Form Of CH4 Research Articles

Effects of Liriope platyphylla and Organic Acids in Hanwoo Feed on Greenhouse Gas Reduction

Background: Liriope platyphylla and organic acids (humic and fulvic acids) as additives in the feedstock may aid in decreasing CH4 formation in the rumen. Based on previous studies, Hanwoo steers were raised with feedstock added with Liriope platyphylla and organic acids and their fecal samples were analyzed to determine the changes in their organic matter and nitrogen content determining the GHG emissions from feces in the form of CH4 and N2O. Methods: Ten Hanwoo cattle were provided with experimental diet and their weights were measured to determine harmful effects of experimental diet and measure fecal composition. To measure CH4 emission from the rumen in vitro, rumen fluid with Liriope platyphylla 1.0% and organic acids 0.05% added to the feed was prepared and incubated in triplicate. Result: The addition of Liriope platyphylla had a positive effect on immune function and blood composition, as well as CH4 reduction and further the addition of organic acids resulted in the lowering of CH4 emissions when compared with that of the control. The addition of Liriope platyphylla and organic acids is a potential additive of reducing CH4 emissions from ruminants without disrupting cattle growth.

Interfacial Layer Effect on the Adhesion of the Ultra-Hard Thick TAC Film Deposition

Carbon-based thin film tool coatings, such as diamond-like carbon (DLC), have excellent lowfriction and anti-sticking properties. These thin films are widely used for the cutting and machining of increasingly widely-used lightweight non-metallic and non-ferrous metal materials, as a part of countermeasures against global warming. However, non-metallic and non-ferrous metal materials are significantly inferior in strength and heat resistance compared to iron-based metals. Therefore, they are primarily employed in high-content fiber reinforced composite materials, which significantly improves their mechanical and thermal properties. Tetrahedral amorphous carbon (TAC) coating has a hardness level similar to diamond coating. However, when TAC is deposited as a thick film, delamination of the coating layer may occur because of the high internal compressive stress between the carbide-based substrate and coating layer, thereby restricting its scalability to other applications. Other factors to be controlled for thick film TAC deposition include minimizing droplets generated during the coating process, and improving interfacial properties like hardness and fatigue resistance. Here, C in the form of CH4, which has high solubility over Cr and forms various compounds, was added during the interfacial deposition process, between the carbide and TAC, to improve interfacial strength and adhesion by precipitation of carbide at the interface. This eventually led to thick TAC film with the thickness and adhesion of commercially viable thick film.

Estimasi Emisi Gas Rumah Kaca dari Proses Pengelolaan Sampah Di Tempat Pemrosesan Akhir (TPA) Kabupaten Kerinci

The amount of waste that enters the TPA of Kerinci Regency in 2020 is 21,962 Gg/year. The waste that enters the TPA is predicted to produce greenhouse gas emissions in the form of CH4, N2O and CO2. This study aims to determine the amount of generation and type of waste composition and calculate the estimated amount of greenhouse gas emissions (CH4, N2O, and CO2) in the TPA Kerinci until 2030. The calculation of GHG emissions used in this study is to use the Intergovernmental panel on climate change (IPCC) 2006. The composition of waste produced from TPA Kerinci Regency consists of 14.37% plastic waste, 15.50% Nappies waste, 2.47% textile waste, 1.86% metal waste, 2.98% wood waste, 39.93% food waste, 10.12% garden and plant waste, 7.46% paper and cardboard waste, 1.61% rubber and leather waste, 0.55% glass waste, and 3.11% other waste. In the waste management process, the emissions generated from the landfill zone, composting and heavy equipment produced in the TPA Kerinci Regency are 0.496 Gg CO2-eq, while in 2030 the resulting emissions will increase by 16.55 Gg CO2-eq. GHG emission estimation can be used to determine methods of mitigating greenhouse gas emissions.

