Preparation and performance of alumina/epoxy-siloxane composites: A comparative study on thermal- and photo-curing process.

Although epoxy-based composites that consist of inorganic fillers and matrixes are widely used in "conventional" electronic packaging applications due to their excellent insulation and robust properties, they limit their uses in "advanced electronic packaging" which requires enhanced thermal conductivity. However, conventional thermal curing methods for fabrication of epoxy-based composites do not fulfill sufficient thermal conductivity. Herein, we apply photo-induced curing strategy for fabricating alumina-incorporated epoxy-siloxane composites that consist of sol-gel derived siloxane matrix and bimodal sized alumina particles as a thermally conductive filler. We investigate how curing mechanism (thermal- or UV-curing) and varying the ratios of the alumina particles of two different sizes affect the various physical properties. It is found that photo-curing process makes greatly enhanced thermal conductivity, low thermal expansion, and high mechanical robustness compared to thermally-cured composites. As the results, we can achieve significantly enhanced thermal conductivity (>11 W/m K) with high thermal stability and mechanical robustness.

Hydrogen production by electrochemical reaction using ethylene glycol with terephthalic acid.

In this study, ethylene glycol (EG) and terephthalic acid (TPA) were used to generate hydrogen using copper electrodes in an alkaline aqueous solution and the corresponding reaction mechanism was experimentally investigated. Both EG and TPA produced hydrogen; however, TPA consumed OH-, inhibiting the production of intermediary compounds of EG and causing EG to actively react with H2O, ultimately leading to enhanced hydrogen production. In addition, the initiation potential of water decomposition of the EG and TPA alkaline aqueous solution was 1.0 V; when 1.8 V (vs. RHE) was applied, the hydrogen production reached 440 mmol L-1, which was substantially greater than the hydrogen production rate of 150 mmol L-1 during water decomposition.

Correction: Hydrogen production by electrochemical reaction using ethylene glycol with terephthalic acid.

[This corrects the article DOI: 10.1039/D0RA10187G.].

Reverse electrodialysis (RED) using a bipolar membrane to suppress inorganic fouling around the cathode.

When operating reverse electrodialysis (RED) with several hundreds of cell pairs, a large stack voltage of more than 10 V facilitates water electrolysis, even when redox couples are employed for the electrode reaction. Upon feeding natural water containing multivalent ions, ion crossover through a shielding membrane causes inorganic scaling around the cathode and the interior of the membrane stack, due to the combination with the hydroxide ions produced via water reduction. In this work, we introduce a bipolar membrane (BPM) as a shielding membrane at the cathode to suppress inorganic precipitation. Water splitting in the bilayer structure of the BPM can block the ions diffusing from the catholyte and the feed solution, maintaining the current density. To evaluate the effect of the BPM on the inorganic precipitates, diluted sea salt solution is allowed to flow through the outermost feed channel near the cathode, in order to maintain as large a stack voltage as possible, which is important to induce water splitting in the BPM when incorporated into an RED stack of 100 cell pairs. We measure the electric power of the RED according to the arrangement of the BPM and compare it with that of conventional RED. The degree of inorganic scaling is also compared according to the kind of shielding membrane used (anion exchange membrane, cation exchange membrane, and BPM (Neosepta or Fumasep)). The BPM (Neosepta) shows the best performance for suppressing the formation of precipitates. It can hence be used to design a highly stable electrode system for long-term operation of a large-scale RED feeding natural water.

Assessing the behavior of the feed-water constituents of a pilot-scale 1000-cell-pair reverse electrodialysis with seawater and municipal wastewater effluent.

Reverse electrodialysis (RED) has vast potential as a clean, nonpolluting, and sustainable renewable energy source; however, pilot-scale RED studies employing real waters remain rare. This study reports the largest RED (1000 cell pairs, 250 m2) with municipal wastewater effluent (1.3-5.7 mS/cm) and seawater (52.9-53.8 mS/cm) as feed solutions. The RED stack was operated at a velocity of 1.5 cm/s and the pilot plant produced 95.8 W of power (0.38 W/m2total membrane or 0.76 W/m2cell pair). During operation of the RED, the inlet design of the stack, comprising thin spacers, and the water dissociation reaction at the cathode were revealed as vulnerabilities of the stack. Specifically, pressure drops at the fluid inlet parts had the most detrimental effects on power output due to clogged spacers around the inlet parts. In addition, precipitates resulting in inorganic fouling were inevitable during the water dissociation reaction due to significant potential generated by the stack in the cathode chamber. Na+ and Cl- accounted for the majority of ions transferred from seawater to wastewater effluent through ion exchange membranes (IEMs). Moreover, some divalent cations in seawater, Mg2+ and Ca2+, were also transferred to the wastewater effluent. Some organics with relatively low molecular weights in the wastewater effluent passed through the IEMs, and their hydrophobic properties elevated the specific UV absorbance (SUVA) level in the seawater.

