Formation of porous surface layers in reaction bonded silicon nitride during processing

An effort was undertaken to determine if the formation of the generally observed layer of large porosity adjacent to the as-nitride surfaces of reaction bonded silicon nitrides could be prevented during processing. Isostatically pressed test bars were prepared from wet vibratory milled Si powder. Sintering and nitriding were each done under three different conditions:(1) bars directly exposed to the furnance atmosphere; (2) bars packed in Si powder; (3) bars packed in Si3N4 powder. Packing the bars in either Si of Si3N4 powder during sintering retarded formation of the layer of large porosity. Only packing the bars in Si prevented formation of the layer during nitridation. The strongest bars (316 MPa) were those sintered in Si and nitrided in Si3N4 despite their having a layer of large surface porosity; failure initiated at very large pores and inclusions. The alpha/beta ratio was found to be directly proportional to the oxygen content; a possible explanation for this relationship is discussed

Sub-femtosecond electron bunches created by direct laser acceleration in a laser wakefield accelerator with ionization injection

In this work, we will show through three-dimensional particle-in-cell simulations that direct laser acceleration in laser a wakefield accelerator can generate sub-femtosecond electron bunches. Two simulations were done with two laser pulse durations, such that the shortest laser pulse occupies only a fraction of the first bubble, whereas the longer pulse fills the entire first bubble. In the latter case, as the trapped electrons moved forward and interacted with the high intensity region of the laser pulse, micro-bunching occurred naturally, producing 0.5 fs electron bunches. This is not observed in the short pulse simulation.Comment: AAC 201

Persistent, symptomless, systemic, and seed-borne infection of lettuce by Botrytis cinerea

Experiments are presented which show that Botrytis cinerea, the cause of gray mould disease, is often present in symptomless lettuce plants as a systemic, endophytic, infection which may arise from seed. The fungus was isolated on selective media from surface sterilized sections of roots, stem pieces and leaf discs from symptomless plants grown in a conventional glasshouse and in a spore-free air-flow provided by an isolation propagator. The presence of B. cinerea was confirmed by immuno-labelling the tissues with the Botrytis-specific monoclonal antibody BC-12.CA4. As plants grew, infection spread from the roots to stems and leaves. Surface sterilization of seeds reduced the number of infected symptomless plants. Artificial infection of seedlings with dry conidia increased the rate of infection in some experiments. Selected isolates were genetically finger-printed using microsatellite loci. This confirmed systemic spread of the inoculating isolates but showed that other isolates were also present and that single plants hosted multiple isolates. This shows that B. cinerea commonly grows in lettuce plants as an endophyte, as has already been shown for Primula. If true for other hosts, the endophytic phase may be as important a component of the species population as the aggressive necrotrophic phase

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 volume percent hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high strength specimens and both subsurface and surface flaws in low strength specimens

Microgastrinae (Hymenoptera: Braconidae) parasitizing Epirrita autumnata (Lepidoptera: Geometridae) larvae in Fennoscandia with description of Cotesia autumnatae Shaw, sp. n.

The microgastrine subset of hymenopteran parasitoids of the geometrid Epirrita autumnata is investigated in Fennoscandia. Ecology, including population dynamics, of the moth has been intensively studied in northern and mountainous Finland, Norway and Sweden. Recently supported hypotheses about the causes of its cyclic population dynamics stress the role of parasitoids, while the parasitoid complex with some 15 species is insufficiently known. The complex includes four solitarymicrogastrine species, Protapanteles anchisiades (Nixon), P. immunis (Wesmael), Cotesia salebrosa (Marshall) and C. autumnatae Shaw, sp. n. Here, we provide detailed figures for the latter, which is morphologically close to C. jucunda (Marshall), and describe the species as new to science. We also providemore general habitus figures of the other three species, as well as an identification key for the four species, aiming to aid recognition of these species by ecologists dealingwithmicrogastrine parasitoids of E. autumnata and their alternative geometrid hosts

Electrochemical characterization of systems for secondary battery application Second quarterly report, Aug. - Oct. 1966

Multisweep cyclic voltammetry for electrochemical characterization of systems for secondary battery applicatio

Parental experience of interaction with healthcare professionals during their infant's stay in the neonatal intensive care unit.

