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High-complexity network models are challenging to execute on agricultural robots with limited computing capabilities in a large-scale pineapple planting environment in real time. Traditional module replacement often struggles to reduce model complexity while maintaining stable network accuracy effectively. This paper investigates a pineapple detection framework with a YOLOv7-tiny model improved via pruning and a lightweight backbone sub-network (the RGDP-YOLOv7-tiny model). The ReXNet network is designed to significantly reduce the number of parameters in the YOLOv7-tiny backbone network layer during the group-level pruning process. Meanwhile, to enhance the efficacy of the lightweight network, a GSConv network has been developed and integrated into the neck network, to further diminish the number of parameters. In addition, the detection network incorporates a decoupled head network aimed at separating the tasks of classification and localization, which can enhance the model's convergence speed. The experimental results indicate that the network before pruning optimization achieved an improvement of 3.0% and 2.2%, in terms of mean average precision and F1 score, respectively. After pruning optimization, the RGDP-YOLOv7-tiny network was compressed to just 2.27 M in parameter count, 4.5 × 10 9 in computational complexity, and 5.0MB in model size, which were 37.8%, 34.1%, and 40.7% of the original YOLOv7-tiny network, respectively. Concurrently, the mean average precision and F1 score reached 87.9% and 87.4%, respectively, with increases of 0.8% and 1.3%. Ultimately, the model's generalization performance was validated through heatmap visualization experiments. Overall, the proposed pineapple object detection framework can effectively enhance detection accuracy. In a large-scale fruit cultivation environment, especially under the constraints of hardware limitations and limited computational power in the real-time detection processes of agricultural robots, it facilitates the practical application of artificial intelligence algorithms in agricultural engineering. [ABSTRACT FROM AUTHOR]

The Inconel 718 superalloy demonstrates the potential to fabricate high-temperature components using additive manufacturing. However, additively manufactured Inconel 718 typically exhibits low strength, necessitating post-heat treatments for precipitate strengthening. This study investigated the microstructures and mechanical properties of the Inconel 718 superalloy fabricated via laser powder bed fusion. The room-temperature and high-temperature tensile properties of the Inconel 718 alloy samples following various post-heat treatments were evaluated. The results indicate that the as-built samples exhibited columnar grains with fine cell structures. Solution treatment resulted in δ phase formation and grain recrystallization. Subsequent double aging led to finely distributed nanoscale γ′ and γ″ particles. These nanoscale particles provided high strength at both room and high temperatures, resulting in a balanced strength and ductility comparable to the wrought counterpart. High-temperature nanoindentation analyses revealed that the double-aging samples exhibited very high hardness and low creep rates at 650 °C. [ABSTRACT FROM AUTHOR]

The color features of strawberries at different growth stages vary slightly and occluded during growth. To address these challenges, this study proposes a lightweight multi-stage detection method based on You Only Look Once version 7-tiny (YOLOv7-tiny) for strawberries in complex environments. First, the size of the model is reduced by replacing the ordinary convolution of the neck network used for deep feature extraction and fusion with lightweight Ghost convolution. Then, by introducing the Coordinate Attention (CA) module, the model's focus on the target detection area is enhanced, thereby improving the detection accuracy of strawberries. The Wise Intersection over Union (WIoU) loss function is integrated to accelerate model convergence and enhance the recognition accuracy of occluded targets. The advanced Adaptive nesterov momentum algorithm (Adan) is utilized for gradient descent, processing averaged sample data. Additionally, considering the small size of strawberry targets, a detection head specifically for small targets is added, performing detection on a 160 × 160 × 64 feature map, which significantly improves the detection performance for small strawberries. Experimental results demonstrate that the improved network model achieves an m A P @ 0.5 of 88.2% for multi-stage strawberry detection, which is 2.44% higher than the original YOLOv7-tiny algorithm. Meanwhile, G F L O P s and P a r a m s are reduced by 1.54% and 12.10%, respectively. In practical detection and inference, the improved model outperforms current mainstream target detection models, enabling a quicker and more accurate identification of strawberries at different growth stages, thus providing technical support for intelligent strawberry picking. [ABSTRACT FROM AUTHOR]

