40Ar/39Ar and K–Ar age constraints on shear zone evolution, southern Taltson magmatic zone, northeastern Alberta

1995 ◽  
Vol 32 (3) ◽  
pp. 281-291 ◽  
Author(s):  
H. E. Plint ◽  
M. R. McDonough
Keyword(s):  
Cooling Rate ◽  
Shear Zone ◽  
High Grade ◽  
Slow Cooling ◽  
Rapid Cooling ◽  
Deformational History ◽  
The Mean ◽  
Exhumation Rates ◽  
Northeastern Alberta ◽  
Age Constraints

New 40Ar/39Ar analyses of hornblende, muscovite, biotite, and K-feldspar constrain the timing of deformation and cooling of the southern Taltson magmatic zone, which underwent lower granulite to upper amphibolite grade deformation, in part synchronous with voluminous 1.99–1.92 Ga magmatism. New data are combined with existing K–Ar dates into a regional cooling framework to provide thermotemporal constraints on the deformational history. 40Ar/39Ar hornblende ages of ca. 1900 Ma are interpreted to record relatively rapid cooling following ductile thrusting on the Andrew Lake shear zone, and younger anatectic magmatism. These data, with published K–Ar and U–Pb data, support relatively rapid cooling of the Taltson magmatic zone from monazite closure temperature of 725 °C at ca. 1930 Ma to 525 °C at ca. 1900 Ma. Cooling rate estimates are about 7 °C/Ma, which suggests moderate exhumation rates during the high-grade part of the deformational history. A muscovite 40Ar/39Ar plateau age of 1803 ± 11 Ma is consistent with the mean muscovite K–Ar age of 1792 Ma, indicating regional cooling through about 350 °C at ca. 1800 Ma. 40Ar/39Ar ages from magmatic biotite of 1856 and 1799 Ma also suggest slow cooling during greenschist grade deformation, which can be no older than ca. 1860 Ma. A K-feldspar 40Ar/39Ar age of 1681 Ma provides a lower limit for the time of greenschist grade deformation. Cooling rate estimates during amphibolite to greenschist grade deformation are 1.75–2.25 °C/Ma.

U – Pb age constraints for the lithotectonic evolution of the Grenville Province along the Mauricie transect, Quebec

1997 ◽  
Vol 34 (3) ◽  
pp. 299-316 ◽  
Author(s):  
David Corrigan ◽  
Otto van Breemen
Keyword(s):  
Shear Zone ◽  
Tectonic Evolution ◽  
High Grade ◽  
Isotopic Age ◽  
Grenville Province ◽  
Zircon Age ◽  
South Central ◽  
Continental Arc ◽  
Structural Levels ◽  
Age Constraints

New U–Pb zircon and monazite ages on 12 samples from the Mauricie transect in Quebec provide constraints on the lithologic and tectonic evolution of the south-central Grenville Province. From lowest to highest structural levels, the Mékinac, Shawinigan, and Portneuf – St. Maurice domains are identified on the basis of protolith age, tectonic overprint, and plutonism. The structurally highest Portneuf – St. Maurice domain consists of remnants of an island arc (Montauban Group) that was deformed and metamorphosed before and during the intrusion of continental arc plutons (La Bostonnais complex). A tonalitic orthogneiss yielding a [Formula: see text] zircon age suggests that most of the structurally underlying Mékinac and Shawinigan domains consist of orthogneisses that may be high-grade equivalents of the La Bostonnais complex. A voluminous metasedimentary unit occurring in the Shawinigan domain (St. Boniface unit) was deposited between ca. 1.18 and 1.09 Ga, precluding any correlation with the ca. 1.45 Ga Montauban Group. Two suites of anorthosite–mangerite–charnockite–granite (AMCG) plutonic rocks are identified on the basis of field relationships and isotopic age. A megacrystic granite belonging to the "older" AMCG suite yielded a [Formula: see text] zircon age. Three plutons from the "younger" suite yielded ages of [Formula: see text], 1059 ± 2, and 1056 ± 2 Ma. The Mékinac and Shawinigan domains, excluding the younger AMCG plutons, were penetratively deformed at granulite to uppermost amphibolite facies during west-northwest-directed thrusting between 1.15 and 1.09 Ga. At ca. 1.09 Ga, a transition from contraction to oblique extension resulted in the juxtaposition of the "cold" Portneuf – St. Maurice domain with the "hot" Shawinigan domain, along the Tawachiche shear zone. Oblique extension may have been active from ca. 1.09 to 1.04 Ga and was contemporaneous with emplacement of the younger AMCG suite.

