Current Tasks and Challenges for Exhaust Aftertreatment Research. A Viewpoint from the Automotive Industry

Automotive emission control through modern engine design and active exhaust gas aftertreatment has reached a very high technological level. This led to a considerable decrease of exhaust emissions from automobiles in the last years, despite continuous increase of vehicle numbers and kilometres travelled. Nevertheless, a number of challenges for scientists and engineers remain, to develop further improved catalyst materials and exhaust aftertreatment systems. The paper describes the state of the art of exhaust aftertreatment and the major technological paths that will be followed in further development. It concentrates mainly on aftertreatment systems to achieve near zero emissions for vehicles in especially emissions sensitive regions and on exhaust aftertreatment technologies for lean burn engines, with a special emphasis on nitrogen oxides and particulates. These engines and therefore these aftertreatment systems will be mandatory to fulfil the requirements on CO₂ reduction.     

The dose-dependent effects of oral premedication with midazolam

OBJECTIVE: The aim of this study was to examine the psychological effects, well-being and side effects after various doses of oral midazolam medication. METHODS: After informed consent has been obtained and following the approval by the institutional ethical committee, 80 adult patients in the ASA physical status I and II were randomly assigned to one of five different premedication groups: 3.75, 7.5, 11.25, 15 mg midazolam, and placebo. The medication was given in a double-blind fashion 60 min before induction of general anaesthesia for various surgical procedures. At 3 definite stages (before premedication, 30 and 60 min after premedication), blood pressure, heart rate, transcutaneous oxygen saturation and respiratory rate were measured. Sedation and well-being were graded according to a 5-point scale, and the subjective anxiety level was assessed according a visual analogue scale (range 0-100 mm). Anterograde and retrograde amnesia were measured by recall of auditive and visual stimuli. Finally, patients were asked whether in case of future surgery they would prefer the same or a different medication. RESULTS: Demographic data were similar in all groups. There was no significant difference in respiratory rate, oxygen saturation, blood pressure or heart rate. Alertness declined only after 60 min in the groups treated with 7.5 mg and more midazolam. During the entire measurement period, anxiolysis was not different from placebo in any of the midazolam groups. In comparison to placebo, all midazolam groups showed a statistically significant and dose dependent anterograde amnesia for visual stimuli. Subjective well-being scores showed no differences between the groups. Only few side effects were seen following doses of 7.5 mg and higher, including ptosis, strabismus, diplopia, speech disorders, disorientation and vertigo. The majority of patients in all groups indicated a wish for the same medication in case of future anaesthesia for surgical interventions. CONCLUSIONS: Midazolam administered orally prior to surgical procedures showed marked interindividual variability. Sedation and amnesia were dose-dependent and were evaluated by the patients as acceptable. Anxiolysis was not significantly different from placebo. A dose of 7.5 mg midazolam showed the best relation between desirable and undesirable effects. Adequate attention given to the patient by the anaesthesiologist prior to surgery seems to be as important and beneficial as oral medication with midazolam.     

Selective inhibition of hepatic collagen accumulation in experimental liver fibrosis in rats by a new prolyl 4-hydroxylase inhibitor

In order to detect and characterize allergen-specific T cells in the airways of atopic asthmatics, we measured proliferation and cytokine production by bronchoalveolar lavage (BAL) T cells isolated from Dermatophagoides pteronyssinus (Der p)-sensitive asthmatics and nonatopic control subjects, and compared the results with those generated using peripheral blood (PB) T cells. BAL and PB mononuclear cells were collected 24 h after segmental allergen challenge by fibreoptic bronchoscopy and venepuncture, respectively. T cells purified from BAL and PB were stimulated with autologous, irradiated antigen-presenting cells and D. pteronyssinus extract or a control, nonallergen antigen (M. tuberculosis purified protein derivative [PPD]). IL-5 and IFN-gamma concentrations were measured in culture supernatants by ELISA, and T-cell proliferation by 3H-thymidine uptake. D. pteronyssinus-induced proliferation of T cells derived from both BAL and PB was elevated in asthmatics when compared with control subjects (p < 0.05), whereas PPD-induced proliferation was equivalent in both compartments. In the asthmatics, D. pteronyssinus-induced proliferative responses of equivalent numbers of BAL and PB T cells obtained after allergen challenge were statistically equivalent. Nevertheless, BAL T cells stimulated with D. pteronyssinus produced significantly greater amounts of IL-5 than did PB T cells (p < 0.05). Allergen-induced proliferation and IL-5 production by BAL T cells in the asthmatics after segmental allergen challenge correlated with the percentages of eosinophils in the BAL fluid (p < 0.01). Further, BAL T cells from asthmatic patients produced significantly higher amounts of IL-5 than did the same number of cells from nonatopic control subjects (p < 0.05). We conclude that, in D. pteronyssinus-sensitive asthmatics, allergen-specific T cells can be detected in the bronchial lumen after allergen challenge and that allergen-induced proliferation and IL-5 production by these cells correlates with local eosinophil influx. Although bronchial luminal T cells show an equivalent proliferative response to allergen stimulation as compared with PB T cells, they do produce more IL-5, consistent with the hypothesis that local differentiation or priming of these cells within the bronchial mucosal environment results in upregulation of allergen-induced IL-5 secretion.     

