Search

The processes of hydrogen charging to and discharging from a 3-L cryogenic tank have been studied experimentally and numerically. This study investigated the impacts of factors such as mass flow rate, outlet opening time, bed density, and heating power on the hydrogen charging and discharging processes. For charging, it was found that the flow-through cooling technique could remove the adsorption heat in the process, but some issues such as channeling phenomenon and large thermal mass of the system need to be addressed. Low initial bed temperature is beneficial for hydrogen storage in terms of the efficiency of charging operation. When the bed density of metal organic framework-5 (MOF-5) is increased from 164 kg/m 3 to 174 kg/m 3 , the total storage of hydrogen within the tank increases accordingly. It is found that pressure is the major factor that determines the storage of hydrogen, which increases significantly with the pressure within the tank. For discharging, high pressure in the storage tank can be used to release hydrogen for a certain period of time without heating. However, in order to maintain the desired hydrogen discharge rate, a heat source is eventually needed. This heat must be supplied in order to desorb the additional hydrogen from the system. To deal with the channeling phenomenon in the charging process, cyclic charging was tested and adopted. [ABSTRACT FROM AUTHOR]

A characteristic feature of celiac disease is the presence of circulating autoantibodies targeted against transglutaminase 2 (TG2), reputed to have a function in angiogenesis. In this study we investigated whether TG2-specific autoantibodies derived from celiac patients inhibit angiogenesis in both ex vivo and in vivo models and sought to clarify the mechanism behind this phenomenon. We used the ex vivo murine aorta-ring and the in vivo mouse matrigel-plug assays to address aforementioned issues. We found angiogenesis to be impaired as a result of celiac disease antibody supplementation in both systems. Our results also showed the dynamics of endothelial cells was affected in the presence of celiac antibodies. In the in vivo angiogenesis assays, the vessels formed were able to transport blood despite impairment of functionality after treatment with celiac autoantibodies, as revealed by positron emission tomography. We conclude that celiac autoantibodies inhibit angiogenesis ex vivo and in vivo and impair vascular functionality. Our data suggest that the anti-angiogenic mechanism of the celiac disease-specific autoantibodies involves extracellular TG2 and inhibited endothelial cell mobility. [ABSTRACT FROM AUTHOR]

Abstract: Compaction of sodium alanate doped with 3 mol% titanium chloride (TiCl3) into rigid cylindrical pellets improves thermal conductivity, density and volumetric hydrogen capacity of a traditionally poorly conductive material. However, hydrogen cycling of alanate pellets results in significant expansion which counteracts the advantages of compaction. Restricting the area in which pellets can expand into minimizes these losses with no adverse effect to cycling capacity. Confined pellets had a 50% less decrease in density over 30 cycles, 5 times greater thermal conductivity within 10 cycles and maintain structural integrity through 50 cycles compared to free pellets. In addition, pellets within mechanical confinement fused into a rigid stack within the first few hydrogen cycles thereby reducing surface contact resistance between pellets by 3.5 times. Improved thermal conductivity and heat transfer through a pellet bed of materials such as complex metal hydrides, is a key aspect for on-board storage applications. [Copyright &y& Elsevier]

Abstract: Sodium alanate powder comprised of NaH and Al was doped with 3 mol% titanium chloride (TiCl3) and pelletized into highly compacted cylindrical pellets. The pelletization process was performed to improve thermal conductivity and volumetric hydrogen capacity of the metal hydride, compared to loose or tapped powder, which are vital requirements for on-board hydrogen storage applications. The pelletization process was performed over a range of 69–345 MPa (10–50 kPSI) with a 95% increase in density and improvement in thermal conductivity 18 times greater compared to powder at the maximum pelletization pressure (1.60 g/cm3 and 0.82 g/cm3; 9.09 W/m K and 0.50 W/m K, respectively). Hydrogen cycling capacities and kinetics were not adversely affected by the pelletization process although 10 cycles are required to obtain full hydrogen capacity. Pellet cycling capacity maintained a stable 4 wt% H2 over 50 cycles. Ti-doped NaH + Al pellets exhibited similar thermal cycling expansion as with the loose powder; within 30 cycles there was a 50% loss in pellet density and by 50 cycles the loss in pellet structural integrity made handling problematic. [Copyright &y& Elsevier]

