Different Types Of Oxides Research Articles

Investigating the High Temperature Tribological Efficacy of AlCoCrFeNiTi High Entropy Alloy Coating

Abstract The current work elucidates the tribological behavior of thermally sprayed AlCoCrFeNiTi high entropy alloy coatings under various temperatures of 200 °C, 400 °C, and 600 °C. Typically, most metallic alloys demonstrate softening and an increased wear-rate when exposed to extreme temperatures under loaded weight. The atmospheric plasma sprayed high entropy alloy coating exhibited minimal wear mass loss at high temperatures. The data analysis reveals the development of a tribolayer that facilitates a reduced mass loss of 15.34% in the alloy at 600 °C. The examination of the wear scars under field emission scanning electron microscopy analysis reveals the presence of an adhesive layer, wear debris, craters, and scratches. The existence of different types of oxides on the abraded surfaces was confirmed by the results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results support the effectiveness of AlCoCrFeNiTi alloy coatings in enhancing wear resistance under extreme conditions.

Photothermal Catalytic Degradation of VOCs: Mode，System and Application.

Human production and living processes emit excessive VOCs into the atmosphere, posing significant threats to both human health and the environment. The photothermal catalytic oxidation process is an organic combination of photocatalysis and thermocatalysis. Utilizing photothermal catalytic degradation of VOCs can achieve better catalytic activity at lower temperatures, resulting in more rapid and thorough degradation of these compounds. Photothermal catalysis has been increasingly applied in the treatment of atmospheric VOCs due to its many advantages. A brief introduction on the three modes of photothermal catalysis is presented. Depending on the main driving force of the reactions, they can be categorized into thermal-assisted photocatalysis (TAPC),photo-assisted thermal catalysis (PATC) and photo-driven thermal catalysis (PDTC). The commonly used catalyst design methods and reactor types for photothermal catalysis are also briefly introduced. This paper then focuses on recent developments in specific applications for photothermal catalytic oxidation of different types of VOCs and their corresponding principles. Finally, the problems and challenges facing VOC degradation through this method are summarized, along with prospects for future research.

Stability of the Glycated Amino Acid 6-(2-Formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine (Pyrraline) During Oxidation.

Food proteins may be modified during processing and storage through reactions with reducing sugars (Maillard reaction, glycation) or by reactive oxygen species (protein oxidation). Little is known about particular reactions at the interface of glycation and oxidation. In the present study, the glycated amino acid pyrraline (6-(2-formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine) and the proteinogenic amino acids tyrosine and tryptophan were subjected to different types of oxidation. The stability of the amino acids was assessed by HPLC with UV detection, whereas oxidation products were assigned by HPLC with triple quadrupole or time-of-flight mass spectrometric detection. Conditions that lead to oxidation of aromatic proteinogenic amino acids can also lead to oxidation of pyrraline. Pyrraline was particularly unstable in the presence of permanganate, hypochlorite, and under hydroxyl radical-generating conditions (iron, ethylenediaminetetraacetic acid, ascorbic acid). Evidence obtained by high-resolution mass spectrometry revealed the oxidation of pyrraline to 6-(2,5-diformyl-1-pyrrolyl)-l-norleucine, 6-(2-carboxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine, 6-(2-formyl-5-carboxy-1-pyrrolyl)-l-norleucine, and 6-(2,5-dicarboxy-1-pyrrolyl)-l-norleucine in the presence of potassium permanganate. The latter product was isolated by semipreparative HPLC and characterized by NMR. Under hydroxyl radical-generating conditions, pyrraline is hydroxylated at the ring under formation of 6-(2-formyl-4-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine or 6-(2-formyl-3-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine. This study shows that the so-called "advanced glycation end products" are no end products of the Maillard reaction, but may undergo further chemical degradation reactions.

