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171.
An intramolecular version of the Yamamoto vinylogous aldol reaction, a method that employs the bulky Lewis acid ATPH to control the site of aldolization, is described. This macrocyclization process is effective for the construction of 10-, 12-, and 14-membered macrolides. The yields are high (70-90%), and the reaction can proceed with excellent remote stereocontrol (dr > or = 20:1) with chiral substrates. 相似文献
172.
173.
The radiation annealing of a rapidly solidified Sn–6.7Sb–5.3Zn (in atomic percent) melt-spun alloy was caused by low-dose gamma ray irradiation. This is observed from the increase in both the volume of unit cell and particle size of the Sn matrix, as revealed from X-ray diffraction analysis, and the decrease in the resistivity. The alloy was irradiated by gamma ray at doses 5, 10, 20, 40, 50, 60, 70, 80, and 100 Gy. The electrical resistivity was measured for the alloys subjected to these doses and it was found that the resistivity decreased by increasing the dose to a minimum value of 50 Gy and then increased by increasing the dose. 相似文献
174.
Amri I Lamia H Gargouri S Hanana M Mahfoudhia M Fezzani T Ezzeddine F Jamoussi B 《Natural product communications》2011,6(10):1531-1536
Essential oils isolated from needles of Pinus patula by hydrodistillation were analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography mass spectrometry (GC-MS). Thirty-eight compounds were identified, representing 98.3% of the total oil. The oil was rich in monoterpene hydrocarbons (62.4%), particularly alpha-pinene (35.2%) and beta-phellandrene (19.5%). The in vitro antifungal assay showed that P. patula oil significantly inhibited the growth of 9 plant pathogenic fungi. The oil, when tested on Sinapis arvensis, Lolium rigidum, Phalaris canariensis and Trifolium campestre, completely inhibited seed germination and seedling growth of all species. Our preliminary results showed that P. patula essential oil could be valorized for the control of weeds and fungal plant diseases. 相似文献
175.
Synthesis of potent and orally efficacious 11β-hydroxysteroid dehydrogenase type 1 inhibitor HSD-016
Wan ZK Chenail E Li HQ Kendall C Wang Y Gingras S Xiang J Massefski WW Mansour TS Saiah E 《The Journal of organic chemistry》2011,76(17):7048-7055
Cortisol and the glucocorticoid receptor (GR) signaling pathway has been linked to the development of diabetes and metabolic syndrome. In vivo, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the conversion of inactive cortisone to its active form, cortisol. Existing clinical data have supported 11β-HSD1 as a valid therapeutic target for type 2 diabetes. In our research program, (R)-1,1,1-trifluoro-2-(3-((R)-4-(4-fluoro-2-(trifluoromethyl)phenyl)-2-methylpiperazin-1-ylsulfonyl)phenyl)propan-2-ol (HSD-016) was discovered to be a potent, selective, and efficacious 11β-HSD1 inhibitor and advanced as a clinical candidate. Herein, a reliable and scalable synthesis of HSD-016 is described. Key transformations include an asymmetric synthesis of a chiral tertiary alcohol via Sharpless dihydroxylation, epoxide formation, and subsequent mild reduction. This route ensured multikilogram quantities of HSD-016 necessary for clinical studies. 相似文献
176.
177.
Choi S Jamshidi A Seok TJ Wu MC Zohdi TI Pisano AP 《Langmuir : the ACS journal of surfaces and colloids》2012,28(6):3102-3111
We report a fast, high-throughput method to create size-tunable micro/nanoparticle clusters via evaporative assembly in picoliter-scale droplets of particle suspension. Mediated by gravity force and surface tension force of a contacting surface, picoliter-scale droplets of the suspension are generated from a nanofabricated printing head. Rapid evaporative self-assembly of the particles on a hydrophobic surface leads to fast clustering of micro/nanoparticles and forms particle clusters of tunable sizes and controlled spacing. The evaporating behavior of the droplet is observed in real-time, and the clustering characteristics of the particles are understood based on the physics of evaporative-assembly. With this method, multiplex printing of various particle clusters with accurate positioning and alignment are demonstrated. Also, size-unifomity of the cluster arrays is thoroughly analyzed by examining the metallic nanoparticle cluster-arrays based on surface-enhanced Raman spectroscopy (SERS). 相似文献
178.
