多层帘式涂布和一种新型压光技术

帘式涂布是一种低冲击预计量涂布方式,可用于纸和纸板的涂布、帘式涂布技术所产生的涂层为仿形涂层,因而能提供良好的纤维覆盖。在多层帘式涂布中,可以同时进行多层涂布。与单层帘式涂布相比,多层帘式涂布具有许多优点：投资成本更低、设计不同涂层性质更具灵活性、具有更大的涂布操作空间及涂层更薄等,     

Diffusion and perfusion MR imaging in acute ischemic stroke: a comparison to SPECT

Diffusion (DWI) and perfusion (PWI) magnetic resonance imaging are relatively new methods of clinical imaging that probably can detect infarcted (DWI) and hypoperfused but still salvageable tissue (PWI) in acute human stroke. Forty-six acute stroke patients were imaged within 24 h of ictus, on the second day and after a week. SPECT was also performed on 23 patients in the acute phase (first or second day). On the first day, mean volume of hypoperfused tissue was significantly greater (P<0.001) than the infarcted tissue. The initial hypoperfusion volume correlated significantly with the final infarct size (P<0.001). The initial perfusion-diffusion mismatch correlated significantly with the infarct growth (P< or =0.001). The hypoperfusion volumes measured from PWI and SPECT correlated significantly (P<0.001). In conclusion, combined DWI and PWI is a powerful tool in evaluating the hemodynamics of acute ischemic stroke and can predict the infarct growth during 1 week.     

MR imaging in pelvic inflammatory disease: comparison with laparoscopy and US

PURPOSE: To assess the value of magnetic resonance (MR) imaging in the diagnosis of pelvic inflammatory disease (PID) and to compare MR imaging with transvaginal ultrasonography (US) and laparoscopy. MATERIALS AND METHODS: Thirty consecutive patients hospitalized because they were clinically suspected of having PID underwent transvaginal US and T1-weighted spin-echo, T2-weighted turbo spin-echo, and inversion-recovery MR imaging at 1.5 T. All patients underwent laparoscopy after MR imaging. RESULTS: PID was laparoscopically proved in 21 (70%) patients. The MR imaging diagnosis agreed with that obtained with laparoscopy in 20 (95%) of the 21 patients with PID. The imaging findings for PID were as follows: fluid-filled tube, pyosalpinx, tubo-ovarian abscess, or polycystic-like ovaries and free pelvic fluid. Findings at transvaginal US agreed with those at laparoscopy in 17 (81%) of the 21 patients with PID. The sensitivity of MR imaging in the diagnosis of PID was 95%, the specificity was 89%, and the overall accuracy was 93%. For transvaginal US, the corresponding values were 81%, 78%, and 80%. CONCLUSION: MR imaging is more accurate than transvaginal US in the diagnosis of PID and provides information about the differential diagnosis of PID. MR imaging may reduce the need for diagnostic laparoscopy.     

Effects of interstimulus interval on somatosensory evoked magnetic fields (SEFs): a hypothesis concerning SEF generation at the primary sensorimotor cortex

Cerebral responses evoked by peripheral stimuli are known to depend critically on the interstimulus interval (ISI). Here we report on the effects of ISI on somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation, obtained in 9 healthy adults with ISIs of 0.15 0.3, 1,3 and 5 s. At the contralateral (left) primary sensorimotor cortex (SMI), the first cortical response, N20m, was stable between the ISIs 0.3 and 5 s, but slightly attenuated at the shortest ISI of 0.15 s. In contrast, the P35m and P60m deflections were very sensitive to changes of the ISI, declining steadily with shortening of the ISI throughout the entire range. These deflections were frequently undetectable at the shortest ISI of 0.15 s. Concomitant with the reductions of P35m and P60m, an N45m deflection was enhanced toward the short ISIs. Responses from second somatosensory cortex (SII) and posterior parietal cortex (PPC) were seen only with ISIs of 1 s or greater, being strongest at the 5 s ISI. Based on known effects of the ISI on intracellular evoked potentials, we present the following tentative model for the generation mechanism of the SMI response: N20m represents early excitatory postsynaptic potentials (EPSPs), P35m early inhibitory postsynaptic potentials (IPSPs), N45m secondary EPSPs and P60m late IPSPs in pyramidal neurones of area 3b. For practical purposes, SEFs from SMI can be obtained with short ISIs, while responses from SII and PPC require an ISI of at least 1 s.     

