The Chemistry of Spinel Ferrite Nanoparticle Nucleation, Crystallization, and Growth

The nucleation, crystallization, and growth mechanisms of MnFe2O4, CoFe2O4, NiFe2O4, and ZnFe2O4 nanocrystallites prepared from coprecipitated transition metal (TM) hydroxide precursors treated at sub-, near-, and supercritical hydrothermal conditions have been studied by in situ X-ray total scattering (TS) with pair distribution function (PDF) analysis, and in situ synchrotron powder X-ray diffraction (PXRD) with Rietveld analysis. The in situ TS experiments were carried out on 0.6 M TM hydroxide precursors prepared from aqueous metal chloride solutions using 24.5% NH4OH as the precipitating base. The PDF analysis reveals equivalent nucleation processes for the four spinel ferrite compounds under the studied hydrothermal conditions, where the TMs form edge-sharing octahedrally coordinated hydroxide units (monomers/dimers and in some cases trimers) in the aqueous precursor, which upon hydrothermal treatment nucleate through linking by tetrahedrally coordinated TMs. The in situ PXRD experiments were carried out on 1.2 M TM hydroxide precursors prepared from aqueous metal nitrate solutions using 16 M NaOH as the precipitating base. The crystallization and growth of the nanocrystallites were found to progress via different processes depending on the specific TMs and synthesis temperatures. The PXRD data show that MnFe2O4 and CoFe2O4 nanocrystallites rapidly grow (typically <1 min) to equilibrium sizes of 20-25 nm and 10-12 nm, respectively, regardless of applied temperature in the 170-420 °C range, indicating limited possibility of targeted size control. However, varying the reaction time (0-30 min) and temperature (150-400 °C) allows different sizes to be obtained for NiFe2O4 (3-30 nm) and ZnFe2O4 (3-12 nm) nanocrystallites. The mechanisms controlling the crystallization and growth (nucleation, growth by diffusion, Ostwald ripening, etc.) were examined by qualitative analysis of the evolution in refined scale factor (proportional to extent of crystallization) and mean crystallite volume (proportional to extent of growth). Interestingly, lower kinetic barriers are observed for the formation of the mixed spinels (MnFe2O4 and CoFe2O4) compared to the inverse (NiFe2O4) and normal (ZnFe2O4) spinel structured compounds, suggesting that the energy barrier for formation may be lowered when the TMs have no site preference.

High-performance hexaferrite magnets tailored through alignment of shape-controlled nanocomposites

Nanoparticles of strontium hexaferrite, SrFe12O19, were prepared by two different synthesis methods: hydrothermal (autoclave) and sol-gel autocombustion (solid-salt-matrix). The two synthesis pathways yield nanoparticles with different morphologies and correspondingly different magnetic characteristics. The autoclave synthesis results in large plate-like crystallites, which spontaneously align with a preferred crystallographic orientation when applying a uniaxial pressure, but exhibit a relatively poor coercivity. Meanwhile, the solid-salt-matrix synthesis method results in smaller less anisotropic crystallites with enhanced coercivity, but with a relatively limited ability to align under a uniaxial applied pressure. The obtained nanocrystalline powders were dry or wet mixed in different ratios followed by Spark Plasma Sintering (SPS) into dense pellets. A clear correlation between mixing ratio, the level of alignment and resulting coercivity was observed for the dry mixed samples, i.e. as more solid-salt-matrix powder is added, the texture of the pellets decreases and the coercivity increases. The best performing pellet in terms of maximum energy product (BHmax = 32.1(6) kJ m-3) was obtained by dry-mixing of 75 wt% autoclave prepared powder and 25 wt% solid-salt-matrix powder. The results presented here illustrate the potential of mixing magnetic nanoparticle powders with different shape characteristics to gain improved magnetic performance.

Exploring nurses' experiences of performing basic life support in hospital wards: An inductive thematic analysis

AIM

The aim of this study was to undertake an in-depth exploration of the lived experiences of in-hospital, non-intensive care, ward-based nurses' experiences of real-life CPR events.

BACKGROUND

There is growing evidence suggesting that may nurses not be able to successfully perform in a cardiac arrest situation. Reasons include a lack of clear leadership at the arrest, performance anxiety, role confusion and knowledge and skill degradation over time.

METHODS

In-depth semi-structured interviews were conducted with fifteen ward-based hospital nurses from three hospitals. Interviews were recorded, transcribed verbatim and inductive thematic analysis was completed using NVivo 12 software.

FINDINGS

Four main themes emerged from data. The main themes are: (1) Not Being able to Perform When it Matters, (2) Working Really Well as a Team, (3) Reflecting on the Experience: The Good, the Bad & the Ugly and (4) Learning to get it Right for Next Time CONCLUSION: Performing BLS is a stressful and anxiety-provoking experience for ward-based nurses. Anxiety levels appear to decrease slightly only when nurses have had at least one previous real-life experience with resuscitation. Current BLS education does not prepare nurses for the complexities of resuscitation. Future BLS education should focus on in-depth scenarios, including interdisciplinary team training and with greater frequency than the current yearly mandatory sessions. Listening to the lived experiences of nurses who have performed BLS has given much needed insight into approaches that educators can use to improve BLS education delivery.

Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Defect-Engineering by Solvent Mediated Mild Oxidation as a Tool to Induce Exchange Bias in Metal Doped Ferrites

The crystal site occupancy of different divalent ions and the induction of lattice defects represent an additional tool for modifying the intrinsic magnetic properties of spinel ferrites nanoparticles. Here, the relevance of the lattice defects is demonstrated in the appearance of exchange-bias and in the improvement of the magnetic properties of doped ferrites of 20 nm, obtained from the mild oxidation of core@shell (wüstite@ferrite) nanoparticles. Three types of nanoparticles (Fe0.95 O@Fe3 O4 , Co0.3 Fe0.7 O@Co0.8 Fe2.2 O4 and Ni0.17 Co0.21 Fe0.62 O@Ni0.4 Co0.3 Fe2.3 O4 ) are oxidized. As a result, the core@shell morphology is removed and transformed in a spinel-like nanoparticle, through a topotactic transformation. This study shows that most of the induced defects in these nanoparticles and their magnetic properties are driven by the inability of the Co(II) ions at the octahedral sites to migrate to tetrahedral sites, at the chosen mild oxidation temperature. In addition, the appearance of crystal defects and antiphase boundaries improves the magnetic properties of the starting compounds and leads to the appearance of exchange bias at room temperature. These results highlight the validity of the proposed method to impose novel magnetic characteristics in the technologically relevant class of nanomaterials such as spinel ferrites, expanding their potential exploitation in several application fields.

Controlling the magnetic structure in W-type hexaferrites

W-type hexaferrites with varied Co/Zn ratios were synthesized and the magnetic order was investigated using neutron powder diffraction. In SrCo₂Fe₁₆O₂₇ and SrCoZnFe₁₆O₂₇ a planar (Cm'cm') magnetic ordering was found, rather than the uniaxial ordering (P6₃/mm'c') found in SrZn₂Fe₁₆O₂₇ which is common in most W-type hexaferrites. In all three studied samples, non-collinear terms were present in the magnetic ordering. One of the non-collinear terms is common to the planar ordering in SrCoZnFe₁₆O₂₇ and uniaxial ordering in SrZn₂Fe₁₆O₂₇, which could be a sign of an imminent transition in the magnetic structure. The thermomagnetic measurements revealed magnetic transitions at 520 and 360 K for SrCo₂Fe₁₆O₂₇ and SrCoZnFe₁₆O₂₇, and Curie temperatures of 780 and 680 K, respectively, while SrZn₂Fe₁₆O₂₇ showed no transition but a Curie temperature at 590 K. This leads to the conclusion that the magnetic transition can be adjusted by fine-tuning the Co/Zn stoichiometry in the sample.

Texture formation in W-type hexaferrite by cold compaction of non-magnetic interacting anisotropic shaped precursor crystallites

Crystallites of the W-type hexaferrites, Sr(Ni_1-xZn_x)₂Fe₁₆O₂₇ (x = 0, 0.5, 1) have been aligned without applying magnetic field nor hot compaction, but through a simple synthesis process taking advantage of easy alignment of non-magnetic interacting, anisotropic-shaped precursor crystallites of goethite. The goethite precursor was prepared through a simple hydrothermal synthesis route, forming lathlike crystallites with apparent dimensions of 23.3 × 40.1 × 11.0 nm³ as extracted from powder X-ray diffraction along the a-, b- and c-axis, respectively. The calcined pellets consisted of almost phase pure W-type hexaferrites with relative small impurities of spinel ferrite (≤9.02(3) wt%). The high synthesis temperature resulted in large crystallites, which in turn caused low coercivities (H_c ≤ 5.4(1) kA m^-1) and a squareness ration (M_r/M_s, remanence (M_r) over saturation magnetisation (M_s)) close to zero for all samples. The vanishing coercivity makes M_r/M_s an unsatisfying measure of preferred orientation. Quantitative texture analysis of the samples was carried out based on 2D transmission synchrotron diffraction data collected at different orientations of the samples. The texture investigations revealed alignment of the crystallites with the c-axis normal to the pressing surface of the pellets. The SrNi₂Fe₁₆O₂₇ sample showed the highest texture index of 7.5 m.r.d.².

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

Combined neutron and X-ray powder diffraction investigations of CoFe₂O₄ are reported, aimed at investigating the robustness, reproducibility and reliability of structural parameters from Rietveld refinement.

Powder X-ray diffraction (PXRD) and neutron powder diffraction (NPD) have been used to investigate the crystal structure of CoFe₂O₄ nanoparticles prepared via different hydro­thermal synthesis routes, with particular attention given to accurately determining the spinel inversion degrees. The study is divided into four parts. In the first part, the investigations focus on the influence of using different diffraction pattern combinations (NPD, Cu-source PXRD and Co-source PXRD) for the structural modelling. It is found that combining PXRD data from a Co source with NPD data offers a robust structural model. The second part of the study evaluates the reproducibility of the employed multipattern Rietveld refinement procedure using different data sets collected on the same sample, as well as on equivalently prepared samples. The refinement procedure gives reproducible results and reveals that the synthesis method is likewise reproducible since only minor differences are noted between the samples. The third part focuses on the structural consequences of (i) the employed heating rate (achieved using three different hydro­thermal reactor types) and (ii) changing the cobalt salt in the precursors [aqueous salt solutions of Co(CH₃COOH)₂, Co(NO₃)₂ and CoCl₂] in the synthesis. It is found that increasing the heating rate causes a change in the crystal structure (unit cell and crystallite sizes) while the Co/Fe occupancy and magnetic parameters remain similar in all cases. Also, changing the type of cobalt salt does not alter the final crystal/magnetic structure of the CoFe₂O₄ nanoparticles. The last part of this study is a consideration of the chemicals and parameters used in the synthesis of the different samples. All the presented samples exhibit a similar crystal and magnetic structure, with only minor deviations. It is also evident that the refinement method used played a key role in the description of the sample.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

