Probing Behavior Research Articles

On the non-flatness nature of noncommutative Minkowski spacetime and the singular behavior of probes

It is more than a century-old concept that the Minkowski spacetime is flat. From the pure geometric point of view, we explicitly address the issue of whether a noncommutative Minkowski spacetime is flat or not. In the framework of the twisted-diffeomorphism approach to noncommutative gravity with canonical type noncommutative (NC) coordinate structure, one important result that we get is that the NC Minkowski spacetime parametrized either with spherical polar coordinates or with parabolic coordinates has nontrivial NC corrections to Riemann curvature tensor, Ricci tensor and curvature scalars. Another crucial result is that the curvature scalars have singular behavior at certain points, and these singularities are not coordinate singularities. The nature of these singularities clearly points towards the idea of high-energetic probes turning into black holes. The absence of any such noncommutative corrections, and thus any such singularities, in the cases of Cartesian coordinates and cylindrical coordinates leads to the conclusion that high-energetic probes do not turn into black holes when the canonical NC structure is considered for these coordinates.

Cyanide and chloroform detection through J-aggregates based aggregation induced emission probe with real sample applications

Isopthalamide based probe DPI has been synthesized by an easy two-step substitution reaction. Unique fluorescence properties of probe DPI were exploited for sensing of CNˉ and chloroform. Various spectroscopic techniques such as NMR, LC-MS, SEM, DLS, UV-Vis. and fluorescence spectroscopy in combination with DFT studies were used to confirm efficient detection of CN‾ through a non-covalent interaction of cyanide with probe. Furthermore, probe showed fluorescence emission at 360 nm which shifted significantly to 415 nm upon addition of water exhibiting unique AIE characteristics and formation of desired J-aggregates. Mechanistically, CN‾ and chloroform were selectively detected through fluorescence quenching with 9 nM and 0.2 % v/v limit of detection (LOD), respectively. Photoinduced electron transfer (PET) was proven to be involved as a sensing mechanism. Moreover, DPI exhibited interesting solvatochromism properties. DPI was proven to be a highly sensitive probe which showed solid-state and vapor phase on-field detection of CN‾. Similar sensing behavior of DPI probe towards CN‾ was seen in food and water samples.

Photochemical and electrochemical behavior of a molecular probe: Fluorescence on-off-on response to detect multiple ions (Cu2+, ClO− and CN−) with different rate of reaction

A molecular probe 3 containing phenyl substituted imidazolyl unit and diaminomaleonitrile (DAMN) moiety has been synthesized and characterized. Photophysical and electrochemical behavior probe 3 were studied in partial aqueous medium (ACN/H2O, 9.5:0.5 v/v). Probe 3 upon interaction with different class of ions showed sensitivity for Cu2+, ClO− and CN− ions with different response time and reaction rates due to variation in intramolecular charge transfer (ICT) process. Both Cu2+ and ClO− ions displayed enhanced emission due to hydrolysis of imine bond to form compound 2 in the medium whereas, with CN− fluorescence quenching was observed due to the deprotonation of –OH/–NH2 functions. The kinetic and optical behavior of the probe suggested that interaction occurred in two steps with Cu2+ (complexation and hydrolysis; absk1,2,3(Cu2+) = 1.17, 0.74 and 0.06 s−1) and ClO− (hydrolysis and deprotonation; absk1,2(ClO−) = 3.0 and 0.60 s−1) ions while CN− (absk1,2(CN−) = 2.13 and 1.66 s−1) induces deprotonation in one step. The interaction of probe 3 with ClO− was relatively fast than with Cu2+/CN− ions. Job's plot analysis between probe 3 and ions revealed a 1:1 (Cu2+/ClO−) and 1:2 (CN−) ratio stoichiometry with good limit of detection (nM) and binding affinity (LOD, 17; KCu2+ = 3.23 × 106 M−1; LOD, 18.5; KClO− = 5.23 × 105 M−1 and LOD, 23.2; KCN− = 5.50 × 109 M−2) respectively. Probe 3 displayed a naked–eye sensitive fluorescence response to detect tested ions on test paper strips and good recovery percentage of ions in real water sample analysis.

