bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cationic Hybrid Hydrogels from Amino‐Acid‐Based Poly(ester amide): Fabrication, Characterization, and Biological Properties
Authors: Wu Jun , Wu Dequn , Mutschler Martha A. , Chu Chih‐Chang 
Published: June 2012

AbstractA family of biodegradable, biocompatible, water soluble cationic polymer precursor, arginine‐based unsaturated poly (ester amide) (Arg‐UPEA), is reported. Its incorporation into conventional Pluronic diacrylate (Pluronic‐DA) to form hybrid hydrogels for a significant improvement of the biological performance of current synthetic hydrogels is shown. The gel fraction (Gf), equilibrium swelling ratio (Qeq), compressive modulus, and interior morphology of the hybrid hydrogels as well as their interactions with human fibroblasts and bovine endothelial cells are fully investigated. It is found that the incorporation of Arg‐UPEA into Pluronic‐DA hydrogels significantly changes their Qeq, mechanical strength, and interior morphology. The structure–property relationship of the newly fabricated hybrid hydrogels is studied in terms of the chemical structure of the Arg‐UPEA precursor, i.e., the number of methylene groups in the Arg‐UPEA repeating unit. The results indicate that increasing methylene groups in the Arg‐UPEA repeating unit increases Qeq and decreases the compressive modulus of hydrogels. When compared with a pure Pluronic hydrogel, the cationic Arg‐UPEAs/Pluronic hybrid hydrogels greatly improve the attachment and proliferation of human fibroblasts on hydrogel surfaces. A bovine aortic endothelial cells (BAEC) viability test in the interior of the hydrogels shows that the positively charged hybrid hydrogels can significantly improve the viability of the encapsulated endothelial cell over a 2 week study period when compared with a pure Pluronic hydrogel.
Large AuAg Alloy Nanoparticles Synthesized in Organic Media Using a One‐Pot Reaction: Their Applications for High‐Performance Bulk Heterojunction Solar Cells
Authors: Chen Hsieh‐Chih , Chou Shang‐Wei , Tseng Wei‐Hsuan , Chen I‐Wen P. , Liu Chi‐Chang , Liu Chun , Liu Chien‐Liang , Chen Chun‐hsien , Wu Chih‐I , Chou Pi‐Tai 
Published: June 2012

AbstractA one‐pot synthesis of large size and high quality AuAg alloy nanoparticles (NPs) with well controlled compositions via hot organic media is demonstrated. Amid the synthesis, complexation between trioctylphosphine (TOP) and metal precursors is found, which slows down the rate of nucleation and leads to the growth of large‐size AuAg nanoalloys. The wavelength and relative intensities of the resulting plasmon bands are readily fine‐tuned during the synthetic process using different Au/Ag precursors molar ratios. In the polymer solar cells, a key step in achieving high efficiency is the utilization of 1% Au11Ag89 alloy NPs embedded in the active layer to promote the power conversion efficiency (PCE) up to 4.73%, which outperforms the reference device based on the control standard device of poly(3‐hexylthiophene) (P3HT):phenyl‐C61‐butyric acid methyl ester (PC61BM) under identical conditions. Corresponding increases in short‐circuit current density (Jsc), open‐circuit voltage (Voc), fill factor (FF), and incident photon‐to‐current efficiency (IPCE) enable 31% PCE improvement due to the enhancement of the light‐trapping and the improvement of charge transport in the active layer. The findings advance the fundamental understanding and point to the superiority of Au11Ag89 nanoalloys as a promising metallic additive over Au, Ag, and Au28Ag72 alloy NPs to boost the solar cell performance.
Modular Ligation of Thioamide Functional Peptides onto Solid Cellulose Substrates
Authors: Tischer Thomas , Goldmann Anja S. , Linkert Katharina , Trouillet Vanessa , Börner Hans G. , Barner‐Kowollik Christopher 
Published: June 2012

