43 research outputs found
Domain variance and superstructure across the antiferroelectric/ferroelectric phase boundary in Pb1â1.5xLax(Zr0.9TiM0.1)O3
Transmission electron microscopy, x-ray diffraction, relative permittivity as a
function of temperature, and polarization versus field loops were used to study the
antiferroelectric/ferroelectric (AFE/FE) phase boundary in Pb1â1.5xLaxZr0.9Ti0.1O3
(PLZT, 100x/90/10) ceramics. X-ray diffraction and electrical measurements indicated
a FE rhombohedral (R) to AFE tetragonal (T) phase transition between PLZT 2/90/10
and 4/90/10. Both phases exhibited superstructure reflections in electron-diffraction
patterns at 1â2{hkl} positions consistent with rotations of the octahedra in antiphase.
Previously, neutron diffraction suggested that the FER has an aâaâaâ tilt system
(Glazer notation), in agreement with its macroscopic symmetry. By analogy, it is
proposed that the AFET phase has an a0a0câ tilt system. The AFE phase was also
characterized by incommensurate superstructure along pseudocubic â©110âȘp directions,
whereas the FE phase had extra commensurate superlattice reflections at 1â2{hk0}p
positions. 1â2{hk0}p reflections are forbidden in both tilt systems, but their presence is
explained by Pb ion displacements averaged along â©111âȘ but with short coherence
antiparallel components along â©110âȘ directions. The antiparallel Pb displacements are
coupled to an aâbâbâ (a â b) monoclinic tilt system in the vicinity of the AFE/FE
boundary
Treatment-limiting renal tubulopathy in patients treated with tenofovir disoproxil fumarate.
OBJECTIVES: Tenofovir disoproxil fumarate (TDF) is widely used in the treatment or prevention of HIV and hepatitis B infection. TDF may cause renal tubulopathy in a small proportion of recipients. We aimed to study the risk factors for developing severe renal tubulopathy. METHODS: We conducted an observational cohort study with retrospective identification of cases of treatment-limiting tubulopathy during TDF exposure. We used multivariate Poisson regression analysis to identify risk factors for tubulopathy, and mixed effects models to analyse adjusted estimated glomerular filtration rate (eGFR) slopes. RESULTS: Between October 2002 and June 2013, 60 (0.4%) of 15,983 patients who had received TDF developed tubulopathy after a median exposure of 44.1 (IQR 20.4, 64.4) months. Tubulopathy cases were predominantly male (92%), of white ethnicity (93%), and exposed to antiretroviral regimens that contained boosted protease inhibitors (PI, 90%). In multivariate analysis, age, ethnicity, CD4 cell count and use of didanosine or PI were significantly associated with tubulopathy. Tubulopathy cases experienced significantly greater eGFR decline while receiving TDF than the comparator group (-6.60 [-7.70, -5.50] vs. -0.34 [-0.43, -0.26] mL/min/1.73 m2/year, p < 0.0001). CONCLUSIONS: Older age, white ethnicity, immunodeficiency and co-administration of ddI and PI were risk factors for tubulopathy in patients who received TDF-containing antiretroviral therapy. The presence of rapid eGFR decline identified TDF recipients at increased risk of tubulopathy
Nucleon electromagnetic form factors in a quark-gluon core model
We study the nucleon electromagnetic form factors in a quark-gluon core model
framework, which can be viewed as an extension of the Isgur-Karl model of
baryons. Using this picture we derive nucleon electromagnetic dipole form
factors at low Q^2 and the deviation from the dipole form at high Q^2, that are
consistent with the existing experimental data.Comment: 5 pages, 3 figure
Genome-wide association study of kidney function decline in individuals of European descent.
Genome-wide association studies (GWASs) have identified multiple loci associated with cross-sectional eGFR, but a systematic genetic analysis of kidney function decline over time is missing. Here we conducted a GWAS meta-analysis among 63,558 participants of European descent, initially from 16 cohorts with serial kidney function measurements within the CKDGen Consortium, followed by independent replication among additional participants from 13 cohorts. In stage 1 GWAS meta-analysis, single-nucleotide polymorphisms (SNPs) at MEOX2, GALNT11, IL1RAP, NPPA, HPCAL1, and CDH23 showed the strongest associations for at least one trait, in addition to the known UMOD locus, which showed genome-wide significance with an annual change in eGFR. In stage 2 meta-analysis, the significant association at UMOD was replicated. Associations at GALNT11 with Rapid Decline (annual eGFR decline of 3âml/min per 1.73âm(2) or more), and CDH23 with eGFR change among those with CKD showed significant suggestive evidence of replication. Combined stage 1 and 2 meta-analyses showed significance for UMOD, GALNT11, and CDH23. Morpholino knockdowns of galnt11 and cdh23 in zebrafish embryos each had signs of severe edema 72âh after gentamicin treatment compared with controls, but no gross morphological renal abnormalities before gentamicin administration. Thus, our results suggest a role in the deterioration of kidney function for the loci GALNT11 and CDH23, and show that the UMOD locus is significantly associated with kidney function decline.Kidney International advance online publication, 10 December 2014; doi:10.1038/ki.2014.361