Nanostructured polymer blends: Synthesis and structure

Nanostructured polymer blends prepared via anionic ring opening polymerizations of cyclic monomers in the presence of a pre-made polymer melt exhibit a number of special properties over traditional polymer blends and homopolymers. Here, we report on a simple and versatile method of in situ polymerization of macrocyclic carbonates in the presence of a maleic anhydride polypropylene (mPP) matrix and a surface-active compatibilizer (i.e. PC grafted onto a mPP backbone generated in situ) to yield a micro- and nanostructured polymer blends consisting of a polycarbonate (PC) minor phase, and a polypropylene (PP) major phase. By varying the processing conditions and concentration of the macrocyclic carbonate it was possible to reduce the size of the PC dispersions to an average minor diameter of 150 nm. NMR and TEM characterizations indicate that the PC dispersions do not influence crystal content in the PP phase. Overall, the results point to a simple strategy and versatile route to new polymeric materials with enhanced benefits.     

Projection status of calbindin- and parvalbumin-immunoreactive neurons in the superficial layers of the rat's superior colliculus

Immunocytochemistry and retrograde labeling were used to define the thalamic projections of calbindin- and parvalbumin-containing cells in superficial layers of the rat's superior colliculus (SC). Quantitative analysis revealed that 90.8 +/- 2.2% (mean +/- standard deviation) of the calbindin-immunoreactive neurons in the stratum griseum superficiale (SGS) projected to the dorsal lateral geniculate nucleus (LGNd) and that 91.3 +/- 4.3% of calbindin-immunoreactive neurons in the stratum opticum (SO) projected to the lateral posterior nucleus (LP). In contrast, only 17.3 +/- 2.5% of parvalbumin-immunoreactive neurons in the SGS were found to project to the LGNd and 16.5 +/- 3.1% of the parvalbumin-immunoreactive SO cells were retrogradely labeled after LP injections. Few of the parvalbumin-immunoreactive neurons in either the SGS (7.2 +/- 2.5%) or the SO (9.2 +/- 2.5%) were GABA positive. The retrograde-labeling results suggest that parvalbumin-immunoreactive neurons in the rat's SO and SGS may either be primarily interneurons or have descending projections, while calbindin-containing cells are primarily thalamic projection neurons. These results are consistent with data from other rodents, but almost exactly the opposite of data that have been reported for the cat for these same populations of SC projection neurons. Such interspecies differences raise questions regarding the functional importance of expressing one calcium-binding protein versus another in a specific neuronal population.     

Microbiological quality of retail cheeses made from raw, thermized or pasteurized milk in the UK

Two studies of retail fresh, ripened and semi-hard cheeses made from raw, thermized or pasteurized milk were undertaken in the UK during 2004 and 2005 to determine the microbiological quality of these products. Using microbiological criteria in European Commission Recommendations 2004/24/EC and 2005/175/EC, 2% of both raw, thermized (37/1819 samples) and pasteurized (51/2618 samples) milk cheeses were of unsatisfactory quality. Raw or thermized milk cheeses were of unsatisfactory quality due to levels of Staphylococcus aureus at 10(4)cfu g(-1), Escherichia coli at 10(5)cfu g(-1), and/or Listeria monocytogenes at 10(2)cfu g(-1), whereas pasteurized milk cheeses were of unsatisfactory quality due to S. aureus at 10(3)cfu g(-1) and/or E. coli at 10(3)cfu g(-1). Salmonella was not detected in any samples. Cheeses were of unsatisfactory quality more frequently when sampled from premises rated as having little or no confidence in management and control systems, and stored/displayed at above 8 degrees C. Raw or thermized milk cheeses were also more likely to be of unsatisfactory quality when they were unripened types, and pasteurized milk cheeses when they were: semi-hard types; from specialist cheese shops or delicatessens; cut to order. These results emphasize the need for applying and maintaining good hygiene practices throughout the food chain to prevent contamination and/or bacterial growth. Labelling of cheeses with clear information on whether the cheese was prepared from raw milk also requires improvement.     

Effect of Melt‐Memory on the Crystal Polymorphism in Molded Isotactic Polypropylene

The influence of γ‐quinacridone as a β‐crystal nucleating agent in injection molded isotactic polypropylene (iPP) is discussed. Samples are injection molded and characterized via polarized‐light optical microscopy and X‐ray diffraction. Mold‐filling simulation is used to understand the shear and cooling processes during sample preparation. The cooling rate associated with the quench near the mold wall is estimated to be greater than 600 K s^?1 using simulation, confirming previous studies that β‐crystal growth is not supported at that cooling rate. The non‐nucleated samples form β‐crystals at a distance of 100–300 µm from the skin and in the core of the sample, which is not expected based on quiescent cooling data. Since the mold‐filling simulation does not predict shear in the core, the formation of the β‐crystals formed in this region is attributed to shear‐induced crystallization effects in the injection unit of the molding machine that are not modeled in flow simulation, as they are typically excluded from any molding simulation analysis. This “melt‐memory” effect has shown to be significant, and it is suggested that the prediction of final properties of injection moldings requires understanding and knowledge of the entire shear history of the material including that of the injection unit.     

