Effect of nafion membrane thickness on performance of vanadium redox flow battery

The performance of vanadium redox ow batteries (VRFBs) using different membrane thicknesses was evaluated and compared. The associated experiments were conducted with Nafion® 117 and 212 membranes that have 175 and 50 μm of thickness, respectively. The charge efficiency (CE) and energy efficiency (EE) of VRFB using Nafion® 117 were higher than those of VRFB using Nafion® 212, while power efficiency was vice versa. In terms of amounts of charge and discharge that are measured in different charging current densities, the amounts in VRFB using Nafion® 212 are more than that in VRFB using Nafion® 117. To further characterize the effect of membrane thickness on VRFB performance, electrochemical impedance spectroscopy (EIS) and UV-vis. spectrophotometer (UV-vis) were used. In EIS measurements, VRFB using Nafion® 117 was more stable than that using Nafion® 212, while in UV-vis measurements, vanadium crossover rate of VRFB usingNafion® 212 (0.0125M/hr) was higher than that of VRFB using Nafion® 117 (0.0054 M/hr). These results are attributed to high crossover rate of vanadium ion in VRFB using Nafion® 212. With these results, vanadium crossover plays more dominant role than electrochemical reaction resistance in deciding performance of VRFB in condition of different membranes.     

Receptors of sex pheromones and abstinons inMusca domestica andGlossina morsitans

Receptors arranged in two pairs on the inner and outer sides of the proximal end of the tibia of legs ofMusca domestica L. andGlossina morsitans morsitans Westwood are described here for the first time. In the male fly, these receptors function in perception of sex pheromones, as demonstrated in experiments in which the sense organs were coated with paraffin. Similar techniques showed that sense organs for abstinon are located on the tarsi. Scanning electron microscopy and light microscopy show that the tibial sense organs ofMusca may be sensilla of the coeloconic type.     

Gossypol analysis in cottonseed oil by HPLC

Gossypol in cottonseed oil was selectively separated by the extraction of cottonseed oil with a hexane and N,N dimethyl formamide:water (2∶1, v/v) solvent mixture. After filtration, the extract was injected into the HPLC with the elution time less than 15 min. The spectrophotometric method showed 2 to 5 times higher values of gossypol content in different types of glanded cottonseed oil than did the HPLC method. This is probably due to the gossypol derivatives and coloring interferences reacting with p-anisidine to develop color and increasing the absorbance reading, whereas gossypol was separated and detected in the HPLC method.     

Synthesis of EPDM-g-MAN by suspension graft copolymerization and its toughening effect on SAN resin

Suspension graft copolymerization of methyl methacrylate and acrylonitrile onto ethylene–propylene–diene terpolymer (EPDM) was carried out under different reaction conditions. A series of graft products of EPDM-graft-methyl methacrylate and acrylonitrile (EPDM-g-MAN), characterized by Fourier-transform infrared spectroscopy, was blended separately with styrene–acrylonitrile (SAN) resin to investigate their toughening effect on SAN matrix. The relationship between the polarity of EPDM-g-MAN and toughness of EPDM-g-MAN/SAN resin blends (AEMS) was evaluated. The compatibility and morphologies of AEMS were probed by dynamic mechanical analysis, transmission electron microscopy, and scanning electron microscopy to determine the toughing mechanism of the blends. Thermogravimetry results showed that the thermal stability of AEMS was enhanced with the incorporation of EPDM-g-MAN graft copolymer.     

Rapid analysis of dimer acid by HPLC/FID

A method was developed for the rapid analysis of polymerized fatty acids (dimer acid) using normal phase HPLC with a flame ionization detector (FID). The use of analytical scale HPLC with the FID is a significant limprovement over existing methodology for dimer analysis. The HPLC analysis takes only 25 min per sample, with no derivatization required. The FID response is linear for dimer samples from 10% to 90% monomer content. Absolute measurement precision is typically less than 0.5 area percent. Recovery of synthetic dimer blends averaged 102%. Results for the analysis of commercial dimer acid are comparable to those obtained using an HPLC/gravimetric method. The HPLC/FID method is applicable to the analysis of crude dimer as well as the finished dimer product.     

