1,434 research outputs found

    Influence of limestone filler and of the size of the aggregates on DEF

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    This experimental study aims to determine the effect of limestone filler on concrete expansion due to delayed ettringite formation (DEF). Different mortars made with different sizes and percentages of limestone filler and Portland cement CEM I 52.5N are conserved in water. The expansion of the specimens is measured. Results show that DEF is not inhibited by limestone filler. The kinetics and the amplitude of the swelling depend on the size of the limestone filler. The volume fraction of aggregates changes only the kinetics: the relation between swelling and water uptake depends only on the size of the aggregates.Comment: 16 pages, 9 figures, 4 table

    Elastic and magnetic effects on the infrared phonon spectra of MnF2

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    We measured the temperature dependent infrared reflectivity spectra of MnF2 between 4 K and room temperature. We show that the phonon spectrum undergoes a strong renormalization at TN. The ab-initio calculation we performed on this compound accurately predict the magnitude and the direction of the phonon parameters changes across the antiferromagnetic transition, showing that they are mainly induced by the magnetic order. In this material, we found that the dielectric constant is mostly from phonon origin. The large change in the lattice parameters with temperature seen by X-ray diffraction as well as the A2u phonon softening below TN indicate that magnetic order induced distortions in MnF2 are compatible with the ferroelectric instabilities observed in TiO2, FeF2 and other rutile-type fluorides. This study also shows the anomalous temperature evolution of the lower energy Eu mode in the paramagnetic phase, which can be compared to that of the B1g one seen by Raman spectroscopy in many isostructural materials. This was interpreted as being a precursor of a phase transition from rutile to CaCl2 structure which was observed under pressure in ZnF2.Comment: 8 pages, 8 figures, updated version accepted in PR

    Quantum criticality at cryogenic melting of polar bubble lattices

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    Quantum fluctuations (QFs) caused by zero-point phonon vibrations (ZPPVs) are known to prevent the occurrence of polar phases in bulk incipient ferroelectrics down to 0K1-3. On the other hand, little is known about the effects of QFs on the recently discovered topological patterns in ferroelectric nanostructures4-9. Here, by using an atomistic effective Hamiltonian within classical Monte Carlo (CMC) and path integral quantum Monte Carlo (PI-QMC)1,3,10,11, we unveil how QFs affect the topology of several dipolar phases in ultrathin Pb(Zr0.4Ti0.6)O3 (PZT) films. In particular, our PI-QMC simulations show that the ZPPVs do not suppress polar patterns but rather stabilize the labyrinth4, bimeron5 and bubble phases12,13 within a wider range of bias field magnitudes. Moreover, we reveal that quantum fluctuations induce a quantum critical point (QCP) separating a hexagonal bubble lattice from a liquid-like state characterized by spontaneous motion, creation and annihilation of polar bubbles at cryogenic temperatures. Finally, we show that the discovered quantum melting is associated with anomalous physical response, as, e.g., demonstrated by a negative longitudinal piezoelectric coefficient.Comment: Nature communication, accepted, 21 pages, 4 Fig

    Giant electrocaloric response in the prototypical Pb(Mg,Nb)O3_{3} relaxor ferroelectric from atomistic simulations

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    An atomistic effective Hamiltonian is used to investigate electrocaloric (EC) effects of Pb(Mg1/3_{1/3}Nb2/3_{2/3})O3_{3} (PMN) relaxor ferroelectrics in its ergodic regime, and subject to electric fields applied along the pseudocubic [111] direction. Such Hamiltonian qualitatively reproduces (i) the electric field-versus-temperature phase diagram, including the existence of a critical point where first-order and second-order transitions meet each other; and (ii) a giant EC response near such critical point. It also reveals that such giant response around this critical point is microscopically induced by field-induced percolation of polar nanoregions. Moreover, it is also found that, for any temperature above the critical point, the EC coefficient-versus-electric field curve adopts a maximum (and thus larger electrocaloric response too), that can be well described by the general Landau-like model proposed in [Jiang et al, Phys. Rev. B 96, 014114 (2017)] and that is further correlated with specific microscopic features related to dipoles lying along different rhombohedral directions. Furthermore, for temperatures being at least 40 K higher than the critical temperature, the (electric field, temperature) line associated with this maximal EC coefficient is below both the Widom line and the line representing percolation of polar nanoregions.Comment: 6 pages, 5 figure

