Time Scale Of Minutes Research Articles

Light activation of Orange Carotenoid Protein reveals bicycle-pedal single-bond isomerization

Orange Carotenoid protein (OCP) is the only known photoreceptor which uses carotenoid for its activation. It is found exclusively in cyanobacteria, where it functions to control light-harvesting of the photosynthetic machinery. However, the photochemical reactions and structural dynamics of this unique photosensing process are not yet resolved. We present time-resolved crystal structures at second-to-minute delays under bright illumination, capturing the early photoproduct and structures of the subsequent reaction intermediates. The first stable photoproduct shows concerted isomerization of C9’-C8’ and C7’-C6’ single bonds in the bicycle-pedal (s-BP) manner and structural changes in the N-terminal domain with minute timescale kinetics. These are followed by a thermally-driven recovery of the s-BP isomer to the dark state carotenoid configuration. Structural changes propagate to the C-terminal domain, resulting, at later time, in the H-bond rupture of the carotenoid keto group with protein residues. Solution FTIR and UV/Vis spectroscopy support the single bond isomerization of the carotenoid in the s-BP manner and subsequent thermal structural reactions as the basis of OCP photoreception.

Seasonal Slow Landslide Displacement Is Accommodated by mm‐Scale Stick‐Slip Events

AbstractLike faults, landslides can slip slowly for decades or accelerate catastrophically. However, whereas experimentally derived friction laws provide mechanistically based explanations for similarly diverse behavior on faults, little monitoring exists over the temporal and spatial scales required to more clearly illuminate the mechanics of landslide friction. Here we show that displacement of an active slow landslide is accommodated primarily through mm‐scale stick‐slip events that recur on timescales of minutes to hours on asperities that are small (<100 m) relative to the landslide. The frequency of slip events tracks both landslide velocity and pore fluid pressure. The stick‐slip nature demonstrates by itself that slow slip is governed, at least in part, by velocity‐weakening frictional asperities. This observation, in combination with the sensitivity of slow slip to pore fluid pressure and the small relative scale of asperities, suggests similarities between slow slip in landslides and episodic slow slip along faults.

Rapid Online Oxidation of Proteins and Peptides via Electrospray-Accelerated Ozonation.

Mass spectrometry-based analyses of protein conformation continue to grow in utilization due their speed, low sample requirements, and applicability to most protein systems. These techniques typically rely on chemical derivatization of proteins and as with all label-based analyses must ensure the integrity of the protein conformation throughout the duration of the labeling reaction. Hydroxyl radical footprinting of proteins and the recently developed fast fluoroalkylation of proteins attempt to bypass this consideration via rapid reactions that occur on time scales faster than protein folding, but they often require microfluidic setups or electromagnetic radiation sources. In this work, we demonstrate that ozonation of proteins and peptides, which normally occurs in the second to minute time scales, can be accelerated to the submillisecond to millisecond time scale with an electrospray ionization source. This rapid ozonation results in selective labeling of tryptophan and methionine residues. When applied to cytochrome C and carbonic anhydrase, this labeling technique is sensitive to solution conditions and correlates with solution-phase analyses of conformation. While significant work is still needed to characterize this fast chemical labeling strategy, it requires no complicated sample handling, electromagnetic radiation sources, or microfluidic systems outside of the electrospray source and may represent a facile alternative to other rapid labeling technologies that are utilized today.

Minimizing Motion Artifacts in Intravital Microscopy Using the Sedative Effect of Dexmedetomidine.

