High Oxidizability Research Articles

A colorimetric immunosensor based on self-linkable dual-nanozyme for ultrasensitive bladder cancer diagnosis and prognosis monitoring

We developed self-linkable Prussian blue (PB)-incorporated magnetic graphene oxide (PMGO) as a peroxidase-mimicking nanozyme with high oxidizability to 3,3′,5,5′-tetramethylbenzidine (TMB), which generates significant absorption intensity for the colorimetric immunosensing of apolipoprotein A1 (ApoA1) in early bladder cancer (BC) diagnosis and prognosis monitoring. The ultrasensitive immunosensor was constructed using an ApoA1 antibody (AbApoA1)-functionalized chip (biochipApoA1) and self-linkable peroxidase-mimicking, PB-incorporated magnetic graphene oxide (PMGO). After incubating the sample and capturing ApoA1 proteins captured on the biochipApoA1, the PMGO was functionalized with AbApoA1, and then mouse IgG (PMGO-1), rabbit anti-mouse IgG antibody (PMGO-2), and goat anti-rabbit IgG antibody (PMGO-3) were added together. We envisioned that each captured ApoA1 protein would allow the retention of a large amount of PMGO through a self-linking process to amplify the colorimetric signal of TMB in the presence of H2O2. The linear detection range could be obviously widened in the presence of self-linkable PMGO—from 0.05 ng/mL to 100 ng/mL—compared with the group without signal amplification (from 1 ng/mL to 100 ng/mL). Our immunosensor analysis of ApoA1 in the urine of BC patients and healthy individuals was highly correlated with enzyme-linked immunosorbent assay measurements; moreover, the ApoA1 concentrations of patients with high-grade BC were significantly higher than those of patients with low-grade BC. After standard clinical treatment, a significant drop of ApoA1 concentration occurred in urine that was lower than the cut-off concentration, suggesting potential clinical applications of the new self-linkable PMGO-generating colorimetric immunosensor in early BC diagnosis and prognosis monitoring.

Rational construction of direct Z-scheme LaMnO3/g-C3N4 hybrid for improved visible-light photocatalytic tetracycline degradation

Semiconductor driven photocatalysis has been demonstrated to be one of the promising and effective approaches to resolve the increasing energy and environmental crises by utilizing solar energy. As a typical metal-free semiconductor photocatalyst, graphitic carbon nitride (g-C3N4) has attracted tremendous attention in the photocatalytic water splitting, CO2 reduction and organic pollutants degradation. Unfortunately, the rapid recombination of photoinduced electron-hole pairs of g-C3N4 severely restrained its photocatalytic performance. To this end, lanthanum manganate (LaMnO3) was used to interact with g-C3N4 to rationally construct a direct Z-scheme LaMnO3/g-C3N4 hybrid as an efficient visible-light-driven photocatalyst for the photocatalytic degradation of tetracycline (TC). As expected, the LaMnO3/g-C3N4 product exhibited significant improvement on the performance of photocatalytic TC degradation in aqueous solution under visible light irradiation (λ > 420 nm). Especially, the optimized LaMnO3(9.8 wt%)/g-C3N4 hybrid with 9.8 wt% LaMnO3 achieved the highest apparent first-order rate constant, which was around 10.6 times larger than that of pristine g-C3N4 and 4.0 times greater than that of single LaMnO3. Such an enhanced photocatalytic activity could be ascribed to the formation of unique Z-scheme LaMnO3/g-C3N4 feature, which not just efficiently promoted the separation of the photoinduced electron-hole pairs, but also maintained the strong reducibility of electrons in the conduction band of g-C3N4 and high oxidizability of holes in the valence band of LaMnO3. Furthermore, a probable degradation mechanism was tentatively proposed based on the results of energy band structures, active species trapping experiments, photoluminescence spectroscopy and photoelectrochemical measurements. This work creates a new opportunity for the rational design and construction of highly efficient and stable g-C3N4-based Z-scheme hybrid photocatalysts for applying in environmental remediation and energy conversion.

