Basaltic rocks analyzed by the Spirit Rover in Gusev Crater

The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain 相似文献   

Chitosan in Mucoadhesive Drug Delivery: Focus on Local Vaginal Therapy

Mucoadhesive drug therapy destined for localized drug treatment is gaining increasing importance in today’s drug development. Chitosan, due to its known biodegradability, bioadhesiveness and excellent safety profile offers means to improve mucosal drug therapy. We have used chitosan as mucoadhesive polymer to develop liposomes able to ensure prolonged residence time at vaginal site. Two types of mucoadhesive liposomes, namely the chitosan-coated liposomes and chitosan-containing liposomes, where chitosan is both embedded and surface-available, were made of soy phosphatidylcholine with entrapped fluorescence markers of two molecular weights, FITC-dextran 4000 and 20,000, respectively. Both liposomal types were characterized for their size distribution, zeta potential, entrapment efficiency and the in vitro release profile, and compared to plain liposomes. The proof of chitosan being both surface-available as well as embedded into the liposomes in the chitosan-containing liposomes was found. The capability of the surface-available chitosan to interact with the model porcine mucin was confirmed for both chitosan-containing and chitosan-coated liposomes implying potential mucoadhesive behavior. Chitosan-containing liposomes were shown to be superior in respect to the simplicity of preparation, FITC-dextran load, mucoadhesiveness and in vitro release and are expected to ensure prolonged residence time on the vaginal mucosa providing localized sustained release of entrapped model substances.     

Der Einfluß der Fauna auf die Stoffverlagerung sowie die Homogenität und die Durchlässigkeit von Böden

The influence of the fauna on displacement and on homogeneity and permeability of soils The influence of the most important soil animals (mammals, ants, termites, woodlice and earthworms) on displacement and on homogeneity and permeability of soils is discussed in reference to both older and more recent literature. Nearly all soil animals cause displacement of organic and mineral soil particles. The quantity, intensity and direction of this activity depends upon the morphological characters of the species involved. The homogeneity of soils is positively influenced only by the earthworms (and related forms) whereas the activity of the other soil fauna mostly has a contrary effect as far as shorter periods are concerned. The permeability of soils increases in different dimensions due to the activity of all species discussed. Permanent vegetation and non-tilling for the most part favour the activity of the soil fauna. Recent field experiments dealing with minimum or zero tillage have made this fact fairly evident.     

Selection for immune response in goats: the antibody response to diphtheria toxoid after 12 years of selection.

A herd of Norwegian dairy goats was subject to selection for high and low antibody response to diphtheria toxoid for 12 yr, or approximately 5.5 generations because sires were used for one mating season, whereas dams were used several years. The herd comprised approximately 100 milking goats. Only sires were tested and selected, five to seven sires were used in each line each year, and the percentage of male kids used for breeding varied between 15 and 50%. The mean phenotypic values of the lines diverged until the 4th yr, but the lines did not diverge any further. The means of both lines decreased during the experimental period. The restricted maximum likelihood (REML) estimate of the heritability of the trait in the base population was .19, whereas the realized heritability approached zero in the last six cycles of selection. Using the REML-estimate of heritability in an individual animal model, the mean breeding values (BLUP) of the lines were significantly different. The difference in mean BLUP values between the lines increased throughout the study. Yet, this increase was only 40% from the 2nd to the 12th yr. No effect of a major gene was observed in a test based on individual BLUP.     

Methodology for recognition of invasive potential of Escherichia coli.

Surveillance for dysentery-related invasive potential in bacteria using the Sereny keratoconjunctivitis test is restricted by expense, time factor, and necessity for confirmation. Primary screening of isolates in a standardized mammalian cell culture system is recommended. Bacteria are grown 20 hr in veal infusion, washed, and resuspended in 20% heat-inactivated fetal bovine serum (FBS) supplemented with 0.12% brain heart infusion and 0.1% bile salts. The HeLa culture is grown 20 hr as a monolayer in chamber slides with 90% minimal essential medium (MEM)-10% FBS. The host culture is infected at a ratio of 10 bacteria/mammalian cell for 3 hr at 35 degrees C. The infection medium is replaced with MEM-FBS supplemented with 300 microng lysozyme and 5 microng gentamycin/ml. The infected monolayer is incubated 5 hr at 35 degrees C to permit intracellular multiplication. Specimens are washed, fixed with methanol, and stained successively with May-Grunwald and Giemsa dyes. Bacteria occur within the cytoplasm if invasion has occurred. The criterion for a positive test is that 1% of the host cells possesses at least 5 bacteria in 2 of 3 trials. Invasiveness is correlated with and possibly preconditioned by cytotoxic principle(s). Infectivity rates vary from 0 to 30%. The cytopathic effect is noted in 5-50% of HeLa cells. Positive results must be confirmed by the Sereny test.     

Historical and Geographical Trends in Sediment Chronology from Lakes and Marine Sites Along the Norwegian Coast

Sediment cores collected from 12 lakes and eight marine sites along the Norwegian and Svalbard coast as part of a project investigating polycyclic aromatic hydrocarbons (PAH) in sediments were dated radiometrically using ²¹⁰Pb, ¹³⁷Cs and ²⁴¹Am fallout radionuclides. In all lake cores, except on Svalbard, the ¹³⁷Cs activity versus depth profile appears to have been significantly modified by post-depositional migration within the sediment column. The relatively low ¹³⁷Cs inventories suggest that these sites were not significantly impacted by fallout from the 1986 Chernobyl accident. All the marine cores have ¹³⁷Cs inventories that are substantially lower than in lake sediments almost certainly due to leaching of ¹³⁷Cs from the marine sediments due to higher solubility in the seawater. In the marine surface sediments, the unsupported ²¹⁰Pb concentrations are up to an order of magnitude lower than in the corresponding lake sediments reflecting the higher (dry mass) sedimentation rate at the marine sites. Five of the cores including marine sites and lakes have unusual high ²¹⁰Pb flux most likely due to sediment focusing. Most of the irregularities in the ²¹⁰Pb records seem to be due to slump events but some patterns are also due to possibly increased accumulation rates. Three of the marine cores show systematic increase in their sedimentation rate from c.1960 towards the present while only one lake shows the same systematic increase.     

Obstacles associated with organizational change

This article briefly explores one view of the change process, discusses obstacles to change, the means to deal with these obstacles, and describes change principles and specific examples of change strategies that commonly work.