Abstract
Honey bee queen health is crucial for colony health and productivity, and pesticides have been previously associated with queen loss and premature supersedure. Prior research has ...investigated the effects of indirect pesticide exposure on queens via workers, as well as direct effects on queens during development. However, as adults, queens are in constant contact with wax as they walk on comb and lay eggs; therefore, direct pesticide contact with adult queens is a relevant but seldom investigated exposure route. Here, we conducted laboratory and field experiments to investigate the impacts of topical pesticide exposure on adult queens. We tested six pesticides commonly found in wax: coumaphos, tau-fluvalinate, atrazine, 2,4-DMPF, chlorpyriphos, chlorothalonil, and a cocktail of all six, each administered at 1, 4, 8, 16, and 32 times the concentrations typically found in wax. We found no effect of any treatment on queen mass, sperm viability, or fat body protein expression. In a field trial testing queen topical exposure of a pesticide cocktail, we found no impact on egg-laying pattern, queen mass, emergence mass of daughter workers, and no proteins in the spermathecal fluid were differentially expressed. These experiments consistently show that pesticides commonly found in wax have no direct impact on queen performance, reproduction, or quality metrics at the doses tested. We suggest that previously reported associations between high levels of pesticide residues in wax and queen failure are most likely driven by indirect effects of worker exposure (either through wax or other hive products) on queen care or queen perception.
Transition metal dichalcogenides (TMDs) have emerged as a new class of two-dimensional materials that are promising for electronics and photonics. To date, optoelectronic measurements in these ...materials have shown the conventional behavior expected from photoconductors such as a linear or sublinear dependence of the photocurrent on light intensity. Here, we report the observation of a new regime of operation where the photocurrent depends superlinearly on light intensity. We use spatially resolved photocurrent measurements on devices consisting of CVD-grown monolayers of TMD alloys spanning MoS2 to MoSe2 to show the photoconductive nature of the photoresponse, with the photocurrent dominated by recombination and field-induced carrier separation in the channel. Time-dependent photoconductivity measurements show the presence of persistent photoconductivity for the S-rich alloys, while photocurrent measurements at fixed wavelength for devices of different alloy compositions show a systematic decrease of the responsivity with increasing Se content associated with increased linearity of the current-voltage characteristics. A model based on the presence of different types of recombination centers is presented to explain the origin of the superlinear dependence on light intensity, which emerges when the nonequilibrium occupancy of initially empty fast recombination centers becomes comparable to that of slow recombination centers.
The synthesis and photophysical evaluation of two enatiomerially pure dimetallic lanthanide luminescent triple-stranded helicates is described. The two systems, formed from the chiral (R,R) ligand 1 ...and (S,S) ligand 2, were produced as single species in solution, where the excitation of either the naphthalene antennae or the pyridiyl units gave rise to Eu(III) emission in a variety of solvents. Excitation of the antennae also gave rise to circularly polarized Eu(III) luminescence emissions for Eu(2):1(3) and Eu(2):2(3) that were of equal intensity and opposite sign, confirming their enantiomeric nature in solution providing a basis upon which we were able to assign the absolute configurations of Eu(2):1(3) and Eu(2):2(3).
Abstract Poly(Styrene- block -IsoButylene- block -Styrene) (“SIBS”) is a biostable thermoplastic elastomer with physical properties that overlap silicone rubber and polyurethane. Initial data ...collected with SIBS stent-grafts and coatings on metallic stents demonstrate hemocompatibility, biocompatibility and long-term stability in contact with metal. SIBS has been used successfully as the carrier for a drug-eluting coronary stent; specifically Boston Scientific's TAXUS® stent, and its uses are being investigated for ophthalmic implants to treat glaucoma, synthetic heart valves to possibly replace tissue valves and other applications. At present, researchers developing medical devices utilizing SIBS have found the following: (1) SIBS does not substantially activate platelets in the vascular system; (2) polymorphonuclear leukocytes in large numbers are not commonly observed around SIBS implants in the vascular system or in subcutaneous implants or in the eye; (3) myofibroblasts, scarring and encapsulation are not clinically significant with SIBS implanted in the eye; (4) embrittlement has not been observed in any implant location; (5) calcification within the polymer has not been observed; and (6) degradation has not been observed in any living system to date. Some deficiencies of SIBS that need to be addressed include creep deformation in certain load-bearing applications and certain sterilization requirements. The reason for the excellent biocompatibility of SIBS may be due to the inertness of SIBS and lack of cleavable moieties that could be chemotactic towards phagocytes.
