Novel moisture-cured hyperbranched urethane alkyd resin for coating application

A hyperbranched polyol (HBP) was synthesized using dipentaerythritol as a core material and 2,2-bis(methylol) propionic acid as a chain extender. This was reacted with varying concentrations of soya fatty acid to make hyperbranched alkyd (HBA) resins. The HBA resins containing unreacted hydroxyl groups were reacted with isophorone diisocyanate at NCO/OH ratio of 1.6:1 to make high solid hyperbranched urethane alkyd (HBUA) resins. The excess NCO content in the HBUA resins was used to cure with atmospheric moisture, and thus moisture-cured HBUA coatings were formed. The resins were characterized by FTIR, and ¹³C NMR spectroscopic analysis. A series of such resins were made using different fatty acid/isocyanate ratios with respect to the hydroxyl groups present in the HBP. The effect of compositions on the mechanical and weathering properties of the cured resins was investigated. It was observed that there was an optimum fatty acid–isocyanate ratio in terms of the requirements of solvent, mechanical and weathering properties of the resin. The requirement of solvents for formulating HBUA coatings is much lower compared to linear alkyd-based coatings. The present study reveals that the moisture-cured HBUA resins can be used as a binder material in the field of low-pollution weather-resistance coatings.     

Application of channel flow double electrode to the study on platinum dissolution during potential cycling in sulfuric acid solution

The applicability of a channel flow double electrode (CFDE) as an in situ monitoring method of Pt dissolution during potential cycling in 0.5 M H₂SO₄ solution at 25 °C was investigated. In the CFDE, Pt ions (Ptⁿ⁺) dissolved from a platinum working electrode were detected by reducing them to Pt on a gold collector electrode which was placed at the downstream. The detection of the Pt dissolution by the collector current was confirmed by EPMA analysis of the collector electrode surface. In anodic scan, a rise of the collector current above 1.05 V clearly indicated the platinum dissolution. The collector current showed two different rates of dissolution, i.e. a lower rate from 1.05 to 1.3 V where only one layer of oxide (PtO) is formed and the higher rate from 1.3 to 1.46 V where two layers of oxides (probably PtO/PtO₂) are formed. The collector current, in the cathodic scan, clearly showed two different reduction peaks due to the Pt deposition, which was confirmed by EPMA analysis. On the basis of collector current, the rate and potential range of the Pt dissolution are discussed.     

Shape memory polymer system of semi-interpenetrating network structure composed of crosslinked poly (methyl methacrylate) and poly (ethylene oxide)

Shape memory semi-interpenetrating polymer networks (semi-IPNs) composed of crystalline poly (ethylene oxide) (PEO) and crosslinked poly (methyl methacrylate) (x-PMMA) have been investigated. The selected compositions show shape memory property with a reasonable fast recovery (recovery time ∼1 min) and shape recovery ratio of 99%. Effects of composition (x-PMMA/PEO = 80/20…60/40) and crosslinker (triethyleneglycol dimethacrylate) concentration (up to 6 wt.%) on the creep property were also studied. The recovery time of the semi-IPNs increased and the creep compliance decreased with increasing crosslinker concentration. The network structure containing PEO crystal was characterized by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) indicated that the PEO, present confined in the semi-IPN, melts at a lower temperature compared to the pure PEO. Dynamic mechanical analysis (DMA) showed a decrease in the glass transition (T_g) of the semi-IPN due to the phase mixing of amorphous PEO and PMMA. Both the glassy and rubbery moduli (E_g and E_r, respectively) were lower for the semi-IPNs than for the x-PMMA network. On the other hand, the E_g/E_r ratio was markedly increased for the semi-IPNs supporting an easy shaping along with a good shape fixing.     

The Benefits of Renewables in Turkey

Renewable energy is proving to be commercially viable for a growing list of consumers and uses. Renewable energy technologies provide many benefits that go well beyond energy alone. More and more, renewable energies are contributing to the three pillars of sustainable development not only in IEA countries, but globally. Turkey is an energy-importing country; more than half of the energy requirement has been supplied by imports. Domestic oil and lignite reserves are limited and lignites are characterized by high ash, sulfur, and moisture content. In this regard, renewable energy resources appear to be one of the most efficient and effective solutions for sustainable energy development in Turkey. Turkey's geographical location has several advantages for the extensive use of most of these renewable energy sources. Because of this and the fact that it has limited fossil fuel resources, a gradual shift from fossil fuels to renewables seems to be serious and the sole alternative for Turkey. This article presents the role of the renewables in future directions in IEA countries with Turkey. At present the share of hydropower and biomass is high as 30% in the primary energy production of Turkey. In the case of solar, geothermal, and wind energy, there is an important potential for domestic heating and electricity generation.     