Detritiation of the Organic Material in the MSO Process

Tritium is a radioactive isotope of hydrogen, and due to its limited supply and related high price, it is necessary to recover it from tritiated materials via detritiation technologies. The number of tritiated materials arises during fusion. Tritium from fusion reactors is deposited in the outer layer of plasma-facing materials, which must be dealt with during maintenance or decommissioning processes. A second source of waste is laboratory equipment that could be contaminated with tritium. High-temperature treatment in an oxidation environment can achieve the release of tritium from metals or organic materials. The tritiated vapor is then captured in a series of water bubblers and reprocessed into pure T2. One of the high-temperature methods is molten salt oxidation (MSO), which uses high temperatures, alkaline salt, and an oxidative environment for flameless oxidation of different types of waste. This work aimed to simulate the detritiation processes of tritiated organic materials in MSO technology. First, a series of experiments with D2O absorbed in ion resins was conducted. The organic waste was decomposed within the molten salt, and the flue gas was measured to determine the oxidation efficiency. The D2O was captured in a series of water bubblers, and the water was then analyzed with attenuated total reflectance (ATR)–Fourier transform infrared spectroscopy (FTIR). The results showed that all deuterium in the form of D2O was caught in the first water bubbler. The capture efficiency ranged from 22.32% to 61.13%. The lower efficiency capture can be explained as D2O in water can form a HDO molecule and its correct determination is problematic. The second type of experiment was carried out with T2O with an activity of 851 Bq and with tritiated oil with an activity of 2495 Bq. The T2O was added to the set amount of ion resins and dosed into MSO. A peristaltic pump dosed the tritiated oil. The flue gas was measured to determine oxidation efficiency, and the T2O was captured within the water bubblers. The water was analyzed with liquid scintillation spectroscopy. The capture efficiency ranged between 76.42% to 97.87%. The results showed that this technology is suitable for the detritiation of tritiated organic materials.

Investigation on the high-temperature oxidation behavior and mechanism of laser-cladded Inconel625 coating at various temperatures

This study examines the high-temperature oxidation behavior of laser-clad Inconel 625 coatings under different temperature and time conditions. The coating's microstructure, compositional elements, and oxidation products have been characterized through various analytical methods, including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and Laser Confocal Microscopy. The experimental results showed that as the temperature increased in the isothermal oxidation process, the mass of the coatings increased, and the mass gain followed a parabolic relationship with oxidation time. The rate constant exhibited an exponential relationship with temperature. Both oxidation time and temperature had significant effects on the composition and formation of the oxide layer. At lower temperatures, the oxidation process is slow, with an oxidation weight gain of approximately 0.00053 mg/cm2. However, above 600 °C, the oxidation films began to form rapidly, increasing by 0.0169 mg/cm2. Moreover, as the temperature rose, different types of oxides formed at various temperature regimes. At 800 °C, the oxidation film had a thickness of approximately 3.75 μm and a weight gain of 1.19921 mg/cm2. At this point, oxides such as Cr2O3, Nb2O5, NiO, and spinel NiCr2O4 appeared. When the temperature reached 1000 °C, the oxidation film expanded to approximately 63.88 μm in thickness, with a weight gain of 3.5326 mg/cm2. The oxidation products at this temperature were Cr3O4 and spinels NiCr2O4, CrNbO4, NiNb2O6. These findings contribute valuable insights for understanding the dynamic behavior and assessing the service life of laser-clad nickel-based alloy coatings subjected to high-temperature oxidation corrosion.

Modulation of optical band gap and conductivity of polyindoles with concentrations of FeCl3 and APS

Conducting Polyindoles (PIn-I and PIn-II) samples were synthesized via chemical oxidative polymerization in aqueous solution at a range of concentrations (0.3–0.9 M) of anhydrous FeCl3 and Ammonium persulfate (APS) at 25 ± 1 °C. Techniques such as FTIR spectrograph confirm various bond absorptions which give the identity of PIns, the morphology has been examined by SEM and XRD, while the thermal analysis of the prepared sample was studied by employing TGA-DSC. UV–Vis spectroscopy has been used to analyze complex optical parameters like band gap, refractive index, dielectric constant, and optical conductivity. The produced PIns exhibit absorption around 340–410 nm and results in the optical band gap in the range of 2.906 to 2.929 eV for the PIn-I series (with FeCl3) and 2.673 to 2.734 eV for the series of PIn-II (with APS). The samples synthesized employing 0.3 M FeCl3 and 0.9 M APS were found to have the lowest optical band gap energies of 2.906 eV and 2.673 eV, respectively. The experimental studies reveal that the optical conductivity, particle size, and crystallinity of PIn can be optimized with the different types of oxidants and their varying concentrations. The results conclude that the oxidizing agents having high reduction potential offer better electron transport and thus lower band gap and high optical conductivity. Due to the above-mentioned optical band gaps and high environmental stability, PIns have potential applications in optical devices.

