Laboratory Experiments Research Articles

Nitrogen Supply from Soil Organic Matter: Predictors and Implications for Recommended Nitrogen Application Rates in Northern Highbush Blueberry

Nitrogen (N) management is a key component to maintaining high productivity of northern highbush blueberry (Vaccinium corymbosum L.) and nitrogen is often supplied by applying ammonium-based fertilizers. It can also be supplied through mineralization of soil organic matter (SOM), although the amount released by SOM is difficult to predict and not always considered in the development and implementation of N fertility programs. Laboratory and field experiments were conducted to estimate the timing and magnitude of net N mineralization from SOM throughout the growing season, identify soil properties that can be measured commercially and used to predict net N mineralization across a range of SOM, and determine whether N requirements for maximizing yield and fruit quality of blueberry vary across soils with different amounts of SOM. The laboratory experiment was conducted for 6 months using soil samples collected from 10 representative commercial blueberry fields in northwest Washington. The soils contained 2% to 42% soil organic carbon (SOC). The mean net N mineralization rates were fastest during the first 3 to 4 months of incubation, corresponding to the period during which N uptake reaches its maximum in blueberry. Results indicated that the soil total N may be a useful predictor of the N supply from SOM (6.34 ± 1.13 kg⋅ha−1 increase in net N mineralization with each 0.1% increase in total N), but there was substantial variability in the N supply that could not by explained by the total N (P < 0.001; r2 = 0.433). The field experiment was conducted from 2019 to 2021 and included four mature, regionally representative, commercial fields of ‘Duke’ blueberry. The fields contained 3% to 28% SOC and were each fertilized with low, medium (control), or high N rates, corresponding to 33 to 50, 67 to 84, or 102 to 118 kg⋅ha−1 N per year, respectively. Although soil inorganic N levels suggested that N mineralization was substantial at sites with higher SOM, sites with lower SOM did not require more fertilizer N than those with higher SOM. Under the conditions of this experiment, even the lowest N rates were sufficient to sustain production for at least 3 years at each site. The findings of this study indicate that SOM may be an important contributor to N fertility in managed blueberry systems, and that yield and fruit quality can be maintained across various N fertilizer rates, including at rates <50 kg⋅ha−1 N. However, the long-term impacts of reducing N application rates remain unclear, and future research should monitor long-term changes in plant health and soil fertility associated with reduced N applications across diverse soils and production systems.

Geometric accuracy of rock joint surface impressions obtained by less-destructive thermoplastic resin-based method

A novel less-destructive field impression method that overcomes the uncertainties in stability assessments of rock joints in historical monuments, due to material sampling or existing destructive test limitations, has been developed. A thermoplastic resin with low fluidity and a short curing time is used to obtain the surface morphology of rock joints owing to its less destructive nature and wide applicability to the walls and ceilings of historical monuments. However, the insufficient filling of this thermoplastic resin can decrease the geometric accuracy of the impressions. Thus, the geometric accuracy of resin impressions and mortar replicas has been examined through laboratory experiments, and the results have been compared with those obtained using existing silicone-based methods, based on the statistical indicators associated with mechanical replicability. The indicator values of the method developed in this study were comparable to those of the replicas in previous studies that have sufficient geometric accuracy to satisfy mechanical replicability requirements. Furthermore, although roughness-coefficient-based methods underestimate the shear strength because of the insufficient filling of thermoplastic resins, they provide an acceptable safety margin in stability assessments of rock joints. The proposed method is suitable for conducting accurate stability assessments of historical monuments and ensuring their conservation.

