Order-disorder and ionic conductivity in calcium nitride-hydride

Prof John TS Irvine and Prof Martin Owen Jones: STFC 5005—Development of Combined In situ Neutron Diffraction and Electrochemical Studies.Recently nitrogen-hydrogen compounds have successfully been applied as co-catalysts for mild conditions ammonia synthesis. Ca2NH was shown to act as a H2 sink during reaction, with H atoms from its lattice being incorporated into the NH3(g) product. Thus the ionic transport and diffusion properties of the N–H co-catalyst are fundamentally important to understanding and developing such syntheses. Here we show hydride ion conduction in these materials. Two distinct calcium nitride-hydride Ca2NH phases, prepared via different synthetic paths are found to show dramatically different properties. One phase (β) shows fast hydride ionic conduction properties (0.08 S/cm at 600 °C), on a par with the best binary ionic hydrides and 10 times higher than CaH2, whilst the other (α) is 100 times less conductive. An in situ combined analysis techniques reveals that the effective β-phase conducts ions via a vacancy-mediated phenomenon in which the charge carrier concentration is dependent on the ion concentration in the secondary site and by extension the vacancy concentration in the main site.Publisher PDFPeer reviewe

Strengthening Uganda's policy environment for investing in university development

The authors examine the policy environment for investment in university development in Uganda, with special attention to the needs of Makerere University. They present data on the structure and financing of higher education, which gets a high priority in government educational spending. A second public university and new private universities have been established since 1986, but Makerere accounts for most university enrollment and government spending on higher education and it trains most of the country's high-level professional and technical manpower. Its revitalization after many years of neglect is central to government and donor plans for investment in human resource development. The authors emphasize how continuing austerity affects staff retention and staff engagement in academic work, as well as the quality of programs Makerere offers. They present a strategy for university development that involves establishing policy structures to: guide and coordinate investments in higher education as a whole; facilitate the expansion of higher education and the development of diploma-granting institutions to accommodate increasing social demand; and promote cost-saving and revenue-generating activities in the public universities - which would require giving them more autonomy in matters affecting their cost structure and budgeting. Among specific actions they recommend: making better use of public university assets by developing night courses, part-time degree and non-degree programs, and contract training and other income-generating activities; investigating possibilities for better use of university farms and other properties; making more use of existing capacity in public institutions and increasing the capacity of the newly established private universities; strengthening secondary education in science subjects and encouraging more women to study science and technology; coordinating future donor investments so they address the broad needs of Makerere and other universities; and raising incomes of academic and nonacademic university staff members.Teaching and Learning,Curriculum&Instruction,Gender and Education,Tertiary Education,Primary Education

Low-Loss Plasmonic Dielectric Nanoresonators

Material losses in metals are a central bottleneck in plasmonics for many applications. Here we propose and theoretically demonstrate that metal losses can be successfully mitigated with dielectric particles on metallic films, giving rise to hybrid dielectric-metal resonances. In the far field, they yield strong and efficient scattering, beyond even the theoretical limits of all-metal and all-dielectric structures. In the near field, they offer high Purcell factor (>5000), high quantum efficiency (>90%), and highly directional emission at visible and infrared wavelengths. Their quality factors can be readily tailored from plasmonic-like (∼10) to dielectric-like (∼103), with wide control over the individual resonant coupling to photon, plasmon, and dissipative channels. Compared with conventional plasmonic nanostructures, such resonances show robustness against detrimental nonlocal effects and provide higher field enhancement at extreme nanoscopic sizes and spacings. These hybrid resonances equip plasmonics with high efficiency, which has been the predominant goal since the field’s inception. Keywords: light scattering; nanoantennas; Nanoparticles; nonlocality; radiative efficiency; spontaneous emissionUnited States. Army Research Office (Contract W911NF-13-D-0001)National Science Foundation (U.S.) (Grant DMR-1419807)United States. Department of Energy (Grant DE-SC0001299

The effect of exercise hyperpnea on gross efficiency and anaerobic capacity estimates during a 3-min cycle time trial

This study aimed to analyze the effect of exercise-induced hyperpnea on gross efficiency (GE) and anaerobic capacity estimates during a self-paced 3-min supramaximal cycle time trial (TT). Fourteen highly-trained male cyclists performed 7×4-min submaximal stages, a 6-min passive rest, a 3-min TT, a 5-min passive rest, and a 6-min submaximal stage. Three models were based on the 7×4-min linear regression extrapolation method, using (1) the conventional model (7-YLIN); (2) the same 7-YLIN model but correcting for the additional ventilatory cost (i.e., hyperpnea) (7-YLIN-V-cor); and, (3) accounting for linearly declining GE during the TT (7-YLIN-D). The other three models were based on GE from the last submaximal stage, using the conventional model (GELAST) and the same modifications as described for 7+YLIN, i.e., (1) GELAST, (2) GELAST-V-cor, and (3) GELAST-D. The GELAST model generated 18% higher values of anaerobic capacity than the 7-YLIN model (P<0.05). During the TT, the hyperpnea corrected model (i.e., 7-YLIN-V-cor or GELAST-V-cor) generated, compared to the respective conventional model (i.e., 7-YLIN or GELAST), ~0.7 percentage points lower GE and ~11% higher anaerobic capacity (all, P<0.05). The post-TT GE was 1.9 percentage points lower (P<0.001) and the 7-YLIN-D or GELAST-D model generated, compared to the respective conventional model, a lower GE (~1.0 percentage points) and ~17% higher anaerobic capacity during the TT (all, P<0.05). In conclusion, the correction for a declining GE due to hyperpnea during a supramaximal TT resulted in an increased required total metabolic rate and anaerobic energy expenditure compared to the conventional models

