bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of a Fossil Sterane Biomarker in Crude Oil – an Androstane with a Modified Carbon Skeleton
Authors: Bender Matthias , Schmidtmann Marc , Rullkötter Jürgen , Summons Roger E. , Christoffers Jens 
Published: July 2013

AbstractThree constitutional isomers of androstane were prepared for comparison with three unknown fossil C19H32 organic biomarkers (“19A”, “19B”, and “19C” in elution order) in geological samples from Oman. 3β‐Methyl‐A‐nor‐androstane was prepared in six steps (8 % overall yield) from testosterone. The key steps of this sequence were an Eschenmoser fragmentation and recyclization of the A ring. A mixture of four stereoisomers of 3‐methyl‐A‐nor‐androstane (4 % overall yield) was prepared by ionic hydrogenation of the olefin after A‐ring recyclization in three steps. 17‐Methyl‐18‐nor‐androstane was synthesized in four steps as a mixture of isomers (58 % overall yield) from dihydrotestosterone with a Wagner–Meerwein shift of the 13β‐methyl group to C‐17 as the key step. Pure 17β‐ and 17α‐methyl‐18‐nor‐13α‐androstane (4 and 2 % overall yield, respectively) were obtained in three additional steps after α‐oxidation of the Wagner–Meerwein rearrangement product and subsequent reduction. The synthesis of 18‐nor‐D‐homo‐13β‐androstane (12 % yield over seven steps from dihydrotestosterone) involved oxidative cleavage of the C–C double bond in the Wagner–Meerwein rearrangement product from the previous synthesis and subsequent recyclization of the D ring followed by reduction. The relative configurations of all final products were confirmed by X‐ray crystallography. A comparison of the synthetic standards with the saturated hydrocarbon fraction of an Oman crude oil by gas chromatography (GC–MS) coinjection on three different GC columns and comparison of mass spectra revealed that unknown compound 19C is 18‐nor‐D‐homo‐13β,14α‐androstane, whereas the isomeric 3‐methyl‐A‐nor‐androstanes and 17‐methyl‐18‐nor‐androstanes elute close to 19A and 19B, respectively, but do not match the unknowns.
Thermodynamic Analysis of an Integrated SOFC, Solar ORC and Absorption Chiller for Tri‐generation Applications
Authors: Ozcan H. , Dincer I. 
Published: July 2013

AbstractThermodynamic performance assessment of an integrated tri‐generation energy system for power, heating and cooling production is conducted through energy and exergy analyses. Sustainability assessment is performed and some parametric studies are undertaken to analyze the impact of system parameters and environmental conditions on the system performance. The tri–generation system consists of (a) an internal reforming tubular type solid oxide fuel cell (IR‐SOFC), which works at ambient pressure and fueled with syngas, (b) a combustor and a air heat exchanger, (c) a heat recovery and steam generation unit (HRSG), (d) a two‐ stage Organic Rankine cycle (ORC) driven by exhaust gases of SOFC, (e) parabolic trough solar collectors (PTSC), and (f) a lithium‐bromide absorption chiller (AC) cycle driven by exhaust gases from SOFC unit. The largest irreversibility occurs at the SOFC unit due to high temperature requirement for reactions. Fuel utilization factor, recirculation ratio, dead state conditions, and solar unit parameters have influential effects on the system efficiencies. Energy and exergy efficiencies of tri‐generation unit become 85.1% and 32.62%, respectively, for optimum SOFC stack and environmental conditions. The overall system energy and exergy efficiencies are 56.25% and 15.44% higher than that of conventional SOFC systems, respectively.
Oxygen Isotope Transport Properties of Yttria‐Stabilized Zirconia (YSZ) in O2‐ and H2O‐Containing Atmospheres
Authors: Pietrowski M. J. , De Souza R. A. , Fartmann M. , ter Veen R. , Martin M. 
Published: July 2013

