Micro-solid-phase extraction (µ-SPE) of organophosphorous pesticides from wheat followed by LC-MS/MS determination

A rapid, selective and effective method of extraction, clean-up and concentration of organophosphorous pesticides from wheat followed by electrospray (ESI) LC-MS/MS analysis was developed. The μ-SPE (micro-solid-phase extraction) procedure resulted in good analytical performance and reduced at the same time matrix effects, analysis time and solvent consumption. Limits of detection (LODs) and quantification (LOQs) were in the range of 0.3–10 and 1–30 μg kg^?1, respectively, with good reproducibility (RSD ≤ 13.8) and recoveries between 75% and 109%. Coefficients of determination (r²) were greater than 0.996 for the studied pesticides. Despite the reduced sorbent bed mass of μ-SPE tips (4.2 mg), the analytical data showed that no saturation phenomena occurs in the tested range of concentration both for single compounds and mixtures. Several real samples were analysed and the concentrations of the selected pesticides were found to be below the respective maximum residue limit (MRLs).     

Spatial ability: A neglected dimension in talent searches for intellectually precocious youth.

Students identified by talent search programs were studied to determine whether spatial ability could uncover math-science promise. In Phase 1, interests and values of intellectually talented adolescents (617 boys, 443 girls) were compared with those of top math-science graduate students (368 men, 346 women) as a function of their standing on spatial visualization to assess their potential fit with math-science careers. In Phase 2, 5-year longitudinal analyses revealed that spatial ability coalesces with a constellation of personal preferences indicative of fit for pursuing scientific careers and adds incremental validity beyond preferences in predicting math-science criteria. In Phase 3, data from participants with Scholastic Aptitude Test (SAT) scores were analyzed longitudinally, and a salient math-science constellation again emerged (with which spatial ability and SAT-Math were consistently positively correlated and SAT-Verbal was negatively correlated). Results across the 3 phases triangulate to suggest that adding spatial ability to talent search identification procedures (currently restricted to mathematical and verbal ability) could uncover a neglected pool of math-science talent and holds promise for refining our understanding of intellectually talented youth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of spatial ability on gender differences in mathematics college entrance test scores across diverse samples.

The relationship between mental rotation ability and gender differences in Scholastic Aptitude Test-Math (SAT-M) across diverse samples was investigated. Talented preadolescents, college students and high- and low-ability college-bound youths, totaling 760, were administered the Vandenberg Mental Rotation Test. Gender comparisons showed male outperforming female students in both mental rotation and SAT-M for all 3 high-ability groups but not for the low-ability group. For all female samples, mental rotation predicted math aptitude even when SAT-Verbal was entered first into the regression. For male samples, the relationship varied as a function of sample. When mental rotation ability was statistically adjusted for, the significant gender difference in SAT-M was eliminated for the college sample and the high-ability college-bound students. This suggests that spatial ability may be responsible in part for mediating gender differences in math aptitude among these groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Naive optics: Understanding the geometry of mirror reflections.

Paper-and-pencil tasks showed that many university students believed that when laterally approaching a mirror, they would see a reflection in the mirror before it was geometrically possible. Participants failed to adequately factor in the observer's location in the room. However, when asked about the behavior of a ray of light, participants knew about the law of reflection. No differences between psychology and physics students were detected, suggesting that the phenomenon is widespread and refractory to training. The findings were replicated with observers making judgments about image locations in a real room using a pretend mirror. Possible heuristics about mirror reflection that might explain the data are discussed. Naive optics is a promising venue to further knowledge of how observers understand basic laws of physics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of high school coursework and time on SAT scores.

Two studies were conducted to determine (1) whether differential educational experiences contribute to differential growth on Scholastic Aptitude Test (SAT) scores and (2) whether such experiences must occur over a long rather than a short duration to have impact. Specific content knowledge in mathematics/science and verbal areas taught during a short time interval did not increase SAT-M and SAT-V scores even when the content was of the type required to solve SAT problems. Exposure to academically rigorous educational experiences over a long time period (5 yrs) did relate to the development of abilities measured by SAT. In addition, students who experienced very large gains on SAT over this 5-yr period, in comparison with students with small gains, were achieving better in a more rigorous program of high school courses in mathematics and science for the SAT-M and in verbal areas for the SAT-V. Results support the position that educational experiences over time influence SAT scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multi-touch table system for medical visualization: application to orthopedic surgery planning

