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Remaining useful life (RUL) prediction of aircraft engines is significant in the health monitoring, operation, and maintenance of aircraft. Capturing more comprehensive device degradation trends at different time scales and extracting long-term dependencies effectively among elements in long time series are two challenges in the field of aircraft engine RUL estimation. To address the aforementioned challenges, this paper proposes a novel multiscale Hourglass-Transformer (MHT) aircraft engine RUL prognostics. Specifically, an hourglass-shaped multiscale feature extractor (HME) is designed based on one-dimensional convolutional neural network, which can scale the time sequence into multi-time scales for feature fusion. Then, a transformer network is employed to further extract features from the fused feature map and output the RUL. To enhance inter-scale data attention, a pyramid self-attention mechanism is employed in both the encoder and decoder. Finally, the superiority and effectiveness of this approach are verified on the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) dataset. Furthermore, the robustness and generalization capability of this method are further validated on New Commercial Modular Aero-Propulsion System Simulation (N-CMAPSS) dataset. • A novel multiscale Hourglass-Transformer is developed for aircraft engine RUL prognostics. • An hourglass-shaped multiscale feature extractor is designed based on one-dimensional convolutional neural network. • A transformer network is employed to further extract features. • Pyramid self-attention mechanism is adopted to reduce space complexity. [ABSTRACT FROM AUTHOR]

In the present study, apple peel polyphenols (APP) were incorporated into chitosan (CS) to develop a novel functional film. Scanning electron microscopy, Fourier transform-infrared spectroscopy and thermogravimetric analyses were performed to study the structure, potential interaction and thermal stability of the prepared films. Physical properties including moisture content, density, color, opacity, water solubility, swelling ration and water vapor permeability were measured. The results revealed that addition of APP into CS significantly improved the physical properties of the film by increasing its thickness, density, solubility, opacity and swelling ratio whereas moisture content and water vapor permeability were decreased. Tensile strength and elongation at break of the CS-APP film with 1% APP was 16.48 MPa and 13.33%, respectively, significantly lower than those for CS control film. Thermal stability of the prepared films was decreased while antioxidant and antimicrobial activities of the CS-based APP film were significantly increased. CS-APP film with 0.50% APP concentration exhibited good mechanical and antimicrobial properties, indicating that it could be developed as bio-composite food packaging material for the food industry. [ABSTRACT FROM AUTHOR]

In the present study, pear polyphenol oxidase (PPO) was purified, immobilized and applied for the synthesis of theaflavin-3,3′-digallate (TF3). Firstly, PPO of pear ( Pyrus bretschneideri Rehd cv. Huangguan) was purified 24.36-fold in specific activity with a recovery of 6.77% by sequential use of precipitation with 70% saturated ammonium sulfate and chromatography of DEAE-Sepharose Fast Flow column. The purified pear PPO, found to be a dimer of identical subunits of molecular mass 35 kDa, was then successfully immobilized onto Fe 3 O 4 /chitosan nanoparticles via glutaraldehyde coupling reaction. Finally, TF3 was effectively synthesized by applying the immobilized PPO as biocatalyst with epicatechin gallate (ECG) and epigallocatechin-3- O -gallate (EGCG) as substrates, and the maximum yield of TF3 was 42.23% based on the amount of ECG added. In addition, the immobilized enzyme still remained 85% of its initial ability after successive usage of 8 cycles and could be stored for 30 days with less loss of activity. All the results suggest that the developed procedure is quite useful and has great potential for synthesis of TF3 and other theaflavins. [ABSTRACT FROM AUTHOR]

