N2 Air Research Articles

174 OXIDATIVE STRESS AND LIPID PEROXIDATION IN BOVINE IN VITRO-PRODUCED EMBRYOS WITH DIFFERENT DEVELOPMENTAL SPEEDS

In vitro-produced embryos are less viable than their in vivo counterparts. It is known that the developmental speed is a reliable marker of embryo viability. One of the major factors impairing in vitro embryo development is oxidative stress. The aim of the study was to evaluate oxidative stress and lipid peroxidation in bovine in vitro-produced embryos that reached different developmental stages at the end of culture. Abattoir-derived oocytes were matured in vitro in TCM-199 with 15% bovine serum, 0.5 μg mL–1 of FSH, 5 μg mL–1 of LH, 0.8 mM L-glutamine and 50 mg mL–1 of gentamicin. Mature cumulus–oocyte complexes (COC) were fertilized in Tyrode's modified medium, supplemented by 5.3 SI mL–1 of heparin, 30 μM penicillamine, 15 μM hypotaurine, 1 μM epinephrine and 1% of bovine serum. Both in vitro maturation and IVF were carried out at 39°C and 5% CO2 in air. After 20 to 22 h of gamete co-incubation, presumptive zygotes were denuded and cultured in SOF for 7 days at 39°C under humidified air with 5% CO2, 7% O2 and 88% N2 in air. At the end of culture, embryos were assessed according to the stage of development as tight morulae (TM), early blastocysts (eBl), blastocysts (Bl), expanded blastocysts (XBl) and hatched blastocysts (HBl). For each stage of development, an average of 20 embryos were used to determine manganese superoxide dismutase (MnSOD) activity and levels of nitric oxide (NO2–) and thiobarbituric acid-reactive substances (TBARS). The SOD activity was determined by a colourimetric method (Caraglia M et al. 2011 Cell Death Dis. 2, 150, doi:10.1038/cddis.2011.34) whereas NO2– and TBARS were measured by a spectrophotometric method (Balestrieri et al. 2011 J. Cell. Physiol. doi:10.1002/jcp.22874). Data were analysed by t-test. Greater (P < 0.05) MnSOD activity was observed in faster developing embryos (i.e. XBl and HBl) compared with slower ones (i.e. TM, eBl and Bl; 0.46 ± 0.04, 0.46 ± 0.03, 0.14 ± 0.01, 1.66 ± 0.01 and 3.26 ± 0.3 U μg–1 of protein, in TM, eBl, Bl, XBl and HBl, respectively). At the same time, XBl and HBl showed the lowest NO2– levels. However, NO2– values were lower in TM compared with eBl and Bl (0.04 ± 0.002, 0.07 ± 0.005, 0.06 ± 0.003, 0.01 ± 0.002 and 0.01 ± 0.001 nM μg–1 of protein, in TM, eBl, Bl, XBl and HBl, respectively). Similarly to NO2–, TBARS levels were lower in XBl and HBl compared with the other stages (0.0059 ± 0.002, 0.009 ± 0.003, 0.006 ± 0.002, 0.001 ± 0.0001 and 0.0009 ± 0.0002 μM μg–1 of protein, in TM, eBl, Bl, XBl and HBl, respectively). In conclusion, these results clearly indicate developmental stage-dependent changes in MnSOD activity and levels of NO2– and TBARS, suggesting that oxidative stress and lipid peroxidation are reduced in faster developing embryos.

Study on the Characteristics of Emissions from Light Duty Vehicle Fueled with Biodiesel under Transient Operating Mode

Biodiesel is a renewable and clean alternative fuel. The exhausts emissions from light duty vehicle fueled with biodiesel and No.0 diesel fuel are measured and analyzed. The modular features of emissions under transient operating mode is investigated on. As compared to No.0 diesel fuel, experimental results show that the HC and CO emissions of cold start are improved much from light duty vehicle fueled with biodiesel and also the specific emissions of HC, CO and PM decrease 62.0%, 42.5% and 46.2% respectively, but the NOx specific emission rise 7.1% up. Chemical energy is released during the combustion of fuel, which produced CO2 and H2O, at the same time the N2 in air would also be oxygenated to NOx. So the concentration rate of NOx/CO2 is used to describe the regularity of NOx emission with the transient operating mode.

