Learners' questions and comprehension in a tutoring setting.

Three experiments, presented within the framework of Activity Theory, deal with the relationship between adult learners' questions and subsequent comprehension in a tutorial learning setting. Students were first given verbal instructions (acquisition) to a novel card game and then asked to play one hand with the teacher (implementation). In Experiment 1, there was no correlation between number of questions asked during acquisition and comprehension, but questions during implementation were negatively correlated with comprehension. In Experiment 2, learners whose questions were answered during acquisition scored higher than those whose questions were not answered. In Experiment 3, learners whose questions were answered during implementation showed greater gains in comprehension than those whose questions were answered during acquisition. Individual differences in question-asking during implementation but not acquisition were significantly related to comprehension. The results confirm the view that questions answered during knowledge implementation more effectively aid comprehension than those answered during acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular Subtyping of Invasive Breast Cancer Using a PAM50-Based Multigene Expression Test-Comparison with Molecular-Like Subtyping by Tumor Grade/Immunohistochemistry and Influence on Oncologist’s Decision on Systemic Therapy in a Real-World Setting

In intermediate risk hormone receptor (HR) positive, HER2 negative breast cancer (BC), the decision regarding adjuvant chemotherapy might be facilitated by multigene expression tests. In all, 142 intermediate risk BCs were investigated using the PAM50-based multigene expression test Prosigna® in a prospective multicentric study. In 119/142 cases, Prosigna® molecular subtyping was compared with local and two central (C1 and C6) molecular-like subtypes relying on both immunohistochemistry (IHC; HRs, HER2, Ki-67) and IHC + tumor grade (IHC+G) subtyping. According to local IHC, 35.4% were Luminal A-like and 64.6% Luminal B-like subtypes (local IHC+G subtype: 31.9% Luminal A-like; 68.1% Luminal B-like). In contrast to local and C1 subtyping, C6 classified >2/3 of cases as Luminal A-like. Pairwise agreement between Prosigna® subtyping and molecular-like subtypes was fair to moderate depending on molecular-like subtyping method and center. The best agreement was observed between Prosigna® (53.8% Luminal A; 44.5% Luminal B) and C1 surrogate subtyping (Cohen’s kappa = 0.455). Adjuvant chemotherapy was suggested to 44.2% and 88.6% of Prosigna® Luminal A and Luminal B cases, respectively. Out of all Luminal A-like cases (locally IHC/IHC+G subtyping), adjuvant chemotherapy was recommended if Prosigna® testing classified as Prosigna® Luminal A at high / intermediate risk or upgraded to Prosigna® Luminal B.     

Characterization of expression of a plant oleate desaturase in yeast

We have expressed the oleate desaturase gene of Arabidopsis thaliana in Saccharomyces cerevisiae by means of a galactose-inducible promoter. Transfer of yeast cells to galactose-containing media and growth at 30°C resulted in the production of active oleate desaturase, as shown by the appearance of the diunsaturated octadecadienoic acid (18:2) and hexadecadienoic acid (16:2). The highest level of these two fatty acids was 46.2%. In induced cultures, 18:2 appeared before 16:2, and we show that both of these fatty acids were present first on phosphatidylcholine and then appeared in other phospholipids and a neutral lipid fraction. We raised antibodies against the C-terminal 100 amino acids of oleate desaturase and demonstrated that this protein was in the microsomal fraction of induced cells.     

Tobacco etch virus protease: mechanism of autolysis and rational design of stable mutants with wild-type catalytic proficiency

Because of its stringent sequence specificity, the catalyticdomain of the nuclear inclusion protease from tobacco etch virus(TEV) is a useful reagent for cleaving genetically engineeredfusion proteins. However, a serious drawback of TEV proteaseis that it readily cleaves itself at a specific site to generatea truncated enzyme with greatly diminished activity. The rateof autoinactivation is proportional to the concentration ofTEV protease, implying a bimolecular reaction mechanism. Yet,a catalytically active protease was unable to convert a catalyticallyinactive protease into the truncated form. Adding increasingconcentrations of the catalytically inactive protease to a fixedamount of the wild-type enzyme accelerated its rate of autoinactivation.Taken together, these results suggest that autoinactivationof TEV protease may be an intramolecular reaction that is facilitatedby an allosteric interaction between protease molecules. Inan effort to create a more stable protease, we made amino acidsubstitutions in the P2 and P1' positions of the internal cleavagesite and assessed their impact on the enzyme's stability andcatalytic activity. One of the P1' mutants, S219V, was not onlyfar more stable than the wild-type protease (~100-fold), butalso a more efficient catalyst.     

Assessment of Post-Earthquake Fire Behavior of a Steel MRF Building in a Low Seismic Region

International Journal of Steel Structures - Building-level response to post-earthquake fire hazards in steel buildings has been assessed using primarily two-dimensional analyses of the lateral...     

