ABSTRACT
The Wang–Silk approximation, Q−1≈Q−1stars+Q−1gas, is frequently used for estimating the effective Q parameter in two‐component discs of stars and gas. Here we analyse this approximation in ...detail, and show how its accuracy depends on the radial velocity dispersions and Toomre parameters of the two components. We then propose a much more accurate but still simple approximation for the effective Q parameter, which further takes into account the stabilizing effect of disc thickness. Our effective Q parameter is a natural generalization of Toomre’s Q, and as such can be used in a wide variety of contexts, e.g. for predicting star formation thresholds in galaxies or for measuring the stability level of galactic discs at low and high redshifts.
A series of novel biaryl ureas containing different structural patterns have been prepared in good yields in the presence of palladium nanoparticles (PdNPs) with narrow particle size distribution. In ...particular, α, β‐, and γ‐hydroxypropylated cyclodextrins were used as reductants/stabilizers under different Pd‐to‐cyclodextrin ratios to tune the particle size and exploit the surface/cavity effects in the Suzuki–Miyaura reaction. Catalyst recovery in this process was pursued as well. Owing to its excellent performance, ceria was explored as a support for these PdNPs. The heterogeneous catalyst was characterized and investigated in the reaction of N‐(4‐iodo‐aryl),N′‐alkyl urea and phenylboronic acid. Our preliminary results revealed a high activity of the catalyst at 0.5 mol % Pd0 during three consecutive cycles. It is suggested that the specific interface between Pd0 and the high‐surface‐area ceria has a role in the catalytic performance.
Nanoparticle urea synthesis: Palladium nanoparticles (PdNPs) stabilized by different cyclodextrins (CDs) are used as catalysts for the synthesis of novel biaryl ureas, high‐value precursors of pharmaceuticals and supramolecular hosts. The catalytic results showed that particle sizes were not decisive, in contrast to the size of glyconanocavities. The catalytic results were improved by using a heterogeneous approach involving Pd‐CD@doped ceria.
The present study aims to resolve the taxonomic confusion involving several taxa within Mycetophagidae Leach, 1815, originating from the introduction of the genus Atritomus Reitter, 1877, and then by ...its subsequent controversial interpretation. A detailed overview of the taxonomic and nomenclatural history of the taxa previously linked to Atritomus is provided. The authors propose the introduction of Stereophilus Biscaccianti, Audisio & Esser gen. nov. for Atritomus filicornis Reitter, 1887, and the restoration of Entoxylon Ancey, 1869 at the genus rank, together with some rectifications regarding the authorship and the date of publication of both Entoxylon and its type species, E. abeillei Ancey, 1869. Moreover, the Ethiopian species Atritomus vicinus Grouvelle, 1908 is herein transferred to the genus Typhaeola Ganglbauer, 1899 based on the examination of the holotype. The following new combinations are proposed: Entoxylon baudii (Seidlitz, 1889) comb. nov. (from Esarcus Reiche, 1864), Entoxylon besucheti (Dajoz, 1964) comb. nov. (from Esarcus subg. Entoxylon), Entoxylon franzi (Dajoz, 1964) comb. nov. (from Esarcus subg. Entoxylon), Entoxylon inexpectatus (Dajoz, 1964) comb. nov. (from Esarcus subg. Entoxylon), Entoxylon martini (Reitter, 1887) comb. nov. (from Esarcus), Stereophilus filicornis (Reitter, 1887) gen. et comb. nov. (from Atritomus), Typhaeola vicina (Grouvelle, 1908) comb. nov. (from Atritomus).
Long-term insulin independence after islet transplantation depends on engraftment of a large number of islets. However, the yield of pancreatic islets from brain-dead donors is negatively affected by ...the up-regulation of inflammatory mediators. Brain death is also believed to increase tissue factor (TF) expression, contributing to a low rate of engraftment.
