Resonant Grating without a Planar Waveguide Layer as a Refractive Index Sensor.

Dielectric grating-based sensors are usually based on the guided mode resonance (GMR) obtained using a thin planar waveguide layer (PWL) adjacent to a thin subwavelength grating layer. In this work, we present a detailed investigation of thick subwavelength dielectric grating structures that exhibit reflection resonances above a certain thickness without the need for the waveguide layer, showing great potential for applications in biosensing and tunable filtering. Analytic and numerical results are thoroughly discussed, as well as an experimental demonstration of the structure as a chemical sensor in the SWIR (short wave infrared) spectral range (1200-1800 nm). In comparison to the GMR structure with PWL, the thick grating structure has several unique properties: (i) It gives higher sensitivity when the spaces are filled, with the analyte peaking at certain space values due to an increase in the interaction volume between the analyte and the evanescent optical field between the grating lines; (ii) the TM (transverse magnetic) resonance, in certain cases, provides a better figure of merit; (iii) the sensitivity increases as the grating height increases; (iii) the prediction of the resonance locations based on the effective medium approximation does not give satisfactory results when the grating height is larger than a certain value, and the invalidity becomes more severe as the period increases; (iv) a sudden increase in the Q-factor of the resonance occurs at a specific height value accompanied by the high local field enhancement (~103) characteristic of a nano-antenna type pattern. Rigorous numerical simulations of the field distribution are presented to explain the different observed phenomena.

Urinary iodine concentrations of pregnant women in Ukraine.

BACKGROUND: Iodine requirements increase during pregnancy and previous studies have reported the inadequate iodine status of pregnant women in areas that have achieved iodine sufficiency in the general population. We examined the urinary iodine (UI) concentrations of pregnant women in Ukraine, where the iodine status is showing improvement among the general population. METHODS: We enrolled 148 pregnant women<16 weeks pregnant and 80 healthy women as a control group living in Zhitomir, Ukraine. UI concentration, thyroid-stimulating hormone (TSH), antithyroglobulin antibodies (TGAb), and antithyroid peroxidase antibodies (TPOAb) were measured. RESULTS: The median UI concentrations were significantly lower in pregnant women than in control women [13.0 (ND­51.0) µg/L vs. 62.0 (35.3­108.5) µg/L, p<0.001]. TSH concentrations were significantly lower in pregnant women than in control women [1.7 (1.2­2.7) IU/L vs. 2.2 (1.4­3.1) IU/L, p=0.011], but this difference disappeared when adjusted for age (2.1±0.1 IU/L vs. 2.4±0.2 IU/L, p=0.097). The frequency of TSH over 6.2 IU/L and the frequency of positive TGAb and/or TPOAb were not statistically different between groups (p=0.70 and p=0.48, respectively). The UI concentrations of 142 pregnant women (95.9%) were <150 µg/L indicating insufficient iodine intake. CONCLUSIONS: The UI concentration of pregnant women in Ukraine revealed severe iodine deficiency. Regular monitoring and appropriate nutrition education are essential because iodine deficiency can be easily prevented by adequate iodine intake. The risk of iodine deprivation during pregnancy needs to be assessed locally over time because it may occur in areas that are not globally recognized as being iodine-deficient.

Mental health status among younger generation around Chernobyl.

INTRODUCTION: In order to improve our understanding of how to approach the younger generation around Chernobyl, we screened mental health status among young adults born after the accident living in the Gomel region, Belarus. MATERIAL AND METHODS: We enrolled 697 medical students who were born after the accident. Participants were asked to answer self-administered questionnaires including the General Health Questionnaire (GHQ-12). RESULTS: GHQ-12 scores were 1.80 ±2.28 (mean ± SD) among all 697 subjects. When logistic regression analysis was performed with confounding factors, "economic situation" and "association of diseases and/or poor health condition with radiation exposure" were significantly associated with poor mental status. CONCLUSIONS: Our findings suggest that anxiety about radiation exposure among highly educated medical students in the Gomel region, although they were born after the accident, affects their poor mental health status.

Prognosis of thyroid nodules in individuals living in the Zhitomir region of Ukraine.

