bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Field NMR Spectroscopy Reveals Aromaticity‐Modulated Hydrogen Bonding in Heterocycles
Authors: Kakeshpour Tayeb , Bailey John P. , Jenner Madison R. , Howell Darya E. , Staples Richard J. , Holmes Daniel , Wu Judy I. , Jackson James E. 
Published: June 2017

AbstractFrom DNA base pairs to drug–receptor binding, hydrogen (H‐)bonding and aromaticity are common features of heterocycles. Herein, the interplay of these bonding aspects is explored. H‐bond strength modulation due to enhancement or disruption of aromaticity of heterocycles is experimentally revealed by comparing homodimer H‐bond energies of aromatic heterocycles with analogs that have the same H‐bonding moieties but lack cyclic π‐conjugation. NMR studies of dimerization in C6D6 find aromaticity‐modulated H‐bonding (AMHB) energy effects of approximately ±30 %, depending on whether they enhance or weaken aromatic delocalization. The attendant ring current perturbations expected from such modulation are confirmed by chemical shift changes in both observed ring C−H and calculated nucleus‐independent sites. In silico modeling confirms that AMHB effects outweigh those of hybridization or dipole–dipole interaction.
Visible Light Photocatalysis of 6π Heterocyclization
Authors: Münster Niels , Parker Nicholas A. , van Dijk Lucy , Paton Robert S. , Smith Martin D. 
Published: June 2017

AbstractPhoto‐mediated 6π cyclization is a valuable method for the formation of fused heterocyclic systems. Here we demonstrate that irradiation of cyclic 2‐aryloxyketones with blue LED light in the presence of an IrIII complex leads to efficient and high yielding arylation across a panoply of substrates by energy transfer. 2‐Arylthioketones and 2‐arylaminoketones also cyclize effectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state. Subsequent suprafacial 1,4‐hydrogen shift and epimerization leads to the observed cis‐fused products.
Synthesis and characterization of methacrylated star‐shaped poly(lactic acid) employing core molecules with different hydroxyl groups
Authors: Esmaeili Nima , Jahandideh Arash , Muthukumarappan Kasiviswanathan , Åkesson Dan , Skrifvars Mikael 
Published: June 2017

ABSTRACTA set of novel bio‐based star‐shaped thermoset resins was synthesized via ring‐opening polymerization of lactide and employing different multi‐hydroxyl core molecules, including ethylene glycol, glycerol, and erythritol. The branches were end‐functionalized with methacrylic anhydride. The effect of the core molecule on the melt viscosity, the curing behavior of the thermosets and also, the thermomechanical properties of the cured resins were investigated. Resins were characterized by Fourier‐transform infrared spectroscopy, 13C‐NMR, and 1H‐NMR to confirm the chemical structure. Rheological analysis and differential scanning calorimetry analysis were performed to obtain the melt viscosity and the curing behavior of the studied star‐shaped resins. Thermomechanical properties of the cured resins were also measured by dynamic mechanical analysis. The erythritol‐based resin had superior thermomechanical properties compared to the other resins and also, lower melt viscosity compared to the glycerol‐based resin. These are of desired characteristics for a resin, intended to be used as a matrix for the structural composites. Thermomechanical properties of the cured resins were also compared to a commercial unsaturated polyester resin and the experimental results indicated that erythritol‐based resin with 82% bio‐based content has superior thermomechanical properties, compared to the commercial polyester resin. Results of this study indicated that although core molecule with higher number of hydroxyl groups results in resins with better thermomechanical properties, number of hydroxyl groups is not the only governing factor for average molecular weight and melt viscosity of the uncured S‐LA resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45341.
Preparation and characterization of a novel gelatin–poly(vinyl alcohol) hydrogel film loaded with Zataria multiflora essential oil for antibacterial–antioxidant wound‐dressing applications
Authors: Kavoosi Gholamreza , Bordbar Zarrintaj , Dadfar Seyed Mohammadali , Dadfar Seyed Mohammad Mahdi 
Published: June 2017

