Enzyme catalytic resonance scattering spectral detection of trace hydrogen peroxide using guaiacol as substrate

Hydrogen peroxide oxidized guaiacol to form tetramer particles that exhibited a strong resonance scattering (RS) peak at 530 nm in the presence of horseradish peroxidase (HRP) in citric acid-Na2HPO4 buffer solution of pH 4.4. The RS peak increased when the concentration of hydrogen peroxide increased. The increased RS intensity (ΔI530 nm) was linear to the hydrogen peroxide concentration in the range of 0.55-27.6 μM, with a linear regression equation of ΔI530 nm = 17.1C + 1.6, a relative coefficient of 0.9996 and a detection limit of 0.03 μM H2O2. This proposed method was applied to detect hydrogen peroxide in rain water, with sensitivity, selectivity, rapidity, and recovery of 98.0-104 %.KEY WORDS: HRP, H2O2, Guaiacol, Resonance scattering spectral method Bull. Chem. Soc. Ethiop. 2011, 25(2), 161-168. 

Andrographolide Alleviates Acute Brain Injury in a Rat Model of Traumatic Brain Injury: Possible Involvement of Inflammatory Signaling

Neuroinflammation plays an important role in secondary injury after traumatic brain injury (TBI). Andrographolide (Andro), a diterpenoid lactone isolated from Andrographis paniculata, has been demonstrated to exhibit anti-inflammatory activity in neurodegenerative disorders. This study therefore aimed to investigate the potential neuroprotective effects of Andro after TBI and explore the underlying mechanisms. In our study, we used a weight-dropped model to induce TBI in Sprague–Dawley rats, the neurological deficits were assessed using modified neurological severity scores, Fluoro-Jade B (FJB) and terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining were employed to examine neuronal degeneration and apoptosis after TBI, immunofluorescence was designed to investigate microglial activation. Quantitative Real-time PCR and ELISA were conducted to detect the expression levels of pro-inflammatory cytokines, Western blot was used to examine the expression level of proteins of relative signaling pathway. Our results showed that after Andro administration, the neurological deficit was attenuated, and the cerebral edema and apoptosis in brain tissues were also decreased following TBI. Both microglial activation and the expression of pro-inflammatory cytokines were significantly inhibited by Andro after TBI. Moreover, Andro inhibited NF-κB p65 subunit translocation and decreased the expression levels of phosphorylated extracellular signal regulated kinase (ERK) and p38 MAPK after TBI. Altogether, this study suggests that Andro could improve neurobehavioral function by inhibiting NF-κB and MAPK signaling pathway in TBI, which might provide a new approach for treating brain injury

<b>Enzyme catalytic resonance scattering spectral detection of trace hydrogen peroxide using guaiacol as substrate</b>

Hydrogen peroxide oxidized guaiacol to form tetramer particles that exhibited a strong resonance scattering (RS) peak at 530 nm in the presence of horseradish peroxidase (HRP) in citric acid-Na2HPO4 buffer solution of pH 4.4. The RS peak increased when the concentration of hydrogen peroxide increased. The increased RS intensity (ΔI530 nm) was linear to the hydrogen peroxide concentration in the range of 0.55-27.6 μM, with a linear regression equation of ΔI530 nm = 17.1C + 1.6, a relative coefficient of 0.9996 and a detection limit of 0.03 μM H2O2. This proposed method was applied to detect hydrogen peroxide in rain water, with sensitivity, selectivity, rapidity, and recovery of 98.0-104 %

Unix Domain Sockets Applied in Android Malware Should Not Be Ignored

Increasingly, malicious Android apps use various methods to steal private user data without their knowledge. Detecting the leakage of private data is the focus of mobile information security. An initial investigation found that none of the existing security analysis systems can track the flow of information through Unix domain sockets to detect the leakage of private data through such sockets, which can result in zero-day exploits in the information security field. In this paper, we conduct the first systematic study on Unix domain sockets as applied in Android apps. Then, we identify scenarios in which such apps can leak private data through Unix domain sockets, which the existing dynamic taint analysis systems do not catch. Based on these insights, we propose and implement JDroid, a taint analysis system that can track information flows through Unix domain sockets effectively to detect such privacy leaks

Migration of Leaked Oil Vapor in Underground Water-Sealed Oil Storage Cavern Considering the Influence of Fractures

During the operation of underground water-sealed oil storage caverns, a large amount of oil vapor is generated due to volatilization. Oil vapor can easily leak into the surrounding rock, and fractures in the surrounding rock are usually the dominant channels for oil vapor leakage. To study the influence of fractures on oil vapor leakage and migration in underground water-sealed oil storage caverns during the oil storage period, a gas–liquid two-phase flow model of the fracture–pore dual medium in fractured rock mass was established. The program was implemented on the COMSOL platform by using weak-form PDE (partial differential equation). Then, taking an underground water-sealed cavern of an oil reserve as an example, the influence of the characteristic parameters of a single fracture on the evolution process of oil vapor leakage and migration during the oil storage period of the underground water-sealed oil storage cavern was studied. The results were further applied to the Huangdao underground oil depot project. The results show that the spatial distribution of oil vapor leakage is mainly affected by fractures. Through parameter sensitivity analysis, it was found that the geometric characteristic parameters of fractures will have a certain impact on the migration field of oil vapor leakage in underground caverns. Specifically, fracture permeability (kf), fracture width (df), and fracture inclination (θ) are positively correlated with oil vapor leakage parameters (oil vapor leakage range and leakage volume), while the distance between the fracture and the middle cavern (s) is negatively correlated with oil vapor leakage parameters (oil vapor leakage range and leakage volume). The relative influence of fracture geometry parameters on the migration process of oil vapor leakage during the oil storage period of the underground water-sealed oil storage cavern is in the following order: kf> df> s > θ. Engineering application shows that the existence of fractures affects the spatial distribution of oil vapor leakage and migration, and the relationship between oil vapor leakage parameters and oil storage operation time is a positive power function. The gas–liquid two-phase flow model of the fracture–pore dual medium in fractured rock mass developed in this study could offer a numerical simulation tool to assess and mitigate the risk of oil vapor leakage. The research conclusions can provide some references for related problems encountered in similar projects