In this paper, we propose a framework of hierarchical feature distribution for object matching in a network of visual sensors. In our approach, we hierarchically distribute the information in such a way that each individual node maintains only a small amount of information about the objects seen by the network. Nevertheless, this amount is sufficient to efficiently route queries through the network without any degradation of the matching performance. A set of requirements that have to be fulfilled by the object-matching method to be used in such a framework is defined. We provide examples of mapping four well-known, object-matching methods to a hierarchical feature-distribution scheme. The proposed approach was tested on a standard COIL-100 image database and in a basic surveillance scenario using our own distributed network simulator. The results show that the amount of data transmitted through the network can be significantly reduced in comparison to naive feature-distribution schemes such as flooding. [ABSTRACT FROM AUTHOR]

Today's automobiles are fitted with antennas for many wireless services, with modern vehicular antennas frequently configured in blade or “shark-fin” housings, or as planar roof mounted antennas. In these configurations vehicle manufacturers may wish to improve the appearance of the finished vehicle by painting these antennas or their coverings. This paper provides experimental results detailing the effect of two commonly used automotive paint chemistries both with and without the metallic particles used to create a “metallic paint” effect. Electrostatic primers are also considered. Narrowband and wideband antennas are investigated, and the effect of these coatings on impedance bandwidth and radiation is observed. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to extend the deformation model of a communication device embedded in a viscoelastic thermoset composite polymer such as Sheet Moulding Compound (SMC). The original model takes into account time dependent heat transfer from the mould surface into the SMC charge and the consequent time dependent viscosity propagation during the initial stage of mould closing and subsequent filling. The required model parameters for viscosity and elasticity have been determined from rheological testing. The extended model will examine the effects of a number of process parameters such as mould closing speed, mould temperature and initial charge temperature. The effect of these parameters on the deformation of the communication device is discussed and compared to experimental findings. In addition the signal quality due to antenna deformation as a result of its embedding process is investigated by comparing simulation and experimental results. [ABSTRACT FROM AUTHOR]

NaAlH4 with TiCl3 and Al were mixed by ball-milling and cycled three times. The hydrogen storage properties were monitored during cycling, and the products were characterized by synchrotron X-ray diffraction. Because of the previously described formation of Al1-yTiy with y ≈ 0.15 during cycling that traps Al beyond the amount associated with the formation of NaCl, some Na3AlH6 has no free Al to react with to form NaAlH4. This was counteracted in the present work by adding a stoichiometric amount of Al that increases the theoretical storage capacity. Due to limitations in metal diffusion small amounts of Na3AlH6 were still detected. When ∼7 mol % more Al than the stoichiometric amount was added, the observed storage capacity increased significantly, and the Na3AlH6 content was negligible after prolonged rehydrogenation. Cycled NaAlH4 + 10 mol % TiCl3 were desorbed to two different levels, and the diffraction patterns were compared. There is no change in unit-cell dimensions during desorption, and there is no sign of changes in the bulk composition of the Al1-yTiy phase during a cycle. Adding pure Ti to a NaH + Al mixture by ball-milling in argon or hydrogen results in formation of TiH2 that is stable during at least one cycle. [ABSTRACT FROM AUTHOR]

This work combines materials development with hydrogen storage technology advancements to address onboard hydrogen storage challenges in light-duty vehicle applications. These systems are comprised of the vehicle requirements design space, balance of plant requirements, storage system components, and materials engineering culminating in the development of an Adsorbent System Design Tool that serves as a preprocessor to the storage system and vehicle-level models created within the Hydrogen Storage Engineering Center of Excellence. Computational and experimental efforts were integrated to evaluate, design, analyze, and scale potential hydrogen storage systems and their supporting components against the Department of Energy 2020 and Ultimate Technical Targets for Hydrogen Storage Systems for Light Duty Vehicles. Ultimately, the Adsorbent System Design Tool was created to assist material developers in assessing initial design parameters that would be required to estimate the performance of the hydrogen storage system once integrated with the full fuel cell system. [Display omitted] • Model analysis of adsorption-based hydrogen system for fuel cell applications. • Evaluation of various engineering design options for tank and balance-of-plant. • Thermodynamic equations to predict charging/discharging of activated carbon and MOF-5. • Prototype validation and model sensitivity analysis for data comparison. • Full-vehicle level analysis compared to DOE standards to determine applicability. [ABSTRACT FROM AUTHOR]

