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A new conceptual living-cell-formed ultrahigh performance supercapacitor made from bacteria is proposed, which contains millions of micro-supercapacitors connected in parallel for superior supercapacitive performance.

The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated. For cooperative-competitive network, two different control protocols, fixed-time and fixed-time event-triggered group consensus, are designed. It is demonstrated that there is no Zeno behavior under the designed event-triggered control. Meanwhile, it is proven that for an arbitrary initial state of the system, group consensus within the settling time could be obtained under the proposed control protocols by using matrix analysis and graph theory. Finally, a series of numerical examples are propounded to illustrate the performance of the proposed control protocol.

Cu2ZnSn(S,Se)4 (CZTSSe) thin films were prepared on molybdenum foil substrate by sol–gel method. The effects of selenization temperature on the properties of CZTSSe thin films and CZTSSe/Mo interfaces were studied. The phase structures, elemental compositions, and morphologies of CZTSSe thin films and the morphologies and electrical properties of CZTSSe/Mo interfaces were characterized by X-ray diffraction, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy, and current–voltage (I–V) curve measurement. The experimental results show that CZTSSe phase with trace of secondary phases can be grown on Mo foil substrate. The CZTSSe thin films have enlarged grain size and enhanced crystallinity with the increase of selenization temperature. A thick Mo(S,Se)2 interface layer forms between the CZTSSe thin film and Mo foil substrate. The thickness of Mo(S,Se)2 layer increases with the rise of selenization temperature. When the selenization temperature is 550 °C, the slope of the I–V characteristic curve of CZTSSe/Mo(S,Se)2/Mo structure reaches the maximum. Therefore, the properties of back contact of CZTSSe thin films can be adjusted by selenization temperature.

Oxidative stress of aquatic microorganisms under heavy metal stress is closely reflected by metabolite changes in cells but it is very difficult to study due to the fast metabolism process and severe in-situ measurements hurdle. Herein, the oxidative stress of cadmium on Euglena gracilis was systematically studied through multi-combined techniques. In particular, for the first time electrochemical approach was associated with Raman spectroscopy imaging to vividly to investigate temporal-spatially varied oxidative stress and its effects on cells metabolism, in which former real-time measured a volcanic relation of extracellular hydrogen peroxide versus the increase of cadmium stress, while the latter shows the corresponding metabolic changes by Raman imaging of single cells. This work builds a bridge to unravel the mechanism of cellular oxidative stress under harsh conditions in a more systematic and holistic approach, while holding a great promise to construct heavy metal biosensors precisely monitoring high heavy metal tolerance strains for environmental modification.

Modern steganalysis has been widely investigated, most of which mainly focus on dealing with the problem of detecting whether an inquiry image contains hidden information. However, few articles in the literature study the location of secret bits hidden by modern adaptive steganography. In this paper, we propose a novel algorithm for locating steganographic payload in the spatial domain. We first predict the steganographic scheme and its payload, which is used for generating a random bitstream. Then, the random bits are embedded in the stego image based on the cost matrix in the framework of Syndrome-Trellis Codes (STCs). Next, relying on the differences between two stego images, the extended modification map in couple with the neighboring weight algorithm can be acquired, leading to the location of the hidden bits. Compared with the prior art, the extensive experiments verify that our proposed locating algorithm performs better, in terms of locating accuracy and efficiency.

Poly(3,4-ethylenedioxythiophene) (PEDOT)-based hydrogel has been studied extensively due to its low cost, good chemical/mechanical stability, printability and high biocompatibility, but still suffers from its relatively low conductivity and complex synthesis method. In this work, we use vanadium pentoxide (V

The nanoporous carbon fiber materials derived from electrospun polyacrylonitrile (PAN) fibers doped with zeolitic imidazolate framework are developed here and applied in the microbe fuel cell anode for enhanced interfacial electron transfer. Zeolitic imidazolate fram-8 (ZIF-8) could introduce a large number of mesopores into fibers, which significantly promote indirect electron transfer mediated by flavins (IET). Moreover, it is noted that thinner fibers are more suitable for cytochromes-based direct electron transfer (DET). Furthermore, the enlarged fiber interspace strengthens the amount of biofilm loading but a larger interspace between thick fibers would hinder the formation of continuous biofilm. Consequently, the nanoporous carbon fiber derived from PAN/ZIF-8 composite with a 1:1 wt ratio shows the best performance according to its suitable mesoporous structure and optimal fiber diameter, which delivers a 10-fold higher maximum power density in microbial fuel cells compared to carbon fabric. In this work, we reveal that the proportion of IET and DET in the interfacial electron transfer process varies with different porous structures and fiber diameters, which may provide some insights for designing porous fiber electrodes for microbial fuel cells and also other devices of bioelectrochemical systems.

