新于2025-09-11 14:15:04
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Ruthenium decorated tungsten disulfide quantum dots for CO2 gas sensor
摘要： In this work, a selective chemi-resistive gas sensor for carbon dioxide gas detection at room temperature (~ 25 °C) was successfully fabricated, where ruthenium decorated tungsten disulfide (Ru@WS2) quantum dots (QDs) have been used as the sensing material. A mixed solvent of lithium hydroxide (LiOH·H2O) and N-Methyl-2-pyrrolidone (NMP) were used to obtain the Ru decorated WS2 QD from the exfoliated WS2 nanoflakes. Then the prepared WS2 QD and Ru@WS2 QD were confirmed using different material characterisation techniques. The gas sensors were then exposed to various concentration of CO2 gas in dry air condition. Also, the effect of humidity of both the sensors in 5000 ppm CO2 gas has been studied. The Ru@WS2 QDs based sensor showed superior sensitivity and good selectivity to CO2 gas in comparison with isopropanol, acetone, ethanol, methanol and benzene at room temperature than WS2 QD. The sensor showed an increase in resistance when exposed to CO2 gas ranging from 500 to 5000 ppm, indicating p-type characteristics. Ru@WS2 QD shows less effect at different humid condition compares to WS2 QD as a CO2 gas sensor.
关键词： Ruthenium decorated tungsten disulfide (Ru@WS2),Transition metal dichalcogenides (TMDC),Quantum Dot (QD),Sensitivity,Selectivity,Gas sensor
更新于2025-09-11 14:15:04
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High selectivity band‐stop filters using coaxial‐fed substrate integrated waveguide
摘要： A novel band-stop filter (BSF) using coaxial-fed slotted substrate integrated waveguide (SIW) is proposed in this article. The proposed BSF is designed using coaxial-fed line with extended probes penetrating through the substrate and connecting each other, instead of using the main transmission line to dispose the resonators. The SIW cavities perform the resonators excited by the probes to produce a stopband. Then, two BSFs with one and two SIW cavities are firstly designed, both of them have SIW cavity resonator modes and lower-band reflection zeroes. Then, two types of third-order BSFs using two cavity resonators and one slot resonator are presented, the high selectivity is achieved by the RZs at both sides of the stopband. Finally, one of the proposed third-order BSFs is fabricated and measured to verify the design method.
关键词： substrate,high,coaxial-fed,waveguide (SIW),band-stop,integrated,selectivity
更新于2025-09-11 14:15:04
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Gas Sensing Performances of ZnO Hierarchical Structures for Detecting Dissolved Gases in Transformer Oil: A Mini Review
摘要： Power transformer is one of the critical and expensive apparatus in high voltage power system. Hence, using highly efficient gas sensors to real-time monitor the fault characteristic gases dissolved in transformer oil is in pressing need to ensure the smooth functionalization of the power system. Till date, as a semiconductor metal oxide, zinc oxide (ZnO) is considered as the promising resistive-type gas sensing material. However, the elevated operating temperature, slow response, poor selectivity and stability limit its extensive applications in the field of dissolved gases monitoring. In this respect, rigorous efforts have been made to offset the above-mentioned shortcomings by multiple strategies. In this review, we first introduce the various ZnO hierarchical structures which possess high surface areas and less aggregation, as well as their corresponding gas sensing performances. Then, the primary parameters (sensitivity, selectivity and stability) which affect the performances of ZnO hierarchical structures based gas sensors are discussed in detail. Much more attention is particularly paid to the improvement strategies of enhancing these parameters, mainly including surface modification, additive doping and ultraviolet (UV) light activation. We finally review gas sensing mechanism of ZnO hierarchical structure based gas sensor. Such a detailed study may open up an avenue to fabricate sensor which achieve high sensitivity, good selectivity and long-term stability, making it a promising candidate for transformer oil monitor.
关键词： ZnO,sensitivity,gas sensors,hierarchical structures,stability,gas sensing mechanism,selectivity
更新于2025-09-10 09:29:36
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A Bifunctional Luminescent Coordination Polymer as Recyclable Sensor for Detecting TNP and Fe3+ with High Selectivity and Sensitivity
摘要： A thermo-stable three dimensional network [Cd2(BPDPE)2(1,2-H2bdc)2]n (1) (1,2-H2bdc = 1,2-benzenedicarboxylic acid, BPDPE = 4,4′-bis(pyridyl)diphenyl ether) with blue fluorescence was successfully synthesized and characterized. Complex 1 is a two-dimensional layer constructed by BPDPE connecting [Cd(1,2-bdc)]n one-dimensional chains, then a three-dimensional network is finally formed via π···π interactions. Importantly, Complex 1 presents an excellent fluorescent MOF sensor for highly sensitive and selective detecting TNP, the Ksv is up to 1.03×105 M-1. Further more, complex 1 can be quickly regenerated by simple washing, exhibiting good recyclability for detecting TNP. In addition, complex 1 shows higher sensitive fluorescent sensor for detecting Fe3+ cation than other metal ions. the Ksv is calculated to be 1.84×105 M-1. Furthermore, the quenching mechanisms of complex 1 as bifunctional sensor were studied as well.
关键词： Nitro aromatic explosives,Selectivity and sensitivity,Fluorescence sensing,Metal ions,Coordination polymer
更新于2025-09-10 09:29:36