Abstract High pressure metal hydrides are materials that can be used both to store and to compress hydrogen effectively. In order to meet the U. S. Department of Energy techno-economic targets for storage and compression of hydrogen, new material formulations need to be identified and characterized. A novel high-throughput integrated methodology has been developed, allowing for high pressure metal hydride material characterization with reduced time and efforts. The methodology integrates an optical system that can detect the deflection of thin layer material cantilevers during uptake and release of hydrogen. A Matlab® code has also been developed and integrated, allowing for the identification of pressure-temperature profiles in regard to the cantilever deflection during absorption and desorption. The methodology has been successfully validated for low pressure (Pd hydride) and high pressure (TiCr 1.9 hydride) materials, comparing the predicted thermodynamic properties for thin layer materials with the bulk material data available in the literature. The difference between the predicted reaction enthalpy and entropy and the literature data for the low-pressure material is below 10%. The high-pressure material predicted enthalpy and entropy values are also in excellent agreement with the literature data with differences less than 4%. Highlights • A novel high-throughput integrated methodology developed. • Thermodynamic properties of low pressure thin layer metal hydride material (Pd hydride) assessed. • Thermodynamic properties of high pressure thin layer metal hydride material (TiCr 2 hydride) assessed. • Comparison with literature data carried out, showing excellent agreement. [ABSTRACT FROM AUTHOR]

Concentrating solar power plants represent low cost and efficient solutions for renewable electricity production only if adequate thermal energy storage systems are included. Metal hydride thermal energy storage systems have demonstrated the potential to achieve very high volumetric energy densities, high exergetic efficiencies, and low costs. The current work analyzes the technical feasibility and the performance of a storage system based on the high temperature Mg 2 FeH 6 hydride coupled with the low temperature Na 3 AlH 6 hydride. To accomplish this, a detailed transport model has been set up and the coupled metal hydride system has been simulated based on a laboratory scale experimental configuration. Proper kinetics expressions have been developed and included in the model to replicate the absorption and desorption process in the high temperature and low temperature hydride materials. The system showed adequate hydrogen transfer between the two metal hydrides, with almost complete charging and discharging, during both thermal energy storage and thermal energy release. The system operating temperatures varied from 450 °C to 500 °C, with hydrogen pressures between 30 bar and 70 bar. This makes the thermal energy storage system a suitable candidate for pairing with a solar driven steam power plant. The model results, obtained for the selected experimental configuration, showed an actual thermal energy storage system volumetric energy density of about 132 kWh/m 3 , which is more than 5 times the U.S. Department of Energy SunShot target (25 kWh/m 3 ). [ABSTRACT FROM AUTHOR]

Abstract: Titanium-catalyzed sodium–aluminum hydride has been studied by using in situ TEM heating experiments in conjunction with electron energy loss spectroscopy and X-ray energy dispersive spectroscopy. Electron energy loss spectroscopy (EELS) standards of Ti, TiO2, Ti3Al, cubic Al3Ti, orthorhombic Al3Ti, TiH2, and TiCl3 were prepared and analyzed to enable identification of the form of Ti and how it changes as a function of the number of hydrogenation–dehydrogenation cycles. The TiCl3 precursor in NaAlH4 when cycled at 3wt.% H2 capacity remains after 5 cycles but is eliminated by the 10th cycle. The dominant form of Ti is then cubic Al3Ti. The number of cycles required to achieve this depends on the cycled capacity, with partially cycled requiring more cycles than fully cycled material. The form and location of the Ti responsible for the enhanced performance was not discovered which has implications for the effective amount of Ti. The effects of the electron beam and exposure to air on the particles are shown and discussed. [Copyright &y& Elsevier]

