Real-Time Tunable Dynamic Range for Calibration-Free Biomolecular Measurements with a Temperature-Modulated Electrochemical Aptamer-Based Sensor in an Unprocessed Actual Sample

2021 ◽  
Author(s):  
Zhi-Min Chen ◽  
Qi Mou ◽  
Sheng-Hong Wu ◽  
Yu Xie ◽  
Kalle Salminen ◽  
...  
Keyword(s):  
Real Time ◽  
Dynamic Range ◽  
Actual Sample ◽  
Calibration Free

scholarly journals Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3634 ◽  
Author(s):  
Srijit Nair ◽  
Juan Gomez-Cruz ◽  
Ángel Manjarrez-Hernandez ◽  
Gabriel Ascanio ◽  
Ribal Sabat ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Real Time ◽  
Surface Relief ◽  
Bacterial Infections ◽  
Dynamic Range ◽  
Incident Light ◽  
Public Healthcare ◽  
Label Free Detection ◽  
Surface Relief Gratings ◽  
Tract Infections

Urinary tract infections (UTIs) are one of the major burdens on public healthcare worldwide. One of the primary causes of UTIs is the invasion of the urinary tract by uropathogenic Escherichia coli (UPEC). Improper treatment of bacterial infections like UTIs with broad-spectrum antibiotics has contributed to the rise of antimicrobial resistance, necessitating the development of an inexpensive, rapid and accurate detection of UPEC. Here, we present real-time, selective and label-free detection of UPEC using crossed surface-relief gratings (CSRGs) as nanometallic sensors incorporated into an optical sensing platform. CSRGs enable real-time sensing due to their unique surface plasmon resonance (SPR)-based light energy exchange, resulting in detection of a very-narrow-bandwidth SPR signal after the elimination of residual incident light. The platform’s sensing ability is experimentally demonstrated by the detection of bulk refractive index (RI) changes, with a bulk sensitivity of 382.2 nm/RIU and a resolution in the order of 10−6 RIU. We also demonstrate, for the first time, CSRG-based real-time selective capture and detection of UPEC in phosphate-buffered saline (PBS) solution, in clinically relevant concentrations, as opposed to other UTI-causing Gram-negative bacteria. The platform’s detection limit is calculated to be 105 CFU/mL (concentration on par with the clinical threshold for UTI diagnosis), with a dynamic range spanning four orders of magnitude. This work paves the way for the development of inexpensive point-of-care diagnosis devices focusing on effective treatment of UTIs, which are a burden on public healthcare due to the rise in the number of cases and their recurrences in the recent past.

Real-Time Measurement Method of Doppler Based on GPS Carrier Signals

2012 ◽  
Vol 226-228 ◽  
pp. 2050-2055 ◽  
Author(s):  
Shao Feng Dong ◽  
Bao Qiang Du ◽  
Wei Zhou
Keyword(s):  
Frequency Shift ◽  
Real Time ◽  
Measurement Method ◽  
Dynamic Range ◽  
Time Synchronization ◽  
Influencing Factor ◽  
Doppler Frequency ◽  
Time Measurement ◽  
Time Frequency ◽  
Real Time Measurement

According to Doppler effect of satellite on the time synchronization technology between satellite and the ground station, a real-time measurement method of Doppler is proposed based on GPS carrier signals. Using Doppler observations from GPS receiver, the method can real-timely measure Doppler frequency shift of GPS including dynamic Doppler and media Doppler whose error can be timely modified in the receiver end. Simulation results show that the frequency shift caused by dynamic Doppler, a main influencing factor in the course of transmission of time-frequency signal by GPS satellite, is between plus or minus several thousands Hz. Comparing to traditional measurement method of Doppler, the method makes it possible to fast track phase of signal in large dynamic range in synchronous technology.

scholarly journals Use of Ethidium Monoazide and PCR in Combination for Quantification of Viable and Dead Cells in Complex Samples

2005 ◽  
Vol 71 (2) ◽  
pp. 1018-1024 ◽  
Author(s):  
Knut Rudi ◽  
Birgitte Moen ◽  
Signe Marie Drømtorp ◽  
Askild L. Holck
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Dynamic Range ◽  
Covalent Binding ◽  
Biological Research ◽  
Complex Samples ◽  
Ethidium Monoazide ◽  
Food Borne ◽  
Pcr Method ◽  
Membrane Cell

