scholarly journals Atomistic Simulation of the Strain Driven Phase Transition in Pure Iron Thin Films Containing Twin Boundaries

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 953
Author(s):  
Yunqiang Jiang ◽  
Binjun Wang ◽  
Chun Xu ◽  
Jianguo Zhang
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Surface Orientation ◽  
Orientation Relationships ◽  
Twin Boundaries ◽  
Free Surfaces ◽  
Fraction Increase ◽  
Group 2 ◽  
Group 1 ◽  
Film Group

Using molecular dynamics (MD) simulation, the strain-induced phase transitions in pure body-centered-cubic (bcc) iron (Fe) thin films containing twin boundaries (TBs) with different TB fractions and orientations are studied. Two groups of bcc thin films with different TB-surface orientation relationships are designed. In film group 1, the (112) [ 11 1 ¯ ] TBs are perpendicular to the ( 11 1 ¯ ) free surfaces, while the (112) [ 11 1 ¯ ] TBs are parallel to the free surfaces in film group 2. We vary the TB numbers inserted into the films to study the effect of TB fraction on the phase transition. Biaxial strains are applied to the films to induce the bcc to close packed (cp) phase transition. The critical strain, at which the first phase transition takes place, decreases with the TB fraction increase in film group 1 with a perpendicular TB-surface orientation, while such a relationship is not observed in film group 2 with parallel TB-surface orientation. We focus on the free surface and TB as the nucleation positions of the new phase and the afterward growth. In addition, the dynamics of the phase transition is discussed. This work may help to understand the mechanism of phase transition in nanoscale or surface-dominant systems with pre-existing defects.

scholarly journals Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3631 ◽  
Author(s):  
Binjun Wang ◽  
Yunqiang Jiang ◽  
Chun Xu
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
Free Surface ◽  
Transition Temperature ◽  
Film Thickness ◽  
Martensitic Phase ◽  
Martensitic Transition ◽  
Twin Boundaries ◽  
Martensitic Phase Transition

Using molecular dynamics (MD) simulation, the austenitic and martensitic phase transitions in pure iron (Fe) thin films containing coherent twin boundaries (TBs) have been studied. Twelve thin films with various crystalline structures, thicknesses and TB fractions were investigated to study the roles of the free surface and TB in the phase transition. In the austenitic phase transition, the new phase nucleates mainly at the (112)bcc TB in the thicker films. The (111¯)bcc free surface only attends to the nucleation, when the film is extremely thin. The austenitic transition temperature shows weak dependence on the film thickness in thicker films, while an obvious transition temperature decrease is found in a thinner film. TB fraction has only slight influence on the austenitic temperature. In the martensitic phase transition, both the (1¯10)fcc free surface and (111)fcc TB attribute to the new body-center-cubic (bcc) phase nucleation. The martensitic transition temperature increases with decreased film thickness and TB fraction does not influent the transition temperature. In addition, the transition pathways were analyzed. The austenitic transition obeys the Burgers pathway while both the Kurdjumov–Sachs (K–S) and Nishiyama–Wassermann (N–W) relationship are observed in the martensitic phase transition. This work may help to understand the mechanism of phase transition in the Fe nanoscaled system containing a pre-existing defect.

scholarly journals Shear Deformation Helps Phase Transition in Pure Iron Thin Films with “Inactive” Surfaces: A Molecular Dynamics Study

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 855
Author(s):  
Ting Ruan ◽  
Binjun Wang ◽  
Chun Xu ◽  
Yunqiang Jiang
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
Free Surface ◽  
Phase Transitions ◽  
Shear Deformation ◽  
Dynamics Simulation ◽  
Nanoscale Systems ◽  
Free Surfaces ◽  
Nucleation Sites

