Examination of the physical state of chlorhexidine within viscoelastic, bioadhesive semisolids using Raman spectroscopy

This study examined the effects of polymeric components on the physical state of chlorhexidine within bioadhesive, semisolid formulations using Raman spectroscopy. Semisolid formulations were prepared in which chlorhexidine base (CHX, 5%w/w, particle size

Ultrastructural observations on rhabdite formation in the planarian, Artioposthia triangulata

The epidermis of the predatory terrestrial flatworm. Artioposthia triangulata has been examined by transmission electron microscopy for the presence of rhabdiform secretions. Two types of secretion are present: epidermal rhabdoids, produced by a special type of epidermal cell and true adenal rhabdites produced by gland cells beneath the epidermis. The epidermal rhabdoids are formed from Golgi-derived vesicles, which Fuse together to form the developing rhabdoid. Within the latter is a filamentous network on which granular material is deposited and coalesces to form a rod-shaped inclusion. The rhabdoids accumulate in the apical region of the cell and release their contents from the apical surface. The adenal rhabdites are formed by Golgi-derived vesicles. which become more elongated and their contents more electron-dense as they mature. The vesicles Fuse together to form the primordial rhabdite, which continues to lengthen with the addition of further vesicles. The neck of the rhabdite-forming cell passes between the muscle layers and through the basement membrane to open into the base of the epidermal cell. The rhabdites move from the cell body through the neck into the cytoplasm of the epidermal cell and make their way to the apical surface where they are released to the exterior.

Protein kinases C: potential targets for intervention in diabetic nephropathy

Protein kinases C are a family of serine threonine protein kinases that play key roles in extracellular signal transduction. Inappropriate activation of protein kinase C has been implicated in the pathophysiology of many diseases, including diabetes mellitus. Indeed, protein kinase C activation may contribute not only to the pathogenesis of diabetic complications such as nephropathy and retinopathy, but also to insulin resistance. Growing awareness that protein kinase C isoforms subserve specific subcellular functions has led to the development of isoform-specific inhibitors, which may be useful investigational tools and therapeutic agents for attenuating the effects of inappropriate protein kinase C activity. Here we review the role played by protein kinases C in diabetic nephropathy and the recent progress that has been made to modulate its activity using specific inhibitors. Curr Opin Nephrol Hypertens 7:563-570. (C) 1998 Lippincott Wiiliams & Wilkins.

Cognitive and task-related EEG correlates of arithmetic performance in adolescents

Cognitive and neurophysiological correlates of arithmetic calculation, concepts, and applications were examined in 41 adolescents, ages 12-15 years. Psychological and task-related EEG measures which correctly distinguished children who scored low vs. high (using a median split) in each arithmetic subarea were interpreted as indicative of processes involved. Calculation was related to visual-motor sequencing, spatial visualization, theta activity measured during visual-perceptual and verbal tasks at right- and left-hemisphere locations, and right-hemisphere alpha activity measured during a verbal task. Performance on arithmetic word problems was related to spatial visualization and perception, vocabulary, and right-hemisphere alpha activity measured during a verbal task. Results suggest a complex interplay of spatial and sequential operations in arithmetic performance, consistent with processing model concepts of lateralized brain function.

In situ FTIR spectroscopic studies of the oxidation of CO adsorbates on Ru(0 0 0 1) electrodes under open circuit conditions

This paper reports the first observation, using in situ FTIR spectroscopy, of the oxidation of CO adsorbates on the Ru(0001) electrode to CO under open circuit (oc) conditions in both perchloric acid and sulphuric acid solution at 20 and 55 °C. While the significant oc oxidation of the adsorbed CO on the Ru(0001) electrode was observed in perchloric acid solution, much less oc oxidation took place in sulfuric acid solution due to the specific adsorption of bisulfate at the Ru surface which inhibits the surface oxidation and reduces the reactivity of the surface towards the oxidation of CO . The oc oxidation of the CO depends strongly on the oxygen concentration in the solution and the temperature. The data so obtained are compared to those observed at the gas|solid interface, as well as to those obtained from the electro-oxidation of CO , and possible new catalytic oxidation reaction mechanisms are discussed. In addition, it is shown that the C-O frequency of the adsorbed CO may be used as an effective probe of the open circuit potential. © 2003 Elsevier B.V. All rights reserved.

