Shear bond strength between different materials bonded with two resin cements

doi: 10.1111/j.1741‐2358.2011.00565.x
Shear bond strength between different materials bonded with two resin cements Background: The aim of this study was to compare the shear bond strength between Ni–Cr alloy specimens bonded to air‐abraded Ni–Cr, bur‐abraded Ni–Cr, etched ceramic and etched enamel substrates using the resin cements RelyX ARC or Enforce. Materials and methods: Ni–Cr specimens were made and sandblasted with Al₂O₃ airborne‐particles. Disc‐shaped patterns were made for each of the four experimental substrates: Ni–Cr treated with Al₂O₃ airborne‐particles, Ni–Cr treated with diamond bur abrasion, etched enamel and etched ceramic. Results: Significant differences in shear bond strength were found between the different materials and luting agents evaluated. The Ni–Cr alloy cylinders bonded to Ni–Cr surfaces sandblasted with 50 μm Al₂O₃ particles and bonded with Enforce achieved the highest bond strength when compared with other substrates (28.9 MPa, p < 0.05). Bur‐abraded metal discs had lowest values, regardless the cement used (2.9 and 6.9 MPa for RelyX and Enforce, respectively). Etched enamel and etched ceramic had similar shear bond strengths within cement groups and performed better when RelyX was used. Conclusions: Bonding Ni–Cr to Ni–Cr and ceramic may result in similar and higher bond strength when compared to Ni–Cr/enamel bonding. For metal/metal bonding, higher shear bond strength was achieved with resin cement Enforce, and for metal/ceramic and metal/enamel bonding, RelyX had higher results.     

Shear bond strength between Ni-Cr alloy bonded to a ceramic substrate

doi: 10.1111/j.1741‐2358.2011.00585.x Shear bond strength between Ni‐Cr alloy bonded to a ceramic substrate Introduction: The aim of this study was to evaluate the shear bond strength between a Ni‐Cr alloy and a ceramic system submitted or not to thermocycling. Materials and methods: Forty‐eight cylinder blocks of Ni‐Cr with 3.0 mm diameter by 4.0 mm hight and 48 disc‐shaped specimens (7.0 mm in diameter by 2.0 mm thick) composed of ceramic were prepared. The Ni‐Cr cylinder blocks were randomised in two groups of 24 specimens each. One group was submitted to air‐particle abrasion (sandblasting) with 50 μm Al₂O₃ (0.4–0.7 MPa) during 20 s, and the other group was submitted to mechanical retentions with carbide burrs. Each group was subdivided into other two groups (n = 12), submitted or not to thermocycling (500 cycles, 5–55°C). The cylinder blocks were bonded to the disc‐shaped ceramic specimens under 10 N of load. The shear bond strengths (MPa) were measured using a universal testing machine at a cross head speed of 0.5 mm/min and 200 kgf of load. The data were submitted to statistical analysis (anova and Tukey’s test). Results: The air‐particle abrasion group exhibited significantly higher shear bond strength when compared to drilled group (p < 0.05). Conclusions: Thermocycling decreased significantly the bond strengths for all groups tested.     

Effect of Heat-Pressing Temperature and Holding Time on the Microstructure and Flexural Strength of Lithium Disilicate Glass-Ceramics

The present study aimed to evaluate the influence of various heat-pressing procedures (different holding time and heat pressing temperature) on the microstructure and flexural strength of lithium disilicate glass ceramic. An experimental lithium silicate glass ceramic (ELDC) was prepared from the SiO₂-Li₂O-K₂O-Al₂O₃-ZrO₂-P₂O₅ system and heat-pressed following different procedures by varying temperature and holding time. The flexural strength was tested and microstructure was analyzed. The relationships between the microstructure, mechanical properties and heat-pressing procedures were discussed in-depth. Results verified the feasibility of the application of dental heat-pressing technique in processing the experimental lithium disilicate glass ceramic. Different heat-pressing procedures showed significant influence on microstructure and flexural strength. ELDC heat-pressed at 950℃ with holding time of 15 min achieved an almost pore-free microstructure and the highest flexural strength, which was suitable for dental restorative application.     

Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al₂O₃ ceramic''s EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al₂O₃ ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al₂O₃ ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al₂O₃ ceramic surface shows that the ZnO/Al₂O₃ ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al₂O₃ ceramic.     

