Effect of Solutes on Grain Refinement of As-Cast Fe-4Si Alloy

NASA Astrophysics Data System (ADS)

Li, Ming; Li, Jian-Min; Zheng, Qing; Wang, Geoff; Zhang, Ming-Xing

2018-06-01

Grain size is one of the key microstructural factors that control the mechanical properties of steels. The present work aims to extend the theories of grain refinement which were established for cast light alloys to steel systems. Using a designed Fe-4 wt pct Si alloy (all-ferrite structure during whole solidification process), the solute effect on grain refinement/grain coarsening in ferritic systems was comprehensively investigated. Experimental results showed that boron (B), which is associated with the highest Q value (growth restriction factor) in ferrite, significantly refined the as-cast structure of the Fe-4 wt pct Si alloy. Cu and Mo with low Q values had no effect on grain refinement. However, although Y and Zr have relatively high Q values, addition of these two solutes led to grain coarsening in the Fe-4Si alloy. Understanding the results in regards to the growth restriction factor and the driving force for the solidification led to the conclusion that in addition to the grain growth restriction effect, the changes of thermodynamic driving force for solidification due to the solute addition also played a key role in grain refinement in ferritic alloys.

Effect of Solutes on Grain Refinement of As-Cast Fe-4Si Alloy

NASA Astrophysics Data System (ADS)

Li, Ming; Li, Jian-Min; Zheng, Qing; Wang, Geoff; Zhang, Ming-Xing

2018-03-01

Grain size is one of the key microstructural factors that control the mechanical properties of steels. The present work aims to extend the theories of grain refinement which were established for cast light alloys to steel systems. Using a designed Fe-4 wt pct Si alloy (all-ferrite structure during whole solidification process), the solute effect on grain refinement/grain coarsening in ferritic systems was comprehensively investigated. Experimental results showed that boron (B), which is associated with the highest Q value (growth restriction factor) in ferrite, significantly refined the as-cast structure of the Fe-4 wt pct Si alloy. Cu and Mo with low Q values had no effect on grain refinement. However, although Y and Zr have relatively high Q values, addition of these two solutes led to grain coarsening in the Fe-4Si alloy. Understanding the results in regards to the growth restriction factor and the driving force for the solidification led to the conclusion that in addition to the grain growth restriction effect, the changes of thermodynamic driving force for solidification due to the solute addition also played a key role in grain refinement in ferritic alloys.

Grain refinement of high strength steels to improve cryogenic toughness

NASA Technical Reports Server (NTRS)

Rush, H. F.

1985-01-01

Grain-refining techniques using multistep heat treatments to reduce the grain size of five commercial high-strength steels were investigated. The goal of this investigation was to improve the low-temperature toughness as measured by Charpy V-notch impact test without a significant loss in tensile strength. The grain size of four of five alloys investigated was successfully reduced up to 1/10 of original size or smaller with increases in Charpy impact energy of 50 to 180 percent at -320 F. Tensile properties were reduced from 0 to 25 percent for the various alloys tested. An unexpected but highly beneficial side effect from grain refining was improved machinability.

Effect of Al on Grain Refinement and Mechanical Properties of Mg-3Nd Casting Alloy

NASA Astrophysics Data System (ADS)

Wang, Lei; Feng, Yicheng; Wang, Liping; Chen, Yanhong; Guo, Erjun

2018-05-01

The effect of Al on the grain refinement and mechanical properties of as-cast Mg-3Nd alloy was investigated systematically by a series of microstructural analysis, solidification analysis and tensile tests. The results show that Al has an obvious refining effect on the as-cast Mg-3Nd alloy. With increasing Al content, the grain size of the as-cast Mg-3Nd alloy decreases firstly, then increases slightly after the Al content reaching 3 wt.%, and the minimum grain size of the Mg-3Nd alloy is 48 ± 4.0 μm. The refining mechanism can be attributed to the formation of Al2Nd particles, which play an important role in the heterogeneous nucleation. The strength and elongation of the Mg-3Nd alloy refined by Al also increase with increasing Al content and slightly decrease when the Al content is more than 3 wt.%, and the strengthening mechanism is attributed to the grain refinement as well as dispersed intermetallic particles. Furthermore, the microstructural thermal stability of the Mg-3Nd-3Al alloy is higher than that of the Mg-3Nd-0.5Zr alloy. Overall, the Mg-3Nd alloy with Al addition is a novel alloy with wide and potential application prospects.

Effect of Grain Refining on Defect Formation in DC Cast Al-Zn-Mg-Cu Alloy Billet

NASA Astrophysics Data System (ADS)

Nadella, Ravi; Eskin, Dmitry; Katgerman, Laurens

In direct chill (DC) casting, the effect of grain refining on the prominent defects such as hot cracking and macrosegregation remains poorly understood, especially for multi-component commercial aluminum alloys. In this work, DC casting experiments were conducted on a 7075 alloy with and without grain refining at two casting speeds. The grain refiner was introduced either in the launder or in the furnace. The concentration profiles of Zn, Cu and Mg, measured along the billet diameter, showed that the increasing casting speed raises the segregation levels but grain refining does not seem to have a noticeable effect. However, hot cracking tendency is significantly reduced with grain refining and it is observed that crack is terminated with the introduction of grain refiner at a lower casting speed. These experimental results are correlated with microstructural observations such as grain size and morphology, and the occurrence of floating grains.

A Comparison of the Behaviour of AlTiB and AlTiC Grain Refiners

NASA Astrophysics Data System (ADS)

Schneider, W.; Kearns, M. A.; McGarry, M. J.; Whitehead, A. J.

AlTiC master alloys present a new alternative to AlTiB grain refiners which have enjoyed pre-eminence in cast houses for several decades. Recent investigations have shown that, under defined casting conditions, AlTiC is a more efficient grain refiner than AlTiB, is less prone to agglomeration and is more resistant to poisoning by Zr, Cr. Moreover it is observed that there are differences in the mechanism of grain refinement for the different alloys. This paper describes the influence of melt temperature and addition rate on the performance of both types of grain refiner in DC casting tests on different wrought alloys. Furthermore the effects of combined additions of the grain refiners and the recycling behaviour of the treated alloys are presented. Results are compared with laboratory test data. Finally, mechanisms of grain refinement are discussed which are consistent with the observed differences in behaviour with AlTiC and AlTiB.

Grain refinement of cast zinc through magnesium inoculation: Characterisation and mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zhilin; Qiu, Dong; Wang, Feng

2015-08-15

It was previously found that peritectic-forming solutes are more favourable for the grain refinement of cast Al alloys than eutectic-forming solutes. In this work, we report that the eutectic-forming solute, Mg, can also significantly grain refine cast Zn. Differential thermal analysis (DTA) of a Zn–Mg alloy, in which efficient grain refinement occurred, evidenced an unexpected peak that appeared before the nucleation of η-Zn grains on the DTA spectrum. Based on extensive examination using X-ray diffraction, high resolution SEM and EDS, it was found that: (a) some faceted Zn–Mg intermetallic particles were reproducibly observed; (b) the particles were located at ormore » near grain centres; (c) the atomic ratio of Mg to Zn in the intermetallic compound was determined to be around 1/2. Using tilting selected area diffraction (SAD) and convergent beam Kikuchi line diffraction pattern (CBKLDP) techniques, these faceted particles were identified as MgZn{sub 2} and an orientation relationship between such grain-centred MgZn{sub 2} particles and the η-Zn matrix was determined. Hence, the unexpected peak on the DTA spectrum is believed to correspond to the formation of MgZn{sub 2} particles, which act as effective heterogeneous nucleation sites in the alloy. Together with the effect of Mg solute on restricting grain growth, such heterogeneous nucleation is cooperatively responsible for the grain size reduction in Zn–Mg alloys. - Highlights: • A new eutectic-based grain refiner for the cast Zn was found. • The formation process of an intermetallic compound (MgZn{sub 2}) was characterised. • MgZn{sub 2} can act as potent heterogeneous nucleation sites above the liquidus. • A new OR between MgZn{sub 2} and η-Zn was determined using the CBKLDP technique.« less

Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

NASA Astrophysics Data System (ADS)

Apparao, K. Ch; Birru, Anil Kumar

2018-01-01

A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

Dietary modeling shows that substitution of whole-grain for refined-grain ingredients of foods commonly consumed by US children and teens can increase intake of whole grains.

PubMed

Keast, Debra R; Rosen, Renee A; Arndt, Elizabeth A; Marquart, Len F

2011-09-01

Currently available whole-grain foods are not frequently consumed, and few children achieve the whole-grain intake recommendation. To investigate the influence on whole-grain consumption of substituting whole-grain for refined-grain ingredients of foods commonly consumed by children. Secondary cross-sectional analysis of publicly available food consumption data collected by the US Department of Agriculture. A nationally representative sample of US children aged 9 to 18 years (n=2,349) providing 24-hour dietary recall data in the 2003-2004 National Health and Nutrition Examination Survey. Whole-grain intake was modeled by replacing varying proportions of refined flour contained in foods such as pizza crust, pasta, breads, and other baked goods with whole-wheat flour, and by replacing a proportion of white rice with brown rice. Replacement levels were based on the acceptability of whole-grain foods tested among children in elementary schools, and ranged from 15% to 50%; the majority were ≤25%. Sample-weighted mean premodeled and postmodeled whole-grain intake, standard errors, and statistical significance of differences between demographic subgroups were determined using SUDAAN (version 9.0.3, 2007, Research Triangle Institute, Research Triangle Park, NC). Whole-grain intake increased 1.7 oz eq per day (from 0.5 to 2.2 oz eq/day). Premodeled and postmodeled whole-grain intakes were 6% and 28%, respectively, of total grain intake (7.7 oz eq/day). Major sources of postmodeled whole-grain intakes were breads/rolls (28.0%); pizza (14.2%); breakfast cereals (11.0%); rice/pasta (10.6%); quick breads such as tortillas, muffins, and waffles (10.8%); other baked goods (9.9%); and grain-based savory snacks other than popcorn (7.3%). Premodeled whole-grain intake differed by poverty level, but postmodeled whole-grain intake did not. The substitution of whole grain for a specific proportion of refined grain ingredients of commonly consumed foods increased whole-grain intake

Grain refinement and texture development of cast bismuth-antimony alloy via severe plastic deformation

NASA Astrophysics Data System (ADS)

Im, Jae-Taek

The purpose of this work was to study learn about grain refinement mechanisms and texture development in cast n-type Bi90Sb10 alloy caused by severe plastic deformation. The practical objective is to produce a fine grained and textured microstructure in Bi90Sb10 alloy with enhanced thermoelectric performance and mechanical strength. In the study, twelve millimeter diameter cast bars of Bi90Sb 10 alloy were encapsulated in square cross section aluminum 6061 alloy containers. The composite bars were equal channel angular (ECAE) extruded through a 90 degree angle die at high homologous temperature. Various extrusion conditions were studied including punch speed (0.1, 0.3 and 0.6 in/min), extrusion temperature (220, 235 and 250°C), number of extrusion passes (1, 2 and 4), route (A, BC and C), and exit channel area reduction ratio (half and quarter area of inlet channel). The affect of an intermediate long term heat treatment (for 100 hours at 250°C under 10-3 torr vacuum) was explored. Processed materials were characterized by optical microscopy, x-ray diffraction, energy dispersive spectroscopy, wavelength dispersive spectroscopy and scanning electron microscopy. Texture was analyzed using the {006} reflection plane to identify the orientation of the basal poles in processed materials. The cast grains were irregularly shaped, had a grain size of hundreds-of-microns to millimeters, and showed inhomogeneous chemical composition. Severe plastic deformation refines the cast grains through dynamic recrystallization and causes the development of a bimodal microstructure consisting of fine grains (5-30 micron) and coarse grains (50-300 micron). ECAE processing of homogenizied Bi-Sb alloy causes grain refinement and produces a more uniform microstructure. Texture results show that ECAE route C processing gives a similar or slightly stronger texture than ECAE route A processing. In both cases, the basal-plane poles become aligned with the shear direction. Reduction area exit

Consumption of Whole Grains, Refined Cereals, and Legumes and Its Association With Colorectal Cancer Among Jordanians

PubMed Central

Tayyem, Reema F.; Bawadi, Hiba A.; Shehadah, Ihab; Agraib, Lana M.; Al-Awwad, Narmeen J.; Heath, Dennis D.; Bani-Hani, Kamal E.

2015-01-01

Background. The role of whole grains, refined cereals, and legumes in preventing or initiating colorectal cancer (CRC) is still uncertain. The aim of this study is to examine the possible association between the consumption of whole grains, refined cereals, and legumes and the risk of developing CRC among Jordanian population. Methods. A validated food frequency questionnaire was used to collect dietary data with regard to intake of whole grains, refined cereals, and legumes. A total of 220 diagnosed CRC participants and 281 CRC-free control participants matched by age, gender, occupation, and marital status were recruited. Logistic regression was used to estimate the odds of developing CRC in relation to the consumption of different types of whole grains, refined cereals, and legumes. Results. The odds ratio (OR) for developing CRC among cases consumed refined wheat bread at all meals was 3.1 compared with controls (95% CI: 1.2-7.9, P-Trend = 0.001); whereas the OR associated with whole wheat bread was 0.44 (95% CI: 0.22-0.92, P-Trend = 0.001). The statistical evaluation for daily consumption of rice suggested a direct association with the risk of developing CRC, OR = 3.0 (95% CI: 0.27-33.4, P-Trend = 0.020). Weekly consumption of macaroni was associated with CRC with OR of 2.4 (95% CI: 1.1-5.3, P-Trend = 0.001). The consumption of corn, bulgur, lentils, and peas suggested a protective trend, although the trend was not statistically significant. Conclusion. This study provides additional indicators of the protective role of whole grains and suggests a direct association between consumption of refined grains and higher possibility for developing CRC. PMID:26631260

Grain Refinement of AZ31 Magnesium Alloy Weldments by AC Pulsing Technique

NASA Astrophysics Data System (ADS)

Kishore Babu, N.; Cross, C. E.

2012-11-01

The current study has investigated the influence of alternating current pulsing on the structure and mechanical properties of AZ31 magnesium alloy gas tungsten arc (GTA) weldments. Autogenous full penetration bead-on-plate GTA welds were made under a variety of conditions including variable polarity (VP), variable polarity mixed (VPM), alternating current (AC), and alternating current pulsing (ACPC). AC pulsing resulted in significant refinement of weld metal when compared with the unpulsed conditions. AC pulsing leads to relatively finer and more equiaxed grain structure in GTA welds. In contrast, VP, VPM, and AC welding resulted in predominantly columnar grain structures. The reason for this grain refinement may be attributed to the periodic variations in temperature gradient and solidification rate associated with pulsing as well as weld pool oscillation observed in the ACPC welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, tensile strength, and ductility.

No effect of 14 day consumption of whole grain diet compared to refined grain diet on antioxidant measures in healthy, young subjects: a pilot study.

PubMed

Enright, Lynda; Slavin, Joanne

2010-03-19

Epidemiological evidence supports that a diet high in whole grains is associated with lowered risk of chronic diseases included coronary heart disease, obesity, type 2 diabetes, and some types of cancer. One potential mechanism for the protective properties of whole grains is their antioxidant content. The aim of this study was to compare differences in antioxidant measures when subjects consumed either refined or whole grain diets. Twenty healthy subjects took part in a randomized, crossover dietary intervention study. Subjects consumed either a refined grain or whole grain diet for 14 days and then the other diet for the next 14 days. Male subjects consumed 8 servings of grains per day and female subjects consumed 6 servings of grains per day. Blood and urine samples were collected at the end of each diet. Antioxidant measures included oxygen radical absorbance capacity (ORAC) in blood, and isoprostanes and thiobarbituric acid reactive substances (TBARS) in urine. The whole grain diet was significantly higher in dietary fiber, vitamin B6, folate, selenium, copper, zinc, iron, magnesium and cystine compared to the refined grain diet. Despite high intakes of whole grains, no significant differences were seen in any of the antioxidant measures between the refined and whole grain diets. No differences in antioxidant measures were found when subjects consumed whole grain diets compared to refined grain diets.

Influence of Aluminum Content on Grain Refinement and Strength of AZ31 Magnesium GTA Weld Metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, N. Kishore; Cross, Carl E.

2012-06-28

The goal is to characterize the effect of Al content on AZ31 weld metal, the grain size and strength, and examine role of Al on grain refinement. The approach is to systematically vary the aluminum content of AZ31 weld metal, Measure average grain size in weld metal, and Measure cross-weld tensile properties and hardness. Conclusions are that: (1) increased Al content in AZ31 weld metal results in grain refinement Reason: higher undercooling during solidification; (2) weld metal grain refinement resulted in increased strength & hardness Reason: grain boundary strengthening; and (3) weld metal strength can be raised to wrought basemore » metal levels.« less

Refinement of the β-Sn Grains in Ni-Doped Sn-3.0Ag-0.5Cu Solder Joints with Cu-Based and Ni-Based Substrates

NASA Astrophysics Data System (ADS)

Chou, Tzu-Ting; Chen, Wei-Yu; Fleshman, Collin Jordon; Duh, Jenq-Gong

2018-03-01

A fine-grain structure with random orientations of lead-free solder joints was successfully obtained in this study. The Sn-Ag-Cu solder alloys doped with minor Ni were reflowed with Ni-based or Cu-based substrates to fabricate the joints containing different Ni content. Adding 0.1 wt.% Ni into the solder effectively promoted the formation of fine Sn grains, and reflowing with Ni-based substrates further enhanced the effects of β-Sn grain refinement. The crystallographic characteristics and the microstructures were analyzed to identify the solidification mechanism of different types of microstructure in the joints. The phase precipitating order in the joint altered as the solder composition were modified by elemental doping and changing substrate, which significantly affected the efficiency of grain refinement and the final grain structure. The formation mechanism of fine β-Sn grains in the Ni-doped joint with a Ni-based substrate is attributable to the heterogeneous nucleation by Ni, whereas the Ni in the joint using ChouCu-based substrate is consumed to form an intermetallic compound and thus retard the effect of grain refining.

Grain Refinement of Freeform Fabricated Ti-6Al-4V Alloy Using Beam/Arc Modulation

NASA Technical Reports Server (NTRS)

Mitzner, Scott; Liu, Stephen; Domack, Marcia S.; Hafley, Robert A.

2012-01-01

Grain refinement can significantly improve the mechanical properties of freeform-fabricated Ti-6Al-4V alloy, promoting increased strength and enhanced isotropy compared with coarser grained material. Large beta-grains can lead to a segregated microstructure, in regard to both alpha-phase morphology and alpha-lath orientation. Beam modulation, which has been used in conventional fusion welding to promote grain refinement, is explored in this study for use in additive manufacturing processes including electron beam freeform fabrication (EBF(sup 3)) and gas-tungsten arc (GTA) deposition to alter solidification behavior and produce a refined microstructure. The dynamic molten pool size induced by beam modulation causes rapid heat flow variance and results in a more competitive grain growth environment, reducing grain size. Consequently, improved isotropy and strength can be achieved with relatively small adjustments to deposition parameters.

Precipitation process in a Mg–Gd–Y alloy grain-refined by Al addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Jichun; CAST Cooperative Research Centre, Department of Materials Engineering, Monash University, Victoria 3800; Zhu, Suming, E-mail: suming.zhu@monash.edu

2014-02-15

The precipitation process in Mg–10Gd–3Y (wt.%) alloy grain-refined by 0.8 wt.% Al addition has been investigated by transmission electron microscopy. The alloy was given a solution treatment at 520 °C for 6 h plus 550 °C for 7 h before ageing at 250 °C. Plate-shaped intermetallic particles with the 18R-type long-period stacking ordered structure were observed in the solution-treated state. Upon isothermal ageing at 250 °C, the following precipitation sequence was identified for the α-Mg supersaturated solution: β″ (D0{sub 19}) → β′ (bco) → β{sub 1} (fcc) → β (fcc). The observed precipitation process and age hardening response in themore » Al grain-refined Mg–10Gd–3Y alloy are compared with those reported in the Zr grain-refined counterpart. - Highlights: • The precipitation process in Mg–10Gd–3Y–0.8Al (wt.%) alloy has been investigated. • Particles with the 18R-type LPSO structure were observed in the solution state. • Upon ageing at 250 °C, the precipitation sequence is: β″ → β′ → β1 (fcc) → β. • The Al grain-refined alloy has a lower hardness than the Zr refined counterpart.« less

Refinement of Ferrite Grain Size near the Ultrafine Range by Multipass, Thermomechanical Compression

NASA Astrophysics Data System (ADS)

Patra, S.; Neogy, S.; Kumar, Vinod; Chakrabarti, D.; Haldar, A.

2012-11-01

Plane-strain compression testing was carried out on a Nb-Ti-V microalloyed steel, in a GLEEBLE3500 simulator using a different amount of roughing, intermediate, and finishing deformation over the temperature range of 1373 K to 1073 K (1100 °C to 800 °C). A decrease in soaking temperature from 1473 K to 1273 K (1200 °C to 1000 °C) offered marginal refinement in the ferrite ( α) grain size from 7.8 to 6.6 μm. Heavy deformation using multiple passes between A e3 and A r3 with true strain of 0.8 to 1.2 effectively refined the α grain size (4.1 to 3.2 μm) close to the ultrafine size by dynamic-strain-induced austenite ( γ) → ferrite ( α) transformation (DSIT). The intensities of microstructural banding, pearlite fraction in the microstructure (13 pct), and fraction of the harmful "cube" texture component (5 pct) were reduced with the increase in finishing deformation. Simultaneously, the fractions of high-angle (>15 deg misorientation) boundaries (75 to 80 pct), beneficial gamma-fiber (ND//<111>) texture components, along with {332}<133> and {554}<225> components were increased. Grain refinement and the formation of small Fe3C particles (50- to 600-nm size) increased the hardness of the deformed samples (184 to 192 HV). For the same deformation temperature [1103 K (830 °C)], the difference in α-grain sizes obtained after single-pass (2.7 μm) and multipass compression (3.2 μm) can be explained in view of the static- and dynamic-strain-induced γ → α transformation, strain partitioning between γ and α, dynamic recovery and dynamic recrystallization of the deformed α, and α-grain growth during interpass intervals.

Grain Refining and Microstructural Modification during Solidification.

DTIC Science & Technology

1983-10-01

was found to be insensitive to the iron concentration in the samples solidified in the levitated state but not in samples quenched from the liquid . The... liquid . The preliminary * results with niobium additions indicate that no appreciable grain refinement * is achieved when the samples are levitated in an...to the critical examination of the Cr-Ni phase diagram, by using high purity starting materials, and a containerless electromagnetic levitation

Time evolution as refining, coarse graining and entangling

NASA Astrophysics Data System (ADS)

Dittrich, Bianca; Steinhaus, Sebastian

2014-12-01

We argue that refining, coarse graining and entangling operators can be obtained from time evolution operators. This applies in particular to geometric theories, such as spin foams. We point out that this provides a construction principle for the physical vacuum in quantum gravity theories and more generally allows construction of a (cylindrically) consistent continuum limit of the theory.

Grain-Refined AZ92 Alloy with Superior Strength and Ductility

NASA Astrophysics Data System (ADS)

Lee, Jong Un; Kim, Sang-Hoon; Jo, Wan-Kuen; Hong, Won-Hwa; Kim, Woong; Bae, Jun Ho; Park, Sung Hyuk

2018-03-01

Grain-refined AZ92 (GR-AZ92) alloy with superior tensile properties is developed by adding 1 wt% Zn and a very small amount of SiC (0.17 wt%) to commercial AZ91 alloy for enhancing the solid-solution strengthening effect and refining the crystal grains, respectively. The homogenized GR-AZ92 alloy with an average grain size of 91 μm exhibits a tensile yield strength (TYS) of 125 MPa, ultimate tensile strength (UTS) of 281 MPa, and elongation of 12.1%, which are significantly higher than those of AZ91 alloy with a grain size of 420 μm (TYS of 94 MPa, UTS of 192 MPa, and elongation of 7.0%). The peak-aging time of GR-AZ92 alloy (8 h) is significantly shorter than that of AZ91 alloy (32 h) owing to a larger amount of grain boundaries in the former, which serve as nucleation sites of Mg17Al12 precipitates. A short-aging treatment for less than 1 h of the GR-AZ92 alloy causes an effective improvement in its strength without a significant reduction in its ductility. The 30-min-aged GR-AZ92 alloy has an excellent combination of strength and ductility, with a TYS of 142 MPa, UTS of 304 MPa, and elongation of 8.0%.

Differential Effects of Red Meat/Refined Grain Diet and Dairy/Chicken/Nuts/Whole Grain Diet on Glucose, Insulin and Triglyceride in a Randomized Crossover Study

PubMed Central

Kim, Yoona; Keogh, Jennifer B.; Clifton, Peter M.

2016-01-01

Epidemiological studies suggest that a diet high in processed meat, with a high glycemic index is associated with an increased risk of type 2 diabetes. It is not clear if this is due to altered insulin sensitivity or an enhanced postprandial glucose. We aimed to compare the acute metabolic response of two different types of meals after ingestion of the matching diet for four weeks. The study was a randomized, crossover acute meal study. Volunteers consumed either a red meat/refined grain meal or a dairy/chicken/nuts/wholegrain meal after four weeks of the matching diet. After a three-week washout period and four weeks of the alternate diet, they consumed the matching meal. The diets differed with respect to both protein and carbohydrate sources. Blood samples were taken for 180 min for the measurement of glucose, insulin, C-peptide and triglyceride. Fifty-one participants (age: 35.1 ± 15.6 years; body mass index: 27.7 ± 6.9 kg/m2, 17 with normal and 34 with impaired glucose tolerance) completed two meal tests. The area under the curve (p < 0.001) and incremental area under the curve (p = 0.001) for insulin was significantly higher after the red meat/refined grain diet than after the dairy/chicken/nuts/whole grain diet. There was an interaction between meal and glucose tolerance group (p < 0.05) in the area under the curve (AUC) and the incremental area under the curve (iAUC) of glucose; the red meat/refined grain diet increased glucose relative to the dairy/chicken/nuts/whole grain diet only in the normal group (+2.5 mmol/L/3 h). The red meat/refined grain diet increased glucose and insulin responses compared with the dairy/chicken/nuts/whole grain diet. This meal pattern would increase pancreatic stress long term and may account for the increased risk of type 2 diabetes with this diet. PMID:27809219

Differential Effects of Red Meat/Refined Grain Diet and Dairy/Chicken/Nuts/Whole Grain Diet on Glucose, Insulin and Triglyceride in a Randomized Crossover Study.

PubMed

Kim, Yoona; Keogh, Jennifer B; Clifton, Peter M

2016-10-30

Epidemiological studies suggest that a diet high in processed meat, with a high glycemic index is associated with an increased risk of type 2 diabetes. It is not clear if this is due to altered insulin sensitivity or an enhanced postprandial glucose. We aimed to compare the acute metabolic response of two different types of meals after ingestion of the matching diet for four weeks. The study was a randomized, crossover acute meal study. Volunteers consumed either a red meat/refined grain meal or a dairy/chicken/nuts/wholegrain meal after four weeks of the matching diet. After a three-week washout period and four weeks of the alternate diet, they consumed the matching meal. The diets differed with respect to both protein and carbohydrate sources. Blood samples were taken for 180 min for the measurement of glucose, insulin, C-peptide and triglyceride. Fifty-one participants (age: 35.1 ± 15.6 years; body mass index: 27.7 ± 6.9 kg/m², 17 with normal and 34 with impaired glucose tolerance) completed two meal tests. The area under the curve ( p < 0.001) and incremental area under the curve ( p = 0.001) for insulin was significantly higher after the red meat/refined grain diet than after the dairy/chicken/nuts/whole grain diet. There was an interaction between meal and glucose tolerance group ( p < 0.05) in the area under the curve (AUC) and the incremental area under the curve (iAUC) of glucose; the red meat/refined grain diet increased glucose relative to the dairy/chicken/nuts/whole grain diet only in the normal group (+2.5 mmol/L/3 h). The red meat/refined grain diet increased glucose and insulin responses compared with the dairy/chicken/nuts/whole grain diet. This meal pattern would increase pancreatic stress long term and may account for the increased risk of type 2 diabetes with this diet.

Grain Refinement of Magnesium Alloys: A Review of Recent Research, Theoretical Developments, and Their Application

NASA Astrophysics Data System (ADS)

StJohn, D. H.; Easton, M. A.; Qian, M.; Taylor, J. A.

2013-07-01

This paper builds on the "Grain Refinement of Mg Alloys" published in 2005 and reviews the grain refinement research on Mg alloys that has been undertaken since then with an emphasis on the theoretical and analytical methods that have been developed. Consideration of recent research results and current theoretical knowledge has highlighted two important factors that affect an alloy's as-cast grain size. The first factor applies to commercial Mg-Al alloys where it is concluded that impurity and minor elements such as Fe and Mn have a substantially negative impact on grain size because, in combination with Al, intermetallic phases can be formed that tend to poison the more potent native or deliberately added nucleant particles present in the melt. This factor appears to explain the contradictory experimental outcomes reported in the literature and suggests that the search for a more potent and reliable grain refining technology may need to take a different approach. The second factor applies to all alloys and is related to the role of constitutional supercooling which, on the one hand, promotes grain nucleation and, on the other hand, forms a nucleation-free zone preventing further nucleation within this zone, consequently limiting the grain refinement achievable, particularly in low solute-containing alloys. Strategies to reduce the negative impact of these two factors are discussed. Further, the Interdependence model has been shown to apply to a broad range of casting methods from slow cooling gravity die casting to fast cooling high pressure die casting and dynamic methods such as ultrasonic treatment.

Grain refinement of a nickel and manganese free austenitic stainless steel produced by pressurized solution nitriding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadzadeh, Roghayeh, E-mail: r_mohammadzadeh@sut.ac.ir; Akbari, Alireza, E-mail: akbari@sut.ac.ir

2014-07-01

Prolonged exposure at high temperatures during solution nitriding induces grain coarsening which deteriorates the mechanical properties of high nitrogen austenitic stainless steels. In this study, grain refinement of nickel and manganese free Fe–22.75Cr–2.42Mo–1.17N high nitrogen austenitic stainless steel plates was investigated via a two-stage heat treatment procedure. Initially, the coarse-grained austenitic stainless steel samples were subjected to an isothermal heating at 700 °C to be decomposed into the ferrite + Cr{sub 2}N eutectoid structure and then re-austenitized at 1200 °C followed by water quenching. Microstructure and hardness of samples were characterized using X-ray diffraction, optical and scanning electron microscopy, andmore » micro-hardness testing. The results showed that the as-solution-nitrided steel decomposes non-uniformly to the colonies of ferrite and Cr{sub 2}N nitrides with strip like morphology after isothermal heat treatment at 700 °C. Additionally, the complete dissolution of the Cr{sub 2}N precipitates located in the sample edges during re-austenitizing requires longer times than 1 h. In order to avoid this problem an intermediate nitrogen homogenizing heat treatment cycle at 1200 °C for 10 h was applied before grain refinement process. As a result, the initial austenite was uniformly decomposed during the first stage, and a fine grained austenitic structure with average grain size of about 20 μm was successfully obtained by re-austenitizing for 10 min. - Highlights: • Successful grain refinement of Fe–22.75Cr–2.42Mo–1.17N steel by heat treatment • Using the γ → α + Cr{sub 2}N reaction for grain refinement of a Ni and Mn free HNASS • Obtaining a single phase austenitic structure with average grain size of ∼ 20 μm • Incomplete dissolution of Cr{sub 2}N during re-austenitizing at 1200 °C for long times • Reducing re-austenitizing time by homogenizing treatment before grain refinement.« less

Study of Ferrite During Refinement of Prior Austenite Grains in Microalloyed Steel Continuous Casting

NASA Astrophysics Data System (ADS)

Liu, Jiang; Wen, Guanghua; Tang, Ping

2017-12-01

The formation of coarse prior austenite grain is a key factor to promote transverse crack, and the susceptibility to the transverse crack can be reduced by refining the austenite grain size. In the present study, the high-temperature confocal laser scanning microscope (CLSM) was used to simulate two types of double phase-transformation technologies. The distribution and morphology of ferrites under different cooling conditions were analyzed, and the effects of ferrite distribution and morphology on the double phase-transformation technologies were explored to obtain the suitable double phase-change technology for the continuous casting process. The results indicate that, under the thermal cycle TH0 [the specimens were cooled down to 913 K (640 °C) at a cooling rate of 5.0 K/s (5.0 °C/s)], the width of prior austenite grain boundaries was thick, and the dislocation density at grain boundaries was high. It had strong inhibition effect on crack propagation; under the thermal cycle TH1 [the specimens were cooled down to 1073 K (800 °C) at a cooling rate of 5.0 K/s (5.0 °C/s) and then to 913 K (640 °C) at a cooling rate of 1.0 K/s (1.0 °C/s)], the width of prior austenite grain boundary was thin, and the dislocation density at grain boundaries was low. It was beneficial to crack propagation. After the first phase change, the developed film-like ferrite along the austenite grain boundaries improved the nucleation conditions of new austenitic grains and removed the inhibition effect of the prior austenite grain boundaries on the austenite grain size.

The Role of Carbon in Grain Refinement of Cast CrFeCoNi High-Entropy Alloys

NASA Astrophysics Data System (ADS)

Liu, X. W.; Liu, L.; Liu, G.; Wu, X. X.; Lu, D. H.; Yao, J. Q.; Jiang, W. M.; Fan, Z. T.; Zhang, W. B.

2018-03-01

As a promising engineering material, high-entropy alloys (HEAs) CrFeCoNi system has attracted extensive attention worldwide. Their cast alloys are of great importance because of their great formability of complex components, which can be further improved through the transition of the columnar to equiaxed grains and grain refinement. In the current work, the influence of C contents on the grain structures and mechanical properties of the as-cast high-entropy alloy CrFeCoNi was chosen as the target and systematically studied via a hybrid approach of the experiments and thermodynamic calculations. The alloys with various C additions were prepared by arc melting and drop cast. The as-cast macrostructure and microstructure were characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The cast HEAs transform from coarse columnar grains into equiaxed grains with the C level increased to ≥ 2 at. pct and the size of equiaxed grains is further decreased with the increasing C addition. It is revealed that the interdendritic segregation of Cr and C results in grain boundary precipitation of M23C6 carbides. The grain refinement is attributed to the additional constitutional supercoiling from the C addition. The yield stress and tensile strength at room temperature are improved due to the transition of columnar to equiaxed grains and grain refinement.

The Role of Carbon in Grain Refinement of Cast CrFeCoNi High-Entropy Alloys

NASA Astrophysics Data System (ADS)

Liu, X. W.; Liu, L.; Liu, G.; Wu, X. X.; Lu, D. H.; Yao, J. Q.; Jiang, W. M.; Fan, Z. T.; Zhang, W. B.

2018-06-01

As a promising engineering material, high-entropy alloys (HEAs) CrFeCoNi system has attracted extensive attention worldwide. Their cast alloys are of great importance because of their great formability of complex components, which can be further improved through the transition of the columnar to equiaxed grains and grain refinement. In the current work, the influence of C contents on the grain structures and mechanical properties of the as-cast high-entropy alloy CrFeCoNi was chosen as the target and systematically studied via a hybrid approach of the experiments and thermodynamic calculations. The alloys with various C additions were prepared by arc melting and drop cast. The as-cast macrostructure and microstructure were characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The cast HEAs transform from coarse columnar grains into equiaxed grains with the C level increased to ≥ 2 at. pct and the size of equiaxed grains is further decreased with the increasing C addition. It is revealed that the interdendritic segregation of Cr and C results in grain boundary precipitation of M23C6 carbides. The grain refinement is attributed to the additional constitutional supercoiling from the C addition. The yield stress and tensile strength at room temperature are improved due to the transition of columnar to equiaxed grains and grain refinement.

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

NASA Astrophysics Data System (ADS)

Wang, Gui; Wang, Eric Qiang; Prasad, Arvind; Dargusch, Matthew; StJohn, David H.

Al-Si alloys are widely used in automotive and aerospace industries due to their excellent castability, high strength to weight ratio and good corrosion resistance. However, Si poisoning severely limits the degree of grain refinement with the grain size becoming larger as the Si content increases. Generally the effect of Si poisoning is reduced by increasing the amount of master alloy added to the melt during casting. However, an alternative approach is physical grain refinement through the application of an external force (e.g. mechanical or electromagnetic stirring, intensive shearing and ultrasonic irradiation). This work compares the grain refining efficiency of three approaches to the grain refinement of a range of hypoeutectic Al-Si alloys by (i) the addition of A13Ti1B master alloy, (ii) the application of Ultrasonic Treatment (UT) and (iii) the combined addition of A13Ti1B master alloy and the application of UT.

Effect of zirconium addition on welding of aluminum grain refined by titanium plus boron

NASA Astrophysics Data System (ADS)

Zaid, A. I. O.

2014-06-01

Aluminum oxidizes freely in ordinary atmosphere which makes its welding difficult and weak, particularly it solidifies in columnar structure with large grains. Therefore, it is anticipated that the effect of addition of some grain refiners to its melt before solidification is worth while investigating as it may enhance its weldabilty and improve its mechanical strength. In this paper, the effect of addition of zirconium at a weight of 0.1% (which corresponds to the peretictic limit on the aluminum-zirconium base phase diagram) to commercially pure aluminum, grain refined by Ti+B on its weldability, using gas tungsten arc welding, GTAW, method which was formerly known as TIG. A constant current level of 30 AC Ampere was used because it removes the oxides during the welding process. Metallographic examination of the weldments of the different combinations of Al with Al and Al with its microalloys: in the heat affected zone, HAZ, and away from it was carried out and examined for HAZ width, porosity, cracks and microhardness. It was found that grain refining by Ti+B or Zr resulted in enhancement of the weldment.

Effect of Mg2Sn Intermetallic on the Grain Refinement in As-cast AM Series Alloy

NASA Astrophysics Data System (ADS)

She, J.; Pan, F. S.; Hu, H. H.; Tang, A. T.; Yu, Z. W.; Song, K.

2015-08-01

In the present work, in order to investigate the grain refinement mechanism of AM containing Sn alloys, the as-cast AM60, AM90 alloys, and the alloys with addition of 1 wt.% Sn were fabricated by traditional casting, respectively. During the solidification of AM + Sn alloys, the morphology of divorced eutectic Mg17Al12 was refined by Mg2Sn intermetallic that served as the heterogeneous nucleation cores. The modified Mg17Al12 effectively restricted the grain growth and resulted in a grain refinement. As a result, the yield strength of as-cast AM alloys was significantly enhanced by addition of Sn, while the ductility also improved. Moreover, the edge-to-edge model was employed to predict the orientation relationship between Mg17Al12 and Mg2Sn.

Substituting whole grains for refined grains in a 6-week randomized trial favorably affects energy balance parameters in healthy men and post-menopausal women

USDA-ARS?s Scientific Manuscript database

Background: The effect of whole grains on the regulation of energy balance remains controversial. Objective: To determine the effects of substituting whole grains for refined grains, independent of body weight change, on energy metabolism parameters and glycemic control. Design: A randomized, con...

Grain-refining heat treatments to improve cryogenic toughness of high-strength steels

NASA Technical Reports Server (NTRS)

Rush, H. F.

1984-01-01

The development of two high Reynolds number wind tunnels at NASA Langley Research Center which operate at cryogenic temperatures with high dynamic pressures has imposed severe requirements on materials for model construction. Existing commercial high strength steels lack sufficient toughness to permit their safe use at temperatures approaching that of liquid nitrogen (-320 F). Therefore, a program to improve the cryogenic toughness of commercial high strength steels was conducted. Significant improvement in the cryogenic toughness of commercial high strength martensitic and maraging steels was demonstrated through the use of grain refining heat treatments. Charpy impact strength at -320 F was increased by 50 to 180 percent for the various alloys without significant loss in tensile strength. The grain sizes of the 9 percent Ni-Co alloys and 200 grade maraging steels were reduced to 1/10 of the original size or smaller, with the added benefit of improved machinability. This grain refining technique should permit these alloys with ultimate strengths of 220 to 270 ksi to receive consideration for cryogenic service.

Wire Arc Additive Manufacturing of AZ31 Magnesium Alloy: Grain Refinement by Adjusting Pulse Frequency.

PubMed

Guo, Jing; Zhou, Yong; Liu, Changmeng; Wu, Qianru; Chen, Xianping; Lu, Jiping

2016-10-09

Wire arc additive manufacturing (WAAM) offers a potential approach to fabricate large-scale magnesium alloy components with low cost and high efficiency, although this topic is yet to be reported in literature. In this study, WAAM is preliminarily applied to fabricate AZ31 magnesium. Fully dense AZ31 magnesium alloy components are successfully obtained. Meanwhile, to refine grains and obtain good mechanical properties, the effects of pulse frequency (1, 2, 5, 10, 100, and 500 Hz) on the macrostructure, microstructure and tensile properties are investigated. The results indicate that pulse frequency can result in the change of weld pool oscillations and cooling rate. This further leads to the change of the grain size, grain shape, as well as the tensile properties. Meanwhile, due to the resonance of the weld pool at 5 Hz and 10 Hz, the samples have poor geometry accuracy but contain finer equiaxed grains (21 μm) and exhibit higher ultimate tensile strength (260 MPa) and yield strength (102 MPa), which are similar to those of the forged AZ31 alloy. Moreover, the elongation of all samples is above 23%.

Refining the treatment of membrane proteins by coarse-grained models.

PubMed

Vorobyov, Igor; Kim, Ilsoo; Chu, Zhen T; Warshel, Arieh

2016-01-01

Obtaining a quantitative description of the membrane proteins stability is crucial for understanding many biological processes. However the advance in this direction has remained a major challenge for both experimental studies and molecular modeling. One of the possible directions is the use of coarse-grained models but such models must be carefully calibrated and validated. Here we use a recent progress in benchmark studies on the energetics of amino acid residue and peptide membrane insertion and membrane protein stability in refining our previously developed coarse-grained model (Vicatos et al., Proteins 2014;82:1168). Our refined model parameters were fitted and/or tested to reproduce water/membrane partitioning energetics of amino acid side chains and a couple of model peptides. This new model provides a reasonable agreement with experiment for absolute folding free energies of several β-barrel membrane proteins as well as effects of point mutations on a relative stability for one of those proteins, OmpLA. The consideration and ranking of different rotameric states for a mutated residue was found to be essential to achieve satisfactory agreement with the reference data. © 2015 Wiley Periodicals, Inc.

Scaling up of High-Pressure Sliding (HPS) for Grain Refinement and Superplasticity

NASA Astrophysics Data System (ADS)

Takizawa, Yoichi; Masuda, Takahiro; Fujimitsu, Kazushige; Kajita, Takahiro; Watanabe, Kyohei; Yumoto, Manabu; Otagiri, Yoshiharu; Horita, Zenji

2016-09-01

The process of high-pressure sliding (HPS) is a method of severe plastic deformation developed recently for grain refinement of metallic materials under high pressure. The sample for HPS is used with a form of sheet or rod. In this study, an HPS facility with capacities of 500 tonnes for vertical pressing and of 500 and 300 tonnes for horizontal forward and backward pressings, respectively, was newly built and applied for grain refinement of a Mg alloy as AZ61, Al alloys such as Al-Mg-Sc, A2024 and A7075 alloys, a Ti alloy as ASTM-F1295, and a Ni-based superalloy as Inconel 718. Sheet samples with dimensions of 10 to 30 mm width, 100 mm length, and 1 mm thickness were processed at room temperature and ultrafine grains with sizes of ~200 to 300 nm were successfully produced in the alloys. Tensile testing at elevated temperatures confirmed the advent of superplasticity with total elongations of more than 400 pct in all the alloys. It is demonstrated that the HPS can make all the alloys superplastic through processing at room temperature with a form of rectangular sheets.

Study on the effect of temperature rise on grain refining during fabrication of nanocrystalline copper under explosive loading

NASA Astrophysics Data System (ADS)

Wang, Jinxiang; Yang, Rui; Jiang, Li; Wang, Xiaoxu; Zhou, Nan

2013-11-01

Nanocrystalline (NC) copper was fabricated by severe plastic deformation of coarse-grained copper at a high strain rate under explosive loading. The feasibility of grain refinement under different explosive loading and the influence of overall temperature rise on grain refinement under impact compression were studied in this paper. The calculation model for the macroscopic temperature rise was established according to the adiabatic shock compression theory. The calculation model for coarse-grained copper was established by the Voronoi method and the microscopic temperature rise resulted from severe plastic deformation of grains was calculated by ANSYS/ls-dyna finite element software. The results show that it is feasible to fabricate NC copper by explosively dynamic deformation of coarse-grained copper and the average grain size of the NC copper can be controlled between 200˜400 nm. The whole temperature rise would increase with the increasing explosive thickness. Ammonium nitrate fuel oil explosive was adopted and five different thicknesses of the explosive, which are 20 mm, 25 mm, 30 mm, 35 mm, 45 mm, respectively, with the same diameter using 20 mm to the fly plate were adopted. The maximum macro and micro temperature rise is up to 532.4 K, 143.4 K, respectively, which has no great effect on grain refinement due to the whole temperature rise that is lower than grain growth temperature according to the high pressure melting theory.

Fabrication of the Ti5Si3/Ti composite inoculants and its refining mechanism on pure titanium

NASA Astrophysics Data System (ADS)

Li, Nuo; Cui, Chunxiang; Liu, Shaungjin; Zhao, Long; Liu, Shuiqing

2017-03-01

The in situ Ti5Si3/Ti inoculants were successfully prepared by vacuum arc-melting and melt-spinning method. An efficient route by adding a small quantity of Ti5Si3/Ti inoculants to Ti melt has been first proposed to modify the coarse grains of as cast microstructure of pure titanium in this paper. It was found that the microstructure of ribbon inoculants was cellular structure that composed of Ti5Si3 and α-Ti phases. The grain refining effect of the inoculants was significantly improved with the adding ratio range from 0.2% to 0.5% in weight. With the increase of addition amount of inoculants on Ti melt, the tensile strength, yield strength and microhardness of pure titanium are significantly improved except elongation. The excellent grain refining effect can be attributed to the heterogeneous nucleation of the titanium grain on the precipitated Ti5Si3 phases in the Si-rich regions and the constitutional supercooling of Si in the Si-poverty regions. It is suggested that the in situ Ti5Si3/Ti inoculants is a promising inoculants for titanium alloys.

Investigation on temporal evolution of the grain refinement in copper under high strain rate loading via in-situ synchrotron measurement and predictive modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Pooja Nitin; Shin, Yung C.; Sun, Tao

Synchrotron X-rays are integrated with a modified Kolsky tension bar to conduct in situ tracking of the grain refinement mechanism operating during the dynamic deformation of metals. Copper with an initial average grain size of 36 μm is refined to 6.3 μm when loaded at a constant high strain rate of 1200 s -1. The synchrotron measurements revealed the temporal evolution of the grain refinement mechanism in terms of the initiation and rate of refinement throughout the loading test. A multiscale coupled probabilistic cellular automata based recrystallization model has been developed to predict the microstructural evolution occurring during dynamic deformationmore » processes. The model accurately predicts the initiation of the grain refinement mechanism with a predicted final average grain size of 2.4 μm. As a result, the model also accurately predicts the temporal evolution in terms of the initiation and extent of refinement when compared with the experimental results.« less

Investigation on temporal evolution of the grain refinement in copper under high strain rate loading via in-situ synchrotron measurement and predictive modeling

DOE PAGES

Shah, Pooja Nitin; Shin, Yung C.; Sun, Tao

2017-10-03

Synchrotron X-rays are integrated with a modified Kolsky tension bar to conduct in situ tracking of the grain refinement mechanism operating during the dynamic deformation of metals. Copper with an initial average grain size of 36 μm is refined to 6.3 μm when loaded at a constant high strain rate of 1200 s -1. The synchrotron measurements revealed the temporal evolution of the grain refinement mechanism in terms of the initiation and rate of refinement throughout the loading test. A multiscale coupled probabilistic cellular automata based recrystallization model has been developed to predict the microstructural evolution occurring during dynamic deformationmore » processes. The model accurately predicts the initiation of the grain refinement mechanism with a predicted final average grain size of 2.4 μm. As a result, the model also accurately predicts the temporal evolution in terms of the initiation and extent of refinement when compared with the experimental results.« less

Effect of Austenite Deformation on the Microstructure Evolution and Grain Refinement Under Accelerated Cooling Conditions

NASA Astrophysics Data System (ADS)

Zhao, H.; Palmiere, E. J.

2017-07-01

Although there has been much research regarding the effect of austenite deformation on accelerated cooled microstructures in microalloyed steels, there is still a lack of accurate data on boundary densities and effective grain sizes. Previous results observed from optical micrographs are not accurate enough, because, for displacive transformation products, a substantial part of the boundaries have disorientation angles below 15 deg. Therefore, in this research, a niobium microalloyed steel was used and electron backscattering diffraction mappings were performed on all of the transformed microstructures to obtain accurate results on boundary densities and grain refinement. It was found that with strain rising from 0 to 0.5, a transition from bainitic ferrite to acicular ferrite occurs and the effective grain size reduces from 5.7 to 3.1 μm. When further increasing strain from 0.5 to 0.7, dynamic recrystallization was triggered and postdynamic softening occurred during the accelerated cooling, leading to an inhomogeneous and coarse transformed microstructure. In the entire strain range, the density changes of boundaries with different disorientation angles are distinct, due to different boundary formation mechanisms. Finally, the controversial influence of austenite deformation on effective grain size of low-temperature transformation products was argued to be related to the differences in transformation conditions and final microstructures.

Wire Arc Additive Manufacturing of AZ31 Magnesium Alloy: Grain Refinement by Adjusting Pulse Frequency

PubMed Central

Guo, Jing; Zhou, Yong; Liu, Changmeng; Wu, Qianru; Chen, Xianping; Lu, Jiping

2016-01-01

Wire arc additive manufacturing (WAAM) offers a potential approach to fabricate large-scale magnesium alloy components with low cost and high efficiency, although this topic is yet to be reported in literature. In this study, WAAM is preliminarily applied to fabricate AZ31 magnesium. Fully dense AZ31 magnesium alloy components are successfully obtained. Meanwhile, to refine grains and obtain good mechanical properties, the effects of pulse frequency (1, 2, 5, 10, 100, and 500 Hz) on the macrostructure, microstructure and tensile properties are investigated. The results indicate that pulse frequency can result in the change of weld pool oscillations and cooling rate. This further leads to the change of the grain size, grain shape, as well as the tensile properties. Meanwhile, due to the resonance of the weld pool at 5 Hz and 10 Hz, the samples have poor geometry accuracy but contain finer equiaxed grains (21 μm) and exhibit higher ultimate tensile strength (260 MPa) and yield strength (102 MPa), which are similar to those of the forged AZ31 alloy. Moreover, the elongation of all samples is above 23%. PMID:28773944

Influence of nitrogen as grain refiner in low carbon and microalloyed steels

NASA Astrophysics Data System (ADS)

Hasan, B. M.; Sathyamurthy, P.

