Shortening the manufacturing process of degradable magnesium alloy minitube for vascular stents by introducing cyclic extrusion compression

Due to its excellent biocompatibility and biodegradability,Mg and its alloys are considered to be promising materials for manufacturing of vascular sent.However,the manufacture of high-precision and high-performance Mg alloys minitubes is still a worldwide problem with a long manufacturing processing caused by the poor workability of Mg alloys.To solve this problem,the cyclic extrusion compression(CEC)was used to pretreat the billet by improving the workability of Mg alloys,finally shortening the manufacturing process.After CEC treatment,the size of grains and second phase particles of Mg alloys were dramatically refined to 3.2μm and 0.3μm,respectively.Only after three passes of cold drawing,the wall thickness of minitube was reduced from 0.200 mm to 0.135 mm and a length was more than 1000 mm.The error of wall thickness was measured to be less than 0.01 mm,implying a high dimensional accuracy.The yield strength(YS),ultimate tensile strength(UTS)and elongation of finished minitube were 220±10 MPa,290±10 MPa and 22.0±0.5%,respectively.In addition,annealing can improve mechanical property and corrosion resistance of minitubes by improving the homogeneity of the microstructure and enhancing the density of basal texture.

The misalignment between degradation rate and mechanical integrity of Mg-Zn-Y-Nd alloy during the degradation evaluation in modified Hanks’solutions

The degradation behavior of biodegradable Mg alloys has become a research hotspot in the fields about biodegradable metallic materials.While the most of the related publications mainly focused on the degradation rate of Mg-based materials,but rare to care about the changes of their mechanical properties during the immersion period,which can significantly affect their service performance.The link between residual strength and Mg degradation is not appreciated enough.In this work,a series media were constructed based on Hanks’solution,the effects of inorganic ions on the degradation rate and mechanical integrity of Mg-Zn-Y-Nd alloy were investigated.The results indicated that the degradation behavior of Mg alloy was mainly controlled by degradation products and there is no direct correspondence between the degradation rate change and mechanical integrity of Mg alloy.The relevant findings are beneficial for selecting the monitoring index in Mg corrosion tests and evaluating the service reliability of Mg alloys for biomedical applications.

Reaction kinetics for the heterogeneously resin-catalyzed and homogeneously self-catalyzed esterification of thioglycolic acid with 2-ethyl-1-hexanol

Producing 2-ethyl-1-hexyl thioglycolate(ETE)via esterification reaction with thioglycolic acid(TGA)aqueous solution as raw material by reactive-separation coupling technology is a promising process intensification method.To choose suitable reactive-separation coupling strategy,the kinetic studies of the esterification of TGA with 2-ethyl-1-hexanol(EHL)were carried out in a batch system.The commercial ion exchange resin was employed as an eco-friendly catalyst.The effects of temperature,catalyst concentration and molar ratio were determined.It was interesting to observe that the equilibrium conversion of TGA increased with the increase of catalyst mass fraction due to the adsorption of product water onto resin surface.The activity-based pseudo-homogeneous(PH),Eley-Rideal(ER)and Langmuir-Hinshelwood-Ho ugen-Watson(LHHW)models were used to fit the kinetics data of the resin-catalyzed reaction.The models of ER and LHHW performed better than the PH model.The kinetics of the TGA-self-catalyzed reaction was also determined.An activity-based homogeneous kinetics model could well describe this self-catalyzed reaction.These results would be meaningful to the selection and design of an appropriate reactionseparation strategy for the production of ETE,to realize the process intensification.

Kinetics measurement of ethylene-carbonate synthesis via a fast transesterification by microreactors

High-purity ethylene carbonate(EC)is widely used as battery electrolyte,polycarbonate monomer,organic intermediate,and so on.An economical and sustainable route to synthesize high-purity ethylene carbonate(EC)via the transesterification of dimethyl carbonate(DMC)with ethylene glycol(EG)is provided in this work.However,this reaction is so fast that the reaction kinetics,which is essential for the industrial design,is hard to get by the traditional measuring method.In this work,an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst.The effects of flow rate,microreactor diameter,catalyst concentration,reaction temperature,and reactant molar ratio were investigated.An activity-based pseudohomogeneous kinetic model,which considered the non-ideal properties of reaction system,was established to describe the transesterification of DMC with EG.Detailed kinetics data were collected in the first 5 min.Using these data,the parameters of the kinetic model were correlated with the maximum average error of 11.19%.Using this kinetic model,the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%,suggesting its satisfactory prediction performance.

