Bipolar Tribocharging Signal During Friction Force Fluctuations At Metal-insulator Interfaces.

Friction and triboelectrification of materials show a strong correlation during sliding contacts. Friction force fluctuations are always accompanied by two tribocharging events at metal-insulator [e.g., polytetrafluoroethylene (PTFE)] interfaces: injection of charged species from the metal into PTFE followed by the flow of charges from PTFE to the metal surface. Adhesion maps that were obtained by atomic force microscopy (AFM) show that the region of contact increases the pull-off force from 10 to 150 nN, reflecting on a resilient electrostatic adhesion between PTFE and the metallic surface. The reported results suggest that friction and triboelectrification have a common origin that must be associated with the occurrence of strong electrostatic interactions at the interface.

Effect Of Composite Containing An Iodonium Salt On The Bond Strength Of Brackets To Bovine Enamel.

This study investigated the effect of the incorporation of an iodonium salt in experimental composites, on the bond strength of metallic brackets bonded to bovine teeth. Two hundred and seventy bovine teeth were embedded in self-curing acrylic resin and divided into 18 groups (n=15), according to the experimental composite with an iodonium salt at molar concentrations 0 (control), 0.5, or 1%; the light-activation times (8, 20 and 40 s); and the storage times (10 min or 24 h). Metallic brackets were fixed on the tooth surface using experimental composites. Photoactivation was performed with a quartz-tungsten-halogen light-curing unit curing unit for 8, 20 and 40 s. The specimens were stored in distilled water at 37 °C for 10 min or 24 h and submitted to bond strength test at 0.5 mm/min. The data were subjected to three-way ANOVA and Tukey's test (α=0.05). The Adhesive Remnant Index (ARI) was used to classify the failure modes. The shear bond strengths (MPa) at 10 min for light-activation times of 8, 20 and 40 s were: G1 - 4.6, 6.9 and 7.1; G2 - 8.1, 9.2 and 9.9; G3 - 9.1, 10.4 and 10.7; and at 24 h were: G1 - 10.9, 11.1 and 11.7; G2 - 11.8, 12.7 and 14.2; G3 - 12.1, 14.4 and 15.8. There was a predominance of ARI score 3 for groups with 10 min storage time, and ARI score 2 for groups with 24 h storage time. In conclusion, the addition of iodonium salt (C05 and C1) to the experimental composite may increase the bond strength of brackets to bovine enamel using reduced light exposure times.

Avoiding Pitfalls Of Intraoperative Peripheral Endovascular Surgery With The Aid Of Osirix: Expanding The Use Of Virtual Fluoroscopy.

We have shown how the analysis of the angiotomography reconstruction through OsiriX program has assisted in endovascular perioperative programming. We presented its application in situations when an unexpected existence of metallic overlapping artifact (orthopedic osteosynthesis) compromised the adequate visualization of the arterial lesion during the procedure. Through manipulation upon OsiriX software, with assistance of preview under virtual fluoroscopy, it was possible to obtain the angles that would avoid this juxtaposition. These angles were reproduced in the C-arm, allowing visualization of the occluded segment, reducing the need for repeated image acquisitions and contrast overload, allowing the continuation of the procedure.

Comparison Of Different Transfer Impression Techniques Accuracy For Osseointegrated Implants.

Abstract The aim of this study was to evaluate three transfer techniques used to obtain working casts of implant-supported prostheses through the marginal misfit and strain induced to metallic framework. Thirty working casts were obtained from a metallic master cast, each one containing two implant analogues simulating a clinical situation of three-unit implant-supported fixed prostheses, according to the following transfer impression techniques: Group A, squared transfers splinted with dental floss and acrylic resin, sectioned and re-splinted; Group B, squared transfers splinted with dental floss and bis-acrylic resin; and Group N, squared transfers not splinted. A metallic framework was made for marginal misfit and strain measurements from the metallic master cast. The misfit between metallic framework and the working casts was evaluated with an optical microscope following the single-screw test protocol. In the same conditions, the strain was evaluated using strain gauges placed on the metallic framework. The data was submitted to one-way ANOVA followed by the Tukey's test (α=5%). For both marginal misfit and strain, there were statistically significant differences between Groups A and N (p<0.01) and Groups B and N (p<0.01), with greater values for the Group N. According to the Pearson's test, there was a positive correlation between the variables misfit and strain (r=0.5642). The results of this study showed that the impression techniques with splinted transfers promoted better accuracy than non-splinted one, regardless of the splinting material utilized.