2018-02-01

Microalloyed steel is replacing using of low alloy steel in automotive industry. Microalloying elements like vanadium, niobium and titanium are used to enhance the steel property. The current work is focused on using nitrogen as a strengthening element in existing steel grade. Nitrogen in free form acts as solid solution strengthener and in combined form as precipitates acts as grain refiner for enhancing strength. The problem of grain coarsening at high temperature in case carburizing steel was avoided by increasing nitrogen level from 60ppm to 200ppm. Grain size of ASTM no 10 is obtained at carburizing temperature of 950 °C by increasing nitrogen content from grain size no 6 with lower nitrogen. Mostly crankshaft is made from Cr-Mo alloyed steel. At JSW, nitrogen in the level of 130-200ppm is added to medium carbon steel to meet property requirement for crankshaft application

The Effect of Grain Refinement on Solid Particle Erosion of Grade 5 Ti Alloy

NASA Astrophysics Data System (ADS)

Kazarinov, N. A.; Evstifeev, A. D.; Petrov, Y. V.; Atroshenko, S. A.; Valiev, R. R.

2018-04-01

In this work, the results on solid particle erosion of an ultrafine-grained Grade 5 titanium alloy, which was produced using high-pressure torsion (HPT) technique, are presented. In order to assess influence of the HPT treatment on material's behavior in erosive conditions, special experimental procedures were developed. The ultrafine-grained (UFG) alloy was tested alongside with a conventional coarse-grained (CG) Grade 5 titanium alloy in equal conditions. The experiments were conducted in a small-scale wind tunnel with corundum particles as an abrasive material. Both particle dimensions and particle velocities were varied in course of the experiments. Erosion resistance of the samples was evaluated in two ways—mass reduction measurements with subsequent gravimetric erosion rate calculations and investigation of samples' surface roughness after erosion tests. The UFG titanium alloy demonstrated considerable improvement of static mechanical properties (ultimate tensile strength, microhardness), whereas its CG counterpart appeared to be slightly more resistant to solid particle erosion, which might indicate the drop of dynamic strength properties for the HPT-processed material.

The Effects of Grain Refinement and Rare Earth Intermetallics on Mechanical Properties of As-Cast and Wrought Magnesium Alloys

NASA Astrophysics Data System (ADS)

Pourbahari, Bita; Mirzadeh, Hamed; Emamy, Massoud

2018-03-01

The effects of rare earth intermetallics and grain refinement by alloying and hot extrusion on the mechanical properties of Mg-Gd-Al-Zn alloys have been studied to elucidate some useful ways to enhance the mechanical properties of magnesium alloys. It was revealed that aluminum as an alloying element is a much better grain refining agent compared with gadolinium, but the simultaneous presence of Al and Gd can refine the as-cast grain size more efficiently. The presence of fine and widely dispersed rare earth intermetallics was found to be favorable to achieve finer recrystallized grains during hot deformation by extrusion. The presence of coarse dendritic structure in the GZ61 alloy, grain boundary eutectic containing Mg17Al12 phase in the AZ61 alloy, and rare earth intermetallics with unfavorable morphology in the Mg-4Gd-2Al-1Zn alloy was found to be detrimental to mechanical properties of the alloy in the as-cast condition. As a result, the microstructural refinement induced by hot extrusion process resulted in a significant enhancement in strength and ductility of the alloys. The presence of intermetallic compounds in the extruded Mg-4Gd-2Al-1Zn and Mg-2Gd-4Al-1Zn alloys deteriorated tensile properties, which was related to the fact that such intermetallic compounds act as stress risers and microvoid initiation sites.

Maternal dietary intakes of refined grains during pregnancy and growth through the first 7 y of life among children born to women with gestational diabetes.

PubMed

Zhu, Yeyi; Olsen, Sjurdur F; Mendola, Pauline; Halldorsson, Thorhallur I; Yeung, Edwina H; Granström, Charlotta; Bjerregaard, Anne A; Wu, Jing; Rawal, Shristi; Chavarro, Jorge E; Hu, Frank B; Zhang, Cuilin

2017-07-01

Background: Refined grains, a major source of dietary carbohydrates, have been related to impaired glucose homeostasis and obesity. Emerging animal data suggest that in utero exposure to dietary refined carbohydrates may predispose offspring to an obese phenotype, indicating a potential role for nutritional programming in the early origins of obesity, but intergenerational human data are lacking. Objective: We prospectively investigated refined-grain intake during pregnancy in association with offspring growth through age 7 y among high-risk children born to women with gestational diabetes mellitus (GDM). Design: The analysis included 918 mother-singleton child dyads from the Danish National Birth Cohort. Offspring body mass index z scores (BMIZs) were calculated by using weight and length or height measured at birth, 5 and 12 mo, and 7 y. Overweight or obesity was defined by WHO cutoffs. Linear and Poisson regressions were used, with adjustment for maternal demographic, lifestyle, and dietary factors. Results: Refined-grain intake during pregnancy was positively associated with offspring BMIZ (adjusted β per serving increase per day: 0.09; 95% CI: 0.02, 0.15) and risk of overweight or obesity at age 7 y [adjusted RR (aRR) comparing the highest with the lowest quartile: 1.80; 95% CI: 1.09, 2.98; P -trend = 0.032]. The association appeared to be more pronounced among children who were breastfed <6 mo. The substitution of 1 serving refined grains/d with an equal serving of whole grains during pregnancy was related to a 10% reduced risk of offspring overweight or obesity at 7 y of age (aRR: 0.90; 95% CI: 0.82, 0.98). No associations were observed between refined-grain intake and infant growth. Conclusions: Higher maternal refined-grain intake during pregnancy was significantly related to a greater BMIZ and a higher risk of overweight or obesity at age 7 y among children born after pregnancies complicated by GDM. The findings highlight pregnancy as a potential window

Intermetallic Growth and Interfacial Properties of the Grain Refiners in Al Alloys.

PubMed

Li, Chunmei; Cheng, Nanpu; Chen, Zhiqian; Xie, Zhongjing; Hui, Liangliang

2018-04-20

Al₃TM(TM = Ti, Zr, Hf, Sc) particles acting as effective grain refiners for Al alloys have been receiving extensive attention these days. In order to judge their nucleation behaviors, first-principles calculations are used to investigate their intermetallic and interfacial properties. Based on energy analysis, Al₃Zr and Al₃Sc are more suitable for use as grain refiners than the other two intermetallic compounds. Interfacial properties show that Al/Al₃TM(TM = Ti, Zr, Hf, Sc) interfaces in I-ter interfacial mode exhibit better interface wetting effects due to larger Griffith rupture work and a smaller interface energy. Among these, Al/Al₃Sc achieves the lowest interfacial energy, which shows that Sc atoms should get priority for occupying interfacial sites. Additionally, Sc-doped Al/Al₃(Zr, Sc) interfacial properties show that Sc can effectively improve the Al/Al₃(Zr, Sc) binding strength with the Al matrix. By combining the characteristics of interfaces with the properties of intermetallics, the core-shell structure with Al₃Zr-core or Al₃Zr(Sc1-1)-core encircled with an Sc-rich shell forms.

Use of whole grain and refined flour from tannin and non-tannin sorghum (Sorghum bicolor (L.) Moench) varieties in frybread.

PubMed

Rose, Devin J; Williams, Emily; Mkandawire, Nyambe L; Weller, Curtis L; Jackson, David S

2014-07-01

Frybreads were prepared using wheat flour and wheat-sorghum composite flours (refined and whole grain; white, tannin-free and red, tannin-containing) at 0, 25, 50, and 75% sorghum flour. Hardness, volume, specific volume, color, and oil uptake were determined. Frybreads made with refined white, tannin-free sorghum were also evaluated in a sensory panel. Substitution of sorghum flour for wheat flour reduced the volume and increased the darkness of the fried dough pieces compared with wheat flour controls. Oil absorption was unaffected when using white, tannin-free sorghum. When using red, tannin-containing sorghum, oil absorption increased for refined flour and decreased for whole grain flour, suggesting that a component only present in the whole grain tannin-containing Sorghum--perhaps tannins themselves--may decrease oil uptake. Panelists rated frybreads containing up to 50% white, tannin-free sorghum flour as not significantly different from control frybreads made with refined wheat flour.

Grain Refinement by Authigenic Inoculation Inherited from the Medium-Range Order Structure of Ni-Cr-W Superalloy

NASA Astrophysics Data System (ADS)

Gao, Zhongtang; Hu, Rui; Guo, Wei; Zhang, Chuanwei

2018-04-01

The combination of liquidus casting and thermal control solidification furnace was applied to obtain a fine-grained ingot. A rapid quenching method and x-ray diffraction measurement were used to investigate the effect of authigenic inoculation on grain refinement. The structure factor S(Q) of liquid Ni-Cr-W superalloy at 1400 °C (Liquidus temperature) and bright-field image of the microstructures quenched from 1400 °C have been measured by the high-temperature x-ray diffractometer and the transmission electron microscopy (TEM), respectively. The results show that a pre-peak exists on a S(Q) curve at the liquidus temperature. The clusters of atom in rapidly quenched microstructures obtained by isothermal heat treatment at 1400 °C were studied using TEM. Meanwhile, the effect of isothermal different temperatures on rapidly quenched microstructures was studied. The results also show that there are only the globular, equiaxed grains distributed in the solidification structure. These particles are inherited from the medium-range order structure, which is beneficial for grain refinement. The normalized work-hardening rate-strain curve indicates the work-hardening rate of fine grain is higher than that of conventional grain at the same temperature and the same deformation.

Grain Refinement by Authigenic Inoculation Inherited from the Medium-Range Order Structure of Ni-Cr-W Superalloy

NASA Astrophysics Data System (ADS)

Gao, Zhongtang; Hu, Rui; Guo, Wei; Zhang, Chuanwei

2018-05-01

The combination of liquidus casting and thermal control solidification furnace was applied to obtain a fine-grained ingot. A rapid quenching method and x-ray diffraction measurement were used to investigate the effect of authigenic inoculation on grain refinement. The structure factor S( Q) of liquid Ni -Cr-W superalloy at 1400 °C (Liquidus temperature) and bright-field image of the microstructures quenched from 1400 °C have been measured by the high-temperature x-ray diffractometer and the transmission electron microscopy (TEM), respectively. The results show that a pre-peak exists on a S( Q) curve at the liquidus temperature. The clusters of atom in rapidly quenched microstructures obtained by isothermal heat treatment at 1400 °C were studied using TEM. Meanwhile, the effect of isothermal different temperatures on rapidly quenched microstructures was studied. The results also show that there are only the globular, equiaxed grains distributed in the solidification structure. These particles are inherited from the medium-range order structure, which is beneficial for grain refinement. The normalized work-hardening rate-strain curve indicates the work-hardening rate of fine grain is higher than that of conventional grain at the same temperature and the same deformation.

Ferrite grain refinement in low carbon Cu–P–Cr–Ni–Mo weathering steel at various temperatures in the (α + γ) region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Chunling, E-mail: zhangchl@ysu.edu.cn; School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401; Zhang, Mengmeng

2016-03-15

Self-designed Cu–P–Cr–Ni–Mo weathering steel was subjected to compression test to determine the mechanism of ferrite grain refinement from 750 °C to 925 °C. Optical microscopic images showed that ferrite grain size declined, whereas the ferrite volume fraction increased with increasing compression temperature. Electron backscatter diffraction patterns revealed that several low-angle boundaries shifted to high-angle boundaries, thereby generating fine ferrite grains surrounded by high-angle boundaries. Numerous low-angle boundaries were observed within ferrite grains at 750 °C, which indicated the existence of pre-eutectoid ferrite. Results showed that ferrite grain refinement could be due to continuous dynamic recrystallization at 750 °C and 775more » °C, and deformation-induced ferrite transformation could be the main mechanism at 800 °C and 850 °C. Fine equiaxed ferrite grains with size ranging from 1.77 μm to 2.69 μm were produced in the (α + γ) dual-phase region. - Graphical abstract: There is a close relationship between the microstructure evolution and flow curves during deformation. Fine equiaxed ferrite grains with size ranging from 1.77 μm to 2.69 μm were achieved in the (α + γ) dual-phase region. Ferrite grain refinement could be due to continuous dynamic recrystallization at 750 °C and 775 °C, and deformation-induced ferrite transformation at 800 °C and 850 °C. The occurrence of deformation-induced ferrite transformation and continuous dynamic recrystallization can be monitored by analysis of flow curves and microstructures. Deformation-induced ferrite transformation leads to the dynamic softening in flow curve when temperature just below A{sub r3}, while the dynamic softening in flow curve is ferrite continuous dynamic recrystallization (Special Fig. 5b). - Highlights: • Compression deformation was operated at temperatures from 750 °C to 925 °C at a strain rate of 0.1 s–1, and a strain of 1.2. • Fine equiaxed ferrite

Intermetallic Growth and Interfacial Properties of the Grain Refiners in Al Alloys

PubMed Central

Li, Chunmei; Cheng, Nanpu; Chen, Zhiqian; Xie, Zhongjing; Hui, Liangliang

2018-01-01

Al3TM(TM = Ti, Zr, Hf, Sc) particles acting as effective grain refiners for Al alloys have been receiving extensive attention these days. In order to judge their nucleation behaviors, first-principles calculations are used to investigate their intermetallic and interfacial properties. Based on energy analysis, Al3Zr and Al3Sc are more suitable for use as grain refiners than the other two intermetallic compounds. Interfacial properties show that Al/Al3TM(TM = Ti, Zr, Hf, Sc) interfaces in I-ter interfacial mode exhibit better interface wetting effects due to larger Griffith rupture work and a smaller interface energy. Among these, Al/Al3Sc achieves the lowest interfacial energy, which shows that Sc atoms should get priority for occupying interfacial sites. Additionally, Sc-doped Al/Al3(Zr, Sc) interfacial properties show that Sc can effectively improve the Al/Al3(Zr, Sc) binding strength with the Al matrix. By combining the characteristics of interfaces with the properties of intermetallics, the core-shell structure with Al3Zr-core or Al3Zr(Sc1-1)-core encircled with an Sc-rich shell forms. PMID:29677155

Dual mechanisms of grain refinement in a FeCoCrNi high-entropy alloy processed by high-pressure torsion

PubMed Central

Wu, Wenqian; Song, Min; Ni, Song; Wang, Jingshi; Liu, Yong; Liu, Bin; Liao, Xiaozhou

2017-01-01

An equiatomic FeCoCrNi high-entropy alloy with a face-centered cubic structure was fabricated by a powder metallurgy route, and then processed by high-pressure torsion. Detailed microscopy investigations revealed that grain refinement from coarse grains to nanocrystalline grains occurred mainly via concurrent nanoband (NB) subdivision and deformation twinning. NB–NB, twin–NB and twin–twin interactions contributed to the deformation process. The twin–twin interactions resulted in severe lattice distortion and accumulation of high densities of dislocations in the interaction areas. With increasing strain, NB subdivision and interactions between primary twins and inclined secondary stacking faults (SFs)/nanotwins occurred. Secondary nanotwins divided the primary twins into many equiaxed parts, leading to further grain refinement. The interactions between secondary SFs/nanotwins associated with the presence of Shockley partials and primary twins also transformed the primary twin boundaries into incoherent high-angle grain boundaries. PMID:28429759

Grain Refinement Kinetics in a Low Alloyed Cu–Cr–Zr Alloy Subjected to Large Strain Deformation

PubMed Central

Morozova, Anna; Borodin, Elijah; Bratov, Vladimir; Zherebtsov, Sergey; Kaibyshev, Rustam

2017-01-01

This paper investigates the microstructural evolution and grain refinement kinetics of a solution-treated Cu–0.1Cr–0.06Zr alloy during equal channel angular pressing (ECAP) at a temperature of 673 K via route BC. The microstructural change during plastic deformation was accompanied by the formation of the microband and an increase in the misorientations of strain-induced subboundaries. We argue that continuous dynamic recrystallization refined the initially coarse grains, and discuss the dynamic recrystallization kinetics in terms of grain/subgrain boundary triple junction evolution. A modified Johnson–Mehl–Avrami–Kolmogorov relationship with a strain exponent of about 1.49 is used to express the strain dependence of the triple junctions of high-angle boundaries. Severe plastic deformation by ECAP led to substantial strengthening of the Cu–0.1Cr–0.06Zr alloy. The yield strength increased from 60 MPa in the initial state to 445 MPa after a total strain level of 12. PMID:29210990

Grain Refinement and Texture Mitigation in Low Boron Containing TiAl-Alloys

NASA Astrophysics Data System (ADS)

Hecht, Ulrike; Witusiewicz, Victor T.

2017-12-01

Controlling the grain size and texture of lamellar TiAl-alloys is essential for well-balanced creep and fatigue properties. Excellent refinement and texture mitigation are achieved in aluminum lean alloys by low boron additions of 0.2 at.%. This amount is sufficient to promote in situ formation of ultrafine borides during the last stages of body centered cubic (BCC) solidification. The borides subsequently serve as nucleation sites for hexagonal close packed (HCP) during the BCC-HCP phase transformation. Bridgman solidification experiments with alloy Ti-43Al-8Nb-0.2C-0.2B were performed under a different growth velocity, i.e., cooling rate, to evaluate the HCP grain size distribution and texture. For slow-to-moderate cooling rates, about 65% of HCP grains are randomly oriented, despite the pronounced texture of the parent BCC phase resulting from directional solidification. For high cooling rates, obtained by quenching, texture mitigation is less pronounced. Only 28% of the HCP grains are randomly oriented, the majority being crystallographic variants of the Burgers orientation relationship.

Mechanisms of grain refinement in aluminum alloys in the process of severe plastic deformation

NASA Astrophysics Data System (ADS)

Kaibyshev, R. O.; Mazurina, I. A.; Gromov, D. A.

2006-01-01

A study of the mechanisms of grain refinement in the process of severe plastic deformation of two aluminum alloys, i.e., 2219 bearing nanometric particles of Al3Zr and low-alloy Al-3% Cu, is described. The alloys are deformed by the method of equal channel angular pressing at 250°C to a maximum strain degree of about 12. The angles of (sub)grain boundaries in alloy 2219 are determined with the help of transmission electron microscopy by the method of Kikuchi lines. The evolution of the microstructure in alloy Al-3% Cu is studied with the help of grain-boundary maps obtained by the method of electron back-scattered diffraction.

Grain Refinement Efficiency in Commercial-Purity Aluminum Influenced by the Addition of Al-4Ti Master Alloys with Varying TiAl₃ Particles.

PubMed

Zhao, Jianhua; He, Jiansheng; Tang, Qi; Wang, Tao; Chen, Jing

2016-10-26

A series of Al-4Ti master alloys with various TiAl₃ particles were prepared via pouring the pure aluminum added with K₂TiF₆ or sponge titanium into three different molds made of graphite, copper, and sand. The microstructure and morphology of TiAl₃ particles were characterized and analyzed by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The microstructure of TiAl₃ particles in Al-4Ti master alloys and their grain refinement efficiency in commercial-purity aluminum were investigated in this study. Results show that there were three different morphologies of TiAl₃ particles in Al-4Ti master alloys: petal-like structures, blocky structures, and flaky structures. The Al-4Ti master alloy with blocky TiAl₃ particles had better and more stable grain refinement efficiency than the master alloys with petal-like and flaky TiAl₃ particles. The average grain size of the refined commercial-purity aluminum always hereditarily followed the size of the original TiAl₃ particles. In addition, the grain refinement efficiency of Al-4Ti master alloys with the same morphology, size, and distribution of TiAl₃ particles prepared through different processes was almost identical.

Grain refinement of 7075Al alloy microstructures by inoculation with Al-Ti-B master alloy

NASA Astrophysics Data System (ADS)

Hotea, V.; Juhasz, J.; Cadar, F.

2017-05-01

This paper aims to bring some clarification on grain refinement and modification of high strength alloys used in aerospace technique. In this work it was taken into account 7075 Al alloy, and the melt treatment was carried out by placing in the form of master alloy wire ternary AlTiB the casting trough at 730°C. The morphology of the resulting microstructures was characterized by optical microscopy. Micrographs unfinished and finished with pre-alloy containing ternary Al5Ti1B evidence fine crystals, crystal containing no columnar structure and highlights the size of the dendrites, and intermetallic phases occurring at grain boundaries in Al-Zn-Mg-Cu alloy. It has been found that these intermetallic compounds are MgZn2 type. AlTiB master alloys finishing ensures a fine eutectic structure, which determines the properties of hardware and improving the mechanical properties of aluminum alloys used in aeronautical engineering.

Distribution of trace elements in a modified and grain refined aluminium-silicon hypoeutectic alloy.

PubMed

Faraji, M; Katgerman, L

2010-08-01

The influence of modifier and grain refiner on the nucleation process of a commercial hypoeutectic Al-Si foundry alloy (A356) was investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis technique (EPMA). Filtering was used to improve the casting quality; however, it compromised the modification of silicon. Effect of filtering on strontium loss was also studied using the afore-mentioned techniques. EPMA was used to trace the modifying and grain refining agents inside matrix and eutectic Si. This was to help understanding mechanisms of nucleation and modification in this alloy. Using EPMA, the negative interaction of Sr and Al3TiB was closely examined. In modified structure, it was found that the maximum point of Sr concentration was in line with peak of silicon; however, in case of just 0.1wt% added Ti, the peak of Ti concentration was not in line with aluminium, (but it was close to Si peak). Furthermore, EPMA results showed that using filter during casting process lowered the strontium content, although produced a cleaner melt. (c) 2010 Elsevier Ltd. All rights reserved.

Consumption of red and processed meat and refined grains for 4weeks decreases insulin sensitivity in insulin-resistant adults: A randomized crossover study.

PubMed

Kim, Yoona; Keogh, Jennifer B; Clifton, Peter M

2017-03-01

Red and processed meat and refined grains are associated with an increased risk of type 2 diabetes. Interventions are limited. We hypothesized that a diet high in red and processed meat and refined grains (HMD) would decrease insulin sensitivity compared to a diet high in whole grains, nuts, dairy and legumes with no red meat (HWD). Forty-nine subjects without diabetes [15 men and 34 women, age, 35.6±15.7 years, body mass index (BMI), 27±5.9kg/m 2 ] underwent two 4-week weight-stable dietary interventions in a randomized crossover design. The insulin sensitivity index (ISI) was calculated from the last 30min of a continuous low-dose insulin (25mU/kg·h) and glucose (4mg/kg·min) infusion test (LDIGIT 120-150min ) at the end of each diet. The population fell into two very discrete groups: those with a very low insulin response in the LDIGIT 120-150min on HMD (Group 1<56pmol/L, n=24), and those with relatively normal insulin responses (Group 2>56pmol/L, n=25). Group 2 had significantly higher insulin concentrations [(median and interquartile range) 153, 180 for HMD vs. 123, 149pmol/L for HWD; P=0.019] and glucose concentrations [(mean±standard deviation) 7.4±1.3 for HMD vs.6.7±1.2mmol/L for HWD; P=0.05], resulting in a significantly decreased ISI [(median and interquartile range) 21.1, 34.2 for HMD vs. 31.6, 39.4 for HWD; P=0.014] compared to HWD. Log ISI after HMD was significantly correlated with BMI (r=-0.5; P=0.009), fat mass (r=-0.55; P=0.004) and self-reported activity levels (r=-0.45; P=0.024). A dietary pattern high in red and processed meat and refined grains decreased insulin sensitivity compared to a dietary pattern high in whole grains, nuts, dairy products and legumes only in relatively insulin-resistant adults. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of corrosion behavior between coarse grained and nano/ultrafine grained alloy 690

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Ting, Guo

2016-01-01

The effect of grain refinement on corrosion resistance of alloy 690 was investigated. The electron work function value of coarse grained alloy 690 was higher than that of nano/ultrafine grained one. The grain refinement reduced the electron work function of alloy 690. The passive films formed on coarse grained and nano/ultrafine grained alloy 690 in borate buffer solution were studied by potentiodynamic curves and electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the grain refinement improved corrosion resistance of alloy 690. This was attributed to the fact that grain refinement promoted the enrichment of Cr2O3 and inhibited Cr(OH)3 in the passive film. More Cr2O3 in passive film could significantly improve the corrosion resistance of the nano/ultrafine grained alloy 690.

No Evidence of Increased Risk of Stroke with Consumption of Refined Grains: A Meta-analysis of Prospective Cohort Studies.

PubMed

Wu, Demo; Guan, Yixiang; Lv, Shujun; Wang, Haibo; Li, Jun

2015-12-01

Results of the relationships between dietary consumption of refined grains and the risk of stroke are mixed. This study was based on a meta-analysis of prospective cohort studies. We systematically searched the MEDLINE (from January 1, 1966) and EMBASE (from January 1, 1974) databases up to November 30, 2014. Random-effects models were used to calculate summary relative risks (SRRs) and 95% confidence intervals (CIs). Between-study heterogeneity was assessed using Cochran's Q and I(2) statistics. Eight prospective studies (7 publications) with a total of 410,821 subjects and 8284 stroke events were included in the meta-analysis. Overall, a diet containing greater amounts of refined grains was not associated with risk of stroke, with no evidence of heterogeneity among studies (SRR = 1.02; 95% CI, .93-1.10; P(heterogeneity) = .970; I(2) = 0). In addition, no significant associations between consumption of refined grains and risk of stroke were found for both women and men, for both hemorrhagic and ischemic strokes, and for both incident and fatal strokes. These null results are consistent with those of linear dose-response meta-analyses (SRR = .98; 95% CI, .73-1.03 for per 3 servings/day). Consumption of white rice was not associated with risk of stroke (SRR = 1.01; 95% CI, .93-1.11; P(heterogeneity) = .966; I(2) = 0). The current meta-analysis provides some evidence for the hypothesis that consumption of refined grains was not associated with risk of stroke and its subtypes. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Grain Refinement Efficiency in Commercial-Purity Aluminum Influenced by the Addition of Al-4Ti Master Alloys with Varying TiAl3 Particles

PubMed Central

Zhao, Jianhua; He, Jiansheng; Tang, Qi; Wang, Tao; Chen, Jing

2016-01-01

A series of Al-4Ti master alloys with various TiAl3 particles were prepared via pouring the pure aluminum added with K2TiF6 or sponge titanium into three different molds made of graphite, copper, and sand. The microstructure and morphology of TiAl3 particles were characterized and analyzed by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The microstructure of TiAl3 particles in Al-4Ti master alloys and their grain refinement efficiency in commercial-purity aluminum were investigated in this study. Results show that there were three different morphologies of TiAl3 particles in Al-4Ti master alloys: petal-like structures, blocky structures, and flaky structures. The Al-4Ti master alloy with blocky TiAl3 particles had better and more stable grain refinement efficiency than the master alloys with petal-like and flaky TiAl3 particles. The average grain size of the refined commercial-purity aluminum always hereditarily followed the size of the original TiAl3 particles. In addition, the grain refinement efficiency of Al-4Ti master alloys with the same morphology, size, and distribution of TiAl3 particles prepared through different processes was almost identical. PMID:28773987

Coarse Grained Model for Biological Simulations: Recent Refinements and Validation

PubMed Central

Vicatos, Spyridon; Rychkova, Anna; Mukherjee, Shayantani; Warshel, Arieh

2014-01-01

Exploring the free energy landscape of proteins and modeling the corresponding functional aspects presents a major challenge for computer simulation approaches. This challenge is due to the complexity of the landscape and the enormous computer time needed for converging simulations. The use of various simplified coarse grained (CG) models offers an effective way of sampling the landscape, but most current models are not expected to give a reliable description of protein stability and functional aspects. The main problem is associated with insufficient focus on the electrostatic features of the model. In this respect our recent CG model offers significant advantage as it has been refined while focusing on its electrostatic free energy. Here we review the current state of our model, describing recent refinement, extensions and validation studies while focusing on demonstrating key applications. These include studies of protein stability, extending the model to include membranes and electrolytes and electrodes as well as studies of voltage activated proteins, protein insertion trough the translocon, the action of molecular motors and even the coupling of the stalled ribosome and the translocon. Our example illustrates the general potential of our approach in overcoming major challenges in studies of structure function correlation in proteins and large macromolecular complexes. PMID:25050439

Grain Refinement of Al-Si-Fe-Cu-Zn-Mn Based Alloy by Al-Ti-B Alloy and Its Effect on Mechanical Properties.

PubMed

Yoo, Hyo-Sang; Kim, Yong-Ho; Jung, Chang-Gi; Lee, Sang-Chan; Lee, Seong-Hee; Son, Hyeon-Taek

2018-03-01

We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

REFMAC5 for the refinement of macromolecular crystal structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murshudov, Garib N., E-mail: garib@ysbl.york.ac.uk; Skubák, Pavol; Lebedev, Andrey A.

The general principles behind the macromolecular crystal structure refinement program REFMAC5 are described. This paper describes various components of the macromolecular crystallographic refinement program REFMAC5, which is distributed as part of the CCP4 suite. REFMAC5 utilizes different likelihood functions depending on the diffraction data employed (amplitudes or intensities), the presence of twinning and the availability of SAD/SIRAS experimental diffraction data. To ensure chemical and structural integrity of the refined model, REFMAC5 offers several classes of restraints and choices of model parameterization. Reliable models at resolutions at least as low as 4 Å can be achieved thanks to low-resolution refinement toolsmore » such as secondary-structure restraints, restraints to known homologous structures, automatic global and local NCS restraints, ‘jelly-body’ restraints and the use of novel long-range restraints on atomic displacement parameters (ADPs) based on the Kullback–Leibler divergence. REFMAC5 additionally offers TLS parameterization and, when high-resolution data are available, fast refinement of anisotropic ADPs. Refinement in the presence of twinning is performed in a fully automated fashion. REFMAC5 is a flexible and highly optimized refinement package that is ideally suited for refinement across the entire resolution spectrum encountered in macromolecular crystallography.« less

Nucleation and Grain Refinement of 7A04 Aluminum Alloy Under a Low-Power Electromagnetic Pulse

NASA Astrophysics Data System (ADS)

Bai, Qingwei; Ma, Yonglin; Xing, Shuqing; Bao, Xinyu; Feng, Yanfei; Kang, Xiaolan

2018-02-01

The effects of a low-power electromagnetic pulse on the grain size and cooling curve of high-strength aluminum alloy 7A04 were investigated for various pulse duty cycles. This electromagnetic pulse treatment was found to effectively produce fine grains with globular crystals and a uniform microstructure for pulse duty cycles between 20 and 40%. The key factors that affected grain refinement under the electromagnetic pulse included the electromagnetic energy and the conversion frequency between \\varvec{B} and \\varvec{E} . The nucleation rate increased as the nucleation period was extended. A new kinetic condition of magnetic nucleation was explored by decreasing the critical Gibbs free energy in the electromagnetic pulse, which was more sensitive under low undercooling. In addition, the crystal orientation was controlled in such a solidification environment.

Equal Channel Angular Pressing (ECAP) and Its Application to Grain Refinement of Al-Zn-Mg-Cu Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tekeli, Sueleyman; Gueral, Ahmet

Microstructure of a metal can be considerably changed by severe plastic deformation techniques such as high pressure torsion, extrusion and equal-channel angular pressing (ECAP). Among these methods, ECAP is particularly attractive because it has a potential for introducing significant grain refinement and homogeneous microstructure into bulk materials. Typically, it reduces the grain size to the submicrometer level or even nanometer range and thus produces materials that are capable of exhibiting unusual mechanical properties. In the present study, a test unites for equal channel angular pressing was constructed and this system was used for Al-Zn-Mg-Cu alloy. After the optimization tests, itmore » was seen that the most effective lubricant for the dies was MoS{sub 2}, the pressing pressure was around 25-35 ton and the pressing speed was 2 mm/s. By using these parameters, the Al-Zn-Mg-Cu alloy was successfully ECAPed up to 14 passes at 200 deg. C using route C. After ECAP tests, the specimens were characterized by transmission electron microscope (TEM), hardness and macrostructural investigations. It was seen that the plastic deformation in the ECAPed specimens occurred from edge to the centre like whirlpool. In addition, the deformation intensity increased with increasing pass number. The grain size of the specimens effectively also decreased with increasing pass number. That is, while the grain size of unECAPed specimen was 10 {mu}m, this value decreased to 300 nm after 14 passes. At the beginning, while there was a banding tendency in the grains toward deformation direction, homogeneous and equiaxed grains were formed with increasing pass number. This grain refinement was as a result of an interaction between shear strain and thermal recovery during ECAP processing. Hardness measurements showed that the hardness values increased up to 4 passes, decreased effectively at 6th pass, again increased at 8th pass and after this pass, the hardness again decreased due

Grain Refinement and Improvement of Solidification Defects in Direct-Chill Cast Billets of A4032 Alloy by Melt Conditioning

NASA Astrophysics Data System (ADS)

Li, Hu-Tian; Zhao, Pizhi; Yang, Rongdong; Patel, Jayesh B.; Chen, Xiangfu; Fan, Zhongyun

2017-10-01

Melt-conditioned, direct-chill (MC-DC) casting is an emerging technology to manipulate the solidification process by melt conditioning via intensive shearing in the sump during DC casting to tailor the solidification microstructure and defect formation. When using MC-DC casting technology in an industrial scale DC cast billet of an A4032 aluminum alloy, significant grain refinement and uniform microstructure can be achieved in the primary α-Al phase with fine secondary dendritic arm spacing (SDAS). Improved macrosegregation is quantitatively characterized and correlated with the suppression of channel segregation. The mechanisms for the prevention of channel segregation are attributed to the increased local cooling rate in the liquid-solid phase region in the sump and the formation of fine equiaxed dendritic grains under intensive melt shearing during MC-DC casting. A critical cooling rate has been identified to be around 0.5 to 1 K/s (°C/s) for the channel segregation to happen in the investigated alloy based on quantitative metallographic results of SDAS. Reduction and refinement of microporosity is attributed to the improved permeability in the liquid-solid phase region estimated by the Kozeny-Carman relationship. The potential improvement in the mechanical properties achievable in MC-DC cast billets is indicated by the finer and more uniform forging streamline in the forgings of MC-DC cast billet.

Differentiation of whole grain and refined wheat (T. aestivum) flour using a fuzzy mass spectrometric fingerprinting and chemometric approaches

USDA-ARS?s Scientific Manuscript database

A fuzzy mass spectrometric (MS) fingerprinting method combined with chemometric analysis was established to provide rapid discrimination between whole grain and refined wheat flour. Twenty one samples, including thirteen samples from three cultivars and eight from local grocery store, were studied....

The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints.

PubMed

Al-Ezzi, Salih; Quan, Gaofeng; Elrayah, Adil

2018-05-07

This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties.

The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints

PubMed Central

Quan, Gaofeng

2018-01-01

This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties. PMID:29735894

Reformulation of pizza crust in restaurants may increase whole-grain intake among children.

PubMed

Tritt, Aimee; Reicks, Marla; Marquart, Len

2015-06-01

Whole-grain intake among children is well below recommendations. The purpose of the present study was to test the acceptability and liking of pizza made with whole-grain crust compared with refined-grain crust among children in restaurant and school settings. Plate waste data were collected via observation from child restaurant patrons consuming pizza made with either whole-grain or refined-grain crust. Waste was estimated by trained observers over eight months (August 2012-March 2013). Percentage waste was calculated and compared by crust type. A taste test was conducted with school children who tasted pizza made with whole-grain crust alongside pizza made with refined-grain crust and rated their liking of each product. Liking ratings were compared by crust type. Five Green Mill restaurant (a Midwest US chain) locations and one elementary school in the Minneapolis/St. Paul metropolitan area, Minnesota, USA. Child restaurant patrons (n 394) and school children (n 120, grades 3-5). Children consumed as much of the pizza made with whole-grain crust (42·1 %) as the pizza made with refined-grain crust (44·6 %; P=0·55), based on an average serving size of 350-400 g. Liking ratings for both types of pizza were high (>4·5 of 5) and did not differ by crust type (P=0·47). These positive consumption and liking outcomes indicate that whole-grain pizza crust is well accepted among children in a restaurant setting. The impact on whole-grain intake could be substantial if large, national restaurant chains served pizza made with whole-grain crust.

Associations of whole and refined grain intakes with adiposity-related cancer risk in the Framingham Offspring Cohort (1991-2013)

USDA-ARS?s Scientific Manuscript database

Objective: The objective of this prospective cohort study is to evaluate associations between whole and refined grains and their food sources in relation to risk of adiposity-related cancers combined and three of the most commonly diagnosed site-specific cancers in the US: breast, prostate, and colo...

Grain refinement to improve impact toughness in 9Cr-1Mo steel through a double austenitization treatment

NASA Astrophysics Data System (ADS)

Karthikeyan, T.; Thomas Paul, V.; Saroja, S.; Moitra, A.; Sasikala, G.; Vijayalakshmi, M.

2011-12-01

This paper presents the results of an experimental investigation where an enhancement in Charpy impact toughness and decrease in DBTT was obtained through grain refinement in 9Cr-1Mo steel. The steel in the normalized and tempered condition (1323 K/air cool + 1023 K/2 h/air cool) had an average prior-austenite grain size of 26 μm. By designing a two-stage normalizing (1323 K/2 h/water quench + 1223 K/2 h/air cool) and tempering treatment (1023 K/2 h/air cool), a homogeneous tempered martensite microstructure with a lesser prior-austenite grain size of 12 μm could be obtained. An improvement trend in impact properties of standard sized Charpy specimens was obtained in fine-grained steel: upper shelf energy increased from 175 J to 210 J, and DBTT reduced from 243 K to 228 K. This heat treatment is unique since an attempt to carry out a single-stage low temperature normalizing treatment (1223 K/2 h/air cool) did not give a complete martensite structure, due to the incomplete dissolution of carbides during austenitization.

Effects of Annular Electromagnetic Stirring Coupled with Intercooling on Grain Refinement and Homogeneity During Direct Chill Casting of Large-Sized 7005 Alloy Billet

NASA Astrophysics Data System (ADS)

Luo, Yajun; Zhang, Zhifeng; Li, Bao; Gao, Mingwei; Qiu, Yang; He, Min

2017-12-01

To obtain a large-sized, high-quality aluminum alloy billet, an advanced uniform direct chill (UDC) casting method was developed by combining annular electromagnetic stirring (A-EMS) with intercooling in the sump. The 7005 alloy was chosen to investigate the effect of UDC on grain refinement and homogeneity during normal direct chill (NDC) casting. It was concluded that the microstructure consisting of both primary α-Al phase and secondary phases becomes finer and more homogeneous for the billets prepared with UDC casting compared to those prepared with NDC casting, and the forced cooling from both the inner and outer melt under A-EMS has a measurable effect on grain refinement and homogeneity.

Grain refinement control in TIG arc welding

NASA Technical Reports Server (NTRS)

Iceland, W. F.; Whiffen, E. L. (Inventor)

1975-01-01

A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed. In the method the frequency of dc welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored. At some frequency in the preselected range the arc gas voltage will pass through a maximum. By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced.

Whole- and refined-grain intakes are differentially associated with abdominal visceral and subcutaneous adiposity in healthy adults: The Framingham Heart Study

USDA-ARS?s Scientific Manuscript database

Different aspects of diet may be differentially related to body fat distribution. The purpose of this study was to assess associations between whole- and refined- grain intake and abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). We examined the cross-sectional associati...

Nano-Sized Grain Refinement Using Friction Stir Processing

DTIC Science & Technology

2013-03-01

friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir ... Friction Stir Processing, Magnesium, Nano-size grains Abstract A key characteristic of a friction stir weld is a very fine grain microstructure...state process developed on the basis of the friction stir welding (FSW) technique invented by The Welding Institute (TWI) in 1991 [2]. During

Refining The Grain: Using Resident-Based Walkability Audits To Better Understand Walkable Urban Form.

PubMed

Schlossberg, Marc; Johnson-Shelton, Deb; Evers, Cody; Moreno, Geraldine

Researchers use measures of street connectivity to assess neighborhood walkability and many studies show a relationship between neighborhood design and walking activity. Yet, the core of those connectivity measures are based on constructs designed for analyzing automobile mobility - the street network - not pedestrian movement. This paper examines the effect of a finer grained characterization of street connectivity and illustrates the idea using parent ratings of street and intersection walkability for children throughout a suburban school district in Oregon. Several policy and practice recommendations are presented, including a discussion that extends Michael Southworth's (1993; 2005) foundational representation of streets and the walkable city using a refined, more pedestrian-centered approach to visualizing connectivity and walkable urban form.

Effect of whole grains on insulin sensitivity in overweight hyperinsulinemic adults.

PubMed

Pereira, Mark A; Jacobs, David R; Pins, Joel J; Raatz, Susan K; Gross, Myron D; Slavin, Joanne L; Seaquist, Elizabeth R

2002-05-01

Epidemiologic studies have found whole-grain intake to be inversely associated with the risk of type 2 diabetes and heart disease. We tested the hypothesis that whole-grain consumption improves insulin sensitivity in overweight and obese adults. This controlled experiment compared insulin sensitivity between diets (55% carbohydrate, 30% fat) including 6-10 servings/d of breakfast cereal, bread, rice, pasta, muffins, cookies, and snacks of either whole or refined grains. Total energy needs were estimated to maintain body weight. Eleven overweight or obese [body mass index (in kg/m(2)): 27-36] hyperinsulinemic adults aged 25-56 y participated in a randomized crossover design. At the end of each 6-wk diet period, the subjects consumed 355 mL (12 oz) of a liquid mixed meal, and blood samples were taken over 2 h. The next day a euglycemic hyperinsulinemic clamp test was administered. Fasting insulin was 10% lower during consumption of the whole-grain than during consumption of the refined-grain diet (mean difference: -15 +/- 5.5 pmol/L; P = 0.03). After the whole-grain diet, the area under the 2-h insulin curve tended to be lower (-8832 pmol.min/L; 95% CI: -18720, 1062) than after the refined-grain diet. The rate of glucose infusion during the final 30 min of the clamp test was higher after the whole-grain diet (0.07 x 10(-4) mmol.kg(-1).min(-1) per pmol/L; 95% CI: 0.003 x 10(-4), 0.144 x 10(-4)). Insulin sensitivity may be an important mechanism whereby whole-grain foods reduce the risk of type 2 diabetes and heart disease.

Grain Refinement and Mechanical Properties of Cu–Cr–Zr Alloys with Different Nano-Sized TiCp Addition

PubMed Central

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-01-01

The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively. PMID:28786937

Zinc alloy enhances strength and creep resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Machler, M.

1996-10-01

A family of high-performance ternary zinc-copper-aluminum alloys has been developed that provides higher strength, hardness, and creep resistance than the traditional zinc-aluminum alloys Zamak 3, Zamak 5, and ZA-8. Designated ACuZinc, mechanical properties comparable to those of more expensive materials make it suitable for high-load applications and those at elevated temperatures. This article describes the alloy`s composition, properties, and historical development.

Weighing in on whole grains: A review of evidence linking whole grains to body weight

USDA-ARS?s Scientific Manuscript database

U.S. dietary guidelines support the consumption of whole grains in lieu of refined grains. On January 31, 2011, the 2010 Dietary Guidelines for Americans (DGA) were released and the recommendations with respect to grains were for individuals to “Consume at least half of all grains as whole grains” a...

Consumption of whole grains and legumes modulates the genetic effect of the APOA5 -1131C variant on changes in triglyceride and apolipoprotein A-V concentrations in patients with impaired fasting glucose or newly diagnosed type 2 diabetes

PubMed Central

2014-01-01

Background The apolipoprotein A5 gene (APOA5) -1131 T > C polymorphism is associated with mild hypertriglyceridemia in type 2 diabetic subjects, and interacts with dietary fat in the determination of triglyceride concentrations. We examined whether a substitution of whole grains and legumes for refined rice in a high carbohydrate diet (about 65% of energy derived from carbohydrate) may modify the effect of this variant on changes in apolipoprotein A-V (apoA-V) and triglyceride concentrations. Methods We genotyped the APOA5 -1131 T > C in individuals with impaired fasting glucose (IFG) or newly diagnosed type 2 diabetes, who were randomly assigned to either a group ingesting whole grain and legume meals daily or a control group for 12 weeks. Results After dietary intervention, we observed significant interactions between the APOA5 -1131 T > C polymorphism and carbohydrate sources (whole grains and legumes versus refined rice) in the determination of mean percent changes in triglyceride and apoA-V (P interactions <0.001 and =0.038, respectively). In the refined rice group (n = 93), the carriers of the risk C allele (n = 50) showed a greater increase in the mean percent changes of triglyceride and apoA-V than noncarriers after adjusting for HOMA-IR (P = 0.004 and 0.021, respectively). The whole grain and legume group (n = 92), however, showed a decrease in fasting glucose, HOMA-IR, and triglyceride, and an increase in apoA-V, irrespective of genotype. Conclusions The data showed that the magnitude of the genetic effect of the APOA5 -1131C variant on triglyceride and apoA-V levels was modulated when substituting consumption of whole grains and legumes for refined rice as a carbohydrate source in IFG or diabetic subjects. Trial registration ClinicalTrials.gov: NCT01784952. PMID:24690159

Consumption of whole grains and legumes modulates the genetic effect of the APOA5 -1131C variant on changes in triglyceride and apolipoprotein A-V concentrations in patients with impaired fasting glucose or newly diagnosed type 2 diabetes.

PubMed

Kang, Ryungwoo; Kim, Minjoo; Chae, Jey Sook; Lee, Sang-Hyun; Lee, Jong Ho

2014-04-01

The apolipoprotein A5 gene (APOA5) -1131 T > C polymorphism is associated with mild hypertriglyceridemia in type 2 diabetic subjects, and interacts with dietary fat in the determination of triglyceride concentrations. We examined whether a substitution of whole grains and legumes for refined rice in a high carbohydrate diet (about 65% of energy derived from carbohydrate) may modify the effect of this variant on changes in apolipoprotein A-V (apoA-V) and triglyceride concentrations. We genotyped the APOA5 -1131 T > C in individuals with impaired fasting glucose (IFG) or newly diagnosed type 2 diabetes, who were randomly assigned to either a group ingesting whole grain and legume meals daily or a control group for 12 weeks. After dietary intervention, we observed significant interactions between the APOA5 -1131 T > C polymorphism and carbohydrate sources (whole grains and legumes versus refined rice) in the determination of mean percent changes in triglyceride and apoA-V (P interactions <0.001 and =0.038, respectively). In the refined rice group (n = 93), the carriers of the risk C allele (n = 50) showed a greater increase in the mean percent changes of triglyceride and apoA-V than noncarriers after adjusting for HOMA-IR (P = 0.004 and 0.021, respectively). The whole grain and legume group (n = 92), however, showed a decrease in fasting glucose, HOMA-IR, and triglyceride, and an increase in apoA-V, irrespective of genotype. The data showed that the magnitude of the genetic effect of the APOA5 -1131C variant on triglyceride and apoA-V levels was modulated when substituting consumption of whole grains and legumes for refined rice as a carbohydrate source in IFG or diabetic subjects. ClinicalTrials.gov: NCT01784952.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

PubMed

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

The Grain Structure of Castings: Some Aspects of Modelling

NASA Technical Reports Server (NTRS)

Hellawell, A.

1995-01-01

The efficacy of the modelling of the solidification of castings is typically tested against observed cooling curves and the final grain structures and sizes. Without thermo solutal convection, equiaxed grain formation is promoted by introduction of heterogeneous substrates into the melt, as grain refiners. With efficient thermo solutal convection, dendrite fragments from the mushy zone can act as an intrinsic source of equiaxed grains and resort to grain refining additions is unnecessary. The mechanisms of dendrite fragmentation and transport of these fragments are briefly considered.

Strengthening and Improving Yield Asymmetry of Magnesium Alloys by Second Phase Particle Refinement Under the Guidance of Integrated Computational Materials Engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dongsheng; Lavender, Curt

2015-05-08

Improving yield strength and asymmetry is critical to expand applications of magnesium alloys in industry for higher fuel efficiency and lower CO 2 production. Grain refinement is an efficient method for strengthening low symmetry magnesium alloys, achievable by precipitate refinement. This study provides guidance on how precipitate engineering will improve mechanical properties through grain refinement. Precipitate refinement for improving yield strengths and asymmetry is simulated quantitatively by coupling a stochastic second phase grain refinement model and a modified polycrystalline crystal viscoplasticity φ-model. Using the stochastic second phase grain refinement model, grain size is quantitatively determined from the precipitate size andmore » volume fraction. Yield strengths, yield asymmetry, and deformation behavior are calculated from the modified φ-model. If the precipitate shape and size remain constant, grain size decreases with increasing precipitate volume fraction. If the precipitate volume fraction is kept constant, grain size decreases with decreasing precipitate size during precipitate refinement. Yield strengths increase and asymmetry approves to one with decreasing grain size, contributed by increasing precipitate volume fraction or decreasing precipitate size.« less

Solidification Based Grain Refinement in Steels

DTIC Science & Technology

2010-07-20

methods which worked in the SVSU foundry. However, additions of NbO powder, FeTi, misch metal , and rare earth silicide were successful. Misch metal ...and rare earth silicide additions at the ladle are the most promising from an industrial stand point. The project group has begun preparing for the... metal and rare earth silicide additions have also reduced grain size and improved hardness. Instructions: You may use this MS Word file to submit the

Ancient grains and pseudocereals: chemical compositions, nutritional benefits, and roles in 21st century diets

USDA-ARS?s Scientific Manuscript database

In recent history, refined grains have replaced whole grains in the human diet. However, refined grains have fewer phytochemicals and more starches than whole grain. In addition, studies have shown that inclusion of whole grains in a daily diet results in decreased risk of cancer and cardiovascular ...

Incremental Feeding High-Pressure Sliding for Grain Refinement of Large-Scale Sheets: Application to Inconel 718

NASA Astrophysics Data System (ADS)

Takizawa, Yoichi; Sumikawa, Kosei; Watanabe, Kyohei; Masuda, Takahiro; Yumoto, Manabu; Kanai, Yuta; Otagiri, Yoshiharu; Horita, Zenji

2018-03-01

This study updates a process of high-pressure sliding (HPS) recently developed as a severe plastic deformation process under high pressure for grain refinement of sheet samples. The updated version, which we call the incremental feeding HPS (IF-HPS), consists of sliding for SPD and feeding for upsizing the SPD-processed area so that, without increasing the capacity of processing facility, it is possible to cover a much larger area with an SPD-processed ultrafine-grained structure with a grain size of 120 nm. For the IF-HPS processing, anvils with flat surfaces but without grooves are used in an unconstrained condition, and the feeding distance is set equal to the deformed width. A Ni-based superalloy (Inconel 718) is processed by the IF-HPS under 4 GPa at room temperature, and it is possible to obtain an SPD-processed sheet with dimensions of approximately 100 × 100 × 1 mm3. Strain distribution and evolution were examined by hardness measurement and simulation using a finite element method. Tensile tests were conducted using tensile specimens extracted from the IF-HPS-processed sheet. Advent of high strain rate superplasticity with the total elongation of more than 400 pct was confirmed by pulling the tensile specimens with an initial strain rate of 2.0 × 10-2 s-1 at a temperature as low as 1073 K. The formability of the IF-HPS-processed sheet was confirmed by successful cup forming. It was also confirmed that the restoration after the superplastic deformation was feasible by subjecting to conventional heat treatment used for Inconel 718.

