Search Results - (Author, Cooperation:J. Collett)

2013-05-11

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Aerosols ; Atmosphere/*chemistry ; Catalysis ; *Climate ; *Dust ; Minerals/chemistry ; Oxidation-Reduction ; Sulfur Dioxide/*chemistry ; Transition Elements

article

1982

Computerunterstützter Unterricht ; Grammatik ; Zeitenfolge ; Fremdsprachenunterricht ; Französisch

The modern language journal, Bd. 66 (1982) H. 2, S. 170-179, 0026-7902

English

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background : Azathioprine and mercaptopurine (MP) are well established treatments for inflammatory bowel disease but they have severe adverse effects that prevent their use in some patients. The likelihood and type of adverse effect may relate to thiopurine methyltransferase (TPMT) enzyme activity and genotype.Aim : To compare the TPMT genotype frequencies in patients with inflammatory bowel disease who have had severe adverse effects to those who tolerate azathioprine or MP (controls).Methods : Patients with inflammatory bowel disease who had been treated with azathioprine or MP in Christchurch between 1996 and 2002 were identified. Patients with adverse effects, and controls, were invited to provide a peripheral blood sample for analysis of TPMT genotype. The genotype frequencies were then compared between the two groups.Results : Fifty-six patients were identified with adverse effects requiring cessation of therapy, of which 50 were genotyped. Reactions included allergic-type (25%), hepatitis (33%), nausea/vomiting (14%), bone marrow suppression (10%), pancreatitis (6%) and other (12%). Five of 50 patients with reactions had TPMT genotype *1/*3, one had *3/*3, and the rest had the wildtype genotype *1/*1. The patient with genotype *3/*3 had severe pancytopenia requiring hospitalization. Three of 50 controls had the *1/*3 genotype and the rest were *1/*1.Conclusions : The TPMT allele frequency in our population with inflammatory bowel disease is similar to that reported elsewhere. There was a slight trend for more frequent TPMT mutations in the patients with adverse reactions, but this was not statistically significant. Most patients with reactions did not have gene mutations.

Electronic Resource

1572-8412

Springer Online Journal Archives 1860-2000

Computer Science

Media Resources and Communication Sciences, Journalism

Electronic Resource

1573-0662

In-cloud scavenging ; gas scavenging ; aerosol scavenging ; cloudwater ; annular denuder ; NH3 ; HNO3 ; SO2

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Geosciences

Abstract An in-cloud scavenging case study of the major ions (NH4 +, SO4 2- and NO3 -) determining the cloudwater composition at a mountain site (1620 m.a.s.l.) is presented. A comparison between in-cloud measurements of the cloudwater composition, liquid water content, gas concentrations and aerosol concentrations and pre-cloud gas and aerosol concentrations yields the following results. Cloudwater concentrations resulted from scavenging of about half of the available NH3, aerosol NH4 +, aerosol NO3 -, and aerosol SO4 2-. Approximately a third of the SO2 was scavenged by the cloudwater and oxidized to SO4 2-. Cloud acidity during the first two hours of cloud interception (pH 3.24) was determined mostly by the scavenged gases (NH3, SO2, and HNO3); aerosol contributions to the acidity were found to be small. Observations of gas and aerosol concentrations at three elevations prior to several winter precipitation events indicated that NH3 concentrations are typically half (12–80 %) of the total (gas and aerosol) N (-III) concentrations. HNO3 typically is present at much lower concentrations (1–55 %) than aerosol NO3 -. Concentrations of SO2 are a substantial component of total sulfur, with concentrations averaging 60 % (14–76 %) of the total S (IV and VI).

Electronic Resource

1435-1536

Oxybutylene/oxyethylene triblockcopolymer ; micellisation ; gelation properties

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract A triblock-copoly(oxybutylene/oxyethylene), denoted E58 B17 E58 (80 wt-% E), was prepared by sequential anionic copolymerisation and its micellar and gelation properties in aqueous solution were determined. The oxybutylene/oxyethylene copolymer had the advantage over comparable oxypropylene/oxyethylene copolymers of greater uniformity of composition and chain length. The methods generally used were surface tension, light scattering intensity, photon correlation spectroscopy, together with observation of gelation. Measurements were made at 30°, 40° and 55° C over a full concentration range from dilute solution into the gel (〉200 g dm−3) and at specified concentrations, including the gel, over the temperature range from 10° to 70° C. The lower and upper temperature boundaries of the gel region were identified, and the occurrence of syneresis was noted. The properties investigated and discussed include critical micelle and gel concentrations, micellar weights and sizes, and structures and mobilities in the gel.

Electronic Resource

1573-2932

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract Gas and aerosol measurements were performed at 3 ground based measuring sites at Mt. Rigi in central Switzerland during 2 winter seasons. Both NH3 and NH4 + show a strong vertical concentration gradient between the top station (1620 masl) and the bottom station (430 masl). High concentrations of NH3 with values up to 29 ppbv, were found at the bottom station. HNO3 concentrations were usually below 1 ppbv, with lower values at the bottom station than at the top station that presumably reflect particulate NH4NO3 formation due to high NH3 concentrations at the lower site. No vertical concentration gradient was found for SO2. Simple models have been used to estimate below-cloud scavenging of gaseous NH3 and particulate NH4 + by rain between two sites with a vertical separation of 600 m. The calculations used measurements from three case studies. Below-cloud scavenging of NH3 by rain was found to be more important than below-cloud NH4 + scavenging. From 58 to 88 % of the increase of [NH4 +] in precipitation between the two sampling sites was calculated to result from gas scavenging. Both observations and scavenging calculations were in relatively good agreement for three events. Observations from the present study and tests using different aerosol and raindrop diameters in the calculations point to the importance of using real data in below-cloud scavenging studies considering the relative importance of aerosol and gas scavenging.

Electronic Resource

1573-2932

cloud chemistry ; precipitation chemistry ; aerosol scavenging ; mixed phase clouds ; cloud microphysics ; riming ; snow

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract The role clouds play as processors of atmospheric aerosols and trace gases was studied along the slope of Mt. Rigi in central Switzerland. Upon cloud formation many aerosols and trace gases are efficiently scavenged by cloud drops. The cloud drops can enhance removal of pollutants from the atmosphere by transferring them to snow or rain which falls rapidly to the ground. This often occurs through a process known as riming, where falling ice crystals capture cloud drops. When ice crystals are grown primarily via water vapor deposition, without significant capture of cloud drops, however, the cloud drops isolate atmospheric pollutants from the precipitation process, thereby inhibiting their deposition. Increased riming results in increased precipitation ion concentrations. The extent of ice crystal riming at times exhibits spatial inhomogeneities with greater riming apparent near the mountain summit. Variations in cloud chemistry with drop size indicate that bulk cloudwater composition is not an accurate predictor for the composition of cloud drops captured by the ice crystals.

Electronic Resource

1573-2932

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract Wet deposition plays an important role as a mechanism for cleansing of the polluted troposphere. Fluxes of pollutants from the atmosphere to earth's surface can affect soil and aquatic ecosystems. The investigation of the pollutant incorporation into wet deposition is therefore of considerable interest for environmental research. The project “Winter precipitation at Mount Rigi” addresses the processes determining the chemical composition of wet deposition through an integrated approach considering atmospheric physical and chemical processes and their complex interactions. The investigated topics include: aerosol and gas scavenging, atmospheric chemistry (cloud water chemistry), cloud physics and dynamics. The design of the experiment, using three ground based measuring stations at the northwestern slope of the mountain, and the conceptual ideas using case study investigations are discussed.

Electronic Resource