Among intravital imaging instruments, the intravital two-photon fluorescence excitation microscope has the advantage of enabling real-time 3D fluorescence imaging deep into cells and tissues, with reduced photobleaching and photodamage compared with conventional intravital confocal microscopes. However, excessive motion of organs due to involuntary movement such as breathing may result in out-of-focus images and severe fluorescence intensity fluctuations, which hinder meaningful imaging and analysis. The clinically approved alpha-2 adrenergic receptor agonist dexmedetomidine was administered to mice during two-photon fluorescence intravital imaging to alleviate this problem. As dexmedetomidine blocks the release of the neurotransmitter norepinephrine, pain is suppressed, blood pressure is reduced, and a sedation effect is observed. By tracking the quality of focus and stability of detected fluorescence in two-photon fluorescence images of fluorescein isothiocyanate-sensitized liver vasculature in vivo, we demonstrated that intravascular dexmedetomidine can reduce fluorescence fluctuations caused by respiration on a timescale of minutes in mice, improving image quality and resolution. The results indicate that short-term dexmedetomidine treatment is suitable for reducing involuntary motion in preclinical intravital imaging studies. This method may be applicable to other animal models.

Outcomes and Side Effects of Preoperative Chemoradiotherapy for Locally Advanced Upper Rectal Cancer

The benefit of neoadjuvant (chemo) radiotherapy for locally advanced upper rectal tumors remains controversial. Thus, we aimed to evaluate the outcome of patients with stage II or-III upper rectal cancer undergoing neoadjuvant (chemo) radiotherapy followed by total mesorectal excision in our institution. From April 2004 to October 2019, all patients with stage II or III upper rectal cancer treated with neoadjuvant (chemo) radiotherapy followed by total mesorectal excision were identified from our database. Overall survival, progression-free survival, and local recurrence were assessed using the Kaplan-Meier method. Acute and late treatment-related toxicities were recorded according to the CTCAE-5 version. The study group consisted of 106 patients. Respectively, 36% and 61% of patients had stage II and stage III upper rectal cancer. The median follow-up period was 4.4 ± 3.4 years. Five-year overall survival and progression-free survival were respectively 78% [95% confidence interval (CI)=69.2-88] and 76.8% (95%CI=68.4-86.2). The rate of local recurrence at 5 years was 3.78% (95%CI=0-7.98). Forty-two percent of patients presented early toxicities and 27.4% of patients experienced early surgical complications. Late toxicities and surgical complications occurred in 24.5% and 9.4% of patients, respectively. Neoadjuvant (chemo) radiotherapy followed by total mesorectal excision of stage II-III upper rectal cancer is effective and safe.

Doppler Lidar and Mobile Radiosonde Observation-Based Evaluation of Warn-on-Forecast System Predicted Near-Supercell Environments during TORUS 2019

Abstract Observational data collection is extremely hazardous in supercell storm environments, which makes for a scarcity of data used for evaluating the storm-scale guidance from convection allowing models (CAMs) like the National Oceanic and Atmospheric Administration (NOAA) Warn-on-Forecast System (WoFS). The Targeted Observations with UAS and Radar of Supercells (TORUS) 2019 field mission provided a rare opportunity to not only collect these observations, but to do so with advanced technology: vertically pointing Doppler lidar. One standing question for WoFS is how the system forecasts the feedback between supercells and their near-storm environment. The lidar can observe vertical profiles of wind over time, creating unique datasets to compare to WoFS kinematic predictions in rapidly evolving severe weather environments. Mobile radiosonde data are also presented to provide a thermodynamic comparison. The five lidar deployments (three of which observed tornadic supercells) analyzed show WoFS accurately predicted general kinematic trends in the inflow environment; however, the predicted feedback between the supercell and its environment, which resulted in enhanced inflow and larger storm-relative helicity (SRH), were muted relative to observations. The radiosonde observations reveal an overprediction of CAPE in WoFS forecasts, both in the near and far field, with an inverse relationship between the CAPE errors and distance from the storm. Significance Statement It is difficult to evaluate the accuracy of weather prediction model forecasts of severe thunderstorms because observations are rarely available near the storms. However, the TORUS 2019 field experiment collected multiple specialized observations in the near-storm environment of supercells, which are compared to the same near-storm environments predicted by the National Oceanic and Atmospheric Administration (NOAA) Warn-on-Forecast System (WoFS) to gauge its performance. Unique to this study is the use of mobile Doppler lidar observations in the evaluation; lidar can retrieve the horizontal winds in the few kilometers above ground on time scales of a few minutes. Using lidar and radiosonde observations in the near-storm environment of three tornadic supercells, we find that WoFS generally predicts the expected trends in the evolution of the near-storm wind profile, but the response is muted compared to observations. We also find an inverse relationship of errors in instability to distance from the storm. These results can aid model developers in refining model physics to better predict severe storms.