Microdroplet-SERS platform for single cell-secreted VEGF and extracellular pH analysis in oxidative stress event

Although oxidative stress processes based on reactive oxygen species have been the research focus, analyzing this phenomenon at the single-cell level is challenging. A microfluidic platform combined with highly sensitive surface-enhanced Raman scattering (SERS) technology was constructed. The secretion of the vascular endothelial growth factor (VEGF) and the extracellular microenvironmental pH fluctuations of a single cell during the oxidative stress process were assessed and analyzed. The immune sandwich structure formed between the capture probe and the reporter probe with the linkage of secreted VEGF was built above the probed cell surface in each drop. The self-driven collection behavior of the magnetic bead-based capture probe toward the cell surface significantly amplified the SERS signals of the reporter probe, thus improving the sensitivity and accuracy of detection. 4-Mercaptopyridine (4-Mpy) responding sensitively to pH was applied to label the reporter probe, which endows the extracellular microenvironmental pH sensing during oxidative stress events according to relative SERS intensity. Combined with machine learning to analyze the spectral characteristics, the distinction between normal cells and different types of tumor cells was finally realized. This study makes full use of the advantages of machine learning to process spectral data to explore deep information and provides an auxiliary tool for diagnosing cancer and other medical conditions in the future.

Identification and Evaluation of Sugarcane Cultivars for Antixenosis Resistance to the Leafhopper Yamatotettix flavovittatus Matsumura (Hemiptera: Cicadellidae).

Understanding the settling preference, feeding behavior, honeydew production, and biophysical factors, such as trichome density, related to Y. flavovittatus leafhopper infestation in sugarcane cultivation is crucial for effective pest management strategies. This study investigated these aspects across nine sugarcane cultivars. Significant variability was observed among cultivars in terms of settling behavior, with KK3 and LK92-11 showing the highest number of settled leafhopper adults. Similarly, honeydew production varied significantly among cultivars, with KK3 and LK92-11 exhibiting the highest production. Employing the electrical penetration graph (EPG) technique provided insights into distinct probing behaviors across cultivars, highlighting correlations between settling preference, honeydew production, and specific EPG waveforms. Principal component analysis (PCA) categorized cultivars into four groups based on settling preference, honeydew production, feeding behavior, and biophysical factors. Strong correlations were found between settling preference, honeydew production, and various EPG waveforms, while negative correlations were observed with the number of silica cells and rows per unit area, indicating their potential role in deterring leafhopper settlement. We concluded that TPJ04-768 and K84-200 are promising for resistance against leafhoppers and, thereby, can be exploited in sugarcane breeding programs with regard to resistance against insects.

2-Amino-4-chlorophenol based Schiff base allied organosilatrane and its silica nanoparticles: Sensing of Cu(II) ion and urease inhibitory activity via spectroscopic and molecular docking study

In this manuscript, 2-amino-4-chlorophenol based Schiff base allied organosilatrane was synthesized using click silylation approach. Then, an astonishing movement was made by encapsulation of compound 5 over silica nanoparticles (Si-NPs) to synthesize hybrid silica nanoparticles acknowledged as AP-NPs and were characterized through various techniques. The colorimetric as well as UV–Vis absorption studies were carried out to recognize the sensing behavior of probes 5 and AP-NPs towards array of metal ions. The probes 5 and AP-NPs detected Cu2+ ion across wide range of other co-existent metal ions recommending highly selective nature. Further, the possible binding modes between ligand 5 and CuCl2 were inspected experimentally through FT-IR and also, approved theoretically by DFT. Moreover, the molecular docking studies were performed to rationalize the highly preferred modes of interaction of ligand 5 with active site of urease.

