Dispersal Paths Research Articles

Occurrence of radioactive cesium-rich micro-particles (CsMPs) in a school building located 2.8 km south-west of the Fukushima Daiichi Nuclear Power Plant

Radioactive Cs-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) are a potential health risk through inhalation. Little has been documented on the occurrence of CsMPs, particularly their occurrence inside buildings. In this study, we quantitatively analyze the distribution and number of CsMPs in indoor dust samples collected from an elementary school located 2.8 km to the southwest of FDNPP. The school had remained deserted until 2016. Then, using a modified version of the autoradiography-based “quantifying CsMPs (mQCP) method,” we collected samples and determined the number of CsMPs and Cs radioactive fraction (RF) values of the microparticles (defined as total Cs activity from CsMPs/bulk Cs activity of the entire sample). The numbers of CsMPs ranged from 653 to 2570 particles/(g dust) and 296–1273 particles/(g dust) on the first and second floors of the school, respectively. The corresponding RFs ranged between 6.85 – 38.9% and 4.48–6.61%, respectively. The number of CsMPs and RF values in additional outdoor samples collected near the school building were 23–63 particles/(g dust or soil) and 1.14–1.61%, respectively. The CsMPs were most abundant on the school's first floor near to the entrance, and the relative abundance was higher near the stairs on the second floor, indicating a likely CsMP dispersion path through the building. Additional wetting of the indoor samples combined with autoradiography revealed that indoor dusts had a distinct absence of intrinsic, soluble Cs species, such as CsOH. These combined observations indicate that a significant amount of poorly soluble CsMPs were likely contained in initial radioactive airmass plumes from the FDNPP and that the microparticles penetrated buildings. CsMPs could still be abundant at the location, with locally high Cs activity in indoor environments near to openings.

Prediction of COVID-19 infection in dental clinic by CFD and Wells-Riley model, identifying safe area and proper ventilation velocity

The COVID-19 virus is recognized worldwide as a significant public health threat. A dental clinic is one of the most dangerous places in the COVID-19 epidemic, and disease transmission is rapid. Planning is essential to create the right conditions in the dental clinic. In this study, the cough of an infected person is examined in a 9 × 6 × 3 m3 area. Computational fluid dynamic (CFD) is applied to simulate the flow field and to determine the dispersion path. The innovation of this research is checking the risk of infection for each person in the designated dental clinic, choosing the suitable velocity for ventilation, and identifying safe areas. In the first step, the effects of different ventilation velocities on the dispersion of virus-infected droplets are investigated, and the most appropriate ventilation flow velocity has been identified. Then, the results of the presence or absence of a dental clinic separator shield on the spread of respiratory droplets have been identified. Finally, the risk of infection (by the Wells-Riley equation) is assessed, and safe areas are identified. The effect of RH on droplet evaporation in this dental clinic is assumed to be 50%. The NTn values in an area with a separator shield are less than 1%. When there is a separator shield, the infection risk of people in A3 and A7 (the other side of the separator shield) is reduced from 23% to 4%, and 21% to 2%, respectively.

Low frequency lattice mode dynamics of cyclotrimethylene trinitramine (RDX) crystal studied by femtosecond time-resolved impulsive stimulated Raman scattering

The femtosecond time-resolved impulsive stimulated Raman scattering (fs-ISRS) has been performed to study the low frequency lattice mode dynamics of the RDX crystal. Through Fourier filtering, four lattice mode dynamics is distinguished from the time-resolved spectrum. And the wavenumbers and time constants of these four lattice modes are determined by fitting their dynamic curves. The energy dispersion paths of these four lattice modes are deduced from these fitting parameters. Compared with the other three lattice modes, the lattice mode with wavenumber 30 cm−1 has a very longer life time. We consider that the excitation of this lattice mode more likely to cause the damage of the intermolecular interaction under the strong external stimulation.

Subsurface dispersion path and travel time of radiocesium from Fukushima by Mode Water

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 resulted in the release of immense amounts of radioactive materials into the ocean. However, the dispersion of radioactive materials in the subsurface has not yet been clarified due to the spatiotemporal limitation of observations. Thus, herein, a tracer experiment was implemented using a three-dimensional numerical model to estimate the dispersion path of 137Cs released directly from the FDNPP and its travel time in the subsurface of the North Pacific Ocean from 2011 to 2020. The results show that the subsurface 137Cs spreads by two mode waters, namely, Sub-Tropical Mode Water (STMW) and Central Mode Water (CMW). Subsurface 137Cs primarily spreads clockwise in the sub-tropical region, while a portion driven by STMW is dispersed southward. The clockwise dispersion path of 137Cs released into the ocean by STMW is relatively shallower and inward than that by CMW. The 137Cs that was spread clockwise reached the east of Taiwan and the Philippines via STMW and CMW nine years after the accident, respectively. The model described in this study is applicable for estimating the water path and travel time of tritium water planned to be discharged from Fukushima.

