Impacts of high-speed waterjets on web structures

Hydroentangling, where a fabric is formed by striking of fine, closely spaced, high speed waterjets, is one of the fastest growing bonding methods in the nonwoven industry. Softness, drape, conformability, and relatively high strength are the major characteristics that make this bonding technology unique. Despite the method appeal, few understand the impact of waterjet on fabric structures. The primary function of waterjet is to produce fiber entangling, which induces web integrity. In this paper, we have analyzed the interaction of waterjets on web structures to provide a better understanding of the hydroentangling mechanism. We have successfully visualized and analyzed structures of entangled regions through 2D and 3D imaging techniques. The influence of water-jet pressure, jet diameter, and number of jets on hydroentangled web structures is reported.     

Bioactive substance contents and antioxidant capacity of raw and blanched vegetables

Five commonly consumed vegetables in Malaysia namely, four-angled bean (Psophocarpus tetragonolobus D.C.), French bean (Phaseolus vulgaris L.), long bean (Vigna sesquipedalis L.), snow pea (Pisum sativum var. macrocarpon L.) and snap pea (Pisum sativum) were blanched in boiling water for 10 min. The contents of total phenolics, ascorbic acid and β-carotene, and the antioxidant capacity as typified by β-carotene and free radical scavenging activity (DPPH) assays were determined for the raw and blanched vegetables. The study revealed that blanching caused a significant (p < 0.05) increase in β-carotene content [fresh (389–539 µg/100 g), blanched (510–818 µg/100 g)], except in snow pea. Conversely, there was a significant (p < 0.05) decrease in ascorbic acid content [fresh (1.2–7.8 mg/100 g), blanched (0.67–3.8 mg/100 g)]. After blanching, the total phenolic content and antioxidant activity either decreased or increased depending on the type of vegetables. The total phenolic content was positively correlated with the antioxidant activity of the studied vegetables to some extent, but not with ascorbic acid or β-carotene.Industrial relevanceBeans (four-angled bean, French bean and long bean), and peas (snow and snap pea) are commonly consumed vegetables in Malaysia. However, the scientific information regarding blanching and its effect on the total phenolic content and antioxidant activities is very limited. This work showed that blanching caused an increase in the carotene, total phenolic content and antioxidant activities in some of the selected vegetables. This work is important since, consumption of raw vegetables does not have high nutritional qualities and antioxidant activities as shown in this work.     

Antioxidant and anticancer activities of 8-hydroxypsoralen isolated from wampee [Clausena lansium (Lour.) Skeels] peel

Fruits of wampee [Clausena lansium (Lour.) Skeels] contain a significant amount of coumarins with many health benefits. The activity-guided separation of an ethyl acetate-soluble fraction on a polyamide column followed by silica gel column and high performance liquid chromatography (HPLC) preparation afforded a pure compound, which was identified to be 8-hydroxypsoralen based on the ¹H, ¹³C NMR (nuclear magnetic resonance), and ESI-MS (electrospray ionisation mass spectrometric) analysis. This isolate exhibited good scavenging activities against DPPH radical and superoxide anion as well as significant reducing power. It also showed potent proliferation inhibitory activity against human hepatocellular liver carcinoma cell line (HepG2), human lung adenocarcinoma epithelial cell line (A549) and human cervical carcinoma cell line (HELA). This is the first report on the antioxidant and cytotoxic properties of C. lansium fruit extract. The food and pharmaceutical industry could be benefited by the usage of this extract containing this constituent.     

Effect of methylation on the structure and radical scavenging activity of polysaccharides from longan (Dimocarpus longan Lour.) fruit pericarp

Polysaccharides of longan fruit pericarp (PLFP) were purified by gel filtration chromatography and methylated by methyl iodide. The structure of methylated PLFP was identified by gas chromatography/mass spectrometry. The results indicated that the percentages of methylated Ara, Glc and Gal increased gradually to a maximal value with increasing volume of methyl iodide. Methylation resulted in a decrease in the DPPH radical scavenging activity of PLFP, while the superoxide anion radical scavenging activity of PLFP decreased with increasing the degree of methylation. When the degree of methylation reached up to 47.4% or a higher value, a promoted effect on the generation of superoxide anion was observed. Furthermore, a high correlation coefficient between degree of methylation and superoxide anion radical scavenging activity of PLFP was determined, which indicated the important role of hydroxyl groups of monosaccharide units in the radical scavenging activity of PLFP.     

