bluuebunny/crossref_metadata_2025 huggingface dataset:
Emitting electron spectra and acceleration processes in the jet of PKS 0447−439
Authors: Zhou Yao , Yan Dahai , Dai Benzhong , Zhang Li
Published: February 2014

We investigate the electron energy distributions (EEDs) and the corresponding acceleration processes in the jet of PKS 0447−439, and estimate its redshift through modeling its observed spectral energy distribution (SED) in the frame of a one-zone synchrotron-self Compton (SSC) model. Three EEDs formed in different acceleration scenarios are assumed: the power-law with exponential cut-off (PLC) EED (shock-acceleration scenario or the case of the EED approaching equilibrium in the stochastic-acceleration scenario), the log-parabolic (LP) EED (stochastic-acceleration scenario and the acceleration dominating), and the broken power-law (BPL) EED (no acceleration scenario). The corresponding fluxes of both synchrotron and SSC are then calculated. The model is applied to PKS 0447−439, and modeled SEDs are compared to the observed SED of this object by using the Markov Chain Monte Carlo method. The results show that the PLC model fails to fit the observed SED well, while the LP and BPL models give comparably good fits for the observed SED. The results indicate that it is possible that a stochastic acceleration process acts in the emitting region of PKS 0447−439 and the EED is far from equilibrium (acceleration dominating) or no acceleration process works (in the emitting region). The redshift of PKS 0447−439 is also estimated in our fitting: z = 0.16 ± 0.05 for the LP case and z = 0.17 ± 0.04 for BPL case.
Proteomic analysis of cap-dependent translation identifies LARP1 as a key regulator of 5′TOP mRNA translation
Authors: Tcherkezian Joseph , Cargnello Marie , Romeo Yves , Huttlin Edward L. , Lavoie Genevieve , Gygi Steven P. , Roux Philippe P.
Published: February 2014

The mammalian target of rapamycin (mTOR) promotes cell growth and proliferation by promoting mRNA translation and increasing the protein synthetic capacity of the cell. Although mTOR globally promotes translation by regulating the mRNA 5′ cap-binding protein eIF4E (eukaryotic initiation factor 4E), it also preferentially regulates the translation of certain classes of mRNA via unclear mechanisms. To help fill this gap in knowledge, we performed a quantitative proteomic screen to identify proteins that associate with the mRNA 5′ cap in an mTOR-dependent manner. Using this approach, we identified many potential regulatory factors, including the putative RNA-binding protein LARP1 (La-related protein 1). Our results indicate that LARP1 associates with actively translating ribosomes via PABP and that LARP1 stimulates the translation of mRNAs containing a 5′ terminal oligopyrimidine (TOP) motif, encoding for components of the translational machinery. We found that LARP1 associates with the mTOR complex 1 (mTORC1) and is required for global protein synthesis as well as cell growth and proliferation. Together, these data reveal important molecular mechanisms involved in TOP mRNA translation and implicate LARP1 as an important regulator of cell growth and proliferation.
Nucleosome loss leads to global transcriptional up-regulation and genomic instability during yeast aging
Authors: Hu Zheng , Chen Kaifu , Xia Zheng , Chavez Myrriah , Pal Sangita , Seol Ja-Hwan , Chen Chin-Chuan , Li Wei , Tyler Jessica K.
Published: February 2014

All eukaryotic cells divide a finite number of times, although the mechanistic basis of this replicative aging remains unclear. Replicative aging is accompanied by a reduction in histone protein levels, and this is a cause of aging in budding yeast. Here we show that nucleosome occupancy decreased by 50% across the whole genome during replicative aging using spike-in controlled micrococcal nuclease digestion followed by sequencing. Furthermore, nucleosomes became less well positioned or moved to sequences predicted to better accommodate histone octamers. The loss of histones during aging led to transcriptional induction of all yeast genes. Genes that are normally repressed by promoter nucleosomes were most induced, accompanied by preferential nucleosome loss from their promoters. We also found elevated levels of DNA strand breaks, mitochondrial DNA transfer to the nuclear genome, large-scale chromosomal alterations, translocations, and retrotransposition during aging.
SOX9: a stem cell transcriptional regulator of secreted niche signaling factors
Authors: Kadaja Meelis , Keyes Brice E. , Lin Mingyan , Pasolli H. Amalia , Genander Maria , Polak Lisa , Stokes Nicole , Zheng Deyou , Fuchs Elaine
Published: February 2014

