Deformation and Damage in Solder During Fast Cyclic Loading

2003 ◽  
Author(s):  
E. S. Ege ◽  
Y.-L. Shen
Keyword(s):  
Cyclic Loading ◽  
Dominant Role ◽  
Local Phase ◽  
Phase Coarsening ◽  
Numerical Studies ◽  
Lap Shear ◽  
Traditional Argument ◽  
Local Plastic Strain ◽  
The Individual ◽  
Phase Arrangement

Experimental and numerical studies on fast cyclic loading of eutectic tin-lead solder and relevant micromechanical issues are presented. High-frequency twin-lap shear tests on solder joints show cracking inside the solder but often connecting the intruded tips of the intermetallic. Finite element modeling was carried out to study the effect of intermetallic morphology. Without the influence of local phase coarsening, the intrusion of intermetallic into the solder alloy is seen to trigger strain localization which promotes failure. The effect of local phase coarsening was also studied numerically, taking into account the individual phase arrangement. A coarser phase structure always shows a faster accumulation of local plastic strain, leading to early failure. Such results, in agreement with typical thermomechanical fatigue features, cannot be obtained from the traditional argument of strength vs. microstructural size. Modeling of the entire lap-shear specimen was also conducted for the purpose of quantifying the deformation behavior. The exact geometry of solder is found to play a dominant role in affecting the shear response.

scholarly journals Microstructure and mechanical properties of an ultrasonic spot welded aluminum alloy: the effect of welding energy

2021 ◽  
Author(s):  
He Peng ◽  
Daolun Chen ◽  
Xianquan Jiang
Keyword(s):  
Shear Strength ◽  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Crack Growth ◽  
Failure Mode ◽  
Spot Welding ◽  
Energy Levels ◽  
Lap Shear Strength ◽  
Pull Out ◽  
Lap Shear

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW)–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations. Keywords: aluminum alloy; ultrasonic spot welding; EBSD; microstructure; tensile strength; fatigue

scholarly journals RIG-I Plays a Dominant Role in the Induction of Transcriptional Changes in Zika Virus-Infected Cells, which Protect from Virus-Induced Cell Death

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1476 ◽  
Author(s):  
Mirjam Schilling ◽  
Anne Bridgeman ◽  
Nicki Gray ◽  
Jonny Hertzog ◽  
Philip Hublitz ◽  
...  
Keyword(s):  
Cell Death ◽  
Zika Virus ◽  
Dominant Role ◽  
A549 Cells ◽  
Effective Control ◽  
Type I ◽  
Type I Ifn ◽  
Structural Protein ◽  
Induced Apoptosis ◽  
The Individual

The Zika virus (ZIKV) has received much attention due to an alarming increase in cases of neurological disorders including congenital Zika syndrome associated with infection. To date, there is no effective treatment available. An immediate response by the innate immune system is crucial for effective control of the virus. Using CRISPR/Cas9-mediated knockouts in A549 cells, we investigated the individual contributions of the RIG-I-like receptors MDA5 and RIG-I to ZIKV sensing and control of this virus by using a Brazilian ZIKV strain. We show that RIG-I is the main sensor for ZIKV in A549 cells. Surprisingly, we observed that loss of RIG-I and consecutive type I interferon (IFN) production led to virus-induced apoptosis. ZIKV non-structural protein NS5 was reported to interfere with type I IFN receptor signaling. Additionally, we show that ZIKV NS5 inhibits type I IFN induction. Overall, our study highlights the importance of RIG-I-dependent ZIKV sensing for the prevention of virus-induced cell death and shows that NS5 inhibits the production of type I IFN.

scholarly journals An improved shear deformation theory for bending beams with symmetrically varying mechanical properties in the depth direction

2020 ◽  
Vol 231 (10) ◽  
pp. 4381-4395 ◽  
Author(s):  
Krzysztof Magnucki ◽  
Jerzy Lewinski ◽  
Ewa Magnucka-Blandzi
Keyword(s):  
Mechanical Properties ◽  
Shear Deformation ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
The Finite Element Method ◽  
Three Point Bending ◽  
Total Potential ◽  
Depth Direction ◽  
Numerical Studies ◽  
The Individual

