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Determination of Nitrogen Concentration in Fresh Pear Leaves by Visible/Near-Infrared Reflectance Spectroscopy
摘要： A rapid and reliable method is required to determine the N status of pear (Pyrus communis L.) leaves during the growing season for timely fertilization to improve the yields and fruit quality. In the present study, we evaluated visible and near-infrared reflectance (Vis/NIR) spectra of fresh pear leaves using partial least squares (PLS) regression to determine the N concentration of fresh pear leaves. In addition, we studied the performance of modified spectra generated using different preprocessing techniques. A total of 450 leaf samples were collected from 6-yr-old pear trees of two cultivars, and randomly separated into two subsets (calibration subset [294 samples] and validation subset [180 samples]) after excluding outliers by using principle component analysis. Results showed that the model built using full spectra performed better than that developed using characteristic wavelength segments. In addition, we found that original spectral proved to provide better accuracy than derivative spectra. Among the studied preprocessing techniques, moving average smoothing (MAS) technique improved accuracy the most. Overall results suggested that PLS regression with preprocessing of full spectra using MAS is optimal method for modeling N concentration of fresh pear leaves which yielded 0.961 and 0.953 coefficient of determination (R2) for calibration and cross-validation, respectively. The validation of this method resulted high R2 value (0.847) and low mean relative error (4.48%). In conclusion, this model could provide a rapid and more reliable method to determine the total N concentration in fresh pear leaves and could be useful for fertilization management in pear orchards.
关键词： partial least squares regression,preprocessing techniques,pear leaves,Nitrogen concentration,visible/near-infrared reflectance spectroscopy
更新于2025-09-09 09:28:46
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Novel photocatalyst nitrogen-doped simonkolleite Zn5(OH)8Cl2·H2O with vis-up-conversion photoluminescence and effective visible-light photocatalysis
摘要： As photocatalysts exhibit selectivity toward various pollutants, it is necessary to develop different and novel photocatalysts. In this work, a novel photocatalyst-nitrogen-doped simonkolleite Zn5(OH)8Cl2·H2O (DSM) is prepared through a new facile method: calcinating the mixture of zinc hydroxide, urea, and guanidine hydrochloride at 575?°C for 1?h in a furnace with an air atmosphere. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, UV–visble near-infrared diffuse reflection spectra (UV–Vis–NIR DRS), Brunauer–Emmett–Teller (BET) method, Ramen spectra and Zeta potential measurement, photocatalytic properties, as well as active species trapping experiments. XRD and XPS show the as-prepared powder is nitrogen-doped simonkolleite Zn5(OH)8Cl2H2O (DSM) with a small ZnCl2 fraction. SEM investigation indicates that the as-prepared powder possesses a flower-like layered shape. The UV–Vis–NIR exhibits that after doping, the DSM possesses strong light absorption in the ranges of 300–500 and 1400–2500?nm, a direct electronic transition with a band gap energy of 2.469?eV. PL measurement reveals a strong photoluminescence and an up-conversion from lower to higher-energy visible light in as-prepared samples. Zeta potential investigations show that during photocatalysis, the charges on as-prepared photocatalyst are positive. The photocatalytic experiments show a good dark adsorption, a high photodegradation (99.4% at 60?min), a high pseudo-first-order constant (k) of 0.0261?min?1. Meanwhile, the active species trapping experiments suggest that hole (h+) is the dominant active species during photocatalysis. It is concluded that the doping favors in enhancing vis-light-photocatalysis. This work makes a significant contribution to the literature.
关键词： photocatalyst,nitrogen-doped simonkolleite,visible-light photocatalysis,photoluminescence
更新于2025-09-09 09:28:46
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Fluorescence-based analyser as a rapid tool for determining soluble protein content in dairy ingredients and infant milk formula
摘要： Milk protein, in particular native whey protein, is of interest to dairy manufacturers as a measure of functional and nutritional quality. However, quantification of soluble whey protein (SP) is time consuming; giving rise to the need to develop rapid, accurate, and portable at-line process analytical technology. In this study, the performance of a fluorescence-based analyser(F) (Amaltheys II, Spectralys Innovations, France) was evaluated for quantification of SPF and whey protein nitrogen index (WPNI)F in skim milk, whey protein concentrate and infant formula powders. Rehydration of powders prior to analysis was a key factor for ensuring repeatability and reproducibility. A comparison of the analyser with reference methods for SPF and WPNIF resulted in coefficient of determination (R2) > 0.993 for both SPKjeldahl method and WPNIGEA. The results show the fluorescence-based analyser to be rapid, compact, and accurate device, suited for providing reliable support to dairy ingredient and infant formula manufacturers.
