Functionalized Activated Carbon Catalysts in Xylose Dehydration

Acid functionalized activated carbon was studied as a catalyst in xylose dehydration. It was compared with commonly used solid acid catalysts, H-mordenite and TiO₂. The carbon surface was modified with H₂SO₄ and/or HNO₃ treatment, resulting in highly active and selective dehydration catalysts that were stable in aqueous reaction conditions.     

Lipoprotein lipase induces catabolism of normal triglyceride-rich lipoproteins via the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor in vitro. A process facilitated by cell-surface proteoglycans

Bovine milk lipoprotein lipase (LPL) induced binding, uptake, and degradation of 125I-labeled normal human triglyceride-rich lipoproteins by cultured mutant fibroblasts lacking LDL receptors. The induction was dose-dependent and occurred whether LPL and 125I-lipoproteins were added to incubation media simultaneously or LPL was allowed to bind to cell surfaces, and unbound LPL was removed by washing prior to the assay. Lipolytic modification of lipoproteins did not appear to be necessary for increased catabolism because the effect of LPL was not prevented by inhibitors of LPL's enzymatic activity, p-nitrophenyl N-dodecylcarbamate or phenylmethylsulfonyl fluoride. However, the effect was abolished by boiling LPL prior to the assay suggesting that major structural features of LPL were required. Also, LPL-induced binding to cells was blocked by an anti-LPL monoclonal antibody but not by antibodies that are known to block apolipoprotein E- or B-100-mediated binding to low density lipoprotein (LDL) receptors. This indicates that LPL itself mediated 125I-lipoprotein binding to cells. Cellular degradation of 125I-lipoproteins was partially or completely blocked by two previously described ligands for the LDL receptor-related protein/alpha 2-macroglobulin receptor (LRP): activated alpha 2-macroglobulin (alpha 2M*), and the 39-kDa receptor-associated protein. These data implicated LRP as mediating LPL-induced lipoprotein degradation and were confirmed by showing that LPL's effects were prevented by an immunoaffinity-isolated polyclonal antibody against LRP. Furthermore, LPL promoted binding of 125I-lipoproteins to highly purified LRP in a solid-phase assay. Heparin or heparinase treatment of cells markedly decreased LPL-induced binding, uptake, and degradation of lipoproteins, but had no effect on catabolism of alpha 2M*. Thus, cell-surface proteoglycans were obligatory participants in the effects of LPL but were not required for LRP-mediated catabolism of alpha 2M*. Taken together, these in vitro findings establish that through interaction with cell-surface proteoglycans, LPL induces catabolism of normal human triglyceride-rich lipoproteins via LRP.     

Path dependencies and defensive routines in Finnish city-regional land-use policy cooperation: case Ristikytö

The article seeks to explain the factors preventing the emergence of a broader city-regional view in land-use policy, in a Finnish urban region fragmented institutionally by several municipalities that have high independence in determining their own land-use policies. The ongoing municipal reform by the Finnish government acknowledges the importance of urban regions in global competitiveness and economic livelihood, and thus it encourages municipalities in urban regions to merge, in order to avoid their counterproductive mutual competition over investments and residents, and related municipal tax income. However, such pressure by the central government has often resulted in evasive manoeuvres and superficial city-regional rhetoric at the level of local governments, with a hidden motivation of maintaining the status quo of inter-municipal competition. As a theoretical framework to explain this phenomenon, the theoretical insights on path dependence and defensive routines are combined. Regarding empirical material, the article focuses on the case of Ristikytö in the intersection between three municipalities in Central Uusimaa, 35?km north of Helsinki.     