Laser direct joining of carbon fibre reinforced plastic tostainless steel

This study was performed to evaluate the characteristics and strengthsof dissimilar joints between carbon fibre reinforced plastics (CFRP)and stainless steel using high brightness continuous wave disc laser. Tensileshear tests demonstrated that strong CFRP steel joint with ∼4800 N couldbe produced. The joints were tightly bonded on atomic or molecular sized levelthrough Cr–Fe oxide film on the metal surface, and small fragments oftype 304 steel were detected on the fractured CFRP. Many bubbles of submillimetresize were formed all over the plastic melted zone in the CFRP. The gas compositionsinside the bubbles were H2 and hydrocarbon series as pyrolysisgases of the CFRP as well as N2 in air. These results suggest strongchemical and physical bonding of the CFRP on the oxide film of the type 304plate. Consequently, it was confirmed that a strong joint could be producedbetween CFRP and type 304 stainless steel with a laser beam.

A Bondable Metallization Stack That Prevents Diffusion of Oxygen and Gold into Monolithically Integrated Circuits Operating Above 500°C

We investigate use of tantalum silicide (TaSi2, 400 nm)/platinum (Pt, 200 nm)/iridium (Ir, 200 nm)/platinum (Pt, 200 nm) as both a bond metal and a diffusion barrier to prevent oxygen (from air) and gold (from the wire bond) from infiltrating silicon carbide (SiC) monolithically integrated circuits operating above 500°C for over 1000 h in air. The TaSi2/Pt/Ir/Pt metallization is easily bonded for electrical connection to off-chip circuitry and does not require extra anneals or masking steps. It can be used directly on ohmic contact metals, dielectric insulating layers, or interconnect metal, because it adheres to silicon dioxide (SiO2), silicon nitride (Si3N4), and titanium (Ti). In this study, we investigate use of the new metallization of TaSi2/Pt/Ir/Pt (in deposition order) with TaSi2 resting on top of a Ti-SiC contact annealed at 600°C for 30 min in nitrogen, which allows the TaSi2 layer to react with the bottom platinum layer to form the Pt2Si diffusion barrier at the Pt-Ir interface. Since the iridium layer does not readily form a silicide, it prevents the silicon from migrating into the topmost platinum layer during further annealing or high-temperature integrated circuit operation. This leaves a pure platinum layer at the surface, ideal for gold wire bonding. We discuss the characteristics of the TaSi2/Pt/Ir/Pt metallization at 500°C after 10 h, 100 h, and 1000 h in air ambient and N2 ambient. Auger electron spectroscopy (AES) depth profiles of the metallization and field-emission scanning electron microscopy-focused ion beam (FESEM-FIB) cross-sections are also discussed.

Novel BaCe 0.7In 0.2Yb 0.1O 3-δ proton conductor as electrolyte for intermediate-temperature SOFCs

The novel proton conductor BaCe0.7In0.2Yb0.1O3-δ (BCIYb) has been successfully synthesized by a modified Pechini method, and characterized as an electrolyte for intermediate-temperature solid oxide fuel cells. Acceptable tolerance to wet CO2 environment was found during chemical stability tests. No interaction between the BCIYb electrolyte and the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode was observed during the cathode fabrication process. Further, no detectable impurity phase was found when the BCIYb—LSCF mixed powders were calcined at 700°C for 50 h. BCIYb dense samples sintered at 1450°C for 5 h showed acceptable conductivities of 7.2 × 10−3, 8 × 10−3, 4.5 × 10−3 and 3.1 × 10−3 S/cm at 800°C in dry air, wet air, wet H2 and wet N2, respectively. The maximum cell power outputs of single cells with the configuration of Ni—BaZr0.1Ce0.7Y0.2O3-δ (BZCY)|BCIYb|BZCY—LSCF were 0.15, 0.218 and 0.28 W/cm2 at 600, 650 and 700°C, respectively. No cell degradation was observed for cells operated at a constant voltage of 0.7 V in the 25 h short-term durability test.

