Showing papers by "Chinese Academy of Sciences published in 1999"
TL;DR: Masses of single-walled carbon nanotubes, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states and show promise as an effective hydrogen storage material.
Abstract: Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a modestly high pressure (about 10 megapascal) for a SWNT sample of about 500 milligram weight that was soaked in hydrochloric acid and then heat-treated in vacuum. Moreover, 78.3 percent of the adsorbed hydrogen (3.3 weight percent) could be released under ambient pressure at room temperature, while the release of the residual stored hydrogen (0.9 weight percent) required some heating of the sample. Because the SWNTs can be easily produced and show reproducible and modestly high hydrogen uptake at room temperature, they show promise as an effective hydrogen storage material.
1,745 citations
TL;DR: In this article, the growth mechanism and growth habit of oxide crystals are investigated from a kinetics viewpoint, starting from the hypothesis of growth unit, and a new rule concerning the growth habit is deduced considering the relation between the growth rate and the orientation of the coordination polyhedron at the interface.
1,080 citations
TL;DR: PowderX as discussed by the authors is a Windows-95-based program for powder X-ray data processing and analysis, which can be used for plotting Xray patterns, data smoothing, background subtraction, 2 elimination, peak search, indexing and zero-angle error correction.
Abstract: The crystallographic problem: A Windows-95-based program (PowderX) has been written for powder X-ray data processing and analysis. It can be used for plotting X-ray patterns, data smoothing, background subtraction, 2 elimination, peak search, indexing and zero-angle error correction. PowderX can also be used for data format conversions to prepare the input data for Rietveld re®nement and structure determination programs such as DBWS, FULLPROF, GSAS, SIMPRO and EXPO.
828 citations
TL;DR: In this article, a nano-Si composite material (NSCM) has been prepared by mixing nanometer-scale pure Si powder and carbon black, which exhibited an extremely high reversible capacity, over 1700 mAh/g Si, at the tenth cycle.
Abstract: A nano-Si composite material (NSCM) has been prepared by mixing nanometer-scale (78 nm) pure Si powder and carbon black. The electrochemical performance of NSCM anodes for lithium rechargeable batteries exhibited an extremely high reversible capacity, over 1700 mAh/g Si, at the tenth cycle. The voltage profile is flat and smooth ranged from 0.4 to 0.0 V vs. Li/Li+. In addition, the cyclic performance is good even at larger current densities. Consequently, NSCM can be used as a novel high capacity anode material for lithium-ion batteries. (C) 1999 The Electrochemical Society. S1099-0062(98)10-053-6. All rights reserved.
801 citations
TL;DR: This study demonstrates that Amboreella, Nymphaeales and Illiciales-Trimeniaceae-Austrobaileya represent the first stage of angiosperm evolution, with Amborella being sister to all other angiosperms, and shows that Gnetales are related to the conifers and are not sister to the angios perms, thus refuting the Anthophyte Hypothesis.
Abstract: Angiosperms have dominated the Earth's vegetation since the mid-Cretaceous (90 million years ago), providing much of our food, fibre, medicine and timber, yet their origin and early evolution have remained enigmatic for over a century. One part of the enigma lies in the difficulty of identifying the earliest angiosperms; the other involves the uncertainty regarding the sister group of angiosperms among extant and fossil gymnosperms. Here we report a phylogenetic analysis of DNA sequences of five mitochondrial, plastid and nuclear genes (total aligned length 8,733 base pairs), from all basal angiosperm and gymnosperm lineages (105 species, 103 genera and 63 families). Our study demonstrates that Amborella, Nymphaeales and Illiciales-Trimeniaceae-Austrobaileya represent the first stage of angiosperm evolution, with Amborella being sister to all other angiosperms. We also show that Gnetales are related to the conifers and are not sister to the angiosperms, thus refuting the Anthophyte Hypothesis. These results have far-reaching implications for our understanding of diversification, adaptation, genome evolution and development of the angiosperms.
779 citations
TL;DR: Mafic to ultramafic dykes and sills in South China, dated as 828±7 Ma old, are identical in age to the 827±6 Ma Gairdner Dyke Swarm in Australia, thought to be of mantle plume origin this paper.