AbstractThis study was performed to evaluate the properties of poly(vinyl alcohol) (PVA), gelatin, and PVA–gelatin dispersions and films enriched with Zataria multiflora essential oil (ZO). The results reveal that the ζ potential, particle size, and viscosity values and the antioxidant and antibacterial activities of the dispersions changed significantly with the addition of ZO to the polymer matrix. Changes in the properties of the dispersions suggested the presence of interactions between PVA or gelatin and ZO. Such interactions could affect the mechanical and water‐barrier properties of the films. ZO induced remarkable decreases in the tensile strength, elastic modulus, and swelling and increases in the elongation at break, solubility, and water‐vapor permeability of the films. Scanning electron microscopy analyses proved the impact of ZO on the film morphology, which affected the film properties, including the mechanical and water‐barrier properties. The addition of ZO to the polymer led to a coarse film microstructure because of the hydrophobic ZO aggregates, which produced discontinuities in the film matrix. ZO considerably increased the antioxidant and antibacterial activities of the dispersions. Pseudomonas aeruginosa was the most resistant bacteria. The improved antioxidant and antimicrobial activities of the PVA–ZO and gelatin–ZO indicated that such products could effectively be used as wound dressings. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45351.
Comparative analysis of PVA hydrogels incorporating two natural antimicrobials: Punica granatum and Arnica montana tinctures
Authors: Oliveira Renata Nunes , Paranhos da Silva Caio Marcio , Moreira Ana Paula Duarte , Mendonça Roberta Helena , Thiré Rossana Mara da Silva Moreira , McGuinness Garrett Brian 
Published: June 2017

ABSTRACTPoly(vinyl alcohol) (PVA) hydrogels are biocompatible materials that retain relatively high amounts of aqueous fluids in their network. The incorporation of antimicrobial natural products, such as pomegranate and arnica, is a strategy for coupling their bactericidal effects with the favorable properties of the gels for wound healing treatment. The goal of this work was to investigate the microstructural, mechanical, and release properties of PVA–pomegranate and PVA‐arnica samples. Physical interactions were observed by Fourier transform infrared spectra in PVA–pomegranate samples. The addition of pomegranate to PVA led to high Tg, probably related to the physical interactions, and low Tm and Xc, possibly due to the pomegranate location between PVA chains. Increased levels of arnica were associated with a slight decrease in samples' Xc, probably due to a physical barrier imposed by arnica to the interaction of PVA chains. PVA samples presented higher swelling than the samples containing natural products. High amounts of pomegranate in the samples led to high weight loss and high phenols and flavonoids delivery. Arnica release seemed to be more difficult than the pomegranate release. All samples presented relative high mechanical properties. In addition, pomegranate samples present higher potential to deliver active compounds than arnica samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45392.
Composition‐dependent sol‐gel transition of amphiphilic blend of PEG with hydrophobic gallamide components
Authors: Aso Akihiro , Taki Kazutaka , Maeda Tomoki , Toma Kazunori , Tamiaki Hitoshi , Hotta Atsushi 
Published: June 2017

ABSTRACTTwo types of poly(ethylene glycol) (PEG)‐based amphiphiles were synthesized: a diblock‐type amphiphile (PEG1) with a hydrophobic moiety on one terminal of PEG (PEG with the molecular weight of 2000), and a triblock‐type amphiphile (PEG2) with hydrophobic moieties on both terminals of PEG. The hydrophobic moiety consisted of hydrophobic C14 alkyl tails covalently linked through a gallamide component. The sol–gel transitions of the aqueous solution of PEG1 and PEG2 were studied. At the PEG amphiphile concentration of 15 wt %, PEG1 gave a clear solution over a wide temperature range from 20 to 80 °C, while PEG2 was partially soluble in water. However, the aqueous blend solution of PEG1 and PEG2 exhibited a hydrogel depending on the blend ratio and temperature. It was considered that the composition of PEG1 and PEG2 governed the sol–gel transition, and that the dynamic moduli could be effectively controlled by changing the mixing ratios of the PEG amphiphiles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45402.
Poly(vinyl alcohol)/CaCO3‐diacid nanocomposite: Investigation of physical and wetting properties and application in heavy metal adsorption
Authors: Mallakpour Shadpour , Khadem Elham 
Published: June 2017

