Length of stay in a neonatal intensive care unit and its association with low rates of exclusive breastfeeding in very low birth weight infants

OBJECTIVE: To identify the inpatient maternal and neonatal factors associated to the weaning of very low birth weight (VLBW) infants. METHODS: One hundred nineteen VLBW (<1500 g) infants were monitored from July 2005 through August 2006, from birth to the first ambulatory visit after maternity discharge. This maternity unit uses the Kangaroo Method and the Baby Friendly Hospital Initiative. Out of 119 VLBW infants monitored until discharge, 88 (75%) returned to the facility, 22 (25%) were on exclusive breastfeeding (EB), and 66 (75%) were weaned (partial breastfeeding or formula feeding). RESULTS: Univariate analysis found an association between weaning and lower birth weight, longer stays in the neonatal intensive care unit (NICU), and longer hospitalization times, in addition to more prolonged enteral feeding and birth weight recovery period. Logistic regression showed length of NICU stay as being the main determinant of weaning. CONCLUSION: The negative repercussion on EB of an extended stay in the NICU is a significant challenge for health professionals to provide more adequate nutrition to VLBW infants.

Length of stay in a neonatal intensive care unit and its association with low rates of exclusive breastfeeding in very low birth weight infants

OBJECTIVE: To identify the inpatient maternal and neonatal factors associated to the weaning of very low birth weight (VLBW) infants. METHODS: One hundred nineteen VLBW (<1500 g) infants were monitored from July 2005 through August 2006, from birth to the first ambulatory visit after maternity discharge. This maternity unit uses the Kangaroo Method and the Baby Friendly Hospital Initiative. Out of 119 VLBW infants monitored until discharge, 88 (75%) returned to the facility, 22 (25%) were on exclusive breastfeeding (EB), and 66 (75%) were weaned (partial breastfeeding or formula feeding). RESULTS: Univariate analysis found an association between weaning and lower birth weight, longer stays in the neonatal intensive care unit (NICU), and longer hospitalization times, in addition to more prolonged enteral feeding and birth weight recovery period. Logistic regression showed length of NICU stay as being the main determinant of weaning. CONCLUSION: The negative repercussion on EB of an extended stay in the NICU is a significant challenge for health professionals to provide more adequate nutrition to VLBW infants.

Avaliação do ganho de peso de bebês prematuros em relação ao leite materno cru e leite pasteurizado

This study aims to evaluate the weight gain of premature newborns fed with breast milk from their mothers' from those that are fed with breast milk from the milk bank. The research is the quantitative, descriptive and observational kind. It was conducted in the Neonatal Intensive Care Unit and Housing from the Maternity Hospital Escola Januário Cicco (MEJC), that is a reference for high risk pregnancy and birth in Rio Grande do Norte. The premature newborns included were following these parameters: gestational age from 26 to 37 weeks, initially hospitalized at UTIN, with oral diet, by means by gavage, cup and/or suction. Studies with premature newborns with a zero diet longer than seven days or complications that interfered in the evaluation of weight gain were excluded from this study. The sample was selected for convenience and had data of all newborns hospitalized at UTIN from the May to June of 2014 time period, followed to their discharge, ended by August of 2014 and had the inclusion parameters of the study. From the period of the data collection, 60 premature newborns entered the maternity and 39 of those were the sample of research. The project was approved by the Research Ethics Committee from UFRN, under CAAE nº 0699.0.000.294-11. The data was analyzed by means of descriptive and deduced statistics. The results indicated that the involved in the study, were born from mother with average age of 25,36 years, with less than nine years education 21 (53,8%), had the family income less than a minimum wage 24 (61,5%). Among the newborn, the female gender predominated 20 (51,3%), had cesarean delivery 25 (64,1%), had moderate prematurity 29 (74,5%), more of 1.500g 22 (556,4%). The birth weight average was 1.608,49g. The total of diets were 9.994, and an average of 256 for each newborn, in a 32,12 days of hospitalization time period. Most of the diet supplies were from the breast milk bank (50,34%), however 56,4% of the newborns had most of the diet from their mothers' milked breast milk. It was detected that 38,5% of the newborns had, in some given moment, artificial milk. The daily weight gain average of all newborns was 2,59g, but 35% of them had an average above 10g per day. From the newborn's group (n=25) that had medium weight gain, only 9 of them (36,0%) received mainly their own mothers' milked breast milk. It's been conclusive that most of the premature newborns gained weight predominantly from diets from the breast milk of the Milk Bank, showing the need of a bigger incentive to exclusive breast feeding.

