Effect of water on the reduction of NOx with propane on Fe‐ZSM‐5. An FTIR mechanistic study

Adsorption of NO on Fe‐ZSM‐5 leads to formation of Feⁿ⁺–NO (n = 2 or 3) species (1880 cm^-1), Fe²⁺(NO)₂ complexes (1920 and 1835 cm^-1) and NO⁺ (2133 cm^-1). Water strongly suppresses the formation of NO⁺ and Feⁿ⁺(NO)₂ and more slightly the formation of Feⁿ⁺ –NO. Introduction of oxygen to NO converts the nitrosyls into surface nitrates (1620 and 1575 cm^-1) and this process is almost unaffected by water. The nitrates are thermally stable up to ca. 300^°C, but readily interact with propane at 200^°C, thus forming surface C–H–N–O deposit (bands in the 1700–1300 cm^-1 region). Here again, water does not hinder the process. The C–H–N–O deposit is relatively inert (it does not interact with NO or NO + O₂ at ambient temperature) but, at temperatures higher than 250 °C, it is decomposed to NCO^- species (bands at 2215 (Fe–NCO) and 2256 cm^-1 (Al–NCO)). In the presence of water, however, the Fe–NCO species only are formed. At ambient temperature the NCO^- species are inert towards NO and O₂, but easily react with a NO + O₂ mixture. The mechanism of the selective catalytic reduction of nitrogen oxides on Fe‐ZSM‐5 and the effect of water on the process are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pharmacokinetic/pharmacodynamic evaluation of systemic effects of flunisolide after inhalation

The pharmacokinetics and pharmacodynamics of flunisolide were studied in healthy volunteers after inhalation. In the morning on the day the study began, volunteers inhaled 0.5 mg of flunisolide with and without oral administration of charcoal, or 1 mg, 2 mg, and 3 mg of flunisolide with concomitant administration of charcoal. A placebo group was used to assess the endogenous cortisol, granulocyte, and lymphocyte baseline levels. Flunisolide plasma levels were determined by high-performance liquid chromatography using a tandem mass spectrometer as detector (HPLC/MS/MS). Cortisol plasma levels and differential white blood cell counts were obtained over 12 hours. An integrated pharmacokinetic/pharmacodynamic (PK/PD) model was applied to link the flunisolide plasma concentrations with the effects on lymphocytes, granulocytes, and cortisol. Maximum concentration levels of 3 to 9 ng/mL of flunisolide were observed after 0.2 to 0.3 hours for all of the investigated doses. The terminal half-life ranged from 1.3 to 1.7 hours. There was no statistical difference between treatments in the presence or absence of orally administered charcoal. The pharmacokinetic/pharmacodynamic (PK/PD) models satisfactorily described the time-courses of the effects on granulocytes, lymphocytes, and cortisol suppression. The resulting E50-values (concentrations to induce 50% of the maximum effect) concurred with the reported values of in vitro receptor binding affinities. The duration of the systemic effects were short because of the short half-life of the drug. Cumulative cortisol suppression increased with dose administration and ranged from 20% to 36%. The PK/PD simulations resulted in a smaller degree of cortisol suppression for the drug administered at 10 PM. The cumulative change from baseline was slightly smaller for the effects on granulocytes and lymphocytes than those on cortisol. This information promotes the comparison with other inhaled glucocorticoids.     

