Influence of acoustic cavitation on the controlled ultrasonic dispersion of carbon nanotubes.

Ultrasonication is the most widely used technique for the dispersion of a range of nanomaterials, but the intrinsic mechanism which leads to stable solutions is poorly understood with procedures quoted in the literature typically specifying only extrinsic parameters such as nominal electrical input power and exposure time. Here we present new insights into the dispersion mechanism of a representative nanomaterial, single-walled carbon nanotubes (SW-CNTs), using a novel up-scalable sonoreactor and an in situ technique for the measurement of acoustic cavitation activity during ultrasonication. We distinguish between stable cavitation, which leads to chemical modification of the surface of the CNTs, and inertial cavitation, which favors CNT exfoliation and length reduction. Efficient dispersion of CNTs in aqueous solution is found to be dominated by mechanical forces generated via inertial cavitation, which in turn depends critically on surfactant concentration. This study highlights that careful measurement and control of cavitation rather than blind application of input power is essential in the large volume production of nanomaterial dispersions with tailored properties

Research and theory for nursing and midwifery: Rethinking the nature of evidence

Background and Rationale: The rise in the principles of evidence-based medicine in the 1990s heralded a re-emerging orthodoxy in research methodologies. The view of the randomised controlled trial (RCT) as a “gold standard” for evaluation of medical interventions has extended recently to evaluation of organisational forms and reforms and of change in complex systems—within health care and in other human services. Relatively little attention has been given to the epistemological assumptions underlying such a hierarchy of research evidence. Aims and Methods: Case studies from research in maternity care are used in this article to describe problems and limitations encountered in using RCTs to evaluate some recent policy-driven and consumer-oriented developments. These are discussed in relation to theory of knowledge and the epistemological assumptions, or paradigms, underpinning health services research. The aim in this discussion is not to advocate, or to reject, particular approaches to research but to advocate a more open and critical engagement with questions about the nature of evidence. Findings and Discussion: Experimental approaches are of considerable value in investigating deterministic and probabilistic cause and effect relationships, and in testing often well-established but unevaluated technologies. However, little attention has been paid to contextual and cultural factors in the effects of interventions, in the culturally constructed nature of research questions themselves, or of the data on which much research is based. More complex, and less linear, approaches to methodology are needed to address these issues. A simple hierarchical approach does not represent the complexity of evidence well and should move toward a more cyclical view of knowledge development

High-resolution hydraulic parameter maps for surface soils in tropical South America

Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded data sets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten–Mualem and van Genuchten–Burdine soil hydraulic models, which are widely used hydraulic sub-models in land surface models. This has been possible through interpolating soil measurements from several sources through the <i>SOTERLAC</i> soil and terrain data base and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20x higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally parameterised and that are not just based on soil texture. We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models

Sonocrystallisation of ZIF-8 in water with high excess of ligand: Effects of frequency, power and sonication time

A systematic study on the sonocrystallisation of ZIF-8 (zeolitic imidazolate framework-8) in a water-based system was investigated under different mixing speeds, ultrasound frequencies, calorimetric powers and sonication time. Regardless of the synthesis technique, pure crystals of ZIF-8 with high BET (Brunauer, Emmett and Teller) specific surface area (SSA) can be obtained in water after only 5 s. Furthermore, 5 s sonication produced even smaller crystals (~0.08 µm). The type of technique applied for producing the ZIF-8 crystals did not have any significant impact on crystallinity, purity and yield. Crystal morphology and size were affected by the use of ultrasound and mixing, obtaining nanoparticles with a more spherical shape than in silent condition (no ultrasound and mixing). However, no specific trends were observed with varying frequency, calorimetric power and mixing speed. Ultrasound and mixing may have an effect on the nucleation step, causing the fast production of nucleation centres. Furthermore, the BET SSA increased with increasing mixing speed. With ultrasound, the BET SSA is between the values obtained under silent condition and with mixing. A competition between micromixing and shockwaves has been proposed when sonication is used for ZIF-8 production. The former increases the BET SSA, while the latter could be responsible for porosity damage, causing a decrease of the surface area. © 2021 The Author(s

Hydrological processes and water resources management in a dryland environment II: Surface redistribution of rainfall within fields

