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Iron fractions in the apoplast of intact root tips of Zea mays L. seedlings affected by nitrogen form

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Chinese Science Bulletin 2002年第9期47卷 727-731页

作者： h.e.Goldbach Institute of Agrichemistry Bonn University

The effects of ammonium (Nh4+-N) and nitrate (NO3- - N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0-3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture by using short-term experiment under controlled Fe deficiency conditions (containing high hCO3- concentration in pre-culture solution). The results showed that Fe(Ⅱ) concentrations in root tip apoplast of maize were only 20-40 nmol/g FW which accounted for 7%-13% of total Fe. Most of Fe in root tips existed as Fe(Ⅲ) compounds. Imposition of the roots to Nh4+ - N or NO3- - N for 60 min led to an increase of Fe(Ⅱ) in root tip apoplast. Nh4+ - N led to an increased concentration of Fe(Ⅱ) and exchangeable Fe (Fe(Ⅱ) and Fe (Ⅲ)) in root tips, while NO3- - N increased FeCN reductase activity. The relationship between ph and Fe fractions, FeCN reductase activity was also discussed.

关键词： root apoplast iron fraction nitrogen form.

DNA barcoding of Pedicularis L.(Orobanchaceae):evaluating four universal barcode loci in a large and hemiparasitic genus

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Journal of Systematics and evolution 2011年第5期49卷 425-437页

作者： richard h.Ree Department of Botany Field Museum of Natural History

One application of DNA barcoding is species identification based on sequences of a short and standardized DNA *** plants,various DNA regions,alone or in combination,have been proposed and investigated,but consensus on a universal plant barcode remains *** this study,we tested the utility of four candidate barcoding regions(rbcL,matK,trnh-psbA,and internal transcribed spacer(ITS)) as DNA barcodes for discriminating species in a large and hemiparasitic genus Pedicularis(Orobanchaceae).Amplification and sequencing was successful using single primer pairs for rbcL,trnh-psbA,and ITS,whereas two primer pairs were required for *** of sequence divergence commonly showed a "barcoding gap",that is,a bimodal frequency distribution of pairwise distances representing genetic diversity within and between species,*** primer universality,ease of amplification and sequencing,and performance in discriminating species,we found the most effective single-region barcode for Pedicularis to be ITS,and the most effective two-region barcode to be rbcL + *** discriminated at least 78% of the 88 species and correctly identified at least 89% of the sequences in our sample,and were effective in placing unidentified samples in known species *** results suggest that DNA barcoding has the potential to aid taxonomic research in Pedicularis,a species-rich cosmopolitan clade much in need of revision,as well as ecological studies in its center of diversity,the hengduan Mountains region of China.

关键词： DNA barcode hengduan Mountains region ITS Pedicularis rbcL species identification.

In vitro corrosion-fatigue behavior of biodegradable Mg/hA composite in simulated body fluid

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Journal of Magnesium and Alloys 2021年第6期9卷 2169-2184页

作者： e.Ghazizadeh A.h.Jabbari M.Sedighi School of Mechanical engineering Iran University of Science and TechnologyNarmakTehranIran

