We developed a comprehensive training module for the undergraduates majoring in chemical education with a simple microfluidic experiment. The students were required to read a scientific reference offered by the instructor, then design and implement a microfluidic experiment for real sample analysis by making some modifications to the method described in the reference. Finally, the students were required to evaluate the analytical results with a standard method and write an experimental report. This reading−designing−implementing−evaluating−writing (RDIEW) module aims to enhance the students' experimental skills as well as their abilities at designing experiments and reading English scientific literature. More importantly, the concept of microfluidic analysis was successfully introduced to the undergraduates majoring in chemical education by this training module, which may facilitate the introduction of microfluidic devices to chemistry courses at high schools. This 1 week (3 h per day) module was developed for the undergraduates majoring in chemical education at the sixth semester. The feedback from the students indicated that the learning objectives of this training module were met.
The research on driver fatigue detection is of great significance to improve driving safety. This paper proposes a real-time comprehensive driver fatigue detection algorithm based on facial landmarks to improve the detection accuracy, which detects the driver’s fatigue status by using facial video sequences without equipping their bodies with other intelligent devices. A tasks-constrained deep convolutional network is constructed to detect the face region based on 68 key points, which can solve the optimization problem caused by the different convergence speeds of each task. According to the real-time facial video images, the eye feature of the eye aspect ratio (EAR), mouth aspect ratio (MAR) and percentage of eye closure time (PERCLOS) are calculated based on facial landmarks. A comprehensive driver fatigue assessment model is established to assess the fatigue status of drivers through eye/mouth feature selection. After a series of comparative experiments, the results show that this proposed algorithm achieves good performance in both accuracy and speed for driver fatigue detection.
We described an indicator-free
argentometric titration strategy
using a microfluidic paper-based analytical device. This strategy
was based on the formation of insoluble silver salts by reactions
occurring between analytes and titrant (Ag
+
) on a paper
channel. After the insoluble silver salts were formed and precipitated
on the channel, the paper substrate modified with the surplus titrant
on the channel turned reddish-brown by exposure of the devices to
a simple and cheap UV light source for 5 min, generating a colored
band on the channel. Distance-based detection of chloride was achieved
by measuring the length of the colored band with a detection limit
of 1.7 mg L
–1
Cl
–
. This method
was used to detect chlorides in tap water, with an analytical result
(10.1 ± 1.2 mg L
–1
) agreeing well with that
obtained by a classical conventional precipitation titration (9.8
mg L
–1
), which was based on the measurement of the
consumed volume of titrant. This paper-based precipitation titration
method is free of skilled personnel and has advantages of low reagent/sample
consumption, disposability, portability, and simple operation over
the conventional precipitation titration. More importantly, being
free of any indicator, this method may be used to detect more species
than the conventional precipitation titrations, which are limited
by the indicator, for example, CO
3
2–
and
SO
4
2–
, which could form insoluble silver
salts in aqueous liquids. Additionally, comparing with most of those
paper-based titrimetry reported previously, this presented precipitation
titration is free of any indicator or ion selective electrode to detect
the end point of titration.
We described an instrument-free method for quantitative analysis of the total content of tea polyphenols by measurement of the length of a coloured band. Polyphenols react with ferrous ions to form a colourless ferrous-polyphenols complex on cotton threads, which could be adsorbed on the threads. The complex was then oxidized to form a blue-black ferric-polyphenols complex, generating a blue-black band on the cotton thread. The length of this blue-black band was then measured to detect the total content of polyphenols. The advantages of this method include low cost, rapid analysis, low consumption, easy fabrication and operation. Furthermore, the digital instrument (scanner or camera) as well as the image processing software are not required. This proposed method was used to detect polyphenols in tea leaf extracts with an analytical result agreeing well with that obtained by a standard method, which demonstrates its potential in monitoring of tea leaf quality, especially in resource-limited regions and settings.
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