bluuebunny/crossref_metadata_2025_split huggingface dataset:
Skeletal muscle and bone marrow derived stromal cells: A comparison of tenocyte differentiation capabilities
Authors: Sassoon Adam A. , Ozasa Yasuhiro , Chikenji Takako , Sun Yu‐Long , Larson Dirk R. , Maas Mary L. , Zhao Chunfeng , Jen Jin , Amadio Peter C. 
Published: April 2012

AbstractThis study investigated the comparative ability of bone marrow and skeletal muscle derived stromal cells (BMSCs and SMSCs) to express a tenocyte phenotype, and whether this expression could be augmented by growth and differentiation factor‐5 (GDF‐5). Tissue harvest was performed on the hind limbs of seven dogs. Stromal cells were isolated via serial expansion in culture. After four passages, tenogenesis was induced using either ascorbic acid alone or in conjunction with GDF‐5. CD44, tenomodulin, collagen I, and collagen III expression levels were compared for each culture condition at 7 and 14 days following induction. Immunohistochemistry (IHC) was performed to evaluate cell morphology and production of tenomodulin and collagen I. SMSCs and BMSCs were successfully isolated in culture. Following tenocytic induction, SMSCs demonstrated an increased mean relative expression of tenomodulin, collagen I, and collagen III at 14 days. BMSCs only showed increased mean relative expression of collagen I, and collagen III at 14 days. IHC revealed positive staining for tenomodulin and collagen I at 14 days for both cell types. The morphology of skeletal muscle derived stromal cells at 14 days had an organized appearance in contrast to the haphazard arrangement of the bone marrow derived cells. GDF‐5 did not affect gene expression, cell staining, or cell morphology significantly. Stromal cells from either bone marrow or skeletal muscle can be induced to increase expression of matrix genes; however, based on expression of tenomodulin and cell culture morphology SMSCs may be a more ideal candidate for tenocytic differentiation. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1710–1718, 2012
HEAVY METALS IN CONTAMINATED SOILS OF THE RIO SITZERRI FLOODPLAIN (SARDINIA, ITALY): CHARACTERIZATION AND IMPACT ON PEDODIVERSITY
Authors: Vacca A. , Bianco M. R. , Murolo M. , Violante P. 
Published: April 2012

ABSTRACTFour representative soils located in areas of the Rio Sitzerri floodplain (Sardinia, Italy), which were flooded and covered by materials coming from the metalliferous mine of Montevecchio, were studied to define the total content and the geochemical forms of heavy metals and to discuss their impact on pedodiversity. The significance of heavy metal concentrations in the contaminated soils was assessed by the comparison with data coming from three selected reference soils representative for non‐contaminated areas. Most soils are deep or very deep and consist of a sequence resulting from different sedimentary cycles. The soils located in areas that were flooded and covered by materials coming from the Mine are characterised by the presence of buried horizons and are mainly contaminated by Zn, Ni, Pb, and Cd and, to some extent, by Cr and Cu. The sequential extractions indicated the presence of reactive forms in all the soils and for all contaminating metals, whose mobility risk is increased by the generally very strongly acid to slightly acid soil reaction values. As regards pedodiversity, the heavy metal contamination clearly influenced quantity, quality and function of the soils. The morphological diversity of pedons, the taxonomic and functional pedodiversity and the soilscape pattern were all strongly affected, causing irreparable damage to the local economy and to the environment. This study highlights the need for the planning of remediation actions focused on the correct disposal and management of the mining residues at Montevecchio and can contribute in a significant way to set future environmental regulations. Copyright © 2012 John Wiley & Sons, Ltd.
MONITORING THE IMPACT OF SURFACE ALBEDO ON A SALINE LAKE IN SW RUSSIA
Authors: Argaman E. , Keesstra S. D. , Zeiliguer A. 
Published: April 2012