High production of CH4 and H2 by reducing PET waste water using a non-diaphragm-based electrochemical method.

In recent years, the worldwide use of polyethylene terephthalate (PET) has increased exponentially. PET wastewater contains ethylene glycol (EG) and terephthalic acid (TPA). In this study, we present a unique method for producing combustible gases like CH4 and H2 from PET wastewater by electrochemical reaction of EG and TPA. The non-diaphragm-based electrochemical (NDE) method was used to treat PET wastewater. The electrochemical removal of EG and TPA from PET wastewater was examined and the optimal conditions for their reduction to CH4 and H2 were determined. Using the proposed system, 99.9% of the EG and TPA present in the PET wastewater samples were degraded to produce CH4 and H2, at applied voltages lower than 5 V. The highest Faradaic efficiency achieved for EG and TPA reduction was 62.2% (CH4, 25.6%; H2, 36.6%), at an applied voltage of 0.8 V. Remarkably, CH4 was produced from EG decomposition and H2 from TPA decomposition. To the best of our knowledge, this is the first reported instance of CH4 and H2 production from EG and TPA, respectively. The electrochemical reductive treatment will be an important discovery for reducing water contamination and replacing fossil fuels with respect to generating green energy.

Molecular and morphological data reveal hybrid origin of wild Prunus yedoensis (Rosaceae) from Jeju Island, Korea: implications for the origin of the flowering cherry.

PREMISE OF THE STUDY: The subgenus Cerasus of the genus Prunus includes several popular ornamental flowering cherries. Of the hundreds of cultivars, P. ×yedoensis ('Somei-yoshino') is the most popular and familiar cultivar in Korea and Japan and is considered to be of hybrid origin. However, the hybrid origin of P. ×yedoensis and its relationship to wild P. yedoensis, naturally occurring on Jeju Island, Korea, are highly controversial. METHODS: We extensively sampled wild P. yedoensis, cultivated P. ×yedoensis, and numerous individuals from other species belonging to subgenus Cerasus on Jeju Island. Samples from 71 accessions, representing 13 species and one cultivar (P. ×yedoensis), were sequenced for nrDNA ITS/ETS (952 characters) and seven noncoding cpDNA regions (5421 characters) and subjected to maximum parsimony and maximum likelihood analysis. Additive polymorphisms in the ITS/ETS regions were confirmed by cloning amplicons from representative species. KEY RESULTS: The nuclear (ITS/ETS and G3pdh) and cpDNA data, along with several morphological characteristics, provide the first convincing evidence for the hybrid origin of wild P. yedoensis. The maternal parent was determined to be P. spachiana f. ascendens, while the paternal parent was unresolved from the taxonomically complex P. serrulata/P. sargentii clade. The presence of two kinds of ribotypes was confirmed by cloning, and the possible origin of cultivated P. ×yedoensis from wild populations on Jeju Island was also suggested. CONCLUSIONS: Bidirectional and multiple hybridization events were responsible for the origin of wild P. yedoensis. Extensive gene flow was documented in this study, suggesting an important role of reticulate evolution in subgenus Cerasus.

DNA barcoding of Orchidaceae in Korea.

Species of Orchidaceae are under severe threat of extinction mainly due to overcollection and habitat destruction; accurate identification of orchid species is critical in conservation biology and sustainable utilization of orchids as plant resources. We examined 647 sequences of the cpDNA regions rbcL, matK, atpF-atpH IGS, psbK-psbI IGS and trnH-psbA IGS from 89 orchid species (95 taxa) and four outgroup taxa to develop an efficient DNA barcode for Orchidaceae in Korea. The five cpDNA barcode regions were successfully amplified and sequenced for all chlorophyllous taxa, but the amplification and sequencing of the same regions in achlorophyllous taxa produced variable results. psbK-psbI IGS showed the highest mean interspecific K2P distance (0.1192), followed by matK (0.0803), atpF-atpH IGS (0.0648), trnH-psbA IGS (0.0460) and rbcL (0.0248). The degree of species resolution for individual barcode regions ranged from 60.5% (rbcL) to 83.5% (trnH-psbA IGS). The degree of species resolution was significantly enhanced in multiregion combinations of the five barcode regions. Of the 26 possible combinations of the five regions, six provided the highest degree of species resolution (98.8%). Among these, a combination of atpF-atpH IGS, psbK-psbI IGS and trnH-psbA IGS, which comprises the least number of DNA regions, is the best option for barcoding of the Korean orchid species.

