Rapid Solidification of Undercooled Melts

Rapid solidification and microstructure evolution of deeply undercooled bulk concentrated Ni-20%at.Cu and Co-20%at.Pd alloys are strictly and systematically evaluated. First, thermodynamics of the undercooled melt is discussed. Consideration is provided for not only the systematic microstructure evolution within a broad undercooling range, but also the dendrite growth mechanism and the rapid solidification characteristics. The dendrite growth in the bulk undercooled melts was captured by a high speed camera. The first kind of grain refinement occurring in the low undercooling regimes was explained by a current grain refinement model. Besides for the dendrite melting mechanism, the stress originating from the solidification contraction and thermal strain in the first mushy zone during rapid solidification could be a main mechanism causing the second kind of grain refinement above the critical undercooling. This internal-stress led to the distortion and breakup of the primary dendrites and was semi-quantitatively described by a corrected stress accumulation model. It was found that the stress induced recrystallization could make the primary microstructures refine substantially after recalescence

Transcriptomics-based analysis of genes related to lead stress and their expression in the roots of Pogonatherum crinitum

Revealing plants’ tolerance and transport genes to heavy metal stress play an important role in exploring the potential of phytoremediation. Taking the heavy metal lead (Pb) hyperaccumulator plant Pogonatherum crinitum (Thunb.) Kunth as the research object, a hydroponic simulation stress experiment was set up to determine the physiological indicators such as antioxidant enzymes and non-enzymatic antioxidants in the roots of P. crinitum under different Pb concentrations (0, 300, 500, 1000, 2000 mg·L-1). RNA-Seq was performed, the Unigenes obtained by transcriptome sequencing were enriched and annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, and the differential expression genes (DEGs) of root were screened and verified by quantitative real-time polymerase chain reaction (qRT-PCR). The results are as follows: with the increase of Pb concentration, superoxide dismutase (SOD), catalase (CAT), and ascorbic acid (AsA) content increased. Peroxidase (POD), malondialdehyde (MDA), and ascorbic acid–glutathione (AsA-GSH) cycles showed low promotion with high inhibition. A total of 38.21 Gb of bases were obtained by transcriptome sequencing, and the base quality of each sample reached Q20 and Q30, accounting for 90%, making the sequencing results reliable. Combined with transcriptome sequencing, functional annotation, and qRT-PCR validation results, 17 root Pb-tolerant genes of P. crinitum were screened out, which were related to antioxidation, transportation, and transcription functions. Moreover, qRT-PCR verification results under different Pb stress concentrations were consistent with the transcriptome sequencing results and changes in physiological indicators. In brief, the root of P. crinitum can adapt to the Pb stress environment by up-regulating the expression of related genes to regulate the physiological characteristics

Link between Energy Investment in Biosynthesis and Proteostasis: Testing the Cost–Quality Hypothesis in Insects

The Energy Requirement for Biosynthesis Plays an Important Role in an Organism\u27s Life History, as It Determines Growth Rate, and Tradeoffs with the Investment in Somatic Maintenance. This Energetic Trait is Different between Painted Lady (Vanessa Cardui) and Turkestan Cockroach (Blatta Lateralis) Due to the Different Life Histories. Butterfly Caterpillars (Holometabolous) Grow 30-Fold Faster, and the Energy Cost of Biosynthesis is 20 Times Cheaper, Compared to Cockroach Nymphs (Hemimetabolous). We Hypothesize that Physiologically the Difference in the Energy Cost is Partially Attributed to the Differences in Protein Retention and Turnover Rate: Species with Higher Energy Cost May Have a Lower Tolerance to Errors in Newly Synthesized Protein. Newly Synthesized Proteins with Errors Are Quickly Unfolded and Refolded, And/or Degraded and Resynthesized Via the Proteasomal System. Thus, Much Protein Output May Be Given over to Replacement of the Degraded New Proteins, So the overall Energy Cost on Biosynthesis is High. Consequently, the Species with a Higher Energy Cost for Biosyntheses Has Better Proteostasis and Cellular Resistance to Stress. Our Study Found that, Compared to Painted Lady Caterpillars, the Midgut Tissue of Cockroach Nymphs Has Better Cellular Viability under Oxidative Stresses, Higher Activities of Proteasome 20S, and a Higher RNA/growth Ratio, Supporting Our Hypothesis. This Comparative Study Offers a Departure Point for Better Understanding Life History Tradeoffs between Somatic Maintenance and Biosynthesis

RPN: A Word Vector Level Data Augmentation Algorithm in Deep Learning for Language Understanding

This paper presents a new data augmentation algorithm for natural understanding tasks, called RPN:Random Position Noise algorithm.Due to the relative paucity of current text augmentation methods. Few of the extant methods apply to natural language understanding tasks for all sentence-level tasks.RPN applies the traditional augmentation on the original text to the word vector level. The RPN algorithm makes a substitution in one or several dimensions of some word vectors. As a result, the RPN can introduce a certain degree of perturbation to the sample and can adjust the range of perturbation on different tasks. The augmented samples are then used to give the model training.This makes the model more robust. In subsequent experiments, we found that adding RPN to the training or fine-tuning model resulted in a stable boost on all 8 natural language processing tasks, including TweetEval, CoLA, and SST-2 datasets, and more significant improvements than other data augmentation algorithms.The RPN algorithm applies to all sentence-level tasks for language understanding and is used in any deep learning model with a word embedding layer.Comment: 10 pages, 4 figure

Provenance of late Paleozoic strata in the Yili Basin : implications for tectonic evolution of the South Tianshan orogenic belt