Hanieh Kargarzadeh Ishak Ahmad Ibrahim Abdullah Alain Dufresne Siti Yasmine Zainudin Rasha M. Sheltami 《Cellulose (London, England)》2012,19(3):855-866
Cellulose nanocrystals (CNC) were first isolated from kenaf bast fibers and then characterized. The raw fibers were subjected
to alkali treatment and bleaching treatment and subsequent hydrolysis with sulfuric acid. The influence of the reaction time
on the morphology, crystallinity, and thermal stability of CNC was investigated. Fourier transform infrared spectroscopy showed
that lignin and hemicellulose were almost entirely removed during the alkali and bleaching treatments. The morphology and
dimensions of the fibers and acid-released CNC were characterized by field emission scanning electron microscopy and transmission
electron microscopy. X-Ray diffraction analysis revealed that the crystallinity first increases upon hydrolysis and then decreases
after long durations of hydrolysis. The optimal extraction time was found to be around 40 min during hydrolysis at 45 °C with
65% sulfuric acid. The thermal stability was found to decrease as the hydrolysis time increased. The electrophoretic mobility
of the CNC suspensions was measured using the zeta potential, and it ranged from −8.7 to −95.3 mV. 相似文献
179.
H Kisserwan A Kamar T Shoker TH Ghaddar 《Dalton transactions (Cambridge, England : 2003)》2012,41(35):10643-10651
A new class of cyclometalated ruthenium complexes, Ru(C^N^N')(N^N'^N')·Cl where N^N'^N' = 4,4',4'-tricarboxy-2,2':6',2'-terpyridine and C^N^N' = substituted 6-phenyl-2,2'-bipyridine, for Dye Sensitized Solar Cells (DSSCs) is proposed. We have investigated the effect of different substituents (R = COOH, thiophen-2-yl, F and OCH(3)) on the ancillary C^N^N' ligand on the photophysical properties and performance of the six different cyclometalated ruthenium complexes in DSSCs. Using an ionic liquid based electrolyte, efficiencies up to η = 3.06% have been attained under 1 sun irradiation. Moreover, the T66 based DSSC exhibited a good stability under 1000 W m(2) light soaking at 60 °C for 24 days, retaining 92.8% of its initial efficiency. 相似文献
180.
Daga P Winston G Modat M White M Mancini L Cardoso MJ Symms M Stretton J McEvoy AW Thornton J Micallef C Yousry T Hawkes DJ Duncan JS Ourselin S 《IEEE transactions on medical imaging》2012,31(4):882-891
Accurate localization of the optic radiation is key to improving the surgical outcome for patients undergoing anterior temporal lobe resection for the treatment of refractory focal epilepsy. Current commercial interventional magnetic resonance imaging (MRI) scanners are capable of performing anatomical and diffusion weighted imaging and are used for guidance during various neurosurgical procedures. We present an interventional imaging workflow that can accurately localize the optic radiation during surgery. The workflow is driven by a near real-time multichannel nonrigid image registration algorithm that uses both anatomical and fractional anisotropy pre- and intra-operative images. The proposed workflow is implemented on graphical processing units and we perform a warping of the pre-operatively parcellated optic radiation to the intra-operative space in under 3 min making the proposed algorithm suitable for use under the stringent time constraints of neurosurgical procedures. The method was validated using both a numerical phantom and clinical data using pre- and post-operative images from patients who had undergone surgery for treatment of refractory focal epilepsy and shows strong correlation between the observed post-operative visual field deficit and the predicted damage to the optic radiation. We also validate the algorithm using interventional MRI datasets from a small cohort of patients. This work could be of significant utility in image guided interventions and facilitate effective surgical treatments. 相似文献