The Nature of a Hard Protein Corona Forming on Quantum Dots Exposed to Human Blood Serum

Biological responses of cells and organisms to nanoparticle exposure crucially depend on the properties of the protein adsorption layer (“protein corona”) forming on nanoparticle surfaces and their characterization is a crucial step toward a deep, mechanistic understanding of their build‐up. Previously, adsorption of one type of model protein on nanoparticles was systematically studied in situ by using fluorescence correlation spectroscopy. Here, the first such study of interactions is presented between water‐solubilized CdSe/ZnS quantum dots (QDs) and a complex biofluid, human blood serum. Despite the large number of proteins in serum, a protein layer of well‐defined (average) thickness forming on QD surfaces is observed. Both the thickness and the apparent binding affinity depend on the type of QD surface ligand. Kinetic experiments reveal that the protein corona formed from serum is irreversibly bound, whereas the one formed from human serum albumin was earlier observed to be reversible. By using sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and mass spectrometry, the most abundant serum proteins contributing to the formation of a hard corona on the QDs are identified.     

Developing a product–service system through a productisation strategy: a case from the 3PL industry

A Product–Service System (PSS) is created by combing a tangible product and an intangible service into one integrated offering. Thus, a PSS can be achieved by a production company adding intangible services to a product using a servitisation strategy or by a service company adding a tangible product to a service by means of a productisation strategy. The focus of this paper is on the latter. Our work demonstrates a significant gap in the literature in this area. To address this, we adapt an existing PSS conceptual framework as a means to identify the driving and restraining forces considered by a service company as it explored the possibility of pursuing a PSS productisation strategy. The conceptual framework is applied in an exploratory case study with a 3PL service provider. Application of the framework reveals new driving and restraining forces not previously discussed in the literature. Furthermore, it allows a preliminary quantification of the driving and restraining forces using a force field analysis approach. Our work contributes towards the expansion of the empirical knowledge base in the area of PSS.     

Challenges of evolvable hardware: past,present and the path to a promising future

Nature is phenomenal. The achievements in, for example, evolution are everywhere to be seen: complexity, resilience, inventive solutions and beauty. Evolvable Hardware (EH) is a field of evolutionary computation (EC) that focuses on the embodiment of evolution in a physical media. If EH could achieve even a small step in natural evolution’s achievements, it would be a significant step for hardware designers. Before the field of EH began, EC had already shown artificial evolution to be a highly competitive problem solver. EH thus started off as a new and exciting field with much promise. It seemed only a matter of time before researchers would find ways to convert such techniques into hardware problem solvers and further refine the techniques to achieve systems that were competitive with or better than human designs. However, 15 years on—it appears that problems solved by EH are only of the size and complexity of that achievable in EC 15 years ago and seldom compete with traditional designs. A critical review of the field is presented. Whilst highlighting some of the successes, it also considers why the field is far from reaching these goals. The paper further redefines the field and speculates where the field should go in the next 10 years.     

Triacylglycerols and Polar Lipids in Cow and Goat Milk are Differentially Affected by Various Lipid Supplemented Diets

This study characterizes milk triacylglycerol (TAG) and polar lipid (PL) fractions from cows and goats fed various lipid supplements modulating milk fat content. Twelve Holstein cows and 12 Alpine goats, at 86 ± 24.9 and 61 ± 1.8 days in milk, respectively, are allocated to one of 4 groups to receive diets supplemented with either corn oil [5% dry matter intake (DMI)] plus wheat starch (COS), marine algae powder (MAP; 1.5% DMI) or hydrogenated palm oil (HPO; 3% DMI), or a no-added-lipid control diet (CTL), according to a 4 × 4 Latin square design with 28 d experimental periods. Milk TAG and PL contents are determined by liquid chromatography-mass spectrometry (LC-MS). Multivariate analysis and ANOVA demonstrate major between-species differences in diet effects. In cows, COS specifically increases TAG 54:3 and 54:4 associated with milk fat depression (MFD), and increases the sum of phosphatidylcholines (PC) and phosphatidylinositols (PI). In addition to causing a MFD, MAP diet increases long-chain polyunsaturated TAG in both species, with higher magnitude in cows than in goats, and decreases the sum of PI in goats. HPO increases TAG 52:1 and the sum of PI in cows, but not in goats. Practical applications: Feed strategies can quickly and efficiently modulate the ruminant milk fat production and composition to improve nutritional quality for consumers. Certain starch-rich diets supplemented with polyunsaturated fatty acids (PUFA)-rich vegetable oils and diets supplemented with marine products (long-chain PUFA) reduce milk fat secretion and modify the milk fatty acid (FA) profile in cows, but not—or less so—in goats. Advanced analysis of both the TAG and PL fractions of milk fat is required to unravel these differences in lipid metabolism between cows and goats fed various lipid-supplemented diets. This study brings new insight on using nutritional strategies to control milk lipid composition according to ruminant species.     

