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Optical Chirality Sensing with an Auxiliary-free Earth-abundant Cobalt Probe
摘要： Broadly useful chiroptical ee sensing remains challenging and typically involves carefully designed molecular receptors or supramolecular assemblies. Herein, we describe enantioselective sensing of 35 amino acids, amino phosphonic acids, hydroxy acids, amino alcohols and diamines with an auxiliary-free cobalt probe. Chiroptical analysis of the enantiomeric composition and concentration of minute sample amounts is achieved with high accuracy using earth-abundant cobalt salts and hydrogen peroxide as oxidant. Despite the absence of an auxiliary ligand, the cobalt assay is applicable to aromatic and aliphatic compounds and yields strong CD signals at high wavelengths. This method eliminates the general prerequisite for chromophoric metal ligands to generate chiroptical signals via ECCD effects or through analyte-to-ligand chirality induction, and it offers operational simplicity, cost-efficiency, waste reduction and speed.
关键词： ee determination,concentration analysis,Werner complexes,Chirality sensing,chiroptical spectroscopy
更新于2025-09-10 09:29:36
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Colorimetric Determination of Hypochlorite Based on the Oxidative Leaching of Gold Nanorods
摘要： Hypochlorite plays a critical role in killing microorganisms in the water. However, it can also cause cardiovascular diseases, neuron degeneration, and cancer to humans. Although traditional methods feature excellent sensitivity and reliability in detecting hypochlorite, the expensive instruments and strict determination conditions have limited their application in environmental analysis to some extent. Thus, it is necessary and urgent to propose a cheap, facile, and quick analytical assay for hypochlorite. This paper proposes a colorimetric assay for hypochlorite utilizing gold nanorods (AuNRs) as the nanoreactor and color reader. The AuNRs were acquired via a reported seed-mediated method. NaClO with strong oxidation property can cause the etching of gold from the longitudinal tips of AuNRs, which could shorten the aspect ratio of AuNRs, decrease the absorption in the UV–Vis spectrum and also induce the solution color changing from red to pale yellow. Thus, according to the solution color change and the absorbance of longitudinal surface plasmon resonance of AuNRs, we established the calibration curve of NaClO within 0.08 μM to 125 μM (?Abs = 0.0547 + 0.004 CNaClO, R2 = 0.9631). Compared to traditional method, we obtained the conversion formula between the concentration of residual-chlorine in tap water and the concentration of hypochlorite detected by the proposed colorimetric assay, which is Cresidual-chlorine = 0.24 CNaClO. Finally, the real application of the colorimetric assay in tap water was successfully performed, and the accuracy of the colorimetric method can reach from ?6.78% to +8.53%.
关键词： colorimetric determination,hypochlorite,gold nanorod
更新于2025-09-10 09:29:36
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Surface Molecularly Imprinted Carbon Dots Based Core-Shell Material for Selective Fluorescence Sensing of Ketoprofen
摘要： In this work, we report an environment friendly core-shell material based on Carbon Dot core and Molecularly Imprinted Polymer shell as sensor for highly selective fluorescence detection of ketoprofen. The Carbon Dots (CDs) were prepared by a hydrothermal method and the polymer layer around the CDs core was synthesised by sol-gel polymerisation. The prepared material was characterized by Fluorescence Spectroscopy, FT-IR Spectroscopy and Transmission Electron Spectroscopy (TEM). Fluorescence from the Carbon Dots- Molecularly Imprinted Polymer (CDs-MIP) was found to quench selectively in the presence of ketoprofen and quenching effect was found to be greater than for Non-Imprinted Polymer (CDs-NIP) which indicated the potential of CDs-MIP as a fluorescence sensing material for ketoprofen. The imprinting factor was obtained to be 2.35. Under optimized conditions, a linear response was obtained in the concentration range from 0.039 to 3.9 μM with a detection limit of 0.01 μM. The correlation coefficient was 0.999. The developed sensor was applied to determination of ketoprofen in human serum and urine samples with good recoveries ranging from 96 to 104% indicating successful application of the proposed sensor in biological fluids.
