Room temperature gas sensing properties of SnO₂/multiwall-carbon-nanotube composite nanofibers

Author name used in this publication: Shuncheng Lee2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Catalytic transfer hydrogenolysis of organosolv lignin using B-containing FeNi alloyed catalysts

© 2017 Elsevier B.V. In this work, FeB, NiB, and FeNiB nanomaterials were examined as catalysts for catalytic transfer hydrogenolysis (CTH) using supercritical ethanol (sc-EtOH) as the hydrogen donor and reaction solvent. The earth-abundant alloys were synthesized using simple aqueous chemical reductions and characterized using ICP-OES, XRD, and STEM-EDS. Using acetophenone to model the desired catalytic reactivity, FeNiB was identified as having superior reactivity (74% conversion) and selectivity for complete deoxygenation to ethylbenzene (84%) when compared to the monometallic materials. Given its high reactivity and selectivity for deoxygenation over ring saturation, FeNiB was screened as a lignin valorization catalyst. FeNiB mediates deoxygenation of aliphatic hydroxyl and carbonyls in organosolv lignin via CTH in sc-EtOH. A combination of gel permeation chromatography, GC/MS, and NMR spectroscopy was used to demonstrate the production of a slate of monomeric phenols with intact deoxygenated aliphatic side chains. In total, these results highlight the utility of CTH for the valorization of biorefinery-relevant lignin using an inexpensive, earth-abundant catalyst material and a green solvent system that can be directly derived from the polysaccharide fraction of lignocellulosic biomass

Identifying the Variety of Jovian X-Ray Auroral Structures: Tying the Morphology of X-Ray Emissions to Associated Magnetospheric Dynamics

We define the spatial clustering of X-rays within Jupiter's northern auroral regions by classifying their distributions into “X-ray auroral structures.” Using data from Chandra during Juno's main mission observations (24 May 2016 to 8 September 2019), we define five X-ray structures based on their ionospheric location and calculate the distribution of auroral photons. The morphology and ionospheric location of these structures allow us to explore the possibility of numerous X-ray auroral magnetospheric drivers. We compare these distributions to Hubble Space Telescope (HST) and Juno (Waves and MAG) data, and a 1D solar wind propagation model to infer the state of Jupiter's magnetosphere. Our results suggest that the five sub-classes of “X-ray structures” fall under two broad morphologies: fully polar and low latitude emissions. Visibility modeling of each structure suggests the non-uniformity of the photon distributions across the Chandra intervals are likely associated with the switching on/off of magnetospheric drivers as opposed to geometrical effects. The combination of ultraviolet (UV) and X-ray morphological structures is a powerful tool to elucidate the behavior of both electrons and ions and their link to solar wind/magnetospheric conditions in the absence of an upstream solar monitor. Although much work is still needed to progress the use of X-ray morphology as a diagnostic tool, we set the foundations for future studies to continue this vital research

A metabolite-derived protein modification integrates glycolysis with KEAP1-NRF2 signalling.

Mechanisms that integrate the metabolic state of a cell with regulatory pathways are necessary to maintain cellular homeostasis. Endogenous, intrinsically reactive metabolites can form functional, covalent modifications on proteins without the aid of enzymes1,2, and regulate cellular functions such as metabolism3-5 and transcription6. An important 'sensor' protein that captures specific metabolic information and transforms it into an appropriate response is KEAP1, which contains reactive cysteine residues that collectively act as an electrophile sensor tuned to respond to reactive species resulting from endogenous and xenobiotic molecules. Covalent modification of KEAP1 results in reduced ubiquitination and the accumulation of NRF27,8, which then initiates the transcription of cytoprotective genes at antioxidant-response element loci. Here we identify a small-molecule inhibitor of the glycolytic enzyme PGK1, and reveal a direct link between glycolysis and NRF2 signalling. Inhibition of PGK1 results in accumulation of the reactive metabolite methylglyoxal, which selectively modifies KEAP1 to form a methylimidazole crosslink between proximal cysteine and arginine residues (MICA). This posttranslational modification results in the dimerization of KEAP1, the accumulation of NRF2 and activation of the NRF2 transcriptional program. These results demonstrate the existence of direct inter-pathway communication between glycolysis and the KEAP1-NRF2 transcriptional axis, provide insight into the metabolic regulation of the cellular stress response, and suggest a therapeutic strategy for controlling the cytoprotective antioxidant response in several human diseases