Segurança do paciente em terapia intensiva neonatal: identificação e análise de eventos adversos

The patient safety is a major concern in health services for its global dimension, as evidenced by the fragility of care processes that predispose an occurrence of adverse events. These events in a neonatal intensive care unit are considered serious and hazardous to lives of newborns. The present study aimed to identify and analyze adverse events in a neonatal intensive care unit based in Trigger Tool. It is an epidemiological, cross-sectional , exploratory, retrospective study with quantitative, descriptive and analytical approach, performed in 2015 at a school hospital. The sample was not probabilistic, involving 116 newborns who met the eligibility criteria. Data collection was performed by retrospective review of medical records, using a specific kind of "trigger" instrument, composed of sentinel events in neonatology, adapted from the American model used by the Vermont-Oxford Network. Data were analyzed using descriptive and inferential statistics. The chi-square test for linear trend was used to assess the associations between the variables of interest. The research received a favorable agreement from Ethics Committee of the Federal University of Rio Grande do Norte, under number 1055533, and Presentation Certificate for Ethics Assessment 43894515.6.0000.5537. The results show among investigated newborns, 110 experienced at least one adverse event during their stay, with a total of 391 medical records analyzed and rate of 3.37 events per patient. Prevailed the preterm newborns with low birth weight, from mother who had hypertensive diseases during pregnancy and urinary tract infection. The average hospitalization time was 25 days, associated with hospital-acquired infections events (p = 0.01). Among the identified adverse events stood out the events related to thermoregulation disorders (39.0%), with prevalence of hypothermia (26.0%), followed by health care-related infections (16.4%) and blood glucose disorders, hypoglycemia (9.00%) and hyperglycemia (6.64%). Most of these incidents were classified in categories E and F, which represents that there was damage small proportion. Due to these damages come from the care practice with newborn, 78% were classified as avoidable. There was statistically significant association between the variable birth weight with infections (p = 0.006) as well as peri/intraventricular bleeding (p = 0.02), hypoglycemia (p = 0.021), hyperglycemia (p = 0.001), hyperthermia (p = 0.39) and death (p=0,02). Gestational age was associated with seizures (p = 0.002), hyperglycemia (p=0.017) e hyperthermia (p=0.027). The security institution culture was reported by the health workers as intermediate, even though the number of adverse events found in only one unit of service indicates that there is much to be done. Thus the high rate of adverse events identified in the neonatal intensive care unit reinforces the necessity to elaborate specific preventive strategies for this risk environment.

Segurança do paciente em terapia intensiva neonatal: identificação e análise de eventos adversos

The patient safety is a major concern in health services for its global dimension, as evidenced by the fragility of care processes that predispose an occurrence of adverse events. These events in a neonatal intensive care unit are considered serious and hazardous to lives of newborns. The present study aimed to identify and analyze adverse events in a neonatal intensive care unit based in Trigger Tool. It is an epidemiological, cross-sectional , exploratory, retrospective study with quantitative, descriptive and analytical approach, performed in 2015 at a school hospital. The sample was not probabilistic, involving 116 newborns who met the eligibility criteria. Data collection was performed by retrospective review of medical records, using a specific kind of "trigger" instrument, composed of sentinel events in neonatology, adapted from the American model used by the Vermont-Oxford Network. Data were analyzed using descriptive and inferential statistics. The chi-square test for linear trend was used to assess the associations between the variables of interest. The research received a favorable agreement from Ethics Committee of the Federal University of Rio Grande do Norte, under number 1055533, and Presentation Certificate for Ethics Assessment 43894515.6.0000.5537. The results show among investigated newborns, 110 experienced at least one adverse event during their stay, with a total of 391 medical records analyzed and rate of 3.37 events per patient. Prevailed the preterm newborns with low birth weight, from mother who had hypertensive diseases during pregnancy and urinary tract infection. The average hospitalization time was 25 days, associated with hospital-acquired infections events (p = 0.01). Among the identified adverse events stood out the events related to thermoregulation disorders (39.0%), with prevalence of hypothermia (26.0%), followed by health care-related infections (16.4%) and blood glucose disorders, hypoglycemia (9.00%) and hyperglycemia (6.64%). Most of these incidents were classified in categories E and F, which represents that there was damage small proportion. Due to these damages come from the care practice with newborn, 78% were classified as avoidable. There was statistically significant association between the variable birth weight with infections (p = 0.006) as well as peri/intraventricular bleeding (p = 0.02), hypoglycemia (p = 0.021), hyperglycemia (p = 0.001), hyperthermia (p = 0.39) and death (p=0,02). Gestational age was associated with seizures (p = 0.002), hyperglycemia (p=0.017) e hyperthermia (p=0.027). The security institution culture was reported by the health workers as intermediate, even though the number of adverse events found in only one unit of service indicates that there is much to be done. Thus the high rate of adverse events identified in the neonatal intensive care unit reinforces the necessity to elaborate specific preventive strategies for this risk environment.