EFFECTS OF COOLING RATE AND POURING TEMPERATURE ON MICROSTRUCTURE AND FRACTURE TOUGHNESS OF THE INDUCTION MELTED Nb-16Si-22Ti-2Hf-2Cr-2Al ALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2946-2951
Author(s):  
LINA JIA ◽  
JINGRU GE ◽  
JIANGBO SHA ◽  
HU ZHANG
Keyword(s):  
Fracture Toughness ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Columnar Structure ◽  
Al Alloy ◽  
Induction Melting ◽  
Pouring Temperature ◽  
Slow Cooling ◽  
Volume Fractions ◽  
The Mean

The effects of cooling rate and pouring temperature on microstructure and fracture toughness of the induction melted Nb -16 Si -22 Ti -2 Hf -2 Cr -2 Al alloy were extensively investigated. The results revealed that with the decrease of cooling rates, the Nbss exhibits the dendrite-like morphology, the primary Nb 5 Si 3 blocks form and the mean sizes of Nb 5 Si 3, Nbss and eutectic colonies increase; with the increase of the pouring temperature, the microstructure shows columnar structure and the particles of Nb 5 Si 3 or Nbss become long and thin. Pouring temperature and cooling rate had little influence on the volume fractions of Nbss and Nb 5 Si 3 and their compositions. The Nb 3 Si phase eliminated in the case of high pouring temperature and slow cooling rate. Fracture toughness of the alloy prepared by induction melting is on the order of 13.7 to 15.3 MPa·m1/2. Similar fracture toughness value of each slab may be ascribes to the same volume fraction of the Nbss .

Non-isothermal crystallization behavior of spinel crystals in FeO-SiO2-TiO2-V2O3-Cr2O3 slag

2018 ◽  
Vol 116 (1) ◽  
pp. 110
Author(s):  
Lixiong Shao ◽  
Jiang Diao ◽  
Wang Zhou ◽  
Tao Zhang ◽  
Bing Xie
Keyword(s):  
Cooling Rate ◽  
Crystallization Behavior ◽  
Crystal Size ◽  
Growth Mechanisms ◽  
Vanadium Slag ◽  
Growth Behaviour ◽  
Temperature Range ◽  
Chromium Spinel ◽  
Mean Diameter ◽  
The Mean

The growth behaviour of spinel crystals in vanadium slag with high Cr2O3 content was investigated and clarified by statistical analyses based on the Crystal Size Distribution (CSD) theory. The results indicate that low cooling rate and Cr2O3 content benefit the growth of spinel crystals. The chromium spinel crystals firstly precipitated and then acted as the heterogeneous nuclei of vanadium and titanium spinel crystals. The growth mechanisms of the spinel crystals at the cooling rate of 5 K/min consist two regimes: firstly, nucleation control in the temperature range of 1873 to 1773 K, in which the shapes of CSD curves are asymptotic; secondly, surface and supply control within the temperature range of 1773 to 1473 K, in which the shapes of CSD curves are lognormal. The mean diameter of spinel crystals increases from 3.97 to 52.21 µm with the decrease of temperature from 1873 to 1473 K.

The Prognostic Significance of DNA Topoisomerase II-alpha (Ki-S1), p21/Cip-1, and p27/Kip-1 Protein Immunoexpression in Oligodendrogliomas

2001 ◽  
Vol 125 (7) ◽  
pp. 892-898 ◽  
Author(s):  
Andrey Korshunov ◽  
Andrey Golanov
Keyword(s):  
Topoisomerase Ii ◽  
World Health ◽  
Low Grade ◽  
Image Analyzer ◽  
High Grade ◽  
Dna Topoisomerase Ii ◽  
Survival Times ◽  
Topoisomerase Ii Alpha ◽  
Dna Topoisomerase ◽  
The Mean

