Performance Evaluation of Sleep Mode on Power Saving in WiMAX IEEE 802.16m and LTE DRX

Power saving represents a vital role in mobile communications networks such as IEEE 802.16m and LTE. Modern user equipment (UE_s) require high data rates and low power consumption. It is found that arranging sleep mode mechanisms ensures UE battery longer lifetime. In this paper, different sleep mode mechanisms are investigated for both IEEE 802.16m and LTE networks. The analyses are based on Markov and Semi-Markov chains. It is focused on the determination of UE transition state. Web traffic model parameters were considered in MATLAB simulation and a comparison assessment was conducted between WiMAX IEEE 802.16m and LTE DRX. It was found that LTE DRX sleep mode provides more power saving than WiMAX IEEE 802.16m sleep mode. The study is now implemented for 5G networks with encouraging results.     

Engineering protein and peptide building blocks for nanotechnology

The tremendous diversity in the structure and function of proteins has stimulated intense interest in using them for nanotechnology applications. In this review, we discuss recent developments in the engineering of proteins and peptides for the design and construction of functional and structural elements of nanodevices. We begin with a short discussion highlighting the differences between chemical and biological synthesis of proteins and peptides. Subsequently, we review recent applications of proteins and peptides as molecular motors, transducers, biosensors, and structural elements of nanodevices. We supplement this review with highlights of our own work in the areas of peptide-based transducers for stand-alone and intra-molecular applications. This is followed by a short discussion of nanotechnology safety issues, and how proteins and peptides may enable the development of biocompatible nanomaterials. The future outlook for protein and peptide-based nanomaterials is then discussed, with an eye toward the significant impact of improved computational techniques on the field.     

Production of porous silica by the combustion of rice husk ash for tundish lining

In order to study the production of porous silica compacts by the combustion of rice husk ash （RHA） for tundish lining, the experimental design technique was used to evaluate the effect of firing temperature, soaking time and compaction pressure on controlling both the porosity degree and compressive strength of rice husk ash compacts. The results revealed that while the porosity degree of the compacts decreased with the increase in the entire studied parameters, the compressive strength exhibited another trend especially at a lower soaking time. At a lower soaking time, the increase in firing temperature led to a slight decrease in compressive strength and then increasing thereafter. The porous silica compacts having 30% porosity and 〉 2.5 MPa compressive strength suitable for tundish lining could be obtained from the combustion of rice husk ash compacts.     

Modelling and simulation of Proton Exchange Membrane fuel cell with serpentine bipolar plate using MATLAB

This report presents experimental results derived from a Proton Exchange Membrane fuel cell with a serpentine flow plate design. The investigation seeks to explore the effects of some parameters like cell operational temperature, humidification and atmospheric pressure on the general performance and efficiency of PEM fuel cell using MATLAB. A number of codes were written to generate the polarization curve for a single stack and five (5) cell stack fuel cell at various operating conditions. Detailed information of hydrogen and oxygen consumption and the effect they have on the fuel cell performance were critically analysed. The investigation concluded that the open circuit voltage generated was less than the theoretical voltage predicted in the literature. It was also noticed that an increase in current or current density reduced the voltage derived from the fuel cell stack. The experiment also clearly confirmed that when more current is being drawn from the fuel cell, more water will also be generated at the cathode section of the cell hence the need for an effective water management to improve the performance of the fuel cell. Other parameters like the stack efficiency and power density were also analysed using the experimental results obtained.     

Recovery of high surface area alumina from aluminium dross tailings

Aluminium dross tailings (ADT), a chemical waste from a factory producing aluminium in Egypt, was used for the recovery of the aluminium content in the form of alumina (Al₂O₃). Extraction of the aluminium was carried out via atmospheric‐ and high‐pressure leaching with caustic soda. Then, it was separated from the sodium aluminate solutions thus obtained, using six different precipitation methods. The precipitates were filtered, washed, dried and calcined at 600 °C to produce the test aluminas. The precipitates and the calcination products were analysed for their chemical and crystalline phase compositions. The calcination products (aluminas) were subjected to sorpometry for surface area determination, and to particle sizing. The results indicated that highly pure (SiO₂ < 0.53% and Na₂O < 0.14%), well‐defined crystalline γ‐aluminas of high surface areas (>200 m² g⁻¹) and uniform small crystallite sizes (60–70 Å) could be efficiently recovered from ADT. Optimal recovery conditions were examined and determined. © 2000 Society of Chemical Industry     

Effect of Some Additives on Mass Transfer Coefficient at a Vibrating Horizontal Screen

The object of the present work is to study the effect of drag-reducing additives like Polyox WSR 301 and sodium lauryl sulfate (anionic surfactant) on the rate of mass transfer at a vibrating horizontal screen, an electrochemical technique which involved measuring the limiting current of the cathodic reduction of potassium ferricyanide. Variables studied were the concentration of polymer and surfactant, frequency of vibration and amplitude of vibration. It was found that a decrease in the mass transfer coefficient occurs in the presence of surfactant which ranged from 3 to 61.8% depending on the concentration of the surfactant. The addition of a Polyox leads to a decrease in the mass transfer coefficient which ranged from 20 to 74.4% depending on the concentration of the polymer.     