A desigualdade espacial do Baixo Peso ao Nascer no Brasil

Low birth weight (LBW) is a risk factor for neonatal and infant morbidity and mortality. In Brazil the highest percentages of low birth weight occur in regions of higher socio-economic status. The scope of this article is to ascertain the spatial distribution of low birth weight rates and the correlation with social and service indicators. The scale is ecological taking all the Brazilian states as units of analysis. The spatial analysis technique is the methodology used together with data from SINASC, IPEA and IBGE for 2009. Higher rates of low birth weight are found in the south/southeastern states (Global Moran: 0.267, p = 0.02). Clusters of the high-high type in the Southeast and of the low-low variety in states in the Amazon region are detected. The spatial inequality of low birth weight reflects the socio-economic conditions of the states. More developed regions have higher rates of low birth weight, therefore, the presence of the service and its use decrease infant mortality and increase LBW.

Produção e caracterização de quitooligossacarídeos produzidos pelo fungo Metarhizium anisopliae e avaliação da citotoxicidade em células tumorais

Chitosan is a natural polymer, biodegradable, nontoxic, high molecular weight derived from marine animals, insects and microorganisms. Oligomers of glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) have interesting biological activities, including antitumor effects, antimicrobial activity, antioxidant and others. The alternative proposed by this work was to study the viability of producing chitooligosaccharides using a crude enzymes extract produced by the fungus Metarhizium anisopliae. Hydrolysis of chitosan was carried out at different times, from 10 to 60 minutes to produce chitooligosaccharides with detection and quantification performed by High Performace Liquid Chromatography (HPLC). The evaluation of cytotoxicity of chitosan oligomers was carried out in tumor cells (HepG2 and HeLa) and non-tumor (3T3). The cells were treated for 72 hours with the oligomers and cell viability investigated using the method of MTT. The production of chitosan oligomers was higher for 10 minutes of hydrolysis, with pentamers concentration of 0.15 mg/mL, but the hexamers, the molecules showing greater interest in biological properties, were observed only with 30 minutes of hydrolysis with a concentration of 0.004 mg/mL. A study to evaluate the biological activities of COS including cytotoxicity in tumor and normal cells and various tests in vitro antioxidant activity of pure chitosan oligomers and the mixture of oligomers produced by the crude enzyme was performed. Moreover, the compound with the highest cytotoxicity among the oligomers was pure glucosamine, with IC50 values of 0.30; 0.49; 0.44 mg/mL for HepG2 cells, HeLa and 3T3, respectively. Superoxide anion scavenging was the mainly antioxidant activity showed by the COS and oligomers. This activity was also depending on the oligomer composition in the chitosan hydrolysates. The oligomers produced by hydrolysis for 20 minutes was analyzed for the ability to inhibit tumor cells showing inhibition of proliferation only in HeLa cells, did not show any effect in HepG2 cells and fibroblast cells (3T3)

Desmame em recém-nascidos de muito baixo peso ao nascer no primeiro retorno ambulatorial após a alta hospitalar

