Objective Interface pressure, the sine qua non for compression therapy, is rarely measured in clinical practice and scientific research. The goal of this study aimed to compare and examine the accuracy between a commercially available piezoresistive sensor and PicoPress® (Microlab, Padua, Italy) using the cylinder cuff model to measure in-vitro interface pressure. Method Ten piezoresistive sensors were calibrated using the National Institute of Standard and Technology certified manometer, and compared to PicoPress® using cylinder cuff model from 20 to 120 mmHg. Two statistical analyses were performed: (a) two-sample t-test to compare the front to back surface of the piezoresistive sensors using mean pressure value and (b) one-sample paired t-test to compare the front and back surface of the piezoresistive sensors to PicoPress® and true pressure using mean pressure value. Result There was no difference in interface pressure measurement between the front and back surface of the piezoresistive sensors (P > 0.05). Using mean pressure value, there was no significant difference between the front surface, back surface of the piezoresistive sensors, and PicoPress® (P > 0.05). Standard deviation was larger for the piezoresistive sensors than PicoPress® at any given pressure and this difference was more pronounced in the higher pressure range. Conclusion Piezoresistive sensor may represent a viable alternative to PicoPress® in interface pressure measurement.
Manual micropipettes are the most heavily used liquid handling devices in biological and chemical laboratories; however, they suffer from low precision for volumes under 1 l and inevitable human errors. For a manual device, the human errors introduced pose potential risks of failed experiments, inaccurate results, and financial costs. Meanwhile, low precision under 1l can cause severe quantification errors and high heterogeneity of outcomes, becoming a bottleneck of reaction miniaturization for quantitative research in biochemical labs. Here, we report Dotette, a programmable, plug-and-play microfluidic pipetting device based on nanoliter liquid printing. With automated control, protocols designed on computers can be directly downloaded into Dotette, enabling programmable operation processes. Utilizing continuous nanoliter droplet dispensing, the precision of the volume control has been successfully improved from traditional 20%-50% to less than 5% in the range of 100 nl to 1000 nl. Such a highly automated, plug-and-play add-on to existing pipetting devices not only improves precise quantification in low-volume liquid handling and reduces chemical consumptions but also facilitates and automates a variety of biochemical and biological operations.
Natural genetic promoters are regulated by multiple cis and trans regulatory factors. For quantitative studies of these promoters, the concentration of only a single factor is typically varied to obtain dose response or transfer function of the promoters with respect to the factor. Such design of experiments has limited our ability to understand quantitative, combinatorial interactions between multiple regulatory factors at promoters. The limitation is primarily due to the intractable number of experimental combinations that arise from multifactorial design of experiments. To overcome this major limitation, we integrate impact printing and cell-free systems to enable multi-dimensional studies of genetic promoters. We first present a gradient printing system which comprises parallel piezoelectric cantilever beams as a scalable actuator array to generate droplets with tunable volumes in the range of 100pL – 10nL, which facilitates highly accurate direct dilutions in the range of 1 – 10,000 fold in a 1μL drop. Next, we apply this technology to study interactions between three regulatory factors at a synthetic genetic promoter. Finally, a mathematical model of gene regulatory modules is established using the multi-parametric and multi-dimensional data. Our work creates a new frontier in the use of cell-free systems and droplet printing for multi-dimensional studies of synthetic genetic constructs.
The use of Si and nitrogen-doped graphene to fabricate composite anodes in lithium-ion batteries (LIBs) is attracting intense attention. However, the reported strategies are limited to achieving a cost-effective, scalable, and facile approach. In particular, many reports on Si/N-graphene (N-Gra) anodes cannot achieve a high first discharge capacity while retaining a high Coulombic efficiency (CE). Herein, we report a Si@N-Gra composite with core−shelled microballs of Si NPs and electrochemically exfoliated graphene by NH 3 as a nitrogen source. We use H 2 and NH 3 to control the O and N content and to optimize the anode performance.
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