The differential expression of Kiss1, MMP9 and angiogenic regulators across the feto-maternal interface of healthy human pregnancies:implications for trophoblast invasion and vessel development

Genes involved in invasion of trophoblast cells and angiogenesis are crucial in determining pregnancy outcome. We therefore studied expression profiles of these genes in both fetal and maternal tissues to enhance our understanding of feto-maternal dialogue. We investigated the expression of genes involved in trophoblast invasion, namely Kiss1, Kiss1 Receptor (Kiss1R) and MMP9 as well as the expression of angiogenic ligands Vascular Endothelial Growth Factor-A ( VEGF-A) and Prokineticin-1 ( PROK1 ) and their respective receptors (VEGFR1, VEGFR2 and PROK1R ) across the feto-maternal interface of healthy human pregnancies. The placenta, placental bed and decidua parietalis were sampled at elective caesarean delivery. Real-time RT-PCR was used to investigate transcription, while immunohistochemistry and western blot analyses were utilized to study protein expression. We found that the expression of Kiss1 (p<0.001), Kiss1R (p<0.05) and MMP9 (p<0.01) were higher in the placenta compared to the placental bed and decidua parietalis. In contrast, the expression of VEGF-A was highest in the placental bed ( p<0.001 ). While VEGFR1 expression was highest in the placenta (p<0.01), the expression of VEGFR2 was highest in the placental bed (p<0.001). Lastly, both PROK1 (p<0.001) and its receptor PROK1R (p<0.001) had highest expression in the placenta. Genes associated with trophoblast invasion were highly expressed in the placenta which could suggest that the influence on invasion capacity may largely be exercised at the fetal level. Furthermore, our findings on angiogenic gene expression profiles suggest that angiogenesis may be regulated by two distinct pathways with the PROK1/PROK1R system specifically mediating angiogenesis in the fetus and VEGFA/VEGFR2 ligand-receptor pair predominantly mediating maternal angiogenesis

Cubic boron phosphide epitaxy on zirconium diboride

Cubic boron phosphide (BP) is one of the least studied III-V compound semiconductors, in part because it is difficult to prepare in high quality form. In this study, zirconium diboride (ZrB2) was studied as a potential substrate for BP epitaxial layers, because of its advantages of a low lattice constant mismatch and high thermal stability. Two types of substrates were considered: ZrB2(0001) epitaxial films on 4H-SiC (0001) and bulk ZrB2(0001) single crystals. The optimal temperature for epitaxy on these substrates was 1100 degrees C; higher and lower temperatures resulted in polycrystalline films. The BP film/ZrB2 interface was abrupt as confirmed by cross-sectional transmission electron microscopy, attesting to the stability of ZrB2 under BP deposition conditions. The BP films were under compressive and tensile strain on ZrB2 and ZrB2/4H-SiC substrates, respectively, as determined by Raman spectroscopy, due to differences in the substrate/film coefficients of thermal expansion. This study suggests that with further optimization, ZrB2 can be an excellent substrate for BP epitaxial films. (C) 2017 Elsevier B.V. All rights reserved.Funding Agencies|Department of Energy [GEGF001846]; Swedish Research Council (VR) [621-2010-3921]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]</p

Exploiting the P L2,3 absorption edge for optics: spectroscopic and structural characterization of cubic boron phosphide thin films

The transmission of cubic boron phosphide (c-BP) thin films, prepared by chemical vapor deposition (CVD), was evaluated near the phosphorous L2,3 and boron K absorption edge. The c-BP films were analyzed with transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES), to study their structural and chemical properties. The TEM analysis reveals that c-BP initially grows in islands. The merging of the P L2,3, P K and B K absorption edges culminates in a sharp absorption feature starting at 130 eV, showing that c-BP can be used in applications that require a relatively transparent material in the energy range just below that absorption feature. Due to experimental constraints the samples were grown at a temperature significantly below the temperature for optimal crystal growth. XANES analysis showed that, as a result of the reduced crystal quality, the intensities of the absorption transitions are reduced compared to those in high quality crystalline reference samples. Optimizing the quality of the BP films will increase the contrast in transmission across the absorption edge

Epitaxy of Boron Phosphide on Aluminum Nitride(0001)/Sapphire Substrate

The boron phosphide (BP) semiconductor has many remarkable features, including high thermal neutron capture cross section of the ¹⁰B isotope, making it attractive for neutron detection applications. Effective and efficient neutron detection require BP to also have high crystal quality with optimum electrical properties. Here, we present the heteroepitaxial growth of high quality BP films on a superior aluminum nitride(0001)/sapphire substrate by chemical vapor deposition. The effect of process variables on crystalline and morphological properties of BP was examined in detail. BP deposited at high temperatures and high reactant flow rate ratios produced films with increased grain size and improved crystalline orientation. Narrower full width at half-maximum values of BP Raman peaks (6.1 cm^–1) and ω rocking curves (352 arcsec) compared to values in the literature confirm the high crystalline quality of produced films. The films were <i>n</i>-type with the highest electron mobility of 37.8 cm²/V·s and lowest carrier concentration of 3.15 × 10¹⁸ cm^–3. Rotational twinning in BP due to degenerate epitaxy caused by 3-fold BP(111) on 6-fold AlN(0001) was confirmed by synchrotron white beam X-ray topography. This preliminary study showed that AlN is an excellent substrate for growing high quality BP epitaxial films with promising potential for further enhancement of BP properties