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Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: The black mat enigma
Mahaney, W.C.,Kalm, V.,Krinsley, D.H.,Tricart, P.,Schwartz, S.,Dohm, J.,Kim, K.J.,Kapran, B.,Milner, M.W.,Beukens, R.,Boccia, S.,Hancock, R.G.V.,Hart, K.M.,Kelleher, B. Elsevier 2010 Geomorphology Vol.116 No.1
<P><B>Abstract</B></P><P>A carbon-rich black layer encrusted on a sandy pebbly bed of outwash in the northern Venezuelan Andes, previously considered the result of an alpine grass fire, is now recognized as a ‘black mat’ candidate correlative with Clovis Age sites in North America, falling within the range of ‘black mat’ dated sites (~12.9ka cal BP). As such, the bed at site MUM7B, which dates to <11.8ka <SUP>14</SUP>C years BP (raw dates) and appears to be contemporaneous with the Younger Dryas (YD) cooling event, marks a possibly much more extensive occurrence than previously identified. No fossils (megafauna) or tool assemblages were observed at this newly identified candidate site (3800a.m.s.l.), as in the case of the North American sites. Here, evidence is presented for an extraterrestrial impact event at ~12.9ka. The impact-related Andean bed, located ~20cm above 13.7–13.3ka cal BP alluvial and glaciolacustrine deposits, falls within the sediment characteristics and age range of ‘black mat’ dated sites (~12.9ka cal BP) in North America. Site sediment characteristics include: carbon, glassy spherules, magnetic microspherules, carbon mat ‘welded’ onto coarse granular material, occasional presence of platinum group metals (Rh and Ru), planar deformation features (pdfs) in fine silt-size fragmental grains of quartz, as well as orthoclase, and monazite (with an abundance of Rare Earth Elements—REEs). If the candidate site is ‘black mat’, correlative with the ‘black mat’ sites of North America, such an extensive occurrence may support the hypothesized airburst/impact over the Laurentide Glacier, which led to a reversal of Allerød warming and the onset of YD cooling and readvance of glaciers. While this finding does not confirm such, it merits further investigation, which includes the reconnaissance for additional sites in South America. Furthermore, if confirmed, such an extensive occurrence may corroborate an impact origin.</P>
PHYSIOLOGY OF DIGESTION OF UREA-TREATED RICE STRAW IN SWAMP BUFFALO
Hart, F.J.,Wanapat, M. Asian Australasian Association of Animal Productio 1992 Animal Bioscience Vol.5 No.4
Four rumen-fistulated swamp buffaloes steers were used in a change-over experiment. This experiment was designed to provide a comparison of the effect of urea-ammonia treatment of rice straw with untreated rice straw. Nitrogen, mineral and trace elements were supplied at adequate levels to both diets in order to overcome deficiencies which may have otherwise confounded a direct comparison. There was a 46% increase in the intake of digestible organic matter (OM) with the urea-ammonia treated diet. This was contributed by a 17% increase in the digestibility of OM and a 25% increase in the voluntary intake of OM. Of the cell wall fraction, the digestibility of hemicellulose increased by the greatest amount (26%). There was an increased rate of passage of particulate matter out of the rumen for the treated straw, along with the increased rate of OM fermentation resulted in a 9% decrease in the amount of digesta dry matter (DM) contained in the rumen. The volatile fatty acid (VFA) pool in the rumen was 24% higher for the treated diet.
