White- and blue-light-emitting dysprosium(III) and terbium(III)-doped gadolinium titanate phosphors.

Here we report the synthesis and structural, morphological, and photoluminescence analysis of white- and blue-light-emitting Dy3+ - and Tm3+ -doped Gd2 Ti2 O7 nanophosphors. Single-phase cubic Gd2 Ti2 O7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy3+ -doped and ~50 nm for Tm3+ -doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy3+ -doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue-light excitation. Intense blue light was obtained for Tm3+ -doped Gd2 Ti2 O7 under UV excitation suggesting that this material could be used as a blue phosphor.

Self-referenced luminescence thermometry with Sm(3+) doped TiO2 nanoparticles.

The performance of Sm(3+) doped TiO2 nanoparticles for luminescence temperature sensing was tested over a temperature range from room to 110 °C. The Sm(3+) ions were incorporated into TiO2 nanocrystals using hydrolytic sol-gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and x-ray diffraction measurements. Luminescence emission spectra of Sm(3+) doped TiO2 nanoparticles consists of two distinct spectral regions: the high energy region associated with the trap emission of the TiO2 host, and the low energy region with well-resolved emission peaks of the Sm(3+) ions. The ratio between Sm(3+) emission and TiO2 trap emission shows strong temperature dependence, and is tested for temperature sensing. The relative sensor sensitivity was found to be higher than 1% °C(-1) over given temperature range with the maximum value of 10.54% °C(-1) at 57.5 °C. Lifetime data derived from the Sm(3+) emission decay revealed that time-resolved measurements provide comparable quality of temperature sensing as corresponding ratiometric measurements, with a maximum relative sensitivity of 10.14% °C(-1) at 66.5 °C.

Temperature sensing from the emission rise times of Eu(3+) in SrY2O4.

The emission rise time of Eu(3+)-doped SrY2O4 was investigated in the temperature range of 20-200 °C for application in luminescence thermometry. After pulsed excitation, the energy transfer between the adjacent Eu(3+) ions causes a emission build-up from the (5)D0 level of Eu(3+) and a notable emission rise occurs prior to decay. The emission rise-time values linearly decrease with temperature, providing an absolute sensitivity of 0.66 µs °C(-1) and a maximal relative sensitivity of 5.53% °C(-1) at 200 °C, for samples containing 0.5 at% Eu(3+) ions. It is shown that the time after excitation at which emission reaches a maximum (time-to-max) can also be exploited for temperature sensing, since it is easily measurable and shows a linear dependence with temperature.

The effect of eradicating Helicobacter pylori infection on the course of adenomatous and hyperplastic gastric polyps.

OBJECTIVE: Histopathological and clinical data strongly suggest that Helicobacter pylori is the cause of chronic gastritis and peptic ulceration. However, little has been written about the potential causal relation of H. pylori infection to hyperplastic and adenomatous gastric polyps. We therefore carried out a prospective study to determine the effect of eradicating H. pylori infection on the course of hyperplastic and adenomatous gastric polyps. METHODS: From November 1996 to December 1997, 6700 patients who had undergone upper gastrointestinal endoscopy at the two centres in Zagreb, Croatia, were candidates for participation in the study. Hyperplastic and adenomatous polyps were diagnosed on a basis of at least three histological samples taken from the polyp. In seven patients endoscopy had to be repeated because forceps biopsy sampling either provided inadequate tissue for correct histological diagnosis, or accurate characterization of gastric polyp histology was not possible. Upon completion of all endoscopic examinations before and after treatment, biopsy samples were taken from the antrum (two) and the body of the stomach (two) so that gastritis could be graded and classified, and the presence of H. pylori sought by histology. Two other samples were taken from the antrum for a rapid urease test. Follow-up examinations were performed by using endoscopy. Control endoscopy was performed at least 4 weeks after the treatment of H. pylori infection had been completed, and then every 3-4 months. The follow-up ranged from 4 to 17 months, with a median of 14 months. The treatment of H. pylori infection consisted of a 1-week course of either omeprazole (20 mg twice daily) or pantoprazole 40 mg twice daily), and a 1-week course of amoxicillin 2g twice daily) and metronidazole (400 mg three times daily), and clarithromycin (500 mg twice daily). Eradication of H. pylori infection was assessed by repeated histology and rapid urease test. RESULTS: Twenty-one patients (nine women, 12 men; median age 52 years) with histologically proven hyperplastic gastric polyps, and seven patients (two women, five men; median age, 67 years) with adenomatous gastric polyps were included in the study. Among 21 patients with hyperplastic gastric polyps, 16 patients (76%) were positive for H. pylori infection. Only two patients (29%) with adenomatous gastric polyps were positive for the infection. Complete eradication of H. pylori was initially achieved in all patients positive for H. pylori. Total regression of the gastric polyps was observed only among the patients with hyperplastic gastric polyps in whom H. pylori had been eradicated. Complete regression of the hyperplastic gastric polyps was observed in seven of the 16 evaluable patients (44%; 95% CI, 19-68%) after H. pylori eradication. The endoscopic snare polypectomy was carried out in nine patients with hyperplastic polyps and two patients with adenomatous gastric polyps in whom regression of the polyps was not observed after H. pylori eradication, as well as in five patients with hyperplastic and four with adenomatous gastric polyps who were negative for H. pylori. Exploratory laparotomy and gastrotomy with polyps excision were carried out in one patient with multiple adenomatous gastric polyps. In only one patient who was not positive for H. pylori recurrence of hyperplastic gastric polyp was recorded during follow-up, and no re-infection with H. pylori has been detected. CONCLUSIONS: Our results suggest that the development of hyperplastic gastric polyps may be directly related to chronic active gastritis and concomitant H. pylori infection. Cure of H. pylori infection associated with hyperplastic gastric polyps resulted in complete polyp regression in more than 40% of patients. Therefore, for patients with hyperplastic gastric polyps and concurrent H. pylori infection an antibiotic treatment designed to eradicate H. pylori appears to be recommended before further therapeutic options are consi

Whipple's disease: a case study with unexpected prognosis.

Due to the systemic nature of Whipple's disease, its clinical presentation may be highly variable. The diagnosis may, therefore, be unduly delayed. Untreated, Whipple's disease is still potentially lethal. Although it traditionally presents with signs and symptoms of small intestine involvement, such as diarrhea and malabsorption, Whipple's disease can involve many other organs. Typically, the diagnosis is established by biopsy of the small intestine. The authors describe a case of Whipple's disease in order to stress the importance of bearing this polymorphic disease in mind, with special emphasis on its possible lethal outcome in spite of therapy.

Medical treatment of gastroesophageal reflux disease.

Medical therapy for reflux esophagitis is designed to provide symptom relief and esophageal healing, and to prevent complications. Life-style modifications serve as an adjunct to drug therapy. Histamine-H2-receptor antagonists and prokinetic agents promote symptom relief and esophageal healing in mild esophagitis, but are less effective in the treatment of moderate to severe esophagitis. For patients with moderate to severe esophagitis, rapid symptom relief and esophageal healing have been achieved with proton pump inhibitors. These patients usually require maintenance therapy with proton pump inhibitors.