A double layer FSS filter for sub-THz applications.

This work presents the simulated and measured performance of single- and double-layer frequency selective surface filters for operation at sub-THz frequencies (250 GHz center frequency). They were composed of concentric square loops with a split as a unit cell resonator on top of a low dielectric permittivity, low thickness material (RT5880). Both a single layer filter and a cascaded two layer filter with varied distances were investigated. The simulated bandwidth for the cascaded filter was 27 GHz and 16 GHz and 9 GHz bandwidth measured with a THz-TDS and microwave system.

rClca2 is associated with epidermal differentiation and is strongly downregulated by ultraviolet radiation.

BACKGROUND: Excessive skin exposure to solar radiation damages proteins and DNA, ultimately leading to skin ageing and cancers. OBJECTIVES: To identify new ultraviolet B (UVB) target genes to understand the mechanisms behind the detrimental effects of UVB. METHODS: Organotypic, stratified cultures of rat keratinocytes were exposed to UVB and analysed using a genome-wide expression array, quantitative real-time polymerase chain reaction and histology. The most downregulated gene, rClca2, was further characterized in rat keratinocytes and mouse skin models. RESULTS: A single, 30 mJ cm(-2) dose of broadband UVB proved effective in the organotypic epidermal culture. The expression of 627 genes was changed 24 h postirradiation. In silico analysis of the data indicated activation of DNA repair, metabolism, cell cycle control and amino acid metabolism, but only limited inflammation under these conditions. We selected for further investigation the most downregulated gene, rClca2, previously suggested to regulate keratinocyte differentiation and adhesion, and found that UVB caused a long-lasting downregulation in its expression. Both the rClca2 full-length isoform (expressed in the differentiating cells) and the truncated isoform (expressed in the basal layers) were reduced by UVB. Immunohistochemistry of mouse skin samples with isoform-specific antibodies showed a similar, epidermal differentiation-related pattern. In mouse specimens exposed to chronic ultraviolet radiation (UVR) the staining intensities were reduced and the differentiation-related isoform was disturbed in the hyperplastic and carcinomatous areas induced by UVR. CONCLUSIONS: The data show that rClca2 is a novel UVB target gene and suggest that it might play a role in epidermal differentiation and UV-dependent skin malignancies.

Mycotoxin production of Fusarium langsethiae and Fusarium sporotrichioides on cereal-based substrates.

The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cereal-flour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cereal-based assays but was more predominant on the carbohydrate-rich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000 µg/kg after 7 days' incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.

Deflection fatigue of cobalt-chromium, titanium, and gold alloy cast denture clasp.

The aim of this study was to determine the fatigue resistance of the cast clasps of removable partial dentures. The different commercial types of metals used included five cobalt-chromium alloys, pure titanium, one titanium alloy (Ti-6A1-4V) and one gold alloy (type IV) that was either unhardened or age-hardened (n = 5 per group). The test method used was a constant-deflection fatigue test in which the force required to deflect the clasp for 0.6 mm and the number of loading cycles required to fracture the clasp were determined. The fatigue fracture surface of the clasps was examined with a scanning electron microscope. The results revealed that a fatigue fracture occurred in the cobalt-chromium clasp after approximately 25,000 loading cycles, in the pure titanium clasps after 4500 loading cycles, in the titanium alloy clasp after 20,000 loading cycles, and in the gold alloy clasp after 21,000 loading cycles. The means differed significantly (p < 0.001). Activation of the clasp by bending it 0.5 mm increased the fatigue resistance of the cobalt-chromium alloy and gold alloy clasps but decreased the fatigue resistance of both pure titanium and titanium alloy clasps (p < 0.005). The results of this study suggest that significant differences exist in the fatigue resistance of removable denture clasps made from different commercial cast metals, which may cause loss of retention of the removable partial denture and clasp failures.

Does disordered upper gastrointestinal motility predispose to Helicobacter pylori colonization of the stomach in children?

Helicobacter pylori is an important factor in the pathogenesis of chronic gastritis and gastroduodenal ulcer disease. However, the basic causal mechanisms of H pylori colonization on the gastric mucosa are still unclear. The authors evaluated the prevalence of H pylori colonization in 266 children who underwent upper gastrointestinal endoscopy during a 12-month period. The indications for endoscopy were follow-up of esophagitis related to gastroesophageal reflux (n = 17), suspicion of gastroesophageal reflux (n = 51), abdominal pain (n = 28), vomiting (n = 30), follow-up of esophageal atresia (n = 46) and duodenal atresia (n = 28), inflammatory bowel disease (n = 28), and miscellaneous (n = 38). The methods used to detect H pylori colonization were histology and the rapid urease test. H pylori colonization was demonstrated in 31 (11.6%) of the 266 patients. In two patient groups, a high prevalence of colonization was identified. In patients with an operated duodenal atresia, 36% (10 of 28) had H pylori on the gastric mucosa. The organism was demonstrated on the gastric mucosa in 47% (8 of 17) of the patients with gastroesophageal reflux-related esophagitis; five of the eight patients had neurological impairment. In the other patient groups, the prevalence of H pylori infection ranged from 2% to 14%. The present study suggests that, in children, the disturbed esophagogastroduodenal motility, which is commonly associated with gastroesophageal reflux and duodenal atresia, predisposes to H pylori infection.

Duodenal atresia: late follow-up.

In this study, 41 randomly chosen patients aged 15 to 35 years (mean 22 years) were carefully examined. As primary operations there were 13 membrane excisions, five duodenoduodenostomies, 22 duodenojejunostomies, and one gastrojejunostomy. Twenty-eight patients were symptom-free, ten admitted some discomfort, three had major pains, including one with a history of duodenal ulcer. Reoperation for adhesion ileus had been performed in six patients, in the early postoperative phase in one instance. At late follow-up barium meals (N = 41) showed completely normal findings in two cases only, hiatal hernia in two, gastritis in three, duodenogastric reflux in 12, slight dilation of the duodenum with good emptying and no reflux in 16, a huge duodenal sac in nine, diminished peristalsis in eight, delayed emptying in five, slight luminal narrowing in three, duodenal diverticuli in nine, bezoars in two, and a polyp in the duodenum of one patient. Ultrasound (N = 35) revealed a gallbladder septum in one patient and a dilated common bile duct in another; in one subject the gallbladder was not visualized satisfactorily. Isotope biligraphy (N = 15) showed biliary reflux to the stomach in 12 cases. Endoscopy (N = 20) findings were: esophagitis (1), hiatal hernia (2), gastric mucosa in the lower esophagus (2), biliary reflux (9), gastritis (7), gastric polyps (2), dilated duodenum of variable degree (19), diminished peristalsis (4), marked retention (2), abnormal papilla (3), diverticuli (4), and a persistent membrane (1). Histology showed superficial gastritis in three patients. E coli was cultured from the duodenal juice in five patients and Candida found in two.(ABSTRACT TRUNCATED AT 250 WORDS)