High Concentrations Of Hydrogen Peroxide Research Articles

Differential Sensitivity of Two Endothelial Cell Lines to Hydrogen Peroxide Toxicity: Relevance for In Vitro Studies of the Blood-Brain Barrier.

Oxidative stress (OS) has been linked to blood–brain barrier (BBB) dysfunction which in turn has been implicated in the initiation and propagation of some neurological diseases. In this study, we profiled, for the first time, two endothelioma cell lines of mouse brain origin, commonly used as in vitro models of the blood–brain barrier, for their resistance against oxidative stress using viability measures and glutathione contents as markers. OS was induced by exposing cultured cells to varying concentrations of hydrogen peroxide and fluorescence microscopy/spectrometry was used to detect and estimate cellular glutathione contents. A colorimetric viability assay was used to determine changes in the viability of OS-exposed cells. Both the b.End5 and bEnd.3 cell lines investigated showed demonstrable content of glutathione with a statistically insignificant difference in glutathione quantity per unit cell, but with a statistically significant higher capacity for the b.End5 cell line for de novo glutathione synthesis. Furthermore, the b.End5 cells demonstrated greater oxidant buffering capacity to higher concentrations of hydrogen peroxide than the bEnd.3 cells. We concluded that mouse brain endothelial cells, derived from different types of cell lines, differ enormously in their antioxidant characteristics. We hereby recommend caution in making comparisons across BBB models utilizing distinctly different cell lines and require further prerequisites to ensure that in vitro BBB models involving these cell lines are reliable and reproducible.

Redox requirements for ubiquitin-like urmylation of Ahp1, a 2-Cys peroxiredoxin from yeast

The yeast peroxiredoxin Ahp1, like related anti-oxidant enzymes in other species, undergoes urmylation, a lysine-directed conjugation to ubiquitin-like modifier Urm1. Ahp1 assembles into a homodimer that detoxifies peroxides via forming intersubunit disulfides between peroxidatic and resolving cysteines that are subsequently reduced by the thioredoxin system. Although urmylation coincides with oxidative stress, it is unclear how this modification happens on a molecular level and whether it affects peroxiredoxin activity. Here, we report that thioredoxin mutants decrease Ahp1 urmylation in yeast and each subunit of the oxidized Ahp1 dimer is modified by Urm1 suggesting coupling of urmylation to dimerization. Consistently, Ahp1 mutants unable to form dimers, fail to be urmylated as do mutants that lack the peroxidatic cysteine. Moreover, Ahp1 urmylation involves at least two lysine residues close to the catalytic cysteines and can be prevented in yeast cells exposed to high organic peroxide concentrations. Our results elucidate redox requirements and molecular determinants critical for Ahp1 urmylation, thus providing insights into a potential link between oxidant defense and Urm1 utilization in cells.

Seminal plasma has limited counteracting effects following induction of oxidative stress in donkey spermatozoa.

The aim of this study was to evaluate the response of donkey spermatozoa to oxidative stress induced by hydrogen peroxide, and to determine whether the presence of seminal plasma modulates the sperm response to that stress. Nine ejaculates were collected, extended in skim milk extender and split into two aliquots. Seminal plasma was removed from the first but not second aliquot. Samples were subsequently split into four aliquots supplemented with different concentrations of commercial hydrogen peroxide (0, 100 and 250µM and 50mM). Aliquots were incubated at 37°C under aerobic conditions and several sperm parameters, namely motility, viability, intracellular levels of peroxides and superoxides and mitochondrial membrane potential, were evaluated at 0, 1 and 3h. Exposure to hydrogen peroxide markedly decreased sperm motility but had much less of an effect on sperm viability, mitochondrial membrane potential and intracellular reactive oxygen species levels. A protective effect of seminal plasma against the loss of sperm motility was not apparent, but some kinetic parameters and relative levels of superoxides were better maintained when seminal plasma was present together with high concentration of hydrogen peroxide. In conclusion, oxidative stress induced by hydrogen peroxide reduces donkey sperm motility and has a less apparent effect on other sperm parameters. Finally, seminal plasma is only able to partially ameliorate the detrimental effect of this induced stress.

