Highly transparent sustainable biogel electrolyte based on cellulose acetate for application in electrochemical devices.

In this study, an easy and low-cost production method for a cellulose acetate-based gel polymer containing lithium perchlorate and propylene carbonate is described, as well as the investigation of its properties for potential use as an electrolyte in electrochemical devices. Cellulose acetate, a biopolymer derived from natural matrix, is colourless and transparent, as confirmed by the UV-Vis spectroscopy, with 85 % transparency in visible spectrum. The gels were prepared and tested at different concentrations and proportions to optimise their properties. Thermogravimetry, XRD, and FTIR analyses revealed crucial characteristics, including a substantial 90 % mass loss between 150 and 250 °C, a semi-crystalline nature with complete salt dissociation within the polymer matrix, and a decrease in intensity at 1780 cm-1 with increasing Li+ ion concentration, suggesting an improvement in ionic conduction capacity. In terms of electrochemical performance, the gel containing 10 % by mass of cellulose acetate and 1.4 M of LiClO4 emerged as the most promising. It exhibited a conductivity of 2.3 × 10-4 S.cm-1 at 25 °C and 3.0 × 10-4 S.cm-1 at 80 °C. Additionally, it demonstrated an ideal shape of cyclic voltammetry curves and stability after 400 cycles, establishing its suitability as an electrolyte in electrochemical devices.

Selective suppression of {112} anatase facets by fluorination for enhanced TiO2 particle size and phase stability at elevated temperatures.

Generally, anatase is the most desirable TiO2 polymorphic phase for photovoltaic and photocatalytic applications due to its higher photoconductivity and lower recombination rates compared to the rutile phase. However, in applications where temperatures above 500 °C are required, growing pure anatase phase nanoparticles is still a challenge, as above this temperature TiO2 crystallite sizes are larger than 35 nm which thermodynamically favors the growth of rutile crystallites. In this work, we show strong evidence, for the first time, that achieving a specific fraction (50%) of the {112} facets on the TiO2 surface is the key limiting step for anatase-to-rutile phase transition, rather than the crystallite size. By using a fluorinated ionic liquid (IL) we have obtained pure anatase phase crystallites at temperatures up to 800 °C, even after the crystallites have grown beyond their thermodynamic size limit of ca. 35 nm. While fluorination by the IL did not affect {001} growth, it stabilized the pure anatase TiO2 by suppressing the formation of {112} facets on anatase particles. By suppressing the {112} facets, using specific concentrations of fluorinated ionic liquid in the TiO2 synthesis, we controlled the anatase-to-rutile phase transition over a wide range of temperatures. This information shall help synthetic researchers to determine the appropriate material conditions for specific applications.

Peering into the Formation of Template-Free Hierarchical Flowerlike Nanostructures of SrTiO3.

The development of efficient advanced functional materials is highly dependent on properties such as morphology, crystallinity, and surface functionality. In this work, hierarchical flowerlike nanostructures of SrTiO3 have been synthesized by a simple template-free solvothermal method involving poly(vinylpyrrolidone) (PVP). Molecular dynamics simulations supported by structural characterization have shown that PVP preferentially adsorbs on {110} facets, thereby promoting the {100} facet growth. This interaction results in the formation of hierarchical flowerlike nanostructures with assembled nanosheets. The petal morphology is strongly dependent on the presence of PVP, and the piling up of nanosheets, leading to nanocubes, is observed when PVP is removed at high temperatures. This work contributes to a better understanding of how to control the morphological properties of SrTiO3, which is fundamental to the synthesis of perovskite-type materials with tailored properties.

Imprinted Naked Pt Nanoparticles on N-Doped Carbon Supports: A Synergistic Effect between Catalyst and Support.