ABSTRACTLake Elton is located east of the Volga River in Russia and covers an area of 155 km2. The hydrological system of the Lake and its surroundings are extremely vulnerable to climate change and human interference, but available local and regional information is sparse. Utilising climate data from 1987 to 2009 and surface albedo readings from the MODerate resolution Imaging Spectroradiometer satellite since 2000, this study analyses Lake degradation processes since 2005. Lake surface albedo analysis indicates that during the past 6 years, lake albedo has increased dramatically from average peak values of 0·14 to 0·40. In addition, air temperature has increased by 2 °C, and annual precipitation has decreased by 40 per cent. Moreover, human intervention in the area has increased environmental pressure on the Lake, causing a reduction of runoff inflow because of water capture, use of check‐dams and water‐harvesting systems. The results of the study show that, under current conditions, the Lake surface albedo is likely to remain high as compared with previous observations. The current trend implies an average 2 per cent per year increase in future annual albedo, with a maximum possible increase of 4 per cent up to a steady state of salt‐crust albedo values. Copyright © 2012 John Wiley & Sons, Ltd.
Nanomaterials for Ocular Drug Delivery
Authors: Liu Shengyan , Jones Lyndon , Gu Frank X. 
Published: April 2012

AbstractEfficient drug delivery to the eye remains a challenging task for pharmaceutical scientists. Due to the various anatomical barriers and the clearance mechanisms prevailing in the eye, conventional drug delivery systems, such as eye drop solutions, suffer from low bioavailability. More invasive methods, such as intravitreal injections and implants, cause adverse effects in the eye. Recently, an increasing number of scientists have turned to nanomaterial‐based drug delivery systems to address the challenges faced by conventional methods. This paper highlights recent applications of various nanomaterials, such as polymeric micelles, hydrogels, liposomes, niosomes, dendrimers, and cyclodextrins as ocular drug delivery systems to enhance the bioavailability of ocular therapeutic agents.magnified image
Synthesis of Luminescent Covalent–Organic Polymers for Detecting Nitroaromatic Explosives and Small Organic Molecules
Authors: Xiang Zhonghua , Cao Dapeng 
Published: April 2012

AbstractThree porous luminescent covalent‐‐organic polymers (COPs) have been synthesized through self‐polycondensation of the monomers of tris(4‐bromophenyl)amine, 1,3,5‐tris(4‐bromophenyl)benzene, and 2,4,6‐tris‐(4‐bromo‐phenyl)‐[1,3,5]triazine by using Ni‐catalyzed Yamamoto reaction. All the COP materials possess not only high Brunauer–Emmett–Teller (BET) specific surface area of about 2000 m2 g−1, high hydrothermal stability, but also graphene‐like layer texture. Interestingly, COP‐3 and COP‐4 show very fast responses and high sensitivity to the nitroaromatic explosives, and also high selectivity for tracing picric acid (PA) and 2,4,6‐trinitrotoluene (TNT) at low concentration (<1 ppm). In short, the COPs may be a new kind of material for detecting explosives and small organic molecules.
Highly Efficient Ring‐Opening Reaction of Azlactone‐Based Copolymer Platforms for the Design of Functionalized Materials
Authors: Laquièvre Aurélie , Allaway Naomi S. , Lyskawa Joël , Woisel Patrice , Lefebvre Jean‐Marc , Fournier David 
Published: April 2012

AbstractAzlactone‐based homopolymers and copolymers were successfully synthesized using the reversible addition–fragmentation chain transfer (RAFT) process. The functional monomer 2‐styryl‐4,4‐dimethylazlactone (SDA) was first homopolymerized in bulk then copolymerized with styrene, leading to (co)polymers with low polydispersity indices (PDI = 1.10–1.20). The reactive azlactone rings, located along the backbone of the copolymers were subjected to highly efficient ring‐opening reactions with functionalized primary amine derivatives incorporating a fluorescent (naphthalene) or an electrochemical (ferrocene) probes, a biological fragment (glutathione), a sugar unit (β‐cyclodextrin), or an oligomeric fluorinated moiety, leading to materials with various interesting properties.
Model Catalysts for Clarification of Active Site‐Polymer Relationship in Heterogeneous Olefin Polymerization
Authors: Taniike Toshiaki , Takahashi Shougo , Wada Toru , Tonosaki Kiwamu , Dwivedi Sumant , Terano Minoru 
Published: April 2012

