Intrinsic Rate Research Articles

Impacts of Fulvic Acid on the Toxicity of the Herbicide Atrazine to Lemna minor.

Fulvic acids (FA) are environmentally prevalent components of dissolved organic carbon. Little research has evaluated their potential influence on the bioavailability of herbicides to non-target aquatic plants. This study evaluated the potential impacts of FA on the bioavailability of atrazine (ATZ) to the aquatic plant Lemna minor. Plants were exposed to 0, 15, 30, 60, 125, and 750µg/L ATZ in media containing three FA concentrations (0, 5, and 15mg/L) in a factorial study under static conditions. Fronds were counted after 7- and 14-days exposure and intrinsic growth rates (IGR) and total frond yields were calculated for analysis. Atrazine NOAECs and LOAECs within each FA treatment series (0, 5, or 15mg/L) were identified and EC50s were estimated. NOAEC/LOAECs for yield and IGR were 60/125 µg/L except for yield in the 0mg/L-FA series (30/60) and IGR in the 5mg/L-FA series (30/60). NOAEC/LOAECs were 30/60 µg/L for all treatments and both endpoints after 14 days exposure. EC50s ranged from 88.2 to 106.1µg/L (frond production 7 DAT), 158.0-186.0µg/L (IGR, 7 DAT), 74.7-86.3µg/L (frond production, 14 DAT), and 144.1-151.3µg/L (IGR, 14 DAT). FA concentrations did not influence the toxicity of ATZ.

Life table parameters of Amblyseius largoensis, Amblyseius swirskii and Proprioseiopsis lenis (Acari: Phytoseiidae) fed on eggs and larvae of Frankliniella occidentalis.

The immature development and reproduction of the predatory mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were investigated using both thrips eggs and first instars of the western flower thrips, Frankliniella occidentalis Pergande, as prey in a controlled laboratory environment at 25°C and 60% relative humidity. When provided with thrips eggs as food, A. largoensis exhibited a notably shorter immature development period for both males (7.05 days) and females (6.51 days) as compared with A. swirskii (8.05 and 7.19 days, respectively) and P. lenis (8.10 days and 7.05 days, respectively). Amblyseius largoensis also displayed a higher oviposition rate (2.19 eggs/female/day) than A. swirskii and P. lenis (1.79 and 1.78 eggs/female/day, respectively). Moreover, it exhibited the highest fecundity (25.34 eggs/female), followed by P. lenis (24.23 eggs/female) and A. swirskii (22.86 eggs/female). These variations led to A. largoensis having the highest intrinsic rate of increase (rm) at 0.209, followed by A. swirskii at 0.188, and P. lenis at 0.165. However, when the predatory mites were provided with first instars of F. occidentalis, A. swirskii demonstrated a faster immature development period for both males (7.67 days) and females (7.59 days) as compared with P. lenis (9.00 days and 7.86 days, respectively) and A. largoensis (8.47 days and 8.61 days, respectively). While the oviposition rates of P. lenis (1.92 eggs/female/day) and A. swirskii (1.90 eggs/female/day) were similar when feeding on this prey, A. largoensis produced fewer eggs (1.83 eggs/female/day). Further, A. swirskii exhibited the highest fecundity (31.93 eggs/female), followed by A. largoensis (25.71 eggs/female) and P. lenis (23 eggs/female). Consequently, the intrinsic rate of increase (rm) on thrips first instars was highest in A. swirskii (0.190), followed by A. largoensis (0.186), and P. lenis (0.176). In summary, our findings indicate that in terms of life history parameters A. largoensis performs optimally when feeding on thrips eggs, whereas A. swirskii performs best when preying on the mobile first instars of the thrips. These insights into the dietary preferences and reproductive capabilities of the studied predatory mite species have important implications for their potential use as biological control agents against F. occidentalis in agricultural settings.