OBJECTIVE: To explore the experiences of parents of infants admitted to the neonatal intensive care unit towards interaction with healthcare professionals during their infants critical care. DESIGN: Semi-structured interviews were conducted with parents of critically ill infants admitted to neonatal intensive care and prospectively enrolled in a study of communication in critical care decision making. Interviews were transcribed verbatim and uploaded into NVivo V.10 to manage and facilitate data analysis. Thematic analysis identified themes representing the data. RESULTS: Nineteen interviews conducted with 14 families identified 4 themes: (1) initial impact of admission affecting transition into the neonatal unit; (2) impact of consistency of care, care givers and information giving; (3) impact of communication in facilitating or hindering parental autonomy, trust, parental expectations and interactions; (4) parental perception of respect and humane touches on the neonatal unit. CONCLUSION: Factors including the context of infant admission, interprofessional consistency, humane touches of staff and the transition into the culture of the neonatal unit are important issues for parents. These issues warrant further investigation to facilitate individualised family needs, attachment between parents and their baby and the professional team

How the nursing associate role is viewed by different stakeholders: a qualitative research study

Background: The nursing associate role was created following a review by Health Education England in 2015 that examined nurse education and training so that capacity and improvements could be made to the provision of care in England. Objective: To explore different stakeholder perspectives of how the nursing associate role has been embedded within local healthcare practice. Design: The study was designed to explore and evaluate the role of the nursing associate in practice from the perspectives of those stakeholders who have experience of working with the nursing associate. Setting(s): Online semi-structured interviews. Participants: 9 stakeholder participants who had direct contact with the nursing associate or trainee nursing associate in the practice setting. Methods: A mixed-methods qualitative approach was used, which included a creative methodological approach in the form of photo-elicitation and semi-structured interviews to explore the lived experience of participants. Results: Analysis revealed 2 superordinate themes: (1) the contribution of the nursing associate; (2) real-work perspectives of the role. Conclusions: The findings demonstrated that the role was important to the provision of care, but that there were challenges related to communication, support and education provision throughout the organisations

Attitudes About Extremely Preterm Birth Among Obstetric and Neonatal Health Care Professionals in England: A Qualitative Study

Importance: Variation in attitudes between health care professionals involved in the counseling of parents facing extremely preterm birth (<24 wk gestational age) may lead to parental confusion and professional misalignment. Objective: To explore the attitudes of health care professionals involved in the counseling of parents facing preterm birth on the treatment of extremely preterm infants. Design, Setting, and Participants: This qualitative study used Q methods to explore the attitudes of neonatal nurses, neonatologists, midwives, and obstetricians involved in the care of extremely preterm infants in 4 UK National Health Service perinatal centers between February 10, 2020, and April 30, 2021. Each participating center had a tertiary level neonatal unit and maternity center. Individuals volunteered participation through choosing to complete the study following a presentation by researchers at each center. A link to the online Q study was emailed to all potential participants by local principal investigators. Participants ranked 53 statements about the treatment of extremely preterm infants in an online quasi-normal distribution grid from strongly agree (6) to strongly disagree (-6). Main Outcomes and Measures: Distinguishing factors per professional group (representing different attitudes) identified through by-person factor analysis of Q sort-data were the primary outcome. Areas of shared agreement (consensus) between professional groups were also explored. Q sorts achieving a factor loading of greater than 0.46 (P < .01) on a given factor were included. Results: In total, 155 health care professionals volunteered participation (128 [82.6%] women; mean [SD] age, 41.6 [10.2] years, mean [SD] experience, 14.1 [9.6] years). Four distinguishing factors were identified between neonatal nurses, 3 for midwives, 5 for neonatologists, and 4 for obstetricians. Analysis of factors within and between professional groups highlighted significant variation in attitudes of professionals toward parental engagement in decision-making, the perceived importance of potential disability in decision-making, and the use of medical technology. Areas of consensus highlighted that most professionals disagreed with statements suggesting disability equates to reduced quality of life. The statement suggesting the parents' decision was considered the most important when considering neonatal resuscitation was placed in the neutral (middistribution) position by all professionals. Conclusions and Relevance: The findings of this qualitative study suggest that parental counseling at extremely low gestations is a complex scenario further complicated by the differences in attitudes within and between professional disciplines toward treatment approaches. The development of multidisciplinary training encompassing all professional groups may facilitate a more consistent and individualized approach toward parental engagement in decision-making

Electrical coupling of neuro-ommatidial photoreceptor cells in the blowfly

A new method of microstimulation of the blowfly eye using corneal neutralization was applied to the 6 peripheral photoreceptor cells (R1-R6) connected to one neuro-ommatidium (and thus looking into the same direction), whilst the receptor potential of a dark-adapted photoreceptor cell was recorded by means of an intracellular microelectrode. Stimulation of the photoreceptor cells not impaled elicited responses in the recorded cell of about 20% of the response elicited when stimulating the recorded cell. This is probably caused by gap junctions recently found between the axon terminals of these cells. Stimulation of all 6 cells together yielded responses that were larger and longer than those obtained with stimulation of just the recorded cell, and intensity-response curves that deviated more strongly from linearity. Evidence is presented that the resistance of the axon terminal of the photoreceptor cells quickly drops in response to a light flash, depending on the light intensity. Incorporating the cable properties of the cell body and the axon, the resistance of the gap junctions, and the (adapting) terminal resistance, a theoretical model is presented that explains the measurements well. Finally, it is argued that the gap junctions between the photoreceptor cells may effectively uncouple the synaptic responses of the cells by counteracting the influence of field potentials.