Investigate intrahospital and neonatal determinants associated to the weaning of very low birth weight (VLBW) infants. Methods: 119 VLBW (<1500g) infants 81 were monitored from July 2005 through August 2006, from birth to the first ambulatory visit after maternity discharge. This maternity unit uses the Kangaroo Method and the Baby Friendly Hospital Initiative. Results: Out of 119 VLBW infants monitored until discharge, 88 (75%) returned to the facility, 22 (25%) were on exclusive breastfeeding (EB) and 66 (75%) were weaned (partial breastfeeding or formula feeding). Univariate analysis found an association between weaning and lower birth weight, longer stays in the NICU and longer hospitalization times, in addition to more prolonged enteral feeding and birth weight recovery period. Logistic regression showed length of NICU stay as being the main determinant of weaning. Conclusion: The negative repercussion on EB of an extended stay in the NICU is a significant challenge for health professionals to provide more adequate nutrition to VLBW infants

Associação entre fatores nutricionais e a resposta frente à infecção por Leishmania chagasi

Leishmania chagasi infection presents a wide spectrum of clinical outcomes, ranging from asymptomatic self resolving infection to disease, visceral leishmaniasis (VL). The exact mechanisms that lead the evolution of infection to disease are not understood. It is believed that malnutrition is a risk factor associated with VL development, although there are few human studies in the area. We aimed to assess the nutritional factors associated with the response to L. chagasi infection in Rio Grande do Norte. The study was conducted from December 2006 to January 2008. 149 children were assessed: 20 active VL cases, 33 children with VL history, 40 DTH+ asymptomatic children and 56 DTH-. Nutritional status was assessed using z scores for Weight/Age, Weight/Height, Height/Age, Body Mass Index (BMI), and mid-upper arm circumference/height (MUAC/height). Vitamin A status was determined by serum retinol concentrations and the modified-relative-dose-esponse test (MRDR). Breastfeeding time and birth weight were also evaluated. VL children presented compromised nutritional status when compared to the other groups using BMI and MUAC/age, with means -1,53 ± 1,10 and -1,48 ± 1,28 z scores, respectively (ANOVA, p < 0,05). VL children also showed lower vitamin A levels: 43% presented serum retinol < 20 µg/dL and 15% MRDR > 0,060. Birth weight was inverserly associated with the risk to belong the VL group (β = -0,00; OR = 0,84; 95% CI 0,73 - 0,99; p = 0,047), whereas more breastfeeding time was directly associated with the risk to belong to the DTH+ group (β = 0,02; OD = 1,16; 95% CI 1,01 - 1,33; p = 0,036). The nutritional variables evaluated were associated with the response to the L. chagasi infection, with malnutrition and compromised vitamin A status as markers of children who present with VL. Higher birth weight was associated with protection to disease, and higher breastfeeding time was associated with increased likelihood of an asymptomatic infection. The results show that modifiable nutritional aspects in the study population are associated with the response to the L. chagasi infection

Extração, caracterização e atividades biológicas de proteínas da espécie cnidoscolus urens (L.) Arthur

The extraction, chemical and structural characterization of a wide variety of compounds derived from plants has been a major source of bioactive molecules. Several proteases have been isolated in the plant kingdom, with numerous pharmacological and biotechnological applications. Among the proteases isolated from plants, are the fibrinogenolytic, with relevant application in the treatment of disorders in the coagulation cascade, in addition to potential use as a tool in clinical laboratories. In this study, in addition to evaluating the effects of the protein extract of Cnidoscolus urens (L.) Arthur (Euphorbiaceae) in the coagulation cascade also investigates the presence of antimicrobial activity and characterizes the proteolytic activity detected in this extract, aiming to determine their potential pharmacological and biotechnological application. In this way, crude protein extracts obtained from the leaves of C. urens in Tris-HCl 0.05M, NaCl 0.15M, pH 7.5, were precipitated in different concentrations of acetone, and assessed for the presence of proteolytic activity in azocaseína and fibrinogen. The most active fraction (F1.0) in these tests was chosen for assessment of biological activity and biochemical characterization. The Aα chain and Bβ of fibrinogen were completely cleaved at a concentration of 0.18 μg/μL of protein fraction in 4 minutes. Fibrinogenolytic activity presented total inhibition in the presence of E-64 and partial in the presence of EDTA. The fraction demonstrated coagulant activity in plasm and reduced the APTT, demonstrating acting on the factors coagulation of the intrinsic pathway and common, not exerting effects on the PT. Fibrinolytic activity on plasma clot was detected only in SDS-PAGE in high concentrations of fraction, and there were no defibrinating. Although several proteases isolated from plants and venomous animals are classically toxic, the fraction F1.0 of C. urens not expressed hemorrhagic nor hemolytic activities. Fraction F1.0 also showed no antimicrobial activity. In proteolytic activity on the azocasein, the optimal pH was 5.0 and optimum temperature of 60ºC. The enzyme activity has been shown to be sensitive to the presence of salts tested, with inhibition for all compounds. The surfactant triton did not influence the enzyme activity, but the tween-20 and SDS inhibited the activity. In the presence of reducing agents increase in enzyme activity occurred, a typical feature of enzymes belonging to the class of cysteine proteases. Several bands with proteolytic activity were detected in zymogram, in the region of high-molecular-weight, which were inhibited by E-64. In this study, we found that C. urens presents in its constitution cysteine proteases with fibrinogenolytic and procoagulant activity, which may be isolated, with potential application in treatment of bleeding disorders, thrombolytic and clinical laboratory