关键词： Molecularly imprinted polymer,Fluorescence determination,Carbon dots,Ketoprofen
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Multiple Chinese Vehicle License Plate Localization in Complex Scenes
摘要： License plate localization is an essential part of automated vehicle license plate recognition (ALPR). This paper proposes a two-step approach of the vehicle license plate (LP) localization which includes a novel attempt for LP detection and a new method for LP skew correction. The proposed approach begins with detecting the LP region while classifying the LP type in the image using single shot multi-box detector (SSD) and then further precisely determining the LP corner points in detected region by fitting LP borderlines according to the character contours based on the multi-level thresholding binarization. The experiment evaluated the performance of the proposed method on 600 vehicle images (~800(cid:13)(cid:13)800) captured under realistic complex environment. The result shows that LPs in 579 images can be localized exactly (96.5% accuracy) and processing speed is up to 27 FPS on average.
关键词： single shot multi-box detection,license plate corner points determination,vehicle license plate localization
更新于2025-09-10 09:29:36
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Orbit Determination of Korean GEO Satellite Using Single SLR Sensor
摘要： Geostationary Earth Orbit (GEO)-Korea Multi-Purpose Satellite (KOMPSAT)-2B (GK-2B) is a Korean geostationary Earth orbit (GEO) satellite that is scheduled to be launched in 2020 for meteorological and ocean monitoring. While the primary orbit determination (OD) for GK-2B is by ground-based radar observations and the expected orbit precision is less than 1 km, a satellite laser ranging (SLR) technique has been selected as a subsidiary OD method to verify/complement/enhance primary OD results. In general, the available time and equipment for observing GEO satellites with SLR are limited. Furthermore, because the optical sensors mounted on GK-2B may be defected by laser, only a domestic single SLR station would obtain the tracking data. This research presents the mitigation of these drawbacks to improve orbit precision. Observation data generation and the associated OD of GK-2B are performed by considering numerical SLR data analysis on Compass-G1, a Chinese GEO navigation satellite, and Chinese SLR station at Changchun. With the OD performed for two scenarios with the varying number of observations, the 3D position error is 24.01 m when 13 observations per day are obtained, while the error becomes 43.46 m when 9 observations per day are obtained. To verify these results, the OD of Compass-G1 using actual SLR data from Changchun station is performed to yield 31.89 m for 3D error, which is favorable compared with the external precise ephemeris by GeoForschungsZentrum (GFZ) analysis center. Therefore, the OD based on single SLR station is applicable to estimating the orbit within less than 100 m.
关键词： orbit determination (OD),satellite laser ranging (SLR),GK-2B,Compass-G1,geostationary Earth orbit (GEO)
更新于2025-09-10 09:29:36
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Automated and observer based light field indicator edge evaluation in diagnostic X-ray equipment
摘要： Introduction: To analyze edge detection and optical contrast calculation of light field-indicators used in X-ray via automated- and observer-based methods, and comparison with current standard approaches, which do not give exact definition for light field edge determination. Methods: Automated light sensor array was used to measure the penumbra zone of the edge in the standard X-ray equipment, while trained and na?ve human observers were asked to mark the light field edge according to their own determination. Different interpretations of the contrast were then calculated and compared. Results: In contrast to automated measurements of edge definition and detection, measurements by human observers showed large inter-observer variation independent of their training with X-ray equipment. Different contrast calculations considering the different edge definitions gave very different contrast values. Conclusion: As the main conclusion, we propose a more exact edge definition of the X-ray light field, corresponding well to the average human observer’s edge determination. The new edge definition method with automated systems would reduce human variability in edge determination. Such errors could potentially affect the approval of X-ray equipment, and also increase the radiation dose. The automated measurement based on human observers’ edge definition and the corresponding contrast calculation may lead to a more precise light field calibration, which enables reduced irradiation doses on radiology patients.
关键词： X-ray equipment type test,Radiation protection,Edge determination,Light field indicator,Diagnostic X-ray
更新于2025-09-10 09:29:36
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Color-tunable particles through affinity interactions between water-insoluble protein and soluble dyes
摘要： This research is focused on the delivery of color using zein particles as a carrier and contributes to understanding the interactions between colorants and zein. Co-precipitation of purified zein protein with anionic dyes such as sulfonate group containing azo-dyes (patent blue sodium salt, azorubine, and fast green FCF) are used to prepare red, green, and blue colored nanoparticles. These dyes had electrostatic interactions with zein and they remained bound in the zein particles even after dialysis. This was not the case for purpurin, for with hydrogen bonding was expected as interaction. Upon increasing dye concentration, the particle sizes increased as a result of a change in the kinetics of precipitation, which was affected by the association between zein and the dye. However, the encapsulation efficiency continued to be very high and no plateau was reached for the used concentrations. The post-addition of dye on undyed zein particles was used to confirm that there is indeed a high affinity between the dye and the protein. The amount of free dye was determined and the affinity was again found to be high (dye adsorption ?95%). The amount of dye incorporated into the particles and the resulting color were similar using both techniques. These results show that there is a high affinity between the zein protein and the dye, and may be exploited to produce bio-based and optically-functionalized nanoparticles using zein as a carrier.