Cytokine repertoire during maturation of monocytes to macrophages within spheroids of malignant and non-malignant urothelial cell lines

Terminal maturation of human blood monocytes to macrophages (MAC) in vivo is believed to be important for the morphology, antigen expression and functional activity of the resulting MAC population. This process is modulated by the specific tissue micro-environment to which blood monocytes migrate upon leaving the vasculature. Tumor-associated macrophages (TAM) are a special type of MAC, and little is known about the modulating capacity of the tumor environment on monocyte-to-MAC differentiation. By co-culturing 3-dimensional multicellular spheroids (MCS) of the urothelial-bladder-carcinoma cell lines J82 and RT4 with human monocytes/MAC we generated TAM in vitro. For comparison, monocytes/MAC were co-cultured with the non-tumorigenic urothelial cell line HCV29. The effects on monocyte differentiation were analyzed, particularly with respect to cytokine release. Monocyte maturation was modulated within the tumor spheroid dependent upon the tumor cell type. Monocytes co-cultured with MCS of the poorly differentiated J82 carcinoma spontaneously produced high amounts of IL-1beta and IL-6, but only low amounts of TNF-alpha, which could be further increased by the addition of LPS. This cytokine pattern is characteristic for monocytes and remained constant for up to 8 days in J82-MCS co-cultures. However, in RT4-MCS and HCV29-MCS co-cultures, the initial cytokine pattern changed and after 8 days corresponded well to that of MAC differentiated in vitro without tumor contact. In addition to functional parameters, we analyzed the morphology of J82-MCS-TAM and found that they displayed a monocyte-like morphology. Our data indicate that (1) tumor cells can influence monocyte-to-MAC differentiation, giving rise to TAM with monocyte-specific phenotypic properties; and (2) this capacity is dependent on the type of tumor cell.     

Role of Promoters on Tungstated Zirconia Catalysts

The isomerization of straight-chain alkanes is effectively catalyzed by tungstated zirconia promoted by Pt or Pt and Fe. In the present paper, it is attempted to better understand the role of these promoters. The materials were characterized by CO chemisorption and by transmission electron microscopy (TEM) in combination with EDX, and their catalytic performance was tested by the isomerization of n-pentane to isopentane in the presence of H₂. At low calcination temperature, very high Pt dispersion is observed with Pt atoms/clusters being embedded in or decorated by oxide material. The highly dispersed Pt moieties appear to catalyze the hydrogenolysis reaction, thus leading to low isoalkane selectivities. Higher calcination temperatures yield larger Pt particles (lower dispersion), which results in high catalytic activity and selectivity toward the isoalkane target product. It is inferred that the dissociative H₂ chemisorption occurs on the Pt particles and facilitates the reduction of the surface tungstate, which is responsible for the dehydrogenation and isomerization of n-alkane. The role of the additional promoter iron oxide still remains unresolved.     

Comparison of methods for assessing reverse osmosis membrane treatment of shrimp process water

Interest in reuse of process water from the food industry has reinforced the importance of controlling and monitoring the effectiveness and reliability of treatment systems regarding removal of organic matter and microorganisms. The ability of adenosine triphosphate bioluminescence, conductivity, turbidometry, absorbance, and multichannel fluorescence spectroscopy for indirectly monitoring the integrity of a reverse osmosis membrane when treating process water recovered from peeling in a shrimp processing line was evaluated. This study demonstrated that reverse osmosis was capable of removing bacteria (ca. 7 log CFU ml(-1)) to the levels required by the regulatory authorities for water recycling within the same food unit operation. Adenosine triphosphate and turbidometry showed a higher sensitivity for detecting compromising conditions at the treatment system (0.1% concentration of feed in permeate) and a better correlation with the aerobic count at lower levels than the other methods investigated. The sensitivity for assessing membrane integrity of conductivity and multichannel fluorescence was 1% of feed in permeate. Impact of feed variations was best leveled out in the permeates for turbidity measurements. Multichannel fluorescence spectroscopy may require laborious calibration procedures and expertise regarding data analysis and interpretation of results, which are not always available in food industries. Absorbance did not respond to changes in membrane integrity and was not well correlated to the aerobic count because of the poor sensitivity of this method for these purposes.     

