Improved Time Resolution Research Articles

Time resolution improvement of ultrasonic velocity profiler for flow over cylinder using EPOD method with optimally placed time-resolved sensors

Time resolution improvement of ultrasonic velocity profiler for flow over cylinder using EPOD method with optimally placed time-resolved sensors

FCS videos: Fluorescence correlation spectroscopy in space and time

Fluorescence Correlation Spectroscopy (FCS), invented more than 50 years ago is a widely used tool providing information on molecular processes in a variety of samples from materials to life sciences. In the last two decades FCS was multiplexed and ultimately made into an imaging technique that provided maps of molecular parameters over whole sample cross-section. However, it was still limited by a measurement time on the order of minutes. With the improvement of FCS time resolution to seconds using deep learning, we extend here FCS to so-called FCS videos that can provide information how the molecular parameters determined by Imaging FCS change in space and time. This opens up new possibilities for the investigation of molecular processes. Here, we demonstrate the feasibility of the approach and show FCS video applications to lipid bilayers and cell membranes.

Readout studies for the HIKE main electromagnetic calorimeter

The High-Intensity Kaon Experiment (HIKE) is a proposed future kaon experiment designed for the CERN SPS accelerator. To cope with a planned increase of beam intensity by a factor of 4 with respect to the current NA62 experiment, the new Main Electromagnetic Calorimeter (MEC) has to provide a similar improvement in time resolution over the current Liquid Krypton calorimeter, down to ≈100ps for a 40GeV photon, while maintaining a comparable energy and spatial resolution. To achieve these goals, the planned detector consists of a shashlik calorimeter paired with high-resolution analog to digital converter for both energy deposit and arrival time estimates, operating at fast sample rates (∼1GHz).This contribution describes a prototype of the readout system using commercial “off-the-shelf” boards. In particular, we focused on feature extraction and tested it using a pulse generator. We included a data readout logic based on the TCP/IP protocol allows for easy deployment in beam tests.

Effects of Relative Humidity and Phase on the Molecular Detection of Nascent Sea Spray Aerosol Using Extractive Electrospray Ionization.

Online mass spectrometry techniques, such as extractive electrospray ionization mass spectrometry (EESI-MS), present an attractive alternative for analyzing aerosol molecular composition due to reduced aerosol sample collection and handling times and improved time resolution. Recent studies show a dependence of EESI-MS sensitivity on particle size and mixing state. This study measured authentic sea spray aerosol (SSA) components generated during a phytoplankton bloom, specifically glycerol, palmitic acid, and potassium ions. We demonstrate temporal variability and trends dependent on specific biological processes occurring in seawater. We found that the EESI-MS sensitivity, after adjusting for pressure variations at the inlet and normalizing to the reagent ion, critically depends on the sample's relative humidity. Relevant SSA species exhibited heightened sensitivity at an elevated relative humidity near the deliquescence relative humidity of sea salt and poorer sensitivity with sparse detection below the efflorescence relative humidity. Modeling the reagent ion's diffusive depth demonstrates that the sample aerosol particle viscosity governs the relative humidity dependence because it modulates the particle's coagulation efficiency and distance the reagent ion diffuses and reacts with components in the particle bulk. The effects of particle size and mixing state are discussed, revealing improved sensitivity of phase-separated components present along the particle surface. This work highlights the importance of the particle phase state in detecting and quantifying molecular components within authentic and complex aerosol particles and the utility of EESI-MS for measuring SSA composition.

A New Methodology for High Spatiotemporal Resolution Measurements of Air Volatile Organic Compounds: From Sampling to Data Deconvolution.

