In this work, we used N-hydroxyacetanilide (NHA) in combination with laccase for the first time to bleach eucalypt pulp and found it to be a very promising, advantageous alternative to 1-hydroxybenzotriazole (HBT) as mediator. Thus, NHA is efficiently oxidized by laccase to a radical that absorbs light at 350 nm. Also. NHA is a better substrate for laccase than is HBT. An innovative result is that the enzyme is inactivated selleck products to a similar extent by both mediators under the typical treatment conditions of the bleaching step (L). This adverse effect, however, is strongly reduced in the presence of pulp. Moreover, the laccase-NHA system is as efficient as the laccase-HBT
system in reducing the kappa number of eucalyptus pulp. Using a xylanase pretreatment or unbleached pulp boosts kappa number reduction and bleaching with
the laccase-mediator system. Based on the results of cyclic voltammetry tests, NHA has a slightly lower redox potential TH-302 than HBT, which further supports use of the former; also, unlike HBT, NHA is oxidized in a reversible, pH-dependent manner. Interestingly, the laccase-NHA system provides more efficient bleaching of eucalyptus pulp at pH 5 than it does at pH 4. (C) 2010 Elsevier B.V. All rights reserved.”
“Study Design. Biomechanical study of a posterior reduction and stabilization of a Jefferson C1 burst fracture using mono-versus poly-axial screws.
Objective. To introduce a new motion-preserving surgical method for reduction and stabilization of an isolated Jefferson fracture and investigate its effectiveness with a biomechanical study.
Summary of Background Data. Jefferson fractures have been treated conservatively by immobilization, traction, or surgical fusion of C1-C2 or occiput-to-C2.
Conservative treatment usually requires prolonged buy CP-868596 immobilization with a cumbersome external brace. Surgical fusion, however, eliminates the important range of motion (ROM) of C1-C2 or occiput-to-C2.
Methods. Six occiput-to-C3 cadaveric specimens were tested biomechanically. After creating a Jefferson fracture, bilateral atlantal lateral mass screws were inserted on the posterior aspect of each specimen. The screws were connected with a rod and nuts. The posterior distance and the anterior distance were measured to evaluate the magnitude of reduction and resistance to loading after instrumentation placement. Measurements were performed after mono-and poly-axial head screw insertion, and then using destabilized specimens. ROM was also measured after applying a 1.5 Nm moment to six cardinal directions before the trauma, after mono-and poly-axial screw fixation and in destabilized specimens.
Results. The posterior distances after mono-axial and poly-axial screw fixations were significantly reduced compared with that of the destabilized atlas. In the specimens reduced with mono-and poly axial screws, the averages were 50.2 and 50.2 mm, and in the destabilized specimen, the average was 54 mm.