Rapid and Non-Destructive Detection of Decay in Peach Fruit at the Cold Environment Using a Self-Developed Handheld Electronic-Nose System

Non-destructive detection of decay in fruit in real time during cold chain is important to recycle the decayed fruit in time for reverse supply chain. Fruit is commonly stored inside external packages during cold chain, making neither manual observation nor optical inspection techniques available to detect the decay in fruit. In this work, the potential of a self-developed handheld electronic nose (e-nose) instrument to non-destructively acquire volatile substances and then detect decay in peach fruit during cold chain (0 °C) was explored. A desktop e-nose instrument was considered as a comparison. The storage days of peach fruit during storage were also predicted by two instruments. Partial least squares discriminant analysis and least squares support vector machines (LS-SVM) were used for the classification of decay in peach fruit. Partial least squares regression and LS-SVM were used for the prediction of the storage days. Successive projection algorithm (SPA), uninformation variable elimination (UVE), UVE-SPA, and competitive adaptive reweighted sampling were applied to select the characteristic variables from e-nose data. The best model for the classification of decayed fruit during cold chain by the handheld e-nose instrument had the correct answer rate of prediction of 95.83% (94.64% for healthy samples and 100.00% for decayed samples). The best model for predicting the storage days of peach fruit during cold chain by the handheld e-nose instrument had the residual predictive deviation value of 9.283. The results indicate that the self-developed handheld e-nose system is a simple and non-destructive tool to detect decay in peach fruit during cold storage.     

Fine‐Tuning Intrinsic Strain in Penta‐Twinned Pt–Cu–Mn Nanoframes Boosts Oxygen Reduction Catalysis

Tuning the intrinsic strain of Pt‐based nanomaterials has shown great promise for improving the oxygen reduction reaction (ORR) performance. Herein, reported is a tunable surface strain in penta‐twinned ternary Pt–Cu–Mn nanoframes (NFs). Pt–Cu–Mn ultrafine NFs (UNFs) exhibit ≈1.5% compressive strain compared to Pt–Cu–Mn pentagonal NFs (PNFs) and show the superior activity toward ORR in an alkaline environment. Specifically, the specific and mass activity of Pt–Cu–Mn UNFs are 3.38 mA cm^?2 and 1.45 A mg^?1, respectively, which is 1.45 and 1.71 times higher than that of Pt–Cu–Mn PNFs, demonstrating that compressive strain in NFs structure can effectively enhance the catalytic activity of ORR. Impressively, Pt–Cu–Mn UNFs exhibit 8.67 and 9.67 times enhanced specific and mass activity compared with commercial Pt/C. Theoretical calculations reveal that compression on the surface of Pt–Cu–Mn UNFs can weaken the bonding strengths and adsorption of oxygen‐containing intermediates, resulting in an optimal condition for ORR.     

Photosynthetic Biohybrid Nanoswimmers System to Alleviate Tumor Hypoxia for FL/PA/MR Imaging‐Guided Enhanced Radio‐Photodynamic Synergetic Therapy

Biohybrid microswimmers have recently shown to be able to actively perform in targeted delivery and in vitro biomedical applications. However, more envisioned functionalities of the microswimmers aimed at in vivo treatments are still challenging. A photosynthetic biohybrid nanoswimmers system (PBNs), magnetic engineered bacteria‐Spirulina platensis, is utilized for tumor‐targeted imaging and therapy. The engineered PBNs is fabricated by superparamagnetic magnetite (Fe₃O₄ NPs) via a dip‐coating process, enabling its tumor targeting ability and magnetic resonance imaging property after intravenous injection. It is found that the PBNs can be used as oxygenerator for in situ O₂ generations in hypoxic solid tumors through photosynthesis, modulating the tumor microenvironment (TME), thus improving the effectiveness of radiotherapy (RT). Furthermore, the innate chlorophyll released from the RT‐treated PBNs, as a photosensitizer, can produce cytotoxic reactive oxygen species under laser irradiation to achieve photodynamic therapy. Excellent tumor inhibition can be realized by the combined multimodal therapies. The PBNs also possesses capacities of chlorophyll‐based fluorescence and photoacoustic imaging, which can monitor the tumor therapy and tumor TME environment. These intriguing properties of the PBNs provide a promising microrobotic platform for TME hypoxic modulation and cancer theranostic applications.     

Synchronization of Switched Neural Networks with Time‐varying Delays via Sampled‐data Control

This paper investigates sampled‐data synchronization control of switched neural networks with time‐varying delays under average dwell time. Based on the delay system method, the sampled‐data synchronization system is proposed with time‐varying delays and input delays in the unified framework for switched neural networks. By constructing a suitable Lyapunov‐Krasovskii functional and free‐weighting matrix, the relationship between the average dwell time and the maximum sampling interval is revealed to form delay‐dependent exponentially synchronization criteria. The desired mode‐dependent controller under the maximum sampling interval and decay rate is designed. Finally, two numerical examples are provided to demonstrate the effectiveness and feasibility of the proposed techniques.     

考虑质量与安全因素的挣值管理及其应用

针对传统挣值管理(Earned Value Management,EVM)模型中未纳入反映质量和安全等不确定性因素的量化指标,难以衡量质量和安全对项目成本、进度的影响,以至于很难有效适用于工程实际应用的问题,将工程项目管理所关注的质量和安全要素加入EVM的监测范围,在传统EVM的前提下,对安全指标进行量化评价,同时引入用于评定质量的质量指数,建立改进EVM模型。将改进的安全-质量挣值模型作为评价指标,分析考虑质量、安全要素后的进度或成本运行情况,并作为判断进度或成本变化是否受该不确定性因素影响的依据。最后将其应用于实际工程中,验证了该改进EVM在工程实践中的可行性。     

Facile synthesis of Ni-, Co-, Cu-metal organic frameworks electrocatalyst boosting for hydrogen evolution reaction

The conductive metal-organic frameworks (MOFs) are suggested as the ideal electrocatalysts for hydrogen evolution reaction (HER) because of the high utilization of metal atoms.Rational design and facile synthesis of MOFs with large specific surface area,proper metals as center,and tunable chemical components is still full of challenges.Herein,we report the facile synthesis three types of porous MOFs by regulating metal center using benzene-1,3,5-tricarboxylic acid (H3BTC) as organic ligand and have successfully synthesized the rhombic octahedral Cu-BTC,rod-shaped Co-BTC and spherical Ni-BTC materials with large specific surface area ranged in 350-500 m2 g-1.These as-prepared MOFs materials exhibit high performance of HER in 0.5 M H2SO4.Ni-BTC material exhibits the lowest overpotential of 53 mV at 10 mA cm-2 and the smallest Tafel slope of 62 mV dec-1 than those of Cu-BTC (270 mV,155 mV dec-1) and Co-BTC (123 mV,100 mV dec-1),which are much superior to these previously reported MOFs catalysts.In addition,the fast catalytic kinetic of Ni-BTC was confirmed by the smaller charge transfer resistance (Rct)value of 0.9 Ω and larger electrochemical active surface area (ECSA) of 35.5 cm2 than those of Cu-BTC (8.2 Ω,22.5 cm2) and Co-BTC (1.9 Ω,27.7 cm2).Because of the structural advantage and large ECSA,the turnover frequency (TOF) value of Ni-BTC reaches up to 0.041 s-1 at 120 mV overpotential,which is 20.5 and 2.6 times greater than that of Cu-BTC (0.002 s-1) and Co-BTC (0.016 s-1).Besides,these three types of MOFs exhibited excellent durability over 12 h.This study unfolds diverse insights into the design and facile synthesis of MOFs for electrochemical energy conversion system.