Experimental measurements of the NOx and CO concentrations operating in oscillatory and non-oscillatory burning conditions

The effects of combustion driven acoustic oscillations in carbon monoxide and nitrogen oxides emission rates of a combustor operated with liquefied petroleum gas (LPG) were investigated. Because the fuel does not contain nitrogen, tests were also conducted with ammonia injected in the fuel, in order to study the formation of fuel NOx. The main conclusions were: (a) the pulsating combustion process is more efficient than the non-pulsating one and (b) the pulsating combustion process generates higher rates of NOx, with and without ammonia injection, as shown by CO and NO concentrations as function of the O-2 concentration. An increase in the LPG flow rate, keeping constant the air to fuel ratio, increased the acoustic pressure amplitude and the frequency of oscillation. The injection of ammonia had no influence on either pressure amplitude or frequency. (c) 2005 Elsevier Ltd. All rights reserved.

Efeitos da fisioterapia respirat��ria convencional versus aumento do fluxo expirat��rio na satura����o de O2, freq����ncia card��aca e freq����ncia respirat��ria, em prematuros no per��odo p��s-extuba����o

INTRODU����O: Rec��m-nascidos (RN) prematuros apresentam elevada morbidade respirat��ria e necessidade de ventila����o mec��nica, assim, a fisioterapia respirat��ria �� parte integrante da assist��ncia neonatal. Objetivo: Comparar os efeitos da fisioterapia respirat��ria convencional (FRC) versus aumento do fluxo expirat��rio (AFE), na satura����o de O2 (SpO2), freq����ncia card��aca (FC) e na freq����ncia respirat��ria (FR) em prematuros no per��odo p��s-extuba����o. M��todo: Ensaio cl��nico randomizado realizado na UTI Neonatal do Hospital das Cl��nicas de BotucatuUNESP, comparando duas t��cnicas fisioterap��uticas, aplicadas em rec��m-nascidos prematuros, nas primeiras 48 horas p��s-extuba����o. Para a an��lise estat��stica foram utilizados o teste t Student, Mann-Whitney, Qui-quadrado e o teste exato de Fisher, com n��vel de signific��ncia em 5%. Resultados: Os dois grupos de estudo: Grupo FRC (n= 20) e grupo AFE (n= 20), n��o diferiram quanto �� idade gestacional (m��dia de 28 semanas) e peso de nascimento (m��dia de 1100 gramas). em ambos os grupos a s��ndrome do desconforto respirat��rio (SDR) foi o principal diagn��stico. A mediana da idade no in��cio da fisioterapia foi de sete dias no grupo AFE e 11 dias na FRC. Ambas as t��cnicas produziram aumento significativo da SpO2 aos 10 e 30 minutos, sem altera����es na FR. A FC aumentou significativamente ap��s a FRC e n��o se alterou ap��s o AFE. Conclus��o: Os resultados sugerem que o AFE �� menos estressante que a FRC e pode ser aplicado em prematuros no per��odo p��s-extuba����o. Nestes rec��m-nascidos o AFE parece ser seguro e ben��fico a curto prazo.

Altera����es do pH, da P O2 e da P CO2 arteriais e da concentra����o de lactato sang����neo de cavalos da ra��a ��rabe durante exerc��cio em esteira de alta velocidade

Avaliaram-se as altera����es do pH, da P O2 e da P CO2 do sangue arterial e da concentra����o de lactato sang����neo de 11 cavalos adultos da ra��a ��rabe, submetidos a exerc��cio progressivo em esteira de alta velocidade. Antes do exerc��cio, no intervalo dos 15 segundos finais de cada mudan��a de velocidade e aos 1, 3 e 5 minutos ap��s o t��rmino do exerc��cio foram coletadas amostras de sangue arterial e venoso para a mensura����o dos gases sang����neos e da concentra����o de lactato. O exerc��cio resultou em diminui����o do pH, da press��o parcial de O2 (P O2) e da press��o parcial de CO2 (P CO2). A concentra����o de lactato sang����neo elevou-se exponencialmente a partir da velocidade de 8,0m/s at�� os momentos ap��s t��rmino do exerc��cio.