Experimental Study on CO2 Methanation over Ni/Al2O3, Ru/Al2O3, and Ru-Ni/Al2O3 Catalysts

CO2 methanation is recognized as one of the best technologies for storing intermittent renewable energy in the form of CH4. In this study, CO2 methanation performance is investigated using Ni/Al2O3, Ru/Al2O3, and Ru-Ni/Al2O3 as the catalysts under conditions of atmospheric pressure, a molar ratio of H2/CO2 = 5, and a space velocity of 5835 h−1. For reaction temperatures ranging from 250 to 550 °C, it was found that the optimum reaction temperature is 400 °C for all catalysts studied. At this temperature, the maximum values of CO2 conversion, H2 efficiency, and CH4 yield and lowest CO yield can be obtained. With temperatures higher than 400 °C, reverse CO2 methanation results in CO2 conversion and CH4 yield decreases with increased temperature, while CO is formed due to reverse water-gas shift reaction. The experimental results showed that CO2 methanation performance at low temperatures can be enhanced greatly using the bimetallic Ru-Ni catalyst compared with the monometallic Ru or Ni catalyst. Under ascending-descending temperature changes between 250 °C and 550 °C, good thermal stability is obtained from Ru-Ni/Al2O3 catalyst. About a 3% decrease in CO2 conversion is found after three continuous cycles (74 h) test.

Conversion of methane and n-pentane over Pt-Sn/γ-Al2O3 systems under non-oxidative conditions

Monometallic catalysts Pt/Al2O3 and Sn/Al2O3 and bimetallic systems Pt—Sn/Al2O3 with the platinum and tin contents ∼0.51 and 0.13–0.38 wt.%, respectively, were synthesized. The introduction of tin into the Pt/Al2O3 catalyst decreases the electron deficiency and dispersion of platinum but exerts almost no effect on the concentration of the Lewis acid sites on the support surface. The degree of dehydrogenation of the activated forms of methane (CHx fragments) on the catalysts with tin additives is lower than that on the surface of the monometallic Pt/Al2O3 catalyst. The reactivity of the CHx species formed on the surface of the Pt—Sn/Al2O3 samples was studied in the co-conversion of the activated forms of CH4 with n-pentane to benzene and toluene under the non-oxidative conditions. The introduction of tin into the Pt/Al2O3 decreases the electron deficiency of platinum but does not decrease the yield of aromatic hydrocarbons. The modifying effect of tin appears as a decrease in the degree of dehydrogenation of the activated forms of methane, which results in an increase in the reactivity of activated methane during co-conversion with n-pentane.

Greenhouse gas emissions of rice straw return varies with return depth and soil type in paddy systems of Northeast China

ABSTRACT A two-year field experiment was performed to investigate greenhouse gas emissions from rice straw return to different return depths and soil types. The experiment comprised of six treatments: without straw return (silty clay loam, SC; sandy loam, SL); straw return to topsoil (SCT, SLT); and straw return to subsoil (SCS, SLS). SCT and SLT released 2402.18 and 2494.01 kg ha−1 more CO2 than SC and SL in total, respectively. Straw return to topsoil and subsoil in both soil textures significantly increased CH4 emissions. Compared to the total cumulative CH4 fluxes in SC and SL, those of SCT and SLT increased by 239.62 and 131.34 kg ha−1, and those of SCS and SLS increased by 125.07 and 89.93 kg ha−1, respectively. SCT and SCS emitted 389.06 and 168.94 g ha−1 less N2O than SC in total, respectively. SL released 146.28 and 72.06 g ha−1 more N2O than SLT and SLS in total, respectively. The variations in the ratio of the total cumulative fluxes of CO2 and CH4, indicate that rice straw return to silty clay loam and subsoil tend to release more carbon in the form of CH4 compared to sandy loam and topsoil, respectively.

Comprehensive assessments of carbon dynamics in an intermittently-irrigated rice paddy

