Oxygen Source Research Articles

Visible-Light-Induced Desaturative β-Alkoxyoxalylation of N-Aryl Cyclic Amines with Difluoromethyl Bromides and H2O Via a Triple Cleavage Process.

A visible-light-driven desaturative β-alkoxyoxalyation of N-aryl cyclic amines with difluoromethyl bromides and H2O has been reported. This tandem reaction is triggered by homolysis of the C-Br bond to produce the difuoroalkyl radical, which undergoes the subsequent defluorinated β-alkoxyoxalylation cascades to afford a wide range of β-ketoester/ketoamides substituted enamines. The prominent feature of this reaction contains photocatalyst-free, transition-metal free, and mild conditions. The 18O labeling experiment disclosed that H2O is the oxygen source of the carbonyl unit.

Development of Fuel Cell System Using Metal Hydride and Hydrogen Peroxide in Low-Oxygen Environments

Hydrogen energy is attracting attention as a promising power system due to high energy storage density and environmentally friendly features. For these reasons, fuel cell system using hydrogen energy in unmanned underwater vehicles have been studied. However, in low-oxygen environment, fuel cell system requires an oxygen storage as well as a hydrogen storage. In this study, a fuel cell system using a metal hydride and hydrogen peroxide was designed. The metal hydride can charge and discharge hydrogen at a lower pressure than a high-pressure hydrogen tank and has a high hydrogen storage density. In this system, AB2 type metal hydride is used to store hydrogen. Hydrogen desorption reaction of the metal hydride is an endothermic reaction, and heat supply is required to maintain the temperature of the metal hydride in order to stably supply hydrogen. Therefore, in this system, hydrogen peroxide was used as an oxygen source. Hydrogen peroxide reacts with a metal catalyst to generate oxygen and water. The decomposition reaction of hydrogen peroxide is an exothermic reaction and can supply heat required for the metal hydride. In this system, hydrogen peroxide is decomposed into water and oxygen through a catalytic reaction, and the generated heat is supplied to the metal hydride. Finally, hydrogen and oxygen are supplied to the PEMFC stack to generate power. For system design, in this study, PCT characteristics of AB2 type metal hydride, thermal management method, and hydrogen peroxide decomposition catalyst were studied, and an operation strategy for non-humidified PEMFC operation was proposed. This system generated a power output of about 290 W for 97 hours, and the hydrogen utilization rate of the fuel cell was confirmed to be 92.3%.

Graphene Quantum Dots as an Oxygen Reservoir for Topotactic Phase Transition‐Based Memristive Devices

AbstractA novel class of transition metal oxides, capable of reversible topotactic phase transition between the oxygen‐deficient brownmillerite and oxygen‐rich perovskite, has emerged as a promising material for memristive and magnetoelectric devices. However, the absence of a local oxygen source in the device structure necessitates an oxygen exchange process between the surrounding atmosphere and the switching layer during operation, which can lead to unreliable device performance. In this study, graphene quantum dots (GQDs) are introduced into a SrFe0.5Co0.5Ox memristive device as an oxygen reservoir for the nanoscale topotactic redox process. The SrFe0.5Co0.5Ox memristive devices with GQDs exhibit reliable resistive switching performance compared to SrFe0.5Co0.5Ox devices without GQDs. To understand the effect of GQDs on the device structure, a pulse endurance test is carried out in a high vacuum. The devices with GQDs show rather good endurance behavior, while devices without GQDs exhibit endurance failure. These results provide a deeper understanding of the potential use of GQDs in enhancing the performance of SrFe0.5Co0.5Ox memristive devices, with implications for tuning nanoscale topotactic phase transition for multi‐functional properties.

