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To instruct the production of millet porridge, the effect of cooking methods on flavor and texture of millet porridge was investigated. A total of 91 volatiles were detected and most volatile compounds decreased with cooking time, e.g. alcohols. The esters as major volatiles had a high content in electric rice cooker (IC). Multiple chemometric results indicated that volatiles from different cooking methods were distinguished respectively. Texture analysis indicated that the hardness of millet porridge prepared in IC had a more dominant decrease trend than electromagnetic oven and the electric pressure cooker before 40 min. In conclusion, different cooking methods had a more significant influence on the volatiles than cooking time, while the texture is opposite. The comprehensive sensory score reached its peak in IC-30 min. The comprehensive sensory scores of IC and EC decreased with the prolongation of cooking time. This study helps to improve the sensory attributes of millet porridge.

To investigate the optimal processing of maize porridge, the volatile compounds and texture under different cooking methods and time have been studied. A total of 51 volatile compounds were identified in maize porridge. Notably, the major volatiles, aldehydes and esters exhibited a relatively high content in electric pressure cooker (EPC), and esters tend to significantly increase after cooking. Among aldehydes, nonanal and hexanal played a great role in flavor due to their relatively high content. Volatile compounds of maize porridge in different cooking methods could be clearly distinguished by multiple chemometrics. Furthermore, texture analysis revealed that almost all the indicators in the EPC can reach the lowest value at 60 min. To summarize, different cooking methods had a more significant influence on the volatile compounds and texture compared to time. This study helps to improve the sensory attributes of maize porridge, and thus contributes to healthier and more sustainable production.

Abstract The conjugate shift differential method, based on Fourier transforms, is critical for surface error testing of high-precision optical elements. However, this common approach is also prone to periodic spectrum loss. As such, this paper proposes conjugate double shift differential (CDSD) absolute testing, which can effectively compensate for spectrum loss and achieve accurate wavefront reconstructions. Spectrum loss in the single shift differential method is analyzed through a study of the Fourier reconstruction process. A calculation model for the proposed CDSD method is then established and constraint conditions for shift quantities are provided by analyzing double shear effects observed in transverse shear interference. Finally, the reconstruction accuracies of various spectrum compensation methods are compared. Results showed that spectrum loss became more evident with increasing shift amounts. However, the CDSD method produced the smallest measurement error compared with conventional direct zero filling and adjacent point averaging, suggesting our approach could effectively improve absolute shape measurement accuracy for planar optical elements.

At present, the vascular grafts used in clinic are mainly autologous blood vessels, but they often face the dilemma of no blood vessels available due to limited sources. However, synthetic blood vessels made of polytetrafluoroethylene (ePTFE), which is commonly used in clinic, are prone to thrombosis and intimal hyperplasia, and the long-term patency rate is poor, so its effectiveness is severely limited, which is far from meeting the clinical needs. With the development of nano-materials, stem cells and 3D bio-printing technology, people began to explore the preparation of new endothelialized vascular grafts through this technology. Nano-peptide materials have excellent biocompatibility, can be compounded with different bioactive molecules, and have unique advantages in cultivating stem cells. It has been reported that self-assembled nano-polypeptide hydrogel was successfully constructed, mesenchymal stem cells were correctly isolated and cultured, and their transformation into blood vessels was studied. It was confirmed that the 3D bio-printed nano-polypeptide hydrogel tissue ADMSCs still had strong vascular endothelial differentiation ability. The application of mesenchymal stem cells and nano-polypeptide hydrogel in tissue engineering blood vessels has gradually become a research hotspot, and it is expected to develop a new type of transplanted blood vessel that meets the physiological functions of human body in terms of vascular endothelialization, cell compatibility and histocompatibility, so as to realize the customized and personalized printing of the endothelialized transplanted blood vessel according to the shape of the target blood vessel, which has attractive prospects and far-reaching social and economic benefits.

Understanding the surface recombination property of semiconductor materials is beneficial for improving the performance of optoelectronic devices. In this paper, differential photocarrier radiometry (PCR) is carried out to investigate the evolution of the surface recombination velocities of silicon wafers induced by laser irradiation. The PCR signal and the surface recombination velocities were found to be strongly dependent on the quality of the wafer surface and the duration of laser irradiation. The native oxide surface was more susceptible to laser irradiation than the Al2O3 passivated surface due to more surface defects being annealed. A surface-defect annealing model was used to explain the transient behavior of the PCR signal and the surface recombination velocity.