Effects of Prey Switching at Different Stages on Life Parameters of Neoseiulus bicaudus

The phenomenon of prey switching is prevalent in the natural world and represents a strategic adaptation of predators to their environment. Neoseiulus bicaudus, a native predatory mite found in Xinjiang, serves as a natural enemy to numerous small pests. The utilization of Tyrophagus putrescentiae as an alternative prey for the mass breeding of N. bicaudus is employed to fulfill the demands of enhanced breeding efficiency and cost-effectiveness. Following the introduction of mass breed N. bicaudus into the agricultural ecosystem, there was a switching in the prey of N. bicaudus from Ty. putrescentiae to Tetranychus turkestani. The objective of this study was to investigate the impact of prey switching at various stages on N. bicaudus. This study employed the age-stage, two-sex life table to assess the life parameters of N. bicaudus undergoing prey switching at different stages. The results showed that the survival rate of N. bicaudus was significantly decreased, the developmental period was significantly prolonged, the fecundity was improved during prey switching, and the intrinsic rate of increase of N. bicaudus was significantly decreased. The negative effects of prey switching in larva and deutonymph stages were greater than those in protonymph and adult stages. The stage and age of N. bicaudus undergoing prey switching were positively correlated with the male ratio, and negatively correlated with the total preoviposition period and the mean generation time. The comprehension of prey switching effects on N. bicaudus can enhance our understanding of the predator adaptation to environmental changes and contribute to the artificial rearing and application of natural enemy.

Combining temperature-dependent life table data into Insect Life Cycle Model to forecast fall armyworm Spodoptera frugiperda (JE Smith) distribution in maize agro-ecological zones in Africa.

The fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), an invasive agricultural pest, has significantly impacted crop yields across Africa. This study investigated the relationship between temperature and FAW life history traits, employing life cycle modeling at temperatures of 20, 25, 28, 30, and 32°C. The development time for eggs, larvae, and pupae varied from 0-3 days, 10-18 days, and 7-16 days, respectively. The optimal temperature range for immature stage survival and female fecundity was identified as 21-25°C, with the intrinsic rate of increase (rm) and gross reproductive rate (GRR) peaking at 25-28°C. Model validation confirmed the accuracy of these findings. The research further projected the Establishment Risk Index (ERI), Activity Index (AI), and Generation Index (GI) for FAW under current and future climates (2050 and 2070) using RCP 2.6 and RCP 8.5 scenarios. Results indicate that RCP 2.6 leads to a reduction in high-risk FAW areas, particularly in central Africa. Conversely, RCP 8.5 suggests an increase in areas conducive to FAW activity. These findings highlight the impact of climate policy on pest dynamics and the importance of incorporating climatic factors into pest management strategies. The study predicts a potential decrease in FAW prevalence in West Africa by 2070 under aggressive climate mitigation, providing a basis for future FAW management approaches.

Methods for comparing theoretical models parameterized with field data using biological criteria and Sobol analysis

Prey–predator models are frequently developed to investigate trophic webs and to predict the population dynamics of prey and predators. However, the parameters of these models are often implemented without empirical data and may even be chosen arbitrarily. Commonly, only a few parameters are tested regarding their sensitivity and it is rare to read about the comparison between different prey–predator models (i.e. predation function structure). Here, we propose a method to compare four prey–predator models designed for two populations. We then apply this method to select the more biologically plausible one to model a simplified agricultural trophic system, including one predator compartment (the red fox Vulpes vulpes) and one prey group compartment (small mammals). These models are based on four Holling functional responses for the predation interaction and take the prey intrinsic growth rate into account through a Verhulst logistic function. Most parameters’ values (like attack rates or growth rates) were calculated from field data or based on literature review. We then used Sobol indices to conduct parameter exploration around mean parameter values to investigate and compare the model dynamics responses. Our first results showed that under our assumptions, the two most relevant models for our case study are the saturated Holling I and II models. We were also able to discriminate that among the 6 scaled parameters that vary, the model outputs are particularly sensitive to four of them (κ: saturation rate of the environment, Tr1: characteristic intrinsic decay time of the predators, Tc: characteristic growth time of the predator via the predation on the prey and λ: saturation rate of a predator’s stomach per time unit) and much less sensitive to two others (Tr2: characteristic intrinsic growth time of the prey and Ta: characteristic decay time of the prey due to the predation). These first encouraging results open the way for the next step, which will be to adapt this model construction to more complex prey–predator systems, with several predator and/or several prey compartments.

