Society's increasing demand for transportation fuels has assured a viable future for the development of renewable fuels. Although fi rst-generation biofuels are dependent on starches, sugars and vegetable oils, the need to generate higher volumes of biofuels at lower cost has shifted the research focus to cellulosic ethanol. The utilization of lignocellulosics for the sustainable manufacturing of biofuels is critically dependent on the chemical constituents of the starting biomass and the desired fuel properties. This review examines the major chemical constituents of biomass and the recent advances in their conversion to biofuels, with a special emphasis on the forest residues and woody-energy crops to bioethanol.
Milled wood lignin samples from Loblolly pine stem wood, forest residue, and bark were isolated and characterized by quantitative (13)C and (31)P nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC) for molecular weight determination. Results from (13)C NMR show the stem wood and forest residue samples have similar functional group contents. However, the bark has fewer methoxyl groups, β-O-4 structures, dibenzodioxocin, and side chains than the other two lignins. The bark lignin has the highest amounts of p-hydroxyphenyl (h) and C-5 condensed lignin, stem wood has the lowest, and the residue lies between. (31)P NMR analysis indicates that bark lignin contains more C-5 substituted phenolics and fewer aliphatic hydroxyl groups than the lignin isolated from stem wood or residue. The molecular weight distribution analysis indicates the bark lignin has higher weight-average molecular weight (M(w)) and polydispersity index than the lignin recovered from stem wood or residue.
Bacterial
adhesion to stainless steel 316L (SS316L), which is an
alloy typically used in many medical devices and food processing equipment,
can cause serious infections along with substantial healthcare costs.
This work demonstrates that nanotextured SS316L surfaces produced
by electrochemical etching effectively inhibit bacterial adhesion
of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, but exhibit cytocompatibility and
no toxicity toward mammalian cells in vitro. Additionally, the electrochemical
surface modification on SS316L results in formation of superior passive
layer at the surface, improving corrosion resistance. The nanotextured
SS316L offers significant potential for medical applications based
on the surface structure-induced reduction of bacterial adhesion without
use of antibiotic or chemical modifications while providing cytocompatibility
and corrosion resistance in physiological conditions.
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