Color Tracers Research Articles

Facilitated Transport across Glycocalyceal Barriers in the Chick Chorioallantoic Membrane.

Targeted drug delivery to visceral organs offers the possibility of not only limiting the required dose, but also minimizing drug toxicity; however, there is no reliable method for delivering drugs to the surface of visceral organs. Here, we used six color tracers and the chick chorioallantoic membrane (CAM) model to investigate the use of the heteropolysaccharide pectin to facilitate tracer diffusion across the glycocalyceal charge barrier. The color tracers included brilliant blue, Congo red, crystal violet, indocyanine green, methylene blue, and methyl green. The direct application of the tracers to the CAM surface or embedding tracers into linear-chain nanocellulose fiber films resulted in no significant diffusion into the CAM. In contrast, when the tracers were actively loaded into branched-chain pectin films, there was significant detectable diffusion of the tracers into the CAM. The facilitated diffusion was observed in the three cationic tracers but was limited in the three anionic tracers. Diffusion appeared to be dependent on ionic charge, but independent of tracer size or molecular mass. We conclude that dye-loaded pectin films facilitated the diffusion of color tracers across the glycocalyceal charge barrier and may provide a therapeutic path for drug delivery to the surface of visceral organs.

Determination of sediment sources following a major wildfire and evaluation of the use of color properties and polycyclic aromatic hydrocarbons (PAHs) as tracers

PurposeThis research aimed to determine if a severe wildfire caused changes in the source of sediment being delivered to downstream aquatic systems and evaluate the use of polycyclic aromatic hydrocarbons (PAHs) and color properties as tracers.MethodsSediment samples were collected from 2018 to 2021 in three tributaries impacted by the 2018 Shovel Lake wildfire and from two sites on the mainstem of the Nechako River, British Columbia. Source samples were collected from burned and unburned soils as well as from channel banks and road-deposited sediment. Samples were analyzed for color properties and for the 16 US Environmental Protection Agency priority PAHs. After statistical tests to determine the conservatism and ability to discriminate between sources by the tracers, the MixSIAR unmixing model was used, and its outputs were tested using virtual mixtures.ResultIn the tributaries, burned topsoil was an important contributor to sediment (up to 50%). The mainstem Nechako River was not influenced as significantly by the fires as the greatest contributor was banks (up to 89%). The color properties provided more realistic results than those based on PAHs.ConclusionIn smaller watersheds, the wildfire had a noticeable impact on sediment sources, though the impacts of the fire seemed to be diluted in the distal mainstem Nechako River. Color tracers behaved conservatively and discriminated between contrasting sources. Due to their low cost and reliability, they should be considered more widely. While PAHs did not work in this study, there are reasons to believe they could be a useful tracer, but more needs to be understood about their behavior and degradation over time.

New Approach to Generate Ratiometric Signals on Immunochromatographic Strips for Small Molecules.

The self-calibration capability of ratiometric signals has been widely considered to enhance the accuracy, sensitivity, and anti-interference ability of immunoassays. Exploring a new approach to generate ratiometric signals can provide more options for various requirements. Herein, we integrated the negative-readout competitive and positive-readout noncompetitive immunoassays into a single assay by employing different color tracers, labeled peptidomimetic and anti-immunocomplex peptides, to create a new unconstrained ratiometric signal approach. Using an immunochromatographic strip (ICS) and a fungicide benzothiostrobin as the analytical platform and analyte, respectively, we showed that this approach can be extensively applied to fluorescence and colorimetry readouts, which have also been proven for strong anti-interference ability to an external light environment. Moreover, the enormous intuitional color changes of ratiometric fluorescent and colorimetric ICSs (RFICS and RCICS) enabled the formation of the color reference cards (like the pH paper) for visual judgment. After adaptation with a portable smartphone, the quantitative detection limits for RFICS and RCICS were 0.17 and 0.44 ng mL-1, respectively. In addition, the ICSs showed good accuracy for the detection of benzothiostrobin in spiked samples.

Comparing alternative tracing measurements and mixing models to fingerprint suspended sediment sources in a mesoscale Mediterranean catchment