We conducted a case-control study to assess brain death-induced inflammatory effects in human pancreas. Seventeen brain-dead patients and 20 control patients undergoing pancreatectomy were studied. Serum tumor necrosis factor (TNF), interleukin (IL) 6, IL-1β, interferon (IFN) γ, and TF were measured using enzyme-linked immunosorbent assay kits. Gene expressions of these cytokines and TF were evaluated by reverse transcriptase quantitative polymerase chain reaction. Protein quantification was performed by immunohistochemistry in paraffin-embedded pancreas sections.
Brain-dead patients had higher serum concentrations of TNF and IL-6 and increased TNF protein levels compared to controls. The groups had similar TNF, IL-6, IL-1β, and IFN-γ messenger RNA levels in pancreatic tissue. Reverse transcriptase quantitative polymerase chain reaction revealed TF messenger RNA up-regulation in controls. Immunohistochemical analyses showed that brain-dead patients had increased TNF protein levels compared to controls.
Brain death induces inflammation evidenced by the up-regulation of TNF in serum and pancreatic tissue. Blocking the expression of key inflammatory mediators in brain-dead donors should be evaluated as a new approach to improve the outcomes of islet transplantation.
Epigenetic deregulation may be involved in tumor cell biology, including differentiation, tumor progression, and cell death, and histone acetylation is a major regulatory mechanism of gene ...transcription. Patterns of global histone modifications have been recently suggested as outcome predictors in cancer patients, but few studies have been conducted on pancreatic ductal adenocarcinomas (PDACs). This study was designed to investigate the predictive value of histone acetylation modifications on PDAC.
A retrospective clinicopathologic analysis was undertaken in 119 patients diagnosed with PDAC between 2005 and 2011, and immunohistochemistry performed with polyclonal antibodies against H4K12ac, H3K9ac, and H3K18ac. Positive nuclear staining for each histone was measured as the intensity and expression, being classified into low-staining or high-staining groups. Results were analyzed in relation to patients' clinicopathologic parameters.
There was a positive relationship between tumor differentiation and H4K12ac high scores (P<0.05) and staining with the 3 markers correlated positively with tumor stage (P<0.01). Univariate analysis showed worse survival in patients with high detection levels of H4K12ac (P=0.038) and H3K18Ac (P=0.033). A backwards Cox proportional hazards model analysis revealed the independent prognostic effect of high H4K12ac and H3K18ac levels (hazard ratios of 1.6 and 1.7, respectively, P<0.05), especially for patients at early stages of disease.
We propose that acetylation of H4K12 and H3K18 may be considered valuable prognostic factors for pancreatic cancer, although the mechanism involved needs further investigation. Increasing insights into histone acetylation modifications can ultimately generate new ideas for rational and molecularly based diagnostic and therapeutic approaches.
From giant clumps to clouds Renaud, Florent; Agertz, Oscar; Romeo, Alessandro B
Astronomy and astrophysics (Berlin),
07/2024, Letnik:
687
Journal Article
Recenzirano
The clumpy nature of gas-rich galaxies at cosmic noon raises the question of universality of the scaling relations and average properties of the star-forming structures. Using controlled simulations ...of disk galaxies and varying only the gas fraction, we show that the influence of the galactic environments (large-scale turbulence, tides, and shear) contributes, together with the different regime of instabilities, to setting a diversity of physical conditions for the formation and evolution of gas clumps from low to high gas fractions. However, the distributions of gas clumps at all gas fractions follow similar scaling relations as Larson’s, suggesting the universality of median properties. Yet, we find that the scatter around these relations significantly increases with the gas fraction, allowing for the presence of massive, large, and highly turbulent clouds in gas-rich disks in addition to a more classical population of clouds. Clumps with an excess of mass for their size are slightly denser, more centrally concentrated, and host more abundant and faster star formation. We find that the star formation activity (rate, efficiency, and depletion time) correlates much more strongly with the excess of mass than with the mass itself. Our results suggest the existence of universal scaling relations for gas clumps but with redshift-dependent scatters, which calls for deeper and more complete census of the populations of star-forming clumps and young stellar clusters at cosmic noon and beyond.
