Diversity and conservation of Chinese wild begonias

Begonia, one of the most diverse plant taxa and the fifth or sixth largest angiosperm genus, consists of over1800 accepted species. The number of species recognized within this genus has greatly increased over the past 20 years, rising from 80 to 200 species in China alone. Based on recent field surveys, the number of begonia species in China is predicted to be between 250 and 300. Given the large number of begonia species that still remain to be described, further taxonomical work is urgently required. This is especially true for Chinese Begonia, in which there is a huge diversity of habitat, habit, plant size, leaf type, flower and fruit morphology, and most species are narrowly distributed in isolated habitats that are subject to negative disturbances from climate change, as well as agricultural and industrial activities. Although the conservation status for the majority of species has been evaluated using the standards of the International Union for Conservation of Nature, the results don't represent the truth in many species, and also about11.5% of which are data-absent. In addition, illegal collection and over-harvesting of wild begonias for ornamental or medicinal use has increased due to the rapid development of internet commerce. Far more often than predicted, these species should be categorized as rare and endangered and require immediate protection. Ex situ conservation of Chinese begonias started in 1995 and over 60% of the total species have been so far introduced into cultivation by several major botanical gardens in China. However, only few research institutions, limited funds and human resources have been involved in Begonia conservation;moreover, no project has conducted reintroduction. Therefore, more conservation-based work remains to be done. Improved conservation of Chinese begonias in the future depends on further field survey, an improved understanding of population diversity, and integrative approaches, including in situ and ex situ conservation, seed banking, and plant reintroduction. Species-targeted conservation zones should be established for endangered species excluded from the existing nature reserves. Additionally, laws pertaining to plant protection should be extended to prevent the illegal collection and transaction of wild plants, particularly for those species with unique habitats and small populations.

Comparative analysis of mitochondrial genome of a deepsea crab Chaceon granulates reveals positive selection and novel genetic features

Deep-sea organisms survive in an extremely harsh environment.There must be some genetic adaptation mechanisms for them.We systematically characterized and compared the complete mitochondrial genome(mitogenome)of a deep-sea crab(Chaceon granulates)with those of shallow crabs.The mitogenome of the crab was 16126 bp in length,and encoded 37 genes as most of a metazoan mitogenome,including 13 protein-coding genes(PCGs),22 transfer RNA(tRNA)genes,and 2 ribosomal RNA(rRNA)genes.The gene arrangement and orientation was conserved in the crabs.However,a unique mitogenome element regulator,the origin of light-strand replication(O L),was firstly predicted in the present crab mitogenome.In addition,further positive selection analysis showed that two residues(33 S in ND3 and 502 I in ND5)in C.granulates mitogenome were positively selected,indicated the selective evolution of the deep-sea crab.Therefore,the mitogenome of deep-sea C.granulates showed a unique OL element and positive selection.These special features would influence the mitochondrial energy metabolism,and be involved in the adaptation of deepsea environment,such as oxygen deficits and low temperatures.

Estimating Fraction of Photosynthetically Active Radiation of Corn with Vegetation Indices and Neural Network from Hyperspectral Data

The fraction of photosynthetically active radiation （FPAR） is a key variable in the assessment of vegetation productivity and land ecosystem carbon cycles. Based on ground-measured corn hyperspectral reflectance and FPAR data over Northeast China, the correlations between corn-canopy FPAR and hyperspectral reflectance were analyzed, and the FPAR estimation performances using vegetation index （VI） and neural network （NN） methods with different two-band-combination hyperspectral reflectance were investigated. The results indicated that the corn-canopy FPAR retained almost a constant value in an entire day. The negative correlations between FPAR and visible and shortwave infrared reflectance （SWIR） bands are stronger than the positive correlations between FPAR and near-infrared band re- flectance （NIR）. For the six VIs, the normalized difference vegetation index （NDVI） and simple ratio （SR） performed best for estimating corn FPAR （the maximum R2 of 0.8849 and 0.8852, respectively）. However, the NN method esti- mated results （the maximum Rz is 0.9417） were obviously better than all of the VIs. For NN method, the two-band combinations showing the best corn FPAR estimation performances were from the NIR and visible bands; for VIs, however, they were from the SWIR and NIR bands. As for both the methods, the SWIR band performed exceptionally well for corn FPAR estimation. This may be attributable to the fact that the reflectance of the SWIR band were strongly controlled by leaf water content, which is a key component of corn photosynthesis and greatly affects the absorption of photosynthetically active radiation （APAR）, and makes further impact on corn-canopy FPAR.

