Comparing visible and near infrared 'point' spectroscopy and hyperspectral imaging techniques to visualize the variability of apple firmness.

In this work, visible and near-infrared 'point' (Vis-NIR) spectroscopy and hyperspectral imaging (Vis-NIR-HSI) techniques were applied on three different apple cultivars to compare their firmness prediction performances based on a large intra-variability of individual fruit, and develop rapid and simple models to visualize the variability of apple firmness on three apple cultivars. Apples with high degree of intra-variability can strongly affect the prediction model performances. The apple firmness prediction accuracy can be improved based on the large intra-variability samples with the coefficient variation (CV) values over 10%. The least squares-support vector machine (LS-SVM) models based on Vis-NIR-HSI spectra had better performances for firmness prediction than that of Vis-NIR spectroscopy, with the with the Rc2 over 0.84. Finally, The Vis-NIR-HSI technique combined with least squares-support vector machine (LS-SVM) models were successfully applied to visualize the spatial the variability of apple firmness.

High-Performance Monolithic 3D Integrated Complementary Inverters Based on Monolayer n-MoS2 and p-WSe2.

Herein, the structure of integrated M3D inverters are successfully demonstrated where a chemical vapor deposition (CVD) synthesized monolayer WSe2 p-type nanosheet FET is vertically integrated on top of CVD synthesized monolayer MoS2 n-type film FET arrays (2.5 × 2.5 cm) by semiconductor industry techniques, such as transfer, e-beam evaporation (EBV), and plasma etching processes. A low temperature (below 250 °C) is employed to protect the WSe2 and MoS2 channel materials from thermal decomposition during the whole fabrication process. The MoS2 NMOS and WSe2 PMOS device fabricated show an on/off current ratio exceeding 106 and the integrated M3D inverters indicate an average voltage gain of ≈9 at VDD = 2 V. In addition, the integrated M3D inverter demonstrates an ultra-low power consumption of 0.112 nW at a VDD of 1 V. Statistical analysis of the fabricated inverters devices shows their high reliability, rendering them suitable for large-area applications. The successful demonstration of M3D inverters based on large-scale 2D monolayer TMDs indicate their high potential for advancing the application of 2D TMDs in future integrated circuits.

A Novel Variable Selection Method Based on Ordered Predictors Selection and Successive Projections Algorithm for Predicting Gastrodin Content in Fresh Gastrodia elata Using Fourier Transform Near-Infrared Spectroscopy and Chemometrics.

Gastrodin is one of the most important biologically active components of Gastrodia elata, which has many health benefits as a dietary and health food supplement. However, gastrodin measurement traditionally relies on laboratory and sophisticated instruments. This research was aimed at developing a rapid and non-destructive method based on Fourier transform near infrared (FT-NIR) to predict gastrodin content in fresh Gastrodia elata. Auto-ordered predictors selection (autoOPS) and successive projections algorithm (SPA) were applied to select the most informative variables related to gastrodin content. Based on that, partial least squares regression (PLSR) and multiple linear regression (MLR) models were compared. The autoOPS-SPA-MLR model showed the best prediction performances, with the determination coefficient of prediction (Rp2), ratio performance deviation (RPD) and range error ratio (RER) values of 0.9712, 5.83 and 27.65, respectively. Consequently, these results indicated that FT-NIRS technique combined with chemometrics could be an efficient tool to rapidly quantify gastrodin in Gastrodia elata and thus facilitate quality control of Gastrodia elata.

Study on Black Spot Disease Detection and Pathogenic Process Visualization on Winter Jujubes Using Hyperspectral Imaging System.

In this work, the potential of a hyperspectral imaging (HSI) system for the detection of black spot disease on winter jujubes infected by Alternaria alternata during postharvest storage was investigated. The HSI images were acquired using two systems in the visible and near-infrared (Vis-NIR, 400-1000 nm) and short-wave infrared (SWIR, 1000-2000 nm) spectral regions. Meanwhile, the change of physical (peel color, weight loss) and chemical parameters (soluble solids content, chlorophyll) and the microstructure of winter jujubes during the pathogenic process were measured. The results showed the spectral reflectance of jujubes in both the Vis-NIR and SWIR wavelength ranges presented an overall downtrend during the infection. Partial least squares discriminant models (PLS-DA) based on the HSI spectra in Vis-NIR and SWIR regions of jujubes both gave satisfactory discrimination accuracy for the disease detection, with classification rates of over 92.31% and 91.03%, respectively. Principal component analysis (PCA) was carried out on the HSI images of jujubes to visualize their infected areas during the pathogenic process. The first principal component of the HSI spectra in the Vis-NIR region could highlight the diseased areas of the infected jujubes. Consequently, Vis-NIR HSI and NIR HSI techniques had the potential to detect the black spot disease on winter jujubes during the postharvest storage, and the Vis-NIR HSI spectral information could visualize the diseased areas of jujubes during the pathogenic process.