Electronic ceramics based on polycrystalline SnO2, TiO2 and (Sn xTi1-x)O2 solid solution

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

EU3+-O2- associates luminescence in Ba2SiO4

Results on the luminescence properties of Eu3+ in Ba2SiO4 sites and the presence of Eu3+-O2- associates are reported. The Ba2SiO4:Eu3+ emission spectra showed two groups of transitions that might be assigned to the D-5(0) --> F-7(0) one. In each group at least two lines were observed. This is possibly related to the different emission centers, attributed to Eu3+ occupying the Ba2+ sites, and to Eu3+-O2- associates in interstices. Excitation spectra presented two CT bands at 270 and 340 nm related to each emission center.

Increase on incineration capacity and NOx control for air enrichment in the experimental simulation of aqueous residue incineration

An experimental investigation of air enrichment in a combustion chamber designed to incinerate aqueous residues is presented. Diesel fuel and liquefied petroleum gas (LPG) were used independently as fuels. An increase of 85% in the incineration capacity was obtained with nearly 50% O-2 in the oxidant gas, in comparison to incineration with air only. The incineration capacity continues increasing for enrichment levels above 50% O-2 , although at a lower pace. For complete oxy-flame combustion (100% O-2 ), the increase of the incineration capacity was about 110% relative to the starting conditions and about 13.5% relative to the condition with 50% O-2 . The CO concentration measured near the flame front decreases drastically with the increase of O-2 content in the oxidant gas. At the chamber exit, the CO concentration was always near zero, indicating that the chamber residence time was sufficient to complete fuel oxidation in any test setting. For diesel fuel, the NOx was entirely formed in the first region of the combustion chamber. For diesel fuel, there was some increase in the NOx concentration up to 35% of O-2 ; this increase became very sharp after that. From 60 ppm, at operation with air only, the NOx concentration raises to 200 ppm at 35% O-2 , and then to 2900 ppm at 74% O-2 . The latter corresponds to six times more NOx in terms of the ratio of mass of NO to mass of residue, compared to the situation of combustion with air only. For LPG, the NOx concentrations reached 4200 ppm at 80% O-2 , corresponding to nine times more, also in terms of the ratio of mass of NO to mass of residue, in comparison with combustion with air only. Results of different techniques used to control the NOx emission during air enrichment are discussed: (a) variation of the recirculated zone intensity, (b) increase of the spray Sauter mean diameter, (c) fuel staging, (d) oxidizer staging, and (e) ammonia injection. The present paper shows that NOx emission may be controlled without damage of the increase of incineration capacity by the enrichment and with low emission of partial oxidation pollutants such as CO.

Influence of Zn2+ co-doping ion on Eu3+-O2- associate luminescence in Sr2SiO4

This work reports on the study about the luminescence behavior of Eu3+-O2- associates in Sr2SiO4 doped with Eu3+, or simultaneously doped with Eu3+ and Zn2+ ions, where the Zn2+ doping ion acts as a charge compensating agent. Both Sr2SiO4:Eu3+ and Sr2SiO4:Eu3+,Zn2+ emission spectra show two types D-5(0)-->F-7(0) type transitions, one type related to Eu3+ in the Sr2+ Site, at 577 and 580 nm and the other one related to Eu3+-O2- associates, at 574 nm. Excitation spectra present two CT bands at 275 and 324 nm related to each emission center, respectively. Comparing the relative intensities between the emission spectra, the 0-->0 transition at 574 nm assigned to Eu3+-O2- associates in the Sr2SiO4:Eu3+ emission spectrum is much more intense than the same transition in the Sr2SiO4:Eu3+,Zn2+ emission spectrum. Moreover, in the Sr2SiO4:Eu3+ excitation spectrum, the intensity ratio between the CT band related to the Eu3+-O2- emission center and Eu3+ F-7-->L-5(6) transition is also larger than in the Sr2SiO4:Eu3+,Zn2+ one. Therefore, the presence of Zn2+ species provides an extra charge compensating mechanism, which decreases the formation of Eu3+-O2- associates. (C) 2002 Elsevier B.V. B.V. All rights reserved.

