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Journal of Forestry Research 2021年第1期32卷 363-370页

作者： lenka pavlů LubošBorůvka Ondřej Drábek Antonín Nikodem Department of Soil Science and Soil Protection Faculty of AgrobiologyFood and Natural ResourcesCzech University of Life Sciences PraguePragueCzechia

To elucidate the dynamics of aluminium(Al),an element potentially toxic and strongly aff ected by acidifi cation processes,in soils,we selected two regions that were similar in relief,soil types,and vegetation cover but diff ered markedly in their history of acid precipitation:the JizerskéMountains(anthropogenically acidifi ed)and the NovohradskéMountains(naturally acidifi ed)in the Czech *** levels of Al forms(exchangeable and organically bound)associated with diff erent environmental impacts were measured and univalent,divalent and trivalent Al species were quantifi ed using HPLC/*** and organically bound Al concentrations were higher in the anthropogenically acidifi ed *** the concentrations of the leastdangerous species,the univalent,in organic soil horizons were similar for both *** concentrations of exchangeable Al forms were correlated with Ca concentrations and with pH in the organic *** known relationship of Al with soil pH was stronger in the mineral *** of exchangeable Al forms concentrations with sulphur concentrations or even more with the sulphur calcium molar ratio were found only in the JizerskéMountains,not in the Novohradské.Generally,the obtained results support the hypothesis that mechanisms diff ered between natural and anthropogenic acidifi cation.

关键词： Soil acidifi cation Spruce forest Soil properties Aluminium forms Aluminium species

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Nuclear Science and Techniques 2019年第8期30卷 100-113页

作者： lenka Frybortova UJV Rez a.s. Faculty of Nuclear Sciences and Physical Engineering Czech Technical University in Prague

There is an obvious effort to increase the burn up of used fuel assemblies in order to improve fuel utilization.A more effective operation can be realized by extending the fuel cycles or by increasing the number of *** change is nevertheless connected with increasing the uranium enrichment even above 5% of 235U. Burnable absorbers are widely used to compensate for the positive reactivity of fresh fuel. With proper optimization, burnable absorbers decrease the reactivity excess at the beginning of the cycle, and they can help with stabilization of power distribution. This paper describes properties of several materials that can be used as burnable absorbers. The change in concentration or position of the pin with a burnable absorber in a fuel assembly was analyzed by the HELIOS transport lattice code. The multiplication factor and power peaking factor dependence on fuel burn up were used to evaluate the neutronic properties of burnable absorbers. The following four different materials are discussed in this paper: Gd2O3, IFBA, Er2O3,and *** had the greatest influence on fuel characteristics. The number of pins with a burnable absorber was limited in the VVER-440 fuel assembly to six. In the VVER-1000 fuel assembly, 36 pins with a burnable absorber can be used as the assembly is larger. The erbium depletion rate was comparable with uranium burn *** had the largest parasitic absorption after depletion.

关键词： Burnable absorber Gadolinium IFBA Erbium Dysprosium Power peaking VVER fuel HELIOS code

Potential of kynurenine metabolites in drug development against neurodegenerative diseases

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Neural Regeneration Research 2021年第2期16卷 308-309页

作者： lenka Kubicova Vladimir Chobot Division of Molecular Systems Biology Department of Ecogenomics and Systems BiologyFaculty of Life SciencesUniversity of ViennaViennaAustria

Reactive oxygen species(ROS)and kynurenines:Kynurenines represent a relatively heterogenous group of tryptophan metabolites(Figure 1 A).The amino acid tryptophan is metabolized in the humans by the kynurenine or serotonin *** a long time,the kynurenine pathway was assumed primarily to constitute the source for nicotinamide-adenine dinucleotide phosphate,one of the most utilized redox active enzyme cofactors.

关键词： Figure assumed utilized

Performance analysis of 20 nm gate-length In_(0:2)Al_(0:8)N/GaN HEMT with Cu-gate having a remarkable high I_(ON)/I_(OFF)ratio

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Journal of Semiconductors 2014年第6期35卷 26-31页

作者： A.Bhattacharjee T.R.lenka Department of Electronics and Communication Engineering National Institute of Technology Silchar

： We propose a new structure of InxAll-xN/GaN high electron mobility transistor （HEMT） with gate length of 20 nm. The threshold voltage of this HEMT is achieved as -0.472 V. In this device the InA1N barrier layer is intentionally n-doped to boost the ION/IOFF ratio. The InAlN layer acts as donor barrier layer for this HEMT which exhibits an ION = 10-4.3 A and a very low IOFF = 10-14.4 A resulting in an ION/IoFF ratio of 1010.1. We compared our obtained results with the conventional InAlN/GaN HEMT device having undoped barrier and found that the proposed device has almost l0s times better ION/IOFF ratio. Further, the mobility analysis in GaN channel of this proposed HEMT structure along with DC analysis, C-V and conductance characteristics by using small-signal analysis are also presented in this paper. Moreover, the shifts in threshold voltage by DIBL effect and gate leakage current in the proposed HEMT are also discussed. InAlN was chosen as the most preferred barrier layer as a replacement of AlGaN for its excellent thermal conductivity and very good scalability.