Variable foraging and flower probing behaviour of sunbird pollinators of the South African Pelargonium fulgidum

ABSTRACT Whether foraging sunbird pollinators hover or perch, the type of perch used, and the direction of flower probing are generally thought to be determined by matching shapes of decurved bird bills and curved flower tubes, as well as inflorescence architecture. However, few studies have objectively quantified aspects of sunbird foraging behaviour to test predictions based on adaptive trait matching. I investigated sunbird foraging in a population of Pelargonium fulgidum, a species with slightly upcurved flowers borne on upward-oriented peduncles, which grows along the west coast of South Africa. Long-range photographs revealed that Cinyris chalybeus, a sunbird species with a slightly decurved bill, hovers or perches during foraging, and uses both the inflorescence and alternative vegetation structures as perch. Contrary to previous suggestions, both male and female sunbirds probe flowers from either of two alternative directions (sternotribic versus nototribic) in more or less equal proportions, and frequently display flexibility in both foraging behaviour and flower probing direction. Predominant or complete sternotribic and nototribic flower probing were explained by hovering versus use of an inflorescence perch respectively, whereas use of an alternative perch resulted in similar proportions of each mode of flower probing. The number of flowers per visited inflorescence and number and proportion of probed flowers did not vary with foraging behaviour or flower probing direction. Although certain foraging behaviours resulted in predictable flower probing directions, variation in foraging behaviour and the presence of many alternative perches provided by vegetation surrounding P. fulgidum plants resulted in variability in flower probing direction that appears not to affect foraging efficiency. Relatively weak reciprocal curvature of flower tube and sunbird bill, resulting in easy access to nectar from multiple feeding directions, likely facilitates flexible foraging. This study shows that environmental context may facilitate more complex foraging behaviour than that predicted by adaptive trait matching.

The effect of repeat feeding on dengue virus transmission potential in Wolbachia-infected Aedes aegypti following extended egg quiescence.

As Wolbachia pipientis is more widely being released into field populations of Aedes aegypti for disease control, the ability to select the appropriate strain for differing environments is increasingly important. A previous study revealed that longer-term quiescence in the egg phase reduced the fertility of mosquitoes, especially those harboring the wAlbB Wolbachia strain. This infertility was also associated with a greater biting rate. Here, we attempt to quantify the effect of this heightened biting behavior on the transmission potential of the dengue virus using a combination of assays for fitness, probing behavior, and vector competence, allowing repeat feeding, and incorporate these effects in a model of R0. We show that Wolbachia-infected infertile mosquitoes are more interested in feeding almost immediately after an initial blood meal relative to wild type and Wolbachia-infected fertile mosquitoes and that these differences continue for up to 8 days over the period we measured. As a result, the infertile Wolbachia mosquitoes have higher virus prevalence and loads than Wolbachia-fertile mosquitoes. We saw limited evidence of Wolbachia-mediated blocking in the disseminated tissue (legs) in terms of prevalence but did see reduced viral loads. Using a previously published estimate of the extrinsic incubation period, we demonstrate that the effect of repeat feeding/infertility is insufficient to overcome the effects of Wolbachia-mediated blocking on R0. These estimates are very conservative, however, and we posit that future studies should empirically measure EIP under a repeat feeding model. Our findings echo previous work where periods of extensive egg quiescence affected the reproductive success of Wolbachia-infected Ae. aegypti. Additionally, we show that increased biting behavior in association with this infertility in Wolbachia-infected mosquitoes may drive greater vector competence. These relationships require further exploration, given their ability to affect the success of field releases of Wolbachia for human disease reduction in drier climates where longer egg quiescence periods are expected.

Population dynamics, feeding strategies, and coccinellid predators of the larch woolly adelgid exules on the European larch