Hair follicles (HFs) undergo cyclical periods of growth, which are fueled by stem cells (SCs) at the base of the resting follicle. HF-SC formation occurs during HF development and requires transcription factor SOX9. Whether and how SOX9 functions in HF-SC maintenance remain unknown. By conditionally targeting Sox9 in adult HF-SCs, we show that SOX9 is essential for maintaining them. SOX9-deficient HF-SCs still transition from quiescence to proliferation and launch the subsequent hair cycle. However, once activated, bulge HF-SCs begin to differentiate into epidermal cells, which naturally lack SOX9. In addition, as HF-SC numbers dwindle, outer root sheath production is not sustained, and HF downgrowth arrests prematurely. Probing the mechanism, we used RNA sequencing (RNA-seq) to identify SOX9-dependent transcriptional changes and chromatin immunoprecipitation (ChIP) and deep sequencing (ChIP-seq) to identify SOX9-bound genes in HF-SCs. Intriguingly, a large cohort of SOX9-sensitive targets encode extracellular factors, most notably enhancers of Activin/pSMAD2 signaling. Moreover, compromising Activin signaling recapitulates SOX9-dependent defects, and Activin partially rescues them. Overall, our findings reveal roles for SOX9 in regulating adult HF-SC maintenance and suppressing epidermal differentiation in the niche. In addition, our studies expose a role for SCs in coordinating their own behavior in part through non-cell-autonomous signaling within the niche.
Processing-Body Movement in Arabidopsis Depends on an Interaction between Myosins and DECAPPING PROTEIN1
Authors: Steffens Alexandra , Jaegle Benjamin , Tresch Achim , Hülskamp Martin , Jakoby Marc
Published: February 2014

Processing (P)-bodies are cytoplasmic RNA protein aggregates responsible for the storage, degradation, and quality control of translationally repressed messenger RNAs in eukaryotic cells. In mammals, P-body-related RNA and protein exchanges are actomyosin dependent, whereas P-body movement requires intact microtubules. In contrast, in plants, P-body motility is actin based. In this study, we show the direct interaction of the P-body core component DECAPPING PROTEIN1 (DCP1) with the tails of different unconventional myosins in Arabidopsis (Arabidopsis thaliana). By performing coexpression studies with AtDCP1, dominant-negative myosin fragments, as well as functional full-length myosin XI-K, the association of P-bodies and myosins was analyzed in detail. Finally, the combination of mutant analyses and characterization of P-body movement patterns showed that myosin XI-K is essential for fast and directed P-body transport. Together, our data indicate that P-body movement in plants is governed by myosin XI members through direct binding to AtDCP1 rather than through an adapter protein, as known for membrane-coated organelles. Interspecies and intraspecies interaction approaches with mammalian and yeast protein homologs suggest that this mechanism is evolutionarily conserved among eukaryotes.
Structural and functional characterization of an Isd-type haem-degradation enzyme from Listeria monocytogenes
Authors: Duong Thao , Park Kwangsu , Kim Truc , Kang Sung Wook , Hahn Myung Joon , Hwang Hye-Yeon , Kim Kyeong Kyu
Published: February 2014

Bacterial pathogens have evolved diverse types of efficient machinery to acquire haem, the most abundant source of iron in the human body, and degrade it for the utilization of iron. Gram-positive bacteria commonly encode IsdG-family proteins as haem-degrading monooxygenases. Listeria monocytogenes is predicted to possess an IsdG-type protein (Lmo2213), but the residues involved in haem monooxygenase activity are not well conserved and there is an extra N-terminal domain in Lmo2213. Therefore, its function and mechanism of action cannot be predicted. In this study, the crystal structure of Lmo2213 was determined at 1.75 Å resolution and its haem-binding and haem-degradation activities were confirmed. Structure-based mutational and functional assays of this protein, designated as an Isd-type L. monocytogenes haem-degrading enzyme (Isd-LmHde), identified that Glu71, Tyr87 and Trp129 play important roles in haem degradation and that the N-terminal domain is also critical for its haem-degrading activity. The haem-degradation product of Isd-LmHde is verified to be biliverdin, which is also known to be the degradation product of other bacterial haem oxygenases. This study, the first structural and functional report of the haem-degradation system in L. monocytogenes, sheds light on the concealed haem-utilization system in this life-threatening human pathogen.
Improving the chances of successful protein structure determination with a random forest classifier
Authors: Jahandideh Samad , Jaroszewski Lukasz , Godzik Adam
Published: February 2014

Obtaining diffraction quality crystals remains one of the major bottlenecks in structural biology. The ability to predict the chances of crystallization from the amino-acid sequence of the protein can, at least partly, address this problem by allowing a crystallographer to select homologs that are more likely to succeed and/or to modify the sequence of the target to avoid features that are detrimental to successful crystallization. In 2007, the now widely usedXtalPredalgorithm [Slabinskiet al.(2007),Protein Sci.16, 2472–2482] was developed.XtalPredclassifies proteins into five `crystallization classes' based on a simple statistical analysis of the physicochemical features of a protein. Here, towards the same goal, advanced machine-learning methods are applied and, in addition, the predictive potential of additional protein features such as predicted surface ruggedness, hydrophobicity, side-chain entropy of surface residues and amino-acid composition of the predicted protein surface are tested. The newXtalPred-RF(random forest) achieves significant improvement of the prediction of crystallization success over the originalXtalPred. To illustrate this,XtalPred-RFwas tested by revisiting target selection from 271 Pfam families targeted by the Joint Center for Structural Genomics (JCSG) in PSI-2, and it was estimated that the number of targets entered into the protein-production and crystallization pipeline could have been reduced by 30% without lowering the number of families for which the first structures were solved. The prediction improvement depends on the subset of targets used as a testing set and reaches 100% (i.e.twofold) for the top class of predicted targets.
Promoting protein crystallization using a plate with simple geometry
Authors: Chen Rui-Qing , Yin Da-Chuan , Liu Yong-Ming , Lu Qin-Qin , He Jin , Liu Yue
Published: February 2014