关键词： Infant milk formula,Process analytical technology,Dairy ingredients,Whey protein nitrogen index,Soluble protein,fluorescence-based analyser
更新于2025-09-09 09:28:46
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Noise spectroscopy of a quantum-classical environment with a diamond qubit
摘要： Knowing a quantum system’s environment is critical for its practical use as a quantum device. Qubit sensors can reconstruct the noise spectral density of a classical bath, provided long enough coherence time. Here, we present a protocol that can unravel the characteristics of a more complex environment, comprising both unknown coherently coupled quantum systems, and a larger quantum bath that can be modeled as a classical stochastic field. We exploit the rich environment of a nitrogen-vacancy center in diamond, tuning the environment behavior with a bias magnetic field, to experimentally demonstrate our method. We show how to reconstruct the noise spectral density even when limited by relatively short coherence times, and identify the local spin environment. Importantly, we demonstrate that the reconstructed model can have predictive power, describing the spin qubit dynamics under control sequences not used for noise spectroscopy, a feature critical for building robust quantum devices. At lower bias fields, where the effects of the quantum nature of the bath are more pronounced, we find that more than a single classical noise model are needed to properly describe the spin coherence under different controls, due to the back action of the qubit onto the bath.
关键词： nitrogen-vacancy center,diamond qubit,noise spectroscopy,dynamical decoupling,quantum-classical environment
更新于2025-09-09 09:28:46
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Combined adsorption process and photocatalytic degradation of some commercial herbicides over N-doped TiO <sub/>2</sub> particles supported on recyclable magnetic hexagonal mesoporous silica
摘要： Magnetic hexagonal mesoporous silica (magnetic HMS) containing N-doped TiO2 was prepared by hydrothermal method and used for the removal of trifluralin, 2,4-dichlorophenoxyacetic acid, and glyphosate herbicides at the presence and absence of UV/visible lights. The prepared samples were found as efficient for the removal of the herbicides and easily recyclable after treatment by UV irradiation. A red shift effect by nitrogen doping was also observed in the prepared samples resulting photocatalytic activity at the presence of visible light. Kinetic studies indicated that the photodegradation followed as the first order and kUV ≈ 10kvis. The results also showed synergetic effects between the adsorption of herbicides on the surface of magnetic HMS and photoreactions over N-doped TiO2 species.
关键词： nitrogen doping,titanium oxide,herbicide,HMS,Photocatalyst
更新于2025-09-09 09:28:46
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UV–vis spectroscopy combined with azastilbene probe as a tool for testing basicity of mesoporous silica modified with nitrogen compounds
摘要： N-bromobenzyl substituted (E)-4′-hydroxy-4-stilbazolium bromide (NBSB), a representative of azastilbene compounds which reveals strong solvatochromism, was used as a probe molecule for testing basicity of nitrogen organic compounds grafted on mesoporous cellular foam silica (MCF). Easy deprotonation of this compound in contact with basic species was the reason for its use for probing the basicity of AP/MCF (AP - (3-aminopropyl) trimethoxysilane), Im/MCF (Im - N-trimethoxysililpropylimidazole) and Az/MCF (Az - (3-azidopropyl)(triethoxy)silane). NBSB and its deprotonated form were analyzed by UV–vis spectroscopy measurements in solutions and UV–vis in solid materials. Ab-initio calculation allowed distinction between the preference of NBSB for interactions with SiOH on the support surface and with nitrogen species of the modi?er. The NBSB protonation - deprotonation equilibrium dependence on pH was indicated. The role of solvent was considered. In water indirect probing of basicity by NBSB was observed via abstraction of proton from solvent by the modi?er and deprotonation of NBSB due to the increased pH of the solution. In acetonitrile direct basicity probing took place in which NBSB was adsorbed in MCF pores. AP/MCF and Im/MCF caused deprotonation of NBSB, as monitored by UV–vis re?ectance spectra. This e?ect was stronger for AP/MCF, which showed higher basicity. Az/MCF could not deprotonate NBSB in either water or acetonitrile.
关键词： Basicity,FTIR,Ab-initio calculations,Hydroxystilbazolium cyanines,UV–vis,Nitrogen compounds on MCF
更新于2025-09-04 15:30:14
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Fabrication of large surface area nitrogen vacancy modified graphitic carbon nitride with improved visible-light photocatalytic performance
摘要： In this work, nitrogen vacancy modified graphitic carbon nitride (g-C3N4) with large surface area was synthesized and analyzed by a series of instruments, including XRD, FTIR, XPS, EPR SEM, TEM, DRS and PL, etc. and the photocatalytic H2-evolution activity was investigated. The results indicated that the as-synthesized g-C3N4 with nitrogen vacancy exhibited stronger visible light response capability, enlarged specific surface area and notably separated rate of photoinduced charge carriers, which caused the as-synthesized photocatalyst possessing the higher hydrogen evolution rate (5250 μmol h?1 g?1) and excellent recycle stability. Evidently, this work could provide a new insight for preparing highly efficient photocatalyst.
