Beyond What Meets the Eye: Imaging and Imagining Wood Mechanical–Structural Properties

Abstract: Wood presents a hierarchical structure, containing features at all length scales: from the tracheids or vessels that make up its cellular structure, through to the microfibrils within the cell walls, down to the molecular architecture of the cellulose, lignin, and hemicelluloses that comprise its chemical makeup. This structure renders it with high mechanical (e.g., modulus and strength) and interesting physical (e.g., optical) properties. A better understanding of this structure, and how it plays a role in governing mechanical and other physical parameters, will help to better exploit this sustainable resource. Here, recent developments on the use of advanced imaging techniques for studying the structural properties of wood in relation to its mechanical properties are explored. The focus is on synchrotron nuclear magnetic resonance spectroscopy, X‐ray diffraction, X‐ray tomographical imaging, Raman and infrared spectroscopies, confocal microscopy, electron microscopy, and atomic force microscopy. Critical discussion on the role of imaging techniques and how fields are developing rapidly to incorporate both spatial and temporal ranges of analysis is presented

Pars plana vitrectomy in ocular Behçet's disease

PubMedID: 12678399Purpose: To evaluate the results of pars plana vitrectomy in Behçet patients with dense vitreous opacities, and its effect on intraocular inflammatory episodes and visual prognosis. Methods: The study group consisted of nine patients (one eye in eight patients, both eyes in one) with Behçet's disease who underwent pars plana vitrectomy because of dense vitreous opacification. The indications for vitrectomy, the effect of vitrectomy on the frequency of severe intraocular inflammatory episodes, and visual prognosis were investigated in these patients. All the patients were male, and their ages ranged between 28-45 years. Combined lensectomy was performed on those with complicated cataracts. The postoperative follow-up was between 12-66 months. Results: In all of the patients preoperative visual acuity was hand motions. Postoperatively there was no change in vision in five eyes, however visual acuity improved in five eyes, between counting fingers and 0.4. None of the patients showed any severe postoperative intraocular inflammatory episodes, and phthisis did not develop in any of the patients. Conclusion: In this study, pars plana vitrectomy was found to have a beneficial effect on the prognosis of vision. There was also a decrease in the frequency of severe intraocular inflammatory episodes n patients with Behçet's disease with severe vitreous opacities, who did not respond to maximum medical treatment. However, further studies on larger groups should be performed in order to confirm the findings of this study

Effects of heat Post-Treatment on dimensional stability and water absorption behaviours of mechanically densified uludağ fir and black poplar woods

One of the most persistent problems with mechanically densified wood is its inherent dimensional instability. The effects of heat post-treatment on the changes in spring-back (SB), compression ratio recovery (CRR), thickness swelling (TS), and water absorption (WA) of newly-tested Uludağ fir (Abies bornmuelleriana Mattf.) and black poplar (Populus nigra L.) wood samples that had been thermo-mechanically densified were investigated. Samples were densified with compression ratios of 25% and 50% with temperatures of 100 and 140 °C, respectively. Then, the heat post-treatment was applied to the samples at 185 and 212 °C for 2 h. For the two newly-tested wood types, results of the preliminary study show that SB and TS were higher at a 50% compression ratio compared with 25%. Regarding densification temperature, TS was lower in samples densified at 140 °C, while SB was higher. WA values were lower in compressed samples (50%) at high rates. The effect of the densification temperature on WA was insignificant. Heat post-treatment had a considerable effect on the dimensional stability and hygroscopicity of the densified Uludağ fir and black poplar samples. With an increase in heat treatment temperature, the dimensional stability increased, while the hygroscopicity of densified samples decreased. As a result of heat post-treatment applied at 212 °C, SB, CRR, TS, and WA decreased by 88%, 85%, 79%, and 53%, respectively

The Impact of Magnesium on Isometric Twitch Parameters and Resting Membrane Potential of the Skeletal Muscle in Diabetic Rats