The Surface Behavior of ZnO Films Prepared at Room Temperature

The surface behavior of ZnO-based films can be modulated via the postannealing and ultraviolet (UV) illumination of different strengths and durations, respectively. The present results could provide the basis for modulating their microstructures with respect to the grain-size distribution and photocatalytic behavior, and act as a potential guide in the field of wide-bandgap semiconducting oxides. ZnO films were prepared at room temperature onto Corning-1737 glass substrates by applying radio-frequency magnetron sputtering without supplying an oxygen source. With the purpose of obtaining modulational grain microstructures, the as-prepared ZnO films (Z0) were treated via a postannealing modification in a vacuum furnace at 300 °C for 30 min after deposition (Z300), accompanied by adjustable internal stress. The contact angle (CA) value of the ZnO films was reduced from 95° to 68°, owing to the different grain microstructure accompanied by a change in the size variation. In addition, UV light with different illumination strengths could be used to improve the hydrophilicity, which varied from a hydrophobic status to a superhydrophilic status due to the desirable surface characteristics of its photocatalytic action. In addition, the photocatalytic activity of the ZnO films exhibited an effectual photodegradation of methylene blue (MB) under UV illumination, with a chemical reaction constant of 2.93 × 10−3 min−1. In this present work, we demonstrated that the CA value of the ZnO films not only caused a change from a hydrophobic to hydrophilic status, accompanied by a change in grain size combined with internal stress, but also, induced by the UV light illumination, was combined with photocatalytic activity simultaneously. On the other hand, an enhanced surface plasmonic resonance was observed, which was due to couple oscillations between the electrons and photons and was generated from the interface by using a flat, continuous Pt capping nanolayer. This designed structure may also be considered as a Pt electrode pattern onto ZnO (metal Pt/ceramic ZnO) for multifunctional, heterostructured sensors and devices in the near future.

Suppression of nitrite oxidizing bacteria by hydrogen peroxide for energy reduction in municipal wastewater treatment

This paper investigated the application of hydrogen peroxide (H2O2) for achieving partial nitrification in mainstream municipal wastewater treatment process. The investigation was carried out in both bench-scale and pilot-scale sequencing batch reactor systems using primary effluent as feed from municipal wastewater treatment plant. H2O2 played a dual role of: (1) inhibitor for nitrifying microorganisms, and (2) supplemental oxygen source. Bench scale studies were carried out at various doses of initial hydrogen peroxide concentrations (10,25,50,100 mg/L). It was found that at a concentration of 50 mg/L and above ammonia removal reduced by more than 80% implying significant impact on both ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). After an acclimatization period of 18 days at a dose of 50 mg/L H2O2, complete nitrification was observed with about 30% nitrite accumulation in the effluent which showed NOBs were impacted more significantly than AOBs. It was also observed from the long-term pilot-scale study that the inhibitory impact on NOBs is almost double the impact of on AOBs which facilitated partial nitrification resulting a nitrite accumulation ratio up to 60% in the effluent at 2 mg/L DO and 15 days SRT.Peroxide dosing resulted in an energy savings of 12–15% compared to a control reactor. It was also shown that by reducing the DO from 2 to 1 mg/L, additional power saving of 15% is achievable. Therefore, the proposed approach is an efficient method for aeration energy savings and can be easily implemented in existing wastewater treatment plants.

Effects of the oxygen source configuration on the superconducting properties of internally-oxidized internal-Sn Nb3Sn wires

We successfully manufactured 12-filament rod-in-tube Nb3Sn wires with oxide nanoparticles formed by the internal oxidation method. We employed Nb-7.5 wt%Ta-1 wt%Zr and Nb-7.5 wt%Ta-2 wt% Hf alloys along with oxygen sources (OSs) in two different configurations—in the core of Nb filaments (coreOS) and at the boundary between the filaments and the Cu tube (annularOS)—to assess the influence of the OS layout on the superconducting properties and grain size. The simultaneous presence of the OS and of Hf or Zr reduced the average Nb3Sn grain size to around 50 nm, leading to an enhancement of the layer critical current density (Jc ) up to 3000 A mm−2 at 4.2 K and 16 T for the Hf-annularOS wire. Samples manufactured with an OS show a shift toward higher reduced magnetic fields of the position of the maximum in pinning-force density, this shift being more pronounced when SnO2 is added in the annularOS configuration, and for the Hf-containing samples. This enhanced pinning at higher magnetic field is beneficial for high-field magnet applications. Moreover, we measured a very high upper critical field, reaching 29.3 T at 4.2 K in the Hf-annularOS samples.

