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1

Rapid cold hardening response in the predatory mite Neoseiulus californicus.  

PubMed

We investigated the rapid cold hardening (RCH) response in the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). On direct exposure, ?2 % of adult females survived -10 °C for 2 h. However, when acclimatized first at 5 °C for 1 h, 75 % of females survived. RCH could also be induced by acclimatization at 30 °C for 2 h or anoxia (oxygen-free nitrogen) for 1-2 h. All immature stages showed enhanced survival when acclimatized at 5 °C for 2 h before exposure to -10 °C. Acclimatization at 30 °C induced RCH only in eggs and deutonymphs, and anoxia was effective for eggs, larvae, and deutonymphs. The variability among immature stages may be attributed to the cost associated with the acclimatization treatments. Our findings suggest that RCH may promote the survival of N. californicus during unexpected changes in temperatures, and can be an important feature particularly when this natural enemy is introduced to non-native environments. PMID:24682616

Ghazy, Noureldin Abuelfadl; Amano, Hiroshi

2014-08-01

2

Rapid cold-hardening increases membrane fluidity and cold tolerance of insect cells.  

PubMed

The rapid cold-hardening (RCH) response not only confers dramatic protection against cold-shock (non-freezing) injury, but also "instantaneously" enhances organismal performance. Since cold-shock injury is associated with damage to the cell membrane, we investigated the relationship between RCH and changes in cold tolerance and membrane fluidity at the cellular level. None of the adult flies (Sarcophaga bullata) in the cold-shocked treatment group survived direct transfer to -8 degrees C for 2 h; in contrast, 64.5% of flies in the RCH group survived exposure to -8 degrees C. Differences between the treatment groups also were reflected at the cellular level; only 21.3% of fat body cells in the cold-shocked group survived compared to 68.5% in the RCH group. Using 31P solid-state NMR spectroscopy, we determined that membrane fluidity increased concurrently with rapid cold-hardening of fat body cells. This result suggests that membrane characteristics may be modified very rapidly to protect cells against cold-shock injury. PMID:16626678

Lee, Richard E; Damodaran, Krishnan; Yi, Shu-Xia; Lorigan, Gary A

2006-06-01

3

Rapid cold hardening in the predatory mite Euseius (Amblyseius) finlandicus (Acari: Phytoseiidae).  

PubMed

A rapid cold hardening response was studied in diapause and non-diapause females of the predatory mite Euseius finlandicus. When laboratory reared diapause and non-diapause females were transferred and maintained from the rearing temperature of 20 degrees C for 2 h to -11.5 degrees C and -10 degrees C, 10 to 20% survived respectively. However, conditioning of diapause females for 4 h at a range of temperatures from 0 to 10 degrees C before their exposure for 2 h to -11.5 degrees C, increased survival to approximately 90%. Similarly, conditioning of non-diapause females for 4 h at 5 degrees C before their exposure for 2 h to -10 degrees C increased survival to 90%. A similar rapid cold hardening response in both diapause and non-diapause females was also induced through gradual cooling of the mites, at a rate of approximately 0.4 degrees C per min. The rapid increase in cold tolerance after prior conditioning of the mites to low temperatures, was rapidly lost when they returned to a higher temperature of 20 degrees C. Rapid cold hardening extended the survival time of diapause and non-diapause females at sub-zero temperatures. The cost of rapid cold hardening in reproductive potential after diapause termination was negligible. In non-diapause females, however, the increase in cold tolerance gained through gradual cooling could not prevent cold shock injuries, as both fecundity and survival were reduced. PMID:11356416

Broufas, G D.; Koveos, D S.

2001-07-01

4

Rapid cold-hardening blocks cold-induced apoptosis by inhibiting the activation of pro-caspases in the flesh fly Sarcophaga crassipalpis  

Microsoft Academic Search

Apoptosis plays important roles in the selective elimination of sub-lethally damaged cells due to various environmental stresses.\\u000a The rapid cold-hardening (RCH) response protects insects from the otherwise lethal consequences of injury due to cold-shock.\\u000a We recently demonstrated that cold shock induces apoptotic cell death in insects and that RCH functions to specifically block\\u000a cold-shock-induced apoptosis. In the present study we

Shu-Xia YiRichard; Richard E. Lee

2011-01-01

5

Stage-related variation in rapid cold hardening as a test of the environmental predictability hypothesis.  

PubMed

The environmental predictability (EP) hypothesis proposes that rapid cold hardening (RCH) might be common in temperate species incapable of surviving freezing events and which also dwell in unpredictable environments. The kelp fly Paractora dreuxi serves as a useful model organism to test this prediction at an intra-specific level because larvae and adults show different responses to low temperature despite occupying a similar unpredictable thermal environment. Here, using acclimation temperatures, which simulated seasonal temperature variation, we find little evidence for RCH in the freeze-intolerant adults but a limited RCH response in freeze-tolerant larvae. In the relatively short-lived adults, survival of -11 degrees C generally did not improve after 2h pre-treatments at -4, -2, 0, 10, 20 or 25 degrees C either in summer- (10 degrees C) or winter (0 degrees C)-acclimated individuals. By contrast, survival of summer-acclimated larvae to -7.6 degrees C was significantly improved by approximately 37% and 30% with -2 and 0 degrees C pre-treatments, respectively. The finding that summer-acclimated larvae showed RCH whereas this was not the case in the winter-acclimated larvae partially supports the predictions of the EP hypothesis. However, the EP hypothesis also predicts that the adults should have demonstrated an RCH response, yet they did not do so. Rather, it seems likely that they avoid stressful environments by behavioural thermoregulation. Differences in responses among the adults and larvae are therefore to some extent predictable from differences in their feeding requirements and behaviour. These results show that further studies of RCH should take into account the way in which differences among life stages influence the interaction between phenotypic plasticity and environmental variability and predictability. PMID:17368475

Terblanche, John S; Marais, Elrike; Chown, Steven L

2007-05-01

6

The protective effect of rapid cold-hardening develops more quickly in frozen versus supercooled larvae of the Antarctic midge, Belgica antarctica.  

PubMed

During the austral summer, larvae of the terrestrial midge Belgica antarctica (Diptera: Chironomidae) experience highly variable and often unpredictable thermal conditions. In addition to remaining freeze tolerant year-round, larvae are capable of swiftly increasing their cold tolerance through the rapid cold-hardening (RCH) response. The present study compared the induction of RCH in frozen versus supercooled larvae. At the same induction temperature, RCH occurred more rapidly and conferred a greater level of cryoprotection in frozen versus supercooled larvae. Furthermore, RCH in frozen larvae could be induced at temperatures as low as -12°C, which is the lowest temperature reported to induce RCH. Remarkably, as little as 15 min at -5°C significantly enhanced larval cold tolerance. Not only is protection from RCH acquired swiftly, but it is also quickly lost after thawing for 2 h at 2°C. Because the primary difference between frozen and supercooled larvae is cellular dehydration caused by freeze concentration of body fluids, we also compared the effects of acclimation in dehydrated versus frozen larvae. Because slow dehydration without chilling significantly increased larval survival to a subsequent cold exposure, we hypothesize that cellular dehydration caused by freeze concentration promotes the rapid acquisition of cold tolerance in frozen larvae. PMID:23868837

Kawarasaki, Yuta; Teets, Nicholas M; Denlinger, David L; Lee, Richard E

2013-10-15

7

Short term hardening effects on survival of acute and chronic cold exposure by Drosophila melanogaster larvae  

PubMed Central

We quantified the variation and plasticity in cold tolerance among four larval stages of four laboratory strains of Drosophila melanogaster in response to both acute (<2 hours of cold exposure) and chronic (?7 hours of cold exposure) cold exposure. We observed significant differences in basal cold tolerance between the strains and among larval stages. Early larval instars were generally more tolerant of acute cold exposures than 3rd instar larvae. However, wandering larvae were more tolerant of chronic cold exposures than the other stages. Early stages also displayed a more pronounced rapid cold-hardening response than the later stages. Heat pre-treatment did not confer a significant increase in cold tolerance to any of the strains at any stage, pointing to different mechanisms being involved in resolving heat- and cold-elicited damage. However, when heat pre-treatment was combined with rapid cold-hardening as sequential pre-treatments, both positive (heat first) and negative (heat second) effects on cold tolerance were observed. We discuss possible mechanisms underlying cold-hardening and the effects of acute and chronic cold exposures.

Rajamohan, Arun; Sinclair, Brent J.

2008-01-01

8

Genetic study of glutathione accumulation during cold hardening in wheat  

Microsoft Academic Search

.   The effect of cold hardening on the accumulation of glutathione (GSH) and its precursors was studied in the shoots and roots\\u000a of wheat (Triticum aestivum L.) cv. Cheyenne (Ch, frost-tolerant) and cv. Chinese Spring (CS, moderately frost-sensitive), in a T. spelta L. accession (Tsp, frost-sensitive) and in chro- mosome substitution lines CS (Ch 5A) and CS (Tsp 5A). The

Gábor Kocsy; Gabriella Szalai; Attila Vágújfalvi; László Stéhli; György Orosz; Gábor Galiba

2000-01-01

9

Effects of photoperiodically induced reproductive diapause and cold hardening on the cold tolerance of Drosophila montana.  

PubMed

Coping with seasonal and daily variation in environmental conditions requires that organisms are able to adjust their reproduction and stress tolerance according to environmental conditions. Females of Drosophila montana populations have adapted to survive over the dark and cold winters at high latitudes and altitudes by spending this season in photoperiodically controlled reproductive diapause and reproducing only in spring/summer. The present study showed that flies of a northern population of this species are quite tolerant of low temperatures and show high seasonal and short-term plasticity in this trait. Culturing the flies in short day length (nearly all females in reproductive diapause), as well as allowing the flies to get cold hardened before the cold treatment, increased the cold tolerance of both sexes both in chill coma recovery time test and in mortality assay. Chill coma recovery time test performed for the females of two additional D. montana populations cultured in a day length where about half of the females enter diapause, also showed that diapause can increase female cold tolerance even without a change in day length. Direct linkage between diapause and cold tolerance was found in only two strains representing a high-altitude population of the species, but the phenomenon will certainly be worth of studying in northern and southern populations of the species with larger data sets. PMID:20932841

Vesala, Laura; Hoikkala, Anneli

2011-01-01

10

Strain hardening of heavily cold-worked metals  

SciTech Connect

It is demonstrated that strain hardening in torsion cannot be correlated with axisymmetric deformation by the von Mises effective stress strain criterion. In fcc materials, the flow stress levels and strain hardening rates are typically lower in torsion and saturation, only at lower stress levels. In bcc iron, a low saturtion stress is observed for torsion, whereas linear hardening is observed for axisymmetric extension. Much of the discrepancy in flow curves can be explained by texture. It is demonstrated that a crystallographic effective stress-strain criterion based on evolving average Taylor factors provides the proper magnitude correction for torsional flow curves in fcc materials. The simple crystallographic analysis does not fully explain the hardening response following deformation path changes and multidirectional loading. 96 references, 42 figures.

Hecker, S.S.; Stout, M.G.

1982-01-01

11

Solute Diffusion Characteristics of a Rapid Hardening Al-Cu-Mg Alloy during the Early Stages of Age Hardening  

NASA Astrophysics Data System (ADS)

The heat-transfer characteristics of a rapid hardening Al-1.1Cu-1.7Mg at. pct alloy during the early stages of age hardening have been tested, both by experiment and finite element modeling, for a typical laboratory-scale sample, and subsequently a maximum diffusion distance by random walk has been calculated for the solute atom species. It is found that due to small diffusion distances compared to the average dislocation loop interspacing, the dislocation-locking hardness mechanism is not likely, and rather, the cluster hardening model is more accurate.

Marceau, R. K. W.; Tsafnat, N.; Haley, D.; Ringer, S. P.

2010-08-01

12

VSP accumulation and cold-inducible gene expression during autumn hardening and overwintering of alfalfa  

Microsoft Academic Search

This study describes the time-course of the accumu- lation of total soluble proteins (TSPs) and vegetative storage proteins (VSPs) and of the transcripts of cold- inducible (CI) and VSP-encoding genes in taproots of two alfalfa cultivars (AC Caribou and Europe) during their acclimation to natural autumn hardening and overwintering conditions in eastern Canada. The im- pact of a defoliation in

Catherine Dhont; Yves Castonguay; Jean-Christophe Avice

2006-01-01

13

Intergranular Cracking in High-Strength, Cold-Rolled, and Precipitation- Hardened Austenitic Stainless Steel UNS S35500.  

National Technical Information Service (NTIS)

When quench annealed, stainless steel UNS 35500 (C 0.12, Cr 15.5, Ni 4.5, Mo 3, N 0.1%) is austenitic and soft. In cold-rolled and tempered condition, heavy cold rolling followed by precipitation hardening considerably strengthens the material (UTS 220 ks...

S. P. Pednekar V. K. Champagne M. S. Pepi S. Grendhal

1999-01-01

14

Changes in gene expression during dehardening of cold-hardened winter rye ( Secale cereale L.) leaves and potential role of a peptide methionine sulfoxide reductase in cold-acclimation  

Microsoft Academic Search

Suppression subtractive hybridization and differential display polymerase chain reactions were used to identify genes that were differentially expressed in cold-hardened and dehardened leaves of winter rye (Secale cereale L.). The transcripts of nine genes declined during dehardening at 22°C of cold-hardened 4°C-grown leaves, indicating some role in cold-acclimation. Among the genes that were strongly expressed in cold-hardened leaves were five

Oliver In; Thomas Berberich; Skander Romdhane; Jürgen Feierabend

2005-01-01

15

Apoplastic Sugars, Fructans, Fructan Exohydrolase, and Invertase in Winter Oat: Responses to Second-Phase Cold Hardening  

PubMed Central

Changes in apoplastic carbohydrate concentrations and activities of carbohydrate-degrading enzymes were determined in crown tissues of oat (Avena sativa L., cv Wintok) during cold hardening. During second-phase hardening (?3°C for 3 d) levels of fructan, sucrose, glucose, and fructose in the apoplast increased significantly above that in nonhardened and first-phase-hardened plants. The extent of the increase in apoplastic fructan during second-phase hardening varied with the degree of fructan polymerization (DP) (e.g. DP3 and DP4 increased to a greater extent than DP7 and DP > 7). Activities of invertase and fructan exohydrolase in the crown apoplast increased approximately 4-fold over nonhardened and first-phase-hardened plants. Apoplastic fluid extracted from nonhardened, first-phase-hardened, and second-phase-hardened crown tissues had low levels, of symplastic contamination, as determined by malate dehydrogenase activity. The significance of these results in relation to increases in freezing tolerance from second-phase hardening is discussed.

Livingston, David P.; Henson, Cynthia A.

1998-01-01

16

Rapid solution hardening at elevated temperatures by substitutional Re alloying in MoSi{sub 2}  

SciTech Connect

The mechanical properties of solidification processed polycrystalline MoSi{sub 2} and ternary (Mo, Re)Si{sub 2} alloys were evaluated by compression testing at elevated temperatures. Rhenium is found to be a potent solid solution hardening addition to C11{sub b} MoSi{sub 2} at temperatures up to 1,600 C (highest temperature used in the study). Dislocation microstructures, characterized by electron microscopy, are consistent with the significant hardening exhibited by Re containing alloys. The high hardening rate cannot be explained by the classical substitutional solid solution hardening theories for metals based on atomic size misfit and elastic moduli mismatch. Since rhenium disilicide is semiconducting had has a Si-deficient stoichiometry of ReSi{sub 1.75}, the addition of Re to MoSi{sub 2} may lead to the formation of constitutional Si vacancies which may pair with Re substitutionals to form point defect complexes. A model that describes the elliptical strain field (tetragonal distortion) around these point defects is used to interpret the rapid hardening by Re in MoSi{sub 2}. Small additions of Re may provide the necessary high temperature strength in MoSi{sub 2}-based structural intermetallic alloys for very high temperature applications ({approximately}1,200--1,600 C).

Misra, A.; Sharif, A.A.; Petrovic, J.J.; Mitchell, T.E.

2000-02-25

17

The investigation of basic processes of rapidly hardening wood-cement-water mixture with CO 2  

Microsoft Academic Search

The rapid hardening of wood-cement-water mixture in a carbon dioxide enriched environment\\u000a was investigated, by studying the development of carbonation degree and monitoring the phase changes\\u000a in the mixture. The carbonation reaction was a diffusion-controlled process. It occurred very\\u000a quickly in the first two minutes of reaction. After that, its rate decreased drastically, due to the\\u000a increasing difficulty of transporting reactants to

Hucheng Qi; Paul A. Cooper; Doug Hooton

2010-01-01

18

Effect of light on the gene expression and hormonal status of winter and spring wheat plants during cold hardening.  

PubMed

The effect of light on gene expression and hormonal status during the development of freezing tolerance was studied in winter wheat (Triticum aestivum var. Mv Emese) and in the spring wheat variety Nadro. Ten-day-old plants (3-leaf stage) were cold hardened at 5°C for 12 days under either normal (250 ľmol m(-2) s(-1) ) or low (20 ľmol m(-2) s(-1) ) light conditions. Comprehensive analysis was carried out to explore the background of frost tolerance and the differences between these wheat varieties. Global genome analysis was performed, enquiring about the details of the cold signaling pathways. The expression level of a large number of genes is affected by light, and this effect may differ in different wheat genotypes. Photosynthesis-related processes probably play a key role in the enhancement of freezing tolerance; however, there are several other genes whose induction is light-dependent, so either there is cross-talk between signaling of chloroplast originating and other protective mechanisms or there are other light sensors that transduce signals to the components responsible for stress tolerance. Changes in the level of both plant hormones (indole-3-acetic acid, cytokinins, nitric oxide and ethylene precursor 1-aminocyclopropane-1-carboxylic acid) and other stress-related protective substances (proline, phenolics) were investigated during the phases of the hardening period. Hormonal levels were also affected by light and their dynamics indicate that wheat plants try to keep growing during the cold-hardening period. The data from this experiment may provide a new insight into the cross talk between cold and light signaling in wheat. PMID:22257084

Majláth, Imre; Szalai, Gabriella; Soós, Vilmos; Sebestyén, Endre; Balázs, Ervin; Vanková, Radomíra; Dobrev, Petre I; Tari, Irma; Tandori, Júlia; Janda, Tibor

2012-06-01

19

Primary and secondary metabolism of winter wheat under cold hardening and treatment with antioxidants  

Microsoft Academic Search

The content of saccharides and phenolic compounds (including flavonoids and lignin) and the activity of L-phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) were determined in leaves and tillering nodes of winter wheat Triticum aestivum L.) cultivars Inna and Moskovskaya 39, differing in the level of frost resistance. These parameters were determined in three\\u000a groups of plants—control, hardened, and treated with synthetic antioxidants

N. A. Olenichenko; N. V. Zagoskina; N. V. Astakhova; T. I. Trunova; Yu. V. Kuznetsov

2008-01-01

20

Spin-Probe Studies during Freezing of Cells Isolated from Cold-Hardened and Nonhardened Winter Rye 12  

PubMed Central

Mesophyll cells isolated from cold-hardened and nonhardened winter rye (Secale cereale L. cv. Puma) were spin-labeled with the fatty-acid spin probe N-oxyl-4,4-dimethyloxazolidine 5-ketostearic acid. The probe was intercalated within the cellular membranes and changes in probe motion were followed during extracellular freezing of the cells. A correlation was observed between the lethal freezing temperatures (LT50) of the cells and the maximum hyperfine splitting value achieved by the incorporated probe. Rigid limit spectra indicated that a more ordered average packing was attained by membranes of hardened cells which survived freezing to lower temperatures. Nonhardened cells fixed with osmic acid at lethal freezing temperatures, in the frozen state, showed both conversion of normal bilayered cellular membrane ultrastructure to an amorphous state and condensation of cellular membranes to form densely packed multibilayered vesicles. Taken together with the spin-labeling data, these results suggest that at least one molecular mechanism of extracellular freezing injury involves the irreversible conversion of planar membrane bilayers to structures having less ordered packing and increased surface curvatures. Images

Singh, Jas; Miller, Richard W.

1982-01-01

21

A semi-physiological model of cold hardening and dehardening in walnut stem.  

PubMed

It has been hypothesized that the increase in temperature in this century could lead to an increase in frost damage to plant tissues. Several models have been proposed to describe the development of cold hardiness, but never taking into account extreme climatic and/or physiological events. Our results on walnut tree (Juglans regia L.) show that cold hardiness was best correlated with average daily temperatures minimal temperatures over the last 15 days before sampling (T(min 15 days)), indicating that the freezing tolerance depended on the tree's climatic history. Moreover, this study also shows that the accumulation of sucrose and the water content (WC) decrease are an essential step towards cold hardiness. Thus, a simple linear model based on climatic (T(min 15 days)) and physiological (soluble sugars, WC) explanatory variables was developed to predict the cold hardiness level in walnut stem at any time during the leafless period. Each of the three input variables can be assigned a specific role contributing to the simulated function, cold hardiness. The extent and robustness of this relation was assessed on extreme physiological events on walnut trees bearing three main branches. On each tree, one branch was defoliated to limit the local carbohydrate and transpiration, one was girdled to increase local carbohydrate and prevent carbohydrate export and the third one was kept untreated as control. As expected, these treatments impacted both local carbon reserves and WC in the stems born by each main branch in comparison with the control on the same tree. The impact of these treatments on stem's freezing tolerance, as evaluated by an electrolyte leakage method (LT??), confirmed the direct impact of soluble sugar and WC on cold hardiness over a wide range of carbohydrate and WC. This is discussed in relation to the branch autonomy theory for carbon but also for water during summer growth and winter periods. The present study demonstrates the importance of physiological parameters in the prediction of cold hardiness and proposes a way to model cold hardiness with extreme climatic and/or physiological events. PMID:21030404

Poirier, Magalie; Lacointe, André; Améglio, Thierry

2010-12-01

22

Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor  

PubMed Central

Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in relation to short and long term periods of cold followed by a brief frost treatment were studied in order to disclose proteins responsible for the cold hardening process in distinct plant tissues. The mentioned changes have been monitored using two dimensional difference gel electrophoresis (2D-DIGE) with subsequent peptide-mapping protein identification. Regarding approximately 600–700 distinct protein spots detected on 2D gels, there has been found at least a two-fold change after exposure to low temperatures in about 10% of proteins in leaves and 13% of proteins in crowns. Protein and nitrogen metabolic processes have been influenced by low temperature to a similar extent in both tissues while catabolism, carbohydrate metabolism and proteins involved in stress response have been more affected in crowns than in leaves. The range of changes in protein abundance was generally higher in leaves and chloroplast proteins were frequently affected which suggests a priority to protect photosynthetic apparatus. Overall, our data proved existence of slightly different response strategies to low temperature stress in crowns and leaves, i.e., tissues with different biological role. Moreover, there have been found several proteins with large increase in accumulation, e.g., 33 kDa oxygen evolving protein of photosystem II in leaves and “enhanced disease susceptibility 1” in crowns; these proteins might have potential to indicate an enhanced level of frost tolerance in barley.

Hlavackova, Iva; Vitamvas, Pavel; Santrucek, Jiri; Kosova, Klara; Zelenkova, Sylva; Prasil, Ilja Tom; Ovesna, Jaroslava; Hynek, Radovan; Kodicek, Milan

2013-01-01

23

Rapid Solution Hardening, Dislocation Mobility, and the Flow Stress of Crystals  

Microsoft Academic Search

A theory is derived for impurity-controlled dislocation mobility and the resultant temperature variation of the flow stress of lithium fluoride. The theory is suitable to crystals in which the hardening is primarily due to tetragonal lattice distortions such as result from the introduction of magnesium into lithium fluoride, these being defects whose interactions with dislocations have been calculated previously. Dislocation

Robert L. Fleischer

1962-01-01

24

YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS  

SciTech Connect

A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

Yin, Hebi [ORNL; Sabau, Adrian S [ORNL; Ludtka, Gerard Michael [ORNL; Skszek, Timothy [Vehma International of American, Inc.; Niu, X [Magna Cosma International, Promatek Research Centre

2013-01-01

25

Cloning and expression of five heat shock protein genes in relation to cold hardening and development in the leafminer, Liriomyza sativa.  

PubMed

The vegetable leafminer, Liriomyza sativae has spread worldwide, causing serious loss of agricultural productivity. Heat shock proteins (HSPs) play important roles in the environmental adaptation of various organisms, and to explore the functions of HSPs in relation to cold tolerance and development in L. sativae, three full-length cDNAs of small heat shock protein genes (ls-hsp19.5, ls-hsp20.8 and ls-hsp21.7) and two partial cDNAs of tcp1 (the hsp60 homolog, ls-tcp1alpha and ls-tcp1zeta) were cloned, and their transcriptional expression during cold hardening and development was examined by real time quantitative PCR. The open reading frames (ORFs) of ls-hsp19.5, ls-hsp20.8 and ls-hsp21.7 are 516, 543 and 573bp in length, encoding proteins with molecular weights (M.W.) of 19.5, 20.8 and 21.7kDa, respectively. The 956 and 323bp partial cDNAs were respectively sequenced from ls-tcp1alpha and ls-tcp1zeta. The expression profiles during cold hardening revealed that ls-tcp1s did not respond to cold stress. However, the three small hsps were significantly induced by cold, and ls-hsp20.8 was more cold-sensitive than the others. These results suggest that different shsp members may be responsible for cold stresses of different intensity. The expression of hsps during developmental processes revealed that the mRNA levels of small hsps reached a peak in the pupal stage, whereas the levels of large hsps, including two ls-tcp1s, hsp60 and hsp90 increased gradually with the developmental process. These results suggest that, in addition to a heat shock response, these HSPs may be involved in the development of L. sativae. PMID:19133268

Huang, Li-Hua; Wang, Chen-Zhu; Kang, Le

2009-03-01

26

Combined electron-spin-resonance, X-ray-diffraction studies on phospholipid vesicles obtained from cold-hardened wheats : II. The role of free sterols.  

PubMed

The contents of free sterols and phospholipids in leaves of wheat, Triticum aestivum L., cultivars of different frost resistances, as well as the physical state of isolated phospholipids in the presence and absence of sterols, were compared before and after hardening. There was an inverse relationship between the sterol/phospholipid ratio and frost tolerance as a consequence of both a decrease in the free sterol, and an increase in the total phospholipid content. Sterol-sterol interactions were investigated using wide angle X-ray diffraction, while the phase behaviour of phospholipid vesicles was studied using the electron-spin-resonance (ESR) technique. No sterol-sterol interactions at-10° C were detected in vesicles obtained from the hardened most cold-tolerant cultivar (Miranovskaja 808), containing sterols in a ratio (0.08) found in the original lipid extracts. In contrast, when the sterol-phospholipid ratio in the vesicles was set to the level (0.39) found in the extracts of the most sensitive cultivar, Penjamo 62, the appearance of sharp reflexion rings at 4.5ˇ10(-1), 4.8ˇ10(-1) and 5.0ˇ10(-1) nm indicated strong sterol-sterol interactions. The temperatures for the onset of phase separation for vesicles of identical sterol/phospholipid ratios found in lipid extracts of hardened Miranovskaja 808 were almost the same as those measured in purified phospholipids (-15 vs.-16° C). In contrast, the temperature for the onset of phase separation of vesicles with a sterol/phospholipid ratio characteristic of hardened Penjamo 62 was shifted upwards (from-6 to-2° C). Phase separation was not completed in the vesicles of Miranovskaja 808 in the temperature range scanned (-30° C) but was shifted from-22 to-18° C in the presence of sterols in the case of Penjamo 62. The results are discussed in terms of the composition and physical state of membranes in relation to survival at freezing temperatures. PMID:24232837

Horváth, I; Vigh, L; Woltjes, J; Farkas, T; van Hasselt, P; Kuiper, P J

1987-01-01

27

Corrosion behavior of rapidly solidified, precipitation-hardening stainless steels with B and Ti Additions  

Microsoft Academic Search

The excellent corrosion resistance of metallic glass alloys has been documented, but metallic glasses have limited commercial application. On the other hand, microscrystalline powders produced via rapid solidification technology (RST) can be consolidated easily into useful shapes using standard powder-metallurgy techniques. For this reason many investigators have studied the corrosion behavior of microcrystalline alloys produced via RST. The alloys that

T. A. Mozhi; R. Ray

1989-01-01

28

The effect of grain diameter and pre-cold work by torsion on the hardening behaviour of Ag-8 at.% Cu alloy  

NASA Astrophysics Data System (ADS)

Ag-8 at.% Cu wires of different grain diameters were cold-worked by twisting to different degrees than subjected to increased tensile loading at different working temperatures. The changes in work-hardening coefficient Xp were calculated. Pre-torsional deformation ? decreased Xp in fine grains (0.02 and 0.027 mm). In contrast, Xp was increased linearly by increasing ? in larger grains (0.07 and 0.12 mm). Increasing working temperature T causes a decrease in Xp. The rate ( ?Xp/ ??) = ? decreased by increasing T, and it has been found that the rate of decrease ??/ ?T is grain size dependent. The results were interpreted in terms of the dendritic structure of the alloy and mutual dislocation interactions.

Kenawy, M. A.; Saad, G.; Graiss, G.; Beshai, B.

1985-07-01

29

Causes and the methods of correction of the defects ``transverse ribbing'' and ``work-hardened bands'' on the surface of cold-rolled autobody sheets  

NASA Astrophysics Data System (ADS)

A surface defect in the form of parallel alternating dark and bright bands located across the rolling direction appear periodically upon cold rolling of thin-sheet steel intended for the face parts of cars. This defect is known as transverse ribbing and is visually observed upon rolling. The difference in the dark- and bright-band thicknesses can be determined with a micrometer. A similar but finer defect in the form of work-hardened bands has recently been detected. It is only observed after the sheet surface is processed with hones. In this case, the difference in the band thicknesses cannot be determined with a micrometer. A theory is proposed to explain the causes of the appearance of these defects, and methods for their correction are developed and tested on a commercial rolling mill.

Garber, E. A.; Pavlov, S. I.; Kuznetsov, V. V.; Timofeeva, M. A.; Traino, A. I.

2009-02-01

30

Magnetic hardening of the Pr 2Co 14B-based rapidly quenched alloys  

NASA Astrophysics Data System (ADS)

Pr 2Co 14B-based permanent magnets have been prepared by heat treatment of melt-spun ribbons. The ribbons were produced using the melt-spinning technique at linear speeds of the wheel higher than 35 m/s. The as-spun ribbons were found to be 'X-ray amorphous' with a near-zero intrinsic coercivity and saturation magnetization of 80-100 emu/g depending on the composition. Upon annealing at temperatures above 560°C, the intrinsic coercivity increases sharply reaching values higher than 15 kOe. At the same time the saturation magnetization decreases sharply. At high heat treatment temperatures (800-1000°C) the intrinsic coercivity drops slightly and the saturation magnetization increases largely. Thermomagnetic analysis (TMA) of the amorphous as-spun ribbons revealed that their Curie and crystallization temperatures are approximately 520 and 560°C, respectively. During crystallization from the amorphous state, the first phase to precipitate is Pr 2Co 14B followed by the PrCo 4B phase. At high temperatures a third phase appears which, depending on the alloy composition, can be the PrCo 5 or the PrCo 12B 6. The development of the magnetic properties following heat treatment at different temperatures can be interpreted in terms of the phases generated at each temperature. The tendency towards the formation of these phases can be interpreted in terms of the Pr-Co-B phase diagram. No PrCo 2 phase has been observed in the alloys. The maximum energy product of the isotropic Pr 2Co 14B-based permanent magnets is about 5 MGOe. The properties of Nd 2Co 14B-based rapidly quenched permanent magnets can be discussed in a way similar to the Pr 2Co 14B magnets. Their intrinsic coercivity and maximum energy product are about 10 kOe and 5.5 MgOe, respectively.

Christodoulou, C. N.; Massalski, T. B.; Wallace, W. E.

1993-07-01

31

A Comparative Spin-Label Study of Isolated Plasma Membranes and Plasma Membranes of Whole Cells and Protoplasts from Cold-Hardened and Nonhardened Winter Rye  

PubMed Central

Lipid-lipid and lipid-protein interactions in the plasma membranes of whole cells and protoplasts and an isolated plasma membrane fraction from winter rye (Secale cereale L. cv Puma) have been studied by spin labeling. Spectra were recorded between ?40°C and 40°C using the freely diffusing spin-label, 16-doxyl stearic acid, as a midbilayer membrane probe. The probe was reduced by the whole cells and protoplasts and reoxidized by external potassium ferricyanide. The reoxidized probe was assumed to be localized in the plasma membrane. The spectra consisted of the superposition of a narrow and a broad component indicating that both fluid and immobilized lipids were present in the plasma membrane. The two components were separated by digital subtraction of the immobilized component. Temperature profiles of the membranes were developed using the percentage of immobilized lipid present at each temperature and the separation between the outermost hyperfine lines for the fluid lipid component. Lipid immobilization was attributed to lipid-protein interactions, lipid-cell wall interactions, and temperature-induced lipid phase transitions to the gel-state. Temperature profiles were compared for both cold-hardened and nonhardened protoplasts, plasma membranes, and plasma membrane lipids, respectively. Although cold-hardening extended the range of lipid fluidity by 5°C, it had no effect on lipid-protein interactions or activation energies of lipid mobility. Differences were found, however, between the temperature profiles for the different samples, suggesting that alterations in the plasma membrane occurred as a consequence of the isolation methods used.

Windle, John J.

1988-01-01

32

Rapid remobilization of magmatic crystals kept in cold storage.  

PubMed

The processes involved in the formation and storage of magma within the Earth's upper crust are of fundamental importance to volcanology. Many volcanic eruptions, including some of the largest, result from the eruption of components stored for tens to hundreds of thousands of years before eruption. Although the physical conditions of magma storage and remobilization are of paramount importance for understanding volcanic processes, they remain relatively poorly known. Eruptions of crystal-rich magma are often suggested to require the mobilization of magma stored at near-solidus conditions; however, accumulation of significant eruptible magma volumes has also been argued to require extended storage of magma at higher temperatures. What has been lacking in this debate is clear observational evidence linking the thermal (and therefore physical) conditions within a magma reservoir to timescales of storage-that is, thermal histories. Here we present a method of constraining such thermal histories by combining timescales derived from uranium-series disequilibria, crystal sizes and trace-element zoning in crystals. At Mount Hood (Oregon, USA), only a small fraction of the total magma storage duration (at most 12 per cent and probably much less than 1 per cent) has been spent at temperatures above the critical crystallinity (40-50 per cent) at which magma is easily mobilized. Partial data sets for other volcanoes also suggest that similar conditions of magma storage are widespread and therefore that rapid mobilization of magmas stored at near-solidus temperatures is common. Magma storage at low temperatures indicates that, although thermobarometry calculations based on mineral compositions may record the conditions of crystallization, they are unlikely to reflect the conditions of most of the time that the magma is stored. Our results also suggest that largely liquid magma bodies that can be imaged geophysically will be ephemeral features and therefore their detection could indicate imminent eruption. PMID:24531766

Cooper, Kari M; Kent, Adam J R

2014-02-27

33

Strain induced martensite formation and its effect on strain hardening behavior in the cold drawn 304 austenitic stainless steels  

Microsoft Academic Search

SIM in the present cold drawn austenitic stainless steels, AISI 304 and AISI 304\\/Cu, nucleates mainly at the intersections of the mechanical twins rather than ?-martensite. The present results are attributed to the suppression of the formation of ?-martensite due to the increase of stacking fault energy which arise from the heat generated during high speed drawing and, for AISI

Jeom-Yong Choi; Won Jin

1997-01-01

34

An in situ neutron diffraction study of magnetic hardening in Fe3B/Nd2Fe14B nanocomposite magnets induced by rapid thermal annealing  

NASA Astrophysics Data System (ADS)

Neutron diffraction patterns were acquired in situ from a melt-spun amorphous Fe74Nd5B18Cr3 alloy upon heating at constant rates of 1.7×10-2 and 1.3 K/s. The diffraction patterns revealed the following decomposition reaction with two different intermediate routes: amorphous-->Fe3B/Nd2Fe23B3 (at 1.7×10-2 K/s) or Fe3B/Nd2Fe14B (at 1.3 K/s)-->Fe/Fe2B/Nd1.1Fe4B4. This confirms that the changeover between the two ternary compounds in the metastable intermediate state is the direct cause of magnetic hardening induced by rapid heating. The effect of group IVA-VIA metals on the magnetic hardness of Fe77Nd5B18 was investigated and only the 3d transition-metal additives appeared to be effective in enhancing the coercivity. The heterogeneous nucleation of Nd2Fe14B on tetragonal-Fe3B precipitates promoted by the 3d transition-metal additives is proposed as a possible mechanism of magnetic hardening.

Suzuki, K.; Garitaonandia, J. S.; Shih, J. C.; Cuello, G. J.; Shoji, T.; Kato, A.; Tajima, S.

2009-04-01

35

The significance of a rapid cold hemagglutination test for detecting mycoplasma infections in children with asthma exacerbation  

Microsoft Academic Search

Background and Purpose: Mycoplasma pneumoniae infection is a frequent cause of community-acquired respiratory infections in children and adults. However, standardized, rapid, specific methods for its diagnosis are lacking. The relationship between M. pneumoniae infection and asthma exacerbation has been recently discussed in the literature. We investigated the accuracy of rapid detection of mycoplasma infection by cold hemagglutination test compared to

Ya-Ting Chang; Yao-Hsu Yang; Bor-Luen Chiang

36

Comparative Study of Hardening Mechanisms During Aging of a 304 Stainless Steel Containing ?'-Martensite  

NASA Astrophysics Data System (ADS)

Strain aging and hardening behaviors of a 304 stainless steel containing deformation-induced martensite were investigated by examining mechanical properties and microstructural evolution for different aging temperature and time. Introduced age hardening mechanisms of a cold rolled 304 stainless steel were the additional formation of ?'-martensite, hardening of ?'-martensite, and hardening of deformed austenite. The increased amount of ?'-martensite at an aging temperature of 450 °C confirmed the additional formation of ?'-martensite as a hardening mechanism in a cold rolled 304 stainless steel. Additionally, the increased hardness in both ?'-martensite and austenite phases with aging temperature proved that hardening of both ?'-martensite and austenite phases would be effective as hardening mechanisms in cold rolled and aged 304 stainless steels. The results suggested that among hardening mechanisms, hardening of an ?'-martensite phase, including the diffusion of interstitial solute carbon atoms to dislocations and the precipitation of fine carbide particles would become a major hardening mechanism during aging of cold rolled 304 stainless steels.

Jeong, S. W.; Kang, U. G.; Choi, J. Y.; Nam, W. J.

2012-09-01

37

Hairpin folding dynamics: the cold-denatured state is predisposed for rapid refolding.  

PubMed

Cold denaturation is a general phenomenon in globular proteins, and the associated cold-denatured states of proteins have important fundamental and practical significance. Here, we have characterized the cold-denatured state of a beta-hairpin forming peptide, MrH3a, in 8% hexafluoro-2-propanol (HFIP) and the dynamics of its refolding following a laser-induced T-jump. Beta-hairpins constitute an important class of protein structural elements, yet their folding mechanisms are not fully understood. Characterization of MrH3a using NMR, CD, and IR spectroscopies reveals residual structure in the cold-denatured state, in contrast with the highly disordered heat-denatured state. The residual structure in the cold-denatured state comprises relatively compact and solvent protected conformations. Furthermore, we find a substantial acceleration in the rate of folding from the cold-denatured state compared to that of the heat-denatured state. In addition, the cold-denatured state is not populated in 20% HFIP; folding occurs only from the fully unfolded state and is significantly slower. We interpret the acceleration of the folding rate of MrH3a in 8% HFIP as a direct consequence of the collapsed conformations of the cold-denatured state. Finally, there may be some reduction of the loop search cost when starting from the cold-denatured state, since this state may have some of the stabilizing cross-strand interactions already formed. PMID:16042418

Dyer, R Brian; Maness, Shelia J; Franzen, Stefan; Fesinmeyer, R Matthew; Olsen, Katherine A; Andersen, Niels H

2005-08-01

38

Surface Fatigue Resistance with Induction Hardening  

NASA Technical Reports Server (NTRS)

Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

Townsend, Dennis; Turza, Alan; Chapman, Mike

1996-01-01

39

Cold acclimation induces rapid and dynamic changes in freeze tolerance mechanisms in the cryophile Deschampsia antarctica E. Desv.  