Molecular domino reactor built by automated modular synthesis for cancer treatment.

Rationale: A cascade, or domino, reaction consists of two, or more, consecutive reactions such that subsequent reactions occur only if some chemical functionality has first been established in the prior step. However, while construction of predesigned and desired molecular domino reactors in a tailored manner is a valuable endeavor, it is still challenging.Methods: To address this challenge, we herein report an aptamer-based photodynamic domino reactor built through automated modular synthesis. The engineering of this reactor takes advantage of the well-established solid-phase synthesis platform to incorporate a photosensitizer into G-quadruplex/ hemin DNAzyme at the molecular level.Results: As a proof of concept, our photodynamic domino reactor, termed AS1411/hemin- pyrochlorophyll A, achieves in vivo photodynamic domino reaction for efficient cancer treatment by using a high concentration of hydrogen peroxide (H2O2) in the tumor microenvironment (TME) to produce O2, followed by consecutive generation of singlet oxygen (1O2) using the pre-produced O2. More specifically, phosphoramidite PA (pyrochlorophyll A) is coupled to aptamer AS1411 to form AS1411-PA ApDC able to simultaneously perform in vivo targeted imaging and photodynamic therapy (PDT). The insertion of hemin into the AS1411 G-quadruplex was demonstrated to alleviate tumor hypoxia by decomposition of H2O2 to produce O2. This was followed by the generation of 1O2 by PA to trigger cascading amplified PDT.Conclusion: Therefore, this study provides a general strategy for building an aptamer-based molecular domino reactor through automated modular synthesis. By proof of concept, we further demonstrate a novel method of achieving enhanced PDT, as well as alleviating TME hypoxia at the molecular level.

A mitochondrial-targetable dual functional near-infrared fluorescent probe to monitor pH and H2O2 in living cells and mice.

A lower pH level and high hydrogen peroxide (H2O2) concentration in mitochondria is closely associated with a variety of diseases including cancer and inflammation. Thus, determination of changes in the level of acidic pH and H2O2 is of great importance and could provide new insights into the key functions under both physiological and pathological conditions. Herein, we present a novel mitochondria-targetable probe NIR-pH-H2O2, as the first near infrared (NIR) fluorescent small molecule, to monitor changes of endogenous pH (pka = 6.17) and H2O2 with high sensitivity, good compatibility and low cytotoxicity. Futhermore, it was successfully employed to monitor pH and H2O2 in a mouse acute inflammation model. These results demonstrate that NIR-pH-H2O2 is a novel bifunctional mitochondrial-targeted NIR probe to sense acidic pH and H2O2in vitro and in vivo, indicating its huge potential for the diagnosis of pH and H2O2-related diseases.

Chemical signature detection of groundwater and geothermal waters for evidence of crustal deformation along fault zones

Common crustal igneous and high grade metamorphic rocks contain peroxy defects which remain dormant until the rock experiences stress upon deformation. Stress activated peroxy defects form highly reactive oxygen species (ROS) at the rock-water interface observed in both terrestrial and extraterrestrial rock samples. The ROS complex is formed upon rock fluid interaction when groundwater combines with the ROS to produce hydrogen peroxide giving an indirect measure of the underlying rock stress and crustal deformation along active faults. The average concentration of hydrogen peroxide from the Sohna thermal spring water falling along the active Sohna fault and geothermal field was measured to be ~ 0.53 ± 0.014 mg/l. Similar average concentration was also recorded from borewell sample north of the spring (~0.56 ± 0.017 mg/l) within the same geothermal field. Lower concentration of hydrogen peroxide was recorded within samples collected from hard rock aquifers outside the geothermal field and the active fault zone (~0.138 ± 0.095 mg/l). The detailed analysis suggests that the presence of hydrogen peroxide is largely dependent on the circulation pattern through the interconnected fractures/joints within the quartzite bedrock lying adjacent to the fault plane. Laboratory analysis results also show high hydrogen peroxide concentration within two borewell samples falling adjacent to the epicentre of a shallow microtremor event within the hard rock region falling alongside a lineament along the Delhi hard rock mega fold. Rock water interaction post stress activation of peroxy defects and formation of ROS has therefore been inferred to be responsible for the formation of hydrogen peroxide at the rock water interface within these zones. This pilot study provides scientific field evidence that hydrogen peroxide concentrations within groundwaters might offer prospects for seismic stress estimation and crustal deformation along seismically active zones.

