Time-domain approach to microwave circuit modeling: A view of general relations between TLM and FDTD (Invited article)

The author's research on the time-domain methods for electromagnetic simulation is reported with focus on the expanded-node FDTD and TLM approaches. The theorem of formal equivalence of FDTD and TLM together with its fundamental consequences (published recently or yet unpublished) is summarized. As an example of application of the theorem, a new family of nonequidistant TLM algorithms with controlled stability margin is originally derived by transformation from FDTD. Several meshing techniques for the modeling of irregular geometries are compared, and the locally modified grids based on local integral approximations are shown to provide optimum accuracy to computer resources ratio for practical microwave problems. © 1996 John Wiley & Sons, Inc.     

Q-switched giant pulsed erbium-doped all-fiber laser withV2ZnC MAX phase saturable absorber

MXenes, drawn from MAX phases, are special two-dimensional substances with numerous advantages in nonlinear optics, specifically in giant and ultrashort pulsed-laser applications. Ti3C2Tx and Ti2CTx nanosheets however rapidly deteriorate under ambient conditions, limiting their applications. This paper demonstrates how excellent modulation depth of one of the MAX phase compounds vanadium zinc carbide (V2ZnC) makes it a brilliant saturable absorber (SA) in passively Q-switched all-fiber pulsed lasers, integrated such that a 16.73-µm V2ZnC-polyvinyl alcohol (PVA) thin film acts as SA in the laser. Saturable and non-saturable absorptions were found to be 13.2% and 10.47%, while saturation optical intensity and modulation depth were 6.25 kW/cm2 and 12.43%, respectively, illustrating the optical nonlinearity. The superiority of MAX-PVA, fabricated in four distinct ratios, was demonstrated by the fact that it self-starts a giant pulsed laser at pump power as low as 22.5 mW and firmly accomplished 120.6 kHz repetition rate with a pulse width of 2.08 µs. It is a fine SA for the use of pulsed-laser production using all-fiber laser due to fabrication simplicity and great optical, thermophysical, and mechanical qualities.     

Recombination and Pol ζ Rescue Defective DNA Replication upon Impaired CMG Helicase—Pol ε Interaction

The CMG complex (Cdc45, Mcm2–7, GINS (Psf1, 2, 3, and Sld5)) is crucial for both DNA replication initiation and fork progression. The CMG helicase interaction with the leading strand DNA polymerase epsilon (Pol ε) is essential for the preferential loading of Pol ε onto the leading strand, the stimulation of the polymerase, and the modulation of helicase activity. Here, we analyze the consequences of impaired interaction between Pol ε and GINS in Saccharomyces cerevisiae cells with the psf1-100 mutation. This significantly affects DNA replication activity measured in vitro, while in vivo, the psf1-100 mutation reduces replication fidelity by increasing slippage of Pol ε, which manifests as an elevated number of frameshifts. It also increases the occurrence of single-stranded DNA (ssDNA) gaps and the demand for homologous recombination. The psf1-100 mutant shows elevated recombination rates and synthetic lethality with rad52Δ. Additionally, we observe increased participation of DNA polymerase zeta (Pol ζ) in DNA synthesis. We conclude that the impaired interaction between GINS and Pol ε requires enhanced involvement of error-prone Pol ζ, and increased participation of recombination as a rescue mechanism for recovery of impaired replication forks.     

Modification of Pt nanoparticles with polyoxometallate monolayers: Competition between activation and blocking of reactive sites for the electrocatalytic oxygen reduction

Surfaces of bulk platinum and unsupported (Vulcan-free) Pt nanoparticles, that are modified and stabilized with such Keggin type heteropolyacids of molybdenum and tungsten as H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀, have been characterized using cyclic voltammetry, FTIR (by reflectance), as well as transmission and scanning electron microscopies. The presence of the polyoxometallate monolayer on platinum results in the partial suppression of the interfacial formation of PtOH/PtO oxides. Both molybdates and tungstates seem to interact with Pt surface via their corner oxygen atoms. The existence of spacious, largely hydrated, polyoxometallate monolayers on platinum does not block access of reactant (oxygen) to the catalytic Pt sites. The electrocatalytic properties of H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ modified Pt nanoparticles towards reduction of oxygen in acid medium have been examined and compared using rotating ring-disk voltammetry. Reactivity of Pt-free H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ with respect to reduction of hydrogen peroxide has also been considered. Our results clearly show that modification of Pt nanoparticles with PW₁₂ (but not with PMo₁₂) results in the enhancement of the electrocatalytic reduction of oxygen.     

