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Background/aimsTo evaluate whether anterior segment anatomy and axial length are associated with prematurity and perinatal factors in adults.MethodsThe Gutenberg Prematurity Eye Study examined adults born preterm and term aged 18–52 years. All participants underwent a prospective ophthalmic examination (optical biometry via a LenStar 900, Haag-Streit) in Germany. The associations between gestational age (GA), birth weight (BW) and BW percentile, retinopathy of prematurity (ROP) occurrence, ROP treatment and other perinatal factors with the main outcome measures were evaluated by univariate and multivariable linear regression analyses. Main outcome measures were corneal radius, white-to-white distance, anterior chamber depth, lens thickness and axial length.ResultsThe study involved 861 eyes of 438 preterm and full-term individuals (aged 28.6±8.7 years, 245 females,). After adjustment for age and gender, a steeper corneal radius was associated with lower GA (B=0.02; p<0.001) and a lower BW percentile (B=0.003; p<0.001). A smaller white-to-white distance was linked to lower GA (B=0.02; p<0.001), a lower BW percentile (B=0.004; p<0.001) and postnatal ROP occurrence (B=−0.26; p<0.001). Decreased axial length was associated with lower GA at birth (B=0.05; p=0.002) and pre-eclampsia (B=−0.34; p=0.015). ROP-treated eyes had a shallower anterior chamber depth (B=−0.63; p=0.001) and increased lens thickness (B=0.64, p<0.001).ConclusionOur analyses in adults demonstrate that the corneal morphology is influenced by GA and BW percentile, while the anterior chamber depth and lens thickness are affected by ROP treatment, namely laser therapy and cryotherapy. The present study highlights that perinatal factors lead to lifelong sequelae of ocular shape.

Yttria-stabilized zirconia (YSZ) has become an indispensable solid electrolyte material in modern solid oxide fuel and electrolysis cells (SOFCs/SOECs) as well as oxygen sensors. The oxygen ionic conductivity of YSZ is among the highest known so far. For energy efficiency optimization of SOFCs and lowering the high-temperature degradation of electrodes, the oxygen ionic conductivity needs to be further enhanced. This would allow for a reduction in application temperature. Despite extensive regular point defect-doping strategies, this key issue remains unsolved. Here, we investigate the role of mechanically induced dislocations (line-defects) on electrical conductivity and oxygen transport in bulk YSZ. An advanced mechanical deformation approach is employed to generate distinctly aligned dislocation-rich and -deficient regions. The in-depth electrical characterization of these regions exhibited highly conducting effects of dislocation-induced strain inside the bulk material. Furthermore, targeted oxygen tracer diffusion experiments prove enriched oxygen incorporation within the dislocation bundles. Therefore, the potential of mechanically induced dislocations is elucidated as a design element to tune the bulk ionic transport in YSZ.

Understanding the surface defect chemistry and its strain dependency is essential in developing next-generation electrochemical devices. However, due to their nanoscale dimensions, surface defects cannot be accessed by conventional techniques used in bulk defect studies. Here, we constructed the strain-dependent surface defect equilibria (i.e., the Brouwer diagram) of mixed ionic-electronic conducting perovskite oxides with near ambient pressure X-ray absorption spectroscopy. Using coherently strained thin-film La0.6Sr0.4FeO3(LSF) as model systems, we probed their surface defect equilibria at 400 °C in oxygen partial pressures between 1 and 10–5Torr. We found that the electron holes on the LSF surfaces have strong oxygen character, regardless of the strain states. Nevertheless, tensile strain makes the LSF surface more reducible than the compressed counterpart. These two observations were then validated using first-principles calculations. Finally, with the aid of thermodynamic analyses, we showed that the strain-dependent surface defect equilibria of LSF can be captured by bulk-like ideal solution defect models with shifted oxygen chemical potentials. The findings and methodology presented in this study enable quantitative determination of the surface defect chemistry, which is crucial to understanding and designing functional surfaces for efficient conversions of energy and fuels.

