Interfacial Chemistry Effects in the Electrochemical Performance of Silicon Electrodes under Lithium-Ion Battery Conditions.

Understanding the solid electrolyte interphase (SEI) formation and (de)lithiation phenomena at silicon (Si) electrodes is key to improving the performance and lifetime of Si-based lithium-ion batteries. However, these processes remain somewhat elusive, and, in particular, the role of Si surface termination merits further consideration. Here, scanning electrochemical cell microscopy (SECCM) is used in a glovebox, followed by secondary ion mass spectrometry (SIMS) at identical locations to study the local electrochemical behavior and associated SEI formation, comparing Si (100) with a native oxide layer (SiOx /Si) and etched with hydrofluoric acid (HF-Si). HF-Si shows greater spatial electrochemical heterogeneity and inferior lithiation reversibility than SiOx /Si. This is attributed to a weakly passivating SEI and irreversible lithium trapping at the Si surface. Combinatorial screening of charge/discharge cycling by SECCM with co-located SIMS reveals SEI chemistry as a function of depth. While the SEI thickness is relatively independent of the cycle number, the chemistry - particularly in the intermediate layers - depends on the number of cycles, revealing the SEI to be dynamic during cycling. This work serves as a foundation for the use of correlative SECCM/SIMS as a powerful approach to gain fundamental insights on complex battery processes at the nano- and microscales.

Low-noise-figure and high-purity 10 vortex modes amplifier based on configurable pump modes.

We have explored an orbital angular momentum (OAM) amplifier of 10 vortex modes under different-order OAM pump modes, i.e. OAM0, OAM1, and OAM2. The all-fiber amplification system consists of an active few-mode erbium-doped fiber (FM-EDF), a mode selective pump (MSP), and a mode selective signal (MSS). These mode selective components are based on fused-taper mode selective couplers (MSC) under different wavelengths fabricated by a passive ring-core fiber (RCF). Under different-order mode pumps, the OAM amplifier experimentally exhibits mode gains (MGs) above 15 dB for 10 vortex modes with the mode purities only 89%, essentially in line with the simulation results. Especially when the signal-mode profiles are better matched to the pump-mode profiles, i.e. the OAM pumps with the same order as signals, the obtained MGs are all over 20.2 dB and the amplified OAM mode purity is up to 97%; the acquired noise figures (NFs) are <4.9 dB and even the minimum NF is 3.2 dB. The results reveal that the OAM amplifier shows low-NF and high-purity characteristics under configurable pump modes in C-band. The amplified high-order OAM mode could be promising for uses in the long-distance mode division multiplexing (MDM) and in mitigation of the upcoming capacity crunch in optical fiber communication.

Combined Stabilizing of the Solid-Electrolyte Interphase with Suppression of Graphite Exfoliation via Additive-Solvent Optimization in Li-Ion Batteries.

Propylene carbonate (PC) is a promising solvent for extending the operating temperature range for lithium-ion batteries (LIBs) because of its high dielectric constant and wide temperature range stability. However, PC can cause graphite exfoliation through cointercalation, leading to electrolyte decomposition and subsequent irreversible capacity loss. This work reports the formulation of a ternary electrolyte with the introduction of an inorganic salt additive, potassium hexafluorophosphate (KPF6), to address the aforementioned concerns. We demonstrate the cumulative effect of solvent and additive on delivering multiple performance benefits and safety of the battery. The faster diffusion rate of K + solvation shell decreases the rate of PC decomposition, thereby reducing its cointercalation. Additionally, the optimum concentration of KPF6, i.e., 0.1 M constructs a robust and insoluble LiF-rich electrode/electrolyte interphase, further suppressing graphite exfoliation and Li dendrite formation. The stable cyclability is achieved by enhanced Li + transportation through the LiF-rich interphase, enabling an exfoliation-free and dendrite-free graphite anode in the ternary electrolyte.

