Nonlinear behaviour of epoxy and epoxy-based nanocomposites: an integrated experimental and computational analysis

The focus of this study is on the nonlinear mechanical properties of epoxy and epoxy-based nanocomposites, exploring frequency and strain amplitude dependency. Nanocomposite samples of epoxy are reinforced with fumed silica (FS), halloysite nanotubes (HNT) and Albipox 1000 rubber (Evonik) nanoparticles. Considering these particles have different geometries and stiffnesses, they are expected to have significantly different influences on the mechanics of the resulting composite. To enhance the reliability of the results and to reveal the impact of nanofillers on the mechanics of the material more distinctly, the manufacturing process is designed to be the same for all the specimens within the same material groups to eliminate the effects of the manufacturing process. The comprehensive characterization process consists of Fourier-Transform InfraRed Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Dynamic Mechanical Analysis (DMA). The DMA tests are designed so that the material properties are measured depending on the vibration frequency and strain amplitude. Finally, the characterized nonlinear dynamic properties of these nanocomposites are used as the input material properties into a numerical model. In this simulation, a cantilever beam with representative nonlinear material properties, for these nanocomposites, is created, as example and its forced response is plotted under the same levels of excitation in the frequency domain. Key effects of the different nanofillers are identified using the resonance behavior, primarily focusing on the stiffness and damping of the epoxy-based nanocomposites. These experimental and numerical procedures followed show the significant impact of the nanoparticle reinforcements on the nonlinear nature of these epoxy-based composites

Spectral correlations in a random distributed feedback fibre laser

Random distributed feedback fibre lasers belong to the class of random lasers, where the feedback is provided by amplified Rayleigh scattering on sub-micron refractive index inhomogenities randomly distributed over the fibre length. Despite the elastic nature of Rayleigh scattering, the feedback mechanism has been insofar deemed incoherent, which corresponds to the commonly observed smooth generation spectra. Here, using a real-time spectral measurement technique based on a scanning Fabry-Pérot interferometer, we observe long-living narrowband components in the random fibre laser's spectrum. Statistical analysis of the ∼104 single-scan spectra reveals a preferential interspacing for the components and their anticorrelation in intensities. Furthermore, using mutual information analysis, we confirm the existence of nonlinear correlations between different parts of the random fibre laser spectra. The existence of such narrowband spectral components, together with their observed correlations, establishes a long-missing parallel between the fields of random fibre lasers and conventional random lasers

Toward community standards and software for whole-cell modeling

Whole-cell (WC) modeling is a promising tool for biological research, bioengineering, and medicine. However, substantial work remains to create accurate, comprehensive models of complex cells. Methods: We organized the 2015 Whole-Cell Modeling Summer School to teach WC modeling and evaluate the need for new WC modeling standards and software by recoding a recently published WC model in SBML. Results: Our analysis revealed several challenges to representing WC models using the current standards. Conclusion: We, therefore, propose several new WC modeling standards, software, and databases. Significance:We anticipate that these new standards and software will enable more comprehensive models

A general analysis of the animals brought to he Clinics of Obstetrics and Gynecology of Faculty of Vetrinary, University of Ankara Between years 1987-2001

Ankara Üniversitesi Veteriner Fakültesi Doğum ve Jinekoloji Kliniğine 1987-2001 yılları arasında 12782 hayvan getirilmiştir. Bu hayvanların %28.64'ünü sığır (%26.74 inek, %1.90 düve), %32.46'sını köpek, %33.54'ünü kedi, %2.48'ini koyun, %1.34'ünü keçi, %1.04'ünü kanatlı, %0.20'sini manda, %0.17'sini tavşan ve %0.14'ünü kısrak oluşturmuştur. Ocak, Mart ve Nisan aylarında daha fazla hastanın geldiği belirlenmiştir. En fazla hasta 1994 yılında (%8.62), en az hasta ise 2000 yılında (% 4.93) getirilmiştir.Totally 12782 animals were brought to the Clinics of Obstetrics and Gynecology of Faculty of Veterinary, University of Ankara between years 1987-2001. 26.74% of this animals were cows, 1.90% were heifers, 32.46% were dogs, 33.54% were cats, 2.48% were sheep, 1.34% were goats, 1.04% were poultry, 0.20% were water buffalo, 0.17% were rabbits and 0.14% were mares. It was detected that more animals were brought to the clinics in January, March and April. The maximum number of cases was seen in 1994 (8.62%), the minimum was in 2000 (4.93 %)

