Nondestructive identification and classification of starch types based on multispectral techniques coupled with chemometrics.

Starch is the main source of energy and nutrition. Therefore, some merchants often illegally add cheaper starches to other types of starches or package cheaper starches as higher priced starches to raise the price. In this study, 159 samples of commercially available wheat starch, potato starch, corn starch and sweet potato starch were selected for the identification and classification based on multispectral techniques, including near-infrared (NIR), mid-infrared (MIR) and Raman spectroscopy combined with chemometrics, including pretreatment methods, characteristic wavelength selection methods and classification algorithms. The results indicate that all three spectral techniques can be used to discriminate starch types. The Raman spectroscopy demonstrated superior performance compared to that of NIR and MIR spectroscopy. The accuracy of the models after characteristic wavelength selection is generally superior to that of the full spectrum, and two-dimensional correlation spectroscopy (2D-COS) achieves better model performance than other wavelength selection methods. Among the four classification methods, convolutional neural network (CNN) exhibited the best prediction performance, achieving accuracies of 99.74 %, 97.57 % and 98.65 % in NIR, MIR and Raman spectra, respectively, without pretreatment or characteristic wavelength selection.

Sn(OTf)2-Catalyzed (3 + 2) Cycloaddition/Sulfur Rearrangement Reaction of Donor-Acceptor Cyclopropanes with Indoline-2-thiones.

The (3 + 2) cycloaddition/sulfur rearrangement reaction of donor-acceptor cyclopropanes bearing a single keto acceptor with indoline-2-thiones has been realized. Under the catalysis of Sn(OTf)2, a series of functionalized 3-indolyl-4,5-dihydrothiophenes were synthesized with moderate to excellent yields.

Photo-induced C(sp2)-H difluoroalkylation of anilines.

A photoinduced protocol for the direct difluoroalkylation of C(sp2)-H bonds in anilines under catalyst-free reaction conditions is presented. This transformation is characterized by a wide substrate scope, mild reaction conditions, and operational simplicity, and could serve as an alternative tool to established methods for the synthesis of difluoroalkylated anilines. Mechanistic studies suggest the formation of an electron-donor-acceptor (EDA) complex between anilines and difluoroalkyl bromides in this reaction.

Physiological and lipidomic response of exogenous choline chloride alleviating salt stress injury in Kentucky bluegrass (Poa pratensis).

Introduction: Choline participates in plant stress tolerance through glycine betaine (GB) and phospholipid metabolism. As a salt-sensitive turfgrass species, Kentucky bluegrass (Poa pratensis) is the main turfgrass species in cool-season areas. Methods: To improve salinity tolerance and investigate the effects of choline on the physiological and lipidomic responses of turfgrass plants under salinity stress conditions, exogenous choline chloride was applied to Kentucky bluegrass exposed to salt stress. Results: From physiological indicators, exogenous choline chloride could alleviate salt stress injury in Kentucky bluegrass. Lipid analysis showed that exogenous choline chloride under salt-stress conditions remodeled the content of phospholipids, glycolipids, and lysophospholipids. Monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lysophosphatidylcholine content were increased and phosphatidic acid content were decreased in plants after exogenous choline chloride under salt treatment. Plant leaf choline content increased, but GB was not detected in exogenous choline chloride treatment plants under nonstress or salt-stress conditions. Discussion: GB synthesis pathway related genes showed no clear change to choline chloride treatment, whereas cytidyldiphosphate-choline (CDP-choline) pathway genes were upregulated by choline chloride treatment. These results reveal that lipid remodeling through choline metabolism plays an important role in the salt tolerance mechanism of Kentucky bluegrass. Furthermore, the lipids selected in this study could serve as biomarkers for further improvement of salt-sensitive grass species.

Site-directed mutagenesis identified the key active site residues of 2,3-oxidosqualene cyclase HcOSC6 responsible for cucurbitacins biosynthesis in Hemsleya chinensis.

