In this work, the nonisothermal sintering behavior of as-received commercial high purity ZnO micrometric (m-ZnO), submicrometric (sm-ZnO) and nanometric (n-ZnO) powders was studied. The sintering behavior for sputtering target production was evaluated by changing the green density of samples from 62% of theoretical density (TD) to 35%. We observed that for n-ZnO powder, the maximum shrinkage rate (MSR) temperature (T MSR) was not affected by the green density, and that it was reached at lower temperatures (∼710°C) compared with m-ZnO and sm-ZnO powders. For these powders, the temperature of MSR increased from 803°C to 934°C and from 719°C to 803°C as TD changed from 62% to 35% TD, respectively. Small grain size (∼0.560 μm) and high density targets were obtained for n-ZnO when sintered at temperatures below the T MSR. Heating rate from 1°C to 15°C/min led to lower activation energy for n-ZnO (∼201 ± 3 kJ/mol) than for the submicrometric (sm-ZnO) (∼332 ± 20 kJ/mol) and micrometric (m-ZnO) (∼273 ± 9 kJ/mol) powders. Using the model proposed by Bannister and Woolfrey, an n value of 0.75 was found, which was correlated with a combination of viscous flow and volume diffusion mechanisms that should control the initial stage of n-ZnO sintering. No significant differences were observed for n-ZnO powder in terms of density when the size of targets (scale-up effect) was increased, while in the case of m-ZnO and sm-ZnO, a delay in the densification was observed, which was related to the higher sinterability of n-ZnO powder. Two inches ZnO ceramic targets with different particle sizes and final densities were used in an rf magnetron sputtering system to produce ZnO films under the same deposition conditions. Films with thickness around 100 nm and good uniformity were produced using those targets, and no variation was observed in the optical and morphological properties. However, low electrical resistivity (1.4 Omega;·cm) films were obtained with n-ZnO targets, which could be explained in terms of a nonstoichiometric Zn:O composition of the started powders. © 2011 The American Ceramic Society.

Barium zinc borosilicate glasses with a molar composition xBaO-(60-x)ZnO-30B 2O 3-10SiO 2, where x ranged from 0 to 60 mol%, were prepared using melt-quenching method. The effect of BaO substitution for ZnO on the sintering, crystallization, and dielectric characteristics has been investigated. The behavior of the studied barium zinc borosilicate glasses was mainly determined by the relative amount of the structural modifier oxides (BaO and ZnO) and the ionic size, and field strength of the modifying cations (Ba 2+, Zn 2+). Increased amounts of BaO decreased both glass transition temperature and crystallization temperature, while increasing the relative dielectric constant. Sintering occurred before crystallization for glasses where substitution of BaO for ZnO was up to 30 mol%, but for higher substitution levels, crystallization occurred during the sintering process hindering densification. © 2012 The American Ceramic Society.

Ferritins are ubiquitous and can be found in practically all organisms that utilize Fe. They are composed of 24 subunits forming a hollow sphere with an inner cavity of similar to 80 angstrom in diameter. The main function of ferritin is to oxidize the cytotoxic Fe2+ ions and store the oxidized Fe in the inner cavity. It has been established that the initial step of rapid oxidation of Fe2+ (ferroxidation) by H-type ferritins, found in vertebrates, occurs at a diiron binding center, termed the ferroxidase center. In bacterial ferritins, however, X-ray crystallographic evidence and amino acid sequence analysis revealed a trinuclear Fe binding center comprising a binuclear Fe binding center (sites A and B), homologous to the ferroxidase center of H-type ferritin, and an adjacent mononuclear Fe binding site (site C). In an effort to obtain further evidence supporting the presence of a trinuclear Fe binding center in bacterial ferritins and to gain information on the states of the iron bound to the trinuclear center, bacterial ferritin from Desulfovibrio vulgaris (DvFtn) and its E130A variant was loaded with substoichiometric amounts of Fe2+, and the products were characterized by Mossbauer and EPR spectroscopy. Four distinct Fe species were identified: a paramagnetic diferrous species, a diamagnetic diferrous species, a mixed valence Fe2+Fe3+ species, and a mononuclear Fe2+ species. The latter three species were detected in the wild-type DvFtn, while the paramagnetic diferrous species was detected in the E130A variant. These observations can be rationally explained by the presence of a trinuclear Fe binding center, and the four Fe species can be properly assigned to the three Fe binding sites. Further, our spectroscopic data suggest that (1) the fully occupied trinuclear center supports an all ferrous state, (2) sites B and C are bridged by a mu-OH group forming a diiron subcenter within the trinuclear center, and (3) this subcenter can afford both a mixed valence Fe2+Fe3+ state and a diferrous state. Mechanistic insights provided by these new findings are discussed and a minimal mechanistic scheme involving O-O bond cleavage is proposed.

