Salicylaldehyde hydrazones: buttressing of outer sphere hydrogen-bonding and copper-extraction properties

Salicylaldehyde hydrazones are weaker copper extractants than their oxime derivatives, which are used in hydrometallurgical processes to recover ~20 % of the world’s copper. Their strength, based on the extraction equilibrium constant Ke, can be increased by nearly three orders of magnitude by incorporating electron-withdrawing or hydrogen-bond acceptor groups (X) ortho to the phenolic OH group of the salicylaldehyde unit. Density functional theory calculations suggest that the effects of the 3-X substituents arise from a combination of their influence on the acidity of the phenol in the pH-dependent equilibrium, Cu2+ + 2Lorg ⇌ [Cu(L–H)2]org + 2H+, and on their ability to ‘buttress’ interligand hydrogen bonding by interacting with the hydrazone N–H donor group. X-ray crystal structure determination and computed structures indicate that in both the solid state and the gas phase, coordinated hydrazone groups are less planar than coordinated oximes and this has an adverse effect on intramolecular hydrogen-bond formation to the neighbouring phenolate oxygen atoms

Tourniquets for the use of total knee arthroplasty : are patients aware of the risks?

Background: Tourniquets are routinely used in total knee arthroplasty (TKA) with an estimated use by up to 93% of surgeons. Advantages include the ability to provide a bloodless field of view to facilitate cement application and increase the success of the procedure. Overall reduction in blood loss is another perceived advantage; however recent research has demonstrated no measurable reduction and conversely a substantial increase in complications such as deep vein thrombosis and systemic emboli. Given the significant complications of tourniquet use we aim to identify patients' views on tourniquets and of emphasis their awareness of the possible risks involved prior to the procedure. Method: A questionnaire - based study was carried out on 35 patients attending an elective orthopaedic centre for TKA surgery. Ethical approval was granted by NRES committee - East of England (REC Ref: 14/EE/1265). Patients were provided with an information sheet detailing the reasons for the tourniquet use and the associated risks and benefits. They were then provided with a questionnaire to ascertain their views and previous understanding of the subject. Simple statistical measures were implemented to analyse the data. Results: Only 32% of patients were aware of the use of tourniquets during the operation. 19% were aware of the benefits prior to reading the information sheet provided with 29% understanding the risks involved prior to their procedure. Finally we found 97% of patients would like more information on the use of tourniquets preoperatively. Conclusion: Tourniquets are widely used in TKA surgery; however, they carry significant risks which are not clearly relayed preoperatively to all patients. Given that 91,000 TKA operations are performed per year we believe it is of paramount importance that all patients are appropriately counselled on the risks and benefits of its use and fully informed consent, including risks of tourniquet use, should be obtained prior to the procedure

Knowledge of the Quantum Domain: An Overlap Strategy

The existence of multiple interpretations of quantum mechanics appears to pose a serious challenge for knowledge claims about the quantum domain. Hoefer (2020) argues that a scientific realist epistemology must be abandoned in this context, while Callender (2020) argues that the realist’s only option is to break the underdetermination between rival interpretations by appealing to extra-empirical virtues. We develop a different response to the quantum underdetermination problem based on identifying statements about the unobservable which all the major ontic interpretations of quantum mechanics agree on. It is commonly believed that Everettian, Bohmian and GRW quantum mechanics share nothing but empirical content. We argue that, while they say very different things about the fundamental nature of quantum systems, they can be understood as agreeing on a plethora of more abstract theoretical claims. In our view, focusing on this descriptive overlap represents the most promising strategy for defending knowledge claims in the quantum domain. We close by considering how this overlap strategy relates to working posits formulations of scientific realism

La Proteómica como vía para determinar el origen animal de los productos cárnicos

Comunicaciones a congreso

Thermal noise in interferometric gravitational wave detectors due to dielectric optical coatings

We report on thermal noise from the internal friction of dielectric coatings made from alternating layers of Ta2O5 and SiO2 deposited on fused silica substrates. We present calculations of the thermal noise in gravitational wave interferometers due to optical coatings, when the material properties of the coating are different from those of the substrate and the mechanical loss angle in the coating is anisotropic. The loss angle in the coatings for strains parallel to the substrate surface was determined from ringdown experiments. We measured the mechanical quality factor of three fused silica samples with coatings deposited on them. The loss angle of the coating material for strains parallel to the coated surface was found to be (4.2 +- 0.3)*10^(-4) for coatings deposited on commercially polished slides and (1.0 +- 0.3)*10^{-4} for a coating deposited on a superpolished disk. Using these numbers, we estimate the effect of coatings on thermal noise in the initial LIGO and advanced LIGO interferometers. We also find that the corresponding prediction for thermal noise in the 40 m LIGO prototype at Caltech is consistent with the noise data. These results are complemented by results for a different type of coating, presented in a companion paper.Comment: Submitted to LSC (internal) review Sept. 20, 2001. To be submitted to Phys. Lett.