Knowledge of suspended sediment provenance in mesoscale catchments is important for applying erosion control measures and best management practices as well as for understanding the processes controlling sediment transport in the critical zone. As suspended sediment fluxes are highly variable in time, particularly given the variability of soil and rainfall properties in mesoscale catchments, knowledge of sediment provenance at high temporal resolution is crucial. Suspended sediment fluxes were analyzed at the outlet of a 42-km2 Mediterranean catchment belonging to the French critical zone observatory network (OZCAR). Spatial origins of the suspended sediments were analyzed at high temporal resolution using low-cost analytical approaches (color tracers, X-ray fluorescence, and magnetic susceptibility). As the measurements of magnetic susceptibility provide only one variable, they were used for cross-validation of the results obtained with the two alternative tracing methods. The comparison of the tracer sets and three mixing models (non-negative least squares, Bayesian mixing model SIMMR, and partial least squares regression) allowed us to estimate different sources of errors inherent in sediment fingerprinting studies and to assess the challenges and opportunities of using these fingerprinting methods. All tracer sets and mixing models could identify marly badlands as the main source of suspended sediments. However, the percentage of source contributions varied between the 11 flood events in the catchment. The mean contribution of the badlands varied between 74 and 84%; the topsoils on sedimentary geology ranged from 12 to 29% and the basaltic topsoils from 1 to 8%. While for some events the contribution remained constant, others showed a high within-event variability of the sediment provenance. Considerable differences in the predicted contributions were observed when different tracer sets (mean RMSE 19.9%) or mixing models (mean RMSE 10.1%) were used. Our result shows that the choice of the tracer set was more important than the choice of the mixing model. These results highlighted the importance of using multi-tracer multi-model approaches for sediment fingerprinting in order to obtain reliable estimates of source contributions. As a given fingerprinting approach might be more sensitive to one type of error, i.e., source variability, particle size selectivity, multi-tracer ensemble predictions allow to detect and quantify these potential biases. High sampling resolution realized with low-cost methods is important to reveal within- and between-event dynamics of sediment fluxes and to obtain reliable information of main contributing sources.

RTD modeling of a continuous dry granulation process for process control and materials diversion

Disturbance propagation during continuous manufacturing processes can be predicted by evaluating the residence time distribution (RTD) of the specific unit operations. In this work, a dry granulation process was modelled and four scenarios of feeding events were simulated. We performed characterization of the feeders and developed RTD models for the blender and the roller compactor based on impulse-response measurements via color tracers. Out-of-specification material was defined based on the active pharmaceutical ingredient (API) concentration. We calculated the amount of waste material at various diversion points, considering four feeder-related process-upset scenarios and formulated considerations for the development of a control concept. The developed RTD models allow material tracking of materials that may be used for following the spread contaminants within the process and for batch definition. The results show that RTD modeling is a valuable tool for process development and design, as well as for process monitoring and material tracking.

Alteration ofChironomus plumosusventilation activity and bioirrigation-mediated benthic fluxes by changes in temperature, oxygen concentration, and seasonal variations

Abstract. Burrowing benthic organisms promote water and solute fluxes across the sediment–water interface. Water and solutes penetrate the burrow walls and are transported into/out of the sediment when organisms flush their burrows with overlying water. Few studies have been done to investigate bioirrigation under shifting environmental conditions. We experimentally quantified bioirrigation by Chironomus plumosus larvae in the laboratory at 3 ranges of O2 saturation (low, medium, and high O2 concentrations), 2 temperatures (10 and 20°C), and over different seasons. We measured ventilation activities with O2 and flow-velocity microsensors, flow velocities during pumping periods with color tracers, pumping rates with conductivity exchange experiments, and rates of advective and diffusive water influx into the sediment by influx assays (NaCl was the tracer in both latter experiments). O2 saturations <12% extended pumping durations/h, whereas saturations <3% decreased pumping durations to ∼0. Flow velocities...

Non-invasive in situ concentration determination of fluorescent or color tracers and pollutants in a glass pore network model

This study presents a non-invasive imaging method for in situ concentration determination of conservative tracers and pollutants in a two-dimensional glass pore network model. The method presented is an extension to the work by Huang et al. [1], and Thomas and Chysikopoulos [2]. The method consists of fabricating the glass pore network model using a photolithography technique, conducting flowthrough contaminant transport experiments, taking digital photographs at various times of the two-dimensional pore network under ultraviolet or visible light source, and determining the spatially-distributed pollutant concentrations by measuring the color intensity in the photographs with comparative image analysis. Therefore, the method is limited to fluorescent or colored pollutants and tracers. The method was successfully employed to in situ concentration determination of uranine and red color tracers.

Study on spliced yarns of different spinning technologies. Part I: tensile characteristics

The details of a study on splicing behavior of viscose staple fiber yarns, prepared by ring, rotor, and air-jet spinning technologies, are reported in this paper. All the yarns had six different color tracers with each having 0.3% of total fibers. The mechanical and structural properties of splices were studied. A three-variable three-level factorial design approach proposed by Box and Behnken was used to study the interactive effect of splicing parameters. The splicing parameters such as splicing length, duration of splicing air blast, and splicing air pressure were varied to prepare spliced yarn samples. Splices were introduced at all these levels for the three different technologies. The present paper (Part I) deals with the mechanical characteristics of splice portions, i.e. retained splice strength (RSS) and retained splice elongation (RSE). It has been observed that there are significant effects of all these parameters on the tensile characteristics of spliced yarns. However, the trends are different for different spinning technologies. Part II of this paper deals with the internal structural characteristics of splices.

