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  • 1
    Article
    Article
    Non-Abelian Bloch oscillations in higher-order topological insulators
    2020
    Details
    Language: English
    In: Nature communications, 2020-11-23, Vol.11 (1), p.5942-5942
    Description: Bloch oscillations (BOs) are a fundamental phenomenon by which a wave packet undergoes a periodic motion in a lattice when subjected to a force. Observed in a wide range of synthetic systems, BOs are intrinsically related to geometric and topological properties of the underlying band structure. This has established BOs as a prominent tool for the detection of Berry-phase effects, including those described by non-Abelian gauge fields. In this work, we unveil a unique topological effect that manifests in the BOs of higher-order topological insulators through the interplay of non-Abelian Berry curvature and quantized Wilson loops. It is characterized by an oscillating Hall drift synchronized with a topologically-protected inter-band beating and a multiplied Bloch period. We elucidate that the origin of this synchronization mechanism relies on the periodic quantum dynamics of Wannier centers. Our work paves the way to the experimental detection of non-Abelian topological properties through the measurement of Berry phases and center-of-mass displacements. Bloch oscillations (BO) are intrinsically related to the geometry and topological properties of the underlying band structure. Here, Di Liberto et al. predict a unique topological effect manifested in the BOs of higher-order topological insulators through the interplay of non-Abelian Berry curvature and quantized Wilson loops.
    Subject(s): Index Medicus ; Topological insulators ; Ultracold gases
    E-ISSN: 2041-1723
    DOI: 10.1038/s41467-020-19518-x
    Source: Nature Open Access
    Source: PubMed Central
    Source: Directory of Open Access Journals
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 2
    Article
    Article
    Design of custom cranial prostheses combining manufacturing and drop test finite element simulations
    2020
    ISSN: 0268-3768 
    Details
    Language: English
    In: International journal of advanced manufacturing technology, 2020-11-01, Vol.111 (5-6), p.1627-1641
    Description: In this work, impact puncture tests (drop tests) have been used to both tune numerical models and correlate the performance of customised titanium cranial prostheses to the manufacturing process. In fact, experimental drop tests were carried out either on flat disk-shaped samples or on prototypes of titanium cranial prostheses (Ti-Gr5 and Ti-Gr23 were used) fabricated via two innovative sheet metal forming processes (the super plastic forming (SPF) and the single point incremental forming (SPIF)). Results from drop tests on flat disk-shaped samples were used to define the material behaviour of the two investigated alloys in the finite element (FE) model, whereas drop tests on cranial prostheses for validation purposes. Two different approaches were applied and compared for the FE simulation of the drop test: (i) assuming a constant thickness (equal to the one of the undeformed blank) or (ii) importing the thickness distribution determined by the sheet forming processes. The FE model of the drop test was used to numerically evaluate the effect of the manufacturing process parameters on the impact performance of the prostheses: SPF simulations were run changing the strain rate and the tool configuration, whereas SPIF simulations were run changing the initial thickness of the sheet and the forming strategy. The comparison between numerical and experimental data revealed that the performance in terms of impact response of the prostheses strongly depends on its thickness distribution, being strain hardening phenomena absent due to the working conditions adopted for the SPF process or to the annealing treatment conducted after the SPIF process. The manufacturing parameters/routes, able to affect the thickness distribution, can be thus effectively related to the mechanical performance of the prosthesis determined through impact puncture tests.
