Digital technology: coming of age?

Editoria

The effect of magnesium on the local structure and initial dissolution rate of simplified UK Magnox waste glasses

A series of simplified glasses were prepared to mimic the United Kingdom’'s Magnox radioactive waste glasses and determine the separate effect of the presence of Mg on the glass structure and the initial dissolution rate. These glasses had an alkaline earth (Ca/Mg) content of 6.5 mol% and relative ratios of Si, B and Na similar to 25 wt% waste loaded Magnox waste glass simulant. Each simplified glass had similar macroscopic properties, differing only in Ca/Mg ratio. 25Mg magic angle spinning nuclear magnetic resonance (MASNMR) spectra of the simplified Mg endmember (MgEM) glass (with no Ca) and the full-component simulant glass were similar, consistent with the similar Mg local environments in both glasses. 11B MASNMR spectra of the series of simplified glasses showed a systematic increase in the amount of three-coordinated boron ([3]B) with increasing amounts of Mg. A clear change in the charge balancing of four-coordinated boron ([4]B) by Mg compared with Ca is observed. However, 11B NMR measurements of the leached material showed that the additional [3]B was not preferentially leached from the Mg containing samples. Despite the structural changes in the glass induced by Ca/Mg substitution, initial dissolution rates (r0) remained invariant, within error, with Ca/Mg ratio. This indicates that the poorer aqueous durability of Mg-containing Magnox waste glass measured experimentally in long-term leaching experiments, compared with SON68 glass containing Ca, is not caused by a primary structural effect in the glass.R. Guo acknowledges the EPSRC and the University of Cambridge for an International Doctoral Scholarship. A portion of this work was funded by Radioactive Waste Management Limited (C.T. Brigden, S.W. Swanton and I. Farnan). The UK 850 MHz solid-state NMR Facility used in this research was funded by EPSRC and BBSRC (contract reference PR140003), as well as the University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF). Collaborative assistance from the 850 MHz Facility Manager (Dinu Iuga, University of Warwick) is acknowledged

Safe and effective use of lithium

Lithium has proven efficacy in the treatment of bipolar disorder, both for acute mania and long-term mood stabilisation and prophylaxis. It is also useful in combating treatment-resistant depression. Compared to other mood stabilisers, lithium has a favourable efficacy-tolerability balance. Lithium is underused due to active marketing of alternatives and concerns regarding adverse effects, tolerability, and the perception that regular monitoring is difficult

Two-dimensional photocatalyst design: A critical review of recent experimental and computational advances

In recent years, two-dimensional (2D) semiconductor photocatalysts have been widely applied in water splitting, CO2 reduction, N2 fixation, as well as many other important photoreactions. Photocatalysts in the form of 2D nanosheet possess many inherent advantages over traditional 3D nanopowder photocatalysts, including improved light absorption characteristics, shorter electron and hole migration paths to the photocatalysts’ surface (thus minimizing undesirable electron-hole pair recombination), and abundant surface defects which allow band gap modulation and facilitate charge transfer from the semiconductor to adsorbates. When synergistically exploited and optimized, these advantages can impart 2D photocatalysts with remarkable activities relative to their 3D counterparts. Accordingly, a wide range of experimental approaches is now being explored for the synthesis of 2D photocatalysts, with computational methods increasingly being used for identification of promising new 2D photocatalytic materials. Herein, we critically review recent literatures related to 2D photocatalyst development and design. Particular emphasis is placed on 2D photocatalyst synthesis and the importance of computational studies for the fundamental understanding of 2D photocatalyst electronic structure, band gap structure, charge carrier mobility and reaction pathways. We also explore the practical challenges of using 2D photocatalysts, such as their difficulty to synthesize in large quantity and also their characterization. The overarching aim of this review is to provide a snapshot of recent work targeting high-performance 2D photocatalysts for efficient solar energy conversion, thus laying a firm base for future advancements in this rapidly expanding area of photocatalysis research