PubMed

The cryophilic Antarctic hair grass, Deschampsia antarctica E. Desv., one of two higher plants indigenous to Antarctica, represents a unique resource for the study of freeze tolerance mechanisms. We have previously characterized a multi-gene family in D. antarctica encoding ice recrystallization inhibition proteins (IRIPs) whose transcript levels are responsive to cold acclimation, and whose products confer ice recrystallization inhibition (RI) activity that can account for activity seen in cold acclimated plants. We used molecular and physiological analyses to investigate temporal responses of D. antarctica to cold acclimation and de-acclimation, and sub-zero acclimation. Quantitative profiling revealed that IRIP transcript levels significantly increased and decreased within hours of cold acclimation and de-acclimation, respectively, becoming up to 1000-fold more abundant in fully acclimated plants. Western analysis detected three major immuno-reactive bands whose pattern of accumulation mirrored that of transcript. These data correlated with the onset and decline of RI activity in acclimated and de-acclimated leaves. Plant survival-based testing revealed that cold acclimation enhanced freeze tolerance by 5 °C within 4 d, and that sub-zero acclimation conferred an additional 3 °C of tolerance. Thus, D. antarctica is highly responsive to temperature fluctuations, able to rapidly deploy IRIP based RI activity and enhance its freeze tolerance. PMID:22070607

Chew, Orinda; Lelean, Suzanne; John, Ulrik P; Spangenberg, German C

2012-04-01

40

Stress State of 12% Ni Maraging Steel After a Modified Procedure of Precipitation Hardening  

Microsoft Academic Search

Fatigue resistance of a surface layer of dynamically and thermomechanically loaded machine components and tool parts can be improved with a combination of mechanical hardening by cold deformation and thermal precipitation hardening. One of the mechanical processes of surface hardening is a relatively simple and accessible process of roto peening. The hardening effect of roto peening is related to a

J. Grum; M. Zupan?i?

2009-01-01

41

PRECIPITATION HARDENING P\\/M STAINLESS STEELS  

Microsoft Academic Search

Applications requiring high strength stainless steels are growing rapidally. Precipitation- hardening stainless steels have seen limited use in powder metallurgy despite their high strength. Strengthening of these alloys is achieved by adding elements such as copper and niobium, which form intermetallic precipitates during aging. The precipitation-hardening grades exhibit corrosion resistance levels comparable with those of the chromium-nickel (300 series) grades.

Chris Schade; Pat Stears; Alan Lawley; Roger Doherty

42

Surface segregation during rapid annealing of a cold rolled low carbon steel  

Microsoft Academic Search

Segregation conditions for industrial annealings are generally far from the laboratory ones as regards number, concentration, distribution of impurities and thermodynamical equilibrium of the material. Continuous annealing of steel sheets is a special case with regard to segregation for three main reasons: rolled sheets before annealing are heavily cold worked, the applied thermal cycle is very brief and the thermal

R. Cheron; X. Quillard; J. M. Roland; D. Roptin

1994-01-01

43

Hydraulic Signals from the Roots and Rapid Cell-Wall Hardening in Growing Maize (Zea mays L.) Leaves Are Primary Responses to Polyethylene Glycol-Induced Water Deficits.  

PubMed Central

We investigated mechanisms involved in inhibition of maize (Zea mays L.) leaf-elongation growth following addition of non-penetrating osmolyte to the root medium. The elongation rate of the first true leaf remained inhibited for 4 h after addition of polyethylene glycol 6000 (PEG; -0.5 MPa water potential), despite progressive osmotic adjustment in the growing leaf tissues. Thus, inhibition of leaf growth did not appear to be directly related to loss of leaf capacity to maintain osmotic potential gradients. Comparative cell-wall-extension capacities of immature (still expanding) leaf tissues were measured by creep extensiometry using whole plants. Reductions in irreversible (plastic) extension capacity (i.e. wall hardening) were detected minutes and hours after addition of PEG to the roots, by both in vivo and in vitro assay. The onset of the wall-hardening response could be detected by in vitro assay only 2 min after addition of PEG. Thus, initiation of wall hardening appeared to precede transcription-regulated responses. The inhibition of both leaf growth and wall-extension capacity was reversed by removal of PEG after 4 h. Moreover, wall hardening could be induced by other osmolytes (mannitol, NaCl). Thus, the leaf responses did not appear to be related to any specific (toxic) effect of PEG. We conclude that hardening of leaf cell walls is a primary event in the chain of growth regulatory responses to PEG-induced water deficits in maize. The signaling processes by which PEG, which is not expected to penetrate root cell walls or membranes, might cause cell-wall hardening in relatively distant leaves was also investigated. Plants with live or killed roots were exposed to PEG. The killed roots were presumed to be unable to produce hormonal or electrical signals in response to addition of PEG; however, inhibition of leaf elongation and hardening of leaf cell walls were detected with both live and killed roots. Thus, neither hormonal signaling nor signaling via induced changes in surface electrical potential were necessary, and hydraulic signals appeared to generate the leaf responses.

Chazen, O.; Neumann, P. M.

1994-01-01

44

[Rapid identification 15 effective components of anti common cold medicine with MRM by LC-MS/MS].  

PubMed

This paper reports the establishment of a method for rapid identification 15 effective components of anti common cold medicine (paracetamol, aminophenazone, pseudoephedrine hydrochloride, methylephedrine hydrochloride, caffeine, amantadine hydrochloride, phenazone, guaifenesin, chlorphenamine maleate, dextromethorphen hydrobromide, diphenhydramine hydrochloride, promethazine hydrochloride, propyphenazone, benorilate and diclofenac sodium) with MRM by LC-MS/MS. The samples were extracted by methanol and were separated from a Altantis T3 column within 15 min with a gradient of acetonitrile-ammonium acetate (containing 0.25% glacial acetic acid), a tandem quadrupole mass spectrometer equipped with electrospray ionization source (ESI) was used in positive ion mode, and multiple reaction monitoring (MRM) was performed for qualitative analysis of these compounds. The minimum detectable quantity were 0.33-2.5 microg x kg(-1) of the 15 compounds. The method is simple, accurate and with good reproducibility for rapid identification many components in the same chromatographic condition, and provides a reference for qualitative analysis illegally added chemicals in anti common cold medicine. PMID:23600148

Jiang, Jian-Guo; Zhang, Xi-Ru; Zhang, Yi-Hua; Song, Geng-Shen

2013-01-01

45

Rapid real-time detection of cold atoms with minimal destruction  

SciTech Connect

We present a minimally destructive interferometric measurement of the column density of cold atoms with a passively stabilized separated beam path interferometer. We achieve a heating rate of 4 (photons/sec)/atom. The interferometer employed in these measurements utilizes a photodiode rather than a charge-coupled device camera and is suitable for the measurement of fast dynamics in Bose-Einstein condensates and real-time feedback with atom lasers. The technique is compatible with modulation techniques employing squeezed light as the probe beam for sub-shot-noise-limited measurements.

Lye, J.E.; Hope, J.J.; Close, J.D. [Australian Centre for Quantum Atom Optics, Department of Physics, Australian National University, Australian Capital Territory 0200 (Australia)

2004-02-01

46

Rapid determination of immunoglobulin G concentration in cold ethanol precipitation process of raw plasma with near-infrared spectroscopy.  

PubMed

Near-infrared spectroscopy (NIRS) is known to be a powerful analytical tool in process monitoring. The feasibility of NIRS was investigated for determination of immunoglobulin G (IgG) in raw plasma cold ethanol precipitation process. Partial least squares (PLS) was used to develop regression model for 63 samples between spectra and reference data measured with a UV spectrophotometer. Three different variable selection methods, including correlation coefficient method, interval partial least squares (iPLS) and successive projection algorithm (SPA), were performed and compared with models based on all the variables. The values of Rc and root mean square error of cross validation (RMSECV) produced by the best model for the calibration set were 0.9599 and 0.6135 g/L, respectively. While for the validation set, the values of Rp and root mean square error of prediction (RMSEP) were 0.9577 and 0.4913 g/L, respectively. The results of this paper demonstrated that NIRS could be a feasible alternative approach for rapid determination of IgG in the cold ethanol precipitation process and can be used as a PAT tool in the future. PMID:23973581

Zhang, Hui; Liu, Aihua; Zang, Hengchang; Li, Hu; Jiang, Wei; Li, Lian; Wang, Jinfeng

2013-12-01

47

Rapid determination of immunoglobulin G concentration in cold ethanol precipitation process of raw plasma with near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Near-infrared spectroscopy (NIRS) is known to be a powerful analytical tool in process monitoring. The feasibility of NIRS was investigated for determination of immunoglobulin G (IgG) in raw plasma cold ethanol precipitation process. Partial least squares (PLS) was used to develop regression model for 63 samples between spectra and reference data measured with a UV spectrophotometer. Three different variable selection methods, including correlation coefficient method, interval partial least squares (iPLS) and successive projection algorithm (SPA), were performed and compared with models based on all the variables. The values of Rc and root mean square error of cross validation (RMSECV) produced by the best model for the calibration set were 0.9599 and 0.6135 g/L, respectively. While for the validation set, the values of Rp and root mean square error of prediction (RMSEP) were 0.9577 and 0.4913 g/L, respectively. The results of this paper demonstrated that NIRS could be a feasible alternative approach for rapid determination of IgG in the cold ethanol precipitation process and can be used as a PAT tool in the future.

Zhang, Hui; Liu, Aihua; Zang, Hengchang; Li, Hu; Jiang, Wei; Li, Lian; Wang, Jinfeng

2013-12-01

48

RAPID  

Cancer.gov

Rapid Access to Preventive Intervention Development (RAPID) Program About RAPID Description and Objectives of the Program Oversight RAPID Is Not... Frequently Asked Questions Application Information Format of Applications Address for Applications

49

Characterization of the Work Hardening Structure of Austenitic Steels by X-Ray Diffraction. Application to the Determination of Work Hardening Gradients and the Study of Recovery.  

National Technical Information Service (NTIS)

A method has been developed to determine quantitatively the work hardening of austenitic steels by measurement of the broadening of X-ray diffraction lines. This simple, rapid, accurate and sensible method enables to determine work hardening variations in...

R. Cadalbert J. L. Baron

1977-01-01

50

Rapid Quench Cold-Seal Apparatus with Computer-Controlled Pressure and Temperature Cycling  

NASA Astrophysics Data System (ADS)

We have constructed two computer-controlled, rapid quench, hydrothermal apparatuses that are ideal for experimentation on volcanological, geothermal, and ore deposit research problems. The devices can achieve maximum pressures of about 2 kbar and temperatures to 1100C, have the ability for experiments to be quenched very rapidly in a water-cooled environment, and are interfaced with computers which can control any regimen of pressure and/or temperature cycling that may be desired, accomplished via Lab-View software and data acquisition and motion control boards from National Instruments. The rapid quench aspects of the design were developed originally by Dr. Phil Ihinger and have subsequently been adopted by many labs around the world; a good summary description of these aspects of the equipment, and the use of filler-rods for controlling redox conditions in such equipment, are provided by Matthews et al. (2004, Am. Mineral., 88: 701-707). Our design has fixed Rene 41 pressure vessels, furnaces that are raised and lowered by computer controlled pneumatic cylinders and water cooling systems that are controlled by computer operated solenoid valves. The novel feature of our design is the pressure generation and control systems. We coupled the seal-ends of commercially available (HIP) pressure generators to shop-built linear actuators consisting of nearly frictionless ball lead screws within thick walled stainless steel housings. These in turn are driven by NEMA size 23 stepper motors coupled to 100:1 gear reduction units. The actuators require 21 revolutions to achieve their full stroke of 12.7 cm which displaces about 10 cc of fluid. Operating the motors at the relatively low resolution of 800 steps per revolution leads to about 132,000 steps per cm of travel of the pressure-generating piston, providing exceptionally high precision and excellent pressure control. Instantaneous decompression can be achieved by simply opening a valve while motor-controlled decompression from 2 kbar to 1 bar can occur over time spans ranging from about one minute to months. This equipment will find immediate use in studies of decompression- induced magmatic vesiculation and crystallization in sub-volcanic and volcanic conduit environments and decompression-induced precipitation of fracture-filling ore and silicate minerals in crustal hydrothermal environments.

Johnston, A.; Senkovich, D.

2007-12-01

51

Case hardening of steel  

SciTech Connect

The first chapter lays the groundwork for an understanding by covering absorption and diffusion of carbon, and the application of equilibrium data. Gas carburizing methods are presented, followed by other gaseous case hardening methods. Then, liquid case-hardening methods are discussed. Vacuum carburizing and pack carburizing are treated in a separate chapter. The second half of the volume deals with specific topics in relation to case hardening. First, heat-treatment considerations are presented, including chapters on cleaning and handling of parts, heat treatment, and furnaces and furnace parts and fixtures used in case hardening. The next chapter presents information on instrumentation and control the first section discussing temperature measurement and the second dealing with instrumentation for controlling carbonaceous atmospheres. Testing inspection and quality control are covered in sections detailing inspection and quality control, hardness testing of case-hardened parts, and methods of measuring case depth. The final chapter is an atlas of microstructures and macrostructures of case hardened parts.

Not Available

1987-01-01

52

Calcium signaling mediates cold sensing in insect tissues.  

PubMed

The ability to rapidly respond to changes in temperature is a critical adaptation for insects and other ectotherms living in thermally variable environments. In a process called rapid cold hardening (RCH), insects significantly enhance cold tolerance following brief (i.e., minutes to hours) exposure to nonlethal chilling. Although the ecological relevance of RCH is well-established, the underlying physiological mechanisms that trigger RCH are poorly understood. RCH can be elicited in isolated tissues ex vivo, suggesting cold-sensing and downstream hardening pathways are governed by brain-independent signaling mechanisms. We previously provided preliminary evidence that calcium is involved in RCH, and here we firmly establish that calcium signaling mediates cold sensing in insect tissues. In tracheal cells of the freeze-tolerant goldenrod gall fly, Eurosta solidaginis, chilling to 0 °C evoked a 40% increase in intracellular calcium concentration as determined by live-cell confocal imaging. Downstream of calcium entry, RCH conditions significantly increased the activity of calcium/calmodulin-dependent protein kinase II (CaMKII) while reducing phosphorylation of the inhibitory Thr306 residue. Pharmacological inhibitors of calcium entry, calmodulin activation, and CaMKII activity all prevented ex vivo RCH in midgut and salivary gland tissues, indicating that calcium signaling is required for RCH to occur. Similar results were obtained for a freeze-intolerant species, adults of the flesh fly, Sarcophaga bullata, suggesting that calcium-mediated cold sensing is a general feature of insects. Our results imply that insect tissues use calcium signaling to instantly detect decreases in temperature and trigger downstream cold-hardening mechanisms. PMID:23671084

Teets, Nicholas M; Yi, Shu-Xia; Lee, Richard E; Denlinger, David L

2013-05-28

53

Case hardening of sandstone  

NASA Astrophysics Data System (ADS)

The case-hardened crust developed on the Aztec Sandstone in the Valley of Fire, Nevada, has been characterized by a variety of techniques, including electron microscopy and infrared spectroscopy. The case-hardened crust consists mainly of host rock, with a fine-grained cement and wind-deposited kaolinite. The cement is usually calcite, but in some cases the hydrated calcium borate, colemanite, was found to be the case-hardening cement.

Conca, James L.; Rossman, George R.

1982-10-01

54

[Hardening of dental instruments].  

PubMed

The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented. PMID:7300627

Gerasev, G P

1981-01-01

55

Plasma surface hardening of ASSAB 760 steel specimens with Taguchi optimisation of the processing parameters  

Microsoft Academic Search

Surface hardening of steel components is traditionally done either by oxy-fuel, induction or laser hardening. Plasma arc is a new hardening technique which makes use of a small controlled stream of ionised gas to heat the material to its austenitising temperature. The heat is conducted rapidly into the bulk of the specimen causing self-quenching to occur and the formation of

L. J Yang

2001-01-01

56

Large strain work hardening of aluminum alloys and the effect of mg in solid solution  

Microsoft Academic Search

The work-hardening behavior of a range of aluminum-magnesium alloys, from 0.5 to 4.55 wt pct Mg, is followed up to large strains\\u000a using compression testing and cold rolling. At large strains, stage IV, an unexpectedly low work-hardening rate of high-Mg\\u000a alloys is observed, and the work-hardening rate in stage IV is almost unaffected by the Mg content. A model for

Řyvind Ryen; Hans Ivar Laukli; Bjřrn Holmedal; Erik Nes

2006-01-01

57

Strain hardening of aluminium alloy 3004 in the deep drawing and ironing processes  

Microsoft Academic Search

The evolution of material hardening resulting from the canmaking operations on aluminium beverage cans has been investigated. Tensile tests in cup walls revealed that deep drawing induced softening in the hoop direction and hardening in the meridian direction. This anisotropy is retained in the ironing operation. Changes in strain path on a heavily cold-rolled material probably cause such a complex

J. COURBON; J. L. DUVAL

1993-01-01

58

42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN AND TEMPER THE NAILS; WEST TUBES IN FOREGRPUND AND DRAWBACK TUBE IN THE CENTER - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

59

Cold stress causes rapid but differential changes in properties of plasma membrane H(+)-ATPase of camelina and rapeseed.  

PubMed

Camelina (Camelina sativa) and rapeseed (Brassica napus) are well-established oil-seed crops with great promise also for biofuels. Both are cold-tolerant, and camelina is regarded to be especially appropriate for production on marginal lands. We examined physiological and biochemical alterations in both species during cold stress treatment for 3 days and subsequent recovery at the temperature of 25°C for 0, 0.25, 0.5, 1, 2, 6, and 24h, with particular emphasis on the post-translational regulation of the plasma membrane (PM) H(+)-ATPase (EC3.6.3.14). The activity and translation of the PM H(+)-ATPase, as well as 14-3-3 proteins, increased after 3 days of cold stress in both species but recovery under normal conditions proceeded differently. The increase in H(+)-ATPase activity was the most dramatic in camelina roots after recovery for 2h at 25°C, followed by decay to background levels within 24h. In rapeseed, the change in H(+)-ATPase activity during the recovery period was less pronounced. Furthermore, H(+)-pumping increased in both species after 15min recovery, but to twice the level in camelina roots compared to rapeseed. Protein gel blot analysis with phospho-threonine anti-bodies showed that an increase in phosphorylation levels paralleled the increase in H(+)-transport rate. Thus our results suggest that cold stress and recovery in camelina and rapeseed are associated with PM H(+)-fluxes that may be regulated by specific translational and post-translational modifications. PMID:23399403

Kim, Hyun-Sung; Oh, Jung-Min; Luan, Sheng; Carlson, John E; Ahn, Sung-Ju

2013-06-15

60

Steels for surface hardening  

Microsoft Academic Search

1.The considerable technical and economic advantages of surface hardening after high-frequency heating, giving better service performance, labor savings during manufacture, lower heat treating cost and also offering the possibility of complex automation of the production cycle, may be used to fullest extent only if for the components in question a steel is selected whose composition and properties are attuned to

K. Z. Shepelyakovskii

1959-01-01

61

Effect of shock-wave treatment on the structure and hardening of austenitic steels  

NASA Astrophysics Data System (ADS)

The structure and hardening of austenitic steels subjected to shock-wave treatment have been studied. This treatment is shown to form a structure whose cell size decreases with increasing pressure. The treatment-induced hardening of the steels can be estimated using the Hall-Petch relation. At the same degrees of residual deformation, shock-wave treatment results in a significantly higher degree of hardening of the austenitic steels as compared to cold rolling. The degree of hardening increases with decreasing stacking-fault energy in austenite.

Blinov, V. M.; Tchernogorova, O. P.; Drozdova, E. I.; Afanas'ev, I. A.

2006-03-01

62

Precipitation-hardening alloys  

SciTech Connect

Designers of stainless steel and nickel alloy products are routinely faced with making tradeoffs between the properties needed for manufacturing and those required for its end use. When such compromises begin to adversely impact cost or performance, precipitation hardening (PH) alloys may offer a solution. Despite their more complex metallurgy, PH alloys are not necessarily more costly than many nonage-hardenable alloys. In fact, performance may be substantially higher than such alloys, without a cost penalty. Although corrosion resistance is decreased (or possibly increased) during the aging cycle, it is only by a slight amount. This article takes a closer look at PH stainless steel and nickel alloys, and provides several examples of applications.

Brucker, R. [Ulbrich Stainless Steels and Special Metals, North Haven, CT (United States)

1995-12-01

63

RHOBOT: Radiation hardened robotics  

SciTech Connect

A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

64

Rapid (0.5°C\\/min) minimally invasive induction of hypothermia using cold perfluorochemical lung lavage in dogs  

Microsoft Academic Search

Objective: Demonstrate minimally invasive rapid body core and brain cooling in a large animal model. Design: Prospective controlled animal trial. Setting: Private research laboratory. Subjects: Adult dogs, anesthetized, mechanically ventilated. Interventions: Cyclic lung lavage with FC-75 perfluorochemical (PFC) was administered through a dual-lumen endotracheal system in the new technique of ‘gas\\/liquid ventilation’ (GLV). In Trial-I, lavage volume (V-lav) was 19

Steven B. Harris; Michael G. Darwin; Sandra R. Russell; Joan M. O'Farrell; Mike Fletcher; Brian Wowk

2001-01-01

65

Microstructural characterization of the aluminum alloy 6063 after work hardening treatments  

Microsoft Academic Search

The aluminum 6063 alloy possesses a great industrial interest, presenting characteristics that justify its frequent use, when\\u000a compared to the other aluminum alloys: the precipitation hardening and high cold work capacity. These alloys present high\\u000a ductility, that allows their use in operations with high deformation degrees, as the cold work.[1,2

I. M. Espósito; S. J. Buso; W. A. Monteiro

66

Combined transcriptomic and metabolomic approach uncovers molecular mechanisms of cold tolerance in a temperate flesh fly.  

PubMed

The ability to respond rapidly to changes in temperature is critical for insects and other ectotherms living in variable environments. In a physiological process termed rapid cold-hardening (RCH), exposure to nonlethal low temperature allows many insects to significantly increase their cold tolerance in a matter of minutes to hours. Additionally, there are rapid changes in gene expression and cell physiology during recovery from cold injury, and we hypothesize that RCH may modulate some of these processes during recovery. In this study, we used a combination of transcriptomics and metabolomics to examine the molecular mechanisms of RCH and cold shock recovery in the flesh fly, Sarcophaga bullata. Surprisingly, out of ?15,000 expressed sequence tags (ESTs) measured, no transcripts were upregulated during RCH, and likewise RCH had a minimal effect on the transcript signature during recovery from cold shock. However, during recovery from cold shock, we observed differential expression of ?1,400 ESTs, including a number of heat shock proteins, cytoskeletal components, and genes from several cell signaling pathways. In the metabolome, RCH had a slight yet significant effect on several metabolic pathways, while cold shock resulted in dramatic increases in gluconeogenesis, amino acid synthesis, and cryoprotective polyol synthesis. Several biochemical pathways showed congruence at both the transcript and metabolite levels, indicating that coordinated changes in gene expression and metabolism contribute to recovery from cold shock. Thus, while RCH had very minor effects on gene expression, recovery from cold shock elicits sweeping changes in gene expression and metabolism along numerous cell signaling and biochemical pathways. PMID:22735925

Teets, Nicholas M; Peyton, Justin T; Ragland, Gregory J; Colinet, Herve; Renault, David; Hahn, Daniel A; Denlinger, David L

2012-08-01

67

Multipurpose hardened spacecraft insulation  

NASA Technical Reports Server (NTRS)

A Multipurpose Hardened Spacecraft Multilayer Insulation (MLI) system was developed and implemented to meet diverse survivability and performance requirements. Within the definition and confines of a MLI assembly (blanket), the design: (1) provides environmental protection from natural and induced nuclear, thermal, and electromagnetic radiation; (2) provides adequate electrostatic discharge protection for a geosynchronous satellite; (3) provides adequate shielding to meet radiated emission needs; and (4) will survive ascent differential pressure loads between enclosed volume and space. The MLI design is described which meets these requirements and design evolution and verification is discussed. The application is for MLI blankets which closeout the area between the laser crosslink subsystem (LCS) equipment and the DSP spacecraft cabin. Ancillary needs were implemented to ease installation at launch facility and to survive ascent acoustic and vibration loads. Directional venting accommodations were also incorporated to avoid contamination of LCS telescope, spacecraft sensors, and second surface mirrors (SSMs).

Steimer, Carlos H.

1990-01-01

68

Cold Sores  

MedlinePLUS

... directly to your desktop! more... What Are Cold Sores? Article Chapters What Are Cold Sores? Cold Sore ... 2012 Previous Next Related Articles: Canker and Cold Sores Aloe Vera May Help Relieve Mouth Sores Canker ...

69

Combined electron-spin-resonance, X-ray-diffraction studies on phospholipid vesicles obtained from cold-hardened wheats : I. An attempt to correlate electron-spin-resonance spectral characteristics with frost resistance.  

PubMed

Phospholipid multibilayers, obtained from two cultivars of thermally acclimated wheats of different frost resistances (Triticum aestivum L. cv. Penjamo 62, the sensitive cultivar, and T. aestivum L. cv. Miranovskaja 808, the frost-resistant cultivar), were investigated using electron-spin-resonance and X-ray-diffraction techniques. The former technique revealed two breaks in the motion of the spin-labelled fatty acid 2-(14-carboxyte-tradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl, for both cultivars (+3°C,-17° C and +5° C,-18° C, respectively) when grown at 22° C. The resistant cultivar compensated for exposure to cold (+2° C) by shifting the onset of the apparent phase-separation temperature from +3° C to-16° C. The sensitive cultivar was unable to do so. X-ray diffraction did not reveal fluid-to-gel transitions between +20° C and-10° C in any of the samples. The possible role of the formation of relatively ordered aggregates or clusters of lipid molecules discerned by spin probe within the otherwise freely dispersed liquid-like lipids is discussed in terms of freezing injury of plants. PMID:24232836

Vigh, L; Horváth, I; Woltjes, J; Farkas, T; van Hassett, P; Kuiper, P J

1987-01-01

70

Comparison of plane-strain and tensile work hardening in two sheet steel alloys  

Microsoft Academic Search

Extended tensile tests and newly-devised plane-strain tests have been performed on two commercial sheet steels: an aluminum-killed (A-K) steel and a cold-rolled, dual-phase (D-P) steel. Up to uniform strain in uniaxial tension, the average work-hardening rate of both steels was found to be independent of strain state (isotropic hardening). The planestrain behavior of both steels was in good agreement with

R. H. Wagoner

1981-01-01

71

Abnormal strain hardening in nanostructured titanium at high strain rates and large strains  

Microsoft Academic Search

Commercial purity nanostructured titanium prepared by equal channel angular pressing plus cold rolling (grain size ?260 nm)\\u000a exhibits a nonnegligible strain hardening behavior at large compressive strains (>15%) and quasistatic loading conditions.\\u000a The degree of the strain hardening increases with increasing strain rates and becomes more pronounced at dynamic loading rates.\\u000a This behavior is in contrast with what we have seen

Y. M. Wang; J. Y. Huang; T. Jiao; Y. T. Zhu; A. V. Hamza

2007-01-01

72

Ontogenetic variation in cold tolerance plasticity in Drosophila: is the Bogert effect bogus?  

NASA Astrophysics Data System (ADS)

Ontogenetic variation in plasticity is important to understanding mechanisms and patterns of thermal tolerance variation. The Bogert effect postulates that, to compensate for their inability to behaviourally thermoregulate, less-mobile life stages of ectotherms are expected to show greater plasticity of thermal tolerance than more-mobile life stages. We test this general prediction by comparing plasticity of thermal tolerance (rapid cold-hardening, RCH) between mobile adults and less-mobile larvae of 16 Drosophila species. We find an RCH response in adults of 13 species but only in larvae of four species. Thus, the Bogert effect is not as widespread as expected.

Mitchell, Katherine A.; Sinclair, Brent J.; Terblanche, John S.

2013-03-01

73

Single event upset hardening techniques  

SciTech Connect

Integrated circuit logic states are maintained by virtue of specific transistor combinations being either on'' (conducting) or off'' (nonconducting). High energy ion strikes on the microcircuit generate photocurrents whose primary detrimental effect is to make off'' transistors appear on,'' confusing the logic state and leading to single event upset (SEU). Protection against these soft errors is accomplished using either technology or circuit techniques, actions that generally impact yield and performance relative to unhardened circuits. We describe, and using circuit simulations analyze, a technique for hardening latches which requires combinations of technology and circuit modifications, but which provides SEU immunity without loss of speed. Specifically, a single logic state is hardened against SEU using technology methods and the information concerning valid states is then used to simplify hardened circuit design. The technique emphasizes some basic hardening concepts, ideas for which will be reviewed. 3 refs., 2 figs.

Weaver, H.T.; Corbett, W.T.

1990-01-01

74

Hardened Aircraft Shelter Test Program.  

National Technical Information Service (NTIS)

Operation DISTANT RUNNER produced data on the size and distribution of both airblast and debris produced by the detonation of 4500 kilograms of high explosive inside a Third Generation Hardened Aircraft Shelter. DISTANT RUNNER also produced data on the fr...

J. M. Swisdak

1992-01-01

75

Hardened Aircraft Shelter Test Program.  

National Technical Information Service (NTIS)

Operation DISTANT RUNNER produced data on the size and distribution of both airblast and debris produced by the detonation of 4500 kilograms of high explosive inside a Third Generation Hardened Aircraft Shelter. DISTANT RUNICER also produced data on the f...

M. M. Swisdak

1991-01-01

76

Solid Solution Softening and Hardening.  

National Technical Information Service (NTIS)

The note has been written to emphasize the experimental facts on which models of solid solution softening and hardening must be based in order to be meaningful. Specific discussion is made of tantalum and niobium alloys.

R. Gibala T. E. Mitchell

1973-01-01

77

Fire vehicle hardening  

SciTech Connect

After attack, the wartime fire fighter faces a harsh environment in which he must operate to perform his mission. Debris, unexploded bombs, and munitions pose hazards that must be overcome. Without modification to the fire-fighting vehicles, there is little assurance that the fire fighter would even be able to reach the locations necessary for performing his mission. Adding armor to the vehicle to protect both the operator and the vehicle from these hazards is the proposed solution. Through a study performed by the BDM Corporation under a subcontract to Martin Marietta Energy Systems, Inc., the recommended types, thicknesses, and locations of material necessary to allow the P-19 crash-rescue fire vehicle to survive, with 95% probability, 100 random events using the NATO Standard Fragment Threat Criteria was determined. Using this information, a preliminary design for a prototype hardening kit for the P-19 was developed. In conjunction with this effort, a P-19 was modified by installing attachment points, and mock-up armor was fabricated and fitted to the vehicle to refine the design. The kit design consisted of (1) various mild steel panels that varied in thickness from 0.125 to 0.375 in., (2) Lexan panels for areas that had to be transparent, (3) flexible Kevlar 49 for areas requiring flexibility, and (4) foam-filled tires. The factors considered in the design were the effects on the vehicle, fragment-stopping ability, weight, cost, ability to fabricate, and ease of installation. 40 figs.

Horner, L.G.

1988-11-01

78

The Use of a Simple Enzyme Assay in 'Seed-Hardening' Studies  

ERIC Educational Resources Information Center

Describes a single technique for an enzyme assay of catalase. The method shows that vegetable seeds submitted to pre-sowing 'hardening' cycles of imbition and drying have greater catalase activity and more rapid germination than do the controls. (LS)

Ead, J.; Devonald, V. G.

1975-01-01

79

Microstructure and Properties of Ti and Ti+Nb Ultra-Low-Carbon Bake Hardened Steels  

Microsoft Academic Search

Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti+Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstructure and texture evolution, as well as the morphology, size and distribution of second phase precipitates during hot rolling, cold rolling and continuous annealing were also analyzed. The results showed that the size of NbC precipitates in Ti+Nb

Ji-ping CHEN; Yong-lin KANG; Ying-min HAO; Guang-ming LIU; Ai-ming XIONG

2009-01-01

80

Radiation Hardened Electronics for Extreme Environments.  

National Technical Information Service (NTIS)

The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to...

A. S. Keys M. D. Watson

2007-01-01

81

Dynamic Pressure Hardening of Irregular Shapes.  

National Technical Information Service (NTIS)

The strengthening and hardening effects of shock waves in metal alloys were investigated, and an explosive hardening production technique was developed. Specimens of AISI 1018, AISI 4335, AISI 4340, and AISI H-11 steels; 18% nickel maraging steel; AISI 30...

A. E. Doherty J. Mykkanen E. K. Henriksen

1966-01-01

82

Hardening process in ternary lead-antimony-tin alloys for battery grids  

NASA Astrophysics Data System (ADS)

It is known that lead-antimony alloys are very well hardened by continuous precipitation, whereas lead-tin alloys present a discontinuous precipitation with a weak hardening effect. In these binary alloys, there is precipitation of either antimony or tin. In ternary alloys, the compound SbSn can also precipitate. This study is focused on the type of precipitation, the nature and the morphology of the precipitated phases, and the intensity of hardening in ternary Pb?Sb?Sn alloys in relation to the composition of the alloys and the ternary diagram. To simulate the different processes of grid production, four states are studied, namely, as-cast product, rehomogenized, cold worked, cold worked and rehomogenized. The alloys contain up to 2.5 wt.% Sb and 2.5 wt.% Sn.

Hilger, J. P.

83

Optimal Control of Laser Hardening  

Microsoft Academic Search

We present a mathematical model for the laser surface hardening of steel. It consists of a nonlinear heat equation coupled with a system of five ordinary differential equations to describe the volume fractions of the occuring phases. Existence, regularity and stability results are discussed. Since the resulting hardness can be estimated by the volume fraction of martensite, we formulate the

Dietmar Hömberg

1997-01-01

84

LASER HARDENING OF TURBINE BLADES  

Microsoft Academic Search

This paper briefly describes our theoretical and experimental work on the laser heat treatment of the surfaces of martensitic stainless steel turbine blades. A hardened zone, very small in thickness compared to the blade, has been obtained without melting the substrate or reducing its hardness. A large spot with a high density power (as calculated by ad hoc thermal models)

A. Camoletto; G. Molino; S. Talentino

1991-01-01

85

Life on the Hardened Border  

ERIC Educational Resources Information Center

The many Coast Salish groups distributed on both sides of the United States-Canada border on the Pacific coast today face significant obstacles to cross the international border, and in some cases are denied passage or intimidated into not attempting to cross. The current situation regarding travel by Aboriginal people reflects the "hardening" of…

Miller, Bruce Granville

2012-01-01

86

Precipitation hardening in aluminum alloy 6022  

Microsoft Academic Search

Although the precipitation process in Al-Mg-Si alloys has been extensively studied, the understanding of the hardening process is still incomplete, since any change in composition, processing and aging practices, etc., could affect the precipitation hardening behavior. In this paper, hardness measurements, differential scanning calorimetry and transmission electron microscopy have been utilized to study the precipitation hardening behavior in aluminum alloy

W. F. Miao; D. E. Laughlin

1999-01-01

87

Hardened Layer and Bending Fatigue Strength of Induction Hardened Thermally Refined Steel Gears  

Microsoft Academic Search

This paper presents a study on effects of the pre-treatment and the heating time on the hardened layer and the bending fatigue strength of induction hardened gears. The measurement of hardened layer and the bending fatigue test of induction hardened gears made of thermally refined and as-rolled S35C and S45C steels were carried out, and then profiles of hardened layer

Kouitsu Miyachika; Hideaki Katanuma; Jun Iwanaga; Hidefumi Mada

2009-01-01

88

Synergistic effects of local strain-hardening and dissolved oxygen on stress corrosion cracking of 316NG weld heat-affected zones in simulated BWR environments  

NASA Astrophysics Data System (ADS)

Stress corrosion cracking growth during long-term test in high temperature water was monitored in two 316NG weld heat-affected zones representing highly hardened and medially hardened regions. Cracking near the weld fusion line exhibited both macroscopic bifurcation and extensive microscopic branching, which was faster than that in the medially hardened region where crack kinking was observed. There is an interaction between material hardening and dissolved oxygen on crack growth. The effect of a single overloading on crack growth in 316NG heat-affected zones is less significant than that in a cold worked 316NG stainless steel.

Lu, Zhanpeng; Shoji, Tetsuo; Xue, He; Meng, Fanjiang; Fu, Chaoyang; Takeda, Yoichi; Negishi, Koji

2012-04-01

89

[Optimal coefficient of overlap of light spots during laser hardening of medical instruments].  

PubMed

The optimum coefficient of light spot intercepts in the course of laser hardening medical instruments is determined for the case when there are no unirradiated sites on the surface under treatment. The increase in the light spot diameter during irradiation has been shown to be followed by more rapid expansion of the hardened area in comparison with the one of the tempered zone. PMID:7098803

Stepanova, G A; Pogibenko, A V; Gerasev, G P

1982-01-01

90

Laser transformation hardening of a high-purity iron-carbon-chromium alloy  

Microsoft Academic Search

Successful laser transformation hardening of steel surfaces requires that the absorbed laser energy is sufficient to austenitize the initial microstructure to a depth of 0.5 mm or more. Hardening is accomplished when rapid cooling by conduction of heat away from the surface causes transformation of the austenite layer to martensite. Heating and cooling rates of 10⁴ K\\/s or greater are

J. R. Bradley; S. Kim

1989-01-01

91

Method for determining the hardness of strain hardening articles of tungsten-nickel-iron alloy  

DOEpatents

The present invention is directed to a rapid nondestructive method for determining the extent of strain hardening in an article of tungsten-nickel-iron alloy. The method comprises saturating the article with a magnetic field from a permanent magnet, measuring the magnetic flux emanating from the article, comparing the measurements of the magnetic flux emanating from the article with measured magnetic fluxes from similarly shaped standards of the alloy with known amounts of strain hardening to determine the hardness.

Wallace, Steven A. (Knoxville, TN)

1984-01-01

92

Cluster hardening in an aged Al-Cu-Mg alloy  

SciTech Connect

The phenomenon of age hardening was first discovered in an Al-Cu-Mg alloy by Wilm in Berlin in 1906. Here the authors present a new interpretation of the origin of hardening in these important alloys. The first stage of hardening in Al-Cu-Mg alloys has generally been attributed to the formation of Guinier-Preston zones comprised of copper and magnesium atoms (often known as GPB zones), although the structure and chemistry of GPB zones remains poorly defined. Evidence for the existence of these zones and their characteristics is based on interpretations of weak diffraction effects arising from diffuse X-ray scattering in alloys aged for times corresponding to various stages along the hardness plateau. Bagaryatsky considered the zones to be associated with short range ordering along the {l_brace}100{r_brace}{alpha} planes. Evidence for the source of the rapid early hardening has therefore been sought by recourse to the technique of atom probe field ion microscopy (APFIM).

Ringer, S.P.; Polmear, I.J. [Monash Univ., Clayton, Victoria (Australia). Dept. of Materials Engineering] [Monash Univ., Clayton, Victoria (Australia). Dept. of Materials Engineering; Hono, Kazuhiro [National Research Inst. for Metals, Tsukuba (Japan)] [National Research Inst. for Metals, Tsukuba (Japan); Sakurai, Toshio [Tohoku Univ., Sendai (Japan). Inst. for Materials Research] [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

1997-03-01

93

Hardened Layer and Bending Fatigue Strength of Induction Hardened Thermally Refined Steel Gears  

NASA Astrophysics Data System (ADS)

This paper presents a study on effects of the pre-treatment and the heating time on the hardened layer and the bending fatigue strength of induction hardened gears. The measurement of hardened layer and the bending fatigue test of induction hardened gears made of thermally refined and as-rolled S35C and S45C steels were carried out, and then profiles of hardened layer and S-N curves were obtained. Effects of the pre-treatment and the heating time on profiles and micro structures of hardened layers of induction hardened gears were examined. The relationship between the bending fatigue strength and the profile of hardened layer was determined. An optimum heating condition for the bending fatigue strength of induction hardened S35C and S45C steel gears were indicated.

Miyachika, Kouitsu; Katanuma, Hideaki; Iwanaga, Jun; Mada, Hidefumi

94

Rapid stalk elongation in tulip (Tulipa gesneriana L. cv. Apeldoorn) and the combined action of cold-induced invertase and the water-channel protein gammaTIP.  

PubMed

Many bulbous plants need a low-temperature treatment for flowering. Cold, for example, affects the elongation of the stalk, thereby influencing the quality of the cut flower. How the elongation of the stalk is promoted by cold and which physiological and biochemical mechanisms are involved have remained obscure. As invertase has been shown to be involved in the cold-induced elongation of the flower stalks of tulips (Lambrechts et al., 1994, Plant Physiol 104: 515-520), we further characterized this enzyme by cloning the cDNA and analysing its expression in various tissues of the tulip (Tulipa gesneriana L. cv. Apeldoorn) stalk. In addition, the role of sucrose synthase was investigated. Since turgor pressure is an important force driving cell elongation, the role of a water-channel protein (gammaTIP) was studied in relation to these two enzymes. The mRNA level of the invertase found was substantially up-regulated as a result of cold treatment. Analysis of the amino acid sequence of this invertase revealed the presence of a vacuolar targeting signal. Two different forms of sucrose synthase were found, the expression of one of them appeared to be restricted to the vascular tissue while the other form was present in the surrounding tissue. Both sucrose synthases were present in the stalk during the entire period of bulb storage and after planting, but their activities declined during stalk elongation. The expression of the gammaTIP gene was restricted mainly to the vascular tissue and its expression profile was identical to that of invertase. Simultaneous expression of invertase and gammaTIP possibly leads to an increase in osmotic potential and vacuolar water uptake, thus providing a driving force for stretching the stalk cells. PMID:10502102

Balk, P A; de Boer, A D

1999-09-01

95

A review of the use of high power diode lasers in surface hardening  

Microsoft Academic Search

Laser surface hardening, although possible for a number of years, is a technology which is still in its infancy. The process involves the use of high intensity laser radiation to rapidly heat the surface of a steel into the austenitic region. Due to high rates of heat transfer, steep temperature gradients are set up which result in rapid cooling by

E. Kennedy; G. Byrne; D. N. Collins

2004-01-01

96

Can Winter-Active Bumblebees Survive the Cold? Assessing the Cold Tolerance of Bombus terrestris audax and the Effects of Pollen Feeding  

PubMed Central

There is now considerable evidence that climate change is disrupting the phenology of key pollinator species. The recently reported UK winter activity of the bumblebee Bombus terrestris brings a novel set of thermal challenges to bumblebee workers that would typically only be exposed to summer conditions. Here we assess the ability of workers to survive acute and chronic cold stress (via lower lethal temperatures and lower lethal times at 0°C), the capacity for rapid cold hardening (RCH) and the influence of diet (pollen versus nectar consumption) on supercooling points (SCP). Comparisons are made with chronic cold stress indices and SCPs in queen bumblebees. Results showed worker bees were able to survive acute temperatures likely to be experienced in a mild winter, with queens significantly more tolerant to chronic cold temperature stress. The first evidence of RCH in any Hymenoptera is shown. In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature. These results are discussed in the light of winter active bumblebees and climate change.

