Investigation on the RONS and Bactericidal Effects Induced by He + O2 Cold Plasma Jets: In Open Air and in an Airtight Chamber

He + O2 plasma jets in open air and in an airtight chamber are comparatively studied, with respect to their production of gaseous/aqueous reactive species and their antibacterial effects. Under the same discharge power, the plasma jet in open air has higher densities of gaseous reactive species and a higher concentration of aqueous H2O2 but lower concentrations of aqueous OH and O2-. In addition, the increase in the O2 ratio in He in both plasma jets causes a linear decrease in the population of gaseous reactive species, except for O(3p5P) when a small amount of O2 is added to the working gas. The concentrations of aqueous reactive species for OH and H2O2 also drop monotonically with the increase in additive O2, while the aqueous O2- first increases and then decreases. Moreover, it is interesting that the bactericidal inactivation in the airtight chamber condition is much greater than that in the open air condition regardless of the presence or absence of additive O2 in the He plasma jet. The concentration trends of O2- for both the plasma jets are similar to their antibacterial effects, and little antibacterial effect is achieved when a scavenger of O2- is used, indicating that O2- should be a main antibacterial agent. Moreover, it should not be O2- alone to achieve the antibacterial effect, and some reactive nitrogen species such as ONOO- and O2NOO- might also play an important role

Effects of biochar and arbuscular mycorrhizal fungi on winter wheat growth and soil N2O emissions in different phosphorus environments

IntroductionPromoting crop growth and regulating denitrification process are two main ways to reduce soil N2O emissions in agricultural systems. However, how biochar and arbuscular mycorrhizal fungi (AMF) can regulate crop growth and denitrification in soils with different phosphorus (P) supplies to influence N2O emission remains largely unknown.MethodHere, an eight-week greenhouse and one-year field experiments biochar and/or AMF (only in greenhouse experiment) additions under low and high P environments were conducted to characterize the effects on wheat (Triticum aestivum L.) growth and N2O emission.ResultsWith low P supply, AMF addition decreased leaf Mn concentration (indicates carboxylate-releasing P-acquisition strategies), whereas biochar addition increased leaf Mn concentration, suggesting biochar and AMF addition regulated root morphological and physiological traits to capture P. Compared with low P supply, the high P significantly promoted wheat growth (by 16-34%), nutrient content (by 33-218%) and yield (by 33-41%), but suppressed soil N2O emissions (by 32-95%). Biochar and/or AMF addition exhibited either no or negative effects on wheat biomass and nutrient content in greenhouse, and biochar addition promoted wheat yield only under high P environment in field. However, biochar and/or AMF addition decreased soil N2O emissions by 24-93% and 32% in greenhouse and field experiments, respectively. This decrease was associated mainly with the diminished abundance of N2O-producing denitrifiers (nirK and nirS types, by 17-59%, respectively) and the increased abundance of N2O-consuming denitrifiers (nosZ type, by 35-65%), and also with the increased wheat nutrient content, yield and leaf Mn concentration.DiscussionThese findings suggest that strengthening the plant-soil-microbe interactions can mitigate soil N2O emissions via manipulating plant nutrient acquisition and soil denitrification

Comparison Between the Water Activation Effects by Pulsed and Sinusoidal Helium Plasma Jets

Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2−, and O2−/ONOO− induced by the pulsed plasma jet have higher concentrations, and the proportional difference increases with the discharge power. However, the emission intensities of OH(A) and O(3p5P) are higher for the sinusoidal plasma jet, which may be attributed to its higher gas temperature since more water vapor could participate in the plasma. In addition, the efficiency of bacterial inactivation induced by the pulsed plasma jet is higher than that for the sinusoidal plasma jet, in accordance with the concentration relation of aqueous reactive species for the two types of plasma jets. Published by AIP Publishing

Enhanced electrochemical performance of CuCo2S4/carbon nanotubes composite as electrode material for supercapacitors

CuCo2S4 is regarded as a promising electrode material for supercapacitor, but has inferior conductivity and poor cycle stability which restrict its wide-range applications. In this work, hierarchically hybrid composite of CuCo2S4/carbon nanotubes (CNTs) was synthesized using a facile hydrothermal and sulfuration process. The embedded CNTs in the CuCo2S4 matrix provided numerous effective paths for electron transfer and ion diffusion, and thus promoted the faradaic reactions of the CuCo2S4 electrode in the energy storage processes. The CuCo2S4/CNTs-3.2% electrode exhibited a significantly increased specific capacitance of 557.5 F g-1 compared with those of the pristine CuCo2S4 electrode (373.4 F g-1) and CuO/Co3O4/CNTs-3.2% electrode (356.5 F g-1) at a current density of 1 A g-1. An asymmetric supercapacitor (ASC) was assembled using the CuCo2S4/CNTs-3.2% as the positive electrode and the active carbon as the negative electrode, which exhibited an energy density of 23.2 Wh kg-1 at a power density of 402.7 W kg-1. Moreover, the residual specific capacitance of this ASC device retained 85.7 % of its original value after tested for 10000 cycles, indicating its excellent cycle stability

ChainSplitter: Towards Blockchain-based Industrial IoT Architecture for Supporting Hierarchical Storage

