Contribution of Aboveground Litter Decomposition to Soil Respiration in a Subtropical Coniferous Plantation in Southern China

Yidong Wang,Huimin Wang,Zeqing Ma,Wuefa Wen,Qingkang Li,Yunfen Liu,Wiaomin Sun,Guirui Yu 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.2

Soil CO₂ efflux (RS) was monitored in a 23-year-old subtropical coniferous plantation in southern China from January 2004 to December 2006. Field measurements of RS with litterfall (CK) and without litterfall (NL) were conducted to evaluate the contribution of aboveground litter decomposition to RS. The results indicated that annual RS from CK ranged from 11.5 mg (C) m<SUP>-2</SUP>h<SUP>-1</SUP> in 2004 to 186.2 ㎎ (C) m<SUP>-2</SUP>h<SUP>-1</SUP> in 2006. The RS of NL was significantly lower than the RS of CK. RS was mainly determined by soil temperature (TS), but it was also affected by soil moisture. Together, both factors explained > 70%of the observed variations in RS. The temperature sensitivity (Q<SUB>10</SUB>) of RS from NLwas lower than that from CK by considering the soil moisture effect. On average, the annual RS of the coniferous plantation was estimated to be 669 g (C)m<SUP>-2</SUP>yr<SUP>-1</SUP> over the study period. The litterfall greatly enhanced the RS, and the respiration from aboveground litter accounted for about 33% of the total RS, in which the fresh litterfall decomposition accounted for a large proportion. The carbon pool of aboveground litter in this young conifer forest is expected to increase continuously.

Fractal Crushing of Solid Particles

Yidong Wang,Chengjian Shao,Yongfu Xu 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

It does not have widely accepted theory to study particle crushing up to now because of the complex and irregular physical structure of the particles. Fractal theory, which employs statistical concepts in order to explain particle crushing, may provide a solution to this problem. The particle size distributions are introduced to determine the fractal dimension. The relationship among the particle size, the crushing strength, crushing energy and the probability of survival of the particles are established based on the fractal model. The theoretical results are based on the spherical particles and ideal crushing experiments under static load. A total of 500 single slag particle crushing tests are carried out for natural slag particles of 2 to 35 mm in diameter. The agreement between the experimental and the theoretical results of the slag particles seems to be satisfactory. The method introduced in this paper not only apply to slag particles, but also any other fractal particles.

Fast numerical simulation of sheet metal forming using the program QuickForm

Yidong Bao,Junwei Chen,Zhiguo Wang,Wenliang Chen,Wing Lee 한국소성가공학회 2010 기타자료 Vol.2010 No.6

The fast numerical simulation system QuickForm has been self-developed specially for sheet metal forming with complex geometries. In order to resolve the convergence problem of static implicit method due to the change of contact state, the uncoupling solution method of the non-linear differential equations is used in QucikForm program. The bending effect and drawing effect during forming procedure are treated into two separate processes in QuickForm system, so this uncoupling solution has two basic steps. Firstly an approximate method named pre-stressed membrane element is used to achieve the intermediate configuration of sheet in this incremental step before incremental step iteration. The sheet shape of intermediate configuration depends on the current tooling position. Secondly the nonlinear material flow within this intermediate configuration is carried out, which means the nodes of deformed sheet can only slide on this form. The highly efficient iterative solver can be used to the solution of linear equations since the improved conditioning of the linear equations resulting from the uncoupling solution. Numerical simulation results of complex parts demonstrate the higher efficiency and accuracy of the proposed special purpose program.

