Superabsorbent

Superabsorbent hydrogel (SAH) is a cross-linked polyelectrolyte polymer that has the capability to absorb a lot of water by keeping it in a three-dimensional (3D) structure. The network’s structure of SAH has the high elasticity that gives the ability of pores to expand in an aqueous media into up to 150–1500 times their own size in a dry state. The size of pores is the major factor that controls the swelling degree of the hydrogel. In contrast, the swelling degree is related to cross-linked density and the number of polarizable functional groups that immobilize on the polymer backbone. The hydrogels could be made by radical-initiated polymerization of hydrophilic monomers, and/or linear polymers dissolve in an aqueous solution. Free radical polymerization of the hydrogel can be done physically or chemically. Advantages and disadvantages of each method will be elaborated in this chapter. The advances in radiation cross-linking methods for the hydrogel preparation are particularly addressed besides other different techniques, e.g., (freezing/thawing and chemical initiation). This chapter will review the preparation methods of superabsorbent hydrogels from synthetic and natural hydrophilic polymers with other new phases such as wax, gum, and rubber. Methods to characterize these hydrogels and their proposed applications (internal curing agent for cement, agricultural proposal, biomedical proposal, and environmental proposal) are also reviewed

Ionizing Radiation-Induced Polymerization

Ionizing radiation can induce some kinds of reactions, other than polymerization, such as dimerization, oligomerization, curing, and grafting. These reactions occur through a regular radical chain causing growth of polymer by three steps, namely, initiation, propagation, and termination. To understand ionizing radiation-induced polymerization, the water radiolysis must be taken into consideration. This chapter explores the mechanism of water molecules radiolysis paying especial attention to the basic regularities of solvent radicals’ interaction with the polymer molecules for forming the crosslinked polymer. Water radiolysis is the main engine of the polymerization processes, especially the “free-radical polymerization.” The mechanisms of the free-radical polymerization and crosslinking will be discussed in detail later. Since different polymers respond differently to radiation, it is useful to quantify the response, namely in terms of crosslinking and chain scission. A parameter called the G-value is frequently used for this purpose. It represents the chemical yield of crosslinks, scissions and double bonds, etc. For the crosslinked polymer, the crosslinking density increases with increasing the radiation dose, this is reflected by the swelling degree of the polymer while being immersed in a compatible solvent. If crosslinking predominates, the crosslinking density increases and the extent of swelling decreases. If chain scission predominates, the opposite occurs. A further detailed discussion of these aspects is presented throughout this chapter

Synthesis of Nucleoside Polyphosphates and their Conjugates

Nucleoside polyphosphates and their conjugates, such as nucleoside triphosphates, nucleoside tetraphosphates, sugar nucleotides, dinucleoside pyro- and higher order polyphosphates, 2’,3’-cyclic nucleoside monophosphates, and 2´-deoxynucleoside-5´-tetraphosphates in which a fluorescent label is attached to the terminal phosphate have many biological roles and have been developed into drugs. However, their synthesis remains a challenge. Several novel and efficient approaches to the synthesis of nucleoside polyphosphates and their conjugates were developed. In the first approach dinucleoside polyphosphates (NpnN’s where n = 2-4) are prepared via in situ trifluoroacetate protection and imidazolium activation of nucleoside 5’-monophosphates. This methodology was also used to prepare a substrate-intermediate analog of the reaction catalyzed by cytidine triphosphate synthase (CTPS) a recognized target for the development of antineoplastic, antiviral and antiprotozoal agents. The second approach uses sulfonylimidazolium salts as key reagents for generating highly reactive nucleotide donors. The procedure is rapid, produces a wide variety of nucleoside polyphosphates and their conjugates in high yield, does not require protection and subsequent deprotection of the nucleotide donors or acceptors and can be used to activate nucleoside mono-, di-, and triphosphates and a wide variety of acceptors. Finally an entirely new approach to the synthesis of nucleoside tetraphosphates (Np4’s), dinucleoside pentaphosphates (Np5N’s) and nucleoside tetraphosphates in which a fluorescent dye is attached to the terminal phosphate is described employing an activated form of cyclic trimetaphosphate as a novel phosphorylating agent. Attempts to prepare nucleoside triphosphates by subjecting unprotected ribonucleosides and 2’-deoxyribonucleosides to activated cyclic trimetaphosphate failed. Instead nucleoside 2’,3’-cyclic phosphates were obtained in good yield with the ribonucleoside substrates. This represents a new and convenient approach to the synthesis of this class of compounds.4 month

POTENTIAL OF STATIC, KINEMATIC, AND RTK IN OPEN SKY USING GPS ONLY AND GPS + GLONASS SIGNALS

ABSTRACT: It is now simple to use Global Navigation Satellite System (GNSS) anyplace due to the rapid developments and variety of GNSS satellite techniques. Several satellite systems, including GPS, GLONASS, BIUDO, and GALILEO, are widely available and used. The Differential Global Navigation Satellite System (DGNSS) is being utilized for many different applications, particularly those involving surveying and mapping. For establishing control points (Cps) in the open sky with moderate accuracy, it may be helpful to compare the usage of post-processing methods including static and kinematic also real-time kinematic (RTK) for position accuracy to differentiate their accuracies. The comparison depends on using the constellation of GPS only and GPS + GLONASS. For this purpose, fieldwork employing the three approaches with the two constellations (GPS and GLONASS) was done on five test points. The selected points were in the open sky, and the raw data was collected on tripods in the three methods. Leica 8.4 Geo Office software was used for the raw data processing after the five Cps were observed using a Leica Viva GS15 dual frequency receiver which supports GPS and GLONASS signals. The 3D position accuracy of the Cps was obtained by the three approaches using signals from GPS + GLONASS and GPS only. The advantages and disadvantages of using each approach were discusse

