The Effect of Pressing Parameters on the Mechanical Properties of Plastic Bonded Explosives

Quasi‐static, uniaxial mechanical properties were measured for a series of PBX 9501 parts that were compacted using a permutation of various pressing parameters. Results were analyzed in terms of specimen density as well as pressing parameters. These data led to a second set of tests where PBX 9501 parts were compacted using various dwell times and temperatures, all other pressing parameters being held constant. Quasi‐static tensile data for these parts indicated that for the given range of parameters and specimen densities, the compaction temperature has a larger effect on the mechanical properties than does the dwell time. Moreover, for the range of parameters used, higher compaction temperatures and lower dwell times gave the compacted part more strength and toughness. Desired mechanical characteristics may be achieved by the appropriate selection of pressing conditions.     

The effect of hybrid nanoparticle additives on epoxy‐nanocomposite behavior and morphology

Amine modified polyhedral oligomeric silsesquioxane (POSS‐NH₂) was used to modify sodium montmorillonite (MMT) nanoclays for improved dispersion in epoxy resin. The dispersion of the clay particles was inspected using scanning electron microscopy, energy dispersive spectroscopy (EDS) and X‐Ray diffraction and the thermal properties compared using differential scanning calorimetry (DSC) and thermogravametric analysis. The introduction of the amine‐POSS was found to have a positive effect on the dispersion of the MMT clays and prevented agglomeration. The absence of clay agglomerates lead to an increase in glass transition temperature (T_g) from 44°C in the samples with the untreated clay up to 54°C in the samples with 10% additional POSS‐NH₂. The addition of POSS‐NH₂ initial increase of the weight loss (T_{d 5%}) but slowed down the rate of degradation due to the formation of an inert silica layer and eventually leading to an increased charyield. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Weinbrand, seine Verf?lschungen und deren Nachweis

Ohne Zusammenfassung     

Thermophysical properties of mixed oxide fuel and stainless steel type 316 for use in transition phase analysis

For use in transition phase analysis, we have obtained thermodynamic and transport properties of mixed oxide fuel and stainless steel type 316, over a very wide range of temperatures. The majority of the thermodynamic properties for these materials in their solid and liquid states are based on either actual experimental data or extrapolation of low temperature data. However, a number of properties for these materials in the vapor state are based on very limited and scarce data. These properties include saturation vapor pressure, latent heat of vaporization and specific volume of saturated vapor. Due to complete lack of experimental data, a number of other properties such as specific heats, heat of vaporization (especially for stainless steel), transport properties, and the properties at the critical state had to be estimated by use of generally reliable empirical relations. It is recommended that efforts be initiated to obtain experimental data for these materials in the vapor state to verify both existing empirical relations and the relationships that are obtained here based on theoretical analyses.     

Missed MI diagnosis

An extracellular lipase (Lip)-encoding gene from Streptomyces albus G has been cloned and sequenced. It encodes a Lip with 82% sequence identity to another previously cloned Lip from a Streptomyces species not closely related. These two sequences can be aligned with 33% identity to the sequence of Lip1 from the antarctic psychrotroph Moraxella TA144 [G. Feller et al., Nucleic Acids Res. 18 (1990) 6431]. An alignment of the three sequences revealed amino-acid substitutions which might be responsible for the greater thermal stability of the Streptomyces lipases. The presence of this lip gene family in several members of the Streptomyces genus was also shown.     

Reading the fine print of the human genome

It is our belief that the genomic annotations and data formats will eventually converge into more standardized forms. At such time, an effective data retrieval confluence can be attained and elaborate annotation heuristics may not be necessary. This has begun to happen already with the LocusLink project where several databases are linked to provide a "one-stop-shopping" resource for genomic, genetic, and phenotypic information tied together by a single gene locus identifier. Overall, we were able to identify a number of clones that could serve as new cancer markers (whether they are suitable is a question to be answered in the wet lab). The moral of the story is that predictions of the end of science are rarely (if ever) correct. While some of the easier biological questions may have already been answered with the availability of the "complete" human genome, the genome contains many more answers for which we need to find the right questions. Focusing on the difficult, less understood areas is one way to ensure that we are vigilantly attempting to take advantage of the richness and depth of information available in the human genome.     

Nanostructures and lithium electrochemical reactivity of lithium titanites and titanium oxides: A review

Being inherently safe and chemically compatible with the electrolyte, titanium oxide-based materials, including both Li-titanites and various TiO₂ polymorphs, are considered alternatives to carbonaceous anodes in Li-ion batteries. Given the commercial success of the spinel lithium titanites, TiO₂ polymorphs, in particular in nanostructured forms, have been fabricated and investigated for the applications. Nanostructuring leads to increased reaction areas, shortened Li⁺ diffusion and potentially enhanced solubility/capacity. Integration with an electron-conductive second phase into the TiO₂-based nanostructures eases the electron transport, resulting in further improved lithium electrochemical activity and the overall electrochemical performance. This paper reviews structural characteristics and Li-electrochemical reactivity, along with synthetic approaches, of nanostructures and nano-composites based on lithium titanites and TiO₂ polymorphs that include rutile, anatase, bronze and brookite.     

Mechanisms linking socioeconomic status to smoking cessation: A structural equation modeling approach.

Objective: Although there has been a socioeconomic gradient in smoking prevalence, cessation, and disease burden for decades, these disparities have become even more pronounced over time. The aim of the current study was to develop and test a conceptual model of the mechanisms linking socioeconomic status (SES) to smoking cessation. Design: The conceptual model was evaluated using a latent variable modeling approach in a sample of 424 smokers seeking treatment (34% African American; 33% Latino; 33% White). Hypothesized mechanisms included social support, neighborhood disadvantage, negative affect/stress, agency, and craving. Main Outcome Measure: The primary outcome was Week 4 smoking status. Results: As was hypothesized, SES had significant direct and indirect effects on cessation. Specifically, neighborhood disadvantage, social support, negative affect/stress, and agency mediated the relation between SES and smoking cessation. A multiple group analysis indicated that the model was a good fit across racial/ethnic groups. Conclusion: The present study yielded one of the more comprehensive models illuminating the specific mechanisms that link SES and smoking cessation. Policy, community, and individual-level interventions that target low SES smokers and address the specific pathways identified in the current model could potentially attenuate the impact of SES on cessation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)