Microbial desulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene in dodecane and straight-run diesel oil

The desulfurization of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and their mixture by lyophilized cells ofPseudomonas delafieldii R-8 was studied in the presence of dodecane. The desulfurization rate for 4,6-DMDBT was found to be about 40% in comparison with that for DBT. The desulfurization process for DBT and 4,6-DMDBT proceeded simultaneously without preference for either one. The desulfurization rate for each compound was decreased when they were mixed together. The extent of desulfurization of 4,6-DMDBT was increased with the increase of cell concentration and the decrease of the volume ratio of oil-to-water used. The specific desulfurization rate for 4,6-DMDBT could be reached to 10.4 mmol sulfur kg⁻¹ (cell) h⁻¹ [approximately 0.33 mg sulfur g⁻¹ (cell) h⁻¹].Pseudomonas delafieldii R-8 showed high desulfurization capability for straight-run diesel oil (containing 1,807 mg/L of sulfur). About 1,000 mg/L of sulfur in diesel oil was removed by resting cells of this strain in 24 h of reaction. The specific desulfurization rate was 8.75 mmol sulfur kg⁻¹ (cell) h⁻¹.     

Temperature and Spatiotemporal Variability of Salicylihalamide A in the Sponge <Emphasis Type="Italic">Haliclona</Emphasis> sp.

The production of salicylihalamide A by the marine sponge Haliclona sp. was investigated. Samples of the two morphologies (green and brown) were collected from four locations covering approximately 1,200 km of coastline. Temporal variation between winter and summer was also examined at Bremer Bay. Chemical profiling by using liquid chromatography coupled with ultra violet detection and mass spectrometry showed that salicylihalamide A was produced only by the green morphology. Salicylihalamide A concentration was significantly correlated to water temperature but not to the size or depth of the sponge. Salicylihalamide A concentration was found to differ significantly among locations (Bremer Bay 13.5 μg g⁻¹, Hamelin Bay 11 μg g⁻¹, Rottnest Island 9.9 μg g⁻¹, and Jurien Bay 8.5 μg g⁻¹) partially accounted for by the influence of water temperature. A difference between seasons was also observed in Bremer Bay (summer concentration of 13.5 μg g⁻¹ vs. winter concentration of 8.2 μg g⁻¹). Environmental and physiological factors appear to be important in the production of salicylihalamide A by the green morphology. Additionally, the brown morphology does not produce salicylihalamide A, thus adding to the evidence that this morphology may be a different species.     

Cultivation impacts nitrogen transformation in Indian forest ecosystems

Two forests and two croplands, converted from the forest ecosystem were studied for 2 years to quantify inorganic N, nitrification, N-mineralization and microbial-N. The available N-pool ranged from 15.23 μg g⁻¹ to 19.84 μg g⁻¹, microbial-N from 20.6 μg g⁻¹ to 80.02 μg g⁻¹ with maximum values in summer season and minimum values in the rainy season. The trend for nitrification and N-mineralization was opposite to that of the size of available N-pool. Mean annual net nitrification rates ranged from 7.07 μg g⁻¹ month⁻¹ to 44.84 μg g⁻¹ month⁻¹ (0.17–1.39 μg g⁻¹ day⁻¹) and net N-mineralization from 6.56 μg g⁻¹ month⁻¹ to 48.53 μg g⁻¹ month⁻¹ (0.21–1.56 μg g⁻¹ day⁻¹). On an average, the pool of available N was slightly higher by 4.81%, while the microbial-N was declined substantially by 41.78% after the conversion of forest into cropland. Cultivation reduced the mean annual net nitrification and net N-mineralization, respectively by 50.71% and 47.67%. Interestingly, seasonal moisture content is negatively correlated to microbial-N and inorganic N and positively related to nitrification and N-mineralization.     