The effect of crown shape on the reflectance of coniferous stands

The Kuusk-Nilson forest reflectance model was used to study the effect of crown shape on the reflectance of Scots pine and Norway spruce stands. In the first part of the study, we examined spruce and pine stands with an age range of 20-100 years and compared their simulated hemispherical-directional reflectance factors (HDRFs) at nadir in red (661 nm), NIR (838 nm) and MIR (1677 nm) when crowns were modeled as ellipsoids or cones. In all the cases, when a stand was modeled with conical crowns, it had a smaller reflectance factor than the same stand with ellipsoidal crowns.To analyze the sensitivity of HDRF on crown shape, in the second part of the study we simulated the angular distributions of HDRF of two pine stands with different leaf area index (LAI) and canopy closure values at 661 nm assuming four different crown shapes (cone, cylinder, ellipsoid, and cylinder bottom, cone top) and separated the components forming the HDRF. Considerable difference in the HDRF between the four crown shapes was observed: The larger the crown volume, the higher the canopy reflectance at similar LAI and canopy closure. A comparison of the two stands revealed that in denser stands (with a higher canopy closure) single scattering from tree crowns was responsible for the difference in HDRF between the different crown shapes, whereas in stands with a smaller canopy closure the single scattering from ground dominated the HDRF. Finally, the role of crown shape for the retrieval of LAI by inversion from remotely sensed data is discussed.     

The Filtration Properties of Atropa belladonna Plant Cell Suspensions; Effects of Hydrodynamic Shear and Elevated Carbon Dioxide Levels on Culture and Filtration Parameters

The filtration properties of Atropa belladonna plant cell suspensions cultured at different bioreactor stirrer speeds and gas-phase carbon dioxide levels were measured. Cell cake compressibility did not vary significantly with culture time, shear intensity or carbon dioxide concentration. Average cell cake permeability decreased by c. 70% with increasing stirrer speeds between 400 and 1000 rpm, and could be correlated with concomitant reductions in cell aggregate size. Permeability was more responsible than other culture parameters, such as growth, cell membrane integrity and protein release, to levels of hydrodynamic energy dissipation in the range 10⁶–10⁹ J m⁻³. Cell cake permeability was significantly affected by carbon dioxide levels of 10 and 15%, but not 2%. Average permeability at 15% CO₂ was reduced by c. 50% compared with the air-sparged control culture, even though aggregate size, morphological characteristics and filtered cake compressibility were unaltered. A distinctive pattern of permeability change over the course of the cultures was observed when the reactor conditions were not inhibitory to growth; however, this pattern was destroyed at medium-to-high shear levels and high carbon dioxide concentrations. © 1997 SCI.     

Determination of <Emphasis Type="Italic">Bacillus cereus</Emphasis> Emetic Toxin in Food Products by Means of LC–MS²

Cereulide is the heat-stable toxin produced by certain strains of Bacillus cereus. It is the main virulence factor of emetic B. cereus strains, which causes the emetic food poisoning syndrome, including rare fatal cases of food intoxications. Due to presumably low intoxication doses, a sensitive, specific, and robust technique is needed for its detection. In 2002, a LC–MS method was developed which allowed absolute quantification of cereulide using valinomycin as standard. This study describes the validation, according to the Commission Decision 2002/657/EC, of the LC–MS2 method, a tandem mass spectrometry technique, which guarantees lower detection limit and higher specificity. The LC–MS2 method, calibrated with valinomycin, was validated in rice and tested on various matrices (i.e., red beans, spices, and chili con carne) containing cereulide. The process combines a simple extraction step from the food matrix followed by LC–MS2 analysis and detection by ion trap mass spectrometer. The detection limit for cereulide in rice was 0.5 ng eq/g, which is 20 to 2,500 times lower than currently understood intoxicative doses between 10 and 1.280 ng/g previously reported for cereulide. The validated method was specific, sensitive, repeatable, and reproducible with recoveries ranging from 77% to 101%.     

Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways

Background

Exposure to fine ambient particulate matter (PM) has consistently been associated with increased morbidity and mortality. The relationship between exposure to ultrafine particles (UFP) and health effects is less firmly established. If UFP cause health effects independently from coarser fractions, this could affect health impact assessment of air pollution, which would possibly lead to alternative policy options to be considered to reduce the disease burden of PM. Therefore, we organized an expert elicitation workshop to assess the evidence for a causal relationship between exposure to UFP and health endpoints.

Methods

An expert elicitation on the health effects of ambient ultrafine particle exposure was carried out, focusing on: 1) the likelihood of causal relationships with key health endpoints, and 2) the likelihood of potential causal pathways for cardiac events. Based on a systematic peer-nomination procedure, fourteen European experts (epidemiologists, toxicologists and clinicians) were selected, of whom twelve attended. They were provided with a briefing book containing key literature. After a group discussion, individual expert judgments in the form of ratings of the likelihood of causal relationships and pathways were obtained using a confidence scheme adapted from the one used by the Intergovernmental Panel on Climate Change.

Results

The likelihood of an independent causal relationship between increased short-term UFP exposure and increased all-cause mortality, hospital admissions for cardiovascular and respiratory diseases, aggravation of asthma symptoms and lung function decrements was rated medium to high by most experts. The likelihood for long-term UFP exposure to be causally related to all cause mortality, cardiovascular and respiratory morbidity and lung cancer was rated slightly lower, mostly medium. The experts rated the likelihood of each of the six identified possible causal pathways separately. Out of these six, the highest likelihood was rated for the pathway involving respiratory inflammation and subsequent thrombotic effects.

Conclusion

The overall medium to high likelihood rating of causality of health effects of UFP exposure and the high likelihood rating of at least one of the proposed causal mechanisms explaining associations between UFP and cardiac events, stresses the importance of considering UFP in future health impact assessments of (transport-related) air pollution, and the need for further research on UFP exposure and health effects.