A novel preprocessing method based on a modified U-NET is proposed for single interference fringes. The framework is constructed by introducing spatial attention and channel attention modules to optimize performance. In this process, interferometric fringe maps with an added background intensity, fringe amplitude, and ambient noise are used as the input to the network, which outputs fringe maps in an ideal state. Simulated and experimental results demonstrated that this technique can preprocess single interference fringes in ~1 microsecond. The quality of the results was further evaluated using the root mean square error, peak signal-to-noise ratio, structural similarity, and equivalent number of views. The proposed method outperformed U-NET, U-NET++, and other conventional algorithms as measured by each of these metrics. In addition, the model produced high-quality normalized fringes by combining objective data with visual effects, significantly improving the accuracy of the phase solutions for single interference fringes.

The mirror component is one of the most critical components in the space remote sensing payload, and the performance of its support essentially determines the imaging quality of the system. Mirror components need to have high face shape accuracy, high reliability, and high stability. In this paper, taking the square mirror with the size of 550 mm × 450 mm as an example, we chose the Ultra-Low-Expansion Glass (Corning) as the mirror blank material, and through in-depth research on the principle of the three-point backside support and the engineering realization, we designed a three-point backside flexible support structure applied to the space mirror component. The design results were testified by simulation analysis; the results showed that with the mirror’s weight of 13.2 kg, the surface density can reach 48.5 kg/m2. For each gravity acceleration of 1 g, within the temperature range from 16 to 24 °C, carrying a forced displacement of 5 μm, the RMS value of the mirror component can reach 1/55λ (λ = 632.8 nm), which meets the requirement of high face shape accuracy of the mirror component in space. Finally, the mechanical test was carried out on the assembled mirror component, and the intrinsic frequencies of three directions of the mirror component were obtained through the test: 173.8 Hz, 176.4 Hz and 271.5 Hz, respectively. The changes of the mirror and its support structure were all less than 5″ after the 8 g sinusoidal vibration test and the 5.66 g random vibration test, which indicates that the flexible support structure meets the requirements of the high reliability of the space remote sensing loads and the high accuracy of the space mirror component. It shows that the flexible support structure meets the high reliability and high stability requirements of space remote sensing loads. The theoretical data and test results in this research can provide theoretical references for mirror components of the same size and type.

The olive vegetable is popular food owing to its unique flavor. This study innovatively used headspace-gas chromatography-ion mobility spectrometry to evaluate olive vegetables' volatiles under different conditions. A total of 57 volatile compounds were determined from olive vegetables, including 30 aldehydes, 8 ketones, 5 alcohols, 2 esters, 8 hydrocarbons, 1 furans, 3 sulfur compounds. The PCA distinguished the olive vegetable stored at different conditions by volatiles. The gallery plot showed that olive vegetables stored at 4 °C for 21 d produced more limonene, which had a desirable fruity odor. The (E)-2-octenal, (E)-2-pentenal, (E,E)-2,4-heptadienal, 5-methylfurfural, and heptanal in fresh olive vegetables were lowest and increased with storage time. Furthermore, the change of volatiles was the least when the olive vegetable was stored at 0 °C. This study can provide theoretical bases for improving the flavor quality of olive vegetables and developing traditional food for standardized industrial production.

In this paper, we propose a measurement method of micro-optical elements with parallel phase-shifting digital holographic phase imaging. This method can record four phase-shifting holograms with a phase difference of π/2 in a single shot and correct the pixel mismatch error of the polarization camera using a bilinear interpolation algorithm, thereby producing high-resolution four-step phase-shifting holograms. This method reconstructs the real phase information of the object to be measured through a four-step phase-shifting algorithm. The reproduced image eliminates the interference of zero-order images and conjugate images, overcoming the problem that traditional phase-shifting digital holography cannot be measured in real time. A simulation analysis showed that the relative error of this measurement method could reach 0.0051%. The accurate surface topography information of the object was reconstructed from an experimental measurement through a microlens array. Multiple measurements yielded a mean absolute error and a mean relative error for the vertical height of the microlens array down to 5.9500 nm and 0.0461%, respectively.

