Weight Gain Curves Research Articles

Corrosion behavior of a 14Cr-ODS steel in supercritical water

The corrosion behavior of a 14Cr-ODS steel in the supercritical water was investigated using a variety of characterization techniques. Compared with 316L austenitic steel, the 14Cr-ODS steel had better corrosion resistant property. As the increasing of the exposure time, the weight gain increased, but the corrosion rates decreased. The curve of weight gain as a function of time followed a parabolic law. The general weight gain was 0.3476mg/(dm2h). A triple layer was observed which consisted of an outer layer, an inner layer and a diffusion layer. The outer layer was iron rich and contained Fe3O4, on which pores were observed. The inner layer and diffusion layer contained mainly (Fe,Cr2)O4. The oxidation mechanism was also discussed.

Effects of early life permethrin exposure on spatial working memory and on monoamine levels in different brain areas of pre-senescent rats

Pesticide exposure during brain development could represent an important risk factor for the onset of neurodegenerative diseases. Previous studies investigated the effect of permethrin (PERM) administered at 34mg/kg, a dose close to the no observable adverse effect level (NOAEL) from post natal day (PND) 6 to PND 21 in rats. Despite the PERM dose did not elicited overt signs of toxicity (i.e. normal body weight gain curve), it was able to induce striatal neurodegeneration (dopamine and Nurr1 reduction, and lipid peroxidation increase). The present study was designed to characterize the cognitive deficits in the current animal model. When during late adulthood PERM treated rats were tested for spatial working memory performances in a T-maze-rewarded alternation task they took longer to choose for the correct arm in comparison to age matched controls. No differences between groups were found in anxiety-like state, locomotor activity, feeding behavior and spatial orientation task. Our findings showing a selective effect of PERM treatment on the T-maze task point to an involvement of frontal cortico-striatal circuitry rather than to a role for the hippocampus. The predominant disturbances concern the dopamine (DA) depletion in the striatum and, the serotonin (5-HT) and noradrenaline (NE) unbalance together with a hypometabolic state in the medial prefrontal cortex area. In the hippocampus, an increase of NE and a decrease of DA were observed in PERM treated rats as compared to controls. The concentration of the most representative marker for pyrethroid exposure (3-phenoxybenzoic acid) measured in the urine of rodents 12h after the last treatment was 41.50μg/L and it was completely eliminated after 96h.

Experimental study of glass to metal seals for parabolic trough receivers

Abstract The breakage of the glass to metal sealing is the primary ongoing issue for the solar receiver tubes in parabolic trough solar power systems. Sealing failure leads to loss of the vacuum inside the tube which substantially reduces the collector efficiency. It is a technical difficulty to obtain good glass to metal seals with high mechanical strength and long-term temperature resistance during current receiver manufacturing. The paper describes the development of the glass to metal seals in the parabolic trough receivers and presents a new method that uses the high-frequency induction heating to band a new borosilicate glass to the Kovar alloy ends. Kovar pre-oxidization experiments were used to measure the relation curves of Kovar oxidation weight gain during heating. The preoxidation of Kovar and the sealing process are guided by a series tests to measure the gas tightness, sealing strength, seal interface microstructure and thermal shock. The results show that excellent glass-to-Kovar sealing can be obtained with a Kovar oxidation weight gain of about 0.3–0.8 mg/cm2. Finally, a new solar receiver was developed by the new sealing method.

The Oxidation Mechanism of Pure Aluminum Powder Particles

The oxidation mechanism of aluminum powder particles was studied by simultaneous TG–DTA analysis (under air atmosphere) at different heating rates (10, 20 and 30 °C/min) and from an ambient temperature up to 1,400 °C. Also, the rate of oxidation reaction (rate of weight gain; RTG) was obtained by the differentiation of weight gain (TGG) curve. Additionally, SEM and X-ray diffraction analysis (XRD) studies were performed on each of the above samples for their structural and phase studies. The results obtained from TG–DTA and RTG curves; microstructure and phase analysis studies indicated that the oxidation of aluminum powders occurred during five stages. On the other hand, according to the results obtained from XRD and TGG curves, aluminum particles after the thermal analysis test, even heated up to 1,400 °C, were not entirely oxidized (i.e. less than 10 %).

