Retrieval of kinetic rates in reactions with semi batch liquid phase using ill-posed inverse problem theory

A neural network procedure to solve inverse chemical kinetic problems is discussed in this work. Rate constants are calculated from the product concentration of an irreversible consecutive reaction: the hydrogenation of Citral molecule, a process with industrial interest. Simulated and experimental data are considered. Errors in the simulated data, up to 7% in the concentrations, were assumed to investigate the robustness of the inverse procedure. Also, the proposed method is compared with two common methods in nonlinear analysis; the Simplex and Levenberg-Marquardt approaches. In all situations investigated, the neural network approach was numerically stable and robust with respect to deviations in the initial conditions or experimental noises.

Flow-batch analyser for preparation of calibration standard mixtures in simultaneous multicomponent spectrometric analysis

The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simultaneous determination of several chemical species. However, when this methodology is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high operational cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu2+, Mn2+ and Zn2+ in polyvitaminic and polymineral pharmaceutical formulations, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the preparation of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples h-1 can be carried out with the proposed flow-batch analyser.

CONJUGAÇÃO DOS MÉTODOS DA MATRIZ DE INTERAÇÃO E DO CHECK-LIST NA AVALIAÇÃO QUALI-QUANTITATIVA DE IMPACTOS AMBIENTAIS DE UM PROGRAMA DE FOMENTO FLORESTAL

RESUMOEste estudo teve como objetivo principal avaliar, qualitativa e quantitativamente, os impactos ambientais de um programa de fomento florestal, por meio do método da matriz de interação, coadjuvado por uma lista de verificação complementar, conhecida como método do check-list. Verificou-se, também, a aplicabilidade e complementaridade desses métodos para este caso. O referido programa foi realizado na região de influência do Polo Moveleiro de Ubá, na Zona da Mata mineira. O método da matriz de interação identificou 473 impactos, sendo 172 positivos (36,4%) e 301 negativos (63,6%), enquanto o método do check-list identificou 94 impactos, sendo 34 positivos (36,2%) e 60 negativos (63,8%). Concluiu-se que o referido programa possui impactos ambientais negativos e positivos, numa proporção de cerca de dois para um, respectivamente, bem como que os métodos usados se mostraram eficientes para a situação verificada, uma vez que foram capazes de identificar e descrever, em plenitude, tais impactos ambientais e de forma complementar.

Quali/quantitative characterization of biogas produced in batch digesters supplied with six distinct substrates

The present research was carried out at the DER/FCAV, São Paulo State University - Brazil, with the purpose of analyzing the quantity and quality of biogas produced by six types of substrates. The substrates used in the anaerobic digestion were characterized as: 1- Litter of broiler (LB); 2- Grinded broiler litter (GBL); 3- Broiler litter with wood shavings (BLWS); 4- Grinded broiler litter with wood shavings (GBLWS); 5- Broiler litter with peanut hulls (BLPH); 6- Grinded broiler litter with peanut hull (GBLPH). It was concluded from the collected data that: the (GBL) substrate showed a superior biogas accumulated production in relation to the other substrates, while the BLWS presented an inferior accumulated production; the grinded substrates showed higher quantities of accumulated biogas in relation to the non-grinded substrates, except for GBLPH, with 20.9 m³ inferior than BLPH; the period of maximum biogas production started from 45 to 60 days, declining after 120 days; at 57 days after filling up the digesters the biogas produced had levels of CH4 superior than 53%, and from 99 days all of them produced biogas with levels of CH4 superior than 70%; LB and GBL presented higher concentrations of CH4 in the biogas.

Kinetic behavior of nitrification in the post-treatment of poultry wastewater in a sequential batch reactor

A sequential batch reactor with suspended biomass and useful volume of 5 L was used in the removal of nutrients and organic matter in workbench scale under optimal conditions obtained by central composite rotational design (CCRD), with cycle time (CT) of 16 h (10.15 h, aerobic phase, and 4.35 h, anoxic phase) and carbon: nitrogen ratio (COD/NO2--N+NO3--N) equal to 6. Complete cycles (20), nitrification followed by denitrification, were evaluated to investigate the kinetic behavior of degradation of organic (COD) and nitrogenated (NH4+-N, NO2--N and NO3--N) matter present in the effluent from a bird slaughterhouse and industrial processing facility, as well as to evaluate the stability of the reactor using Shewhart control charts of individual measures. The results indicate means total inorganic nitrogen (NH4+-N+NO2- -N+NO3--N) removal of 84.32±1.59% and organic matter (COD) of 53.65±8.48% in the complete process (nitrification-denitrification) with the process under statistical control. The nitrifying activity during the aerobic phase estimated from the determination of the kinetic parameters had mean K1 and K2 values of 0.00381±0.00043 min-1 and 0.00381±0.00043 min-1, respectively. The evaluation of the kinetic behavior of the conversion of nitrogen indicated a possible reduction of CT in the anoxic phase, since removals of NO2--N and NO3--N higher than 90% were obtained with only 1 h of denitrification.