This article explores how employment affects the likelihood of dropout among high school students in Baltimore, a high-poverty city with a high dropout rate. Among 15-year-olds, those with teen jobs (e.g., lawn mowing, babysitting, etc.) were less than one third as likely to drop out as those who took adult-type jobs (manufacturing or business). This pattern reversed at age 16, however, because, at that age, holding an adult-type job as compared to a teen job reduced dropout risk. Patterns of work, for those older than ages 15 and 16, also affected dropout risk. Students who had been retained, but who made an orderly transition into work, were less likely to drop out than retained students who made a disorderly transition. Keywords: teenage work; effects of retention; dropout hazard

PurposeLow birth weight (BW) is linked to impaired organ development in childhood, including altered ocular morphological and functional development. The aim of this study was to evaluate whether low BW has long-term effects on visual acuity and refraction in adulthood.MethodsThe Gutenberg Health Study is a population-based, observational cohort study in Germany, including 15 010 participants aged between 35 and 74 years. These participants were divided into three different BW groups (low: <2500 g; normal: between 2500 and 4000 g; and high: >4000 g). Best-corrected visual acuity and objective refraction were examined. We used multivariable linear regression models with adjustment for age, sex, socioeconomic status and self-reported glaucoma, age-related macular degeneration, corneal disease and cataract to assess associations between BW and the main outcome measures, best-corrected visual acuity, spherical equivalent and astigmatism.ResultsOverall, 8369 participants reported their BW. In a multivariable analysis, an association for low BW with spherical equivalent (B=−0.28 per dioptre, P=0.005) and best-corrected visual acuity (B=0.02 logarithm of the minimum angle of resolution, P=0.006) compared with normal BW was observed. For participants with high BW, an association was observed with spherical equivalent (B=0.29 per dioptre, P<0.001), while none with visual acuity.ConclusionsOur data demonstrated that low BW is linked to visual acuity and refractive long-term outcomes long after childhood. Individuals with low BW are more likely to have lower visual acuity and a higher myopic refractive error in adulthood. Adults with high BW are more likely to have a more hyperopic refractive error.

While the educational difficulties of poor black students are well documented and have been discussed extensively, the academic performance of well-off African American children has received much less attention. Even with economic and educational resources in the home, well-off African American youth are not achieving at the levels of their white peers. Why is this? A review of relevant literature identifies a set of social processes that pose formidable barriers to the academic and personal development of middle-class African American youth, the closing of the black-white achievement gap, and the preservation of African American family advantage across generations. Constituting a social ecology of African American family life, these processes emanate outward from the immediate home environment, through peers and friends, into neighborhoods and schools, and to society at large.

From a life course perspective, high school dropout culminates a long-term process of disengagement from school. The present paper uses data from a representative panel of Baltimore school children to describe this unfolding process. Over 40% of the study group left school at some point without a degree, but this high overall rate of dropout masks large differences across sociodemographic lines as well as differences involving academic, parental, and personal resources. A sociodemographic profile of dropout for the study group shows how dropout rates vary across different configurations of background risk factors including family socioeconomic status (SES), family type, and family stress level. Dropout risk factors and resources in support of children's schooling then are examined at four schooling benchmarks: the 1st grade, the rest of elementary school (years 2–5), the middle school (years 6–8), and year 9 (the 1st year of high school for those promoted each year). Academic, parental, and personal resources condition dropout prospects at each time point, with resources measured early in children's schooling forecasting dropout almost as well as those from later in children's schooling. Additionally, evidence is presented that resources add on to one another in moderating dropout risk, including risk associated with family SES. These patterns are discussed in terms of a life course view of the dropout process.

The importance of marriage timing for educational attainment is examined for a national sample of young men and women. In attempting to deal with technical deficiencies in earlier research on this issue, we distinguish schooling obtained prior to marrying from that obtained afterward and adjust both measures for the age-grading of school enrollment patterns. We focus on the implications of marriage timing for schooling obtained after one marries. We conclude that marrying early is detrimental to the educational attainments of women but of little or no consequence for men. We also demonstrate that formulations of the age at marriage-educational attainment relationship similar to those employed in other studies would have led to quite different conclusions.

Status attainment research has been characterized by the evaluation of analytic models of increasing complexity. This project replicates one of the Wisconsin "social-psychological" models of socioeconomic achievement with 15-year longitudinal data for a national sample of males first sampled in 1955 as high school sophomores and followed up in 1970. Interpersonal and subjective school variables are found to mediate a substantial part of the effects of ability and social origins on later status outcomes, indicating complex processes quite similar to those demonstrated in the original Wisconsin analysis. Minor differences in results between the two inquiries robably reflect differences in sample composition and research design.

