Self-assembled films from WO(3): Electrochromism and lithium ion diffusion

WO(3)/chitosan and WO(3)/chitosan/poly(ethylene oxide) (PEO) films were prepared by the layer-by-layer method. The presence of chitosan enabled PEO to be carried into the self-assembled structure, contributing to an increase in the Li(+) diffusion rate. On the basis of the galvanostatic intermittent titration technique (GITT) and the quadratic logistic equation (QLE), a spectroelectrochemical method was used for determination of the ""optical"" diffusion coefficient (D(op)), enabling analysis of the Li(+) diffusion rate and, consequently, the coloration front rate in these host matrices. The D(op) values within the WO(3)/chitosan/PEO film were significantly higher than those within the WO(3)/chitosan film, mainly for higher values of injected charge. The presence of PEO also ensured larger accessibility to the electroactive sites, in accordance with the method employed here. Hence, this spectroelectrochemical method allowed us to separate the contribution of the diffusion process from the number of accessible electroactive sites in the materials, thereby aiding a better understanding of the useful electrochemical and electrochromic properties of these films for use in electrochromic devices. (C) 2010 Elsevier B.V. All rights reserved.

Spectroelectrochemical Properties and Lithium Ion Storage in Self-Assembled Nanocomposites from TiO(2)

Layer-by-layer (LbL) nanocomposite films from TiO(2) nanoparticles and tungsten-based oxides (WO(x)H(y)), as well as dip-coating films of TiO(2) nano particles, were prepared and investigated by electrochemical techniques under visible light beams, aiming to evaluate the lithium ion storage and chromogenic properties. Atomic force microscopy (AFM) images were obtained for morphological characterization of the Surface of the materials, which have similar roughness. Cyclic voltammetry and chronoamperometry measurements indicated high storage capacity of lithium ions in the LbL nanocomposite compared with the dip-coating film, which was attributed to the faster lithium ion diffusion rate within the self-assembled matrix. On the basis of the data obtained from galvanostatic intermittent titration technique (GITT), the values of lithium ion diffusion coefficient (D(Li)) for TiO(2)/WO(x)H(y) were larger compared with those for TiO(2). The rate of the coloration front in the matrices was investigated using a spectroelectrochemical method based oil GITT, allowing the determination of the ""optical"" diffusion coefficient (D(op)) as a function of the amount of lithium ions previously inserted into the matrices. The Values of D(Li) and D(op) suggested the existence of phases with distinct contribution to lithium ion diffusion rates and electrochromic efficiency. Moreover, these results aided a better understanding of the temporal change of current density and absorbance during the ionic electro-insertion, which is important for the possible application of these materials in lithium ion batteries and electrohromic devices.

Effects of Self-Assembled Materials Prepared from V(2)O(5) for Lithium Ion Electroinsertion

Self-assembled materials consisting of V(2)O(5), polyallylamine (PAR) and silver nanoparticles (AgNPs) were obtained by the layer-by-layer (LbL) method, aiming at their application as electrodes for lithium-ion batteries and electrochromic devices. The method employed herein allowed for linear growth of visually homogeneous films composed of V(2)O(5), V(2)O(5)/PAH, and V(2)O(5)/PAH/AgNP with 15 bilayers. According to the Fourier transform infrared spectra, interaction between the oxygen atom of the vanadyl group and the amino group should be responsible for the growth of these films. This interaction also enabled establishment of an electrostatic shield between the lithium ions and the sites with higher negative charge, thereby raising the ionic mobility and consequently increasing the energy storage capacity and reducing the response time. According to the site-saturation model and the electrochemical and spectroelectrochemical results, the presence of PAH in the self-assembled host matrix decreased the number of V(2)O(5) electroactive sites. Thus, AgNPs were stabilized in PAR and inserted into the nanoarchitecture, so as to enhance the specific capacity. This should provide new conducting pathways and connect isolated V(2)O(5) particles in the host matrix. Therefore, new nanoarchitectures for specific interactions were formed spontaneously and chosen as examples in this work, aiming to demonstrate the potentiality of the adopted self-assembled method for enhancing the charge transport rate into the host matrices. The obtained materials displayed suitable properties for use as electrodes in lithium batteries and electrochromic devices.