Increasing the probability of obtaining protein crystals in crystallization screening is always an important goal for protein crystallography. In this paper, a new method called the cross-diffusion microbatch (CDM) method is presented, which aims to efficiently promote protein crystallization and increase the chance of obtaining protein crystals. In this method, a very simple crystallization plate was designed in which all crystallization droplets are in one sealed space, so that a variety of volatile components from one droplet can diffuse into any other droplet via vapour diffusion. Crystallization screening and reproducibility tests indicate that this method could be a potentially powerful technique in practical protein crystallization screening. It can help to obtain crystals with higher probability and at a lower cost, while using a simple and easy procedure.
Conformational transitions in the γ subunit of the archaeal translation initiation factor 2
Authors: Nikonov Oleg , Stolboushkina Elena , Arkhipova Valentina , Kravchenko Olesya , Nikonov Stanislav , Garber Maria
Published: February 2014

In eukaryotes and archaea, the heterotrimeric translation initiation factor 2 (e/aIF2) is pivotal for the delivery of methionylated initiator tRNA (Met-tRNAi) to the ribosome. It acts as a molecular switch that cycles between inactive (GDP-bound) and active (GTP-bound) states. Recent studies show that eIF2 can also exist in a long-lived eIF2γ–GDP–Pi (inorganic phosphate) active state. Here, four high-resolution crystal structures of aIF2γ from Sulfolobus solfataricus are reported: aIF2γ–GDPCP (a nonhydrolyzable GTP analogue), aIF2γ–GDP–formate (in which a formate ion possibly mimics Pi), aIF2γ–GDP and nucleotide-free aIF2γ. The structures describe the different states of aIF2γ and demonstrate the conformational transitions that take place in the aIF2γ `life cycle'.
Structure of a proteolytically resistant analogue of (NLys)5SFTI-1 in complex with trypsin: evidence for the direct participation of the Ser214 carbonyl group in serine protease-mediated proteolysis
Authors: Krzywda Szymon , Jaskolski Mariusz , Rolka Krzysztof , Stawikowski Maciej J.
Published: February 2014

Peptide–peptoid hybrids are found to be potent inhibitors of serine proteases. These engineered peptidomimetics benefit from both types of units of the biopolymeric structure: the natural inhibitor part serves as a good binding template, while the P1-positioned peptoid component provides complete resistance towards proteolysis. In this report, the mechanism of proteolytic resistance of a P1 peptoid-containing analogue is postulated based on the crystal structure of the (NLys)5-modified sunflower trypsin inhibitor SFTI-1 in complex with bovine trypsin solved at 1.29 Å resolution. The structural differences between the (NLys)5SFTI-1–trypsin complex and the native SFTI-1–trypsin complex are surprisingly small and reveal the key role of the carbonyl group of the Ser214 residue of the enzyme, which is crucial for binding of the inhibitor and plays a crucial role in proteolysis mediated by serine proteases. The incorporated NLys5 peptoid residue prevents Ser214 from forming a hydrogen bond to the P1 residue, and in turn Gln192 does not form a hydrogen bond to the carbonyl group of the P2 residue. It also increases the distance between the Ser214 carbonyl group and the Ser195 residue, thus preventing proteolysis. The hybrid inhibitor structure reported here provides insight into protein–protein interaction, which can be efficiently and selectively probed with the use of peptoids incorporated within endogenous peptide ligands.
Exploiting large non-isomorphous differences for phase determination of a G-segment invertase–DNA complex
Authors: Ritacco Christopher J. , Steitz Thomas A. , Wang Jimin
Published: February 2014

Crystals of the G-segment invertase in complex with a 37-base-pair asymmetric DNA duplex substrate had an unusually high solvent content of 88% and diffracted to a maximal resolution of about 5.0 Å. These crystals exhibited a high degree of non-isomorphism and anisotropy, which presented a serious challenge for structure determination by isomorphous replacement. Here, a procedure of cross-crystal averaging is described that uses large non-isomorphous crystallographic data with a priori information of an approximate molecular boundary as determined from a minimal amount of experimental phase information. Using this procedure, high-quality experimental phases were obtained that have enabled it to be shown that the conformation of the bound substrate DNA duplex significantly differs from those of substrates bound in other serine recombinase–DNA complexes.
Structures of the Ca2+-regulated photoprotein obelin Y138F mutant before and after bioluminescence support the catalytic function of a water molecule in the reaction
Authors: Natashin Pavel V. , Ding Wei , Eremeeva Elena V. , Markova Svetlana V. , Lee John , Vysotski Eugene S. , Liu Zhi-Jie
Published: February 2014