Coeliac disease is hallmarked by an abnormal immune reaction against ingested wheat-, rye- and barley-derived gluten and the presence of transglutaminase 2 (TG2)-targeted autoantibodies. The small-bowel mucosal damage characteristic of the disorder develops gradually from normal villus morphology to inflammation and finally to villus atrophy with crypt hyperplasia. Patients with early-stage coeliac disease have TG2-autoantibodies present in serum and small-intestinal mucosa and they may already suffer from abdominal symptoms before the development of villus atrophy. Previously, we have shown that intraperitoneal injections of coeliac patient-derived sera or purified immunoglobulin fraction into mice induce a condition mimicking early-stage coeliac disease. In the current study, we sought to establish whether recombinantly produced patient-derived TG2-targeted autoantibodies are by themselves sufficient for the development of such an experimentally induced condition in immune-compromised mice. Interestingly, mice injected with coeliac patient TG2-antibodies had altered small-intestinal mucosal morphology, increased lamina propria cellular infiltration and disease-specific autoantibodies deposited in the small bowel, but did not evince clinical features of the disease. Thus, coeliac patient-derived TG2-specific autoantibodies seem to be sufficient for the induction of subtle small-bowel mucosal alterations in mice, but the development of clinical features probably requires additional factors such as other antibody populations relevant in coeliac disease. [ABSTRACT FROM AUTHOR]

Celiac patient-derived anti-transglutaminase 2 (TG2) antibodies disturb several steps in angiogenesis, but the detailed molecular basis is not known. Therefore, we here analyzed by microarray technology the expression of a set of genes related to angiogenesis and endothelial cell biology in order to identify factors that could explain our previous data related to vascular biology in the context of celiac disease. To this end, in vitro models using human umbilical vein endothelial cells (HUVECs) or in vivo models of angiogenesis were used. A total of 116 genes were analyzed after treatment with celiac patient autoantibodies against TG2. Compared to treatment with control IgA celiac patient, total IgA induced a consistent expression change of 10 genes, the up-regulation of four and down-regulation of six. Of these genes the up-regulated RhoB was selected for further studies. RhoB expression was found to be up-regulated at both messenger RNA and protein level in response to celiac patient total IgA as well as anti-TG2-specific antibody derived from a celiac patient. Interestingly, down-regulation of RhoB by specific small interfering RNA treatment in endothelial cells could rescue the deranged endothelial length and tubule formation caused by celiac disease autoantibodies. RhoB function is controlled by its post-translational modification by farnesylation. This modification of RhoB required for its correct function can be prevented by the cholesterol lowering drug simvastatin, which was also able to abolish the anti-angiogenic effects of celiac anti-TG2 autoantibodies. Taken together, our results would suggest that RhoB plays a key role in the response of endothelial cells to celiac disease-specific anti-TG2 autoantibodies. [ABSTRACT FROM AUTHOR]

Abstract: The NaAlH4 + xTiCl3 (x <0.1) system has been studied by a combination of X-ray synchrotron and neutron diffraction, and isotopic H2/D2 scrambling after the completion of the milling process, and the first thermal release of hydrogen (H). An in situ X-ray synchrotron diffraction study of the isochronal release of hydrogen from planetary milled (PM) NaAlH4 +0.1TiCl3 shows that crystalline (c-) Al1−x Ti x phases do not form until almost all H is released from the sample, demonstrating that the surface embedded nanoscopic crystalline Al/amorphous (a-) Al50Ti50 composite facilitates the release of H during the very first thermal desorption. Planetary milled (PM) NaAlH4 + xTiCl3 is observed to disproportionate at room temperature, with no NaAlH4 remaining after ca. 200 days. A complete lack of ambient hydrogen release from PM NaAlH4 +0.1Al (80nm) measured over 200 days suggests that the nanoscopic a-Al50Ti50 phase is entirely responsible for the hydrogen release during thermal desorption of milled NaAlH4 + xTiCl3. Isotopic H/D exchange has been observed by combined neutron and X-ray synchrotron diffraction on a PM NaAlD4 +0.04TiCl3 sample, after exposing the milled sample to 20bar H2 at 50°C for ca. 6 days. Under these pressure/temperature (P/T) conditions, disproportionation of NaAlD4 is avoided, and ca. 32% of D atoms are exchanged with H atoms. Asymmetrically broadened reflections in the synchrotron data show peak splitting into two unit cell types, one expanded with H, the other remaining close to pure D based unit cell dimensions. The 2-phase model when fitted to the neutron data demonstrates that ca. 56% of D atoms in ca. 58% of all unit cells are exchanged with H, yielding a NaAl(H0.56D0.44)4 composition for the expanded unit cells. HD scrambling (1bar mixture of H2 and D2 at 23°C) performed on desorbed H empty PM NaAlH4 +0.1TiCl3 shows classic H2 +D2 ↔2HD equilibrium mixing, demonstrating that nanoscopic Ti containing Al1−x Ti x surface embedded phases perform a H2 dissociation/recombination function that unadulterated NaAlH4 cannot. [Copyright &y& Elsevier]