Abstract The paper is devoted to simply supported beams under three-point bending. Their mechanical properties symmetrically vary in the depth direction. The individual shear deformation theory for beams of such features is proposed. Based on the principle of stationary total potential energy the differential equations of equilibrium are obtained. The system of the equations is analytically solved, and the shear coefficients and deflections of example beams are calculated. The solution is compared with other analytical results obtained with the use of another deformation function. Moreover, the bending problem of these beams is also numerically studied using the finite element method. Results of analytical and numerical studies are presented in Figures and Tables.

scholarly journals Molecular Simulations of Cyclic Loading Behavior of Carbon Nanotubes Using the Atomistic Finite Element Method

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Jianfeng Wang ◽  
Marte S. Gutierrez
Keyword(s):  
Finite Element Method ◽  
Carbon Nanotubes ◽  
Finite Element ◽  
Cyclic Loading ◽  
Large Strain ◽  
Fatigue Behavior ◽  
Dominant Role ◽  
Molecular Simulations ◽  
Viscoelastic Behavior ◽  
Element Method

The potential applications of carbon nanotubes (CNT) in many engineered bionanomaterials and electromechanical devices have imposed an urgent need on the understanding of the fatigue behavior and mechanism of CNT under cyclic loading conditions. To date, however, very little work has been done in this field. This paper presents the results of a theoretical study on the behavior of CNT subject to cyclic tensile and compressive loads using quasi-static molecular simulations. The Atomistic Finite Element Method (AFEM) has been applied in the study. It is shown that CNT exhibited extreme cyclic loading resistance with yielding strain and strength becoming constant within limited number of loading cycles. Viscoelastic behavior including nonlinear elasticity, hysteresis, preconditioning (stress softening), and large strain have been observed. Chiral symmetry was found to have appreciable effects on the cyclic loading behavior of CNT. Mechanisms of the observed behavior have been revealed by close examination of the intrinsic geometric and mechanical features of tube structure. It was shown that the accumulated residual defect-free morphological deformation was the primary mechanism responsible for the cyclic failure of CNT, while the bond rotating and stretching experienced during loading/unloading played a dominant role on the strength, strain and modulus behavior of CNT.

scholarly journals Eurodelta multi-model simulated and observed PM trends in Europe in the period of 1990–2010

2021 ◽  
Author(s):  
Svetlana Tsyro ◽  
Wenche Aas ◽  
Augustin Colette ◽  
Camilla Andersson ◽  
Bertrand Bessagnet ◽  
...  
Keyword(s):  
Trend Analysis ◽  
Dominant Role ◽  
Monitoring Network ◽  
Monitoring And Evaluation ◽  
Mitigation Measures ◽  
Dominant Factor ◽  
Model Ensemble ◽  
Emission Mitigation ◽  
Pm10 And Pm2.5 ◽  
The Individual

