342 research outputs found
Electron localization and possible phase separation in the absence of a charge density wave in single-phase 1T-VS
We report on a systematic study of the structural, magnetic and transport
properties of high-purity 1T-VS powder samples prepared under high
pressure. The results differ notably from those previously obtained by
de-intercalating Li from LiVS. First, no Charge Density Wave (CDW) is found
by transmission electron microscopy down to 94 K. Though, \textit{ab initio}
phonon calculations unveil a latent CDW instability driven by an acoustic
phonon softening at the wave vector (0.21,0.21,0)
previously reported in de-intercalated samples. A further indication of latent
lattice instability is given by an anomalous expansion of the V-S bond distance
at low temperature. Second, infrared optical absorption and electrical
resistivity measurements give evidence of non metallic properties, consistent
with the observation of no CDW phase. On the other hand, magnetic
susceptibility and NMR data suggest the coexistence of localized moments with
metallic carriers, in agreement with \textit{ab initio} band structure
calculations. This discrepancy is reconciled by a picture of electron
localization induced by disorder or electronic correlations leading to a phase
separation of metallic and non-metallic domains in the nm scale. We conclude
that 1T-VS is at the verge of a CDW transition and suggest that residual
electronic doping in Li de-intercalated samples stabilizes a uniform CDW phase
with metallic properties.Comment: 22 pages, 10 Figures. Full resolution pictures available at
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.23512
Commensurate structural modulation in the charge- and orbitally-ordered phase of the quadruple perovskite (NaMn)MnO
By means of synchrotron x-ray and electron diffraction, we studied the
structural changes at the charge order transition =176 K in the
mixed-valence quadruple perovskite (NaMn)MnO. Below we
find satellite peaks indicating a commensurate structural modulation with the
same propagation vector q =(1/2,0,-1/2) of the CE magnetic order that appears
at low temperature, similarly to the case of simple perovskites like
LaCaMnO. In the present case, the modulated structure
together with the observation of a large entropy change at gives
evidence of a rare case of full Mn/Mn charge and orbital order
consistent with the Goodenough-Kanamori model.Comment: Accepted for publication in Phys. Rev. B Rapid Communication
CT imaging findings of abdominopelvic vascular compression syndromes: what the radiologist needs to know
Abdominopelvic vascular compression syndromes include a variety of uncommon conditions characterized by either extrinsic compression of blood vessels by adjacent anatomical structures (i.e., median arcuate ligament syndrome, nutcracker syndrome, May-Thurner syndrome) or compression of hollow viscera by adjacent vessels (i.e., superior mesenteric artery syndrome, ureteropelvic junction obstruction, ureteral vascular compression syndromes, portal biliopathy). These syndromes can be unexpectedly diagnosed even in asymptomatic patients and the predisposing anatomic conditions can be incidentally discovered on imaging examinations performed for other indications, or they can manifest with atypical abdominal symptoms and acute complications, which may lead to significant morbidity if unrecognized. Although computed tomography (CT) is an accurate noninvasive technique for their detection, the diagnosis remains challenging due to the uncommon clinical presentation and often overlooked imaging features. Dynamic imaging may be performed in order to evaluate patients with inconstant symptoms manifesting in a specific position. The purposes of this paper are to review the CT imaging findings of abdominopelvic vascular compression syndromes, correlating with anatomical variants and to provide key features for the noninvasive imaging diagnosis
CT angiography for the assessment of EVAR complications: a pictorial review
Endovascular aneurysm repair (EVAR) is a minimally invasive treatment proposed as an alternative to open repair in patients with abdominal aortic aneurysms. EVAR consists in a stent-graft placement within the aorta in order to exclude the aneurysm from arterial circulation and reduce the risk of rupture. Knowledge of the various types of devices is mandatory because some stents/grafts are more frequently associated with complications. CT angiography is the gold standard diagnostic technique for preprocedural planning and postprocedural surveillance. EVAR needs long-term follow-up due to the high rate of complications. Complications can be divided in endograft device-related and systemic complications. The purpose of this article is to review the CT imaging findings of EVAR complications and the key features for the diagnosis
Organoindate room temperature ionic liquid: Synthesis, physicochemical properties and application
The combination of equimolar amounts of solid 1-n-butyl-3-methylimidazolum chloride (BMI-Cl) with solid indium trichloride affords the new room temperature and air stable ionic liquid BMI.InCl4 (mp -6 degreesC). The major physicochemical properties (density, viscosity, electrical conductivity and electrochemical window) of BMI.InCl4 are complementary to those of classical tetrafluoroborate or hexafluorophosphate analogues. However, this liquid possesses similar Lewis acidity properties to those of organoaluminate melts and can be used as recyclable media, as demonstrated here for the tetrahydropyranylation of alcohols.81155115
Colloidal Synthesis and Characterization of Tetrapod-Shaped Magnetic Nanocrystals
