Online quantitative analysis of soluble solids content in navel oranges using visible-nearinfrared spectroscopy and variable selection methods

Variable selection is applied widely for visible-near infrared(Vis-NIR)spectroscopy analysis of internal quality in fruits.Different spectral variable selection methods were compared for online quantitative analysis of soluble solids content(SSC)in navel oranges.Moving window partial least squares(MW-PLS),Monte Carlo uninformative variables elimination(MC-UVE)and wavelet transform(WT)combined with the MC-UVE method were used to select the spectral variables and develop the calibration models of online analysis of SSC in navel oranges.The performances of these methods were compared for modeling the Vis NIR data sets of navel orange samples.Results show that the WT-MC-UVE methods gave better calibration models with the higher correlation cofficient(r)of 0.89 and lower root mean square error of prediction(RMSEP)of 0.54 at 5 fruits per second.It concluded that Vis NIR spectroscopy coupled with WT-MC-UVE may be a fast and efective tool for online quantitative analysis of SSC in navel oranges.

土壤全氮田间Vis/NIR光谱测定方法研究

应用Vis/NIR光谱直接测定原始土壤属性具有重要的研究和应用价值。选取我国中部水稻土和潮土共103个土样,对比分析了两种土壤在田间环境下的湿态(Rw)和干态(Rd)光谱特征。采用相对变换光谱方法对湿态光谱进行了处理,结果表明该方法能够有效降低土壤水分的干扰和消除部分噪声,得到的变换光谱(Rn)与干态光谱在信息量和特征方面具有很高的相似度。以此建立了土壤TN的PLS回归估计模型,检验结果表明,Rn对水稻土和潮土TN的估计模型精度均高于Rw,修正判定系数分别从0.26和0.46提高到0.53和0.62。因此,相对光谱变换方法能够有效提高应用田间土壤光谱估计土壤参数的能力,建立的PLS模型可以用于测定TN含量,研究结果可作为实现田间实时分析土壤属性的工作基础。

A Concept for a Novel Test for Chemical Parity

Deviations from chemical parity (PV) were evaluated with the search for very small enantiomeric excesses in a racemate prepared from non chiral materials and were detected by means of the circular dichroism (CD). Thus, intensely light-absorbing perylenebiscarboximides were attached to axially chiral biphenyls for the amplification of CD effects by exciton interactions of the adjacent chromophores. A rapidly racemising system was applied for the exclusion of artifacts and compared with an analogous with locked chirally. A very slight enantiomeric excess was detected for the (M) enantiomer. Application of the method for other systems was suggested and relations to natural products discussed.

Spectral characteristics of banded iron formations in Singhbhum craton,eastern India:Implications for hematite deposits on Mars

Banded iron formations （BIFs） are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior （Canada） and Carajas （Brazil） have been studied by planetary scientists to trace the evolution of hematite deposits on Mars. Hematite deposits are extensively identified in Meridiani region on Mars. Many hypotheses have been proposed to decipher the mechanism for the formation of these deposits. On the basis of geomorphological and mineralogical studies, aqueous environment of deposition is found to be the most supportive mechanism for its secondary iron rich deposits. In the present study, we examined the spectral characteristics of banded iron formations of Joda and Daitari located in Singhbhum craton in eastern India to check its potentiality as an analog to the aqueous/marine environment on Mars. The prominent banding feature of banded iron formations is in the range of few millimeters to few centimeters in thickness. Fe rich bands are darker （gray） in color compared to the light reddish jaspilitic chert bands. Thin quartz veins （〈4 mm） are occasionally observed in the handspecimens of banded iron formations. Spectral investigations have been conducted in VIS/NIR region of electromagnetic spectrum in the laboratory conditions. Optimum absorption bands identified include 0.65, 0.86, 1.4 and 1.9 μm, in which 0.56 and 0.86 μm absorption bands are due to ferric iron and 1.4 and 1,9 μm bands are due to OH/H2O. To validate the mineralogical results obtained from VlS/NIR spectral radiometry, laser Raman and Fourier transform infrared spectroscopic techniques were utilized and the results were found to be similar. Goethite-hematite association in banded iron formation in Singhbhum craton suggests dehydration activity, which has altered the primary iron oxide phases into the secondary iron oxide phases. The optimum bands identified for the minerals using various spectroscopic techniques can be used as reference for similar mineral deposits on any remote area on Earth or on other hydrated planetary surfaces like Mars.