CHALLENGE and Face Your Fears: Virtual Reality Treatment for Auditory Hallucinations and Paranoid Ideations

Background: Many patients suffering from schizophrenia spectrum disorders continue having distressing auditory hallucinations and paranoid ideations despite receiving current treatment. Virtual reality assisted treatment offers the potential of advancing current psychotherapies for psychotic symptoms by creating virtual environments that can elicit responses (e.g. thoughts, feelings, behaviours) mirroring real-world settings. In two large-scale randomised clinical trials, we are investigating whether targeted virtual reality assisted psychotherapy can reduce psychotic symptoms and increase daily life functioning and quality of life. The CHALLENGE trial examines whether nine sessions of virtual reality-assisted psychotherapy is superior to nine sessions of standard treatments in reducing the severity, frequency, and distress of auditory hallucinations in patients with psychosis. In the Face your Fears trial we are investigating whether virtual reality assisted cognitive behavioral therapy (CBT) is superior to standard CBT in reducing levels of paranoid ideation in patients with psychosis spectrum disorders. Methods: The CHALLENGE and Face your Fears trials are randomised, assessor-blinded parallel-groups superiority clinical trials, allocating a total of 266 and 256 patients, respectively to either the experimental intervention or a control condition. The trials are currently enrolling patients; thus, no quantitative data is available yet. The main objective of this presentation is to give a qualitative account of this new psychotherapeutic methods as it is applied in both trials. Results: Qualitative data comprising case descriptions and video material will be presented at the conference. Discussion: The preliminary findings indicate great potential for these innovative treatments albeit important concerns regarding implementation will be raised.

How to execute research projects in clinical practice in a large medium secure forensic psychiatric facility

Introduction

While effective project planning is crucial for the success of a clinical research project, being able to execute the plan is even more important. In Denmark, approval for health research projects is applied for at regional or national committees on health research ethics, which have been reluctant to approve clinical research projects involving forensic psychiatric in-patients, due to the admission usually being pursuant to treatment sanctions. However, recently we received approval for a clinical research project exclusively targeted towards inpatients at a large medium secure forensic psychiatric facility in Denmark.

Objectives

Describing the process of project execution from planning to submitting the manuscript which is inherently multi-faceted and inundated with stress factors. How to connect theory, knowledge, project with clinical practice, with clinical research?

Methods

Qualitative data collecting while undertaking an exploratory, open-label, non-randomised weight reducing trial with a glucagon-like peptide-1 receptor agonist.

Results

Challenges in finding, screening, motivating, recruiting, obtaining valid confirmed consent from potential study participants and other stakeholders, team communication, responsibilities and accountabilities within the team, Pareto Principle, scope creep, building project reports manually, real-time data gathering, unpredictable and other project deliverables will be presented

Conclusions

Experiences of the hospital staff (psychiatrists, doctors and nurses) in execution process of the project investigation performed and made possible through participation of their forensic psychiatric in-patients.

Disclosure

No significant relationships.

Alignment of strontium hexaferrite, by cold compaction of anisotropic non-magnetically interacting crystallites

Cold compacted, anisotropic shaped non-magnetically interacting precursors are used to achieve aligned strontium hexaferrites. The simple process of dry mixing platy hematite and/or rod-like goethite with strontium carbonate removes the need for external magnetic fields or high temperatures during compaction to assist in alignment. The calcined strontium hexaferrite pellets all displayed preferred orientation and high levels of phase purity (>99 wt%). The mix of goethite and strontium carbonate achieved the highest degree of magnetic alignment with M_r/M_s reaching 0.83(1) obtained by vibrating sample magnetometry. The magnetic data were supported by examining crystallographic alignment using powder X-ray diffraction as well as 2D texture synchrotron analysis.

Comparison across 12 countries on knowledge, attitude, and behavior scores about medication errors in Intensive Care Units: an international study

OBJECTIVE

The aim of the study was to explore the degree of agreement of intensive care unit nurses working on a set of medication error preventive strategies and to examine possible predictors of nurses' knowledge, attitude and behavior.

MATERIALS AND METHODS

Observational, international, and cross-sectional study. Iran, Malta, Spain, Pakistan, Nepal, Qatar, Ecuador, Australia, Finland, Italy, Egypt, and Jordan were the countries included in this survey. To collect data, the Knowledge, Attitude and Behavior in Medication Errors questionnaire was used. A descriptive statistical analysis was performed for the socio-demographic characteristics of the sample and three multiple logistic regressions were performed.

RESULTS

The international sample consists of 1383 nurses, of whom 478 (34.6%) were men and 900 (65.1%) were women and their mean age was 35.61 years with a range of 19-61. Descriptive statistics conducted on the international sample show a medium to high degree of agreement among participants concerning some preventive strategies of medication error. In addition, the results of the present study show a strong relationship between positive nurses' attitudes and correct behaviors and/or adequate knowledge, as well as between adequate knowledge and correct behaviors (p< 0.01).

