Graphene cover-promoted metal-catalyzed reactions Yao, Yunxi; Fu, Qiang; Zhang, Y. Y. ...
Proceedings of the National Academy of Sciences - PNAS,
12/2014, Letnik:
111, Številka:
48
Journal Article
Recenzirano
Odprti dostop
Graphitic overlayers on metals have commonly been considered as inhibitors for surface reactions due to their chemical inertness and physical blockage of surface active sites. In this work, however, ...we find that surface reactions, for instance, CO adsorption/desorption and CO oxidation, can take place on Pt(111) surface covered by monolayer graphene sheets. Surface science measurements combined with density functional calculations show that the graphene overlayer weakens the strong interaction between CO and Pt and, consequently, facilitates the CO oxidation with lower apparent activation energy. These results suggest that interfaces between graphitic overlayers and metal surfaces act as 2D confined nanoreactors, in which catalytic reactions are promoted. The finding contrasts with the conventional knowledge that graphitic carbon poisons a catalyst surface but opens up an avenue to enhance catalytic performance through coating of metal catalysts with controlled graphitic covers.
Significance Carbon deposits have been widely observed on metal surfaces in a variety of catalytic reactions, and the graphitic carbon species are often considered as inhibitors for surface reactions. We demonstrate here that CO adsorption and oxidation can occur on Pt surface covered by monolayer graphene, showing that the space between graphene overlayer and metal surface can act as a two-dimensional (2D) nanoreactor. Inside, CO oxidation happens with lower activation barrier due to the confinement effect of the graphene cover. This finding reminds us to reconsider the role of graphitic carbon in metal-catalyzed surface reactions and further provides a way to design novel catalysts.
► NH
3-TPD and Py-FT-IR spectra verified that the addition of nickel and aluminum enhanced remarkably Lewis acid sites. ► Higher breakthrough sulfur capacity correlated with more acidic sites. ► ...Presence of aromatic compounds in diesel reduced the adsorption of thiophene and derivatives.
Nickel particles supported on mesoporous MCM-41 or AlMCM-41 (SiO
2/Al
2O
3
=
30, 50) sorbents were prepared by an incipient wetness impregnation (IWI) of nickel nitrate and the ultra-deep desulfurization properties for model fuels or diesel were evaluated under ambient conditions. Among the tested sorbents, 15%Ni-AlMCM-41 (30) presented the highest sulfur adsorption capacity toward thiophene, benzothiophene and commercial diesel. The pore structure, acidic sites and surface features of the sorbents were characterized by means of BET, XRD, NH
3-TPD, Py-FT-IR and XPS techniques, it revealed that Lewis acidic sites played important role in the removal of organic sulfur compounds over reduced 15%Ni-AlMCM-41 (30). After regeneration of used sorbent, approximately 100% of organic sulfur adsorption capacity was recovered.
Myeloid-derived suppressor cells (MDSCs) contribute to tumour immunosuppressive microenvironment and immune-checkpoint blockade resistance. Emerging evidence highlights the pivotal functions of ...cyclin-dependent kinases (CDKs) in tumour immunity. Here we elucidated the role of tumour-intrinsic CDK20, or cell cycle-related kinase (CCRK) on immunosuppression in hepatocellular carcinoma (HCC).
Immunosuppression of MDSCs derived from patients with HCC and relationship with CCRK were determined by flow cytometry, expression analyses and co-culture systems. Mechanistic studies were also conducted in liver-specific
-inducible transgenic (TG) mice and Hepa1-6 orthotopic HCC models using CRISPR/Cas9-mediated
depletion and liver-targeted nanoparticles for interleukin (IL) 6 trapping. Tumorigenicity and immunophenotype were assessed on single or combined antiprogrammed death-1-ligand 1 (PD-L1) therapy.
Tumour-infiltrating CD11b
CD33
HLA-DR
MDSCs from patients with HCC potently inhibited autologous CD8
T cell proliferation. Concordant overexpression of CCRK and MDSC markers (CD11b/CD33) positively correlated with poorer survival rates. Hepatocellular CCRK stimulated immunosuppressive CD11b
CD33
HLA-DR
MDSC expansion from human peripheral blood mononuclear cells through upregulating IL-6. Mechanistically, CCRK activated nuclear factor-κB (NF-κB) via enhancer of zeste homolog 2 (EZH2) and facilitated NF-κB-EZH2 co-binding to
promoter. Hepatic
induction in TG mice activated the EZH2/NF-κB/IL-6 cascade, leading to accumulation of polymorphonuclear (PMN) MDSCs with potent T cell suppressive activity. In contrast, inhibiting tumorous
or hepatic IL-6 increased interferon γ
tumour necrosis factor-α
CD8
T cell infiltration and impaired tumorigenicity, which was rescued by restoring PMN-MDSCs. Notably, tumorous
depletion upregulated PD-L1 expression and increased intratumorous CD8
T cells, thus enhancing PD-L1 blockade efficacy to eradicate HCC.