A synergistic effect resulting from the interaction of small (2.4-3.1 nm) naked Pt nanoparticles (NPs) imprinted on N-doped carbon supports is evidenced by structural, electronic and electrochemical characterization. The size and distribution of the sputtered Pt NPs are found to be related to the nature of the support because Pt NPs are preferentially located at Ngraphitic sites. In addition, Rutherford backscattering shows that a deeper penetration of the Pt NPs is obtained in the N-doped carbon support with larger pore diameters. The ligand effect of the N-doped carbon supports is found to occur by electron donation from Npyrrolic and Ngraphitic sites to the Pt NPs and the electron acceptor behavior of the C=Npyridinic sites. The carbon matrix acquires a basic characteristic (electron-richer, metallic behavior) capable of interacting with metallic NPs akin to a bimetallic-like system. The imprinted Pt NPs are active catalysts for oxidation, although displaying poor catalytic activity for reduction reactions. The catalyst N-doped carbon supports play an important role in the overall catalytic process, rather than only acting as a simple active phase carrier.

Role of the spinal TrkB-NMDA receptor link in the BDNF-induced long-lasting mechanical hyperalgesia in the rat: A behavioural study.

BACKGROUND: Intrathecal/intracisternal BDNF in rodents produces long-lasting hyperalgesia/allodynia, which implies BDNF plays a role in the establishment and maintenance of central sensitization. Both self-regeneration of endogenous BDNF and neuroplastic modifications of spinal NMDA receptors downstream TrkB signalling could be involved in such enduring hyperalgesia. We investigated to what extent BDNF by itself could participate in the generation and maintenance of mechanical hyperalgesia using pharmacological tools. METHODS: We studied sensitivity of mechanical hyperalgesia induced by a single intrathecal (i.t.) injection of BDNF (3 ng/10 µL i.t.) administered at time zero, for: (1) chronic NMDA receptor inhibition with subcutaneously implanted 7-day delivery osmotic pumps loaded with ketamine; (2) TrkB receptor inhibition with intraperitoneal (i.p.) cyclotraxine-B; and (3) chronic glial inhibition with repeated propentofylline i.t. injections. Nociceptive threshold to paw pressure, tested on days -3, 0, 3, 7, 10 and 14, was used as the index of central sensitization. Locomotor patterns and food and water consumption were assessed with LABORAS. RESULTS: Chronic ketamine prevented the mechanical hyperalgesia induced by BDNF, without affecting locomotion and food and water consumption. After pump depletion, a late hyperalgesic response to paw pressure stimulation emerged, which can be lastingly antagonized by cyclotraxine-B. Chronic propentofylline treatment irreversibly suppressed BDNF-induced hyperalgesia. CONCLUSION: Activation of NMDA receptors downstream to TrkB signalling is essential for behavioural expression of the mechanical hyperalgesia induced by intrathecal BDNF. However, maintenance of the hyperalgesia depends mainly from self-regenerating glial BDNF rather than from a NMDA receptor-dependent form of neuroplasticity. SIGNIFICANCE: Intrathecal BDNF induces long-lasting central sensitization via a glial-likely BDNF self-regenerating mechanism, whose behavioural expression depends on downstream activation of NMDA receptors. This knowledge suggests that TrkB antagonists could represent an interesting lead for the development of novel therapeutic strategies for some chronic pain conditions.

Pristine Ta3 N5 Nanotubes: Trap-Driven High External Biasing Perspective in Semiconductor/Electrolyte Interfaces.

Ta3 N5 is a promising photoelectrode for solar hydrogen production; however, to date pristine Ta3 N5 electrodes without loading co-catalysts have presented limited photoelectrochemical (PEC) performance. In particular, large external biasing has been required to run water oxidation, the origin of which is investigated herein. Ta3 N5 nanotubes (NTs) prepared by nitridation were characterized by a wide range of techniques. The bandgap was confirmed by a novel PEC technique. Nondestructive synchrotron-excited XPS has shown the presence of reduced Ta species deeper in the Ta3 N5 surface. Lower photocurrent and transient spikes that were intense at lower applied biasing were observed under water oxidation; however, spikes were inhibited in the presence of a sacrificial agent and photocurrent was improved even at low biasing. It was observed for the first time that the lower PEC performance under water oxidation can be attributed to the presence of interband trapping states associated with pristine Ta3 N5 NTs/electrolyte junction. These states correspond to the structural defects in Ta3 N5 , devastate PEC performance, and present the necessity to apply higher biasing. The key to circumvent them is to use a sacrificial agent in the electrolyte or to load a suitable co-catalyst to avoid hole accumulation under water oxidation, thereby improving the phootocurrent. The findings on the interband states could also provide guidance for the investigation of PEC properties of new types of semiconducting devices.