Modelling of microbial carbon and nitrogen turnover in soil with special emphasis on N-trace gases emission

We present a new model unifying state-of-the-art descriptions of microbial processes for denitrification, nitrification and decomposition of soil organic matter. The model is of medium complexity, filling a gap between simplistic model approaches with low predictive power and complex models, which are difficult to verify experimentally. The model Microbial Carbon and Nitrogen Turnover in soils (MiCNiT) is written in Ansi C++ and embedded into a modelling framework (MoBiLE) that provides initial conditions and accompanying ecosystem processes such as N uptake by plants, litterfall, soil water and soil temperature with established model approaches. The MiCNiT model explicitly calculates decomposition, dynamics of microbial biomass, denitrification, autotrophic and heterotrophic nitrification, applying the microbial activity concept, as well as transport of gases and solutes between anaerobic and aerobic soil fractions and through the soil profile. The model was tested against N2O and CO2 emission as well as C and N pool data from the Hoglwald Forest, Germany. Due to a detailed description of the soil biochemistry and gaseous transfers, MiCNiT is capable of simulating soil air NO, N2O and N2 concentrations and the net exchange of these gases at the soil-atmosphere interface, including a possible net uptake of N2O by soils.

Fatigue Threshold R-Curve Behavior of Grain Bridging Ceramics: Role of Grain Size and Grain-Boundary Adhesion

To better understand the role of grain size and grain-boundary adhesion on the fatigue threshold R-curve behavior of grain bridging ceramics, a study was conducted on the fatigue threshold behavior of 99.5% pure polycrystalline alumina with two different microstructures (fine and coarse) and in two different environments (moist air and dry N2). The fine-grained microstructure showed higher fatigue thresholds at short crack sizes, while the coarse-grained microstructure demonstrated higher fatigue thresholds at long crack sizes. The former effect lead to slightly higher calculated fatigue strengths and was attributed to the crack stalling process that leads to earlier elastic bridge formation in that microstructure. The latter effect is attributed to toughening that is dominated by frictional and mechanical interlocking bridges at longer crack sizes where the larger grains are able to give more bridging. By testing the coarse microstructure in a dry environment, a higher K0 was achieved for the glassy grain boundaries giving a higher R-curve at short crack sizes and higher calculated fatigue strengths.

Anthropogenic imprints on nitrogen and oxygen isotopic composition of precipitation nitrate in a nitrogen-polluted city in southern China

Abstract. Nitric acid (HNO3) or nitrate (NO3−) is the dominant sink for reactive nitrogen oxides (NOx = NO + NO2) in the atmosphere. In many Chinese cities, HNO3 is becoming a significant contributor to acid deposition. In the present study, we measured nitrogen (N) and oxygen (O) isotopic composition of NO3− in 113 precipitation samples collected from Guangzhou City in southern China over a two-year period (2008 and 2009). We attempted to better understand the spatial and seasonal variability of atmospheric NOx sources and the NO3− formation pathways in this N-polluted city in the Pearl River Delta region. The δ15N values of NO3− (versus air N2) ranged from −4.9 to +10.1‰, and averaged +3.9‰ in 2008 and +3.3‰ in 2009. Positive δ15N values were observed throughout the year, indicating the anthropogenic contribution of NOx emissions, particularly from coal combustion. Different seasonal patterns of δ15N-NO3− were observed between 2008 and 2009, which might reflect different human activities associated with the global financial crisis and the intensive preparations for the 16th Asian Games. Nitrate δ18O values (versus Vienna Standard Mean Ocean Water) varied from +33.4 to +86.5‰ (average +65.0‰ and +67.0‰ in 2008 and 2009, respectively), a range being lower than those reported for high latitude and polar areas. Sixteen percent of δ18O values was observed lower than the expected minimum of +55‰ at our study site. This was likely caused by the reaction of NO with peroxy radicals; peroxy radicals can compete with O3 to convert NO to NO2, thereby donate O atoms with much lower δ18O value than that of O3 to atmospheric NO3−. Our results highlight that the influence of human activities on atmospheric chemistry can be recorded by the N and O isotopic composition of atmospheric NO3− in a N-polluted city.

