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

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

Polythiophene–Clay Composite Solid-Phase Microextraction Fiber: Preparation, Characterization, and Application to the Determination of Methanol in Biodiesel

ABSTRACT: A novel polymer-clay composite solid phase microextraction fiber is reported for the adsorption of methanol in biodiesel with subsequent determination by gas chromatography coupled with a flame ionization detector. The fiber was fabricated using a stainless steel wire that was subjected to electropolymerization in 0.1 mol NaClO4 containing thiophene and montmorillonite clay dispersed in acetonitrile. Electrochemical deposition was maintained by cycling the potential from -0.2 to +2.2 V at a scan rate of 50 mV/sec. Examination of the surface by scanning electron microscopy revealed that the fiber had a porous surface suitable for the adsorption of volatile analytes. The properties of the fiber were investigated by thermogravimetric analysis and infrared spectroscopy that showed that the clay was inserted in the structure. The fiber was exposed to methanol in biodiesel. The adsorption time, adsorption temperature, and desorption temperature were optimized. Under the optimized conditions, the linear dynamic range for methanol extended from 0.029 to 0.24% (m/m) with a limit of detection of 0.009% (m/m). The method was employed for the analysis of biodiesel and the results were validated with a standard EN 14110 method. © 2016, Copyright © Taylor & Francis Group, LLC

Repetitive 50 Hz pulsed electromagnetic field ameliorates the diabetes-induced impairments in the relaxation response of rat thoracic aorta rings

PubMedID: 19579070Purpose: To evaluate the characteristic features of mechanical responses and the membrane potential changes induced by repetitive pulsed electromagnetic field (PEMF, 50 Hz, 5 mT) in thoracic aorta rings obtained from streptozotocin-induced diabetic and healthy control rats to determine if PEMF could ameliorate problems associated with diabetes. Methods: Sixty male Wistar rats weighing 250-290 g were randomly divided into two experimental groups, each containing 30 animals. Streptozotocin was given via tail vein to produce diabetes mellitus (DM) in the first group rats. The second group rats were treated only with % 0.9 saline and considered as non-DM group. Both groups were also divided into two subgroups as DM + PEMF, DM + sham, PEMF and sham, each containing 15 animals. Although the DM + PEMF and PEMF groups were treated, the DM + sham and sham groups were not treated with PEMF. The PEMF treatment occurred four times daily for 30 min at 15-min intervals repeated daily for 30 days. Thoracic aorta rings from both DM and non-DM rats exposed to PEMF were evaluated for contraction and relaxation responses and membrane potential changes in the presence or absence of chemical agents that were selected to test various modes of action. Results: Relaxation response of thoracic aorta rings was significantly reduced in DM than non-DM group. PEMF treatment significantly increased the relaxation response of the diabetic rings to acetylcholine, and reduced the concentration response to phenylephrine. Resting membrane potential was significantly higher in DM than in non-DM group. Inhibitors of nitric oxide (NO), both nitro-L-arginine (L-NO-ARG) and L-NO-ARG + indometacin combination, produced a significant transient hyperpolarisation in all groups. Inhibitors of potassium channel activity, charybdotoxin or apamine, produced a membrane depolarisation. However, PEMF did not induce any significant effect on the membrane potential in DM group. Conclusions: Diabetes reduced the relaxation response of thoracic aorta rings. It also affected the membrane potentials of the rings. Treatment with PEMF ameliorated the diabetes-induced impairments in the relaxation response of these rings. © 2009 Informa Healthcare USA, Inc

Biosorption of Cu(II) and Pb(II) ions from aqueous solution by natural spider silk