740 citations
TL;DR: In this paper, the preparation of nylon 6/clay nanocomposites by a melt-intercalation process is proposed, and the results show that the crystal structure and crystallization behaviors of the nanomaterials are different from those of the nylon 6.
Abstract: The preparation of nylon 6/clay nanocomposites by a melt-intercalation process is proposed. X-ray diffraction and DSC results show that the crystal structure and crystallization behaviors of the nanocomposites are different from those of nylon 6. Mechanical and thermal testing shows that the properties of the nanocomposites are superior to nylon 6 in terms of the heat-distortion temperature, strength, and modulus without sacrificing their impact strength. This is due to the nanoscale effects and the strong interaction between the nylon 6 matrix and the clay interface, as revealed by X-ray diffraction, transmission electron microscopy, and Molau testing. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1133–1138, 1999
724 citations
01 May 1999
TL;DR: This paper presents a class of urban models whose dynamics are based on theories of development associated with cellular automata (CA), whose data is fine-grained, and whose simulation requires software which can handle an enormous array of spatial and temporal model outputs.
Abstract: In urban systems modeling, there are many elaborate dynamic models based on intricate decision processes whose simulation must be based on customized software if their space–time properties are to be explored effectively. In this paper we present a class of urban models whose dynamics are based on theories of development associated with cellular automata (CA), whose data is fine-grained, and whose simulation requires software which can handle an enormous array of spatial and temporal model outputs. We first introduce the generic problem of modeling within GIS, noting relevant CA models before outlining a generalized model based on Xie's (1996, A general model for cellular urban dynamics. Geographical Analysis, 28, 350–373) “dynamic urban evolutionary modeling” (DUEM) approach. We present ways in which land uses are structured through their life cycles, and ways in which existing urban activities spawn locations for new activities. We define various decision rules that embed distance and direction, density thresholds, and transition or mutation probabilities into the model's dynamics, and we then outline the software designed to generate effective urban simulations consistent with GIS data inputs, outputs and related functionality. Finally, we present a range of hypothetical urban simulations that illustrate the diversity of model types that can be handled within the framework as a prelude to more realistic applications which will be reported in later papers.
648 citations
TL;DR: In this article, the Shangdan suture and the newly discovered Mianlue suture within the Qinling orogen were identified as the trace along which the North and South China blocks collided.
Abstract: The Qinling orogen was formed by the joining of the North and South China blocks, but the timing of their integration has been debated for more than a decade The controversies obviously stem from different approaches to reconstruction of the integration history Two contrasting lines of evidence yield two different ages for collision of the North and South China blocks—middle Paleozoic and Late Triassic The Shangdan suture within the Qinling was regarded in previous studies as the trace along which the North and South China blocks collided Our studies, however, demonstrate that there are two sutures within the Qinling: the well-documented Shangdan suture and the newly discovered Mianlue suture We show in this paper that the Late Proterozoic to early Mesozoic evolution of the Qinling involved interactions between the North China block, the North and South Qinling orogens, and the South China block The middle Paleozoic collision along the Shangdan suture, as constrained by some evidence, accreted only the South Qinling orogen to the southern part (ie, the North Qinling) of the North China block Contemporaneous rifting of the South China block and subsequent drifting separated the South Qinling from the South China block during the middle to late Paleozoic The separation of the South from the North China blocks is supported by other evidence, in particular, geomagnetic data Evidently it was the Late Triassic collision of the South China block with the South Qinling orogen along the Mianlue suture that led to final integration of the North and South China blocks
591 citations
TL;DR: It is reported that the secreted protein Slit repels neuronal precursors migrating from the anterior subventricular zone in the telencephalon to the olfactory bulb, providing a direct demonstration of a molecular cue whose concentration gradient guides the direction of migrating neurons.
Abstract: Although cell migration is crucial for neural development, molecular mechanisms guiding neuronal migration have remained unclear. Here we report that the secreted protein Slit repels neuronal precursors migrating from the anterior subventricular zone in the telencephalon to the olfactory bulb. Our results provide a direct demonstration of a molecular cue whose concentration gradient guides the direction of migrating neurons. They also support a common guidance mechanism for axon projection and neuronal migration and suggest that Slit may provide a molecular tool with potential therapeutic applications in controlling and directing cell migration.