Dynamics of oxygen sources and sinks in the Baltic Sea under different nutrient inputs

The Baltic Sea is one of the marine systems suffering from pronounced man-made hypoxia due to the elevated nutrient loads from land. To mitigate hypoxia expansion and to return the Baltic Sea to a good environmental state, the Baltic Sea Action Plan (BSAP), regulating the waterborne and airborne nutrient input, was adopted by all states surrounding the Baltic Sea. However, at the moment, no significant shrinking of the hypoxic area is observed. In this study, two scenario simulations of the future state of the deep parts of the central Baltic Sea (deeper than 70 meters) were carried out, utilizing a 3-dimensional numerical model. Climate change effects on meteorology, hydrology, and oceanic state were not included. We focused on O2 and H2S sources and sinks under different nutrient input scenarios. We found that under the BSAP scenario, all subbasins in the central Baltic Sea, especially the northern and western Gotland Basin, show significant improvement, namely, oxygenation and oxidation of the deposited reduced material, ceasing its advection to the upper layers and neighboring basins. We found that the nutrient loads are responsible for more than 60% and 80% of the O2 and H2S sources and sinks variability, respectively, at the interannual time scale. We showed that the Baltic Sea could return to the initial state in 1948, but under the more rigorous 0.5 BSAP scenario (nutrient input is halved compared to the BSAP). However, since we observed no hysteresis effect, the system would probably reach the initial state but over a timeframe longer than the 71-year future simulation period.

Influence of oxygen/argon duoplasmatron synergistic modification on the mechanical properties of UHMWPE/vinyl ester composites

AbstractThis study reveals double plasma modification of ultra‐high molecular weight polyethylene (UHMWPE) fibers by oxygen/argon duoplasmatron source to investigate the synergistic effect of double plasma mixture on the mechanical performance of UHMWPE/vinyl ester laminated composites. The single‐factor experiment was used to determine the preparation process parameter range. The modified fiber was characterized and mechanical properties of UHMWPE/vinyl ester composites were evaluated. The results showed that the UHMWPE fiber modified by double plasma treatment with oxygen/argon duoplasmatron source exhibited more hydroxyl groups than untreated fiber and the single plasma‐modified fiber with oxygen source, and the surface water adsorb capacity was significantly improved, which contributed to the combination of resin and fiber surface. The tensile strength of the composite with double plasma modification increased to 380.48 MPa, which was higher than untreated and oxygen plasma treated samples by 36.9% and 18.9%, respectively. The GIC value was even 78.1% higher than that of oxygen plasma‐treated sample, and the interlaminar shear strength was increased by 19%. In terms of low‐velocity impact response, the absorbed energy of double plasma modified composites was increased, confirming that the mechanical resistant performance was enhanced by the modification with oxygen/argon duoplasmatron source.

Metal‐ and Additive‐Free Electrochemical Oxidation of Benzylic C−X Bonds to Carbonyl Groups

AbstractA scalable electrochemical strategy for oxidation of various benzylic C−X bonds to carbonyl groups was achieved. The protocol runs under mild reaction conditions and air atmosphere in a simple undivided electrolysis cell, H2O as oxygen source, and cheap graphite plates as both anode and cathode. In addition, the electrolysis strategy features good functional groups tolerance for selectively generating structure versatile ketones, aldehydes, and esters.

