Three-dimensional pulsed field gradient NMR measurements of self-diffusion in anisotropic materials for energy storage applications.

Anisotropic battery electrodes that allow enhanced diffusion through the thickness of the electrode can be engineered to improve the rate performance, but direct measurement of 3D diffusion in this pore structure is extremely challenging. To address this, we used 1H and 7Li pulsed field gradient (PFG) NMR to measure anisotropic diffusion in a model porous silicon substrate. We show that NMR spectroscopy can resolve solvent molecules and ions (here, in H2O, DMSO, and the battery electrolyte LIPF6:DC:EMC) in and outside of the pores of the Si substrate, allowing the diffusion coefficients of the ion/molecules in the two components to be individually determined. Exchange between ions/molecules inside and outside of the pores is observed with 1H 2D exchange spectroscopy (EXSY). The pore dimensions can extracted from the diffusivity of the in-pore component and the results are in reasonable agreement with the pore dimensions measured with electron microscopy. Better agreement is obtained for pore diameters; for pore length measurements, exchange between the in-pore and ex-pore solvents should be accounted for. These results suggest that PFG-NMR can serve as a non-destructive characterisation method for both in situ and ex situ analyses of materials ranging from complex battery and supercapacitor electrodes to catalyst supports and tissue scaffolds.

Health and mass unemployment events-developing a framework for preparedness and response.

BACKGROUND: Mass unemployment events are not uncommon yet the impact on health is not well recognised. There is a need for a preparedness and response framework, as exists for other events that threaten population health. METHODS: Framework informed by a narrative review of the impact of mass unemployment on health (studies published in English from 1990 to 2016), and qualitative data from 23 semi-structured interviews with individuals connected to historical national and international events, addressing gaps in published literature on lessons learnt from past responses. RESULTS: Economic and employment shock triggered by mass unemployment events have a detrimental impact on workers, families and communities. We present a public health informed response framework which includes (i) identify areas at risk, (ii) develop an early warning system, (iii) mobilise multi-sector action including health and community, (iv) provision of support across employment, finance and health (v) proportionate to need, (vi) extend support to family members and (vii) communities and (viii) evaluate and learn. CONCLUSION: Mass unemployment events have an adverse impact on the health, financial and social circumstances of workers, families, and communities. This is the first framework for action to mitigate and address the detrimental impact of mass unemployment events on population health.

Sustainability and in situ monitoring in battery development.

The development of improved rechargeable batteries represents a major technological challenge for this new century, as batteries constitute the limiting components in the shift from petrol (gasoline) powered to electric vehicles, while also enabling the use of more renewable energy on the grid. To minimize the ecological implications associated with their wider use, we must integrate sustainability of battery materials into our research endeavours, choosing chemistries that have a minimum footprint in nature and that are more readily recycled or integrated into a full circular economy. Sustainability and cost concerns require that we greatly increase the battery lifetime and consider second lives for batteries. As part of this, we must monitor the state of health of batteries continuously during operation to minimize their degradation. It is thus important to push the frontiers of operando techniques to monitor increasingly complex processes. In this Review, we will describe key advances in both more sustainable chemistries and operando techniques, along with some of the remaining challenges and possible solutions, as we personally perceive them.

Thermally reversible nanoparticle gels with tuneable porosity showing structural colour.

We present colloidal gels formed from dispersions of PEG- and PEG+DNA-coated silica nanoparticles showing structural colour. The PEG- and PEG+DNA-coated silica colloids are functionalized using exclusively covalent bonds in aqueous conditions. Both sets of colloids self-assemble into thermally-reversible colloidal gels with porosity that can be tuned by changing the colloid volume fraction, although the interaction potentials of the colloids in the two systems are different. Confocal microscopy and image analysis tools are used to characteraize the gels' microstructures. Optical reflection spectroscopy is employed to study the underlying gel nanostructure and to characterize the optical response of the gels. X-ray nanotomography is used to visualize the nanoscale phase separation between the colloid-rich gel branches and the colloid-free gel pores. These nanoparticle gels open new routes for creating structural colour where the gel structure is decoupled from the form factor of the individual colloids. This approach can be extended to create unexplored three dimensional macroscale materials with length scales spanning hundreds of nanometers, which has been difficult to achieve using other methods.

