Hierarchical Assemblies of Carbon Nanotubes for Ultraflexible Li-Ion Batteries.

The flexible batteries that are needed to power flexible circuits and displays remain challenging, despite considerable progress in the fabrication of such devices. Here, it is shown that flexible batteries can be fabricated using arrays of carbon nanotube microstructures, which decouple stress from the energy-storage material. It is found that this battery architecture imparts exceptional flexibility (radius ≈ 300 μm), high rate (20 A g(-1) ), and excellent cycling stability.Engineering and Physical Sciences Research Council (Grant ID: EP/L025531/1)This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/adma.20160091

Ultrafast carrier dynamics in gold/iron-oxide nanocrystal heterodimers

Colloidal nanocrystal heterodimers composed of a gold domain and an iron oxide domain have been investigated by femtosecond transient absorption spectroscopy. The measured decay times were compared with the ones obtained from samples of "only" gold nanocrystals and iron oxide nanocrystals. Our results indicate that there is no significant charge transfer at the interface between gold and iron oxide in heterodimers

Redox Centers Evolution in Phospho-Olivine Type (LiFe0. 5Mn0. 5 PO4) Nanoplatelets with Uniform Cation Distribution

Accepted Version of the publication: Nano Lett. 2014, 14, 3, 1477–1483. Publication Date: February 24, 2014. https://doi.org/10.1021/nl4046697 © 2014 American Chemical Society. In phospho-olivine type structures with mixed cations (LiM1M2PO4), the octahedral M1 and M2 sites that dictate the degree of intersites order/disorder play a key role in determining their electrochemical redox potentials. In the case of LiFexMn1−xPO4, for example, in micrometer-sized particles synthesized via hydrothermal route, two separate redox centers corresponding to Fe2+/Fe3+ (3.5 V vs Li/Li+) and Mn2+/Mn3+ (4.1 V vs Li/Li+), due to the collective Mn−O−Fe interactions in the olivine lattice, are commonly observed in the electrochemical measurements. These two redox processes are directly reflected as two distinct peak potentials in cyclic voltammetry (CV) and equivalently as two voltage plateaus in their standard charge/discharge characteristics (in Li ion batteries). On the contrary, we observed a single broad peak in CV from LiFe0.5Mn0.5PO4 platelet-shaped (∼10 nm thick) nanocrystals that we are reporting in this work. Structural and compositional analysis showed that in these nanoplatelets the cations (Fe, Mn) are rather homogeneously distributed in the lattice, which is apparently the reason for a synergetic effect on the redox potentials, in contrast to LiFe0.5Mn0.5PO4 samples obtained via hydrothermal routes. After a typical carbon-coating process in a reducing atmosphere (Ar/H2), these LiFe0.5Mn0.5PO4 nanoplatelets undergo a rearrangement of their cations into Mn-rich and Fe-rich domains. Only after such cation rearrangement (via segregation) in the nanocrystals, the redox processes evolved at two distinct potentials, corresponding to the standard Fe2+/Fe3+ and Mn2+/Mn3+ redox centers. Our experimental findings provide new insight into mixed-cation olivine structures in which the degree of cations mixing in the olivine lattice directly influences the redox potentials, which in turn determine their charge/discharge characteristics

Colloidal Cu 2-x(S ySe 1-y) alloy nanocrystals with controllable crystal phase: Synthesis, plasmonic properties, cation exchange and electrochemical lithiation

We report synthetic routes to both cubic and hexagonal phase Cu 2-x(S ySe 1-y) alloy nanocrystals exhibiting a well-defined near-infrared valence band plasmon resonance, the spectral position of which is dependent mainly on x, i.e. on Cu stoichiometry, and to a lesser extent on the crystal phase of the NCs. For cubic Cu 2-x(S ySe 1-y) nanocrystals y could be varied in the 0.4-0.6 range, while for hexagonal nanocrystals y could be varied in the 0.3-0.7 range. Furthermore, the Cu 2-x(S ySe 1-y) nanocrystals could be transformed into the corresponding Cd-based alloy nanocrystals with comparable S ySe 1-y stoichiometry, by cation exchange. The crystal phase of the resulting Cd(S ySe 1-y) nanocrystals was either cubic or hexagonal, depending on the phase of the starting nanocrystals. One sample of cubic Cu 2-x(S ySe 1-y) nanocrystals, with S 0.5Se 0.5 chalcogenide stoichiometry, was then evaluated as the anode material in Li-ion batteries. The nanocrystals were capable of undergoing lithiation/delithiation via a displacement/conversion reaction (Cu to Li and vice versa) in a partially reversible manner. © 2012 The Royal Society of Chemistry

Adherence to Artesunate-Amodiaquine Therapy for Uncomplicated Malaria in Rural Ghana: A Randomised Trial of Supervised versus Unsupervised Drug Administration