The intrinsic nano-ZnO and Ni@ZnO were synthesized with Zn(CH3COO)2·2H2O and NaOH by hydrothermal method under the temperature of 120 °C, and the C19H42BrN(CTAB) was used as surface active agent, N...

A novel and simple method was developed to quickly pattern and transfer electrodes with nanostructures for fabricating flexible electronic skin (E-skin). A nano/micro-structure embedded Cu electrode can be fabricated from a solution process-based electroless deposition (ELD) on a frosted plastic substrate and subsequently flipped over with an adhesive tape. The fine nano/microstructures on the Cu layer benefit the pressure-electric response of the pressure sensor, demonstrated a high sensitivity: 2.22 kPa−1. This fabricated flexible E-skin can be used for monitoring human physiological signals, such as wrist pulse and thumb bending. This fabrication method is an economical tool for fast prototyping cost-effective wearable electronics for the detection and prediction of diseases. It offers opportunity for researchers from resource-limited laboratories to work on miniaturized wearable devices.

One-dimensional turbulence (ODT) is an efficient stochastic methodology for turbulent flow simulation with dimensionality reduction. In this study, the conservative compressible ODT model is further developed and applied to address the challenge of accurately and economically modeling high-Reynolds-number wall-bounded compressible turbulent flows. The prohibitively costly direct numerical simulation (DNS) of multiscale motions for fully developed compressible turbulent channel flows is replaced by a much more economical simulation using the conservative compressible ODT model. The quantitative accuracy in capturing the main turbulent features, including the first-order mean statistics and the second-order and third-order turbulent fluctuation statistics, is verified by comparing the ODT results with different canonical DNS results at Mab = 0.5, 1.5, and 3.0. With its accuracy tested, the proposed ODT model is employed to capture the turbulent features of fully developed channel flows at Reynolds numbers widely ranging from 6000 to 60 000. The proposed ODT model reproduces Reynolds number effects in turbulent fluctuation statistics at all three Mach numbers mentioned above. Furthermore, considering the correspondence between the statistical effect of multiscale eddy events stochastically sampled in ODT and the effect of actual multiscale turbulent motions, a mechanism for Reynolds number effects is revealed by analyzing interactions between the multiscale eddy events from the ODT perspective. Evidence shows that the large-eddy motions in the outer region, rather than the small ones in the inner region, contribute to the Reynolds number effects when all these motions are plotted in inner-scaled units.

Direct electron transfer at microbial anodes offers high energy conversion efficiency but relies on low concentrations of redox centers on bacterium membranes resulting in low power density. Here a heat-treatment is used to delicately tune nitrogen-doping for atomic matching with Flavin (a diffusive mediator) reaction sites resulting in strong adsorption and conversion of diffusive mediators to anchored redox centers. This impregnates highly concentrated fixed redox centers in the microbes-loaded biofilm electrode. This atomic matching enables short electron transfer pathways resulting in fast, direct electrochemistry as shown in Shewanella putrefaciens (S. putrefaciens) based microbial fuel cells (MFCs), showing a maximum power output higher than the conventional non-matched nitrogen-doped anode based MFCs by 21 times. This work sheds a light on diffusion mediation for fast direct electrochemistry, while holding promise for efficient and high power MFCs. In microbial fuel cells direct electron transfer offers high energy conversion efficiency, but low concentrations of redox centers on bacterial membranes result in low power density. Here nitrogen-doping is fine tuned to match Flavin reaction sites, converting diffusive mediators to anchored redox centers toward direct electrochemistry.

A global gene expression analysis of Shewanella putrefaciens CN32 cells nearby a nanostructured microbial anode reveals an electrical tension-triggered conversion of anaerobic respiration to aerobic respiration with increased excretion of flavin electron shuttles and cytochrome C proteins, which sheds light on the role of electric tension in cell organisms.

