Study of the Electron Beam Melting Process Parameters' Influence on the Tensile Behavior of 3D Printed Ti6Al4V ELI Alloy in Static and Dynamic Conditions.

The Ti6Al4V alloy is widely adopted in many high-end applications in different fields, including the aerospace, biomechanics, and automotive sectors. Additive manufacturing extends its range of possible applications but also introduces variations in its mechanical performance, depending on the whole manufacturing process and the related control parameters. This work focuses on the detailed tensile stress-strain characterization at low and high strain rates of a Grade 23 Ti alloy manufactured by electron beam melting (EBM). In particular, the main aim is to study the effect of the variation of the EBM process parameters on the performance of the material and their consequent optimization in order to obtain the best printed material in terms of ductility and strength. The adopted optical experimental setups allow the semi-local scale analysis of the neck section which makes possible the accurate estimation of stress, strain, and strain rate, all over the post-necking range and up to the very incipient specimen failure. Among the EBM printing process parameters, the speed function was previously identified as the one mainly affecting the material performance at static rates. Therefore, two different parameter sets, corresponding to the standard value and to an optimized value of the speed function parameter, respectively, are tested here at dynamic rates of 1, 15, and 700 s-1, for assessing the effect of the speed function on the dynamic material response. The results show that the optimized parameter set has a better performance compared to the standard one in terms of strength and ductility. In particular, in both static and dynamic conditions, it presents an increase of the true stress-strain curve (about 5% on average) and an increase of the failure strain (about 11% on average). Moreover, in respect to the standard parameter set, the optimized one is also characterized by a huge increase of the amplification due to the strain rate (about 49% on average for the considered strain rates).

Multimodal Simulation of a Novel Device for a Safe and Effective External Ventricular Drain Placement.

BACKGROUND: External ventricular drain (EVD) placement is mandatory for several pathologies. The misplacement rate of the EVD varies widely in literature, ranging from 12.3 to 60%. The purpose of this simulation study is to provide preliminary data about the possibility of increasing the safety of one of the most common life-saving procedures in neurosurgery by testing a new device for EVD placement. METHODS: We used a novel guide for positioning the ventricular catheter (patent RM2014A000376). The trajectory was assessed using 25 anonymized head CT scans. The data sets were used to conduct three-dimensional computer-based and combined navigation and augmented reality-based simulations using plaster models. The data set inclusion criteria were volumetric head CT scan, without midline shift, of patients older than 18. Evans' index was used to quantify the ventricle's size. We excluded patients with slit ventricles, midline shift, skull fractures, or complex skull malformations. The proximal end of the device was tested on the cadaver. RESULTS: The cadaveric tests proved that a surgeon could use the device without any external help. The multimodal simulation showed Kakarla grade 1 in all cases but one (grade 2) on both sides, after right and left EVD placement. The mean Evans' index was 0.28. The geometric principles that explain the device's efficacy can be summarized by studying the properties of circumference and chord. The contact occurs, for each section considered, at the extreme points of the chord. Its axis, perpendicular to the plane tangent to the spherical surface at the entry point, corresponds to the direction of entry of the catheter guided by the instrument. CONCLUSION: According to our multimodal simulation on cadavers, 3D computer-based simulation, 3D plaster modeling, 3D neuronavigation, and augmented reality, the device promises to offer safer and effective EVD placement. Further validation in future clinical studies is recommended.

Effectiveness and Safety of A Nutraceutical Formulation for the Treatment of Functional Dyspepsia in Primary Care.

BACKGROUND: Although FD may affect up to 10% of the general population, the therapy for FD is not standard. Recently, ginger-based food supplements have been proposed in order to restore FD symptoms. Our aim was to assess the efficacy of a new nutraceutical formulation containing extract of gingerol and thymus as a possible natural treatment in managing the symptoms of functional dyspepsia (FD). METHODS: We retrospectively analyzed the efficacy and safety profiles of a nutraceutical formulation containing Zingiber officinalis root extract and a standardized Thymus extract. It was administered as 1 ml/day twice a day for 90 days. Patients were assessed at baseline and after 1, 2 and 3 months of treatment, following a month of pharmacological washout by completing a questionnaire reporting the trend of the following symptoms: epigastric pain, epigastric heaviness, early satiety, belching, and regurgitation. Every symptom was assessed by a Visual Analogic Scale (VAS), ranging from 0= absence to 10= maximal severity. RESULTS: We enrolled 272 patients (99 males and 173 females; median IQR age 49.5, 36-64 yrs). Obesity (BMI>30) was present in 28 (12.5%) patients; smokers were 83 (30.5%); and comorbidities were present in 107 (39.3%) patients. Improvement of symptom scores during treatment and one month after its suspension was extremely significant (p<0.000). CONCLUSION: This large study found that nutraceutical formulation could be one of the tools for an empirical approach to treat patients with FD, especially when a non-conventional drug treatment is preferable for the patient and considered suitable by the physician.