Total Solar Irradiance during the Last Five Centuries

The total solar irradiance (TSI) varies on timescales of minutes to centuries. On short timescales it varies due to the superposition of intensity fluctuations produced by turbulent convection and acoustic oscillations. On longer timescales, it changes due to photospheric magnetic activity, mainly because of the facular brightenings and dimmings caused by sunspots. While modern TSI variations have been monitored from space since the 1970s, TSI variations over much longer periods can only be estimated either using historical observations of magnetic features, possibly supported by flux transport models, or from the measurements of the cosmogenic isotope (e.g., 14C or 10Be) concentrations in tree rings and ice cores. The reconstruction of the TSI in the last few centuries, particularly in the 17th/18th centuries during the Maunder minimum, is of primary importance for studying climatic effects. To separate the temporal components of the irradiance variations, specifically the magnetic cycle from secular variability, we decomposed the signals associated with historical observations of magnetic features and the solar modulation potential Φ by applying an empirical mode decomposition algorithm. Thus, the reconstruction is empirical and does not require any feature contrast or field transport model. The assessed difference between the mean value during the Maunder minimum and the present value is ≃2.5 W m−2. Moreover it shows, in the first half of the last century, a growth of ≃1.5 W m−2, which stops around the middle of the century to remain constant for the next 50 years, apart from the modulation due to the solar cycle.

Imaging the Infection Cycle of T7 at the Single Virion Level.

T7 phages are E. coli-infecting viruses that find and invade their target with high specificity and efficiency. The exact molecular mechanisms of the T7 infection cycle are yet unclear. As the infection involves mechanical events, single-particle methods are to be employed to alleviate the problems of ensemble averaging. Here we used TIRF microscopy to uncover the spatial dynamics of the target recognition and binding by individual T7 phage particles. In the initial phase, T7 virions bound reversibly to the bacterial membrane via two-dimensional diffusive exploration. Stable bacteriophage anchoring was achieved by tail-fiber complex to receptor binding which could be observed in detail by atomic force microscopy (AFM) under aqueous buffer conditions. The six anchored fibers of a given T7 phage-displayed isotropic spatial orientation. The viral infection led to the onset of an irreversible structural program in the host which occurred in three distinct steps. First, bacterial cell surface roughness, as monitored by AFM, increased progressively. Second, membrane blebs formed on the minute time scale (average ~5 min) as observed by phase-contrast microscopy. Finally, the host cell was lysed in a violent and explosive process that was followed by the quick release and dispersion of the phage progeny. DNA ejection from T7 could be evoked in vitro by photothermal excitation, which revealed that genome release is mechanically controlled to prevent premature delivery of host-lysis genes. The single-particle approach employed here thus provided an unprecedented insight into the details of the complete viral cycle.

Slow spin dynamics and quantum tunneling of magnetization in the dipolar antiferromagnet DyScO3

We present a comprehensive study of static and dynamic magnetic properties in the Ising-like dipolar antiferromagnet (AFM) DyScO$_3$\ by means of DC and AC magnetization measurements supported by classical Monte-Carlo calculations. Our AC-susceptibility data show that the magnetic dynamics exhibit a clear crossover from an Arrhenius-like regime to quantum tunneling of magnetization (QTM) at $T^* = 10$ K. Below $T_{\mathrm{N}} = 3.2$ K DyScO$_3$ orders in an antiferromagnetic $GxAy$-type magnetic structure and the magnetization dynamics slow down to the minute timescale. The low-temperature magnetization curves exhibit complex hysteretic behavior, which depends strongly on the magnetic field sweep rate. We demonstrate that the low-field anomalies on the magnetization curve are related to the metamagnetic transition, while the hysteresis at higher fields is induced by a strong magnetocaloric effect. Our theoretical calculations, which take into account dipolar interaction between Dy$^{3+}$ moments, reproduce essential features of the magnetic behavior of DyScO$_3$. We demonstrate that DyScO$_3$ represents a rare example of inorganic compound, which exhibits QTM at a single-ion level and magnetic order due to classical dipolar interaction.