WOS: 000295345700012PubMed ID: 21803575Aside from its excellent mechanical properties, spider silk (SS) would offer an active surface for heavy metal interaction due to its rich protein structure. The present study describes the potential use of natural (SS) as a sorbent of heavy metals from aqueous solutions. Single and multi-species biosorption experiments of heavy metals by natural SS were conducted using batch and column experiments. The biosorption kinetics, in general, was found to follow the second-order rate expression, and the experimental equilibrium biosorption data fitted reasonably well to Freundlich isotherm. From the Freundlich isotherm, the biosorption capacities of Cu(II) and Pb(II) ions onto SS were found as 0.20 and 0.007 mmol g(-1), respectively. The results showed a decrease in the extent of metal ion uptake with lowering the pH. (C) 2011 Elsevier Ltd. All rights reserved.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Ege University Scientific ResearchEge University [2004 FEN 051]This study was supported by TUBITAK and Ege University Scientific Research Project (2004 FEN 051). Authors would like to thank Prof. Dr. Mehmet Yurekli for proof reading and Dr. Ebru Ayan Mavioglu for her valuable helps in measuring zeta potentials

Head space voltammetry: A novel voltammetric method for volatile organics and a case study for phenol

PubMed ID: 22939125Present paper describes the results of a novel method which combines the Head space (HS) preconcentration of the analyte on the electrode prior to the voltammetric analysis. Thereafter, the method was called HS-Voltammetry. The performance of the method was tested upon using an electroactive and volatile molecule, phenol molecule, which gives an oxidation peak at conventional electrodes. In this study, a glassy carbon electrode was modified with polypyrrole by electropolymerization and then, the electrode was placed over the solution in a sealed vial heated gently on a hotplate with a stirrer for phenol determination. By controlling the thickness of the polymeric coating and optimizing preconcentration parameters such as vial pH and temperature, stirring rate and exposure time, a very consistent (5.2% at 5.0×10-7 M) fraction of the analyte can be extracted during a predetermined time. The oxidation peak current at 0.8 V depended linearly on the phenol concentration over a wide range (3 orders of magnitude). The detection limit was estimated as 7.0×10-8 M at 60 °C (S/N=3) which is well below the limit set by the European Community for phenols in wastewaters (ca. 5×10 -6 M). The effect of other phenolic compounds was also examined and it was shown that head space preconcentration eliminated the interference of non-volatile phenolic acids studied. For volatile phenolic compounds, the selectivity can be maintained in cases when isolated peaks are obtained for each component. The proposed method has been applied successfully for the determination of phenol in artificial wastewater and recovery percentage was calculated as 93%. © 2012 Elsevier B.V. All rights reserved

The effect of paracetamol on postoperative nausea and vomiting during the first 24 h after strabismus surgery: a prospective, randomised, double-blind study

WOS: 000296721600005PubMed: 21986980Context Strabismus surgery is one of the most common ophthalmic surgical procedures in children and is associated with significant postoperative nausea and vomiting (PONV). Objective We evaluated the effect of intravenous paracetamol on PONV in children after strabismus surgery. Design Prospective, placebo-controlled, randomised double-blind study. Setting University hospital. Patients Ninety children, between 2 and 14 years scheduled for strabismus surgery, were recruited. Eighty-six completed the study. Interventions After induction of anaesthesia, intravenous dexamethasone 0.1 mg kg(-1) was administered to all. The patients were enrolled to receive either intravenous physiological saline (group S) or paracetamol 15 mg kg(-1) (group P). Main outcome measure Incidence of PONV in the first 24 h postoperatively. Results General and clinical characteristics of the children were similar in both groups. PONV during the first 24 h was significantly higher in group S in comparison with group P (group S vs. group P, 33 vs. 14.6%, respectively, P = 0.038 for nausea; 24.4 vs. 7.3%, respectively, P = 0.030 for vomiting). The number of analgesic administrations during the first 24 h was higher in group S compared with group P (1.31 +/- 0.85 and 0.73 +/- 0.6, respectively, P = 0.001). The repeat number of postoperative analgesic administrations was significantly different between groups during the first 24 h (P = 0.005), but during 24-48 h was not significant. Conclusion Intraoperative administration of intravenous paracetamol decreases the incidence of PONV during the first 24 h in children after strabismus surgery. Eur J Anaesthesiol 2011;28:836-841Baskent UniversityBaskent University [09/257]This study was supported by Baskent University Research Fund (project number 09/257)