Antegrade selective cerebral perfusion and moderate hypothermia in aortic arch surgery: clinical outcomes in elderly patients†

OBJECTIVES To evaluate the outcome in elderly patients (≥75 years) undergoing elective aortic arch surgery with the aid of selective antegrade cerebral perfusion (SACP) and moderate hypothermic circulatory arrest (HCA). METHODS A series of 95 patients ≥75 years (median age 77 years, median EuroSCORE 28) undergoing elective aortic arch surgery with SACP and moderate HCA were analysed with regard to clinical outcome. Risk factors for serious adverse events (mortality, neurological injury) were determined. RESULTS Sixty-three patients (66%) underwent ascending aorta and hemiarch replacement, whereas 32 patients (34%) underwent ascending aorta and total arch replacement. Isolated arch replacement was rare. Additionally, 27% of patients underwent aortic valve replacement and 26% underwent root replacement. In-hospital mortality was 7%. Permanent neurological deficits occurred in 5%, transient neurological deficits occurred in 2%. Median SACP time was 24min. Univariate analysis revealed femoral cannulation site (OR: 3.4; CI: 1.25-9.22, P=0.016) as well as HCA ≥40min (OR: 4.21; CI: 1.83-12.58, P=0.001) as predictors of serious adverse events (mortality, neurological injury). CONCLUSIONS Summarizing, elective aortic arch surgery in elderly patients using SACP and moderate HCA provides excellent results regarding mortality and postoperative neurological outcome. Prolonged HCA time and femoral cannulation were the only predictors of serious adverse events (mortality, neurological injury

A current-voltage model for double Schottky barrier devices

Schottky barriers are often formed at the semiconductor/metal contacts and affect the electrical behaviour of semiconductor devices. In particular, Schottky barriers have been playing a major role in the investigation of the electrical properties of mono and two-dimensional nanostructured materials, although their impact on the current-voltage characteristics has been frequently neglected or misunderstood. In this work, we propose a single equation to describe the current-voltage characteristics of two-terminal semiconductor devices with Schottky contacts. We apply the equation to numerically simulate the electrical behaviour for both ideal and non-ideal Schottky barriers. The proposed model can be used to directly estimate the Schottky barrier height and the ideality factor. We apply it to perfectly reproduce the experimental current-voltage characteristics of ultrathin molybdenum disulphide or tungsten diselenide nanosheets and tungsten disulphide nanotubes. The model constitutes a useful tool for the analysis and the extraction of relevant transport parameters in any two-terminal device with Schottky contacts

Long term recurrence of solitary fibrous tumor involving vertebral body in thoracic spine. A case report

Solitary fibrous tumor (SFT) represents only 0.08% of all primary bone tumors and 0.1% of primary malignant bone tumors and rarely occurs in the spine. We present the case of a 56-year-old woman with long term recurrence (11 years) of spinal SFT involving T8 vertebral body. We performed a total resection of the lesion and spinal fusion T6-T11 with T8 titanium mesh and placement of pedicle screws in T6-T7 and T10-T11 connected by rods. Microscopic examination confirmed the recurrence of the WHO grade II solitary fibrous tumor. SFT is known for a late but common recurrence and uncertain behaviour. Gold standard treatment is Gross Total Resection. We believe that when vertebral bone is involved it is essential to perform a total excision with "supracomplete" resection if possible in order to avoid local recurrence, more difficult to treat due to an higher rate of perioperative complications. Periodical long-term follow-up is essential to allow early detection of relapses and to allow long-term survival

Field emission from two-dimensional GeAs

GeAs is a layered material of the IV-V groups that is attracting growing attention for possible applications in electronic and optoelectronic devices. In this study, exfoliated multilayer GeAs nanoflakes are structurally characterized and used as the channel of back-gate field-effect transistors. It is shown that their gate-modulated p-type conduction is decreased by exposure to light or electron beam. Moreover, the observation of a field emission current demonstrates the suitability of GeAs nanoflakes as cold cathodes for electron emission and opens up new perspective applications of two-dimensional GeAs in vacuum electronics. Field emission occurs with a turn-on field of ~80 V/{\mu}m and attains a current density higher than 10 A/cm^2, following the general Fowler-Nordheim model with high reproducibility.Comment: 10 pages, 3 figure

Governing Consensus. The Political Use of Knowledge in Italy

How were political scenarios opened up by the revolutionary era navigated? This volume investigates how expertise emerged as a vital political resource in the Italian peninsula between 1789 and 1870, a time of revolution and institutional upheaval. Moving beyond the familiar categories of charisma and celebrity, it explores the political role of knowledge by focusing on places of education, media events, agents and texts. Framing Italy as a laboratory of early modern politics, this volume examines how the reworking of traditional knowledge and the rise of new forms of expertise enabled individuals to act effectively in the public sphere, influence society and navigate the shifting landscape of power, ultimately governing consensus and securing lasting authority

