Spin Filtering through Single‐Wall Carbon Nanotubes Functionalized with Single‐Stranded DNA

High spin polarization materials or spin filters are key components in spintronics, a niche subfield of electronics where carrier spins play a functional role. Carrier transmission through these materials is “spin selective,” that is, these materials are able to discriminate between “up” and “down” spins. Common spin filters include transition metal ferromagnets and their alloys, with typical spin selectivity (or, polarization) of ≈50% or less. Here carrier transport is considered in an archetypical one‐dimensional molecular hybrid in which a single wall carbon nanotube (SWCNT) is wrapped around by single stranded deoxyribonucleic acid (ssDNA). By magnetoresistance measurements it is shown that this system can act as a spin filter with maximum spin polarization approaching ≈74% at low temperatures, significantly larger than transition metals under comparable conditions. Inversion asymmetric helicoidal potential of the charged ssDNA backbone induces a Rashba spin‐orbit interaction in the SWCNT channel and polarizes carrier spins. The results are consistent with recent theoretical work that predicted spin dependent conductance in ssDNA‐SWCNT hybrid. Ability to generate highly spin polarized carriers using molecular functionalization can lead to magnet‐less and contact‐less spintronic devices in the future. This can eliminate the conductivity mismatch problem and open new directions for research in organic spintronics.     

Iron Oxide Enhanced Chlorine Decay and Disinfection By-Product Formation

This study investigates the interaction of natural organic matter with iron oxide (goethite) on chlorine decay, disinfection by-product (DBP) formation, and DBP compound speciation [total trihalomethanes (TTHM4) and haloacetic acids (HAA5)]. Batch experiments were conducted with goethite, multiple finished drinking waters, variable chlorine dose, and fixed pH 8. The overall objective was to assess natural organic matter (NOM) adsorption onto goethite and its effect on chlorine decay and DBP formation. Chlorine consumption always increased in the presence of goethite and is attributed to an increase in the reactivity and/or modification of adsorbed NOM. Adsorbed NOM also led to an overall increase in TTHM4, however, HAA5 formation was suppressed during the first 2?h. Chloroform was identified as the increasing species and dichloracetic acid was identified as the suppressed species. This study clearly shows that goethite, which is the predominant iron oxide of pipe deposits, alters both chlorine decay and DBP formation and should be considered when assessing water treatment plant operations and DBP monitoring site selection.     

The effects of levcromakalim and pinacidil on the human internal mammary artery

The present study was undertaken to examine the effects of pinacidil and levcromakalim, two potassium, channel openers, on human internal mammary artery (HIMA) obtained from patients undergoing coronary artery bypass surgery, and to clarify the contribution of different K+ channel subtypes in pinacidil and levcromakalim action in this blood vessel. Pinacidil and levcromakalim induced a concentration-dependent relaxation of the precontracted arterial segments (pEC50 = 5.77 +/- 0.05 and 6.89 +/- 0.03, respectively), 4-Aminopyridine (3 mM), a non-selective blocker of K+ channels, induced significant shifts to the right of the concentration-response curves for pinacidil and levcromakalim. Tetraethylammonium (6 mM), charybdotoxin (0.4 microM) and apamin (0.1 microM), blockers of Ca(2+)-sensitive K+ channels, had no effect on the pinacidil- and levcromakalim-evoked relaxation. Glibenclamide (0.1-10 microM), a selective blocker of adenosine triphosphate (ATP)-sensitive K+ channels, competitively antagonized the response to levcromakalim (pKB = 7.92 +/- 0.07). In contrast, glibenclamide, in significantly higher concentrations (3-30 microM), non-competitively antagonized the response to pinacidil. High concentrations of pinacidil (> 10 microM) relaxed arterial rings bathed by a medium containing 100 mM K+ with maximum response 83 +/- 6%. Under the same conditions, the maximum levcromakalim-induced relaxation on HIMA was almost abolished (15 +/- 2%). It is concluded that pinacidil and levcromakalim do not relax the HIMA through the same subtype of K+ channel. ATP-sensitive K+ channels are probably involved in levcromakalim- but not in a pinacidil-induced relaxation in the HIMA. In addition, in pinacidil-induced relaxation of the HIMA, K+ channel-independent mechanisms seem to be involved.     

FIBER-MODIFIED SCALING IN HEAT TRANSFER FOULING MITIGATION

The study of heat exchanger fouling using supersaturated calcium sulphate solutions has been widely reported. In this study fouling was investigated in a larger-scale heat exchange apparatus using stainless-steel pipe, and data were obtained at different flow rates, concentrations and temperature differences. The deposits were examined using a scanning electron microscope, X-ray diffraction and conventional photography. In a novel approach, wood pulp fibers were added to the fouling solution at various concentrations to mitigate fouling. Heat transfer enhancement above the solution-alone was observed initially and the onset of fouling delayed. When fouling eventually developed the final asymptotic level was lower than the fiber-free case for the experimental conditions specified. At a fiber concentration of 0.15% heat transfer augmentation occurred for 11 days. However, at 0.25% fiber concentration, heat transfer augmentation (no fouling) was sustained over the experimental duration of 45 days. It can be concluded that the service-life cycle of a heat exchanger can be prolonged with the addition of asymmetric, flexible, natural fibers. In this work it is argued that fibers modify the onset of deposition by boundary layer scavenging, and interact with turbulent eddies to reduce the rate of mass transfer of the foulant to the heated surface. When scale forms, the crystalline structure of the scale is interrupted by the fibers, which appear to roughen the heat transfer surface initially and increase the heat transfer coefficient. However, the scale deposit continues to build up very slowly, causing the thermal resistance to eventually override the turbulence augmented heat transfer effect of the fibers.     