Water-promoting effect on reaction selectivity in the photocatalytic oxidation of sulfides to sulfoxides on TiO2

During TiO2-based photocatalysis, the presence of water usually leads to the unselective degradation of organic compounds due to the uncontrollable formation of water-derived radical species. Here we report that the presence of water dramatically enhances the selectivity in photocatalytic oxidation of sulfides to sulfoxides over TiO2. H218O-isotope labelling experiments reveal that both O2 and H218O contribute to the oxygen atoms in the formed sulfoxides and sulfones. Moreover, at the beginning of the oxidation of sulfides, water serves as the main source of the oxygen atom, while the contribution of O2 increases with the irradiation time. We uncover two roles of water in sulfides oxidation: to act as oxygen source in the oxidation of sulfides to sulfoxides; to provide protons to inhibit the further oxidation of sulfoxides. This study deepens our understanding of roles of water in photocatalytic oxidation of sulfides and offers a new strategy to optimize photocatalytic selective oxidation.

Distribution of Oxygen Tension on Microvessels and in Tissue of Rat Brain Cortex at Severe Arterial Hypocapnia

Arterial hypocapnia (AH), induced by voluntary or forced hyperventilation of the lungs, is accompanied by a decrease in cerebral blood flow (due to an increase in the arteriole tone) and an increase in the affinity of hemoglobin for oxygen. As a result, an insufficient oxygen supply to cortical tissue take place and zones with a critically low oxygen tension (pO2) are formed in brain tissue. The distribution of pO2 to cerebral cortex during AH has not been studied enough. The aim of the work was to evaluate the effectiveness of oxygen supply to brain tissue at the level of arterial and venous microvessels at AH. To do this, the following tasks were set: 1) to study the distribution of the pO2 on the arterial and venous microvessels of the rat cerebral cortex; 2) to analyze tissue pO2 profiles near the walls of these microvessels. On anesthetized Wistar rats under conditions of forced hyperventilation (PaCO2 = 17.1 ± 0.7 mm Hg), the distribution of oxygen tension on the wall of pial and radial arterioles with a lumen diameter of 7–70 μm and on the wall of pial and ascending venules with a lumen diameter of 7–300 µm was studied. In tissue, near the wall of cortical arterioles and venules with a lumen diameter of 10–20 μm, tissue pO2 profiles were measured. Measurements of pO2 during spontaneous breathing of the animal with air served as a control. All pO2 measurements were made using platinum polarographic microelectrodes with a tip diameter of 3–5 μm. Visualization of the electrode tip and microvessels was carried out using a LUMAM-K1 microscope with epiobjectives of the contact type. This work presents for the first-time direct measurements of pO2 on the walls of arterioles and venules of the rat cerebral cortex and in tissues at different distances from the walls of these microvessels at AH. It has been shown that AH results in significant decrease in the oxygen supply to cerebral cortex, that is manifested by a significant drop of the pO2’s on venous microvessels and in tissue in the immediate vicinity of the studied microvessels. It has been shown, that the role of arterioles as a direct source of oxygen to brain tissue, is significantly reduced during arterial hypocapnia. Forced hyperventilation results in significant deterioration of oxygen supply to cerebral cortex, despite elevated pO2 values in the systemic arterial blood and in blood of systemic cerebral veins (sagittal sinus).

Copper Nanoparticles Supported on ZIF-8: Comparison of Cu(II) Reduction Processes and Application as Benzyl Alcohol Oxidation Catalysts.