A flexible electronic strain sensor for the real-time monitoring of tumor regression.

Assessing the efficacy of cancer therapeutics in mouse models is a critical step in treatment development. However, low-resolution measurement tools and small sample sizes make determining drug efficacy in vivo a difficult and time-intensive task. Here, we present a commercially scalable wearable electronic strain sensor that automates the in vivo testing of cancer therapeutics by continuously monitoring the micrometer-scale progression or regression of subcutaneously implanted tumors at the minute time scale. In two in vivo cancer mouse models, our sensor discerned differences in tumor volume dynamics between drug- and vehicle-treated tumors within 5 hours following therapy initiation. These short-term regression measurements were validated through histology, and caliper and bioluminescence measurements taken over weeklong treatment periods demonstrated the correlation with longer-term treatment response. We anticipate that real-time tumor regression datasets could help expedite and automate the process of screening cancer therapies in vivo.

A novel model for water quality prediction caused by non-point sources pollution based on deep learning and feature extraction methods

• The established model could reflect the impact of non-point source pollution on water quality. • The hybrid model performed very well in the water quality prediction. • The hybrid model improved the accuracy of extreme water quality prediction. Non-point source (NPS) pollution is an important factor affecting the quality of water environment. In recent years, a large number of online water quality monitoring stations have been used to obtain continuous time series water quality monitoring data. These data provide the necessary basis for the application of deep learning methods in water quality prediction. However, the prediction accuracy of traditional deep learning methods is low, especially in predicting the water quality with NPS pollution. Aiming to address this limitation, a novel deep learning model named SOD-VGG-LSTM with the simulation-observation difference (SOD) modular based on physical process, the visual geometry (VGG) modular reflecting spatial characteristics, and the long short-term memory (LSTM) modular based on deep learning method was developed to improve the accuracy of the water quality prediction with NPS pollution. The established model can overcome the problem that mechanism models can not predict the changes of water quality on the hourly or minute time scale. The model was applied in Lijiang River watershed. Experimental results indicated that the proposed model had the highest accuracy in the extreme value prediction compared with the mechanism model and LSTM model. The maximum relative errors between the predicted and observed results for DO, COD Mn , NH 3 -N, and TP were 8.47%, 19.76%, 24.1%, and 35.4%, respectively. The model evaluation demonstrated that the established SOD-VGG-LSTM model achieved superior computational performance compared to Auto Regression Integreate Moving Average model (ARIMA), Support Vector Regression model (SVR), and Recurrent Neural Network model (RNN). The evaluation results showed that SOD-VGG-LSTM achieved 3.2–39.3% higher R 2 than ARIMA, SVR and RNN. The proposed model can provide a new method for water quality prediction with NPS pollution.

Multi-timescale and control-perceptive scheduling approach for flexible operation of power plant-carbon capture system