Experiments on the synthesis of the pyrethrins. XIV.—Rethrins and the cyclopentadienone related to 3-methylcyclopent-2-enone

Dimeric 3-methylcyclopentadienone was obtained by dehydrobromination of 4-bromo-3-methylcyclo-pentenone and by hydrolysis of 4-hydroxy-3-methylcyclopentenone formate. Four structures for the dimer were possible. Synthesis and spectroscopic evidence showed that the dimer obtained was formed by addition to the unsubstituted double bond, with the methyl group on the norbornene ring in the position more remote from the carbonyl group of the cyclopentenone. Decarbonmonoxylation of the dimer gave 3,5-dimethylindanone, synthesised for comparison by another route. Contrary to an earlier report, pyrolysis of 9,10-dihydro-9,10(4,5-3-methylcyclopent-2-enono)anthracene (obtained by alkaline cyclisation of the adduct of anthracene and diacetyl ethylene) gave mainly 3,5-dimethylindanone and not 3-methylcyclopentadienone. Rethrins with no side chain in the alcoholic part of the molecule were synthesised from 4-bromo-3-methylcyclopent-2-enone. Allethrolone cyclopropane carboxylate was made for comparison of its insecticidal activity with allethrolone chrysanthemate.     

Glass microparticle- versus microsphere-filled experimental dental adhesives

This study aimed to formulate antibacterial dental adhesives. Phosphate-substituted methacrylate adhesives were modified with 0–20 wt % copper-doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle-filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle-filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere-filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere-filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate-substituted methacrylate filled with glass could be used as an antibacterial adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47832.     

Optimization of E. coli tip-sonication for high-yield cell-free extract using finite element modeling

Optimal tip sonication settings, namely tip position, input power, and pulse durations, are necessary for temperature sensitive procedures like preparation of viable cell extract. In this paper, the optimum tip immersion depth (20–30% height below the liquid surface) is estimated which ensures maximum mixing thereby enhancing thermal dissipation of local cavitation hotspots. A finite element (FE) heat transfer model is presented, validated experimentally with (R² > 97%) and used to observe the effect of temperature rise on cell extract performance of Escherichia coli BL21 DE3 star strain and estimate the temperature threshold. Relative yields in the top 10% are observed for solution temperatures maintained below 32°C; this reduces below 50% relative yield at temperatures above 47°C. A generalized workflow for direct simulation using the CONSOL code as well as master plots for estimation of sonication parameters (power input and pulse settings) is also presented.     

Improving Routine Immunization Coverage Through Optimally Designed Predictive Models

Routine immunization (RI) of children is the most effective and timely public health intervention for decreasing child mortality rates around the globe. Pakistan being a low-and-middle-income-country (LMIC) has one of the highest child mortality rates in the world occurring mainly due to vaccine-preventable diseases (VPDs). For improving RI coverage, a critical need is to establish potential RI defaulters at an early stage, so that appropriate interventions can be targeted towards such population who are identified to be at risk of missing on their scheduled vaccine uptakes. In this paper, a machine learning (ML) based predictive model has been proposed to predict defaulting and non-defaulting children on upcoming immunization visits and examine the effect of its underlying contributing factors. The predictive model uses data obtained from Paigham-e-Sehat study having immunization records of 3,113 children. The design of predictive model is based on obtaining optimal results across accuracy, specificity, and sensitivity, to ensure model outcomes remain practically relevant to the problem addressed. Further optimization of predictive model is obtained through selection of significant features and removing data bias. Nine machine learning algorithms were applied for prediction of defaulting children for the next immunization visit. The results showed that the random forest model achieves the optimal accuracy of 81.9% with 83.6% sensitivity and 80.3% specificity. The main determinants of vaccination coverage were found to be vaccine coverage at birth, parental education, and socio-economic conditions of the defaulting group. This information can assist relevant policy makers to take proactive and effective measures for developing evidence based targeted and timely interventions for defaulting children.     

Pikeperch,Sander lucioperca Invasion in the Neretva River Watershed (Bosnia and Herzegovina,Croatia) After Alteration of River Flow

The invasion history and the recent distribution, abundance and prey composition of pikeperch, Sander lucioperca in Neretva River watershed (Bosnia and Herzegovina and Croatia) are presented. The species was illegally/unintentionally introduced in Ramski Reservoir in the upper river part in 1986, while establishment of its abundant populations was reported during the 1990s in two connected artificial reservoirs. The research on the present abundance and food composition was executed during the 2012–2014 period. The results showed that pikeperch occupied most of the water bodies of the Neretva River, with an exception of natural river parts with gravel sediment and fast flow: all five artificial reservoirs (Ramski, Jablani?ki, Grabovica, Salakovac and Mostarski reservoirs) and lower wetland zone. However, the success and impact of colonization differ among water bodies, indicating pikeperch preference for warm and shallow reservoirs. Pikeperch prey is composed of different fish species abundant in specific water bodies. In artificial reservoirs, it preys mostly on introduced fish species, with a potential for controlling pumpkinseed abundance and biomass. Sampling carried out in Ramski Reservoir between 2013 and 1014 showed exclusive feeding on the introduced Leucaspius delineatus, and the establishment of a new food web, where only introduced species play significant roles. Copyright © 2015 John Wiley & Sons, Ltd.