Room Temperature Photocatalytic Oxidation of Carbon Monoxide Over Pd/TiO2–SiO2 Catalysts

The photocatalytic oxidation of carbon monoxide over TiO₂–SiO₂ and Pd/TiO₂–SiO₂ catalysts was studied. The catalyst samples were synthesized by using sol–gel technique coupled with hydrothermal treatment and all samples were hydrothermally treated before calcination in air. The catalyst samples were characterized by XRD, BET and DRIFTS techniques. The photocatalytic activity of the samples was determined by using circulated batch photoreactor coupled with in line gas transmission FTIR cell charged with 2,000 ppm carbon monoxide in air initially over 0.5 g of catalyst sample under 33 W (254 nm) irradiation power. XRD and BET results confirmed the presence of anatase phase and the decrease on the crystallite size of TiO₂ with SiO₂ addition which yield higher surface area and better dispersion of TiO₂ over mesoporous SiO₂. DRIFTS results indicated the presence of surface hydroxyls coordinated to Ti⁴⁺ and Si–O–Ti sites. All samples containing 10–90 % TiO₂ over SiO₂ exhibited significant photo oxidation activity at room temperature. The photocatalytic oxidation rate of carbon monoxide is favored by SiO₂ addition due to high surface area, better dispersion of TiO₂ particles and higher surface defects. The addition of PdO improves the photocatalytic activity significantly and the synergy between the TiO₂ and PdO phases.     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

Correlative Light-Ion Microscopy for biological applications

Here we report a new technique, Correlative Light-Ion Microscopy (CLIM), to correlate SEM-like micrographs with fluorescence images. This technique presents significant advantages over conventional methods in enabling topographical and biochemical information to be correlated with nanoscale resolution without destroying the fluorescence signal. We demonstrate the utility of CLIM for a variety of investigations of cell substrate interactions validating its potential to become a routine procedure in biomedical research.     

Inverse propagation of uncertainties in finite element model updating through use of fuzzy arithmetic

A fuzzy finite element model updating (FFEMU) method is presented in this study for the damage detection problem. The uncertainty caused by the measurement noise in modal parameters is described by fuzzy numbers. Inverse analysis is formulated as a constrained optimization problem at each α-cut level. Membership functions of each updating parameter which correspond to reduction in bending stiffness of the finite elements is determined by minimizing an objective function using a hybrid version of genetic algorithms (GA) and particle swarm optimization method (PSO) which is very efficient in terms of accuracy and robustness. Practical evaluation of the approximate bounds of the interval modal parameters in FFEMU iterations is addressed. A probabilistic analysis is performed using Monte Carlo simulation (MCS) and the results are compared with presented FFEMU method. It is apparent from numerical simulations that the proposed method is well capable in finding the membership functions of the updating parameters within reasonable accuracy. It is also shown that the results obtained by FFEMU are in good agreement with the MCS results while FFEMU is not as computationally expensive as the MCS method. Nevertheless, the proposed FFEMU do not required derivatives of the objective function like existing methods except in the deterministic case.     

Damage Identification on the Tilff Bridge by Vibration Monitoring Using Optical Fiber Strain Sensors

Vibration testing is a well-known practice for damage identification of civil engineering structures. The real modal parameters of a structure can be determined from the data obtained by tests using system identification methods. By comparing these measured modal parameters with the modal parameters of a numerical model of the same structure in undamaged condition, damage detection, localization, and quantification is possible. This paper presents a real-life application of this technique to assess the structural health of the 50-year old bridge of Tilff, a prestressed three-cell box-girder concrete bridge with variable height. A complete ambient vibration survey comprising both vertical accelerations and axial strains has been carried out. The in situ use of optical fiber strain sensors for the direct measurement of modal strains is an original contribution of this work. It is a big step forward in the exploration of modal curvatures for damage identification because the accuracy in calculating the modal curvatures is substantially improved by directly measuring modal strains rather than deriving the modal curvatures from acceleration measurements. From the ambient vibrations, natural frequencies, damping factors, modal displacements and modal curvatures are extracted by the stochastic subspace identification method. These modal parameters are used for damage identification which is performed by the updating of a finite element model of the intact structure. The obtained results are then compared to the inspections performed on the bridge.     

A fast minimization technique for subspace fitting with arbitraryarray manifolds

A new technique for minimization of a multidimensional subspace fitting criterion is proposed. An approximation is made to the exact criterion function, giving an explicit least squares solution for location parameters. Ideas from alternating projections are employed for initialization. The new technique gives global convergence with a high probability, has a low computational cost, is applicable to general array manifolds, and provides simple solutions for many problems with intricate parameterization     

Effect of row space and irrigation on seed composition of Turkish sesame (Sesamum indicum L.)

The effect of row space (RS) and irrigation (IR) on total protein, total oil, and fatty acid composition of Harran-grown sesame seed was studied. Total oil content of sesame varied from 46.4 to 51.5%. The oil and protein contents were significantly different among treatments (P<0.01) in 1998 and 1999. IR affected oil content significantly (P<0.01) in both years, and RS had no significant effect. The protein content was significantly influenced by RS and IR at P<0.05 and P<0.01, respectively. RS 70 cm had the highest protein content followed by RS 60, 50, and 40 cm, respectively. IR every 24th day resulted in the highest level of protein, followed by 18th-, 12th-, and 6th-day irrigation, respectively. Correlation coefficients between protein and oil content were −0.34 in 1998 and −0.59 in 1999. RS (P<0.05) and IR (P<0.01) influenced oleic and linoleic acid contents significantly. Interactions of RS and IR were also found to be significant (P<0.05) over the oleic and linoleic acid levels.     

Occurrence of aflatoxins (B1, B2, G1, G2) in herbal tea consumed in Turkey

Aflatoxin contents in 12 types of herbal teas were determined by high performance liquid chromatography (HPLC) with fluorescence detector using immunoaffinity column clean-up. Forty eight samples were collected from four local herbal shops in Manisa, Turkey. Of the 48 samples analyzed, 43 were aflatoxin positive. The highest concentration of aflatoxin (34.18 µg/kg) was determined in a sample of camomile tea. The occurrence of AFB1, B2, G1 and G2 was found in samples at levels of 54, 29, 71 and 46 %, respectively. Aflatoxin B1, B2, G1 and G2 contamination levels varied from 0 to 14.2, 0 to 12.4, 0 to 13.5 and 0 to 28.7 µg/kg, respectively. Aflatoxin was not detected in five samples consisting of linseed, lime and fennel tea.