A new parameter-free framework for calibration enhancement (PFCE) was proposed for dealing with the near-infrared (NIR) spectral inconsistency and maintaining the prediction ability of the calibration model under different conditions. The calibration issues encountered in the maintenance with or without using standards, and even the enhancement between instruments have been thoroughly addressed. The general calibration maintenance/enhancement cases were formulated into non-supervised PFCE (NS-PFCE), semi-supervised PFCE (SS-PFCE), and full-supervised PFCE (FS-PFCE). The NS-PFCE made use of both the provided master and slave spectra of standard samples to construct a maintained calibration slave model by implementing a correlation constraint on the regression coefficients. The SS-PFCE and FS-PFCE methods integrated the slave spectra and reference information of standard samples at the same time into the slave spectral calibration, and thus a maintenance or enhancement model could be achieved for the slave spectra, in particular measured on different instruments. The use of dataset1 comprised of 655 pharmaceutical tablets measured on two NIR spectrometers and datset2 containing 117 plant leaf samples in two mesh sizes has demonstrated that the PFCE framework had a significant effect on enhancing the predictions of the slave spectra in the models. The root mean square errors of prediction (RMSEPs) of either active pharmaceutical ingredient (API) amount in tablets or reducing sugar content in plant leaf samples from the slave spectra approached to or were lower than those values predicted from the master spectra in the master models established with the partial least-squares (PLS) regression method. The advantage of PFCE was parameter-free and efficient. First, the method could be flexibly employed in scientific or applicative environment with no regard to the parameter specification. Second, the performance of NS-PFCE was comparable to the classical calibration maintenance methods, yet the SS-PFCE and FS-PFCE could enhance the prediction ability to a level widely considered as the upper boundary of classical calibration maintenance methods reached.The source code of the method is available at https://github.com/JinZhangLab/PFCE. Image 1 • New, efficient parameter-free framework for calibration enhancement (PFCE) of NIR spectroscopy. • Formulating the calibration maintenance and enhancement into non-supervised, semi-supervised, and full-supervised cases. • Dealing with spectral inconsistency and maintaining prediction ability of calibration model under different conditions. • PFCE constructing a maintained or enhanced calibration model by a correlation constraint on the regression coefficients. • The PFCE model resulting in more accurate predicition. [ABSTRACT FROM AUTHOR]

Microbial and enzymatic inactivation in fresh pear juice were studied under conventional and ultrasound-pasteurizations. The ultrasound-pasteurization conditions were 25, 45 and 65 °C for 10 min using a 750 W probe sonicator (frequency 20 kHz and amplitude 70%) while conventional pasteurization conditions were 65 °C for 10 min and 95 °C for 2 min. Complete inactivation of enzymes (peroxidase, pectinmethylesterase and polyphenol oxidase) and microbes (total plate count, yeast and mould) were observed in conventional pasteurization at 95 °C but this treatment also showed highest losses of ascorbic acid, total phenols, flavonoids and antioxidant capacity. Ultrasound-pasteurization at 65 °C for 10 min showed the best results in retention of ascorbic acid and other phenolic compounds with significant reduction in enzyme activities and complete inactivation of microbes. Values of pH, acidity and °Brix showed no significant changes under conventional or ultrasound-pasteurization treatments. The findings of the present study indicate that pasteurization at low temperatures in combination with ultrasound can successfully be employed for commercial processing of pear juice with improved quality. [ABSTRACT FROM AUTHOR]

To detect more credibly the changes in the crystal structure of chickpea starch during processing treatments, two methods, a deconvolution method based on X-ray diffraction (XRD) pattern of starch and a moisture analysis method based on starch moisture content, were applied to determine the relative crystallinity ( RC ) of A- and B-type polymorphs ( RC A and RC B ) in the same chickpea starch sample. It was found that the values of RC A for chickpea starch samples determined by these two methods were close and showed similar trend. The results suggested that these two methods could be used to estimate RC A in the same chickpea starch sample and provide mutual corroboration. Based on the deconvolution method, it was observed that the crystalline region of chickpea starch was less susceptible to α-amylase hydrolysis than its amorphous region, and B-type polymorph in chickpea starch was more resistant to α-amylase hydrolysis than A-type polymorph. [ABSTRACT FROM AUTHOR]

