Zinc toxicity stimulates microbial production of extracellular polymers in a copiotrophic acid soil

The production of extracellular polymeric substances (EPS) is crucial for biofilm structure, microbial nutrition and proximal stability of habitat in a variety of environments. However, the production patterns of microbial EPS in soils as affected by heavy metal contamination remain uncertain. Here we investigate the extracellular response of the native microbial biomass in a grassland soil treated with refined glycerol or crude unrefined biodiesel co-product (BCP) with and without ZnCl2. We extracted microbial EPS and more readily soluble microbial products (SMP), and quantified total polysaccharide, uronic acid, and protein content in these respective extracts. Organic addition, especially BCP, significantly stimulated the production of EPS-polysaccharide and protein but had no impact on EPS-uronic acids, while in the SMP-fraction, polysaccharides and uronic acids were both significantly increased. In response to the inclusion of Zn2+, both EPS- and SMP-polysaccharides increased. This implies firstly that a tolerance mechanism of soil microorganisms against Zn2+ toxicity exists through the stimulation of SMP and EPS production, and secondly that co-products of biofuel industries may have value-added use in bioremediation efforts to support in-situ production of microbial biopolymers. Microbial films and mobile polymers are likely to impact a range of soil properties. The recent focus on EPS research in soils is anticipated to help contribute an improved understanding of biofilm dynamics in other complex systems - such as continuously operated bioreactors

Distance-redshift from an optical metric that includes absorption

We show that it is possible to equate the intensity reduction of a light wave caused by weak absorption with a geometrical reduction in intensity caused by a "transverse" conformal transformation of the spacetime metric in which the wave travels. We are consequently able to modify Gordon's optical metric to account for electromagnetic properties of ponderable material whose properties include both refraction and absorption. Unlike refraction alone however, including absorption requires a modification of the optical metric that depends on the eikonal of the wave itself. We derive the distance-redshift relation from the modified optical metric for Friedman-Lema\^itre-Robertson-Walker spacetimes whose cosmic fluid has associated refraction and absorption coefficients. We then fit the current supernovae data and provide an alternate explanation (other than dark energy) of the apparent acceleration of the universe.Comment: 2 figure

Directed Irradiation Synthesis as an Advanced Plasma Technology for Surface Modification to Activate Porous and “as-received” Titanium Surfaces

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porousand“as-received”c.p. Tisur faces with the aim of improving cellular viability. Nano features were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0◦ to 75◦ degrees, and fluences up to 5.0×1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.Department of Defense (Spain) contract W81XWH-11-2-0067Ministry of Economy and Competitiveness of Spain grant MAT2015-71284-

Do two large gaps signify double-pomeron exchange?

We investigate in what sense the Pomeron can occur more than once in a single process by estimating the single-Pomeron contribution to the double-Pomeron-exchange-like processes and comparing with the experimental data. From this comparison, we find that the double-Pomeron contribution may be much smaller than the previous theoretical estimates. Further theoretical investigation and experimental tests are suggested and discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21844/1/0000247.pd

Subintimal angioplasty of chronic total occlusion in iliac arteries: A safe and durable option

BackgroundTraditionally, aortobifemoral bypass has been the intervention of choice for iliac artery chronic total occlusions (CTOs). However, it is associated with significant morbidity and mortality, limiting its use in high-risk patients. To reduce procedural risk, subintimal angioplasty (SIA) for femoropopliteal CTO has been utilized by many, but few have extended this endovascular technique to treating iliac artery CTOs. We present our experience with 101 successful SIAs for iliac artery CTOs.MethodsA retrospective review of consecutive patients with iliac artery CTOs treated with subintimal angioplasty from June 2000 to January 2009 was completed. Demographic and risk factor data were obtained, along with procedural data. Primary and secondary patency, survival, freedom from claudication, and limb salvage rates were determined by Kaplan-Meier survival analysis. Univariate and multivariate analyses were completed to identify factors adversely affecting primary patency.ResultsOne hundred twenty patients underwent an attempted SIA of an iliac artery CTO, and 101 iliac artery CTOs were successfully treated, giving a technical success rate of 84%. Technical failure was due to the inability to re-enter the lumen in all cases. Indications for intervention were lifestyle-altering claudication in 64 patients (63%) and critical limb ischemia (CLI), in 37 (37%). Eighty-five patients underwent percutaneous SIA, while 11 patients underwent a combined SIA with surgical outflow procedure. Lesions were classified as TransAtlantic InterSociety Consensus (TASC) B, 39 (39%); TASC C, 27 (27%); and TASC D, 35 (35%). In 82 (81%) lesions, stents were deployed with an average of 1.2 (range, 0-3) stents utilized. A re-entry device was used in 14 (14%) lesions. Major complication rate was 3.0%, with a 30-day mortality rate of 1.0%. Primary and secondary patency rates at 1, 2, and 3 years were 86% and 94%, 76% and 92%, and 68% and 80%, respectively. Survival rate was 67% at 5 years, reflecting the poor health of this cohort. Limb salvage for CLI patients at 1 and 5 years was 97% and 95%, respectively. Freedom from claudication at 1 and 3 years was 89% and 73%. Univariate analysis identified hyperlipidemia, coronary artery disease, and prior surgical bypass in treated limb as factors for loss of primary patency; however, on multivariate analysis, no factors remained statistically significant.ConclusionThis study demonstrates that SIA of iliac CTOs is feasible and can be performed safely and effectively, even in high-risk patients. Excellent patency and limb salvage rates can be achieved. In our experience, the safety and durability of SIA makes it an attractive first-line therapy for iliac artery occlusive disease