Chemical Oxidation and Characterization of Carbon Nanotubes of Different Types for Improving the Efficiency of REE Preconcentration for Their Subsequent Determination in Geological Samples

Various methods for the oxidation of different types of carbon nanotubes (CNTs) in nitric acid and a mixture of nitric and sulfuric acids at various temperatures and durations of exposure are studied. Oxidation conditions that provide the high sorption activity of sorbents with respect to REE are found. Oxidized CNTs are characterized by acid-base titration and scanning electron microscopy, and the electrokinetic (ζ) potential of nanotube suspensions is determined as a function of pH. The elemental composition of CNTs is determined by ICP MS/AES methods. The sorption capacity of the oxidized CNTs with respect to a wide range of elements is determined. Their unique selectivity with respect to REE is revealed. A possibility of using oxidized CNTs for the efficient sorption preconcentration of REE with the aim to determine their ultralow concentrations in rocks is proved.

Efficient catalytic oxidation of chlorinated volatile organic compounds over RuO2-WOx/Sn0.2Ti0.8O2 catalysts: Insight into the Cl poisoning mechanism of acid sites

The development of catalysts with high activity, selectivity, and durability is crucial for the catalytic oxidation of chlorinated volatile organic compounds (CVOCs). Although acid-modified supports are widely used in catalysis to improve the catalytic activity at low temperature, the acid sites are easily deactivated by Cl poisoning, and the poisoning mechanism remains unclear. Here, a series of RuO2-WOx/Sn0.2Ti0.8O2 catalysts were synthesized for dichloromethane (DCM) catalytic oxidation. Spectroscopic characterizations revealed that the loading amount of tungsten oxide highly affects the structure of the surface species and, consequently, the low-temperature catalytic activity. SEM, XRD and DFT calculations elucidated that the loss of tungsten species in the form of WO2Cl2 is the main reason for the catalyst deactivation. By loading RuO2, the loss of tungsten species could be effectively avoided via the Deacon reaction. The cordierite catalyst exhibits excellent catalytic activity for the oxidation of different types of CVOCs.

Environmental impacts of canola (Brassica napus L.) production in Iran: a case study in Alborz province

In this study, the environmental impacts of rapeseed production were studied using the SimaPro software. The initial data were collected from 30 farmers in the Alborz Province by face-to-face questionnaire method. The selected functional unit (FU) was one Mton-1 rapeseed production. Five environmental indices were evaluated, including the potential of abiotic depletion, acidification, eutrophication, global warming and ozone layer depletion. To produce each ton of rapeseed, 84 kg of nitrogen, 63 kg of phosphate, 63 kg of potassium, 133.5 l of diesel fuel and 586 kW of electricity were used. Also, the CO2, CO, N2O and NOX (different types of oxides of nitrogen) emissions were about 361, 4.1, 11.5 and 4.8 kg per ton of rapeseed respectively. The results indicate that the global warming potential amounts to 1629.52 kg CO2 eq. Also, the acidification and eutrophication potentials were found to be 8.31 kg SO2 eq. and 2.73 kg PO4 eq. respectively. It was also revealed that the chemical fertilizers had the highest contribution among the evaluated inputs within the rapeseed growing period. Overall, this study showed that reducing the consumption of chemical fertilizers, especially nitrogen-based ones, is important for reducing environmental footprints in rapeseed production.

The Interaction of K and O2 on Au(111): Multiple Growth Modes of Potassium Oxide and Their Catalytic Activity for CO Oxidation.

