bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separate Einstein‐Eddington spaces and the cosmological constant
Authors: Azri Hemza 
Published: January 2016

Based on Eddington affine variational principle on a locally product manifold, we derive the separate Einstein space described by its Ricci tensor. The derived field equations split into two field equations of motion that describe two maximally symmetric spaces with two cosmological constants. We argue that the invariance of the bi‐field equations under projections on the separate spaces, may render one of the cosmological constants to zero. We also formulate the model in the presence of a scalar field. The resulted separate Einstein‐Eddington spaces maybe considered as two states that describe the universe before and after inflation. A possibly interesting affine action for a general perfect fluid is also proposed. It turns out that the condition which leads to zero cosmological constant in the vacuum case, eliminates here the effects of the gravitational mass density of the perfect fluid, and the dynamic of the universe in its final state is governed by only the inertial mass density of the fluid.
image
Elektrisch leitfähige poröse Metall‐organische Gerüstverbindungen
Authors: Sun Lei , Campbell Michael G. , Dincă Mircea 
Published: January 2016

AbstractAufgrund ihrer strukturellen, chemischen und funktionellen Vielfalt werden Metall‐organische Gerüstverbindungen (MOFs) seit etwa zwei Jahrzehnten für energierelevante Anwendungen erforscht. Bis vor kurzem mangelte es dabei aber an Anwendungen, für die ein guter Ladungstransport zusammen mit Porosität und einer großen Oberfläche erforderlich ist. Die meisten MOFs sind elektrische Isolatoren, und erst unlängst wurde für einige Materialien dieser Klasse ausgezeichnete elektrische Leitfähigkeit und hohe Ladungsmobilität gefunden. In diesem Aufsatz geben wir eine Übersicht über synthetische und elektronische Designstrategien für Gerüste mit permanenter Porosität und Ladungstransport über große Distanzen. Ferner diskutieren wir wegweisende Experimente zum elektrischen Ladungstransport und ausgewählte Anwendungen für diese spezielle Unterklasse von MOFs.
Hypercrosslinked Additives for Ageless Gas‐Separation Membranes
Authors: Lau Cher Hon , Mulet Xavier , Konstas Kristina , Doherty Cara M. , Sani Marc‐Antoine , Separovic Frances , Hill Matthew R. , Wood Colin D. 
Published: January 2016

AbstractThe loss of internal pores, a process known as physical aging, inhibits the long‐term use of the most promising gas‐separation polymers. Previously we reported that a porous aromatic framework (PAF‐1) could form a remarkable nanocomposite with gas‐separation polymers to stop aging. However, PAF‐1 synthesis is very onerous both from a reagent and reaction‐condition perspective, making it difficult to scale‐up. We now reveal a highly dispersible and scalable additive based on α,α′‐dichloro‐p‐xylene (p‐DCX), that inhibits aging more effectively, and crucially almost doubles gas‐transport selectivity. These synergistic effects are related to the intimately mixed nanocomposite that is formed though the high dispersibility of p‐DCX in the gas‐separation polymer. This reduces particle‐size effects and the internal free volume is almost unchanged over time. This study shows this inexpensive and scalable polymer additive delivers exceptional gas‐transport performance and selectivity.
Mesoporous Manganese Oxide Catalyzed Aerobic Oxidative Coupling of Anilines To Aromatic Azo Compounds
Authors: Dutta Biswanath , Biswas Sourav , Sharma Vinit , Savage Nancy Ortins , Alpay S. Pamir , Suib Steven L. 
Published: January 2016

AbstractHerein we introduce an environmentally friendly approach to the synthesis of symmetrical and asymmetrical aromatic azo compounds by using air as the sole oxidant under mild reaction conditions in the presence of cost‐effective and reusable mesoporous manganese oxide materials.
iBodies: Modular Synthetic Antibody Mimetics Based on Hydrophilic Polymers Decorated with Functional Moieties
Authors: Šácha Pavel , Knedlík Tomáš , Schimer Jiří , Tykvart Jan , Parolek Jan , Navrátil Václav , Dvořáková Petra , Sedlák František , Ulbrich Karel , Strohalm Jiří , Majer Pavel , Šubr Vladimír , Konvalinka Jan 
Published: January 2016

