Influence of cryomilling on the microstructural features in HVOF-sprayed NiCrAlY bond coats for thermal barrier coatings: Creation of a homogeneous distribution of nanoscale dispersoids

Previous research has revealed that thermal barrier coatings with cryomilled bond coats exhibit improved thermal cycling lifetime by growing a continuous and uniform oxide layer at a slower rate; yet the mechanism controlling the ultimate failure remains unclear. In an effort to provide a foundation for understanding the improved behavior, the influence of cryomilling on the microstructure of the NiCrAlY bond coat material is investigated in this article. Rather than focusing on the alumina scale formation, the microstructural features and their evolution within the high-velocity oxy-fuel (HVOF)-sprayed NiCrAlY bond coats themselves, prepared from conventional powder and cryomilled powder, were carefully compared through extensive scanning electron microscope/energy-dispersive X-ray spectroscopy characterization. In addition, the as-cryomilled NiCrAlY powder is characterized to provide evidence of the direct influence of cryomilling and to exclude the impact from the HVOF spraying. It is found that the essential change in microstructural features resulting from the cryomilling is the creation of a homogeneous distribution of ultrafine (nanoscale) Al-rich oxide/nitride dispersoids, which remain thermally stable even after exposure at 1100°C for 100 h. The TEM study on the as-cryomilled powder, prior to the HVOF spraying, indicates that some Al and Y-rich oxides are already present within the material as a direct result of the cryomilling process.     

Dynamic balance between grain refinement and grain growth during high-pressure torsion of Cu powders

High-pressure torsion (HPT) was applied to unmilled coarse-grained (CG) Cu powders with low initial dislocation density and cryomilled nanocrystalline (nc) Cu powders with high initial dislocation density, with identical processing parameters. HPT of unmilled CG Cu powders resulted in exceptional grain refinement and increase in dislocation density, whereas significant grain growth and decrease in dislocation density occurred during HPT of cryomilled nc Cu powders. Equilibrium structures were achieved under both conditions, with very similar stable grain sizes and dislocation densities, suggesting dynamic balances between deformation-induced grain refinement and grain growth, and between deformation-induced dislocation accumulation and dislocation annihilation. The equilibrium structures are governed by these two dynamic balances.     

Formation of profuse <c+a> dislocations in deformed calcium-containing magnesium alloys

We report that <c+a> pyramidal slipping could be more easily activated in textured Mg–Ca alloys with increasing Ca contents dissolved in α-Mg matrix under tensile deformation, and it is proposed that the decreased stacking fault energy plays the critical rule. In contrast, only twins and <a> basal dislocations are observed in the compressed samples. The results would provide insight into understanding of the deformation mechanism and designing more ductile Mg alloys.     

Production of recrystallized nano-grains in a fine-grained Cu–Zn alloy

A fine-grained Cu–30%Zn alloy sheet was rolled at 77 K to induce ultrafine mechanical twins. Subsequent annealing of the rolled alloy at temperatures up to 543 K led to the uniform appearance of recrystallized ultrafine grains (UFGs), which contained numerous annealing twins. Average grain sizes of 150 ～ 300 nm were produced in this way. The formation of such UFGs during annealing is attributed to the high nucleus density associated with the fine initial grain size as well as to the high densities of mechanical twins and dislocations produced by cryorolling. The high driving force for recrystallization enabled the use of relatively low annealing temperatures, which limited the subsequent grain growth.     

Age differences in genetic and environmental influences on eating attitudes and behaviors in preadolescent and adolescent female twins

A sample of 680 11- and 602 17-year-old female twins was used to examine (a) age differences in genetic and environmental influences on disordered eating attitudes and behaviors and (b) associations between body mass index (BMI) and eating attitudes and behaviors. Univariate, biometrical model-fitting analyses indicated that 11-year-old twins exhibited less genetic and greater shared environmental influence on eating attitudes and behaviors than 17-year-old twins. Bivariate model-fitting analyses indicated that the relationship between BMI and eating attitudes was mediated primarily by common shared environmental influences in 11-year-old twins and common genetic influences in 17-year-old twins. Nonetheless, the majority of genetic influences on eating attitudes and behaviors in older twins were due to genetic effects that are independent of those operating in BMI.     