Monitoring of volatile organic compounds (VOCs) in air is crucial for understanding their atmospheric impacts and advancing their emission reduction plans. This study presents an innovative integrated methodology suitable for achieving semireal-time high spatiotemporal resolution three-dimensional measurements of VOCs from ground to hundreds of meters above ground. The methodology integrates an active AirCore sampler, custom-designed for deployment from unmanned aerial vehicles (UAV), a proton-transfer-reaction mass spectrometry (PTR-MS) for sample analysis, and a data deconvolution algorithm for improved time resolution for measurements of multiple VOCs in air. The application of the deconvolution technique significantly improves the signal strength of data from PTR-MS analysis of AirCore samples and enhances their temporal resolution by 4 to 8 times to 4-11 s. A case study demonstrates that the methodology can achieve sample collection and analysis of VOCs within 45 min, resulting in >120-360 spatially resolved data points for each VOC measured and achieving a horizontal resolution of 20-55 m at a UAV flight speed of 5 m/s and a vertical resolution of 5 m. This methodology presents new possibilities for acquiring 3-dimensional spatial distributions of VOC concentrations, effectively tackling the longstanding challenge of characterizing three-dimensional VOC distributions in the lowest portion of the atmospheric boundary layer.

Data-volume reduction of optical vortex laser absorption spectroscopy by coarse-graining using a quadrant photodiode

We developed optical vortex laser absorption spectroscopy (OVLAS) to measure the transverse flow velocity relative to the probe beam. In our previous OVLAS setups, a camera is used in the measurement system. This approach constrained the time resolution by image data transfer time and required large computational resources due to the considerable amount of image data. In this paper, we discuss the coarse-graining of OVLAS as a method to improve time resolution and reduce computational resources achieved by replacing the camera with a quadrant photodiode (QPD). Measurement image data obtained from a camera was numerically coarse-grained to evaluate the feasibility of measurements using a QPD. Subsequently, the transverse flow velocity was measured by QPD. Measured transverse flow velocity had a mean absolute percentage error of 18%, confirming the practical validity of coarse-graining OVLAS. The data volume required to determine the flow velocity was reduced to 1/120 from the original OVLAS.

Multi-phase time-zooming high-precision ultrasonic water flow meter

In this study, we have developed a high-precision ultrasonic water flow meter with a 0.18 μm standard CMOS technology. Three methods are proposed to improve the performance: implementation of an active bandpass filter, threshold voltage optimization, and integration of a multi-phase time-zooming technique. The active bandpass filter effectively reduces noise in the received signal, thereby contributing to the overall accuracy of propagation measurements. Based on a threshold voltage generator, our proposed system identifies the optimum threshold voltage, ensuring robust noise durability. Furthermore, we have extended the conventional time-zooming technique by incorporating multiple phases of internal clocks. This innovative multiphase time-zooming technique offers a theoretical improvement in time resolution. The results demonstrate a remarkable suppression of flow rate measurement variations, achieving an impressive reduction to 1/10 of the original values. This affirms the effectiveness of the developed ultrasonic water flow meter in ensuring precise and reliable flow rate measurements.

Abstract B089: Oncogenic signaling and responses to treatment in RAS mutant cancers are mutation-specific