In industrial catalysis, alkali cations are frequently used to promote activity or selectivity. Scanning tunneling microscopy, ambient-pressure X-ray photoelectron spectroscopy, and density-functional calculations were used to study the structure and reactivity of potassium oxides in contact with the Au(111) surface. Three different types of oxides (K2 O2 , K2 O and KOy with y<0.5) were observed on top of the gold substrate at 300-525 K. Initially, small aggregates of K2 O2 /K2 O (1-2 nm in size) were seen at the elbows of the herringbone structure. After increasing the K coverage (>0.15 ML), large islands of the oxide (20-40 nm in size) appeared. These islands contained a mixture of K2 O and KOy (y<0.5). A key correlation was found involving the structure, oxidation state, and chemical activity of the alkali oxide. The small aggregates of potassium oxide had a very high catalytic activity for the oxidation of CO, being much more than plain promoters.

The Interaction of K and O2 on Au(111): Multiple Growth Modes of Potassium Oxide and Their Catalytic Activity for CO Oxidation

AbstractIn industrial catalysis, alkali cations are frequently used to promote activity or selectivity. Scanning tunneling microscopy, ambient‐pressure X‐ray photoelectron spectroscopy, and density‐functional calculations were used to study the structure and reactivity of potassium oxides in contact with the Au(111) surface. Three different types of oxides (K2O2, K2O and KOy with y&lt;0.5) were observed on top of the gold substrate at 300–525 K. Initially, small aggregates of K2O2/K2O (1–2 nm in size) were seen at the elbows of the herringbone structure. After increasing the K coverage (&gt;0.15 ML), large islands of the oxide (20–40 nm in size) appeared. These islands contained a mixture of K2O and KOy (y&lt;0.5). A key correlation was found involving the structure, oxidation state, and chemical activity of the alkali oxide. The small aggregates of potassium oxide had a very high catalytic activity for the oxidation of CO, being much more than plain promoters.

Recent advances in non-noble electrocatalysts for oxidative valorization of biomass derivatives

Electrocatalysis is deemed as a promising approach for sustainable energy conversion and chemical production. Although a variety of cathode reactions (e.g., hydrogen evolution and CO2/N2 reduction) produce valuable fuels and chemicals, the extensively studied oxygen evolution reaction (OER) at anode only generates O2, which is not a high-value product. Substituting the OER with thermodynamically more favorable biomass derivative oxidation reactions (BDORs) not only enables energy-saving electrocatalysis, but also provides value-added anode products. Recent achievements have demonstrated that non-noble electrocatalysts are promising for BDORs. Herein, we provide a comprehensive review on recent achievements in the field of electrochemical BDORs catalyzed by non-noble catalysts. We start by summarizing the electrocatalytic oxidation of different types of biomass-derived substrates, aiming to show the advantages of the electrocatalytic pathway and to introduce the state-of-the-art non-noble catalysts. The reaction mechanisms of non-noble-material-catalyzed BDORs are then summarized and classified into three types according to the acceptor of hydrogen species during the dehydrogenation of biomass derivatives. Subsequently, discussions are devoted to the strategies for promoting the performances of non-noble electrocatalysts. Finally, we propose our opinions regarding future trends and major challenges in this field.

Developments in the investigation of nitrogen and oxygen stable isotopes in atmospheric nitrate

Under the influence of human activities and the rapid development of industry and agriculture, atmospheric nitrate (NO − 3 ) pollution is becoming increasingly serious and has become an environmental problem worldwide. The stable isotopic composition of atmospheric NO − 3 (δ 15 N, δ 18 O, and Δ 17 O) can provide a strong basis for understanding the atmospheric nitrogen cycle to effectively control atmospheric NO x pollution. In this work, the δ 15 N values associated with different sources of atmospheric NO − 3 , the seasonal variation characteristics of δ 15 N-NO − 3 , and the main influencing factors are reviewed. The δ 18 O and Δ 17 O values of different oxidants in the atmosphere and the spatiotemporal distribution characteristics and possible influencing factors of the δ 18 O and Δ 17 O values ​​of atmospheric NO − 3 are summarised. In addition, key advances in NO − 3 isotopic analysis technique is reviewed. Based on previous work, it is suggested that more attention should be given to the oxidative formation mechanism of NO − 3 (spatio-temporal differences in the isotopic compositions of different types of oxidants), the δ 15 N composition of different NO x sources, and the processes of formation, transport, depositional/chemical loss ofatmospheric NO − 3 with the help of observation and chemical models.