AbstractHetero Diels‐Alder (HDA) cycloaddition – as an effective modular conjugation approach – is employed to graft thioamide endfunctional oligopeptides onto solid cyclopentadienyl (Cp) functional cellulose substrates generating cellulose‐peptide hybrid materials. The highly reactive Cp moieties serve as diene functionality in the consecutive HDA reaction on the biosubstrate surface. Oligopeptides (i.e., the model peptide Gly‐Gly‐Arg‐Phe‐Pro‐Trp‐Trp‐Gly and the antimicrobial peptide tritrpticin) are functionalized at their N‐termini employing strongly electron deficient thiocarbonyl thio compounds resulting in biomacromolecules bearing a thioamide endgroup. The dienophile‐ functional peptides readily undergo HDA reactions at ambient temperature and under mild conditions in solution with synthetic polymers as well as on solid (bio)substrates. An in‐depth investigation is provided of the influence of the temperature, the Lewis acid catalysis and the side group exchange of thioamide functional oligopeptides reacting with Cp terminated poly(methyl methacrylate) (Mn = 2100 g·mol−1, PDI = 1.1) in homogenous solution as well as Cp functionalized cellulose in a heterogeneous system. To assess the success of the grafting reaction, the soluble samples were subjected to characterization methods such as size exclusion chromatography (SEC) and SEC‐electrospray ionization mass spectrometry (SEC‐ESI‐MS). The heterogeneous “grafting‐to” reactions were monitored using high resolution attenuated total reflection (ATR) Fourier transform infrared microscopy (HR‐FTIRM) imaging, X‐ray photoelectron spectroscopy (XPS) and elemental analysis. Evaluation via elemental analysis leads to quantitative peptide cellulose surface loading capacities.
Hexahistidine‐Tagged Single‐Walled Carbon Nanotubes (His6‐tagSWNTs): A Multifunctional Hard Template for Hierarchical Directed Self‐Assembly and Nanocomposite Construction
Authors: Baati Rachid , Ihiawakrim Dris , Mafouana Rodrigue R. , Ersen Ovidiu , Dietlin Céline , Duportail Guy 
Published: June 2012

AbstractWhile a hexahistidine affinity tag can be introduced at protein termini or internal sites by standard molecular biology procedures for purification, immobilization, or labeling of proteins, here the versatility of this concept is exploited for the chemical preparation of novel hexahistidine‐tagged single‐walled carbon nanotubes (His6‐tagSWNTs), a novel hard template useful for solubilizing, assembling, processing, and interfacing SWNTs in aqueous conditions. Water‐soluble and exfoliated His6‐tagSWNTs are prepared and fully characterized. This functional molecular module is able to interact via robust physisorption (π−π stacking) with the sidewall of SWNTs and combines the versatility of small, water‐soluble reporters (His6) for hierarchical directed self‐assembly (HDSA) and construction of nanocomposites. It is demonstrated that metal coordination bonds with Ni(II) can be used for the supramolecular self assembly of His6‐tagSWNTs, generating complex reticulated networks and architectures. The His6‐tagSWNTs hard template nanohybrid is further utilized for directed self‐assembly with silica nanoparticles. The versatility of the novel hybrids opens a new era for the rational design, smart (bio)functionalization, processing, interfacing, and self assembling of carbon nanotubes for the construction of multicomposites and more complex systems with controllable spatial organization and programmable properties for a wide range of applications in biology, nanoelectronics, and catalysis.
High Efficiency Semiconductor‐Liquid Junction Solar Cells based on Cu/Cu2O
Authors: Shao Fang , Sun Jing , Gao Lian , Luo Jianqiang , Liu Yangqiao , Yang Songwang 
Published: June 2012

AbstractCu/Cu2O photoelectrodes are synthesized by a simple electrodepositing process at low temperature. The values of the electrolyte pH have great influence on the morphology and the compositions of the obtained films, and thus affect the performance of the electrodes. The best device based on Cu/Cu2O and I−/I3− electrolyte gives a high conversion efficiency of 3.13% under simulated AM1.5G illumination. To the best of our knowledge, this is the highest efficiency reported for solar cells based on electrodeposited Cu2O. For comparison purposes, pure Cu2O films are also synthesized. The performance of the solar cells based on pure Cu2O is very poor, as low as 0.013%. In addition, the Cu/Cu2O films are perfectly compatible with the lightweight plastic substrates and yielded a power conversion efficiency of 1.44%.
Electrogenerated Chemiluminescence from a Phenyleneethynylene Derivative and its Ultrasensitive Immunosensing Application Using a Nanotubular Mesoporous Pt–Ag Alloy for Signal Amplification
Authors: Yan Mei , Ge Lei , Gao Weiqiang , Yu Jinghua , Song Xianrang , Ge Shenguang , Jia Zhiyong , Chu Chengchao 
Published: June 2012