CONCLUSIONS

Further studies are needed to explore the issue of medication error concerning nurses' cultural backgrounds, as well as to assess similarities and disparities among international nurses.

Mechanisms behind protein-protein interactions in a β-lg-legumin co-precipitate

Interactions between pea protein and whey protein isolates in co-precipitates and blends consist of a combination of disulphide bonds, hydrophobic and electrostatic interactions. The present study aims to clarify if the two proteins with free thiols, β-lactoglobulin (β-lg) and legumin, played a significant role for these interactions. This study used different reagents to modify the conditions of interactions: N-ethylmaleimide (NEM) was used to block reactive thiols, while NaCl and SDS were used to prevent electrostatic or hydrophobic interactions, respectively. The effects of treatments were studied on protein solubility, structure and stability. SDS had no effect, while NEM and NaCl both had great effect, especially in combination. The results showed that interactions of β-lg and legumin in both co-precipitates and blends are a synergism of electrostatic interactions and disulphide bonds. Thus, β-lg and legumin are the main proteins responsible for previously observed interactions in protein isolates of whey and pea.

Reduction of serum-induced endothelial STAT3(Y705) activation is associated with preeclampsia

OBJECTIVES

Preeclampsia is associated with maternal morbidity and mortality during pregnancy, and also an increased cardiovascular disease (CVD) risk later in life. During preeclampsia, alterations in secreted placental factors leading to systemic maternal endothelial dysfunction are evident. However, little is known about the associated endothelial intracellular signaling. STAT3 is a latent cytoplasmic transcription factor involved in endothelial cell differentiation, survival, and angiogenesis. We aimed to test if preeclampsia and preeclampsia-related placental factors could alter serum-induced STAT3(Y705) activation in endothelial cells. Furthermore, if altered serum-induced endothelial STAT3 (Y705) activation is related to post-preeclamptic CVD risk.

STUDY DESIGN

HUVECs were used as a model of maternal endothelium. Experiments entailed addition of 20% human pregnancy serum as well as addition of recombinant PlGF, sFLT1 and VEGF-A_165a to the cells.

MAIN OUTCOME MEASURES

Levels of pSTAT3(Y705) related to STAT3 levels were evaluated by immunoblotting analysis.

RESULTS

Our results show that preeclamptic serum induces significantly lower STAT3(Y705) phosphorylation compared with uncomplicated pregnancy serum (P = 0.0089) in endothelial cells. Furthermore, STAT3(Y705) phosphorylation was not changed upon addition of PlGF, sFLT1, or VEGF-A_165a together with pregnancy sera compared with sera alone. Finally, sera from women with previous preeclampsia and current hypertension and carotid atherosclerotic plaques show significantly lower STAT3(Y705) phosphorylation capabilities compared with healthy women with previous uncomplicated pregnancies 8-18 years after deliveries (P = 0.029).

CONCLUSIONS

Reduction in serum-induced endothelial STAT3(Y705) activation may play an important role in the preeclampsia-associated endothelial dysfunction. Additionally, reduced endothelial STAT3(Y705) phosphorylation may contribute to increased post-preeclamptic CVD risk 8-18 years after delivery.

Effectiveness of vortioxetine in real-world clinical practice: Interim results from the relieve study

Introduction

Vortioxetine has demonstrated sustained efficacy and favorable safety profile in multiple clinical trials.

Objectives

This study aims to describe the effectiveness and safety of vortioxetine in real-world clinical practice.

Methods

RELIEVE is a prospective, multi-national, observational cohort study of outpatients initiating vortioxetine treatment for MDD at physician’s discretion and followed for 6 months. Data were collected at routine clinical visits. The primary outcome was functioning measured by Sheehan Disability Scale (SDS). Depressive symptoms measured by Patient Health Questionnaire 9-item (PHQ-9), cognitive symptoms measured by PDQ-5 and DSST were key secondary outcomes. Safety outcomes including adverse events were reported. This interim analysis presents results of 527 patients who completed the study and were followed for 6 months. Mixed models of repeated measures were used to assess improvements between baseline and month 6, adjusted for relevant confounders.

Results

A total of 527 patients (mean age, 50.2 years, 65% female) were enrolled from US, Canada, France and Italy, and included in the analysis. Mean SDS total score, PHQ-9, PDQ-5 scores decreased by 8.6, 7.4 and 4.7 respectively from baseline to last visit. Mean DSST score improved by 6.5 from baseline to last visit. Patients’ overall functioning and quality of life significantly improved, sick leave days and underproductive days (both absenteeism and presenteeism) decreased over the entire follow up period. The overall incidence of adverse events(AE) was 25%, with the most common AEs being nausea and headache.

Conclusions

The results confirm the effectiveness and good tolerability of vortioxetine in a broad range of patients in routine clinical practice.

Conflict of interest

Dr. Mattingly has served as researcher, consultant or speaker for Akili, Alcobra, Alkermes, Allergan, Axsome, Boehringer, Forum, Genentech, Jansen, Lundbeck, Medgenics, Merck, Neos, NLS Pharma, Otsuka, Reckitt Benckiser, Roche, Sage, Shire, Sunovion, Supe

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

SmCo₅ is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo₅ with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo₅ with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO₂ as a template preventing aggregation and growth of the precursor. The amount of SiO₂ nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo₅ with particle dimension from 740 to 504 nm. As-prepared pure SmCo₅ fine powder obtained from using 2 ml SiO₂ suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m^-1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO₂ NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles.