Owen, Emily L.; Bale, Jeffrey S.; Hayward, Scott A. L.

2013-01-01

97

Comparison of plane-strain and tensile work hardening in two sheet steel alloys  

Microsoft Academic Search

Extended tensile tests and newly-devised plane-strain tests have been performed on two commercial sheet steels: an aluminum-killed\\u000a (A-K) steel and a cold-rolled, dual-phase (D-P) steel. Up to uniform strain in uniaxial tension, the average work-hardening\\u000a rate of both steels was found to be independent of strain state (isotropic hardening). The planestrain behavior of both steels\\u000a was in good agreement with

R. H. Wagoner

1981-01-01

98

Cold-Nuclear-Matter Effects on Heavy-Quark Production at Forward and Backward Rapidity in d+Au Collisions at sqrt[s_{NN}]=200??GeV.  

PubMed

The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1rapidity (1.4<|y|<2.0) in d+Au and p+p collisions at sqrt[s_{NN}]=200??GeV. In central d+Au collisions, relative to the yield in p+p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p_{T} broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d+Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter. PMID:25014805

Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Bataineh, H; Al-Ta'ani, H; Alexander, J; Andrews, K R; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Aschenauer, E C; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Ben-Benjamin, J; Bennett, R; Bhom, J H; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Broxmeyer, D; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Caringi, A; Castera, P; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa Del Valle, Z; Connors, M; Csanád, M; Csörg?, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gal, C; Garishvili, I; Glenn, A; Gong, H; Gong, X; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Guo, L; Gustafsson, H-Ĺ; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Harper, C; Hashimoto, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; John, D; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kamin, J; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D J; Kim, E-J; Kim, Y-J; Kim, Y K; Kinney, E; Kiss, A; Kistenev, E; Kleinjan, D; Kline, P; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotov, D; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Li, X; Lichtenwalner, P; Liebing, P; Lim, S H; Linden Levy, L A; Liška, T; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malik, M D; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Milov, A; Mitchell, J T; Miyachi, Y; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, S K; Park, W J; Pate, S F; Patel, L; Pei, H; Peng, J-C; Pereira, H; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Ruži?ka, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sarsour, M; Sato, T; Savastio, M; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shim, H H; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slune?ka, M; Sodre, T; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Utsunomiya, K; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M

2014-06-27

99

Low-power laser hardening of steels  

Microsoft Academic Search

The results of a study of surface hardening of steels by low-power (100W) CO2 laser radiation are presented. Three-fold increase of surface microhardness of low- and medium-carbon steels was obtained. The depth of hardening zone was 170?m. A comparative analysis of laser hardening with the use of pulse (t=6ns, ?=532nm) radiation was made. The study shows that low-power CO2 lasers

R. A Ganeev

2002-01-01

100

Transmission and scanning electron microscope study on the secondary cyclic hardening behavior of interstitial-free steel  

SciTech Connect

Strain controlled fatigue experiment was employed to evaluate automotive grade interstitial-free ferrite steel. Hundreds of grains were examined by scanning electron microscope under electron channeling contrast image technique of backscattered electron image mode for comprehensive comparison of micrographs with those taken under transmission electron microscope. The cyclic stress responses clearly revealed that rapid hardening occurs at the early stage of cycling as a result of multiplication of dislocations to develop loop patches, dipolar walls and dislocation cells at various total strain amplitudes. After primary rapid hardening, stress responses varied from being saturated to further hardening according to dislocation structure evolution at various strain amplitudes. The fatigue failure was always accompanied with further hardening including secondary hardening. The corresponding dislocation structures with the three types of hardening behaviors are discussed. Once the secondary hardening starts, dislocation cells began to develop along grain boundaries in the low strain region and then extended into grain interiors as strain amplitudes increased and cycling went on. The secondary hardening rates were found to be directly proportional to their strain amplitudes.

Shih, Chia-Chang; Ho, New-Jin [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Huang, Hsing-Lu, E-mail: hlhuang8423@gmail.com [Department of Mechanical Engineering, Chinese Military Academy, Kaohsiung, Taiwan (China)

2009-11-15

101

Laser hardening of small-diameter shafts of secondarily hardening steels  

SciTech Connect

The purpose of this work was a study of the influence of heat treatment conditions of small diameter shafts of secondarily hardening steel on the hardened case depth in subsequent spiral surface laser hardening. Specimens with a diameter of 10 mm of Kh9VMFSh steel oil hardened from austenitizing temperatures of 980 and 1080/sup 0/C (60-61 HRC) were used. The study of the microstructure and measurements of the hardened case depth were made on polished specimens with a microscope. Microhardness across the depth of the hardened case was also measured. The laser heat treatment was done with a continuous CO/sub 2/ laser with a radiation power of 2 kW. The effective method for final heat treatment was determined to consist of oil hardening from austenitizing temperatures, surface laser hardening, and high-temperature tempering.

Babei, Yu.I.; Batashov, K.V.; Beletskii, V.V.; Berezhnitskaya, M.F.; Ivanov, S.A. Chervatyuk, V.A.

1988-01-01

102

Work Hardening and Annealing of Copper  

NSDL National Science Digital Library

This activity will demonstrate the process of work hardening and annealing of a copper. Students will get the opportunity to see the hardening of metal by deformation, experience the process of work hardening, explain the effects of work hardening in metals and experience property changes affected by annealing. This activity would be appropriate for grades 4 through high school and college level, with each age group gaining different educational benefits. Around 60 minutes is required for the demonstration. Student, instructor and course evaluation questions are included. This document will serve as a framework for instructors and may be downloaded in PDF format.

Stoebe, Thomas G.

2012-10-18

103

Radiation Hardened Electronics for Extreme Environments  

NASA Technical Reports Server (NTRS)

The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

Keys, Andrew S.; Watson, Michael D.

2007-01-01

104

210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef  

NASA Astrophysics Data System (ADS)

Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of corals from one of the world's largest known cold-water coral reef, the Rřst Reef off Norway. Two large branching framework-forming cold-water coral specimens, one Lophelia pertusa and one Madrepora oculata were collected alive at 350 m water depth from the Rřst Reef at ~67° N and ~9° E. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and the corals trace element compositions were studied using ICP-QMS. Due to the different chemical behaviors of Pb and Ra in the marine environment, 210Pb and 226Ra were not incorporated the same way into the aragonite skeleton of those two cold-water corals. Thus to assess of the growth rates of both specimens we have here taken in consideration the exponential decrease of initially incorporated 210Pb as well as the ingrowth of 210Pb from the decay of 226Ra. Moreover a~post-depositional 210Pb incorporation is found in relation to the Mn-Fe coatings that could not be entirely removed from the oldest parts of the skeletons. The 226Ra activities in both corals were fairly constant, then assuming constant uptake of 210Pb through time the 210Pb-226Ra chronology can be applied to calculate linear growth rate. The 45.5 cm long branch of M. oculata reveals an age of 31 yr and a~linear growth rate of 14.4 ą 1.1 mm yr-1, i.e. 2.6 polyps per year. However, a correction regarding a remaining post-depositional Mn-Fe oxide coating is needed for the base of the specimen. The corrected age tend to confirm the radiocarbon derived basal age of 40 yr (using 14C bomb peak) with a mean growth rate of 2 polyps yr-1. This rate is similar to the one obtained in Aquaria experiments under optimal growth conditions. For the 80 cm-long specimen of L. pertusa a remaining contamination of metal-oxides is observed for the middle and basal part of the coral skeleton, inhibiting similar accurate age and growth rate estimates. However, the youngest branch was free of Mn enrichment and this 15 cm section reveals a growth rate of 8 mm yr-1 (~1 polyp every two to three years). However, the 210Pb growth rate estimate is within the lowermost ranges of previous growth rate estimates and may thus reflect that the coral was not developing at optimal growth conditions. Overall, 210Pb-226Ra dating can be successfully applied to determine the age and growth rate of framework-forming cold-water corals, however, removal of post-depositional Mn-Fe oxide deposits is a prerequisite. If successful, large branching M. oculata and L. pertusa coral skeletons provide unique oceanographic archive for studies of intermediate water environmentals with an up to annual time resolution and spanning over many decades.

Sabatier, P.; Reyss, J.-L.; Hall-Spencer, J. M.; Colin, C.; Frank, N.; Tisnérat-Laborde, N.; Bordier, L.; Douville, E.

2011-12-01

105

Cosmic-ray Helium Hardening  

NASA Astrophysics Data System (ADS)

Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 1015eV, and (2) all CR spectra become hard at gsim1011eV nucleon-1. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at ~100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with ~106 K. Our model predicts hard and concave spectra for heavier CR elements.

Ohira, Yutaka; Ioka, Kunihito

2011-03-01

106

Cold Nuclear Matter Effects on J/? Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at sNN=200GeV  

NASA Astrophysics Data System (ADS)

We present measurements of J/? yields in d+Au collisions at sNN=200GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/? rapidity (-2.2rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bhom, J. H.; Bickley, A. A.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Caringi, A.; Chang, B. S.; Chang, W. C.; Charvet, J.-L.; Chen, C.-H.; Chernichenko, S.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Constantin, P.; Csanád, M.; Csörg?, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'Yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Ĺ.; Hadj Henni, A.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haruna, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, S. H.; Kim, Y.-J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Layton, D.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Lenzi, B.; Li, X.; Lichtenwalner, P.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; Means, N.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Niita, T.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ruži?ka, P.; Rykov, V. L.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Semenov, V.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.

2011-09-01

107

Laser hardening of ferritic malleable iron  

Microsoft Academic Search

To harden the surface of parts made of KCh 35-10 malleable iron operating at temperatures up to 300° one can recommend laser heat treatment. The use of laser hardening for differential gears at AZLK has produced savings of 303,000 rubles.

V. E. Arkhipov; A. N. Grechin; M. L. Khina

1980-01-01

108

Stage IV work hardening in cubic metals  

Microsoft Academic Search

The work hardening of fcc metals at large strains is discussed with reference to the linear stress-strain behavior often observed at large strains and known as Stage IV. The experimental evidence shows that Stage IV is a work hardening phenomenon that is found quite generally, even in pure fcc metals subjected to homogeneous deformation. A simple model for Stage IV

A. D. Rollett; U. F. Kocks; R. D. Doherty

1986-01-01

109

210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef  

NASA Astrophysics Data System (ADS)

Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of two corals from the world's largest known cold-water coral reef, Rřst Reef, north of the Arctic circle off Norway. Colonies of each of the two species that build the reef, Lophelia pertusa and Madrepora oculata, were collected alive at 350 m depth using a submersible. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and trace element compositions were studied. 210Pb and 226Ra differ in the way they are incorporated into coral skeletons. Hence, to assess growth rates, we considered the exponential decrease of initially incorporated 210Pb, as well as the increase in 210Pb from the decay of 226Ra and contamination with 210Pb associated with Mn-Fe coatings that we were unable to remove completely from the oldest parts of the skeletons. 226Ra activity was similar in both coral species, so, assuming constant uptake of 210Pb through time, we used the 210Pb-226Ra chronology to calculate growth rates. The 45.5 cm long branch of M. oculata was 31 yr with an average linear growth rate of 14.4 ą 1.1 mm yr-1 (2.6 polyps per year). Despite cleaning, a correction for Mn-Fe oxide contamination was required for the oldest part of the colony; this correction corroborated our radiocarbon date of 40 yr and a mean growth rate of 2 polyps yr-1. This rate is similar to the one obtained in aquarium experiments under optimal growth conditions. For the 80 cm-long L. pertusa colony, metal-oxide contamination remained in both the middle and basal part of the coral skeleton despite cleaning, inhibiting similar age and growth rate estimates. The youngest part of the colony was free of metal oxides and this 15 cm section had an estimated a growth rate of 8 mm yr-1, with high uncertainty (~1 polyp every two to three years). We are less certain of this 210Pb growth rate estimate which is within the lowermost ranges of previous growth rate estimates. We show that 210Pb-226Ra dating can be successfully applied to determine the age and growth rate of framework-forming cold-water corals if Mn-Fe oxide deposits can be removed. Where metal oxides can be removed, large M. oculata and L. pertusa skeletons provide archives for studies of intermediate water masses with an up to annual time resolution and spanning over many decades.

Sabatier, P.; Reyss, J.-L.; Hall-Spencer, J. M.; Colin, C.; Frank, N.; Tisnérat-Laborde, N.; Bordier, L.; Douville, E.

2012-03-01

110

Application of plastic anisotropy and non-isotropic hardening to springback prediction  

NASA Astrophysics Data System (ADS)

Springback is sensitive to the stress/moment distribution following a forming operation. To assess the sensitivity of springback to plastic hardening laws, special draw/bend tests were analyzed and compared to existing measurements. Systematic discrepancies were noted. Uniaxial tension-compression results were utilized to construct reverse hardening rules for three sheet materials: drawing-quality silicon-killed steel (DQSK), high-strength low-alloy steel (HSLA), and 6022-T4 aluminum alloy (6022-T4). A two-surface plasticity model was constructed, consisting of an active yield surface and a bounding surface. Initial yield was of the von Mises type. The active surface is of the Armstrong-Frederick type, with extra terms added to allow for the translation of the active yield to be influenced by the translation of the bounding surface (or limiting surface). To model the permanent softening observed in the tension-compression tests, the bounding surface was allowed to translate and expand according to a mixed hardening rule. This model effectively reproduces the two main features of the measured reverse hardening behavior of metal sheets: (1) low yield stress and rapid initial work hardening, and (2) persistent offset of long-strain hardening relative to isotropic hardening. Application of the new hardening model to simulations of springback with the draw/bend test improves the quality of agreement by a factor of two, compared to the results from the conventional isotropic hardening model. The hardening model is further extended to incorporate several forms of initial plastic anisotropy: Hill's quadric yield function, Barlat's three-parameter yield function, and Barlat's 1996 yield function. In addition to modeling the transient hardening and permanent softening of the uniaxial reverse loading curve, the new laws thus also take into account variations of R-value and yield stress with direction. These constitutive equations were implemented in ABAQUS via the UMAT option. Depending on the choice of yield function, the springback prediction of the draw/bend test for aluminum alloys is shown to improve, especially at lower back forces. The planar anisotropy has a strong influence on the loaded and unloaded anticlastic curvatures generated from the bending and unbending deformation in the draw/bend test. The combination of Barlat's 1996 yield function and the hardening model incorporating the Bauschinger effect give improved predictions of springback angles and anticlastic curvature.

Geng, Lumin

2000-10-01

111

Strain Hardening in Fractal Colloidal Gels  

NASA Astrophysics Data System (ADS)

Diffusion-limited aggregation of fractal clusters leads to arrested structures that have unusually high elastic moduli, characterized by an elastic modulus G'(?) which is nearly constant over a large range of frequencies 10-4 rad/srapidly, roughly as exp(?^2). We explain the observed strain hardening by considering affine deformations of a tree-like network of fractal clusters, leading to a spring constant for the extension of a backbone segment which increases with deformation. We find that the strain-dependent elastic modulus depends critically on the fractal dimension db of the backbone, the magnitude being determined by the characteristic cluster size. Our theory is found to be in good agreement with experimental data.

Gisler, Thomas; Weitz, David A.; Ball, Robin C.

1998-03-01

112

Centrality, rapidity, and transverse-momentum dependence of cold nuclear matter effects on J/psi production in dAu, CuCu, and AuAu collisions at sq root(s{sub NN})=200 GeV  

SciTech Connect

We have carried out a wide study of cold nuclear matter (CNM) effects on J/psi production in dAu, CuCu and AuAu collisions at sq root(s{sub NN})=200 GeV. We have studied the effects of three different gluon-shadowing parametrizations, using the usual simplified kinematics for which the momentum of the gluon recoiling against the J/psi is neglected as well as an exact kinematics for a 2->2 process; namely g+g->J/psi+g as expected from LO pQCD. We have shown that the rapidity distribution of the nuclear modification factor R{sub dAu}, and particularly its antishadowing peak, is systematically shifted toward larger rapidities in the 2->2 kinematics, irrespective of which shadowing parametrization is used. In turn, we have noted differences in the effective final-state nuclear absorption needed to fit the PHENIX dAu data. Taking advantage of our implementation of 2->2 kinematics, we have also computed the transverse momentum dependence of the nuclear modification factor, which cannot be predicted with the usual simplified kinematics. All the corresponding observables have been computed for CuCu and AuAu collisions and compared to the PHENIX and STAR data. Finally, we have extracted the effective nuclear absorption from the recent measurements of R{sub CP} in dAu collisions by the PHENIX collaboration.

Ferreiro, E. G. [Departamento de Fisica de Particulas, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Fleuret, F. [Laboratoire Leprince Ringuet, Ecole polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Lansberg, J. P. [Centre de Physique Theorique, Ecole polytechnique, CNRS, F-91128 Palaiseau (France); SLAC National Accelerator Laboratory, Theoretical Physics, Stanford University, Menlo Park, California 94025 (United States); Rakotozafindrabe, A. [IRFU/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France)

2010-06-15

113

Changes in ABA and gene expression in cold-acclimated sugar maple.  

PubMed

To determine if cold acclimation of sugar maple (Acer saccharum Marsh.) is associated with specific changes in gene expression under natural hardening conditions, we compared bud and root translatable mRNAs of potted maple seedlings after cold acclimation under natural conditions and following spring dehardening. Cold-hardened roots and buds were sampled in January when tissues reached their maximum hardiness. Freezing tolerance, expressed as the lethal temperature for 50% of the tissues (LT(50)), was estimated at -17 degrees C for roots, and at lower than -36 degrees C for buds. Approximately ten transcripts were specifically synthesized in cold-acclimated buds, or were more abundant in cold-acclimated buds than in unhardened buds. Cold hardening was also associated with changes in translation. At least five translation products were more abundant in cold-acclimated buds and roots compared with unhardened tissues. Abscisic acid (ABA) concentration increased approximately tenfold in the xylem sap following winter acclimation, and the maximum concentration was reached just before maximal acclimation. We discuss the potential involvement of ABA in the observed modification of gene expression during cold hardening. PMID:14759911

Bertrand, A; Robitaille, G; Castonguay, Y; Nadeau, P; Boutin, R

1997-01-01

114

Influence of laser surface hardening on the corrosion resistance of martensitic stainless steel  

Microsoft Academic Search

Martensitic high nitrogen stainless steels offer a combination of wear-, corrosion- and fatigue properties. But for some applications a higher surface hardness is required. A laser hardening with rapid heating (without smelting) and cooling (quenching) rates can improve the surface hardness with compressive residual stresses in the near surface layer. Yet, some cases of pitting corrosion in chloride media are

Y. Van Ingelgem; I. Vandendael; D. Van den Broek; A. Hubin; J. Vereecken

2007-01-01

115

Mechanism of minimum quantity lubrication in high-speed milling of hardened steel  

Microsoft Academic Search

The rapid wear rate of cutting tools due to high cutting temperature is a critical problem to be solved in high-speed machining (HSM) of hardened steels. Near-dry machining such as minimum quantity lubrication (MQL) is regarded as one of the solutions to this difficulty. However, the function of MQL in HSM is still uncertain so far which prevents MQL from

Y. S. Liao; H. M. Lin

2007-01-01

116

Identification of a receptor-like protein kinase gene rapidly induced by abscisic acid, dehydration, high salt, and cold treatments in Arabidopsis thaliana.  

PubMed Central

A cDNA clone for a receptor-like protein kinase gene (RPK1) was isolated from Arabidopsis thaliana. The clone is 1952 bp long with 1623 bp of an open reading frame encoding a peptide of 540 amino acids. The deduced peptide (RPK1) contains four distinctive domains characteristic of receptor kinases: (a) a putative amino-terminal signal sequence domain; (b) a domain with five extracellular leucine-rich repeat sequences; (c) a membrane-spanning domain; and (d) a cytoplasmic protein kinase domain that contains all of the 11 subdomains conserved among protein kinases. The RPK1 gene is expressed in flowers, stems, leaves, and roots. Expression of the RPK1 gene is induced within 1 h after treatment with abscisic acid (ABA). The gene is also rapidly induced by several environmental stresses such as dehydration, high salt, and low temperature, suggesting that the gene is involved in a general stress response. The dehydration-induced expression is not impaired in aba-1, abi1-1, abi2-1, and abi3-1 mutants, suggesting that the dehydration-induced expression of the RPK1 gene is ABA-independent. A possible role of this gene in the signal transduction pathway of ABA and the environmental stresses is discussed.

Hong, S W; Jon, J H; Kwak, J M; Nam, H G

1997-01-01

117

Advanced Hardened Antenna Window Materials Study.  

National Technical Information Service (NTIS)

A hardened composite antenna window material designated ADL-10 was developed, based on GE-RESD's Omniweave multidirectional fiber reinforcement woven construction using pure silica fibers and GE SR-350 methyl silicone resin as the matrix. An inorganic sil...

J. P. Brazel

1972-01-01

118

SEMIAUSTENITIC PRECIPITATION-HARDENABLE STAINLESS STEELS  

Microsoft Academic Search

A summary is given of the classification, metallurgy, treatment, and ; properties of the semiaustenitic precipitatson-hardenable stainless steels: 17-7 ; PH, AM 350, AM 355, PH 15-7 Mo, AM 357, and AM 359. (auth);

Ludwigson

1961-01-01

119

Extraordinary strain hardening by gradient structure  

PubMed Central

Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.

Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

2014-01-01

120

Hardening and softening of nanocrystalline materials.  

National Technical Information Service (NTIS)

Nanocrystalline Pd and Cu samples have been thermally treated to determine whether the relation between hardness and grain size depend on the method used to vary the grain sizes. Previous reports indicate that hardening with decreasing grain size resulted...

G. E. Fougere, J. R. Weertman, R. W. Siegel

1993-01-01

121

Dispersion-Hardened Metals and Alloys.  

National Technical Information Service (NTIS)

Significant reports covering the period from 1960 were selected for this study with reference to earlier works. Recent Government-sponsored research has shown that dispersion hardening as a means of enhancing the strength properties of metals and alloys i...

1965-01-01

122

Dispersion Hardened Titanium Alloys by Powder Metallurgy.  

National Technical Information Service (NTIS)

The characteristics and applications of titanium alloys for structural purposes are discussed. A method of producing dispersion hardened titanium alloys through powder metallurgical techniques is described. An electron beam splatting furnace designed for ...

S. Pattanaik K. G. Gopinathan V. S. Arunachalam

1974-01-01

123

Laser transformation hardening of tempered 4340 steel  

Microsoft Academic Search

A CO2 laser with a fixed laser power of 1.8 KW was employed to harden the surface of some AISI 4340 steel specimens, with a scan\\u000a rate from 5 to 10 mm\\/s. The influence of scan rates and tempering treatments of the alloy on the hardness profile and microstructure\\u000a of the laserhardened zone was analyzed. Microstructures in the hardened zone

R. K. Shiue; C. Chen

1992-01-01

124

Work hardening behavior in aluminum alloy 2090  

SciTech Connect

An investigation into the work hardening behavior of an aluminum alloy 2090-T81 Al-3.05Cu-2.16Li-0.12Zr at various test temperatures, heat treatment conditions and microstructures was conducted. One microstructure consisted of unrecrystallized, highly textured grains, and the other microstructure was composed of recrystallized grains. Microstructural effects on work hardening were divided into two levels of contribution: the grain structure level, which consisted of the grain size and shape, subgrains and texture, and the microconsistent level, which included the precipitates and solutes. Two heat treatments were studied: the as-received, peak-aged condition, and the solution heat treated condition where the as-received plate was resolutionized. Observations of the deformed surface of both as-received grain structures at various prestrains indicated that there was no correlation between an increase in slip homogeneity and an increase in work hardening. The increase in out-of-plane grain rotation at lower temperatures was not primarily responsible for the increase in work hardening. In addition, the fully plastic deformation microstructure for the unrecrystallized microstructure appeared very inhomogeneous as the grains deformed in bands; there were also bands of grains that had very little to no deformation. From the work hardening plots it was found that an unrecrystallized, (110)<112> textured grain structure with a homogeneous distribution of subgrains produced the highest rate of work hardening between 300 K and 77 K. When the microconstituents are added to both grain structures, both the work hardening rate in the elastic-plastic and fully plastic regimes and the level of work hardening at which the elastic-plastic to fully plastic transition occurred were affected.

Tseng, C. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

1993-12-01

125

Microstrain in dispersion-hardened steels  

NASA Astrophysics Data System (ADS)

Using high-resolution neutron diffraction, microstrain was investigated in three series of samples of stainless austenitic dispersion-hardened steels, which are used as various structural reactor components. The effect of temperature and duration of heat treatment on the precipitation of dispersion-hardened phase particles, as well as on lattice parameter changes and microstrain, was studied. An increase in microstrain upon coherence failure was observed in all the steels.

Bokuchava, G. D.; Papushkin, I. V.; Sumin, V. V.; Aznabayev, D.; Mukhametuly, B.; Balagurov, A. M.; Sheptyakov, D. V.

2013-03-01

126

Work hardening behavior in aluminum alloy 2090  

Microsoft Academic Search

An investigation into the work hardening behavior of an aluminum alloy 2090-T81 Al-3.05Cu-2.16Li-0.12Zr at various test temperatures, heat treatment conditions and microstructures was conducted. One microstructure consisted of unrecrystallized, highly textured grains, and the other microstructure was composed of recrystallized grains. Microstructural effects on work hardening were divided into two levels of contribution: the grain structure level, which consisted of

Tseng

1993-01-01

127

Hardenability of steels for precision castings  

Microsoft Academic Search

1.The standard medium-carbon steel 45L, widely used for manufacturing cast machine parts, which can be melted in high-frequency induction furnaces with an acid lining, has a high hardenability and tendency to grain growth.2.Steel 50PPL, which can be melted in high-frequency induction furnaces with a basic lining, has a minimal hardenability. The ideal critical diameter of basic 50PPL is 8.6 mm,

K. Z. Shepelyakovskii; Yu. Ya. Postnikov; V. D. Kal'ner; L. S. Danil'chenko

1971-01-01

128

On shakedown analysis in hardening plasticity  

NASA Astrophysics Data System (ADS)

The extension of classical shakedown theorems for hardening plasticity is interesting from both theoretical and practical aspects of the theory of plasticity. This problem has been much discussed in the literature. In particular, the model of generalized standard materials gives a convenient framework to derive appropriate results for common models of plasticity with strain-hardening. This paper gives a comprehensive presentation of the subject, in particular, on general results which can be obtained in this framework. The extension of the static shakedown theorem to hardening plasticity is presented at first. It leads by min-max duality to the definition of dual static and kinematic safety coefficients in hardening plasticity. Dual static and kinematic approaches are discussed for common models of isotropic hardening of limited or unlimited kinematic hardening. The kinematic approach also suggests for these models the introduction of a relaxed kinematic coefficient following a method due to Koiter. Some models for soils such as the Cam-clay model are discussed in the same spirit for applications in geomechanics. In particular, new appropriate results concerning the variational expressions of the dual kinematic coefficients are obtained.

Nguyen, Quoc-Son

2003-01-01

129

Project COLD.  

ERIC Educational Resources Information Center

Describes Project COLD (Climate, Ocean, Land, Discovery) a scientific study of the Polar Regions, a collection of 35 modules used within the framework of existing subjects: oceanography, biology, geology, meterology, geography, social science. Includes a partial list of topics and one activity (geodesic dome) from a module. (Author/SK)

Kazanjian, Wendy C.

1982-01-01

130

Estimation of hardened layer dimensions in laser surface hardening processes with variations of coating thickness  

Microsoft Academic Search

In the laser surface hardening process, a laser absorbing coating should be applied on the workpiece in order to act as a laser beam energy absorber to efficiently absorb expensive laser power. Thus, a suitable choice of coating thickness as well as the coating material should greatly improve the quality of the hardened surface. However, very few researchers have systematically

H. G. Woo; H. S. Cho

1998-01-01

131

Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel  

Microsoft Academic Search

This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik NanoflexŽ and Uddeholm CorraxŽ. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural characterisation of the cases developed included X-ray diffraction analysis, reflected light microscopy and micro-hardness testing. It was found that the incorporation of nitrogen or carbon resulted in

Rasmus B. Frandsen; Thomas Christiansen; Marcel A. J. Somers

2006-01-01

132

Point defect concentrations and solid solution hardening in NiAl with Fe additions  

SciTech Connect

The solid solution hardening behavior exhibited when Fe is added to NiAl is investigated. This is an interesting problem to consider since the ternary Fe additions may choose to occupy either the Ni or the Al sublattice, affecting the hardness at differing rates. Moreover, the addition of Fe may affect the concentrations of other point defects such as vacancies and Ni anti-sites. As a result, unusual effects ranging from rapid hardening to solid solution softening are observed. Alloys with varying amounts of Fe were prepared in Ni-rich (40 at. % Al) and stoichiometric (50 at. % Al) compositions. Vacancy concentrations were measured using lattice parameter and density measurements. The site occupancy of Fe was determined using ALCHEMI. Using these two techniques the site occupancies of all species could be uniquely determined. Significant differences in the defect concentrations as well as the hardening behavior were encountered between the Ni-rich and stoichiometric regimes.

Pike, L.M.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-08-01

133

Rapid determination of mercury species in sewage sludge by high-performance liquid chromatography on-line coupled with cold-vapor atomic-fluorescence spectrometry after ultrasound-assisted extraction.  

PubMed

So far, no research has been focused on the determination of organomercuries in sewage sludge. Here, an ultrasonic extraction method for the rapid determination of methylmercury (MeHg) and ethylmercury (EtHg) in sewage sludge after ultrasound-assisted extraction is proposed. Using TMA (tetramethylammonium hydroxide) as the extractant with 3.0 g copper powder, ultrasonic extraction for 30 min at 70 °C demonstrated to be highly efficient, and was shown a satisfied extraction efficiency for MeHg and EtHg from sewage sludge samples. Determination of mercury species was carried out by high-performance liquid chromatography on-line coupled with cold-vapor atomic fluorescence spectrometry (HPLC-CV-AFS). The obtained results from quality control samples were excellent. The proposed method was also validated by the application to five real samples. The results showed that the developed methodology was practicable and highly reliable. Due to the high toxicity of organomercuries and huge amounts of sewage sludge discharged every year, people should pay particular attention to pollutions from sewage sludge. PMID:21666362

Gao, Erle; Liu, Jianshe

2011-01-01

134

Laser Hardening Prediction Tool Based On a Solid State Transformations Numerical Model  

NASA Astrophysics Data System (ADS)

This paper presents a tool to predict hardening layer in selective laser hardening processes where laser beam heats the part locally while the bulk acts as a heat sink. The tool to predict accurately the temperature field in the workpiece is a numerical model that combines a three dimensional transient numerical solution for heating where is possible to introduce different laser sources. The thermal field was modeled using a kinetic model based on Johnson-Mehl-Avrami equation. Considering this equation, an experimental adjustment of transformation parameters was carried out to get the heating transformation diagrams (CHT). With the temperature field and CHT diagrams the model predicts the percentage of base material converted into austenite. These two parameters are used as first step to estimate the depth of hardened layer in the part. The model has been adjusted and validated with experimental data for DIN 1.2379, cold work tool steel typically used in mold and die making industry. This steel presents solid state diffusive transformations at relative low temperature. These transformations must be considered in order to get good accuracy of temperature field prediction during heating phase. For model validation, surface temperature measured by pyrometry, thermal field as well as the hardened layer obtained from metallographic study, were compared with the model data showing a good adjustment.

Martínez, S.; Ukar, E.; Lamikiz, A.; Liebana, F.

2011-01-01

135

Laser Hardening Prediction Tool Based On a Solid State Transformations Numerical Model  

SciTech Connect

This paper presents a tool to predict hardening layer in selective laser hardening processes where laser beam heats the part locally while the bulk acts as a heat sink.The tool to predict accurately the temperature field in the workpiece is a numerical model that combines a three dimensional transient numerical solution for heating where is possible to introduce different laser sources. The thermal field was modeled using a kinetic model based on Johnson-Mehl-Avrami equation. Considering this equation, an experimental adjustment of transformation parameters was carried out to get the heating transformation diagrams (CHT). With the temperature field and CHT diagrams the model predicts the percentage of base material converted into austenite. These two parameters are used as first step to estimate the depth of hardened layer in the part.The model has been adjusted and validated with experimental data for DIN 1.2379, cold work tool steel typically used in mold and die making industry. This steel presents solid state diffusive transformations at relative low temperature. These transformations must be considered in order to get good accuracy of temperature field prediction during heating phase. For model validation, surface temperature measured by pyrometry, thermal field as well as the hardened layer obtained from metallographic study, were compared with the model data showing a good adjustment.

Martinez, S.; Ukar, E.; Lamikiz, A. [Department of Mechanical Engineering, University of the Basque Country, ETSII, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain); Liebana, F. [Robotiker Technology Centre, Parque Tecnologico, Edif. 202, Zamudio 48170 (Spain)

2011-01-17

136

Recrystallization of Cold Spray-Fabricated CP Titanium Structures  

Microsoft Academic Search

Cold gas dynamic spray (cold spray) is a promising rapid deposition technology in which particles deposit at supersonic velocities.\\u000a The effect of isothermal annealing on recrystallization and mechanical properties of commercial purity (CP) titanium structures\\u000a that were directly fabricated through cold spray deposition is studied. The optimized cold spray parameters led to a dense\\u000a cold spray structure. Results show that

Saden H. Zahiri; Darren Fraser; Mahnaz Jahedi

2009-01-01

137

Precipitation and Hardening in Magnesium Alloys  

NASA Astrophysics Data System (ADS)

Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

Nie, Jian-Feng

2012-11-01

138

Hot, Cold, and Really Cold.  

ERIC Educational Resources Information Center

Describes a physics experiment investigating temperature prediction and the relationship between the physical properties of heat units, melting, dissolving, states of matter, and energy loss. Details the experimental setup, which requires hot and cold water, a thermometer, and ice. Notes that the experiment employs a deliberate counter-intuitive…

Leyden, Michael

1997-01-01

139

Impact of mild temperature hardening on thermotolerance, fecundity, and Hsp gene expression in Liriomyza huidobrensis.  

PubMed

The pea leafminer, Liriomyza huidobrensis, is one of the most important economic insect pests around the world. Its population fluctuates greatly with seasonal change in China, and temperature was thought to be one of the important reasons. In attempt to further explore the impact of disadvantageous temperature on L. huidobrensis, 1-day-old adults were shocked at various temperatures (10, 25, 32, and 35 degrees C, respectively) for 4h, and the effects on thermotolerance, feeding, and fecundity were studied. Meanwhile the expression of five heat shock genes (hsp90, 70, 60, 40, and 20) was examined by real-time quantitative PCR. Our results showed that both 32 and 35 degrees C hardenings remarkably increased adult heat resistance, whereas cold tolerance was not improved accordingly. No cross resistance in response to cold and heat stresses was observed. Both adult feeding and fecundity were dramatically reduced, but no effect was observed on egg hatching, larval survival, pupal eclosion, or sex ratio. The results indicate that the deleterious effect on fecundity is the result of direct cessation of oviposition during the period of stress. Simultaneously, the mRNA levels of hsp70 and hsp20 significantly increased upon thermal hardening. Taken together, our results suggest that mild heat hardening improves thermotolerance of L. huidobrensis at the cost of impairment on fecundity, and the induced expression of hsp70 and hsp20 may play an important role in balancing the functional tradeoff. PMID:17651748

Huang, Li-Hua; Chen, Bing; Kang, Le

2007-12-01

140

Influence of slip system hardening assumptions on modeling stress dependence of work hardening  

NASA Astrophysics Data System (ADS)

Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on the macroscopic flow stress can be quantified in a polycrystal by the average Taylor factor MŻ. Sources of resistance to dislocation motion such as interaction with dislocation structures, precipitates, and grain boundaries, contribute to the elevation of the critically resolved shear strength ?crss. In continuum slip polycrystal formulations, material hardening phenomena are reflected in the slip system hardness equations. Depending on the model, the hardening equations and the mean field assumption can both affect geometric hardening through texture evolution. In this paper, we examine continuum slip models and focus on how the slip system hardening model and the mean field assumption affect the stress-strain response. Texture results are also presented within the context of how the texture affects geometric hardening. We explore the effect of employing slip system hardnesses averaged over different size scales. We first compare a polycrystal simulation employing a single hardness per crystal to one using a latent hardening formulation producing distinct slip system hardnesses. We find little difference between the amplitude of the single hardness and a crystal-average of the latent hardening values. The geometric hardening is different due to the differences in the textures predicted by each model. We also find that due to the high degree of symmetry in an fcc crystal, macroscopic stress-strain predictions using simulations employing crystal- and aggregateaveraged hardnesses are nearly identical. We find this to be true for several different mean field assumptions. An aggregate-averaged hardness may be preferred in light of the difficulty encountered in experimentally verifying slip system strength in a polycrystal. We also examine model performance under different stress states. We find that, due to a higher degree of geometric softening in torsion, the latent hardening model more closely correlates oxygen free high conductivity copper compression and torsion data than the aggregate-averaged model. Both models predicted similar material hardening rates in torsion and compression, however. Finally, we propose an aggregate-averaged hardening equation with a heightened dependence on the Taylor factor as defined by the average crystal shearing rate that predicts a higher material hardening rate in compression as compared to torsion to correlate the data. We then use the model to predict compression followed by torsion results.

Miller, Matthew; Dawson, Paul

1997-11-01

141

Coping with Cold Sores  

MedlinePLUS

... What's that? Adam wondered. What Is a Cold Sore? Cold sores are small blisters that is reddish ... always found inside the mouth.) What Causes Cold Sores? Cold sores are caused by a virus called ...

142

A novel radiation hardened by design latch  

NASA Astrophysics Data System (ADS)

Due to aggressive technology scaling, radiation-induced soft errors have become a serious reliability concern in VLSI chip design. This paper presents a novel radiation hardened by design latch with high single-event-upset (SEU) immunity. The proposed latch can effectively mitigate SEU by internal dual interlocked scheme. The propagation delay, power dissipation and power delay product of the presented latch are evaluated by detailed SPICE simulations. Compared with previous SEU-hardening solutions such as TMR-Latch, the presented latch is more area efficient, delay and power efficient. Fault injection simulations also demonstrate the robustness of the presented latch even under high energy particle strikes.

Zhengfeng, Huang; Huaguo, Liang

2009-03-01

143

Eddy current measurements on case hardened steel  

NASA Astrophysics Data System (ADS)

The case-hardening process modifies the near-surface permeability and conductivity of steel, as can be observed through changes in eddy current probe signals measured over a range of frequency. In this work, experiments have been performed using normal absolute probe coils on flat steel specimens and coils encircling case-hardened steel rods. By fitting model results to the experimental data, estimates of electrical material properties are found. The approach also allows an assessment of the sensitivity of the measurements to the case depth. .

Sun, H.; Bowler, J. R.; Bowler, N.; Johnson, M. J.

2002-05-01

144

Radiation Hardened Electronics for Space Environments (RHESE)  

NASA Technical Reports Server (NTRS)

Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

2007-01-01

145

Hardening against a combined electromagnetic threat  

NASA Astrophysics Data System (ADS)

Hardening against the electromagnetic environment is usually done by considering each threat separately. In recent years, there has been an increasing interest in methods for unifying electromagnetic standards and procedures to simplify the design and testing of hardening techniques. This approach is appealing as it could reduce the cost of system design as well as the cost of testing. The objective of this paper is twofold: firstly, to assess the feasibility of combining the various electromagnetic threats to simplify the design of electromagnetic protection; and secondly, to assess the feasibility of using a single test, or at least a minimum number of tests, to verify the electromagnetic hardness of a system.

Dion, M.; Gardner, C.; Kashyap, S.

1995-03-01

146

Laser transformation hardening of a high-purity iron-carbon-chromium alloy  

SciTech Connect

Successful laser transformation hardening of steel surfaces requires that the absorbed laser energy is sufficient to austenitize the initial microstructure to a depth of 0.5 mm or more. Hardening is accomplished when rapid cooling by conduction of heat away from the surface causes transformation of the austenite layer to martensite. Heating and cooling rates of 10/sup 4/ K/s or greater are typical of the laser hardening process and the entire thermal cycle may be accomplished in less than 0.1 s. In an earlier study, laser surface hardening of commercial plain carbon and chromium alloyed steels was examined. It was shown that in the alloyed steel chromium enrichment of the cementite in the initial microstructure could prevent complete transformation of pearlite to asutenite during the very rapid laser heating cycle. However, interpretation of the results was complicated somewhat by the fact that manganese was also partitioned to the cementite. The purpose of this work was to conduct selected identical laser heating experiments on a high-purity Fe-C-Cr alloy to test the effect of chromium unequivocally, i.e., in the absence of manganese and other elements normally present in commercial steels.

Bradley, J.R.; Kim, S.

