Multi-resonant tessellated anchor-based metasurfaces

This is the final version. Available from Nature Research via the DOI in this record. Data availability: The research data supporting this publication are openly available from the University of Exeter’s institutional repository at: https://doi.org/10.24378/exe.4504.In this work, a multi-resonant metasurface that can be tailored to absorb microwaves at one or more frequencies is explored. Surface shapes based on an ‘anchor’ motif, incorporating hexagonal, square and triangular-shaped resonant elements, are shown to be readily tailorable to provide a targeted range of microwave responses. A metasurface consisting of an etched copper layer, spaced above a ground plane by a thin (<1/10th of a wavelength) low-loss dielectric is experimentally characterised. The fundamental resonances of each shaped element are exhibited at 4.1 GHz (triangular), 6.1 GHz (square) and 10.1 GHz (hexagonal), providing the potential for single- and multi-frequency absorption across a range that is of interest to the food industry. Reflectivity measurements of the metasurface demonstrate that the three fundamental absorption modes are largely independent of incident polarization as well as both azimuthal and elevation angles.Engineering and Physical Sciences Research Council (EPSRC)PepsiC

Microwave backscatter enhancement using radial anisotropy in biomimetic core-shell spheres

This is the final version. Available on open access from the American Institute of Physics via the DOI in this record.Data availability: The data that support the findings of this study are available from the corresponding authors upon reasonable request.Enhanced backscattering of microwave radiation is demonstrated experimentally in a biomimetic radially anisotropic spherical metamaterial component. The core-shell device replicates the optical function of nanospheres observed in the tapetum reflector of the compound eye of the shrimp Litopenaeus vannamei (Boone, 1931) and translates the effect from the optical domain to microwave frequencies. Analytical Mie theory calculations and numerical-method simulations are used to describe the origin of the observed scattering from a single dielectric sphere in terms of its multipolar Mie resonances. The fabrication of components using additive manufacture and their experimental characterization are described. The results show that the introduction of radial anisotropy in the shell more than doubles the monostatic radar cross section compared to the equivalent isotropic case. This work represents a practical demonstration of a synthetic bio-inspired structure, harnessing performance-enhancing adaptations that have evolved in nature. The results augment the range of techniques available for the control of electromagnetic scattering with relevance to applications in the manipulation of radar return signals.Engineering and Physical Sciences Research Council (EPSRC)Royal Academy of Engineerin

Complex permittivity and permeability of composite materials based on carbonyl iron powder over ultrawide frequency band

This is the final version. Available from the American Physical Society via the DOI in this record The complex electrical permittivity and magnetic permeability of composite materials made of a polymer binder filled with micron-scale carbonyl iron powder (CIP) are measured between 0.1 and 39 GHz. Permeability is measured in overlapping frequency subbands using two different techniques: a free-space method from 3 to 39 GHz and a coaxial impedance cell from 0.1 to 5 GHz. The dependence on filler concentration is studied for composites based on phosphated CIP R-100F-2. It is found that the static permittivity and permeability of the composites increase logarithmically with increasing percentage of CIP volume loading; this corresponds to Lichtenecker's law for a mixture of two components. It is demonstrated that by using the R-100F-2 type CIP it is possible to produce single-layer radar-absorbing materials with a relatively small thickness (less than 1.5 mm) and a deep and broad normal-incidence reflectivity minimum (less than -20 dB) from 10 to 30 GHz

Determinants of formation of aflatoxin-albumin adducts: a seven-township study in Taiwan

Dietary exposure to aflatoxins is one of the major risk factors for hepatocellular carcinoma. Individual susceptibility to aflatoxin-induced hepatocarcinogenesis may be modulated by both genetic and environmental factors affecting metabolism. A cross-sectional study was performed to evaluate determinants of the formation of aflatoxin covalently bound to albumin (AFB1-albumin adducts). A total of 474 subjects who were free of liver cancer and cirrhosis and were initially selected as controls for previous case–control studies of aflatoxin-induced hepatocarcinogenesis in Taiwan, were employed in this study. Aflatoxin-albumin adducts were determined by competitive enzyme-linked immunosorbent assay, hepatitis B surface antigen and antibodies to hepatitis C virus by enzyme immunoassay, as well as genotypes of glutathione S-transferase M1-1 and T1-1 by polymerase chain reaction. The detection rate of AFB1-albumin adducts was significantly higher in males (42.5%) than in females (21.6%) (multivariate-adjusted odds ratio=2.6, 95% confidence interval=1.4–5.0). The formation of detectable albumin adducts was moderately higher in hepatitis B surface antigen carriers (42.8%) than in non-carriers (36.6%) (multivariate-adjusted odds ratio=1.4, 95% confidence interval=1.0–2.1). In addition, the detection rate of AFB1-albumin adducts tended to increase with the increasing number of null genotypes of glutathione S-transferase M1-1 and glutathione S-transferase T1-1. In conclusion, this cross-sectional study has assessed the relative contributions of environmental exposure and host susceptibility factors in the formation of AFB1-albumin adducts in a well characterised Chinese adult population. This study further emphasises the necessity to reduce aflatoxin exposure in people living in an area endemic for chronic hepatitis B virus infection