Capsule endoscopy is useful and safe for small-bowel surveillance in familial adenomatous polyposis.

BACKGROUND: Duodenal cancer and ampullary cancer are major causes of death after a prophylactic colectomy in patients with familial adenomatous polyposis (FAP). Forward-viewing endoscopy and side-viewing endoscopy are recommended in patients with FAP for surveillance of periampullary and duodenal polyposis. The study of polyps distal to the duodenum in FAP is limited. A capsule endoscopy (CE) allows visualization of the mucosa of the entire small bowel. OBJECTIVE: The objective was to detect whether CE has clinical value or any utility for the surveillance of small-bowel polyps in patients with FAP and to evaluate whether there are genotypic factors that predict which patients are at a lower risk of small-bowel polyps. SETTING: Two Italian tertiary-referral centers. PATIENTS: Twenty-three patients with FAP who presented for a CE. MAIN OUTCOME MEASUREMENTS: Patients with FAP were examined by CE to assess the location, size, and number of small-bowel polyps. Patient age at CE, sex, years of observation after surgery, type of surgery, duodenal adenomas, and colorectal cancer at surgery were analyzed. All patients were selected for mutation analysis, and the germline adenomatous polyposis coli (APC) gene mutation was detected. RESULTS: Eleven of 23 patients with FAP had duodenal polyps. During CE, jejunal-ileal polyps were detected in 7 of 23 FAPs, with a total number of 15 polyps in the ileum. The presence of duodenal adenomas was the only clinical feature predictive of small-bowel polyps. Identification of the ampulla of Vater was not achieved with CE; duodenal polyps were only seen in 4 of 11 patients identified endoscopically, with an underestimation of polyp numbers. APC mutations between codons 499 and 805 were associated with the absence of small-bowel polyps. CONCLUSIONS: CE is useful and safe for the surveillance of jejunal-ileal polyps in selected patients with FAP. CE is not useful in the surveillance of the duodenum where the majority of small-bowel cancers occur.

Prevalence and clinical associations of prolonged prothrombin time in adult untreated coeliac disease.

INTRODUCTION: Untreated coeliac disease may induce malabsorption of many nutrients. It may also induce vitamin K deficiency, which causes prolongation of the prothrombin time. The aim of the present study was to evaluate the prevalence and associations of prolonged prothrombin time in a series of coeliac adults. METHODS: We carried out a cross-sectional analysis of data collected on 390 adults with untreated coeliac disease diagnosed from January 1997 to December 2000. Prolonged prothrombin time was defined as INR > or = 1.4. RESULTS: A prolonged prothrombin time was found in 72 coeliac patients (18.5%). Parenteral vitamin K therapy was required in 5.6% of patients. Patients with prolonged prothrombin time had significant lower values of haemoglobin, iron, proteins, cholesterol and serum aspartate transaminase, and significantly higher prevalence of diarrhoea, weight loss, abdominal pain and low bone mineral density in comparison with patients with normal prothrombin time. However, low bone density was present in 11.6% of patients with normal INR. A prolonged prothrombin time was only found in a few patients with subclinical coeliac disease (0.9%). CONCLUSIONS: Data indicate that the prevalence of prolonged prothrombin time is about 20% in a large series of adult untreated coeliac patients. A prolonged prothrombin time was significantly related to all the markers of severe malabsorption, including low mineral density. Our suggestion is that vitamin K related proteins may also play a role in determining or worsening calcium homeostasis disorders in coeliac disease. The very low prevalence of coagulation disorders in subclinical coeliac disease indicates that there is no need to screen for coeliac disease in patients with isolated coagulation disorders.