AbstractOxygen isotope exchange experiments, H218O/H216O (”wet” anneals) and 18O2/16O2 (”dry” anneals), were performed on single crystal samples of yttria‐stabilized zirconia (YSZ) at a temperature of T = 1073 K with subsequent determination of the oxygen isotope profiles in the solid by time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Such experiments yielded oxygen tracer diffusion coefficients (D*) and oxygen tracer surface exchange coefficients (k*), from both the polished (smooth) and unpolished (rough) sides of single crystal samples, as a function of water partial pressure pH2O and oxygen partial pressure pO2. Isothermal values of D* were found to depend on neither pO2 nor pH2O (nor surface roughness). Isothermal values of k*, in contrast, displayed a strong dependence on pO2 or pH2O; k*wet was, in addition, 2–3 orders of magnitude higher than k*dry. Surprisingly, surface roughness had little effect on k*wet, whereas rough surfaces exhibited much higher k*dry values than smooth surfaces. Data for k*wet obtained as a function of temperature at pH2O = 18 mbar show a change in activation enthalpy at T ≈ 973 K. The behavior of k* is discussed in terms of surface composition, surface area and surface reaction mechanisms.
A Social Network Approach to Peer Assessment: Improving Predictive Validity
Authors: Luria Gil , Kalish Yuval 
Published: July 2013

AbstractOur premise is that the simple measure used in peer assessment (i.e., number of peer nominations) does not capture the complexity of social information processing and therefore has limited predictive validity. Based on indicators derived from social network analysis and social information processing theories, we suggest new measures (nominations‐by‐nominees and nominations‐not‐returned) to enhance the predictive validity of peer assessment. We then compare the validity of existing measures with ours, using a longitudinal sample of 249 soldiers, divided into 18 groups. The soldiers first assessed each other on friendly behavior and instrumental contribution to the team. More than six months later, the commanders of the 132 soldiers in the unit under review provided evaluations of their performance in regard to stress, engagement, and leadership. We found that our new, complex measures predicted performance above and beyond the traditional measure. Theoretical and applied implications are discussed.
Bridging the Gap between Research and Practice in Organizational Network Analysis: A Conversation between Rob Cross and Martin Kilduff
Authors: Cross Rob , Kaše Robert , Kilduff Martin , King Zella 
Published: July 2013

AbstractThe article features a conversation between Rob Cross and Martin Kilduff about organizational network analysis in research and practice. It demonstrates the value of using social network perspectives in HRM. Drawing on the discussion about managing personal networks; managing the networks of others; the impact of social networking sites on perceptions of relationships; and ethical issues in organizational network analysis, we propose specific suggestions to bring social network perspectives closer to HRM researchers and practitioners and rebalance our attention to people and to their relationships.
Three‐dimensional self‐assembling peptide matrix enhances the formation of embryoid bodies and their neuronal differentiation
Authors: Li Qianqian , Chow King L. , Chau Ying 
Published: July 2013

AbstractWe have tailored the properties of a self‐assembling peptide (SAP) matrix to direct embryonic stem cells towards neuronal differentiation by adopting a three‐dimensional (3D) culture, matching mechanical strength with that of neural tissue, and incorporating fixed laminin‐derived pentapeptide signals (IKVAV). We report here that such a matrix alone can induce mouse embryonic stem (ES) cells to first develop into embryoid body (EB) and increase their propensity for subsequent neuronal differentiation. Embryoid bodies were observed by day 5 of culture in SAP matrix. βIII‐tubulin as an early neuronal commitment marker was more prominently detected in cells cultured in the matrix containing IKVAV signals. Interestingly, ES‐derived cells did not display distinct neuron morphology within the 3D culture; however, 55 ± 10% of those cells within IKVAV conjugated matrix and 38 ± 6% of those within base matrix displayed higher potential towards neuronal differentiation after 7 days. When retrieved and recultured on a tissue culture plate, they exhibited extended neurite outgrowths and networks in the absence of any additional neuronal differentiation growth factor. The up‐regulated expression of neuronal development markers (MAP2 and MeCP2) and the down‐regulation of glial marker (GFAP) support that further neuronal differentiation takes place upon reculture. The results showed that an artificial matrix composed of designer SAPs could prompt the formation of EB and provides the cues favoring neuronal differentiation of ES cells. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1991–2000, 2014.
Tissue response to composite hydrogels for vertical bone augmentation in the rat
Authors: Kinard Lucas A. , Dahlin Rebecca L. , Henslee Allan M. , Spicer Patrick P. , Chu Chia‐Ye , Tabata Yasuhiko , van den Beucken Jeroen J.J.P. , Jansen John A. , Young Simon , Wong Mark E. , Kasper F. Kurtis , Mikos Antonios G. 
Published: July 2013

