Optimized Synthesis and Structural Characterization of the Borosilicate MCM-70

A structure analysis of the borosilicate zeolite MCM-70, whose synthesis had been patented in 2003, was reported in 2005. Unfortunately, that structure analysis was somewhat ambiguous. Anisotropic line broadening made it difficult to model the peak shape, some peaks in the electron density map could not be interpreted satisfactorily, the framework geometry was distorted, and MAS NMR results were partially contradictory. In an attempt to resolve some of these points, an optimization of the synthesis was undertaken, and the structure was reinvestigated. The structure was solved from synchrotron powder diffraction data collected on an as-synthesized sample (Pmn2_1, a = 13.3167(1) Å, b = 4.6604(1) Å, c = 8.7000(1) Å) using a powder charge-flipping algorithm. The framework topology, with a 1-dimensional, 10-ring channel system, is identical to the one previously reported. However, the B in this new sample was found to be ordered in the framework, fully occupying one of the four tetrahedral sites. Two extra-framework K^+ ion positions, each coordinated to five framework O atoms and one water molecule, were also found. The solid state ^(29)Si, ^(11)B and ^1H NMR results are fully consistent with this ordered structure

Density of mechanisms within the flexibility window of zeolites

By treating idealized zeolite frameworks as periodic mechanical trusses, we show that the number of flexible folding mechanisms in zeolite frameworks is strongly peaked at the minimum density end of their flexibility window. 25 of the 197 known zeolite frameworks exhibit an extensive flexibility, where the number of unique mechanisms increases linearly with the volume when long wavelength mechanisms are included. Extensively flexible frameworks therefore have a maximum in configurational entropy, as large crystals, at their lowest density. Most real zeolites do not exhibit extensive flexibility, suggesting that surface and edge mechanisms are important, likely during the nucleation and growth stage. The prevalence of flexibility in real zeolites suggests that, in addition to low framework energy, it is an important criterion when searching large databases of hypothetical zeolites for potentially useful realizable structures.Comment: 11 pages, 3 figure

Synthesis and structure of polymorph B of zeolite Beta

[EN] It was found that either polymorph B or polymorph C of zeolite beta can be obtained from the same structure directing agent: 4,4-dimethyl-4-azonia-tricyclo[5.2.2.0(2,6)] undec-8-ene hydroxide. The synthesis occurs through a consecutive process where polymorph B is first formed and then transformed into polymorph C. It is possible to produce a zeolite highly enriched in polymorph B, provided that the transformation of this phase into polymorph C is slowed down up to the point where polymorph C is only detected at trace levels. The structure of polymorph B was determined for the first time by electron crystallography with SAED and HRTEM from areas of unfaulted polymorph B crystals.Financial support from the Spanish Government (Project MAT2006-14274-C02–01) and the EU Commission (TOPCOMBI Project) is gratefully acknowledged. M.M. thanks CSIC for an I3P grant. J.S. is supported by a postdoctoral grant from the Carl Trygger Foundation. The Berzelii Centre EXSELENT is supported by the Swedish Research Council (VR) and the Swedish Governmental Agency for Innovation Systems (VINNOVA).Corma Canós, A.; Moliner Marin, M.; Cantin Sanz, A.; Díaz Cabañas, MJ.; Jorda Moret, JL.; Zhang, D.; Sun, J.... (2008). Synthesis and structure of polymorph B of zeolite Beta. Chemistry of Materials. 20(9):3218-3223. doi:10.1021/cm8002244S3218322320

Does the Constitution Provide More Ballot Access Protection for Presidential Elections Than for U.S. House Elections?

Both the U.S. Constitution and The Federalist Papers suggest that voters ought to have more freedom to vote for the candidate of their choice for the U.S. House of Representatives than they do for the President or the U.S. Senate. Yet, strangely, for the last thirty-three years, the U.S. Supreme Court and lower courts have ruled that the Constitution gives voters more freedom to vote for the candidate of their choice in presidential elections than in congressional elections. Also, state legislatures, which have been writing ballot access laws since 1888, have passed laws that make it easier for minor-party and independent candidates to get on the ballot for President than for the U.S. House. As a result, voters in virtually every state invariably have far more choices on their general election ballots for the President than they do for the House. This Article argues that the right of a voter to vote for someone other than a Democrat or a Republican for the House is just as important as a voter’s right to do so for President, and that courts should grant more ballot access protection to minor-party and independent candidates for the House

Complete sequence-based pathway analysis by differential on-chip DNA and RNA extraction from a single cell

Abstract We demonstrate on-chip, differential DNA and RNA extraction from a single cell using a microfluidic chip and a two-stage lysis protocol. This method enables direct use of the whole extract, without additional washing steps, reducing sample loss. Using this method, the tumor driving pathway in individual cells from a colorectal cancer cell line was determined by applying a Bayesian computational pathway model to sequences obtained from the RNA fraction of a single cell and, the mutations driving the pathway were determined by analyzing sequences obtained from the DNA fraction of the same single cell. This combined functional and mutational pathway assessment of a single cell could be of significant value for dissecting cellular heterogeneity in tumors and analyzing single circulating tumor cells