541 citations
TL;DR: In this article, the specific heat and thermal conductivity of aligned carbon multiwall nanotubes (MWNTs) have been measured as a rolled-up version of graphene sheets, and a MWNT of a few tens nm diameter is found to demonstrate a strikingly linear temperature-dependent specific heat over the entire temperature range measured (10-300 K).
Abstract: The specific heat and thermal conductivity of millimeter-long aligned carbon multiwall nanotubes (MWNT's) have been measured. As a rolled-up version of graphene sheets, a MWNT of a few tens nm diameter is found to demonstrate a strikingly linear temperature-dependent specific heat over the entire temperature range measured (10--300 K). The results indicate that interwall coupling in MWNT's is rather weak compared with its parent form, graphite, so that one can treat a MWNT as a few decoupled two-dimensional single wall tubules. The thermal conductivity is found to be low, indicating the existence of substantial amounts of defects in the MWNT's prepared by a chemical-vapor-deposition method.
Journal Article•
TL;DR: The isolation of vertebrate homologs of the Drosophila slit gene are reported and it is shown that Slit protein binds to the transmembrane protein Roundabout (Robo), establishing a ligand-receptor relationship between two molecules important for neural development and suggesting a role for Slit in olfactory bulb axon guidance.
TL;DR: The crystallization process and crystal morphology of poly(ethylene terephathalate) (PET) -clay nanoscale composites prepared by intercalation, followed by in-situ polymerization, have been investigated by scanning electronic microscopy (SEM), TEM, dynamic scanning calorimetry (DSC), and X-ray techniques, together with mechanical methods.
Abstract: The crystallization process and crystal morphology of poly(ethylene terephathalate) (PET)–clay nanoscale composites prepared by intercalation, followed by in-situ polymerization, have been investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), dynamic scanning calorimetry (DSC), and X-ray techniques, together with mechanical methods. Results of the nonisothermal crystallization dynamics show that the nanocomposites of PET (Nano-PET) have 3 times greater crystallization rate than that of pure PET. The thermal properties of Nano-PET showed heat distortion temperature (HDT) 20–50°C higher than the pure PET, while with a clay content of 5%, the modulus of Nano-PET is as much as 3 times that of pure PET. Statistical results of particle distribution show that the average nanoscale size ranges from 10 to 100 nm. The particles are homogenously distributed with their size percentages in normal distribution. The agglomerated particles are 4% or so with some particles size in the micrometer scale. The morphology of exfoliated clay particles are in a diordered state, in which the morphology of the PET spherulitics are not easy to detect in most of microdomains compared with the pure PET. The molecular chains intercalated in the interlamellae of clay are confined to some extent, which will explain the narrow distribution of the Nano-PET molecular weight. The stripe-belt morphology of the intercalated clay show that polymer PET molecular chains are intercalated into the enlarged interlamellar space. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1139–1146, 1999
TL;DR: In this paper, Zhang et al. investigated the impact of El Nino on the precipitation in China for different seasons and found that negative precipitation anomalies appear in both southern and northern parts of China, while in between around the lower reaches of the Yangtze River and the Huaihe River valleys the precipitation anomalies tend to be positive.
Abstract: The impact of El Nino on the precipitation in China for different seasons are investigated diagnostically. It is found that El Nino can influence the precipitation in China significantly during its mature phase. In the Northern winter, spring and autumn, the positive precipitation anomalies are found in the southern part of China during the El Nino mature phase. In the Northern summer, the patterns of the precipitation anomalies in the El Nino mature phase are different from those in the other seasons. The negative precipitation anomalies appear in both southern and northern parts of China, while in between around the lower reaches of the Yangtze River and the Huaihe River valleys the precipitation anomalies tend to be positive. In the Northern winter, spring and autumn, the physical process by which El Nino affects the precipitation in the southern part of China can be explained by the features of the circulation anomalies over East Asia during the El Nino mature phase (Zhang et al., 1996). The appearance of an anticyclonic anomaly to the north of the maritime continent in the lower troposphere during the El Nino mature phase intensifies the subtropical high in the western Pacific and makes it shift westward. The associated southwesterly flow is responsible for the positive precipitation anomalies in the southern part of China. In the Northern summer, the intensified western Pacific subtropical high covers the southeastern periphery of China so that the precipitation there becomes less. In addition, the weakening of the Indian monsoon provides less moisture inflow to the northern part of China.
