507,040 research outputs found
Class-C PA-VCO Cell for FSK and GFSK Transmitters
No full textIn this paper, a Class-C PA-VCO cell tailored to FSK/GFSK transmitters is presented. In the proposed solution, a Class-C VCO and a common-gate stage PA are stacked in a current-reuse architecture operating with 1.2 V power supply. The PA and the VCO efficiencies are maximized by adjusting their voltage headroom without the use of any DC-DC converters. The PA-VCO is inserted in a transmitter based on an open-loop architecture. The presented prototype, fabricated in 0.13 μm CMOS technology, occupies an active area of 0.2 mm2. A maximum TX efficiency of 17.5% is achieved while the TX is delivering an output power of -1 dBm at 2.45 GHz. A phase noise of -129 dBc/Hz at 2.5 MHz frequency offset results in a carrier-frequency drift below 7 Hz/s and an FSK error below 0.7%, which allows the transmitter to operate in open-loop while delivering long data-packets. The transmitter is also compliant to BLE specifications when FSK and GFSK modulations with index of 0.5 are applied
MPTP/MPP+ suppresses activation of protein C in Parkinson's disease
No full textEndothelial dysfunction and disruption of the blood-brain barrier have been found to be associated with Parkinson's disease (PD). However, the mechanisms underlying these effects have yet to be elucidated. It has also been found that activated protein C (APC) displays neuroprotective properties. Presently, the effects of APC on PD remain unknown. Using a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) neurotoxin rodent model of PD, we found that administration of MPTP can reduce expression of endothelial protein C receptor (EPCR), an N-glycosylated type I membrane protein that has the ability to enhance protein C activation. However, the use of MPTP does not alter levels of thrombomodulin. These findings were verified in an in vitro study showing that 1-methyl-4-phenylpyridinium (MPP+) treatment leads to suppression of EPCR along with reduction of protein C activation in human primary endothelial cells. Importantly, our results display that activation of the transcriptional factor SP1 is involved in the inhibitory effects of MPTP/MPP+ on EPCR expression. We found that using 300 nM of the SP1 inhibitor MIT can abolish the effects of MPP+ on EPCR expression. Consistently, SP1 silencing using small RNA interference was able to prevent the inhibitory effects of MPTP/MPP+ on the reduction of EPCR expression and impairment of protein C activation. Importantly, our results indicate that overexpression of SP1 inhibits EPCR promoter activity. Our study suggests that EPCR-APC may be a potential therapeutic target for endothelial dysfunction in P
Mesoporous Si and multi-layered Si/C films by Pulsed Laser Deposition as Li-ion microbattery anodes
Get PDFSilicon is a very attractive Li-ion battery anode material due to its high theoretical capacity, but proper nanostructuring is needed to accommodate the large volume expansion/shrinkage upon reversible cycling. Hereby, novel mesoporous Si nanostructures are grown at room temperature by simple and rapid Pulsed Laser Deposition (PLD) directly on top of the Cu current collector surface. The samples are characterised from the structural/morphological viewpoint and their promising electrochemical behaviour demonstrated in lab-scale lithium cells. Depending on the porosity, easily tuneable by PLD, specific capacities approaching 250 μAh cm−2 are obtained. Successively, newly elaborated bicomponent silicon/carbon nanostructures are fabricated in one step by alternating PLD deposition of Si and C, thus resulting in novel multi-layered composite mesoporous films exhibiting profoundly improved performance. Alternated deposition of Si/C layers by PLD is proven to be a straightforward method to produce multi-layered anodes in one processing step. The addition of carbon and mild annealing at 400 °C stabilize the electrochemical performance of the Si based nanostructures in lab-scale lithium cells, allowing to reach very stable prolonged reversible cycling at improved specific capacity values. This opens the way to further reducing processing steps and processing time, which are key aspects when upscaling is sought
Elastic scattering and total reaction cross sections for the (8)Li+(12)C system
No full textThe elastic-scattering angular distribution for (8)Li on (12)C has been measured at E(LAB) = 23.9 MeV with (8)Li radioactive nuclear beam produced by the Radioactive Ion Beams in Brazil facility. This angular distribution was analyzed in terms of optical-model with Woods-Saxon and double-folding Sao Paulo potential. The roles of the breakup and inelastic channels were also investigated with cluster folding and deformed potentials, respectively, through coupled-channels calculations. The angular distribution for the proton-transfer (12)C((8)Li, (9)Be)(11)B reaction was also measured at the same energy. The spectroscopic factor for the <(9)Be|(8)Li + p > bound system was obtained and compared with shell-model calculations and with other experimental values. Total reaction cross sections for the present system were also extracted from the elastic-scattering analysis. A systematic of the reduced reaction cross sections obtained from the present and published data on (6,7,8)Li isotopes on (12)C was performed as a function of energy.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[2003/10099-2]Fundacao de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ)Conselho Nacional de Pesquisa e Desenvolvimento (CNPq)Projeto de acao complementaria internacional Sevilla-Sao Paulo[PCI2006-A7-0654](CAPES) Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior ( APES