Optical properties and surface morphology of near infrared multilayer antireflection coatings

Theoretical and experimental studies on multilayer antireflection (AR) coatings useful in the near infrared region, covering 1200 to 2000 nm are carried out, in which the relative merits and demerits of using a low refractive index magnesium fluoride (MgF₂), along with a high refractive index Substance H2 (Sub2) material of E. Merck, in comparison to silicon dioxide (SiO₂) and Sub2, are specifically investigated. It is seen that MgF₂ together with Sub2 produces wider band antireflection coatings, with lower ripple and integrated reflection loss (IRL), R^*, whereas SiO₂/Sub2 combination produces AR coatings with medium spectral coverage, and the coatings are free of structural defects, which in turn are highly durable against adverse environmental conditions.     

Effects of high-pressure treatment on the extraction yield, phenolic content and antioxidant activity of litchi (Litchi chinensis Sonn.) fruit pericarp

As a promising technique, high-pressure extraction (HPE) method was used to extract bioactive compounds from litchi fruit pricarp. The study involved in different experimental factors such as solvent, ethanol concentration (35-95, v/v), material to solvent ratio (1:25-1:100, w/v), acidic medium, extraction pressure (200-500 MPa), time (2.5-30 min) and temperature (30-90 °C). The extraction yield, total phenolic contents, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide anion scavenging capability of the HPE sample were examined and then compared with those of ultrasonic extraction and conventional extraction samples. The application of HPE obtained higher extraction yield compared to other extraction methods. However, there were no significant differences ( P  >   0.05) in the total phenolic content and the antioxidant activities among these various extractions. Compared with some conventional extraction method, the HPE exhibited higher extraction efficiency in terms of higher extraction yield and extraction time.     

Interaction of class A amphipathic helical peptides with phospholipid unilamellar vesicles

The exchangeable apolipoproteins are important in determining the structure/function properties of lipoproteins. These proteins typically contain varying amounts of amphipathic helices. Five model peptides, 18A, Ac-18A-NH2, Ac-18R-NH2, 37pA, and 37aA, have been designed to investigate variations of the amphipathic alpha-helix structural motif on their lipid-binding properties. These include the 18-residue peptides, 18A and Ac-18A-NH2, examples of class A helices, and Ac-18R-NH2, which has the positions of acidic and basic residues interchanged relative to 18A. Three larger peptides were also studied: 36A, a dimer of 18A, 37pA and 37aA, dimers of 18A coupled by Pro (18A-Pro-18A) and Ala (18A-Ala-18A), respectively. We report here the results of a thermodynamic characterization of the binding properties of these peptides to small unilamellar vesicles of POPC. Partition coefficients, Kp, were determined by fluorescence spectroscopy and binding enthalpies, deltaH, by titration calorimetry. These parameters were used to obtain the free energies, deltaG0, and entropies, deltaS0, of binding. The results of this study indicate Kp values on the order of 10(5), with interactions being enthalpically but not entropically favored in all cases. The presence of positively charged residues at the interface (18A and Ac-18A-NH2) enhances binding but has little effect on the extent of bilayer penetration. The presence of tandem repeats decreases lipid affinities for these small, highly curved bilayers. Our results are consistent with the idea that interaction appears to be confined largely to the surface, with some degree of penetration of the hydrophobic face of the helix into the interior of the bilayer.     

Formation of novel thermoplastic composites using bicomponent nonwovens as a precursor

This study focuses on a novel technique to produce thermoplastic composites directly from bicomponent nonwovens without using any resins or binders. Conceptually, the structure of the bicomponent fibers making up these nonwovens already mimics the fiber–matrix structure of fiber reinforced composites. Using this approach, we successfully produced isotropic thermoplastic composites with polymer combinations of polyethylene terephthalate/polyethylene (PET/PE), polyamide-6/polyethylene (PA6/PE), polyamide-6/polypropylene (PA6/PP), and PP/PE. The effects of processing temperature, fiber volume fraction, and thickness of the preform on the formation and structure of the nonwoven composites were discussed. Processing temperatures of 130 and 165 °C for PE and PP matrices, respectively, resulted in intact composite structures with fewer defects, for fiber volume fraction values of up to 51%. Moreover, an insight into the changes on the fine structure of the bicomponent fibers after processing was provided to better explain the mechanics behind the process. It is hypothesized that the composite fabrication process can result in annealing and increases the degree of crystallinity and melting temperature of polymers by thickening lamellae and/or removing imperfections. One of the other outcomes of this study is to establish what combination of mechanical properties (tensile and impact) nonwoven composites can offer. Our results showed that compared to glass mat reinforced thermoplastic composites, these novel isotropic nonwoven composites offer high specific strength (97 MPa/g cm⁻³ for PA6/PE), very high strain to failure (152% for PP/PE), and superior impact strength (147 kJ/m² for PA6/PP) which can be desirable in many critical applications.