Nanoindentation of single pulp fibre cell walls

Unrefined chemical pulps of bleached and unbleached softwood (Scots pine, Pinus sylvestris) and hardwood (Eucalyptus, Eucalyptus globulus) were subjected to indentation tests using a nanoindenter equipped with an AFM scanner. Tests on unbleached pulps revealed no difference in hardness values between softwood and hardwood, but bleaching treatment decreased the hardness values of both pulps. Indentation modulus of 12 GPa was observed for unbleached softwood pulps, which is 25% higher than unbleached hardwood pulps. Bleaching treatment again decreased the indentation modulus of the softwood pulps, whereas it slightly increased the indentation modulus of the hardwood pulps. After bleaching and drying processes, only negligible difference was observed in cell wall mechanical properties (hardness and indentation modulus) between hardwood and softwood pulps. This study is based on latewood pulp fibres.     

Cellular toxicity of carbon-based nanomaterials

The cellular toxicity of carbon-based nanomaterials was studied as a function of their aspect ratio and surface chemistry. These structures were multiwalled carbon nanotubes, carbon nanofibers, and carbon nanoparticles. Their toxicity was tested in vitro on lung tumor cells. Our work clearly indicated that these materials are toxic while the hazardous effect is size-dependent. Moreover, cytotoxicity is enhanced when the surface of the particles is functionalized after an acid treatment.     

Insights into photovoltaic properties of ternary organic solar cells from phase diagrams

The efficiency of ternary organic solar cells relies on the spontaneous establishment of a nanostructured network of donor and acceptor phases during film formation. A fundamental understanding of phase composition and arrangement and correlations to photovoltaic device parameters is of utmost relevance for both science and technology. We demonstrate a general approach to understanding solar cell behavior from simple thermodynamic principles. For two ternary blend systems we construct and model phase diagrams. Details of EQE and solar cell parameters can be understood from the phase behavior. Our blend system is composed of PC₇₀BM, PBDTTT-C and a near-infrared absorbing cyanine dye. Cyanine dyes are accompanied by counterions, which, in a first approximation, do not change the photophysical properties of the dye, but strongly influence the morphology of the ternary blend. We argue that counterion dissociation is responsible for different mixing behavior. For the dye with a hexafluorophosphate counterion a hierarchical morphology develops, the dye phase separates on a large scale from PC₇₀BM and cannot contribute to photocurrent. Differently, a cyanine dye with a TRISPHAT counterion shows partial miscibility with PC₇₀BM. A large two-phase region dictated by the PC₇₀BM: PBDTTT-C mixture is present and the dye greatly contributes to the short-circuit current.     

Flavonoid-related modulators of multidrug resistance: synthesis, pharmacological activity, and structure-activity relationships

A series of 28 flavonoid derivatives containing a N-benzylpiperazine chain have been synthesized and tested for their ability to modulate multidrug resistance (MDR) in vitro. At 5 microM, most compounds potentiated doxorubicin cytotoxicity on resistant K562/DOX cells. They were also able to increase the intracellular accumulation of JC-1, a fluorescent molecule recently described as a probe of P-glycoprotein-mediated MDR. This suggests that these compounds act, at least in part, by inhibiting P-glycoprotein activity. As in other studies, lipophilicity was shown to influence MDR-modulating activity but was not the only determinant. Diverse di- and trimethoxy substitutions on N-benzyl were examined and found to affect the activity differently. The most active compounds had a 2,3, 4-trimethoxybenzylpiperazine chain attached to either a flavone or a flavanone moiety (13, 19, 33, and 37) and were found to be more potent than verapamil.     

The trigger system of the first CMS tracker beam tests

The trigger for the first compact muon solenoid (CMS) tracking beam tests is a dedicated system for analog multiplexed front-end electronics. With this first generation of electronics dedicated to CMS tracker detectors, some new specific development was necessary to read it with a multicrate distributed data acquisition (DAQ) system. The goal of this development was to reach a high scalability of experiment subsystems and a good robustness for test beams. Each subsystem had to be independent from the others, both from the hardware and software point of view. Remote control software for this system as well as further monitoring facilities were the required functions of the trigger system     

Nanocomposite Hard Coatings: Deposition Issues and Validation of their Mechanical Properties

The limitations of conventional coatings due to inferior hardness or poor oxidation stability can be overcome by nanocomposite hard coatings such as nc‐TiN/a‐SiN_x, which consists of nanocrystalline TiN and a non‐crystalline tissue phase of SiN_x which are mutually immiscible. The properties of nanocomposite coatings, especially their increased hardness, can be explained by their nanostructure, which leads to a maximum hardness at typically 80 atomic percent of the crystalline phase. We show that enhanced hardness can only be attained when the silicon nitride phase is sufficiently nitrided. The accurate and reliable measurement of the hardness and elastic modulus requires the use of appropriate nanoindentation equipment and a careful tip correction with periodical validation. It is shown that for a correct hardness determination of a few microns thick nanocomposite coatings, an indentation depth of 100 nm is sufficient. The maximum hardness of our nc‐TiN/a‐SiN_x coatings deposited by a hybrid UBM/arc‐PVD process is about 40 GPa. This value represents a global hardness value, due to the nanocomposite structure there may be a local hardness variation of about ±10 %.     