Abstract Objective.—To evaluate a possible association between clinical outcome of patients with oligodendroglioma and expression of 2 cyclin-dependent kinase inhibitors, p21/Cip-1 (p21) and p27/Kip-1 (p27), and of DNA topoisomerase II-alpha (Ki-S1), which has been recently used as a marker of cellular proliferation. Design.—Ninety-one specially selected patients with cerebral oligodendrogliomas treated with surgery and radiotherapy were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to p21, p27, and Ki-S1. A computerized color image analyzer was used to count immunostained nuclei. Results.—The mean Ki-S1 labeling index (LI) was found to be significantly prominent for World Health Organization (WHO) high-grade tumors (9.5% vs 3.2% for WHO low-grade tumors). In contrast, the mean p27 LI was significantly higher for low-grade tumors (43.3% vs 25.7% for high-grade tumors). The number of p21-positive cases and the mean p21 LI were found to be relatively equal for low- and high-grade tumors. For low-grade oligodendrogliomas, the progression-free and overall survival times were found to be significantly shorter for tumors with p27 LIs less than 20%. For high-grade oligodendrogliomas, survival times were significantly reduced for tumors with Ki-S1 LIs greater than 10%. Regression-tree analysis identified 4 groups of oligodendrogliomas with distinctly different outcomes: (1) 32 patients with low-grade tumors and p27 LIs greater than 20%; (2) 14 patients with low-grade tumors and p27 LIs less than 20%; (3) 25 patients with high-grade tumors and Ki-S1 LIs less than 10%; and (4) 20 patients with high-grade tumors and Ki-S1 LIs greater than 10%. Conclusions.—Immunoreactivity for Ki-S1 and p27 was found to be useful for further subdividing oligodendroglioma prognoses among low-grade and high-grade tumors. It seems unlikely that p21 immunohistochemistry will be of value for determining clinical outcomes for patients with oligodendrogliomas.

scholarly journals Correlation of Processing, Inner Structure, and Part Properties of Injection Moulded Thin-Wall Parts on Example of Polyamide 66

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Dietmar Drummer ◽  
Steve Meister
Keyword(s):  
Cooling Rate ◽  
Injection Moulding ◽  
Degree Of Crystallinity ◽  
Process Conditions ◽  
Thin Wall ◽  
Polyamide 66 ◽  
Slow Cooling ◽  
Cooling Conditions ◽  
Internal Structures ◽  
Wall Injection

In micro- and thin-wall injection moulding the process conditions affect the developed internal structures and thus the resulting part properties. This paper investigates exemplarily on polyamide 66 the interactions of different cooling conditions on the morphological and crystalline structures. The investigations reveal that a slow cooling rate of the melt results in a homogeneous morphology and a higher degree of crystallinity and also a favoured crystalline structure. Consequently, the dielectric behaviour and light transmitting part properties are affected.

Diagnostic value of apparent diffusion coefficient in differentiating between high-grade gliomas and brain metastases

2017 ◽  
Vol 59 (5) ◽  
pp. 599-605 ◽  
Author(s):  
Ionut Caravan ◽  
Cristiana Augusta Ciortea ◽  
Alexandra Contis ◽  
Andrei Lebovici
Keyword(s):  
Diffusion Coefficient ◽  
Brain Metastases ◽  
Apparent Diffusion Coefficient ◽  
Curve Analysis ◽  
High Grade ◽  
Peritumoral Edema ◽  
Roc Curve Analysis ◽  
Apparent Diffusion ◽  
Adc Values ◽  
The Mean

Background High-grade gliomas (HGGs) and brain metastases (BMs) can display similar imaging characteristics on conventional MRI. In HGGs, the peritumoral edema may be infiltrated by the malignant cells, which was not observed in BMs. Purpose To determine whether the apparent diffusion coefficient values could differentiate HGGs from BMs. Material and Methods Fifty-seven patients underwent conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) before treatment. The minimum and mean ADC in the enhancing tumor (ADCmin, ADCmean) and the minimum ADC in the peritumoral region (ADCedema) were measured from ADC maps. To determine whether there was a statistical difference between groups, ADC values were compared. A receiver operating characteristic (ROC) curve analysis was used to determine the cutoff ADC value for distinguishing between HGGs and BMs. Results The mean ADCmin values in the intratumoral regions of HGGs were significantly higher than those in BMs. No differences were observed between groups regarding ADCmean values. The mean ADCmin values in the peritumoral edema of HGGs were significantly lower than those in BMs. According to ROC curve analysis, a cutoff value of 1.332 × 10−3 mm2/s for the ADCedema generated the best combination of sensitivity (95%) and specificity (84%) for distinguishing between HGGs and BMs. The same value showed a sensitivity of 95.6% and a specificity of 100% for distinguishing between GBMs and BMs. Conclusion ADC values from DWI were found to distinguish between HGGs and solitary BMs. The peritumoral ADC values are better than the intratumoral ADC values in predicting the tumor type.