Development of an in-service NDT system for storage tanks

The large storage tank is one of the major infrastructures. Once a leak occurs, it often causes environmental pollution and even catastrophic accidents. In the early years, the method of emptying tanks and cutting plates for defects inspection was adopted to avoid leakage. However, there exist some deficiencies such as large blindness, long downtime and high cost. Since there are many problems in the traditional testing, inspection without emptying the tank and without stopping production is an indispensable technical means to ensure the safe operation of the tank. An in-service non-destructive testing (NDT) system for storage tanks without emptying is developed in this paper, which mainly includes sensors, the signal processing module, the testing crawler, the winding and releasing mechanism and control module et. al. The sensors, signal processing module and testing crawler need to be placed into the tank from the roof man-hole by the crane, while the control module is located outside the tank. The sensor can realize the combined inspection of magnetic field leakage (MFL) and electromagnetic acoustic transducer (EMAT). The laboratory experiments indicate that the system can realize in-service inspection of the corrosion defects on the bottom and works well in water. The new testing system will overcome the shortage of off-line service inspection methods that emptying and cleaning tanks are needed before inspection and environmental risks are involved. These research works guarantee the safe operation of storage tanks and provide an alternative NDT system for storages related industrial projects.

Direct evidence of gas flushing oil in deep reservoirs: Insight from integrated fluid inclusion analyses

Gas flushing of oil has been proposed as an essential process for forming some condensate gas reservoirs based on laboratory experiments and modeling but such a process has rarely been documented in subsurface reservoirs. Here, we report a unique type of yellow-ringed oil inclusions (YROIs) discovered from a deep reservoir in the Kuqa Foreland Basin, Western China that recorded the gas flushing of oil process in the subsurface. The occurrence, composition, phase state and PVT conditions of YROIs during trapping were investigated using a suite of fluid inclusion analytical methods including fluid inclusion petrography, microthermometry, fluorescence spectroscopy, PVT modeling and molecular composition analysis.YROIs found in the reservoir are three-phase (solid–liquid-vapor) fluid inclusions at room temperature with solid rings of 2–3 μm thickness and estimated volume percentages varying between 5 % and 15 %. When heated the solid ring starts to melt at around 46 °C and homogenized with the liquid phase at or above their corresponding homogenization temperatures of coeval aqueous inclusions. YROIs have fluorescence spectral peaks between 530 nm and 550 nm and an elevated spectral shoulder around 650 nm when measured at room temperature; but most spectra show a distinct “blue shift” and an absence of the 650 nm shoulder when measured at their homogenization temperatures. Some YROIs with thick yellow rings show dual spectral peaks at 570 nm and 630 nm at room temperature and their spectral peaks do not change when remeasured at their homogenization temperatures. Molecular compositions derived from synchronous fluorescence spectra and GC-MS analysis suggest that the compositions of YROIs are rich in polyaromatic compounds. PVT modeling indicates that YROIs were trapped under high pressure conditions with a pressure exceeding 50 % of the corresponding hydrostatic pressure.YROIs are interpreted to have been trapped under an elevated temperature and overpressure condition (around 110 °C and 60 MPa) relating to an intensive (wet) gas flushing of an early-charged wax-rich oil. When light hydrocarbon components in the reservoir oil were partially removed by gas, the wax/resin components rich in polyaromatic hydrocarbon compounds may precipitate due to physio-chemical fractionation. YROIs were entrapped in subsurface from a heterogeneous hydrocarbon fluid containing variable amounts of wax/resin colloids, which subsequently coalesce to form solid rings adhering to the inner wall of oil inclusions at room temperature. The presence of yellow-ringed oil inclusions in a reservoir may be indicative of a rapid gas flushing of waxy oil under high pressure, and their minimum homogenization temperature may approximate their trapping temperature.

Linewidth measurement of external cavity lasers

Narrowband laser sources are used in applications that require high-precision or stable optical frequency. Such applications include high-resolution spectroscopy, long-distance measurement, and coherent optical communication. The linewidth of a laser is a direct measure of the laser's stability; therefore, characterization of laser linewidth is essential. In practice, however, determining a laser's linewidth is not a trivial task and typically requires expensive equipment or a complex experimental arrangement. This paper presents a straightforward, low-cost method based on unbalanced interferometry, which allows us to determine the visibility of fringe patterns as a function of the optical path difference and, consequently, the linewidth of the laser. As a test laser, we use a tunable external cavity laser source at around 780 nm, where an interference filter is employed for wavelength selection. Data obtained by applying the interferometric technique to this laser and the analysis of these data, along with the resulting linewidth value, are presented. Given that the described measurement setup is inexpensive, straightforward, and pedagogically accessible, it is well-suited for an instructional physics laboratory experiment and will also be of interest to laboratory researchers.