1989-01-01

147

Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers  

SciTech Connect

The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

Chisholm, Claire [University of California, Berkeley & LBNL; Bei, Hongbin [ORNL; Lowry, M. B. [University of California, Berkeley; Oh, Jason [Hysitron, Inc., MN; Asif, S.A. Syed [Hysitron, Inc., MN; Warren, O. [Hysitron, Inc., MN; Shan, Zhiwei [Xi'an Jiaotong University, China & Hysitron, Inc., MN; George, Easo P [ORNL; Minor, Andrew [University of California, Berkeley & LBNL

2012-01-01

148

Medical problems from cold exposure  

Microsoft Academic Search

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use

Dembert

1982-01-01

149

Structural Changes in Thylakoid Proteins during Cold Acclimation and Freezing of Winter Rye (Secale cereale L. cv. Puma) 1  

PubMed Central

Thylakoids were isolated from nonhardened and cold-hardened winter rye (Secale cereale L. cv. Puma), and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence and absence of sulfhydryl reagents. Electrophoresis of cold-hardened rye thylakoid proteins revealed the presence of a 35 kilodalton polypeptide and the absence of a 51 kilodalton polypeptide found in nonhardened rye thylakoid proteins. The 35 kilodalton band could be induced by adding ?-mercaptoethanol to nonhardened rye thylakoid proteins, whereas the 51 kilodalton band could be formed by adding cupric phenanthroline to these same proteins. Sulfhydryl group titration showed that cold-hardened rye thylakoid proteins contained more free sulfhydryls than nonhardened rye proteins. Although amino acid analysis of thylakoid proteins revealed quantitative differences in several amino acid residues, the polarity of thylakoid proteins did not change during cold acclimation. No significant changes in sodium dodecyl sulfate-polyacrylamide gels of thylakoid proteins appeared when either nonhardened or cold-hardened plants were frozen in vivo or in vitro. However, thylakoid proteins did aggregate when frozen in the presence of ?-mercaptoethanol. Although thylakoid proteins isolated from cold-hardened rye contained more reduced thiols, a general state of reduction did not act as a cryoprotectant. It is hypothesized that conformational changes of specific proteins may be important for low temperature growth of rye. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4

Griffith, Marilyn; Brown, Gregory N.; Huner, Norman P. A.

1982-01-01

150

Radiation Effects and Hardening Techniques for Spacecraft Microelectronics  

NASA Astrophysics Data System (ADS)

The natural radiation from the Van Allen belts, solar flares, and cosmic rays found outside of the protection of the earth's atmosphere can produce deleterious effects on microelectronics used in space systems. Historically civil space agencies and the commercial satellite industry have been able to utilize components produced in special radiation hardened fabrication process foundries that were developed during the 1970s and 1980s under sponsorship of the Departments of Defense (DoD) and Energy (DoE). In the post--cold war world the DoD and DoE push to advance the rad--hard processes has waned. Today the available rad--hard components lag two-plus technology node generations behind state- of-the-art commercial technologies. As a result space craft designers face a large performance gap when trying to utilize available rad--hard components. Compounding the performance gap problems, rad--hard components are becoming increasingly harder to get. Faced with the economic pitfalls associated with low demand versus the ever increasing investment required for integrated circuit manufacturing equipment most sources of rad--hard parts have simply exited this market in recent years, leaving only two domestic US suppliers of digital rad--hard components. This paper summarizes the radiation induced mechanisms that can cause digital microelectronics to fail in space, techniques that can be applied to mitigate these failure mechanisms, and ground based testing used to validate radiation hardness/tolerance. The radiation hardening techniques can be broken down into two classes, Hardness By Process (HBP) and Hardness By Design (HBD). Fortunately many HBD techniques can be applied to commercial fabrication processes providing space craft designer with radiation tolerant Application Specific Integrated Circuits (ASICs) that can bridge the performance gap between the special HBP foundries and the commercial state-of-the-art performance.

Gambles, J. W.; Maki, G. K.

2002-01-01

151

Laser Transformation Hardening of Firing Zone Cutout Cams.  

National Technical Information Service (NTIS)

This manufacturing technology (MT) project developed techniques to use laser transformation hardening to replace cyanide salt bath nitriding to case harden firing zone cutout cams for the Mk 10 Guided Missile Launcher System (GMLS). These cams, machined o...

R. W. Lowry

1981-01-01

152

Technology Developments in Radiation-Hardened Electronics for Space Environments.  

National Technical Information Service (NTIS)

The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to...

A. S. Keys J. T. Howell

2008-01-01

153

Laser hardening of Diesel engine valve  

Microsoft Academic Search

The present article submits the results of complex investigations of the effect of laser treatment on the structure and properties of steel 40KhlOS2M and of engine tests with Diesel engine valves hardened by the newly devised technology. Laser treatment was carried out with a continuous CO2 laser \\

A. P. Androsov; S. I. Aleksenko; M. V. Boyarkin; V. G. Kusidis; V. I. Petrov

1988-01-01

154

Extraordinary strain hardening by gradient structure.  

PubMed

Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T

2014-05-20

155

Photoactive coating for hardening optical fibers  

Microsoft Academic Search

In accordance with the foregoing principles and objects of the present invention, an improved optical fiber structure is provided which is hardened against the effects of ionizing nuclear radiation and comprises a conventional plastic, glass or silica optical fiber core and cladding, having an additional outer coating comprising phosphorescent or luminescent material for interacting with the ionizing radiation to provide

Caldwell

1982-01-01

156

Fatigue of coated and laser hardened steels.  

National Technical Information Service (NTIS)

In the present work the effect of ion nitriding, laser hardening and hot dip galvanizing upon the fatigue limit and notch sensitivity of a B-Mn Swedish steel SS 2131 have been investigated. The fatigue tests were performed in plane reverse bending fatigue...

P. La Cruz

1990-01-01

157

High Explosive Testing of Hardened Aircraft Shelters.  

National Technical Information Service (NTIS)

Two full-size, hardened, third-generation aircraft shelters of the type employed by the U.S. Air Force in Europe and by NATO countries were subjected to a series of five high explosive tests. The purpose of the tests (nicknamed DISTANT RUNNER) was to gath...

R. R. Bousek

1983-01-01

158

Password hardening based on keystroke dynamics  

Microsoft Academic Search

We present a novel approach to improving the security of passwords. In our approach, the legitimate user's typing patterns (e.g., durations of keystrokes, and latencies between keystrokes) are combined with the user's password to generate a hardened password that is convincingly more secure than conventional passwords against both online and offline attackers. In addition, our scheme automatically adapts to gradual

Fabian Monrose; Michael K. Reiter; Susanne Wetzel

1999-01-01

159

Solid-solution softening and hardening  

Microsoft Academic Search

The bases for models of solid-solution softening and hardening are ; discussed. Conclusions of these discussions are presented which show that most ; intrinsic mechanisms cannot be applied to solution softening in Ta and Nb alloys. ; Scavenging-like mechanisms, related to effects that solute interactions have on ; the strain center density, strength or distribution in materials which are ;

R. Gibala; T. E. Mitchell

1973-01-01

160

Cold Stowage Flight Systems  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aide researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials. Details of these current technologies will be provided along with operational experience gained to date. With shuttle retirement looming, NASA has protected the capability to provide a temperature controlled environment during transportation to and from the ISS with the use of Glacier and Coldbags, which are compatible with future commercial vehicles including SpaceX's Dragon Capsule, and Orbital s Cygnus vehicle. This paper will discuss the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

Campana, Sharon

2010-01-01

161

Cold Stowage Flight Systems  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aid researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials to maintain temperature. Details of these current technologies are provided along with operational experience gained to date. This paper discusses the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

Campana, Sharon E.; Melendez, David T.

2011-01-01

162

On the Optimization of Compressibility and Hardenability of Sinter-Hardenable PM Steels  

NASA Astrophysics Data System (ADS)

Sinter-hardenable steel powders eliminate the extra steps normally required for heat treating since they allow for direct quenching of components at the end of the sintering cycle with a forced convection cooling unit. The current article presents the results of the effect of the alloying method on the optimization of compressibility and sinter-hardenability of sinter-hardenable PM steels. Water-atomized steel powders were produced. Two successive designs of experiments were used to optimize the chemical composition with prealloyed (nickel, chromium, molybdenum, and manganese) and admixed elements (nickel, chromium, manganese, and copper). Static mechanical properties were also characterized. Results show that among all of the combinations of chemical elements and within the range of concentrations studied, the optimum sinter-hardenable powder had the following prealloyed chemistry: 1.5 wt pct Ni, 1 to 1.25 wt pct Mo, and 0.40 to 0.55 wt pct Cr.

Gigučre, Nicolas; Blais, Carl

2013-10-01

163

PID control of laser surface hardening of steel  

Microsoft Academic Search

We discuss control strategies for the laser surface hardening of steel. The goal is to achieve a prescribed hardening depth avoiding surface melting. Our mathematical model consists of a system of ordinary differential equations (ODEs) for the phase volume fractions coupled with the heat equation. The system is solved semi-implicitely using the finite element method. To obtain a uniform hardening

Dietmar Hömberg; Wolf Weiss

2006-01-01

164

Laser-beam hardening and alloying of machine parts  

Microsoft Academic Search

The technical specifications of some repetitively pulsed and CW lasers used for the hardening and alloying of metal parts are presented, and processes of laser-beam hardening, microalloying, and amorphization are described. The optimum regimes of laser-beam hardening are determined. The effect of laser treatments on the service-related properties of metal materials is assessed.

Vladimir S. Kovalenko; Leonid F. Golovko; Viktor S. Chernenko

1990-01-01

165

COMPUTER SIMULATION OF INDUCTION SURFACE HARDENING AXIALLY SYMMETRIC WORKPIECES  

Microsoft Academic Search

To achieve a higher quality process planning and a more flexible execution of induction hardening computer simulation of electromagnetic and thermodynamic processes as well as microstructural transformation is recommended. This paper describes and suggests an own simulation model of the induction hardening process and explains a special simulation program that has be en developed for the surface induction hardening of

Darko Landek; Franjo Cajner; Tomislav Filetin

166

A Study of Strain Hardening in Polysulfide Sealants  

Microsoft Academic Search

Four typical polysulfide building sealants were investigated for possible strain hardening during a simulated ten (10) year service life Hardening of the specimens was checked by Durometer and by Modulus, creep, stress relaxation and cyclic load curves. No appreciable hardening was found as a result of 3,000 load cycles. The effects of aging and weathering were not included in the

Scott Stargel

1971-01-01

167

Technology Developments in Radiation-Hardened Electronics for Space Environments  

Microsoft Academic Search

The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various

Andrew S. Keys; Joe T. Howell

168

Common cold  

PubMed Central

Introduction Each year, children suffer up to 5 colds and adults have 2-3 infections, leading to time off school or work, and considerable discomfort. Most symptoms resolve within a week, but coughs often persist for longer. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for common cold? We searched: Medline, Embase, The Cochrane Library and other important databases up to May 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 19 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: analgesics or anti-inflammatory drugs, antibiotics, antihistamines, decongestants (norephedrine, oxymetazoline, or pseudoephedrine), decongestants plus antihistamine, echinacea, steam inhalation, vitamin C, and zinc (intranasal gel or lozenges).

2008-01-01

169

Common cold  

PubMed Central

Introduction Each year, children suffer up to 5 colds and adults have two to three infections, leading to time off school or work, and considerable discomfort. Most symptoms resolve within 1 week, but coughs often persist for longer. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for common cold? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 21 systematic reviews and RCTs that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: analgesics or anti-inflammatory drugs, antibiotics, antihistamines, decongestants for short-term and for long-term relief, decongestants plus antihistamines, echinacea, steam inhalation, vitamin C, and zinc (intranasal gel or lozenges).

2011-01-01

170

Predictive modeling of multi-track laser hardening of AISI 4140 steel  

Microsoft Academic Search

Laser hardening provides benefits over the conventional hardening processes, including minimum distortion in the parts and the absence of a quenchant. This process is also faster than conventional hardening processes and can be used for selective hardening of specific areas of components. One known problem with laser hardening in steels, however, is back tempering when a large area is hardened

Ritesh S. Lakhkar; Yung C. Shin; Matthew John M. Krane

2008-01-01

171

Laser surface hardening of ductile cast iron for vehicle die  

NASA Astrophysics Data System (ADS)

Experiments of laser transformation hardening were performed with various process parameters on the surface of ductile cast iron block, which is often used for vehicle body. The distribution of microhardness along the case depth direction and the variation of microstructure of hardened track were investigated. Wear test was carried out using a ball-on-flat-type wear-test machine. The results indicate that the hardened layers after the laser surface hardening treatment have excellence wear resistance. It is seen that the surface hardness of ductile cast iron blocks increases greatly at suitable values of process parameters in laser transformation hardening, which satisfies the vehicle dies.

Xu, Yanghui; Liu, Jichang

2010-11-01

172

Theoretical and experimental studies on laser transformation hardening of steel by customized beam  

Microsoft Academic Search

An exact solution was developed for a quasi-steady-moving-interface heat transfer problem in laser transformation hardening by a beam customized to a flat-top rectangular shape. The absorption and release of the latent heat were taken into account. The solution provided the body temperature, heating rate, and subsequent cooling rate. Using the IT and CCT diagrams, the rapid austenitization and pearlitic\\/martensitic phase

Michael K. H. Leung; H. C. Man; J. K. Yu

2007-01-01

173

Microstructures and mechanical properties of boride-dispersed precipitation-hardening stainless steels produced by RST  

Microsoft Academic Search

Two commercial precipitation-hardening (PH) stainless steels were modified with 2.64 to 2.86 wt% Ti and 1.2 to 1.3 wt% B via rapid solidification technology (RST) and powder metallurgy (PM). The resulting alloys exhibited improved tensile and yield strengths over their commercial PH stainless steel counterparts at room and elevated temperatures. Ductility improvements at elevated temperatures were also observed. The improved

Steve Hahn; Saul Isserow; Ranjan Ray

1987-01-01

174

Cyclic hardening in bundled actin networks.  

PubMed

Nonlinear deformations can irreversibly alter the mechanical properties of materials. Most soft materials, such as rubber and living tissues, display pronounced softening when cyclically deformed. Here we show that, in contrast, reconstituted networks of crosslinked, bundled actin filaments harden when subject to cyclical shear. As a consequence, they exhibit a mechano-memory where a significant stress barrier is generated at the maximum of the cyclic shear strain. This unique response is crucially determined by the network architecture: at lower crosslinker concentrations networks do not harden, but soften showing the classic Mullins effect known from rubber-like materials. By simultaneously performing macrorheology and confocal microscopy, we show that cyclic shearing results in structural reorganization of the network constituents such that the maximum applied strain is encoded into the network architecture. PMID:21139579

Schmoller, K M; Fernández, P; Arevalo, R C; Blair, D L; Bausch, A R

2010-01-01

175

Contact allergy to aziridine paint hardener.  

PubMed

A painter experienced an extensive dermatitis when exposed to a paint primer (undercoating) used to protect wood siding. The primer was an acrylic emulsion with a polyfunctional aziridine added as a self-curing cross-linker or hardener. The polyfunctional aziridine cross-linker was made by reacting propyleneimine with a polyfunctional acrylate, trimethylolpropane triacrylate (TMPTA). Our patient reacted to the cross-linker and also reacted to TMPTA, which is present in excess in the cross-linker. He also cross-reacted to pentaerythritol triacrylate (PETA). Both TMPTA and PETA can be used in the production of aziridine hardeners and both are well known as sensitizers in radiation-dried acrylic printing inks and coatings. PMID:3156563

Cofield, B G; Storrs, F J; Strawn, C B

1985-03-01

176

Terminal modeling of hardened integrated circuits  

NASA Astrophysics Data System (ADS)

Kleiner et al. (1979) have reported modeling and test verification techniques used to develop medium-scale, dielectrically isolated integrated circuits (DIIC). The current investigation is concerned with the approaches employed in modeling the new circuits for applications studied by design and radiation hardening engineers. The described technique improves significantly the cost-effective application of computer programs such as SYSCAP II. The terminal model offers the designer of radiation-hardened electronic circuits a method for evaluating the effects of radiation transients on single or multiple piece-part response at the circuit board level. Although the models presented were intended for TREE design and analysis, it is possible to extend the technique to EMP and SGEMP evaluations.

Kleiner, C. T.; Haas, R.; Peacock, M.; Mandel, G.; Messenger, G. C.; Weakley, D.; Demartino, V.

1981-12-01

177

A Fundamental Study of Laser Transformation Hardening  

Microsoft Academic Search

A theoretical and experimental study of heat flow and solid-state phase transformations during the laser surface hardening\\u000a of 1018 steel was conducted. In the theoretical part of the study, a three-dimensional heat flow model was developed using\\u000a the finite difference method. The surface heat loss, the temperature dependence of the surface absorptivity, and the temperature\\u000a dependence of thermal properties were

Sindo Kou; D. K. Sun; Y. P. Le

1983-01-01

178

Evaluating quenchants and facilities for hardening steel  

Microsoft Academic Search

The effects of agitation and quenchant temperature on the ability of a fast oil, water, and a 16 pct solution of a polyglycol\\u000a in water to remove heat from steel during quenching have been determined using instrumented probes and bars of known hardenability.\\u000a The fast oil was relatively insensitive to quenchant velocity in the range of 0 to 1 m\\/s

R. W. Monroe; C. E. Bates

1983-01-01

179

Factors affecting the inherent hardenability of steel  

Microsoft Academic Search

The hardenability of a steel depends upon the actual rate at which its austenite transforms to fine pearlite at the particular\\u000a temperature at which this reaction sets in most promptly. The precise temperature at which this transformation rate is greatest\\u000a depends upon the composition of the steel; in any case, it is this maximum rate at temperatures near 950 degrees

Edgar Collins Bain

1979-01-01

180

Strain hardening in underaged INCONEL 718  

Microsoft Academic Search

INCONEL 718 is a commercial, precipitation-hardenable nickel iron-base superalloy, strengthened primarily by precipitates of the metastable [gamma][double prime] phase which is based on the composition Ni[sub 3]Nb and has an ordered body-centered tetragonal (DO[sub 22]) structure. An earlier investigation on the deformation mechanisms in this alloy has shown that [gamma][double prime] precipitates are sheared by the passage of true crystallographic

M. Sundararaman; R. Kishore; P. Mukhopadhyay

1994-01-01

181

Bias-hardened CMB lensing with polarization  

NASA Astrophysics Data System (ADS)

Polarization data will soon provide the best method for measuring the CMB lensing potential, although these data are potentially sensitive to several instrumental effects, including beam asymmetry, polarization angle uncertainties and sky coverage, as well as analysis choices, such as masking. We derive bias-hardened lensing estimators to mitigate these effects, at the expense of larger reconstruction noise, and we test them numerically on simulated data. We find that the mean-field bias from masking is significant for the EE quadratic lensing estimator. On the one hand, the bias-hardened estimator combined with filtering techniques can mitigate the mean field. On the other hand, the EB estimator does not significantly suffer from the mean field due to the point source masks and survey window function. However, the contamination from beam asymmetry and polarization angle uncertainties can generate mean-field biases for the EB estimator. These can also be mitigated using bias-hardened estimators, with at most a factor of ˜3 degradation of noise level compared to the conventional approach.

Namikawa, Toshiya; Takahashi, Ryuichi

2014-02-01

182

Pulsed laser surface hardening of ferrous alloys.  

SciTech Connect

A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

1999-09-30

183

Dermatitis from aziridine hardener in printing ink.  

PubMed

13 of 51 workers developed dermatitis of the hands and face after handling a water-based ink containing a polyfunctional aziridine hardening agent. Improper work practices resulted in skin contamination with the ink and its ingredients. The aziridine hardener contained trimethylolpropane triacrylate (TMPTA). The incidence of dermatitis was highest among the ink mixers who handled the undiluted aziridine (6 of 8 workers affected), was lower among printers who handled ink containing 2 to 4% aziridine (7 of 22 workers affected), and was absent in workers who did not handle ink. The mean latency from first contact with the ink to the development of the rash was 3.2 months among the ink mixers, and 6.2 months among the printers. The present findings demonstrate the risk of handling aziridine hardeners when protective clothing is not properly used and when work practices result in direct skin contact. Further research should be performed to discern whether aziridine compounds themselves, free of TMPTA, can cause dermatitis. PMID:3160531

Garabrant, D H

1985-04-01

184

Cold confusion  

SciTech Connect

On March 23 two chemists, Martin Fleischmann and Stanley Pons startled the world with a press conference at the University of Utah where they announced that they had achieved nuclear fusion at room temperatures. As evidence they cited the production of ''excess'' amounts of heat in an electrochemical apparatus and observation of neutron production. While the production of heat in a chemical apparatus is not in itself unusual the observation of neutrons is certainly extraordinary. As it turned out, though, careful measurements of the neutron production in electrochemical apparatus similar to that used by Fleischmann and Pons carried out at dozens of other laboratories has shown that the neutron production fails by many orders of magnitude to support the assertion by Fleischmann and Pons that their discovery represents a new and cheap source of fusion power. In particular, independent measurements of the neutron production rate suggest that the actual rate of fusion energy production probably does not exceed 1 trillionth of a watt. This paper discusses the feasibility that cold fusion is actually being achieved. 7 refs.

Chapline, G.

1989-07-01

185

Protective coatings of metal surfaces by cold plasma treatment  

NASA Technical Reports Server (NTRS)

The cold plasma techniques for deposition of various types of protective coatings are reviewed. The main advantage of these techniques for deposition of ceramic films is the lower process temperature, which enables heat treating of the metal prior to deposition. In the field of surface hardening of steel, significant reduction of treatment time and energy consumption were obtained. A simple model for the plasma - surface reactions in a cold plasma system is presented, and the plasma deposition techniques are discussed in view of this model.

Manory, R.; Grill, A.

1985-01-01

186

Empirical beam hardening correction (EBHC) for CT  

SciTech Connect

Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern C-arm CT scanner (Axiom Artis dTA, Siemens Healthcare, Forchheim, Germany). A large variety of phantom, small animal, and patient data were used to demonstrate the data and system independence of EBHC. Results: Although no physics apart from the initial segmentation procedure enter the correction process, beam hardening artifacts were significantly reduced by EBHC. The image quality for clinical CT, micro-CT, and C-arm CT was highly improved. Only in the case of C-arm CT, where high scatter levels and calibration errors occur, the relative improvement was smaller. Conclusions: The empirical beam hardening correction is an interesting alternative to conventional iterative higher order beam hardening correction algorithms. It does not tend to over- or undercorrect the data. Apart from the segmentation step, EBHC does not require assumptions on the spectra or on the type of material involved. Potentially, it can therefore be applied to any CT image.

Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, 91052 Erlangen (Germany)

2010-10-15

187

Laser quench hardening of steel: Effects of superimposed elastic pre-stress on the hardness and residual stress distribution  

NASA Astrophysics Data System (ADS)

Cold drawn AISI 4140 beams were LASER surface hardened with a 2 kW CO2 LASER. Specimens were treated in the free state and while restrained in a bending fixture inducing surface tensile stresses of 94 and 230 MPa. Knoop hardness indentation was used to evaluate the through thickness hardness distribution, and a layer removal methodology was used to evaluate the residual stress distribution. Results showed the maximum surface hardness attained was not affected by pre-stress during hardening, and ranged from 513 to 676 kg/mm2. The depth of effective hardening varied at different magnitudes of pre-stress, but did not vary proportionately to the pre-stress. The surface residual stress, coinciding with the maximum compressive residual stress, increased as pre-stress was increased, from 1040 MPa for the nominally treated specimens to 1270 MPa for specimens pre-stressed to 230 MPa. The maximum tensile residual stress observed in the specimens decreased from 1060 MPa in the nominally treated specimens to 760 MPa for specimens pre-stressed to 230 MPa. Similarly, thickness of the compressive residual stress region increased and the depth at which maximum tensile residual stress occurred increased as the pre-stress during treatment was increased Overall, application of tensile elastic pre-stress during LASER hardening is beneficial to the development of compressive residual stress in AISI 4140, with minimal impact to the hardness attained from the treatment. The newly developed approach for LASER hardening may support efforts to increase both the wear and fatigue resistance of parts made from hardenable steels.

Meserve, Justin

188

Cold worked high alloy ultra-high strength steels with aged martensite structure  

Microsoft Academic Search

Purpose: The study on structure-property relations of heavily cold worked and aged martensite in two high- alloy structural steels was presented. The aim was to understand properties of the sheet products better and thus extend applications of the newly developed cobalt-free maraging and precipitation hardening stainless steels. Design\\/methodology\\/approach: Mechanical tests were performed on cold rolled and aged specimens. Microstructures were

S. J. Pawlak; H. J. Krzto?

189

Medical problems from cold exposure  

SciTech Connect

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems.

Dembert, M.L.

1982-01-01

190

Medical problems from cold exposure.  

PubMed

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems. PMID:7055030

Dembert, M L

1982-01-01

191

Influence of aging on the relaxation and internal friction properties of cold drawn pearute  

Microsoft Academic Search

Rolled wire of eutectoid steel containing approximately 0.8% carbon is particularly suitable for hardening by cold drawing. When drawn it acquires exceptional mechanical strength, so that it can transform int the strongest material known, apart from the thinnest metal wiskers. Lamellar pearlite is obtained by isothermally annealing (patenting) austenite at temperatures between 720 and 450° C, the interlamellar spacing being

P. P. Ravera; R. L. Colombo; D. Firrao

1984-01-01

192

Hardness survey of cold-worked and heat-treated JBK-75 stainless steel alloy  

Microsoft Academic Search

The alloy JBK-75, an age-hardenable austenitic stainless steel, is similar to commercial A-286, but has certain chemistry modifications to improve weldability and hydrogen compatibility. The principal changes are an increase in nickel and a decrease in manganese with lower limits on carbon, phosphorus, sulfur, silicon, and boron. In this study, the effects of solutionizing time and temperature, quench rate, cold

R. J. Jackson; R. L. Lucas

1977-01-01

193

Process Simulation of Cold Pressing and Sintering of Armstrong CP-Ti Powders  

Microsoft Academic Search

A computational methodology is presented for the process simulation of cold pressing and sintering of Armstrong CP-Ti powders. Since the powder consolidation is governed by specific pressure-dependent constitutive equations, solution algorithms were developed for the ABAQUS user material subroutine, UMAT, for computing the plastic strain increments based on an implicit integration of the nonlinear yield function, flow rule, and hardening

Sarma B Gorti; Adrian S Sabau; William H Peter; Stephen D Nunn; Yukinori Yamamoto; Wei Chen

2011-01-01

194

The prediction of case depth in laser transformation hardening  

Microsoft Academic Search

An approximate heat flow model is developed to predict the case depth in laser transformation hardening of steel surfaces.\\u000a The model exploits the dimensional relationships between the process variables to give master diagrams for the hardened depth\\u000a using Gaussian and uniform, rectangular sources. Critical values of dimensionless parameters are identified which predict\\u000a the conditions for first hardening and the onset

H. R. Shercliff; M. F. Ashby

1991-01-01

195

Optimization of Laser Beam Transformation Hardening by One Single Parameter  

Microsoft Academic Search

The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth.\\u000a\\u000aIt has been proved that with a constant hardening depth the results hardness. residual stress. etc.) can

J. Meijer; Sprang van I

1991-01-01

196

Theoretical and experimental analysis of electric contact surface hardening of ductile iron  

NASA Astrophysics Data System (ADS)

Electric contact surface hardening was based on the application of contact resistance heating between the electrode and work piece, which makes use of the rapid and cooling cycles produced on metals surface without affecting the bulk of the work piece. Surface performance can be enhanced through the phase transformations that take place during the mentioned thermal cycles. In this work, the temperature field of strengthened layer on electric contact strengthening was simulated using ANSYS software; the depth and width of strengthened layer were calculated. Moreover, the effect of main processing parameters on strengthened layer was simulated. Finally, some experiments have been carried out to harden the surface of ductile iron by self-developed electric contact surface strengthening device to verify the simulated results. It is found that the error was controlled in 15% reposefully, which represents the simulated result and experimental results to a certain degree are in good agreement.

Qi, Xiaoben; Zhu, Shigen; Ding, Hao; Xu, Mengkuo

2014-01-01

197

Technology Developments in Radiation-Hardened Electronics for Space Environments  

NASA Technical Reports Server (NTRS)

The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS, Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches. System level applications for the RHESE technology products are discussed.

Keys, Andrew S.; Howell, Joe T.

2008-01-01

198

Strain Hardening of Fractal Colloidal Gels  

NASA Astrophysics Data System (ADS)

We report on experiments on the rheology of gels formed by diffusion-limited aggregation of neutrally buoyant colloidal particles. These gels form very weak solids, with the elastic modulus, G'\\(?\\), larger than the loss modulus, G''\\(?\\), and with both G'\\(?\\) and G''\\(?\\) exhibiting only a very weak frequency dependence. Upon small but finite strains ?<0.45 the elastic modulus increases roughly exponentially with ?2. We explain the observed strain hardening with the highly nonlinear elastic response of the rigid backbone of the gel to elongational deformation.

Gisler, T.; Ball, R. C.; Weitz, D. A.

1999-02-01

199

Photoactive coating for hardening optical fibers  

SciTech Connect

In accordance with the foregoing principles and objects of the present invention, an improved optical fiber structure is provided which is hardened against the effects of ionizing nuclear radiation and comprises a conventional plastic, glass or silica optical fiber core and cladding, having an additional outer coating comprising phosphorescent or luminescent material for interacting with the ionizing radiation to provide a source of light to optically bleach the fiber core of optical absorption sites produced as a result of the interaction of the ionizing radiation with the fiber core material.

Caldwell, R.S.

1982-07-29

200

Sulfate attack on hardened cement paste  

SciTech Connect

Hardened cement paste specimens made with different cement types and varying water-cement ratios (w/c) were immersed in 5% sodium sulfate solution maintained at constant pH value of 6. The distribution curves for ettringite, gypsum, and portlandite phases were obtained by using layer by layer XRD analysis and interpreted in terms of material damage due to sulfate attack. The mechanism of sulfate attack is evaluated in regard to the leaching of Ca(OH)[sub 2] and formation of gypsum and ettringite.

Wang, J.G. (Shenzhen Univ. (China). Dept. of Applied Chemistry)

1994-01-01

201

On cold spots in tumor subvolumes.  

PubMed

Losses in tumor control are estimated for cold spots of various "sizes" and degrees of "cold dose." This question is important in the context of intensity modulated radiotherapy where differential dose-volume histograms (DVHs) for targets that abut a critical structure often exhibit a cold dose tail. This can be detrimental to tumor control probability (TCP) for fractions of cold volumes even as small as 1%, if the cold dose is lower than the prescribed dose by substantially more than 10%. The Niemierko-Goitein linear-quadratic algorithm with gamma50 slope 1-3 was used to study the effect of cold spots of various degrees (dose deficit below the prescription dose) and size (fractional volume of the cold dose). A two-bin model DVH has been constructed in which the cold dose bin is allowed to vary from a dose deficit of 1%-50% below prescription dose and to have volumes varying from 1% to 90%. In order to study and quantify the effect of a small volume of cold dose on TCP and effective uniform dose (EUD), a four-bin DVH model has been constructed in which the lowest dose bin, which has a fractional volume of 1%, is allowed to vary from 10% to 45% dose deficit below prescription dose. The highest dose bin represents a simultaneous boost. For fixed size of the cold spot the calculated values of TCP decreased rapidly with increasing degrees of cold dose for any size of the cold spot, even as small as 1% fractional volume. For the four-subvolume model, in which the highest dose bin has a fractional volume of 80% and is set at a boost dose of 10% above prescription dose, it is found that the loss in TCP and EUD is moderate as long as the cold 1% subvolume has a deficit less than approximately 20%. However, as the dose deficit in the 1% subvolume bin increases further it drives TCP and EUD rapidly down and can lead to a serious loss in TCP and EUD. Since a dose deficit to a 1% volume of the target that is larger than 20% of the prescription dose may lead to serious loss of TCP, even if 80% of the target receives a 10% boost, particular attention has to be paid to small-volume cold regions in the target. The effect of cold regions on TCP can be minimized if the EUD associated with the target DVH is constrained to be equal to or larger than the prescription dose. PMID:12148742

Tomé, Wolfgang A; Fowler, Jack F

2002-07-01

202

Cold Signaling and Cold Response in Plants  

PubMed Central

Plants are constantly exposed to a variety of environmental stresses. Freezing or extremely low temperature constitutes a key factor influencing plant growth, development and crop productivity. Plants have evolved a mechanism to enhance tolerance to freezing during exposure to periods of low, but non-freezing temperatures. This phenomenon is called cold acclimation. During cold acclimation, plants develop several mechanisms to minimize potential damages caused by low temperature. Cold response is highly complex process that involves an array of physiological and biochemical modifications. Furthermore, alterations of the expression patterns of many genes, proteins and metabolites in response to cold stress have been reported. Recent studies demonstrate that post-transcriptional and post-translational regulations play a role in the regulation of cold signaling. In this review article, recent advances in cold stress signaling and tolerance are highlighted.

Miura, Kenji; Furumoto, Tsuyoshi

2013-01-01

203

Beam hardening and partial beam hardening of the bowtie filter: Effects on dosimetric applications in CT  

NASA Astrophysics Data System (ADS)

Purpose: To estimate the consequences on dosimetric applications when a CT bowtie filter is modeled by means of full beam hardening versus partial beam hardening. Method: A model of source and filtration for a CT scanner as developed by Turner et. al. [1] was implemented. Specific exposures were measured with the stationary CT X-ray tube in order to assess the equivalent thickness of Al of the bowtie filter as a function of the fan angle. Using these thicknesses, the primary beam attenuation factors were calculated from the energy dependent photon mass attenuation coefficients and used to include beam hardening in the spectrum. This was compared to a potentially less computationally intensive approach, which accounts only partially for beam hardening, by giving the photon spectrum a global (energy independent) fan angle specific weighting factor. Percentage differences between the two methods were quantified by calculating the dose in air after passing several water equivalent thicknesses representative for patients having different BMI. Specifically, the maximum water equivalent thickness of the lateral and anterior-posterior dimension and of the corresponding (half) effective diameter were assessed. Results: The largest percentage differences were found for the thickest part of the bowtie filter and they increased with patient size. For a normal size patient they ranged from 5.5% at half effective diameter to 16.1% for the lateral dimension; for the most obese patient they ranged from 7.7% to 19.3%, respectively. For a complete simulation of one rotation of the x-ray tube, the proposed method was 12% faster than the complete simulation of the bowtie filter. Conclusion: The need for simulating the beam hardening of the bow tie filter in Monte Carlo platforms for CT dosimetry will depend on the required accuracy.

Lopez-Rendon, X.; Zhang, G.; Bosmans, H.; Oyen, R.; Zanca, F.

2014-03-01

204

CID25: radiation hardened color video camera  

NASA Astrophysics Data System (ADS)

The charge injection device, CID25, is presented. The CID25 is a color video imager. The imager is compliant with the NTSC interlaced TV standard. It has 484 by 710 displayable pixels and is capable of producing 30 frames-per-second color video. The CID25 is equipped with the preamplifier-per-pixel technology combined with parallel row processing to achieve high conversion gain and low noise bandwidth. The on-chip correlated double sampling circuitry serves to reduce the low frequency noise components. The CID25 is operated by a camera system consisting of two parts, the head assembly and the camera control unit (CCU). The head assembly and the CCU can be separated by up to 150 meter long cable. The CID25 imager and the head portion of the camera are radiation hardened. They can produce color video with insignificant SNR degradation out to at least 2.85 Mrad of total dose of Co 60 ?-radiation. This represents the first in industry radiation hardened color video system, based on a semiconductor photo-detector that has an adequate sensitivity for room light operation.

Baiko, D. A.; Bhaskaran, S. K.; Czebiniak, S. W.

2006-03-01

205

Enzyme immobilization in silica-hardened organogels.  

PubMed

In this study we describe a novel method for immobilizing enzymes in a solid nanocomposite matrix based on gelatin gels, which are subsequently hardened by in situ polymerization of tetraethoxysilane (TEOS). Chromobacterium viscosum lipase is taken as the example. This immobilization method possesses the advantages of enzyme entrapment in microemulsions, together with newly beneficial qualities, such as transparency, which permits direct spectroscopic investigation, and considerable mechanical stability in both aqueous and organic solvents, which results in the maintenance of enzymatic activity for several months. The first step is enzyme solubilization in AOT reverse micelles, followed by transformation of this solution into an organogel by the addition of gelatin. The enzyme-containing gel, is then hardened by the formation of silicate polymer. A glassy nanocomposite is obtained, which is optically transparent, so that the protein can be studied directly spectroscopically. Circular dichroic spectra of cytochrome-c are shown as an example. The nanocomposite material can be dried and ground, yielding a powder that is stable in both aqueous and organic solvents. After extensive washing with water, the enzyme-containing nanocomposite showed good activity in cyclohexane. The synthesis of water-insoluble fatty acid esters was carried out in this solvent with yields close to 90%. In this case, the enzyme preparations can be used over a period of several months without loss of activity or chemical yield. PMID:11114662

Schuleit, M; Luisi, P L

2001-01-20

206

Simultaneous Inhibition of Linolenic Acid Synthesis in Winter Wheat Roots and Frost Hardening by BASF 13-338, a Derivative of Pyridazinone.  

PubMed

Treatment of 12-day-old winter wheat (Triticum aestivum) plants with BASF 13-338 {4-chloro-5 (dimethylamino)-2-phenyl-3(2H)-pyridazinone} 36 hours before frost hardening simultaneously and completely inhibits accumulation of linolenic acid in the roots during the hardening period and the acquisition of frost resistance. Increased unsaturation of fatty acids is therefore probably an important part of the mechanism of cold adaptation in winter wheat.BASF 13-338 also prevents the increase in per cent dry weight in roots and shoots during hardening and causes a decrease in root lipid phosphorus and total fatty acids.The concurrent increase in linoleic acid and decrease in linolenic acid in the treated plants, while the level of the other fatty acids is but little affected, suggest that BASF 13-338 specifically inhibits linoleic acid desaturase. PMID:16660018

Willemot, C

1977-07-01

207

State of the Art of Laser Hardening and Cladding  

Microsoft Academic Search

In this paper an overview is given about laser surface modification processes, which are developed especially with the aim of hardness improvement for an enhanced fatigue and wear behaviour. The processes can be divided into such with and without filler material and in solid-state and melting processes. Actual work on shock hardening, transformation hardening, remelting, alloying and cladding is reviewed,

F. Vollertsen; K. Partes; J. Meijer; E. Beyer; F. Dausinger; A. Ostendorf; A. Otto

2005-01-01

208

Predictive modeling of laser hardening of AISI5150H steels  

Microsoft Academic Search

This paper presents accurate predictive modeling of the laser hardening process in terms of laser operating parameters and initial microstructure without the need of any experimental data. The model provides the diagrams that are useful for predicting hardness profiles, optimizing practical process parameters and assessing the potential of laser hardening for different steels. It is shown that the hardness and

Rahul Patwa; Yung C. Shin

2007-01-01

209

Combined hardening of steel by concentrated energy fluxes  

Microsoft Academic Search

1 The existing techniques for processing the surface of the machine parts with concentrated energy fluxes (CEFs) differ with regard to the physical and chemical nature of the hardening action, the field of application, the technical characteristics, and their effectiveness. In some cases the field of application of the effective hardening processes is significantly limited. Then the required state of

A. V. Brover

2007-01-01

210

Impact of laser beam profiles in transformation hardening processing  

Microsoft Academic Search

The performance of a high power laser in material processing is strongly dependent on the laser beam intensity distribution. In particular, the uniformity of the beam intensity during laser transformation hardening is a critical factor in the success of the process. The results of tests on a new class of beam-integrating infrared optics used in the transformation hardening process are

Lidia Ferravante; Giovanni P. Mor; Laura Serri; Frank B. Foote

1993-01-01

211

Contamination Hardening of SU-31 and FS-85 Columbium Alloys.  

National Technical Information Service (NTIS)

A study has been made of the contamination hardening of SU-31 and FS-85 columbium alloys which results when samples are exposed in air temperatures of 1400 to 2600 F. Diffusion coefficients for the principal contaminant, calculated from hardening profiles...

R. B. Herring

1973-01-01

212

A beam hardening correction method based on HL consistency  

Microsoft Academic Search

XCT with polychromatic tube spectrum causes artifact called beam hardening effect. The current correction in CT device is carried by apriori polynomial from water phantom experiment. This paper proposes a new beam hardening correction algorithm that the correction polynomial depends on the relativity of projection data in angles, which obeys Helgasson-Ludwig Consistency (HL Consistency). Firstly, a bi-polynomial is constructed to

Xuanqin Mou; Shaojie Tang; Hengyong Yu

2006-01-01

213

Continuous monitoring of setting and hardening of mortar and concrete  

Microsoft Academic Search

Two main properties of cementitious mortar and concrete are most important, i.e. rheology and setting and hardening. Rheology determines workability and compaction ability. Setting determines the end of workability and hardening is responsible for strength gain and stiffness development. Rheology and setting are measured in practice by rather conventional methods, which do not lead to a continuous monitoring of properties

H. W. Reinhardt; C. U. Grosse

2004-01-01

214

Determination of the hardening temperature using a pulsed laser  

Microsoft Academic Search

A simple method is reported for determining the hardening temperature of a metal by measuring the depths of hardening at different intensities of a pulsed ruby laser. The value of 834 °C obtained for S45C steel agrees well with the reported value of 850 °C.