Augmentation of blood flow through cerebral collaterals by inhibition of nitric oxide synthase

We examined the influence of nitric oxide (NO) on normal and collateral cerebral blood flow after occlusion of the middle cerebral artery (MCA). Effects of NG-nitro-L-arginine (nitroarginine), an inhibitor of NO synthase, were examined during normotension and hypotension (arterial pressure, 50 mm Hg) in 49 anesthetized dogs. Following a craniotomy, a branch of the MCA was cannulated, and collateral-dependent tissue was identified using the shadow-flow technique. Regional cerebral blood flow was measured with microspheres, and pial artery pressure was measured with a micropipette. Intravenous nitroarginine reduced blood flow to normal cerebrum by approximately 40% (p < 0.05) during normotension and hypotension, with aortic pressure maintained constant after nitroarginine administration. Injection of nitroarginine during hypotension, without control of pressor effects, increased aortic and pial artery pressure approximately twofold. Concurrently, blood flow to normal cerebrum decreased (p < 0.05), while flow to collateral-dependent cerebrum increased (p < 0.05). Phenylephrine was infused during hypotension to increase arterial pressure to values similar to those achieved following nitroarginine. Blood flow to collateral-dependent cerebrum increased (p < 0.05), but flow to normal cerebrum was not altered during infusion of phenylephrine. Thus, inhibition of NO synthase during hypotension increases arterial pressure, decreases blood flow to normal cerebrum, and increases blood flow to collateral-dependent cerebrum. Phenylephrine also increases perfusion pressure and blood flow to collateral-dependent cerebrum, but in contrast to nitroarginine, it does not redistribute blood flow from normal cerebrum.     

Effect of polyglycolic acid membrane on bone regeneration around titanium implants inserted in bone sockets

An experimental animal model was used to evaluate the value of resorbable, non-permeable polyglycolic acid (PGA) membranes in relation to fixtures implanted into simulated extraction sockets. Brånemark fixtures (length 7.0 mm, diameter 3.75 mm) were implanted into edentulous areas of maxillary bone in six sheep. Five fixtures were covered with 0.15-mm-thick PGA membrane (Biofix^®) held in place with a cover screw (PGA group) and five were implanted without membrane (control group). The animals were killed after 4 months and undecalcified mesiodistal sections were prepared from resected jaw specimens. Histomorphometry was used to measure the distance from the shoulder of the fixture to the level of intimate bone contact (SB distance). SB distance was found to be greater in the PGA than in the control group in relation both to the mesial (1.44 ± 0.88 mm versus 0.96 ± 0.47 mm) and distal (1.13 ± 0.80 mm versus 0.77 ± 0.63 mm) aspects of implants. This statistically not significant difference in bone regeneration between the two groups is related to the physical properties of the PGA membrane used.     

Autothermal reforming of n-dodecane, toluene, and their mixture on mono- and bimetallic noble metal zirconia catalysts

Autothermal reforming (ATR) of higher hydrocarbons and their mixture was studied on zirconia-supported mono- (Rh, Pd, or Pt) and bimetallic (RhPt) catalysts. ATR reactions predominated on Rh-containing catalysts at 700–900 °C, whereas thermal cracking predominated on Pt and the support. The thermal stability of Rh was improved when Rh was combined with Pt in the bimetallic catalyst.     

Application of Microreactors in the Dehydrogenation of Isobutane

Microreactors with chromia/alumina catalyst were investigated in isobutane dehydrogenation. Chromia was deposited in the reactor by atomic layer deposition (ALD). Conversion increased with chromium content in the reactor and isobutene selectivity was higher than with conventional powder catalyst. Thermal reactions were negligible making microreactors attractive for measuring kinetic data.     

Detergent impurity effect on recycled HDPE: Properties after repetitive processing

High density polyethylene (rHDPE) is extruded 1 to 8 times, with and without detergent, to simulate the effects of impurities on the material and on the artificial ageing process. The mechanical properties, thermal stability, rheology, Fourier transform infrared spectroscopy (FTIR), and volatile organic compound (VOC) emissions are measured. According to the results, ageing of rHDPE increases tensile strength, reduces elongation, and enhances side chain branching of the material and thus causes rheological changes. The addition of detergent reduces changes in mechanical properties and rheological behavior but accelerates thermal degradation. VOC and FTIR measurements of the samples with detergent addition show generation of harmful 1,4‐dioxane. The amount of total emission, as well as emissions of important perfumes limonene and 1R‐α‐pinene, decreases during multiple extrusion cycles. Heating of the plastics is found to be a major factor in the VOC emission reduction. Impurities have a notable effect on the artificial ageing results. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43766.