山西云蒙山油松种群的年龄结构和动态特征

本文用样方法研究了山西云蒙山油松种群的年龄结构、存活曲线和数量动态规律,并且讨论了油松种群数量动态和群落演替的关系,结果表明:油松种群具有增长型和衰退型的动态特征,影响油松种群数量的内在机制主要是种内光资源的竞争。尽管大多数油松种群处于不断衰减状态,但其群落结构及性质在较长时期内将不会发生显著的变化。     

Quantification of methane emissions from Chinese rice fields (Zhejiang Province) as influenced by fertilizer treatment

Methane emissions from rice paddies were quantified by using an automatic field system stationed in Zhejiang Province, one of the centres for rice cultivation in China. The data set showed pronouned interannual variations over 5 consecutive vegetation periods; by computing average values of all experimental plots the annual emissions were 177 g CH₄ m⁻² yr⁻¹ in 1987, 50 g CH₄ m⁻² yr⁻¹ in 1988, and 187 g CH₄ m⁻² yr⁻¹ in 1989. The field preparations encompassed 4 different treatments: (1) no fertilizers, (2) mineral fertilizer (KCl, K₂SO₄), (3) organic manure (rape seeed cake, animal manure), (4) mineral fertilizer plus organic manure. The methane emission rates of the different fertilizer treatments did not show significant differences. The mean emission rates, calculated over the entire observation period of 5 seasons, were 30.4 mg CH₄ m⁻² h⁻¹ (non-fertilized plot) and 28.3 mg CH₄ m⁻² h⁻¹ (mineral fertilizers). These values indicate a high level of methane production even without additional input of organic material into the rice-soils. In the other plots, the organic fertilizers were added once per vegetation period at app. 1 t fresh weight per ha, a relatively low application rate by agronomical standards. The mean emission rates were 35.1 mg CH₄ m⁻² h⁻¹ when manure was applied as sole fertilizer and 27.5 mg CH₄ m⁻² h⁻¹ when applied jointly with potassium fertilizers. Based on the results of this study we estimate a range of 18–28 Tg CH₄ yr⁻¹ as the total methane emission from Chinese rice fields. However, more field data from representative sites in China are needed to reduce the uncertainties in this estimate.     

Bimetallic Cobalt‐Based Phosphide Zeolitic Imidazolate Framework: CoPx Phase‐Dependent Electrical Conductivity and Hydrogen Atom Adsorption Energy for Efficient Overall Water Splitting

Cobalt‐based bimetallic phosphide encapsulated in carbonized zeolitic imadazolate frameworks has been successfully synthesized and showed excellent activities toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory calculation and electrochemical measurements reveal that the electrical conductivity and electrochemical activity are closely associated with the Co₂P/CoP mixed phase behaviors upon Cu metal doping. This relationship is found to be the decisive factor for enhanced electrocatalytic performance. Moreover, the precise control of Cu content in Co‐host lattice effectively alters the Gibbs free energy for H* adsorption, which is favorable for facilitating reaction kinetics. Impressively, an optimized performance has been achieved with mild Cu doping in Cu_0.3Co_2.7P/nitrogen‐doped carbon (NC) which exhibits an ultralow overpotential of 0.19 V at 10 mA cm^–2 and satisfying stability for OER. Cu_0.3Co_2.7P/NC also shows excellent HER activity, affording a current density of 10 mA cm^–2 at a low overpotential of 0.22 V. In addition, a homemade electrolyzer with Cu_0.3Co_2.7P/NC paired electrodes shows 60% larger current density than Pt/RuO₂ couple at 1.74 V, along with negligible catalytic deactivation after 50 h operation. The manipulation of electronic structure by controlled incorporation of second metal sheds light on understanding and synthesizing bimetallic transition metal phosphides for electrolysis‐based energy conversion.     

Association of Porcine IGF Binding Protein-5 Gene with Meat Quality

IGFBP-5 is a member of the IGF families. Using PCR-SSCP, genotypic and allelic frequencies were analyzed in 18 pig breeds (n = 600). The association between haplotypes and production performance was analyzed in a Jinhua × Pietrain population family (n = 212, total 24 traits). Two SNPs (T199C and G485A) within the gene were analyzed. The breeds had different genotypic and allelic frequencies. Typically, the Chinese native pig breeds carried a higher allele C and G frequency (over 50%) than those of the European pigs, and only Guangdong Large White and wild boar were at Hardy–Weinberg equilibrium. The pigs carrying the CG haplotype had higher hue, loin, and thigh pH1 values than pigs with the TA haplotype, and pigs with the TA haplotype had the lowest loin pH2 value and highest color-a value among the haplotypes. It is proposed that the IGFBP-5 gene is associated with the variation in meat quality, especially in pH value together with other QTLs on chromosome 15.     

植物根系分泌物主要生态功能研究进展

根系分泌物在植物根系-土壤-微生物互作过程及其生态反馈机制中发挥重要作用。在植物根际复杂网络互作过程中, 根系分泌物被认为是“根际对话”的媒介, 其在调控植物适应微生境、缓解根际养分竞争及构建根际微生物群落结构方面意义重大。该文结合国内外该领域主要研究成果, 综述了根系分泌物对植物生长、土壤微生物特性及土壤养分循环的影响, 并展望了未来根系分泌物的研究方向。     

Sensitive and antifouling impedimetric aptasensor for the determination of thrombin in undiluted serum sample

A highly sensitive and attractive antifouling impedimetric aptasensor for the determination of thrombin in undiluted serum sample was developed. The aptasensor was fabricated by co-assembling thiol-modified anti-thrombin binding aptamer, dithiothreitol and mercaptohexanol on the surface of gold electrode. The performance of aptasensor was characterized by atomic force microscopy, contact angle and electrochemical impedance spectroscopy. In the measurement of thrombin, the change in interfacial electron transfer resistance of aptasensor was monitored using a redox couple of Fe(CN)(6)(3-/4-). The increase in the electron transfer resistance was linearly proportional to the concentration of thrombin in the range from 1.0 to 20ng/mL and a detection limit of 0.3ng/mL thrombin was achieved. The fabricated aptasensor displayed attractive antifouling properties and allowed direct quantification of extrinsic thrombin down to 0.08ng/mL in undiluted serum sample. This work provides a promising strategy for clinical application with impressive sensitivity and antifouling characteristics.