Electrospinning of chitosan/poly(lactic acid-co-glycolic acid)/hydroxyapatite composite nanofibrous mats for tissue engineering applications

Electrospinning, which is a fiber fabrication technique using electrical forces to produce fibers with diameters ranging from nanometers to several micrometers, can be used to prepare materials mimicking the extracellular matrix proteins for potential use as tissue engineering scaffolds. In this study, nanofibrous mats of chitosan (CH) and poly(lactic acid-co-glycolic acid) (PLGA) having fiber diameters between 167 to 525 nm, and containing hydroxyapatite (HAp), were prepared by electrospinning technique. Morphological, chemical, thermal and degradation tests and cell affinity tests were carried out. Chitosan mats were stable in aqueous media and showed degradability in the presence of lysozyme. In PBS solution, PLGA mats disintegrated completely in 2 weeks. Meanwhile, CH-PLGA mats containing equal amounts of both CH and PLGA fibers and CH-PLGA-HAp samples containing 20 % HAp lost 50 and 40 % of their initial weight in 4 weeks, respectively. Cell culture tests showed that all electrospun fibrous mats promoted SaOs-2 cell attachment and proliferation. However, cell proliferation on CH-PLGA-HAp fibrous mats was higher compared to the others after 7 days demonstrating the positive effect of HAp on cell affinity properties compared to pristine CH or PLGA fibrous scaffolds.     

Reversible addition-fragmentation chain transfer polymerization of vinyl acetate and vinyl pivalate in supercritical carbon dioxide

Two highly supercritical CO₂-soluble, poly(vinyl acetate) (PVAc)-based macro-reversible addition-fragmentation chain transfer (RAFT) agents were synthesized. The RAFT agents were used for the first time in RAFT/macromolecular design via the interchange of xanthates (MADIX) and polymerization of vinyl acetate (VAc) and vinyl pivalate (VPi) in supercritical carbon dioxide (scCO₂). A homopolymer PVAc and a block copolymer PVAc-b-PVPi made by RAFT/MADIX polymerization were characterized, and the effects of time and RAFT agents on polymerization were examined. For the 8.4 wt% RAFT agent in VAc, the molecular mass (M _n ) of homopolymer PVAc was 26,000 g mol^?1 and PDI was 1.35. For the copolymerization of VPi using 9.8 wt% PVAc-RAFT agent in VPi for 24 h, the M _n and PDI of PVAc-b-PVPi reached 32,400 g mol^?1 and 1.42, respectively. These results suggest that the polydispersity can be controlled during the clean production of PVAc and PVPi by RAFT/MADIX polymerization in scCO₂.     

Unsaturated fatty acids in the postnatally developing rat lung

Fatty acid desaturase activity specific for the C-9 position is present in lung microsomes prepared from rats of all ages. This activity is significantly lower in neonatal rat lung compared with adult lung. A rapid increase in C-9 fatty acid desaturase activity seen at the approximate time of weaning may be related to a decrease in the polyunsaturated fatty acid (PUFA) content of the diet as the rat begins to consume laboratory chow instead of mother's milk. The 900×g supernatant fraction of rat lung parenchymal cell homogenates is capable of incorporating linoleate, linolenate, and arachidonate into both triacylglycerols and phospholipids. Lung tissue from rats less than 20 days old incorporates these PUFA into phospholipids at a greater rate than lung, tissue from adult rats. The incorporation of these PUFA into phospholipids in neonatal lung tissue occured at a greater rate than their incorporation into triacylglycerols. In contrast, lung tissue from adult rats incorporated PUFA into triacylglycerols at a greater rate than into phospholipids. These data show that PUFA, known to be elevated in neonatal rat lungs, are used primarily for phospholipid biosynthesis in neonatal lung tissue whereas in adult lung tissue they are preferentially esterified to glycerol.     