Comparison of the Ca2+-binding properties of human recombinant calretinin-22k and calretinin

Calretinin-22k (CR-22k) is a splice product of calretinin (CR) found specifically in cancer cells, and possesses four EF-hands and a differently processed C-terminal end. The Ca2+-binding properties of recombinant human calretinin CR-22k were investigated by flow dialysis and spectroscopic methods and compared with those of CR. CR possesses four Ca2+-binding sites with positive cooperativity (nH = 1.3) and a [Ca2+]0.5 of 1.5 microM, plus one low affinity site with an intrinsic dissociation constant (K'D) of 0.5 mM. CR-22k contains three Ca2+-binding sites with nH of 1.3 and [Ca2+]0.5 of 1.2 microM, plus a low affinity site with K'D of 1 mM. All the sites seem to be of the Ca2+-specific type. Limited proteolysis and thiol reactivity suggest that that the C terminus of full-length CR, but not of CR-22k, is in close proximity of site I leading to mutual shielding. Circular dichroism (CD) spectra predict that the content of alpha-helix in CR and CR-22k is similar and that Ca2+ binding leads to very small changes in the CD spectra of both proteins. The optical properties are very similar for CR-22k and CR, even though CR-22k possesses one additional Trp at the C-terminal end, and revealed that the Trp residues are organized into a hydrophobic core in the metal-free proteins and become even better shielded from the aqueous environment upon binding of Ca2+. The fluorescence of the hydrophobic probe 2-p-toluidinylnaphtalene-6-sulfonate is markedly enhanced by the two proteins already in the absence of Ca2+ and is further increased by binding of Ca2+. The trypsinolysis patterns of CR and CR-22k are markedly dependent on the presence or absence of Ca2+. Together, our data suggest the presence of an allosteric conformational unit encompassing sites I-III for CR-22k and I-IV for CR, with a very similar conformation and conformational changes for both proteins. In the allosteric unit of CR, site IV is fully active, whereas in CR-22k this site has a 80-fold decreased affinity, due to the decreased amphiphilic properties of the C-terminal helix of this site. Some very specific Ca2+-dependent conformational changes suggest that both CR and CR-22k belong to the "sensor"-type family of Ca2+-binding proteins.     

A double-blind study of paroxetine, fluoxetine, and placebo in outpatients with major depression

Human milk has a higher concentration of nucleotides than bovine milk which is the source of most infant formulas. As the composition of human milk is considered the 'gold standard,' an increasing number of infant formulas are supplemented with nucleotides. This review summarises the biology of human milk nucleotides and evaluates the studies which investigated the clinical benefits of feeding infants with nucleotide-supplemented formulas. Although dietary nucleotides have been suggested to have beneficial gastrointestinal and immunological effects, nucleotide-supplemented formula feeding has not been shown to confer the same benefits as breast feeding, and randomised controlled trials have yet to prove that healthy term infants fed nucleotide-supplemented formulas compared to those fed nonsupplemented formulas, have accelerated physical growth and neurological development, better growth and development of their gastrointestinal tract resulting in improved digestive and absorptive functions, enhanced development of their immune system resulting in increased resistance to infection and lower bacterial and viral infection rates during infancy, and a more favourable intestinal microflora associated with a lower rate of infectious diarrhoea. However, a randomised controlled trial has reported that term infants with severe intrauterine growth retardation do have better catch-up growth with nucleotide supplementation. The hypothesis that nucleotides are semi-essential nutrients needs to be further studied, in particular in the presence of prematurity, fetal growth retardation, intestinal injury and limited nutrient intake. As no deleterious effects have been reported with the use of nucleotide-supplemented formulas, the first of which was introduced over 30 years ago, such products are considered safe when nucleotides are supplemented to an amount equivalent to the free nucleotide concentration of human milk. More basic and clinical research studies are awaited to further define the biology and role of human milk nucleotides, and to critically assess the potential benefits and appropriate level of nucleotide supplementation of infant formula.     

The H<Subscript>2</Subscript> plasma treatment of silver contacts: Impact on wire-bonding performance

The ultrasonic wire-bonding performance on Ag bond pads is limited by the presence of oxides and organic contaminants. These contaminations act as lubricants during wire bonding. They reduce the interfacial friction and decrease the heat dissipation between the two contacting materials, leading to bad bond quality. Plasma processes have proven to be a valuable tool for eliminating such contaminations and boosting wire-bonding performance. We present investigations of the effects of H₂ plasma on oxidized silver films by photoelectron spectroscopy and quartz-crystal microbalance (QCM) measurements. The H₂ plasma treatment of Ag bond pads is not a classical surface-cleaning process. It is a bulk process, and it induces a reduction of silver oxide and recrystallization. The high mass transport caused by large changes in density during reduction leads to the formation of (111)-terminated regions at the surface. This densely packed termination can account for the apparent passivating effect of H₂ plasmas on Ag bond pads, which allows for long-term storage in ambient atmosphere without deteriorating bonding performance.