Abstract: The NaAlH4 + xTiCl3 (x <0.1) system has been studied by X-ray synchrotron diffraction and transmission electron microscopy (TEM) after the completion of the milling process, for both planetary (PM) and cryo milled (CM) samples. Comparison of the NaAlH4 mosaic size (coherence length) determined from the X-ray synchrotron diffraction lineshape, and measurement of the external powder grain dimensions of ca. 250–300 particles by TEM, reveals that after the completion of the milling process, 〈110〉 {111} edge dislocated 2–20nm Al crystallites are dispersed in a Ti rich amorphous (a-)Al1−x Ti x (0.3< x <0.5) matrix. This nano Al/Al50Ti50 composite is embedded on the surface of single crystalline NaAlH4 powder grains. The NaAlH4 single crystal powder grains are moderately defected with uncorrelated defects, induced from the milling process. [Copyright &y& Elsevier]

Background and objective Antitransglutaminase (anti-TG2) antibodies are synthesised in the ntestine and their presence seems predictive of future coeliac disease (CD). This study investigates whether mucosal antibodies represent an early stage of gluten intolerance even in the absence of intestinal damage and serum anti-TG2 antibodies. Methods This study investigated 22 relatives of patients with CD genetically predisposed to gluten intolerance but negative for both serum anti-TG2 antibodies and intestinal abnormalities. Fifteen subjects were symptomatic and seven were asymptomatic. The presence of immunoglobulin A anti-TG2 antibodies in the intestine was studied by creating phage-antibody libraries against TG-2. The presence of intestinal anti-TG2 antibodies was compared with the serum concentration of the intestinal fatty acid-binding protein (I-FABP), a marker for early intestinal mucosal damage. The effects of a 12-month gluten-free diet on anti-TG2 antibody production and the subjects' clinical condition was monitored. Twelve subjects entered the study as controls. Results The intestinal mucosa appeared normal in 18/22; 4 had a slight increase in intraepithelial lymphocytes. Mucosal anti-TG2 antibodies were isolated in 15/22 subjects (68%); in particular symptomatic subjects were positive in 13/15 cases and asymptomatic subjects in 2/7 cases (&Rgr;=0.01). No mucosal antibodies were selected from the controls' biopsies. There was significant correlation between the presence of intestinal anti-TG2 antibodies and positive concentrations of I-FABP (&Rgr;=0.0008). After a gluten-free diet, 19/22 subjects underwent a second intestinal biopsy, which showed that anti-TG2 antibodies had disappeared in 12/15 (&Rgr;=0.002), while I-FABP decreased significantly (&Rgr;<0.0001). The diet resolved both extraintestinal and intestinal symptoms. Conclusions A new form of genetic-dependent gluten intolerance has been described in which none of the usual diagnostic markers is present. Symptoms and intestinal anti-TG2 antibodies respond to a gluten free-diet. The detection of intestinal anti-TG2 antibodies by the phage-antibody libraries has an important diagnostic and therapeutic impact for the subjects with gluten-dependent intestinal or xtraintestinal symptoms. INSET: Significance of this study. [ABSTRACT FROM AUTHOR]

Objective. Earlier work has demonstrated that serum autoantibodies from coeliac patients targeted against transglutaminase 2 (TG2) inhibit in vitro angiogenesis. The aim of this study was to establish whether coeliac patient-derived monoclonal TG2-targeted antibodies produced by recombination technology exert similar anti-angiogenic effects to serum-derived coeliac autoantibodies. In addition, we studied whether the monoclonal patient autoantibodies modulate endothelial cell TG2 activity and whether such modulation is related to the anti-angiogenic effects. Material and methods. The influence of coeliac patient-derived monoclonal TG2-targeted antibodies on endothelial cell tubule formation was studied using a three-dimensional angiogenic cell culture model. Endothelial cell TG2 enzymatic activity was determined by means of a live-cell enzyme-linked immunosorbent assay. Results. Coeliac patient-derived monoclonal TG2-targeted antibodies produced by recombination technology inhibited endothelial tubule formation and enhanced the crosslinking activity of TG2. When this enzymatic activity was inhibited using site-directed irreversible TG2 inhibitors in the presence of autoantibodies, in vitro angiogenesis reverted to the control level. Conclusions. Since we found a significant negative correlation between endothelial cell angiogenesis and TG2 activity, we suggest that the anti-angiogenic effects of coeliac patient-derived TG2-targeted autoantibodies are exerted by enhanced enzymatic activity of TG2. [ABSTRACT FROM AUTHOR]