Local and long-range atomic/magnetic structure of non-stoichiometric spinel iron oxide nanocrystallites

Spinel iron oxide nanoparticles of different mean sizes in the range 10-25 nm have been prepared by surfactant-free up-scalable near- and super-critical hydro-thermal synthesis pathways and characterized using a wide range of advanced structural characterization methods to provide a highly detailed structural description. The atomic structure is examined by combined Rietveld analysis of synchrotron powder X-ray diffraction (PXRD) data and time-of-flight neutron powder-diffraction (NPD) data. The local atomic ordering is further analysed by pair distribution function (PDF) analysis of both X-ray and neutron total-scattering data. It is observed that a non-stoichiometric structural model based on a tetragonal γ-Fe2O3 phase with vacancy ordering in the structure (space group P43212) yields the best fit to the PXRD and total-scattering data. Detailed peak-profile analysis reveals a shorter coherence length for the superstructure, which may be attributed to the vacancy-ordered domains being smaller than the size of the crystallites and/or the presence of anti-phase boundaries, faulting or other disorder effects. The intermediate stoichiometry between that of γ-Fe2O3 and Fe3O4 is confirmed by refinement of the Fe/O stoichiometry in the scattering data and quantitative analysis of Mössbauer spectra. The structural characterization is complemented by nano/micro-structural analysis using transmission electron microscopy (TEM), elemental mapping using scanning TEM, energy-dispersive X-ray spectroscopy and the measurement of macroscopic magnetic properties using vibrating sample magnetometry. Notably, no evidence is found of a Fe3O4/γ-Fe2O3 core-shell nanostructure being present, which had previously been suggested for non-stoichiometric spinel iron oxide nanoparticles. Finally, the study is concluded using the magnetic PDF (mPDF) method to model the neutron total-scattering data and determine the local magnetic ordering and magnetic domain sizes in the iron oxide nanoparticles. The mPDF data analysis reveals ferrimagnetic collinear ordering of the spins in the structure and the magnetic domain sizes to be ∼60-70% of the total nanoparticle sizes. The present study is the first in which mPDF analysis has been applied to magnetic nanoparticles, establishing a successful precedent for future studies of magnetic nanoparticles using this technique.

Reduced coronary flow velocity reserve in women with previous pre-eclampsia: link to increased cardiovascular disease risk

OBJECTIVES

To evaluate differences in coronary microvascular function approximately 12 years after delivery between women who had had early- (EO-PE) or late- (LO-PE) onset pre-eclampsia and those who had had a normotensive pregnancy, and to assess the relationship between microvascular function and myocardial deformation at follow-up in these women.

METHODS

This was a case-control study of 88 women who had delivered at the Department of Gynecology and Obstetrics, Randers Regional Hospital, Randers, Denmark, between 1998 and 2008. Coronary flow velocity reserve (CFVR) was assessed by Doppler echocardiography approximately 12 years after delivery. Women were grouped according to whether the pregnancy had been complicated by EO-PE (n = 29) or LO-PE (n = 20), or had been normotensive (controls) (n = 39). Study groups were matched for maternal age and time since delivery. CFVR at follow-up was compared between the study groups. Regression analysis was used to assess the association between gestational age at onset of PE and CFVR. The association between left ventricular global longitudinal strain (LV-GLS) and CFVR at follow-up was also evaluated.

RESULTS

Resting coronary flow velocity assessed 12 years after delivery was comparable between the study groups (P = 0.55), whereas peak hyperemic flow velocity was significantly lower in the EO-PE group than in the LO-PE group (P < 0.01) and controls (P < 0.0001). As such, mean CFVR at follow-up was significantly lower in the EO-PE group than in the LO-PE group (P < 0.01) and controls (P < 0.0001). CFVR was < 2.5 in 48% of women in the EO-PE group, 25% of those in the LO-PE group and 8% of controls (P < 0.01). There was a significant positive association between gestational age at diagnosis of PE and CFVR at 12-year follow-up (β1 = 1.8 (95% CI, 0.8-2.9); P < 0.01). This relationship remained significant after adjustment for cardiovascular risk factors, namely mean arterial blood pressure, glycated hemoglobin level, body mass index, low-density lipoprotein cholesterol level and smoking status (P < 0.05). There was a significant association between LV-GLS and CFVR in women who had had PE (β1 = -1.5 (95% CI, -2.2 to -0.9); R²  = 0.33, P < 0.0001).

CONCLUSIONS

Low gestational age at onset of PE, both as a continuous variable and when categorized as early onset, was associated with decreased CFVR 12 years after delivery. Nearly 50% of women who had had EO-PE had CFVR < 2.5 at follow-up. Reduced CFVR in women who had had PE was associated with subclinical myocardial dysfunction in terms of reduced LV-GLS. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Exploring the direct synthesis of exchange-spring nanocomposites by reduction of CoFe2O4 spinel nanoparticles using in situ neutron diffraction