Nanosized cationic and anionic manganese porphyrins as mesoporous catalysts for the oxidation of olefins: Nano versus bulk aggregates

In this study, catalytic activity of bulk and nano‐sized meso‐tetrakis(4‐sulfonatophenyl)porphyrinatomanganese(III) acetate, MnTPPS4(OAc), (ammonium salt) and meso‐tetrakis(3‐methylpyridyl)porphyrinatomanganese(III) acetate, MnT(3‐MePy)P(OAc) (tosylate salt) for the oxidation of olefins with tetra‐n‐butylammonium Oxone has been studied and compared with that of the bulk counterparts. The nanoparticles were prepared by mixing solvent techniques using water, (triethyleneglycol) monomethyl ether and dimethylsulfoxide or acetonitrile. The formation of nano‐sized catalysts was confirmed by UV‐Vis spectroscopy, DLS and AFM. Nitrogen porosimetry measurements indicated the homogeneous pore size distribution in the bulk and nano‐sized manganese porphyrins. In spite of the high oxidizability of Oxone, the heterogenized manganese porphyrins showed a significantly higher oxidative stability relative to their homogeneous counterparts within a reaction time of 6 h. The increase in the catalytic activity induced by the formation of nano‐sized catalysts was more pronounced in the case of MnT(3‐MePy)P(OAc). MnT(3‐MePy)P(OAc) may be recovered and reused for at least 4 times without any significant decrease in the catalyst efficiency. In the case of MnTPPS4(OAc) a large decrease in the catalytic activity was observed after the first use of the catalyst. The latter was attributed to higher degrees of catalyst degradation in the case of MnTPPS4(OAc).

A novel colorimetric strategy for sensitive and rapid sensing of ascorbic acid using cobalt oxyhydroxide nanoflakes and 3,3′,5,5′-tetramethylbenzidine

In this work, cobalt oxyhydroxide nanoflakes (CoOOH nanoflakes) were reported to possess a high oxidizability toward TMB for the first time and based on which we have developed a new strategy for qualitative and quantitative detection of ascorbic acid (AA). In our design, CoOOH nanoflakes can directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to oxTMB with an obvious blue color emerging, and AA can selectively inhibit the oxidation of TMB to oxTMB by resolving CoOOH nanoflakes to Co2+, resulting in a decrease in the absorbance of oxTMB and bleaching of blue color. As such, the concentration of AA could be identified very easily by UV–vis spectroscopy and bare eyes. Under optimal conditions, this sensing platform showed a highly sensitive response to AA with a detection limit of 142nM and a short assay time of 5min. This assay was also successfully used to quantify AA in human serum samples and practical food samples. Importantly, using this fabricated sensing strategy, we have further developed a paper-based strip sensor for AA detection with satisfactory results, showing its great potential for point of care applications.

Oxidizing, trapping and releasing NOx over model manganese oxides in alternative lean-burn/fuel-rich atmospheres at low temperatures

Herein, we report the performance of the catalytic oxidizing, trapping and releasing NO over the MnOx (Mn2O3, Mn3O4 and MnO2) model Lean NOx Traps (LNT) catalysts at low temperatures (≤200°C). Among these typical MnOx samples, Mn2O3 has the high NO oxidizability, and can efficiently trap and release NOx in the alternative lean-burn/fuel-rich atmospheres. Our characterization results show that enrichment of the Mn3+ cations and active surface oxygen species probably plays the important role for NO oxidation. Although MnO2 has the biggest NOx storage capacity in the lean-burn atmosphere, the strong adsorption strength between MnO2 and NOx inhibits the release of the stored NOx species in the fuel-rich atmosphere. The in situ DRIFTS and NO-TPD studies indicate that the trapped NOx on Mn2O3 can transform from nitro compounds to nitrites, and then to nitrates along with the increased adsorption temperature.

Reagent removal of manganese from ground water

The study is aimed at the technology development of treating drinking water from ground waters with high manganese content and oxidizability. Current technologies, physical/chemical mechanisms and factors affecting in ground treatment efficiency are reviewed. Research has been conducted on manganese compound removal from ground waters with high manganese content (5 ppm) and oxidizability. The studies were carried out on granular sorbent industrial ODM-2F filters (0.7–1.5 mm fraction). It was determined that conventional reagent oxidization technologies followed by filtration do not allow us to obtain the manganese content below 0.1 ppm when treating ground waters with high oxidizability. The innovative oxidation-based manganese removal technology with continuous introduction of reaction catalytic agent is suggested. This technology is effective in alkalization up to pH 8.8–9. Potassium permanganate was used as a catalytic agent, sodium hypochlorite was an oxidizer and cauistic soda served an alkalifying agent.

Improving sunlight-driven photocatalytic activity of ZnO nanostructures upon decoration with Fe(III) cocatalyst

In the study, the Fe(III) cocatalysts were grafted successfully on the surface of ZnO nanostructures to form Fe(III)/ZnO photocatalysts by a simple impregnation technique. It was found that the morphologies and crystal structures of ZnO remain unchanged after modification of the Fe(III) clusters. And the photocatalytic activity and the stability for the degradation of Rhodamine B were also evaluated. Under simulated sunlight illumination for 210min, an almost complete degradation was achieved over Fe(III)/ZnO nanocomposites. The mechanism of the enhancement is associated with a direct interfacial charge transfer process (IFCT). The Fe(III) clusters not only acted as electron sinks to enhance the separation of photoinduced electrons from holes, but also elevated the amount of the holes, leading to the production of more hydroxyl radical with high oxidizability.