International audienceSoil water movement was studied within fields on two different soil types, a red clay soil and a duplex soil of sand over clay, at the Romwe Catchment in southern Zimbabwe. Each study site comprised two fields and formed a surface water sub-catchment (1.0-2.4 ha) from which runoff was gauged. Soil moisture was measured in-situ at up to 20 locations within each sub-catchment over an entire cropping season and the following dry season. Maize was cultivated at both sites according to the farmers' normal cropping practice and crop yields were recorded. Surface redistribution of rainfall through localised runon and runoff was shown to be an important process in both sub-catchments with rainfall concentration factors between 0.2 and 2.7 for major rainfall events. This process was a key factor controlling deep drainage to groundwater. Results indicate that surface water redistribution is of particular importance for groundwater recharge in years with low or evenly distributed rainfall, when it would not otherwise have occurred. The soil water conditions created by surface redistribution of rainfall are also actively exploited by farmers who vary cropping practices within fields to maximise crop yields and reduce the risks of crop failure

Support to woman by a companion of her choice during childbirth: a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>To evaluate the effectiveness and safety of the support given to women by a companion of their choice during labor and delivery.</p> <p>Methods</p> <p>A total of 212 primiparous women were enrolled in a randomized controlled clinical trial carried out between February 2004 and March 2005. One hundred and five women were allocated to the group in which support was permitted and 107 to the group in which there was no support. Variables regarding patient satisfaction and events related to obstetrical care, neonatal results and breastfeeding were evaluated. Student's t-test or Wilcoxon's test, chi-square or Fisher's exact test, risk ratios, and their respective 95% confidence intervals were used in the statistical analysis.</p> <p>Results</p> <p>Overall, the women in the support group were more satisfied with labor (median 88.0 versus 76.0, p < 0.0001) and delivery (median 91.4 versus 77.1, p < 0.0001). During labor, patient satisfaction was associated with the presence of a companion (RR 8.06; 95%CI: 4.84 – 13.43), with care received (RR 1.11; 95%CI: 1.01 – 1.22) and with medical guidance (RR 1.14 95%CI: 1.01 – 1.28). During delivery, satisfaction was associated with having a companion (RR 5.57, 95%CI: 3.70 – 8.38), with care received (RR 1.11 95%CI: 1.01 – 1.22) and with vaginal delivery (RR 1.33 95%CI:1.02 – 1.74). The only factor that was significantly lower in the support group was the occurrence of meconium-stained amniotic fluid (RR 0.51; 95%CI: 0.28 – 0.94). There was no statistically significant difference between the two groups with respect to any of the other variables.</p> <p>Conclusion</p> <p>The presence of a companion of the woman's choice had a positive influence on her satisfaction with the birth process and did not interfere with other events and interventions, with neonatal outcome or breastfeeding.</p

Comparison of cavitation intensity in water and in molten aluminium using a high-temperature cavitometer

The application of ultrasound to industrial casting processes has attracted research interest during the last 50 years. However, the transfer and scale-up of this advanced and promising technology to the industry have been hindered by difficulties in treating large volumes of liquid metal due to the lack of understanding of certain fundamentals. In the current study, experimental results on ultrasonic processing in deionised water and in liquid aluminium (Al) are reported. Cavitation activity was determined in both liquid environments using an advanced high-temperature cavitometer sensor. In water, the highest cavitation activity is obtained for the lowest sonotrode tip amplitudes. Below the sonotrode, the cavitation intensity in liquid aluminium is found to be four times higher than in water.Ultramelt Project financially supported by the EPSRC grants EP/K005804/1 and EP/K00588X/

Assessment of funnel plot asymmetry and publication bias in reproductive health meta-analyses: an analytic survey

BACKGROUND: Despite efforts to assure high methodological standards, systematic reviews may be affected by publication bias. The objective of this study was to evaluate the occurrence of publication bias in a collection of high quality systematic reviews on reproductive health. METHODS: Systematic reviews included in the Reproductive Health Library (RHL), issue No 9, were assessed. Funnel plot was used to assess meta-analyses containing 10 or more trials reporting a binary outcome. A funnel plot, the estimated number of missing studies and the adjusted combined effect size were obtained using the "trim and fill method". Meta-analyses results that were not considered to be robust due to a possible publication bias were submitted to a more detailed assessment. RESULTS: A total of 21 systematic reviews were assessed. The number of trials comprising each one ranged from 10 to 83 (median = 13), totaling 379 trials, whose results have been summarized. None of the reviews had reported any evaluation of publication bias or funnel plot asymmetry. Some degree of asymmetry in funnel plots was observed in 18 of the 21 meta-analyses evaluated (85.7%), with the estimated number of missing studies ranging from 1 to 18 (median = 3). Only for three meta-analyses, the conclusion could not be considered robust due to a possible publication bias. CONCLUSION: Asymmetry is a frequent finding in funnel plots of meta-analyses in reproductive health, but according to the present evaluation, less than 15% of meta-analyses report conclusions that would not be considered robust. Publication bias and other sources of asymmetry in funnel plots should be systematically addressed by reproductive health meta-analysts. Next amendments in Cochrane systematic reviews should include this type of evaluation. Further studies regarding the evolution of effect size and publication bias over time in systematic reviews in reproductive health are needed