Hemsleya chinensis is a Chinese traditional medicinal plant, containing cucurbitacin IIa (CuIIa) and cucurbitacin IIb (CuIIb), both of which have a wide range of pharmacological effects, including antiallergic, anti-inflammatory, and anticancer properties. However, few studies have been explored on the key enzymes that are involved in cucurbitacins biosynthesis in H. chinensis. Oxidosqualene cyclase (OSC) is a vital enzyme for cyclizing 2,3-oxidosqualene and its analogues. Here, a gene encoding the oxidosqualene cyclase of H. chinensis (HcOSC6), catalyzing to produce cucurbitadienol, was used as a template of mutagenesis. With the assistance of AlphaFold2 and molecular docking, we have proposed for the first time to our knowledge the 3D structure of HcOSC6 and its binding features to 2,3-oxidosqualene. Mutagenesis experiments on HcOSC6 generated seventeen different single-point mutants, showing that single-residue changes could affect its activity. Three key amino acid residues of HcOSC6, E246, M261 and D490, were identified as a prominent role in controlling cyclization ability. Our findings not only comprehensively characterize three key residues that are potentially useful for producing cucurbitacins, but also provide insights into the significant role they could play in metabolic engineering.

ATP5D Is a Potential Biomarker for Male Fertility.

Background: Infertility is a global medical and social problem that affects human health and social development. At present, about 15% of couples of the right age in the world are infertile. As all we know, genetic defects are the most likely underlying cause of the pathology. ATP5D is also known as the delta subunit of mitochondrial ATP synthase. Mitochondria maintain sperm vitality, capacitation, acrosome reaction, and DNA integrity through ATP. Mitochondrial damage can trigger energy synthesis disorders, resulting in decreased sperm quality and function or even disappearance. The specific role of ATP5D in regulation of the male reproductive system remains elusive. Methods: In this study, semen from normal and infertile males were collected and their indicators were examined by analysis of routine sperm parameters; ATP5D protein content in semen was examined by ELISA. Singer sequencing was used to detect whether there was a mutated of ATP5D in semen. Meanwhile, ATP5D knockout (KO) and knockin (KI) male mice were selected at 8-12 weeks of age and mated with adult wild-type (WT) female mice for more than two months to assess their fertility and reproductive ability. Morphological changes in tissues such as testes and epididymis were observed by HE staining; spermatozoa were taken from the epididymis of the mice; sperm counts were performed and morphological changes were observed by Diff-Quik staining. Results: The results showed that the expression of ATP5D in infertile males was significantly lower than that in normal males (P < 0.001) and the normal morphology rate of spermatozoa was much lower than that of normal males, and the sequencing results showed no mutations. The animal reproductive experiments showed no significant changes in the number of fertility in KO/KI mice compared with WT mice, but the duration of fertility was significantly longer (P = 0.02). The testicular cells in KO mice were loosely arranged and disorganized, the lumen was larger, the interstitial cells were atrophied, and the number of spermatozoa was reduced and the malformation rate was higher in WT males. This suggests that ATP5D is an essential protein for sperm formation and fertility in male mice and may be used as a biomarker of male fertility. Conclusion: This study found ATP5D correlated with male infertility and the expression levels were significantly reduced in the seminal plasma of all male infertile patients without gene mutations. KO male significantly prolonged fertility time and impaired testicular histomorphology. This suggests that ATP5D may be associated with spermatogenic function and fertility in male mice and may be used as a biomarker for male fertility. Future studies are required to elucidate the potential mechanisms. The trial registration number is KLL-2021-266.

Quantitative analysis of Chinese steamed bread staling using NIR, MIR, and Raman spectral data fusion.

For efficient and comprehensive detection of the staling degree of Chinese steamed bread (CSB), staled CSB samples stored for 0-16 days were prepared and analyzed using near-infrared (NIR), mid-infrared (MIR), and Raman spectroscopy combined with data fusion. Among three data fusion schemes, decision-level fusion achieved the best performance when quantifying the CSB staling degree according to the soluble starch amylose fraction, relative crystallinity, and hardness, with determination coefficients and root mean square errors for the validation set in the range of 0.928-0.986 and 0.015-1.290, respectively. The relative percent deviation values of the three indicators increased to 8.362, 4.735, and 3.617, respectively. These results indicate that the combination of NIR, MIR, and Raman spectroscopy as a decision-level fusion scheme can achieve efficient, comprehensive, and accurate quantification of the staling degree of CSB. This research has important applications for food quality, safety, and shelf-life evaluations.