Validating graph-based connectivity models with independent presence-absence and genetic data sets.

Habitat connectivity is a key objective of current conservation policies and is commonly modeled by landscape graphs (i.e., sets of habitat patches [nodes] connected by potential dispersal paths [links]). These graphs are often built based on expert opinion or species distribution models (SDMs) and therefore lack empirical validation from data more closely reflecting functional connectivity. Accordingly, we tested whether landscape graphs reflect how habitat connectivity influences gene flow, which is one of the main ecoevolutionary processes. To that purpose, we modeled the habitat network of a forest bird (plumbeous warbler [Setophaga plumbea]) on Guadeloupe with graphs based on expert opinion, Jacobs' specialization indices, and an SDM. We used genetic data (712 birds from 27 populations) to compute local genetic indices and pairwise genetic distances. Finally, we assessed the relationships between genetic distances or indices and cost distances or connectivity metrics with maximum-likelihood population-effects distance models and Spearman correlations between metrics. Overall, the landscape graphs reliably reflected the influence of connectivity on population genetic structure; validation R2 was up to 0.30 and correlation coefficients were up to 0.71. Yet, the relationship among graph ecological relevance, data requirements, and construction and analysis methods was not straightforward because the graph based on the most complex construction method (species distribution modeling) sometimes had less ecological relevance than the others. Cross-validation methods and sensitivity analyzes allowed us to make the advantages and limitations of each construction method spatially explicit. We confirmed the relevance of landscape graphs for conservation modeling but recommend a case-specific consideration of the cost-effectiveness of their construction methods. We hope the replication of independent validation approaches across species and landscapes will strengthen the ecological relevance of connectivity models.

The importance of the Andes in the evolutionary radiation of Sigmodontinae (Rodentia, Cricetidae), the most diverse group of mammals in the Neotropics

The Andean mountains stand out for their striking species richness and endemicity that characterize many emblematic Neotropical clades distributed in or around these mountains. The radiation of the Sigmodontinae subfamily, the most diversified mammalian group in the Neotropics, has been historically related to Andean orogenesis. We aim to evaluate this interplay between geological processes and biological responses through the diversification dynamics, the biogeographical history, and the range evolution of the subfamily. For these, we built the most comprehensive phylogeny and gathered 14,836 occurrences for the subfamily. We identified one shift in the speciation rate in the genus Akodon, which suffered their Andean radiation after the arrival of non-Andean ancestors. Our biogeographic analyses show multiple dispersal paths throughout the evolution that allowed this subfamily to colonize all Neotropics. The Northern Andes and Central-Southern Andes were the most important sources of diversity. In addition, the Central-Southern Andes were the most relevant sink, receiving the highest number of lineages. The Andean region exhibited higher speciation and turnover rates than non-Andean regions. Thus, our results support the crucial role of the Andean Mountains in the Sigmodontinae radiation, acting as a "macroevolutionary cradle" and "species attractor" for several sigmodontine lineages at different times, and as a "species pump" becoming the biogeographic source of multiple widely distributed neotropical lineages. Then, complex macroevolutionary dynamics would explain these rodents' high extant Andean diversity and their wide distribution in the Neotropics.

A facile synthesis of CuZrO2 nanoparticle functionalized chitosan for capable and stable non-enzymatic electrochemical detection of glucose and H2O2

Mixed transition metal oxides and organic polymers are receiving a lot of interest because of their positive characteristics, such as high permeability, large specific surface area, and ion dispersion paths.

