Coarsening Dynamics of Nanoscale Ti-Silicide Islands on Si Surfaces

양우철,Matt Zeman,네마니치 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3

The late-stage coarsening dynamics of nanoscale Ti-silicide (TiSi$_2$) islands on Si surfaces is explored in ultra high vacuum (UHV) by using ultraviolet photoelectron emission microscopy (UV-PEEM). The UV-PEEM is employed for real-time, {\it in-situ} monitoring of the nanostructure dynamics and evolution at high temperatures. Continuous annealing at $\sim$1150 $^\circ$C leads to an increase in the size of the initially nucleated silicide islands and to a reduction in the number density. By monitoring the relative position and the size of individual islands, we find that islands grow through Ostwald ripening and attractive migration and coalescence (AMC). The AMC is a new coarsening process where nearby islands are observed to migrate directly towards each other and subsequently coalesce. This process has been attributed to a growth-decay flow of the island edges driven by a non-uniform chemical potential around the islands. The non-uniform chemical potential results from a varying adatom surface concentration induced by local variations in size, number, and location of the neighboring islands. Significant shape distortions of the coarsening islands, migration of each island towards the center of mass of a group of islands, and screening of attractive migration of islands with a continuous Ti flux support our suggested model for the AMC mechanism. The mass exchange between the coarsening TiSi$_2$ islands in the AMC process is explained in terms of a Ti adatom surface-diffusion-limited process.

Layer-wise numerical model for laminated glass plates with viscoelastic interlayer

Zemanova, Alena,Zeman, Jan,Janda, Tomas,Sejnoha, Michal Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

In this paper, a multi-layered finite element model for laminated glass plates is introduced. A layer-wise theory is applied to the analysis of laminated glass due to the combination of stiff and soft layers; the independent layers are connected via Lagrange multipliers. The von $K{\acute{a}}rm{\acute{a}}n$ large deflection plate theory and the constant Poisson ratio for constitutive equations are assumed to capture the possible effects of geometric nonlinearity and the time/temperature-dependent response of the plastic foil. The linear viscoelastic behavior of a polymer foil is included by the generalized Maxwell model. The proposed layer-wise model was implemented into the MATLAB code and verified against detailed three-dimensional models in ADINA solver using different hexahedral finite elements. The effects of temperature, load duration, and creep/relaxation are demonstrated by examples.

Mesoscopic study on historic masonry

Sejnoha, J.,Sejnoha, M.,Zeman, J.,Sykora, J.,Vorel, J. Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.1

This paper presents a comprehensive approach to the evaluation of macroscopic material parameters for natural stone and quarry masonry. To that end, a reliable non-linear material model on a meso-scale is developed to cover the random arrangement of stone blocks and quasi-brittle behaviour of both basic components, as well as the impaired cohesion and tensile strength on the interface between the blocks and mortar joints. The paper thus interrelates the following three problems: (i) definition of a suitable periodic unit cell (PUC) representing a particular masonry structure; (ii) derivation of material parameters of individual constituents either experimentally or running a mixed numerical-experimental problem; (iii) assessment of the macroscopic material parameters including the tensile and compressive strengths and fracture energy.

Layer-wise numerical model for laminated glass plates with viscoelastic interlayer

Alena Zemanová,Jan Zeman,Tomáš Janda,Michal Šejnoha 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

In this paper, a multi-layered finite element model for laminated glass plates is introduced. A layer-wise theory is applied to the analysis of laminated glass due to the combination of stiff and soft layers; the independent layers are connected via Lagrange multipliers. The von Kármán large deflection plate theory and the constant Poisson ratio for constitutive equations are assumed to capture the possible effects of geometric nonlinearity and the time/temperature-dependent response of the plastic foil. The linear viscoelastic behavior of a polymer foil is included by the generalized Maxwell model. The proposed layer-wise model was implemented into the MATLAB code and verified against detailed three-dimensional models in ADINA solver using different hexahedral finite elements. The effects of temperature, load duration, and creep/relaxation are demonstrated by examples.

Mesoscopic study on historic masonry

J. Šejnoha,J. Zeman,J. Sýkora,J. Vorel 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.1

This paper presents a comprehensive approach to the evaluation of macroscopic material parameters for natural stone and quarry masonry. To that end, a reliable non-linear material model on a meso-scale is developed to cover the random arrangement of stone blocks and quasi-brittle behaviour of both basic components, as well as the impaired cohesion and tensile strength on the interface between the blocks and mortar joints. The paper thus interrelates the following three problems: (i) definition of a suitable periodic unit cell (PUC) representing a particular masonry structure; (ii) derivation of material parameters of individual constituents either experimentally or running a mixed numerical-experimental problem; (iii) assessment of the macroscopic material parameters including the tensile and compressive strengths and fracture energy

Phytoremediation of Selected Explosives in a Model System of Plant Tissue Cultures

Vanek, Tomas,Nepovim, Ales,Zeman, Svatopluk The Korean Society of Plant Biotechnology 2000 식물생명공학회지 Vol.27 No.5

The phytoremediation of trinitrotoluene, nitroglycerine, pentaerytritoltetranitrate in plant tissue cultures of Solanum aviculare, Rheum palmatum and Populus simonii were studied. All above mentioned explosives were degradated to to less toxic products and finally mineralized or bound to the cell wall.