关键词： Large surface area,Nitrogen vacancy,Photocatalysis,g-C3N4,Photocatalytic performance
更新于2025-09-04 15:30:14
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ZnO-coated SiO2 nanocatalyst preparation and its photocatalytic activity over nitric oxides as an alternative material to pure ZnO
摘要： Core-shell nanospheres, CSNp, consisting of silica as a core and zinc oxide as a shell were prepared via a simple and environmentally friendly procedure. Silica cores with a mean diameter of 300 nm were prepared through the hydrolysis-condensation reactions in the presence of hyperbranched poly(ethylene)imine (HBPEI) followed by calcination and chemical surface modi?cation with the use of HBPEI. To fabricate the core-shell structure, various amounts of zinc nitrate hexahydrate were precipitated using the carboxymethyl poly(ethylene)imine polymer (Trilon P) as a precipitator. To this suspension, the as synthesized modi?ed silica powder was added with the aim to develop electrostatic bonds between the carboxyl groups of TRILON P and the amino groups of the cationic HBPEI polymer. The optimization of processing parameters led to the development of homogeneous core-shell structures bearing a well-developed nanocrystalline zinc oxide shell over each silica core. The material with the optimum shell showed excellent photocatalytic activity over nitric oxides as the photocatalytic yield reached 72.9%.
关键词： Core-shell,Photocatalysis,Silicon oxide,Nitrogen oxides,Zinc oxide
更新于2025-09-04 15:30:14
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Nitrogen passivation formation on Cu surface by Ar–N2 plasma for Cu-to-Cu wafer stacking application
摘要： Wafer stacking technology provides reduced interconnect delay, improved bandwidth, reduced form factor, and decreased cost. Solder-based metallic die bonding is presently utilized in high-volume manufacturing, but Cu-based metallic wafer bonding is quickly becoming a key bonding technique for next generation 3D IC and heterogeneous stacking applications. In this study, Ar–N2 plasma treatment on Cu surface was investigated to passivate Cu surface with nitrogen and to enhance the bonding quality of Cu-to-Cu wafer bonding. The Ar–N2 plasma treatment was performed by conventional DC sputtering under 5 mTorr working pressure with different Ar–N2 partial pressures. Then, the effect of Ar–N2 plasma treatment on Cu surface was evaluated structurally and electrically. It was observed that the Ar–N2 plasma treatment with high nitrogen partial pressure over a sufficient plasma treatment time provided activated Cu surface, reduction of copper oxide and chemisorbed nitrogen, and copper nitride passivation. The Ar–N2 plasma treatment of Cu surface was found to be a potential pretreatment method for Cu-to-Cu bonding.
关键词： Nitrogen passivation,3D IC,Wafer stacking,Cu-to-Cu bonding,Ar–N2 plasma treatment
更新于2025-09-04 15:30:14
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Enhanced Visible Light Sensitization of N-doped TiO2 Nanotubes Containing Ti-Oxynitride Species Fabricated via Electrochemical Anodization of Titanium Nitride
摘要： The concentration and chemical state of nitrogen represent critical factors to control the band-gap narrowing and the enhancement of visible light harvesting in nitrogen-doped titanium dioxide. In this study, photocatalytic TiO2-N nanoporous structures were fabricated by the electrochemical anodization of titanium nitride sputtered films. Doping was straightforwardly obtained by oxidizing as-sputtered titanium nitride films containing N-metal bonds varying from 7.3 to 18.5 % in the Ti matrix. Severe morphological variations into the as-anodized substrates were registered at different nitrogen concentration and studied by Small-Angle X-ray Scattering. Titanium nitride films with minimum N content of 6.2 at% N led to a quasi-nanotubular geometry, whilst an increase in N concentration up to 23.8 at% determined an inhomogeneous, polydispersed distribution of nanotube apertures. The chemical state of nitrogen in the TiO2 matrix was investigated by X-ray Photoelectron Spectroscopy depth profile analysis and correlated to the photocatalytic performance. The presence of Ti-N and β-Ti substitutional bonds, as well as Ti-oxynitride species was revealed by the analysis of N 1s X-ray Photoelectron Spectroscopy High Resolution spectra. The minimum N content of 4.1 at% in the TiO2-N corresponded to the lowest Ti-oxynitride ratio of 13.5 %. The relative variation of N-metal bonds was correlated to the visible light sensitization and the highest Ti-N/Ti oxynitride ratio of 3.3 was attributed to the lowest band-gap of 2.7 eV and associated to a threefold increase in the degradation of organic dye. Further increase of N doping led to a dramatic drop of Ti-N/Ti oxynitride ratio, from 3.3 to 0.4, which resulted in a loss photocatalytic activity. The impact of the chemical state of nitrogen towards efficient doping of TiO2 nanotubes is demonstrated with a direct correlation to the N loading and a strategy to optimise these factors based on a simple, rapid synthesis from titanium nitride.
关键词： visible light sensitization,photocatalytic performance,titanium nitride,nitrogen-doped titanium dioxide,electrochemical anodization
更新于2025-09-04 15:30:14