POTENTIAL OF STATIC, KINEMATIC, AND RTK IN OPEN SKY USING GPS ONLY AND GPS + GLONASS SIGNALS

ABSTRACT: It is now simple to use Global Navigation Satellite System (GNSS) anyplace due to the rapid developments and variety of GNSS satellite techniques. Several satellite systems, including GPS, GLONASS, BIUDO, and GALILEO, are widely available and used. The Differential Global Navigation Satellite System (DGNSS) is being utilized for many different applications, particularly those involving surveying and mapping. For establishing control points (Cps) in the open sky with moderate accuracy, it may be helpful to compare the usage of post-processing methods including static and kinematic also real-time kinematic (RTK) for position accuracy to differentiate their accuracies. The comparison depends on using the constellation of GPS only and GPS + GLONASS. For this purpose, fieldwork employing the three approaches with the two constellations (GPS and GLONASS) was done on five test points. The selected points were in the open sky, and the raw data was collected on tripods in the three methods. Leica 8.4 Geo Office software was used for the raw data processing after the five Cps were observed using a Leica Viva GS15 dual frequency receiver which supports GPS and GLONASS signals. The 3D position accuracy of the Cps was obtained by the three approaches using signals from GPS + GLONASS and GPS only. The advantages and disadvantages of using each approach were discusse

Synaptic Plasticity and Memory: New Insights from Hippocampal Left-Right Asymmetries.

All synapses are not the same. They differ in their morphology, molecular constituents, and malleability. A striking left-right asymmetry in the distribution of different types of synapse was recently uncovered at the CA3-CA1 projection in the mouse hippocampus, whereby afferents from the CA3 in the left hemisphere innervate small, highly plastic synapses on the apical dendrites of CA1 pyramidal neurons, whereas those originating from the right CA3 target larger, more stable synapses. Activity-dependent modification of these synapses is thought to participate in circuit formation and remodeling during development, and further plastic changes may support memory encoding in adulthood. Therefore, exploiting the CA3-CA1 asymmetry provides a promising opportunity to investigate the roles that different types of synapse play in these fundamental properties of the CNS. Here we describe the discovery of these segregated synaptic populations in the mouse hippocampus, and discuss what we have already learnt about synaptic plasticity from this asymmetric arrangement. We then propose models for how the asymmetry could be generated during development, and how the adult hippocampus might use these distinct populations of synapses differentially during learning and memory. Finally, we outline the potential implications of this left-right asymmetry for human hippocampal function, as well as dysfunction in memory disorders such as Alzheimer's disease.The author's research was supported by the Biotechnology and Biological Sciences Research Council (BBSRC), UK. M.E-­G. is supported by a BBSRC Studentship.This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/107385841455065

Integrated approach of the dynamic characteristics optimization for spacecraft’s technical systems on the exploratory tests

Integrated approach is the process connecting various project, theoretical and testing procedures. It is provided by the specific series-parallel combination of the mentioned operations. This paper shows that using results of the previous procedures on the further algorithm stages of exploratory tests and product verification is expedient. At that, the necessary correcting of engineering solutions in corresponding procedures is conducted simultaneously. Then, results of each procedure are used in the fixed sequence. It provides maximum attainable optimality of the designed system

Structural Behavior of Composite Reinforced Ferrocement Plates

The results of an experimental investigation to examine the structural behavior of composite reinforced ferrocement concrete plates are presented in this paper. The precast permanent ferrocement forms are proposed as a viable alternative to the steel panels in some of its uses. The experimental program comprised casting and testing of eighteen reinforced ferrocement plates having the dimensions of 550mm width, 1100mm length and different thicknesses (60, 80,100) mm. Each control plate was reinforced with four steel bars of 6mm diameter at the bottom of the plate and six steel bars of 6mm diameter at the transverse direction. Two types of steel mesh were used to reinforce the ferrocement plates. These types are: galvanized welded wire mesh of size of opening 12.5x12.5mm, and (33 X 16.5mm) expanded metal wire mesh of diamond size 33x16.5mm. Single layer, double layers and three layers of each type of the steel mesh were employed. All specimens were tested under 3-lines flexural loadings. The flexural performances of the all tested plates in terms of strength, stiffness, cracking behavior, ductility and energy absorption properties were investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and good energy absorption properties could be achieved by using the developed ferrocement plates.

Permanence in a class of delay differential equations with mixed monotonicity

In this paper we consider a class of delay differential equations of the form $\dot{x}(t)=\alpha (t) h(x(t-\tau), x(t-\sigma))-\beta(t)f(x(t))$, where $h$ is a mixed monotone function. Sufficient conditions are presented for the permanence of the positive solutions. Our results give also lower and upper estimates of the limit inferior and the limit superior of the solutions via a special solution of an associated nonlinear system of algebraic equations. The results are generated to a more general class of delay differential equations with mixed monotonicity

Permanence in a class of delay differential equations with mixed monotonicity

In this paper we consider a class of delay differential equations of the form x˙(t) = α(t)h(x(t − τ), x(t − σ)) − β(t)f(x(t)), where h is a mixed monotone function. Sufficient conditions are presented for the permanence of the positive solutions. Our results give also lower and upper estimates of the limit inferior and the limit superior of the solutions via a special solution of an associated nonlinear system of algebraic equations. The results are generated to a more general class of delay differential equations with mixed monotonicity