Ductile fracture mechanism in fine-grained magnesium alloy

The ductile fracture mechanism in a fine-grained magnesium alloy has been investigated by transmission electron microscopy-focused ion beam techniques. In coarse-grained or conventional magnesium alloys, twins form at the very beginning of the deformation process, and crack propagation occurs through the twin boundaries. However, in the alloy used in this study, subgrain structures were found instead of twins at the crack tip. Nanoscale twins formed subsequently owing to large stress in the crack propagation route. The fine-grained alloys showed high fracture toughness resulting from resistance to the twins at the beginning of the deformation.     

The effect of classroom environment on problem behaviors: A twin study

Children's behavior problems, both internalizing and externalizing, are a function of both genetic and environmental influences. One potentially important environmental influence is the classroom environment. This study of 1941 monozygotic twin pairs examined whether children whose parents rated them as similarly high or low on a number of problem behaviors were rated in the same way by teachers when they were together versus separated in their classrooms at school. Results showed that twins in the same classrooms were rated by their teachers more similarly on each dimension of problem behavior than were twins who were separated into different classrooms, suggesting that the classroom environment is important in predicting differences between twins in terms of problem behaviors at school. In addition, parents' ratings of problem behaviors were lower for twins placed in the same classroom versus twins in different classrooms. Thus, there is reason to consider whether, at least during the early school years, parents should be allowed to make the decision to not separate twins at school.     

Suicide attempts in twins whose co-twins' deaths were non-suicides

Familial similarity for suicidal behavior has been interpreted by psychosocially oriented researchers as reflecting extreme grief following loss. This view would anticipate a higher frequency of attempted suicide among bereaved MZ than DZ twins (regardless of cause of death), given their generally increased social closeness. Alternatively, support for a genetic influence on suicidal behavior has been provided by findings of greater concordance among monozygotic (MZ) than dizygotic (DZ) twins, and among biological than adoptive relatives. This approach predicts that the occurrence of suicidal attempts among bereaved MZ and DZ twins whose co-twins deaths were non-suicides should not differ and should be low in frequency, given an absence of predisposing genetic factors. Attempted suicide was compared in 166 MZ and 79 DZ twins whose co-twins' deaths were non-suicides. Suicidal attempts (during the first two months following the loss) were recalled by 3 MZ twins (1.8%) and by 3 DZ twins (3.7%), a difference that was not significant. The present study, together with previous twin and adoption studies, supports the view that concordance for suicide among family members reflects a common genetic predisposition to suicidal behavior.     

瑞典的双生子与子代研究： 通过双生子及其家庭来增加对遗传与环境互动的了解

双生子及子代研究（TOSS）收集了909对双生子及他（她）们的配偶和他（她）们的青少年子女的数据。设计该项目是为研究以下三个问题：1）遗传与环境是如何影响双生子父母的养育方式的？2）遗传与环境是如何影响成年人的家庭关系的？3）家庭关系是如何影响成年人的心理调适的？由于此研究包括了双生子及其子女,该设计可以与其他研究相比较来具体地分析遗传与环境的关联。此研究的结果有助于厘清遗传与环境在养育方式和家庭关系中的型态,同时也澄清了父母亲个人特征是如何影响他（她）们的养育方式,以及父母的个体特征是如何帮助解释了遗传对家庭关系的影响。此研究今后将进一步分析遗传与环境的关联与互动,以及候选基因与环境的关联与互动     

SOME PERSONALITY TESTS APPLIED ON IDENTICAL TWINS

(1) The study concerns Rorschach, Children Apperception Test, Bender Gestalt Test and Draw-a-Man. Data have been obtained on a number of personality variables from 12 pairs of identical twins at the ages of 9;6–10;6. (2) For the Ro 17 out of 21 and for the CAT 15 out of 23 intraclass coefficients are positive. The coefficients for the Gestalt test and Draw-a-Man are high and positive. It is argued that intraclass coefficients must be considered as underestimating both the true reliability of the ratings and the correlation between true scores for identical twins. (3) The intertest correlations give support to the construct validity of the ratings on the variables studied. Especially favourable are the intercorrelations for 'General adjustment'.     

