Nanocrystalline iron at high pressure

X-ray diffraction measurements were performed on nanocrystalline iron up to 46 GPa. For nanocrystalline epsilon-Fe, analysis of lattice parameter data provides a bulk modulus, K, of 179±8 GPa and a pressure derivative of the bulk modulus, K[prime], of 3.6±0.7, similar to the large-grained control sample. The extrapolated zero-pressure unit cell volume of nanocrystalline epsilon-Fe is 22.9±0.2 Å^3, compared to 22.3±0.2 Å^3 for large-grained epsilon-Fe. No significant grain growth was observed to occur under pressure

Symmetry of re-entrant tetragonal phase in Ba1-xNaxFe2As2: Magnetic versus orbital ordering mechanism

Magneto-structural phase transitions in Ba1-xAxFe2As2 (A = K, Na) materials are discussed for both magnetically and orbitally driven mechanisms, using a symmetry analysis formulated within the Landau theory of phase transitions. Both mechanisms predict identical orthorhombic space-group symmetries for the nematic and magnetic phases observed over much of the phase diagram, but they predict different tetragonal space-group symmetries for the newly discovered re-entrant tetragonal phase in Ba1-xNaxFe2As2 (x ~ 0.24-0.28). In a magnetic scenario, magnetic order with moments along the c-axis, as found experimentally, does not allow any type of orbital order, but in an orbital scenario, we have determined two possible orbital patterns, specified by P4/mnc1' and I4221' space groups, which do not require atomic displacements relative to the parent I4/mmm1' symmetry and, in consequence, are indistinguishable in conventional diffraction experiments. We demonstrate that the three possible space groups are however, distinct in resonant X-ray Bragg diffraction patterns created by Templeton & Templeton scattering. This provides an experimental method of distinguishing between magnetic and orbital models

Statin therapy in critical illness : an international survey of intensive care physicians' opinions, attitudes and practice

Background Pleotropic effects of statins on inflammation are hypothesised to attenuate the severity of and possibly prevent the occurrence of the host inflammatory response to pathogen and infection-related acute organ failure. We conducted an international survey of intensive care physicians in Australia, New Zealand (ANZ) and United Kingdom (UK). The aims of the survey were to assess the current prescribing practice patterns, attitudes towards prescribing statin therapy in critically ill patients and opinions on the need for an interventional trial of statin therapy in critically ill patients. Methods Survey questions were developed through an iterative process. An expert group reviewed the resulting 26 items for face and content validity and clarity. The questions were further refined following pilot testing by ICU physicians from Australia, Canada and the UK. We used the online Smart SurveyTM software to administer the survey. Results Of 239 respondents (62 from ANZ and 177 from UK) 58% worked in teaching hospitals; most (78.2%) practised in ‘closed’ units with a mixed medical and surgical case mix (71.0%). The most frequently prescribed statins were simvastatin (77.6%) in the UK and atorvastatin (66.1%) in ANZ. The main reasons cited to explain the choice of statin were preadmission prescription and pharmacy availability. Most respondents reported never starting statins to prevent (65.3%) or treat (89.1%) organ dysfunction. Only a minority (10%) disagreed with a statement that the risks of major side effects of statins when prescribed in critically ill patients were low. The majority (84.5%) of respondents strongly agreed that a clinical trial of statins for prevention is needed. More than half (56.5%) favoured rates of organ failure as the primary outcome for such a trial, while a minority (40.6%) favoured mortality. Conclusions Despite differences in type of statins prescribed, critical care physicians in the UK and ANZ reported similar prescription practices. Respondents from both communities agreed that a trial is needed to test whether statins can prevent the onset of new organ failure in patients with sepsis

Microsurgical testicular sperm extraction for testicular failure: the South African experience and first successful pregnancy

CITATION: Zarrabi, A. D. & Kruger, T. F. 202). Microsurgical testicular sperm extraction for testicular failure : the South African experience and first successful pregnancy. South African Journal of Surgery, 59(2):52-56, doi:10.17159/2078-5151/2021/v59n2a3230.The original publication is available at: http://www.scielo.org.zaBACKGROUND: In men with non-obstructive azoospermia (NOA), biological fatherhood is only possibly by specialised microsurgical sperm retrieval techniques (micro-TESE), only recently introduced to South Africa. This study aimed to analyse the spectrum of causes of NOA and the outcomes of micro-TESE, including live births, following the use of this technique in South Africa METHODS: This was a retrospective review of all micro-TESE cases performed in South Africa by a single surgeon from 2014 to 2018. Data collected prospectively included: patient demographics, preoperative blood results, cause of azoospermia, intraoperative findings and postoperative complications. The primary outcome measured was surgical success of micro-TESE, which was defined as testicular sperm successfully retrieved and cryopreserved. Subsequent live births from assisted reproductive technology (ART) using the cryopreserved sperm were also documented RESULTS: Twenty-six men with NOA underwent micro-TESE between May 2014 and April 2018. Mean preoperative total testosterone level was 12.0 nmol/l (IQR 5.2) and follicle-stimulating hormone level 23.5 IU/l (IQR 15.6). Genetic testing was performed as part of the preoperative work-up in only 10 of the 26 patients. A specific cause of NOA was identified in 9 of the 26 patients and included Klinefelter syndrome (1 patient), Y-chromosome AZFc microdeletion (1 patient), undescended testicles (5 patients) and chemotherapy (2 patients). The average testicular volume was 9.05 ml (IQR 5.6), and the mean duration of surgery 95.8 minutes (IQR 28.0). The overall sperm retrieval rate was 34.6%. A single pregnancy and subsequent live birth were recorded from a total of eight cycles of intracytoplasmic sperm injection (ICSI): four female partners had one ICSI cycle each and two females underwent two cycles each. Frozen and thawed sperm was used in seven of the ICSI cycles and fresh sperm in one cycle CONCLUSION: In this South African series, sperm retrieval rates of micro-TESE for non-obstructive azoospermia were comparable to those reported internationally. Preoperative genetic testing should be increased to optimise the selection of surgical candidatesPublisher's versio

Produção e avaliação da qualidade de sementes de arroz irrigado.

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