Effect of Rolling Temperature on the Mechanical Properties and Corrosion Behavior of Mg-Zn-Y-Nd Alloy Thin Sheets

There is a growing demand for degradable membranes with sufficient mechanical properties to guide tissue regeneration in dental surgery.In the present work,a two-stage rolling process in which the first rolling stage(FRS)adopted a reduction rate of 30%for six passes at various temperatures,while the second rolling stage was rolling at 200℃for two passes,was employed to prepare a 150μm-grade Mg-2.0Zn-0.5Y-0.5Nd(ZE21B)Mg alloy sheets for guided tissue regeneration membrane.The microstructure of the thin sheets was gradually refined with increasing rolling passes,and the thin sheets that were rolled at different FRS temperatures exhibit an ellipse texture.The thin sheets rolled at 350℃for FRS show low elongation due to premature fracture caused by the coarse second phase particles.On account of uniform and fine grains,the thin sheets rolled at 400℃for the FRS have proper mechanical properties:yield strength of 214.6±8.5 MPa,ultimate tensile strength(UTS)of 246.8±10.3 MPa and elongation to failure of 28.3±1.2%.When rolling at 450℃for FRS,proper ductility of the thin sheets has been acquired,followed by a decline in UTS since a bimodal structure with fine and coarse grain was developed.Immersion tests demonstrated the FRS temperature had no significant effect on the corrosion behavior and corrosion rate of Mg alloy sheets after 7 days’immersion in artificial saliva solution.This research has great significance for the production of degradable Mg sheets for guided tissue regeneration membrane.

Wireless sequential dual light delivery for programmed PDT in vivo

Using photodynamic therapy(PDT)to treat deep-seated cancers is limited due to inefficient delivery of photosensitizers and low tissue penetration of light.Polymeric nanocarriers are widely used for photosensitizer delivery,while the self-quenching of the encapsulated photosensitizers would impair the PDT efficacy.Furthermore,the generated short-lived reactive oxygen spieces(ROS)can hardly diffuse out of nanocarriers,resulting in low PDT efficacy.Therefore,a smart nanocarrier system which can be degraded by light,followed by photosensitizer activation can potentially overcome these limitations and enhance the PDT efficacy.A light-sensitive polymer nanocarrier encapsulating photosensitizer(RB-M)was synthesized.An implantable wireless dual wavelength microLED device which delivers the two light wavelengths sequentially was developed to programmatically control the release and activation of the loaded photosensitizer.Two transmitter coils with matching resonant frequencies allow activation of the connected LEDs to emit different wavelengths independently.Optimal irradiation time,dose,and RB-M concentration were determined using an agent-based digital simulation method.In vitro and in vivo validation experiments in an orthotopic rat liver hepatocellular carcinoma disease model confirmed that the nanocarrier rupture and sequential low dose light irradiation strategy resulted in successful PDT at reduced photosensitizer and irradiation dose,which is a clinically significant event that enhances treatment safety.

Ultra-broadband pulse generation via hollow-core fiber compression and frequency doubling for ultra-intense lasers

We demonstrate an ultra-broadband high temporal contrast infrared laser source based on cascaded optical parametric amplification,hollow-core fiber(HCF)and second harmonic generation processes.In this setup,the spectrum of an approximately 1.8μm laser pulse has near 1μm full bandwidth by employing an argon gas-filled HCF.Subsequently,after frequency doubling with cascaded crystals and dispersion compensation by a fused silica wedge pair,9.6 fs(~3cycles)and 150μJ pulses centered at 910 nm with full bandwidth of over 300 nm can be generated.The energy stability of the output laser pulse is excellent with 0.8%(root mean square)over 20 min,and the temporal contrast is>10^(12)at-10 ps before the main pulse.The excellent temporal and spatial characteristics and stability make this laser able to be used as a good seed source for ultra-intense and ultrafast laser systems.