A carbon-capture system is required for coal-fired power plants to meet environmental regulation and provide support for grid penetration of renewable energy sources, when the integrated power plant-carbon capture system must operate in a highly flexible manner to accommodate the need for intermittent renewable power. To this end, this paper proposes a hierarchical scheduling scheme for the operation of integrated power plant-carbon capture system to fully exploit the decarbonization and flexibility of carbon capture technology in multiple timescales. The upper layer of the hierarchy implements a day-ahead stochastic scheduling to provide hourly operating instructions in the next 24 h so that the overall economic performance of the plant can be best achieved, including fuel consumption, load following and carbon trading. A novel index is then introduced to reflect the power adjustment contribution of carbon capture in the intraday scheduling layer and enhance the load ramping performance of power plant by flexible operation of the post-combustion carbon capture in minute timescale. In the lower layer of the hierarchy, control-perceptive scheduling based on close-loop dynamic model is proposed to coordinate the scheduling and underlying control, making the scheduling feasible for the operating practice. In addition, a new control system, which uses the reboiler steam flowrate to control the CO2 production rate and solvent circulation flowrate to control reboiler temperature is proposed to achieve superior flexibility support role of carbon capture. The case study shows that the proposed scheduling approach can improve the load tracking performance by 36.7% with satisfactory performance in carbon capture, which verifies the efficacy of the proposed scheduling approach in the power system. The impact of the proposed control system is also investigated, providing a broad insight on the flexible operation of carbon capture technology integrated with the power plant.

Persistence of Monoterpene-Derived Organic Peroxides in the Atmospheric Aqueous Phase

Organic peroxides are essential reactive species formed during the atmospheric oxidation of organic compounds and can effectively partition into aqueous aerosols and cloud droplets, yet their aqueous-phase fate in aerosol and cloud water remains poorly characterized. Here, we report the first investigation of the isomer-resolved aqueous-phase chemical behaviors of a large suite of organic peroxides in dissolved monoterpene secondary organic aerosol (SOA). We find that about half of individual peroxides undergo noticeable hydrolysis, while the other half mainly react via nonhydrolysis unimolecular or bimolecular pathways. The chemical complexity of organic peroxides, as well as the effects of coexisting organic compounds in dissolved SOA, results in diverse chemical behaviors of individual peroxides and a complicated dependence on the water content, pH, and even organic concentration in the aqueous phase. Compared to the previously investigated α-substituted hydroperoxides that undergo hydrolysis on timescales of minutes to a few hours, the vast majority of organic peroxides studied herein are significantly more persistent in the aqueous phase, with decay rate constants of 1.8 × 10–6 to 2.4 × 10–4 s–1 and the corresponding e-folding lifetimes of 1.1–153 h under atmospherically relevant conditions, which would have distinctly different impacts on atmospheric chemistry and human health.

Characterization and classification of estuarine suspended particles based on their inorganic/organic matter composition

An 11 hours survey was performed on the 17th of September 2014 in the Rhine Region Of Freshwater Influence (Rhine-ROFI) about 10 km downstream of the mouth of the Rotterdam Waterway during calm weather conditions. Suspended Particle Matter (SPM) measurements were performed during a full tidal cycle, near the seabed, at neap tide, and samples were taken at 0.6 meter above bed for on-board analysis. The measurements were performed with (a) LISST 100X, a submersible particle size analyzer, (b) LISST-HOLO, a submersible digital holographic camera, (c) a home-made underwater camera and (d) an on-board LabSFLOC2 video microscopy equipment that used in-situ collected samples. The first aim of the present study was to compare the results obtained from the different monitoring techniques and to characterize the different types of suspended particles found in-situ. It was found that that the highly anisotropic particles present in the water column lead to multiple peaks in the Particle Size Distributions (PSD) found using the LISST 100X. Using the LISST-HOLO, underwater camera and LabSFLOC2 camera these particles could properly be imaged and meaningful PSD’s were obtained using these techniques in the size range > 20 μm. LabSFLOC2, LISST-HOLO and the underwater camera moreover provide information on the size and aspect ratio of particles. On the other hand, LISST 100X can be used to detect the fine fraction (<20 μm), a size range that is not accessible for the other techniques. From the analysis of the data on the survey day, three classes of particles were identified, based on composition rather than size (the sizes given here are purely indicative): (1) mineral (inorganic) sediment particles in the range size 5 - 20 μm, (2) organic/inorganic aggregates in the size range 20 - 200 μm and (3) organic particles in the size range > 200 μm. A large range of settling velocities (0.1 - 10 mm/s) and aspect ratios between 1 and 10 were recorded by video microscopy (LabSFLOC2). This spreading in settling velocities and aspect ratio was due to the different properties (shape, effective density and size) of the particles in the water column. The second aim of the study was to reproduce the flocs found in-situ in the lab and investigate the kinetics of flocculation between inorganic and living organic matter. Laboratory experiments were conducted with grab samples obtained from Port of Rotterdam harbour and living microalgae (Skeletonema costatum). The results of these experiments showed a shift in effective density upon addition of living algae to the sediment, which confirmed the flocculation ability between sediment and microalgae. The flocculation occured on a timescale of minutes and lead to flocs having a large spread in density for a given size, due to the heteregeous inorganic/organic composition of the flocs. This spread in density was at the origin of the large range of settling velocities for a given floc size observed in-situ, which leads to conclude that organic matter should be an important input parameter in sediment transport models.

