Perspectives on weak interactions in complex materials at different length scales.

Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a super-structure, which can be designed to create material properties targeted for specific applications. For electromagnetism, such targeted properties include field enhancements around the bandgap of a semiconductor used for solar cells, directional decay in topological insulators, high kinetic inductance in superconducting circuits, and many more. Despite very different application areas, all of these properties are united by the common aim of exploiting collective interaction effects between quantum objects. The literature on the topic spreads over very many different disciplines and scientific communities. In this review, we present a cross-disciplinary overview of different approaches for the creation, analysis and theoretical description of nanocomposites with applications related to electromagnetic properties.

Temperature-Dependent Bending Rigidity of AB-Stacked Bilayer Graphene.

The change in bending rigidity with temperature κ(T) for 2D materials is highly debated: theoretical works predict both increase and decrease. Here we present measurements of κ(T), for a 2D material: AB-stacked bilayer graphene. We obtain κ(T) from phonon dispersion curves measured with helium atom scattering in the temperature range 320-400 K. We find that the bending rigidity increases with temperature. Assuming a linear dependence over the measured temperature region we obtain κ(T)=[(1.3±0.1)+(0.006±0.001)T/K] eV by fitting the data. We discuss this result in the context of existing predictions and room temperature measurements.

Erratum: Bending Rigidity of 2D Silica [Phys. Rev. Lett. 120, 226101 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.120.226101.

Bending Rigidity of 2D Silica.

A chemically stable bilayers of SiO_{2} (2D silica) is a new, wide band gap 2D material. Up till now graphene has been the only 2D material where the bending rigidity has been measured. Here we present inelastic helium atom scattering data from 2D silica on Ru(0001) and extract the first bending rigidity, κ, measurements for a nonmonoatomic 2D material of definable thickness. We find a value of κ=8.8 eV±0.5 eV which is of the same order of magnitude as theoretical values in the literature for freestanding crystalline 2D silica.

Atomic resolution imaging of beryl: an investigation of the nano-channel occupation.

Beryl in different varieties (emerald, aquamarine, heliodor etc.) displays a wide range of colours that have fascinated humans throughout history. Beryl is a hexagonal cyclo-silicate (ring-silicate) with channels going through the crystal along the c-axis. The channels are about 0.5 nm in diameter and can be occupied by water and alkali ions. Pure beryl (Be3 Al2 Si6 O18 ) is colourless (variety goshenite). The characteristic colours are believed to be mainly generated through substitutions with metal atoms in the lattice. Which atoms that are substituted is still debated it has been proposed that metal ions may also be enclosed in the channels and that this can also contribute to the crystal colouring. So far spectroscopy studies have not been able to fully answer this. Here we present the first experiments using atomic resolution scanning transmission electron microscope imaging (STEM) to investigate the channel occupation in beryl. We present images of a natural beryl crystal (variety heliodor) from the Bin Thuan Province in Vietnam. The channel occupation can be visualized. Based on the image contrast in combination with ex situ element analysis we suggest that some or all of the atoms that are visible in the channels are Fe ions.

Diagnostic possibilities from a serum sample-Clinical value of new methods within small animal reproduction, with focus on anti-Müllerian hormone.

During the last decade, analysis of anti-Müllerian hormone (AMH), highly conserved between mammalian species, has contributed to new information in reproductive endocrinology, due to clinically available diagnostic assays. AMH is produced solely in the gonads, in the Sertoli cells of testes and granulosa cells of the ovary, and thus offers possibilities to diagnose physiologic and pathologic conditions involving these organs. This article reviews indications for AMH analysis in cats and dogs, including diagnosing the presence of gonads, and granulosa or Sertoli cell tumours. Diagnostic challenges are addressed. One specific organ, the prostate, is commonly affected by pathologic changes in older dogs. A commercial assay for analysing canine prostatic specific esterase (CPSE) enables analysis of CPSE in clinical practice, of potential value in the workup of benign prostatic hyperplasia in male dogs. This is described in this review, as is a new method for analysis of steroids: liquid chromatography-tandem mass spectrometry LC-MS/MS. Steroids have since long been analysed in studies on reproduction, and LC-MS/MS has the advantage of allowing analysis of panels of multiple steroids from small sample volumes. Altogether, these available methods may give new insights into small animal reproduction and are valuable tools for the practicing veterinarian.

