This paper presents a 35.0 × 35.0 × 2.7 mm3 compact, low-profile, and lightweight wearable antenna for on-body wireless power transfer. The proposed antenna can be easily printed on a piece of flexible tattoo paper and transformed onto a PDMS substrate, making the entire antenna structure conform to the human body for achieving a better user experience. Here, a layer of frequency selective surface (FSS) is inserted in between the antenna and human tissue, which has successfully reduced the loading effects of the tissue, with 13.8 dB improvement on the antenna gain. Also, the operating frequency of the rectenna is not affected much by deformation. To maximize the RF-DC conversion efficiency, a matching loop, a matching stub, and two coupled lines are integrated with the antenna for tuning the rectenna so that a wide bandwidth (~ 24%) can be achieved without the use of any external matching networks. Measurement results show that the proposed rectenna can achieve a maximum conversion efficiency of 59.0% with an input power of 5.75 μW/cm2 and can even exceed 40% for a low input power of 1.0 μW/cm2 with a 20 kΩ resistive load, while many other reported rectennas can only achieve a high PCE at a high power density level, which is not always practical for a wearable antenna.
Q-switched Nd: YAG laser is the most effective laser for tattoo removal. Photobiomodulation (PBM) therapy is an alternative method applied to accelerate the wound healing. This paper investigated the effects of PBM therapy using 808 nm diode laser on tattooed skin after laser tattoo removal. Forty-five rats were selected and tattooed with black ink on their dorsal, and then distributed into three groups. G0 was received non-laser irradiation. G1 was treated by laser tattoo removal using 1064 nm with energy density of 3.4 J/cm2 without PBM therapy, while G2 was treated daily with PBM therapy using 808 nm diode laser of 5 J/cm2 after a single session of laser tattoo removal. The effects of tattoo removal and healing progress of the wound were analyzed using histological studies. Findings showed 808 nm laser promotes the healing process through enhancing epithelialization and collagen deposition. Moreover, PBM therapy stimulated immune cells to improve phagocytosis process for removing the tattoo ink fragments effectively. The PBM therapy treated group was capable of improving the healing process and increasing the quality of skin following the laser tattoo removal. It was also found that stimulation of cellular function by PBM therapy increased tattoo clearance efficiency.
The aetiology of the keloid scar has not been completely elucidated. Numerous hypotheses have been proposed in the past to explain the unusual characteristics of the keloid scar. While we do know that there is excessive and ongoing collagen-deposition, the exact triggering stimulus is a subject of conjecture. We present some of our photographic records of keloids and electron microscopic findings of keloid edges and reiterate the sebum hypothesis. We also attempt to explain the features of keloids in the light of the present knowledge of immunology and cell biology.
257 cases of acute hepatitis B were reported between January 1977 and June 1979. This constituted about one-third of all reported acute viral hepatitis cases in Singapore. The mean annual morbidity and mortality rates per 100,000 was 4.4 and 0.12 respectively. The case-fatality rate was 2.7%. The age-specific morbidity rates were high in the 15-24 and 25-34 years age groups, while the ethnic specific morbidity rate was highest in Indians. The male to female ratio was 4.6: 1. Cases were concentrated in urban and suburban areas with high population density. Three outbreaks, one traced to contaminated needles and syringes, one to contaminated tattoo neeedles, and amongst close contacts, were described. Although parenteral procedures were associated with hepatitis B infection (p < 0.005), non-parenteral or inapparent parenteral mode of transmission probably contributes to a significant extent in the transmission of hepatitis B in Singapore. Studies to determine the role of perinatal transmission, and of vectors, in maintaining the endemicity of the disease, were suggested.
Hepatitis C infection is a global public health problem. This study was designed to identify the risk factors associated with hepatitis C infection among adult patients in Kedah state, Malaysia. A matched, hospital-based, case-control study was conducted at a tertiary hospital. Cases were adult (aged ≥ 18 years) patients with positive serology test results for hepatitis C virus antibody and detectable hepatitis C virus RNA from January 2015 to December 2018, and controls were age-, sex- and ethnicity-matched patients who were not infected with hepatitis C virus. Self-administered questionnaires were used to collect data on demographic characteristics and previous exposure to selected risk factors among the study participants. Associations between hepatitis C and demographic and risk factors were assessed using univariable and multivariable logistic regression analyses. A total of 255 case-control patient pairs were enrolled. The multivariable analysis indicated that having a history of blood or blood product transfusion before 1992 (adjusted odds ratio [AOR] = 6.99, 95% confidence interval [CI]: 3.73-13.81), injection drug use (AOR = 6.60, 95% CI: 3.66-12.43), imprisonment (AOR = 4.58, 95% CI: 1.62-16.40), tattooing (AOR = 3.73, 95% CI: 1.37-12.00), having more than one sexual partner (AOR = 2.06, 95% CI: 1.16-3.69), piercing (AOR = 1.71, 95% CI: 1.04-2.80), and having only secondary education (AOR = 1.92, 95% CI: 1.06-3.57) were independently associated with hepatitis C. No associations were found between health care occupation, needle-prick injury, surgical procedures, haemodialysis, acupuncture, cupping, or contact sports and hepatitis C infection. These findings demonstrate that hepatitis C risk is multifactorial. Having a history of blood or blood product transfusion before 1992, injection drug use, imprisonment, tattooing, having more than one sexual partner, piercing, and having only secondary education were associated with increased odds of hepatitis C.