Acceptance of two US Department of Agriculture commodity whole-grain products: a school-based study in Texas and Minnesota.

PubMed

Chu, Yen Li; Warren, Cynthia A; Sceets, Christine E; Murano, Peter; Marquart, Len; Reicks, Marla

2011-09-01

Whole-grain intake among children and adolescents is below national recommendations, prompting efforts to increase intake in schools. The purpose of this study was to compare the acceptance of whole-grain pancakes and tortillas to refined grain counterparts when served as part of the school meal. Data were collected at 10 schools in Minnesota and seven schools in Texas during the Spring and Fall semesters of 2009. Three pancake and two tortilla products of varying red or white whole-wheat flour content were each served an average of four times per school. Aggregate plate waste was collected and percent consumption used to assess acceptance. Students rated each product on overall liking, taste, color, and softness on 5-point (elementary schools) or 9-point hedonic scales (middle and high schools). Analysis of covariance was used to compare intake and rating scores of all products. For all children, intake of whole-grain products was substantial (percent consumption ranging from 67% to 75%). No differences were noted in consumption of whole-wheat pancakes compared to refined wheat pancakes, while consumption of whole-wheat tortillas was lower than refined products. In elementary schools, overall liking scores of pancakes made with red whole-wheat and both types of whole-wheat tortillas were lower than refined products. However, in middle and high schools, overall liking scores of 100% red whole-wheat pancakes and 66% white whole-wheat tortillas were similar to refined products. Substituting refined grain with whole-grain options represents a viable approach to increasing consumption of whole-grain products in schools. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

Combination of dynamic transformation and dynamic recrystallization for realizing ultrafine-grained steels with superior mechanical properties

PubMed Central

Zhao, Lijia; Park, Nokeun; Tian, Yanzhong; Shibata, Akinobu; Tsuji, Nobuhiro

2016-01-01

Dynamic recrystallization (DRX) is an important grain refinement mechanism to fabricate steels with high strength and high ductility (toughness). The conventional DRX mechanism has reached the limitation of refining grains to several microns even though employing high-strain deformation. Here we show a DRX phenomenon occurring in the dynamically transformed (DT) ferrite, by which the required strain for the operation of DRX and the formation of ultrafine grains is significantly reduced. The DRX of DT ferrite shows an unconventional temperature dependence, which suggests an optimal condition for grain refinement. We further show that new strategies for ultra grain refinement can be evoked by combining DT and DRX mechanisms, based on which fully ultrafine microstructures having a mean grain size down to 0.35 microns can be obtained without high-strain deformation and exhibit superior mechanical properties. This study will open the door to achieving optimal grain refinement to nanoscale in a variety of steels requiring no high-strain deformation in practical industrial application. PMID:27966603

Grain Structure Control of Additively Manufactured Metallic Materials

PubMed Central

Faierson, Eric J.

2017-01-01

Grain structure control is challenging for metal additive manufacturing (AM). Grain structure optimization requires the control of grain morphology with grain size refinement, which can improve the mechanical properties of additive manufactured components. This work summarizes methods to promote fine equiaxed grains in both the additive manufacturing process and subsequent heat treatment. Influences of temperature gradient, solidification velocity and alloy composition on grain morphology are discussed. Equiaxed solidification is greatly promoted by introducing a high density of heterogeneous nucleation sites via powder rate control in the direct energy deposition (DED) technique or powder surface treatment for powder-bed techniques. Grain growth/coarsening during post-processing heat treatment can be restricted by presence of nano-scale oxide particles formed in-situ during AM. Grain refinement of martensitic steels can also be achieved by cyclic austenitizing in post-processing heat treatment. Evidently, new alloy powder design is another sustainable method enhancing the capability of AM for high-performance components with desirable microstructures.

Grain dynamics and plastic properties of highly refined materials

NASA Astrophysics Data System (ADS)

Lagos, Miguel; Retamal, César

2010-12-01

It has been shown that a grain boundary may undergo two competing classes of elastic instability when the in-plane shear stress exceeds the proper critical values. It may buckle acquiring a sinusoidal shape or may develop a periodic series of fissures, separating bands with a sigmoidal profile. The two instabilities lead to grain sliding, but the corresponding expressions relating the relative velocity between adjacent grains with stress do differ. The plastic properties for small strains were calculated for the two force laws, which we called force models A and B. A comparison of the theoretical results with published experimental data shows that model A, while giving predictions within the experimental uncertainties for a series of superplastic aluminium and titanium alloys, fails for Avesta 2304 steel. However, excellent results are obtained when model B is applied for this steel.

A new insight into ductile fracture of ultrafine-grained Al-Mg alloys.

PubMed

Yu, Hailiang; Tieu, A Kiet; Lu, Cheng; Liu, Xiong; Liu, Mao; Godbole, Ajit; Kong, Charlie; Qin, Qinghua

2015-04-08

It is well known that when coarse-grained metals undergo severe plastic deformation to be transformed into nano-grained metals, their ductility is reduced. However, there are no ductile fracture criteria developed based on grain refinement. In this paper, we propose a new relationship between ductile fracture and grain refinement during deformation, considering factors besides void nucleation and growth. Ultrafine-grained Al-Mg alloy sheets were fabricated using different rolling techniques at room and cryogenic temperatures. It is proposed for the first time that features of the microstructure near the fracture surface can be used to explain the ductile fracture post necking directly. We found that as grains are refined to a nano size which approaches the theoretical minimum achievable value, the material becomes brittle at the shear band zone. This may explain the tendency for ductile fracture in metals under plastic deformation.

A new insight into ductile fracture of ultrafine-grained Al-Mg alloys

NASA Astrophysics Data System (ADS)

Yu, Hailiang; Tieu, A. Kiet; Lu, Cheng; Liu, Xiong; Liu, Mao; Godbole, Ajit; Kong, Charlie; Qin, Qinghua

2015-04-01

It is well known that when coarse-grained metals undergo severe plastic deformation to be transformed into nano-grained metals, their ductility is reduced. However, there are no ductile fracture criteria developed based on grain refinement. In this paper, we propose a new relationship between ductile fracture and grain refinement during deformation, considering factors besides void nucleation and growth. Ultrafine-grained Al-Mg alloy sheets were fabricated using different rolling techniques at room and cryogenic temperatures. It is proposed for the first time that features of the microstructure near the fracture surface can be used to explain the ductile fracture post necking directly. We found that as grains are refined to a nano size which approaches the theoretical minimum achievable value, the material becomes brittle at the shear band zone. This may explain the tendency for ductile fracture in metals under plastic deformation.

Machining-induced deformation in stepped specimens of PH 13-8 Mo, 18 nickel maraging steel grade 200T1 and grain-refined HP 9-4-20

NASA Technical Reports Server (NTRS)

Wigley, D. A.

1985-01-01

The results of a study to evaluate the dimensional changes created during machining and subsequent cycling to cryogenic temperatures for three different metallic alloys are presented. Experimental techniques are described and results presented for 18 Ni Grade 200 maraging steel, PH-13-8 Mo stainless steel, and Grain-refined HP 9-4-20.

Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, N., E-mail: nirupamd@barc.gov.in; Sengupta, P.; Abraham, G.

Highlights: • Grain refinement was made in Zr–16 wt.% SS alloy while prepared by suction casting process. • Distribution of Laves phase, e.g., Zr{sub 2}(Fe, Cr) was raised in suction cast (SC) Zr–16 wt.% SS. • Corrosion resistance was improved in SC alloy compared to that of arc-melt-cast alloy. • Grain refinement in SC alloy assisted for an increase in its corrosion resistance. - Abstract: Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr–16 wt.% SS, a MWF alloymore » optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr{sub 2}(Fe, Cr)/α-Zr vs. hard phase: Zr{sub 3}(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr{sub 2}(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance.« less

A new insight into ductile fracture of ultrafine-grained Al-Mg alloys

PubMed Central

Yu, Hailiang; Tieu, A. Kiet; Lu, Cheng; Liu, Xiong; Liu, Mao; Godbole, Ajit; Kong, Charlie; Qin, Qinghua

2015-01-01

It is well known that when coarse-grained metals undergo severe plastic deformation to be transformed into nano-grained metals, their ductility is reduced. However, there are no ductile fracture criteria developed based on grain refinement. In this paper, we propose a new relationship between ductile fracture and grain refinement during deformation, considering factors besides void nucleation and growth. Ultrafine-grained Al-Mg alloy sheets were fabricated using different rolling techniques at room and cryogenic temperatures. It is proposed for the first time that features of the microstructure near the fracture surface can be used to explain the ductile fracture post necking directly. We found that as grains are refined to a nano size which approaches the theoretical minimum achievable value, the material becomes brittle at the shear band zone. This may explain the tendency for ductile fracture in metals under plastic deformation. PMID:25851228

Understanding Solidification Based Grain Refinement in Steels

DTIC Science & Technology

2014-12-18

sulfide.^^"^^ Another approach would be to react a sample of misch metal or rare earth silicide at elevated temperatures to form the desired oxide or...dislocation can travel through a metal crystal before being blocked by a grain boundary. Since the dislocation is impeded sooner, the material cannot...in the melt; 3) be wetted by the liquid metal ; and 4) have a similar crystallographic structure to the host metal . Using reference data and

Comparison Between Different Processing Schedules for the Development of Ultrafine-Grained Dual-Phase Steel

NASA Astrophysics Data System (ADS)

Karmakar, Anish; Sivaprasad, S.; Nath, S. K.; Misra, R. D. K.; Chakrabarti, Debalay

2014-05-01

A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite-martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500® simulator, maintaining a constant total strain ( ɛ = 1) and strain rate ( = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0 μm, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0 μm and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def, which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal, depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical

Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medlin, D. L.; Hattar, K.; Zimmerman, J. A.

Grain boundaries often develop faceted morphologies in systems for which the interfacial free energy depends on the boundary inclination. Although the mesoscale thermodynamic basis for such morphological evolution has been extensively studied, the influence of line defects, such as secondary grain boundary dislocations, on the facet configurations has not been thoroughly explored. In this paper, through a combination of atomistic simulations and electron microscopic observations, we examine in detail the structure of an asymmetric Σ = 5 [001] grain boundary in well-annealed, body-centered cubic (BCC) Fe. The observed boundary forms with a hill-and-valley morphology composed of nanoscale {310} and {210}more » facets. Our analysis clarifies the atomic structure of the {310}/{210} facet junctions and identifies the presence of an array of secondary grain boundary dislocations that are localized to these junctions. Analysis of the Burgers vectors of the grain boundary dislocations, which are of type (1/5)<310> and (1/5)<120>, shows that the defect density is consistent with that required to accommodate a small observed angular deviation from the exact Σ = 5 orientation relationship. As a result, these observations and analysis suggest a crucial role for secondary grain boundary dislocations in dictating the length-scale of grain boundary facets, a consideration which has not been included in prior analyses of facet evolution and equilibrium facet length.« less

Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe

DOE PAGES

Medlin, D. L.; Hattar, K.; Zimmerman, J. A.; ...

2016-11-16

Grain boundaries often develop faceted morphologies in systems for which the interfacial free energy depends on the boundary inclination. Although the mesoscale thermodynamic basis for such morphological evolution has been extensively studied, the influence of line defects, such as secondary grain boundary dislocations, on the facet configurations has not been thoroughly explored. In this paper, through a combination of atomistic simulations and electron microscopic observations, we examine in detail the structure of an asymmetric Σ = 5 [001] grain boundary in well-annealed, body-centered cubic (BCC) Fe. The observed boundary forms with a hill-and-valley morphology composed of nanoscale {310} and {210}more » facets. Our analysis clarifies the atomic structure of the {310}/{210} facet junctions and identifies the presence of an array of secondary grain boundary dislocations that are localized to these junctions. Analysis of the Burgers vectors of the grain boundary dislocations, which are of type (1/5)<310> and (1/5)<120>, shows that the defect density is consistent with that required to accommodate a small observed angular deviation from the exact Σ = 5 orientation relationship. As a result, these observations and analysis suggest a crucial role for secondary grain boundary dislocations in dictating the length-scale of grain boundary facets, a consideration which has not been included in prior analyses of facet evolution and equilibrium facet length.« less

Overview of refinement procedures within REFMAC5: utilizing data from different sources.

PubMed

Kovalevskiy, Oleg; Nicholls, Robert A; Long, Fei; Carlon, Azzurra; Murshudov, Garib N

2018-03-01

Refinement is a process that involves bringing into agreement the structural model, available prior knowledge and experimental data. To achieve this, the refinement procedure optimizes a posterior conditional probability distribution of model parameters, including atomic coordinates, atomic displacement parameters (B factors), scale factors, parameters of the solvent model and twin fractions in the case of twinned crystals, given observed data such as observed amplitudes or intensities of structure factors. A library of chemical restraints is typically used to ensure consistency between the model and the prior knowledge of stereochemistry. If the observation-to-parameter ratio is small, for example when diffraction data only extend to low resolution, the Bayesian framework implemented in REFMAC5 uses external restraints to inject additional information extracted from structures of homologous proteins, prior knowledge about secondary-structure formation and even data obtained using different experimental methods, for example NMR. The refinement procedure also generates the `best' weighted electron-density maps, which are useful for further model (re)building. Here, the refinement of macromolecular structures using REFMAC5 and related tools distributed as part of the CCP4 suite is discussed.

Method of refining 2,2-isopropylidenebis-3,5- dibromophenylene-4-oxydiethanol

NASA Technical Reports Server (NTRS)

Kobayashi, T.; Nawata, K.; Hiratsuka, K.

1982-01-01

A method of refining 2,2-isopropylidenebis-3,5-dibromophenylene-4-oxydiethanol is described which is characterized by recrystallization of 2,2-isopropylidenebis-3,5-dibromophenylene-4-oxydiethanol using one or more aromatic hydrocarbons such as benzene, xylene, toluene, ethylbenzene or pseudocumene.

Ultra fine grained Ti prepared by severe plastic deformation

NASA Astrophysics Data System (ADS)

Lukáč, F.; Čížek, J.; Knapp, J.; Procházka, I.; Zháňal, P.; Islamgaliev, R. K.

2016-01-01

The positron annihilation spectroscopy was employed for characterisation of defects in pure Ti with ultra fine grained (UFG) structure. UFG Ti samples were prepared by two techniques based on severe plastic deformation (SPD): (i) high pressure torsion (HPT) and (ii) equal channel angular pressing (ECAP). Although HPT is the most efficient technique for grain refinement, the size of HPT-deformed specimens is limited. On the other hand, ECAP is less efficient in grain refinement but enables to produce larger samples more suitable for industrial applications. Characterisation of defects by positron annihilation spectroscopy was accompanied by hardness testing in order to monitor the development of mechanical properties of UFG Ti.

Characterization of ultra-fine grained aluminum produced by accumulative back extrusion (ABE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alihosseini, H., E-mail: hamid.alihossieni@gmail.com; Materials Science and Engineering Department, Engineering School, Amirkabir University, Tehran; Faraji, G.

2012-06-15

In the present work, the microstructural evolutions and microhardness of AA1050 subjected to one, two and three passes of accumulative back extrusion (ABE) were investigated. The microstructural evolutions were characterized using transmission electron microscopy. The results revealed that applying three passes of accumulative back extrusion led to significant grain refinement. The initial grain size of 47 {mu}m was refined to the grains of 500 nm after three passes of ABE. Increasing the number of passes resulted in more decrease in grain size, better microstructure homogeneity and increase in the microhardness. The cross-section of ABEed specimen consisted of two different zones:more » (i) shear deformation zone, and (ii) normal deformation zone. The microhardness measurements indicated that the hardness increased from the initial value of 31 Hv to 67 Hv, verifying the significant microstructural refinement via accumulative back extrusion. - Highlights: Black-Right-Pointing-Pointer A significant grain refinement can be achieved in AA1050, Al alloy by applying ABE. Black-Right-Pointing-Pointer Microstructural homogeneity of ABEed samples increased by increasing the number of ABE cycles. Black-Right-Pointing-Pointer A substantial increase in the hardness, from 31 Hv to 67 Hv, was recorded.« less

Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

PubMed

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

2016-05-01

The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigations on the effect of grain size on hot tearing susceptibility of MgZn1Y2 alloy

NASA Astrophysics Data System (ADS)

Zhou, Z. J.; Liu, Z.; Wang, Y.; Mao, P. L.; Tang, W. R.; Zhou, Y.

2018-05-01

Effect of grain size on hot tearing susceptibility of MgZn1Y2 alloy was explored in the present paper. Based on the microstructure observation and phase constitution analysis results by the method of OM, SEM, EBSD and XRD, it was found that the addition of 0.2 wt% C2Cl6 or 0.5 wt% Zr could reduced the grain size significantly. The addition of Zr had the better effect than that of 0.2 wt% C2Cl6. The average grain size reduced from 55.48 μm to 20.64 μm, and the average grain shape aspect ratio reduced from 1.859 to 1.49 with the addition of Zr. Although the addition of 0.2 wt% C2Cl6 refined grain, it also reduced the amount of LPSO phase. It was also found that the dendrite coherent temperature (Tcoh) decreased with decreasing of the grain size of the alloy, while the dendrite coherent solid fraction ({{{{f}}}{{s}}}{{coh}}) increased with decreasing of the alloy. The modified Clyne-Davies model was used to predict the hot cracking susceptibility of the alloy. The predicted results indicated that the hot tearing susceptibility decreased with grain refinement. With addition of 0.2 wt% Zr, the predicted hot tearing sensitivity value was reduced by about 2.5 times than that of the alloy without the addition of Zr.

Whole-grain intake in middle school students achieves dietary guidelines for Americans and MyPlate recommendations when provided as commercially available foods: a randomized trial.

PubMed

Radford, Allyson; Langkamp-Henken, Bobbi; Hughes, Christine; Christman, Mary C; Jonnalagadda, Satya; Boileau, Thomas W; Thielecke, Frank; Dahl, Wendy J

2014-09-01

In accordance with the 2010 Dietary Guidelines for Americans, at least half of total grain intake should be whole grains. Adolescents are currently not consuming the recommended daily intake of whole grains. Research is needed to determine whether whole grains are acceptable to adolescents and whether changing their food environment to include whole-grain foods will improve intake. The aim of this study was to determine the effect of providing refined-grain or whole-grain foods to adolescents, with encouragement to eat three different grain-based foods per day, on total grain and whole-grain intakes. Middle school students (n=83; aged 11 to 15 years) were randomly assigned to either refined-grain or whole-grain foods for 6 weeks. Participants and their families were provided with weekly grains (eg, bread, pasta, and cereals), and participants were provided grain snacks at school. Intake of grains in ounce equivalents (oz eq) was determined through eight baseline and intervention targeted 24-hour diet recalls. Participants consumed 1.1±1.3 oz eq (mean±standard deviation) of whole grains at baseline, out of 5.3±2.4 oz eq of total grains. During intervention, whole-grain intake increased in the whole-grain group (0.9±1.0 to 3.9±1.8 oz eq/day), whereas those in the refined-grain group reduced whole-grain intake (1.3±1.6 to 0.3±0.3 oz eq/day; P<0.002, group by time period interaction). Total grain intake achieved was 6.4±2.1 oz eq/day and did not differ across intervention groups. Providing adolescents with whole-grain foods in their school and home environments was an effective means of achieving recommendations. Copyright © 2014 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Use of B4C powder for preparing in situ Al-Ti-B-C inoculant in Al-Ti melt and its refining effect on A356 alloy

NASA Astrophysics Data System (ADS)

Liu, Shuiqing; Cui, Chunxiang; Wang, Xin; Zhao, Lichen; Sun, Yijiao; Shi, Jiejie; Cui, Sen; Ding, Jinhua

2018-01-01

A novel preparation technology of Al-Ti-B-C inoculant with uniform microstructure is prepared using B4C powder instead of graphite in Al-Ti melt reaction method in this study. It is found that the addition of B4C powder improves the wettability between carbon element and liquid aluminum and reduce the tendency to the gravity segregation simultaneously. The result shows that Al-Ti-B-C inoculant using B4C powder presents excellent grain refinement performance than the conventional approach. After T6 heat treatment, the ultimate tensile strength, the yield strength and elongation of A356 alloy are increased to 292 ± 6 MPa, 238 ± 7 MPa and 8.2% ± 0.5% from 260 ± 7 MPa, 218 ± 5 MPa and 4.9% ± 0.6% by addition of Al-Ti-B-C inoculant with a very small ratio of 0.3% in weight. The increase of strength in Al-Ti-B-C refined alloy is attributed to the grain refinement of primary α-Al, while the increase of ductility results from the submicron particles in Al-Ti-B-C inoculant adsorb impurity atoms as well as decreased grain size.

Whole-grain intake is associated with body mass index in college students.

PubMed

Rose, Nick; Hosig, Kathy; Davy, Brenda; Serrano, Elena; Davis, Linda

2007-01-01

To measure whole-grain intake in college students and determine the association with body mass index (BMI). Cross-sectional convenience sample of college students enrolled in an introductory nutrition course. Large state university. 159 college students, mean age: 19.9. Intake of whole grains, refined grains, calories, and fiber from food records; BMI determined from height and weight measurements. Analysis of variance with linear contrasts; participants grouped by BMI category (P<.05). Average intake of cereal grains was 5.4 servings per day, of which whole-grain intake accounted for an average of 0.7 servings per day. Whole-grain intake was significantly higher in normal weight students than in overweight and obese students (based on BMI). The low intake of whole grains in this population of college students indicates the need for interventions aiming to increase whole-grain intake to the recommended minimum of 3 servings per day. College students who are concerned about their body weight may be motivated to increase their intake of whole-grain foods; however, their intake of whole grains is likely to be influenced by the availability of these food items in campus dining halls and other locations around the college campus.

Adaptive mesh refinement for characteristic grids

NASA Astrophysics Data System (ADS)

Thornburg, Jonathan

2011-05-01

I consider techniques for Berger-Oliger adaptive mesh refinement (AMR) when numerically solving partial differential equations with wave-like solutions, using characteristic (double-null) grids. Such AMR algorithms are naturally recursive, and the best-known past Berger-Oliger characteristic AMR algorithm, that of Pretorius and Lehner (J Comp Phys 198:10, 2004), recurses on individual "diamond" characteristic grid cells. This leads to the use of fine-grained memory management, with individual grid cells kept in two-dimensional linked lists at each refinement level. This complicates the implementation and adds overhead in both space and time. Here I describe a Berger-Oliger characteristic AMR algorithm which instead recurses on null slices. This algorithm is very similar to the usual Cauchy Berger-Oliger algorithm, and uses relatively coarse-grained memory management, allowing entire null slices to be stored in contiguous arrays in memory. The algorithm is very efficient in both space and time. I describe discretizations yielding both second and fourth order global accuracy. My code implementing the algorithm described here is included in the electronic supplementary materials accompanying this paper, and is freely available to other researchers under the terms of the GNU general public license.

In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys

PubMed Central

Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

2014-01-01

The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e., strong enough, to avoid hot tear formation. PMID:28788507

In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys.

PubMed

Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

2014-02-12

The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e. , strong enough, to avoid hot tear formation.

Effects on satiation, satiety and food intake of wholegrain and refined grain pasta.

PubMed

Cioffi, Iolanda; Ibrugger, Sabine; Bache, Jessica; Thomassen, Mette Torp; Contaldo, Franco; Pasanisi, Fabrizio; Kristensen, Mette

2016-12-01

Wholegrains have received much attention in recent years due to their role in prevention of obesity and its comorbidities. Many studies about energy regulation are focused on the effect between meals (satiety), but the effect within meal (satiation) for wholegrain foods has not been extensively studied. The objective was to investigate the effect of WG pasta (WGP) compared to refined grain pasta (RGP), on ad libitum energy intake (EI) within and at the subsequent meal as well as appetite. Two different ad libitum lunch meals (study A) and two different iso-caloric lunch meals (study B) were administered in sixteen overweight/obese subjects in a crossover design. The test meals consisted of RGP and WGP served with tomato sauce. Study A: the ad libitum lunch meal was consumed then EI registered. Study B: the iso-caloric lunch meal was served, then subjective appetite sensation and breath hydrogen excretion were assessed for 240 min followed by an ad libitum meal where EI was calculated. Overall, WGP did not significantly differ in the effect on ad libitum EI within meal (p = 0.23) in study A. In study B, WGP resulted in an increased sensation of satiety (p < 0.001) and lower ratings of hunger (p < 0.001) without increased in breath hydrogen excretion (p = 0.11). Again, no overall effect on EI at the subsequent meal was seen (p = 0.12). In conclusion, WGP increased satiety, diminished hunger without modifying energy intake at the subsequent meals. Copyright © 2016. Published by Elsevier Ltd.

Natural Variation in the Promoter of GSE5 Contributes to Grain Size Diversity in Rice.

PubMed

Duan, Penggen; Xu, Jinsong; Zeng, Dali; Zhang, Baolan; Geng, Mufan; Zhang, Guozheng; Huang, Ke; Huang, Luojiang; Xu, Ran; Ge, Song; Qian, Qian; Li, Yunhai

2017-05-01

The utilization of natural genetic variation greatly contributes to improvement of important agronomic traits in crops. Understanding the genetic basis for natural variation of grain size can help breeders develop high-yield rice varieties. In this study, we identify a previously unrecognized gene, named GSE5, in the qSW5/GW5 locus controlling rice grain size by combining the genome-wide association study with functional analyses. GSE5 encodes a plasma membrane-associated protein with IQ domains, which interacts with the rice calmodulin protein, OsCaM1-1. We found that loss of GSE5 function caused wide and heavy grains, while overexpression of GSE5 resulted in narrow grains. We showed that GSE5 regulates grain size predominantly by influencing cell proliferation in spikelet hulls. Three major haplotypes of GSE5 (GSE5, GSE5 DEL1+IN1 , and GSE5 DEL2 ) in cultivated rice were identified based on the deletion/insertion type in its promoter region. We demonstrated that a 950-bp deletion (DEL1) in indica varieties carrying the GSE5 DEL1+IN1 haplotype and a 1212-bp deletion (DEL2) in japonica varieties carrying the GSE5 DEL2 haplotype associated with decreased expression of GSE5, resulting in wide grains. Further analyses indicate that wild rice accessions contain all three haplotypes of GSE5, suggesting that the GSE5 haplotypes present in cultivated rice are likely to have originated from different wild rice accessions during rice domestication. Taken together, our results indicate that the previously unrecognized GSE5 gene in the qSW5/GW5 locus, which is widely utilized by rice breeders, controls grain size, and reveal that natural variation in the promoter region of GSE5 contributes to grain size diversity in rice. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

Method to grow carbon thin films consisting entirely of diamond grains 3-5 nm in size and high-energy grain boundaries

DOEpatents

Carlisle, John A.; Auciello, Orlando; Birrell, James

2006-10-31

An ultrananocrystalline diamond (UNCD) having an average grain size between 3 and 5 nanometers (nm) with not more than about 8% by volume diamond having an average grain size larger than 10 nm. A method of manufacturing UNCD film is also disclosed in which a vapor of acetylene and hydrogen in an inert gas other than He wherein the volume ratio of acetylene to hydrogen is greater than 0.35 and less than 0.85, with the balance being an inert gas, is subjected to a suitable amount of energy to fragment at least some of the acetylene to form a UNCD film having an average grain size of 3 to 5 nm with not more than about 8% by volume diamond having an average grain size larger than 10 nm.

Grain size effect on the permittivity of La1.5Sr0.5NiO4 nanoparticles

NASA Astrophysics Data System (ADS)

Dang Thanh, Tran; Van Hong, Le

2009-09-01

Using the annealing at different temperatures the La1.5Sr0.5NiO4 ceramic samples with different mean grain size were manufactured. Mean grain size () of the samples was evaluated by Warren-Averbach method and their SEM images. The obtained results of both methods are almost the same, changing from 16.2 to 95 nm in dependence on the annealing temperature. The frequency dependence of dielectric constant in the frequency range of (1-13 MHz) was recorded for all samples. The real (ɛ') and the imaginary parts (ɛ") of the permittivity of La1.5Sr0.5NiO4 samples abnormally depend on the frequency, exhibiting a dielectric resonance around 500 kHz. R-L-C in series equivalent-circuit fitted well for the obtained result. It was supposed that there exists magnetic contribution in material that suggests the material is a multiferroic one. Dependence of the (ɛ') on the mean grain size supposed that the colossal dielectric property is an intrinsic behaviour of La1.5Sr0.5NiO4 material.

Refinement Types ML

DTIC Science & Technology

1994-03-16

105 2.10 Decidability ........ ................................ 116 3 Declaring Refinements of Recursive Data Types 165 3.1...However, when we introduce polymorphic constructors in Chapter 5, tuples will become a polymorphic data type very similar to other polymorphic data types...terminate. 0 Chapter 3 Declaring Refinements of Recursive Data Types 3.1 Introduction The previous chapter defined refinement type inference in terms of

The effect of scandium addition on microstructure and mechanical properties of Al–Si–Mg alloy: A multi-refinement modifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Cong, E-mail: xucong55555@gmail.com; Xiao, Wenlong, E-mail: wlxiao@buaa.edu.cn; Hanada, Shuji

2015-12-15

Effect of scandium (Sc) additions on the microstructure, mechanical properties and fracture behavior of Al–Si–Mg casting alloy (F357) were systematically investigated. It was found that Sc addition caused a multi-refining efficiency on the microstructure of as-cast F357 alloy, including refinement of grains and secondary dendrite arm spacing (SDAS), modification of eutectic Si and harmless disposal of β-Al{sub 5}FeSi phase. Subsequent T6 heat treatment had further induced the complete spheroidization of eutectic Si and precipitation of fine secondary Al{sub 3}Sc dispersoids in the Sc modified alloys. Thus the mechanical properties, especially the ductility, were significantly enhanced by the addition of Scmore » combined with the heat treatment. The highest ultimate tensile strength, yield strength and elongation were achieved in 0.8 wt.% Sc modified F357 alloy combined with T6 heat treatment. Furthermore, fractographic examinations indicated that the ductile fracture mechanism served as a dominate role in the modified alloys due to the formation of fine, deep and uniformly distributed dimples. - Highlights: • Detailed characterization of the multi-refining microstructure of Sc modified F357 alloy was performed. • The multi-refinement was proposed to refine grain and SDAS, modify eutectic Si and β-phase. • Sc modifier combined with T6 treatment is effective in improving tensile properties. • Modification of eutectic Si in F357 alloy with Sc is consistent with the IIT mechanism.« less

Reconstruction of three-dimensional grain structure in polycrystalline iron via an interactive segmentation method

NASA Astrophysics Data System (ADS)

Feng, Min-nan; Wang, Yu-cong; Wang, Hao; Liu, Guo-quan; Xue, Wei-hua

2017-03-01

Using a total of 297 segmented sections, we reconstructed the three-dimensional (3D) structure of pure iron and obtained the largest dataset of 16254 3D complete grains reported to date. The mean values of equivalent sphere radius and face number of pure iron were observed to be consistent with those of Monte Carlo simulated grains, phase-field simulated grains, Ti-alloy grains, and Ni-based super alloy grains. In this work, by finding a balance between automatic methods and manual refinement, we developed an interactive segmentation method to segment serial sections accurately in the reconstruction of the 3D microstructure; this approach can save time as well as substantially eliminate errors. The segmentation process comprises four operations: image preprocessing, breakpoint detection based on mathematical morphology analysis, optimized automatic connection of the breakpoints, and manual refinement by artificial evaluation.

Experimental investigation of grain boundaries misorientations and nano twinning induced strengthening on addition of silicon carbide in pulse electrodeposited nickel tungsten composite coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, O.S. Asiq; Wasekar, Nitin P.; Sundararajan, G.

Nanoindentation was performed on silicon carbide (SiC) reinforced pulse electrodeposited nickel-tungsten (Ni-W) composite coating. Addition of 5 vol.% of SiC in Ni-W coating increased the hardness from 10.31 ± 0.65 GPa to 14.32 ± 0.63 GPa and elastic modulus from 119.74 ± 3.15 GPa to 139.26 ± 2.09 GPa. Increased hardness and elastic modulus directly translates to the improved strengthening in the coating. An experimental investigation of strengthening mechanism was carried out in Ni-W-5 vol.% SiC alloy. Two simultaneous phenomena viz. grain refinement and increased internal strain was observed, which increased the dislocation density from 5.51 × 10{sup 18} m{supmore » −2} to 1.346 × 10{sup 19} m{sup −2} on reinforcement of 5 vol.% of SiC in Ni-W coating. Increased dislocation density promoted the formation of grain boundary misorientations and nano twinning. Low angle grain boundary, high angle grain boundary and nano twinning were identified using high resolution transmission electron microscope (HR-TEM) image and their role in strengthening mechanism was discussed in details. - Highlights: • SiC reinforced pulse electrodeposition Ni-W coating was deposited on steel. • Nanoindentation showed the increased mechanical properties on addition of SiC. • Grain refinement and increased internal strain was observed in Ni-W-SiC coating. • Dislocation density increased on reinforcement of SiC in Ni-W coating. • Increased dislocation density triggered grain boundary misorientation and twinning.« less

Cyclic Spin Testing of Superalloy Disks With a Dual Grain Microstructure

NASA Technical Reports Server (NTRS)

Gayda, John; Kantzos, Pete

2005-01-01

An aggressive cyclic spin test program was run to verify the reliability of superalloy disks with a dual grain structure, fine grain bore and coarse grain rim, utilizing a disk design with web holes bisecting the grain size transition zone. Results of these tests were compared with conventional disks with uniform grain structures. Analysis of the test results indicated the cyclic performance of disks with a dual grain structure could be estimated to a level of accuracy which does not appear to prohibit the use of this technology in advanced gas turbine engines, although further refinement of lifing methodology is clearly warranted.

Effect of prior-austenite grain refinement on microstructure, mechanical properties and thermal embrittlement of 9Cr-1Mo-0.1C steel

NASA Astrophysics Data System (ADS)

Karthikeyan, T.; Dash, Manmath Kumar; Ravikirana; Mythili, R.; Panneer Selvi, S.; Moitra, A.; Saroja, S.

2017-10-01

The effect of 'conventional normalizing and tempering' (CNT) and 'double austenitization based normalizing and tempering' (DNT) heat treatments on the microstructure, tensile, creep and impact toughness properties of 9Cr-1Mo steel has been studied. The tempered martensite microstructure obtained through DNT treatment exhibited smaller sizes of prior-austenite grains/martensite packets (28 μm/11 μm) compared to the CNT treatment (44 μm/14 μm). The tempered martensite morphology was largely retained after long-term thermal aging at 550 °C/5000 h, while the M23C6 and M2(C,N) type of precipitates were found to act as nucleation sites for precipitation of brittle Fe2Mo Laves phase. The grain refinement by DNT was found to be beneficial for minimizing the ductile-to-brittle transition characteristics (25 °C lower ductile-to-brittle transition temperature and 70 J higher upper shelf energy) over the CNT. Thermal embrittlement occurred in both heated treated steels, but the transition temperature of aged DNT steel remained below room temperature. Fractured Charpy specimens revealed ductile failure by void coalescence for high temperature tests, and a quasi-cleavage fracture at low temperatures with few isolated occurrence of intergranular crack in thermal embrittled steel. The DNT treated steel resulted in similar or better tensile and creep properties, when compared to the CNT treatment. The homogeneous fine grained tempered martensite microstructure obtained by DNT treatment resulted in improved embrittlement resistance and mechanical properties over the conventional treatment.

Analysis of Microstructure Refinement During Single-Pass and Multi-Pass Friction Stir Processing of Nial Propeller Bronze

DTIC Science & Technology

2010-09-01

on an Optical Micrograph of the Transverse View of Single-Pass NAB. After [5]............................................... 6 Figure 4 . Vertical...deformed and 6 elongated but does not see the same refinement that is seen inside the SZ [ 4 ]. The grain structure right outside the TMAZ will also...including grinding, polishing, and electropolishing . The first step was to grind the surface using a Buehler ECOMET 4 Variable Speed Grinder

Method for producing ultrafine-grained materials using repetitive corrugation and straightening

DOEpatents

Zhu, Yuntian T.; Lowe, Terry C.; Jiang, Honggang; Huang, Jianyu

2001-01-01

A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

Whole grain-rich diet reduces body weight and systemic low-grade inflammation without inducing major changes of the gut microbiome: a randomised cross-over trial.

PubMed

Roager, Henrik Munch; Vogt, Josef K; Kristensen, Mette; Hansen, Lea Benedicte S; Ibrügger, Sabine; Mærkedahl, Rasmus B; Bahl, Martin Iain; Lind, Mads Vendelbo; Nielsen, Rikke L; Frøkiær, Hanne; Gøbel, Rikke Juul; Landberg, Rikard; Ross, Alastair B; Brix, Susanne; Holck, Jesper; Meyer, Anne S; Sparholt, Morten H; Christensen, Anders F; Carvalho, Vera; Hartmann, Bolette; Holst, Jens Juul; Rumessen, Jüri Johannes; Linneberg, Allan; Sicheritz-Pontén, Thomas; Dalgaard, Marlene D; Blennow, Andreas; Frandsen, Henrik Lauritz; Villas-Bôas, Silas; Kristiansen, Karsten; Vestergaard, Henrik; Hansen, Torben; Ekstrøm, Claus T; Ritz, Christian; Nielsen, Henrik Bjørn; Pedersen, Oluf Borbye; Gupta, Ramneek; Lauritzen, Lotte; Licht, Tine Rask

2017-11-01

To investigate whether a whole grain diet alters the gut microbiome and insulin sensitivity, as well as biomarkers of metabolic health and gut functionality. 60 Danish adults at risk of developing metabolic syndrome were included in a randomised cross-over trial with two 8-week dietary intervention periods comprising whole grain diet and refined grain diet, separated by a washout period of ≥6 weeks. The response to the interventions on the gut microbiome composition and insulin sensitivity as well on measures of glucose and lipid metabolism, gut functionality, inflammatory markers, anthropometry and urine metabolomics were assessed. 50 participants completed both periods with a whole grain intake of 179±50 g/day and 13±10 g/day in the whole grain and refined grain period, respectively. Compliance was confirmed by a difference in plasma alkylresorcinols (p<0.0001). Compared with refined grain, whole grain did not significantly alter glucose homeostasis and did not induce major changes in the faecal microbiome. Also, breath hydrogen levels, plasma short-chain fatty acids, intestinal integrity and intestinal transit time were not affected. The whole grain diet did, however, compared with the refined grain diet, decrease body weight (p<0.0001), serum inflammatory markers, interleukin (IL)-6 (p=0.009) and C-reactive protein (p=0.003). The reduction in body weight was consistent with a reduction in energy intake, and IL-6 reduction was associated with the amount of whole grain consumed, in particular with intake of rye. Compared with refined grain diet, whole grain diet did not alter insulin sensitivity and gut microbiome but reduced body weight and systemic low-grade inflammation. NCT01731366; Results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The role of grain size and shape in the strengthening of dispersion hardened nickel alloys

NASA Technical Reports Server (NTRS)

Wilcox, B. A.; Clauer, A. H.

1972-01-01

Thermomechanical processing was used to develop various microsstructures in Ni, Ni-2ThO2, Ni-20Cr, Ni-20CR-2ThO2, Ni-20Cr-10W-and Ni-20Cr-10W-2ThO2. The yield strength at 25 C increased with substructure refinement according to the Hall-Petch relation, and substructure refinement was a much more potent means of strengthening than was dispersion hardening. At elevated temperature (1093 C), the most important microstructural feature affecting strength was the grain aspect ratio (grain length, L, divided by grain width, 1. The yield strength and creep strength increased linearly with increasing L/1.

Size and density distribution of very small dust grains in the Barnard 5 cloud

NASA Technical Reports Server (NTRS)

Lis, Dariusz C.; Leung, Chun Ming

1991-01-01

The effects of the temperature fluctuations in small graphite grains on the energy spectrum and the IR surface brightness of an isolated dust cloud heated externally by the interstellar radiation field were investigated using a series of models based on a radiation transport computer code. This code treats self-consistently the thermal coupling between the transient heating of very small dust grains and the equilibrium heating of conventional large grains. The model results were compared with the IRAS observations of the Barnard 5 (B5) cloud, showing that the 25-micron emission of the cloud must be produced by small grains with a 6-10 A radius, which also contribute about 50 percent to the observed 12-micron emission. The remaining 12 micron flux may be produced by the polycyclic aromatic hydrocarbons. The 60-and 100-micron radiation is dominated by emission from large grains heated under equilibrium conditions.

Dietary substitution of whole grains for refined grains favorably effects fiber intake and energy metabolism in adults

USDA-ARS?s Scientific Manuscript database

Whole grain-rich diets are consistently associated with lower adiposity in observational studies. However, clinical trials have failed to substantiate this association or identify underlying mechanisms. The inconsistency has been suggested to be due to trial methodology including suboptimal dietary ...

Recent Uptrend in Whole-Grain Intake Is Absent for Low-Income Adolescents, National Health and Nutrition Examination Survey, 2005-2012.

PubMed

Tester, June M; Leung, Cindy W; Leak, Tashara M; Laraia, Barbara A

2017-07-06

Whole-grain consumption reduces risk of chronic disease, yet adolescents consume suboptimal amounts. It is unclear whether trends in consumption of whole grains have been positive among adolescents, and research assessing disparities by socioeconomic status is limited. The objective of our study was to evaluate recent trends in whole-grain consumption by US adolescents. We examined data on 3,265 adolescents aged 13 to18 years from the National Health and Nutrition Examination Survey (NHANES) 2005-2012. Intake of whole and refined grains was analyzed by using generalized linear models, and odds of no whole-grain intake were examined with logistic regression, adjusting for socioeconomic and demographic factors. We evaluated trends and examined heterogeneity of trends with respect to annual household income. Daily whole-grain consumption among adolescents increased overall by about a quarter-ounce-equivalent per day (oz-eq/d) (P trend <.001). We found a significant relationship between whole-grain intake and income. Daily whole grains (recommended as ≥3 oz-eq/d), increased (0.6 to 1.0 oz-eq/d) among high-income adolescents (P trend < .001) but remained at 0.5 oz-eq/d for low-income adolescents. The ratio of whole grains to total grains (recommended to be at least 50%) rose from 7.6% to 14.2% for high-income adolescents (P trend < .001), with no significant trend for the low-income group. Consumption of refined grains did not change. Odds of having no whole grains trended downward, but only for the high-income adolescents (P trend = .01). These data show significant (albeit modest) trends toward increased intake of whole grains among high-income adolescents nationwide that are absent among low-income peers. Future interventions and policies should address barriers to whole-grain consumption among this vulnerable group.

Investigating the effect of multiple grain-grain interfaces on electric transport behavior of [50 wt% BaFe12O19-50 wt% Na0.5Bi0.5TiO3] magnetoelectric nanocomposite system

NASA Astrophysics Data System (ADS)

Pattanayak, Ranjit; Raut, Subhajit; Dash, Tapan; Mohapatra, Soumyaranjan; Muduli, Rakesh; Panigrahi, Simanchala

2017-05-01

Polycrystalline [50 wt% BaFe12O19 (BaM)-50 wt% Na0.5Bi0.5TiO3 (NBT)] particulate novel magnetoelectric nanocomposite system was successfully fabricated by solid state reaction technique. The Rietveld refinement of X-ray diffraction pattern was provided the evidence about the pure phase formation of desired nanocomposite system as well as the presence of both ferrimagnetic (FM) BaM & ferroelectric (FE) NBT phases separately. The Field Scanning Electron Micrograph (FESEM) and Scanning Tunneling Electron Micrograph (STEM) explored the information about grain size and connectivity of the composite system. The XPS study was helped to examine the presence of oxygen vacancy (Ov) as well as multi oxidation states of transition metal ions for nanocomposite system. In this report we have systematically examined the conduction mechanism of different interfaces (BaM-BaM, BaM-NBT and NBT-NBT) by the help of complex impedance spectroscopy technique. From our investigation it was observed that, different interfaces activates at different temperature ranges. Due to absence of OV, BaM-NBT interfaces conduction dominants over BaM-BaM interfaces conduction even at room temperature (RT). The mechanism behind the appeared high dielectric loss (tanδ) at RT which was reduced when NBT-NBT interfaces were activates at higher temperature was explained by Maxwell-Wagner type interfacial polarization concept.

Influence of attrition milling on nano-grain boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rawers, J.; Cook, D.

1999-03-01

Nanostructured materials have a relatively large proportion of their atoms associated with the grain boundary, and the method used to develop the nano-grains has a strong influence on the resulting grain boundary structure. In this study, attrition milling iron powders and blends of iron powders produced micron-size particles composed of nano-size grains. Mechanical cold-working powder resulted in dislocation generation, multiplication, and congealing that produced grain refinement. As the grain size approached nano-dimensions, dislocations were no longer sustained within the grain and once generated, rapidly diffused to the grain boundary. Dislocations on the grain boundary strained the local lattice structure which,more » as the grain size decreased, became the entire grain. Mechanical alloying of substitutional aluminium atoms into iron powder resulted in the aluminium atoms substituting for iron atoms in the grain boundary cells and providing a grain boundary structure similar to that of the iron powder processed in argon. Attrition milling iron powder in nitrogen gas resulted in nitrogen atoms being adsorbed onto the particle surface. Continued mechanical milling infused the nitrogen atoms into interstitial lattice sites on the grain boundary which also contributed to expanding and straining the local lattice.« less

Health benefits of ancient grains. Comparison among bread made with ancient, heritage and modern grain flours in human cultured cells.

PubMed

Valli, Veronica; Taccari, Annalisa; Di Nunzio, Mattia; Danesi, Francesca; Bordoni, Alessandra

2018-05-01

Nowadays the higher nutritional value of whole grains compared to refined grains is recognized. In the last decade, there has been a renewed interest in the ancient wheat varieties for producing high-value food products with enhanced health benefits. This study compared two ancient grains, two heritage grains, and four modern grains grown in the same agronomic conditions considering not only their chemical characteristics, but also their biological effects. Whole grain flours were obtained and used to make bread. Bread was in vitro digested, the digesta were supplemented to HepG2 cells, and the biological effects of supplementation were evaluated. In addition, cells previously supplemented with the different digested bread types were then exposed to inflammatory agents to evidence possible protective effects of the pre-treatments. Despite the impossibility to discriminate bread made with different grains based on their chemical composition, results herein reported evidence that their supplementation to cultured cells exerts different effects, confirming the potential health benefits of ancient grains. This research represents an advancement for the evaluation of the apparent positive effects of ancient grains and the formulation of cereal-based products with added nutritional value. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recent Uptrend in Whole-Grain Intake Is Absent for Low-Income Adolescents, National Health and Nutrition Examination Survey, 2005–2012

PubMed Central

Leung, Cindy W.; Leak, Tashara M.; Laraia, Barbara A.

2017-01-01

Introduction Whole-grain consumption reduces risk of chronic disease, yet adolescents consume suboptimal amounts. It is unclear whether trends in consumption of whole grains have been positive among adolescents, and research assessing disparities by socioeconomic status is limited. The objective of our study was to evaluate recent trends in whole-grain consumption by US adolescents. Methods We examined data on 3,265 adolescents aged 13 to18 years from the National Health and Nutrition Examination Survey (NHANES) 2005–2012. Intake of whole and refined grains was analyzed by using generalized linear models, and odds of no whole-grain intake were examined with logistic regression, adjusting for socioeconomic and demographic factors. We evaluated trends and examined heterogeneity of trends with respect to annual household income. Results Daily whole-grain consumption among adolescents increased overall by about a quarter-ounce–equivalent per day (oz-eq/d) (P trend <.001). We found a significant relationship between whole-grain intake and income. Daily whole grains (recommended as ≥3 oz-eq/d), increased (0.6 to 1.0 oz-eq/d) among high-income adolescents (P trend < .001) but remained at 0.5 oz-eq/d for low-income adolescents. The ratio of whole grains to total grains (recommended to be at least 50%) rose from 7.6% to 14.2% for high-income adolescents (P trend < .001), with no significant trend for the low-income group. Consumption of refined grains did not change. Odds of having no whole grains trended downward, but only for the high-income adolescents (P trend = .01). Conclusion These data show significant (albeit modest) trends toward increased intake of whole grains among high-income adolescents nationwide that are absent among low-income peers. Future interventions and policies should address barriers to whole-grain consumption among this vulnerable group. PMID:28682743

Electrochemical Behavior Assessment of Micro- and Nano-Grained Commercial Pure Titanium in H2SO4 Solutions

NASA Astrophysics Data System (ADS)

Fattah-alhosseini, Arash; Ansari, Ali Reza; Mazaheri, Yousef; Karimi, Mohsen

2017-02-01

In this study, the electrochemical behavior of commercial pure titanium with both coarse-grained (annealed sample with the average grain size of about 45 µm) and nano-grained microstructure was compared by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Nano-grained Ti, which typically has a grain size of about 90 nm, is successfully made by six-cycle accumulative roll-bonding process at room temperature. Potentiodynamic polarization plots and impedance measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure Ti in H2SO4 solutions. Mott-Schottky analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and grain refinement did not change the semiconductor type of passive films. Also, Mott-Schottky analysis showed that the donor densities decreased as the grain size of the samples reduced. Finally, all electrochemical tests showed that the electrochemical behavior of the nano-grained sample was improved compared to that of annealed pure Ti, mainly due to the formation of thicker and less defective oxide film.

Molecular dynamics-based refinement and validation for sub-5 Å cryo-electron microscopy maps.

PubMed

Singharoy, Abhishek; Teo, Ivan; McGreevy, Ryan; Stone, John E; Zhao, Jianhua; Schulten, Klaus

2016-07-07

Two structure determination methods, based on the molecular dynamics flexible fitting (MDFF) paradigm, are presented that resolve sub-5 Å cryo-electron microscopy (EM) maps with either single structures or ensembles of such structures. The methods, denoted cascade MDFF and resolution exchange MDFF, sequentially re-refine a search model against a series of maps of progressively higher resolutions, which ends with the original experimental resolution. Application of sequential re-refinement enables MDFF to achieve a radius of convergence of ~25 Å demonstrated with the accurate modeling of β-galactosidase and TRPV1 proteins at 3.2 Å and 3.4 Å resolution, respectively. The MDFF refinements uniquely offer map-model validation and B-factor determination criteria based on the inherent dynamics of the macromolecules studied, captured by means of local root mean square fluctuations. The MDFF tools described are available to researchers through an easy-to-use and cost-effective cloud computing resource on Amazon Web Services.

Perspective: A Definition for Whole-Grain Food Products-Recommendations from the Healthgrain Forum.

