Sequential Experiments Research Articles

Strong Replication Interference Between Hepatitis Delta Viruses in Human Liver Chimeric Mice

BackgroundHepatitis D Virus (HDV) is classified into eight genotypes with distinct clinical outcomes. Despite the maintenance of highly conserved functional motifs, it is unknown whether sequence divergence between genotypes, such as HDV-1 and HDV-3, or viral interference mechanisms may affect co-infection in the same host and cell, thus hindering the development of HDV inter-genotypic recombinants. We aimed to investigate virological differences of HDV-1 and HDV-3 and assessed their capacity to infect and replicate within the same liver and human hepatocyte in vivo.MethodsHuman liver chimeric mice were infected with hepatitis B virus (HBV) and with one of the two HDV genotypes or with HDV-1 and HDV-3 simultaneously. In a second set of experiments, HBV-infected mice were first infected with HDV-1 and after 9 weeks with HDV-3, or vice versa. Also two distinct HDV-1 strains were used to infect mice simultaneously and sequentially. Virological parameters were determined by strain-specific qRT-PCR, RNA in situ hybridization and immunofluorescence staining.ResultsHBV/HDV co-infection studies indicated faster spreading kinetics and higher intrahepatic levels of HDV-3 compared to HDV-1. In mice that simultaneously received both HDV strains, HDV-3 became the dominant genotype. Interestingly, antigenomic HDV-1 and HDV-3 RNA were detected within the same liver but hardly within the same cell. Surprisingly, sequential super-infection experiments revealed a clear dominance of the HDV strain that was inoculated first, indicating that HDV-infected cells may acquire resistance to super-infection.ConclusionInfection with two largely divergent HDV genotypes could be established in the same liver, but rarely within the same hepatocyte. Sequential super-infection with distinct HDV genotypes and even with two HDV-1 isolates was strongly impaired, suggesting that virus interference mechanisms hamper productive replication in the same cell and hence recombination events even in a system lacking adaptive immune responses.

Rational design of novel three-dimensional reticulated Ag2O/ZnO Z-scheme heterojunction on Ni foam for promising practical photocatalysis

Direct Z-scheme heterojunctions composed of Ag2O nanoparticles and ZnO nanorods were immobilized on Ni foam (AZN) via combined hydrothermal and precipitation methods to successfully construct 3D reticulated composites, and their photocatalytic performance were evaluated under simulated sunlight. Just as expected, the AZN samples exhibited excellent photocatalytic effects of 99.26% for the model pollutant (rhodamine B) in water after loading with Ag2O, which was 2.77 times higher than that of regular ZnO NAs/Ni foam composites. Meanwhile, the surface wettability of composite was remarkably enhanced. Besides, a series of photoelectrochemical measurements showed a significant improvement in the charge separation efficiency of AZN, which was attributed to the synergistic effect of direct Z-scheme heterojunction, matched energy band structure as well as 3D porous structure. Moreover, the AZN sample presented satisfactory stability after four cycles, meanwhile it displayed good removal performance against different types of antibiotics (Tetracycline, Sulfadiazine and Ciprofloxacin). The applicability and durability of AZN for rhodamine B degradation were evaluated by sequential batch experiments in a homemade simulated flowing water device. More importantly, the lower value of electrical energy per order indicated the photocatalyst/simulated sunlight system was more energy efficient and effective. Accordingly, this work provided a new strategy for designing 3D reticulated composites with low-dimensional nanomaterials to decompose organic pollutants in impaired waters.

Iron and magnesium isotope geochemistry in hydrothermal uranium ore systems: Insights from the Bong Deposit, Canada