Deep Learning-Based Miniaturized All-Dielectric Ultracompact Film Spectrometer

Conventional benchtop spectrometers with bulky dispersive optics and long optical path lengths display limitations where the significance of miniaturization, real-time detection, and low cost transcend the ultrafine resolution and wide spectral range. Here, we demonstrate a miniaturized all-dielectric ultracompact film spectrometer based on deep learning working in the single-shot mode. The scheme employs 16 spectral encoders with simple five-layer film stacks where merely the thickness of the intermediate high-index modulation layer is varied to realize unique encoded transmission spectra. Structural parameters as well as transmission spectra of the filters are predesigned to guarantee weak correlation and highly efficient encoding. Leveraging a trained reconstruction network, the absolute spectra of various nonluminous samples are successfully reconstructed excluding the emitting spectrum of the light source and the spectral response of the detector. The remarkable reconstructed spectral imaging result for the color board is presented and the reconstructed spectra match well with the measured ones for different patches using the identical network. We utilized the least number of spectral encoders ever since to guarantee efficient encoding, along with the single thickness-variant modulation layer, which shows potential for mass, rapid, large-area production by combining deposition with nanoimprint. Instead of the synthetic Gaussian line shape spectra, a training dataset composed of diverse spectrum types is adopted to achieve fine generalization of the trained reconstruction network. In addition, by retraining the neural network, the reconstruction network is modified to fit for the actual filter functions of the spectral encoders, thus better reconstruction performance. The proposed miniaturized spectrometer has great prospects in the fields of consumer electronics, environmental monitoring, and disaster prevention.

Agricultural land use shapes dispersal in white-tailed deer (Odocoileus virginianus)

BackgroundDispersal is a fundamental process to animal population dynamics and gene flow. In white-tailed deer (WTD; Odocoileus virginianus), dispersal also presents an increasingly relevant risk for the spread of infectious diseases. Across their wide range, WTD dispersal is believed to be driven by a suite of landscape and host behavioral factors, but these can vary by region, season, and sex. Our objectives were to (1) identify dispersal events in Wisconsin WTD and determine drivers of dispersal rates and distances, and (2) determine how landscape features (e.g., rivers, roads) structure deer dispersal paths.MethodsWe developed an algorithmic approach to detect dispersal events from GPS collar data for 590 juvenile, yearling, and adult WTD. We used statistical models to identify host and landscape drivers of dispersal rates and distances, including the role of agricultural land use, the traversability of the landscape, and potential interactions between deer. We then performed a step selection analysis to determine how landscape features such as agricultural land use, elevation, rivers, and roads affected deer dispersal paths.ResultsDispersal predominantly occurred in juvenile males, of which 64.2% dispersed, with dispersal events uncommon in other sex and age classes. Juvenile male dispersal probability was positively associated with the proportion of the natal range that was classified as agricultural land use, but only during the spring. Dispersal distances were typically short (median 5.77 km, range: 1.3–68.3 km), especially in the fall. Further, dispersal distances were positively associated with agricultural land use in potential dispersal paths but negatively associated with the number of proximate deer in the natal range. Lastly, we found that, during dispersal, juvenile males typically avoided agricultural land use but selected for areas near rivers and streams.ConclusionLand use—particularly agricultural—was a key driver of dispersal rates, distances, and paths in Wisconsin WTD. In addition, our results support the importance of deer social environments in shaping dispersal behavior. Our findings reinforce knowledge of dispersal ecology in WTD and how landscape factors—including major rivers, roads, and land-use patterns—structure host gene flow and potential pathogen transmission.

Prediction Approach of Negative Rail Potentials and Stray Currents in Medium-Low-Speed Maglev

The problem of negative rail potentials (NRPs) appears in the line of the medium-low-speed (MLS) maglev. It is vital to forecast the NRP and the corresponding stray currents (SCs) in order to prevent safety hazards. This article proposes the prediction methods of NRP and SC for the first time for the MLS maglev. On the basis of developing a two-layer rail–earth circuit, a simplified prediction approach based on the analytical formula derivation is proposed to obtain the behaviors of NRP and SC under different steady running scenarios. Afterward, in order to accurately reveal the influence of vehicle-grid parameters, the ac component and the energy dispersal path of the maglev system are detailed, and the precise vehicle-grid model is developed to consummate the prediction approach using MATLAB. Under the premise of verifying the scheme effectiveness using the captured data in the on-site of the Chinese Xinzhu MLS maglev line, the scheme application studies are provided to investigate the behaviors of NRP and SC while considering the ac effect and the varying velocity of load current and rail–earth conductivity.