125 EFFECT OF GLYCERALDEHYDE-3-PHOSPHATE DURING BOVINE IN VITRO EMBRYO CULTURE

Most systems for producing mammalian embryos in vitro use glucose as an energy source in the media despite putative toxic effects (Schini and Bavister 1988 Biol. Reprod. 39, 1183–1192; Takahashi and First 1992 Theriogenology 37, 963–978). Currently there is a tendency to identify other suitable energy sources in an attempt to replace glucose from culture media. Glyceraldehyde-3-phosphate (G3P), a glucose-derived high-energy compound, is the end product of the energy-consuming phase of glycolysis that enters the pay-off phase of the pathway characterised by a net gain of energy. The aim of this study was to determine whether G3P is a valid energy source for supporting in vitro embryo development in cattle. Abattoir-derived oocytes (n = 832, over 4 replicates) were matured in vitro in TCM-199 with 15% bovine serum (BS), 0.5 μg mL–1 FSH, 5 μg mL–1 LH, 0.8 mM L-glutamine, and 50 mg mL–1 gentamicin. Mature COC were fertilized in Tyrode’s modified medium, with 30 mg mL–1 heparin, 30 mM penicillamine, 15 mM hypotaurine, 0.15 mM epinephrine, and 1% BS. Both IVM and IVF were carried out at 39°C and 5% CO2 in air. After 20 to 22 h of gamete co-incubation, presumptive zygotes were denuded and cultured in SOF containing either 1.5 mM glucose (control group) or G3P at 3 different concentrations (0.125, 0.5, and 1.5 mM). It is worth specifying that in the 3 G3P-supplemented groups small amounts of glucose were left (0.15 mM) because it is known that a complete removal would affect embryo development by interfering with ribose synthesis through the pentose–phosphate pathway. In vitro culture was carried out at 39°C under humidified air with 5% CO2, 7% O2, and 88% N2 in air for 7 days, when the percentages of tight morulae-blastocysts (TMBL) and superior quality blastocysts (BL) were recorded. Differences in embryo yields among groups were analysed by chi-square test. Supplementation of IVC medium with 1.5 mM G3P reduced (P < 0.01) TMBL (5.0%) and BL (5.0%) rates compared with all other groups, indicating a toxic effect. However, when G3P was added at lower concentrations, no differences in TMBL (37.3 and 26.1, respectively, with 0.125 and 0.5 mM G3P) and in BL rates (35.3 and 25.5%, respectively, with 0.125 and 0.5 mM G3P) were observed compared with the control (32.7% TMBL and 31.4% BL, respectively). Within G3P-treated groups, the higher embryo yields were recorded with 0.125 mM compared with 0.5 mM (P < 0.05) and 1.5 mM (P < 0.01). Interestingly, embryos produced with G3P at the lower concentrations (0.125 and 0.5 mM) seemed to show a faster development compared with the control. In conclusion, these results demonstrated that G3P is a valid energy source for bovine preimplantation embryos and, hence, that G3P supplementation of IVC medium may be a suitable option for reducing glucose concentration in the media. However, further studies are needed to investigate lower concentrations of G3P and to better evaluate embryo viability.

Development of Interspecies Somatic Cell Nuclear Transfer Embryos Reconstructed from Bactrian Camel (Camelus bactrianus) Fibroblasts and Dromedary Camel (Camelus dromedarius) Ooplasm.