Assessment of the optical properties with physicochemical properties and cell wall polysaccharides of 'Korla' pear flesh during Alternaria alternata-induced disease development.

Cell wall polysaccharides and physicochemical properties are the major quality characteristics of fruit, but they are significantly affected by the postharvest disease. In this study, the influence of Alternaria alternata-induced disease on the contents of cell wall polysaccharides and physicochemical properties in 'Korla' pear flesh during storage, as well as their relationships of the optical absorption (µa) and reduced scattering (µs') were explored. The infected pear had lower individual sugars, covalent-soluble pectin, cellulose and hemicellulose contents than the healthy ones. The successive decreases of µa and increases of µs' in pears were observed while the process of pathogen infection. Path-coefficient analysis indicated the ionic-soluble pectin was the main reason responsible for the change of µs' in infected pear at 675 nm and 980 nm. This study indicated the optical properties have the possibility to present the physicochemical characteristics and cell wall polysaccharides of pears during postharvest pathogen infection.

Detection of Alternaria alternata infection in winter jujubes based on optical properties and their correlation with internal quality parameters during storage.

In this work, a single integrating sphere system was applied to characterize the optical absorption (µa) and reduced scattering (µs') properties (550 - 1050 nm) in winter jujube flesh infected by Alternaria alternata during storage at 4 and 20 °C, respectively. Meanwhile, physical (L*, a*, weight loss) and biochemical characteristics (soluble solids content, titratable acids, chlorophyll, total phenolic, and ascorbic acid) of winter jujubes were measured. Among them, chlorophyll, weight loss and ascorbic acid were highly correlated with µa at 680 nm, 690 nm, while chlorophyll and a* had the best correlations with µs' at 700 - 920 nm. These optimal optical properties were proved efficiently contributed to the disease detection of winter jujubes after 12 days at 4 °C and 3 days at 20 °C during storage, with satisfactory discrimination accuracies (acc > 93.75 %). Consequently, optical properties in Vis-NIR region were available to detect the postharvest disease in winter jujubes.

Fruit variability impacts puree quality: Assessment on individually processed apples using the visible and near infrared spectroscopy.

This study was designed to have the absolute definition of 'one apple to one puree', which gave a first insight into the impacts of fruit inter-variability (between varieties) and intra-variability (between individual fruits) on the quality of processed purees. Both the inter-variability of apple varieties and the intra-variability of single apples induced intensive changes of appearance, chemical and textural properties of their corresponding microwave-cooked purees. The intra-variability of cooked purees was different according to apple cultivars. Some strong correlations of visible-near infrared (VIS-NIR) spectra were observed between fresh and cooked apples, particularly in the regions 665-685 nm and 1125-1400 nm. These correlations allowed then the indirect predictions of puree color (a* and b*, RPD ≧ 2.1), viscosity (RPD ≧ 2.3), soluble solids content (SSC, RPD = 2.1), titratable acidity (RPD = 2.8), and pH (RPD = 2.5) from the non-destructive acquired VIS-NIR spectra of raw apples.

Mid-infrared technique to forecast cooked puree properties from raw apples: A potential strategy towards sustainability and precision processing.

The potential of MIRS was investigated to: i) differentiate cooked purees issued from different apples and process conditions, and ii) predict the puree quality characteristics from the spectra of homogenized raw apples. Partial least squares (PLS) regression was tested both, on the real spectra of cooked purees and their reconstructed spectra calculated from the spectra of homogenized raw apples by direct standardization. The cooked purees were well-classified according to apple thinning practices and cold storage durations, and to different heating and grinding conditions. PLS models using the spectra of homogenized raw apples can anticipate the titratable acidity (the residual predictive deviation (RPD) = 2.9), soluble solid content (RPD = 2.8), particle averaged size (RPD = 2.6) and viscosity (RPD ≥ 2.5) of cooked purees. MIR technique can provide sustainable evaluations of puree quality, and even forecast texture and taste of purees based on the prior information of raw materials.