Moisture diffusion and hygrothermal aging in pultruded fibre reinforced polymer composites of bridge decks

Gravimetric experimental studies were undertaken to characterise the moisture diffusion process in pultruded Fibre Reinforced Polymer (FRP) composites of bridge decks exposed to the vapour environmental aging condition as well as water immersed condition at temperatures of 20°C and 40°C respectively. After a short-term (250days) aging duration, the moisture weight gain curves as a function of time were obtained. Comparing with the vapour conditions, FRP composites immersed in water resulted in much higher moisture uptake levels, around 3% of the initial self-weight. Based on the one-dimensional moisture diffusion theory, the moisture diffusion coefficients of FRP composites under different aging conditions were identified by the best least-square curve fitting to the experimental data. The obtained results indicated that high temperature can speed up the moisture diffusion rate, and the moisture equilibrium contents were mainly governed by the humidity of aging environment. Large portion of polymer relaxation was evident from the experimental data in the aging condition of 20°C-water and 40°C-water. Moisture desorption tests confirmed that, for the aging conditions of 40°C-96% relative humidity (RH) and 40°C-water, mass loss of FRP composites took place. No significant variations on moisture diffusion characteristic of FRP specimens from different parts of the bridge deck element can be drawn expect that, flange part specimens absorbed less moisture content than the two web parts.

Evaluation of Sulfidation Resistance of Atomized Fe40Al Based Intermetallics

ABSTRACTThe isothermal oxidation-sulfidation of Fe-40Al based intermetallics alloys in N2/SO2 gas mixture at 625, 700 and 775°C were evaluated. Fe40Al, Fe40Al+0.1B, Fe40Al+0.1B+10Al2O3 alloys were produced by atomization and deposition. Isothermal gas exposition was reached during 48 hours. FeAl based alloys showed good sulfidation resistance, presenting both small weight gain and weight change fluctuations. At 625°C, the Fe40Al+0.1B alloy had the biggest weight gain; on the other hand the Fe40Al alloy exhibited the biggest sulfidation resistance. At 700 and 775°C, the Fe40Al+0.1B alloy presented the smallest weight gain, however Fe40Al alloy presented higher weight gain, that is to say, the smallest sulfidation resistance at those temperatures. The variation in the weight gain curves were discussed in terms of formation and detachment of sulfides, and by local attack on the alloy surface as the temperature increasing. The results are supplemented with characterization by SEM and analysis of X-rays dispersion.

Decomposition and Oxidation of Magnesium Diboride

The decomposition and oxidation behavior of magnesium diboride (MgB2) have been studied using thermogravimetry (TG), XRD and SEM‐EDS. The reactions were carried out by heating MgB2 powder in a stream of argon or air at atmospheric pressure. In the temperature range explored (298–1673 K), four successive steps were observed in the decomposition process of MgB2. The rate‐limiting steps of the decomposition process were found to be associated with the nucleation or formation of boron‐rich phases. The oxidation process of MgB2 comprised five successive phases in the temperature range explored (298–1673 K). There was close relationship between the decomposition and oxidation behavior of MgB2. Experimental results showed that the decomposition reactions occurred during the oxidation process. The acceleration shown in the weight gain curve can be ascribed to the rapid oxidation of Mg vapor released from the decomposition reactions. The microstructure and composition of the oxide scale formed in the oxidation process were investigated using XRD and SEM‐EDS. The oxide layer structure was identified based on the experimental results in this study.

A study of the evolution of rust on Mo–Cu-bearing fire-resistant steel submitted to simulated atmospheric corrosion

The corrosion evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated by corrosion weight gain, XRD, EPMA, XPS, and polarization curves. The results indicate that the corrosion kinetics is closely related to the rust composition and electrochemical properties. As the corrosion proceeds, the relative content of γ-FeOOH and Fe 3O 4 decreases and α-FeOOH increases, and the rust layer becomes compact and adherent to steel substrate. Molybdenum and copper enrich in the inner rust layer, especially at the bottom of the corrosion nest, forming non-soluble molybdate and Cu(I)-bearing compounds responsible for enhanced corrosion resistance of the rust layer.

