Quantitative analysis of sperm rheotaxis using a microfluidic device

Quite puzzling issue in biology is how sperm cells are selected naturally where human sperm has to maintain a correct swimming behavior during the various stages of reproduction process. In nature, sperm has to compete a long journey from cervix to oocyte to stand a chance for fertilization. Although various guidance mechanisms such as chemical and thermal gradients are proposed previously, these mechanisms may only be relevant as sperm reaches very close to the oocyte. Rheotaxis, a phenomenon where sperm cells swim against the flow direction, is possibly the long-range sperm guidance mechanism for successful fertilization. A little is known quantitatively about how flow shear effects may help guide human sperm cells over long distances. Here, we have developed microfluidic devices to quantitatively investigate sperm rheotaxis at various physiological flow conditions. We observed that at certain flow rates sperm actively orient and swim against the flow. Sperm that exhibit positive rheotaxis show better motility and velocity than the control (no-flow condition), however, rheotaxis does not select sperm based on hyaluronic acid (HA) binding potential and morphology. Morphology and HA binding potential may not be a significant factor in sperm transport in natural sperm selection.     

Vertex-Edge Degree Based Indices of Honey Comb Derived Network

Chemical graph theory is a branch of mathematics which combines graph theory and chemistry. Chemical reaction network theory is a territory of applied mathematics that endeavors to display the conduct of genuine compound frameworks. It pulled the research community due to its applications in theoretical and organic chemistry since 1960. Additionally, it also increases the interest the mathematicians due to the interesting mathematical structures and problems are involved. The structure of an interconnection network can be represented by a graph. In the network, vertices represent the processor nodes and edges represent the links between the processor nodes. Graph invariants play a vital feature in graph theory and distinguish the structural properties of graphs and networks. In this paper, we determined the newly introduced topological indices namely, first -degree Zagreb index, first -degree Zagreb index, second -degree Zagreb index, -degree Randic index, -degree atom-bond connectivity index, -degree geometric-arithmetic index, -degree harmonic index and -degree sum-connectivity index for honey comb derived network. In the analysis of the quantitative structure property relationships (QSPRs) and the quantitative structureactivity relationships (QSARs), graph invariants are important tools to approximate and predicate the properties of the biological and chemical compounds. Also, we give the numerical and graphical representation of our outcomes.     

Grain boundary embrittlement in Cu-AI-Niβ-phase alloys

The grain boundary embrittlement in Cu-AI-Ni-phase alloys has been investigated. The study included both the bulk alloys and rapidly solidified ribbons. It was observed that the fracture characteristics and the phase transformations in rapidly solidified ribbons were similar to those in the bulk alloys. Various factors responsible for intergranular fracture were considered. It was found that intrinsic or extrinsic precipitates at the grain boundaries are not responsible for the embrittlement. It was further observed that the segregation of impurities does not occur at the grain boundaries and hence is not a factor contributing to the embrittlement. The intrinsic characteristics, however, appear to play an important role. These may include high elastic anisotropy, ordered structure and plastic incompatibility. Severe embrittlement in high-nickel alloys is associated with spinodal decomposition occurring in these alloys. The large grain size exhibited by these alloys is found not to be a significant factor contributing to the embrittlement.     

Coke deposition and run length in industrial naphtha thermal cracking furnaces via a quasi-steady state coupled CFD model

Mathematical modelling of the thickness of the coke layer growing over months in millisecond cracking reactors is a dilemma in computational fluid dynamics (CFD) simulation. To address the time scale issue, a quasi-steady state (QSS) approach was employed through a comprehensive coupled reactor/firebox CFD model in the current study. The model was applied to predict the time-dependent behaviour of coke deposition and to determine the appropriate operating conditions for maximum olefin yields over an industrial furnace run length. A novel algorithm was designed to overcome the complexity of QSS simulation of the CFD model, which is a combination of reactive turbulence flow, combustion, and radiation models. The furnace parameters were studied as a function of two variables: the dilution steam-to-feed ratio and the liberated heat by the burners. The results indicated that the run length can be extended by up to 20% while retaining the main product yields. This study offers practical suggestions to maximize the run length in the operation.     

Using genetic algorithm for the optimization of seismic behavior of steel planar frames with semi-rigid connections

Beam-column connections have a significant role in the results of the analysis and the design of steel frames. In this paper, a genetic algorithm has been used for the non-linear analysis and design of steel frames. For minimizing the weight of frames, while satisfying the applied constraints and restraints such as the limits of normal and combined stresses, criteria such as target displacement(s) and the number and locations of plastic hinges were used. To analyze and design the frame elements, I and box-shaped standard sections were used for beams and columns, respectively. Finally, some clues for finding optimizing semi-rigid connection stiffness values for beam-to-column connections have been obtained. The degrees of these rigidities are obtained by a genetic algorithm during the procedure of optimization in order to reach a frame with the minimum weight. SAP2000 structural analysis program was used to perform modal analysis and linear and non-linear static solutions as well as the design of the elements. A MATLAB program was written for the process of optimization. The procedure of optimization was based on a weight minimization carried out for 9 steel frames. Thus, the optimum connection stiffness could be obtained for minimizing the weight of the structure. The results show that the non-linear analysis gives less weight for short period frames with semi-rigid connections compared to those of linear ones. However, by increasing the periods of frames, much less weights are obtained in the case of non-linear analysis with semi-rigid connections.     

Ricinoleic acid inPhyllanthus niruri seed oil

Seed oil ofPhyllanthus niruri (Euphorbiaceae) contains 1.2% ricinoleic (12-hydroxy-cis-9-octadecenoic) acid, previously unknown in the genusPhyllanthus. Identification is based on thin layer and gas liquid chromatography, infrared, nuclear magnetic resonance, and mass spectrometry analysis as well as chemical methods. Other major components of the oil are linoleic acid (21%) and linolenic acid (51.4%). Presented at the ISF/AOCS World Congress, April 1980, New York City.     

Dual-decay converter for switched reluctance motor drives inlow-voltage applications

A modified converter topology for star-connected switched reluctance motors suitable for low-voltage applications is proposed. A dual-time-constant freewheeling circuit has been designed to improve the drive performance and efficiency over a wide range of speeds. The different modes of operation of the converter are discussed, and a comparison is made with other converter configurations