Periconnection: A novel macroecological effect in snow cover phenology modulating ecosystem productivity over upper Northern Hemisphere.

Snow cover plays an important role in maintaining ecosystems. However, knowledge on how snow cover phenology (SP) modulates ecosystem productivity (EP), especially for the lower- and higher-productivity ecosystems, is limited yet. The situation becomes more embarrassed when asking a more in-depth question as to the macroecological pattern of SP modulating EP - does this process act with the neighborhood effect common in ecology or any other? To answer this question, we proposed a new concept of "periconnection", by following the way of defining "teleconnection" but also exploring the potential effect from the surrounding sites. In the case study of two published data of plant dynamics (1999-2013) and SP (2001-2014), we made a series of new findings as follows. Over upper Northern Hemisphere, the lower- and higher-productivity ecosystems presented weaker trends of productivity increasing than the entire ecosystems did. But for the ecosystems of all these three types, their productivity was all more sensitive to the snow-onset than -end SP. Further, the interannual variations of their productivity was all more modulated by the SP around - the neighborhood effect, in principle, was detected but also with other novel traits. Such modulations occurred more to north in North America while more to south in North Eurasia - termed directional effect. The first two inferences added the common knowledge of SP modulating EP, while the in-depth question was solved with the last two coherent effects, which compose a new macroecological beyond-neighborhood effect - periconnection. As a creative theoretical term and its principle framework in macroecology, this basic concept is of referencing implication on extensively advancing various sphere-interaction fields at other scales.

Controlling Li Dendritic Growth in Graphite Anodes by Potassium Electrolyte Additives for Li-Ion Batteries.

Fast charging promotes Li dendrite formation and its growth on graphite anodes, which affects cell performance in Li-ion batteries (LIBs). This work reports the formation of a robust SEI layer by introducing a KPF6 inorganic additive into the electrolyte. An optimal concentration of 0.001 M KPF6 effectively inhibits the growth of Li dendrites at 2C charging rates, compared with a commercial electrolyte. Electrolytes containing a KPF6 additive are shown here to deliver dual effects to mitigate the growth of dendrites. A thin LiF-rich SEI layer is formed on graphite, which blocks the electron leakage pathways. Additionally, K+ resides at defect sites (such as particle boundaries) due to its faster diffusion rate and blocks the incoming Li+ and restricts the growth of Li dendrites. The electrolyte with optimum concentration of KPF6, i.e., 0.001 M, effectively directs Li+ transport through the thin, durable, and low resistance LiF-rich SEI layer. This has implications for fast charging through optimization of the electrode/electrolyte interphase by controlling additive concentrations.

Adiabatic versus non-adiabatic electron transfer at 2D electrode materials.

2D electrode materials are often deployed on conductive supports for electrochemistry and there is a great need to understand fundamental electrochemical processes in this electrode configuration. Here, an integrated experimental-theoretical approach is used to resolve the key electronic interactions in outer-sphere electron transfer (OS-ET), a cornerstone elementary electrochemical reaction, at graphene as-grown on a copper electrode. Using scanning electrochemical cell microscopy, and co-located structural microscopy, the classical hexaamineruthenium (III/II) couple shows the ET kinetics trend: monolayer > bilayer > multilayer graphene. This trend is rationalized quantitatively through the development of rate theory, using the Schmickler-Newns-Anderson model Hamiltonian for ET, with the explicit incorporation of electrostatic interactions in the double layer, and parameterized using constant potential density functional theory calculations. The ET mechanism is predominantly adiabatic; the addition of subsequent graphene layers increases the contact potential, producing an increase in the effective barrier to ET at the electrode/electrolyte interface.

Evaluation of TELEDERM for dermatological services in rural and remote areas.