Structural, optical and photoelectrochemical characterizations of monoclinic Ta3N5 thin films.

Monoclinic Ta3N5 thin films were synthesized by thermal nitridation of amorphous Ta2O5 films directly sputtered by radio frequency magnetron sputtering. The samples were studied by high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis-NIR spectrophotometry, rietveld refinements, spectroscopic ellipsometry and electrochemical techniques. The surface composition of Ta3N5 thin film was found to be different than the underlying film, affecting the optical properties of the material. Rietveld refinement has confirmed that the nitridation process results in Schottky and oxygen substitutional defects within the crystalline structure of monoclinic Ta3N5 thin film. The optical constants of the film were obtained by spectroscopic ellipsometry within a spectral range of 4.60-0.54 eV, i.e. 270-2300 nm. The suitable parameterization was found to consist of three Tauc-Lorentz and one Lorentz oscillators. The conduction band, valence band and the flat band positions were determined by photoelectrochemical techniques, presenting a strong dependence on pH of the eletrolyte. Improved photocurrent was obtained in alkaline conditions and attributed to the shorter depletion region width measured by Mott-Schottky and the lower recombination life time measured by open circuit potential decay analyses.

TiO2 nanotubes sensitized with CdSe via RF magnetron sputtering for photoelectrochemical applications under visible light irradiation.

Highly ordered TiO2 NT arrays were easily decorated with CdSe via RF magnetron sputtering. After deposition thermal annealing at different temperatures was performed to obtain an improved TiO2/CdSe interface. The heterostructures were characterized by RBS, SEM, XRD, HRTEM, UV-Vis, EIS, IPCE and current versus voltage curves. The sensitized semiconducting electrodes display an enhanced photocurrent density of ca. 2 mA cm(-2) at 0.6 V (vs. Ag/AgCl) under visible light (λ > 400 nm). The sensitized photoelectrodes displayed 3 and 535-fold enhanced photocurrent when compared to bare TiO2 NTs under 1 sun and under visible light illumination, respectively. IES results confirmed the improved charge transfer across the TiO2/CdSe/electrolyte interface after annealing at 400 °C. Incident photon-to-electron conversion efficiency measurements confirmed the efficient sensitization by allowing photoresponse in the visible range.

Probing the functionalization of gold surfaces and protein adsorption by PM-IRRAS.

The control of morphology and coating of metal surfaces is essential for a number of organic electronic devices including photovoltaic cells and sensors. In this study, we monitor the functionalization of gold surfaces with 11-mercaptoundecanoic acid (MUA, HS(CH(2) )(10) CO(2) H) and cysteamine, aiming at passivating the surfaces for application in surface plasmon resonance (SPR) biosensors. Using polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), cyclic voltammetry, atomic force microscopy and quartz crystal microbalance, we observed a time-dependent organization process of the adsorbed MUA monolayer with alkyl chains perpendicular to the gold surface. Such optimized condition for surface passivation was obtained with a systematic search for experimental parameters leading to the lowest electrochemical signal of the functionalized gold electrode. The ability to build supramolecular architectures was also confirmed by detecting with PM-IRRAS the adsorption of streptavidin on the MUA-functionalized gold. As the approaches used for surface functionalization and its verification with PM-IRRAS are generic, one may now envisage monitoring the fabrication of tailored electrodes for a variety of applications.

