Machine learning applied to X-ray tomography as a new tool to analyze the voids in RRP Nb3Sn wires.

The electro-mechanical and electro-thermal properties of high-performance Restacked-Rod-Process (RRP) Nb3Sn wires are key factors in the realization of compact magnets above 15 T for the future particle physics experiments. Combining X-ray micro-tomography with unsupervised machine learning algorithm, we provide a new tool capable to study the internal features of RRP wires and unlock different approaches to enhance their performances. Such tool is ideal to characterize the distribution and morphology of the voids that are generated during the heat treatment necessary to form the Nb3Sn superconducting phase. Two different types of voids can be detected in this type of wires: one inside the copper matrix and the other inside the Nb3Sn sub-elements. The former type can be related to Sn leaking from sub-elements to the copper matrix which leads to poor electro-thermal stability of the whole wire. The second type is detrimental for the electro-mechanical performance of the wires as superconducting wires experience large electromagnetic stresses in high field and high current conditions. We analyze these aspects thoroughly and discuss the potential of the X-ray tomography analysis tool to help modeling and predicting electro-mechanical and electro-thermal behavior of RRP wires and optimize their design.

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route.

The upper critical field sets the thermodynamic limit to superconductivity. A big gap is present between the upper-critical-field values measured in MgB2 polycrystalline bulk superconductors and those of thin films, where values as high as ~ 50 T have been achieved at 4.2 K. Filling this gap would unlock the potential of MgB2 for magnet applications. This work presents the results of an extensive experimental campaign on MgB2 bulk samples, which has been guided by a Design of Experiment. We modeled the dependence of the upper critical field on the main synthesis parameters and established a new record (~ 35 T at 4.2 K) preparing C-doped bulk samples by a non-conventional rapid-synthesis route. This value appears to be an upper boundary for the upper critical field in bulk samples. Structural disorder in films seems to act selectively on one of the two bands where superconductivity in MgB2 takes place: this enhances the upper critical field while reducing the critical temperature only by few Kelvins. On the other hand, the critical temperature in bulk samples decreases monotonically when structural disorder increases, and this imposes a limit to the maximum achievable upper critical field.

Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading.

Understanding the critical current performance variation of Nb3Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation between the void morphology and the electro-mechanical limits measured on different Bronze route Nb3Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires' void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Finally, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation upon mechanical loading.

Effect of bariatric surgery on peripheral flow-mediated dilation and coronary microvascular function.

BACKGROUND AND AIMS: To assess the effects of bariatric surgery (BS) on peripheral endothelial function and on coronary microvascular dilator function. METHODS AND RESULTS: We studied 50 morbidly obese patients (age 38 ± 9, 13 M) who underwent BS and 20 comparable obese controls (age 41 ± 11, 6 M) without any evidence of cardiovascular disease. Peripheral vascular dilator function was assessed by brachial artery diameter changes in response to post-ischemic forearm hyperaemia (flow-mediated dilation, FMD). Coronary microvascular function was assessed by measuring coronary blood flow (CBF) velocity response to i.v. adenosine and to cold pressor test (CPT) in the left anterior descending coronary artery by transthoracic Doppler echocardiography. The tests were performed at baseline and at 3-month follow-up. At baseline, FMD and CBF response to adenosine and CPT were similar in the 2 groups. Compared to baseline, FMD at follow-up improved significantly in BS patients (5.9 ± 2.7% to 8.8 ± 2.4%, p < 0.01), but not in controls (6.3 ± 3.2% vs. 6.4 ± 3.1%, p = 0.41). Similarly, a significant improvement of CBF response to adenosine (1.63 ± 0.47 to 2.45 ± 0.57, p < 0.01) and to CPT (1.43 ± 0.26 to 2.13 ± 0.55, p < 0.01) was observed in BS patients but not in controls (1.55 ± 0.38 vs. 1.53 ± 0.37, p = 0.85; and 1.37 ± 0.26 vs. 1.34 ± 0.21, p = 0.48, respectively). The favourable vascular effects of BS were similar independently of the presence and changes of other known cardiovascular risk factors and of basal values and changes of serum C-reactive protein levels. CONCLUSIONS: Our data show that, in morbidly obese patients, together with peripheral endothelial function, BS also improves coronary microvascular function. These effects suggest global improvement of vascular function which can contribute significantly to the reduction of cardiovascular risk by BS reported in previous studies.