This research was supported by the 973 Program under grant no. 2015CB453000, the National Natural Science Foundation of China (41502109), the Cultivating Program of Middle-Aged Key Teachers of Chengdu University of Technology (KYGG201718), Innovation Team of Sedimentary Geology of Chengdu University of Technology (KYTD201703), and by the China Postdoctoral Science Foundation (2015M582528). Cawood acknowledges support from the Australian Research Council grant FL160100168.The Yili Basin in NW China preserves a late Paleozoic volcano-sedimentary succession, the provenance of which helps to constrain the tectonic evolution of the South Tianshan orogenic belt. U-Pb ages and trace-element and Hf isotopic compositions of detrital zircons from the Late Devonian to earliest early Carboniferous strata in the Yili Basin suggest that the unit contains detritus mainly derived from basement rocks and contemporaneous arc-related volcanic rocks. The age of the unconformable contact between the Dongtujinhe Formation and underlying arc-related volcanic rocks is constrained to ca. 310 Ma. This age is consistent with published data for tectonic exhumation of high- to ultrahigh-pressure ([U]HP) metamorphic rocks from the northern margin of the South Tianshan orogenic belt. Zircon U-Pb ages from the sedimentary rocks, including clasts in conglomerate, indicate that detritus of the Dongtujinhe Formation was derived from multiple sources related to uplift and erosion of the southern Yili-Central Tianshan block. The presence of abundant eclogite clasts in the conglomerate of the Keguqinshan Formation indicates that (U)HP metamorphic rocks in the South Tianshan orogenic belt were exposed and supplied detritus to the southern Yili Basin at ca. 300 Ma. The early Middle Permian clastic rocks are characterized by Early Permian detrital zircons with a single peak at 278 Ma, derived from the postcollision magmatic rocks. During the Late Permian, input of detritus from old volcanic-sedimentary rocks and basement progressively increased. Integration of the provenance data from late Paleozoic strata in the Yili Basin with the time-equivalent northern Tarim and South Tianshan regions provides a record of the northward subduction of the South Tianshan oceanic crust beneath the Yili-Central Tianshan block in the Late Devonian to late Carboniferous (380-310 Ma), followed by continent-continent collision and final amalgamation at ca. 310-300 Ma, with postcollisional extension in the Permian.Publisher PDFPeer reviewe

Strength and size of phosphorus-rich patches determine the foraging strategy of Neyraudia reynaudiana

BackgroundUnder natural conditions, soil nutrients are heterogeneously distributed, and plants have developed adaptation strategies to efficiently forage patchily distributed nutrient. Most previous studies examined either patch strength or patch size separately and focused mainly on root morphological plasticity (increased root proliferation in nutrient-rich patch), thus the effects of both patch strength and size on morphological and physiological plasticity are not well understood. In this study, we examined the foraging strategy of Neyraudia reynaudiana (Kunth) Keng ex Hithc, a pioneer grass colonizing degraded sites, with respect to patch strength and size in heterogeneously distributed phosphorus (P), and how foraging patchily distributed P affects total plant biomass production. Plants were grown in sand-culture pots divided into 1/2, 1/4, 1/6 compartments and full size and supplied with 0+0/30, 0+7.5/30 and 7.5+0/30mg P/kg dry soil as KH2PO4 or 0+15/15, 0+18.5/ 18.5, 7.5+15/15mgkg-1 in the homogenous treatment. The first amount was the P concentration in the central region, and that the second amount was the P concentration in the outer parts of the pot.ResultsAfter 3months of growth under experimental conditions, significantly (p<0.05) high root elongation, root surface area, root volume and average root diameter was observed in large patches with high patch strength. Roots absorbed significantly more P in P-replete than P-deficient patches. Whole plant biomass production was significantly higher in larger patches with high patch strength than small patches and homogeneous P distribution.ConclusionThe result demonstrates that root morphological and physiological plasticity are important adaptive strategies for foraging patchily distributed P and the former is largely determined by patch strength and size. The results also establish that foraging patchily distributed P resulted in increased total plant biomass production compared to homogeneous P distribution

Preparation and characterization of PLA ultrasound contrast agents by combining an ultrasound method and a Shirasu Porous Glass (SPG) membrane emulsification technique

The ultrasound contrast agent based on a poly lactic acid (PLA) was prepared by combining an ultrasound method and a Shirasu Porous Glass (SPG) membrane emulsification technique. An aqueous phase containing ammonium bicarbonate was used as the internal water phase (WO, and PLA and Span 80 were dissolved in a solvent of dichloromethane (DCM), which was used as the oil phase (0). These two solutions were probe sonicated to form a W(1)/O primary emulstion. The primary emulsion was permeated through the uniform pores (1.1 mu m) of an SPG membrane into the external water phase (W(2)) by the pressure of nitrogen gas to form the uiniform W(1)/O/W(2) droplets. After DCM was evaporated, the hardened PLA microcapsules were further formulated into a lyophilized powder containing decafluorobutane gas. SEM image demonstrated that the PLA microcapsules were sphere-shaped and internally hollow with an average diameter ranging from 1.99 to 3.58 mu m. In vitro, the PLA contrast agents showed high acoustic enhancement properties, the enhancement increased nonlinearly with dose, and the minimal loss (less than 5 dB) of signal was observed over 20 min of analysis at 37 degrees C, the maximum acoustic enhancement was 45 dB, which significantly higher (p<0.01) compared to a value of 28 dB for those prepared by a conventional solvent evaporation method. In conclusion, the hollow PLA microcapsules prepared by the novel method have the characteristics desirable for an intravenously administered ultrasound contrast agents