Cadmium removal from aqueous solutions using biosorbent <Emphasis Type="Italic">Syzygium cumini</Emphasis> leaf powder: Kinetic and equilibrium studies

Syzygium cumini L. leaf powder and Cd(II) loaded samples were characterized using FTIR and SEM techniques. The biosorption of cadmium ions from aqueous solution was studied in a batch adsorption system as a function of pH, contact time, adsorbate, adsorbent, anion and cation concentrations. The biosorption capacities and rates of transfer of cadmium ions onto S. cumini L. were evaluated. The kinetics could be best described by both linear and nonlinear pseudo-second order models. The isothermic data fitted to various models in the order Freundlich>Redlich-Peterson>Langmuir>Temkin. The maximum adsorption capacity of S. cumini L. leaves at room temperature was estimated to be 34.54 mg g⁻¹. The negative values of ΔG⁰ indicated the feasibility of the adsorption process. The endothermic nature was confirmed by the positive value of the enthalpy change (ΔH⁰=3.7 kJ mol⁻¹). The positive value of entropy change (ΔS⁰=16.87 J mol⁻¹ K⁻¹) depicted internal structural changes during the adsorption process.     

Adsorption of chromium(VI) and nickel(II) ions on acid- and heat-activated deoiled spent bleaching clay

De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone at temperatures between 200 and 800°C. The surface area of the heat-activated clay attained a maximal value of ≈120 m² g⁻¹ at temperatures between 400 and 500°C while the acid-heat-treated clay attained maximal surface area of ≈140 m² g⁻¹. The adsorption capacities of chromium [Cr(VI)] for both series studied increased as the activation temperature increased until 300°C and decreased again at higher temperatures. At lower pH, more than 95% of the Cr(VI) was absorbed in a solution with initial concentration of 1 mg L⁻¹ per gram of adsorbent activated at 300°C. The adsorption patterns followed Freudlich's isotherms. Two maximal values of adsorption capacities of nickel [Ni(II)] were observed at activation temperatures of 200 and 500°C for acid-treated samples, whereas these were at 200 and 700°C for the nonacid-treated samples. The amount of Ni(II) adsorbed increased with the pH of the solution for all samples studied. The maximal adsorption capacities of the adsorbents in solution containing initial Ni(II) concentration of 5 mg L⁻¹ per 0.5 g of adsorbent and at pH 6 were found to be 44 and 42%, respectively, for the acid-treated sample activated at 500°C and for the nonacid-treated sample activated at 700°C. They all obeyed both the Langmuir's and Freundlich's isotherms.     

Physico-Chemical Characterization of <Emphasis Type="Italic">Moringa concanensis</Emphasis> Seeds and Seed Oil

The present work reports the characterization and comparison of Moringa concanensis seed oil from Tharparkar (a drought hit area), Pakistan. The hexane-extracted oil content of M. concanensis seeds ranged from 37.56 to 40.06% (average 38.82%). Protein, fiber, moisture and ash contents were found to be 30.07, 6.00, 5.88 and 9.00%, respectively. The extracted oil exhibited an iodine value of 67.00; a refractive index (40 °C) of 1.4648; its density (24 °C) was 0.8660 mg mL⁻¹; the saponification value (mg of KOH g⁻¹ of oil) was 179.00; unsaponifiable matter 0.78%; color (1 in. cell) 1.90R + 19.00Y; and acidity (% as oleic acid) 0.34%. Tocopherols (α, γ, and δ) in the oil accounted for 72.11, 9.26 and 33.87 mg kg⁻¹, respectively. Specific extinctions at 232 and 270 nm were 3.17 and 0.65, respectively. The peroxide and p-anisidine values of the oil were found to be 1.75 and 1.84 meq kg⁻¹, respectively. The induction periods (Rancimat, 20 L h⁻¹, 120 °C) of the crude oil was 10.81 h and reduced to 8.90 h after degumming. The M. concanensis oil was found to contain high levels of oleic acid (up to 68.00%) followed by palmitic, stearic, behenic, and arachidic acids up to levels of 11.04, 3.58, 3.44 and 7.09%, respectively. The results of the present analytical study, compared with those for other Moringa species and different vegetable oils, showed M. concanensis to be a potentially valuable non-conventional seed crop for high quality oil.     