Single-incision laparoscopic cholecystectomy: surgery without a visible scar.

Laparoscopic cholecystectomy has been recognized since 1992 as the gold standard procedure for gallbladder surgery. The authors propose a single-incision laparoscopic (SILS) cholecystectomy as a step toward less invasive surgical procedures. A single intraumbilical 12-mm incision is made, and the umbilicus is pulled out, exposing the fascia. Pneumoperitoneum is induced with the Versastep Veress access needle. A 5-mm trocar then is introduced, and the abdominal cavity is explored with a 5-mm 30 degrees optic. Second and third trocars are introduced respectively at the left and right sides, near the first trocar. Two sutures are used to suspend the gallbladder and to ensure optimal exposure of the Triangle of Calot. Dissection is performed as a normal retrograde cholecystectomy using an Endoshear roticulator in the left trocar and an Endograsp roticulator in the right hand. The cystic artery and cystic duct are clipped separately with a standard 5-mm clip applier and then excised. The gallbladder is removed through the umbilical incision. Of the 12 patients who underwent SILS cholecystectomy without major complications, 8 had previously undergone other laparoscopic surgeries. The body mass index (BMI) exceeded 35 in three cases. Operative time decreased and stabilized from the first 3-h SILS cholecystectomy to approximately 50 min after the first five cases. At this writing, the authors find SILS cholecystectomy to be feasible, safe, and effective.

Laparoscopic resection with intraoperative radiotherapy: a new step in the multimodal treatment of advanced colorectal cancer.

BACKGROUND: Local recurrence is one of the most important problems related to resection of rectal cancer in locally advanced cases (T3-T4). Total mesorectal excision (TME) is the mainstay of surgical therapy, although many articles have been published about the availability of intraoperative radiotherapy (IORT) for the control of locally advanced rectal cancers. METHODS: The authors describe six patients affected by advanced rectal cancer (T3N1) whom they treated with neoadjuvant radiochemotherapy and laparoscopic rectal resection combined with TME and IORT. RESULTS: The operative time did not exceed 6 h in any case with IORT treatment. The procedure itself and the transfer of patients to the radiotherapy room accounted for about 2 h. The postoperative course was uneventful in every case, and all the patients were discharged within the first 8 postoperative days. CONCLUSIONS: This report describes the technical aspect and the feasibility of IORT associated with laparoscopic surgical resection for rectal cancer.

[Duodenocephalopancreatectomy with pylorus sparing and occlusion of the main bile duct with fibrin glue]. / Duodenocefalopancreasectomia con conservazione del piloro e occlusione del dotto pancreatico principale con fibrin glue.

The leakage of pancreaticojejunostomy represents the main technical post-operative complication after pancreaticoduodenectomy. Because pancreatic fistula can be the source of morbidity and mortality and it is related to the integrity of the pancreatic-enteric anastomosis, a number of technical modification have been suggested, including pancreaticojejunostomy, pancreaticogastrostomy and occlusion of the main pancreatic duct with fibrin glue. The incidence of leakage is particularly high in case of narrow ducts and tender pancreatic glands; in such conditions some experiences in literature suggest the technique of occlusion of the main pancreatic duct with fibrin glue.

[Total gastrectomy extended to the head of the pancreas and the liver with D4 lymphadenectomy for well-differentiated gastric carcinoma]. / Gastrectomia totale estesa alla testa del pancreas e al fegato con linfoadenectomia D4 per carcinoma gastrico ben differenziato.