In a previous study, it was shown that the (111)fcc, (110)fcc and (111)bcc free surfaces do not assist the phase transitions as nucleation sites upon heating/cooling in iron (Fe) thin slabs. In the present work, the three surfaces are denoted as “inactive” free surfaces. The phase transitions in Fe thin films with these “inactive” free surfaces have been studied using a classical molecular dynamics simulation and the Meyer–Entel potential. Our results show that shear deformation helps to activate the free surface as nucleation sites. The transition mechanisms are different in dependence on the surface orientation. In film with the (111)fcc free surface, two body-centered cubic (bcc) phases with different crystalline orientations nucleate at the free surface. In film with the (110)fcc surface, the nucleation sites are the intersections between the surfaces and stacking faults. In film with the (111)bcc surface, both heterogeneous nucleation at the free surface and homogeneous nucleation in the bulk material are observed. In addition, the transition pathways are analyzed. In all cases studied, the unstrained system is stable and no phase transition takes place. This work may be helpful to understand the mechanism of phase transition in nanoscale systems under external deformation.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin
Keyword(s):  
Vascular Graft ◽  
Graft Infection ◽  
Vascular Graft Infection ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Prosthetic Vascular Graft Infection ◽  
Group 1

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

The influence of continuous local wound infusion on postoperative pain in patients undergoing transfemoral amputation

VASA ◽  
2015 ◽  
Vol 44 (5) ◽  
pp. 381-386 ◽  
Author(s):  
Christian Uhl ◽  
Thomas Betz ◽  
Andrea Rupp ◽  
Markus Steinbauer ◽  
Ingolf Töpel
Keyword(s):  
Pain Management ◽  
Pilot Study ◽  
Local Anaesthetic ◽  
Phantom Pain ◽  
Transfemoral Amputation ◽  
Postoperative Wound ◽  
Stump Pain ◽  
Management Protocol ◽  
Group 2 ◽  
Group 1

Abstract. Summary: Background: This pilot study was set up to examine the effects of a continuous postoperative wound infusion system with a local anaesthetic on perioperative pain and the consumption of analgesics. Patients and methods: We included 42 patients in this prospective observational pilot study. Patients were divided into two groups. One group was treated in accordance with the WHO standard pain management protocol and in addition to that received a continuous local wound infusion treatment (Group 1). Group 2 was treated with analgesics in accordance with the WHO standard pain management protocol, exclusively. Results: The study demonstrated a significantly reduced postoperative VAS score for stump pain in Group 1 for the first 5 days. Furthermore, the intake of opiates was significantly reduced in Group 1 (day 1, Group 1: 42.1 vs. Group 2: 73.5, p = 0.010; day 2, Group 1: 27.7 vs. Group 2: 52.5, p = 0.012; day 3, Group 1: 23.9 vs. Group 2: 53.5, p = 0.002; day 4, Group 1: 15.7 vs. Group 2: 48.3, p = 0.003; day 5, Group 1 13.3 vs. Group 2: 49.9, p = 0.001). There were no significant differences between the two groups, neither in phantom pain intensity at discharge nor postoperative complications and death. Conclusions: Continuous postoperative wound infusion with a local anaesthetic in combination with a standard pain management protocol can reduce both stump pain and opiate intake in patients who have undergone transfemoral amputation. Phantom pain was not significantly affected.

Abnormal Haemostasis and Blood Viscosity in Malignant Hypertension

1984 ◽  
Vol 52 (03) ◽  
pp. 253-255 ◽  
Author(s):  
C Isles ◽  
G D O Lowe ◽  
B M Rankin ◽  
C D Forbes ◽  
N Lucie ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Viscosity ◽  
Renal Damage ◽  
Antithrombin Iii ◽  
Plasma Viscosity ◽  
Malignant Hypertension ◽  
Fibrin Deposition ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

SummaryWe have previously shown abnormalities of haemostasis suggestive of intravascular coagulation in patients with malignant hypertension, a condition associated with retinopathy and renal fibrin deposition. To determine whether such abnormalities are specific to malignant hypertension, we have measured several haemostatic and haemorheological variables in 18 patients with malignant hypertension (Group 1), 18 matched healthy controls (Group 2), and 18 patients with non-malignant hypertension (Group 3) matched for renal pathology, blood pressure and serum creatinine with Group 1. Both Groups 1 and 3 had increased mean levels of fibrinogen, factor VIIIc, beta-thrombo- globulin, plasma viscosity and blood viscosity (corrected for haematocrit); and decreased mean levels of haematocrit, antithrombin III and platelet count. Mean levels of fast antiplasmin and alpha2-macroglobulin were elevated in Group 1 but not in Group 3. We conclude that most blood abnormalities are not specific to malignant hypertension; are also present in patients with non-malignant hypertension who have similar levels of blood pressure and renal damage; and might result from renal damage as well as promoting further renal damage by enhancing fibrin deposition. However increased levels of fibrinolytic inhibitors in malignant hypertension merit further investigation in relation to removal of renal fibrin.