High-Temperature Oxidation Resistance of Electroless Ni-P-ZrO<sub>2</sub> Composite Coatings

Electroless Ni-P coating containing ZrO2 particles was successfully co-deposited on low carbon steel substrate. The surface and cross-sectional micrographs of the composite coatings were observed with scanning electron microscopy (SEM). And the chemical composition of the coating was analyzed with energy dispersive spectroscopy (EDS). The oxidation resistance was evaluated by weight gains during high temperature oxidation test. The results showed that the embedded ZrO2 particles with irregular shape uniformly distributed in the entire Ni-P matrix, and the coating showed a good adhesion to the substrate. The weight gain curves of Ni-P-ZrO2 composite coatings and Ni-P coating at 923K oxidation experiments were in accordance with . The ZrO2 particles in Ni-P matrix could significantly enhance the high temperature oxidation resistance of the carbon steel substrate as compared to pure Ni-P coating.

Efficacy of a Combined Intracerebral and Systemic Gene Delivery Approach for the Treatment of a Severe Lysosomal Storage Disorder

Multiple sulfatase deficiency (MSD), a severe autosomal recessive disease is caused by mutations in the sulfatase modifying factor 1 gene (Sumf1). We have previously shown that in the Sumf1 knockout mouse model (Sumf1(-/-)) sulfatase activities are completely absent and, similarly to MSD patients, this mouse model displays growth retardation and early mortality. The severity of the phenotype makes MSD unsuitable to be treated by enzyme replacement or bone marrow transplantation, hence the importance of testing the efficacy of novel treatment strategies. Here we show that recombinant adeno-associated virus serotype 9 (rAAV9) vector injected into the cerebral ventricles of neonatal mice resulted in efficient and widespread transduction of the brain parenchyma. In addition, we compared a combined, intracerebral ventricles and systemic, administration of an rAAV9 vector encoding SUMF1 gene to the single administrations-either directly in brain, or systemic alone -in MSD mice. The combined treatment resulted in the global activation of sulfatases, near-complete clearance of glycosaminoglycans (GAGs) and decrease of inflammation in both the central nervous system (CNS) and visceral organs. Furthermore, behavioral abilities were improved by the combined treatment. These results underscore that the "combined" mode of rAAV9 vector administration is an efficient option for the treatment of severe whole-body disorders.

The Growth Curves of Northwest American Indian Children Indicate Early Rapid Weight Gain, a Risk Factor for Later Obesity

The childhood obesity epidemic is pronounced among minority groups, including American Indians (AI). AI are underrepresented in the literature and the statistics reported are usually simple prevalence data. This study modeled weight growth curves in a variety of Northwest AI tribes among children aged 0–36 months. State WIC program data collected from 2003–2007 were used to construct sex-specific growth curves with interpretable parameters. In this model, weight=C+S*m+A*(1−exp(−R*m)), where m is age in months, C is birth weight, S is an indicator of post 2-years linear weight growth (“linear” refers to the shape of the curve), A is an indicator of early growth spurt, and R is the rate at which maximum excessive growth is reached. Results show consistent early rapid weight gain. Birth weights in the AI children tended to be close to the CDC 50th percentiles, however median weights reached well above the 50th percentile, and in many cases approached the 90th percentile by 6–9 months of age, and remained elevated through 3 years of age. Given this early pattern of rapid growth and its implications for later obesity, interventions aimed at preventing childhood obesity in AI populations should not neglect the perinatal and infancy periods. Research Support: National Heart, Lung, and Blood Institute grant U01HL081624; National Institute of Child Health and Development grant R01HD058061-Administrative Supplement

Effects of Fe and Cr on corrosion behavior of ZrFeCr alloys in 500 °C steam

A study of the corrosion behaviors of ZrFeCr alloy and the influence of microstructure on corrosion resistance are described by X-ray diffraction and scanning electron microscope in this paper. The results show that several ZrFeCr alloys exhibit protective behavior throughout the test and oxide growth is stable and protective. The best alloy has the composition Zr1.0Fe0.6Cr. Fitting of the weight gain curves for the protective oxide alloys in the region of protective behavior, it showed nearly cubic behavior for the most protective alloys. The Zr1.0Fe0.6Cr has the more laves Zr(Fe,Cr) 2 precipitate in matrix and it has the better corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, the biggest hydrogen absorption and the worst corrosion resistance. The number of precipitates and the amount of hydrogen absorption in Zr alloy plays an important role on corrosion resistance behaviors in 500 °C/10.3 MPa steam.