The combined effects of ultrasound ( US) and high hydrostatic pressure ( HHP) on enzymes, micro-organisms, colouring pigments, total polyphenols, ascorbic acid and physicochemical properties of carrot juice were investigated. Carrot juice was treated with sonication (20 kHz, 70% amplitude) and HHP (250, 350, 450 MPa) at room temperature for 10 min. For comparison, fresh carrots were water blanched ( WB) at 100 °C for 4 min and carrot juice was then extracted. As results, highest improvements in colouring pigments were observed in WB and US- HHP450 treatments, which also completely inactivated micro-organisms. The highest reduction in enzymes was observed in WB treatment followed by US- HHP450. Total polyphenol contents increased significantly in US, HHP and US- HHP treatments with the highest increase in US- HHP450, but it decreased significantly in WB treatment. Ascorbic acid contents significantly decreased in WB and HHP450, while increased in US and US- HHP treatments. Results indicate that US- HHP450 treatment improves the quality of carrot juice and serves as a good alternative for blanching treatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Quality enhancement of apple juice by thermosonication has been investigated. [•] Thermosonication enabled inactivation of enzymes and microbes of apple juice. [•] Retention of ascorbic acid and polyphenolic compounds was observed. [•] The pH, titratable acidity and °Brix remained unaffected. [•] The technique could be efficiently utilized for apple juice processing. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the combined effects of blanching and sonication on carrot juice quality. Carrots were blanched at 100 °C for 4 min in normal and acidified water. Juice was extracted and sonicated at 15 °C for 2 min keeping pulse duration 5 s on and 5 s off (70% amplitude level and 20 kHz frequency). No significant effect of blanching and sonication was observed on Brix, pH and titratable acidity except acidified blanching that decreased pH and increased acidity significantly. Peroxidase was inactivated after blanching that also significantly decreased total phenol, flavonoids, tannins, free radical scavenging activity, antioxidant capacity and ascorbic acid and increased cloud and color values. Sonication could improve all these parameters significantly. The present results suggest that combination of blanching and sonication may be employed in food industry to produce high-quality carrot juice with reduced enzyme activity and improved nutrition. [ABSTRACT FROM AUTHOR]

Abstract: A study was conducted to evaluate the influence of blanching and sonication on important quality parameters of carrot juice. Blanching of carrots was done in normal water and acidified water (45 g/L citric acid, pH 1.3) at 100 °C for 4min and juice was extracted. Sonication of juice was done (frequency 20 KHz and amplitude level 70%) at 15 °C for 2 min. Significant increase (P < 0.05) was observed in total carotenoids, lycopene and lutein in blanched samples, however, this increase was more in simultaneously blanched and sonicated samples. Additionally, highest increase was observed in all these pigments as a result of combined treatment of acid blanching and sonication. Sucrose, glucose, fructose, chlorogenic acid and mineral elements (Na and K) were decreased significantly in all blanched samples while increased significantly (P < 0.05) in all sonicated samples. Significant decrease was observed in some minerals (P and Mg), total plate count, yeast and mold in all samples treated with blanching and sonication but this decrease was more in samples treated with acid blanching and sonication. The results suggest that combined treatment of blanching and sonication may successfully be employed for processing of carrot juice to improve quality. [Copyright &y& Elsevier]

Highlights: [•] Sonication could enhance the individual polyphenolic compounds of apple juice. [•] It could improve the sugar contents, some mineral elements and total carotenoids. [•] Sonication did not affect the total anthocyanins and electrical conductivity. [•] Sonication showed a potential to enhance the phytonutrients of apple juice. [ABSTRACT FROM AUTHOR]

Fresh apple juice treated with ultrasound (for 0, 30, 60 and 90min, at 20°C, 25kHz frequency) was evaluated for different physico-chemical, Hunter color values, cloud value, antioxidant capacity, scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical, ascorbic acid, total phenolics, flavonoids, flavonols and microbial characteristics. No significant effect of sonication was observed on pH, total soluble solids (°Brix) and titratable acidity of apple juice. Sonication significantly improved ascorbic acid, cloud value, phenolic compounds, antioxidant capacity, DPPH free radical scavenging activity and differences in Hunter color values. Moreover, significant reduction in microbial population was observed. Findings of the present study suggested that sonication treatment could improve the quality of apple juice. It may successfully be employed for the processing of apple juice with improved quality and safety from consumer’s health point of view. [ABSTRACT FROM AUTHOR]