Biosorption of Metal Ions by Exopolysaccharide Produced by <i>Azotobacter chroococcum</i>XU1

This paper deals with adsorption of Pb and Hg on the exopolysaccharide produced by Azotobacter chroococcum XU1. The adsorption of metal ions was significantly affected by the pH of metal solutions (Pb(NO3)2 and Hg(NO3)2), metal ions concentration and exopolysaccharide concentrations. At optimum pH the uptakes of the metals were 40.48% and 47.87% respectively. The metal ions biosorption was high at 4, 5-5.

Redox Controllable Switch of Crystalline Phase and Physical Property in SrVO_x Epitaxial Films

Transition-metal oxides have attracted much attention due to its abundant crystalline phases and intriguing physical properties. However, some of these compounds are difficult to be fabricated directly in film form due to the ease of valence variation of transition-metal elements.In this work, we reveal the reversible structural transition between SrVO3 and Sr2V2O7 films via thermal treatment in oxygen atmosphere or in vacuum. Based on this, Sr2V2O7 epitaxial films are successfully synthesized and studied. Property characterizations show that the semitransparent and metallic SrVO3 could reversibly switch into transparent and insulating Sr2V2O7, implying potential applications in controllable electronic and optical devices.

Van der Waals Epitaxy of Anatase TiO2 on mica and Its Application as Buffer Layer

MICAtronics, based on the functional oxide/mica heterostructures, has recently attracted much attention due to its potential applications in transparent, flexible electronics and devices. However, the weak van der Waals interaction decreases the tolerable lattice mismatch and thus limits the species of function oxides that are able to be epitaxially grown on mica. We successfully fabricate relatively high-quality epitaxial anatase TiO2 thin films on mica substrates. Structural analyses reveal that the carefully chosen growth temperature(650℃) and suitable crystalline phase(anatase phase) of TiO2 are the key issues for this van der Waals epitaxy. Moreover, as a buffer layer, the TiO2 layer successfully suppresses the decomposition of BiFeO3 and the difficulty of epitaxial growth of BiFeO3 is decreased. Therefore, relatively high-quality anatase TiO2 is proved to be an effective buffer layer for fabricating more functional oxides on mica.

A New Era of Sci-Tech Innovation

JUST before the 19th National Congress of the Communist Party of China(CPC),on September 29,the world’s first trunk line of quantum telecommunication–the Jing-Hu(BeijingShanghai)Trunk Line–opened,which is connected with the world’s first quantum satellite"Micius,"named after an ancient Chinese philosopher.

Literature classification and its applications in condensed matter physics and materials science by natural language processing

The exponential growth of literature is constraining researchers’access to comprehensive information in related fields.While natural language processing(NLP)may offer an effective solution to literature classification,it remains hindered by the lack of labelled dataset.In this article,we introduce a novel method for generating literature classification models through semi-supervised learning,which can generate labelled dataset iteratively with limited human input.We apply this method to train NLP models for classifying literatures related to several research directions,i.e.,battery,superconductor,topological material,and artificial intelligence(AI)in materials science.The trained NLP‘battery’model applied on a larger dataset different from the training and testing dataset can achieve F1 score of 0.738,which indicates the accuracy and reliability of this scheme.Furthermore,our approach demonstrates that even with insufficient data,the not-well-trained model in the first few cycles can identify the relationships among different research fields and facilitate the discovery and understanding of interdisciplinary directions.

