Molecular Dynamics Study of Self-Diffusion in Zr

We employed a recently developed semi-empirical Zr potential to determine the diffusivities in the hcp and bcc Zr via molecular dynamics simulation. The point defect concentration was determined directly from MD simulation rather than from theoretical methods using T=0 calculations. We found that the diffusion proceeds via the interstitial mechanism in the hcp Zr and both the vacancy and interstitial mechanisms give contribution in diffusivity in the bcc Zr. The agreement with the experimental data is excellent for the hcp Zr and for the bcc Zr it is rather good at high temperatures but there is a considerable disagreement at low temperatures

Implementation of Project Activities in the System of StudentCentered Learning

The article addresses the educational project activities implementation at universities as part of the student-centered learning and a means to raise the effectiveness of students’ professional training. The article provides a critical comparison of the basic elements and features of project activities and SCL. The author proposes a three-tier system of teacher – student – teacher and a methodology for project activities implementation, taking into account the basic principles of SCL. In accordance with the developed system, at the first stage, the teacher organizes the student’s activities on the project including his/her discussing the topic, problem, goal, determining their own requirements for the implementation of the project and individual tasks. At the second stage, the methodology determines the organization of students’ self-governing work on the project, taking into account their personal qualities and experience. An active management of self-governing work enables to build an individual educational trajectory of a student, guide his/her personal development. At the third stage, the methodology determines the teacher’s activities to foster mastering the competencies by the students. These activities are necessarily based on partnership interaction and exchange of views between the teacher and students, the student’s personal critical assessment of the project results and its comparison with the work of other students. The author suggests to positively evaluate incomplete or erroneous results in case the way and method to achieve the assigned tasks were correct and use transparent, objective and understandable for students criteria in assessing the results of his work

Acute mesenterial ischemia: optimal diagnosis and treatment modality

Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Introducere: La momentul actual nu există criterii şi principii desăvârşite pentru diagnosticarea şi tratamentul ischemiei mezenteriale acute bazate pe probe controlate ştiințific, iar rezultatele tratamentului acestor pacienți este nesatisfăcător. Rata mortalității la acest grup de pacienți variază de la 70-90%. Scopul: aprecierea rezultatelor inițiale de diagnostic şi tratament al ischemiei mezenteriale acute. Material şi Metodă: În perioada ianuarie 2009 mai 2011 au fost 29 cazuri consecutive de ischemie mezenterială acută. Vârsta medie a fost 70.3±2.4(35-95) ani, pacienții fiind internați la 37.1±8.1 (1-168) ore de la debutul bolii, scorul APACHE fiind de 24.79±1.9, scorul ASA - 3.32±0.1, scorul POSSUM - 37.45±1.9. Diagnoza a fost stabilit prin aprecierea: leucocitelor, lactatului seric, procalcitoninei, 3D-CT-angiogrfie si laparoscopie. Pacienții au fost tratați conform principiului ”second look” (n=21), anastomozei primare (n=2), laparatomii exploratorii (n=6). Ischemie mezenterială venoasă 5 cazuri și aretrială 24 cazuri Rezultate: Media leucocitelor la internare a fost de 17.88±1.7x109/L, media nesegmentatelor-29.0±4.2%, media lactatului seric 2.56±0.5mmol/L, la 8 pacienți testul PCT-Q a fost ≥10ng/ml, media glucozei sangvine la internare 11.3±1.2 mmol/L, la 21 de pacienți ea fiind mai mare de 6 mmol/L. Mortalitatea postoperatorie a fost 68.9% (n=20). Concluzie: Experiența inițială demonstrează că principiile anastomozei amânate, anastomozei primare pot fi considerate ca opțiuni chirurgicale pentru tratamentul pacienților cu ischemie mezenterială acută. Însă concluziile definitive privind momentul aplicării lor, vor fi formulate după analiza unui lot mai mare de pacienti.Introduction: Up to date there are no widely accepted evidence based principles for the diagnosis and treatment of acute mesenterial ischemia and the treatment outcomes are poor. The death rate in this group of patients varies between 70 and 90 %. Aim: to appreciate the initial diagnostic and treatment results of acute mesenterial ischemia. Material and methods: During January 2009 – May 2011 29 consecutive patients with mesenterial ischemia. The mean age was 70.3±2.4 (35-95) years, the mean time from onset to hospitalization was 37.1±8.1 (1-168) hours, the mean APACHE score was 24.79±1.9, ASA score – 3.32±0.1, POSSUM score was – 37.45±1.9. The diagnosis was established upon WBC, blood lactate level, procalcitonine, 3D-CT angiography and laparoscopy. The patients were treated using the “second look” principle (n=21), resection and primary anastomosis (n=2), diagnostic laparotomy (n=6). Venous and arterial mesenterial ischemia was diagnosed in 5 and 24 patients respectively. Results: The mean WBC upon admittance was 17.88±1.7x109/L, mean nonsegmented WBC was 29.0±4.2%, mean value of blood lactate level was 2.56±0.5mmol/L. In 8 patients the PCT-Q test was ≥10ng/ml, mean glucose level was 11.3±1.2 mmol/L and in 6 patients it was over 6 mmol/L. The postoperative death rate was 68.9% (n=20). Conclusions: The initial experience favors the “second look” principle and resection with primary anastomosis for the treatment of acute mesentery ischemia. Larger patients’ series are necessary in order to drag definitive conclusions regarding the optimal time for anastomosis