Performance of UASB reactors in two stages followed by post-treatment with activated sludge in wastewater batch of wet-processed coffee

In this study it was evaluated the efficiency of the treatment of wet-processed coffee wastewater in upflow anaerobic sludge blanket (UASB) reactors in two stages, in bench scale, followed by post-treatment with activated sludge in batch. The first UASB reactor was submitted to an hydraulic retention time (HRT) of 6.2 d and organic loading rates (OLR) of 2.3 and 4.5g CODtotal (L d)-1, and the second UASB reactor to HRT of 3.1 d with OLR of 0.4 and 1.4g CODtotal (L d)-1. The average values of the affluent CODtotal increased from 13,891 to 27,926mg L-1 and the average efficiencies of removal of the CODtotal decreased from 95 to 91%, respectively, in the UASB reactors in two stages. The volumetric methane production increased from 0.274 to 0.323L CH4 (L reactor d)-1 with increment in the OLR. The average concentrations of total phenols in the affluent were of 48 and 163mg L-1, and the removal efficiencies in the UASB reactors in two stages of 92 and 90%, respectively, and increased to 97% with post-treatment. The average values of the removal efficiencies of total nitrogen and phosphorus were of 57 to 80% and 44 to 60%, respectively, in the UASB reactors in two stages and increased to 91 and 84% with the post-treatment.

Anaerobic-aerobic treatment of swine wastewater in uasb and batch reactors in series

In this work it was evaluated the performance of two systems of swine wastewater treatment consisting of two-stage upflow anaerobic sludge blanket (UASB) reactors, with and without post-treatment in sequencing batch reactor (SBR), fed continuously, with aerobic phase. The UASB reactors in the first stage had 908 L in the sets I and II, and in the second stage 350 and 188 L, respectively. In the set II the post-treatment was performed in a SBR of 3,000 L. The hydraulic detention times in the anaerobic treatment systems were 100, 75 and 58 h in the set I; 87, 65 and 51 h in the set II; and 240 and 180 h in the SBR. The volumetric organic load applied in the first stage UASB reactors ranged from 6.9 to 12.6 g total COD (L d)-1 in the set I and 7.5 to 9.8 g total COD (L d)-1 in the set II. The average removal efficiencies of total COD, total phosphorus (Ptotal), and Kjeldahl and organic nitrogen (KN and Norg) in the anaerobic treatment systems were similar and reached maximum values of 97%, 64%, 68%, and 98%. In the SBR, the removal efficiencies of total COD and thermotolerant coliforms were up to 62 and 92% resulting, respectively, in effluent concentrations of 135 mg L-1 and 2x10(4)MPN (100 mL)-1. For Ptotal, total nitrogen (TN) and Norg, the average removal efficiencies in the SBR were up to 58, 25 and 73%, respectively.

Application of response surface methodology to study the biological removal of nitrogen from effluent of cattle slaughterhouse in a sequencing batch reactor

The aim of this study was to evaluate the efficiency of a sequencing batch reactor (SBR) on biological removal of nitrogen from cattle slaughterhouse wastewater by nitrification/denitrification processes. The effects of initial concentration of ammoniacal nitrogen were investigated at 100; 150 and 200 mg L-1 and air flow rate at 0.125; 0.375 and 0.625 L min¹ Lreactor-1 on the nitrogen compounds removal, by a Central Composite Rotational Design (CCRD) configuration. There were variations from 9.2 to 94.9%, 4.0 to 19.6% and 20.8 to 92.0% in the conversion of ammoniacal nitrogen to nitrate and nitrite concentration and removal of total nitrogen, respectively. The increase of air flow rate and decrease of the initial concentration of ammoniacal nitrogen resulted in higher efficiencies of total nitrogen removal, as well as the conversion of ammoniacal nitrogen to nitrate. During the pre-established intervals of this study, the removal and conversion efficiencies of nitrogen compounds above 85% were achieved in air flow rate variations from 0.375 to 0.725 L min-1 Lreactor-1 and initial concentration of ammoniacal nitrogen from 80 to 200 mg L-1. On denitrification process, we obtained efficiencies from 91.5 to 96.9% on the removal of nitrite/nitrate and from 78.3 to 87.9% on the removal of organic matter.