Fabrication and biocompatibility of a porous bioglass ceramic in a Na2OCaOSiO2P2O5 system

A porous bioglass ceramic was prepared from a finely pulverized bioglass powder mixed with particles of two sizes (5 and 500 μm) of 30% by weight with the foaming agent polyethylene glycol 4000 (HO (C₂H₄O) nH). The batch composition of the bioglass was Na₂O 12%, CaO 28%, SiO₂ 50% and P₂O₅ 10% by weight. The specimens, formed by pressing, were sintered in a high temperature furnace. In this study we are concerned with the preparation and microstructure of the material and its performance in biological tests. The microstructure and crystalline phases of the material were investigated by differential thermal analysis, X-ray diffraction analysis, transmission electron microscopy and scanning electron microscopy. In a biomedical examination, it was shown that the porous material was compatible with animal tissues. The microstructure of the implant indicated that newly grown bone interlocked well with the glass ceramic and that macropores and micropores were distributed uniformly in the material, which provided channels for bone ingrowth and improved the microscopic bioresorption.     

Interface‐Engineered All‐Solid‐State Li‐Ion Batteries Based on Garnet‐Type Fast Li+ Conductors

All‐solid‐state Li‐ion batteries based on Li₇La₃Zr₂O₁₂ (LLZO) garnet structures require novel electrode assembly strategies to guarantee a proper Li⁺ transfer at the electrode–electrolyte interfaces. Here, first stable cell performances are reported for Li‐garnet, c‐Li_6.25Al_0.25La₃Zr₂O₁₂, all‐solid‐state batteries running safely with a full ceramics setup, exemplified with the anode material Li₄Ti₅O₁₂. Novel strategies to design an enhanced Li⁺ transfer at the electrode–electrolyte interface using an interface‐engineered all‐solid‐state battery cell based on a porous garnet electrolyte interface structure, in which the electrode material is intimately embedded, are presented. The results presented here show for the first time that all‐solid‐state Li‐ion batteries with LLZO electrolytes can be reversibly charge–discharge cycled also in the low potential ranges (≈1.5 V) for combinations with a ceramic anode material. Through a model experiment, the interface between the electrode and electrolyte constituents is systematically modified revealing that the interface engineering helps to improve delivered capacities and cycling properties of the all‐solid‐state Li‐ion batteries based on garnet‐type cubic LLZO structures.     

Development and Performance of MnFeCrO4‐Based Electrodes for Solid Oxide Fuel Cells

Important advances have been made in SOFC development utilizing a ceramic framework based upon yttria zirconia (YSZ) electrolytes supported upon porous YSZ electrode skeletons. This ceramic framework is sintered at high temperatures with subsequent impregnation and low temperature processing of the active electrode materials. Here we seek to develop this impregnated electrode concept by investigating a novel scaffold material similar to the main corrosion product of ferritic stainless steel. The chromium rich spinel (MnFeCrO₄) was used as an electrode support material, either alone or impregnated with (La_0.75Sr_0.25)_0.97Cr_0.5Mn_0.5O_3‐δ, La_0.8Sr_0.2FeO_3‐δ, Ce_0.9Gd_0.1O_2‐δ, CeO₂ and/or Pd. In these initial studies it was found that all of the impregnated phases adhere very well to the spinel and considerably enhance performance and stability to a level sufficient for SOFC applications.     

Thermoluminescent properties of some phosphor glasses based on aluminum oxide

The transparent thermoluminescent aluminum oxide‐based glass of 15Al₂O₃–35P₂O₅–25CaO–25Na₂CO₃, abbreviated as APCN (all in mol%) doped with different concentrations of SiO₂ from 0.0–500 ppm was prepared using a conventional melt‐quenching technique. The TL sensitivities of the prepared glasses were investigated at 3 Gy γ‐dose using a ⁶⁰Co source and measured at a heating rate 10 C/sec. The highest TL intensity of the material doped with SiO₂ was found at a concentration of 500 ppm (APCNSi₅). Deconvolution of the glow curve from APCNSi₅ resulted in four peaks at about 161, 194, 237 and 293 C with a Figure Of Merit (FOM) of 1.28%. The APCNSi₅ specimen had the best dosimetric properties when compared with the other samples. Reproducibility, repeatability, dose–response curve and fading effect were checked for peak 3, which appeared at about 237 C. The results displayed that the APCNSi₅ glass system was a low‐Z material (Z_eff ≈ 10), and had good reproducibility and good repeatability. Peak 3 showed good linearity over a dose range up to 20 Gy (R² = 0.999) and sublinearity behaviour was found. The signal from APCNSi₅ faded by about 11% after 2 days post irradiation, therefore it showed almost no significant loss. Such properties make the newly prepared glasses suitable for and highly recommended for use in γ‐dosimeters. Copyright © 2016 John Wiley & Sons, Ltd.     