Reversible, irreversible and effective transverse relaxation rates in normal aging brain at 3T.

Quantitative transverse relaxation rates in normal aging brain are essential to investigate pathologies associated with iron accumulation and tissue degeneration. Since absolute values depend on imaging methods and magnetic field strengths, continuous evaluation of specific reference values remains requisite. Multi-echo turbo spin echo and multi-echo gradient recalled echo imaging sequences were applied to 66 healthy subjects (18-84years) at 3T to quantify the irreversible (R2), effective (R2*) and reversible (R2'=R2*-R2) transverse relaxation rates. Representative regions-of-interest (ROIs) were determined automatically in gray matter (GM) and white matter (WM) on T1-weighted scans. Phantom experiments of different sized iron-oxide particles were conducted to explore the correlation of R2' related to R2 for the evaluation of the size of iron deposits. R2 decreased with age for the majority of ROIs, but increased for putamen, head of caudate nucleus and nucleus accumbens. R2* and R2' increased with age in deep GM structures except for the thalamus. R2* and R2' showed a distinct dependency on fiber orientation in exemplary WM regions. R2', R2 and R2* were strongly linear proportional to age-related iron content in deep GM with slopes of 0.88, 0.18 and 1.08 in [1/s/mg Fe per 100g wet tissue] and intercepts of 1.69, 9.25 and 10.69 in [1/s], respectively. Linear and non-linear curve fitting of R2' vs. R2 in phantoms revealed increased slopes with increasing particle size. In vivo, averaged R2' vs. R2 data points of patients with Parkinson's disease and progressive supranuclear palsy were above the fitted curves of healthy subjects suggesting larger sized iron deposits in these neurodegenerative diseases. Decreased R2 with age may reflect physiological tissue degeneration, whereas increased R2* and R2' with age most likely denote physiological iron accumulation. The low intercept of R2' vs. iron content suggests a nearly sole sensitivity of R2' to iron in deep GM, potentially allowing a more specific estimation of the iron content than R2 or R2*. Since R2* and R2' depend on the fiber orientation, their feasibility to estimate iron content in WM is challenging. The analysis of R2' related to R2 may provide valuable information about the size of iron deposits.

Resolving ultrafast heating of dense cryogenic hydrogen.

We report on the dynamics of ultrafast heating in cryogenic hydrogen initiated by a ≲300 fs, 92 eV free electron laser x-ray burst. The rise of the x-ray scattering amplitude from a second x-ray pulse probes the transition from dense cryogenic molecular hydrogen to a nearly uncorrelated plasmalike structure, indicating an electron-ion equilibration time of ∼0.9 ps. The rise time agrees with radiation hydrodynamics simulations based on a conductivity model for partially ionized plasma that is validated by two-temperature density-functional theory.

Two dimensional imaging of the virtual source of a supersonic beam: helium at 125 K.

Here we present the first two-dimensional images of the virtual source of a supersonic helium expansion. The images were obtained using a free-standing Fresnel zone plate with an outermost zone width of 50 nm as imaging lens and a beam cooled to around 125 K. The nozzle diameter was 10 µm. The virtual source diameter was found to increase with stagnation pressure from 140 ± 30 µm at po = 21 bar up to 270 ± 25 µm at po = 101 bar. The experimental results are compared to a theoretical model based on the solution of the Boltzmann equation by the method of moments. The quantum mechanical cross sections used in the model have been calculated for the Lennard-Jones (LJ) and the Hurly-Moldover (HM) potentials. By using a scaling of the perpendicular temperature that parametrizes the perpendicular velocity distribution based on a continuum expansion approach, the LJ potential shows a good overall agreement with the experiment. However, at higher pressures the data points lie in between the two theoretical curves and the slope of the trend is more similar to the HM curve. Real gas corrections to enthalpy are considered but they affect the results less than the experimental errors.

Evolution of ac conductivity in nonequilibrium warm dense gold.