Titanium parts fabricated by additive manufacturing, i.e., laser or electron beam-powder bed fusion (L- or EB-PBF), usually exhibit columnar grain structures along the build direction, resulting in both microstructural and mechanical anisotropy. Post-heat treatments are usually used to reduce or eliminate such anisotropy. In this work, Ti-6Al-2Zr-1Mo-1V (TA15) alloy samples were fabricated by L-PBF to investigate the effect of post-heat treatment and load direction on the dynamic response of the samples. Post-heat treatments included single-step annealing at 800 °C (HT) and a hot isotropic press (HIP). The as-built and heat-treated samples were dynamically compressed using a split Hopkinson pressure bar at a strain rate of 3000 s−1 along the horizontal and vertical directions paralleled to the load direction. The microstructural observation revealed that the as-built TA15 sample exhibited columnar grains with fine martensite inside. The HT sample exhibited a fine lamellar structure, whereas the HIP sample exhibited a coarse lamellar structure. The dynamic compression results showed that post-heat treatment at 800 °C led to reduced flow stress but enhanced uniform plastic strain and damage absorption work. However, the HIP samples exhibited both higher stress, uniform plastic strain, and damage absorption work owing to the microstructure coarsening. Additionally, the load direction had a subtle influence on the flow stress, indicating the negligible anisotropy of flow stress in the samples. However, there was more significant anisotropy of the uniform plastic strain and damage absorption. The samples had a higher load-bearing capacity when dynamically compressed perpendicular to the build direction. [ABSTRACT FROM AUTHOR]

In this work, the effect of Mo on the microstructure and properties of Ni-Mo-Al2O3 coatings by cold spraying was studied. The microstructure, composition, hardness, wear resistance and chlorine salt corrosion resistance of the coatings were analyzed by a scanning electron microscope, EDS, X-ray diffractometer, 3D profilometer, microhardness tester and friction wear tester. The results show that the coatings have low porosity and a uniform structure. The addition of Mo can improve the hardness, electrical conductivity, wear resistance and chlorine salt corrosion resistance of the coating but reduce the deposition efficiency of the powder. In general, the 80Ni-10Mo-10Al2O3 coating has the best comprehensive performance, with a hardness of 270.17 HV, friction coefficient of 0.4171 and corrosion rate of 0.287 g/m2·h in molten chloride. [ABSTRACT FROM AUTHOR]

The low strength caused by the single FCC structure of the CrMnFeCoNi high entropy alloy (HEA) limits its application in the field of coating. Here, we prepared high-entropy alloy coatings of CrMnFeCoNi with different ZrC contents on Q235 steel by a plasma transferred arc process. The effects of ZrC on the microstructure and properties of the CrMnFeCoNi HEA coating were investigated by optical microscopy, scanning electron microscope, and X-ray diffraction and by employing a potensiostat/galvanostat. The results showed that ZrC mainly existed in the coatings as a second phase, having little influence on the main crystal structure and micromorphology of the CrMnFeCoNi HEA coating. The hardness of the CrMnFeCoNi HEA coating increased with the ZrC content. ZrC can effectively improve the corrosion resistance of the CrMnFeCoNi HEA coating. In a 1 mol/L NaCl solution with 4 wt% ZrC, the annual corrosion rate was only 5.997% of that of the HEA coating. Nevertheless, the improvement in the wear resistance of CrMnFeCoNi high-entropy alloy coatings was not apparent with the addition of ZrC. Consequently, the addition of ZrC to the FeCoCrNiMn high-entropy alloy coating holds promise for applications in corrosion resistance, particularly in oceanic environments. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) can effectively replace traditional processing methods to prepare parts with arbitrary complex shapes through layer-by-layer accumulation. However, SLM Ti-6Al-4V alloy typically exhibits low ductility and significant mechanical properties anisotropy due to the presence of acicular α′ martensite and columnar prior β grains. Post-heat treatment is frequently used to obtain superior mechanical properties by decomposing acicular α′ martensite into an equilibrium α + β phase. In this study, the microstructure and tensile properties of SLM Ti-6Al-4V alloy before and after various heat treatments were systematically investigated. The microstructure of the as-fabricated Ti-6Al-4V sample was composed of columnar prior β grains and acicular α′ martensite, which led to high strength (~1400 MPa) but low ductility (~5%) as well as significantly tensile anisotropy. The single heat treatment samples with lamellar α + β microstructure exhibited improved elongation to 6.8–13.1% with a sacrifice of strength of 100–200 MPa, while the tensile anisotropy was weakened. A trimodal microstructure was achieved through multi-step high-to-low-temperature (HLT) heat treatment, resulting in an excellent combination of strength (~1090 MPa) and ductility (~17%), while the tensile anisotropy was almost eliminated. The comprehensive mechanical properties of the HLT samples were superior to that of the conventional manufactured Ti-6Al-4V alloy. [ABSTRACT FROM AUTHOR]