Rice is a major crop that feeds more than half of the global population. Rice paddies play a complex role in the carbon cycle by emitting CH4 to the atmosphere while either sequestering or releasing CO2 to the atmosphere. Here, we present 3.5 years of eddy covariance measurements of CO2 and CH4 fluxes over an intermittently irrigated, single crop rice paddy in South Korea in tandem with carbon stock measurements for leaves, stems, grains, and roots. The rice paddy acted as a slight sink or neutral in CO2 (−47 ± 51 g C m−2y−1; mean ± 95% confidence interval) with 941 ± 130 g C m−2y−1 and 894 ± 108 g C m−2y−1 as the gross primary production (GPP) and ecosystem respiration (Reco), respectively. The mean annual net primary productivity (NPP) was 666 ± 31 g C m−2y−1, which was partitioned to leaves (9%), stems (30%), grains (51%), and roots (10%), for a harvest index of 57%. The paddy emitted 20.6 ± 1.5 g C m−2y−1 in the form of CH4, of which between 82 and 96% was emitted during the cultivation period (~132 days) . The CH4 flux showed a mid-season decline caused by mid-season drainage, which produced aerobic soil conditions that inhibited CH4 emissions. The proportion of estimated ebullitive flux to total CH4 flux ranged from 10 to 17% during the cultivation period. GPP, Reco, and CH4 fluxes varied by 12%, 11%, and 7%, respectively, over the 3-year period. When considering the harvest and the global warming potential of CH4, the paddy shifted from a greenhouse gas sink to a strong source (2,741 ± 468 g CO2 eq m−2y−1). These findings will improve our understanding of carbon budgets and cycles, and help develop greenhouse gas and water management strategies for rice paddies.

Inclusion of quebracho tannin extract in a high-roughage cattle diet alters digestibility, nitrogen balance, and energy partitioning.

Condensed tannins (CT) might improve animal and system-level efficiency due to enhanced protein efficiency and reduced CH4. This study evaluated the impact of quebracho tannin (QT) extract fed at 0%, 1.5%, 3%, and 4.5% of dry matter (DM), within a roughage-based diet on apparent digestibility of DM, organic matter (OM), fibrous fractions, and N retention and energy partitioning of growing steers (236 ± 16 kg BW). A Latin rectangle design with eight animals and four periods was used to determine the whole-animal exchange of CO2, O2, and CH4 as well as the collection of total feces and urine over a 48-h period, using two open-circuit, indirect calorimetry respiration chambers. Following the removal of steers from respiration chambers, rumen inoculum was collected to determine ruminal parameter, including volatile fatty acids (VFA) and ammonia. Animals were fed a 56.5% roughage diet at 1.7% BW (dry matter basis). Dry matter and gross energy intakes were influenced by the level of QT inclusion (P ≤ 0.036). Digestibility of DM, OM, and N was reduced with QT inclusion (P < 0.001), and fiber digestibility was slightly impacted (P > 0.123). QTs altered the N excretion route, average fecal N-to-total N ratio excreted increased 14%, and fecal N-to-urinary N ratio increased 38% (P < 0.001) without altering the retained N. Increased fecal energy with QT provision resulted in reduced dietary digestible energy (DE) concentration (Mcal/kg DM; P = 0.024). There were no differences in urinary energy (P = 0.491), but CH4 energy decreased drastically (P = 0.007) as QT inclusion increased. Total ruminal VFA concentration did not differ across treatments, but VFA concentration increased linearly with QT inclusion (P = 0.049). Metabolizable energy (ME) was not affected by the QT rate, and the conversion efficiency of DE-to-ME did not differ. Heat energy decreased (P = 0.013) with increased QT provision likely due to changes in the DE intake, but there was no difference in retained energy. There were no differences for retained energy or N per CO2 equivalent emission produced (P = 0.774 and 0.962, respectively), but improved efficiency for energy retention occurred for 3% QT. We concluded that QT provided up to 4.5% of dry matter intake (about 3.51% of CT, dry matter basis) does not affect N and energy retention within the current setting. Feeding QT reduced energy losses in the form of CH4 and heat, but the route of energy loss appears to be influenced by the rate of QT inclusion.

Reaction mechanism of the Me3AuPMe3-H2 plasma-enhanced ALD process.