A Versatile Route for the Synthesis of Nickel Oxide Nanostructures Without Organics at Low Temperature

Nickel oxide nanoparticles and nanoflowers have been synthesized by a soft reaction of nickel powder and water without organics at 100 °C. The mechanism for the formation of nanostructures is briefly described in accordance with decomposition of metal with water giving out hydrogen. The structure, morphology, and the crystalline phase of resulting nanostructures have been characterized by various techniques. Compared with other methods, the present method is simple, fast, economical, template-free, and without organics. In addition, the approach is nontoxic without producing hazardous waste and could be expanded to provide a general and convenient strategy for the synthesis of nanostructures to other functional nanomaterials

Domain wall brane in squared curvature gravity

We suggest a thick braneworld model in the squared curvature gravity theory. Despite the appearance of higher order derivatives, the localization of gravity and various bulk matter fields is shown to be possible. The existence of the normalizable gravitational zero mode indicates that our four-dimensional gravity is reproduced. In order to localize the chiral fermions on the brane, two types of coupling between the fermions and the brane forming scalar is introduced. The first coupling leads us to a Schr\"odinger equation with a volcano potential, and the other a P\"oschl-Teller potential. In both cases, the zero mode exists only for the left-hand fermions. Several massive KK states of the fermions can be trapped on the brane, either as resonant states or as bound states.Comment: 18 pages, 5 figures and 1 table, references added, improved version to be published in JHE

Colorectal Cancer Prognosis Following Obesity Surgery in a Population-Based Cohort Study

Background: Obesity surgery involves mechanical and physiological changes of the gastrointestinal tract that might promote colorectal cancer progression. Thus, we hypothesised that obesity surgery is associated with poorer prognosis in patients with colorectal cancer. Methods: This nationwide population-based cohort study included all patients with an obesity diagnosis who subsequently developed colorectal cancer in Sweden from 1980 to 2012. The exposure was obesity surgery, and the main and secondary outcomes were disease-specific mortality and all-cause mortality, respectively. Cox proportional hazard survival models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs), adjusted for sex, age, calendar year and education level. Results: The exposed and unexposed cohort included 131 obesity surgery and 1332 non-obesity surgery patients with colorectal cancer. There was a statistically significant increased rate of colorectal cancer deaths following obesity surgery (disease-specific HR 1.50, 95% CI 1.00–2.19). When analysed separately, the mortality rate was more than threefold increased in rectal cancer patients with prior obesity surgery (disease-specific HR 3.70, 95% CI 2.00–6.90), while no increased mortality rate was found in colon cancer patients (disease-specific HR 1.10, 85% CI 0.67–1.70). Conclusion: This population-based study among obese individuals found a poorer prognosis in colorectal cancer following obesity surgery, which was primarily driven by the higher mortality rate in rectal cancer

Proteomic analysis of the Plasmodium male gamete reveals the key role for glycolysis in flagellar motility.

BACKGROUND: Gametogenesis and fertilization play crucial roles in malaria transmission. While male gametes are thought to be amongst the simplest eukaryotic cells and are proven targets of transmission blocking immunity, little is known about their molecular organization. For example, the pathway of energy metabolism that power motility, a feature that facilitates gamete encounter and fertilization, is unknown. METHODS: Plasmodium berghei microgametes were purified and analysed by whole-cell proteomic analysis for the first time. Data are available via ProteomeXchange with identifier PXD001163. RESULTS: 615 proteins were recovered, they included all male gamete proteins described thus far. Amongst them were the 11 enzymes of the glycolytic pathway. The hexose transporter was localized to the gamete plasma membrane and it was shown that microgamete motility can be suppressed effectively by inhibitors of this transporter and of the glycolytic pathway. CONCLUSIONS: This study describes the first whole-cell proteomic analysis of the malaria male gamete. It identifies glycolysis as the likely exclusive source of energy for flagellar beat, and provides new insights in original features of Plasmodium flagellar organization