The basement-hosted Bong uranium deposit in the Kiggavik region is associated with a broad hydrothermal alteration halo characterized by an inner illite-rich zone and an outer chlorite-rich zone. The uranium-bearing zones characterized by intense illite alteration yield high δ56Fe and δ26Mg values relative to the host rocks, with average whole-rock values of δ56Fe = 0.58 ± 0.15‰ and δ26Mg = 0.61 ± 0.29‰, and clay-size fraction values of δ56Fe = 0.51 ± 0.20‰ and δ26Mg = 0.82 ± 0.09‰. These isotopic values correlate with a decrease in average Fe2+ concentrations (0.47 versus 2.30 mol% Fe2+ in least-altered hosts).The high δ26Mg values reflect intense illite alteration, which preferentially incorporated heavier magnesium isotopes during alteration of both the ore zones and an upper hematite-altered horizon. Although the clay alteration with high δ56Fe and δ26Mg values coincides with the main uranium-bearing zone, the δ56Fe signatures reflect multiple stages of alteration and mineralization. The high δ56Fe values and lower Fe2+ contents of the uranium-bearing zones support leaching of Fe2+(aq) enriched in lighter iron isotopes. Sequential leach δ56Fe experiments also indicate that formation of fine-grained iron oxides/hydroxides with positive δ56Fe values (+0.23 to +0.60‰) in late chemical fronts enhanced the primary positive δ56Fe signatures recorded in ore zones. Near surface samples with similar isotopic signatures provide clues to buried mineralization and support structural disruption of the systems after primary mineralization. Distal geochemical expressions of this system may include enrichment in iron contents with negative δ56Fe values and/or negative δ26Mg whole-rock or clay-size fractions values, reflecting precipitation of the isotopically light iron and magnesium leached during hydrothermal alteration. Although more costly to process, sequential leach δ26Mg or δ56Fe analyses produced greater variance in the ore zones relative to background values and removed anomalous values from carbonate minerals. Isotopic analyses of the clay-size fraction produced results comparable to the final digestion in the sequential leach process but this method in particular requires greater understanding the mineralogical controls on the isotopic signatures.

Polymers from Sugars and Cyclic Anhydrides: Ring-Opening Copolymerization of a d-Xylose Anhydrosugar Oxetane

A d-xylose 3,5-anhydrosugar derivative has been used as an oxetane co-monomer in the ring-opening copolymerization (ROCOP) with cyclic anhydrides, to form a family of seven novel sugar-derived polyesters, with up to 100% renewable content. ROCOP proceeds with high alternating selectivity to form AB-type copolymers that are thermally robust (Td,onset > 212 °C) and exhibit a broad range of glass-transition temperatures (Tg 60–145 °C). These polyesters are amenable to further postpolymerization functionalization. The hydroxy group of the sugar moiety can be unveiled, then functionalized further, e.g., phosphorylated. The internal alkene of some of the anhydride moieties can also be subject to thiol-ene reactions. Combining those orthogonal strategies affords AB copolyesters with alternating functional substituents. By exploiting the living character of the ROCOP process, block copolymers have also been synthesized through sequential co-monomer addition experiments.

Dyeing Para-Aramid Textiles Pretreated with Soybean Oil and Nonthermal Plasma Using Cationic Dye.

The increasing use of functional aramids in a wide array of applications and the inert nature of aramids against conventional dye and print methods requires developing new dyeing methods. This study aims to use environmentally friendly method with a cationic dye as an alternative for dyeing para-aramid fabrics. Experiments used a multi-factorial design with functions of pretreatment, dye solvent (water and/or glycerol) and auxiliary chemical additives (swelling agent and surfactant) and a sequential experimentation methodology. The most effective dyeing procedures involved the following steps: (i) pretreatments of the fabrics with soybean oil and nonthermal plasma (NTP), (ii) using water at T = 100 °C as the dye solvent, and (iii) omitting other chemical additives. With a commercial cationic dye, these conditions achieved a color strength in K/S value of 2.28, compared to ~1 for untreated samples. FTIR analysis revealed that a functional network formed on the fibers and yarns of the fabrics by chemical reactions of excited plasma species with double bonds in the soybean oil molecules was responsible for significantly improving the color strength. These results extend the potential uses of a renewable material (soybean oil) and an environmentally friendly technology (NTP) to improve the dyeing of para-aramid textiles and reduce the use of harsh dye chemicals.

Evidence for extreme Sm[sbnd]Nd fractionation during chemical weathering

During subaerial chemical weathering, submarine weathering and other intracrustal processes, SmNd chemical fractionation remains uncertain, while a little is known about the conditions, scale and magnitude, specific processes and actual mechanism for possible SmNd fractionation. Here, an in situ terra rossa weathering profile developed on dolostone is chosen for the study. Based on sequential extraction experiments and measurements of the mineral and geochemical compositions including SrNd isotopic compositions, we suggest that subaerial chemical weathering not only leads to considerable SmNd mobilization, redistribution and secondary enrichment, but also gives rise to extreme SmNd fractionation, apparent 143Nd isotope homogenization, nearly complete resetting of the 147Sm143Nd isotope system, anomalous initial 143Nd/144Nd ratios, and meaningless 143Nd model age (TDM) for weathering products. We found that the lanthanide tetrad effect, rather than mineralogical control, is responsible for the observed substantial SmNd fractionation and for the other rare earth element fractionation. Under domination of the lanthanide tetrad effect, the mobility of Sm is preferential to that of Nd during their migration in the form of dissolved organic complexes. Our results also illustrate that resetting of the 147Sm143Nd isotope system in weathering products is controlled by the combined effect of the extraneous dissolved SmNd input and additional SmNd fractionation. Finally, we argue that similar scenarios may occur in submarine weathering, diagenesis and other geological processes.

