Rapid, room-temperature, solvent-free mechanochemical oxidation of elemental gold into organosoluble gold salts

Gold is highly valued for a wide range of commercial and technological applications but is processed exclusively through highly aggressive and toxic solvents and/or reagents, ultimately yielding water-soluble salts that are difficult to separate from inorganic reaction byproducts. As a result, development of safer, cleaner processes that would enable gold processing in non-aqueous, organic solvent is an attractive technological goal. Here, we describe a methodology that simultaneously avoids aggressive reagents and enables gold extraction into a safe organic solvent. The methodology is based on solventless, mechanochemical oxidation of metallic gold with Oxone® in the presence of tetraalkylammonium halide salts, to directly, rapidly (within 30–60 minutes) and at room temperature convert gold metal into solid salts that are immediately soluble in pure organic solvents and aqueous alcoholic media. The organosoluble gold salts are easily separated from sulfate byproducts by direct extraction into the benign solvent ethyl acetate, which is also easily recycled for re-use, providing a strategy for gold activation and dissolution without any additional reagents for purification, such as cation exchange resins, salts, or chelating agents. Besides enabling direct extraction of gold into an organic solvent, the mechanochemically obtained organosoluble gold salts can also be readily used for further syntheses, as shown here by a two-step one-pot route to prepare air- and moisture-resistant Au(i) salts, and an improved synthesis of gold nanoparticles from bulk gold

A comprehensive study of GRB 070125, a most energetic gamma ray burst

We present a comprehensive multiwavelength analysis of the bright, long duration gamma-ray burst GRB 070125, comprised of observations in $\gamma$-ray, X-ray, optical, millimeter and centimeter wavebands. Simultaneous fits to the optical and X-ray light curves favor a break on day 3.78, which we interpret as the jet break from a collimated outflow. Independent fits to optical and X-ray bands give similar results in the optical bands but shift the jet break to around day 10 in the X-ray light curve. We show that for the physical parameters derived for GRB 070125, inverse Compton scattering effects are important throughout the afterglow evolution. While inverse Compton scattering does not affect radio and optical bands, it may be a promising candidate to delay the jet break in the X-ray band. Radio light curves show rapid flux variations, which are interpreted as due to interstellar scintillation, and are used to derive an upper limit of $2.4 \times 10^{17}$ cm on the radius of the fireball in the lateral expansion phase of the jet. Radio light curves and spectra suggest a high synchrotron self absorption frequency indicative of the afterglow shock wave moving in a dense medium. Our broadband modeling favors a constant density profile for the circumburst medium over a wind-like profile ($R^{-2}$). However, keeping in mind the uncertainty of the parameters, it is difficult to unambiguously distinguish between the two density profiles. Our broadband fits suggest that \event is a burst with high radiative efficiency ($> 60$).Comment: 50 pages, 33 figures, sty file included, Appeared in 20 Aug 2008 edition of Astrophysical Journa

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Traumatic spinal cord injury in Victoria, 2007–2016

Objective: To investigate trends in the incidence and causes of traumatic spinal cord injury (TSCI) in Victoria over a 10-year period. Design, setting, participants: Retrospective cohort study: analysis of Victorian State Trauma Registry (VSTR) data for people who sustained TSCIs during 2007–2016. Main outcomes and measures: Temporal trends in population-based incidence rates of TSCI (injury to the spinal cord with an Abbreviated Injury Scale [AIS] score of 4 or more). Results: There were 706 cases of TSCI, most the result of transport events (269 cases, 38%) or low falls (197 cases, 28%). The overall crude incidence of TSCI was 1.26 cases per 100 000 population (95% CI, 1.17–1.36 per 100 000 population), and did not change over the study period (incidence rate ratio [IRR], 1.01; 95% CI, 0.99–1.04). However, the incidence of TSCI resulting from low falls increased by 9% per year (95% CI, 4–15%). The proportion of TSCI cases classified as incomplete tetraplegia increased from 41% in 2007 to 55% in 2016 (P < 0.001). Overall in-hospital mortality was 15% (104 deaths), and was highest among people aged 65 years or more (31%, 70 deaths). Conclusions: Given the devastating consequences of TSCI, improved primary prevention strategies are needed, particularly as the incidence of TSCI did not decline over the study period. The epidemiologic profile of TSCI has shifted, with an increasing number of TSCI events in older adults. This change has implications for prevention, acute and post-discharge care, and support.Ben Beck, Peter A Cameron, Sandra Braaf, Andrew Nunn, Mark C Fitzgerald, Rodney T Judson, Warwick J Teague, Alyse Lennox, James W Middleton, James E Harrison, Belinda J Gabb

Shifting syndromes: Sex chromosome variations and intersex classifications

The 2006 ‘Consensus statement on management of intersex disorders’ recommended moving to a new classification of intersex variations, framed in terms of ‘disorders of sex development’ or DSD. Part of the rationale for this change was to move away from associations with gender, and to increase clarity by grounding the classification system in genetics. While the medical community has largely accepted the move, some individuals from intersex activist communities have condemned it. In addition, people both inside and outside the medical community have disagreed about what should be covered by the classification system, in particular whether sex chromosome variations and the related diagnoses of Turner and Klinefelter’s syndromes should be included. This article explores initial descriptions of Turner and Klinefelter’s syndromes and their subsequent inclusion in intersex classifications, which were increasingly grounded in scientific understandings of sex chromosomes that emerged in the 1950s. The article questions the current drive to stabilize and ‘sort out’ intersex classifications through a grounding in genetics. Alternative social and historical definitions of intersex – such as those proposed by the intersex activists – have the potential to do more justice to the lived experience of those affected by such classifications and their consequences