PubMed

Ross, Alastair B; van der Kamp, Jan-Willem; King, Roberto; Lê, Kim-Anne; Mejborn, Heddie; Seal, Chris J; Thielecke, Frank

2017-07-01

Whole grains are a key component of a healthy diet, and enabling consumers to easily choose foods with a high whole-grain content is an important step for better prevention of chronic disease. Several definitions exist for whole-grain foods, yet these do not account for the diversity of food products that contain cereals. With the goal of creating a relatively simple whole-grain food definition that aligns with whole-grain intake recommendations and can be applied across all product categories, the Healthgrain Forum, a not-for-profit consortium of academics and industry working with cereal foods, established a working group to gather input from academics and industry to develop guidance on labeling the whole-grain content of foods. The Healthgrain Forum recommends that a food may be labeled as "whole grain" if it contains ≥30% whole-grain ingredients in the overall product and contains more whole grain than refined grain ingredients, both on a dry-weight basis. For the purposes of calculation, added bran and germ are not considered refined-grain ingredients. Additional recommendations are also made on labeling whole-grain content in mixed-cereal foods, such as pizza and ready meals, and a need to meet healthy nutrition criteria. This definition allows easy comparison across product categories because it is based on dry weight and strongly encourages a move from generic whole-grain labels to reporting the actual percentage of whole grain in a product. Although this definition is for guidance only, we hope that it will encourage more countries to adopt regulation around the labeling of whole grains and stimulate greater awareness and consumption of whole grains in the general population. © 2017 American Society for Nutrition.

The Effects of Dy Addition on Microstructure and Mechanical Properties of the As-Cast Mg-5Al-3Ca-2Nd Alloys.

PubMed

Son, Hyeon-Taek; Kim, Yong-Ho; Yoo, Hyo-Sang

2018-03-01

The microstructure of the as-cast Mg-5Al-3Ca-2Nd-xDy alloys consists of α-Mg matrix, (Mg, Al)2Ca eutectic phase, Al-Nd and Al-Dy intermetallic compounds. α-Mg matrix morphology was changed from dendritic to equiaxed with the increase Dy addition. And grain size was remarkably refined. As Dy content was increased, yield strength was improved due to the refined grains and the homogeneous distribution of Al-Dy phase.

Grain refinement control in gas-shielded arc welding of aluminum tubing

NASA Technical Reports Server (NTRS)

Iceland, W. F.; Whiffen, E. L.

1974-01-01

When sections are being welded, operator varies pulse rate of power supply and simultaneously monitors signal on oscilloscope until rate is found which produces maximum arc gas voltage. Remainder of welding is performed with power supply set at this pulse rate, producing desired maximum weld puddle agitation and fine uniform weld of grain structure.

The role of grain size and shape in strengthening of dispersion hardened nickel alloys.

NASA Technical Reports Server (NTRS)

Wilcox, B. A.; Clauer, A. H.

1972-01-01

Thermomechanical processing was used to develop various microstructures in Ni, Ni-2ThO2, Ni-20Cr, Ni-20Cr-2ThO2, Ni-20Cr-10W and Ni-20Cr-10W-2ThO2, and the influence of microstructure on room temperature and elevated temperature strength was investigated. The yield strength at 25 C increased with substructure refinement according to the Hall-Petch relation. It was found that substructure refinement was a much more potent means of strengthening at room temperature than was dispersion hardening. At elevated temperature (1093 C), the most important microstructural feature affecting strength of dispersion hardened nickel alloys was the grain aspect ratio, i.e. grain length, L, divided by grain width,l. The yield strength and creep strength increased linearly with increasing L/l.

Effects of grain size on the strength and ductility of Ni sub 3 Al and Ni sub 3 Al + boron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viens, D.V.; Weihs, T.P.; Baker, I.

Tensile and compression experiments have been performed on Ni{sub 3}Al and on Ni{sub 3}Al + B at 77K to 1023K at 1 {times} 10{sup {minus}4}s{sup {minus}1}. At low temperatures yielding occurs discontinuously and the yield strength obeys the relationship {sigma}{sub y} = {sigma}{sub i} + kd{sup {minus}3/4} where {sigma}{sub i} and k are constants. Grain refinement has little effect on the ductility of the binary alloy, but leads to a brittle to ductile transition in the alloy containing boron. At high temperatures, grain refinement weakens the material, owing to grain boundary sliding. Dynamic recrystalization occurs and leads to another brittlemore » to ductile transition upon refining the grains. Under all conditions investigated, fracture occurs intergranularly. An analysis based upon a work-hardening model is given for the d{sup {minus}3/4} dependence of the yield strength at low temperatures.« less

Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

NASA Astrophysics Data System (ADS)

Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

2016-02-01

In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

Retaining {1 0 0} texture from initial columnar grains in 6.5 wt% Si electrical steels

NASA Astrophysics Data System (ADS)

Liang, Ruiyang; Yang, Ping; Mao, Weimin

2017-11-01

6.5 wt% Si electrical steel is a superior soft magnetic material with excellent magnetic properties which highly depends on texture. In this study, based on the heredity of 〈0 0 1〉 orientation in columnar grains, columnar grains are used as the initial material to prepare non-oriented 6.5 wt% Si electrical steel with excellent magnetic properties. EBSD and XRD techniques are adopted to explore the structure and texture evolution during hot rolling, warm rolling, cold rolling and annealing. The results show that, due to the heredity of "structure and texture" from the initial strong {1 0 0} columnar grains, annealed sheet with {1 0 0}〈0 0 1〉 texture had better magnetic properties, which can be used as non-oriented high-silicon electrical steel. Both preferred cube grain nucleation in deformed {1 1 3}〈3 6 1〉 grains in subsurface and coarse {1 0 0}〈0 0 1〉 deformed grains in center layer show the effect of initial columnar grains with {1 0 0} texture.

Molecular dynamics-based refinement and validation for sub-5 Å cryo-electron microscopy maps

PubMed Central

Singharoy, Abhishek; Teo, Ivan; McGreevy, Ryan; Stone, John E; Zhao, Jianhua; Schulten, Klaus

2016-01-01

Two structure determination methods, based on the molecular dynamics flexible fitting (MDFF) paradigm, are presented that resolve sub-5 Å cryo-electron microscopy (EM) maps with either single structures or ensembles of such structures. The methods, denoted cascade MDFF and resolution exchange MDFF, sequentially re-refine a search model against a series of maps of progressively higher resolutions, which ends with the original experimental resolution. Application of sequential re-refinement enables MDFF to achieve a radius of convergence of ~25 Å demonstrated with the accurate modeling of β-galactosidase and TRPV1 proteins at 3.2 Å and 3.4 Å resolution, respectively. The MDFF refinements uniquely offer map-model validation and B-factor determination criteria based on the inherent dynamics of the macromolecules studied, captured by means of local root mean square fluctuations. The MDFF tools described are available to researchers through an easy-to-use and cost-effective cloud computing resource on Amazon Web Services. DOI: http://dx.doi.org/10.7554/eLife.16105.001 PMID:27383269

Using phase information to enhance speckle noise reduction in the ultrasonic NDE of coarse grain materials

NASA Astrophysics Data System (ADS)

Lardner, Timothy; Li, Minghui; Gachagan, Anthony

2014-02-01

Materials with a coarse grain structure are becoming increasingly prevalent in industry due to their resilience to stress and corrosion. These materials are difficult to inspect with ultrasound because reflections from the grains lead to high noise levels which hinder the echoes of interest. Spatially Averaged Sub-Aperture Correlation Imaging (SASACI) is an advanced array beamforming technique that uses the cross-correlation between images from array sub-apertures to generate an image weighting matrix, in order to reduce noise levels. This paper presents a method inspired by SASACI to further improve imaging using phase information to refine focusing and reduce noise. A-scans from adjacent array elements are cross-correlated using both signal amplitude and phase to refine delay laws and minimize phase aberration. The phase-based and amplitude-based corrected images are used as inputs to a two-dimensional cross-correlation algorithm that will output a weighting matrix that can be applied to any conventional image. This approach was validated experimentally using a 5MHz array a coarse grained Inconel 625 step wedge, and compared to the Total Focusing Method (TFM). Initial results have seen SNR improvements of over 20dB compared to TFM, and a resolution that is much higher.

Whole-grain and refined wheat flours show distinct metabolic profiles in rats as assessed by a 1H NMR-based metabonomic approach.

PubMed

Fardet, Anthony; Canlet, Cécile; Gottardi, Gaëlle; Lyan, Bernard; Llorach, Rafaël; Rémésy, Christian; Mazur, André; Paris, Alain; Scalbert, Augustin

2007-04-01

The protection against diabetes and cardiovascular disease provided by whole-grain cereal consumption has been attributed to the fiber and micronutrients present in the bran. But exactly how this occurs remains unclear due to both diversity of bran constituents and the complexity of the metabolic responses to each of these constituents. We investigated the metabolic responses of 2 groups of rats (n = 10/group) fed 2 diets, for 2 wk each, in a crossover design. One diet contained 60 g/100 g whole-grain wheat flour (WGF) and the other contained 60 g/100 g refined wheat flour (RF). Markers of oxidative stress [urinary isoprostanes and malondialdehydes (MDA), plasma ferric-reducing ability of plasma, MDA, and vitamins E and C] and lipid status (liver and plasma triglycerides and cholesterol) were measured. Urine samples collected during the feeding periods and plasma and liver samples collected at the end of experiment were analyzed by (1)H NMR spectroscopy. Metabonomic analyses showed that each group reached a new metabolic balance within 48 h of changing the diet. Urinary excretion of some tricarboxylic acid cycle intermediates, aromatic amino acids, and hippurate was significantly greater in rats fed the WGF diet. Although the diets did not affect conventional lipid and oxidative stress markers, there were decreases in some liver lipids and increases in liver reduced glutathione and betaine as shown by metabonomic analyses. These suggest that the WGF diet improved the redox and lipid status.

Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

DOEpatents

McCallum, R.W.; Branagan, D.J.

1996-01-23

A method of making a permanent magnet is disclosed wherein (1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and (2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties. 33 figs.

Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

DOEpatents

McCallum, R. William; Branagan, Daniel J.

1996-01-23

A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.

The effect of texture and grain size on improving the mechanical properties of Mg-Al-Zn alloys by friction stir processing.

PubMed

Peng, Jinhua; Zhang, Zhen; Liu, Zhao; Li, Yaozu; Guo, Peng; Zhou, Wei; Wu, Yucheng

2018-03-08

Friction stir processing (FSP) was used to achieve grain refinement on Mg-Al-Zn alloys, which also brought in significant texture modification. The different micro-texture characteristics were found to cause irregular micro-hardness distribution in FSPed region. The effects of texture and grain size were investigated by comparative analyses with strongly textured rolling sheet. Grain refinement improved both strength and elongation in condition of a basal texture while such led to an increment in yield stress and a drop in elongation and ultimate stress when the basal texture was modified by FSP.

Recrystallization and grain growth in NiAl

NASA Technical Reports Server (NTRS)

Haff, G. R.; Schulson, E. M.

1982-01-01

Aluminide intermetallics, because of their strength, microstructural stability, and oxidation resistance at elevated temperatures, represent potential structural materials for use in advanced energy conversion systems. This inherent potential of the intermetallics can currently not be realized in connection with the general brittleness of the materials under ambient conditions. It is pointed out, however, that brittleness is not an inherent characteristic. Single crystals are ductile and polycrystals may be, too, if their grains are fine enough. The present investigation is concerned with an approach for reducing material brittleness, taking into account thermal-mechanically induced grain refinement in NiAl, a B2 aluminide which melts at 1638 C and which retains complete order to its melting point. Attention is given to the kinetics of recrystallization and grain growth of warm-worked, nickel-rich material.

Development of Age-Hardening Technology for Ultrafine-Grained Al-Li-Cu Alloys Fabricated by High-Pressure Torsion

NASA Astrophysics Data System (ADS)

Motoshima, Hiroaki; Hirosawa, Shoichi; Lee, Seungwon; Horita, Zenji; Matsuda, Kenji; Terada, Daisuke

The age-hardening behavior and precipitation microstructures with high dislocation density and ultrafine grains have been studied for cold-rolled and severely deformed 2091 Al-Li-Cu alloy. The age-hardenability at 463K was reduced by high-pressure torsion (HPT) due to the accelerated formation of larger 8-AlLi precipitates at grain boundaries, in place of transgranular precipitation of refined δ'-Al3Li particles that are predominantly observable in the no-deformed and 10%-rolled specimens. When aged at 373K, however, it was successfully achieved for the HPT specimen to increase the hardness up to 290HV, the highest level of hardness among conventional wrought aluminum alloys. The corresponding TEM microstructures confirmed that refined δ' particles precipitate within ultrafine grains while keeping the grain size at 206nm. This result suggests that the combined processing of severe plastic deformation with age-hardening technique enables the fabrication of novel aluminum alloys concurrently strengthened by ultrafine-grained and precipitation hardenings.

Associations between Whole-Grain Intake, Psychosocial Variables, and Home Availability among Elementary School Children

ERIC Educational Resources Information Center

Rosen, Renee A.; Burgess-Champoux, Teri L.; Marquart, Len; Reicks, Marla M.

2012-01-01

Objective: Develop, refine, and test psychosocial scales for associations with whole-grain intake. Methods: A cross-sectional survey was conducted in a Minneapolis/St. Paul suburban elementary school with children in fourth through sixth grades (n = 98) and their parents (n = 76). Variables of interest were child whole-grain intake, self-efficacy,…

Total antioxidant content of alternatives to refined sugar.

PubMed

Phillips, Katherine M; Carlsen, Monica H; Blomhoff, Rune

2009-01-01

Oxidative damage is implicated in the etiology of cancer, cardiovascular disease, and other degenerative disorders. Recent nutritional research has focused on the antioxidant potential of foods, while current dietary recommendations are to increase the intake of antioxidant-rich foods rather than supplement specific nutrients. Many alternatives to refined sugar are available, including raw cane sugar, plant saps/syrups (eg, maple syrup, agave nectar), molasses, honey, and fruit sugars (eg, date sugar). Unrefined sweeteners were hypothesized to contain higher levels of antioxidants, similar to the contrast between whole and refined grain products. To compare the total antioxidant content of natural sweeteners as alternatives to refined sugar. The ferric-reducing ability of plasma (FRAP) assay was used to estimate total antioxidant capacity. Major brands of 12 types of sweeteners as well as refined white sugar and corn syrup were sampled from retail outlets in the United States. Substantial differences in total antioxidant content of different sweeteners were found. Refined sugar, corn syrup, and agave nectar contained minimal antioxidant activity (<0.01 mmol FRAP/100 g); raw cane sugar had a higher FRAP (0.1 mmol/100 g). Dark and blackstrap molasses had the highest FRAP (4.6 to 4.9 mmol/100 g), while maple syrup, brown sugar, and honey showed intermediate antioxidant capacity (0.2 to 0.7 mmol FRAP/100 g). Based on an average intake of 130 g/day refined sugars and the antioxidant activity measured in typical diets, substituting alternative sweeteners could increase antioxidant intake an average of 2.6 mmol/day, similar to the amount found in a serving of berries or nuts. Many readily available alternatives to refined sugar offer the potential benefit of antioxidant activity.

TaGS5-3A, a grain size gene selected during wheat improvement for larger kernel and yield.

PubMed

Ma, Lin; Li, Tian; Hao, Chenyang; Wang, Yuquan; Chen, Xinhong; Zhang, Xueyong

2016-05-01

Grain size is a dominant component of grain weight in cereals. Earlier studies have shown that OsGS5 plays a major role in regulating both grain size and weight in rice via promotion of cell division. In this study, we isolated TaGS5 homoeologues in wheat and mapped them on chromosomes 3A, 3B and 3D. Temporal and spatial expression analysis showed that TaGS5 homoeologues were preferentially expressed in young spikes and developing grains. Two alleles of TaGS5-3A, TaGS5-3A-T and TaGS5-3A-G were identified in wheat accessions, and a functional marker was developed to discriminate them. Association analysis revealed that TaGS5-3A-T was significantly correlated with larger grain size and higher thousand kernel weight. Biochemical assays showed that TaGS5-3A-T possesses a higher enzymatic activity than TaGS5-3A-G. Transgenic rice lines overexpressing TaGS5-3A-T also exhibited larger grain size and higher thousand kernel weight than TaGS5-3A-G lines, and the transcript levels of cell cycle-related genes in TaGS5-3A-T lines were higher than those in TaGS5-3A-G lines. Furthermore, systematic evolution analysis in diploid, tetraploid and hexaploid wheat showed that TaGS5-3A underwent strong artificial selection during wheat polyploidization events and the frequency changes of two alleles demonstrated that TaGS5-3A-T was favoured in global modern wheat cultivars. These results suggest that TaGS5-3A is a positive regulator of grain size and its favoured allele TaGS5-3A-T exhibits a larger potential application in wheat high-yield breeding. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Grain refinement and Lattice Imperfections in Commercial Aluminum Alloy Processed by Severe Plastic Deformation

NASA Astrophysics Data System (ADS)

Charfeddine, Saifeddine; Zehani, Karim; Besais, Lotfi; Korchef, Atef

2014-08-01

In the present work, investigations on the microstructure of an aluminum alloy that had been subjected to severe plastic deformation (SPD) by equal channel angular pressing (ECAP), filing and ball milling, were carried out using X-ray diffraction and scanning electron microscopy. SPD leads to lattice distortions, increased dislocation density and an intensive refinement of the microstructure. The refinement and lattice imperfections of the material are greatly affected by the deformation modes and loading performance occurring during SPD. During the milling, the dislocation annihilation increases at higher strains thereby resulting in a smaller crystallite size. After ECAP, the material manifests a strong shear texture and anisotropy of the deformation behavior. Strain anisotropy is less pronounced in filed and ball milled powder particles.

Processing of fine grained AISI 304L austenitic stainless steel by cold rolling and high-temperature short-term annealing

NASA Astrophysics Data System (ADS)

Naghizadeh, Meysam; Mirzadeh, Hamed

2018-05-01

An advanced thermomechanical process based on the formation and reversion of deformation-induced martensite was used to refine the grain size and enhance the hardness of an AISI 304L austenitic stainless steel. Both low and high reversion annealing temperatures and also the repetition of the whole thermomechanical cycle were considered. While a microstructure with average austenite grain size of a few micrometers was achieved based on cold rolling and high-temperature short-term annealing, an extreme grain refinement up to submicrometer regime was obtained by cold rolling followed by low-temperature long-term annealing. However, the required annealing time was found to be much longer, which negates its appropriateness for industrial production. While a magnificent grain refinement was achieved by one pass of the high-temperature thermomechanical process, the reduction in grain size was negligible by the repetition of the whole cycle. It was found that the hardness of the thermomechanically processed material is much higher than that of the as-received material. The results of the present work were shown to be compatible with the general trend of grain size dependence of hardness for AISI 304L stainless steel based on the Hall-Petch relationship. The results were also discussed based on the X-ray evaluation of dislocation density by modified Williamson-Hall plots.

Refining Parameters of the XO-5 Planetary System with High-Precision Transit Photometry

NASA Astrophysics Data System (ADS)

Maciejewski, G.; Seeliger, M.; Adam, Ch.; Raetz, St.; Neuhäuser, R.

2011-03-01

Studies of transiting extrasolar planets provide unique opportunity to get to know the internal structure of those worlds. The transiting exoplanet XO-5 b was found to have an anomalously high Safronov number and surface gravity. Our aim was to refine parameters of this intriguing system and search for signs of transit timing variations. We gathered high-precision light curves for two transits of XO-5 b. Assuming three different limb darkening laws, we found the best-fitting model and redetermined parameters of the system, including planet-to-star radius ratio, impact parameter and central time of transits. Error estimates were derived by the prayer bead method and Monte Carlo simulations. Although system's parameters obtained by us were found to agree with previous studies within one sigma, the planet was found to be notable smaller with the radius of 1.03+0.06-0.05 Jupiter radii. Our results confirm the high Safronov number and surface gravity of the planet. With two new mid-transit times, the ephemeris was refined to BJDTDB=(2454485.66842±0.00028)+(4.1877537±0.000017)E. No significant transit timing variation was detected.

Phase-matching directions, refined Sellmeier equations, and second-order nonlinear coefficient of the infrared Langatate crystal La₃Ga(5.5)Ta(0.5)O₁₄.

PubMed

Boursier, Elodie; Segonds, Patricia; Boulanger, Benoit; Félix, Corinne; Debray, Jérôme; Jegouso, David; Ménaert, Bertrand; Roshchupkin, Dmitry; Shoji, Ichiro

2014-07-01

We directly measured phase-matching directions of second harmonic, sum, and difference frequency generations in the Langatate La₃Ga(5.5)Ta(0.5)O₁₄ (LGT) uniaxial crystal. The simultaneous fit of the data enabled us to refine the Sellmeier equations of the ordinary and extraordinary principal refractive indices over the entire transparency range of the crystal, and to calculate the phase-matching curves and efficiencies of LGT for infrared optical parametric generation.

An Informatics Based Approach to Reduce the Grain Size of Cast Hadfield Steel

NASA Astrophysics Data System (ADS)

Dey, Swati; Pathak, Shankha; Sheoran, Sumit; Kela, Damodar H.; Datta, Shubhabrata

2016-04-01

Materials Informatics concept using computational intelligence based approaches are employed to bring out the significant alloying additions to achieve grain refinement in cast Hadfield steel. Castings of Hadfield steels used for railway crossings, requires fine grained austenitic structure. Maintaining proper grain size of this component is very crucial in order to achieve the desired properties and service life. This work studies the important variables affecting the grain size of such steels which includes the compositional and processing variables. The computational findings and prior knowledge is used to design the alloy, which is subjected to a few trials to validate the findings.

Does Whole Grain Consumption Alter Gut Microbiota and Satiety?

PubMed Central

Cooper, Danielle N.; Martin, Roy J.; Keim, Nancy L.

2015-01-01

This review summarizes recent studies examining whole grain consumption and its effect on gut microbiota and satiety in healthy humans. Studies comparing whole grains to their refined grain counterparts were considered, as were studies comparing different grain types. Possible mechanisms linking microbial metabolism and satiety are described. Clinical trials show that whole grain wheat, maize, and barley alter the human gut microbiota, but these findings are based on a few studies that do not include satiety components, so no functional claims between microbiota and satiety can be made. Ten satiety trials were evaluated and provide evidence that whole oats, barley, and rye can increase satiety, whereas the evidence for whole wheat and maize is not compelling. There are many gaps in the literature; no one clinical trial has examined the effects of whole grains on satiety and gut microbiota together. Once understanding the impact of whole grains on satiety and microbiota is more developed, then particular grains might be used for better appetite control. With this information at hand, healthcare professionals could make individual dietary recommendations that promote satiety and contribute to weight control. PMID:27417768

Effects of whole grains on coronary heart disease risk.

PubMed

Harris, Kristina A; Kris-Etherton, Penny M

2010-11-01

Characterizing which types of carbohydrates, including whole grains, reduce the risk for coronary heart disease (CHD) is challenging. Whole grains are characterized as being high in resistant carbohydrates as compared with refined grains, meaning they typically are high in fiber, nutrients, and bound antioxidants. Whole grain intake consistently has been associated with improved cardiovascular disease outcomes, but also with healthy lifestyles, in large observational studies. Intervention studies that assess the effects of whole grains on biomarkers for CHD have mixed results. Due to the varying nutrient compositions of different whole grains, each could potentially affect CHD risk via different mechanisms. Whole grains high in viscous fiber (oats, barley) decrease serum low-density lipoprotein cholesterol and blood pressure and improve glucose and insulin responses. Grains high in insoluble fiber (wheat) moderately lower glucose and blood pressure but also have a prebiotic effect. Obesity is inversely related to whole grain intake, but intervention studies with whole grains have not produced weight loss. Visceral fat, however, may be affected favorably. Grain processing improves palatability and can have varying effects on nutrition (e.g., the process of milling and grinding flour increases glucose availability and decreases phytochemical content whereas thermal processing increases available antioxidants). Understanding how individual grains, in both natural and processed states, affect CHD risk can inform nutrition recommendations and policies and ultimately benefit public health.

A Food Service Intervention Improves Whole Grain Access at Lunch in Rural Elementary Schools

ERIC Educational Resources Information Center

Cohen, Juliana F. W.; Rimm, Eric B.; Austin, S. Bryn; Hyatt, Raymond R.; Kraak, Vivica I.; Economos, Christina D.

2014-01-01

Background: Whole grain (WG) options are often limited in schools, which may impact rural, low-income students who rely on school meals for a substantial portion of their food intake. This study examined the changes in the availability and quantity of WG and refined grain foods offered in schools participating in the Creating Healthy, Active and…

Whole-grain pasta reduces appetite and meal-induced thermogenesis acutely: a pilot study.

PubMed

Cioffi, Iolanda; Santarpia, Lidia; Vaccaro, Andrea; Iacone, Roberto; Labruna, Giuseppe; Marra, Maurizio; Contaldo, Franco; Kristensen, Mette; Pasanisi, Fabrizio

2016-03-01

In epidemiological studies, the intake of foods rich in dietary fiber is associated with a reduced risk of developing overweight and type 2 diabetes. This work aims to identify acute strategies to regulate appetite and improve glucose control by using different pasta meals. Hence, 4 different isocaloric lunch meals, consisting of (i) refined-grain pasta (RG+T), (ii) whole-grain pasta (WG+T), (iii) lemon juice-supplemented refined-grain pasta (LRG+T), and (iv) refined-grain pasta with legumes (RG+L), were administered to 8 healthy participants in a crossover design. On the test days, participants underwent baseline measurements, including appetite sensation, blood sample, and resting energy expenditure (EE), after which the test lunch was served. Subjective appetite was assessed and a blood sample was taken each hour for 240 min, and postprandial EE was measured for 3 h. In repeated-measures analysis of covariance (ANCOVA), postprandial fullness (p = 0.001) increased and hunger (p = 0.038) decreased. WG+T had a lower EE than did both LGR+T (p = 0.02) and RG+L (p < 0.001). Likewise, meal-induced thermogenesis was lower for WG+T compared with RG+L (58 ± 81 kJ vs 248 ± 188 kJ; p < 0.05). Plasma glucose (p = 0.001) was lower for RG+T, and triacylglycerols (p = 0.02) increased for LRG+T; however, insulin, C-peptide, and ghrelin were comparable in all other meals. In conclusion, our study indicates that acute consumption of whole-grain pasta may promote fullness and reduce hunger, lowering postprandial thermogenesis, and adding lemon juice to the pasta or legumes does not appear to affect appetite. However, none of pasta meal alterations improved the postprandial metabolic profile.

The association of whole grain consumption with incident type 2 diabetes: the Women's Health Initiative Observational Study.

PubMed

Parker, Emily D; Liu, Simin; Van Horn, Linda; Tinker, Leslie F; Shikany, James M; Eaton, Charles B; Margolis, Karen L

2013-06-01

Whole grains may offer protection from diabetes by decreasing energy intake, preventing weight gain, and direct effects on insulin resistance. This study examined associations of whole and refined grains with incident type 2 diabetes (T2D) ascertained by self-reported medication use in a cohort of postmenopausal women. We included 72,215 women free of diabetes at baseline from the Women's Health Initiative Observational Study. Whole grain consumption was categorized as 0, less than 0.5, 0.5 to 1.0, 1.0 to less than 1.5, 1.5 to less than 2.0, and 2.0 or more servings per day. Proportional hazards regression was performed to estimate hazard ratios (HR) and 95% confidence intervals adjusting for potential confounders. There were 3465 cases of incident T2D over median follow-up of 7.9 years. Adjusted for age and energy intake per day, successively increasing categories of whole grain consumption were associated with statistically significant reduced risk of incident T2D (HRs, 1.00, 0.83, 0.73, 0.69, 0.61, and 0.57; P for trend < 0.0001). Results were attenuated after adjustment for confounders and other dietary components. The reduction in risk of T2D was greater among nonsmokers and those who maintained their weight within 5 pounds with higher consumption of whole grains than smokers and women who gained more weight. This large, prospective study found an inverse dose-response relationship between whole grain consumption and incident T2D in postmenopausal women. Copyright © 2013 Elsevier Inc. All rights reserved.

Effect of Cryorolling and Aging on Fatigue Behavior of Ultrafine-grained Al6061

NASA Astrophysics Data System (ADS)

Yadollahpour, M.; Hosseini-Toudeshky, H.; Karimzadeh, F.

2016-05-01

The effects of cryorolling (rolling at liquid nitrogen temperature) and heat treatment on tensile and high-cycle fatigue properties and fatigue crack growth rate of Al6061 alloy have been investigated in the present work. First, the solid solution-treated bulk Al6061 alloy was subjected to cryorolling with 90% total thickness reduction and subsequent short annealing at 205°C for 5 min and peak aging at 148°C for 39 h to achieve grain refinement and simultaneous improvement of the strength and ductility. Then, hardness measurements, tensile tests, fatigue life, and fatigue crack growth rate tests including fractography analyses using scanning electron microscopy were performed on bulk Al6061 alloy, cryorolled (CR), and cryorolled material followed by peak aging (PA). The PA specimen showed improved yield strength by 24%, ultimate tensile strength by 20%, and ductility by 12% as compared with the bulk Al6061 alloy. It is shown that the fatigue strength of both CR and PA specimens under a high-cycle fatigue regime are larger than that of the bulk Al6061 alloy. Also, fatigue crack growth rates of the CR and PA specimens show significant enhancement in fatigue crack growth resistances as compared with the bulk Al6061 alloy, as a result of grain refinement.

Nano/ultrafine grained austenitic stainless steel through the formation and reversion of deformation-induced martensite: Mechanisms, microstructures, mechanical properties, and TRIP effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shirdel, M., E-mail: mshirdel1989@ut.ac.ir; Mirzadeh, H., E-mail: hmirzadeh@ut.ac.ir; Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran

A comprehensive study was carried out on the strain-induced martensitic transformation, its reversion to austenite, the resultant grain refinement, and the enhancement of strength and strain-hardening ability through the transformation-induced plasticity (TRIP) effect in a commercial austenitic 304L stainless steel with emphasis on the mechanisms and the microstructural evolution. A straightforward magnetic measurement device, which is based on the measurement of the saturation magnetization, for evaluating the amount of strain-induced martensite after cold rolling and reversion annealing in metastable austenitic stainless steels was used, which its results were in good consistency with those of the X-ray diffraction (XRD) method. Amore » new parameter called the effective reduction in thickness was introduced, which corresponds to the reasonable upper bound on the obtainable martensite fraction based on the saturation in the martensitic transformation. By means of thermodynamics calculations, the reversion mechanisms were estimated and subsequently validated by experimental results. The signs of thermal martensitic transformation at cooling stage after reversion at 850 °C were found, which was attributed to the rise in the martensite start temperature due to the carbide precipitation. After the reversion treatment, the average grain sizes were around 500 nm and the nanometric grains of the size of ~ 65 nm were also detected. The intense grain refinement led to the enhanced mechanical properties and observation of the change in the work-hardening capacity and TRIP effect behavior. A practical map as a guidance for grain refining and characterizing the stability against grain growth was proposed, which shows the limitation of the reversion mechanism for refinement of grain size. - Graphical abstract: Display Omitted - Highlights: • Nano/ultrafine grained austenitic stainless steel through martensite treatment • A parameter descriptive of a reasonable upper

Carpel size, grain filling, and morphology determine individual grain weight in wheat

PubMed Central

Xie, Quan; Mayes, Sean; Sparkes, Debbie L.

2015-01-01

Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)×spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulation, and grain dimensions interacted strongly with each other. Furthermore, larger carpels, a faster grain filling rate, earlier and longer grain filling, more grain water, faster grain water absorption and loss rates, and larger grain dimensions were associated with higher grain weight. Frequent quantitative trait locus (QTL) coincidences between these traits were observed, particularly those on chromosomes 2A, 3B, 4A, 5A, 5DL, and 7B, each of which harboured 16−49 QTLs associated with >12 traits. Analysis of the allelic effects of coincident QTLs confirmed their physiological relationships, indicating that the complex but orderly grain filling processes result mainly from pleiotropy or the tight linkages of functionally related genes. After grain filling, distal grains within spikelets were smaller than basal grains, primarily due to later grain filling and a slower initial grain filling rate, followed by synchronous maturation among different grains. Distal grain weight was improved by increased assimilate availability from anthesis. These findings provide deeper insight into grain weight determination in wheat, and the high level of QTL coincidences allows simultaneous improvement of multiple grain filling traits in breeding. PMID:26246614

On the kinetics of transgranular particle embrittlement during simulated carburizing in steel containing grain-refining additions of aluminum and niobium plus aluminum

DOE PAGES

Leap, Michael Jerald

2017-08-31

Here, the kinetics of toughness degradation resulting from transgranular particle embrittlement are evaluated as a function of composition and processing history for simulated carburizing operations in air-melt steel containing grain-refining additions of aluminum and aluminum plus niobium. The kinetics of particle embrittlement are inherently linked to the ripening of AlN precipitates after extended austenitization in steel containing carbon contents representative of both the case and core of a carburized component. Embrittlement in steel containing AlN occurs with an activation energy similar to the value for aluminum diffusion in austenite, although an AlN volume fraction effect on the embrittlement kinetics ismore » manifested as decreases in activation energy with decreases in the [Al]/[N] ratio of steel. In contrast, the presence of niobium substantially retards the kinetics of particle embrittlement in steel containing 120–200 ppm N. Observations of AlN precipitates coated with Nb(C,N) indicate that the decreases in embrittlement kinetics are related to a reduction in the potential for AlN ripening during austenitization.« less

On the kinetics of transgranular particle embrittlement during simulated carburizing in steel containing grain-refining additions of aluminum and niobium plus aluminum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leap, Michael Jerald

Here, the kinetics of toughness degradation resulting from transgranular particle embrittlement are evaluated as a function of composition and processing history for simulated carburizing operations in air-melt steel containing grain-refining additions of aluminum and aluminum plus niobium. The kinetics of particle embrittlement are inherently linked to the ripening of AlN precipitates after extended austenitization in steel containing carbon contents representative of both the case and core of a carburized component. Embrittlement in steel containing AlN occurs with an activation energy similar to the value for aluminum diffusion in austenite, although an AlN volume fraction effect on the embrittlement kinetics ismore » manifested as decreases in activation energy with decreases in the [Al]/[N] ratio of steel. In contrast, the presence of niobium substantially retards the kinetics of particle embrittlement in steel containing 120–200 ppm N. Observations of AlN precipitates coated with Nb(C,N) indicate that the decreases in embrittlement kinetics are related to a reduction in the potential for AlN ripening during austenitization.« less

Strength of Rocks Affected by Deformation Enhanced Grain Growth

NASA Astrophysics Data System (ADS)

Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

2005-12-01

One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

Prediction of the Grain-Microstructure Evolution Within a Friction Stir Welding (FSW) Joint via the Use of the Monte Carlo Simulation Method

NASA Astrophysics Data System (ADS)

Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Avuthu, V.; Galgalikar, R.; Zhang, Z.

2015-09-01

A thermo-mechanical finite element analysis of the friction stir welding (FSW) process is carried out and the evolution of the material state (e.g., temperature, the extent of plastic deformation, etc.) monitored. Subsequently, the finite-element results are used as input to a Monte-Carlo simulation algorithm in order to predict the evolution of the grain microstructure within different weld zones, during the FSW process and the subsequent cooling of the material within the weld to room temperature. To help delineate different weld zones, (a) temperature and deformation fields during the welding process, and during the subsequent cooling, are monitored; and (b) competition between the grain growth (driven by the reduction in the total grain-boundary surface area) and dynamic-recrystallization grain refinement (driven by the replacement of highly deformed material with an effectively "dislocation-free" material) is simulated. The results obtained clearly revealed that different weld zones form as a result of different outcomes of the competition between the grain growth and grain refinement processes.

Carpel size, grain filling, and morphology determine individual grain weight in wheat.

PubMed

Xie, Quan; Mayes, Sean; Sparkes, Debbie L

2015-11-01

Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)×spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulation, and grain dimensions interacted strongly with each other. Furthermore, larger carpels, a faster grain filling rate, earlier and longer grain filling, more grain water, faster grain water absorption and loss rates, and larger grain dimensions were associated with higher grain weight. Frequent quantitative trait locus (QTL) coincidences between these traits were observed, particularly those on chromosomes 2A, 3B, 4A, 5A, 5DL, and 7B, each of which harboured 16-49 QTLs associated with >12 traits. Analysis of the allelic effects of coincident QTLs confirmed their physiological relationships, indicating that the complex but orderly grain filling processes result mainly from pleiotropy or the tight linkages of functionally related genes. After grain filling, distal grains within spikelets were smaller than basal grains, primarily due to later grain filling and a slower initial grain filling rate, followed by synchronous maturation among different grains. Distal grain weight was improved by increased assimilate availability from anthesis. These findings provide deeper insight into grain weight determination in wheat, and the high level of QTL coincidences allows simultaneous improvement of multiple grain filling traits in breeding. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Structure-based coarse-graining for inhomogeneous liquid polymer systems.

PubMed

Fukuda, Motoo; Zhang, Hedong; Ishiguro, Takahiro; Fukuzawa, Kenji; Itoh, Shintaro

2013-08-07

The iterative Boltzmann inversion (IBI) method is used to derive interaction potentials for coarse-grained (CG) systems by matching structural properties of a reference atomistic system. However, because it depends on such thermodynamic conditions as density and pressure of the reference system, the derived CG nonbonded potential is probably not applicable to inhomogeneous systems containing different density regimes. In this paper, we propose a structure-based coarse-graining scheme to devise CG nonbonded potentials that are applicable to different density bulk systems and inhomogeneous systems with interfaces. Similar to the IBI, the radial distribution function (RDF) of a reference atomistic bulk system is used for iteratively refining the CG nonbonded potential. In contrast to the IBI, however, our scheme employs an appropriately estimated initial guess and a small amount of refinement to suppress transfer of the many-body interaction effects included in the reference RDF into the CG nonbonded potential. To demonstrate the application of our approach to inhomogeneous systems, we perform coarse-graining for a liquid perfluoropolyether (PFPE) film coated on a carbon surface. The constructed CG PFPE model favorably reproduces structural and density distribution functions, not only for bulk systems, but also at the liquid-vacuum and liquid-solid interfaces, demonstrating that our CG scheme offers an easy and practical way to accurately determine nonbonded potentials for inhomogeneous systems.

A whole-grain cereal-based diet lowers postprandial plasma insulin and triglyceride levels in individuals with metabolic syndrome.

PubMed

Giacco, R; Costabile, G; Della Pepa, G; Anniballi, G; Griffo, E; Mangione, A; Cipriano, P; Viscovo, D; Clemente, G; Landberg, R; Pacini, G; Rivellese, A A; Riccardi, G

2014-08-01

Until recently, very few intervention studies have investigated the effects of whole-grain cereals on postprandial glucose, insulin and lipid metabolism, and the existing studies have provided mixed results. The objective of this study was to evaluate the effects of a 12-week intervention with either a whole-grain-based or a refined cereal-based diet on postprandial glucose, insulin and lipid metabolism in individuals with metabolic syndrome. Sixty-one men and women age range 40-65 years, with the metabolic syndrome were recruited to participate in this study using a parallel group design. After a 4-week run-in period, participants were randomly assigned to a 12-week diet based on whole-grain products (whole-grain group) or refined cereal products (control group). Blood samples were taken at the beginning and end of the intervention, both fasting and 3 h after a lunch, to measure biochemical parameters. Generalized linear model (GLM) was used for between-group comparisons. Overall, 26 participants in the control group and 28 in the whole-grain group completed the dietary intervention. Drop-outs (five in the control and two in the whole-grain group) did not affect randomization. After 12 weeks, postprandial insulin and triglyceride responses (evaluated as average change 2 and 3 h after the meal, respectively) decreased by 29% and 43%, respectively, in the whole-grain group compared to the run-in period. Postprandial insulin and triglyceride responses were significantly lower at the end of the intervention in the whole-grain group compared to the control group (p = 0.04 and p = 0.05; respectively) whereas there was no change in postprandial response of glucose and other parameters evaluated. A twelve week whole-grain cereal-based diet, compared to refined cereals, reduced postprandial insulin and triglycerides responses. This finding may have implications for type 2 diabetes risk and cardiovascular disease. Copyright © 2014 Elsevier B.V. All rights reserved.

Whole Grains and Fiber

MedlinePlus

... or another cereal is a grain product. Bread, pasta, oatmeal and grits are all grain products. There ... whole-grain cereal, brown rice, or whole-wheat pasta 5 whole-grain crackers 3 cups unsalted, air- ...

Effects of grain size on the quasi-static mechanical properties of ultrafine-grained and nanocrystalline tantalum

NASA Astrophysics Data System (ADS)

Ligda, Jonathan Paul

The increase in strength due to the Hall-Petch effect, reduced strain hardening capacity, a reduced ductility, and changes in deformation mechanisms are all effects of reducing grain size (d) into the ultrafine-grained (UFG, 100 < d < 1000 nm) and nanocrystalline (NC, d<100 nm) state. However, most of the studies on the mechanical behavior of UFG/NC metals have been on face-centered cubic (FCC) metals. Of the few reports on UFG/NC body-centered cubic (BCC) metals, the interest is related to their increase in strength and reduced strain rate sensitivity. This combination increases their propensity to deform via adiabatic shear bands (ASBs) at high strain rates, which is a desired response for materials being considered as a possible replacement for depleted uranium in kinetic energy penetrators. However, an ideal replacement material must also plastically deform in tension under quasi-static rates to survive initial launch conditions. This raises the question: if the material forms ASBs at dynamic rates, will it also form shear bands at quasi-static isothermal rates? As well as, is there a specific grain size for a material that will plastically deform in tension at quasi-static rates but form adiabatic shear bands at dynamic rates? Using high pressure torsion, a polycrystalline bulk tantalum disk was refined into the UFG/NC regime. Using microscale mechanical testing techniques, such as nanoindentation, microcompression, and microtension, it is possible to isolate locations with a homogeneous grain size within the disk. Pillars are compressed using a nanoindenter with a flat punch tip, while "dog-bone" specimens were pulled in tension using a custom built in-situ tension stage within a scanning electron microscope (SEM). The observed mechanical behavior is related to the microstructure by using transmission electron microscopy (TEM) on the as-processed material and tested specimens. Synchrotron X-ray based texture analysis was also conducted on the disk to

Fabrication of MEMS components using ultrafine-grained aluminium alloys

NASA Astrophysics Data System (ADS)

Qiao, Xiao Guang; Gao, Nong; Moktadir, Zakaria; Kraft, Michael; Starink, Marco J.

2010-04-01

A novel process for the fabrication of a microelectromechanical systems (MEMS) metallic component with features smaller than 10 µm and high thermal conductivity was investigated. This may be applied to new or improved microscale components, such as (micro-) heat exchangers. In the first stage of processing, equal channel angular pressing (ECAP) was employed to refine the grain size of commercial purity aluminium (Al-1050) to the ultrafine-grained (UFG) material. Embossing was conducted using a micro silicon mould fabricated by deep reactive ion etching (DRIE). Both cold embossing and hot embossing were performed on the coarse-grained and UFG Al-1050. Cold embossing on UFG Al-1050 led to a partially transferred pattern from the micro silicon mould and high failure rate of the mould. Hot embossing on UFG Al-1050 provided a smooth embossed surface with a fully transferred pattern and a low failure rate of the mould, while hot embossing on the coarse-grained Al-1050 resulted in a rougher surface with shear bands.

K-Means Subject Matter Expert Refined Topic Model Methodology

DTIC Science & Technology

2017-01-01

Refined Topic Model Methodology Topic Model Estimation via K-Means U.S. Army TRADOC Analysis Center-Monterey 700 Dyer Road...January 2017 K-means Subject Matter Expert Refined Topic Model Methodology Topic Model Estimation via K-Means Theodore T. Allen, Ph.D. Zhenhuan...Matter Expert Refined Topic Model Methodology Topic Model Estimation via K-means 5a. CONTRACT NUMBER W9124N-15-P-0022 5b. GRANT NUMBER 5c

Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

NASA Astrophysics Data System (ADS)

Guo, Hong-Yan; Xia, Min; Wu, Zheng-Tao; Chan, Lap-Chung; Dai, Yong; Wang, Kun; Yan, Qing-Zhi; He, Man-Chao; Ge, Chang-Chun; Lu, Jian

2016-11-01

A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3-5%. Dislocation density in the SMATed W nanograins was found to be 5 × 1012 cm-2. The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about -881 MPa and -234 MPa in y direction, and -872 MPa and -879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

Rietveld-refinement and optical study of the Fe doped ZnO thin film by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kumar, Arun; Dhiman, Pooja; Singh, M.

2017-05-01

Fe Doped ZnO Dilute Magnetic Semiconductor thin film prepared by RF magnetron sputtering on glass substrate and Influence of 3% Fe-doping on structural and Optical properties has been studied. The Rietveld-refinement analysis shows that Fe doping has a significant effect on crystalline structure, grain size and strain in the thin film. Two dimensional and three-dimensional atom probe tomography of the thin film shows that Fe ions are randomly distributed which is supported by Xray Diffraction (XRD). Fe-doping is found to effectively modify the band gap energy up to 3.5 eV.

Ultra-fine grained microstructure of metastable beta Ti-15Mo alloy and its effects on the phase transformations

NASA Astrophysics Data System (ADS)

Václavová, K.; Stráský, J.; Zháňal, P.; Veselý, J.; Polyakova, V.; Semenova, I.; Janeček, M.

2017-05-01

Processing of metastable titanium alloys by severe plastic deformation provides an opportunity to achieve exceptional grain refinement, to enhance the strength and to affect phase transformations occurring during thermal treatment. The main aim of this study is to investigate the microstructure of ultra-fine grained (UFG) material and effect of microstructural changes on phase transformations in metastable β-Ti alloy Ti-15Mo. Metastable β-Ti alloys are currently the most studied Ti-based materials with prospective use in medicine. Ti-15Mo alloy after solution treatment contains metastable β-phase. Metastable ω-phase and stable α-phase particles are formed upon annealing,. Solution treated Ti-15Mo alloy was deformed by high pressure torsion (HPT) at room temperature. Severely deformed structure after HPT with grain size of ~200 nm was studied by transmission electron microscopy. In-situ electrical resistance measurements showed significant changes in undergoing phase transformations when compared to coarse-grained (CG) material. Scanning electron microscopy revealed heterogeneous precipitation of α-particles at grain boundaries (GB). Due to the high density of GBs in UFG structure, these precipitates are very fine and equiaxed. The study demonstrates that SPD is capable of enhancing mechanical properties due to grain refinement and via affecting precipitation processes in metastable β-Ti alloys.

Effects of Grain Orientation on Cu6Sn5 Growth Behavior in Cu6Sn5-Reinforced Composite Solder Joints During Electromigration

NASA Astrophysics Data System (ADS)

Han, Jing; Wang, Yan; Tan, Shihai; Guo, Fu

2018-02-01

Electromigration is a major reliability problem in composite solder joints. Due to the anisotropy of the β-Sn crystal structure, the Sn grain orientations present in the solder matrix dominate the principal failure mechanism in solder joints under electric current stressing. In this work, the Cu6Sn5 growth behavior in Cu6Sn5-reinforced composite solder joints with three different Sn grain orientations was investigated at current density of 104 A/cm2 at room temperature. Micron-sized Cu particles were added to Sn-3.5Ag solder at 2% volume fraction using an in situ method. After current stressing for 528 h, the polarity effect in the composite solder joint was greatest for an angle ( θ) between the c-axis and electron flow direction of 30°, resulting in higher growth rate of Cu6Sn5 in the solder matrix compared with composite solder joints with θ of 60° or 90°. There were no noticeable changes in the composite solder joint with θ of 90°. The growth behavior of Cu6Sn5, Cu atomic motion, and Cu diffusivity in the composite solder joints with different Sn grain orientations were analyzed in detail.

Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel.

PubMed

Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

2012-06-01

A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength-toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation.

Relationship between morphologies and orientations of Cu{sub 6}Sn{sub 5} grains in Sn3.0Ag0.5Cu solder joints on different Cu pads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Yanhong, E-mail: tianyh@hit.edu.cn; Zhang, Rui; Hang, Chunjin

2014-02-15

The morphologies and orientations of Cu{sub 6}Sn{sub 5} intermetallic compounds in the Sn3.0Ag0.5Cu solder joints both on polycrystalline and single crystal Cu pads under different peak reflow temperatures and times above liquids were investigated. The relationship between Cu{sub 6}Sn{sub 5} grain orientations and morphologies was clarified. At the interface of Sn3.0Ag0.5Cu/polycrystalline Cu pad, scalloped Cu{sub 6}Sn{sub 5} intermetallic compounds formed at 250 °C and roof shape Cu{sub 6}Sn{sub 5} formed at 300 °C. Both scalloped Cu{sub 6}Sn{sub 5} and roof shape Cu{sub 6}Sn{sub 5} had a preferred orientation of (0001) plane being parallel to polycrystalline Cu pad surface. Besides, themore » percentage of large angle grain boundaries increased as the peak reflow temperature rose. At the interface of Sn3.0Ag0.5Cu/(111) single crystal Cu pad, the Cu{sub 6}Sn{sub 5} intermetallic compounds were mainly scallop-type at 250 °C and were prism type at 300 °C. The prismatic Cu{sub 6}Sn{sub 5} grains grew along the three preferred directions with the inter-angles of 60° on (111) single crystal Cu pad while along two perpendicular directions on (100) single crystal Cu pad. The orientation relationship between Cu{sub 6}Sn{sub 5} grains and the single crystal Cu pads was investigated by electron backscatter diffraction technology. In addition, two types of hollowed Cu{sub 6}Sn{sub 5} intermetallic compounds were found inside the joints of polycrystalline Cu pads. The long hexagonal Cu{sub 6}Sn{sub 5} strips were observed in the joints reflowing at 250 °C while the hollowed Cu{sub 6}Sn{sub 5} strips with the ‘▪’ shape cross-sections appeared at 300 °C, which was attributed to the different grain growth rates of different Cu{sub 6}Sn{sub 5} crystal faces. - Highlights: • The orientation of interfacial Cu{sub 6}Sn{sub 5} grains was obtained by EBSD technology. • Two types of hollowed Cu{sub 6}Sn{sub 5} strips were found at different temperatures. • The

Effects of grain size on the corrosion resistance of pure magnesium by cooling rate-controlled solidification

NASA Astrophysics Data System (ADS)

Liu, Yichi; Liu, Debao; You, Chen; Chen, Minfang

2015-09-01

The aim of this study was to investigate the effect of grain size on the corrosion resistance of pure magnesium developed for biomedical applications. High-purity magnesium samples with different grain size were prepared by the cooling rate-controlled solidification. Electrochemical and immersion tests were employed to measure the corrosion resistance of pure magnesium with different grain size. The electrochemical polarization curves indicated that the corrosion susceptibility increased as the grain size decrease. However, the electrochemical impedance spectroscopy (EIS) and immersion tests indicated that the corrosion resistance of pure magnesium is improved as the grain size decreases. The improvement in the corrosion resistance is attributed to refine grain can produce more uniform and density film on the surface of sample.