AbstractAntibodies are indispensable tools for biomedicine and anticancer therapy. Nevertheless, their use is compromised by high production costs, limited stability, and difficulty of chemical modification. The design and preparation of synthetic polymer conjugates capable of replacing antibodies in biomedical applications such as ELISA, flow cytometry, immunocytochemistry, and immunoprecipitation is reported. The conjugates, named “iBodies”, consist of an HPMA copolymer decorated with low‐molecular‐weight compounds that function as targeting ligands, affinity anchors, and imaging probes. We prepared specific conjugates targeting several proteins with known ligands and used these iBodies for enzyme inhibition, protein isolation, immobilization, quantification, and live‐cell imaging. Our data indicate that this highly modular and versatile polymer system can be used to produce inexpensive and stable antibody substitutes directed toward virtually any protein of interest with a known ligand.
Dimerization of Organic Dyes on Luminescent Gold Nanoparticles for Ratiometric pH Sensing
Authors: Sun Shasha , Ning Xuhui , Zhang Greg , Wang Yen‐Chung , Peng Chuanqi , Zheng Jie 
Published: January 2016

AbstractSynergistic effects arising from the conjugation of organic dyes onto non‐luminescent metal nanoparticles (NPs) have greatly broadened their applications in both imaging and sensing. Herein, we report that conjugation of a well‐known pH‐insensitive dye, tetramethyl‐rhodamine (TAMRA), to pH‐insensitive luminescent gold nanoparticles (AuNPs) can lead to an ultrasmall nanoindicator that can fluorescently report local pH in a ratiometric way. Such synergy originated from the dimerization of TAMRA on AuNPs, of which geometry was very sensitive to surface charges of the AuNPs and can be reversely modulated through protonation of surrounding glutathione ligands. Not limited to pH‐insensitive dyes, this pH‐dependent dimerization can also enhance the pH sensitivity of fluorescein, a well‐known pH‐sensitive dye, within a larger pH range, opening up a new pathway to design ultrasmall fluorescent ratiometric nanoindicators with tunable wavelengths and pH response ranges.
Expedient Synthesis of (+)‐Lycopalhine A
Authors: Williams Benjamin M. , Trauner Dirk 
Published: January 2016

AbstractTwo amino acids play a key role in the first total synthesis of lycopalhine A. l‐glutamic acid serves as a convenient chiral starting material for the 13‐step synthesis, and l‐proline promotes an unusual 5‐endo‐trig Mannich cyclization that generates the central pyrrolidine ring of the Lycopodium alkaloid. The bicyclo[3.3.0]octanol moiety of the molecule is formed through an intramolecular aldol addition that may occur spontaneously in nature.
Recognition and Sensing of Creatinine
Authors: Guinovart Tomàs , Hernández‐Alonso Daniel , Adriaenssens Louis , Blondeau Pascal , Martínez‐Belmonte Marta , Rius F. Xavier , Andrade Francisco J. , Ballester Pablo 
Published: January 2016

AbstractCurrent methods for creatinine quantification suffer from significant drawbacks when aiming to combine accuracy, simplicity, and affordability. Here, an unprecedented synthetic receptor, an aryl‐substituted calix[4]pyrrole with a monophosphonate bridge, is reported that displays remarkable affinity for creatinine and the creatininium cation. The receptor works by including the guest in its deep and polar aromatic cavity and establishing directional interactions in three dimensions. When incorporated into a suitable polymeric membrane, this molecule acts as an ionophore. A highly sensitive and selective potentiometric sensor suitable for the determination of creatinine levels in biological fluids, such as urine or plasma, in an accurate, fast, simple, and cost‐effective way has thus been developed.
A Potent Glucose–Platinum Conjugate Exploits Glucose Transporters and Preferentially Accumulates in Cancer Cells
Authors: Patra Malay , Johnstone Timothy C. , Suntharalingam Kogularamanan , Lippard Stephen J. 
Published: January 2016

AbstractThree rationally designed glucose–platinum conjugates (Glc–Pts) were synthesized and their biological activities evaluated. The Glc–Pts, 1–3, exhibit high levels of cytotoxicity toward a panel of cancer cells. The subcellular target and cellular uptake mechanism of the Glc–Pts were elucidated. For uptake into cells, Glc–Pt 1 exploits both glucose and organic cation transporters, both widely overexpressed in cancer. Compound 1 preferentially accumulates in and annihilates cancer, compared to normal epithelial, cells in vitro.
Expanding the Landscape of Diterpene Structural Diversity through Stereochemically Controlled Combinatorial Biosynthesis
Authors: Andersen‐Ranberg Johan , Kongstad Kenneth Thermann , Nielsen Morten Thrane , Jensen Niels Bjerg , Pateraki Irini , Bach Søren Spanner , Hamberger Britta , Zerbe Philipp , Staerk Dan , Bohlmann Jörg , Møller Birger Lindberg , Hamberger Björn 
Published: January 2016