Honey bee populations in North America are an amalgamation of diverse progenitor ecotypes experiencing varying levels of artificial selection. Genetic differences between populations can result in ...variable susceptibility towards environmental stressors, and here we compared pesticide tolerances across breeding stocks using a mixture of seven pesticides frequently found in colonies providing pollination services. We administered the pesticide mixture chronically to in vitro reared larvae at four concentrations of increasing Hazard Quotient (HQ, or cumulative toxicity) and measured mortality during larval development. We found that different stocks had significantly different tolerances to our pesticide mixture as indicated by their median lethal toxicity (HQ50). The intensively selected Pol-Line stock exhibited the greatest pesticide sensitivity while Old World (progenitor) and putatively feral stocks were the most pesticide-tolerant. Furthermore, we found that activity of the detoxification enzyme esterase was positively correlated with pesticide tolerance when measured using two different substrate standards, and confirmed that larvae from the Pol-Line stock had generally lower esterase activity. Consistent with an increased pesticide tolerance, the Old World and putatively feral stocks had higher esterase activities. However, esterases and other detoxification enzymes (CYP450s and GSTs) were found in similar abundances across stocks, suggesting that the differences in enzyme activity we observed might arise from stock-specific single nucleotide polymorphisms or post-translational modifications causing qualitative variation in enzyme activity. These results suggest that selective breeding may inadvertently increase honey bees’ sensitivity to pesticides, whereas unselected, putatively feral and Old World stocks have larvae that are more tolerant.
•Honey bee colonies providing pollination services can accumulate pesticide residues.•We compared larval tolerance to a pesticide mixture across several breeding stocks.•Stock can influence larval pesticide tolerance and esterase activity.•The Pol-Line stock had the lowest pesticide tolerance and esterase activity.
Each year over 16 million older Americans undergo general anesthesia for surgery, and up to 40% develop postoperative delirium and/or cognitive dysfunction (POCD). Delirium and POCD are each ...associated with decreased quality of life, early retirement, increased 1-year mortality, and long-term cognitive decline. Multiple investigators have thus suggested that anesthesia and surgery place severe stress on the aging brain, and that patients with less ability to withstand this stress will be at increased risk for developing postoperative delirium and POCD. Delirium and POCD risk are increased in patients with lower preoperative cognitive function, yet preoperative cognitive function is not routinely assessed, and no intraoperative physiological predictors have been found that correlate with lower preoperative cognitive function. Since general anesthesia causes alpha-band (8-12 Hz) electroencephalogram (EEG) power to decrease occipitally and increase frontally (known as "anteriorization"), and anesthetic-induced frontal alpha power is reduced in older adults, we hypothesized that lower intraoperative frontal alpha power might correlate with lower preoperative cognitive function. Here, we provide evidence that such a correlation exists, suggesting that lower intraoperative frontal alpha power could be used as a physiological marker to identify older adults with lower preoperative cognitive function. Lower intraoperative frontal alpha power could thus be used to target these at-risk patients for possible therapeutic interventions to help prevent postoperative delirium and POCD, or for increased postoperative monitoring and follow-up. More generally, these results suggest that understanding interindividual differences in how the brain responds to anesthetic drugs can be used as a probe of neurocognitive function (and dysfunction), and might be a useful measure of neurocognitive function in older adults.
•Kinetics of methane adsorption in activated carbons AX-21 and TE7 and MOF MIL-101 are analysed.•Mass transfer coefficients, effective diffusivities and activation energies are calculated.•Enthalpies ...are estimated with Clausius-Clapeyron equation for absolute and excess adsorption.•These are compared with differential calorimetry, with differences up to 3.5kJmol−1.
