Antifungal activity of five different essential oils in vapour phase for the control of Colletotrichum gloeosporioides and Lasiodiplodia theobromae in vitro and on mango

Mango fruit has high commercial value; however, major postharvest losses are encountered throughout the supply chain due to postharvest diseases. These results lead to the search for natural fungicide for postharvest diseases control. The antifungal effects of five essential oils (thyme, clove, cinnamon, anise and vitex) were assessed by disc volatilisation method. Thyme oil vapours at 5 μL per Petriplate, and clove and cinnamon oil at 8 μL per Petriplate showed 100% growth inhibition of mango pathogens in vitro. GC/MS analysis of essential oil showed thymol (23.88), o‐cymol (23.88) and terpinolene (23.88) as the major constituents of thyme oil. Clove and cinnamon oils contain 3‐allyl‐2‐methoxyphenol (37.42%) and benzofuran 3‐methyl (17.97%), respectively. Thyme oil as a fumigant at 66.7 μL L^?1 showed a significant (P < 0.05) inhibition on postharvest pathogens of mango fruits stored at 25 °C for 6 days. Results of our study suggest the possibility of using thyme oil as an alternate natural fungicide to manage postharvest diseases in mango.     

Single-electron transfer living radical copolymerization of SWCNT-g-PMMA via graft from approach

The sidewall functionalization of single-walled carbon nanotubes (SWCNTs) was established by poly (methyl methacrylate) (PMMA) using controlled radical polymerization (CRP) method. A bromide functionalized SWCNT (SWCNT-Br) has been used as an initiator for the synthesis of SWCNT-graft-PMMA (SWCNT-g-PMMA). The efficiency of the sacrificial initiator (S) was monitored during the polymerization process. The obtained polymers possess a uniform distribution of molecular weight with a lower polydispersity index of 1.36. The SWCNTs-based initiator acts as an efficient medium for the controlled growth of polymer on the SWCNTs surfaces. The presence of bimodal gel permeation chromatographic (GPC) curve for the SWCNT-g-PMMA(S) obtained through sacrificial initiator (S) confirms uncontrolled behavior. However, the clear sharp peak for SWCNT-g-PMMA obtained without sacrificial initiator shows its well-controlled process of polymerization, which acts as a mimic to bone cement. The efficiency of the functionalization of SWCNT and the controlled formation of SWCNT-g-PMMA composites were characterized by TGA, Raman, TEM, NMR, XPS and dispersion measurements.     

Antioxidant capacity and phenolic content of different solvent extracts from banana (Musa paradisiaca) and mustai (Rivea hypocrateriformis)

In the present study, chloroform, acetone, and methanol extracts from stem and flower of banana (Musa paradisiaca) and leaves, stem, and flowers of mustai (Rivea hypocrateriformis) were evaluated for their in vitro antioxidant activity using ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH^•), 2,2′azinobis (3-ethylbenzothiozoline-6-sulfonic acid) diammonium salt (ABTS^•+), iron chelation, and antihemolytic activity. Among the solvents used, methanol gave the maximum yield in banana, whereas in night glory acetone was reported to having higher extractive value. The total phenolic content was also higher in these extracts. The antioxidant potential of the extracts was well established with their DPPH^• and ABTS^•+ radical scavenging activities and ferric reducing antioxidant capacity. The potential of multiple antioxidant activity of samples can be further evidenced by inhibition of reactive oxygen mediated erythrocyte cell lysis and metal ion chelating activity. However, this is the first report on the antioxidant property of mustai and this plant is having excellent antioxidant potential over banana. In conclusion, the results implied that the leaves, stem, and flowers of banana, and mustai could be considered as health supplements and nutraceuticals/functional foods.     

Measurement of segregation and distribution coefficients in MAR-M200 and hafnium-modified MAR-M200 superalloys

Crystals of the MAR-M200* and the Hf-modified MAR-M200 superalloys were grown by plane front solidification. The solidification microstructures of both alloys contain the proeutectic γ phase, the γ + γ’ eutectic, and a 3-phase eutectic. The chemical compositions of these alloys were measured along the growth direction with the use of an electron microprobe. In the MAR-M200 alloy, W preferentially segregates to the proeutectic while Ti, Cr, and Al preferentially segregate to the eutectic. In the Hf-modified MAR-M200 alloy, W, Cr, and Al preferentially segregate to the proeutectic while Ti and Hf preferentially segregate to the eutectic. The segregation trends observed in the plane front solidified alloys are generally in agreement with the results reported in the literature for the dendritically solidified alloys. The distribution coefficients determined from the composition data range from 1.1 to 1.3 for W, 0.5 to 0.7 for Ti, 0.85 to 0.95 for Al, and 0.9 to 0.95 for Cr in the MAR-M200 alloy, and from 1.1 to 3.7 for W, 0.8 to 1.2 for Ti, 0.95 to 1.2 for Al, and 0.17 to 0.29 for Hf in the Hf-modified MAR-M200 alloy.     

