506 research outputs found
Ab initio Study of Misfit Dislocations at the SiC/Si(001) Interface
The high lattice mismatched SiC/Si(001) interface was investigated by means
of combined classical and ab initio molecular dynamics. Among the several
configurations analyzed, a dislocation network pinned at the interface was
found to be the most efficient mechanism for strain relief. A detailed
description of the dislocation core is given, and the related electronic
properties are discussed for the most stable geometry: we found interface
states localized in the gap that may be a source of failure of electronic
devices
Theoretical study of the (3x2) reconstruction of beta-SiC(001)
By means of ab initio molecular dynamics and band structure calculations, as
well as using calculated STM images, we have singled out one structural model
for the (3x2) reconstruction of the Si-terminated (001) surface of cubic SiC,
amongst several proposed in the literature. This is an alternate dimer-row
model, with an excess Si coverage of 1/3, yielding STM images in good accord
with recent measurements [F.Semond et al. Phys. Rev. Lett. 77, 2013 (1996)].Comment: To be published in PRB Rapid. Com
Chiral Polyalkylthiophenes for Organic Light Emitting Diodes
Chiral polyalkylthiophenes are noncentrosymmetric organic materials which can be used
both in second harmonic-generation devices and in polarized light emitting diodes. In this work
we present the synthesis and the characterization of a polyalkylthiophene with a chiral center
very close to the conjugated backbone: poly(3-[(S)-2-methylbutyl]thiophene) (PMBT). Circular
dichroism (CD) measurements have been carried out to ascertain the chirality of these materials.
The CD spectra show intense signals both in mixed solvents and in the solid state. The strong
Cotton effect can be associated to a highly ordered aggregated phase whose nature is still under
investigation. We also present the photo and electroluminescence characterization of single layer
light emitting diode (LED) with the following configuration: ITO (Tin Indium Oxide)/PMBT/Al
Relaxation processes in thiophene-based random copolymers
The relaxation dynamics of soluble polyalkylthiophenes obtained by the random copolymerisation of 3,4-dibutylthiophene and 3-butylthiophene monomers is investigated. In these systems, the effective conjugation length, the optical gap and the non-radiative decay rate are controlled by varying the content of disubstituted monomers, the steric hindrance of which induces a twisting angle between thiophene rings. Several indications are reported in favour of spectral diffusion of the photoexcitations. Migration processes mainly occur within a few tens of picoseconds
GH and IGF System: The Regulatory Role of miRNAs and lncRNAs in Cancer
Growth hormone (GH) and the insulin-like growth factor (IGF) system are involved in many biological processes and have growth-promoting actions regulating cell proliferation, differentiation, apoptosis and angiogenesis. A recent chapter in epigenetics is represented by microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) which regulate gene expression. Dysregulated miRNAs and lncRNAs have been associated with several diseases including cancer. Herein we report the most recent findings concerning miRNAs and lncRNAs regulating GH and the IGF system in the context of pituitary adenomas, osteosarcoma and colorectal cancer, shedding light on new possible therapeutic targets. Pituitary adenomas are increasingly common intracranial tumors and somatotroph adenomas determine supra-physiological GH secretion and cause acromegaly. Osteosarcoma is the most frequent bone tumor in children and adolescents and was reported in adults who were treated with GH in childhood. Colorectal cancer is the third cancer in the world and has a higher prevalence in acromegalic patients
Influence of Ageing Time and Method on Beef Quality and Safety
The effectiveness of dry ageing with regard to retaining meat quality is still subject to debate. At 4 d post mortem, samples of boneless strip loins were excised from young Charolais carcasses and then stored for a further 26 d in a cooler, either vacuum-packaged (VP) or dried-aged (DA). Loin samples were also dissected 7 d post mortem as a control treatment (CT). Chemical, instrumental and microbiological data (n = 18) were determined in longissimus dorsi and underwent ANOVA to estimate the differences in the ageing fixed factor split into two orthogonal contrasts: control vs. aged and VP vs. DA. Ageing loss (both surface dehydration and water purge) was greater in DA compared to VP samples, resulting in the lowest moisture content and highest crude protein and fat percentage in DA loins. The ageing method did not affect meat surface colour, except for redness, which had the lowest value in DA samples. Meat tenderness improved a similar amount following both VP and DA ageing treatments. Compared to the control, prolonged ageing raised both the peroxide value and the total microbial count, especially in DA samples, though both remained within the recommended limits. In summation, both ageing methods improved beef meat tenderisation, preserving its shelf life