New polyoxometalate–laccase integrated system for kraft pulp delignification

New polyoxometalate–laccase integrated system (PLIDS) employing polyoxometalate [SiW₁₁V^VO₄₀]⁵⁻ and laccase of Trametes versicolor for the continuous delignification of eucalypt kraft pulp has been developed. Pulp was delignified in a batch reactor containing catalytic amounts of [SiW₁₁V^VO₄₀]⁵⁻ at about 90 °C under atmospheric pressure. Re-oxidation of reduced polyoxometalate (POM) with laccase was carried out at 45 °C in a separate aerated bioreactor coupled with an ultrafiltration tubular ceramic membrane. This allowed the separation of laccase from re-oxidized POM, which was supplied in turn continuously to the delignification reactor.Proposed PLIDS allowed sustainable pulp delignification with minimal degradation of polysaccharides. The implementation of PLIDS, instead the fist chlorine dioxide stage (D) in conventional DEDED bleaching sequence, showed almost 60% of chlorine dioxide savings with strength properties of the bleached pulp (90% ISO) similar to those obtained after the conventional bleaching.     

Hollow NiCo2S4 Nanospheres Hybridized with 3D Hierarchical Porous rGO/Fe2O3 Composites toward High‐Performance Energy Storage Device

Hierarchical hollow NiCo₂S₄ microspheres with a tunable interior architecture are synthesized by a facile and cost‐effective hydrothermal method, and used as a cathode material. A three‐dimensional (3D) porous reduced graphene oxide/Fe₂O₃ composite (rGO/Fe₂O₃) with precisely controlled particle size and morphology is successfully prepared through a scalable facile approach, with well‐dispersed Fe₂O₃ nanoparticles decorating the surface of rGO sheets. The fixed Fe₂O₃ nanoparticles in graphene efficiently prevent the intermediates during the redox reaction from dissolving into the electrolyte, resulting in long cycle life. KOH activation of the rGO/Fe₂O₃ composite is conducted for the preparation of an activated carbon material–based hybrid to transform into a 3D porous carbon material–based hybrid. An energy storage device consisting of hollow NiCo₂S₄ microspheres as the positive electrode, the 3D porous rGO/Fe₂O₃ composite as the negative electrode, and KOH solution as the electrolyte with a maximum energy density of 61.7 W h kg^?1 is achieved owing to its wide operating voltage range of 0–1.75 V and the designed 3D structure. Moreover, the device exhibits a high power density of 22 kW kg^?1 and a long cycle life with 90% retention after 1000 cycles at the current density of 1 A g^?1.     

Quantifying the impact of current and future tropospheric ozone on tree biomass, growth, physiology and biochemistry: a quantitative meta-analysis

The northern hemisphere temperate and boreal forests currently provide an important carbon sink; however, current tropospheric ozone concentrations ([O₃]) and [O₃] projected for later this century are damaging to trees and have the potential to reduce the carbon sink strength of these forests. This meta‐analysis estimated the magnitude of the impacts of current [O₃] and future [O₃] on the biomass, growth, physiology and biochemistry of trees representative of northern hemisphere forests. Current ambient [O₃] (40 ppb on average) significantly reduced the total biomass of trees by 7% compared with trees grown in charcoal‐filtered (CF) controls, which approximate preindustrial [O₃]. Above‐ and belowground productivity were equally affected by ambient [O₃] in these studies. Elevated [O₃] of 64 ppb reduced total biomass by 11% compared with trees grown at ambient [O₃] while elevated [O₃] of 97 ppb reduced total biomass of trees by 17% compared with CF controls. The root‐to‐shoot ratio was significantly reduced by elevated [O₃] indicating greater sensitivity of root biomass to [O₃]. At elevated [O₃], trees had significant reductions in leaf area, Rubisco content and chlorophyll content which may underlie significant reductions in photosynthetic capacity. Trees also had lower transpiration rates, and were shorter in height and had reduced diameter when grown at elevated [O₃]. Further, at elevated [O₃], gymnosperms were significantly less sensitive than angiosperms. There were too few observations of the interaction of [O₃] with elevated [CO₂] and drought to conclusively project how these climate change factors will alter tree responses to [O₃]. Taken together, these results demonstrate that the carbon‐sink strength of northern hemisphere forests is likely reduced by current [O₃] and will be further reduced in future if [O₃] rises. This implies that a key carbon sink currently offsetting a significant portion of global fossil fuel CO₂ emissions could be diminished or lost in the future.     