Biomechanical properties of wheat grains: the implications on milling.

PubMed

Hourston, James E; Ignatz, Michael; Reith, Martin; Leubner-Metzger, Gerhard; Steinbrecher, Tina

2017-01-01

Millennia of continuous innovation have driven ever increasing efficiency in the milling process. Mechanically characterizing wheat grains and discerning the structure and function of the wheat bran layers can contribute to continuing innovation. We present novel shear force and puncture force testing regimes to characterize different wheat grain cultivars. The forces endured by wheat grains during the milling process can be quantified, enabling us to measure the impact of commonly applied grain pretreatments, such as microwave heating, extended tempering, enzyme and hormone treatments on grains of different 'hardness'. Using these methods, we demonstrate the importance of short tempering phases prior to milling and identify ways in which our methods can detect differences in the maximum force, energy and breaking behaviours of hard and soft grain types. We also demonstrate for the first time, endosperm weakening in wheat, through hormone stratification on single bran layers. The modern milling process is highly refined, meaning that small, cultivar specific, adjustments can result in large increases in downstream profits. We believe that methods such as these, which enable rapid testing of milling pretreatments and material properties can help to drive an innovation process that has been core to our industrial efforts since prehistory. © 2017 The Authors.

Biomechanical properties of wheat grains: the implications on milling

PubMed Central

Reith, Martin

2017-01-01

Millennia of continuous innovation have driven ever increasing efficiency in the milling process. Mechanically characterizing wheat grains and discerning the structure and function of the wheat bran layers can contribute to continuing innovation. We present novel shear force and puncture force testing regimes to characterize different wheat grain cultivars. The forces endured by wheat grains during the milling process can be quantified, enabling us to measure the impact of commonly applied grain pretreatments, such as microwave heating, extended tempering, enzyme and hormone treatments on grains of different ‘hardness’. Using these methods, we demonstrate the importance of short tempering phases prior to milling and identify ways in which our methods can detect differences in the maximum force, energy and breaking behaviours of hard and soft grain types. We also demonstrate for the first time, endosperm weakening in wheat, through hormone stratification on single bran layers. The modern milling process is highly refined, meaning that small, cultivar specific, adjustments can result in large increases in downstream profits. We believe that methods such as these, which enable rapid testing of milling pretreatments and material properties can help to drive an innovation process that has been core to our industrial efforts since prehistory. PMID:28100826

Rietveld refinement of the crystal structures of Rb2 XSi5O12 (X = Ni, Mn).

PubMed

Bell, Anthony M T; Henderson, C Michael B

2016-02-01

The synthetic leucite silicate framework mineral analogues Rb2 XSi5O12 {X = Ni [dirubidium nickel(II) penta-silicate] and Mn [dirubidium manganese(II) penta-silicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetra-hedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb(+) cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetra-hedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni-O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder.

Rietveld refinement of the crystal structures of Rb2 XSi5O12 (X = Ni, Mn)

PubMed Central

Bell, Anthony M. T.; Henderson, C. Michael B.

2016-01-01

The synthetic leucite silicate framework mineral analogues Rb2 XSi5O12 {X = Ni [dirubidium nickel(II) penta­silicate] and Mn [dirubidium manganese(II) penta­silicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetra­hedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb+ cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetra­hedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni—O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder. PMID:26958399

Grain Handling and Storage.

ERIC Educational Resources Information Center

Harris, Troy G.; Minor, John

This text for a secondary- or postecondary-level course in grain handling and storage contains ten chapters. Chapter titles are (1) Introduction to Grain Handling and Storage, (2) Elevator Safety, (3) Grain Grading and Seed Identification, (4) Moisture Control, (5) Insect and Rodent Control, (6) Grain Inventory Control, (7) Elevator Maintenance,…

Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel

PubMed Central

Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

2012-01-01

A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength–toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation. PMID:27877493

Mechanical Properties and Fracture Behaviors of the As-Extruded Mg-5Al-3Ca Alloys Containing Yttrium at Elevated Temperature.

PubMed

Son, Hyeon-Taek; Kim, Yong-Ho; Kim, Taek-Soo; Lee, Seong-Hee

2016-02-01

Effects of yttrium (Y) addition on mechanical properties and fracture behaviors of the as-extruded Mg-Al-Ca based alloys at elevated temperature were investigated by a tensile test. After hot extrusion, the average grain size was refined by Y addition and eutectic phases were broken down into fine particles. Y addition to Mg-5Al-3Ca based alloy resulted in the improvement of strength and ductility at elevated temperature due to fine grain and suppression of grain growth by formation of thermally stable Al2Y intermetallic compound.

Microstructure and properties of ultrafine grain nickel 200 after hydrostatic extrusion processes

NASA Astrophysics Data System (ADS)

Sitek, R.; Krajewski, C.; Kamiński, J.; Spychalski, M.; Garbacz, H.; Pachla, W.; Kurzydłowski, K. J.

2012-09-01

This paper presents the results of the studies of the structure and properties of ultrafine grained nickel 200 obtained by hydrostatic extrusion processes. Microstructure was characterized by means of optical microscopy and electron transmission microscopy. Corrosion resistance was studied by impedance and potentiodynamic methods using an AutoLab PGSTAT 100 potentiostat in 0.1 M Na2SO4 solution and in acidified (by addition of H2SO4) 0.1 M NaCl solution at pH = 4.2 at room temperature. Microhardness tests were also performed. The results showed that hydrostatic extrusion produces a heterogeneous, ultrafine-grained microstructure in nickel 200. The corrosive resistance tests showed that the grain refinement by hydrostatic extrusion is accompanied by a decreased corrosive resistance of nickel 200.

Influence of Pulsed Current on Superplasticity of Fine Grained 1420 Al-Li Alloy

NASA Astrophysics Data System (ADS)

Zhang, Yanling; Hou, Hongliang; Bi, Jing; Wang, Yaoqi

2018-01-01

The effects of an externally applied electropulse on the superplastic deformation behavior and microstructure of 1420 Al-Li alloy were studied. The flow stress of superplastic deformation was reduced by the high-density electropulse while the elongation was increased. The optimal electrical parameters for superplastic deformation were 192A/mm2 of current density, 150Hz of frequency and 30s of duration at 480°C and 0.001s-1. The elongation raised by 68% compared to that without electropulse. Furthermore, the grain was refined and the average grain size was reduced after superplastic deformation with the optimal electropulse. It is noted that the electropulse promoted the recrystallization and restrained the grain growth.

Intergranular corrosion in AA5XXX aluminum alloys with discontinuous precipitation at the grain boundaries

NASA Astrophysics Data System (ADS)

Bumiller, Elissa

The US Navy currently uses AA5xxx aluminum alloys for structures exposed to a marine environment. These alloys demonstrate excellent corrosion resistance over other aluminum alloys (e.g., AA2xxx or AA7xxx) in this environment, filling a niche in the marine structures market when requiring a light-weight alternative to steel. However, these alloys are susceptible to localized corrosion; more specifically, intergranular corrosion (IGC) is of concern. IGC of AA5xxx alloys due to the precipitation of beta phase on the grain boundaries is a well-established phenomenon referred to as sensitization. At high degrees of sensitization, the IGC path is a continuous anodic path of beta phase particles. At lower degrees of sensitization, the beta phase coverage at the grain boundaries is not continuous. The traditional ranges of susceptibility to IGC as defined by ASTM B928 are in question due to recent studies. These studies showed that even at mid range degrees of sensitization where the beta phase is no longer continuous, IGC may still occur. Previous thoughts on IGC of these alloy systems were founded on the idea that once the grain boundary precipitate became discontinuous the susceptibility to IGC was greatly reduced. Additionally, IGC susceptibility has been defined metallurgically by compositional gradients at the grain boundaries. However, AA5xxx alloys show no compositional gradients at the grain boundaries, yet are still susceptible to IGC. The goal of this work is to establish criteria necessary for IGC to occur given no continuous beta phase path and no compositional gradient at the grain boundaries. IGC performance of the bulk alloy system AA5083 has been studied along with the primary phases present in the IGC system: alpha and beta phases using electrochemistry and modeling as the primary tools. Numerical modeling supports that at steady-state the fissure tip is likely saturated with Mg in excess of the 4% dissolved in the matrix. By combining these results

Whole Grains Contribute Only a Small Proportion of Dietary Fiber to the U.S. Diet.

PubMed

Kranz, Sibylle; Dodd, Kevin W; Juan, Wen Yen; Johnson, LuAnn K; Jahns, Lisa

2017-02-17

Dietary fiber (DF), found in whole fruits, vegetables, and whole grains (WG), is considered a nutrient of concern in the US diet and increased consumption is recommended. The present study was designed to highlight this critical importance of the difference between WG, high-fiber WG, and sources of fiber that are not from WG. The study is based on the two-day diets reported consumed by the nationally representative sample of Americans participating in What We Eat In America, the dietary component of the National Health and Nutrition Examination Survey from 2003-2010. Foods consumed were classified into tertiles of DF and WG and the contribution of fiber by differing levels of WG content were examined. Foods containing high amounts of WG and DF only contributed about 7% of total fiber intake. Overall, grain-based foods contributed 54.5% of all DF consumed. Approximately 39% of DF came from grain foods that contained no WG, rather these foods contained refined grains, which contain only small amounts of DF but are consumed in large quantities. All WG-containing foods combined contributed a total of 15.3% of DF in the American diet. Thus, public health messaging needs to be changed to specifically encourage consumption of WG foods with high levels of DF to address both recommendations.

Molecular dynamics force-field refinement against quasi-elastic neutron scattering data

DOE PAGES

Borreguero Calvo, Jose M.; Lynch, Vickie E.

2015-11-23

Quasi-elastic neutron scattering (QENS) is one of the experimental techniques of choice for probing the dynamics at length and time scales that are also in the realm of full-atom molecular dynamics (MD) simulations. This overlap enables extension of current fitting methods that use time-independent equilibrium measurements to new methods fitting against dynamics data. We present an algorithm that fits simulation-derived incoherent dynamical structure factors against QENS data probing the diffusive dynamics of the system. We showcase the difficulties inherent to this type of fitting problem, namely, the disparity between simulation and experiment environment, as well as limitations in the simulationmore » due to incomplete sampling of phase space. We discuss a methodology to overcome these difficulties and apply it to a set of full-atom MD simulations for the purpose of refining the force-field parameter governing the activation energy of methyl rotation in the octa-methyl polyhedral oligomeric silsesquioxane molecule. Our optimal simulated activation energy agrees with the experimentally derived value up to a 5% difference, well within experimental error. We believe the method will find applicability to other types of diffusive motions and other representation of the systems such as coarse-grain models where empirical fitting is essential. In addition, the refinement method can be extended to the coherent dynamic structure factor with no additional effort.« less

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

NASA Astrophysics Data System (ADS)

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher; Li, Shimin; Apelian, Diran; Shyam, Amit; Allen Haynes, J.; Rodriguez, Andres F.

2018-06-01

The hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: "V"-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on the variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

DOE PAGES

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher; ...

2018-02-16

Here, the hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: “V”-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on themore » variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.« less

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher

Here, the hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: “V”-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on themore » variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.« less

Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 piezoelectric materials

PubMed Central

Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; Yan, Yongke; Li, Jiefang; Viehland, Dwight; Priya, Shashank

2015-01-01

We synthesized grain-oriented lead-free piezoelectric materials in (K0.5Bi0.5TiO3-BaTiO3-xNa0.5Bi0.5TiO3 (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d33 ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectric materials. PMID:25716551

Microstructure refinement of cold-sprayed copper investigated by electron channeling contrast imaging.

PubMed

Zhang, Yinyin; Brodusch, Nicolas; Descartes, Sylvie; Chromik, Richard R; Gauvin, Raynald

2014-10-01

The electron channeling contrast imaging technique was used to investigate the microstructure of copper coatings fabricated by cold gas dynamic spray. The high velocity impact characteristics for cold spray led to the formation of many substructures, such as high density dislocation walls, dislocation cells, deformation twins, and ultrafine equiaxed subgrains/grains. A schematic model is proposed to explain structure refinement of Cu during cold spray, where an emphasis is placed on the role of dislocation configurations and twinning.

Grain Boundary Complexions

DTIC Science & Technology

2014-05-01

for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE MAY 2014 2. REPORT...TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Grain boundary complexions 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...specific adsorption sites of rare- earth elements at IGF/grain inter- faces [142–144], and the viscosity [145] and mechanical strength [146–148] of

In vitro and in vivo studies of biodegradable fine grained AZ31 magnesium alloy produced by equal channel angular pressing.

PubMed

Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh; Devi Prasad, V; Raghunath, M

2016-02-01

The objective of the present work is to investigate the role of different grain sizes produced by equal channel angular pressing (ECAP) on the degradation behavior of magnesium alloy using in vitro and in vivo studies. Commercially available AZ31 magnesium alloy was selected and processed by ECAP at 300°C for up to four passes using route Bc. Grain refinement from a starting size of 46μm to a grain size distribution of 1-5μm was successfully achieved after the 4th pass. Wettability of ECAPed samples assessed by contact angle measurements was found to increase due to the fine grain structure. In vitro degradation and bioactivity of the samples studied by immersing in super saturated simulated body fluid (SBF 5×) showed rapid mineralization within 24h due to the increased wettability in fine grained AZ31 Mg alloy. Corrosion behavior of the samples assessed by weight loss and electrochemical tests conducted in SBF 5× clearly showed the prominent role of enhanced mineral deposition on ECAPed AZ31 Mg in controlling the abnormal degradation. Cytotoxicity studies by MTT colorimetric assay showed that all the samples are viable. Additionally, cell adhesion was excellent for ECAPed samples particularly for the 3rd and 4th pass samples. In vivo experiments conducted using New Zealand White rabbits clearly showed lower degradation rate for ECAPed sample compared with annealed AZ31 Mg alloy and all the samples showed biocompatibility and no health abnormalities were noticed in the animals after 60days of in vivo studies. These results suggest that the grain size plays an important role in degradation management of magnesium alloys and ECAP technique can be adopted to achieve fine grain structures for developing degradable magnesium alloys for biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Grain Cluster Microstructure and Grain Boundary Character Distribution in Alloy 690

NASA Astrophysics Data System (ADS)

Xia, Shuang; Zhou, Bangxin; Chen, Wenjue

2009-12-01

The effects of thermal-mechanical processing (TMP) on microstructure evolution during recrystallization and grain boundary character distribution (GBCD) in aged Alloy 690 were investigated by the electron backscatter diffraction (EBSD) technique and optical microscopy. The original grain boundaries of the deformed microstructure did not play an important role in the manipulation of the proportion of the Σ3 n ( n = 1, 2, 3…) type boundaries. Instead, the grain cluster formed by multiple twinning starting from a single nucleus during recrystallization was the key microstructural feature affecting the GBCD. All of the grains in this kind of cluster had Σ3 n mutual misorientations regardless of whether they were adjacent. A large grain cluster containing 91 grains was found in the sample after a small-strain (5 pct) and a high-temperature (1100 °C) recrystallization anneal, and twin relationships up to the ninth generation (Σ39) were found in this cluster. The ratio of cluster size over grain size (including all types of boundaries as defining individual grains) dictated the proportion of Σ3 n boundaries.

A Food Service Intervention Improves Whole Grain Access at Lunch in Rural Elementary Schools

PubMed Central

Cohen, Juliana F. W.; Rimm, Eric B.; Austin, S. Bryn; Hyatt, Raymond R.; Kraak, Vivica I.; Economos, Christina D.

2015-01-01

Background Whole grain (WG) options are often limited in schools, which may impact rural, low-income students who rely on school meals for a substantial portion of their food intake. This study examined the changes in the availability and quantity of WG and refined grain foods offered in schools participating in the Creating Healthy, Active and Nurturing Growing-up Environments (CHANGE) study, a randomized, controlled intervention among rural communities (4 intervention and 4 control). Methods Foods were assessed using production records, recipes, and nutrition labels from breakfast and lunch over 1week during fall 2008 and spring 2009. Key informant interviews were conducted with school food service directors in the spring 2009. Results The CHANGE intervention schools significantly increased the average percent of school days WGs were offered (p =.047) and the amount of WGs offered/food item (ounces) at lunch compared with control schools (p = .02). There was a significant decrease in the percent of students with access to refined grains at lunch compared with control schools (p =.049), although there were no significant differences in WG availability during breakfast. Conclusions The CHANGE schools improved WG availability, enabling student's WG consumption to be closer to national recommendations. PMID:24443783

A food service intervention improves whole grain access at lunch in rural elementary schools.

PubMed

Cohen, Juliana F W; Rimm, Eric B; Austin, S Bryn; Hyatt, Raymond R; Kraak, Vivica I; Economos, Christina D

2014-03-01

Whole grain (WG) options are often limited in schools, which may impact rural, low-income students who rely on school meals for a substantial portion of their food intake. This study examined the changes in the availability and quantity of WG and refined grain foods offered in schools participating in the Creating Healthy, Active and Nurturing Growing-up Environments (CHANGE) study, a randomized, controlled intervention among rural communities (4 intervention and 4 control). Foods were assessed using production records, recipes, and nutrition labels from breakfast and lunch over 1 week during fall 2008 and spring 2009. Key informant interviews were conducted with school food service directors in the spring 2009. The CHANGE intervention schools significantly increased the average percent of school days WGs were offered (p = .047) and the amount of WGs offered/food item (ounces) at lunch compared with control schools (p = .02). There was a significant decrease in the percent of students with access to refined grains at lunch compared with control schools (p = .049), although there were no significant differences in WG availability during breakfast. The CHANGE schools improved WG availability, enabling student's WG consumption to be closer to national recommendations. © 2014, American School Health Association.

Delamination Effect on Impact Properties of Ultrafine-Grained Low-Carbon Steel Processed by Warm Caliber Rolling

NASA Astrophysics Data System (ADS)

Inoue, Tadanobu; Yin, Fuxing; Kimura, Yuuji; Tsuzaki, Kaneaki; Ochiai, Shojiro

2010-02-01

Bulk ultrafine-grained (UFG) low-carbon steel bars were produced by caliber rolling, and the impact and tensile properties were investigated. Initial samples with two different microstructures, ferrite-pearlite and martensite (or bainite), were prepared and then caliber rolling was conducted at 500 °C. The microstructures in the rolled bars consisted of an elongated UFG structure with a strong α-fiber texture. The rolled bar consisting of spheroidal cementite particles that distributed uniformly in the elongated ferrite matrix of transverse grain sizes 0.8 to 1.0 μm exhibited the best strength-ductility balance and impact properties. Although the yield strength in the rolled bar increased 2.4 times by grain refinement, the upper-shelf energy did not change, and its value was maintained from 100 °C to -40 °C. In the rolled bars, cracks during an impact test branched parallel to the longitudinal direction of the test samples as temperatures decreased. Delamination caused by such crack branching appeared, remarkably, near the ductile-to-brittle transition temperature (DBTT). The effect of delamination on the impact properties was associated with crack propagation on the basis of the microstructural features in the rolled bars. In conclusion, the strength-toughness balance is improved by refining crystal grains and controlling their shape and orientation; in addition, delamination effectively enhances the low-temperature toughness.

The Coupling of Macrosegregation with Grain Nucleation, Growth and Motion in DC Cast Aluminum Alloy Ingots

NASA Astrophysics Data System (ADS)

Založnik, Miha; Kumar, Arvind; Combeau, Hervé; Bedel, Marie; Jarry, Philippe; Waz, Emmanuel

The phenomena responsible for the formation of macrosegregations, and grain structures during solidification are closely intertwined. We present a model study of the formation of macrosegregation and grain structure in an industrial sized (350 mm thick) direct chill (DC) cast aluminum alloy slab. The modeling of these phenomena in DC casting is a challenging problem mainly due to the size of the products, the variety of the phenomena to be accounted for, and the non-linearities involved. We used a volume-averaged multiscale model that describes nucleation on grain refiner particles and grain growth, coupled with macroscopic transport: fluid flow driven by natural convection and shrinkage, transport of free-floating globular equiaxed grains, heat transfer, and solute transport. We analyze the heat and mass transfer in the slurry moving-grain zone that is a result of the coupling of the fluid flow and of the grain nucleation, growth and motion. We discuss the impact of the flow structure in the slurry zone and of the grain packing fraction on the macrosegregation.

Containerless drop tube solidification and grain refinement of NiAl3

NASA Technical Reports Server (NTRS)

Ethridge, E. C.; Curreri, P. A.; Kelly, M.; Workman, G.; Smith, A. M.; Bond, R.

1984-01-01

The possibility of undercooling Ni-Al alloys below the liquidus in order to produce a single phase peritectic structure by containerless drop tube solidification was studied. Containerless process is a technique for both high purity contamination free studies as well as for investigating the undercooling and rapid solidification of alloys by suppression of heterogeneous nucleation on container walls. In order to achieve large undercoolings one must avoid heterogeneous nucleation of crystallization. It was shown that the Marshall Space Flight Center drop tubes ae unique facilities for containerless solidification experiments and large undercoolings are possible with some alloys. The original goal of undercooling the liquid metal well below the liquidus to the peritectic temperature during containerless free to form primarily NiAl3 was achieved. The microstructures were interesting from another point of view. The microstructure from small diameter samples is greatly refined. Small dendrite arm spacings such as these could greatly facilitate the annealing and solid state transformation of the alloy to nearly 10% NiAl3 by reducing the distance over which diffusion needs to occur. This could minimize annealing time and might make it economically feasible to produce NiAl3 alloy.

Whole Grains Contribute Only a Small Proportion of Dietary Fiber to the U.S. Diet

PubMed Central

Kranz, Sibylle; Dodd, Kevin W.; Juan, Wen Yen; Johnson, LuAnn K.; Jahns, Lisa

2017-01-01

Dietary fiber (DF), found in whole fruits, vegetables, and whole grains (WG), is considered a nutrient of concern in the US diet and increased consumption is recommended. The present study was designed to highlight this critical importance of the difference between WG, high-fiber WG, and sources of fiber that are not from WG. The study is based on the two-day diets reported consumed by the nationally representative sample of Americans participating in What We Eat In America, the dietary component of the National Health and Nutrition Examination Survey from 2003–2010. Foods consumed were classified into tertiles of DF and WG and the contribution of fiber by differing levels of WG content were examined. Foods containing high amounts of WG and DF only contributed about 7% of total fiber intake. Overall, grain-based foods contributed 54.5% of all DF consumed. Approximately 39% of DF came from grain foods that contained no WG, rather these foods contained refined grains, which contain only small amounts of DF but are consumed in large quantities. All WG-containing foods combined contributed a total of 15.3% of DF in the American diet. Thus, public health messaging needs to be changed to specifically encourage consumption of WG foods with high levels of DF to address both recommendations. PMID:28218657

Simultaneous Feulgen densitometry and autoradiographic grain counting with the Quantimet 720D image-analysis system. III. Improvements in Feulgen densitometry.

PubMed

Sklarew, R J

1983-10-01

A method has been developed for densitometric estimation of the Feulgen-stained DNA content of 3H-labeled nuclei in autoradiographs in conjunction with automated grain counting using a Quantimet Imaging System. Refinements in the methodology are reported which include 1) the incorporation of an Image-Editor Module into the Quantimet module configuration; 2) the optimization of incident illumination based upon evaluation of various light sources; 3) changes in the optical configuration which reduce glare and minimize the level of monitor shading correction; 4) the optimization of scanner sensitivity; and 5) the evaluation of cell-flattening and staining with respect to densitometry resolution and sensitivity. These refinements resulted in a CV of less than 6.4% in the G-1 and G-2 DNA peaks of rat kidney cells in autoradiographs compared to the previous CV of 10.5%, and a G-2 to G-1 ratio of 2.025. For a fixed field position the CV was 5.1% and the replication error less than 1.0%.

Grain refinement in heavy rare earth element-free sintered Nd–Fe–B magnets by addition of a small amount of molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jin Woo; Lee, Won Suk; Byun, Jong Min

2015-05-07

We employed a modified refractory-metal-addition method to achieve higher coercivity and remanence in heavy rare earth element (HREE)-free Nd–Fe–B sintered magnets. This process involved inducing the formation of a homogeneous secondary phase at the grain boundaries during sintering, making it possible to control the intergrain diffusion by adding small amounts of Mo, a refractory metal. To control the microstructure of the secondary phase effectively, a metal organic compound of the refractory metal was coated on the surfaces of the particles of an HREE-free Nd–Fe–B powder. The average grain size after this process was 5.60 μm, which was approximately 1.8 μm smaller thanmore » that of the HREE-free sintered Nd–Fe–B magnets (7.4 μm). The coercivity of the magnets prepared through this process could be increased from 11.88 kOe to 13.91 kOe without decreasing their remanence.« less

Energy storage properties of Dy3+ doped Sr0.5Ba0.5Nb2O6 thick film with nano-size grains

NASA Astrophysics Data System (ADS)

Yang, Daeyeol; Kang, Soo-Bin; Lim, Ji-Ho; Yoon, Songhyeon; Ryu, Jungho; Choi, Jong-Jin; Velayutham, Thamil Selvi; Kim, Hyungsun; Jeong, Dae-Yong

2017-09-01

We studied the temperature stable high-energy storage capacitors. Sr0.5Ba0.5Nb2O6 (SBN) is the lead-free ferroelectric solid solution between BaNb2O6 and SrNb2O6. By doping Dy into SBN, the Curie temperature was lowered and dielectric constant was increased. To improve the breakdown behavior of Dy-doped SBN, the aerosoldeposition(AD) was applied to fabricate the dense films with nano-sized grains. These nano-grain give a large number of grain boundaries, suppressing the electron conduction in ceramics. The dielectric constant and breakdown electric field of the AD films annealed at 650 °C were measured as 2307 and 9.9 MV/m, while bulk were 1080 and 4 MV/m. Energy density and efficiency of the AD films annealed at 650 °C were also enhanced as 0.65 J/cc and 90.2% and bulk were 0.08 J/cc and 72.1%, respectively. In addition, the dielectric constant of AD film annealed at 550 °C and 650 °C were quite stable up to 150 °C.

Effects of Temperature and Pressure of Hot Isostatic Pressing on the Grain Structure of Powder Metallurgy Superalloy

PubMed Central

Tan, Liming; He, Guoai; Liu, Feng; Li, Yunping; Jiang, Liang

2018-01-01

The microstructure with homogeneously distributed grains and less prior particle boundary (PPB) precipitates is always desired for powder metallurgy superalloys after hot isostatic pressing (HIPping). In this work, we studied the effects of HIPping parameters, temperature and pressure on the grain structure in PM superalloy FGH96, by means of scanning electron microscope (SEM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and Time-of-flight secondary ion spectrometry (ToF-SIMS). It was found that temperature and pressure played different roles in controlling PPB precipitation and grain structure during HIPping, the tendency of grain coarsening under high temperature could be inhibited by increasing HIPping pressure which facilitates the recrystallization. In general, relatively high temperature and pressure of HIPping were preferred to obtain an as-HIPped superalloy FGH96 with diminished PPB precipitation and homogeneously refined grains. PMID:29495312

Effects of Temperature and Pressure of Hot Isostatic Pressing on the Grain Structure of Powder Metallurgy Superalloy.

PubMed

Tan, Liming; He, Guoai; Liu, Feng; Li, Yunping; Jiang, Liang

2018-02-24

The microstructure with homogeneously distributed grains and less prior particle boundary (PPB) precipitates is always desired for powder metallurgy superalloys after hot isostatic pressing (HIPping). In this work, we studied the effects of HIPping parameters, temperature and pressure on the grain structure in PM superalloy FGH96, by means of scanning electron microscope (SEM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and Time-of-flight secondary ion spectrometry (ToF-SIMS). It was found that temperature and pressure played different roles in controlling PPB precipitation and grain structure during HIPping, the tendency of grain coarsening under high temperature could be inhibited by increasing HIPping pressure which facilitates the recrystallization. In general, relatively high temperature and pressure of HIPping were preferred to obtain an as-HIPped superalloy FGH96 with diminished PPB precipitation and homogeneously refined grains.

Effect of Sn Grain Orientation on the Cu6Sn5 Formation in a Sn-Based Solder Under Current Stressing

NASA Astrophysics Data System (ADS)

Lin, Chih-Fan; Lee, Shang-Hua; Chen, Chih-Ming

2012-08-01

A SnAgCu-based solder stripe between two Cu electrodes is current stressed with a density of 5 × 104 A/cm2 at 393 K (120 °C). After current stressing for 24 hours, electromigration induces the Cu dissolution from the cathode-side Cu electrode, leading to the Cu6Sn5 formation in the solder stripe. Very interestingly, the Cu6Sn5 phase is selectively formed within a specific Sn grain. Electron backscattering diffraction analysis indicates the crystallographic orientations of Sn grains play an important role in the selective Cu6Sn5 formation.

3.5-D model of sediment age and grain size for the Northern Gulf of Aqaba-Elat (Red Sea) using submarine cores

NASA Astrophysics Data System (ADS)

Kanari, Mor; Ben-Avraham, Zvi; Tibor, Gideon; Goodman Tchernov, Beverly N.; Bookman, Revital; Taha, Nimer; Marco, Shmuel

2016-04-01

The Northern Gulf of Aqaba-Elat (NGAE) is the northeast extension of the Red Sea, located at the southernmost part of the Dead Sea Fault, at the transition zone between the deep en-echelon submarine basins of the Red Sea and the shallow continental basins of the Arava Valley (Israel and Jordan). We aim to characterize the top sedimentary cover across the NGAE in order to check the effect of tectonics on the sedimentary column, using high resolution grain size data and radiocarbon dating of core sediments. We analyzed 11 piston cores and 9 short cores: high resolution grain-size and radiocarbon age determinations were used to compile a 3.5-D (3.5 dimensional) model of age-depth-grain size for the top 3-5 meters of the NGAE. Two general trends of the grain size spatial distribution are observed: grains are coarsest at the NE corner of the NGAE (Aqaba coastline) and grow finer with the distance to the west on the shelf and with the distance from shore to the south. Long- and short-term accumulation rates were compiled for the entire NGAE, demonstrating a distinct E-W trend on the shelf and a NNE-SSW trend in the deep basin. The 3.5-D age-depth-grain size model conforms to- and validates the tectonic structure of the shelf detailed by previous authors. We suggest that the impact of tectonic structure of the shelf is highly significant in terms of spatial variations across the shelf, both in age of the sediment and its grain size characteristics. The temporal-spatial distribution of the grain size in the deep basin of the NGAE reveals a correlation between sediment age, dominant grain size and active tectonics: fine-grain, old sediment in the margins (Late Pleistocene, as old as >40 ka on the west margin; Early Holocene, as old as 7.5 ka, on the east margin), and Late Pleistocene sediment farther south from the dominant active diagonal fault which underlies the Elat Canyon. Young coarse sediment is present in the middle of the basin, where most of the active sediment

The effects of moderate whole grain consumption on fasting glucose and lipids, gastrointestinal symptoms, and microbiota

USDA-ARS?s Scientific Manuscript database

This study was designed to determine if providing wheat, corn, and rice as whole (WG) or refined grains (RG) under free-living conditions will change parameters of health over a six-week intervention in healthy, habitual non-WG consumers. Measurements of body composition, fecal microbiota, fasting ...

Microstructure, microtexture and precipitation in the ultrafine-grained surface layer of an Al-Zn-Mg-Cu alloy processed by sliding friction treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yanxia

2017-01-15

Precipitate redistribution and texture evolution are usually two concurrent aspects accompanying grain refinement induced by various surface treatment. However, the detailed precipitate redistribution characteristics and process, as well as crystallographic texture in the surface refined grain layer, are still far from full understanding. In this study, we focused on the microstructural and crystallographic features of the sliding friction treatment (SFT) induced surface deformation layer in a 7050 aluminum alloy. With the combination of transmission electron microscopy (TEM) and high angle angular dark field scanning TEM (HAADF-STEM) observations, a surface ultrafine grain (UFG) layer composed of both equiaxed and lamellar ultrafinemore » grains and decorated by high density of coarse grain boundary precipitates (GBPs) were revealed. Further precession electron diffraction (PED) assisted orientation mapping unraveled that high angle grain boundaries rather than low angle grain boundaries are the most favorable nucleation sites for GBPs. The prominent precipitate redistribution can be divided into three successive and interrelated stages, i.e. the mechanically induced precipitate dissolution, solute diffusion and reprecipitation. The quantitative prediction based on pipe diffusion along dislocations and grain boundary diffusion proved the distribution feasibility of GBPs around UFGs. Based on PED and electron backscatter diffraction (EBSD) analyses, the crystallographic texture of the surface UFG layer was identified as a shear texture composed of major rotated cube texture (001) 〈110〉 and minor (111) 〈112〉, while that of the adjoining lamellar coarse grained matrix was pure brass. The SFT induced surface severe shear deformation is responsible for texture evolution. - Highlights: •The surface ultrafine grain layer in a 7050 aluminum alloy was focused. •Precipitate redistribution and texture evolution were discussed. •The quantitative prediction

New Robust Reference Materials for In Situ Single Grain Rutile U-Pb Geochronology and Method Refinements for Detrital Rutile Analysis by LA-MC-ICP-MS

NASA Astrophysics Data System (ADS)

Parrish, R. R.; Bracciali, L.; Condon, D. J.; Horstwood, M. S.; Najman, Y.

2012-12-01

While rutile (TiO2) occurs in the heavy mineral suite of detrital sediments and originates mainly in medium- to high-grade metamorphic and some igneous rocks, there are very few applications of U-Pb dating of rutile to provenance studies; this is due to an overreliance on zircon, low U content of rutile limiting measurement quality by in situ methods, a higher proportion of common Pb relative to zircon, and a lack of widely available good quality reference materials. We have addressed these issues and characterized two ~ 1.8 Ga rutile reference materials by SEM, trace elements, U-Pb ID-TIMS, and intra-grain and inter-grain U-Pb LA-MC-ICP-MS analysis using mixed faraday and multiple ion counting detectors with high sensitivity. We have assessed U-Pb discordance and in situ variations in relative common Pb and age and their bearing on the quality of the reference materials for in situ U-Pb dating. The rutiles (Sugluk-4 and PCA-S207) come from granulite facies belts of the Canadian Shield, namely the northern Cape Smith Belt of Quebec and the Snowbird Tectonic Zone (Sasatchewan). The ID-TIMS data are slightly discordant due to variable common Pb and limited Pb loss; the variation in 6 single grains of Sugluk-4, that we use as the primary reference material, is <1% in 206Pb/238U, and <2% for 207Pb/206Pb (95 % conf.); after common Pb correction these variations are <1%. The measured variations are smaller than in existing reference materials (i.e. R10) in current use. LA-ICP-MC-MS data (n ~ 500 for each) have a reproducibility of 206Pb/238U and 207Pb/206Pb of ~2-4% (at the 2S level), which is only modestly worse than long-term data for multiple zircon standards, this being due to the real variation in measured values arising from limited Pb loss, age variation, and common Pb variability [1]. We have applied our refined method to the provenance of rutile from drainages from British Columbia, Bhutan, and the Brahmaputra River of NE India (predominant rutile ages ~ 50, 15

The role of ultrasonic cavitation in refining the microstructure of aluminum based nanocomposites during the solidification process.

PubMed

Xuan, Yang; Nastac, Laurentiu

2018-02-01

Recent studies showed that the microstructure and mechanical properties of aluminum based nanocomposites can be significantly improved when ultrasonic cavitation and solidification processing is used. This is because ultrasonic cavitation processing plays an important role not only in degassing and dispersion of the nanoparticles, but also in breaking up the dendritic grains and refining the as-cast microstructure. In the present study, A356 alloy and Al 2 O 3 nanoparticles are used as the matrix alloy and the reinforcement, respectively. Nanoparticles were added into the molten A356 alloy and dispersed via ultrasonic cavitation processing. Ultrasonic cavitation was applied over various temperature ranges during molten alloy cooling and solidification to investigate the grain structure formation and the nanoparticle dispersion behavior. Optical Microscopy and Scanning Electron Microscopy were used to investigate in detail the differences in the microstructure characteristics and the nanoparticle distribution. Experimental results indicated that the ultrasonic cavitation processing and Al 2 O 3 nanoparticles play an important role for microstructure refinement. In addition, it was shown in this study that the Al 2 O 3 nanoparticles modified the eutectic phase. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of high pressure torsion on structural refinement and mechanical properties of an austenitic stainless steel.

PubMed

Krawczynska, Agnieszka Teresa; Lewandowska, Malgorzata; Pippan, Reinhard; Kurzydlowski, Krzysztof Jan

2013-05-01

In the present study, the high pressure torsion (HPT) was used to refine the grain structure down to the nanometer scale in an austenitic stainless steel. The principles of HPT lay on torsional deformation under simultaneous high pressure of the specimen, which results in substantial reduction in the grain size. Disks of the 316LVM austenitic stainless steel of 10 mm in diameter were subjected to equivalent strains epsilon of 32 at RT and 450 degrees C under the pressure of 4 GPa. Furthermore, two-stage HPT processes, i.e., deformation at room temperature followed by deformation at 450 degrees C, were performed. The resulting microstructures were investigated in TEM observations. The mechanical properties were measured in terms of the microhardness and in tensile tests. HPT performed at two-stage conditions (firstly at RT next at 450 degrees C) gives similar values of microhardness to the ones obtained after deforming only at 450 degrees C but performed to higher values of the overall equivalent strain epsilon. The effect of high pressure torsion on structural refinement and mechanical properties of an austenitic stainless steel was evaluated.

Strain Amount Dependent Grain Size and Orientation Developments during Hot Compression of a Polycrystalline Nickel Based Superalloy

PubMed Central

He, Guoai; Tan, Liming; Liu, Feng; Huang, Lan; Huang, Zaiwang; Jiang, Liang

2017-01-01

Controlling grain size in polycrystalline nickel base superalloy is vital for obtaining required mechanical properties. Typically, a uniform and fine grain size is required throughout forging process to realize the superplastic deformation. Strain amount occupied a dominant position in manipulating the dynamic recrystallization (DRX) process and regulating the grain size of the alloy during hot forging. In this article, the high-throughput double cone specimen was introduced to yield wide-range strain in a single sample. Continuous variations of effective strain ranging from 0.23 to 1.65 across the whole sample were achieved after reaching a height reduction of 70%. Grain size is measured to be decreased from the edge to the center of specimen with increase of effective strain. Small misorientation tended to generate near the grain boundaries, which was manifested as piled-up dislocation in micromechanics. After the dislocation density reached a critical value, DRX progress would be initiated at higher deformation region, leading to the refinement of grain size. During this process, the transformations from low angle grain boundaries (LAGBs) to high angle grain boundaries (HAGBs) and from subgrains to DRX grains are found to occur. After the accomplishment of DRX progress, the neonatal grains are presented as having similar orientation inside the grain boundary. PMID:28772514

Simultaneous use of solution NMR and X-ray data in REFMAC5 for joint refinement/detection of structural differences.

PubMed

Rinaldelli, Mauro; Ravera, Enrico; Calderone, Vito; Parigi, Giacomo; Murshudov, Garib N; Luchinat, Claudio

2014-04-01

The program REFMAC5 from CCP4 was modified to allow the simultaneous use of X-ray crystallographic data and paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and/or diamagnetic residual dipolar couplings. Incorporation of these long-range NMR restraints in REFMAC5 can reveal differences between solid-state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. Since NMR and X-ray data are complementary, when a single structure is consistent with both sets of data and still maintains reasonably `ideal' geometries, the reliability of the derived atomic model is expected to increase. The program was tested on five different proteins: the catalytic domain of matrix metalloproteinase 1, GB3, ubiquitin, free calmodulin and calmodulin complexed with a peptide. In some cases the joint refinement produced a single model consistent with both sets of observations, while in other cases it indicated, outside the experimental uncertainty, the presence of different protein conformations in solution and in the solid state.

Replacing with whole grains and legumes reduces Lp-PLA2 activities in plasma and PBMCs in patients with prediabetes or T2D1

PubMed Central

Kim, Minjoo; Jeung, Se Ri; Jeong, Tae-Sook; Lee, Sang-Hyun; Lee, Jong Ho

2014-01-01

To determine dietary effects on circulating lipoprotein-associated phospholipase A2 (Lp-PLA2) activity and enzyme activity in peripheral blood mononuclear cells (PBMCs), 99 patients with impaired fasting glucose, impaired glucose tolerance, or newly-diagnosed T2D were randomly assigned to either a control group (usual diet with refined rice) or the whole grain and legume group. Substitution of whole grains and legumes for refined rice was associated with the replacement of 7% of energy from carbohydrates with energy from protein (about 4%) and fat. After 12 weeks, the whole grain and legume group showed a significant decrease in fasting glucose, insulin, homeostasis model assessment-insulin resistance, hemoglobin A1c, malondialdehyde, plasma Lp-PLA2 activity, and oxidized LDL (ox-LDL), and an increase in LDL particle size. The changes (Δs) in these variables in the whole grain and legume group were significantly different from those in controls after adjustment for the baseline levels. When all subjects were considered, Δ plasma Lp-PLA2 positively correlated with Δ glucose, Δ PBMC Lp-PLA2, Δ ox-LDL, and Δ urinary 8-epi-prostaglandin F2α after being adjusted for confounding factors. The Δ PBMC Lp-PLA2 correlated positively with Δ glucose and Δ ox-LDL, and negatively with Δ LDL particle size and baseline PBMC Lp-PLA2. The substitution of whole grains and legumes for refined rice resulted in a reduction in Lp-PLA2 activities in plasma and PBMCs partly through improved glycemic control, increased consumption of protein relative to carbohydrate, and reduced lipid peroxides. PMID:24904022

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-07-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-04-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Refined generalized multiscale entropy analysis for physiological signals

NASA Astrophysics Data System (ADS)

Liu, Yunxiao; Lin, Youfang; Wang, Jing; Shang, Pengjian

2018-01-01

Multiscale entropy analysis has become a prevalent complexity measurement and been successfully applied in various fields. However, it only takes into account the information of mean values (first moment) in coarse-graining procedure. Then generalized multiscale entropy (MSEn) considering higher moments to coarse-grain a time series was proposed and MSEσ2 has been implemented. However, the MSEσ2 sometimes may yield an imprecise estimation of entropy or undefined entropy, and reduce statistical reliability of sample entropy estimation as scale factor increases. For this purpose, we developed the refined model, RMSEσ2, to improve MSEσ2. Simulations on both white noise and 1 / f noise show that RMSEσ2 provides higher entropy reliability and reduces the occurrence of undefined entropy, especially suitable for short time series. Besides, we discuss the effect on RMSEσ2 analysis from outliers, data loss and other concepts in signal processing. We apply the proposed model to evaluate the complexity of heartbeat interval time series derived from healthy young and elderly subjects, patients with congestive heart failure and patients with atrial fibrillation respectively, compared to several popular complexity metrics. The results demonstrate that RMSEσ2 measured complexity (a) decreases with aging and diseases, and (b) gives significant discrimination between different physiological/pathological states, which may facilitate clinical application.

On the Use of Dynamical Diffraction Theory To Refine Crystal Structure from Electron Diffraction Data: Application to KLa5O5(VO4)2, a Material with Promising Luminescent Properties.

PubMed

Colmont, Marie; Palatinus, Lukas; Huvé, Marielle; Kabbour, Houria; Saitzek, Sébastien; Djelal, Nora; Roussel, Pascal

2016-03-07

A new lanthanum oxide, KLa5O5(VO4)2, was synthesized using a flux growth technique that involved solid-state reaction under an air atmosphere at 900 °C. The crystal structure was solved and refined using an innovative approach recently established and based on three-dimensional (3D) electron diffraction data, using precession of the electron beam and then validated against Rietveld refinement and denisty functional theory (DFT) calculations. It crystallizes in a monoclinic unit cell with space group C2/m and has unit cell parameters of a = 20.2282(14) Å, b = 5.8639(4) Å, c = 12.6060(9) Å, and β = 117.64(1)°. Its structure is built on Cresnel-like two-dimensional (2D) units (La5O5) of 4*3 (OLa4) tetrahedra, which run parallel to (001) plane, being surrounded by isolated VO4 tetrahedra. Four isolated vanadate groups create channels that host K(+) ions. Substitution of K(+) cations by another alkali metal is possible, going from lithium to rubidium. Li substitution led to a similar phase with a primitive monoclinic unit cell. A complementary selected area electron diffraction (SAED) study highlighted diffuse streaks associated with stacking faults observed on high-resolution electron microscopy (HREM) images of the lithium compound. Finally, preliminary catalytic tests for ethanol oxidation are reported, as well as luminescence evidence. This paper also describes how solid-state chemists can take advantages of recent progresses in electron crystallography, assisted by DFT calculations and powder X-ray diffraction (PXRD) refinements, to propose new structural types with potential applications to the physicist community.

DELIVERY OF DUST GRAINS FROM COMET C/2013 A1 (SIDING SPRING) TO MARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tricarico, Pasquale; Samarasinha, Nalin H.; Sykes, Mark V.

Comet C/2013 A1 (Siding Spring) will have a close encounter with Mars on 2014 October 19. We model the dynamical evolution of dust grains from the time of their ejection from the comet nucleus to the close encounter with Mars, and determine the flux at Mars. Constraints on the ejection velocity from Hubble Space Telescope observations indicate that the bulk of the grains will likely miss Mars, although it is possible that a few percent of the grains with higher velocities will reach Mars, peaking approximately 90-100 minutes after the close approach of the nucleus, and consisting mostly of millimeter-radiusmore » grains ejected from the comet nucleus at a heliocentric distance of approximately 9 AU or larger. At higher velocities, younger grains from submillimeter to several millimeters can also reach Mars, although an even smaller fraction of grains is expected have these velocities, with negligible effect on the peak timing. Using NEOWISE observations of the comet, we can estimate that the maximum fluence will be of the order of 10{sup –7} grains m{sup –2}. We include a detailed analysis of how the expected fluence depends on the grain density, ejection velocity, and size-frequency distribution, to account for current model uncertainties and in preparation of possible refined model values in the near future.« less

Grain fragmentation in ultrasonic-assisted TIG weld of pure aluminum.

PubMed

Chen, Qihao; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Ge, Hongliang

2017-11-01

Under the action of acoustic waves during an ultrasonic-assisted tungsten inert gas (TIG) welding process, a grain of a TIG weld of aluminum alloy is refined by nucleation and grain fragmentation. Herein, effects of ultrasound on grain fragmentation in the TIG weld of aluminum alloy are investigated via systematic welding experiments of pure aluminum. First, experiments involving continuous and fixed-position welding are performed, which demonstrate that ultrasound can break the grain of the TIG weld of pure aluminum. The microstructural characteristics of an ultrasonic-assisted TIG weld fabricated by fixed-position welding are analyzed. The microstructure is found to transform from plane crystal, columnar crystal, and uniform equiaxed crystal into plane crystal, deformed columnar crystal, and nonuniform equiaxed crystal after application of ultrasound. Second, factors influencing ultrasonic grain fragmentation are investigated. The ultrasonic amplitude and welding current are found to have a considerable effect on grain fragmentation. The degree of fragmentation first increases and then decreases with an increase in ultrasonic amplitude, and it increases with an increase in welding current. Measurement results of the vibration of the weld pool show that the degree of grain fragmentation is related to the intensity of acoustic nonlinearity in the weld pool. The greater the intensity of acoustic nonlinearity, the greater is the degree of grain fragmentation. Finally, the mechanism of ultrasonic grain fragmentation in the TIG weld of pure aluminum is discussed. A finite element simulation is used to simulate the acoustic pressure and flow in the weld pool. The acoustic pressure in the weld pool exceeds the cavitation threshold, and cavitation bubbles are generated. The flow velocity in the weld pool does not change noticeably after application of ultrasound. It is concluded that the high-pressure conditions induced during the occurrence of cavitation, lead to grain

40 CFR 80.1340 - How does a refiner obtain approval as a small refiner?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Provisions § 80.1340 How does a refiner obtain approval as a small refiner? (a) Applications for small refiner status must be submitted to EPA by December 31, 2007. (b) For U.S. Postal delivery, applications... small refiner status application must contain the following information for the company seeking small...

White Whole-Wheat Flour Can Be Partially Substituted for Refined-Wheat Flour in Pizza Crust in School Meals without Affecting Consumption

ERIC Educational Resources Information Center

Chan, Hing Wan; Burgess Champoux, Teri; Reicks, Marla; Vickers, Zata; Marquart, Len

2008-01-01

Objectives: Recent dietary guidance recommends that children consume at least three servings of whole-grains daily. This study examined whether white whole-wheat (WWW) flour can be partially substituted for refined-wheat (RW) flour in pizza crust without affecting consumption by children in a school cafeteria. Methods: Subjects included first to…

Suppression of Twinning and Phase Transformation in an Ultrafine Grained 2 GPa Strong Metastable Austenitic Steel: Experiment and Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yongfeng; Jia, Nan; Wang, Y. D.

2015-07-17

An ultrafine-grained 304 austenitic 18 wt.%Cr-8 wt.%Ni stainless steel with a grain size of ~270 nm was synthesized by accumulative rolling (67 % total reduction) and annealing (550 °C, 150s). Uniaxial tensile testing at room temperature reveals an extremely high yield strength of 1890 ± 50MPa and a tensile strength of 2050 ± 30MPa, while the elongation reaches 6 ± 1%. Experimental characterization on samples with different grain sizes between 270 nm and 35 μm indicates that both, deformation twinning and martensitic phase transformation are significantly retarded with increasing grain refinement. A crystal plasticity finite element model incorporating a constitutivemore » law reflecting the grain size-controlled dislocation slip and deformation twinning captures the micromechanical behavior of the steels with different grain sizes. Comparison of simulation and experiment shows that the deformation of ultrafine-grained 304 steels is dominated by the slip of partial dislocations, whereas for coarse-grained steels dislocation slip, twinning and martensite formation jointly contribute to the shape change.« less

Apparent consumption of refined sugar in Australia (1938-2011).

PubMed

McNeill, T J; Shrapnel, W S

2015-11-01

In Australia, the Australian Bureau of Statistics discontinued collection of apparent consumption data for refined sugars in 1998/1999. The objectives of this study were to update this data series to determine whether it is a reliable data series that reflects consumption of refined sugars, defined as sucrose in the forms of refined or raw sugar or liquified sugars manufactured for human consumption. The study used the same methodology as that used by the Australian Bureau of Statistics to derive a refined sugars consumption estimate each year until the collection was discontinued. Sales by Australian refiners, refined sugars imports and the net balance of refined sugars contained in foods imported into, and exported from, Australia were used to calculate total refined sugars use for each year up to 2011. Per capita consumption figures were then derived. During the period 1938-2011, apparent consumption of refined sugars in Australia fell 13.1% from 48.3 to 42.0 kg per head (R(2)=0.74). Between the 1950s and the 1970s, apparent consumption was relatively stable at about 50 kg per person. In the shorter period 1970-2011, refined sugars consumption fell 16.5% from 50.3 to 42.0 kg per head, though greater variability was evident (R(2)=0.53). An alternative data set showed greater volatility with no trend up or down. The limited variability of the extended apparent consumption series and its consistency with recent national dietary survey data and sugar-sweetened beverage sales data indicate that it is a reliable data set that reflects declining intake of refined sugars in Australia.

