Investigation of Spillover Effect to Enhance Hydrogen Storage

Hydrogen is an attractive energy option because of its lowenvironmental impact, but a critical problem is its low energydensity, which makes it difficult to store. For example, the USDepartment of Energy (DOE) hydrogen plan for fuel cell poweredvehicles requires a gravimetric density of 6.5 wt%. There are severalexisting hydrogen storage methods, including compressed gas,liquefaction, metal hydrides, and physisorption, but at present, noneof these technologies comes close to achieving the targets set by theDOE. Although chemical storage methods have been claimed to be themost promising hydrogen storage technology, and activated carbons thebest adsorbent, as mentioned, chemical storage methods are still farfrom the desired targets. In order to try to bring these chemicalstorage methods closer to desired targets, research must be done tofind ways to maximize chemical storage potential using differentmaterials. Recently, there has been a resurgence of interest in thepotential of carbon materials. In order to try to move these hydrogenstorage goals further toward the goals of the DOE, numerousexperiments were done in altering the current materials to try tomaximize the hydrogen storage potential. Hydrogen Spillover, onemethod currently being considered, is where a metal catalystdissociates hydrogen molecules into atomic hydrogen, which thenmigrates down toward the carbon surface and is adsorbed onto thecarbon receptor. Experiments were done to compare the spillovereffects of multiple precious metals. Also, the use of basic highsurface area activated carbon (MSC-30) was compared to similaractivated carbons with Boron doping, with hopes of seeing anenhancement of that spillover effect. Unfortunately, no significantincreases on the current storage capacity via spillover of ~1.2wt%were achieved

Aspects of Bifurcation Theory for Piecewise-Smooth, Continuous Systems

Systems that are not smooth can undergo bifurcations that are forbidden in smooth systems. We review some of the phenomena that can occur for piecewise-smooth, continuous maps and flows when a fixed point or an equilibrium collides with a surface on which the system is not smooth. Much of our understanding of these cases relies on a reduction to piecewise linearity near the border-collision. We also review a number of codimension-two bifurcations in which nonlinearity is important.Comment: pdfLaTeX, 9 figure

Low-cost in-fiber WDM devices using tilted FBGs

We report the realization of low-cost in-fiber WDM device function utilizing efficient side-detection of strong radiation mode out-coupling from tilted FBGs. The spatial-to-spectral conversion efficiency as high as 0.32 mm/nm is demonstrated

Study of Optical-Feedback Using an Integrated Laser-Modulator/Amplifier Device

We study optical-feedback effects using an integrated laser-modulator/amplifier. Our experiment and theory are agree well and provide interesting results of feedback effects on optical spectrum, spatial-hole burning, the photon density profile, and the microwave modulation

Telomere length is a critical determinant for survival in multiple myeloma

The variable clinical outcomes of Multiple Myeloma (MM) patients are incompletely defined by current prognostication tools. We examined the clinical utility of high‐resolution telomere length analysis as a prognostic marker in MM. Cohort stratification, using a previously determined length threshold for telomere dysfunction, revealed that patients with short telomeres had a significantly shorter overall survival (P < 0·0001; HR = 3·4). Multivariate modelling using forward selection identified International Staging System (ISS) stage as the most important prognostic factor, followed by age and telomere length. Importantly, each ISS prognostic subset could be further risk‐stratified according to telomere length, supporting the inclusion of this parameter as a refinement of the ISS. Despite the introduction of novel therapeutic modalities, patients with multiple myeloma (MM) display a heterogeneous clinical course, with survival ranging from a few months to over 10 years. Therefore, there is a requirement for reliable prognostic and predictive markers in this disease to allow for risk stratification and rational clinical decision‐making. The most commonly used prognostic system in MM is the International Staging System (ISS) that is based on serum levels of both β2‐micoglobulin and albumin (Greipp et al, 2005). Recently the ISS has been improved upon by the inclusion of cytogenetic information to take into account the level of lactate dehydrogenase and the considerable genetic heterogeneity known to occur in this disease (Palumbo et al, 2015). Hyperdiploidy and the loss of whole chromosome arms is frequently detected in MM, which includes, amongst others, gains of 1q in 30% of cases and the loss of 17p in 7% of cases (Walker et al, 2010). Short dysfunctional telomeres are susceptible to DNA repair activities that can result in chromosomal fusion and the initiation of cycles of anaphase‐bridging, breakage and fusion that can drive genomic instability and clonal evolution (Artandi et al, 2000; Roger et al, 2013; Jones et al, 2014). Telomere dysfunction has been documented in numerous haematological malignancies (Jones et al, 2012), and is one putative mechanism that may lead to the genetic and clinical heterogeneity observed in MM (Wu et al, 2003) and may relate to changes in the 3D telomeric architecture that have been documented in MM cells (Klewes et al, 2013). Recently, we have shown that high‐resolution telomere analysis, combined with a functional definition of telomere length, can provide powerful prognostic information in several tumour types, including chronic lymphocytic leukaemia (CLL)(Lin et al, 2014), myelodysplasia (unpublished observations) and breast cancer (Simpson et al, 2015). Here we sought to apply these technologies to examine the prognostic utility of telomere length in MM