Testing the Effects of Prey Type on the Life History and Population-Level Parameters of Chrysoperla externa (Neuroptera: Chrysopidae)

Green lacewings are valuable predators, utilized in augmentative biological control against various agricultural pests. However, further studies are required to comprehend the performance of these predators when consuming natural prey. We investigated the capacity of Chrysoperla externa (Hagen) to utilize the following three distinct prey types: the pupae of the coffee leaf miner Leucoptera coffeella (Guérin-Mèneville & Perrottet), the eggs of the sugarcane borer Diatraea saccharalis (F.), and the eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller). The first two of these species are naturally occurring prey found in field crops, while the last serves as a factitious prey species for the mass rearing of natural enemies. We hypothesized that the type of prey would differentially affect the life history and population-level parameters of C. externa. Laboratory experiments were conducted to compare the pre-imaginal survival and developmental times, adult longevity and reproduction, and population growth of C. externa when larvae were provided with each of the three prey items. Results indicated that C. externa utilized the two natural prey items, L. coffeella pupae and D. saccharalis eggs, for its development, reproduction, and population growth. However, larvae developed significantly faster and females exhibited higher reproductive parameters, including fecundity and daily oviposition, when consuming the factitious prey, E. kuehniella eggs. This resulted in a higher intrinsic rate of population increase, as well as shorter times for the population to double in size. Understanding the population dynamics of C. externa when consuming different prey items is crucial for optimizing their utilization in augmentative biological control programs.

Performance and preference of larval parasitoid, Microplitis pallidipes (Hymenoptera: Braconidae), on 2 Spodoptera pest species.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

Evolution of dispersal and the analysis of a resource flourished population model with harvesting

This study explores a spatially distributed harvesting model that signifies the outcome of the competition of two species in a heterogeneous environment. The model is controlled by reaction-diffusion equations with resource-based diffusion strategies. Two different situations are maintained by the harvesting effects: when the harvesting rates are independent in space and do not exceed the intrinsic growth rate; and when they are proportional to the time-independent intrinsic growth rate. In particular, the competition between both species differs only by their corresponding migration strategy and harvesting intensity. We have computed the main results for the global existence of solutions that represent either coexistence or competitive exclusion of two competing species depending on the harvesting levels and different imposed diffusion strategies. We also established some estimates on harvesting efforts for which coexistence is apparent. Also, some numerical results are exhibited in one and two spatial dimensions, which shed some light on the ecological implementation of the model.

Can competitive effects and responses of alien and native species predict invasion outcomes?

The relative competitive ability of native and alien species, which consists of competitive effect (CE) and response (CR), has often been invoked as a key determinant of invasion success. Previous studies have reported that an alien species with a high CE and /or a low CR would successfully invade a native species. However, no studies have yet empirically examined the hypothesis or tested the consistency of invasion outcomes predicted by the CE-CR framework and modern species coexistence theory (MCT). To fill this research gap, we conducted a pairwise competition experiment between five alien and five native species, quantified CE and CR based on their biomass in the absence and presence of one competitor, and predicted invasion outcomes based on both CE-CR and MCT frameworks. We have demonstrated theoretically that the CE and CR frequently measured in previous work are only approximations of interspecific competitive coefficients, and thus could not completely predict the invasion outcomes. As we expected, the invasion outcomes predicted by the CE-CR framework were partially consistent with the predictions by the MCT framework. Specifically, aliens with low CR and high CE tended to exclude natives, while aliens with high CR and low CE tended to be excluded by natives according to MCT. In contrast, pairs of stable coexistence and priority effects did not conform to the theoretical expectation. Despite the theoretical defects of the CE-CR framework, it can provide some useful value in predicting the invasion outcomes, especially when intrinsic growth rate and intraspecific competition coefficients are not available. Our study is the first to compare invasion outcomes separately derived from qualitative (the CE-CR framework) and quantitative (the MCT framework) methods. We recommend that future research should adopt quantitative approaches such as MCT as far as possible, to more comprehensively understand and predict the biotic outcomes of interacting species.