Abstract. The Eurodelta-Trends multi-model experiment, aimed to assess the efficiency of emission mitigation measures in improving air quality in Europe during 1990–2010, was designed to answer a series of questions regarding European pollution trends. i.e. were there significant trends detected by observations? do the models manage to reproduce observed trends? how close is the agreement between the models and how large are the deviations from observations? In this paper, we address these issues with respect to PM pollution. An in-depth trend analysis has been performed for PM10 and PM2.5 for the period of 2000–2010, based on results from six chemical transport models and observational data from the EMEP (Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe) monitoring network. Given harmonization of set up and main input data, the differences in model results should mainly result from differences in the process formulations within the models themselves, and the spread in the models simulated trends could be regarded as an indicator for modelling uncertainty. The model ensemble simulations indicate overall decreasing trends in PM10 and PM2.5, with reduction by between 2 and 6 μg m−3 m−3 (or between 10 and 30 %) from 2000 to 2010. Compared to PM2.5, relative PM10 trends are weaker due to large inter-annual variability of natural coarse PM within the former. The changes in the concentrations of PM individual components are in general consistent with emission reductions. There is a reasonable agreement in PM trends estimated by the individual models, with the inter-model variability below 30–40 % over most of Europe, increasing to 50–60 % in northern and eastern parts of EDT domain. Averaged over measurement sites (26 for PM10 and 13 for PM2.5), the mean ensemble simulated trends are −0.24 and −0.22 μg m−3 year−1 for PM10 and PM2.5, which are somewhat weaker than the observed trends of −0.35 and −0.40 μg m−3 year−1, respectively, partly due to models underestimation of PM concentrations. The correspondence is better in relative PM10 and PM2.5 trends, which are −1.7 and −2.0 % year−1 from the model ensemble and −2.1 and −2.9 % year−1 from the observations, respectively. The observations identify significant trends for PM10 at 56 % of the sites and for PM2.5 at 36 % of the sites, which is somewhat less that the fractions of significant modelled trends. Further, we find somewhat smaller spatial variability of modelled PM trends with respect to the observed ones across Europe and also within individual countries. The strongest decreasing PM trends and the largest number of sites with significant trends is found for the summer season, according to both the model ensemble and observations. The winter PM trends are very weak and mostly insignificant. One important reason for that is the very modest reductions and even increases in the emissions of primary PM from residential heating in winter. It should be kept in mind that all findings regarding modeled versus observed PM trends are limited the regions where the sites are located. The analysis reveals a considerable variability of the role of the individual aerosols in PM10 trends across European countries. The multi-model simulations, supported by available observations, point to decreases in SO4−2 concentrations playing an overall dominant role. Also, we see relatively large contributions of the trends of NH4+ and NO3− to PM10 decreasing trends in Germany, Denmark, Poland and the Po Valley, while the reductions of primary PM emissions appears to be a dominant factor in bringing down PM10 in France, Norway, Portugal, Greece and parts of the UK and Russia. Further discussions are given with respect to emission uncertainties and the effect of inter-annual meteorological variability on the trend analysis.

scholarly journals Host poly(A) polymerases PAPD5 and PAPD7 provide two layers of protection that ensure the integrity and stability of hepatitis B virus RNA

2021 ◽  
Author(s):  
Fei Liu ◽  
Amy C.H Lee ◽  
Fang Guo ◽  
Andrew S. Kondratowicz ◽  
Holly M Micolochick Steuer ◽  
...  
Keyword(s):  
Dominant Role ◽  
Regulatory Element ◽  
Rna Stability ◽  
Antiviral Effect ◽  
Inhibitory Effect ◽  
Stem Loop ◽  
Knock Out ◽  
The Individual

Noncanonical poly(A) polymerases PAPD5 and PAPD7 (PAPD5/7) stabilize HBV RNA via the interaction with the viral post-transcriptional regulatory element (PRE), representing new antiviral targets to control HBV RNA metabolism, HBsAg production and viral replication. Inhibitors targeting these proteins are being developed as antiviral therapies, therefore it is important to understand how PAPD5/7 coordinate to stabilize HBV RNA. Here, we utilized a potent small-molecule AB-452 as a chemical probe, along with genetic analyses to dissect the individual roles of PAPD5/7 in HBV RNA stability. AB-452 inhibits PAPD5/7 enzymatic activities and reduces HBsAg both in vitro (EC50 ranged from 1.4 to 6.8 nM) and in vivo by 0.93 log10. Our genetic studies demonstrate that the stem-loop alpha sequence within PRE is essential for both maintaining HBV poly(A) tail integrity and determining sensitivity towards the inhibitory effect of AB-452. Although neither single knock-out (KO) of PAPD5 nor PAPD7 reduces HBsAg RNA and protein production, PAPD5 KO does impair poly(A) tail integrity and confers partial resistance to AB-452. In contrast, PAPD7 KO could not result in any measurable phenotypic changes, but displays a similar antiviral effect as AB-452 treatment when PAPD5 is depleted simultaneously. PAPD5/7 double KO confers complete resistance to AB-452 treatment. Our results thus indicate that PAPD5 plays a dominant role in stabilizing viral RNA by protecting the integrity of its poly(A) tail, while PAPD7 serves as a second line of protection. These findings inform PAPD5 targeted therapeutic strategies and open avenues for further investigating PAPD5/7 in HBV replication.

scholarly journals Representations of queer identity in David Lynch's film Mulholland Drive