Specific inhibition of binding of antistasin and [A103,106,108] antistasin 93–119 to sulfatide (Gal(3-SO4)β1-1Cer) by glycosaminoglycans

AbstractLeech-derived antistasin is a potent anticoagulant and antimetastatic protein that binds sulfatide (Gal(3-SO4)β1-1Cer)and sulfated polysaccharides. In this study, the synthetic fragment [A103,106,108] antistasin 93–119, which corresponds to the carboxyl terminus, showed specific and saturable binding to sulfatide. Binding was competitively blocked by glycosaminoglycans (GAGs) in the order: dextran sulfate 5000 ≅ dextran sulfate 500 0OO > heparin > dermatan sulfate ⪢ chondroitin sulfates A and C. This rank order of inhibitory potency was identical to that observed with whole antistasin. We suggest that residues 93–119 of antistasin represent a critical domain for binding GAGs and sulfated glycolipids

Studies related to antibody fragment (Fab) production in Escherichia coli W3110 fed-batch fermentation processes using multiparameter flow cytometry

Background: Microbiology is important to industry therefore rapid and statistically representative measurements of cell physiological state, proliferation and viability are essential if informed decisions about fermentation bioprocess optimisation or control are to be made, since process performance will depend largely upon the number of metabolically active viable cells. Methods: Samples of recombinant Escherichia coli W3110, containing the gene for the D1.3 anti-lysozyme Fab fragment under the control of the lac based expression system, were taken at various stages from fed-batch fermentation processes and stained with a mixture of bis-(1, 3-dibutylbarbituric acid) trimethine oxonol and propidium iodide (PI/BOX). Where appropriate, measurements of dissolved oxygen tension (DOT), OD600nm and Fab concentration were made. Results: Depending on time of induction the maximum amount of Fab accumulating in the supernatant varied quite markedly from 1 – 4 μgml-1 as did subsequent cell physiological state with respect to PI/BOX staining with a concomitant drop in maximum biomass concentration. Conclusion: Depending on point of induction a 4 fold increase in Fab production could be achieved accompanied by a ~50% drop in maximum biomass concentration but with a higher proportion of viable cells as measured by multi-parameter flow cytometry

Chirped guided-mode resonance biosensor

Advanced biomedical diagnostic technologies fulfill an important role in improving health and well-being in society. A large number of excellent technologies have already been introduced and have given rise to the "lab-on-a-chip" paradigm. Most of these technologies, however, require additional instrumentation for interfacing and readout, so they are often confined to the laboratory and are not suitable for use in the field or in wider clinical practice. Other technologies require a light coupling element, such as a grating coupler or a fiber coupler, which complicates packaging. Here, we introduce a novel biosensor based on a chirped guided-mode resonant grating. The chirped grating combines the sensing function with the readout function by translating spectral information into spatial information that is easily read out with a simple CMOS camera. We demonstrate a refractive index sensitivity of 137 nm/RIU and an extrapolated limit of detection of 267 pM for the specific binding of an immunoglobulin G antibody. The chirped guided-mode resonance approach introduces a new degree of freedom for sensing biomedical information that combines high sensitivity with autonomous operation. We estimate that the cost of components is U.S. $10 or less when mass manufactured, so the technology has the potential to truly transform point-of-care applications

Chirped guided-mode resonance biosensor

Advanced biomedical diagnostic technologies fulfill an important role in improving health and well-being in society. A large number of excellent technologies have already been introduced and have given rise to the "lab-on-a-chip" paradigm. Most of these technologies, however, require additional instrumentation for interfacing and readout, so they are often confined to the laboratory and are not suitable for use in the field or in wider clinical practice. Other technologies require a light coupling element, such as a grating coupler or a fiber coupler, which complicates packaging. Here, we introduce a novel biosensor based on a chirped guided-mode resonant grating. The chirped grating combines the sensing function with the readout function by translating spectral information into spatial information that is easily read out with a simple CMOS camera. We demonstrate a refractive index sensitivity of 137 nm/RIU and an extrapolated limit of detection of 267 pM for the specific binding of an immunoglobulin G antibody. The chirped guided-mode resonance approach introduces a new degree of freedom for sensing biomedical information that combines high sensitivity with autonomous operation. We estimate that the cost of components is U.S. $10 or less when mass manufactured, so the technology has the potential to truly transform point-of-care applications

The Detection of Water Ice in Comet Hale-Bopp

We present spectra of Comet Hale-Bopp (C/1995 01) covering the range 1.4-2.5 micron that were recorded when the comet was 7 AU from the Sun. These show I)road absorption features at 1.5 and 2.05 micron. We show that some, but not all, of this absorption could be matched by an intimate mixture of water ice and a low albedo material such as carbon on the nucleus. However, we recognize that it is more likely that the ice features are produced by scattering from icy grains in the coma. The absence of absorption at 1.65 micron suggests that this ice is probably in the amorphous state. An unidentified additional component may be required to account for the downward slope at the longwavelength end of the spectrum