A sensitive electrochemical sensor based on polypyrrole/electrochemically reduced graphene oxide for the determination of imidacloprid

The glassy carbon electrode (GCE) was modified by electrochemically reduced graphene oxide (ERGO) and polypyrrole (PPy) prepared by simple cyclic voltammetry (CV) electropoly­merization. The PPy/ERGO modified electrode (PPy/ERGO/GCE) was used as a platform of electrochemical sensor to detect imidacloprid (IMI) insecticide. CV and differential pulse voltammetry (DPV) were chosen as the methods to investigate of the electrochemical behavior of IMI on PPy/ERGO/GCE surface. Scanning electron microscopy (SEM) and Raman spectra were utilized to describe the morphology and structure of the modified electrode. Experimental parameters were optimized, such as the number of polymerization cycles, scan rate and the pH value of electrolyte. Under the optimized conditions, when the concentration of IMI was in the range of 1-10 μM and 10-60 μM, the increase of reduction peak current was linear with the concentration of IMI, and the low detection limit was found to be 0.18 μM (S/N = 3). Results showed that PPy/ERGO/GCE demonstrated satisfactory reproducibility and stability, and has great potential in actual sample testing

A targetable acid-responsive micellar system for signal activation based high performance surgical resolution of tumors

973 program [2013CB93390]; NSF China [21272196, 21072162, 30830092, 30921005, 91029304, 81061160512]; PCSIRT; Fundamental Research Funds for the Central Universities [2011121020]Tumor-reporting probes are valuable to guide surgical resection of tumor foci elusive to visual inspection. As tumors display distinct arrays of lectins, we herein report the construction and screening of a panel of glycan-displaying smart micelles for tumor illumination in mice. These micelles consist of cores of rhodamine-sultam (RST) responsive to lysosomal acidity and a corona of poly[styrene-alter-(maleic acid)] glycosylated with D-glucosamine, D-mannosamine or D-galactosamine. These nanoscale micelles are nonfluorescent extracellularly and become luminescent within acidic lysosomes, enabling optical tracking of tumor endocytosis of the micelles. In vivo screening revealed high-efficiency uptake and fluorescence activation of galactosylated micelles (RST@P-Gal) by subcutaneous tumor and disseminated liver tumor foci with diameters of 0.1-10 mm, which is significantly below minimal residual cancer (a minimum of 1 cm clearance). This system is readily adapted to illuminate different tumors by expanding the diversity of glycans on the shell. Given the robustness and high performance of this system, lectin-targeted responsive micelles are attractive for diagnosis or surgical ablation of tumors

A fluorescently labelled sialic acid for high performance intraoperative tumor detection

973 program [2013CB93390]; NSF China [21272196, 30830092, 30921005, 91029304, 81061160512]; PCSIRT; Fundamental Research Funds for the Central Universities [2011121020]Surgical resection is widely used for tumor treatment, necessitating approaches for the precise locating of elusive tumor foci. We report the high performance detection of tumors in mice with fluorescein-isothiocyanate (FITC) labelled sialic acid (FITC-SA), a fluorescent monosaccharide with low cytoxicity. Analysis of mice intravenously injected with FITC-SA revealed high target-to-background fluorescence ratios in subcutaneous tumors and liver tumor implants with 0.2-5 mm diameters, which are significantly below the clinical threshold of minimal residual cancer (similar to 1 cm clearance). Extracellular FITC-SA is quickly cleared from circulation whereas the intracellular FITC-SA could be metabolically incorporated into glycoproteins via a cellular sialylation pathway. Compared with FITC-SA-laden nanoparticles, free FITC-SA is preferentially and quickly taken up by tumors in mice and displays high tumor-to-background signal contrast, suggesting the potential for fluorescence directed surgical ablation of tumors

Haem oxygenase delays programmed cell death in wheat aleurone layers by modulation of hydrogen peroxide metabolism