Comparison of System Architecture and Converter Topology for a Solar Powered Electric Vehicle Charging Station

G.R.Chandra Mouli,P.Bauer,M. Zeman 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Electric vehicles (EV) can be charged in a sustainable way by charging them from photovoltaic (PV) panels. Workplace charging of EV from PV results in use of the solar potential of office buildings and the long parking time at workplace paves way for implementation of vehicleto- grid (V2G) technology. In this paper, different possible system architecture for an EV-PV charger are investigated and compared. A review of power converters that integrate EV and PV is made and the systems are compared based on system architecture, converter topology, isolation and bidirectional power capability for V2G operation. Based on the study, two optimal designs for the EV-PV charger are proposed that uses a multi-port converter. Different methods to implement modularity in the converter design for charging multiple EVs from a single EV-PV charger are presented.

Topical photodynamic therapy with porphyrin precursors.assessment of treatment-associated pain in a retrospective study

Steinbauer, Julia Maria,Schreml, Stephan,Babilas, Philipp,Zeman, Florian,Karrer, Sigrid,Landthaler, Michael,Szeimies, Rolf-Markus Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.8

Photodynamic therapy (PDT) with aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) is an approved modality for the non-invasive treatment of actinic keratoses (AK) and basal cell carcinoma (BCC) offering excellent cosmetic outcome. However, pain during and after illumination is the most frequent and limiting side effect. The aim of this study was to precisely assess how reported pain during PDT is influenced by sex, age, treatment site, disease (AK/BCC) as well as the photosensitizer used. 467 lesions consisting of AK (primary treatments: n = 158; follow-up: n = 47) or BCC (primary treatments: n = 138; follow-up: 124) were treated by ALA- or MAL-PDT using metal halide lamps (580-750 nm). Pain was assessed during illumination using a continuous visual analogue scale (VAS). Factors predictive for higher pain levels during PDT are treatment of the head, treating AK and using ALA. The observed results may improve patient management and predict which level of pain to expect, and what kind of pain relief to prepare.

Randomized Crossover-Controlled Evaluation of Simultaneous Bilateral Transcutaneous Electrostimulation of the Posterior Tibial Nerve During Urodynamic Studies in Patients With Lower Urinary Tract Symptoms

Florian Girtner,Hans-Martin Fritsche,Florian Zeman,Toni Huber,Maximilian Haider,Christoph Pickl,Maximilian Burger,Roman Mayr 대한배뇨장애요실금학회 2021 International Neurourology Journal Vol.25 No.4

Purpose: Transcutaneous tibial nerve stimulation (TTNS) has proven to be a valuable treatment option for various lower urinary tract conditions, such as overactive bladder syndrome and neurogenic detrusor overactivity. The aim of this study was to investigate acute changes in urodynamic parameters due to bilateral TTNS. Methods: Fifty-one patients (18–87 years; 61% female) with various lower urinary tract symptoms were enrolled in this study. They were single-blinded and randomly assigned to receive simultaneous bilateral TTNS either during their first urodynamic examination, followed by a second round using a placebo stimulation technique, or vice versa. Results: For subjects without signs of anatomical pathologies, the filling volume at the first desire to void (FDV) increased significantly by 54 mL (interquartile range [IQR], 26–81 mL; P<0.01) under the influence of TTNS compared to placebo. The maximum cystometric capacity increased by 41 mL (IQR, 10–65 mL; P=0.02). The median micturition volume of patients with pathological postvoid residual volumes (>100 mL) increased by 76 mL compared to patients without urinary retention (IQR, 6–166 mL; P=0.03). Conclusions: Compared to placebo, simultaneous bilateral TTNS showed significant improvements in bladder functioning, such as delayed FDV, increased maximum cystometric capacity, and reduced urinary retention. Patients with signs of anatomical pathologies did not seem to benefit from TTNS. Further studies need to be conducted to compare the effectiveness of bilateral versus unilateral TTNS.

Preparation and properties of co-mixed crystals of 1,3-di- and 1,3,5-triamino- 2,4,6-trinitrobenzenes with attractive cyclic nitramines

Veerabhadragouda B. Patil,Petr Belina,Waldemar A. Trzcinski,Svatopluk Zeman 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

Co-agglomeration was used to prepare co-mixed crystals of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)with RDX, b-HMX, BCHMX and e-CL-20. The molecular rearrangements in mixed crystals were verifiedusing Raman, FTIR, and PXRD techniques. The significant stretching vibrations indicated that the resultantco-agglomerates (CACs) are co-crystals (CCs), where HMX appears in its d-modification and CL-20in its b-modification. Logical relationships, described already for the 1,3-diamino-2,4,6-trinitrobenzene(DATB) CACs, between some FTIR and Raman vibrational modes and parameters of their initiation anddetonation, after extending with the data for the TATB analogues, produced greater predictability. Thedensities of TATB CACs are higher than those of the pure nitramines (including b-CL-20). An evaluationof the dependence of the impact sensitivity on the performance or energy content in the DATB andTATB CACs is consistent with the Licht’s rule with some exceptions for DATB and an unambiguous relationshipfor the use of the heat of combustion as a representative of performance for TATB. This sensitivityis quite strongly reduced in the TATB CACs compared to their DATB analogues. The detonationenergies of the DATB and TATB CACs are higher than would be expected from the percentage of coformersin them. Among the CACs studied, the most interesting appears to be HMX/TATB, which has adensity slightly greater than pure HMX, with only slightly reduced detonation parameters, while itsimpact resistance is extremely high.