Abstract: The twice-hydrogen-cycled NaAlH4 + xTiCl3 (x <0.15) system has been studied by high-resolution X-ray synchrotron diffraction and transmission electron microscopy. Intense low d-spacing shoulders are formed on Al reflections, indicating the formation of a face-centred cubic Al85Ti15 solid solution of unit cell dimension 4.0356Å. The Al85Ti15 solid solution is found as isolated 4–25nm nanocrystallites on the NaAlH4 surface. The Al85Ti15 phase is highly 〈110〉{111} edge dislocated to ∼6×1016 m−2. Local energy-dispersive spectroscopy shows an Al:Ti ratio consistent with an Al85Ti15 composition, confirming an extended solubility of Ti in Al. Structural analysis indicates a quenched L12 superlattice obtained by Al and Ti sublattice swapping, yielding an equivalent A1 model to describe the Al85Ti15 crystal structure. [Copyright &y& Elsevier]

A systematic study of the dehydrogenation process of undoped and of catalyzed NaAlH4by means of anelastic spectroscopy is presented. Evidence is reported of the formation of a highly mobile species during decomposition, which has been identified in off-stoichiometric AlH6-xunits, giving rise to fast H vacancy local dynamics. The formation of such stoichiometry defects starts at temperatures much lower in Ti doped than in undoped samples, and concomitantly with the decomposition reaction. The catalyst atoms decrease the energy barrier to be overcome by H to break the bond, thus enhancing the kinetics of the chemical reactions and decreasing the temperature at which the dehydrogenation processes take place. The experimental data show that not all the hydrogen released by the formula units during the evolution of decomposition evolves out of the sample, but part of it remains in the lattice and migrates on a long-range scale within the sample. We identify, in this H mobilized population, the species which induces the fast tetragonal to monoclinic phase transformation accompanying decomposition. A partial spontaneous thermally activated regression of decomposition has also been observed by aging experiments. A model is proposed which accounts for the action of the Ti catalyst and for the atomistic mechanism of decomposition. [ABSTRACT FROM AUTHOR]

Abstract: The effects of milling and doping NaAlH4 with TiCl3, TiF3 and Ti(OBun)4, and of cycling doped NaAlH4 have been investigated by infrared (IR) and Raman spectroscopy and X-ray powder diffraction. Milling and doping produce similar effects. Both decrease the crystal domain size (∼900Å for milled and ∼700Å for doped, as compared to ∼1600Å for unmilled and undoped NaAlH4) and increase anisotropic strain (by a factor >2.5, mainly along c). They also influence structure parameters such as the axial ratio c/a, cell volume and atomic displacement amplitudes. They show IR line shifts by ∼15cm-1 to higher frequencies for the Al–H asymmetric stretching mode ν3, and by ∼20cm-1 to lower frequencies for one part of the H–Al–H asymmetric bending mode ν4, thus suggesting structural changes in the local environment of the [AlH4]- units. The broad ν3 bands become sharpened which suggests a more homogeneous local environment of the [AlH4]- units, and there appears a new vibration at 710cm-1. The Raman data show no such effects. Cycling leads to an increase in domain size (1200–1600Å), IR line shifts similar to doped samples (except for TiF3: downward shift by ∼10cm-1) and a general broadening of the ν3 mode that depend on the nature of the dopants. These observations support the idea that some Ti diffusion and substitution into the alanate lattice does occur, in particular during cycling, and that this provides the mechanism through which Ti-doping enhances kinetics during re-crystallisation. [Copyright &y& Elsevier]

A correction to the article "RhoB is associated with the anti-angiogenic effects of celiac patient transglutaminase 2-targeted autoantibodies" that was published in the 2011 issue is presented.