Interspecies somatic cell nucleus transfer could not only be a useful bioassay system for assessing the ability of mammalian somatic cells to develop into embryos but can also be used as a possible approach to conserve endangered species. It could provide a useful technique to preserve the wild Bactrian camels, which are threatened with extinction. In the present study embryos were reconstructed by using skin fibroblast cells from a Bactrian camel (Camelus bactrianus) as donor karyoplasts and dromedary camel (Camelus dromedarius) oocytes as recipient cytoplasts for investigating the developmental potential of the these embryos. Mature oocytes were collected from super-stimulated dromedary camels by ultrasound guided transvaginal ovum pick-up, 26 h after GnRH administration. Serum-starved adult Bactrian camel skin fibroblast cells were injected in to the perivitalline space of enucleated dromedary oocytes. The fibroblast cells and recipient cytoplasm were fused by two DC pulses of 100 V/cm for 15 μs each using an Eppendorf electroporator at room temperature. Reconstructs were activated 1 h postfusion with 5μM ionomycine followed by exposure to 6-dimethylaminopurine for 4 h. The activated oocytes were then transferred to 500 μL of embryo culture medium I (modified potassium simplex optimization medium with essential and non-essential amino acids [KSOMaa] supplemented with 1% BSA) and cultured at 38.5°C in an atmosphere of 5% CO2, 5% O2, and 90% N2 in air. On Day 3 (Day 0 = day of activation) the cleaved embryos were transferred into 500μL of embryo culture medium II (modified KSOMaa supplemented with 10% FCS) and cultured under the same conditions until Day 7. The proportion of oocytes that cleaved was recorded on Day 3, and those that reached morula and blastocyst stages were recorded on Day 7 of culture. The embryos reconstructed from dromedary camel (Camelus dromedarius) fibroblasts and oocytes were treated in similar manner and worked as control. Out of 58 reconstructed embryos, in 3 replicates, 77.4 ± 2.1 couplets fused successfully and were cultured after activation. The embryos that cleaved (59.1 ± 5.7) and those developed to the blastocyst stage (34.4 ± 3.9) were not different from the control group. This study demonstrated, for the first time, that somatic cells from Bactrian camel can be reprogrammed in the dromedary camel ooplasm and such interspecies nuclear transfer embryos can develop to the blastocyst stage. Further studies are needed to see the feasibility of transferring these embryos into dromedary camel recipients and the possibility of producing Bactrian camel calves from dromedary recipient camels. (platform)

Excitational energy transfer enhancing ionization and spatial-temporal evolution of air breakdown with UV laser radiation

This paper examines the role multiphoton excitation of oxygen has on the ionization of nitrogen in laser air breakdown. Plasma is created by focusing a 193 nm ArF excimer laser using an 18 cm focal length lens, producing a cylindrical 540 μm wide spot of intensity 6.5 GW/cm2, well below the classical limit for collisional cascade (CC) breakdown. By spectroscopically monitoring the B Σ2u+ to X Σ2g+ transition at 391.4 nm of N2+ in N2 and O2 mixes, collisions between N2 and metastable O2 states that have undergone 1+1 absorption processes are shown to lower the degree of nonlinearity (i.e., the number of photons involved in the rate limiting multiphoton absorption process) in the ionization of N2. This process is also found to dominate the 2+1 resonant enhanced multiphoton ionization of N2 in air and be the primary source for ionization of N2 to the B Σ2u+ state. Plasma formation and evolution is also examined using a 1.3 cm focal length objective lens creating a 40 μm wide spot of intensity 1.25 TW/cm2, above the classical limit for breakdown. This plasma is imaged with a fast (1.2 ns) gating intensified charge coupled device camera. Early plasma formation is seen to be inhomogeneous in nature, and significant ion density is found to exist up to 20 μs after the laser pulse.

Evaluating source, chemistry and climate change based upon the isotopic composition of nitrate in ice cores