Anti-Group A Streptococcal Vaccine Epitope STRUCTURE, STABILITY, AND ITS ABILITY TO INTERACT WITH HLA CLASS II MOLECULES

Streptococcus pyogenes infections remain a health problem in several countries due to poststreptococcal sequelae. We developed a vaccine epitope (StreptInCor) composed of 55 amino acids residues of the C-terminal portion of the M protein that encompasses both T and B cell protective epitopes. The nuclear magnetic resonance (NMR) structure of the StreptInCor peptide showed that the structure was composed of two microdomains linked by an 18-residue alpha-helix. A chemical stability study of the StreptInCor folding/unfolding process using far-UV circular dichroism showed that the structure was chemically stable with respect to pH and the concentration of urea. The T cell epitope is located in the first microdomain and encompasses 11 out of the 18 alpha-helix residues, whereas the B cell epitope is in the second microdomain and showed no alpha-helical structure. The prediction of StreptInCor epitope binding to different HLA class II molecules was evaluated based on an analysis of the 55 residues and the theoretical possibilities for the processed peptides to fit into the P1, P4, P6, and P9 pockets in the groove of several HLA class II molecules. We observed 7 potential sites along the amino acid sequence of StreptInCor that were capable of recognizing HLA class II molecules (DRB1*, DRB3*, DRB4*, and DRB5*). StreptInCoroverlapping peptides induced cellular and humoral immune responses of individuals bearing different HLA class II molecules and could be considered as a universal vaccine epitope.

Non-pharmacological approach to neuropathic pain: the use of repetitive transcranial magnetic stimulation

Neuromodulation is the branch of neurophysiology related to the therapeutic effects of electrical stimulations of the nervous system. There are currently different practical applications of neuromodulation techniques for the treatment of various neurological disorders, such as deep brain stimulation for Parkinson`s disease and repetitive transcranial magnetic stimulation (rTMS) for major depression. An increasing number of studies have been devoted to the analgesic effects of rTMS in chronic pain patients. RTMS has been used either as a therapeutic tool per se, or as a preoperative test in patients undergoing epidural precentral gyrus stimulation. High-frequency rTMS (a parts per thousand yen5 Hz) is considered to be excitatory, while low-frequency stimulation (a parts per thousand currency sign1 Hz) is considered to exert an inhibitory effect over neuronal populations of the primary motor cortex. However, other parameters of stimulation may play a central role on its clinical effects such as the type of coil, its orientation over the scalp, and the total number of rTMS sessions performed. Experimental data from animals, healthy volunteers, and neuropathic pain patients have suggested that stimulation of the primary motor cortex by rTMS is able to activate brain regions implicated in the processing of the different aspects of chronic pain, and influence brain regions involved in the endogenous opioid system. Over twenty prospective randomized sham-controlled trials have studied the analgesic effects of rTMS on chronic pain. Most of the patients included in these trials had central or peripheral neuropathic pain. Although most studies used a single session of stimulation, recent studies have shown that the analgesic effects of rTMS may outlast the stimulation period for many days when repetitive sessions are performed. This opens the possibility to use rTMS as a therapeutic tool of its own in the armamentarium against neuropathic pain.

Cross-reactive IgE antibody responses to tropomyosins from Ascaris lumbricoides and cockroach

Background: Evidence indicates that infection with Ascaris lumbricoides may promote development of allergy and asthma. Objective: To study the role of tropomyosin, a pan-allergen in invertebrates, in IgE responses to A lumbricoides. Methods: Recombinant A lumbricoides and Periplaneta americana tropomyosins were expressed in Pichia pastoris. Levels of IgE to tropomyosins from A lumbricoides and P americana were determined by chimeric ELISA in sera from 119 children living in a parasite-endemic area and 112 patients with cockroach allergy from the allergy clinics. Presence of tropomyosin in A lumbricoides larvae at L3 stage was evaluated by immunofluorescence using mAb IA6, directed against mite tropomyosin. Molecular modeling of P americana and A lumbricoides tropomyosins was performed by using the MODELLER program. Results: A lumbricoides tropomyosin showed 69% to 98% sequence identity to tropomyosins from other invertebrates. The predicted structure of A lumbricoides tropomyosin was similar to that of P americana tropomyosin and showed the characteristic coiled-coil structure. Strong correlation was found for IgE antibodies to tropomyosins from A lumbricoides and P americana in sera from children living in a parasite-endemic area and from patients with cockroach allergy. Larvae of A lumbricoides reacted strongly with mAb IA6. Conclusion: Tropomyosin induces IgE responses in A lumbricoides-infected children and in patients allergic to cockroach.