Ozonide ions on the surface of MgO nanocrystals

The adsorption properties of oxygen radicals on the surface of polycrystalline oxides can provide relevant information about the functionality of specific surface sites in oxidation catalysis. Using electron paramagnetic resonance spectroscopy, we investigated O₂ adsorption at MgO nanocrystal surfaces which were previously enriched with O⁻ radicals i.e. trapped hole centers. On dehydroxylated particle surfaces, two ozonide radical types O ₃ ⁻ were isolated as adsorbates and the related energies for O₂ adsorption were found to be 55 ± 5 kJ mol⁻¹ and 100 ± 5 kJ mol⁻¹. The respective adsorption sites are assigned to hole centers trapped on oxygen terminated corners and cation vancancies, respectively. In addition, O ₃ ⁻ ions were also employed as probes for electron trapping sites on partially hydroxylated sample surfaces. Five types of O⁻ radicals emerge from surface colour centre bleaching with N₂O, but only two of them adsorb O₂ at room temperature. A connection between the well-characterized (H⁺)(e^-) defect – an electron trapped in close vicinity of a nearby proton [Chiesa et al. J. Phys. Chem. B 109 (2005) 7314] – and one ozonide type which exhibits significant magnetic coupling with an adjacent proton, was established on the basis of their production parameter dependence. Although the g tensor of an O₃ ⁻ species reflects the properties of the radical itself rather than the structure of the adsorption site, the related signatures are proposed to serve also as spectroscopic fingerprints for catalytically relevant surface anion environments.     

Reaction between Hydrosulfide and Iron/cerium (hydr)oxide: Hydrosulfide Oxidation and Iron Dissolution Kinetics

Hydrosulfide oxidation and iron dissolution kinetics were studied at normal pressure, under inert (N₂) atmosphere, in a liquid–solid mechanically-stirred slurry reactor. The kinetic variables undergoing variations were: hydrosulfide initial concentration (0.90–3.30 mmol/L), oxide initial surface area (16–143 m²/L) and pH (8.0–11.0). The hydrosulfide consumption and products (thiosulfate and polysulfide) formation were quantified by means of capillary electrophoresis, while iron dissolution was monitored through atomic absorption spectroscopy. Most of Fe(II) produced at pH = 9.5 remained associated with the oxide surface in the time-scale of the experiments. The hydrosulfide oxidation by the iron/cerium (hydr)oxide was found to be surface-controlled, with rates (R_i) of both sulfide oxidation and Fe(II) dissolution expressed in terms of an empirical rate equation: R_i = k_i[HS⁻]_t=0^−0.5[A]_t=0[H⁺]_t=0^−0.5 , where k_i represents the apparent rate constants for the oxidation of HS⁻ (k_HS) or the dissolution of Fe(II) (k_Fe), [HS⁻]_{t = 0} is the initial hydrosulfide concentration, [A]_{t = 0} is the initial Fe/Ce (hydr)oxide surface area and [H⁺]_{t = 0} is the initial proton concentration. The rate constant, k_HS, for the oxidation of hydrosulfide at pH = 9.5 was (3.4219 ± 0.65) × 10⁻⁴ mol² L⁻¹ m⁻² min⁻¹, with the rate of hydrosulfide oxidation being ca. 10 times faster than the rate of Fe(II) dissolution (assuming a 1:2 stoichiometric ratio between HS⁻ oxidized and Fe(II) produced; k_Fe = (3.9116 ± 0.41) × 10⁻⁵ mol² L⁻¹ m⁻² min⁻¹).     

Synthesis of mesoporous silica templated by Pluronic F68 and its application in the immobilization of lipase

Mesoporous silica templated by Pluronic F68 was synthesized and characterized by TEM, N₂ adsorption–desorption isotherms and FT–IR spectra. The sample had a high specific surface area (761 m² g⁻¹) and the mean pore diameter was 4.7 nm, indicating that it can be used as porcine pancreatic lipase (PPL) support. The physical adsorption of PPL on this mesoporous material in phosphate buffer solution with different pH values has been studied. The maximum adsorbed amount was observed at pH 7.0 and amounted to 826 mg g⁻¹ and the maximum activity value of immobilized PPL was 227 μmol g⁻¹ min⁻¹. The optimal pH and temperature of the hydrolysis of triacetin for the immobilized PPL were at 8.0 and 45 °C, while they were at pH 7.0 and 35 °C for free PPL. The immobilized PPL showed excellent adaptability in higher pH and excellent heat resistance compared to free PPL. The retained activity of immobilized PPL was found to be ca. 50% of its original activity after the 5th reuse.     

