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A highly sensitive electrochemical biosensor was manufactured with triple synergistic catalysis to detect hydrogen peroxide (H

Currently, the exploitation of Baode Block as a biogenic coal-bed gas field has been in the later stage of stable production; hence, exploration and activation of microbial gas production are of great practical significance for the enhancement and stabilization of block production. Pretreatment is the key process to improve anaerobic biodegradation performance and increase yield and production rate of gas. In this study, we examine physical, chemical, and biological pretreatment methods and compare their effectiveness toward microbial gas production in the coal seam. The obtained results indicate that: (1) grinding can enhance contact between the coal sample and bacteria liquid, and coal powder has greater gas-producing performance than the coal lump. (2) Chemical pretreatment of coal samples using acid and base can enhance gas production capacity. NaOH treatment has better gas-producing performance than HCl treatment, and the activity of microbial flora is higher after treatment. (3) Biological pretreatment can greatly enhance the microbial degradation of coal bed. The highest gas yield after white rot fungus pretreatment is 11.65 m

Regular expression denial of service (ReDoS)— which exploits the super-linear running time of matching regular expressions against carefully crafted inputs—is an emerging class of DoS attacks to web services. One challenging question for a victim web service under ReDoS attacks is how to quickly recover its normal operation after ReDoS attacks, especially these zero-day ones exploiting previously unknown vulnerabilities.In this paper, we present RegexNet, the first payload-based, automated, reactive ReDoS recovery system for web services. RegexNet adopts a learning model, which is updated constantly in a feedback loop during runtime, to classify payloads of upcoming requests including the request contents and database query responses. If detected as a cause leading to ReDoS, RegexNet migrates those requests to a sandbox and isolates their execution for a fast, first-measure recovery.We have implemented a RegexNet prototype and integrated it with HAProxy and Node.js. Evaluation results show that RegexNet is effective in recovering the performance of web services against zero-day ReDoS attacks, responsive on reacting to attacks in sub-minute, and resilient to different ReDoS attack types including adaptive ones that are designed to evade RegexNet on purpose.

In this study we show for the first time that a reduced graphene oxide (rGO) carrier has a 15-fold higher catalysis rate than graphene oxide (GO) in Ag+ reduction. Based on this, we constructed a tumor microenvironment-enabled in situ silver-based electrochemical oncolytic bioreactor (SEOB) which unlocked an Ag+ prodrug to generate silver nanoparticles and inhibited the growth of various tumors. In this bioreactor system, intratumoral H2O2 acted as the reductant and the rGO carrier acted as the catalyst. Chelation of aptamers to this prodrug increased the production of silver nanoparticles by tumor cells, especially in the presence of Vitamin C, which broke down in tumor cells to supply massive amounts of H2O2. Consequently, highly efficient silver nanoparticle-induced apoptosis was observed in HepG2 and A549 cells in vitro and in HepG2- and A549-derived tumors in vivo. The apoptosis was associated with ROS-induced changes in mitochondrial membrane potential and DNA damage. The specific aptamer targeting and intratumoral silver nanoparticle production guaranteed excellent biosafety, with no damage to normal cells, because the Ag+ prodrug was specifically unlocked in tumors. More significantly, there was no evident tissue damage in monkeys, which greatly increases the clinical translation potential of the SEOB system.

Distributed storage employs replication to mask failures and improve availability. However, these systems typically exhibit a hard tradeoff between consistency and performance. Ensuring consistency introduces coordination overhead, and as a result the system throughput does not scale with the number of replicas. We present Harmonia, a replicated storage architecture that exploits the capability of new-generation programmable switches to obviate this tradeoff by providing near-linear scalability without sacrificing consistency. To achieve this goal, Harmonia detects read-write conflicts in the network, which enables any replica to serve reads for objects with no pending writes. Harmonia implements this functionality at line rate, thus imposing no performance overhead. We have implemented a prototype of Harmonia on a cluster of commodity servers connected by a Barefoot Tofino switch, and have integrated it with Redis. We demonstrate the generality of our approach by supporting a variety of replication protocols, including primary-backup, chain replication, Viewstamped Replication, and NOPaxos. Experimental results show that Harmonia improves the throughput of these protocols by up to 10 x for a replication factor of 10, providing near-linear scalability up to the limit of our testbed.

