Microstructural studies on nanocrystalline oxide dispersion strengthened austenitic (Fe–18Cr–8Ni–2W–0.25Y<Subscript>2</Subscript>O<Subscript>3</Subscript>) alloy synthesized by high energy ball milling and vacuum hot pressing

In the present work, nanostructured (Fe–18Cr–8Ni–2W) austenitic base and oxide dispersion strengthened (ODS) alloy powders were produced through mechanical alloying and these nano powders were consolidated by vacuum hot pressing. The results showed that initially bcc solid solution formed in both the alloys and this transformed to fcc with continued milling. The bcc solid solution formation and the subsequent transformation to fcc were significantly faster in the ODS alloys when compared to the base alloy. In the ODS alloy, a grain size of ~25 nm is achieved within 5 h of milling. Study of variation of microhardness of mechanically alloyed powder particles with grain size showed linear Hall–Petch kind of behavior. Following vacuum hot pressing of mechanically alloyed powders, nearly fully dense (>99% of theoretical density) compacts were obtained with a grain size of ~80 nm. The bulk hardness of base and ODS alloys are ~530 and ~900 HV, respectively. These are significantly higher than the values reported in the literature so far. The enhanced strength the ODS alloy is due to increased dislocation density and presence of fine dispersoids along with the nanocrystalline grains.     

A theoretical approach to the deposition and clearance of fibers with variable size in the human respiratory tract

In the study presented here, a mathematical approach for the deposition and clearance of rigid and chemically stable fibers in the human respiratory tract (HRT) is described in detail. For the simulation of fiber transport and deposition in lung airways an advanced concept of the aerodynamic diameter is applied to a stochastic lung model with individual particle trajectories computed according to a random walk algorithm. Interception of fibrous material at airway bifurcations is considered by implementation of correction factors obtained from previously published numerical approaches to fiber deposition in short bronchial sequences. Fiber clearance is simulated on the basis of a multicompartment model, within which separate clearance scenarios are assumed for the alveolar, bronchiolar, and bronchial lung region and evacuation of fibrous material commonly takes place via the airway and extrathoracic path to the gastrointestinal tract (GIT) or via the transepithelial path to the lymph nodes and blood vessels.Deposition of fibrous particles in the HRT is controlled by the fiber aspect ratio β in as much as particles with diameters <0.1 μm deposit less effectively with increasing β, while larger particles exhibit a positive correlation between their deposition efficiencies and β. A change from sitting to light-work breathing conditions causes only insignificant modifications of total fiber deposition in the HRT, whereas alveolar and, above all, tubular deposition of fibrous particles with a diameter ≥0.1 μm are affected remarkably. For these particles enhancement of the inhalative flow rate results in an increase of the extrathoracic and bronchial deposition fractions. Concerning the clearance of fibers from the HRT, 24-h retention is noticeably influenced by β and, not less important, by the preferential deposition sites of the simulated particles. The significance of β with respect to particle size may be regarded as similar to that determined for the deposition scenarios, while breathing conditions do not have a valuable effect on clearance.     

Brominated flame retardants and dechlorane plus in the marine atmosphere from Southeast Asia toward Antarctica

The occurrence, distribution, and temperature dependence in the marine atmosphere of several alternative brominated flame retardants (BFRs), Dechlorane Plus (DP) and polybrominated diphenyl ethers (PBDEs) were investigated during a sampling cruise from the East Indian Archipelago toward the Indian Ocean and further to the Southern Ocean. Elevated concentrations were observed over the East Indian Archipelago, especially of the non-PBDE BFR hexabromobenzene (HBB) with concentrations up to 26 pg m(-3) which were found to be related to continental air masses from the East Indian Archipelago. Other alternative BFRs- pentabromotoulene (PBT), pentabromobenzene (PBBz), and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE)-were elevated, too, with concentrations up to 2.8, 4.3, and 2.3 pg m(-3), respectively. DP was detected from 0.26 to 11 pg m(-3) and bis-(2-ethylhexyl)-tetrabromophthalate (TBPH) ranged from not detected (nd) to 2.8 pg m(-3), respectively. PBDEs ranged from nd to 6.6 pg m(-3) (Σ(10)PBDEs) with the highest individual concentrations for BDE-209. The approach of Clausius-Clapeyron (CC) plots indicates that HBB is dominated by long-range atmospheric transport at lower temperatures over the Indian and Southern Ocean, while volatilization processes and additional atmospheric emissions dominate at higher temperatures. In contrast, BDE-28 and -47 are dominated by long-range transport without fresh emissions over the entire cruise transect and temperature range, indicating limited fresh emissions of the meanwhile classic PBDEs.     