Magnesium and its composites as biodegradable materials offer especial capabilities to be used as bio-absorbable ***,their poor corrosion and fatigue properties in the physiological environment can restrict their *** this study,corrosion-fatigue tests have been performed on the extruded magnesium and magnesium/hydroxyapatite(Mg/hA)composites in a high cycle *** produce the composites,pure magnesium was reinforced by 2.5 wt.%and 5 wt.%of hydroxyapatite submicron particles using an electromagneticmechanical stirring method and hot extrusion *** experimental density measurement exhibits that the porosity increases in the extruded samples with more hydroxyapatite *** investigate the corrosion and corrosion-fatigue behavior of the specimens,simulated body fluid(SBF)was used during in vitro *** results of the potentiodynamic polarization corrosion test show that the composite with 2.5 wt.%of hydroxyapatite(Mg/2.5 wt.%hA)and the pure magnesium specimen exhibit the highest and the lowest corrosion resistance,*** the elemental mapping analysis of the corroded samples,this behavior could be due to the formation of strong phosphorus-calcium based layers on the composite *** results obtained from the mechanical tests indicate that Mg/5 wt.%hA offered the highest tensile and compressive yield strengths,as well as the most promising high cycle fatigue *** the corrosionfatigue test,the simultaneous effects of fatigue and corrosion damages led to a similar corrosion-fatigue behavior in both *** fracture surfaces of the corrosion-fatigue samples suggest that the cracks are initiated in the corroded regions of the samples surface,which reduces the crack initiation step and subsequently decreases the fatigue *** comparison with the pure magnesium,both composites exhibit more promising corrosion and corrosion-fatigue behaviors with a significant fatigue life improvement in the ph

关键词： Magnesium Magnesium/hydroxyapatite composite Corrosion Biodegradation high cycle fatigue Corrosion-fatigue

An impact of sintering temperature and doping level on structural and spectral properties of eu-doped strontium aluminium oxide

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Journal of Rare earths 2011年第12期29卷 1105-1110页

作者： R.J.Wiglusz T.Grzyb A.Watras P.J.Deren S.lis W.Strek Institute for Low Temperature and Structure Research Polish Academy of Sciences Department of Rare earths Adam Mickiewicz University

In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.

关键词： photoluminescence SrAl2O4 spinel powders eu^3+ doping nanocrystallites sol-gel method rietveld analysis Judd-Ofelt theory rare earths

Upward Molten Flow for Optimization of Fluid Flow in Continuous Casting Tundish

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Journal of Iron and Steel Research International 2010年第11期17卷 29-33页

作者： A R Alaei h edris e Shirani Department of Materials engineering Isfahan University of Technology Department of Mechanical engineering Isfahan University of Technology

Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward thetundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was carried out with the utilization of a 1 ： 4 scale model. Numerical modelling was carried out in line with the physicai modelling to examine details of the flow pattern and rotational effect caused by the upward flow with the Commercial CFD （Computational Fluid Dynamics） package environment, FLUeNT. The two-equation κ-ε model was used to simulate the turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid （VoF） method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.

关键词： upward flow continuous casting tundish numerical model water model

Layer by layer surface engineering of poly (lactide-co-glycolide) nanoparticles:A versatile tool for nanoparticle engineering for targeted drug delivery

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Science China Chemistry 2013年第8期56卷 1029-1039页

作者： ROMeRO Gabriela MURRAY richard A. QIU Yuan SANZ David MOYA Sergio e. Biosurfaces Department CIC biomaGUNE Department of Polymer Science and engineering Zhejiang University

Recent work regarding the Layer by Layer （LbL） engineering of poly（lactide-co-glycolide） nanoparticles （PLGA NPs） is reviewed here. The LbL engineering of PLGA NPs is applied as a means of generating advanced drug delivery devices with tailored recognition, protection, cargo and release properties. LbL in combination with covalent chemistry is used to attach PeG and folic acid to control cell uptake and direct it towards cancer cells. LbL coatings composed of chitosan and alginate show low protein interactions and can be used as an alternative to Pegylation. The assembly on top of LbL coatings of lipid layers composed of variable percentages of 1,2-dioleoyl-sn-glycero-3-choline （DOPC） and 1,2-dioleoyl-sn-glycero-3-phospho- L-serine （DOPS） increases NP uptake and directs the NPs towards the endoplasmic reticulum. The antibody anti-TNF-ct is encapsulated forming a complex with alginate that is assembled LbL on top of PLGA NPs. The antibody is released in cell culture following first order kinetics. The release kinetics of encapsulated molecules inside PLGA NPs are studied when the PLGA NPs are coated via LbL with different polyelectrolytes. The intracellular release of encapsulated Doxorubicin is studied in the hepG2 cell line by means of Fluorescence Lifetime Imaging.

