Search

Two stators of a multistage centrifugal compressor with progressively smaller outer radii have been designed, built, and tested. The aim was to achieve a significant reduction in the outer diameter of the compressor stage without compromising performance. The reduction in size was achieved by reducing the diffusion ratio (outer radius/inner radius) of the vaneless diffuser in two steps. In the first step, the outer diameter of the entire stage was reduced by 8% compared with the baseline design. In the second stage, the outer diameter was reduced by 14%. The outer radius of the smallest design was limited by the impeller exit diameter, which was kept constant, as was the axial length of the stage. The large radius baseline design has been tested on a rotating rig in a 1.5 stage setup. This setup aimed at simulating the multistage behavior by applying a pseudostage upstream of the main stage. The pseudostage consisted of a set of nonrotating preswirl vanes in order to mimic an upstream impeller and was followed by a scaled version of the return channel of the main stage. The experimental database was then used to calibrate a ID analysis code and 3D-computational fluid dynamics methods for the ensuing design and optimization part. By applying an extensive design-of-experiments, the endwalls as well as the vanes of the stator part were optimized for maximum efficiency and operation range. In order to preserve the multistage performance, the optimization was constrained by keeping the circumferentially averaged spanwise flow profiles at the exit of the smaller radius stages within close limits to the original design. The reduced radius designs were then tested in the same 1.5 stage setup as the baseline design. The results indicate that the reduction in size was feasible without compromising the efficiency and operation range of the stage. [ABSTRACT FROM AUTHOR]

We report on the realization of microcavities made of hydrogenated amorphous-Si1-xNx multilayers, with dual-wavelength periodic dielectric mirrors in order to obtain first and second order stop bands. Optical second-harmonic generation with simultaneous resonance for the pump and harmonic waves is demonstrated at finite values of the angle of incidence. The results are in good agreement with a theoretical calculation of the harmonic generation process based on a nonlinear polarization localized at the interfaces between different amorphous layers. [ABSTRACT FROM AUTHOR]

Background: Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) is a valid treatment for hematological oncological or metabolic diseases. Despite its therapeutic efficacy, it is an aggressive treatment that impacts negatively on quality of life (QoL) and may result in Post-Traumatic Stress Disorder (PTSD) symptoms. The aim of this study is to explore rates and risk factors for PTSD symptoms, and fatigue in post-HSCT patients with hematological malignancies., Methods: A total of 123 patients after HSCT were evaluated for PTSD symptoms, QoL and fatigue. PTSD symptoms were assessed with the Impact of Event Scale- Revised (IES-R), QoL was measured with Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT) and fatigue symptoms were assessed with Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F)., Results: A total of 58.54% of the sample developed PTSD symptoms after transplant. Patients with PTSD symptoms reported significantly lower QoL total scores and significantly higher fatigue than those without PTSD symptoms ( p < 0.001). The SEM analysis showed that worse QoL and fatigue affected PTSD symptomatology along different pathways. Fatigue was found as a major influencing factor of PTSD symptoms directly (β = 0.31 **), while QoL only through the mediation of fatigue at a lesser extent. (β = 0.33 *)., Conclusions: Our findings indicate that QoL is a concurrent causative factor to the development of PTSD symptomatology through the mediating role of fatigue. Innovative interventions before transplantation to prevent PTSD symptoms should be investigated to improve survival and QoL in patients.

Introduction: Psychologist's task at the hospital is to take care, from a psychological standpoint, not only of the patient but also of those working at his side, in order to maintain the best possible bio-psycho-social balance and to prevent stress related diseases. The purpose of this study is therefore to assess the stress levels and the coping solutions implemented by doctors and nurses who work closely to severe and difficult diseases such as cancer., Methods: As evaluation tool has been used the Stress and Coping Scale Health Professions (HPSCS). The group used for the research consists of 10 doctors and 34 nurses who work daily at the Hematology Department of Pescara Hospital., Results: According to the answers of the questionnaire it has been possible to highlight that for both doctors and nurses, the most stressful event is the difficult relations with patients. As for the solving attempts, doctors tend to use most frequently the request of social support, while among the nurses also emerge the emotional distress and the avoidance of the problem., Conclusions: The use by the latter of impractical coping strategies, suggests the usefulness of future training programs designed to assist individuals in managing situations that are adverse to the empirical practice.

Temporosphenoidal encephaloceles are rare entities that occur when the temporal lobe herniates into the sphenoid sinus through a skull base defect of the temporal bone. Both an iatrogenic and a traumatic pathogenesis have been proposed. The authors describe a spontaneously occurring temporosphenoidal encephalocele in a 63-year-old woman who had a 4-year history of rhinorrhea. Spiral computerized tomography (CT) scanning revealed a bone defect located inside the ophthalmomaxillary triangle. The intrasphenoidal encephalocele had a heterogeneously hypointense signal compared with cerebrospinal fluid (CSF) on T1-weighted magnetic resonance (MR) images and a hyperintense signal compared with CSF on T2-weighted MR images. Two previous endonasal endoscopic procedures, performed by ear, nose, and throat surgeons, had been unsuccessful. The authors performed an endoscopic endonasal right nostril procedure by using 0 degrees and 45 degrees rigid-lens endoscopes that were 4 mm in diameter and 18 cm long. The encephalocele in the sphenoid sinus was partially removed. DuraGen and fat graft were positioned in the bone defect. Two No. 2 French detachable silicone balloons (1.5 cm3 volume) inflated with surgical glue were introduced into the skull defect and into the sphenoid sinus, respectively. The CSF leakage stopped immediately. No nasal packing or postoperative CSF lumbar drainage was necessary. The patient did well. Postoperative CT and MR imaging, obtained at 24 hours and at 3 months, demonstrated that the balloon and the fat graft filled the bone defect and the sphenoid sinus. Eight months postprocedure no CSF leakage was observed. This appears to be the first case reported in the literature of a temporosphenoidal encephalocele successfully treated by an endoscopic endonasal technique involving packing of the defect with inflated detachable balloons.

This report describes a case of fibrous dysplasia of the skull, involving the right parietal, occipital and temporal bones, with complication caused by entrance of air into the extradural and subcutaneous spaces with intracranial hypertension. This type of complication has never been reported in the literature.

Two different cases of fatal Herpes simplex type 1 encephalitis are reported. A presumptive diagnosis of herpes encephalitis was made on the basis of clinical symptoms and of neurodiagnostic evidence (EEG - CT) and was confirmed by serological and virological tests. The electron microscopy of the nuclei of the infected cells supported the diagnosis of HSV encephalitis.