Strength behaviour of flawed pipes under internal pressure and external bending moment: Comparison between experiment and calculation

Experimentally determined failure curves for pipes weakened by surface longitudinal or circumferential defects, were compared with results calculated with the aid of engineering approximation methods. Considering the scatter bands of the mechanical properties and the geometrical dimensions, then by use of the engineering approximation methods, one can make only rough estimates of the load bearing behaviour.     

In situ temperature measurement by infrared absorption for low-temperature epitaxial growth of homo- and hetero-epitaxial layers on silicon

The use of infrared transmission to measure silicon wafer temperature in a lamp-heated susceptor-free reactor is described. The relevant temperature range is 400 to 800° C, and the accuracy is on the order of a few degrees centigrade. The method is then applied towards the growth of silicon and silicon-germanium alloy layers on silicon substrates. For silicon-germanium layers typical of those used in heterojunction bipolar transistors, no change in absorption compared to that of the silicon substrates is observed.     

Obstructive sleep apnea in patients with coronary heart disease

Patients with obstructive sleep apnea have an increased cardiovascular morbidity and mortality, those with co-existent coronary artery disease being particularly at risk. The object of our study was to evaluate the prevalence of obstructive sleep apnea in patients with coronary artery disease. 153 patients (117 men, 36 women) with verified coronary artery disease were given a highly sensitive standardized questionnaire. The 59 patients with pathological results were then checked with a 6-channel non-laboratory monitoring system. 22.2% of all patients had a respiratory disturbance index (RDI) above 5/h. and 14.4% above 10/h. 13.3% had a pathological RDI and additionally suffered from excessive daytime sleepiness. Patients with coronary artery disease have a high prevalence of obstructive sleep apnea and should consequently be screened for this sleep-related breathing disorder.     

An empirical bayes strategy for analysing manufacturing data in real time

This paper discusses and develops a real-time strategy to monitor manufacturing process control data. The strategy presented in this paper is designed to intercept, analyse and monitor data as measurements are generated from a high-volume information-intensive manufacturing process. Empirical Bayes theory is used to develop a method to monitor and analyse continuous type measurements generated by a manufacturing process in real time. Several specific techniques will be proposed for detecting manufacturing process problems and examples of applying these techniques will be shown.     

Risk analysis of linear accelerator radiosurgery

PURPOSE: To evaluate the toxicity of stereotactic single-dose irradiation and to compare the own results with already existing risk prediction models. METHODS AND MATERIALS: Computed tomography (CT) or magnetic-resonance (MR) images, and clinical data of 133 consecutive patients treated with linear accelerator radiosurgery were analyzed retrospectively. Using the Cox proportional hazards model the relevance of treatment parameters and dose-volume relationships on the occurrence of radiation-induced tissue changes (edema, localized blood-brain barrier breakdown) were assessed. RESULTS: Sixty-two intraparenchymal lesions (arteriovenous malformation (AVM): 56 patients, meningioma: 6 patients) and 73 skull base tumors were selected for analysis. The median follow-up was 28.1 months (range: 9.0-58.9 months). Radiation-induced tissue changes (32 out of 135, 23.7%) were documented on CT or MR images 3.6-58.7 months after radiosurgery (median time: 17.8 months). The actuarial risk at 2 years for the development of neuroradiological changes was 25.8% for all evaluated patients, 38.4% for intraparenchymal lesions, and 14.6% for skull base tumors. The coefficient: total volume recieving a minimum dose of 10 Gy (VTREAT10) reached statistical significance in a Cox proportional hazards model calculated for all patients, intraparenchymal lesions, and AVMs. In skull base tumors, the volume of normal brain tissue covered by the 10 Gy isodose line (VBRAIN10) was the only significant variable. CONCLUSIONS: These results demonstrate the particular vulnerability of normal brain tissue to single dose irradiation. Optimal conformation of the therapeutic isodose line to the 3D configuration of the target volume may help to reduce side effects.     

Simultaneous therapy of gonorrhea with penicillin and probenecid. Serum penicillin picture

19 patient received penicillin and probenecid. The resulting serum concentrations of penicillin was determined. In regimen I 4 mill. IU depot penicillin was given i.m. simultaneously with 1 g probenecid orally. In regimen II probenecid was given 30 min prior to the administration of penicillin. In both series the average serum concentrations of penicillin were not significantly different (p = 0.01).