Protein interaction networks:centrality,modularity,dynamics,and applications

In the post-genomic era,proteomics has achieved significant theoretical and practical advances with the development of high-throughput technologies.Especially the rapid accumulation of protein-protein interactions(PPIs)provides a foundation for constructing protein interaction networks(PINs),which can furnish a new perspective for understanding cellular organizations,processes,and functions at network level.In this paper,we present a comprehensive survey on three main characteristics of PINs:centrality,modularity,and dynamics.1)Different centrality measures,which are used to calculate the importance of proteins,are summarized based on the structural characteristics of PINs or on the basis of its integrated biological information;2)Different modularity definitions and various clustering algorithms for predicting protein complexes or identifying functional modules are introduced;3)The dynamics of proteins,PPIs and sub-networks are discussed,respectively.Finally,the main applications of PINs in the complex diseases are reviewed,and the challenges and future research directions are also discussed.

Femtosecond infrared optical vortex lasers based on optical parametric amplification

Infrared femtosecond optical vortices open up many new research fields,such as optical micro–nano manipulation,time-resolved nonlocal spectroscopy in solids,vortex secondary radiation and particle generations.In this article,we demonstrate a femtosecond optical vortex laser system based on a two-stage optical parametric amplifier.In our experiment,1.45µm vortex signal pulses with energy of 190µJ and 1.8µm vortex idler pulses with energy of 158µJ have been obtained,and the pulse durations are 51 and 48 fs,respectively.Both the energy fluctuations of the signal and idler pulses are less than 0.5%(root mean square),and the spectral fluctuations are less than 1.5%within 1 hour.This type of highly stable femtosecond optical vortex laser has a wide range of applications for vortex strong-field physics.

High temporal contrast 1053 nm laser source based on optical parametric amplification and second-harmonic generation

Temporal contrast directly affects the interaction between ultraintense and ultrashort pulse lasers with matter.Seed laser sources with broad bandwidth and high temporal contrast are significant for overall temporal contrast enhancement.The technique of cascaded nonlinear processes with optical parametric amplification and second-harmonic generation is demonstrated for high temporal contrast seed source generation.Within 40 ps before the main pulse,the temporal contrast reaches over 10^(11).The pulse energy and duration of the high-contrast pulse are 112μJ and 70 fs,respectively.Considering its high beam quality and stability,this laser source can serve as a high-quality seed for Nd:glass-based ultraintense and ultrashort pulse laser facilities.

13.4 fs,0.1 Hz OPCPA Front End for the 100 PW-Class Laser Facility

Here,we report the recent progress on the front end developed for the 100 PW-class laser facility.Using 3 stages of optical parametric chirped-pulse amplification(OPCPA)based on lithium triborate(LBO)crystals,we realized a 5.26 J/0.1 Hz amplified output with a bandwidth over 200 nm near the center wavelength of 925 nm.After the compressor,we obtained a pulse duration of 13.4 fs.As the compression efficiency reached 67%,this OPCPA front end could potentially support a peak power of 263 TW at a repetition rate of 0.1 Hz.To the best of our knowledge,among all the 100 TW-level OPCPA systems,it shows the widest spectral width,the shortest pulse duration,and it is also the first OPCPA system working at a repetition-rate mode.

Tailoring Texture to Highly Strengthen AZ31 Alloy Plate in the Thickness Direction via Pre-tension and Rolling-Annealing

Conventional wrought Mg alloys,such as AZ31 and ZK60 rolled plates,usually exhibit significantly low tensile yield strength in the thickness direction.This can be attributed to the high activity of{10-12}tension twinning due to the strong basal texture(<0001>//ND,normal direction).In this work,the tensile yield strength in the ND of the as-rolled(AR)AZ31 plate increased from 50 to 150 MPa(increased by 200%)via simple processing,i.e.,pre-tension and rolling-annealing(PTRA)treatment.The strong basal texture(<0001>//ND)of the AR plate was changed into a weakened fiber texture(<0001>⊥ND).The evolution of microstructures during PTRA treatment and the activated deformation modes during uniaxial tension were studied quantitatively and statistically by the means of intergranular misorientation(IM)and in-grain misorientation axes(IGMA)analysis.The results indicate that various twin variants,as well as{10-12}-{10-12}secondary twins,were activated during pre-tension and rolling,and most residual matrix was consumed by twins after annealing.The dominated deformation modes in tension changed from{10-12}tension twinning(the AR sample)to prismatic slip(the PTRA sample)in the early tensile deformation.The underlying formation mechanism of the fiber texture and corresponding strengthening mechanism were discussed.

