UV and VUV Photo-Oxidation of Fluoropolymer and Carbon Nanotube Surfaces

Three surface modification techniques: (1) atmospheric oxygen pressure using low-pressure Hg lamps, (2) low oxygen pressure with emission downstream from an Ar microwave plasma, and (3) high pressures of He in a rotating D.C. arc, that was designed to produce a spectral continuum from He excimers ( λ = 58 - 110 nm), were employed to photo-oxidize multiwalled carbon nanotube (MWNT) powder [1], single walled carbon nanotube (SWNT) paper [2], Teflon® polyfluorinated ethylene-propylene (FEP) [3] and Teflon® poly(tetrafluoroethylene-co-perfluropropyl vinyl ether) (PFA) [4]. Results from X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, FT-IR, Scanning Electron Microscopy (SEM) and Contact angle measurements of the oxidized surfaces are presented. Copper, that was sputter-coated onto the modified FEP and PFA, showed adhesion failure occurring within the modified materials (cohesive failure) and not at the Cu-FEP and -PFA interfaces. [1] B. Parekh, T. Debies, P. Knight, K. S. V. Santhanam and G. A. Takacs, Photo-oxidation of Multi walled Carbon Nanotubes , six page manuscript accepted for publication in: Proceedings of Fall 2005 National Meeting of the Materials Research Society; Symposium Q Degradation Processes in Nanostructured Materials, Boston MA (2006). [2] B. Parekh, T. Debies, C. M. Evans, B. J. Landi, R. P. Raffaelle and G. A. Takacs, Photo-oxidation of Single walled Carbon Nanotubes , six page manuscript accepted for publication in: Proceedings of Fall 2005 National Meeting of the Materials Research Society; Symposium Q Degradation Processes in Nanostructured Materials, Boston MA (2006). 11 [3] B. Parekh, A. Entenberg, T. Debies, and G. A. Takacs, Cohesive Failure of Sputtered Copper to Teflon^FEP Interface Modified with VUV Helium Excimer Radiation , presented at the Second International Symposium on Adhesion Aspects of Thin Films, Savannah, GA, Nov. 9-11, 2005. [4] B. Parekh, A. Entenberg, T. Debies, and G. A. Takacs, Interfacial Adhesion Improvement of Sputtered Cu to TeflonPFA Modified by VUV Helium Excimer Radiation , presented at the Rochester Section of American Chemical Society (ACS) in Rochester, NY, Sept. 29 - 30, 2005

Diurnal Differences in Risk of Cardiac Arrhythmias during Spontaneous Hypoglycemia in Young People with Type 1 Diabetes

OBJECTIVE Hypoglycemia may exert proarrhythmogenic effects on the heart via sympathoadrenal stimulation and hypokalemia. Hypoglycemia-induced cardiac dysrhythmias are linked to the “dead-in-bed syndrome,” a rare but devastating condition. We examined the effect of nocturnal and daytime clinical hypoglycemia on electrocardiogram (ECG) in young people with type 1 diabetes. RESEARCH DESIGN AND METHODS Thirty-seven individuals with type 1 diabetes underwent 96 h of simultaneous ambulatory ECG and blinded continuous interstitial glucose monitoring (CGM) while symptomatic hypoglycemia was recorded. Frequency of arrhythmias, heart rate variability, and cardiac repolarization were measured during hypoglycemia and compared with time-matched euglycemia during night and day. RESULTS A total of 2,395 h of simultaneous ECG and CGM recordings were obtained; 159 h were designated hypoglycemia and 1,355 h euglycemia. A median duration of nocturnal hypoglycemia of 60 min (interquartile range 40–135) was longer than daytime hypoglycemia of 44 min (30–70) (P = 0.020). Only 24.1% of nocturnal and 51.0% of daytime episodes were symptomatic. Bradycardia was more frequent during nocturnal hypoglycemia compared with matched euglycemia (incident rate ratio [IRR] 6.44 [95% CI 6.26, 6.63], P < 0.001). During daytime hypoglycemia, bradycardia was less frequent (IRR 0.023 [95% CI 0.002, 0.26], P = 0.002) and atrial ectopics more frequent (IRR 2.29 [95% CI 1.19, 4.39], P = 0.013). Prolonged QTc, T-peak to T-end interval duration, and decreased T-wave symmetry were detected during nocturnal and daytime hypoglycemia. CONCLUSIONS Asymptomatic hypoglycemia was common. We identified differences in arrhythmic risk and cardiac repolarization during nocturnal versus daytime hypoglycemia in young adults with type 1 diabetes. Our data provide further evidence that hypoglycemia is proarrhythmogenic