Designing disordered materials using DNA-coated colloids of bacteriophage fd and gold.

DNA has emerged as an exciting binding agent for programmable colloidal self-assembly. Its popularity derives from its unique properties: it provides highly specific short-ranged interactions and at the same time it acts as a steric stabilizer against non-specific van der Waals and Coulomb interactions. Because complementary DNA strands are linked only via hydrogen bonds, DNA-mediated binding is thermally reversible: it provides an effective attraction that can be switched off by raising the temperature only by a few degrees. In this article we introduce a new binary system made of DNA-functionalized filamentous fd viruses of ∼880 nm length with an aspect ratio of ∼100, and 50 nm gold nanoparticles (gold NPs) coated with the complementary DNA strands. When quenching mixtures below the melt temperature Tm, at which the attraction is switched on, we observe aggregation. Conversely, above Tm the system melts into a homogenous particulate 'gas'. We present the aggregation behavior of three different gold NP to virus ratios and compare them to a gel made solely of gold NPs. In particular, we have investigated the aggregate structures as a function of cooling rate and determine how they evolve as function of time for given quench depths, employing fluorescence microscopy. Structural information was extracted in the form of an effective structure factor and chord length distributions. Rapid cooling rates lead to open aggregates, while slower controlled cooling rates closer to equilibrium DNA hybridization lead to more fine-stranded gels. Despite the different structures we find that for both cooling rates the quench into the two-phase region leads to initial spinodal decomposition, which becomes arrested. Surprisingly, although the fine-stranded gel is disordered, the overall structure and the corresponding length scale distributions in the system are remarkably reproducible. Such highly porous systems can be developed into new functional materials.

IR near-field spectroscopy and imaging of single Li(x)FePO4 microcrystals.

This study demonstrates the unique capability of infrared near-field nanoscopy combined with Fourier transform infrared spectroscopy to map phase distributions in microcrystals of Li(x)FePO4, a positive electrode material for Li-ion batteries. Ex situ nanoscale IR imaging provides direct evidence for the coexistence of LiFePO4 and FePO4 phases in partially delithiated single-crystal microparticles. A quantitative three-dimensional tomographic reconstruction of the phase distribution within a single microcrystal provides new insights into the phase transformation and/or relaxation mechanism, revealing a FePO4 shell surrounding a diamond-shaped LiFePO4 inner core, gradually shrinking in size and vanishing upon delithiation of the crystal. The observed phase propagation pattern supports recent functional models of LiFePO4 operation relating electrochemical performance to material design. This work demonstrates the remarkable potential of near-field optical techniques for the characterization of electrochemical materials and interfaces.

The effect of interface heterogeneity on zinc metal anode cyclability.

Zinc metal batteries (ZMBs) are promising candidates for low-cost, intrinsically safe, and environmentally friendly energy storage systems. However, the anode is plagued with problems such as the parasitic hydrogen evolution reaction, surface passivation, corrosion, and a rough metal electrode morphology that is prone to short circuits. One strategy to overcome these issues is understanding surface processes to facilitate more homogeneous electrodeposition of zinc by guiding the alignment of electrodeposited zinc. Using Scanning Electrochemical Microscopy (SECM), the charge transport rate on zinc metal anodes was mapped, demonstrating that manipulating electrolyte concentration can influence zinc electrodeposition and solid electrolyte interphase (SEI) formation in ZMBs. Using XPS and Raman spectroscopy, it is demonstrated that an SEI is formed on zinc electrodes at neutral pH, composed primarily of a Zn4(OH)6SO4·xH2O species, its formation being attributed to local pH increases at the interface. This work shows that more extended high-rate cycling can be achieved using a 1 M ZnSO4 electrolyte and that these systems have a reduced tendency for soft shorts. The improved cyclability in 1 M ZnSO4 was attributed to a more homogeneous and conductive interface formed, rather than the bulk electrolyte properties. This experimental methodology for studying metal battery electrodes is transferable to lithium metal and anode-free batteries, and other sustainable battery chemistries such as sodium, magnesium, and calcium.