AbstractThe objective of the present study was to develop a preclinical animal model for evaluating bone augmentation and to examine the level of bone augmentation induced by hydrogel composites. Design criteria outlined for the development of the animal model included rigid immobilization of bilateral implants apposed to the parietal bone of the rat, while avoiding the calvarial sutures. The animal model was evaluated through the implantation of hydrogel composites of oligo(poly(ethylene glycol) fumarate) (OPF) and gelatin microparticles releasing bone morphogenetic protein‐2 (BMP‐2). The BMP‐2 release profile was varied and compared to the implantation of a material control without BMP‐2. Each hydrogel composite was implanted within a polypropylene cassette, which was immobilized to the calvarial bone using screws, and empty cassettes were implanted as a control. The design criteria for the animal model were realized; however, the level of bone augmentation did not vary between any of the groups after 4 weeks. Osteoclastic bone resorption occurred to a higher extent in groups releasing BMP‐2, but the cause could not be elucidated. In conclusion, a promising bone augmentation model was established in the rat; however, refinement of the hydrogel composites was suggested to optimize the constructs for bone augmentation applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2079–2088, 2014.
Uniaxial cyclic strain stimulates cell proliferation and secretion of interleukin‐6 and vascular endothelial growth factor of human dermal fibroblasts seeded on chitosan scaffolds
Authors: Park Ki‐Sook , Lee Eun‐Gyu , Son Youngsook 
Published: July 2013

AbstractHuman dermal fibroblasts were inoculated into chitosan sponge scaffolds coated with type I collagen and it might be developed as a dermal substitute and/or dressing material. The application of 14% uniaxial cyclic strain to the cellular scaffolds affected the characteristics of the seeded human dermal fibroblasts. Cyclic strain enhanced cellular proliferation, the activity of metalloproteinase‐2, and the expression of extracellular matrix proteins such as fibronectin. Moreover, cyclic strain increased the expression of vascular endothelial growth factor (VEGF) and interleukin (IL)−6, which are critical to wound healing. Even under static culture (strain, 0%) following 14% cyclic strain, the expression of VEGF and IL‐6, which had increased under 14% strain, was amplified or maintained for at least 3 days. Uniaxial cyclic strain may enhance the wound‐healing potential of human dermal fibroblasts seeded on chitosan scaffolds through the changes in the cellular characteristics of the fibroblasts when the cellular scaffold is transplanted into skin wounds, especially chronic wounds such as diabetic wounds. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2268–2276, 2014.
Improved brain delivery of vincristine using dextran sulfate complex solid lipid nanoparticles: Optimization and in vivo evaluation
Authors: Aboutaleb Ehsan , Atyabi Fatemeh , Khoshayand Mohammad Reza , Vatanara Ali Reza , Ostad Seyed Nasser , Kobarfard Farzad , Dinarvand Rassoul 
Published: July 2013