Our results delineate an immunosuppressive mechanism of the hepatoma-intrinsic CCRK signalling and highlight an overexpressed kinase target whose inhibition might empower HCC immunotherapy.
Background
The overproduction of IgE plays a critical role in the pathogenesis of allergy; the mechanism is unclear. Histone‐acetyltransferase (HAT) activities are required in gene transcription of a ...large number of molecules in the immune system of the body.
Objectives
This study tests a hypothesis that HAT Tat‐interactive protein 60 (Tip60) plays an important role in the initiation of IgE‐mediated allergy.
Methods
The effects of Tip60 on regulating IgE expression were assessed with B cells. An intestinal allergy mouse model was developed to assess the role of Tip60 in the induction of IgE‐mediated allergic inflammation.
Results
High levels of Tip60 were observed in the peripheral B cells of patients with FA. Tat‐interactive protein 60 (Tip60) was required in the expression of IgE and IgG1 in B cells by inducing the chromatin remolding at the gene locus, in which histone acetylation, signal transducer and activator of transcription 6 (STAT6), and nuclear factor‐κB at the locus of Iε promoter were markedly increased. Blocking Tip60 significantly attenuated the allergic inflammation in the mouse intestinal mucosa.
Conclusions
Tat‐interactive protein 60 (Tip60) plays an important role in the induction of IgE in B cells. Blocking Tip60 inhibits the allergic inflammation in the intestine, suggesting Tip60 inhibitor may be a potential anti‐allergy drug.
Ultrasound is a critical non-invasive test for preoperative diagnosis of ovarian cancer. Deep learning is making advances in image-recognition tasks; therefore, we aimed to develop a deep ...convolutional neural network (DCNN) model that automates evaluation of ultrasound images and to facilitate a more accurate diagnosis of ovarian cancer than existing methods.
In this retrospective, multicentre, diagnostic study, we collected pelvic ultrasound images from ten hospitals across China between September 2003, and May 2019. We included consecutive adult patients (aged ≥18 years) with adnexal lesions in ultrasonography and healthy controls and excluded duplicated cases and patients without adnexa or pathological diagnosis. For DCNN model development, patients were assigned to the training dataset (34 488 images of 3755 patients with ovarian cancer, 541 442 images of 101 777 controls). For model validation, patients were assigned to the internal validation dataset (3031 images of 266 patients with ovarian cancer, 5385 images of 602 with benign adnexal lesions), external validation datasets 1 (486 images of 67 with ovarian cancer, 933 images of 268 with benign adnexal lesions), and 2 (1253 images of 166 with ovarian cancer, 5257 images of 723 benign adnexal lesions). Using these datasets, we assessed the diagnostic value of DCNN, compared DCNN with 35 radiologists, and explored whether DCNN could augment the diagnostic accuracy of six radiologists. Pathological diagnosis was the reference standard.
For DCNN to detect ovarian cancer, AUC was 0·911 (95% CI 0·886–0·936) in the internal dataset, 0·870 (95% CI 0·822–0·918) in external validation dataset 1, and 0·831 (95% CI 0·793–0·869) in external validation dataset 2. The DCNN model was more accurate than radiologists at detecting ovarian cancer in the internal dataset (88·8% vs 85·7%) and external validation dataset 1 (86·9% vs 81·1%). Accuracy and sensitivity of diagnosis increased more after DCNN-assisted diagnosis than assessment by radiologists alone (87·6% 85·0–90·2 vs 78·3% 72·1–84·5, p<0·0001; 82·7% 78·5–86·9 vs 70·4% 59·1–81·7, p<0·0001). The average accuracy of DCNN-assisted evaluations for six radiologists reached 0·876 and were significantly augmented when they were DCNN-assisted (p<0·05).
The performance of DCNN-enabled ultrasound exceeded the average diagnostic level of radiologists matched the level of expert ultrasound image readers, and augmented radiologists’ accuracy. However, these observations warrant further investigations in prospective studies or randomised clinical trials.
National Key Basic Research Program of China, National Sci-Tech Support Projects, and National Natural Science Foundation of China.
Abstract
We present a timing study of the short-period eclipsing cataclysmic variable (CV) HT Cas. Based on new eclipse times derived from our photometric monitoring and archival optical data, ...combined with historical timings, spanning ∼42 yr, we detect a secular decrease in the orbital period at a rate of
P
̇
=
−
1.32
×
10
−
12
ss
−
1
and a cyclic period wiggle with an amplitude of 79.3 s and a period of 30.28 yr. We find that neither gravitational radiation nor magnetic braking can explain the observed decrease rate, suggesting the presence of additional angular momentum loss (AML). The empirical consequential AML (eCAML) model developed by Schreiber et al. can well match the observed orbital decay in HT Cas, and the physical mechanism for eCAML is most likely attributable to the frictional AML following nova eruptions. As for the cyclic variation, the best explanation is the influence of an unseen companion in orbit around the binary. The derived orbital parameters reveal that the hypothetical third body could be a giant planet with mass of
M
3
≃ 14
M
Jup
that is moving on a highly eccentric orbit (
e
= 0.82). Taken together the results of the present study suggest that HT Cas is a unique triple system containing a high-eccentricity giant planet and it has the potential to become an ideal laboratory in which to test models of CV evolution.
