Specifically designed samples have been analyzed to test the ability of Brillouin spectroscopy to provide reliable mechanical characterization of micro and nano-objects. The selected samples are ...polymeric films, whose transversal sizes from hundreds of nano- to some micro-meters cover the entire range of length-scales relevant in Brillouin scattering process. The experimental data highlight how, the size of the extended collective oscillation (acoustic phonons, in brief) is the lowest spatial resolution reachable in Brillouin mechanical characterization. Conversely, in the limit condition of phonon confinement, the technique provides the mechanical properties of nano-objects whose characteristic size is comparable with the phonon wavelength (⁓300 nm). Investigating acoustically heterogeneous materials, both size of heterogeneity and acoustic mismatch between adjacent regions are shown to be relevant in shaping the Brillouin response. In particular, a transition from a confined to a non-confined condition is obtained modulating the acoustic mismatch between the micro-objects and their local environment. The provided results and the derived analytic models for the data analysis will guide the interpretation of Brillouin spectra acquired in complex nano-structured samples such as cells, tissues or biomimetic materials. Our analysis can therefore generate new insights to tackle fundamental problems in mechanobiology or to characterize new bioengineered materials.
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•Thin films of different traversals size are investigated as biomaterials models.•Brillouin spectroscopy measures the mechanical properties of micro and nano-objects.•Phonon confinement increases the spatial resolution of Brillouin spectroscopy.•Size and acoustic mismatch of heterogeneities alters Brillouin elastography.
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•Kinetic micellar effects on SN2 reactions were investigated in the range 25–45°C.•The kinetic data were quantitatively analysed by the pseudophase model.•The activation parameters ...were evaluated from the Eyring equation.•The nature of halide ion influences the kinetic temperature effect in micellar media.•The surfactant head group size influences the temperature effect in micellar media.
Reactivity of methyl naphthalene-2-sulphonate, MeONs, with H2O, Br− and Cl− in water and in cationic micelles of cetyltrialkylammonium surfactants, n-C16H33N+R3X−, R=Me (CTA+), n-Pr (CTPA+), X=Br, Cl, CH3SO3, has been investigated in the temperature range 25–45°C. Micellar rate effects were analysed by using the pseudophase treatment, and the second-order rate constants in the micellar pseudophase were evaluated at the various temperatures. Values of these rate constants increase with temperature, and the effect is less important in micelles than in water and more important for chloride than for bromide ions. Micelles lead to an ion behaviour discrimination, whose extent depends on surfactant type and on temperature, with maximum effect in CTPA+ at 25°C and with bromide being always more reactive than chloride.
Quantitative analysis of the temperature effect by the Eyring equation showed that micelles speed up reaction of MeONs with halide ions by decreasing the activation enthalpies, which is partially offset by decreases in the activation entropies. The rate acceleration by increase in surfactant head group size has only enthalpic origin for bromide and only entropic origin for chloride: this different behaviour was rationalised taking into account both solvation of anions and the hydrophobic effect.
Study Design:
Retrospective multicenter.
Objectives:
diffuse idiopathic skeletal hyperostosis (DISH) involving the cervical spine is a rare condition determining disabling aero-digestive symptoms. We ...analyzed impact of preoperative settings and intraoperative techniques on outcome of patients undergoing surgery for DISH.
Methods:
Patients with DISH needing for anterior cervical osteophytectomy were collected. Swallow studies and endoscopy supported imaging in targeting bone decompression. Patients characteristics, clinico-radiological presentation, outcome and surgical strategies were recorded. Impact on clinical outcome of duration and time to surgery and different surgical techniques was evaluated through ANOVA.
Results:
24 patients underwent surgery. No correlation was noted between specific spinal levels affected by DISH and severity of pre-operative dysphagia. A trend toward a full clinical improvement was noted preferring the chisel (P = 0.12) to the burr (P = 0.65), and whenever C2-C3 was decompressed, whether hyperostosis included that level (P = 0.15). Use of curved chisel reduced the surgical times (P = 0.02) and, together with the nasogastric tube, the risk of complications, while bone removal involving 3 levels or more (P = 0.04) and shorter waiting times for surgery (P < 0.001) positively influenced a complete swallowing recovery. Early decompressions were preferred, resulting in 66.6% of patients reporting disappearance of symptoms within 7 days. One and two recurrences respectively at clinical and radiological follow-up were registered 18-30 months after surgery.
Conclusion:
The “age of DISH” counts more than patients’ age with timeliness of decompression being crucial in determining clinical outcome even with a preoperative mild dysphagia. Targeted bone resections could be reasonable in elderly patients, while in younger ones more extended decompressions should be preferred.
