Bending impact on the performance of a flexible Li4Ti5O12-based all-solid-state thin-film battery.

The growing demand of flexible electronic devices is increasing the requirements of their power sources. The effect of bending in thin-film batteries is still not well understood. Here, we successfully developed a high active area flexible all-solid-state battery as a model system that consists of thin-film layers of Li4Ti5O12, LiPON, and Lithium deposited on a novel flexible ceramic substrate. A systematic study on the bending state and performance of the battery is presented. The battery withstands bending radii of at least 14 mm achieving 70% of the theoretical capacity. Here, we reveal that convex bending has a positive effect on battery capacity showing an average increase of 5.5%, whereas concave bending decreases the capacity by 4% in contrast with recent studies. We show that the change in capacity upon bending may well be associated to the Li-ion diffusion kinetic change through the electrode when different external forces are applied. Finally, an encapsulation scheme is presented allowing sufficient bending of the device and operation for at least 500 cycles in air. The results are meant to improve the understanding of the phenomena present in thin-film batteries while undergoing bending rather than showing improvements in battery performance and lifetime.

Correction: Stability of thin film glasses of toluene and ethylbenzene formed by vapor deposition: an in situ nanocalorimetric study.

Correction for 'Stability of thin film glasses of toluene and ethylbenzene formed by vapor deposition: an in situ nanocalorimetric study' by Edgar Leon-Gutierrez et al., Phys. Chem. Chem. Phys., 2010, 12, 14693-14698.

Stability of thin film glasses of toluene and ethylbenzene formed by vapor deposition: an in situ nanocalorimetric study.

Vapor deposited thin films (~100 nm thickness) of toluene and ethylbenzene grown by physical vapor deposition show enhanced stability with respect to samples slowly cooled from the liquid at a rate of 5 K min(-1). The heat capacity is measured in situ immediately after growth from the vapor or after re-freezing from the supercooled liquid at various heating rates using quasi-adiabatic nanocalorimetry. Glasses obtained from the vapor have low enthalpies and large heat capacity overshoots that are shifted to high temperatures. The stability is maximized at growth temperatures in the vicinity of 0.8 T(g) for both molecules, although glasses of ethylbenzene show superior stabilization. Our data is consistent with previous results of larger organic molecules suggesting a generalized behavior on the stability of organic glasses grown from the vapor. In addition, we find that for the small molecules analyzed here, slowing the growth rate below 0.1 nm s(-1) does not result in increased thermodynamic stability.

Nanoscale electrochemical response of lithium-ion cathodes: a combined study using C-AFM and SIMS.

The continuous demand for improved performance in energy storage is driving the evolution of Li-ion battery technology toward emerging battery architectures such as 3D all-solid-state microbatteries (ASB). Being based on solid-state ionic processes in thin films, these new energy storage devices require adequate materials analysis techniques to study ionic and electronic phenomena. This is key to facilitate their commercial introduction. For example, in the case of cathode materials, structural, electrical and chemical information must be probed at the nanoscale and in the same area, to identify the ionic processes occurring inside each individual layer and understand the impact on the entire battery cell. In this work, we pursue this objective by using two well established nanoscale analysis techniques namely conductive atomic force microscopy (C-AFM) and secondary ion mass spectrometry (SIMS). We present a platform to study Li-ion composites with nanometer resolution that allows one to sense a multitude of key characteristics including structural, electrical and chemical information. First, we demonstrate the capability of a biased AFM tip to perform field-induced ionic migration in thin (cathode) films and its diagnosis through the observation of the local resistance change. The latter is ascribed to the internal rearrangement of Li-ions under the effect of a strong and localized electric field. Second, the combination of C-AFM and SIMS is used to correlate electrical conductivity and local chemistry in different cathodes for application in ASB. Finally, a promising starting point towards quantitative electrochemical information starting from C-AFM is indicated.

High Specific Power Dual-Metal-Ion Rechargeable Microbatteries Based on LiMn2O4 and Zinc for Miniaturized Applications.

Miniaturized rechargeable batteries with high specific power are required for substitution of the large sized primary batteries currently prevalent in integrated systems since important implications in dimensions and power are expected in future miniaturized applications. Commercially available secondary microbatteries are based on lithium metal which suffers from several well-known safety and manufacturing issues and low specific power when compared to (super) capacitors. A high specific power and novel dual-metal-ion microbattery based on LiMn2O4, zinc, and an aqueous electrolyte is presented in this work. Specific power densities similar to the ones exhibited by typical electrochemical supercapacitors (3400 W kg-1) while maintaining specific energies in the range of typical Li-ion batteries are measured (∼100 Wh kg-1). Excellent stability with very limited degradation (99.94% capacity retention per cycle) after 300 cycles is also presented. All of these features, together with the intrinsically safe nature of the technology, allow anticipation of this alternative micro power source to have high impact, particularly in the high demand field of newly miniaturized applications.