Antimicrobial Activities of Indole Alkaloids from Tabernaemontana catharinensis

Tabernaemontana catharinensis root bark ethanol extract, EB2 fraction and the MMV alkaloid (12-methoxy-4-methylvoachalotine) were evaluated for their antimicrobial activities. T. catharinensis ethanol extract was effective against both strains of the dermatophyte Trichophyton rubrum at concentrations of 2.5 mg/mL (wild strain) and 1.25 mg/mL (mutant strain), while the EB2 fraction and MMV alkaloid showed a strong antifungal activity against wild and mutant strains with MIC values of <0.02 and 0.16 mg/mL, respectively. The EB2 fraction showed a strong antibacterial activity against ATCC strains of S. aureus, S. epidermidis, E. coli and P. aeruginosa with MICs from <0.02 to 0.04 mg/mL, as well as against resistant clinical isolates species of Enterococcus sp, Klebsiella oxytoca, Citrobacter, K. pneumoniae, P. mirabilis, S. aureus, S. epidermidis, E. coli and P. aeruginosa with MIC values ranging from 0.04 to 0.08 mg/mL. The MMV alkaloid presented a MIC of 0.16 mg/mL against the strains of S. aureus and E. coli ATCC. For the resistant clinical isolates Enterococcus sp, Citrobacter, S. aureus, S. epidermidis, E. coil and P. aeruginosa the MIC of MMV ranged from 0.08 to 0.31 mg/mL. The chromatography analysis of the EB2 fraction revealed the presence of indole alkaloids, including MMV, possibly responsible for the observed antimicrobial activity.

Modeling upper eyelid kinematics during spontaneous and reflex blinks

To test a mathematical model for measuring blinking kinematics. Spontaneous and reflex blinks of 23 healthy subjects were recorded with two different temporal resolutions. A magnetic search coil was used to record 77 blinks sampled at 200 Hz and 2 kHz in 13 subjects. A video system with low temporal resolution (30 Hz) was employed to register 60 blinks of 10 other subjects. The experimental data points were fitted with a model that assumes that the upper eyelid movement can be divided into two parts: an impulsive accelerated motion followed by a damped harmonic oscillation. All spontaneous and reflex blinks, including those recorded with low resolution, were well fitted by the model with a median coefficient of determination of 0.990. No significant difference was observed when the parameters of the blinks were estimated with the under-damped or critically damped solutions of the harmonic oscillator. On the other hand, the over-damped solution was not applicable to fit any movement. There was good agreement between the model and numerical estimation of the amplitude but not of maximum velocity. Spontaneous and reflex blinks can be mathematically described as consisting of two different phases. The down-phase is mainly an accelerated movement followed by a short time that represents the initial part of the damped harmonic oscillation. The latter is entirely responsible for the up-phase of the movement. Depending on the instantaneous characteristics of each movement, the under-damped or critically damped oscillation is better suited to describe the second phase of the blink. (C) 2010 Elsevier B.V. All rights reserved.

Spontaneous Blinking in Patients With Graves` Upper Eyelid Retraction

Purpose: To describe spontaneous blink kinematics in Graves` upper eyelid retraction (UER). Methods: The magnetic search coil technique was used to record spontaneous blinks of 15 healthy subjects (aged 23-56 years, 15 eyelids) and 15 patients with Graves` UER (aged 22-62 years, 15 eyelids) during a 5-min period of video observation, and the signals were digitized at 200 Hz (12 bits). Overall, a total of 2,798 blinks were recorded for the controls and 1,860 for the patients. The distance between pupil center and upper eyelid margin in the primary position of gaze (MRD) was measured with the Image J software. Results: The blinking rate of patients was lower than that of control subjects, with a mean (+/-SEM) blinking rate (blinks/min) of 13.0 +/- 1.7 for patients and of 20.0 +/- 2.1 for the controls (t = 2.58, P = 0.016). There were no statistically significant differences in blink amplitude between controls (22.7 +/- 3.1 degrees) and Graves` patients (24.7 +/- 3.3 degrees). However, while only 22% of the blinks performed by controls were smaller than MRD, this rate was 78% for patients. In addition, in blinks larger than 25, patients showed lower down-phase velocity than controls. Conclusions: Patients with Graves` UER show reduced blinks rates and abnormal blink kinematics, which might be related to the development of exposure keratitis in this disease.