Hot corrosion behaviour of Inconel 738 superalloy in presence of NaCl, Na2SO4, V2O5

Superalloy are widely used for high temperature applications in diverse environment such as boilers, turbines and petrochemical industries for longer hours of operation. The application environment may have aggressive salts such as NaCl, Na2SO4, V2O5 which can catalase the hot corrosion thus affecting the normal working of the appliances. In present work, hot corrosion behavior of Inconel 738 superalloy studied by using cyclic hot corrosion test carried out at 700 °C for 10 cycles. For this study to know how the effect of salts on the alloy, each specimen was coated separately by NaCl, Na2SO4, V2O5 salt. After that, the coated specimens placed in the furnace. The cycle consists of 24Hr of heating at 700 °C in muffle furnace. Then, the specimens removed from the furnace and allowed to cool in the air environment. The weight gain after every cycle is measured and is used to determine the kinetics of hot corrosion. The graph of square of weight gain/Area Vs no of cycles was plotted. X-ray diffraction used to study the different types of oxides and compounds formed on the specimen surface. The morphology and electrochemical analysis of the specimens correlated to study the hot corrosion behavior. The rate constant (parabolic rate constant, KP) was determined from the weight gain data. The results showed that the specimen coated with Na2SO4 has lower corrosion as compare to the specimen coated with NaCl and V2O5 due to the presence of protective oxide such as Cr2O3, TiO2, Fe2O3, NiCr2O4, Ni3Ti formed on the specimen surface.

Wear and corrosion of Co-Cr coatings electrodeposited from a trivalent chromium solution: Effect of heat treatment temperature

Electrodeposition from a trivalent chromium bath was employed to obtain the cobalt‑chromium coatings with a thickness of ~25 μm. The effect of heat treatment temperature on characteristics, mechanical properties , and electrochemical behavior of the coatings, were examined. Heat treatment was performed in a wide range of temperatures (200–800 °C). Heat-treating below 400 °C increased the crystallinity of alloy coatings and had a negligible effect on nodular and cracked morphology. Raising the heat-treating temperature changed the X-ray diffraction patterns by thickening the surface oxide films , which consisted of different oxides (e.g., cobalt chromite spinel). The surface nodules were faded out above 700 °C. The heat-treating below 300 °C decreased the hardness and wear resistance of Co-Cr electrodeposits. The 400 °C heat-treated sample had the highest hardness of ~1000 HV, and the best tribological behavior. The weight loss and coefficient of friction of this sample were 24 and ~2 times smaller than the as-deposited coating. The hardness and wear resistance dropped again with further raising the heat-treating temperature. While detachment of coating during sliding occurred at low-temperature heat-treated samples, the abrasion was the main mechanism of material loss at those heat-treated at higher temperatures. According to the corrosion results, the optimum heat-treating temperature that the highest corrosion resistance could be achieved was 300–500 °C. The corrosion current density of 400 °C heat-treated coating was ~3.7 times smaller than the as-deposited Co-Cr film. • The relatively thick Co-Cr coatings were produced from a trivalent chromium bath. • Effect of heat treatment on Co-Cr films' characteristics and properties was studied. • Different types of oxides and morphologies were observed at various temperatures. • The 400 °C heat-treated sample showed the highest hardness and wear resistance. • Optimum heat treatment temperatures for the best corrosion resistance was 300–500 °C.

Efficient aerial oxidation of different types of alcohols using ZnO nanoparticle–MnCO3‐graphene oxide composites

Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle‐based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)‐based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle‐doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co‐precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature‐friendly oxidant under base‐free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, Energy dispersive X‐ray spectroscopy (EDX), Brunauer‐Emmett‐Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g−1.hr−1) with full convversion of BzOH and &gt;99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen‐possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity.

