bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ordered Nanostructures of Carbon Nanotube–Polymer Composites from Lyotropic Liquid Crystal Templating
Authors: Kasprzak Christopher R. , Scherzinger Evan T. , Sarkar Amrita , Miao Miranda , Porcincula Dominique H. , Madriz Alejandro M. , Pennewell Zachary M. , Chau Sophia S. , Fernando Raymond , Stefik Morgan , Zhang Shanju 
Published: August 2018

AbstractA series of polymer nanocomposites containing single‐walled carbon nanotubes (SWNTs) are prepared from polymerizable quaternary ammonium surfactants using photo‐polymerization and investigated by means of polarized optical microscopy, small‐angle X‐ray scattering, and rheological measurements. The surfactant monomers with various alkyl chains of nonpolar tails form lyotropic liquid crystalline (LLC) mesophases in aqueous medium with hexagonal packing of cylindrical micelles. The physical adsorption of nonpolar tails of surfactants on the surface of SWNTs results in de‐bundled nanotubes. The LLC phase diagram is investigated as functions of alkyl chain length, concentration, temperature, and SWNTs. As such, addition of SWNTs does not change the hexagonal mesophases but enhances the order–disorder transition temperatures and alters the rheological behaviors. After photo‐polymerization, the microstructures of hexagonal packing are changed while addition of SWNTs does not disrupt the resulting microstructures. The polymerized composites are consistent with both lamellar and gyroid nanostructures and a possible model is proposed to interpret the observed phenomenon. Under the shear flow, the defect‐free monodomain structures are obtained in the LLC phase and subsequently locked in the solid film after polymerization.
An Efficient Post‐Polymerization Modification of Poly(Styrene‐co‐Maleic Anhydride) for Thermally Reversible Nanocomposites
Authors: Pavía‐Sanders Adriana , Nissen April , O'Bryan Greg 
Published: August 2018

AbstractA copolymer of maleic anhydride and styrene is functionalized with Diels–Alder (DA) capable pendant groups to enable the study of this material with different crosslink densities. This constituent is synthesized using commercially available starting materials and relatively simple and uncomplicated chemistries which open the possibility for its use in large‐scale applications. The 10%, 25%, 50%, and 100% DA nominal crosslinking based on available pendant furan groups on the polymeric component is investigated. The reaction kinetics are monitored using infrared spectroscopy and rheology. Based on the rheological results, carbon nanotube (CNT) incorporation into the DA matrix is explored in order to determine its effects on the complex modulus of the material. This work is meant as a proof of concept for this DA material with the possibility of its incorporation into other commonly used bulk materials and/or adhesives to allow for an easily reversible product formulation.
Intrinsically Tuning the Electromechanical Properties of Elastomeric Dielectrics: A Chemistry Perspective
Authors: Ellingford Christopher , Bowen Christopher , McNally Tony , Wan Chaoying 
Published: August 2018

AbstractDielectric elastomers have the capability to be used as transducers for actuation and energy harvesting applications due to their excellent combination of large strain capability (100–400%), rapid response (10−3 s), high energy density (10–150 kJ m−3), low noise, and lightweight nature. However, the dielectric properties of non‐polar elastomers such as dielectric permittivity εr, breakdown strengthEb, and dielectric loss ε ″, need to be enhanced for real world applications. The introduction of polar groups or structures into dielectric elastomers through covalently bonding is an attractive approach to ‘intrinsically’ induce a permanent polarity to the elastomers, and can eliminate the poor post‐processing issues and breakdown strength of extrinsically modified materials, which have often been prepared by incorporation of fillers. This review discusses the chemical methods for modification of dielectric elastomers, such as hydrosilylation, thiol‐ene click chemistry, azide click chemistry, and atom transfer radical polymerization. The effects of the type and concentration of polar groups on the dielectric and mechanical properties of the elastomers and their performance in actuation and harvesting systems are discussed. State‐of‐the‐art developments and perspectives of modified dielectric elastomers for deformable energy generators and transducers are provided.
Effect of dietary fiber levels on bacterial composition with age in the cecum of meat rabbits
Authors: Wu Zhenyu , Zhou Hailiang , Li Fuchang , Zhang Nanbin , Zhu Yanli 
Published: August 2018