Borosilicate glass-alumina composites with (1 - x) Glass + x Al 2O 3 (x = 0, 5, 10, 25 vol.%) were prepared and the effect of Al 2O 3 addition on the structural, electrical and thermal characteristics was investigated. XRD patterns revealed the presence of cristobalite (SiO 2) in sintered borosilicate glass and that the addition of Al 2O 3 hinders cristobalite formation. This behavior is due to the diffusion of some Al 3+ ions from alumina to glass, which leads to changes in glass structure and composition as identified by SEM/EDS. Cristobalite was undetected in composites containing 10% Al 2O 3 that attained the lowest thermal expansion coefficient value (∼4.6 × 10 -6 °C -1). Conductivity (dc and ac) increased with the amount of Al 3+ ions present in the glass structure as modifiers and formers. Dielectric constant values, in the range 5.0-7.2, increased with Al 2O 3 addition and the values of loss tan δ (1.5-2.1 × 10 -2) indicate that these materials are good insulators. © 2012 Elsevier B.V. All rights reserved.

This paper reports the application of a polymethacrylate hydroxyethylene resin based electrolyte in electrochromic (EC) devices. The electrolyte is characterized by electrochemical impedance spectroscopy, visible spectroscopy, TGA, DSC, and DRX and tested as an ionic conductor in an EC device with the following configuration: Substrate/IZO/WO 3/Polymer Electrolyte/(CeO 2)TiO 2/IZO/Substrate. The electrolyte presents an ionic conductivity of 10 -7S/cm at room temperature and TGA analysis show that electrolyte is thermally degraded at 200°C. The EC device based on this polymethacrylate hydroxyethylene resin electrolyte system shows memory effect and exhibits an excellent optical density. © 2011 John Wiley & Sons, Ltd.

The accumulation of lead in several bones of Wistar rats with time was determined and compared Q3 for the different types of bones. Two groups were studied: a control group (n = 20), not exposed to lead and a contaminated group (n = 30), exposed to lead from birth, first indirectly throughmother’s milk, and then directly through a diet containing lead acetate in drinking water (0.2%). Rats age ranged from 1 to 11 months, with approximately 1 month intervals and each of the collections had 3 contaminated rats and 2 control rats. Iliac, femur, tibia–fibula and skull have been analysed by energy dispersive X-ray fluorescence technique (EDXRF). Samples of formaldehyde used to preserve the bone tissues were also analysed by Electrothermal Atomic Absorption (ETAAS), showing that there was no significant loss of lead from the tissue to the preservative. The bones mean lead concentration of exposed rats range from 100 to 300 mg g 1 while control rats never exceeded 10 mg g 1. Mean bone lead concentrations were compared andthe concentrations were higher in iliac, femur and tibia–fibula and after that skull. However, of all the concentrations in the different collections, only those in the skull were statistically Q4 significantly different (p o 0.05) from the other types of bones. Analysis of a radar chart also allowed us to say that these differences tend to diminish with age. The Spearman correlation test applied to mean lead concentrations showed strong and very strong positive correlations betweenall different types of bones. This test also showed that mean lead concentrations in bones are negatively correlated with the age of the animals. This correlation is strong in iliac and femur and very strong in tibia–fibula and skull. It was also shown that the decrease of lead accumulation with age is made by three plateaus of accumulation,

Supply chains are facing numerous changes that are contributing to increasing their complexity and vulnerability to disturbances, therefore, to survive, supply chains must be resilient. The paper presents a supply chain simulation study for a real case concerned with the Portuguese automotive supply chain. The subset automotive supply chain involved in the case study is a three-echelon supply chain, composed by one automaker, two 1st-tier suppliers, two 2nd-tier suppliers, and one outsource entity. The purpose of the study is to evaluate alternative supply chain scenarios for improving supply chain resilience to a disturbance and understanding how mitigation strategies affect each supply chain entity performance. Two strategies widely used to mitigate disturbance negative effects on supply chains were considered and six scenarios were designed. The scenarios differ in terms of presence or absence of a disturbance in one hand and presence or absence of a mitigation strategy in other hand. To evaluate the scenarios designed, two performance measures were defined per supply chain entity, Lead Time Ratio and Total Cost.