AbstractElectrogenerated chemiluminescence (ECL) of a novel phenyleneethynylene derivatives [4,4’‐(2,5‐dimethoxy‐1,4‐phenylene)bis(ethyne‐2,1‐diyl) dibenzoic acid; P‐acid] possessing carboxylic acid groups at the para positions in aqueous solutions and its first immunosensing application are studied. Nanotubular mesoporous Pt–Ag alloy nanoparticles are first used to fabricate the ECL immunosensor as a signal amplification carrier. Absorption, photoluminescence, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy are used as powerful tools to characterize P‐acid, Pt–Ag alloy nanoparticles, and the fabrication process of the immunosensor. P‐acid exhibits two ECL peaks at –1.07 (ECL‐1) and 0.64 (ECL‐2) V in air‐saturated pH 7.4, 0.1 M PBS containing 0.1 M KCl during the cyclic sweep between 1.51 and –2.67 V at 0.1 V s−1; the ECL mechanism of these two ECL peaks is demonstrated. The electron‐transfer reaction between electrochemically oxidized P‐acid and tri‐n‐propylamine (TPrA) radical cation is also demonstrated to produce high ECL emissions and used to develop an ultrasensitive ECL immunosensor. In addition, a Pt–Ag alloy nanoparticles amplification carrier for protein ECL analysis is applied for improvement of the detection sensitivity. Thus, this ECL immunosensor exhibits high sensitivity, good reproducibility, rapid response, and long‐term stability.
Materials Science and Materials Chemistry for Large Scale Electrochemical Energy Storage: From Transportation to Electrical Grid
Authors: Liu Jun , Zhang Ji‐Guang , Yang Zhenguo , Lemmon John P. , Imhoff Carl , Graff Gordon L. , Li Liyu , Hu Jianzhi , Wang Chongmin , Xiao Jie , Xia Gordon , Viswanathan Vilayanur V. , Baskaran Suresh , Sprenkle Vincent , Li Xiaolin , Shao Yuyan , Schwenzer Birgit 
Published: June 2012

AbstractLarge‐scale electrical energy storage has become more important than ever for reducing fossil energy consumption in transportation and for the widespread deployment of intermittent renewable energy in electric grid. However, significant challenges exist for its applications. Here, the status and challenges are reviewed from the perspective of materials science and materials chemistry in electrochemical energy storage technologies, such as Li‐ion batteries, sodium (sulfur and metal halide) batteries, Pb‐acid battery, redox flow batteries, and supercapacitors. Perspectives and approaches are introduced for emerging battery designs and new chemistry combinations to reduce the cost of energy storage devices.
Silk Fibroin in Tissue Engineering
Authors: Kasoju Naresh , Bora Utpal 
Published: June 2012

AbstractTissue engineering (TE) is a multidisciplinary field that aims at the in vitro engineering of tissues and organs by integrating science and technology of cells, materials and biochemical factors. Mimicking the natural extracellular matrix is one of the critical and challenging technological barriers, for which scaffold engineering has become a prime focus of research within the field of TE. Amongst the variety of materials tested, silk fibroin (SF) is increasingly being recognized as a promising material for scaffold fabrication. Ease of processing, excellent biocompatibility, remarkable mechanical properties and tailorable degradability of SF has been explored for fabrication of various articles such as films, porous matrices, hydrogels, nonwoven mats, etc., and has been investigated for use in various TE applications, including bone, tendon, ligament, cartilage, skin, liver, trachea, nerve, cornea, eardrum, dental, bladder, etc. The current review extensively covers the progress made in the SF‐based in vitro engineering and regeneration of various human tissues and identifies opportunities for further development of this field.
Li‐Redox Flow Batteries Based on Hybrid Electrolytes: At the Cross Road between Li‐ion and Redox Flow Batteries
Authors: Wang Yarong , He Ping , Zhou Haoshen 
Published: June 2012

AbstractBy moving beyond the classical intercalation chemistry and the conventional redox flow batteries, a variety of new approaches toward high energy density storage are under intensive development. Among them, Li‐redox flow batteries stand out as one that combines the existing knowledge of Li‐ion batteries with the advantage of redox flow systems, and steps further toward functioning as fuel cells by fueling the cell with an external chemical agent. Following a brief recount of the features of Li‐ion and redox flow battery systems, the concept of a Li‐redox flow battery, which emerged from a synergy of the two battery systems, is presented.
Market Dynamics in Food Supply Chains: The Impact of Globalization and Consolidation on Firms’ Market Power
Authors: Kaditi Eleni A. 
Published: June 2012

