On‐line multivariate optimization of injection molding

An auxiliary process controller was designed, implemented, and validated for on‐line process and quality optimization. The objective function included terms related to the process variation, model uncertainty, and control energy. The controller architecture relied on characterized models including both process transfer functions and principal components analysis to perform on‐line optimization in parallel with the physical molding process. New process and quality observations were input to the controller to update the models and provided new settings for the machine controller. Experimentation included characterization with a D‐optimal design of experiments followed by a validation to measure the controller's performance with respect to controller stability, extrinsic material variation, cycle time reduction, and other common manufacturing goals. In every case, the controller was able to reduce the value of the objective function while also improving the part dimensions relative to tight tolerance specifications. While characterization experiments could be costly, the use of the resulting process models greatly speeds convergence and facilitates the consideration of various cost and quality terms in the objective function. POLYM. ENG. SCI., 55:2743–2750, 2015. © 2015 Society of Plastics Engineers     

Adsorption and surface complexation study of L-DOPA on Rutile (α-TiO₂) in NaCl solutions

Dihydroxyphenylalanine (DOPA) and similar molecules are of considerable interest in studies of bioadhesion to minerals, solar cells involving titanium dioxide, and biomedical imaging. However, the extent and mechanisms of DOPA adsorption on oxides in salt solutions are unknown. We report measurements of DOPA adsorption on well-characterized rutile (α-TiO?) particles over a range of pH, ionic strength, and surface coverage as well as a surface complexation model analysis establishing the stoichiometry, model surface speciation, and thermodynamic equilibrium constants, which permits predictions in more complex systems. DOPA forms two surface species on rutile, the proportions of which vary strongly with pH but weakly with ionic strength and surface loading. At pH < 4.5 a species involving four attachment points ("lying down") is important, whereas at pH > 4.5 a species involving only two attachment points via the phenolic oxygens ("standing up") predominates. Based on evidence of strong attachment of DOPA to titanium dioxide from single molecule AFM (Lee, H. et al., Proc. Natl. Acad. Sci.2006, 103, 12999-12003) and studies of catechol adsorption, one or more of the DOPA attachments for each species is inner-sphere, the others are likely to be H-bonds.     

Picture cues and exhaustive search facilitate very young children's memory for location.

Conducted 3 experiments to examine the effects of picture cues and exhaustive search on very young children's memory for the location of hidden objects. In Exp I, 64 2-yr-olds' performance was examined with control and exhaustive search procedures in spatial-only and spatial- and picture-cue conditions. In Exp II, 32 2-yr-olds' performance with the same 2 search procedures was examined in a cue condition that eliminated spatial information. In Exp III, 64 2- and 3-yr-olds' performance with the control and exhaustive search procedures was examined in 2 array conditions that also eliminated spatial information. All experiments confirmed that even 2-yr-olds use picture cues to encode and search for the location of hidden objects. It was also found that while 2-yr-olds' delayed response performance was improved by exhaustive search procedures, this was not true for 3-yr-olds. Apparently, more complete search strategies contribute to the developmental change in young children's localization performance. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of organic carbon supply rates on uranium mobility in a previously bioreduced contaminated sediment

Bioreduction-based strategies for remediating uranium (U)-contaminated sediments face the challenge of maintaining the reduced status of U for long times. Because groundwater influxes continuously bring in oxidizing terminal electron acceptors (O2, NO3(-)), it is necessary to continue supplying organic carbon (OC) to maintain the reducing environment after U bioreduction is achieved. We tested the influence of OC supply rates on mobility of previously microbial reduced uranium U(IV) in contaminated sediments. We found that high degrees of U mobilization occurred when OC supply rates were high, and when the sediment still contained abundant Fe(III). Although 900 days with low levels of OC supply minimized U mobilization, the sediment redox potential increased with time as did extractable U(VI) fractions. Molecular analyses of total microbial activity demonstrated a positive correlation with OC supply and analyses of Geobacteraceae activity (RT-qPCR of 16S rRNA) indicated continued activity even when the effluent Fe(II) became undetectable. These data support our hypothesis on the mechanisms responsible for remobilization of U under reducing conditions; that microbial respiration caused increased (bi)carbonate concentration and formation of stable uranyl carbonate complexes, thereby shifted U(IV)/U(VI) equilibrium to more reducing potentials. The data also suggested that low OC concentrations could not sustain the reducing condition of the sediment for much longer time. Bioreduced U(IV) is not sustainable in an oxidizing environment for a very long time.     