AbstractPlant‐derived diterpenoids serve as important pharmaceuticals, food additives, and fragrances, yet their low natural abundance and high structural complexity limits their broader industrial utilization. By mimicking the modularity of diterpene biosynthesis in plants, we constructed 51 functional combinations of class I and II diterpene synthases, 41 of which are “new‐to‐nature”. Stereoselective biosynthesis of over 50 diterpene skeletons was demonstrated, including natural variants and novel enantiomeric or diastereomeric counterparts. Scalable biotechnological production for four industrially relevant targets was accomplished in engineered strains of Saccharomyces cerevisiae.
Assembly of an Axially Chiral Dynamic Redox System with a Perfluorobiphenyl Skeleton into Dumbbell‐ or Tripod‐type Electron Donors
Authors: Tamaoki Hitomi , Katoono Ryo , Fujiwara Kenshu , Suzuki Takanori 
Published: January 2016

AbstractThe incorporation of F atoms endows a diethenylbiphenyl‐based electron donor with configurational stability and SNAr reactivity. The former enables the dynamic redox pair of (Rax)‐1/(Rax,R,R)‐12+ to exhibit drastic UV/Vis and CD spectral changes upon electrolysis, whereas the latter makes it possible for (Rax)‐1 to serve as a useful chiral synthon for the production of larger assemblies [(Rax,Rax)‐2 d,p,m and (Rax,Rax,Rax)‐3] containing two or three dyrex units. These dyads and triad also exhibit a clean electrochiroptical response with isosbestic points owing to one‐wave multi‐electron transfer.
Metal‐Free Synthesis of Fluorinated Indoles Enabled by Oxidative Dearomatization
Authors: Vitaku Edon , Smith David T. , Njardarson Jon T. 
Published: January 2016

AbstractNitrogen heterocycles are found in a majority of approved small‐molecule pharmaceuticals, and the number of approved fluorinated drugs is increasing each decade. Therefore, new approaches for accessing fluorinated nitrogen heterocycles are of great significance. A novel, scalable, and metal‐free method for accessing a wide range of fluorinated indoles is described. This oxidative‐dearomatization‐enabled approach assembles 2‐trifluoromethyl NH‐indole products from simple commercially available anilines with hexafluoroacetylacetone in the presence of an organic oxidant. The nature of the aniline N‐capping group is critical for the success of this new reaction. Furthermore, the indole products contain a 3‐trifluoroacetyl group, which can be exploited to access a plethora of useful functional groups.
Electrically Conductive Porous Metal–Organic Frameworks
Authors: Sun Lei , Campbell Michael G. , Dincă Mircea 
Published: January 2016

AbstractOwing to their outstanding structural, chemical, and functional diversity, metal–organic frameworks (MOFs) have attracted considerable attention over the last two decades in a variety of energy‐related applications. Notably missing among these, until recently, were applications that required good charge transport coexisting with porosity and high surface area. Although most MOFs are electrical insulators, several materials in this class have recently demonstrated excellent electrical conductivity and high charge mobility. Herein we review the synthetic and electronic design strategies that have been employed thus far for producing frameworks with permanent porosity and long‐range charge transport properties. In addition, key experiments that have been employed to demonstrate electrical transport, as well as selected applications for this subclass of MOFs, will be discussed.
Structure‐Based Development of an Affinity Probe for Sirtuin 2
Authors: Schiedel Matthias , Rumpf Tobias , Karaman Berin , Lehotzky Attila , Gerhardt Stefan , Ovádi Judit , Sippl Wolfgang , Einsle Oliver , Jung Manfred 
Published: January 2016