Attomolar protein detection using in-hole surface plasmon resonance.

An in-hole nanohole surface plasmon resonance sensing scheme is demonstrated. Arrays of periodic nanoholes milled through thin layers of SiO(x) and gold were used to detect the binding of organic and biological molecules inside the nanoholes, while blocking the gold surfaces outside the holes. This new approach is more efficient than the previous nanohole array method, where the response was related to binding events taking place inside of the holes and on the top gold surface. The improved sensitivity to binding events and lower detection limit are related to resonant surface plasmon enhanced transmission through the arrays of nanoholes. The sensitivity was found to be 650 nm/RIU and the detection of three attomoles of proteins was estimated from this scheme.

Liver transplantation: experience with our first 100 cases.

OBJECTIVES: Our goal was to evaluate the results of the first 100 liver transplants performed in our institution. METHODS: We retrospectively analyzed the first 100 liver transplants undertaken in adults from November 2001 to August 2005. RESULTS: The mean age of the recipients was 50 years (20 to 69) and 73% were men. The mean waiting time was 35 days. The mean age of the donors was 60 years (15 to 87), and 60% were men. One-year patient and graft survival rates were 93% and 90%, respectively. Three-year patient and graft survival rates were 85% and 82%, respectively. The need for retransplantation was 3%. Surgical complications included hepatic artery stenoses, 2%; hepatic artery thromboses, 2%; biliary leaks, 6%; and biliary stenoses, 14%. CONCLUSIONS: These results are no different from the overall results for liver transplantation in Spain during the same period.

Early clinical and surgical results of biliopancreatic diversion.

BACKGROUND: Scopinaro biliopancreatic diversion (BPD) for morbid obesity results in significant longterm weight loss and reduction or resolution of obesity-associated co-morbidities. The aim of our work was to describe the early results after BPD. METHODS: 59 morbidly obese patients (BMI >40) underwent open BPD from December 2001 to December 2004. We analyzed a consecutive series of 19 patients who have been followed >4 months. We present the data of basal and early visits (2 and 4 months). RESULTS: Initial excess weight percent loss (IEW%L) was 5.2% at 2 months and 13.7% at 4 months. Glycemia, cholesterol, triglyceride levels and blood pressure improved at each visit. All parameters have significant differences from the basal values. 3 patients had sleep apnea syndrome, and overnight CPAP was able to cease in 2 patients by 4 months. 6 patients (31.5%) had albumin <2.5 g/dl, without clinical findings of malnutrition. Total calorie (857+/-79.8 cal/day) and protein (59.8+/-23 g/day) intakes at 4 months were low, with a low intake of multivitamins and oligoelements from food. There was no mortality in this series. Early postoperative morbidity was incisional hernia (21.1%), anastomotic leak (5.2%), wound infection (15.7%), intra-abdominal infection (5.2%), and intestinal obstruction (5.2%). CONCLUSION: BPD showed early effectiveness in weight loss and co-morbidity improvement. Calorie, protein, oligoelement and vitamin dietary intakes were below recommendations, so that strict multidisciplinary follow-up and supplementation to prevent or treat nutritional deficiencies are mandatory.

Relation between conditioned stimulus-elicit responses and unconditioned response diminution in long-interval human heart-rate classical conditioning.

Previous research on electrodermal conditioning suggests that the conditioned diminution of the unconditioned response (UR) has an associative basis. The aim of this experiment was to test whether this phenomenon also occurs in heart rate (HR) classical conditioning. For this purpose, a differential classical conditioning was performed. The conditioned stimuli (CSs) were geometrical shapes (the CS+ was a square and the CS- was a triangle) displayed on a computer screen and a burst of white noise was used as unconditioned stimulus (US). For analysis of the conditioned response (CR) components, an interval between CS+ and US of 8 seconds was used. After the acquisition phase, participants were tested using trials with the US preceded either by a CS+, a CS-, or a neutral stimulus (a circle). The results showed conditioned diminution of the UR and suggest that the second heart rate deceleration component (D2) is responsible for the occurrence of this phenomenon.