The Environmental Risk Assessment of Fire and Explosion in Storage Tanks of Petroleum Products

The present study provides a framework for assessing the environmental risk associated with fire and explosion of gasoline storage tanks in oil depots. The proposed framework includes three main steps: problem formulation, risk analysis, and risk description. The necessary basic details were identified and collected in formulating the problem. The source, pathway, receptor (SPR) model was employed in the risk analysis process. Each part was analyzed using tools that provide appropriate results and maintain the model integrity; additionally, the findings can be used in the whole process. The Dow Fire and Explosion Index (F&EI) was deployed to scrutinize the source, the pollutant dispersion and transmission path characteristics were measured to inspect the pathway, and the vulnerability indicators of the receptor and the degree of impact were determined to scrutinize the receptor. Finally, the risk assessment results were presented in the form of risk description tables. The purpose of this integration was to develop a framework thoroughly evaluating the risk associated with fire and explosion to the point of environmental consequences and providing a better understanding of the outcomes. This study, conducted for the first time specifically for an oil depot, provides an exhaustive view highly contributing to managers and decision makers.

Call for integrating future patterns of biodiversity into European conservation policy

AbstractGiven the unprecedented rates of global warming, widespread shifts in species’ distributions are anticipated to play a key role for their survival. Yet, current conservation policies often allocate priority to native species and their typical habitats, thereby preserving historic conditions rather than preparing for future species distributions. Policy initiatives aimed at halting biodiversity loss, such as the EU 2030 Biodiversity Strategy, could provide an opportunity to proactively integrate species’ future distributions into conservation objectives on an international scale, for example, by encouraging management actions that allow for species migration along projected paths of dispersal. Acknowledging climate‐tracking species as a conceptually distinct phenomenon, we qualitatively analyzed to which extent the EU 2030 Biodiversity Strategy and the legal framework it is embedded in, such as the Draft Note on Designation Criteria (ENV.D.3/JC) and the Framework for Blue and Green Infrastructure (SWD/2019/193), integrated climate‐trackers into their conservation objectives. We found that the Biodiversity Strategy did not explicitly incorporate future patterns of species distributions into conservation planning but emphasized the maintenance of historical community compositions and species distributions. While the commitments in these legal documents to nature restoration will certainly be helpful for biodiversity conservation today and after 2030, it may miss the chance to be a more comprehensive conservation policy.

Complete chloroplast genome of an invasive marine macroalga Ulva californica (Ulvophyceae, Chlorophyta)

Species belonging to Ulva (Ulvophyceae, Chlorophyta) are one of the major members of invasive seaweeds. Ulva californica Wille 1899 was originally believed to be native to the Pacific coast of North America, while in recent years it has been reported as exotic species, or new record, in Europe, the Mediterranean, Asia, and Oceania. However, the paths of global dispersal of U. californica are unclear. In addition, the species boundary between U. californica and a related species is somewhat disputed. Here, we reported that the complete chloroplast genome of U. californica is 92,126 bp in size, harboring 96 genes (GenBank accession no. MZ561475). The overall base composition was A (37.9%), T (37.4%), C (12.3%), and G (12.4%), similar to those from other Ulva species. The phylogenomic analysis showed that although U. californica was genetically closer to Ulva aragoënsis (Bliding) Maggs 2018 in [Krupnik N et al., 2018], they were clearly distinguishable, supporting the recent opinion that they should be separated into different species. The chloroplast genome data of U. californica would provide plenty resources for phylogeography analysis and monitor on bioinvasion.

On the Energy Dispersion of Magnetic Rossby Waves

The energy dispersion of magnetic Rossby waves has been investigated by applying the two-dimensional incompressible magnetohydrodynamic (MHD) equations in both uniform basic flow and basic magnetic field. The dispersion relation suggests that the magnetic Rossby waves can be divided into fast- and slow-propagating modes, respectively. The fast-propagating mode propagates eastward and is similar to the fast Alfvén waves. The energy dispersion speed is faster than the phase speed, which means the perturbation energy can lead the perturbations themselves to arrive downstream. The slow-propagating waves with smaller (larger) horizontal scales are similar to those of the slow Alfvén waves (Rossby waves). The zonal group velocity is slower than the zonal phase speed for the slow-propagating magnetic Rossby waves. For the slow-propagating waves that propagate eastward, this means that the perturbation energy may trigger new perturbations that are located upstream of the perturbations themselves. The group velocity vector is basically same as (opposite of) the wavevector for the fast-propagating (slow-propagating) magnetic Rossby waves that propagate eastward. The endpoints of the group velocity vectors and the wavevector multiplying a factor are located on a cycle in the wavenumber space. Due to the uniform basic flow and the uniform basic magnetic field, the energy dispersion paths (called rays) are straight lines. Along the straight-line rays, the wave action, wave energy, and amplitude keep their initial values, and the wave neither develops nor decays.