Reaction of fatty acids with 3,3′-iminobis-propylamine to produce soil hydrophobic agents

The reaction between two moles of fatty acid and one of 3,3′-iminobis-propylamine (DPTA) is somewhat analogous to the reaction between fatty acid and diethylenetriamine (DETA) that we had reported previously, but there are significant differences. Conversion to the diamide HN(CH₂CH₂CH₂NHCOR)₂ proceeds much more rapidly but less efficiently than does the reaction of fatty acid with DETA. The former diamide is obtained in only about a 70% yield and byproducts are obtained, whereas the reaction with DETA yields the diamide almost quantitatively. Cyclization to the pyrimidine $$RCONHCH_2 CH_2 CH_2 NCH_2 CH_2 CH_2 N = CR$$ is extremely slow and incomplete. The analogous cyclization of α,ω-diamides of DETA produces high yields of imidazolines. The AOCs wet method for amine titration gave erroneous structural information when the test was applied to the diamides of DPTA, as was the case for the DETA-diamide. The water repellency of soils treated with a homologous series of fatty iminobis-propylamine (DPTA)-diamides was studied, and the following observations were made: 1) the fatty DPTA-diamides were slightly more hydrophobic than the fatty DETA-diamides, which we ascribe to the additional methylene groups of the former; 2) hydrophobicity intensified with increasing molecular weight of the saturated fatty acids; and 3) unsaturation, as in the oleic derivative, enhanced hydrophilicity.     

Selected factors influencing neurohormonal regulation of sex pheromone production inHeliothis species

Sex pheromone production and release in females ofHeliothis species exhibit a diel periodicity. Phermone production is controlled by a hormone, the pheromone biosynthesis activating neuropeptide (PBAN). Release of PBAN to activate pheromone production follows a circadian rhythm. InH. zea females, mating terminates pheromone production. An unidentified hemolymph-borne factor is transferred from the male to the female during mating. It is speculated that this factor interacts with the release mechanism of PBAN to prevent further production of the pheromone following mating. Wild females ofH. phloxiphaga (reared from larvae collected in the field) did not produce or release the sex pheromone unless kept in association with the host plant. Pheromone production could be induced in these females by the injection of PBAN. It is suggested that a signal from the host plant is essential to trigger the release of PBAN to induce pheromone production.     

Preparation and characterization of a new polymer/pharmaceutical-based composite. Part I: Meloxicam

Composites of low-density polyethylene (LDPE), poly(ethylene-co-vinyl acetate) (EVA), poly(ethylene-co-octadecene), and an LDPE/EVA blend were prepared with different amounts of meloxicam (1, 3 and 5 wt %) by the melt blending process. Meloxicam was homogenously dispersed in polymer matrices. The polymer–meloxicam composites showed thermal behavior and thermal characteristics similar to those of the original polymers. Meloxicam release from the composites was examined in vitro for 50 days. The composites were incubated in phosphate-buffered solution and meloxicam concentration was determined by high-performance liquid chromatography. The prolonged release of the drug indicates that meloxicam-loaded plastic rings offer potential for control of reproduction and chronic inflammatory conditions.     

Quantitation of a bioactive metabolite in undisturbed rhizosphere—Benzyl isothiocyanate fromCarica papaya L.

A “continuous root exudate trapping system” was recently developed in this laboratory by which the allelopathic metabolites from the undisturbed rhizosphere ofHemarthria altissima (Poir.) Stapf. et Hubb. were collected. Twelve phenolic compounds were identified by capillary GC-MS (Tang and Young, 1982). In this report, we further describe its use for the quantitation of benzyl isothiocyanate (BITC), a highly bioactive volatile compound, in the rhizosphere of growing papaya plants. Samples were collected from 64 individual papaya (Carica papaya L.) trees of Waimanalo and Higgins cultivars. Hydrophobie compounds collected on XAD-4 columns were eluted with acetone and the levels of BITC were determined by a gas Chromatograph equipped with a sulfur-specific flame photometric detector. For 2-month-old trees, the rate of BITC released from the root system of Waimanalo was 2.03 ± 0.85μg/tree/day. From Higgins, it was 2.36 ± 1.06 μg/tree/day. It has been reported that Waimanalo is resistant whereas Higgins is susceptible toPhytophthora palmivora Butl., the major root rot fungal pathogen of papaya trees in Hawaii. Our results lead us to conclude that the rate of BITC released alone cannot account for differences in the resistance of these two cultivars to the pathogen.     