AbstractSirtuins are NAD+‐dependent protein deacylases that cleave off acetyl groups, as well as other acyl groups, from the ɛ‐amino group of lysines in histones and other substrate proteins. Dysregulation of human Sirt2 activity has been associated with the pathogenesis of cancer, inflammation, and neurodegeneration, thus making Sirt2 a promising target for pharmaceutical intervention. Here, based on a crystal structure of Sirt2 in complex with an optimized sirtuin rearranging ligand (SirReal) that shows improved potency, water solubility, and cellular efficacy, we present the development of the first Sirt2‐selective affinity probe. A slow dissociation of the probe/enzyme complex offers new applications for SirReals, such as biophysical characterization, fragment‐based screening, and affinity pull‐down assays. This possibility makes the SirReal probe an important tool for studying sirtuin biology.
Numerical and experimental investigations on the physical characteristics of supersonic steam jet induced hydrodynamic instabilities
Authors: Khan Afrasyab , Sanaullah Khairuddin , Takriff M. Sobri , Zen Hushairi , Rigit Andrew Ragai Henry , Shah Ajmal , Chughtai Imran Rafiq 
Published: January 2016

AbstractHydrodynamic instabilities play a silent lethal role for the systems involving steam as one of its working fluid. They reduce the fatigue life of the pipes by exerting stresses at their walls. These instabilities created at the interface between steam and water and propagated towards the walls of the confinement. In the current research, three physical characteristics of these hydrodynamic instabilities have been discussed using Computational Fluid Dynamic (CFD) as well as experimental approaches. These characteristics include their spatial prevalence on the length scale, amplitude, and the number of their occurrences. All of these characteristics have been predicted at specific hydrodynamic conditions in terms of temperature fluctuations. It has been observed that these characteristics are exhibited by the hydrodynamic instabilities in a random and non‐deterministic manner. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Investigation of the effects of perlite additive on some comfort and acoustical properties of polyester fabrics
Authors: Karaca Esra , Omeroglu Sunay , Akcam Okan 
Published: January 2016

ABSTRACTNatural perlite material was added for the first time into a polyester filament yarn structure. The water absorption and heat and sound insulation properties of the fabrics produced from textured and twisted polyester yarns containing 1.25% perlite additive were tested, and the results were compared with those obtained on the fabrics produced from reference polyester yarns. Although there are differences between the mechanical properties of the polyester yarns, the yarns including perlite remained within commercial usage limits. The thermal resistance values of polyester sateen fabrics obtained from perlite‐containing yarns were higher than those of the reference fabrics. The contribution of perlite led to a marked improvement, especially in the hydrophilicity and sound insulation of the polyester fabrics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43128.
POEGMA‐b‐PAA comb‐like polymer dispersant for Al2 suspensions
Authors: Wang Anqi , Qiao Min , Xu Jian , Pan Yumei , Ran Qianping , Wu Shishan , Chen Qiang 
Published: January 2016

ABSTRACTPOEGMA‐b‐PAA comb‐like polymer is synthesized through RAFT polymerization, and it is employed as an efficient dispersant for Al2O3 suspensions. The POEGMA‐b‐PAA polymer consists of PAA chains and POEGMA comb‐like chains. The former provide electrostatic attraction between Al2O3 particles and polymer, while the latter extend to solution and maintain the stability of suspension due to strong steric hindrance. The adsorption is proven and the rheology behaviors of Al2O3 suspensions are strongly improved. Different POEGMA‐b‐PAA polymers with different length of side chains have similar but not identical rheological properties. The polymer with the appropriate length of side chain provides the biggest improvement to rheological properties of Al2O3 suspensions, such as apparent viscosity and granularity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43352.
Preparation of PTFE/graphene nanocomposites by compression moulding and free sintering: A guideline
Authors: van Rooyen Louis Johann , Bissett Hertzog , Khoathane Moshibudi Caroline , Karger‐Kocsis Jozsef 
Published: January 2016

ABSTRACTThis work was aimed at preparing polytetrafluoroethylene (PTFE) nanocomposites filled with graphene nanoplatelets and investigating how the graphene nanoplatelets and the preparation techniques influenced the physical properties. Graphene was incorporated up to 4 vol % of the total PTFE system by dry and solvent assisted blending. The powder compaction was evaluated using the Kawakita/Ludde model to describe the compressibility of the powder blends. The nanocomposite billets were prepared using cold compression moulding by applying preform pressures between 12.7 and 140 MPa and the preform billets were sintered at 380°C using a specific sintering cycle. The changes in the physical dimensions, billet mass, density, and void content of the billets, pre and post sintering, were analyzed with experimental design to evaluate the influence of the precompaction pressure and graphene loading. From the evaluation it was concluded that the ideal compaction pressure was at 12.7 MPa and the solvent assisted blending was superior to the mechanical blending method. Furthermore, the compression creep tests confirmed the ideal processing temperature and graphene loading range to improve the mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43369.
Increased Conformational Flexibility of HLA–B*27 Subtypes Associated With Ankylosing Spondylitis
Authors: Loll Bernhard , Fabian Heinz , Huser Hans , Hee Chee‐Seng , Ziegler Alexander , Uchanska‐Ziegler Barbara , Ziegler Andreas 
Published: January 2016

