Application of Glow Discharge Plasma to Alter Surface Properties of Materials

Some polymer materials that are considered important for spaceport operations are rendered noncompliant when subjected to the Kennedy Space Center (KSC) Standard electrostatic testing. These materials operate in stringent environmental conditions, such as high humidity. Treating materials that fail electrostatic testing and altering their surface properties so that they become compliant would result in considerable cost savings. Significant improvement in electrostatic dissipation of Saf-T-Vu PVC after treatment with air Atmospheric Plasma Glow Discharge (APGD) was observed and the material now passed the KSC electrostatic test. The O:C ratio on the surface, as monitored by X-ray Photoelectron Spectroscopy, increased from 0.165 tO 0.275 indicating enhanced oxidation, and surface contact angle measurements decreased from 107.5 to 72.6 showing increased hydrophilicity that accounted for the increased conductivity. Monitoring of the aging showed that the materials hydrophobic recovery resulted in it failing the electrostatic test 30 hours after treatment. This was probably due to the out-diffusion of the added Zn, Ba, and Cd salt stabilizers detected on the surface and/or diffusion of low molecular weight oligomers. On going work includes improving the long term hydrophilicity by optimizing the APGD process with different gas mixtures. Treatment of other spaceport materials is also presented

ESD Challenges for NASA Astronauts in Upcoming Missions

Electrostatic charging of insulators is well known to pose potential threats to electronic systems under terrestrial systems. We were asked to evaluate potential hazards associated with replacement of an electronics board in the vacuum of space during the upcoming Hubble Service Repair mission in September 2008. A device called a "tribot" was built to simulate triboelectric charging of several insulators that are capable of contact charging against astronaut's gloves and suit materials. Materials were evaluated as the extent of not only the magnitude of electric fields generated by the frictional action, but also any resulting discharge which would be a source of EMI. Experimental results are quite surprising and unexpected when compared with tests performed under ambient conditions under dry and humid air

Paper Session II-A - Results of a Wheel Electrometer for Measuring the Triboelectric Properties of Martian Regolith

The preliminary results of a prototype Wheel Electrometer System (WES) are presented that show that it is indeed possible to use the static electricity generated between polymers and soils after contact (triboelectricity) as a means of detecting property changes. Changes in the triboelectric signals offer information as to the mechanical properties of the soil such as grain size differences, texture, hardness and even moisture content. Initially, four polymers are chosen that span the triboelectric series such as Teflon, Lucite, Fiberglass and Lexan. It is shown that the average charge on Teflon is much higher when rolled over beach sand as compared to Martian simulant and limestone. Lucite was the most susceptible to particle size differences, while Lexan was able to detect underlying materials in the case of a soil lightly covered with a different soil type. All polymers responded differently when rolled over dry soil compared with moist soil. This information can be used as a type of triboelectric spectroscopy when a library of data is used to categorize the unique charging characteristics of individual polymers. This system is of great interest to planetary scientists and such measurements may be included in future Mars rover missions

Effect of Non-Magnetic Impurities (Zn,Li) in a Hole Doped Spin-Fermion Model for Cuprates

The effect of adding non-magnetic impurities (NMI), such as Zn or Li, to high-Tc cuprates is studied applying Monte Carlo techniques to a spin-fermion model. It is observed that adding Li is qualitatively similar to doping with equal percentages of Sr and Zn. The mobile holes (MH) are trapped by the NMI and the system remains insulating and commensurate with antiferromagnetic (AF) correlations. This behavior persists in the region %NMI > %MH. On the other hand, when %NMI < %MH magnetic and charge incommensurabilities are observed. The vertical or horizontal hole-rich stripes, present when % NMI=0 upon hole doping, are pinned by the NMI and tend to become diagonal, surrounding finite AF domains. The %MH-%NMI plane is investigated. Good agreement with experimental results is found in the small portion of this diagram where experimental data are available. Predictions about the expected behavior in the remaining regions are made.Comment: Four pages with four figures embedded in tex