Adenocarcinoma of the stomach is the second most common cancer worldwide. Early diagnosis and an adequate surgical approach could save live. Surgical approach is conditioned by the extension of the disease and the presence of metastases. Extended lymph-node dissection (D2) has been generally accepted as a standard treatment modality. However, the role of the super-extended lymphadenectomy (D4) for gastric cancer has not been established.

Osteoid osteoma of the femur with a double nidus: a case report.

Osteoid osteoma is a common benign lesion, that occurs in children and young adults. The authors report the observation of a multifocal lesion which is infrequently reported in the literature. S.A., a 10-year-old female came to our observation complaining of spontaneous pain in her right hip and cruralgia radiating to the homolateral knee over the last 6 months; the symptoms, which increased during the night, were relieved by treatment with NSAIDS. Clinical examination and imaging studies confirmed a diagnosis of osteoid osteoma with a double nidus; the lesion was treated by CT-guided thermo-ablation with radiofrequency under general anaesthesia. Complete regression of symptoms was observed at 2-year follow-up.

Memory distortion during acute and chronic pain recalling.

AIM: The aim of this study was to evaluate the presence of pain memory distorsion using different quantitative pain scales. METHODS: A retrospective study on 2333 patients treated in a Pain Therapy Centre from 1994 to 2000 was carried out. VAS and NRS scores have been evaluated, as referred by patients, at the beginning and at the end of treatment. Moreover pain relief has been evaluated by means of correlation between initial and final pain. RESULTS: Patients do not remember initial pain correctly, using both VAS and NRS. CONCLUSION: Pain memory distorsion is related to pain intensity variation during treatment rather than present pain, and it is inversely related to the initial pain intensity. For this reason, it is not correct to evaluate pain relief at the end of treatment since this procedure can under- or over-estimate the initial pain.

Colorectal cancer: obstruction is an independent negative prognostic factor after radical resection.

The rate of colorectal tumors causing large bowel obstruction is still high (about 16%). In our experience, 93 out of 985 patients (9.4%) affected by colorectal cancer required surgery because of large bowel obstruction. The comparative analysis between 64 (68.8%) obstructed and 738 (82.7%) non-obstructed radically resected patients showed that sex and age of patients, tumor site, tumor diameter, parietal infiltration, grading, lymphnode involvement, distant metastases, and staging were not significantly different. Post-operative mortality rates (1.6% vs. 0.5%) and morbidity rates (15.6% vs. 15.6%) were not significantly different as well. On the contrary, survival rate was different. Patients submitted to radical resections had a far poorer prognosis as compared with non-obstructed radically resected ones: the five-year survival was 41.2% and 78.9% respectively. Radically resected obstructed patients showed an higher and earlier ráte of local and distant recurrence with a disease-related death rate of 47.6% vs. 16.3% as compared with non-obstructed ones. The occlusive phenomenon by itself resulted to represent an independent unfavorable factor negatively affecting long term prognosis after radical resections.

Gastric cancer in the elderly.

Nowadays an increased number of elderly patients undergo surgery for gastric cancer. The old age by itself does not seem to represent a prohibitive risk factor anymore. Two groups of patients operated on of gastric cancer at our surgical unit (Group A = 378 patients younger or as old as 65 years and Group B = 330 patients older than 65 year) were compared. There were not statistically significant differences between the two groups in terms of number of performed radical exereses (57.7% vs. 42.3% respectively), kind of resective operation (total gastrectomy or subtotal gastrectomy) and extent of lymphadenectomy (D2-D3 type: 64.7% vs 63.8% respectively). The location of tumor, the distribution by stage and the long term survival of radically resected cases were not statistically different in the two groups of patients. Five-year survival after radical resection was 56.8% and 54.0% respectively. We conclude that elderly patients in good clinical conditions affected by gastric cancer should undergo radical resection with lymphadenectomy such extensive as D2-D3 type.