Kinetic Study and Reaction Mechanism of Vinyl Monomer Modified Antheraea assama Silk Composites

A biodegradable protein fiber Antheraea assama silk (SH) was modified by using graft co-polymerization technique with methyl methacrylate (MMA: vinyl monomer) and cerric ammonium sulfate (Ce IV ). The grafting process was dependent on MMA, Ce. time factors, temperatures and other properties of the fibroin composites. The possible mechanism of the SHMMA composite was explained by free radical co-polymerization, and the thermal properties were characterized by thermogravimetric analysis (TGA). differential thermogravimetry (DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The kinetic parameters were also studied using the Coats and Redfem method with FORTRAN 77 computer programming and evaluating the activation energy. The structural changes of SHMMA, changes of the crystalline and amorphous characteristics after chemical process with MMA-Ce IV initiator, were discussed in relation to the weight gain and X-ray diffraction curves. This study shows that silk fibroin composites modified by graft co-polymerization have improved thermal stability and chemical stability, which improve the drawbacks and make the silk fibroin a promising material in constructing textiles.

Risky vs Rapid Growth in Infancy

To systematically analyze growth data from infant health maintenance records to characterize infant weight gain increasing risk for childhood overweight, and to identify additional information from those records that could refine risky infant weight gain as a screening tool. Retrospective cohort study. A pediatric office in central Pennsylvania. Children aged 6 to 8 years (n = 129) born in 2000 or later who attended health maintenance visits. Risky infant weight gain was a cutoff selected after considering its sensitivity and specificity during the interval best predicting childhood overweight risk as determined with receiver operating characteristic curve analysis. We identified demographic, growth pattern, and parental feeding choice differences between at-risk infants who did and did not become overweight children. Childhood overweight, defined as a sex- and age-specific body mass index of the 85th percentile or higher at ages 6 to 8 years according to 2000 Centers for Disease Control and Prevention growth charts. Childhood overweight prevalence was 24.8%. At-risk infants gained at least 8.15 kg from ages 0 to 24 months. While 31.4% of at-risk infants became overweight children, 68.6% were resilient. At-risk, resilient participants had parents with more education, had lower weight gain from ages 18 to 24 months and 0 to 24 months and a smaller area under the weight-gain curve from ages 0 to 24 months, were more often exclusively breastfed for 6 months or longer, and were introduced to solid foods later than at-risk, overweight participants. While most researchers would not recognize weight gain of 8.15 kg or more from ages 0 to 24 months as rapid growth, it was a fair screening tool for childhood overweight in our sample and had the potential to be refined using information about demographic characteristics, growth patterns, and parental feeding choices.

Crystal structure change of Li 2+xTiO 3+y tritium breeder under moist air

To investigate the aging behavior of Li 2+ x TiO 3+ y , the materials Li 2.0TiO 3+ y , Li 2.2TiO 3+ y and Li 2.4TiO 3+ y were stored under moist air at ambient temperature. Under these conditions the weight of Li 2.0TiO 3+ y increased by only 1% in 100 days, which provides evidence for the high chemical stability of Li 2TiO 3. In comparison, under the same storage conditions the weights of Li 2.2TiO 3+ y and Li 2.4TiO 3+ y increased by 14% and 18%, respectively. The observed weight gain is attributed to the uptake of water, and to the reaction of a by-product of Li 2+ x TiO 3+ y with water and carbon dioxide. The weight gain curves were evaluated by the Jander equation. From the analysis, it was possible to obtain the diffusion coefficient of water through Li 2TiO 3 particles at ambient temperature. The determined value was 2 × 10 −17 m 2/s.