Interfacial electron transfer between an electroactive biofilm and an electrode is a crucial step for microbial fuel cells (MFCs) and other bio-electrochemical systems. Here, a hierarchically porous nitrogen-doped carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composite with polyaniline as the nitrogen source has been developed for the MFC anode. This composite possesses a nitrogen atom-doped surface for improved flavin redox reaction and a three-dimensional hierarchically porous structure for rich bacterial biofilm growth. The maximum power density achieved with the N-CNTs/rGO anode in S. putrefaciens CN32 MFCs is 1137 mW m–2, which is 8.9 times compared with that of the carbon cloth anode and also higher than those of N-CNTs (731.17 mW m–2), N-rGO (442.26 mW m–2), and the CNTs/rGO (779.9 mW m–2) composite without nitrogen doping. The greatly improved bio-electrocatalysis could be attributed to the enhanced adsorption of flavins on the N-doped surface and the high density of biofilm adhesion for fa...

In this work, cohesive thermoplastic-assisted patterning was successfully used to fabricate versatile 2D and 3D electrodes for biosensing application. The cohesive thermoplastic template was fabricated by cutter shaping to remove wet-chemical processes and UV-lithography. This low cost approach is compatible with versatile inks and substrates. Both single and multi-step grafting of inks work well with cohesive thermoplastic templates to form electronic units on substrates. Other than work on a 2D flat substrate, the cohesive thermoplastic origami can easily fabricate electrodes on 3D objects, demonstrating itself as a good candidate to implant electronic unit on a stereotype object. The flexibility, convenience and operability seen here make this method a fast prototype method to evaluate the proof-of-concept design. It also provides alternative fabrication solutions for researchers from resource-limited laboratories to work on miniaturized devices.

A three dimensional (3D) porous nickel oxide (NiO)/graphene composite is developed through one-pot hydrothermal synthesis with a biopolymer-pectin for tailoring the porous structure. The introduction of pectin makes the NiO grow into nanoflakes-assembled micro spheres that insert in the graphene layers rather than just deposit on the surface of graphene nanosheets as nanoparticles. As the increase of pectin ratio, the size and the amount of NiO micro spheres are both increased, which resulting a 3D hierarchical porous structure. With the optimized pectin concentration, the obtained NiO/graphene nanocomposite anode possesses good electrocatalytic capability and delivers maximum power density of 3.632 Wm−2 in Shewanella putrefaciens CN32 microbial fuel cells (MFCs). This work provides a new way to develop low cost, high performance anode materials for MFCs.

Mesoporous carbon (MC) is supposed to be a good candidate for microbial fuel cell (MFC) anodes as it possesses a large specific area for the redox reaction of the electron shuttles and should deliver high power density. However, the power generation performance of MC anodes is often un-satisfying. It seems that a large portion of the pore surface is not available for anodic redox reaction but the reason is not clear. Here, three MCs with different pore sizes and pore shapes were fabricated and used to explore the effect of the pore structure on the bioelectrocatalysis in Shewanella putrefaciens CN32 MFCs. It is interesting that MC with 40–60 nm spheric pores (MC-III) possesses superior bio-electrocatalytic performance to the CMK-3 (MC-I with 3 nm channel like pores) and the one with 14 nm spheric pores (MC-II) although the specific surface area of MC-III is lower than MC-II and MC-I. The reason might be that the MC-III provides a more favorable pore structure than the other two MCs for flavin based redox reaction at the interface between the biofilm and the electrode. As a result, the MC-III anode delivered the highest power density at around 1700 mW m−2, which is 1.6 fold higher than that of the MC-I anode. A possible mechanism for the pore shape/size dependent interfacial electron transfer process has also been proposed. This work reveals that spheric mesopores with large pore width could be more favorable than the narrow channel-like pores for flavin based interfacial electron transfer in biofilm anodes, which will provide some insights for the design of the mesoporous anode in MFCs.

