Publications by authors named "Frederik Romer"

Background: Adiposity is a major cause of morbidity and mortality in part due to effects on blood lipids. Nuclear magnetic resonance (NMR) spectroscopy provides direct information on >130 biomarkers mostly related to blood lipid particles.

Methods: Among 28,934 Mexican adults without chronic disease and not taking lipid-lowering therapy, we examine the cross-sectional relevance of body-mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), and hip circumference (HC) to NMR-measured metabolic biomarkers.

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Context: Chronic kidney disease (CKD) and diabetes are associated with dyslipidemia, metabolic abnormalities, and atherosclerotic risk. Nuclear magnetic resonance (NMR) spectroscopy provides much more detail on lipoproteins than traditional assays.

Methods: In about 38 000 participants from the Mexico City Prospective Study, aged 35 to 84 years and not using lipid-lowering medication, NMR spectroscopy quantified plasma concentrations of lipoprotein particles, their lipidic compositions, and other metabolic measures.

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Inorganic/organic sol-gel hybrids have nanoscale co-networks of organic and inorganic components that give them the unique potential of tailored mechanical properties and controlled biodegradation in tissue engineering applications. Here, silica/chitosan hybrid scaffolds with oriented structures were fabricated through the sol-gel method with a unidirectional freeze casting process. 3-Glycidoxypropyl trimethoxysilane (GPTMS) was used to obtain covalent inorganic/organic coupling.

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Proton conductivity in a series of mesoporous niobium and tantalum metal oxide (mX2 O5 ) composites of naphthalene sulfonic acid formaldehyde resin (NSF) that are resistant to moisture loss at temperatures greater than 50 °C is reported. The investigation focuses on the effect to proton conductivity by changing pore size and metal in the mesostructure of the mX2 O5 system and thus, a series of mX2 O5 -NSF composites were synthesized with C6 , C12 , and C18 templates. These were characterized by XRD, thermogravimetric analysis, nitrogen adsorption, and scanning TEM and then studied using impedance spectroscopy to establish proton conductivity values at various temperatures ranging from 25 to 150 °C.

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Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation.

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Chitosan has been explored as a potential component of biomaterials and scaffolds for many tissue engineering applications. Hybrid materials, where organic and inorganic networks interpenetrate at the molecular level, have been a particular focus of interest using 3-glycidoxypropyl trimethoxysilane (GPTMS) as a covalent crosslinker between the networks in a sol-gel process. GPTMS contains both an epoxide ring that can undergo a ring opening reaction with the primary amine of chitosan and a trimethoxysilane group that can co-condense with silica precursors to form a silica network.

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Bioactive glasses and inorganic/organic hybrids have great potential as biomedical implant materials. Sol-gel hybrids with interpenetrating networks of silica and biodegradable polymers can combine the bioactive properties of a glass with the toughness of a polymer. However, traditional calcium sources such as calcium nitrate and calcium chloride are unsuitable for hybrids.

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Solid state ¹³C-NMR spectra of pure tannin powders from four different sources--mimosa, quebracho, chestnut and tara--are readily distinguishable from each other, both in pure commercial powder form, and in leather which they have been used to tan. Groups of signals indicative of the source, and type (condensed vs. hydrolyzable) of tannin used in the manufacture are well resolved in the spectra of the finished leathers.

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