During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x–ray absorption and emission spectroscopy. This progress ...includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x–ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X–ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X–ray absorption experiments, and how to analyze the details of the resulting spectra. X-Ray Absorption and X-ray Emission Spectroscopy: Theory and Applications: * Combines the theory, instrumentation and applications of x-ray absorption and emission spectroscopies which offer unique diagnostics to study almost any object in the Universe. * Is the go-to reference book in the subject for all researchers across multi-disciplines since intense beams from modern sources have revolutionized x-ray science in recent years * Is relevant to students, postdocurates and researchers working on x-rays and related synchrotron sources and applications in materials, physics, medicine, environment/geology, and biomedical materials
Metal organic frameworks (MOFs) have recently debuted as participants and solid supports in catalytic water splitting. Their porosity and structural versatility offer a tantalising consolidation of ...the components needed for solar light harvesting and water splitting. Herein, we describe a selection of relevant contemporary investigations that employ electrocatalysis, chemically introduced redox partners, and photo-catalysts to generate dioxygen and dihydrogen from water. The role of semiconducting MOFs in these systems is addressed, in tandem with band gap control by linker functionalisation and doping. Considered holistically, MOFs offer an impressive physical, spatial and chemical versatility with which to support and sustain water splitting reactions. Major challenges toward practical implementation do remain, but opportunities for development are evidently numerous.
Oropharyngeal squamous cell carcinomas (OPSCCs) are traditionally caused by smoking and excessive alcohol consumption. However, in the last decades high-risk human papillomavirus (HPV) infections ...play an increasingly important role in tumorigenesis. HPV-driven OPSCCs are known to have a more favorable prognosis, which has led to important and marked changes in the recently released TNM-8. In this 8th edition, OPSCCs are divided based on p16 immunostaining, with p16 overexpression as surrogate marker for the presence of HPV. The aims of this study are to evaluate TNM-8 on a Dutch consecutive cohort of patients with p16-positive OPSCC and to determine the relevance of additional HPV DNA testing.
All OPSCC patients without distant metastases at diagnosis and treated with curative intent at VU University Medical Center (2000–2015) and Erasmus Medical Center (2000–2006) were included (N=1204). HPV status was determined by p16 immunostaining followed by HPV DNA PCR on the p16-immunopositive cases. We compared TNM-7 and TNM-8 using the Harrell’s C index.
In total, 388 of 1204 (32.2%) patients were p16-immunopositive. In these patients, TNM-8 had a markedly better predictive prognostic power than TNM-7 (Harrell’s C index 0.63 versus 0.53). Of the 388 p16-positive OPSCCs, 48 tumors (12.4%) were HPV DNA-negative. This subgroup had distinct demographic, clinical and morphologic characteristics and showed a significantly worse five-year overall survival compared with the HPV DNA-positive tumors (P<0.001).
TNM-8 has a better predictive prognostic power than TNM-7 in patients with p16-positive OPSCC. However, within p16-positive OPSCCs, there is an HPV DNA-negative subgroup with distinct features and a worse overall survival, indicating the importance to perform additional HPV DNA testing when predicting prognosis and particularly for selecting patients for de-intensified treatment regimens.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The porcine cathelicidin PR-39 is a host defence peptide that plays a pivotal role in the innate immune defence of the pig against infections. Besides direct antimicrobial activity, it is involved in ...immunomodulation, wound healing and several other biological processes. In this study, the antimicrobial- and immunomodulatory activity of PR-39, and N- and C-terminal derivatives of PR-39 were tested. PR-39 exhibited an unexpected broad antimicrobial spectrum including several Gram positive strains such as Bacillus globigii and Enterococcus faecalis. Of organisms tested, only Staphylococcus aureus was insensitive to PR-39. Truncation of PR-39 down to 15 (N-terminal) amino acids did not lead to major loss of activity, while peptides corresponding to the C-terminal part of PR-39 were hampered in their antimicrobial activity. However, shorter peptides were all much more sensitive to inhibition by salt. Active peptides induced ATP leakage and loss of membrane potential in Bacillus globigii and Escherichia coli, indicating a lytic mechanism of action for these peptides. Finally, only the mature peptide was able to induce IL-8 production in porcine macrophages, but some shorter peptides also had an effect on TNF-α production showing differential regulation of cytokine induction by PR-39 derived peptides. None of the active peptides showed high cytotoxicity highlighting the potential of these peptides for use as an alternative to antibiotics.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Host Defence Peptides and derived peptides are promising classes of antimicrobial and immunomodulatory lead compounds. For this purpose we examined whether chicken cathelicidin-2 (CATH-2)-derived ...peptides modulate the function and inflammatory response of avian immune cells. Using a chicken macrophage cell line (HD11) we found that full-length CATH-2 dose-dependently induced transcription of chemokines CXCLi2/IL-8, MCP-3 and CCLi4/RANTES, but not of pro-inflammatory cytokine IL-1β. In addition, CATH-2 efficiently inhibited IL-1β and nitric oxide production by HD11 cells induced by different sources of lipopolysaccharides (LPS). N-terminal truncated CATH-2 derived peptides maintained the capacity to selectively induce chemokine transcription, but despite their high LPS affinity several analogs lacked LPS-neutralizing capacity. Substitution of phenylalanine residues by tryptophan introduced endotoxin neutralization capacity in inactive truncated CATH-2 derived peptides. In contrast, amino acid substitution of phenylalanine by tyrosine abrogated endotoxin neutralization activity of CATH-2 analogs. These findings support a pivotal role for aromatic residues in peptide-mediated endotoxin neutralization by CATH-2 analogs and were shown to be independent of LPS affinity. The capacity to modulate chemokine production and dampen endotoxin-induced pro-inflammatory responses in chicken immune cells implicates that small CATH-2 based peptides could serve as leads for the design of CATH-2 based immunomodulatory anti-infectives.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The dynamic interactions between noble metal particles and reducible metal-oxide supports can depend on redox reactions with ambient gases. Transmission electron microscopy revealed that the strong ...metal-support interaction (SMSI)-induced encapsulation of platinum particles on titania observed under reducing conditions is lost once the system is exposed to a redox-reactive environment containing oxygen and hydrogen at a total pressure of ~1 bar. Destabilization of the metal-oxide interface and redox-mediated reconstructions of titania lead to particle dynamics and directed particle migration that depend on nanoparticle orientation. A static encapsulated SMSI state was reestablished when switching back to purely oxidizing conditions. This work highlights the difference between reactive and nonreactive states and demonstrates that manifestations of the metal-support interaction strongly depend on the chemical environment.