Using a chirped pulse probe technique, we have obtained single-shot measurements of temporal evolution of ac conductivity at 1.55 eV (800 nm) during electron energy relaxation in nonequilibrium warm dense gold with energy densities up to 4.1 MJ/kg (8×10(10) J/m3). The results uncover important changes that have been masked in an earlier experiment. Equally significant, they provide valuable tests of an ab initio model for the calculation of electron heat capacity, electron-ion coupling, and ac conductivity in a single, first principles framework. While measurements of the real part of ac conductivity corroborate our theoretical temperature-dependent electron heat capacity, they point to an electron-ion coupling factor of ∼2.2×10(16) W/m3 K, significantly below that predicted by theory. In addition, measurements of the imaginary part of ac conductivity reveal the need to improve theoretical treatment of intraband contributions at very low photon energy.

Ultrafast short-range disordering of femtosecond-laser-heated warm dense aluminum.

We have probed, with time-resolved x-ray absorption near-edge spectroscopy (XANES), a femtosecond-laser-heated aluminum foil with fluences up to 1 J/cm2. The spectra reveal a loss of the short-range order in a few picoseconds. This time scale is compared with the electron-ion equilibration time, calculated with a two-temperature model. Hydrodynamic simulations shed light on complex features that affect the foil dynamics, including progressive density change from solid to liquid (∼10 ps). In this density range, quantum molecular dynamics simulations indicate that XANES is a relevant probe of the ionic temperature.

Determining the fibrillar orientation of bast fibres with polarized light microscopy: the modified Herzog test (red plate test) explained.

The identification of bast fibre samples, in particular, bast fibres used in textiles, is an important issue in archaeology, criminology and other scientific fields. One of the characteristic features of bast fibres is their fibrillar orientation, referred to as Z- or S twist (or alternatively right- and left-handed fibres). An empirical test for determining the fibrillar orientation using polarized light microscopy has been known in the community for many years. It is referred to as the modified Herzog test or red plate test. The test has the reputation for never producing false results, but also for occasionally not working. However, so far, no proper justification has been provided in the literature that the 'no false results' assumption is really correct and it has also not been clear up till now, why the method sometimes does not work. In this paper, we present an analytical model for the modified Herzog test, which explains why the test never gives a false result. We also provide an explanation for why the Herzog test sometimes does not work: According to our model, the Herzog test will not work if none of the three distinct layers in the secondary cell wall is significantly thicker than the others.

Quantitative T2' imaging in patients with clinically isolated syndrome.

OBJECTIVE: The T2' imaging has been shown to be sensitive to oxygen saturation changes in normal appearing white and grey matter (NAWM, NAGM) in patients with relapsing-remitting multiple sclerosis (RRMS). We aimed to explore the presence and extent of T2' changes in patients with a clinically isolated syndrome (CIS) and a possible association of T2' with conventional magnetic resonance imaging and clinical outcomes. MATERIAL AND METHODS: Quantitative T2- and T2*-weighted images were acquired in 32 treatment-naive patients with a CIS within 3 months of presentation and 15 age-matched healthy controls (HC). Quantitative T2' values were determined in six regions of interest (ROIs). RESULTS: The T2' values in CIS did not differ significantly from those in HC. Among patients, T2' values correlated positively with the T2 lesion volume (T2LV, r = 0.34, P < 0.05). T2' values of the frontal NAWM correlated with the T2LV (r = 0.35, P < 0.05) and T2 lesion count (r = 0.4, P = 0.02). CONCLUSION: As opposed to RRMS, patients with CIS did not show T2' alterations compared to HC. However, the association between the T2LV and higher T2' values suggests that T2' reflects disease evolution. In CIS metabolic changes might be masked by compensatory mechanisms and become overt when disease progresses as has been shown for RRMS patients.

Complement takes its Toll: an inflammatory crosstalk between Toll-like receptors and the receptors for the complement anaphylatoxin C5a.

The innate immune system is responsible for a rapid inflammatory response to pathogens that is essential for the clearance of infections. Although this response is vital, it is nonetheless potentially harmful, and dysregulated inflammation is a feature of many disease states. Thus, the mechanisms that regulate the release of soluble mediators of inflammation are an active focus of investigation. The activation by infections of two key components of the innate immune system, the Toll-like receptors (TLRs) and complement, leading to the release of soluble mediators of inflammation, is critical to microbial killing and clearance. Both TLRs and complement are independently capable of triggering pro-inflammatory responses, but their synergistic interaction resulting from a substantial crosstalk markedly amplifies those responses and may contribute to the pathophysiology of diseases such as sepsis.

Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs.

Dogs enrolled in a Swedish insurance company (during 1995-2006) were studied for development of pyometra and mammary tumours (MTs), with special attention to breed and age. There were over 260,000 female dogs with over 1,000,000 dog-years at risk (DYAR) in the database, using data on bitches up to 10 years of age and 110 breeds with over 1000 DYAR. In total, 20 423 bitches were diagnosed with pyometra and 11,758 with MTs and 30,131 with either or both of the two diseases. The incidence rate (IR) for pyometra was 199 (95% CI 196-202), for MTs 112 (95% CI 110-114) and for either or both of the two diseases 297 (95% CI 294-301) dogs per 10,000 DYAR. The mean age of diagnosis pyometra was 7.0 years (SD ± 2.2), MTs 8.0 years (SD ± 1.6). In all breeds, the overall proportion of the bitches that developed disease by 10 years of age was for pyometra 19%, MTs 13%, and either or both of two diseases 30%. The top 10 breeds diagnosed with either or both of the two diseases were the Leonberger (73%), Irish Wolfhound (69%), Bernese Mountain Dog (69%), Great Dane (68%), Staffordshire Bull Terrier (66%), Rottweiler (65%), Bullterrier (62%), Doberman (62%), Bouvier des Flandres (60%), Airdaleterrier (60%). These data provide information of the combined disease incidence in a large number of different breeds. Breed variations in incidence rate suggests genetic components in disease development. Our study may be valuable in the search for genetic risk-factors or protective factors.

Canine herpesvirus during pregnancy and non-pregnant luteal phase.

Canine herpesvirus (CHV) is a widespread infection among dogs that typically get latently infected after exposure and can reactivate the infection after stress. The aim of the present study was to study the effects of latent CHV infection during pregnancy on pregnancy outcome, and to study if there are signs of genital viral reactivation during pregnancy or during non-pregnant luteal phase. Twelve mated bitches and eight control bitches were followed and sampled regularly during pregnancy or non-pregnant luteal phase. Blood samples were taken for antibody analysis and vaginal swabs for real-time PCR analysis. Three of the pregnant bitches were vaccinated against CHV during pregnancy. All bitches had antibodies to CHV. Two pregnant bitches that were not vaccinated had a twofold or larger increase in CHV titre, with no negative effects detected on pregnancy. Higher titres were not associated with smaller litters or with vaccination. There was no consistent variation in antibody titres due to pregnancy or non-pregnant luteal phase. Vaginal excretion of CHV was not detected from any of the bitches.

Tumour necrosis factor in the canine endometrium: an immunohistochemical study.

Tumour necrosis factor (TNF), a pleiotropic cytokine that regulates cell growth and differentiation as well as the synthesis of other cytokines, has been identified in the uterus of several species describing a cyclic pattern, eventually under ovarian steroid regulation. Information is yet limited on the presence of TNF protein in the canine endometrium during the oestrous cycle and early pregnancy. This study depicts the temporal immunolocalization of TNF in the bitch endometrium along the oestrous cycle and changes associated with the early steps of embryo invasion. TNF immunolabelling was found in both the stromal fibroblasts and epithelial components of the canine endometrium in all stages studied. Stromal immunostaining was more intense than that of the epithelia, in all the stages of the oestrous cycle. In addition, a tendency for a decrease in the surface epithelium intensity score was found in early dioestrus. A positive glandular content was only observed in anoestrus and proestrus stages. In early pregnancy (days 13-16), TNF immunolabelling was detected at the embryo-maternal surface, in the syncytium cords and the trophoblast, as well in the endometrial stroma and the basal endometrial glands, but not in the lacunar epithelium. The overall TNF immunoreactivity was higher in early pregnancy samples in comparison with those of the early dioestrus and dioestrus stages, suggesting it plays a role during implantation.

Serum concentration of mineralocorticoids, glucocorticoids, and sex steroids in peripartum bitches.