Soil nitrogen response to coupling cover crops with manure injection

Coupling winter small grain cover crops (CC) with manure (M) application may increase retention of manure nitrogen (N) in corn (Zea mays L.), -soybean [Glycine max (L.) Merr], cropping systems. The objective of this research was to quantify soil N changes after application of liquid swine M (Sus scrofa L.) at target N rates of 112, 224, and 336 kg N ha⁻¹ with and without a CC. A winter rye (Secale cereale L.)-oat (Avena sativa L.) CC was established prior to fall M injection. Surface soil (0–20 cm) inorganic N concentrations were quantified every week for up to 6 weeks after M application in 2005 and 2006. Soil profile (0–120 cm in 5, 20-cm depth increments) inorganic N, total N, total organic carbon and bulk density were quantified for each depth increment in the fall before M application and before the CC was killed the following spring. Surface soil inorganic N on the day of application averaged 318 \textmg  \textN  \textkg ^{- 1}_\textsoil 318\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in 2005 and 186 \textmg  \textN  \textkg ^{- 1}_\textsoil 186\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}} } in 2006 and stabilized at 150 \textmg  \textN  \textkg ^{- 1}_\textsoil 150\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in both years by mid-November. Surface soil NO₃-N concentrations in the M band were more than 30 times higher in the fall of 2005 than in 2006. The CC reduced surface soil NO₃-N concentrations after manure application by 32% and 67% in mid- November 2005 and 2006, respectively. Manure applied at 224 kg N ha⁻¹ without a CC had significantly more soil profile inorganic-N (480 kg N ha⁻¹) in the spring after M application than manured soils with a CC for the 112 (298 kg N ha⁻¹) and 224 (281 kg N ha⁻¹) N rates, and equivalent inorganic N to the 336 (433 kg N ha⁻¹) N rate. These results quantify the potential for cover crops to enhance manure N retention and reduce N leaching potential in farming systems utilizing manure.     

Influence of the catalyst surface area on the activity and stability of Au/CeO2 catalysts for the low-temperature water gas shift reaction

The influence of the support surface area on the activity and stability/deactivation of Au/CeO₂ catalysts (2.7 wt% Au) in the water gas shift reaction in dilute water gas were investigated by kinetic measurements and in situ Diffuse Reflectance IR spectroscopy. For ceria support surface areas between 24 and 284 m² g⁻¹, the gold particle size is independent on the catalyst surface area (about 2.1 nm) up to 188 m² g⁻¹, and we found increased amounts of (i) Auⁿ⁺, (ii) Ce³⁺, (iii) OH groups, and (iv) carbon containing adsorbed side products such as formates and carbonates for increasing surface area supports. Consequences of these results on the mechanistic understanding of the reaction are discussed.     

Growth and eicosapentaenoic acid production byPhaeodactylum tricornutum in batch and continuous culture systems

Maximum specific growth rate (μ_max) ofPhaeodactylum tricornutum increased with increasing culture reactor surface-to-volume ratio. Values for μ_max of 0.647, 0.377 and 0.339 day⁻¹ were observed for the 75-mL tube, 5.6-L tank and the 16-L tank, respectively. Higher biomass was achieved in the 75-mL batch culture tube under continuous light as compared with light cycle conditions. Palmitic acid, palmitoleic acid and eicosapentaenoic acid (EPA) accounted for over 60% of total fatty acids in the batch tube culture, with EPA content increasing to a maximum after three days. In chemostat cultures, run at dilution rates of 0.15 day⁻¹ (0.45 of μ_max) and 0.3 day⁻¹ (0.9 of μ_max), cell concentration reached a steady state of 2.18 and 0.7 g/L, respectively, while contents of EPA per liter of culture at steady state were 100.9 and 82.5 mg/L, respectively. At both dilution rates, EPA content of total fatty acids was the same (35.0–35.2%). At a dilution rate of 0.3 day⁻¹, the continuous culture system manifested productivities of 0.51 g/L/d and 25.1 mg/L/d for biomass and EPA, respectively.     