关键词： Zein,dye,color determination,interaction,co-precipitation
更新于2025-09-10 09:29:36
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Improvement of the surface shape error of the pitch lap to a deterministic continuous polishing process
摘要： Continuous polishing using pitch lap is a key process in ?nishing large ?at optical elements. The ?gure of the optics is primarily dependent on the surface shape of the pitch lap. In this study, a novel method is proposed to determine the lap shape error by rotating the lap while the measurement point is moved radially using a precision slide mechanism. The systematic measuring error including the slide straightness error and slide perpendicularity error with respect to the lap rotary axis is divided into 1) the straightness and absolute horizontality error of the slide and 2) the absolute verticality error of the lap rotary axis. It is proposed that the former can be determined using a displacement sensor to measure water surface while moving along the slide, while the latter can be determined by an electric gradienter placed on the rotating lap. Furthermore, a small heating tool is proposed for correcting the local surface shape error of the pitch lap considering its viscoelastic property, and thus obtaining a favorable shape on the entire surface by controlling the dwell time of the small tool. Our experiments validated that the surface shape error of the pitch lap can be corrected by the method signi?cantly, and that the optic ?gure is signi?cantly promoted.
关键词： Determination and correction,Lap surface shape,Continuous polishing
更新于2025-09-09 09:28:46
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Development of a micelle-enhanced high-throughput fluorometric method for determination of niclosamide using a microplate reader
摘要： The present paper describes the development and validation of a simple and sensitive micelle‐enhanced high‐throughput fluorometric method for the determination of niclosamide (NIC) in 96‐microwell plates. The proposed method is based on the reduction of the nitro group of niclosamide to an amino group using Zn/HCl to give a highly fluorescent derivative that was developed simultaneously and measured at λem 444 nm after excitation at λex 275 nm. Tween‐80 and carboxymethylcellulose (CMC) have been used as fluorescence enhancers and greatly enhanced the fluorescence by factors of 100–150%. The different experimental conditions affecting the fluorescence reaction were carefully investigated and optimized. The proposed method showed good linearity (r2≥ 0.9997) over the concentration ranges of 1–5 and 0.5–5 μg/ml with lower detection limits of 0.01 and 0.008 μg/ml and lower quantification limits of 0.04 and 0.03 μg/ml on using Tween‐80 and or CMC, respectively. The developed high‐throughput method was successfully applied for the determination of niclosamide in both tablets and spiked plasma. The capability of the method for measuring microvolume samples made it convenient for handling a very large number of samples simultaneously. In addition, it is considered an environmentally friendly method with lower consumption of chemicals and solvents.
关键词： high‐throughput method,microplate reader,fluorescence,niclosamide determination
更新于2025-09-09 09:28:46
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Same Magic Number but Different Arrangement: Alkynyl-Protected Au25 with D3 Symmetry Jiao-Jiao Li, Zong-Jie Guan, Zhen Lei, Feng Hu, and Quan-Ming Wang*
摘要： We synthesize two homoleptic alkynyl-protected gold clusters Na[Au25(C≡CAr)18] and (Ph4P)[Au25(C≡CAr)18] (Ar = 3,5-bis(trifluoromethyl)phenyl) via direct reduction method. 1 is a magic cluster analogous to [Au25(SR)18]- in terms of electron counts and metal-to-ligand ratio. Single crystal structure analysis reveals that 1 has identical Au13 kernel to [Au25(SR)18]-, but adopts distinctly different arrangement of the six peripheral dimer staple motifs. The steric hindrance of alkynyl ligands is responsible for the D3 arrangement of Au25. The introduction of alkynyl also significantly changes the optical absorption features of the nanocluster as supported by DFT calculations. This magic cluster confirms that there is a similar but quite different parallel alkynyl-protected metal cluster universe in comparison to the thiolated one.
关键词： optical properties,gold,alkynyl ligands,cluster compounds,structure determination
更新于2025-09-09 09:28:46