P. W. Chan; Y. W. Chan; F. K. Hui; H. S. Ng

1978-01-01

215

Radiation-Hardened Electronics for Space Environments (RHESE)  

NASA Technical Reports Server (NTRS)

This conference poster explores NASA's Radiation-Hardened Electronics for Space Environments project. This project aims to advance the state of the art in high performance, radiation-hardened electronics that enable the long-term, reliable operation of a spacecraft in extreme radiation and temperature of space and the lunar surface.

Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael; Cressler, John D.

2008-01-01

216

[Hardening of dental tissue by CO2 laser radiation].  

PubMed

A study was conducted to test the effects of CO2 laser irradiation on dental tissue. It was found that hardening of the dental tissue occurs. This was observed qualitatively by direct observation and by X-ray radiography. The hardening produced was also quantitatively measured using a hardness-meter on Rockwell scale. PMID:2634846

Aboites, V; Díaz, O; Cuevas, F

1989-03-01

217

A review of the stages of work hardening  

SciTech Connect

Stages of work hardening are reviewed with emphasis on links between each stage. Simple quantitative descriptions are given for each stage. Similarities between stage I, easy glide, and stage IV, large strain hardening, are pointed out both in terms of magnitude of the hardening rate and of the underlying mechanism of dislocation debris accumulation. Stage II is described as an athermal hardening stage that occurs when statistical variations in the dislocation ``forest`` lead to geometrical storage of dislocations. The steadily decreasing hardening rate observed in stage III is characterized by the increasing rate of loss of dislocation density due to dynamic recovery. Stage III appears to have an asymptote to a saturation stress which is determined by the characteristics of the dislocation tangles, or cell walls. The imperfect nature of the dynamic recovery process, however, leads to the accumulation of dislocation debris and this, by analogy with stage 1, causes the apparent saturation stress to rise, thus causing stage IV.

Rollett, A.D.; Kocks, U.F.

1993-07-01

218

Effect of crystallographic texture and dislocation hardening on limit strain in sheet metal forming  

NASA Astrophysics Data System (ADS)

In the metal industry, sheet metals are widely used to produce packaging materials for consumer goods, for structures such as automobilse, and for building construction and transportation. The desired shape of the products is imparted by plastic deformation in either the cold or hot state. Traditionally, the prediction of the forming limit of sheet metals is based on tensile tests, simulation tests and continuum mathematical models. Continuum models used in the prediction of the plastic behavior of sheet metals are based on average values of mechanical properties such as elongation, yield strength, work hardening and work-hardening rate, which are usually derived from tensile tests. Although attempts have been made to abandon the phenomenological description of the yield function by applying the theory of crystal plasticity to calculate the yield surface of texture polycrystals and hence the limit strains, only the average properties of the microstructure (e.g., the crystallographic texture of the bulk sheet) have been taken into account. So far, there has been no model for the prediction of the strain path and the limit strain of sheet metals that takes into account the effect of individual grain orientation and the dislocation property. In this thesis, different approaches in the study of plastic deformation are reviewed from the view-point of both macroplasticity and microplasticity. Instead of relying on a unique flow rule to describe the stress and strain relationship, the role of work hardening in the instability process of sheet metal and hence the flow localization phenomenon is explored from a study of the changes in the orientation of the constituent crystallites and from the changes in the dislocation density associated with different grain orientations during the course of large biaxial deformation. The changes in the crystallographic textures of an aluminium sheet sample deformed under various stress states from plane-strain tension to equi-biaxial tension have been followed. From X-ray diffraction and ODF(orientation distribution function) data, the orientation hardening characteristics as well as the dislocation hardening characteristics of the sheet samples as well as the major texture components have also been determined. (Abstract shortened by UMI.)

Wen, Xiyu

2000-10-01

219

Ribosomal Changes during Induction of Cold Hardiness in Black Locust Seedlings 1  

PubMed Central

Protein synthesis has been implicated in the cold-hardening process. Ribosomes from cold hardy and nonhardy black locust (Robinia pseudoacacia L.) seedlings were compared to determine if cold acclimation is related to alteration of ribosomal structure. Ribosomal structure, as indicated by thermal melting profiles, appears to be altered during induction of hardiness. Two-dimensional polyacrylamide gel electrophoresis of ribosomal proteins indicates at least 17 proteins from hardy seedlings that are different from those of nonhardy seedlings. These different proteins may be partially responsible for the different thermal melting profiles observed. Images

Bixby, James A.; Brown, Gregory N.

1975-01-01

220

Review of 'cold fusion'.  

National Technical Information Service (NTIS)

This review describes the results from the following works: (1) to overview the chronological history of 'cold fusion' including the International Conferences on cold fusion (ICCF-3 and ICCF-4), (2) to overview the various theories which can explain the '...

1995-01-01

221

Exercising in Cold Weather  

MedlinePLUS

... to cold can cause health problems such as hypothermia, a dangerous drop in body temperature. If you ... hat, scarf, and gloves. Know the signs of hypothermia: l Watch for signs of hypothermia: cold feet ...

222

The effect of cold spray impact velocity on deposit hardness  

NASA Astrophysics Data System (ADS)

The deposition and consolidation of metal powders by means of cold spray is a method where powder particles are accelerated to high velocity through entrainment in a gas undergoing expansion in a de Laval nozzle and are subsequently impacted upon a surface. The impacted powder particles form a consolidated structure which can be several centimeters thick. The characteristics of this structure depend on the initial characteristics of the metal powder and upon impact velocity. Initially soft particles are strain hardened during impact, resulting in a structure that can have a hardness value greater than that which can be achieved by conventional cold working. A materials model is proposed for these phenomena, and model calculation is compared with experimental data from cold sprayed copper and aluminum.

Champagne, Victor K.; Helfritch, Dennis J.; Trexler, Matthew D.; Gabriel, Brian M.

2010-09-01

223

Induction Hardening 5150 Steel: Effects of Initial Microstructure and Heating Rate  

NASA Astrophysics Data System (ADS)

Induction heating has permitted great progress in the surface hardening of a wide variety of steels, but results in a wide range of local thermal cycles. The metallurgical changes during rapid heating and cooling have not been sufficiently studied with respect to heating rate and prior microstructure. In the present investigation, induction dilatometry was performed on 5150 steel with ferrite-pearlite and tempered martensite initial microstructures to assess effects of experimentally controlled prior microstructure and heating rate on austenitization kinetics. Heating rates were varied from 0.3 to 300 °C/s to simulate industrial processes, and post-hardening metallography and hardness testing were performed. Results show that the transformation kinetics for prior ferrite-pearlite microstructures are significantly slower than for prior tempered martensite microstructures, although hardness is equivalent for a given thermal cycle. Metallographic evidence suggests significant remnant segregation of chromium in regions of pearlitic cementite (enriched); evidence of segregation was not observed metallographically for prior tempered martensite. Diffusion-based transformation simulations support observed ferrite-pearlite alloy segregation, suggest residual alloy segregation is possible for prior tempered martensite, and can be used to tailor austenitization thermal cycles to process requirements. Detailed time and temperature-dependent local microstructure development results from this study are directly applicable to practical induction hardening simulations.

Clarke, K. D.; van Tyne, C. J.; Vigil, C. J.; Hackenberg, R. E.

2011-03-01

224

On the precipitation-hardening behavior of the Al-Mg-Si-Cu alloy AA6111  

NASA Astrophysics Data System (ADS)

The precipitation-hardening behavior of aluminum alloy AA6111 during artificial aging and the influence of prior natural aging on the aging behavior were investigated. The evolution of microstructure was studied using quantitative transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The evolution of the relative volume fraction of precipitates for the solution-treated alloy was determined using isothermal calorimetry and a new analysis based on the DSC technique. Quantitative TEM was also used to obtain the rate of precipitation of microscopically resolvable phases during aging at 180 °C. Three types of precipitates, i.e., unresolved Guinier-Preston (GP) zones, ??, and Q', were found to form during aging at 180 °C. The evolution of yield strength was related to the evolution of microstructure. It was found that the high hardening rate during artificial aging for the solution-treated alloy is due to the rapid precipitation of the ?? phase. Natural aging prior to artificial aging was found to decrease the rate of precipitation of ??. The slow hardening rate for the naturally aged alloy was attributed to the slower nucleation and growth of ?? phase.

Esmaeili, S.; Wang, X.; Lloyd, D. J.; Poole, W. J.

2003-03-01

225

Design Features and Initial RF Performance of a Gradient Hardened 17 GHz TW Linac Structure  

NASA Astrophysics Data System (ADS)

To avoid surface erosion damage and to assist in studying RF breakdown thresholds in 17 GHz TW linac structures, a gradient hardened structure has been fabricated with high temperature brazed and machined stainless steel surfaces located in the peak E-field region of the beam apertures and the peak H-field regions of the input coupler cavity. The microwave design parameters and physical dimensions of this 22 cavity, 120 degree phase advance structure were chosen to allow the high gradient performance to be compared against a similar design all-copper structure that has been tested in a dual ring, power recirculating amplifier system. The final design parameters of the gradient hardened structure are discussed; the influence of stainless steel RF losses on the power buildup of the resonant ring and on the structure gradient distribution are described; waveforms are shown of the unique ability of the power amplifier to rapidly quench RF breakdown discharges in the linac structure by automatically sensing and redirecting the RF source power to a matched load; and preliminary test results during high power RF processing of the gradient hardened linac structure are presented.

Haimson, J.; Mecklenburg, B.

2009-01-01

226

Jerky loads on surface-hardened gears  

NASA Technical Reports Server (NTRS)

Damage occurs again and again in practice in the form of transmissions with surface hardened gears which break after a very long operating time (explained by seldom occurring jerky loads). Gear drives are frequently exposed to jerky stresses which are greater than their fatigue limit. These stresses are considered in gear calculations, first, by shock factors when the transmission is to be designed as high endurance with regard to overloads and, second, in the form of operating ratios when the design is to be time enduring with regard to overloads. The size of the operating ratio depends not only on torque characteristics, drive and processing machine, but also on the material and heat treatment.

Rettig, H.; Wirth, X.

1978-01-01

227

Novel SEU hardened PD SOI SRAM cell  

NASA Astrophysics Data System (ADS)

A novel SEU hardened 10T PD SOI SRAM cell is proposed. By dividing each pull-up and pull-down transistor in the cross-coupled inverters into two cascaded transistors, this cell suppresses the parasitic BJT and source-drain penetration charge collection effect in PD SOI transistor which causes the SEU in PD SOI SRAM. Mixed-mode simulation shows that this novel cell completely solves the SEU, where the ion affects the single transistor. Through analysis of the upset mechanism of this novel cell, SEU performance is roughly equal to the multiple-cell upset performance of a normal 6T SOI SRAM and it is thought that the SEU performance is 17 times greater than traditional 6T SRAM in 45nm PD SOI technology node based on the tested data of the references. To achieve this, the new cell adds four transistors and has a 43.4% area overhead and performance penalty.

Chengmin, Xie; Zhongfang, Wang; Xihu, Wang; Longsheng, Wu; Youbao, Liu

2011-11-01

228

Cold dark matter heats up.  

PubMed

A principal discovery in modern cosmology is that standard model particles comprise only 5 per cent of the mass-energy budget of the Universe. In the ?CDM paradigm, the remaining 95 per cent consists of dark energy (?) and cold dark matter. ?CDM is being challenged by its apparent inability to explain the low-density 'cores' of dark matter measured at the centre of galaxies, where centrally concentrated high-density 'cusps' were predicted. But before drawing conclusions, it is necessary to include the effect of gas and stars, historically seen as passive components of galaxies. We now understand that these can inject heat energy into the cold dark matter through a coupling based on rapid gravitational potential fluctuations, explaining the observed low central densities. PMID:24522596

Pontzen, Andrew; Governato, Fabio

2014-02-13

229

Cough and Cold Medicine Abuse  

MedlinePLUS

... and Cold Medicine Abuse DrugFacts: Cough and Cold Medicine Abuse Email Facebook Twitter Revised May 2014 Some ... diverted for abuse. How Are Cough and Cold Medicines Abused? Cough and cold medicines are usually consumed ...

230

Hypothermia: A Cold Weather Hazard  

MedlinePLUS

... cold air. But, not everyone knows that cold weather can also lower the temperature inside your body. ... cold it is where you are. Check the weather forecasts for windy and cold weather. Try to ...

231

RAPID Contacts  

Cancer.gov

Rapid Access to Preventive Intervention Development (RAPID) Program Contacts Program Contact RAPID ProgramAttn: Izet M. Kapetanovic, PhD, Program Director Chemopreventive Agent Development Research Group Division of Cancer Prevention, NCI Executive Plaza

232

An extended crystal plasticity model for latent hardening in polycrystals  

NASA Astrophysics Data System (ADS)

In this contribution, a computational approach to modeling size-dependent self- and latent hardening in polycrystals is presented. Latent hardening is the hardening of inactive slip systems due to active slip systems. We focus attention on the investigation of glide system interaction, latent hardening and excess dislocation development. In particular, latent hardening results in a transition to patchy slip as a first indication and expression of the development of dislocation microstructures. To this end, following Nye (Acta Metall 1:153-162, 1953), Kondo (in Proceedings of the second Japan national congress for applied mechanics. Science Council of Japan, Tokyo, pp. 41-47, 1953), and many others, local deformation incompatibility in the material is adopted as a measure of the density of geometrically necessary dislocations. Their development results in additional energy being stored in the material, leading to additional kinematic-like hardening effects. A large-deformation model for latent hardening is introduced. This approach is based on direct exploitation of the dissipation principle to derive all field relations and (sufficient) forms of the constitutive relations as based on the free energy density and dissipation potential. The numerical implementation is done via a dual-mixed finite element method. A numerical example for polycrystals is presented.

Bargmann, Swantje; Svendsen, Bob; Ekh, Magnus

2011-12-01

233

Porosity and mechanically optimized PLGA based in situ hardening systems.  

PubMed

Goal of the present study was to develop and to characterize in situ-hardening, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (?-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding hardened implants were investigated. We proved cell-compatibility by live/dead assays for the hardened porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture hardened scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the ?-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the hardened scaffolds. Consequently, we consider the in situ hardening system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the hardened implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity. PMID:22947486

Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W

2012-11-01

234

Magnetic hysteresis behavior and microstructure of severely cold-worked and aged Co-Fe-Nb alloy  

Microsoft Academic Search

The magnetic hysteresis behavior of severely cold-worked and aged 85Co-12Fe-3Nb alloy was studied in relation to the microstructure. Magnetic hardening of the alloy can be attributed to the pinning of the domain wall by quasispherical Co3Nb precipitates. Alloys cold worked to 97.8% reduction in area and aged at 700, 800, and 900 °C showed the hysteresis behavior characteristic of inhomogeneous

Yuichi Suzuki; Masato Sagawa; Masanori Okada; Zenzo Henmi

1979-01-01

235

On the effects of predeformation on work hardening of ultra-low-carbon sheet steel  

NASA Astrophysics Data System (ADS)

Predeformation affects the work-hardening behavior of sheet metals in sequential forming operations by producing various strain histories in different parts of the sheet. Several investigators have reported the effects of two-stage deformation on the behavior of sheet metals, particularly justification has been presented on face-centered cubic (fcc) alloys. However, the works on low-carbon ferritic steels are not conclusive. This article reports some new findings of the effects of two modes of predeformation on the subsequent stress-strain relationship in ultra-low-carbon sheet steels. The details of a laboratory test system are presented along with methods used to reduce the data. The effect of the stability ratio, a measure of the degree to which the interstitial atoms are free, on the hardening rate at second-stage of deformation was studied. For stabilized sheet steels, it was found that changes in strain path from equibiaxial stretching to uniaxial tension cause an increase in the flow stress relative to the flow stress at similar effective strain in continued monotonic. For unstabilized sheet steels, a significant increase in the flow stress was not observed with either equibiaxial prestraining or cold rolling and equibiaxial stretching.

Mirshams, R. A.; Mohamadian, H. P.; Crosby, K. E.

1994-02-01

236

Fructan metabolism and expression of genes coding fructan metabolic enzymes during cold acclimation and overwintering in timothy (Phleum pratense).  

PubMed

Metabolism of fructans in temperate grasses dynamically fluctuates before and during winter and is involved in the overwintering activity of plants. We monitored three candidate factors that may be involved in seasonal fructan metabolism in timothy (Phleum pratense): transcription levels of two fructosyltransferase (PpFT1 and PpFT2) genes and one fructan exohydrolase (Pp6-FEH1) gene during fall and winter and under artificially cold conditions. Functional analysis using a recombinant enzyme for PpFT2, a novel fructosyltransferase cDNA, revealed that it encoded sucrose:fructan 6-fructosyltransferase, with enzymatic properties different from previously characterized PpFT1. PpFT1 transcripts decreased from September to December as the amount of fructans increased, whereas PpFT2 transcripts increased in timothy crowns. PpFT2 was transcriptionally more induced than PpFT1 in response to cold and sucrose in timothy seedlings. A rapid increase in Pp6-FEH1 transcripts and increased monosaccharide content were observed in timothy crowns when air temperature was continuously below 0°C and plants were not covered by snow. Transcriptional induction of Pp6-FEH1 by exposure to -3°C was also observed in seedlings. These findings suggest Pp6-FEH1 involvement in the second phase of hardening. PpFT1 and PpFT2 transcription levels decreased under snow cover, whereas Pp6-FEH1 transcription levels were constant, which corresponded with the fluctuation of fructosyltransferase and fructan exohydrolase activities. Inoculation with snow mold fungi (Typhula ishikariensis) increased Pp6-FEH1 transcription levels and accelerated hydrolysis of fructans. These results suggest that transcriptional regulation of genes coding fructan metabolizing enzymes is partially involved in the fluctuation of fructan metabolism during cold acclimation and overwintering. PMID:24913052

Tamura, Ken-Ichi; Sanada, Yasuharu; Tase, Kazuhiro; Yoshida, Midori

2014-07-01

237

Radiation Hardened by Design CMOS ASIC for Thermopile Readouts.  

National Technical Information Service (NTIS)

A radiation hardened by design (RHBD) mixed-signal application specific integrated circuit (ASIC) has been designed for a thermopile readout for operation in the harsh Jovian orbital environment. The multi-channel digitizer (MCD) ASIC includes 18 low nois...

G. Quilligan J. DuMonthier S. Aslam

2012-01-01

238

Positron annihilation study on age-hardened Al alloys.  

National Technical Information Service (NTIS)

Positron annihilation measurements are used to characterize the precipitation phenomena during the age hardening process of the 7012, 2219 and 2014 Al alloys. The response of the positron annihilation parameters during the ageing process can be explained ...

P. Bartolomei M. Biasini M. Valli S. Abis A. Dupasquier

1991-01-01

239

Stress corrosion cracking evaluation of precipitation-hardening stainless steel  

NASA Technical Reports Server (NTRS)

Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

Humphries, T. S.; Nelson, E. E.

1970-01-01

240

Deformation Processing of Precipitation-Hardenable Stainless Steels.  

National Technical Information Service (NTIS)

The report covers the state of the art of both primary and secondary fabrication methods for the precipitation-hardenable stainless steels. Methods currently employed for primary fabrication of these alloys include rolling, extrusion, forging, and drawing...

A. F. Gerds D. E. Strohecker F. W. Boulger

1965-01-01

241

Stimulation of Phospholipid Biosynthesis during Frost Hardening of Winter Wheat.  

PubMed

Lipids were labeled with (33)P during frost hardening of two varieties of winter wheat (Triticum aestivum), hardy Kharkov and much less hardy Champlein. The main labeled compounds were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylglycerol. With time of incorporation the proportion of the radioactivity incorporated into the lipids increased in phosphatidylcholine, especially in Kharkov and at 1 C. During hardening, phospholipid synthesis was greatly stimulated in Kharkov, but much less in Champlein. The proportion of the phospholipids synthesized changed only little with hardening, with a trend towards an increase in phosphatidylcholine. Increased phospholipid synthesis does not seem to be a prerequisite to hardening in winter wheat. However, a high rate of phospholipid synthesis may be required to maintain frost resistance. PMID:16659082

Willemot, C

1975-02-01

242

Beam Hardening Corrections in Quantitative Computed Tomography  

SciTech Connect

Volumetric computed tomography (VCT) is the emerging 3D NDE inspection technique that gives highest throughput and better image quality. Industrial components in general demands higher x-ray energy for inspection for which polychromatic x-ray sources are used in common. Polychromatic nature of the x-rays gives rise to non-linear effects in the VCT projection data measurements called to be the beam hardening (BH) effects. BH produces prominent artifacts in the reconstructed images thereby deteriorating the image quality. Quantitative analysis such as density quantification, dimensional analysis etc., becomes difficult with the presence of these artifacts. This paper describes the BH correction using preprocessing technique for the homogeneous materials. Selection of effective energy at which the monoenergetic linear attenuation coefficient of a particular material equals to that of the polyenergetic beam is critical for BH correction. Various methods to determine the effective energy and their consequence in the quantitative measurements have been investigated in the present study. In this paper, BH corrections for heterogeneous materials have also been explored.

Vedula, Venumadhav; Venugopal, Manoharan; Raghu, C.; Pandey, Pramod [John F. Welch Technology Centre, GE Global Research Centre, Bangalore, (India)

2007-03-21

243

Mechanical properties of zona pellucida hardening.  

PubMed

We have investigated the changes in the mechanical properties of the zona pellucida (ZP), a multilayer glycoprotein coat that surrounds mammalian eggs, that occur after the maturation and fertilization process of the bovine oocyte by using atomic force spectroscopy. The response of the ZP to mechanical stress has been recovered according to a modified Hertz model. ZP of immature oocytes shows a pure elastic behavior. However, for ZPs of matured and fertilized oocyte, a transition from a purely elastic behavior, which occurs when low stress forces are applied, towards a plastic behavior has been observed. The high critical force necessary to induce deformations, which supports the noncovalent long interaction lifetimes of polymers, increases after the cortical reaction. Atomic force microscopy (AFM) images show that oocyte ZP surface appears to be composed mainly of a dense, random meshwork of nonuniformly arranged fibril bundles. More wrinkled surface characterizes matured oocytes compared with immature and fertilized oocytes. From a mechanical point of view, the transition of the matured ZP membrane toward fertilized ZP, through the hardening process, consists of the recovery of the elasticity of the immature ZP while maintaining a plastic transition that, however, occurs with a much higher force compared with that required in matured ZP. PMID:19471918

Papi, Massimiliano; Brunelli, Roberto; Sylla, Lakamy; Parasassi, Tiziana; Monaci, Maurizio; Maulucci, Giuseppe; Missori, Mauro; Arcovito, Giuseppe; Ursini, Fulvio; De Spirito, Marco

2010-05-01

244

Cylindrical shell buckling through strain hardening  

SciTech Connect

Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.

Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Gupta, D. [USDOE, Germantown, MD (United States)

1995-04-01

245

Laser-ultrasonic hardening of the surface of steel  

SciTech Connect

An investigation was made of the feasibility of laser-ultrasonic hardening of the surface of steel with a controlled change in the structurally stressed state of the surface layer. The advantages of the laser-ultrasonic treatment were demonstrated by the formation of harder and deeper surface hardening zones with simultaneous control of their structure and phase composition and of the formation of residual stresses. (interaction of laser radiation with matter. laser plasma)

Gureev, D M [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

1998-03-31

246

Laser surface hardening of ductile cast iron for vehicle die  

Microsoft Academic Search

Experiments of laser transformation hardening were performed with various process parameters on the surface of ductile cast iron block, which is often used for vehicle body. The distribution of microhardness along the case depth direction and the variation of microstructure of hardened track were investigated. Wear test was carried out using a ball-on-flat-type wear-test machine. The results indicate that the

Yanghui Xu; Jichang Liu

2010-01-01

247

Hydrogen embrittlement susceptibility of laser-hardened 4140 steel  

Microsoft Academic Search

Slow strain rate tensile (SSRT) tests were performed to investigate the susceptibility to hydrogen embrittlement of laser-hardened AISI 4140 specimens in air, gaseous hydrogen and saturated H2S solution. Experimental results indicated that round bar specimens with two parallel hardened bands on opposite sides along the loading axis (i.e. the PH specimens), exhibited a huge reduction in tensile ductility for all

L. W Tsay; Z. W Lin; R. K Shiue; C Chen

2000-01-01

248

Strain hardening of fcc metal surfaces induced by microploughing  

SciTech Connect

Microploughing experiments were used as a method for better understanding the ploughing mechanism in gold and iridium single crystals. The plough depths ranged from 20 nm in iridium to 1,600 nm in gold. Yield stress profiles and TEM analyses indicate that both materials strain harden even when very small volumes of material are involved. Strain hardening theory, as applied to bulk material, is useful in analyzing the results.

Day, R.D.; Dickerson, R.M. [Los Alamos National Lab., NM (United States); Russell, P.E. [North Carolina State Univ., Raleigh, NC (United States)

1998-12-01

249

Phase conversions and radiation hardening in irradiated chromium steels  

Microsoft Academic Search

It is a well-known fact [i] that chromium steels of the ferritic and ferritic-martensitic classes do not experience extensive radiation-induced swelling and can be considered promising materials for the core of fast reactors. But since radiation hardening and embrittlement are a serious problem in these steels, the physics of the processes resulting in the hardening must be studied to obtain

V. S. Khmelevskaya; A. G. Ioltukhovskii; V. G. Malynkin; M. V. Leont'eva-Smirnova; S. P. Solov'ev

1987-01-01

250

Forming limit of sheet metals based on mixed hardening model  

Microsoft Academic Search

The calculation method of forming limit of sheet metals based on M-K instability theory is proposed, and the method is applicable\\u000a to different yield criterions and hardening models. The forming limit diagrams of AA5754-O, AA6111-T4 aluminum alloy sheet\\u000a and DP steel sheet under combined loading paths are obtained based on mixed hardening model with YLD2000-2D yield criterion\\u000a proposed by Barlat

HaiBo Wang; Min Wan

2009-01-01

251

Measurement and analysis of plane-strain work hardening  

Microsoft Academic Search

A new technique for measurement of plane-strain work hardening has been developed which uses tensile loading and computer analysis for interpretation, and which eliminates the experimental uncertainties of large strain gradients, friction, and out-of-plane bending inherent in the usual plane-strain deformation modes. Plane-strain and tensile work-hardening curves have been measured for 2036-T4 aluminum alloy using several types of sheet specimens.

R. H. Wagoner

1980-01-01

252

Surface induction hardening of Minsk Automobile Plant truck final gears  

Microsoft Academic Search

Conclusions Continuous induction hardening of gears with movement of their tooth surface with a varied rate relative to the inductor, which is located parallel to the generatrix, makes it possible to provide a uniform hardened case depth on the contour of the tooth surface of 1.0–2.2 mm and a high surface hardness of 56–62 HRCeq for 40, 40Kh, and 30KhGSA

P. S. Gurchenko; V. M. Bykov; Yu. I. Shumakov

1990-01-01

253

Finite deformation plasticity and viscoplasticity laws exhibiting nonlinear hardening rules  

Microsoft Academic Search

This paper deals with plasticity and viscoplasticity laws exhibiting nonlinear kinematic hardening as well as nonlinear isotropic\\u000a hardening rules. In Tsakmakis (1996a, b) a constitutive theory has been formulated within the framework of finite deformations,\\u000a which is based on the concept of so-called dual variables and associated time derivatives. Within two families of dual variables,\\u000a two different formulations have been

E. Diegele; W. Jansohn; Ch. Tsakmakis

2000-01-01

254

Utilisation of sinter-hardening treatment for various sintered steels  

Microsoft Academic Search

Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development of sinter-hardening process applied to different steels including pre-alloyed Ni-Mo steels with W addition, Astaloy CrM and experimental sintered duplex stainless steels. The mechanical properties, focusing in particular on hardness and wear resistance, of two different sinter-hardened steels were described. Microstructure characteristic of produced

L. A. Dobrza?ski a; J. Otr?ba; Z. Brytan; M. Rosso

255

On the stability of elastic–plastic systems with hardening  

Microsoft Academic Search

This paper discusses the stability of quasi-static paths for a continuous elastic–plastic system with hardening in a one-dimensional (bar) domain. Mathematical formulations, as well as existence and uniqueness results for dynamic and quasi-static problems involving elastic–plastic systems with linear kinematic hardening are recalled in the paper. The concept of stability of quasi-static paths used here is essentially a continuity property

J. A. C. Martins; M. D. P. Monteiro Marques; A. Petrov

2008-01-01

256

On the stability of elastic-plastic systems with hardening  

Microsoft Academic Search

This paper discusses the stability of quasi-static paths for a continuous elastic-plastic system with hardening in a one-dimensional (bar) domain. Mathematical formulations, as well as existence and uniqueness results for dynamic and quasi-static problems involving elastic-plastic systems with linear kinematic hardening are recalled in the paper. The concept of stability of quasi-static paths used here is essentially a continuity property

J. A. C. Martins; M. D. P. Monteiro Marques; A. Petrov

2008-01-01

257

A mathematical model of the vibrational impact hardening of parts  

NASA Astrophysics Data System (ADS)

A mathematical model is proposed which describes the vibrational impact hardening of parts by a free working medium. The working medium is modeled by a set of infinitely thin rigid plates with elastic-plastic and viscous coupling between them. A method for optimizing the hardening process is described. Results obtained for a compressor blade of KhN70MVTYuB alloy are presented as an example.

Khalimulin, R. M.

258

Cold nuclear matter effects on J/? yields as a function of rapidity and nuclear geometry in d+A collisions at sqrt[s(NN)]=200??GeV.  

PubMed

We present measurements of J/? yields in d+Au collisions at sqrt[s(NN)]=200??GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/? rapidity (-2.2rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state. PMID:22107186

Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Angerami, A; Aoki, K; Apadula, N; Aphecetche, L; Aramaki, Y; Asai, J; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Basye, A T; Bathe, S; Batsouli, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bhom, J H; Bickley, A A; Blau, D S; Boissevain, J G; Bok, J S; Borel, H; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Caringi, A; Chang, B S; Chang, W C; Charvet, J-L; Chen, C-H; Chernichenko, S; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Churyn, A; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa del Valle, Z; Connors, M; Constantin, P; Csanád, M; Csörgo, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Dubey, A K; Durham, J M; Durum, A; Dutta, D; Dzhordzhadze, V; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Eyser, K O; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Ĺ; Hadj Henni, A; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haruna, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E J; Kim, S H; Kim, Y-J; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Klay, J; Klein-Boesing, C; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Layton, D; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, T; Leitch, M J; Leite, M A L; Lenzi, B; Li, X; Lichtenwalner, P; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Mašek, L; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; Means, N; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Mukhopadhyay, D; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Niita, T; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ruži?ka, P; Rykov, V L; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Semenov, V; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slune?ka, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomita, Y; Torii, H; Towell, R S

2011-09-30

259

Cold Nuclear Matter Effects on J/{psi} Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at {radical}(s{sub NN})=200 GeV  

SciTech Connect

We present measurements of J/{psi} yields in d+Au collisions at {radical}(s{sub NN})=200 GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/{psi} rapidity (-2.2rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

Adare, A.; Bickley, A. A.; Ellinghaus, F.; Kinney, E.; Kiriluk, K.; Linden Levy, L. A.; Nagle, J. L.; Rosen, C. A.; Seele, J.; Wysocki, M. [University of Colorado, Boulder, Colorado 80309 (United States); Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Aidala, C.; Datta, A. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337 (United States); Ajitanand, N. N. [Chemistry Department, Stony Brook University, SUNY, Stony Brook, New York 11794-3400 (United States)

2011-09-30

260

Cold Nuclear Matter Effects on J\\/psi Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at sNN=200GeV  

Microsoft Academic Search

We present measurements of J\\/psi yields in d+Au collisions at sNN=200GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J\\/psi rapidity (-2.2

A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; A. Angerami; K. Aoki; N. Apadula; L. Aphecetche; Y. Aramaki; J. Asai; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; A. Baldisseri; K. N. Barish; P. D. Barnes; B. Bassalleck; A. T. Basye; S. Bathe; S. Batsouli; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; J. H. Bhom; A. A. Bickley; D. S. Blau; J. G. Boissevain; J. S. Bok; H. Borel; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; A. Caringi; B. S. Chang; W. C. Chang; J.-L. Charvet; C.-H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; A. Churyn; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa Del Valle; M. Connors; P. Constantin; M. Csanád; T. Csörgo; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; D. D'Enterria; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; A. K. Dubey; J. M. Durham; A. Durum; D. Dutta; V. Dzhordzhadze; L. D'Orazio; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'Yo; S. Esumi; K. O. Eyser; B. Fadem; D. E. Fields; M. Finger; M. Finger Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; J. Gosset; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; H.-Ĺ. Gustafsson; A. Hadj Henni; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; E. P. Hartouni; K. Haruna; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; J. Imrek; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; Y. Iwanaga; B. V. Jacak; J. Jia; X. Jiang; J. Jin; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. H. Kim; D. J. Kim; E. Kim; S. H. Kim; Y.-J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; J. Klay; C. Klein-Boesing; L. Kochenda; B. Komkov; M. Konno; J. Koster; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; M. J. Kweon; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; D. Layton; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; T. Lee; M. J. Leitch; M. A. L. Leite; B. Lenzi; X. Li; P. Lichtenwalner; P. Liebing; L. A. Linden Levy; T. Liska; A. Litvinenko; H. Liu; M. X. Liu; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; L. Masek; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; N. Means; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; P. Mikes; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; D. P. Morrison; T. V. Moukhanova; D. Mukhopadhyay; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; T. Niita; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; A. P. T. Palounek; V. Pantuev; V. Papavassiliou; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J.-C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruzicka; V. L. Rykov; B. Sahlmueller; N. Saito; T. Sakaguchi; S. Sakai; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; V. Semenov; R. Seto; D. Sharma; I. Shein; T.-A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slunecka; A. Soldatov; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; F. Staley; P. W. Stankus; E. Stenlund; M. Stepanov; A. Ster; S. P. Stoll; T. Sugitate; C. Suire; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko

2011-01-01

261

Cold fusion: Alchemist's dream  

NASA Astrophysics Data System (ADS)

In this report the following topics relating to cold fusion are discussed: muon catalyzed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalyzed cold fusion; vibrational mechanisms in excited states of D2 molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D2 fusion at low energies; fusion of deuterons into He-4; secondary D+T fusion within the hydrogenated metal lattice; helium-3 to helium-4 ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of helium-3/helium-4.

Clayton, E. D.

1989-09-01

262

Forming limit stresses predicted by phenomenological plasticity theories with anisotropic work-hardening behavior  

Microsoft Academic Search

Forming limit stresses of sheet metals subjected to linear and combined stress paths are analyzed using the M-K model in conjunction with two anisotropic work-hardening models: a work-hardening model which is capable of describing Bauschinger and cross-hardening effects, and a work-hardening model which cannot predict the cross-hardening effect. It is found that the forming limit stress is path-independent when the

Kengo Yoshida; Noriyuki Suzuki

2008-01-01

263

Effect of heat treatment on strain hardening of ZK60 Mg alloy  

Microsoft Academic Search

Strain hardening behaviors of extruded ZK60 Mg alloy under different heat treatments (T4, T5 and T6) were studied using uniaxial tensile tests at room temperature. Hardening capacity, strain hardening exponent as well as strain hardening rate curve were obtained according to true plastic stress–strain curves. T5 and T6 treatments decrease strain hardening of extruded ZK60 alloy, and subsequently give rise

Xianhua Chen; Fusheng Pan; Jianjun Mao; Jingfeng Wang; Dingfei Zhang; Aitao Tang; Jian Peng

2011-01-01

264

Improved sperm cryopreservation using cold cryoprotectant.  

PubMed

It has generally been assumed that very rapid cooling above freezing point would be deleterious to human sperm because it would result in cold shock. Consequently, most routine cryopreservation protocols involve the use of warm (20-30 degrees C) cryoprotectant and slow cooling above the freezing point in order to minimise the risk of cold shock. In order to test this assumption, we added an equal volume of cold (4 degrees C) cryoprotectant in a single aliquot to warm (20, 30 or 37 degrees C) semen to induce rapid cooling. The results of this procedure were compared with those obtained using warm cryoprotectant or with the routine cryopreservation protocol used in this laboratory. The use of cold cryoprotectant resulted in a significant (P = 0.016) improvement (mean 63%, range 42%-79%) in post-thaw motility recovery compared with a standard procedure(mean 47%, range 35%-67%) and a significant (P = 0.016) improvement in post-thaw sperm velocity. A cold glycerol/egg yolk/citrate (GEYC) mixture also gave significantly higher motility recovery than GEYC equilibrated to either room temperature (20 degrees C) or body temperature (37 degrees C). Sperm frozen using the cold cryoprotectant protocol were as efficient at binding to and penetrating the human zona pellucida as sperm frozen with a standard protocol. The modified cryopreservation procedure may lead to improved pregnancy rates in donor insemination and in vitro fertilisation. Further investigation is required to determine how the cold cryoprotectant improves the cryopreservation outcome. PMID:14984694

Clarke, G N; Liu, D Y; Baker, H W G

2003-01-01

265

High-Performance, Radiation-Hardened Electronics for Space Environments  

NASA Technical Reports Server (NTRS)

The Radiation Hardened Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog Arrays (FPAA)s for use in reconfigurable architectures. As these component/chip level technologies mature, the RHESE project emphasis shifts to focus on efforts encompassing total processor hardening techniques and board-level electronic reconfiguration techniques featuring spare and interface modularity. This phased approach to distributing emphasis between technology developments provides hardened FPGA/FPAAs for early mission infusion, then migrates to hardened, board-level, high speed processors with associated memory elements and high density storage for the longer duration missions encountered for Lunar Outpost and Mars Exploration occurring later in the Constellation schedule.

Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.

2007-01-01

266

Cold Nuclear Matter Effects on J\\/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV  

Microsoft Academic Search

We present measurements of J\\/psi yields in d+Au collisions at sqrt(s_NN) =\\u000a200 GeV recorded by the PHENIX experiment and compare with yields in p+p\\u000acollisions at the same energy per nucleon-nucleon collision. The measurements\\u000acover a large kinematic range in J\\/psi rapidity (-2.2 < y < 2.4) with high\\u000astatistical precision and are compared with two theoretical models: one

A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; A. Angerami; K. Aoki; N. Apadula; L. Aphecetche; Y. Aramaki; J. Asai; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; A. Baldisseri; K. N. Barish; P. D. Barnes; B. Bassalleck; A. T. Basye; S. Batsouli; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; J. H. Bhom; A. A. Bickley; D. S. Blau; J. G. Boissevain; J. S. Bok; H. Borel; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; A. Caringi; B. S. Chang; W. C. Chang; J.-L. Charvet; C.-H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; A. Churyn; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; P. Constantin; M. Csanád; T. CsörgHo; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; D. d'Enterria; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; L. D Orazio; O. Drapier; A. Drees; K. A. Drees; A. K. Dubey; J. M. Durham; A. Durum; D. Dutta; V. Dzhordzhadze; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; K. O. Eyser; B. Fadem; D. E. Fields; M. Finger; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; J. Gosset; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; H.-Ĺ. Gustafsson; A. Hadj Henni; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; J. Hanks; R. Han; E. P. Hartouni; K. Haruna; E. Haslum; R. Hayano; M. Heffner; T. K. Hemmick; T. Hester; X. He; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; J. Imrek; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; Y. Iwanaga; B. V. Jacak J. Jia; X. Jiang; J. Jin; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. H. Kim; D. J. Kim; E. J. Kim; S. H. Kim; Y.-J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; J. Klay; C. Klein-Boesing; L. Kochenda; B. Komkov; M. Konno; J. Koster; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; M. J. Kweon; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; D. Layton; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; T. Lee; M. J. Leitch; M. A. L. Leite; B. Lenzi; P. Lichtenwalner; P. Liebing; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; X. Li; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; L. Mašek; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; N. Means; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; T. V. Moukhanova; D. Mukhopadhyay; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; T. Niita; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; K. Okada; M. Oka; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; A. P. T. Palounek; V. Pantuev; V. Papavassiliou; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J.-C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; V. L. Rykov; B. Sahlmueller; N. Saito; T. Sakaguchi; S. Sakai; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; V. Semenov; R. Seto; D. Sharma; I. Shein; T.-A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; A. Soldatov; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; F. Staley; P. W. Stankus; E. Stenlund; M. Stepanov; A. Ster; S. P. Stoll; T. Sugitate; C. Suire; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; P. Tarján; H. Themann; D. Thomas

2010-01-01

267

About RAPID  

Cancer.gov

The Rapid Access to Preventive Intervention Development (RAPID) Program makes the contract resources from NCI's Division of Cancer Prevention available to academic and academically-affiliated investigators for preclinical and early clinical drug development.

268

Process design of press hardening with gradient material property influence  

NASA Astrophysics Data System (ADS)

Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

2011-05-01

269

Process design of press hardening with gradient material property influence  

SciTech Connect

Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

Neugebauer, R. [Fraunhofer Institute for Machine Tools and Forming Technology IWU, Chemnitz (Germany); Professorship for Machine Tools and Forming Technology, TU Chemnitz (Germany); Schieck, F. [Fraunhofer Institute for Machine Tools and Forming Technology IWU, Chemnitz (Germany); Rautenstrauch, A. [Professorship for Machine Tools and Forming Technology, TU Chemnitz (Germany)

2011-05-04

270

Life stage-related differences in hardening and acclimation of thermal tolerance traits in the kelp fly, Paractora dreuxi (Diptera, Helcomyzidae).  

