Effect of low B addition on Al-Zn alloy's hydrogen production performance

Aluminium hydrolysis is a promising method for hydrogen generation due to its instant hydrogen production, simplicity, controllability, and safety properties. Moreover, Al is very common, recyclable, lightweight material and it has no degradation problem to supply hydrogen in energy conversion devices. Hydrogen produced by Al can be easily adapted to fuel cells to convert energy into higher efficiency. In this study, the effect of low B additions (0.1, 0.3, and 0.5 wt.%) to the Al-2wt.%Zn alloy's hydrogen generation performance is investigated. Different temperatures (25, 50, and 80 °C) and different concentrations of NaOH (1, 3, and 5 M) are studied to observe their effects on the hydrogen production and corrosion rate. At 80 °C and 5 M NaOH concentration, in Al-2wt.%Zn-0.5wt.%B alloy, around 83% higher hydrogen generation performance is obtained than Al-2wt.% Zn alloy. The hydrolysis reaction kinetics are investigated with the Arrhenius equation and by low B addition, activation energy of the Al-2wt.%Zn and Al-2wt.%Zn-0.5 wt.%B alloys are decreased from 26.717 kJ mol^?1 to 23.526 kJ mol^?1.     

Liquid diffusion model for drying a stack of rough rice

Drying of a stack of rough rice was experimentally and theoretically investigated. Stacks of rough rice having different heights were dried with forced convection of warm air. A theoretical model was developed for predicting the bulk drying kinetics of a stack of rough rice using the analytical solution of liquid diffusion equation based on Fick's law. Effective diffusion coefficients were obtained minimizing the sum of squared differences between the theoretical results and experimental data obtained for various drying conditions. Drying air temperature is the most effective factor on the total rate of moisture removal from the stack. The bulk drying rate of a stack of rough rice was considerably reduced as compared to that of a single layer as the height of the stack increased. Agreement between the theoretical and experimental result is very good. Copyright © 2003 John Wiley & Sons, Ltd.     

Visible absorption spectra of some novel heteroarylazo disperse dyes derived from 2-hydroxy-1,4-naphthoquinone

Synthesis of eight novel heteroarylazonaphthoquinone dyes has been carried out by diazotisation of a range of heterocyclic amines in nitrosyl sulphuric acid and coupling these on to 2-hydroxy-1,4-naphthoquinone. The dyes have been characterised by elemental analysis and spectroscopic methods. The effect on the visible absorption spectrum of the substituents present, and external influences such as solvents, pH and temperature, has been investigated in detail.     

Flexible Etherified and Esterified Triphenylethylene Derivatives and Their Evaluation on ER-positive and Triple-Negative Breast Cancer Cell Lines

Tamoxifen (TAM) is a selective estrogen receptor modulator (SERM) with potential clinical benefits for all stages of breast cancer. TAM is primarily metabolized to more potent metabolites via polymorphic CYP2D6. This affects the clinical outcome of TAM treatment. Herein we report novel TAM analogues that can avoid metabolism via CYP2D6. The novel analogues bear a flexible skeleton. Compounds have either an ester group on ring C or homodiaminoalkoxy groups on rings B and C . Compound 6 (E/Z-4-[1-[4-(2-diethylaminoethoxy)phenyl]-3-(4-methoxyphenyl)-2-methyl[propenyl]phenol) was found to be ten-fold more potent than TAM on MCF-7 cells (GI₅₀=0.15 μM). It showed fivefold greater inhibitory activity on MDA-MB-231 cells than TAM (GI₅₀=1.71 μM). Compound 13 (4-{3,3-bis-[4-(3-dimethylaminopropoxy)phenyl]-2-methylallyl}methoxybenzene) was the most potent among the homodiaminoalkoxy derivatives (GI₅₀=0.44) on both MCF-7 and MDA-MB-231 cell lines, respectively. Furthermore, the COMPARE algorithm suggested that it has different molecular targets from those of some other reported anticancer drugs.     