We report the synthesis of a stable heterogeneous catalyst based on copper metal nanoparticles with oxidized surface supported on ZIF-8 for the oxidation of benzyl alcohol under mild temperature and using air as a sustainable oxygen source as well as for the implementation of the tandem "one-pot" catalytic system allowing the sustainable synthesis of benzylidene malononitrile. The influence of the reduction process applied to form the nanoparticle upon the catalyst texture and its performances was extensively examined. After ZIF-8 impregnation with a copper chloride precursor, the reduction of cupric ions into Cu0 nanoparticles was carried out according to two procedures: (i) by soaking the solid into a solution of NaBH4 and (ii) by submitting it to a flow of gaseous H2 at 340 °C. The in-depth physicochemical characterization and comparison of the resulting two types of Cu/ZIF-8 materials reveal significant differences: the reduction with NaBH4 led to the formation of 16 nm sized Cu0 nanoparticles (NP) mainly localized on the external surface of the ZIF-8 crystals together with ZnO nanocrystallites, while the reduction under H2 flow resulted in Cu0 nanoparticles with a mean size of 22 nm embedded within the bulk of ZIF-8 crystals. More, when NaBH4 was used to reduce cupric ions, ZnO particles were highlighted by high-resolution microcospy imaging. Formation of ZnO impurities was confirmed by the photoluminescence analysis of ZIF-8 after NaBH4 treatment. In contrast, ZnO was not detected on ZIF-8 treated with H2. Both types of Cu0 NPs supported on ZIF-8 were found to be active as catalysts toward the aerobic oxidation of benzyl alcohol under moderate temperature (T < 80 °C) and using air as a sustainable O2 source. Benzaldehyde yield of 66% and selectivity superior to 90% were obtained with the Cu/ZIF-8 catalyst prepared under H2 flow after 24 h under these conditions. The same material could be recycled 5 times without loss of activity, unlike the catalysts synthesized with NaBH4, as a result of the leaching of the surface copper NPs over the consecutive catalytic cycles. Finally, the most stable catalyst was successfully implemented in a tandem "one-pot" catalytic system associating benzyl alcohol oxidation and Knoevenagel condensation to synthesize benzylidene malononitrile.

A novel method for CO2 injection direct smelting vanadium steel: Dephosphorization and vanadium retention

Abstract A novel method for CO2 injection direct smelting vanadium steel (CIDSVS) is proposed. Achieving selective oxidation of phosphorus is essential for the applicability of the suggested process. Under the guidance of thermodynamics, the mechanisms of CO2 injection dephosphorization and vanadium retention were investigated with CO2 flow rate and dephosphorization slag composition as experimental variables. The results indicate that CO2 as an oxygen source can remove 73.8% of phosphorus, while the oxidation rate of vanadium is 17.5%. The dephosphorization process can be divided into two stages: FeO- and CO2-dominated experimental processes. In the initial stage of slag feeding, [V] and [P] undergo fast oxidation, and the oxidation amount is positively correlated with the initial FeO content. The high basicity (CaO/SiO2 ratio) reduces the activity of V2O3 in the slag and promotes the oxidation of [V]. Under the experimental conditions of 1,400°C, the optimal conditions were determined to be a CO2 flow rate of 1.5 mL·g−1·min−1, a FeO content of 40%, and a basicity B of 2.5. Following the CIDSVS steelmaking operation, 80% of the vanadium is retained, and the impurity elements fulfill the specifications for steel. This method enhances vanadium utilization and is environmentally friendly.

Integrated Geology, mineralogy, element and C–O–S–Pb isotopes characteristics elucidate ore genesis of the world-class huoshaoyun Zn–Pb deposit in Karakoram Area, Xinjiang, Northwest China