Children''s Behavioral Inhibition Over Age and Across Situations: Genetic Similarity for α Trait During Change

Ratings of behaviors pertaining to inhibition were observed for 130 twins participating in a longitudinal study. Ratings were available for four ages (12, 18, 24, and 30 months) and from three sources at each age: direct observations obtained in a laboratory setting, direct observations obtained in conjunction with infant mental testing, and a temperament measure from a questionnaire completed by parents. For the individual twins, the age-to-age correlations were in the moderate range (.26 to .64). The situation-to-situation correlations were generally in the same range (.17 to .64). When the twins were recombined into twin pairs, within-pair (intraclass) correlations indicated that monozygotic (MZ) twins were more concordant than dizygotic (DZ) twins for each of the behaviors at each of the ages. Also, the MZ twins were more concordant for the direction and degree of behavioral change from age to age or from situation to situation. These data provide additional evidence for the biological influence on behavioral inhibition, a characteristic that has been studied in temperament and personality research. The results suggest that the trait of behavioral inhibition and a change in the trait are genetically conditioned. In addition, it is suggested that the concept of trait be expanded to include the person-centered biological regulation of change.     

Separation—Individuation,Self-Concept,and Object Relations in Fraternal Twins,Identical Twins,and Singletons

Identical twins, fraternal twins, and singletons (n = 30 in each group) were compared on objective measures of separation–individuation, object relations, and self-esteem. No significant differences were found. The data did not support the popular notion that twins face special problems with respect to personality development or the idea that twins have more difficulty than others in establishing and maintaining close relationships. Twins and nontwins did not differ significantly with respect to marital status, number of years married, whether married before, number of previous marriages, number of years divorced, or living arrangements if single. The majority of twins had been raised in a way that encouraged at least some individual differences.     

Sources of covariation among attention-deficit/hyperactivity disorder, oppositional defiant disorder, and conduct disorder: the importance of shared environment.

Research has documented high levels of covariation among childhood externalizing disorders, but the etiology of this covariation is unclear. To unravel the sources of covariation among attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and conduct disorder (CD), the authors studied 11-year-old twins (N = 1,506) from the Minnesota Twin Family Study. Symptom counts for each of these disorders were obtained from interviews administered to the twins and their mothers. A model was fit that allowed the parsing of genetic, shared environmental (factors that make family members similar to each other), and nonshared environmental (factors that make family members different from each other) contributions to covariation. The results revealed that although each disorder was influenced by genetic and environmental factors, a single shared environmental factor made the largest contribution to the covariation among ADHD, ODD, and CD.     

Genetic mediation of the relationship between social support and psychological well-being.

This study assessed genetic and environmental influences on the association between social support and psychological functioning using the combined adoption/twin design from the Swedish Adoption/Twin Study of Aging. A subsample of 424 twin pairs, 50 years and older, was used: 64 pairs of identical twins reared apart, 95 pairs of identical twins reared together, 132 pairs of fraternal twins reared apart, and 133 pairs of fraternal twins reared together. Multivariate model-fitting analyses indicated that the relationship between the perceived adequacy of social support and psychological well-being (depression and life satisfaction) was mediated in part by genetic factors.     

Born in Korea-adopted apart: Behavioral development of monozygotic twins raised in the United States and France

Monozygotic (MZ) twins raised in different countries and cultures are rare. This report examines behavioral and physical similarities and differences of MZ female twins from South Korea, but raised separately in the United States and France. Analyses of the twins’ intelligence, special cognitive abilities, personality traits, self-esteem, job satisfaction and health histories are considered with reference to their genetic relatedness and rearing conditions. Both striking similarities and intriguing differences were noted.     

Cross-sequential analysis of genetic influences on cognitive ability in the swedish adoption/twin study of aging

Abstract

Cross-sequential methods of analysis were applied to cognitive data from the Swedish Adoption/Twin Study of Aging. Thirteen measures of cognitive ability assessing four major domains (verbal, spatial, memory, and perceptual speed) were collected at two times of measurement separated by a three-year interval. Data were available from 41 pairs of monozygotic twins reared apart (MZA), 54 pairs of monozygotic twins reared together (MZT), 86 pairs of dizygotic twins reared apart (DZA), and 73 pairs of dizygotic twins reared together (DZT) ranging in age from 41 to 84 years. Cross-sectional differences and longitudinal changes in total variance and sources of variance were examined. With a few exceptions, both cross-sectional and longitudinal stability were found for total variance. In addition, few cross-sectional differences and longitudinal changes were found for genetic and environmental components of variance.     

