Grafting Single Molecule Magnets on Gold Nanoparticles

The chemical synthesis and characterization of the first hybrid material composed by gold nanoparticles and single molecule magnets (SMMs) are described. Gold nanoparticles are functionalized via ligand exchange using a tetrairon(III) SMM containing two 1,2‐dithiolane end groups. The grafting is evidenced by the shift of the plasmon resonance peak recorded with a UV–vis spectrometer, by the suppression of nuclear magnetic resonance signals, by X‐ray photoemission spectroscopy peaks, and by transmission electron microscopy images. The latter evidence the formation of aggregates of nanoparticles as a consequence of the cross‐linking ability of Fe₄ through the two 1,2‐dithiolane rings located on opposite sides of the metal core. The presence of intact Fe₄ molecules is directly proven by synchrotron‐based X‐ray absorption spectroscopy and X‐ray magnetic circular dichroism spectroscopy, while a detailed magnetic characterization, obtained using electron paramagnetic resonance and alternating‐current susceptibility, confirms the persistence of SMM behavior in this new hybrid nanostructure.     

Enhancement of the electrical characteristics of MOS capacitors by reducing the organic content of H2O-diluted Spin-On-Glass based oxides

In this work, the physical, chemical and electrical properties of Metal-Oxide-Semiconductor (MOS) capacitors with Spin-On-Glass (SOG)-based thin films as gate dielectric have been investigated. Experiments of SOG diluted with two different solvents (2-propanol and deionized water) were done in order to reduce the viscosity of the SOG solution so that thinner films (down to ∼20 nm) could be obtained and their general characteristics compared. Thin films of SOG were deposited on silicon by the sol-gel technique and they were thermally annealed using conventional oxidation furnace and Rapid Thermal Processing (RTP) systems within N₂ ambient after deposition. SOG dilution using non-organic solvents like deionized water and further annealing (at relatively high temperatures ≥450 °C) are important processes intended to reduce the organic content of the films. Fourier-Transform Infrared (FTIR) Spectroscopy results have shown that water-diluted SOG films have a significant reduction in their organic content after increasing annealing temperature and/or dilution percentage when compared to those of undiluted SOG films. Both current-voltage (I-V) and capacitance-voltage (C-V) measurements show better electrical characteristics for SOG-films diluted in deionized water compared to those diluted in 2-propanol (which is an organic solvent). The electrical characteristics of H₂O-diluted SOG thin films are very similar to those obtained from high quality thermal oxides so that their application as gate dielectrics in MOS devices is promising. Finally, it has been demonstrated that by reducing the organic content of SOG-based thin films, it is possible to obtain MOS devices with better electrical properties.     

Towards ultrastrong glasses

The development of new glassy materials is key for addressing major global challenges in energy, medicine, and advanced communications systems. For example, thin, flexible, and large-area glass substrates will play an enabling role in the development of flexible displays, roll-to-roll processing of solar cells, next-generation touch-screen devices, and encapsulation of organic semiconductors. The main drawback of glass and its limitation for these applications is its brittle fracture behavior, especially in the presence of surface flaws, which can significantly reduce the practical strength of a glass product. Hence, the design of new ultrastrong glassy materials and strengthening techniques is of crucial importance. The main issues regarding glass strength are discussed, with an emphasis on the underlying microscopic mechanisms that are responsible for mechanical properties. The relationship among elastic properties and fracture behavior is also addressed, focusing on both oxide and metallic glasses. From a theoretical perspective, atomistic modeling of mechanical properties of glassy materials is considered. The topological origin of these properties is also discussed, including its relation to structural and chemical heterogeneities. Finally, comments are given on several toughening strategies for increasing the damage resistance of glass products.     

Hierarchically Structured Magnetic Nanoconstructs with Enhanced Relaxivity and Cooperative Tumor Accumulation

Iron oxide nanoparticles are formidable multifunctional systems capable of contrast enhancement in magnetic resonance imaging, guidance under remote fields, heat generation, and biodegradation. Yet, this potential is underutilized in that each function manifests at different nanoparticle sizes. Here, sub‐micrometer discoidal magnetic nanoconstructs are realized by confining 5 nm ultra‐small super‐paramagnetic iron oxide nanoparticles (USPIOs) within two different mesoporous structures, made out of silicon and polymers. These nanoconstructs exhibit transversal relaxivities up to ≈10 times (r ₂ ≈ 835 mm ^?1 s^?1) higher than conventional USPIOs and, under external magnetic fields, collectively cooperate to amplify tumor accumulation. The boost in r ₂ relaxivity arises from the formation of mesoscopic USPIO clusters within the porous matrix, inducing a local reduction in water molecule mobility as demonstrated via molecular dynamics simulations. The cooperative accumulation under static magnetic field derives from the large amount of iron that can be loaded per nanoconstuct (up to ≈65 fg) and the consequential generation of significant inter‐particle magnetic dipole interactions. In tumor bearing mice, the silicon‐based nanoconstructs provide MRI contrast enhancement at much smaller doses of iron (≈0.5 mg of Fe kg^?1 animal) as compared to current practice.     

用于地毯和纺织品的新纤维

在意大利Aquafil公司与特伦托大学合作进行的科研工作的基础上,介绍和讨论了用于地毯和纺织品的新纤维的新的试验方法.此外,指出了各种创新的多种聚合物复合所得的结果.结果证实,由反应纺丝得到的多种聚合物的复合纤维,力学性质具有单值性.     

Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation

Celiac disease (CD) is a complex multi-organ disease with a high prevalence of extra-intestinal involvement, including neurological and psychiatric manifestations, such as cerebellar ataxia, peripheral neuropathy, epilepsy, headache, cognitive impairment, and depression. However, the mechanisms behind the neurological involvement in CD remain controversial. Recent evidence shows these can be related to gluten-mediated pathogenesis, including antibody cross-reaction, deposition of immune-complex, direct neurotoxicity, and in severe cases, vitamins or nutrients deficiency. Here, we have summarized new evidence related to gut microbiota and the so-called “gut-liver-brain axis” involved in CD-related neurological manifestations. Additionally, there has yet to be an agreement on whether serological or neurophysiological findings can effectively early diagnose and properly monitor CD-associated neurological involvement; notably, most of them can revert to normal with a rigorous gluten-free diet. Moving from a molecular level to a symptom-based approach, clinical, serological, and neurophysiology data might help to disentangle the many-faceted interactions between the gut and brain in CD. Eventually, the identification of multimodal biomarkers might help diagnose, monitor, and improve the quality of life of patients with “neuroCD”.     

Primary Aldosteronism and Resistant Hypertension: A Pathophysiological Insight

Primary aldosteronism (PA) is a pathological condition characterized by an excessive aldosterone secretion; once thought to be rare, PA is now recognized as the most common cause of secondary hypertension. Its prevalence increases with the severity of hypertension, reaching up to 29.1% in patients with resistant hypertension (RH). Both PA and RH are “high-risk phenotypes”, associated with increased cardiovascular morbidity and mortality compared to non-PA and non-RH patients. Aldosterone excess, as occurs in PA, can contribute to the development of a RH phenotype through several mechanisms. First, inappropriate aldosterone levels with respect to the hydro-electrolytic status of the individual can cause salt retention and volume expansion by inducing sodium and water reabsorption in the kidney. Moreover, a growing body of evidence has highlighted the detrimental consequences of “non-classical” effects of aldosterone in several target tissues. Aldosterone-induced vascular remodeling, sympathetic overactivity, insulin resistance, and adipose tissue dysfunction can further contribute to the worsening of arterial hypertension and to the development of drug-resistance. In addition, the pro-oxidative, pro-fibrotic, and pro-inflammatory effects of aldosterone may aggravate end-organ damage, thereby perpetuating a vicious cycle that eventually leads to a more severe hypertensive phenotype. Finally, neither the pathophysiological mechanisms mediating aldosterone-driven blood pressure rise, nor those mediating aldosterone-driven end-organ damage, are specifically blocked by standard first-line anti-hypertensive drugs, which might further account for the drug-resistant phenotype that frequently characterizes PA patients.     

Ionophore-mediated uptake of ciprofloxacin and vincristine into large unilamellar vesicles exhibiting transmembrane ion gradients

A new method, based on the ion-translocating properties of the ionophores nigericin and A23187, is described for loading large unilamellar vesicles (LUVs) with the drugs vincristine and ciprofloxacin. LUVs composed of distearoylphosphatidylcholine/cholesterol (DSPC/Chol) (55:45 mol/mol) or sphingomyelin (SPM)/Chol (55:45 mol/mol) exhibiting a transmembrane salt gradient (for example, internal solution 300 mM MnSO4 or K2SO4; external solution 300 mM sucrose) are incubated in the presence of drug and, for experiments involving divalent cations, the chelator EDTA. The addition of ionophore couples the outward movement of the entrapped cation to the inward movement of protons, thus acidifying the vesicle interior. External drugs that are weak bases can be taken up in response to this induced transmembrane pH gradient. It is shown that both nigericin and A23187 facilitate the rapid uptake of vincristine and ciprofloxacin, with entrapment levels approaching 100% and excellent retention in vitro. Following drug loading, the ionophores can be removed by gel exclusion chromatography, dialysis, or treatment with biobeads. In vitro leakage assays (addition of 50% mouse serum) and in vivo pharmacokinetic studies (in mice) reveal that the A23187/Mn2+ system exhibits superior drug retention over the nigericin/K+ system, and compares favorably with vesicles loaded by the standard DeltapH or amine methods. The unique features of this methodology and possible benefits are discussed.     

Hemodynamics of subarachnoid hemorrhage arrest

Subarachnoid hemorrhage (SAH) causes a spectrum of clinical syndromes from mild discomfort to rapid brain death. The reason for these heterogeneous consequences is poorly understood. A canine autologous shunt model of SAH was used to study this problem. The duration and volume of hemorrhage into the suprasellar cistern at each animal's mean arterial blood pressure were measured at variable hemorrhage flow rates. At high rates of bleeding in seven dogs (18.7 +/- 2.2 ml/min, mean +/- standard deviation), hemorrhage duration was significantly less (191 +/- 116 seconds, p < 0.03) and hemorrhage volume was significantly greater (15.1 +/- 7.0 ml, p < 0.05) than at low flow rates. At low flow rates of bleeding in nine dogs (4.4 +/- 2.2 ml/min), hemorrhage duration was 394 +/- 202 seconds and volume was 10.9 +/- 6.5 ml. Cerebral perfusion pressure (CPP) decreased at all hemorrhage rates but never to 0 mm Hg (perfusion arrest). No correlation between a decrease in CPP and SAH volume or duration was identified. The initial flow rate of SAH had a positive linear correlation with the volume of hemorrhage (23 dogs, r = 0.64, p < 0.01). The data suggest that initial SAH flow rate, and not CPP, has a primary influence on hemorrhage arrest. This finding may influence the clinical rationale for acute management of SAH-induced brain injury.