The effect of dispersed reactive metal oxides on the oxidation resistance of nickel-20 Wt pct chromium alloys

Nickel-20 wt pet chromium alloys containing ThO₂, Y₂O₃, La₂O₃, Al₂O₃ and Li₂O, as prepared by the mechanical alloying technique, were examined for isothermal and cyclic oxidation resistance in dry air at 1000, 1100 and 1200°C. TDNiCr, a commercial electrical heating element alloy (Com Ni-20Cr) and a laboratory melted alloy⁹Lab Ni-20Cr) were also tested. It was found that Y₂O₃, La₂O₃, Al₂O₃ and ThO₂ dispersoids markedly increased both isothermal and cyclic oxidation resistance compared to Lab Ni-20Cr at all temperatures; in contrast Li₂O additions gave no improvement in protection. Com Ni-20Cr was in between Lab Ni-20Cr and the Y₂O₃, A1₂O₃ and ThO₂ containing alloys in both cyclic and isothermal oxidation performance. A mechanism based on alterations in the defect structure of Cr₂O₃ is proposed to explain these dispersed oxide effects on isothermal oxidation behavior. It is based on a reduction in cation transport rates which in turn alter the rate of oxide growth. ThO₂-containing alloys fabricated by the mechanical alloying technique were found to have oxidation resistance fully equal to commercial TDNiCr. Com Ni-20Cr performed better than Lab Ni-20Cr, but not as well as TDNiCr.     

Mercury embrittlement of age-hardened cu-1.9wt Pct cobalt and Cu-3.6 wt Pct Titanium

The embrittlement of age-hardened Cu-1.9 wt pct Co and Cu-3.6 wt pct Ti by mercury was investigated at room temperature. The embrittlement effect on alloys subjected to different aging conditions is correlated with slip mode and precipitate morphology. Copper-cobalt failures in mercury occurred at a stress above conventional yield strength, but below the ultimate tensile strength. The solution-treated condition exhibited the greatest loss in fracture strength. Here, the slip lines were distinct and heterogeneous, while in aged samples, they were diffuse and homogeneous. Heterogeneous slip results in large stress concentrations which can account for the greater embrittlement in the solution-treated structure. In copper-titanium, all failures in mercury occurred in a relatively narrow stress band of 52 to 66 ksi, independent of the state of aging. The yield strength attainable in air ranged from 40 to 98 ksi. In those samples which were aged to form coherent precipitates, failure in mercury occurred below the conventional yield stress. It is thus concluded that the mode of slip and yield strength do not appear to influence significantly the fracture characteristics of copper-titanium in a liquid mercury environment. Formerly Graduate Student, Department of Metallurgy and Materials Sciences, New York University, Bronx, N. Y. This paper is based upon a thesis submitted by H. T. MICHELS in partial fulfillment of the requirements of the degree of Doctor of Philosophy at New York University.     

Telephone booster sessions for optimizing smoking cessation for patients in rehabilitation centers.

Smokers with smoking-related diseases who are hospitalized in rehabilitation centers should be offered smoking cessation. This is the first study evaluating whether telephone booster sessions after intensive inpatient treatment are an effective strategy. The present study was conducted in 13 rehabilitation centers for somatic disorders as a prospective multicenter study with a randomized treatment-control group design. We compared abstinence rates after hospital discharge from treatment that included a group smoking cessation program with (treatment group) and without telephone booster sessions (control group). Data from 290 smokers were analyzed. After 6 and 12 months the treatment group achieved abstinence rates twice as high as those of the control group. Men profited more from telephone booster sessions than did women. Results indicated that telephone booster sessions were highly effective (even) after an inherently intensive group program during a hospital stay. Further research should focus on the special needs of women receiving telephone counseling.     

Unexplained site variance in machine strength grading of Norway spruce structural timber

The aim of the study was to assess site effects in terms of unexplained site variance in machine strength grading of Norway spruce structural timber. The site effects were estimated for grading based on axial resonance frequency and timber length, and for grading based on dynamic modulus of elasticity. Timber was collected from 14 sites in Norway, and linear mixed models were developed based on 1188 boards. The study showed that strength grading based on axial resonance frequency and timber length leaves out effects of site that are related to altitude, latitude and site index. The variance could be reduced when the grading was based on dynamic modulus of elasticity. For both grading methods, the site effects were smaller for bending strength than for modulus of elasticity and density. Major parts of the site effects were explained by mass density, and simulations showed that it is possible to fulfil the requirements of the strength classes with a higher yield when the sorting is based on a combination of exclusion by mass density and exclusion by the frequency-based indicating property.     

Blackcurrant pomace from juice processing as partial flour substitute in savoury crackers: dough characteristics and product properties

Berry pomace is a by‐product of juice processing that, after drying and milling, may be used as an ingredient in cereal‐based products. This, on the one hand, not only reduces losses of edible raw material components, but also increases the nutritional value of the target food because of its high dietary fibre and bioactive compounds content. By using savoury crackers as model, this study analyses how a partial flour replacement by blackcurrant pomace (levels: 10%, 20% or 30%) affects physical properties of the respective dough (dynamic rheology in simulated baking, extensibility and adhesiveness) and characteristics of the baked product (colour, texture and sensory properties). Pomace addition significantly affected both systems. By considering the high moisture absorption capacity of this material through water level adaptation in formulations and by only substituting gluten‐free flour (which led to a constant gluten content), it is demonstrated that even a flour replacement of up to 30% leads to acceptable products. A restrained protein development was observed in pomace containing dough, leading to a lower extensibility, and to reduced volume increase and lower breaking force after baking. In contrast, dough handling and sensory acceptance were not corrupted by pomace application even though colour of the final product was changed to a great extent.     

Nanomaterial Transformations in the Environment: Effects of Changing Exposure Forms on Bioaccumulation and Toxicity

In the environment, nanomaterials (NMs) are subject to chemical transformations, such as redox reactions, dissolution, coating degradation, and organic matter, protein, and macromolecule binding, and physical transformations including homo or heteroagglomeration. The combination of these reactions can result in NMs with differing characteristics progressing through a functional fate pathway that leads to the formation of transformed NM functional fate groups with shared properties. To establish the nature of such effects of transformation on NMs, four main types of studies are conducted: 1) chemical aging for transformation of pristine NMs; 2) manipulation of test media to change NM surface properties; 3) aging of pristine NMs water, sediment, or soil; 4) NM aging in waste streams and natural environments. From these studies a paradigm of aging effects on NM uptake and toxicity can be developed. Transformation, especially speciation changes, largely results in reduced potency. Further reactions at the surface resulting in processes, such as ecocorona formation and heteroagglomeration may additionally reduce NM potency. When NMs of differing potency transform and enter environments, common transformation reaction occurring in receiving system may act to reduce the variation in hazard between different initial NMs leading to similar actual hazard under realistic exposure conditions.     

Photoderivatized polymer thin films at quartz crystal microbalance surfaces: sensors for carbohydrate-protein interactions

Photoderivatized polymer-coated gold surfaces have been developed following a perfluorophenylazide-based double ligation strategy. Gold-plated quartz crystal microbalance (QCM) crystals were initially covalently functionalized with a monolayer of poly(ethylene glycol) (PEG), using photo- or thermolytic nitrene formation and insertion. The polymer surfaces were subsequently used as substrates for photoinsertion of carbohydrate-derivatized photoprobes, yielding different recognition motifs for selective protein binding. The resulting robust and biocompatible sensor surfaces were applied to a flow-through QCM instrument for monitoring lectin-carbohydrate interactions in real time. The results clearly show the predicted lectin selectivity, demonstrating the applicability of the approach.