Effect of the carrier gas flow rate on the microstructure evolution and the generation of the charged nanoparticles during silicon chemical vapor deposition.

The generation of charged nanoparticles in the gas phase has been continually reported in many chemical vapor deposition processes. Charged silicon nanoparticles in the gas phase were measured using a differential mobility analyzer connected to an atmospheric-pressure chemical vapor deposition reactor at various nitrogen carrier gas flow rates (300-1000 standard cubic centimeter per minute) under typical conditions for silicon deposition at the reactor temperature of 900 degrees C. The carrier gas flow rate affected not only the growth behavior of nanostructures but also the number concentration and size distribution of both negatively and positively charged nanoparticles. As the carrier gas flow rate decreased, the growth behavior changed from films to nanowires, which grew without catalytic metal nanoparticles on a quartz substrate.

Formation of tetrapod-shaped nanowires in the gas phase during the synthesis of ZnO nanostructures by carbothermal reduction.

We experimentally confirmed that charged ZnO nanoparticles were generated abundantly in the gas phase using a differential mobility analyzer (DMA). When they were size-selected by the DMA and captured on a grid for transmission electron microscopy, particles of 10 nm had a rod or tetrahedron shape, while particles larger than 10 nm tended to have a tetrapod shape. The tetrahedral particles seemed to be a seed for the growth of tetrapod nanowires. Although the growth of a tetrahedron shape enclosed by a close-packed plane (0002) of the hexagonal close-packed ZnO can be explained by the classical crystal growth theory, the growth of tetrapod nanowires can be better explained by the building block of charged nanoparticles generated in the gas phase.

Tigliane diterpene esters with IFN γ-inducing activity from the leaves of Aleurites fordii.

Bioactivity-guided fractionation on the leaves of Aleurites fordii led to the isolation of a new tigliane diterpene ester, 12-O-hexadecanoyl-7-oxo-5-ene-16-hydroxyphorbol-13-acetate (1) along with four known compounds, 12-O-hexadecanoyl-7-oxo-5-ene-phorbol-13-acetate (2), 12-O-hexadecanoyl-phorbol-13-acetate (3), 12-O-hexadecanoyl-16-hydroxyphorbol-13-acetate (4), and 12-O-hexadecanoyl-4-deoxy-4α-16-hydroxyphorbol-13-acetate (5). The structures of these compounds were determined by interpretation of NMR (1D and 2D) spectroscopic data and MS data. All the isolates were evaluated for their effects on the induction of IFN-γ in NK92 cells. Compounds 3 and 4 exhibited the most potent responses in IFN-γ induction, comparable to the positive control, phorbol 12-myristate 13-acetate (PMA).

Flavonoids from the leaves of Litsea japonica and their anti-complement activity.

Four flavonoids, epicatechin (1), afzelin (2), quercitrin (3), and tiliroside (4), were isolated from the leaves of Litsea japonica (Thunb.) Jussieu (Lauraceae). The structures of compounds were identified by comparing their chemical and spectral data with those previously reported. The flavonoids (1-4) were tested for their anti-complement activity against classical pathway of complement system. Compounds 2-4 showed inhibitory activity against complement system with IC50 values of 258, 440, and 101 microm, respectively, whereas 1 was inactive. For the evaluation of the structure-activity relationship of 5,7-dihydroxyflavones, myricitrin (5) from Juglans mandshurica also tested for it's anti-complement activity and is inactive in this assay system. Furthermore, compounds 2, 3, and 5 were hydrolyzed with naringinase to give kaempferol (2a), quercetin (3a), and myricetin (5a), and these were also tested for their activity. Of the three aglycones, 2a exhibited anti-complement activity with an IC50 value of 730 microM, while 3a and 5a were inactive. The inhibitory potencies of 2, 2a, 3, 3a, 5, and 5a against complement activity increased in inverse proportion to number of free hydroxyls on B-ring of 5,7-dihydroxyflavone. Of the compounds tested, 4 showed the most potent inhibitory activity against the complement system.

Constituents from the stems of Actinodaphne lancifolia.

Two C(16)-lactonic compounds, actinolides A-B (1-2), were isolated from the stems of Actinodaphne lancifolia, together with five known lactones (3-7) and three known lignans (8-10). Their structures were determined spectroscopically, which included 2D NMR spectroscopic analysis.