Ca2+-regulated photoproteins, which are responsible for light emission in a variety of marine coelenterates, are a highly valuable tool for measuring Ca2+ inside living cells. All of the photoproteins are a single-chain polypeptide to which a 2-hydroperoxycoelenterazine molecule is tightly but noncovalently bound. Bioluminescence results from the oxidative decarboxylation of 2-hydroperoxycoelenterazine, generating protein-bound coelenteramide in an excited state. Here, the crystal structures of the Y138F obelin mutant before and after bioluminescence are reported at 1.72 and 1.30 Å resolution, respectively. The comparison of the spatial structures of the conformational states of Y138F obelin with those of wild-type obelin gives clear evidence that the substitution of Tyr by Phe does not affect the overall structure of both Y138F obelin and its product following Ca2+ discharge compared with the corresponding conformational states of wild-type obelin. Despite the similarity of the overall structures and internal cavities of Y138F and wild-type obelins, there is a substantial difference: in the cavity of Y138F obelin a water molecule corresponding to W2 in wild-type obelin is not found. However, in Ca2+-discharged Y138F obelin this water molecule now appears in the same location. This finding, together with the observed much slower kinetics of Y138F obelin, clearly supports the hypothesis that the function of a water molecule in this location is to catalyze the 2-hydroperoxycoelenterazine decarboxylation reaction by protonation of a dioxetanone anion before its decomposition into the excited-state product. Although obelin differs from other hydromedusan Ca2+-regulated photoproteins in some of its properties, they are believed to share a common mechanism.
Structural evidence for the partially oxidized dipyrromethene and dipyrromethanone forms of the cofactor of porphobilinogen deaminase: structures of the Bacillus megaterium enzyme at near-atomic resolution
Authors: Azim N. , Deery E. , Warren M. J. , Wolfenden B. A. A. , Erskine P. , Cooper J. B. , Coker A. , Wood S. P. , Akhtar M.
Published: February 2014

The enzyme porphobilinogen deaminase (PBGD; hydroxymethylbilane synthase; EC 2.5.1.61) catalyses an early step of the tetrapyrrole-biosynthesis pathway in which four molecules of the monopyrrole porphobilinogen are condensed to form a linear tetrapyrrole. The enzyme possesses a dipyrromethane cofactor, which is covalently linked by a thioether bridge to an invariant cysteine residue (Cys241 in the Bacillus megaterium enzyme). The cofactor is extended during the reaction by the sequential addition of the four substrate molecules, which are released as a linear tetrapyrrole product. Expression in Escherichia coli of a His-tagged form of B. megaterium PBGD has permitted the X-ray analysis of the enzyme from this species at high resolution, showing that the cofactor becomes progressively oxidized to the dipyrromethene and dipyrromethanone forms. In previously solved PBGD structures, the oxidized cofactor is in the dipyromethenone form, in which both pyrrole rings are approximately coplanar. In contrast, the oxidized cofactor in the B. megaterium enzyme appears to be in the dipyrromethanone form, in which the C atom at the bridging α-position of the outer pyrrole ring is very clearly in a tetrahedral configuration. It is suggested that the pink colour of the freshly purified protein is owing to the presence of the dipyrromethene form of the cofactor which, in the structure reported here, adopts the same conformation as the fully reduced dipyrromethane form.
r-1,t-3-Bis[4-(dimethylamino)phenyl]-c-2,t-4-bis(pyridin-4-yl)cyclobutane
Authors: Zhang Shuguang , Zhuang Junpeng
Published: February 2014

The title compound, C30H32N4, was synthesized by the photodimerization oftrans-4-{2-[4-(dimethylamino)phenyl]ethenyl}pyridine in benzene upon irradiation with UV light. This photodimer has a puckered cyclobutane ring with the four aryl substituents in anr-1,t-2,c-3,tconformation. The puckering angle of the cyclobutane ring is 32.22 (7)°, which is the largest among reported tetraaryl-substituted cyclobutanes. In the crystal, the molecules form a hollow, one-dimensional structure extending parallel to thecaxisviatwo different pairs of C—H...π interactions.
N1,N4-Diphenyl-3,6-bis(phenylimino)cyclohexa-1,4-diene-1,4-diamine
Authors: Ohno Keiji , Maruyama Haruki , Fujihara Takashi , Nagasawa Akira
Published: February 2014

In the title compound, C30H24N4, the central benzoquinonediimine moiety is approximately planar, with a maximum deviation of 0.044 (14) Å. The four terminal phenyl rings are twisted by 44.95 (11), 54.90 (10), 44.98 (10) and 50.68 (11)° with respect to the mean plane the benzoquinonediimine unit. In the crystal, molecules are linked by weak C—H...π interactions into supramolecular chains running along theb-axis direction.
4-Hydroxy-5-methoxy-N,1-dimethyl-2-oxo-N-[4-(trifluoromethyl)phenyl]-1,2-dihydroquinoline-3-carboxamide
Authors: Akinboye Emmanuel S. , Butcher Ray J. , Yildirim Sema Ozturk , Isaacs John T.
Published: February 2014

