Surface Characteristics,Copper Release,and Toxicity of Nano‐ and Micrometer‐Sized Copper and Copper(II) Oxide Particles: A Cross‐Disciplinary Study

An interdisciplinary and multianalytical research effort is undertaken to assess the toxic aspects of thoroughly characterized nano‐ and micrometer‐sized particles of oxidized metallic copper and copper(II) oxide in contact with cultivated lung cells, as well as copper release in relevant media. All particles, except micrometer‐sized Cu, release more copper in serum‐containing cell medium (supplemented Dulbecco's minimal essential medium) compared to identical exposures in phosphate‐buffered saline. Sonication of particles for dispersion prior to exposure has a large effect on the initial copper release from Cu nanoparticles. A clear size‐dependent effect is observed from both a copper release and a toxicity perspective. In agreement with greater released amounts of copper per quantity of particles from the nanometer‐sized particles compared to the micrometer‐sized particles, the nanometer particles cause a higher degree of DNA damage (single‐strand breaks) and cause a significantly higher percentage of cell death compared to cytotoxicity induced by micrometer‐sized particles. Cytotoxic effects related to the released copper fraction are found to be significantly lower than the effects related to particles. No DNA damage is induced by the released copper fraction.     

Emotions, defenses, coping mechanisms, and symptoms.

Used L. A. Gottschalk and G. C. Gleser's (1969) method of content analysis to examine 5-min samples of speech elicited from 6 different groups of Ss: 30 young normal men (mean age 25.7 yrs), 30 normative adults (aged 20–50 yrs), 30 normative schoolchildren (aged 6–26 yrs), 20 adults with psychoneuroses, 44 emotionally disturbed criminal offenders (mean age 25.6 yrs), and 22 acute schizophrenics (aged 21–55 yrs). Ss were given purposely ambiguous standardized instructions simulating the request to free-associate. Findings indicate that displacements and denials in mentally healthy individuals are more likely to function as coping mechanisms in contrast to their function as defenses or symptoms in mentally disordered people. No significant effects of sex, age, intelligence, or state of consciousness were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Static consistency checking of web applications with WebDSL

Modern web application development frameworks provide web application developers with high-level abstractions to improve their productivity. However, their support for static verification of applications is limited. Inconsistencies in an application are often not detected statically, but appear as errors at run-time. The reports about these errors are often obscure and hard to trace back to the source of the inconsistency. A major part of this inadequate consistency checking can be traced back to the lack of linguistic integration of these frameworks. Parts of an application are defined with separate domain-specific languages, which are not checked for consistency with the rest of the application. Examples include regular expressions, query languages and XML-based languages for definition of user interfaces. We give an overview and analysis of typical problems arising in development with frameworks for web application development, with Ruby on Rails, Lift and Seam as representatives.To remedy these problems, in this paper, we argue that domain-specific languages should be designed from the ground up with static verification and cross-aspect consistency checking in mind, providing linguistic integration of domain-specific sub-languages. We show how this approach is applied in the design of WebDSL, a domain-specific language for web applications, by examining how its compiler detects inconsistencies not caught by web frameworks, providing accurate and clear error messages. Furthermore, we show how this consistency analysis can be expressed with a declarative rule-based approach using the Stratego transformation language.     

Imaging of membrane lipids in single cells by imprint-imaging time-of-flight secondary ion mass spectrometry

A new method for identification and localization of organic molecules in biological samples is described. The method involves making an imprint of a biological sample on a silver (Ag) surface and subsequent analysis of the imprint by imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS). Using this method, detection of unfragmented, Ag cationized molecules at a spatial resolution of <0.5 microm is possible. We have used the method to study the spatial distribution of phosphatidylcholine and cholesterol in blood cells adhering to a glass surface. The TOF-SIMS images show that cholesterol is preferentially located in the plasma membrane, whereas the phosphocholine shows highest concentration in the nuclear membrane. Scanning electron microscopy and fluorescence microscopy images show that the amount of transferred material during the imprinting process can be controlled by varying the imprinting pressure and pretreatment of the cell substrate prior to imprinting.     

Modeling analyte transport and capture in porous bead sensors

Porous agarose microbeads, with high surface to volume ratios and high binding densities, are attracting attention as highly sensitive, affordable sensor elements for a variety of high performance bioassays. While such polymer microspheres have been extensively studied and reported on previously and are now moving into real-world clinical practice, very little work has been completed to date to model the convection, diffusion, and binding kinetics of soluble reagents captured within such fibrous networks. Here, we report the development of a three-dimensional computational model and provide the initial evidence for its agreement with experimental outcomes derived from the capture and detection of representative protein and genetic biomolecules in 290 μm porous beads. We compare this model to antibody-mediated capture of C-reactive protein and bovine serum albumin, along with hybridization of oligonucleotide sequences to DNA probes. These results suggest that, due to the porous interior of the agarose bead, internal analyte transport is both diffusion and convection based, and regardless of the nature of analyte, the bead interiors reveal an interesting trickle of convection-driven internal flow. On the basis of this model, the internal to external flow rate ratio is found to be in the range of 1:170 to 1:3100 for beads with agarose concentration ranging from 0.5% to 8% for the sensor ensembles here studied. Further, both model and experimental evidence suggest that binding kinetics strongly affect analyte distribution of captured reagents within the beads. These findings reveal that high association constants create a steep moving boundary in which unbound analytes are held back at the periphery of the bead sensor. Low association constants create a more shallow moving boundary in which unbound analytes diffuse further into the bead before binding. These models agree with experimental evidence and thus serve as a new tool set for the study of bioagent transport processes within a new class of medical microdevices.     