PubMed

It is widely appreciated that physiological tolerances differ between life stages. However, few studies have examined stage-related differences in acclimation and hardening. In addition, the behavioural responses involved in determining the form and extent of the short-term phenotypic response are rarely considered. Here, we investigate life stage differences in the acclimation and hardening responses of the survival of a standard heat shock (SHS) and standard low temperature (or cold) shock (SCS), and the crystallization temperature (or supercooling point, SCP) of adults and larvae of the sub-Antarctic kelp fly, Paractora dreuxi. These stages live in the same habitat, but differ substantially in their mobility and thus environmental temperatures experienced. Results showed that neither acclimation nor hardening affected the lower lethal limits in larvae or adults. Adults showed an increase in survival of upper lethal limits after low temperature acclimation, whilst larvae showed a consistent lack of response. The acclimationxhardening interaction significantly affected the SCP in adults, but no response to either acclimation or hardening was found in the larvae. This study further demonstrates the complexities of thermal tolerance responses in P. dreuxi. PMID:19171152

Marais, Elrike; Terblanche, John S; Chown, Steven L

2009-04-01

271

Analysis of cold and hot isostatic compaction of spherical particles  

SciTech Connect

Cold and hot isostatic compaction of monosized metal powders is analyzed within the framework of viscoplastic theory for particles packed both in a regular and a random manner. The problem of local contact between spherical particles is analyzed first by drawing upon recent detailed numerical studies of spherical indentation of power law plastic and creeping solids. The compaction process is then modelled as a self-similar contraction of unit (average) cells, in contrast to commonly used phenomenological assumptions, yielding a simple but rigorous relation between the densification density and center-to-center approach of adjacent powder particles. The resulting densification formulae are easy to apply and the influence of hardening and creep parameters appears in concise form. Predictions are compared with discriminating experimental data for a variety of different powder materials, both in the cold and a hot state, and the agreement is good for a relative density increase of up to 30%.

Larsson, P.L.; Biwa, S.; Storaakers, B. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid Mechanics] [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid Mechanics

1996-09-01

272

A dnaN Plasmid Shuffle Strain for Rapid In Vivo Analysis of Mutant Escherichia coli ? Clamps Provides Insight Into the Role of Clamp in umuDC-Mediated Cold Sensitivity  

PubMed Central

The E. coli umuDC gene products participate in two temporally distinct roles: UmuD2C acts in a DNA damage checkpoint control, while UmuD'2C, also known as DNA polymerase V (Pol V), catalyzes replication past DNA lesions via a process termed translesion DNA synthesis. These different roles of the umuDC gene products are managed in part by the dnaN-encoded ? sliding clamp protein. Co-overexpression of the ? clamp and Pol V severely blocked E. coli growth at 30°C. We previously used a genetic assay that was independent of the ability of ? clamp to support E. coli viability to isolate 8 mutant clamp proteins (?Q61K, ?S107L, ?D150N, ?G157S, ?V170M, ?E202K, ?M204K and ?P363S) that failed to block growth at 30°C when co-overexpressed with Pol V. It was unknown whether these mutant clamps were capable of supporting E. coli viability and normal umuDC functions in vivo. The goals of this study were to answer these questions. To this end, we developed a novel dnaN plasmid shuffle assay. Using this assay, ?D150N and ?P363S were unable to support E. coli viability. The remaining 6 mutant clamps, each of which supported viability, were indistinguishable from ?+ with respect to umuDC functions in vivo. In light of these findings, we analyzed phenotypes of strains overexpressing either ? clamp or Pol V alone. The strain overexpressing ?+, but not those expressing mutant ? clamps, displayed slowed growth irrespective of the incubation temperature. Moreover, growth of the Pol V-expressing strain was modestly slowed at 30°, but not 42°C. Taken together, these results suggest the mutant clamps were identified due to their inability to slow growth rather than an inability to interact with Pol V. They further suggest that cold sensitivity is due, at least in part, to the combination of their individual effects on growth at 30°C.

Babu, Vignesh M. P.; Sutton, Mark D.

2014-01-01

273

Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials  

NASA Astrophysics Data System (ADS)

A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill's 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill's 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger's effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multi-stage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.

Taherizadeh, Aboozar; Green, Daniel E.; Yoon, Jeong W.

2013-12-01

274

Computer modelling of age hardening for cast aluminium alloys  

NASA Astrophysics Data System (ADS)

Age hardening, or precipitation hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age hardening models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution hardening and precipitation hardening.

Wu, Linda; Ferguson, W. George

2009-08-01

275

Reduction of work hardening rate in low-carbon steels  

NASA Astrophysics Data System (ADS)

Low carbon grades of steel rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subject to ductility failures during production due to excessively high work hardening rates during wire drawing. The high work hardening rates are attributed to the presence of residuals, free nitrogen, or combinations thereof. This research concludes that the most cost-effective way to reduce the work hardening rate during wire drawing is to combine boron with nitrogen to form boron nitride, and thus reducing its work hardening contribution. The results of this study also conclude the following: (1) Boron/Nitrogen ratio is the more significant factor than rod tensile strength, which affects work hardening rate. Higher ratio is better in the 0.79 to 1.19 range. (2) Maintaining this narrow B/N range requires precise process control. (3) Process conditions such as dissolved oxygen (<25 ppm), carbon (?0.05%) and ladle refining temperature (<2930°F) are necessary for optimizing boron recovery. (4) An average of 89% boron recovery is obtained with the above controlled process conditions. (5) Use of Boron has no adverse effects on the several metallurgical properties tested except with minor difficulty with scale for descaling. North Star Steel Texas (North Star) benefited from this research by being able to provide a competitive edge in both quality and cost of its low carbon boron grades thus making North Star a preferred supplier of wire rod for these products.

Yalamanchili, Bhaskar Rao

276

Hardening treatment of machine parts with CO2 power lasers  

NASA Astrophysics Data System (ADS)

Two technological laser facilities were built at the All-Union Scientific Research Institute of Electrothermal Equipment for hardening machine parts using 1.2 and 2.5 kW CO2 lasers. Both lasers are continuous wave devices with self sustained gas discharge between flat anode and tubular cathode. Each facility includes a Fabry-Perot resonator, a beam transporting and focusing mechanism, a laser power measuring instrument with a movable beam chopping mirror, and a helium/neon simulating laser with two mirrors for precision alignment of parts. These facilities are intended not only for hardening, but also for annealing, plating, and alloying. Under consideration is also use for welding and cutting. Materials hardenable with these facilities range from perlite iron to chromium steels. Experimentally hardened parts include tool bits, gear teeth, zinc extrusion plungers, bearing races, king pins, bolts, and even diesel cylinders. Hardening is done to ensure high wear resistance of the materials and long service life for the part.

Borodachev, A. S.; Gutman, M. B.; Kuznetsov, G. A.; Medvedovskaya, L. A.; Rubin, G. K.

1986-01-01

277

Solute hardening and softening effects in B2 nickel aluminides  

SciTech Connect

The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.

Pike, L.M.; Liu, C.T.; Anderson, I.M. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering

1998-11-01

278

Physiological mechanisms of frost tolerance: Possible role of protein in plant adaptation to cold  

Microsoft Academic Search

Studies performed on winter rape plants(Brassica nnpus var.oleifera, cv. ‘Gór-cza?ski’) revealed that cold treatment affected the cell membranes and led to the temporary increase in electrolytic\\u000a leakage from a tissue. This was followed by the marked decrease of the electrolytic leakage in the course of hardening. Changes\\u000a in membrane properties were accompanied by the promotion of soluble protein accumulation. Inhibition

Alina Kacperska-Palacz; Ewa Dlugokecka; Jolanta Breitenwald; Barbara Wci?li?ska

1977-01-01

279

Proteolysis of Xenopus laevis egg envelope ZPA triggers envelope hardening.  

PubMed

The egg envelope of most animal eggs is modified following fertilization, resulting in the prevention of polyspermy and hardening of the egg envelope. In frogs and mammals a prominent feature of envelope modification is N-terminal proteolysis of the envelope glycoprotein ZPA. We have purified the ZPA protease from Xenopus laevis eggs and characterized it as a zinc metalloprotease. Proteolysis of isolated egg envelopes by the isolated protease resulted in envelope hardening. The N-terminal peptide fragment of ZPA remained disulfide bond linked to the ZPA glycoprotein moiety following proteolysis. We propose a mechanism for egg envelope hardening involving ZPA proteolysis by an egg metalloprotease as a triggering event followed by induction of global conformational changes in egg envelope glycoproteins. PMID:15474476

Lindsay, Leann L; Hedrick, Jerry L

2004-11-12

280

Effect of cold compression on precipitation and conductivity of an Al-Li-Cu alloy.  

PubMed

Transmission electron microscopy has been used to investigate the effect of increasing the degree of deformation applied by cold compression on the ageing kinetics and electrical conductivity response of an Al-Li-Cu alloy containing Mg and Ag. When cold compressed greater than 3%, the increased dislocation density accelerates the widespread precipitation of the T(1) phase resulting in an enhanced age hardening response. The lengthening rate of T(1) precipitates is also reduced in this cold compressed condition owing to the reduced local solute supersaturation, a result of the widespread precipitation of T(1) plates. Cold compression by less than 3% does not increase the age hardening response, and the precipitation of GP zones/theta'' appears to be suppressed. Precipitation of the T(1) phase is also not significantly enhanced compared with that of the more than 3% cold compressed conditions. The anomalous decrease in electrical conductivity is associated with the nucleation and growth of the T(1) phase. Strain fields around T(1) precipitates combined with the increased volume fraction of T(1) are thought to be the cause of the anomalous conductivity behaviour. PMID:19094036

Khan, A K; Robinson, J S

2008-12-01

281

Surviving the Cold  

MedlinePLUS Videos and Cool Tools

... HealthDay January 31, 2014 Related MedlinePlus Pages Frostbite Hypothermia Winter Weather Emergencies Transcript Millions of Americans are ... dangerous cold-related complications such as frostbite or hypothermia. Luckily, protection can be found in just a ...

282

Cold Weather Aerostat Study.  

National Technical Information Service (NTIS)

Aerostats are being considered for application in cold weather regions. A review of aerostat flight experience to date was made to determine the limitations of the current technology. Areas for improvements and modifications to extend the aerostat system ...

R. L. Ashford

1982-01-01

283

Cold hardiness in molluscs  

NASA Astrophysics Data System (ADS)

Molluscs inhabit all types of environments: seawater, intertidal zone, freshwater and land, and of course may have to deal with subzero temperatures. Ectotherm animals survive cold conditions by avoiding it by extensive supercooling (freezing avoidant species) or by bearing the freezing of their extracellular body fluids (freezing tolerant species). Although some studies on cold hardiness are available for intertidal molluscs, they are scarce for freshwater and terrestrial ones. Molluscs often exhibit intermediary levels of cold hardiness, with a moderate or low ability to supercool and a limited survival to the freezing of their tissues. Several factors could be involved: their dependence on water, their ability to enter dormancy, the probability of inoculative freezing in their environment, etc. Size is an important parameter in the development of cold hardiness abilities: it influences supercooling ability in land snails, which are rather freezing avoidant and survival to ice formation in intertidal organisms, which generally tolerate freezing.

Ansart, Armelle; Vernon, Philippe

2003-05-01

284

Aerostat Cold Weather Study.  

National Technical Information Service (NTIS)

The arctic environment and its potential impact on Aerostat design and operations are discussed. Predictive meteorological resources available are summarized. Results of previous Aerostat operations in cold climates are reviewed and potential solutions di...

D. L. Kane

1989-01-01

285

Vitamin C and colds  

MedlinePLUS

Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev . 2007 Jul 18;(3):CD000980. Kilgore D. Common respiratory diseases. Prim ...

286

Cold and Cough Medicines  

MedlinePLUS

... or cough symptoms? Besides drinking plenty of fluids and getting plenty of rest, you may want to take medicines. There are lots of different cold and cough medicines, and they do different things. Nasal ...

287

Impact of laser beam profiles in transformation hardening processing  

NASA Astrophysics Data System (ADS)

The performance of a high power laser in material processing is strongly dependent on the laser beam intensity distribution. In particular, the uniformity of the beam intensity during laser transformation hardening is a critical factor in the success of the process. The results of tests on a new class of beam-integrating infrared optics used in the transformation hardening process are presented here. These complex, multi-faceted lenses have been manufactured, assembled in laser processing systems, and tested in optical experiments that correlate laser beam characteristics, integrator performance, and successful process completion.

Ferravante, Lidia; Mor, Giovanni P.; Serri, Laura; Foote, Frank B.

1993-04-01

288

Diffusive Origin of the Cosmic-Ray Spectral Hardening  

NASA Astrophysics Data System (ADS)

Recent data from ATIC, CREAM and PAMELA revealed that the energy spectra of cosmic ray (CR) nuclei above 100 GeV/nucleon experience a remarkable hardening with increasing energy. This effect cannot be recovered by the conventional descriptions of CR acceleration and diffusive propagation processes. Using analytical calculations, I show that the hardening effect can be consequence of a spatial change of the CR diffusion properties in different regions of the Galaxy. I discuss the implications of this scenario for the main CR observables and its connections with the open issues of the CR physics.

Tomassetti, Nicola

2013-02-01

289

Method and apparatus for welding precipitation hardenable materials  

DOEpatents

A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.

Murray, Jr., Holt (Hopewell, NJ); Harris, Ian D. (Dublin, OH); Ratka, John O. (Cleveland Heights, OH); Spiegelberg, William D. (Parma, OH)

1994-01-01

290

Quantification of overaging hardening kinetics of aluminum alloys  

Microsoft Academic Search

The overaging hardening kinetics in several aluminum alloys has been quantified, based on a relation between hardness and\\u000a time for precipitation-hardened alloys. The relation takes into account precipitate coarsening and Orowan bowing mechanisms.\\u000a Hardness-time curves from literature data for Al-2.5Cu-1.5Mg-(Si,Ag) (wt pct) alloys at 200 C and for an Al-1.23Mg-1.64Cu-6.15Zn\\u000a (wt pct) alloy at 120 C are analysed, which are

W. Sha; A. E. Long

2004-01-01

291

Method and apparatus for welding precipitation hardenable materials  

DOEpatents

A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.

Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.

1994-06-28

292

Measurement and analysis of plane-strain work hardening  

Microsoft Academic Search

A new technique for measurement of plane-strain work hardening has been developed which uses tensile loading and computer\\u000a analysis for interpretation, and which eliminates the experimental uncertainties of large strain gradients, friction, and\\u000a out-of-plane bending inherent in the usual plane-strain deformation modes. Plane-strain and tensile work-hardening curves\\u000a have been measured for 2036-T4 aluminum alloy using several types of sheet specimens.

R. H. Wagoner

1980-01-01

293

Electrically induced temperature difference and deformation in hardened cement pastes  

SciTech Connect

Electromechanical effect of hardened cement paste beam is investigated in this paper. When an external electrical current is applied to the electrodes attached to opposite surfaces of a cement beam, it is found that temperature on the positive electrode is always higher than that on the negative electrode. The sign of electrically induced temperature difference is determined by the direction of applied electrical current. Electrically induced temperature difference makes the beam bend towards the surface with a higher temperature. Both electrically induced temperature difference and electroosmosis lead to electromechanical effect of hardened cement paste. Finally, electromechanical effect becomes more obvious by adding NaCl to cement paste.

Sun Mingqing [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)]. E-mail: sunmingqing@yahoo.com; Wang Xiaoying [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Zhao Kairui [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Li Zhuoqiu [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)

2006-12-15

294

Non-conventional laser surface hardening for axisymmetric components  

NASA Astrophysics Data System (ADS)

A new process, based on ring spot geometry, is presented for laser surface hardening of large cylindrical com-ponents. The proposed technique leads to a very hard, deep and uniform treated area along the entire work piece surface without introducing a tempered zone, making the process very attractive compared to conventional induction hardening that exhibits both low energy efficiency and poor flexibility. A complete physical model is presented for the process, together with a study of the influence of process parameters on the final outcome. The results of an extensive validation campaign, carried out following the AISI1040 standard, are also reported.

Liverani, Erica; Battiato, Nadine; Ascari, Alessandro; Fortunato, Alessandro

2014-02-01

295

Impact of Scaled Technology on Radiation Testing and Hardening  

NASA Technical Reports Server (NTRS)

This presentation gives a brief overview of some of the radiation challenges facing emerging scaled digital technologies with implications on using consumer grade electronics and next generation hardening schemes. Commercial semiconductor manufacturers are recognizing some of these issues as issues for terrestrial performance. Looking at means of dealing with soft errors. The thinned oxide has indicated improved TID tolerance of commercial products hardened by "serendipity" which does not guarantee hardness or say if the trend will continue. This presentation also focuses one reliability implications of thinned oxides.

LaBel, Kenneth A.; Cohn, Lewis M.

2005-01-01

296

STUDIES ON THE COMMON COLD  

PubMed Central

1. Studies of the cultivation of the virus of common cold in tissue medium, and the capacity of the culture virus to induce infection in human volunteers are reported. 2. Detailed descriptions are given of the methods employed to isolate the virus, preserve and cultivate it, and to test its activity in human volunteers. 3. The virus of common cold can easily be isolated from properly selected patients and cultivated in tissue medium. 4. When kept in the original nasopharyngeal washings, the virus will survive at ice box temperature under anaerobic conditions for at least 13 days. 5. If the nasopharyngeal washings are frozen and dried in vacuo, the virus retains its activity for at least 4 months. 6. The virus of common cold has been proven to multiply in medium containing chick embryo tissue. Such cultures retain their capacity to produce typical infections in human beings for many transfers involving a period of several months. Attempts to cultivate the virus have been successful in seven out of eight instances. 7. Prolonged cultivation of the virus in tissue medium eventually leads to a loss of activity. 8. Strains of virus under cultivation maintain their potency best when transfers are made at 2 and 3 day intervals. 9. After removal from the incubator a culture of virus rapidly becomes inactive whether it be kept under seal in the ice box or frozen and dried in vacuo. 10. The destructive action of the medium can be prevented if the culture is mixed with gum acacia before freezing and drying in vacuo.

Dochez, A. R.; Mills, K. C.; Kneeland, Yale

1936-01-01

297

Cyanobacteria in Cold Ecosystems  

Microsoft Academic Search

Perennially cold environments in which temperatures remain below 5°C are common throughout the biosphere (Margesin and Häggblom\\u000a 2007). In these habitats, the persistent cold temperatures are often accompanied by freeze—thaw cycles, extreme fluctuations\\u000a in irradiance (including ultraviolet radiation), and large variations in nutrient supply and salinity. As a result of these\\u000a constraints, polar and alpine environments contain a reduced biodiversity,

Frédéric Zakhia; Anne-Dorothee Jungblut; Arnaud Taton; Warwick F. Vincent; Annick Wilmotte

298

Preparation of in situ hardening composite microcarriers: Calcium phosphate cement combined with alginate for bone regeneration  

PubMed Central

Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution?=?0.8–1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement–alginate microcarriers under moist conditions due to the conversion of the ?-tricalcium phosphate phase in the calcium phosphate cement into a carbonate–hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement–alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone.

Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C

2014-01-01

299

Study on the hardened case discrepancy between the beginning and the end of laser scanning in laser transformation hardening  

NASA Astrophysics Data System (ADS)

In laser transformation hardening (LTH), it is a common phenomenon that the discrepancy of hardening effects occurs between the beginning and the end of laser scanning for those parts which have boundaries along the scanning direction, when the laser processing parameters, laser power and scanning velocity, are kept unchanged. The case depth at the end of scanning path is larger than that at the beginning. And sometime the local surface on the end may be melted. The discrepancy, which results in non-uniform hardening effect, will make the process quality bad. This paper study on the discrepancy and the effects of laser power and scanning velocity, then presents the effective method to control the discrepancy and to improve the laser process.

Wu, Gang; Song, Guangming

2005-01-01

300

Isocurvature cold dark matter fluctuations  

NASA Technical Reports Server (NTRS)

According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

Efstathiou, G.; Bond, J. R.

1986-01-01

301

Processing, Microstructures and Properties of a Dual Phase Precipitation-Hardening PM Stainless Steel  

NASA Astrophysics Data System (ADS)

To improve the mechanical properties of PM stainless steels in comparison with their wrought counterparts, a PM stainless steel alloy was developed which combines a dual-phase microstructure with precipitation-hardening. The use of a mixed microstructure of martensite and ferrite results in an alloy with a combination of the optimum properties of each phase, namely strength and ductility. The use of precipitation hardening via the addition of copper results in additional strength and hardness. A range of compositions was studied in combination with various sintering conditions to determine the optimal thermal processing to achieve the desired microstructure. The microstructure could be varied from predominately ferrite to one containing a high percentage of martensite by additions of copper and a variation of the sintering temperature before rapid cooling. Mechanical properties (transverse rupture strength (TRS), yield strength, tensile strength, ductility and impact toughness) were measured as a function of the v/o ferrite in the microstructure. A dual phase alloy with the optimal combination of properties served as the base for introducing precipitation hardening. Copper was added to the base alloy at various levels and its effect on the microstructure and mechanical properties was quantified. Processing at various sintering temperatures led to a range of microstructures; dilatometry was used utilized to monitor and understand the transformations and the formation of the two phases. The aging process was studied as a function of temperature and time by measuring TRS, yield strength, tensile strength, ductility, impact toughness and apparent hardness. It was determined that optimum aging was achieved at 538°C for 1h. Aging at slightly lower temperatures led to the formation of carbides, which contributed to reduced hardness and tensile strength. As expected, at the peak aging temperature, an increase in yield strength and ultimate tensile strength as well as apparent hardness was found. Aging also lead to an unexpected and concurrent increase in ductility and impact toughness. The alloys also showed an increase in strain hardening on aging. The increase in ductility varied with the v/o martensite in the microstructure and was shown to occur after short time intervals at the optimum aging temperature. Compressive strength measurements revealed that the increase in ductility was due to the relaxation of residuals stresses that occur when the high temperature austenite transforms to martensite in the dual phase microstructure. The specific volume of martensite is much larger than that of austenite so that when the transformation takes place, a compressive stress is induced in the ferrite. In the sintered state, the residual stress leads to a higher work hardening rate in tension. When the alloy is aged, the work hardening rate is reduced and the ductility is increased compared with the sintered state, even though aging increases the strength and apparent hardness.

Schade, Christopher

302

Teaching in a Cold Environment.  

ERIC Educational Resources Information Center

Designed to help teachers deal with students in a cold environment, this article explains cold physiology and fundamental laws of heat; describes 14 common cold injuries and their current treatment; and lists a number of useful teaching techniques for cold environments. (SB)

Ewert, Alan

1979-01-01

303

Contribuicao ao estudo de recuperacao e recristalizacao do zircaloy-4 laminado a frio. (Contribution to study on recovery and recrystallization of cold rolling zircaloy-4).  

National Technical Information Service (NTIS)

Recovery and recrystallization of work-hardened (40-60% - Cold rolling) Zircaloy-4 were studied between 200 and 600(sup 0) C with times varying from 15 to 240 minutes, from electrical resistance and hardness measurements. Activation energy calculation for...

A. I. C. Persiano

1977-01-01

304

Laser surface hardening of gray cast iron used for piston ring  

Microsoft Academic Search

The process parameters for laser surface-hardening has been experimentally established for improving the wear life of piston\\u000a rings used for marine diesel engines by the formation of a proper hardened layer on it. The parameters of interest were the\\u000a laser power and travel speed. Various hardened layers of gray cast iron were analyzed with respect to microstructure, hardness\\u000a value, hardening

Jong-Hyun Hwang; Dae-Young Kim; Joong-Geun Youn; Yun-Sig Lee

2002-01-01

305

Thermal analysis of the laser surface transformation hardening process  

Microsoft Academic Search

An analytical solution for the temperature rise distribution in laser surface transformation hardening of a steel workpiece of finite width is developed based on Jaeger's classical moving heat source method [Proc. Roy. Soc. NSW 76 (1942) 203] and Carlsaw and Jaeger [Conduction of heat in solids, Oxford University Press, Oxford, UK, 1959] to predict the optimal operational parameters. The laser

R. Komanduri; Z. B. Hou

2001-01-01

306

Classification of microstructural changes in laser hardened steel surfaces  

Microsoft Academic Search

Three different steels with C contents of ?0.2 wt.% and different contents of chromium, molybdenum and vanadium were similarly laser hardened after different preceding heat treatments. The laser-affected zones beneath the surface were characterised by microhardness, dislocation density, carbide type, size and distribution as well as grain size of the austenite. By a systematic study of the changes in microstructure

K. Obergfell; V. Schulze; O. Vöhringer

2003-01-01

307

Modelling of temperature evolution on metals during laser hardening process  

Microsoft Academic Search

To achieve a precise and controlled laser process, an exhaustive analysis of the thermal behaviour of the material is necessary. In the present paper, a numerical simulation of the laser hardening process has been developed using both analytical solutions and the finite element code ANSYS™ to solve the heat transfer equation inside the treated material. The knowledge of the thermal

A. Yánez; J. C. Álvarez; A. J. López; G. Nicolás; J. A. Pérez; A. Ramil; E. Saavedra

2002-01-01

308

Machinability of hardened steel using alumina based ceramic cutting tools  

Microsoft Academic Search

Alumina based ceramic cutting tool is an attractive alternative for carbide tools in the machining of steel in its hardened condition. These ceramic cutting tools can machine with high cutting speed and produce good surface finish. The wear mechanism of these ceramic cutting tools should be properly understood for greater utilization. Two types of ceramic cutting tools namely Ti[C,N] mixed

A Senthil Kumar; A Raja Durai; T Sornakumar

2003-01-01

309

Laser Transformation Hardening of Precision V-Slide Way.  

National Technical Information Service (NTIS)

The paper presents the results of the study of the application of laser transformation hardening (LTH) on the precision slide ways and some specimens of 20, 45, GCr15, 18Cr2Ni4WA or other steels by 1KW transverse CO2 laser. It is concluded that (1) the LT...

G. Zhang Q. Yang Y. Wu

1986-01-01

310

RTM of Italy applies power lasers to welding, hardening  

Microsoft Academic Search

The Institute for Mechanical Technology Research and Automation (RTM) has five power lasers, including one with a 15-kW output all lasers are used for process development like, sheet metal welding and spot hardening feasibility tests of mechanical part machining and surface treatment are described.

A. Larane

1985-01-01

311

BUSFET - A Novel Radiation-Hardened SOI Transistor  

SciTech Connect

A partially-depleted SOI transistor structure has been designed that does not require the use of specially-processed hardened buried oxides for total-dose hardness and maintains the intrinsic SEU and dose rate hardness advantages of SOI technology.

Dodd, P.E.; Draper, B.L.; Schwank, J.R.; Shaneyfelt, M.R.

1999-02-04

312

Laser surface hardening of AISI H13 tool steel  

Microsoft Academic Search

An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating source. The hardness of laser melted zone was investigated. In order to identify the effect of heat input on the laser melting zone, scanning conditions

Jae-Ho LEE; Jeong-Hwan JANG; Byeong-Don JOO; Young-Myung SON; Young-Hoon MOON

2009-01-01

313

Analysis of the Work-Hardening Process in Spheroidized Steels.  

National Technical Information Service (NTIS)

An elementary model for the work-hardening process in duplex-structures steels (ferrite - spheroidite) is proposed and tested on low, medium and high carbon content, which seems to give good results concerning the influence of the volume fraction and part...

J. L. Pacheco

1981-01-01

314

Hardening digital systems with distributed functionality: robust networks  

NASA Astrophysics Data System (ADS)

Collaborative hardening and hardware redundancy are nowadays the most interesting solutions in terms of fault tolerance achieved and low extra cost imposed to the project budget. Thanks to the powerful and cheap digital devices that are available in the market, extra processing capabilities can be used for redundant tasks, not only in early data processing (sensed data) but also in routing and interfacing1

Vaskova, Anna; Portela-Garcia, Marta; Garcia-Valderas, Mario; López-Ongil, Celia; Portilla, Jorge; Valverde, Juan; de la Torre, Eduardo; Riesgo, Teresa

2013-05-01

315

Bake hardening of nanograin AA7075 aluminum alloy  

Microsoft Academic Search

In the present work, the bake hardening of nanostructured AA7075 aluminum alloy was compared with that of its coarse-grain counterpart. Surface severe plastic deformation (SSPD) was used to produce nanograin layers on both surfaces of workpieces. The nanostructured layers were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The thickness of nanostructured layer, having the grains

Kamran Dehghani

316

THE PHYSICAL METALLURGY OF PRECIPITATION-HARDENABLE STAINLESS STEELS  

Microsoft Academic Search

The present knowledge on the physical metallurgy of precipitation-; hardenable stainless steels is presented. The alloys discussed include the ; martensitic types (Stainless W and 17-4 PH), the semiaustenitic types (177 PH, PH ; 15-7 Mo, AM 350, and AM 355), and the austenitic types (A-286 and HNM). The ; areas of metallurgy common to most or all of these

D. C. Ludwigson; A. M. Hall

1959-01-01

317

Surface hardening of ductile cast iron using stainless steel  

Microsoft Academic Search

A surface hardening technique for improving the wear resistance of ductile cast iron (DI) is proposed by fabricating molten DI with stainless steel. The essential idea is concerned with using the chromium source in stainless steel and the carbon source in DI to form chromium carbides. It was demonstrated that the surface of the fabricated DI consisted of firstly a

Ma Qian; Shoji Harada; Yoshihito Kuroshima; Hideaki Nagayoshi

1996-01-01

318

Hot Machining of Hardened Steels with Coated Carbide Inserts  

Microsoft Academic Search

Problem statement: The benefits of easier manufacture of hardened ste el components can be substantial in terms of reduced machining costs and lead times compared to the traditional route involving machining of the annealed state followed by heat treatment, grinding\\/EDM and manual finishing. But machinability of hard material throu gh conventional machining is hindered due to excessive wear of the

M. A. Lajis; A. K. M. N. Amin; A. N. M. Karim; H. C. D. M. Radzi; T. L. Ginta

2009-01-01

319

Ferritic, martensitic, and precipitation hardening stainless steel laser weldings  

Microsoft Academic Search

Even if many steels and alloys have been welded on the last years, nowadays there are some other stainless steel alloys that need a further comprehension when they have to be welded. Typically these alloys are martensitic and precipitation hardening ones that still present some problems to be weld, i.e. hot cracks, fragile beads, an excessive grain size and other

Giuseppe Daurelio; Antonio D. Ludovico; Christos N. Panagopoulos; Corrado Tundo

1998-01-01

320

Radiation Hardening in Magnox Pressure-Vessel Steels  

Microsoft Academic Search

The ferritic steels used for reactor pressure vessels undergo a marked transition from ductile to brittle fracture behaviour over a relatively narrow temperature range. For most unirradiated mild steels the ductile to brittle transition temperature (d.b.t.t.) is between -50 degrees and 20 degrees C. The process of irradiation hardening, through the formation of clusters of intersitial or vacancy defects, increases

S. B. Fisher; J. E. Harbottle; N. Aldridge

1985-01-01

321

PRECIPITATION-HARDENING STAINLESS STEELS IN WATER-COOLED REACTORS  

Microsoft Academic Search

A study is made of the stress corrosion susceptibiity of unirradiated ; precipitation-hardening stainless steels. This study is made because of the ; failures encouatered with these materials in the Dresden and Vallecltos boiling ; water reactors. Service experience, static steam autoclave tests, and dynamic ; water and steam corrosion loop tests have demonstrated that 17-4 PH in the high-;

M. C. Rowland; W. R. Sr. Smith

1962-01-01

322

Microstructure of precipitation hardened cobalt rare earth permanent magnets  

Microsoft Academic Search

A transmission electron microscope study of several precipitation hardened cobalt rare earth magnets has been undertaken. The magnets were in peak aged condition and varied in the chemical composition. The studies reveal a fine cellular microstructure. The shape and size of cells depend on the heat treatment and alloying elements. The cell interiors consist of at least two plate-shaped 17:2

J. Fidler; P. Skalicky

1982-01-01

323

Strain hardening of polymer glasses: Entanglements, energetics, and plasticity  

Microsoft Academic Search

Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend

Robert S. Hoy; Mark O. Robbins

2008-01-01

324

Modelling of work hardening and stress saturation in FCC metals  

Microsoft Academic Search

A work hardening theory has been developed based on a microstructural concept comprising three elements; the cell\\/subgrain size, ?, the dislocation density inside the cells, ?i, and the cell boundary dislocation density or the sub boundary misorientation, ?b or ?. The theory is based on a statistical approach to the storage of dislocations. This approach predicts that the slip length,

Erik Nes

1997-01-01

325

49. INTERIOR VIEW OF HARDENER AREA SHOWING GAUGE THAT MEASURES ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

49. INTERIOR VIEW OF HARDENER AREA SHOWING GAUGE THAT MEASURES HARDNESS, THE NAIL MUST BREAK IN THE CENTER RANGE OF THE CURVED BAR TO HAVE THE CORRECT HARDNESS (THE NAIL WILL BREAK TOO EASILY IF TOO HARD AND WILL BEND TOO MUCH IF TOO SOFT) - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

326

UVA rush hardening for the treatment of solar urticaria  

Microsoft Academic Search

Induction of tolerance by subsequent UV exposures is the most effective therapy for solar urticaria; however, it is time-consuming and takes a long time until protection is achieved. Three patients with solar urticaria were exposed to multiple UVA irradiations at 1-hour intervals per day. With this rush hardening regimen, protection was achieved within 3 days.

Stefan Beissert; Hartmut Ständer; Thomas Schwarz

2000-01-01

327

UVA rush hardening for the treatment of solar urticaria.  

PubMed

Induction of tolerance by subsequent UV exposures is the most effective therapy for solar urticaria; however, it is time-consuming and takes a long time until protection is achieved. Three patients with solar urticaria were exposed to multiple UVA irradiations at 1-hour intervals per day. With this rush hardening regimen, protection was achieved within 3 days. PMID:10827409

Beissert, S; Ständer, H; Schwarz, T

2000-06-01

328

Shape deformation of a piston ring groove by laser surface hardening  

Microsoft Academic Search

With laser beam heating it is possible to obtain a precisely controlled hardening area, in which the process parameters and material properties are important for the hardened area and deformed surface shape. In this study, the transient heat flow, thermal stress and deformed shape during laser surface hardening of the piston ring groove of a ship's engine were analysed by

K.-K. Yoon; W.-B. Kim; S.-J. Na

1996-01-01

329

Influence of cyclic temperature changes on the microstructure of AISI 4140 after laser surface hardening  

Microsoft Academic Search

In recent years laser surface hardening using pulsed laser sources has become an increasingly established technology in engineering industry and has opened up wider possibilities for the application of selective surface hardening. However, the choice of the process parameters is generally based on experience rather than on their empirical influence on the resulting microstructure, and for hardening processes with cyclic

T. Miokovi?; V. Schulze; O. Vöhringer; D. Löhe

2007-01-01

330

Strain hardening behavior of nanostructured dual-phase steel processed by severe plastic deformation  

Microsoft Academic Search

The strain hardening behavior of nanostructured dual-phase steel fabricated by equal channel angular pressing together with subsequent intercritical annealing treatment was investigated. In contrast to conventional nanostructured steels that have negligible strain hardening capability in tension, the nanostructured dual-phase steel exhibited excellent strain hardenability due to the nanoscale grains of each constituent phase and their uniform distribution of them as

Young Gun Ko; Chul Won Lee; Seung Namgung; Dong Hyuk Shin

2010-01-01

331

Development and performance evaluation of a producer gas based system for hardening of steels  

Microsoft Academic Search

A producer gas (PG) based system for steel hardening, had been developed by the Institute. This developed PG based system consists of a batch type updraft gasifier, an air swirling type PG burner and a hardening furnace. In this developmental work, a local industry engaged in steel hardening was involved. At present, the industry is using a traditional coal based

P. V. Ramana; R. N. Singh; K. N. Patil

2005-01-01

332

Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring  

NASA Astrophysics Data System (ADS)

Thermal diffusivity and conductivity of dental cements have been studied using open photoacoustic cell (OPC). The samples consisted of fast hardening cement named CER, developed to be a root-end filling material. Thermal characterization was performed in samples with different gel/powder ratio and particle sizes and the results were compared to the ones from commercial cements. Complementary measurements of specific heat and mass density were also performed. The results showed that the thermal diffusivity of CER tends to increase smoothly with gel volume and rapidly against particle size. This behavior was linked to the pores size and their distribution in the samples. The OPC method was shown to be a valuable way in deriving thermal properties of porous material.

Astrath, F. B. G.; Astrath, N. G. C.; Baesso, M. L.; Bento, A. C.; Moraes, J. C. S.; Santos, A. D.

2012-01-01

333

Nanoscale characterization of the biomechanical hardening of bovine zona pellucida.  

PubMed

The zona pellucida (ZP) is an extracellular membrane surrounding mammalian oocytes. The so-called zona hardening plays a key role in fertilization process, as it blocks polyspermy, which may also be caused by an increase in the mechanical stiffness of the ZP membrane. However, structural reorganization mechanisms leading to ZP's biomechanical hardening are not fully understood yet. Furthermore, a correct estimate of the elastic properties of the ZP is still lacking. Therefore, the aim of the present study was to investigate the biomechanical behaviour of ZP membranes extracted from mature and fertilized bovine oocytes to better understand the mechanisms involved in the structural reorganization of the ZP that may lead to the biomechanical hardening of the ZP. For that purpose, a hybrid procedure is developed by combining atomic force microscopy nanoindentation measurements, nonlinear finite element analysis and nonlinear optimization. The proposed approach allows us to determine the biomechanical properties of the ZP more realistically than the classical analysis based on Hertz's contact theory, as it accounts for the nonlinearity of finite indentation process, hyperelastic behaviour and material heterogeneity. Experimental results show the presence of significant biomechanical hardening induced by the fertilization process. By comparing various hyperelastic constitutive models, it is found that the Arruda-Boyce eight-chain model best describes the biomechanical response of the ZP. Fertilization leads to an increase in the degree of heterogeneity of membrane elastic properties. The Young modulus changes sharply within a superficial layer whose thickness is related to the characteristic distance between cross-links in the ZP filamentous network. These findings support the hypothesis that biomechanical hardening of bovine ZP is caused by an increase in the number of inter-filaments cross-links whose density should be higher in the ZP inner side. PMID:22675161

Boccaccio, Antonio; Frassanito, Maria Cristina; Lamberti, Luciano; Brunelli, Roberto; Maulucci, Giuseppe; Monaci, Maurizio; Papi, Massimiliano; Pappalettere, Carmine; Parasassi, Tiziana; Sylla, Lakamy; Ursini, Fulvio; De Spirito, Marco

2012-11-01

334

Nanoscale characterization of the biomechanical hardening of bovine zona pellucida  

PubMed Central

The zona pellucida (ZP) is an extracellular membrane surrounding mammalian oocytes. The so-called zona hardening plays a key role in fertilization process, as it blocks polyspermy, which may also be caused by an increase in the mechanical stiffness of the ZP membrane. However, structural reorganization mechanisms leading to ZP's biomechanical hardening are not fully understood yet. Furthermore, a correct estimate of the elastic properties of the ZP is still lacking. Therefore, the aim of the present study was to investigate the biomechanical behaviour of ZP membranes extracted from mature and fertilized bovine oocytes to better understand the mechanisms involved in the structural reorganization of the ZP that may lead to the biomechanical hardening of the ZP. For that purpose, a hybrid procedure is developed by combining atomic force microscopy nanoindentation measurements, nonlinear finite element analysis and nonlinear optimization. The proposed approach allows us to determine the biomechanical properties of the ZP more realistically than the classical analysis based on Hertz's contact theory, as it accounts for the nonlinearity of finite indentation process, hyperelastic behaviour and material heterogeneity. Experimental results show the presence of significant biomechanical hardening induced by the fertilization process. By comparing various hyperelastic constitutive models, it is found that the Arruda–Boyce eight-chain model best describes the biomechanical response of the ZP. Fertilization leads to an increase in the degree of heterogeneity of membrane elastic properties. The Young modulus changes sharply within a superficial layer whose thickness is related to the characteristic distance between cross-links in the ZP filamentous network. These findings support the hypothesis that biomechanical hardening of bovine ZP is caused by an increase in the number of inter-filaments cross-links whose density should be higher in the ZP inner side.

Boccaccio, Antonio; Frassanito, Maria Cristina; Lamberti, Luciano; Brunelli, Roberto; Maulucci, Giuseppe; Monaci, Maurizio; Papi, Massimiliano; Pappalettere, Carmine; Parasassi, Tiziana; Sylla, Lakamy; Ursini, Fulvio; De Spirito, Marco

2012-01-01

335

How cold pool triggers deep convection?  