ABSTRACTThe author examines whether ownership and increased competitive pressure affect food retailers’ market power, analyzing whether all actors involved in the food supply chain deviate from the pricing behavior that exists under perfect competition. A method proposed by Roeger () is used to estimate monopoly and monopsony market power, relaxing the assumptions of perfect competition and constant returns to scale, and avoiding any endogeneity issues. The results obtained indicate that foreign investments and consolidation have a positive and significant impact on food processors’ and retailers’ mark‐ups. Food processors, agricultural producers, and wholesalers have lower price‐cost margins than retailers, whereas retailers exert monopsonistic power in the upstream food market as well. The results are robust for various estimation techniques and specifications.
Chirality Transfer and Memory of Chirality in Gold‐Catalyzed Reactions
Authors: Patil Nitin T. 
Published: June 2012

AbstractOver the last few years, gold‐catalyzed reactions that involved chirality transfer and memory of chirality (MOC) have emerged as a powerful tool in enantioselective synthesis. This technique has allowed for the single‐step synthesis of enantioenriched compounds from readily available starting materials. This Focus Review discusses this emerging field with an emphasis on mechanistic aspects and their applications in synthetic organic chemistry.
Centre Catholique de Formation et de Production à Léogâne (CCFPL) – République d'Haïti
Authors: Groll Franz , Wolf Klaus 
Published: June 2012

AbstractBei dem Erdbeben in Haiti im Januar 2010 kamen rund 316 000 Menschen ums Leben, weitere 310 000 Personen wurden verletzt und geschätzte 1,85 Millionen Menschen wurden obdachlos. Nach Einschätzungen der Regierung wurden ca. 250 000 Wohnungen und 30 000 Geschäfte zerstört. Der nachfolgende Bericht geht darauf ein, wie der Verein Pro Haiti e.V. das Projekt zur Unterstützung der wirtschaftlichen Entwicklung und des Wiederaufbaus in Haiti konzipierte, plante und realisierte. Nach Erläuterung der Ausgangssituation in Haiti und insbesondere in der Region westlich von Port‐au‐Prince erfolgt eine Vorstellung des Konzepts und eine Projektbeschreibung. In dem Ausbildungszentrum wird eine praxisorientierte Ausbildung von verschiedenen Handwerksberufen wie z. B. Zimmerer, Maurer, Schreiner, etc. angeboten, wobei im praktischen Teil nicht nur ausgebildet, sondern auch produziert und gebaut wird, sodass aus dem Erlös ein Großteil der Ausbildungskosten abgedeckt werden kann. Bei der Tragwerksplanung des Ausbildungszentrums wurde eine Konstruktion entworfen, die hinsichtlich des Lastfalls “Erdbeben” eine ausreichende Sicherheit gewährleistet und unter Berücksichtigung der lokalen Gegebenheiten wirtschaftlich hergestellt werden kann.Establishment of a training centre including production plant in a country destroyed by the earthquakeThru the earthquake in Haiti in January 2010 died approximately 316 000 people, further 310 000 people were injured and estimated 1.85 million people were left homeless. According to the government, about 250 000 homes and 30 000 shops were destroyed. The subsequent report describes, how the club Pro Haiti e.V. conceived, planned and realized the project to support the economic development and reconstruction in Haiti.After a statement of the situation in Haiti, particularly of the region West of Port au Prince, follows an introduction to the concept and a project description. The training centre offers a practice‐oriented education teaching different crafting professions such as e.g. carpenters, masons, cabinet makers, etc. Here, people are not only trained in the practical part, but they also produce and build, so that a large part of training costs can be covered by the proceeds. The structural engineering of the training centre was especially designed: A construction that takes into account the local circumstances and therefore can be produced economically while ensuring a sufficient security in terms of the load case “earthquake”.
Stahlbetonbauteile aus klima‐ und ressourcenschonendem Ökobeton
Authors: Proske Tilo , Hainer Stefan , Jakob Mathias , Garrecht Harald , Graubner Carl‐Alexander 
Published: June 2012