Abstract The KRAS, NRAS, and HRAS genes are frequently mutated in cancer, often at hotspots altering codons 12, 13, and 61. Yet how different RAS isoforms and mutations precisely regulate oncogenic signaling is still largely unknown. For example, the role of mutant RAS in driving overactivation of ERK signaling in cancer has long been elucidated, but its involvement in the oncogenic activation of PI3K is still controversial, and different studies have reported conflicting findings regarding the requirement of RAS for physiological and oncogenic PI3K signaling. One of the reasons for this lack of understanding has been the inability to directly target RAS, which has historically been circumvented through genomic perturbation and murine models. However, these approaches are limited because it is not possible to distinguish between the direct effects of RAS on PI3K and compensatory events that occur as an adaptation to the oncogene. With the discovery of RAS inhibitors, we can now directly interrogate the biological effects of RAS isoforms and hotspot mutations in cancer cells with improved time resolution. Here, we use RM-042, a first-in-class broad-spectrum RAS·GTP inhibitor (RASMULTI(ON)), to characterize the features and therapeutic vulnerabilities of mutant RAS signaling in human cancers. Through a detailed biochemical analysis of the signaling response to RAS and MEK inhibition, we reveal that RAS-mediated oncogenic signaling is largely independent of the mutant RAS isoform, rather depending on the mutant codon. Specifically, RASQ61X is exquisitely sensitive to MAPK pathway inhibition, confers near-complete independence of upstream regulation, and is impaired in its signaling to PI3K/Akt/mTOR. Conversely, RASG12X enables oncogenic signaling to both MAPK and PI3K/Akt/mTOR by amplifying upstream input from receptor tyrosine kinases (RTKs). Simultaneous RAS and RTK inhibition selectively impairs the growth of RASG12X-mutant tumors, irrespective of RAS isoform and tumor type, and we investigate the molecular mechanisms behind this synergistic effect. Additionally, we have generated a genetically modified mouse model (GEMM) harboring liver tumors induced by RASG12D or RASQ61R. In cell lines derived from these respective models, RASG12D but not RASQ61R activates PI3K upon growth-factor stimulation. Furthermore, in this system, RASQ61R is less oncogenic than RASG12D, an effect that can be rescued by the concurrent deletion of PTEN. These findings provide mechanistic insights into how mutant RAS interacts with upstream and downstream partners to maximize oncogenic signaling. Furthermore, our results shed light on the selective pressure driving the emergence of RASQ61X mutations as a mechanism of resistance against RTK inhibition: we show that colorectal cancer cells that acquire RASQ61X mutations to overcome EGFR inhibition become more independent of upstream signaling than those that acquire RASG12X. Citation Format: Michelangelo Marasco, Dinesh Kumar, Riccardo Mezzadra, Wei Luan, Ilinca Aricescu, Rona Yaeger, Vladimir Markov, Yu Zhu, Elisa de Stanchina, Scott Lowe, Sandra Misale, Neal Rosen. Oncogenic signaling and responses to treatment in RAS mutant cancers are mutation-specific [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B089.

Dual-Hyperspectral Optical Pump-Probe Microscopy with Single-Nanosecond Time Resolution.

In recent years, optical pump-probe microscopy (PPM) has become a vital technique for spatiotemporally imaging electronic excitations and charge-carrier transport in metals and semiconductors. However, existing methods are limited by mechanical delay lines with a probe time window up to several nanoseconds (ns) or monochromatic pump and probe sources with restricted spectral coverage and temporal resolution, hindering their amenability in studying relatively slow processes. To bridge these gaps, we introduce a dual-hyperspectral PPM setup with a time window spanning from nanoseconds to milliseconds and single-nanosecond resolution. Our method features a wide-field probe tunable from 370 to 1000 nm and a pump spanning from 330 nm to 16 μm. We apply this PPM technique to study various two-dimensional metal-halide perovskites (2D-MHPs) as representative semiconductors by imaging their transient responses near the exciton resonances under both above-band gap electronic pump excitation and below-band gap vibrational pump excitation. The resulting spatially and temporally resolved images reveal insights into heat dissipation, film uniformity, distribution of impurity phases, and film-substrate interfaces. In addition, the single-nanosecond temporal resolution enables the imaging of in-plane strain wave propagation in 2D-MHP single crystals. Our method, which offers extensive spectral tunability and significantly improved time resolution, opens new possibilities for the imaging of charge carriers, heat, and transient phase transformation processes, particularly in materials with spatially varying composition, strain, crystalline structure, and interfaces.

Probing Degradation in Lithium Ion Batteries with On-Chip Electrochemistry Mass Spectrometry.

The rapid uptake of lithium ion batteries (LIBs) for large scale electric vehicle and energy storage applications requires a deeper understanding of the degradation mechanisms. Capacity fade is due to the complex interplay between phase transitions, electrolyte decomposition and transition metal dissolution; many of these poorly understood parasitic reactions evolve gases as a side product. Here we present an on-chip electrochemistry mass spectrometry method that enables ultra-sensitive, fully quantified and time resolved detection of volatile species evolving from an operating LIB. The technique's electrochemical performance and mass transport is described by a finite element model and then experimentally used to demonstrate the variety of new insights into LIB performance. We show the versatility of the technique, including (a) observation of oxygen evolving from a LiNiMnCoO2 cathode and (b) the solid electrolyte interphase formation reaction on graphite in a variety of electrolytes, enabling the deconvolution of lithium inventory loss (c) the first direct evidence, by virtue of the improved time resolution of our technique, that carbon dioxide reduction to ethylene takes place in a lithium ion battery. The emerging insight will guide and validate battery lifetime models, as well as inform the design of longer lasting batteries.