Increasing the accuracy of exchange parameters reporting on slow dynamics by performing CEST experiments with ‘high’ B1 fields

Over the last decade chemical exchange saturation transfer (CEST) NMR methods have emerged as powerful tools to characterize biomolecular conformational dynamics occurring between a visible major state and ‘invisible’ minor states. The ability of the CEST experiment to detect these minor states, and provide precise exchange parameters, hinges on using appropriate B1 field strengths during the saturation period. Typically, a pair of B1 fields with ω1 (=2πB1) values around the exchange rate kex are chosen. Here we show that the transverse relaxation rate of the minor state resonance (R2,B) also plays a crucial role in determining the B1 fields that lead to the most informative datasets. Using K=kexkex+R2,B12 ≥ kex, to guide the choice of B1, instead of kex, leads to data wherefrom substantially more accurate exchange parameters can be derived. The need for higher B1 fields, guided by K, is demonstrated by studying the conformational exchange in two mutants of the 71 residue FF domain with kex ∼ 11 s−1 and ∼ 72 s−1, respectively. In both cases analysis of CEST datasets recorded using B1 field values guided by kex lead to imprecise exchange parameters, whereas using B1 values guided by K resulted in precise site-specific exchange parameters. The conclusions presented here will be valuable while using CEST to study slow processes at sites with large intrinsic relaxation rates, including carbonyl sites in small to medium sized proteins, amide 15N sites in large proteins and when the minor state dips are broadened due to exchange among the minor states.

Biology and life table parameters of Paralobesia viteana (Lepidoptera: Tortricidae), grown on different grape cultivars.

The grape berry moth, Paralobesia viteana (Clemens), is an important pest of cultivated grapes in eastern North America. Damage is caused directly by larval feeding of grape clusters and indirectly by increasing fruit susceptibility to fungal and bacterial pathogens. Despite the impact of grape berry moth on grapes being widely recognized, there is a lack of understanding of the influence that different grape cultivars may have on grape berry moth development, reproduction, and population dynamics. In this study, we constructed age-stage 2-sex life tables for grape berry moth fed on 5 grape cultivars: Concord, Niagara, Riesling, Chambourcin, and Vidal, to examine the effects of diet on insect population development, survival, reproduction, and demographic parameters such as net reproductive rate, intrinsic rate of increase, finite rate of increase, and mean generation time. Our findings reveal that grape cultivar significantly influenced the neonate wandering period, larval developmental time, adult and female longevity, pupal weight, adult preoviposition period, oviposition period, mean generation time, age-stage-specific life expectancy, and reproductive value of P. viteana. However, diet type did not affect grape berry moth total fecundity or other demographic parameters. The highest female reproductive value was observed at 30-40 days of age, indicating that control tactics implemented during this time frame would have the greatest impact on reducing population increase. This study provides critical information on the effects of different grape cultivars on grape berry moth development, reproduction, and demography. These insights could lead to the development of management strategies that improve pest control and reduce economic losses in vineyards.

Biochemical features of tomato under the influence of gibberellin and its impact on life table and physiology of Tuta absoluta (Merick) (Gelechiidae, Lepidoptera) reared on tomato

The Tomato leaf miner Tuta absoluta is an important agricultural pest and exerts a considerable influence on tomato production across the world. In the present research tomato plants were sprayed with a gibberellin solution at a concentration of 50 µM. The gibberellin treatment resulted in a prolonged duration of T. absoluta preadult stage (33.67 days) compared to control group (27.38 days). The fecundity rate in treated females (82.33 eggs/female) was lowered compared to the controls (96.92 eggs/female). The intrinsic rate of increase (r) (0.080 day−1) was also reduced in treatments compared with the control (0.110 day−1). The finite rate of increase (λ) in treatment (1.084 day−1) decreased compared to the controls (1.116 day−1). The antioxidant system enzymes of T. absoluta, including catalase, peroxidase, and superoxide dismutase (SOD) were increased in treated insects. The gibberellin also increased the activity of detoxifying enzymes including Glutathione s-transferase with two substrates (DCNB and CDNB) and cytochrome P450 compared to the control group. While general esterase did not show significant differences in treatment and control. The secondary metabolites in treated plants including total sugar, total phenol content, anthocyanin, flavonoid and tannin showed an increasing trend. The results clearly show the negative impact of gibberellin on life table and physiology of the tomato leaf miner and can be considered favorable in integrated pest management programs of this pest.