AbstractDer vorliegende Beitrag präsentiert am Institut für Massivbau der TU Darmstadt durchgeführte Forschungsarbeiten zu klima‐ und ressourcenschonenden Ökobetonen mit reduziertem Zementklinkergehalt. Es wird gezeigt, dass zur Herstellung von Betonen mit mittlerer Festigkeitsklasse (C20/25–C25/30) der Zementgehalt gegenüber konventionellen Mischungszusammensetzungen auf unter 150 kg/m3 verringert werden kann. Bei Stahlbetonbauteilen, die einem moderaten chemischen und physikalischen Angriff ausgesetzt sind (C30/37, Expositionsklasse XC4, XF1 und XA1), ist es technisch möglich, Betone mit einem Zementgehalt von weniger als 200 kg/m3 zu verwenden. Da die Mischungszusammensetzungen der entwickelten Ökobetone die normativ vorgegebenen Mindestzementgehalte (DIN 1045‐2:2008‐08) unterschreiten sowie die maximalen Wasserzementwerte überschreiten, wurden umfangreiche Untersuchungen zur Leistungsfähigkeit der Ökobetone durchgeführt. Dabei wurden alle bemessungsrelevanten mechanischen Eigenschaften und die für die Dauerhaftigkeit relevanten Materialkenngrößen der Betone ermittelt. Weiterhin wurde die Eignung der Betone für die industrielle Fertigung bei den Forschungspartnern überprüft. Abschließend wurden mit den Kooperationspartnern aus der Betonfertigteil‐ und Transportbetonindustrie die baupraktische Anwendbarkeit und die Sichtbetoneigenschaften an großformatigen Bauteilen sowie das Tragverhalten von Bauteilen aus Ökobeton analysiert.Eco‐friendly Concrete for Reinforced Concrete Structures – Technical Innovation for Sustainable BuildingsThis paper presents the results of studies at the Institut für Massivbau of the TU Darmstadt focused on the development of clinker reduced Green Concretes. The research results showed, that concrete with a cement content lower than 150 kg/m3 can be used for interior structures (C20/25–C25/30, exposure class XC1). It is also possible to use concrete for exterior structures (C30/37, exposure class XC4, XF1 and XA1) with less than 200 kg/m3 cement.The cement content of the developed concretes is below the minimum content according to DIN 1045‐2:2008‐08 and the water‐cement ratio exceeds the normative limit value. This requires extensive investigations on the performance of the Green Concretes. In the conducted test all mechanical design‐relevant parameters and a number of durability properties of the concrete were determined. The suitability of the concrete during the industrial production has been verified. Full‐scale samples were produced for the evaluation of the surface quality and the analyses of the load bearing capacity.
Sicherheitsreserven und Konservativitäten in der normgerechten Erdbebenauslegung von Stahlbetonbauwerken
Authors: Sadegh‐Azar Hamid , Hartmann Hans‐Georg , Wörndle Pierre 
Published: June 2012

AbstractDie Erdbebenauslegung von Bauwerken in Deutschland wie auch in den meisten anderen Ländern der Welt erfolgt deterministisch für ein in der jeweils geltenden Erdbebennorm definiertes Bemessungserdbeben. Das Bemessungsziel ist im Allgemeinen der Nachweis der Standsicherheit und damit der Ausschluss einer Gefährdung von Leib und Leben durch Tragwerksversagen. Hier stellt sich die Frage, was bei einem denkbaren auslegungsüberschreitenden Erdbeben oder bei größeren Nachbeben passieren kann. Die bisherige Erfahrung zeigt, dass im Allgemeinen eine Aktualisierung der Erdbebennorm zu einer Erhöhung des anzusetzenden Bemessungserdbebens führt. Ist somit für vorhandene Stahlbetonbauwerke direkt Gefahr im Verzug und ist ein Versagen der bestehenden ingenieurmäßig errichteten Strukturen unter Erdbebeneinwirkung anzunehmen? Ziel dieses Beitrags ist es, einige der in der Erdbebenauslegung von Stahlbetonbauwerken vorhandenen Auslegungsreserven zu identifizieren und anhand eines typischen steifen und eines flexiblen Stahlbetongebäudes zu quantifizieren. Es werden im Wesentlichen die Einflüsse der Erdbebenenergie, der Boden‐Bauwerk‐Wechselwirkung, der Rissbildung und des nichtlinearen Materialverhaltens bei Erdbeben untersucht.Safety margins and conservatisms in the seismic design of reinforced concrete buildingsThe seismic design of buildings in Germany and in most other countries of the world is a deterministic approach using a single code specified design earthquake. The design objective is generally to prevent loss of life by structural collapse. The question is, what will happen in case of a probable earthquake exceeding the design earthquake or in case of possible aftershocks. The past shows, that in most cases the evolution and update of seismic codes is associated with higher earthquakes to be used for design. Now, is there an imminent danger for the existing buildings designed according to a previous code? The objective of this paper is to identify and quantify some of the safety margins inherent in the seismic design of reinforced concrete buildings. In particular, the influences of earthquake energy, soil‐structure interaction and cracking and nonlinear material behavior of buildings during earthquake are investigated.