The reaction mechanism of the recently reported Me3AuPMe3-H2 plasma gold ALD process was investigated using in situ characterization techniques in a pump-type ALD system. In situ RAIRS and in vacuo XPS measurements confirm that the CH3 and PMe3 ligands remain on the gold surface after chemisorption of the precursor, causing self-limiting adsorption. Remaining surface groups are removed by the H2 plasma in the form of CH4 and likely as PHxMey groups, allowing chemisorption of new precursor molecules during the next exposure. The decomposition behaviour of the Me3AuPMe3 precursor on a Au surface is also presented and linked to the stability of the precursor ligands that govern the self-limiting growth during ALD. Desorption of the CH3 ligands occurs at all substrate temperatures during evacuation to high vacuum, occurring faster at higher temperatures. The PMe3 ligand is found to be less stable on a gold surface at higher substrate temperatures and is accompanied by an increase in precusor decomposition on a gold surface, indicating that the temperature dependent stability of the precursor ligands is an important factor to ensure self-limiting precursor adsorption during ALD. Remarkably, precursor decomposition does not occur on a SiO2 surface, in situ transmission absorption infrared experiments indicate that nucleation on a SiO2 surface occurs on Si-OH groups. Finally, we comment on the use of different co-reactants during PE-ALD of Au and we report on different PE-ALD growth with the reported O2 plasma and H2O process in pump-type versus flow-type ALD systems.

Improving the efficiency of Chemical Looping Combustion with coal by using ring-type internals in the fuel reactor

Chemical Looping Combustion (CLC) with solid fuels has been widely developed by using two interconnected fluidized beds, the fuel reactor and the air reactor, with an oxygen carrier continuously circulating between them. Experience gained in this process shows that high CO2 capture values can be reached. However, complete combustion of the fuel is not achieved, with some H2, CO and CH4 as the main unconverted compounds in the combustion products from the fuel reactor. It is believed that the combustion efficiency can be increased by improving the gas-solid contact in the fuel reactor. In this work, the solids distribution in the fuel reactor was modified by using ring-type internals with the objective of enhancing the gas-solid contact. Two experimental campaigns were carried out in a 50 kWth CLC unit burning a bituminous coal with ilmenite particles in the temperature interval of 900–1000 °C. The first campaign was conducted with the original riser of the fuel reactor, which was characterized by a smooth section from bottom to top. For the second campaign, three ring-type internals were implemented in the riser in order to modify the solids distribution in the fuel reactor. The presence of the internals had a beneficial effect on the coal combustion. The major benefit was an improved oxidation of volatile matter in the form of CH4 and the full conversion of H2. As a result, the total oxygen demand decreased by 20%, from 12.2% to 9.8%, with the implementation of the internals.

Methane flux dynamics in a submerged aquatic vegetation zone in a subtropical lake

Submerged macrophytes are important primary producers for shallow lake systems. So far, their overall role in regulating lake methane flux is a subject of debate because the oxygen produced by their roots can promote methane oxidation in the sediment but they can also enhance methanogenesis through organic substrate production. In this study, we used the eddy covariance method to investigate the temporal dynamics of the CH4 flux in a habitat of submerged macrophytes in Lake Taihu. The results show that the nighttime CH4 flux is on average 33% higher than the daytime flux, although a clear diurnal pattern is evident only in the spring. At the daily to the seasonal time scale, the sediment temperature is the main driver of the CH4 flux variations, implying higher methane production in the sediment at higher temperatures. The annual CH4 emission (6.12 g C m−2 yr−1) is much higher than the published whole-lake mean flux (1.12 g C m−2 yr−1) and that reported previously in the eutrophic phytoplankton zone of the lake (1.35 g C m−2 yr−1), indicating that the net effect of the submerged macrophytes is to enhance methane emission. At the annual time scale, 3.5% of the carbon gained by the net ecosystem production is lost to the atmosphere in the form of CH4.

A partial life cycle assessment of the greenhouse gas mitigation potential of feeding 3-nitrooxypropanol and nitrate to cattle

