Joanne Yip

Graphene nucleation on transition metal surface: structure transformation and role of the metal step edge.

The nucleation of graphene on a transition metal surface, either on a terrace or near a step edge, is systematically explored using density functional theory calculations and applying the two-dimensional (2D) crystal nucleation theory. Careful optimization of the supported carbon clusters, C(N) (with size N ranging from 1 to 24), on the Ni(111) surface indicates a ground state structure transformation from a one-dimensional C chain to a 2D sp(2) C network at N ≈ 10-12. Furthermore, the crucial parameters controlling graphene growth on the metal surface, nucleation barrier, nucleus size, and nucleation rate on a terrace or near a step edge are calculated. In agreement with numerous experimental observations, our analysis shows that graphene nucleation near a metal step edge is superior to that on a terrace. On the basis of our analysis, we propose the use of graphene seeds to synthesize high-quality graphene in large area.

Low temperature plasma-treated nylon fabrics

Abstract Nylon 6 fabrics were treated with low temperature plasma (LTP) with three non-polymerizing gases: (i) oxygen, (ii) argon and (iii) tetrafluoromethane. After plasma treatment, the properties of the fabric, including surface morphology, low-stress mechanical properties, air permeability and thermal properties, were investigated. The nylon fabrics treated with different plasma gases exhibited different morphological changes. Low-stress mechanical properties obtained by means of the Kawabata evaluation system fabric (KES-F) revealed that the surface friction, tensile, shearing, bending and compression properties altered after the treatments. The changes in these properties are believed to be related closely to the inter-fiber/inter-yarn frictional force induced by the LTP treatment. A slightly decrease in the air permeability of the treated fabrics was found which is probably due to plasma action effecting on increase in the fabric thickness and a change in the fabric surface morphology. The change in the thermal properties of the treated fabrics was in good agreement with the above findings and can be attributed to the amount of air trapped between the yarns. This experimental work suggests that the changed properties induced by LTP can effect an improvement in certain textile products.

Comparative study of liquefaction process and liquefied products from bamboo using different organic solvents.

The effects of various solvents, including phenol, ethylene glycol (EG) and ethylene carbonate (EC), and different liquid ratios on the liquefaction of bamboo, have been studied systematically in this paper. The processes were catalyzed by hydrochloride acid at 180 degrees C in autoclaves for different reaction times. The results show that phenol is the optimum solvent for bamboo liquefaction with a yield up to 99%. The Fourier transform-infrared (FT-IR) analyses of the residues show that cellulose, hemicelluloses and lignin are almost decomposed when using phenol as solvent. The gel permeation chromatography (GPC) results of the liquid products show that the high molecular weight of bamboo decreases significantly to around 1800 g mol(-1) after liquefaction. The gas chromatography and mass spectrometry (GC-MS) analysis shows that low boiling point products of liquefied bamboo are similar regardless of the type of solvent used.

How does visual merchandising affect consumer affective response

Purpose – The aim of this article is to investigate the relationship between visual merchandising elements and consumer affective response by focusing on a function‐oriented product – intimate apparel.Design/methodology/approach – In this paper, a different perspective on visual merchandising is offered through the different types of intimate apparel retailers (from fashion‐oriented, mass market‐oriented to fashion forward). This is presented in an interpretive study of Hong Kong Chinese female consumers, between the ages of 25 and 35. A qualitative approach is employed and the grounded theory method is chosen. A total of eight focus group interviews are conducted with 64 subjects.Findings – The findings indicate that participating subjects have two points of view when evaluating visual store displays, which include utilitarian and hedonic aspects. The utilitarian aspect relates to the actual needs of consumers, such as garment deterioration, seasonal changes and occasions. The hedonic aspect finds that t...