ABSTRACTPoly(vinyl alcohol) (PVA) nanocomposite and modified CaCO3 nanoparticles (NPs) were fabricated by ultrasound agitation method with particle content altering from 3, 5, and 8 wt %. The CaCO3 surface was successfully treated by 10 wt % of bioactive dicarboxylic acid (DA). The influences of loading modified NPs on the thermal, mechanical, adsorption, contact angle, and physical properties of the poly(vinyl alcohol) nanocomposite films were thoroughly studied. The results showed that incorporation of modified CaCO3 into the PVA matrix had better performance than the pure PVA. Meanwhile, tensile strength, Young's modulus, and thermal stability are enhanced from 33.36 MPa, 1.26 GPs, and 242.918C (neat PVA) to 81.7 MPa, 4.81 GPa, and 312.95 °C (PVA/CaCO3‐DA NC 5 wt %), respectively. Also, the adsorption capacity of the PVA/CaCO3‐DA NCs 5 and 8 wt % revealed that the NC films could act as an appropriate absorbent for the removal of Cd(II) ions with maximum adsorption capacity of about 20.70 and 25.19 mg g−1 for Cd(II), respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45414.
Relaxation dynamic and electrical mobility for poly(methyl methacrylate)‐polyaniline composites
Authors: Moussa Mohammed A. , Ghoneim Ahmed M. , Abdel Rehim Mona H. , Khairy Sherif A. , Soliman Mohamed A. , Turky Gamal M. 
Published: June 2017

ABSTRACTComposites of emeraldine form of polyaniline (PAni) and poly(methyl methacrylate) (PMMA) are prepared by emulsion polymerization method in definite ratios. The chemical structure of the samples and their morphologies have been investigated by different techniques including FTIR, UV–vis, XRD, SEM, and TGA. Enhancement in thermal stability of the obtained composites by PAni additions has been confirmed. Alpha analyzer, in frequency range 0.1 Hz to 20 MHz, was employed to investigate the molecular dynamics of the prepared samples and the accompanied electrical conductivity at temperatures ranging from 223 to 423 K. Conductivity investigations showed that mobility has the more dominant effect on the charge transportation. The dynamic peak at lower temperatures of the PMMA has high activation energy (83.8 kJ/mol). While, Maxwill‐Wagner‐Siller process due to the interfacial polarization in the composites has only 7.5 kJ/mol activation energy. This is a clear indication of the ease of the investigated dynamic. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45415.
Improved enzymatic performance of graphene‐immobilized β‐glucosidase A in the presence of glucose‐6‐phosphate
Authors: Albino Gomes Anderson , Pazinatto Telli Elisa , Miletti Luiz Claudio , Skoronski Everton , Gomes Ghislandi Marcos , Felippe da Silva Gustavo , Borba Magalhães Maria de Lourdes 
Published: June 2017

AbstractOptimization of cellulose enzymatic hydrolysis is crucial for cost‐effective bioethanol production from lignocellulosic biomass. Enzyme immobilization in solid support allows enzyme recycling for reuse, lowering hydrolysis costs. Graphene is a nanomaterial isolated in 2004, which possesses exceptional properties for biomolecule immobilization. This study evaluates the potential for β‐glucosidase recycling by immobilization on graphene nanosheets. Data reported here demonstrated that graphene‐immobilized β‐glucosidase can be recycled for at least eight cycles. Immobilization did not change the optimal temperature of catalysis and improved enzymatic stability upon storage. The role of glucose‐6‐phosphate on immobilized enzyme was also investigated, demonstrating that glucose‐6‐phosphate acts as a mixed‐type activator and improves storage stability of immobilized enzyme. Complete cellulose hydrolysis using graphene‐immobilized β‐glucosidase in the presence of glucose‐6‐phosphate resulted in greatly improved hydrolysis rates, demonstrating the potential of this strategy for biomass hydrolysis.
Neonates with cancer and causes of death; lessons from 615 cases in the SEER databases
Authors: Alfaar Ahmad S. , Hassan Waleed M. , Bakry Mohamed Sabry , Qaddoumi Ibrahim 
Published: June 2017