Agricultural industries are faced with the challenge to reduce their emissions of greenhouse gases (GHG) such as nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4). Approximately 27% of the GHG emissions generated by agriculture and 80% of the GHG emissions generated by livestock are in the form of CH4 from enteric fermentation and manure management. Two feed additives that have been shown to decrease enteric CH4 emissions are 3-nitrooxypropanol (3-NOP) and nitrate. However, data are lacking on the net impact of these CH4 mitigating additives on whole farm GHG emissions across different production systems. The objectives of this partial life cycle assessment (LCA) were: 1) to analyse the effect of 3-NOP and nitrate on whole farm GHG emissions of Australian and Canadian beef and dairy farms, and 2) to analyse the effect of different strategies of 3-NOP and nitrate feeding on whole farm GHG emissions. Two Australian dairy farms (ADF), one Australian beef farm (ABF), one Canadian dairy farm (CDF) and one Canadian beef farm (CBF) were modelled over the productive lifespans of dairy and beef herds. Australian farm GHG emissions were estimated based on the Australian National Greenhouse Gas Inventory method using the Greenhouse Accounting Framework calculators for beef and dairy. For the Canadian farms, total GHG emissions were estimated using Holos 3.0.3, a whole-farm software model. For all farms, the system boundary of the partial LCA was defined as the farm gate, including emissions associated with on-farm activities and emissions associated with production and transport of major production inputs. Both additives decreased whole farm GHG emissions; however, 3-NOP had a greater effect than nitrate. Feeding 3-NOP but not nitrate could be economical for both beef and dairy farms, depending on the cost of 3-NOP. It is concluded that 3-NOP can make an important contribution to reducing whole farm GHG emissions; however, a carbon offset method would have to be in place to incentivize its use in the livestock industries.

Beavers affect carbon biogeochemistry: both short‐term and long‐term processes are involved

Abstract With the recent population increase in beavers (Castor spp.), a considerable amount of new riparian habitat has been created in the Holarctic. We evaluated how beaver‐induced floods affect carbon (C) dynamics in the beaver ponds and in the water‐atmosphere and riparian zone interfaces. Beaver disturbance affects soil organic C storage by decreasing or increasing it, resulting in a redistribution of C. Upon flooding, the concentration of dissolved organic carbon (DOC) increases in the water. This C can be released into the atmosphere, it can settle down to the bottom sediments, it can be sequestered by vegetation, or it can be transported downstream. The carbon dioxide (CO2) emissions vary between 0.14 and 11.2 g CO2 m−2 day−1, averaging 4.9 CO2 g m−2 day−1. The methane (CH4) emissions vary too, from 27 mg m−2 day−1 to 919 mg m−2 day−1, averaging 222 mg CH4 m−2 day−1. Globally, C emission from beaver ponds in the form of CH4 and CO2 may be 3.33–4.62 Tg (teragram, 1012 g) year−1. The yearly short‐term sedimentation rates in beaver ponds vary between 0.4 and 47 cm year−1, and individual ponds contain 9–6355 m3 of sediment. The approximate global estimate for yearly C sedimentation is 3.8 Tg C; beaver ponds globally contain 380 Tg sedimented C. After being formed, beaver pond deposits can remain for millennia. Both C sequestration and CO2 and CH4 emissions in ponds of various ages should be taken into account when considering the net effect of beavers on the C dynamics. With present estimates, beaver ponds globally range from a sink (−0.47 Tg year−1) to a source (0.82 Tg year−1) of C. More research is needed with continuous flux measurements and from ponds of different ages. Likewise, there is a need for more studies in Eurasia to understand the effect of beaver on C biogeochemistry.

Degassing of organic carbon during regional metamorphism of pelites, Wepawaug Schist, Connecticut, USA

A comprehensive understanding of the degassing systematics of organic carbon (OC) during regional metamorphism is necessary to evaluate the role that metamorphism plays in the global carbon cycle. In this study, weight percentages and δ13C values of OC were measured in 70 samples of metapelites from the Wepawaug Schist, Connecticut, where classic Barrovian metamorphism occurred and graphitic OC is widespread. Relative to low-grade chlorite + biotite zone rocks, our mass balance analysis shows that OC in the metapelites underwent progressive loss from −14% (−0.06 g OC per 100 g rock) in the garnet zone, through −21% (−0.09 g/100 g) in the staurolite zone, to −26% (−0.11 g/100 g) in the kyanite zone. The average δ13C values in different metamorphic zones (ranging from −14.74‰ to −16.24‰) are all much higher than normal organic material in marine sediments, and increase slightly from the chlorite + biotite zone to the garnet zone and decrease slightly at higher metamorphic grades. Organic carbon degassing in the form of CH4 during the late stage of diagenesis or in the earliest stages of metamorphism could produce this significant 13C enrichment. Under the assumption that the 13C enrichment is caused by graphite degassing during the lowest-grade metamorphism (chlorite zone or lower), the degassing profile of OC during the regional metamorphism is reconstructed by combining the δ13C and OC mass change data. The computed results indicate that graphitic OC in the Wepawaug Schist probably underwent considerable loss at lowest-grade metamorphic conditions, ranging from ~−40% to ~−90% (or from −0.23 g OC per 100 g rock to −2.8 g OC per 100 g rock), and remained relatively inert at higher grades. Based on the mass balance analysis, δ13C systematics, and exploratory modeling results, this study argues that the lowest-grade or pre-metamorphic stages would be the more efficient OC liberators, and that the degassing potential of OC in the major stages of Barrovian metamorphism appears to be much more restricted. Additional independent studies are required to decipher the early degassing of OC after the deposition of organic matter, which could in turn help better constrain the degassing of OC during regional metamorphism.

Bio-electrochemically assisting low-temperature anaerobic digestion of low-organic strength wastewater

This study provides a new approach by using bio-electrochemical systems (BES) to improve the performance of anaerobic digestion (AD) for treating low-organic strength wastewater and recovering energy in the form of CH4. The BES had a relatively higher capability for temperature shock. At an applied voltage of 0.4 V, the BES significantly enhanced both the chemical oxygen demand (COD) removal and CH4 yield efficiency compared with those of the control at operational temperatures of 20, 12, and 8 °C. Energy balance evaluation indicated that the net energy obtained from the BES was higher than the energy recovered from the control, suggesting that operation of BES was economically available. Analysis of microbial physiological characteristics elucidated that electrochemical effects stimulated the production of extracellular polymeric substances, suggesting a faster metabolic activity of biomass in the BES. 16S rRNA sequencing showed that genera of H2-utilizing methanogens, Methanobacterium, Methanoregula, and Methanospirillum, dominated the consortia at low temperatures. On the surfaces of cathodes, considerable enrichments of H2-producing bacteria, Acetobacteroides and Anaerolinea were observed, implying the formation of H2-mediated syntrophic communities in the BES. The combined results suggest that operation of BES for low-temperature AD of low-organic strength wastewater will be an attractively potential technology.

Two-stage co-fermentation of lipid-extracted microalgae waste with food waste leachate: A viable way to reduce the inhibitory effect of leftover organic solvent and recover additional energy

This study aimed to mitigate the inhibitory effect of leftover organic solvent (CH3Cl, chloroform) on anaerobic digestion of lipid-extracted microalgae waste (LEMW). Food waste leachate (FWL) was added as a co-substrate and a two-stage fermentation process (H2 production with acidogenesis + methanogenesis) was adopted. The result of the first batch experiment, conducted in the absence of chloroform, showed that as the FWL addition ratio increased up to 60% on chemical oxygen demand (COD) basis, there was a gradual increase in the amount of H2 produced. At 80% addition, however, there was a huge drop in H2 yield, accompanied by a drop in pH. In the presence of chloroform (100–900 mg CH3Cl/L), the mixture (LEMW:FWL = 40:60) exhibited a much higher tolerance than that of LEMW alone, which could be ascribed to the co-metabolic degradation of chloroform by FWL addition. At 600 and 900 mg CHCl3/L, the degradation efficiency dropped below 40% for LEMW alone, while it was maintained above 90% in the mixture. A H2 yield of 36 mL H2/g COD, equivalent to 2.6% of the energy content in the feedstock, was attained from the mixture at 600 mg CHCl3/L. The H2 fermented effluent was then fed to a continuous methanogenic reactor at HRT 40 d, and 82% of energy content in the feedstock was further gained in the form of CH4. Although the energy gained from H2 production was negligible, most of the chloroform was degraded during acidogenesis, which resulted in a successful CH4 conversion.

