902 research outputs found
A Lower Estimate for the Modified Steiner Functional
We prove inequality (1) for the modified Steiner functional A(M), which
extends the notion of the integral of mean curvature for convex surfaces.We
also establish an exression for A(M) in terms of an integral over all
hyperplanes intersecting the polyhedralral surface M.Comment: 6 pages, Late
Coke steam reforming in FCC regenerator: A new mastery over high coking feeds
[EN] One of the crucial problems of processing residual feeds in the FCC is their high coking tendency, which limits their use in the FCC and requires them to be mixed with lighter feeds to be processed in conventional FCC units. A step-out improvement of the FCC process to use in processing heavy feeds is presented, where the heat balance in the unit is maintained by removing the high coke-on-catalyst by a combination of coke combustion and reforming, i.e., coke steam reforming (CSR) in the regenerator. This option enables using feeds with more than 10% Conradson Carbon while still maintaining the possibility to control the heat balance in the unit without using partial combustion or catalyst coolers. Although the Equilibrium catalyst has little CSR activity, we have found that hydrotalcite materials, besides having an excellent catalytic cracking selectivity for heavy feeds, also have significant CSR activity. We have demonstrated that CSR can be performed together with combustion at conditions found in the FCC regenerator so that the regenerator temperature remains within traditional limits despite higher coke-on-catalyst, and the coke on the catalyst is nearly completely removed. While the reaction rate at higher temperatures seems to obey first order, steam reforming coke removal kinetics at lower (750 degrees C) temperatures seem more complex due to the heterogeneous nature of coke.The authors thank BP Products North America and Consolider-Ingenio 2010 (MULTICAT project) for their financial support and permission to publish this work.Corma Canós, A.; Sauvanaud ., LL.; Doskocil, E.; Yaluris, G. (2011). Coke steam reforming in FCC regenerator: A new mastery over high coking feeds. Journal of Catalysis. 279(1):183-195. https://doi.org/10.1016/j.jcat.2011.01.020S183195279
Role of the compaction energy level on the small strain stiffness of a silty sand soil subjected to wetting and drying
The dynamic properties of a soil are routinely quantified to describe its engineering behaviour under repeated loading. While the results of previous research studies indicate that the effect of changes in suction on the dynamic response is significant, only limited research has been engaged in the assessment of post-compacted changes in suction induced by cycles of wetting and drying. In this paper, aspects related to the dynamic properties with special reference to small strain shear modulus behaviour at different compaction energy levels are described and outlined. Particular emphasis is placed on the hysteric behaviour observed (i.e. amplitude of the hysteresis loop) and its dependence on the imparted compaction energy. The results not only confirm the importance of the recent suction ratio (or CSR) in governing the mechanical response at small strain, but they also indicate that higher compaction energy levels induce smaller hysteresis loops
Risk of hepatocellular carcinoma in chronic hepatitis B: Assessment and modification with current antiviral therapy
SummaryIn the treatment of chronic hepatitis B (CHB), the ultimate goal is preventing hepatitis B virus (HBV)-associated liver disease, including hepatocellular carcinoma (HCC). Recently published studies show that in CHB patients treated with the currently recommended first-line nucleos(t)ide analogs (NAs) entecavir or tenofovir, annual HCC incidences range from 0.01% to 1.4% in non-cirrhotic patients, and from 0.9% to 5.4% in those with cirrhosis. In Asian studies including matched untreated controls, current NA therapy consistently resulted in a significantly lower HCC incidence in patients with cirrhosis, amounting to an overall HCC risk reduction of ∼30%; in non-cirrhotic patients, HCC risk reduction was overall ∼80%, but this was only observed in some studies. For patients of Caucasian origin, no appropriate comparative studies are available to date to evaluate the impact of NA treatment on HCC. Achievement of a virologic response under current NA therapy was associated with a lower HCC risk in Asian, but not Caucasian studies. Studies comparing entecavir or tenofovir with older NAs generally found no difference in HCC risk reduction between agents, except for one study which used no rescue therapy in patients developing lamivudine resistance. Overall, these data indicate that with the current, potent NAs, HCC risk can be reduced but not eliminated, probably due to risk factors that are not amenable to change by antiviral therapy, or events that may have taken place before treatment initiation. Validated pre- and on-therapy HCC risk calculators that inform the best practice for HCC surveillance and facilitate patient counseling would be of great practical value
