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10.4194/afs14 ◽  
2021 ◽  
Vol 01 (01) ◽  
Author(s):  
Wattan Temdee ◽  
Soottawat Benjakul ◽  
Vijay Kumar Reddy Surasani ◽  
Avtar Singh

The effect of ethanolic extracts of kiam wood (EKW) or cashew bark (ECB) and commercial phenolic compounds oxidized under alkaline condition (pH 9) on gel properties of gelatin extracted from cuttlefish skin was investigated. All the oxidized compounds increased gel strength (GS) of gelatin, in which the highest value was noticed for gels containing oxidized catechin (CH-G) and gallic acid (GA-G) (P<0.05). Among the ethanolic extracts, the gel added with EKW (EKW-G) had higher GS than that containing ECB gel (ECB-G) (P<0.05). Both extracts yielded gels with similar GS to those added with oxidized ferulic and tannic acids (P>0.05). Lightness and free amino group content of gels were decreased with the addition of oxidized compounds, regardless of their types. Gels added with oxidized compounds showed lower solubility and amino group content as compared to the control, indicating the formation of nondisulphide covalent bonds in the gel matrix. The treated samples showed a gel network with thicker strands and larger voids, compared with the control gel. Overall, oxidized EKW extract had a similar impact on the gel properties of gelatin to the oxidized phenolic compounds, especially catechin and gallic acids.


Cellulose ◽  
2021 ◽  
Author(s):  
Ning Yan ◽  
Xin-Sheng Chai ◽  
Troy Runge

AbstractThis study describes a multi-wavelength spectroscopic method for the determination of carboxyl group content of nanocellulose. Methylene blue (MB) was used as a color indicator, which can bind to the carboxyl groups in nanocellulose to form a R-COOMB complex with a binding ratio of 1:1, although the spectrums of MB and R-COOMB at 500–750 nm are overlapped, and solid impurities could cause spectral interference. To solve these issues, a multi-wavelength spectroscopic measurement on a MB and nanocellulose mixture solution technique and mathematical model were developed, allowing the content of carboxyl groups in nanocellulose to be quantified. The results showed that the method has good measurement precision and accuracy as compared with those measured by a reference method. The method is simple and requires only a small sample size for testing and thus makes it suitable for nanocellulose related research and applications.


2021 ◽  
Author(s):  
Magdalena Wojcieszak ◽  
Andreu Casas ◽  
Xudong Yu ◽  
Jonathan Nagler ◽  
Joshua A Tucker

Analyzing four years of data from a random sample of about 1.5 million Twitter users (and about 180,000 politically engaged users), we revisit the debate regarding the extent to which social media users live in political ``echo chambers'' with two new analytic approaches. First, we focus on the sharing of content from political elites, arguably the most influential and politically active actors, and estimate the extent to which ordinary users share messages from politicians, pundits, and news media of the same versus opposing ideology. Second, we examine the extent to which this sharing is annotated by users before it is shared (``quoted retweets'') and the tone of these annotations (e.g., do users share out-group content with negative commentary?). We find clear patterns indicative of echo-chambers: the politically engaged users analyzed share in-group messages from elites 14 times more frequently than out-group messages; and in the rare instances when out-group information is shared, a non-trivial amount of times it is accompanied by negative comments. These patterns emerge after accounting for how many in-group versus out-group elites a person follows, and are robust to the political interest of the user or extremity of the elite accounts, the topic of the tweet, and the type of political elite source of the original message. In line with previous research, we also find that this echo chamber is especially pronounced among conservative users, who are about twice as likely as liberals to share in-group vs out-group content. These findings have important implications for how we theorize and study online echo chambers.


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