Das elektromagnetische Feld eines Leitkabels zur automatischen Kursregelung von Schiffen

Übersicht Zwei parallele Ebenen unterteilen den Raum in die Schichten Erde, Wasser, Luft. Im Erdreich ist ein unendlich langes, gerades, von niederfrequentem Wechselstrom durchflossenes Kabel (Leitkabel) verlegt, das die Positionsbestimmung von Schiffen ermöglicht. Berechnet wird das elektromagnetische Feld in allen Medien, im Hinblick auf die Anwendung insbesondere im Lutraum. Der Fall großer Abstände zwischen Kabel und Aufpunkt wird gesondert behandelt, sowie die Frage des Rückstromes und der Anordnung der Spannungsquelle erörtert. Für zwei wichtige Fälle wird der örtliche Verlauf der magnetischen Feldkomponenten numerisch angegeben.

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The electromagnetic field round a pilot cable

Contents Two parallel planes divide the space into the layers: earth, water, air. An infinite straight cable carrying a low frequency alternating current (pilot cable) is laid in the earth allowing the determination of the position of ships. The electromagnetic field is calculated for all media, in particular with regard to the application in air. The case of large distances between cable and observer is treated separately. The problem of the return current and the positioning of the voltage source is discussed. For two important cases the components of the magnetic field with respect to a space coordinate are given numerically.

     

Detection of dysplastic lesions by fluorescence in a model of colitis in rats after previous photosensitization with 5-aminolaevulinic acid

Fetal nuchal translucency can be measured in most pregnant women in the first and early second trimester. The size of translucency varies slightly with gestational age and crown rump length and is independent of maternal age. Most authors have used a nuchal thickness of > or = 2.5 mm or > or = 3 mm to define abnormal, although some have suggested that the normal variation with gestation requires that different thresholds be used at different gestational ages. The accuracy of nuchal translucency measurement varies between examiners and between patients, likely in relation to examiner skill and image resolution. The small size of a nuchal translucency, less than 3 mm in most cases, probably approximates the threshold of normal interexaminer and intraexaminer variability. The presence of a thickened nuchal translucency is associated with chromosomal abnormality and perhaps with structural abnormality even when the karyotype is normal. Because of the reported variations in the populations studied, the methods used, and the results of screening, it is inappropriate at this time to assign a numeric risk to any individual patient with this finding. However, in both high-risk and low-risk groups, the positive predictive value appears to be high enough that patients with increased nuchal translucency should be counseled by their obstetrician and prenatal diagnostic testing should be offered. Because early genetic diagnosis by CVS has a substantially higher procedure-associated loss rate than amniocentesis in the second trimester, many patients may elect to wait for chromosomal testing. If so, disappearance of nuchal thickening should not be taken as reassurance. As a screening test to be widely applied to a general or low-risk population, the utility of fetal nuchal translucency measurement is uncertain. The reported sensitivity for identification of trisomy 21 has ranged from about 40% to 80%, and the sensitivity for identification of other aneuploidies may be lower than for Down's syndrome. From a cost-risk-benefit standpoint, universal first-trimester ultrasound screening has not been appropriately compared with standard risk assessment using maternal age and multiple-marker serum screening, with amniocentesis as the predominant diagnostic method. Also, the issues of availability and reimbursement have not been addressed. Currently, measurement of nuchal translucency is not a substitute for the standard of obstetrical care, which is to offer multiple-marker serum screening to every pregnant woman at 15 to 20 weeks. Similarly, it is inappropriate to substitute nuchal translucency measurement for genetic counseling and CVS or amniocentesis in women above 35 years of age or those with a significant positive history. Finally, the data are not clear as to whether a normal nuchal translucency decreases the likelihood of chromosomal abnormality in a high-risk population, and such women should not be discouraged from invasive testing because of a normal first-trimester ultrasound study. The data supporting the association between thickened nuchal transluency and chromosomal abnormality are compelling, but further study is needed before adopting routine nuchal translucency screening. Combining first-trimester ultrasonography with early serum screening is currently being investigated and may ultimately prove to be the most efficient means of screening for chromosomal anomaly.