An experiment on network density and sequential learning

We conduct a sequential social-learning experiment where subjects each guess a hidden state based on private signals and the guesses of a subset of their predecessors. A network determines the observable predecessors, and we compare subjects' accuracy on sparse and dense networks. Accuracy gains from social learning are twice as large on sparse networks compared to dense networks. Models of naive inference where agents ignore correlation between observations predict this comparative static in network density, while the finding is difficult to reconcile with rational-learning models.

Physiological effects of the interaction between Nosema ceranae and sequential and overlapping exposure to glyphosate and difenoconazole in the honey bee Apis mellifera

Pathogens and pollutants, such as pesticides, are potential stressors to all living organisms, including honey bees. Herbicides and fungicides are among the most prevalent pesticides in beehive matrices, and their interaction with Nosema ceranae is not well understood. In this study, the interactions between N. ceranae, the herbicide glyphosate and the fungicide difenoconazole were studied under combined sequential and overlapping exposure to the pesticides at a concentration of 0.1 µg/L in food. In the sequential exposure experiment, newly emerged bees were exposed to the herbicide from day 3 to day 13 after emerging and to the fungicide from day 13 to day 23. In the overlapping exposure experiment, bees were exposed to the herbicide from day 3 to day 13 and to the fungicide from day 7 to day 17. Infection by Nosema in early adult life stages (a few hours post emergence) greatly affected the survival of honey bees and elicited much higher mortality than was induced by pesticides either alone or in combination. Overlapping exposure to both pesticides induced higher mortality than was caused by sequential or individual exposure. Overlapping, but not sequential, exposure to pesticides synergistically increased the adverse effect of N. ceranae on honey bee longevity. The combination of Nosema and pesticides had a strong impact on physiological markers of the nervous system, detoxification, antioxidant defenses and social immunity of honey bees.

Eco-friendly immobilization of dithizone on coal bottom ash for the adsorption of lead(II) ion from water

Coal bottom ash is one of coal combustion wastes which mainly contains metal oxides of alumina and silica, thus it can be potentially used as adsorbent for heavy metal removal in aquatic environment. We have developed a new approach of eco-friendy immobilization of dithizone on activated coal bottom ash (CBA-Act) in water medium to yield dithizone-immobilized coal bottom ash (CBA-Dtz). The immobilization process in water medium is intended to replace previous method that uses more toxic organic solvents of toluene or carbon tetrachloride. Dithizone immobilization on CBA-Act is aimed to increase the selectivity and capacity of the adsorbent towards heavy metal ions. Characterization of the materials by FTIR (Fourier Transform Infra-Red), SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray), TEM (Transmission Electron Microscope), XRD (X-Ray Diffraction) and DSC/TGA (Differential Scanning Calorimetry/Thermogravimetric Analysis) confirms that dithizone immobilization on CBA-Act in water medium has successfully accomplished and the new approach has proved to be twice more effective than that done in toxic organic media. Application of the original and modified CBA-Act in the adsorption of lead(II) ion from water suggests that the adsorption capacity of CBA-Dtz increases approximately three times as much as that of CBA-Act. The adsorption on both adsorbents follows pseudo-2nd order kinetic and can be best described by either Langmuir or BET isotherm adsorption models. Sequential desorption experiments reveal that lead(II) adsorption on CBA-Act is mostly governed by electrostatic and hydrogen bond interactions. However, upon immobilization of dithizone as found in CBA-Dtz, electrostatic interaction decreases while hydrogen bond interaction increases significantly.