SOD1 mutations cause hypersensitivity to high-pressure-induced oxidative stress in Saccharomyces cerevisiae

Living organisms are subject to various mechanical stressors, such as high hydrostatic pressure. Empirical evidence shows that under high pressure, the oxidative stress response is activated in Saccharomyces cerevisiae. However, the mechanisms involved in its antioxidant systems are unclear. Here, we demonstrate that superoxide dismutase 1 (Sod1) plays a role in resisting high pressure for cell growth. Mutants lacking Sod1 or Ccs1, the copper chaperone for Sod1, displayed growth defects under 25 MPa. Of the various SOD1 mutations associated with familial amyotrophic lateral sclerosis, H46Q and S134N substitutions diminished SOD activity to levels comparable to those of catalytically deficient H63A and null mutants. When these mutant cells were cultured under 25 MPa, their intracellular O₂^?– levels increased while sod1? mutant genome stability was unaffected. The high-pressure sensitive sod1 mutants were also susceptible to sublethal levels of the O₂^?– generator paraquat. The sod1? mutant is known to exhibit methionine and lysine auxotrophy. However, excess methionine addition or overexpression of the lysine permease gene LYP1 did not counteract high-pressure sensitivity in the sod1 mutants, suggesting that their amino acid availability might be intact under 25 MPa. Interestingly, an exclusive localization of Sco2-Sod1 to the intermembrane space (IMS) of mitochondria appeared to partially restore the high-pressure growth ability in the sod1 mutants. Taken these results together, we suggest that high pressure enhances O₂^?– production and Sod1 within the IMS plays a role in scavenging O₂^?– allowing the cells to grow under high pressure.BackgroundEmpirical evidence shows that under high hydrostatic pressure, the oxidative stress response is activated in Saccharomyces cerevisiae. However, the mechanisms involved in its antioxidant systems are unclear. In the current study, we aimed to explore the role of superoxide dismutase 1 (Sod1) in yeast able to grow under high pressure.MethodsWild type and sod1 mutant cells were cultured in high-pressure chambers under 25 MPa (~250 kg/cm²). The SOD activity in whole cell extracts and 6His-tagged Sod1 recombinant proteins was analyzed using an SOD assay kit. The O₂^?– generation in cells was estimated by fluorescence staining.ResultsMutants lacking Sod1 or Ccs1, the copper chaperone for Sod1, displayed growth defects under 25 MPa. Of the various SOD1 mutations associated with familial amyotrophic lateral sclerosis, H46Q and S134N substitutions diminished SOD activity to levels comparable to those of catalytically deficient H63A and null mutants. The high-pressure sensitive sod1 mutants were also susceptible to sublethal levels of the O₂^?– generator paraquat. Exclusive localization of Sco2-Sod1 to the intermembrane space (IMS) of mitochondria partially restored the high-pressure growth ability in the sod1 mutants.ConclusionsHigh pressure enhances O₂^?– production and Sod1 within the IMS plays a role in scavenging O₂^?– allowing the cells to grow under high pressure.General significanceUnlike external free radical-generating compounds, high-pressure treatment appeared to increase endogenous O₂^?– levels in yeast cells. Our experimental system offers a unique approach to investigating the physiological responses to mechanical and oxidative stresses in human body.     