Evaluation of satisfaction with care in a midwifery unit and an obstetric unit: a randomized controlled trial of low-risk women

Publisher's version, source: http://doi.org/10.1186/s12884-016-0932-x.BACKGROUND Satisfaction with birth care is part of quality assessment of care. The aim of this study was to investigate possible differences in satisfaction with intrapartum care among low-risk women, randomized to a midwifery unit or to an obstetric unit within the same hospital. METHODS Randomized controlled trial conducted at the Department of Obstetrics and Gynecology, Østfold Hospital Trust, Norway. A total of 485 women with no expressed preference for level of birth care, assessed to be at low-risk at onset of spontaneous labor were included. To assess the overall satisfaction with intrapartum care, the Labour and Delivery Satisfaction Index (LADSI) questionnaire, was sent to the participants 6 months after birth. To assess women’s experience with intrapartum transfer, four additional items were added. In addition, we tested the effects of the following aspects on satisfaction; obstetrician involved, intrapartum transfer from the midwifery unit to the obstetric unit during labor, mode of delivery and epidural analgesia. RESULTS Women randomized to the midwifery unit were significantly more satisfied with intrapartum care than those randomized to the obstetric unit (183 versus 176 of maximum 204 scoring points, mean difference 7.2, p = 0.002). No difference was found between the units for women who had an obstetrician involved during labor or delivery and who answered four additional questions on this aspect (mean item score 4.0 at the midwifery unit vs 4.3 at the obstetric unit, p = 0.3). Intrapartum transfer from the midwifery unit to an obstetric unit, operative delivery and epidurals influenced the level of overall satisfaction in a negative direction regardless of allocated unit (p < 0.001). CONCLUSION Low-risk women with no expressed preference for level of birth care were more satisfied if allocated to the midwifery unit compared to the obstetric unit. TRIAL REGISTRATION The trial is registered at www.​clinicaltrials.​gov NCT00857129. Initially released 03/05/2009

The development and application of a new tool to assess the adequacy of the content and timing of antenatal care

Abstract Background: Current measures of antenatal care use are limited to initiation of care and number of visits. This study aimed to describe the development and application of a tool to assess the adequacy of the content and timing of antenatal care. Methods: The Content and Timing of care in Pregnancy (CTP) tool was developed based on clinical relevance for ongoing antenatal care and recommendations in national and international guidelines. The tool reflects minimal care recommended in every pregnancy, regardless of parity or risk status. CTP measures timing of initiation of care, content of care (number of blood pressure readings, blood tests and ultrasound scans) and whether the interventions were received at an appropriate time. Antenatal care trajectories for 333 pregnant women were then described using a standard tool (the APNCU index), that measures the quantity of care only, and the new CTP tool. Both tools categorise care into 4 categories, from ‘Inadequate’ (both tools) to ‘Adequate plus’ (APNCU) or ‘Appropriate’ (CTP). Participants recorded the timing and content of their antenatal care prospectively using diaries. Analysis included an examination of similarities and differences in categorisation of care episodes between the tools. Results: According to the CTP tool, the care trajectory of 10,2% of the women was classified as inadequate, 8,4% as intermediate, 36% as sufficient and 45,3% as appropriate. The assessment of quality of care differed significantly between the two tools. Seventeen care trajectories classified as ‘Adequate’ or ‘Adequate plus’ by the APNCU were deemed ‘Inadequate’ by the CTP. This suggests that, despite a high number of visits, these women did not receive the minimal recommended content and timing of care. Conclusions: The CTP tool provides a more detailed assessment of the adequacy of antenatal care than the current standard index. However, guidelines for the content of antenatal care vary, and the tool does not at the moment grade over-use of interventions as ‘Inappropriate’. Further work needs to be done to refine the content items prior to larger scale testing of the impact of the new measure