Load Rejection Transient Process Simulation of a Kaplan Turbine Model by Co-Adjusting Guide Vanes and Runner Blades

To obtain the flow mechanism of the transient characteristics of a Kaplan turbine, a three-dimensional (3-D) unsteady, incompressible flow simulation during load rejection was conducted using a computational fluid dynamics (CFD) method in this paper. The dynamic mesh and re-meshing methods were performed to simulate the closing process of the guide vanes and runner blades. The evolution of inner flow patterns and varying regularities of some parameters, such as the runner rotation speed, unit flow rate, unit torque, axial force, and static pressure of the monitored points were revealed, and the results were consistent with the experimental data. During the load rejection process, the guide vane closing behavior played a decisive role in changing the external characteristics and inner flow configurations. In this paper, the runner blades underwent a linear needle closure law and guide vanes operated according to a stage-closing law of &#8220;first fast, then slow,&#8222; where the inflection point was t = 2.3 s. At the segment point of the guide vane closing curve, a water hammer occurs between guide vanes and a large quantity of vortices emerged in the runner and the draft tube. The pressure at the measurement points changes dramatically and the axial thrust rises sharply, marking a unique time in the transient process. Thus, the quality of a transient process could be effectively improved by properly setting the location of segmented point. This study conducted a dynamic simulation of co-adjustment of the guide vanes and the blades, and the results could be used in fault diagnosis of transient operations at hydropower plants

Resonance Rayleigh Scattering and SERS Spectral Detection of Trace Hg(II) Based on the Gold Nanocatalysis

Mercury (Hg) is a heavy metal pollutant, there is an urgent need to develop simple and sensitive methods for Hg(II) in water. In this article, a simple and sensitive resonance Rayleigh scattering (RRS) method was developed for determination of 0.008–1.33 µmol/L Hg, with a detection limit of 0.003 μmol/L, based on the Hg(II) regulation of gold nanoenzyme catalysis on the HAuCl4-H2O2 to form gold nanoparticles (AuNPs) with an RRS peak at 370 nm. Upon addition of molecular probes of Victoria blue B (VBB), the surface-enhanced Raman scattering (SERS) peak linearly decreased at 1612 cm−1 with the Hg(II) concentration increasing in the range of 0.013–0.5 μmol/L. With its good selectivity and good accuracy, the RRS method is expected to be a promising candidate for determining mercury ions in water samples

Numerical Study on Flow Characteristics in a Francis Turbine during Load Rejection

Labyrinth seals are not usually included in the numerical models of hydraulic machinery to simplify the geometric modeling, and thereby reduce the calculation burden. However, this simplification affects the numerical results, especially in the load rejection process, because disc friction losses, volume losses, and pressure fluctuations in the seal ring (SR) clearance passage are neglected. This paper addresses the issue by considering all of the geometrical details of labyrinth seals when conducting multiscale flow simulations of a high head Francis turbine under a transient load rejection condition using the commercial software code. A comparison of the numerical results that were obtained with the experimental testing data indicates that the calculated values of both torque and mass discharge rate are 8.65% and 5% slightly less than the corresponding values that were obtained from experimental model testing, respectively. The obtained pressure fluctuations of the Francis turbine in the vaneless zone and the draft tube appear to more closely match with the experimental test data when including SR clearance. Moreover, the flow rates through SR clearance passages were very small, but the pressure fluctuations among them were significantly enhanced under the minimal load condition. The numerical model with SR clearance can more accurately reflect the fact that the water thrust on the runner only fluctuates from 800 N to 575 N during the load rejection process, even though the water thrust on the blades varies from &minus;220 N to 1200 N. Therefore, multiscale flow study is of great significance in understanding the effect of clearance flow on the load rejection process in the Francis turbine

Comparative network analysis reveals the dynamics of organic acid diversity during fruit ripening in peach (Prunus persica L. Batsch)

Abstract Background Organic acids are important components that determine the fruit flavor of peach (Prunus persica L. Batsch). However, the dynamics of organic acid diversity during fruit ripening and the key genes that modulate the organic acids metabolism remain largely unknown in this kind of fruit tree which yield ranks sixth in the world. Results In this study, we used 3D transcriptome data containing three dimensions of information, namely time, phenotype and gene expression, from 5 different varieties of peach to construct gene co-expression networks throughout fruit ripening of peach. With the network inferred, the time-ordered network comparative analysis was performed to select high-acid specific gene co-expression network and then clarify the regulatory factors controlling organic acid accumulation. As a result, network modules related to organic acid synthesis and metabolism under high-acid and low-acid comparison conditions were identified for our following research. In addition, we obtained 20 candidate genes as regulatory factors related to organic acid metabolism in peach. Conclusions The study provides new insights into the dynamics of organic acid accumulation during fruit ripening, complements the results of classical co-expression network analysis and establishes a foundation for key genes discovery from time-series multiple species transcriptome data