For a fiber optic gyroscope, thermal deformation of the fiber coil can introduce additional thermal-induced phase errors, commonly referred to as thermal errors. Implementing effective thermal error compensation techniques is crucial to addressing this issue. These techniques operate based on the real-time sensing of thermal errors and subsequent correction within the output signal. Given the challenge of directly isolating thermal errors from the gyroscope’s output signal, predicting thermal errors based on temperature becomes necessary. To establish a mathematical model correlating the temperature and thermal errors, this study measured synchronized data of phase errors and angular velocity for the fiber coil under various temperature conditions, aiming to model it using data-driven methods. However, due to the difficulty of conducting tests and the limited number of data samples, direct engagement in data-driven modeling poses a risk of severe overfitting. To overcome this challenge, we propose a modeling algorithm that effectively integrates theoretical models with data, referred to as the TD-model in this paper. Initially, a theoretical analysis of the phase errors caused by thermal deformation of the fiber coil is performed. Subsequently, critical parameters, such as the thermal expansion coefficient, are determined, leading to the establishment of a theoretical model. Finally, the theoretical analysis model is incorporated as a regularization term and combined with the test data to jointly participate in the regression of model coefficients. Through experimental comparative analysis, it is shown that, relative to ordinary regression models, the TD-model effectively mitigates overfitting caused by the limited number of samples, resulting in a substantial 58% improvement in predictive accuracy.

To address the complexity and low detection accuracy issues in the intrinsic frequency detection process of fiber optic gyroscopes, a highly precise automatic measurement method based on optimal projection approximation is proposed. Building upon the digital closed-loop fiber optic gyroscope hardware circuit, this method generates a frequency-adjustable square wave with a 25% duty cycle through field-programmable gate array (FPGA) fractional division. Subsequently, it calculates the difference between the high and low levels of the sign bits of the modulated optical intensity signal sampled by the analog-to-digital converter (ADC). This yields an error signal related to the modulation frequency and intrinsic frequency. The modulation frequency is then approximated using the nearest projection of this error signal, thereby achieving automatic detection of the fiber optic gyroscope’s intrinsic frequency. The experimental results indicate that this method, requiring no external auxiliary equipment, enables rapid and highly accurate measurement of the intrinsic frequency of the fiber optic gyroscope. The measurement of intrinsic frequency takes approximately 300 milliseconds, achieving a measurement accuracy of up to 0.001 Hz.

Bischofia polycarpa seed oil is rich in nutrition and positively affects on human health. We analyzed and compared the chemical compositions, antioxidant activities, and quality characteristics of Bischofia polycarpa seed oils using different solvents and cold-pressing. Hx: Iso (n-hexane/isopropanol, 3:2 v/v) had the highest lipid yield (35.13 %), while Folch (chloroform/methanol, 2:1 v/v) had the highest linolenic acid (50.79 %), LnLnLn (43.42 %), and LnLnL (23.43 %). Tocopherols (2108.99 mg/kg) were extracted most efficiently with Folch, whereas phytosterols (3852.97 mg/kg) and squalene (55.21 mg/kg) were extracted most efficiently with petroleum ether. Although the lower phytosterol was obtained using isopropanol, the polyphenol content (271.34 mg GAE/kg) was significantly higher than other solvents, showing the best antioxidant ability. Additionally, polyphenols were observed to be the most significant factor predicting antioxidant activity from the correlation analysis. The above information can provide a useful reference for manufacturers to obtain satisfactory Bischofia polycarpa seed oil.

Green plum is popular due to its tasty flavor and nutritional benefits. This study investigated the volatiles of oils extracted from the green plum seed using the headspace-gas chromatography-ion mobility spectrometry. A total of 42 volatiles were identified in the oil of green plum seed kernel and shell. By principal component analysis, a distinct separation between the seed kernel oil and shell oil was observed. The gallery plot showed that seed kernel oil had more desirable flavor compounds, such as ethyl acetate, 1-pentanol, 2-pentylfuran, and 2-heptanone. However, seed shell oil contained more alkenals with a fatty odor and acetic acid with a pungent odor. The green plum seed oils were rich in oleic acid (>45 g/100 g), linoleic acid (>35 g/100 g), and minor bioactive components, i.e., tocopherol, phytosterol, and squalene. The shell oil had more total tocopherol (95.35 mg/kg) and β-Sitosterol (80.70 %) compared to kernel oil. Therefore, green plum seed oil can be sustainably used as an edible oil.

In order to reduce the weight of optical elements in space remote sensors while increasing their stiffness, this paper takes an off-axis system secondary mirror as an example to design a square mirror with a size of 500 mm × 500 mm. The mirror adopts ultra-low expansion glass as the raw material. The paper proposed a lightweight form of gradual reinforcement and conducted the mirror assembly simulation analysis. The analysis results show that the weight of the lightweight mirror is 13.6 kg, and the surface density can reach 54.4 kg/m2. Under the circumstances of 1 g gravity and the temperature change of 15 °C~25 °C, the surface shape accuracy of the mirror assembly can reach 1/90λ (λ = 632.8 nm). Through the final testing, the first-order intrinsic frequency of the reflex mirror components is 167.8 Hz. The gap between the test results and the theoretical simulation results is less than 3%, which proves that the mirror assembly in the lightweight form of gradual reinforcement fully meets the index requirements and can provide a theoretical reference for the assembly of a mirror of similar size and type.