Antioxidant activity of the differentially processed seeds of Jack bean (<Emphasis Type="Italic">Canavalia ensiformis</Emphasis> L. DC)

Antioxidant activity of 70% acetone extracts of raw and processed seeds of Jack bean (Canavalia ensiformis L. DC) was evaluated by various in vitro antioxidant assays, including total antioxidant, free radical scavenging, reducing power, metal ion chelating, β-carotene/linoleic acid bleaching, and antihemolytic activities. The total phenolics and tannin contents were higher in the extract of seeds processed by autoclaving with 1% ash solution (3.2 and 1.6 g/100 g extract, respectively). In general, all the extracts of processed seeds exhibited higher activity in various antioxidant systems, when compared to raw seeds but significant differences were noticed between processing methods. The extract of seeds autoclaved with 1% sugar solution showed higher DPPH radical scavenging activity (IC₅₀ 10.6 mg/mL). Interestingly, the extract of dry heated seeds registered higher inhibition of hemolysis (76.1%) compared to standards butylated hydroxyanisole (BHA) (66.2%) and α-tocopherol (59.3%) at the concentration of 500 μg/mL.     

Effect of fluid flow and hafnium content on macrosegregation in the directional solidification of nickel base superalloys

Nickel base superalloys of the MAR-M200 type with additions of hafnium from 0 to 2.6 pct were directionally solidified in investment molds with an abrupt change in cross-section. Segregation patterns of several alloying elements (Hf, W, Ti, and Co) were determined and related to partition ratios, hafnium content, and casting geometry. The segregation is more pronounced near the section change, and hafnium substantially increases the segregation tendency of these alloying elements. Variation in eutectic volume percent was related to the observed macrosegregation. A model based on the flow of interdendritic liquid to feed solidification shrinkage was Actapted to describe the macrosegregation behavior of these complex superalloys. The model accurately predicts the effect of casting geometry on macrosegregation.     

New synthesis and characterization of ionic polyurethane-urea liquid crystals

A new series of thermotropic ionic polyurethane-urea (PUU) liquid crystals (LCs) were synthesized, each by using the corresponding diisocyanate, 4,4′-bis(6-hydroxyhexoxy)biphenyl, and sodium 2,5-diaminobenzenesulfonate. Morphology, phase transition temperatures, and spectroscopic characteristics of the PUU LCs are reported. Each PUU exhibits a monotropic liquid crystal phase upon slow cooling. The PUU LC phase texture is visible by polarized optical microscopy (POM) and is dependent upon the PUU isocyanate precursor; 1,6-diisocyanatohexane (HDI) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3,-trimethylcyclohexane (IPDI) polymers have schlieren textures, whereas 2,4-diisocyanato-1-methylbenzene (TDI) and methylenebis(4-phenylisocyanate) (MDI) polymers show grain textures.     

Ionomer covalent functionalization of single‐walled carbon nanotubes by radical polymerization of zirconium acrylate

A facile and efficient covalent functionalization of single‐walled carbon nanotubes (SWCNTs) via peroxide‐mediated free radical covalent attachment and polymerization of zirconium acrylate is reported. The resulting covalently functionalized SWCNTs exhibit improved solubility in organic solvents. The covalently functionalized SWCNTs are characterized by cross polarization magic angle spinning ¹³C NMR, differential scanning calorimetry, thermogravimetric analysis, x‐ray diffraction, Raman, and infrared spectroscopy. Infrared spectroscopy reveals that carboxylate groups of covalently attached ionomers chelate with zirconium ions and the participating carboxylate groups may be from different ionomer chains leading to cross‐linking the chains. The SWCNT topology, ionic clustering, and π‐electron clouds were explored by transmission electron microscopy. © 2014 American Institute of Chemical Engineers AIChE J, 60: 820–828, 2014