The fast developing Industrial Internet of Things (IIoT) technologies provide a promising opportunity to build large-scale systems to connect numerous heterogeneous devices into the Internet. Most existing IIoT infrastructures are based on a centralized architecture, which is easier for management but cannot effectively support immutable and verifiable services among multiple parties. Blockchain technology provides many desired features for large-scale IIoT infrastructures, such as decentralization, trustworthiness, trackability, and immutability. This paper presents a blockchain-based IIoT architecture to support immutable and verifiable services. However, when applying blockchain technology to the IIoT infrastructure, the required storage space posts a grant challenge to resource-constrained IIoT infrastructures. To address the storage issue, this paper proposes a hierarchical blockchain storage structure, \textit{ChainSplitter}. Specially, the proposed architecture features a hierarchical storage structure where the majority of the blockchain is stored in the clouds, while the most recent blocks are stored in the overlay network of the individual IIoT networks. The proposed architecture seamlessly binds local IIoT networks, the blockchain overlay network, and the cloud infrastructure together through two connectors, the \textit{blockchain connector} and the \textit{cloud connector}, to construct the hierarchical blockchain storage. The blockchain connector in the overlay network builds blocks in blockchain from data generated in IIoT networks, and the cloud connector resolves the blockchain synchronization issues between the overlay network and the clouds. We also provide a case study to show the efficiency of the proposed hierarchical blockchain storage in a practical Industrial IoT case

SMChain: A Scalable Blockchain Protocol for Secure Metering Systems in Distributed Industrial Plants

Metering is a critical process in large-scale distributed industrial plants, which enables multiple plants to collaborate to offer mutual services without outside interference. When distributed plants measure the data from a shared common source, e.g., flow metering in an oil pipeline, trustworthiness and immutability must be guaranteed among them. In this paper, we propose a hierarchical and scalable blockchain-based secure metering system, \textit{SMChain}, to provide strong security, trustworthy guarantee, and immutable services. {\em SMChain} adopts a two-layer blockchain structure, consisting of independent local blockchains stored at individual plants and one state blockchain stored in the cloud. To deal with the scalability issues within each plant, we propose a novel scalable Byzantine Fault Tolerance (BFT) consensus protocol based on \textit{(k, n)}-threshold signature scheme to deal with the Byzantine faults and reduce the intra-plant communication complexity from $O(n^2)$ to $O(n)$. For the state blockchain, we use a cloud-based service to synchronize and integrate the local blockchains into one state blockchain, which can further be distributed back to each plant

SoK: Sharding on Blockchain

Blockchain is a distributed and decentralized ledger for recording transactions. It is maintained and shared among the participating nodes by utilizing cryptographic primitives. A consensus protocol ensures that all nodes agree on a unique order in which records are appended. However, current blockchain solutions are facing scalability issues. Many methods, such as Off-chain and Directed Acyclic Graph (DAG) solutions, have been proposed to address the issue. However, they have inherent drawbacks, e.g., forming parasite chains. Performance, such as throughput and latency, is also important to a blockchain system. Sharding has emerged as a good candidate that can overcome both the scalability and performance problems in blockchain. To date, there is no systematic work that analyzes the sharding protocols. To bridge this gap, this paper provides a systematic and comprehensive review on blockchain sharding techniques. We first present a general design flow of sharding protocols and then discuss key design challenges. For each challenge, we analyze and compare the techniques in state-of-the-art solutions. Finally, we discuss several potential research directions in blockchain sharding

Effects of detection-beam focal offset on displacement detection in optical tweezers

A high-resolution displacement detection can be achieved by analyzing the scattered light of the trapping beams from the particle in optical tweezers. In some applications where trapping and displacement detection need to be separated, a detection beam can be introduced for independent displacement detection. However, the detection beam focus possibly deviates from the centre of the particle, which will affect the performance of the displacement detection. In this paper, we detect the radial displacement of the particle by utilizing the forward scattered light of the detection beam from the particle. The effects of the lateral and axial offsets between the detection beam focus and the particle centre on the displacement detection are analyzed by the simulation and experiment. The results show that the lateral offsets will decrease the detection sensitivity and linear range and aggravate the crosstalk between the x-direction signal and y-direction signal of QPD. The axial offsets also affect the detection sensitivity, an optimal axial offset can improve the sensitivity of the displacement detection substantially. In addition, the influence of system parameters, such as particle radius a, numerical aperture of the condenser NAc and numerical aperture of the objective NAo on the optimal axial offset are discussed. A combination of conventional optical tweezers instrument and a detection beam provides a more flexible working point, allowing for the active modulation of the sensitivity and linear range of the displacement detection. This work would be of great interest for improving the accuracy of the displacement and force detection performed by the optical tweezers.Comment: 10 pages,11 figure

Security Analysis of RAPP An RFID Authentication Protocol based on Permutation

One of the key problems in Radio Frequency Identification(RFID) is security and privacy. Many RFID authentication protocols have been proposed to preserve security and privacy of the system. Nevertheless, most of these protocols are analyzed and it is shown that they can not provide security against some RFID attacks. RAPP is a new ultralightweight authentication protocol with permutation. In RAPP, only three operations are involved: bitwise XOR, left rotation and permutation. In this paper, we give an active attack on RAPP. We first collect some authentication messages through impersonating valid tag and readers; Then we forge valid reader to communicate with the tag about times. Using the property of the left rotation and permutation operation, we can deduce the relationship of bits of random number or secret keys at different positions, thus obtain all the secret shared by the reader and the tag