The title compound, C20H17F3N2O4, named tasquinimod, is a second-generation oral quinoline-3-carboxamide analogue, which is currently in phase III clinical trials for the treatment of metastatic prostate cancer. The quinoline unit is almost planar (r.m.s. deviation of fitted atoms = 0.0075 Å). The carboxamide side chain, substituted at position 3, is tilted by 88.07 (7)° to the quinoline plane. Both the methyl and carbonyl groups of this carboxamide side chain are in asynconformation. The 4-(trifluoromethyl)phenyl plane is inclined at 50.62 (17)° to the plane of the carboxamide side chain, and at 87.14 (4)° to the plane of the quinoline ring system. The 4-hydroxy H atom acts as a double proton donor in an intramolecular hydrogen bond to the 5-position methoxy O atom and in an intermolecular contact to the 2-oxo group, generating a chain along [010] in the crystal structure.
5-Bromo-3-cyclohexylsulfinyl-2,4,6-trimethyl-1-benzofuran
Authors: Choi Hong Dae , Seo Pil Ja , Lee Uk
Published: February 2014

In the title compound, C17H21BrO2S, the cyclohexyl ring adopts a chair conformation and the arylsulfinyl unit is positioned equatorially relative to the cyclohexyl group. The benzofuran unit is essentially planar, with an r.m.s. deviation of 0.016 (2) Å. In the crystal, molecules are linked by weak C—H...O, C—H...π and Br...π [3.663 (2) Å] interactions, resulting in a three-dimensional network. A Br...Br [3.6838 (6) Å] contact is observed. The O atom of the sulfinyl group is disordered over two orientations with an occupancy ratio of 0.863 (5):0.137 (5).
2-{(E)-[4-(Diphenylamino)phenyl]iminomethyl}phenol
Authors: Chen Jiang , Jin Zhe-Peng , Gao Bing-Fei , Yu Jian-Hua , Wu Jie-Ying
Published: February 2014

The asymmetric unit of the title Schiff base molecule, C25H20N2O, contains two independent molecules. In each molecule, the C=N bond is in anEconformation. The most significant difference between the two molecules is seen for the dihedral angles between the methoxy-substituted benzene ring and the two phenyl rings, which are 85.5 (1) and 82.3 (1)° in the first molecule, and 49.0 (1) and 40.4 (1)° in the second. This conformational difference is reflected in the central C=N—C...;C torsion angle, which is 28.7 (2)° in the first molecule and −29.8 (3)° in the other. In each molecule, there is an intramolecular O—H...N hydrogen bond.
2-((E)-{4-[Bis(4-ethoxyphenyl)amino]phenyl}iminomethyl)phenol
Authors: Gao Bing-Fei , Jin Zhe-Peng , Chen Jiang , Tian Yu-Peng
Published: February 2014

In the title Schiff base molecule, C29H28N2O3, the three terminal benzene rings are twisted by 73.84 (15), 81.25 (16) and 12.1 (2)° with respect to the central benzene ring. An intramolecular O—H...N hydrogen bond occurs. In the crystal, molecules are linkedviaweak C—H...π interactions into a three-dimensional supramolecular architecture.
The study of the price of gold futures based on heterogeneous investors' overconfidence
Authors: Jiang Wei , Luan Pupu , Yang Chunpeng
Published: February 2014

Purpose

– The purpose of this paper is to research and analyze the price of gold futures based on heterogeneous investors' overconfidence.

Design/methodology/approach

– This paper divides the traders of gold futures market into two kinds: the speculators and arbitrageurs, and then constructs a market equilibrium model of futures pricing to analyze the behaviors of the two kinds of traders with overconfidence. After getting the decision-making function, the market equilibrium futures price is attained on the condition of market clearing. Then, this paper analyzes how the overconfidence impacts on futures price, volatility of the price of gold futures and the effects on individual utility.

Findings

– Under different market conditions, the overconfidence psychological impacts of heterogeneous investor on the price and volatility of futures are different, sometimes completely opposite.

Originality/value

– In the past literature, the relationships between overconfidence and the price or volatility are positive; however, the study shows that sometimes it is positive, and sometimes it is negative.
Stagnation-point flow of Jeffrey fluid with melting heat transfer and Soret and Dufour effects
Authors: Hayat T. , Iqbal Z. , Mustafa M. , Alsaedi A.
Published: February 2014

Purpose

– This investigation has been carried out for thermal-diffusion (Dufour) and diffusion-thermo (Soret) effects on the boundary layer flow of Jeffrey fluid in the region of stagnation-point towards a stretching sheet. Heat transfer occurring during the melting process due to a stretching sheet is considered. The paper aims to discuss these issues.

Design/methodology/approach

– The authors convert governing partial differential equations into ordinary differential equations by using suitable transformations. Analytic solutions of velocity and temperature are found by using homotopy analysis method (HAM). Further graphs are displayed to study the salient features of embedding parameters. Expressions of skin friction coefficient, local Nusselt number and local Sherwood number have also been derived and examined.

Findings

– It is found that velocity and the boundary layer thickness are increasing functions of viscoelastic parameter (Deborah number). An increase in the melting process enhances the fluid velocity. An opposite effect of melting heat process is noticed on velocity and skin friction.

Practical implications

– The boundary layer flow in non-Newtonian fluids is very important in many applications including polymer and food processing, transpiration cooling, drag reduction, thermal oil recovery and ice and magma flows. Further, the thermal diffusion effect is employed for isotope separation and in mixtures between gases with very light and medium molecular weight.

