The transverse ferromagnet spin-1 Ising model of alternating magnetic superlattice

Within the framework of the effective field theory with a probability distribution technique that accounts for the single-site spin correlations, we examine the critical behavior of the transverse ferromagnetic spin-1 Ising model of an alternating magnetic superlattice. The critical temperature of the alternating magnetic superlattice has been studied as a function of the interlayer and intralayer exchange interactions and the strength of the transverse field and the thickness of the finite superlattice. Received 12 January 2000 and Received in final form 14 September 2000     

Biofouling prevention with pulsed electric fields

Temporary immobilization of aquatic nuisance species through application of short electric pulses has been explored as a method to prevent biofouling in cooling water systems where untreated lake, river, or sea water is used. In laboratory experiments, electrical pulses with amplitudes on the order of kilovolts/centimeter and submicrosecond duration were found to be most effective in stunning hydrazoans, a common aquatic nuisance species. Varying pulse amplitude and repetition rate allows us to control the stunning time in a temporal range from minutes to hours. The temporary immobilization is assumed to be caused by reversible membrane breakdown. This assumption is supported by results of measurements of the energy required for stunning. Based on the data obtained in laboratory experiments, field experiments in a tidal mater environment have been performed. The flow velocity was such that the residence time of the aquatic nuisance species in the system was approximately half a minute. The results showed that the pulsed electric field method provides full protection against biofouling when pulses of 0.77 μs width and 6 kV/cm amplitude are applied to the water at the inlet of such a cooling water system. Even at amplitudes of 1 kV/cm, the protection is still in the 90% range, at an energy expenditure of 1 kWh for the treatment of 60 000 gallons of water     

Promoter Methylation of RASSF1A Gene in Egyptian Patients with Ovarian Cancer

Ovarian malignancy is diagnosed in nearly a fourth of a million women internationally every year. Methylation of RASSF1A tumor suppressor gene prompts its inactivation in diseases. In this study, the RASSF1A promoter methylation was detected by methylated-specific PCR and investigated serum RASSF1A protein level through enzyme-linked immunosorbant assay in 160 Egyptian patients with ovarian cancer and 160 healthy controls. The present work proved that there was a higher frequency of RASSF1A methylation and a decrease in its serum level in patients with ovarian cancer compared to controls as well as in the high-grade tumor patients compared to low grade ones and also in advanced ovarian tumor stage compared to early stages. Our study exhibited that RASSF1A promoter hypermethylation and its protein levels may be a reliable and sensitive tool for diagnosing and monitoring of ovarian malignancy patients.     

SEM-mapped micro-photoluminescence studies of highly luminescent micro-clusters in erbium-doped silicon-rich silicon oxide

This paper reports on the formation of unique micrometer-scale clusters in erbium-doped silicon-rich silicon oxide (ErSRSO) thin films produced by thermal evaporation. Through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), we identify these micro-clusters as structures where the film curves away from the substrate to encase erbium-rich aggregates. Even though erbium aggregation has been reported to cause quenching, we demonstrate that the micro-clusters as a whole can exhibit significantly enhanced erbium photoluminescence (PL), with emissions over 24 times brighter than the surrounding non-cluster region. Mapping micro-photoluminescence measurements onto SEM images reveals that the erbium aggregates alone do not generate the enhanced PL, but rather the thin film encasing the aggregates is the origin of the emissions. Analysis of the PL Stark splitting shows a correlation between the micro-clusters’ fine structure and the strength of their PL. Taken together, the above evidence indicates that the micro-clusters’ strong PL is produced by changes in the local environment of the Er³⁺ inside the thin film surrounding the erbium-rich aggregates.     

On a systematic approach for cracked rotating shaft study: breathing mechanism,dynamics and instability

Nonlinear Dynamics - We present a systematic approach to deal with the modelling and analysis of the cracked rotating shafts behaviour. We begin by revisiting the problem of modelling the breathing...     

Design of Copper Microfabricated Potentiometric Sensor for in-line Monitoring of Neostigmine Degradation Kinetics

The quality of pharmaceutical products is critical for human health. Drug development requires tools to assess the presence of degradation products and contaminants during the manufacturing and storage processes. Accelerated stress degradation and kinetic studies play a vital role in predicting final product stability. This work describes the design of potentiometric sensor based on copper microfabricated electrodes for in-line tracking the degradation kinetics of neostigmine. The proposed electrochemical technique provides a continuous profile for the hydrolysis of NEO under different temperatures and pH. The hydrolysis activation energy was found to be 18.88 kcal mol⁻¹ which was aligned with the reported hydrolysable ester values. Consequently, the kinetic data analysis is crucial to predict the optimum analysis and storage conditions.