“Dicing and splicing” sphingosine kinase and relevance to cancer

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. Sphingosine kinase (SphK) is a lipid enzyme that maintains cellular lipid homeostasis. Two SphK isozymes, SphK1 and SphK2, are expressed from different chromosomes and several variant isoforms are expressed from each of the isozymes, allowing for the multi-faceted biological diversity of SphK activity. Historically, SphK1 is mainly associated with oncogenicity, however in reality, both SphK1 and SphK2 isozymes possess oncogenic properties and are recognized therapeutic targets. The absence of mutations of SphK in various cancer types has led to the theory that cancer cells develop a dependency on SphK signaling (hyper-SphK signaling) or “non-oncogenic addiction”. Here we discuss additional theories of SphK cellular mislocation and aberrant “dicing and splicing” as contributors to cancer cell biology and as key determinants of the success or failure of SphK/S1P (sphingosine 1 phosphate) based therapeutics

Impact of hydrogenation conditions on the temperature and strain coefficients of type 1 and typela dual grating sensors

We report experimental findings for tailoring the temperature and strain coefficients of Type 1 and Type 1A fibre Bragg gratings by influencing the photosensitivity presensitisation of the host optical fibre. It is shown that by controlling the level of hydrogen saturation, via hot and cold hydrogenation, it is possible to produce gratings with lower thermal coefficients. Furthermore, there is a larger difference between the Type 1 and Type 1A thermal coefficients and a significant improvement in the matrix condition number, which impacts the ability to recover accurate temperature and strain invariant data using the Type 1-1A dual grating sensor

Solution-Phase Synthesis of Heteroatom-Substituted Carbon Scaffolds for Hydrogen Storage

This paper reports a bottom-up solution-phase process for the preparation of pristine and heteroatom (boron, phosphorus, or nitrogen)-substituted carbon scaffolds that show good surface areas and enhanced hydrogen adsorption capacities and binding energies. The synthesis method involves heating chlorine-containing small organic molecules with metallic sodium at reflux in high-boiling solvents. For heteroatom incorporation, heteroatomic electrophiles are added to the reaction mixture. Under the reaction conditions, micrometer-sized graphitic sheets assembled by 3−5 nm-sized domains of graphene nanoflakes are formed, and when they are heteroatom-substituted, the heteroatoms are uniformly distributed. The substituted carbon scaffolds enriched with heteroatoms (boron ~7.3%, phosphorus ~8.1%, and nitrogen ~28.1%) had surface areas as high as 900 m^2 g^(−1) and enhanced reversible hydrogen physisorption capacities relative to pristine carbon scaffolds or common carbonaceous materials. In addition, the binding energies of the substituted carbon scaffolds, as measured by adsorption isotherms, were 8.6, 8.3, and 5.6 kJ mol^(−1) for the boron-, phosphorus-, and nitrogen-enriched carbon scaffolds, respectively