Mate choice and friendship in twins: evidence for genetic similarity

This study examined the genetic and environmental contribution to people's preference for spouses and friends to be similar to themselves. In their responses to 130 personality, attitude, and demographic questions, 174 pairs of monozygotic (MZ) twins resembled each other (r= .53) more than did 148 pairs of dizygotic (DZ) twins (r= .32), 322 pairs of spouses (r= .32), and 563 pairs of best friends (r= .20). It was not previously recognized that spouses and friends are as similar as DZ twins. MZ twins also chose spouses and best friends more similar to their co-twins' friends and spouses than did DZ twins (mean rs = .22 vs. .14). The twins' preference for spouses and friends similar to themselves was about 34% due to the twins' genes, 12% due to the twins' common environment, and 54% due to the twins' unique (nonshared) environment. Similarity to partners was more pronounced on the more heritable items than the less heritable items. It is concluded that people are genetically inclined to choose as social partners those who resemble themselves at a genetic level.     

“Principles in his nature which interest him in the fortune of others…”: The heritability of empathic concern for others1

The present research was conducted to explore genetic influences on empathic concern for others. First, an index of empathic concern was created by combining relevant items from Gough's Adjective Check List (ACL). This index was validated by correlating scores of 88 undergraduates on the index with their scores on a self-report measure of empathy, which has been related to prosocial behavior. Correlations were sufficiently high to accept the validity of the index. Next, previously collected ACL responses of 114 monozygotic (MZ) and 116 dizygotic (DZ) twins were reanalyzed in order to create an empathic concern score for each twin. The twins were middle-aged males initially raised together but living apart at the time they completed the ACL. Comparison of intraclass correlations for MZ and DZ twins revealed, as predicted by the genetic hypothesis, significant (p < .005) heritability in empathic concern scores. This finding suggests that there may, indeed, be a genetic influence on individual differences in empathic concern for others. Some limitations of the present data are also considered. How selfish soever man may be supposed, there are evidently some principles in his nature which interest him in the fortune of others, and render their happiness necessary to him.     

Genetic and Rearing Environmental Influences on Adult Personality: An Analysis of Adopted Twins Reared Apart

ABSTRACT We report a genetic and environmental analysis of California Psychological Inventory (CPI) scale scores gathered on a sample of 45 sets of monozygotic twins reared apart (MZA) and 26 sets of dizygotic twins reared apart (DZA) Analysis of twin intraclass correlations and the results of models fit to the twin data demonstrate that the heritability of most scales and five factors of the CPI is about 50 When compared to results from studies of adult MZ and DZ twins reared together few of the scales demonstrate any common family environmental influence Placement coefficients on the Family Environment Scale (FES) can explain only a minor portion of the correlations for twins reared apart The influence of specific rearing environmental factors on adult personality was evaluated by analyzing the relationship between the FES and the CPI in this adoptee sample One FES factor (Cohesion vs Conflict) does correlate substantially with the CPI factor of Consensuality and may account for up to 24% of the variance in that factor, but the retrospectively gathered     

A twin study of computer anxiety in Turkish adolescents

The present study investigated computer anxiety within a sample of Turkish twins aged 10-18. A total of 185 twin-pairs participated in the study. Of the twins, 64 pairs (34.6 percent) were monozygotic (MZ) and 121 pairs (65.4 percent) were dizygotic (DZ). Of the 121 DZ twins, 54 pairs (44.63 percent) were same-sex twins and 67 pairs (55.37 percent) were opposite-sex twins. Computer anxiety was assessed using Computer Anxiety Rating Scale-Turkish Version (CARS-TV), one of the three main scales of "Measuring Technophobia Instruments" developed by Rosen and Weil. The results of paired t test comparisons showed no significant differences in MZ and same-sex DZ twin-pairs' levels of computer anxiety. On the other hand, a significant difference was found in opposite-sex DZ twin-pairs' level of computer anxiety. Interesting enough, males appeared to be more computer anxious than their female co-twins. In the present study, using Falconer's formula, heritability estimate for computer anxiety was derived from correlations based on MZ and DZ twins' mean scores on CARS-TV. The results showed that 57 percent of the variance in computer anxiety was from genetics and 41.5 percent was from nonshared environmental factors. Shared environmental influence, on the other hand, was very small and negligible. Interpretations of results and potential directions for future research are presented.