3-Chlorotyrosine, a specific marker of myeloperoxidase-catalyzed oxidation, is markedly elevated in low density lipoprotein isolated from human atherosclerotic intima

Oxidation of LDL may be of pivotal importance in atherogenesis, but the mechanisms that promote oxidation in vivo remain poorly understood. We have explored the possibility that one pathway involves myeloperoxidase, a heme protein secreted by phagocytes. Myeloperoxidase is the only human enzyme known to generate hypochlorous acid (HOCl), a potent oxidizing agent, at physiological halide concentrations. LDL exposed to the complete myeloperoxidase-H2O2-Cl- system underwent chlorination of its protein tyrosyl residues. Treatment of LDL with reagent HOCl resulted in 3-chlorotyrosine formation, implicating HOCl as an intermediate in the enzymatic reaction pathway. In contrast, 3-chlorotyrosine was undetectable in LDL oxidized by hydroxyl radical, copper, iron, hemin, glucose, peroxynitrite, horseradish peroxidase, lactoperoxidase, or lipoxygenase. These results indicate that 3-chlorotyrosine is a specific marker for LDL oxidation by myeloperoxidase. To address the role of myeloperoxidase in promoting LDL oxidation in vivo, we used stable isotope dilution gas chromatography-mass spectrometry to quantify 3-chlorotyrosine in human aortic tissue and in LDL isolated from atherosclerotic lesions. The level of 3-chlorotyrosine in atherosclerotic tissue obtained during vascular surgery was sixfold higher than that of normal aortic intima. Moreover, the level of 3-chlorotyrosine was 30-fold higher in LDL isolated from atherosclerotic intima compared with circulating LDL. The detection of 3-chlorotyrosine in human atherosclerotic lesions indicates that halogenation reactions catalyzed by the myeloperoxidase system of phagocytes constitute one pathway for protein oxidation in vivo. These findings raise the possibility that the myeloperoxidase-H2O2-Cl- system plays a critical role in converting LDL into an atherogenic form.     

Bridging humanitarian operations management and organisational theory

The aim of the editorial note is to introduce the scope of this special issue (SI). We explain our editorial approach and provide a brief summary of eight articles included in the SI following multiple rounds of reviews. Finally, we outline future research questions which stemmed out of the discussions of this SI.     

Social status and patterns of communication in acquainted and unacquainted preschool children.

Communication patterns were investigated related to the emergence and maintenance of social status in young children. 66 preschool children were classified as liked, disliked, or low-impact, using classmates' sociometric nominations. Children were observed interacting in 1 of 2 conditions: as entry child and host to children they did not know, or as entry child and host to children they knew. Results indicated that when entering the play of children they did not know, disliked children were less responsive to peers and more likely to make irrelevant comments than were liked children. With acquainted peers, disliked children were not only less responsive and more irrelevant than liked children, they were also less likely to clearly direct their communication to specific peers. Thus, responsiveness and contributing to coherent conversation appear to be important to both the establishment and maintenance of social status, whereas failure to socially direct communications may occur only after children develop a negative reputation with peers and, thus, may be a factor only in the maintenance of social status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human neutrophils employ the myeloperoxidase-hydrogen peroxide-chloride system to oxidize alpha-amino acids to a family of reactive aldehydes. Mechanistic studies identifying labile intermediates along the reaction pathway

We have recently demonstrated that neutrophils oxidize nearly all of the amino acids commonly found in plasma to a corresponding family of aldehydes in high yield. The reaction is mediated by hypochlorous acid (HOCl), the major oxidant generated by the myeloperoxidase-H2O2-Cl- system of phagocytes. We now present evidence for the underlying mechanism of this reaction, including the structural requirements and reaction intermediates formed. Utilizing mass spectrometry and isotopically labeled amino acids, we rule out hydrogen atom abstraction from the alpha-carbon as the initial event in aldehyde formation during amino acid oxidation, a pathway known to occur with ionizing radiation. Aldehyde generation from amino acids required the presence of an alpha-amino moiety; beta- and epsilon-amino acids did not form aldehydes upon oxidation by either the myeloperoxidase system or HOCl, generating stable monochloramines instead. UV difference spectroscopy, high pressure liquid chromatography, and multinuclear (1H,15N) NMR spectroscopy established that the conversion of alpha-amino acids into aldehydes begins with generation of an unstable alpha-monochloramine, which subsequently decomposes to yield an aldehyde. Precursor product relationships between alpha-amino acid and alpha-monochloramine, and alpha-monochloramine and aldehyde were confirmed by high pressure liquid chromatography purification of the reaction intermediate and subsequent 1H and 15N NMR spectroscopy. Collectively, these results detail the chemical mechanism and reaction intermediates generated during conversion of amino acids into aldehydes by myeloperoxidase-generated HOCl.     

Adult attachment and history of psychotherapy in a normative sample.

The willingness to trust and self-disclose to others, key aspects in the decision to seek psychotherapy, is expected to vary across attachment classifications. The current study examined the association between internal working models of attachment and history of psychotherapy in a middle-class sample of 120 women, who were administered the Adult Attachment Interview (C. George, N. Kaplan, & M. Main, 1985/1996) and the Mental Health Survey (S. A. Riggs & D. Jacobvitz, 2002). Findings supported predictions that security of attachment is linked to history of psychotherapy. Specifically, adults classified as Dismissing were less likely than other adults to report a history of psychotherapy, whereas Secure adults reported the highest rates of couples therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)