Primary tumors of jejunum and ileum: one center experience

Introduction: Primary benign and malignant tumors of jejunum and ileum are rare. They are very often diagnosed by accident or as a cause of acute abdomen. Purpose: The aim of study was to analyze the cases of primary tumors of jejunum and ileum admitted for surgical procedures in an emergency and elective setting. Materials and Methods: Retrospective review of all patients referred to our institution and diagnosed with primary tumors of jejunum and ileum and its complications during the last 7 years. Results: There were 15 pts (F-9, M-6) with mean age of 52.9 ±5.1 years (range from 17 to 79). Intussusceptions (n=6), intestinal obstruction (n=3), perforation (n=2), intussusceptions/ perforation with GI bleeding (n=2) were the most common clinical presentations. In 2 cases primary tumors of jejunum and ileum were detected as incidental findings during surgical procedure. Most tumors (n = ll, 73.3%) were located in the ileum. In 15 pts intestinal resection (R()-12, R ,-l) with end-to-end (n=7), side-to-side (n=6), Maydl procedure (n=l) and terminal ileostomy (n=l) were performed. There were 9 benign tumors (leiomyoma-4, angioleiomyoma- 2, fibrolipoma -2, fibroid polyp-1) and 6 malignant (c-KIT/CD 117 positive GISTs-2, lymphomas-2, neuroendocrine tumor-1, adenocarcinoma-1). Conclusion: Primary tumors of jejunum and ileum are rare, the symptoms often non-specific, and the accuracy of different diagnostic tests needs to be improved. Timing and type of the intervention to the process and biological behavior of the pathological cells predict the prognosis

