Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.     

University environment as a mediator of Latino ethnic identity and persistence attitudes.

The authors examined whether the perception of the university environment mediated the relationship between ethnic identity and persistence attitudes of Latino college students. Participants were 175 Latino college students who attended a primarily White university. The results supported the hypothesized mediating role of the university environment. Higher Latino ethnic identity was associated with perceiving a more negative university environment and feeling less committed to finishing college. In turn, perception of a negative college environment was associated with feeling less committed to finishing college. When perception of the university environment was removed, no significant relationship was found between ethnic identity and persistence attitudes, indicating that it is the perceived context that influences Latino college students' persistence attitudes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Local structures of perovskite dielectrics and ferroelectrics via pair distribution function analyses

The pair distribution function (PDF) method provides a useful way of characterizing the diverse and richly complex local structures in perovskite dielectric and ferroelectric materials. This review provides a basic introduction to the PDF method and the underpinning total scattering experiments. Results are reviewed from ex situ PDF that describe composition-dependent local structures and “box-car” fitting approaches to characterize longer range structures and length-scale effects. In situ PDF studies are reviewed that are sensitive to the local structural response of perovskites to temperature, electric field, and pressure. The dynamic pair-density function is also briefly introduced as well as examples of local structure analysis using combined inputs, e.g., extended X-ray absorption fine structure spectroscopy, Raman spectroscopy, and first-principle calculations. These advances in advanced and integrated analysis, dynamics, and in situ methods will enable the PDF method to continue enlightening dielectrics and ferroelectrics research in the coming decades.     

Exploring relationships of spring green-up to moisture and temperature across Wyoming,U.S.A

Vegetation green-up signals the timing of available nutritious plants and shrubs providing high-quality forage for ungulates. In this study, we characterized spatial and temporal patterns of spring phenology and explored how they were related to preceding temperature and moisture conditions. We tested correlations between late winter weather and indicators of the onset and the length of the spring growing period with 250-m resolution time-series satellite data (2001 – 2013) for Wyoming, USA. In western Wyoming mountains, drier and warmer conditions during late winter were associated with earlier spring green-up onset of growth in forests, shrubs, and grasses. In the northeast mountains, onset of spring correlated positively with preceding warmer temperatures, but not with precipitation. In most basin and plains shrublands and grasslands, spring onset was not correlated with temperature, although earlier onset of spring was correlated with drier conditions in 25% of shrub/scrub areas. Results about the length of spring were less definitive, with warmer temperatures related to longer green-up time for 12–30% of the land cover in western mountains but to shorter green-up time periods for 10–20% of the grasses and shrubs in basins and plains. Complex phenological patterns are likely to affect ungulate foraging behaviour on a local scale.     

Introduction: Psychoanalysis and sexuality.

Articles originally presented at the 18th annual spring meeting of the Division of Psychoanalysis of the American Psychological Association collected in an issue of Psychoanalytic Psychology are introduced. The title of the conference was "Psychoanalysis and sexuality: Reflections on an old love affair," and articles selected address aspects of this theme. Included in the issue are contributions from R. Schafer (1999a, 1999b), O. Renik (1999), D. Kriegman (1999), D. Schwartz (1999), M. O. Slavin (1999), H. G. Russ (1999), and J. K. Ogden (1999). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Diffuse Axonal Injury on Speed of Information Processing Following Severe Traumatic Brain Injury.

To test the hypothesis that slowed information processing in traumatic brain injury is related to diffuse axonal injury (DAI), the authors compared 10 patients with predominant DAI (diffuse group) and minimal DAI (mixed injury group) on the Symbol Digit Modalities Test, simple and choice reaction time, Trail Making Tests A and B, and the Stroop Neuropsychological Screening Test. The diffuse group was slower than the mixed injury and control groups on basic speed of processing tasks. This difference was not apparent on complex speeded tasks once basic speed of processing was controlled for. The diffuse group's slower speed of processing was not accounted for by differences in injury severity, age, or time postinjury. The diffuse group showed greater recovery over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive processes, anxiety, and performance on doctoral dissertation oral examinations.

In an effort to explore evaluation anxiety in a naturalistic setting, this study examined the relationships among anxiety, thoughts, self-efficacy, and performance of 37 students defending their doctoral dissertations. After the orals, faculty examiners rated each student's performance and level of anxiety. Analyses showed that the state-of-mind ratio (ratio of positive thoughts to positive-plus-negative thoughts) appeared to be a more important contributor to anxiety than did self-inefficacy to control thoughts. Although faculty ratings of anxiety were significantly related to their ratings of performance, S's own reports of anxiety and their thoughts during orals were not predictive of performance. The strongest predictors of orals performance were graduate grade point average (GPA) and committee ratings of the quality of the dissertation and of the student's work in the doctoral program before the dissertation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pilot-scale demonstration of phytofiltration for treatment of arsenic in New Mexico drinking water

Arsenic contamination of drinking water poses serious health risks to millions of people worldwide. To reduce such risks, the United States Environmental Protection Agency recently lowered the Maximum Contaminant Level for arsenic in drinking water from 50 to 10 microgL(-1). The majority of water systems requiring compliance are small systems that serve less than 10,000 people. Current technologies used to clean arsenic-contaminated water have significant drawbacks, particularly for small treatment systems. In this pilot-scale demonstration, we investigated the use of arsenic-hyperaccumulating ferns to remove arsenic from drinking water using a continuous flow phytofiltration system. Over the course of a 3-month demonstration period, the system consistently produced water having an arsenic concentration less than the detection limit of 2 microgL(-1), at flow rates as high as 1900 L day(-1) for a total treated water volume of approximately 60,000 L. Our results demonstrate that phytofiltration provides the basis for a solar-powered hydroponic technique to enable small-scale cleanup of arsenic-contaminated drinking water.     

Chemorheological changes in crosslinked epoxy resins subjected to large strains

Chemorheological changes in epoxy resins subjected to large strains while heated were observed earlier, but the subject was not treated quantitatively. This paper describes the investigation of an epoxy resin—Epon 826, of known chemical, structure, crosslinked with two different amines. By means of a simple calibrated apparatus, the epoxide samples were subjected to large strains in a non-oxidizing atmosphere and in air. They were heated to different temperatures for various times; the results were compared with data obtained from unstrained samples kept in otherwise the same conditions. The results show a linear-logarithmic relation between the torsion modulus, G₍₁₀₎ and the time of applied strain at a certain temperature and also a linear relation between G₍₁₀₎, and 1/T°K, both above T₍₁₀₎. The results obtained in swelling experiments support the data from 10 sec torsional modulus vs temperature measurements. An increase in the amount of solubles and in M_c is observed on extending the time of heating. A clear difference in properties between the strained and unstrained samples, kept in otherwise the sane conditions, is observed and the contribution of the applied strain to chemorheology has been shown. Both systems of crosslinked Epon 826 showed the same general behavior, although the specific data were different.