Ultrafast Dischargeable LiMn2O4 Thin-Film Electrodes with Pseudocapacitive Properties for Microbatteries.

LiMn2O4 (LMO) thin films are deposited on Si-based substrates with Pt current collector via multi-layer pulsed-laser-deposition technique. The LMO thin films feature unique kinetics that yield outstanding electrochemical cycling performance in an aqueous environment. At extremely high current densities of up to 1880 µA cm-2 (≈ 348 C), a reversible capacity of 2.6 µAh cm-2 is reached. Furthermore, the electrochemical cycling remains very stable for over 3500 cycles with a remarkable capacity retention of 99.996% per cycle. We provide evidence of significant nondiffusion-controlled, pseudocapacitive-like storage contribution of the LMO electrode.

Electrical Characterization of Ultrathin RF-Sputtered LiPON Layers for Nanoscale Batteries.

Ultrathin lithium phosphorus oxynitride glass (LiPON) films with thicknesses down to 15 nm, deposited by reactive sputtering in nitrogen plasma, were found to be electronically insulating. Such ultrathin electrolyte layers could lead to high power outputs and increased battery energy densities. The effects of stoichiometry, film thickness, and substrate material on the ionic conductivity were investigated. As the amount of nitrogen in the layers increased, the activation energy of the ionic conductivity decreased from 0.63 to 0.53 eV, leading to a maximum conductivity of 1 × 10(-6) S/cm. No dependence of the ionic conductivity on the film thickness or substrate material could be established. A detailed analysis of the equivalent circuit model used to fit the impedance data is provided. Polarization measurements were performed to determine the electronic leakage in these ultrathin films. A 15-nm LiPON layer on a TiN substrate showed electronically insulating properties with electronic resistivity values around 10(15) Ω·cm. To our knowledge, this is the thinnest RF-sputtered LiPON layer shown to be electronically insulating while retaining good ionic conductivity.

High Cycling Stability and Extreme Rate Performance in Nanoscaled LiMn2O4 Thin Films.

Ultrathin LiMn2O4 electrode layers with average crystal size of ∼15 nm were fabricated by means of radio frequency sputtering. Cycling behavior and rate performance was evaluated by galvanostatic charge and discharge measurements. The thinnest films show the highest volumetric capacity and best cycling stability, retaining the initial capacity over 70 (dis)charging cycles when manganese dissolution is prevented. The increased stability for film thicknesses below 50 nm allows cycling in both the 4 and 3 V potential regions, resulting in a high volumetric capacity of 1.2 Ah/cm3. It is shown that the thinnest films can be charged to 75% of their full capacity within 18 s (200 C), the best rate performance reported for LiMn2O4. This is explained by the short diffusion lengths inherent to thin films and the absence of phase transformation.

Monosodium glutamate neonatal intoxication associated with obesity in adult stage is characterized by chronic inflammation and increased mRNA expression of peroxisome proliferator-activated receptors in mice.

The monosodium glutamate (MSG) neonatal administration in mice provides a model of obesity with impaired glucose tolerance (IGT) and insulin resistance. However, the inflammatory profile of cytokines produced from fat tissue and its relationship to the metabolic dysfunction induced by MSG have not yet been revealed. The aim of this study was to establish the inflammatory profile attributed to MSG by measuring the expression of adipokines in visceral fat and serum of 19-week-old mice as well as the peroxisome proliferator-activated receptors alpha and gamma (PPARα and γ). Some metabolic and biochemical parameters were also quantified. The MSG increased mRNA expression of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNFα), resistin and leptin, but adiponectin did not exhibit any changes. In addition, impaired glucose tolerance, increased levels of insulin, resistin and leptin were observed in serum. Both PPARα and PPARγ were activated in MSG-induced obese mice, which might explain its inflammatory profile. However, liver transaminases were severely depressed, indicating that MSG may also induce liver injury, contributing to inflammation. The MSG neonatal neuro-intoxication in mice may thus provide a model of obesity and inflammation characterized by the dual activation of PPARα and PPARγ, which might offer new insights into the mechanism of inflammatory diabetes in obesity leading to steatohepatitis, as well as a suitable model to study the role of new therapeutic agents to prevent or reduce insulin resistance, the inflammatory state and liver steatosis.

