Buckling lengths of irregular frame columns

In several design codes and specifications, simplified formulae and diagrams are given for determining the buckling lengths of frame columns. It is shown that these formulae may yield rather erroneous results, especially for irregular frames. This is due to the fact that the code formulae utilise only local stiffness distributions. In this paper, a simplified procedure for determining approximate values for the buckling loads of both regular and irregular frames is developed. The procedure utilises lateral load analysis of frames and yields errors on the order of 5%, which may be considered suitable for design purposes. The proposed procedure is applied to several numerical examples and it is shown that all the errors are in the acceptable range and on the safe side.     

The effect of additives on the oxidation stability of biodiesel

In the present study, it was aimed to examine the degradation of biodiesel and the changes that occur in the cold flow characteristics of biodiesel obtained from safflower oil as a result of the modification of the production process steps that leads to a state in which the process is not realized completely despite the addition of antioxidant additives that stabilize the cold flow characteristics of the fuel and the effects of the modification of the production process steps on fuel characteristics. The study is focused on the modification of the production process. Some samples showed very rapid decomposition in the first 3 hours but the rest took nearly 3 days to reach 200 microsiemens. But then the derivative this value due to the rate of oxidation 0.04 h showed.     

2-D DOA estimation in case of unknown mutual coupling for multipath signals

In this paper, two dimensional (2-D) direction-of-arrival (DOA) estimation problem in case of unknown mutual coupling and multipath signals is investigated for antenna arrays. A new technique is proposed which uses a special array structure consisting of parallel uniform linear array (PULA). PULA structure is complemented with auxiliary antennas in order to have a structured mutual coupling matrix (MCM). MCM has a symmetric banded Toeplitz structure which allows the application of the ESPRIT algorithm for 2-D paired DOA estimation. The advantage of the PULA structure is exploited by dividing it into overlapping linear sub-arrays (triplets) and spatial smoothing is employed to mitigate multipath signals. Closed form expressions are presented for search-free, paired and unambiguous 2-D DOA estimation. Two algorithms PULA-1 and PULA-2 are proposed to effectively solve the problem. Several simulations are done and the accuracy of the proposed solution is shown.     

Effect of Al2O3 Additions on the Thermal Expansion Behavior of a Li2O-ZnO-SiO2 Glass-Ceramic

The effect of Al₂O₃ substitution on the thermal expansion behavior of a Li₂O-ZnO-SiO₂ glass-ceramic was investigated using differential thermal analysis, X-ray diffractometry, and dilatometry. The coefficient of thermal expansion of the original Al₂O₃-free glass-ceramic measured between 20° and 900°C decreased from 12.4 × 10^-6°C^-1 to 6.3 × 10^-6°C^-1 with Al₂O₃ substitution for ZnO up to 11 wt%. The results were correlated to the changes in the phase assemblage with Al₂O₃ addition.     

First-Principles Calculations on Structure,Elastic and Thermodynamic Properties of Al2X （X=Sc,Y） under Pressure

To understand deeply the structural,elastic and thermodynamic characteristics of Al 2 X (X= Sc,Y) compounds in C15 type (space number 227) Cu 2 Mg structure,we have performed ab-initio density functional theory within the local density approximation (LDA) and the generalized gradient approximation (GGA).The thermodynamic properties of the considered structures are obtained through the quasi-harmonic Debye model.We have presented the results on the basic physical parameters,such as the lattice constant,bulk modulus,pressure derivative of bulk modulus,second-order elastic constants,Zener anisotropy factor,Poisson s ratio,Young s modulus,and isotropic shear modulus.In order to gain further information,the pressure-and temperature-dependent behaviour of the volume,bulk modulus,thermal expansion coefficient,heat capacity,entropy,Debye temperature and Gru¨neisen parameter were also evaluated over a pressure range of 0-20 GPa for Al 2 Sc and 0-17 GPa for Al 2 Y compound and a wide temperature range of 0-2000 K for both compounds.The obtained results were compared with the other reported values.     

The first catalytic hydrolysis of ethylenediamine bisborane with hydrogel-supported metallic nanoparticles

Ethylene diamine bisborane (EDB) was synthesized in a single step as the hydrogen storage material. The synthesized compound was firstly used in the literature for the production of hydrogen gas by catalytic hydrolysis reaction. Cu, Co and Ni nanoparticles with average sizes of 75–150 nm formed in p(acrylicacid-co-vinylimidazole) hydrogel network structures were used as catalysts for the hydrolysis reaction. The effect of the parameters such as catalyst type, EDB concentration, catalyst concentration, temperature and solvent environment on the catalytic hydrolysis reaction of EDB was investigated. In the activity tests for the catalyst, it was determined that the catalyst had a loss of only 15% in activity even at the end of 5 cycles. The activation energies of hydrolysis reaction were calculated as 39.42 kJmol^–1, 44.77 kJmol^–1 and 47.48 kJmol^–1 for Cu, Co and Ni hydrogel composite catalyst, respectively.     