Some biophysical principles underlying the controlled atmosphere storage of plant material

Controlled atmosphere (CA) storage is of use for commodities which potentially can undergo rapid and unacceptable biochemical change. In air, the oxygen status of most plant material, including fleshy storage organs and fruits, suffices, even in the centre, for cytochrome oxidase to be fully saturated. Conflict of evidence exists as to possible O₂ and CO₂ gradients in fruit which, though physiologically unimportant in air, could be important under CA conditions. CA storage gives possible control of internal O₂ from o to about 80–95%; internal CO₂ from about 3–4 to 100%; and both simultaneously to intermediate values. Calculated molarities of dissolved O₂, CO₂ and ethylene are given for various atmospheres. The differences in the O₂ concentrations recommended for different varieties of apple are not readily explicable. Varietal differences in susceptibility to CO₂ injury could possibly result from anatomical, rather than biochemical, differences. This could be determined partly by resolving the conflict of evidence mentioned above. Variability of plant material prevents precise control of intercellular atmosphere; recommended atmospheres can be designed only to avoid completely anaerobic conditions and a harmful level of CO₂ in the centre of the least permeable individual fruit or vegetable. Effects of low O₂ and high CO₂ are briefly described.     

Influence of O2 availability on NO and N2O release by nitrification and denitrification in soils

The availability of O₂ is believed to be one of the main factors regulating nitrification and denitrification and the release of NO and N₂O. The availability of O₂ in soil is controlled by the O₂ partial pressure in the gas phase and by the moisture content in the soil. Therefore, we investigated the influence of O₂ partial pressures and soil moisture contents on the NO and N₂O release in a sandy and a loamy silt and differentiated between nitrification and denitrification by selective inhibition of nitrification with 10 Pa acetylene. At 60% whc (maximum water holding capacity) NO and N₂O release by denitrification increased with decreasing O₂ partial pressure and reached a maximum under anoxic conditions. Under anoxic conditions NO and N₂O were only released by denitrification. NO and N₂O release by nitrification also increased with decreasing O₂ partial pressure, but reached a maximum at 0.1–0.5% O₂ and then decreased again. Nitrification was the main source of NO and N₂O at O₂ partial pressures higher than 0.1–0.5% O₂. At lower O₂ partial pressures denitrification was the main source of NO and N₂O. With decreasing O₂ partial pressure N₂O release increased more than NO release, indicating that the N₂O release was more sensitive against O₂ than the NO release. At ambient O₂ partial pressure (20.5% O₂) NO and N₂O release by denitrification increased with increasing soil moisture content. The maximum NO and N₂O release was observed at soil moisture contents of 65–80% whc and 100% whc, respectively. NO and N₂O release by nitrification also increased with increasing soil moisture content with a maximum at 45–55% whc and 90% whc, respectively. Nitrification was the main source of NO and N₂O at soil moisture contents lower than 90% whc and 80% whc, respectively. Higher soil moisture contents favoured NO and N₂O release by denitrification. Soil texture had also an effect on the release of NO and N₂O. The coarse-textured sandy silt released more NO than N₂O compared with the fine-textured loamy silt. At high soil moisture contents (80–100% whc) the fine-textured soil showed a higher N₂O release by denitrification than the coarse-textured soil. We assume that the fine-textured soil became anoxic at a lower soil moisture content than the coarse-textured soil. In conclusion, the effects of O₂ partial pressure, soil moisture and soil texture were consistent with the theory that denitrification increasingly contributes to the release of NO and in particular N₂O when conditions for soil microorganisms become increasingly anoxic.     

Nitrate photo-assimilation in tomato leaves under short-term exposure to elevated carbon dioxide and low oxygen

The role of photorespiration in the foliar assimilation of nitrate (NO₃^–) and carbon dioxide (CO₂) was investigated by measuring net CO₂ assimilation, net oxygen (O₂) evolution, and chlorophyll fluorescence in tomato leaves (Lycopersicon esculentum). The plants were grown under ambient CO₂ with ammonium nitrate (NH₄NO₃) as the nitrogen source, and then exposed to a CO₂ concentration of either 360 or 700 µmol mol^?1, an O₂ concentration of 21 or 2%, and either NO₃^– or NH₄⁺ as the sole nitrogen source. The elevated CO₂ concentration stimulated net CO₂ assimilation under 21% O₂ for both nitrogen treatments, but not under 2% O₂. Under ambient CO₂ and O₂ conditions (i.e. 360 µmol mol^?1 CO₂, 21% O₂), plants that received NO₃^– had 11–13% higher rates of net O₂ evolution and electron transport rate (estimated from chlorophyll fluorescence) than plants that received NH₄⁺. Differences in net O₂ evolution and electron transport rate due to the nitrogen source were not observed at the elevated CO₂ concentration for the 21% O₂ treatment or at either CO₂ level for the 2% O₂ treatment. The assimilatory quotient (AQ) from gas exchange, the ratio of net CO₂ assimilation to net O₂ evolution, indicated more NO₃^– assimilation under ambient CO₂ and O₂ conditions than under the other treatments. When the AQ was derived from gross O₂ evolution rates estimated from chlorophyll fluorescence, no differences could be detected between the nitrogen treatments. The results suggest that short‐term exposure to elevated atmospheric CO₂ decreases NO₃^– assimilation in tomato, and that photorespiration may help to support NO₃^– assimilation.     