The larch woolly adelgid Adelges laricis Vallot (Hemiptera: Adelgidae) infests spruce Picea spp. and larch Larix spp. in the Northern Hemisphere. The present field and laboratory research embraced the hitherto unknown aspects of the biology and ecology of A. laricis on its secondary host, the European larch Larix decidua Mill. in Poland. The study showed that the A. laricis population on L. decidua was represented by exulis sistens females at dwarf stem bases, exulis progrediens mobile 1st instar nymphs (crawlers) on needles, exulis progrediens sessile “woolly” nymphs and “woolly” adults on needles, and winged sexupara females. The maximum abundance of the A. laricis population occurred from the end of April until mid-May, which coincided with the predomination of crawlers in the age structure of the population. The most important limiting weather component was high rainfall, affecting mainly the crawlers. Eight species of Coccinellidae were recorded on adelgid-infested larch trees and Exochomus quadripustulatus (L.) was the dominant species. The main differences in food consumption strategies among adelgid developmental stages were related to the duration of phloem sap ingestion. While the total duration of sap consumption at a given time was similar in all adelgid instars studied, the individual bouts of sap ingestion were much shorter in crawlers than in the sessile forms. The specific probing behavior of the mobile nymphs probably reflects the crawlers’ strategy to evaluate plant sap quality in different phloem vessels. It is likely that such strategy is a behavioral preadaptation for finding abundant food sources for permanent settling before crawlers develop into sessile nymphs and adult females. The feeding strategy of crawlers promotes the rapid dispersal of the population. Therefore, the control of A. laricis on L. decidua should focus on the early stages of the population development, which would most effectively reduce the final damage.

Adaptation of feeding behaviors on two Brassica species by colonizing and noncolonizing Bemisia tabaci (Hemiptera: Aleyrodidae) NW whiteflies.

Bemisia tabaci New World (NW)(Gennadius) (Hemiptera: Aleyrodidae), a whitefly in the B. tabaci species complex, is polyphagous on many plant species. Yet, it has been displaced, albeit not entirely, by other whitefly species. Potential causes could include issues with adaptation, feeding, and the colonization of new-hosts; however, insights that would help clarify these possibilities are lacking. Here, we sought to address these gaps by performing electropenetrography (EPG) recordings of NW whiteflies, designated "Napus" and "Rapa," reared on 2 colony hosts, Brassica napus and B. rapa, respectively. Analysis of 17 probing and pathway (pw) phase-related EPG variables revealed that the whiteflies exhibited unique probing behaviors on their respective colony hosts, with some deterrence being encountered on B. rapa. Upon switching to B. rapa and B. napus, the probing patterns of Napus and Rapa whiteflies, respectively, adapted quickly to these new-hosts to resemble that of whiteflies feeding on their colony hosts. Results for 3 of the EPG variables suggested that B. rapa's deterrence against Napus whitefly was significant prior to the phloem phase. This also suggested that adaptation by Rapa whitefly improved its pw probing on B. rapa. Based on analysis of 24 phloem phase-related EPG variables, Napus and Rapa whiteflies performed equally well once they entered phloem phase and exhibited comparable phloem acceptability on both the colony- and new-hosts. These findings demonstrate that NW whiteflies reared on a colony host are highly adaptable to feeding on a new host despite encountering some deterrence during the nonphloem phases in B. rapa plant.

Impact of biopesticides on the probing and feeding behavior of Aphis gossypii

BackgroundPesticides-induced mortality has traditionally been the toxicological endpoint on which a chemical is selected for pest management strategies. However, the exposure to a pesticide might also cause behavioral alterations that can dramatically affect the dynamics of pest-plant interaction. Understanding these non-lethal effects is crucial for developing comprehensive and sustainable pest control measures.MethodsHere, using the Electrical Penetration Graph (EPG) technique, we evaluated whether biopesticides routinely used in organic or conventional pest management might alter the probing and feeding behavior of the cotton aphid Aphis gossypii on treated plants. The post exposure persistence of feeding alterations when moving the insect onto clean plants was also assessed. The tested biopesticides were chosen for being aphicides or because used in those crops hosts of A. gossypii. Generalised linear mixed models were fitted to analyse the effects of biopesticides on the probing and feeding behavior of aphids, using untreated control data as a model baseline.ResultsResiduals of Bacillus thuringiensis, Beauveria bassiana, and sulfur significantly affected the dynamics of the stylets intercellular route compared to the control (namely, shorter pathways, fewer and shorter brief intracellular stylets probes, higher and longer derailed stylets events). Mineral oil, orange essential oil and pyrethrin delayed or impaired the onset of phloem sap ingestion. On the other hand, copper and potassium salts promoted feeding. Pyrethrin was the only biopesticides inducing persistent behavioral alterations, with insects displaying a higher frequency of occurrence of xylem ingestion events when moved to untreated plants after exposure.ConclusionsOverall, this study demonstrates that biopesticides modulate the aphid-plant interactions by impairing or facilitating the exploitation of the host plant, also affecting the patterns conducive to plant pathogens transmission. This study also highlights the importance of considering in toxicological studies the impact of all the compounds the pest could be exposed to within the agroecosystem, including those not designed for that specific pest.

