722 research outputs found

    Positioning variation modeling for aircraft panels assembly based on elastic deformation theory

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    Dimensional variation in aircraft panel assembly is one of the most critical issues that affects the aerodynamic performance of aircraft, due to elastic deformation of parts during the positioning and clamping process. This paper proposes an assembly deformation prediction model and a variation propagation model to predict the assembly variation of aircraft panels, and derives consecutive 3-D deformation expressions which explicitly describe the nonlinear behavior of physical interaction occurring in compliant components assembly. An assembly deformation prediction model is derived from equations of statics of elastic beam to calculate the elastic deformation of panel component resulted from positioning error and clamping force. A variation propagation model is used to describe the relationship between local variations and overall assembly variations. Assembly variations of aircraft panels due to positioning error are obtained by solving differential equations of statics and operating spatial transformations of the coordinate. The calculated results show a good prediction of variation in the experiment. The proposed method provides a better understanding of the panel assembly process and creates an analytical foundation for further work on variation control and tolerance optimization

    Electrodeposition of CuGaSe2 and CuGaS2 thin films for photovoltaic applications

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s10008-016-3237-0.Abstract CuGaSe2 and CuGaS2 polycrystalline thin film absorbers were prepared by one-step electrodeposition from an aqueous electrolyte containing CuCl2, GaCl3 and H2SeO3. The pH of the solution was adjusted to 2.3 by adding HCl and KOH. Annealing improved crystallinity of CuGaSe2 and further annealing in sulphur atmosphere was required to obtain CuGaS2 layers. The morphology, topography, chemical composition and crystal structure of the deposited thin films were analysed by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy and X-ray diffraction, respectively. X-Ray diffraction showed that the asdeposited CuGaSe2 film exhibited poor crystallinity, but which improved dramatically when the layers were annealed in forming gas atmosphere for 40 min. Subsequent sulphurization of CuGaSe2 films was performed at 400 °C for 10 min in presence of molecular sulphur and under forming gas atmosphere. The effect of sulphurization was the conversion of CuGaSe2 into CuGaS2. The formation of CuGaS2 thin films was evidenced by the shift observed in the X-ray diffraction pattern and by the blue shift of the optical bandgap. The bandgap of CuGaSe2 was found to be 1.66 eV, while for CuGaS2 it raised up to 2.2 eV. A broad intermediate absorption band associated to Cr and centred at 1.63 eV was observed in Cr-doped CuGaS2 films.This work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat Valenciana (Prometeus 2014/044). One of the authors (S. Ullah) acknowledges the European Union (IDEAS-Call-3, Innovation and Design for Euro-Asian scholars) for its financial support.Ullah, S.; Mollar GarcĂ­a, MA.; MarĂ­, B. (2016). Electrodeposition of CuGaSe2 and CuGaS2 thin films for photovoltaic applications. Journal of Solid State Electrochemistry. 20(8):2251-2257. https://doi.org/10.1007/s10008-016-3237-0S22512257208Calixto ME, Sebastian PJ, Bhattacharya RN, Noufi (1999) Sol Energ Mat Sol C 59:75–84Mandati S, Sarada BV, Dey SR, Joshi SV (2015) J Power Sources 273:149–157Jacobsson TJ, FjĂ€llström V, Edoff M, Edvinsson T (2015) Sol Energ Mat Sol C 134:185–193Carrete A, Placidi M, Shavel A, PĂ©rez RodrĂ­guez A, Cabot A (2015) Phys Stat Sol (a) 212:67–71Saji VS, Ik-Ho C, Lee CW (2011) Sol Energy 86:2666–2678Park MG, Ahn SJ, Yun JH, Gwak J, Cho A, Ahn SK, Shin K, Nam D, Cheong H, Yoon K (2012) J Alloy Compd 513:68–74Saji VS, Lee SM, Lee CW (2011) J Korean Electrochem Soc 14:61–70Donglin X, Jangzhuang L, Man X, Xiujian Z (2008) J Non-Cryst Solids 354:1447–1450Araujo J, OrtĂ­z R, LĂłpez-Rivera A, Ortega JM, Montilla M, AlarcĂłn D (2007) J Solid State Electroch 11(Issue 3):407–412Palacios P, Sanchez K, Conesa JC, Fernandez JJ, Wahnon P (2007) Phys Stat Sol A 203:1395–1401Palacios P, Sanchez K, Conesa JC, Wahnon P (2006) Thin Solid Films 515:6280–6284Lee H, Lee J-H, Hwang Y-H, Kim Y (2014) Curr Appl Phys 14:18–22Kim D, Kwon Y, Lee D, Yoon S, Lee S, Yoo B (2015) J Electrochem Soc 162:D36–D41Hou WW, Bob B, Li S, Yang Y (2009) Thin Solid Films 517:6853–6856Lee J, Lee W, Shrestha NK, Lee DY, Lim I, Kang SH, Nah YC, Lee SH, Yi W, Han SH (2014) Mater Chem Phys 144:49–54Yang JY, Lee D, Huh K, Jung SJ, Lee JW, Lee HC, Baek DH, Kim BJ, Kim D, Nam J, Kim GY, Jo W (2015) RSC Adv 5:40719–407257Sall T, Nafidi A, MarĂ­ B, Mollar M, Hartiti B, Fahoume M (2014) J Semicond 35:0630021–0630025Lee JH, Song WC, Yi JS, Joonyang K, Han WD, Hawang J (2003) Thin Solid Films 431-432:349–353Prabukanthan P, Dhanasekaran R (2007) Cryst Growth Des 7:618–623Guillemoles JF, Cowache P, Lusson A, Fezzaa K, Boisivon F, Vedel J, Lincot D (1996) J Appl Phys 79:7293–7302Aguilera I, Palacios P, Wahon P (2010) Sol Energ Mat Sol C 94:1903–1906Palacios P, Aguilera I, WahnĂłn P, Conesa JC (2008) J Phys Chem C 112:9525–952