CO2 methanation of Ni catalysts supported on tetragonal ZrO2 doped with Ca2+ and Ni2+ ions

This paper reports highly active CO2 methanation catalysts of Ni supported on tetragonal ZrO2 for supply of renewable energy in the form of CH4 via electrolytic H2 generation. The Ni/tetragonal ZrO2 catalysts with the nominal cationic compositions of 50 at.% Ni-(Zr + Ca) (Ca/(Zr + Ca) molar ratios of 0.125–0.333), were prepared by calcination of a ZrO2 sol mixed with nickel and calcium nitrates at 650 and 800 °C and subsequent H2 reduction of NiO. All the catalysts prepared exhibited almost 100% CH4 selectivity, and the activity increased with the calcium content up to a Ca/(Zr + Ca) molar ratio between 0.167 and 0.200, above which the activity tended to decrease. At the optimized calcium content, a tetragonal ZrO2 phase with cation vacancies introduced by Ca2+ and Ni2+ doping was predominant, in addition to fcc Ni. A monoclinic ZrO2 phase was also present below the optimized calcium content, while a Ca-rich amorphous or CaZrO3 phase was formed with tetragonal ZrO2 above the optimized calcium content. The high catalytic activity of the catalyst with the optimized composition could be correlated with the presence of tetragonal ZrO2 with oxygen vacancies.

Concentration Behavior of Non-Metallic Impurities in Cu Rods Refined by Argon and Hydrogen Plasma-Arc Zone Melting

Removal of non-metallic impurities like O, N, C and S in 4N Cu rods by argon plasma-arc zone melting and hydrogen plasma-arc zone melting was investigated. The experimental results were discussed on the basis of thermodynamic estimation. Substantial removal of these impurities along the length of the Cu rods by argon plasma-arc zone melting was observed and relatively better removal by hydrogen plasma-arc zone melting was found to be due to activated hydrogen atoms. The removal of O, N, C and S was ascribed to the segregation effect as well as evaporation in the form of CH4, H2O and H2S. As a result, it was found that hydrogen plasma-arc zone melting is a better technique to eliminate non-metallic impurities like O, N, C and S in Cu.

Effect of Cattle Slurry Separation on Greenhouse Gas and Ammonia Emissions during Storage

Storage of cattle slurry leads to emissions of methane (CH(4)), nitrous oxide (N(2)O), ammonia (NH(3)), and carbon dioxide (CO(2)). On dairy farms, winter is the most critical period in terms of slurry storage due to cattle housing and slurry field application prohibition. Slurry treatment by separation results in reduced slurry dry matter content and has considerable potential to reduce gaseous emissions. Therefore, the efficiency of slurry separation in reducing gaseous emissions during winter storage was investigated in a laboratory study. Four slurry fractions were obtained: a solid and a liquid fraction by screw press separation (SPS) and a supernatant and a sediment fraction by chemically enhanced settling of the liquid fraction. Untreated slurry and the separated fractions were stored in plastic barrels for 48 d under winter conditions, and gaseous emissions were measured. Screw press separation resulted in an increase of CO(2) (650%) and N(2)O (1240%) emissions due to high releases observed from the solid fraction, but this increase was tempered by using the combined separation process (CSP). The CSP resulted in a reduction of CH(4) emissions ( approximately 50%), even though high emissions of CH(4) (46% of soluble C) were observed from the solid fraction during the first 6 d of storage. Screw press separation increased NH(3) emissions by 35%, but this was reduced to 15% using the CSP. During winter storage greenhouse gas emissions from all treatments were mainly in the form of CH(4) and were reduced by 30 and 40% using SPS and CSP, respectively.

Effect of Thermal Treatment on Carbon-Doped Silicon Oxide Low Dielectric Constant Materials

Carbon-doped silicon oxide (SiOCH) low dielectric constant (low-k) material is a good candidate for advanced interconnect technology. Good thermal stability of the dielectric is required due to the many thermal processes involved during IC fabrication. The thermal stability of tetramethylcyclotetrasiloxane (TMCTS) based plasma-enhanced chemical vapor deposition (PECVD) carbon doped low-k material with annealing temperature from 400 to 800 degrees C in N2 was studied. The thermal stability temperature of TMCTS based carbon doped low-k material is 600 degrees C. Above 600 degrees C annealing, the thermal energy can break Si-CH3, Si-C, Si-H, and C-H bonds leading to outgasing, which results in film composition change, weight loss, and thickness shrinkage. Film composition changes, especially carbon loss and oxygen incorporation, can degrade its reliability extremely. Carbon is desorbed in the form of CH4, CO, and other hydrocarbon.