Strain Gauges's Analysis On Implant-retained Prosthesis' Cast Accuracy.

A proper cast is essential for a successful rehabilitation with implant prostheses, in order to produce better structures and induce less strain on the implants. The aim of this study was to evaluate the precision of four different mold filling techniques and verify an accurate methodology to evaluate these techniques. A total of 40 casts were obtained from a metallic matrix simulating three unit implant-retained prostheses. The molds were filled using four different techniques in four groups (n = 10): Group 1 - Single-portion filling technique; Group 2 - Two-step filling technique; Group 3 - Latex cylinder technique; Group 4 - Joining the implant analogs previously to the mold filling. A titanium framework was obtained and used as a reference to evaluate the marginal misfit and tension forces in each cast. Vertical misfit was measured with an optical microscope with an increase of 120 times following the single-screw test protocol. Strain was quantified using strain gauges. Data were analyzed using one-way ANOVA (Tukey's test) (α =0.05). The correlation between strain and vertical misfit was evaluated by Pearson test. The misfit values did not present statistical difference (P = 0.979), while the strain results showed statistical difference between Groups 3 and 4 (P = 0.027). The splinting technique was considered to be as efficient as the conventional technique. The strain gauge methodology was accurate for strain measurements and cast distortion evaluation. There was no correlation between strain and marginal misfit.

Analysis Of Cellular Adhesion On Superhydrophobic And Superhydrophilic Vertically Aligned Carbon Nanotube Scaffolds.

We analyzed GFP cells after 24h cultivated on superhydrophilic vertically aligned carbon nanotube scaffolds. We produced two different densities of VACNT scaffolds on Ti using Ni or Fe catalysts. A simple and fast oxygen plasma treatment promoted the superhydrophilicity of them. We used five different substrates, such as: as-grown VACNT produced using Ni as catalyst (Ni), as-grown VACNT produced using Fe as catalyst (Fe), VACNT-O produced using Ni as catalyst (NiO), VACNT-O produced using Fe as catalyst (FeO) and Ti (control). The 4',6-diamidino-2-phenylindole reagent nuclei stained the adherent cells cultivated on five different analyzed scaffolds. We used fluorescence microscopy for image collect, ImageJ® to count adhered cell and GraphPad Prism 5® for statistical analysis. We demonstrated in crescent order: Fe, Ni, NiO, FeO and Ti scaffolds that had an improved cellular adhesion. Oxygen treatment associated to high VACNT density (group FeO) presented significantly superior cell adhesion up to 24h. However, they do not show significant differences compared with Ti substrates (control). We demonstrated that all the analyzed substrates were nontoxic. Also, we proposed that the density and hydrophilicity influenced the cell adhesion behavior.

Photocatalytic Degradation Of Ofloxacin And Evaluation Of The Residual Antimicrobial Activity.

Ofloxacin is an antimicrobial agent frequently found in significant concentrations in wastewater and surface water. Its continuous introduction into the environment is a potential risk to non-target organisms or to human health. In this study, ofloxacin degradation by UV/TiO2 and UV/TiO2/H2O2, antimicrobial activity (E. coli) of samples subjected to these processes, and by-products formed were evaluated. For UV/TiO2, the degradation efficiency was 89.3% in 60 min of reaction when 128 mg L(-1) TiO2 were used. The addition of 1.68 mmol L(-1) hydrogen peroxide increased degradation to 97.8%. For UV/TiO2, increasing the catalyst concentration from 4 to 128 mg L(-1) led to an increase in degradation efficiency. For both processes, the antimicrobial activity was considerably reduced throughout the reaction time. The structures of two by-products are presented: m/z 291 (9-fluoro-3-methyl-10-(methyleneamino)-7-oxo-2,3-dihydro-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid) and m/z 157 ((Z)-2-formyl-3-((2-oxoethyl)imino)propanoic acid).

