Search

An investigation of fluoroindate glass and fiber co-doped with Yb 3+ /Er 3+ ions as a potential temperature sensor was assessed using the fluorescence intensity ratio (FIR) technique. Analysis of thermally coupled levels (TCLs- 2 H 11/2 and 4 S 3/2 ), non-thermally coupled levels (non-TCLs- 4 F 7/2 and 4 F 9/2 ), and their combination were examined. Additionally, the luminescent stability of the samples under constant NIR excitation using different density power at three different temperatures was carried out. The obtained values of absolute sensitivity (0.003 K -1 -glass, 0.0019 K -1 -glass fiber 2 H 11/2 → 4 S 3/2 transition) and relative sensitivity (2.05% K -1 -glass, 1.64% K -1 -glass fiber 4 F 7/2 → 4 F 9/2 transition), as well as high repeatability of the signal, indicate that this material could be used in temperature sensing applications.

The effect of BaF 2 , MgF 2 , and AlF 3 on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO] 4 and [GeO] 6 units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF 2 . The 27 Al MAS NMR spectrum of BGG glass with AlF 3 suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the 4 I 13/2 → 4 I 15/2 transition of Er 3+ ions increases in the BGG + MgF 2 glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties.

Up-conversion nanoparticles have garnered lots of attention due to their ability to transform low energy light (near-infrared) into high-energy (visible) light, enabling their potential use as remote visible light nano-transducers. However, their low efficiency restricts their full potential. To overcome this disadvantage, fluoroindate glasses (InF 3 ) doped at different molar concentrations of Yb 3+ and Er 3+ were obtained using the melting-quenching technique, reaching the highest green emission at 1.4Yb and 1.75Er (mol%), which corresponds to the 4 S 3/2 → 4 I 15/2 (540-552 nm) transition. The particles possess the amorphous nature of the glass and have a high thermostability, as corroborated by thermogravimetric assay. Furthermore, the spectral decay curve analysis showed efficient energy transfer as the rare-earth ions varied. This was corroborated with the absolute quantum yield (QY) obtained (85%) upon excitation at 385 nm with QYEr = 17% and QYYb = 68%. Additionally, InF 3 -1.4Yb-1.75Er was milled and functionalized using poly(ethylene glycol) to impart biocompatibility, which is essential for biomedical applications. Such functionalization was verified using FTIR, TG/DSC, and XRD., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This study presented an analysis of the TeO 2 /GeO 2 molar ratio in an oxide glass system. A family of melt-quenched glasses with the range of 0-35 mol% of GeO 2 has been characterized by using DSC, Raman, MIR, refractive index, PLE, PL spectra, and time-resolved spectral measurements. The increase in the content of germanium oxide caused an increase in the transition temperature but a decrease in the refractive index. The photoluminescence spectra of europium ions were examined under the excitation of 465 nm, corresponding to 7 F 0 → 5 D 2 transition. The PSB (phonon sidebands) analysis was carried out to determine the phonon energy of the glass hosts. It was reported that the red ( 5 D 0 → 7 F 2 ) to orange ( 5 D 0 → 7 F 1 ) fluorescence intensity ratio for Eu 3+ ions decreased from 4.49 (Te0Ge) to 3.33 (Te15Ge) and showed a constant increase from 4.58 (Te20Ge) to 4.88 (Te35Ge). These optical features were explained in structural studies, especially changes in the coordination of [4] Ge to [6] Ge. The most extended lifetime was reported for the Eu 3+ doped glass with the highest content of GeO 2 . This glass was successfully used for the drawing of optical fiber.

This work reports on the fabrication and analysis of near-infrared and mid-infrared luminescence spectra and their decays in fluoroindate glasses co-doped with Yb 3+ /Ho 3+ . The attention has been paid to the analysis of the Yb 3+ → Ho 3+ energy transfer processed ions in fluoroindate glasses pumped by 976 nm laser diode. The most effective sensitization for 2 μm luminescence has been obtained in glass co-doped with 0.8YbF 3 /1.6HoF 3 . Further study in the mid-infrared spectral range (2.85 μm) showed that the maximum emission intensity has been obtained in fluoroindate glass co-doped with 0.1YbF 3 /1.4HoF 3 . The obtained efficiency of Yb 3+ → Ho 3+ energy transfer was calculated to be up to 61% (0.8YbF 3 /1.6HoF 3 ), which confirms the possibility of obtaining an efficient glass or glass fiber infrared source for a MID-infrared (MID-IR) sensing application.