Transposable elements at the center of the crossroads between embryogenesis, embryonic stem cells, reprogramming,and long non-coding RNAs

Transposable elements(TEs) are mobile genomic sequences of DNA capable of autonomous and nonautonomous duplication. TEs have been highly successful,and nearly half of the human genome now consists of various families of TEs. Originally thought to be non-functional,these elements have been co-opted by animal genomes to perform a variety of physiological functions ranging from TE-derived proteins acting directly in normal biological functions, to innovations in transcription factor logic and influence on epigenetic control of gene expression. During embryonic development, when the genome is epigenetically reprogrammed and DNA-demethylated, TEs are released from repression and show embryonic stage-specific expression, and in human and mouse embryos, intact TEderived endogenous viral particles can even be detected. Asimilar process occurs during the reprogramming of somatic cells to pluripotent cells: When the somatic DNA is demethylated, TEs are released from repression. In embryonic stem cells(ESCs), where DNA is hypomethylated, an elaborate system of epigenetic control is employed to suppress TEs, a system that often overlaps with normal epigenetic control of ESC gene expression. Finally, many long non-coding RNAs(lnc RNAs) involved in normal ESC function and those assisting or impairing reprogramming contain multiple TEs in their RNA. These TEs may act as regulatory units to recruit RNA-binding proteins and epigenetic modifiers. This review covers how TEs are interlinked with the epigenetic machinery and lnc RNAs, and how these links influence each other to modulate aspects of ESCs,embryogenesis, and somatic cell reprogramming.

New directions of digitally driven S&T evaluation

Science and Technology(S&T)evaluation plays a baton role in developing science and technology innovation.However,traditional S&T evaluation indicators and methods are difficult to apply effectively in S&T evaluation practice.This paper analyzes the transformation of the S&T evaluation paradigm in the digital environment.Theories,methods,and tools of S&T evaluation research are continuously innovated and optimized;big data becomes the driving force of S&T evaluation development;the role played by S&T evaluation is shifting from a provider of statistical data and information to a participant in S&T decision-making activities.S&T evaluation research should focus on improving data retrieval and organization,knowledge mining and knowledge discovery,and intelligent evaluation models.Moreover,we suggest that scientists carry out S&T evaluation in agreement with the needs of S&T development:1)monitoring and sensing the development of science and technology in real-time with the help of emerging digital technologies;2)exploring solutions to major concerns such as technical project management mechanisms,utilizing advanced data science and digital technologies to identify important scientific frontiers,and leveraging big data in science of science to reveal patterns and characteristics of scientific structures and activities;3)carrying out problem-oriented evaluation research practice focused on four aspects,including intelligent project evaluation,evaluation of the critical technology competitiveness,talent assessment,and diagnostic evaluation of the research entity competitiveness.

Calcium-tributylphosphine oxide passivation enables the efficiency of pure-blue perovskite light-emitting diode up to 3.3%

Metal halide perovskites are attractive for light-emitting diodes due to their superior optoelectronic properties such as tunable bandgaps,high photoluminescence quantum yields(PLQYs),high color purities and solution processability[1–6].In the past several years,impressive progress has been made in perovskite light-emitting diodes(PeLEDs)via microstructure engineering[7],charge balancing[8],surface defect passivation[9,10],metal ion doping[11,12]and dimensional engineering[13].As such,the green,red and near-infrared PeLEDs have achieved impressive external quantum efficiencies(EQEs)exceeding 20%[7,8,14,15].However,the performances of pure-blue PeLEDs,i.e.,brightness and EQEs,still lag largely behind those of the green and red counterparts,which severely impedes the PeLED application in full-color display and solid-state lighting.