This paper shows the production of lipase B from Candida antarctica (LIPB) after cloning the gene that encoded it in Pichia pastoris using PGK as a constitutive promoter. The production of the lipase ...is lower using this strategy but it avoids the use of inducers like methanol. The performance of this enzyme was compared with that of the commercial enzyme (CALB) after immobilization on different supports in different reactions. As supports, we used Accurel 1000, and three core-shell supports (poly(methyl methacrylate) on the core and on the shell - PMMA/PMMA; poly(methyl methacrylate-co-divinylbenzene) on the core and on the shell - PMMA-co-DVB/PMMA-co-DVB; and poly(styrene-co-divinylbenzene) on the core and on the shell - PS-co-DVB/PS-co-DVB). The popular Novozym 435 was also utilized to assess the features of the new biocatalysts. All these supports adsorbed lipases via interfacial activation of the open form of the lipase on the hydrophobic surface of the supports. The studied reactions were esterification of oleic acid and ethanol in a solvent-free medium, resolution of ( plus or minus )-1,3,5-O-benzyl-myo-inositol via acylation using vinyl acetate in hexane and resolution of ( plus or minus )-1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol via acylation using vinyl acetate (solvent free system). The results varied depending on the employed supports and on the studied reactions, but some general trends may be observed, pointing to better behavior of LIPB compared to CALB. The use of 4 different supports gave more strength to these differences, as it did not depend on a specific difference between a single support/enzyme pair, but it is more general. Thus, LIPB seems to have some advantages compared to the commercial enzyme on all the reactions assayed in this paper. PS-co-DVB/PS-co-DVB-LIPB is in general the most active preparation (even 50% higher activity was observed). Further investigations are in development to determine the structural reasons for these differences.
The use of stable isotope analysis as a tool for characterization of carbon turnover (δ13C) in piglet's tissues by tracing its feeding system has drawn attention. Thus, this study aimed at evaluating ...the influence of dietary glutamine, glutamic acid and nucleotides supplementation on carbon turnover in fundic-stomach region of weaned piglets at an average age of 21 days. The diets consisted of additive-free diet – control (C); 1% glutamine (G); 1% glutamic acid (GA) and 1% nucleotides (Nu). At weaning day (day 0: baseline), 3 piglets were slaughtered to quantify the δ13C of stomach. The remaining 120 piglets were blocked by weight and sex, randomly assigned to pens with 3 piglets slaughtered per treatment at days 1, 2, 4, 5, 7, 9, 13, 20, 27 and 49 after weaning in order to verify the fundic-stomach isotopic composition by treatments. Samples were analyzed in terms of 13C/12C ratio by mass spectrometry and converted to relative isotopic enrichment values (δ13C ‰) used to plot the first order exponential curves over time using OriginPro 8.0 software. The inclusion of glutamine, glutamate and nucleotides in piglet's diets has accelerated the carbon turnover in stomach during the post-weaning period, demonstrating also that glutamate has guaranteed fastest 13C incorporation rate on fundic-stomach region and pH-lowering. Besides that, stable isotopes technique (δ13C) has proved to be an important methodology to determine the time-scales at which piglets shift among diets with different isotopic values, characterizing the trophic effects of additives and the phenotypic flexibility of stomach.
We report a new measurement of J/ψ, ψ′ and Drell–Yan cross-sections, in the kinematical domain -0.425<ycm<0.575 and -0.5<cosθCS<0.5, performed at the CERN-SPS using 400 GeV/c incident protons on Be, ...Al, Cu, Ag, W and Pb targets. The dependence of the charmonia production cross-sections on the size of the target nucleus allows to quantify the so-called normal nuclear absorption. In the framework of the Glauber model, this new measurement is combined with results previously obtained with the same apparatus, under different experimental conditions, and leads to a precise determination of the J/ψ and ψ′ absorption cross-sections in the surrounding nuclear matter.
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