Emotionality of words as related to vividness of imagery and concreteness.

We investigated the association of the imagery and concreteness of words on their emotionality. Emotionality was evaluated on the basis of skin conductance. A total of 61 subjects (all university students) rated the vividness of imagery and concreteness of the words in a list of 25 word pairs. Each pair was comprised of one abstract word and one concrete word with a related meaning, e.g., "friendship" and "friend," thereby controlling meaning. The skin-conductance response of each word was measured subsequently from these same subjects. Our results show that both imagery and concreteness were significantly related to emotionality.

Effects of CS-US interval modification on diminution of the unconditioned response in electrodermal classical conditioning.

The purpose of this experiment was to study whether interstimulus interval (ISI) modification differentially affects the amplitude of the unconditioned response (UR amp.). Seventy-five volunteer subjects received discrimination training with an interval between conditioned stimulus (CS) and unconditioned stimulus (US; aversive white noise) of 8 s. After the discrimination training phase, subjects exhibiting discriminative control were randomized into three groups that differed according to the ISI, of 1, 5 or 8 s. The subjects of each group were then tested with five presentations of CS + /US. The results demonstrate that the UR showed a greater amplitude when an ISI of 8 s was used than with ISIs of 1 or 5 s. No significant differences were found between the UR amp. of the 1- and 5-s ISI groups. These findings are discussed as a result of a hypothetical experimentally induced blend of the anticipatory CRs with the UR.

Effects of conditioned stimulus presentation on diminution of the unconditioned response in aversive classical conditioning.

The purpose of this experiment was to study whether conditioned diminution of the unconditioned response (UR) is a phenomenon with an associative basis. Discriminative electrodermal conditioning was used with an interval between the conditioned stimulus (CS) and unconditioned stimulus (US; aversive white-noise) of 8 s. Fifty-nine volunteer subjects received discrimination training in which one CS was reinforced (CS+ /US) and a second CS was non-reinforced (CS-). After this discriminative training phase, participants were tested using intermixed trials in which a US was preceded by either a CS+, a CS-, or a neutral stimulus (NS). The results indicated that the skin conductance response amplitude of the UR was lower when the US was preceded by the CS+ than when the US was preceded by the CS- or the NS. However, NS/US presentations elicited URs of greater amplitude than those of the CS- /US presentations. The results can be explained in terms of orienting reflex reinstatement. In addition, it is argued that conditioned diminution has an associative basis.

Relationship between properties of words and elicitation of skin conductance response.

We investigated the association of subject-rated imagery, subject-rated concreteness, subject-rated emotionality, frequency, date of entry into the language, and word length with emotional imagery as measured by the skin conductance response elicited by that word. 50 words in a list of 25 word-pairs were rated by 96 university students; then their skin conductance response of each word was measured for each word. In each pair, one word was concrete and one was abstract but with related meaning, e.g., adolescent and adolescence. Stepwise multiple regression indicated that 30% of variance in the later skin conductance response was explained by imagery and subject-rated emotionality. Imagery alone explained 24% of variance.

Importance of surveillance mycobacterial cultures after liver transplantation.

The routine use of isoniazid prophylaxis after liver transplantation is a controversial issue because the benefits must be weighed against the risk of hepatotoxicity. We decided not to institute isoniazid prophylaxis but to study the efficacy of a surveillance mycobacterial program. One hundred patients were included in the protocol. Sputum and urine samples were processed before transplantation and on days 15, 30, 60, 90, 12, 150, and 180 for acid-fast stain and culture. One case of tuberculosis was promptly identified and successfully treated. Cases of tuberculosis with negative surveillance cultures were not identified. Our approach indicates that surveillance mycobacterial cultures can permit rapid identification of tuberculosis after liver transplantation and it is an alternative for groups who questioned isoniazid prophylaxis.