Modifying SBA-15 with Binary Elements of Chromium and Molybdenum for Improved Catalytic Performance in the Oxidative Dehydrogenation of Isobutane to Isobutene

In the oxidative dehydrogenation of isobutane to isobutene, selectivity and stability were improved by introducing chromium and molybdenum into SBA-15. The direct synthesis method (DM) was used to introduce these binary elements into SBA-15. Use of the DM resulted in a higher specific surface area of the catalyst and a greater dispersion of chromium and molybdenum species compared with a corresponding binary catalyst prepared using the incipient wetness impregnation method (IM). Selectivity to isobutene was improved, along with a decrease in the selectivities to CO and CO2 with the introduction of greater amounts of molybdenum, which suggests that molybdenum must suppress the tendency of isobutene to over-oxidate to either CO or CO2. The molybdenum species must be in close proximity to the chromium species, which results in the formation of an active Cr-O-Mo site

A Young Man with Anti-NMDAR Encephalitis following Guillain-Barré Syndrome

A 19-year-old man developed rapidly progressive muscle weakness and dysesthesia in the extremities, and dyspnea after a flu-like episode. Nerve conduction studies showed reduced motor nerve conduction velocities with conduction block, and sensory nerve action potentials could not be evoked. The patient was diagnosed as having Guillain-Barré syndrome (GBS), and was treated with 2 cycles of intravenous immunoglobulin (IVIg) therapy and was assisted by mechanical ventilation. During the recovery course of the illness, he experienced several attacks of psychomotor agitation from the 37th hospital day, and generalized tonic convulsive seizures suddenly developed on the 42nd hospital day. Brain MRI showed high-intensity lesions in the bilateral thalamus and medial temporal lobes. The convulsions were controlled by continuous thiopental infusion (until the 50th hospital day) and mechanical ventilation (until the 84th hospital day). Intravenous methylprednisolone pulse therapy (1,000 mg/day) for 3 days followed by dexamethasone (16 mg/day) was added. After relief of convulsive seizures, prominent orolingual dyskinesia appeared, and on MRI marked atrophy of the bilateral medial temporal lobes was seen. Anti-N-methyl-D-aspartate receptor (NMDAR) antibodies in serum and cerebrospinal fluid were positive on the 92nd hospital day. Anti-NMDAR encephalitis usually affects young females but a small number of male cases with this disease have been reported. Our male patient was unique in having GBS, a post-infectious autoimmune disease, as a preceding disease, suggesting that anti-NMDAR encephalitis itself is caused by a parainfectious autoimmune mechanism

Effect of Introduction of Trace Amount of Chromium Species in Improving Catalytic Performance of MCM-48 in Oxidative Dehydrogenation of Isobutane

The catalytic performance of MCM-48 was greatly improved by the introduction of a small amount of chromium during the oxidative dehydrogenation of isobutane. Various characterization procedures such as XRD, N2 adsorption–desorption isotherms, TEM, NH3-TPD, XPS, and XAFS were used to identify the role that chromium played in the improvement, and XPS and XAFS results provided the most valuable information. Both measurements revealed that the chromium species existed as Cr6+ inside the framework of MCM-48 before oxidative dehydrogenation, but was reduced to Cr3+ during the reaction. The characteristic pore nature of MCM-48 also contributed to an enhancement of the selectivity to isobutene via the suppression of consecutive oxidation reactions

Effects of acidic-basic properties on catalytic activity for the oxidative dehydrogenation of isobutane on calcium phosphates, doped and undoped with chromium

Catalytic activities of calcium hydroxyapatite (HAp) and β-type tricalcium phosphate (β-TCP) were examined for use in the oxidative dehydrogenation (ODH) of isobutane. β-TCP was catalytically inactive for the ODH of isobutane, but stoichiometric HAp afforded a high isobutene yield (5.6%). The isobutane conversion and isobutene selectivity of HAp depended on the atomic ratio of Ca/P. HAp with Ca/P = 1.67 showed the highest isobutene selectivity and isobutene yield among the HAp catalysts with different Ca/P ratios. The characterization of the acidic-basic properties showed that these properties affect the catalytic performance of HAp, and that its basicity is necessary for high catalytic activity. To improve the catalytic activities of calcium phosphates, they were impregnated with Cr. Despite a much lower surface area for β-TCP, Cr-impregnated β-TCP showed a higher isobutene yield (up to 8.4%) than that of Cr-impregnated HAp. The results of the XPS measurement showed that the Cr3+ species on calcium phosphates, owing to basicity, worked as active sites in the ODH of isobutane

Acidic Properties of Various Silica Catalysts Doped with Chromium for the Oxidative Dehydrogenation of Isobutane to Isobutene

Although previous researchers have found that FSM-16 (#16 Folded Sheet Mesoporous material) doped with chromium and related Cr-doped silica catalysts has shown great activity for the oxidative dehydrogenation of isobutane to isobutene, information on the nature of these catalysts is insufficient. For this study, three types of Cr-doped silica catalysts were prepared by applying the template ion exchange method. CrOx/FSM-16 and CrOx/SiO2 were used as references. These catalysts were used for oxidative dehydrogenation, which was then characterized via various techniques. The most active catalyst was Cr-doped silica, which did not have the hexagonal structure that is characteristic of mesoporous FSM-16. Various characterizations showed that the catalytic activity of the Cr-species, stemmed from a weak acidic nature and a redox nature that originated from the combination of silicate and a Cr cation, as opposed to the hexagonal structure and strong acidic nature of FSM-16

Clinical Utility of Germline Genetic Testing in Japanese Men Undergoing Prostate Biopsy

Background: Multiple common variants and also rare variants in monogenic risk genes such as BRCA2 and HOXB13 have been reported to be associated with risk of prostate cancer (PCa); however, the clinical setting in which germline genetic testing could be used for PCa diagnosis remains obscure. Herein, we tested the clinical utility of a 16 common variant-based polygenic risk score (PRS) that has been developed previously for Japanese men and also evaluated the frequency of PCa-associated rare variants in a prospective cohort of Japanese men undergoing prostate biopsy. Methods: A total of 1336 patients undergoing first prostate biopsy were included. PRS was calculated based on the genotype of 16 common variants, and sequencing of 8 prostate cancer-associated genes was performed by multiplex polymerase chain reaction based target sequencing. PRS was combined with clinical factors in logistic regression models to assess whether addition of PRS improves the prediction of biopsy positivity. Results: The top PRS decile was associated with an odds ratio of 4.10 (95% confidence interval = 2.46 to 6.86) with reference to the patients at average risk, and the estimated lifetime absolute risk approached 20%. Among the patients with prostate specific antigen 2-10 ng/mL who had prebiopsy magnetic resonance imaging, high PRS had an equivalent impact on biopsy positivity as a positive magnetic resonance imaging finding. Rare variants were detected in 19 (2.37%) and 7 (1.31%) patients with positive and negative biopsies, respectively, with BRCA2 variants being the most prevalent. There was no association between PRS and high-risk rare variants. Conclusions: Germline genetic testing could be clinically useful in both pre- and post-PSA screening settings