Age of onset of child maltreatment predicts long-term mental health outcomes.

The authors tested the hypothesis that children who are maltreated earlier in life are at greater risk for poor psychological functioning in adulthood than those maltreated later in life. Age of onset of maltreatment was assessed with 3 classifications: (a) continuous (ages 0-11 years); (b) dichotomous (early [ages 0-5 years] vs. later [ages 6-11 years]); and (c) developmental (infancy [ages 0-2 years], preschool [ages 3-5 years], early school age [ages 6-8 years], and school age [ages 9-11 years]). Individuals with documented cases of physical and sexual abuse and neglect prior to age 12 (N=496) were followed up and assessed in adulthood. Results indicated that an earlier onset of maltreatment, measured dichotomously and developmentally, predicted more symptoms of anxiety and depression in adulthood, while controlling for gender, race, current age, and other abuse reports. Later onset of maltreatment, measured continuously or developmentally, was predictive of more behavioral problems in adulthood. Implications for the assessment of maltreated children, the prevention of adult psychopathology, and the classification of age of maltreatment onset are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interstitial atom configurations in stable and metastable Fe-N and Fe-C solid solutions

Mössbauer Fe⁵⁷ spectroscopy allows comparison of Fe?N and Fe?C interstitial solid solutions. The spectra of Fe?N retained austenite indicate that nitrogen atoms are randomly distributed on octahedral sites in the austenite and in the virgin martensite. On heating, austenite decomposes directly to the equilibrium phases α iron and Fe₄N at temperatures above 160°C. Virgin martensite ages at room temperature by local ordering of nitrogen atoms. In that process, three new iron atom environments develop, characteristic of the Fe₁₆N₂ (α″) structure. However, the excessive width of the peaks indicate the perfect order of the Fe₁₆N₂ precipitate is not achieved, except after very long times. Further aging at 100°C leads to the complete decomposition of the virgin martensite to the discrete phases α iron and Fe₁₆N₂. This two phase structure is stable up to 160°C, above which the precipitation of Fe₄N occurs. These results are in contrast to Fe?C data. Carbon atoms in retained austenite tend to be far apart in their octahedral sites, and this nonrandom distribution is inherited by the virgin martensite. Fe?C austenite decomposes by the formation of ∈ carbide below 160°C and precipitation of Fe₃C above 180°C. The carbon atoms in virgin martensite agglomerate at room temperature and regions of ordered Fe₄C are believed to result. Subsequently ∈ carbon is formed at 80°C and Fe₃C precipitates above 160°C.¹     

Phase transitions and shape memory in NiTi

The “premartensitic” transformation of the B2 phase in NiTi was studied using electrical resistance measurement, X-ray diffraction, and shape-change effects. The degree of rhombohedral distortion of that transformation and the electrical resistance change show similar temperature dependence. In particular, whenT _R » M_s, this encompasses a narrow temperature region of rapid increase just belowT _R, followed by an extended range of levelling off. The onset of the martensitic transformation is not necessarily preceeded by the rhombohedral distortion, and the latter proceeds continuously belowT _R and persists throughout the martensite transformation range. Thus three kinds of phase transformation can occur: B2 ai R, B2 ai M, R ai M; B2 ai R is not a precursory phenomenon. Observations on the two-way memory (TWM) and its correlation to resistance changes in NiTi leads to the conclusion that whenT _R >M _s, the TWM is comprised of two stages. On cooling, the B2 → R transformation is responsible for the initial stage, which is thermally reversible without hysteresis. The second stage of the TWM, which is due to martensite formation, is reversible in shape change, but with a thermal hysteresis. It is also suggested that on heating, the R → B2 transformation can contribute to the primary shape memory effect in NiTi.     