    Subject(s): Prostheses ; Model testing ; Impact response ; Metal sheets ; Mechanical properties ; Impact tests ; Finite element method ; Forming techniques ; Thickness ; Alloying elements ; Metal forming ; Simulation ; Drop tests ; Process parameters ; Titanium ; Mathematical models ; Manufacturing ; Numerical models ; Strain hardening ; Strain rate
    ISSN: 0268-3768
    E-ISSN: 1433-3015
    DOI: 10.1007/s00170-020-06213-w
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 3
    Article
    Article
    Prediction of the residual state of stress in a superduplex stainless steel produced by sand casting (using a coupled thermo-mechanical approach)
    2020
    ISSN: 0268-3768 
    Details
    Language: English
    In: International journal of advanced manufacturing technology, 2020-04-01, Vol.107 (7-8), p.3011-3022
    Description: The present work aims at investigating the effect, in terms of residual stress prediction, determined by the adoption of different material constitutive models in the Finite Element simulation of the casting process of a superduplex stainless steel benchmark, from the cooling after the pouring phase to the subsequent heat treatment (heating and water quenching). A 3D thermo-mechanical Finite Element (FE) model was created with the commercial code Abaqus: the preliminary thermal problem, i.e. the determination of the heat transfer coefficients during both the mould cooling and the quenching, was solved by means of an inverse analysis approach by minimizing the difference between the numerical evolution of temperature and the experimental acquisition coming from real casting test. Two separate routes were followed according to the adopted constitutive equations: modelling the material as (i) elasto-plastic or (ii) elasto-viscoplastic. The numerical prediction of the residual state of stress in terms of casting relaxation was compared with the experimental data after the cut of the casting using an electro-discharge machine. The analysis revealed that when the elasto-viscoplastic modelling was adopted, the simulations underestimated the relaxation with an error larger than 50%; on the other hand, the elasto-plastic model leads to an overestimation with an error of about 30%.
    Subject(s): Heat treatment ; Constitutive relationships ; Iron and steel making ; Cooling ; Computer simulation ; Water quenching ; Casting machines ; Sand casting ; Stainless steels ; Finite element method ; Stress relaxation ; Stainless steel ; Constitutive models ; Mathematical models ; Numerical prediction ; Heat transfer coefficients ; Three dimensional models ; Constitutive equations ; Residual stress
    ISSN: 0268-3768
    E-ISSN: 1433-3015
    DOI: 10.1007/s00170-020-05213-0
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 4
    Article
    Article
    Numerical–experimental investigations on the manufacturing of an aluminium bipolar plate for proton exchange membrane fuel cells by warm hydroforming
    2013
    ISSN: 0268-3768 
    Details
    Language: English
    In: International journal of advanced manufacturing technology, 2013-10-01, Vol.69 (1-4), p.731-742
    Description: This research study focuses on the manufacturing of a bipolar plate used in proton exchange membrane fuel cells. In particular, the authors investigate the manufacturing of the part by means of warm hydroforming, adopting an aluminium alloy (AA6061) as sheet material. Both the channel profile (the reagent channel width and the die upper radius), and the bipolar plate geometries (in terms of channel layouts) are investigated by means of finite element simulations. Preliminary experimental investigations were carried out in order to define both the mechanical (flow curves) and strain behaviours (forming limit curves) of the adopted aluminium alloy according to temperature and strain rate. Subsequent finite element investigations aimed to define the channel profile by means of 2D models: a statistical approach was used to evaluate the dimension of the reagent channel width, the die upper radius and the sheet thickness. Finally, proposed bipolar plate geometries were investigated by running 3D simulations at different working temperatures and oil pressures in order to evaluate: (1) the bipolar plate geometry able to avoid regions with critical thinning and (2) suitable parameters for the warm hydroforming process.