David W. Schindler—Icon and Iconoclast

David W. Schindler—Icon and Iconoclast

Effects of inhibitions by sodium ion and ammonia and different inocula on acetate-utilizing methanogenesis: Methanogenic activity and succession of methanogens

Acetate-fed anaerobic sequential batch experiments with four different inhibitory conditions (non-inhibitory (Lo), sodium-ion inhibitory (Na), ammonia inhibitory (Am), combined inhibitory (Hi)) were conducted using thirteen different inocula to investigate the inhibition effects by sodium-ion and ammonia and different inocula on acetate-utilizing methanogenesis and succession of methanogens. Sodium-ion and ammonia significantly extended lag-time λ and reduced specific-methanogenic-activity RCH4, and caused synergistic inhibition. The inhibition differed according to the initial methanogen community structures: the inhibition effects on λ and RCH4 were strongest ininocula with Methanosaeta concilii dominant and weakest in inocula with Methanoculleus bourgensis dominant. These inhibitory conditions determined the succession of methanogens: the most competitive methanogens were Methanosaeta concilii in Lo, Methanosarcina sp. in Na, Methanosarcina sp. and Methanoculleus bourgensis in Am, Methanoculleus bourgensis in Hi. This study provides valuable information for microbial management and optimization for AD processes treating wastewater that is rich in protein and/or salt.

Effects of insecticides on mortality, growth and bioaccumulation in black soldier fly (Hermetia illucens) larvae.

Residues of persistent insecticides may be present in the substrates on which insects are reared for food and feed, which may affect insect growth or survival. In addition, insecticidal substances may bio-accumulate in reared insects. The objective of this study was to assess potential effects of selected insecticides on the growth and survival of black soldier fly larvae (BSFL, Hermetia illucens) and on their safety when used as animal feed. Six insecticides (chlorpyrifos, propoxur, cypermethrin, imidacloprid, spinosad, tebufenozide) with different modes of action were tested in two sequential experiments. Cypermethrin was also tested with the synergist piperonyl butoxide (PBO). Standard BSFL substrate was spiked to the respective maximum residue level (MRL) of each insecticide allowed by the European Union to occur in feed; and BSFL were reared on these substrates. Depending on the observed effects in the first experiment, spiked concentrations tested in the second experiment were increased or reduced. At the concentrations applied (1 and 10 times MRL), three of the six tested substances (chlorpyrifos, propoxur, tebufenozide) did not affect the survival or biomass growth of BSFL, compared to the control (non-spiked) treatments. At MRL, imidacloprid stimulated the growth of BSFL compared to the controls. Spinosad and cypermethrin at the MRL level negatively affected growth and survival. The effects of cypermethrin appeared to be augmented by addition of PBO. A mean bio-accumulation factor of ≤0.01 was found in both experiments for all substances–except for cypermethrin, which was comparatively high, but still below 1 (0.79 at 0.1 mg/kg). The lack of accumulation of insecticides in the larvae suggests that there is no risk of larval products being uncompliant with feed MRLs. However, we conclude that insecticides present in substrates may affect growth and survival of BSFL. More research on a larger variety of substances and insect species is recommended.

Identification of the Key Role of NF-κB Signaling Pathway in the Treatment of Osteoarthritis With Bushen Zhuangjin Decoction, a Verification Based on Network Pharmacology Approach.

This study aimed to identify whether the NF-κB signaling pathway plays a key role in the treatment of osteoarthritis (OA) with Bushen Zhuangjin Decoction (BZD) based on a typical network pharmacology approach (NPA). Four sequential experiments were performed: 1) conventional high-performance liquid chromatography (HPLC), 2) preliminary observation of the therapeutic effects of BZD, 3) NPA using three OA-related gene expression profiles, and 4) verification of the key pathway identified by NPA. Only one HPLC-verified compound (paeoniflorin) was identified from the candidate compounds discovered by NPA. The genes verified in the preliminary observation were also identified by NPA. NPA identified a key role for the NF-κB signaling pathway in the treatment of OA with BZD, which was confirmed by conventional western blot analysis. This study identified and verified NF-κB signaling pathway as the most important inflammatory signaling pathway involved in the mechanisms of BZD for treating OA by comparing the NPA results with conventional methods. Our findings also indicate that NPA is a powerful tool for exploring the molecular targets of complex herbal formulations, such as BZD.

Biological activated carbon process for biotransformation of azo dye Carmoisine by Klebsiella spp.