In this study, a low-cost space mapping (SM) modeling method with mesh deformation is proposed for microwave components. In this approach, the coarse-mesh model with mesh deformation is developed as the coarse model, and the fine-mesh model is simulated as the fine model. The SM technique establishes the mapping relationship between the coarse-mesh model and the fine-mesh model. This approach enables us to combine the computational efficiency of the coarse model with the accuracy of the fine model. The automatic mesh deformation technology is embedded in the coarse model to avoid the discontinuous change in the electromagnetic response. The proposed model consisting of the coarse model and two mapping modules can represent the features of the fine model more accurately, and predict the electromagnetic response of microwave components quickly. The proposed mesh SM modeling technique is applied to the four-pole waveguide filter. The value for the training and test errors in the proposed model is less than 1%, which is lower than that for the ANN models and the existing SM models trained with the same data. Compared with HFSS software, the proposed model can save about 70% CPU time in predicting a set of 100 data. The results show that the proposed method achieves a good modeling accuracy and efficiency with few training data and a low computational cost. [ABSTRACT FROM AUTHOR]

Owing to the heterogeneity and incomplete information present in various domain knowledge graphs, the alignment of distinct source entities that represent an identical real-world entity becomes imperative. Existing methods focus on cross-lingual knowledge graph alignment, and assume that the entities of knowledge graphs in the same language are unique. However, due to the ambiguity of language, heterogeneous knowledge graphs in the same language are often duplicated, and relationship triples are far less than those of cross-lingual knowledge graphs. Moreover, existing methods rarely exclude noisy entities in the process of alignment. These make it impossible for existing methods to deal effectively with the entity alignment of domain knowledge graphs. In order to address these issues, we propose a novel entity alignment approach based on domain-oriented embedded representation (DomainEA). Firstly, a filtering mechanism employs the language model to extract the semantic features of entities and to exclude noisy entities for each entity. Secondly, a Structural Aggregator (SA) incorporates multiple hidden layers to generate high-order neighborhood-aware embeddings of entities that have few relationship connections. An Attribute Aggregator (AA) introduces self-attention to dynamically calculate weights that represent the importance of the attribute values of the entities. Finally, the approach calculates a transformation matrix to map the embeddings of distinct domain knowledge graphs onto a unified space, and matches entities via the joint embeddings of the SA and AA. Compared to six state-of-the-art methods, our experimental results on multiple food datasets show the following: (i) Our approach achieves an average improvement of 6.9% on MRR. (ii) The size of the dataset has a subtle influence on our approach; there is a positive correlation between the expansion of the dataset size and an improvement in most of the metrics. (iii) We can achieve a significant improvement in the level of recall by employing a filtering mechanism that is limited to the top-100 nearest entities as the candidate pairs. [ABSTRACT FROM AUTHOR]

In this paper, an improved empirical formula modeling method using neuro-space mapping (Neuro-SM) for coupled microstrip lines is proposed. Empirical formulas with correction values are used for the coarse model, avoiding a slow trial-and-error process. The proposed model uses mapping neural networks (MNNs), including both geometric variables and frequency variables to improve accuracy with fewer variables. Additionally, an advanced method incorporating simple sensitivity analysis expressions into the training process is proposed to accelerate the optimization process. The experimental results show that the proposed model with its simple structure and an effective training process can accurately reflect the performance of coupled microstrip lines. The proposed model is more compatible than models in existing simulation software. [ABSTRACT FROM AUTHOR]