This paper proposes a model for management of supply chain resilience. To this end the structured content analysis of media news is used to analyze a sample constituted by sixty two documents containing evidences of seventy seven companies that were affected by the Japan 2011 earthquake. The sample provides evidences that companies failed to sustain their operations mainly because capacity shortages and material shortages. Also provides empirical evidence of twelve resilience practices to reduce the disturbance severity and the recovery time. Based on these findings four propositions were made and aggregated to propose a model for supply chain resilience management.

The enzymatic (tyrosinase) and chemical (NaIO4, Ag2O or Fremys's salt) oxidation of biologically relevant catecholamines, such as dopamine (DA), N-acetyldopamine (NADA) and the Ecstasy metabolites (alpha-MeDA and N-Me-alpha-MeDA) generates the corresponding o-quinone which can be trapped with nitrogen bionucleophiles such as N-acetyl-histidine and imidazole in a regioselective reaction that takes place predominantly at the 6-position of the catecholamine. (C) 2012 Elsevier Inc. All rights reserved.

Suppose \(\alpha\) is an orientation preserving diffeomorphism (shift) of \(\mathbb{R}_+=(0,\infty)\) onto itself with the only fixed points \(0\) and \(\infty\). We establish sufficient conditions for the Fredholmness of the singular integral operator with shift \[ (aI-bW_\alpha)P_++(cI-dW_\alpha)P_- \] acting on \(L^p(\mathbb{R}_+)\) with \( 1 < p < \infty \), where \(P_\pm=(I\pm S)/2\), \(S\) is the Cauchy singular integral operator, and \(W_\alpha f=f\circ\alpha\) is the shift operator, under the assumptions that the coefficients \(a,b,c,d\) and the derivative \(\alpha'\) of the shift are bounded and continuous on \(\mathbb{R}_+\) and may admit discontinuities of slowly oscillating type at \(0\) and \(\infty\).

Saturation transfer difference (STD) NMR has emerged as one of the most popular ligand-based NMR techniques for the study of protein−ligand interactions. The success of this technique is a consequence of its robustness and the fact that it is focused on the signals of the ligand, without any need of processing NMR information about the receptor and only using small quantities of nonlabeled macromolecule. Moreover, the attractiveness of this experiment is also extendable to the classroom. In the context of a practical NMR class, this experiment is ideal to illustrate some fundamental NMR concepts, such as the nuclear Overhauser effect and relaxation in a multidisciplinary context, bridging chemistry and biochemistry with a taste of medicinal chemistry.

We use the readily available human serum albumin (HSA), 6-d,l-methyl-tryptophan (6-CH3-Trp), and 7- d,l-methyl-tryptophan (7-CH3-Trp) to introduce the STD-NMR experiment and to illustrate its applicability for ligand screening, mapping of binding moieties, and determination of the dissociation constant, in a context that can be explored or adapted to the student’s course level and topic (chemistry or biochemistry). We also cover the most important theoretical aspects of the STD experiment, calling attention to some of its limitations and drawbacks without a complex theoretical approach.

Scenario modeling can be realized through different perspectives. In UML, scenarios are often modeled with activity models, in an early stage of development. Later, sequence diagrams are used to detail object interactions. The migration from activity diagrams to sequence diagrams is a repetitive and error-prone task. Model-Driven Development (MDD) can help streamlining this process, through transformation rules. Since the information in the activity model is insufficient to generate the corresponding complete sequence model, manual refinements are required. Our goal is to compare the relative effort of building the sequence diagrams manually with that of building them semi-automatically. Our results show a decrease in the number of operations required to build and refine the sequence model of approximately 64% when using MDD, when compared to the manual approach.