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1.
Anionic polymerization of ?-caprolactam was initiated with the potassium salt of ?-caprolactam and accelerated with phenyl isocyanate, toluylene diisocyanate, 4,4′-diphenylmethane diisocyanate, some derivatives of these isocyanates (urethanes, ureas, and allophanates), or combinations of phenyl isocyanate with its derivatives at 150°C. The effect of individual structures on the polymerization kinetics and their contribution to the preparation of block copolymers of ?-caprolactam with hydroxy-terminated prepolymers, in-situ functionalized with diisocyanates, are discussed on the basis of a detailed analysis of time functions of polymer yield and degree of polymerization. 相似文献
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Jansa P Becvar R Ambroz D Palecek T Tomcik M Skacelova S Aschermann M Linhart A 《Clinical rheumatology》2012,31(3):557-561
Background
Systemic sclerosis (SSc) is an important cause of pulmonary arterial hypertension (PAH), with an estimated prevalence of 7.85–26.7%. 相似文献6.
Furred subterranean mammals face the problem of dissipating heat to the environment because high humidity and absence of air flow in sealed belowground tunnels constrain heat loss from body by convection and evaporation. In order to detect body areas responsible for heat loss, surface temperatures in two species of African mole-rats were measured at different ambient air temperatures by infrared thermography. Fur characteristics were also evaluated. Thinner pelage of the ventrum, its moderate temperature and large size suggest that ventral side of the body is the main thermal avenue for heat loss in both species. Interspecific differences could be explained by different fur characteristics connected with social thermoregulation. Compared to the social Fukomys mechowii, the solitary Heliophobius argenteocinereus has denser and longer fur on most of its body; its surface temperature was thus lower than in F. mechowii at lowered ambient temperatures. On the other hand, the denser and longer hair cover in H. argenteocinereus impedes heat dissipation at highest ambient temperatures (and probably also during digging activity) resulting in increase of core body temperature. H. argenteocinereus seems to be more sensitive to overheating than F. mechowii. At lower air temperatures, the social species may uses huddling to combat hypothermia. 相似文献
7.
Jancalek R Dubovy P 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2007,179(1):111-119
The treatment of radicular pain is mainly empirical because there are only few experimental studies dealing with morphological
changes during compression radiculopathy. The goal of the study was to investigate changes in the morphology of myelinated
axons during spinal root compression and the influence of decompression in a new rat model. The number of myelinated axons
and their diameter were measured at 1, 2, 5, and 8 weeks during compression of the dorsal spinal root. The same approach was
applied for 1-week compression followed by decompression for 1 or 2 weeks and compression for 5 weeks followed by 3-week decompression.
A decrease in the number of myelinated axons (particularly those of large diameters) occurred after compression for 1 week.
Continued compression for up to 8 weeks resulted in centripetal increase in the number of myelinated axons and the persistence
of a small fraction of large myelinated axons at the site of compression. After that time, a decreased number of axons and
a reduced fraction of large myelinated axons occurred again. Decompression after 1-week compression caused a rapid increase
in the number of both small and large myelinated axons within the spinal root including the site of compression. A small fraction
of regenerated axons was found after 5-week compression followed by 3-week decompression. Finally, we investigated the time
course of the temporary increase in the number of regenerated myelinated axons during dorsal root compression for up to 8 weeks.
The efficacy of decompression was superior when applied one week after compression or after regress of the acute phase of
aseptic inflammation associated with fragility of spinal root. The results of the study verify the need for early surgical
decompression to prevent irreversible damage of the spinal roots. 相似文献
8.
Michal Koínek Radim Halama Frantiek Fojtík Marek Pag
Jií Kr
ek David Krzikalla Radim Kocich Lenka Kun
ick 《Materials》2021,14(1)
The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the “as printed” state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the “as printed” state is also compared with 3D printed machined specimens and specimens produced by conventional methods. “As printed” specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of “as printed” specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed. 相似文献
9.
