Study of chemoconvection by PIV at neutralization reaction under normal and modulated gravity

2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Elena Mosheva ◽  
Nikolai Kozlov
2017 ◽  
Vol 96 (5) ◽  
Author(s):  
Dmitry Bratsun ◽  
Alexey Mizev ◽  
Elena Mosheva ◽  
Konstantin Kostarev

Nature ◽  
1963 ◽  
Vol 199 (4893) ◽  
pp. 595-596 ◽  
Author(s):  
HAROLD BEHRENS ◽  
JOHN R. TOTTER ◽  
GEORGE E. PHILBROOK

2016 ◽  
Vol 17 (3) ◽  
pp. 509-522 ◽  
Author(s):  
James M. Nyachwaya

The objective of this study was to examine college general chemistry students' conceptual understanding and language fluency in the context of the topic of acids and bases. 115 students worked in groups of 2–4 to complete an activity on conductometry, where they were given a scenario in which a titration of sodium hydroxide solution and dilute hydrochloric acid was tracked by measuring electrical conductivity. Students were asked to write a balanced equation for the reaction, provide a particulate level drawing of the reactants and products, write a net ionic equation for the reaction, predict how electrical conductivity would change with the addition of sodium hydroxide to the acid, provide a sketch of their prediction, and explain their sketch. As students worked on the activity, conversations in their groups were audio recorded. Their written responses and audio conversations were analyzed to decipher conceptual understanding and language fluency. Results showed widespread lack of conceptual understanding as well as a lack of language fluency. Students struggled with very basic ideas regarding acid–base chemistry, such as identifying the right species involved in the neutralization reaction, and providing symbolic and sub-microscopic representations (an aspect of the language of chemistry) of the acid–base reaction. Most students could not accurately predict how electrical conductivity would change as the neutralization reaction progressed. None of the groups provided an accurate sketch depicting the trend of electrical conductivity. Most of the groups did not correctly apply acid–base neutralization ideas to the context of conductometry, indicating that students were not able to transfer knowledge of acid–base neutralization to this new context.


2017 ◽  
Vol 15 (2) ◽  
pp. 162-169 ◽  
Author(s):  
Sydney Peng ◽  
Zhi-Teng Lai ◽  
Ding-Wei Hong ◽  
I-Ming Chu ◽  
Po-Liang Lai

Background The aim of this study was to develop a minimally invasive hydrogel system that can release strontium ions, an element that has been shown to increase osteoblast proliferation and prohibit bone resorption, in a controlled manner. Methods SrCO3 was selected as the salt of choice due to potential acid neutralization reaction between SrCO3 and degradation by-products of methoxy(polyethylene glycol)- co-poly(lactic- co-glycolic acid) (mPEG-PLGA): namely, lactic acid and glycolic acid. SrCO3 was incorporated into mPEG-PLGA hydrogel, and the system was assessed for gelation properties, drug release and biocompatibility. Results SrCO3 incorporation at hydrogel to SrCO3 ratios of 5:1, 3:1 and 1:1 (wt%) did not compromise the thermosensitivity of mPEG-PLGA hydrogels. Furthermore, incorporation of SrCO3 at 1:1 ratio prevented copolymer self-catalysis and decreased hydrogel weight loss from 85% to 61% in vitro after 30 days. During the 30-day time frame, zero-order strontium release was observed and was correlated to hydrogel degradation and acidity. The addition of SrCO3 also improved in vivo hydrogel biocompatibility, due to moderation of acidic microenvironment and amelioration of inflammatory response. Conclusions These results showed that the described system is suitable for the extended release of strontium and exhibits potential for localized treatment for osteoporosis or as a bone void filler.


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