Effect of an electric field on the transport of Th(IV) in the presence of Eu(III) and U(VI) through supported liquid membrane containing di‐2‐ethylhexylphosphoric acid

This paper investigates the transport of Th(IV) ions in nitric acid media through a supported liquid membrane (SLM) impregnated with di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene using an electric field. The transport was carried out in a three compartment cell fitted with microporous cellulose nitrate (SLM) and cation exchange membrane (Nafion). The effect of different parameters including nitric acid concentration in the feed solution, HDEHP concentration in the membrane, and HCl concentration were studied. The optimal conditions for Th(IV) transport were 0.1 mol dm^?3 HDEHP, 10^?3 mol dm^?3 HNO₃ in the feed solution, 1 mol dm^?3 HCl in compartment 2 and 1 mol dm^?3 HCl in compartment 3 at 25 °C. Under the optimal conditions of Th(IV) transport the recovery factor after 90 min was 0.25 without applying an electrostatic field, compared with 0.9 when the electric field was applied. The effect of electric current on the flux of Th(IV) through the membrane was also studied. The flux increased as the current density increased from 10 to 30 mA cm^?2 to reach a maximum value at 30 mA cm^?2 (8 × 10^?9 g eq cm^?2 s^?1). The transport percentages of 0.3 g dm^?3 Th(IV) in the presence of 0.1 g dm^?3 Eu(III) and 1 g dm^?3 U(VI) were 66, 84 and 15%, respectively. The determined selectivities of U(VI)–Th(IV) and Th(IV)–Eu(III) were 0.12 and 0.3, respectively, after 90 min. Therefore, the order of selectivity of this system is Eu(III) > Th(IV) > U(VI). © 2001 Society of Chemical Industry     

A review of CO2 sorbents for promoting hydrogen production in the sorption-enhanced steam reforming process

Sorption-enhanced-steam-reforming (SESR) is a thermochemical conversion technology that produces a high-purity hydrogen stream by utilizing in-situ removal of CO₂ with a sorbent. In this paper, the advantages and disadvantages of CaO based sorbents, alkali-metal based sorbents (Na₂ZrO₃, Li₂ZrO₃ and Li₄SiO₄), hydrotalcite based sorbents, bifunctional materials and sorbents prepared from wastes are briefly discussed, and the techniques to improve the sorption properties of these CO₂ sorbents are summarized. In the process of hydrogen production by sorption-enhanced-steam-reforming, the selection of suitable high-temperature CO₂ sorbent is the key to produce high purity hydrogen. Furthermore, the hydrogen-production performance of the above-mentioned sorbents in the SESR process is investigated and summarized. Finally, a future perspective and some suggestions regarding these five types of sorbents are put forward.     

Site-directed mutagenesis of the hinge peptide from the hemagglutinin protein: enhancement of the pH-responsive conformational change

Environmentally responsive proteins and peptides are increasingly finding utility in various engineered systems due to their ability to respond to the presentation of external stimuli. A classic example of this behavior is the influenza hemagglutinin (HA) fusion protein. At neutral pH, HA exists in a non-fusogenic state, but upon exposure to low pH, the conformation of the structure changes to expose a fusogenic peptide. During this structural change, massive rearrangements occur in a subunit of HA (HA2). Crystallography data has shown that a loop of 28 amino acids (residues 54-81) undergoes a dramatic transition from a random coil to an alpha-helix. This segment connects to two flanking helical regions (short and long) to form a long, continuous helix. Here, we report the results of site-directed mutagenesis study on LOOP-36 to further understand the mechanism of this important stimulus-responsive peptide. The conformational transition of a bacterially expressed LOOP-36 was found to be less dramatic than has been previously reported. The systematic mutation of glutamate and histidine residues in the peptide to glutamines (glutamine scanning) did not impact the conformational behavior of the peptide, but the substitution of the glycine residue at position 22 with alanine resulted in significant pH-responsive behavior. Therefore this mutant stimulus-responsive peptide may be more valuable for future protein engineering and bionanotechnology efforts.