Showing papers by "Lixin Wang published in 2013"
TL;DR: Results showed that cyanidin 3-galactoside (cy3-gal) was the most abundant anthocyanin in both non-red and red cultivars, indicating that red color was easier to develop in green cultivar ‘Granny Smith’ than in yellow cultivars ‘Golden Delicious’ after bag removal.
Abstract: In the present study, evolution of apple color (L* and a/b), the accumulation of anthocyanins and the activity of the related enzymes, phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), dihydroflavonol4-reductase (DFR) and UDP-Glucose: flavonoid-3-O-galactosyl transferase (UFGT), were investigated in bagged non-red apple cultivars ('Granny Smith' and 'Golden Delicious') and red apple cultivars ('Starkrimon' and 'Pink Lady'). Young fruits were bagged 40-45 days after flowering (DAF), and fruits of 'Golden Delicious' and 'Starkrimon' were uncovered and exposed to light 120 DAF, while those of 'Granny Smith' and 'Pink Lady' were exposed for 160 DAF. Results showed that cyanidin 3-galactoside (cy3-gal) was the most abundant anthocyanin in both non-red and red cultivars. Level of anthocyanins was higher in 'Granny Smith' than in 'Golden Delicious', indicating that red color was easier to develop in green cultivar 'Granny Smith' than in yellow cultivar 'Golden Delicious' after bag removal. The cy3-gal accumulation of non-red cultivars tested was not significantly correlated with PAL, CHI and DFR activity, but was significantly correlated with UFGT activity. During the reddening of non-red apples, UFGT may be the more important factor in the anthocyanin biosynthesis.
77 citations
TL;DR: In this paper, a Li-air cell using an air cathode consisting of nano-Pt on graphene nanosheets (GNS) has shown promising performance at 80% energy efficiency with an average capacity of 1200 mg−1 and more than 20 cycles without significant loss of total energy efficiency.
72 citations
TL;DR: In this paper, the authors explored the use of atmospheric back-trajectory modeling and associated meteorological variables to explain the large variability observed in the isotopic composition of individual rain events at the study site in central Kenya.
Abstract: The isotopic composition of rainfall (δ2H and δ18O) is an important tracer in studies of the ecohydrology, plant physiology, climate and biogeochemistry of past and present ecosystems. The overall continental and global patterns in precipitation isotopic composition are fairly well described by condensation temperature and Rayleigh fractionation during rainout. However, these processes do not fully explain the isotopic variability in the tropics, where intra-storm and meso-scale dynamics may dominate. Here we explore the use of atmospheric back-trajectory modeling and associated meteorological variables to explain the large variability observed in the isotopic composition of individual rain events at the study site in central Kenya. Individual rain event samples collected at the study site (n = 41) range from −51‰ to 31‰ for δ2H and the corresponding monthly values (rain volume-weighted) range from −15‰ to 15‰. Using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, we map back-...
68 citations
TL;DR: In this article, a stable isotope approach was used to estimate the isotopic composition of evaporation, transpiration and the aggregated evapotranspiration in a grassland ecosystem.
63 citations
TL;DR: Stochastic profiling surveys the transcriptome for programs that are heterogeneously regulated among cellular subpopulations in their native tissue context by repeatedly sampling small collections of cells selected at random.
Abstract: Single-cell variations in gene and protein expression are important during development and disease. Such cell-to-cell heterogeneities can be directly inspected one cell at a time, but global methods are usually not sensitive enough to work with the starting material of a single cell. Here we provide a detailed protocol for stochastic profiling, a method that infers single-cell regulatory heterogeneities by repeatedly sampling small collections of cells selected at random. Repeated stochastic sampling is performed by laser-capture microdissection or limiting dilution, followed by careful exponential cDNA amplification, hybridization to microarrays and statistical analysis. Stochastic profiling surveys the transcriptome for programs that are heterogeneously regulated among cellular subpopulations in their native tissue context. The protocol is readily optimized for specific biological applications and takes about 1 week to complete.
39 citations
TL;DR: Zhang et al. as mentioned in this paper measured and analyzed the changes in anthocyanins, phenolic compounds and expression of the key Anthocyanin biosynthetic and regulatory genes in the colored process of Granny Smith apples.
Abstract: In the Loess Plateau region of China, it was discovered that the famous green-skinned apple cultivar ‘Granny Smith’ could rapidly turn red following bag removal. In order to clarify the reasons for the color formation, we measured and analyzed the changes in anthocyanins, phenolic compounds and expression of the key anthocyanin biosynthetic and regulatory genes in the colored process of ‘Granny Smith’ apples. The results indicated that two types of anthocyanins (i.e., cyanidin 3-O-galactoside and cyanidin 3-O-arabinoside) could be detected in the skin of ‘Granny Smith’ apples after bag removal. Cyanidin 3-O-galactoside accounted for most of the total anthocyanin contents and significantly accumulated within 7 days, along with the concentrations of chlorophylls and carotenoids significantly decreasing. The concentrations of catechin and procyanidin B2 in bagged apples also noticeably decreased, while the concentration of epicatechin increased. After bag removal, the expression of MdDFR, MdANS and MdUFGT increased sharply within 7 days. The transcription level of MdMYB10 and MdBHLH33 was markedly up-regulated and peaked at 1 day. While in the non-bagged apples, little anthocyanins were found and the expression of those genes showed low levels and remained stable. Our results suggested that ‘Granny Smith’ apples, in the special growing conditions of the Loess Plateau region of China, had the potential ability of coloration. And the higher expression of MdDFR, MdANS, MdUFGT, MdMYB10 and MdBHLH33 genes could enhance anthocyanin accumulation on ‘Granny Smith’ apples.