Disintegration of the net-shaped grain-boundary phase by multi-directional forging and its influence on the microstructure and properties of Cu-Ni-Si alloy

NASA Astrophysics Data System (ADS)

Zhang, Jinlong; Lu, Zhenlin; Zhao, Yuntao; Jia, Lei; Xie, Hui; Tao, Shiping

2017-09-01

Cu-Ni-Si alloys with 90% Cu content and Ni to Si ratios of 5:1 were fabricated by fusion casting, and severe plastic deformation of the Cu-Ni-Si alloy was carried out by multi-direction forging (MDF). The results showed that the as-cast and homogenized Cu-Ni-Si alloys consisted of three phases, namely the matrix phase α-Cu (Ni, Si), the reticular grain boundary phase Ni31Si12 and the precipitated phase Ni2Si. MDF significantly destroyed the net-shaped grain boundary phase, the Ni31Si12 phase and refined the grain size of the Cu matrix, and also resulted in the dissolving of Ni2Si precipitates into the Cu matrix. The effect of MDF on the conductivity of the solid solution Cu-Ni-Si alloy was very significant, with an average increase of 165.16%, and the hardness of the Cu-Ni-Si alloy also increased obviously.

Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

NASA Astrophysics Data System (ADS)

Xia, Minglu; Sun, Qingping

2017-10-01

Grain size effects on stability of thermomechanical responses for a nonlinear torsional vibration system with nanocrystalline superelastic NiTi bar are investigated in the frequency and amplitude domains. NiTi bars with average grain size from 10 nm to 100 nm are fabricated through cold-rolling and subsequent annealing. Thermomechanical responses of the NiTi bar as a softening nonlinear damping spring in the torsional vibration system are obtained by synchronised acquisition of rotational angle and temperature under external sinusoidal excitation. It is shown that nonlinearity and damping capacity of the NiTi bar decrease as average grain size of the material is reduced below 100 nm. Therefore jump phenomena of thermomechanical responses become less significant or even vanish and the vibration system becomes more stable. The work in this paper provides a solid experimental base for manipulating the undesired jump phenomena of thermomechanical responses and stabilising the mechanical vibration system through grain refinement of NiTi SMA.

Transitional grain-size-sensitive flow of milky quartz aggregates

NASA Astrophysics Data System (ADS)

Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

2014-12-01

Fine-grained (~15 μm) milky quartz aggregates exhibit reversible flow strengths in triaxial compression experiments conducted at T = 800-900oC, Pc = 1.5 GPa when strain rates are sequentially decreased (typically from 10-3.5 to 10-4.5 and 10-5.5 s-1), and then returned to the original rate (10-3.5 s-1), while samples that experience grain growth at 1000oC (to 35 μm) over the same sequence of strain rates exhibit an irreversible increase in strength. Polycrystalline quartz aggregates have been synthesized from natural milky quartz powders (ground to 5 μm) by HIP methods at T = 1000oC, Pc = 1.5 GPa and t = 24 hours, resulting in dense, fine-grained aggregates of uniform water content of ~4000 ppm (H/106Si), as indicated by a broad OH absorption band at 3400 cm-1. In experiments performed at 800o and 900oC, grain sizes of the samples are essentially constant over the duration of each experiment, though grain shapes change significantly, and undulatory extinction and deformation lamellae indicate that much of the sample shortening (to 50%) is accomplished, over the four strain-rate steps, by dislocation creep. Differential stresses measured at T = 800oC decrease from 160 to 30 MPa as strain rate is reduced from 10-4.6 to 10-5.5 s-1, and a stress of 140 MPa is measured when strain rate is returned to 10-4.5 s-1. Samples deformed at 1000o and 1100oC experience normal grain growth, with grain boundary energy-driven grain-coarsening textures superposed by undulatory extinction and deformation lamellae. Differential stresses measured at 1000oC and strain rates of 10-3.6, 10-4.6, and 10-5.5 s-1 are 185, 80, and 80 MPa, respectively, while an increased flow stress of 260 MPa is measured (following ~28 hours of prior high temperature deformation and grain growth) when strain rate is returned to 10-3.6 s-1. While all samples exhibit lattice preferred orientations, the stress exponent n inferred for the fine-grained 800oC sample is 1.5 and the stress exponent of the coarse-grained

Multidataset Refinement Resonant Diffraction, and Magnetic Structures

PubMed Central

Attfield, J. Paul

2004-01-01

The scope of Rietveld and other powder diffraction refinements continues to expand, driven by improvements in instrumentation, methodology and software. This will be illustrated by examples from our research in recent years. Multidataset refinement is now commonplace; the datasets may be from different detectors, e.g., in a time-of-flight experiment, or from separate experiments, such as at several x-ray energies giving resonant information. The complementary use of x rays and neutrons is exemplified by a recent combined refinement of the monoclinic superstructure of magnetite, Fe3O4, below the 122 K Verwey transition, which reveals evidence for Fe2+/Fe3+ charge ordering. Powder neutron diffraction data continue to be used for the solution and Rietveld refinement of magnetic structures. Time-of-flight instruments on cold neutron sources can produce data that have a high intensity and good resolution at high d-spacings. Such profiles have been used to study incommensurate magnetic structures such as FeAsO4 and β–CrPO4. A multiphase, multidataset refinement of the phase-separated perovskite (Pr0.35Y0.07Th0.04Ca0.04Sr0.5)MnO3 has been used to fit three components with different crystal and magnetic structures at low temperatures. PMID:27366599

Strontium and barium isotopes in presolar silicon carbide grains measured with CHILI-two types of X grains

NASA Astrophysics Data System (ADS)

Stephan, Thomas; Trappitsch, Reto; Davis, Andrew M.; Pellin, Michael J.; Rost, Detlef; Savina, Michael R.; Jadhav, Manavi; Kelly, Christopher H.; Gyngard, Frank; Hoppe, Peter; Dauphas, Nicolas

2018-01-01

We used CHILI, the Chicago Instrument for Laser Ionization, a new resonance ionization mass spectrometer developed for isotopic analysis of small samples, to analyze strontium, zirconium, and barium isotopes in 22 presolar silicon carbide grains. Twenty of the grains showed detectable strontium and barium, but none of the grains had enough zirconium to be detected with CHILI. Nine grains were excluded from further consideration since they showed very little signals (<1000 counts) for strontium as well as for barium. Among the 11 remaining grains, we found three X grains. The discovery of three supernova grains among only 22 grains was fortuitous, because only ∼1% of presolar silicon carbide grains are type X, but was confirmed by silicon isotopic measurements of grain residues with NanoSIMS. While one of the X grains showed strontium and barium isotope patterns expected for supernova grains, the two other supernova grains have 87Sr/86Sr < 0.5, values never observed in any natural sample before. From their silicon isotope ratios, the latter two grains can be classified as X2 grains, while the former grain belongs to the more common X1 group. The differences of these grains in strontium and barium isotopic composition constrain their individual formation conditions in Type II supernovae.

Grain-grain interaction in stationary dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lampe, Martin; Joyce, Glenn

We present a particle-in-cell simulation study of the steady-state interaction between two stationary dust grains in uniform stationary plasma. Both the electrostatic force and the shadowing force on the grains are calculated explicitly. The electrostatic force is always repulsive. For two grains of the same size, the electrostatic force is very nearly equal to the shielded electric field due to a single isolated grain, acting on the charge of the other grain. For two grains of unequal size, the electrostatic force on the smaller grain is smaller than the isolated-grain field, and the force on the larger grain is largermore » than the isolated-grain field. In all cases, the attractive shadowing force exceeds the repulsive electrostatic force when the grain separation d is greater than an equilibrium separation d{sub 0}. d{sub 0} is found to be between 6λ{sub D} and 9λ{sub D} in all cases. The binding energy is estimated to be between 19 eV and 900 eV for various cases.« less

Incorporation of whole, ancient grains into a modern Asian Indian diet to reduce the burden of chronic disease.

PubMed

Dixit, Anjali A; Azar, Kristen Mj; Gardner, Christopher D; Palaniappan, Latha P

2011-08-01

Refined carbohydrates, such as white rice and white flour, are the mainstay of the modern Asian Indian diet, and may contribute to the rising incidence of type 2 diabetes and cardiovascular disease in this population. Prior to the 1950s, whole grains such as amaranth, barley, brown rice, millet, and sorghum were more commonly used in Asian Indian cooking. These grains and other non-Indian grains such as couscous, quinoa, and spelt are nutritionally advantageous and may be culturally acceptable carbohydrate substitutes for Asian Indians. This review focuses on practical recommendations for culturally sensitive carbohydrate modification in a modern Asian Indian diet to reduce type 2 diabetes and cardiovascular disease in this population. © 2011 International Life Sciences Institute.

Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

NASA Astrophysics Data System (ADS)

Cavaliere, P.; Perrone, A.; Silvello, A.

2014-10-01

Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

Computer simulation of refining process of a high consistency disc refiner based on CFD

NASA Astrophysics Data System (ADS)

Wang, Ping; Yang, Jianwei; Wang, Jiahui

2017-08-01

In order to reduce refining energy consumption, the ANSYS CFX was used to simulate the refining process of a high consistency disc refiner. In the first it was assumed to be uniform Newton fluid of turbulent state in disc refiner with the k-ɛ flow model; then meshed grids and set the boundary conditions in 3-D model of the disc refiner; and then was simulated and analyzed; finally, the viscosity of the pulp were measured. The results show that the CFD method can be used to analyze the pressure and torque on the disc plate, so as to calculate the refining power, and streamlines and velocity vectors can also be observed. CFD simulation can optimize parameters of the bar and groove, which is of great significance to reduce the experimental cost and cycle.

Fabrication of ultra-fine grained aluminium tubes by RTES technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, H., E-mail: h.jafarzadeh@ut.ac.ir; Abrinia, K.

Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement ismore » determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.« less

BHQ revisited (1) - Looking at grain size

NASA Astrophysics Data System (ADS)

Heilbronner, Renée; Kilian, Rüdiger; Tullis, Jan

2016-04-01

Black Hills Quartzite (BHQ) has been used extensively in experimental rock deformation for numerous studies. Coaxial and general shear experiments have been carried out, for example, to define the dislocation creep regimes of quartz (Hirth & Tullis, 1992), to determine the effect of annealing (Heilbronner & Tullis, 2002) or to study the development of texture and microstructure with strain (Heilbronner & Tullis, 2006). BHQ was also used to determine the widely used quartz piezometer by Stipp & Tullis (2003). Among the microstructure analyses that were performed in those original papers, grain size was usually determined using CIP misorientation images. However, the CIP method (= computer-integrated polarization microscopy, details in Heilbronner and Barrett, 2014) is only capable of detecting the c-axis orientation of optically uniaxial materials and hence is only capable of detecting grain boundaries between grains that differ in c-axis orientation. One of the puzzling results we found (Heilbronner & Tullis, 2006) was that the recrystallized grain size seemed to depend on the crystallographic preferred orientation of the domain. In other words the grain size did not only depend on the flow stress but also on the orientation of the c-axis w/r to the shear direction. At the time, no EBSD analysis (electron back scatter diffraction) was carried out and hence the full crystallographic orientation was not known. In principle it is therefore possible that we missed some grain boundaries (between grains with parallel c-axes) and miscalculated our grain sizes. In the context of recent shear experiments on quartz gouge at the brittle-viscous transition (see Richter et al., this conference), where EBSD is used to measure the recrystallized grain size, we wanted to re-measure the CIP grain sizes of our 2006 samples (deformed in regime 1, 2 and 3 of dislocation) in exactly the same way. In two companion posters we use EBSD orientation imaging to repeat, refine and expand the

Uranium vacancy mobility at the Σ5 symmetric tilt and Σ5 twist grain boundaries in UO₂

DOE PAGES

Uberuaga, Blas Pedro; Andersson, David A.

2015-10-01

Ionic transport at grain boundaries in oxides dictates a number of important phenomena, from ionic conductivity to sintering to creep. For nuclear fuels, it also influences fission gas bubble nucleation and growth. Here, using a combination of atomistic calculations and object kinetic Monte Carlo (okMC) simulations, we examine the kinetic pathways associated with uranium vacancies at two model grain boundaries in UO 2. The barriers for vacancy motion were calculated using the nudged elastic band method at all uranium sites at each grain boundary and were used as the basis of the okMC simulations. For both boundaries considered – amore » simple tilt and a simple twist boundary – the mobility of uranium vacancies is significantly higher than in the bulk. For the tilt boundary, there is clearly preferred migration along the tilt axis as opposed to in the perpendicular direction while, for the twist boundary, migration is essentially isotropic within the boundary plane. These results show that cation defect mobility in fluorite-structured materials is enhanced at certain types of grain boundaries and is dependent on the boundary structure with the tilt boundary exhibiting higher rates of migration than the twist boundary.« less

Whole grain intake, determined by dietary records and plasma alkylresorcinol concentrations, is low among pregnant women in Singapore.

PubMed

Ross, Alastair B; Colega, Marjorelee T; Lim, Ai Lin; Silva-Zolezzi, Irma; Macé, Katherine; Saw, Seang Mei; Kwek, Kenneth; Gluckman, Peter; Godfrey, Keith M; Chong, Yap-Seng; Chong, Mary F F

2015-01-01

To quantify whole grain intake in pregnant women in Singapore in order to provide the first detailed analysis of whole grain intake in an Asian country and in pregnant women. Analysis of 24-h diet recalls in a cross-sectional cohort study and analysis of a biomarker of whole grain intake (plasma alkylresorcinols) in a subset of subjects. The Growing Up in Singapore Towards healthy Outcomes-mother offspring cohort study based in Singapore. 998 pregnant mothers with complete 24-h recalls taken during their 26-28th week of gestation. Plasma samples from a randomly select subset of 100 subjects were analysed for plasma alkylresorcinols. Median (IQR) whole grain intake for the cohort and the 30% who reported eating whole grains were 0 (IQR 0, 9) and 23.6 (IQR 14.6, 44.2) g/day respectively. Plasma alkylresorcinol concentrations were very low [median (IQR)=9 (3, 15) nmol/L], suggesting low intake of whole grain wheat in this population. Plasma alkylresorcinols were correlated with whole grain wheat intake (Spearman's r=0.35; p<0.01). Whole grain intake among pregnant mothers in Singapore was well below the 2-3 (60-95 g) servings of whole grains per day recommended by the Singapore Health Promotion Board. Efforts to increase whole grain intake should be supported to encourage people to choose whole grains over refined grains in their diet.

Evolution of grain boundary character distributions in alloy 825 tubes during high temperature annealing: Is grain boundary engineering achieved through recrystallization or grain growth?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Qin; Zhao, Qing

Grain boundary engineering (GBE) of nickel-based alloy 825 tubes was carried out with different cold drawing deformations by using a draw-bench on a factory production line and subsequent annealing at various temperatures. The microstructure evolution of alloy 825 during thermal-mechanical processing (TMP) was characterized by means of the electron backscatter diffraction (EBSD) technique to study the TMP effects on the grain boundary network and the evolution of grain boundary character distributions during high temperature annealing. The results showed that the proportion of ∑ 3{sup n} coincidence site lattice (CSL) boundaries of alloy 825 tubes could be increased to > 75%more » by the TMP of 5% cold drawing and subsequent annealing at 1050 °C for 10 min. The microstructures of the partially recrystallized samples and the fully recrystallized samples suggested that the proportion of low ∑ CSL grain boundaries depended on the annealing time. The frequency of low ∑ CSL grain boundaries increases rapidly with increasing annealing time associating with the formation of large-size highly-twinned grains-cluster microstructure during recrystallization. However, upon further increasing annealing time, the frequency of low ∑ CSL grain boundaries decreased markedly during grain growth. So it is concluded that grain boundary engineering is achieved through recrystallization rather than grain growth. - Highlights: •The grain boundary engineering (GBE) is applicable to 825 tubes. •GBE is achieved through recrystallization rather than grain growth. •The low ∑ CSL grain boundaries in 825 tubes can be increased to > 75%.« less

Effect of samarium in corrosion and microstructure of Al-5Zn-0.5Cu as low driving voltage sacrificial anode

NASA Astrophysics Data System (ADS)

Pratesa, Yudha; Ferdian, Deni; Ramadhan, Fajar Yusya; Maulana, Bramuda

2018-05-01

Sacrificial Anode Low voltage is the latest generation of the sacrificial anode that can prevent the occurrence of Hydrogen Cracking (HIC) due to overprotection. The Al-5n-0.5Cu alloy showed the potential to be developed as the new sacrificial anode. However, the main problem is copper made Al2Cu intermetallic in grain boundary. Samarium is added to modify the shape of the intermetallic to make it finer and make the corrosion uniform. Several characterizations were conducted to analyze the effect of Samarium. Scanning electron microscope (SEM) and Energy dispersive spectroscopy was used to analyzed the microstructure of the alloy. Metallography preparation was prepared for SEM analysis. Corrosion behavior was characterized by cyclic polarization in 3.5% NaCl solution. The results show samarium can change the shape of intermetallic and refine the grains. In addition, samarium makes better pitting resistance and exhibits a tendency for uniform corrosion. It is indicated by the loop reduction (ΔEpit-prot). Current density increased as an effect of samarium addition from 6x10-5 Ampere (Al-5Zn-0.5Cu) to 2.5x10-4 Ampere (Al-5Zn-0.5Cu-0.5Sm). Steel potential protection increased after addition of samarium which is an indication the possibility of Al-Zn-Cu-Sm to be used as low voltage sacrificial anode.

Strontium and barium isotopes in presolar silicon carbide grains measured with CHILI—two types of X grains

DOE PAGES

Stephan, Thomas; Trappitsch, Reto; Davis, Andrew M.; ...

2017-05-10

Here, we used CHILI, the Chicago Instrument for Laser Ionization, a new resonance ionization mass spectrometer developed for isotopic analysis of small samples, to analyze strontium, zirconium, and barium isotopes in 22 presolar silicon carbide grains. Twenty of the grains showed detectable strontium and barium, but none of the grains had enough zirconium to be detected with CHILI. Nine grains were excluded from further consideration since they showed very little signals (<1000 counts) for strontium as well as for barium. Among the 11 remaining grains, we found three X grains. The discovery of three supernova grains among only 22 grainsmore » was fortuitous, because only ~1% of presolar silicon carbide grains are type X, but was confirmed by silicon isotopic measurements of grain residues with NanoSIMS. And while one of the X grains showed strontium and barium isotope patterns expected for supernova grains, the two other supernova grains have 87Sr/86Sr < 0.5, values never observed in any natural sample before. From their silicon isotope ratios, the latter two grains can be classified as X2 grains, while the former grain belongs to the more common X1 group. The differences of these grains in strontium and barium isotopic composition constrain their individual formation conditions in Type II supernovae.« less

Strontium and barium isotopes in presolar silicon carbide grains measured with CHILI—two types of X grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephan, Thomas; Trappitsch, Reto; Davis, Andrew M.

Here, we used CHILI, the Chicago Instrument for Laser Ionization, a new resonance ionization mass spectrometer developed for isotopic analysis of small samples, to analyze strontium, zirconium, and barium isotopes in 22 presolar silicon carbide grains. Twenty of the grains showed detectable strontium and barium, but none of the grains had enough zirconium to be detected with CHILI. Nine grains were excluded from further consideration since they showed very little signals (<1000 counts) for strontium as well as for barium. Among the 11 remaining grains, we found three X grains. The discovery of three supernova grains among only 22 grainsmore » was fortuitous, because only ~1% of presolar silicon carbide grains are type X, but was confirmed by silicon isotopic measurements of grain residues with NanoSIMS. And while one of the X grains showed strontium and barium isotope patterns expected for supernova grains, the two other supernova grains have 87Sr/86Sr < 0.5, values never observed in any natural sample before. From their silicon isotope ratios, the latter two grains can be classified as X2 grains, while the former grain belongs to the more common X1 group. The differences of these grains in strontium and barium isotopic composition constrain their individual formation conditions in Type II supernovae.« less

Effect of Hypoeutectic Boron Additions on the Grain Size and Mechanical Properties of Ti-6Al-4V Manufactured with Powder Bed Electron Beam Additive Manufacturing

NASA Astrophysics Data System (ADS)

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; Wojcieszynski, Andrzej; Dehoff, Ryan; Nandwana, Peeyush; Horn, Timothy

2017-03-01

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricated Ti-6Al-4V + B indicate that the addition of 0.25-1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.

Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion.

PubMed

Temple, Norman J

2018-01-04

During the 1970s some investigators proposed that refined carbohydrates, especially sugar and a low intake of dietary fiber, were major factors in coronary heart disease (CHD). This suggestion was eclipsed by the belief that an excess intake of saturated fatty acids (SFA) was the key dietary factor, a view that prevailed from roughly 1974 to 2014. Findings that have accumulated since 1990 inform us that the role of SFA in the causation of CHD has been much exaggerated. A switch from SFA to refined carbohydrates does not lower the ratio of total cholesterol to HDL-cholesterol in the blood and therefore does not prevent CHD. A reduced intake of SFA combined with an increased intake of polyunsaturated fatty acids lowers the ratio of total cholesterol to HDL-cholesterol; this may reduce the risk of CHD. The evidence linking carbohydrate-rich foods with CHD has been steadily strengthening. Refined carbohydrates, especially sugar-sweetened beverages, increase the risk of CHD. Conversely, whole grains and cereal fiber are protective. An extra one or 2 servings per day of these foods increases or decreases risk by approximately 10% to 20%.

Development of ultrafine-grained microstructure in Al-Cu-Mg alloy through equal-channel angular pressing

NASA Astrophysics Data System (ADS)

Sai Anuhya, Danam; Gupta, Ashutosh; Nayan, Niraj; Narayana Murty, S. V. S.; Manna, R.; Sastry, G. V. S.

2014-08-01

Al-Cu-Mg alloys are extensively used for riveting applications in aerospace industries due to their relatively high shear strength coupled with high plasticity. The significant advantage of using V65 aluminum alloy ((Al-4Cu-0.2Mg) for rivet application also stems from its significantly slower natural aging kinetics, which gives operational flexibility to carryout riveting operation even after 4 days of solution heat treatment, in contrast to its equivalent alloy AA2024.Rivets are usually made by cold heading of wire rods. In order to form a defect free rivet head, grain size control in wire rods is essential at each and every stage of processing right from casting onwards upto the final wire drawing stage. Wire drawing is carried out at room temperature to reduce diameter as well as impart good surface finish. In the present study, different microstructures in V65 alloy bars were produced by rolling at different temperatures (room temperature to 523K) and subsequently deformed by equal channel angular pressing (ECAP) at 423K upto an equivalent strain of 7. ECAP was carried out to study the effect of initial microstructure on grain refinement and degree of deformation on the evolution of ultrafine grain structure. The refinement of V65 alloy by ECAP is significantly influenced by Initial microstructure but amount of deformation strongly affects the evolution processes as revealed by optical microscopy and transmission electron microscopy.

Titanium carbide particles as pre-solar grains

NASA Astrophysics Data System (ADS)

Kimura, Y.; Kaito, C.

2003-08-01

Focusing on the growth of metal carbide particles and the formation of pre-solar grains, a new attempt has been made for titanium carbide (TiC) systems. Using the noble gas evaporation method, we succeeded in producing TiC core (50-nm) carbon mantle (2-nm) grains of the same core size as pre-solar grains. The infrared spectrum has broad absorption features at 9.5 and 12.5 μm. It was also found that these absorption peaks became weaker by an increase to 15 nm of carbon mantle layer. The determination method of the contact angle of carbon on the TiC grain has been developed using a high-resolution electron microscopic technique. The contact angles between TiC and carbon were and on the (111) and (100) TiC grain surfaces, respectively.

Effect of Al Addition on Microstructure of AZ91D

NASA Astrophysics Data System (ADS)

Joshi, Utsavi; Babu, Nadendla Hari

Casting is a net shape or near net shape forming process so work-hardening will not be applicable for improving properties of magnesium cast alloys. Grain refinement, solid-solution strengthening, precipitation hardening and specially designed heat treatment are the techniques used to enhance the properties of these alloys. This research focusses on grain refinement of magnesium alloy AZ91D, which is a widely used commercial cast alloy. Recently, Al-B based master alloys have shown potential in grain refining AZ91D. A comparative study of the grain refinement of AZ91D by addition of 0.02wt%B, 0.04wt%B, 0.1wt%B, 0.5wt%B and 1.0wt%B of A1-5B master alloy and equivalent amount of solute element aluminium is described in this paper. Hardness profile of AZ91D alloyed with boron and aluminium is compared.

AC conductivity scaling behavior in grain and grain boundary response regime of fast lithium ionic conductors

NASA Astrophysics Data System (ADS)

Mariappan, C. R.

2014-05-01

AC conductivity spectra of Li-analogues NASICON-type Li1.5Al0.5Ge1.5P3O12 (LAGP), Li-Al-Ti-P-O (LATP) glass-ceramics and garnet-type Li7La2Ta2O13 (LLTO) ceramic are analyzed by universal power law and Summerfield scaling approaches. The activation energies and pre-exponential factors of total and grain conductivities are following the Meyer-Neldel (M-N) rule for NASICON-type materials. However, the garnet-type LLTO material deviates from the M-N rule line of NASICON-type materials. The frequency- and temperature-dependent conductivity spectra of LAGP and LLTO are superimposed by Summerfield scaling. The scaled conductivity curves of LATP are not superimposed at the grain boundary response region. The superimposed conductivity curves are observed at cross-over frequencies of grain boundary response region for LATP by incorporating the exp ( {{{ - (EAt - EAg )} {{{ - (EAt - EAg )} {kT}}} ) factor along with Summerfield scaling factors on the frequency axis, where EAt and EAg are the activation energies of total and grain conductivities, respectively.

Increased Night Temperature Negatively Affects Grain Yield, Biomass and Grain Number in Chilean Quinoa

PubMed Central

Lesjak, Jurka; Calderini, Daniel F.

2017-01-01

Quinoa high nutritive value increases interest worldwide, especially as a crop that could potentially feature in different cropping systems, however, climate change, particularly rising temperatures, challenges this and other crop species. Currently, only limited knowledge exists regarding the grain yield and other key traits response to higher temperatures of this crop, especially to increased night temperatures. In this context, the main objective of this study was to evaluate the effect of increased night temperature on quinoa yield, grain number, individual grain weight and processes involved in crop growth under the environmental conditions (control treatment) and night thermal increase at two phases: flowering (T1) and grain filling (T2) in southern Chile. A commercial genotype, Regalona, and a quinoa accession (Cod. BO5, N°191, grain bank from Semillas Baer, hereby referred to as Accession) were used, due to their adaptability to Southern Chilean conditions and contrasting grain yield potential, grain weight and size of plants. Temperature was increased ≈4°C above the ambient from 8 pm until 9 am the next morning. Control treatments reached a high grain yield (600 and 397 g m-2, i.e., Regalona and Accession). Temperature increase reduced grain yield by 31% under T1 treatment and 12% when under T2 in Regalona and 23 and 26% in Accession, respectively. Aboveground biomass was negatively affected by the thermal treatments and a positive linear association was found between grain yield and aboveground biomass across treatments. By contrast, the harvest index was unaffected either by genotype, or by thermal treatments. Grain number was significantly affected between treatments and this key trait was linearly associated with grain yield. On the other hand, grain weight showed a narrow range of variation across treatments. Additionally, leaf area index was not affected, but significant differences were found in SPAD values at the end of T1 treatment, compared

Levels of fungi and mycotoxins in the samples of grain and grain dust collected from five various cereal crops in eastern Poland.

PubMed

Krysińska-Traczyk, Ewa; Perkowski, Juliusz; Dutkiewicz, Jacek

2007-01-01

During combine harvesting of 5 various cereal crops (rye, barley, oats, buckwheat, corn) 24 samples of grain and 24 samples of settled grain dust were collected on farms located in the Lublin province of eastern Poland. The samples were examined for the concentration of total microfungi, Fusarium species, deoxynivalenol (DON), nivalenol (NIV), and ochratoxin A (OTA). Microfungi able to grow on malt agar were present in 79.2% of grain samples and in 91.7% of grain dust samples in the concentrations of 1.0-801.3x10(3) cfu/g and 1.5-12440.0x10(3) cfu/g, respectively. The concentration of microfungi in grain dust samples was significantly greater than in grain samples (p<0.01). Fusarium strains were isolated from 54.2% of grain samples and from 58.3% of grain dust samples in the concentrations of 0.1-375.0x10(3) cfu/g and 4.0-7,700.0x10(3) cfu/g, respectively. They were found in all samples of grain and grain dust from rye, barley and corn, but only in 0-16.7% of samples of grain and grain dust from oats and buckwheat. DON was found in 79.2% of grain samples and in 100% of grain dust samples in the concentrations of 0.001-0.18 microg/g and 0.006-0.283 microg/g, respectively. NIV was detected in 62.5% of grain samples and in 94.4% of grain dust samples in the concentrations of 0.004-0.502 microg/g and 0.005-0.339 microg/g, respectively. OTA was detected in 58.3% of grain samples and in 91.7% of grain dust samples in the concentrations of 0.00039- 0.00195 microg/g and 0.00036-0.00285 microg/g, respectively. The concentrations of DON, total fusariotoxins (DON+NIV) and OTA were significantly greater in grain dust samples than in grain samples (p<0.05, p<0.05, and p<0.001, respectively). The concentration of Fusarium poae in the samples of rye grain and dust was significantly correlated with the concentrations of DON (p<0.05), NIV (p<0.01), and total fusariotoxins (p<0.05). Similarly, the concentration of Fusarium culmorum in the samples of barley grain and dust was

Impact of high temperature stress on floret fertility and individual grain weight of grain sorghum: sensitive stages and thresholds for temperature and duration

PubMed Central

Prasad, P. V. V.; Djanaguiraman, Maduraimuthu; Perumal, Ramasamy; Ciampitti, Ignacio A.

2015-01-01

Sorghum [Sorghum bicolor (L.) Moench] yield formation is severely affected by high temperature stress during reproductive stages. This study pursues to (i) identify the growth stage(s) most sensitive to high temperature stress during reproductive development, (ii) determine threshold temperature and duration of high temperature stress that decreases floret fertility and individual grain weight, and (iii) quantify impact of high daytime temperature during floret development, flowering and grain filling on reproductive traits and grain yield under field conditions. Periods between 10 and 5 d before anthesis; and between 5 d before- and 5 d after-anthesis were most sensitive to high temperatures causing maximum decreases in floret fertility. Mean daily temperatures >25°C quadratically decreased floret fertility (reaching 0% at 37°C) when imposed at the start of panicle emergence. Temperatures ranging from 25 to 37°C quadratically decreased individual grain weight when imposed at the start of grain filling. Both floret fertility and individual grain weights decreased quadratically with increasing duration (0–35 d or 49 d during floret development or grain filling stage, respectively) of high temperature stress. In field conditions, imposition of temperature stress (using heat tents) during floret development or grain filling stage also decreased floret fertility, individual grain weight, and grain weight per panicle. PMID:26500664

Embrittlement of Intercritically Reheated Coarse Grain Heat-Affected Zone of ASTM4130 Steel

NASA Astrophysics Data System (ADS)

Li, Liying; Han, Tao; Han, Bin

2018-04-01

In this investigation, a thermal welding simulation technique was used to investigate the microstructures and mechanical properties of the intercritically reheated coarse grain heat-affected zone (IR CGHAZ) of ASTM4130 steel. The effect of post weld heat treatment (PWHT) on the toughness of IR CGHAZ was also analyzed. The toughness of IR CGHAZ was measured by means of Charpy impact, and it is found that IR CGHAZ has the lowest toughness which is much lower than that of the base metal regardless of whether PWHT is applied or not. The as-welded IR CGHAZ is mainly composed of ferrite, martensite, and many blocky M-A constituents distributing along grain boundaries and subgrain boundaries in a near-connected network. Also, the prior austenite grains are still as coarse as those in the coarse grain heat-affected zone (CGHAZ). The presence of the blocky M-A constituents and the coarsened austenite grains result in the toughness deterioration of the as-welded IR CGHAZ. Most of the blocky M-A constituents are decomposed to granular bainite due to the effect of the PWHT. However, PWHT cannot refine the prior austenite grains. Thus, the low toughness of IR CGHAZ after PWHT can be attributed to two factors, i.e., the coarsened austenite grains, and the presence of the remaining M-A constituents and granular bainite, which are located at grain boundaries and subgrain boundaries in a near-connected network. The absorbed energy of the IR CGHAZ was increased by about 3.75 times, which means that the PWHT can effectively improve the toughness but it cannot be recovered to the level of base metal.

Incorporation of Whole, Ancient Grains into a Modern Asian Indian Diet: Practical Strategies to Reduce the Burden of Chronic Disease

PubMed Central

Dixit, Anjali A.; Azar, Kristen M. J.; Gardner, Christopher D.; Palaniappan, Latha P.

2011-01-01

Refined carbohydrates, such as white rice and white flour, are the mainstay of the modern Asian Indian diet, and may contribute to the rising incidence of type 2 diabetes and cardiovascular disease in this population. Prior to the 1950s, whole grains such as amaranth, barley, brown rice, millet, and sorghum were more commonly used in Asian Indian cooking. These grains and other non-Indian grains such as couscous, quinoa, and spelt are nutritionally advantageous and may be culturally acceptable carbohydrate substitutes for Asian Indians. This review focuses on practical recommendations for culturally sensitive carbohydrate modification in a modern Asian Indian diet, in an effort to reduce type 2 diabetes and cardiovascular disease in this population. PMID:21790614

GalaxyRefineComplex: Refinement of protein-protein complex model structures driven by interface repacking.

PubMed

Heo, Lim; Lee, Hasup; Seok, Chaok

2016-08-18

Protein-protein docking methods have been widely used to gain an atomic-level understanding of protein interactions. However, docking methods that employ low-resolution energy functions are popular because of computational efficiency. Low-resolution docking tends to generate protein complex structures that are not fully optimized. GalaxyRefineComplex takes such low-resolution docking structures and refines them to improve model accuracy in terms of both interface contact and inter-protein orientation. This refinement method allows flexibility at the protein interface and in the overall docking structure to capture conformational changes that occur upon binding. Symmetric refinement is also provided for symmetric homo-complexes. This method was validated by refining models produced by available docking programs, including ZDOCK and M-ZDOCK, and was successfully applied to CAPRI targets in a blind fashion. An example of using the refinement method with an existing docking method for ligand binding mode prediction of a drug target is also presented. A web server that implements the method is freely available at http://galaxy.seoklab.org/refinecomplex.

Effects of Unfermented and Fermented Whole Grain Rye Crisp Breads Served as Part of a Standardized Breakfast, on Appetite and Postprandial Glucose and Insulin Responses: A Randomized Cross-over Trial

PubMed Central

Johansson, Daniel P; Lee, Isabella; Risérus, Ulf; Langton, Maud; Landberg, Rikard

2015-01-01

Background Whole grain rye products have been shown to increase satiety and elicit lower postprandial insulin response without a corresponding change in glucose response compared with soft refined wheat bread. The underlying mechanisms for these effects have not been fully determined The primary aim of the study was to investigate if whole grain rye crisp bread compared to refined wheat crisp bread, elected beneficial effects on appetite and postprandial insulin response, similarly as for other rye products. Methods In a randomized cross-over trial, 23 healthy volunteers, aged 27-70 years, BMI 18-31.4 kg/m2, were served a standardized breakfast with unfermented whole grain rye crisp bread (uRCB), fermented whole grain rye crisp bread (RCB) or refined wheat crisp bread (WCB), Appetite was measured using a visual analogue scale (VAS) until 4 h after breakfast. Postprandial glucose and insulin were measured at 0-230 min. Breads were chemically characterized including macronutrients, energy, dietary fiber components, and amino acid composition, and microstructure was characterized with light microscopy. Results Reported fullness was 16% higher (P<0.001), and hunger 11% and 12% lower (P<0.05) after ingestion of uRCB and RCB, respectively, compared with WCB. Postprandial glucose response did not differ significantly between treatments. Postprandial insulin was 10% lower (P<0.007) between 0-120 min but not significantly lower between 0-230 min for RCB compared with WCB. uRCB induced 13% (P<0.002) and 17% (P<0.001) lower postprandial insulin response between 0-230 min compared with RCB and WCB respectively. Conclusion Whole grain rye crisp bread induces higher satiety and lower insulin response compared with refined wheat crisp bread. Microstructural characteristics, dietary fiber content and composition are probable contributors to the increased satiety after ingestion of rye crisp breads. Higher insulin secretion after ingestion of RCB and WCB compared with uRCB may be

The Use of In Situ X-ray Imaging Methods in the Research and Development of Magnesium-Based Grain-Refined and Nanocomposite Materials

NASA Astrophysics Data System (ADS)

Sillekens, W. H.; Casari, D.; Mirihanage, W. U.; Terzi, S.; Mathiesen, R. H.; Salvo, L.; Daudin, R.; Lhuissier, P.; Guo, E.; Lee, P. D.

2016-12-01

Metallurgists have an ever-increasing suite of analytical techniques at their disposition. Among these techniques are the in situ methods, being those approaches that are designed to actually study events that occur in the material during for instance solidification, (thermo)-mechanical working or heat treatment. As such they are a powerful tool in unraveling the mechanisms behind these processes, supplementary to ex situ methods that instead analyze the materials before and after their processing. In this paper, case studies are presented of how in situ imaging methods—and more specifically micro-focus x-ray radiography and synchrotron x-ray tomography—are used in the research and development of magnesium-based grain-refined and nanocomposite materials. These results are drawn from the EC collaborative research project ExoMet (www.exomet-project.eu). The first example concerns the solidification of a Mg-Nd-Gd alloy with Zr addition to assess the role of zirconium content and cooling rate in crystal nucleation and growth. The second example concerns the solidification of a Mg-Zn-Al alloy and its SiC-containing nanocomposite material to reveal the influence of particle addition on microstructural development. The third example concerns the (partial) melting-solidification of Elektron21/AlN and Elektron21/Y2O3 nanocomposite materials to study such effects as particle pushing/engulfment and agglomeration during repeated processing. Such studies firstly visualize and by that confirm what is known or assumed. Secondly, they advance science by monitoring and quantifying phenomena as they evolve during processing and by that contribute toward a better understanding of the physics at play.

Effect of Different Thermomechanical Processes on the Microstructure, Texture, and Mechanical Properties of API 5L X70 Steel

NASA Astrophysics Data System (ADS)

Masoumi, Mohammad; Echeverri, Edwan Anderson Ariza; Silva, Cleiton Carvalho; Béreš, Miloslav; de Abreu, Hamilton Ferreira Gomes

2018-03-01

A commercial API 5L X70 steel plate was subjected to different thermomechanical processes to propose a novel thermomechanical rolling path to achieve improved mechanical properties. Scanning electron microscopy, electron backscatter diffraction, and x-ray texture analysis were employed for microstructural characterization. The results showed that strain-free recrystallized {001} ferrite grains that developed at higher rolling temperature could not meet the American Petroleum Institute (API) requirements. Also, refined and work-hardened grains that have formed in the intercritical region with high stored energy do not provide suitable tensile properties. However, fine martensite-austenite constituents dispersed in ferrite matrix with grains having predominantly {111} and {110} orientations parallel to the normal direction that developed under isothermal rolling at 850 °C provided an outstanding combination of tensile strength and ductility.

Quantum group spin nets: Refinement limit and relation to spin foams

NASA Astrophysics Data System (ADS)

Dittrich, Bianca; Martin-Benito, Mercedes; Steinhaus, Sebastian

2014-07-01

So far spin foam models are hardly understood beyond a few of their basic building blocks. To make progress on this question, we define analogue spin foam models, so-called "spin nets," for quantum groups SU(2)k and examine their effective continuum dynamics via tensor network renormalization. In the refinement limit of this coarse-graining procedure, we find a vast nontrivial fixed-point structure beyond the degenerate and the BF phase. In comparison to previous work, we use fixed-point intertwiners, inspired by Reisenberger's construction principle [M. P. Reisenberger, J. Math. Phys. (N.Y.) 40, 2046 (1999)] and the recent work [B. Dittrich and W. Kaminski, arXiv:1311.1798], as the initial parametrization. In this new parametrization fine-tuning is not required in order to flow to these new fixed points. Encouragingly, each fixed point has an associated extended phase, which allows for the study of phase transitions in the future. Finally we also present an interpretation of spin nets in terms of melonic spin foams. The coarse-graining flow of spin nets can thus be interpreted as describing the effective coupling between two spin foam vertices or space time atoms.

Influence of grain size and texture prior to warm rolling on microstructure, texture and magnetic properties of Fe-6.5 wt% Si steel

NASA Astrophysics Data System (ADS)

Xu, H. J.; Xu, Y. B.; Jiao, H. T.; Cheng, S. F.; Misra, R. D. K.; Li, J. P.

2018-05-01

Fe-6.5 wt% Si steel hot bands with different initial grain size and texture were obtained through different annealing treatment. These bands were then warm rolled and annealed. An analysis on the evolution of microstructure and texture, particularly the formation of recrystallization texture was studied. The results indicated that initial grain size and texture had a significant effect on texture evolution and magnetic properties. Large initial grains led to coarse deformed grains with dense and long shear bands after warm rolling. Such long shear bands resulted in growth advantage for {1 1 3} 〈3 6 1〉 oriented grains during recrystallization. On the other hand, sharp {11 h} 〈1, 2, 1/h〉 (α∗-fiber) texture in the coarse-grained sample led to dominant {1 1 2} 〈1 1 0〉 texture after warm rolling. Such {1 1 2} 〈1 1 0〉 deformed grains provided massive nucleation sites for {1 1 3} 〈3 6 1〉 oriented grains during subsequent recrystallization. These {1 1 3} 〈3 6 1〉 grains were confirmed to exhibit an advantage on grain growth compared to γ-fiber grains. As a result, significant {1 1 3} 〈3 6 1〉 texture was developed and unfavorable γ-fiber texture was inhibited in the final annealed sheet. Both these aspects led to superior magnetic properties in the sample with largest initial grain size. The magnetic induction B8 was 1.36 T and the high frequency core loss P10/400 was 17.07 W/kg.

Abnormal grain growth in iron-silicon

NASA Astrophysics Data System (ADS)

Bennett, Tricia A.

Abnormal grain growth (AGG) was studied in an Fe-1%Si alloy using automated Electron Backscattered Diffraction (EBSD) to determine the driving force for this phenomenon. Experiments were performed with the knowledge that there are several possible driving forces and, the intent to determine the true driving force by elimination of the other potential candidates. These potential candidates include surface energy anisotropy, anisotropic grain boundary properties and the stored energy of deformation. In this work, surface energy and grain boundary anisotropies as well as the stored energy of deformation were investigated as the possible driving forces for AGG. Accordingly, industrially processed samples that were temper rolled to 1.5% and 8% were annealed in air for various times followed by quenching in water. The results obtained were compared to those from heat treatments performed in wet 15%H2-85%N2 at a US Steel facility. In addition, for a more complete study of the effect of surface energy anisotropies on AGG, the 1.5% temper-rolled material was heat-treated in other atmospheres such as 5%H2-95%Ar, 98%H2-2%He, 98%H2-2%H 2S, and 98%H2-2%N2 for 1 hour followed by quenching in water. The character of the grain boundaries in the materials was also examined for each set of experiments conducted, while the influence of stored energy was evaluated by examining intragranular orientation gradients. AGG occurred regardless of annealing atmosphere though the most rapid progression was observed in samples annealed in air. In general, grains of varying orientations grew abnormally. One consistently observed trend in all the detailed studies was that the matrix grains remained essentially static and either did not grow or only grew very slowly. On the other hand, the abnormally large grains (ALG), on average, were approximately 10 times the size of the matrix. Analysis of the grain boundary character of the interfaces between abnormal grains and the matrix showed no

Crystal grain growth at the α -uranium phase transformation in praseodymium

NASA Astrophysics Data System (ADS)

Cunningham, Nicholas C.; Velisavljevic, Nenad; Vohra, Yogesh K.

2005-01-01

Structural phase transformations under pressure are examined in praseodymium metal for the range 0-40GPa at ambient temperature. Pressure was generated with a diamond-anvil cell, and data were collected using high-resolution synchrotron x-ray diffraction and the image plate technique. The structural sequence double hexagonal close packed (dhcp)→face centered cubic (fcc)→distorted-fcc (d-fcc)→ α -uranium (α-U) is observed with increasing pressure. Rietveld refinement of all crystallographic phases provided confirmation of the hR24 structure for the d-fcc phase while the previously reported monoclinic phase between the d-fcc and the α-U phase was not confirmed. We observe dramatic crystal grain growth during the volume collapse concurrent with the symmetry-lowering transition to the α-U structure. No preferred orientation axis is observed, and the formation process for these large grains is expected to be via a nucleation and growth mechanism. An analogous effect in rare earth metal cerium suggests that the grain growth during transformation to the α-U structure is a common occurrence in f -electron metals at high pressures.

Effect of alumina on grain refinement of Al-Si hypereutectic alloys

NASA Astrophysics Data System (ADS)

Majhi, J.; Sahoo, S. K.; Patnaik, S. C.; Sarangi, B.; Sachan, N. K.

2018-03-01

The size, volume fraction and distribution of primary as well as eutectic silicon affect the mechanical properties of the Al-Si hypereutectic alloys. It is very difficult for the simultaneous refinement and modification of primary and secondary Si particles in hypereutectic Al-Si alloys through traditional processes. This paper explores the role of γ-Al2O3 nanoparticles on Si particles in the course of solidification in hypereutectic Al-Si alloys at particular pouring temperature. The present study involves incorporation of varying contents dispersed γ-Al2O3 nanoparticles into a molten base metal during stir casting and followed by solidification. It has been reported that the synthesized composites having good interfacial bonding (wetting) between the dispersed phase and the liquid matrix was achieved in order to provide improved mechanical properties of the composite. The cast product of hypereutectic Al-16Si alloy with the reinforcement of nanoparticles, illustrated a significant improvement in both wear behaviour and hardness. The dry sliding wear test has been performed on a group of specimens with varying parameters (different loads and sliding velocities) in a pin on disc wear testing machine. Moreover, the wear rate and specific wear rate also affected in different load and different sliding velocities. However in XRD analysis of the samples, the enhancement of wear resistance as well as hardness was due to the formation of brittle phases like SiO2, Al2O3 and Al-rich intermetallic compounds. The hardness value of the materials increases nearly 6% in addition to increase in the density of only 0.8%. As per literature, the large plate eutectic Si particles were modified in to the fine core particles and it acquires enough potential for various applications.

Substituting whole grains for refined grains in a 6-wk randomized trial has a modest effect on gut microbiota and immune and inflammatory markers of healthy adults

USDA-ARS?s Scientific Manuscript database

Background: Observational studies suggest an inverse association between whole-grain (WG) consumption and inflammation. However, evidence from interventional studies is limited, and few studies have included measurements of cell-mediated immunity. Objective: We assessed the effects of diets rich in ...

Grain size-sensitive creep in ice II

USGS Publications Warehouse

Kubo, T.; Durham, W.B.; Stern, L.A.; Kirby, S.H.

2006-01-01

Rheological experiments on fine-grained water ice II at low strain rates reveal a creep mechanism that dominates at conditions of low stress. Using cryogenic scanning electron microscopy, we observed that a change in stress exponent from 5 to 2.5 correlates strongly with a decrease in grain size from about 40 to 6 micrometers. The grain size-sensitive creep of ice II demonstrated here plausibly dominates plastic strain at the low-stress conditions in the interior of medium- to large-sized icy moons of the outer solar system.

Grain size-sensitive creep in ice II.

PubMed

Kubo, Tomoaki; Durham, William B; Stern, Laura A; Kirby, Stephen H

2006-03-03

Rheological experiments on fine-grained water ice II at low strain rates reveal a creep mechanism that dominates at conditions of low stress. Using cryogenic scanning electron microscopy, we observed that a change in stress exponent from 5 to 2.5 correlates strongly with a decrease in grain size from about 40 to 6 micrometers. The grain size-sensitive creep of ice II demonstrated here plausibly dominates plastic strain at the low-stress conditions in the interior of medium- to large-sized icy moons of the outer solar system.

Magnetic losses reduction in grain oriented silicon steel by pulse and continuous fiber laser processing

NASA Astrophysics Data System (ADS)

Petryshynets, Ivan; Kováč, František; Puchý, Viktor; Šebek, Martin; Füzer, Ján; Kollár, Peter

2018-04-01

The present paper shows the impact of different laser scribing conditions on possible reduction of magnetic losses in grain oriented electrical steel sheets. The experimental Fe-3%Si steel was taken from industrial line after final box annealing. The surface of investigated steel was subjected to fiber laser processing using both pulse and continuous scribing regimes in order to generate residual thermal stresses inducing the magnetic domains structure refinement. The magnetic losses of experimental samples before and after individual laser scribing regimes were tested in AC magnetic field with 50Hz frequency and induction of 1.5T. The most significant magnetic losses reduction of 38% was obtained at optimized conditions of continuous laser scribing regime. A semi quantitative relationship has been found between the domain patterns and the used fiber laser processing.

Atomic modeling of cryo-electron microscopy reconstructions--joint refinement of model and imaging parameters.

PubMed

Chapman, Michael S; Trzynka, Andrew; Chapman, Brynmor K

2013-04-01

When refining the fit of component atomic structures into electron microscopic reconstructions, use of a resolution-dependent atomic density function makes it possible to jointly optimize the atomic model and imaging parameters of the microscope. Atomic density is calculated by one-dimensional Fourier transform of atomic form factors convoluted with a microscope envelope correction and a low-pass filter, allowing refinement of imaging parameters such as resolution, by optimizing the agreement of calculated and experimental maps. A similar approach allows refinement of atomic displacement parameters, providing indications of molecular flexibility even at low resolution. A modest improvement in atomic coordinates is possible following optimization of these additional parameters. Methods have been implemented in a Python program that can be used in stand-alone mode for rigid-group refinement, or embedded in other optimizers for flexible refinement with stereochemical restraints. The approach is demonstrated with refinements of virus and chaperonin structures at resolutions of 9 through 4.5 Å, representing regimes where rigid-group and fully flexible parameterizations are appropriate. Through comparisons to known crystal structures, flexible fitting by RSRef is shown to be an improvement relative to other methods and to generate models with all-atom rms accuracies of 1.5-2.5 Å at resolutions of 4.5-6 Å. Copyright © 2013 Elsevier Inc. All rights reserved.

