V2O5 aerogel as a versatile host for metal ions Tang, Paul E.; Sakamoto, Jeff S.; Baudrin, Emmanuel ...
Journal of non-crystalline solids,
12/2004, Letnik:
350, Številka:
Complete
Journal Article, Conference Proceeding
Recenzirano
Vanadium pentoxide aerogels have the ability to electrochemically insert a wide variety of metal ions. This paper describes the reversible insertion of Na+, K+, Mg2+, and Ba2+: these ions represent a ...progression of ion size and charge. A critical factor in their insertion is the role of surface morphology, as it appears that divalent insertion, in particular, is associated with the high surface area of the aerogel. In nearly all cases, the amount of reversible insertion greatly exceeds values reported for other materials. Moreover, this is the first report of reversible electrochemical insertion of Ba2+ in solids. The measurements indicate a general trend of lower specific energy density as charge increases.
In order to understand the salt-tolerance mechanism of alkali grass (Puccinellia tenuiflora) compared with wheat (Triticum aestivum L.), K+ and Na+ in roots and shoots in response to salt treatments ...were examined with ion element analysis and X-ray microanalysis. Both the rapid K+ and Na+ influx in response to different NaCl and KCl treatments, and the accumulation of K+ and Na+ as the plants acclimated to long-term stress were studied in culture- solution experiments. A higher K+ uptake under normal and saline conditions was evident in alkali grass compared with that in wheat, and electrophysiological analyses indicated that the different uptake probably resulted from the higher K+/Na+ selectivity of the plasma membrane. When external K+ was high, K+ uptake and transport from roots to shoots were inhibited by exogenous Cs+, while TEA (tetraethylammonium) only inhibited K+ transport from the root to the shoot. K+ uptake was not influenced by Cs+ when plants were K+ starved. It was shown by X-ray microanalysis that high K+ and low Na+ existed in the endodermal cells of alkali grass roots, suggesting this to be the tissue where Cs+ inhibition occurs. These results suggest that the K+/Na+ selectivity of potassium channels and the existence of an apoplastic barrier, the Casparian bands of the endodermis, lead to the lateral gradient of K+ and Na+ across root tissue, resulting not only in high levels of K+ in the shoot but also a large Na+ gradient between the root and the shoot.
Epithelial injury, alternative macrophage accumulation, and fibroproliferation coexist in the lungs of patients with idiopathic pulmonary fibrosis (IPF). Chitinase 3-like 1 (CHI3L1) is a prototypic ...chitinase-like protein that has been retained over species and evolutionary time. However, the regulation of CHI3L1 in IPF and its ability to regulate injury and/or fibroproliferative repair have not been fully defined. We demonstrated that CHI3L1 levels were elevated in patients with IPF. High levels of CHI3L1 are associated with progression--as defined by lung transplantation or death--and with scavenger receptor-expressing circulating monocytes in an ambulatory IPF population. In preterminal acute exacerbations of IPF, CHI3L1 levels were reduced and associated with increased levels of apoptosis. We also demonstrated that in bleomycin-treated mice, CHI3L1 expression was acutely and transiently decreased during the injury phase and returned toward and eventually exceeded baseline levels during the fibrotic phase. In this model, CHI3L1 played a protective role in injury by ameliorating inflammation and cell death, and a profibrotic role in the repair phase by augmenting alternative macrophage activation, fibroblast proliferation, and matrix deposition. Using three-dimensional culture system of a human fibroblast cell line, we found that CHI3L1 is sufficient to induce low grade myofibroblast transformation. In combination, these studies demonstrate that CHI3L1 is stimulated in IPF, where it represents an attempt to diminish injury and induce repair. They also demonstrate that high levels of CHI3L1 are associated with disease progression in ambulatory patients and that a failure of the CHI3L1 antiapoptotic response might contribute to preterminal disease exacerbations.
Pseudomembranous colitis is an inflammatory condition of the colon characterized by elevated yellow-white plaques that coalesce to form pseudomembranes on the mucosa. Patients with the condition ...commonly present with abdominal pain, diarrhea, fever, and leukocytosis. Because pseudomembranous colitis is often associated with
C. difficile
infection, stool testing and empiric antibiotic treatment should be initiated when suspected. When results of
C. difficile
testing are negative and symptoms persist despite escalating empiric treatment, early gastroenterology consultation and lower endoscopy would be the next step in the appropriate clinical setting. If pseudomembranous colitis is confirmed endoscopically, colonic biopsies should be obtained, as histology can offer helpful clues to the underlying diagnosis. The less common non-
C. difficile
causes of pseudomembranous colitis should be entertained, as a number of etiologies can result in this condition. Examples include Behcet’s disease, collagenous colitis, inflammatory bowel disease, ischemic colitis, other infections organisms (e.g. bacteria, parasites, viruses), and a handful of drugs and toxins. Pinpointing the correct underlying etiology would better direct patient care and disease management. Surgical specialists would be most helpful in colonic perforation, gangrenous colon, or severe disease.
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