Laser-Based Mass Spectrometric Assessment of Asphaltene Molecular Weight, Molecular Architecture, and Nanoaggregate Number

2015 ◽  
Vol 29 (5) ◽  
pp. 2833-2842 ◽  
Author(s):  
Andrew E. Pomerantz ◽  
Qinghao Wu ◽  
Oliver C. Mullins ◽  
Richard N. Zare
Keyword(s):  
Molecular Weight ◽  
Mass Spectrometric ◽  
Molecular Architecture

Role of molecular architecture in interfacial self-adhesion of polyethylene films

2017 ◽  
Vol 33 (3) ◽  
pp. 235-261 ◽  
Author(s):  
Zahra Najarzadeh ◽  
Abdellah Ajji
Keyword(s):  
Molecular Weight ◽  
Adhesion Strength ◽  
Film Surface ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Molecular Architecture ◽  
Melt Temperature ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

The influence of molecular architecture on interfacial self-adhesion above polyethylene film melt temperature was examined in this study. The investigated molecular structures include molecular weight (Mw), molecular weight distribution, long chain branch amount and distribution and short chain branch among and along polyethylene chains. The long chain branches concentration was quantified using gel permeation chromatography and short branches concentration using nuclear magnetic resonance techniques. The adhesion strength was measured immediately after melt bonding using a T-Peel test. The results showed that increasing Mw resulted in higher adhesion strength in linear metallocene ethylene α-olefins. Low long chain branch concentrations hinder reptation motion and diffusion, and result in lower adhesion strength. Low density polyethylene with highly branched chains yielded very low self-adhesion. A drastic difference in adhesion strength between metallocene and conventional linear low density polyethylene is attributed to homogeneity versus heterogeneity of composition distribution. The low interfacial self-adhesion in conventional polyethylene was concluded to be due to enrichment of highly branched low molecular weight chains at the film surface. These segregated chains at the interface diffuse before the high molecular weight chains located in the bulk.

scholarly journals Integrated microfluidic aptasensor for mass spectrometric detection of vasopressin in human plasma ultrafiltrate

2016 ◽  
Vol 8 (26) ◽  
pp. 5190-5196 ◽  
Author(s):  
J. Yang ◽  
J. Zhu ◽  
R. Pei ◽  
J. A. Oliver ◽  
D. W. Landry ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Human Plasma ◽  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Low Molecular Weight ◽  
Plasma Ultrafiltrate

We present a microfluidic aptamer-based biosensor for detection of low-molecular-weight biomarkers in patient samples.

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