A model-based DSS for integrating the impact of learning in project control

Earned Value Method (EVM) is a popular project control technique. In this paper, we discuss the extended version of EVM (EVM/LC) that addresses the effect of learning on the performance of project teams. These effects have so far been ignored in most EVM applications. We present a spreadsheet-based decision support tool that automates the calculations and analyses in EVM/LC. Using this tool would save the project manager from having to perform complicated calculations while still taking advantage of the relatively accurate estimates generated by EVM/LC. Consequently, this paper contributes to both research and practice in project management.     

Elimination of microcystins by water treatment processes-examples from Sulejow Reservoir, Poland

Eutrophication is a serious problem in Polish freshwaters. Mass occurrences of toxic cyanobacteria in reservoirs cause problems in the production of safe drinking water and the diversity of produced toxins complicates monitoring of freshwaters. The aim of this study was to estimate the efficiency of water treatment processes in the removal of microcystins (MCs), cyanobacterial hepatotoxins. Elimination of microcystins was studied at two waterworks, which supply drinking water to the city of Lodz from Sulejow Reservoir. The consecutive steps of pre-oxidation, coagulation, sand filtration, ozonation and chlorination used in the water treatment showed effective elimination of microcystins in water from Sulejow Reservoir in 2002 and 2003. The highest total concentration of microcystin (variants MC-RR, MC-YR, MC-LR) amounted to 6.7 microgl(-1) in raw water and was detected on the 13th of August 2002. In 2003 the water utility decided to increase the contribution of ground water in the production of drinking water. This resulted in a decrease of microcystin in water during and after the treatment process. The current management strategy of the waterworks company includes mixing of surface water and ground water, which reduces the hazards caused by toxic cyanobacterial blooms in the reservoir.     

Studies on the increase in the incidence of endometrial and ovarian in cancer in Czechoslovakia during 1960-1973

During the time period of the last 12 years the incidence of the endometrium carcinoma in the whole CSSR rised to 155,5% in the consideration of the incidence in the years 1961 to 1963. In the same time period the incidence of the ovarial carcinoma has grown up to 117,8% only, what seems to be still in the limits of average incidence shift of all female malignancies in the CSSR (117,1%). The rising incidence of endometrium carcinoma affects primarily the elderly women, but testiefies also that this malignancy is among them today much more frequent. Therefore the rising incidence cannot be explained only as a manifestation of elderly of the female population. In agreement with this reality the endometrium carcinoma is today diagnosed significantly more frequently also among the younger women (at least since 40 years of age). The totals of all endometrium carcinomas rised even more than incidence. The gynaecologists meet today 162% of such malignancies in comparison with the numbers in the years 1961-1963. It means that in the whole CSSR yearly 500 endometrium carcinomas more are diagnosed than before 12 years. The incidence of cervix carcinoma dropped during the same period significantly and the endometrium carcinoma became therefore nearly as frequent as cervical malignancy (1:1,2). Possible reasons of these frequency changes are discussed.     

Prediction of Pectin Yield and Quality by FTIR and Carbohydrate Microarray Analysis

Pectin production is complex, and final product quality assessment is generally accomplished at the end of the process using time-consuming off-line laboratory analysis. In this study, pectin was extracted from lime peel either by acid or by enzymes. Fourier transform infrared spectroscopy and carbohydrate microarray analysis were performed directly on the crude lime peel extracts during the time course of the extractions. Multivariate analysis of the data was carried out to predict final pectin yields. Fourier transform infrared spectroscopy (FTIR) was found applicable for determining the optimal extraction time for the enzymatic and acidic extraction processes, respectively. The combined results of FTIR and carbohydrate microarray analysis suggested major differences in the crude pectin extracts obtained by enzymatic and acid extraction, respectively. Enzymatically extracted pectin, thus, showed a higher degree of esterification (DE 82 %) than pectin extracted by acid (DE 67 %) and was moreover found to be more heterogeneously esterified when probed with the monoclonal antibodies JIM5, JIM7, and LM20. The data infer that enzymatic pectin extraction allows for extraction of complex, high DE pectin, and that FTIR and carbohydrate microarray analysis have potential to be developed into online process analysis tools for prediction of pectin extraction yields and pectin features from measurements on crude pectin extracts.