AbstractNeonatal tumors are rare with no standard treatment approaches to these diseases, and the patients experience poor outcomes. Our aim was to determine the distribution of cancers affecting neonates and compare survival between these cancers and older children.We analyzed SEER data (1973–2007) from patients who were younger than 2 years at diagnosis of malignancy. Special permission was granted to access the detailed (i.e., age in months) data of those patients. The Chi‐square Log‐rank test was used to compare survival between neonates (aged <1 month) and older children (>1 month to <2 years). We identified 615 neonatal cancers (454 solid tumors, 93 leukemia/lymphoma, and 68 CNS neoplasms). Neuroblastoma was the most common neonatal tumor followed by Germ cell tumors. The 5‐year overall survival (OS) for all neonates was 60.3% (95% CI, 56.2–64.4). Neonates with solid tumors had the highest 5‐year OS (71.2%; 95% CI, 66.9–75.5), followed by those with leukemia (39.1%; 95% CI, 28.3–49.9) or CNS tumors (15%; 95% CI, 5.4–24.6). Except for neuroblastoma, all neonatal tumors showed inferior outcomes compared to that in the older group. The proportion of neonates who died from causes other than cancer was significantly higher than that of the older children (37.9% vs. 16.4%; P < 0.0005). In general, the outcome of neonatal cancers has not improved over the last 34 years. The distribution of neonatal cancer is different than other pediatric age groups. Although the progress in neonatal and cancer care over the last 30 years, only death from noncancer causes showed improvement. Studying neonatal tumors as part of national studies is essential to understand their etiology, determine the best treatment approaches, and improve survival and quality of life for those patients.
Improving Carbon‐Coated TiO2 Films with a TiCl4 Treatment for Photocatalytic Water Purification
Authors: Odling Gylen , Ivaturi Aruna , Chatzisymeon Efthalia , Robertson Neil 
Published: June 2017

AbstractBy using a simple thermal decomposition route, carbon‐TiO2 hybrid films have been synthesized from a catechol‐TiO2 surface complex. The coated films display enhanced visible region absorption, owing to the thin (≈2 nm) layer of carbon encapsulating the TiO2. Although photocatalytically active under visible light alone, it is demonstrated that the activity of the carbon‐coated films can be improved further by a hydrolytic treatment with TiCl4, leading to the introduction of small TiO2 particles (5–10 nm) and doping of chlorine into the structure. The combination of the carbon layer and TiCl4 treatment gives increased photocatalytic performance for the photodegradation of dyes, phenolic pollutants and the reduction of toxic CrVI to relatively benign CrIII. In addition, the carbon‐coated films show improved bactericidal activity under UV irradiation, and hence have been successfully tested against the most common types of pollutant present in potential drinking waters.
On the Role of Acidity in Bulk and Nanosheet [T]MFI (T=Al3+, Ga3+, Fe3+, B3+) Zeolites in the Methanol‐to‐Hydrocarbons Reaction
Authors: Meng Lingqian , Zhu Xiaochun , Mezari Brahim , Pestman Robert , Wannapakdee Wannaruedee , Hensen Emiel J. M. 
Published: June 2017

AbstractThe influence of framework substituents (Al3+, Ga3+, Fe3+ and B3+) and morphology (bulk vs. nanometer‐sized sheets) of MFI zeolites on the acidity and catalytic performance in the methanol‐to‐hydrocarbons (MTH) reaction was investigated. The Brønsted acid density and strength decreased in the order Al(OH)Si>Ga(OH)Si>Fe(OH)Si≫B(OH)Si. Pyridine 15N NMR spectra confirmed the differences in the Brønsted and Lewis acid strengths but also provided evidence for site heterogeneity in the Brønsted acid sites. Owing to the lower efficiency with which tervalent ions can be inserted into the zeolite framework, sheet‐like zeolites exhibited lower acidity than bulk zeolites. The sheet‐like Al‐containing MFI zeolite exhibited the greatest longevity as a MTH catalyst, outperforming its bulk [Al]MFI counterpart. Although the lower acidity of bulk [Ga]MFI led to a better catalytic performance than bulk [Al]MFI, the sheet‐like [Ga]MFI sample was found to be nearly inactive owing to lower and heterogeneous Brønsted acidity. All Fe‐ and B‐substituted zeolite samples displayed very low catalytic performance owing to their weak acidity. Based on the product distribution, the MTH reaction was found to be dominated by the olefins‐based catalytic cycle. The small contribution of the aromatics‐based catalytic cycle was larger for bulk zeolite than for sheet‐like zeolite, indicating that shorter residence time of aromatics can explain the lower tendency toward coking and enhanced catalyst longevity.
Partially Acetylated or Benzoylated Arabinose Derivatives as Structurally Simple Organogelators: Effect of the Ester Protecting Group on Gel Properties
Authors: Rajkamal  , Pathak Navendu P. , Halder Tanmoy , Dhara Shubhajit , Yadav Somnath 
Published: June 2017

