We investigated the atomic structure of different kinds of grain boundaries on highly oriented pyrolytic graphite (HOPG) by scanning tunneling microscopy. We categorized several grain boundary ...configurations as a function of the misorientation angle between the adjacent grains, highlighting the occurrence of double grain boundaries (i.e., systems of two grain boundaries separated by a nanometric-scale inner region with specific atomic arrangement) for misorientation angles in the range 22°–32°. By using Molecular Dynamics simulations, we analyzed the structure and energy stability of single and double grain boundaries according to the misorientation angle. The experimental evidence is corroborated by Molecular Dynamics results and total energy calculations, which found a comparable stability between single and double grain boundaries for the same misorientation angle range. Our combination of experimental measurements and theoretical calculation extends the understanding of the structural configuration of large angle grain boundaries beyond the range of misorientation angles reported to date.
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In vivo dosimetry (IVD) is the last step of a radiotherapy quality control program aimed to ensure that the dose delivered is in agreement with that prescribed. IVD procedures based on single ...detectors are time-consuming and impossible to use for the modern radiotherapy techniques, based on static or kinetic beams (modulated in intensity fluence); this means that more efficient and practical methods are highly recommended. The practical method SOFTDISO, based on the use of electronic portal image device (EPID), provides two tests (i) the R ratio between the reconstructed and the planned isocenter doses to verify an agreement within 5% and (ii) the γ-analysis of the EPID images, to verify γ% ≥ 90% and γ
mean
≤ 0.4. This paper reports the results of 11,357 IVD tests carried out for 823 patients treated by three-dimensional conformal radiation therapy and volumetric modulated arc therapy techniques. In particular, the dose disagreements are reported distinguishing two kinds of causes, those of (i) class 1 that includes the errors due to inadequate quality controls and (ii) the class 2, due to patient morphological changes. About the tests out of tolerance, 6% were by VMAT and 21% by 3DCRT, but taking into account the only class 1 of errors, i.e., removing the causes of class 2, only 7% of patients examined presented at least one of the three mean indexes out of tolerance. The workload for IVD on 9 patients/day per linac is about 52 min/day but recently, a new automated SOFTDISO version has been implemented to reduce the time to about 34 min/day.
In this paper we clarify the transformation mechanism of 3C-SiC into graphene upon thermal decomposition, by a combination of high resolution Scanning Tunneling Microscopy (STM) images and first ...principle calculations. We studied the transition from 3C-SiC to graphene by high temperature annealing of C-terminated 3C SiC(111)/Si(111) samples in Ultra High Vacuum. By using STM we were able to observe very clear atomic resolution images of the transition from SiC (√3×√3)R30° to a new intermediate stage SiC 32×√3R30° (very close to the graphene (2×2) reconstruction) after annealing at 1250°C. We also obtained images of the transformation of the intermediate structure into a (1×1) monolayer graphene, caused by further sublimation of atoms in the subsurface layer. We have interpreted the results by using Density Functional Theory – Local Density Approximation calculations, which give full account of the SiC (√3×√3)R30° reconstruction, but fail to describe the SiC 32×√3R30° structure due to its incommensurability with the 3C-SiC(111) lattice.
Background
Most methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted ...that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo‐colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing.
Methods
Twelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes.
Key Results
Small bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103).
Conclusions & Inferences
Ingestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well‐tolerated, could be a useful way of assessing colonic motility in future studies.
Oral polyethylene glycol (PEG) electrolyte was used as standardized colonic stimulation and magnetic resonance imaging (MRI) was used to monitor fluid distributions and gastrointestinal motility non‐invasively. PEG electrolyte solution increased the small bowel water content fourfold. The size of the colon doubled after dosing and the ascending colon motility index raised markedly, the increase was dose dependent. Such a challenge, being well‐tolerated, could be a useful way of assessing colonic motility in future studies.
Several multilayer InAs/GaAs(001) samples were grown in a Molecular Beam Epitaxy chamber under critical growth conditions in order to induce the self-assembling of chains of InAs Quantum Dots over ...mounded GaAs surfaces. As the number of deposited layers was increased, an increasing in-line ordering was observed. Finite Element Method simulations confirmed this trend which is driven mainly by the propagation of the elastic strain field through the layers. On the other hand, the morphological features of the surface contribute to improving the alignment of the InAs Quantum Dots in every chain.
•In Quantum Dot multilayers, we have measured an increasing correlation of the Quantum Dot in-line distances.•The increase of the in-line Quantum Dot ordering is driven mainly by the propagation of the elastic strain field through the layers.•Finite Element Method simulations confirm a tendency towards in-line ordering as function of the increasing number of layers.•The elongated step bunchings are responsible for an improvement of the alignment properties of Quantum Dot chains.
The aim of this study was to report a monoinstitutional multidisciplinary experience about the use of multiparametric imaging to identify the areas with higher risk of relapse in localized prostate ...cancer, with the purpose of allowing a biologically planned target dose escalation.
We performed a retrospective evaluation of patients diagnosed with prostate cancer who received treatments at our Interventional Oncology Center with interstitial interventional radiotherapy from 2014 to 2022. Inclusion criteria were histologically confirmed localized prostate cancer; and National Comprehensive Cancer Network (NCCN) risk class unfavorable intermediate or high/very high risk. The diagnostic work-up included multiparametric Magnetic resonance imaging (MRI), multiparametric Transrectal ultrasound (TRUS), Positron Emission Tomography Computed Tomography (PET-CT) with choline or PSMA (or alternatively bone scan). All patients were assessed and received one treatment with interstitial high-dose-rate interventional radiotherapy (brachytherapy) delivering external beam radiotherapy (46 Gy). All procedures were performed using transrectal ultrasound guidance under general anesthesia and the prescribed doses were 10 Gy to the whole prostate, 12 Gy to the peripheral zone and 15 Gy to the areas at risk.
We report the data of 21 patients who were considered for the statistical analysis with a mean age of 62.5 years. The mean PSA nadir was 0.03 ng/ml (range 0-0.09). So far, no biochemical nor radiological recurrences have been recorded in our series. Regarding acute toxicity, the most commonly reported side effects were G1 urinary in 28.5% of patients and G2 urinary in 9.5%; all recorded acute toxicities resolved spontaneously.
We present a real-life experience of biologically planned local dose escalation by interventional radiotherapy (brachytherapy) boost, followed by external beam radiotherapy in patients with intermediate unfavorable- or high/very high risk. The local control and the biochemical control rates are proved to be excellent and the toxicity profile tolerable.
Far-UV Circular Dichroism experiments and Atomic Force Microscopy tomography are employed to assess the impact of β-sheet breakers on the Aβ1–40 peptide aggregation process in the presence of Cu2+ or ...Zn2+ transition metals. In this work we focus on two specific 5-amino acids long β-sheet breakers, namely the LPFFD Soto peptide, already known in the literature, and the LPFFN peptide recently designed and studied by our team. We provide evidence that both β-sheet breakers are effective in reducing the Aβ1–40 aggregation propensity, even in the presence of metal ions.
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•The effect of Cu(II)/Zn(II) ions and β-sheet breakers on Aβ1–40 fibril formation•CD spectroscopy and AFM monitor secondary structure changes and fibril formation•No β-sheet structure transition and no fibrils in the presence of β-sheet breakers•β-Sheet breakers peptides prevent fibril formation in the presence of metal ions.
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