AbstractModel catalysts having specially designed active species on support surfaces were employed to understand relationships between the structure/state of active sites and their catalytic performances for two classes of industrial olefin polymerization catalysts: Ziegler‐Natta and Phillips catalysts. Propylene polymerization using a TiCl3/MgCl2 model Ziegler‐Natta catalyst clarified an important role of the Ti dispersion state for the polymer stereo & chemical structures. Model Phillips catalysts having monochromate and dichromate structures on silica support imparted knowledge that dinuclear species is more responsible for the production of α‐olefin comonomer in ethylene polymerization, thus giving more branched polyethylene.
Method Development for Determination of n‐Hexane Solvent Extractable Materials in Polyethylene Using FIPA
Authors: van Rensburg Quentin , Luruli Nyambeni , Sadiku Rotimi 
Published: April 2012

AbstractHexane extractables or soluble materials in polyethylene are generally determined using gravimetric methods. These methods are slow, labour intensive and use large amounts of solvents. In this study, an attempt is made to develop a method for determining hexane extractable materials in both low and linear low density polyethylene. The GPC hybrid instrument from Viscotek that utilizes flow injection polymer analysis (FIPA) technique was used. Three samples with different physical forms (viz: pellets, powder and film) were investigated in order to determine whether physical forms had an effect on the results. The results obtained from FIPA were then compared to those obtained using the standard ASTM extraction method. The general trends of FIPA results showed reasonably good correlation to those obtained using ASTM method. Further, it was found that powder (ground pellets) and film samples analysed using FIPA give similar results while significant differences amongst the different physical forms were noticed in the results obtained using gravimetric methods. This could shorten turnaround times considerably when compared to long sample preparation times needed for gravimetric analytical methods. Further comparison of results between FIPA and the ASTM methods, yielded positive and promising data, when the average percentages of soluble materials obtained with CRYSTAF were considered.
Polymer‐Drug Encapsulation using Various PEG‐ and Polypeptide‐Based Block Copolymer Micelles
Authors: Veeren Anisha , Bhaw‐Luximon Archana 
Published: April 2012

AbstractVarious novel di‐or tri‐block copolymers with hydrophilic PEG and/or polylysine in association with hydrophobic polycaprolactone segments namely PEG‐b‐PolyLys and PEG‐b‐PolyLys‐b‐PCL, have been synthesized and characterized. Poly(Lys‐g‐Glu)‐b‐PCL has been successfully synthesized where D‐gluconolactone was grafted on the NH2 group of PolyLys. These copolymers self‐assemble in water to form micelles in the size range 165 to 365 nm and CMC from 0.1 mg/ml to 2 mg/ml. Both micelle size and CMC showed a strong dependency on the hydrophobic chain length. The encapsulation of Ketoprofen and Rifampicin in the different copolymer families was assessed and encapsulation efficiency determined using UV Spectroscopy. The % drug loaded was found to depend on the interaction between drug and copolymer system. Both drugs showed chemical conjugation with PolyLys segment and physical entrapment in the PCL hydrophobic core. Higher encapsulation efficiency was obtained with Rifampicin (17–70%).
Chemistry, Morphology, Microtomography and Activation of Natural and Carbonized Tannin Foams for Different Applications
Authors: Pizzi A. (Tony) , Celzard A. , Fierro V. , Tondi G. 
Published: April 2012

AbstractTannin based rigid foams are natural network structures obtained by polycondensations of polyflavonoid tannins and furfuryl alcohol. These foams have a wide range of characteristics. Physical tests such as water absorption, compression resistance, direct flame behaviour and measure of foam cell dimensions were carried out for each foam sample. Tannin‐based rigid foams, prepared from 95% natural material, are suggested for replacing synthetic phenol‐formaldehyde foams in various applications. For that purpose, a few physical properties were measured: resistance to fire and chemicals, absorption of various liquids, permeability, thermal conductivity and mechanical (compressive and tensile) strength. The materials were also found to present good resistance to strong acid and bases, and to solvents. Finally, slightly anisotropic mechanical properties were measured. The materials present a brittle behaviour, whether tested in compression or traction; nevertheless, their strengths, as well as their thermal conductivities, are fully comparable with those of their phenolic counterparts. Carbonisation of polyflavonoid tannin‐formaldehyde‐furfuryl alcohol rigid foams was found by MALDI‐TOF to yield a tridimensional network in which polynuclear aromatic hydrocarbon chains of high molecular weight are covalently linked to some furan resin structures surviving carbonisation. Structure conservation on carbonisation extends to furanic structures derived by the self condensation of furfuryl alcohol which are integral part of the total network. Some complex, tridimensional structures derived by the rearrangement to polyaromatic hydrocarbons of polyflavonoid tannins, constituting of aromatic benzene and furane rings and some formaldehyde‐derived methylene bridges appear to be formed.
Oligomers of Phenolic‐Type Resin Derived from the Condensation of Phenol with Benzyl Chloride
Authors: Dunga Nangamso , Jumbam Ndze Denis 
Published: April 2012