OBJECTIVE: This paper describes the Web-based decision support system (TELEDERM) that provides medical services to rural and remote general practitioners (GPs), and presents qualitative results on the usefulness and usability of the system obtained from trials in the GoldFields, Western Australia. METHODS: Diagnostic methods and other functions were developed to assist medical practitioners, who may not be familiar with aspects of decision support systems, to diagnose patients with dermatological problems. GPs in rural and remote areas took part in a trial to assess the usefulness of TELEDERM in clinical situations. In evaluating and assessing a number of the system's characteristics, questionnaires, seminars and interviews were used. RESULTS AND CONCLUSIONS: Feedback concerning the usefulness of TELEDERM shows that 67% of the GPs found the system useful or very useful, and 25% found the system somewhat useful. In terms of its usability, 83% found the system easy to use. The responses concerning the user interface and interactivity of TELEDERM are encouraging as 92% of the GPs found the text easy to read, 84% were happy with the appearance of the interface, and 84% found the system easy to navigate. 89% indicated that they are likely to use the system again. An issue with such systems is the reluctance of GPs to use them, even given that the development was quite sensitive to the needs of the GPs and the consultants, e.g. by streamlining the query process and emphasising that the system is a support tool and not a replacement.

Dynamic knowledge validation and verification for CBR teledermatology system.

OBJECTIVE: Case-based reasoning has been of great importance in the development of many decision support applications. However, relatively little effort has gone into investigating how new knowledge can be validated. Knowledge validation is important in dealing with imperfect data collected over time, because inconsistencies in data do occur and adversely affect the performance of a diagnostic system. METHODS: This paper consists of two parts. First, it describes methods that enable the domain expert, who may not be familiar with machine learning, to interactively validate knowledge base of a Web-based teledermatology system. The validation techniques involve decision tree classification and formal concept analysis. Second, it describes techniques to discover unusual relationships hidden in the dataset for building and updating a comprehensive knowledge base, because the diagnostic performance of the system is highly dependent on the content thereof. Therefore, in order to classify different kinds of diseases, it is desirable to have a knowledge base that covers common as well as uncommon diagnoses. RESULTS AND CONCLUSION: Evaluation results show that the knowledge validation techniques are effective in keeping the knowledge base consistent, and that the query refinement techniques are useful in improving the comprehensiveness of the case base.

Simultaneous Topography and Reaction Flux Mapping at and around Electrocatalytic Nanoparticles.

The characterization of electrocatalytic reactions at individual nanoparticles (NPs) is presently of considerable interest but very challenging. Herein, we demonstrate how simple-to-fabricate nanopipette probes with diameters of approximately 30 nm can be deployed in a scanning ion conductance microscopy (SICM) platform to simultaneously visualize electrochemical reactivity and topography with high spatial resolution at electrochemical interfaces. By employing a self-referencing hopping mode protocol, whereby the probe is brought from bulk solution to the near-surface at each pixel, and with potential-time control applied at the substrate, current measurements at the nanopipette can be made with high precision and resolution (30 nm resolution, 2600 pixels µm-2, <0.3 s pixel-1) to reveal a wealth of information on the substrate physicochemical properties. This methodology has been applied to image the electrocatalytic oxidation of borohydride at ensembles of AuNPs on a carbon fiber support in alkaline media, whereby the depletion of hydroxide ions and release of water during the reaction results in a detectable change in the ionic composition around the NPs. Through the use of finite element method simulations, these observations are validated and analyzed to reveal important information on heterogeneities in ion flux between the top of a NP and the gap at the NP-support contact, diffusional overlap and competition for reactant between neighboring NPs, and differences in NP activity. These studies highlight key issues that influence the behavior of NP assemblies at the single NP level and provide a platform for the use of SICM as an important tool for electrocatalysis studies.

Delivery of large molecular protein using flat and short microneedles prepared using focused ion beam (FIB) as a skin ablation tool.