The effects of hemodialysis treatment on the level of DNA strand breaks and oxidative DNA lesions measured by the comet assay

Hemodialysis patients have a higher risk for oxidative stress‐related complications, such as cardiovascular disease and cancer. The increased level of oxidative stress is due to several factors, e.g., the hemodialysis treatment itself and the uremic state. In the present study, the effects of dialysis treatment on the level of DNA breaks and oxidative DNA lesions in mononuclear cells were measured with the comet assay. Factors possibly affecting DNA damage (reported as % DNA in tail) such as the duration of dialysis, time since last dialysis session, years of dialysis treatment, nutritional status (measured as protein catabolic rate), age, and diabetes were also investigated. The levels of DNA breaks (13.6 ± 4.7 before dialysis) and oxidative DNA lesions (7.9 ± 4.8 before dialysis) were significantly higher in dialysis patients (n = 31) compared to the levels of DNA breaks (5.8 ± 1.1) and oxidative DNA lesions (3.4 ± 1.7) in 10 healthy controls (P < 0.001). A decrease of DNA breaks was observed after dialysis (P = 0.038), and the level of oxidative DNA lesions was higher when the time between two treatment sessions were 68 hours compared to 44 hours (P < 0.001). Older subjects had a higher level of DNA breaks (P = 0.003), a good nutritional status predicted a lower level of DNA breaks (P < 0.001), and the duration of the dialysis session was inversely correlated with oxidative DNA lesions (P = 0.014). Diabetes or years of dialysis treatment did not affect DNA damage. The observations in the present study suggest that accumulation of uremic toxins induce DNA damage. The hemodialysis treatment seems to change the DNA damage.     

Reasons for drop in shell-and-tube condenser performance when replacing R22 with zeotropic mixtures. Part 2: investigation of mass transfer resistance effects

Detailed calculations of condensation outside a column of horizontal smooth tubes have been carried out in order to investigate the influence of mass transfer resistance for a zeotropic refrigerant mixture. Diffusive transport is calculated locally in both phases. Calculation results show that mass transfer resistance in the gas phase reduces heat transfer by 10–20% for a binary mixture with a glide similar to that of R407C.The decrease in heat transfer due to poor mixing in the condensate is from 15 to 65% for the conditions investigated; the lower the duty, the greater the decrease. Results show that if assuming mixing in the condensate by diffusion only, the degrees of mixing and the duty dependency are similar to results in earlier work where calculations were matched to experimental data. Diffusion is likely to be the dominant mixing mechanism in the condensate, and the mixing is poor under certain conditions, which might explain the drop in condenser performance for some heat pump applications.     

Perspective of webometrics

Since the mid-1990s has emerged a new research field, webometrics, investigating the nature and properties of the Web drawing on modern informetric methodologies. The article attempts to point to selected areas of webometric research that demonstrate interesting progress and space for development as well as to some currently less promising areas. Recent investigations of search engine coverage and performance are reviewed as a frame for selected quality and content analyses. Problems with measuring Web Impact Factors (Web-IF) are discussed. Concluding the article, new directions of webometrics are outlined for performing knowledge discovery and issue tracking on the Web, partly based on bibliometric methodologies used in bibliographic and citation databases. In this framework graph theoretic approaches, including path analysis, transversal links, weak ties and small-world phenomena are integrated.     

Spreading dynamics of a functionalized polymer latex

Functionalized polymer nanoparticles are used as binders for inorganic materials in everyday technologies such as paper and coatings. However, the functionalization can give rise to two opposing effects: It can promote adhesion via specific interactions to the substrate, but a high degree of functionalization can also hamper spreading on substrates. Here, we studied the spreading kinetics of individual functionalized vinyl acetate-co-ethylene polymer nanoparticles on inorganic substrates by atomic force microscopy (AFM) imaging. We found that the kinetics underwent a transition from a fast initial regime to a slower regime. The transition was independent of functionalization of the particles but depended on the wettability of the substrate. Furthermore, the transition from the fast regime to the slow regime occurred at a size-dependent contact angle, leading to a h ～ a(3/2) scaling dependence between the height (h) and the width (a) of the spreading particles. Thereafter, spreading continued on a slower time scale. In the slow regime, the kinetics was blocked by a high degree of functionalization. We interpret the observations in terms of a nanoscale stick-slip transition occurring at interface stress around 6 kPa. We develop models that describe the scaling relations between the particle height and width on different substrates.     

Influences of Manufacturing-Related Microstructural Variations on Fatigue in Carbide-Rich Tool Steels

In cold-work applications, tool steels with high carbide contents are used as cutting and stamping tools. The tool service life is limited by wear resistance and fatigue strength. The relationship between manufacturing-related microstructural influences and fatigue strengths of tool steels has not yet been adequately investigated. To investigate these influences on high-cycle fatigue (HCF) strength (N_G = 10⁷), rotating bending tests are performed on AISI D2 and AISI M2/M3. Raw materials are produced by conventional ingot casting and subsequent hot working (HW) as well as in a powder metallurgy (PM) process with hot isostatic pressing (HIP) and forging. Herein, a statistically validated correlation of process-related defect size and the resulting fatigue strength is presented. Both PM steels show significantly higher HCF strength than the HW steels. Critical defects in PM appear to be exclusively small oxide inclusions. In contrast, fatigue cracks in HW are typically initiated by the fracture of large, blocky eutectic carbides. The main factor influencing HCF strength is defect size. Other critical features of the microstructure include matrix hardness, circularity, and defect type. Improvements in fatigue strength can be obtained by reducing the size of fracture mechanical defects, inclusions for PM, and eutectic carbides for HW microstructures.