The Search for Interstellar Sulfide Grains

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.; Messenger, Scott

2010-01-01

The lifecycle of sulfur in the galaxy is poorly understood. Fe-sulfide grains are abundant in early solar system materials (e.g. meteorites and comets) and S is highly depleted from the gas phase in cold, dense molecular cloud environments. In stark contrast, sulfur is essentially undepleted from the gas phase in the diffuse interstellar medium, indicating that little sulfur is incorporated into solid grains in this environment. It is widely believed that sulfur is not a component of interstellar dust grains. This is a rather puzzling observation unless Fe-sulfides are not produced in significant quantities in stellar outflows, or their lifetime in the ISM is very short due to rapid destruction. Fe sulfide grains are ubiquitous in cometary samples where they are the dominant host of sulfur. The Fe-sulfides (primarily pyrrhotite; Fe(1-x)S) are common, both as discrete 0.5-10 micron-sized grains and as fine (5-10 nm) nanophase inclusions within amorphous silicate grains. Cometary dust particles contain high abundances of well-preserved presolar silicates and organic matter and we have suggested that they should contain presolar sulfides as well. This hypothesis is supported by the observation of abundant Fe-sulfides grains in dust around pre- and post-main sequence stars inferred from astronomical spectra showing a broad 23 micron IR feature due to FeS. Fe-sulfide grains also occur as inclusions in bona fide circumstellar amorphous silicate grains and as inclusions within deuterium-rich organic matter in cometary dust samples. Our irradiation experiments show that FeS is far more resistant to radiation damage than silicates. Consequently, we expect that Fe sulfide stardust should be as abundant as silicate stardust in solar system materials.

Fabrication of fine-grain tantalum diffusion barrier tube for Nb3Sn conductors

NASA Astrophysics Data System (ADS)

Hartwig, K. T.; Balachandran, S.; Mezyenski, R.; Seymour, N.; Robinson, J.; Barber, R. E.

2014-01-01

Diffusion barriers used in Nb3Sn wire are often fabricated by wrapping Ta sheet into a tube with an overlap seam. A common result of such practice is non-uniform deformation in the Ta sheet as it thins by wire drawing because of non-uniform grain size and texture in the original Ta sheet. Seamless Ta tube with a fine-grain and uniform microstructure would be much better for the diffusion barrier application, but such material is expensive and difficult to manufacture. This report presents results on a new fabrication strategy for Ta tube that shows promise for manufacture of less costly tube with an improved microstructure. The fabrication method begins with seam-welded tube but gives a fine-grain uniform microstructure with little difference between the longitudinal seam weld region and the parent metal after post-weld processing. Severe plastic deformation processing (SPD) applied by area reduction extrusion and tube equal channel angular extrusion (tECAE) are used to refine and homogenize the microstructure. Microstructure and mechanical property results are presented for Ta tubes fabricated by this new processing strategy.

Exposure to grain dust and microbial components in the Norwegian grain and compound feed industry.

PubMed

Halstensen, Anne Straumfors; Heldal, Kari Kulvik; Wouters, Inge M; Skogstad, Marit; Ellingsen, Dag G; Eduard, Wijnand

2013-11-01

The aim of this study was to extensively characterize grain workers' personal exposure during work in Norwegian grain elevators and compound feed mills, to identify differences in exposures between the workplaces and seasons, and to study the correlations between different microbial components. Samples of airborne dust (n = 166) were collected by full-shift personal sampling during work in 20 grain elevators and compound feed mills during one autumn season and two winter seasons. The personal exposure to grain dust, endotoxins, β-1→3-glucans, bacteria, and fungal spores was quantified. Correlations between dust and microbial components and differences between workplaces and seasons were investigated. Determinants of endotoxin and β-1→3-glucan exposure were evaluated by linear mixed-effect regression modeling. The workers were exposed to an overall geometric mean of 1.0mg m(-3) inhalable grain dust [geometric standard deviation (GSD) = 3.7], 628 endotoxin units m(-3) (GSD = 5.9), 7.4 µg m(-3) of β-1→3-glucan (GSD = 5.6), 21 × 10(4) bacteria m(-3) (GSD = 7.9) and 3.6 × 10(4) fungal spores m(-3) (GSD = 3.4). The grain dust exposure levels were similar across workplaces and seasons, but the microbial content of the grain dust varied substantially between workplaces. Exposure levels of all microbial components were significantly higher in grain elevators compared with all other workplaces. The grain dust exposure was significantly correlated (Pearson's r) with endotoxin (rp = 0.65), β-1→3-glucan (rp = 0.72), bacteria (rp = 0.44) and fungal spore (rp = 0.48) exposure, whereas the explained variances were strongly dependent on the workplace. Bacteria, grain dust, and workplace were important determinants for endotoxin exposure, whereas fungal spores, grain dust, and workplace were important determinants for β-1→3-glucan exposure. Although the workers were exposed to a relatively low mean dust level, the microbial exposure was high. Furthermore, the

Effect of hypoeutectic boron additions on the grain size and mechanical properties of Ti-6Al-4V manufactured with powder bed electron beam additive manufacturing

DOE PAGES

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; ...

2016-12-02

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricatedmore » Ti-6Al-4V + B indicate that the addition of 0.25–1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Furthermore, despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.« less

Effect of hypoeutectic boron additions on the grain size and mechanical properties of Ti-6Al-4V manufactured with powder bed electron beam additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricatedmore » Ti-6Al-4V + B indicate that the addition of 0.25–1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Furthermore, despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.« less

Film grain synthesis and its application to re-graining

NASA Astrophysics Data System (ADS)

Schallauer, Peter; Mörzinger, Roland

2006-01-01

Digital film restoration and special effects compositing require more and more automatic procedures for movie regraining. Missing or inhomogeneous grain decreases perceived quality. For the purpose of grain synthesis an existing texture synthesis algorithm has been evaluated and optimized. We show that this algorithm can produce synthetic grain which is perceptually similar to a given grain template, which has high spatial and temporal variation and which can be applied to multi-spectral images. Furthermore a re-grain application framework is proposed, which synthesises based on an input grain template artificial grain and composites this together with the original image content. Due to its modular approach this framework supports manual as well as automatic re-graining applications. Two example applications are presented, one for re-graining an entire movie and one for fully automatic re-graining of image regions produced by restoration algorithms. Low computational cost of the proposed algorithms allows application in industrial grade software.

Creep of quartz by dislocation and grain boundary processes

NASA Astrophysics Data System (ADS)

Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

2015-12-01

Wet polycrystalline quartz aggregates deformed at temperatures T of 600°-900°C and strain rates of 10-4-10-6 s-1 at a confining pressure Pc of 1.5 GPa exhibit plasticity at low T, governed by dislocation glide and limited recovery, and grain size-sensitive creep at high T, governed by diffusion and sliding at grain boundaries. Quartz aggregates were HIP-synthesized, subjecting natural milky quartz powder to T=900°C and Pc=1.5 GPa, and grain sizes (2 to 25 mm) were varied by annealing at these conditions for up to 10 days. Infrared absorption spectra exhibit a broad OH band at 3400 cm-1 due to molecular water inclusions with a calculated OH content (~4000 ppm, H/106Si) that is unchanged by deformation. Rate-stepping experiments reveal different stress-strain rate functions at different temperatures and grain sizes, which correspond to differing stress-temperature sensitivities. At 600-700°C and grain sizes of 5-10 mm, flow law parameters compare favorably with those for basal plasticity and dislocation creep of wet quartzites (effective stress exponents n of 3 to 6 and activation enthalpy H* ~150 kJ/mol). Deformed samples show undulatory extinction, limited recrystallization, and c-axis maxima parallel to the shortening direction. Similarly fine-grained samples deformed at 800°-900°C exhibit flow parameters n=1.3-2.0 and H*=135-200 kJ/mol corresponding to grain size-sensitive Newtonian creep. Deformed samples show some undulatory extinction and grain sizes change by recrystallization; however, grain boundary deformation processes are indicated by the low value of n. Our experimental results for grain size-sensitive creep can be compared with models of grain boundary diffusion and grain boundary sliding using measured rates of silicon grain boundary diffusion. While many quartz mylonites show microstructural and textural evidence for dislocation creep, results for grain size-sensitive creep may apply to very fine-grained (<10 mm) quartz mylonites.

Influence of Al content on the corrosion resistance of micro-alloyed hot rolled steel as a function of grain size

NASA Astrophysics Data System (ADS)

Qaban, Abdullah; Naher, Sumsun

2018-05-01

High-strength low-alloy steel (HSLA) has been widely used in many applications involving automobiles, aerospace, construction, and oil and gas pipelines due to their enhanced mechanical and chemical properties. One of the most critical elements used to improve these properties is Aluminium. This work will explore the effect of Al content on the corrosion behaviour of hot rolled high-strength low-alloy steel as a function of grain size. The method of investigation employed was weight loss technique. It was obvious that the increase in Al content enhanced corrosion resistance through refinement of grain size obtained through AlN precipitation by pinning grain boundaries and hindering their growth during solidification which was found to be beneficial in reducing corrosion rate.

The size distribution of interstellar grains

NASA Technical Reports Server (NTRS)

Witt, Adolf N.

1987-01-01

Three major areas involving interstellar grains were investigated. First, studies were performed of scattering in reflection nebulae with the goal of deriving scattering characteristics of dust grains such as the albedo and the phase function asymmetry throughout the visible and the ultraviolet. Secondly, studies were performed of the wavelength dependence of interstellar extinction designed to demonstrate the wide range of grain size distributions naturally occurring in individual clouds in different parts of the galaxy. And thirdly, studies were also performed of the ultraviolet powered emission of dust grains in the 0.5 to 1.0 micron wavelength range in reflection nebulae. Findings considered of major importance are highlighted.

Neodymium Isotope Variability at the Grain Scale in the Sub-Continental Lithospheric Mantle: NdO+ Analyses of Individual Clinopyroxene Grains (<5 ng Nd aliquots) from a Kilbourne Hole Harzburgitic Xenolith.

NASA Astrophysics Data System (ADS)

Harvey, J.; Honn, D.; Baxter, E. F.; Warren, J. M.; Hammond, S.; Walshaw, R.

2014-12-01

It is evident that at scales of 102 to 10-2 m there is significant isotopic heterogeneity in the mantle that is not always reflected in primitive melts. The "Os isotopic gap"[1] is one such manifestation of this phenomenon but a similar offset exists between the Nd isotope composition of abyssal peridotites and the mid-ocean ridge basalts that they are inferred to have produced[2]. This study takes advantage of recent advances in the analysis of Nd isotopes as NdO+[3,4] which permit the precise analysis of single clinopyroxene grains (<1 mg mass; <5 ng Nd) from a continental harzburgitic xenolith from Kilbourne Hole, NM. Analyses of aggregates of clinopyroxenes from 5 Kilbourne Hole xenoliths reveal a wide range of 143Nd/144Nd (0.513011 ± 28 to 0.513615 ±19)[5]. This study demonstrates significant grain-to-grain isotopic heterogeneity at a scale of 10-2 m (143Nd/144Nd = 0.513089 ± 78 to 0.513364 ± 74) which (i) is equivalent to the range of values for Pacific MORB[6] and (ii) is more primitive than local basalts with an asthenospheric signature[7]. This suggests that small-scale refractory domains exist within the mantle which are either not sampled during partial melting or whose presence is obscured by the melting of higher volumes of more fusible material. Ref:[1]Alard et al. (2005) Nature 436, 1005-1008 [2]Warren et al. (2009) JGR 114, B12203, doi:10.1029/2008JB006186 [3]Harvey and Baxter (2009) Chem. Geol. 258, 251-257 [4]Honn et al. (2013) AGU Fall abstr. V33-2722 [5]Harvey et al. (2012) J. Petrol. 53, 1709-1742 [6]Hofmann (1997) Nature 385, 219-229 [7]Thompson et al. (2005) J. Petrol. 46, 1603-1643

Refined composite multivariate generalized multiscale fuzzy entropy: A tool for complexity analysis of multichannel signals

NASA Astrophysics Data System (ADS)

Azami, Hamed; Escudero, Javier

2017-01-01

Multiscale entropy (MSE) is an appealing tool to characterize the complexity of time series over multiple temporal scales. Recent developments in the field have tried to extend the MSE technique in different ways. Building on these trends, we propose the so-called refined composite multivariate multiscale fuzzy entropy (RCmvMFE) whose coarse-graining step uses variance (RCmvMFEσ2) or mean (RCmvMFEμ). We investigate the behavior of these multivariate methods on multichannel white Gaussian and 1/ f noise signals, and two publicly available biomedical recordings. Our simulations demonstrate that RCmvMFEσ2 and RCmvMFEμ lead to more stable results and are less sensitive to the signals' length in comparison with the other existing multivariate multiscale entropy-based methods. The classification results also show that using both the variance and mean in the coarse-graining step offers complexity profiles with complementary information for biomedical signal analysis. We also made freely available all the Matlab codes used in this paper.

Effect of Melt Convection and Solid Transport on Macrosegregation and Grain Structure in Equiaxed Al-Cu Alloys

NASA Technical Reports Server (NTRS)

Rerko, Rodney S.; deGroh, Henry C., III; Beckermann, Christoph; Gray, Hugh R. (Technical Monitor)

2002-01-01

Macrosegregation in metal casting can be caused by thermal and solutal melt convection, and the transport of unattached solid crystals. These free grains can be a result of, for example, nucleation in the bulk liquid or dendrite fragmentation. In an effort to develop a comprehensive numerical model for the casting of alloys, an experimental study has been conducted to generate benchmark data with which such a solidification model could be tested. The specific goal of the experiments was to examine equiaxed solidification in situations where sinking of grains is (and is not) expected. The objectives were: 1) experimentally study the effects of solid transport and thermosolutal convection on macrosegregation and grain size distribution patterns; and 2) provide a complete set of controlled thermal boundary conditions, temperature data, segregation data, and grain size data, to validate numerical codes. The alloys used were Al-1 wt. pct. Cu, and Al-10 wt. pct. Cu with various amounts of the grain refiner TiB2 added. Cylindrical samples were either cooled from the top, or the bottom. Several trends in the data stand out. In attempting to model these experiments, concentrating on experiments that show clear trends or differences is recommended.

Survival of carbon grains in shocks

NASA Technical Reports Server (NTRS)

Seab, C. Gregory

1990-01-01

Supernova shocks play a significant part in the life of an interstellar grain. In a typical 10 to the 9th power year lifetime, a grain will be hit by an average of 10 shocks of 100 km s(sup -1) or greater velocity, and even more shocks of lower velocity. Evaluation of the results of this frequent shock processing is complicated by a number of uncertainties, but seems to give about 10 percent destruction of silicate grains and about half that for graphite grains. Because of the frequency of shocking, the mineralogy and sizes of the grain population is predominately determined by shock processing effects, and not by the initial grain nucleation and growth environment. One consequence of the significant role played by interstellar shocks is that a certain fraction (up to 5 percent) of the carbon should be transformed into the diamond phase. Diamond transformation is observed in the laboratory at threshold shock pressures easily obtainable in grain-grain collisions in supernova shocks. Yields for transforming graphite, amorphous carbon, glassy carbon, and other nearly pure carbon solids into diamond are quite high. Impurities up to at least the 10 percent level (for oxygen) are tolerated in the process. The typical size diamond expected from shock transformation agrees well with the observed sizes in the Lewis et al. findings in meteoritic material. Isotropic anomalies already contained in the grain are likely to be retained through the conversion process, while others may be implanted by the shock if the grain is close to the supernova. The meteoritic diamonds are likely to be the results of transformation of carbon grains in grain-grain collisions in supernova shock waves.

Effect of initial grain size on inhomogeneous plastic deformation and twinning behavior in high manganese austenitic steel with a polycrystalline microstructure

NASA Astrophysics Data System (ADS)

Ueji, R.; Tsuchida, N.; Harada, K.; Takaki, K.; Fujii, H.

2015-08-01

The grain size effect on the deformation twinning in a high manganese austenitic steel which is so-called TWIP (twining induced plastic deformation) steel was studied in order to understand how to control deformation twinning. The 31wt%Mn-3%Al-3% Si steel was cold rolled and annealed at various temperatures to obtain fully recrystallized structures with different mean grain sizes. These annealed sheets were examined by room temperature tensile tests at a strain rate of 10-4/s. The coarse grained sample (grain size: 49.6μm) showed many deformation twins and the deformation twinning was preferentially found in the grains in which the tensile axis is parallel near to [111]. On the other hand, the sample with finer grains (1.8 μm) had few grains with twinning even after the tensile deformation. The electron back scattering diffraction (EB SD) measurements clarified the relationship between the anisotropy of deformation twinning and that of inhomogeneous plastic deformation. Based on the EBSD analysis, the mechanism of the suppression of deformation twinning by grain refinement was discussed with the concept of the slip pattern competition between the slip system governed by a grain boundary and that activated by the macroscopic load.

The influence of grain size and composition on 1000 to 1400 K slow plastic flow properties of NiAl

NASA Technical Reports Server (NTRS)

Whittenberger, J. Daniel

1988-01-01

The compressive slow plastic flow behavior of several B2 crystal structure NiAl intermetallics has been studied in air between 1000 and 1400 K. Small grain-sized Ni-48.25 at. pct Al (of about 10 microns) was found to be stronger than the previously studied 17 microns diameter material. While grain refinement improved the strength at all test temperatures, the exact mechanism is not clear. Experiments at lower temperature revealed that composition as well as grain size can be an important factor, since Ni-49.2Al was weaker than Ni-48.25Al. Pronounced yield points were found during slow strain-rate testing at 1000 K; however, continued deformation appears to take place by the same mechanism(s) as found at high temperatures. Small changes in thermomechanical processing (TMP) schedules to fabricate Ni-49.2Al indicated that basic deformation characteristics (stress exponent and activation energy) are not affected; however, the preexponential term could be modified if TMP alters the grain structure.

Thermal conductivity in Bi0.5Sb1.5Te3+x and the role of dense dislocation arrays at grain boundaries.

PubMed

Deng, Rigui; Su, Xianli; Zheng, Zheng; Liu, Wei; Yan, Yonggao; Zhang, Qingjie; Dravid, Vinayak P; Uher, Ctirad; Kanatzidis, Mercouri G; Tang, Xinfeng

2018-06-01

Several prominent mechanisms for reduction in thermal conductivity have been shown in recent years to improve the figure of merit for thermoelectric materials. Such a mechanism is a hierarchical all-length-scale architecturing that recognizes the role of all microstructure elements, from atomic to nano to microscales, in reducing (lattice) thermal conductivity. In this context, there have been recent claims of remarkably low (lattice) thermal conductivity in Bi 0.5 Sb 1.5 Te 3 that are attributed to seemingly ordinary grain boundary dislocation networks. These high densities of dislocation networks in Bi 0.5 Sb 1.5 Te 3 were generated via unconventional materials processing with excess Te (which formed liquid phase, thereby facilitating sintering), followed by spark plasma sintering under pressure to squeeze out the liquid. We reproduced a practically identical microstructure, following practically identical processing strategies, but with noticeably different (higher) thermal conductivity than that claimed before. We show that the resultant microstructure is anisotropic, with notable difference of thermal and charge transport properties across and along two orthonormal directions, analogous to anisotropic crystals. Thus, we believe that grain boundary dislocation networks are not the primary cause of enhanced ZT through reduction in thermal conductivity. Instead, we can reproduce the purported high ZT through a favorable but impractical and incorrect combination of thermal conductivity measured along the pressing direction of anisotropy while charge transport measured in the direction perpendicular to the anisotropic direction. We believe that our work underscores the need for consistency in charge and thermal transport measurements for unified and verifiable measurements of thermoelectric (and related) properties and phenomena.

Effect of Al–5Ti–C Master Alloy on the Microstructure and Mechanical Properties of Hypereutectic Al–20%Si Alloy

PubMed Central

Ding, Wanwu; Xia, Tiandong; Zhao, Wenjun; Xu, Yangtao

2014-01-01

Al–5Ti–C master alloy was prepared and used to modify hypereutectic Al–20%Si alloy. The microstructure evolution and mechanical properties of hypereutectic Al–20%Si alloy with Al–5Ti–C master alloy additions (0, 0.4, 0.6, 1.0, 1.6 and 2.0 wt%) were investigated. The results show that, Al–5Ti–C master alloy (0.6 wt%, 10 min) can significantly refine both eutectic and primary Si of hypereutectic Al–20%Si alloy. The morphology of the primary Si crystals was significantly refined from a coarse polygonal and star-like shape to a fine polyhedral shape and the grain size of the primary Si was refined from roughly 90–120 μm to 20–50 μm. The eutectic Si phases were modified from a coarse platelet-like/needle-like structure to a fine fibrous structure with discrete particles. The Al–5Ti–C master alloy (0.6 wt%, 30 min) still has a good refinement effect. The ultimate tensile strength (UTS), elongation (El) and Brinell hardness (HB) of Al–20%Si alloy modified by the Al–5Ti–C master alloy (0.6 wt%, 10 min) increased by roughly 65%, 70% and 51%, respectively, due to decreasing the size and changing the morphology on the primary and eutectic Si crystals. The change in mechanical properties corresponds to evolution of the microstructure. PMID:28788509

Can high resolution 3D topographic surveys provide reliable grain size estimates in gravel bed rivers?

NASA Astrophysics Data System (ADS)

Pearson, E.; Smith, M. W.; Klaar, M. J.; Brown, L. E.

2017-09-01

High resolution topographic surveys such as those provided by Structure-from-Motion (SfM) contain a wealth of information that is not always exploited in the generation of Digital Elevation Models (DEMs). In particular, several authors have related sub-metre scale topographic variability (or 'surface roughness') to sediment grain size by deriving empirical relationships between the two. In fluvial applications, such relationships permit rapid analysis of the spatial distribution of grain size over entire river reaches, providing improved data to drive three-dimensional hydraulic models, allowing rapid geomorphic monitoring of sub-reach river restoration projects, and enabling more robust characterisation of riverbed habitats. However, comparison of previously published roughness-grain-size relationships shows substantial variability between field sites. Using a combination of over 300 laboratory and field-based SfM surveys, we demonstrate the influence of inherent survey error, irregularity of natural gravels, particle shape, grain packing structure, sorting, and form roughness on roughness-grain-size relationships. Roughness analysis from SfM datasets can accurately predict the diameter of smooth hemispheres, though natural, irregular gravels result in a higher roughness value for a given diameter and different grain shapes yield different relationships. A suite of empirical relationships is presented as a decision tree which improves predictions of grain size. By accounting for differences in patch facies, large improvements in D50 prediction are possible. SfM is capable of providing accurate grain size estimates, although further refinement is needed for poorly sorted gravel patches, for which c-axis percentiles are better predicted than b-axis percentiles.

Ultrafine-grained commercially pure titanium and microstructure response to hydroxyapatite coating methods

NASA Astrophysics Data System (ADS)

Calvert, Kayla L.

Commercially pure titanium (cp-Ti) is an ideal biomaterial as it does not evoke an inflammatory foreign body response in the body. However, the low strength of cp-Ti prevents the use in most orthopaedic load bearing applications. Therefore, many metal orthopaedic implants are commonly made of higher strength metal alloys that are less biocompatible. Nanostructured materials exhibit superior mechanical properties compared to their conventional grain sized counterparts. Severe plastic deformation (SPD) of metals has been shown to produce nanostructured materials. SPD by machining is a single-step deformation route that refines the grain microstructure, to develop an ultrafine grained (UFG) microstructure. UFG cp-Ti strips were developed with induced shear strains of up to 4.0 using a machining-based process. Both Vickers microhardness evaluation and microstructural analysis were used to characterize the as-received (annealed) and machined states. For induced shear strains between 1.9 and 4.0 in grade 2 cp-Ti the hardness was increased from 188 +/- 7 kg/mm2 in the as-received state to between 244 +/- 6 and 264 +/- 12 kg/mm 2 in the as-machined state, corresponding to an increase in hardness between 31 and 41%. The microstructural analysis revealed a grain size reduction from 34 +/- 11 mum in the as-received state to ˜ 100 nm for machined grade 2-Ti. A complete annealing study suggested that recovery/recrystallization occurs between 300 and 400°C, with a significant hardness drop between 400 and 600°C, while grain growth is continuous, starting at the lowest annealing temperature of 300°C. Hydroxyapatite (HA) is commonly applied to orthopaedic devices to promote bone growth. Machined Ti strips were coated with HA using conventional plasma spray as well as two alternative low-temperature application routes (sol-gel with calcination and anodization with hydrothermal treatment) to evaluate the thermal influence on the UFG-Ti substrate. Plasma spray produced a thick

US refining margin trend: austerity continues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Should crude oil prices hold near current levels in 1988, US refining margins might improve little, if at all. If crude oil prices rise, margins could blush pink or worse. If they drop, US refiners would still probably not see much margin improvement. In fact, if crude prices fall, they could set off another free fall in products markets and threaten refiner survival. Volatility in refined products markets and low product demand growth are the underlying reasons for caution or pessimism as the new year approaches. Recent directional patterns in refining margins are scrutinized in this issue. This issue alsomore » contains the following: (1) the ED refining netback data for the US Gulf and West Coasts, Rotterdam, and Singapore for late November, 1987; and (2) the ED fuel price/tax series for countries of the Eastern Hemisphere, November, 1987 edition. 4 figures, 6 tables.« less

Aspects of Western Refining, Inc.'s Proposed Acquisition of Giant Industries, Inc.

EIA Publications

2006-01-01

Presentation of company-level, non-proprietary data and relevant aggregate data for U.S. refinery capacity and gasoline marketing of Western Refining and Giant Industries to inform discussions of Western Refining Inc.'s proposed acquisition of Giant Industries Inc. for a total of $1.5 billion, which was announced August 28, 2006.

Next Generation Snow Cover Mapping: Can Future Hyperspectral Satellite Spectrometer Systems Improve Subpixel Snow-covered Area and Grain Size in the Sierra Nevada?

NASA Astrophysics Data System (ADS)

Hill, R.; Calvin, W. M.; Harpold, A.

2017-12-01

Mountain snow storage is the dominant source of water for humans and ecosystems in western North America. Consequently, the spatial distribution of snow-covered area is fundamental to both hydrological, ecological, and climate models. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were collected along the entire Sierra Nevada mountain range extending from north of Lake Tahoe to south of Mt. Whitney during the 2015 and 2016 snow-covered season. The AVIRIS dataset used in this experiment consists of 224 contiguous spectral channels with wavelengths ranging 400-2500 nanometers at a 15-meter spatial pixel size. Data from the Sierras were acquired on four days: 2/24/15 during a very low snow year, 3/24/16 near maximum snow accumulation, and 5/12/16 and 5/18/16 during snow ablation and snow loss. Building on previous retrieval of subpixel snow-covered area algorithms that take into account varying grain size we present a model that analyzes multiple endmembers of varying snow grain size, vegetation, rock, and soil in segmented regions along the Sierra Nevada to determine snow-cover spatial extent, snow sub-pixel fraction, and approximate grain size. In addition, varying simulated models of the data will compare and contrast the retrieval of current snow products such as MODIS Snow-Covered Area and Grain Size (MODSCAG) and the Airborne Space Observatory (ASO). Specifically, does lower spatial resolution (MODIS), broader resolution bandwidth (MODIS), and limited spectral resolution (ASO) affect snow-cover area and grain size approximations? The implications of our findings will help refine snow mapping products for planned hyperspectral satellite spectrometer systems such as EnMAP (slated to launch in 2019), HISUI (planned for inclusion on the International Space Station in 2018), and HyspIRI (currently under consideration).

Microstructure and Mechanical Properties of Ultrafine-Grained Al-6061 Prepared Using Intermittent Ultrasonic-Assisted Equal-Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Lu, Jianxun; Wu, Xiaoyu; Wu, Zhaozhi; Liu, Zhiyuan; Guo, Dengji; Lou, Yan; Ruan, Shuangchen

2017-10-01

Equal-channel angular pressing (ECAP) is an efficient technique to achieve grain refinement in a wide range of materials. However, the extrusion process requires an excessive extrusion force, the microstructure of ECAPed specimens scatters heterogeneously because of considerable fragmentation of the structure and strain heterogeneity, and the resultant ultrafine grains exhibit poor thermal stability. The intermittent ultrasonic-assisted ECAP (IU-ECAP) approach was proposed to address these issues. In this work, ECAP and IU-ECAP were applied to produce ultrafine-grained Al-6061 alloys, and the differences in their mechanical properties, microstructural characteristics, and thermal stability were investigated. Mechanical testing demonstrated that the necessary extrusion force for IU-ECAP was significantly reduced; even more, the microhardness and ultimate tensile strength were strengthened. In addition, the IU-ECAPed Al alloy exhibited a smaller grain size with a more homogeneous microstructure. X-ray diffraction analysis indicated that the intensities of the textures were weakened using IU-ECAP, and a more homogeneous microstructure and larger dislocation densities were obtained. Investigation of the thermal stability revealed that the ultrafine-grained materials produced using IU-ECAP recrystallized at higher temperature or after longer time; the materials thus exhibited improved thermal stability.

Effect of processing sorghum grain on dairy calf performance.

PubMed

Abdelgadir, I E; Morrill, J L

1995-09-01

Two trials evaluated the effect of sorghum grain processing on dairy calf performance. In trial 1, Holstein calves (n = 76; .5 to 8 wk of age) were fed one of three calf starters that contained either raw, roasted (exit temperature of 135 degrees C), or conglomerated sorghum grain. The conglomeration process consisted of grinding the grain, adding water, pelleting the mixture, and then roasting it. Raw and roasted sorghum grains were ground through a 3.2-mm screen and then included in complete pelleted starters; conglomerated sorghum grain pellets were mixed with the other pelleted ingredients of the starter. Processing did not enhance calf performance or affect selected ruminal and blood metabolites. In trial 2, roasted and conglomerated sorghum grains were ground through a 3.2-mm screen, and each was included in a pelleted starter fed for ad libitum intake to Holstein calves (n = 48) from .5 to 8 wk of age. Calf performance was not affected by method of grain processing, and ruminal and blood metabolites were similar; however, 22% of calves on the conglomerated sorghum grain starter bloated during the postweaning period, which probably resulted in reduced feed intake from wk 6 to 8. Measures to prevent bloat may be necessary to realize a potential benefit of conglomerating sorghum grain for calves.

eBits: Compact stream of mesh refinements for remote visualization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sati, Mukul; Lindstrom, Peter; Rossignac, Jarek

2016-05-12

Here, we focus on applications where a remote client needs to visualize or process a complex, manifold triangle mesh, M, but only in a relatively small, user controlled, Region of Interest (RoI) at a time. The client first downloads a coarse base mesh, pre-computed on the server via a series of simplification passes on M, one per Level of Detail (LoD), each pass identifying an independent set of triangles, collapsing them, and, for each collapse, storing, in a Vertex Expansion Record (VER), the information needed to reverse the collapse. On each client initiated RoI modification request, the server pushes tomore » the client a selected subset of these VERs, which, when decoded and applied to refine the mesh locally, ensure that the portion in the RoI is always at full resolution. The eBits approach proposed here offers state of the art compression ratios (using less than 2.5 bits per new full resolution RoI triangle when the RoI has more than 2000 vertices to transmit the connectivity for the selective refinements) and fine-grain control (allowing the user to adjust the RoI by small increments). The effectiveness of eBits results from several novel ideas and novel variations of previous solutions. We represent the VERs using persistent labels so that they can be applied in different orders within a given LoD. The server maintains a shadow copy of the client’s mesh. To avoid sending IDs identifying which vertices should be expanded, we either transmit, for each new vertex, a compact encoding of its death tag ​–the LoD at which it will be expanded if it lies in the RoI–or transmit vertex masks for the RoI and its neighboring vertices. We also propose a three-step simplification that reduces the overall transmission cost by increasing both the simplification effectiveness and the regularity of the valences in the resulting meshes.« less

eBits: Compact stream of mesh refinements for remote visualization

DOE PAGES

Sati, Mukul; Lindstrom, Peter; Rossignac, Jarek

2016-05-12

Here, we focus on applications where a remote client needs to visualize or process a complex, manifold triangle mesh, M, but only in a relatively small, user controlled, Region of Interest (RoI) at a time. The client first downloads a coarse base mesh, pre-computed on the server via a series of simplification passes on M, one per Level of Detail (LoD), each pass identifying an independent set of triangles, collapsing them, and, for each collapse, storing, in a Vertex Expansion Record (VER), the information needed to reverse the collapse. On each client initiated RoI modification request, the server pushes tomore » the client a selected subset of these VERs, which, when decoded and applied to refine the mesh locally, ensure that the portion in the RoI is always at full resolution. The eBits approach proposed here offers state of the art compression ratios (using less than 2.5 bits per new full resolution RoI triangle when the RoI has more than 2000 vertices to transmit the connectivity for the selective refinements) and fine-grain control (allowing the user to adjust the RoI by small increments). The effectiveness of eBits results from several novel ideas and novel variations of previous solutions. We represent the VERs using persistent labels so that they can be applied in different orders within a given LoD. The server maintains a shadow copy of the client’s mesh. To avoid sending IDs identifying which vertices should be expanded, we either transmit, for each new vertex, a compact encoding of its death tag–the LoD at which it will be expanded if it lies in the Rol–or transmit vertex masks for the RoI and its neighboring vertices. We also propose a three-step simplification that reduces the overall transmission cost by increasing both the simplification effectiveness and the regularity of the valences in the resulting meshes.« less

Effect of Various SPD Techniques on Structure and Superplastic Deformation of Two Phase MgLiAl Alloy

NASA Astrophysics Data System (ADS)

Dutkiewicz, Jan; Bobrowski, Piotr; Rusz, Stanislav; Hilser, Ondrej; Tański, Tomasz A.; Borek, Wojciech; Łagoda, Marek; Ostachowski, Paweł; Pałka, Paweł; Boczkal, Grzegorz; Kuc, Dariusz; Mikuszewski, Tomasz

2018-03-01

MgLiAl alloy containing 9 wt% Li and 1.5% Al composed of hexagonal α and bcc β 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 ɛ = 5 using MAXStrain Gleeble equipment, both performed at temperature interval 160-200 °C and, as third SPD method, KOBO type extrusion at RT. The TCAP pass resulted in grain refinement of α phase from 30 μm down to about 2 μm and that of β phase from 12 to 5 μm. Maxstrain cycling 10 × up to ɛ = 5 led to much finer grain size of 300 nm. KOBO method performed at RT caused average grain size refinement of α and β phases down to about 1 μm. 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 β region than in the α phase. Crystallographic relationship (001) α|| (110) β 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 °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 × 10-3 s-1. Deformation by MAXStrain cycling caused much more effective grain refinement with fine microtwins in α 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 °C and deformation rate in the

Effects of Wheat and Oat-Based Whole Grain Foods on Serum Lipoprotein Size and Distribution in Overweight Middle Aged People: A Randomised Controlled Trial

PubMed Central

Tighe, Paula; Duthie, Garry; Brittenden, Julie; Vaughan, Nicholas; Mutch, William; Simpson, William G.; Duthie, Susan; Horgan, Graham W.; Thies, Frank

2013-01-01

Introduction Epidemiological studies suggest three daily servings of whole-grain foods (WGF) might lower cardiovascular disease risk, at least partly by lowering serum lipid levels. We have assessed the effects of consuming three daily portions of wholegrain food (provided as wheat or a mixture of wheat and oats) on lipoprotein subclass size and concentration in a dietary randomised controlled trial involving middle aged healthy individuals. Methods After a 4-week run-in period on a refined diet, volunteers were randomly allocated to a control (refined diet), wheat, or wheat + oats group for 12 weeks. Our servings were determined in order to significantly increase the intakes of non starch polysaccharides to the UK Dietary Reference Value of 18 g per day in the whole grain groups (18.5 g and 16.8 g per day in the wheat and wheat + oats groups respectively in comparison with 11.3 g per day in the control group). Outcome measures were serum lipoprotein subclasses' size and concentration. Habitual dietary intake was assessed prior and during the intervention. Of the 233 volunteers recruited, 24 withdrew and 3 were excluded. Results At baseline, significant associations were found between lipoprotein size and subclasses' concentrations and some markers of cardiovascular risk such as insulin resistance, blood pressure and serum Inter cellular adhesion molecule 1 concentration. Furthermore, alcohol and vitamin C intake were positively associated with an anti-atherogenic lipoprotein profile, with regards to lipoprotein size and subclasses' distribution. However, none of the interventions with whole grain affected lipoprotein size and profile. Conclusion Our results indicate that three portions of wholegrain foods, irrelevant of the type (wheat or oat-based) do not reduce cardiovascular risk by beneficially altering the size and distribution of lipoprotein subclasses. Trial Registration www.Controlled-Trials.com ISRCTN 27657880. PMID:23940575

Grain Foods Are Contributors of Nutrient Density for American Adults and Help Close Nutrient Recommendation Gaps: Data from the National Health and Nutrition Examination Survey, 2009-2012.

PubMed

Papanikolaou, Yanni; Fulgoni, Victor L

2017-08-14

The 2015-2020 Dietary Guidelines for Americans (2015-2020 DGA) maintains recommendations for increased consumption of whole grains while limiting intake of enriched/refined grains. A variety of enriched grains are sources of several shortfall nutrients identified by 2015-2020 DGA, including dietary fiber, folate, iron, and magnesium. The purpose of this study was to determine food sources of energy and nutrients for free-living U.S. adults using data from the National Health and Nutrition Examination Survey, 2009-2012. Analyses of grain food sources were conducted using a single 24-h recall collected in adults ≥19 years of age ( n = 10,697). Sources of nutrients contained in all grain foods were determined using United States Department of Agriculture nutrient composition databases and the food grouping scheme for grains (excluding mixed dishes). Mean energy and nutrient intakes from the total diet and from various grain food groups were adjusted for the sample design using appropriate weights. All grains provided 285 ± 5 kcal/day or 14 ± 0.2% kcal/day in the total diet in adult ≥19 years of age. In the total daily diet, the grain category provided 7.2 ± 0.2% (4.9 ± 0.1 g/day) total fat, 5.4 ± 0.2% (1.1 ± 0.03 g/day) saturated fat, 14.6 ± 0.3% (486 ± 9 mg/day) sodium, 7.9 ± 0.2% (7.6 ± 0.2 g/day) total sugar, 22.8 ± 0.4% (3.9 ± 0.1 g/day) dietary fiber, 13.2 ± 0.3% (122 ± 3 mg/day) calcium, 33.6 ± 0.5% (219 ± 4 mcg dietary folate equivalents (DFE)/day) folate, 29.7 ± 0.4% (5.3 ± 0.1 mg/day) iron, and 13.9 ± 0.3% (43.7 ± 1.1 mg/day) magnesium. Individual grain category analyses showed that breads, rolls and tortillas and ready-to-eat cereals provided minimal kcal/day in the total diet in men and women ≥19 years of age. Similarly, breads, rolls and tortillas, and ready-to-eat cereals supplied meaningful contributions of shortfall nutrients, including dietary fiber, folate and iron, while concurrently providing minimal amounts of nutrients to

Impact fracture experiments simulating interstellar grain-grain collisions

NASA Technical Reports Server (NTRS)

Freund, Friedemann; Chang, Sherwood; Dickinson, J. Thomas

1990-01-01

Oxide and silicate grains condensing during the early phases of the formation of the solar system or in the outflow of stars are exposed to high partial pressures of the low-z elements H, C, N and O and their simple gaseous compounds. Though refractory minerals are nominally anhydrous and non-carbonate, if they crystallize in the presence of H2O, N2 and CO or CO2 gases, they dissolve traces of the gaseous components. The question arises: How does the presence of dissolved gases or gas components manifest itself when grain-grain collisions occur. What are the gases emitted when grains are shattered during a collision event. Researchers report on fracture experiments in ultrahigh vacuum (UHV, approximately less than 10 to the -8th power mbar) designed to measure (by means of a quadrupole mass spectrometer, QMS, with microns to ms time resolution) the emission of gases and vapors during and after impact (up to 1.5 sec). Two terrestrial materials were chosen which represent structural and compositional extremes: olivine (San Carlos, AZ), a densely packed Mg-Fe(2+) silicate from the upper mantle, available as 6 to 12 mm single crystals, and obsidian (Oregon), a structurally open, alkaline-SiO2-rich volcanic glass. In the olivine crystals OH- groups have been identified spectroscopically, as well as H2 molecules. Obsidian is a water-rich glass containing OH- besides H2O molecules. Olivine from the mantle often contains CO2, either as CO2-rich fluid in fluid inclusions or structurally dissolved or both. By analogy to synthetic glasses CO2 in the obsidian may be present in form of CO2 molecules in voids of molecular dimensions, or as carbonate anions, CO3(2-). No organic molecules have been detected spectroscopically in either material. Results indicate that refractory oxide/silicates which contain dissolved traces of the H2O and CO/CO2 components but no spectroscopically detectable traces of organics may release complex H-C-O (possibly H-C-N-O) molecules upon fracture

40 CFR 80.551 - How does a refiner obtain approval as a small refiner under this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... application for small refiner status. EPA may accept such alternate data at its discretion. (4) For motor... a small refiner under this subpart? 80.551 Section 80.551 Protection of Environment ENVIRONMENTAL... Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Small Refiner Hardship...

40 CFR 80.551 - How does a refiner obtain approval as a small refiner under this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... application for small refiner status. EPA may accept such alternate data at its discretion. (4) For motor... a small refiner under this subpart? 80.551 Section 80.551 Protection of Environment ENVIRONMENTAL... Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Small Refiner Hardship...

40 CFR 80.551 - How does a refiner obtain approval as a small refiner under this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... application for small refiner status. EPA may accept such alternate data at its discretion. (4) For motor... a small refiner under this subpart? 80.551 Section 80.551 Protection of Environment ENVIRONMENTAL... Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Small Refiner Hardship...

40 CFR 80.551 - How does a refiner obtain approval as a small refiner under this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... application for small refiner status. EPA may accept such alternate data at its discretion. (4) For motor... a small refiner under this subpart? 80.551 Section 80.551 Protection of Environment ENVIRONMENTAL... Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Small Refiner Hardship...

40 CFR 180.658 - Penthiopyrad; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., subgroup 5A 5.0 Brassica, leafy greens, subgroup 5B 50 Buckwheat, grain 0.15 Canola 1.5 Corn, field, forage 40 Corn, field, grain 0.01 Corn, field, refined oil 0.05 Corn, field, stover 15 Corn, pop, grain 0.01 Corn, sweet, kernel plus cob with husks removed 0.01 Cotton, seed 1.5 Cotton, gin byproducts 15 Fruit...

40 CFR 180.658 - Penthiopyrad; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., subgroup 5A 5.0 Brassica, leafy greens, subgroup 5B 50 Buckwheat, grain 0.15 Canola 1.5 Corn, field, forage 40 Corn, field, grain 0.01 Corn, field, refined oil 0.05 Corn, field, stover 15 Corn, pop, grain 0.01 Corn, sweet, kernel plus cob with husks removed 0.01 Cotton, seed 1.5 Cotton, gin byproducts 15 Fruit...

40 CFR 180.658 - Penthiopyrad; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., subgroup 5A 5.0 Brassica, leafy greens, subgroup 5B 50 Buckwheat, grain 0.15 Canola 1.5 Corn, field, forage 40 Corn, field, grain 0.01 Corn, field, refined oil 0.05 Corn, field, stover 15 Corn, pop, grain 0.01 Corn, sweet, kernel plus cob with husks removed 0.01 Cotton, seed 1.5 Cotton, gin byproducts 15 Fruit...

Unstable plastic deformation of ultrafine-grained copper at 0.5 K

NASA Astrophysics Data System (ADS)

Isaev, N. V.; Grigorova, T. V.; Shumilin, S. E.; Polishchuk, S. S.; Davydenko, O. A.

2017-12-01

We investigate the relation between the strain-hardening rate and flow instability of polycrystalline Cu-OF deformed by tension at a constant rate in a liquid 3He atmosphere. The microstructure of the ultrafine-grained crystal, obtained by the equal-channel angular hydro-extrusion method, was varied by annealing at recovery and recrystallization temperatures and was monitored by x-ray diffraction. It is shown that that the flow instability, manifesting itself as macroscopic stress serrations on the tension curve, appears at a threshold tension sufficient for activation of a dynamic recovery that leads to a decrease of the strain-hardening coefficient. We discuss the effect of grain size and the initial dislocation density on the evolution of the dislocation structure that determines the scale and the statistical properties of the flow instability in the investigated crystals at low temperature.

Firing of pulverized solvent refined coal

DOEpatents

Derbidge, T. Craig; Mulholland, James A.; Foster, Edward P.

1986-01-01

An air-purged burner for the firing of pulverized solvent refined coal is constructed and operated such that the solvent refined coal can be fired without the coking thereof on the burner components. The air-purged burner is designed for the firing of pulverized solvent refined coal in a tangentially fired boiler.

40 CFR 80.1340 - How does a refiner obtain approval as a small refiner?

Code of Federal Regulations, 2012 CFR

2012-07-01

... EPA with appropriate data to correct the record when the company submits its application for small... a small refiner? 80.1340 Section 80.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Small Refiner...

Cross-Grain Knife Planing Improves Surface Quality and Utilization of Aspen

Treesearch

Harold A. Stewart

1971-01-01

Aspen at 6 percent moisture content was planed parallel to the grain and across the grain on a cabinet planer with a 25? rake angle, 1/16- and 1/32-inch depth of cut, and 20 knife marks per inch. Aspen was also cross-grain knife planed with a 45? rake angle, 1/32-, 1/16-, and 1/8-inch depths of cut, and 20, 10, 5, and 2.5 knife marks per inch. Cross-grain knife...

Animal model of grain worker's lung.

PubMed Central

Stepner, N; Broder, I; Baumal, R

1986-01-01

We examined the light microscopic changes in the lungs of rabbits exposed to grain dust for variable periods of time, to determine whether an animal model of grain worker's lung could be developed. Experimental animals were exposed to grain dust at a concentration of 20 mg/m3 for 7 hr/day, 5 days/week, for up to 6 months. The lungs of these rabbits demonstrated a granulomatous interstitial pneumonitis associated with exudation of mononuclear cells into the alveoli and conducting airways. These changes appeared within 5 days of the onset of exposure and reached a peak at 3 weeks but were sustained through the longest exposure interval. No abnormalities were observed in the lungs of control rabbits. These results show three points of consistency with those obtained in epidemiologic studies of grain elevator workers. First, the rapid appearance of the experimental changes suggests that the mechanism of tissue injury may not be immunologic. Second, the occurrence of the histopathologic alterations in the interstitium, alveoli, and airways corresponds with the combined restrictive and obstructive ventilatory defect described in the human epidemiologic studies. Third, the absence of lung fibrosis in rabbits exposed to dust for 6 months suggests that the pneumonitis is reversible. Thus this experimental model shows promise of helping to clarify the nature and mechanism of the adverse pulmonary effects of grain dust. Images FIGURE 1. FIGURE 2. PMID:3709485

Structure, electronic properties, and oxygen incorporation/diffusion characteristics of the Σ 5 TiN(310)[001] tilt grain boundary

NASA Astrophysics Data System (ADS)

McKenna, Keith P.

2018-02-01

First principles calculations are employed to investigate the structure, electronic properties, and oxygen incorporation/diffusion characteristics of the Σ 5 TiN(310) tilt grain boundary with relevance to applications of polycrystalline TiN in microelectronics and protective coatings. We show that the grain boundary does not significantly modify electronic states near the Fermi energy but does induce an upward shift of up to 0.6 eV in a number of deeper occupied bands. We also show that oxygen is preferentially incorporated into the TiN grain boundary (GB) but must overcome relatively high activation energies for further diffusion. These predictions are consistent with the "stuffed barrier model" proposed to explain the good barrier characteristics of TiN. We also show that while the oxidizing power of TiN GBs is not sufficient to reduce HfO2 (a prototypical gate dielectric material), they can act as a scavenger for interstitial oxygen. Altogether, these results provide the much needed atomistic insights into the properties of a model GB in TiN and suggest a number of directions for future investigation.

Effective grain pinning revealed by nanoscale electron tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Y. Q.; Tang, W.; Dennis, K. W.

2011-03-21

The grain pinning behavior of TiC particles in a rapidly solidified MRE-Fe-B (MRE = Nd + Y + Dy) nanocrystalline hard magnet was studied using electron tomography (ET). The 3D reconstruction overcomes the inherent 2D nature of conventional transmission electronmicroscopy (TEM) to reveal how this grain boundary phase controls the nanoscale structure in the rapidly solidified alloy. The 3D reconstruction was performed on the optimally annealed alloy (750 C/15 min) with hard magnetic properties of M{sub r} = 8.1 kGs, H{sub c} = 6.2 kOe, (BH){sub max} = 11.2 MGOe measured at 300 k. The sampled volume, 425 x 425more » x 92.5 nm{sup 3}, contains more than 20 grains of the RE2-14-1 phase and more than 70 TiC nanoparticles. The TiC grains shapes depend on their sizes and locations along the grain boundary. Most of the TiC particles are oval or short rod like shapes and range from 5 nm to 10 nm. TiC particles less than 10 nm formed between adjacent 2-14-1 grains, while the largest ones formed at triple junctions. There are -1.7 x 10{sup 8} TiC particles within a 1 mm{sup 3} volume in the alloy. This accounts for the strong grain boundary pinning effect, which limits grain growth during annealing.« less

A Refined Cauchy-Schwarz Inequality

ERIC Educational Resources Information Center

Mercer, Peter R.

2007-01-01

The author presents a refinement of the Cauchy-Schwarz inequality. He shows his computations in which refinements of the triangle inequality and its reverse inequality are obtained for nonzero x and y in a normed linear space.

Chemical and microbiological characterisation of kefir grains.

PubMed

Garrote, G L; Abraham, A G; De Antoni, G L

2001-11-01

Chemical and microbiological composition of four Argentinean kefir grains from different sources as well as characteristics of the corresponding fermented milk were studied. Kefir grains CIDCA AGK1, AGK2 and AGK4 did not show significant differences in their chemical and microbiological composition. In contrast, protein and yeast content of AGK3 was higher than in the other grains. Although grain microflora comprised lactobacilli, lactococcus, acetic acid bacteria and yeast, we found an important difference regarding species. Lactococcus lactis subsp. lactis, Lactobacillus kefir, Lactobacillus plantarum, Acetobacter and Saccharomyces were present in all types of kefir grain. While Leuconostoc mesenteroides was only isolated from grains CIDCA AGK1 and Lactococcus lactis subsp. lactis biovar diacetylactis, Lactobacillus parakefir and Kluyveromyces marxianus were only isolated from CIDCA AGK2 grains. All grains produced acid products with pH between 3.5 and 4.0. The apparent viscosity of AGK1 fermented milk was greater than the product obtained with AGK4. All fermented milks had inhibitory power towards Escherichia coli but AGK1 and AGK2 supernatants were able to halt the bacterial growth for at least 25 h. Grain weight increment in AGK1, AGK2 and AGK3 during growth in milk did not show significant differences. Despite their fermenting activity, AGK4 grains did not increase their weight.

Prevalence of IgE antibodies to grain and grain dust in grain elevator workers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, D.M.; Romeo, P.A.; Olenchock, S.A.