Host defense peptides (HDPs) play a pivotal role in innate immunity and have, in addition to antimicrobial activity, also important immunomodulatory functions. Bacteria are less likely to develop ...resistance against HDPs because these peptides target and kill bacteria in multiple ways, as well as modulate the immune system. Therefore, HDPs, and derivatives thereof, are promising alternatives to traditional antibiotics. Hardly anything is known about the immunomodulatory functions of porcine cathelicidin PMAP-36. In this study, we aimed to determine both antibacterial and immunomodulatory activities of PMAP-36 comparing the properties of PMAP-36 analogs with two well-studied peptides, human LL-37 and chicken CATH-2. Transmission electron microscopy revealed different killing mechanisms of E. coli for PMAP-36, CATH-2 and LL-37. LL-37 binds LPS very weakly in contrast to PMAP-36, but it inhibits LPS activation of macrophages the strongest. The first 11 amino acids of the N-terminal side of PMAP-36 are dispensable for E. coli killing, LPS-neutralization and binding. Deletion of four additional amino acids resulted in a strong decrease in activity. The activity of full length PMAP-36 was not affected by monomerization, whereas the shorter analogs require dimerization for proper immunomodulatory activity but not for their antibacterial activity.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Methane steam reforming on Rh/Al2O3 catalysts promoted by Sm2O3 and/or CeO2 was studied to clarify the role of the promoters on catalytic and structural properties. Promoted catalysts showed higher ...reaction rates and stability than Rh/Al2O3 due to the stronger interactions of Rh and the Sm2O3–CeO2 containing support, avoiding sintering of active phase. Display omitted
► Promoters led to higher reaction rates of Rh/Al2O3 catalysts in methane steam reforming. ► EXAFS showed instability of the Rh particles when supported on unpromoted Al2O3. ► Sm2O3 and CeO2 containing supports have stronger interaction with the active phase. ► The presence of promoters avoided sintering and oxidation of the metal particles.
The role of Sm2O3 and CeO2 promoters on the structural properties and catalytic behavior of Rh/xSm2O3–yCeO2–Al2O3 catalysts during methane steam reforming (MSR) was investigated. Promoted catalysts showed higher reaction rates per surface Rh atom and improved stability compared to Rh/Al2O3. In situ X-ray absorption revealed that the structure of Rh particles in Rh/Al2O3 changes drastically during MSR, while it was stable in the presence of Sm2O3–CeO2. Sintering of the active metal phase was the main cause of deactivation. STEM images showed stronger Rh agglomeration of the unpromoted catalyst with time on stream.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Au catalysts with different metallic particle sizes and supported on silica, alumina, titania, zirconia, ceria, and niobia were prepared, and the reduced catalysts were characterized by EXAFS ...spectroscopy. As the Au
Au coordination number decreased, the interatomic bond length decreased. The Au
Au bond length contraction appears to be independent of the support type. A correlation between the dispersion of Pt catalysts determined by hydrogen chemisorption and the EXAFS Pt
Pt coordination number was established and used to determine the dispersion of fully reduced Au catalysts. In addition, the Au particle size was estimated using a literature correlation of the EXAFS coordination number. For particles larger than about 40 Å, there was little change in the metallic bond length, whereas in catalysts with gold particles smaller than 30 Å, the Au
Au distance decreased with decreasing particle size, with a maximum contraction of about 0.15 Å. Decreasing particle size also brought a decrease in the intensity of the white line of the XANES spectrum. Both the decrease in bond distance and white line intensity were consistent with an increase in the d-electron density of Au atoms in very small particles. Au particles smaller than about 30 Å were also reactive to air, leading to oxidation of up to 15% of the atoms of the gold particles, depending on the size; larger particles were not oxidized. These oxidized Au atoms in small particles are suggested to be active for CO oxidation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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