715 research outputs found
Spin-enhanced magnetocaloric effect in molecular nanomagnets
An unusually large magnetocaloric effect for the temperature region below 10 K is found for the Fe-14 molecular nanomagnet. This is to large extent caused by its extremely large spin S ground state combined with an excess of entropy arising from the presence of low-lying excited S states. We also show that the highly symmetric Fe-14 cluster core, resulting in small cluster magnetic anisotropy, enables the occurrence of long-range antiferromagnetic order below T-N=1.87 K
DIGITAL TECHNOLOGIES IN COMPLETE REMOVABLE DENTURE: A CASE SERIES
Aim: complete removable denture has been the last prosthetic
procedure to follow the digitization because of drawbacks into
the intraoral scans of edentulous arches; in addition, it is impossible
to record muco-compressive impressions through
IOS. So, a full digital procedure is not yet conceivable.
We considered the possibility of an “hybrid” protocol thanks to
a specific software. The hybrid protocol requires traditional
techniques for the anatomical impression followed by laboratory
scan of casts and wax.
Methods: the software consists in two synergic programs:
- Ruthinium Digital Preview allows to have a picture of the prosthetic
project and change it previously, thanks to two calibrated
photographs.
- Ruthinium Denture Guide is a 3D software that helps laboratory
work into denture production, particularly to a correct setting of
acrylic teeth. The planned dental setting is printed in a template.
Template and base plate, both 3D printed, are connected thanks
to a structure that ensures the designed occlusal scheme.
Results: the collected clinical cases did not allow a statistic
analysis about patient and clinical satisfaction through evaluation
questionnaires.
Conclusion: it looks like that patients appreciate the prosthetic
rehabilitation previsualization and in particular being actively
involved in aesthetic choices. Clinically, it appears to be a
shorter need for touch-ups at the last appointment; probably
because of the 3D tooth position planning
Low field magnetotransport in strained Si/SiGe cavities
Low field magnetotransport revealing signatures of ballistic transport
effects in strained Si/SiGe cavities is investigated. We fabricated strained
Si/SiGe cavities by confining a high mobility Si/SiGe 2DEG in a bended nanowire
geometry defined by electron-beam lithography and reactive ion etching. The
main features observed in the low temperature magnetoresistance curves are the
presence of a zero-field magnetoresistance peak and of an oscillatory structure
at low fields. By adopting a simple geometrical model we explain the
oscillatory structure in terms of electron magnetic focusing. A detailed
examination of the zero-field peak lineshape clearly shows deviations from the
predictions of ballistic weak localization theory.Comment: Submitted to Physical Review B, 25 pages, 7 figure
Essential singularity in the Renyi entanglement entropy of the one-dimensional XYZ spin-1/2 chain
We study the Renyi entropy of the one-dimensional XYZ spin-1/2 chain in the
entirety of its phase diagram. The model has several quantum critical lines
corresponding to rotated XXZ chains in their paramagnetic phase, and four
tri-critical points where these phases join. Two of these points are described
by a conformal field theory and close to them the entropy scales as the
logarithm of its mass gap. The other two points are not conformal and the
entropy has a peculiar singular behavior in their neighbors, characteristic of
an essential singularity. At these non-conformal points the model undergoes a
discontinuous transition, with a level crossing in the ground state and a
quadratic excitation spectrum. We propose the entropy as an efficient tool to
determine the discontinuous or continuous nature of a phase transition also in
more complicated models.Comment: 5 pages, 2 figure
Hypoproteic diet in patients' community: reports from University of Pisa
Nutrition is considered by the National Health Authorities as part of the clinical care process. In this perspective, the catering service of a hospital represents a powerful therapeutic and educational aid for the in-patients.The catering service of our University Hospital in Pisa is based on a collection of standardized diets with indications concerning the type of patient which they are addressed. The present paper deals with our experience in this field, and in particular with the diets for renal patients.The so called "special" diets, such as low protein (0.6 g / kg b. w. / day) low phosphorus diet, the low protein (0.7 g / kg b.w./ day) vegetarian diet and the very low protein (0.3 g / kg b. w./day) low phosphorus diet are prescribed by the doctors and developed by the dietician for the individual patient.Since its preparation, the low-protein diets have several critical points, namely processing - packaging and distribution of the diet, no customization, the low protein artificial foods).In order t..