Impact-Echo for Crack Detection in Concrete with Artificial Intelligence based on Supervised Deep Learning

Aging concrete infrastructure such as bridges and tunnels need to be appropriately maintained in their service life because these structures must be employed with ensured safety level. Inspection and maintenance with reasonable measures are typically operated for the reinforced concrete before severe damage and failure are developed. Especially, the crack propagation in concrete can significantly affect the structural integrity, durability and overall performance of structural elements. Effective maintenance strategies are required for material and structural assessment with detection and repair of cracks to prevent further deterioration. Identification of cracks in concrete is effectively operated to extend the service life of structures for mitigating the potential safety hazards and minimize the repair costs. In order to detect the cracks in the concrete structure member, non-destructive testing (NDT) system can be often introduced to satisfy the technical issues in terms of damage evaluation and estimation of repair condition. Currently, various NDT methods have been utilized for quantitative analysis of internal damage/defects using elastic wave method such as impact-echo method, focusing on reflection of P-wave in concrete as wave propagation behavior. In experimental laboratory tests, concrete specimens are usually prepared with interior damages (cracks) which are simulated as embedded plastic plate or styrofoam. In this study, starch- type polysaccharide sheet is used to form the simulated cracks in concrete specimen. This study aims at applying impact-echo method with AI (Artificial Intelligence) to identify the internal crack information based on the waveform characteristics obtained from the elastic wave propagation behavior. The waveform results are converted to frequency spectrum by FFT analysis. Consequently, it is found in this study that AI, which is employed by supervised deep learning models, successfully evaluates the data and displays the probability of crack existence in concrete. Since FFT is a powerful algorithm that quickly converts a signal from the time domain to the frequency domain, it gives efficient analysis to the impact echo method for crack detection with the application of AI system.

Modifying Expansive Soil Characteristics with Xanthan Biopolymer Integration

Abstract: Expansive soils pose significant challenges in various engineering projects due to their tendency to swell and shrink with changes in moisture content. Traditional stabilization methods often come with environmental and economic drawbacks. This research paper explores the potential of xanthan biopolymer, a polysaccharide of microbial origin (Xanthomonas Campestris), as a sustainable and effective alternative for altering the engineering properties of expansive soils. Through laboratory experiments and analysis, the paper investigates the influence of xanthan biopolymer on key soil properties such as swelling behaviour, shear strength, and permeability. The findings provide insights into the feasibility and efficacy of using xanthan biopolymer for soil stabilization, offering a promising avenue for sustainable geotechnical engineering practices.

Assessing Environmental Impact: Organosolv Extraction of Cellulose Pulp from Wood Waste

In the upcoming years, the paper industry is expected rely on containerboard for packaging, with approximately 80% of it being made from recycled fibers by 2020. Creating a new supply chain for fibers could help mitigate possible shortages. In this context, wood waste emerges as a valuable resource with the potential to serve as a plentiful and cost-effective reservoir for generating new materials, as cellulose fibers. This study presents an assessment of the environmental impact associated with the organosolv extraction of cellulose pulp from wood waste based on a previous in lab study conducted by the authors. The increasing demand for sustainable materials has prompted exploration into alternative methods for cellulose pulp production, with a focus on minimizing environmental footprint. Organosolv extraction, a promising technique, involves the use of organic solvents and acid catalysts to break down lignocellulosic biomass, resulting in high-quality cellulose pulp production. To evaluate the environmental implications of this process, a comprehensive life cycle assessment (LCA) approach was adopted. The LCA framework considers all stages of the organosolv extraction process, from wood waste collection to cellulose pulp manufacture, using a gate-to-gate approach. The functional unit for assessment is set as one ton of cellulose pulp. The dataset utilized for the LCA comprises primary data obtained from laboratory experiments, complemented by secondary data sourced from literature and the Ecoinvent life cycle inventory database. Furthermore, sensitivity analysis was conducted to assess the influence of key parameters on the environmental performance of the organosolv extraction process, with a focus on variations in energy consumption to identify potential areas for optimization and improvement. In summary, this study emphasizes the environmental aspects of utilizing organosolv extraction for cellulose pulp production from wood waste. Further research is warranted to explore energy consumption during the organosolv process for obtaining more precise data and optimizing the process. This could be achieved through pilot-scale experiments or utilizing process simulation software.

