Polaronic state and nanometer-scale phase separation in colossal magnetoresistive manganites

High resolution topographic images obtained by scanning tunneling microscope in the insulating state of Pr0.68Pb0.32MnO3 single crystals showed regular stripe-like or zigzag patterns on a width scale of 0.4 - 0.5 nm confirming a high temperature polaronic state. Spectroscopic studies revealed inhomogeneous maps of zero-bias conductance with small patches of metallic clusters on length scale of 2 - 3 nm only within a narrow temperature range close to the metal-insulator transition. The results give a direct observation of polarons in the insulating state, phase separation of nanometer-scale metallic clusters in the paramagnetic metallic state, and a homogeneous ferromagnetic state

Electronic structure of Pr2MnNiO6 from x-ray photoemission, absorption and density functional theory

The electronic structure of double perovskite Pr2MnNiO6 is studied using core x-ray photoelectron spectroscopy and x-ray absorption spectroscopy. The 2p x-ray absorption spectra show that Mn and Ni are in 2+ and 4+ states respectively. Using charge transfer multiplet analysis of Ni and Mn 2p XPS spectra, we find charge transfer energies {\Delta} of 3.5 and 2.5 eV for Ni and Mn respectively. The ground state of Ni2+ and Mn4+ reveal a higher d electron count of 8.21 and 3.38 respectively as compared to the atomic values of 8.00 and 3.00 respectively thereby indicating the covalent nature of the system. The O 1s edge absorption spectra reveal a band gap of 0.9 eV which is comparable to the value obtained from first principle calculations for U-J >= 2 eV. The density of states clearly reveal a strong p-d type charge transfer character of the system, with band gap proportional to average charge transfer energy of Ni2+ and Mn4+ ions.Comment: 18 pages, 9 figure

The ADIPS pilot national diabetes in pregnancy benchmarking programme

Background: To test the feasibility of benchmarking the care of women with pregnancies complicated by hyperglycaemia. Methods: A retrospective audit of volunteer diabetes services in Australia and New Zealand involving singleton pregnancies resulting in live births between 2014 and 2020. Ranges are shown and compared across services. Results: The audit included 10,144 pregnancies (gestational diabetes mellitus (GDM) = 8696; type 1 diabetes (T1D) = 435; type 2 diabetes (T2D) = 1013) from 11 diabetes services. Among women with GDM, diet alone was used in 39.4% (ranging among centres from 28.8-57.3%), metformin alone in 18.8% (0.4-43.7%), and metformin and insulin in 10.1% (1.5-23.4%); when compared between sites, all p 6.5% (48 mmol/mol)), 78.4% and 54.6%, respectively (p < 0.001). Conclusion: Management of maternal hyperglycaemia and pregnancy outcomes varied significantly. The maintenance and extension of this benchmarking service provides opportunities to identify policy and clinical approaches to improve pregnancy outcomes among women with hyperglycaemia in pregnancy

Manganese(II) Complexes with Schiff Bases Immobilized on Nanosilica as Catalysts of the Reaction of Ozone Decomposition

In this article, we submit the description of synthesis and identification of manganese(II) complexes with pyrogenic nanosilica-immobilized (d av = 10 nm; S sp = 290 m2/g) hydroxyaldimine ligands (Mn(L)2/Si): salicilaldiminopropyl (L1); 5-bromosalicilaldiminopropyl (L2); 2-hydroxynaphtaldiminopropyl (L3); 2-hydroxy-3-methoxybenzaldiminopropyl (L4); 2-hydroxy-3,5-dichloroacetophenoniminopropyl (L5); and 4-hydroxy-3-methoxybenzaldiminopropyl (L6). The ligands and complexes were characterized by UV-VIS and IR spectrometry. Nanocomposites consisting of complexes Mn(L)2/Si showed a high catalytic activity in low-temperature ozone decomposition in the range of concentrations between 2.1 × 10−6 and 8.4 × 10−6 mol/l. The number of catalytic cycles increased for isostructural pseudotetrahedral complexes Mn(L)2/Si (L1–L5) in the following order: Mn(L3)2 >> Mn(L4)2 > Mn(L1)2 > Mn(L2)2 > Mn(L5)2. In the case of pseudooctahedral complexes with L6, the change of coordination polyhedral does not influence the kinetics and stoichiometric parameters of the reaction

Falling Insulin Requirements and Placental Dysfunction in Women with Pre-Existing Diabetes During Pregnancy

The second half of pregnancy is characterized by a 50-70% rise in insulin resistance due to placental mediated hormone production. In women with pre-existing diabetes, this period corresponds to an increase in insulin requirements. However, less is known about the significance of a large fall in insulin requirements, when and whether this adversely impacts maternal and fetal outcomes. Falling insulin requirements (FIR) in late pregnancy has been thought to be a marker of placental insufficiency prompting admission to hospital for maternal and fetal monitoring as well as emergency delivery in some cases. However, the limited cohort studies which have looked at this group of patients failed to show any difference in maternal or fetal outcomes. Furthermore, no previous studies have directly associated FIR with evidence of placental insufficiency and it remains unclear why some women have large falls in insulin requirements and what the underlying pathophysiology is. In this thesis, through two clinical studies, the association of FIR with placental insufficiency and maternal and fetal outcomes was assessed. In addition, the pathophysiology of FIR was investigated

