534 research outputs found
Thermal and dynamic mechanical properties of blends of bitumen with metallocene catalyzed polyolefins
No full textA high penetration grade bitumen has been blended with up to 50 wt% of two different grades of metallocene catalyzed linear low density polyethylene (m-LLDPE) in order to investigate the potential of these and similar copolymers as a substitute for styrene butadiene styrene triblock copolymers in polymer-modified bitumens (PMB). A continuous polymer-rich phase was observed at m-LLDPE contents as low as 5-10 wt%, along with a significant decrease in the effective glass transition temperature of the PMBs with increasing polymer concentration, suggesting benefits for low temperature flexibility. The m-LLDPE-based PMBs also showed relatively low dynamic shear viscosities up to high polymer contents in the range of temperature and shear rate corresponding to typical PMB processing conditions. However, the presence of bitumen in the m-LLDPE-rich phase led to a significant reduction in the melting points of the m-LLDPE, and softening of the PMBs at temperatures as low as 40-50 degrees C, depending on the composition and the melting point of the pure polymer. PMBs based on the m-LLDPE with the higher melting point remained fully elastic in this temperature range, but at the expense of increased crystallinity and a higher glass transition temperature, which limit improvements in low temperature flexibility. On the other hand, the potentially broad composition and property windows associated with m-LLDPEs suggest considerable scope for the fine tuning of PMB properties by using combinations of different m-LLDPEs and/or other polyolefins as a means to optimize performance.LTC[Spadaro, Chiara; Plummer, Christopher J. G.; Manson, Jan-Anders E.] Ecole Polytech Fed Lausanne, Lab Technol Composites & Polymeres LTC, Stn 12, CH-1015 Lausanne, Switzerland. Plummer, CJG (reprint author), Ecole Polytech Fed Lausanne, Lab Technol Composites & Polymeres LTC, Stn 12, CH-1015 Lausanne, Switzerland [email protected] Document Delivery No.: 824CSCited Reference Count: 39Spadaro, Chiara Plummer, Christopher J. G. Manson, Jan-Anders E.Swiss Innovation Promotion Association (KTI/CTI)The authors wish to acknowledge the financial support of the Swiss Innovation Promotion Association (KTI/CTI).SpringerNew yorkNational Licence
Brain-Derived Neurotrophic Factor-Induced Gene Expression Reveals Novel Actions of VGF in Hippocampal Synaptic Plasticity
No full textSynaptic strengthening induced by brain-derived neurotrophic factor (BDNF) is associated with learning and is coupled to transcriptional activation. However, identification of the spectrum of genes associated with BDNF-induced synaptic plasticity and the correlation of expression with learning paradigms in vivo has not yet been studied. Transcriptional analysis of BDNF-induced synaptic strengthening in cultured hippocampal neurons revealed increased expression of the immediate early genes (IEGs), c-fos, early growth response gene 1 (EGR1), activity-regulated cytoskeletal-associated protein (Arc) at 20 min, and the secreted peptide VGF (non-acronymic) protein precursor at 3 hr. The induced genes served as prototypes to decipher mechanisms of both BDNF-induced transcription and plasticity. BDNF-mediated gene expression was tyrosine kinase B and mitogen-activated protein kinase-dependent, as demonstrated by pharmacological studies. Single-cell transcriptional analysis of Arc after whole-cell patch-clamp recordings indicated that increased gene expression correlated with enhancement of synaptic transmission by BDNF. Increased expression in vitro predicted elevations in vivo: VGF and the IEGs increased after trace eyeblink conditioning, a hippocampal-dependent learning paradigm. VGF protein was also upregulated by BDNF treatment and was expressed in a punctate manner in dissociated hippocampal neurons. Collectively, these findings suggested that the VGF neuropeptides may regulate synaptic function. We found a novel function for VGF by applying VGF peptides to neurons. C-terminal VGF peptides acutely increased synaptic charge in a dose-dependent manner, whereas N-terminal peptide had no effect. These observations indicate that gene profiling in vitro can reveal new mechanisms of synaptic strengthening associated with learning and memory.Peer reviewe