NOx and CO emissions and soot presence in partially premixed acoustically excited flames

The pulsating combustion process has attracted interest in current research because its application in energy generation can offer several advantages, such as fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with other new techniques of combustion. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides, and soot presence in partial premixed flames in confined partially premixed liquefied petroleum gas flames. The results basically showed that a more uniform fuel/air mixture due to the presence of an acoustic field increases the NOx emissions in operations close to stoichiometric equivalence ratios and the frequency is the most important parameter. Carbon monoxide and soot reduced significantly.

Lightning activity in Brazilian thunderstorms during TROCCINOX: implications for NOx production

During the TROCCINOX field experiment in January and February 2005, the contribution of lightning-induced nitrogen oxides (LNOx) from tropical and subtropical thunderstorms in Southern Brazil was investigated. Airborne trace gas measurements (NO, NOy, CO and O-3) were performed up to 12.5 km with the German research aircraft Falcon. During anvil penetrations in selected tropical and subtropical thunderstorms of 4 and 18 February, NOx mixing ratios were on average enhanced by 0.7-1.2 and 0.2-0.8 nmol mol(-1) totally, respectively. The relative contributions of boundary layer NOx (BL-NOx) and LNOx to anvil-NOx were derived from the NOx-CO correlations. on average similar to 80-90% of the anvil-NOx was attributed to LNOx. A Lightning Location Network (LINET) was set up to monitor the local distribution of cloud-to-ground (CG) and intra-cloud (IC) radiation sources (here called 'strokes') and compared with lightning data from the operational Brazilian network RINDAT (Rede Integrada Nacional de Deteccao de Descargas Atmosfericas). The horizontal LNOx mass flux out of the anvil was determined from the mean LNOx mixing ratio, the horizontal outflow velocity and the size of the vertical cross-section of the anvil, and related to the number of strokes contributing to LNOx. The values of these parameters were derived from the airborne measurements, from lightning and radar observations, and from a trajectory analysis. The amount of LNOx produced per LINET stroke depending on measured peak current was determined. The results were scaled up with the Lightning Imaging Sensor (LIS) flash rate (44 flashes s(-1)) to obtain an estimate of the global LNOx production rate. The final results gave similar to 1 and similar to 2-3 kg(N) per LIS flash based on measurements in three tropical and one subtropical Brazilian thunderstorms, respectively, suggesting that tropical flashes may be less productive than subtropical ones. The equivalent mean annual global LNOx nitrogen mass production rate was estimated to be 1.6 and 3.1 Tg a(-1), respectively. By use of LINET observations in Germany in July 2005, a comparison with the lightning activity in mid-latitude thunderstorms was also performed. In general, the same frequency distribution of stroke peak currents as for tropical thunderstorms over Brazil was found. The different LNOx production rates per stroke in tropical thunderstorms compared with subtropical and mid-latitude thunderstorms seem to be related to the different stroke lengths (inferred from comparison with laboratory data and observed lengths). In comparison, the impact of other lightning parameters as stroke peak current and stroke release height was assessed to be minor. The results from TROCCINOX suggest that the different vertical wind shear may be responsible for the different stroke lengths.

