A multiband SSr diode RF rectifier with an improved frequency ratio for biomedical wireless applications.

This paper described a four-band implantable RF rectifier with simplified circuit complexity. Each RF-rectifier cell is sequentially matched to the four operational frequencies to accomplish the proposed design. The proposed RF rectifier can harvest RF signals at 1.830, 2.100, and white space Wi-Fi bands between 2.38 to 2.68 GHz, respectively. At 2.100 GHz, the proposed RF harvester achieved a maximum (radio frequency direct current) RF-to-DC power conversion efficiency (PCE) of 73.00% and an output DC voltage [Formula: see text] of 1.61 V for an RF power of 2 dBm. The outdoor performance of the rectenna shows a [Formula: see text] of 0.440 V and drives a low-power bq25504-674 evaluation module (EVM) at 1.362 V. The dimension of the RF-rectifier on the FR-4 PCB board is 0.27[Formula: see text] [Formula: see text] 0.29[Formula: see text]. The RF-rectifier demonstrates the capacity to effectively utilize the frequency domain by employing multi-band operation and exhibiting a good impedance bandwidth through a sequential matching technique. Thus, by effectively controlling the rectenna's ambient performance, the proposed design holds the potential for powering a range of low-power biomedical implantable devices. (BIDs).

Extracellular superoxide dismutase activity and plasma malondialdehyde in human immunodeficiency virus subjects of kano state as surrogate markers of CD4 status.

This study looked at the profile of plasma extracellular superoxide dismutase (SOD3) activity, malondialdehyde (MDA) vis-à-vis that of CD4 counts in human immunodeficiency virus subjects in Kano State, Nigeria. The subjects for this study comprised twenty (20) non-HIV infected volunteers as control and one hundred (100) HIV infected subjects. Forty nine (49) infected patients have not been on treatment, while fifty one (51) were at various stages of treatment. There was a negative correlation between the serum malondialdehyde concentration and CD4 count (Pearson r=-0.68, p<0.01). There was also a negative correlation between serum malondialdehyde concentration and extracellular superoxide dismutase activity ((Pearson r=-0.71, p<0.01) and Vitamin A concentration (Pearson r=-0.75; p<0.01). Conversely a positive correlation was observed between the CD4 counts in HIV infected patients and activity of extracellular superoxide dismutase (Pearson r=0.86, p<0.01). Similarly there was a positive correlation between CD4 count and serum vitamin A concentration (Pearson r=0.89 p<0.01). The possibility remains for using these indicators to monitor HIV patients not eligible for therapy in resource constrained facilities of our rural areas.