Correction: The effect of interface heterogeneity on zinc metal anode cyclability.

[This corrects the article DOI: 10.1039/D4TA03165B.].

Clinical outcomes and gestational age based prediction of pneumatosis intestinalis in preterm infants with necrotizing enterocolitis.

BACKGROUND: To determine the clinical implications and gestation age-specific diagnostic predictability of pneumatosis in preterm infants with necrotizing enterocolitis (NEC). METHODS: A retrospective study on abdominal radiographs comparing clinical and radiological information in infants with and without pneumatosis. RESULT: Our findings disproved our hypothesis. Pneumatosis was seen more frequently in infants with higher gestational age [28.4 (26.1-32.4) vs. 26.4 (24.3-29) weeks; p < 0.001] and birth weight [1110 (762-1768) vs. 770 (645-1022) grams; p < 0.001] and were more likely delivered vaginally (39.1% vs. 21.7%, p = 0.01). Portal venous gas was seen frequently on radiographs (10.3% vs. 0%, p < 0.001), but not pneumoperitoneum (20.7% vs. 36.7%, p = 0.02). Infants with pneumatosis frequently developed acute kidney injury, with higher serum creatinine (16.5% vs. 4.5%, p = 0.02) and frequent oliguria (12.9% vs. 2.7 %; p = 0.043) and had higher C-reactive protein levels at 24 and 96 hours (p < 0.002). Receiver operating curves for pneumatosis showed GA >28 weeks and birth weight > 1000 gm to have a sensitivity of 58.6% and specificity of 72.5%. CONCLUSION: Contrary to our hypothesis, infants who developed pneumatosis during NEC were more mature with a higher gestational age and birth weight than those who did not.

Uranium bioaccumulation by a Citrobacter sp. as a result of enzymically mediated growth of polycrystalline HUO2PO4.

A Citrobacter sp. accumulates heavy deposits of metal phosphate, derived from an enzymically liberated phosphate ligand. The cells are not subject to saturation constraints and can accumulate several times their own weight of precipitated metal. This high capacity is attributable to biomineralization; uranyl phosphate accumulates as polycrystalline HUO2PO4 at the cell surface. The precipitated metal is indistinguishable from crystalline HUO2PO4.4H2O grown by chemical methods.

GABA(A) receptors containing (alpha)5 subunits in the CA1 and CA3 hippocampal fields regulate ethanol-motivated behaviors: an extended ethanol reward circuitry.

GABA receptors within the mesolimbic circuitry have been proposed to play a role in regulating alcohol-seeking behaviors in the alcohol-preferring (P) rat. However, the precise GABA(A) receptor subunit(s) mediating the reinforcing properties of EtOH remains unknown. We examined the capacity of intrahippocampal infusions of an alpha5 subunit-selective ( approximately 75-fold) benzodiazepine (BDZ) inverse agonist [i.e., RY 023 (RY) (tert-butyl 8-(trimethylsilyl) acetylene-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5a] [1,4] benzodiazepine-3-carboxylate)] to alter lever pressing maintained by concurrent presentation of EtOH (10% v/v) and a saccharin solution (0.05% w/v). Bilateral (1.5-20 microgram) and unilateral (0.01-40 microgram) RY dose-dependently reduced EtOH-maintained responding, with saccharin-maintained responding being reduced only with the highest doses (e.g., 20 and 40 microgram). The competitive BDZ antagonist ZK 93426 (ZK) (7 microgram) reversed the RY-induced suppression on EtOH-maintained responding, confirming that the effect was mediated via the BDZ site on the GABA(A) receptor complex. Intrahippocampal modulation of the EtOH-maintained responding was site-specific; no antagonism by RY after intra-accumbens [nucleus accumbens (NACC)] and intraventral tegmental [ventral tegmental area (VTA)] infusions was observed. Because the VTA and NACC contain very high densities of alpha1 and alpha2 subunits, respectively, we determined whether RY exhibited a "negative" or "neutral" pharmacological profile at recombinant alpha1beta3gamma2, alpha2beta3gamma2, and alpha5beta3gamma2 receptors expressed in Xenopus oocytes. RY produced "classic" inverse agonism at all alpha receptor subtypes; thus, a neutral efficacy was not sufficient to explain the failure of RY to alter EtOH responding in the NACC or VTA. The results provide the first demonstration that the alpha5-containing GABA(A) receptors in the hippocampus play an important role in regulating EtOH-seeking behaviors.

