Graphene-stabilized copper nanoparticles as an air-stable substitute for silver and gold in low-cost ink-jet printable electronics

Metallic copper nanoparticles were synthesized by a bottom-up approach, and in situ coated with protective shells of graphene in order to get a metal nanopowder of high air stability and chemical inertness. Using an amphiphilic surfactant, a water-based copper nanocolloid could be prepared and successfully printed onto a polymer substrate by conventional ink-jet printing using household printers. The dried printed patterns exhibited strong metallic gloss and an electrical conductivity of >1?S?cm(-1) without the need for a sintering or densification step. This conductivity currently limits use in electronics to low current application or shielding and decorative effects. The high stability of graphene-coated copper nanoparticles makes them economically a most attractive alternative to silver or gold nanocolloids, and will strongly facilitate the industrial use of metal nanocolloids in consumer goods.     

Mediators of a coping and communication-enhancing intervention and a supportive counseling intervention among women diagnosed with gynecological cancers.

The authors evaluated mechanisms of change for a coping and communication-enhancing intervention (CCI) and supportive counseling (SC). They proposed that the effects of CCI on depressive symptoms would be mediated by psychological processes targeted by CCI, namely increases in the following: positive reappraisal, acceptance, planful problem solving, attempts to understand emotional reactions to cancer, emotional expression, seeking of emotional and instrumental support, and self-esteem. The authors hypothesized that the effects of SC on depressive symptoms would be mediated by the processes encouraged by SC, in this case increases in the following: expression of emotions, attempts to understand emotional reactions to cancer, and self-esteem. Three hundred fifty-three women were randomized to a CCI, SC, or usual care control group and completed measures at preintervention and 3, 6, and 9 months later. The effects of CCI were fully mediated by positive reappraisal, problem solving, and self-esteem and partially mediated by emotional expression. The effects of SC were partially mediated by positive reappraisal. These findings provide support for hypothesized mediators for CCI. The authors were less able to identify mediators for SC. Future research might benefit from identifying SC mediators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using the internet to assist smoking prevention and cessation in schools: A randomized, controlled trial.

Objective: To evaluate the impact of a classroom-based, Web-assisted tobacco intervention addressing smoking prevention and cessation with adolescents. Design: A two-group randomized control trial with 1,402 male and female students in grades 9 through 11 from 14 secondary schools in Toronto, Canada. Participants were randomly assigned to a tailored Web-assisted tobacco intervention or an interactive control condition task conducted during a single classroom session with e-mail follow-up. The cornerstone of the intervention was a five-stage interactive Web site called the Smoking Zine (http://www.smokingzine.org) integrated into a program that included a paper-based journal, a small group form of motivational interviewing, and tailored e-mails. Main Outcome Measure: Resistance to smoking, behavioral intentions to smoke, and cigarette use were assessed at baseline, postintervention, and three- and six-month follow-up. Multilevel logistic growth modeling was used to assess the effect of the intervention on change over time. Results: The integrated Smoking Zine program helped smokers significantly reduce the likelihood of having high intentions to smoke and increased their likelihood of high resistance to continued cigarette use at 6 months. The intervention also significantly reduced the likelihood of heavy cigarette use adoption by nonsmokers during the study period. Conclusion: The Smoking Zine intervention provided cessation motivation for smokers most resistant to quitting at baseline and prevented nonsmoking adolescents from becoming heavy smokers at 6 months. By providing an accessible and attractive method of engaging young people in smoking prevention and cessation, this interactive and integrated program provides a novel vehicle for school- and population-level health promotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors Effecting the Performance of Montmorillonite/Magnesium Hydroxide/Poly(propylene) Ternary Composites, 1

A two‐level factorial experimental design was used to examine the combined effects of o‐MMT gallery polarity, surface modification of MDH, MA‐g‐PP and antioxidant addition, together with processing variables, on the burning behaviour and thermal stability of ternary composites based on PP, MDH and o‐MMT. Regression equations highlighted the detrimental effect of o‐MMT intercalants and possible improvement in the dispersion of o‐MMT at higher MDH levels. A polar gallery environment (providing quat OH groups) led to increased char formation, and MA‐g‐PP combined with o‐MMT led to a higher oxidation onset temperature. Addition of o‐MMT to PP/MDH composites can lead to a reduction in the level of MDH required for effective flame retardation.

     

点焊镀锌钢板时电极头部形状对电极失效的影响

利用扫描电镜和X射线能谱等方法分析了在点焊镀锌钢板时电极头部形状对电极失效的影响.结果表明:点焊镀锌钢板时,球形电极的失效主要因素是电极和镀锌板之间局部焊接的断裂发生在电极表面而导致的电极磨损,以及电极和镀锌板表面的锌之间的合金化;截锥形电极的失效除了电极头部的磨损和少量的合金化外,还有电极头部大量的塑性变形.     