AbstractVincristine (VC) sulfate, a freely water‐soluble cytotoxic agent was incorporated into cetyl palmitate solid lipid nanoparticles (SLNs) with the aid of dextran sodium sulfate (DS), a poly anion, using a microemulsion method. The manufacturing process was optimized using response surface methodology (Box–Behnken design). SLNs were characterized for size, zeta potential, morphology, crystallinity, and release behavior. The drug encapsulation efficiency reached up to 93% and release study revealed sustained drug release. SLN formulation showed comparable cytotoxic effect in comparison to VC sulfate solution against the MDA‐MB‐231 cells. The in vivo studies following injection to rat revealed higher plasma and tissue concentrations and longer drug mean residence times compared to VC solution. Using cumarin‐6 as a model drug, it was shown that drug delivery to the brain was enhanced close to five times using SLNs prepared in this study compared to free cumarin‐6. It can be concluded that complexes of cetyl palmitate SLNs with DS could produce high VC‐loaded SLNs suitable for delivery of anticancer drugs to brain tumors. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2125–2136, 2014.
Effect of doping in carbon nanotubes on the viability of biomimetic chitosan‐carbon nanotubes‐hydroxyapatite scaffolds
Authors: Fonseca‐García Abril , Mota‐Morales Josué D. , Quintero‐Ortega Iraís A. , García‐Carvajal Zaira Y. , Martínez‐López V. , Ruvalcaba Erika , Landa‐Solís Carlos , Solis Lilia , Ibarra Clemente , Gutiérrez María C. , Terrones Mauricio , Sanchez Isaac C. , del Monte Francisco , Velasquillo María C. , Luna‐Bárcenas G. 
Published: July 2013

AbstractThis work describes the preparation and characterization of biomimetic chitosan/multiwall carbon nanotubes/nano‐hydroxyapatite (CTS/MWCNT/nHAp) scaffolds and their viability for bone tissue engineering applications. The cryogenic process ice segregation‐induced self‐assembly (ISISA) was used to fabricate 3D biomimetic CTS scaffolds. Proper combination of cryogenics, freeze‐drying, nature and molecular ratio of solutes give rise to 3D porous interconnected scaffolds with clusters of nHAp distributed along the scaffold surface. The effect of doping in CNT (e.g. with oxygen and nitrogen atoms) on cell viability was tested. Under the same processing conditions, pore size was in the range of 20–150 μm and irrespective on the type of CNT. Studies on cell viability with scaffolds were carried out using human cells from periosteum biopsy. Prior to cell seeding, the immunophenotype of mesenchymal periosteum or periosteum‐derived stem cells (MSCs‐PCs) was characterized by flow cytometric analysis using fluorescence‐activated and characteristic cell surface markers for MSCs‐PCs. The characterized MSCs‐PCs maintained their periosteal potential in cell cultures until the 2nd passage from primary cell culture. Thus, the biomimetic CTS/MWCNT/nHAp scaffolds demonstrated good biocompatibility and cell viability in all cases such that it can be considered as promising biomaterials for bone tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3341–3351, 2014.
Formation of thermo‐sensitive polyelectrolyte complex micelles from two biocompatible graft copolymers for drug delivery
Authors: Li Guiying , Meng Yanfeng , Guo Lei , Zhang Ting , Liu Junshen 
Published: July 2013

AbstractThermo‐sensitive polyelectrolyte complex (PEC) micelles assembled from two biocompatible graft copolymers chitosan‐g‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAM) and carboxymethyl cellulose‐g‐poly(N‐isopropylacrylamide) (CMC‐g‐PNIPAM) were prepared for delivery of 5‐fluorouracil (5‐FU). The PEC micelles showed a narrow size distribution with core‐shell structure, in which the core formed from positively charged CS and negatively charged CMC by electrostatic interactions and the shell formed from thermo‐sensitive PNIPAM. The synthesized PEC micelles have lower critical solution temperatures (LCST) in the region of 37°C, which is favorable for smart drug delivery applications. The hydrogen bondings between PEC micelles and 5‐FU increased the drug loading. Changing temperature, pH or ionic strength, a sustained and controlled release was observed due to the deformation of PEC micelles. Adding glutaraldehyde, a chemical crosslinking reagent, was an efficient way to reinforce the micelles structure and decrease the initial burst release. Cytotoxicity assays showed that drug‐loaded PEC micelles retained higher cell inhibition efficiency in HeLa cells. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2163–2172, 2014.
Biosynthetic hydrogels—Studies on chemical and physical characteristics on long‐term cellular response for tissue engineering
Authors: Thankam Finosh Gnanaprakasam , Muthu Jayabalan 
Published: July 2013

AbstractBiosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate ‐ poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA‐A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA‐A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA‐A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long‐term viability of around 250% after the 24th day of culture. All these qualities make PA‐A hydrogel form a potent candidate for cardiac tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2238–2247, 2014.
Polyethyleneimine Solubilized Luminescent Au(I)‐Thiolate Complexes for Highly Sensitive and Selective Cyanide Anion Sensing
Authors: Du Yi , Yuan Zhiqin , Xu Dong , Cai Na , He Yan , Yeung Edward S. 
Published: July 2013

AbstractCyanide (CN−) is a highly toxic anion to human beings, exploring efficient probes for sensitive and selective detection of it is very important. In this study, we explore a simple one‐pot reaction to synthesize polyethyleneimine (PEI) solubilized Au(I)‐MUA (11‐mercaptoundecanoic acid) complexes under mild condition. The as prepared Au(I)‐MUA complexes exhibit strong red photoluminescence (PL) and can act as sensitive and selective CN− optical sensor in aqueous media based on the chemical reaction between CN− and gold atom that quench the fluorescence, and the limit of detection is 10 nM, which is ∼270 times lower than the maximum contamination level (2.7 μM) in drinking water permitted by WHO. Additionally, real water sample from a local lake is tested with these optical sensors, and the PL variation caused by 0.1 μ CN− can be observed.
Exergy as a tool for measuring process intensification in chemical engineering
Authors: Luis Patricia 
Published: July 2013

AbstractExergy is defined as the maximum shaft work that can be done in a process to bring the system into equilibrium with the environment. Thus, exergy analyses are the first step to understand where the weak points of processes are. It considers intrinsically the quality of energy: when energy loses its quality, exergy is destroyed. In addition, optimization of processes aiming at the minimization of exergy destruction can be done as a function of the topology and physical characteristics of the system, such as finite dimensions, shapes, materials, finite speeds, and finite‐time intervals of operation, establishing a direct relationship between exergy and process intensification. However, the emphasis on exergy in chemical engineering is still very poor compared with other fields, in spite of being one of the areas in which more exergy is destroyed due to reaction and separation.This paper gives an overview of the current application of exergy analyses in chemical engineering, showing the main fields in which exergy studies are performed and focusing the attention on two critical points of action: separation technologies (distillation and membrane technology) and CO2 capture. New research trends in chemical engineering using exergy as a tool for process intensification are highlighted. © 2013 Society of Chemical Industry
On Maximum Edge Cuts of Connected Digraphs
Authors: Chen Guantao , Gu Manzhan , Li Nana 
Published: July 2013

AbstractA set F of edges in a digraph D is called a directed cut if there exists a nontrivial partition of such that F consists of all directed edges from X to Y. Let denote the maximum size of a directed cut of D, and let be the set of all digraphs D such that or for any vertex v in D. We show that for any connected digraph , which provides a positive answer to a problem of Lehel, Maffray, and Preissmann. Additionally, we consider triangle‐free digraphs in and answer another question of theirs.
How transformational leadership influences follower helping behavior: The role of trust and prosocial motivation
Authors: Zhu Yue , Akhtar Syed 
Published: July 2013

SummaryWe proposed and tested a moderated mediation model that jointly examines affect‐based and cognition‐based trust as the mediators and prosocial motivation as the moderator in relationships between transformational leadership and followers’ helping behavior towards coworkers. Data were collected from 348 sales and servicing employees and their supervisors in four private retail companies and five private manufacturing companies located in Southeast China. The results showed that both affect‐based trust and cognition‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers. Furthermore, moderated mediation analyses showed that affect‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers only among employees with high prosocial motivation, whereas cognition‐based trust mediated this relationship among only those with low prosocial motivation. Implications for the theory and practice of leadership are then discussed. Copyright © 2013 John Wiley & Sons, Ltd.