关键词： C-V characteristics DIBL GaN HEMT ION/IOFF mobility

A general method for assaying homo-and hetero-transglycanase activities that act on plant cell-wall polysaccharides

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Journal of Integrative Plant Biology 2015年第4期57卷 411-428页

作者： lenka Franková Stephen C.Fry The Edinburgh Cell Wall Group Institute of Molecular Plant SciencesThe University of EdinburghDaniel Rutherford BuildingThe King's Buildings

Transglycanases（endotransglycosylases） cleave a polysaccharide（donor-substrate） in mid-chain, and then transfer a portion onto another poly-or oligosaccharide（acceptor-substrate）. Such enzymes contribute to plant cellwall assembly and/or re-structuring. We sought a general method for revealing novel homo- and hetero-transglycanases, applicable to diverse polysaccharides and oligosaccharides, separating transglycanase-generated3 Hpolysaccharides from unreacted3H-oligosaccharides—the former immobilized（on filter-paper, silica-gel or glassfiber）,the latter eluted. On filter-paper, certain polysaccharides [e.g.（1!3, 1!4）-b-D-glucans] remained satisfactorily adsorbed when water-washed; others（e.g. pectins） were partially lost. Many oligosaccharides（e.g. arabinan-, galactan-, xyloglucan-based） were successfully eluted in appropriate solvents, but others（e.g. [3H]xylohexaitol, [3H]mannohexaitol[3H]cellohexaitol） remained immobile. On silica-gel, all3 Holigosaccharides left an immobile ‘ghost’ spot（contaminating any3H-polysaccharides）, which was diminished but not prevented by additives e.g. sucrose or Triton X-100. The best stratum was glassfiber（GF）, onto which the reactionmixture was dried then washed in 75% ethanol. Washing led to minimal loss or lateral migration of3H-polysaccharides if conducted by slow percolation of acidified ethanol. The effectiveness of GF-blotting was well demonstrated for Chara vulgaris transb-mannanase. In conclusion, our novel GF-blotting technique ef ficiently frees transglycanase-generated3H-polysaccharides from unreacted3H-oligosaccharides,enabling high-throughput screening of multiple postulated transglycanase activities utilising chemically diverse donorand acceptor-substrates.

关键词： Glass-fiber blotting plant cell wall polysaccharides(donor) radiolabeled oligosaccharides (acceptor) transglycanase

Influence of COM-peptides/proteins on the properties of flocs formed at different shear rates

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Journal of Environmental Sciences 2019年第6期31卷 116-127页

作者： Monika Filipenska Petra Vasatova lenka Pivokonska lenka Cermakova andrea Gonzalez-Torres Rita K.Henderson Jana Naceradska Martin Pivokonsky Institute of Hydrodynamics of the Czech Academy of Sciences Institute for Environmental Studies Faculty of Science Charles University The bioMASS Lab School of Chemical Engineering The University of New South Wales

Coagulation followed by floc separation is a key process for the removal of algal organic matter(AOM) in water treatment. Besides optimizing coagulation parameters,knowledge of the properties of AOM-flocs is essential to maximizing AOM ***, the impact of AOM on the floc properties remains unclear. This study investigated how peptides/proteins derived from the cellular organic matter(COM) of the cyanobacterium Microcystis aeruginosa influenced the size, structure, and shape of flocs formed at different shear rates(G). Flocs formed by kaolinite, COM-peptides/proteins and a mixture of the same were studied, and the effect of intermolecular interactions between floc components on floc properties was assessed. The coagulation experiments were performed in a Taylor–Couette reactor, with aluminum(Al) or ferric sulphate(Fe) utilized as coagulants. Image analysis was performed to gauge floc size and obtain data on fractal dimension. It was found that floc properties were affected by the presence of the COM-peptides/proteins and the coagulant used. COM-peptides/proteins increased floc size and porosity and widened floc size distributions. The Fe coagulant produced larger and less compact flocs than Al coagulant. Moreover, the decrease in floc size that occurred in parallel with increase in shear rate was not smooth in progress. A rapid change for the kaolinite-coagulant suspension and two rapid changes for the suspensions containing COM were observed. These were attributed to various intermolecular interactions between floc components participating in coagulation at different G. Based on the results obtained, shear rates suitable for efficient separation of flocs containing COM were suggested.

