Temperature and strain sensitivities of a groove bonded fiber Bragg grating at room and cryogenic temperatures.

Optical fiber Bragg gratings (FBGs) are well suited for applications as temperature or/and strain sensors in harsh environments, e.g., detecting thermal hot spots in high-temperature superconductor (HTS) fusion energy magnets at cryogenic temperatures and high radiation environments. To maximize the signal-to-noise ratio (SNR) of the FBGs to a hot spot, we propose to have them mounted in V-shaped grooves of HTS' copper former. To investigate the differences between different adhesives on transferring strain and heat in this configuration, five arrays of FBGs are mounted in the V-shaped grooves of a copper dog-bone using Scotch-Weld epoxy, Stycast 2850 FT, Apiezon N, and Loctite 5145 silicone. The copper is cycled through tensile forces in a modified universal tensile tester, subjected to a thermal cycle between 293 K and 77 K, and exposed to heat pulse propagations at 293 K and 80 K. The FBGs that are bonded using Stycast show the highest temperature and strain sensitivities at room and cryogenic temperatures. No major differences in the temperature and strain sensitivities have been found between Ormocer and polyimide coated FBGs. Apiezon N is found to transfer strain consistently well below 245 K, which is comparable with other bonding materials in the temperature range between 77 K and 110 K. The FBGs bonded with the four adhesives in the V-groove configurations are shown to have comparable SNRs to a temperature rise of 20 K at 80 K. This paper emphasizes the importance of maximizing the thermal strain transferred from the host material through the bonding agents to achieve high temperature sensitivity of FBGs.

Review of Wearable and Portable Sensors for Monitoring Personal Solar UV Exposure.

Sunlight is one of the main environmental resources that keeps all the organisms alive on earth. The ultraviolet (UV) radiation from the sun is essential for vitamin D synthesis in the human body, which is crucial for bone and muscle health. In addition, sun exposure also helps to reduce the risk of some cardiovascular diseases and cancers. However, excessive UV exposure can lead to adverse effects, including some eye diseases, premature aging, sunburn and skin cancers. The solar UV irradiance itself depends on many environmental factors. In fact, the UV index reported in weather forecasts is an estimation under cloudless conditions. Personal UV exposure also depends on one's outdoor activities and habits. Furthermore, the UV intake depends on the skin sensitivity. Therefore, there is a need for research into monitoring the optimal daily UV exposure for health benefits, without developing potential health risks. To facilitate the monitoring of solar UV intensity and cumulative dose, a variety of UV sensors have been developed in the past few decades and many are commercially available. Examples of sensors being marketed are: portable UV dosimeter, wearable UV radiometer, personal UV monitor, and handheld Solarmeter®. Some of the UV sensors can be worn as personal health monitors, which promote solar exposure protection. The paper provides a comprehensive review of the wearable and portable UV sensors for monitoring personal UV exposure, including a discussion of their unique advantages and limitations. Proposals are also presented for possible future research into reliable and practical UV sensors for personal UV exposure monitoring.

Effect of hair removal on solar UV transmission into skin and implications for melanoma skin cancer development.

Melanoma is the severest type of skin cancer. As distinct from many other cancer types, the incidence of melanoma has been increasing steadily over the last century. Discovering new risk factors of melanoma will not only raise public awareness but also potentially contribute to the improvement of skin cancer protection in the future. Nowadays, the tendency of shaving skin hair is becoming increasingly popular for aesthetic purposes. However, human hair serves several functions, one of which is ultraviolet (UV) protection for the skin. What is more, stem cells found in the follicles of hair could be the origin of melanoma upon exposure to ultraviolet radiation. Therefore, it is of interest to investigate the effect of shaving on solar UV transmission in the skin. To achieve that, two groups of skin models are constructed in TracePro software: one with unaltered hair and one with shaved hair. The UV transport in the models is simulated using the Monte Carlo method and the absorptions in the stem cells layer are compared. It is found that shaving will increase the UV transmission to the follicular stem cells to a certain degree. More specifically, shaving limbs will generally increase the solar UV transmission from about 5% to 20% in the UV wavelength range.

Contribution of Human Hair in Solar UV Transmission in Skin: Implications for Melanoma Development.

Melanoma is the deadliest type of skin cancer with its prevalence on the rise. Recently, the melanocyte stem cells in hair follicles have been identified as the possible origin of melanoma upon exposure to ultraviolet radiation (UVR) through skin. It is hypothesized that colourless vellus hair (predominant in childhood) can serve as an alternative pathway in transmitting these ultraviolet (UV) photons to the stem cells. To investigate this, we have used the CRAIC microspectrophotometer to investigate the optical properties of 'vellus-like' hairs and terminal hairs of different colours using UV-VIS-NIR light sources. It was found that the average attenuation coefficient of 'vellus-like' hair is significantly lower than that of terminal hair in the UVA (p < 0.0001) and UVB (p < 0.001) wavelength ranges. Next, the optical properties of hairs are applied to simulations for examining their influence on UV transmission into the skin. The results show that the presence of vellus hair would increase the solar UV transmission to the melanocyte stem cell layer significantly. The findings explain why children are particularly vulnerable to sun exposure and the positive correlation found between the incidence of melanoma in adults' bodies and the number of vellus hairs in these areas.