Vision is an important way for unmanned mobile platforms to understand surrounding environmental information. For an unmanned mobile platform, quickly and accurately obtaining environmental information is a basic requirement for its subsequent visual tasks. Based on this, a unique convolution module called Multi-Scale Depthwise Separable Convolution module is proposed for real-time semantic segmentation. This module mainly consists of concatenation pointwise convolution and multi-scale depthwise convolution. Not only does the concatenation pointwise convolution change the number of channels, but it also combines the spatial features from the multi-scale depthwise convolution operations to produce additional features. The Multi-Scale Depthwise Separable Convolution module can strengthen the non-linear relationship between input and output. Specifically, the multi-scale depthwise convolution module extracts multi-scale spatial features while remaining lightweight. This fully uses multi-scale information to describe objects despite their different sizes. Here, Mean Intersection over Union (MIoU), parameters, and inference speed were used to describe the performance of the proposed network. On the Camvid, KITTI, and Cityscapes datasets, the proposed algorithm compromised between accuracy and memory in comparison to widely used and cutting-edge algorithms. In particular, the proposed algorithm acquired 61.02 MIoU with 2.68 M parameters on the Camvid test dataset. [ABSTRACT FROM AUTHOR]

Beta titanium (β-Ti) alloys have been widely used in aerospace and biomedical implants due to their specific strengths, low elastic modulus, and their resistance to corrosion. As β titanium alloy is a novel metastable, Ti-2Al-9.2Mo-2Fe (wt.%) alloy is essential to understand microstructural evolution and deformation behavior at room temperature to improve the strength–ductility balance. The deformation behavior and microstructural evolution of the Ti-2Al-9.2Mo-2Fe alloy during room-temperature deformation has been investigated via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI). It was found that the β-solution-treated alloy exhibited a single β phase with a lower β stability. However, the α/β-solution-treated alloy exhibited a layered structure, consisting of fine α + β grain layers and coarse β grain layers, and the β in the coarse grain layer had a lower stability, but the β in the fine grain layer had a higher stability owing to the coexistence of α. The β-solution-treated alloy was mainly deformed via {332}<113> deformation twinning, thus showing very high ductility; uniform elongation of approximately 35%. The α/β-solution-treated alloy was deformed via two mechanisms, namely {332}<113> deformation twinning in the coarse grain layers and dislocation slip in the fine grain layers. The α/β-solution-treated alloy exhibited high strength with a lower ductility due to the small amount of deformation twinning. [ABSTRACT FROM AUTHOR]

Due to the lack of appropriate experimental methods for imaging the evolution of the microstructure of materials at the growth conditions, our understanding of the physical behavior of crystal growth and defect formation during the vapor deposition growth of SiC crystals is still rather limited. In the present work, the vapor deposition growth of SiC crystal on a 4H-SiC substrate has been investigated by the molecular dynamics (MD) computer simulation method. Three different lattice planes of 4H-SiC ( (0001) , (11 2 - 0) and (1 - 100) ) were selected as the surface of the substrate, and three different temperatures for substrate (2200 K, 2300 K and 2400 K) were used in growth simulations. The characteristics of the formation of different polytypes of SiC and dislocations in the grown crystals were examined. The results show that the SiC crystals were grown by a subsurface nucleation and growth mode in the vapor deposition process. For substrates with (0001) plane as the surface, the 3C-SiC single crystal was obtained in the deposited thin film. For substrates with (11 2 - 0) or (1 - 100) plane as the surface, the 4H-SiC single crystal was obtained instead. The temperature of the substrate was found to have a significant effect on the dislocation density generated in the grown crystals. The mechanism for the formation of Frank partial dislocations during the growth of SiC crystals has been analyzed, for which the importance of the diffusivity of atoms on the surface layer in growth has been highlighted, and it gives a good explanation of the temperature effect on dislocation formation in the grown crystals. These results can be helpful for experimental vapor deposition growth of SiC single crystals and epitaxial layers of high quality. [ABSTRACT FROM AUTHOR]