Aspectos técnicos da monitorização da pressão intracraniana pelo método subaracnóideo no traumatismo craniencefálico grave

Two hundred and six patients with severe head injury (Glasgow Coma Scale of 8 points or less after nonsurgical resuscitation on admission), managed at Intensive Care Unit-Hospital das Clínicas - Universidade Estadual de Campinas were prospectively analysed. All patients were assessed by CT scan and 72 required neurosurgical intervention. All patients were continuously monitored to evaluate intracranial pressure (ICP) levels by a subarachnoid device (11 with subarachnoid metallic bolts and 195 with subarachnoid polyvinyl catheters). The ICP levels were continuously observed in the bedside pressure monitor display and their end-hour values were recorded in a standard chart. The patients were managed according to a standard protocol guided by the ICP levels. There were no intracranial haemorrhagic complications or hematomas due the monitoring method. Sixty six patients were punctured by lateral C1-C2 technique to assess infectious complications and 2 had positive cerebrospinal fluid samples for Acinetobacter sp. The final results measured at hospital discharge showed 75 deaths (36,40%) and 131 (63,60%) survivors. ICP levels had significantly influenced the final results (p<0,001). The subarachnoid method to continuously assess the ICP levels was considered aplicable, safe, simple, low cost and useful to advise the management of the patients. The ICP record methodology was practical and useful. Despite the current technical advances the subarachnoid method was considered viable to assess the ICP levels in severe head injury.

Comparação da eficiência do processo de ozonização e ozonização catalítica (Mn II e Cu II) na degradação de fenol

This paper discusses the results obtained with homogeneous catalytic ozonation [Mn (II) and Cu (II)] in phenol degradation. The reduction of total phenols and total organic carbon (TOC) and the ozone consumption were evaluated. The efficiency in phenol degradation (total phenol removal) at pH 3, with the catalytic process (Mn (II)), increased from 37% to 55% while the TOC removal increased from 4 to 63% in a seven-minute treatment. The ozonation process efficiency at pH 10 was 43% and 39% for phenol and TOC removal, respectively. The presence of both metallic ions (Mn2+ and Cu+2) in the ozonation process resulted in a positive effect.

Classificação de água de coco processada e natural por meio de HCA, PCA e teores de íons metálicos determinados por ICP OES

Inductively Coupled Plasma Optical Emission Spectrometry was used to determine Ca, Mg, Mn, Fe, Zn and Cu in samples of processed and natural coconut water. The sample preparation consisted in a filtration step followed by a dilution. The analysis was made employing optimized instrumental parameters and the results were evaluated using methods of Pattern Recognition. The data showed common concentration values for the analytes present in processed and natural samples. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) indicated that the samples of different kinds were statistically different when the concentrations of all the analytes were considered simultaneously.

Otimização das condições de produção de ésteres etílicos a partir de óleo de peixe com elevado teor de ácidos graxos ômega-3

The production of ethyl esters by alcoholysis is an alternative for splitting triacylglycerols due to the possibility of using low temperatures, which results in oxidative protection of the polyunsaturated fatty acids. Ethyl esters produced under mild conditions of temperature could be used as substrate for obtaining structured lipids. The reaction parameters of production of ethyl esters from fish oil with high content of omega-3 fatty acids by alcoholysis were optimized using response surface methodology. An experimental design (2³) (with levels +1 and -1, six axial points with levels -alpha and +alpha and three central points) was applied. The variables investigated were concentration of catalyst, amount of ethyl alcohol and temperature. Ethyl ester conversion was monitored by high performance size exclusion chromatography (HPSEC) and the best result obtained was 95% conversion rate. The optimal conditions were 40 °C, 1% of NaOH and 36% of ethanol.

Quantificação de antimônio em garrafas de politereftalato de etileno (PET) brasileiras por fluorescência de raios-X e avaliação quimiométrica para verificar a presença de pet reciclado através do teor de ferro

Antimony is a common catalyst in the synthesis of polyethylene terephthalate used for food-grade bottles manufacturing. However, antimony residues in final products are transferred to juices, soft drinks or water. The literature reports mentions of toxicity associated to antimony. In this work, a green, fast and direct method to quantify antimony, sulfur, iron and copper, in PET bottles by X-ray fluorescence spectrometry is presented. 2.4 to 11 mg Sb kg-1 were found in 20 samples analyzed. The coupling of the multielemental technique to chemometric treatment provided also the possibility to classify PET samples between bottle-grade PET/recycled PET blends by Fe content.

Variabilidade dos indicadores antropométricos e de desempenho físico de jovens futebolistas em função da idade cronológica

Universidade Estadual de Campinas . Faculdade de Educação Física

Qualidade de vida e avaliação fisica em intoxicados por mercurio : estudo observacional transversal descritivo

Universidade Estadual de Campinas . Faculdade de Educação Física

Um estudo das políticas públicas de lazer de Brotas/SP = : Brotas leisure public policies, São Paulo State

Universidade Estadual de Campinas . Faculdade de Educação Física