Female Germ Cell Development,Functioning and Associated Adversities under Unfavorable Circumstances

In the present era, infertility is one of the major issues which restricts many couples to have their own children. Infertility is the inability to achieve a clinical pregnancy after regular unprotected sexual intercourse for the period of one year or more. Various factors including defective male or female germ cell development, unhealthy and improper lifestyles, diseases like cancer and associated chemo-or-radiation therapies, congenital disorders, etc., may be responsible for infertility. Therefore, it is highly important to understand the basic concepts of germ cell development including primordial germ cell (PGC) formation, specification, migration, entry to genital ridges and their molecular mechanisms, activated pathways, paracrine and autocrine signaling, along with possible alteration which can hamper germ cell development and can cause adversities like cancer progression and infertility. Knowing all these aspects in a proper way can be very much helpful in improving our understanding about gametogenesis and finding possible ways to cure related disorders. Here in this review, various aspects of gametogenesis especially female gametes and relevant factors causing functional impairment have been thoroughly discussed.     

Oxidative Inorganic Multilayers for Polypyrrole Film Generation

A controlled nanoscale fabrication of conducting polymer films sets severe requirements for the preparation method and substrate. A new and versatile approach for producing thin polypyrrole films on a variety of surfaces is presented. Purely inorganic thin films are first prepared from poly(metaphosphate) and tetravalent metal ions using a sequential layer‐by‐layer technique. Redox‐active cerium(IV) polyphosphate multilayer and redox‐inactive zirconium(IV) and hafnium(IV) polyphosphate multilayers are prepared. Cerium‐based polyphosphate films grow exponentially with the number of layers but multilayers containing zirconium or hafnium exhibit a linear buildup process. All the studied systems produce relatively smooth films with initial bilayer thickness less than 2 nm. The cerium(IV) containing film is redox‐active, which is shown by its capability to form a polypyrrole layer on its surface by oxidation of pyrrole monomers in the adjacent aqueous solution. This is a general method to produce thin oxidative films of arbitrary size and form on a wide variety of surfaces.     

An automated methodology to select functional co-simulation configurations

Multibody System Dynamics - The development of machinery often requires system-level analysis, in which non-mechanical subsystems, such as hydraulics, need to be considered. Co-simulation allows...     

Compressibility of porous TiO2 nanoparticle coating on paperboard

Compressibility of liquid flame spray-deposited porous TiO₂ nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO₂ nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure.

PACS

61.46.-w; 68.08.Bc; 81.07.-b     

Zero-Forcing Spatial Interweave with Greedy Scheduling

In this work, the effect of the multipath on the capacity and the interference statistics of the sectors of the highways cigar-shaped W-CDMA microcells is studied. A model of five microcells is used to analyze the uplink. The capacity and the interference statistics of the microcell are studied for different antenna sidelobe levels and different sector ranges. In the study, imperfect power control and limited transmitted power are assumed. Users are assumed to be within equally spaced buses and cars. The uplink capacity of the sector is studied assuming three types of services, namely, voice, 3G data and 3.75G data (representing the High Speed Uplink Packet Access). It is shown that, the sector uplink capacity depends on the buses and cars density within the sector. The capacity is also given as a function of the number of buses and cars within the sector.     

Block and Graft Copolymers of Poly(ethylene glycol) and Poly(dimethylsiloxane) for Blood Contacting Biomedical Materials Applications

The incorporation of both hydrophobic and hydrophilic groups into a synthetic polymer is a potent way of controlling its surface and interfacial properties. With this end result in mind, we describe herein the synthesis and characterization of poly(dimethylsiloxane-b-ethyleneoxide) block copolymers (PDMS-b-PEO) and poly(dimethylsiloxane-g-ethyleneoxide) grafted copolymers (PDMS-g-PEO). These amphiphillic copolymers were also investigated as surface modifying agents for passifying hydrophobic polymer surfaces in blood contacting applications. Specifically, the various (PDMS-b-PEO) and (PDMS-g-PEO) copolymers were coated onto poly(styrene-divinylbenzene) microspheres by their physical adsorption from solution. These surfaces were then evaluated for blood contacting applications utilizing a fibrinogen and thrombin protocol. In particular, the binding of fibrinogen and the functionality of the surface bound fibrinogen on an otherwise hydrophobic surface (polystyrene) was investigated. As the conversion of fibrinogen to fibrin is facilitated by thrombin, the aggregation of the copolymer-coated hydrophobic microspheres was followed using an optical method after the sequential exposure of the microspheres to fibrinogen and then to thrombin. We were able to determine how the adsorbed copolymers affected the functionality of the bound fibrinogen at an interface. Our hypothesis is that the hydrophobic siloxane units of the copolymers will be in close proximity to the polystyrene surface and that the PEO will extend out from the surface and therefore render the synthetic polymer system hemocompatible. Following the fibrinogen and thrombin protocol and determining the fibrinogen-dependent aggregation, the results show that the PDMS-b-PEO copolymers (having a PEO content from 4.6 to 11.5 weight %) were similar in terms of particle aggregation when compared to the pure polystyrene microspheres (blank) or to the microspheres that were coated with a linear PDMS homopolymer. By comparison, the PDMS-g-PEO copolymers (having a PEO content from 58 to 80 weight %) were seen to reduce the fibrinogen functionality on the microsphere system surface. Thus the data indicate that the PDMS-g-PEO copolymers can behave like molecular brushes that are able to pacify the surface of the hydrophobic polystyrene microspheres. A somewhat unexpected observation was that for the copolymer system having a low PEO content the fibrinogen-dependent aggregation of the otherwise hydrophobic microspheres was observed to increase relative to the pure microspheres (blank). It is clear from the findings of this investigation that the surface packing and molecular orientation of both the adsorbed copolymer and also of the fibrinogen are important factors that govern the properties and applications of blood contacting biomaterials.     

Computational fractal geometry with WFA

We define two measures of “fractalness” of gray-tone images: the degree of self-similarity and the gray-tone fractal dimension as a generalization of Minkovski dimension of compact sets. We show how to compute both these measures from the WFA-representation of a gray-tone image. Since we have developed a WFA-inference algorithm which computes a good approximation of any gray-tone image we can compute a close approximation of both our measures of fractalness for any gray-tone image. Received: 15 November 1994 / 6 October 1995     

Novel luminescent samarium(III) chelates

A series of new stable, luminescent samarium(III) chelates were synthesized and their photophysical properties were measured. The iodoacetamido activated chelate coupled to a peptide was used in a caspase-3 assay.