Originality/value

– Very scarce literature is available on thermal-diffusion (Dufour) and diffusion-thermo (Soret) effects on the boundary layer flow of Jeffrey fluid in the region of stagnation-point towards a stretching sheet with melting heat transfer. Series solution is developed using HAM. Further, the authors compare the present results with the existing in literature and found excellent agreement.
Study on constitutive model of coupled damage-permeability of porous media
Authors: Xinhua Xue , Wohua Zhang , Yang Xingguo
Published: February 2014

Purpose

– The paper aims to clarify the relationship between the micro-structures of porous media and the coefficient of permeability. Most materials involve different types of defects like caves, pores and cracks, which are important characters of porous media and have a great influence on the physical properties of materials. To study the seepage mechanical characteristics of damaged porous media, the constitutive model of porous media dealing with coupled modeling of pores damage and its impact on permeability property of a deforming media was studied in this paper.

Design/methodology/approach

– The paper opted for an exploratory study using the approach of continuum damage mechanics (CDM).

Findings

– The paper provides some new insights on the fluid dynamics of porous media. The dynamic evolution model of permeability coefficient established in this paper can be used to model the fluid flow problems in damaged porous media. Moreover, the modified Darcy's law developed in this paper is considered to be an extension of the Darcy's law for fluid flow and seepage in a porous medium.

Research limitations/implications

– Owing to the limitations of time, conditions, funds, etc., the research results should be subject to multifaceted experiments before their innovative significance can be fully verified.

Practical implications

– The paper includes implications for the development of fluid dynamics of porous media.

Originality/value

– This paper fulfils an identified need to study the relationship between the micro-structures of porous media and the coefficient of permeability.
Numerical and analytical solutions for Falkner-Skan flow of MHD Oldroyd-B fluid
Authors: Abbasbandy S. , Hayat T. , Alsaedi A. , Rashidi M.M.
Published: February 2014

Purpose

– In this paper, analysis is presented to investigate the Falkner-Skan flow of magnetohydrodynamic (MHD) Oldroyd-B fluid. The paper aims to discuss these issues.

Design/methodology/approach

– In this paper, the authors used two methods: homotopy analysis method and numerical Keller-box method.

Findings

– It is observed that skin friction coefficient in Oldroyd-B fluid is larger when compared with viscous fluid. Further, the relaxation and retardation times have opposite effects on the velocity components.

Practical implications

– A comparative study between the series and numerical solutions for the skin friction is shown in the paper. The results indicated that both solutions are in well agreement.

Originality/value

– This model is investigated for the first time, as the authors know.
Exact solutions of fractional heat-like and wave-like equations with variable coefficients
Authors: Tang Bo , Wang Xuemin , Wei Leilei , Zhang Xindong
Published: February 2014

Purpose

– This paper aims to apply fractional variational iteration method using He's polynomials (FVIMHP) to obtain exact solutions for variable-coefficient fractional heat-like and wave-like equations with fractional order initial and boundary conditions.

Design/methodology/approach

– The approach is based on FVIMHP. The authors choose as some examples to illustrate the validity and the advantages of the method.

Findings

– The results reveal that the FVIMHP method provides a very effective, convenient and powerful mathematical tool for solving fractional differential equations.

Originality/value

– The variable-coefficient fractional heat-like and wave-like equations with fractional order initial and boundary conditions are solved first. Illustrative examples are included to demonstrate the validity and applicability of the method.
Modeling defects in castings using a volume of fluid method
Authors: Zhang Sailei , Yanke Jeffrey , R. Johnson David , J.M. Krane Matthew
Published: February 2014

Purpose

– A single-domain multi-phase model is developed for macrosegregation and shrinkage pipe formation in castings, as functions of buoyancy- and shrinkage-induced flow. The paper aims to discuss these issues.

Design/methodology/approach

– Using a volume of fluid (VOF) method, both the air/liquid and air/solid interfaces are tracked during shrinkage pipe formation. A set of mixture advection-diffusion equations are derived and solved for velocity, temperature, composition, and phase field evolution. The fluid mechanics of the model are verified using a transient ditch drainage problem.

Findings

– Results showing the interaction of macrosegregation and pipe formation are presented for two alloys under faster and slower cooling conditions.

Originality/value

– This model provides a comprehensive tool to investigate relationships between the developing composition distribution and shrinkage pipe formation.
PhotoBox focuses on employees' strengths
Authors: Farry Michael
Published: February 2014

Purpose

– Reveals how line managers who play to their strengths and are noted for their positive leadership qualities are fostering a positive and energizing culture with high levels of accountability and performance at PhotoBox, a UK online photo service.

Design/methodology/approach

– Explains that PhotoBox managers took part in workshops combining a focus on personal growth and relevant skills development, in which core modules included a positive-leadership master-class and workshops on strengths coaching for results and engaging one-to-ones.

Findings

– Reveals that the master-class helped people to identify their unique strengths as a set of personal qualities that energize and lead to productive habits. The session also helped people to move from simple awareness of strengths to applying them in the role of manager. In turn, the groups created a shared vision for a more people-centric approach to leading across PhotoBox.

Research limitations/implications

– Explains that the new accent on personal strengths has benefited teamwork at the company, too.