ABSTRACT The feasibility of employing the biological activated carbon (BAC) process to debilitate azo dye Carmoisine by Klebsiella spp. was investigated. Plate assay revealed the capability of Klebsiella spp. for removal of Carmoisine via degradation. Kinetic parameters were measured for Carmoisine debilitation by Klebsiella spp. using the suspended anaerobic process. Two types of granular and rod-shaped activated carbon were used to form the biological beds in order to study the Carmoisine debilitation in batch processes. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to indicate the colonization and biofilm formation of bacteria grown on activated carbon particles (ACPs). Thin-layer chromatography (TLC), liquid chromatography–mass spectrometry (LC–MS), high-pressure liquid chromatography (HPLC) and biosorption studies demonstrated biotransformation of Carmoisine into its constituent aromatic amines during the Carmoisine debilitation in suspended anaerobic and BAC processes. The porosity of activated carbons, inoculation size and age of biological beds were the important factors affecting the viability of bacterial cells grown on ACPs and, consequently, the rate and efficiency of the Carmoisine debilitation process determined through spectrophotometry. The reusability of biological beds was demonstrated by conducting sequential batch experiments. In conclusion, the BAC process proved to be an efficient method for anaerobic dye degradation.

Study of extraction of iron (III) from chromium sulphate solution

ABSTRACT This work reports a study of the extraction of iron (III) deeply from the chromium sulphate solution in which most of the iron was precipitated with oxalic acid. Di(2-ethylhexyl)phosphoric acid (P204) was employed, and the conditions of the extraction process were optimised according to a sequential experiment design. The concentration of iron (III) in the solution could be reduced to less than 2 mg L−1 and the iron (III) extraction efficiency can reach up to 99.7% when the solution feed pH value, the phase ratio, P204 concentration, saponification rate, and extraction stages were 2.0, 1:1, 15% (v/v), 60%, and 2, respectively. During this process, other impurities in the solution such as Ni and Mn can also be reduced simultaneously. Further, post-extraction, highly pure chromium sulphate can be obtained. The experimental results show that when the organic was stripped with 4 mol L−1 HCl, 95% Fe in the organic phase can be stripped after three stripped series with O/A being 1:1, and then P204 can be re-utilised. The extraction process can also address the difficulty in separating iron (III) thoroughly from the chromium sulphate solution in the new chromic salt process with ferrochrome as raw material.

Enrichment of Trace Metals (V, Cu, Co, Ni, and Mo) in Arctic Sediments—From Siberian Arctic Shelves to the Basin

AbstractWith 50% of the Arctic Ocean is consisted of continental shelves, extensive shelf‐basin exchange processes exist here and plays a key role in regulating the biogeochemical recycling process of trace metals in the Arctic region. In this study, short sediment cores were collected along three transects from Siberian‐Chukchi shelves to adjacent slope/basin areas. An increasing trend was found for the bulk concentrations of several metals (V, Cu, Co, Ni, and Mo) from shelf to slope/basin cores with increasing water depth. Sequential extraction experiments indicated that the Fe/Mn oxide fractions increased significantly from shelf (9%–21%) to basin cores (24%–76%) for Cu, Co, Ni, and V, while the organic/sulfide phase remained significant (∼40%) for Mo. In addition, the observed dissolved metal concentrations in porewater indicated the remobilization of Fe, Mn, and Mo from shelf sediment, while V was always removed from water to the sediment, both on the shelf or in the slope/basin. Overall, in combination with the statistical analysis, we proposed that metals are transported from shelves to the central Arctic and are scavenged mainly by Mn oxides from the water column, which results in the enrichment of metals in slope/basin sediment. With the climate change, such transport and accumulation mechanism may be intensified over time, slowly leading the Arctic sediment to be a more and more important sink for those metals.

Deriving alpha angle from anterior-posterior dual-energy x-ray absorptiometry scans: an automated and validated approach

Introduction: Alpha angle (AA) is a widely used measure of hip shape that is commonly used to define cam morphology, a bulging of the lateral aspect of the femoral head. Cam morphology has shown strong associations with hip osteoarthritis (OA) making the AA a clinically relevant measure. In both clinical practice and research studies, AA tends to be measured manually which can be inconsistent and time-consuming. Objective: We aimed to (i) develop an automated method of deriving AA from anterior-posterior dual-energy x-ray absorptiometry (DXA) scans; and (ii) validate this method against manual measures of AA. Methods: 6,807 individuals with left hip DXAs were selected from UK Biobank. Outline points were manually placed around the femoral head on 1,930 images before training a Random Forest-based algorithm to place the points on a further 4,877 images. An automatic method for calculating AA was written in Python 3 utilising these outline points. An iterative approach was taken to developing and validating the method, testing the automated measures against independent batches of manually measured images in sequential experiments. Results: Over the course of six experimental stages the concordance correlation coefficient, when comparing the automatic AA to manual measures of AA, improved from 0.28 [95% confidence interval 0.13-0.43] for the initial version to 0.88 [0.84-0.92] for the final version. The inter-rater kappa statistic comparing automatic versus manual measures of cam morphology, defined as AA ³≥60°, improved from 0.43 [80% agreement] for the initial version to 0.86 [94% agreement] for the final version. Conclusions: We have developed and validated an automated measure of AA from DXA scans, showing high agreement with manually measuring AA. The proposed method is available to the wider research community from Zenodo.