ABSTRACT The distinction between viable and dead cells is a major issue in many aspects of biological research. The current technologies for determining viable versus dead cells cannot readily be used for quantitative differentiation of specific cells in mixed populations. This is a serious limitation. We have solved this problem by developing a new concept with the viable/dead stain ethidium monoazide (EMA) in combination with real-time PCR (EMA-PCR). A dynamic range of approximately 4 log10 was obtained for the EMA-PCR viable/dead assay. Viable/dead differentiation is obtained by covalent binding of EMA to DNA in dead cells by photoactivation. EMA penetrates only dead cells with compromised membrane/cell wall systems. DNA covalently bound to EMA cannot be PCR amplified. Thus, only DNA from viable cells can be detected. We evaluated EMA-PCR with the major food-borne bacterium Campylobacter jejuni as an example. Traditional diagnosis of this bacterium is very difficult due to its specific growth requirements and because it may enter a state where it is viable but not cultivable. The conditions analyzed included detection in mixed and natural samples, survival in food, and survival after disinfection or antibiotic treatment. We obtained reliable viable/dead quantifications for all conditions tested. Comparison with standard fluorescence-based viable/dead techniques showed that the EMA-PCR has a broader dynamic range and enables quantification in mixed and complex samples. In conclusion, EMA-PCR offers a novel real-time PCR method for quantitative distinction between viable and dead cells with potentially very wide application.

Development of a real-time reverse transcription-PCR assay to detect and quantify group A rotavirus equine-like G3 strains

2021 ◽  
Author(s):  
Eric M. Katz ◽  
Mathew D. Esona ◽  
Rashi Gautam ◽  
Michael D. Bowen
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Reverse Transcription ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Human Populations ◽  
Pcr Assay ◽  
Group A Rotavirus ◽  
Reverse Transcription Pcr ◽  
Group A

Since 2013, group A rotavirus strains characterized as novel DS-1-like inter-genogroup reassortant ‘equine-like G3’ strains have emerged and spread across five continents among human populations in at least 14 countries. Here we report a novel one-step TaqMan quantitative real-time reverse transcription-PCR assay developed to genotype and quantify the viral load for samples containing rotavirus equine-like G3 strains. Using a universal G forward primer and a newly designed reverse primer and TaqMan probe, we developed and validated an assay with a linear dynamic range of 2.3 × 10 9 – 227 copies per reaction and a limit of detection of 227 copies. The percent positive agreement, percent negative agreement, and precision of our assay were 100.00%, 99.63%, and 100.00%, respectively. This assay can simultaneously detect and quantify the viral load for samples containing DS-1-like inter-genogroup reassortant equine-like G3 strains with high sensitivity and specificity, faster turnaround time, and decreased cost and will be valuable for high-throughput screening of stool samples collected to monitor equine-like G3 strain prevalence and circulation among human populations throughout the world.

scholarly journals Construction of a Nanosensor for Non-Invasive Imaging of Hydrogen Peroxide Levels in Living Cells

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 430
Author(s):  
Amreen ◽  
Hayssam M. Ali ◽  
Mohammad Ahmad ◽  
Mohamed Z. M. Salem ◽  
Altaf Ahmad
Keyword(s):  
Hydrogen Peroxide ◽  
Real Time ◽  
Mammalian Cells ◽  
Dynamic Range ◽  
Resonance Energy ◽  
Living Cells ◽  
Stress Conditions ◽  
Live Cells ◽  
Cell Physiology ◽  
Broad Dynamic Range

Hydrogen peroxide (H2O2) serves fundamental regulatory functions in metabolism beyond the role as damage signal. During stress conditions, the level of H2O2 increases in the cells and causes oxidative stress, which interferes with normal cell growth in plants and animals. The H2O2 also acts as a central signaling molecule and regulates numerous pathways in living cells. To better understand the generation of H2O2 in environmental responses and its role in cellular signaling, there is a need to study the flux of H2O2 at high spatio–temporal resolution in a real-time fashion. Herein, we developed a genetically encoded Fluorescence Resonance Energy Transfer (FRET)-based nanosensor (FLIP-H2O2) by sandwiching the regulatory domain (RD) of OxyR between two fluorescent moieties, namely ECFP and mVenus. This nanosensor was pH stable, highly selective to H2O2, and showed insensitivity to other oxidants like superoxide anions, nitric oxide, and peroxynitrite. The FLIP-H2O2 demonstrated a broad dynamic range and having a binding affinity (Kd) of 247 µM. Expression of sensor protein in living bacterial, yeast, and mammalian cells showed the localization of the sensor in the cytosol. The flux of H2O2 was measured in these live cells using the FLIP-H2O2 under stress conditions or by externally providing the ligand. Time-dependent FRET-ratio changes were recorded, which correspond to the presence of H2O2. Using this sensor, real-time information of the H2O2 level can be obtained non-invasively. Thus, this nanosensor would help to understand the adverse effect of H2O2 on cell physiology and its role in redox signaling.