Study of starch aging characteristics based on Terahertz technology.

Traditional methods for the determination of starch aging indicators often have a series of shortcomings such as time-consuming, high cost, large human error, damage to samples, environmental pollution, and high requirements for inspectors. Therefore, it is meaningful to find or establish a dynamic fingerprint identification pattern that can detect the aging degree of starch during the process of processing or storage quickly and accurately. It not only provides guidance for starch food processing but also saves a lot of human, material resources, and time. Terahertz technology is an emerging molecular spectroscopy technology in the 21st century. It is with low energy and basically harmless to the human body. It can also realize nondestructive testing of samples. In the experiment, the samples were prepared by the tableting method and the samples containing 20% of 50 mg samples were prepared with polyethylene as the diluent. The thickness of the samples was 1 mm and the diameter was 13 mm. The terahertz time-domain spectrometer was used to obtain the spectral information of aging starch at different aging times. After the pretreatment of the spectrum by vector normalization, first derivative, and multiple scattering correction, the prediction models of aging days, crystallinity, and resilience of aging starch were established, respectively. The determination coefficient (R 2) of the established models is all greater than 95%, indicating that the established models are highly reliable and can be used to predict the aging days, crystallinity, and retrogradation degree of starch. And the R 2 of the prediction model based on the refractive index spectrum is greater than that of the absorption coefficient spectrum. The experimental method obtains the dynamic fingerprint identification map of starch in the aging process, realizes the real-time monitoring and detection of the starch aging process, and provides an effective means for the production and processing of starch-related industries.

Detection of carboxylesterase by a novel hydrosoluble near-infrared fluorescence probe.

A novel hydrosoluble near-infrared fluorescence off-on probe has been developed for detecting carboxylesterase activity. The probe was designed by introducing (4-acetoxybenzyl)oxy as a quenching and recognizing moiety to the decomposed product of IR-783, which exhibits excellent near-infrared fluorescence features and good water solubility. The responding mechanism of novel probe 1 to carboxylesterase was investigated. It would lead to the cleavage of the carboxylic ester bond by carboxylesterase catalyze the spontaneous hydrolysis of the probe, resulting in the release of a near-infrared fluorophore. This behaviour leads to the development of a simple and sensitive fluorescent method for assaying carboxylesterase activity, with a detection limit of 3.4 × 10-3 U mL-1. Moreover, the probe displays excellent selectivity toward carboxylesterase over other substances. Notably, the imaging experimental results showed that the probe 1 is cell membrane permeable, and its applicability has been demonstrated for monitoring carboxylesterase activity in HeLa cells.

Effects of Bilayer Thickness on the Morphological, Optical, and Electrical Properties of Al2O3/ZnO Nanolaminates.

This report mainly focuses on the investigation of morphological, optical, and electrical properties of Al2O3/ZnO nanolaminates regulated by varying bilayer thicknesses. The growth mechanism of nanolaminates based on atomic layer deposition and Al penetration into ZnO layer are proposed. The surface roughness of Al2O3/ZnO nanolaminates can be controlled due to the smooth effect of interposed Al2O3 layers. The thickness, optical constants, and bandgap information of nanolaminates have been investigated by spectroscopic ellipsometry measurement. The band gap and absorption edge have a blue shift with decreasing the bilayer thickness on account of the Burstein-Moss effect, the quantum confinement effect and the characteristic evolution of nanolaminates. Also, the carrier concentrations and resistivities are found to be modified considerably among various bilayer thicknesses. The modulations of these properties are vital for Al2O3/ZnO nanolaminates to be used as transparent conductor and high resistance layer in optoelectronic applications.

Effects of Al Doping on the Properties of ZnO Thin Films Deposited by Atomic Layer Deposition.

The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.