Micron-Scale Soft Actuators Fabricated from Multi-Shell Polystyrene Particle-Gold Nanoparticle Nanohybrids

Actuators made of soft matter are needed for a variety of fields ranging from biomedical devices to soft robotics to microelectromechanical systems. While there are a variety of excellent methods of soft actuation known, the field is still an area of intense research activity as new niches and needs emerge with new technology development. Here, a soft actuation system is described, based on a core-multi-shell particle, which moves via photothermal expansion. The system consists of a novel polystyrene-based thermally expandable microsphere, with a secondary shell of a silicate-silane graft copolymer, to which gold nanoparticles are covalently linked. The gold nanoparticles act as photothermal nano-transducers, converting light energy into the thermal energy necessary for microsphere expansion, which in turn results in material movement. Actuation is shown in isolated particles in thermal and photothermal regimes using metal ceramic heaters or 520 nm laser illumination, respectively. Macroscale actuation is demonstrated by making a composite material of particles suspended in the transparent elastomer polydimethylsiloxane. The sample demonstrates an inchworm-like movement by starting from an arched geometry. Overall, this work describes a new particle-based actuation method for soft materials, and demonstrates its utility in driving the movement of a composite elastomer.     

1H‐decoupling and Isotopic Labeling for the Measurement of the Longitudinal Relaxation Time of Hyperpolarized 13C‐Methylenes in Choline Analogs

The T₁ of a hyperpolarized site in solution is a key parameter that determines the time‐window in which its NMR signals are observable. For ¹³C sites adjacent to protons, ¹H‐decoupling has been shown to increase the hyperpolarized signal resolution and SNR. Additionally, polarization transfer to protons has shown utility in increasing the sensitivity of detection. However, ¹H‐decoupling could lead to a change in the decay rate of a hyperpolarized ¹³C site. Here we tested this possible effect in a case where the protons are directly bound to an sp³ hyperpolarized ¹³C site (using [1,2‐¹³C₂]choline) and ¹H‐decoupling was applied continuously throughout the hyperpolarized decay measurement. We found that ¹H‐decoupling did not lead to any significant changes in the ¹³C polarization decay time but did result in the expected collapse of J‐coupling and produced sharper signals. This result suggested that ¹H‐decoupling did not affect the decay rate of hyperpolarized sp^{3 13}C sites. The deuterium‐substitution approach (using [1,1,2,2‐D₄,1‐¹³C]choline) showed a dramatic prolongation of T₁. Upper bounds on the T₁ of all investigated sites were calculated.     

A rheometry method to assess the evaporation-induced mechanical strength development of polymer solutions used for membrane applications

Rotational and oscillatory shear rheometry were used to quantify the flow behavior under minimal and significant solvent evaporation conditions for polymer solutions used to fabricate isoporous asymmetric membranes by the self-assembly and non-solvent induced phase separation (SNIPS) method. Three different A-B-C triblock terpolymer chemistries of similar molar mass were evaluated: polyisoprene-b-polystyrene-b-poly(4-vinylpyridine) (ISV); polyisoprene-b-polystyrene-b-poly(N,N-dimethylacrylamide) (ISD); and polyisoprene-b-polystyrene-b-poly(tert-butyl methacrylate) (ISB). Solvent evaporation resulted in the formation of a viscoelastic film typical of asymmetric membranes. Solution viscosity and film viscoelasticity were strongly dependent on the chemical structure of the triblock terpolymer molecules. A hierarchical magnitude (ISV > ISB > ISD) was observed for both properties, with ISV solutions displaying the greatest solution viscosity, fastest film strength development, and greatest strength magnitude. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47038.     

Designing block copolymer architectures for targeted membrane performance

Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume fractions but varying in total molar mass from 43 kg/mol to 115 kg/mol to systematically study the effect of polymer size on membrane structure. Small-angle X-ray scattering was used to probe terpolymer solution structure in the dope. All four triblocks displayed solution scattering patterns consistent with a body-centered cubic morphology. After membrane formation, structures were characterized using a combination of scanning electron microscopy and filtration performance tests. Membrane pore densities that ranged from 4.53 × 10¹⁴ to 1.48 × 10¹⁵ pores/m² were observed, which are the highest pore densities yet reported for membranes using self-assembly and non-solvent induced phase separation. Hydraulic permeabilities ranging from 24 to 850 L m⁻² h⁻¹ bar⁻¹ and pore diameters ranging from 7 to 36 nm were determined from permeation and rejection experiments. Both the hydraulic permeability and pore size increased with increasing molar mass of the parent terpolymer. The combination of polymer characterization and membrane transport tests described here demonstrates the ability to rationally design macromolecular structures to target specific performance characteristics in block copolymer derived ultrafiltration membranes.     

Factors Affecting the Study of Chemistry in Different Countries Around the World: Findings from an International Survey

Improving teaching and student learning in chemistry classrooms is an important goal that is constantly researched. Several comparative studies of science teaching have been carried out on different parameters, e. g. misconceptions which science teachers and students may have regarding the scientific concepts they learn and teach. Here we describe science teaching in general, and chemistry teaching in particular, in 12 countries including Israel. Different parameters are compared, including the hours that are devoted to science, the subjects included, the pedagogy, and teachers′ salaries. The survey covers all school levels: elementary school, secondary school and high school. At the high‐school level, the comparison focused on chemistry studies. In this study the variances variables, such as the hours that are allocated for science teaching, did not show an appreciable effect on students′ achievements. It was also found that, in countries where chemistry studies at the high‐school level are not mandatory, innovative pedagogies are more likely to replace the traditional chemistry teaching methods where chemistry is taught according to the structure of the subject based on basic concepts that underlie the curriculum. The study provided an additional support to the importance of the professional development of science and chemistry teachers and suggest that the autonomy that is given to them could influence the quality of science teaching and students′ achievements.