Fluid-phase and membrane markers reveal spatio-temporal dynamics of membrane traffic and repair in the green alga Chara australis

We investigated the mechanisms and the spatio-temporal dynamics of fluid-phase and membrane internalization in the green alga Chara australis using fluorescent hydrazides markers alone, or in conjunction with styryl dyes. Using live-cell imaging, immunofluorescence and inhibitor studies we revealed that both fluid-phase and membrane dyes were actively taken up into the cytoplasm by clathrin-mediated endocytosis and stained various classes of endosomes including brefeldin A- and wortmannin-sensitive organelles (trans-Golgi network and multivesicular bodies). Uptake of fluorescent hydrazides was poorly sensitive to cytochalasin D, suggesting that actin plays a minor role in constitutive endocytosis in Chara internodal cells. Sequential pulse-labelling experiments revealed novel aspects of the temporal progression of endosomes in Chara internodal cells. The internalized fluid-phase marker distributed to early compartments within 10 min from dye exposure and after about 30 min, it was found almost exclusively in late endocytic compartments. Notably, fluid cargo consecutively internalized at time intervals of more than 1h, was not targeted to the same vesicular structures, but was sorted into distinct late compartments. We further found that fluorescent hydrazide dyes distributed not only to rapidly recycling endosomes but also to long-lived compartments that participated in plasma membrane repair after local laser injury. Our approach highlights the benefits of combining different fluid-phase markers in conjunction with membrane dyes in simultaneous and sequential application modus for investigating vesicle traffic, especially in organisms, which are still refractory to genetic transformation like characean algae.

High-fidelity hurricane surge forecasting using emulation and sequential experiments

Probabilistic hurricane storm surge forecasting using a high-fidelity model has been considered impractical due to the overwhelming computational expense to run thousands of simulations. This article demonstrates that modern statistical tools enable good forecasting performance using a small number of carefully chosen simulations. This article offers algorithms that quickly handle the massive output of a surge model while addressing the missing data at unsubmerged locations. Also included is a new optimal design criterion for selecting simulations that accounts for the log transform required to statistically model surge data. Hurricane Michael (2018) is used as a testbed for this investigation and provides evidence for the approach’s efficacy in comparison to the existing probabilistic surge forecast method.

Refining tree size and dose–response functions for control of invasivePinus contorta

AbstractExotic conifers are rapidly spreading in many regions of New Zealand, as well as in many other countries, with detrimental impacts on both natural ecosystems and some productive sector environments. Herbicides, in particular the active ingredient triclopyr, are an important tool to manage invasive conifers, yet there is a paucity of information that quantifies the amount of herbicide required to kill trees of different sizes when applied as a basal bark treatment. Two sequential experiments were conducted to define the amount of triclopyr required to kill individual invasive lodgepole pine (Pinus contortaDouglas ex Loudon), trees of different sizes when applied in a methylated seed oil to bark (either the whole stem or base of the tree) and to determine which tree size variates (height, diameter at breast height [DBH], crown diameter [CD]) or derived attributes (crown area, crown volume index) best characterized this dose–response relationship. The outcomes of the dose–response research were compared with field operations where triclopyr was applied to the bark of trees from an aerial platform. Applying the herbicide to the whole stem, as opposed to the base of the tree only, significantly increased treatment efficacy. The tree size variates DBH, CD, crown area, and crown volume index all provided good fits to the tree mortality data, with >91% prediction accuracy. Of these variates, CD provided the most practical measure of tree size for ease of in-field calculation of dose by an operator. Herbicide rates used in field operations were seven to eight times higher than lethal doses calculated from experimental data. Our results highlight the potential for substantial reductions in herbicide rates for exotic conifer control, especially if dose–response data are combined with remotely sensed quantitative measurements of canopy area or volume using new precision technologies such as unmanned aerial vehicles.