Probing Degradation in Lithium Ion Batteries with On‐Chip Electrochemistry Mass Spectrometry**

AbstractThe rapid uptake of lithium ion batteries (LIBs) for large scale electric vehicle and energy storage applications requires a deeper understanding of the degradation mechanisms. Capacity fade is due to the complex interplay between phase transitions, electrolyte decomposition and transition metal dissolution; many of these poorly understood parasitic reactions evolve gases as a side product. Here we present an on‐chip electrochemistry mass spectrometry method that enables ultra‐sensitive, fully quantified and time resolved detection of volatile species evolving from an operating LIB. The technique's electrochemical performance and mass transport is described by a finite element model and then experimentally used to demonstrate the variety of new insights into LIB performance. We show the versatility of the technique, including (a) observation of oxygen evolving from a LiNiMnCoO2 cathode and (b) the solid electrolyte interphase formation reaction on graphite in a variety of electrolytes, enabling the deconvolution of lithium inventory loss (c) the first direct evidence, by virtue of the improved time resolution of our technique, that carbon dioxide reduction to ethylene takes place in a lithium ion battery. The emerging insight will guide and validate battery lifetime models, as well as inform the design of longer lasting batteries.

(Invited) Electrochemistry Combined in Situ Neutron Reflectometry: A Powerful Tool for a More Sustainable Environment

Neutrons, having extraordinary characteristics that include penetrating power, sensitivity to lighter elements (such as hydrogen and carbon), and magnetic moment, make neutron reflectometry an ideal candidate for examining surface and interfacial structures of thin films in a non-destructive and non-invasive fashion. Liquids Reflectometer (LR) at the Spallation Neutron Source at Oak Ridge National Laboratory measures specular and off specular neutron reflectivity in a horizontal sample geometry, and tracks changes of layer thickness, scattering length density, and roughness as a function of depth. The exceptional sample environment at LR offers the capability to conduct in situ electrochemistry to probe the morphological and structural changes of solid/liquid interfaces during operation as a function of chemical and electrochemical gradients over time. Furthermore, the time-resolved mode at LR can be carried out continuously over a reduced Q range and binned into 60-second intervals. The improved time resolution of the neutron reflectivity (NR) measurement can help elucidate the kinetic behavior of surface/interfaces under dynamic conditions and provide a unique perspective to the equilibrium study. In this talk, I will give a brief introduction on neutron reflectometry, the LR, and a variety of sample environments at the LR. I will focus on the electrochemical applications coupled with in situ NR measurement. In the end, I will provide a specific example of applications in electrochemically modulated separation for water remediation by using neutron reflectometry. With the rapid growth of human population, it is highly desirable to minimize energy and materials input in selective separations for a more sustainable environment. The study is critical for creating new, more selective separation systems through rationally design of the structure and operating conditions.

The time resolution improvement of Cherenkov-Radiator-Window Photomultiplier tube

The improvement of time resolution in time-of-flight positron emission tomography (TOF-PET) relies on the development of scintillation materials and photodetectors. With the introduction of Cherenkov TOF-PET, higher requirements have been placed on the intrinsic timing performance of photodetectors. Our team has proposed a Cherenkov Radiator Window Photomultiplier tube (CRW-FPMT) that uses the Cherenkov radiator directly as the light window, which eliminates the boundary between the scintillator and the photodetector for fast time resolution. This paper mainly discusses the factors influencing its time resolution and optimizes it to achieve a single photon time resolution of 27.2 ps.