In situ neutron powder diffraction (NPD) was employed for investigating gram-scale reduction of hard magnetic CoFe2O4 (spinel) nanoparticles into CoFe2O4/CoFe2 exchange-spring nanocomposites via H2 partial reduction. Time-resolved structural information was extracted from Rietveld refinements of the NPD data, revealing significant changes in the reduction kinetics based on the applied temperature and H2 available. The nanocomposite formation was found to take place via the following two-step reduction process: CoxFe3-xO4 → CoyFe1-yO → CozFe2-z. The refined lattice parameters and site occupation fractions indicate that the reduced phases, i.e. CoyFe1-yO and CozFe2-z, initially form as Co-rich compounds (i.e. y > 0.33 and z > 1), which gradually incorporate more Fe as the reduction proceeds. The reduction depletes the Co-content in the parent spinel, which may end up becoming magnetically soft Fe3O4 at high temperature (T = 542 °C), while at lower temperatures there may be a co-existence of Fe3O4 and γ-Fe2O3 or CoxFe3-xO4. The macroscopic magnetic properties of the products were measured by vibrating sample magnetometry (VSM) and revealed the hard and soft magnetic domains in the nanocomposites to be effectively exchange-coupled. An increase of approximately 70% in specific saturation magnetisation, remanence magnetisation, and coercivity compared to the parent CoFe2O4 material was achieved for the best sample.

Elucidating the relationship between nanoparticle morphology, nuclear/magnetic texture and magnetic performance of sintered SrFe12O19 magnets

Several M-type SrFe12O19 nanoparticle samples with different morphologies have been synthesized by different hydrothermal and sol-gel synthesis methods. Combined Rietveld refinements of neutron and X-ray powder diffraction data with a constrained structural model reveal a clear correlation between crystallite size and long-range magnetic order, which influences the macroscopic magnetic properties of the sample. The tailor-made powder samples were compacted into dense bulk magnets (>90% of the theoretical density) by spark plasma sintering (SPS). Powder diffraction as well as X-ray and neutron pole figure measurements and analyses have been carried out on the compacted specimens in order to characterize the nuclear (structural) and magnetic alignment of the crystallites within the dense magnets. The obtained results, combined with macroscopic magnetic measurements, reveal a direct influence of the nanoparticle morphology on the self-induced texture, crystallite growth during compaction and macroscopic magnetic performance. An increasing diameter-to-thickness aspect ratio of the platelet-like nanoparticles leads to increasing degree of crystallite alignment achieved by SPS. Consequently, magnetically aligned, highly dense magnets with excellent magnetic performance (30(3) kJ m-3) are obtained solely by nanostructuring means, without application of an external magnetic field before or during compaction. The demonstrated control over nanoparticle morphology and, in turn, crystal and magnetic texture is a key step on the way to designing nanostructured hexaferrite magnets with optimized performance.

Bounding Global Aerosol Radiative Forcing of Climate Change

Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable, and arguable lines of evidence, including modeling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. However, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of -1.6 to -0.6 W m-2, or -2.0 to -0.4 W m-2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted toward more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.

Correlation between microstructure, cation distribution and magnetism in Ni1−xZnxFe2O4 nanocrystallites

A reliable crystallographic model of Ni_1−xZn_xFe₂O₄ is presented using a combination of different methods; TEM, STEM-HAADF, and powder diffraction data from different sources (in-house, synchrotron and neutron).

Interprofessional collaboration in health promotion: changing tasks as leverage for innovation

Background

Increasing demand for interprofessional collaboration calls for change in organisational practice and interactions of professionals. Health promotion is a particularly interesting area for observing these changes, because it involves professionals with different disciplinary backgrounds usually also working in different sectors. In Denmark new health promotion strategies in organisations were introduced to engage professionals in new tasks and establish interprofessional ways of working. Our research aimed to explore how these strategies impact in professional practices, using a cookery project for children as a case study, which involved care assistants and school teachers.

Methods

A qualitative case study was conducted to investigate how care assistants from a nursing home and school teachers implemented a cookery project in a Danish school; the focus was on joint care and teaching situations among the two professions and their users. Our data consisted of documents, participatory observations, and interviews with professionals; a sociological institutional framework was applied to analyse the data.

Results

Institutional changes and the demand for joint care and teaching activities in the cooking project fostered new interprofessional collaboration. Three themes of new professional activities emerged: 1) ‘interplay’ related to making different generations collaborate on the tasks involved in the cookery session, 2) ‘care’ concerned with caregiving activities, and 3) ‘learning” focused on schooling on healthy food and cooking. The activities were related to traditional and new roles in professional practices of both groups.

Conclusions

Changes in professional practices evolved in an informal manner from new tasks and ‘lived’ experiences in the cookery project. The specific practical tasks of health promotion offer an important leverage for future interprofessional collaborations.

Air-heated solid–gas reaction setup for in situ neutron powder diffraction

The design and function of a reduction furnace, specially designed for solid–gas in situ monochromatic angular dispersive neutron powder diffraction, is presented. The functionality is demonstrated by performing a reduction experiment of CoFe2O4 nanoparticles at the instrument DMC at SINQ. Heating is provided by an air gun, allowing the sample to reach temperatures in the range of 300–973 K within less than 5 min. The setup is based on a single-crystal sapphire tube with one end closed. A φ scan of the tube reveals its single-crystal nature, through strong single-crystal reflections, while the remaining background is very low, uniform and flat. CoFe2O4 was reduced using a time resolution of 8 min and a sample volume of ∼2 cm3. By means of sequential Rietveld refinement of the in situ neutron diffraction data, a two-step reduction mechanism was discovered: CoFe2O4 → Co0.33Fe0.67O → CoFe2. The setup offers high temperatures, fast temperature stability, large sample volumes and respectable time resolution. The setup has proven to be ideal to carry out investigations of advanced materials under realistic conditions. The ability to investigate real materials in real time under realistic conditions may be a significant advantage for scientific investigations as well as for industrial applications.