Mössbauer effect studies of tempered martensite

The⁵⁷Fe Mössbauer effect has been widely used to trace the tempering of Fe-C and Fe-N martensitic systems, and has provided much detailed information on the interstitial atom configurations formed during these processes. Carbon and nitrogen atoms are found predominantly to o°Cupy octahedral interstitial positions in the virgin martensite structure. During aging at room temperature, the interstitial atoms tend to agglomerate to regions of high carbon or nitrogen content. Carbon atoms are believed to cluster by jumping from tetrahedral interstitial sites and/or forming regions of ordered Fe₄C. Nitrogen atoms agglomerate to regions of ordered Fe₁₆N₂. On tempering above room temperature, the sequential precipitation of the ε or η, ? and θ carbides is observed in Fe-C systems. The α (Fe₁₆N₂) and γ′ (Fe₄N) nitrides are observed during the decomposition of Fe-N martensite. Mössbauer hyperfine spectra associated with each of these structures are described.     

When similarity is a liability: Effects of sex-based preferential selection on reactions to like-sex and different-sex others.

In 2 laboratory studies, 145 male and female undergraduates were selected for the role of manager either on the basis of merit or preferentially on the basis of their sex. Results of the 1st study indicate that when female Ss had been selected preferentially as compared with on a merit basis, they reacted more negatively to female (but not to male) applicants for an entry-level position in terms of personnel evaluations and competence ratings and they recommended female applicants for hire less frequently and less enthusiastically. No differences in personnel evaluations were found as a result of preferential selection when the Ss were male (Study 1) or when Ss were provided with favorable information about their ability (Study 2). Implications for implementation of affirmative action programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mössbauer spectroscopy of hexagonal iron-nitrogen alloys

In Fe?N alloys, the hexagonal-close-packed phase can be completely retained metastably at room temperature by rapid quenching from 700°C, with nitrogen contents ranging from about 17 to 27 at. pct N; (between the latter composition and 33 at. pct N, the hexagonal phase is stable at room temperature). The phase is ferromagnetic; the Curie temperature is a sharp function of nitrogen content, with the maximum Curie point (about 300°C) occurring at 24 at. pct N. The Curie point is below room temperature in the hexagonal phase for nitrogen contents less than about 17.5 at. pct N. For alloys of the Fe₃N composition quenched from various temperatures, Mössbauer spectroscopy indicates that the hexagonal phase undergeos ordering of nitrogen atoms on interstitial sites.     

The kinetics of carbon clustering in martensite

Metallurgical and Materials Transactions A - The rate of clustering of carbon atoms into regions of ordered Fe4C has been studied by Mössbauer spectroscopy. The activation energy associated...     

Mössbauer Effect Studies of Tempered Martensite

The⁵⁷Fe Mössbauer effect has been widely used to trace the tempering of Fe-C and Fe-N martensitic systems, and has provided much detailed information on the interstitial atom configurations formed during these processes. Carbon and nitrogen atoms are found predominantly to occupy octahedral interstitial positions in the virgin martensite structure. During aging at room temperature, the interstitial atoms tend to agglomerate to regions of high carbon or nitrogen content. Carbon atoms are believed to cluster by jumping from tetrahedral interstitial sites and/or forming regions of ordered Fe₄C. Nitrogen atoms agglomerate to regions of ordered Fe₁₆N₂. On tempering above room temperature, the sequential precipitation of the ε or η, χ and θ carbides is observed in Fe-C systems. The α′’ (Fe₁₆N₂) and γ′ (Fe₄N) nitrides are observed during the decomposition of Fe-N martensite. Mössbauer hyperfine spectra associated with each of these structures are described.     

The distinctness of magnetic hyperfine fields associated with structurally unique iron sites in Fe3B

Mössbauer spectra were measured of Fe₃B, which is isostructural to orthorhombic Fe₃C. The metastable Fe₃B compound was formed by splat cooling Fe-1.5 wt pct B alloys. Two hyperfine spectra are found, corresponding to effective fields of 235 KOe for one type of iron atom and 264 KOe for the other. Isomer shifts were positive with respect to α-iron, also present in the sample.