    PENINGKATAN KECAKAPAN MASYARAKAT SONAF HONIS BONEN DALAM BUDIDAYA DAN PENGOLAHAN CABAI

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    Ketersediaan buah cabai di pasaran umumnya tidak stabil. Saat panen raya suplai cabai melimpah sehingga harganya rendah. Sebaliknya saat musim hujan, suplai cabai sangat terbatas sehingga harganya melonjak. Masyarakat desa Oeltua Kabupaten Kupang umumnya adalah petani dan peternak. Salah satu tanaman yang banyak diusahakan adalah cabai. Melalui kegiatan PKM ini dilakukan transfer ilmu pengetahuan dan keterampilan bagi Kelompok Tani Kaum Ibu Sonaf Honis Bonen dan masyarakat setempat untuk meningkatkan kecakapan dalam budidaya cabai serta pengolahan cabai, yaitu dengan pemanfaatan mulsa plastik hitam perak serta penggunaan food dehydrator dalam pengolahan buah cabai. Kegiatan dilakukan dengan metode penyuluhan dan diskusi serta demplot penggunaan mulsa plastik dalam budidaya cabai, serta praktek pengolahan buah cabai menggunakan food dehydrator. Mulsa plastik berguna untuk mencegah pertumbuhan gulma serta mengurangi evaporasi. Hal ini sesuai untuk Kabupaten Kupang yang termasuk daerah semi arid atau beriklim kering. Proses pengeringan buah cabai cukup sederhana sehingga mudah dipraktekkan oleh peserta kegiatan ini. Luaran kegiatan PKM ini berupa produk buah cabai kering, boncabai, serta serpihan cabai atau chilli-flake. Luaran akademik berupa publikasi ilmiah pada jurnal nasional terindeks Sinta-5, publikasi pada media lokal online serta visdeo kegiatan yang diunggah pada web-Fakultas Pertanian Undana

    Donepezil Effects on Mood in Patients with Schizophrenia and Schizoaffective Disorder

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    Donepezil, 5 mg/d for 6 wk then 10 mg/d for 6 wk, and placebo daily for 12 wk in a double-blind cross-over paradigm, was added to the therapeutic regimen of 13 patients with schizophrenia or schizoaffective disorders, clinically stable on atypical antipsychotic medications. Patients had varying degrees of depressive symptoms, ranging from no depression to clinically significant depression. There was no worsening or induction of depression in individual patients or the group as a whole. In addition there was a statistically significant antidepressant effect in the group as a whole during the donepezil condition and a clinically significant antidepressant effect in the patients with clinically significant depressive symptoms, although there were not enough depressed patients in the group to conclude that donepezil may have antidepressant effects. Thus, in this study, donepezil did not induce or worsen depressive symptoms in schizophrenic and schizoaffective disorder patients

    Indole pulse signalling regulates the cytoplasmic pH of E. coli in a memory-like manner

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    This is the final version. Available from the publisher via the DOI in this record.The data that support the findings of this study are available in Apollo (University of Cambridge Repository) at https://doi.org/10.17863/CAM.26410.Bacterial cells are critically dependent upon pH regulation. Here we demonstrate that indole plays a critical role in the regulation of the cytoplasmic pH of Escherichia coli. Indole is an aromatic molecule with diverse signalling roles. Two modes of indole signalling have been described: persistent and pulse signalling. The latter is illustrated by the brief but intense elevation of intracellular indole during stationary phase entry. We show that under conditions permitting indole production, cells maintain their cytoplasmic pH at 7.2. In contrast, under conditions where no indole is produced, the cytoplasmic pH is near 7.8. We demonstrate that pH regulation results from pulse, rather than persistent, indole signalling. Furthermore, we illustrate that the relevant property of indole in this context is its ability to conduct protons across the cytoplasmic membrane. Additionally, we show that the efect of the indole pulse that occurs normally during stationary phase entry in rich medium remains as a “memory” to maintain the cytoplasmic pH until entry into the next stationary phase. The indole-mediated reduction in cytoplasmic pH may explain why indole provides E. coli with a degree of protection against stresses, including some bactericidal antibiotics.Leverhulme TrustEngineering and Physical Sciences Research Council (EPSRC)Biotechnology and Biological Sciences Research Council (BBSRC)Winton Programme for the Physics of SustainabilityTrinity-Henry Barlow ScholarshipNational Physical Laboratory (UK)European Research Council (ERC