Synthon Approach in Crystal Engineering to Modulate Physicochemical Properties in Organic Salts of Chlorpropamide.

The formulation of drug with improved bioavailability is always challenging and indispensable in the field of pharmaceutics. The control of intermolecular interactions via crystal engineering approach and solid-state molecular recognition results in the formation of active drug molecules with modulated pharmacological benefits. Therefore, with the aim to improve the solubility and dissolution rate of the drug chlorpropamide (CPA), the mechanochemical liquid-assisted grinding (LAG) of the drug with several pharmaceutically accepted excipients was performed. This contributed to the discovery of six novel solid phases, namely salts, salt cocrystals and salt cocrystal hydrate─the salt of CPA with 3, 4-diaminopyridine (DAP); salt and salt cocrystal (SC) polymorph (Z″=3) with 1, 4-diazabicyclo [2.2.2] octane (DABCO); a salt, SC polymorph (Z″=9), and a SC hydrate (Z″=9) with piperazine (PIP). The formation of these salts and salt cocrystals are mainly guided by the strong hydrogen bonds with tunable strength having high electrostatic contribution. This attractive interaction brings the donor and the acceptor atoms close to each other for a facile proton transfer. Furthermore, the conformational constraints on the drug molecules, provided by the excipients via strong and directional hydrogen bonds, are quite impressive as this leads to the identification and characterization of "new conformational isomers" for the CPA molecules. The new crystalline phases exhibit enhanced intrinsic dissolution rate in comparison to that of the pure drug, the magnitude being 7, 131, and 120 folds for CPADAP, CPADABCO_II, and CPAPIP_III, respectively. Furthermore, it is interesting to note that the order of solubility is enhanced by 2.7-, 3-, and 7-fold, respectively, for the abovementioned salts. This also mirrors the trends in the magnitude of the binding energy, the higher magnitude being reflected in the lower solubility. Additionally, the in vivo experiments performed in SD rats results in the enhancement of the magnitude of the pharmacokinetic properties, when compared to the pristine drug. The concentration of the drug in CPADABCO_II and CPAPIP_III formulations exhibits 6- and 4-fold increments, respectively. Indeed, these results corroborate to the trends observed in the structural characterization, intermolecular energy calculations, solubility, and in vitro dissolution assessments.

Impact of temperature on the bionomics and geographical range margins of the two-spotted field cricket Gryllus bimaculatus in the world: Implications for its mass farming.

Gryllus bimaculatus (Orthoptera: Gryllidae) is widely considered an excellent nutrient source for food and feed. Despite its economic importance, there is limited information on the impact of temperature on the bionomics of this cricket to guide its effective and sustainable mass production in its geographical range. The biological parameters of G. bimaculatus were investigated at eight different temperatures ranging from 20-40˚C. The Insect Life-Cycle Modelling (ILCYM) program was used to fit linear and non-linear functions to the data to describe the influence of temperature on life history parameters and its farmability under the current and projected climate for 2050. Our results revealed that G. bimaculatus was able to complete its lifecycle in the temperature range of 20°C to 37°C with a maximum finite rate of population increase (= 1.14) at 35°C. The developmental time of G. bimaculatus decreased with increasing temperature. The least developmental time and mortality were attained at 32°C. The highest wet length and mass of G. bimaculatus occurred at 32°C. The lowest temperature threshold for G. bimaculatus egg and nymph development was approximated using linear regression functions to be at 15.9°C and 16.2°C with a temperature constant of 108.7 and 555.6 degree days. The maximum fecundity (2301.98 eggs per female), net reproductive rate (988.42 daughters/ generation), and intrinsic rate of natural increase (0.134 days) were recorded at 32°C and the shortest doubling of 5.2 days was observed at 35°C. Based on our findings G. bimaculatus can be farmed in countries with temperatures ranging between 20 and 37°C around the globe. These findings will help the cricket farmers understand and project the cricket population dynamics around the world as influenced by temperature, and as such, will contribute to more efficient farming.