AbstractThis study investigated the influence of dietary fiber levels on the growth performance, digestion, metabolism, and cecal microbial community of rabbits with different diets at different age. The different levels of dietary natural detergent fiber (NDF) were formulated accordingly: 400(A), 350(B), 300(C), 250(D) g/kg original matter basis, respectively; the different ages were 52, 62, and 72 days. With NDF increasing, the average daily feed intake (ADFI) and feed conversion rate (FCR) were increased, whereas average daily gain (ADG) and mortality were decreased (p < 0.05). The stomach relative weight, stomach content relative weight, cecal relative weight, and cecal content weight increased with increasing NDF (p < 0.05). The NH3‐N concentration of cecum dropped when the dietary NDF increased (p < 0.05). The diversity of the total microbiota increased significantly in Diets B, C (p = 0.011), and reached the lowest in 52 days for all diet groups. The richness index was decreased significantly in Diet A, D (p < 0.05) and in 62 days (p < 0.001), respectively. The phylum Firmicutes was higher (p < 0.01) in rabbits fed Diets B, C than Diets A, D and Bacteroidetes was highest in Diets C, D, and Proteobacteria was the highest in Diet A (p < 0.001). Among the classified genera, there were 14 that had levels of abundance of more than 1% and were commonly shared by all samples. Ruminococcus spp. that produced volatile fatty acid (VFA) abundance was highest from Diets B, C at 52 and 62 days. It is interesting to note that Bifidobacterium from Diet C was the most abundant genus during the entire experimental period (p < 0.01). The data from Venn diagrams, principal component analysis (PCA), and heat map plots of the bacterial communities showed that there were more groups of shared microbiota with aging. The above results indicate the cecal microbiota controlled by the 350 g/kg NDF diet can prevent gastrointestinal distress and exhibit good production performance.
RpoN and the Nps and Npa two‐component regulatory system control pilE transcription in commensal Neisseria
Authors: Rendón María A. , Lona Beatriz , Ma Mancheong , So Magdalene 
Published: August 2018

AbstractOver 20 genes are involved in the biogenesis and function of the Neisseria Type IV pilus (Tfp). In the pathogenic species, RpoD and the integration host factor (IHF) protein regulate expression of pilE, encoding the Tfp structural subunit. We previously reported that in commensal species, pilE transcription is regulated by RpoN, IHF, and activator Npa. Npa has many hallmarks of response regulators in two‐component regulatory systems, leading us to search for its response regulator partner. We report that Npa partners with sensor kinase Nps to control pilE transcription. Among the genes involved in Tfp biogenesis and function, only pilE is controlled by RpoN and Npa/Nps. We summarize our findings in a model, and discuss the implications of the differential regulation of pilE the context of Neisseria Tfp biogenesis.
Incidence, Types, and Shedding and Ingestion Times of Metallic Fishing Tackle in the Digestive Systems of White Sturgeon
Authors: Lamansky James A. , Meyer Kevin A. , Bowersox Brett J. , DuPont Joe M. , Bentz Brandon , Lepla Ken B. 
Published: August 2018

Abstract
Over the last decade, fishing tackle has been documented in the digestive tracts of White Sturgeon Acipenser transmontanus in several fisheries in the Columbia River basin, raising concerns about the prevalence and types of tackle being consumed and the ability of these long-lived fish to shed such metal in a timely manner. We scanned 2,077 White Sturgeon with a metal detector and X-rayed (with a portable X-ray system) 443 fish in the Hells Canyon reach of the Snake River to characterize the incidence, quantity, and type of hooks and other metal fishing tackle that had been ingested. We also estimated the amount of time for fish to eliminate ingested metal and to ingest new metal. For the fish we captured, which averaged 118 cm and ranged from 47 to 287 cm (fork length), 21% contained metal in their digestive tract, with smaller fish (&lt;100 cm) less likely to contain metal (10%) than larger fish (&gt;100 cm; 36%). Much of the metal in the digestive systems of White Sturgeon was fishing tackle that was not gear targeting White Sturgeon and included large and small hooks, jigs, swivels, and pieces of broken metal. White Sturgeon with metal in their digestive systems, on average, weighed slightly less than fish without metal, suggesting that metal may slightly hinder food consumption or assimilation, though this affect was apparently short lived. White Sturgeon X-rayed at least twice over the course of the study were able to pass ingested metal on average in 492 d, but one piece of metal was retained for at least 1,266 d. White Sturgeon ingested new metal on average every 575 d. In summary, our results suggest that White Sturgeon effectively process the metal they ingest, and that most if not all their metal passage is by oxidation through the digestive system.
Proton Pump Inhibitors: Risks and Rewards and Emerging Consequences to the Gut Microbiome
Authors: Singh Amandeep , Cresci Gail A. , Kirby Donald F. 
Published: August 2018