The Huoshaoyun carbonate-hosted non-sulfide Zn–Pb deposit in the Karakoram area, northwest China, provides an excellent setting for investigating the origin of this type of deposit. Here, geology, mineralogy, elements, and C–O–S–Pb isotopes evidence are presented to constrain the ore genesis of the Huoshaoyun deposit. Two orebodies occur in limestone of the Longshan Formation, which exhibit laminated, banded, and brecciated textures. Ore minerals of the Huoshaoyun deposit are dominated by smithsonite and cerussite, with subordinate galena and pyrite. From early to late, ore formation is divided into three stages, which are sulfide stage, oxidation stage I and oxidation stage II. The C–O isotopic compositions of smithsonite (δ13CPDB: –0.70‰ to 4.50‰, δ18OSMOW: 23.30‰ – 25.20‰), cerussite (δ13CPDB: –3.00‰ to –1.80‰, δ18OSMOW: 10.60‰ to 13.10‰), mineralization stage calcite (δ13CPDB: 0.90‰ to 2.80‰, δ18OSMOW: 12.40‰ to 24.80‰) and calcite within wall-rocks (δ13CPDB: –0.30‰ to 2.60‰, δ18OSMOW: 13.20‰ to 25.60‰) indicate that the carbon and oxygen source of the Huoshaoyun deposit are closely related to the sedimentary strata, and the minerals have experienced intense TSR effect of organic matter and influenced by meteoric water to a greater extent. Compared with gypsum in the Longshan Formation (δ34SV-CDT: 17.10‰ and 17.20‰) and veined gypsum near the orebodies (δ34SV-CDT: –26.30‰ to –18.50‰), galena and pyrite both enrich negative sulfur isotopes with δ34SV-CDT values ranging from –35.60‰ to –13.00‰, which reveal that the sulfur in the Huoshaoyun deposit was derived from low-temperature bacterial reduction of evaporative sulfate. The uniform Pb isotopic data of galena, cerussite, and anglesite (208Pb/204Pb: 38.857 – 38.935, 207Pb/204Pb: 15.677 – 15.694, 206Pb/204Pb: 18.515 – 18.552) from the Huoshaoyun deposit display linear trends in Pb isotope diagrams, which imply that the galena, cerussite, and anglesite should have been exposed to a series of cogenetic evolutionary processes and shared the same lead sources with significant upper crust and orogenic contribution. In comparison with Pb isotopic data of regional strata (208Pb/204Pb: 38.530 – 39.695, 207Pb/204Pb: 15.579 – 15.883, 206Pb/204Pb: 18.290 – 20.035), the combination of these regional strata can provide the enough metals for mineralization and induce the Pb isotopic characteristics evolving to the present model in the Huoshaoyun deposit. In summary, the ore-forming materials are mainly sourced from regional strata, and the Huoshaoyun deposit is a supergene MVT deposit-a new non-sulfide deposit type in China.

Improving efficiency and reducing enzyme inactivation during lipase-mediated epoxidation of α-pinene in a double-phase reaction system.

Chemoenzymatic epoxidation of olefin mediated by lipase is a green and environmentally friendly alternative process. However, the mass transfer barrier and lipase deactivation caused by the traditional organic-water biphasic reaction system have always been the focus of researchers' attention. To overcome these issues, we investigated the effects of reaction temperature and two important substrates (H2O2 and acyl donor) on the epoxidation reaction and interfacial mass transfer. As a result, we determined the optimal reaction conditions: a temperature of 30°C, 30wt-% H2O2 as the oxygen source, and 1M lauric acid as the oxygen carrier. Additionally, by simulating the conditions of shaking flask reactions, we designed a batch reactor and added a metal mesh to effectively block the direct contact between high-concentration hydrogen peroxide and the enzyme. Under these optimal conditions, the epoxidation reaction was carried out for 5h, and the product yield reached a maximum of 93.2%. Furthermore, after seven repetitive experiments, the lipase still maintained a relative activity of 51.2%.

Contrasting responses of the ocean’s oxygen minimum zones to artificial re-oxygenation

Studies assessing potential measures to counteract the marine deoxygenation attributed to anthropogenic activities have been conducted in a few coastal environments and at regional scale, but not yet on a global scale. One way toward global scale artificial oxygenation would be to use oxygen produced as a by-product from hydrogen-production through electrolysis. The low-carbon footprint renewable production of hydrogen from offshore wind energy offers such a possibility. Here, we assessed the potential of this artificial oxygenation method on a global scale using a coupled physical-biogeochemical numerical model. The anthropogenic oxygen source scenario assumes worldwide adoption of hydrogen, considering demographic changes and the feasibility of offshore wind turbine deployment. Following this scenario, artificial oxygenation had a negligible effect on the overall oxygen inventory (an increase of 0.07%) but showed a reduction in the overall volume of Oxygen Minimum Zones (OMZs) between 1.1% and 2.4%. Despite the decrease in the mean OMZ volume globally, OMZs display distinct and contrasting regional patterns notably due to the oxygen impacts on the nitrogen cycle. Artificial oxygenation can inhibit denitrification resulting in a net gain of nitrate that promotes locally and remotely increased biological productivity and consequent respiration. Increased respiration could ultimately lead to an oxygen loss at and beyond injection sites as in the Tropical Pacific and Indian Ocean and particularly expand the Bay of Bengal OMZ. In contrast, the tropical OMZ shrinkage in the Atlantic Ocean is attributed to oxygen enrichment induced by advective transport into the OMZ, while the absence of denitrification in this area precludes any biochemical feedback effect on oxygen levels. These results suggest that the impacts of artificial oxygenation on oxygen concentrations and ecosystems are highly non-linear. It can produce unexpected regional responses that can occur beyond the injection sites which make them difficult to forecast.