Retention of maze performance inversely correlates with N-methyl-D-aspartate receptor number in hippocampus and frontal neocortex in the rat.

The N-methyl-D-aspartate (NMDA) receptor may play a critical role in learning and memory. In the present study, a significant correlation was found between the number of NMDA-displaceable, Na+-independent L-[3H]glutamate binding sites in the hippocampus and neocortex of young rats and the mean number of errors during retention, but not acquisition, in a 14-unit T-maze.

Naloxone modulates the behavioral effects of cholinergic agonists and antagonists.

Peripheral glucose administration enhances memory in rodents and humans. Recent findings suggest that glucose may affect behavior, in part, by augmenting central cholinergic functions and by attenuating central opiate functions. The present experiments examined interactions between an opiate antagonist, naloxone, and cholinergic agents to determine whether the effects would parallel those found with glucose. Three behavioral measures were assessed: tremors, hyperactivity, and spontaneous alternation. Naloxone (1 mg/kg) significantly augmented tremors elicited by physostigmine (0.3 mg/kg). Naloxone (1 mg/kg) also attenuated increases in locomotor activity and impairments in spontaneous alternation performance elicited by scopolamine (1 and 3 mg/kg for activity and alternation measures, respectively). Thus, across three diverse measures, naloxone produced effects similar to those previously reported for glucose. These findings are consistent with the hypothesis that release of cholinergic activity from opiate inhibition may contribute to glucose effects on behavior.

High-order spin diffusion mechanisms in (19)F 2-D NMR of oxyfluorides.

Negative cross-peaks have been observed in the (19)F 2-D magnetization-exchange MAS NMR spectra of Ba(2)MoO(3)F(4) under fast-spinning conditions. The polarization transfer dynamics are studied as a function of the spinning frequency and the frequency separation of the resonances. The results are consistent with a novel mechanism, in which four spins simultaneously exchange Zeeman magnetization with each other, in an energy-conserving process.

Optimizing the 13C-14N REAPDOR NMR experiment: a theoretical and experimental study.

The optimum 14N pulse lengths in the 13C-14N rotational-echo adiabatic-passage double-resonance (REAPDOR) NMR experiment are determined from calculations and from experiments on samples of glycine and L-alanine. The REAPDOR experiment utilizes the adiabatic passages that 14N spins make between the 14N Zeeman energy levels during the application of a single, short 14N radiofrequency pulse. Use of a short 14N irradiation time of less than one-quarter of a rotor period ensures that the number of 14N spins that undergo more than one passage is minimized. This simplifies calculations describing 13C dipolar dephasing and provides better agreement between calculations and experiments. Recovery of the 13C-14N dipolar couplings and 14N quadrupolar coupling constants and asymmetry parameters is described.

An evaluation of short-term oxygen therapy: the prescription of oxygen to patients with chronic lung disease hypoxic at discharge from hospital.

The provision of domiciliary oxygen to patients hypoxic at hospital discharge has been termed short-term oxygen therapy (STOT). This practice appears widespread, although there is a paucity of literature and no evidence-based guidelines. We undertook this audit to examine the prescription of STOT and determine the proportion fulfilling for long-term oxygen therapy (LTOT) 2 months post-discharge. STOT was defined prospectively: resting PaO2 < or = 7.3 kPa (55 mmHg) or PaO2 between 7.3 and 8.0 kPa (60 mmHg) with any of the following: clinical evidence of cor pulmonale (pedal oedema or jugular venous distension), ECG evidence of pulmonale, echocardiogram evidence of pulmonary hypertension, haematocrit > 0.55 (adapted directly from LTOT criteria). Patients were evaluated for LTOT 2 months post-discharge when clinically stable on optimal medical management. All referrals to the Auckland Regional Oxygen Service between July 1998 and 1999 were systematically reviewed. The majority 289/405 (71%) of new referrals were for the prescription of STOT/LTOT in patients with chronic lung disease: 160/289 (55%) derived from hospitalized patients with the majority 130 (81%) fulfilling criteria for STOT, median age 73, range 24-96 years. Mean hospital stay was 10.2 days. Two months after discharge 22/127 (17%) of STOT patients had died, comparable with 4/22 (18%) not fulfilling criteria for STOT. A total of 123 patients were assessed for LTOT at 2 months; 76 (62%) fulfilled criteria for LTOT. The prescription of oxygen at hospital discharge represented a considerable proportion of our referral load. There was a high mortality in the 2-month follow-up period. A significant proportion of STOT patients did not subsequently fulfill criteria for LTOT. Further prospective studies are required in order to develop evidence-based guidelines.