Haem oxygenase-1 (HO-1) confers protection against a variety of oxidant-induced cell and tissue injury in animals and plants. In this report, it is confirmed that programmed cell death (PCD) in wheat aleurone layers is stimulated by GA and prevented by ABA. Meanwhile, HO activity and HO-1 protein expression exhibited lower levels in GA-treated layers, whereas the hydrogen peroxide (H2O2) content was apparently increased. The pharmacology approach illustrated that scavenging or accumulating H2O2 either delayed or accelerated GA-induced PCD. Furthermore, pretreatment with the HO-1 specific inhibitor, zinc protoporphyrin IX (ZnPPIX), before exposure to GA, not only decreased HO activity but also accelerated GA-induced PCD significantly. The application of the HO-1 inducer, haematin, and the enzymatic reaction product of HO, carbon monoxide (CO) aqueous solution, both of which brought about a noticeable induction of HO expression, substantially prevented GA-induced PCD. These effects were reversed when ZnPPIX was added, suggesting that HO in vivo played a role in delaying PCD. Meanwhile, catalase (CAT) and ascorbate peroxidase (APX) activities or transcripts were enhanced by haematin, CO, or bilirubin (BR), the catalytic by-product of HO. This enhancement resulted in a decrease in H2O2 production and a delay in PCD. In addition, the antioxidants butylated hydroxytoluene (BHT), dithiothreitol (DTT), and ascorbic acid (AsA) were able not only to delay PCD but also to mimic the effects of haematin and CO on HO up-regulation. Overall, the above results suggested that up-regulation of HO expression delays PCD through the down-regulation of H2O2 production

Analysis of Natural Ventilation Performance Gap between Design Stage and Actual Operation of Office Buildings

Suitable natural ventilation in office buildings can not only reduce energy consumption of air conditioning, but also improve indoor air quality. In the architectural design stage, the effect of natural ventilation design is mainly simulated by CFD simulation software for indoor air speed, pressure, and age of air, etc.. However, during the actual building operation, the indoor natural ventilation effect will be affected by many factors, such as surrounding buildings, indoor layout, window position and open-close status, human behavior, etc., and the natural ventilation performance between design stage and actual operation is often different. In this paper, a typical office building was selected and FloVENT software was used to quantitatively analyse the influence of surrounding buildings, indoor layout, door/window opening conditions on indoor natural ventilation. Field measurement of indoor air flow rates in typical positions in office were carried out under different circumstances. In order to reduce the instantiate influence of outdoor wind speeds, a new index named Wind Speed Ratio(WSR) is put forward.Through comparative analysis of simulated data and measured data. the gap degree in natural ventilation performance between design stage and operation operation is discussed, and results show that the relative errors of the WSR, which could be considered to reflect the performance gap, are about 78.0%, 28.7% and 150% respectively, under corresponding condition settings of surrounding buildings, indoor layout, and door/window opening

Research on Retinex Algorithm Combining with Attention Mechanism for Image Enhancement

Considering the high noise and chromatic aberration in the Retinex-Net image enhancement results, this paper put forward a modified Retinex-Net algorithm for weak illumination image enhancement based on the Decom-Net and Enhance-Net structures of Retinex-Net. The improved structure proposed in this paper adds the attention mechanism ECA-Net into the Decom-Net and Enhance-Net convolution layer of the original Retinex-Net structure, which can effectively reduce the problem of irrelevant background and local brightness imbalance, activate sensitive features, and improve the image’s details and brightness processing ability. Additionally, deep connected attention networks are embedded between the introduced attention modules, so that all of the attention modules can be trained jointly to improve the learning ability. Furthermore, the improved method also introduces a noise reduction loss function and a color loss function to suppress noise and to reduce image color distortion. The test results of the proposed method indicate that the image’s overall brightness can be balanced, the local areas cannot be overexposed, and more image details and color information can be retained than with other enhancement algorithms

A P2P Query Algorithm for Opportunistic Networks Utilizing betweenness Centrality Forwarding

With the proliferation of high-end mobile devices that feature wireless interfaces, many promising applications are enabled in opportunistic networks. In contrary to traditional networks, opportunistic networks utilize the mobility of nodes to relay messages in a store-carry-forward paradigm. Thus, the relay process in opportunistic networks faces several practical challenges in terms of delay and delivery rate. In this paper, we propose a novel P2P Query algorithm, namely Betweenness Centrality Forwarding (PQBCF), for opportunistic networking. PQBCF adopts a forwarding metric called Betweenness Centrality (BC), which is borrowed from social network, to quantify the active degree of nodes in the networks. In PQBCF, nodes with a higher BC are preferable to serve as relays, leading to higher query success rate and lower query delay. A comparison with the state-of-the-art algorithms reveals that PQBCF can provide better performance on both the query success Ratio and query delay, and approaches the performance of Epidemic Routing (ER) with much less resource consumption