[Detection of Chlorpyrifos on Spinach Based on Surface Enhanced Raman Spectroscopy with Silver Colloids].

In this research, the surface enhanced Raman spectroscopy (SERS) technique is used to develop a nondestructive and fast detecting method for the detection of residual chlorpyrifos on spinach. Silver colloids used for SERS spectroscopy is prepared by the reduction of silver nitrate with hydroxylamine hydrochloride at alkaline pH. The prepared silver colloids are dropped onto spinach samples, then the SERS spectra are collected non-destructively with a self-developed Raman system. This method can be made without physical contact to samples, and rapidly completed without time-consuming sample pre-treatments, and suited to the development of real-time on-line detection methods for trace pesticide residues. SERS signals are collected from 20 points on each spinach sample with 450 mW laser power and 2.5 s exposure time. Chlorpyrifos concentrations in 24 samples are determined with gas chromatography after SERS spectra taken. Savitzky-Golay (SG) smoothing filter and effective peak linear fitting method are used to remove the random noise and the fluorescence background for improving the accuracy of SERS results. The SERS signals are collected from different parts of 50 spinach samples with the same concentration of chlorpyrifos but at different fresh degrees. The relative standard deviation (RSD) of chlorpyrifos' characteristic peak intensities is 13.4%. Although the differences of samples lead to differences in the curves of Raman spectrum, they have little influence on the characteristic peak intensities, which indicates the stability of the proposed detecting method. After the fluorescent background removed, the 20 curves of each sample are averaged. Correlation analysis is done between chlorpyrifos concentration and signal intensity at every Raman shift. Results show that correlation coefficients are higher than 0.85 in the range of 615.5~626.4 cm-1. Signals in this range are used to establish multiple linear regression (MLR) model for the prediction of residual chlorpyrifos. MLR model was developed for chlorpyrifos concentration versus Raman signal intensity at 615.5~626.4 cm-1 for predicting residual chlorpyrifos content in samples, the correlation coefficients of calibration (RC) and validation (RP) are 0.961 and 0.954, which indicate a good linear relationships between them. The minimum detectable threshold for this method is 0.05 mg·kg-1 which is close to the value limited by the national standard of China (0.1 mg·kg-1 for chlorpyrifos in spinach). The proposed practical method is sample, fast, without sample preparation, thus it shows great potential in safety detection of fruits and vegetables.

[A Point Raman Scanning Method for Rapidly Detection of Spinach Quality and Safety Parameters].

According to actual market demand for nondestructive detection of vegetables quality and safety, combined with the heterogeneity of quality and safety parameters such as pesticide residues on leaf vegetables surface and to realize the automatic point scanning for the whole leaf vegetables samples, a suction device based on laboratory (self-designed) Raman spectroscopy hardware and a GUI application software based on the LabVIEW development platform were developed. This system can test the Raman spectroscopy of the whole spinach including the automatic collection, display and storage of the Raman signal of all the scanned points by set up different scan step. A new method to remove the Raman spectrum background was proposed based on data replacement with linear equation at the range of threshold spectrum on both sides of the effective peaks according to the characteristics of spinach original spectra. Its principle is to determine the starting position of linear fitting by judging whether there is trough on both sides of the crest, and then to generate and replace the original spectra data in peak position through the linear fitting equation. Spinach samples were used for the experiment showed that the chlorophyll content and distribution of chlorpyrifos pesticide residue on each scanning point can be obtained after scanning. Therefore, the point scanning Raman system could improve detection accuracy of the quality and safety parameters for the non-uniform samples effectively.

[Research on Identification and Determination of Pesticides in Apples Using Raman Spectroscopy].