Rheological behavior of a LDPE/PS/SBS blending melt

The dynamic rheological behaviors are measured by small amplitude oscillatory shear on a rotational rheometer for a low-density polyethylene (LDPE)/polystyrene (PS)/styrene–butadiene–styrene (SBS) block copolymer blend with the tool of cole–cole plot. The morphology of the blend is measured by scanning electron microscope (SEM) micrograph, the storage moduli–angular frequency (G′–ω) data are fit by the Palierne model, and the relaxation time spectrum is investigated. The storage modulus and loss modulus of the LDPE/PS/SBS blend at low frequency increase when the weight ratio LDPE/PS increases from 10/90, reaches a maximum of 30/70, and drops thereafter. The cole–cole plots of some blends (10/90/3, 70/30/3, 90/10/3 and 100/0/3) have only one main arc due to compatibilizing effect of the SBS, and those of other blends (0/100/3, 30/70/3 and 50/50/3) have a second arc or a long tail besides the main arc probably due to phase separation. The SEM micrographs of the LDPE/PS/SBS = 10/90/3, 30/70/3, 50/50/3 show sea-island, semi-co-continuous and co-continuous structure, respectively. G′–ω curve of two LDPE/PS/SBS = 30/70/3 and 50/50/3 blends shows a power law, and the power index is much lower than one (0.748 and 0.817), respectively, showing a co-continuous morphology also verified by the SEM micrographs. The experimental data of G′–ω curve of the LDPE/PS/SBS blends are fit by Palierne model, the deviation between the fit line and the experimental data increases gradually as the LDPE/PS weight ratio decreases from 90/10 to 10/90. For the LDPE/PS/SBS blends, the weighted relaxation spectra τH (τ)–τ show a main as well as a second arc or tail; the former corresponding to the relaxation of PS phase and the latter corresponding to that of LDPE phase. Due to the compatibilizing effect of SBS the relaxation time and spectrum strength of LDPE/PS = 50/50 (wt) blends are both increased.     

Study on compatibility of recycled polypropylene/high-density polyethylene blends using rheology

The compatibilization of recycled polypropylene (PP) and high-density polyethylene (HDPE) was studied using two types of compatibilizers: 5 wt% PP-grafted-maleic anhydride (5 wt% MAPP) and 5 wt% HDPE-grafted-maleic anhydride (5 wt% MAHDPE), using a cone and plate rheometer. Maleic anhydride (MAH) was grafted onto PP or HDPE via peroxide initiated melt grafting technique. Blends containing highest amount of pure HDPE exhibited maximum values for tensile strength, complex viscosity, dynamic and loss modulus compared to similar blends developed using recycled HDPE. The latter properties of all the compatibilized blends were higher compared to that of uncompatibilized blends. Studies on rheology of the pure and recycled polymer and its compatibilized blends have thrown some light on the molecular weight distribution of these materials. High shear yielding characteristics were noted for MAHDPE compatibilized blends containing high percentage of HDPE. Scanning electron microscopy showed that blends containing a high percentage of HDPE and HDPE based compatibilizer exhibit a dispersed morphology. Fourier transform infrared spectrometer characterization was conducted to check if compatibilization occurred between recycled PP and HDPE.     

The antioxidant activity of amino acids in two vegetable oils

Of 27 amino acids studied, most had some antioxidant activity when added in aqueous solution to either safflower oil or a mixture of sunflower and cottonseed oil (active oxygen and storage methods). Cysteine-HCl, glutamic acid-HCl (in the mixture), and glutamic acid-HCl (in safflower oil) behaved as prooxidants. When added as a solid, most amino acids were ineffective. The protection factors of these amino acids were less than 1.3 in safflower oil with methionine, proline, lysine and cysteine providing the highest activ-ity. In the oil mixture (which had a higher metal content) lysine, arginine, glutamic acid, methionine, and hydroxyproline were anti-oxidant with protection factors of up to 1.85. Chelation of metals by amino acids was presumably responsible for the antioxidant activity. The increase in cysteine concentration up to 1% has more than doubled the protection factor in Bint oil (compared with the 0.01% level), whereas with some other amino acids the increase was either small or slight.     

The effect of loading on sintering and catalytic activity of Pt/SiO2 hybrid catalyst powders synthesized via spray pyrolysis

Platinum (Pt) is commonly used as a heterogeneous catalyst to effectively convert carbon monoxide (CO) from automobile exhaust gas into carbon dioxide (CO₂). Platinum/silica (Pt/SiO₂) hybrid catalyst powders with varying Pt content were synthesized via a spray pyrolysis process. The average particle size and specific surface area of the Pt nanoparticles on the Pt/SiO₂ hybrid catalyst powders were characterized as-prepared and after heat treatment. As the Pt loading increased, the Pt nanoparticles grew on the surface of the SiO₂ as a result of sintering, and the catalytic efficiency decreased. This work demonstrates that the Pt/SiO₂ (4 wt% Pt) hybrid catalyst powder is suitable as a hightemperature automobile exhaust catalyst, compared with the Pt/SiO₂ hybrid catalyst powder with high Pt loading (14 wt% Pt), indicating that metal nanoparticle loading is a key factor for determining catalytic activity.     