TL;DR: It is revealed that the EE genome species is most closely related to the DD genome progenitor that gave rise to the CCDD genome, and that the AA genome lineage, which contains cultivated rice, is a recently diverged and rapidly radiated lineage within the rice genus.
Abstract: The rice genus, Oryza, which comprises 23 species and 9 recognized genome types, represents an enormous gene pool for genetic improvement of rice cultivars. Clarification of phylogenetic relationships of rice genomes is critical for effective utilization of the wild rice germ plasm. By generating and comparing two nuclear gene (Adh1 and Adh2) trees and a chloroplast gene (matK) tree of all rice species, phylogenetic relationships among the rice genomes were inferred. Origins of the allotetraploid species, which constitute more than one-third of rice species diversity, were reconstructed based on the Adh gene phylogenies. Genome types of the maternal parents of allotetraploid species were determined based on the matK gene tree. The phylogenetic reconstruction largely supports the previous recognition of rice genomes. It further revealed that the EE genome species is most closely related to the DD genome progenitor that gave rise to the CCDD genome. Three species of the CCDD genome may have originated through a single hybridization event, and their maternal parent had the CC genome. The BBCC genome species had different origins, and their maternal parents had either a BB or CC genome. An additional genome type, HHKK, was recognized for Oryza schlechteri and Porteresia coarctata, suggesting that P. coarctata is an Oryza species. The AA genome lineage, which contains cultivated rice, is a recently diverged and rapidly radiated lineage within the rice genus.
TL;DR: The observation that the Dvl‐binding domain of either Frat1 or Axin was able to inhibit Wnt‐1‐induced LEF‐1 activation suggests that the interactions between Dvl and Axin and between DVL and Frat may be important for this signaling pathway.
Abstract: Wnt proteins transduce their signals through dishevelled (Dvl) proteins to inhibit glycogen synthase kinase 3beta (GSK), leading to the accumulation of cytosolic beta-catenin and activation of TCF/LEF-1 transcription factors. To understand the mechanism by which Dvl acts through GSK to regulate LEF-1, we investigated the roles of Axin and Frat1 in Wnt-mediated activation of LEF-1 in mammalian cells. We found that Dvl interacts with Axin and with Frat1, both of which interact with GSK. Similarly, the Frat1 homolog GBP binds Xenopus Dishevelled in an interaction that requires GSK. We also found that Dvl, Axin and GSK can form a ternary complex bridged by Axin, and that Frat1 can be recruited into this complex probably by Dvl. The observation that the Dvl-binding domain of either Frat1 or Axin was able to inhibit Wnt-1-induced LEF-1 activation suggests that the interactions between Dvl and Axin and between Dvl and Frat may be important for this signaling pathway. Furthermore, Wnt-1 appeared to promote the disintegration of the Frat1-Dvl-GSK-Axin complex, resulting in the dissociation of GSK from Axin. Thus, formation of the quaternary complex may be an important step in Wnt signaling, by which Dvl recruits Frat1, leading to Frat1-mediated dissociation of GSK from Axin.
TL;DR: This pattern indicates that the first settlement of modern humans in eastern Asia occurred in mainland Southeast Asia during the last Ice Age, coinciding with the absence of human fossils in easternAsia, 50,000-100,000 years ago.
Abstract: Summary The timing and nature of the arrival and the subsequent expansion of modern humans into eastern Asia remains controversial. Using Y-chromosome biallelic markers, we investigated the ancient human-migration patterns in eastern Asia. Our data indicate that southern populations in eastern Asia are much more polymorphic than northern populations, which have only a subset of the southern haplotypes. This pattern indicates that the first settlement of modern humans in eastern Asia occurred in mainland Southeast Asia during the last Ice Age, coinciding with the absence of human fossils in eastern Asia, 50,000–100,000 years ago. After the initial peopling, a great northward migration extended into northern China and Siberia.
