Nanoscale electrochemistry of sp2 carbon materials: from graphite and graphene to carbon nanotubes

Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed. This Account advocates the use of emerging electrochemical imaging techniques and confined electrochemical cell formats that have considerable potential to reveal major new perspectives on the intrinsic electrochemical activity of carbon materials, with unprecedented detail and spatial resolution. These techniques allow particular features on a surface to be targeted and models of structure–activity to be developed and tested on a wide range of length scales and time scales. When high resolution electrochemical imaging data are combined with information from other microscopy and spectroscopy techniques applied to the same area of an electrode surface, in a correlative-electrochemical microscopy approach, highly resolved and unambiguous pictures of electrode activity are revealed that provide new views of the electrochemical properties of carbon materials. With a focus on major sp2 carbon materials, graphite, graphene, and single walled carbon nanotubes (SWNTs), this Account summarizes recent advances that have changed understanding of interfacial electrochemistry at carbon electrodes including: (i) Unequivocal evidence for the high activity of the basal surface of highly oriented pyrolytic graphite (HOPG), which is at least as active as noble metal electrodes (e.g., platinum) for outer-sphere redox processes. (ii) Demonstration of the high activity of basal plane HOPG toward other reactions, with no requirement for catalysis by step edges or defects, as exemplified by studies of proton-coupled electron transfer, redox transformations of adsorbed molecules, surface functionalization via diazonium electrochemistry, and metal electrodeposition. (iii) Rationalization of the complex interplay of different factors that determine electrochemistry at graphene, including the source (mechanical exfoliation from graphite vs chemical vapor deposition), number of graphene layers, edges, electronic structure, redox couple, and electrode history effects. (iv) New methodologies that allow nanoscale electrochemistry of 1D materials (SWNTs) to be related to their electronic characteristics (metallic vs semiconductor SWNTs), size, and quality, with high resolution imaging revealing the high activity of SWNT sidewalls and the importance of defects for some electrocatalytic reactions (e.g., the oxygen reduction reaction). The experimental approaches highlighted for carbon electrodes are generally applicable to other electrode materials and set a new framework and course for the study of electrochemical and interfacial processes

Space VLBI Observations of 3C 279 at 1.6 and 5 GHz

We present the first VLBI Space Observatory Programme (VSOP) observations of the gamma-ray blazar 3C 279 at 1.6 and 5 GHz. The combination of the VSOP and VLBA-only images at these two frequencies maps the jet structure on scales from 1 to 100 mas. On small angular scales the structure is dominated by the quasar core and the bright secondary component `C4' located 3 milliarcseconds from the core (at this epoch). On larger angular scales the structure is dominated by a jet extending to the southwest, which at the largest scale seen in these images connects with the smallest scale structure seen in VLA images. We have exploited two of the main strengths of VSOP: the ability to obtain matched-resolution images to ground-based images at higher frequencies and the ability to measure high brightness temperatures. A spectral index map was made by combining the VSOP 1.6 GHz image with a matched-resolution VLBA-only image at 5 GHz from our VSOP observation on the following day. The spectral index map shows the core to have a highly inverted spectrum, with some areas having a spectral index approaching the limiting value for synchrotron self-absorbed radiation of 2.5. Gaussian model fits to the VSOP visibilities revealed high brightness temperatures (>10^{12} K) that are difficult to measure with ground-only arrays. An extensive error analysis was performed on the brightness temperature measurements. Most components did not have measurable brightness temperature upper limits, but lower limits were measured as high as 5x10^{12} K. This lower limit is significantly above both the nominal inverse Compton and equipartition brightness temperature limits. The derived Doppler factor, Lorentz factor, and angle to the line-of-sight in the case of the equipartition limit are at the upper end of the range of expected values for EGRET blazars.Comment: 11 pages, 6 figures, emulateapj.sty, To be published in The Astrophysical Journal, v537, Jul 1, 200

The Design and Use of Digital Technologies in the Context of South–South Migration

The use and design of digital technologies plays an important role in South-South migration, from migrant decision making, orientation and route planning, to integration into host communities and connecting with those left behind. Digital technologies can be leveraged to increase access to opportunities and rights for migrants, thereby boosting migration’s developmental benefits at the interface between migrants and host communities. Yet structural inequalities in migration contexts mean that access and use are almost always socially contingent, often leading to further inequalities. This chapter outlines key themes from the existing literature on migrant use of digital technologies in the context of South-South migration drawing also on new data generated through the MIDEQ Hub

Causes of and alternatives to medication for behaviours that challenge in people with intellectual disabilities: direct care providers' perspectives