Tensile properties and work-hardening behaviours of Al–Cu alloys both unmodified and modified by Al84Ni10La6 metallic glass were investigated in detail. The results showed that the Al–Cu alloy modified by 0.4 wt.% Al84Ni10La6 metallic glass showed superior tensile properties (a high tensile strength of 510 MPa and ductility of 14.8%) and impressive work-hardening capacity (Hc was 0.522). It is attributed to refined α-Al dendritic grains, finer θ′ precipitates in grain interiors and the Al11La3 at grain boundaries.

The Al–Cu alloys inoculated by metallic glasses Ni60Nb25Ti15, Fe79.58B11.16Si9.26 and Zr55Cu30Al10Ni5 were investigated, respectively. The results revealed that α-Al grains of the inoculated alloys were obviously refined since the crystallization NiTi, Fe2B, ZrCu(B2) and Zr2Cu from these metallic glasses can act as the heterogeneous nucleation sites. Compared with Zr55Cu30Al10Ni5, Ni60Nb25Ti15 and Fe79.58B11.16Si9.26 metallic glass inoculants have significantly higher effective inoculation time (∼30 min). Actually, the effective inoculation time of these metallic glasses inoculants is with a sequence of Ni60Nb25Ti15 > Fe79.58B11.16Si9.26 > Zr55Cu30Al10Ni5, which is mainly because the melt points of Fe2B and NiTi are higher than that of Zr2Cu and ZrCu(B2).

At elevated temperatures, the inoculated Al–Cu alloys by Zr-based metallic glass showed the superior tensile properties than the uninoculated alloys, such as: at 433 K and 10 −1 s −1 , the strength and ductility of the inoculated alloys were 445 MPa and 14.8%, 112 MPa and 3.9% higher than the uninoculated alloys, respectively; at 493 K and 10 −1 s −1 , the strength and ductility of the inoculated alloys were 340 MPa and 16.5%, with the increment of 36 MPa and 9.8% than the uninoculated alloys, respectively. This is attributed to the smaller grain size and more homogeneously distributed θ ′ precipitates.

A significant refining effect of α-Al grains from 200 μm to 42 μm can be achieved by addition of 0.1 wt.% FeBSi metallic glass, which is mainly attributed to the crystallization of Fe2B phase being able to act as the heterogeneous nucleation sites of α-Al grains during solidification. Within an inoculation time of 30 min, the inoculated Al–Cu alloys remain a fine grained structure. Moreover, the strength and ductility of the inoculated alloys are simultaneously improved. The enhanced properties of Al–Cu alloy inoculated by metallic glass are mainly due to the refined α-Al grains, the small θ′ precipitates distributed homogeneously in grain interior and the formation of the nano-sized AlCuFeMn phase. This study provides a high-efficiency and cost-effective processing technique of refinement in this alloy, and at the same time, broadens the industry application of metallic glass.

A new strategy for simultaneously increasing strength and ductility of the Al–Cu alloys was reported here, that is: the inoculated Al–Cu alloys by Zr55Cu30Al10Ni5 metallic glass showed the superior strength and ductility than the uninoculated alloy. The highest tensile strength and ductility of the inoculated alloy by Zr55Cu30Al10Ni5 metallic glass were 569 MPa and 11.1%, improved by 15.3% and 58.5%, respectively, than those of the uninoculated alloys. These enhanced properties are suggested to be induced by the refined α-Al grains and the smaller nano-sized θ′ precipitates.

Immersion tests and electrochemical experiments were performed to study the room temperature corrosion behavior of the unmodified and modified Al–Cu alloys with using RE x O y (Pr x O y and La x O y ) in 3.5 wt.% NaCl solution and pH = 4 acid solution. The results showed that the modified Al–Cu alloys have superior corrosion resistance than the unmodified alloy in both solutions. However, a contrary variation trend of corrosion resistance with increasing RE x O y content was found in these two solutions. In 3.5 wt.% NaCl solution, the corrosion resistance of the modified alloys increases gradually with increasing RE x O y content, but deceases gradually in pH = 4 acid solution. The reason for this contrary trend was discussed.

The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al11Pr3 phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al11Pr3 phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modified alloy at elevated temperatures.