Carbon Dioxide, Methane, and Synthetic Cattle Breath Volatiles Attract Host-Seeking Stable Flies, Stomoxys calcitrans.

Stable flies, Stomoxys calcitrans (L.), are blood-feeding ectoparasites of cattle. Host-seeking stable flies respond to various cattle host cues, but a potential role of cattle breath gases [carbon dioxide (CO2), methane (CH4)] and cattle breath volatiles (acetone, isoprene, 2-butanone, 2-propanol, propionic acid, 3-methyl butyric acid, phenol), alone or in combination, on host-seeking behavior of stable flies has not yet been comprehensively investigated. In laboratory and greenhouse experiments, we tested the hypotheses that (1) CO2 and CH4 interactively attract stable flies, (2) CO2 'gates' attraction of stable flies to CH4, and (3) breath volatiles on their own, or in combination with both CO2 and CH4, attract stable flies. In Y-tube olfactometer experiments, the blend of CH4 (0.5%) and CO2 (1%) in breathing air ('b-air') attracted significantly more female flies than CH4, or CO2, in b-air. The flies' responses to CH4 were contingent upon their prior or concurrent exposure to CO2. In two-choice experiments in a large greenhouse compartment, significantly more flies landed on the host-look-alike barrel that disseminated a blend of CO2 and CH4 in b-air (CO2/CH4/b-air) than on the barrel disseminating either b-air or CO2. Moreover, significantly more flies landed on the barrel that disseminated synthetic breath volatiles (SBVs) than on the barrel disseminating b-air. The blend of CO2/CH4/b-air and SBVs elicited more fly landings on barrels than CO2/CH4/b-air but not than SBVs. SBVs, possibly combined with both CH4 and CO2, could be developed as a lure to enhance trap captures of stable flies in livestock production facilities.

Application of Multi-Channel Synchronized Dynamic Strain Gauges in Monitoring the Neutral Axis Position and Prestress Loss of Box Girder Bridges

The aim of this paper was to explore the application of multi-channel synchronized dynamic strain gauges in monitoring the neutral axis (N.A.) position of prestressed concrete box girders. The N.A. position has recently been proposed as an indicator for monitoring the health of bridge structures. Laboratory experiments were conducted on a prestressed T−beam under different prestress level conditions to investigate the correlation between the prestress magnitude and the N.A. position. In the development of the multi-channel synchronized dynamic strain gauges, edge computing was employed to significantly reduce the amount of data transmitted from the sensor nodes on-site. In edge computing, only the dynamic strain response caused by the maximum vehicle load in each minute is transmitted. This approach greatly enhances the monitoring efficiency and enables the realization of on-site non-computer-based monitoring systems. The laboratory test results of the prestressed T−beam showed that the N.A. position tends to move slightly downward as the prestress force increases. In other words, when the prestress force decreases due to loss, the N.A. position exhibits a slight upward movement. This study selected a newly constructed prestressed box girder as the subject for on-site measurement of the N.A. position using multi-channel synchronized dynamic strain gauges shortly after the prestress was applied. The on-site monitoring data indeed revealed a gradual upward movement of the N.A. position. This phenomenon confirmed that soon after the completion of prestressed concrete bridges, there is a gradual loss of prestress due to the significant shrinkage and creep effects of the early-age concrete. The on-site monitoring result aligned with the findings from the laboratory experiments, where the N.A. position was observed to move upward as the prestress decreased.