Effect of cycle time and airflow in biological nitrogen removal from poultry slaughterhouse wastewater using sequencing batch reactor

This study aimed to evaluate the influence of airflow (0.25, 0.50 and 0.75 L.L-1.min-1) and cycle time (10.45 h, 14.25 h and 17.35 h) on a sequencing batch reactor (SBR) performance in promoting nitrification and denitrification of poultry slaughterhouse wastewater. The operational stages included feeding, aerobic and anoxic reactions, sedimentation and discharge. SBR was operated in a laboratory scale with a working volume of 4 L, keeping 25% of biomass retained inside the reactor as inoculum for the next batch. In the anoxic stage, C: N ratio was maintained between 5 and 6 by adding cassava starch wastewater. A factorial design (22) with five repetitions was designed at the central point to evaluate the influence of cycle time and airflow on total inorganic nitrogen removal (N-NH4++N-NO2-+N-NO3-) and in the whole process (nitrification and denitrification). The highest total inorganic nitrogen removal (93.3%) was observed for airflow of 0.25 L.L-1.min‑1 and a cycle time of 14.25 h. At the end of the experiment, the sludge inside the reactor was characterized by fluorescent in situ hybridization (FISH), indicating the presence of ammonia and nitrite oxidizing bacteria.

Reliability and validity of the interactive observation scale for psychiatric inpatients applied by nursing aides in daily ward practice

The main characteristic of the nursing Interactive Observation Scale for Psychiatric Inpatients (IOSPI) is the necessity of interaction between raters and patients during assessment. The aim of this study was to evaluate the reliability and validity of the scale in the "real" world of daily ward practice and to determine whether the IOSPI can increase the interaction time between raters and patients and influence the raters' opinion about mental illness. All inpatients of a general university hospital psychiatric ward were assessed daily over a period of two months by 9 nursing aides during the morning and afternoon shifts, with 273 pairs of daily observations. Once a week the patients were interviewed by a psychiatrist who filled in the Brief Psychiatric Rating Scale (BPRS). The IOSPI total score was found to show significant test-retest reliability (interclass correlation coefficient = 0.83) and significant correlation with the BPRS total score (r = 0.69), meeting the criteria of concurrent validity. The instrument can also discriminate between patients in need of further inpatient treatment from those about to be discharged (negative predictive value for discharge = 0.91). Using this scale, the interaction time between nursing aides and patients increased significantly (t = 2.93, P<0.05) and their opinion about the mental illness changed. The "social restrictiveness" factor of the opinion scale about mental illness showed a significant reduction (t = 4.27, P<0.01) and the "interpersonal etiology" factor tended to increase (t = 1.98, P = 0.08). The IOSPI was confirmed as a reliable and valid scale and as an efficient tool to stimulate the therapeutic attitudes of the nursing staff.

Comparison of the homeostasis model assessment and quantitative insulin sensitivity check index with data from forearm metabolic studies for the in vivo assessment of insulin sensitivity

The present study was designed to compare the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI) with data from forearm metabolic studies of healthy individuals and of subjects in various pathological states. Fifty-five healthy individuals and 112 patients in various pathological states, including type 2 diabetes mellitus, essential hypertension and others, were studied after an overnight fast and for 3 h after ingestion of 75 g of glucose, by HOMA, QUICKI and the forearm technique to estimate muscle uptake of glucose combined with indirect calorimetry (oxidative and non-oxidative glucose metabolism). The patients showed increased HOMA (1.88 ± 0.14 vs 1.13 ± 0.10 pmol/l x mmol/l) and insulin/glucose (I/G) index (1.058.9 ± 340.9 vs 518.6 ± 70.7 pmol/l x (mg/100 ml forearm)-1), and decreased QUICKI (0.36 ± 0.004 vs 0.39 ± 0.006 (µU/ml + mg/dl)-1) compared with the healthy individuals. Analysis of the data for the group as a whole (patients and healthy individuals) showed that the estimate of insulin resistance by HOMA was correlated with data obtained in the forearm metabolic studies (glucose uptake: r = -0.16, P = 0.04; non-oxidative glucose metabolism: r = -0.20. P = 0.01, and I/G index: r = 0.17, P = 0.03). The comparison of QUICKI with data of the forearm metabolic studies showed significant correlation between QUICKI and non-oxidative glucose metabolism (r = 0.17, P = 0.03) or I/G index (r = -0.37, P < 0.0001). The HOMA and QUICKI are good estimates of insulin sensitivity as data derived from forearm metabolic studies involving direct measurements of insulin action on muscle glucose metabolism.