2021 ◽  
pp. 87-92
Author(s):  
Alena Molodina
Keyword(s):  
Cultural Studies ◽  
Queer Theory ◽  
Social Order ◽  
Dominant Role ◽  
Interdisciplinary Approach ◽  
Psychological State ◽  
David Lynch ◽  
Queer Identity ◽  
The Individual ◽  
Mulholland Drive

The purpose of the article. This essay considers the queer identity as a modern tragic figure through a reading of David Lynch's 2001 film Mulholland Drive. Methodology. The article uses a comprehensive interdisciplinary approach using the methodological tools of cultural studies and queer theory based on structural-functional, semiotic-hermeneutic analysis, as well as Lacan's psychoanalytic concept of the subject. The scientific novelty. Within the framework of the humanities, in particular cultural studies, the analysis of the film by David Lynch "Mulholland Drive" in the context of queer theory is carried out for the first time. Conclusions. Since cinematography is a synthesis of various types of art, it embodies cultural phenomena and reproduces realities of life. Analysis of the peculiarities of the representation of queer identity in David Lynch's film Mulholland Drive through the prism of queer theory, in which identity is nothing more than a phenomenon that forms under the pressure of the dominant discourse and social order gives it the status of a cultural illusion or myth, demonstrates existing ideals. Cinema in the context of queer theory is self-reflective, autocratic, not indifferent. It can create a safe space - and at the same time be a protest action. The means by which the representation of a queer identity takes the place can be traced at all symbolic levels (material, index, iconic). At the material level, the grand plan is used as a sign in which all the characters in the film are related, without separating homosexual women visually. At the level of index status, the creation of the image of a homosexual couple is due to their profession. The heroines belong to the creative environment, in their relationship the dominant role is played by Diane. At the iconic level, images are constructed through their relationship with society. The heroines experience internal contradictions between their psychological state, natural nature, and social norms. The sexuality that is represented in the film contains a confrontation between the individual and the social. There is a tendency to normalize the image of queer identity in cinema, due to changes in the public consciousness. Based on the analysis, it was found that the film David Lynch reflects homosexuality as such, and not in the canonical models of traditional relationships.

An Enhanced Interface Model for Friction Fatigue Problems of Axially Loaded Piles

2019 ◽  
Author(s):  
Borana Kullolli ◽  
Matthias Baeßler ◽  
Pablo Cuéllar ◽  
Shilton Rica ◽  
Frank Rackwitz
Keyword(s):  
Cyclic Loading ◽  
Dominant Role ◽  
Normal Pressure ◽  
Interface Model ◽  
Structural Behaviour ◽  
Confining Stress ◽  
Cyclic Mobility ◽  
Axially Loaded ◽  
Bulk Model ◽  
Axially Loaded Piles

Abstract The shaft bearing capacity often plays a dominant role for the overall structural behaviour of axially loaded piles in offshore deep foundations. Under cyclic loading, a narrow zone of soil at the pile-soil interface is subject to cyclic shearing solicitations. Thereby, the soil may densify and lead to a decrease of confining stress around the pile due to micro-phenomena such as particle crushing, migration and rearrangement. This reduction of radial stress has a direct impact on the shaft capacity, potentially leading in extreme cases to pile failure. An adequate interface model is needed in order to model this behaviour numerically. Different authors have proposed models that take typical interface phenomena in account such as densification, grain breakage, normal pressure effect and roughness. However, as the models become more complex, a great number of material parameters need to be defined and calibrated. This paper proposes the adoption and transformation of an existing soil bulk model (Pastor-Zienkiewicz) into an interface model. To calibrate the new interface model, the results of an experimental campaign with the ring shear device under cyclic loading conditions are here presented. The constitutive model shows a good capability to reproduce typical features of sand behaviour such as cyclic compaction and dilatancy, which in saturated partially-drained conditions may lead to liquefaction and cyclic mobility phenomena.

miR34s in Normal and Malignant B-Cells: miR34A Plays a Dominant Role in Normal B-Cells, and aggressive Diffuse Large B-Cell Lymphoma Carry Combined Lesions of TP53, MIR34A, and MIR34B/C