Comparing Genetic and Field-Based Estimates of Population Connectivity in Marbled Salamanders, Ambystoma opacum

Estimating connectivity is key for maintaining population viability for pond-breeding amphibians, especially in areas where habitat alterations occur. Here, we used genetic data (microsatellites) to estimate connectivity of marbled salamanders, Ambystoma opacum, among three focal ponds and compared it to field data (capture-mark-recapture estimates) of movement among the same ponds. In addition, we derived least-cost dispersal paths from genetic data and compared them to field connectivity estimates. We found that genetic and field estimates of dispersal were generally congruent, but field-based paths were more complex than genetic-based paths. While both methods complement each other in identifying important source-sink metapopulation dynamics to inform efficient conservation management plans, field data provide a more biologically accurate understanding of the spatial movement of individual marbled salamanders.

Numerical Investigation on the Droplet Dispersion inside a Bus and the Infection Risk Prediction

COVID-19 can be easily transmitted to passengers by inhaling exhaled droplets from the infected person in a bus. Therefore, studying droplet dispersion would provide further insight into the mechanism of virus transmission and predict the risk of infection among passengers on a bus. In this research, a bus equipped with air-conditioning was employed as the research object. To determine the dispersion path, concentration distribution, and escape time of the droplets, computational fluid dynamic (CFD) was applied to simulate the flow field and the droplets’ dispersion. The effect of the air supply rate, the location of vents, and the location of infected persons on the dispersion were discussed. Based on the distribution of droplets in the cabin calculated by CFD, a superposition method was used to determine the number of virus particles inhaled by every individual passenger over a four-hour journey. Then, infection risk was assessed by the Wells-Riley equation for all the passengers in the cabin after the whole journey. The results show that the distribution of droplets in the cabin is greatly influenced by the location of the infected person, and the airflow pattern is highly associated with the air supply rate and the location of vents. The infection risk of passengers located at the droplet dispersion path and the distance from the infected persons less than 2.2 m is over 10%. The increase in the air supply rate could speed up the spread of the droplets but at the same time, it could reduce the infection risk.

The late Pleistocene endemicity increase hypothesis and the origins of diversity in the Canary Islands Flora

AbstractAimWe explore the idea that most pre‐glacial non‐endemic Canarian flora became endemic to the archipelago by the extinction of its mainland populations during the late Pleistocene glaciations, implying that the extant non‐endemic flora is mostly post‐glacial: the ‘late Pleistocene endemicity increase hypothesis’.TaxonThe native flora of the Canarian archipelago.MethodsWe statistically compare the distributions of 2087 Canarian endemic and native non‐endemic plants across islands. We also carry out connectivity analyses using their dispersal paths, obtained by connecting all the islands of occurrence for each taxon.ResultsWhile the distribution of the endemic flora is strongly L‐shaped (with a much higher proportion of Single‐Island Endemics than Multiple‐Island Endemics), that of the native non‐endemics is U‐shaped (i.e. similar prevalence of single‐island taxa and taxa distributed on all islands). The native non‐endemics have a significantly lower proportion of single‐island taxa and a higher proportion of widespread taxa than the endemics. Most dispersal paths in the endemics connect the central and western islands, whereas they are extended across all islands in the native non‐endemics.Main conclusionsThe contrasting distributional patterns of the endemics and the native non‐endemics support an outstanding role of species diversification in the endemic flora, but a still negligible influence of the insular selective and stochastic pressures (including extinction) in the native non‐endemic flora, arguably due to its recent origin. Our results suggest that the high endemicity levels of the extant Canarian flora can be explained by two complementary processes: (i) high diversification rates throughout the ontogeny of the archipelago, often from colonisers that attained a widespread distribution prior to speciation, and (ii) an ‘endemicity increase’ during the late Pleistocene glaciations, whereby most of the pre‐glacial non‐endemic Canarian flora became endemic due to the extinction of its mainland conspecific populations, thus emphasising the role of the Canaries as climatic refugia.

