Charge distribution and conformational stability effects of organic structure-directing agents on zeolite synthesis

While the use of the so-called organic structure-directing agents (OSDAs) is no stranger to zeolite synthesis at all, the effects of their charge distribution and conformational stability on the phase selectivity of the crystallization remain elusive. To systematically investigate these effects, we have prepared a series of imidazolium and pyrazolium derivatives with the same geometric shape but different positions of nitrogen atoms in the five-membered heterocyclic aromatic ring and used them as OSDAs for the synthesis of zeolites with pure-silica composition. Meaningful differences in the zeolite product were observed.11Ysciescopu

Unexpected contraction of a zeolite framework upon isomorphous substitution of Si by Al

Isomorphous substitution of Si by Al in the framework of sodalites synthesized in ethylene glycol causes an unexpected contraction of the zeolite framework

Prostate Cancer Metastasis to the Stomach

Prostate cancer commonly manifests with bony metastases. Visceral metastasis can also occur in the lungs and liver. However, stomach metastasis related to prostate cancer is rare. Here, we report a case of prostate cancer metastatic to the stomach. A 66-year-old male was diagnosed with prostate adenocarcinoma. He was noted as having abdominal discomfort, nausea, and vomiting 18 months after the diagnosis. A histopathologic examination and an esophagogastroduodenoscopic gastric biopsy revealed stomach-metastatic adenocarcinoma. He was also noted as having cerebellar metastatic lesions, which were identified by using a brain magnetic resonance imaging (MRI) scan. The patient died of cardiovascular complications 5 months after the diagnosis of stomach metastasis

Targeted synthesis of two super-complex zeolites with embedded isoreticular structures

A novel structural coding approach combining structure solution, prediction, and the targeted synthesis of new zeolites with expanding complexity and embedded isoreticular structures was recently proposed. Using this approach, the structures of two new zeolites in the RHO family, PST-20 and PST-25, were predicted and synthesized. Herein, by extending this approach, the next two higher generation members of this family, PST-26 and PST-28, have been predicted and synthesized. These two zeolites have much larger unit cell volumes (422 655 Å3 and 614 912 Å3, respectively) than those of the lower generations. Their crystallization was confirmed by a combination of both powder X-ray and electron diffraction techniques. Aluminate and water concentrations in the synthetic mixture were found to be the two most critical factors influencing the structural expansion of embedded isoreticular zeolites under the synthetic conditions studied herein.PostprintPostprintPeer reviewe

Light-chain amyloidosis presenting with rapidly progressive submucosal hemorrhage of the stomach

SummaryThe gastrointestinal tract is frequently in involved light-chain (AL) amyloidosis, but significant hemorrhagic complications are rare. A 71-year-old man presented to our hospital with dyspepsia and heartburn for 1 month. Gastroscopy revealed a large submucosal hematoma at the gastric fundus. Two days later, a follow-up gastroscopy indicated extensive expansion of the hematoma throughout the upper half of the stomach. The hematoma displayed ongoing expansion during the endoscopic examination, suggesting that rupture was imminent. Emergency total gastrectomy was performed, and amyloidosis was confirmed after examining the surgical specimen. Bone marrow examination revealed multiple myeloma, and serum immunoglobulin assay confirmed the diagnosis of myeloma-associated AL amyloidosis. At manuscript submission, the patient was doing well and was undergoing chemotherapy

Understanding CO2 adsorption in a flexible zeolite through a combination of structural, kinetic and modelling techniques

In this study we show how non-trivial equilibrium and kinetic adsorption behaviour in a flexible zeolite can be understood through a combination of experimental characterisation and modelling. Flexible zeolites, such as those in the RHO-family, can exhibit unusual stepped isotherms in the presence of CO2, but their structural complexity makes it hard to attribute a clear mechanism. Here we present a structural and kinetic study on (Na,TEA)-ZSM-25, an extended member of the RHO-family, and show that by combining diffraction data, lattice fluid modelling and dynamic column experiments, we obtain a plausible mechanism for CO2 adsorption and transport in this material. It is evident that by using any single technique, the behaviour is too complex to be readily understood. This is to our knowledge the first study to measure and model the changing kinetics due to adsorption induced framework flexibility.11Nsciescopu

The Occurrence and Speed of CMEs Related to Two Characteristic Evolution Patterns of Helicity Injection in Their Solar Source Regions

Long-term (a few days) variation of magnetic helicity injection was calculated for 28 solar active regions which produced 47 CMEs to find its relationships with the CME occurrence and speed using SOHO/MDI line-of-sight magnetograms. As a result, we found that the 47 CMEs can be categorized into two different groups by two characteristic evolution patterns of helicity injection in their source active regions which appeared for about 0.5-4.5 days before their occurrence: (1) a monotonically increasing pattern with one sign of helicity (Group A; 30 CMEs in 23 active regions) and (2) a pattern of significant helicity injection followed by its sign reversal (Group B; 17 CMEs in 5 active regions). We also found that CME speed has a correlation with average helicity injection rate with linear correlation coefficients of 0.85 and 0.63 for Group A and Group B, respectively. In addition, these two CME groups show different characteristics as follows: (1) the average CME speed of Group B (1330km/s) is much faster than that of Group A (870km/s), (2) the CMEs in Group A tend to be single events, whereas those in Group B mainly consist of successive events, and (3) flares related to the CMEs in Group B are relatively more energetic and impulsive than those in Group A. Our findings therefore suggest that the two CME groups have different pre-CME conditions in their source active regions and different CME characteristics.Comment: 25 pages, 7 figures, accepted for publication in Ap

Measuring abutment convergence angles using stereovision dental image processing system

PURPOSE. The purpose of this study was to develop a dental image processing system using a three-dimensional (3D) camera and stereovision technology. The reliability of the system for measuring axial wall convergence angles was evaluated. MATERIALS AND METHODS. The new system predicted 3D coordinate points from 2D images and calculated distances and angles between points. Two examiners measured axial wall convergence angles for seven artificial abutments using a traditional tracing-based method (TBM) and the stereovision-based method (SVBM). Five wax abutment models of simplified abutment forms were made and axial wall convergence angles of wax models were measured by both methods. The data were statistically analyzed at the level of significance, 0.05. RESULTS. Intraclass correlation coefficients showed excellent intra-examiner and inter-examiner reliabilities for both methods. Bland-Altman plots and paired t-tests showed significant differences between measurements and true values using TBM; differences were not significant with SVBM. CONCLUSION. This study found that the SVBM reflected true angle values more accurately than a TMB and illustrated an example of 3D computer science applied to clinical dentistry.OAIID:oai:osos.snu.ac.kr:snu2014-01/102/2008003883/6SEQ:6PERF_CD:SNU2014-01EVAL_ITEM_CD:102USER_ID:2008003883ADJUST_YN:YEMP_ID:A078517DEPT_CD:861CITE_RATE:.631DEPT_NM:치의학과SCOPUS_YN:YCONFIRM: