Spatial patterns of greenhouse gas emission in a tropical rainforest in Indonesia

Spatial patterns of CO₂, CH₄, and N₂O flux were analyzed in the soil of a primary forest in Sumatra, Indonesia. The fluxes were measured at 3-m intervals on a sampling grid of 8 rows by 10 columns, with fluxes found to be below the minimum detection level at 12 points for CH₄ and 29 points for N₂O. All three gas fluxes distributed log-normally. The means and standard deviations of CO₂ and CH₄ fluxes calculated by the maximum likelihood method were 3.68 ± 1.32 g C m^–2 d^–1 and 0.79 ± 0.60 mg C m^–2 d^–1, respectively. The mean and standard deviation of N₂O fluxes using a maximum likelihood estimator for the censored data set was 2.99 ± 3.26 g N m^–2 h^–1. The spatial dependency of CH₄ fluxes was not detected in 3-m intervals, while weak spatial dependency was observed in CO₂ and N₂O fluxes. The coefficients of variation of CH₄ and N₂O were higher than that of CO₂. Some hot spots where high levels of CH₄ and N₂O were generated in the studied field may increase the variability of these gases. The resulting patterns of variability suggest that sampling distances of >10 m and > 20 m are required to obtain statistically independent samples for CO₂ and N₂O flux in the studied field, respectively. But because of weak or no spatial dependency of each flux, a sampling distance of more than 10 m intervals is enough to prevent a significant problem of autocorrelation for each flux measurement.     

Swelling behaviour of poly(α‐hydroxyacrylic acid) gel

Poly(α‐hydroxy acrylic acid) (PHA) and poly(acrylicacid) (PAA) gels were prepared by irradiating the respective 15 wt% aqueous solutions with γ‐rays. Swelling ratios for PHA gel were measured as a function of pH and divalent cation (Mg²⁺, Ca²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺) concentration C₂ in the external solution to provide a comparison with the results for PAA gels. It was found that the swelling ratio of PHA gel steeply increases between pH 2 and 4, followed by a gradual swelling in the higher pH region. The corresponding steep swelling of PAA gel was observed at pH 3–6. Cation specificity in the equilibrium swelling ratio at a lower C₂ value (1.0 × 10⁻³ M) was approximately consistent with the binding selectivity in the solution system. Typically, the swelling ratio of PHA gel in the presence of Ca²⁺ was significantly lower than in the Mg²⁺ system, while the difference was slight for PAA gel. The response of the swelling ratio to changes in pH and C₂ was analysed as a first order relaxation to estimate the time constants. The (de)swelling kinetics measured by both the pH and C₂ jump were qualitatively interpreted in terms of main‐chain stiffness and intermolecular hydrogen bonding in the respective polymers. © 2000 Society of Chemical Industry     

Effect of binder content on the cycle performance of nano-sized Fe2O3-loaded carbon for use as a lithium battery negative electrode

Nano-sized Fe₂O₃-loaded carbon material was prepared by loading Fe₂O₃ on carbon using various carbonaceous materials. Carbonaceous materials strongly affected the electrochemical behavior of nano-sized Fe₂O₃-loaded carbon. In addition, the binder content also significantly affected the cycle performance of nano-sized Fe₂O₃-loaded carbon. The content of binder depended on the type of carbon used. In the optimal condition for binder content, nano-carbons such as acetylene black (AB), tubular carbon nanofibers (CNF), and platelet CNF provided larger capacities than graphite, and tubular CNF showed the greatest capacity after long-term cycling.     

