In situ 13C NMR measurements on samples prepared using a pulse-quench catalytic reactor show that the 1,3-dimethylcyclopentenyl carbenium ion (1) is an intermediate in the synthesis of toluene from ...ethylene on zeolite catalyst HZSM-5. Cation 1 forms in less than 0.5 s when ethylene is pulsed onto the catalyst bed at 623 K, and its presence obviates the kinetic induction period for conversion of a subsequent pulse of dimethyl ether, or methanol, into olefins (MTO chemistry). The kinetic induction period returns when the interval between pulses is many times the half-life of 1 in the catalyst bed. Density functional theory calculations (B3LYP/ 6-311G**) on a cluster model of the zeolite confirm that 1 is stable in the zeolite as a free cation and suggest why the alternative framework alkoxy is not observed. A π complex of the neutral cyclic diene is only 2.2 kcal/mol higher in energy than that of the ion pair. Theoretical (GIAO-MP2/tzp) 13C isotropic shifts of isolated 1 are in good agreement with the experimental spectra of the cation in the zeolite. To understand how organic species entrained in the catalyst could promote MTO chemistry, we calculated a number of methylation reactions in the gas phase. We found that the diene formed by deprotonation of 1 is far more easily methylated than ethylene, propene, or toluene. The aggregate experimental and theoretical results reveal the essential features of a mechanism for MTO and methanol to gasoline (MTG) chemistry on a working catalyst.
Proteome analysis by 2‐DE and PMF by MALDI‐TOF MS was performed on human amnion and amniotic fluid at term. Ninety‐two soluble and nineteen membrane proteins were identified from amnion. Thirty‐five ...proteins were identified from amniotic fluid. Calgranulin A and B were found in all patients infected with Ureaplasma urealyticum, but not in any of the patients without infection, indicating that they are potential markers of intrauterine infection. Identity of calgranulin A and B was confirmed by MALDI‐TOF/TOF MS. This study represents the first extensive analysis of the human amnion and amniotic fluid proteome at term and demonstrates that 2‐DE and MALDI‐TOF MS is a useful tool for identifying clinically significant biomarkers of problematic pregnancies.
We have searched for correlations between the pointing directions of ultrahigh energy cosmic rays observed by the High Resolution Fly’s Eye experiment and active galactic nuclei (AGN) visible from ...its northern hemisphere location. No correlations, other than random correlations, have been found. We report our results using search parameters prescribed by the Pierre Auger collaboration. Using these parameters, the Auger collaboration concludes that a positive correlation exists for sources visible to their southern hemisphere location. We also describe results using two methods for determining the chance probability of correlations: one in which a hypothesis is formed from scanning one half of the data and tested on the second half, and another which involves a scan over the entire data set. The most significant correlation found occurred with a chance probability of 24%.
Several recent papers have demonstrated that the conversion of methanol to olefins on the silico-aluminophosphate solid acid catalyst HSAPO-34 usually requires methylbenzenes that function as ...scaffolds (reaction centers) for carbon−carbon bond making and breaking steps. These benzene rings form in the ca. 1 nm cages through ship-in-a-bottle routes from olefins, and they cannot exit the ca. 0.38 nm windows connecting cages. Here, we report a procedure for the selective (80%) synthesis of naphthalene in the cages of HSAPO-34 based on methanol conversion at 600 °C. These naphthalene molecules are accessible to methanol and react at 400 °C to form methylnaphthalenes in the cages with up to four methyl groups. We find that HSAPO-34 catalysts with methylnaphthalenes as the primary entrained hydrocarbon species eliminate ethylene and propene, much like methylbenzenes. A careful comparison of catalysts prepared with either methylnaphthalenes or methylbenzenes showed the former to be ca. one-third as active as the latter (for comparable numbers of reaction centers), but the methylnaphthalene-based catalysts yielded higher ethylene selectivity (at comparable conversions) than the methylbenzene-based catalysts.
The objectives of this study were to explore the mechanisms of metformin sensitization to hypoxia-induced gefitinib treatment in resistant head and neck squamous cell carcinoma (HNSCC) and evaluate ...the effects of this combined treatment strategy.
The effects of gefitinib treatment on HNSCC were measured under normoxic and hypoxic conditions. The relationship between hypoxia and cell cycle and epithelial-mesenchymal transition (EMT) in tumor cells were analyzed. Palbociclib and LY294002 were used in combination with gefitinib to evaluate the effects on HNSCC cell cytotoxicity during hypoxia. Finally, metformin was used to evaluate the sensitizing effects of gefitinib treatment on HNSCC in vivo and in vitro.
Cell viability and apoptosis assays demonstrated a significant difference in HNSCC cells treated with gefitinib between the normoxia and hypoxia groups. Hypoxia induced the expression of cyclin D1, decreased the percentage of cells in G1, and promoted the EMT of tumor cells. Both palbociclib and LY294002 enhanced gefitinib-induced cytotoxicity of HNSCC cells under hypoxic conditions. Encouragingly, metformin sensitized HNSCC to gefitinib treatment in vivo and in vitro.
Hypoxia promotes G1-S cell cycle progression and EMT in HNSCC, resulting in gefitinib treatment resistance. Metformin sensitizes HNSCC to gefitinib treatment, which might serve as a novel combined treatment strategy.
Accurate surveying and mapping data has the characteristics as follows: huge amounts of data, multiform of source and complexity of types. Traditional way of data storing and coping with hard disks ...cannot satisfy the requirements of rapid growth and safe storage of data in surveying and mapping departments. This paper conducted research on the storage and management of surveying and mapping data based on cloud storage. Massive multi-source surveying and mapping data is stored in a distributed storage system named cStor 1, attribute of the data is stored in MySQL database and the spatial index information is stored with the type of Geometry, thus satisfying the requirement of efficient storage of surveying and mapping data, and also making full use of advantages in attribute querying and spatial index building of MySQL. Based on those above, this paper proposed a method for online extraction of spatial index information of multi-source surveying and mapping data based on cloud storage. For different types of surveying and mapping data, there are different policies for extracting spatial index information. Types are divided as follows: For national standard primary scale files and local scale files, spatial index information can be extracted according to the filename. For aerial images and satellite images, the metadata files which are needed can be obtained online and then spatial index information is extracted. The result showed that method proposed in this paper can extract spatial index information efficiently for multi-source surveying and mapping data and the validity of this method was verified.
PDF