Determination of In Vitro and Cellular Turn-on Kinetics for Fluorogenic RNA Aptamers.

Fluorogenic RNA aptamers have been applied in live cells to tag and visualize RNAs, report on gene expression, and activate fluorescent biosensors that detect levels of metabolites and signaling molecules. In order to study dynamic changes in each of these systems, it is desirable to obtain real-time measurements, but the accuracy of the measurements depends on the kinetics of the fluorogenic reaction being faster than the sampling frequency. Here, we describe methods to determine the in vitro and cellular turn-on kinetics for fluorogenic RNA aptamers using a plate reader equipped with a sample injector and a flow cytometer, respectively. We show that the in vitro kinetics for the fluorescence activation of the Spinach2 and Broccoli aptamers can be modeled as two-phase association reactions and have differing fast phase rate constants of 0.56 s-1 and 0.35 s-1, respectively. In addition, we show that the cellular kinetics for the fluorescence activation of Spinach2 in Escherichia coli, which is further limited by dye diffusion into the Gram-negative bacteria, is still sufficiently rapid to enable accurate sampling frequency on the minute timescale. These methods to analyze fluorescence activation kinetics are applicable to other fluorogenic RNA aptamers that have been developed.

Functional inference of gene regulation using single-cell multi-omics

SUMMARYCells require coordinated control over gene expression when responding to environmental stimuli. Here we apply scATAC-seq and single-cell RNA sequencing (scRNA-seq) in resting and stimulated human blood cells. Collectively, we generate ~91,000 single-cell profiles, allowing us to probe the cis-regulatory landscape of the immunological response across cell types, stimuli, and time. Advancing tools to integrate multi-omics data, we develop functional inference of gene regulation (FigR), a framework to computationally pair scA-TAC-seq with scRNA-seq cells, connect distal cis-regulatory elements to genes, and infer gene-regulatory networks (GRNs) to identify candidate transcription factor (TF) regulators. Utilizing these paired multi-omics data, we define domains of regulatory chromatin (DORCs) of immune stimulation and find that cells alter chromatin accessibility and gene expression at timescales of minutes. Construction of the stimulation GRN elucidates TF activity at disease-associated DORCs. Overall, FigR enables elucidation of regulatory interactions across single-cell data, providing new opportunities to understand the function of cells within tissues.

Variations in Observations of Geosynchronous Magnetopause and Last Closed Drift Shell Crossings With Magnetic Local Time

AbstractWe analyze a set of events in which both electron flux dropouts caused by magnetopause shadowing and geosynchronous magnetopause crossings (GMCs) are observed. These observations are compared to event‐specific last closed drift shell (LCDS) models derived from the TS05 and TS07 external field models and magnetopause standoff distance. The LCDS models show good association with losses due to magnetopause shadowing but fail to reproduce observations of GMCs on the timescale of minutes. We show that different satellites in geostationary orbit observe different trends in electron flux during storm events on timescales of less than a day due to their separation in longitude. These differences demonstrate that both satellite L* and magnetic local time must be taken into account when modeling rapid variations in the outer radiation belt, and at least three satellites in geostationary orbit, ideally more, may be required for accurate forecasting and reconstruction of these events on timescales shorter than days.