Bis(arylimido) molybdenum(VI) amidinate and guanidinate complexes; Molecular structures of [(ArN)(2)MoMe{N(Cy)C[N(i-Pr)(2)]N(Cy)}] (Ar=2,6-i-Pr2C6H3; Cy = cyclohexyl) and [(2,6-i-Pr2C6H3N)(2)MoCl2]center dot[NH=C(C6H5)CH(SiMe3)(2)]
No full textThe reaction of [(ArN)(2)MoCl2]. DME (Ar = 2,6-i-Pr6C6H3) (1) with lithium amidinates or guanidinates resulted in molybdenum(VI) complexes [(ArN)(2)-MoCl(N(R-1)C(R-2)N(R-1))] (R-1 = Cy (cyclohexyl), R-2 = Me (2); R-1 = Cy, R-2 = N(i-Pr)(2) (3); R-1 = Cy, R-2 = N(SiMe3)(2) (4); R-1 = SiMe3, R-2 = C6H5 (5)) with five coordinated molybdenum atoms. Methylation of these compounds was exemplified by the reactions of 2 and 3 with MeLi affording the corresponding methylates [(ArN)(2)MoMe(N(R-1)C(R-2)N(R-1))] (R-1 = Cy, R-2 = Me (6); R-1 = Cy, R-2 = N(i-Pr)(2) (7)). The analogous reaction of 1 with bulky [N(SiMe3)C(C6H5)-C(SiMe3)(2)]Li . THF did not give the corresponding metathesis product, but a Schiff base adduct [(ArN)(2)MoCl2]. [NH=C(C6H5)CH(SiMe3)(2)] (8) in low yield. The molecular structures of 7 and 8 are established by the X-ray single crystal structural analysis
Propolin C from Propolis Induces Apoptosis through Activating Caspases, Bid and Cytochrome C Release in Human Melanoma Cells
No full textWe had demonstrated that two prenylflavanones, propolin A and propolin B, isolated and characterized from Taiwanese propolis, induced apoptosis in human melanoma cells and significantly inhibited xanthine oxidase activity . Here, we have isolated a third compound called propolin C. The chemical structure of propolin C has been characterized by NMR and HRMS spectra, and was identical to nymphaeol-A. However, no biological activities of this compound have ever been reported. In the present study, propolin C effectively induced a cytotoxic effect on human melanoma cells, with an IC 50 of about 8.5 muM. DNA flow cytometric analysis indicated that propolin C actively induced apoptosis in human melanoma cells and there is a marked loss of cells from the G2/M phase of the cell cycle. To address the mechanism of the apoptosis effect of propolin C, we evaluated the effect of propolin C on induction of apoptosis -related proteins in human melanoma cells. The levels of procaspase-8, Bid, procaspase-3, and poly( ADP-ribose) polymerase were decreased in dose- or time course-dependent manners. Moreover, propolin C was capable of releasing cytochrome c from mitochondria to cytosol. The findings suggest that propolin C may activate a mitochondria-mediated apoptosis pathway. On other hand, propolin C is a potential antioxidant agent and shows a strong capability to scavenge free radicals and inhibit on xanthine oxidase activity with IC50 of about 17.0 muM. In conclusion, the isolation and characterization of propolin C from bee propolis are described for the first time, and this compound is a powerful inducer of apoptosis in human melanoma cells. (C) 2003 Elsevier Inc. All rights reserved
O. A. C. Review Volume LI Issue 6, March 1939
No full textThe Editorial comments on the College's successful school year in championships, College Royal, and the theatre production of H. M. S. Pinafore. Articles in this issue include the anticipation of Lord Tweedsmuir speaking at the Canadian Authors' evening, a student's travel diary of bicycling through Europe, and the annual Ontario Ice Cream Manufacturers conference. An article is devoted to the history of the O. A. C. Co-operative Store initiated by the College students in 1912. For the 15th year, the annual College Royal was an outstanding success. The agricultural article pertains to chemistry and farming. The English column summarizes the proper use of language, and includes a letter from an alumnus living in Sudbury. Campus news reviews several campus personalities, the Year 1940 Dance, candid photographs from across campus, student humour, and escapades of preparing for College Royal. Brothers Chippy and Chap Chapman produce the Sports column and provide the team results for basketball, wrestling, boxing, fencing, swimming, and hockey. The centrefold is devoted to the athletic champions at the College. The literature column highlights the production of the operetta H. M. S. Pinafore. Alumni news announces that the new Jacobine Jones sculpture is the Year '31 trophy for College Royal. The Macdonald Alumnae column provides alumnae updates and marriage announcements. The Macdonald Institute column highlights how the demonstrations preformed by the students can be a stressful situationEditorialO. A. C. awaits a distinguished visitorThe O. A. C. Co-operative storeThe chemist goes farmingEurope from a bicycleThe 1939 College RoyalWinners and trophies at the College RoyalLetters to the EditorDepartment of EnglishPioneering at SudburyCollege lifeCandid camera reviews college lifeSportsA college of championsLiteratureIce cream conferenceAlumni newsMacdonald alumnaeMacdonald new