Enhancement of NO-elimination activity of Co-silicate catalyst by high-temperature calcination in steam-containing air

H–Co-silicate having an MFI structure (CoMFI), calcined in steam-containing air at 800°C (CoMFI-800S), was characterized by XRD and diffuse reflectance electron absorption (EA). The calcination educed some of the Co ions from the CoMFI framework to make small clusters nearby. The CoMFI-800S performance in NO elimination in the presence of excess O₂ was compared with that of Co supported on siliceous MFI zeolite ([Co]SiMFI), Co supported on H–Co-silicate ([Co]CoMFI), and a physical mixture of CoMFI and [Co]SiMFI (Co+[Co]). The educed Co ions enhanced NO elimination due to the uniform and isolated dispersion of oxidized Co clusters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of <Emphasis Type="Italic">Rhizopus delemar</Emphasis> lipase as compared with other lipases for determination of <Emphasis Type="Italic">sn</Emphasis>-2 fatty acids in triacylglycerol

The FA composition in the sn-2 position of TAG is routinely determined after porcine pancreatic lipase hydrolysis. However, the content of saturated FA increased when a pancreatic lipase preparation with higher specific activity was used. Lipase from Rhizopus delemar was selected as a potential replacement lipase for the following reasons: (i) The FA specificity is nearly equivalent in hydrolysis activity toward FA such as lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and α-linolenic acids; and (ii) lipase from R. delemar hydrolyzes fatty acyl residues at the sn-1,3 positions of TAG. Acyl migration products were present at less than 0.8% in lipase hydrolysates containing 6–14% of sn-2 MAG. A reproducibility CV of less than 5% was obtained in a collaborative study in which the compositions of the main FA at the sn-2 position in olive oil were determined using lipase from R. delemar. This article was presented in part at the Biocatalysis Symposium, 94th AOCS Annual Meeting & Expo, Kansas City, Missouri, May 2003.     

Surface modification of LiNi1/2Mn3/2O4 thin-films by zirconium alkoxide/PMMA composites and their effects on electrochemical properties

Three kinds of surface modifications were carried out on LiNi_1/2Mn_3/2O₄ thin-films to improve the charge and discharge characteristics of LiNi_1/2Mn_3/2O₄ positive electrodes. Among them, Zr(OBu)₄/poly(methyl methacrylate) (PMMA)-treated LiNi_1/2Mn_3/2O₄ thin-film electrodes showed charge and discharge efficiency of 80–84% in the first cycle, which was much higher than that for an untreated LiNi_1/2Mn_3/2O₄ thin-film electrode (73%). The values of the charge and discharge efficiency were still higher than that for an untreated electrode after the 30th cycle. The charge and discharge curves gave two plateaus at around 4.72 and 4.76 V, which were very similar to those for the untreated electrode. Ac impedance spectroscopy revealed that the surface film resistance should not increase by Zr(OBu)₄/PMMA treatment. XPS measurements suggest that a composite layer should be formed on a LiNi_1/2Mn_3/2O₄ thin-film electrode from PMMA and Zr(OBu)₄-derived compounds introducing an electrolyte. This composite layer was lithium-ion conductive, and was sustainable enough to suppress subsequent decomposition of an electrolyte at potentials as high as 4.7 V.     

Disentangling dynamic changes of multiple cellular components during the yeast cell cycle by in vivo multivariate Raman imaging

Cellular processes are intrinsically complex and dynamic, in which a myriad of cellular components including nucleic acids, proteins, membranes, and organelles are involved and undergo spatiotemporal changes. Label-free Raman imaging has proven powerful for studying such dynamic behaviors in vivo and at the molecular level. To construct Raman images, univariate data analysis has been commonly employed, but it cannot be free from uncertainties due to severely overlapped spectral information. Here, we demonstrate multivariate curve resolution analysis for time-lapse Raman imaging of a single dividing yeast cell. A four-dimensional (spectral variable, spatial positions in the two-dimensional image plane, and time sequence) Raman data "hypercube" is unfolded to a two-way array and then analyzed globally using multivariate curve resolution. The multivariate Raman imaging thus accomplished successfully disentangles dynamic changes of both concentrations and distributions of major cellular components (lipids, proteins, and polysaccharides) during the cell cycle of the yeast cell. The results show a drastic decrease in the amount of lipids by ~50% after cell division and uncover a protein-associated component that has not been detected with previous univariate approaches.