Stretchable and sensitive sensor based on carbon nanotubes/polymer composite with serpentine shapes via molding technique.

With the rapid development of wearable devices in recent years, stretchable strain sensors based on electrically conductive composites have attracted a great deal of attention owing to their good stretchability and piezoresistivity. However, due to the intrinsic restriction of these types of composites, the conventional stretchable strain sensors cannot do well in all aspect of sensing performance. A stretchable strain sensor based on carbon nanotubes/poly(dimethylsiloxane) composite with the serpentine shape was devised and fabricated. The sensor was readily manufactured through a molding technique. Not only can this sensor distinguish tension strain from transverse or longitudinal direction, but also exhibits good linearity of response to tensile strain. In terms of sensitivity, hysteresis and response time, the stretchable strain sensor showed significant performance. The sensing performance of this proposed stretchable sensor has been demonstrated to be good in this work and it also shows a good prospect for utilization in multifunctional wearable devices.

Simulation of UV power absorbed by follicular stem cells during sun exposure and possible implications for melanoma development.

The incidence of melanoma in children is extremely rare. However, there is convincing evidence supporting a higher risk of developing melanoma in individuals who have experienced excessive sun exposure during their childhood. A possible explanation for this phenomenon is that prior to puberty, the melanocyte stem cells in the bulge region of hair follicles are much shallower in the dermis, resulting in their increased vulnerability to sun exposure. To validate this hypothesis, a Monte Carlo simulation of light transport is applied to quantify the dose of solar UV power absorbed in the stem-cell layers at different depths in both child and adult skins. The simulated results suggest that the stem cells in vellus hair follicles would absorb over 250 times higher UV photons than those in the terminal hair follicles. Due to the thinner epidermis in child skin, the stem cells in vellus hair follicles absorb about 1.9 and 3.2 times greater ultraviolet A and ultraviolet B, respectively, than those in adult skin. These findings provide a possible explanation to why children are particularly vulnerable to sun exposure.

Review of human hair optical properties in possible relation to melanoma development.

Immigration and epidemiological studies provide evidence indicating the correlation of high ultraviolet exposure during childhood and increased risks of melanoma in later life. While the explanation of this phenomenon has not been found in the skin, a class of hair has been hypothesized to be involved in this process by transmitting sufficient ultraviolet rays along the hair shaft to possibly cause damage to the stem cells in the hair follicle, ultimately resulting in melanoma in later life. First, the anatomy of hair and its possible contribution to melanoma development, and the tissue optical properties are briefly introduced to provide the necessary background. This paper emphasizes on the review of the experimental studies of the optical properties of human hair, which include the sample preparation, measurement techniques, results, and statistical analysis. The Monte Carlo photon simulation of human hair is next outlined. Finally, current knowledge of the optical studies of hair is discussed in the light of their possible contribution to melanoma development; the necessary future work needed to support this hypothesis is suggested.

[Transcatheter closure in various types of congenital coronary artery fistula: a follow-up study].

OBJECTIVE: To evaluate the short- and medium-term efficacy, complications, and anti-coagulation therapies related to transcatheter closure (TCC) of coronary artery fistula (CAF) in children. METHODS: We conducted a retrospective review of the medical records of 12 children with CAF who underwent TCC between January 2006 and January 2014, focusing on details such as preoperative, radiographic, and postoperative follow-up data, to record closure methods for CAF, anti-coagulation therapies, postoperative complications, and results of auxiliary examinations. RESULTS: Among the 12 cases who underwent successful TCC and whose age was 1-158 months, four patients had proximal/medium-sized CAF, five had proximal/large CAF, and three had distal/medium-sized CAF. The mean period of postoperative follow-up was 3.5±2.4 years. Eleven patients took aspirin for 6 months post closure, and one took it for 18 months. Neither coronary thrombosis nor interventional complications were found. Left ventricular ejection fraction, cardiothoracic ratio, pulmonary artery pressure, and the diameters of coronary artery lesions decreased post TCC. CONCLUSIONS: TCC is feasible and safe in proximal and distal/medium-sized CAF patients. Postoperative anti-coagulation with aspirin may prevent short- and medium-term thrombosis, but treatment course and safety need to be investigated by further follow-ups.

[Research advance of brain natriuretic peptide and N-terminal brain natriuretic peptide in the diagnosis and treatment of pediatric cardiovascular diseases].

Brain natriuretic peptide (BNP) and N-terminal brain natriuretic peptide (NT-proBNP) are important biomarkers for pediatric cardiovascular diseases. Peptide levels are associated with age and gender. Current studies have shown that BNP and NT-proBNP are valuable in the diagnosis of heart failure, with a high specificity and sensitivity. They also contribute to differentiating heart failure from acute respiratory distress induced by simple pulmonary factors. In addition, BNP and NT-proBNP are useful in the evaluation of disease severity and treatment guidance in children with pulmonary hypertension, cardiomyopathy and Kawasaki disease. Current limitations include the relatively small sample size of the study, the detection method and a range of normal values that are not completely uniform.