Usage comparé des courbes de l’Organisation mondiale de la santé et des courbes françaises dans le suivi de la croissance pondérale des jeunes nourrissons

The WHO curves published in 2006 reflect the exact growth of infants who are exclusively breast-fed for at least 4 months. These curves are universal but not widely used in France. At 2-3 months, they have a much higher level than the curves of the Personal Child Health Record. The aim of our study was to evaluate whether the choice of the type of curve influenced the interpretation of infant growth and the advice given, and whether WHO curves could be used for all infants. Initially, 22 physicians retrospectively interpreted the WHO and Personal Child Health Record weight gain curves of 20 infants who were exclusively breast-fed. All of the curves were interpreted twice. In a second step, we drew the WHO curves from 0 to 3 months for the 151 infants monitored by the consultation. At 2 months, there is a very clear discordance in the interpretations of the French and WHO curves (weighted kappa = -0.26 CI 95% [-0.62; 0.18]), contrasting with the satisfactory concordance of the WHO interpretations (weighted kappa = 0.71 CI 95% [0.25; 0.89]) and Personal Child Health Record (weighted kappa = 0.58 CI 95% [0.09; 0.81]) curves. By overestimating the weight gain during the first weeks, in one-third of the infants use of the French curves leads to either inappropriate suggestions of restrictions or their insufficient weight not being taken into account. Moreover, the weight gain at 2-3 months for 151 infants of all categories is within the limits of the WHO curves, without going below the percentile lines for the non-breast-fed infants, except premature babies. Broader use of the WHO curves could be proposed in order to optimize the care of infants, regardless of how they are fed.

Some Physical Properties and Structure Determination of Vinyl Monomer-Grafted Antheraea assama Silk Fiber

Vinyl monomer was used in aqueous medium with CeIV initiator for chemical modification of Antheraea assama silk fiber at different reaction conditions. The rate of grafting (%) was evaluated as a function of the concentration of monomer (AAm) and initiator (CeIV). The graft copolymerization of silk-fibroin with vinyl monomer (acryl amide) were characterized with Fourier transform infrared spectroscopy (FT-IR) and UV−vis spectroscopy (UV). Thermal analysis was done by thermogravimetric (TG), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC) techniques. The kinetic parameters were also studied using Coats and Redfern method with Fortran 77 computer programming. The structural changes of the silk molecule, grafted with vinyl monomer, were studied in relation to the weight gain and X-ray diffraction curves. Moreover, the grafted products were further evaluated to see the improvement in water staining, water retention capacity, and also tensile properties.

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn 3, NdIn 3, and LaPb 3 is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21–28 °C/20–56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn 3 is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb 3 is the secondary and NdIn 3 is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH) 3 after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

On the origin of the sigmoid shape in the UO 2 oxidation weight gain curves

Cracking and spalling are known to occur during the oxidation of UO 2. However, these phenomena are not considered by the existing kinetic models of the oxidation of UO 2 into U 3O 8. In this study the oxidation of UO 2 samples of various sizes from the single crystal to nanopowders, has been followed by isothermal and isobaric thermogravimetry, environmental scanning electron microscopy and in situ X-ray diffraction at temperatures ranging from 250 to 370 °C in air. It has been shown that cracking occurs once a critical layer thickness of intermediate oxide has been reached, which corresponds to the beginning of the sigmoid kinetic curve. Cracking contribution to the sigmoid kinetic curve is then discussed as a function of temperature, and on the basis of nucleation and growth processes.

Kinetics and 13C NMR Study of Oxygen Incorporation into PVC- and Pitch-Derived Materials

The kinetics of oxygen incorporation into a PVC-derived material with pitch-like characteristics was studied by isothermal thermogravimetric analysis at temperatures ranging from 200 to 270 °C. Activation energy, Ea, pre-exponential factor, A, and rate constants, kT, were obtained from the weight-gain curves recorded during reactions of the material with molecular oxygen, which were analyzed following a kinetic first-order model. The numerical values obtained were Ea = 100.5 kJ/mol and A = 1.6 × 1010 h−1. The extent of the oxidation at a fixed temperature was monitored by elemental analysis, and the chemical changes in the materials were followed by solid-state 13C NMR. The study was next extended to the chars obtained from three coal tar pitches with different softening points (55, 85, and 110 °C). Comparisons were then established between the determined kinetic parameters and the chemical/structural aspects and compositions of each analyzed material.