Sparse SiPM Pixel Arrangement for a TOF-PET Detector Design that Achieves 100 ps Coincidence Time Resolution

Coupling silicon photomultipliers (SiPMs) to the side of a long and narrow scintillation crystal elements offers near-complete light extraction efficiency, independent of 511 keV photon interaction depth, and reduced scintillation light transit time jitter in its path toward the photodetector. With these advantages, significant improvements in PET detector coincidence time resolution (CTR) can be achieved compared to the traditional scintillation light readout configuration where an SiPM is coupled on the narrow end of crystals. Moreover, the arrangement of photosensors along the crystal’s side intrinsically provides a three-dimensional position sensing detector. One consideration for the side readout approach is the increase in the number of SiPMs required to read each crystal element. In this work, we investigate the achievable CTR when the number of SiPM elements coupled to the side of crystals is parametrically varied, including different crystal lengths and reflector configurations. A simulation model for CTR was validated against measurements with 3-20 mm length crystals employing side readout of scintillation light. The validated simulation model was used to parametrically investigate twenty-seven configurations of SiPMs arranged along the side of crystal elements. Reflector and sensor placement was parametrically varied to find configurations that optimize light collection efficiency, energy resolution, and CTR. One configuration achieved 101±1 ps FWHM CTR, while maintaining high light collection efficiency and good energy performance with a 33% reduction in photosensor area.

High-speed plasma measurements with a plasma impedance probe

Plasma impedance probes (PIPs) are a type of RF probe that primarily measures electron density. This work introduces two advancements: a streamlined analytical model for interpreting PIP-monopole measurements and techniques for achieving ≥1 MHz time-resolved PIP measurements. The model’s improvements include introducing sheath thickness as a measurement and providing a more accurate method for measuring electron density and damping. The model is validated by a quasi-static numerical simulation, which compares the simulation with measurements, identifies sources of error, and provides probe design criteria for minimizing uncertainty. The improved time resolution is achieved by introducing higher-frequency hardware, updated analysis algorithms, and a more rigorous approach to RF calibration. Finally, the new model and high-speed techniques are applied to two datasets: a 4 kHz plasma density oscillation resolved at 100 kHz with densities ranging between 2 × 1014 and 3 × 1015 m−3, and a 150 kHz oscillation resolved at 4 MHz with densities ranging between 4 × 1014 and 6 × 1014 m−3.

Nonlinear effects in optical trapping of titanium dioxide and diamond nanoparticles

Optical trapping in biophysics typically uses micron-scale beads made of materials like polystyrene or glass to probe the target of interest. Using smaller beads made of higher-index materials could increase the time resolution of these measurements. We characterized the trapping of nanoscale beads made of diamond and titanium dioxide (TiO2) in a single-beam gradient trap. Calculating theoretical expectations for the trapping stiffness of these beads, we found good agreement with measured values. Trap stiffness was significantly higher for TiO2 beads, owing to notable enhancement from nonlinear optical effects, not previously observed for continuous-wave trapping. Trap stiffness was over 6-fold higher for TiO2 beads than polystyrene beads of similar size at 70 mW laser power. These results suggest that diamond and TiO2 nanobeads can be used to improve time resolution in optical tweezers measurements.

TOPS fast timing plastic scintillators: Time and light output performances

Organic plastic scintillators are largely exploited for fast timing detectors thanks to their short scintillation time with respect to inorganic crystals. Plastic scintillators are cheap to produce, light and easy to manipulate (any standard mechanical workshop can handle the cutting, polishing, etc.). Nowadays, fastest plastic scintillators available on the market are EJ-232 (Eljen Technology) and BC-422 (Saint Gobain) with a rise time of 350ps, a decay time of 1.6ns and a pulse width of 1.3ns. Foreseen the performance improvement of timing detectors based on plastic scintillators, the development of faster scintillators can give a crucial contribution. TOPS is a project focused on the development of a new class of organic scintillators producing several liquid and solid samples. Comparing the light output and the timing properties of the samples exploiting minimum ionising particles, a selection of the highly performing TOPS scintillators has been investigated and characterised. The performance achieved with TOPS samples are extremely promising: a time resolution improvement from 10 up to 35% with respect to the EJ-232 has been demonstrated. In addition, an increase of light output has been obtained for all samples with a consequent potential improvement in energy resolution measurements of a factor up to 35%.

