Laser-assisted fabrication of gold nanoparticle-composed structures embedded in borosilicate glass

We present results on laser-assisted formation of two- and three-dimensional structures comprised of gold nanoparticles in glass. The sample material was gold-ion-doped borosilicate glass prepared by conventional melt quenching. The nanoparticle growth technique consisted of two steps – laser-induced defect formation and annealing. The first step was realized by irradiating the glass by nanosecond and femtosecond laser pulses over a wide range of fluences and number of applied pulses. The irradiation by nanosecond laser pulses (emitted by a Nd:YAG laser system) induced defect formation, expressed by brown coloration of the glass sample, only at a wavelength of 266 nm. At 355, 532 and 1064 nm, no coloration of the sample was observed. The femtosecond laser irradiation at 800 nm also induced defects, again observed as brown coloration. The absorbance spectra indicated that this coloration was related to the formation of oxygen deficiency defects. After annealing, the color of the irradiated areas changed to pink, with a corresponding well-defined peak in the absorbance spectrum. We relate this effect to the formation of gold nanoparticles with optical properties defined by plasmon excitation. Their presence was confirmed by high-resolution TEM analysis. No nanoparticle formation was observed in the samples irradiated by nanosecond pulses at 355, 532 and 1064 nm. The optical properties of the irradiated areas were found to depend on the laser processing parameters; these properties were studied based on Mie theory, which was also used to correlate the experimental optical spectra and the characteristics of the nanoparticles formed. We also discuss the influence of the processing conditions on the characteristics of the particles formed and the mechanism of their formation and demonstrate the fabrication of structures composed of nanoparticles inside the glass sample. This technique can be used for the preparation of 3D nanoparticle systems embedded in transparent materials with potential applications in the design of new optical components, such as metamaterials and in plasmonics

Glycaemic control among Bulgarian children and adolescents with type 1 diabetes – an impact of the social status and the educational level of the parents

Achievement of optimal glycaemic control in children and adolescents with type 1 diabetes depends on the knowledge of the patients and their parents about the control of the disease and the family support. The aim of this study was to investigate the importance of the social standard of the families determined by the employment of the parents and their educational qualification on the control of diabetes. Two consecutive national multi-centre cross-sectional studies of patients with type 1 diabetes, aged 0–19 years, for HbA1c were conducted in 2012 and in 2014. The first study included 829 patients (422 boys, 407 girls), and the second - 498 patients; 281 patients participated in both studies. The patients whose parents are with primary education showed the highest level of HbA1c in both studies: 9.73% ± 2.38% and 9.27% ± 1.54% in the first, and the second study, respectively. The patients whose parents have university education achieved the best control: HbA1c is 8.45% ± 1.76% and 7.84% ± 1.24%, respectively. The cohorts of diabetic patients whose parents have secondary (p = 0.035) and university education (p < 0.001) showed significant reduction of HbA1c in the second study compared to the first one. The patients in families with unemployed parents or families in which only the mother is employed showed the highest levels of HbA1c. Our results underline the importance of the educational qualification and the social standard of the family for the proper control of this chronic disease

Glycemic control in type 1 diabetes mellitus among Bulgarian children and adolescents: the results from the first and the second national examination of HbA1c

The standardized hemoglobin A1c (HbA1c) test is an essential tool to evaluate the glycaemic control and the diabetes care. The aim of our study was to evaluate and compare the actual HbA1c level in a cohort of Bulgarian patients with type 1 diabetes aged 0–19 years in two consecutive national studies, in 2012 and 2014. We used a standardized method for HbA1c high performance liquid chromatography (HPLC). Тhe survey was conducted in 11 paediatric endocrinology practices in Bulgaria. Overall 829 patients with type 1 diabetes participated in the first study, 422 boys and 407 girls, aged 11.9 ± 4.2 years. The second study included 498 patients: 261 boys and 237 girls, aged 11.6 ± 4.1 years. The mean HbA1c level for the patients studied in 2014 (8.42 ± 1.69%) was significantly lower compared to that in the patients studied in 2012 (8.93 ± 1.98%, p < 0.001). Significantly more patients in the second study (36%) showed optimal control with HbA1c < 7.5% (p < 0.05) compared to those from the first one (24.9%). Teenagers in both studies had higher HbA1c levels compared to the other age groups: 9.19 ± 2.11% in 2012 and 8.8 ± 1.87% in 2014. We found significant differences in the HbA1c levels between the different centres in Bulgaria (from 7.92% to 9.95% in 2012 and from 7.42% to 9.13% in 2014). All age groups, except the teenagers showed improvement in the glycemic control in the second study as a result of continuous and structured education of the patients and their families