Ash and gas discharge during open vent activity at El Reventador (Ecuador): explosion-style transitions driven by conduit capping

Since the VEI 4 eruption of November 2002, El Reventador volcano (Ecuador) has been the site of persistent open-vent activity characterized by frequent (hourly) Vulcanian—strombolian explosions and occasional (every few years) effusion of lava flows. The conduit processes that sustain this continuous eruptive activity are still poorly understood. Here, we combine high temporal resolution thermal infrared imaging with seismic recordings and DOAS-derived SO2 fluxes focusing on a period of Vulcanian-style activity on 22–23 February 2017. Thermal imagery captured the emission and ascent dynamics of 26 plumes during the observation period, including those fed by explosions and degassing episodes. While most explosions have associated seismic signals, a few are marked by the absence of measurable seismic activity. Degassing episodes also show very few associated seismic signals. Explosions and degassing events seem to follow a sequence that can be explained by changes in the conduit permeability associated with rapid (over time scales of minutes) rheological stiffening of magma in the uppermost portion of the conduit to reduce degassing efficiency. Periods of open-vent outgassing alternate with periods of conduit capping resulting in system pressurization and leading to Vulcanian explosions that re-open the conduit allowing outgassing to resume.

How does a resilient, flexible ammonia process look? Robust design optimization of a Haber-Bosch process with optimal dynamic control powered by wind

Ammonia can be an essential energy vector for storing excess renewable energy during the year and release this energy when demand is high. This storage during the year provides an essential part in the energy sector for moments when there is not enough wind and sun to cover the demand. Although the Haber-Bosch is a very mature process to synthesize hydrogen and nitrogen to ammonia, it is not flexible enough to match the erratic nature of renewables. This mismatch creates the need for large intermediate hydrogen buffer tanks. To reduce the capacity of the hydrogen storage tank, we need to optimize the dynamic power-to-ammonia process in a minute time scale while considering the uncertainties linked to renewables. Therefore, we coupled a stochastic wind power process to a dynamic Power-to-Ammonia process and performed a design optimization under uncertainties, i.e. a robust design optimization, for a three-hour wind scenario while considering optimal dynamic control. The robust design optimization showed significant trade-offs between the most productive, the most flexible, the most resilient, and robust power-to-ammonia plant designs. For the flexible and productive designs, the bypass fraction and buffer feed have essential roles in achieving these designs. In the future, we will use a stochastic process to consider the uncertainty of renewable power over more extended periods (days, weeks and months) coupled with the robust design optimization of the dynamic power-to-ammonia process and investigate its effect on the intermediate hydrogen buffer size and the plant’s cost.

Multi-Stream Perfusion Bioreactor Integrated with Outlet Fractionation for Dynamic Cell Culture.

Certain cell and tissue functions operate within the dynamic time scale of minutes to hours that are poorly resolved by conventional culture systems. This work has developed a low-cost perfusion bioreactor system that allows culture medium to be continuously perfused into a cell culture module and fractionated in a downstream module to measure dynamics on this scale. The system is constructed almost entirely from commercially available parts and can be parallelized to conduct independent experiments in conventional multi-well cell culture plates simultaneously. This video article demonstrates how to assemble the base setup, which requires only a single multichannel syringe pump and a modified fraction collector to perfuse up to six cultures in parallel. Useful variants on the modular design are also presented that allow for controlled stimulation dynamics, such as solute pulses or pharmacokinetic-like profiles. Importantly, as solute signals travel through the system, they are distorted due to solute dispersion. Furthermore, a method for measuring the residence time distributions (RTDs) of the components of the perfusion setup with a tracer using MATLAB is described. RTDs are useful to calculate how solute signals are distorted by the flow in the multi-compartment system. This system is highly robust and reproducible, so basic researchers can easily adopt it without the need for specialized fabrication facilities.