Medical imaging plays a central role in a vast range of healthcare practices. The usefulness of 3D visualizations has been demonstrated for many types of treatment planning. Nevertheless, full access to 3D renderings outside of the radiology department is still scarce even for many image-centric specialties. Our work stems from the hypothesis that this under-utilization is partly due to existing visualization systems not taking the prerequisites of this application domain fully into account. We have developed a medical visualization table intended to better fit the clinical reality. The overall design goals were two-fold: similarity to a real physical situation and a very low learning threshold. This paper describes the development of the visualization table with focus on key design decisions. The developed features include two novel interaction components for touch tables. A user study including five orthopedic surgeons demonstrates that the system is appropriate and useful for this application domain.     

Peroxyacetic Acid Oxidation of Olefins and Alkanes Catalyzed by a Dinuclear Manganese(IV) Complex with 1,4,7-trimethyl-1,4,7-triazacyclononane

Natural terpenes, (−)-limonene and (+)-carvone, can be epoxidized by peroxyacetic acid (PAA) at room temperature if a dinuclear manganese(IV) complex with 1,4,7-trimethyl-1,4,7-triazacyclononane (L), [Mn₂L₂O₃] [PF₆]₂, is used as a catalyst. The total yield of the epoxides based on the consumed olefins are 97 and 95%, respectively. A kinetic study of the dec-1-ene and cyclohexane oxygenations including the investigation of their simultaneous competitive oxidation was carried out. The olefin epoxidation rate does not depend on dec-1-ene concentration and the dec-1-ene concentration does not affect the rate of cyclohexane oxidation. The cyclohexane oxidation rate is proportional to the alkane concentration. The kinetic analysis led to the conclusion that two species X ₁ and X ₂ are generated in the system, and there is no their mutual interconversion. The rate equation for the dec-1-ene epoxidation was proposed: W = k ₊₁[cat][PAA], where cat is the initial manganese complex or its derivative, and the constant was determined: k ₊₁ = 3.5 mol⁻¹ dm³ s⁻¹. Species X ₁ is apparently an effectively epoxidizing manganese peroxo derivative whereas species X ₂ is an alkane hydroxylating manganese oxo complex.     

Therapeutic Strategies To Counteract Antibiotic Resistance in MRSA Biofilm-Associated Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the leading causes of persistent human infections. This pathogen is widespread and is able to colonize asymptomatically about a third of the population, causing moderate to severe infections. It is currently considered the most common cause of nosocomial infections and one of the main causes of death in hospitalized patients. Due to its high morbidity and mortality rate and its ability to resist most antibiotics on the market, it has been termed a “superbug”. Its ability to form biofilms on biotic and abiotic surfaces seems to be the primarily means of MRSA antibiotic resistance and pervasiveness. Importantly, more than 80 % of bacterial infections are biofilm-mediated. Biofilm formation on indwelling catheters, prosthetic devices and implants is recognized as the cause of serious chronic infections in hospital environments. In this review we discuss the most relevant literature of the last five years concerning the development of synthetic small molecules able to inhibit biofilm formation or to eradicate or disperse pre-formed biofilms in the fight against MRSA diseases. The aim is to provide guidelines for the development of new anti-virulence strategies based on the knowledge so far acquired, and, to identify the main flaws of this research field, which have hindered the generation of new market-approved anti-MRSA drugs that are able to act against biofilm-associated infections     

Preparation and characterization of safe microparticles based on xylan

This work describes the preparation and evaluation of safe xylan-based microparticles prepared by cross-linking polymerization using sodium trimetaphosphate. The resulting microparticles were evaluated for morphology, particle size, polymer-cross-link agent interaction, and in vitro toxicity. The microparticles showed narrow monodisperse size distributions with their mean sizes being between 3.5 and 12.5?µm in dried state. FT-IR analyzes confirmed the interaction between sodium trimetaphosphate and xylan during the cross-linking process with formation of phosphate ester bonds. Additionally, the X-ray diffraction patterns and FT-IR analyzes suggested that little or no cross-linking agent remained inside the microparticles. Furthermore, the in-vitro studies using Artemia salina and human erythrocytes revealed that the microparticles are not toxic. Therefore, the overall results suggest that these xylan microparticles can be used as a platform for new drug delivery system.