TL;DR: The results of this dating study indicate that the lower Yixian fossil horizons are not Jurassic but rather are at least 20 Myr younger, placing them within middle Early Cretaceous time.
Abstract: The ancient lake beds of the lower part of the Yixian Formation, Liaoning Province, northeastern China, have yielded a wide rangeof well-preserved fossils: the ‘feathered’ dinosaurs Sinosauropteryx1, Protarchaeopteryx and Caudipteryx2, the primitive birds Confuciusornis3 and Liaoningornis4, the mammal Zhangheotherium5 and the reportedly oldest flowering plant, Archaefructus6. Equally well preserved in the lake beds are a wide range of fossil plants, insects, bivalves, conchostracans, ostracods, gastropods, fish, salamanders, turtles, lizards, the frog Callobatrachus7 and the pterosaur Eosipterus1,8. This uniquely preserved assemblage of fossils is providing newinsight into long-lived controversies over bird–dinosaur relationships1,2, the early diversification of birds3,9,10 and the origin and evolution of flowering plants6. Despite the importance of this fossil assemblage, estimates of its geological age have varied widely from the Late Jurassic to the Early Cretaceous. Here we present the first 40Ar/39Ar dates unambiguously associated with the main fossil horizons of the lower part of the Yixian Formation, and thus, for the first time, provide accurate age calibration of this important fauna. The results of this dating study indicate that the lower Yixian fossil horizons are not Jurassic but rather are at least 20 Myr younger, placing them within middle Early Cretaceous time.
TL;DR: The discovery of two distinct types of agnathan from the Lower Cambrian Chengjiang fossil-Lagerstätte imply that the first agnathans may have evolved in the earliest Cambrian, with the chordates arising from more primitive deuterostomes in Ediacaran times (latest Neoproterozoic, ∼555 Myr BP), if not earlier.
Abstract: The first fossil chordates are found in deposits from the Cambrian period (545–490 million years ago), but their earliest record is exceptionally sporadic and is often controversial. Accordingly, it has been difficult to construct a coherent phylogenetic synthesis for the basal chordates. Until now, the available soft-bodied remains have consisted almost entirely of cephalochordate-like animals from Burgess Shale-type faunas. Definite examples of agnathan fish do not occur until the Lower Ordovician (∼475 Myr BP), with a more questionable record extending into the Cambrian. The discovery of two distinct types of agnathan from the Lower Cambrian Chengjiang fossil-Lagerstatte is, therefore, a very significant extension of their range. One form is lamprey-like, whereas the other is closer to the more primitive hagfish. These finds imply that the first agnathans may have evolved in the earliest Cambrian, with the chordates arising from more primitive deuterostomes in Ediacaran times (latest Neoproterozoic, ∼555 Myr BP), if not earlier.
TL;DR: In this article, an ultrasonic shot peening (USSP) technique was used to construct a nanocrystalline surface layer on a pure Fe plate by using an X-ray diffraction (XRD) and transmission electron microscope (TEM).
TL;DR: In this article, the age of Bendong granodiorite and Sanfang and Yuanbaoshan granites was determined by both SHRIMP and conventional dating methods.
TL;DR: A 305m-thick loess-red clay sequence was discovered recently at Lingtai, which is located in the middle part of the Chinese Loess Plateau as discussed by the authors.
Max Planck Society1, Centre national de la recherche scientifique2, University of Oregon3, Florida Institute of Technology4, Potsdam Institute for Climate Impact Research5, Stockholm University6, University of Amsterdam7, Australian National University8, University of Bergen9, Hokkaido University10, Lamont–Doherty Earth Observatory11, Chinese Academy of Sciences12
TL;DR: In this paper, the reliability of the data was evaluated using explicit criteria and some types of data were re-analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month (MTCO), mean annual temperature (MAT), plant available moisture (PAM), and runoff (P-E).