Highly filled Polystyrene-laponite nanocomposites prepared by emulsion polymerization
No full textPolystyrene-based nanocomposite films containing up to 20 wt% laponite clay have been prepared by emulsion polymerization. Significant increases in the storage and tensile moduli were observed in both the glassy and rubbery state on laponite addition. However, whereas in the glassy state these increases were correlated with the extent of exfoliation of the laponite, in the rubbery state they were more dependent on the overall laponite content. These results are discussed in terms of the observed morphologies and micromechanical models for the reinforcing effect of rigid nano-sized filler particles.LTC[Ruggerone, Riccardo Plummer, Christopher J. G. Manson, Jan-Anders E.] Ecole Polytech Fed Lausanne, LTC, Stn 12, CH-1015 Lausanne, Switzerland. [Herrera, Norma Negrete Bourgeat-Lami, Elodie] CNRS CPE UCBL, UMR 5265, LCPP C2P2, F-69616 Villeurbanne, France. Manson, JAE, Ecole Polytech Fed Lausanne, LTC, Stn 12, CH-1015 Lausanne, Switzerland. [email protected] Document Delivery No.: 419PYCited Reference Count: 55Ruggerone, Riccardo Plummer, Christopher J. G. Herrera, Norma Negrete Bourgeat-Lami, Elodie Manson, Jan-Anders E.European Framework 6 Project NAPOLEON ; Centre Interdisciplinaire de Microscopie Electronique (CIME) of the EPFLThis work was supported by the European Framework 6 Project NAPOLEON and technical support was provided the Centre Interdisciplinaire de Microscopie Electronique (CIME) of the EPFL.PERGAMON-ELSEVIER SCIENCE LTDOXFOR
Usanus stonei DeLong 1947
No full textUsanus stonei DeLong, 1947 Usanus stonei DeLong, 1947: 110 Devolana hemicycla DeLong, 1967: 23, comb. et syn. nov. Type material examined. HOLOTYPE ♂: labeled as “ Devolana hemicycla ”, MEXICO: Guerrero, Iguala, X–25–1941 / DeLong, Good, Caldwell and Plummer Colls. / E–103 / D. M. DeLong Collection / (OSUC 0209432); HOLOTYPE ♂: labeled as “ Usanus stonei ”, MEXICO: Guerrero, Iguala, X–22–1941 / D. M. DeLong Collection, DeLong, Good, Caldwell and Plummer Colls. / (OSUC 169297); PARATYPE ♂: labeled as “ Usanus stonei ”, MEXICO: Guerrero, Iguala, X–25–1941 / D. M. DeLong Collection / D. M. DeLong Coll. / (OSUC 356667).Published as part of Pinedo-Escatel, J. Adilson & Dietrich, Christopher H., 2020, Nomenclatural changes and two new species in the leafhopper genus Usanus DeLong (Hemiptera: Cicadellidae) with notes on conservation status, pp. 567-576 in Zootaxa 4822 (4) on page 572, DOI: 10.11646/zootaxa.4822.4.6, http://zenodo.org/record/440186
Cardiotoxicity of anthracycline agents for the treatment of cancer: systematic review and meta-analysis of randomised controlled trials
No full textBackground: We conducted a systematic review and meta-analysis to clarify the risk of early and late cardiotoxicity of anthracycline agents in patients treated for breast or ovarian cancer, lymphoma, myeloma or sarcoma.Methods: Randomized controlled trials were sought using comprehensive searches of electronic databases in June 2008. Reference lists of retrieved articles were also scanned for additional articles. Outcomes investigated were early or late clinical and sub-clinical cardiotoxicity. Trial quality was assessed, and data were pooled through meta-analysis where appropriate.Results: Fifty-five published RCTs were included; the majority were on women with advanced breast cancer. A significantly greater risk of clinical cardiotoxicity was found with anthracycline compared with non-anthracycline regimens (OR 5.43 95% confidence interval: 2.34, 12.62), anthracycline versus mitoxantrone (OR 2.88 95% confidence interval: 1.29, 6.44), and bolus versus continuous anthracycline infusions (OR 4.13 95% confidence interval: 1.75, 9.72). Risk of clinical cardiotoxicity was significantly lower with epirubicin versus doxorubicin (OR 0.39 95% confidence interval: 0.20, 0.78), liposomal versus non-liposomal