    Subject(s): Fuel cell industry ; Aluminum alloys ; Fuel cells ; Aluminum base alloys ; Computer simulation ; Two dimensional models ; Automobiles ; Finite element method ; Hydroforming ; Sheet material ; Reagents ; Forming limit diagrams ; Manufacturing ; Proton exchange membrane fuel cells ; Strain rate
    ISSN: 0268-3768
    E-ISSN: 1433-3015
    DOI: 10.1007/s00170-013-5047-1
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 5
    Article
    Article
    Experimental investigation of the mechanical performances of titanium cranial prostheses manufactured by super plastic forming and single-point incremental forming
    2018
    ISSN: 0268-3768 
    Details
    Language: English
    In: International journal of advanced manufacturing technology, 2018-09, Vol.98 (5), p.1489-1503
    Description: In the present work, sheet-forming processes, i.e. super plastic forming and single-point incremental forming, have been adopted for the manufacturing of custom prostheses, instead of subtractive and additive techniques that are time- and cost-consuming for a single-piece production. Regarding concerns of the material, three different titanium alloys were used: pure titanium and two grades of the alloy Ti-6Al-4V (the standard one and the extra low interstitial one). Since no standard protocol exists to assess the mechanical performance of cranial implants, an experimental procedure has been designed and used in this work for producing polymethylmethacrylate supports, on which the cranial prostheses were firmly connected and subjected to impact puncture tests (drop tests). An experimental campaign could thus be conducted to investigate the effect on the mechanical response of (a) the titanium alloy, (b) the initial blank thickness and (c) the manufacturing process. Drop tests, carried out according to the proposed procedure, have shown no failure of the prostheses, neither in the area of the impact nor in the anchoring region and have revealed that, irrespective of the adopted manufacturing process, which does not alter the material, the amount of energy absorbed by the implants is always larger than 70%.
    Subject(s): Media Management ; Engineering ; Ti-6Al-4V ; Industrial and Production Engineering ; Computer-Aided Engineering (CAD, CAE) and Design ; SPF ; Pure titanium ; Ti-6Al-4V-ELI ; Mechanical Engineering ; SPIF ; Drop test ; Titanium alloys ; Advertising campaigns ; Polymethylmethacrylate ; Titanium industry ; Implants, Artificial ; Prosthesis ; Prostheses ; Surgical implants ; Drop tests ; Mechanical properties ; Forming ; Impact tests ; Titanium base alloys ; Anchoring ; Mechanical analysis ; Forming techniques ; Manufacturing
    ISSN: 0268-3768
    E-ISSN: 1433-3015
    DOI: 10.1007/s00170-018-2338-6
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 6
    Article
    Article
    High-density neutrophils in MGUS and multiple myeloma are dysfunctional and immune-suppressive due to increased STAT3 downstream signaling
    2020
    ISSN: 2045-2322 
    Details
    Language: English
    In: Scientific reports, 2020-02-06, Vol.10 (1), p.1983-1983
    Description: To understand neutrophil impairment in the progression from MGUS through active MM, we investigated the function of mature, high-density neutrophils (HDNs), isolated from peripheral blood. In 7 MM, 3 MGUS and 3 healthy subjects by gene expression profile, we identified a total of 551 upregulated and 343 downregulated genes in MM-HDN, involved in chemokine signaling pathway and FC-gamma receptor mediated phagocytosis conveying in the activation of STAT proteins. In a series of 60 newly diagnosed MM and 30 MGUS patients, by flow-cytometry we found that HDN from MM, and to a lesser extend MGUS, had an up-regulation of the inducible FcγRI (also known as CD64) and a down-regulation of the constitutive FcγRIIIa (also known as CD16) together with a reduced phagocytic activity and oxidative burst, associated to increased immune-suppression that could be reverted by arginase inhibitors in co-culture with lymphocytes. In 43 consecutive newly-diagnosed MM patients, who received first-line treatment based on bortezomib, thalidomide and dexamethasone, high CD64 could identify at diagnosis patients with inferior median overall survival (39.5 versus 86.7 months, p = 0.04). Thus, HDNs are significantly different among healthy, MGUS and MM subjects. In both MGUS and MM neutrophils may play a role in supporting both the increased susceptibility to infection and the immunological dysfunction that leads to tumor progression.