关键词： layer by layer PLGA NPs cell uptake antibody delivery lipid layers intracellular release

A Fractional Drift Diffusion Model for Organic Semiconductor Devices

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Computers, Materials & Continua 2021年第10期69卷 237-266页

作者： Yi Yang Robert A.Nawrocki richard M.Voyles haiyan h.Zhang School of engineering Technology Purdue UniversityWest Lafayette47906USA

Because charge carriers of many organic semiconductors(OSCs)exhibit fractional drift diffusion(Fr-DD)transport properties,the need to develop a Fr-DD model solver becomes more ***,the current research on solving the governing equations of the Fr-DD model is practically *** this paper,an iterative solver with high precision is developed to solve both the transient and steady-state Fr-DD model for organic semiconductor *** Fr-DD model is composed of two fractionalorder carriers(i.e.,electrons and holes)continuity equations coupled with Poisson’s *** treating the current density as constants within each pair of consecutive grid nodes,a linear Caputo’s fractional-order ordinary differential equation(FrODe)can be produced,and its analytic solution gives an approximation to the carrier *** convergence of the solver is guaranteed by implementing a successive over-relaxation(SOR)mechanism on each loop of Gummel’s *** on our derivations,it can be shown that the Scharfetter–Gummel discretization method is essentially a special case of our *** addition,the consistency and convergence of the two core algorithms are proved,with three numerical examples designed to demonstrate the accuracy and computational performance of this ***,we validate the Fr-DD model for a steady-state organic field effect transistor(OFeT)by fitting the simulated transconductance and output curves to the experimental data.

关键词： Fractional drift diffusion model Gummel’s iteration Caputo’s fractional-order ordinary differential equation organic field effect transistor

Secure optical communication using a quantum alarm

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Light(Science & Applications) 2020年第1期9卷 380-389页

作者： Yupeng Gong Rupesh Kumar Adrian Wonfor Shengjun Ren richard V.Penty Ian h.White Centre for Advanced Photonics and electronics University of Cambridge9 JJ Thomson AveCambridge CB30FAUK Quantum Communications hub Information CentreDepartment of PhysicsUniversity of YorkYork YO105DDUK University of Bath Claverton DownBath BA27AYUK

Optical fibre networks are advancing rapidly to meet growing traffic *** issues,including attack management,have become increasingly important for optical communication networks because of the vulnerabilities associated with tapping light from optical fibre *** layer security often requires restricting access to channels and periodic inspections of link *** this paper,we report how quantum communication techniques can be utilized to detect a physical layer *** present an efficient method for monitoring the physical layer security of a high-data-rate classical optical communication network using a modulated continuous-variable quantum *** describe the theoretical and experimental underpinnings of this monitoring system and the monitoring accuracy for different monitored *** analyse its performance for both unamplified and amplified optical *** technique represents a novel approach for applying quantum signal processing to practical optical communication networks and compares well with classical monitoring *** conclude by discussing the challenges facing its practical application,its differences with respect to existing quantum key distribution methods,and its usage in future secure optical transport network planning.

关键词： communication quantum networks

Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

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World Journal of Clinical Cases 2015年第8期3卷 705-720页

作者： Yaniel Castro-Torres Raimundo Carmona-Puerta richard e Katholi Facultad de Medicina Universidad de Ciencias Médicas Dr.Serafín Ruiz de Zárate Ruiz Cardiocentro ernesto Che Guevara Southern Illinois University School of Medicine and Prairie Cardiovascular Consultants

Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization(VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. however, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients.

关键词： electrocardiographic predictor Ventricular repolarization markers Ventricular fibrillation Sudden cardiac death QT interval Corrected QT interval QT dispersion Tpeak-Tend interval Tpeak-Tend QT ratio