Effect of Microhydration in Tuning the Photophysical Behavior of a Luminescent DNA Probe Revealed by Non‐Adiabatic Dynamics

AbstractWe report non‐adiabatic dynamics, performed in the surface hopping formalism, of 2‐thienyl‐3‐hydroxychromone, an environment‐dependent luminescent organic DNA probe. In particular we have shown that the first shell solvent water molecules undergo a rather complex reorganization upon light excitation. This involves also the triggering of a water‐mediated proton transfer process which leads to the formation of the tautomeric structure. The presence of this solvent‐mediated transfer mechanism globally diminishes the intersystem crossing efficiency, and hence the population of the triplet state manifold, as compared to the non‐solvated systems. Our results also point out the non‐innocent role of solvent networks in tuning complex photophysical processes, while opening competitive relaxation channels.

Flow-based bioconjugation of coumarin phosphatidylethanolamine probes: Optimised synthesis and membrane molecular dynamics studies

A series of phosphatidylethanolamine fluorescent probes head-labelled with 3-carboxycoumarin was prepared by an improved bioconjugation approach through continuous flow synthesis. The established procedure, supported by a design of experiment (DoE) set-up, resulted in a significant reduction in the reaction time compared to the conventional batch method, in addition to a minor yield increase. The characterization of these probes was enhanced by an in-depth molecular dynamics (MD) study of the behaviour of a representative probe of this family, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine labelled with 3-carboxycoumarin (POPE-COUM), in bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (SLPC) 2:1, mimicking the composition of the egg yolk lecithin membranes recently used experimentally by our group to study POPE-COUM as a biomarker of the oxidation state and integrity of large unilamellar vesicles (LUVs). The MD simulations revealed that the coumarin group is oriented towards the bilayer interior, leading to a relatively internal location, in agreement with what is observed in the nitrobenzoxadiazole fluorophore of commercial head-labelled NBD-PE probes. This behaviour is consistent with the previously stated hypothesis that POPE-COUM is entirely located within the LUVs structure. Hence, the delay on the oxidation of the probe in the oxygen radical absorbance capacity (ORAC) assays performed is related with the inaccessibility of the probe until alteration of the LUV structure occurs. Furthermore, our simulations show that POPE-COUM exerts very little global and local perturbation on the host bilayer, as evaluated by key properties of the unlabelled lipids. Together, our findings establish PE-COUM as suitable fluorescent lipid analogue probes.

Synthesis of Schiff‐Base Allied Silanes for the Photophysical Detection of Cr(III) Ion And In‐Silico Staphylococcus Aureus Inhibiting Activity

AbstractChromium is known to play an important role in various metabolic pathways; however, its excessive use can result in negative impact on mankind, this necessitates the development of sensors for Cr(III) ion. The current study has incorporated the synthesis of ether derived Schiff base allied silanes 4 a–4 d, which have been characterized using 1H NMR, 13C NMR and mass spectrometry. The spectroscopic technique of UV‐visible has been utilized to study the sensing behaviour of probe 4 a, resulting in a good sensing ability towards Cr(III) ion, yielding a detection limit of 4.2×10−7 M and an association constant value of 2.25×106 M−1. In order to study the stoichiometric binding between probe and metal ion, Job's plot method has been employed which shows 1 : 1 binding ratio. The mechanism of binding has been studied via 1H NMR, UV‐visible, FT‐IR spectroscopy and mass spectrometry. The binding has been further supported by DFT. The real sample analysis has been performed to validate the utility of the synthesized sensor in practical applications. The theoretical tool of molecular docking has been considered to study the protein‐ligand interaction between S. aureus bacterial protein and ligand 4 a, yielding a value of −7.63 kcal/mol for binding energy.

