Microencapsulation of phosphogypsum into a sulfur polymer matrix: physico-chemical and radiological characterization

The aim of this work is to prepare a new type of phosphogypsum-sulfur polymer cements (PG-SPC) to be utilised in the manufacture of building materials. Physico-chemical and radiological characterization was performed in phosphogypsum and phosphogypsum-sulfur polymer concretes and modeling of exhalation rates has been also carried out. An optimized mixture of the materials was obtained, the solidified material with optimal mixture (sulfur/phosphogypsum = 1:0.9, phosphogypsum dosage = 10-40 wt.%) results in highest strength (54-62 MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference value in the most international regulations and; therefore, these cements can be used without radiological restrictions in the manufacture of building materials. Under normal conditions of ventilation, the contribution to the expected radon indoor concentration in a standard room is below the international recommendations, so the building materials studied in this work can be applied to houses built up under normal ventilation conditions.Additionally, and taking into account that the PG is enriched in several natural radionuclides as ²²⁶Ra, the leaching experiments have demonstrated that environmental impact of the using of SPCs cements with PG is negligible.     

Survey of Psychological Services to Clients With Disabilities: The Need for Awareness.

Objective: To identify barriers to, strategies for, and supports for psychological services for clients with disabilities. Design: Mail survey. Participants: Four hundred eighty-one psychologists who were American Psychological Association members. Measure: A survey that ascertained psychologists' perceptions of access barriers, success factors, and support needs in providing services to clients with disabilities, as well as experiences with bias or sensitivity. Results: Barriers to service provision include funding, accessibility, lack of provider knowledge, limited training in disability issues and services, and lack of sensitivity. Conclusions: Additional training for psychologists in disability issues, legal requirements regarding public accommodations, and disability resources is needed. Psychologists with disabilities may be an important resource. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethical issues in psychotherapy research: Problems in a collaborative clinical trials study.

Addresses ethical issues of psychotherapy research in the context of the pilot study phase of a large collaborative study that examined 2 forms of brief psychotherapy (cognitive-behavior and interpersonal) for the treatment of depression. The issues include those that emanated from the use of a clinical trials design (e.g., random treatment assignment, control conditions) and those derived from the collaborative nature of the research (e.g., comprehensibility of informed consent forms, security of data transmission). (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biological response of human bone marrow stromal cells to sandblasted titanium nitride-coated implant surfaces

Titanium nitride (TiN) coating has been proposed as an adjunctive surface treatment aimed to increase the physico-mechanical and aesthetic properties of dental implants. In this study we investigated the biological response of primary human bone marrow stromal cells (BMSC) to TiN-coated sandblasted (TiN-SB) compared to uncoated sandblasted (SB) surfaces. SB and TiN-SB disks were qualitatively and quantitatively analyzed by atomic force microscopy. BMSC were obtained from healthy donors and their adhesion and proliferation on the titanium disks were evaluated by scanning electron microscopy and viability assay. The osteoblastic differentiation, in terms of alkaline phosphatase activity, osteocalcin synthesis, and extracellular mineralization, was assessed by specific immunoenzymatic or spectrophotometric assays. No difference (P > 0.05) between TiN-SB and SB disks was found in terms of any of the investigated parameters. TiN-coating showed to maintain the topographical characteristics of sandblasted titanium surfaces and their biological affinity toward bone precursors.     

Atomic Structures of [0\bar{1}10] Symmetric Tilt Grain Boundaries in Hexagonal Close-Packed (hcp) Crystals