The microbial fuel cell (MFC) is an attractive green energy source since it can use wastewater and/or organic wastes as fuels to generate electricity. A cost-effective anode material with superior bioelectrocatalysis activity is critical to MFC. In this study, a honeycomb-like hierarchical porous carbon–silica (PC/Si) composite with macropores (2–15 μm) and mesopores (3–4 nm) was derived from distiller's grains via a simple carbonization procedure and used as an anode in a Shewanella putrefaciens CN32 (S. putrefaciens CN32) fuel cell for the first time. The obtained three dimensional scaffold structure with meso pores on the wall provides not only a large surface for bacteria adhesion, but also more active sites for flavin mediated interfacial electron transfer. It is interesting that the siliceous crusts of this PC/Si composite greatly promote the bacteria adhesion as well as a uniform biofilm formation. Accordingly, the PC/Si anode delivers a maximum power density of 580.7 mW m−2 in S. putrefaciens CN32 MFC, which is 4.5-fold higher than that of the conventional carbon cloth anode. Considering the synthesis process of this biomass based carbon material is facile, this PC/Si anode could be very promising when applied for high performance, large scale MFC.

Reversible data hiding ensures that the legitimate recipient can completely recover the original image and additional data. However, in order to hide the original image content, the content-owner might encrypt the image locally first. Thus reversible data hiding in encrypted images (RDHEI) has attracted wide attention, which can be used for cloud storage and privacy protection. In this paper, a high-capacity and secure RDHEI method based on adaptive prediction-error labeling (APL) is proposed, which takes advantage of the Laplacian-like distribution of prediction errors. To increase the reserved room before encryption, we present two approaches that combine APL and encryption. One pessimistically exposes the shuffled labels in encrypted images, while the other optimistically performs the encryption on the labels. Dependent of both approaches, the original image and additional data can be completely and separately recovered if the recipient has the secret key. More importantly, security of RDHEI is emphasized, not only the invisibility of image content, but also the undetectability of additional data. Experimental results show that our method is able to achieve higher embedding capacity and relevant security compared with prior arts.

An in-situ deposition of a spider net-like NiO nanowires onto a nitrogen-doped carbon nanowire forming a macroporous network on carbon cloth (NiO@N-CNWs/CC) is a new facile approach to fabricate a substrate on which Shewanella Putrefaciens grows. The NiO@N-CNWs/CC associated with biofilm is a multi-layers of bacterium cells on a conductive current collector, which significantly boosts the power density higher than that of carbon cloth by 8.5 times, even though it is typically very difficult to grow a thick biofilm with high biocatalyst to raise the relatively low power density usually found in microbial fuel cells (MFCs). The NiO nanowires play a bifunctional role in promoting the high power density of NiO@N-CNWs/CC MFCs: 1) such a macroporous surface anchors the first layer of bacterium cells tightly, and allows more layers of cells growing on its top for a thick film, 2) the very conductive NiO nanowires network enables the fast electron transfer/transport through the thick biofilm for achieving the high power density.

Dopamine (DA) as an important neurotransmitter plays an important role in physiological activities, and its abnormal level can cause diseases such as Parkinson's disease. However, the clinical analysis of DA mainly relies on time-consuming and expensive liquid chromatography and molecular spectrometer. We present here a design and fabrication of inexpensive strip sensor constructed from screen printed electrodes for sensitive and selective detection of DA. The ink used for printing the strips contains Shewanella putrefaciens-templated porous N-doped carbon nanorods (N-doped CN) and Au nanoparticles (Au NPs), in which the N-doping enhances CN's negative charge to electrostatically attract the positively charged DA with strong adsorption for achieving fast electron transfer. Moreover, results indicate that the Au NPs impregnation in N-doped CN renders much more catalytic reaction sites toward DA oxidation current. The strip sensor exhibits high sensitivity for DA detection with a broad linear range of 0.02–700 μM and a low detection limit of 0.007 μM as well as good selectivity and superior flexibility for great potential in wearable applications. The strip sensor further performs an accurate detection of DA in human serum, providing a powerful analytical tool for diagnosis of DA related diseases in clinical analysis.

Lithium-selenium (Li-Se) batteries are of great interest as a representative family of electrochemical energy storage systems because of their high theoretical volumetric capacity and considerable electronic conductivity. However, the main drawback of Se electrodes is the rapid capacity fading caused by the dissolution of polyselenides upon cycling. Here, we report a simple, economical, and effective method for the synthesis of three-dimensional (3D) hierarchical porous carbon with a hollow tubular structure as a host matrix for loading Se and trapping polyselenides. The as-obtained porous tubular carbon shows a superior specific surface area of 1786 m2 g−1, a high pore volume of 0.79 cm3 g−1, and many nanostructured pores. Benefiting from the unique structural characteristics, the resulting hierarchical porous carbon/Se composite exhibits a high capacity of 515 mAh g−1 at 0.2 C. More importantly, a remarkable cycling stability over 900 cycles at 2 C with a capacity fading rate of merely 0.02% per cycle can be achieved. The 3D hollow porous tubular carbon can be also used for other high-performance electrodes of electrochemical energy storage.