Sol–gel synthesis of Ni/Al2O3 catalysts for toluene reforming: Support modification with alkali, alkaline earth or rare-earth dopant (Ca, K, Mg or Ce)

In this study, the influence of alkali, alkaline earth or rare-earth dopant (i.e. Ca, K, Mg or Ce) addition in 10 wt% Ni/γ-Al2O3 catalyst were studied on the material physicochemical properties and catalytic activity. Twelve doped Ni/γ-Al2O3 catalysts were synthesized by sol–gel process in aqueous medium. One Ni/γ-Al2O3 catalyst without dopant was also synthesized as reference material. The addition of 1.5 wt% of alkali (i.e. Ca, K or Mg) did not influence the acido-basicity properties of the catalysts due to low interactions with the support. All samples doped with 1.5 wt% of oxide (i.e. Ca, K, Mg or Ce) presented a decrease of benzene selectivity up to 73% and a decrease of the amount of carbon deposit up to 40%. These results were attributed to a higher degradation of the intermediate compounds of toluene and the carbonaceous compounds because of a higher amount of H2O and CO2 molecules adsorbed on these oxides. Among the different compositions of Ni/γ-Al2O3 catalysts doped with two different types of oxides (i.e. K+Ca) showed the most interesting performances with an increase of 20% in conversion and a decrease of 10% in carbon deposition. Therefore, it showed that low-cost elements (as Ca and K) can be added in small amount to increase the catalytic properties without the need of the expensive ceria element.

The effect of support properties on n-octanol oxidation performed on gold – silver catalysts supported on MgO, ZnO and Nb2O5

Catalytic behaviour of supported nanometal catalysts for alcohols selective oxidation depends on the nature of the support and its surface. To identify the main feature that could explain these effects, supported mono- (Au) and bimetallic (AuAg) catalysts were prepared by using pure MgO, ZnO and Nb2O5, representative of three different types of oxides (basic, amphoteric and acidic, respectively), to get homogeneous metal-support interaction for each catalyst. The catalysts were characterized by XRD, N2 physisorption, TEM, UV–vis, XPS and 2-propanol decomposition as test reaction. It was found that the catalytic activity is influenced by the electron mobility between the gold nanoparticles and the support, which in turns depends on the intermediate electronegativity of the support. Selectivity in n-octanol oxidation was determined by redox properties of the gold species, the acid-base properties of the supports and the catalyst pretreatment. Silver addition modified the acid-base properties of the catalytic system, thus influencing the selectivity in n-octanol oxidation. Pretreatment of the catalyst (drying in air or thermal treatment in hydrogen flow) had a significant impact on its activity and selectivity.

Unsteady water functionalized oxide and non-oxide nanofluids flow over an infinite accelerated plate

The purpose of this communication is to examine the collective influence of heat and mass transfer on magnetohydrodyanmics (MHD) water functionalized oxide or non-oxide nanofluid flows through porous medium together with thermal radiation and chemical reaction effects. The Newtonian heating on the accelerated wall in the presence of different nanoparticles is considered first time and not explored in earlier investigations. To calculate the temperature and velocity fields, the Maxwell model for effective thermal conductivity with relatively large particles is used. Three types of base fluids namely water, kerosene and engine oil containing different types of oxide and non-oxide nanoparticles are taken for this study. Analytic solutions of the governing equations are obtained with the help of Laplace transform method (LTM). Some important cases such as free convection and motion of plate with variably accelerated, constant accelerated, uniform velocity as well as in the absence of free convection are obtained. Graphs are plotted to analyse the characteristics of different involved parameters on velocity, temperature and concentration.

Simple Hybrids Based on Mo or W Oxides and Diamines: Structure Determination and Catalytic Properties

Crystalline hybrid catalysts based on molybdenum or tungsten oxide and aliphatic diamines were synthesized via simple, eco-friendly reproducible methodologies, starting from commercially available and relatively inexpensive organic and inorganic precursors, and using water as solvent under mild conditions. The crystal structures of the obtained fine powdered solids were solved ab initio from powder X-ray diffraction data. The type of organic component (1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane) may play a structure-directing role. On the other hand, different metals (M = Mo, W) may lead to isostructural one-dimensional hybrids of the type MO3(L) with the same bidentate diamine ligand L. The prepared catalysts were investigated for the liquid phase oxidation of saturated and unsaturated hydrocarbons (cis-cyclooctene, cyclooctane), using different types of oxidants (O2, H2O2, tert-butyl hydroperoxide). Differences in catalytic performances associated with distinct structural features were investigated.Graphic