NASA Astrophysics Data System (ADS)

The cold pool in the boundary layer is often considered a major triggering mechanism of convection. Here, presented are basic theoretical considerations on this issue. Observations suggest that cold pool-generated convective cells is available for shallow maritime convection (Warner et al. 1979; Zuidema et al. 2012), maritime deep convection (Barnes and Garstang 1982; Addis et al. 1984; Young et al. 1995) and continental deep convection (e.g., Lima and Wilson 2008; Flamant 2009; Lothon et al. 2011; Dione et al. 2013). Moreover, numerical studies appear to suggest that cold pools promote the organization of clouds into larger structures and thereby aid the transition from shallow to deep convection (Khairoutdinov and Randall 2006, Boing et al. 2012, Schlemmer and Hohenegger, 2014). Even a cold--pool parameterization coupled with convection is already proposed (Grandpeix and Lafore 2010: but see also Yano 2012). However, the suggested link between the cold pool and deep convection so far is phenomenological at the best. A specific process that the cold pool leads to a trigger of deep convection must still to be pinned down. Naively, one may imagine that a cold pool lifts up the air at the front as it propagates. Such an uplifting leads to a trigger of convection. However, one must realize that a shift of air along with its propagation does not necessarily lead to an uplifting, and even if it may happen, it would not far exceed a depth of the cold pool itself. Thus, the uplifting can never be anything vigorous. Its thermodynamic characteristics do help much either for inducing convection. The cold-pool air is rather under rapid recovering process before it can induce convection under a simple parcel-lifting argument. The most likely reason that the cold pool may induce convection is its gust winds that may encounter an air mass from an opposite direction. This induces a strong convergence, also leading to a strong uplifting. This is an argument essentially developed by Moncrieff and Liu (1999). As a whole, in attempting a statistical description of boundary-layer processes, the cold pool is essentially nothing other than an additional contribution to a TKE (turbulent kinetic energy) budget. Significance of trigger of convection by cold pool in context of convection parameterization must also be seen with much caution. Against a common misunderstanding, current convection parameterization is not designed to describe a trigger process of individual convection. In this respect, process studies on cold pool do not contribute to improvements of convection parameterization until a well-defined parameterization formulation for individual convection processes is developed. Even before then a question should also be posed whether such a development is necessary. Under a current mass-flux convection parameterization, a more important process to consider is re-evaporative cooling of detrained cloudy air, which may also be associated with downdraft, possibly further leading to a generation of a cold pool. Yano and Plant (2012) suggest, from a point of view of the convective-energy cycle, what follows would be far less important than the fact the re-evaporation induces a generation of convective kinetic energy (though it may initially be considered TKE). Both well-focused convective process studies as well as convection parameterization formulation would be much needed.

Yano, Jun-Ichi

2014-05-01

336

Cold sea survival.  

NASA Technical Reports Server (NTRS)

Two prototype three-man life rafts were evaluated during the winter months in Arctic waters off Kodiak Island, Alaska, to assess potential survival problems and determine tolerance limits. Each raft incorporated thermal characteristics specifically designed for cold water. Water and air temperatures varied from 0 to +2 C and -5 to +4 C respectively. All subjects were removed upon reaching subjective tolerance. The results showed that none of the clothing assemblies was adequate to maintain a person in comfort even with dry boarding. No significant biochemical shifts in the blood or urine were found. The TUL raft was found to be superior in its thermal characteristics and afforded better subject protection. General tolerance for cold water immersion, wet and dry, and cold water raft exposures are depicted graphically, based on previously reported data.

Veghte, J. H.

1972-01-01

337

Acral coldness in migraineurs.  

PubMed

In search for new biomarkers of vascular disturbances accompanying migraine, we compared the facial and hand skin temperatures in 41 women, including 12 migraine patients during the headache-free period and 29 healthy controls. Compared to the controls, the acral skin temperatures were lower in migraineurs, especially in those with right-sided headache. Our findings suggest that migraine is associated with a peripheral coldness possibly due to abnormal autonomic vascular control. The cold nose and hands may represent easily assessable biomarkers of these disorders. PMID:24080404

Zaproudina, Nina; Lipponen, Jukka A; Karjalainen, Pasi A; Kamshilin, Alexei A; Giniatullin, Rashid; Närhi, Matti

2014-02-01

338

Cold Dark Matter  

NASA Astrophysics Data System (ADS)

Motivated by inflation, the theory of big-bang nucleosynthesis, and the quest for a deeper understanding of fundamental forces and particles, a paradigm for the development of structure in the universe has evolved. It holds that most of the matter exists in the form of slowly moving elementary particles left over from the earliest moments--cold dark matter-and that the small density inhomogeneities that seed structure formation arose from quantum fluctuations around 10-34 seconds after the big bang. A flood of observations, from determinations of the Hubble constant to measurements of the anisotropy of cosmic background radiation, are now testing the cold dark matter paradigm.

Dodelson, Scott; Gates, Evalyn I.; Turner, Michael S.

1996-10-01

339

Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys  

Microsoft Academic Search

Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in

D. H. Carter; A. C. McGeorge; L. A. Jacobson; P. W. Stanek

1995-01-01

340

Rapid machining of hardened AISI H13 and D2 moulds, dies and press tools  

Microsoft Academic Search

Tools and dies for the forging, die casting and plastics moulding industries are commonly made from AISI H13, heat treated to 48–52 HRC, while the press tool sector predominantly uses AISI D2 at a significantly higher hardness of 60–62 HRC. Over the last 10 years, the introduction of high speed end milling has enabled the direct manufacture of prismatic components

Helen Coldwell; Richard Woods; Martin Paul; Philip Koshy; Richard Dewes; David Aspinwall

2003-01-01

341

Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys  

SciTech Connect

Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which appeared to separate from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatically pressing at 550 C for one hour at 30,000 psi argon pressure. Samples of HIP material were solution treated at 550 C for one hour, followed by a water quench. Aging temperatures were 150, 175, 200 and 225 C for times ranging from one half hour to 65 hours. Hardness measurements were made using a diamond pyramid indenter with a load of 1 kg. Results indicate that peak hardness was reached in 36--40 hours at 175 C and 12--16 hours at 200 C aging temperature, relatively independent of alloy composition.

Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

1995-07-01

342

Freezing Characteristics of Molding Sand with Water by Cold Air Flow for Freeze Mold  

NASA Astrophysics Data System (ADS)

This paper reports the freezing characteristics of sand molded with "the freeze mold method". The freeze mold method is the casting process where little water is added to cast sand then they are frozen and become harden as a mold. Instead of using organic hardener, this molding technology possibly reduces resources and environment loading. We aimed at the practical application of the freeze mold method and chose cold airflow as the medium taking heat away from the mold. At first the sand with water was filled into a rectangular container that is the test section. Then cold air flowed into the container. Consequently, the mold was cooled and frozen by the cold airflow. The freezing behavior of the sample by cold airflow was investigated experimentally under the conditions of added water amount, superficial velocity, inflow air temperature and fixed bed height. As a result, the freezing completion time becomes long as the added water amount increases. However, an increase in the added water amount doesn't influence the pressure loss of the test section so much. Moreover, the empirical equation was derived to predict the freezing completion time.

Horibe, Akihiko; Inaba, Hideo; Haruki, Naoto; Miyagawa, Yasunori

343

Contact allergy to trimethylolpropane triacrylate (TMPTA) in an aziridine plastic hardener.  

PubMed

4 workers developed hand and face dermatitis when exposed to a floor top coat. This contained a polyurethane and a polyfunctional aziridine hardener and additives. The aziridine hardener was made by reacting propyleneimine with a polyfunctional acrylate, trimethylolpropane triacrylate (TMPTA). All 4 reacted to the hardener and to TMPTA, which is present in excess. 2 of them also reacted to pentaerythritol triacrylate (PETA), which can be used in the production of aziridine hardeners. TMPTA and PETA cross-react, and are known sensitizers in UV-hardening acrylates. The present finding shows that well-known sensitizers can be found in hidden sources when used in a quite different chemical process. PMID:6221863

Dahlquist, I; Fregert, S; Trulson, L

1983-03-01

344

A micro-mechanical evaluation of the effects of die hardener on die stone.  

PubMed

The purpose of this study was to investigate the properties of a die hardener penetrated layer and evaluate its protective effects on the surface of die stone. A commercial die hardener (PDQ die hardener, Whipmix corp., USA) was tested on a die stone (GC Fujirock EP die stone, GC Europe, Belgium) and a dental plaster (Dental Stone, United States Gypsum Company, USA). Nanoindentation and micro-scratch tests were performed on both coated and uncoated specimens. The scratch damage was observed by SEM and the penetration depth of die hardener was detected by the affiliated EDX. Upon drying, the die hardener penetrated into the die stone to a depth of 3-5 microm, and deposited a thin film on the surface of die stone. Although the die hardener penetrated layer did not show improved mechanical properties, the die hardener film on the surface did protect the specimens from abrasion damage. PMID:20657152

He, Li-Hong; van Vuuren, Ludwig Jansen; Planitz, Nina; Swain, Michael V

2010-08-01

345

Titanium Cold Spray Coatings  

NASA Astrophysics Data System (ADS)

Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical properties similar to a traditional bulk material. Vickers hardness testing and nanoindentation were used as micro-and nano-scale measurement techniques to characterize the mechanical properties of titanium coatings, deposited at different deposition conditions, and bulk Ti. The mechanical properties of bulk titanium and titanium coatings were measured over a range of length scales, with the indentation size effect examined with Meyer's law. Hardness measurements are shown to be affected by material porosity, microstructure and coating particle bonding mechanism. Hard-ness measurements showed that Ti coatings deposited at higher gas pressures and temperatures demonstrate an indentation load response similar to bulk Ti. Key words: titanium, cold spray, Vickers hardness, nanoindentation, indentation size effect, microstructure, mechanical properties

Ajaja, Jihane; Goldbaum, Dina; Chromik, Richard; Yue, Stephen; Rezaeian, Ahmad; Wong, Wilson; Irissou, Eric; Legoux, Jean-Gabriel

346

Cold spray nozzle design  

DOEpatents

A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

Haynes, Jeffrey D. (Stuart, FL) [Stuart, FL; Sanders, Stuart A. (Palm Beach Gardens, FL) [Palm Beach Gardens, FL

2009-06-09

347

Tumor Cold Ischemia  

Cancer.gov

In a recently published manuscript in the journal of Molecular and Cellular Proteomics, researchers from the National Cancer Institutes (NCI) Clinical Proteomic Tumor Analysis Consortium (CPTAC) investigated the effect of cold ischemia on the proteome of fresh frozen tumors.

348

5 Ultra Cold Neutrons  

Microsoft Academic Search

At the Paul Scherrer Institut (PSI) a new source of ultra cold neutrons (UCN) will be con- structed with the goal to improve the sensitivity to the neutron electric dipole moment (nEDM), which is sensitive to possible contributions from new physics. In addition the neu- tron decay parameters such as its life time may be studied more accurately. Presently, we

P. Fierlinger; S. Heule; U. Straumann

349

Cold Facts about Viruses.  

ERIC Educational Resources Information Center

Provides ways for students to demonstrate their understanding of scientific concepts and skills. Describes a mini-unit around the cold in which students can relate humans to viruses. Includes activities and a modified simulation that provides questions to guide students. Discusses ways that allows students to apply prior knowledge, take ownership…

Pea, Celeste; Sterling, Donna R.

2002-01-01

350

Cold War Propaganda.  

ERIC Educational Resources Information Center

Briefly discusses the development of Cold War propaganda in the United States, Canada, and the USSR after 1947. Presents two movie reviews and a Canadian magazine advertisement of the period which illustrate the harshness of propaganda used by both sides in the immediate postwar years. (GEA)

Bennett, Paul W.

1988-01-01

351

Cold Injury -- Frostbite.  

National Technical Information Service (NTIS)

There is no good way to treat a frostbitten extremity. At best, the physican currently can only avoid additional damage by overly vigorous treatment. In civilian practice the problem is of limited importance occurring primarily in those exposed to cold wh...

1982-01-01

352

Koldstartsanalyse. (Cold start analysis).  

National Technical Information Service (NTIS)

During the period in which a petrol-driven private car is driven with a cold engine, it uses a richer petrol/air mixture in order to overcome carburation difficulties in the inlet manifold. This results in higher emission. With or without catalytic conver...

H. C. Thorsen H. Bendtsen

1994-01-01

353

Catching a Cold  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about infectious disease. The probe is designed to find out whether students use the germ theory to explain what causes an infectious disease like the common cold. This free selection includes the Preface, Introduction, Table of Contents, and the Index.

Tugel, Joyce; Keeley, Page

2009-03-01

354

Evaluation of Electromagnetic Inspection of Hardened Depth of Spheroidal Graphite Cast Iron Using 3-D Nonlinear FEM  

Microsoft Academic Search

The inspection of the hardened depth of surface hardening spheroidal graphite cast iron is important in the maintenance of various mechanical parts, etc. There is a difference of the electromagnetic property in the layers with and without hardening. Therefore, the evaluation of the hardened depth is possible by detecting the difference of the electromagnetic characteristic. In this paper, the electromagnetic

Yuji Gotoh; Nobuya Sasaguri; Norio Takahashi

2010-01-01

355

Springback investigation of anisotropic aluminum alloy sheet with a mixed hardening rule and Barlat yield criteria in sheet metal forming  

Microsoft Academic Search

A mixed hardening model has been implemented based on Lemaitre and Chaboche non-linear kinematic hardening theory to consider cyclic behavior and the Bauschinger effect. The Chaboche isotropic hardening theory is incorporated into the non-linear kinematic hardening model to introduce a surface of nonhardening in the plastic strain space. The bending and reverse bending case study has verified the effectiveness of

Bingtao Tang; Xiaoyang Lu; Zhaoqing Wang; Zhen Zhao

2010-01-01

356

Proposal of Electromagnetic Inspection Method of Hardened Depth of Steel Using 3-D Nonlinear FEM Taking Account of Hysteresis  

Microsoft Academic Search

The inspection of the hardened depth of surface-hardening steel is important in the maintenance of various mechanical parts, and for other purposes as well. There is a difference in the electromagnetic properties in the layers with and without hardening. Therefore, the evaluation of the hardened depth is possible by detecting the difference in the electromagnetic characteristics. In this paper, the

Y. Gotoh; K. Sakurai; N. Takaoka; Y. Misaka; K. Kawasaki; N. Takahashi

2011-01-01

357

Origin of the Cosmic-Ray Spectral Hardening  

NASA Astrophysics Data System (ADS)

Recent data from ATIC, CREAM, and PAMELA indicate that the cosmic-ray energy spectra of protons and nuclei exhibit a remarkable hardening at energies above 100 GeV nucleon-1. We propose that the hardening is an interstellar propagation effect that originates from a spatial change of the cosmic-ray transport properties in different regions of the Galaxy. The key hypothesis is that the diffusion coefficient is not separable into energy and space variables as usually assumed. Under this scenario, we can reproduce the observational data well. Our model has several implications for cosmic-ray acceleration/propagation physics and can be tested by ongoing experiments such as the Alpha Magnetic Spectrometer or Fermi-LAT.

Tomassetti, Nicola

2012-06-01

358

Radiation-hardened microcomputers for robotics and teleoperated systems  

SciTech Connect

Future applications of robots for Environmental Restoration and Waste Management will require radiation-hardened high-performance 32-bit microcomputers for advanced control and sensory integration. With the winding down of many programs sponsored by the U.S. Department of Defense, it is important to select carefully microprocessors for projects that will mature (or will require continued support) several years in the future. Other studies have examined a broad range of radiation-hardened microprocessors available. However, at present there are only six candidate rad-hard 32-bit processors that should be considered for long-range planning for high-performance systems. For U.S. Department of Energy applications, it is also important to consider efforts at standardization that require the use of the VxWorks operating system and hardware based on the VMEbus.

Sias, F.R. Jr. (Clemson Univ., SC (United States)); Tulenko, J.S. (Univ. of Florida, Gainesville, FL (United States))

1993-01-01

359

Stress and Distortion Evolution During Induction Case Hardening of Tube  

NASA Astrophysics Data System (ADS)

Simulation of stresses during heat treatment relates usually to furnace heating. Induction heating provides a very different evolution of temperature in the part and therefore different stresses. This may be positive for service properties or negative, reducing component strength or even causing cracks. A method of coupled simulation between electromagnetic, thermal, structural, stress, and deformation phenomena during induction tube hardening is described. Commercial software package ELTA is used to calculate the power density distribution in the load resulting from the induction heating process. The program DANTE is used to predict temperature distribution, phase transformations, stress state, and deformation during heating and quenching. Analyses of stress and deformation evolution were made on a simple case of induction hardening of external (1st case) and internal (2nd case) surfaces of a thick-walled tubular body.

Nemkov, Valentin; Goldstein, Robert; Jackowski, John; Ferguson, Lynn; Li, Zhichao

2013-07-01

360

Hardening electronic devices against very high total dose radiation environments  

NASA Technical Reports Server (NTRS)

The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.

1972-01-01

361

Cold Injury of Amputated Digits.  

National Technical Information Service (NTIS)

Patients who acquired an upper extremity nerve injury often complain about cold intolerance, reduced sensitivity and decreased task performance. This study tried to quantify these complaints and look in more detail at the thermal reaction to local cold ex...

U. Ahcan B. Luzar F. Bajrovic I. Mekjavic

2005-01-01

362

PHEV Cold Start Emissions Management.  

National Technical Information Service (NTIS)

Plug-in hybrid electric vehicles (PHEV) operate predominantly as electric vehicles (EV) with intermittent assist from the engine. As a consequence, the engine can be subjected to multiple cold start events. These cold start events have a significant impac...

2013-01-01

363

Protecting Workers from Cold Stress  

MedlinePLUS

... agriculture and construction. Common Types of Cold Stress Hypothermia • Normal body temperature (98.6°F) drops to ... When a Worker Suffers from Cold Stress For Hypothermia: • Call 911 immediately in an emergency. • To prevent ...

364

Wear and corrosion resistance of laser surface hardened structural steel  

Microsoft Academic Search

CO2 laser surface treatment in solid state has been performed on a CK60 structural steel. The laser energy density was lower than the melting threshold and only caused surface hardening. The observed heat affected zone (HAZ) ranged in depths of 50–430 ?m. Microstructure of the HAZ was composed of needle, fine-grained martensite and small amount of pearlite and retained austenite.

D. I Pantelis; E Bouyiouri; N Kouloumbi; P Vassiliou; A Koutsomichalis

2002-01-01

365

Laser shock hardening of weld zones in aluminum alloys  

Microsoft Academic Search

The feasibility of using a high energy, pulsed laser beam to shock-harden weld zones in 5086-H32 and 6061-T6 aluminum sheet\\u000a was investigated. The tensile strength, hardness, and microstructure of samples 0.3 cm thick were studied before and after\\u000a laser shocking. After laser shocking, the tensile yield strength of 5086-H32 was raised to the bulk level and the yield strength\\u000a of

Allan H. Clauer; Barry P. Fairand; Ben A. Wilcox

1977-01-01

366

Micromachining of hardened Portland cement pastes using femtosecond laser pulses  

Microsoft Academic Search

Femtosecond laser pulses (30 fs in length) of various energies were utilised for production of single and multiple overlapping\\u000a ablation sites on flat polished surfaces of hardened Portland cement pastes. In order to assess the sizes of the ablation\\u000a sites and possible subsurface laser-induced damage, the ablation sites were investigated using environmental scanning electron\\u000a microscopy (ESEM) – both from normal top–down

P. Trtik; C. P. Hauri

2007-01-01

367

The process simulation of virtual laser surface hardening  

Microsoft Academic Search

This paper focuses on solving the bottleneck problem-process simulation in virtual manufacture (VM), a solution of whole process\\u000a simulation including geometrical aspect and physical aspect is put forward in the domain of laser surface hardening. For the\\u000a difference of mechanisms among the different laser machining modes, the architecture integrated with the common and the distinction\\u000a is constructed for the whole

Taohong Zhang; Tianyuan Xiao; Bingru Yang

2008-01-01

368

Laser transformation hardening of precision V-slide way  

Microsoft Academic Search

The results of the study of the application of laser transformation hardening (LTH) on the precision slide ways and some specimens of 20, 45, GCr15, 18Cr2Ni4WA, or other steels by a 1KW transverse CO2 laser are presented. It is concluded that the LTH can meet all the requirements, such as the case hardness, case depth, distortion allowance, wear resistance, and

G. Zhang; Q. Yang; Y. Wu

1986-01-01

369

CHIP MORPHOLOGY CHARACTERIZATION AND MODELING IN MACHINING HARDENED 52100 STEELS  

Microsoft Academic Search

Hard machining is attracting more and more attention as an alternative to grinding in finish machining some hardened steels. The saw-toothed chips formed in hard machining have their own unique characteristics. The saw-toothed chip morphology is of great interest since the understanding of the saw-toothed chip morphology and its evolution in machining helps unveil hard machining chip formation mechanisms as

Mason D. Morehead; Yong Huang; Jian Luo

2007-01-01

370

Design of a hardened fast bipolar monolithic Charge Sensitive Preamplifier  

Microsoft Academic Search

For implementation of a high-speed, radiation hardened, Charge Sensitive Preamplifier (CSP) in the monolithic 2 ?m BiCMOS technology (called HF2CMOS), the performance of the available NPN and PNP transistors were measured, before and after neutron irradiation. Also monolithic CSPs, realized with the same technology, were irradiated and investigated. The neutron irradiation effect on the base spreading resistance (rbb') of the

A. Baschirotto; R. Castello; G. Pessina; P. G. Rancoita; M. Redaelli; A. Seidman; A. Gola

1995-01-01

371

Effects of residual stress on irradiation hardening in stainless steels  

Microsoft Academic Search

Effects of residual stress on irradiation hardening were studied in advance for predicting irradiation assisted stress corrosion cracking. The specimens of SUS316 and SUS316L with several % plastic strains, which correspond to weld residual stress, were prepared by bending and keeping deformation under irradiation. Ion irradiations of 12MeV Ni3+ were performed at 330, 400 and 550oC to 45dpa. No bended

N. Okubo; Y. Miwa; K. Kondo; Y. Kaji

2009-01-01

372

Laser hardening of VT6 and VT23 titanium alloys  

NASA Astrophysics Data System (ADS)

The characteristics of the surface hardening of VT6 and VT23 titanium alloys during laser heat treatment and laser boriding are investigated theoretically and experimentally. A model is proposed which describes the kinetics of the alpha+beta - beta transformation and beta phase homogenization under the high heating and cooling rates typical of laser treatments. The possibility of controlling the structure of the fusion zone by varying the parameters of laser boriding is demonstrated.

Gordienko, A. I.; Ivashko, V. V.; Bushik, S. V.

1989-06-01

373

Reduction of metal artifacts: beam hardening and photon starvation effects  

NASA Astrophysics Data System (ADS)

The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang

2014-03-01

374

Work-hardening and effective viscosity in solid beryllium  

SciTech Connect

Results from Hopkinson split-bar, plate-impact, and cylinder deceleration experiments on beryllium are compared with hydrodynamic computer code simulations. By substantially increasing the beryllium work-hardening in the Steinberg-Guinan constitutive model, excellent agreement between the experiments and the calculations is achieved. A model to estimate effective viscosity is also proposed and the resultant calculations are in reasonable agreement with those derived from another model advanced by Asay, Chhabildas and Wise. 12 refs., 5 figs.

Steinberg, D.; Breithaupt, D.; Honodel, C.

1985-06-01

375

Hardening evolution of AZ31B Mg sheet  

Microsoft Academic Search

The monotonic and cyclic mechanical behavior of O-temper AZ31B Mg sheet was measured in large-strain tension\\/compression and simple shear. Metallography, acoustic emission (AE), and texture measurements revealed twinning during in-plane compression and untwinning upon subsequent tension, producing asymmetric yield and hardening evolution. A working model of deformation mechanisms consistent with the results and with the literature was constructed on the

X. Y. Lou; M. Li; R. K. Boger; S. R. Agnew; R. H. Wagoner

2007-01-01

376

Dynamic response of two strain-hardened aluminum alloys  

Microsoft Academic Search

Despite their common usage in armor applications such as lightweight armored vehicles, the dynamic material response of 5083-H131 and 5083-H32 strain-hardened aluminum alloys has not been previously reported in the open literature. Measurement of the dynamic material properties, including the shock Hugoniot equation of state (EOS), provides hydrocode modelers with critical information required for accurate modeling of material response to

J. M. Boteler; D. P. Dandekar

2006-01-01

377

Causes of cleavage on case-hardened gear wheels  

Microsoft Academic Search

1.It was established by methods of macrofractography and microfractography that the typical defects of case-hardened gear wheels, viz., cleavage, are brittle hindered failure originating in the transition zone of the case and spreading from the central part of the fracture.2.The principal cause of cleavage are residual tensile stresses which arise as a result of thermochemical treatment on account of incorrect

S. I. Aksenova; M. A. Balter; I. S. Dukarevich; M. M. Gurarii

1988-01-01

378

Hardening treatment of machine parts with CO2 power lasers  

Microsoft Academic Search

Two technological laser facilities were built at the All-Union Scientific Research Institute of Electrothermal Equipment for hardening machine parts using 1.2 and 2.5 kW CO2 lasers. Both lasers are continuous wave devices with self sustained gas discharge between flat anode and tubular cathode. Each facility includes a Fabry-Perot resonator, a beam transporting and focusing mechanism, a laser power measuring instrument

A. S. Borodachev; M. B. Gutman; G. A. Kuznetsov; L. A. Medvedovskaya; G. K. Rubin

1986-01-01

379

Surface hardening of low-carbon martensitic steels by boronizing  

Microsoft Academic Search

A large group of low-carbon martensitic steels developed recently possesses some advantages that make them widely applicable\\u000a in the industry. The main merit of these steels consists in the possibility of deformation-free quenching in air and welding\\u000a in a nonheat-treated state. These features are accompanied by a deep hardenability and high strength characteristics of the\\u000a products and semiproducts. However, when

A. S. Ivanov; A. N. Sokolov

1998-01-01

380

Hardening and Securing Linux OS Syllabus and Course Outline  

NSDL National Science Digital Library

The Center for Systems Security and Information Assurance (CSSIA) provides this zip file with a course outline and syllabus document for a course on hardening and securing Linux OS. The syllabus is a sample one, which could be adapted to suit any course on this topic. It includes information about the course, required textbook, course goals, outline, classroom policies and grading policies. An additional document with a detailed course outline is also included in the zip file.

2013-07-25

381

Sinter-hardening process applicable to stainless steels  

Microsoft Academic Search

Purpose: of this paper was to describe sintered duplex stainless steels manufactured in sinter-hardening process and its usability in field of stainless steels. Design\\/methodology\\/approach: In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic, ferritic base powders by controlled addition of alloying elements, such as Cr, Ni, Mo and Cu. In the studies apart from the

L. A. Dobrza?ski a; Z. Brytan; M. Rosso

382

Optically-triggered hardened thyristors for firing set circuits  

SciTech Connect

Silicon thyristors, directly triggered by light, are used to switch pulsed currents in firing set circuits. They are hardened to transient ionizing radiation by the addition of a reverse-biased compensating photodiode connected to the gate of the thyristor. Tests of these compensated devices show radiation-induced switching is completely inhibited in excess of 1.4 {times} 10{sup 9} rad (Si)/sec. 2 refs., 5 figs.

Carson, R.F.; Knauss, G.L.

1990-01-01

383

Hardened tuned-wall plastic radomes for military radars  

Microsoft Academic Search

XP (stretched polypropylene) film is perhaps the most effective material for construction of hardened dielectric walls. It has excellent fragment-defeat properties, a low relative dielectric constant (2.3) and a very low loss tangent (0.005). For low-loss materials, reflection losses are determined by the dielectric constant and absorption losses by the loss tangent. A perfect radome material would have a dielectric

J. J. Prifti; E. Deluca; A. L. Alesi

1976-01-01

384

Surface modification on PMMA : PVDF polyblend: hardening under chemical environment  

Microsoft Academic Search

The influence of chemical environment on polymers include the surface alteration as well as other deep modifications in surface\\u000a layers. The surface hardening, as an effect of organic liquids on poly(methyl methacrylate): poly(vinylidene fluoride) (PMMA:\\u000a PVDF), which is one of the few known miscible blends, has been detected using microhardness testing. Organic liquids like\\u000a acetone, toluene, xylene and benzene were

R. Bajpai; V. Mishra; Pragyesh Agrawal; S. C. Datt

2002-01-01

385

Strain hardening of polymer glasses: Entanglements, energetics, and plasticity  

Microsoft Academic Search

Simulations are used to examine the microscopic origins of strain hardening\\u000ain polymer glasses. While stress-strain curves for a wide range of temperature\\u000acan be fit to the functional form predicted by entropic network models, many\\u000aother results are fundamentally inconsistent with the physical picture\\u000aunderlying these models. Stresses are too large to be entropic and have the\\u000awrong trend

Robert S. Hoyand; Mark O. Robbins

2008-01-01

386

Sequential circuit design for radiation hardened multiple voltage integrated circuits  

DOEpatents

The present invention includes a radiation hardened sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.

Clark, Lawrence T. (Phoenix, AZ); McIver, III, John K. (Albuquerque, NM)

2009-11-24

387

Influence of hardening and surface modification of endourological wires on corrosion resistance.  

PubMed

Guide wires with suitable functional characteristics are of crucial importance for proper urological treatment. This study presents an analysis of the effect of work hardening taking place in the process of wire cold drawing and the effect of surface modification by means of electrochemical polishing and chemical passivation on the resistance of wires made of X10CrNi18-8 steel used in urology. Corrosion resistance was evaluated on the grounds of the registered anodic polarisation curves by means of potentiodynamic method. The tests were made in solution simulating human urine. Anodic polarisation curves were presented for selected wire diameters. Mechanical properties were tested in a static uniaxial tensile test. The course of flow curve as well as mathematical form of flow stress function were determined. Curves presenting the relation of polarisation resistance as a function of strain applied in the drawing process are given. The tests carried out show that surface modification by means of electrochemical polishing and then chemical passivation of wires used in endourological treatment is fundamental. PMID:23140197

Walke, Witold; Przondziono, Joanna

2012-01-01

388

Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

Wagner, John A.

1989-01-01

389

[Structural and functional reorganization of photosynthetic apparatus in cold adaptation of wheat plants].  

PubMed

The structural and functional characteristics of the photosynthetic apparatus (PSA) and the cold resistance of wheat seedlings were studied during low-temperature adaptation. It has been established that large chloroplasts with thylakoid system of "sun type" forme in the mesophyll cells in the early hours of plants hardening. At the same time the functional reorganization of the PSA in the leaves of wheat occurs: content of pigments changes, stabilization of the pigment-protein complexes is observed, non-photochemical quenching of excess energy increases. The stabilization of photosynthesis during cold adaptation occurs due to structural and functional reorganization of the PSA. It is assumed that the reorganization of the PSA is a prerequisite for formation of increased cold resistance of leaf cells, and this, along with other physiological and biochemical changes occurring in cells and tissues of plants, allows the plants to survive in chilling. PMID:23461037

Venzhik, Ju V; Titov, D F; Talanova, V V; Miroslavov, E D; Koteeva, N K

2012-01-01

390

Hardening and welding with high-power diode lasers  

NASA Astrophysics Data System (ADS)

Commercially available high power diode lasers (HPDLs) with output powers of up to 6 kW have been recognized as an interesting tool for industrial applications. In certain fields of application they offer many advantages over Nd:YAG and CO2 lasers because of their low maintenance, compact design and low capital costs. Examples of successful industrial implementation of HPDLs include plastic welding, surface hardening and heat conduction welding of stainless steel and aluminum. The joining of plastics with an HPDL offers the advantages of producing a weld seam with high strength, high consistency and superior appearance. One example is the keyless entry system introduced with the Mercedes E-class where the microelectronic circuits are embedded in a plastic housing. Other applications include instrument panels, cell phones, headlights and tail lights. Applications in the field of surface treatment of metals profit from the HPDL's inherent line-shaped focus and the homogeneous intensity distribution across this focus. An HPDL system is used within the industry to harden rails for coordinate measurement machines. This system contains a customized zoom optic to focus the laser light onto the rails. With the addition of a temperature control, even complex shapes can be hardened with a constant depth and minimum distortion.

Ehlers, Bodo; Herfurth, Hans-Joachim; Heinemann, Stefan

2000-03-01

391

Remedies for Common Cold Symptoms  

PubMed Central

Individuals suffering from intolerable symptoms of the common cold can now be advised of safe and effective products for symptomatic relief. This article describes and discusses four categories of drugs used to treat the common cold. To simplify the product selection process for family physicians, suggestions are included for possible ingredients for treatments of specific cold symptoms.

Miller, Penny F.

1991-01-01

392

Effect of Variation in Matrix Constitution on the Work Hardening Behavior of a Peak Age Hardened SiC Reinforced Aluminum Based Metal-Matrix Composite  

Microsoft Academic Search

An understanding of the work hardening behavior of particulate reinforced metal -matrix composites is crucial in optimizing the parameters for deformation processing of these materials. In the case of particulate reinforced composites with an age hardenable aluminum alloy matrix, the microstructure and mechanical properties can be altered by a suitable aging treatment as well as by changing the content of

M. Manoharan; M. Gupta

1998-01-01

393

An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface-Hardened Stainless Steel  

NASA Astrophysics Data System (ADS)

A surface hardening technique called "interstitial hardening" is commercially available, whereby interstitial carbon atoms are introduced into stainless steel surfaces without the formation of carbides. Surface hardening of machine elements such as impellors or fasteners would improve performance regarding cavitation and galling resistance, and has intensified interest in this process. However, there remains a need to characterize and validate the specific performance characteristics of the hardened materials. This paper describes experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using carbon as the interstitial atom. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to determine the breakdown potential in 3.5 wt.% NaCl solution to identify the most promising method. The hardness and thickness of the surface-hardened layer is characterized and compared using metallography and microhardness profiling. Corrosion fatigue and slow strain rate testing of untreated, hardened, and damaged, hardened surfaces exposed to ASTM seawater is conducted. Finally, critical galling stresses are determined and compared. Post-test examination of damage attempts to identify mechanisms of material failure and characterize how corrosion-assisted cracks initiate and grow in surface-hardened materials.

Jones, Jennifer L.; Koul, Michelle G.; Schubbe, Joel J.

2014-03-01

394

An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface-Hardened Stainless Steel  

NASA Astrophysics Data System (ADS)

A surface hardening technique called "interstitial hardening" is commercially available, whereby interstitial carbon atoms are introduced into stainless steel surfaces without the formation of carbides. Surface hardening of machine elements such as impellors or fasteners would improve performance regarding cavitation and galling resistance, and has intensified interest in this process. However, there remains a need to characterize and validate the specific performance characteristics of the hardened materials. This paper describes experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using carbon as the interstitial atom. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to determine the breakdown potential in 3.5 wt.% NaCl solution to identify the most promising method. The hardness and thickness of the surface-hardened layer is characterized and compared using metallography and microhardness profiling. Corrosion fatigue and slow strain rate testing of untreated, hardened, and damaged, hardened surfaces exposed to ASTM seawater is conducted. Finally, critical galling stresses are determined and compared. Post-test examination of damage attempts to identify mechanisms of material failure and characterize how corrosion-assisted cracks initiate and grow in surface-hardened materials.

Jones, Jennifer L.; Koul, Michelle G.; Schubbe, Joel J.

2014-06-01

395

Performance of radiation hardening techniques under voltage and temperature variations  

NASA Astrophysics Data System (ADS)

The effectiveness of the techniques to mitigate radiation particle hits in digital CMOS circuits has been mainly studied under a given set of environmental conditions. This paper will explicitly analyze, how the performance of two selected radiation hardening techniques, namely transistor sizing and stack separation, varies with temperature and supply voltage. Our target is an inverter circuit in UMC90 bulk CMOS technology, instances of which have been hardened against charges of 300fC and 450fC using either of the two techniques under investigation. In a Spice simulation we apply particle hits to these circuits through double-exponential current pulses of the respective charge. We study the effect of these pulses in a temperature range from - 55 C to +175 C and a supply voltage of 0.65 to 1.2V (nominal 1V) at the output of a (unhardened) buffer that has been connected as a load. For the hardening by sizing we observe proper operation in the range from 1.2V to 900mV, while for lower supply we observe full swing pulses of increasing magnitude when the respective maximum charge is applied. The influence of temperature turns out to be minor. For the stack separation approach the observation is similar, however, the circuit starts glitching only at 750mV. Our study allows the following conclusions: (i) The effectiveness of the hardening approaches strongly depends on the supply voltage, and moderately on temperature. (ii) As expected, low voltage and high temperature represent the worst case for rad-hard sizing. Stack separation, on the other hand, unexpectedly shows a stronger and more complicated temperature dependence. (ii) For voltages below approx. 90% of nominal the hardening by sizing fails, when designed for nominal voltage and room temperature. The approach can be enhanced to survive this worst case by increasing the sizing factor further by more than 3 times. (iv) The stack separation only fails for voltages below approx. 75% of nominal, but there is n- simple remedy to make it reliable for a larger range. This must be considered when judging the appropriateness of this method for a given purpose. Also it turned out that once it fails, the resulting SET pulse has considerable length.

Veeravalli, Varadan Savulimedu; Steininger, Andreas

396

Structural study of oriental lacquer films during the hardening process.  

PubMed

Oriental lacquer is the natural resin obtained by tapping lac trees. It hardens into a tough and insoluble film. The extreme hardness and insolubility are some of the most important functions, which are required for industrial coating materials. In this study, two kinds of oriental lacquer films, traditionally named Kiurushi (raw urushi) and Kuromeurushi produced by two different pretreatments, were analyzed during hardening with Fourier transform infrared spectroscopy (FT-IR), thermogravimetry/differential thermal analysis-mass spectrometry (TG/DTA-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to investigate their functional expression process. Typical functional groups of the lacquer films were detected by FT-IR. The TG/DTA-MS curves clarified that the thermal degradation of the lacquer films gradually began at around 200 degrees C, and reached the fastest rate at 400-500 degrees C. Apparently, FT-IR and TG/DTA-MS could not reveal any difference between the films. On the other hand, Py-GC/MS revealed differences between the films in the peak area ratios of 3-pentadecenylcatechol to 3-pentadecylcatechol and 3-pentadecadienylcatechol to 3-pentadecylcatechol. The ratios of Kiurushi lacquer film were higher than those of Kuromeurushi lacquer film. Both ratios, furthermore, decreased during hardening due to polymerization of the alkenylcatechols into an urushiol polymer skeleton comprising nucleus-side chain and side chain-side chain cross-linkages with 3-pentadecylcatechol at the terminal. The present results suggest that the reaction rate of these cross-linkages in Kuromeurushi lacquer film is faster than that in Kiurushi lacquer film. A good correlation was found between the peak area ratios obtained by Py-GC/MS and hardness obtained by pencil hardening testing. Oriental lacquer expresses the functions - an extreme hardness and insolubility - accelerating the nucleus-side chain and side chain-side chain cross-linkages. Furthermore, it has become clear that the traditional treatments called Nayashi and Kurome effectively accelerate the hardening rate by activating the cross-linkages. PMID:18970743

Niimura, Noriyasu; Miyakoshi, Tetsuo

2006-08-15

397

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

Grundy, Brian R. (Greensburg, PA)

1981-01-01

398

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

Grundy, B.R.

1981-09-29

399

WISPy cold dark matter  

NASA Astrophysics Data System (ADS)

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches — exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques — can probe large parts of this parameter space in the foreseeable future.

Arias, Paola; Cadamuro, Davide; Goodsell, Mark; Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

2012-06-01

400

Clumpy cold dark matter  

NASA Technical Reports Server (NTRS)

A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

Silk, Joseph; Stebbins, Albert

1993-01-01

401

Cold nuclear fusion  

NASA Astrophysics Data System (ADS)

Recent accelerator experiments on fusion of various elements have clearly demonstrated that the effective cross-sections of these reactions depend on what material the target particle is placed in. In these experiments, there was a significant increase in the probability of interaction when target nuclei are imbedded in a conducting crystal or are a part of it. These experiments open a new perspective on the problem of so-called cold nuclear fusion.

Tsyganov, E. N.

2012-02-01

402

Cold nuclear fusion  

Microsoft Academic Search

The possibility that negative muons could catalyze nuclear fusion was suggested on theoretical grounds by F.C. Frank and A.D. Sakharov in the late 1940s; the first experimental observations of the process followed serendipitously a decade later, in experiments at Berkeley by L.W. Alvarez. The fastest mechanism for muon-catalyzed, or 'cold' fusion, was suggested by Vesman (1967); it depends on a

Johann Rafelski; Steven E. Jones

1987-01-01

403

Teachers Debate Cold Fusion  

NASA Astrophysics Data System (ADS)

What follows is a collection of messages about cold fusion from teachers. The messages were posted on the internet discussion list, Phys-L, or were sent to me in private. They illustrate a wide range of opinion. Phys-L is a list dedicated to learning and teaching physics with 700 subscribers from over 35 countries, the majority of whom are physics educators. <>.

Kowalski, Ludwik

2005-12-01

404

Effects of cold work and phosphorous on the ductile to brittle transition behavior of F82H steels  

NASA Astrophysics Data System (ADS)

The effects of cold work and phosphorous on ductile to brittle transition behavior were investigated in order to evaluate the effects of hardening and intergranular degradation on the ductile to brittle transition temperature (DBTT) of F82H steel. Yield strength and ultimate tensile strength are increased by increasing the level of cold work. Phosphorous additions resulted in a small increase in the strength of F82H. The DBTT after cold work is shifted to high temperature and upper shelf energy (USE) is decreased. The shift of DBTT and the reduction of USE increase with the cold work level. F82H as-received and cold worked steel fractured in a cleavage mode at temperatures of lower shelf energy (LSE) region. The DBTT is shifted to higher temperatures with increasing phosphorus additions accompanied by the reduction of the USE. Although the hardening is small, a significant embrittlement was observed in the steels added with phosphorus, which was accompanied by intergranular cracking at temperatures in LSE region.