Nail-biting stuff? The effect of N-acetyl cysteine on nail-biting

N-acetyl cysteine (NAC) is a widely available nutraceutical with a variety of actions. As a precursor of cysteine and glutathione, it has antioxidant properties that may impact on mood and contribute to an effect on impulsivity and obsessive behaviour. Via its additional effect on glutamate via the cystine-glutamate exchange system, NAC has been shown to mediate impulsivity in preclinical models of addiction, reduce craving, and cue extinction. Further, by boosting glutathione, NAC acts as a potent antioxidant and has been shown in two positive, large-scale randomized placebo-controlled trials to affect negative symptoms in schizophrenia and depression in bipolar disorder. We describe three cases in which its actions specifically on nail-biting and associated anxiety may offer a potential treatment. The spontaneous findings are reported as part of an ongoing treatment trial examining the utility of NAC in bipolar disorder. Its actions, if robustly replicated, also point to potential treatment targets in glutathione or glutamate pathways in the brain.<br /

The validity and internal structure of the bipolar depression rating scale (BDRS): data from a clinical trial of N-acetylcysteine as adjunctive therapy in bipolar disorder

Background: The phenomenology of unipolar and bipolar disorders differ in a number of ways, such as the presence of mixed states and atypical features. Conventional depression rating instruments are designed to capture the characteristics of unipolar depression and have limitations in capturing the breadth of bipolar disorder.Method: The Bipolar Depression Rating Scale (BDRS) was administered together with the Montgomery Asberg Rating Scale (MADRS) and Young Mania Rating Scale (YMRS) in a double-blind randomised placebo-controlled clinical trial of N-acetyl cysteine for bipolar disorder (N = 75).Results: A factor analysis showed a two-factor solution: depression and mixed symptom clusters. The BDRS has strong internal consistency (Cronbach\u27s alpha = 0.917), the depression cluster showed robust correlation with the MADRS (r = 0.865) and the mixed subscale correlated with the YMRS (r = 0.750).Conclusion: The BDRS has good internal validity and inter-rater reliability and is sensitive to change in the context of a clinical trial.<br /

Colloquium : disclination loops, point defects, and all that in nematic liquid crystals

The homotopy theory of topological defects is a powerful tool for organizing and unifying many ideas across a broad range of physical systems. Recently, experimental progress was made in controlling and measuring colloidal inclusions in liquid crystalline phases. The topological structure of these systems is quite rich but, at the same time, subtle. Motivated by experiment and the power of topological reasoning, the classification of defects in uniaxial nematic liquid crystals was reviewed and expounded upon. Particular attention was paid to the ambiguities that arise in these systems, which have no counterpart in the much-storied XY model or the Heisenberg ferromagnet

Impact of an Irreversibly Adsorbed Layer on Local Viscosity of Nanoconfined Polymer Melts

We report the origin of the effect of nanoscale confinement on the local viscosity of entangled polystyrene (PS) films at temperatures far above the glass transition temperature. By using marker x-ray photon correlation spectroscopy with gold nanoparticles embedded in the PS films prepared on solid substrates, we have determined the local viscosity as a function of the distance from the polymer-substrate interface. The results show the impact of a very thin adsorbed layer ( 7 nm in thickness) even without specific interactions of the polymer with the substrate, overcoming the effect of a surface mobile layer at the air-polymer interface and thereby resulting in a significant increase in the local viscosity as approaching the substrate interface.T. K. acknowledges the financial support from NSF Grant No. CMMI-084626. Uses of the Advanced Photon Source and the National Synchrotron Light Source were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contracts No. DE-AC02- 06CH11357 and No. DE-AC02-98CH10886, respectively

Solution of the Roth-Marques-Durian Rotational Abrasion Model

We solve the rotational abrasion model of Roth, Marques and Durian (arXiv:1009.3492), a one-dimensional quasilinear partial differential equation resembling the inviscid Burgers equation with the unusual feature of a step function factor as a coefficient. The complexity of the solution is primarily in keeping track of the cases in the piecewise function that results from certain amputation and interpolation processes, so we also extract from it a model of an evolving planar tree graph that tracks the evolution of the coarse features of the contour.Comment: 5 pages, 4 figure