Surgical treatment of acute mesenteric ischemia

Introduction: Acute mesenteric ischemia (AMI) is an abdominal catastrophe. Advanced age and diagnosis delay are associated with increased morbidity and mortality rates. The optimal surgical strategy for AMI is under evaluation. Aim: To evaluate the early results of different treatment strategies for AMI. Material and methods: During last three years a total of 35 consecutive pts with AMI were admitted to our unit. The mean (±SD) time interval between AMI symptoms onset and admission was 34.7±2.1 h. Physiological parameters (mean±SD) of pts were: ASA score - 3.3±0.1, APACHE score - 25.2±1.6 and POSSUM - 36.9±1.8. In most cases AMI was induced by superior mesenteric artery (SMA) embolism (54.3%, n = 19) followed by SMA thrombosis (25.7%, n= 9) and venous thrombosis (VT) (20%, n=7). Results: The affected bowel segments were: small intestine (n=16), small intestine + colon (n=13) and total ischemia (n=6). Surgical procedures were as follows: small intestine resection (n=14) with SMA embolectomy (n=2), small intestine + right colon (n=12) and small intestine + subtotal colectomy (n=l). In two cases of VT affected intestinal segments were not resected, instead anticoagulation treatment was initiated and the intestinal viability was confirmed by second-look laparotomy. Explorative laparotomy was used only in advanced intestinal gangrene (n=6). Twenty five pts with massive injury were scheduled for staged damage control approach (immediate resection of the involved bowel without gastrointestinal continuity reconstruction, patients’ resuscitation in ICU) combined with Negative Pressure Wound Therapy (V.A.C., KCI or homemade) and later on definitive reconstructive procedure (delayed anastomosis). Primary anastomoses were performed only in 2 pts with short segmental intestinal infarction. The overall 30-days mortality rate was 24/35, 68.5% (in non-total AMI - 18/29, 62%, in VT zero). Conclusions: Early diagnosis and prompt surgery improves the AMI outcome. Colon involved in AMI is a poor prognosis sign. Damage control approach improves the AMI patients’ survival

The evolution of bits and bottlenecks in a scientific workflow trying to keep up with technology: Accelerating 4D image segmentation applied to nasa data

In 2016, a team of earth scientists directly engaged a team of computer scientists to identify cyberinfrastructure (CI) approaches that would speed up an earth science workflow. This paper describes the evolution of that workflow as the two teams bridged CI and an image segmentation algorithm to do large scale earth science research. The Pacific Research Platform (PRP) and The Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI) resources were used to significantly decreased the earth science workflow's wall-clock time from 19.5 days to 53 minutes. The improvement in wall-clock time comes from the use of network appliances, improved image segmentation, deployment of a containerized workflow, and the increase in CI experience and training for the earth scientists. This paper presents a description of the evolving innovations used to improve the workflow, bottlenecks identified within each workflow version, and improvements made within each version of the workflow, over a three-year time period

Effect of Thermal Exposure on Structure of the Ultrafine-GrainedZr-1Nb Alloy

Effect of annealing at temperature range of 573–823 K on stability of the ultrafine-grained structure of the Zr-1wt.%Nb alloy was studied by methods of transmission electron microscopy. Growth kinetics of grain–subgrain structure elements of alloy was investigated

Self-expanding metal stent for refractory bleeding esophageal varices - single center experience

Introduction: Bleeding esophageal varices (EV) is a severe and life threatening complication of portal hypertension (PH), while endoscopic failure to control hemorrhage is even a more dramatic situation. Aim: To assess self-expanding metal stent (SEMS) haemostatic efficacy in severe variceal hemorrhage in patients with bleeding EV and endoscopic treatment failure. Material and Methods: A total of 12 patients, (M=8) with the mean ±SD age - 46.92±3.09 (24-62 years) and liver cirrhosis induced bleeding EV (n=8) and esophageal post-banding ulcers (n=4) were enrolled in the study. The main selection criteria was endoscopic treatment failure. A removable covered SEMS (SX-ELLA stent Danis, 135x25 mm, ELLA-CS, Hradec-Kralove, Czech Republic) was used in all cases. The mean SEMS used per patient was 1.25±0.18 (1-3). All definitions were used according to Baveno Consensus (I-V) conferences. Results: Initial SEMS haemostatic efficacy was 100%. Partial distal stent migration was documented on X-ray and CT-scan in 5/12(41.6%) and stent reposition was achieved by second-look endoscopy. The 30-days mortality was 25% (3/12). Tanatogenesis was induced by hepatic failure (n=2) and bleeding EV distally to the stent distal end (n=l). Conclusions: The preliminary results demonstrate that stenting is an effective life-saving hemostatic procedure in high-risk patients with severe esophageal variceal bleeding and endoscopic hemostasis failure as well as postbanding esophageal ulcers. Final conclusions will be reached after gaining experience with this new method on larger series