AbstractIn recent years, proton pump inhibitors (PPIs) have been criticized for their various adverse interactions and side effects, creating a dilemma among practitioners regarding their use. Our goal is to review the proper use and possible side effects that might be caused by or associated with PPI use. Conclusions were drawn based on the evidence supporting or refuting short‐term and long‐term adverse events associated with PPI use. We also looked for the evidence regarding effects of PPIs on gut microbiota and their overall safety profile. Although there are significant discrepancies in the current literature regarding various adverse effects associated with PPI use, current data suggest that PPI use is not associated with an increased risk of bone fractures, community‐acquired pneumonia, cardiovascular events, hypocalcemia, and gastric malignancies. A mild increased risk of vitamin B12 deficiency and chronic kidney disease, and a moderate increase in the risk of rebound hypersecretion, small intestinal bacterial overgrowth, and enteric infections, including Clostridium difficile, has been noted with PPI therapy. PPI's link with dementia and spontaneous bacterial peritonitis is not clear and requires further investigation. When used appropriately, PPIs are safe medications and are associated with minimal side effects. A clear indication and potential short‐term and long‐term side effects should be considered before starting PPI therapy.
On consistency and energy conservation in smoothed particle hydrodynamics
Authors: Islam Md Rushdie Ibne , Chakraborty Sukanta , Shaw Amit 
Published: August 2018

SummaryEnergy conservation and consistency are not easy to achieve simultaneously in smoothed particle hydrodynamics (SPH). In this study, an efficient strategy is proposed to achieve energy conservation in an SPH framework with a consistent basis function. Herein, at every particle pair interaction, a correction term is introduced such that energy conservation is restored locally and, at the same time, the total variation of different variables due to the correction term is minimum. The final form of the proposed formulation is such that no additional computational effort is required and the simplicity of SPH is preserved. The theoretical error estimate of the proposed formulation is performed. The proposed scheme is also compared with benchmark SPH formulations in terms of the L2 error norm for representative functional derivatives both in regular and irregular particle distributions. Finally, the efficacy of the proposed formulation in conserving energy and maintaining accuracy is demonstrated via few elastic, elastic‐plastic impact and fracture problems.
Mechanochemical Synthesis of Iron and Cobalt Magnetic Metal Nanoparticles and Iron/Calcium Oxide and Cobalt/Calcium Oxide Nanocomposites
Authors: Chaudhary Varun , Zhong Yaoying , Parmar Harshida , Sharma Vinay , Tan Xiao , Ramanujan Raju V. 
Published: August 2018

AbstractWe report an environmentally benign and cost‐effective method to produce Fe and Co magnetic metal nanoparticles as well as the Fe/Cao and Co/CaO nanocomposites by using a novel, dry mechanochemical process. Mechanochemical milling of metal oxides with a suitable reducing agent resulted in the production of magnetic metal nanoparticles. The process involved grinding and consequent reduction of low‐costing oxide powders, unlike conventional processing techniques involving metal salts or metal complexes. Calcium granules were used as the reducing agent. Magnetometry measurements were performed over a large range of temperatures, from 10 to 1273 K, to evaluate the Curie temperature, blocking temperature, irreversibility temperature, saturation magnetization, and coercivity. The saturation magnetizations of the iron and cobalt nanoparticles were found to be 191 and 102 emu g−1, respectively. The heating abilities of these nanoparticles suspended in several liquids under alternating magnetic fields were measured and the specific loss power was determined. Our results suggest that the dry mechanochemical process is a robust method to produce metallic nanoparticles and nanocomposites.
Directly coating silanized nanocrystalline cellulose on carbon fiber for enhancing the interfacial adhesion of carbon fiber/epoxy resin composites
Authors: Zhang Mengjie , Li Ming , Liu Liu , Fu Junsong , Jin Lin , Shang Lei , Xiao Linghan , Ao Yuhui 
Published: August 2018