Development of red apple pomace extract/chitosan-based films reinforced by TiO2 nanoparticles as a multifunctional packaging material.

A chitosan-based (CS) film was developed with nanosized TiO2 and red apple pomace extract (APE). The intermolecular interactions of CS, TiO2 and APE were evaluated by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. TiO2 nanoparticles remarkably improved the water vapor and UV-Vis light barrier properties, mechanical strength and thermal stability of CS-APE films. The strong antioxidant abilities of CS-APE and CS-TiO2-APE films were characterized. Nano-TiO2 and APE showed a synergistic enhancement of the antimicrobial activity in CS matrix. The addition of TiO2 nano-particles into CS-APE films resulted the sensitive color variations, which applied successfully as an indicator to monitor the freshness of salmon fillets. Consequently, the development of CS-APE-TiO2 film provides a new solution to convert rad apple pomace to an active and multifunctional food packaging material with considerable mechanical, antibacterial, antioxidant and pH-responsive color-changing properties.

Fresh, freeze-dried or cell wall samples: Which is the most appropriate to determine chemical, structural and rheological variations during apple processing using ATR-FTIR spectroscopy?

Attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR) was applied on fresh (NF), freeze-dried (FD) and cell wall materials (AIS) of raw and processed apples. These samples prepared from 36 apple sets and the corresponding 72 purees, issued from different varieties, agricultural practices, storage periods and processing conditions, were used to build models including exploratory analysis, supervised classification and multivariate calibration. Fresh and freeze-dried samples presented similar fingerprint spectral variations due to processing. ATR-FTIR directly on fresh purees satisfactorily predicted textural properties such as particle average size and volume (RPD > 3.0), while freeze-drying improved assessment of chemical (RPD > 3.2) and rheological (RPD > 3.1) parameters using partial least-squares regression. The assessment of texture and macrocomponents of purees can be obtained with a limited sample preparation. For research applications because of a need of sample preparation, changes of cell wall composition during fruit processing could be assessed in relationship with pectin degradation.

Developing poly(vinyl alcohol)/chitosan films incorporate with d-limonene: Study of structural, antibacterial, and fruit preservation properties.

Active biodegradable packaging films were developed with polyvinyl alcohol (PVA), chitosan (CS) and d-Limonene (DL). The effect of various DL content levels (0%, 2.5%, 5%, 7.5%, and 10% w/w) on the structural, mechanical, biodegradable and antimicrobial properties of PVA/CS films was systematically studied. Good compatibility between DL and PVA/CS, and good dispersion of DL in the PVA/CS matrix were demonstrated by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). PVA/CS films greatly improved their antibacterial, mechanical and barrier properties, which are associated with the considerable biodegradability, after they were incorporated with DL. However, the overloading with DL may weaken hydrogen bonds between polymer chains, resulting in the negative effects on the physical performances of the film. Particularly, the PVA/CS/DL-5% film showed the highest water contact angle and transmittance value, and also showed effective preservations of packaged mango fruits during 10 day of storage at 20 ± 2 °C, based on the characterization by fruits weight loss, decay rate, firmness, titratable acidity, soluble solids, and ascorbic acid. Consequently, DL/PVA/CS composite films may be a promising eco-friendly packaging material for food preservation.

A new application of NIR spectroscopy to describe and predict purees quality from the non-destructive apple measurements.

The potential of NIRS was investigated on both apples and purees to (i) examine factors involving quality variability (variety, agricultural practice, cold storage, puree mechanical refining level) and (ii) establish the link between quality traits before and after processing in order to predict the quality characteristics of purees from spectral information of raw apples. Apples and purees were well-classified at over 82% and 88% according to varieties and storage times respectively. The PLS models showed a good ability to estimate puree characteristics from spectra acquired on corresponding apples such as viscosity (R2 > 0.82), cell wall content (R2 > 0.81) and also dry matter (R2 > 0.83), soluble solids content (R2 > 0.80) and titratable acidity (R2 > 0.80). NIR technique should be a useful tool for industry insofar as it can give a reliable assessment of texture and taste of the final products based on the non-destructive fresh materials evaluation.

Chromosome segregation errors generate a diverse spectrum of simple and complex genomic rearrangements.