Raman spectroscopy combined with chemometric methods has been thought to an efficient method for identification and determination of pesticide residues in fruits and vegetables. In the present research, a rapid and nondestructive method was proposed and testified based on self-developed Raman system for the identification and determination of deltamethrin and acetamiprid remaining in apple. The peaks of Raman spectra at 574 and 843 cm(-1) can be used to identify deltamethrin and acetamiprid, respectively, the characteristic peaks of deltamethrin and acetamiprid were still visible when the concentrations of the two pesticides were 0.78 and 0.15 mg · kg(-1) in apples samples, respectively. Calibration models of pesticide content were developed by partial least square (PLS) algorithm with different spectra pretreatment methods (Savitzky-Golay smoothing, first derivative transformation, second derivative transformation, baseline calibration, standard normal variable transformation). The baseline calibration methods by 8th order polynomial fitting gave the best results. For deltamethrin, the obtained prediction coefficient (Rp) value from PLS model for the results of prediction and gas chromatography measurement was 0.94; and the root mean square error of prediction (RMSEP) was 0.55 mg · kg(-1). The values of Rp and RMSEP were respective 0.85 and 0.12 mg · kg(-1) for acetamiprid. According to the detect performance, applying Raman technology in the nondestructive determination of pesticide residuals in apples is feasible. In consideration of that it needs no pretreatment before spectra collection and causes no damage to sample, this technology can be used in detection department, fruit and vegetable processing enterprises, supermarket, and vegetable market. The result of this research is promising for development of industrially feasible technology for rapid, nondestructive and real time detection of different types of pesticide with its concentration in apples. This supplies a rapid nondestructive and environmentally friendly way for the determination of fruit and vegetable quality and safety.

[Protein interaction network analysis of Panax notoginseng saponins].

Panax notoginseng (PN) is one of the commonly used clinical medicines for cardiovascular diseases and possesses a variety of pharmacological effects. P. notoginseng saponins (PNS) are the most important bioactive components in PN. The purpose of this study was to explain the mechanism of PNS on molecular network level. 18 targets of the main medicinal ingredients of PNS were gained by virtual screening based on pharmacophores and data mining. A protein interaction network of PNS was constructed with 189 nodes and 721 interactions. By a graph theoretic clustering algorithm Molecular Complex Detection (MCODE), 14 modules were detected. Gene ontology (GO) enrichment analysis of the modules demonstrated that the roles of PNS played in cardiovascular disease related to multiple biological processes, which could represent the characteristics of traditional Chinese medicine (TCM) as a whole to regulate the disease. The results showed that the blood circulation and hemostasis efficacy of PN related with the biological processes such as positive regulation of cAMP metabolic and biosynthetic process, platelet activation and regulation of blood vessel size, regulation of T cell proliferation and differentiation and so on. Therefore, the module-based network analysis will be an effective method for better understanding TCM.

An acetylcholinesterase biosensor based on graphene-gold nanocomposite and calcined layered double hydroxide.

In this study, a novel acetylcholinesterase-based biosensor was fabricated. Acetylcholinesterase (AChE) was immobilized onto a glassy carbon electrode (GCE) with the aid of Cu-Mg-Al calcined layered double hydroxide (CLDH). CLDH can provide a bigger effective surface area for AChE loading, which could improve the precision and stability of AChE biosensor. However, the poor electroconductibility of CLDHs could lead to the low sensitivity of AChE biosensor. In order to effectively compensate the disadvantages of CLDHs, graphene-gold nanocomposites were used for improving the electron transfer rate. Thus, the graphene-gold nanocomposite (GN-AuNPs) was firstly modified onto the GCE, and then the prepared CLDH-AChE composite was immobilized onto the modified GCE to construct a sensitive AChE biosensor for pesticides detection. Relevant parameters were studied in detail and optimized, including the pH of the acetylthiocholine chloride (ATCl) solution, the amount of AChE immobilized on the biosensor and the inhibition time governing the analytical performance of the biosensor. The biosensor detected chlorpyrifos at concentrations ranging from 0.05 to 150µg/L. The detection limit for chlorpyrifos was 0.05µg/L.

[Clinical analysis of hypoparathyroidism with altered serum muscle enzymes: report of 41 cases].