Presence of X-ray Induced High Concentrated Hydrogen Peroxide Clusters

Presence of X-ray Induced High Concentrated Hydrogen Peroxide Clusters

INFLUENCE OF DIFFERENT METHODS OF WHITENING ON THE STRUCTURE OF HARD TISSUES OF TEETH

Nowadays 74% of people believe that an imperfect smile has a negative impact on their careers, and 92% believe that it is one that contributes to success in their personal lives. The desire of patients to have an aesthetically perfect smile has always aroused great interest from dentists and has led to the active development of such a trend in aesthetic dentistry, such as teeth whitening. The color of the crowns of teeth and the inherent color characteristics play an important role in the perception of the appearance of the person, the formation of his image and self-esteem. Therefore, they affect the quality of life of a person due to his dental health. There are 5 main treatments for altered teeth: microabrasion, teeth whitening, direct restoration of composites, veneering, restoration of ceramic and metal-ceramic crowns. In recent years, conservative treatments, which include different types of whitening, have been favored to achieve maximum aesthetic results in the correction of altered teeth. For whitening, a considerable number of different remedies are offered that allow the tooth color to change relatively quickly. Nowadays, the world of dental practice is increasingly paying attention to the development of more cost-effective methods that meet the aesthetic needs of patients. The most common procedure for improving the color of the crowns of teeth today is whitening, which does not affect the reduction of the volume of hard tissues of the tooth. Teeth whitening is a restoration of the natural color of the teeth with the application of a chemical agent that oxidizes the organic pigments of the hard tissues of the tooth. Bleaching process is possible due to the ability of the active chemical components ( carbamide peroxide, hydrogen peroxide) to penetrate into enamel and dentin to all parts of the tooth. These substances break down into oxygen radicals, which destroy the colored pigments, the formation of which leads to discoloration of the teeth. The structure of the tooth does not change. Nowadays, home, professional and combined teeth whitening are widely used. The effect of bleaching is analyzed using a scanning electron microscope. Most studies did not report significant changes in the surface morphology of enamel after bleaching with low concentrations of urea peroxide and hydrogen peroxide. Similarly, studies evaluating the effects of higher concentrations of hydrogen peroxide (35%) and carbamidee peroxide (35%) have also reported no significant changes in the morphology of the enamel surface. In general, it is obvious that tooth sensitivity is a common clinical side effect after a teeth whitening procedure. However, the sensitivity is transient and disappears shortly after the bleaching procedure has been stopped.

Fenton\u2019s reaction-based chemical oxidation in suboptimal conditions can lead to mobilization of oil hydrocarbons but also contribute to the total removal of volatile compounds

Fenton’s reaction-based chemical oxidation is in principle a method that can be utilized for all organic fuel residues thus making it a potential all-purpose, multi-contaminant, in situ application for cases in which storage and distribution of different types of fuels have resulted in contamination of soil or groundwater. Since peroxide breakdown reactions are also expected to lead to a physical transport of the target compound, this secondary physical removal, or rebound concentrations related to it, is prone to be affected by the chemical properties of the target compound. Also, since soil conditions are seldom optimal for Fenton’s reaction, the balance between chemical oxidation and transport may vary. In this study, it was found that, with a high enough hydrogen peroxide concentration (5 M), methyl tert-butyl ether–spiked groundwater could be treated even under suboptimal conditions for chemical mineralization. In these cases, volatilization was not only contributing to the total removal but also leading to rebound effects similar to those associated with air sparging techniques. Likewise for diesel, temporal transport from soil to the aqueous phase was found to lead to false positives that outweighed the actual remediation effect through chemical mineralization.