Sintering and mass transport features of (Sn,Ti)O2 polycrystalline ceramics

Different (Sn,Ti)O2 compositions were sintered at 1450 ��C for 2 h with the purpose of investigating their sintering and mass transport properties. Highly dense ceramics were obtained and their structural properties studied by X-ray diffraction and scanning electron microscopy. The changes in lattice parameters were analyzed by the Rietveld method and two mass transport mechanisms were observed during sintering in different temperature ranges, evidenced by the linear shrinkage rate as a function of temperature. The effect of the concentration of TiO2 on mass transport and densiffication during sintering was analyzed by considering the intrinsic defects. System densiffication was attributed to a mass transport mechanism in the SnO2 matrix, caused by the presence of TiO2, which formed a solid solution phase. The change in the mass transport mechanism was attributed to chemical bonding between SnO2 and TiO2, which improves ionic difusion as the concentration of TiO2 increased in (Sn,Ti)O2 compositions. �� 2002 Elsevier Science Ltd. All rights reserved.

Uso de m��todos qu��micos para obtener polvos cer��micos del sistema (Sn, Ti)O2

The (Sn,Ti)O2, system has a great interest due to its technological applications such as gas sensor and varistor. Although the thermodynamic properties and the kinetics of spinoidal decomposition in this system have been extensively studied, the general properties and applications of SnO2 - TiO2 binary compositions have been not investigated yet in depth. On the other hand, little work has been done to optimize the synthesis methods to obtain (Sn,Ti)O2 cerallmic powders, with pre - determinate physical and chemical characteristics. In this work the ceramic powders has been obtained by coprecipitation and polymeric precursor (Pechini) methods. The different physical chemistry phenomena that occurred during the synthesis were discussed. The (Sn,Ti)O2, ceramic powders were characterized with X- ray diffraction (XRD), thermal analysis (DTA/TG) and scanning electron microscopy (SEM). The knowledge about of steps and variables of synthesis process acquired with development of this work, we permited to obtain (Sn, Ti)O2, nanometers particles to low temperatures: to 450��C for coprecipitation method and to 600��C for Pechini method. The spinodal decomposition that ocurr to 900��C was discussed also.

Componente lento do V��O2 em crian��as durante exerc��cio pesado de corrida: An��lise com base em diferentes modelos matem��ticos

The purpose of this study was to identify and quantify the magnitude of the slow component of VO2 (SC) in children during running exercise, performed at heavy intensity domain (75%��), using two different mathematical models: a) three-exponential model and; b) ��VO2 6-3 min. Eight healthy male children (11.92 �� 0.63 years; 44.06 �� 13.01 kg; 146.63 �� 7.25 cm; and sexual maturity levels 1 and 2), not trained, performed in different days the following tests: 1) incremental running treadmill test to determine the peak oxygen uptake (VO2peak) and the lactate threshold (LT); and 2) two transitions from baseline to 75%�� [75%�� = LT + 0.75 x (VO2 peak - LT)] for six minutes on treadmill. The SC was determined by two models: a) three-exponential model (Exp3); and b) the VO2 difference between the sixth and the third exercise minute (��VO2 6-3min). The SC was expressed as the absolute (ml/min) and percent contribution (%) to the total change in VO 2. The SC values determined by model Exp3 (129.69 �� 75.71 ml/min and 8.4 �� 2.92%) and ��VO2 6-3 min (68.69 �� 102.54 ml/min and 3.6 �� 7.34%) were significantly different. So, the SC values in children during running exercise performed at heavy intensity domain (75%��) are dependent of the analysis model (Exp3 x ��VO2 6-3 min).

Study of utilization of petrol engine equipped with exhaust gas recirculation (EGR) and catalytic converter to reduce consumption and NOx emission

Study of consumption rate and gaseous pollutant emission from engine tests simulating real work conditions, using spark point manually controlled and exhaust gas recirculation (EGR) in diverse proportion levels. The objective of this work is to re-examine the potential of the EGR conception, a well-known method of combustion control, employed together electronic fuel injection and three-way catalytic converter closed-loop control at a spark ignition engine, verifying the performance characteristics and technical availability of this conception to improve pollution control, fuel economy at low torque drive condition and to improve the engine exhaust components useful life. The pollutant emissions and consumption levels under operational conditions simulations were analysed and compared with the expected by concerning theory and real tests performed by EGR equipped engines by factory. Copyright �� 2006 Society of Automotive Engineers, Inc.