Tetrapod-shaped maghemite nanocrystals are synthesized by manipulating the decomposition of iron pentacarbonyl in a ternary surfactant mixture under mild thermal conditions. Adjustment of the reaction parameters allows for the systematic tuning of both the width and the length of the tetrapod arms, which grow preferentially along the 〈111〉 easy axis direction. Such degree of control leads to modulation of the magnetic behavior of the nanocrystals, which evolves systematically as their surface magnetization phase and shape anisotropy are progressively increased
4th ESPT Conference:pharmacogenomics and personalized medicine - research progress and clinical implementation
The Fourth European Society of Pharmacogenomics and Personalized Therapy biennial conference was organized in collaboration with the Italian Society of Personalized Medicine (SIMeP) and was held at Benedictine Monastery of San Nicolò l'Arena in Catania, Sicily (Italy) on 4-7 October 2017. The congress addressed the research progress and clinical implementation in pharmacogenomics and personalized medicine. The Fourth European Society of Pharmacogenomics and Personalized Therapy congress brought together leading international scientists and healthcare professionals actively working in the fields of pharmacogenomics and personalized therapy. Altogether, 25 speakers in 15 session comprehensively covered broad spectrum of pharmacogenetics and pharmacogenomics research, clinical applications in different clinical disciplines attended by 270 delegates
Emergency hernia repair in the elderly. multivariate analysis of morbidity and mortality from an Italian registry
Purpose The incidence of inguinal hernia is higher in elderly because of aging-related diseases like prostatism, bronchitis, collagen laxity. A conservative management is common in elderly to reduce surgery-related risks, however watchful waiting can expose to obstruction and strangulation. The aim of the present study was to assess the impact of emergency surgery in a large series of elderly with complicated groin hernia and to identify the independent risk factors for postoperative morbidity and mortality. The predictive performance of prognostic risk scores has been also assessed. Methods This is a prospective observational study carried out between January 2017 and June 2018 in elderly patients who underwent emergency surgery for complicated hernia in 38 Italian hospitals. Pre-operative, surgical and postoperative data were recorded for each patient. ASA score, Charlson's comorbidity index, P-POSSUM and CR-POSSUM were assessed. Results 259 patients were recruited, mean age was 80 years. A direct repair without mesh was performed in 62 (23.9%) patients. Explorative laparotomy was performed in 56 (21.6%) patients and bowel resection was necessary in 44 (17%). Mortality occurred in seven (2.8%) patients. Fifty-five (21.2%) patients developed complications, 12 of whom had a major one. At univariate and multivariate analyses, Charlson's comorbidity index >= 6, altered mental status, and need for laparotomy were associated with major complications and mortality Conclusion Emergency surgery for complicated hernia is burdened by high morbidity and mortality in elderly patients. Preoperative comorbidity played a pivotal role in predicting complications and mortality and therefore Charlson's comorbidity index could be adopted to select patients for elective operation
Metabolic Syndrome (MetS), Systemic Inflammatory Response Syndrome (SIRS), and Frailty: Is There any Room for Good Outcome in the Elderly Undergoing Emergency Surgery?
Background: Patients with MetS or SIRS experience higher rates of mortality and morbidity, across both cardiac and noncardiac surgery. Frailty assessment has acquired increasing importance in recent years as it predisposes elderly patients to a worse outcome. The aim of our study was to investigate the influence of MetS, SIRS, and with or without frailty on elderly patients undergoing emergency surgical procedures. Methods: We analyzed data of all patients with nonmalignant diseases requiring an emergency surgical procedure from January 2017 to December 2020. The occurrence of MetS was identified using modified definition criteria used by the NCEP-ATP III Expert Panel: obesity, hypertension, diabetes, or if medication for high triglycerides or for low HDL cholesterol was taken. Systemic inflammatory response syndrome (SIRS) was evaluated according to the original consensus study (Sepsis-1). The frailty profile was investigated by the 5-modified Frailty Index (5-mFI) and the Emergency Surgery Frailty Index (EmSFI). Postoperative complications have been reported and categorized according to the Clavien–Dindo (C–D) classification system. Morbidity and mortality have been mainly considered as the 30-day standard period definition. Results: Of the 2,318 patients included in this study, 1,010 (43.6%) fulfilled the criteria for MetS (MetsG group). Both 5-Items score and EmsFI showed greater fragility in patients with MetS. All patients with MetS showed more frequently a CACI index greater than 6. The occurrence of SIRS was higher in MetSG. LOS was longer in patients with MetS (MetSG 11.4 ± 12 days vs. n-MetSG 10.5 ± 10.2 days, p = 0.046). MetSG has a significantly higher rate of morbidity (353 (35.%) vs. 385 (29.4%), p = 0.005). The mortality rate in patients with MetS (98/1010, 10%) was similar to that in patients without it (129/1308, 10%). Considering patients with MetS who developed SIRS and those who had frailty or both, the occurrence of these conditions was associated with a higher rate of morbidity and mortality. Conclusion: Impact of MetS and SIRS on elderly surgical patient outcomes has yet to be fully elucidated. The present study showed a 43.6% incidence of MetS in the elderly population. In conclusion, age per se should be not considered anymore as the main variable to estimate patient outcomes, while MetS and Frailty should have always a pivotal role
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