The Impact of an Earthworm Digestion on the Chemical Compositions of Various Clay Minerals from Soils

Aims: The impact of living organisms activities in soils may generate various chemical and mineralogical changes. The objective of this study is to estimate the impact of earthworms on the chemistry of soil minerals such as the clay minerals. Study Design: An experiment was carried out integrating earthworms and clay minerals. The modifications due to this interaction between minerals and organic matter induced by earthworms’ digestion are discussed. Place and Duration of Study: Institut des Sciences de la Terre et de l’Environnement (UdS/CNRS), Université de Strasbourg, Strasbourg, France. Eight weeks of experiment for each type of clay. Methodology: The earthworm Lumbricus terrestris was used for digestion of illite and various smectite-type minerals, with or without peat moss, during a laboratory experiment at a constant temperature of 20°C during 8 weeks and under artificial 12 hour-light and 12 hour-dark cycles, for each digestion cycle. Results: The chemical elements extracted from smectites by the earthworm digestion appear to be mineral dependent. The behavior of K and radiogenic 40Ar is more dictated by the type of digested mineral than by the digestion process itself. The 87Sr/86Sr ratio of the acid leachates of the nontronite and peat mixture, before and after digestion, suggests that half of the digested matter corresponds to the digestive action of the earthworms, with the second half resulting from food. Digested clay material represents up to 30% and the peat moss the remainder of the mixtures. Conclusion: This study highlights the role of organic compounds generated by earthworms activities in transfer of elements to surface waters and soil fluids.

EXPRESS: Do Gender-Diverse Teams Deliver Better Operational Performance: an Experimental Study

The routines-based approach to operations management emphasizes the role of routines in operational performance. However, little is known about how gender diversity in teams could alter coordination and change behaviors of team members, potentially impacting performance. In this study, we report on two laboratory experiments that induce routines to assess the stability of coordination and adaptability to organizational changes across mixed-gender teams of varying diversity and empirically examine operational performance via routines. Based on frequentist and Bayesian statistical approaches, our findings reveal that compared to other mixed-gender teams, balanced-gender teams (a) attain stability in routines faster, (b) exhibit varying levels of adaptability to internal and external changes, and (c) deliver better economic benefits via resource- and time- efficiencies under normal and change conditions, and this is attributable to their higher pace of routine formation. We find the operational-performance effect more prominent in situations of change than in normal conditions. Alongside our theoretical contributions, our study has several implications for management and effective operations management in terms of team composition, hiring, and staffing decisions.

Optimizing the Shape of the Spinning Electrode for Needleless Coaxial Electrospinning

This work deals with designing the optimal shape of the spinning electrode to optimize the distribution of the electric field and suppress the formation of corona discharges on the surface of the electrode during electrospinning using direct current (DC). Some of the solutions used for electrospinning are solved in flammable solvents, such as PVB; therefore, corona discharges are hazardous, as they cause sparks that can cause fires and explosions. The shape optimization was carried out on a plate weir electrode, which uses the principle of free surface spinning. Using the electric field simulation, an analysis of the plate weir spinner was carried out, and its optimization was aimed at minimizing the occurrence of corona discharges, which negatively affect the spinning process. Based on the simulations’ results, the spinning electrode design parameters were adjusted so that an even distribution of the electric field over the entire active surface of the electrode was ensured, and the incidence of corona discharges was prevented. A laboratory experiment was used to validate the function of the design changes in the spinning electrode.

Biophoton emission-based approach of the effects of systemic insecticides on the survival of Eurydema ventralis Kolenati, 1846 (Hemiptera: Pentatomidae) and on the photosynthetic activity of oilseed rape

The choice of effective crop protection technologies is a key factors in the economical production of oilseed rape. Insecticides belonging to the group of active substances butenolides and diamides are active substances available as seed treatments in oilseed rape and promising control tools in the crop protection technologies. Our laboratory experiment demonstrated that the experimental insecticides flupyradifurone and cyantraniliprole are both effective against Eurydema ventralis (Hemiptera: Pentatomidae) when used as a seed and in-crop treatments, but there is a fundamental difference in their insect mortality inducing effects. Flupyradifurone was found to have a total mortality 96 h after application based on basipetal translocation. In the case of cyantraniliprole, the insecticidal effect of the same treatment was 27% less. The experiment showed that the acropetal translocation of the tested active substances after seed treatment did not induce efficacy comparable to that of the basipetal translocation. The study of the biophoton emission of the plants demonstrated a verifiable correlation between the different application methods of the insecticides and the photon emission intensity per unit plant surface area. In conclusion, the systematic insecticides tested, in addition to having the expected insecticidal effect, interfere with plant life processes by enhancing photosynthetic activity.