The performance and physiological responses of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) to different sorghum cultivars

Utilizing pest-resistant cultivars is a highly effective and environmentally-friendly approach for managing crop infestations by pests. In the present study, the differences in the resistance of eight cultivars of Sorghum bicolor (L.) Moench (Kimia, Payam, Pegah, Sepideh, Spidfid, KGS23, KFS2, and KFS18) against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), a polyphagous pest of stored products, were evaluated based on demographic parameters, nutritional indices, and digestive enzymatic activities within the pest. The results revealed that the development time of R. dominica was the shortest when reared on Kimia, Spidfid, and KFS2, while the longest was recorded in those fed on Payam and Pegah. The fecundity of R. dominica was the lowest on Pegah. Furthermore, Kimia and Sepideh showed the highest intrinsic rate of increase (r) and finite rate of increase (λ), whereas the lowest values for these parameters were observed on Pegah and KGS23. The highest relative growth rate (RGR) of R. dominica was achieved on Sepideh, whereas the lowest RGR was observed on KGS23. The highest level of digestive proteolytic activity in R. dominica was observed on Sepideh, whereas the lowest level was found on KGS23. The amylolytic activity in R. dominica was the highest on Sepideh, and the lowest on Pegah and KGS23. The findings showed significant negative correlations between fecundity, intrinsic rate of increase, and amylolytic activity of the pest with the total phenolic content of the studied sorghum cultivars. Furthermore, the results obtained from cluster analysis revealed that Sepideh, Kimia, and KFS2 were the susceptible cultivars for population growth of R. dominica, while Payam, Pegah, and KGS23 were the partially resistant hosts for this pest. The pest-resistant sorghum cultivars identified in this study can potentially be utilized in combination with other pest control strategies for sustainable management of R. dominica, which may help reduce the excessive use of chemical insecticides.

Impacts of an expert’s opinion on the collective performance of a competing population for limited resources

The dissemination of information and opinion to the public has never been easier due to the easy access to platforms, making it necessary to study the responses to public information by a competing population. We study the impact of an expert’s opinion on the performance of a population including some die-hard fans of the expert and cautious agents who will adapt to trust or to ignore the expert’s opinion, within the framework of the minority game (MG). The expert collects information by probing a subpopulation for its minority opinion without the knowledge of its composition. When the information is not disseminated, the expert’s opinion has a higher accuracy than the intrinsic success rate of the population. When the information is disseminated, the population could enhance its success rate by making use of the wasted winning quotas through the actions of the fans and the adaptive ability of the cautious agents, as long as the fraction of the fans is not too big to turn the expert’s opinion into the losing option. There exists an optimal fraction of followers, the fans plus those cautious agents adapted to trust the expert, for the population to be the most harmonious with the highest success rate allowed by MG. The phenomena observed by numerical simulations motivated us to develop a theory, using the intrinsic success rate SrI, a quantity related to how the expert collects his information, and the average adapted level of trust f¯ among the cautious agents as inputs. The theory gives excellent agreement with simulation results, even when an approximated form of f¯ is invoked. The work paves the way for studying and formulating theories for the dissemination of other forms of information and opinion.

Enhancing LSCF-based air electrode durability: Insights into sulfur poisoning and air purification

The electrochemical performance of perovskite-type air electrodes in solid oxide cells is strongly affected by a trace amount of SO2 as the air impurity. The present work aims to study air purification efficiency in suppressing the degradation rate for the LSCF-GDC air electrode while operating under different SO2 concentrations. For this purpose, the electrochemical performance of symmetrical cells was evaluated using impedance spectra measured over 320 h and compared with intrinsic electrode degradation in synthetic air. Accordingly, the intrinsic degradation rate was measured at 0.05 mΩ cm2 h−1 while exposing the cell to synthetic air containing 10 and 100 ppb SO2, causing a severe increase to 0.17 and 0.30 mΩ cm2 h−1, respectively. Nevertheless, the calculated degradation rate under purified air containing 100 ppb SO2 was similar to the LSCF-GDC intrinsic degradation rate, representing the high practicality of filter material to adsorb SO2 species. Interpreting the impedance spectra using a distribution of relaxation times (DRT) and a complex nonlinear least squares fit (CNLS) revealed that the intrinsic degradation mechanisms were the limitation of dissociative surface adsorption of oxygen and charge transfer to the adsorbed oxygen. At the same time, inhibition of the O2 adsorption caused by the deposition of SrO, SO32−, and SrSO4 phases and increasing surface diffusion resistance for the adsorbed oxygen atoms were the rate-determining steps in SO2-containing synthetic air. Lastly, the effective suppression of degradation rate by gas purification indicates an extensive use of filter material to extend the lifespan of SOCs.

