Specificity of anodic processes in cyclic voltammetry to the type of carbon used in electrolysis of cryolite-alumina melts

Anodic processes associated with oxidation of carbon anodes used in electrolysis of cryolite-alumina melts, simulating the Hall-Héroult process, were studied by means of cyclic voltammetry in a comparative way at four graphitic carbon materials and at glassy carbon. Conditions were sought that give a current response function characteristic of diffusion-controlled oxidation of the anode by O^2– or oxyfluoride complex anions. Only at glassy carbon anodes are such conditions realized with a linear relation between response current in cyclic voltammetry and Al₂O₃ content in the melt. At the graphitic materials, complex mixed activation and diffusion controlled processes arise that are also relatively irreproducible from one experiment to the next, probably due to irreversible changes of the graphite surfaces. The effects of aluminium metal dissolved in the melt, to simulate practical smelter cell conditions, were also evaluated.     

Characterizing the deformation of cold-rolled copper sheet

An advanced x-ray diffraction technique allows the development of texture components to be monitored and provides supplementary information about the cold work and residual stresses in cold-rolled copper sheet. The new technique confirms the results of an ultrasonic test, except for the ultrasonic test’s sensitivity to grain size. The new x-ray diffraction technique could be adapted to provide in-process, nondestructive evaluation of thin copper sheet, even for material moving at high speeds.     

The Rise of Twitter in the Political Campaign: Searching for Intermedia Agenda‐Setting Effects in the Presidential Primary

Questions exist over the extent to which social media content may bypass, follow, or attract the attention of traditional media. This study sheds light on such dynamics by examining intermedia agenda‐setting effects among the Twitter feeds of the 2012 presidential primary candidates, Twitter feeds of the Republican and Democratic parties, and articles published in the nation's top newspapers. Daily issue frequencies within media were analyzed using time series analysis. A symbiotic relationship was found between agendas in Twitter posts and traditional news, with varying levels of intensity and differential time lags by issue. While traditional media follow candidates on certain topics, on others they are able to predict the political agenda on Twitter.     

Risk Concentration

Nature takes a variety of approaches regarding risk concentration. Stationary life tends to bend but not break, whereas mobile life tends toward risk concentration with stout border protection. Client and network devices tend to follow the latter model.     

Hard Data Is Good to Find

Indices are a common and useful way to summarize a changing field for both the lay and the specialist reader, and it's time that we had them for information security.     

Main and interactive effects of shiftwork, age and work stress on health in an Italian sample of healthcare workers

Among healthcare workers, shiftwork (mostly if nightwork is also included), ageing and work-related stress may be factors leading to impaired health. Such risk factors may also operate in interaction, resulting in an even increased harm for health. The present study aims at evaluating these relationships in a sample of 1842 hospital workers in Northern Italy. Subjects were mainly women, 33.1% were aged > or = 45 yr, and they were almost evenly distributed between dayworkers and rotating shiftworkers (nights included). Shiftwork was associated with poor sleep, while it was protective against gastrointestinal disorders, poor work ability and job dissatisfaction. Work stress was the risk factor with the highest relevance for poor health. Ageing was associated with lower physical health. Few significant interactions were observed. Shiftwork with nights and high work stress significantly interacted in increasing the risk for poor sleep. The "healthy worker effect" may have played a strong role in study findings.     

Chemotherapy with the "8 in 1" protocol for malignant brain tumors in children: a population-based study in Finland

We evaluated the outcome of 68 children with malignant brain tumors treated with the "8 in 1" chemotherapy protocol in Finland from 1986 to 1993, comparing 5-year survival rates with those for a historical control group (from 1975 to 1985). For all malignant brain tumors, overall survival was 43% (vs 28% in the control group; P <0.05), and progression-free survival (PFS) was 43% (vs 23%; P <0.05). For medulloblastoma and primitive neuroectodermal tumor, survival was 63% (vs 35%; P <0.05), and the corresponding PFS was 59% (vs 35%; P = 0.15). For high-grade glioma, both the survival rate and the PFS were 27% (vs 17%; P = NS). Thus the outcome was significantly better for our "8 in 1" -treated patients than for the historical controls, especially among the children with primitive neuroectodermal tumor and medulloblastoma. In contrast, those with high-grade gliomas and brain stem tumors seem to have received little benefit; different, more effective treatments are needed for these patients.     