Methane is touted as a replacement for fossil fuels in transport applications due to its lower costs of production and cleaner combustion. Storage of methane is still a problem and different technologies have been considered, including compression and liquefaction. Adsorption in a porous material is a potential alternative for methane storage, as it can increase densities at moderate pressures and temperatures. For practical applications, in addition to the quantities stored and working capacities, it is important to equally consider aspects such as kinetics of storage and thermal management of the storage system. In this paper, the kinetics and enthalpies of adsorption of methane in activated carbons AX-21 and TE7, and metal-organic framework MIL-101 (Cr) are extracted from readily available gas sorption data. The adsorption kinetics at 300K and 325K are analysed and fitted with the linear driving force (LDF) model, and mass transfer coefficients (MTC) and effective diffusivities are estimated. The effective diffusivities have a range of values from 1.79×10−13m2s−1 for the MIL-101 (Cr) at 300K to 9.36×10−10m2s−1 for the TE7 at 325K. The activation energies for the effective diffusivities based on an Arrhenius-type temperature dependence are calculated as 7.42, 7.09 and 5.38kJmol−1 for the AX-21, the MIL-101 (Cr) and the TE7, respectively. The enthalpies of adsorption are calculated with the Clausius-Clapeyron equation and the differences observed when calculating these with excess and absolute amounts are presented and discussed, with the results showing that enthalpies can have up to 10% differences if using excess amounts instead of absolute quantities. The isosteric enthalpies are also compared with enthalpies at zero-coverage obtained from differential calorimetry experiments for the MIL-101 (Cr), and a ∼3.5kJmol−1 difference is observed, which underlines the importance of refining calculation methods and bridging the gap between direct and indirect methods for calculating enthalpies of adsorption.
Drone honey bees (Apis mellifera) are the obligate sexual partners of queens, and the availability of healthy, high-quality drones directly affects a queen's fertility and productivity. Yet, our ...understanding of how stressors affect adult drone fertility, survival, and physiology is presently limited. Here, we investigated sex biases in susceptibility to abiotic stressors (cold stress, topical imidacloprid exposure, and topical exposure to a realistic cocktail of pesticides). We found that drones (haploid males) were more sensitive to cold and imidacloprid exposure than workers (sterile, diploid females), but the cocktail was not toxic at the concentrations tested. We corroborated this lack of cocktail toxicity with in-hive exposures via pollen feeding. We then used quantitative proteomics to investigate protein expression profiles in the hemolymph of topically exposed workers and drones, and found that 34 proteins were differentially expressed in exposed drones relative to controls, but none were differentially expressed in exposed workers. Contrary to our hypothesis, we show that drones express surprisingly high baseline levels of putative stress response proteins relative to workers. This suggests that drones' stress tolerance systems are fundamentally rewired relative to workers, and susceptibility to stress depends on more than simply gene dose or allelic diversity.
For men with high-risk localized prostate cancer, addition of docetaxel to androgen deprivation + external beam radiation did not improve survival. Chemotherapy as an adjuvant therapy does not result ...in clinical benefit for those with high-risk localized prostate cancer.
Intensification of therapy may improve outcomes for patients with high-risk localized prostate cancer.
To provide long-term follow-up data from phase III RTOG 0521, which compared a combination of androgen deprivation therapy (ADT) + external beam radiation therapy (EBRT) + docetaxel with ADT + EBRT.
High-risk localized prostate cancer patients (>50% of patients had Gleason 9–10 disease) were prospectively randomized to 2 yr of ADT + EBRT or ADT + EBRT + six cycles of docetaxel. A total of 612 patients were accrued, and 563 were eligible and included in the modified intent-to-treat analysis.
The primary endpoint was overall survival (OS). Analyses with Cox proportional hazards were performed as prespecified in the protocol; however, there was evidence of nonproportional hazards. Thus, a post hoc analysis was performed using the restricted mean survival time (RMST). The secondary endpoints included biochemical failure, distant metastasis (DM) as detected by conventional imaging, and disease-free survival (DFS).
After 10.4 yr of median follow-up among survivors, the hazard ratio (HR) for OS was 0.89 (90% confidence interval CI 0.70–1.14; one-sided log-rank p = 0.22). Survival at 10 yr was 64% for ADT + EBRT and 69% for ADT + EBRT + docetaxel. The RMST at 12 yr was 0.45 yr and not statistically significant (one-sided p = 0.053). No differences were detected in the incidence of DFS (HR = 0.92, 95% CI 0.73–1.14), DM (HR = 0.84, 95% CI 0.73–1.14), or prostate-specific antigen recurrence risk (HR = 0.97, 95% CI 0.74–1.29). Two patients had grade 5 toxicity in the chemotherapy arm and zero patients in the control arm.
After a median follow-up of 10.4 yr among surviving patients, no significant differences are observed in clinical outcomes between the experimental and control arms. These data suggest that docetaxel should not be used for high-risk localized prostate cancer. Additional research may be warranted using novel predictive biomarkers.
No significant differences in survival were noted after long-term follow-up for high-risk localized prostate cancer patients in a large prospective trial where patients were treated with androgen deprivation therapy + radiation to the prostate ± docetaxel.
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