Translocation of positively and negatively charged polystyrene nanoparticles in an in vitro placental model

AbstractTo obtain insight in translocation of nanoparticles across the placental barrier, translocation was studied for one positively and two negatively charged polystyrene nanoparticles (PS-NPs) of similar size in an in vitro model. The model consisted of BeWo b30 cells, derived from a human choriocarcinoma grown on a transwell insert forming a cell layer that separates an apical from a basolateral compartment. PS-NPs were characterized with respect to size, surface charge, morphology and protein corona. Translocation of PS-NPs was not related to PS-NP charge. Two PS-NPs were translocated across the BeWo transwell model to a lower extent than amoxicillin, a model compound known to be translocated over the placental barrier to only a limited extent, whereas one PS-NP showed a slightly higher translocation. Studies on the effect of transporter inhibitors on the translocation of the PS-NPs indicated that their translocation was not mediated by known transporters and mainly dependent on passive diffusion. It is concluded that the BeWo b30 model can be used as an efficient method to get an initial qualitative impression about the capacity of NPs to translocate across the placental barrier and set priorities in further in vivo studies on translocation of NPs to the fetus

Te covered Si(001): a variable surface reconstruction

At a given temperature, clean and adatom covered silicon surfaces usually exhibit well-defined reconstruction patterns. Our finite temperature ab-initio molecular dynamics calculations show that the tellurium covered Si(001) surface is an exception. Soft longitudinal modes of surface phonons due to the strongly anharmonic potential of the bridged tellurium atoms prevent the reconstruction structure from attaining any permanent, two dimensional periodic geometry. This explains why experiments attempting to find a definite model for the reconstruction have reached conflicting conclusions.Comment: 4 pages, 3 gif figure

Charge dynamics and "ferromagnetism" of A1-xLaxB6 (A=Ca and Sr)

Ferromagnetism has been reported recently in La-doped alkaline-earth hexaborides, A1-xLaxB6 (A=Ca, Sr, and Ba). We have performed the reflectivity, Hall resistivity, and magnetization measurements of A1-xLaxB6. The results indicate that A1-xLaxB6 can be regarded as a simple doped semimetal, with no signature of an excitonic state as suggested by several theories. It is also found that the surface of as-grown samples (10 micrometer in thickness) has a different electronic structure from a bulk one, and a fairly large number of paramagnetic moments are confined in this region. After eliminating these paramagnetic moments at the surface, we could not find any evidence of an intrinsic ferromagnetic moment in our samples, implying the possibility that the ferromagnetism of A1-xLaxB6 reported so far is neither intrinsic.Comment: 7 pages, 8 figure

Fermi Surface Measurements on the Low Carrier Density Ferromagnet Ca1-xLaxB6 and SrB6

Recently it has been discovered that weak ferromagnetism of a dilute 3D electron gas develops on the energy scale of the Fermi temperature in some of the hexaborides; that is, the Curie temperature approximately equals the Fermi temperature. We report the results of de Haas-van Alphen experiments on two concentrations of La-doped CaB6 as well as Ca-deficient Ca1-dB6 and Sr-deficient Sr1-dB6. The results show that a Fermi surface exists in each case and that there are significant electron-electron interactions in the low density electron gas.Comment: 4 pages, 5 figures, submitted to PR

Factoren van invloed op voedselveiligheid

In dit rapport van Agrotechnology & Food Innovations, Rikilt en het LEI wordt ingegaan op de factoren die van invloed zijn op de veiligheid van voedingsmiddelen. Deze factoren zijn onderverdeeld in twee hoofdgroepen, namelijk productaspecten en bedrijfsaspecten. Bij deze laatste zijn ook opgenomen de relevante aspecten uit de omgeving van het bedrijf, zoals de relaties met leveranciers en afnemers. Met behulp van deze aspecten zijn de hoofdgroepen van de CBL-indeling van levensmiddelen op kwalitatieve wijze ingedeeld naar de mate van risico voor voedselveiligheid. This report by Agrotechnology & Food Innovations, Rikilt and LEI looks at the factors that influence the safety of foodstuffs. These factors are subdivided into two main groups: product aspects and farm aspects. The latter also includes the relevant aspects from the farm's environment, such as the relationships with suppliers and buyers. With the aid of these aspects, the main groups of the CBL classification of foodstuffs are divided on the basis of quality according to the risk in terms of food safety

Theory of High \tc Ferromagnetism in SrB6SrB_6 family: A case of Doped Spin-1 Mott insulator in a Valence Bond Solid Phase

Doped divalent hexaborides such as $Sr_{1-x}La_xB_6$ exhibit high \tc ferromagnetism. We isolate a degenerate pair of $2p$-orbitals of boron with two valence electrons, invoke electron correlation and Hund coupling, to suggest that the undoped state is better viewed as a spin-1 Mott insulator; it is predicted to be a type of 3d Haldane gap phase with a spin gap $\sim 0.1 eV$, much smaller than the charge gap of $> 1.0 eV$ seen in ARPES. The experimentally seen high \tc `ferromagnetism' is argued to be a complex magnetic order in disguise - either a canted 6-sublattice AFM ($\approx 120^0$) order or its quantum melted version, a chiral spin liquid state, arising from a type of double exchange mechanism.Comment: 4 pages, 2 figures; minor corrections, references adde

Sex Differences in Outcome of Trauma Patients Presented with Severe Traumatic Brain Injury:A Multicenter Cohort Study

The objective of this study was to determine whether there is an association between sex and outcome in trauma patients presented with severe traumatic brain injury (TBI). A retrospective multicenter study was performed in trauma patients aged ≥ 16 years who presented with severe TBI (Head Abbreviated Injury Scale (AIS) ≥ 4) over a 4-year-period. Subgroup analyses were performed for ages 16–44 and ≥45 years. Also, patients with isolated severe TBI (other AIS ≤ 2) were assessed, likewise, with subgroup analysis for age. Sex differences in mortality, Glasgow Outcome Score (GOS), ICU admission/length of stay (LOS), hospital LOS, and mechanical ventilation (MV) were examined. A total of 1566 severe TBI patients were included (831 patients with isolated TBI). Crude analysis shows an association between female sex and lower ICU admission rates, shorter ICU/hospital LOS, and less frequent and shorter MV in severe TBI patients ≥ 45 years. After adjusting, female sex appears to be associated with shorter ICU/hospital LOS. Sex differences in mortality and GOS were not found. In conclusion, this study found sex differences in patient outcomes following severe TBI, potentially favoring (older) females, which appear to indicate shorter ICU/hospital LOS (adjusted analysis). Large prospective studies are warranted to help unravel sex differences in outcomes after severe TBI.</p

Electronic Structure of Calcium Hexaboride within the Weighted Density Approximation

We report calculations of the electronic structure of CaB$_6$ using the weighted density approximation (WDA) to density functional theory. We find a semiconducting band structure with a sizable gap, in contrast to local density approximation (LDA) results, but in accord with recent experimental data. In particular, we find an $X$-point band gap of 0.8 eV. The WDA correction of the LDA error in describing the electronic structure of CaB$_6$ is discussed in terms of the orbital character of the bands and the better cancelation of self-interactions within the WDA.Comment: 1 figur

Can CT-based gap and step-off displacement predict outcome after nonoperative treatment of acetabular fractures?

Aims: The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods:A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results: Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, &gt; 2 to 4 mm, or &gt; 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, &gt; 2 to 4 mm, or &gt; 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement &gt; 2 mm (&gt; 2 to 4 mm hazard ratio (HR) 4.9, &gt; 4 mm HR 5.6) and age &gt; 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion: Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age &gt; 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process.</p