Superplastic deformation of two phase MgLiAl alloy after TCAP pressing

Magnesium based alloy containing 9 wt. % Li, 1,5 wt. % Al, composed of alpha + beta (hcp + bcc) phases was cast under argon atmosphere and extruded at 350 degrees C as bars of cross section 12x12 mm. Twist Channel Angular Pressing TCAP deformation was applied at a temperature of 160 degrees C using BC rotation of samples in the following passes. TCAP tool consisted of helical part in horizontal area of the channel with an angle of lead gamma = 30 degrees to simulate back pressure and thus to increase the extrusion force. The initial grain size of the hexagonal. phase estimated at 30 mu m decreased in the following passes down to 6 mu m and that of bcc. phase decreased after TCAP from initial 12 mu m, down to 5 mu m. TEM studies after TCAP passes showed higher dislocation density in the. region than in the alpha phase. Crystallographic relationship (001) alpha || (110) beta indicates parallel positioning of slip planes of both phases due to activation of slip. Electron diffraction indicates increase of grain misorientation with a number of TCAP passes. Stress/strain curves measured at temperature of 200 degrees C show superplastic forming after 1st and 3rd TCAP passes with better superplastic properties with increasing number of passes. Values of strain rate sensitivity coefficient m were calculated at 0.31 after 1 TCAP pass using flow stress values from step strain increase curves. The sample after 3 TCAP passes showed increase of m value up to 0.47 for the strain rate range 10(-5)-5 x 10(-4) s(-1). Obtained values are slightly lower than those reported in the literature, however increase of a number of TCAP passes has a positive effect on superplastic properties due to fine grains and increase of their misorientation.Web of Science23322121

UrBIOfuture webinar

Based on results of 'UrBIOfuture experience survey' and co-creation workshop, the webinar is dedicated to University students (undergraduate, master and PhD students). According to 'main results of the UrBIOfuture experience survey' the event is dedicated to low and middle skilled audiences, and gives a practical information session with little theor

UrBIOfuture webinar

Based on results of 'UrBIOfuture experience survey' and co-creation workshop, the webinar is dedicated to University students (undergraduate, master and PhD students). According to 'main results of the UrBIOfuture experience survey' the event is dedicated to low and middle skilled audiences, and gives a practical information session with little theor

Effect of various SPD techniques on structure and superplastic deformation of two phase MgLiAl alloy

MgLiAl alloy containing 9 wt% Li and 1.5% Al composed of hexagonal alpha and bcc beta phases was cast under protecting atmosphere and hot extruded. Various methods of severe plastic deformation were applied to study their effect on structure and grain refinement. Rods were subjected to 1-3 passes of Twist Channel Angular Pressing TCAP (with helical component), cyclic compression to total strain epsilon = 5 using MAXStrain Gleeble equipment, both performed at temperature interval 160-200 A degrees C and, as third SPD method, KOBO type extrusion at RT. The TCAP pass resulted in grain refinement of alpha phase from 30 mu m down to about 2 mu m and that of beta phase from 12 to 5 mu m. Maxstrain cycling 10 x up to epsilon = 5 led to much finer grain size of 300 nm. KOBO method performed at RT caused average grain size refinement of alpha and beta phases down to about 1 mu m. Hardness of alloy decreased slightly with increasing number of TCAP passes due to increase of small void density. It was higher after MAXStrain cycling and after KOBO extrusion. TEM studies after TCAP passes showed higher dislocation density in the beta region than in the alpha phase. Crystallographic relationship (001) alpha|| (110) beta indicated parallel positioning of slip planes of both phases. Electron diffraction technique confirmed increase of grain misorientation with number of TCAP passes. Stress/strain curves recorded at temperature 200 A degrees C showed superplastic forming after 1st and 3rd TCAP passes with better superplastic properties due to higher elongation with increasing number of passes. Values of strain rate sensitivity coefficient m were calculated at 0.29 after 3rd TCAP pass for strain rate range 10(-5) to 5 x 10(-3) s(-1). Deformation by MAXStrain cycling caused much more effective grain refinement with fine microtwins in alpha phase. Superplastic deformation was also observed in alloy deformed by KOBO method, however the value of m = 0.21 was obtained at lower temperature of deformation equal to 160 A degrees C and deformation rate in the range 10(-5) to 5 x 10(-3). Tensile samples deformed superplastically showed grain growth and void formation caused by grain boundary slip. Summarizing, all methods applied resulted in sufficient grain refinement to obtain the effect of superplastic deformation for alloys of two phase alpha + beta structure.Web of Science2451089107

Maternal Plasma Metabolomic Profiles in Spontaneous Preterm Birth: Preliminary Results