PubMedID: 23080019To present the relationship between oral magnesium supplementation, blood glucose, and changes in isometric twitch parameters, resting membrane potential (RMP), in the gastrocnemius muscle in diabetic rats. Sixty rats were used in this study. The rats were divided into four groups: control (drinking tap water, Group I, n = 15), control with treated with magnesium sulfate (10 g/L) (Group II, n = 15), diabetic (Group III, n = 15), and diabetic with treated with magnesium sulfate (10 g/L) (Group IV, n = 15). In Group II and IV, the level of plasma magnesium was increased comparing to those of the control group (p < 0. 05). Isometric twitch tensions were decreased significantly in the Group III, but Group IV isometric twitch tensions were increased significantly. Group IV RMP values were close to the Group I. Hyperglycemia decreases gastrocnemius muscle isometric twitch tension and increases RMP in diabetic rats. Magnesium treatment can prevent these diabetic complications. © 2012 Springer Science+Business Media New York

Silver anode-induced phenotypical changes in bacteria

Background: It has been definitely proven that the silver ions emitted from a silver electrode are highly bactericidal. When silver electrodes are embedded in a culture medium, generally, the area immediately around the anode is found to be sterile but a certain bacterial population remains outside of this inhibition zone. Methods: In the following study, four randomly chosen bacterial samples were incubated into Endo agar by the presence of a silver anode. Inhibition zones occurred and bacterial specimens were taken from area which is outside of the boundary of inhibition zone and analyzed using standard physiological and biochemical tests. Results: It was found that the bacteria remaining in this area were changed phenotypically. They lost their genus-specific characteristics and were identified as different strains. These phenotypical deviations were interpreted from a taxometric perspective by a computer program. The changes were between 10-32 Operational Taxonomic Units. Conclusion: These specimens were then recultured on Endo agar. They continued to change their biochemical identity with the exception of two samples and all of them became quinolone-sensitive even if they had been previously resistant. Electrically released silver ion therapy seems to be just as effective method at least for bacterial infections

The effects of magnetic field on the biomechanics parameters of soleus and extensor digitorum longus muscles in rats with streptozotocin-induced diabetes

PubMedID: 18715203Background: The aim of this study was to determine the effects of the magnetic field (MF) on the isometric contractile characteristics of the soleus and extensor digitorum longus (EDL) muscles in rats both with and without diabetes. Methods: Biomechanical parameters were recorded in vitro from Wistar rats without diabetes (Group I, n = 20), rats without diabetes exposed to MF (Group II, n = 20), rats with streptozotocin-induced diabetes (Group III, n = 20), and rats with diabetes exposed to MF (Group IV, n = 20). Muscle strips were taken from the distal tendon soleus and EDL muscles of rats killed by decapitation. The muscles were hung in organ baths containing Krebs solution (pH 7.4) with a gas mixture of 95% O2 and 5% CO2. Then the muscles were triggered to direct supramaximal stimulation with 0.05 Hz frequency square pulses for periods of 0.5 ms to obtain control values. The contractile parameters were also determined for two muscles of the four groups. Later, the tension-frequency relationship was determined by applying stimulating pulses of 10, 20, 50, and 100 Hz to the muscles. Results: Diabetes caused a certain amount of decrease in the contractile force of the two muscles compared with that of control values. However, MF increased the contractile force of the two muscles in rats both with and without diabetes. The isometric contraction forces obtained by different stimulating frequencies showed a significant linear increase in the tetanic contraction (P &lt; 0.05). Diabetes increased the contraction time of the isometric twitch tension compared with that of the control group with a statistically significant difference (P &lt; 0.05). MF decreased the contraction time of the two muscles of rats without diabetes (P &lt; 0.05) but increased that of rats with diabetes (P &gt; 0.05). Conclusion: In our study, these results suggest that MF exposure regulates the isometric contractile characteristics of the soleus and EDL muscles of rats with diabetes, positively. © 2008 Mary Ann Liebert, Inc