On thrusting, regional unconformities and exhumation of high-grade greenstones in Neoarchean orogens. The case of the Waroonga Shear Zone, Yilgarn Craton

2017 ◽  
Vol 712-713 ◽  
pp. 362-395 ◽  
Author(s):  
I. Zibra ◽  
F.J. Korhonen ◽  
M. Peternell ◽  
R.F. Weinberg ◽  
S.S. Romano ◽  
...  
Keyword(s):  
Shear Zone ◽  
High Grade ◽  
Yilgarn Craton

Viability of ovarian tissue after freezing

1957 ◽  
Vol 147 (929) ◽  
pp. 520-528 ◽  
Keyword(s):  
Systematic Study ◽  
Normal Saline ◽  
Ovarian Tissue ◽  
Cumulus Cells ◽  
Rapid Freezing ◽  
Freezing And Thawing ◽  
Slow Cooling ◽  
Rapid Cooling ◽  
Fertilized Egg ◽  
Cells Cultured

The fertilized egg of the rabbit, obtained from the Fallopian tube, is very sensitive to freezing and thawing, even after treatment with glycerol (Smith 1953). By contrast, the cumulus cells of the follicular granulosa which adhere to the egg after ovulation are much more resistant, and a few survive without any special precautions being taken (Smith 1949). A systematic study of the viability of the cumulus cells cultured after freezing and thawing by various methods (Smith 1953) gave the following results: (1) A majority of the cells survived when suspended in homologous serum, cooled slowly to — 79° C and thawed rapidly at + 40° C. Very few survived rapid freezing. (2) Addition of 15 % glycerol to the suspending medium improved survival after slow cooling but not after rapid cooling. (3) Cells suspended in normal saline failed to survive either slow or rapid cooling. Addition of glycerol promoted some survival after slow cooling. These experiments emphasized the need for slow cooling, already demonstrated with bull spermatozoa, and the superiority of serum over saline as a suspending medium. The addition of glycerol to the medium, though conducive to survival after freezing and thawing, was not as necessary as with spermatozoa.

scholarly journals The Pattern of Day Case (Ambulatory) Percutaneous (PCNL): A Descriptive Retrospective Study from a Tertiary Care Hospital

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Rehan Fareed ◽  
Huma Shamim
Keyword(s):  
Retrospective Study ◽  
Tertiary Care ◽  
Ureteral Stones ◽  
Transfusion Rate ◽  
Care Hospital ◽  
High Grade ◽  
High Grade Fever ◽  
Access Methods ◽  
The Mean ◽  
Staghorn Stones

Background: Percutaneous nephrolithotomy (PCNL) has experienced remarkable development and alteration since it was first described in 1976 by Fernstorm et al. It has also experienced miniaturization of equipment, improvement in operative systems, and refining renal access methods leading to the achievement of maximum clearance of stone while causing minimal morbidity. For example, in endourological practice, when the patient is subjected to PCNL, he traditionally needs programmed inpatient admission, as part of their recovery, it is applicable as an outpatient method in properly selected cases. Objectives: We aimed at evaluating the safety and applicability of the outpatient PCNL procedure. Methods: This retrospective study was done on 210 cases of tubeless PCNL performed by a single urologist at our institute from January 2016 to January 2019. Patients’ mean age (134 males and 76 females) was 57 ± 11.8 years, and 7 patients aged 8 - 12 years. There were 71 pelvic or calyceal solitary stones, 62 non-complete staghorn stones, 17 ureteral stones, 32 renal + ureteric stones (simultaneous renal and ureteral stones) , and 28 complete staghorn stones. The average stone size was 3.5 ± 2.8 (range: 0.7 to 11.8 cm). Results: The mean operation duration was 85.0 ± 29.4 min, and the mean hospital stay was 21.7 ± 3.4 h. Out of 210 patients, 6 patients had longer stay due to high-grade fever and 3 patients due to severe pain, and also 7 patients refused discharge due to personal and social reasons. Our ambulatory PCNL rate was 97 % ( 194 out of 210). Within 72 h, 5 patients were readmitted due to high-grade fever, 3 patients due to haematuria, and 4 patients due to pain and dysuria, and all patients were discharged 2 - 4 days after conservative treatment. Thus, the readmission rate was 6.18% (12 cases were readmitted out of 194 cases). Patients showed a blood transfusion rate of 1.4 %. Also, 19 cases (9.02%) were found with post-operative fever, and no urosepsis was reported. No pulmonary complications and mortality were noted. No re-exploration was done, and no major leak was noted. The angio-embolization rate was 0.59%. We did not use HEMO-SEAL technology, cautery, or suture in the tracks. Conclusions: In conclusion, the outpatient PCNL procedure is an applicable and feasible procedure under selected criteria; however, more investigations using a larger sample size are needed.

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