Zr55Cu30Al10Ni5 bulk metallic glass (BMG) and its composites with different oxygen contents from 0.1 at% to 1.0 at% were prepared by copper-mold-casting. Primary crystallizing phases with different microstructures and volume fractions were produced in these alloys due to the incorporation of different oxygen contents. The X0.1 monolithic BMG has no plasticity. The X0.2, X0.3 and X0.4 composites contained the tiny crystallites or crystalline phases show some plasticity. The X0.2 composites exhibits the largest fracture strain of 8.10%. It is believed that the presence of the randomly distributed nanometer-sized crystallites in these alloys is effective to seed the formation and propagation of multiple shear bands. As the oxygen content increases from 0.5 to 1.0 at%, volume fraction of the crystalline phases in the composites increases remarkably, and the yield strength, fracture strength and fracture strain decreased, while Θ, Hc, K and n increased. The X0.5, X0.6, X0.8 and X1.0 composites display work-hardening and plastic deformation. The work-hardening effect and the plasticity result from the continuous martensitic transformation, the dislocation multiplication in the crystalline phase and the interactions of shear bands during deformation.

In the present work, a sensitive electrochemical aptasensor was designed for the detection of adenosine triphosphate (ATP) with hemin/graphene oxide nanosheets (HGNs). Firstly, the ATP aptamer was self-assembled on gold electrode surface, and then HGNs were captured to the modified electrode by π-π stacking. The captured HGNs could catalyze the disproportionation reaction of H2O2, and produced a detectable electrochemical signal by chronoamperometry. ATP was competitively bound to aptamer which led to the release of HGNs from the electrode surface after adding ATP. The decrease of the electrochemical signal, which was calculated by the difference of amperometric responses before and after incubation of ATP, provided a quantitative signal for ATP detection. A linear correlation was achieved between the difference of the amperometric responses and the logarithmic concentration of ATP ranging from 0.5 to 100 nM with a detection limit of 0.08 nM. Besides, the aptasensor also exhibited good selectivity toward ATP against other analogs.

A highly sensitive non-enzymatic electrochemical sensor based on platinum nanoparticles/reduced graphene oxide-chitosan-ferrocene carboxylic acid nano-hybrids (Pt NPs/RGO-CS-Fc biosensor) was developed for the measurement of hydrogen peroxide (H2O2). The RGO-CS-Fc nano-hybrids was prepared and characterized by UV-vis spectrum, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectrometer and electrochemical impedance spectroscopy. Under optimal experimental conditions, the Pt NPs/RGO-CS-Fc biosensor showed outstanding catalytic activity toward H2O2 reduction. The current response of the biosensor presented a linear relationship with H2O2 concentration from 2.0×10(-8)M to 3.0×10(-6)M with a correlation coefficient of R(2)=0.9968 and with logarithm of H2O2 concentration from 6.0×10(-6)M to 1.0×10(-2)M with a correlation coefficient of R(2)=0.9887, the low detection limit of 20nM was obtained at the signal/noise (S/N) ratio of 3. Moreover, the Pt NPs/RGO-CS-Fc biosensor exhibited excellent anti-interference capability and reproducibility for the detection of H2O2. The biosensor was also successfully applied for the detection of H2O2 from living cells containing normal and cancer cells. All these results prove that the Pt NPs/RGO-CS-Fc biosensor has the potential application in clinical diagnostics to evaluate oxidative stress of different living cells.

Through multi–modification with PrxOy and LaxOy, the tensile strength and elongation of casting Al−Cu alloy can reach to 580 MPa and 10.5%, increased by 26% and 50% respectively than those of the unmodified alloy. Simultaneous increase in the tensile strength and elongation of the multi-modified alloys is suggested to be induced by the refined α-Al dendrites, the formation of Al−RE intermetallic compounds at the grain boundaries, and the most important, more homogeneously distributed nano-scale θ′ precipitates with higher diameter/thickness ratio.

The hardness and thermal stability are the important problems of the cast Al–Cu alloy related to the microstructural changes. In order to increase the possibilities of high temperature applications of the cast Al–Cu alloy, it is necessary to gain a more detail understanding of the correlation between the age hardening and the microstructure in the cast Al–Cu alloy, and the thermal stability of the θ′ precipitates at elevated temperatures. The aim of this work is to investigate the effects of La addition on the age hardening behavior and precipitation kinetics in the Al–Cu alloy in the temperature range from 435 to 523 K. The results indicated that La addition considerably increases the number of the θ′ precipitates and decreases their sizes, which results in the enhanced age hardening effect. The precipitation kinetics analysis showed that the activation energy (13 kJ/mol) of the θ′ precipitate nucleation of the modified alloy is smaller than that (19 kJ/mol) of the unmodified alloy. The decrease in the activation energy of the θ′ precipitate nucleation can be explained with both the enhanced nucleation process due to La/Cu/vacancy aggregating and the increased interaction between Al and Cu atoms.