O. A. C. Review Volume LI Issue 2, November 1938
No full textThis issue begins with an editorial on compulsory attendance at lectures and the debate it has created amongst students. A student writes of his work with Western Canadian farmers affected by drought, soil reclamation, and the Prairie Farm Rehabilitation Act. Student contributed articles report on student involvement with the Danforth Foundation Fellowship, a tobacco farmer's perspective on tobacco farming, and grain harvesting with a motorized combine. The English department column provides Professor Stevenson's anecdotes on English usage. A history and explanation of the coat of arms for the Ontario Agricultural College is located on page 86. Two professors contribute an article on the use of electric fencing in Ontario. H. Y. Chang contributes an article on establishing the first newspaper for rural China. Campus news pertains to campus humour, the numerous dances and proms held during the autumn, and unfavourable news coverage about the student initiation. The Literary column presents articles regarding guest debaters from Australia, the public speaking contest, Student Christian Movement activities, and book reviews (including the book The Third Reich). The centrefold is devoted to the history of the O. A. C. band. The athletics column provides updates of the sports: soccer, cross-country running, and football. The Macdonald Institute column introduces the Mac Class presidents, the events held at Community House, and the results of the women's swim meet. The Macdonald Alumnae column provides the current occupations and addresses of the 1938 graduates. The Alumni column includes alumni updates, marriage announcements, and an updated graduate list. Other articles report on the Kiwanis International involvement in agriculture, the latest food research at the Trent Institute on campus, and items from the O. V. C. reporter.EditorialScience in Canada's drought areaThirty-seven states - and CanadaTobacco as the grower sees itHarvesting with a combineBook reviewsDepartment of EnglishOur Coat Of Arms"One-wire" fences in OntarioThe first newspaper for rural ChinaCollege lifeThis life of oursTwo views on compromiseLiterary highlightsThe O. A. C. bandO. A. C. sportsfolioMacdonald newsMacdonald AlumnaeAlumni newsKiwanis in agricultureLetters to the editorTrent Institute and O. V. C.Our neighborsChanges in graduate listadvertisin
Li, C.P. -- 1976-82 -- Correspondence, Individual -- letter, 1976-09-07
No full textLetter from Li, C. P. to Sabin, Albert B. dated 1976-09-07.Sabin Collection Fair Use Policy</a
Catalytic role for Arginine 188 in the C-C hydrolase catalytic mechanism for Escherichia coli MhpC and Burkholderia xenovorans LB400 BphD
No full textThe alpha/beta-hydrolase superfamily, comprised mainly of esterase and lipase enzymes, contains a family of bacterial C-C hydrolases, including MhpC and BphD which catalyze the hydrolytic C-C cleavage of meta-ring fission intermediates on the Escherichia coli phenylpropionic acid pathway and Burkholderia xenovorans LB400 biphenyl degradation pathway, respectively. Five active site amino acid residues (Arg-188, Asn-109, Phe-173, Cys-261, and Trp-264) were identified from sequence alignments that are conserved in C-C hydrolases, but not in enzymes of different function. Replacement of Arg-188 in MhpC with Gln and Lys led to 200- and 40-fold decreases, respectively, in k(cat); the same replacements for Arg-190 of BphD led to 400- and 700-fold decreases, respectively, in k(cat). Pre-steady-state kinetic analysis of the R188Q MhpC mutant revealed that the first step of the reaction, keto-enol tautomerization, had become rate-limiting, indicating that Arg-188 has a catalytic role in ketonization of the dienol substrate, which we propose is via substrate destabilization. Mutation of nearby residues Phe-173 and Trp-264 to Gly gave 4-10-fold reductions in k(cat) but 10-20-fold increases in K-m, indicating that these residues are primarily involved in substrate binding. The X-ray structure of a succinate-H263A MhpC complex shows concerted movements in the positions of both Phe-173 and Trp-264 that line the approach to Arg-188. Mutation of Asn-109 to Ala and His yielded 200- and 350-fold reductions, respectively, in k(cat) and pre-steady-state kinetic behavior similar to that of a previous S110A mutant, indicating a role for Asn-109 is positioning the active site loop containing Ser-110. The catalytic role of Arg-188 is rationalized by a hydrogen bond network close to the C-1 carboxylate of the substrate, which positions the substrate and promotes substrate ketonization, probably via destabilization of the bound substrate
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