Spontaneous Interblink Time Distributions in Patients with Graves` Orbitopathy and Normal Subjects

PURPOSE. To determine the shape of spontaneous interblink time interval distributions obtained in a long observation period in normal subjects and patients with Graves` orbitopathy. METHODS. The magnetic search coil technique was used to register the spontaneous blinking activity during 1 hour of video observation of two groups of 10 subjects each (normal controls aged 27-61 years, mean +/- SD = 46.0 +/- 13.6; patients with Graves` orbitopathy aged 33-61 years, mean +/- SD +/- 46.7 +/- 8.9). The spontaneous blink rate of each subject was calculated for the entire period of observation and for 56 five-minute bins. Histograms of the interblink time interval were plotted for each measurement of blink rate. RESULTS. Neither the overall mean blink rate (controls, 19.8 +/- 4.9; Graves`, 17.6 +/- 5.4) nor the interblink time (controls, 5.2 +/- 3.1, Graves`, 7.9 +/- 3.5) differed between the two groups. There was a large variation of both measurements when the 5-minute bins were considered. The interblink time distribution of all subjects was highly positively skewed when the 1-hour period was measured. A significant number of the 5-minute bin distributions deviated from the overall pattern and became symmetric. CONCLUSIONS. The normal blinking process is characterized by highly positively skewed interblink time distributions. This result means that most blinks have a short time interval, and occasionally a small number of blinks have long time intervals. The different patterns of distribution described in the early literature probably represent artifacts because of the small samples analyzed. (Invest Ophthalmol Vis Sci. 2011;52:3419-3424) DOI:10.1167/iovs.10-7060

Effects of intrapulpal temperature change induced by visible light units on the metabolism of odontoblast-like cells

Purpose: To investigate the effects of intrapulpal temperature changes induced by a quartz tungsten halogen (QTH) and a light emitting diode (LED) curing units on the metabolism of odontoblast-like cells. Methods: Thirty-six 0.5 mm-thick dentin discs obtained from sound human teeth were randomly assigned into three groups: QTH, LED and no light (control). After placement of the dentin discs in pulp chamber devices, a thermistor was attached to the pulpal surface of each disc and the light sources were applied on the occlusal surface. After registering the temperature change, odontoblast-like cells MDPC-23 were seeded on the pulpal side of the discs and the curing lights were again applied. Cell metabolism was evaluated by the MTT assay and cell morphology was assessed by SEM. Results: In groups QTH and LED the intrapulpal temperature increased by 6.4 degrees C and 3.4 degrees C, respectively. The difference between both groups was statistically significant (Mann-Whitney; P< 0.05). QTH and LED reduced the cell metabolism by 36.4% and 33.4%, respectively. Regarding the cell metabolism, no statistically significant difference was observed between both groups (Mann-Whitney; P> 0.05). However, when compared to the control, only QTH significantly reduced the cell metabolism (Mann-Whitney; P< 0.05). It was concluded that the irradiance of 0.5 mm-thick human dentin discs with a QTH in comparison to a LED curing unit promoted a higher temperature rise, which propagates through the dentin negatively affecting the metabolism of the underlying cultured pulp cells. (Am J Dent 2009;22:151-156).

Spontaneous Eyeblink Activity

Spontaneous blinking is essential for maintaining a healthy ocular surface and clarity of vision. The spontaneous blink rate (SBR) is believed to reflect a complex interaction between peripheral influences mediated by the eye surface and the central dopaminergic activity. The SBR is thus extremely variable and dependent on a variety of psychological and medical conditions. Many different methods have been employed to measure the SBR and the upper eyelid kinematics during a blink movement. Each has its own merits and drawbacks, and the choice of a specific method should be tailored to the specific needs of the investigation. Although the sequence of muscle events that leads to a blink has been fully described, knowledge about the neural control of spontaneous blinking activity is not complete. The tear film is dynamically modified between blinks, and abnormalities of the blink rate have an obvious influence on the ocular surface.