Distribution of cortical activation during visuospatial n-back tasks as revealed by functional magnetic resonance imaging

Ten bacterial strains were isolated from seven contaminated soils by enrichment with phenanthrene as the sole carbon source. These isolates and another phenanthrene-degrading strain were examined for various characteristics related to phenanthrene degradation and their ability to metabolize 12 other polycyclic aromatic hydrocarbons (PAH), ranging in size from two to five rings, after growth in the presence of phenanthrene. Fatty acid methyl ester analysis indicated that at least five genera (Agrobacterium, Bacillus, Burkholderia, Pseudomonas, and Sphingomonas) and at least three species of Pseudomonas were represented in this collection. All of the strains oxidized phenanthrene according to Michaelis-Menten kinetics, with half-saturation coefficients well below the aqueous solubility of phenanthrene in all cases. All but one of the strains oxidized 1-hydroxy-2-naphthoate following growth on phenanthrene, and all oxidized at least one downstream intermediate from either or both of the known phenanthrene degradation pathways. All of the isolates could metabolize (oxidize, mineralize, or remove from solution) a broad range of PAH, although the exact range and extent of metabolism for a given substrate were unique to the particular isolate. Benz[a]anthracene, chrysene, and benzo[a]pyrene were each mineralized by eight of the strains, while pyrene was not mineralized by any. Pyrene was, however, removed from solution by all of the isolates, and the presence of at least one significant metabolite from pyrene was observed by radiochromatography for the five strains in which such metabolites were sought. Our results support earlier indications that the mineralization of pyrene by bacteria may require unique metabolic capabilities that do not appear to overlap with the determinants for mineralization of phenanthrene or other high molecular weight PAH.     

Variable agreement between visual rating scales for white matter hyperintensities on MRI. Comparison of 13 rating scales in a poststroke cohort

BACKGROUND AND PURPOSE: Previous reports on the frequency, extent, and clinical correlates of white matter hyperintensities (WMHIs) have been contradictory. The purpose of this study was to test whether part of this variation could be explained by the different properties of the visual WMHI rating scales used. METHODS: The periventricular (PVHIs) and deep white matter (DWMHIs) hyperintensities of 395 poststroke patients were systematically analyzed and transformed to correspond to 13 different rating scales. The scales were compared with the use of Goodman-Kruskal measures of association. The relative frequencies, means, and medians of PVHI and DWMHI grades as well as Spearman rank correlations between WMHI grade and hypertension were calculated. RESULTS: At best more than 80% of the patients received an equivalent WMHI grade by different scales, but at worst the corresponding values were only 0.4% for PVHI and 18% for DWMHI. At best different scales categorized patients similarly in regard to WMHI grade, but at worst the corresponding values were 8% for PVHI and 57% for DWMHI ratings. The distribution of WMHI grades also varied, and when the effect of age on WMHI was assessed, some of the scales had a ceiling effect and some had a floor effect. Only 1 of the 7 PVHI, 5 of the 9 DWMHI, and 1 of the 3 combined rating scales showed a significant correlation with arterial hypertension, a putative risk factor for WMHIs. CONCLUSIONS: Some of the inconsistencies in previous studies of WMHIs are due to differences in visual rating scales. Our findings may warrant international debate regarding harmonization of WMHI ratings.     

Contextual clustering for analysis of functional MRI data

We present a contextual clustering procedure for statistical parametric maps (SPM) calculated from time varying three-dimensional images. The algorithm can be used for the detection of neural activations from functional magnetic resonance images (fMRI). An important characteristic of SPM is that the intensity distribution of background (nonactive area) is known whereas the distributions of activation areas are not. The developed contextual clustering algorithm divides an SPM into background and activation areas so that the probability of detecting false activations by chance is controlled, i.e., hypothesis testing is performed. Unlike the much used voxel-by-voxel testing, neighborhood information is utilized, an important difference. This is achieved by using a Markov random field prior and iterated conditional modes (ICM) algorithm. However, unlike in the conventional use of ICM algorithm, the classification is based only on the distribution of background. The results from our simulations and human fMRI experiments using visual stimulation demonstrate that a better sensitivity is achieved with a given specificity in comparison to the voxel-by-voxel thresholding technique. The algorithm is computationally efficient and can be used to detect and delineate objects from a noisy background in other applications.