Molecular dynamics simulation and interface defect theory are used to determine the relaxed equilibrium atomic structures of symmetric tilt grain boundaries (STGBs) in hexagonal close-packed (hcp) crystals with a $ [0\bar{1}10] $ tilt axis. STGBs of all possible rotation angles ?? from 0?deg to 90?deg are found to have an ordered atomic structure. They correspond either to a coherent, defect-free boundary or to a tilt wall containing an array of distinct and discrete intrinsic grain boundary dislocations (GBDs). The STGBs adopt one of six base structures, $ P_{B}^{(i)} $ , i?=?1, ??, 6, and the Burgers vector of the GBDs is related to the interplanar spacing of the base structure on which it lies. The base structures correspond to the basal plane (???=?0?deg, $ P_{B}^{(1)} $ ); one of four minimum-energy, coherent boundaries, $ (\bar{2}111),\;(\bar{2}112),\;(\bar{2}114) $ , and $ (\bar{2}116)\;\left( {P_{B}^{(2)} - P_{B}^{(5)} } \right) $ ; and the $ \left( {11\bar{2}0} \right) $ plane (???=?90?deg, $ P_{B}^{(6)} $ ). Based on these features, STGBs can be classified into one of six possible structural sets, wherein STGBs belonging to the same set i contain the same base boundary structure $ P_{B}^{(i)} $ and an array of GBDs with the same Burgers vector $ b_{\text{GB}}^{(i)} $ , which vary only in spacing and sign with ??. This classification is shown to apply to both Mg and Ti, two metals with different c/a ratios and employing different interatomic potentials in simulation. We use a simple model to forecast the misorientation range of each set for hcp crystals of general c/a ratio, the predictions of which are shown to agree well with the molecular dynamics (MD) simulations for Mg and Ti.     

Use of Organoclay as Secondary Containment for Gasoline Storage Tanks

Conventional clay liners, which are widely used as hydraulic barriers to water, have been shown to be adversely affected by organic fluids. However, the addition of quaternary amines into bentonite greatly enhances its compatibility with organic fluids and thus allows the clay barrier technology to be extended to the treatment of organic contaminants. In this study, an organically modified clay was studied for use as a secondary containment for gasoline underground storage tanks. Free swelling and hydraulic conductivity tests were performed on organoclay, pure bentonite, and natural soils. Results show that organoclay has a large swelling capacity in gasoline, whereas bentonite and natural soils shrink when immersed in gasoline. The hydraulic conductivities of bentonite and natural soils to gasoline are 2–5 orders of magnitude higher than that to water. In contrast, the hydraulic conductivity decreases by 2 orders of magnitude for organoclay and this low value can be maintained even under freeze-thaw and dry-wet cycles.     

Ain't misbehavin': The effects of age and intentionality on judgments about misconduct.

In 2 person perception experiments, young and older perceivers read a scenario about a young or old female target who leaves a store without paying for a hat. In Experiment 1, the target claims she forgot she was wearing the hat when questioned by the manager. Perceivers thought the manager would have greater sympathy, less anger, and would recommend less punishment when the target was old. In Experiment 2, the target clearly forgot to pay for the hat, clearly stole it, or had ambiguous intentions. In the ambiguous condition, perceivers attributed the young target's behavior more to stealing and the old target's behavior more to forgetting. In the forget condition, young perceivers had equal sympathy for the young and old targets and held them similarly responsible, but older perceivers had greater sympathy for the forgetful old target and held her less responsible than they did the forgetful young target. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imagining stereotypes away: The moderation of implicit stereotypes through mental imagery.

Research on implicit stereotypes has raised important questions about an individual's ability to moderate and control stereotypic responses. With few strategies shown to be effective in moderating implicit effects, the present research investigates a new strategy based on focused mental imagery. Across 5 experiments, participants who engaged in counterstereotypic mental imagery produced substantially weaker implicit stereotypes compared with participants who engaged in neutral, stereotypic, or no mental imagery. This reduction was demonstrated with a variety of measures, eliminating explanations based on response suppression or shifts in response criterion. Instead, the results suggest that implicit stereotypes are malleable, and that controlled processes, such as mental imagery, may influence the stereotyping process at its early as well as later stages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparisons of U.S. and Japanese first graders' cognitive representation of number and understanding of place value.

Examined the argument that differences in mathematics performance between students from the United States and Japan may be due, at least in part, to fundamental variations in cognitive representation of number that result from differences in numerical language characteristics that differentiate the two groups. Twenty-four first graders from each country participated in the study. The results suggest that first graders in the United States and Japan differ in their cognitive representation of number, and that this difference may positively affect the Japanese children's understanding of place value and their subsequent mathematics performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)