Group work in elementary science:Towards organisational principles for supporting pupil learning

Group work has been promoted in many countries as a key component of elementary science. However, little guidance is given as to how group work should be organised, and because previous research has seldom been conducted in authentic classrooms, its message is merely indicative. A study is reported, which attempts to address these limitations. Twenty-four classes of 10-12-year-old pupils engaged in programmes of teaching on evaporation and condensation, and force and motion. Both programmes were delivered by classroom teachers, and made extensive use of group work. Pupil understanding progressed from pre-tests prior to the programmes to post-tests afterwards, and results suggest that group work played a critical role. Organisational principles are extrapolated from the findings, which could be readily adopted in classrooms. © 2007 Elsevier Ltd. All rights reserved.

Complex organic molecules in protoplanetary disks

Context. Protoplanetary disks are vital objects in star and planet formation, possessing all the material, gas and dust, which may form a planetary system orbiting the new star. Small, simple molecules have traditionally been detected in protoplanetary disks; however, in the ALMA era, we expect the molecular inventory of protoplanetary disks to significantly increase.

Aims. We investigate the synthesis of complex organic molecules (COMs) in protoplanetary disks to put constraints on the achievable chemical complexity and to predict species and transitions which may be observable with ALMA.

Methods. We have coupled a 2D steady-state physical model of a protoplanetary disk around a typical T Tauri star with a large gas-grain chemical network including COMs. We compare the resulting column densities with those derived from observations and perform ray-tracing calculations to predict line spectra. We compare the synthesised line intensities with current observations and determine those COMs which may be observable in nearby objects. We also compare the predicted grain-surface abundances with those derived from cometary comae observations.

Results. We find COMs are efficiently formed in the disk midplane via grain-surface chemical reactions, reaching peak grain-surface fractional abundances similar to 10(-6)-10(-4) that of the H nuclei number density. COMs formed on grain surfaces are returned to the gas phase via non-thermal desorption; however, gas-phase species reach lower fractional abundances than their grain-surface equivalents, similar to 10(-12)-10(-7). Including the irradiation of grain mantle material helps build further complexity in the ice through the replenishment of grain-surface radicals which take part in further grain-surface reactions. There is reasonable agreement with several line transitions of H2CO observed towards T Tauri star-disk systems. There is poor agreement with HC3(N) lines observed towards LkCa 15 and GO Tau and we discuss possible explanations for these discrepancies. The synthesised line intensities for CH3OH are consistent with upper limits determined towards all sources. Our models suggest CH3OH should be readily observable in nearby protoplanetary disks with ALMA; however, detection of more complex species may prove challenging, even with ALMA "Full Science" capabilities. Our grain-surface abundances are consistent with those derived from cometary comae observations providing additional evidence for the hypothesis that comets (and other planetesimals) formed via the coagulation of icy grains in the Sun's natal disk.

A rapid PCR-based assay for identification of cryptic Myotis spp. (M. mystacinus, M. brandtii and M. alcathoe)

The development of a quick PCR-based method to distinguish European cryptic Myotis spp., Myotis mystacinus, Myotis brandtii and Myotis alcathoe is described. Primers were designed around species-specific single nucleotide polymorphisms (SNP's) in the ND1 mitochondrial gene, and a pair of control primers was designed in the 12S mitochondrial gene. A multiplex of seven primer combinations produces clear species-specific bands using gel electrophoresis. Robustness of the method was tested on 33 M. mystacinus, 16 M. brandtii and 15 M. alcathoe samples from across the European range of these species. The method worked well on faecal samples collected from maternity roosts of M. mystacinus. The test is intended to aid collection of data on these species through a rapid and easy identification method with the ability to use DNA obtained from a range of sources including faecal matter.