Effect of nitrogen/phosphorus concentration on algal organic matter generation of the diatom Nitzschia palea:Total indicators and spectroscopic characterization

Critical algal blooms in great lakes increase the level of algal organic matters（AOMs）,significantly altering the composition of natural organic matters（NOMs） in freshwater of lake.This study examined the AOM＇s characteristics of Nitzschia palea（N.palea）,one kind of the predominant diatom and an important biomarker of water quality in the great lakes of China,to investigate the effect of AOMs on the variation of NOMs in lakes and the process of algal energy.Excitation–emission matrix fluorescence（EEM） spectroscopy,synchronous fluorescence（SF） spectroscopy and deconvolution UV–vis（D-UV） spectroscopy were utilized to characterize AOMs to study the effects of nutrient loading on the composition change of AOMs.From results,it was revealed that the phosphorus is the limiting factor for N.palea＇s growth and the generation of both total organic carbon and amino acids but the nitrogen is more important for the generation of carbohydrates and proteins.EEM spectra revealed differences in the composition of extracellular organic matter and intracellular organic matter.Regardless of the nitrogen and phosphorus concentrations,aromatic proteins and soluble microbial products were the main components,but the nitrogen concentration had a significant impact on their composition.The SF spectra were used to study the AOMs for the first time and identified that the protein-like substances were the major component of AOMs,creating as a result of aromatic group condensation.The D-UV spectra showed carboxylic acid and esters were the main functional groups in the EOMs,with –OCH_3,–SO_2NH_2,–CN,–NH_2,–O– and –COCH_3functional groups substituting into benzene rings.

Simultaneous Raman and reflection UV/Vis absorption spectroelectrochemistry

In the present work,a new combination of Raman and ultraviolet and visible(UV/Vis)absorption spectroelectrochemistry in reflection mode is proposed.The new experimental setup allows obtaining the two kinds of spectroscopic data without interferences concomitantly with the electrochemical information.To the best of our knowledge,it is the first time to report the simultaneous obtention of electrochemical,electronic,and vibrational information in the same experiment.This new combination provides time-resolved information about the processes that are taking place on the electrode/solution interface which has significant implications in different fields of chemistry,such as modification of electrodes,studies of electrocatalytic reaction mechanisms,development of sensors,among others.Two different systems were used to demonstrate the advantages and capabilities of the brand-new technique,namely,the oxidation of potassium ferrocyanide,an out-sphere system that is usually employed in the validation of SEC techniques,and the electrochemical-surface enhanced Raman spectroscopy(EC-SERS)detection of crystal violet by in-situ formation of the silver SERS substrate,where the UV/Vis spectra were used to follow the formation of the SERS substrate,whereas the Raman response of a probe molecule was used to confirm either the formation of a nanostructured surface and to obtain the fingerprint of the molecule with a high time resolution.The brand-new experimental setup has shown to be useful,versatile,robust,compact,and easy to use for future applications.

Nondestructive perception of potato quality in actual online production based on cross-modal technology