Estudo da cristalização de parafinas em sistemas solventes/tensoativos/água

The WAT is the temperature at the beginning of the appearance of wax crystals. At this temperature the first wax crystals are formed by the cooling systems paraffin / solvents. Paraffins are composed of a mixture of saturated hydrocarbons of high molecular weight. The removal of petroleum from wells and the production lines means a surcharge on produced oil, thus solubilize these deposits formed due to modifications of thermodynamics has been a constant challenge for companies of oil exploration. This study combines the paraffin solubilization by microemulsion systems, the determination of WAT systems paraffin / solvent and performance of surfactant in reducing the crystallization. We used the methods: rheological and the photoelectric signal, validating the latter which was developed to optimize the data obtained due to sensitivity of the equipment used. Methods developed for description of wax precipitation are often in poor agreement with the experimental data, they tend to underestimate the amount of wax at temperatures below the turbidity point. The Won method and the Ideal solution method were applied to the WAT data obtained in solvent systems, best represented by the second interaction of Won method using the solvents naphtha, hexane and LCO. It was observed that the results obtained by WAT photoelectric signal when compared with the viscosity occur in advance, demonstrating the greatest sensitivity of the method developed. The ionic surfactant reduced the viscosity of the solvent systems as it acted modifying the crystalline structure and, consequently, the pour point. The curves show that the WAT experimental data is, in general, closer to the modeling performed by the method of Won than to the one performed by the ideal solution method, because this method underestimates the curve predicting the onset of paraffin hydrocarbons crystallization temperature. This occurs because the actual temperature measured was the crystallization temperature and the method proposes the fusion temperature measurement.

Eficácia do bochecho de quitosana a 0,4% sobre o biofilme e bactérias orais

The purpose of this study was evaluate the effectiveness of the chitosan at 0.4 with high molecular weight and high deacetylation degree mouthrinse over the total decrease of the streptococci, Streptococcus mutans, lactobaci/li and over the perceptible bacterial film and gingival bleeding indices. For that, a total of 68 healthy students between 11 and 13 years old, not allergic to crustacean and not users of antibiotics or antimicrobial agent for the last three months or during the treatment, was selected. From those, thirty two individuaIs used the mouthrinse test, and thirty six, the control one. The participants rinsed 10 mL of the solutions twice a day, one during the moming (which was supervised), and another one during the aftemoon (which was not supervised), for fifteen days. The saliva collect for the microbiological analysis, as well as the perceptible bacterial film and gingival bleeding indices check, were made before the use ofthe mouthrinses (base line), immediately after the last mouthrinse on the day (zero time) and fifteen days after (fifteen time). These data were collected at school and the saliva was carried inside the ice to the laboratory. The samples were diluted, and 0.1 mL ofthe 10 -1 dilution was seeded in Rogosa SL agar, for further analysis of the total of lactobaci/lus~ 0.1 mL of the 10-4 dilution in Mitis Salivarius with bacitracin, for S. mutans analysis; and 0.1 mL of the 10-6 dilution in Mitis Salivarius for the analysis ofthe total of streptococcus. The Rogosa SL agar plates were incubated in aerobic at 37°C for 72 hours and the MSB and the MS were incubated in anaerobic in Gaspak@ jars at 37°C for 48 hours for further count ofColonies Former Units (CFUs). The assay was made in duplicate for each bacterial group analyzed. The number of CFUs transformed in LOGlO was analyzed according to the following tests: ANOV A, t of Paired and Not Paired Student, Friedman, Man-Whitney and square-qui test. On the base line, alI the variables analyzed were similar on both tested groups. On both groups, for the total of streptococcus there was no significant difference along the time and for S. mutans there was a statistic significant increase of the CFUs from the base line to the zero time. For the total of lactobaccilus there was no significant difference on the test group along the time, and on the control there was a significant increase ofthe CFUs ITom the base line to the zero time. For both groups, there was significant decrease ofthe perceptible bacterial film index along the time, and that can be explained by the mechanic effect of the mouthrinse over the bacterial film and by the participation of the students on the research which could have motivated him to a better toothbrushing (Hawthome effect). The gingival bleeding index also showed a decrease along the time, even though it was not significant. Therefore, the conclusion of this study was that the chitosan at 0.4 % mouthrinse was not effective on the CFUs reduction of the three bacterial groups analyzed, as well as on the reduction of the perceptible bacterial film and gingival bleeding indices