In vitro bleaching effect of hydrogen peroxide with different time of exposition and concentration on shear bond strength of orthodontic brackets to human enamel: A meta-analysis of in vitro studies

Controversy exists regarding the effect of bleaching on shear bond strength (SBS) of orthodontic brackets to enamel. This study aims to do a review and meta-analysis on the effect of bleaching with hydrogen peroxide on SBS according to the interval between bleaching and bonding to human enamel and the concentration of Hydrogen Peroxide. An electronic search of the literature was performed in Scopus, PubMed and Cochrane databases including CENTRAL and Cochrane library for relevant in vitro studies on the effect of bleaching with hydrogen peroxide on shear bond strength of human enamel, published until June 2018. Modified Cochrane Risk of Bias tool was used to assess the quality of the individual studies. AMSTAR tool was used for assessing the quality of the study. Nineteen studies were included in the qualitative analysis. Regardless of the interval between bleaching and bonding, reduction in SBS was not statistically significant when the hydrogen peroxide of less than 35% is used. Bleaching with 35% hydrogen reduces SBS when the bonding is conducted immediately (P<0.0001) or the time interval was shorter than one day (P<0.0005). On the other hand, use of high dose hydrogen peroxide resulted in a statistically significant reduction in SBS irrespective of the time interval between the procedures (P<0.05 for all categories of time interval). Bleaching with hydrogen peroxide decreases the SBS of brackets in patients undergoing orthodontic treatment especially if the time interval between bleaching and bonding procedures is short and a high concentration of hydrogen peroxide is used.

A comparison between flow-through cathode and mixed tank cells for the electro-Fenton process with conductive diamond anode

This work focusses on the production of hydrogen peroxide and in the removal of bromacil by the electro-Fenton process using two different electrochemical cells: mixed tank cell (MTC) and flow-through cell (FTC). Both cells use boron doped diamond (BDD) as anode and carbon felt as cathode to promote the formation of hydrogen peroxide. In the case of the MTC, two surface area ratios, Acathode/Aanode, have been used. Results show that the H2O2 produced by MTC and FTCPSC increases with the time until a stabilization state. For the FTCPSC, the average hydrogen peroxide concentration produced increases progressively with the current, while for MTC the maximum values are found in applying very low current densities. In addition, the FTCPSC provides higher concentrations of hydrogen peroxide for the same current density applied. Regarding the MTC, it can be stated that the higher the area of the cathode, the higher is the amount of H2O2 produced and the lower is the cell voltage (because of a more efficient current lines distribution). The initial oxidation of bromacil is very efficiently attained being rapidly depleted from wastewater. However, the higher production of hydrogen peroxide obtained by the FTCPSC cell does not reflect on a better performance of the electro-Fenton process. Thus, bromacil is better mineralized using the MTC cell with the lowest cathode area. This observation has been explained because larger concentrations of produced hydrogen peroxide seems to benefit the oxidation of intermediates and not the mineralization.

