Radio-Frequency Coils in Implantable Devices: Misalignment Analysis and Design Procedure

Radio-frequency (RF) coils are used extensively in the design of implantable devices for transdermal power and data transmission. The practical issues of coil misalignments and configurations have not been investigated, and this paper presents a detailed theoretical analysis of misalignment effects in RF coil systems, including lateral and angular misalignments. Formulas are derived for the mutual inductance and, whenever possible, simplified upper bounds and lower bounds of the coupling coefficient are provided. A design procedure is established to maximize coil coupling for a given configuration, and a companion paper [1] discusses a circuit design technique to reduce the effects of misalignment on transmission efficiency.     

Design and Synthesis of Xanthone Analogues Conjugated with Aza-aromatic Substituents as Promising G-Quadruplex Stabilizing Ligands and their Selective Cancer Cell Cytotoxic Action

We have examined the stabilization of higher-order noncanonical G-quadruplex (G4) DNA structures formed by the G-rich sequences in the promoter region of oncogenes such as c-MYC, c-KIT, VEGF and BCl2 by newly synthesized, novel nitrogen-containing aromatics conjugated to xanthone moiety. Compounds with N-heterocyclic substituents such as pyridine (XNiso), benzimidazole (XBIm), quinoxaline (XQX) and fluorophore dansyl (XDan) showed greater effectiveness in stabilizing the G4 DNA as well as selective cytotoxicity for cancer cells (mainly A549) over normal cells both in terms of UV-Vis spectral titrations and cytotoxicity assay. Both fluorescence spectral titrimetric measurements and circular dichroism (CD) melting experiments further substantiated the G4 stabilization phenomenon by these small-molecular ligands. In addition, these compounds could induce the formation of parallel G4 structures in the absence of any added salt condition in Tris ⋅ HCl buffer at 25 °C. In a polymerase stop assay, the formation of stable G4 structures in the promoter of oncogenes and halting of DNA synthesis in the presence of the above-mentioned compounds was demonstrated by using oncogene promoter as the DNA synthesis template. Apoptosis-mediated cell death of the cancer cells was proved by Annexin V-PI dual staining assay and cell-cycle arrest occurred in the S phase of the cell cycles. The plausible mode of binding involves the stacking of the xanthone core on the G4 DNA plane with the possibility of interaction with the 5’-overhang as indicated by molecular dynamics simulation studies.     

Influence of crystal morphology of 1H-1,2,4-triazole on anhydrous state proton conductivity of sulfonated bisphenol A polyetherimide based polyelectrolytes

In this study, new anhydrous proton conducting polyelectrolytes were prepared based on sulfonated bisphenol A polyetherimide (SPEI) and 1H-1,2,4-triazole (Taz) as a solid state proton solvent. The effect of degree of sulfonation and triazole concentration on size, shape and dispersibility (crystal morphology) of triazole crystals in sulfonated polyetherimide were examined and correlated with proton conduction. At a constant triazole weight percent, increased sulfonation level caused enhanced nucleation density, reduction of crystallite size and their uniform distribution throughout SPEI matrix. The decrease in size was responsible for the depression of triazole melting temperature. Proton conduction through structure diffusion occurred effectively within the smaller size crystals due to the improved molecular mobility.     

Sensitivity analysis of experimentally determined grounding gridimpulse characteristics

The paper presents an experimental determination of the grounding grid impulse characteristics procedure. The measuring circuit configuration and characteristics of the applied equipment are given. Some of the numerous experimental results for three grounding grid configurations are presented. The paper provides the analysis of the results obtained for various impulse current shapes, magnitudes and discharge points. The results shown are related to the cases without soil ionization around the grid elements     

Effect of Cooling Rate on Microstructure and Mechanical Properties of Eutectoid Steel Under Cyclic Heat Treatment

A systematic study has been carried out to ascertain the effect of cooling rate on structure and mechanical properties of eutectoid steel subjected to a novel incomplete austenitization-based cyclic heat treatment process up to 4 cycles. Each cycle consists of a short-duration holding (6 min) at 775 °C (above A₁) followed by cooling at different rates (furnace cooling, forced air cooling and ice-brine quenching). Microstructure and properties are found to be strongly dependent on cooling rate. In pearlitic transformation regime, lamellar disintegration completes in 61 h and 48 min for cyclic furnace cooling. This leads to a spheroidized structure possessing a lower hardness and strength than that obtained in as-received annealed condition. On contrary, lamellar disintegration does not occur for cyclic forced air cooling with high air flow rate (78 m³ h^?1). Rather, a novel microstructure consisting of submicroscopic cementite particles in a ‘interweaved pearlite’ matrix is developed after 4 cycles. This provides an enhancement in hardness (395 HV), yield strength (473 MPa) and UTS (830 MPa) along with retention of a reasonable ductility (%Elongation = 19) as compared to as-received annealed condition (hardness = 222 HV, YS = 358 MPa, UTS = 740 MPa, %Elongation = 21).     

Intrafamilial clustering and 4-year follow-up of asymptomatic human T-cell leukaemia virus type I (HTLV-I) infection in Benin (West Africa)

Most primary sensory neurones depend on neurotrophins for survival. Mutant mice in which TrkA, the high-affinity receptor for nerve growth factor (NGF), has been inactivated lack nociceptive neurones in sensory ganglia and do not respond to noxious stimuli. The cornea of the eye is innervated by trigeminal neurones that are activated by noxious mechanical, thermal and chemical stimuli. In the human cornea, these stimuli evoke only sensations of pain. We have analysed the innervation pattern and the response to noxious stimulation of the cornea of trkA (-/-) mutant mice. Corneal nerves were stained with the gold chloride impregnation method. Corneal sensitivity to noxious stimuli was assessed by counting blinking movements evoked by von Frey hairs, topical application of saline at different temperatures and application of acetic acid and capsaicin at different concentrations. In the cornea of trkA (-/-) mutant animals, we observed a drastic reduction in the number of nerve trunks and branches in the corneal stroma. Furthermore, quantitative analysis of the number of thin nerve terminals revealed a marked decrease in the corneal epithelium of trkA (-/-) mice when compared to those present in wild type and trkA (+/-) animals. The blinking response of trkA (-/-) mice to mechanical, thermal and chemical noxious stimuli was also significantly reduced. These results indicate that the population of corneal sensory neurones is markedly depleted in trkA (-/-) mutant mice. However, a small portion of corneal sensory neurones survive in these mice suggesting that they may be NGF independent. On the basis of our results, we propose that these surviving cells are polymodal nociceptive neurones, sensitive to mechanical stimulation, noxious heat and acid.