The socioeconomic consequences of qualitative variations in educational experiences are evaluated for a sample of young adult males who were first surveyed in 1955 as high school sophomores and followed up in 1970. Models of institutional influence and of within-school processes are developed for both secondary and postsecondary education to integrate and refine the literatures on school effects and returns to schooling. Rather impressive occupational status and earnings differentials are associated with gross school-to-school differences and with qualitative differences in educational experiences within institutions. Secondary school characteristics and experiences weigh particularly upon the market outcomes of youth who terminated formal schooling at high school graduation. We suggest that the traditional use for quantitative indices of schooling (years of school completed or certification levels) in assessing the market consequences of investments in education needs to be supplemented by information on qualitative variations in educational experiences. Additionally, the likelihood that school experiences may have quite different implications for selected target populations deserves further consideration. The simplistic assumption implicit in much of the school-effects literature that institutional effects are homogeneous may actually mask quite important consequences for certain students.

The transition from "home child" to "school child" is an important social milestone and encompasses a life period that has not received as much attention as it may deserve. Poor black children, who are those with the most social interaction disabilities, seem particularly vulnerable in the early part of this transition. A further complication is that "summer learning" helps mainly well-off children, and blacks in the population-at-large are less likely to be well off than whites. Although schools do seem to be making up for the dearth of academic socialization resources in many young children's households, and in this sense are most beneficial for those who need them most, more work is needed on why schools are not filling the bill as well for the neediest blacks as they are for the neediest whites.

Optimization of SOFC electrodes requires detailed insight into their electrochemical processes and rate limiting steps. The impedance spectroscopic investigation of symmetrical cells with two equal electrodes on a solid electrolyte measures not only the area-specific polarization resistance of the electrodes, but physically motivated equivalent circuit modelling and fitting also gives detailed insight into the electrochemical reaction mechanisms and rate limiting processes. In this paper, we give a comprehensive introduction into impedance modeling of porous electrodes and show that a transmission-line type equivalent circuit that is mathematically analogous to the Adler-Lane-Steele model is perfectly applicable to Ni+YSZ cermet anodes. The equivalent circuit fit yields the effective ionic conductivity of the cermet structure, which enables determination of the YSZ phase tortuosity factor. In addition, we can measure the characteristic electrochemically active thickness of the anodes, which gives a direct guideline for the optimal thickness of the fine grained anode active layer in a full SOFC.

Metal-supported solid oxide fuel cells (MSCs) are promising candidates for non-stationary applications like auxiliary power units (APUs) in heavy duty trucks or range extender systems for battery electric vehicles. Due to limited space available for integrating such systems especially in passenger cars, achieving high power density of MSCs is essential. The MSC concept of Plansee, Austria was stepwise optimized by improved processing of the electrodes and tailoring of the interfaces. Variations of cathode composition and sintering conditions were investigated. Using LSC or LSC/GDC cathodes and Ni/GDC anodes with higher electrochemically active volume increased the cell performance significantly. Moreover, reducing the electrolyte to 2 µm resulted in further improvement of the performance. Finally, preliminary results of long-term operation of the Plansee MSC for more than 1.000 h at 700 °C and 300 mA cm-2, as well as post-mortem analyses, are presented.

A novel sintering approach was developed in order to overcome the issue of insufficient adherence of (La,Sr)(Co,Fe)O3type cathodes in metal-supported solid oxide fuel cells (MSCs). Investigation of the phase stability of the perovskite structure at high temperature in various atmospheres with low oxygen partial pressures provided the basis for the development of a specific sintering procedure. After detailed investigation of the layer adherence, time dependent mechanical integrity and reversibility of phase transformations, metal-supported cells with cathodes sintered before cell operation (ex-situ sintering) could be produced reliably and were electrochemically characterized in single cell measurements. The novel sintering approach of such cathodes resulted in a significantly enhanced mechanical stability of the cathode layers. The adherence of the cathode to the electrolyte was considerably stronger, which is a substantial improvement in comparison with state-of-the-art MSCs. Furthermore, the electrochemical measurements revealed a beneficial effect regarding the cell performance.