Evaluation and adjustment of the radiometric degradation of HY-1B satellite COCTS via a stable marine site

The Chinese Ocean Color and Temperature Scanner(COCTS)on-board the Chinese second ocean color satellite,HY-1B,obtained approximately 6 years of data between 2007 and 2013 in China coastal seas and the adjacent waters.However,its radiometric performance has hardly been analyzed,which confuses its applicability in ocean remote sensing.This study tracked the long-term radiometric responsivity trend of HY-1B COCTS based on a stable marine target.Firstly,we identified a temporally stable maritime site of 12°~15°N and 116°~119°E according to the water and atmospheric optical properties using Aqua MODIS products.Then,the time-series of top-of-atmosphere(TOA)reflectance was obtained for each band of HY-1B COCTS and Aqua MODIS over this site according to the criteria of sun-target-view geometry.Finally,exponential or linear degradation models were built and used to adjust the radiometric levels of HY-1B COCTS.Results indicate that the radiometric performance exhibited continuous degradation for all bands at varying levels between 0.4%and 8.1%yr^(−1).The worst degradation occurred at 412 nm,with an annual average rate of 8.1%.The degradation at 443 nm reached 5.5%yr^(−1)following 412 nm.The radiometric performance at 490 nm,520 nm,and 565 nm was relatively stable with a drift of~3%yr^(−1).The 670 nm,750 nm,and 865 nm bands remain most stable with the degradation of~1%yr^(−1).Taking Terra MODIS as a reference,the temporal consistency of HY-1B COCTS was significantly improved for each band after radiometric adjustment.Cloud-free imageries between 2007 and 2013 showed relatively high spatial consistency.The bias of TOA reflectance was~5%in visible bands and~10%in near-infrared bands after degradation correction.These improvements confirm the application potentials of HY-1B COCTS in ocean remote sensing.

Characteristics of rural domestic sewage discharge and their driving mechanisms: evidence from the Northern Region, China

The traits of rural domestic sewage emission are unclear,negatively affecting rural domestic sewage treatment and sewage management.This study used data from the Second National Pollution Source Census Bulletin to establish a data set.The spatial distribution characteristics and main factors influencing rural sewage discharge in the Northern Region were studied using spatial autocorrelation analysis and structural equations.The findings demonstrated that(l)a significant Spearman correlation between drainage water volume(DwV),chemical oxygen demand(COD),ammonia nitrogen(NH_(3)-N),total nitrogen(TN),and total phosphorus(TP)and that the correlation coefficients between DWV and COD,NH,-N,TNand TP were 0.87**,1.0**,0.99**,0.99**,respectively;(2)rural sewage discharge showed spatial autocorrelation,and rural domestic sewage discharge in the districts and counties with an administration was significantly higher than in the surrounding areas;and(3)social development was the main driver rural domestic sewage changes(path coefficient was 0.407**),and the main factors influencing rural domestic sewage discharge were the urbanization rate,years of education,and population age structure.This study obtained the spatial variation law and clarified the main influencing factors of rural domestic sewage to provide data support and a theoretical basis for subsequent rural sewage collection and treatment.Use of the Inner Mongolia Autonomous Region in northern China as a typical case,provides a theoretical foundation for scientific decision-making on rural domestic sewage treatment at the national and regional levels and offers new perspectives for managing pollutants.

中国大陆肺炎发病率与死亡率:1985-2008年中英文文献的系统分析

目的肺炎是全球传染性疾病最主要的死因之一,但中国的肺炎疾病负担还知之甚少,因为很多数据资料都是以非英文文献的形式发表的。方法系统回顾了中国大陆关于肺炎发病率与死亡率的中文和英文文献,这些研究都是具有第一手数据的研究,1985-2008年有37篇论文符合纳入标准。结果各项研究的质量差异较大。5岁以下儿童肺炎发病率为(0.06～0.27)次/人年,肺炎死亡率为184/10万～1 223/10万人口。肺炎的发病率与死亡率随着时间稳定不变或者呈下降趋势,且农村高于城市。结论肺炎仍然是中国儿童的主要公共卫生问题之一。肺炎发病率与死亡率估计的变化差异大。继续降低发病率与死亡率需要可靠的监测数据和新的预防措施的实施,特别是在农村等高发地区。