Cancer genomes are frequently characterized by numerical and structural chromosomal abnormalities. Here we integrated a centromere-specific inactivation approach with selection for a conditionally essential gene, a strategy termed CEN-SELECT, to systematically interrogate the structural landscape of mis-segregated chromosomes. We show that single-chromosome mis-segregation into a micronucleus can directly trigger a broad spectrum of genomic rearrangement types. Cytogenetic profiling revealed that mis-segregated chromosomes exhibit 120-fold-higher susceptibility to developing seven major categories of structural aberrations, including translocations, insertions, deletions, and complex reassembly through chromothripsis coupled to classical non-homologous end joining. Whole-genome sequencing of clonally propagated rearrangements identified random patterns of clustered breakpoints with copy-number alterations resulting in interspersed gene deletions and extrachromosomal DNA amplification events. We conclude that individual chromosome segregation errors during mitotic cell division are sufficient to drive extensive structural variations that recapitulate genomic features commonly associated with human disease.

Electrospun Polyvinyl Alcohol/d-Limonene Fibers Prepared by Ultrasonic Processing for Antibacterial Active Packaging Material.

Novel fibers containing different ratios of PVA and d-limonene were fabricated using electrospinning for antibacterial active packaging applications. The PVA/d-limonene fibers were thoroughly characterized using a scanning electron microscope, fourier-transform infrared spectrometry, thermal gravimetry, differential scanning calorimetry, tensile tests, and oxygen permeability tests. The results of these analyses showed that the highest tensile strength and elongation at break values of 3.87 ± 0.25 MPa and 55.62 ± 2.93%, respectively, were achieved for a PVA/d-limonene ratio of 7:3 (v/v) and an ultrasonication time of 15 min during processing. This material also showed the lowest oxygen permeation and the best degradability and bacteriostatic properties of all samples.

Development of ultrasound treated polyvinyl alcohol/tea polyphenol composite films and their physicochemical properties.

In this study, polyvinyl alcohol (PVA) was used as a film-forming substrate, added to extracted tea polyphenols (TPs) in various ratios and processed with ultrasonication to form films using the tape-casting method. The effects of ultrasonic processing duration on the properties of PVA/TP antibacterial active materials were explored via material property testing. The results showed that, overall, ultrasonic processing degraded the tensile strength and elongation at break of the composite films. When PVA/TP composite films with a PVA-to-TP mass ratio of 8:2 were processed with ultrasonication for 30 min, the swelling capacity was (740.19 ±â€¯64.67)% and solubility was (5.26 ±â€¯1.31)%. Ultrasonication also improved the degradability and barrier properties of composite films. Moreover, 8/2 composite films with the PVA/TP ratio of 8:2 exhibited excellent bacteriostatic properties; after ultrasonication processing, the films had a bacteriostatic rate of (95.5 ±â€¯4.2)% and (91.8 ±â€¯3.7)% against Staphylococcus aureus and Escherichia coli, respectively, making them suitable for use as antibacterial active materials in food packaging.

Fabrication of polylactic acid/carbon nanotubes/chitosan composite fibers by electrospinning for strawberry preservation.

In this study, we employed electrospinning to fabricate polylactic acid (PLA)/carbon nanotubes (CNTs)/chitosan (CS) composite fibers containing different CS contents and examined the ability of these fibers for strawberry preservation for the first time. The experimental results showed that as CS content increased, the mechanical properties, solubility, and swelling ratio of the fiber films first improved and then degraded, with peak values being achieved at a CS content of 7 wt%. The antimicrobial activity test results showed that as CS content increased, the antimicrobial activity of the composite fiber films against four microorganisms increased and the activity was the best when the CS content was 7 wt%. In addition, the composite fibers exhibited better antimicrobial activity against Gram-negative and -positive bacteria than against molds. Moreover, the fibers exhibited better antimicrobial activity against Staphylococcus aureus than against Escherichia coli. The preservation experiments showed that the nanocomposite fibers containing different CS contents exhibited good preservation effects for strawberries, with the fiber containing 7 wt% CS showing the best results. Thus, these fibers can delay the physiological changes in strawberries and extend their shelf life and therefore have important potential applications for fruit and vegetable preservation in the future.

Preparation and properties of polylactic acid-tea polyphenol-chitosan composite membranes.