Study on spliced yarns of different spinning technologies. Part II: structural characteristics

A detailed study on structural parameters of splices of viscose staple fiber yarns made from ring, rotor, and air-jet spinning technologies are reported in this paper. All the yarns each had six different color tracers with 0.3% of total fibers. A three variable three-level factorial design approach proposed by Box and Behnken has been used to study the interactive effect of splicing parameters. The splicing parameters, such as splicing length, duration of splicing air blast, and splicing air pressure were varied to prepared spliced yarn samples. Splices were introduced at all these levels for the three different technologies. This paper deals with the structural characteristics of splice portions, i.e. splice diameter, helix angle, splicing coefficient of fiber (SCF), and fiber overlapping coefficient (FOC). The structural characteristics, such as splice diameter, helix angle, SCF, and FOC, are significantly affected by the different splicing parameters (i.e. splice length, duration of the opening air blast, and splicing air pressure). Different types of yarns (ring-, rotor-, and air-jet-spun) show different trends of structural characteristics with splicing parameters. Part I of this paper deals with the mechanical characteristics of spliced portion.

Bioirrigation byChironomus plumosus: advective flow investigated by particle image velocimetry

AbstractBioirrigation by tube-dwelling macrozoobenthos species causes an advective flow of overlying water through the burrow lumen. Particle image velocimetry (PIV) and color tracer measurements were used to measure flow velocities. The volumetric flow rate was calculated based on measured velocities and visual observation of larval body movements. Investigations were done with Chironomus plumosus (Diptera:Chironomidae) larvae and pupae. During pumping periods, flow velocity was 15.0 ± 10.7 (with color tracers: 13.6 ± 1.7) mm/s and volumetric flow rate was 40 ± 24 (with color tracers: 30.9 ± 3.9) µL/s for larvae. For pupae, these values were only 5.1 ± 0.7 mm/s and 11 ± 1 µL/s, respectively. Pupae conduct no filter feeding, so our results indicate that high volumetric flow rates occur because of filter-feeding. Furthermore, PIV measurements revealed the filtering effect of C. plumosus bioirrigation activity. A projection of the measured volumetric flow rate to Lake Muggelsee in Berlin, Germany (745 4th-i...

Distribution of carbon isotopes in the glacial ocean: A model study

A series of simulations are conducted with a global climate model of intermediate complexity (MoBidiC). This model includes ocean circulation dynamics, including the carbon cycle, coupled to a zonally averaged atmosphere. Oceanic distributions of nutrients, apparent oxygen utilization, radiocarbon, and carbon 13 are discussed for the preindustrial era (validation) as well as three states of the glacial ocean, termed interstadial (very active formation of deep water in the North Atlantic Ocean), stadial (moderate convection and important flow of Antarctic Deep Water in the Atlantic), and Heinrich (no formation of North Atlantic Deep Water). The stadial and interstadial states are stable. The Heinrich state is forced by a continuous freshwater discharge into the North Atlantic. The model exhibits significant changes in the isotopic composition of the ocean between the three modeled glacial states. Results for δ13C tend to be in qualitative agreement with paleoceanographic data, except that the model fails at representing the strong depletion in δ13C in the Southern Ocean. The Heinrich Atlantic Ocean is older than the stadial ocean at all depths (up to 1500 years). The “interstadial” ocean has younger deep water and older intermediate water than the “stadial.” It is recognized that the simulated changes in intermediate water age are less reliable because of the structure of the model. Color tracers are used to show that changes in the isotopic composition of Atlantic bottom water are mainly related to a redistribution of water masses. A simple method is tested, by which it is possible to reconstruct the North Atlantic water flow from the zonal profiles of salinity and Δ14C. Finally, dividing artificially the gas exchange rate in the Southern Ocean by four results in a 0.4‰ decrease in the δ13C of Antarctic Bottom Water. Changes in new production are, comparatively, less effective at altering the δ13C ratio.

Topological relation of chick thalamofugal visual projections with hyper pallium revealed by three color tracers

In birds, there are two visual projections from retina to higher pallium, i.e., tectofugal and thalamofugal pathways. The latter one is lateralized in chick and suggested to be involved in visually evoked social behavior, like recognition of novelty, predator, and conspecific animals. We wanted to establish functionally relevant topological connection map between thalamic nuclei and hyperpallium apicale (HA) and carried out tracing study with three color fluorescent tracers. The tracers were serially injected in HA either along with the medial–lateral (M–L) or anterior–posterior (A–P) axis. We found that M–L axis and A–P axis in HA were transferred into the dorsal–ventral axis and the medial–lateral axis, respectively within the nucleus geniculatus lateralis pars dorsalis (GLd). In another word, the medial part of nucleus dorsolateralis anterior thalami pars lateralis (DLLv) projected to anterior part of HA and the ventral part of nucleus dorsolateralis anterior thalami pars lateralis pas ventralis (DLLd) projects to lateral HA. This result suggests that thalamus would process information in parallel through each subnuclei and elaborate coordination among them in relation to topological map presented in higher pallium.

Photochromic Flow Visualization for the Investigation of Artificial Heart Valves

A new method for the investigation of hydrodynamics of artificial heart valves is presented. It is a method of flow visualisation. The photochromic flow visualization method is based on activation of color tracers in originally colorless photochromic solutions by pulse laser radiation during 10(-6)-10(-9) seconds. The tracer appears as a straight colored line, which subsequently is deformed by the flow. The methods known so far for the flow visualization give an insight on the general flow but do not provide quantitative data. The method mainly used, the LDA, permits measurements only in one point. The new method combines the precision of the LDA with the clarity of flow visualization.