Wear Characteristics of Mo-W-Type Hot-Work Steel at High Temperature

The friction and wear characteristics of new Mo-W-type hot-work die steel, known as SDCM-S, were studied at high temperature. The results showed that the new Mo-W-type steel had greater wear resistance compared with H13 steel, which was due to its high oxidizability and high-temperature property. The high oxidizability and high temper stability features facilitate the generation, growth, and maintenance of a tribo-oxide layer at high temperature under relatively stable conditions. The thick tribo-oxide layer and high temper stability postpone the transition from mild to severe wear and ensure that conditions of mild oxidative wear are maintained in SDCM-S steel. The M2C and M6C carbides in Mo-W-type steel increase the temper stability and provide sufficient additional support for the formation and growth of a single thick tribo-oxide layer at high temperature. Mild oxidative wear is the dominant wear mechanism for SDCM-S steel between 400 and 700 °C.

Wear Resistance of H13 and a New Hot-Work Die Steel at High temperature

The friction and wear behaviors of a new hot-work die steel, SDCM-SS, were studied at high temperature under dry air conditions. The wear mechanism and microstructural characteristics of the SDCM-SS steel were also investigated. The results showed that the SDCM-SS steel had greater wear resistance compared with H13 steel; this was owed to its high oxidizability and temper stability. These features facilitate the generation, growth, and maintenance of a tribo-oxide layer at high temperature under relatively stable conditions. The high oxidizability and thermal stability of the SDCM-SS steel originate from its particular alloy design. No chromium is added to the steel; this ensures that the material has high oxidizability, and facilitates the generation of tribo-oxides during the sliding process. Molybdenum, tungsten, and vanadium additions promote the high temper resistance and stability of the steel. Many fine Mo2C and VC carbides precipitate during the tempering of SDCM-SS steel. During sliding, these carbides can delay the recovery process and postpone martensitic softening. The high temper stability postpones the transition from mild to severe wear and ensures that conditions of mild oxidative wear are maintained. Mild oxidative wear is the dominant wear mechanism for SDCM-SS steel between 400 and 700 °C.

Применение коагулянтов в процессе обезжелезивания и обескремнивания подземных вод

Results of treatment of groundwater with the increased content of iron, silicon and high permanganate oxidizability are presented. A novel technique of deferrization and desiliconization on the basis of the coagulation and oxidation processes is proposed. In the process water is to be treated simultaneously with a coagulant (aluminum polyoxychloride) and an oxidizer (potassium permanganate) then it is to be filtered on a grained bed. It has been stated that the optimal Al/KMnO4 proportion is to be equal to 10. Concurrent processing with a coagulant and an oxidizer enables to dispose effectively iron with organic matter. The proposed technique can be recommended for simultaneous deferrization and desiliconization of groundwater with permanganate oxidizability exceeding 5 mgO2/l.

Recent evidence on omega 6 fatty acids and cardiovascular risk

As evidence accumulates, our knowledge of the role of individual fatty acids in cardiovascular disease improves. This re‐evaluation is being applied to poly‐ (PUFAs) and mono‐ (MUFAs) unsaturated fatty acids. Among the former, omega 6 (or n‐6) fatty acids from vegetables and seed oils have always been labeled as cardioprotective. However, this notion was challenged in the 80s, when in vitro data on the high oxidizability of omega 6 fatty acids, their potential pro‐inflammatory effects purportedly due to the formation of prostaglandins, and their hypothesized competition for the same enzymes that elongate and desaturate omega 3 fatty acids cast doubts on their healthful roles and even led to the suggestion to limit their dietary intake. As outlined in this review and based on the most recent studies, this is most probably not the case: indeed, adequate intakes of omega 6 fatty acids appear to be extremely helpful in CHD risk reduction and a hypothetical reduction of omega 6 intake by the population at large would actually increase CHD risk.Main biological effects of omega 6 fatty acids.