Rational Design of Hierarchical “Ceramic‐in‐Polymer” and “Polymer‐in‐Ceramic” Electrolytes for Dendrite‐Free Solid‐State Batteries

Solid polymer electrolytes as one of the promising solid‐state electrolytes have received extensive attention due to their excellent flexibility. However, the issues of lithium (Li) dendrite growth still hinder their practical applications in solid‐state batteries (SSBs). Herein, composite electrolytes from “ceramic‐in‐polymer” (CIP) to “polymer‐in‐ceramic” (PIC) with different sizes of garnet particles are investigated for their effectiveness in dendrite suppression. While the CIP electrolyte with 20 vol% 200 nm Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) particles (CIP‐200 nm) exhibits the highest ionic conductivity of 1.6 × 10^?4 S cm^?1 at 30 °C and excellent flexibility, the PIC electrolyte with 80 vol% 5 µm LLZTO (PIC‐5 µm) shows the highest tensile strength of 12.7 MPa. A sandwich‐type composite electrolyte (SCE) with hierarchical garnet particles (a PIC‐5 µm interlayer sandwiched between two CIP‐200 nm thin layers) is constructed to simultaneously achieve dendrite suppression and excellent interfacial contact with Li metal. The SCE enables highly stable Li plating/stripping cycling for over 400 h at 0.2 mA cm^?2 at 30 °C. The LiFePO₄/SCE/Li cells also demonstrate excellent cycle performance at room temperature. Fabricating sandwich‐type composite electrolytes with hierarchical filler designs can be an effective strategy to achieve dendrite‐free SSBs with high performance and high safety at room temperature.     

Possibility to Apply Strontium Aluminate to Produce Light-Emitting Plants: Efficiency and Safety

Light-emitting plants (LEPs) provides light in areas without electricity. The phosphorescent compound was used as a lighting material for LEP development. However, using the phosphorescent compound for LEPs development required optimization and phytotoxicity evaluation. Strontium aluminate (SrAl₂O₄) is a phosphorescent compound that can glow for a long time and is easily recharged by visible light. In this study, using SrAl₂O₄ to develop LEPs was evaluated. Additionally, plant stress under SrAl₂O₄ was investigated. Metabolomic analysis can explain the possible mechanism of plants’ stress under SrAl₂O₄. After, injecting 3 mL of 5 % (w/v) SrAl₂O₄ products 1, 2, and 3 into the stem of Ipomoea aquatica, the result showed that SrAl₂O₄ products 2 and 3 caused oxidative stress. The metabolomic analysis also indicated that I. aquatica responded to SrAl₂O₄ product 1 by increasing pipecolic acid and salicylic acid, while I. aquatica injected with SrAl₂O₄ products 2 and 3 showed a decrease in salicylic acid around 0.005 and 0.061-fold, respectively, compared to control plants. and an excess accumulation of MDA around 10.00–12.00 μmol g⁻¹ FW. A 15 % concentration of SrAl₂O₄ can be used for LEPs development, enabling photoemission 18-fold for 50 min. SrAl₂O₄ product 1 has the potential to be a material for LEPs.     