A continuous coating was used to treat carbon fibers (CFs) with silanized nanocrystalline cellulose (NCC) for enhancing the interfacial adhesion of CF/epoxy composites. The NCC was silanized with 3‐aminopropyltriethoxysilane and then was applied to modify the CF surface for increasing the surface roughness of the CF and achieving chemical bonding between the CF and epoxy resin. The morphologies of the modified CFs with different contents of silanized NCC were characterized by a scanning electron microscope (SEM) and the performance of the silanized NCC‐coated CF/epoxy composites was characterized by an interfacial shear strength (IFSS) test and a flexural test. The experimental results indicated that excessively silanized NCC had reduced interfacial properties due to the agglomeration of NCC. Notably, increases of 94.22% in IFSS and 23.24% in flexural strength were achieved in 0.3 wt% silanized NCC‐coated CF/epoxy composites compared to the desized CF/epoxy composites. As a result, dispersion of silanized NCC in the interface regions was one of the critical factors influencing the interfacial properties of the composites. Coating CFs with silanized NCC provided valuable method based on an abundant raw material for strengthening the interfacial adhesion between CF and epoxy resin matrix. POLYM. COMPOS., 40:E744–E752, 2019. © 2018 Society of Plastics Engineers
Colorimetric Co2+ sensor based on an anionic pyridylazo dye and a cationic polyelectrolyte in aqueous solution
Authors: Inoue Koshiro , Aikawa Shunichi , Sakamaki Masaru , Fukushima Yasumasa 
Published: August 2018

AbstractA new naked‐eye colorimetric sensor for detecting Co2+ in a pure aqueous solution at pH 7.0 was developed by mixing an anionic organic dye, 2‐(5‐bromo‐2‐pyridylazo)‐5‐(N‐propyl‐N‐sulfopropylamino)phenol (5‐Br‐PAPS) with a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC). Upon addition of Co2+, the absorption maximum exhibited a remarkable bathochromic shift from 426 to 635 nm (Δ = 209 nm) with a detectable color change from yellow, green to blue, while other metal ions did not induce such a change. The results showed that the 5‐Br‐PAPS and PDADMAC mixture can be used as a selective and sensitive naked‐eye colorimetric chemosensor for Co2+. This study afforded a simple strategy to construct a novel chemosensor by a simple mixture of an organic dye and an oppositely charged polyelectrolyte. © 2018 Society of Chemical Industry
Some novel nanostructure Schiff base compounds: Antimicrobial and thermal behaviors
Authors: Khani S. , Montazerozohori M. , Naghiha R. 
Published: August 2018

AbstractIn this paper, five new zinc‐Schiff base compounds formulated as ZnLX2 (L is a new N3‐Schiff base ligand obtained by condensation reaction between diethylenetriamine and (Z)‐3‐(4‐(dimethylamino)phenyl) acrylaldehyde and X is (Cl−, Br−, I−, N3−, and NCS−)) were synthesized and characterized by Fourier transform infrared, 1H and 13C NMR, UV–visible, thermal analyses, and molar conductivity measurements. Low molar conductivity values of the compounds in dimethylformamide (DMF) showed nonelectrolyte character of them. Zinc complexes have been also prepared in nanostructure sizes under ultrasonic irradiation confirmed by X‐ray powder diffraction and scanning electron microscopy. Thereafter, ZnO nanoparticles were prepared by direct calcination process of zinc iodide complex at 600°C under air atmosphere. Furthermore, thermogravimetric analyses of the complexes were used for the investigation of thermal behavior of the tiled compounds. Based on TG/DTG plots, some kinetics activation parameters of the compounds at all thermal decomposition steps were calculated. In final, antimicrobial activities of the compounds were investigated by the well diffusion technique against the gram‐positive bacteria of Staphylococcus aureus and Bacillus subtilis, and the gram‐negative bacteria of Escherichia coli and Pseudomonas aeruginosa and the fungi strains of Aspergillus oryzae and Candida albicans. The results showed that all zinc‐Schiff base organic compounds are more antimicrobial active than free ligand.
“Click” generation of a conjugated polymer library for SWNT dispersion
Authors: Li Kelvin , Kardelis Vladimir , Adronov Alex 
Published: August 2018