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 296-296 ◽  
Author(s):  
Christoffer Hother ◽  
Fazila Asmar ◽  
Gorjan Kulosman ◽  
Marianne B. Treppendahl ◽  
Ditte Reker ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cells ◽  
Lymph Nodes ◽  
Tp53 Mutation ◽  
Dominant Role ◽  
B Cell Lymphoma ◽  
Tp53 Mutations ◽  
Promoter Dna Methylation ◽  
Promoter Dna ◽  
The Individual

Abstract Abstract 296 Background: In diffuse large B-cell lymphoma (DLBCL), a number of studies have shown that dual disruption of the p16/Rb and the ARF/p53 pathway, e.g. deletion of the INK4A/ARF locus, are negative prognostic factors for survival. Molecular studies have shown that the p53-miR34 axis may be another link between the ARF/p53 pathway and the p16/Rb pathway. In a complex circuit, p53 promotes transcription of MIR34A and MIR34B/C, and the miR34s' in turn act as mediators of p53 signaling. In addition, miR34s' have been shown to inhibit MYC and several proto-oncogens that counteract the p16/Rb tumor suppressor pathway. These observations place the miR34s' at the center of cell cycle and apoptosis regulation, and loss of miR34 expression has been associated with adverse response to therapy in several tumor types. In CLL it has been suggested that miR34A expression is a surrogate marker for TP53 disruption and the MDM2 SNP309 GG genotype, both associated with a poor prognosis. Design and methods: In CD19+ B-cells isolated from healthy donors (PBL-B) and reactive lymph nodes, the expression of the –5p and –3p species of miR34A, miR34B, and miR34C was analysed by qRT-PCR using LNA-based primers from Exiqon that discriminate the individual miR34 members. Histone H3K4 and H3K27 methylation status at the MIR34A and MIR34B/C promoters was analyzed by ChIP. In 120 newly diagnosed DLBCLs we studied the combined status of TP53 mutations, MIR34A and MIR34B/C promoter DNA methylation, and the MDM2SNP309 GG genotype using a panel of PCR based methods. Results: We initially determined the expression of the individual miR34 family members in PBL-B and in reactive lymph nodes. While miR34A-5p was expressed at low levels in normal PBL-B, no expression of miR34A-3p, miR34B-5p, miR34B-3p, miR34C-5p, and miR34C-3p was observed. In reactive lymph nodes the expression of miR34A-5p was induced in average 70 fold (P<0.001), while no significant induction was observed for the rest of the investigated miRs, including the homologous miR34B-5p and miR34C-5p. No promoter DNA methylation was observed in PBL-B, but ChIP experiments showed a relative enrichment for the bivalent H3K4me3/H3K27me3 silencing mark at the MIR34B/C promoter. In 100 of the 120 (83%) DLBCLs one or more of the investigated genes carried (epi)-genomic alterations including TP53 mutations: 20(17%), MIR34A methylation: 34(28%), MIR34B/C methylation: 93(78%) and the MDM2 SNP309 GG-genotype 11(9%). All but one of the MIR34A methylated cases also had methylation of MIR34B/C. Seven cases carried combined TP53 mutation and methylation of both MIR34A and MIR34B/C. A borderline inferior overall survival for patients carrying TP53 mutations was found (p=0.058), while none of the other parameters influenced survival. However, the 7 cases with concomitant mutation of TP53 and methylation of both MIR34A and MIR34 B/C had a median survival of 14 months (p=0.02). In a DLBCL-cell line with concomitant TP53 mutation and methylation of both MIR34A and MIR34B/C, miR34s' were upregulated by 5-aza-2'deoxycytidine (5-aza-CdR). Conclusions: In normal B-cells miR34A seems to play a dominant role over miR34B/C, however in DLBCL the concomitant DNA methylation of MIR34B/C in the MIR34A methylated cases suggest they may compensate for each other. Our results suggest that in DLBCL the p53-miR34 axis is not linear, and that the TP53, MIR34A and MIR34B/C “triple-hit” DLBCLs may represent more aggressive lymphomas that may benefit from treatment with 5-aza-CdR. This is, to the best of our knowledge, the first study to address these issues in a large sample of diagnostic DLBCL cases. Disclosures: No relevant conflicts of interest to declare.

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