Does a final rinse to remove smear layer interfere on dentin permeability of root canals?

Objective. The objective of this study was to assess the influence of different final irrigating solutions on dentin permeability and smear layer removal using the same specimens and relate the results obtained. Study design. Forty anterior human teeth were instrumented and divided into 4 groups (n = 10) at the final rinse step, according to the irrigant used: G I (control) - 1% NaOCl; G II - 17% EDTA; G III - 17% EDTAT; and G IV - Biopure MTAD. The canals were filled with 0.5% methylene blue and maintained in bottles for 48 hours. The roots were transversally split in coronal, middle, and apical fragments. The specimens were photographed and analyzed regarding dye penetration. The fragments were then axially split and prepared for SEM. The photomicrographs were analyzed and qualified by scores. Results. Only the EDTA-T group exhibited statistical difference in which the apical third had less dentin permeability (P < .05). When a decalcifying agent was used, smear layer was removed, which did not happen in the NaOCl group. Regarding smear layer removal, differences were found only in the EDTA group in which the apical third presented more smear layer (P < .05). No correlation was found for both studies (r = 0.4207). Conclusions. There was not an even relationship between the results from both studies, which inferes that higher or lower dentinal permeability does not necessarily correspond to a higher or lower amount of smear layer. The analysis of dentin permeability and smear layer removal was shown to be a feasible procedure using the same specimens. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: e47-e51)

Influence of different volumes of EDTA for final rinse on smear layer removal

Objective. The aim of this study was to analyze the influence of different volumes of 17% EDTA for final rinse on smear layer removal on the different areas of the root canal. Study design. Forty single-rooted teeth were instrumented using rotary instruments. The teeth were divided into 3 test groups according to the EDTA volume for final rinse (5 mL, 10 mL, 15 mL) and 1 control group (10 mL of 1% sodium hypochlorite). The roots were axially split into halves, and the smear layer removal from the canals was determined under scanning electron microscope. The data were analyzed using Kruskal Wallis and Dunn tests. Results. The 3 experimental groups showed no statistical difference (P > .05); however, when the test groups were compared to the control group statistically significant differences were found (P < .01). The root canal wall surfaces of teeth in the control group showed the presence of heavy smear layer through the entire length of the root canals. The other groups showed mainly smear layer-free surfaces or a small amount of debris. When coronal, middle and apical thirds were compared, there was no statistically significant difference (P > .05). Conclusions. Based on the results, it appears that a final rinse with 5 mL of EDTA per canal provides good smear layer removal, with root canal walls free of debris and mostly open dentinal tubules in all areas. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:e40-e43)

Failure modes of Y-TZP crowns at different cusp inclines

Objectives To compare the reliability of the disto-facial (DF) and mesio-lingual (ML) cusps of an anatomically correct zirconia (Y-TZP) crown system The research hypotheses tested were (1) fatigue reliability and failure mode are similar for the ML and DF cusps, (2) failure mode of one cusp does not affect the failure of the other Methods The average dimensions of a mandibular first molar crown were imported into CAD software, a tooth preparation was modelled by 1 5 mm marginal high reduction of proximal walls and occlusal surface by 2 0 mm The CAD-based tooth preparation was milled and used as a die to fabricate crowns (n = 14) with porcelain veneer on a 0 5 mm Y-TZP core. Crowns were cemented on composite reproductions of the tooth preparation The crowns were step-stress mouth motion fatigued with sliding (0 7 mm) a tungsten-carbide indenter of 6 25 mm diameter down on the inclines of either the DF or ML cusps Use level probability Weibull curve with use stress of 200 N and the reliability for completion of a mission of 50,000 cycles at 200 N load were calculated Results Reliability for a 200 N at 50,000 cycles mission was not different between tested cusps SEM imaging showed large cohesive failures within the veneer for the ML and smaller for the DF Fractures originated from the contact area regardless of the cusp loaded Conclusion No significant difference on fatigue reliability was observed between the DF compared to the ML cusp Fracture of one cusp did not affect the other (c) 2010 Elsevier Ltd All rights reserved