Bio-inspired clay nanosheets/polymer matrix/mineral nanofibers ternary composite films with optimal balance of strength and toughness

Although remarkable progress has been witnessed in mimicking the nacre-like architecture in laboratory,it remains a great challenge for understanding the unique balancing mechanism of toughness and strength in biological materials. Here,taking advantage of the synergistic effect of different dimensional nanoscale building blocks,we fabricate nacre-like films that reconcile high strength and toughness.The obtained ternary lamellar composite films are constructed by one-dimensional xonotlite nanowires and two-dimensional montmorillonite nanosheets with the assistance of poly（vinyl alcohol）. The ternary composite films show high strength（（241.8±10.2）MPa） and toughness（（5.85±0.46） MJ m^-3）,both of which are higher than that of the single nanofibrillar xonotlite network films or the binary montmorillonite/poly（vinyl alcohol） composite films. The excellent mechanical properties of the nacre-like ternary composite films are aroused by the synergistic toughening mechanism of the different dimensional building blocks. This strategy provides a facile approach to integrate the nacre-like composite films with potential applications in tissue engineering scaffold,strong air barrier coatings,and fire-retardant packing materials.

Critical Behavior of Spatial Evolutionary Game with Altruistic to Spiteful Preferences on Two-Dimensional Lattices

Self-questioning mechanism which is similar to single spin-flip of Ising model in statistical physics is introduced into spatial evolutionary game model.We propose a game model with altruistic to spiteful preferences via weighted sums of own and opponent's payoffs.This game model can be transformed into Ising model with an external field.Both interaction between spins and the external field are determined by the elements of payoff matrix and the preference parameter.In the case of perfect rationality at zero social temperature,this game model has three different phases which are entirely cooperative phase,entirely non-cooperative phase and mixed phase.In the investigations of the game model with Monte Carlo simulation,two paths of payoff and preference parameters are taken.In one path,the system undergoes a discontinuous transition from cooperative phase to non-cooperative phase with the change of preference parameter.In another path,two continuous transitions appear one after another when system changes from cooperative phase to non-cooperative phase with the prefenrence parameter.The critical exponents ν,β,and γ of two continuous phase transitions are estimated by the finite-size scaling analysis.Both continuous phase transitions have the same critical exponents and they belong to the same universality class as the two-dimensional Ising model.

Hierarchically Switched Networks

The Internet of today is facing serious challenges including lack of routing system scalability, unpredictable network behavior, uncertainty of data packet paths, poor control and manageability, unachieved Quality of Service （QoS）, vulnerability of network facilities to Distributed Denial-of-Service （DD^S） attacks, core router complexity, costliness, and high power consumption. All of these defects have their root causes in the routing system. This paper first proposes a new network architecture which combines network typology with addressing. It then highlights that reliability of the tree structure is guaranteed by the concepts of logical node and logical link. Furthermore, shortcut link technology makes tree topology more flexible, and IP routing can be replaced with IP switching. As a result, all flaws in the current Internet architecture can be overcome.

A citation iteration method for publications and scientists evaluation

In the last decades many methods have been developed for the evaluation of the quality and impact of both the scientific research papers and scientists.Effectively identifying,discovering,and evaluating high-impact papers using scientometric methods,and adopting reasonable evaluation procedures and methods are vital to stimulating scientists’creative vitality.Examples of methods used for evaluating impact are:h-index and the cited frequency of articles and the number of highly cited papers.Here we propose a new method to assess the scientist impact based on citation iteration.The method was inspired in the Page Rank algorithm.In the present study,both the number of citations and the citing publications after each citation were considered.According to the obtained results,the proposal allows a more accurate measurement of the impact of scientific papers.Also,the application of this method,it can greatly improve the judgment efficiency of high-impact scientists.We have also conducted an empirical study at three levels in the discipline of mathematics,namely the comparisons of two publications,two scientists and eight scientists.Results show that indexes proposed in this dissertation designed for the publications’impacts evaluation and scientists’impact evaluation can be used to find the cause behind the number of cited frequencies resulting in the impact difference.The Q-index for publications’impacts evaluation and F-index for scientists’impacts evaluation proposed in this article can be used more accurately to check and evaluate the impact of scientists.Additionally,these new indexes can be used in the research management of departments at all levels,and can be useful by the states to find leading scientists in several fields.