Hesperidin as a Species-Specific Modifier of Aphid Behavior.

Hesperidin is a highly bioactive natural flavonoid whose role in ecological interactions is poorly known. In particular, the effects of hesperidin on herbivores are rarely reported. Flavonoids have been considered as prospective biopesticides; therefore, the aim of the present study was to examine the influence of hesperidin on the host plant selection behavior of three aphid (Hemiptera: Aphididae) species: Acyrthosiphon pisum Harrris, Rhopalosiphum padi (L.), and Myzus persicae (Sulz.). The aphid host plants were treated with 0.1% and 0.5% ethanolic solutions of hesperidin. Aphid probing behavior in the no-choice experiment was monitored using electropenetrography and aphid settling on plants in the choice experiment was recorded. The results demonstrated that hesperidin can be applied as a pre-ingestive, ingestive, and post-ingestive deterrent against A. pisum, as an ingestive deterrent against R. padi, and as a post-ingestive deterrent against M. persicae using the relatively low 0.1% concentration. While in A. pisum the deterrent effects of hesperidin were manifested as early as during aphid probing in peripheral plant tissues, in M. persicae, the avoidance of plants was probably the consequence of consuming the hesperidin-containing phloem sap.

Salivary proteins NlSP5 and NlSP7 are required for optimal feeding and fitness of the brown planthopper, Nilaparvata lugens.

Saliva has a crucial role in determining the compatibility between piercing-sucking insects and their hosts. The brown planthopper (BPH) Nilaparvata lugens, a notorious pest of rice in East and Southeast Asia, secretes gelling and watery saliva when feeding on rice sap. Nlsalivap-5 (NlSP5) and Nlsalivap-7 (NlSP7) were identified as potential planthopper-specific gelling saliva components, but their biological functions remain unknown. Here, we showed by transcriptomic analyses that NlSP5 and NlSP7 were biasedly expressed in the salivary glands of BPHs. Using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome-editing system, we constructed NlSP5 and NlSP7 homozygous mutants (NlSP5-/- and NlSP7-/-). Electrical penetration graph assay showed that NlSP5-/- and NlSP7-/- mutants exhibited abnormal probing and feeding behaviors. Bioassays revealed that the loss-of-function of NlSP5 and NlSP7 significantly reduced the fitness of BPHs, with extended developmental duration, shortened lifespan, reduced weight, and impaired fecundity and hatching rates. These findings deepen our understanding of the BPH-host interaction and may provide potential targets for the management of rice planthoppers. © 2024 Society of Chemical Industry.

Molecular Gas Tracers in Young and Old Protoplanetary Disks

Molecular emission is used to investigate both the physical and chemical properties of protoplanetary disks. Therefore, to derive disk properties accurately, we need a thorough understanding of the behavior of the molecular probes upon which we rely. Here we investigate how the molecular line emission of N2H+, HCO+, HCN, and C18O compare to other measured quantities in a set of 20 protoplanetary disks. Overall, we find positive correlations between multiple line fluxes and the disk dust mass and radius. We also generally find strong positive correlations between the line fluxes of different molecular species. However, some disks do show noticeable differences in the relative fluxes of N2H+, HCO+, HCN, and C18O. These differences occur even within a single star-forming region. This results in a potentially large range of different disk masses and chemical compositions for systems of similar age and birth environment. While we make preliminary comparisons of molecular fluxes across different star-forming regions, more complete and uniform samples are needed in the future to search for trends with birth environment or age.