    Behind film performance in China’s changing institutional context:The impact of signals

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    Grounded in signaling theory, this paper investigates the signals reflecting product quality, innovativeness, reputation and cultural background which influence film performance, i.e. film survival (duration on cinema screen) and box office success, in China’s changing institutional context. This market has grown substantially and still possesses potential for further development. However, China’s unique institutional context presents challenges. By examining an expanded range of potential signals, two of which have not previously been examined in the literature, namely imported films and enhanced format film formats such as 3D and IMAX, we develop a conceptual framework and argue that signaling theory needs to be combined with institutional context. Similar to findings for film industries in other countries, we find quality and reputational signals including budget, star power, sequels, and online consumer reviews to be important in China. However, unique results are also revealed. Chinese consumers react to an innovativeness signal in that they are specifically attracted to enhanced format films. Film award nominations and prizes are insignificant reputational signals. Once other signals are taken into account, imported films on average do not perform as well as domestic films. We link these findings to China’s unique institutional setting and offer important implications for management, recognizing the challenges to film companies of competing in an increasingly globalized market. The paper is also of relevance to policymakers given their continued efforts in shaping the development of China’s film industry

    The prevalence of HBV infection in the cohort of IDPs of war against terrorism in Malakand Division of Northern Pakistan

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    <p>Abstract</p> <p>Background</p> <p>Hepatitis B is an important public health problem in the Pakistani population and is the major cause of chronic hepatitis, cirrhosis, fibrosis and hepatocellular carcinoma. High prevalence of HBV infections has been observed especially in areas of low economic status. In spite of effective immunization programs, no significant change has been observed in the epidemiology of HBV in the rural areas of Pakistan (~67.5% of the total population) mainly due to lack of interest from government authorities and poor hygienic measures. The current study was aimed at estimating the prevalence and risk factors associated with HBV infection within internally displaced persons (IDPs) due to war against terrorism in the Malakand Division of Northern Pakistan.</p> <p>Methods</p> <p>Blood samples from 950 IDPs suspected with HBV infection (including both males and females) were collected and processed with commercial ELISA kits for HBsAg, Anti HBs, HBeAg, Anti HBe antibodies. The samples positive by ELISA were confirmed for HBV DNA by real-time PCR analysis.</p> <p>Results</p> <p>The overall prevalence of HBV observed was 21.05% of which 78.5% were males and 21.5% were females. Most confirmed HBV patients belong to the Malakand and Dir (lower) district. High-risk of infection was found in the older subjects 29.13% (46-60 years), while a lower incidence (11.97%) was observed in children aged <15 years. Lack of awareness, socioecomic conditions, sexual activities and sharing of razor blades, syringes and tattooing needles were the most common risk factors of HBV infection observed during the cohort of patients.</p> <p>Conclusion</p> <p>The present study, revealed for the first time a high degree of prevalence of HBV infection in rural areas of Northern Pakistan. The noticed prevalence is gender- and age-dependent that might be due to their high exposures to the common risk factors. To avoid the transmission of HBV infection proper awareness about the possible risk factors and extension of immunization to the rural areas are recommended.</p

    Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: Environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

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    We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 ??C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.ope

    Autoimmune and autoinflammatory mechanisms in uveitis

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    The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of Treg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8(+) T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders

    Systematic identification of conserved motif modules in the human genome

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    <p>Abstract</p> <p>Background</p> <p>The identification of motif modules, groups of multiple motifs frequently occurring in DNA sequences, is one of the most important tasks necessary for annotating the human genome. Current approaches to identifying motif modules are often restricted to searches within promoter regions or rely on multiple genome alignments. However, the promoter regions only account for a limited number of locations where transcription factor binding sites can occur, and multiple genome alignments often cannot align binding sites with their true counterparts because of the short and degenerative nature of these transcription factor binding sites.</p> <p>Results</p> <p>To identify motif modules systematically, we developed a computational method for the entire non-coding regions around human genes that does not rely upon the use of multiple genome alignments. First, we selected orthologous DNA blocks approximately 1-kilobase in length based on discontiguous sequence similarity. Next, we scanned the conserved segments in these blocks using known motifs in the TRANSFAC database. Finally, a frequent pattern mining technique was applied to identify motif modules within these blocks. In total, with a false discovery rate cutoff of 0.05, we predicted 3,161,839 motif modules, 90.8% of which are supported by various forms of functional evidence. Compared with experimental data from 14 ChIP-seq experiments, on average, our methods predicted 69.6% of the ChIP-seq peaks with TFBSs of multiple TFs. Our findings also show that many motif modules have distance preference and order preference among the motifs, which further supports the functionality of these predictions.</p> <p>Conclusions</p> <p>Our work provides a large-scale prediction of motif modules in mammals, which will facilitate the understanding of gene regulation in a systematic way.</p

    Tuning fulleride electronic structure and molecular ordering via variable layer index

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    C60 fullerides are uniquely flexible molecular materials that exhibit a rich variety of behavior, including superconductivity and magnetism in bulk compounds, novel electronic and orientational phases in thin films, and quantum transport in a single-C60 transistor. The complexity of fulleride properties stems from the existence of many competing interactions, such as electron-electron correlations, electron-vibration coupling, and intermolecular hopping. The exact role of each interaction is controversial due to the difficulty of experimentally isolating the effects of a single interaction in the intricate fulleride materials. Here we report a unique level of control of the material properties of KxC60 ultra-thin films through well-controlled atomic layer indexing and accurate doping concentrations. Using STM techniques, we observe a series of electronic and structural phase transitions as the fullerides evolve from two-dimensional monolayers to quasi-threedimensional multilayers in the early stages of layer-by-layer growth. These results demonstrate the systematic evolution of fulleride electronic structure and molecular ordering with variable KxC60 film layer index, and shed new light on creating novel molecular structures and devices.Comment: 16 pages, 4 figures, to appear in Nature Material

    Essential versus accessory aspects of cell death: recommendations of the NCCD 2015

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    Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death’ (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death’ (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death

    Microbial Patterns Signaling via Toll-Like Receptors 2 and 5 Contribute to Epithelial Repair, Growth and Survival

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    Epithelial cells (ECs) continuously interact with microorganisms and detect their presence via different pattern-recognition receptors (PRRs) including Toll-like receptors (TLRs). Ligation of epithelial TLRs by pathogens is usually associated with the induction of pro-inflammatory mediators and antimicrobial factors. In this study, using human airway ECs as a model, we found that detection of microbial patterns via epithelial TLRs directly regulates tissue homeostasis. Staphylococcus aureus (S. aureus) and microbial patterns signaling via TLR2 and TLR5 induce a set of non-immune epithelial responses including cell migration, wound repair, proliferation, and survival of primary and cancerous ECs. Using small interfering RNA (siRNA) gene targeting, receptor-tyrosine kinase microarray and inhibition studies, we determined that TLR and the epidermal growth factor receptor (EGFR) mediate the stimulating effect of microbial patterns on epithelial repair. Microbial patterns signaling via Toll-like receptors 2 and 5 contribute to epithelial repair, growth and survival. This effect is independent of hematopoietic and other cells as well as inflammatory cytokines suggesting that epithelia are able to regulate their integrity in an autonomous non-inflammatory manner by sensing microbes directly via TLRs
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