Insight into the synergistic effects of surface microstructures and wall peristalsis on glucose production in a bionic microreactor

The enzymatic hydrolysis stage is regarded as a key step in the production of biofuels derived from lignocellulosic biomass, but the elevated production expenses and limited conversion efficiency are still not favorable for practical applications. In this study, inspired by the efficient degradation of cellulose in the termite gut, a cellulase-loaded flexible microreactor model with bionic surface structures was first proposed for the production of fermentable glucose. In such a system, the fold-like structures can provide more enzyme loading sites, and villus-like structures can not only increase enzyme loading but also improve radial transfer in the microreactor. These two structures synergized well and resulted in a 58.5% increase in glucose production compared to the control. Applying peristalsis can further enhance mass transfer by the formation of backflow and vortex, and reducing the peristaltic period is more effective than increasing the peristaltic amplitude for glucose production enhancement. The glucose concentration obtained by the synergistic enhancement of peristalsis and surface structure was 2.3 times of the control. Moreover, for reactions with higher intrinsic reaction rates, the system is in a mass transfer-limited state and peristaltic enhancement is more effective. These results give insight into the design of the bionic flexible microreactor for efficient glucose production.

The effect of sublethal doses of flupyradifurone on the life table and esterase enzyme of Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae)

The aim of this study was to determine the effect of two different sublethal doses (LC10 and LC30) of flupyradifurone on the life table and esterase enzyme of Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae). The experiments were conducted in 2022 in Isparta University of Applied Sciences laboratory and climate rooms in 2022 as 1 control + 2 sublethal doses. For the life table, control, LC10 and LC30 doses were established as 30, 25 and 30 replications, respectively. Female and total lifespan of M. persicae adults exposed to LC10 concentrations of flupyradifurone were significantly shortened. Daily and total numbers of the offsprings decreased at both LC10 and LC30 concentrations. Furthermore, these negative effects on the aphid were revealed as a lower intrinsic rate of increase (r), net reproductive rate (R0), finite rate of increase (λ) and fecundity (F). Based on the obtained data, flupyradifurone seems to suppress the population growth of M. persicae. It was determined that esterase enzyme activity involved in pesticide detoxification did not change in populations exposed to two different sublethal doses of flupyradifurone and unexposed (control). It is thought that this study facilitates the understanding of the lethal and sublethal effects of flupyradifurone on aphid performance.

Enhanced dissolution of curcumin-resorcinol cocrystal by the inhibition effect of HPMCAS on solution-mediated phase transformation

The present study aimed to investigate the inhibition effect of polymers on the solution-mediated phase transformation (SMPT) of cocrystals during dissolution. Curcumin-resorcinol (CUR-RES) cocrystal was prepared by slow solvent evaporation, and the best precipitation inhibitor of curcumin (CUR) was selected from five polymers including hydroxypropyl methylcellulose acetate succinate (HPMCAS), hydroxypropyl methylcellulose (HPMC) E5, HPMC E50, Poloxamer 188 (P188) and polyethylene glycol (PEG) 6000 by solvent-shift precipitation test. Then non-sink dissolution tests and intrinsic dissolution rate (IDR) tests were performed with or without HPMCAS to explore the influence of HPMCAS on the dissolution of the cocrystal. It was showed that HPMCAS could effectively inhibit the crystallization of CUR so that the dissolved drug concentration in a predissolved 0.1 % HPMCAS solution at 2 h was nearly 15 μg/mL, which was at least 150 times higher than that without HPMCAS. The red CUR-RES cocrystal turned gradually to yellow CUR during the dissolution tests in the absence of HPMCAS, while the transformation was prevented in the presence of HPMCAS. The present work fully exploits the solubility advantages of CUR-RES cocrystal via the use of precipitation inhibitor and offers important insights into reducing the risk of SMPT during cocrystal dissolution, which is crucial for the development of pharmaceutical cocrystal formulations.