Monitoring of unbound protein in vesicle suspensions with off-null ellipsometry
In studies on the binding of proteins to small unilamellar phospholipid vesicles (SUV), the concentration of unbound protein usually remains unknown, because the vesicles cannot be separated from the bulk solution. In the present study, this limitation was overcome by addition of a supported planar phospholipid bilayer to the cuvette containing a vesicle suspension. Ellipsometric measurement of the protein adsorption velocities on this bilayer allowed determination of the concentrations of unbound protein. At high protein concentrations the adsorption is rapidly completed and the usual null-ellipsometry is too slow to obtain well-defined initial adsorption rates. Therefore, an off-null technique was developed, allowing measurement of the adsorbed protein mass at time intervals of 20 ms. Binding of prothrombin and coagulation factor Xa was measured in SUV suspensions prepared from a 20Va dioleoylphosphatidylserine (DOPS) and 80Vo dioleoylphosphatidylcholine (DOPC) phospho-lipid mixture. For prothrombin, a dissociation constant Kd:140+27 nM (mean*S.E.) and maximal surface concentration fL".: (8.9 + 0.8) ' 10- 3 mole of protein per mole of lipid, were obtained. For factor Xa, these values were K d: 49.6 + 6.3 nM and 1-u *:Q3.0 t 1.4) ' 10-3 mole of protein per mole of lipid. These binding parameters are similar to those obtained earlier for planar bilayers. Apparently, the binding of factor Xa and prothrombin is not dependent on surface curvature. r2
GPCR-OKB: the G protein coupled receptor oligomer knowledge base
Rapid expansion of available data about G Protein Coupled Receptor (GPCR) dimers/oligomers over the past few years requires an effective system to organize this information electronically. Based on an ontology derived from a community dialog involving colleagues using experimental and computational methodologies, we developed the GPCR-Oligomerization Knowledge Base (GPCR-OKB). GPCR-OKB is a system that supports browsing and searching for GPCR oligomer data. Such data were manually derived from the literature. While focused on GPCR oligomers, GPCR-OKB is seamlessly connected to GPCRDB, facilitating the correlation of information about GPCR protomers and oligomers
Toeplitz operators on symplectic manifolds
We study the Berezin-Toeplitz quantization on symplectic manifolds making use
of the full off-diagonal asymptotic expansion of the Bergman kernel. We give
also a characterization of Toeplitz operators in terms of their asymptotic
expansion. The semi-classical limit properties of the Berezin-Toeplitz
quantization for non-compact manifolds and orbifolds are also established.Comment: 40 page
Equidistribution of zeros of holomorphic sections in the non compact setting
We consider N-tensor powers of a positive Hermitian line bundle L over a
non-compact complex manifold X. In the compact case, B. Shiffman and S.
Zelditch proved that the zeros of random sections become asymptotically
uniformly distributed with respect to the natural measure coming from the
curvature of L, as N tends to infinity. Under certain boundedness assumptions
on the curvature of the canonical line bundle of X and on the Chern form of L
we prove a non-compact version of this result. We give various applications,
including the limiting distribution of zeros of cusp forms with respect to the
principal congruence subgroups of SL2(Z) and to the hyperbolic measure, the
higher dimensional case of arithmetic quotients and the case of orthogonal
polynomials with weights at infinity. We also give estimates for the speed of
convergence of the currents of integration on the zero-divisors.Comment: 25 pages; v.2 is a final update to agree with the published pape
Reduced Toxicity Conditioning (RTC) and Allogeneic Stem Cell Transplantation (alloSCT) in 100 Consecutive Pediatric Recipients: Very Low Incidence of Day 100 Transplant Related Mortality (TRM)
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