NLO and NBO Analysis of Sarcosine-Maleic Acid by Using HF and B3LYP Calculations

We report a theoretical study on molecular structure, vibrational spectra, nonlinear optical (NLO), and natural bond orbital (NBO) analysis of sarcosine-maleic acid (C7H11NO6) in the ground state calculated by using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6–31++G(d,p) basis set. We repeat NBO calculations with 6–31G(d,p) basis set so as to see the diffuse function impact on NBO analysis. Stability of the molecule arising from hyper conjugative interactions and charge delocalization has been analyzed using NBO analysis. NBO analysis shows that there is a O–H⋯O and N–H⋯O hydrogen bond in the title compound, which is consistent with the conclusion obtained by the analysis of molecular structure. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Also, these results are supported by the NLO parameters. Finally, the calculated results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with experimental ones

Comparison of Logistic Regression and Discriminate Analysis in Recognition of the Factors Affecting on the Distribution of Quercus Libanii of Armardeh Forests at Baneh, Kurdistan Province

The study site, Armardeh forest, is located in Baneh, Kurdistan Province. The study area covers approximately 17000 ha. In this study, logistic regression and discriminant analysis methods were used and their performances were compared. Two random sampling grids were overlaid on the presence and absence area of Quercus libani type as dependent variables. Physiographic factors including slope, aspect, elevation and distance from drains were extracted for each sampling site and considered as independent variables. The results showed that the area under the ROC curve (0.746) for logistic regression method is higher than the discriminant analysis with 0.502. Furthermore, the overall accuracy of the classification of the logistic regression was higher than discriminate analysis. The results of this study can be used in management and restoration of these forests

Congenital chondrodysplasic dwarfism in lambs: A diferent consideration of dystocia

In this study, we report three chondrodysplasic anomalous lambs obtained from 2 Akkaraman sheep with dystocia. According to the flock history, the incidence of congenital skeletal anomalies among lambs was 14.28 % and 11.66 % in 2005 and 2006, respectively. The same two rams had been used to obtain natural mating and no new animals had been bought into the flock over the last 5 years. Affected lambs showed typical macroscopic features of a compressed and flattened face, domed head, narrow thorax, swollen abdomen and extremely short paddle like extremities. Radiological examination of extremities of the long bones revealed that diaphyses were extremely shortened and distance between diaphysis and epiphysis was increased. Long bones such as antebrachium, humerus, tibia and femur were short and thick. Histopathologically, immature chondrocytes were present at the articular surface and defective epiphyseal plates were detected in the extremities of the bones and sternum. Persistent cartilage showed irregular strands containing groups of two or four chondrocytes localized in the basophilic matrix. In conclusion, chondrodysplasia of lambs should be added to the list of differential diagnoses of dystocia especially in inbreed sheep

Density functional theory calculations on conformational, spectroscopic and electrical properties of 3-(2,3-dimethoxyphenyl)-1-(pyridin-2-yl)prop-2-en-1-one: a potential nonlinear optical material

Quantum chemical calculations of the ground state energy, the highest and lowest energy conformers and vibrational wavenumbers of 3-(2,3-dimethoxyphenyl)-1-(pyridin-2-yl)prop-2-en-1-one have been performed by using Gaussian 09 program. B3LYP and HSEH1PBE levels of density functional theory with the 6-311++G(d,p) basis set have been used to perform above-mentioned calculations. The vibrational wavenumbers have been assigned on the basis of potential energy distribution analysis. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. The frontier molecular orbitals have been simulated, and obtained small energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital energies has confirmed that charge transfer occurs within title compound. Nonlinear optical behavior of the title compound has been investigated by determining electric dipole moment, polarizability and hyperpolarizability. Finally, the molecular electrostatic potential surface and density of state have been simulated to find more reactive sites for electrophilic and nucleophilic attack