Enhancement of iron-mediated activation of persulfate using catechin: From generation of reactive species to atenolol degradation in water

Persulfate (PS) activation reaction, which forms sulfate radical (SO4−), can be used to degrade organic pollutants in water. However, a drawback of this reaction is that the regeneration of ferrous ions requires a high concentration of hydrogen peroxide (Fenton-like reaction) or use of UV radiation. Catechin (CAT), a non-toxic antioxidant of natural origin from tea, is used in this work to improve the sulfate radical-mediated degradation of atenolol (ATL, a model pollutant) in water using relatively low concentrations of reactive chemical species (less than 100 μM).To the best of the author's knowledge, the direct effect of CAT on the oxidation state of iron, which is promoted by the reduction of ferric into ferrous ions with the enhancement of SO4− formation in the presence of PS, is demonstrated for the first time. The enhancement versus inhibition effect of CAT and the chemical mechanism of the iron-based activation process are explained. Results show that UVA radiation, which is representative of solar light, accelerates the initial degradation of ATL by more than 30% through ferric iron photolysis. Finally, a reaction mechanism leading to the formation of hydroxyl radicals (HO) and SO4− is proposed considering the implication of different activation/reaction chemical steps.

Hydrogen peroxide measurements in subtropical aquatic systems and their implications for cyanobacterial blooms

Hydrogen peroxide is widely recognized as the most stable of the reactive oxygen species (ROS) produced by both biotic and abiotic pathways in natural waters. Its high reactivity in mediating redox transformations may, directly or indirectly, affect aquatic ecosystem functions, including primary productivity. However, environmental interactions between photoautotrophs, particularly cyanobacteria, and hydrogen peroxide are poorly understood. To gain a better understanding of hydrogen peroxide and cyanobacterial interactions, we determined the hydrogen peroxide concentrations in the presence and absence of cyanobacterial blooms in southwest Florida. Hydrogen peroxide concentrations were determined using a fast response amperometric hydrogen peroxide microelectrode. Our measurements ranged from 0 to 5.3 µM in freshwater bodies (ponds, lakes and the Caloosahatchee River) and 0 to 92.9 µM in rainwater. In general, hydrogen peroxide levels were highly associated with cyanobacterial bloom conditions, indicating the potential role of cyanobacteria in hydrogen peroxide production in freshwater. To determine the potential biodegradation of hydrogen peroxide during sample transportation in the dark condition, water samples were passed through 0.2 µm pore size filters immediately after sampling and compared with unfiltered water samples in the laboratory. We found that filtered water samples retained higher concentrations of hydrogen peroxide than unfiltered samples with a mean biodegradation rate of 44 ± 10.6 nmol/h. Out of a total of 26 samples, only one unfiltered sample showed a higher hydrogen peroxide concentration than the filtered samples. Overall, our study found the microelectrode technique could accurately measure hydrogen peroxide concentrations in the samples from various freshwater bodies. This measurement method revealed that hydrogen peroxide concentrations vary with temporal and spatial dynamics of cyanobacterial blooms.

Experimental investigation of the effect of nozzle throat diameter on the performance of a hybrid rocket motor with swirling injection of high-concentration hydrogen peroxide

One of the issues of using a normal graphite nozzle for the hybrid rocket propulsion is the serious throat erosion due to combustion with a higher O/F ratio. This may undermine the throttling capability of the hybrid rocket engine. In this study, we would like to address how the propulsion performance changes under the conditions of different nozzle throat diameters and O/F ratios. We designed and tested a 40-kgf class single-port hybrid rocket motor with the swirling injection of oxidizer, which utilizes the 90 wt% hydrogen peroxide and polypropylene (PP) as oxidizer and fuel, respectively. Three different diameters of graphite nozzle throat (10, 11, and 12 mm) were used to approximate various conditions of nozzle erosion, while the mass flow rates of the injected oxidizer were kept the same. The hot-fire test results indicated that the thrust was nearly the same even the nozzle throat diameters and O/F ratios were different. Especially, the discrepancies among the measured thrusts and oxidizer ISP under various test conditions were found to be less than 1%, which is highly beneficial for the purpose of the thrust control using mass flow rate control of the oxidizer for a hybrid rocket engine with swirling injection of high-concentration hydrogen peroxide.