Altered lipid subfraction profile and impaired antioxidant defense of high-density lipoprotein in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a rare disease caused by biallelic mutation in the 7-dehydrocholesterol (7DHC) reductase gene. High oxidizability of 7DHC and the appearance of small-sized low-density lipoprotein (LDL) subfractions indicate increased endogenous oxidative stress that is counterbalanced by natural antioxidant defense mechanisms including the high-density lipoprotein (HDL)-associated paraoxonase-1 (PON1) enzyme. PON1 prevents lipoproteins from oxidative modifications; however, PON1 activity and the distribution of lipoprotein subfractions have not been studied in SLOS. 7DHC levels and PON1 arylesterase activities were measured spectrophotometrically in 11 SLOS patients and 10 healthy children. Lipoprotein subfractions were detected by polyacrylamide gel electrophoresis. Compared to controls, there was a shift towards the small-dense LDL subfraction and the large HDL subfraction in SLOS. PON1 arylesterase activity was significantly decreased in SLOS patients and correlated negatively with the proportion of small-dense LDL subfraction and the proportion of large HDL subfraction. Significant positive correlations were detected between PON1 arylesterase activity and the ratios of intermediate and small HDL subfractions. Decreased PON1 activity and the deleterious shift in the distribution of lipoprotein subfractions may contribute to the impaired antioxidant status observed in SLOS. Monitoring of serum PON1 arylesterase activity may be a complementary biomarker in SLOS.

Reducing the driving voltage of organic light-emitting diodes by inserting a transparent ultrathin layer of oxidized silver as a hole-injecting layer

Organic light-emitting diodes (OLEDs) containing a transparent ultrathin layer of oxidized silver as a hole-injecting layer, placed between a indium–tin-oxide (ITO) electrode and the hole-transporting layer, were fabricated, and their electrical and luminescent properties were investigated. The OLEDs had a structure that consisted of an ITO layer; followed by an ultrathin Ag layer oxidized by a ultraviolet (UV)–ozone surface treatment; a N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD) layer; a 5,6,11,12-tetraphenylnaphthacene (rubrene)-doped 9,10-diphenylanthracene (DPA) layer; a tris-(8-hydroxyquinoline) aluminum (Alq3) layer; a lithium fluoride (LiF) layer; and a Al layer. The operating voltages of the OLEDs with the oxidized Ag (i.e., AgOx) layer were drastically lower than those of the layer-free OLEDs, because the AgOx layer, which had high oxidizability, contributed to hole injection as it oxidized the surface of the α-NPD layer. However, the external quantum efficiency of the OLEDs with the AgOx layer was lower than that of the AgOx layer-free OLEDs, suggesting that the carrier balance (i.e., the balance between the holes and electrons) became uneven in the emission layer, owing to the insertion of the AgOx layer. It was assumed that this imbalance resulted from the number of holes in the emission layer being higher because of the increase in hole injection in the AgOx layer.

Altered distribution of lipid subfractions and decreased paraoxonase-1 activity in children with smith-lemli-opitz syndrome

Objectives: Smith-Lemli-Opitz syndrome (SLOS) is a rare inherited disease caused by the gene mutation of 7-dehydrocholesterol (7DHC) reductase catalyzing the last step of cholesterol biosynthesis. High oxidizability of 7DHC and the appearance of small-sized low-density lipoprotein (LDL) subfractions may indicate an increased endogenous oxidative stress. In turn, high-density lipoprotein (HDL)-linked paraoxonase-1 (PON1) enzyme prevents lipoproteins from oxidative modifications. Our aim was to determine PON1 activity and the distribution of lipoprotein subfractions in SLOS.

Efficient aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran on manganese oxide catalysts

A cryptomelane-type manganese oxide octahedral molecular sieve with a (2×2, 4.6Å×4.6Å) tunnel size (OMS-2) efficiently catalyzed aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with a high yield of 97.2% at 383K and 0.5MPa O2 in N,N-dimethylformamide. OMS-2 was superior to other MnO2 catalysts with different morphologies, including OMS-1, OMS-6, and OMS-7 with various tunnel sizes, amorphous MnO2 and birnessite-type MnO2, apparently due to its (2×2) tunnel structure and consequently high reducibility and oxidizability. Kinetic and isotopic studies on OMS-2 showed near half-order dependence of the activities on HMF and O2 concentrations and marked kinetic isotope effects for deuterated HMF at its methylene group. These results, together with the similar initial rates under aerobic and anaerobic conditions, suggest that HMF oxidation to DFF on OMS-2 proceeds via a redox mechanism involving kinetically-relevant steps of C–H bond cleavage in adsorbed alcoholate intermediate, derived from quasi-equilibrated dissociation of HMF, using lattice oxygen and reoxidation of Mn3+ to Mn4+ by dissociative chemisorption of O2.