Entomological assessment of hessian fabric transfluthrin vapour emanators as a means to protect against outdoor-biting Aedes after providing them to households for routine use in Port-au-Prince, Haiti.

A simple treated fabric device for passively emanating the volatile pyrethroid transfluthrin was recently developed in Tanzania that protected against nocturnal Anopheles and Culex mosquitoes for several months. Here these transfluthrin emanators were assessed in Port-au-Prince, Haiti against outdoor-biting Aedes. Transfluthrin emanators were distributed to participating households in poor-to-middle class urban neighbourhoods and evaluated once every two months in terms of their effects on human landing rates of wild Aedes populations. A series of three such entomological assessment experiments were conducted, to examine the influence of changing weather conditions, various transfluthrin formulations and emanator placement on protective efficacy measurements. Laboratory experiments assessed resistance of local Aedes aegypti to transfluthrin and deltamethrin, and the irritancy and repellency of the transfluthrin-treated fabric used in the field. Across all three entomological field assessments, little evidence of protection against wild Ae. aegypti was observed, regardless of weather conditions, transfluthrin formulation or emanator placement: A generalized linear mixed model fitted to the pooled data from all three assessment rounds (921 females caught over 5129 hours) estimated a relative landing rate [95% Confidence interval] of 0.87 [0.73, 1.04] for users of treated versus untreated emanators (P = 0.1241). Wild Ae. aegypti in this setting were clearly resistant to transfluthrin when compared to a fully susceptible colony. Transfluthrin emanators had little if any apparent effect upon Aedes landing rates by wild Ae. aegypti in urban Haiti, and similar results have been obtained by comparable studies in Tanzania, Brazil and Peru. In stark contrast, however, parallel sociological assessments of perspectives among these same end-users in urban Haitian communities indicate strong satisfaction in terms of perceived protection against mosquitoes. It remains unclear why the results obtained from these complementary entomological and sociological assessments in Haiti differ so much, as do those from a similar set of studies in Brazil. It is encouraging, however, that similar contrasts between the entomological and epidemiological results of a recent large-scale assessment of another transfluthrin emanator product in Peru, which indicate they provide useful protection against Aedes-borne arboviral infections, despite apparently providing only modest protection against Aedes mosquito bites.

Experiential Marketing to Gen Z: Fine-Tuning Brand Experience Through Virtual Reality

Market research highlights Generation Z’s increasing demands for digital brand experiences that inspire word-of-mouth sharing. Virtual reality (VR), an immersive affordances technology, holds promise for experiential marketing due to its power to transform experiences. Yet, limited research has examined how VR influences different facets of brand experiences that empower brand engagement and word-of-mouth. In Study 1, a laboratory experiment demonstrates that VR prompts higher sensory, intellectual, and behavioral brand experiences and word-of-mouth compared to static images and 360° tours, with equal brand engagement as a 360° tour. Study 2 corroborates these findings through a thematic analysis of qualitative insights from Generation Z consumers. This research underscores VR’s vital role in fine-tuning brand experience and brand engagement in the experiential marketing context.

The role of a smile in customer–employee interactions: Primitive emotional contagion and its boundary conditions

AbstractBy investigating emotional contagion in customer–employee interactions using the emotional facial action coding system, this study offers a means to separate primitive emotional contagion from its conscious counterpart. As an empirical validation of primitive emotional contagion and its impact on customer satisfaction, the multifaceted research approach, involving an experimental laboratory study and two field studies in hospitality and retail settings, reveals consistent findings. Additionally, the influence of emotional contagion on customer satisfaction is moderated by the esthetic appeal of the interior design. This work advances the theoretical understanding of the dynamics of primitive emotional contagion; it also offers practical insights regarding the importance of interior designs and busyness for enhancing service interactions.