ABSTRACTNoncovalent functionalization of single‐walled carbon nanotubes (SWNTs) with conjugated polymers enhances SWNT processability and allows for selective dispersion of various SWNT species. Selective dispersions can be obtained by tuning the nature of the polymer, which can involve using various polymer backbones or side‐chains. However, a clear understanding of selectivity determinants is elusive, as the degree of polymerization (DP) has a large effect on SWNT selectivity. Additionally, preparing libraries of conjugated polymers with varying functionality while keeping DP consistent is difficult. Here, we report the utilization of a strained cyclooctyne‐containing conjugated polymer that serves as a versatile scaffold, enabling systematic preparation of a small library of conjugated polymers with different side‐chain functionality, while maintaining a consistent DP. The resulting polymers were used as dispersants for SWNTs, forming supramolecular polymer‐SWNT complexes that were characterized by UV‐Vis‐NIR absorption and Raman spectroscopy. In the series of polymers, we were able to probe the effect of small changes within the side chains, such as the incorporation of a carbonyl group or an aromatic unit, on the quality of the polymer‐SWNT dispersion. The results of these studies provide new insight into the factors that dictate the ability of a polymer to form strong interactions with SWNTs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2053–2058
Visible‐light induced RAFT polymerization of styrenic monomers with aromatic aldehydes as organophotoredox catalysts
Authors: Yang Qian , Zhang Xianhong , Ma Yuhong , Chen Dong , Yang Wantai 
Published: August 2018

ABSTRACTA photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization of p‐methylstyrene (p‐MS) and styrene (St) with 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid as the chain transfer agent (CTA) and aromatic aldehydes, including 4‐cyanobenzaldehyde (PC1), 2,4‐dimethoxy benzaldehyde, and 4‐methoxy benzaldehyde, as organic photocatalysts has been demonstrated via irradiation with 23 W compact fluorescent lamps. The kinetics of the polymerizations shows first order with respect to monomer conversions. Linear evolution of the Mn of the produced polymers with the monomer conversion is observed. Meanwhile, the as‐prepared polymers are of relatively narrow polydispersity (PDI = Mw/Mn). For instance, the polymerization of p‐MS shows living polymerization features using PC1 within a range of solvents. Especially, the Mn of PpMS increased from about 2100 to 12,700 g/mol with the monomer conversion from 8% to 52% in tetrahydrofuran. The controlled polymerization of St is also observed under optimal reaction conditions. However, the Mn discrepancy between the experimental readings and theoretical calculations is greater at the monomer conversions greater than 40% and the PDI increased gradually over the monomer conversion. This is probably because that CTA is strongly sensitive to the light irradiation with wave range around its characteristic absorption wavelength, leading to significant decomposition of CTA moieties during the RAFT polymerization. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2072–2079
pH and reduction dual‐stimuli‐responsive PEGDA/PAMAM injectable network hydrogels via aza‐michael addition for anticancer drug delivery
Authors: Patil Sachin S. , Shinde Vishnu S. , Misra R. Devesh K. 
Published: August 2018

ABSTRACTA pH and reduction dual‐stimuli‐responsive PEGDA/PAMAM injectable network hydrogel containing “acetals” as pH‐sensitive groups and “disulfides” as reducible linkages was designed and synthesized via aza‐Michael addition reaction between PAMAM and PEGDA diacrylates. The pore size and swelling ratio of hydrogels was varied from 14 ± 3 to 19 ± 4 μm and 214 ± 13 to 300 ± 19 μm, respectively, with varying ethylene glycol repeating units in diacrylates. The swelling ratio of PEGDA/PAMAM network hydrogel increased with increase in the molecular weight of PEG and with decrease in pH. The presence of different cationizable amino‐functionalities in PEGDA/PAMAM network hydrogel helped to enhance the swelling ability of hydrogel under the acidic conditions. The continuous increase in metabolically active live HeLa cells with time in MTT assay implied biocompatibility/noncytotoxicity of the synthesized PEGDA/PAMAM injectable network hydrogel. Furthermore, the prepared PEGDA/PAMAM hydrogel showed higher degradation at lower pH and at higher concentration of DTT. The burst release of doxorubicin from PEGDA/PAMAM hydrogel under the environment of the lower pH and in presence of DTT compared to the release at normal physiological pH and in absence of DTT suggested the potential ability of this model hydrogel system for targeted and selective anticancer drug release at tumor tissues. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2080–2095