Preparation of platinum nanoparticles on TiO2 from DNA-protected particles

This paper reports on preparation methods for TiO2-supported Pt catalysts (Pt/TiO2) using colloidal DNA-protected Pt particles. Pt nanoparticles with the average size of 1.4nm were prepared by reduction of H2PtCl6 with NaBH4 in aqueous solution in the presence of salmon sperm deoxyribonucleic acid (DNA). The Pt particles were deposited on TiO2 with high dispersion by mixing the TiO2 powder with the Pt particles in the solution. The DNA polymer was completely removed from the Pt/TiO2 surface by centrifugation and washing processes. XAFS studies revealed that the DNA-stabilized Pt particles mainly consisted of Pt oxides. The Pt dispersion on TiO2 did not depend on the amount of DNA in colloidal Pt dispersion, whereas the Pt loading level increased with the increase in the DNA amount. The Pt/TiO2 catalysts after oxidation–reduction treatment have both high oxidizability and reducibility, and the catalysts exhibited higher activity for CO oxidation than the PtTiO2 catalyst prepared by impregnation technique.

Research on Using Limestone for Slagging during BOF Steelmaking Process

This paper introduced the primary research on the method of using limestone instead of lime for slagging during BOF steelmaking. The study showed that the heat is sufficient for limestone to completely replace lime on the condition that the ratio of hot metal to ferrous scrap is adjusted properly. According to thermodynamic calculations, the partial pressure of CO2at the hot metal surface at the early stage of converter steelmaking is close to 0 and nearly all the CO2can react with elements in hot metal, producing CO and reducing O2consumption. Slag with high oxidizability, high basicity and relatively low temperature can be formed quickly by using limestone, which is advantageous for dephosphorization. Industrial tests showed the endpoint Lp rises with the proportion of lime replaced by limestone increasing. CO2volume expands by 4000~30000 times when limestone is heated at extremely high speed in converter, resulting in the fragmentation of some parts of limestone and the increase of the contacting area of limestone and slag. The unreacted core model with surface exfoliated was introduced.

Lipid biomarkers of oxidative stress in a genetic mouse model of Smith‐Lemli‐Opitz syndrome

7-Dehydrocholesterol (7-DHC) accumulates in tissues and fluids of patients with Smith-Lemli-Opitz syndrome (SLOS), which is caused by mutations in the gene encoding 3β-hydroxysterol-Δ(7)-reductase (DHCR7). We recently reported that 7-DHC is the most reactive lipid molecule toward free radical oxidation (lipid peroxidation) and 14 oxysterols have been identified as products of oxidation of 7-DHC in solution. As the high oxidizability of 7-DHC may lead to systemic oxidative stress in SLOS patients, we report here lipid biomarkers of oxidative stress in a Dhcr7-KO mouse model of SLOS, including oxysterols, isoprostanes (IsoPs), and neuroprostanes (NeuroPs) that are formed from the oxidation of 7-DHC, arachidonic acid and docosahexaenoic acid, respectively. In addition to a previously described oxysterol, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), we provide evidence for the chemical structures of three new oxysterols in the brain and/or liver tissue of Dhcr7-KO mice, two of which were quantified. We find that levels of IsoPs and NeuroPs are also elevated in brain and/or liver tissues of Dhcr7-KO mice relative to matching WT mice. While IsoPs and NeuroPs have been established as a reliable measurement of lipid peroxidation and oxidative stress in vivo, we show that in this genetic SLOS mouse model, 7-DHC-derived oxysterols are present at much higher levels than IsoPs and NeuroPs and thus are better markers of lipid oxidation and related oxidative stress.

Viscosity Determination of High Oxidizability Refining Slag and Its Buildup Solution

The principal purpose of this paper are to determine the viscosity of refining slag with the features of high crystallinity and strongly oxidizability, and to solve the problem that slag sticked onto the RH immersion tube during the RH refining process. Then, the fluid length method was used to determine the viscosity, and the effect of compositions on melting point and viscosity of refining ladle slag was studied. Overall, the relationship between viscosity and fluid length was acquired, and it achieved the slag with lower melting point and good fluidity which can avoid slag building-up on RH immersion tube by adjusting the basicity of refining slag to 4-5, the content of Al2O3 to 14-15% with additives.

Experience gained from putting new technologies of water treatment in use at thermal power stations

The results obtained from laboratory studies and in the course of industrial tests of water treatment technologies used in new water treatment plants operating on low-mineralized water with high oxidizability (characterized by the permanganate oxidizability Ox = 15–25 mg O/dm3) are described. Data obtained from operational examination of a weak-base anion-exchange resin carried out after the plant had produced 150000 m3 of demineralized water are presented.