Trichoderma spp. isolates stimulate rice seedling growth of Sertani 13 variety

Trichoderma has become one of the most studied filamentous fungi to be used as a greener and more sustainable solution for improving the production and growth of numerous crops, due to its capability to form symbiotic associations with plants. This study aimed to evaluate the effect of Trichoderma isolates obtained from the rhizosphere of organic rice fields in Sukabumi, Indonesia, in enhancing rice germination and seedling growth. A laboratory experiment used a completely randomized design consisting of seed treatments of 21 Trichoderma isolates (T1-T21) and a control treatment without Trichoderma (C). The inoculation was employed to elucidate any potential effects of Trichoderma isolates. Results showed that five isolates, i.e., T5, T7, T9, T10, and T14 stimulated the highest seedling vigor index, root and shoot length, and fresh weight and dry weight. These findings exhibited the potential of these five isolates as plant growth-promoting fungi to improve rice seedling growth and contribute to our understanding of the role of symbiotic fungi in sustainable rice crop production. Keywords: plant growth promoting fungi; seed treatment; plant-microbe interactions, symbiotic fungi

Impact failure and disaster processes associated with rockfalls based on three‐dimensional discontinuous deformation analysis

AbstractRockfalls, a common geohazard in mountainous areas, have destructive impact capacity and may cause failure of dangerous rock masses in their runout range. For slope risk assessment, a thorough understanding of the impact failure processes and dynamic characteristics associated with rockfall movements is necessary. The aim of this study is to investigate the impact of rockfall failure behaviours and disaster processes on the dangerous rock mass along the way through three‐dimensional discontinuous deformation analysis (3D DDA). To validate the reliability and applicability of 3D DDA, numerous laboratory experiments are performed on the impact of downward moving blocks on the unstable block and block system (i.e. single block–single block, single block–block system and block column–block system models) by comparing the displacements, kinetic energies and movement states of blocks. Using the G318 national road in Tibet as an example, 3D DDA simulates the impact and disaster processes associated with upper rockfalls sourced from a complete giant block and multiple discrete blocks on lower dangerous rock mass. Further, rockfall failure modes, movement characteristics, block interactions and impact phenomena are investigated. Results show that 3D DDA can effectively simulate block movement and impact interaction. The upper rockfalls impact the initially stable lower dangerous rock mass, which is the triggering factor for failure of the lower dangerous rock mass. The blocks from the upper rockfalls interact and merge to move downward, increasing the total volume and impact capacity of the rockfalls. It has been discovered that the rockfall disaster caused by the impact of an upper rockfall comprising discrete blocks on a lower dangerous rock mass is more severe than that resulting from the impact of a complete block. Overall, the results of this research can be used to help predict and prevent rockfall disasters.

Catch and release: controlling eastern yellowjacket Vespula maculifrons colonies using horizontal insecticide transfer.

Horizontal insecticide transfer is thought to play an important role in controlling a wide range of urban pests including ants, bed bugs, cockroaches and termites. Trap-treat-release is an effective experimental approach that has been used to successfully manage populations of invasive ants in field applications. Trap-treat-release is based on the principles of horizontal transfer. Individuals are captured, treated with the toxicant and released back into the environment. The treated individuals then return to the colony and transfer the toxicant to other members of the population resulting in secondary mortality. The goal of the current study was to evaluate the efficacy of the trap-treat-release technique for controlling field populations of the eastern yellowjacket, Vespula maculifrons. Laboratory experiments demonstrated that fipronil was highly toxic against V. maculifrons across a wide range of concentrations. Furthermore, fipronil was efficiently transferred from treated donors to untreated recipients and caused significant secondary mortality. A field experiment utilized trap-treat-release and demonstrated that fipronil was effectively transferred when foraging worker wasps are trapped, treated, released and allowed to return to their respective colonies. The trap-treat-release method may be an effective alternative to direct nest treatments and could help alleviate problems such as insecticide runoff, environmental contamination, and non-target effects. This method has the potential to provide effective management of social wasps. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.