NetEPD: A Network-Based Essential Protein Discovery Platform

Proteins drive virtually all cellular-level processes.The proteins that are critical to cell proliferation and survival are defined as essential.These essential proteins are implicated in key metabolic and regulatory networks,and are important in the context of rational drug design efforts.The computational identification of the essential proteins benefits from the proliferation of publicly available protein interaction datasets.Scientists have developed several algorithms that use these interaction datasets to predict essential proteins.However,a comprehensive web platform that facilitates the analysis and prediction of essential proteins is missing.In this study,we design,implement,and release Net EPD:a network-based essential protein discovery platform.This resource integrates data on Protein–Protein Interaction(PPI)networks,gene expression,subcellular localization,and a native set of essential proteins.It also computes a variety of node centrality measures,evaluates the predictions of essential proteins,and visualizes PPI networks.This comprehensive platform functions by implementing four activities,which include the collection of datasets,computation of centrality measures,evaluation,and visualization.The results produced by Net EPD are visualized on its website,and sent to a user-provided email,and they are available to download in a parsable format.This platform is freely available at http://bioinformatics.csu.edu.cn/netepd.

Intense ultraviolet-visible-infrared full-spectrum laser

A high-brightness ultrabroadband supercontinuum white laser is desirable for various fields of modern science.Here,we present an intense ultraviolet-visible-infrared full-spectrum femtosecond laser source(with 300–5000 nm 25 dB bandwidth)with 0.54 mJ per pulse.The laser is obtained by sending a 3.9μm,3.3 mJ mid-infrared pump pulse into a cascaded architecture of gas-filled hollow-core fiber,a bare lithium niobate crystal plate,and a specially designed chirped periodically poled lithium niobate crystal,under the synergic action of second and third order nonlinearities such as high harmonic generation and self-phase modulation.This full-spectrum femtosecond laser source can provide a revolutionary tool for optical spectroscopy and find potential applications in physics,chemistry,biology,material science,industrial processing,and environment monitoring.

Characteristics of sewer biofilms in aerobic rural small diameter gravity sewers

Small diameter gravity sewers(SDGS)are extensively used to collect rural sewage as they are low in cost and quick to construct.However,the characteristics of biofilms in rural SDGS are still not clear.In this study,biofilms characteristics of aerobic rural SDGS were investigated using simulations in a lab under different flow conditions and slopes.Results indic ated that the average thickness of aerobic rural SDGS biofilms was in the range of 350-650μm,decreasing at locations with variable flow and high slopes.Protein was the most abundant substance in extracellular polymeric substance of SDGS biofilms.The most abundant bacteria,Proteobacteria,Actinobacteria,and Bacteroidetes,and functional bacteria showed different distributions when analyzed through Illumina HiSeq sequencing of 16 S rRNA.The relative abundances of denitrifying bacteria,nitrite-oxidizing bacteria,and sulfate-reducing bacteria(SRB)were lower during variable flow than during stable flow.High slopes(15‰)decreased SRB presence,which could be used to mitigate H2 S accumulation in aerobic SDGS.Overall,this study describes the characteristics of aerobic rural SDGS biofilms and provides valuable suggestions for the optimal design of SDGS based on these characteristics.

Terawatt-Class Few-Cycle Short-Wave Infrared Vortex Laser

As a driving source for many nonlinear vortex phenomena, such as the generation of isolated attosecond optical vortices, terahertz vortices, etc., terawatt-class few-cycle short-wave infrared vortex lasers are now attracting widespread attention. However, because the vortex characteristics of optical vortices are difficult to maintain in the amplification and compression stages, the generation of high-intensity few-cycle vortex lasers is still in the exploratory stage. In this article, we report 20-Hz, 18.6-mJ, 60-fs, and 1.45-μm infrared vortex lasers with 1, 2, and 3 topological charges successfully generated in an optical parametric chirped pulse amplification system. A clean intensity node at the beam center is observed and highly stable propagation in free space is demonstrated. Moreover, this high-energy vortex pulse is spectrally broadened in multiple thin plates and temporally compressed to 10.59 fs (2.2 optical cycles) with chirped mirrors, corresponding to a peak power of 1.08 TW, while highly preserving the vortex information. We believe that the generated high-energy few-cycle vortex laser has important applications from vortex optics to strong-field physics.