To demonstrate the performance and reliability of MSCs (Metal Supported SOFCs), a systematic electrochemical characterization on button cells has been performed. The cell conditioning during the first heating-up is described in detail, since there is a significant difference to ESCs (Electrolyte Supported Cell) and ASCs (Anode Supported Cell). The focus of the present work is to show the influence of different anode materials, gas-flow rates, and operation temperatures on recorded i-V-curves. In some cases, fuel utilization rates were used, which are higher than commonly applied in button cell experiments. However, under these harsh conditions, the anode and the metal substrate must handle e.g. high humidity.This paper summarizes recent results on (i) manufacturing, (ii) appropriate test procedures, (iii) electrochemical testing, and (iv) influence of different anode layer materials for MSCs.

Photo-electrochemical cells based on aqueous electrolytes have been heavily investigated for their potential to convert light into chemical energy. In contrast, very little is known on the possibility of transferring photon energy into chemical energy in high temperature solid state electrochemical cells. This is true despite the fact that solid electrolyte based systems can be operated very successfully as fuel and electrolysis cells (SOFCs/SOECs). Here, we report results on the interaction of mixed conducting oxides with light in cells using oxide ion conductors and operating at 350-500°C. One type of system contains a high temperature solar cell based on SrTiO3and LaCrO3. It allows oxygen pumping and thus chemical energy storage under UV light. In another type of system UV light produces a time dependent voltage that includes two processes potentially also enabling energy storage: First, again a photovoltaic effect is present; second, the illuminated mixed conducting oxide changes its stoichiometry and thus leads to a battery type (Nernstian) voltage.

Model-type thin films of Gd doped and Gd/Mn co-doped ceria were investigated by means of impedance spectroscopy in a humid H2atmosphere. A novel measurement technique for microelectrodes with interdigitating Pt current collectors was employed. This method allows a separation of the different elementary processes contributing to the electrode impedance. After annealing at 650°C in humid H2atmosphere, an increase in catalytic activity of Gd/Mn co-doped ceria was observed.

Micro-patterned Ni thin films with well-defined 2D-structures are useful to examine electrochemical reaction kinetics of SOFC anodes. In this work, an electrode preparation method is developed yielding stable Ni pattern electrodes on YSZ, which facilitate long term measurements. Moreover, these stable electrodes allowed investigating the effect of the YSZ substrate orientation on the polarization resistance and interface capacitance. Statistical analysis of data obtained from 3 different substrates revealed no significant difference in polarization resistances and no significant difference in interface capacitance between single crystalline substrates (α=0.05). Also, the effect of hydrogen sulfide on the polarization resistance was examined and the results are qualitatively equivalent to findings on cermet electrodes.

Mixed conducting cathodes for solid oxide electrolysis cells (SOECs) offer a promising alternative to the nowadays used Ni/YSZ cermet. Here, the water splitting kinetics of mixed conducting perovskite-type La0.6Sr0.4FeO3-δ(LSF) thin film electrodes was investigated in humid reducing atmospheres at 600 – 650 °C. Under equilibrium conditions an area specific surface resistance of ca. 15 Ωcm² was obtained on freshly prepared electrodes. Upon cathodic polarization of more than 20 mV a strong decrease of the surface resistance was observed. This acceleration of the water splitting kinetics was accompanied by the formation of metallic iron particles on the LSF surface, which was observed by means of near-ambient pressure XPS experiments.

Metal-supported solid oxide fuel cells (MSCs) offer various potentials like cost reduction and abuse tolerance, which make them attractive for mobile applications such as auxiliary power units (APUs). The implementation of the metallic substrate requires specific adaption of SOFC processing technologies since sintering of functional layers at high temperatures under oxidizing atmosphere is restricted by the substrate. Therefore, one of the current challenges is the development of an anode layer, which can be sintered under reducing atmospheres, which improves i.a. the performance, the ageing behavior and the ability of the anode to withstand sulfur contaminations of the fuel gas. In the present work, a new anode concept is presented, which is based on a Ni/GDC cermet replacing the established Ni/YSZ cermet. The sintering study is supported by some preliminary results of characterizing the electrochemical performance of the Ni/GDC anodes by impedance spectroscopy. In addition, a thin GDC layer is currently used as diffusion barrier layer between the anode and the metallic substrate. A systematic study of the stability of this barrier layer under anode sintering conditions is given.

Examines the pros and cons of flunking and retaining children in the school. Opposing views on the advantages of child's retention in school; Alternative options for retention; Social promotion as injustice to child.