Characterization of the apoptotic response of human leukemia cells to organosulfur compounds

Background: Novel therapeutic agents that selectively induce tumor cell death are urgently needed in the clinical management of cancers. Such agents would constitute effective adjuvant approaches to traditional chemotherapy regimens. Organosulfur compounds (OSCs), such as diallyl disulfide, have demonstrated anti-proliferative effects on cancer cells. We have previously shown that synthesized relatives of dysoxysulfone, a natural OSC derived from the Fijian medicinal plant, Dysoxylum richi, possess tumor-specific antiproliferative effects and are thus promising lead candidates. Methods: Because our structure-activity analyses showed that regions flanking the disulfide bond mediated specificity, we synthesized 18 novel OSCs by structural modification of the most promising dysoxysulfone derivatives. These compounds were tested for anti-proliferative and apoptotic activity in both normal and leukemic cells. Results: Six OSCs exhibited tumor-specific killing, having no effect on normal bone marrow, and are thus candidates for future toxicity studies. We then employed mRNA expression profiling to characterize the mechanisms by which different OSCs induce apoptosis. Using Gene Ontology analysis we show that each OSC altered a unique set of pathways, and that these differences could be partially rationalized from a transcription factor binding site analysis. For example, five compounds altered genes with a large enrichment of p53 binding sites in their promoter regions (p < 0.0001). Conclusions: Taken together, these data establish OSCs derivatized from dysoxysulfone as a novel group of compounds for development as anti-cancer agents

Synthesis of the Ti-Silicate Form of BEC Polymorph of B-Zeolite Assisted by Molecular Modeling

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/jp805400u Published Work, see http://pubs.acs.org/page/policy/articlesonrequest/index.html[EN] The K(+) free pure silica form of polymorph C (BEC) of beta-zeolite has been synthesized with a cationic organic structure directing agent (SDA) that was predicted best, out of a series of nine potentials, by means of modeling techniques. On the bases of this synthesis method, the Ti-BEC zeolite has been obtained which owing to the pore topology and dimensions shows a higher epoxidation activity than the Ti-beta-polymorph either with H(2)O(2) or organic peroxides as oxidants.The authors thank the CICYT for financial support (Project MAT 2006-14274-CO2-01). G.S. thanks "Centro de Calculo de la Universidad Politecnica de Valencia" for the use of their computational facilities. M.M. and P.S. thank ITQ for a scholarship. We also thank intramural project CRENATUM.Moliner Marin, M.; Serna Merino, PM.; Cantin Sanz, A.; Sastre Navarro, GI.; Díaz Cabañas, MJ.; Corma Canós, A. (2008). Synthesis of the Ti-Silicate Form of BEC Polymorph of B-Zeolite Assisted by Molecular Modeling. The Journal of Physical Chemistry C. 112(49):19547-19554. https://doi.org/10.1021/jp805400uS19547195541124

A randomised sham controlled trial of vertebroplasty for painful acute osteoporotic vertebral fractures (VERTOS IV)

<p>Abstract</p> <p>Background</p> <p>The standard care in patients with a painful osteoporotic vertebral compression fracture (VCF) is conservative therapy. Percutaneous vertebroplasty (PV), a minimally invasive technique, is a new treatment option. Recent randomized controlled trials (RCT) provide conflicting results: two sham-controlled studies showed no benefit of PV while an unmasked but controlled RCT (VERTOS II) found effective pain relief at acceptable costs. The objective of this study is to compare pain relief after PV with a sham intervention in selected patients with an acute osteoporotic VCF using the same strict inclusion criteria as in VERTOS II. Secondary outcome measures are back pain related disability and quality of life.</p> <p>Methods</p> <p>The VERTOS IV study is a prospective, multicenter RCT with pain relief as primary endpoint. Patients with a painful osteoporotic VCF with bone edema on MR imaging, local back pain for 6 weeks or less, osteopenia and aged 50 years or older, after obtaining informed consent, are included and randomized for PV or a sham intervention. In total 180 patients will be enrolled. Follow-up is at regular intervals during a 1-year period with a standard Visual Analogue Scale (VAS) score for pain and pain medication. Necessary additional therapies and complications are recorded.</p> <p>Discussion</p> <p>The VERTOS IV study is a methodologically sound RCT designed to assess pain relief after PV compared to a sham intervention in patients with an acute osteoporotic VCF selected on strict inclusion criteria.</p> <p>Trial registration</p> <p>This study is registered at ClinicalTrials.gov., <a href="http://www.clinicaltrials.gov/ct2/show/NCT01200277">NCT01200277</a>.</p