Originality/value

– Spotlights how playing to individuals' strengths improves teamwork, communication and organizational performance.
Confidence that stops short of arrogance is the key to call-center success
Authors: Drake-Knight Nick
Published: February 2014

Purpose

– Emphasizes the importance of self-confidence in sales people and reveals how these employees can achieve confidence in their call-center roles.

Design/methodology/approach

– Puts forward a series of spidergrams illustrating the self-confidence of different employees and suggests how they can improve their performance.

Findings

– Advances the view that sales people need to: know their products and services; know their sales and customer-service processes; know how to get inside the world of prospective customers; know their competitors' products and services; know what has worked, and not worked, in the past; and have faith and belief in the product, service and brand.

Practical implications

– Outlines development activities for call-center employees, concentrating on knowledge of product, sales process, customer-service processes, competitors' products and performance and the customer's world.

Originality/value

– Provides a tool-kit for developing call-center skills.
Twenty-one steps to successful leadership
Authors: Rao M.S.
Published: February 2014

Purpose

– Presents 21 tools to coach future leaders.

Design/methodology/approach

– Highlights the effects of Baby Boomers leaving senior positions and prepares organizations to spot the characteristics of future leaders.

Findings

– Emphasizes the importance of setting a broad vision and developing a global mindset.

Practical implications

– Stresses the key role of learning continuously and of blending soft skills and business acumen, to achieve leadership excellence.

Originality/value

– Describes how to develop the leadership skills of tomorrow.
Investigation and assessment of photoluminescent embroidered elements
Authors: Radavičiene S. , Jucienė M. , Sacevičiene V. , Sacevičius R. , Otas K.
Published: February 2014

Purpose

– The purpose of this paper is to determine conformity of geometrical parameters between the elements embroidered with photoluminescent threads and their digital images as well as to explore the change in photoluminescent radiation.

Design/methodology/approach

– Using some different methodologies and apparatus, analysis shape of embroidered elements conformity and photoluminescent luminance attenuation are analysed.

Findings

– The provided methodologies allow assessing the quality of embroidered elements area and photoluminescent properties.

Originality/value

– The proposed approach can be adjusted to investigate photoluminescent properties of embroidered elements of different filling types.
Designing of engineered fabrics using particle swarm optimization
Authors: Das S. , Ghosh A. , Banerjee D.
Published: February 2014

Purpose

– The purpose of this paper is to design woven fabrics with desired quality and low manufacturing cost by optimizing the weave parameters such as count, crimp and thread spacing of warp and weft yarns.

Design/methodology/approach

– To fulfill this goal, the authors endeavor to devise a searching mechanism based on particle swarm optimization (PSO) for efficiently finding the appropriate combination of weave parameters.

Findings

– The experimental validation confirms that the proposed method has an excellent search capacity to obtain the best combinations of weave parameters for producing the fabrics with requisite quality at low cost.

Practical implications

– The quick response capability of the system would benefit the fabric manufacturers for efficient determination of the required weaving parameters to produce the engineered fabrics.

Originality/value

– This paper offers a maiden application of PSO technique to design engineered products in textiles. The method is easy to implement and it is computationally inexpensive as fewer parameters are involved.
Investigation into the feasibility of inductively coupled antenna for use in smart clothing
Authors: Suh Minyoung , E. Carroll Katherine , Grant Edward , Oxenham William
Published: February 2014

Purpose

– This research investigated the feasibility of using an inductively coupled antenna as the basis of applying a systems approach to smart clothing. In order to simulate real-life situations, the impact of the distortions and relative displacement of different fabric layers (with affixed antennas) on the signal quality was assessed. The paper aims to discuss these issues.

Design/methodology/approach

– A spiral antenna was printed on different fabric substrates. Obstructive conditions of the inductively coupled fabric layers were investigated to find out how much influence these conditions had on transmission performance. Reflected signals and transmitted signals were observed, while fabric antennas were subjected to displacement (distance and dislocation) or deformation (stretching and bending). The threshold of physical obstacles was estimated based on statistical analyses.

Findings

– The limits of physical conditions that enable proper wireless transmission were estimated up to ∼2 cm for both distance and dislocation, and ∼0.24 K for bending deformation. The antenna performance remained within an acceptable level of 20 percent transmission up to 10 percent fabric stretch. Based on well-established performance metrics used in clothing environment on the body, which employs 2-5 cm of ease, the results imply that the inductively coupled antennas may be suitable for use in smart clothing.

Originality/value

– This research demonstrates that the use of inductively coupled antennas on multiple clothing layers could offer the basis of a new “wireless” system approach to smart clothing. This would not only result in performance benefits, but would also significantly improve the aesthetics of smart clothing which should result in new markets for such products.
Synthesis, characterization and tribological behavior of oleic acid-capped core-shell lanthanum borate-SiO2 composites
Authors: Jia Zhengfeng , Xia Yan-qiu , Shao Xin , Du San-ming
Published: February 2014

Purpose

– The purpose of this paper is to investigate the tribological properties of poly-alpha-olefin (PAO) with nano/microstructure core-shell lanthanum borate-SiO2 composites (OCLS).