Theoretical investigations of a highly mismatched interface: the case of SiC/Si(001)
Using first principles, classical potentials, and elasticity theory, we
investigated the structure of a semiconductor/semiconductor interface with a
high lattice mismatch, SiC/Si(001). Among several tested possible
configurations, a heterostructure with (i) a misfit dislocation network pinned
at the interface and (ii) reconstructed dislocation cores with a carbon
substoichiometry is found to be the most stable one. The importance of the slab
approximation in first-principles calculations is discussed and estimated by
combining classical potential techniques and elasticity theory. For the most
stable configuration, an estimate of the interface energy is given. Finally,
the electronic structure is investigated and discussed in relation with the
dislocation array structure. Interface states, localized in the heterostructure
gap and located on dislocation cores, are identified
A protocol for Italian validation of DEMQoL-Proxy Scale: assessing the Quality of Life of people with moderate or mild dementia
In this paper, we propose an adaptation of a protocol for a tool's validation. We have utilized this phases-theory to validate in Italian language an instrument to assess Quality of Life for people with moderate or mild dementia. We will explain the example of our Italian validation of DEMQoL-Proxy considering each De Vellis's phase. We will explain our application of De Vellis's model to Italian example described. For the first three phases, we reproduced the original validating study in which authors (Smith et al., 2005) defined what to measure, how generate a set of items and the structure of the scale. Indeed, for the last five phases we explained the adaptation of De Vellis's model to Italian validation. We hope that this model could be effective to validating goals, for researchers and in particular for all professionals who deal with caregivers and patients with moderate and mild dementia. Furthermore, the measurement of the Quality of Life makes the scale widely useful within the various professional specialties and setting. Finally, thanks to the methodological assumptions adopted following the De Vellis's eight-phase model, we can affirm that this first Italian pre-validation of the DEMQoL-Proxy seems to be an excellent forerunner for its effective validation in the Italian context
THEORETICAL STUDY OF Si and N ADSORPTION ON THE Si-TERMINATED SiC(001) SURFACE
We report the results of first principles molecular dynamics simulations of the adsorption of Si and N atoms on a Si-terminated p(2 x 1) SiC(001) surface. In particular, we discuss different structural models for the Si-rich (3 x 2) surface, and the adsorption of 1/8, 1/2 and 1 monolayer nitrogen on the p(2 x 1) surface. Our simulations show that a SiC(001)-p(2 x 1) surface covered by a nitrogen monolayer is an inert substrate which inhibits growth
Safety and feasibility of thullium laser transurethral resection of prostate for the treatment of benign prostatic enlargement in overweight patients
Objective: We aimed to determine safety and feasibility of thulium laser transurethral vapoenucleation of prostate (ThuVEP) for treatment of obese patients affected by benign prostatic hyperplasia (BPH). Methods: We retrospectively analysed data of 452 patients with BPH who underwent ThuVEP from February 2012 to March 2016 in a single center. Patients were divided into three groups according to body mass index (BMI, kg/m2): Normal weight (18.5 64 BMI < 25; Group A), overweight (25 64 BMI < 30; Group B) and obese (BMI 65 30; Group C), for a total of 412 patients evaluable for this study. Preoperative total serum prostate-specific antigen (PSA), digital rectal examination of the prostate, transrectal ultrasound (TRUS), renal ultrasound, urine culture, uroflowmetry, International Prostate Symptoms Score (IPSS), and Quality of Life (QoL) score were analyzed. Post-operative complications, hospital stay and days of catheterization, questionnaires and uroflowmetry at 1 and 3 months after surgery were evaluated. Preoperative data, surgical outcomes, complication rate and clinical outcomes were compared between groups. Results: The median age of patients was 69 years (Interquartile Range [IQR 10]). The preoperative median IPSS among groups was 19 (IQR 8.75), 20 (IQR 10), and 18 (IQR 10) respectively. At 1 and 3 months of follow-up, this value was 8 (IQR 7), 8 (IQR 4), 7 (IQR 5) and 5 (IQR 6.25), 5 (IQR 6), 6 (IQR 5), respectively (all p between groups > 0.05). There was no statistically significant difference among three groups as for hospital stay and days of catheterization (p > 0.05). Conclusion: Our results showed that ThuVEP was safe and feasible even in overweight patients with substantially enlarged prostate
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