Role of biomineralization on the degradation of fine grained AZ31 magnesium alloy processed by groove pressing

Groove pressing (GP) has been successfully adopted to achieve fine grain size up to 7 μm in AZ31 magnesium alloy with an initial grain size of 55 μm. The effect of microstructural evolution and surface features on wettability, corrosion resistance, bioactivity and cell adhesion were investigated with an emphasis to study the influence of deposited phases when the samples were immersed in simulated body fluid (SBF 5 ×). The role of microstructure was also evaluated without any surface treatments or coatings on the material. GPed samples exhibit improved hydrophilicity compared to the annealed sample. After immersion in SBF, specimens were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD) methods. More amount of white precipitates composed of hydroxyapatite and magnesium phosphate along with magnesium hydroxide was observed on the surfaces of groove pressed specimens as compared to the annealed specimens with an increase in immersion time in SBF. Corrosion behavior of the samples estimated using potentiodynamic polarization curves indicate good corrosion resistance for GPed samples before and after immersion in SBF. The MTT assay using rat skeletal muscle (L6) cells revealed that both the processed and unprocessed samples are nontoxic and cell adhesion was promising for GPed sample.     

Recommendations for Family Interventions Following a Suicide.

Consistent with a culturally competent, developmentally informed, and gender-sensitive integrative model of family therapy, this article provides a framework for therapists working with families following the suicide of a loved one. Recommended clinical interventions are provided and organized around commonly encountered themes: addressing psychological distress and painful affects, understanding denial as a protective coping strategy, appreciating and managing concerns about family disintegration, helping families deal with stigmatization, and creating a suicide story. Clinical vignettes highlight common challenges faced by families in response to a loved one's suicide. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Travel-time models for flow-rack automated storage and retrieval systems

In this paper, closed-form travel-time expressions for flow-rack automated storage and retrieval systems are developed. The expressions, which are based on a continuous approach, are compared for accuracy, via simulation, with exact models which are based on a discrete approach. There is no significant difference between the results obtained from the continuous-approach-based closed-form expressions and the ones from the discrete-approach-based exact solutions. The closed-form expressions are easy to calculate due to their simplistic forms, even without a computer, while the exact solutions are extremely complex. On the basis of computation time, the proposed closed-form expressions are extremely practical when compared with the discrete-approach-based expressions, which require extensive computation time. The closed-form travel-time expressions developed in this study can be used to (1) establish performance standards for existing AS/RS, (2) evaluate throughput performance for flow-rack AS/RS alternative design configurations, and (3) compare different storage techniques for improved system performance. Due to their simplistic, yet accurate, definitions, the closed-form expressions, as well as the results of this study, are applicable to industry.     

Comparison of Single-Carrier and Multi-Carrier QAM System Performance in the Presence of Carrier Phase Jitter

In this contribution, we investigate how the carrier phase jitter of a phase-locked oscillator for IF-to-baseband conversion affects the performance of single-carrier QAM (SC-QAM) and multi-carrier QAM (MC-QAM); the considered multi-carrier system is of the OFDM (orthogonal frequency-division multiplexed) type. This phase jitter reduces the signal-to-noise ratio (SNR) at the input of the decision device, and therefore gives rise to an increase of the bit error rate. We show that, for a given jitter variance, SC-QAM and MC-QAM yield the same SNR degradation. However, when the synchronization for MC-QAM is derived from a pilot tone, we point out that the resulting jitter variance is considerably larger than for SC-QAM, in which case MC-QAM is degraded much more than SC-QAM.     

Influence of Chemical Composition on the Bioactivity of Spray Pyrolyzed Mesoporous Bioactive Glass

SiO₂‐CaO‐P₂O₅‐based mesoporous bioactive glass (MBG) is a potential material for bone implants due to its superior bioactivity. Sol‐gel is a common technique for preparing MBG. Early studies showed that for MBG, the composition and surface area have critical influences on the bioactivity of MBG. However, there is a counteractive effect if both factors are used to enhance the bioactivity of MBG: a higher Ca content (lower Si content) provides more nonbridging oxygen groups, which enhance the bioactivity, but a higher Ca content also allows a lower viscosity at high temperature. Low viscosity is not able to prevent the MBG liquid flowing into the mesopores and results in the reduction of the surface area, which deteriorates the bioactivity. Unlike sol‐gel, spray pyrolysis (SP) offers a rapid cooling rate, which can avoid the lower viscosity and resultant damage to the mesoporous structure, and the rapid cooling rate also preserves more metastable siloxane groups, which enhance the bioactivity. In this study, MBG particles with various Si:Ca ratios were synthesized using SP, and the morphology and bioactivity were investigated. Two typical morphologies, spherical mesoporous and wrinkled mesoporous, were observed. Also, a faster hydroxyl apatite formation time was observed in MBG with lower silica concentration (70 mol% SiO₂).     

Controlled surface topography of nanostructured particles prepared by spray‐drying process

Nanostructured particles (clusters) with complex and periodic topography at the microscopic scale show unique structural patterns. Hence, good properties should be obtained when the surface topography of such clusters, especially those containing nanoparticles (NPs) of different sizes, can be carefully tuned. The coffee‐ring structure is one of the most interesting structures for catalyst and photonic crystal applications or porous particle molds. Here, well‐defined clusters with a coffee‐ring structure were prepared by spray drying. The complexity of the NP distribution in the resulting two‐ and three‐component systems is discussed. A better understanding of how finite groups of different NPs self‐organize in a moving droplet to form a confined geometry may aid in controlling the structure of matter at multiple length scales. Interestingly, the configuration of the large microsphere clusters was found to be influenced by the presence of the small particles, which formed a ring‐like structure. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1503–1511, 2017