ObjectiveDissimilarities in antigen processing and presentation are known to contribute to the differential association of HLA–B*27 subtypes with the inflammatory rheumatic disease ankylosing spondylitis (AS). In support of this notion, previous x‐ray crystallographic data showed that peptides can be displayed by almost identical HLA–B*27 molecules in a subtype‐dependent manner, allowing cytotoxic T lymphocytes to distinguish between these subtypes. For example, a human self‐peptide derived from vasoactive intestinal peptide receptor type 1 (pVIPR; sequence RRKWRRWHL) is displayed in a single conformation by B*27:09 (which is not associated with AS), while B*27:05 (which is associated with AS) presents the peptide in a dual binding mode. In addition, differences in conformational flexibility between these subtypes might affect their stability or antigen presentation capability. This study was undertaken to investigate B*27:04 and B*27:06, another pair of minimally distinct HLA–B*27 subtypes, to assess whether dual peptide conformations or structural dynamics play a role in the initiation of AS.MethodsUsing x‐ray crystallography, we determined the structures of the pVIPR–B*27:04 and pVIPR–B*27:06 complexes and used isotope‐edited infrared (IR) spectroscopy to probe the dynamics of these HLA–B*27 subtypes.ResultsAs opposed to B*27:05 and B*27:09, B*27:04 (which is associated with AS) displays pVIPR conventionally and B*27:06 (which is not associated with AS) presents the peptide in a dual conformation. Comparison of the 4 HLA–B*27 subtypes using IR spectroscopy revealed that B*27:04 and B*27:05 possess elevated molecular dynamics compared to the nonassociated subtypes B*27:06 and B*27:09.ConclusionOur results demonstrate that an increase in conformational flexibility characterizes the disease‐associated subtypes B*27:04 and B*27:05.
Association of Systemic Sclerosis With a Unique Colonic Microbial Consortium
Authors: Volkmann Elizabeth R. , Chang Yu‐Ling , Barroso Nashla , Furst Daniel E. , Clements Philip J. , Gorn Alan H. , Roth Bennett E. , Conklin Jeffrey L. , Getzug Terri , Borneman James , McGovern Dermot P. B. , Tong Maomeng , Jacobs Jonathan P. , Braun Jonathan 
Published: January 2016

ObjectiveTo compare colonic microbial composition in systemic sclerosis (SSc) patients and healthy controls and to determine whether certain microbial genera are associated with gastrointestinal (GI) tract symptoms in patients with SSc.MethodsHealthy controls were age‐ and sex‐matched (1:1) with adult SSc patients. Cecum and sigmoid mucosal lavage samples were obtained during colonoscopy. The microbiota in these samples were determined by Illumina HiSeq 2000 16S sequencing, and operational taxonomic units were selected. Linear discriminant analysis effect size was used to identify the genera that showed differential expression in SSc patients versus controls. Differential expression analysis for sequence count data was used to identify specific genera associated with GI tract symptoms.ResultsAmong 17 patients with SSc (88% female; median age 52.1 years), the mean ± SD total GI Tract 2.0 score was 0.7 ± 0.6. Principal coordinate analysis illustrated significant differences in microbial communities in the cecum and sigmoid regions in SSc patients versus healthy controls (both P = 0.001). Similar to the findings in inflammatory disease states, SSc patients had decreased levels of commensal bacteria, such as Faecalibacterium and Clostridium, and increased levels of pathobiont bacteria, such as Fusobacterium and γ‐Proteobacteria, compared with healthy controls. Bifidobacterium and Lactobacillus, which are typically reduced under conditions of inflammation, were also increased in abundance in patients with SSc. In SSc patients with moderate/severe GI tract symptoms, the abundance of Bacteroides fragilis was decreased, and that of Fusobacterium was increased, compared with patients who had no or mild symptoms.ConclusionThis study demonstrates a distinct colonic microbial signature in SSc patients compared with healthy controls. This unique ecologic change may perpetuate immunologic aberrations and contribute to clinical manifestations of SSc.