Nowadays,China stands as the global leader in terms of potato planting area and total potato production.The rapid and nondestructive detection of the potato quality before processing is of great significance in promoting rural revitalization and augmenting farmers’income.However,existing potato quality sorting methods are primarily confined to theoretical research,and the market lacks an integrated intelligent detection system.Therefore,there is an urgent need for a post-harvest potato detection method adapted to the actual production needs.The study proposes a potato quality sorting method based on cross-modal technology.First,an industrial camera obtains image information for external quality detection.A model using the YOLOv5s algorithm to detect external green-skinned,germinated,rot and mechanical damage defects.VIS/NIR spectroscopy is used to obtain spectral information for internal quality detection.A convolutional neural network(CNN)algorithm is used to detect internal blackheart disease defects.The mean average precision(mAP)of the external detection model is 0.892 when intersection of union(IoU)=0.5.The accuracy of the internal detection model is 98.2%.The real-time dynamic defect detection rate for the final online detection system is 91.3%,and the average detection time is 350 ms per potato.In contrast to samples collected in an ideal laboratory setting for analysis,the dynamic detection results of this study are more applicable based on a real-time online working environment.It also provides a valuable reference for the subsequent online quality testing of similar agricultural products.

Selective elimination of chromophoric and fluorescent dissolved organic matter in a full-scale municipal wastewater treatment plant

Effluent organic matter（Ef OM） from municipal wastewater treatment plants potentially has a detrimental effect on both aquatic organisms and humans.This study evaluated the removal and transformation of chromophoric dissolved organic matter（CDOM） and fluorescent dissolved organic matter（FDOM） in a full-scale wastewater treatment plant under different seasons.The results showed that bio-treatment was found to be more efficient in removing bulk DOM（in term of dissolved organic carbon,DOC） than CDOM and FDOM,which was contrary to the disinfection process.CDOM and FDOM were selectively removed at various stages during the treatment.Typically,the low molecular weight fractions of CDOM and protein-like FDOM were more efficiently removed during bio-treatment process,whereas the humic-like FDOM exhibited comparable decreases in both bio-treatment and disinfection processes.Overall,the performance of the WWTP was weak in terms of CDOM and FDOM removal,resulting in enrichment of CDOM and FDOM in effluent.Moreover,the total removal of the bulk DOM（P 〈 0.05） and the protein-like FDOM（P 〈 0.05） displayed a significant seasonal variation,with higher removal efficiencies in summer,whereas removal of CDOM and the humic-like FDOM showed little differences between summer and winter.In all,the results provide useful information for understanding the fate and transformation of DOM,illustrating that sub-fractions of DOM could be selectively removed depending on treatment processes and seasonality.

Spontaneous Deposition of Uniformly Distributed Ruthenium Nanoparticles on Graphitic Carbon Nitride for Quantifying Electrochemically Accumulated H_(2)O_(2)

Highly dispersed ultrasmall ruthenium nanoparticles with a clean surface are deposited onto graphitic carbon nitride(C_(3)N_(4)-Ru)through spontaneous redox reaction between the C_(3)N_(4) sheets and Ru salt without the use of any reductant.The as-prepared C_(3)N_(4)-Ru exhibits distinct peroxidase-like activity.A nanozyme based method is successfully developed for detecting the H_(2)O_(2) generated in-situ by the two-electron oxygen reduction strategy.The C_(3)N_(4)-Ru nanozyme can realize the detection of H_(2)O_(2) with a wide linear range and a low detection limit.The testing results are also compared with the conventional modified titration method,and show greater possibility for the practical detection of H_(2)O_(2) produced via the electrochemical oxygen reduction for its higher selectivity.

Single-Component Chemical Nose with a Hemicyanine Probe for Pattern-Based Discrimination of Metal lons

We report here a chemical nose utilizing the nonspecificity of a hemicyanine dye(probe P)containing three acetates and one depro-tonatable phenol groups.Unlike conventional pattern-based recognition that requires a combination of different probes,probe P alone is able to differentiate 9 different metals,generating distinctive absorption spectra and various patterns upon principle component analysis(PCA).River water samples and commercial mineral water samples were evaluated by the probe and were successfully distinguished.

Design, Synthesis, Photophysical Studies and Electrochemistry of Carbazole-, Oxadiazole-, and Oxadiazole-Triarylamine-Containing Rhenium(Ⅰ) Diimine Alkynyl Complexes

A series of rhenium(I)diimine alkynyl complexes with various electron-and hole-transporting moieties has been synthesized and characterized.Their electronic absorption,emission and electrochemical properties have also been studied.