Howard L. Gerber

2.45 GHz radiofrequency fields alter gene expression in cultured human cells

The biological effect of radiofrequency (RF) fields remains controversial. We address this issue by examining whether RF fields can cause changes in gene expression. We used the pulsed RF fields at a frequency of 2.45 GHz that is commonly used in telecommunication to expose cultured human HL‐60 cells. We used the serial analysis of gene expression (SAGE) method to measure the RF effect on gene expression at the genome level. We observed that 221 genes altered their expression after a 2‐h exposure. The number of affected genes increased to 759 after a 6‐h exposure. Functional classification of the affected genes reveals that apoptosis‐related genes were among the upregulated ones and the cell cycle genes among the downregulated ones. We observed no significant increase in the expression of heat shock genes. These results indicate that the RF fields at 2.45 GHz can alter gene expression in cultured human cells through non‐thermal mechanism.

Determining a Pulse Coupling to Subcellular Components With a Frequency-Domain Transfer Function

This paper describes the theoretical analysis of an external rectangular time-varying electric field pulse to subcellular components in a two-shell model using published parameters. The methods use a linear analysis that provides a fourth-order solution in the frequency domain. The fourth-order model provides increased accuracy over a lower order model to calculate responses to submicrosecond pulses and susceptibility to parameter variations. The time response of a pulsed 50-ns extracellular electrical field to a nucleoplasm provides a means of comparing cell parameter estimates

Basis for the electromagnetic throttling of steel

An alternative to present methods of flow control for the continuous casting of steel is electromagnetic throttling. Here, the theory and experimental data of this casting process are presented by the author.

Analytical and Experimental Dosimetry of a Cell Culture in T-25 Flask Housed in a Thermally Controlled Waveguide

This paper describes the dosimetry of a 2.45-GHz thermally controlled waveguide exposure system containing a T-25 cell culture flask used for gene expression studies. The bottom surface of the flask is maintained at 37 degC while the remaining surfaces of the flask are at a lower temperature determined by air convection currents. Thermal gradients are set up in the cell culture medium that creates convection currents that affect cell position and exposure. The finite-element commercial software high-frequency structure simulator (HFSS) by Ansoft Corporation is used to analyze the three-dimensional distribution of electric field. The data from HFSS are exported to the finite element computational fluid dynamics (CFD) software FLUENT. The results from HFSS and CFD software agree with experimental data

Using Bode Plots to Access Intracellular Coupling

This paper describes the development of a simple model of a human B cell in suspension to predict the coupling frequency of a time varying external electric field to the nucleoplasm while minimizing any significant effects on the plasma membrane and nuclear envelope. The approach is based on the measured parameters for two-shelled model in the literature. The two-shelled model solves the Laplaces equation and assumes continuity of complex current and potential at each interface. The model is first solved using the symbolic feature in MATLAB. Using the complex current continuity boundary condition, we determine a simplified series equivalent circuit that is applicable to a specific frequency range, where most of the absorbed power in the cell occurs in the nucleoplasm. A smaller portion of the absorbed power occurs in the cytoplasm. The modeling also provides predictions of the operating frequency range for maximally selective energy targeting at the nucleoplasm.

Twin-roll casting with an electromagnetic edge dam

Twin-roll casting is an old process that was first proposed by Bessemer. Over the years one of the main problems preventing its development has been edge containment of the liquid metal pool between the rolls. Ceramic dams pressed up against the rolls have been used with some success. However, ceramic dams have the problems of requiring a super heat to prevent solidification, ceramic wearing, high cost of ceramic replacement, and finning. The electromagnetic edge dam, with an alternating horizontal magnetic field, alleviates all these problems. However, the electromagnetic edge dam, operating at relatively high frequency, has its own problems that now appear solvable with careful design of the caster and the dam. It is the purpose of this paper to present some of the solutions that have been garnered from experiments with steel and to recommend operating parameters that would be successful.

Electromagnetic processing of liquid steel

The use of electromagnetic processing of liquid steel at Inland Steel is in various stages ranging from commercial usage, with suggestions to vendors for improvements, to new application research. The status of commercially available electromagnetic stirring and electromagnetic braking are discussed. Application research of electromagnetic containment, and electromagnetic throttling are also discussed. The basic theory for electromagnetic processing of liquid steel is presented.

Heat Transfer Analysis of Human Cell Culture Under RF Exposure

A 2.45 GHz radio frequency (RF) exposure system was designed and used to study the RF effects on the genome-wide gene expression in cultured human cells. In this system, a T-25 culture flask, which contains 10 × 106 cells in a 10ml medium, is placed in a WR 340 waveguide. The waveguide serves as an environmental chamber. The source is a pulsed magnetron for obtaining a high electric field with the specific absorption rate (SAR) at approximately 10 W/kg. In order to ensure the non-thermal effect, the system was designed to maintain a temperature of 37°C. In this research, the heat transfer analysis of the system was conducted using the computational fluid dynamic (CFD) software FLUENT® coupled with the finite element software, High Frequency Structural Simulation (HFSS) by Ansoft. The electric field was first analyzed by using HFSS to calculate the SAR distribution as a heat source input for CFD calculations. The fluid flow and temperature distributions within the flask were then analyzed using FLUENT®. The results were validated experimentally by measuring the temperatures with fluoroptic thermometer probes as well as by examining the level of heat shock gene expression. These results provide useful information for a better understanding and controlling of the operating conditions of the system.Copyright

Blast furnace burden detector

A system for measuring the difference between coke and pellet layers in a blast furnace is described. The measurement is based on a high frequency magnetic proximity principle where coke, a conductor, causes a change in apparent coil resistance. Theoretical and experimental results are presented. The application of the system to No.5 Blast Furnace at Inland Steel (USA) is also presented.

Nonlinear transmission line analysis for determining harmonics

A nonlinear method for solving the one-dimensional distribution of flux density in thin laminations of motors and transformers is presented. The model assumes a sinusoidal flux density which is applied to the transmission line method to determine flux density distribution. The nonlinear relation of H to B establishes harmonics throughout the lamination thickness. The harmonic content of the coil current can also be determined from a simplified magnetic circuit taking into account a possible air gap.