Soil C, N and P stoichiometry in different forest stand types in the middle and lower reaches of the Beijiang River, China.

We examined the vertical distribution characteristics of soil organic carbon (C), total nitrogen (N), total phosphorus (P) and their ecological stoichiometric ratios in 0-80 cm soil profile under three forest stand types in the middle and lower reaches of the Beijiang River, including broad-leaved forest, coniferous forest, and mixed coniferous and broad-leaved forest. The results showed that soil C, N and P contents of the three forest stand types were 12.17-14.25, 1.14-1.31, and 0.27-0.30 g·kg-1, respectively. The contents of C and N decreased with the increases of soil depth. The content of C and N in each soil layer showed that coniferous and broad-leaved mixed forest > coniferous forest > broad-leaved forest. There was no significant difference in P content among the three stand types, and there was no obvious variation in the vertical profile. The soil C/N, C/P, and N/P of the three forest types were 11.2-11.3, 49.0-60.3, and 4.5-5.7, respectively. There was no significant difference in soil C/N among the three stand types. The highest soil C/P and N/P were found in the mixed forest. There was no interaction between soil depth and stand type in affecting soil C, N, P contents and their stoichiometric ratios. There was significant positive correlation between C and N, and between N and C/P in each stand type and soil layer. Soil C/P and N/P had stronger ecological indicating effects on stand types. The coniferous and broad-leaved mixed forest was strongly limited by P availability.

Superimposed OER and UOR performances by the interaction of each component in an Fe-Mn electrocatalyst.

The oxygen evolution reaction (OER) and alternative urea oxidation reaction (UOR) are both important half reactions correlated with hydrogen production. Transition metal based catalysts with double metal composition exhibit excellent electrocatalytic performance for the OER or UOR due to their synergetic effect and coupling of different active sites. However, the development of OER/UOR bifunctional electrocatalysts is unsatisfying and the role of each metallic active site in the OER and UOR is still unclear. Herein, we report a Fe-Mn based OER and UOR bifunctional catalyst through a simple one-step electrodeposition method. For the OER, the introduction of Mn improves the conductivity of the catalysts and fine-tunes the electron density of the Fe active sites. For the UOR, both Fe and Mn act as active sites and their coupling effect further improves the UOR activity. The catalyst with the optimal Mn/Fe ratio achieved an overpotential of 237 mV for the OER and a potential of 1.35 V for the UOR at 100 mA cm-2. This study provides a simple synthesis protocol for constructing bifunctional catalysts for green hydrogen production.

The complete chloroplast genome sequence of Butea monosperma (Fabaceae).

Butea monosperma, an importantmedicinal plantin Fabaceae, is mainly distributed in southern Asia. In this study, we reported the complete chloroplast (cp) genome of B. monosperma assembled with Illumina sequencing data. The whole cp genome of this species is 151,925 bp in length, consisting of two inverted repeat regions (IR, 25,083 bp), one large single-copy region (LSC, 83,541 bp), and one small single-copy region (SSC, 18,218 bp).A total of 128 genes were annotated for the chloroplast genome, including 83 protein-coding genes, 37 tRNAs and 8 rRNAs. Phylogenetic analysis indicated that B. monosperma was closely related to the genus Lespedeza.

Accumulation and stripping behavior of silver ions at dl-dithiothreitol self-assembled monolayer modified gold electrodes.

Silver ions can be entrapped at the dl-dithiothreitol (HSCH(2)(CHOH)(2)CH(2)SH, DTT) self-assembled monolayer films modified gold electrodes. When the potential was made moving, an anodic peak was observed at about 0.23 V (vs. SCE). When the electrode Au/DTT was modified with dodecyl mercaptan further, more Ag (I) can be accumulated and the peak grows. Conditions, such as solution pH and supporting electrolyte, were optimized for Ag (I) determination. Under the selected conditions, i.e. 0.010 M pH 4.3 potassium hydrogen phthalate, preconcentration time of 5 min at open circuit, the anodic peak height is linear to the concentration of Ag (I) in the small range of 0.6-2.4 muM. The influence of some ions on the determination of Ag (I) was examined. The Br(-) ion makes the peak decrease and NCS(-) makes the peak increase. But the determination is not interfered by 1000-fold Pb(2+), Cd(2+), Hg(2+), Fe(3+), Ni(2+), Co(2+), Cu(2+) and Sn(2+) when EDTA was added into the solution. The mechanism involved was discussed.

Electrochemical study and detection of perphenazine using a gold electrode modified with decanethiol SAM.

A novel method for the determination of perphenazine has been developed. The method is based on the accumulation of perphenazine at a gold electrode modified with decanethiol (DEC) self-assembled monolayer (SAM) and its oxidation at about 0.6 V (vs. saturated calomel electrode (SCE)). Because some coexistent electroactives were blocked and perphenazine was selectively accumulated by the SAM, the electrode exhibited good selectivity and sensitivity. Various conditions were optimized for practical application. Under the selected conditions (i.e. 0.05 M pH 10 sodium borate buffer, accumulation time: 120 s, accumulation potential: -0.4 V, scan rate: 100 mV s(-1)), the anodic stripping peak current was linear to perphenazine concentration in the ranges of 6x10(-9)-5xl0(-7) and 5x10(-7)-5x10(-6) M with correlation coefficients of 0.998 and 0.995, respectively. For a 1.0x10(-6) M perphenazine solution, the relative standard deviation of peak height was 2.3% (n=8). This method was applied to the determination of perphenazine in some drugs and the recovery was 92-101%. In addition, it was found that in the presence of perphenazine, the SAM structure changed a little and more needle holes appeared. However, the SAM could recover the original form when perphenazine and its redox product were removed from the monolayer by repeatedly cycling the electrode in a blank solution for a minute. The modified electrode was characterized by alternating current impedance and electrochemical probe.