1986-04-01

IgE-mediated allergic reactions have been postulated to contribute to respiratory reactions seen in workers exposed to grain dusts. In an attempt better to define the prevalence of IgE antibodies in workers exposed to grain dusts, we performed the radioallergosorbent test (RAST) on worker sera using both commercial allergens prepared from grain and worksite allergens prepared from grain dust samples collected at the worksite. We found that the two types of reagents identified different populations with respect to the specificity of IgE antibodies present. The RAST assay performed using worksite allergens correlated well with skin test procedures. These results may allowmore » us to gain better understanding of allergy associated with grain dust exposure, and document the utility of the RAST assay in assessment of occupational allergies.« less

Prevalence of IgE antibodies to grain and grain dust in grain elevator workers.

PubMed Central

Lewis, D M; Romeo, P A; Olenchock, S A

1986-01-01

IgE-mediated allergic reactions have been postulated to contribute to respiratory reactions seen in workers exposed to grain dusts. In an attempt better to define the prevalence of IgE antibodies in workers exposed to grain dusts, we performed the radioallergosorbent test (RAST) on worker sera using both commercial allergens prepared from grain and worksite allergens prepared from grain dust samples collected at the worksite. We found that the two types of reagents identified different populations with respect to the specificity of IgE antibodies present. The RAST assay performed using worksite allergens correlated well with skin test procedures. These results may allow us to gain better understanding of allergy associated with grain dust exposure, and document the utility of the RAST assay in assessment of occupational allergies. PMID:3709478

Grain Foods Are Contributors of Nutrient Density for American Adults and Help Close Nutrient Recommendation Gaps: Data from the National Health and Nutrition Examination Survey, 2009–2012

PubMed Central

Papanikolaou, Yanni; Fulgoni, Victor L.

2017-01-01

The 2015–2020 Dietary Guidelines for Americans (2015-2020 DGA) maintains recommendations for increased consumption of whole grains while limiting intake of enriched/refined grains. A variety of enriched grains are sources of several shortfall nutrients identified by 2015-2020 DGA, including dietary fiber, folate, iron, and magnesium. The purpose of this study was to determine food sources of energy and nutrients for free-living U.S. adults using data from the National Health and Nutrition Examination Survey, 2009–2012. Analyses of grain food sources were conducted using a single 24-h recall collected in adults ≥19 years of age (n = 10,697). Sources of nutrients contained in all grain foods were determined using United States Department of Agriculture nutrient composition databases and the food grouping scheme for grains (excluding mixed dishes). Mean energy and nutrient intakes from the total diet and from various grain food groups were adjusted for the sample design using appropriate weights. All grains provided 285 ± 5 kcal/day or 14 ± 0.2% kcal/day in the total diet in adult ≥19 years of age. In the total daily diet, the grain category provided 7.2 ± 0.2% (4.9 ± 0.1 g/day) total fat, 5.4 ± 0.2% (1.1 ± 0.03 g/day) saturated fat, 14.6 ± 0.3% (486 ± 9 mg/day) sodium, 7.9 ± 0.2% (7.6 ± 0.2 g/day) total sugar, 22.8 ± 0.4% (3.9 ± 0.1 g/day) dietary fiber, 13.2 ± 0.3% (122 ± 3 mg/day) calcium, 33.6 ± 0.5% (219 ± 4 mcg dietary folate equivalents (DFE)/day) folate, 29.7 ± 0.4% (5.3 ± 0.1 mg/day) iron, and 13.9 ± 0.3% (43.7 ± 1.1 mg/day) magnesium. Individual grain category analyses showed that breads, rolls and tortillas and ready-to-eat cereals provided minimal kcal/day in the total diet in men and women ≥19 years of age. Similarly, breads, rolls and tortillas, and ready-to-eat cereals supplied meaningful contributions of shortfall nutrients, including dietary fiber, folate and iron, while concurrently providing minimal amounts of nutrients

Refined geometric transition and qq-characters

NASA Astrophysics Data System (ADS)

Kimura, Taro; Mori, Hironori; Sugimoto, Yuji

2018-01-01

We show the refinement of the prescription for the geometric transition in the refined topological string theory and, as its application, discuss a possibility to describe qq-characters from the string theory point of view. Though the suggested way to operate the refined geometric transition has passed through several checks, it is additionally found in this paper that the presence of the preferred direction brings a nontrivial effect. We provide the modified formula involving this point. We then apply our prescription of the refined geometric transition to proposing the stringy description of doubly quantized Seiberg-Witten curves called qq-characters in certain cases.

US refining sector still a whipping-boy: what will it take

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1988-01-27

The fast moving US product markets are exerting a powerful pull on crude oil prices. This has meant unalleviated downward pressure on refining margins for most of the past year. Downstream of refining, product marketers want the lower rack and spot prices from refineries. Upstream, independent and major-integrated producers want the highest crude prices they can obtain, with the latter producers also wanting the highest product value realizations. Refiners, especially the major-integrated ones, are rooting for OPEC discipline louder than anybody else. This issue also contains the following: (1) weighted dollar values by product for total product barrel at variousmore » sites around the globe; (2) ED refining netback data for the US Gulf and West Coasts, Rotterdam, and Singapore for late January 1988; and (3) ED fuel price/tax series for both the Western and Eastern Hemispheres, Jan. 1988 edition. 5 figures, 18 tables.« less

40 CFR 80.551 - How does a refiner obtain approval as a small refiner under this subpart?

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Applications for motor vehicle diesel fuel small refiner status must be submitted to EPA by December 31, 2001. (ii) Applications for NRLM diesel fuel small refiner status must be submitted to EPA by December 31, 2004. (2)(i) In the case of a refiner who acquires or reactivates a refinery that was shutdown or non...

Refining of metallurgical-grade silicon

NASA Technical Reports Server (NTRS)

Dietl, J.

1986-01-01

A basic requirement of large scale solar cell fabrication is to provide low cost base material. Unconventional refining of metallurical grade silicon represents one of the most promising ways of silicon meltstock processing. The refining concept is based on an optimized combination of metallurgical treatments. Commercially available crude silicon, in this sequence, requires a first pyrometallurgical step by slagging, or, alternatively, solvent extraction by aluminum. After grinding and leaching, high purity qualtiy is gained as an advanced stage of refinement. To reach solar grade quality a final pyrometallurgical step is needed: liquid-gas extraction.

40 CFR 80.1340 - How does a refiner obtain approval as a small refiner?

Code of Federal Regulations, 2014 CFR

2014-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Small Refiner... for small refiner status must be sent to: Attn: MSAT2 Benzene, Mail Stop 6406J, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. For commercial delivery: MSAT2 Benzene...

40 CFR 80.1340 - How does a refiner obtain approval as a small refiner?

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Small Refiner... for small refiner status must be sent to: Attn: MSAT2 Benzene, Mail Stop 6406J, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. For commercial delivery: MSAT2 Benzene...

40 CFR 80.1340 - How does a refiner obtain approval as a small refiner?

Code of Federal Regulations, 2013 CFR

2013-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Small Refiner... for small refiner status must be sent to: Attn: MSAT2 Benzene, Mail Stop 6406J, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. For commercial delivery: MSAT2 Benzene...

40 CFR 80.1344 - What provisions are available to a non-small refiner that acquires one or more of a small refiner...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-small refiner that acquires one or more of a small refiner's refineries? 80.1344 Section 80.1344... available to a non-small refiner that acquires one or more of a small refiner's refineries? (a) In the case of a refiner that is not an approved small refiner under § 80.1340 and that acquires a refinery from...

40 CFR 80.555 - What provisions are available to a large refiner that acquires a small refiner or one or more of...

Code of Federal Regulations, 2010 CFR

2010-07-01

... large refiner that acquires a small refiner or one or more of its refineries? 80.555 Section 80.555... that acquires a small refiner or one or more of its refineries? (a) In the case of a refiner without approved small refiner status who acquires a refinery from a refiner with approved status as a motor...

Grain Spectroscopy

NASA Technical Reports Server (NTRS)

Allamandola, L. J.

1992-01-01

Our fundamental knowledge of interstellar grain composition has grown substantially during the past two decades thanks to significant advances in two areas: astronomical infrared spectroscopy and laboratory astrophysics. The opening of the mid-infrared, the spectral range from 4000-400 cm(sup -1) (2.5-25 microns), to spectroscopic study has been critical to this progress because spectroscopy in this region reveals more about a materials molecular composition and structure than any other physical property. Infrared spectra which are diagnostic of interstellar grain composition fall into two categories: absorption spectra of the dense and diffuse interstellar media, and emission spectra from UV-Vis rich dusty regions. The former will be presented in some detail, with the latter only very briefly mentioned. This paper summarized what we have learned from these spectra and presents 'doorway' references into the literature. Detailed reviews of many aspects of interstellar dust are given.

Microstructural changes in Beta-silicon nitride grains upon crystallizing the grain-boundary glass

NASA Technical Reports Server (NTRS)

Lee, William E.; Hilmas, Gregory E.; Lange, F. F. (Editor)

1991-01-01

Crystallizing the grain boundary glass of a liquid phase sintered Si3N4 ceramic for 2 h or less at 1500 C led to formation of gamma Y2Si2O7. After 5 h at 1500 C, the gamma Y2Si2O7 had transformed to beta Y2Si2O7 with a concurrent dramatic increase in dislocation density within beta Si3N4 grains. Reasons for the increased dislocation density is discussed. Annealing for 20 h at 1500 C reduced dislocation densities to the levels found in as-sintered materials.

A Generic Force Field for Protein Coarse-Grained Molecular Dynamics Simulation

PubMed Central

Gu, Junfeng; Bai, Fang; Li, Honglin; Wang, Xicheng

2012-01-01

Coarse-grained (CG) force fields have become promising tools for studies of protein behavior, but the balance of speed and accuracy is still a challenge in the research of protein coarse graining methodology. In this work, 20 CG beads have been designed based on the structures of amino acid residues, with which an amino acid can be represented by one or two beads, and a CG solvent model with five water molecules was adopted to ensure the consistence with the protein CG beads. The internal interactions in protein were classified according to the types of the interacting CG beads, and adequate potential functions were chosen and systematically parameterized to fit the energy distributions. The proposed CG force field has been tested on eight proteins, and each protein was simulated for 1000 ns. Even without any extra structure knowledge of the simulated proteins, the Cα root mean square deviations (RMSDs) with respect to their experimental structures are close to those of relatively short time all atom molecular dynamics simulations. However, our coarse grained force field will require further refinement to improve agreement with and persistence of native-like structures. In addition, the root mean square fluctuations (RMSFs) relative to the average structures derived from the simulations show that the conformational fluctuations of the proteins can be sampled. PMID:23203075

Densification and Grain Growth in Polycrystalline Olivine Rocks Synthesized By Evacuated Hot-Pressing

NASA Astrophysics Data System (ADS)

Meyers, C. D.; Kohlstedt, D. L.; Zimmerman, M. E.

2017-12-01

Experiments on laboratory-synthesized olivine-rich rocks form the starting material for many investigations of physical processes in the Earth's upper mantle (e.g., creep behavior, ionic diffusion, and grain growth). Typically, a fit of a constitutive law to experimental data provides a description of the kinetics of a process needed to extrapolate across several orders of magnitude from laboratory to geological timescales. Although grain-size is a critical parameter in determining physical properties such as viscosity, broad disagreement persists amongst the results of various studies of grain growth kinetics in olivine-rich rocks. Small amounts of impurities or porosity dramatically affect the kinetics of grain growth. In this study, we developed an improved method for densifying olivine-rich rocks fabricated from powdered, gem-quality single crystals that involves evacuating the pore space, with the aim of refining measurements of the kinetics of mantle materials. In previous studies, olivine powders were sealed in a metal can and hydrostatically annealed at roughly 300 MPa and 1250 °C. These samples, which appear opaque and milky-green, typically retain a small amount of porosity. Consequently, when annealed at 1 atm, extensive pore growth occurs, inhibiting grain growth. In addition, Fourier-transform infrared and confocal Raman spectroscopy reveal absorption peaks characteristic of CO2 in the pores of conventionally hot-pressed material. To avoid trapping of adsorbed contaminants, we developed an evacuated hot-pressing method, wherein the pore space of powder compacts is vented to vacuum during heating and pressurization. This method produces a highly dense, green-tinted, transparent material. No CO2 absorptions peaks exist in evacuated hot-pressed material. When reheated to annealing temperatures at 1 atm, the evacuated hot-pressed material undergoes limited pore growth and dramatically enhanced grain-growth rates. High-strain deformation experiments on

Whole grain cereals for the primary or secondary prevention of cardiovascular disease.

PubMed

Kelly, Sarah Am; Hartley, Louise; Loveman, Emma; Colquitt, Jill L; Jones, Helen M; Al-Khudairy, Lena; Clar, Christine; Germanò, Roberta; Lunn, Hannah R; Frost, Gary; Rees, Karen

2017-08-24

There is evidence from observational studies that whole grains can have a beneficial effect on risk for cardiovascular disease (CVD). Earlier versions of this review found mainly short-term intervention studies. There are now longer-term randomised controlled trials (RCTs) available. This is an update and expansion of the original review conducted in 2007. The aim of this systematic review was to assess the effect of whole grain foods or diets on total mortality, cardiovascular events, and cardiovascular risk factors (blood lipids, blood pressure) in healthy people or people who have established cardiovascular disease or related risk factors, using all eligible RCTs. We searched CENTRAL (Issue 8, 2016) in the Cochrane Library, MEDLINE (1946 to 31 August 2016), Embase (1980 to week 35 2016), and CINAHL Plus (1937 to 31 August 2016) on 31 August 2016. We also searched ClinicalTrials.gov on 5 July 2017 and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) on 6 July 2017. We checked reference lists of relevant articles and applied no language restrictions. We selected RCTs assessing the effects of whole grain foods or diets containing whole grains compared to foods or diets with a similar composition, over a minimum of 12 weeks, on cardiovascular disease and related risk factors. Eligible for inclusion were healthy adults, those at increased risk of CVD, or those previously diagnosed with CVD. Two review authors independently selected studies. Data were extracted and quality-checked by one review author and checked by a second review author. A second review author checked the analyses. We assessed treatment effect using mean difference in a fixed-effect model and heterogeneity using the I 2 statistic and the Chi 2 test of heterogeneity. We assessed the overall quality of evidence using GRADE with GRADEpro software. We included nine RCTs randomising a total of 1414 participants (age range 24 to 70; mean age 45 to 59, where

3D Radiative Transfer Code for Polarized Scattered Light with Aligned Grains

NASA Astrophysics Data System (ADS)

Pelkonen, V. M.; Penttilä, A.; Juvela, M.; Muinonen, K.

2017-12-01

Polarized scattered light has been observed in cometary comae and in circumstellar disks. It carries information about the grains from which the light scattered. However, modelling polarized scattered light is a complicated problem. We are working on a 3D Monte Carlo radiative transfer code which incorporates hierarchical grid structure (octree) and the full Stokes vector for both the incoming radiation and the radiation scattered by dust grains. In octree grid format an upper level cell can be divided into 8 subcells by halving the cell in each of the three axis. Levels of further refinement of the grid may be added, until the desired resolution is reached. The radiation field is calculated with Monte Carlo methods. The path of the model ray is traced in the cloud: absorbed intensity is counted in each cell, and from time to time, the model ray is scattered towards a new direction as determined by the dust model. Due to the non-spherical grains and the polarization, the scattering problem will be the main issue for the code and most time consuming. The scattering parameters will be taken from the models for individual grains. We can introduce populations of different grain shapes into the dust model, and randomly select, based on their amounts, from which shape the model ray scatters. Similarly, we can include aligned and non-aligned subpopulations of these grains, based on the grain alignment calculations, to see which grains should be oriented with the magnetic field, or, in the absence of a magnetic field close to the comet nucleus, with another axis of alignment (e.g., the radiation direction). The 3D nature of the grid allows us to assign these values, as well as density, for each computational cell, to model phenomena like e.g., cometary jets. The code will record polarized scattered light towards one or more observer directions within a single simulation run. These results can then be compared with the observations of comets at different phase angles, or

Water-saving technologies affect the grain characteristics and recovery of fine-grain rice cultivars in semi-arid environment.

PubMed

Jabran, Khawar; Riaz, Muhammad; Hussain, Mubshar; Nasim, Wajid; Zaman, Umar; Fahad, Shah; Chauhan, Bhagirath Singh

2017-05-01

Growing rice with less water is direly needed due to declining water sources worldwide, but using methods that require less water inputs can have an impact on grain characteristics and recovery. A 2-year field study was conducted to evaluate the impact of conventionally sown flooded rice and low-water-input rice systems on the grain characteristics and recovery of fine rice. Three fine grain rice cultivars-Super Basmati, Basmati 2000, and Shaheen Basmati-were grown under conventional flooded transplanted rice (CFTR), alternate wetting and drying (AWD), and aerobic rice systems. Grain characteristics and rice recovery were significantly influenced by different water regimes (production systems). Poor milling, including the lowest percentage of brown (head) rice (65.3%) and polished (white) rice (64.2-66.9%) and the highest percentage of broken brown rice (10.2%), husk (24.5%-26.3%), polished broken rice (24.7%), and bran (11.0-12.5%), were recorded in the aerobic rice system sown with Shaheen Basmati. With a few exceptions, cultivars sown in CFTR were found to possess a higher percentage of brown (head) and polished (white) rice and they had incurred the least losses in the form of brown broken rice, husk, polished broken rice, and bran. In conclusion, better grain quality and recovery of rice can be attained by growing Super Basmati under the CFTR system. Growing Shaheen Basmati under low-water-input systems, the aerobic rice system in particular, resulted in poor grain characteristics tied with less rice recovery.

Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stráská, Jitka, E-mail: straska.jitka@gmail.com; Janeček, Miloš, E-mail: janecek@met.mff.cuni.cz; Čížek, Jakub, E-mail: jcizek@mbox.troja.mff.cuni.cz

Thermal stability of the ultra-fine grained (UFG) microstructure of magnesium AZ31 alloy was investigated. UFG microstructure was achieved by a combined two-step severe plastic deformation process: the extrusion (EX) and subsequent equal-channel angular pressing (ECAP). This combined process leads to refined microstructure and enhanced microhardness. Specimens with UFG microstructure were annealed isochronally at temperatures 150–500 °C for 1 h. The evolution of microstructure, mechanical properties and dislocation density was studied by electron backscatter diffraction (EBSD), microhardness measurements and positron annihilation spectroscopy (PAS). The coarsening of the fine-grained structure at higher temperatures was accompanied by a gradual decrease of the microhardnessmore » and decrease of dislocation density. Mechanism of grain growth was studied by general equation for grain growth and Arrhenius equation. Activation energies for grain growth were calculated to be 115, 33 and 164 kJ/mol in temperature ranges of 170–210 °C, 210–400 °C and 400–500 °C (443–483 K, 483–673 K and 673–773 K), respectively. - Highlights: • Microhardness of UFG AZ31 alloy decreases with increasing annealing temperature. • This fact has two reasons: dislocation annihilations and/or grain growth. • The activation energies for grain growth were calculated for all temperature ranges.« less

Exploiting structure similarity in refinement: automated NCS and target-structure restraints in BUSTER.

PubMed

Smart, Oliver S; Womack, Thomas O; Flensburg, Claus; Keller, Peter; Paciorek, Włodek; Sharff, Andrew; Vonrhein, Clemens; Bricogne, Gérard

2012-04-01

Maximum-likelihood X-ray macromolecular structure refinement in BUSTER has been extended with restraints facilitating the exploitation of structural similarity. The similarity can be between two or more chains within the structure being refined, thus favouring NCS, or to a distinct 'target' structure that remains fixed during refinement. The local structural similarity restraints (LSSR) approach considers all distances less than 5.5 Å between pairs of atoms in the chain to be restrained. For each, the difference from the distance between the corresponding atoms in the related chain is found. LSSR applies a restraint penalty on each difference. A functional form that reaches a plateau for large differences is used to avoid the restraints distorting parts of the structure that are not similar. Because LSSR are local, there is no need to separate out domains. Some restraint pruning is still necessary, but this has been automated. LSSR have been available to academic users of BUSTER since 2009 with the easy-to-use -autoncs and -target target.pdb options. The use of LSSR is illustrated in the re-refinement of PDB entries 5rnt, where -target enables the correct ligand-binding structure to be found, and 1osg, where -autoncs contributes to the location of an additional copy of the cyclic peptide ligand.

Adaptive Mesh Refinement for Microelectronic Device Design

NASA Technical Reports Server (NTRS)

Cwik, Tom; Lou, John; Norton, Charles

1999-01-01

Finite element and finite volume methods are used in a variety of design simulations when it is necessary to compute fields throughout regions that contain varying materials or geometry. Convergence of the simulation can be assessed by uniformly increasing the mesh density until an observable quantity stabilizes. Depending on the electrical size of the problem, uniform refinement of the mesh may be computationally infeasible due to memory limitations. Similarly, depending on the geometric complexity of the object being modeled, uniform refinement can be inefficient since regions that do not need refinement add to the computational expense. In either case, convergence to the correct (measured) solution is not guaranteed. Adaptive mesh refinement methods attempt to selectively refine the region of the mesh that is estimated to contain proportionally higher solution errors. The refinement may be obtained by decreasing the element size (h-refinement), by increasing the order of the element (p-refinement) or by a combination of the two (h-p refinement). A successful adaptive strategy refines the mesh to produce an accurate solution measured against the correct fields without undue computational expense. This is accomplished by the use of a) reliable a posteriori error estimates, b) hierarchal elements, and c) automatic adaptive mesh generation. Adaptive methods are also useful when problems with multi-scale field variations are encountered. These occur in active electronic devices that have thin doped layers and also when mixed physics is used in the calculation. The mesh needs to be fine at and near the thin layer to capture rapid field or charge variations, but can coarsen away from these layers where field variations smoothen and charge densities are uniform. This poster will present an adaptive mesh refinement package that runs on parallel computers and is applied to specific microelectronic device simulations. Passive sensors that operate in the infrared portion of

The Cross-Sectional Association between Consumption of the Recommended Five Food Group "Grain (Cereal)", Dietary Fibre and Anthropometric Measures among Australian Adults.

PubMed

Fayet-Moore, Flavia; Petocz, Peter; McConnell, Andrew; Tuck, Kate; Mansour, Marie

2017-02-18

The Australian Dietary Guidelines recommended "grain (cereal)" core food group includes both refined and whole grain foods, but excludes those that are discretionary (i.e., cakes). We investigated the association between daily serves from the "grain (cereal)" group and its effect on fibre and adiposity. Data from Australian adults in the 2011-2012 National Nutrition and Physical Activity Survey were used ( n = 9341). Participants were categorised by serves of core grain foods and general linear models were used to investigate the effect of demographic, socioeconomic, and dietary covariates on waist circumference, body mass index (BMI) and fibre intake. Compared to core grain avoiders (0 serves), high consumers (6+ serves/day) were: more likely male and socially advantaged, had a healthier dietary pattern, less likely dieting, overweight or obese, and were at lower risk of metabolic complications. After adjustment for age, sex and energy intake, there was an inverse relationship between core grain serves intake and BMI ( p < 0.001), waist circumference ( p = 0.001) and a positive relationship with fibre ( p < 0.001). Model adjustments for diet and lifestyle factors resulted in a smaller difference in waist circumference ( p = 0.006) and BMI ( p = 0.006). Core grain serves was significantly associated with higher fibre, but marginally clinically significant for lower adiposity.

Effects of film growth kinetics on grain coarsening and grain shape.

PubMed

Reis, F D A Aarão

2017-04-01

We study models of grain nucleation and coarsening during the deposition of a thin film using numerical simulations and scaling approaches. The incorporation of new particles in the film is determined by lattice growth models in three different universality classes, with no effect of the grain structure. The first model of grain coarsening is similar to that proposed by Saito and Omura [Phys. Rev. E 84, 021601 (2011)PLEEE81539-375510.1103/PhysRevE.84.021601], in which nucleation occurs only at the substrate, and the grain boundary evolution at the film surface is determined by a probabilistic competition of neighboring grains. The surface grain density has a power-law decay, with an exponent related to the dynamical exponent of the underlying growth kinetics, and the average radius of gyration scales with the film thickness with the same exponent. This model is extended by allowing nucleation of new grains during the deposition, with constant but small rates. The surface grain density crosses over from the initial power law decay to a saturation; at the crossover, the time, grain mass, and surface grain density are estimated as a function of the nucleation rate. The distributions of grain mass, height, and radius of gyration show remarkable power law decays, similar to other systems with coarsening and particle injection, with exponents also related to the dynamical exponent. The scaling of the radius of gyration with the height h relative to the base of the grain show clearly different exponents in growth dominated by surface tension and growth dominated by surface diffusion; thus it may be interesting for investigating the effects of kinetic roughening on grain morphology. In growth dominated by surface diffusion, the increase of grain size with temperature is observed.

Refined structure of dimeric diphtheria toxin at 2.0 A resolution.

PubMed Central

Bennett, M. J.; Choe, S.; Eisenberg, D.

1994-01-01

The refined structure of dimeric diphtheria toxin (DT) at 2.0 A resolution, based on 37,727 unique reflections (F > 1 sigma (F)), yields a final R factor of 19.5% with a model obeying standard geometry. The refined model consists of 523 amino acid residues, 1 molecule of the bound dinucleotide inhibitor adenylyl 3'-5' uridine 3' monophosphate (ApUp), and 405 well-ordered water molecules. The 2.0-A refined model reveals that the binding motif for ApUp includes residues in the catalytic and receptor-binding domains and is different from the Rossmann dinucleotide-binding fold. ApUp is bound in part by a long loop (residues 34-52) that crosses the active site. Several residues in the active site were previously identified as NAD-binding residues. Glu 148, previously identified as playing a catalytic role in ADP-ribosylation of elongation factor 2 by DT, is about 5 A from uracil in ApUp. The trigger for insertion of the transmembrane domain of DT into the endosomal membrane at low pH may involve 3 intradomain and 4 interdomain salt bridges that will be weakened at low pH by protonation of their acidic residues. The refined model also reveals that each molecule in dimeric DT has an "open" structure unlike most globular proteins, which we call an open monomer. Two open monomers interact by "domain swapping" to form a compact, globular dimeric DT structure. The possibility that the open monomer resembles a membrane insertion intermediate is discussed. PMID:7833807

Electrical properties of polycrystalline olivine: evidence for grain boundary transport

NASA Astrophysics Data System (ADS)

Ten Grotenhuis, S. M.; Drury, M. R.; Peach, C. J.; Spiers, C. J.

2003-12-01

The physical and chemical properties of grain boundaries are known to play an important role in determining the electrical properties of polycrystalline oxides. Grain boundaries can either enhance conductivity if the transport of charge carriers along the grain boundaries is faster than through the lattice, or grain boundaries can reduce conductivity if the grain boundaries block the transport of charge carriers. The purpose of the experiments presented here is to deduce the mechanisms responsible for electrical conductivity in fine-grained forsterite, the Mg-end member of olivine, in order to get a better understanding of the contribution of grain boundary transport, of the properties of the grain boundaries, and to determine any relation between grain size and conductivity. A relationship between grain size and conductivity at high temperature could potentially be used to interpret zones of anomalous conductivity in the upper mantle. The materials studied consist of fine-grained forsterite (Mg2SiO4) with a minor amount (5%) of enstatite (MgSiO3) added. The electrical conductivity of three melt-free synthetic polycrystalline samples, with grain sizes between 1.1 and 4.7 mm, was measured at temperatures up to 1470° C. The complex impedance plots display one clear arc, indicating a single dominant conduction mechanism. Bulk conductivity is inversely proportional to the grain size of the different samples. This relation suggests that grain boundary diffusion of the charge carriers is controlling the electrical conductivity of the samples. The activation energy for diffusion of the charge carriers lies between 315 and 323 kJ/mol. This resembles previous data on grain boundary diffusion of Mg in forsterite and grain boundary diffusion creep. A geometrical model of less conducting cubic grains and more conducting grain boundaries agrees well with the experimental data. This model is applied to a natural mantle shear zone to predict the conductivity contrast between

Grain boundary, triple junction and quadruple point mobility controlled normal grain growth

NASA Astrophysics Data System (ADS)

Rios, P. R.; Glicksman, M. E.

2015-07-01

Reduction in stored free energy provides the thermodynamic driving force for grain and bubble growth in polycrystals and foams. Evolution of polycrystalline networks exhibit the additional complication that grain growth may be controlled by several kinetic mechanisms through which the decrease in network energy occurs. Polyhedral boundaries, triple junctions (TJs), and quadruple points (QPs) are the geometrically distinct elements of three dimensional networks that follow Plateau's rules, provided that grain growth is limited by diffusion through, and motion of, cell boundaries. Shvindlerman and co-workers have long recognized the kinetic influences on polycrystalline grain growth of network TJs and QPs. Moreover, the emergence of interesting polycrystalline nanomaterials underscored that TJs can indeed influence grain growth kinetics. Currently there exist few detailed studies concerned either with network distributions of grain size, number of faces per grain, or with 'grain trajectories', when grain growth is limited by the motion of its TJs or QPs. By contrast there exist abundant studies of classical grain growth limited by boundary mobility. This study is focused on a topological/geometrical representation of polycrystals to obtain statistical predictions of the grain size and face number distributions, as well as growth 'trajectories' during steady-state grain growth. Three limits to grain growth are considered, with grain growth kinetics controlled by boundary, TJ, and QP mobilities.

48 CFR 208.7304 - Refined precious metals.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Refined precious metals... Government-Owned Precious Metals 208.7304 Refined precious metals. See PGI 208.7304 for a list of refined precious metals managed by DSCP. [71 FR 39005, July 11, 2006] ...

48 CFR 208.7304 - Refined precious metals.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Refined precious metals... Government-Owned Precious Metals 208.7304 Refined precious metals. See PGI 208.7304 for a list of refined precious metals managed by DSCP. [71 FR 39005, July 11, 2006] ...

Grain dissection as a grain size reducing mechanism during ice microdynamics

NASA Astrophysics Data System (ADS)

Steinbach, Florian; Kuiper, Ernst N.; Eichler, Jan; Bons, Paul D.; Drury, Martin R.; Griera, Albert; Pennock, Gill M.; Weikusat, Ilka

2017-04-01

Ice sheets are valuable paleo-climate archives, but can lose their integrity by ice flow. An understanding of the microdynamic mechanisms controlling the flow of ice is essential when assessing climatic and environmental developments related to ice sheets and glaciers. For instance, the development of a consistent mechanistic grain size law would support larger scale ice flow models. Recent research made significant progress in numerically modelling deformation and recrystallisation mechanisms in the polycrystalline ice and ice-air aggregate (Llorens et al., 2016a,b; Steinbach et al., 2016). The numerical setup assumed grain size reduction is achieved by the progressive transformation of subgrain boundaries into new high angle grain boundaries splitting an existing grain. This mechanism is usually termed polygonisation. Analogue experiments suggested, that strain induced grain boundary migration can cause bulges to migrate through the whole of a grain separating one region of the grain from another (Jessell, 1986; Urai, 1987). This mechanism of grain dissection could provide an alternative grain size reducing mechanism, but has not yet been observed during ice microdynamics. In this contribution, we present results using an updated numerical approach allowing for grain dissection. The approach is based on coupling the full field theory crystal visco-plasticity code (VPFFT) of Lebensohn (2001) to the multi-process modelling platform Elle (Bons et al., 2008). VPFFT predicts the mechanical fields resulting from short strain increments, dynamic recrystallisation process are implemented in Elle. The novel approach includes improvements to allow for grain dissection, which was topologically impossible during earlier simulations. The simulations are supported by microstructural observations from NEEM (North Greenland Eemian Ice Drilling) ice core. Mappings of c-axis orientations using the automatic fabric analyser and full crystallographic orientations using electron

Whole grains and health: from theory to practice--highlights of The Grains for Health Foundation's Whole Grains Summit 2012.

PubMed

McKeown, Nicola M; Jacques, Paul F; Seal, Chris J; de Vries, Jan; Jonnalagadda, Satya S; Clemens, Roger; Webb, Densie; Murphy, Lee Anne; van Klinken, Jan-Willem; Topping, David; Murray, Robyn; Degeneffe, Dennis; Marquart, Leonard F

2013-05-01

The Grains for Health Foundation's Whole Grains Summit, held May 19-22, 2012 in Minneapolis, was the first meeting of its kind to convene >300 scientists, educators, food technologists, grain breeders, food manufacturers, marketers, health professionals, and regulators from around the world. Its goals were to identify potential avenues for collaborative efforts and formulate new approaches to whole-grains research and health communications that support global public health and business. This paper summarizes some of the challenges and opportunities that researchers and nutrition educators face in expanding the knowledge base on whole grains and health and in translating and disseminating that knowledge to consumers. The consensus of the summit was that effective, long-term, public-private partnerships are needed to reach across the globe and galvanize the whole-grains community to collaborate effectively in translating whole-grains science into strategies that increase the availability and affordability of more healthful, grain-based food products. A prerequisite of that is the need to build trust among diverse multidisciplinary professionals involved in the growing, producing, marketing, and regulating of whole-grain products and between the grain and public health communities.

Refined sugar intake in Australian children.

PubMed

Somerset, Shawn M

2003-12-01

To estimate the intake of refined sugar in Australian children and adolescents, aged 2-18 years. Foods contributing to total sugar intake were identified using data from the National Nutrition Survey 1995 (NNS95), the most recent national dietary survey of the Australian population. The top 100 foods represented means of 85% (range 79-91%) and 82% (range 78-85%) of total sugar intake for boys and girls, respectively. Using published Australian food composition data (NUTTAB95), the proportion of total sugar being refined sugar was estimated for each food. Where published food composition data were not available, calculations from ingredients and manufacturer's information were used. The NNS95 assessed the dietary intake of a random sample of the Australian population, aged 2-18 years (n=3007). Mean daily intakes of refined sugar ranged from 26.9 to 78.3 g for 2-18-year-old girls, representing 6.6-14.8% of total energy intake. Corresponding figures for boys were 27.0 to 81.6 g and 8.0-14.0%, respectively. Of the 10 highest sources of refined sugar for each age group, sweetened beverages, especially cola-type beverages, were the most prominent. Refined sugar is an important contributor to dietary energy in Australian children. Sweetened beverages such as soft drinks and cordials were substantial sources of refined sugar and represent a potential target for campaigns to reduce refined sugar intake. Better access to information on the amounts of sugar added to processed food is essential for appropriate monitoring of this important energy source.

Microstructure Refinement and Mechanical Properties of 304 Stainless Steel by Repetitive Thermomechanical Processing

NASA Astrophysics Data System (ADS)

Al-Fadhalah, Khaled; Aleem, Muhammad

2018-04-01

Repetitive thermomechanical processing (TMP) was applied for evaluating the effect of strain-induced α'-martensite transformation and reversion annealing on microstructure refinement and mechanical properties of 304 austenitic stainless steel. The first TMP scheme consisted of four cycles of tensile deformation to strain of 0.4, while the second TMP scheme applied two cycles of tensile straining to 0.6. For both schemes, tensile tests were conducted at 173 K (- 100 °C) followed by 5-minute annealing at 1073 K (800 °C). The volume fraction of α'-martensite in deformed samples increased with increasing cycles, reaching a maximum of 98 vol pct. Examination of annealed microstructure by electron backscattered diffraction indicated that increasing strain and/or number of cycles resulted in stronger reversion to austenite with finer grain size of 1 μm. Yet, increasing strain reduced the formation of Σ3 boundaries. The annealing textures generally show reversion of α'-martensite texture components to the austenite texture of brass and copper orientations. The increase in strain and/or number of cycles resulted in stronger intensity of copper orientation, accompanied by the formation of recrystallization texture components of Goss, cube, and rotated cube. The reduction in grain size with increasing cycles caused an increase in yield strength. It also resulted in an increase in strain hardening rate during deformation due to the increase in the formation of α'-martensite. The increase in strain hardening rate occurred in two consecutive stages, marked as stages II and III. The strain hardening in stage II is due to the formation of α'-martensite from either austenite or ɛ-martensite, while the stage-III strain hardening is attributed to the necessity to break the α'-martensite-banded structure for forming block-type martensite at high strains.

Effects of grain size on the properties of bulk nanocrystalline Co-Ni alloys

NASA Astrophysics Data System (ADS)

Qiao, Gui-Ying; Xiao, Fu-Ren

2017-08-01

Bulk nanocrystalline Co78Ni22 alloys with grain size ranging from 5 nm to 35 nm were prepared by high-speed jet electrodeposition (HSJED) and annealing. Microhardness and magnetic properties of these alloys were investigated by microhardness tester and vibrating sample magnetometer. Effects of grain size on these characteristics were also discussed. Results show that the microhardness of nanocrystalline Co78Ni22 alloys increases following a d -1/2-power law with decreasing grain size d. This phenomenon fits the Hall-Petch law when the grain size ranges from 5 nm to 35 nm. However, coercivity H c increases following a 1/d-power law with increasing grain size when the grain size ranges from 5 nm to 15.9 nm. Coercivity H c decreases again for grain sizes above 16.6 nm according to the d 6-power law.

Modulus spectroscopy of grain-grain boundary binary system

NASA Astrophysics Data System (ADS)

Cheng, Peng-Fei; Song, Jiang; Li, Sheng-Tao; Wang, Hui

2015-02-01

Understanding various polarization mechanisms in complex dielectric systems and specifying their physical origins are key issues in dielectric physics. In this paper, four different methods for representing dielectric properties were analyzed and compared. Depending on the details of the system under study, i.e., uniform or non-uniform, it was suggested that different representing approaches should be used to obtain more valuable information. Especially, for the grain-grain boundary binary non-uniform system, its dielectric response was analyzed in detail in terms of modulus spectroscopy (MS). Furthermore, it was found that through MS, the dielectric responses between uniform and non-uniform systems, grain and grain boundary, Maxwell-Wagner polarization and intrinsic polarization can be distinguished. Finally, with the proposed model, the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics were studied. The colossal dielectric constant of CCTO at low frequency was attributed to the pseudo relaxation process of grain.

A Comparative Study on the Microstructure and Mechanical Properties of Cu6Sn5 and Cu3Sn Joints Formed by TLP Soldering With/Without the Assistance of Ultrasonic Waves

NASA Astrophysics Data System (ADS)

Zhao, H. Y.; Liu, J. H.; Li, Z. L.; Song, X. G.; Zhao, Y. X.; Niu, H. W.; Tian, H.; Dong, H. J.; Feng, J. C.

2018-07-01

In this study, the microstructure and mechanical properties of Cu6Sn5 and Cu3Sn intermetallic joints, formed by the transient liquid phase (TLP) soldering process with and without the assistance of ultrasonic waves (USWs), were compared. After the application of USWs in the TLP soldering process, Cu-Sn intermetallic compounds (IMCs) exhibited a novel noninterfacial growth pattern in the molten solder interlayer. The resulting Cu6Sn5 and Cu3Sn joints consisted of refined equiaxed IMC grains with average sizes of 3 and 2.3 µm, respectively. The Cu6Sn5 grains in the ultrasonically soldered intermetallic joints demonstrated uniform mechanical properties with elastic modulus and hardness values of 123.0 and 5.98 GPa, respectively, while those of Cu3Sn grains were 133.9 and 5.08 GPa, respectively. The shear strengths of ultrasonically soldered Cu6Sn5 and Cu3Sn joints were measured to be 60 and 65 MPa, respectively, higher than that for reflow-soldered intermetallic joints. Ultrasonically soldered Cu6Sn5 and Cu3Sn joints both exhibited a combination of transgranular and intergranular fractures during shear testing.

A Comparative Study on the Microstructure and Mechanical Properties of Cu6Sn5 and Cu3Sn Joints Formed by TLP Soldering With/Without the Assistance of Ultrasonic Waves

NASA Astrophysics Data System (ADS)

Zhao, H. Y.; Liu, J. H.; Li, Z. L.; Song, X. G.; Zhao, Y. X.; Niu, H. W.; Tian, H.; Dong, H. J.; Feng, J. C.

2018-05-01

In this study, the microstructure and mechanical properties of Cu6Sn5 and Cu3Sn intermetallic joints, formed by the transient liquid phase (TLP) soldering process with and without the assistance of ultrasonic waves (USWs), were compared. After the application of USWs in the TLP soldering process, Cu-Sn intermetallic compounds (IMCs) exhibited a novel noninterfacial growth pattern in the molten solder interlayer. The resulting Cu6Sn5 and Cu3Sn joints consisted of refined equiaxed IMC grains with average sizes of 3 and 2.3 µm, respectively. The Cu6Sn5 grains in the ultrasonically soldered intermetallic joints demonstrated uniform mechanical properties with elastic modulus and hardness values of 123.0 and 5.98 GPa, respectively, while those of Cu3Sn grains were 133.9 and 5.08 GPa, respectively. The shear strengths of ultrasonically soldered Cu6Sn5 and Cu3Sn joints were measured to be 60 and 65 MPa, respectively, higher than that for reflow-soldered intermetallic joints. Ultrasonically soldered Cu6Sn5 and Cu3Sn joints both exhibited a combination of transgranular and intergranular fractures during shear testing.

The Role of Grain Boundary Energy on Grain Boundary Complexion Transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bojarski, Stephanie A.; Rohrer, Gregory S.

Grain boundary complexions are distinct equilibrium structures and compositions of a grain boundary and complexion transformations are transition from a metastable to an equilibrium complexion at a specific thermodynamic and geometric conditions. Previous work indicates that, in the case of doped alumina, a complexion transition that increased the mobility of transformed boundaries and resulted in abnormal grain growth also caused a decrease in the mean relative grain boundary energy as well as an increase in the anisotropy of the grain boundary character distribution (GBCD). The current work will investigate the hypothesis that the rates of complexion transitions that result inmore » abnormal grain growth (AGG) depend on grain boundary character and energy. Furthermore, the current work expands upon this understanding and tests the hypothesis that it is possible to control when and where a complexion transition occurs by controlling the local grain boundary energy distribution.« less

Differentiation of Bread Made with Whole Grain and Refined Wheat (T. aestivum) Flour Using LC/MS-based chromatographic Fingerprinting and Chemometric Approaches

USDA-ARS?s Scientific Manuscript database

A fuzzy chromatography mass spectrometric (FCMS) fingerprinting method combined with chemometric analysis was established to diffrentiate between whole wheat (WW) flours and refined wheat (RW) flour, and the breads made from them. The chemical compositions of the bread samples were profiled using h...

Coarse-Grained Molecular Dynamics Simulation of Ionic Polymer Networks

DTIC Science & Technology

2008-07-01

AFRL-RX-WP-TP-2009-4198 COARSE-GRAINED MOLECULAR DYNAMICS SIMULATION OF IONIC POLYMER NETWORKS (Postprint) T.E. Dirama, V. Varshney, K.L...GRAINED MOLECULAR DYNAMICS SIMULATION OF IONIC POLYMER NETWORKS (Postprint) 5a. CONTRACT NUMBER FA8650-05-D-5807-0052 5b. GRANT NUMBER 5c...We studied two types of networks which differ only by one containing ionic pairs that amount to 7% of the total number of bonds present. The stress

Study of variation grain size in desulfurization process of calcined petroleum coke

NASA Astrophysics Data System (ADS)

Pintowantoro, Sungging; Setiawan, Muhammad Arif; Abdul, Fakhreza

2018-04-01

Indonesia is a country with abundant natural resources, such as mineral mining and petroleum. In petroleum processing, crude oil can be processed into a source of fuel energy such as gasoline, diesel, oil, petroleum coke, and others. One of crude oil potentials in Indonesia is petroleum coke. Petroleum coke is a product from oil refining process. Sulfur reducing process in calcined petroleum cokes can be done by desulfurization process. The industries which have potential to become petroleum coke processing consumers are industries of aluminum smelting (anode, graphite block, carbon mortar), iron riser, calcined coke, foundry coke, etc. Sulfur reducing process in calcined petroleum coke can be done by thermal desulfurization process with alkaline substance NaOH. Desulfurization of petroleum coke process can be done in two ways, which are thermal desulfurization and hydrodesulphurization. This study aims to determine the effect of various grain size on sulfur, carbon, and chemical bond which contained by calcined petroleum coke. The raw material use calcined petroleum coke with 0.653% sulfur content. The grain size that used in this research is 50 mesh, then varied to 20 mesh and 100 mesh for each desulfurization process. Desulfurization are tested by ICP, UV-VIS, and FTIR to determine levels of sulfur, carbon, chemical bonding and sulfur dissolved water which contained in the residual washing of calcined petroleum coke. From various grain size that mentioned before, the optimal value is on 100 mesh grain size, where the sulfur content in petroleum coke is 0.24% and carbon content reaches the highest level of 97.8%. Meanwhile for grain size 100 mesh in the desulfurization process is enough to break the chemical bonds of organic sulfur in petroleum coke.

The Strength-Grain Size Relationship in Ultrafine-Grained Metals

NASA Astrophysics Data System (ADS)

Balasubramanian, N.; Langdon, Terence G.

2016-12-01

Metals processed by severe plastic deformation (SPD) techniques, such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the Hall-Petch (H-P) relationship. Examples of this behavior are discussed using experimental data for Ti, Al, and Ni. These materials typically have grain sizes greater than 50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. However, both high strength and high ductility may be achieved simultaneously by imposing high strain to obtain ultrafine-grain sizes and high fractions of high-angle grain boundaries. This facilitates grain boundary sliding, and an example is presented for a cast Al-7 pct Si alloy processed by HPT. In some materials, SPD may result in a weakening even with a very fine grain size, and this is due to microstructural changes during processing. Examples are presented for an Al-7034 alloy processed by ECAP and a Zn-22 pct Al alloy processed by HPT. In some SPD-processed materials, it is possible that grain boundary segregation and other features are present leading to higher strengths than predicted by the H-P relationship.

A template-based approach for parallel hexahedral two-refinement

DOE PAGES

Owen, Steven J.; Shih, Ryan M.; Ernst, Corey D.

2016-10-17

Here, we provide a template-based approach for generating locally refined all-hex meshes. We focus specifically on refinement of initially structured grids utilizing a 2-refinement approach where uniformly refined hexes are subdivided into eight child elements. The refinement algorithm consists of identifying marked nodes that are used as the basis for a set of four simple refinement templates. The target application for 2-refinement is a parallel grid-based all-hex meshing tool for high performance computing in a distributed environment. The result is a parallel consistent locally refined mesh requiring minimal communication and where minimum mesh quality is greater than scaled Jacobian 0.3more » prior to smoothing.« less

A template-based approach for parallel hexahedral two-refinement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Owen, Steven J.; Shih, Ryan M.; Ernst, Corey D.

Here, we provide a template-based approach for generating locally refined all-hex meshes. We focus specifically on refinement of initially structured grids utilizing a 2-refinement approach where uniformly refined hexes are subdivided into eight child elements. The refinement algorithm consists of identifying marked nodes that are used as the basis for a set of four simple refinement templates. The target application for 2-refinement is a parallel grid-based all-hex meshing tool for high performance computing in a distributed environment. The result is a parallel consistent locally refined mesh requiring minimal communication and where minimum mesh quality is greater than scaled Jacobian 0.3more » prior to smoothing.« less

Separation of CsCl and SrCl2 from a ternary CsCl-SrCl2-LiCl via a zone refining process for waste salt minimization of pyroprocessing

NASA Astrophysics Data System (ADS)

Shim, Moonsoo; Choi, Ho Gil; Yi, Kyung Woo; Hwang, Il Soon; Lee, Jong Hyeon

2016-11-01

The purification of LiCl salt mixture has traditionally been carried out by a melt crystallization process. To improve the throughput of zone refining, three heaters were installed in the zone refiner. The zone refining method was used to grow pure LiCl salt ingots from LiCl-CsCl-SrCl2 salt mixture. The main investigated parameters were the heater speed and the number of passes. A change in the LiCl crystal grain size was observed according to the horizontal direction. From each zone refined salt ingot, samples were collected horizontally. To analyze the concentrations of Sr and Cs, an inductively coupled plasma optical emission spectrometer and inductively coupled plasma mass spectrometer were used, respectively. The experimental results show that Sr and Cs concentrations at the initial region of the ingot were low and reached their peak at the final freezing region of the salt ingot. Concentration results of zone refined salt were compared with theoretical results yielded by the proposed model to validate its predictions. The keff of Sr and Cs were 0.13 and 0.11, respectively. The decontamination factors of Sr and Cs were 450 and 1650, respectively.

Core–shell grain structures and ferroelectric properties of Na0.5K0.5NbO3–LiTaO3–BiScO3 piezoelectric ceramics

PubMed Central

Zhu, Fangyuan; Ward, Michael B.; Li, Jing-Feng; Milne, Steven J.

2015-01-01

Legislation arising from health and environmental concerns has intensified research into finding suitable alternatives to lead-based piezoceramics. Recently, solid solutions based on sodium potassium niobate (K,Na)NbO3 (KNN) have become one of the globally-important lead-free counterparts, due to their favourable dielectric and piezoelectric properties. This data article provides information on the ferroelectric properties and core–shell grain structures for the system, (1−y)[(1−x)Na0.5K0.5NbO3 – xLiTaO3] – yBiScO3 (x=0–0.1, y=0.02, abbreviated as KNN–xLT–2BS). We show elemental analysis with aid of TEM spot-EDX to identify three-type grain-types in the KNN–LT–BS ternary system. Melting behaviour has been assessed using a tube furnace with build-in camera. Details for the ferroelectric properties and core–shell chemical segregation are illustrated. PMID:26217758

Fine-grained zirconium-base material

DOEpatents

Van Houten, G.R.

1974-01-01

A method is described for making zirconium with inhibited grain growth characteristics, by the process of vacuum melting the zirconium, adding 0.3 to 0.5% carbon, stirring, homogenizing, and cooling. (Official Gazette)

Effect of Sm-Rich Phase on Corrosion Behavior of Hot-Extruded AZ31-1.5Sm Magnesium Alloy

NASA Astrophysics Data System (ADS)

Li, Xiao; Hu, Zhi; Yan, Hong; Wu, Xiaoquan; Xie, Hecong; Dong, Zhou

2018-05-01

The effects of Sm on the corrosion and microstructure behavior of hot-extruded AZ31 magnesium alloy were investigated by SEM, TEM, weight loss analysis, and electrochemical measurements. The results indicated that granular Al2Sm phase 4 μm in size in the hot-extruded AZ31 magnesium alloy modified with 1.5 wt.% Sm leads to significant grain refinement. The corrosion rate decreased from 15.98 × 10-4 to 11.19 × 10-4 g cm-2 h-1 in the transverse section and from 8.57 × 10-4 to 6.20 × 10-4 g cm-2 h-1 in the longitudinal section. Compared to the unmodified alloy, the corrosion potential of the Sm-modified alloy in the transverse and longitudinal sections increased by 98 and 62 mV, respectively, and the R ct value (charge transfer resistance) in the transverse and longitudinal sections of the modified alloy increased from 1764 and 1756 to 2928 and 2408 Ω cm2, respectively. The results showed that the corrosion resistance of hot-extruded AZ31 magnesium alloy was significantly improved by Sm addition due to the grain refinement, the decreased dislocation density, and the suppression of micro-galvanic corrosion caused by Al-Sm-(Mn) intermetallic compounds.