Community empowerment paradigm drift and the primary prevention of HIV/AIDS.

Long discussed in the public health arena, the concept of empowerment has only recently entered the discourse on the primary prevention of HIV/AIDS in the United States. Despite its broad appeal, empowerment has not been systematically incorporated into theory-based interventions, which may reflect a lack of consensus on the meaning of empowerment, how to measure it, and the intervention strategies it implies. The purpose of this paper is to consider the relevance of empowerment to community interventions for persons at risk for HIV, particularly women. The origins of empowerment are reviewed; community empowerment as an intervention framework is described and its core assumptions defined. There is some evidence of the growing influence of empowerment and related concepts in recent HIV-related policy, research, and programs funded through the Centers for Disease Control and Prevention. However, adoption of an empowerment framework for HIV prevention will require further theory and measurement development, as well as changes in how public health researchers and practitioners work with the communities they serve.

Vertebral deformity in the thoracic spine in post-menopausal women: value of lumbar spine bone density.

Differential bone loss in the thoracic and lumbar spine is known to occur in some patients with osteoporosis. However, the discriminant value of lumbar spine bone densitometry in the detection of thoracic spine fractures in healthy, population-based women has not been established. The relationship between lumbar spine bone mineral density and thoracic spine vertebral deformities in a prospective study of 79 post-menopausal population-based women aged 45-65 years has been investigated. Lumbar spine bone mineral density was measured using dual energy X-ray absorptiometry, and vertebral morphometry was assessed from lateral thoracic spine radiographs. Seven women (9%) were found to have one or more vertebral deformities in the thoracic spine (reduction in anterior or posterior height > 25%). Only one of these had a lumbar spine bone mineral density T score below -2.5, whilst the T score was between -1 and -2.5 in three and greater than -1 in three. Two of these women also had lumbar spine vertebral deformity but lumbar spine radiographs were normal in the remaining five. There were no significant differences in age, height, weight, hormone replacement therapy use or bone mineral density between women with and without thoracic spine fractures. These results demonstrate that vertebral deformities in the thoracic spine occur in a proportion of healthy post-menopausal women in the absence of densitometric or radiographic evidence of osteoporosis in the lumbar spine. Although often asymptomatic, the significance of these fractures lies in the increased risk of further fractures. In the future, morphometric X-ray absorptiometric techniques may prove valuable in the detection of these fractures and avoid the need for conventional radiography.

Developing community networks to deliver HIV prevention interventions.

Outreach has a long history in health and social service programs as an important method for reaching at-risk persons within their communities. One method of "outreach" is based on the recruitment of networks of community members (or "networkers") to deliver HIV prevention messages and materials in the context of their social networks and everyday lives. This paper documents the experiences of the AIDS Community Demonstration Projects in recruiting networkers to deliver HIV prevention interventions to high-risk populations, including injecting drug users not in treatment; female sex partners of injecting drug users; female sex traders; men who have sex with men but do not self-identify as gay; and youth in high-risk situations. The authors interviewed project staff and reviewed project records of the implementation of community networks in five cities. Across cities, the projects successfully recruited persons into one or more community networks to distribute small media materials, condoms, and bleach kits, and encourage risk-reduction behaviors among community members. Networkers' continuing participation was enlisted through a variety of monetary and nonmonetary incentives. While continuous recruitment of networkers was necessary due to attrition, most interventions reported maintaining a core group of networkers. In addition, the projects appeared to serve as a starting point for some networkers to become more active in other community events and issues.