    Subject(s): Monoclonal Gammopathy of Undetermined Significance - drug therapy ; Follow-Up Studies ; Monoclonal Gammopathy of Undetermined Significance - genetics ; Tumor Escape - genetics ; Multiple Myeloma - mortality ; Humans ; Middle Aged ; Male ; Multiple Myeloma - immunology ; Gene Expression Profiling ; Phagocytosis - genetics ; Case-Control Studies ; Signal Transduction - immunology ; Multiple Myeloma - drug therapy ; Disease Susceptibility - immunology ; Female ; Neutrophils - metabolism ; STAT3 Transcription Factor - metabolism ; Monoclonal Gammopathy of Undetermined Significance - mortality ; Kaplan-Meier Estimate ; Neutrophils - immunology ; Phagocytosis - immunology ; Gene Expression Regulation, Neoplastic - immunology ; Signal Transduction - genetics ; Disease Progression ; Monoclonal Gammopathy of Undetermined Significance - immunology ; Antineoplastic Combined Chemotherapy Protocols - therapeutic use ; Aged ; Multiple Myeloma - genetics ; Bortezomib ; Dexamethasone ; Neutrophils ; Stat3 protein ; Multiple myeloma ; Arginase ; Leukocytes (neutrophilic) ; Gene expression ; Phagocytes ; Signal transduction ; Cytometry ; CD16 antigen ; Lymphocytes ; Down-regulation ; Peripheral blood ; Thalidomide ; Phagocytosis ; Index Medicus
    ISSN: 2045-2322
    E-ISSN: 2045-2322
    DOI: 10.1038/s41598-020-58859-x
    Source: Nature Open Access
    Source: Academic Search Ultimate
    Source: PubMed Central
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  • 7
    Article
    Article
    Magnetic domain structure in nanocrystalline nickel electrodeposits
    2018
    ISSN: 0021-8979 
    Details
    Language: English
    In: Journal of applied physics, 2018-06-21, Vol.123 (23), p.234301
    Description: The correlation between the crystal/defect and the magnetic domain structure of nanocrystalline (nc) bulk nickel produced by electrodeposition was investigated. By means of conventional and high resolution transmission electron microscopy, an average grain size of 23 nm was determined; nano-grains surrounded by low angle and high angle boundaries and the presence of nanotwins and stacking faults were observed. The nc nickel exhibited soft magnetic properties. Lorentz TEM (LTEM) in the Fresnel mode revealed magnetic domains of various sizes in the micrometer range extending over many grains, with a few random pinning sites, exhibiting a magnetic ripple structure and vortices. The LTEM was used to investigate the motion of domain walls driven by an external in situ magnetic field and to determine the domain wall width. Domain wall movement was observed at very small magnetic fields along the hysteresis loop. The correlation of the grain size and magnetic properties shows good agreement with the Herzer random anisotropy model for nanocrystalline materials, although the nc nickel studied here has no traces of an amorphous phase.
    ISSN: 0021-8979
    E-ISSN: 1089-7550
    DOI: 10.1063/1.5024004
    Source: American Institute of Physics (AIP) Publications
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  • 8
    Article
    Article
    Jet and Accretion-Disk Emission Untangled in 3C 273
    2004
    ISSN: 0036-8075 
    Details
    Language: English
    In: Science (American Association for the Advancement of Science), 2004-11-05, Vol.306 (5698), p.998-1002
    Description: A long-term spectral variability study of 3C 273 on data obtained by BeppoSAX allows us to decouple the beamed nonthermal (jet) and unbeamed thermal (accretion flow) radiation produced in the inner region of a radio-loud active galactic nucleus. Jet power, when compared with unbeamed radiation, increases with energy. The thermal component is generally overwhelmed by the nonthermal radiation, by a factor of 1.2 to 3 in the 2- to 10-keV range and up to a factor of 7 above 20 keV. In only one case, the accretion flow overcomes the jet, allowing the K iron line to emerge clearly over the continuum.