Saturated fatty acid adsorption by acidified rice hull ash

Rice hull ash (RHA) was treated with 1.0 M HNO₃ (RHA-A1) and another batch was treated with 14.0 M HNO₃ (RHA-A14). RHA-A1 and RHA-A14 had a pH of 6.58 and 6.13, respectively. Adsorption of saturated fatty acids (C₈, C₁₀, C₁₂, C₁₄, C₁₆, and C₁₈) was carried out on RHA-A1 and RHA-A14 at 32±1°C. The adsorption data conformed to the Langmuir isotherm. The specific surface area of RHA-A1 was 183.84 m² g⁻¹ while that of RHA-A14 was 174.67 m² g⁻¹. The specific pore volume of RHA-A1 was 0.216 cm³ g⁻¹ while that of RHA-A14 was 0.234 cm³ g⁻¹. The acid-treated ash, RHA-A14 (q _m =0.43±0.03 mmol g⁻¹ where q _m is the amount of adsorbate adsorbed to form a monolayer coverage on the ash particles) showed a twofold increase in the adsorption of fatty acid per gram ash compared to RHA-A1 (q _m =0.25±0.03 mmol g⁻¹). The free energy of adsorption, ΔG° _ads, was determined to be −7.06±0.10 and −6.75±0.11 kcal mol⁻¹ for RHA-A1 and RHA-A14, respectively. The reduced ΔG° _ads values observed for RHA-A14 were attributed to the electrostatic repulsion of the hydrophobic chain of the fatty acid adsorbed on adjacent sites and brought into close proximity of each other. The ΔG° _ads values showed that the process of adsorption took place through physisorption on both RHA.     

Dynamics of Algal Secondary Metabolites in Two Species of Sea Hare

The function of acquired algal secondary metabolites in sea hares is the subject of debate, in part because the dynamics/processing of metabolites by sea hares is poorly understood. This study investigates the dynamics of red algal secondary metabolites in two sea hares, Aplysia parvula and Aplysia dactylomela. Secondary metabolite levels were quantified for the dietary red algae Laurencia obtusa and Delisea pulchra and for sea hares collected from these seaweeds in the field. The patterns and dynamics of algal secondary metabolites were further investigated in the laboratory by quantitative analysis of secondary metabolites in sea hares grown on diets of L. obtusa, D. pulchra, or the green alga Ulva sp. Sea hares accumulated the most abundant metabolites from each red alga, the terpene palisadin A from L. obtusa, and the halogenated furanone 3 from D. pulchra, and stored a greater proportion of these metabolites than other algal metabolites. A. parvula accumulated D. pulchra metabolites at much higher levels than L. obtusa metabolites. A. dactylomela accumulated similar concentrations of L. obtusa metabolites to A. parvula. The loss of L. obtusa metabolites by A. dactylomela matched that expected for dilution of metabolites via growth of the sea hares. However, the loss of L. obtusa metabolites by A. parvula was faster than predicted for growth alone, suggesting that metabolites were actively metabolized or excreted. Data for the loss of D. pulchra metabolites by A. parvula was equivocal. The secretions of A. parvula fed D. pulchra or L. obtusa were analyzed for the presence of algal secondary metabolites to investigate one possible path of excretion. L. obtusa secondary metabolites were detected in the mucous and opaline secretions of A. parvula, but D. pulchra metabolites were not detected in any secretions. The deployment of L. obtusa secondary metabolites in secretions by A. parvula may explain the more rapid rate of loss of these compounds and is consistent with a possible defensive role for acquired metabolites.     

The effect of short-term diets rich in fish, red meat, or white meat on thromboxane and prostacyclin synthesis in humans