Tunable Correlated Chern Insulator and Ferromagnetism in Trilayer Graphene/Boron Nitride Moir\'e Superlattice

Studies on two-dimensional electron systems in a strong magnetic field first revealed the quantum Hall (QH) effect, a topological state of matter featuring a finite Chern number (C) and chiral edge states. Haldane later theorized that Chern insulators with integer QH effects could appear in lattice models with complex hopping parameters even at zero magnetic field. The ABC-trilayer graphene/hexagonal boron nitride (TLG/hBN) moir\'e superlattice provides an attractive platform to explore Chern insulators because it features nearly flat moir\'e minibands with a valley-dependent electrically tunable Chern number. Here we report the experimental observation of a correlated Chern insulator in a TLG/hBN moir\'e superlattice. We show that reversing the direction of the applied vertical electric field switches TLG/hBN's moir\'e minibands between zero and finite Chern numbers, as revealed by dramatic changes in magneto-transport behavior. For topological hole minibands tuned to have a finite Chern number, we focus on 1/4 filling, corresponding to one hole per moir\'e unit cell. The Hall resistance is well quantized at h/2e2, i.e. C = 2, for |B| > 0.4 T. The correlated Chern insulator is ferromagnetic, exhibiting significant magnetic hysteresis and a large anomalous Hall signal at zero magnetic field. Our discovery of a C = 2 Chern insulator at zero magnetic field should open up exciting opportunities for discovering novel correlated topological states, possibly with novel topological excitations, in nearly flat and topologically nontrivial moir\'e minibands.Comment: 16 pages, 4 figures, and 2 extended figure

Synthesis of Chiral Polyaniline Films via Chemical Vapor Phase Polymerization

Electrically and optically active polyaniline films doped with (1R)-(-)-10-camphorsulfonic acid were successfully deposited on nonconductive substrates via chemical vapor phase polymerization. The above polyaniline∕R-camphorsulfonate films were characterized by electrochemical and physical methods, such as cyclic voltammetry (CV), UV-vis spectroscopy, four-point probe conductivity measurement, Raman spectroscopy, circular dichroism spectroscopy, and scanning electron microscopy. The poly aniline films grown by this method not only showed high electrochemical activity, supported by CV and Raman spectrum, but also exhibited optical activity corresponding to the polymer chains as observed by circular dichroism spectra

Probing Cosmic Dust of the Early Universe through High-Redshift Gamma-Ray Bursts

We explore the extinction properties of the dust in the distant universe through the afterglows of high-redshifted GRBs based on the "Drude" model which, unlike previous studies, does not require a prior assumption of template extinction laws. We select GRB070802 at z~2.45 (which shows clear evidence for the 2175\AA extinction bump) and GRB050904 at z~6.29, the 2nd most distant GRB observed to date. We fit their afterglow spectra to determine the extinction of their host galaxies. We find that (1) their extinction curves differ substantially from that of the Milky Way, the Small and Large Magellanic Clouds (which were widely adopted as template extinction laws in literature); (2) the 2175\AA extinction feature appears to be also present in GRB050904 at z~6.29; and (3) there does not appear to show strong evidence for a dependence of dust extinction on redshifts. The inferred extinction curves are closely reproduced in terms of a mixture of amorphous silicate and graphite, both of which are expected supernova condensates and have been identified in primitive meteorites as presolar grains originating from supernovae (which are considered as the main source of dust at high-z).Comment: 14 pages, 3 figures, 2 tables; accepted for publication in the Astrophysical Journal Letter