Oral drug delivery has been considered as a promising strategy for ulcerative colitis (UC) therapy. Here, an emulsion solvent evaporation technique was employed to prepare non-porous curcumin (CUR)-loaded polymeric nanoparticles (NPs) and porous CUR-loaded polymeric NPs in the absence or presence of ammonium bicarbonate. The resultant CUR-loaded NPs (non-porous NPs and porous NPs) had a desirable mean particle size of around 260 nm with a narrow size distribution, a uniform pore size distribution, slightly negatively-charged surface, high encapsulation efficiency and controlled drug release capacity. In vitro experiments indicated that Raw 264.7 macrophages exhibited time-dependent accumulation profiles of NPs during the initial 2 h of co-incubation. Furthermore, we found that porous NPs inhibited the secretion of the main pro-inflammatory cytokines (TNF-α, IL-6 and IL-12) and the production of reactive oxygen species much more efficiently than non-porous NPs. Most importantly, in vivo studies demonstrated that oral administered porous NPs had superior therapeutic efficiency in alleviating UC compared with non-porous NPs. The results collectively suggest that porous polymeric NPs can be exploited as efficient oral drug carriers for UC treatment.

Exploration of sustainable electrocatalysts toward oxygen reduction reaction (ORR) with high catalytic activity remains a key challenge in the development of metal–air batteries and fuel cells. In this work, a hybrid electrocatalyst composed of cobalt (Co/CoOx) nanoparticles encapsulated in Co/N-doped mesoporous graphene (Co/CoOx@Co/N-graphene) is reported for efficient ORR catalysis. The catalyst is rationally designed and synthesized via a facile combination of spontaneous one-pot polymerization of dopamine in the presence of graphene oxide (GO) and Co2+ ions and the subsequent carbonization process. The morphology, doping nature and ORR activity of the as-prepared catalyst are systematically investigated. It is found that there are abundant Co/N active sites and Co/CoOx nanoparticles in this hybrid catalyst, leading to a synergistic enhancement effect for improved ORR activity. In an alkaline environment, this Co/CoOx@Co/N-graphene catalyst displays Pt/C-comparable ORR activity in terms of half-wave potential and four-electron reduction selectivity, and higher limiting current density, better methanol tolerant ability and long-term durability. When being evaluated in a Zn–air battery, it demonstrates superior performance to the commercial Pt/C catalyst.

Lead contamination in soil has become a worldwide threat on food security and human health. To assess the Pb bioavailability and evaluate the safe use of low Pb polluted soil for food production, the speciation of Pb in 19 types of paddy soil were investigated by chemical extraction and X-ray absorption near-edge structure (XANES), and the uptake and accumulation characteristics of Pb in different soil-rice systems were investigated. Moreover, an empirical model was established to predict the content of Pb in rice grain, and field validation was conduct to evaluate model performance. Results showed that the proportion of available Pb in different soil satisfied normal distribution N (0.47, 0.23). Pb(CH3COO)2, GSH-Pb, PbO, PbHPO4 and Pb3(PO4)2 performed well in characterizing the speciation of Pb in different rhizosphere soils, and PbHPO4 accounted for more than 70%. The exceedance of Pb in grain in CK, 0.5X and 1X treatment were 10.5%, 36.1% and 42.1%, respectively, and the accumulation of Pb in grain was significantly related with Pb content in root. Carbonate and organic bound Pb in rhizosphere soil were two major Pb species that influenced the accumulation of Pb in rice. Moreover, content of total Pb, clay and SOM performed well in predicting the Pb content in grain, both for pot and field samples. Above all, our predicting model worked well in evaluating Pb accumulation in rice grain among low polluted paddy farmland (Total Pb

Lead (Pb) contaminated in farmlands has become a deep threat to global food security and human health. In this study, the bioavailability of Pb in 18 types of soil to wheat (Triticum aestivum L.) grains were investigated, and reliable empirical models of Pb in wheat grains were established based on soil properties. The results showed that the average bioconcentration factor (BCFgrain/total-Pb) in acidic soils was approximately 3.30 times than that in alkaline soils (ANOVA P