Thermal effects in modulated IMPATT oscillators

The modulation sensitivity and the inherent a.m. percentage of IMPATT oscillators with internal current modulation were measured as a function of the modulation frequency in the range 10Hz-1 MHz. Although constant above 100kHz, both quantities were found to vary with the modulation frequency below 100kHz. Assuming thermal effects as the origin of these variations, the possible relative change of the modulation sensitivity was calculated to be about 20%, taking into account the temperature dependence of the ionisation coefficient and of the drift velocity. With Q factors ranging between 20 and 150, the modulation sensitivity varied between 3 and 0.3 MHz/mA, and the ratio of a.m. percentage and modulating current varied between 7 and 10% per mA.     

Pulsed quantum-cascade laser-based sensor for trace-gas detection of carbonyl sulfide

Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1sigma) of 1.2 parts per billion by measuring a well-isolated OCS P(11) absorption line in the v3 band at 2057.6 cm(-1) using an astigmatic Herriott cell of 36-m optical path length and 0.4-s acquisition time.     

An advanced quality and reliability assessment approach applied to thermal stress issues in electronic components and assemblies

A new failure analysis and reliability assessment approach has been developed, based on surface topography analysis of ICs and assemblies under thermal stress conditions. An important application concerns the assessment of the ability of ICs to withstand typical JEDEC type solder cycles without too strong stress accumulation in the components. An important advantage of this new technology is the predictive power, i.e. the delamination risk may be visualized before physical failure occurs.     

Effects of angiotensin II-receptor blockade with losartan on insulin sensitivity, lipid profile, and endothelin in normotensive offspring of hypertensive parents

BACKGROUND: Acute liver failure (ALF) secondary to malignant infiltration of the liver is rare and is diagnosed often only after death. AIMS: To determine diagnostic factors and particular clinical patterns of illness. METHODS: Review of case notes from all patients with ALF secondary to hepatic infiltration admitted to this unit over an 18 year period (1978-1995). RESULTS: From a total of 4020 admissions, 18 patients were identified with ALF attributable to hepatic infiltration. Mean age was 40.7 years. Aetiology was non-Hodgkin's lymphoma in nine patients, Hodgkin's disease in three, infiltrative metastatic carcinoma in four, and haemophagocytosis with no precipitant cause in two cases. Prodromal symptoms were non-specific, but occurred at least two to four weeks before onset of ALF, making the presence of such symptoms of value in differential diagnosis of the cause of ALF. Clinical examination and investigations were unhelpful in distinguishing these cases from more usual causes of ALF. Usually, the clinical course was of rapid deterioration and death from multiorgan failure, and only one patient survived. Diagnosis was made during life in 15 patients. Histology showed evidence of widespread hepatocellular necrosis, with diffuse infiltration by tumour cells rather than focal cellular aggregation. CONCLUSIONS: Only with accurate histological diagnosis from liver biopsy and institution of specific therapy early in the management of such patients will the best chance of recovery be achieved. In every case of ALF with prodromal symptoms or abnormal imaging, hepatic histology should be obtained by liver biopsy as soon as possible to diagnose infiltrative hepatic disease.     

Block Copolymer-Templated BiFeO3 Nanoarchitectures Composed of Phase-Pure Crystallites Intermingled with a Continuous Mesoporosity： Effective Visible-Light Photocatalysts？

Herein is reported the soft-templating synthesis of visible-light photoactive bismuth ferrite (BiFeO₃) nanoarchitectures in the form of thin films using a poly(ethylene-co-butylene)-block-poly(ethylene oxide) diblock copolymer as the structure-directing agent. We establish that (1) the self-assembled materials employed in this work are highly crystalline after annealing at 550 °C in air and that (2) neither the bismuth-poor Bi₂Fe₄O₉ phase nor other impurity phases are formed. We further show that there is a distinct restructuring of the high quality cubic pore network of amorphous BiFeO₃ during crystallization. This restructuring leads to films with a unique architecture that is composed of anisotropic crystallites intermingled with a continuous mesoporosity. While this article focuses on the characterization of these novel materials by electron microscopy, krypton physisorption, grazing incidence small-angle X-ray scattering, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, UV-vis and Raman spectroscopy, we also examine the photocatalytic properties and show the benefits of the combination of mesoporosity and nanocrystallinity. Templated BiFeO₃ thin films (25% porosity) with a direct optical band gap at 2.9 eV exhibit a catalytic activity for the degradation of rhodamine B much better than that of nontemplated samples. We attribute this improvement to the nanoscale porosity, which provides for more available active sites on the photocatalyst.