A clear negative trend is found in the nitrogen isotopic ratios (15N/14N) of nitrate over the industrial period, based on a 100-meter ice core from Summit, Greenland. This record indicates that isotopic composition of ice core nitrate reflects changes in nitrogen oxide (NOx) source emissions and that post-industrial emissions of NOx have resulted in a 12‰ (vs. air N2) decline in δ15N of atmospheric nitrate over the last ~300 years. Interestingly, over the last glacial period (as recorded in the Greenland GISP2 ice core), the δ15N of nitrate changes by ~20‰ from a typical pre-industrial Holocene value of 10‰ to a mean glacial value of 28‰, despite the lack of a significant change in nitrate concentration. The more recent ice core record clearly indicates an influence of NOx emission sources, therefore suggesting that the glacial-interglacial change in δ15N may be a record of significant variations in the contribution of NOx sources, such as lightning, biomass burning, biogenic soil emissions and oxidation of nitrous oxide in the stratosphere. In contrast to the source changes recorded by the nitrogen isotopes, the oxygen isotopic record of atmospheric nitrate (18O/16O, 17O/16O) in ice cores has implications for reconstruction of past atmospheric oxidant levels. This is because the oxygen isotopic composition of nitrate reflects oxidation of NOx to nitrate in the atmosphere by oxidants such as ozone and hydroxy and peroxy radicals. Measurements of variations in the isotopic composition of atmospheric nitrate inferred from ice cores could be used to improve interpretation of other records of δ15N such as those from tree rings and/or sediments.

Isotopic composition of nitrate in wet and dry atmospheric deposition on Crete in the eastern Mediterranean Sea

The eastern Mediterranean Sea (EMS) is a nutrient‐poor ocean with unusually high nitrate‐phosphate ratios (up to 28:1) and relatively depleted 15N/14N ratios (expressed as δ15N) in deepwater nitrate (δ15NO3− of 2.5‰) and sediments (<3.5‰) that have been attributed to extensive N2 fixation. To quantify the role of atmospheric NO3− deposition in the N cycle in the EMS, we analyzed NO3− and its δ15N in samples of dry and wet deposition on biweekly and per event basis from April 2006 to September 2007 on the island of Crete. Both dry and wet deposition samples have consistently negative δ15N compared to air N2, implying a strongly depleted atmospheric source calculated to be (weighted annual estimate) −3.1‰. The low δ15N of wet deposition is in agreement with data from other environments, but the consistently depleted nature of dry deposition is unusual and supports the view of an origin from association of atmospheric NO3− mainly with dust and sea salt. This situation is due to high levels of sulphate compared to ammonium, sea salt, and lithogenic material. Mass balance and isotope‐mixing calculations show that the present‐day inputs of nitrate from external sources into the surface water layer of the eastern Mediterranean Sea have a weighted mean δ15N‐NO3− of 0.5‰ to 1.5‰ and that particle flux to and mineralization in the deepwater pool over the last 40–50 years can account for the unusually low δ15N ratios found in deepwater NO3− without the need of any significant N2 fixation.

Photochemical Removal of N2O in N2 or Air Using 172 nm Excimer Lamps

N2O removal was investigated in N2 or air using 172 nm Xe2 excimer lamps (50 or 300 mW/cm2) without using any expensive catalysts. The residual amount of N2O and the formation ratios of products were measured as functions of photoirradiation time, N2O concentration, and O2 concentration. N2O (100 ppm) was completely converted to N2 and O2 without NOx emission in N2 at atmospheric pressure after 30 min photoirradiation using a high-power Xe2 excimer lamp (300 mW/cm2). 76% of N2O (100 ppm) was also converted to N2, O2, and HNO3 in air (20% O2) after 30 min photoirradiation using the high-power lamp. We concluded that N2O is dominantly decomposed by 172 nm photolysis in N2 and by the O(1D) + N2O reaction in air, where O(1D) atoms dominantly arise from the 172 nm photolysis of O2. The conversion of N2O in air increased more than twofold by decreasing the total pressure from atmospheric pressure to 20 kPa by suppressing the collisional quenching of O(1D) by N2 and O2 buffer gases. In a flow experiment, the conversion of N2O in N2 was only 6–18% in the total flow rate range of 0.1–1 L/min owing to the short residence time of N2O in the photolysis chamber.

Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane–air and ethylene–air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ∼8 × 1012 cm−3 (∼4.14 ppm) occurring at ∼250 µs after the pulse, with decay time of ∼16.5 ms. Peak NO atom mole fraction in a methane–air mixture with equivalence ratio of φ = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene–air mixture (also with equivalence ratio of φ = 0.5), the rise and decay times are comparable to air and methane–air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ∼20 ns and ∼1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (∼100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

Effects of H2O and carbonate ions on the hydrolysis of mechanochemically treated .BETA.-tricalcium bis(orthophosphate)

β-tricalcium bis(orthophosphate) [Ca3(PO4)2] (β-TCP) was mechanochemically treated with a mortar grinder in three different atmospheres of air, wet N2, and wet CO2. H2O and CO32- were incorporated into ground β-TCP, the amount of which depended on both the grinding time and the atmosphere. As the grinding time of β-TCP increased, it hydrolyzed easily to Ca-deficient hydroxyapatite. The apatite-formation ratio for β-TCP ground in wet CO2 was remarkably lower than that for β-TCP ground in air or wet N2. The role of H2O and CO32- in the hydrolysis of ground β-TCP was investigated by calorimetry together with spectroscopy. In calorimetry for each ground β-TCP, a strong exothermic band was observed, which was followed by a broad exothermic band. It is considered that the first band corresponds to the process of adsorption of H2O in the solvent onto the fresh surface of ground β-TCP and the second broad band corresponds to the apatite-formation process. With increasing amount of H2O incorporated into ground β-TCP, both the heat evolution of the first exothermic band and the apatite-formation ratio increased linearly. The H2O incorporated into ground β-TCP promotes the dissolution of β-TCP and apatite formation. In terms of the effect of the incorporated CO32- on hydrolysis, the incorporated CO32- prevents not only apatite formation but also the dissolution of β-TCP.

Free Volume Changes, Crystallization, and Crystal Transition Behavior of Syndiotactic Polystyrene in Supercritical CO2 Revealed by Positron Annihilation Lifetime Spectroscopy

The free volume of syndiotactic polystyrene (sPS) conditioned in supercritical CO2 was investigated by using positron annihilation lifetime spectroscopy (PALS). Supercritical CO2 increased the free volume cavity size of amorphous sPS and made the formation of γ crystal occur. The orthopositronium (o-Ps) intensity I3 was correlated well with the crystallinity of γ form sPS, revealed by its gradual decrease with the increase of crystallinity. Furthermore, the treatment atmosphere affected the crystallization behavior of amorphous sPS. The increased free volume cavity size of amorphous sPS treated in supercritical CO2 was larger than those treated in ambient air and supercritical N2. Among these treatment conditions, supercritical CO2 increased the free volume size of amorphous sPS more effectively and thus resulted in the formation of γ crystals. PALS measurements indicated that supercritical CO2 helped remaining a constant high free volume level of the amorphous parts of the semicrystalline sPS. Likely, the crystalline parts were also affected by the scCO2 as a transition from the γ form to the β form was revealed at high temperatures by WAXD.

Effect of quenching medium on photocatalytic activity of nano-TiO2 prepared by solvothermal method

Abstract Pure anatase nano-TiO2 powders were synthesized by solvothermal method using titanium butoxide as the precursor and were subjected to a rapid quenching in various media such as H2O, H2O2, air, and liquid N2 as a post-synthesis treatment. By creating a thermal shock effect, quenching process has shown to be an easy novel route for modifying surface defects of the nano-TiO2 and its photocatalytic activity. In this study, the TiO2 sample quenched in air at 77 K contained the highest amount of Ti3+ surface defect with the highest Ti3+/OH and was found to exhibit the highest photocatalytic activity for ethylene decomposition.

Catastrophic hurricane history revealed by organic geochemical proxies in coastal lake sediments: a case study of Lake Shelby, Alabama (USA)