Introduction. To enhance effective treatment, african nations including Ghana changed its malaria treatment policy from monotherapy to combination treatment with artesunate-amodiaquine (AS+AQ). The major challenge to its use in loose form is adherence. Objective. The objectives of this study were to investigate adherence and treatment outcome among patients treated with AS+AQ combination therapy for acute uncomplicated malaria. Methodology. The study was conducted in two rural districts located in the middle belt of Ghana using quantitative methods. Patients diagnosed with acute uncomplicated malaria as per the Ghana Ministry of Health malaria case definitions were randomly allocated to one of two groups. All patients in both groups were educated about the dose regimen of AS+AQ therapy and the need for adherence. Treatment with AS+AQ was supervised in one group while the other group was not supervised. Adherence was assessed by direct observation of the blister package of AS+AQ left on day 2. Results. 401 participants were randomized into the supervised (211) and unsupervised (190) groups. Compliance in both supervised (95.7%) and unsupervised (92.6%) groups were similar (P = .18). The commonest side-effects reported on day 2 among both groups were headaches, and body weakness. Parasite clearance by day 28 was >95% in both groups. Discussion/Conclusions. Administration of AS-AQ in both groups resulted in high levels of adherence to treatment regimen among adolescent and adult population in central Ghana. It appears that high level of adherence to AS-AQ is achievable through a rigorous education programme during routine clinic visits

Photo-Rechargeable Organo-Halide Perovskite Batteries.

Emerging autonomous electronic devices require increasingly compact energy generation and storage solutions. Merging these two functionalities in a single device would significantly increase their volumetric performance, however this is challenging due to material and manufacturing incompatibilities between energy harvesting and storage materials. Here we demonstrate that organic-inorganic hybrid perovskites can both generate and store energy in a rechargeable device termed a photobattery. This photobattery relies on highly photoactive two-dimensional lead halide perovskites to simultaneously achieve photocharging and Li-ion storage. Integrating these functionalities provides simple autonomous power solutions while retaining capacities of up to 100 mAh/g and efficiencies similar to electrodes using a mixture of batteries and solar materials

A cast-mold approach to iron oxide and Pt/iron oxide nanocontainers and nanoparticles with a reactive concave surface.

We report the synthesis of various iron oxide nanocontainers and Pt−iron oxide nanoparticles based on a cast-mold approach, starting from nanoparticles having a metal core (either Au or AuPt) and an iron oxide shell. Upon annealing, the particles evolve to asymmetric core−shells and then to heterodimers. If iodine is used to leach Au out of these structures, asymmetric core−shells evolve into "nanocontainers", that is, iron oxide nanoparticles enclosing a cavity accessible through nanometer-sized pores, while heterodimers evolve into particles with a concave region. When starting from a metal domain made of AuPt, selective leaching of the Au atoms yields the same iron oxide nanoparticle morphologies but now encasing Pt domains (in their concave region or in their cavity). We found that the concave nanoparticles are capable of destabilizing Au nanocrystals of sizes matching that of the concave region. In addition, for the nanocontainers, we propose two different applications: (i) we demonstrate loading of ..

Multiple functionalization of fluorescent nanoparticles for specific biolabeling and drug delivery of dopamine

The development of fluorescent biolabels for specific targeting and controlled drug release is of paramount importance in biological applications due to their potential in the generation of novel tools for simultaneous diagnosis and treatment of diseases. Dopamine is a neurotransmitter involved in several neurological diseases, such as Parkinson's disease and attention deficit hyperactivity disorder (ADHD), and the controlled delivery of its agonists already proved to have beneficial effects both in vitro and in vivo. Here, we report the synthesis and multiple functionalization of highly fluorescent CdSe/CdS quantum rods for specific biolabeling and controlled drug release. After being transferred into aqueous media, the nanocrystals were made highly biocompatible through PEG conjugation and covered by a carbohydrate shell, which allowed specific GLUT-1 recognition. Controlled attachment of dopamine through an ester bond also allowed hydrolysis by esterases, yielding a smart nanotool for specific biolabeling and controlled drug release

Non-malaria fevers in a high malaria endemic area of Ghana.

BACKGROUND: The importance of fevers not due to malaria [non-malaria fevers, NMFs] in children in sub-Saharan Africa is increasingly being recognised. We have investigated the influence of exposure-related factors and placental malaria on the risk of non-malaria fevers among children in Kintampo, an area of Ghana with high malaria transmission. METHODS: Between 2008 and 2011, a cohort of 1855 newborns was enrolled and followed for at least 12 months. Episodes of illness were detected by passive case detection. The primary analysis covered the period from birth up to 12 months of age, with an exploratory analysis of a sub-group of children followed for up to 24 months. RESULTS: The incidence of all episodes of NMF in the first year of life (first and subsequent) was 1.60 per child-year (95 % CI 1.54, 1.66). The incidence of NMF was higher among infants with low birth weight [adjusted hazard ratio (aHR) 1.22 (95 % CI 1.04-1.42) p = 0.012], infants from households of poor socio-economic status [aHR 1.22 (95 % CI 1.02-1.46) p = 0.027] and infants living furthest from a health facility [aHR 1.20 (95 % CI 1.01-1.43) p = 0.037]. The incidence of all episodes of NMF was similar among infants born to mothers with or without placental malaria [aHR 0.97 (0.87, 1.08; p = 0.584)]. CONCLUSION: The incidence of NMF in infancy is high in the study area. The incidence of NMF is associated with low birth weight and poor socioeconomic status but not with placental malaria