Foods which increase tissue arachidonic acid levels have been proposed to increase thrombosis tendency, presumably through increased platelet aggregation. This study examined the effect of doubling the dietary arachidonic acid (20∶4n−6) using meat- or fish-based diets on the systemic production of prostacyclin (PGl₂) and thromboxane (TXA₂) in 29 healthy, nonsmoking adults. There were three, 3-wk low-fat dietary periods (<15% energy as fat) in which subjects consumed a vegetarian diet for 1 wk followed by 2 wk on diets containing meat or fish as sources of 20∶4n−6. Between each diet period, there was a 3-wk washout period, during which subjects returned to their normal diets. The level of 20∶4n−6 consumed during the last 2 wk of each study was approximately double the usual intake (mean 140 mg/d), while the mean eicosapentaenoic acid (20∶5n−3) content of the diets varied from 1 mg/d on the white meat diet to 70 mg/d on the red meat diet and to 847 mg/d on the fish diet. The serum phospholipid (PL) 20∶4n−6/20∶5n−3 ratios were 11∶1 on the vegetarian diet, 15∶1 on the white meat diet, 8∶1 on the red meat diet, and 2∶1 on the fish diet (P<0.001). Neither white nor red meat diets affected platelet 20∶4n−6 levels, platelet aggregation, ex vivo platelet TXB₂ production, or the systemic PGl₂ or TXA₂ production as measured by gas chromatography-mass spectrometry analysis of the excretion levels of the principal urinary metabolites 2,3-dinor-6-keto-PGF_1α (PGl₂-M) and 11-dehydro-TXB₂ (TXA₂-M), respectively. The fish diet decreased the 20∶4n−6/20∶5n−3 ratio in platelet PL from the baseline level of 45∶1 to 13∶1 (P<0.001), had no effects on platelet aggregation, but significantly decreased platelet TXB₂, production (collagen-stimulated) and TXA₂-M production, while PGl₂-M levels were unaltered. These results indicate that short-term diets which double the usual 20∶4n−6 intake using white meat (175–330 g/d) or red meat (275–530 g/d) are not associated with an increased TXA₂ production, but this does not rule out the adverse effects of 20∶4n−6 at higher levels in the diet, or for more prolonged periods. Short-term diets containing fish (100–200 g/d with 90–210 mg/d 20∶4n−6 and approximately 650–1000 mg/d 20∶5n−3) led to significant increases in platelet 20∶5n−3 levels and a decrease in the ex vivo and systemic TXA₂ production.     

Synthesis and characterization of aerogel-like mesoporous nickel oxide for electrochemical supercapacitors

Highly porous NiO was prepared via a combination of sol-gel process with supercritical drying method in this paper. The as-synthesized NiO samples exhibit 80–90% porosity and high surface area, ie, 180.5–325.6 m²g⁻¹. Cyclic voltammetric and chronopotentiometric measurements indicated the aerogel-like NiO in 1 mol.L⁻¹ KOH solution to behave capacitive well due to its uniform mesoporous microstructure. It was also observed that post-heating temperature plays a critical role in the mesoporous nature of the aerogel-like materials. An optimal heating temperature of 300^∘C was found to favor the formation of mesopores, which account for the large specific capacitance of as high as 125 F.g⁻¹. The average specific capacitance of the aerogel-like NiO was observed to be about 75–125 F.g⁻¹ between a potential window of 0–0.35 V vs. SCE.     

A simple unstructured model-based control for efficient expression of recombinant porcine insulin precursor by Pichia pastoris

Based on the fact that Pichia cell growth follows a Monod equation under the condition of methanol concentration limitation, a kinetics model of recombinant methylotrophic yeast Pichia pastoris expressing porcine insulin precursor (PIP) was developed in the quasi-steady state in the induction phase. The model revealed that the relationship between specific growth rate (μ) and substrate methanol concentration was in accord with the Monod equation. The fermentation kinetic parameters maximum specific growth rate (μ _max ), saturation constant (K _s ) and maintenance coefficient (M) were estimated to be 0.101 h⁻¹, 0.252 g l ⁻¹, and 0.011 g MeOH g⁻¹ DCW h⁻¹, respectively. The unstructured model was validated in methanol induction phase with different initial cell densities. Results showed that the maximum specific protein production rate (q _p.max ) of 0.098 mg g⁻¹ DCW h⁻¹ was achieved when μ was kept at 0.016 h⁻¹, and the maximum yield of PIP reached 0.97 g l ⁻¹, which was 1.5-fold as that of the control. Therefore, the simple Monod model proposed has proven to be a robust control system for recombinant porcine insulin precursor production by P. pastoris on pilot scale, which would be further applied on production scale. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

Characterizations of composite cathodes with La0.6Sr0.4Co0.2Fe0.8O3?δ and Ce0.9Gd0.1O1.95 for solid oxide fuel cells