    Subject(s): Material films ; Power laws ; Thermal radiation ; Ultraviolet reflection ; X ray spectrum ; Reports ; Photons ; Spectral index ; Line spectra ; Energy transfer ; Power lines ; Quasars ; Earth, ocean, space ; Stellar systems. Galactic and extragalactic objects and systems. The universe ; Quasars. Active or peculiar galaxies, objects, and systems ; Astronomy ; Exact sciences and technology ; Galaxies ; Space sciences ; Research
    ISSN: 0036-8075
    E-ISSN: 1095-9203
    DOI: 10.1126/science.1101787
    Source: Single Journals
    Source: Academic Search Ultimate
    Source: EBSCOhost EJS
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
    URL: http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=16268252$$DView record in Pascal Francis
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  • 9
    Article
    Article
    A low-voltage low-power voltage reference based on subthreshold MOSFETs
    2003
    ISSN: 0018-9200 
    Details
    Language: English
    In: IEEE journal of solid-state circuits, 2003-01, Vol.38 (1), p.151-154
    Description: In this work, a new low-voltage low-power CMOS voltage reference independent of temperature is presented. It is based on subthreshold MOSFETs and on compensating a PTAT-based variable with the gate-source voltage of a subthreshold MOSFET. The circuit, designed with a standard 1.2-/spl mu/m CMOS technology, exhibits an average voltage of about 295 mV with an average temperature coefficient of 119 ppm//spl deg/C in the range -25 to +125/spl deg/C. A brief study of gate-source voltage behavior with respect to temperature in subthreshold MOSFETs is also reported.
    Subject(s): Integrated circuit technology ; Low voltage ; Temperature distribution ; CMOS analog integrated circuits ; Doping ; CMOS technology ; Capacitance ; Threshold voltage ; Permittivity ; MOSFETs
    ISSN: 0018-9200
    E-ISSN: 1558-173X
    DOI: 10.1109/JSSC.2002.806266
    Source: IEEE Electronic Library (IEL)
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  • 10
    Article
    Article
    Prevalence of maternal antenatal anxiety and its association with demographic and socioeconomic factors: A multicentre study in Italy
    2020
    ISSN: 0924-9338 
    Details
    Language: English
    In: European psychiatry, 2020-09-07, Vol.63 (1), p.e84-16
    Description: Maternal antenatal anxiety is very common, and despite its short- and long-term effects on both mothers and fetus outcomes, it has received less attention than it deserves in scientific research and clinical practice. Therefore, we aimed to estimate the prevalence of state anxiety in the antenatal period, and to analyze its association with demographic and socioeconomic factors. A total of 1142 pregnant women from nine Italian healthcare centers were assessed through the state scale of the State-Trait Anxiety Inventory and a clinical interview. Demographic and socioeconomic factors were also measured. The prevalence of anxiety was 24.3% among pregnant women. There was a significantly higher risk of anxiety in pregnant women with low level of education (p 〈 0.01), who are jobless (p 〈 0.01), and who have economic problems (p 〈 0.01). Furthermore, pregnant women experience higher level of anxiety when they have not planned the pregnancy (p 〈 0.01), have a history of abortion (p 〈 0.05), and have children living at the time of the current pregnancy (p 〈 0.05). There exists a significant association between maternal antenatal anxiety and economic conditions. Early evaluation of socioeconomic status of pregnant women and their families in order to identify disadvantaged situations might reduce the prevalence of antenatal anxiety and its direct and indirect costs.
    Subject(s): Prevalence ; Pregnant Women - psychology ; Humans ; Social Class ; Socioeconomic Factors ; Mothers - psychology ; Pregnancy ; Young Adult ; Adolescent ; Anxiety - epidemiology ; Adult ; Female ; Italy - epidemiology ; Pregnancy Complications - epidemiology ; Intervention ; Performance evaluation ; Statistical analysis ; Gynecology ; Mental health ; Families & family life ; Midwifery ; Mental depression ; Psychologists ; Obstetrics ; Mothers ; Variables ; Observatories ; Hospitals ; Womens health ; Anxieties ; Socioeconomic factors ; Questionnaires ; Clinical psychology ; Index Medicus ; socioeconomic factors ; Demographic factors ; screening ; maternal antenatal anxiety
    ISSN: 0924-9338
    E-ISSN: 1778-3585
    DOI: 10.1192/j.eurpsy.2020.82
    Source: PubMed Central
    Source: Directory of Open Access Journals
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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