Background & Aims Subtle inter-patient genetic variation and environmental factors combine to determine disease progression in non-alcoholic fatty liver disease (NAFLD). Carriage of the PNPLA3 ...rs738409 c.444C >G minor allele (encoding the I148M variant) has been robustly associated with advanced NAFLD. Although most hepatocellular carcinoma (HCC) is related to chronic viral hepatitis or alcoholic liver disease, the incidence of NAFLD-related HCC is increasing. We examined whether rs738409 C >G was associated with HCC-risk in patients with NAFLD. Methods PNPLA3 rs738409 genotype was determined by allelic discrimination in 100 European Caucasians with NAFLD-related HCC and 275 controls with histologically characterised NAFLD. Results Genotype frequencies were significantly different between NAFLD-HCC cases (CC = 28, CG = 43, GG = 29) and NAFLD-controls (CC = 125, CG = 117, GG = 33) ( p = 0.0001). In multivariate analysis adjusted for age, gender, diabetes, BMI, and presence of cirrhosis, carriage of each copy of the rs738409 minor (G) allele conferred an additive risk for HCC (adjusted OR 2.26 95% CI 1.23–4.14, p = 0.0082), with GG homozygotes exhibiting a 5-fold 1.47–17.29, p = 0.01 increased risk over CC. When compared to the UK general population (1958 British Birth Cohort, n = 1476), the risk-effect was more pronounced (GC vs. CC: unadjusted OR 2.52 1.55–4.10, p = 0.0002; GG vs. CC: OR 12.19 6.89–21.58, p <0.0001). Conclusions Carriage of the PNPLA3 rs738409 C >G polymorphism is not only associated with greater risk of progressive steatohepatitis and fibrosis but also of HCC. If validated, these findings suggest that PNPLA3 genotyping has the potential to contribute to multi-factorial patient-risk stratification, identifying those to whom HCC surveillance may be targeted.
Objective
To conduct a systematic review and meta‐analysis of studies that measured cytokine and chemokine levels in individuals with major depressive disorder (MDD) compared to healthy controls ...(HCs).
Method
The PubMed/MEDLINE, EMBASE, and PsycINFO databases were searched up until May 30, 2016. Effect sizes were estimated with random‐effects models.
Result
Eighty‐two studies comprising 3212 participants with MDD and 2798 HCs met inclusion criteria. Peripheral levels of interleukin‐6 (IL‐6), tumor necrosis factor (TNF)‐alpha, IL‐10, the soluble IL‐2 receptor, C‐C chemokine ligand 2, IL‐13, IL‐18, IL‐12, the IL‐1 receptor antagonist, and the soluble TNF receptor 2 were elevated in patients with MDD compared to HCs, whereas interferon‐gamma levels were lower in MDD (Hedge's g = −0.477, P = 0.043). Levels of IL‐1β, IL‐2, IL‐4, IL‐8, the soluble IL‐6 receptor (sIL‐6R), IL‐5, CCL‐3, IL‐17, and transforming growth factor‐beta 1 were not significantly altered in individuals with MDD compared to HCs. Heterogeneity was large (I2: 51.6–97.7%), and sources of heterogeneity were explored (e.g., age, smoking status, and body mass index).
Conclusion
Our results further characterize a cytokine/chemokine profile associated with MDD. Future studies are warranted to further elucidate sources of heterogeneity, as well as biosignature cytokines secreted by other immune cells.
Fe-Cr-Ni-Mn-Mo-Nb-Si steel with low transformation temperature was fabricated by direct laser deposition (DLD) and its microstructure, residual stress and properties were investigated. The results ...demonstrated that the microstructure consisted of martensite laths with a lath spacing in the nano-scale range and a small amount of nano-sized polycrystalline precipitates. There was no grain boundary segregation, and the chemical elements were homogeneously distributed. The tensile strength, yielding strength, elongation and impact energy were 1275 MPa, 1032 MPa, 12% and 57 J respectively. The comprehensive mechanical properties were equivalent with those of the wrought precipitation hardening martensitic stainless steel. There was no Cr-depleted zone at the interface between the matrix and the precipitates as well as the interior at the precipitates, and the corrosion resistance was better than that of FV520B stainless steel. The neutron diffraction (ND) stress analysis results showed that the residual tensile stress level in the cladding layer was relatively low due to the effect of solid phase transition. Consequently, due to the excellent integrated mechanical properties and the residual stress state, there was no need to conduct stress relief and precipitation hardening heat treatment, thus avoiding the influence of heat treatment on the base material properties, and saving resources and funds.
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