Sistema de produção misto de caprino na região central do estado do Rio Grande do Norte

This study aimed to evaluate the performance and profitability of Canindé goats kept under semi-intensive management in mix farming system. 84 animals were used, being 81 does e three bucks.. The means of fertility rate at parturition, prolificacy and percentages of pregnant, kid survival and reproductive rate were compared by Tukey test at significance level of 5.0%. The kid weights from birth to weaning were submitted to variance analysis considering sex and birth type and the means were compared by Tukey test at 5.0% of significance. The percentages of fertility rate by ultrassographic were 91.36 and parturition 74.84. The prolificacy was 1.53. Independently of sex the mortality rate of kids from birth to weaning was 12.3. The average weights of offspring were 2.11 and 1.92 kg and 6.74 and 6.84 kg for male and female offspring at birth and weaning, in this order. The average weights of kids, meaning PN, P28, P56, P63, in the first season of kidding were 2.11 ± 0.46 kg, 3.63 ± 1.04 kg, 5.96 ± 158 kg and 6.74 ± 1.79 kg. There was significant differences (P<0,05) only to birth weight of kids sons of buck 135. However, the fertility at parturition for first and second breeding seasons (BS) were 87.65 and 62.96, respectively (P<0.05). The prolificacy was 1.58 and 1.47 to first and second BS in this order. The percentages of offspring survival from birth to weaning, to first and second BS were 92.86 and 80.00, respectively. From the first BS the reproduction rate was 1.28 while in the second was 0.74. After weaning the duration of lactation was 104 days to first breeding parturition and 38 days in the second one. The total milk production was 853.50 kg. The kids weight gain was influenced by season of year, wet and dry and buck (P<0.05). Were concluded that the seasons of year when breeding season and parturition occur strongly affected the productive performance and profitability of production system

Degradação térmica e catalítica do resíduo atmosférico de petróleo (RAT), utilizando materiais nanoestruturados do tipo SBA-15

In this work were synthesized and characterized the materials mesoporous SBA-15 and Al- SBA-15, Si / Al = 25, 50 and 75, discovered by researchers at the University of California- Santa Barbara, USA, with pore diameters ranging from 2 to 30 nm and wall thickness from 3.1 to 6.4 nm, making these promising materials in the field of catalysis, particularly for petroleum refining (catalytic cracking), as their mesopores facilitate access of the molecules constituting the oil to active sites, thereby increasing the production of hydrocarbons in the range of light and medium. To verify that the materials used as catalysts were successfully synthesized, they were characterized using techniques of X-ray diffraction (XRD), absorption spectroscopy in the infrared Fourier transform (FT-IR) and adsorption nitrogen (BET). Aiming to check the catalytic activity thereof, a sample of atmospheric residue oil (ATR) from the pole Guamaré-RN was performed the process by means of thermogravimetry and thermal degradation of catalytic residue. Upon the curves, it was observed a reduction in the onset temperature of the decomposition process of catalytic ATR. For the kinetic model proposed by Flynn-Wall yielded some parameters to determine the apparent activation energy of decomposition, being shown the efficiency of mesoporous materials, since there was a decrease in the activation energy for the reactions using catalysts. The ATR was also subjected to pyrolysis process using a pyrolyzer with gas chromatography coupled to a mass spectrometer. Through the chromatograms obtained, there was an increase in the yield of the compounds in the range of gasoline and diesel from the catalytic pyrolysis, with emphasis on Al-SBA-15 (Si / Al = 25), which showed a percentage higher than the other catalysts. These results are due to the fact that the synthesized materials exhibit specific properties for application in the process of pyrolysis of complex molecules and high molecular weight as constituents of the ATR