Normative equations for central augmentation index:Assessment of inter-population applicability and how it could be improved

Common reference values of arterial stiffness indices could be effective screening tool in detecting vascular phenotypes at risk. However, populations of the same ethnicity may differ in vascular phenotype due to different environmental pressure. We examined applicability of normative equations for central augmentation index (cAIx) derived from Danish population with low cardiovascular risk on the corresponding Croatian population from the Mediterranean area. Disagreement between measured and predicted cAIx was assessed by Bland-Altman analysis. Both, cAIx-age distribution and normative equation fitted on Croatian data were highly comparable to Danish low-risk sample. Contrarily, Bland-Altman analysis of cAIx disagreement revealed a curvilinear deviation from the line of full agreement indicating that the equations were not equally applicable across age ranges. Stratification of individual data into age decades eliminated curvilinearity in all but the 30–39 (men) and 40–49 (women) decades. In other decades, linear disagreement independent of age persisted indicating that cAIx determinants other than age were not envisaged/compensated for by proposed equations. Therefore, established normative equations are equally applicable to both Nordic and Mediterranean populations but are of limited use. If designed for narrower age ranges, the equations’ sensitivity in detecting vascular phenotypes at risk and applicability to different populations could be improved

Use of Confocal Laser as Light Source Reveals Stomata-Autonomous Function

In most terrestrial plants, stomata open during the day to maximize the update of CO(2) for photosynthesis, but they close at night to minimize water loss. Blue light, among several environmental factors, controls this process. Stomata response to diverse stimuli seems to be dictated by the behaviour of neighbour stomata creating leaf areas of coordinated response. Here individual stomata of Arabidopsis leaves were illuminated with a short blue-light pulse by focusing a confocal argon laser. Beautifully, the illuminated stomata open their pores, whereas their dark-adapted neighbours unexpectedly experience no change. This induction of individual stomata opening by low fluence rates of blue light was disrupted in the phototropin1 phototropin2 (phot1 phot2) double mutant, which exhibits insensitivity of stomatal movements in blue-illuminated epidermal strips. The irradiation of all epidermal cells making direct contact with a given stoma in both wild type and phot1 phot2 plants does not trigger its movement. These results unravel the stoma autonomous function in the blue light response and illuminate the implication of PHOT1 and/or PHOT2 in such response. The micro spatial heterogeneity that solar blue light suffers in partially shaded leaves under natural conditions highlights the physiological significance of the autonomous stomatal behaviour

First observations of separated atmospheric nu_mu and bar{nu-mu} events in the MINOS detector

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nuµ and [overline nu ]µ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving Rup/downdata/Rup/downMC=0.62-0.14+0.19(stat.)±0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nuµ and [overline nu ]µ interactions are separated. The ratio of [overline nu ]µ to nuµ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R[overline nu ][sub mu]/nu[sub mu]data/R[overline nu ][sub mu]/nu[sub mu]MC=0.96-0.27+0.38(stat.)±0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nuµ and [overline nu ]µ

Piroxicam and intracavitary platinum-based chemotherapy for the treatment of advanced mesothelioma in pets: preliminary observations

Malignant Mesothelioma is an uncommon and very aggressive tumor that accounts for 1% of all the deaths secondary to malignancy in humans. Interestingly, this neoplasm has been occasionally described in companion animals as well. Aim of this study was the preclinical evaluation of the combination of piroxicam with platinum-based intracavitary chemotherapy in pets. Three companion animals have been treated in a three years period with this combination. Diagnosis was obtained by ultrasonographic exam of the body cavities that evidenced thickening of the mesothelium. A surgical biopsy further substantiated the diagnosis. After drainage of the malignant effusion from the affected cavity, the patients received four cycles of intracavitary CDDP at the dose of 50 mg/m2 every three weeks if dogs or four cycles of intracavitary carboplatin at the dose of 180 mg/m2 (every 3 weeks) if cats, coupled with daily administration of piroxicam at the dose of 0.3 mg/kg. The therapy was able to arrest the effusion in all patients for variable remission times: one dog is still in remission after 3 years, one dog died of progressive disease after 8 months and one cat died due to progressive neoplastic growth after six months, when the patient developed a mesothelial cuirass. The combination showed remarkable efficacy at controlling the malignant effusion secondary to MM in our patients and warrants further investigations