Integration of a superconducting nanowire single-photon detector into a confocal microscope for time-resolved photoluminescence (TRPL)-mapping: Sensitivity and time resolution.

This report highlights the combination of the MicroTime 100 upright confocal fluorescence lifetime microscope with a Single Quantum Eos Superconducting Nanowire Single-Photon Detector (SNSPD) system as a powerful tool for photophysical research and applications. We focus on an application in materials science, photoluminescence imaging, and lifetime characterization of Cu(InGa)Se2 (CIGS) devices intended for solar cells. We demonstrate improved sensitivity, signal-to-noise ratio, and time-resolution in combination with confocal spatial resolution in the near-infrared (NIR) range, specifically in the 1000-1300nm range. The MicroTime 100-Single Quantum Eos system shows two orders of magnitude higher signal-to-noise ratio for CIGS devices' photoluminescence imaging compared to a standard NIR-photomultiplier tube (NIR-PMT) and a three-fold improvement in time resolution, which is now limited by the laser pulse width. Our results demonstrate the advantages in terms of image quality and time resolution of SNSPDs technology for imaging in materials science.

Potential of Depth-of-Interaction-Based Detection Time Correction in Cherenkov Emitter Crystals for TOF-PET.

Cherenkov light can improve the timing resolution of Positron Emission Tomography (PET) radiation detectors, thanks to its prompt emission. Coincidence time resolutions (CTR) of ~30 ps were recently reported when using 3.2 mm-thick Cherenkov emitters. However, sufficient detection efficiency requires thicker crystals, causing the timing resolution to be degraded by the optical propagation inside the crystal. We report on depth-of-interaction (DOI) correction to mitigate the time-jitter due to the photon time spread in Cherenkov-based radiation detectors. We simulated the Cherenkov and scintillation light generation and propagation in 3 × 3 mm2 lead fluoride, lutetium oxyorthosilicate, bismuth germanate, thallium chloride, and thallium bromide. Crystal thicknesses varied from 9 to 18 mm with a 3-mm step. A DOI-based time correction showed a 2-to-2.5-fold reduction of the photon time spread across all materials and thicknesses. Results showed that highly refractive crystals, though producing more Cherenkov photons, were limited by an experimentally obtained high-cutoff wavelength and refractive index, restricting the propagation and extraction of Cherenkov photons mainly emitted at shorter wavelengths. Correcting the detection time using DOI information shows a high potential to mitigate the photon time spread. These simulations highlight the complexity of Cherenkov-based detectors and the competing factors in improving timing resolution.

Improved Estimation of Leaf Wetness Duration Using Deep-Learning-Based Time-Resolution Technique

Plant diseases are one of the leading causes of the loss of crops. Monitoring the plant growth conditions could help prevent the spread of diseases and ensure healthy agricultural productivity. A leaf wetness sensor (LWS) is used to detect wetness on the surface of the leaves. Leaf wetness duration (LWD) is an essential parameter that governs the possibility of the occurrence of diseases in plants. The sensor system used in this work for monitoring the environmental conditions transmits data every 30 min due to power consumption considerations. To improve the time resolution of the signal and accurate estimation of LWD, a deep-learning-based architecture is proposed. The data from LWS has been used to train the architecture and the results obtained have been compared with the existing methods to analyze its performance. Using the proposed architecture, the signal from LWS was benchmarked with the commercially available Phythos-31. The time resolution of data has been improved from ±30 to ±4 min. The average signal-to-noise ratio (SNR) values for three test signals with improved time resolution have increased from 19.36 to 22.16 dB. Similarly, the average root means square error (RMSE) of the estimated LWD values after time resolution improved from 0.55 to 0.20. During the experimental analysis, it has been observed that the proposed architecture estimates the LWD values better compared to the other time-resolution techniques.