Total Knee Arthroplasty after Previous Ipsilateral Hip Arthroplasty Showed Lower Clinical Outcomes and Higher Leg Length Discrepancy Perception

2020 ◽  
Author(s):  
Han-Jun Lee ◽  
Seong Hwan Kim ◽  
Nicolas Pujol ◽  
Yong-Beom Park
Keyword(s):  
Clinical Outcomes ◽  
Hip Arthroplasty ◽  
Leg Length ◽  
Function Score ◽  
Patient’S Satisfaction ◽  
Length Discrepancy ◽  
Total Knee ◽  
Group 2 ◽  
Ks Function ◽  
Group 1

AbstractThe purpose of this study is to compare perception of leg length discrepancy (LLD) and clinical results of total knee arthroplasties (TKA) in patients with or without previous ipsilateral hip arthroplasty. Between 2008 and 2015, navigation-assisted TKA was performed in 43 patients with previous hip arthroplasty after hip fracture. After 1:3 propensity score matching was performed, 108 patients of primary navigation-assisted TKA (group 1) and 36 patients with hip arthroplasty (group 2) were included. Knee Society (KS) scores, Western Ontario and McMaster Universities Index (WOMAC) scores, and patients' satisfaction including perception of LLD were evaluated. Radiographic evaluation included mechanical axis, component position, and LLD. Logistic regression analysis was performed to find the factors that affect the clinical outcomes. No significant differences in radiologic and clinical evaluations, except for KS function score, patient's satisfaction and LLD (p< 0.001), were detected between the groups. LLD and its perception were significantly higher in group 2 (1.8 ± 3.4 mm in group 1 and 9.7 ± 4.1 mm in group 2, p = 0.000). Risk factors for the low KS function score were found as LLD (odds ratio [OR]: 1.403, p = 0.008) and previous hip arthroplasty itself (OR: 15.755, p = 0.002), but much higher OR was found in previous hip arthroplasty. Although the outcomes of TKA in patients with ipsilateral hip arthroplasty are comparable to those of primary TKA, LLD was high and patient's satisfaction and functional outcomes were low in patients with previous ipsilateral hip arthroplasty. Care should be taken when considering TKA in patients with previous hip arthroplasty. This is a Level III, case control study.

Clinical and Radiological Changes after use of Alpha-1 Blocker Therapy in Patients of Posterior Urethral Valve with Bladder Neck Hypertrophy

JMS SKIMS ◽  
2009 ◽  
Vol 12 (1) ◽  
pp. 3-7
Author(s):  
Aejaz A Baba ◽  
Bajpai Minu
Keyword(s):  
Bladder Neck ◽  
Posterior Urethral Valve ◽  
Posterior Urethral Valves ◽  
Blocker Therapy ◽  
Urethral Valve ◽  
Novel Method ◽  
Radiological Changes ◽  
Group 2 ◽  
Mean Time ◽  
Group 1

Background: We evaluated the effects of alpha-1 blocker therapy on clinical and radiological abnormalities in patients of posterior urethral valve with bladder neck hypertrophy. Materials and Methods: A total of 74 patients with posterior urethral valves were seen at our department between 2003 and 2007. Out of these 24 had radiological evidence of bladder neck hypertrophy. Those patients with bladder neck hypertrophy who were seen before June 2006 and did not receive alpha-1 blocker (prazocin) therapy after valve ablation were assigned to group 1 (n=10). Group 2 consisted of 14 age matched patients with bladder neck hypertrophy and comparable prognostic factors who received alpha-1 blocker therapy after valve ablation (n=14). Micturating cystourethrography (MCU) was done periodically and a novel method used to calculate bladder neck hypertrophy. Trends in symptoms and radiological changes were evaluated throughout follow-up. Results: Mean patient age at presentation was 3.02±2.68 years in group 1 and 3.12±3.4 years in group 2. Bladder neck hypertrophy decreased from 2.3±1.0 to 2.0±0.5 in a mean time of 52.0 (34-52) weeks in group 1 where as it decreased from 2.2±0.5 to 1.6±0.3 in a mean time of 32.0 (22-52) weeks. Symptomatically patients in group 2 who received alpha-1 blocker therapy after valve ablation were better and had quick resolution of bladder neck hypertrophy. Conclusions: Use of alpha-1 blocker therapy in patients of posterior urethral valve with bladder neck hypertrophy helps in quick resolution of bladder neck hypertrophy. J Med Sci 2009;12(1):3-7.