Conductance quantization in etched Si/SiGe quantum point contacts
We fabricated strongly confined Schottky-gated quantum point contacts by
etching Si/SiGe heterostructures and observed intriguing conductance
quantization in units of approximately 1e2/h. Non-linear conductance
measurements were performed depleting the quantum point contacts at fixed
mode-energy separation. We report evidences of the formation of a half 1e2/h
plateau, supporting the speculation that adiabatic transmission occurs through
1D modes with complete removal of valley and spin degeneracies.Comment: to appear in Physical Review
Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings
Under the terms of the CC BY license.-- et al.A detailed experimental investigation of the effects giving rise to the magnetic energy level structure in the vicinity of the level crossing (LC) at low temperature is reported for the open antiferromagnetic molecular ring CrZn. The study is conducted by means of thermodynamic techniques (torque magnetometry, magnetization and specific heat measurements) and microscopic techniques (nuclear magnetic resonance line width, nuclear spin lattice, and spin-spin relaxation measurements). The experimental results are shown to be in excellent agreement with theoretical calculations based on a minimal spin model Hamiltonian, which includes a Dzyaloshinskii-Moriya interaction. The first ground state level crossing at μH = 2.15 T is found to be an almost true LC while the second LC at μH = 6.95 T has an anti-crossing gap of Δ = 0.19 K. In addition, both NMR and specific heat measurements show the presence of a level anti-crossing between excited states at μH = 4.5 T as predicted by the theory. In all cases, the fit of the experimental data is improved by introducing a distribution of the isotropic exchange couplings (J), i.e., using a J strain model. The peaks at the first and second LCs in the nuclear spin-lattice relaxation rate are dominated by inelastic scattering and a value of Γ ∼ 10 rad/s is inferred for the life time broadening of the excited state of the open ring, due to spin phonon interaction. A loss of NMR signal (wipe-out effect) is observed for the first time at LC and is explained by the enhancement of the spin-spin relaxation rate due to the inelastic scattering.This work was financially supported by the Italian FIRB Project No. RBFR12RPD1 of the Italian MIUR “New Challenges in Molecular Nanomagnetism: From Spin Dynamics to Quantum-Information Processing.”Peer Reviewe
Layered gadolinium hydroxides for low-temperature magnetic cooling
Layered gadolinium hydroxides have revealed to be excellent candidates for cryogenic magnetic refrigeration. These materials behave as pure 2D magnetic systems with a Heisenberg-Ising critical crossover, induced by dipolar interactions. This 2D character and the possibility offered by these materials to be delaminated open the possibility of rapid heat dissipation upon substrate deposition
Therapeutic targeting of CK2 in acute and chronic leukemias
CK2 is a ubiquitously expressed, constitutively active Ser/Thr protein kinase, which is considered the most pleiotropic protein kinase in the human kinome. Such a pleiotropy explains the involvement of CK2 in many cellular events. However, its predominant roles are stimulation of cell growth and prevention of apoptosis. High levels of CK2 messenger RNA and protein are associated with CK2 pathological functions in human cancers. Over the last decade, basic and translational studies have provided evidence of CK2 as a pivotal molecule driving the growth of different blood malignancies. CK2 overexpression has been demonstrated in nearly all the types of hematological cancers, including acute and chronic leukemias, where CK2 is a key regulator of signaling networks critical for cell proliferation, survival and drug resistance. The findings that emerged from these studies suggest that CK2 could be a valuable therapeutic target in leukemias and supported the initiation of clinical trials using CK2 antagonists. In this review, we summarize the recent advances on the understanding of the signaling pathways involved in CK2 inhibition-mediated effects with a particular emphasis on the combinatorial use of CK2 inhibitors as novel therapeutic strategies for treating both acute and chronic leukemia patients
A collimation system for ELI-NP Gamma Beam System - design and simulation of performance
The purpose of this study was to evaluate the performance and refine the design of the collimation system for the gamma radiation source (GBS) currently being realised at ELI-NP facility. The gamma beam, produced by inverse Compton scattering, will provide a tunable average energy in the range between 0.2 and 20 MeV, an energy bandwidth 0.5% and a flux of about 108 photons/s. As a result of the inverse Compton interaction, the energy of the emitted radiation is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [1,2]. Therefore, the required energy bandwidth can be obtained only by developing a specific collimation system of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation for ELI-NP-GBS must be continuously adjustable in a range from about 700 to 60 μrad, to obtain the required parameters in the entire energy range. The solution identified is a stack of adjustable slits, arranged with a relative rotation around the beam axis to obtain an hole with an approximately circular shape. In this contribution, the final collimation design and its performance evaluated by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline are presented
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