Application of the Box-Behnken design to the optimization of process parameters in foam cup molding

Currently, foam molding technologies are widely adopted for most bra styles, which demonstrate the incomparable advantages in the contemporary intimate apparel industry. The determination of proper molding conditions, such as molding temperatures and length of time on the basis of cup sizes and styles, is crucial in achieving the required cup shape with high stability, which is regarded as the most challenging part of the molded bra making process. To determine the optimal process parameter settings, numerous process trials are generally required to evaluate the molding variables and their interactions. This study proposes a novel systematic methodology to identify the optimal molding process parameters based on design of experiment (DOE) and a parameterization-based remesh method to evaluate the 3D shape conformity of molded cups. By solving the regression equation obtained from a Box-Behnken design (BBD) and analyzing the response surface plots, the results prove that molding temperature has greater influence than the length of the dwell time on the 3D shape conformity of molded cups. The optimal molding conditions can be determined for the cup depths of different sized mold heads, which are validated by the experimental results.

Chitosan microcapsules loaded with either miconazole nitrate or clotrimazole, prepared via emulsion technique.

In this paper, a simple and versatile coacervation technique has been developed by using an ultrasound-assisted oil/water emulsion method for the preparation of antifungal agent-loaded microcapsules. Two types of chitosan microcapsules are successfully prepared. The mean particle size of the chitosan/miconazole nitrate microcapsules is 2.6 μm and that of the chitosan/clotrimazole microcapsules is 4.1 μm. The encapsulation efficiency of the chitosan/miconazole nitrate microcapsules (77.58-96.81%) is relatively higher than that of the chitosan/clotrimazole microcapsules (56.66-93.82%). The in vitro drug release performance of the microcapsules shows that the chitosan/miconazole nitrate microcapsules release about 49.5% of the drug while chitosan/clotrimazole microcapsules release more than 66.1% of the drug after 12h under a pressure of 5 kg at pH 5.5, which is similar to the pH of human skin. The prepared drug-loaded microcapsules could be applied onto bandages or socks, and will continuously release antifungal drugs in a controlled manner under pressure.

Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

Abstract Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

2D and 3D anatomical analyses of hand dimensions for custom-made gloves.

Measuring hand anthropometric data for the development of good-fitting gloves is crucial. In pursuing higher accuracy in hand anthropometric measurements, scanning of hand surfaces with the aids of image analysis system to acquire measurements is an alternative to the manual methods. This study proposes a new hand measuring approach by using 2D and 3D scanning which are evaluated through comparisons of manual measurements. Thirty-three dimensions are measured by using (1) tape and calliper measurement; (2) 2D image analysis; (3) 3D image analysis based on ten captures; and (4) 3D image analysis based on three captures, respectively. Repeated-measures ANOVA, correlation analysis and RMSE are used to examine the results. The hand dimensions obtained from the four methods are highly linearly correlated. Hand data taken from 3D image analysis has no significant difference compared with manual measurements on hand and wrist circumferences, length and breadth dimension, regardless of the number of captures.

Study of plasma-etched and laser-irradiated polyamide materials

Abstract.Surface morphological structures of the Low Temperature Plasma (LTP) and UV Excimer Laser treated polyamide materials were investigated. The effects of different parameters were studied by using Scanning Electron Microscope (SEM). For LTP treatment, different non-polymerizing gases (oxygen, argon), discharge power and exposure time were selected as treatment parameters. For Laser treatment, high-fluence (above ablation threshold), low-fluence (below ablation threshold) and number of pulses were studied. High-fluence laser treatment gives the most distinct ripple-like structures on the surface of polyamide and these structures are more obvious when the number of pulses increases. Low-fluence treated polyamide develops some stripes of sub-micron size within a narrow fluence window. On the other hand, oxygen and argon plasma also gives ripple-like structures but with smaller dimensions than those due to high-fluence laser treatment. Although the morphological modification features on the polyamide fiber surface developed under laser and LTP treatments are not identical, they have certain similarity.

Development of phyllanthin containing microcapsules and their improved biological activity towards skin cells and Staphylococcus aureus

Chitosan based microcapsule which encapsulated with phyllanthin was developed by simple coacervation. The composition and surface morphology of phyllanthin containing microcapsules were analyzed by Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy, respectively. The release of phyllanthin from the microcapsules was found to be more than 60% after 120 h. In vitro biological assays demonstrated that these phyllanthin containing microcapsules showed a stronger anti-oxidation potential on both human fibroblasts and keratinocytes as well as a better growth inhibitory activity towards Staphylococcus aureus.