Abstract: Palaeodata in synthesis form are needed as benchmarks for the Palaeoclimate Modelling Intercomparison Project (PMIP). Advances since the last synthesis of terrestrial palaeodata from the last glacial maximum (LGM) call for a new evaluation, especially of data from the tropics. Here pollen, plant-macrofossil, lake-level, noble gas (from groundwater) and δ18O (from speleothems) data are compiled for 18±2 ka (14C), 32 °N–33 °S. The reliability of the data was evaluated using explicit criteria and some types of data were re-analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month (MTCO), mean annual temperature (MAT), plant available moisture (PAM) and runoff (P-E). Cold-month temperature (MAT) anomalies from plant data range from −1 to −2 K near sea level in Indonesia and the S Pacific, through −6 to −8 K at many high-elevation sites to −8 to −15 K in S China and the SE USA. MAT anomalies from groundwater or speleothems seem more uniform (−4 to −6 K), but the data are as yet sparse; a clear divergence between MAT and cold-month estimates from the same region is seen only in the SE USA, where cold-air advection is expected to have enhanced cooling in winter. Regression of all cold-month anomalies against site elevation yielded an estimated average cooling of −2.5 to −3 K at modern sea level, increasing to ≈−6 K by 3000 m. However, Neotropical sites showed larger than the average sea-level cooling (−5 to −6 K) and a non-significant elevation effect, whereas W and S Pacific sites showed much less sea-level cooling (−1 K) and a stronger elevation effect. These findings support the inference that tropical sea-surface temperatures (SSTs) were lower than the CLIMAP estimates, but they limit the plausible average tropical sea-surface cooling, and they support the existence of CLIMAP-like geographic patterns in SST anomalies. Trends of PAM and lake levels indicate wet LGM conditions in the W USA, and at the highest elevations, with generally dry conditions elsewhere. These results suggest a colder-than-present ocean surface producing a weaker hydrological cycle, more arid continents, and arguably steeper-than-present terrestrial lapse rates. Such linkages are supported by recent observations on freezing-level height and tropical SSTs; moreover, simulations of “greenhouse” and LGM climates point to several possible feedback processes by which low-level temperature anomalies might be amplified aloft.
TL;DR: The authors compared the proportions of nouns and verbs in the early vocabularies of 24 English and 24 Mandarin-speaking toddlers (M age 5 20 months) and their mothers.
Abstract: Recently, researchers have been debating whether children exhibit a universal “noun bias” when learning a first language. The present study compares the proportions of nouns and verbs in the early vocabularies of 24 English- and 24 Mandarin-speaking toddlers ( M age 5 20 months) and their mothers. Three different methods were used to measure the proportion of noun types, relative to verb types: controlled observations in three contexts (book reading, mechanical toy play, regular toy play), identical across languages; a vocabulary checklist (MacArthur Communicative Development Inventory); and mothers’ reporting of their children’s “first words.” Across all measures, Mandarin-speaking children were found to have relatively fewer nouns and more verbs than English-speaking children. However, context itself played an important role in the proportions of nouns found in children’s vocabularies, such that, regardless of the language spoken, children’s vocabularies appeared dominated by nouns when they were engaged in book reading, but not when they were playing with toys. Mothers’ speech to children showed the same language differences (relatively more verbs in Mandarin), although both Mandarin- and English-speaking mothers produced relatively more verbs than their children. In sum, whether or not language-learning toddlers demonstrate a “noun bias” depends on a variety of factors, including the methods by which their vocabularies are sampled and the contexts in which observations occur.
TL;DR: It is proved that this Steiner tree problem with minimum number of Steiner points and bounded edge-length is NP-complete and a polynomial time approximation algorithm is presented whose worst-case performance ratio is 5.
TL;DR: In this article, the authors examined the multiseasonal irrigation experiments in four locations of the piedmont and lowland in the region, and developed crop water-stress sensitivity index, relationship between seasonal evapotranspiration (ET) and yield, and crop water production functions.