Extent estimates and land cover relationships for functional indicators in non-wadeable rivers

Functional indicators are being increasingly used to assess waterway health but their responses to pressure in non-wadeable rivers have not been widely documented or applied in modern survey designs that provide unbiased estimates of extent. This study tests the response of river metabolism and loss in cotton strip tensile strength across a land use pressure gradient in non-wadeable rivers of northern New Zealand, and reports extent estimates for river metabolism and decomposition rates. Following adjustment for probability of selection, ecosystem respiration (ER) and gross primary production (GPP) for the target population of order 5–7 non-wadeable rivers averaged −7.3 and 4.8 g O₂ m⁻² d⁻¹, respectively, with average P/R < 1 indicating dominance by heterotrophic processes. Ecosystem respiration was <−3.3 g O₂ m⁻² d⁻¹ for 75% of non-wadeable river length with around 20% of length between −10 and −20 g O₂ m⁻² d⁻¹. Cumulative distribution functions of cotton strength loss estimates indicated a more-or-less linear relationship with river km reflecting an even spread of decay rates (range in k 0.0007–0.2875 d⁻¹) across non-wadeable rivers regionally. A non-linear relationship with land cover was detected for GPP which was typically <5 g O₂ m⁻² d⁻¹ where natural vegetation cover was below 20% and greater than 80% of upstream catchment area. For cotton strength loss, the relationship with land cover was wedge-shaped such that sites with >60% natural cover had low decay rates (<0.02 d⁻¹) with variability below this increasing as natural cover declined. Using published criteria for assessing waterway health based on ER and GPP, 232–298 km (20–29%) of non-wadeable river length was considered to have severely impaired ecosystem functioning, and 436–530 km (42–50%) had no evidence of impact on river metabolism.     

The effect of excision on O2 diffusion and metabolism in soybean nodules

Nitrogen-fixing nodules of soybean [Glycine max (L.) Merr. cv. Maple Arrow inoculated with Bradyrhizobium japonicum USDA 16] were studied before and after excision from the root to determine the role the O₂ regulation plays in the inhibition of nodule activity and the potential for using excised nodules nodules in studies of nodule metabolism. Relative nitrogenase (EC 1.7.99.2) activity (H₂ evolution in N₂:O₂) and nodule respiration (CO₂ evolution) were monitored first in intact nodulated roots and then in freshly excised nodules of the same plant to determine the time course of the decline in nodule metabolism. Folowing excision, nitrogenase activity and respiration declined rapidly in the first minute and then more gradually. After 40 min the rate of H₂ evolution was only 14–28% of that in the intact plant. In some nodules activity declined steadily, and in others there was a partial recovery in activity ca 10 min after detachment. Infected cell O₂ concentration (O_i), measured by a spectro-photometric technique, also declined after nodule detachment with a time course similar to the declines in nitrogenase activity and respiration. Following excision, O_i levels declined rapidly from ca 21 nM in attached nodules to 8–12 nM at 4–10 min after excision and then more gradually to 2–3 nM O₂ at 30–40 min after excision. These results show that the nodules' permeability to gas diffusion continued to be regulated for up to 40 min after detachement. At 40 min after detachment, when excised nodules displayed steady-state rates of gas exchange, linear increases in pO₂ from 20 to 100% at 4% min^?1 resulted in recoveries of H² and CO² evolution, indicating that O_i limited nitrogenase activity durig this period, and that energy reserves were greatly in excess of the O₂ available for respiration. When detached nodules were equilibrated for 12 h at 20, 30 and 50% O₂, O_i values measured at supra-ambient pO₂ were greater than those at 20% O₂ and were linked with a more rapid decline in nitrogenase activity. Also, increases in external pO₂ (O_c) failed to stimulate nodule metabolism, suggesting that the nodules' energy reserves were no longer greatly in excess of their respiratory demands. It was concluded that soybean nodules could provide useful material for steady-state studies of nodule metabolism between 40 and 240 min after detachment, but to attain metabolic rates equivalent to in vivo rates the nodules must be exposed to above-ambient pO₂.     

Colorimetric detection of gallic acid based on the enhanced oxidase‐like activity of floral‐like magnetic Fe3O4@MnO2

In this study, a colorimetric method was developed for rapid and sensitive determination of gallic acid (GA) by using floral‐like magnetic Fe₃O₄@MnO₂ composite material with enhanced oxidase‐like activity. Fe₃O₄@MnO₂ composite material is able to oxidize 3,3′,5,5′‐tetramethylbenzidine (TMB) to a blue product (oxTMB) with apparent color change and absorbance at 652 nm. GA can reduce the oxTMB yielding a fading blue color. Based on these results, a technique is proposed to detect GA quantitatively and qualitatively with UV–vis spectroscopy and bare eyes. A low detection limit of 0.105 μM and a detection range of 0.01 to 15 μM were obtained with UV–vis spectroscopy. This methodology possesses high potential for application in determination of GA.