A(a)LS: Ammonia-induced amyotrophic lateral sclerosis [version 1; referees: 2 approved]

Amyotrophic lateral sclerosis (ALS) is a dreadful, devastating and incurable motor neuron disease. Aetiologically, it is a multigenic, multifactorial and multiorgan disease. Despite intense research, ALS pathology remains unexplained. Following extensive literature review, this paper posits a new integrative explanation. This framework proposes that ammonia neurotoxicity is a main player in ALS pathogenesis. According to this explanation, a combination of impaired ammonia removal— mainly because of impaired hepatic urea cycle dysfunction—and increased ammoniagenesis— mainly because of impaired glycolytic metabolism in fast twitch skeletal muscle—causes chronic hyperammonia in ALS. In the absence of neuroprotective calcium binding proteins (calbindin, calreticulin and parvalbumin), elevated ammonia—a neurotoxin—damages motor neurons. Ammonia-induced motor neuron damage occurs through multiple mechanisms such as macroautophagy-endolysosomal impairment, endoplasmic reticulum (ER) stress, CDK5 activation, oxidative/nitrosative stress, neuronal hyperexcitability and neuroinflammation. Furthermore, the regional pattern of calcium binding proteins’ loss, owing to either ER stress and/or impaired oxidative metabolism, determines clinical variability of ALS. Most importantly, this new framework can be generalised to explain other neurodegenerative disorders such as Huntington’s disease and Parkinsonism

Assessment of gut microbial β-glucuronidase and β-glucosidase activity in women with polycystic ovary syndrome

Abstract PCOS is a prevalent endocrine disorder among women of reproductive age, characterized by hormonal imbalances and metabolic disturbances. This study explores the correlation between gut microbial β-glucuronidase and β-glucosidase and PCOS, focusing on their association with hormone levels and other clinical parameters. In this case-control study, fecal samples were collected from women of reproductive age, both with and without PCOS. The analysis of gut β-glucuronidase and β-glucosidase enzymes was conducted with the other clinical parameters, including body mass index, hormone levels, and hirsutism. These factors were then subjected to correlation analysis. PCOS women showed significantly higher levels of β-glucuronidase activity with a statistically significant P-value (0.05 ± 0.1 vs. 0.04 ± 0.1; P = 0.006) as well as β-glucosidase activity (0.13 ± 0.08 vs. 0.09 ± 0.05; P = 0.06) compared to the controls. This study also revealed intriguing connections between the selected enzymes and hormone levels, particularly testosterone and estradiol. Gut microbial enzymes β-glucuronidase and β-glucosidase may be used as biomarkers for early detection and monitoring of PCOS in women with metabolic challenges. It could lead to improved diagnostic tools and treatment options

Flexible organic photovoltaics from zinc oxide nanowires grown on transparent and conducting single walled carbon nanotube thin films

The fabrication of flexible organic photovoltaics (OPVs) which utilize transparent and conducting single walled carbon nanotube (SWNT) thin films as current collecting electrodes on plastic substrates in zinc oxide nanowire (ZnO NW)/poly(3-hexylthiophene) (P3HT) bulk heterojunction photovoltaic devices is reported. The bulk heterojunctions for exciton dissociation are created by directly growing ZnO nanowires from solution on the SWNT electrodes and spin coating the P3HT polymer. A maximum OPV power conversion efficiency of similar to 0.6% was achieved. Our results indicate that nanotube-nanowire hybrids fabricated via solution based methods are promising for optoelectronic and energy harvesting devices

Inhibition of human papilloma virus E2 DNA binding protein by covalently linked polyamides

Polyamides are a class of heterocyclic small molecules with the potential of controlling gene expression by binding to the minor groove of DNA in a sequence-specific manner. To evaluate the feasibility of this class of compounds as antiviral therapeutics, molecules were designed to essential sequence elements occurring numerous times in the HPV genome. This sequence element is bound by a virus-encoded transcription and replication factor E2, which binds to a 12 bp recognition site as a homodimeric protein. Here, we take advantage of polyamide:DNA and E2:DNA co-crystal structural information and advances in polyamide synthetic chemistry to design tandem hairpin polyamides that are capable of displacing the major groove-binding E2 homodimer from its DNA binding site. The binding of tandem hairpin polyamides and the E2 DNA binding protein to the DNA site is mutually exclusive even though the two ligands occupy opposite faces of the DNA double helix. We show with circular permutation studies that the tandem hairpin polyamide prevents the intrinsic bending of the E2 DNA site important for binding of the protein. Taken together, these results illustrate the feasibility of inhibiting the binding of homodimeric, major groove-binding transcription factors by altering the local DNA geometry using minor groove-binding tandem hairpin polyamides