Laboratory setup for rapid in situ powder X-ray diffraction elucidating Ni particle formation in supercritical methanol

The design and function of a custom-made Soller slit for a laboratory 2D area detector is presented through a series of demonstration images and an in situ experiment following the formation of nickel particles in supercritical methanol. The in situ experiment is performed in a capillary sample environment, modified for a laboratory scale Rigaku Smartlab diffractometer, and with a temperature range of 300-1050 K. The formation of nickel particles was followed successfully using laboratory in situ X-ray powder diffraction with a time resolution in the order of 27 s. Observations from the area detector images showed the appearance of three distinct phases during the reaction: Ni₃(NO₃)₂(OH)₄, NiO, and Ni. The images were linearly integrated and analyzed using Rietveld refinement. A reaction mechanism is proposed based on an evaluation of the weight fractions and scattering factors as a function of reaction time.

Structure and magnetic properties of W-type hexaferrites

W-type hexaferrites (WHFs) (SrMe 2Fe16O27, Me = Mg, Co, Ni and Zn) are hard magnetic materials with high potential for permanent magnet applications owing to their large crystalline anisotropy and high cation tunability. However, little is known with regards to their complex structural and magnetic characteristics. Here, the substitution of metals (Me = Mg, Co, Ni and Zn) in WHFs is described and their crystal and magnetic structures investigated. From joined refinements of X-ray and neutron powder diffraction data, the atomic positions of the Me atoms were extracted along with the magnetic dipolar moment of the individual sites. The four types of WHFs exhibit ferrimagnetic ordering. For Mg, Ni and Zn the magnetic moments are found to be ordered colinearly and with the magnetic easy axis along the crystallographic c axis. In SrCo2Fe16O27, however, the spontaneous magnetization changes from uniaxial to planar, with the moments aligning in the crystallographic ab plane. Macromagnetic properties were measured using a vibration sample magnetometer. The measured saturation magnetization (M s) between the different samples follows the same trend as the calculated M s extracted from the refined magnetic moments of the neutron powder diffraction data. Given the correlation between the calculated M s and the refined substitution degree of the different Me in specific crystallographic sites, the agreement between the measured and calculated M s values consolidates the robustness of the structural and magnetic Rietveld model.

Functional disruption of pyrimidine nucleoside transporter CNT1 results in a novel inborn error of metabolism with high excretion of uridine and cytidine

Genetic defects in the pyrimidine nucleoside transporters of the CNT transporter family have not yet been reported. Metabolic investigations in a patient with infantile afebrile tonic-clonic seizures revealed increased urinary uridine and cytidine excretion. Segregation of this metabolic trait in the family showed the same biochemical phenotype in a healthy older brother of the index. Whole exome sequencing revealed biallelic mutations in SLC28A1 encoding the pyrimidine nucleoside transporter CNT1 in the index and his brother. Both parents and unaffected sibs showed the variant in heterozygous state. The transporter is expressed in the kidneys. Compelling evidence is available for the disrupting effect of the mutation on the transport function thus explaining the increased excretion of the pyrimidine nucleosides. The exome analysis also revealed a pathogenic mutation in PRRT2 in the index, explaining the epilepsy phenotype in infancy. At present, both the index (10 years) and his older brother are asymptomatic. Mutations in SLC28A1 cause a novel inborn error of metabolism that can be explained by the disrupted activity of the pyrimidine nucleoside transporter CNT1. This is the first report describing a defect in the family of CNT concentrative pyrimidine nucleoside transporter proteins encoded by the SLC28 gene family. In all likelihood, the epilepsy phenotype in the index is unrelated to the SLC28A1 defect, as this can be fully explained by the pathogenic PRRT2 variant. Clinical data on more patients are required to prove whether pathogenic mutations in SLC28A1 have any clinical consequences or are to be considered a benign metabolic phenotype.

Optimization of magnetic properties in fast consolidated SrFe12O19 nanocrystallites

The magnetic properties of SrFe₁₂O₁₉ nanocrystallites produced by hydrothermal synthesis and consolidated by Spark Plasma Sintering (SPS) were optimized by varying the compaction parameters: sintering time, sintering temperature, uniaxial pressure or pre-compaction in a magnetic field. Highly textured compacts with a high degree of crystallite alignment were produced. Qualitative and quantitative textural information was obtained based on X-ray diffraction pole figure measurements. The optimum sintering conditions, relating the degree of alignment and bulk magnetic properties, were identified based on the resulting magnetic properties. It was found that one must strike a balance between the degree of crystallite alignment for high saturation magnetisation and coercivity (H _c) to gain the highest energy product (BH_max). It was found that the coercive field drops when the crystallite alignment increases. This was particularly pronounced in the case of magnetically pre-aligned powders prior to SPS, where H _c and BH_max decreased as the pellets became increasingly textured. The best BH_max value of 29(4) kJ m^-3 was found for the sample sintered at 950 °C for 2 minutes with an applied pressure of 100 MPa for a powder pre-aligned in an applied field of 0.55 T. The results presented here show the potential of SPS consolidation of SrFe₁₂O₁₉ with high relative densities and emphasize the effect of the degree of alignment on the decrease of coercive field and its influence on the magnetic performance.