We developed a new method for reconstructing millennia-long hurricane records from coastal environments that uses Organic Geochemical Proxies (OGPs) of organic carbon and nitrogen concentrations and their δ13C and δ15N compositions. The new method is independent of presence/absence of sand layers and improves significantly the severe-storm history resolution. The subject of this investigation is a 1.5 m long sediment core raised at 2.8 m water depth from the center of Lake Shelby, Alabama, a freshwater lake located approximately 250 m from the Gulf of Mexico, from which an overwash sand-layer based record was previously derived. The core contains two distinct sediment units; an upper 62 cm thick, fine-grained, organic-rich lacustrine sapropel (gyttja) that shows no visible structures except one sand lamina at 23.7 cm depth, and an underlying 90 cm thick, organic-poor lagoon/estuary clay unit. The sapropel unit was deposited over a 682 ± 30 cal year time interval (1320–2002 A.D.) with a mean sedimentation rate of 0.79 ± 0.04 mm/year. Lake Shelby’s water column exhibits two contrasting states based on water chemistry surveys (i) an “isolated”, stratified, mode under calm weather conditions with a relatively low trophic state, and (ii) a “flooded” mode occurring during storm surges when nutrient-rich seawater floods the lake. Statistically significant δ13C and δ15N positive excursions in organic matter, up to maximum values of −25 (‰ PDB) and 4 (‰ Air N2), respectively, are interpreted as geochemical responses to the marine intrusions that fertilize the lake, increase light availability, and cause eutrophication spikes. Detailed OGPs analyses crossing a sand layer that offers visual evidence of a catastrophic hurricane overwash event at 1717 A.D. exhibit large δ13C and δ15N positive shifts bounded by rapid returns to base values, thus confirming the validity of the hurricane identification by the OGPs model. Our data indicate that 11 catastrophic hurricanes hit the Alabama coast over the past 682 years with a rough recurrence interval of one in 62 years.

202 EFFECT OF OSTEOPONTIN ON IN VITRO EMBRYO DEVELOPMENT IN CATTLE

Osteopontin (OPN) is an acidic single-chain phosphorylated glycoprotein found both in the oviduct fluid (ODF) and oviductal epithelium in cattle, which is believed to facilitate fertilization. It was recently reported that addition of a rabbit polyclonal immunoglobulin G antibody against purified bovine milk OPN with sperm oocytes, bovine oocytes, or both decreased (P < 0.05) fertilization compared with the in vitro-fertilized control (Goncalves et al. 2007 Theriogenology 67, 468–74). The aim of the present work was to determine the effect of in vitro addition of OPN to the fertilization medium on both cleavage and postfertilization embryo development in cattle. In the first experiment, in vitro-matured oocytes were fertilized in modified TALP medium in the presence of 0.0, 0.1, 1.0, or 10 µg mL–1 of OPN. In a second experiment, matured oocytes were in vitro-fertilized in modified TALP medium in the presence of 0.0, 10, 20, or 40 µg mL–1 of OPN. In vitro fertilization was carried out with frozen–thawed spermatozoa from a bull previously tested for IVF. After 20 to 22 h of coincubation at 39�C, 5% in CO2 in air, presumptive zygotes were vortexed to remove cumulus cells, washed, and transferred, 30 to 50 per well, into 400 µL of SOF modified medium. Zygotes were incubated in a humidified mixture of 5% CO2, 7% O2, and 88% N2 in air at a temperature of 39�C. On Day 7 of development (Day 0 = day of insemination), cleavage and development rates into transferable embryos (TE)–tight morulae (TM) and blastocysts (Bl) of superior quality were recorded. Differences in the percentages of both cleavage and blastocyst rates among groups were analyzed by a chi-square test. In experiment 1, numerically higher percentages of TM–Bl (29.5, 29.5, 30.5, and 37.5%, respectively, in the control group and in the groups with 0.1, 1, and 10 µg mL–1 of OPN; P = 0.25) and Bl (28.6, 27.5, 29.1, and 36.7, respectively, in the control group and in the groups with 0.1, 1, and 10 µg mL–1 of OPN; P = 0.24) were observed with 10 µg mL–1 of OPN. In experiment 2, significantly more cleavage (80.0 v. 71.3%; P < 0.05) and higher percentages of TM–Bl (44.6 v. 34.5%; P < 0.05) and Bl (39.2 v. 30.6%; P = 0.06) were observed with 10 µg mL–1 of OPN v. the control. Combined analysis from both experiments showed an overall effect of 10 µg mL–1 of OPN v. the control in the percentages of TM–Bl and Bl (respectively, 41.1 v. 33.3% and 37.7 v. 30.5%; P < 0.05). These results indicate that it is possible to improve the efficiency of bovine in vitro embryo production by adding the oviductal protein OPN.