Abstract: Limited precipitation restricts yield of winter wheat (Triticum aestivum L.) grown in the North China Plain. Water stress effects on yield can be avoided or minimized by application of irrigation. We examined the multiseasonal irrigation experiments in four locations of the piedmont and lowland in the region, and developed crop water-stress sensitivity index, relationship between seasonal evapotranspiration (ET) and yield, and crop water production functions. By relating relative yield to relative ET deficit, we found that the crop was more sensitive to water stress from stem elongation to heading and from heading to milking. For limited irrigation, irrigation is recommended during the stages sensitive to water stress. Grain yield was 258–322 g m−2 in the piedmont and 260–280 g m−2 in the lowland under rainfed conditions. The corresponding seasonal ET was 242–264 mm in the piedmont and 247–281 mm in the lowland. Irrigation significantly increased seasonal ET and therefore grain yield as a result of increased kernel numbers per m−2 and kernels per ear. On average, one irrigation increased grain yield by 21–43% and two to four irrigations by 60–100%. Grain yield was linearly related to seasonal ET with a slope of 1.15 kg m−3 in the lowland and 1.73 kg m−3 in the piedmont. Water-use efficiency was 0.98–1.22 kg m−3 for rainfed wheat and 1.20–1.40 kg m−3 for the wheat irrigated 2–4 times. Grain yield response to the amount of irrigation (IRR) was developed using a quadratic function and used to analyze different irrigation scenarios. To achieve the maximum grain yield, IRR was 240 mm in the piedmont and 290 mm in the lowland. When the maximum net profit was achieved, IRR was 195 mm and 250 mm in the piedmont and lowland, respectively. The yield response curve to IRR showed a plateau over a large range of IRR, indicating a great potential in saving IRR while maintaining reasonable high levels of grain yield.
TL;DR: The genetic analysis of rice DH population derived from anther culture of an indica/japonica hybrid and molecular markers presented here may be useful in rice breeding for grain quality improvement.
Abstract: The inheritance of grain quality is more complicated than that of other agronomic traits in cereals due to epistasis, maternal and cytoplasmic effects, and the triploid nature of endosperm. In the present study, an established rice DH population derived from anther culture of an indica/japonica hybrid was used for genetic analysis of rice grain quality. A total of five parameters, amylose content (AC), alkali-spreading score (ASS), gel consistency (GC), percentage of grain with a white core (PGWC) and the square of the white core (SWC), were estimated for the DH lines and the parent varieties. For each parent, the value of each parameter was relatively stable in three locations, Beijing, Hangzhou and Chengdu, while the differences between the parents were significant for all five parameters. AC showed a bimodal distribution, and the distribution of ASS was skewed toward the value of JX17, while the other three parameters displayed continuous distributions among the DH lines with partially transgressive segregations. For AC, a minor and a major gene were found on chromosomes 5 and 6 respectively. The major gene, which should be an allele of wx, explained 91.9% of the total variation. For GC, two QTLs were identified on chromosomes 2 and 7 respectively. For ASS, a minor and a major gene were both located on chromosome 6. The major gene should be the same locus as the alkali degeneration gene (alk). Genetic linkage between alk and wx was found in QTL mapping. For PGWC, two QTLs were located on chromosomes 8 and 12. Only a minor QTL was found for SWC on chromosome 3. The results and the molecular markers presented here may be useful in rice breeding for grain quality improvement.
TL;DR: In this paper, a new linearized Crank?Nicolson-type scheme is presented by applying an extrapolation technique to the real coefficient of the nonlinear term in the GNLS equation.
TL;DR: In this paper, the pseudo-spin orbital potential (PSOP) was investigated in Zr and Sn isotopes from the proton drip line to the neutron drip line, and the PSOP depends on the derivative of the difference between the scalar and vector potentials dV/dr.
Abstract: Based on the Relativistic continuum Hartree-Bogoliubov (RCHB) theory, the pseudo-spin approximation in exotic nuclei is investigated in Zr and Sn isotopes from the proton drip line to the neutron drip line. The quality of the pseudo-spin approximation is shown to be connected with the competition between the centrifugal barrier (CB) and the pseudo-spin orbital potential ( PSOP ). The PSOP depends on the derivative of the difference between the scalar and vector potentials dV/dr. If dV/dr = 0, the pseudo-spin symmetry is exact. The pseudo-spin symmetry is found to be a good approximation for normal nuclei and to become much better for exotic nuclei with highly diffuse potential, which have dV/dr ∼ 0. The energy splitting of the pseudo-spin partners is smaller for orbitals near the Fermi surface ( even in the continuum ) than the deeply bound orbitals. The lower components of the Dirac wave functions for the pseudo-spin partners are very similar and almost equal in