TWO-DIMENSIONAL TOPOLOGY OF COSMOLOGICAL REIONIZATION

Wang, Yougang,Park, Changbom,Xu, Yidong,Chen, Xuelei,Kim, Juhan IOP Publishing 2015 The Astrophysical journal Vol.814 No.1

<P>We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two-dimensional genus curve for the early, middle, and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometre Array.</P>

Mitogen-activated protein kinase 3 and 6 regulate <i>Botrytis cinerea</i>-induced ethylene production in Arabidopsis

Han, Ling,Li, Guo-Jing,Yang, Kwang-Yeol,Mao, Guohong,Wang, Ruigang,Liu, Yidong,Zhang, Shuqun Blackwell Publishing Ltd 2010 The Plant journal Vol.64 No.1

<P>Summary</P><P>Plants challenged by pathogens, especially necrotrophic fungi such as <I>Botrytis cinerea</I>, produce high levels of ethylene. At present, the signaling pathways underlying the induction of ethylene after pathogen infection are largely unknown. MPK6, an Arabidopsis stress-responsive mitogen-activated protein kinase (MAPK) was previously shown to regulate the stability of ACS2 and ACS6, two type I ACS isozymes (1-amino-cyclopropane-1-carboxylic acid synthase). Phosphorylation of ACS2 and ACS6 by MPK6 prevents rapid degradation of ACS2/ACS6 by the 26S proteasome pathway, resulting in an increase in cellular ACS activity and ethylene biosynthesis. Here, we show that MPK3, which shares high homology and common upstream MAPK kinases with MPK6, is also capable of phosphorylating ACS2 and ACS6. In the <I>mpk3</I> mutant background, ethylene production in gain-of-function <I>GVG-NtMEK2</I><SUP><I>DD</I></SUP> transgenic plants was compromised, suggesting that MPK6 and MPK3 function together to stabilize ACS2 and ACS6. Using a liquid-cultured seedling system, we found that <I>B. cinerea</I>-induced ethylene biosynthesis was greatly compromised in <I>mpk3/mpk6</I> double mutant seedlings. In contrast, ethylene production decreased only slightly in the <I>mpk6</I> single mutant and not at all in the <I>mpk3</I> single mutant, demonstrating overlapping roles for these two highly homologous MAPKs in pathogen-induced ethylene induction. Consistent with the role of MPK3/MPK6 in the process, mutation of <I>ACS2</I> and <I>ACS6</I>, two genes encoding downstream substrates of MPK3/MPK6, also reduced <I>B. cinerea</I>-induced ethylene production. The residual levels of ethylene induction in the <I>acs2/acs6</I> double mutant suggest the involvement of additional ACS isoforms, possibly regulated by MAPK-independent pathway(s).</P>

Extracellular products-mediated interspecific interaction between Pseudomonas aeruginosa and Escherichia coli

Yuan Yang,Li Jing,Lin Jiafu,Pan Wenjuan,Chu Yiwen,Prithiviraj Balakrishnan,Guo Yidong,Wang Xinrong,Zhao Kelei 한국미생물학회 2021 The journal of microbiology Vol.59 No.1

The Gram-negative pathogen Pseudomonas aeruginosa adopts several elaborate strategies to colonize a wide range of natural or clinical niches and to overcome the neighboring bacterial competitors in polymicrobial communities. However, the relationship and interaction mechanism of P. aeruginosa with other bacterial pathogens remains largely unexplored. Here we explore the interaction dynamics of P. aeruginosa and Escherichia coli, which frequently coinfect the lungs of immunocompromised hosts, by using a series of on-plate proximity assays and RNA-sequencing. We show that the extracellular products of P. aeruginosa can inhibit the growth of neighboring E. coli and induce a large-scale of transcriptional reprogramming of E. coli, especially in terms of cellular respiration- related primary metabolisms and membrane components. In contrast, the presence of E. coli has no significant effect on the growth of P. aeruginosa in short-term culture, but causes a dysregulated expression of genes positively controlled by the quorum-sensing (QS) system of P. aeruginosa during subsequent pairwise culture. We further demonstrate that the divergent QS-regulation of P. aeruginosa may be related to the function of the transcriptional regulator PqsR, which can be enhanced by E. coli culture supernatant to increase the pyocyanin production by P. aeruginosa in the absence of the central las-QS system. Moreover, the extracellular products of E. coli promote the proliferation and lethality of P. aeruginosa in infecting the Caenorhabditis elegans model. The current study provides a general characterization of the extracellular products-mediated interactions between P. aeruginosa and E. coli, and may facilitate the understanding of polymicrobial infections.