The aim of the work was to describe the profile of steroid hormones in the peripartum period of the bitch. Twenty-five healthy pregnant bitches presented for pregnancy monitoring and parturition assistance were included in the study. A blood sample was collected for routine progesterone assay, and serum was stored at -20°C. The day of parturition and the number of delivered puppies were registered. Concentrations of corticosteroids, androgens, progestogens, estrogens, for a total number of 17 different hormones, were measured using ultra-performance supercritical fluid chromatography-tandem mass spectrometry. Data were analyzed using a repeated measure, mixed-model approach, taking into account day (from day -4 to day +2 from parturition), age, parity (primiparous vs pluriparous), number of delivered puppies (<4 vs 4-8 vs > 8), and interactions between factors. Day related to parturition significantly affected the concentration of progesterone (P < 0.001), testosterone (P < 0.001), 17α-hydroxyprogesterone (P = 0.0002), and cortisone (P = 0.006). Estrogen concentration did not show any significant variation over time. Testosterone and androstenedione showed an abrupt decline on the day of parturition. The concentration of all glucocorticoids increased the day before parturition. Age or parity was not significantly associated with any of the steroids. Litter size significantly affected concentrations of aldosterone (P = 0.02) and etiocholanolone (P = 0.01). Aldosterone concentrations were higher in litters with 4 to 8 pups than in litters with more than 8 pups (P = 0.02). None of the steroids measured in our study, with the already known exception of progesterone, shows potential to be clinically useful in predicting the onset of parturition in the bitch.

Low-energy electron ionization mass spectrometer for efficient detection of low mass species.

The design of a high-efficiency mass spectrometer is described, aimed at residual gas detection of low mass species using low-energy electron impact, with particular applications in helium atom microscopy and atomic or molecular scattering. The instrument consists of an extended ionization volume, where electrons emitted from a hot filament are confined using a solenoidal magnetic field to give a high ionization probability. Electron space charge is used to confine and extract the gas ions formed, which are then passed through a magnetic sector mass filter before reaching an ion counter. The design and implementation of each of the major components are described in turn, followed by the overall performance of the detector in terms of mass separation, detection efficiency, time response, and background count rates. The linearity of response with emission current and magnetic field is discussed. The detection efficiency for helium is very high, reaching as much as 0.5%, with a time constant of (198 ± 6) ms and a background signal equivalent to an incoming helium flux of (8.7 ± 0.2) × 106 s-1.

Human induced pluripotent stem cells (BIONi010-C) generate tight cell monolayers with blood-brain barrier traits and functional expression of large neutral amino acid transporter 1 (SLC7A5).

The barrier properties of the brain capillary endothelium, the blood-brain barrier (BBB) restricts uptake of most small and all large molecule drug compounds to the CNS. There is a need for predictive human in vitro models of the BBB to enable studies of brain drug delivery. Here, we investigated whether human induced pluripotent stem cell (hiPSC) line (BIONi010-C) could be differentiated to brain capillary endothelial- like cells (BCEC) and evaluated their potential use in drug delivery studies. BIONi010-C hIPSCs were differentiated according to established protocols. BCEC monolayers displayed transendothelial electrical resistance (TEER) values of 5,829±354 Ω∙cm2, a Papp,mannitol of 1.09±0.15 ∙ 10-6 cm∙s-1 and a Papp,diazepam of 85.7 ± 5.9 ∙ 10-6 cm ∙s-1. The Pdiazepam/Pmannitol ratio of ~80, indicated a large dynamic passive permeability range. Monolayers maintained their integrity after medium exchange. Claudin-5, Occludin, Zonulae Occludens 1 and VE-Cadherin were expressed at the cell-cell contact zones. Efflux transporters were present at the mRNA level, but functional efflux of substrates was not detected. Transferrin-receptor (TFR), Low density lipoprotein receptor-related protein 1 (LRP1) and Basigin receptors were expressed at the mRNA-level. The presence and localization of TFR and LRP1 were verified at the protein level. A wide range of BBB-expressed solute carriers (SLC's) were detected at the mRNA level. The presence and localization of SLC transporters GLUT1 and LAT1 was verified at the protein level. Functional studies revealed transport of the LAT1 substrate [3H]-L-Leucine and the LRP1 substrate angiopep-2. In conclusion, we have demonstrated that BIONi010-C-derived BCEC monolayers exhibited, BBB properties including barrier tightness and integrity, a high dynamic range, expression of some of the BBB receptor and transporter expression, as well as functional transport of LAT1 and LRP1 substrates. This suggests that BIONi010-C-derived BCEC monolayers may be useful for studying the roles of LAT-1 and LRP1 in brain drug delivery.