Evolution of carbohydrate metabolic pathways

Current studies of hyperthermophilic archaea and bacteria, the phylogenetically deepest-rooted and slowest-evolving extant organisms known, are allowing new insights into the nature of presumably ancient metabolic pathways. The apparent common occurrence of modified non-phosphorylated Entner-Doudoroff (ED) pathways among saccharolytic archaea and the absence of the conventional Embden-Meyerhof-Parnas (EMP) mode of glycolysis indicate that the ED pathway is the older route of carbohydrate dissimilation. However, gluconeogenesis via the "reversed" EMP route has been found in archaea. Thus, the EMP pathway was probably an anabolic pathway to begin with; its catabolic role came later, with the evolution of fructose phosphate kinases, using ATP, ADP or pyrophosphate as phosphate donors. Similarly, the presence of reductive reactions of the citric acid cycle in anaerobic archaea and the most deeply rooted bacteria, including autotrophs, indicates that the citric acid cycle was originally a reductive biosynthetic pathway.     

Inhibition of G protein-coupled receptor kinase subtypes by Ca2+/calmodulin

G protein-coupled receptor kinases (GRKs) are implicated in the homologous desensitization of G protein-coupled receptors. Six GRK subtypes have so far been identified, named GRK1 to GRK6. The functional state of the GRKs can be actively regulated in different ways. In particular, it was found that retinal rhodopsin kinase (GRK1), but not the ubiquitous betaARK1 (GRK2), can be inhibited by the photoreceptor-specific Ca2+-binding protein recoverin through direct binding. The present study was aimed to investigate regulation of other GRKs by alternative Ca2+-binding proteins such as calmodulin (CaM). We found that Gbetagamma-activated GRK2 and GRK3 were inhibited by CaM to similar extents (IC50 approximately 2 microM), while a 50-fold more potent inhibitory effect was observed on GRK5 (IC50 = 40 nM). Inhibition by CaM was strictly dependent on Ca2+ and was prevented by the CaM inhibitor CaMBd. Since Gbetagamma, which is a binding target of Ca2+/CaM, is critical for the activation of GRK2 and GRK3, it provides a possible site of interaction between these proteins. However, since GRK5 is Gbetagamma-independent, an alternative mechanism is conceivable. A direct interaction between GRK5 and Ca2+/CaM was revealed using CaM-conjugated Sepharose 4B. This binding does not influence the catalytic activity as demonstrated using the soluble GRK substrate casein. Instead, Ca2+/CaM significantly reduced GRK5 binding to the membrane. The mechanism of GRK5 inhibition appeared to be through direct binding to Ca2+/CaM, resulting in inhibition of membrane association and hence receptor phosphorylation. The present study provides the first evidence for a regulatory effect of Ca2+/CaM on some GRK subtypes, thus expanding the range of different mechanisms regulating the functional states of these kinases.     

Modeling of interfacial intermetallic compounds in the application of very fine lead-free solder interconnections

Intermetallic compounds (IMCs) are formed between lead-free solders and base metals during soldering processes. The morphology as well as the amount of the IMCs, in particular the interfacial IMCs, are important to mechanical performance of the solder joints in their service environment. This is especially the case in state-of-art ultrafine-pitch wafer-level packaging, in which solder joints could become as small as 50 μm in diameter or even less. However, research addressing growth kinetics of the IMCs in the existing literature has concentrated on fitting experimental data onto a simple parabolic growth equation, which cannot account for all the complicated physics involved in the process of IMC formation. There are a few models based on Fick’s diffusion equations in the literature, which assume the growing IMC interface is planar. A combined thermodynamic–kinetic model has been derived from the relationships amongst some thermodynamic parameters; however, this model is only one dimension (1-D) in nature. 2-D models have also been proposed, e.g. an implicit boundary tracking method, and a phase field model. This paper reviews the modeling techniques in the literature for both the growth kinetics and morphology of the interfacial IMCs, under the context of lead-free soldering in very fine interconnections. The advantages and disadvantages of each method are discussed. Possible solutions to include the geometrical features of micro solder joints in the modeling of growth kinetics of interfacial IMC are presented.