    The Use of a 3D Printer in Pre-operative Planning for a Patient Requiring Acetabular Reconstructive Surgery.

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    INTRODUCTION: Surgical management of acetabular fractures is often highly complex, and a successful outcome depends upon an appreciation of the fracture pattern and the most appropriate approach to reduce and hold it. Currently, computed tomography (CT) images are used in conjunction with plain x-rays to identify the main fracture components and their spatial relationship to one another, and as such surgeons still have to make decisions based upon their ability to visualise the fracture from the images available. 3D printers have now become widely available and inexpensive, and can be used to rapidly produce life-size models based on CT scans of an individual patient. The availability of patient specific, accurate and detailed models of complex acetabular fractures can aid planning of surgical management on a patient specific basis. CASE REPORT: This report describes the use of a 3D printer to create a life-size model reconstruction of the pelvis of a 48 year old male patient who sustained a left sided associated both column acetabular fracture following a motorbike accident in the Sahara Desert. The model allowed visualisation of the multiple fracture fragments and their relative displacements. The tactile feedback allowed assessment of the different fracture fragments. The relative displacement of the quadrilateral plate and posterior column fragments could be assessed and the surgeon felt that these would be amenable to reduction from an ilioinguinal approach. An anatomic reduction was achieved and was held with the application of a pelvic brim plate with 2 screws lagging the posterior column/quadrilateral plate fragment. CONCLUSION: There are previous examples of 3D models being used in orthopaedic surgery through the use of rapid prototyping, however this method is usually expensive and time consuming. Advances in 3D printer technology offer surgeons a number of advantages when treating these complex fractures. With the ever-increasing economy, ease of use and speed of additive processing, the possible applications of this technology within orthopaedic surgery are numerous. Given the possible applications of this technology, and its ever increasing availability, we feel that its use can only improve patient outcomes and so should be explored further for use in orthopaedic surgery

    The Glucocorticoid Receptor and Certain KRĂśPPEL-Like Transcription Factors have the Potential to Synergistically Stimulate Bovine Herpesvirus 1 Transcription and Reactivation from Latency

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    Bovine herpesvirus 1 (BoHV-1), an important bovine pathogen, establishes life-long latency in sensory neurons within trigeminal ganglia (TG). Stress, as mimicked by the synthetic corticosteroid dexamethasone, consistently induces reactivation in calves latently infected with BoHV-1. Dexamethasone induces expression of several transcription factors in TG neurons during early stages of reactivation, including Krüppel-like transcription factors (KLF): KLF4, KLF6, KLF15, and promyelocytic leukemia zinc finger. Furthermore, the glucocorticoid receptor (GR) is consistently detected in TG neurons expressing viral regulatory proteins during reactivation from latency. The viral immediate early transcription unit 1 (IEtu1) promoter that drives expression of two viral transcription factors (bICP0 and bICP4) contains two GR response elements (GREs) and is stimulated by DEX. KLF15 and the GR form a feed forward transcription loop that synergistically stimulates productive infection and IEtu1 promoter activity. New studies demonstrate the GR and KLF6 synergistically stimulate productive infection and IEtu1 promoter activity if the GREs are intact. Furthermore, the GR and KLF6 interact with wild-type GREs within the IEtu1 promoter, but not GRE mutants. These studies suggest that certain KLF family members and the GR can convert a silent viral genome in latently infected neurons into an actively transcribing genome during reactivation from latency
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