Degradation kinetics of β-carotene in carrot slices during convective drying

The β-carotene degradation was investigated in carrot (Daucus carota L. cv Nantes) slices during convective drying at three temperatures (45, 55, and 65°C) at an airflow rate of 0.2 m s^–1. Degradation kinetics of β-carotene in carrot slices during convective drying followed a first-order reaction. Drying temperature showed a significant effect on the degradation of β-carotene in carrot slices. The range of the reaction rate constants for β-carotene loses were 0.23 ± 0.08 –0.48 ± 0.04 h^–1. The activation energy of β-carotene degradation is found 33.33 ± 0.05 kJ mol^–1. Half-life time was calculated as 3.02 ± 0.04 h at 45°C, which dropped to 1.43 ± 0.03 h at 65°C.     

An adaptable luminescence resonance energy transfer assay for measuring and screening protein-protein interactions and their inhibition

Protein-protein interactions (PPIs) are central to biological processes and represent an important class of therapeutic targets. Here we show that the interaction between FK506-binding protein 12 fused to green fluorescent protein (GFP-FKBP) and the rapamycin-binding domain of mTor fused to Escherichia coli dihydrofolate reductase (FRB-eDHFR) can be sensitively detected (signal-to-background ratio (S/B)>100) and accurately quantified within an impure cell lysate matrix using a luminescence resonance energy transfer (LRET) assay. Ascomycin-mediated inhibition of GFP-FKBP-rapamycin-FRB-eDHFR complex formation was also detected at high S/B ratio (>80) and Z'-factor (0.89). The method leverages the selective, stable binding of trimethoprim (TMP)-terbium complex conjugates to eDHFR, and time-resolved, background-free detection of the long-lifetime (～ms) terbium-to-GFP LRET signal that indicates target binding. TMP-eDHFR labeling can be adapted to develop high-throughput screening assays and complementary, quantitative counter-screens for a wide variety of PPI targets with a broad range of affinities that may not be amenable to purification.     

Topographic and biomechanical evaluation of cornea in patients with ichthyosis vulgaris

PurposeTo compare the topographic and biomechanical properties of corneas in eyes of patients with ichthyosis vulgaris (IV) and eyes of healthy individuals.MethodsThirty healthy individuals (control group) and 30 patients with IV (study group) were enrolled in this prospective study. Topographic measurements, including keratometry values, irregularity, and surface asymmetry index in the right eye of each participant were obtained using Scheimpflug camera with a Placido disc topographer (Sirius). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldman-related intraocular pressure (IOPg) were measured using the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was also measured with ultrasonic pachymetry and the Sirius corneal topography system.ResultsTopographic parameters were not significantly different between both groups (p > 0.05). Although mean CH was not significantly different between the groups, the CRF was significantly lower in patients with IV (p = 0.249 and p = 0.005, respectively). The CCT was significantly lower in patients with IV compared to healthy controls (p < 0.001). The IOPg and IOPcc were significantly lower in the patients with ichthyosis than in healthy controls (p = 0.001 and p = 0.004, respectively).ConclusionsThe study demonstrated that while the eyes of patients with IV had corneal topographic findings and corneal hysteresis similar to those of healthy controls, some of corneal biomechanical properties such CRF and CCT and IOP values such as IOPg and IOPcc were significantly lower in patients with IV. These results should be taken into account when planning a corneal refractive surgery and glaucoma screening for patients with IV.     

Transient protein-protein interactions

Transient complexes are crucial for diverse biological processes such as biochemical pathways and signaling cascades in the cell. Here, we give an overview of the transient interactions; the importance of transient interactions as drug targets; and the structural characterization of transient protein-protein complexes based on the geometrical and physicochemical features of the transient complexes' interfaces. To better understand and eventually design transient protein-protein interactions (TPPIs), a molecular perspective of the protein-protein interfaces is necessary. Obtaining high-quality structures of protein-protein interactions could be one way of achieving this goal. After introducing the association kinetics of TPPIs, we elaborate on the experimental techniques detecting TPPIs in combination with the computational methods which classify transient and/or non-obligate complexes. In this review, currently available databases and servers that can be used to identify and predict TPPIs are also compiled.