As an interesting technique that allows data extraction and image recovery without any loss, reversible data hiding in encrypted images is an area of great concern in the field of information security. In this paper, a new reversible data hiding method with high embedding capacity is proposed based on hybrid prediction and Huffman coding. The combination of two embedding mechanisms is innovatively designed to improve the embedding capacity according to different parts of the original image, i.e., the most significant bit-plane and the remaining seven bit-planes. In the first part of this method, the prediction value of each pixel is obtained by calculating the average value of its two neighboring pixels, and all of the most significant bits can be vacated to accommodate additional data. In the second part, the prediction value of each pixel is calculated using the median edge detector predictor, on which the tag map is built. Then, Huffman coding is used to compress the tag map so that a large amount of vacant space is obtained. Finally, the secret data can be embedded into the vacated space by directly using bit substitution. Compared with some recently reported methods, experimental results and analysis have demonstrated that an original image with high visual symmetry/quality can be recovered. Also, larger embedding capacity can be achieved, such as 3.3894 bpp and 3.2824 bpp, for BOSSBase and BOWS2 databases, respectively.

For precise optical elements, the size of in-surface defects is at the nanometer scale. When incident light illuminates in-surface defects on optical elements, strong diffraction and scattering effects are produced, and this greatly reduces the beam quality in optical systems. In this study, a three-dimensional model of the in-surface defects of K9 optical components was established. On this basis, a theoretical model of electromagnetic scattering between the defect and the incident and scattering fields was constructed. The 4 × 4-order scattering Mueller matrix light field distributions of incident light modulated by different-sized defects were obtained by numerical simulations, and the influencing factors were analyzed. These simulations provide a theoretical basis and a reference for the manufacture of precision optical elements and a scale calibration for surface quality detection methods.

High efficiency and accuracy of semi-global matching (SGM) make it widely used in many stereo vision applications. However, SGM not only struggles in dealing with pixels in homogeneous area, but also suffers from streak artifacts. In this paper, we propose a novel omni-directional SGM (OmniSGM) with a cost volume update scheme to aggregate costs from paths along all directions and to encourage reliable information to propagate across entire image. Specifically, we perform SGM along four tree structures, namely trees in the left, right, top and bottom of root node, and then fuse the outputs to obtain final result. The contributions of pixels on each tree can be recursively computed from leaf nodes to root node, ensuring our method has linear time computational complexity. Moreover, An iterative cost volume update scheme is proposed using aggregated cost in the last pass to enhance the robustness of initial matching cost. Thus, useful information is more likely to propagate in a long distance to handle the ambiguities in low textural area. Finally, we present an efficient strategy to propagate disparities of stable pixels along the minimum spanning tree (MST) for disparity refinement. Extensive experiments in stereo matching on Middlebury and KITTI datasets demonstrate that our method outperforms typical traditional SGM-based cost aggregation methods.

Objective: This study aimed to observe the cell growth status and multidirectional differentiation ability in a 3D-bioprinted tissue model of self-assembled nanopeptides and human adipose-derived mesenchymal stem cells (Ad-MSCs).Methods: Primary Ad-MSCs were isolated, cultured, and identified by flow cytometry. Tissue models were printed via 3D bioprinting technology using a “biological ink” consisting of a mixed solution of self-assembled nanopeptides and Ad-MSCs. Ad-MSCs were induced into osteogenic, adipogenic, and endothelial differentiation and compared with the control groups by staining.Results: The nanopeptide fiber was 10–30 nm in diameter and 200–500 nm in length under the atomic-force microscope. It had the characteristics of nano-scale materials. Flow cytometry showed that the isolated and cultured cells were positive for CD29 (98.51%), CD90 (97.87%), and CD166 (98.32%) but did not express CD31 (1.58%), CD34 (2.42%), CD45 (2.95%), or human leukocyte antigen (HLA)-DR (0.53%), consistent with the immunophenotype of Ad-MSCs. Then, a tissue model was printed using the biological ink, followed by induction of differentiation of Ad-MSCs within the tissue model. Alizarin red S staining showed the formation of calcium nodules in the osteogenesis induction experimental group, and oil red O stained lipid droplets in Ad-MSCs in the adipogenesis induction experimental group, whereas the two control groups were not stained.Conclusion: Ad-MSCs from primary cultures have the characteristics of stem cells. Self-assembled nanopeptide hydrogel is a good tissue engineering material that can serve as an extracellular matrix. Ad-MSCs in the 3D-printed tissue model using a biological ink consisting of a mixed solution of self-assembled nanopeptides and Ad-MSCs grew well and still had strong differentiation ability.