Rapid pH‐dependent phase transition and elasticity of stimuli‐responsive cationic poly(N,N‐dimethylaminoethyl methacrylate) hydrogels prepared with a dimethacrylate crosslinker

Stimuli‐responsive hydrogels prepared from poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) and its copolymers have attracted much interest to serve in biomedical and pharmaceutical applications. To investigate pH‐dependent swelling and elasticity, a series of cationic hydrogels based on N,N‐dimethylaminoethyl methacrylate were prepared by free radical crosslinking copolymerization at 60 °C in the presence of tetraethylene glycol dimethacrylate as the crosslinker. The equilibrium swelling and the mechanical properties of the PDMAEMA hydrogels were investigated as a function of the gel preparation concentration. To explain the effect of pH on the equilibrium swelling of the hydrogels, pH‐dependent swelling studies were carried out in solutions of pH ranging from 2.1 to 10.7. It was found that the PDMAEMA hydrogels exhibit a rapid pH‐dependent phase transition in aqueous solutions; that is, the gels first remain in the swollen state at acidic pH then collapse in a very narrow range of pH. The results showed that the volume of PDMAEMA hydrogels in acidic conditions is about 10‐ to 40‐fold larger than that in the basic pH region. By using the Flory–Rehner theory, the characteristic network parameters of the PDMAEMA hydrogels were calculated and good agreement obtained between the swelling equilibria of hydrogels and their mechanical properties over the whole range of gel preparation concentration. © 2012 Society of Chemical Industry     

Investigation of mechanical and thermodynamic properties of pH‐sensitive poly(N,N‐dimethylaminoethyl methacrylate) hydrogels prepared with different crosslinking agents

pH‐sensitive poly(N,N‐dimethylaminoethyl methacrylate) hydrogels were synthesized by free‐radical crosslinking polymerization using two different crosslinking agents; tetraethylene glycol dimethacrylate (TEGMA) and N,N′‐methylenebis(acrylamide) (BAAm). The influence of the polymerization factors such as the type of the crosslinking agent and the gel preparation concentration on the swelling behavior, the gel strength, the effective crosslinking density and the average chain length between the crosslink points for the resulting hydrogels was investigated. The results of the equilibrium swelling measurements in water showed that the linear swelling ratio of the resulting hydrogels increases with increasing gel preparation concentration. The swelling ratio of PDMAEMA hydrogels crosslinked with BAAm is larger than those for hydrogels crosslinked with TEGMA over the entire range of the polymer network concentration. The hydrogels exhibit very sharp pH‐sensitive phase transition in a very narrow range of pH between 7.7 and 8.0. From the mechanical measurements, it was also found that the linear swelling ratio of resulting hydrogels depends on the crosslinking density and also the type of the crosslinker used in the preparation. The resulting hydrogels are thought to be good candidates for pH‐sensitive drug delivery systems. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers     

Photochemically initiated free radical promoted living cationic polymerization of isobutyl vinyl ether

A new photoinitiating system for living cationic polymerization of vinyl ethers such as isobutyl vinyl ether (IBVE) has been reported. The photoinitiating system comprises free radical photoinitiators such as 2,2-dimethoxy-2-phenyl acetophenone (DMPA), benzophenone or thioxanthone, together with an onium salt, such as diphenyliodonium chloride and zinc bromide. In the first step, photochemically generated free radicals are oxidized to the corresponding carbocations which subsequently react with vinyl ether monomer to yield an adduct. In the presence of zinc salt, this adduct initiates living cationic polymerization of IBVE.     

Elasticity of poly(acrylamide) gel beads

Summary The elastic behavior of swollen ionic poly(acrylamide) (PAAm) gel beads was investigated as a function of the bead diameter. For this purpose, an experimental setup was designed to measure the modulus of hydrogel beads. An inverse suspension polymerization technique was used to obtain spherical beads of sizes 3 to 11 mm. It was observed that the effective crosslink density of PAAm gel beads produced in the same synthesis batch increases with increasing bead diameter, which was attributed to the inverse suspension polymerization condition. Received: 6 November 2002/Revised version: 4 April 2003/ Accepted: 4 April 2003 Correspondence to Oguz Okay