Visible-Light-Induced Regioselective Radical Oxo-Amination of Alkenes with O2 as the Oxygen Source.

An efficient and novel visible-light-induced oxo-amination of terminal alkenes for the construction of α-amino ketones with easily accessible and green O2 as the oxygen source has been developed. The transformation possesses the advantages of operational simplicity, a broad substrate scope, high atom economy, and mild reaction conditions. The mechanistic studies reveal that an energy transfer process probably occurs in the initial stage, and the reaction proceeds via β-scission of the alkoxyl radical species.

Enhancing the Activity of Cu-MOR by Water for Oxidation of Methane to Methanol

As clean energy, methane has huge reserves and great development potential in the future. Copper zeolites are efficient in the oxidation of methane to methanol. Water has been confirmed as a source of oxygen to regenerate the copper-zeolite active sites to enable selective anaerobic oxidation of methane to methanol. In this work, we report that the methanol yield increased from 36 μmol/g (Cu-MOR1) to 92 μmol/g (Cu-MOR1-water) as a result of water enhancing the activity of copper ion-exchange mordenite catalyst. We show for the first time that water could convert inactive copper species into active copper species during catalyst activation. A combination of the XPS, FTIR, and NMR results indicates that water dissociates and then converts ZCuIIZ into ZCuII(OH) (where Z indicates framework O (Ofw) bonded to one isolated Al in a framework T-site, i.e., 1Al) and simultaneously produces a Brönsted acid site during catalyst activation. This finding can be used to tune the state of copper species and design highly active copper-zeolite catalysts for methane oxidation to methanol.

Peran Perempuan Dalam Pelestarian Lingkungan Menggunakan Sistem Agroforestri

Indonesia, especially Binjai City, uses an agroforestry system by utilizing the land of the residents of Binjai City by planting several cultivated plants, especially horticultural annuals and forest trees. The goal is to reduce the use of chemical pesticides and get the yield of land planted with horticultural crops in a relatively fast time, compared to forest crops whose productivity is relatively long. The sad thing is that the land will cause soil damage and will not become one of the providers of oxygen sources (O2) on Earth due to the reduced number of trees planted. There are also several other disadvantages, namely the competition between trees and horticultural crops in terms of fighting for nutrients and sunlight and the last weakness is the increasing labor costs, especially the role of women. The problem raised in this study is the role of women in environmental conservation using the Agroforestry system. The method carried out in this study is an observation method using a qualitative descriptive method that analyzes the problem under study. The result of her research is that the Government must conduct counseling or presentation of material about the Agroforestry system to women directly so that it is easier to understand

CuII-Catalyzed cis-Selective Synthesis of Ketoepoxides from Phenacyl Bromides and Water.

A verity of α,β-ketoepoxides was synthesized using a CuII-catalyzed oxidative C-C/O-C coupled cyclization strategy with high yield and cis-selectivity. Water is used as the source of oxygen and phenacyl bromide as the carbon in the valuable epoxides. The self-coupling method was extended to cross-coupling between phenacyl bromides with benzyl bromides. A high cis-diastereoselectivity was observed in all the synthesized ketoepoxides. Control experiments and density functional theory (DFT) study were performed to understand the CuII-CuI transition mechanism.