In situ growth of hexagonal prism-like Ni(OH)2 microrods on nickel foam as binder-free electrodes

In this paper, we report in situ growth of hexagonal prism-like Ni(OH)2 microrods via one-step hydrothermal process, where nickel foam is directly oxidized in a high concentration hydrogen peroxide (H2O2) solution without additional nickel sources, surfactant, or post-treatment. The nickel foam not only serves as a nickel source but also as 3D scaffold for Ni(OH)2 growth to form binder-free electrodes. The in situ growth can ensure close contact between conductive Ni foam substrate and as-formed Ni(OH)2 microrods, providing efficient electron collection paths and electrochemical stability. Mass loading of Ni(OH)2 on nickel foam could be tailored by adjusting the concentration H2O2. Possible growth mechanism of hexagonal prism-like Ni(OH)2 microrods is discussed to understand the morphologies under various H2O2 concentrations. When works as a binder-free electrode, the Ni(OH)2-coated nickel foam exhibits a remarkable areal capacitance ~ 1.598 C cm−2 (560 C g−1) at a current density of 1 mA cm−2, relatively high rate capability with 57.14% areal capacitance retained at 10 mA cm−2, as well as better cycling stability with 72.9% areal capacitance remained after 3000 charge-discharge cycles. Such superior performance demonstrates that Ni(OH)2 microrods in situ grown on metallic nickel foam substrate might be a potential electrode material for electrochemical capacitors.

Paraoxonase 1 in bovine milk and blood as marker of subclinical mastitis caused by Staphylococcus aureus

The aim of this study was to determine serum lipid values and parameters of oxidative stress in blood and milk of cows with subclinical mastitis (SCM) caused by Staphylococcus aureus and to establish association between these parameters. The study was performed on total of 104 cows assigned into control group of healthy animals (n = 12) and two groups of cows with SCM, either SCM1 group (n = 37) with ˂ 1000 CFU/mL of S. aureus or SCM2 group (n = 55) with ≥1000 CFU/mL of causative agent in milk. Significantly lower serum concentrations of high density lipoprotein-cholesterol (HDLC) in SCM2 group and higher low density lipoprotein-cholesterol (LDL-C) in both SCM groups were recorded. Significantly lower paraoxonase-1 (PON1) activity and higher lipid hydroperoxides (LOOH) concentration in blood and milk were recorded in both groups of SCM cows vs control. In blood serum of cows from SCM2 group significantly higher concentrations of hydrogen peroxide (H2O2) and malondialdehyde (MDA), but significantly lower total antioxidative capacity (TAC) were obtained. In milk serum of SCM cows were detected significantly higher concentrations of H2O2 and MDA, but significantly lower TAC vs control. There was a significant positive correlation between PON1 in serum with HDLC, but negative correlation with LDL-C and LOOH. In milk, PON1 negatively correlated with LOOH and somatic cell counts (SCC). Strong positive correlation was obtained between PON1 in blood and milk. Oxidative stress and inflammatory reaction induced by SCM significantly lowered PON1 activity in blood and milk of affected cows.

Effect of cold atmospheric plasmas on bacteria in liquid: The role of gas composition

AbstractIn order to study the impact of different gas compositions on the bactericidal efficiency of cold atmospheric plasma jets, a device with a controlled atmosphere is built. Various mixtures of argon and helium with air are studied regarding their sterilizing effect onEscherichia coliin solution. Bacteria reduction rates react fundamentally different on addition of air in both gases. In case of helium, a distinct maximum for small admixtures is observed.Several diagnostic techniques were applied to the plasma. Stronger formation of peroxynitrous acid due to higher concentrations of hydrogen peroxide and nitrite is found to be responsible for the observed trends and differences. The presented findings are important for the development of efficient treatment devices.