关键词： Algal organic matter Floc size Coagulation Image analysis Water treatment

Model development for analyzing 2DEG sheet charge density and threshold voltage considering interface DOS for AlInN/GaN MOSHEMT

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Journal of Semiconductors 2014年第10期35卷 26-29页

作者： Devashish Pandey T.R.lenka Department of Electronics and Communication Engineering National Institute of Technology Silchar

A model predicting the behavior of various parameters, such as 2DEG sheet charge density and thresh- old voltage, with the variation of barrier thickness and oxide thickness considering interface density of states is presented. The mathematical dependence of these parameters is derived in conjunction with the interface density of states. The dependence of sheet charge density with the barrier thickness and with the oxide thickness is plotted and an insight into the barrier scaling properties of AIInN based MOSHEMTs is presented. The threshold voltage is also plotted with respect to barrier thickness and oxide thickness, which reveals the possibility of the enhance- ment mode operation of the device at low values of the interface DOS. The results are in good agreement with the fabricated device available in the literature.

关键词： DOS AIlnN MOSHEMT 2DEG barrier scaling

Adaptive hp-FEM with Arbitrary-Level Hanging Nodes for Maxwell’s Equations

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Advances in Applied Mathematics and Mechanics 2010年第4期2卷 518-532页

作者： Pavel Solin lenka Dubcova Ivo Dolezel Department of Mathematics and Statistics University of NevadaReno89557USA Institute of Thermomechanics Academy of Sciences of the Czech RepublicNarodni 311720 Praha 1Czech Republic

Adaptive higher-order finite element methods(hp-FEM)are well known for their potential of exceptionally fast(exponential)***,most hp-FEM codes remain in an academic setting due to an extreme algorithmic complexity of hp-adaptivity *** paper aims at simplifying hpadaptivity for H(curl)-conforming approximations by presenting a novel technique of arbitrary-level hanging *** technique is described and it is demonstrated numerically that it makes adaptive hp-FEM more efficient compared to hp-FEM on regular meshes and meshes with one-level hanging nodes.

关键词： hp-FEM arbitrary-level hanging nodes irregular meshes higher-order edge elements Maxwell’s equations

Investigating the coagulation of non-proteinaceous algal organic matter: Optimizing coagulation performance and identification of removal mechanisms

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Journal of Environmental Sciences 2019年第5期31卷 25-34页

作者： Jana Naceradska Katerina Novotna lenka Cermakova Tomas Cajthaml Martin Pivokonsky Institute of Hydrodynamics of the Czech Academy of Sciences Institute of Microbiology of the Czech Academy of Sciences

The removal of algal organic matter(AOM) is a growing concern for the water treatment industry worldwide. The current study investigates coagulation of non-proteinaceous AOM(AOM after protein separation), which has been minimally explored compared with proteinaceous fractions. Jar tests with either aluminum sulphate(alum) or polyaluminium chloride(PACl) were performed at doses of 0.2–3.0 mg Al per 1 mg of dissolved organic carbon in the p H range 3.0–10.5. Additionally, non-proteinaceous matter was characterized in terms of charge, molecular weight and carbohydrate content to assess the treatability of its different fractions. Results showed that only up to 25% of non-proteinaceous AOM can be removed by coagulation under optimized conditions. The optimal coagulation p H(6.6–8.0 for alum and 7.5–9.0 for PACl) and low surface charge of the removed fraction indicated that the prevailing coagulation mechanism was adsorption of non-proteinaceous matter onto aluminum hydroxide precipitates. The lowest residual Al concentrations were achieved in very narrow p H ranges, especially in the case of PACl. High-molecular weight saccharidelike organics were amenable to coagulation compared to low-molecular weight(< 3 k Da)substances. Their high content in non-proteinaceous matter(about 67%) was the reason for its low removal. Comparison with our previous studies implies that proteinaceous and nonproteinaceous matter is coagulated under different conditions due to the employment of diverse coagulation mechanisms. The study suggests that further research should focus on the removal of low-molecular weight AOM, reluctant to coagulate, with other treatment processes to minimize its detrimental effect on water safety.

关键词： Algal organic matter Chlorella vulgaris Coagulation Flocculation Non-proteinaceous matter Water treatment

Impact of barrier thickness on gate capacitance—modeling and comparative analysis of GaN based MOSHEMTs

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Journal of Semiconductors 2015年第3期36卷 60-64页

作者： Kanjalochan Jena Raghunandan Swain T.R.lenka Department of Electronics and Communication Engineering National Institute of Technology Silchar

A mathematical model is developed predicting the behavior of gate capacitance with the nanoscale variation of barrier thickness in AlN/GaN MOSHEMT and its effect on gate capacitances of AIInN/GaN and AlGaN/GaN MOSHEMTs through TCAD simulations is compared analytically. AlN/GaN and AIInN/GaN MOSHEMTs have an advantage of a significant decrease in gate capacitance up to 108 fF/μm^2 with an increase in barrier thickness up to 10 nm as compared to conventional AlGaN/GaN MOSHEMT. This decrease in gate capacitance leads to improved RF performance and hence reduced propagation delay.

关键词： 2DEG GaN MOSHEMT quantum capacitance TCAD