Responses of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus

1. The response characteristics of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus were investigated.2. As has been noted for other mammalian species, a distinct difference between the functional organizations of the superficial and deeper layers of the superior colliculus was observed.3. Neurones in the superficial layers were exclusively visual, with small receptive-fields, and generally did not show response decrements with repeated stimulation. The sizes of the receptive-fields did not vary appreciably as a function of retinal eccentricity.4. In the deeper layers, visual receptive-fields were large, or could not be accurately delimited, and response habituation was often evident. In addition, many cells in the deeper layers of the colliculus responded only to somatosensory stimuli. Far fewer cells, which appeared to be confined to the caudal portions of the colliculus, responded to auditory stimuli. Polymodal cells were also encountered.5. Selectivity to opposing directions of movement was tested for ninety-four visual cells. Using a ;null' criterion, 27.7% of these cells were judged to be directionally selective. A distribution of the preferred directions of these cells showed a significant preference for movement with an upper-nasal component. With a statistical criterion, 60.6% of these cells were considered to show a significant asymmetry in responding to movement in opposing directions.6. Directional selectivity was also tested for ninety-two cells following acute, unilateral, lesions of the visual cortex. For the eighty cells recorded, homolateral to the ablated cortex, 27.5% were judged as directionally selective using the statistical criterion, while 12.5% were selective with the ;null' criterion. Of the twelve cells isolated in the colliculus, contralateral to the lesions, seven were judged as directionally selective with the statistical, and three with the ;null' criterion.7. The effects of visual cortical lesions upon directional selectivity appeared to be confined to cells in the superficial layers of the colliculus. It was suggested that directional selectivity of many cells in the superficial layers of the tectum of the hamster is organized cortically.8. A clear spatial correspondence was observed for the receptive-fields of visual, somatosensory, and auditory neurones.9. As has been suggested for other species, the hamster's superior colliculus appears to play an important role in orienting the animal toward visual, somatosensory, and auditory stimuli.     

Development of a Weather Forecasting Code: A Case Study

Computational science is increasingly supporting advances in scientific and engineering knowledge. The unique constraints of these types of projects result in a development process that differs from the process more traditional information technology projects use. This article reports the results of the sixth case study conducted under the support of the Darpa High Productivity Computing Systems Program. The case study aimed to investigate the technical challenges of code development in this environment, understand the use of development tools, and document the findings as concrete lessons learned for other developers' benefit. The project studied here is a major component of a weather forecasting system of systems. It includes complex behavior and interaction of several individual physical systems (such as the atmosphere and the ocean). This article describes the development of the code and presents important lessons learned.     

Synthesis and Biological Evaluation of Novel Epothilone B Side Chain Analogues

The design, synthesis, and biological evaluation of a series of epothilone analogues with novel side chains equipped with an amino group are described. Their design facilitates potential conjugation to selective drug delivery systems such as antibodies. Their synthesis proceeded efficiently via Stille coupling of a readily available vinyl iodide and heterocyclic stannanes. Cytotoxicity studies and tubulin binding assays revealed two of these analogues to be more potent than epothilones A–D and the anticancer agent ixabepilone, currently in clinical use.     

An alternative method for the quantitation of neuronal damage after experimental middle cerebral artery occlusion in rats: analysis of behavioral deficit

We tested the hypothesis that increasing durations of focal ischemia that have been shown to result in enlargement of cortical infarct will be associated with progression of behavioral dysfunction that can be measured by a battery of tests sufficiently sensitive and reproducible to detect a positive effect of pharmacotherapy. Untreated or N-methyl-D-aspartate receptor antagonist (CNS-1102)-treated spontaneously hypertensive rats underwent 45, 60, 90, or 120 min of tandem middle cerebral and common carotid artery occlusion followed by reperfusion. We then evaluated the extent of damage and its recovery for up to 21 days using nine behavioral tests aimed at analyzing strength, coordination, and bilateral asymmetry. Also using a graded bioassay that employs a curve-fitting computer program (ALLFIT) to correlate duration of ischemia with degree of behavioral dysfunction, we calculated the average of maximal behavioral dysfunction and duration of ischemia required to produce half-maximal behavioral dysfunction and compared these values in untreated controls with analogous values obtained from animals treated with CNS-1102. Three behavioral tests, forearm flex, tape (somatosensory neutralization), and foot-fault placing, were each separately and combined able to distinguish between the degrees of damage produced by increasing durations of ischemia. The behavioral abnormalities assessed using the tape test were reversible within a week, whereas those using forearm flex or foot-fault tests persisted for at least 21 days. CNS-1102 significantly reduced behavioral dysfunction measured by all three tests. This analysis of behavioral dysfunction represents a useful experimental model to grade efficacy of therapies aimed at protecting the brain from damage produced by acute stroke and might also be used to assess recovery from preexisting ischemic damage.     

Medication take-home doses and contingency management.

Two studies examined contingent take-home medication doses during treatment of opiate or cocaine dependence. In the first study, methadone maintenance patients were randomly assigned to one of two 8-week baseline take-home (TH) conditions differing in frequency of clinic visits per week. This was followed by a 12-week contingency management (CM) procedure in which frequent THs resulted from drug-free urines. Participants receiving more frequent THs during baseline had lower illicit drug use during the first 6 weeks of CM. In the second study, fluoxetine (0-, 20-, 40-mg) TH doses were similarly contingent in treatment of cocaine dependence. The 40-mg group used less cocaine during contingency than did other groups. The combination of fluoxetine and environmental contingencies may produce benefit where neither alone is sufficient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)