The exposure of nonsmoking and smoking mothers to environmental tobacco smoke during different gestational phases and fetal growth 总被引:4,自引:0,他引:4
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We studied the impact of maternal exposure to environmental tobacco smoke (ETS) on birth weight (BW), low birth weight (LBW), and intrauterine growth retardation (IUGR) according to self-reported maternal smoking habits in a sample of 6,866 singleton births. We obtained data about parental characteristics and maternal active smoking (AS) and passive smoking at delivery via maternal questionnaires and medical records. We used three categories of smoking habits (nonsmokers and those who smoked 1-10 or >10 cigarettes per day) and defined ETS exposure as greater than or equal to 5 cigarettes per day smoked by others in the mother's presence. We used multiple regression and logistic regression procedures with adjustment for many associated covariates. We observed a significant reduction of the mean BW in infants of AS mothers. This reduction was only marginal for mothers who stopped smoking after recognizing their pregnancy. ETS exposure in 1,797 of 5,507 nonsmoking mothers reduced the mean BW of their infants by 53 g [95% confidence interval (CI), 24-82 g]. ETS exposure also significantly reduced BW in babies of AS mothers by 92 g (CI, 21-113 g) compared with BW of ETS-nonexposed AS mothers. The adjusted odds ratio (AOR) of LBW for ETS-exposed AS mothers was two times the LBW risk of ETS-nonexposed AS mothers(2.02; CI, 1.11-3.67); the AOR of ETS-exposed nonsmoking mothers was 1.51 (CI, 1.02-2.26). The AOR of IUGR for this group did not differ from unity (1.08; CI, 0.82-1.43). However, ETS exposure increased the AOR of IUGR for AS mothers from 1.64 (CI, 1.06-2.53) to 2.13 (CI, 1.70-2.67). ETS exposure reduced the BW of infants of nonsmoking mothers and contributed to additional BW reduction in infants of AS mothers. ETS exposure increased the risk of LBW but not that of IUGR in babies of nonsmoking mothers. 相似文献
10.
A randomised controlled trial of intravenous immunoglobulin in IgM paraprotein associated demyelinating neuropathy 总被引:3,自引:0,他引:3
Comi G Roveri L Swan A Willison H Bojar M Illa I Karageorgiou C Nobile-Orazio E van den Bergh P Swan T Hughes R Aubry J Baumann N Hadden R Lunn M Knapp M Léger JM Bouche P Mazanec R Meucci N van der Meché F Toyka K;Inflammatory Neuropathy Cause Treatment Group 《Journal of neurology》2002,249(10):1370-1377
This multicentre randomised double blind crossover trial tested the short term efficacy of intravenous immunoglobulin (IVIg)
2.0 g/kg given over 24 or 48 hours in patients with paraproteinaemic demyelinating neuropathy (PDN). Twenty-two patients were
randomised and completed the trial. After 2 weeks, the overall disability grade decreased during both IVIg treatment and placebo
but neither change was significant nor was the mean difference between the treatment effects. After 4 weeks the overall disability
decreased by a mean of 0.55 [0.67] grades during the IVIg period (p = 0.001) while it was substantially unmodified during
the placebo period. The mean difference between the treatment effects was significant (p = 0.05). Overall during the IVIg
period 10 patients improved and 11 were stable and one got worse. During the placebo period 4 patients improved, 4 deteriorated
and 14 were stable. Many secondary outcome measures, including Rankin scale, time to walk 10 metres, grip strength, sensory
symptoms score were significantly better during IVIg treatment. Two serious adverse events occurred during the trial, both
during placebo treatment. In conclusion the trial showed some short-term benefit of IVIg in about half of the patients confirming
previous observation.
Received: 6 August 2001, Received in revised form: 6 March 2002, Accepted: 12 March 2002
RID="*"
ID="*"The other members of the INCAT group are Jacques Aubry PhD, Institut de Biologie, INSERM Unit 463, 9 Quai Moncousu,
44 035 Nantes, France; Nicole Baumann MD, InSERM Unit 495, Salpetriere Hospital, 75 651 Paris, Cedex 13 France; Robert Hadden
PhD, Michael Lunn, MD, Department of Neuroimmunology, Guy's, King's and St. Thomas' School of Medicine, Guy's Hospital, London
SE1 9 UL, UK; Martin Knapp Phd, Personal Social Services Research Unit, London School of Economics and Political Science,
Houghton Street, London WC2A 1AE, UK; Jean-Marc Léger MD, Pierre Bouche MD, Service d'Eplorations Functionelles de la Salpetriere,
47 Boulevard de l'Hospital, 75 651 Paris, Cedex 13, France; Radim Mazanec CSc, Charles University, 2nd Medical School, University Hospital, V uvalu 84, Prague 5, Czech Republic; Nicoletta Meucci MD, Institute of Clinical Neurology,
University of Milan, Ospedale Maggior-Policlinico, via Sforza, 20 122 Milan, Italy; Frans van der Meché PhD, Department of
Neurology, Erasmus Medical Center Rotterdam, dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands; and Klaus Toyka PhD,
Universitat Würzburg, Josef-Schneider Strasse 2, 97 080 Würzburg, Germany
Correspondence to Giancarlo Comi, MD 相似文献