Preoperative Platelet to Lymphocyte Ratio Is Associated with Early Morbidity and Mortality after Coronary Artery Bypass Grafting

2015 ◽  
Vol 18 (6) ◽  
pp. 255 ◽  
Author(s):  
Hüseyin Şaşkın ◽  
Çagrı Düzyol ◽  
Kazım Serhan Özcan ◽  
Rezan Aksoy ◽  
Mustafa Idiz
Keyword(s):  
Coronary Artery ◽  
Coronary Artery Bypass Grafting ◽  
Coronary Artery Bypass ◽  
Artery Bypass ◽  
Bypass Grafting ◽  
Platelet To Lymphocyte Ratio ◽  
Artery Bypass Grafting ◽  
Lymphocyte Ratio ◽  
Group 2 ◽  
Group 1

<strong>Objective:</strong> To investigate the association of platelet to lymphocyte ratio to mortality and morbidity after coronary artery bypass grafting operation.<br /><strong>Methods:</strong> We evaluated records of 916 patients who underwent coronary artery bypass grafting operation between January 2009 and May 2014 retrospectively. Patients were grouped as Group 1 (n = 604) if the platelet to lymphocyte ratio was above 142 and Group 2 (n = 312) if platelet to lymphocyte ratio was below 142.<br /><strong>Results:</strong> The number of patients who developed a neurologic event during the hospital stay and in the first postoperative month was 7 (1.2%) in Group 1 and 12 (3.8%) in Group 2 for which the difference was statistically significant (P = .007). Early term mortality occurred in 3 patients (0.5%) in Group 1 and in 10 patients (3.2%) in Group 2 for which the difference was statistically highly significant (P = .001). In univariate and multivariate regression analysis, the preoperative platelet to lymphocyte ratio was determined as an independent risk factor for occurrence of atrial fibrillation in the early postoperative period, reoperation for sternum dehiscence, occurrence of a neurologic event, prolonged stay in the hospital and mortality.<br /><strong>Conclusion:</strong> In this study, elevated levels of platelet to lymphocyte ratio were associated with mortality and morbidity after coronary artery bypass grafting operation.

Immediate and long-term results of the first line chemotherapy in patients with metastatic triple negative breast cancer. Final analysis of randomized study

2020 ◽  
pp. 75-80
Author(s):  
S.A. Lyalkin ◽  
◽  
L.A. Syvak ◽  
N.O. Verevkina ◽  
◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Randomized Study ◽  
Progression Free Survival ◽  
First Line ◽  
Free Survival ◽  
Group 2 ◽  
Line Chemotherapy ◽  
Group 1

The objective: was to evaluate the efficacy of the first line chemotherapy in patients with metastatic triple negative breast cancer (TNBC). Materials and methods. Open randomized study was performed including 122 patients with metastatic TNBC. The efficacy and safety of the first line chemotherapy of regimens АТ (n=59) – group 1, patients received doxorubicine 60 мг/м2 and paclitaxel 175 мг/м2 and ТР (n=63) – group 2, patients received paclitaxel 175 мг/м2 and carboplatin AUC 5 were evaluated. Results. The median duration of response was 9.5 months (4.5–13.25 months) in patients received AT regimen and 8.5 months (4.7–12.25 months), in TP regimen; no statistically significant differences were observed, р=0.836. The median progression free survival was 7 months (95% CI 5–26 months) in group 1 and 7.5 months (95% CI 6–35 months) in group 2, p=0.85. Both chemotherapy regimens (AT and TP) had mild or moderate toxicity profiles (grade 1 or 2 in most patients). No significant difference in gastrointestinal toxicity was observed. The incidence of grade 3–4 neutropenia was higher in patients of group 2 (TP regimen): 42.8% versus 27% (р<0.05). Conclusions. Both regimens of chemotherapy (AT and TP) are appropriate to use in the first line setting in patients with metastatic TNBC. Key words: metastatic triple negative breast cancer, chemotherapy, progression free survival, chemotherapy toxicity.

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