AbstractSugar‐based low‐molecular‐weight gelators (LMWGs) have been used for various applications for a long time. Herein, structurally simple, ester‐protected arabinosides are reported as low‐molecular‐weight organogelators (LMOGs) that are able to gel aromatic solvents, as well as petrol and diesel. Studies on the mechanical strength of the gels, through detailed rheological experiments, indicate that gels from the 1,2‐dibenzoylated arabinose gelator possess better mechanical properties than those from the 1,2‐diacetylated gelator. These results are interpreted in terms of the tendency of the former to form fibers with comparatively lower diameter than those of the latter, based on detailed field‐emission SEM and AFM studies. Investigations of the interactions responsible for the self‐assembly of gelators through IR spectroscopy and wide‐angle X‐ray scattering reveal that the primary interactions responsible are hydrogen bonds between the hydroxyl groups and ester C=O, which is absent in the solid state of the gelators. In addition, π interactions present in the 1,2‐dibenzoylated derivative result in a more regular arrangement, which, in turn, leads to better mechanical properties of the gels compared with those of the 1,2‐diacetylated gelator.
Regioselective Direct C‐Alkenylation of Indoles
Authors: Petrini Marino 
Published: June 2017

AbstractThe direct introduction of alkenyl groups into the indole framework avoiding its preliminary functionalization can be carried out using different synthetic strategies. Transition‐metal complexes facilitate the C−H activation of indoles or alkenes allowing an efficient Csp2‐ Csp2 bond formation. The hydroindolation of alkynes catalyzed by the same metal complexes or various acidic promoters can also be pursued for the alkenylation process. Conjugate addition of electron‐poor alkenes and direct condensation of carbonyl derivatives with indoles are also of interest for this purpose. The regiochemical control can be exploited using the intrinsic C‐3 reactivity of the indole ring. The introduction of a suitable directing group at the nitrogen atom allows the preparation of C‐2 alkenylated derivatives by transition metal catalyzed reactions. This review collects the fundamental contributions in this field reported in literature during the last fifteen years.
Dimensioning the Term Carbenoid
Authors: Caballero Ana , Pérez Pedro J. 
Published: June 2017

AbstractThe current use of the term carbenoid is discussed, particularly in the context of carbene transfer reactions from diazo compounds, in which intermediates of type LnM=CR1R2, or one of its resonance forms, are tagged which such a name. We discuss this issue, on the basis of the data evidencing the metal‐carbene nature of those intermediates, as well as the existence of carbenoids of type (N2)(M)CR1R2 en route to the formation to LnM=CR1R2′ from diazo reagents. We propose the exclusive use of the carbenoid term to species of type (X)(M)CR1R2 with a tetrasubstituted carbon center that upon loss of X afford an effective carbene transfer process.
Planar Polyolefin Nanostripes: Perhydrogenated Graphene
Authors: Bouša Daniel , Huber Štěphán , Sedmidubský David , Pumera Martin , Sofer Zdeněk 
Published: June 2017

AbstractGraphene hydrogenation gives an opportunity to introduce a band gap into the graphene electronic structure. Complete hydrogenation may lead to the graphane, a fully hydrogenated counterpart of graphene. However, pure graphane has not been successfully prepared to this day. Here, we show that hydrogenation of single‐walled carbon nanotubes by means of Birch reduction leads to graphene‐based carbon nanostripes with uniform dimensions. Such a material exhibits interesting electrocatalytic and magnetic properties as well huge potential for hydrogen storage since the weight concentration of hydrogen is 8.78 wt.% corresponding to the composition of C1H1.22O0.05 and thus exceeding the theoretical concentration in pure graphane (7.74 wt.%). The obtained concentration of hydrogen is the highest value ever reported for any graphene‐based material and significantly exceeds the ultimate goal of the U.S. Department of Energy for a hydrogen storage material of 7.5 wt.%.
The Air that I Breathe
Authors: Salthammer Tunga 
Published: June 2017

ZusammenfassungIn einer modernen Industriegesellschaft halten sich Menschen den größten Teil ihrer Zeit in Innenräumen auf. Daher ist eine gute Innenraumluft eine wichtige Basis für unsere Gesundheit und unser Wohlergehen. Die chemische Zusammensetzung der Raumluft ist von einer komplexen Zusammenwirkung mehrerer Faktoren wie Raumlufttemperatur, Luftfeuchte, Lüftung, Quellenstärke und Lebensgewohnheiten, abhängig. Die zuverlässige Beurteilung der menschlichen Exposition mit den gasförmigen und partikulären Raumluftkomponenten verlangt das detaillierte Verständnis von physikalischen und chemischen Stoffeigenschaften, ihrer Dynamik, Interaktion und chemischen Reaktionen.