scholarly journals Cloning and evaluation of reference genes for quantitative real-time PCR analysis inAmorphophallus

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3260 ◽  
Author(s):  
Kai Wang ◽  
Yi Niu ◽  
Qijun Wang ◽  
Haili Liu ◽  
Yi Jin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Real Time ◽  
Reference Genes ◽  
Dynamic Range ◽  
Expression Profiles ◽  
Mrna Levels ◽  
Expression Stability ◽  
Degenerate Primers ◽  
Different Tissues

Quantitative real-time reverse transcription PCR (RT-qPCR) has been widely used in the detection and quantification of gene expression levels because of its high accuracy, sensitivity, and reproducibility as well as its large dynamic range. However, the reliability and accuracy of RT-qPCR depends on accurate transcript normalization using stably expressed reference genes.Amorphophallusis a perennial plant with a high content of konjac glucomannan (KGM) in its corm. This crop has been used as a food source and as a traditional medicine for thousands of years. Without adequate knowledge of gene expression profiles, there has been no report of validated reference genes inAmorphophallus. In this study, nine genes that are usually used as reference genes in other crops were selected as candidate reference genes. These putative sequences of these genesAmorphophalluswere cloned by the use of degenerate primers. The expression stability of each gene was assessed in different tissues and under two abiotic stresses (heat and waterlogging) inA. albusandA. konjac. Three distinct algorithms were used to evaluate the expression stability of the candidate reference genes. The results demonstrated thatEF1-a,EIF4A,H3andUBQwere the best reference genes under heat stress inAmorphophallus. Furthermore,EF1-a,EIF4A,TUB, andRPwere the best reference genes in waterlogged conditions. By comparing different tissues from all samples, we determined thatEF1-α,EIF4A,andCYPwere stable in these sets. In addition, the suitability of these reference genes was confirmed by validating the expression of a gene encoding the small heat shock proteinSHSP, which is related to heat stress inAmorphophallus. In sum,EF1-αandEIF4Awere the two best reference genes for normalizing mRNA levels in different tissues and under various stress treatments, and we suggest using one of these genes in combination with 1 or 2 reference genes associated with different biological processes to normalize gene expression. Our results will provide researchers with appropriate reference genes for further gene expression quantification using RT-qPCR inAmorphophallus.

scholarly journals Compressed Sensing of Scanning Transmission Electron Microscopy (STEM) With Nonrectangular Scans

2018 ◽  
Vol 24 (6) ◽  
pp. 623-633 ◽  
Author(s):  
Xin Li ◽  
Ondrej Dyck ◽  
Sergei V. Kalinin ◽  
Stephen Jesse
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Real Time ◽  
Scanning Transmission Electron Microscopy ◽  
High Speed ◽  
Dynamic Range ◽  
Extended Defects ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractScanning transmission electron microscopy (STEM) has become the main stay for materials characterization on atomic level, with applications ranging from visualization of localized and extended defects to mapping order parameter fields. In recent years, attention has focused on the potential of STEM to explore beam induced chemical processes and especially manipulating atomic motion, enabling atom-by-atom fabrication. These applications, as well as traditional imaging of beam sensitive materials, necessitate increasing the dynamic range of STEM in imaging and manipulation modes, and increasing the absolute scanning speed which can be achieved by combining sparse sensing methods with nonrectangular scanning trajectories. Here we have developed a general method for real-time reconstruction of sparsely sampled images from high-speed, noninvasive and diverse scanning pathways, including spiral scan and Lissajous scan. This approach is demonstrated on both the synthetic data and experimental STEM data on the beam sensitive material graphene. This work opens the door for comprehensive investigation and optimal design of dose efficient scanning strategies and real-time adaptive inference and control of e-beam induced atomic fabrication.

Better Utilization of SAR Dynamic Range

1977 ◽  
Vol 21 (3) ◽  
pp. 235-240
Author(s):  
Edward J. Dragavon
Keyword(s):  
Computer Simulation ◽  
Synthetic Aperture Radar ◽  
Real Time ◽  
Image Enhancement ◽  
Dynamic Range ◽  
Synthetic Aperture ◽  
Analytic Methods ◽  
Sar Imagery ◽  
Gray Shade ◽  
Aperture Radar

Three general classes of image enhancement techniques for synthetic aperture radar (SAR) video were investigated through non-real-time computer simulation. The general categories were 1) monochromatic adaptive gray shade transformations, 2) pseudocolor encoding, and 3) feature analytic methods. The class of feature analytic techniques was found to have the greatest potential for improving the operational utility of SAR imagery.

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