Falling insulin requirements are associated with adverse obstetric outcomes in women with preexisting diabetes

OBJECTIVE To investigate the clinical significance of falling insulin requirements in women with preexisting or overt diabetes in pregnancy.RESEARCH DESIGN AND METHODS A retrospective review of 139 pregnancies was conducted in women, with preexisting diabetes, delivering between January 2010 and January 2013. Women with falling insulin requirements of 15% or more from the peak total daily dose in late pregnancy were considered case subjects (n = 35). The primary outcome consisted of a composite of clinical markers of placental dysfunction, including preeclampsia, small for gestational age (SGA, ≤5th percentile for gestational age), stillbirth (>20 weeks), and premature delivery (≤30 weeks).RESULTS A total of 25.2%of women had >15%fall in insulin requirements with nulliparity as the only predictor at baseline (odds ratio [OR] 2.5 [95% CI 1.1-5.7], P = 0.03). Falling insulin requirements were associated with an increased risk of preeclampsia (OR 3.5 [1.1-10.7], P < 0.05) and the composite of clinical markers of placental dysfunction (4.4 [1.73-11.26], P = 0.002). Although falling insulin requirements were associated with higher rates of SGA (3.4 [1.0-11.3], P = 0.048), they were not associated with other adverse neonatal outcomes. However, there was a higher incidence of neonatal intensive care unit admission (15.5 [3.1-77.6], P = 0.001) and earlier delivery in this group (median 37.7 weeks [IQR 34.3-38.4] vs. 38.3 weeks [37.4-38.9], P = 0.014).CONCLUSIONS Falling insulin requirements, in women with preexisting diabetes, are associated with an increased risk of complications related to placental dysfunction. Further prospective studies are needed to guide clinical management

Effect of pregnancy on insulin requirements differs between type 1 and type 2 diabetes : a cohort study of 222 pregnancies

Background: Knowledge about the expected insulin requirements during pregnancy, in women with pre-existing diabetes may assist clinicians to effectively respond to gestation-specific changes in glycemic pattern. Few studies have examined differences between type 1 (T1DM) and type 2 diabetes (T2DM). Aims: To compare patterns of insulin requirements in pregnancy for women with pre-existing T1DM and T2DM. Material and Methods: A retrospective cohort study of 222 pregnancies was conducted in women with pre-existing diabetes, (67 with T1DM, 155 with T2DM). Total daily insulin dose (TID) at the end of each trimester, recorded as units and units per kilogram (median, 25th–75th percentile) as well as percentage increase in insulin dose per trimester were compared. Results: Women with T1DM had higher insulin requirements in the first 2 trimesters than those with T2DM (0.69(0.58– 0.85) vs 0.36(0.0–0.7) units/kg in first trimester; 0.80(0.62–0.95) vs 0.61(0.27–0.95) units/kg, P < 0.005) in second trimester), but requirements in late pregnancy were similar (0.97(0.69–1.29) vs 0.95(0.53–1.32) units/kg, P = 0.54). Women with T2DM needed much greater increases in insulin per trimester compared to T1DM (P < 0.001). Women with T1DM had a net fall in insulin requirements (3.7% in the first trimester and 4.1% in the late third trimester) while those with T2DM did not. Conclusions: This is the largest comparison study of insulin requirements in women with pre-existing diabetes, highlighting important trimester specific differences between T1DM and T2DM to guide insulin titration during pregnancy. Our findings suggest a differential effect of pregnancy-mediated insulin resistance by type of diabetes

Magnetic, electron magnetic resonance and optical studies of Pr0.7Pb0.3MnO3Pr_{0.7}Pb_{0.3}MnO_3 nanoparticles

In this paper we present the preparation and physical property studies on $Pr_{0.7}Pb_{0.3}MnO_3$(PPMO) nanoparticles with an average grain size of 5 nm. We find from SQUID magnetometry measurements that the Curie temperature $(T_C)$ remains unaltered at 205K with decrease in the particle size down to 5 nm in comparison with bulk $T_C$ (200 K). From electron magnetic resonance (EMR) measurements, it is found that PPMO nanoparticles are more homogeneous than bulk PPMO. Only one EMR signal is observed down to 4K in PPMO with an average particle size of 5 nm in contrast to the two EMR signal behaviour observed in bulk PPMO (200–240 K). The origin of the two EMR signals in the bulk was attributed to possible phase separation Padmanabhan B etal 2007 Physica B 398 107). Such a phase separation is therefore concluded to be absent in nano-PPMO. In addition, temperature-dependent optical phonon measurements performed on 5 nm PPMO nanoparticles indicate the insulator–metal transition $(T_{MI} = 230 K)$, which is nearly the same as that of the bulk sample $(T_{MI} = 235 K)$