To solve the coherent noise problem of an interference image, the method of a rotating diffuser was adopted to change the coherence of a beam to reduce the noise of the interference system. The relationship between the speed of the diffuser and the signal-to-noise ratio (SNR) of the fringe contrast system was simulated to obtain the diffuser control parameters needed for the best interference fringe state. The fringe contrast of each image and the SNR of the system were analyzed. The results showed that the increased speed of the diffuser reduced the contrast of the interference image to a certain extent, but the increased speed also effectively improved the SNR and facilitated the subsequent interference image processing. Due to the coherent noise in the interferometric system, the method of the rotated diffuser reduced the coherence of the light beam to suppress the noise of the interference image. By analyzing the coherent noise reduction characteristics of the rotated diffuser with different surface roughnesses, the relationship between the surface roughness and the noise contrast for different rotation speeds was simulated, and the effective roughness range with the noise reduction effect was selected. A noise reduction system was built based on Fizeau interference, and the noise contrast of the interference image was collected and calculated. The effective range of σh/λ was 0.2–0.5 when the rotation speed was 10 r/s, while the effective range of σh/λ was 0.4–0.6 when the rotation speed was 100 r/s. The experimental results showed that the surface roughness and wavelength ratio σh/λ of the rotated diffuser increased when the noise contrast tended toward 1, but the effective range of the surface roughness decreased with the increase of the rotational speed of the diffuser.

Modern optical engineering requires increasingly sophisticated interferometry methods capable of conducting subnanometer scale measurements of the large aperture, high-precision optical component surfaces. However, the accuracy of interferometry measurement is limited to the accuracy with which the surface of the reference mirror employed in the interferometer system is known, and the influence of gravity-induced deformation cannot be ignored. This is addressed in the present work by proposing a three-flat testing method based on multiposition rotation interference absolute surface measurement technology that combines the basic theory of N-position rotation with the separability of surface wavefront functions into sums of even and odd functions. These functions provide the rotational symmetric components of the wavefront, which then enables the absolute surface to be reconstructed based on the N-position rotation measurements. In addition, we propose a mechanical clamping combined with computational method to compensate for the gravity-induced deformations of the flats in the multiposition rotation absolute measurements. The high precision of the proposed absolute surface measurement method is demonstrated via simulations. The results of laboratory experiments indicate that the combination compensation method provides the high-precision surface reconstruction outcomes. The present work provides an important contribution for supporting the interferometry measurement of large aperture, high-precision optical component surfaces.

A novel optical multiple-image hiding method is proposed based on two cascaded free-space propagation transforms in this paper. With the use of the structured phase mask in the phase retrieval algorithm, a plain image is encoded to only one statistically independent phase-only mask. All retrieved phase masks are integrated into the noise-like ciphertext by using the phase mask multiplexing technique. When reconstructing an original plain image, the architecture of double random phase encoding system is directly adopted, where the structured phase mask and the corresponding decryption key mask are located at determined positions along the axis of propagation. Besides the propagation distances, the optical parameters such as wavelength, focal length, and topological charge of the structured mask are considered as the security keys to expand the key space. To the best of our knowledge, it is the first report on employing the structured phase mask in the process of phase retrieval algorithm, which can enhance the level of security greatly. Simulation results have been given to verify the feasibility and robustness of the proposed scheme.

This study proposes a novel wavelength-tuning common-path digital holographic microscopy technique for quantitative phase imaging of functional micro-optics components. The proposed technique is immune to vibration and can reduce system error. In the proposed configuration, a parallel glass plate was inserted into the light path to create two identical test beams, which passed through a specially designed window filter. In this process, one beam serves as the object beam, while the other is diffracted to produce an ideal spherical wave front (the reference beam). A wavelength tunable laser was used as the light source to generate phase-shifting digital holograms. Structural information for the functional micro-optics components was then extracted using a classical four-step phase-shift algorithm. The viability of the proposed technique was assessed by measuring a micro-optics array.

This paper proposes a real-time compensated pentaprism scanning wavefront detection method to achieve real-time compensation for scanning errors occurring during prism movement along a guide rail. The method is based on existing pentaprism scanning wavefront detection technology and it is realized by applying self-collimation-based three-dimensional error compensation. Using theoretical and data analyses of a detection experiment, the reliability of the optimized pentaprism scanning detection method is verified, thus effectively ensuring the reasonable estimation of the interferometry surface measurement uncertainty.