Design/methodology/approach

– Oleic acid-capped core-shell lanthanum borate-SiO2 composites were synthesized by an easy way. The composites were characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The friction and wear behaviors of the quenched AISI 1045 steel specimens sliding against AISI 52100 steel under the lubrication of PAO containing OCLS were comparatively investigated with PAO containing SiO2 additive on an Optimol SRV reciprocating friction and wear tester. On the other hand, the tribological properties of the PAO containing OCLS were also investigated on four-ball tester.

Findings

– The diameter of OCLS was about 20 nm, and the thickness of the SiO2 shell was less than 5 nm. The ratio of oleic acid (OA) is about 15 percent. The PAO containing OCLS possesses much better tribological properties than that of pure PAO and PAO containing SiO2 additive.

Originality/value

– The PAO+OCLS possess a better friction reducing and antiwear properties than pure PAO. The new additive can improve the tribological ability of machinery.
On frictional performance of sintering materials used by mechanical seals in water
Authors: Liu Ying , Zhao Xingyu , Wen Qingfeng , Wang Yuming
Published: February 2014

Purpose

– It is aiming at finding tribology performance laws and mechanism of sintering materials, including new materials, which are popular or potential materials of mechanical seals working under water condition with different working parameters, involving load and sliding speed.

Design/methodology/approach

– Falex-1506 tribo-machine has been used. The upper sample is rotated against the stationary sample below. They are all rings. The samples are WNV2, sintered pressureless bonded; CHV1, graphite-added PLSiC; R, sintered reaction bonded; R2, graphite-added RBSiC, cemented carbide YN6 and graphite MSMG. Twenty kinds of hard/hard and soft/hard pairs were tested under water condition. Then, SEM was used to observe the sliding surface to explain their rubbing mechanism.

Findings

– Friction coefficients decrease with the load increasing under water lubrication due to water holding by small holes on their surface. But the friction coefficients have no change with the varying of velocity. The hard alloy/sintered silicon carbon pairs may be better choice, where the lowest friction coefficient is only about 0.02, than soft/hard or silicon carbon/silicon carbon pairs under water lubrication, especially under heavy load.

Research limitations/implications

– The test was carried under load from 89 N (0.7 MPa) to 356 N (2.80 MPa) and sliding velocity from 0.746 to 5.074 m/s where the lubrication is in mixed.

Originality/value

– The detailed values of frictional coefficients of popular and potential sintered material of mechanical seals working under water lubrication were given by the experimental research which may be helpful for the choice of mechanical seal materials.
PMI: mortgage backstop from the Alger Report to Dodd-Frank
Authors: Neidermeyer Adolph , E. Boyd Naomi , Neidermeyer Presha
Published: February 2014

Purpose

– The purpose of this paper is to provide a historical perspective and going-forward assessment of the importance of private mortgage insurance (PMI) entities in the residential-lending landscape in the USA.

Design/methodology/approach

– Financial data from the PMI entities and federal income tax data were analyzed to comment on the importance of the PMI entities in the historical and current mortgage-lending environment.

Findings

– PMI entities played a critical role in expanding the population of mortgage candidates for financial institutions. Through the guarantees offered by PMI entities, financial institutions granted loans to individuals who otherwise would not have qualified for mortgages.

Originality/value

– No prior research has assessed the overall historical role played by these primary PMI entities.
Stock price discreteness and clustering: decimals and ordered probit model
Authors: Kim Haksoon
Published: February 2014

Purpose

– The purpose of this paper is to revisit the ordered probit model of Hausman et al. after the NYSE decimalization.

Design/methodology/approach

– The changed ordered probit model.

Findings

– The model can somewhat capture the different impact of trading-related “explanatory” variables on price changes among three different decimals but does not explain much about price discreteness and irregular transaction intervals among the existing models of stock price discreteness. Overall 1/16th and 1/24th range of the dependent variable is better explained by trading-related explanatory variables than 1/8th range of the dependent variable for small firms and there is not much difference in large firms among three decimals. The results imply that finer specification in decimalization and smaller firm size matters in trading after the decimalization project.

Originality/value

– First paper to revisit the ordered probit model of Hausman et al. after the NYSE decimalization.
The influences of sales compensations, management stringency and ethical evaluations on product recommendations made by insurance brokers
Authors: Tseng Lu-Ming , Kang Yue-Min
Published: February 2014

Purpose

– The purpose of this paper is to explore the impacts of the size and timing of sales compensations, the management stringency of the insurer and the insurance broker's own moral views on product recommendations made by the brokers.

Design/methodology/approach

– The data used in this research were gathered from life insurance broker companies in Taiwan.

Findings

– The results showed that the sales compensations, perceived leniency of the insurer's underwriting and claim policy would affect the product recommendations made by the brokers.

Practical implications

– Insurance brokers are one of the most important marketing channels in the insurance industry. However, using the insurance brokers to sell insurance may result in some ethical problems. For example, some insurance brokers may sell insurance to high-risk customers because the high-risk customers may prefer to buy more insurance and that means more sales compensations can be earned. The findings of this research may have some implications for insurance management and insurance regulation.

Originality/value

– This study contributes to the understanding of insurance brokers' responses to adverse selection problems (high-risk customers may prefer to buy more insurance) and product recommendation decisions. The issue has been less mentioned in the financial regulation literature.