AbstractThe direct condensation of phenol with benzyl chloride in the absence of a catalyst at high temperatures produced a light‐brown viscous oil. A sample was analyzed by NMR, HPLC‐ESI mass spectrometry and MALDI‐TOF revealing that it is composed of a complex mixture of different low molecular weight oligomers of the phenolic‐type resin. While a good number of the peaks could be assigned to specific structures, not all of the peaks could be identified.
Surface‐Initiated Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization of Styrene from Laponite Clay Surfaces
Authors: Chirowodza Helen , Weber Wolfgang , Hartmann Patrice , Pasch Harald 
Published: April 2012

AbstractSurface‐initiated reversible addition fragmentation chain transfer polymerisation of styrene was conducted from the surface of Laponite clay particles. A new cationic chain transfer agent, 2‐(2‐(butylthio‐carbonothioylthio)propanoyloxy)‐N,N,N‐trimethylethanaminium iodide was synthesised and attached to the clay surface from which polymerisation was initiated. A free RAFT agent, ethyl 2‐(butylthiocarbonothioylthio)propanoate was added in solution to control the polymerisation of free polymer. The grafted and free polymer were then analysed by SEC to get insight into the polymerisation. The thermal stability of the polymer/clay nanocomposites and grafted clay particles was investigated by TGA.
Matrix‐Assisted Laser Desorption Ionization Mass Spectrometry of Synthetic Polymers
Authors: Mautjana Nare Alpheus , Pasch Harald 
Published: April 2012

AbstractMatrix‐assisted laser desorption/ionization (MALDI) mass spectrometry allows fast and efficient analysis of complex synthetic polymers which always exhibit varying degrees of polydispersity including molar mass distribution and chemical composition distribution. Most commonly used with a time‐of‐flight (TOF) mass analyzer, MALDI MS is the workhorse in polymer mass spectrometry and can be used to 1) identify homopolymers, 2) determine the endgroups of macromolecules, 3) elucidate polymerization mechanisms, 4) analyze copolymers, 5) determine molecular structures, and 6) determine absolute molar masses of oligomers. This paper gives an overview of the mentioned applications of MALDI MS in polymer analysis.
Statistical test planning for ultrasonic welding of dissimilar materials using the example of aluminum‐carbon fiber reinforced polymers (CFRP) joints
Authors: Balle F. , Eifler D. 
Published: April 2012

AbstractThis paper is focused on statistical test planning methods to increase process stability by means of reproducibility in comparison to a stepwise empirical variation of each process parameter during solid state joining as well as the significant reduction of experimental time and costs. The methodology will be presented for the specific challenges of ultrasonic welding. This pressure welding technology was investigated systematically for joining aluminum sheet metals to carbon fiber reinforced thermoplastic polymers (CFRP). In this study two aluminum wrought alloys were investigated to be welded onto CFRP with PA66 matrix. To evaluate suitable process parameters, the statistical model named “central composite design circumscribed (CCC)” was used to prove the weldability of the Al/CFRP‐joints. An important advantage of the CCC‐model is the description of the mutual dependence of the three central welding parameters: oscillation amplitude, welding force and energy in relation to the achievable mechanical properties of the joints. It allows the reduction of the number of necessary welds at a factor of seven in comparison to a conventional empirical investigation. All combinations of the welding parameters were proved in tensile shear tests. Additional microstructural analysis helped to understand the mechanical behaviour of ultrasonically welded hybrid joints in detail.
Diffusion bonding of transition structures for integral aluminium‐fibre reinforced polymer (FRP) compounds
Authors: Schimanski K. , von Hehl A. , Syassen F. 
Published: April 2012

