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Acid value (AV) serves as an important indicator to assess the quality of oil, which can be used to judge the deterioration of edible oil. In order to realize the quantitative prediction of the AV of camellia seed oil, which was made from camellia oleifolia, hyperspectral data of 168 camellia seed oil samples were collected using a hyperspectral imaging system, which were related to their AV content measured via classical chemical titration. On the basis of hyperspectral full wavelengths, characteristic wavelengths, and fusing spectral and image features, the quantitative prediction AV models for camellia seed oil were established. The results demonstrating the 2Der-SPA-GLCM-PLSR model fusing spectral and image features stood out as the optimal choices for the AV prediction of camellia seed oil, with the correlation coefficient of calibration set ( R c 2 ) and the correlation coefficient of prediction set ( R p 2 ) at 0.9698 and 0.9581, respectively. Compared with those of 2Der-SPA-PLSR, the R c 2 and R p 2 were improved by 2.11% and 2.57%, respectively. Compared with those of 2Der-PLSR, the R c 2 and R p 2 were improved by 5.02% and 5.31%, respectively. Compared with the model based on original spectrum, the R c 2 and R p 2 were improved by 32.63% and 40.11%, respectively. After spectral preprocessing, characteristic wavelength selection, and fusing spectral and image features, the correlation coefficient of the optimal AV prediction model was continuously improved, while the root mean square error was continuously decreased. The research demonstrated that hyperspectral imaging technology could precisely and quantitatively predict the AV of camellia seed oil and also provide a new environmental method for detecting the AV of other edible oils, which is conducive to sustainable development. [ABSTRACT FROM AUTHOR]

This paper proposed a flexible pressure sensor based on poly(dimethylsiloxane) nanostructures film and report an efficient, simple, and low-cost fabrication strategy via soft nanoimprint lithography. The pressure sensor can convert external pressure or mechanical deformation into electrical signal to detect pressure and strain changes based on the coupling of triboelectrification and electrostatic induction. To enhance the performance of the pressure sensor, it consists of sub-500 nm resolution on the surface of elastic poly(dimethylsiloxane) sensitive layer and an indium tin oxide electrode thin film. When the pressure applied on the nanostructures layer, triboelectrostatic charges are induced. In the experiment, it measures up to sensitivity of 0.8 V/kPa at frequency of 5 Hz. This study results in potential applications such as wearable smart devices and skin-attachable diagnostics sensing systems.

This paper investigates how returnees' repatriation speed and irregularity affect FDI knowledge spillovers. Using a unique dataset of high-tech Chinese firms located in Zhongguancun Science Park in Beijing from 2007 to 2013, we find that returnees are vital in improving local firms' absorptive capacity and disseminating FDI externalities. Our empirical results show that returnees' high repatriation speed positively contributes to the local absorption of FDI knowledge spillovers, whereas repatriation irregularity dampens it. This research highlights the time-based attributes of returnees' repatriation as a new factor of absorptive capacity when learning from FDI knowledge. It thus provides a more integrated viewpoint on the relationship between returnees and FDI spillovers. Our findings have important implications for policymakers and practitioners. [ABSTRACT FROM AUTHOR]

Malignant peripheral nerve sheath tumor (MPNST) is a spindle cell sarcoma originating from peripheral nerves or showing differentiation of nerve sheath components. Primary MPNST of the stomach is an extremely rare neoplasm with only a few published reports in the literature. We present the case of a 58-year-old male patient with MPNST in the stomach. The patient was admitted due to upper abdomen discomfort. Gastroscopy revealed a huge ulcer lesion in the stomach, and biopsy revealed a spindle cell malignant neoplasm. No other specific findings were found in the whole-body imaging examination. Subtotal gastrectomy was performed. Histologically, an ulcer-type, push-infiltrating mass composed of dense, woven-like spindle cells with frequent mitosis could be seen. In immunohistochemistry, the tumor cells were negative for expression of H3K27 trimethylation (H3K27me3), keratin (AE1/AE3), epithelial membrane antigen (EMA), CD34, KIT, DOG1 (ANO1), S-100, SOX10, smooth muscle actin, desmin, myogenin, MDM2, CDK4, P16 (CDKN2A) and SS18-SSX (SS18::SSX). Primary MPNST of the stomach was diagnosed based on histological and immunohistochemical results. During the 2.5 years follow-up period after surgery, no recurrence was observed. [ABSTRACT FROM AUTHOR]

In this paper, a design method for a multiwavelength photon sieve is described based on a random-area-divided approach, where the whole aperture of a multiwavelength imaging photon sieve is divided into multiple discrete spaces corresponding to the number of the selected working wavelengths. The micropinhole distribution in each discrete space can be calculated for the defined wavelength with one fixed focal length in terms of the normal design for photon sieve. A three-wavelength photon sieve was designed and fabricated in the lab, and its imaging properties are analyzed in the experimental optical system with satisfactory results. OCIS codes: 050.1970, 220.4000, 350.3950, 110.4234.

An aperiodic mask design method for fabricating a microlens array with an aspherical profile is proposed. The nonlinear relationship between exposure doses and lens profile is considered, and the select criteria of quantization interval and fabrication range of the method are given. The mask function of a quadrangle microlens array with a hyperboloid profile used in the infrared was constructed by using this method. The microlens array can be effectively fabricated during a one time exposure process using the mask. Reactive ion etching was carried out to transfer the structure into the substrate of germanium. The measurement results indicate that the roughness is less than 10 nm (pv), and the profile error is less than 40 nm (rms). OCIS codes: 220.4000, 080.3630, 080.3620.

The paper describes the development and characterization of analytical properties of quantum dot-based probes for enzymatic activity and for screening enzyme inhibitors. The luminescent probes are based on fluorescence resonance energy transfer (FRET) between luminescent quantum dots that serve as donors and rhodamine acceptors that are immobilized to the surface of the quantum dots through peptide linkers. Peptide-coated CdSe/ZnS quantum dots were prepared using a one-step ligand exchange process in which RGDC peptide molecules replace trio-ctylphosphine oxide (TOPO) molecules as the capping ligands of the quantum dots. The peptide molecules were bound to the surface of the CdSe/ZnS quantum dots through the thioi group of the peptide cysteine residue. The peptide-coated quantum dots were labeled with rhodamine to form the FRET probes. The emission quantum yield of the quantum dot FRET probes was 4-fold lower than the emission quantum yield of TOPO-capped quantum dots. However, the quantum dot FRET probes were sufficiently bright to enable quantitative enzyme and enzyme inhibition assays. The probes were used first to test the enzymatic activity of trypsin in solution based on FRET signal changes of the quantum dot-based enzymatic probes in the presence of proteolytic enzymes. For example, exposure of the quantum dot FRET probes to 500 [micro]g/mL trypsin for 15 min resulted in 60% increase in the photoluminescence of the quantum dots and a corresponding decrease in the emission of the rhodamine molecules. These changes resulted from the release of rhodamine molecules from the surface of the quantum dots due to enzymatic cleavage of the peptide molecules. The quantum dot FRET-based probes were used to monitor the enzymatic activity of trypsin and to screen trypsin inhibitors for their inhibition efficiency.