Detection of copper in tea and water sample: A click-oriented azomethine-based 1,2,3-triazole fluorescent chemosensor with reversible INHIBIT logic gate behavior and computational aspects

A fluorescent azomethine-scaffolded-1,2,3-triazole linked chemosensor was synthesized utilizing alkyne and azidomethylbenzene via Cu(I)-catalyzed click chemistry. The compounds (3–5 and L6) were analyzed using FTIR, 1H NMR, 13C NMR, and GCMS–. The exploration of ion sensing ability of L6 complex, using UV–Vis and fluorescence spectroscopy in ACN:H2O (4:1) medium resulted in detection of Cu(II) ions, exclusively. Further L6-Cu(II) complex was characterized via FTIR, FE-SEM, LCMS and supported by DFT studies. A significant structural modification has rendered the current probe as highly selective for Cu2+ ions, with ‘Turn-On’ response. The chemical receptor (L6) establishes 1:1 molar ratio with Cu(II) ions with binding constant of 6.0 × 104 M−1 and excellent detection limit of 20 nM. In addition, the sensitive reversible behavior of probe (L6) with two chemical inputs (Cu2+ and EDTA) contributes to the construction of an INHIBIT logic circuit. The Copper ion detection was effectively monitored for real-world samples like Black Tea with precise quantification of Copper(II) ions.

Application of electron paramagnetic resonance spectroscopy for determining the relative nanoenvironment fluidity of polymeric micelles.

Polymeric micelles are nanocarriers for drug, protein and gene delivery due to their unique core/shell structure, which encapsulates and protects therapeutic cargos with diverse physicochemical properties. However, information regarding the micellar nanoenvironment's fluidity can provide unique insight into their makeup. In this study, we used electron paramagnetic resonance (EPR) spectroscopy to study free radical spin probe (5-doxylstearate methyl ester, 5-MDS, and 16-doxylstearic acid, 16-DS) behaviour in methoxy-poly(ethylene oxide)-poly(α-benzyl carboxylate-ε-caprolactone) (PEO-PBCL) and methoxy-poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) polymeric micelles. Spin probes provided information about the spectroscopic rotational correlation time (τ, s) and the spectroscopic partition parameter F. We hypothesized that spin probes would partition into the polymeric micelles, and these parameters would be calculated. The results showed that both 5-MDS and 16-DS spectra were modulated in the presence of polymeric micelles. Based on τ values, 5-MDS revealed that PEO-PCL (τ = 3.92 ± 0.26 × 10-8s) was more fluid than PEO-PBCL (τ = 7.15 ± 0.63 × 10-8s). The F parameter, however, could not be calculated due to the rotational hindrance of the probe within the micelles. With 16-DS, more probe rotation was observed, and although the F parameter could be calculated, it was not helpful to distinguish the micelles' fluidity. Also, doxorubicin-loading interfered with the spin probes, particularly for 16-DS. However, using simulations, we could distinguish the hydrophilic and hydrophobic components of the 16-DS probe. The findings suggest that EPR spectroscopy is a valuable method for determining core fluidity in polymeric micelles.

The Effect of Essential Oils from Asteraceae Plants on Behavior and Selected Physiological Parameters of the Bird Cherry-Oat Aphid.

Essential oils (EOs), including those from the Asteraceae plants, have been shown to have promising insecticidal activity against a wide range of insect pests. Understanding the mechanism of action of EOs is one of the studied aspects. The present study aimed to evaluate the effect of essential oils from Achillea millefolium, Santolina chamaecyparissus, Tagetes patula and Tanacetum vulgare on the settling and probing behavior of the bird cherry-oat aphid (Rhopalosiphum padi L.). In addition, the effect of the oils on the activity of such enzymes as trypsin, pepsin and α- and β-glucosidase involved in the metabolism of proteins and sugars of the insects was examined. The leaf-choice bioassays demonstrated that the studied EOs limited aphid settling for at least 24 h after the treatment. The application of EOs also inferred with aphid probing behavior by reducing the total probing time and total duration of phloem sap ingestion. Aphids spent more time in the search phase due to an increase in the number and total duration of pathway phases. Moreover, the activity of the studied proteases and glucosidases significantly decreased in R. padi females exposed to the EOs. The enzyme inhibition varied depending on the applied oil and exposure time. Generally, the EOs with stronger deterrent activity also showed higher inhibitory effects. The results suggest that the tested EOs disrupt key digestive processes in R. padi which may be an important factor determining their aphicidal activity.