Inhibitor of MYC identified in a Kröhnke pyridine library
Hart, Jonathan R.,Garner, Amanda L.,Yu, Jing,Ito, Yoshihiro,Sun, Minghao,Ueno, Lynn,Rhee, Jin-Kyu,Baksh, Michael M.,Stefan, Eduard,Hartl, Markus,Bister, Klaus,Vogt, Peter K.,Janda, Kim D. National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.34
<P>In a fluorescence polarization screen for the MYC–MAX interaction, we have identified a novel small-molecule inhibitor of MYC, KJ-Pyr-9, from a Kröhnke pyridine library. The <I>K</I><SUB>d</SUB> of KJ-Pyr-9 for MYC in vitro is 6.5 ± 1.0 nM, as determined by backscattering interferometry; KJ-Pyr-9 also interferes with MYC–MAX complex formation in the cell, as shown in a protein fragment complementation assay. KJ-Pyr-9 specifically inhibits MYC-induced oncogenic transformation in cell culture; it has no or only weak effects on the oncogenic activity of several unrelated oncoproteins. KJ-Pyr-9 preferentially interferes with the proliferation of MYC-overexpressing human and avian cells and specifically reduces the MYC-driven transcriptional signature. In vivo, KJ-Pyr-9 effectively blocks the growth of a xenotransplant of MYC-amplified human cancer cells.</P>
Biocompatible, smooth, plasma-treated nickel-titanium surface--an adequate platform for cell growth.
Chrzanowski, W,Szade, J,Hart, A D,Knowles, J C,Dalby, M J Technomic Pub 2012 Journal of biomaterials applications Vol.26 No.6
<P>High nickel content is believed to reduce the number of biomedical applications of nickel-titanium alloy due to the reported toxicity of nickel. The reduction in nickel release and minimized exposure of the cell to nickel can optimize the biocompatibility of the alloy and increase its use in the application where its shape memory effects and pseudoelasticity are particularly useful, e.g., spinal implants. Many treatments have been tried to improve the biocompatibility of Ni-Ti, and results suggest that a native, smooth surface could provide sufficient tolerance, biologically. We hypothesized that the native surface of nickel-titanium supports cell differentiation and insures good biocompatibility. Three types of surface modifications were investigated: thermal oxidation, alkali treatment, and plasma sputtering, and compared with smooth, ground surface. Thermal oxidation caused a drop in surface nickel content, while negligible chemistry changes were observed for plasma-modified samples when compared with control ground samples. In contrast, alkali treatment caused significant increase in surface nickel concentration and accelerated nickel release. Nickel release was also accelerated in thermally oxidized samples at 600 C, while in other samples it remained at low level. Both thermal oxidation and alkali treatment increased the roughness of the surface, but mean roughness R(a) was significantly greater for the alkali-treated ones. Ground and plasma-modified samples had 'smooth' surfaces with R(a)=4 nm. Deformability tests showed that the adhesion of the surface layers on samples oxidized at 600 C and alkali treatment samples was not sufficient; the layer delaminated upon deformation. It was observed that the cell cytoskeletons on the samples with a high nickel content or release were less developed, suggesting some negative effects of nickel on cell growth. These effects were observed primarily during initial cell contact with the surface. The most favorable cell responses were observed for ground and plasma-sputtered surfaces. These studies indicated that smooth, plasma-modified surfaces provide sufficient properties for cells to grow.</P>
Gitte S. Jensen,Aaron N. Hart,Lue Ann Zaske,Kelly M. Patterson,Christian Drapeau 한국식품영양과학회 2007 Journal of medicinal food Vol.10 No.3
The present research was designed to study the effects of an extract from the edible cyanophyta Aphanizomenonflos-aquaeon human natural killer (NK) cells. We have previously shown, using a double-blind randomized placebo-con-trolled crossover design, that ingestion of 1.5 g of dried whole A. flos-aquaeresulted in a transient reduction in peripheralblood NK cells in 21 healthy human volunteers, suggesting increased NK cell homing into tissue. We have now identified anextract from A. flos-aquae(AFAe) that directly activates NK cells in vitroand modulates the chemokine receptor profile. NKcell activation was evaluated by expression of CD25 and CD69 on CD3. CD56. cells after 18 hours. Changes in CXCR3and CXCR4 chemokine receptor expression after 560 minutes were evaluated by immunostaining and flow cytometry. AFAeinduced the expression of CD69 on CD3. CD56. NK cells, induced CD25 expression on 25% of these cells, and acted insynergy with interleukin 2. NK cells enriched by RosetteSep?? (StemCell Technologies Inc., Vancouver, BC, Canada) werenot activated by AFAe, indicating that the NK activation was dependent on other cells such as monocytes. The low-molecu-lar-weight fraction . 5,000 of AFAe was responsible for the most robust NK cell activation, suggesting novel compounds dif-