Crystalline and magnetic structure-property relationship in spinel ferrite nanoparticles

Magnetic spinel ferrite MFe2O4 (M = Mn, Co, Ni, Zn) nanoparticles have been prepared via simple, green and scalable hydrothermal synthesis pathways utilizing sub- and supercritical conditions to attain specific product characteristics. The crystal-, magnetic- and micro-structures of the prepared crystallites have been elucidated through meticulous characterization employing several complementary techniques. Analysis of energy dispersive X-ray spectroscopy (EDS) and X-ray absorption near edge structure (XANES) data verifies the desired stoichiometries with divalent M and trivalent Fe ions. Robust structural characterization is carried out by simultaneous Rietveld refinement of a constrained structural model to powder X-ray diffraction (PXRD) and high-resolution neutron powder diffraction (NPD) data. The structural modeling reveals different affinities of the 3d transition metal ions for the specific crystallographic sites in the nanocrystallites, characterized by the spinel inversion degree, x, [M2+1-xFe3+x]tet[M2+xFe3+2-x]octO4, compared to the well-established bulk structures. The MnFe2O4 and CoFe2O4 nanocrystallites exhibit random disordered spinel structures (x = 0.643(3) and 0.660(6)), while NiFe2O4 is a completely inverse spinel (x = 1.00) and ZnFe2O4 is close to a normal spinel (x = 0.166(10)). Furthermore, the size, size distribution and morphology of the nanoparticles have been assessed by peak profile analysis of the diffraction data, transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The differences in nanostructure, spinel inversion and distinct magnetic nature of the M2+ ions directly alter the magnetic structures of the crystallites at the atomic-scale and consequently the macroscopic magnetic properties of the materials. The present study serves as an important structural benchmark for the rapidly expanding field of spinel ferrite nanoparticle research.

Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets

During the past decade, CoFe₂O₄ (hard)/Co-Fe alloy (soft) magnetic nanocomposites have been routinely prepared by partial reduction of CoFe₂O₄ nanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a byproduct of the reduction, although it remains unclear whether the formation of this phase occurs during the reduction itself or at a later stage. Here, a novel reaction cell was designed to monitor the reduction in situ using synchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of the in situ data yielded time-resolved information on the sample composition and confirmed that the monoxide is generated as an intermediate phase. The macroscopic magnetic properties of samples at different reduction stages were measured by means of vibrating sample magnetometry (VSM), revealing a magnetic softening with increasing soft phase content, which was too pronounced to be exclusively explained by the introduction of soft material in the system. The elemental compositions of the constituent phases were obtained from joint Rietveld refinements of ex situ high-resolution PXRD and neutron powder diffraction (NPD) data. It was found that the alloy has a tendency to emerge in a Co-rich form, inducing a Co deficiency on the remaining spinel phase, which can explain the early softening of the magnetic material.

Pitfalls and reproducibility ofin situsynchrotron powder X-ray diffraction studies of solvothermal nanoparticle formation

In situpowder X-ray diffraction (PXRD) is a powerful characterization tool owing to its ability to provide time-resolved information about phase composition, crystal structure and microstructure. The application of high-flux synchrotron X-ray beams and the development of custom-built reactors have facilitated second-scale time-resolved studies of nanocrystallite formation and growth during solvothermal synthesis. The short exposure times required for good time resolution limit the data quality, while the employed high-temperature–high-pressure reactors further complicate data acquisition and treatment. Based on experience gathered during ten years of conductingin situstudies of solvothermal reactions at a number of different synchrotrons, a compilation of useful advice for conductingin situPXRD experiments and data treatment is presented here. In addition, the reproducibility of the employed portablein situPXRD setup, experimental procedure and data analysis is evaluated. This evaluation is based on repeated measurements of an LaB6line-profile standard throughout 5 d of beamtime and on the repetition of ten identicalin situsynchrotron PXRD experiments on the hydrothermal formation of γ-Fe2O3nanocrystallites. The study reveals inconsistencies in the absolute structural and microstructural values extracted by Rietveld refinement and whole powder pattern modelling of thein situPXRD data, but also illustrates the robustness of trends and relative changes in the extracted parameters. From the data, estimates of the effective errors and reproducibility ofin situPXRD studies of solvothermal nanocrystallite formation are provided.

Structural evolution and stability of Sc2(WO4)3 after discharge in a sodium-based electrochemical cell

Sc₂(WO₄)₃, prepared by solid state synthesis and constructed as an electrode, is discharged to different states in half-cell batteries, versus a Na negative electrode. The structural evolution of the Na-containing electrodes is studied with synchrotron powder X-ray diffraction (PXRD) revealing an increase in microstrain and a gradual amorphization taking place with increasing Na content in the electrode. This indicates that a conversion reaction takes place in the electrochemical cell. X-ray absorption spectroscopy (XAS) at the tungsten L3 absorption edge shows a reduction in the tungsten oxidation state. Variable temperature (VT) PXRD shows that the Sc₂(WO₄)₃ electrode remains relatively stable at higher temperatures, while the Na-containing samples undergo a number of phase transitions and/or turn amorphous above ∼400 °C. Although, Sc₂(WO₄)₃ is a negative thermal expansion (NTE) material only a subtle change of the thermal expansion is found below 400 °C for the Na-containing electrodes. This work shows the complexity in employing an electrochemical cell to produce Na-containing Sc₂(WO₄)₃ and the subsequent phase transitions.