Kim, Byung Jun; Kasada, Ryuta; Kimura, Akihiko; Tanigawa, Hiroyasu

2011-10-01

405

Effect of Hf on structure and age hardening of Ti-Al-N thin films  

PubMed Central

Protective coatings for high temperature applications, as present e.g. during cutting and milling operations, require excellent mechanical and thermal properties during work load. The Ti1 ? xAlxN system is industrially well acknowledged as it covers some of these requirements, and even exhibits increasing hardness with increasing temperature in its cubic modification, known as age hardening. The thermally activated diffusion at high temperatures however enables for the formation of wurtzite AlN, which causes a rapid reduction of mechanical properties in Ti1 ? xAlxN coatings. The present work investigates the possibility to increase the formation temperature of w-AlN due to Hf alloying up to 10 at.% at the metal sublattice of Ti1 ? xAlxN films. Ab initio predictions on the phase stability and decomposition products of quaternary Ti1 ? x ? yAlxHfyN alloys, as well as the ternary Ti1 ? xAlxN, Hf1 ? xAlxN and Ti1 ? zHfzN systems, facilitate the interpretation of the experimental findings. Vacuum annealing treatments from 600 to 1100 °C indicate that the isostructural decomposition, which is responsible for age hardening, of the Ti1 ? x ? yAlxHfyN films starts at lower temperatures than the ternary Ti1 ? xAlxN coating. However, the formation of a dual phase structure of c-Ti1 ? zHfzN (with z = y/(1 ? x)) and w-AlN is shifted to ~ 200 °C higher temperatures, thus retaining a film hardness of ~ 40 GPa up to ~ 1100 °C, while the Hf free films reach the respective hardness maximum of ~ 38 GPa already at ~ 900 °C. Additional annealing experiments at 850 and 950 °C for 20 h indicate a substantial improvement of the oxidation resistance with increasing amount of Hf in Ti1 ? x ? yAlxHfyN.

Rachbauer, R.; Blutmager, A.; Holec, D.; Mayrhofer, P.H.

2012-01-01

406

Cold Drawn ERW Pipes with Superior Formability,  

National Technical Information Service (NTIS)

Cold drawn ERW pipes have been applied in various fields. Cold drawn pipes show recrystallized microstructures when they are annealed for softening. Cold drawn ERW pipes sometimes show a difficulty in formability during cold working of expanding, swaging ...

T. Adaniya T. Takamura T. Meada F. Nishimura M. Morimoto

1988-01-01

407

Investigation into springback characteristics of two HSS sheets during cold v-bending  

NASA Astrophysics Data System (ADS)

Considering the safety and the light-weight structure, there is an increasing requirement of high strength steel (HSS) sheets in the automotive industry. The high-precise prediction of the springback depends on constitutive equations and their corresponding material parameters. In order to investigate the springback of HSS sheets, DP590 and B280VK, their constitutive behaviors were analyzed based on the sheet tension tests. With respect to the constitutive equation, the Voce model is more proper to two hot-rolled steels, DP590 and B280VK, than the Swift model. Two steels are all saturated hardening, and the degree of hardening decreases with the strain. The cold v-banding tests of two HSS sheets were carried out for evaluation of springback characteristics. Results of v-bending experiments showed that the springback angle increases with the bending along 45°, 90° and 0° to the rolling direction of steel in turn.

Fang, Gang; Gao, Wei-Ran

2013-12-01

408

A rapid cyclic voltammetric method for studying cement factors affecting the corrosion of reinforced concrete  

SciTech Connect

A rapid cyclic voltammetric method for studying the influence of cement factors on the corrosion of embedded iron and steel in hardened cement paste is described. The technique employs a cement electrode'' consisting of an iron or steel wire embedded in a miniature cylinder of hardened cement paste. The rapid cyclic voltammetric method is fast, reproducible, and provides information on the corrosiveness of the pore solution environment surrounding the embedded metal. The usefulness of the method is demonstrated by showing how it can be used to evaluate the threshold chloride content of hardened ordinary portland cement paste at which corrosion begins and by using it to evaluate the relative efficacy of several admixed corrosion inhibitors.

Foulkes, F.R.; McGrath, P. (Univ. of Toronto, Ontario (Canada))

1999-06-01

409

Impacting Behavior of Large Oxidized Copper Particles in Cold Spraying  

NASA Astrophysics Data System (ADS)

In a previous study, it has been experimentally demonstrated that surface oxide films of metallic particles have significant influence on the properties of cold-sprayed coatings. To clearly reveal the underlying mechanism, this study focused further on the effect of particle oxidation on the deposition behavior of oxidized Cu powder. Results show that the presence of the oxide films on the particles' surface can inhibit the plastic deformation of the particles. In addition, results concerning the morphologies and oxygen content of the rebounded particles show that the particles have experienced large plastic deformation that results in the break-up of the oxide films during the impacting process. Correspondingly, the hardness of the coating deposited with the oxidized powder is a little lower than that with the annealed powder because of the inferior plastic deformation and strain-hardening effect.

Yu, Min; Li, Wenya; Guo, Xueping; Liao, Hanlin

2013-03-01

410

Effectiveness of Waterproof, Breathable Handwear in a Cold Environment. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Cooling of the hands has been implicated as a cause for reduced endurance time, loss of manual dexterity and general discomfort during cold exposure. An extended exposure to cold-wet weather can result in rapid cooling of the extremities from the conducti...

T. L. Endrusick W. R. Santee L. A. Blanchard R. R. Gonzalez

1990-01-01

411

A search for the Mpemba effect: When hot water freezes faster then cold water  

Microsoft Academic Search

An explanation for why hot water will sometime freeze more rapidly than cold water is offered. Two specimens of water from the same source will often have different spontaneous freezing temperatures; that is, the temperature at which freezing begins. When both specimens supercool and the spontaneous freezing temperature of the hot water is higher than that of the cold water,

James D. Brownridge

2010-01-01

412

Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash  

DOEpatents

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points. 2 figs.

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1997-10-28

413

Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash  

DOEpatents

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points.

Liskowitz, John W. (Belle Mead, NJ); Wecharatana, Methi (Parsippany, NJ); Jaturapitakkul, Chai (Bangkok, TH); Cerkanowicz, deceased, Anthony E. (late of Livingston, NJ)

1997-01-01

414

Akt activation protects liver cells from apoptosis in rats during acute cold exposure.  

PubMed

Accidental deaths due to exposure to extremely low natural temperature happen every winter. Exposure to extreme cold causes injury of multiple organs. However, early responses of the bodies to acute extreme cold exposure remain incompletely understood. In this study, we found that hepatic glycogen was rapidly reduced in rats exposed to -15°C, and the key enzymes required for glycogenesis were upregulated in the livers of the cold-exposed rats. In line with the rapid consumption of glycogen, acute cold exposure induced a transient elevation of cellular ATP level, which lasted about one hour. The ATP level went back to basal level after two hours of cold exposure. Four hours of cold exposure resulted in cellular ATP depletion and cell apoptosis. The dynamic change of cellular ATP levels was well associated with Akt activation in cold-exposed liver cells. The activation of Akt was required for cold exposure-induced ATP elevation. Blockade of Akt activation diminished the transient increase of intracellular ATP content and exacerbated cell apoptosis during acute cold exposure. These results suggest that Akt activation plays a pivotal role in maintaining cellular bioenergy balance and promoting liver cell survival during acute cold exposure. PMID:23781144

Wang, Jiye; Chen, Yaoming; Zhang, Wenbin; Zheng, Gang; Meng, Shanshan; Che, Honglei; Ke, Tao; Yang, Jingrun; Chen, Jingyuan; Luo, Wenjing

2013-01-01

415

Laser transformation hardening of AISI 440C martensitic stainless steel for higher cavitation erosion resistance  

Microsoft Academic Search

Surface hardening of AISI 440C martensitic stainless steel was achieved by laser transformation hardening (LTH) using a high-power CW Nd:YAG laser. A hardened layer of a few 100 ?m thick, composed of martensite, retained austenite and fine carbides was formed. The microstructure and hardness of the laser-treated layer were dependent on the laser processing parameters, with the hardness values reaching

K. H. Lo; F. T. Cheng; H. C. Man

2003-01-01

416

Microstructure analysis of nodular iron 400-12 after laser surface melt hardening  

Microsoft Academic Search

The application of laser surface melt hardening to nodular iron 400-12 causes the material to undergo microstructural changes. A newly created austenite-ledeburite microstructure with the presence of graphite nodules in the melted zone and a martensite-ferrite microstructure with graphite nodules in the hardened zone have been observed. Microscopy of the hardened zone was used to analyze the occurrence of martensite

Janez Grum; Roman Šturm

1996-01-01

417

Surface hardening of steel by laser and electron beam. (Latest citations from METADEX). Published Search  

SciTech Connect

The bibliography contains citations concerning electron beam hardening of steels and alloys. Among the materials surface hardened are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface hardening treatment is also examined. (Contains a minimum of 93 citations and includes a subject term index and title list.)

Not Available

1994-09-01

418

Wear and friction properties of laser surface hardened En31 steel  

Microsoft Academic Search

The surface of En31 steel was treated by CO2 laser for solid state transformation hardening. The wear and friction characteristics of the treated surfaces were examined and compared with untreated surfaces using the lubricated ring-on-block technique. The microstructures of the laser-hardened tracks and the worn surfaces were studied by SEM. The results indicated that the surface of a single hardened

X. M Zhang; H. C Man; H. D Li

1997-01-01

419

Effect of combined hardening on the structure and properties of high-strength cast iron  

Microsoft Academic Search

Laser hardening was carried out on an LT-I continuous-running CO2-1aser of 1.5 kW. To increase the coefficient of light energy absorption the specimens were covered by a 10% persulfate ammonium coating. The laser hardening regime was selected so that the thickness of the finished layer was 0.5 mm. The paths hardened by laser with a width and spacing of 3

V. V. Belozerov; V. A. Guiva; A. I. Makhatilova; A. V. Radzivonchik; M. L. Turovskii

1990-01-01

420

Sinter-hardening of Ni-Mo pre-alloyed powders with tungsten addition  

Microsoft Academic Search

Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development of sinter-hardening process. The mechanical properties, focusing in particular on hardness and wear resistance, of two different carbon levels pre-alloyed steel powders processed with sinter-hardening method, were described. Microstructure characteristic of produced sinter-hardened Ni-Mo steels with increasing amount of tungsten (from 0 to 0.3%

L. A. Dobrza?ski a; J. Otr?ba; M. Actis Grande; M. Rosso

421

Improved impact toughness of 13Cr martensitic stainless steel hardened by laser  

NASA Astrophysics Data System (ADS)

The impact toughness of AISI 403 martensitic stainless steel plate and laser-hardened specimens tempered at various temperatures were examined. Phosphorus was the primary residual impurity responsible for tempered embrittlement of this alloy. The experimental result also indicated that AISI 403 stainless steel was very sensitive to reverse-temper embrittlement. The improved impact toughness of the laser-hardened specimen was attributed to the refined microstructure in the laser-hardened zone.

Tsay, L. W.; Chang, Y. M.; Torng, S.; Wu, H. C.

2002-08-01

422

Involvement of carbohydrates in the hardening of the zona pellucida of mouse oocytes.  

PubMed

The effect of lectins with different saccharide specificity (ConA, LCA, DBA, WGA and PNA) on enzymatic digestion of the zona pellucida (ZP) of mouse oocytes was studied. All lectins tested, except PNA, induced ZP hardening with different degrees of efficiency. Moreover, extensive ZP digestion with mixed exoglycosidase prevented "spontaneous" ZP hardening. These observations suggest that changes of the carbohydrate moieties can be involved in the hardening of the zona pellucida of mouse oocytes. PMID:1934081

Dolci, S; Bertolani, M V; Canipari, R; De Felici, M

1991-07-01

423

An analysis of grain boundary cohesion in precipitation hardened stainless steel  

Microsoft Academic Search

17-4 precipitation hardened (PH) stainless steel belongs to the family of precipitation hardening martensitic stainless steel (AISI 630), containing 17%Cr, 4%Ni and 4%Cu as the main alloying elements; carbon content in the steel is normally maintained below about 0.05 wt.%. The authors have recently attempted an assessment of 17-4 precipitation hardened martensitic steel in terms of processing steps and heat

R. D. K Misra; R. Rao

1993-01-01

424

Development of a Pressure-Dependent Constitutive Model with Combined Multilinear Kinematic and Isotropic Hardening  

NASA Technical Reports Server (NTRS)

The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.

Allen Phillip A.; Wilson, Christopher D.

2003-01-01

425

Effect of microstructure and hardness on non-proportional cyclic hardening coefficient and predictions  

Microsoft Academic Search

This paper investigates the effects of microstructure and hardness on non-proportional cyclic hardening of metallic materials. Constant amplitude in-phase and 90° out-of-phase strain-controlled axial-torsion cyclic tests were conducted to evaluate the hardening. Tubular specimens made from 1050 steel in normalized, quenched and tempered, and induction hardened conditions as well as 304L stainless steel were used to study the effect of

Nima Shamsaei; Ali Fatemi

2010-01-01

426

Influence of Temperature on Autogenous Deformation and RH-Change in Hardening Cement Paste.  

National Technical Information Service (NTIS)

This report treats the influence of temperature on autogenous deformation and autogenous relative humidity change in hardening cement pastes. The subject is delt with both theoretically and experimentally.

O. M. Jensen

1998-01-01

427

Hardening reactions in a high-gold content ceramo-metal alloy.  

PubMed

A high-gold content ceramo-metal alloy (85 wt% Au, 5 wt% Pd, 5 wt% Pt) was selected for a definitive study of the hardening reactions. Specific points of concern included the hardening phase, hardening mechanism, and reaction kinetics to provide an understanding of the hardness development during the porcelain firing cycle. Contrary to previous reports, it is shown that ordering of a submicron FePt-type intermetallic phase is responsible for the observed aging behavior. Hence, it is concluded that through proper alloy design the hardening reaction can be made insensitive to variation in porcelain firing cycles. PMID:6933181

German, R M

1980-11-01

428

Simulation and measurement of temperature field of nodular cast iron in laser transformation hardening  

NASA Astrophysics Data System (ADS)

In this paper, the temperature field of nodular cast iron in laser transformation hardening was simulated by using ANSYS software and tested with CCD-based colorimetric temperature measurement method. Firstly, the temperature field was calculated, and the width of the hardened track was estimated according to the calculated result. Then, the temperature field was measured in the presented experiments. After comparison of the calculated results to the experimental ones, it was found that the width of the hardened track can be predicted by the measured temperature field, which would help analyse the effect of process parameters and carry out real-time control in laser transformation hardening process.

Hu, Shunxi; Liu, Jichang

2010-11-01

429

Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation  

NASA Technical Reports Server (NTRS)

The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

Miner, R. V.; Castelli, M. G.

1992-01-01

430

Influence of metal acetylacetonates on the rate of hardening of epoxy oligomers by amines  

SciTech Connect

Metal acetylacetonates, M(AA)/sub n/, have various effects on the reactivity of epoxy compositions, but are known mainly as accelerators of hardening of epoxy resins by dicyanodiamide, anhydrides of dicarboxylic acids, and phenols. The substances studied in this paper were ED-22 epoxy-Bisphenol A oligomer having an epoxy equivalent of 194, and acetylacetonates of CoS, NiS , and FeT . Diethylenetriamine (DETA), 4,4'-diaminodiphenylmethane (DAM), and UP-606/2 tris(dimethy-p-aminomethyl) phenol were used as hardeners. The hardening rates of the compositions were studied by measurement of the volume resistivity of the hardening systems and of the gel time.

Nazarova, Z.F.; Evtushenko, G.A.; Palagushkina, L.A.; Artemova, V.V.

1986-05-10

431

Organoapatites: materials for artificial bone. II. Hardening reactions and properties.  

PubMed

This article reports on chemical reactions and the properties they generated in artificial bone materials termed "organoapatites." These materials are synthesized using methodology we reported in the previous article of this series. Two different processes were studied here for the transition from organoapatite particles to implants suitable for the restoration of the skeletal system. One process involved the hardening of powder compacts by beams of blue light derived from a lamp or a laser and the other involved pressure-induced interdiffusion of polymers. In both cases, the hardening reaction involved the formation of a polyion complex between two polyelectrolytes. In the photo-induced reaction an anionic electrolyte polymerizes to form the coulombic network and in the pressure-induced one, pressure forms the complex by interdiffusion of two polyions. Model reactions were studied using various polycations. Based on these results the organoapatite selected for the study was that containing dispersed poly(L-lysine) and sodium acrylate as the anionic monomer. The organomineral particles can be pressed at room temperature into objects of great physical integrity and hydrolytic stability relative to anorganic controls. The remarkable fact about these objects is that intimate molecular dispersion of only 2-3% by weight organic material provides integrity to the mineral network in an aqueous medium and also doubles its tensile strength. This integrity is essentially nonexistent in "anorganic" samples prepared by the same methodology used in organoapatite synthesis. The improvement in properties was most effectively produced by molecular bridges formed by photopolymerization. The photopolymerization leads to the "hardening" of pellets prepared by pressing of organoapatite powders. The reaction was found to be more facile in the microstructure of the organomineral, and it is potentially useful in the surgical application of organoapatites as artificial bone. PMID:8360199

Stupp, S I; Mejicano, G C; Hanson, J A

1993-03-01

432

BUSFET - A Novel Radiation-Hardened SOI Transistor  

SciTech Connect

The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes hardening SOI transistors more challenging than hardening bulk-silicon transistors. Two avenues for hardening the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, we propose a new partially-depleted SOI transistor structure that we call the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU and dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration and the depth of the source. 3-D simulations show that for a doping concentration of 10{sup 18} cm{sup {minus}3} and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3x10{sup 17} cm{sup {minus}3}, a thicker silicon film (300 nm) must be used.

Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.

1999-07-20

433

Radiation-Hardened Software for Space Flight Science Applications  

NASA Astrophysics Data System (ADS)

Hardware faults caused by radiation-induced Single Event Effects (SEEs) are a serious issue in space flight, especially affecting scientific missions in earth orbits crossing the poles or the South Atlantic Anomaly. Traditionally, SEEs are treated as a hardware problem, for example mitigated by radiation-hardened processors and shielding. Rad-hardened processors are expensive, exhibit a decade performance gap compared to COTS technology, have a larger form factor and require more power. Shielding is ineffective for high energy particles and increases launch weight. Hardware approaches cannot dynamically adapt protection levels for different radiation scenarios depending on solar activity and flight phase. Future hardware will exacerbate the problem due to higher chip densities and lower power levels. An alternative approach is to use software to mitigate SEEs. This "Radiation Hardened Software" (RHS) approach has two components: (1) RHS library and application design guidelines To increase robustness, we combine SEE countermeasures in three areas: prevention and detection; recovery; and reconfiguration. Prevention and detection includes an application- and heap-aware memory scanner, and dynamically adapted software Error Correction Codes to handle cache and multi-bit errors. Recovery mechanisms include exception firewalls and transaction-based software design patterns, to minimize data loss. Reconfiguration includes a heap manager to avoid damaged memory areas. (2) Software-based SEE Simulation Probabilistic effects require extensive simulation, with test environments that do not require original flight hardware and can simulate various SEE profiles. We use processor emulation software, interfaced to a debugger, to analyze SEE propagation and optimize RHS mechanisms. The simulator runs unmodified binary flight code, enables injecting randomized transient and permanent memory errors, providing execution traces and precise failure reproduction. The goal of RHS is to verify that effective SEE software countermeasures are implementable at reasonable runtime costs, enabling use of more COTS hardware with significant performance gains for science applications.

Mehlitz, P. C.; Penix, J. J.; Markosian, L. Z.

2005-12-01

434

Review on Cold Spray Process and Technology: Part I—Intellectual Property  

Microsoft Academic Search

The number of research papers as well as of patents and patent applications on cold spray and cold spray related technologies\\u000a has grown exponentially in the current decade. This rapid growth of activity brought a tremendous amount of information on\\u000a this technology in a short period of time. The main motivation for this review is to summarize the rapidly expanding

Eric Irissou; Jean-Gabriel Legoux; Anatoly N. Ryabinin; Bertrand Jodoin; Christian Moreau

2008-01-01

435

Peregrinations on cold fusion  

SciTech Connect

Attention is focused on the possibility of resonance-enhanced deuteron Coulomb barrier penetration. Because of the many-body nature of the interactions of room-temperature deuterons diffusing through a lattice possessing deuterons in many of the interstitial positions, the diffusing deuterons can resonate on the atomic scale in the potential wells bounded by the ascending walls of adjacent Coulomb barriers and thereby penetrate the Coulomb barriers in a fashion vastly underestimated by two-body calculations in which wells for possible resonance are absent. Indeed, perhaps the lack of robust reproducibility in cold fusion originates from the narrowness of such transmission resonances. 4 refs., 1 fig.

Turner, L.

1989-01-01

436

Hot and Cold  

NSDL National Science Digital Library

In this activity, learners explore temperature changes from chemical reactions by mixing urea with water in one flask and mixing calcium chloride with water in another flask. They observe that the urea flask gets cold and the calcium chloride flask gets hot. The main idea is that some chemical processes release heat energy and are exothermic, while some chemical processes absorb heat energy and are endothermic. This activity is currently used in the Nature of Matter Unit in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

Industry, Oregon M.

1997-01-01

437

Undrained heating and anomalous pore-fluid pressurization of a hardened cement paste  

NASA Astrophysics Data System (ADS)

Temperature increase in a fluid-saturated porous material in undrained condition leads to volume change and pore pressure increase due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the pore volume. This increase of the pore fluid pressure induces a reduction of the effective mean stress, and can lead to shear failure or hydraulic fracturing. This phenomenon is important is important in environmental engineering for radioactive (exothermal) waste disposal in deep clay geological formations as well as in geophysics in the studies of rapid fault slip events when shear heating tends to increase the pore pressure and to decrease the effective compressive stress and the shearing resistance of the fault material (Sulem et al. 2007). This is also important in petroleum engineering where the reservoir rock and the well cement lining undergo sudden temperature changes for example when extracting heavy oils by steam injection methods. This rapid increase of temperature could damage cement sheath integrity of wells and lead to loss of zonal isolation. The values of the thermal pressurization coefficient, defined as the pore pressure increase due to a unit temperature increase in undrained condition, is largely dependent upon the nature of the material, the state of stress, the range of temperature change, the induced damage. The large variability of the thermal pressurization coefficient reported in the literature for different porous materials with values from 0.01MPa/°C to 1.5MPa/°C highlights the necessity of laboratory studies. This phenomenon of thermal pressurization is studied experimentally for a fluid-saturated hardened cement paste in an undrained heating test. Careful analysis of the effect of the dead volume of the drainage system of the triaxial cell has been performed based on a simple correction method proposed by Ghabezloo and Sulem (2008, 2009). The drained and undrained thermal expansion coefficients of the hardened cement paste are also measured in the heating tests. The measured value of the thermal pressurization coefficient is found equal to 0.6MPa/°C and the test results unexpectedly show that it does not change with temperature between 20°C and 55°C. In most geomaterials, as shown experimentally by Ghabezloo and Sulem (2008), the temperature dependency of the thermal expansion of the pore fluid results in temperature dependency of the thermal pressurization coefficient. The observed anomalous thermal pressurization phenomenon is attributed to the anomalous thermal behaviour of cement paste pore fluid. The anomalous thermal behaviour of cement pore fluid is back analysed from the results of the undrained heating test and it is shown that the thermal expansion of the cement paste pore fluid is higher than the one of pure bulk water and is much less sensitive to temperature changes. This anomalous thermal behaviour is due to the confinement of the pore fluid in the very small pores of the microstructure of the cement paste, and also to the presence of dissolved ions in the pore fluid. References: 1.Sulem J., Lazar P., Vardoulakis I. (2007) Thermo-Poro-Mechanical Properties of Clayey Gouge and Application to Rapid Fault Shearing, Int. J. Num. Anal. Meth. Geomechanics, 31(3), 523-540 2.Ghabezloo S., Sulem J. (2008) Stress dependent thermal pressurization of a fluid-saturated rock. Rock Mechanics and Rock Engineering, in press, DOI 10.1007/s00603-008-0165-z. 3.Ghabezloo S., Sulem J., Saint-Marc, J. (2009) The effect of undrained heating on a fluid-saturated hardened cement paste. Cement and Concrete Research, 39(1), 54-64. 4.Ghabezloo S., Sulem J. (2009) Evaluation of the undrained thermo-poro-elastic parameters in a conventional triaxial cell: the effect of the dead volume of the drainage system. Submitted to Int J Rock Mech Min Sci.

Ghabezloo, S.; Sulem, J.; Saint-Marc, J.

2009-04-01

438

Hardening communication ports for survival in electrical overstress environments  

NASA Technical Reports Server (NTRS)

Greater attention is being focused on the protection of data I/O ports since both experience and lab tests have shown that components at these locations are extremely vulnerable to electrical overstress (EOS) in the form of transient voltages. Lightning and electrostatic discharge (ESD) are the major contributors to these failures; however, these losses can be prevented. Hardening against transient voltages at both the board level and system level has a proven record of improving reliability by orders of magnitude. The EOS threats, typical failure modes, and transient voltage mitigation techniques are reviewed. Case histories are also reviewed.

Clark, O. Melville

1991-01-01

439

Atomistic interpretation of solid solution hardening from spectral analysis.  

PubMed

From analysis of a series of vibrational spectra of ir energy absorption and laser Raman, an attempt is made to interpret solid solution hardening from an atomistic point of view for the system CaF(2)/SrF(2). It is shown to be caused by the combined action of three atomic characteristics, i.e., their changes as a function of composition. They are deformation of the atomic coordination polyhedrons, overlap of the outer electron shells of the atom pairs, and the ratio of the ionic to covalent share of binding. A striking nonlinear behavior of the three characteristics, as a function of composition, gives maximum atomic bond strength to the 55/45 position of the system CaF(2)/SrF(2), in agreement with the measured data of the solid solution hardening. The curve for atomic bond strength, derived from the three characteristics, is almost identical to the curve for measured microhardness data. This result suggests that the atomistic interpretation, put forward in this paper, is correct. PMID:20094616

Plendl, J N

1971-05-01

440

A radiation-hardened, computer for satellite applications  

SciTech Connect

This paper describes high reliability radiation hardened computers built by Sandia for application aboard DOE satellite programs requiring 32 bit processing. The computers highlight a radiation hardened (10 kGy(Si)) R3000 executing up to 10 million reduced instruction set instructions (RISC) per second (MIPS), a dual purpose module control bus used for real-time default and power management which allows for extended mission operation on as little as 1.2 watts, and a local area network capable of 480 Mbits/s. The central processing unit (CPU) is the NASA Goddard R3000 nicknamed the ``Mongoose or Mongoose 1``. The Sandia Satellite Computer (SSC) uses Rational`s Ada compiler, debugger, operating system kernel, and enhanced floating point emulation library targeted at the Mongoose. The SSC gives Sandia the capability of processing complex types of spacecraft attitude determination and control algorithms and of modifying programmed control laws via ground command. And in general, SSC offers end users the ability to process data onboard the spacecraft that would normally have been sent to the ground which allows reconsideration of traditional space-grounded partitioning options.

Gaona, J.I. Jr.

1996-08-01

441

DISCREPANT HARDENING OBSERVED IN COSMIC-RAY ELEMENTAL SPECTRA  

SciTech Connect

The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of {approx}70 days, which indicate hardening of the elemental spectra above {approx}200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at {approx}10{sup 15} eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated.

Ahn, H. S.; Ganel, O.; Han, J. H.; Kim, K. C.; Lee, M. H.; Lutz, L.; Malinin, A. [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States); Allison, P.; Beatty, J. J. [Department of Physics, Ohio State University, Columbus, OH 43210 (United States); Bagliesi, M. G.; Bigongiari, G.; Maestro, P.; Marrocchesi, P. S. [Department of Physics, University of Siena and INFN, Siena 53100 (Italy); Childers, J. T.; DuVernois, M. A. [School of Physics and Astronomy, University of Minnesota, MN 55414 (United States); Conklin, N. B.; Coutu, S.; Mognet, S. I. [Department of Physics, Penn State University, University Park, PA 16802 (United States); Jeon, J. A. [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Minnick, S. [Department of Physics, Kent State University Tuscarawas, New Philadelphia, OH 44663 (United States)], E-mail: seo@umd.edu (and others)

2010-05-01

442

Effects of residual stress on irradiation hardening in stainless steels  

NASA Astrophysics Data System (ADS)

Effects of residual stress on irradiation hardening were studied in advance for predicting irradiation assisted stress corrosion cracking. The specimens of SUS316 and SUS316L with several % plastic strains, which correspond to weld residual stress, were prepared by bending and keeping deformation under irradiation. Ion irradiations of 12 MeV Ni 3+ were performed at 330, 400 and 550 oC to 45 dpa. No bended specimen was simultaneously irradiated with the bended specimen. The residual stress was estimated by X-ray residual stress measurements before and after the irradiation. The micro-hardness was measured by using nanoindenter. The residual stress did not relax even for the case of the higher temperature aging at 500 oC for the same time of irradiation. The residual stress after ion irradiation up to high dpa, however, relaxed at these experimental temperatures. The irradiation hardening of stressed specimen was obviously lower than that of un-stressed one in case of SUS316L irradiated at 300 oC to 12 dpa.

Okubo, N.; Miwa, Y.; Kondo, K.; Kaji, Y.

2009-04-01

443

Hardening of new resin cements cured through a ceramic inlay.  

PubMed

This study investigated the degree of hardening achieved through self-curing only and through dual-curing a group of eight new resin-based cements. In addition, the effect of ceramic inlay thickness on cement hardness was determined. Disk specimens measuring 6 mm in diameter and 2.5 mm thick were prepared from eight cements: Adherence, Choice, Duolink, Enforce, Lute-It, Nexus, Resinomer, and Variolink. Eight specimens were prepared from each material; half were self-cured, while the remainder were dual-cured. Knoop hardness measurements were then made at 1-hour, 1-day, and 1-week intervals. In addition 12 specimens of the same dimensions were prepared from each cement and were dual-cured through ceramic spacers of varying thickness (1-6 mm). Hardness measurements were made as above. ANOVA showed significant differences in hardness of self-cured versus dual-cured specimens for all cements (P < 0.0001). Significant differences were also found in the hardness of specimens dual-cured through ceramic spacers 2-3 mm in thickness or more compared with those that were dual-cured without spacer. It is concluded that for some materials self-curing alone was not adequate to achieve sufficient hardening; cement hardness was significantly reduced when ceramic inlay thickness was 2-3 mm or more. PMID:10337297

el-Mowafy, O M; Rubo, M H; el-Badrawy, W A

1999-01-01

444

Heat and cold acclimation in helium-cold hypothermia in the hamster.  

NASA Technical Reports Server (NTRS)

A study was made of the effects of acclimation of hamsters to high (34-35 C) and low (4-5 C) temperatures for periods up to 6 weeks on the induction of hypothermia in hamsters. Hypothermia was achieved by exposing hamsters to a helox mixture of 80% helium and 20% oxygen at 0 C. Hypothermic induction was most rapid (2-3 hr) in heat-acclimated hamsters and slowest (6-12 hr) in cold-acclimated hamsters. The induction period was intermediate (5-8 hr) in room temperature nonacclimated animals (controls). Survival time in hypothermia was relatable to previous temperature acclimations. The hypothesis that thermogenesis in cold-acclimated hamsters would accentuate resistance to induction of hypothermia was substantiated.

Musacchia, X. J.

1972-01-01

445

Cold quark matter  

NASA Astrophysics Data System (ADS)

We perform an O(?s2) perturbative calculation of the equation of state of cold but dense QCD matter with two massless and one massive quark flavor, finding that perturbation theory converges reasonably well for quark chemical potentials above 1 GeV. Using a running coupling constant and strange quark mass, and allowing for further nonperturbative effects, our results point to a narrow range where absolutely stable strange quark matter may exist. Absent stable strange quark matter, our findings suggest that quark matter in (slowly rotating) compact star cores becomes confined to hadrons only slightly above the density of atomic nuclei. Finally, we show that equations of state including quark matter lead to hybrid star masses up to M˜2M?, in agreement with current observations. For strange stars, we find maximal masses of M˜2.75M? and conclude that confirmed observations of compact stars with M>2M? would strongly favor the existence of stable strange quark matter.

Kurkela, Aleksi; Romatschke, Paul; Vuorinen, Aleksi

2010-05-01

446

Cold isopressing method  

DOEpatents

A cold isopressing method in which two or more layers of material are formed within an isopressing mold. One of the layers consists of a tape-cast film. The layers are isopressed within the isopressing mold, thereby to laminate the layers and to compact the tape-cast film. The isopressing mold can be of cylindrical configuration with the layers being coaxial cylindrical layers. The materials used in forming the layers can contain green ceramic materials and the resultant structure can be fired and sintered as necessary and in accordance with known methods to produce a finished composite, ceramic structure. Further, such green ceramic materials can be of the type that are capable of conducting hydrogen or oxygen ions at high temperature with the object of utilizing the finished composite ceramic structure as a ceramic membrane element.

Chen, Jack C. (Getzville, NY); Stawisuck, Valerie M. (North Tonawanda, NY); Prasad, Ravi (East Amherst, NY)

2003-01-01

447

Hot Planet - Cold Comfort  

NSDL National Science Digital Library

This page features videos from the "Hot Planet- Cold Comfort" television episode, related website articles and a student activity. The videos explore how the Gulf Stream conveyor belt may shut down; how Arctic river runoff and Alaskan glacial melt are freshening the oceans; and how ocean sediments and ice cores are being studied to understand the Little Ice Age. The videos total approximately one hour in length. The website articles explore the Little Ice Age; how the Arctic functions as a global thermostat, affecting global weather patterns; and great moments in climate change. The student activity is about light absorbtion. The site also contains a challenge activity to find details in a painting that depict Little Ice Age living conditions.

448

Design of a computer-generated hologram for obtaining a uniform hardened profile by laser transformation hardening with a high-power diode laser  

Microsoft Academic Search

We designed and fabricated a computer-generated hologram (CGH) as a beam shaping optical element for laser transformation hardening with a high-power diode laser (HPDL). Using three-dimensional thermal analysis based on the finite-element method, the intensity distribution of the shaped laser beam was optimized to obtain a uniform hardened depth with 4mm width in a steel plate. Simple experiments of laser

Hideki Hagino; Soichiro Shimizu; Hikaru Ando; Hisao Kikuta

2010-01-01

449

Freezing cold injury.  

PubMed

The pathogenesis of freezing cold injuries (FCI) is not yet entirely understood. Two possible hypothesis emerge: 1) Injury is a direct result of cryogenic insult to the cells. 2) Injury is secondary to vascular stasis which leads to anoxia. In clinical congelatio ice crystallization takes place in the EC-space. When water is transformed into ice, the osmolality in this compartment will increase leading to a passive diffusion of water from the IC-space. Cell dehydration modifies protein structure, alters membrane lipids and cellular pH leading to destructions incompatible with cell survival. Cold induces vasoconstriction of both arterioles and venules, which enhances peripheral filtration and raises plasma viscosity. The stability of red corpuscle aggregates increases and showers of emboli course microvessels. Finally progressive thrombosis will end up in anoxia. The indirect vascular effect has earlier been interpreted similar to that found in non-freezing injuries. Recent studies have, however, shown, that endothelial cells are very sensitive to freezing. The rheologic part of the pathogenesis therefore also seems to depend on a direct injury to cells. The development of FCI does not always depend on ambient temperature and duration of exposure but more to the heat loss subjected to exposed skin. Wind chill, humidity and wetness are all of significance in this matter. From a clinical point of view FCI are best subdivided into superficial and deep injuries. The superficial frostbite is limited to the skin and nearest subcutaneous tissue. A stringing, pinching pain is often the first symptom. The affected area becomes pale or waxy-white and numb.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1811585

Granberg, P O

1991-01-01

450

Effect of oxide layer growth on diode laser beam transformation hardening of steels  

Microsoft Academic Search

The surfaces of low alloy and martensitic stainless steels have been transformation hardened in inert and oxidizing atmospheres using a high-power diode laser beam. The effect of oxide layer growth on the absorptivity of the materials to the laser beam is investigated. When hardening was performed in an inert atmosphere, absorptivity values between 35% and 40% were obtained for both

Henrikki Pantsar; Veli Kujanpää

2006-01-01

451

Thermal analysis of laser surface transformation hardening—optimization of process parameters  

Microsoft Academic Search

This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P; laser beam diameter, Db; and the heat intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears

R. Komanduri; Z. B. Hou

2004-01-01

452

Mathematical modeling of localized melting around graphite nodules during laser surface hardening of austempered ductile iron  

Microsoft Academic Search

An attempt has been made to mathematically predict the optimum conditions of laser surface hardening (LSH) of austempered ductile iron (ADI) that can ensure a predominantly martensitic microstructure and preclude partial\\/complete dissolution of graphite nodules in the laser hardened zone during laser irradiation. The exercise involves prediction of the thermal profile (using the Ashby and Easterling model), and consequently, the

A. Roy; I. Manna

2000-01-01

453

SENSITIVITY ANALYSIS OF PROCESSING PARAMETERS BY DIRECT DIFFERENTIATION METHOD FOR LASER SURFACE HARDENING TREATMENT  

Microsoft Academic Search

The present study deals with an application of the finite element method to the sensitivity analysis of processing parameters for laser surface hardening treatment. Computing the sensitivity of temperature distributions to changes in processing parameters allows one to determine the more effective input parameters for laser surface hardening treatment. The interesting processing parameters are taken as the characteristic beam radius

S.-H. Lee; Y.-S. Yang

2001-01-01

454

Prediction of hypo eutectoid steel softening due to tempering phenomena in laser surface hardening  

Microsoft Academic Search

The paper presents a mathematical model for predicting material mechanical property variation, in laser hardening of hypo eutectoid steel, when the softening effects due to the overlapping trajectories are considered. This generally occurs during laser hardening of industrial parts, especially when wide areas have to be treated, due to the tempering phenomena.An original tempering model for the prediction of the

G. Tani; L. Orazi; A. Fortunato

2008-01-01

455

Laser-assisted machining of hardened steel parts with surface integrity analysis  

Microsoft Academic Search

Machining of hardened steel components has traditionally been the domain of grinding. A laser-assisted machining (LAM) process with a larger material removal rate is developed to replace the currently used hard turning and grinding operations for machining hardened steel shafts. A three-dimensional transient thermal model is developed to predict the temperature field in the hollow shaft of varying thickness undergoing

Hongtao Ding; Yung C. Shin

2010-01-01

456

2 kW cw Nd:YAG laser surface hardening  

Microsoft Academic Search

Some classical surface hardening methods require a new machining after treatment or a break in line machining. The laser surface hardening allows the user to avoid these disadvantages. Moreover the associated Nd:YAG laser optical fiber enables the user to become independent of the piece geometry: in our case, an extrusion screw. In order to control the depth quenched by Nd:YAG

G. Duffet; P. Kirat; H. Andrzejewski; A. B. Vannes

1997-01-01

457

Reliable and efficient equilibrated a posteriori finite element error control in elastoplasticity and elastoviscoplasticity with hardening  

Microsoft Academic Search

This paper establishes the reliability and efficiency of equilibrated a posteriori estimates for L2 stress error control of conforming displacement finite element approximations of incremental plasticity and viscoplasticity with hardening. Explicit expressions for upper bounds of the reliability constant that enters the guaranteed upper error bound illustrate its crucial dependence on the hardening material constants. Numerical experiments show that adaptive

C. Carstensen; R. Klose; A. Orlando

2006-01-01

458

Calculated hardenability for improved consistency of properties in heat treatable engineering steels  

NASA Astrophysics Data System (ADS)

Hardenability is one of the most important parameters controlling the heat treated properties of engineering steels. It affects the consistency of response for microstructure, hardness, strength, toughness, and dimensional change (distortion). This study illustrates that a major benefit of controlling hardenability is improving the consistency of dimensional distortion resulting from heat treatment. To facilitate the supply of steels to hardenability limits, especially restricted hardenability, a new technique was developed for the prediction of Jominy hardenability from chemical composition. The technique, termed the “Database Method,” uses measured Jominy hardenability and chemical composition data, contained in a database, to calculate the hardenability for a query composition. Using up to ten known steels, selected from the database with compositions closely matching that of the query steel, a small adjustment is made to the measured hardenability of each known steel allowing for the small difference in composition between the query and chosen steel. The final calculated result for the query steel is taken as the average of the various estimates. The basis of the Database Method is explained, and the advantages are illustrated for selecting engineering grades.

Cook, W. T.; Morris, P. F.; Woollard, L.

1997-08-01

459

Work hardening and mechanical equation of state in some metals in monotonic loading  

Microsoft Academic Search

The work hardening coefficients of Type 316 stainless steel niobium, and 1100 aluminum alloy are measured in tensile tests. It is demonstrated experimentally that in the measured stress, plastic strain rate, and temperature range the work hardening coefficient depends only on the stress and plastic strain rate. The significance of the experimental results is discussed in terms of the concept

G. L. Wire; F. V. Ellis; C. Y. Li

1976-01-01

460

Work hardening and mechanical equation of state in some metals in monotonic loading  

Microsoft Academic Search

The work hardening coefficients of Type 316 stainless steel, niobium, and 1100 aluminum alloy are measured in tensile tests. It is demonstrated experimentally that in the measured stress, plastic strain rate, and temperature range the work hardening coefficient depends only on stress and plastic strain rate. The significance of the experimental results is discussed in terms of the concept of

G. L. Wire; F. V. Ellis; C. Y. Li

2011-01-01

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