The Influence of Insertion Torque on Stress Distribution in Peri-Implant Bones Around Ultra-Short Implants: An FEA Study

Using ultra-short dental implants is a promising alternative to extensive bone grafting procedures for patients with atrophic posterior mandibles and vertical bone loss. However, the amount of insertion torque (IT) applied during implant placement significantly influences stress distribution in the peri-implant bone, which affects implant stability and long-term success. Materials and Methods: This study used finite element analysis (FEA) to examine how different insertion torques (35 N·cm and 75 N·cm) affect stress distribution in cortical and trabecular bone types D2 and D4 surrounding ultra-short implants. Von Mises equivalent stress values were compared with ultimate bone strength thresholds to evaluate the potential for microdamage during insertion. Results: The findings demonstrate that increasing IT from 35 N·cm to 75 N·cm led to a significant increase in peri-implant bone stress. Specifically, cortical bone stress in D4 bone increased from approximately 79 MPa to 142 MPa with higher IT, exceeding physiological limits and elevating the risk of microfractures and bone necrosis. In contrast, lower IT values kept stress within safe limits, ensuring optimal primary stability without damaging the bone. These results underscore the need to strike a balance between achieving sufficient implant stability and avoiding mechanical trauma to the surrounding bone. Conclusions: Accurate control of insertion torque during the placement of ultra-short dental implants is crucial to minimize bone damage and promote optimal osseointegration. Excessive torque, especially in low-density bone, can compromise implant success by inducing excessive stress, thereby increasing the risk of early failure

Finite element analysis of primary healing implants with different transmucosal designs

Purpose: This study aimed to assess the response of peri-implant tissues, both hard and soft, to mechanical stress when using a primary healing implant (PHI) with two different transmucosal profiles: concave (Model A) and divergent (Model B). The investigation also sought to observe bone modeling under post-extraction conditions. Materials and methods: The methodology involved the creation of a three-dimensional bone model of the first molar region, derived from a computed tomography scan. Subsequently, two implants were inserted into the bone site and subjected to a loading force of 100 N at a 45° angle. Results: The results of stress analysis, using the von Mises criterion, indicated that Model A exhibited a more uniform stress distribution within the soft tissues, registering a maximum value of 75 MPa, in contrast to 126 MPa observed in Model B. Concerning implant stress, the peak value was recorded at the conometric connection zone between the implant and the abutment, measuring 138 MPa for Model B and 125 MPa for Model A. The study specifically analyzed cortical bone stress, which revealed levels of 72 MPa for Model B and 64 MPa for Model A. Additionally, stress distribution in immature bone ranged from 1.3 to 9 MPa for Model A and from 1.5 to 12 MPa for Model B. Conclusions: The finite element method represents a valuable tool for the design and optimization of implant shapes, taking into account occlusal loads and specific anatomical locations. This approach aims to enhance the stimulation of both soft and hard tissues, thereby mitigating the risk of implant failure

Characterization of the electric transport properties of black phosphorous back-gated field-effect transistors

We use thin layers of exfoliated black phosphorus to realize back-gated field-effect transistors in which the Si/SiO2 substrate is exploited as gate electrode. To prevent the detrimental effect of the air exposure the devices are protected by Poly(methyl methacrylate). We report the observation of an improved contact resistance at the interface between the layered material and the metal contact by electrical conditioning. We also demonstrate the existence of a hysteresis in the transfer characteristics that improves by increasing the gate voltage sweep range. Finally, we prove the suitability of such transistors as memory devices

The ARCH Projects: design and rationale (IAASSG 001)

OBJECTIVE A number of factors limit the effectiveness of current aortic arch studies in assessing optimal neuroprotection strategies, including insufficient patient numbers, heterogenous definitions of clinical variables, multiple technical strategies, inadequate reporting of surgical outcomes and a lack of collaborative effort. We have formed an international coalition of centres to provide more robust investigations into this topic. METHODS High-volume aortic arch centres were identified from the literature and contacted for recruitment. A Research Steering Committee of expert arch surgeons was convened to oversee the direction of the research. RESULTS The International Aortic Arch Surgery Study Group has been formed by 41 arch surgeons from 10 countries to better evaluate patient outcomes after aortic arch surgery. Several projects, including the establishment of a multi-institutional retrospective database, randomized controlled trials and a prospectively collected database, are currently underway. CONCLUSIONS Such a collaborative effort will herald a turning point in the surgical management of aortic arch pathologies and will provide better powered analyses to assess the impact of varying surgical techniques on mortality and morbidity, identify predictors for neurological and operative risk, formulate and validate risk predictor models and review long-term survival outcomes and quality-of-life after arch surger