Plasmonic‐Radiation‐Enhanced Metal Oxide Nanowire Heterojunctions for Controllable Multilevel Memory

Nanowire memristor devices that display multilevel memory effects are of great interest for high‐density storage, however, numerous challenges remain in fabricating high‐quality, stable memory units. A plasmonic‐radiation‐enhanced technique is introduced in this work for scalably forming nanowire multilevel memory units with superior properties. Femtosecond laser irradiation of gold‐titanium dioxide nanowire‐gold structures results in plasmonic‐enhanced optical absorption in the TiO₂ locally at the metal‐oxide interface. This produces junctions with superior mechanical and electrical contact, and engineers a concentration of charged defects in the TiO₂ near the interface, which enables stable multilevel memory behavior without the need for a traditional electroforming step. The memory units produced display eight‐level current amplification under continuous forward voltage cycles, and can replicate complex multilevel memory sequences without interference between the different multilevel states.     

Distance determination in heterogeneous DNA model systems by pulsed EPR

Many biological systems, especially those based on nucleic acids, are structurally heterogeneous in solution. We demonstrate here the ability to measure multiple distances, of between 2 and 7 nm, from a heterogeneous mixture of double-spin-labeled DNA duplexes. We have constructed a DNA distance ruler based on the attachment of nitroxide spin labels to 2'-amino-modified nucleosides. The distribution of distances between the spin labels was obtained by Tikhonov regularization analysis of the dipolar coupling evolution data measured by using the electron paramagnetic resonance method, pulsed-electron double resonance (PELDOR). Optimization of the conditions and techniques used in the preparation of the samples has allowed us to increase the sensitivity and reduce aggregation artifacts. As a result, we have been able to demonstrate deconvolution of distances from structurally heterogeneous samples and show the limits of the technique by examining data derived from up to five DNA duplexes, in a single mixture, in which the concentration of each species was as low as 5 microM.     

Quantification and modeling of the elimination behavior of ecologically problematic wastewater micropollutants by adsorption on powdered and granulated activated carbon

The adsorption on powdered activated carbon (PAC) of ecotoxic or potentially ecotoxic micropollutants (ten pharmaceuticals, four X-ray contrast media, and eight industrial chemicals) present in a biologically treated municipal wastewater is studied. All but the X-ray contrast media are eliminated with high efficiency at an economically feasible PAC dosage of 10 mg/L. Based on the experimental data, the competition between the background organic matter and the micropollutant for the active sites of the adsorbent is modeled with the help of the adsorption and tracer analysis supported by the Ideal Adsorption Solution Theory. With granulated activated carbon, adsorption isotherms are determined by spiking. Based on these experimental data and modeled parameters, a lay-out of fixed-bed adsorbers may be simulated.     

Determining residence patterns of rainbow trout using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of selenium in otoliths

Toxicological studies are often hampered by concerns of fish residency in the industrial effluent being evaluated. Contaminants in muscle or visceral tissue are useful indicators of recent exposure, but depuration, metabolic transformation, and tissue recompartmentalization of contaminants makes their use as temporal markers tenuous. Otoliths are metabolically stable and can provide temporal resolution for exposure to some elements that are incorporated into their calcified structure, including the divalent cations Sr, Zn, and Mn. Here we provide the first determinations of selenium, an anion in biological systems, in the otoliths of rainbow trout captured from a site receiving runoff with elevated selenium from a coal mine operation. Concentrations of selenium in annual growth zones of otoliths suggest that fish from the mine-impacted system are recent immigrants from nearby reference streams not receiving selenium-bearing effluent.     

Bone tissue reaction to Ti–48Al–2Cr–2Nb (at.%) in a rodent model: a preliminary SEM study

A variety of metals have been used to replace the skeletal framework of human beings. Gamma titanium aluminide (γTiAl) has been recently developed as a prospective material for turbine applications. In this preliminary study, the potential of γTiAl as a biomaterial was evaluated using an in vivo rat model. Sprague–Dawley rats were implanted with γTiAl cylinders in the femur and observed for an experimental period lasting up to 180 days. The rats were sacrificed after periods of 45, 90 and 180 days. The femurs with the γTiAl implants were extracted and examined using scanning electron microscopy (SEM). Normal bone growth processes were observed as early as 45 days after γTiAl cylinder implantation. No signs of rejection of the implant metal were observed. In fact, a layered bone growth was observed on the implant metal surface. The bone–metal interface showed signs of tissue growth from original bone to the metal surface. γTiAl appears to elicit a normal bone tissue reaction and hence, has potential as a metallic implant material.