Effect of fiber post space irrigation with different peracetic acid formulations on the bond strength and penetration into the dentinal tubules of self-etching resin cement

Statement of problemThe post space must be irrigated with solutions that do not interfere with the bond strength and enhance penetration into the dentinal tubules of self-etching resin cement. Which solution is best is unclear. Peracetic acid with different formulations appears to be a good option. PurposeThe purpose of this in vitro study was to evaluate the effect of irrigating the fiber post space by using 1% peracetic acid (PA) at low (LH) or high (HH) hydrogen peroxide concentration on the bond strength and penetration into the dentinal tubules of RelyX U200 self-etching resin cement. Material and methodsAfter intraroot preparation for fiber posts in 60 endodontically treated teeth, the specimens were divided into 4 groups (n=15) according to the irrigation protocol: CG (control), distilled water; NA (NaOCl), 2.5% sodium hypochlorite; LHPA, PA with a low concentration of hydrogen peroxide; and HHPA, PA with a high concentration of hydrogen peroxide. The fiber posts were then cemented with self-etching resin cement labeled with rhodamine. Cross sections of the thirds were obtained by confocal scanning microscopy and submitted to the push-out and cement penetration tests. The data obtained in the push-out tests were evaluated by using ANOVA and the Tukey post hoc test, and those data obtained in the confocal screening were evaluated by using the Kruskal-Wallis and Dunn (Bonferroni correction) tests (α=.05). ResultsBond strength values in the cervical third of the CG were higher than those in NA (P=.035) but similar to those of the other groups (P=.05). In the other thirds, CG and LHPA values were similar to one another (P=.05) but higher than those of NA and HHPA (P<.001). The penetration rate assessed by confocal scanning microscopy revealed similar results in the cervical third for all groups (P=.075), except for NA which provided the lowest penetration. In the remaining thirds, CG and LHPA provided the highest penetration rate (P=.015). ConclusionsThe LHPA group had no negative effects on the bond strength and penetration into the dentinal tubules of the self-etching resin cement.

Thrombus targeting aspirin particles for near infrared imaging and on-demand therapy of thrombotic vascular diseases

A blood clot (thrombus) is formed as a final product of the hemostatic process with two major components, a mesh of cross-linked fibrin and platelets activated by high concentration of hydrogen peroxide (H2O2). Thrombus formation impedes blood flow to brain and heart and is a principle cause of life-threatening diseases such as stroke and myocardial infarction. Aspirin has been widely used for the treatment and prevention of various cardiovascular diseases, but is unable to target a thrombus and scavenge a high level of H2O2. In this study, we report thrombus targeting aspirin polyconjugate particles (T-APP) as a near infrared imaging agent and on-demand therapeutic agent for thrombotic vascular diseases. T-APP were formulated from H2O2-activatable aspirin polyconjugate, fibrin-specific peptides and fluorescent IR780. In mouse models of tail bleeding and arterial thrombosis, T-APP targeted the thrombosed vessels rapidly with excellent specificity. T-APP also exerted highly strong antithrombotic activity in the thrombosed vessel by suppressing anti-inflammatory cytokines and inhibiting platelet activation. Based on the unique features such as specific thrombus targeting, H2O2 scavenging, and on-demand therapeutic actions, the rationally engineered T-APP have important ramifications on imaging and on-demand therapy of thrombotic disorders.

The Effect of Sealing Ring Gap on Hydrogen Peroxide Electric Pump

Chained decomposition will take place in terms of overheat of high concentration hydrogen peroxide, which will further cause explosion, in the electric pump pressurized liquid propellant rocket engine, which takes hydrogen peroxide of high concentration as oxidizing agent, the design of oxidant pump should consider safety factor for temperature rising of hydrogen peroxide and the influence of pump efficiency on quality control of motor system simultaneously. It’s very important to know the effect of sealing ring gap at the bottom of impeller on temperature rising of bearing chamber and pump efficiency. So, this paper firstly establishes mathematical modal about the effect of sealing ring gap on temperature rising of bearing chamber and pump efficiency loss, to gain influencing curve, and then it analyzes parameters of cooling flow and mechanism of temperature rising, and give reasonable gap values, which take both safety and efficiency into account. Finally, 3D simulation calculation is carried out through pumplinx to verify the accuracy of this influence model.