Be careful when using X-ray exposure analysis for polymers

Briskman, B. A.

doi:10.1016/j.nimb.2007.08.059

Cited by 7 publications

(4 citation statements)

References 17 publications

(23 reference statements)

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“…Thermal analysis and crystalline test, presented in Figure 8, shows that raw PTFE has higher melting enthalpy and a sharp crystallization peak. After the melting–cooling cycle, the melting point of PTFE becomes lower; the peak in XRD is not sharp anymore, and a shoulder peak appears around 15° which is attributed to amorphous region 24, 25. This is because when the temperature is above the melting point of PTFE, the polymer chain will become amorphous and get entangled with each other.…”

Section: Resultsmentioning

confidence: 99%

The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy

Coley¹,

Rayavarapu²,

Pandey³

et al. 2012

Arthritis & Rheumatism

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OBJECTIVE It is generally believed that muscle weakness in patients with polymyositis and dermatomyositis is due to autoimmune and inflammatory processes. However, it has been observed that there is a poor correlation between the suppression of inflammation and a recovery of muscle function in patients. We have therefore hypothesized that non-immune mechanisms also contribute to muscle weakness. In particular, it has been suggested that an acquired deficiency of AMP deaminase (AMPD1) may be responsible for muscle weakness in myositis. METHODS We have used comprehensive functional, behavioral, histological, molecular, enzymatic and metabolic assessments before and after the onset of inflammation in MHC class I mouse model of autoimmune inflammatory myositis. RESULTS We found that muscle weakness and metabolic disturbances were detectable in the mice prior to the appearance of infiltrating mononuclear cells. Force contraction analysis of muscle function revealed that weakness was correlated with AMDP1 expression and was myositis-specific. We also demonstrated that decreasing AMPD1 expression results in decreased muscle strength in healthy mice. Fiber typing suggested that fast-twitch muscles are converted to slow-twitch muscles as myositis progresses, and microarray results indicated that AMPD1 and other purine nucleotide pathway genes are suppressed, along with genes essential to glycolysis. CONCLUSION These data suggest that an AMPD1 deficiency is acquired prior to overt muscle inflammation and is responsible, at least in part, for the muscle weakness that occurs in the mouse model of myositis. AMPD1 is therefore a potential therapeutic target in myositis.

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Section: Resultsmentioning

confidence: 99%

The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy

Coley¹,

Rayavarapu²,

Pandey³

et al. 2012

Arthritis & Rheumatism

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“…Application of this method is typically expensive, time consuming and destructive (Vailaya et al, 2001; Saeki et al, 2003). X‐ray scattering methods are a family of non‐destructive methods based on the scattered intensity of a beam hitting a sample and providing information about the average structure and composition (Brown et al, 1973; Polizzi et al, 1991; Albano et al, 2003; Pantani et al, 2005; Pelsoci, 2007; Briskman, 2007). As these methods depend on the incident and scattering angles, as well as the polarization and wavelengths of the beams, they are not easily adapted to 2D surface scans.…”

Section: Introductionmentioning

confidence: 99%

On‐line prediction of crystallinity spatial distribution across polymer films using NIR spectral imaging and chemometrics methods

2008

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A rapid and non-intrusive on-line NIR imaging sensor is developed for monitoring spatio-temporal crystallinity variations across the surface of polymer films. A multivariate image analysis and regression (MIA/MIR) approach is proposed and compared with standard NIR calibration techniques using averaged spectra or second order derivatives combined with PLS regression. Predictions of both the local and global crystallinity variations of HDPE, LDPE, and PP polymer samples were obtained with each approach. Our results show that small variations in crystallinity introduced by changes in cooling rates can be predicted within experimental errors. Crystallinity spatial distributions were also validated and found consistent with processing conditions. Un capteur d'imagerie en proche infrarouge (NIR) rapide et non intrusif est mis au point pour faire le suivi des variations de cristallinité spatiotemporelleà la surface des films de polymères. Une approche par régression et analyse d'images multivariées (MIA/MIR) est proposée et comparée aux techniques de calibration NIR utilisant des spectres moyens ou des dérivées du second ordre combinésà la régression PLS. Des prédictions des variations de cristallinité locales et globales d'échantillons de polymères HDPE, LDPE et PP sont obtenues avec chacune des approches. Nos résultats montrent que de faibles variations dans la cristallinité introduites par des changements dans les vitesses de refroidissement peuventêtre préditesà l'intérieur des erreurs expérimentales. Les distributions spatiales de cristallinité sontégalement validées et s'avèrent cohérentes avec les conditions de traitement.

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“…In the past few decades, a great interest has been focused on radiation of PTFE. Radiation effect of PTFE has been widely investigated [2][3][4][5][6][7][8][9]. It was found that the wear resistance of bulk PTFE sliding against such smooth counter surfaces can also be increased through gamma [10] irradiation, approaching the wear resistance of materials possessing hard fillers while not being abrasive.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Friction and Wear Properties of PTFE Coatings under Vacuum Conditions before and after Gamma Irradiation

Yuan

Yang

et al. 2011

AMR

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The friction and wear properties of Polytetrafluoroethylene (PTFE) coatings before and after gamma irradiation were studied under vacuum conditions. Experimental results indicated that the friction and wear properties of PTFE coatings were improved by gamma irradiation. Results showed that the wear process of PTFE coatings before and after gamma irradiation consists of three stages. The steps for the irradiated PTFE are slightly longer than that for the non-irradiated samples. The friction coefficient of irradiated PTFE coatings reduces slightly compared to that of the non-irradiated samples. The friction coefficients of the PTFE coatings before and after gamma irradiation first increase with the increase of sliding velocity and then decrease with the increase of sliding velocity, and The friction coefficient of PTFE coatings before and after gamma irradiation decreases with the increase of load. The wear of irradiated PTFE coatings is slightly lower than that of non-irradiated PTFE coatings. The wear of PTFE coatings before and after gamma irradiation first decreases with the increase of sliding speed and then increases as the sliding speed increases. The wear of PTFE coatings first decreases with the increase of load and then increases with the increase of load. Scanning electron microscope (SEM) was utilized to investigate the worn surfaces.

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Be careful when using X-ray exposure analysis for polymers

Cited by 7 publications

References 17 publications

The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy

The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy

On‐line prediction of crystallinity spatial distribution across polymer films using NIR spectral imaging and chemometrics methods

Comparison of the Friction and Wear Properties of PTFE Coatings under Vacuum Conditions before and after Gamma Irradiation

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