Effect of the aerobic capacity on the validity of the anaerobic threshold for determination of the maximal lactate steady state in cycling

The maximal lactate steady state (MLSS) is the highest blood lactate concentration that can be identified as maintaining a steady state during a prolonged submaximal constant workload. The objective of the present study was to analyze the influence of the aerobic capacity on the validity of anaerobic threshold (AT) to estimate the exercise intensity at MLSS (MLSS intensity) during cycling. Ten untrained males (UC) and 9 male endurance cyclists (EC) matched for age, weight and height performed one incremental maximal load test to determine AT and two to four 30-min constant submaximal load tests on a mechanically braked cycle ergometer to determine MLSS and MLSS intensity. AT was determined as the intensity corresponding to 3.5 mM blood lactate. MLSS intensity was defined as the highest workload at which blood lactate concentration did not increase by more than 1 mM between minutes 10 and 30 of the constant workload. MLSS intensity (EC = 282.1 ± 23.8 W; UC = 180.2 ± 24.5 W) and AT (EC = 274.8 ± 24.9 W; UC = 187.2 ± 28.0 W) were significantly higher in trained group. However, there was no significant difference in MLSS between EC (5.0 ± 1.2 mM) and UC (4.9 ± 1.7 mM). The MLSS intensity and AT were not different and significantly correlated in both groups (EC: r = 0.77; UC: r = 0.81). We conclude that MLSS and the validity of AT to estimate MLSS intensity during cycling, analyzed in a cross-sectional design (trained x sedentary), do not depend on the aerobic capacity.

Reliability and validity of a Portuguese version of the Young Mania Rating Scale

The reliability and validity of a Portuguese version of the Young Mania Rating Scale were evaluated. The original scale was translated into and adapted to Portuguese by the authors. Definitions of clinical manifestations, a semi-structured anchored interview and more explicit rating criteria were added to the scale. Fifty-five adult subjects, aged 18 to 60 years, with a diagnosis of Current Manic Episode according to DSM-III-R criteria were assessed using the Young Mania Rating Scale as well as the Brief Psychiatric Rating Scale in two sessions held at intervals from 7 to 10 days. Good reliability ratings were obtained, with intra-class correlation coefficient of 0.97 for total scores, and levels of agreement above 0.80 (P < 0.001) for all individual items. Internal consistency analysis resulted in an alpha = 0.67 for the scale as a whole, and an alpha = 0.72 for each standardized item (P < 0.001). For the concurrent validity, a correlation of 0.78 was obtained by the Pearson coefficient between the total scores of the Young Mania Rating Scale and Brief Psychiatric Rating Scale. The results are similar to those reported for the English version, indicating that the Portuguese version of the scale constitutes a reliable and valid instrument for the assessment of manic patients.

The validity and 4-year test-retest reliability of the Brazilian version of the Eating Attitudes Test-26

In a cross-sectional study conducted four years ago to assess the validity of the Brazilian version of the Eating Attitudes Test-26 (EAT-26) for the identification of abnormal eating behaviors in a population of young females in Southern Brazil, 56 women presented abnormal eating behavior as indicated by the EAT-26 and the Edinburgh Bulimic Investigation Test. They were each matched for age and neighborhood to two normal controls (N = 112) and were re-assessed four years later with the two screening questionnaires plus the Composite International Diagnostic Interview (CIDI). The EAT results were then compared to diagnoses originating from the CIDI. To evaluate the temporal stability of the two screening questionnaires, a test-retest design was applied to estimate kappa coefficients for individual items. Given the prevalence of eating disorders of 6.2%, the CIDI psychiatry interview was applied to 161 women. Of these, 0.6% exhibited anorexia nervosa and 5.6%, bulimia nervosa (10 positive cases). The validity coefficients of the EAT were: 40% sensitivity, 84% specificity, and 14% positive predictive value. Cronbach's coefficient was 0.75. For each EAT item, the kappa index was not higher than 0.344 and the correlation coefficient was lower than 0.488. We conclude that the EAT-26 exhibited low validity coefficients for sensitivity and positive predictive value, and showed a poor temporal stability. It is reasonable to assume that these results were not influenced by the low prevalence of eating disorders in the community. Thus, the results cast doubts on the ability of the EAT-26 test to identify cases of abnormal eating behaviors in this population.