Objective. To profile maternal plasma metabolome in spontaneous preterm birth. Method. In this retrospective case-control study, we have examined plasma of patient with preterm birth (between 22 and 36 weeks of pregnancy (n=57)), with threatened preterm labor (between 23 and 36 weeks of pregnancy (n=49)), and with term delivery (n=25). Plasma samples were analysed using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) in positive and negative polarity modes. Results. We found 168 differentially expressed metabolites that were significantly distinct between study groups. We determined 51 metabolites using publicly available databases that could be subdivided into one of the five groups: amino acids, fatty acids, lipids, hormones, and bile acids. PLS-DA models, verified by SVM classification accuracy, differentiated preterm birth and term delivery groups. Conclusions. Maternal plasma metabolites are different between term and preterm parturitions. Part of them may be related with preterm labor, while others may be affected by gestational age or the beginning of labor. Metabolite profile can classify preterm or term delivery groups raising the potential of metabolome as a biomarker to identify high-risk pregnancies. Metabolomic studies are also a tool to detect individual compounds that may be further tested in targeted researches

Chemokines Profiling of Patients with Preterm Birth

Introduction. Nowadays it is thought that the main cause of premature birth is subclinical infection. However, none of the currently used methods provide effective prevention to preterm labor. The aim of the study was to determine the concentration of selected chemokines in sera of patients with premature birth without clinical signs of infection (n=62), threatened preterm labor (n=47), and term births (n=28). Method. To assess the concentration of chemokines in the blood serum, we used a multiplex method, which allows the simultaneous determination of 40 chemokines per sample. The sets consist of the following chemokines: 6Ckine/CCL21, Axl, BTC, CCL28, CTACK/CCL27, CXCL16, ENA-78/CXCL5, Eotaxin-3/CCL26, GCP-2/CXC, GRO (GROα/CXCL1, GROβ/CXCL2 and GROγ/CXCL3), HCC-1/CCL14, HCC-4/CCL16, IL-9, IL-17F, IL18-BPa, IL-28A, IL-29, IL-31, IP-10/CXCL10, I-TAC/CXCL11, LIF, LIGHT/TNFSF14, Lymphotactin/XCL1, MCP-2/CCL8, MCP-3/CCL7, MCP-4/CCL13, MDC/CCL22, MIF, MIP-3α/CCL20, MIP-3-β/CCL19, MPIF-1/CCL23, NAP-2/CXCL7, MSPα, OPN, PARC/CCL18, PF4, SDF-1/CXCL12, TARC/CCL17, TECK/CCL25, and TSLP. Results. We showed possible implication of 4 chemokines, that is, HCC-4, I-TAC, MIP-3α, and TARC in women with symptoms of preterm delivery. Conclusion. On the basis of our findings, it seems that the chemokines may play role in the pathogenesis of preterm labor. Defining their potential as biochemical markers of preterm birth requires further investigation on larger group of patients

Increased Maternal and Cord Blood Betatrophin in Gestational Diabetes.

The aim of the study was to compare maternal and cord blood levels of betatrophin--a new peptide potentially controlling beta cell growth--as well as in its mRNA expression in subcutaneous adipose tissue, visceral adipose tissue and placental tissue obtained from pregnant women with normal glucose tolerance (NGT) and gestational diabetes (GDM).Serum betatrophin and irisin concentrations were measured by ELISA in 93 patients with GDM and 97 women with NGT between 24 and 28 week of gestation. Additionally, maternal and cord blood betatrophin and irisin, as well as their genes (C19orf80 and Fndc5) expression were evaluated in 20 patients with GDM and 20 women with NGT at term.In both groups, serum betatrophin concentrations were significantly higher in the patients with GDM than in the controls (1.91 [1.40-2.60] ng/ml vs 1.63 [1.21-2.22] ng/ml, p=0.03 and 3.45 [2.77-6.53] ng/ml vs 2.78 [2.16-3.65] ng/ml, p=0.03, respectively). Cord blood betatrophin levels were also higher in the GDM than in the NGT group (20.43 [12.97-28.80] ng/ml vs 15.06 [10.11-21.36] ng/ml, p=0.03). In both groups betatrophin concentrations in arterial cord blood were significantly higher than in maternal serum (p=0.0001). Serum irisin levels were significantly lower in the patients with GDM (1679 [1308-2171] ng/ml) than in the healthy women between 24 and 28 week of pregnancy (1880 [1519-2312] ng/ml, p=0.03). Both C19orf80 and Fndc5 mRNA expression in fat and placental tissue did not differ significantly between the groups studied.Our results suggest that an increase in maternal and cord blood betatrophin might be a compensatory mechanism for enhanced insulin demand in GDM