The coronavirus disease 2019 (COVID-19) pandemic is a worldwide medical challenge due to the scarcity of proper information and remedial resources. The ability to efficiently avoid a further ...SARS-CoV-2 pandemic will, therefore, depend on understanding several factors which include host immunity, virus behavior, prevention measures, and new therapies. This is a multi-phase observatory study conducted in the SG Moscati Hospital of Taranto in Italy that was converted into COVID-19 Special Care Unit for SARS-Co-V2 risk management. Patients were admitted to the 118 Emergency Pre-Hospital and Emergency Department based on two diagnostic criteria, the nasopharyngeal swab assessed by reverse-transcriptase-polymerase-chain-reaction (RT-PCR) and CT-scan image characterized by ground glass opacity. Patients were divided into four groups, positive-positive (ER-PP), negative-positive (ER-NP), negative-negative (ER-NN) and a group admitted to the ICU (ER-IC). A further control group was added when the T and B lymphocyte subsets were analyzed. Data included gender, age, vital signs, arterial blood gas analysis (ABG), extensive laboratory results with microbiology and bronchoalveolar lavage fluid (BALF) which were analyzed and compared. Fundamental differences were reported among the groups. Males were significantly higher in PP, ICU, and NP groups, from 2 to 4-fold higher than females, while in the NN group, the number of females was mildly higher than males; the PP patients showed a marked alkalotic, hypoxic, hypocapnia ABG profile with hyperventilation at the time of admission; finally, the laboratory and microbiology results showed lymphopenia, fibrinogen, ESR, CRP, and eGFR were markedly anomalous. The total number of CD4+ and CD8+ T cells was dramatically reduced in COVID-19 patients with levels lower than the normal range delimited by 400/μL and 800/μL, respectively, and were negatively correlated with blood inflammatory responses.
Tissue temperature distribution plays a crucial role in the outcome of laser-induced thermotherapy (LITT), a technique employed for neoplasias removal. Since recent studies proposed LITT for ...pancreatic tumors treatment, assessment of temperature and of its effects around the laser applicator could be useful to define optimal laser settings. The aims of this work are temperature monitoring and measurement of ablated tissue volume in an ex vivo porcine pancreas undergoing double-applicator LITT. A three-dimensional numerical model is implemented to predict temperature rise and volumes of ablated tissue in treated pancreas. Experiments are performed to validate the model, with two modalities: (1) 12-fiber Bragg grating sensors are adopted to monitor the heating and cooling during LITT at several distances from the applicators tip, and (2) 1.5-T MR imaging is used to estimate the ablated volume. Experimental data agree with theoretical ones: at 2 mm from both applicators tips, the maximum temperature increase is approximately 60 °C downward from the tips, while it increases of about 40 °C and 30 °C, respectively, at the level and upward from the tips. This behavior occurs also at other distances, proving that the tissue downward from the tip is mostly heated. Furthermore, the estimated volume with MRI agrees with theoretical one (i.d., 0.91 ± 0.09 vs. 0.95 cm
3
). The encouraging results indicate that the model could be a suitable tool to choose the optimal laser settings, in order to control the volume of ablated tissue.
The iron loading of catalysts, supported on SiO₂, was investigated between 10 and 75 wt%, with and without the addition of promoters (K and Cu), in order to highlight the different catalytic ...performances of the samples in the Fischer-Tropsch synthesis. An optimization study of the prepared catalysts (active metal/promoters ratio, catalysts' activation procedure before the Fischer-Tropsch runs, influence of the feeding gas composition) is reported. The mechanical resistance of the catalysts was also evaluated using a suitable method involving ultrasound.
Abstract Governmental and private companies in the New Space Economy collaborate to realise valuable space products and services, yet this partnership raises sustainability concerns. This study ...investigates whether and how space companies address social and environmental aspects in their collaborative activities. Focusing on the launch service segment in Europe and the USA, we conducted a content analysis of financial and non‐financial reports and websites by using the legitimacy theory framework. This study reveals that space companies emphasise the positive social and environmental impacts of their collaboration while providing limited information on potential drawbacks. They extensively outline measures to mitigate social and environmental damages, aiming to present a favourable image of their activities. This research contributes to fostering the debate on social and environmental accounting and accountability of space actors. It sheds light on how they report on sustainability aspects offering insights into the legitimacy strategies they use and promoting their accountability.
Supported iron-based Fischer–Tropsch (FT) catalysts with high loading of active metal have been prepared using both traditional and innovative methods. In these latter the impregnation of silica ...support has been performed by adding a step involving an ultrasound (US) or a microwave (MW) treatment to improve the metal deposition and to increase the catalyst activity. FT results have indicated the catalysts prepared by US as the most efficient, particularly when sonication is performed in argon atmosphere. MW prepared samples have given results very similar to those obtained with the traditional method. In order to explain the different catalytic activity, all the samples have been characterized by BET, TPR, SEM, TEM, XRD and micro-Raman analyses.
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