Unique but diverse: some observations on the formation, structure, and morphology of halloysite

New insights from the recent literature are summarised and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is positively charged at pH ~2. The opposing sheet charge would facilitate interlayer uptake of H₂O molecules. When halloysite intercalates certain polar organic molecules, additional (hkl) reflections appear in the X-ray diffractogram, suggesting layer re-arrangement which, however, is dissimilar to that in kaolinite. Associated oxides and oxyhydroxides of Fe and Mn may limit the growth of halloysite particles as does incorporation of Fe into the structure. Particles of different shape and iron content may occur within a given sample of halloysite

Resources Confirmation for Tourism Destinations Marketing Efforts Using PLS-MGA: The Moderating Impact of Semirural and Rural Tourism Destination

This study presents a framework to empirically validate the relationship between the tangible and intangible measures on tourism destination marketing efforts. Uniquely, a case study was developed involving two different nature of tourism destinations (semirural and rural) and is incorporated into the framework to assess its moderating effect on the relationships among the predictors and destination marketing efforts. Two hundred and ninety-three usable responses were collected using a questionnaire survey. Partial least squares structural equation modelling was utilized to perform latent variable and multi-group analyses (MGA). The findings revealed that destination appeal was found to be the biggest concern among tourists visiting semirural and rural tourism destinations in Sarawak. For intangible components, both service quality and destination image were found to be significantly related to destination marketing efforts at a semirural tourism destination. Interestingly, for MGA results, it was worthwhile to learn that the relationship between service quality and destination marketing efforts happened to have a stronger impact on semirural than rural tourism destination. Hence, the proposed framework and research findings from this case study have provided significant insights that help various tourism stakeholders to better strategize and position semirural and rural tourism, particularly in the scenario of Sarawak, Malaysia. Future studies can examine this framework and test at other tourism destinations in Malaysia or in some other countries

Clean Drinking Water Data (Analysis)

This dataset relates to the analysis of the mechanical properties, the fibre structural properties and the mathematical models. <div><br></div><div>The analyses were computed using four MS Excel spreadsheets:</div><div>ANALYSIS Mech Prop ...xls: analysis of mechanical properties from each specimen</div><div>ANALYSIS Fibre Diam...xls: analysis of fibre diameter</div><div>ANALYSIS Pore Diam...xls: analysis of pore size</div><div>analysis_dib...xls: analysis of the mathematical models used in this paper to predict stiffness (E), fracture strength (sU) and water flux</div><div><div><div> </div></div></div

Electrosprayed multi-core alginate microcapsules as novel self-healing containers

Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Results showed that epoxy resin was successfully encapsulated within alginate matrix to form porous (multi-core) microcapsules with pore size ranged from 5–100 μm. The microcapsules had an average size of 320 ± 20 μm with decomposition temperature at 220 °C. The loading capacity of these capsules was estimated to be 79%. Under in situ healing test, impact specimens showed healing efficiency as high as 86% and the ability to heal up to 3 times due to the multi-core capsule structure and the high impact energy test that triggered the released of epoxy especially in the second and third healings. TDCB specimens showed one-time healing only with the highest healing efficiency of 76%. The single healing event was attributed by the constant crack propagation rate of TDCB fracture test. For the first time, a cost effective, environmentally benign and sustainable capsule-based self-healing system with multiple healing capabilities and high healing performance was developed

A Comparative Analysis of the Reinforcing Efficiency of Silsesquioxane Nanoparticles versus Apatite Nanoparticles in Chitosan Biocomposite Fibres

A comparative analysis of the effects of polyhedral oligomeric silsesquioxane (POSS) and hydroxyapatite (HA) for reinforcing chitosan (CS) is given here. Wet-spun CS nanocomposite fibres, blended with HA or POSS nanoparticles, at varying concentrations ranging from 1 to 9% (w/w) were stretched until rupture to determine the mechanical properties related to the elasticity (yield strength and strain, stiffness, resilience energy) and fracture (fracture strength strain and toughness) of the composite. Two-factor analysis of variance of the data concluded that only the fracture-related properties were sensitive to interaction effects between the particle type and concentration. When particle type is considered, the stiffness and yield strength of CS/POSS fibres are higher than CS/HA fibres—the converse holds for yield strain, extensibility and fracture toughness. With regards to sensitivity to particle concentration, stiffness and yield strength reveal trending increase to a peak value (the optimal particle concentration associated with the critical aggregation) and trending decrease thereafter, with increasing particle concentration. Although fracture strength, strain at fracture and fracture toughness are also sensitive to particle concentration, no apparent trending increase/decrease is sustained over the particle concentration range investigated here. This simple study provides further understanding into the mechanics of particle-reinforced composites—the insights derived here concerning the optimized mechanical properties of chitosan composite fibre may be further developed to permit us to tune the mechanical properties to suit the biomedical engineering application

Kappa-carrageenan/halloysite nanocomposite hydrogels as potential drug delivery systems

Novel kappa-carrageenan (Kc)/halloysite nanotube (HNT) nanocomposite hydrogels were synthesized via physical crosslinking for the gastro-intestinal tract (GIT) release. The influence of HNT nanoparticle content on Kc/HNT hydrogel properties such as thermal, swelling, drug loading and in vitro release was examined. Thermal results revealed that the incorporation of HNT nanoparticles enhanced the thermal stability of the nanocomposite hydrogels. Also, the nanocomposite hydrogels showed higher swelling, drug loading and release behavior compared to the pure Kc hydrogel. In vitro release from the Kc-HNT hydrogels exhibited that rhodamine B (RB), a cationic model drug, released higher than orange G (OG), an anionic model drug. RB in vitro release from the nanocomposite hydrogels reached to approximately 72%, while 54% of OG was released. Finally, in vitro cytotoxicity test revealed that both Kc and Kc-HNT hydrogels are biocompatible. Taking together, it was shown that Kc-HNT hydrogels may have a great potential applications in oral drug delivery systems

Electrospun Nanofibrous Membranes of Polyacrylonitrile/Halloysite with Superior Water Filtration Ability

The necessity of benefiting a breakthrough in filtration technology has led to increasing attention in advanced functional nanosized materials such as nanofibers for filtering devices as a solution for providing water at lower energy costs. In this study, electrospun polyacrylonitrile (PAN) nanofibrous membranes were reinforced by 1, 2, and 3% w/w of halloysite nanotubes (HNTs) in order to improve their mechanical properties, thermal stability and water filtration performance for the possible application as water filtration membranes. Morphological analysis revealed the highly porous and nanofibrous structure of membranes which further confirmed by surface area analysis (BET). Incorporation of HNTs enhanced the mechanical properties of the membranes such as tensile strength and elongation at break (especially at 1% w/w HNTs) while resulted in significant improvement of their thermal properties. Moreover, PAN/HNTs membranes showed excellent oil/water separation performance, while incorporation of HNTs led to increase in water flux rate, which is considered as a key point in water filtration membranes. Additionally, heavy metal ion adsorption performance of the membranes showed a significant increase by incorporation of 3% w/w HNTs. These results signified the potential of electrospun PAN/HNTs nanofibrous membranes to be used for water filtration applications