Kitchen waste (KW) has high water content and organic matter, which has great potential for energy application, but how to treat it effectively has always been a difficult problem. In this study, the feasibility of transforming kitchen waste into hydrochar as a solid fuel to replace the primary energy by hydrothermal carbonization (HTC) is put forward. An experimental study of proportioned KW under HTC conditions (reaction temperature, residence time, liquid–solid ratio) is carried out by elemental analysis, industrial analysis, energy density calculation, and calorific value measurement. The results show that a proper extension of the residence time to 3.5 h at a liquid–solid ratio of 10 and a reaction temperature of 265 °C for the kitchen waste after HTC would result in a maximum calorific value of 30.933 MJ/Kg for the prepared hydrochar. The maximum ash content of hydrochar at a 265 °C reaction temperature is 3.94% < 10%, which is much lower than the standard of extra-low-ash coal, and the study shows that the hydrochar prepared from kitchen waste by HTC for combustion will greatly improve the combustion efficiency. The three types of kitchen waste under HTC conditions are compared with the three typical types of coal in China by the van Krevelen diagram. The results show that the combustion properties of hydrochar from kitchen waste prepared by the HTC method are better than those of lignite close to bituminous coal and can provide a theoretical basis for replacing primary energy in the future. Finally, by combining thermogravimetric analysis with mathematical modeling, it is calculated that the hydrochar of kitchen waste has a lower activation energy than those of other biomass, which can better facilitate the reaction. The experimental results further determine the feasibility of hydrochar as an alternative primary energy source and provide a theoretical basis for the future conversion of kitchen waste into hydrochar as a solid fuel through HTC. [ABSTRACT FROM AUTHOR]

Carboxylesterases (CEs) play important physiological roles in the human body and are involved in numerous cellular processes. Monitoring CEs activity has great potential for the rapid diagnosis of malignant tumors and multiple diseases. Herein, we developed a new phenazine-based "turn-on" fluorescent probe DBPpys by introducing 4-bromomethyl-phenyl acetate to DBPpy, which can selectively detect CEs with a low detection limit (9.38 × 10−5 U/mL) and a large Stokes shift (more than 250 nm) in vitro. In addition, DBPpys can also be converted into DBPpy by carboxylesterase in HeLa cells and localized in lipid droplets (LDs), emitting bright near-infrared fluorescence under the irradiation of white light. Moreover, we achieved the detection of cell health status by measuring the intensity of NIR fluorescence after co-incubation of DBPpys with H2O2-pretreated HeLa cells, indicating that DBPpys has great potential applications for assessing CEs activity and cellular health. [ABSTRACT FROM AUTHOR]

Cobalt-based superalloys are common materials for the manufacturing of various components used in aerospace applications. Conventional cobalt-based superalloys with a unimodal grain structure generally exhibit low strength and ductility at high temperatures. A bimodal grain structure of a cobalt-based superalloy, Co–20Cr–15W–10Ni (CCWN), was designed to achieve both high strength and ductility at high temperatures. The deformation behavior and tensile properties of a CCWN alloy with unimodal fine-grain (FG), coarse-grain (CG), and bimodal (FG/CG) structures were investigated at 900 °C. The microstructures and substructures after high-temperature deformation were examined via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) to determine the deformation mechanisms. The microstructural observation showed that the bimodal grain structure consisted of FG and CG domains. During high-temperature deformation at 900 °C, the FG structure was mainly deformed by dynamic recrystallization (DRX), maintaining a similar FG structure. The CG structure was mainly deformed by DRV, resulting in a small amount of DRX grains and a large amount of dynamic recovery (DRV) grains. However, the bimodal grain structures were mainly softened via DRX and transformed into a new bimodal structure, ultrafine grain (UFG) and FG. The FG domains tended to deform via dislocations, and the CG domains via twinning. The high-temperature tensile tests revealed that the bimodal-structured alloy exhibited both higher strength and ductility than those of the alloy samples with unimodal FG or CG structure. This is associated with the newly developed UFG/FG structures in the bimodal grain-structured samples during high-temperature deformation. This work may provide new insight into the development of high-temperature alloys with bimodal grain structures. [ABSTRACT FROM AUTHOR]

This study looked into the thermo-mechanical properties and the recrystallization mechanisms of the Ti–5.5Cr–5Mo–5V-4Al–1Nb alloy (wt.%, Ti−65541). Hot compression experiments were conducted at two phase regions (740~950 °C) and strain rates from 0.001 to 1 s−1. The compressive strain–stress curves were corrected by the adiabatic heating effect. The Arrhenius model was established and provided a reliable prediction of the value of stress with a 0.992 correlation coefficient. The constructed processing map demonstrated that when the temperature rose and the strain rate fell, the power dissipation efficiency (η) showed a rising trend. By utilizing electron backscattered diffraction (EBSD), the microstructural evolution and deformation process were analyzed. It was possible to witness both continuous dynamic recrystallization (cDRX) and discontinuous dynamic recrystallization (dDRX). The dynamic recovery (DRV) and dDRX eventually replaced dDRX while η decreased. Moreover, the deformation band (DB) impeded re-crystallization in the low η area. This study can supply a relatively reliable processing interval for the new Ti−65541 alloy. [ABSTRACT FROM AUTHOR]