AbstractComponents in hybrid design become more and more important in terms of their lightweight potential. In this context the demand for weight saving in aerospace leads to increasing numbers of applications of fibre composites for primary structural components. In consequence the use of FRP‐metal compounds is necessary. Within the investigations of the researcher group “Schwarz Silber” (FOR 1224) founded by the DFG (German Research Foundation) material optimised interface structures for advanced CFRP‐aluminium compounds are currently being studied. Within their work the researcher group focussed on three concepts realizing the transition structures: the usage of wires (titanium), foils (titanium) and fibres (glass fibre) as transition elements between CFRP and aluminium. For the connection of the aluminium sheet and the transition element die‐casting and laser beam welding are basically used. As a possible alternative to the both liquid phase processes a feasibility study haven been done focussing the solid state processes diffusion bonding. The experimental results show the high potential of this process in view of the transferable loads for integral transition structures.
Determination of local material properties of laser beam welded aluminium‐steel and aluminium‐titanium compounds
Authors: Barr A. , Hunkel M. , von Hehl A. 
Published: April 2012

AbstractThe combination of different metallic materials, such as aluminium and steel or aluminium and titanium, by firmly bonding via laser beam welding enables the production of customised hybrid lightweight designs with enhanced properties. Both weld geometry and local material behaviour, which are responsible for the final load characteristics of the compound, are influenced by the process parameters during welding. A novel approach of coupling process, microstructure and mechanical simulation, considering the development of weld geometry and local material conditions is intended to deliver a fast and reliable method for evaluating the quasi‐static strength of laser beam welded hybrid compounds. Besides the objective to promote a reduction of expensive welding experiments, the developed method can enhance the performance of hybrid structures as well as their lightweight potential for automotive and aircraft applications. The experimental determination of the local mechanical properties as the basis for the regarded simulation approach is an essential part of a running research project.
Ultrafine‐grained AA6014/AA5754 laminates produced by accumulative roll bonding (ARB)
Authors: Hausöl T. , Höppel H. W. , Göken M. 
Published: April 2012

AbstractLaminates with alternating AA6014 and AA5754 layers are produced by accumulative roll bonding (ARB). Depending on the number of ARB cycles the microstructure and the mechanical properties are investigated. The microstructure is characterized by scanning electron microscopy and correlated to the local mechanical properties determined by nanoindentation experiments. The overall properties are derived by tensile testing. The ultrafine‐grained microstructure and the local mechanical properties alter with the layer composition. With increasing number of ARB cycles a much higher grain refinement is achieved within the AA5754 layers than in the AA6014 layers. The hardness of the individual layers develops similarly. On the macroscopic scale it is shown that the laminates are unifying the desired properties of the materials involved: high strength by a simultaneous suppression of the Portevin‐Le Châtelier effect, typically occurring in the AA5754 alloy.
Behaviour of a quasicrystalline strengthened Al‐alloy during compression testing
Authors: Markoli B. , Bončina T. , Zupanič F. 
Published: April 2012

AbstractIn this work, an Al‐Mn‐Be‐Cu alloy was prepared by vacuum induction melting and casting. The alloy was then remelted and gravitationally cast into cylindrical metallic dies with 2 mm, 4 mm and 8 mm diameters in order to obtain the quasicrystalline phase in the aluminium‐rich matrix. The samples with height‐to‐thickness ratio of 3:1 were tested using compression test at room temperature. The deformation rate was 0.001 s–1. The main objective was to study the behaviour of the alloy during compression tests to obtain information regarding its plastic deformability and fracture. The compression behaviour of 2‐mm and 4‐mm samples was almost identical. They could be deformed to more than 0.9 true strain without fracture. In the plastic region, true stress of approximately 450 MPa was attained, and almost no hardening was observed. Such behaviour can arise from a microstructure consisting of primary icosahedral quasicrystalline particles and the matrix composed of two‐phase eutectic‐like structure composed of lamellar icosahedral phase and Al‐rich solid solution. The 8‐mm sample contained a considerable fraction of crystalline intermetallic compound and much less quasicrystalline phase, fractured at approximately 0.4 true strain, and at the same time, its true strength was approximately lower for 10% than that of 2‐mm and 4‐mm‐samples.