Stability of Ca-montmorillonite hydrates: A computer simulation study

Classic simulations are used to study interlayer structure, swelling curves, and stability of Ca-montmorillonite hydrates. For this purpose, NPzzT$ and MuPzzT ensembles are sampled for ground level and given burial conditions. For ground level conditions, a double layer hydrate having 15.0 A of basal spacing is the predominant state for relative vapor pressures (p/po) ranging in 0.6-1.0. A triple hydrate counting on 17.9 A of interlaminar distance was also found stable for p/po=1.0. For low vapor pressures, the system may produce a less hydrated but still double layer state with 13.5 A or even a single layer hydrate with 12.2 A of interlaminar distance. This depends on the established initial conditions. On the other hand, the effect of burial conditions is two sided. It was found that it enhances dehydration for all vapor pressures except for saturation, where swelling is promoted.Comment: 8 pages, 9 figure

Incorporating Knowledge of Students Systematically into TPACK-based Instruction: An Illustration

How might teachers’ knowledge of students’ specific learning needs and preferences be incorporated into their TPACK, and subsequently into their practice? How can this knowledge help teachers to select and employ particular technologies in specific ways that can accommodate students’ differing learning requirements? Building upon previous work that supports teachers’ TPACK-based instructional planning with taxonomies of learning activity types in nine different curriculum areas, we developed a taxonomy of teaching strategies, each supported by recommended digital technologies, that are specific to particular learners’ needs. In this first TPACK-based teaching strategies taxonomy, the needs of English Language Learners (ELLs) are addressed. The new taxonomy is designed to be used in concert with one or more curriculum-based learning activity types taxonomies, scaffolding the development and use of teachers’ TPACK while they are planning curriculum-based, well-differentiated instruction

Nowhere to go: How stigma limits the options of female drug users after release from jail

Background Drug and alcohol using women leaving prison or jail face many challenges to successful re-integration in the community and are severely hampered in their efforts by the stigma of drug or alcohol use compounded by the stigma of incarceration. Methods This qualitative study is based on individual semi-structured interviews and focus groups with 17 women who had recently left jail about the challenges they faced on reentry. Results Our analysis identified three major themes, which are related by the overarching influence of stigma: survival (jobs and housing), access to treatment services, and family and community reintegration. Conclusion Stigma based on drug use and incarceration works to increase the needs of women for health and social services and at the same time, restricts their access to these services. These specific forms of stigma may amplify gender and race-based stigma. Punitive drug and social policies related to employment, housing, education, welfare, and mental health and substance abuse treatment make it extremely difficult for women to succeed

Grounded Technology Integration: Instructional Planning Using Curriculum-Based Activity Type Taxonomies

Technological pedagogical content knowledge (tpck or tpack) – the highly practical professional educational knowledge that enables and supports technology integration – is comprised of teachers’ concurrent and interdependent curriculum content, general pedagogy, and technological understanding. Teachers’ planning – which expresses teachers’ professional knowledge (including tpack) in pragmatic ways -- is situated, contextually sensitive, routinized, and activity-based. To assist with technology integration, therefore, we suggest using what is understood from research about teachers’ knowledge and instructional planning to form an approach to curriculum-based technology integration that is predicated upon teachers combining technologically supported learning activity types selected from content-keyed activity type taxonomies. In this article, we describe this approach to curriculum-based technology integration, illustrating it with overviews of and examples from six curriculum-based learning activity types taxonomies that have been developed to date. We invite our readers to vet and use these materials, which are available on the activity types Wiki (http://activitytypes.wmwikis.net/)

Shear Viscosity of Clay-like Colloids in Computer Simulations and Experiments

Dense suspensions of small strongly interacting particles are complex systems, which are rarely understood on the microscopic level. We investigate properties of dense suspensions and sediments of small spherical Al_2O_3 particles in a shear cell by means of a combined Molecular Dynamics (MD) and Stochastic Rotation Dynamics (SRD) simulation. We study structuring effects and the dependence of the suspension's viscosity on the shear rate and shear thinning for systems of varying salt concentration and pH value. To show the agreement of our results to experimental data, the relation between bulk pH value and surface charge of spherical colloidal particles is modeled by Debye-Hueckel theory in conjunction with a 2pK charge regulation model.Comment: 15 pages, 8 figure

Epigenetic Tailoring for the Production of Anti-Infective Cytosporones from the Marine Fungus Leucostoma persoonii

Recent genomic studies have demonstrated that fungi can possess gene clusters encoding for the production of previously unobserved secondary metabolites. Activation of these attenuated or silenced genes to obtain either improved titers of known compounds or new ones altogether has been a subject of considerable interest. In our efforts to discover new chemotypes that are effective against infectious diseases, including malaria and methicillin-resistant Staphylococcus aureus (MRSA), we have isolated a strain of marine fungus, Leucostoma persoonii, that produces bioactive cytosporones. Epigenetic modifiers employed to activate secondary metabolite genes resulted in enhanced production of known cytosporones B (1, 360%), C (2, 580%) and E (3, 890%), as well as the production of the previously undescribed cytosporone R (4). Cytosporone E was the most bioactive, displaying an IC90 of 13 µM toward Plasmodium falciparum, with A549 cytotoxicity IC90 of 437 µM, representing a 90% inhibition therapeutic index (TI90 = IC90 A459/IC90 P. falciparum) of 33. In addition, cytosporone E was active against MRSA with a minimal inhibitory concentration (MIC) of 72 µM and inhibition of MRSA biofilm at roughly half that value (minimum biofilm eradication counts, MBEC90, was found to be 39 µM)

Noroviruses in Archival Samples

Application of recent techniques to detect current pathogens in archival effluent samples collected and concentrated in 1987 lead to the characterization of norovirus GGII.6 Seacroft, unrecognized until 1990 in a clinical sample. Retrospective studies will likely increase our knowledge about waterborne transmission of emerging pathogens