OBJECTIVE: To examine the clinical features of hypoparathyroidism (HP) with altered serum muscle enzymes and explore the correlations with age, gender, disease duration, serum total calcium, serum total phosphorus and parathyroid hormone (PTH). METHODS: From January 2005 to October 2011, a total of 41 HP patients at our hospital were retrospectively analyzed. RESULTS: There were 16 patients with elevated serum muscle enzymes and 25 with normal serum muscle enzymes. The former group included 11 patients of idiopathic hypoparathyroidism (IHP) and 5 of pseudohypoparathyroidism (PHP); serum calcium was (1.53 ± 0.25) mmol/L and serum phosphorus (2.1 ± 0.6) mmol/L; medians of creatine kinase (CK), lactic dehydrogenase (LDH), aspartate amino transfer enzymes (AST) were 309 (126 - 10 046), 279 (131 - 741) and 27 (17 - 467) U/L in HP patients respectively. And the latter group included 20 IHP patients and 5 PHP ones; serum calcium was (1.64 ± 0.29) mmol/L and serum phosphorus (2.2 ± 0.6) mmol/L. The levels of serum muscle enzyme were compared before and after treatment in the former group. And they significantly declined with the rising serum level of calcium after treatment. The serum levels of CK (r = -0.82), LDH (r = -0.55) and AST (r = -0.56) in HP patients with elevated serum muscle enzymes had a negative correlation with the serum level of calcium (all P < 0.05). And there was no correlation with age, gender, disease duration or serum total phosphorus (P > 0.05). CONCLUSION: Elevated serum muscle enzymes in HP patients have a negative correlation with serum level of calcium and there is no correlation with age, gender, disease duration, serum total phosphorus or parathyroid hormone. And elevated serum muscle enzymes are gradually restored with the normalized serum level of calcium.

A novel and highly sensitive acetyl-cholinesterase biosensor modified with hollow gold nanospheres.

In this work, a highly sensitive acetylcholinesterase (AChE) inhibition-based amperometric biosensor has been developed. Firstly, a glassy carbon electrode (GCE) was modified with chitosan (Chits). Then, hollow gold nanospheres (HGNs) were absorbed onto the surface of chitosan based on the strong affinity through electrostatic adsorption. After that, L-cysteine (L-cys) was assembled on HGNs through Au-S bond. The hollow gold nanospheres were prepared by using Co nanoparticles as sacrificial templates and characterized by scanning electron microscopy, transmission electron microscopy and ultraviolet spectra, respectively. Finally, AChE was immobilized with covalent binding via -COOH groups of L-cysteine onto the modified GCE. The AChE biosensor fabrication process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy methods with the use of ferricyanide as an electrochemical redox indicator. Under optimum conditions, the inhibition rates of pesticides were proportional to their concentrations in the range of 0.1-150 and 0.1-200 µg L(-1) for chlorpyrifos and carbofuran, respectively, the detection limits were 0.06 µg L(-1) for chlorpyrifos and 0.08 µg L(-1) for carbofuran. Moreover, the biosensor exhibited a good stability and reproducibility and was suitable for trace detection of pesticide residues in vegetables and fruits.

Acetylcholinesterase biosensor based on chitosan/prussian blue/multiwall carbon nanotubes/hollow gold nanospheres nanocomposite film by one-step electrodeposition.

In this paper, chitosan-prussian blue-multiwall carbon nanotubes-hollow gold nanospheres (Chit-PB-MWNTs-HGNs) film was fabricated onto the gold electrode surface by one-step electrodeposition method; and then acetylcholinesterase (AChE) and Nafion were modified onto the film to prepare an AChE biosensor. Incorporating MWNTs and HGNs into Chit-PB hybrid film promoted electron transfer reaction, enhanced the electrochemical response and improved the microarchitecture of the electrode surface. The morphologies and electrochemistry properties of the composite were investigated by using scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. Parameters affecting the biosensor response such as pH, enzyme loading and inhibition time were optimized. Based on the inhibition of pesticides on the AChE activity, using malathion, chlorpyrifos, monocrotophos and carbofuran as model compounds, this biosensor showed a wide range, low detection limit, good reproducibility and high stability. Moreover, AChE/Chit-PB-MWNTs-HGNs/Au biosensor can also be used for direct analysis of practical samples, which would be a new promising tool for pesticide analysis.