Magnetic Domains and Stripes in the Spin-Fermion Model for Cuprates

Monte Carlo simulations applied to the Spin-Fermion model for cuprates show the existence of antiferromagnetic spin domains and charge stripes upon doping. The stripes are partially filled, with a filling of approximately 1/2 hole per site, and they separate spin domains with a $\pi$ phase shift among them. The stripes observed run either along the x or y axes and they are separated by a large energy barrier. No special boundary conditions or external fields are needed to stabilize these structures at low temperatures. When magnetic incommensurate peaks are observed at momentum $\pi(1,1-\delta)$ and symmetrical points, charge incommensurate peaks appear at $(0,2 \delta)$ and symmetrical points, as experimentally observed. The strong charge fluctuations responsible for the formation of the stripes also induce a pseudogap in the density of states.Comment: Four pages with four figures embedded in tex

The CERN Neutrino beam to Gran Sasso (NGS)

The conceptual technical design of the NGS (CERN neutrino beam to Gran Sasso) facility has been presented in the report CERN 98-02 / INFN-AE/98-05. Additional information, in particular an update on various neutrino beam options for the NGS facility, has been provided in a memorandum to the CERN-SPSC Committee (CERN-SPSC/98-35). In the present report, further improvements on the NGS design and performance, in particular new scenarios for SPS proton cycles for NGS operation and a new version of the NGS "high energy" neutrino beam for nt appearance experiments, are described. This new NGS reference beam is estimated to provide three times more nt events per year than the beam presented in the 1998 report. The radiological aspects of the NGS facility have been re-examined with the new beam design. An updated version of the construction schedule is also presented

Identification of Piwil2-Like (PL2L) Proteins that Promote Tumorigenesis

PIWIL2, a member of PIWI/AGO gene family, is expressed in the germline stem cells (GSCs) of testis for gametogenesis but not in adult somatic and stem cells. It has been implicated to play an important role in tumor development. We have previously reported that precancerous stem cells (pCSCs) constitutively express Piwil2 transcripts to promote their proliferation. Here we show that these transcripts de facto represent Piwil2-like (PL2L) proteins. We have identified several PL2L proteins including PL2L80, PL2L60, PL2L50 and PL2L40, using combined methods of Gene-Exon-Mapping Reverse Transcription Polymerase Chain Reaction (GEM RT-PCR), bioinformatics and a group of novel monoclonal antibodies. Among them, PL2L60 rather than Piwil2 and other PL2L proteins is predominantly expressed in various types of human and mouse tumor cells. It promotes tumor cell survival and proliferation in vitro through up-regulation of Stat3 and Bcl2 gene expressions, the cell cycle entry from G0/1 into S-phase, and the nuclear expression of NF-κB, which contribute to the tumorigenicity of tumor cells in vivo. Consistently, PL2L proteins rather than Piwil2 are predominantly expressed in the cytoplasm or cytoplasm and nucleus of euchromatin-enriched tumor cells in human primary and metastatic cancers, such as breast and cervical cancers. Moreover, nuclear PL2L proteins are always co-expressed with nuclear NF-κB. These results reveal that PL2L60 can coordinate with NF-κB to promote tumorigenesis and might mediate a common pathway for tumor development without tissue restriction. The identification of PL2L proteins provides a novel insight into the mechanisms of cancer development as well as a novel bridge linking cancer diagnostics and anticancer drug development

From staff-mix to skill-mix and beyond: towards a systemic approach to health workforce management

Throughout the world, countries are experiencing shortages of health care workers. Policy-makers and system managers have developed a range of methods and initiatives to optimise the available workforce and achieve the right number and mix of personnel needed to provide high-quality care. Our literature review found that such initiatives often focus more on staff types than on staff members' skills and the effective use of those skills. Our review describes evidence about the benefits and pitfalls of current approaches to human resources optimisation in health care. We conclude that in order to use human resources most effectively, health care organisations must consider a more systemic approach - one that accounts for factors beyond narrowly defined human resources management practices and includes organisational and institutional conditions