32 citations
TL;DR: In this article, the effects of soil moisture and vegetation distribution on ecosystem-scale patterns of soil δ15N were investigated at sub-kilometer scales using two sites (dry vs. wet) from a megatransect in southern Africa.
Abstract: Soil 15N is a natural tracer of nitrogen (N) cycling. Its spatial distribution is a good indicator of processes that are critical to N cycling and of their controlling factors integrated both in time and space. The spatial distribution of soil δ15N and its underlying drivers at sub-kilometer scales are rarely investigated. This study utilizes two sites (dry vs. wet) from a megatransect in southern Africa encompassing locations with similar soil substrate but different rainfall and vegetation, to explore the effects of soil moisture and vegetation distribution on ecosystem-scale patterns of soil δ15N. A 300-m long transect was set up at each site and surface soil samples were randomly collected for analyses of δ15N, %N and nitrate content. At each soil sampling location the presence of grasses, woody plants, Acacia species (potential N fixer) as well as soil moisture levels were recorded. A spatial pattern of soil δ15N existed at the dry site, but not at the wet site. Woody cover distribution determined the soil δ15N spatial pattern at ecosystem-scale; however, the two Acacia species did not contribute to the spatial pattern of soil δ15N. Grass cover was negatively correlated with soil δ15N at both sites owing to the lower foliar δ15N values of grasses. Soil moisture did not play a role in the spatial pattern of soil δ15N at either site. These results suggest that vegetation distribution, directly, and water availability, indirectly, affect the spatial patterns of soil δ15N through their effects on woody plant and grass distributions.
29 citations
TL;DR: In this paper, the authors examined the spatial patterns of infiltration across three treatments relating to shrub removal and grazing: (i) undisturbed (ungrazed, unploughed), (ii) grazed but unploughhed, and (iii) ploughed and rammed.
27 citations
TL;DR: In this article, the authors examined the effects of two land management practices, grazing and ploughing, on the spatial distribution of surface soil resources, and found that grazing alone, or in combination with ploughs, leads to reduced connectivity of shrub and crust cover, reduction in crust patterning, and marked effects on shrub-litter-nutrient spatial relationships.
23 citations
TL;DR: In this paper, the effects of litter mixing and position on decomposition rates and nitrogen (N) and phosphorus (P) dynamics were examined using a three-year decomposition experiment.
Abstract: Mixing effects during litter decomposition could occur between two or more different litter species because of the potential nutrient transfer. However, evidence of mixing effects is variable and the underlying mechanisms remain unclear. Using a three-year decomposition experiment, we aim to examine for the effects of litter mixing and position on decomposition rates and nitrogen (N) and phosphorus (P) dynamics. We studied litter decomposition of Stipa krylovii (Sk) and Astragalus galactites (Ag), two dominant species with contrasting litter quality, in a typical steppe of northern China in both single decomposition and three mixing treatments. The three mixing treatments included thorough mixing (Sk-Ag), Ag over Sk (Ag/Sk), and Sk over Ag (Sk/Ag). Both the Sk-Ag and the Sk/Ag mixture had negative mixing effects on the mass loss of the litter mixture, while the Ag/Sk mixture had a neutral mixing effect. The percent mass loss was higher when the litter species was placed at the top (25.0 and 51.9 % of mass remaining for Ag and Sk, respectively) than at the bottom (38.3 and 61.8 % of mass remaining for Ag and Sk, respectively). The Sk/Ag mixture had negative effects on the release of N while all three mixing treatments had positive effects on the release of P. Our results indicate that: (1) mixing treatments can induce different mixing effects; (2) environmental factors likely play an important role in controlling the mixing effect; and (3) litter-mixtures have different non-additive effects on N and P, which may further increase the heterogeneity of N and P availability as the two litter species may fall differentially in terms of space and time.
17 citations
TL;DR: In this paper, the 3D composites of integrated 1D MnO2 nanowires and 2D graphene sheets at nanoscale are successfully prepared under the mild condition of 100°C.
Abstract: Composites of integrated 1-D MnO2 nanowires and 2-D graphene sheets at nanoscale are successfully prepared under the mild condition of 100 °C. The fabricated materials are extensively characterized by electron microscopy and X-ray diffraction, and the formation mechanism is investigated. It is of particular note that the graphene sheets in this case play dual roles, both as active reagent to reduce MnO4− to form 1-D MnO2 nanowires and as active component of the composites integrated into the 3-D structure. The proof-of-concept demonstration shows that the 3-D composites can be used as active materials for supercapacitors, where the high-surface area 2-D graphene sheets serve as both high-surface area active materials and conductive supports for high-capacity 1-D MnO2 nanowires.