Composite cathodes with La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) and Ce_0.9Gd_0.1O_1.95 (GDC) are investigated to assess for solid oxide fuel cell (SOFC) applications at relatively low operating temperatures (650–800 °C). LSCF with a high surface area of 55 m²g⁻¹ is synthesized via a complex method involving inorganic nano-dispersants. The fuel cell performances of anode-supported SOFCs are characterized as a function of compositions of GDC with a surface area of 5 m²g⁻¹. The SOFCs consist of the following: LSCF-GDC composites as a cathode, GDC as an interlayer, yttrium stabilized zirconia (YSZ) as an electrolyte, Ni-YSZ (50: 50 wt%) as an anode functional layer, and Ni-YSZ (50: 50 wt%) for support. The cathodes are prepared for 6LSCF-4GDC (60: 40 wt%), 5LSCF-5GDC (50: 50 wt%), and 4LSCF-6GDC (40: 60 wt%). The 5LSCF-5GDC cathode shows 1.29 Wcm⁻², 0.97 Wcm⁻², and 0.47 Wcm⁻² at 780 °C, 730 °C, and 680 °C, respectively. The 6LSCF-4GDC shows 0.92 Wcm⁻², 0.71 Wcm⁻², and 0.54 Wcm⁻² at 780 °C, 730 °C, and 680 °C, respectively. At 780 °C, the highest fuel cell performance is achieved by the 5LSCF-5GDC, while at 680 °C the 6LSCF-4GDC shows the highest performance. The best composition of the porous composite cathodes with LSCF (55 m²g⁻¹) and GDC (5 m²g⁻¹) needs to be considered with a function of temperature.     

Soil nitrogen conservation with continuous no-till management

Tillage management is an important regulator of organic matter decomposition and N mineralization in agroecosystems. Tillage has resulted in the loss of considerable organic N from surface soils. There is potential to rebuild and conserve substantial amounts of soil N where no-till management is implemented in crop production systems. The objectives of our research were to measure N conservation rate with continuous no-till management of grain cropping systems and evaluate its impact on mineralizable and inorganic soil N. Samples were collected from 63 sites in production fields using a rotation of corn (Zea mays L.)—wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.)—double-crop soybean (Glysine max L.) across three soil series [Bojac (Coarse-loamy, mixed, semiactive, thermic Typic Hapludults), Altavista (Fine-loamy, mixed semiactive, thermic Aquic Hapludults), and Kempsville (Fine-loamy, siliceous, subactive, thermic Typic Hapludults)] with a history of continuous no-till that ranged from 0 to 14 yrs. Thirty-two of the sites had a history of biosolids application. Soil cores were collected at each site from 0–2.5, 2.5–7.5 and 7.5–15 cm and analyzed for total N, Illinois soil N test-N (ISNT-N), and [NH₄ + NO₃]-N. A history of biosolids application increased the concentration of total soil N by 154 ± 66.8 mg N kg⁻¹ (310 ± 140 kg N ha⁻¹) but did not increase ISNT-N in the surface 0 – 15 cm. Continuous no-till increased the concentration of total soil N by 9.98 mg N kg⁻¹ year⁻¹ (22.2 ± 21.2 kg N ha⁻¹ year⁻¹) and ISNT-N by 1.68 mg N kg⁻¹ year⁻¹ in the surface 0–15 cm. The implementation of continuous no-till management in this cropping system has resulted in conservation of soil N.

Effects of surface area on electrochemical performance of Li[Ni<Subscript>0.2</Subscript>Li<Subscript>0.2</Subscript>Mn<Subscript>0.6</Subscript>]O<Subscript>2</Subscript> cathode material

The effect of surface area on the electrochemical properties and thermal stability of Li[Ni_0.2Li_0.2Mn_0.6]O₂ powders was characterized using a charge/discharge cycler and DSC (Differential Scanning Calorimeter). The surface area of the samples was successfully controlled from ~4.0 to ~11.7 m² g⁻¹ by changing the molar ratio of the nitrate/acetate sources and adding an organic solvent such as acetic acid or glucose. The discharge capacity and rate capability was almost linearly increased with increase in surface area of the sample powder. A sample with a large surface area of 9.6–11.7 m² g⁻¹ delivered a high discharge capacity of ~250 mAh g⁻¹ at a 0.2 C rate and maintained 62–63% of its capacity at a 6 C rate versus a 0.2 C rate. According to the DSC analysis, heat generation by thermal reaction between the charged electrode and electrolyte was not critically dependent on the surface area. Instead, it was closely related to the type of organic solvent employed in the fabrication process of the powder.