doxorubicin (OR 0.18 95% confidence interval: 0.08, 0.38) and with a concomitant cardioprotective agent (OR 0.21 95% confidence interval: 0.13, 0.33). No statistical heterogeneity was found for these pooled analyses. A similar pattern of results were found for subclinical cardiotoxicity; with risk significantly greater with anthracycline containing regimens and bolus administration; and significantly lower risk with epirubicin, liposomal doxorubicin versus doxorubicin but not epirubicin, and with concomitant use of a cardioprotective agent. Low to moderate statistical heterogeneity was found for two of the five pooled analyses, perhaps due to the different criteria used for reduction in Left Ventricular Ejection Fraction. Meta-analyses of any cardiotoxicity (clinical and subclinical) showed moderate to high statistical heterogeneity for four of five pooled analyses; criteria for any cardiotoxic event differed between studies. Nonetheless the pattern of results was similar to those for clinical or subclinical cardiotoxicity described above.Conclusions: Evidence is not sufficiently robust to support clear evidence-based recommendations on different anthracycline treatment regimens, or for routine use of cardiac protective agents or liposomal formulations. There is a need to improve cardiac monitoring in oncology trials.<br/
Molecular dynamics simulations of the intrinsically disordered protein amelogenin
No full textAmelogenin refers to a class of intrinsically disordered proteins that are the major constituents of enamel matrix derivative (EMD), an extract of porcine fetal teeth used in regenerative periodontal therapy. Modifications in molecular conformation induced by external stresses, such as changes in temperature or pH, are known to reduce the effectiveness of EMD. However, detailed descriptions of the conformational behavior of native amelogenin are lacking in the open literature. In the present work, a molecular model for the secondary and tertiary structure of the full-length major porcine amelogenin P173 was constructed from its primary sequence by replica exchange molecular dynamics (REMD) simulations. The REMD results for isolated amelogenin molecules at different temperatures were shown to be consistent with the available spectroscopic data. They therefore represent an important first step toward the simulation of the intra- and intermolecular interactions that mediate self-organization in amelogenin and its behavior in the presence of other EMD components under conditions representative of its therapeutic application
Hybrid glass mat reinforced polypropylene-montmorillonite nanocomposites
No full textAlthough addition of montmorillonite (MMT) clay to isotactic polypropylene (iPP) results in large increases in the melt viscosity at low shear rates, satisfactory impregnation of glass mats is obtained with iPP/MMT under conditions typical of industrial processing, and the MMT is well dispersed throughout the resulting composites. However, the MMT is also shown to retard relaxation of the glass mat, leading to non-uniform through-thickness glass fiber distributions. Thus, depending on the initial lay-up and hence on the initial surface fiber concentration, the bending modulus of the consolidated specimens may either increase or decrease with increasing matrix MMT content, whereas the tensile modulus remains consistent with the predictions of micromechanical models based on the assumption of a uniform glass fiber distribution. The presence of matrix-rich layers at surfaces of specimens containing MMT is also shown to promote crack initiation and induce premature failure in flexural tests.LT
Predicting walking METs and energy expenditure from speed or accelerometry