Many studies have been reported in the literature on the effects of various geometries and lengths of microneedles (MNs) on transdermal drug delivery using a variety of drug molecules. In particular, sharp-tipped MNs have been used to disrupt the top layer of the skin, namely, stratum corneum (SC). It has also been shown that short- and flat-tipped MNs can pierce the SC and they have the potential to increase drug permeability. However, there is little work that explores MNs as a skin ablative tool with a view to increasing skin permeability. To address this point, well-defined small patterns (size of individual pattern 10-20 µm) on the tip of flat MN (tip radius of individual MN ∼250 µm) were created and their effects evaluated on the permeability of bovine serum albumin (BSA), which is chosen as a model drug of high molecular weight. The patterns on the tip of flat MN act as rough surfaces (e.g. like sand paper) which when applied on the surface of the skin ablate the SC layer. Focused ion beam (FIB) has been used as the fabrication technique for the MNs. The permeability data are then compared with the other data for flat- and sharp-tipped MN. The permeability data from passive diffusion experiments are used as the reference case. The exact number of MNs or patterns in the flat and patterned MN patches is not considered as important as they have not been designed to pierce the skin. However, this is an important consideration in the case of sharp MNs as they pierce and create cavities in the skin. It is found that the delivery of BSA with the fabricated flat and patterned MNs gave similar but somewhat lower drug permeation profile in comparison to the sharp MNs. Passive diffusion showed no permeation, as would be expected due to the large size of the chosen molecule.

Microbial contamination on beef and sheep carcases in South Australia.

A total of 523 chilled beef and lamb carcases were sampled from four abattoirs and 13 very small plants (VSPs) in South Australia during March 2002 in order to develop a microbiological profile of meat produced for domestic consumption within the State. Aerobic viable counts (AVCs) and Escherichia coli counts were obtained from samples taken by sponge-sampling the muscle-adipose tissue at sites designated for each species in the Microbiological Guidelines to the Australian Standard for Hygienic Production of Meat for Human Consumption (identical with those of the USA Pathogen Reduction: hazard analysis and critical control point (HACCP) systems: final rule). On beef carcases (n=159) mean log AVC/cm(2) was 1.82 and E. coli was detected on 18.8% of carcases (area sampled 200 cm(2)) for which the mean log of the positives was -0.34; for lamb carcases, on which 75 cm(2) was sampled (n=364), corresponding values were 2.59, 36.2% and log(10) 0.27, respectively. There was little difference in mean log AVC/cm(2) of carcases produced at abattoirs and VSPs, 1.72 versus 1.81, respectively, for beef, and 2.80 versus 2.44, respectively, for sheep. Prevalence of E. coli was lower at VSPs, however, with abattoirs having 28.4% for beef and 61.5% for sheep, compared with corresponding values of 4.7% and 18.5% at VSPs. In VSPs, the range of mean log AVC/cm(2) was 0.47-3.16 for beef and 1.63-3.65 for sheep carcases, data which will allow the Controlling Authority to assist plants to improve performance of slaughter and dressing techniques. The present survey is part of an assessment by the State meat authority of the effectiveness of co-regulation of meat hygiene between government and industry.

Web-based geo-visualisation of spatial information to support evidence-based health policy: a case study of the development process of HealthTracks.

Place is of critical importance to health as it can reveal patterns of disease spread and clustering, associations with risk factors, and areas with greatest need for, or least access to healthcare services and promotion activities. Furthermore, in order to get a good understanding of the health status and needs of a particular area a broad range of data are required which can often be difficult and time consuming to obtain and collate. This process has been expedited by bringing together multiple data sources and making them available in an online geo-visualisation, HealthTracks, which consists of a mapping and reporting component. The overall aim of the HealthTracks project is to make spatial health information more accessible to policymakers, analysts, planners and program managers to inform decision-making across the Department of Health Western Australia. Preliminary mapping and reporting applications that have been utilised to inform service planning, increased awareness of the utility of spatial information and improved efficiency in data access were developed. The future for HealthTracks involves expanding the range of data available and developing new analytical capabilities in order to work towards providing external agencies, researchers and eventually the general public access to rich local area spatial data.