OBJECTIVE: After the accident at the Chernobyl Nuclear Power Plant (CNPP), the incidence of thyroid cancer increased among children. Recently, a strong relationship between solid thyroid nodules and the incidence of thyroid cancer was shown in atomic bomb survivors. To assess the prognosis of benign thyroid nodules in individuals living in the Zhitomir region of Ukraine, around the CNPP, we conducted a follow-up investigation of screening data from 1991 to 2000 in the Ukraine. PATIENTS AND METHODS: Participants of this study were 160 inhabitants with thyroid nodules (nodule group) and 160 inhabitants without thyroid nodules (normal control group) intially identified by ultrasonography from 1991 to 2000. All participants were aged 0 to 10 years old and lived in the same area at the time of the accident. We performed follow-up screening of participants and assessed thyroid nodules by fine needle aspiration biopsy. RESULTS: Among the nodule group participants, the number and size of nodules were significantly increased at the follow-up screening compared with the initial screening. No thyroid nodules were observed among the normal control group participants. The prevalence of thyroid abnormality, especially nodules that could be cancerous (malignant or suspicious by fine needle aspiration biopsy), was 7.5% in the nodule group and 0% in the normal control group (P<0.001). CONCLUSIONS: Our study indicated that a thyroid nodule in childhood is a prognostic factor associated with an increase in the number and size of nodules in individuals living in the Zhitomir region of Ukraine.

Screening for 137Cs body burden due to the Chernobyl accident in Korosten City, Zhitomir, Ukraine: 1996-2008.

During the Chernobyl Nuclear Power Plant (CNPP) accident on 26 April 1986, large amounts of radionuclides were released and spread to vast areas. Inhabitants residing around CNPP have been exposed to external and internal irradiation due to the long half-life of (137)Cs (30 years). In this study, we screened for internal whole-body (137)Cs concentration using a whole-body counter in the Zhitomir state of Ukraine. The total number of participants was 144,972 (96,149 females and 48,823 males). The median body burden of (137)Cs per body weight decreased from 1996 to 2008. In particular, after 2003, more than half of subjects had internal exposure doses below the detectable level. A weak seasonal effect was found in measurement data from 1997 to 1999, but no such effects were observed in later years. We also calculated annual dose for each year and confirmed that doses have been decreasing gradually. In particular, after 2003, the annual effective dose decreased to 0.1 mSv y(-1) for 95% of the participants. Only two persons were found to have received more than 5 mSv y(-1) since 2007. Although the health effects of (137)Cs body burden due to the Chernobyl accident remain uncertain, further screening is needed to monitor the health status and to allay the anxiety of inhabitants in the contaminated areas around CNPP.

Evaluation of (137)Cs body burden in inhabitants of Bryansk Oblast, Russian Federation, where a high incidence of thyroid cancer was observed after the accident at the Chernobyl nuclear power plant.

To determine the current risk of internal radiation exposure after the Chernobyl accident, the (137)Cs body burden of the inhabitants of Bryansk Oblast, Russian Federation was evaluated, from 1998 to 2008. The study population is composed of 84 666 people who visited Bryansk No. 2 Hospital. A whole-body counter was used for measurement of (137)Cs body burden. (137)Cs concentration was significantly higher in the late period during the study and showed seasonal variation, suggesting that inhabitants may have consumed contaminated forest products. However, people with high annual exposure doses were quite rare during all years of the study. In conclusion, although internal radiation exposure from (137)Cs continues to this day in Bryansk Oblast, the annual exposure dose is low in almost all inhabitants. Because of the long half-life of (137)Cs, the long-term follow-up is necessary to monitor the health status and relieve the anxiety of the inhabitants around Chernobyl.

Urinary iodine concentrations in urban and rural areas around Chernobyl Nuclear Power Plant.

In 2007, we screened urinary iodine (UI) concentrations in urban (Gomel city) and in rural areas (Hoiniki city) of the Gomel Region, Republic of Belarus, which was heavily contaminated by the accident at the Chernobyl Nuclear Power Plant, in order to evaluate the current state of iodine supplementation in these areas. Median levels of UI were 220.5 microg/L (151.5-358.5) microg/L in Gomel city, and 228.0 microg/L (130.0-337.5) microg/L in Hoiniki city. Urinary concentrations in Gomel city were significantly improved, as compared to our previous results in 2000 (p<0.001). There were no differences of UI concentrations between Gomel city and Hoiniki city (p = 0.39), and none of the samples showed moderate (<50 microg/L) or severe (<20 microg/L) iodine deficiency in either city. These results suggest that the state of iodine supplementation has improved in rural areas, as well as in urban areas in the Republic of Belarus, probably due to appropriate fortification of iodized salt in this region.