No full textPURPOSE: a) Compare the predictive potential of speed and CSA(hip) (Computer Science Applications accelerometer positioned on the hip) for level terrain walking METs (1 MET = VO2 of 3.5 mL.kg(-1).min(-1)) and energy expenditure (kcal.min(-1)); b) cross-validate previously published CSA(hip)- and speed-based MET and energy expenditure prediction equations; c) measure self-paced walking speed, exercise intensity (METs) and energy expenditure in the middle aged population. METHODS: Seventy-two 35- to 45-yr-old volunteers walked around a level, paved quadrangle at what they perceived to be a moderate pace. Oxygen consumption was measured using the criterion Douglas bag technique. Speed, CSA(hip), heart rate, and Borg rating of perceived exertion were also monitored. RESULTS: Speed explained 10% more variance of walking METs than CSA(hip). Speed and mass explained 8% more variance of walking energy expenditure (kcal.min) than CSA(hip) and mass. The best previously published regression equations predict our walking METs and energy expenditures within 95% prediction limits of +/- 0.7 METs and +/- 1.0 kcal.min(-1), respectively. Women paced themselves at a significantly higher mean speed (5.5 km.h(-1)) and intensity (4.1 METs) than their male counterparts (5.2 km.h(-1) and 3.8 METs). Both genders expended approximately 0.75 kcal.kg(-1) for every kilometer of level terrain walked. CONCLUSION: Speed-based MET and energy expenditure predictions during level terrain walking were more accurate than those utilizing CSA(hip).Brooks, Anthony G.; Gunn, Simon M.; Withers, Robert T.; Gore, Christopher J. and Plummer, John L.http://www.ncbi.nlm.nih.gov/pubmed/1601514
The absorption spectrum of deutereted cyanoacethylene between 180 and has been recorded in W\"{u}ppertal with a resolution of .The following transitions and their associated hot bands have been observed: and . From these spectra we have obtained with an accuracy in the range of the vibrational energies of most states of DCCCN below . These results combined with the Stark transitions and the microwave yields the determination of any and anharmonicity parameters with to 7. The observation of the crossing of with at and with at confirms the anharmonic interactions scheme of Plummer
No full textAuthor Institution: Universite Catholique de Louvain, Molecular Spectroscopy Laboratory 2 chemin du cyclotron; FB9 Anorgan. Chemic, Bergische Univ. - Gesamthochschule W\""{u}ppertal B. Coveliers. W.K. Ahmed, A. Fayt and A.G. Maki, submitted to the J. Mol. Spectrosc. G.M. Plummer. D. Mauer, and K.M.T. Yamada, J. Mol. Spectrosc. 130, 407-418 (1988)
Measurement and prediction of METs during household activities in 35- to 45-year-old females
No full textThis study determined whether four self-paced household tasks, conducted in the subjects homes and a standardised laboratory environment, were performed at a moderate intensity [3–6 metabolic equivalents (METs)] in a representative sample of thirty-six 35- to 45-year-old females. Energy expenditure was also predicted via indirect methods. Self-paced energy expenditure during sweeping, window cleaning, vacuuming and mowing was measured using the Douglas bag technique. Heart rate, respiratory frequency, Computer Science Applications (CSA) movement counts (hip and wrist), Borg rating of perceived exertion and Quetelets index were also recorded as potential predictors of energy expenditure. While the four activities were performed at mean intensities 3.0 METs in both the home and laboratory, all comparisons between these two environments were statistically significant (P<0.001). The 95% confidence intervals (CIs) for the home and laboratory prediction equations were ±1.1 METs and ±1.0 MET, respectively. These data suggest that the aforementioned household chores can contribute to the 30 min·day–1 of moderate-intensity activity required to confer health benefits. However, the substantial between-subject variability in energy expenditure resulted in some persons performing these tasks at a light intensity (<3.0 METs). The significant MET differences between the home and laboratory emphasise the effects of environment and terrain and the mental approach to a task on self-paced energy expenditure. Considering the means for the five activities ranged from 3.1 METs to 6.0 METs, the 95% CIs for the regression equations lack predictive precision.Anthony G. Brooks, Robert T. Withers, Christopher J. Gore, Andrew J. Vogler, John Plummer and John Cormac
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