29 research outputs found
Continuous and Noninvasive Measurement of Arterial Pulse Pressure and Pressure Waveform using an Image-free Ultrasound System
The local beat-to-beat local pulse pressure (PP) and blood pressure waveform
of arteries, especially central arteries, are important indicators of the
course of cardiovascular diseases (CVDs). Nevertheless, noninvasive measurement
of them remains a challenge in the clinic. This work presents a three-element
image-free ultrasound system with a low-computational method for real-time
measurement of local pulse wave velocity (PWV) and diameter waveforms, enabling
real-time and noninvasive continuous PP and blood pressure waveforms
measurement without calibration. The developed system has been well-validated
in vitro and in vivo. In in vitro cardiovascular phantom experiments, the
results demonstrated high accuracy in the measurement of PP (error < 3 mmHg)
and blood pressure waveform (root-mean-square-errors (RMSE) < 2 mmHg,
correlation coefficient (r) > textgreater 0.99). In subsequent human carotid
experiments, the system was compared with an arterial tonometer, which showed
excellent PP accuracy (mean absolute error (MAE) = 3.7 +- 3.4 mmHg) and
pressure waveform similarity (RMSE = 3.7 +- 1.6 mmHg, r = 0.98 +- 0.01).
Furthermore, comparative experiments with the volume clamp device demonstrated
the system's ability to accurately trace blood pressure changes (induced by
deep breathing) over a period of one minute, with the MAE of DBP, MAP, and SBP
within 5 +- 8 mmHg. The present results demonstrate the accuracy and
reliability of the developed system for continuous and noninvasive measurement
of arterial PP and blood pressure waveform measurements, with potential
applications in the diagnosis and prevention of CVDs.Comment: 13 pages, 12 figure
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Publisher Correction: Copper adparticle enabled selective electrosynthesis of n-propanol.
An amendment to this paper has been published and can be accessed via a link at the top of the paper
Subsequent monitoring of ferric ion and ascorbic acid using graphdiyne quantum dots-based optical sensors
Graphdiyne (GDY) as an emerging carbon nanomaterial has attracted increasing attention because of its uniformly distributed pores, highly π-conjugated, and tunable electronic properties. These excellent characteristics have been widely explored in the fields of energy storage and catalysts, yet there is no report on the development of sensors based on the outstanding optical property of GDY. In this paper, a new sensing mechanism is reported built upon the synergistic effect between inner filter effect and photoinduced electron transfer. We constructed a novel nanosensor based upon the newly-synthesized nanomaterial and demonstrated a sensitive and selective detection for both Fe3+ ion and ascorbic acid, enabling the measurements in real clinical samples. For the first time fluorescent graphdiyne oxide quantum dots (GDYO-QDs) were prepared using a facile ultrasonic protocol and they were characterized with a range of techniques, showing a strong blue-green emission with 14.6% quantum yield. The emission is quenched efficiently by Fe3+ and recovered by ascorbic acid (AA). We have fabricated an off/on fluorescent nanosensors based on this unique property. The nanosensors are able to detect Fe3+ as low as 95 nmol L−1 with a promising dynamic range from 0.25 to 200 μmol L−1. The LOD of AA was 2.5 μmol L−1, with range of 10–500 μmol L−1. It showed a promising capability to detect Fe3+ and AA in serum samples
A Theory of Dynamic Biofuel Tax Credit
In this paper, we set up a social cost minimization problem for a government. Using dynamic optimization tools, we analytically shows how exogenous parameters could affect
the optimal social cost and the optimal tax credit policy path
Formation of Carbon Fiber Florets using Copper Tartrate Catalysts Precursors
A novel method was investigated to synthesize carbon fiber florets using copper tartrate catalyst precursors by catalytic chemical vapor deposition at 300 °C. Samples were obtained for different growth periods. On the basis of electron microscopy and X-ray diffraction characterizations, a growth model for the formation of fiber florets was proposed as well as the branching of fibers nearby copper catalyst particles. These findings could facilitate the understanding of the catalytic growth process of different carbon materials including carbon nanotubes and graphene under different reaction parameters