Behaviours that challenge (BtC), such as aggression and self-injury, are manifested by many people with intellectual disabilities (ID). National and international guidelines recommend non-pharmacological psychosocial intervention before considering medication to address BtC. Support staff play a pivotal role in the prescription process. Using coproduction, we developed a training programme for support staff, called SPECTROM, to give them knowledge and empower them to question inappropriate prescriptions and ask for the discontinuation of medication if appropriate and instead look for ways to help people with ID when they are distressed without relying on medication. We have presented data from two focus groups that we conducted during the development of SPECTROM: one that included support staff, and another that had service managers and trainers. In these focus groups, we explored participants’ views on the use of medication to address BtC with a particular emphasis on the causes of and alternatives to medication for BtC. Along with the participants’ views, we have also presented how we have addressed these issues in the SPECTROM resources

The role of behaviour problems in screening for mental ill-health in adults with intellectual disability

Depression and anxiety are common conditions in adults with intellectual disabilities (ID) and often coexist with behaviour problems. We examined whether behaviour problems can be used to screen for depression and anxiety in ID. Clinical prediction models (CPM) generated from independent databases supported the utility of the depression screen, especially in severe/profound ID. CPM did not support the utility of the anxiety screen at any ID level. Given the paucity of screening tools to improve ascertainment of mental ill-health in ID, the short depression screen would be clinically useful in identifying those who need to undergo a full diagnostic evaluation

Practice patterns of kidney stone management across European and non-European centers: an in-depth investigation from the European Renal Stone Network (ERSN).

Kidney stones are a common condition in the general population, however, high-quality evidence for its management is scarce. We propose the creation of an international network with the aim of sharing practice patterns and patient data towards an improvement of our knowledge of the disease. Cross-sectional survey. An online survey was circulated through several scientific societies. Items were grouped into six domains. Each center's overall score (OS) was also calculated. Chi square and Mann-Whitney tests were performed for differences across centers. The countries that contributed most were Italy (8.6%), Turkey (6.6%), France and Spain (6.1%). Some type of nutritional work-up was implemented in 62% of centers. A DEXA scan was performed by 46% of centers, whereas some kind of acidification test was performed by 25% of centers. Most centers (80%) implemented blood investigations at least at baseline. With regard to 24-h urine exams, 7 out of 16 were performed by at least 50% of centers. Information on stone composition was collected by 58% of centers. The OS was significantly higher among higher-volume centers compared with lower-volume centers (p = 0.002). Significant differences between EU and non-EU centers were found. Cross-sectional design; no validation on information. Our survey highlights the potential for the creation of a network of centers that could share information in a common database for observational research and for enrollment of patients in interventional trials

θ13\theta_{13} and the Higgs mass from high scale supersymmetry

In the framework in which supersymmetry is used for understanding fermion masses rather than stabilizing the electroweak scale, we elaborate the phenomenological analysis for the neutrino physics. A relatively large $\sin{\theta_{13}}$ is the natural result. The model further predicts vanishingly small CP violation in neutrino oscillations. And $\theta_{23}$ is not necessarily maximal. While the high scale supersymmetry generically results in a Higgs mass of about 141 GeV, our model reduces this mass via introducing SU(2)$_L$ triplet fields which also contribute to neutrino masses.Comment: 13 pages, no figure, revtex4, revised versio

Rural to Urban Migration and Changes in Cardiovascular risk Factors in Tanzania: A Prospective Cohort Study.

High levels of rural to urban migration are a feature of most African countries. Our aim was to investigate changes, and their determinants, in cardiovascular risk factors on rural to urban migration in Tanzania. Men and women (15 to 59 years) intending to migrate from Morogoro rural region to Dar es Salaam for at least 6 months were identified. Measurements were made at least one week but no more than one month prior to migration, and 1 to 3 monthly after migration. Outcome measures included body mass index, blood pressure, fasting lipids, and self reported physical activity and diet. One hundred and three men, 106 women, mean age 29 years, were recruited and 132 (63.2%) followed to 12 months. All the figures presented here refer to the difference between baseline and 12 months in these 132 individuals. Vigorous physical activity declined (79.4% to 26.5% in men, 37.8% to 15.6% in women, p < 0.001), and weight increased (2.30 kg men, 2.35 kg women, p < 0.001). Intake of red meat increased, but so did the intake of fresh fruit and vegetables. HDL cholesterol increased in men and women (0.24, 0.25 mmoll-1 respectively, p < 0.001); and in men, not women, total cholesterol increased (0.42 mmoll-1, p = 0.01), and triglycerides fell (0.31 mmoll-1, p = 0.034). Blood pressure appeared to fall in both men and women. For example, in men systolic blood pressure fell by 5.4 mmHg, p = 0.007, and in women by 8.6 mmHg, p = 0.001. The lower level of physical activity and increasing weight will increase the risk of diabetes and cardiovascular disease. However, changes in diet were mixed, and may have contributed to mixed changes in lipid profiles and a lack of rise in blood pressure. A better understanding of the changes occurring on rural to urban migration is needed to guide preventive measures