Interações entre a carboximetilcelulose, carbonato de cálcio e bentonita: repercussões sobre as propriedades dos fluidos de perfuração aquosos

The role of carboxymethylcellulose (CMC) in association to calcium carbonate particles (CaCO3) in most water-based drilling fluids is to reduce the fluid loss to the surrounding formation. Another essential function is to provide rheological properties capable of maintaining in suspension the cuttings during drilling operation. Therefore, it is absolutely essential to correlate the polymer chemical structure (degree of substitution, molecular weight and distribution of substituent) with the physical-chemical properties of CaCO3, in order to obtain the better result at lower cost. Another important aspect refers to the clay hydration inhibitive properties of carboxymethylcellulose (CMC) in drilling fluids systems. The clay swelling promotes an undesirable damage that reduces the formation permeability and causes serious problems during the drilling operation. In this context, this thesis consists of two main parts. The first part refers to understanding of interactions CMC-CaCO3, as well as the corresponding effects on the fluid properties. The second part is related to understanding of mechanisms by which CMC adsorption occurs onto the clay surface, where, certainly, polymer chemical structure, ionic strength, molecular weight and its solvency in the medium are responsible to affect intrinsically the clay layers stabilization. Three samples of carboximetilcellulose with different molecular weight and degree of substitution (CMC A (9 x 104 gmol DS 0.7), CMC B (2.5 x 105 gmol DS 0.7) e CMC C (2.5 x 105 gmol DS 1.2)) and three samples of calcite with different average particle diameter and particle size distribution were used. The increase of CMC degree of substitution contributed to increase of polymer charge density and therefore, reduced its stability in brine, promoting the aggregation with the increase of filtrate volume. On the other hand, the increase of molecular weight promoted an increase of rheological properties with reduction of filtrate volume. Both effects are directly associated to hydrodynamic volume of polymer molecule in the medium. The granulometry of CaCO3 particles influenced not only the rheological properties, due to adsorption of polymers, but also the filtration properties. It was observed that the lower filtrate volume was obtained by using a CaCO3 sample of a low average size particle with wide dispersion in size. With regards to inhibition of clay swelling, the CMC performance was compared to other products often used (sodium chloride (NaCl), potassium chloride (KCl) and quaternary amine-based commercial inhibitor). The low molecular weight CMC (9 x 104 g/mol) showed slightly lower swelling degree compared to the high molecular weight (2.5 x 105 g/mol) along to 180 minutes. In parallel, it can be visualized by Scanning Electron Microscopy (SEM) that the high molecular weight CMC (2.5 x 105 g/mol e DS 0.7) promoted a reduction in pores formation and size of clay compared to low molecular weight CMC (9.0 x 104 g/mol e DS 0.7), after 1000 minutes in aqueous medium. This behavior was attributed to dynamic of interactions between clay and the hydrodynamic volume of CMC along the time, which is result of strong contribution of electrostatic interactions and hydrogen bounds between carboxylate groups and hydroxyls located along the polymer backbone and ionic and polar groups of clay surface. CMC adsorbs on clay surface promoting the skin formation , which is responsible to minimize the migration of water to porous medium. With the increase of degree of substitution, it was observed an increase of pores onto clay, suggesting that the higher charge density on polymer is responsible to decrease its flexibility and adsorption onto clay surface. The joint evaluation of these results indicate that high molecular weight is responsible to better results on control of rheological, filtration and clay swelling properties, however, the contrary effect is observed with the increase of degree of substitution. On its turn, the calcite presents better results of rheological and filtration properties with the decrease of average viii particle diameter and increase of particle size distribution. According to all properties evaluated, it has been obvious the interaction of CMC with the minerals (CaCO3 and clay) in the aqueous medium