TL;DR: A greedy approximation algorithm for computing a Minimum CDS in multihop wireless networks with disparate communications ranges is presented and it is proved that its approximation ratio is better than the best one known in the literature.
Abstract: Connected dominating set (CDS) has a wide range of applications in multihop wireless networks. The Minimum CDS problem has been studied extensively in multihop wireless networks with uniform communication ranges. However, in practice, the nodes may have different communication ranges either because of the heterogeneity of the nodes, or due to interference mitigation, or due to a chosen range assignment for energy conservation. In this paper, we present a greedy approximation algorithm for computing a Minimum CDS in multihop wireless networks with disparate communications ranges and prove that its approximation ratio is better than the best one known in the literature. Our analysis utilizes a tighter relation between the independence number and the connected domination number.
TL;DR: The results indicate that these sand-binding plants have developed into a relatively stable stage and they are able to regulate their nitrogen and water use in responding to environmental conditions, which reinforces the effectiveness of plantation of native shrubs without irrigation in degraded areas, however, the results also indicate that short-term climate variability could have severe impact on the vegetation functions.
Patent•
11 Apr 2013
TL;DR: In this paper, a method of creating a supercapacitor comprising sheets of graphene and metal oxide nanowires is described, in particular managanese dioxide as it has excellent pseudocapacitative properties, but the use of other metal oxides is possible.
Abstract: A method of creating a supercapacitor comprising sheets of graphene and metal oxide nanowires is described. In particular, managanese dioxide is chosen as it has excellent pseudocapacitative properties, but the use of other metal oxides is possible. Ideal incubation times, temperatures, concentrations, and ratios were experimentally determined. The electrochemically active compound generated is then posited on a porous metal surface, such as nickel foam, and infiltrated with an aqueous or ionic electrolyte. Supercapacitors of this construction display excellent conductivity, ability to hold charge, and cyclability.
01 Dec 2013
TL;DR: These findings provide the first experimental evidence in support of the involvement of ethylene in nitrogen-induced decrease in leaf longevity, mainly through altering leaf ethylene production.
Abstract: †Background and Aims Leaf longevity is an important plant functional trait that often varies with soil nitrogensupply.Ethyleneisaclassicalplanthormoneinvolvedinthecontrolofsenescenceandabscission,butitsroleinni-trogen-dependentleaf longevity is largely unknown.†MethodsPotandfieldexperimentswereperformedtoexaminetheeffectsofnitrogenadditiononleaflongevityandethyleneproductionintwodominantplantspecies,AgropyroncristatumandStipakrylovii,inatemperatesteppeinnorthern China.†KeyResultsNitrogenadditionincreasedleafethyleneproductionandnitrogenconcentrationbutshortenedleaflon-gevity; the addition of cobalt chloride, an ethylene biosynthesis inhibitor, reduced leaf nitrogen concentration andincreasedleaflongevity.Pathanalysisindicatedthatnitrogenadditionreducedleaflongevitymainlythroughalteringleaf ethylene production.†Conclusions These findings provide the first experimental evidence in support of the involvement of ethylene innitrogen-induced decrease in leaf longevity.Key words: Agropyroncristatum,Stipakrylovii,ethyleneproduction,InnerMongolia,leaflifespan,leafnitrogen,grassland, nitrogen addition.
TL;DR: In this article, the authors provided the first experimental evidence in support of the involvement of ethylene in a decrease in leaf longevity, showing that the addition of cobalt chloride, an ethylene biosynthesis inhibitor, reduced leaf nitrogen concentration and increased leaf longevity.
14 Oct 2013
TL;DR: This paper investigates the connectivity of multihop wireless networks with the log-normal shadowing model by investigating the critical transmission power required by each node for asymptotic vanishing of the isolated notes in the network.
Abstract: In this paper, we study the connectivity of multihop wireless networks with the log-normal shadowing model by investigating the critical transmission power required by each node for asymptotic vanishing of the isolated notes in the network. The vanishing of isolated nodes is not only a prerequisite but also a good indication of network connectivity. All previous known work on network connectivity under such a shadowing model were obtained only based on simulation studies or ignoring the important boundary effect to avoid the challenging technical analysis, and thus cannot be applied to any practical wireless networks. It is extremely challenging to take the complicated boundary effect into consideration under such a realistic model because the transmission area of each node is an irregular region other than a circular area. We assume the wireless nodes are represented by a Poisson point process with density n over a unit-area disk. With the complicated boundary effect taken into consideration, we first derive an explicit formula for the expected number of isolated nodes in the network. This explicit formula allows people to control the expected number of isolated nodes by tuning the node density or even the transmission power, and thus the desired level of network connectivity can be expected. Then we give an upper bound and a lower bound of the critical transmission power for asymptotic vanishing of the isolated nodes. Our upper and lower bounds for the critical transmission power used by each node are almost tight.