Knowledge about local anesthetics in odontology students.

The purpose of the study was to identify the level of knowledge of local anesthetics frequently used in the surgical clinic by third and fourth year dental students in daily practice. The importance of pharmacology in dental practice in underscored by potential drug toxicity. The study was performed with 244 third and fourth grade career dental students (CDS). Eleven items regarding the knowledge over local anesthetics at the clinic; i.e., the appropriate doses, possible toxic effects and side effects were examined. The reference questionnaire which is in a validation process, is a way to evaluate student knowledge about most drugs used in odontology practice such as: NSAIDs, antibiotics and local anesthetics. The results were found to be unsatisfactory with a high percentage of students failing (less than six of eleven items correct). We conclude that determination of practice knowledge is an essential step in informing the institution about cognitive deficiencies identified in order to plan learning solutions.

Acute toxicity of guaiacol administered subcutaneously in the mouse.

Guaiacol is a compound used as expectorant. In Mexico City, this product is being illegally used for aesthetic treatment with fatal results. The aim of this study is to confirm the lethal toxicity documented in humans. Male Swiss Webster mice (CFW) 30-45g were employed. Dose-response curves to guaiacol were performed by subcutaneous administration (6.25-400 microl/40g). Basal temperature was recorded 30-120 min following administration of guaiacol. Animals were continuously observed for 120 min after guaiacol administration, lethality and toxicity manifestations were recorded. Depending of the dose, high toxicity was observed; sub lethal doses (6.25-12.5 microl/40 g) produced tachycardia and hyperactivity, follow by sedation, hypnosis, high hypothermic effect (loss of 6 degrees C) dyspnea, myoclonus, hematuria, blindness, abdominal distension and in higher doses (25-400 microl/40 g) lethal effect. Necropsy showed hepatic and renal necrosis, pulmonary edema, hemorrhages and bladder clotting. We concluded that guaiacol is an extremely toxic product (toxic rating class 5) whose use should be restricted or banned.

Neonatal monosodium glutamate administration increases aminooxyacetic acid (AOA) susceptibility effects in adult mice.

Neonatal administration of monosodium glutamate (MSG) to mice causes neurotoxicity of the CNS resulting in endocrine, metabolic and behavioral abnormalities. Aminooxyacetic acid (AOAA) is a potent inhibitor of GABA-transaminase and increases GABA levels in the brain. In this work, we studied the effect of neonatal treatment of CFW mice with MSG (2 mg/g sc on the 2nd and 4th days after birth followed by 4 mg/g on days 6, 8 and 10) on AOAA- (100 to 250 mg/kg ip) induced hypothermia, hypnosis and lethality after six months of treatment. The control group was vehicle-treated only. MSG treatment significantly increased susceptibility to the hypothermic, hypnotic and lethal effect of AOAA acutely administered. The increased susceptibility to the depressor effects of AOAA may occur as a consequence of changes in neural excitability, up regulation of GABA-receptors or might be related to pharmacokinetic modifications induced by neonatal treatment with MSG.

Analgesia Preventiva en un modelo experimental de dolor visceral / Pre-emptive analgesia in an experimental model of visceral pain

Objetivo. Evaluar la eficacia de la analgesia preventiva inducida por estimulación eléctrica nerviosa transcutánea (TENS) sobre la respuesta constrictora abdominal (RCA) evocada por Perezona en el ratón. Material y Métodos. Se emplearon 64 ratones macho de la cepa CD-1 dividido en 8 grupos (n=8 cada grupo). El grupo I recibió la perezona 5 mg/kg Intraperitoneal (IP), el grupo II recibió el vehículo de la perezona (aceite de maíz Los grupos IV al VIII se sometieron a diferentes frecuencias de TENS (10,20,40,80 y 160 Hz), durante 30 minutos, posteriormente se les administró perezona 5 mg/kg IP registrando el número de RCA en 20 minutos. Resultados. A los resultados obtenidos se le aplicó la prueba de Kruskal-Wallis siendo estadísticamente significativo los valores de p>0.05, encontrando eficacia antinociceptiva preventiva del TENS en los grupos IV al VII con p<0.05 con respecto a los grupos controles (I y II). El grupo III (vehículo) no registró capacidad para inducir RCA. Conclusiones. Los hallazgos señalan que las frecuencias bajas de TENS (10,20,40 y 80 Hz) son más eficaces para inducir un efecto antinociceptivo en este modelo experimental con relación a las frecuencias altas, (160 Hz) con p>0.05. Se concluye que el TENS es un procedimiento eficaz como analgésico preventivo