A new method to construct hierarchical ZSM-5 zeolites with excellent catalytic activity

Desilicication and dealuminzation with weak alkaline solution and acid liquor is an effective way to construct hierarchically mesoporous without damaging its crystallinity and preserving its acidity in ZSM-5 zeolites. We investigated the influence of the concentration of NaAlO₂, treatment time, temperature and the concentration of HCl on the crystallinity of ZSM-5 and characterized the products with XRD, SEM, XRF, BET, NH₃-TPD, etc. The results showed that the appropriate concentration of NaAlO₂ solutions extract selectively silicon from the framework of the zeolites while a small portion of aluminum would patch some parts of vacancies produced by the removal of silicon, then the HCl would dealuminize to maintain the SiO₂/Al₂O₃ ratios, which preserved the crystallinity of ZSM-5 perfectly. Furthermore, the micro-reaction activity tests displayed that the obtained products had higher catalytic than the parent zeolites because of their optimized hierarchical micro-mesoporous.     

Effects of in situ and ex situ formations of silica nanoparticles on polyethersulfone membranes

This study deals with the observed changes in the structure and performance of polyethersulfone (PES) membranes due to in situ formation and ex situ addition of silica particles (SiO₂). Hydrolysis and condensation of tetraethyl orthosilicate (TEOS) inside the PES polymer matrix and the reaction of TEOS with ammonium hydroxide were chosen to form in situ and ex situ SiO₂ formations, respectively. The resultant structure confirmed by X-ray diffraction for the composite PES membranes showed the retention of the amorphous nature even after the addition of SiO₂. The FTIR study revealed the functional groups corresponding to silica networks with enhanced OH signatures on the surface of the composite membranes. Field emission scanning electron microscopic images showed the variation in the surface and cross-sectional structures for the pure and composite membranes. Considerable reduction in the thickness of the skin, difference in the pore structure and ‘finger-like’ cross-sectional morphology with the presence of SiO₂ was observed in PES membranes. Both SiO₂/PES composite membranes were showed a minor change in their glass transition temperature (T _g). The ex situ methodically formed composite membrane displayed an increase in the pure water flux and decrease in bovine serum albumin rejection as compared to in situ and pure PES membranes. These kinds of composite membranes can be utilized for water treatment applications demanding higher water flux.     

Lipids in chinese medicine. Characterization of allcis 5,11,14,17-eicosatetraenoic acid inBiota orientalis seed oil and a study of oxo/furanoid esters derived fromBiota oil

The fatty acid composition ofBiota orientalis seed oil consists of palmitic (5.1%), stearic (3.4%), oleic (15.3%), linoleic (25.6%), linolenic (34.7%), C20:3(11c,14c,17c) 4.9%, and C20:4(5c,11c,14c,17c) 10.5%. The unsaturated fatty esters derived fromBiota oil were epoxidized and subsequently treated with NaI-PrI-DMSO. Chromatographic separation of the complex product mixture revealed the presence of C18-oxo, C18-furanoid, and C18-and C20-oxo-furanoid esters. Epoxidation of a pure sample of C20:4(5c,11c,14c,17c) followed by NaI-PrI-DMSO treatment gave a mixture of C20-dioxo-furanoid esters. The positions of the oxo and furanoid groups in the various derivatives were determined by GC/MS analysis.     

Occurrence of 2,6-dichlorophenol in hard ticks,Hyalomma dromedarii andHyalomma anatolicum excavatum,and its role in mating

2,6-Dichlorophenol (2,6-DCP) is the major volatile sex pheromone component in the extracts ofHyalomma dromedarii (35 ng/female) andHyalomma anatolicum excavalum (20 ng/female). The GC fraction containing essentially pure 2,6-DCP, as well as an equal amount of synthetic 2,6-DCP, elicits from the male of each species a hierarchy of responses culminating in attempted copulation.