Mesoporous MCM-41 materials with a distinct N 2 -sorption hysteresis behavior have been prepared from pure silica and aluminosilicate-C 16 trimethylammonium (TMA)Br systems by a delayed neutralization procedure. On the basis of the analysis of transmission electron microscopy micrographs of these MCM-41 materials, we observed that the sample with large type-H4 hysteresis loop at p/p 0 between 0.5 and 1.0 contains extensive structural defect holes amid the nanochannels. These holes are irregular in shape and their size distributes between 5.0 and 30.0 nm. The pore-blocking effect leads to the hysteresis in desorption. Aluminosilicate MCM-41 often possesses a larger hysteresis loop than pure silica MCM-41. The linear channel system of MCM-41 becomes effectively interconnected through these defect holes. The unusual adsorption hysteresis is associated with the pore-blocking effect around the embedded voids in the framework structures. The size of the adsorption-desorption hysteresis loop is proportional to the volume of hole defects in the nanochannels, and it is dependent on the synthesis conditions such as water content, Si/Al ratio, and morphology. Tubular morphology is often associated with large hysteresis behavior and thus more hole defects. The interconnecting channels through defect holes thus makes the diffusion of molecules inside the MCM-41 structure more effective, which is important in catalysis applications.
Hollow silica spheres with mesostructured shells (HSSMS) were prepared with a vesicle template of cetyltrimethylammonium bromide-sodium dodecyl sulfate-Pluronic P123 (C(16)TMAB-SDS-EO(20)PO(70)EO(20)) at a SDS/C(16)TMAB ratio of 0.6-0.8 following a fast silicification in dilute silicate solution at pH approximately 5.0. The mesostructure of the shell is disordered, and the mesopore size is about 5.5-7.5 nm. Moreover, the direction and length of the nanochannels of the shell change with the SDS/C(16)TMAB ratios. A bi-template model, in which the C(16)TMA(+)-DS(-) form the stable bilayer vesicle structure and the P123 copolymers anchored on C(16)TMA(+)-DS(-) vesicle act as the template for the mesoporous silica, was proposed to explain the formation of the HSSMS. This bi-template model can be applied extensively to prepare the HSSMS with different diameters and pore sizes by using other C(n)TMAX-SDS-EO(n)PO(m))EO(n) ternary-surfactant mixtures.
A facile synthesis route for preparing SBA-15 silica of platelet shape and very short mesochannels (150-350 nm) was developed by introducing a small amount of Zr(IV) ions in the synthesis solution.The synthesis route can be easily extended to prepare platelet SBA-15 materials with various organic functional groups up to 1.87 mmol/g loading in one pot. In situ XRD and freeze-fracture replication TEM were found to be powerful techniques for studying the self-assembly processes. The platelet SBA-15 with short mesochannels in 150-350 nm was formed because of the fast self-assembly rate of P123 micelles and TEOS accelerated by the Zr(IV) ions in the synthesis solution. The platelet SBA-15 materials are superior to the conventional SBA-15 of rod or fiber morphologies in facilitating molecular diffusion and less possibility of pore blockage when used in the sorption or reactions of bulky molecules.
Due to multiple beneficial effects, including control of disease activity, reduction in cardiovascular events and improved survival, hydroxychloroquine is now recommended long‐term for all patients with systemic lupus erythematosus. However, patients must be made aware of the possible risk of retinal toxicity and have eye examinations to monitor for this complication. As hydroxychloroquine becomes more widely used in systemic lupus erythematosus, physicians must also be aware of rare but serious adverse effects, including neuromyotoxicity and cardiotoxicity.
This paper introduces a network architecture to solve the structure-from-motion (SfM) problem via feature-metric bundle adjustment (BA), which explicitly enforces multi-view geometry constraints in the form of feature-metric error. The whole pipeline is differentiable, so that the network can learn suitable features that make the BA problem more tractable. Furthermore, this work introduces a novel depth parameterization to recover dense per-pixel depth. The network first generates several basis depth maps according to the input image, and optimizes the final depth as a linear combination of these basis depth maps via feature-metric BA. The basis depth maps generator is also learned via end-to-end training. The whole system nicely combines domain knowledge (i.e. hard-coded multi-view geometry constraints) and deep learning (i.e. feature learning and basis depth maps learning) to address the challenging dense SfM problem. Experiments on large scale real data prove the success of the proposed method.
Primary cell cultures from the lymphoid organ of Penaeus monodon were used to investigate in vitro propagation and morphogenesis of white spot syndrome virus (WSSV). Double-strength Leibovitz's L15 supplemented with 20% fetal bovine serum, pH 7.5, with a final osmolarity of 530 i 5 mOsm kg-' was identified as the most suitable culture medium. In this medium, the lymphoid cells remained viable for more than 1 wk. Migrating cells were inoculated with WSSV, and the consequent cytopathic effects documented by light and electron microscopy. WSSV appears capable of following 2 alternative assembly sequences, one similar to the morphogenesis of the Oryctes rhinocerus virus and another which is more typical of baculoviral assembly. Possible relationships between WSSV, Oryctes virus, and baculoviruses are discussed.
Well-ordered Ti-incorporated SBA-15 materials (shortly termed Ti-SBA-15) with Ti loading up to 10 mol% of Si were prepared by a one pot co-condensation method using tetraethyl orthosilicate (TEOS) as the silica source and titanium oxychloride as the Ti source in an acidic environment close to the isoelectric point of silanol groups (pH ¼ 1.27-2.37). The Ti-SBA-15 materials with Ti/Si ratios smaller than 0.05 were curved solid tubes, while those with the Ti/Si ratios between 0.05-0.1 possessed platelet morphology and short mesochannels (ca. 150-500 nm). Titanium was homogeneously distributed in the silica framework of the as-made Ti-SBA-15 materials as isolated Ti species when the Ti/Si ratios were lower than 0.03. It formed small TiO 2 nanocrystallites when the Ti loading was further increased or after the materials were calcined at temperatures higher than 500 C. It is noteworthy that tetrahedrally coordinated Ti(IV) species were generated on the superficial areas of SBA-15 silica framework upon calcination at 600-1000 C. These tetrahedrally coordinated Ti(IV) species not only stabilized the mesopore ordering up to 950-1000 C, but also acted as effective catalytic sites in cyclohexene epoxidation.
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