Due to the rapid development of the miniaturization and portability of electronic devices, the demand for polymer composites with high thermal conductivity and mechanical flexibility has significantly increased. A carbon nanotube (CNT)-graphene (Gr)/polydimethylsiloxane (PDMS) composite with excellent thermal conductivity and mechanical flexibility is prepared by ultrasonic-assisted forced infiltration (UAFI). When the mass ratio of CNT and Gr reaches 3:1, the thermal conductivity of the CNT-Gr(3:1)/PDMS composite is 4.641 W/(m·K), which is 1619% higher than that of a pure PDMS matrix. In addition, the CNT-Gr(3:1)/PDMS composite also has excellent mechanical properties. The tensile strength and elongation at break of CNT-Gr(3:1)/PDMS composites are 3.29 MPa and 29.40%, respectively. The CNT-Gr/PDMS composite also shows good performance in terms of electromagnetic shielding and thermal stability. The PDMS composites have great potential in the thermal management of electronic devices. [ABSTRACT FROM AUTHOR]

In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The PET surface pre- and post-plasma treatment was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the enhancement mechanism of the interface adhesion was discussed. In addition, the ablation performance of the double-layer tape after the plasma treatment was studied. The results showed that the plasma etching effect increased the root mean square roughness of the PET surface from 1.74 nm to 19.10 nm. In addition, after the plasma treatment, the number of C–OH/COOH bonds and O=C–O bonds increased, which also greatly improved the adhesion between the PET and energetic polymers. In the optimization of the ablation performance, the optimal laser pulse width was about 200 μs. The optimal values of the specific impulse (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) were 390.65 s, 250.82 μN/W, and 48.01%, respectively. The optimization of the adhesion of the double-layer tape and the ablation performance lay the foundation for the engineering application of laser ablation micro-thrusters. [ABSTRACT FROM AUTHOR]

The evaluation of corporation operation efficiency (especially innovation efficiency) has been always a hot topic. The currently popular evaluation methods are data envelopment analysis (DEA) and its improved methods. However, these methods have the following problems: the production process is regarded as a black box, and the actual production relationship between input and output is not analyzed. To solve these problems: (1) the black box theory and production function theory are introduced to uncover the black box of input and output; (2) regression models are used to alleviate the multicollinearity problem of inputs, and the most appropriate model of production relationship is selected; and (3) the results of the production function are compared with the results of the efficiency evaluation from multiple perspectives. Taking rural commercial banks in China as examples to evaluate their innovation efficiency, this article shows the following: (1) with the black box theory and production function theory, the staff, equipment, and intermediate business cost are suitable as innovation input variables, and intermediate business income is suitable as an innovation output variable; (2) the main challenges faced by rural commercial banks are reducing the reliance on human capital investment, strengthening technological innovation, and improving the efficiency of intermediate business cost management, which is hard to reveal with traditional DEA. The method proposed in this article provides an applicable reference for improving DEA method analysis. [ABSTRACT FROM AUTHOR]

An amplitude demodulator with a large dynamic range, based on microelectromechanical systems (MEMS), is proposed in this paper. It is implemented as a cascade of a capacitive and a thermoelectric sensor. Two types of the transducer can improve the measurement range and enhance the overload capacity. This MEMS-based demodulation is realized by utilizing the square law relationship and the low-pass characteristic during the electromechanical and thermoelectric conversion. The fabrication of this device is compatible with the GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that this MEMS demodulator can realize the direct demodulation of an amplitude modulation (AM) signal with a carrier frequency of 0.35–10 GHz, and cover the power range from 0 to 23 dBm. This MEMS demodulator has the advantages of high power handling capability and zero DC power consumption. [ABSTRACT FROM AUTHOR]

For mountain tunnels, ground heat exchangers can be integrated into the tunnel lining to extract geothermal energy for building heating and cooling via a heat pump. In recent decades, many researchers only focused on the thermal performance of tunnel lining Ground Heat Exchangers (GHEs), ignoring the energy efficiency of the heat pump. A numerical model combining the tunnel lining GHEs and heat pump was established to investigate the energy efficiency of the heat pump. The inlet temperature of an absorber pipe was coupled with the cooling load of GHEs in the numerical model, and the numerical results were calibrated using the in situ test data. The energy efficiency ratio (EER) of the heat pump was calculated based on the correlation of the outlet temperature and EER. The heat pump energy efficiencies under different pipe layout types, pipe pitches and pipe lengths were evaluated. The coupling effect of ventilation and groundwater flow on the energy efficiency of heat pump was investigated. The results demonstrate that (i) the absorber pipes arranged along the axial direction of the tunnel have a greater EER than those arranged along the cross direction; (ii) the EER increases exponentially with increasing absorber pipe pitch and length (the influence of the pipe pitch and length on the growth rate of EER fades gradually as wind speed and groundwater flow rate increase); (iii) the influence of groundwater conditions on the energy efficiency of heat pumps is more obvious compared with ventilation conditions. Moreover, abundant groundwater may lead to a negative effect of ventilation on the heat pump energy efficiency. Hence, the coupling effect of ventilation and groundwater flow needs to be considered for the tunnel lining GHEs design. [ABSTRACT FROM AUTHOR]

Fructo-oligosaccharides (FOS) are prebiotics with numerous health benefits. So far, the dissolved oxygen (DO) concentration control strategy for fermentative production of FOS is still unknown. In order to improve FOS production, the effects of DO concentration and fermentation mode on FOS using Aureobasidium pullulans were investigated in this study. The greatest FOS production (123.2 ± 6.2 g/L), with a yield of 61.6% ± 3.0% (g FOS/g sucrose), was obtained in batch culture under high DO concentration. Furthermore, repeated-batch culture revealed that enzyme production and FOS production were not closely associated with cell growth. By keeping the DO concentration above 5% in the repeated-batch culture, a maximum FOS concentration of 548.3 ± 37.4 g/L and yield of 68.6% ± 2.6% (g FOS/g sucrose) were obtained, which were 3.45% and 11.4% times higher than those obtained in the batch culture without DO control, respectively. Additionally, the ratios of 1-fructofuranosyl nystose (GF4) and 1,1,1,1-kestohexose (GF5) were 33.8% and 23.2%, respectively, in the product of repeated-batch culture, but these compounds were not detected in batch culture. Thus, it can be concluded that the DO concentration affects not only the yield of FOS but also the composition of FOS with different degrees of polymerization, which is the key factor in the fermentative production of FOS with a high polymerization degree. [ABSTRACT FROM AUTHOR]

In the paper, poly(ethylene glycol) (PEG) was grafted on the surface of poly(ester-urethane) (SPEU) film with high grafting density for biomedical purposes. The PEG-surface-grafted SPEU (SPEU-PEG) was prepared by a three-step chemical treatment under mild-reaction conditions. Firstly, the SPEU film surface was treated with 1,6-hexanediisocyanate to introduce -NCO groups on the surface with high density (5.28 × 10−7 mol/cm2) by allophanate reaction; subsequently, the -NCO groups attached to SPEU surface were coupled with one of -NH2 groups of tris(2-aminoethyl)amine via condensation reaction to immobilize -NH2 on the surface; finally, PEG with different molecular weight was grafted on the SPEU surface through Michael addition between terminal C = C bond of monoallyloxy PEG and -NH2 group on the film surface. The chemical structure and modified surface were characterized by FT-IR, 1H NMR, X-ray photoelectron spectroscopy (XPS), and water contact angle. The SPEU-PEGs displaying much lower water contact angles (23.9–21.8°) than SPEU (80.5°) indicated that the hydrophilic PEG chains improved the surface hydrophilicity significantly. The SPEU-PEG films possessed outstanding mechanical properties with strain at break of 866–884% and ultimate stress of 35.5–36.4 MPa, which were slightly lower than those of parent film, verifying that the chemical treatments had minimum deterioration on the mechanical properties of the substrate. The bovine serum albumin adsorption and platelet adhesion tests revealed that SPEU-PEGs had improved resistance to protein adsorption (3.02–2.78 μg/cm2) and possessed good resistance to platelet adhesion (781–697 per mm2), indicating good surface hemocompatibility. In addition, due to the high grafting density, the molecular weight of surface-grafted PEG had marginal effect on the surface hydrophilicity and hemocompatibility. [ABSTRACT FROM AUTHOR]