Biogeographic reconstruction of the migratory Neotropical fish family Prochilodontidae (Teleostei: Characiformes)

AbstractGeographically, widespread Neotropical fish lineages offer opportunities to reconstruct historical biogeography patterns and infer processes leading to modern ichthyological diversity and distribution. The characiform family Prochilodontidae is well suited for such reconstruction because their migrations limit population substructure within river systems. Therefore, their biogeographic history should match closely the history of connectivity among Neotropical river basins. Here, we combine a time‐calibrated phylogeny with biogeographic model testing to recover the history of this family's diversification. Results support the Miocene rise of the Andean Eastern Cordillera as a dispersal barrier, but also indicate a much earlier Eocene origin of the trans‐Andean genus Ichthyoelephas. Despite the early origin of the family and its three constituent genera, most prochilodontid lineages originated during the Miocene in Greater Amazonia, likely due to drainage reorganizations caused by Andean uplift. Subsequent speciation appears linked to interbasin exchanges and expansions of Amazonian lineages into Brazilian coastal systems. The modern richness of Prochilodus in easterly drainages appears to be relatively young, with only Prochilodus vimboides likely reaching that region prior to the late Miocene. The rise of the Vaupes Arch coincides with two splits between Orinocoan and Amazonian lineages circa 9 million years ago (Ma). However, two instances of later dispersal between these drainages reveal the permeability of the Vaupes Arch, suggesting that it may promote periodic speciation. This study illustrates how model‐based biogeographic studies of widespread groups can reconstruct historic paths of dispersal and help reveal how landscape evolution promoted modern diversity patterns.

A Phylogeographical Analysis of the Beetle Pest Species Callosobruchus chinensis (Linnaeus, 1758) in China.

Simple SummaryCallosobruchus chinensis, a stored product pest, is difficult to control. In the study, the goal was to explore the causes of the demographic history, dispersal path and genetic variations underlying the spatial and temporal distribution of C. chinensis in China. The phylogeography of C. chinensis was analyzed by distribution modelling (SDM) under six periods and the least-cost path (LCP) based on combined mitochondrial DNA. Our data showed that the geographical isolation of the genetic lineages and the distribution range of C. chinensis were restricted by climate in different times. The landscape structure had influence on the genetic differentiation of C. chinensis. Although the migration ability of C. chinensis is limited, the development of transportation and trade is helping the insect spread, along with the beans of its host.Callosobruchus chinensis (Coleoptera Bruchidae), is a pest of different varieties of legumes. In this paper, a phylogeographical analysis of C. chinensis was conducted to provide knowledge for the prevention and control of C. chinensis. A total of 224 concatenated mitochondrial sequences were obtained from 273 individuals. Suitable habitat shifts were predicted by the distribution modelling (SDM). Phylogeny, genetic structure and population demographic history were analyzed using multiple software. Finally, the least-cost path (LCP) method was used to identify possible dispersal corridors and genetic connectivity. The SDM results suggested that the distribution of C. chinensis experienced expansion and contraction with changing climate. Spatial distribution of mtDNA haplotypes showed there was partial continuity among different geographical populations of C. chinensis, except for the Hohhot (Inner Mongolia) population. Bayesian skyline plots showed that the population had a recent expansion during 0.0125 Ma and 0.025 Ma. The expansion and divergent events were traced back to Quaternary glaciations. The LCP method confirmed that there were no clear dispersal routes. Our findings indicated that climatic cycles of the Pleistocene glaciations, unsuitable climate and geographic isolation played important roles in the genetic differentiation of C. chinensis. Human activities weaken the genetic differentiation between populations. With the change in climate, the suitable areas of C. chinensis will disperse greatly in the future.

Studying dispersed phase holdup in a pilot plant agitated liquid–liquid mixer by developing online expanded laser beam based technique

Expanded Laser Transmission Technique (E-LTT), where a laser beam is used in conjunction with a beam expander large enough to cover the average drop size up to a few millimeters in the path of the laser in a liquid–liquid dispersion mixture, has been applied for online continuous measurement and investigation in a non-invasive manner of the drop phase volume fraction in an agitated flow mixer of a pilot plant scale. The limitations of beam scattering by the drops through the dispersion path were overcome by having liquids of matching refractive indices enabled by the temperature control system. This study reports for the first time the continuous measurements of the line averaged dispersed phase holdup for a pilot plant scale liquid–liquid mixer equipped with a commercial design mixer, where the measurements have no limitations to the geometrical aspects. Experimental results from a cubic mixing tank with a dispersion depth of 30cm were discussed. Online measurements were carried out in the presence of a revolving impeller and transmission of the expanded laser beam. The net volume of the mixer was 20.42liter, and the dispersed phase holdup that was successfully measured ranged between 0.15 and 0.75. In this work, arrangement of the laser setup was made to scan and measure continuously the line average dispersed phase holdup along the height of the pilot plant scale of the flow agitated liquid–liquid mixer. The E-LTT measurements were validated by comparing their results with those obtained from the mixer by shut-down procedure.