Glass and ceramic materials doped with rare earth (RE) ions have gained wide interest in photonics as active materials for lasers, optical amplifiers, and luminescent sensors. The emission properties of RE-doped glasses depend on their chemical composition, but they can also be tailored by modifying the surrounding active ions. Typically, this is achieved through heat treatment (including continuous-wave and pulsed lasers) after establishing the ordering mechanisms in the particular glass-RE system. Within the known systems, silicate glasses predominate, while much less work relates to materials with lower energy phonons, which allow more efficient radiation sources to be constructed for photonic applications. In the present work, the luminescent and structural properties of germanate glasses modified with phosphate oxide doped with Eu 3+ ions were investigated. Europium dopant was used as a "spectroscopic probe" in order to analyze the luminescence spectra, which characterizes the changes in the local site symmetries of Eu 3+ ions. Based on the spectroscopic results, a strong influence of P 2 O 5 content was observed on the excitation and luminescence spectra. The luminescence study of the most intense 5 D 0 → 7 F 2 (electric dipole) transition revealed that the increase in the P 2 O 5 content leads to the linewidth reduction (from 15 nm to 10 nm) and the blue shift (~2 nm) of the emission peak. According to the crystal field theory, the introduction of P 2 O 5 into the glass structure changes the splitting number of sublevels of the 5 D 0 → 7 F 1 (magnetic dipole) transition, confirming the higher polymerization of fabricated glass. The slightly different local environment of Eu 3+ centers the results in a number of sites and causes inhomogeneous broadening of spectral lines. It was found that the local asymmetry ratio estimated by the relation of ( 5 D 0 → 7 F 2 )/( 5 D 0 → 7 F 1 ) transitions also confirms greater changes in local symmetry around Eu 3+ ions. Our results indicate that modification of germanate glass by P 2 O 5 allows control of their structural properties in order to functionalize the emissions for application as luminescent light sources and sensors.

We describe an unusual case of two siblings, aged 5 years and 5 months, with an unbalanced t(10;21) translocation and concomitant non-neuropathic neuropathic bladder abnormalities, whose father was a known balanced carrier of the translocation, t(10;21). Postnatally both siblings had normal spine and neurological examination. However, ultrasound scans and micturition cystourethrograms revealed grossly distended non-neuropathic neuropathic bladder. In both siblings, the bladder abnormalities responded to clean intermittent catheterisation. On follow-up, dimercaptosuccinic acid scans for both siblings showed equal split function with no scarring.

A case of congenital obstructed Treitz's hernia presenting with bilious vomiting in a newborn baby girl has been presented. Internal herniation of contents within a peritoneal sac of the right paramesocolic hernia formed abdominal cocoon which simulated volvulus neonatorum. Plain radiographs and contrast studies were helpful in defining the nature and extent of the lesion. The patient underwent exploratory laparotomy, reduction of small bowel contents from the hernial sac forming an abdominal cocoon, Ladd's procedure to correct associated midgut malrotation with incidental appendicectomy uneventfully and recovered well.

We describe the clinical presentation, radiology and clinical management of four neonates with spontaneous urinary bladder rupture and secondary urinary ascites seen in 1984 and two recent cases seen in 2007. All neonates had normal genitourinary systems on antenatal serial ultrasound scans. The management of these cases ranged from conservative management (n=3) to surgical repair of bladder (n=1). We present a review of the current literature covering management strategies and the possible role of ischemia in the pathogenesis of neonatal bladder rupture which continues to be a clinically challenging entity to diagnose and manage.

A 5 year-old girl presented with typical features of isosexual precocity with breast and pubic hair development (Tanner stage 3) and menarche, following a few months history of hirsutism of the back and thighs. Stimulation testing revealed GnRH-independent precocious puberty, tertiary hypothyroidism, hyperprolactinemia and mild testosteronemia. The ovaries in ultrasound examination were prepubertal. Tumor markers beta-hCG and AFP were markedly elevated and a 2.5 x 1.5 cm suprasellar germ cell tumor (GCT) was visualized by MRI. Combined chemotherapy followed by radiotherapy resulted in normalization of pubertal features along with estrogen and marker levels. Our observations support the possibility of hCG-dependent precocious puberty (PP) in girls caused by suprasellar hCG-secreting tumor. We emphasize the need of diagnostic management of hCG-dependent PP not only in boys, but also in girls, especially when they present even slight features of androgenization. We hypothesize that the rarity of isosexual PP in girls with hCG-secreting suprasellar GCT results not only from the lower occurrence of these tumors in girls than in boys, but above all from a rare simultaneous concomitant incidence of both high tumor aromatase activity and hCG secreting potency.

The paper presents the clinical picture, diagnostic and therapeutic management of suprasellar arachnoid cysts that result in isosexual precocious puberty in children. The authors stress the importance of physical examinations involving routine assessment of growth and sexual development as well as neurological evaluation in early diagnosis of suprasellar arachnoid cysts and other central causes of precocious puberty. The role of early diagnosis in preventing irreversible somatic and mental changes is emphasized.

A 5-year-old girl presented typical features of isosexual precocity with breast and pubic hair development (Tanner stage 3) and menarche, following a few months history of hirsutism of the back and thighs. Stimulation testing revealed GnRH-independent precocious puberty, secondary hypothyroidism, hyperprolactinemia and mild testosteronemia. The ovaries in ultrasound examination were prepubertal. Tumor markers beta-HCG and AFP were markedly elevated and a suprasellar germ cell tumor 25x15 mm in size was visualized by MRI. Combined chemotherapy followed by radiotherapy resulted in normalization of pubertal features along with estrogen and marker levels. These data indicate a possible development of precocious puberty in girls induced by choriogonadotropin (hCG) released by a supracellar germ cell tumor. Based on our observations and the literature on the subject the authors believe that the autonomous presence of aromatase inside the tumor may be responsible for precocious puberty in girls with hCG-releasing germ cell tumors, regardless of their location. In such cases the rare character of isosexual precocious puberty in girls may result from a unique combination of high hCG-releasing activity and high aromatase activity. In girls with precocious puberty, when discrete androgenization signs develop, the authors postulate to extend the diagnostic management so that hCG-dependent precocious puberty could be ruled out.