To study the properties of composite membranes consisting of polylactic acid (PLA), tea polyphenol (TP), and chitosan (CS), the stretch film method was employed to make PLA-TP- CS composite membranes of different concentrations. By testing the density, mechanical properties, heat-sealing performance, water vapor permeability, and solubility of the pure PLA membrane and the composite membranes, the comprehensive performance of the composite membranes were analyzed with regard to the actual use value. The results show that, compared with the pure PLA membrane, adding TP and CS significantly increases the heat-sealing strength, water vapor permeability, and solubility of the composite membrane. When the composite membrane is used for the preservation of cherries, it is found that the composite membrane with the mass ratio of TP to CS of 3:7 can decrease the rotting rate and mass loss rate significantly, postpone the consumption of soluble solids and vitamin C, maintain the quality of the cherries, and extend the shelf life, thus proving its potential for application in food packaging.

Study on the synthesis and physicochemical properties of starch acetate with low substitution under microwave assistance.

In this study, synthesis and physicochemical properties of starch acetate with low substitution under microwave were studied. A three-level-three-factorial Central Composite Design using Response Surface Methodology (RSM) was employed to optimize the reaction conditions. The optimal parameters are as follows: amount of acetic anhydride of 12%, radiation time of 11min, and microwave power of 100W. These optimal conditions predicted by RSM were confirmed that the degree of substitution (DS) of acetate starch is 0.0691mg/g and the physical and chemical properties of natural corn starch (NCS) and corn starch acetate (ACS) were further studied.The transparency, water separation, water absorption, expansion force, and solubility of ACS low substitution are better than NCS, while the NCS's hydrolysis percentage is higher than ACS, which indicate that the modified corn starch has better performance than native corn starch. The surface morphology of the corn starch acetate was examined by scanning electron microscope (SEM), which showed that it had a smooth surface and a spherical and polygonal shape. However, samples' shape is irregular. Crystal structure was observed by X-ray diffraction, and the ACS can determine the level of microwave technology that can destroy the extent of the crystal and amorphous regions. Fourier transform infrared (FTIR) spectroscopy shows that around 1750cm-1 carbonyl signal determines acetylation bonding successfully.

Effect of extraction methods on the properties and antioxidant activities of Chuanminshen violaceum polysaccharides.

The yields, properties and antioxidant activities of polysaccharides extracted from Chuanminshen violaceum (CVPs) by various methods including heated reflux extraction (HRE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), were evaluated. The results indicated that the yield of the polysaccharides (34.59%) obtained by MAE was higher than those obtained by other methods. Polysaccharides extracted by all three methods had similar physicochemical characteristics and FT-IR spectra. However, SEM images of particles of Chuanminshen violaceum treated by the three different methods were significantly different. Compared with HRE, UAE and MAE resulted in CVPs with lower molecular weight distributions and higher reducing power and scavenging abilities for ABTS + and DPPH. CVPs obtained by UAE had reduced scavenging abilities for DPPH compared to those obtained by MAE. These data indicated that MAE resulted in better extraction yields for CVPs and also resulted in CVPs with higher bioactivity.

Extraction, characterization and antioxidant activities of polysaccharides of Chuanminshen violaceum.

A single factor experiment and Box-Behnken design were applied to optimize the microwave-assisted extraction (MAE) of Chuanminshen violaceum polysaccharides (CVPs). The CVPs yield was 34.59 ± 0.51%, which was in accordance with the predicted value of 35.54%, under the following optimum conditions: microwave power of 466 W, extraction temperature of 64.5 °C, extraction time of 15 min, and water-raw material ratio of 40 mL/g. Two CVPs fractions (CVPs-I and CVPs-II) were obtained via stepwise ethanol precipitation. CVPs-II was further purified using DEAE cellulose-52 chromatography to obtain the major fraction of CVPs-IIa. Fourier transform infrared spectroscopy (FTIR) and GC-MS analysis revealed that crude CVPs, CVPs-I, and CVPs-II were neutral polysaccharides and were mainly composed of glucose and galactose. The molecular weights of CVPs-I and CVPs-IIa were 233.69 and 11.02 kDa, respectively. Furthermore, all samples exhibited certain antioxidant activity or reducing power to scavenge the DPPH and ABTS radicals, among which CVPs-II was the strongest. In conclusion, MAE is an efficient method for extracting CVPs of C. violaceum, and this plant root has the potential to be explored as a source of natural antioxidants.