Catalytic Fluorination of Dichloromethane with Hydrofluoric Acid

The catalytic, vapor-phase fluorination of dichloromethane to chlorofluoromethane with 38% hydrofluoric acid was investigated as a model system for possible direct utilization of hydrofluoric acid in the production of fluorocarbons and chlorofluorocarbons. Catalysts consisting of Cr or Ni supported on alumina and Ni, Cr, Ag, Co, La, Sn, Hg(I), Hg(II), Cu, Fe, Ru, Zn, Na, or Ca supported on activated charcoal were utilized at various reaction temperatures and reactor residence times. Alumina-supported catalysts were found to have low activities for fluorination in comparison to catalysts utilizing anhydrous HF reported in the patent literature. The low activities were attributed to low catalyst surface areas resulting from the fluorination of the catalyst with aqueous HF. Carbon-supported catalysts were found, in general, to promote thermal cracking of the CH2Cl2 feed as well as the fluorination reaction. This thermal cracking was usually sufficiently severe to result in drastically lowered yields of the desired product and low catalyst lifetime due to coking. The greatest selectivities for the desired product, CH2ClF, relative to the difluorinated product, CH2F2, at reasonably high conversions, were obtained with Sn, Cu, or Co fluorides on an activated charcoal support, although overall yields were relatively low due to thermal cracking

DNA methyltransferase 3b regulates articular cartilage homeostasis by altering metabolism

Osteoarthritis (OA) is the most common form of arthritis worldwide. It is a complex disease affecting the whole joint but is generally characterized by progressive degradation of articular cartilage. Recent genome-wide association screens have implicated distinct DNA methylation signatures in OA patients. We show that the de novo DNA methyltransferase (Dnmt) 3b, but not Dnmt3a, is present in healthy murine and human articular chondrocytes and its expression decreases in OA mouse models and in chondrocytes from human OA patients. Targeted deletion of Dnmt3b in murine articular chondrocytes results in an early-onset and progressive postnatal OA-like pathology. RNA-Seq and methylC-Seq analyses of Dnmt3b loss-of-function chondrocytes show that cellular metabolic processes are affected. Specifically, TCA metabolites and mitochondrial respiration are elevated. Importantly, a chondroprotective effect was found following Dnmt3b gain of function in murine articular chondrocytes in vitro and in vivo. This study shows that Dnmt3b plays a significant role in regulating postnatal articular cartilage homeostasis. Cellular pathways regulated by Dnmt3b in chondrocytes may provide novel targets for therapeutic approaches to treat OA

On-Orbit Measurement of Next Generation Space Solar Cell Technology on the International Space Station

Measurement is essential for the evaluation of new photovoltaic (PV) technology for space solar cells. NASA Glenn Research Center (GRC) is in the process of measuring several solar cells in a supplemental experiment on NASA Goddard Space Flight Center's (GSFC) Robotic Refueling Mission's (RRM) Task Board 4 (TB4). Four industry and government partners have provided advanced PV devices for measurement and orbital environment testing. The experiment will be on-orbit for approximately 18 months. It is completely self-contained and will provide its own power and internal data storage. Several new cell technologies including four- junction (4J) Inverted Metamorphic Multijunction (IMM) cells will be evaluated and the results compared to ground-based measurements

Statin therapy, fitness, and mortality risk in middle-aged hypertensive male veterans

BACKGROUND Hypertension often coexists with dyslipidemia, accentuating cardiovascular risk. Statins are often prescribed in hypertensive individuals to lower cardiovascular risk. Higher fitness is associated with lower mortality, but exercise capacity may be attenuated in hypertension. The combined effects of fitness and statin therapy in hypertensive individuals have not been assessed. Thus, we assessed the combined health benefits of fitness and statin therapy in hypertensive male subjects. METHODS Peak exercise capacity was assessed in 10,202 hypertensive male subjects (mean age = 60.4±10.6 years) in 2 Veterans Affairs Medical Centers. We established 4 fitness categories based on peak metabolic equivalents (METs) achieved and 8 categories based on fitness status and statin therapy. RESULTS During the follow-up period (median = 10.2 years), there were 2,991 deaths. Mortality risk was 34% lower (hazard ratio (HR) = 0.66; 95% confidence interval (CI) = 0.59–0.74; P \u3c 0.001) among individuals treated with statins compared with those not on statins. The fitness-related mortality risk association was inverse and graded regardless of statin therapy status. Risk reduction associated with exercise capacity of 5.1–8.4 METs was similar to that observed with statin therapy. However, those achieving ≥8.5 METs had 52% lower risk (HR = 0.48; 95% CI = 0.37–0.63) when compared with the least-fit subjects (≤5 METs) on statin therapy. CONCLUSIONS The combination of statin therapy and higher fitness lowered mortality risk in hypertensive individuals more effectively than either alone. The risk reduction associated with moderate increases in fitness was similar to that achieved by statin therapy. Higher fitness was associated with 52% lower mortality risk when compared with the least fit subjects on statin therapy

Fluid dynamics of R-charged black holes

We construct electrically charged AdS_5 black hole solutions whose charge, mass and boost-parameters vary slowly with the space-time coordinates. From the perspective of the dual theory, these are equivalent to hydrodynamic configurations with varying chemical potential, temperature and velocity fields. We compute the boundary theory transport coefficients associated with a derivative expansion of the energy momentum tensor and R-charge current up to second order. In particular, we find a first order transport coefficient associated with the axial component of the current.Comment: 31 pages, v2: published version; added some references, discussion of the charge-current changed, results unchanged, v3: typo in formula (15) changed, v4: added footnote 3 in order to clarify the relation of our results to those of arXiv:0809.259

AMI observations of unmatched Planck ERCSC LFI sources at 15.75 GHz

The Planck Early Release Compact Source Catalogue includes 26 sources with no obvious matches in other radio catalogues (of primarily extragalactic sources). Here we present observations made with the Arcminute Microkelvin Imager Small Array (AMI SA) at 15.75 GHz of the eight of the unmatched sources at declination > +10 degrees. Of the eight, four are detected and are associated with known objects. The other four are not detected with the AMI SA, and are thought to be spurious.Comment: 6 pages, 5 figures, 4 table

Giant Gravitons - with Strings Attached (III)

We develop techniques to compute the one-loop anomalous dimensions of operators in the ${\cal N}=4$ super Yang-Mills theory that are dual to open strings ending on boundstates of sphere giant gravitons. Our results, which are applicable to excitations involving an arbitrary number of open strings, generalize the single string results of hep-th/0701067. The open strings we consider carry angular momentum on an S$^3$ embedded in the S$^5$ of the AdS$_5\times$S$^5$ background. The problem of computing the one loop anomalous dimensions is replaced with the problem of diagonalizing an interacting Cuntz oscillator Hamiltonian. Our Cuntz oscillator dynamics illustrates how the Chan-Paton factors for open strings propagating on multiple branes can arise dynamically.Comment: 66 pages; v2: improved presentatio

Some Calculable Contributions to Holographic Entanglement Entropy

Using the AdS/CFT correspondence, we examine entanglement entropy for a boundary theory deformed by a relevant operator and establish two results. The first is that if there is a contribution which is logarithmic in the UV cut-off, then the coefficient of this term is independent of the state of the boundary theory. In fact, the same is true of all of the coefficients of contributions which diverge as some power of the UV cut-off. Secondly, we show that the relevant deformation introduces new logarithmic contributions to the entanglement entropy. The form of some of these new contributions is similar to that found recently in an investigation of entanglement entropy in a free massive scalar field theory [1].Comment: 52 pages, no figure