18 research outputs found
Chapter 34 - Biocompatibility of nanocellulose: Emerging biomedical applications
Nanocellulose already proved to be a highly relevant material for biomedical
applications, ensued by its outstanding mechanical properties and, more importantly, its biocompatibility. Nevertheless, despite their previous intensive
research, a notable number of emerging applications are still being developed.
Interestingly, this drive is not solely based on the nanocellulose features, but also
heavily dependent on sustainability. The three core nanocelluloses encompass
cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BNC). All these different types of nanocellulose display highly interesting biomedical properties per se, after modification and when used in
composite formulations. Novel applications that use nanocellulose includewell-known areas, namely, wound dressings, implants, indwelling medical
devices, scaffolds, and novel printed scaffolds. Their cytotoxicity and biocompatibility using recent methodologies are thoroughly analyzed to reinforce their
near future applicability. By analyzing the pristine core nanocellulose, none
display cytotoxicity. However, CNF has the highest potential to fail long-term
biocompatibility since it tends to trigger inflammation. On the other hand, neverdried BNC displays a remarkable biocompatibility. Despite this, all nanocelluloses clearly represent a flag bearer of future superior biomaterials, being
elite materials in the urgent replacement of our petrochemical dependence
APPLICATIONS OF INNOVATIVE BUILDING MATERIAL AND COMPUTER VISION METHODS IN GEOTECHNICAL ENGINEERING
Ph.D
Innovative Materials and Methods for the Removal of Pollutants from the Environment
The progress of society has led to an improvement of the quality of life of a significant number of people. On the other hand, anthropogenic pollution dramatically increased, with serious consequences for the environment and human health. Controlling and remedying environmental pollution is one of the main challenges of our century. Fundamental and applicative research are called to collaborate, involving scientists in the development of realistic and effective systems for the prevention and the removal of pollutants from the environment. Spreading knowledge is among the missions of researchers and this is the aim of this book, offering an updated view on innovative materials and methods for pollutant treatment. It is composed of 18 articles, among them 5 reviews and 13 original articles, dedicated to new adsorbent materials (inorganic, organic, and hybrid materials) for the capture of pollutant species and for their catalytic conversion into non-toxic substances, and to bioremediation approaches to treat contaminated media. Water, air, and soil pollution was investigated, both at the lab and large scale, with special relevance for wastewater treatments for the removal of heavy metals and organic pollutants. We are grateful to “Molecules” for the opportunity to edit the Special Issue on “Innovative Materials and Methods for the Removal of Pollutants from the Environment”. We created, for this book, an original cover image, dedicated to the efforts of chemistry to defend the beauty of environment, represented by flowers, against every prejudice that considers chemistry an enemy of life
A new mixed model based on the enhanced-Refined Zigzag Theory for the analysis of thick multilayered composite plates
The Refined Zigzag Theory (RZT) has been widely used in the numerical analysis of multilayered
and sandwich plates in the last decay. It has been demonstrated its high accuracy in predicting global quantities, such as maximum displacement, frequencies and buckling loads, and local quantities such
as through-the-thickness distribution of displacements and in-plane stresses [1,2]. Moreover, the C0
continuity conditions make this theory appealing to finite element formulations [3]. The standard RZT,
due to the derivation of the zigzag functions, cannot be used to investigate the structural behaviour
of angle-ply laminated plates. This drawback has been recently solved by introducing a new set of
generalized zigzag functions that allow the coupling effect between the local contribution of the zigzag
displacements [4]. The newly developed theory has been named enhanced Refined Zigzag Theory (en-
RZT) and has been demonstrated to be very accurate in the prediction of displacements, frequencies,
buckling loads and stresses. The predictive capabilities of standard RZT for transverse shear stress
distributions can be improved using the Reissner’s Mixed Variational Theorem (RMVT). In the mixed
RZT, named RZT(m) [5], the assumed transverse shear stresses are derived from the integration of local
three-dimensional equilibrium equations. Following the variational statement described by Auricchio
and Sacco [6], the purpose of this work is to implement a mixed variational formulation for the en-RZT,
in order to improve the accuracy of the predicted transverse stress distributions. The assumed kinematic
field is cubic for the in-plane displacements and parabolic for the transverse one. Using an appropriate
procedure enforcing the transverse shear stresses null on both the top and bottom surface, a new set
of enhanced piecewise cubic zigzag functions are obtained. The transverse normal stress is assumed as
a smeared cubic function along the laminate thickness. The assumed transverse shear stresses profile
is derived from the integration of local three-dimensional equilibrium equations. The variational functional
is the sum of three contributions: (1) one related to the membrane-bending deformation with a
full displacement formulation, (2) the Hellinger-Reissner functional for the transverse normal and shear
terms and (3) a penalty functional adopted to enforce the compatibility between the strains coming
from the displacement field and new “strain” independent variables. The entire formulation is developed
and the governing equations are derived for cases with existing analytical solutions. Finally, to assess
the proposed model’s predictive capabilities, results are compared with an exact three-dimensional solution,
when available, or high-fidelity finite elements 3D models. References: [1] Tessler A, Di Sciuva
M, Gherlone M. Refined Zigzag Theory for Laminated Composite and Sandwich Plates. NASA/TP-
2009-215561 2009:1–53. [2] Iurlaro L, Gherlone M, Di Sciuva M, Tessler A. Assessment of the Refined
Zigzag Theory for bending, vibration, and buckling of sandwich plates: a comparative study of different
theories. Composite Structures 2013;106:777–92. https://doi.org/10.1016/j.compstruct.2013.07.019.
[3] Di Sciuva M, Gherlone M, Iurlaro L, Tessler A. A class of higher-order C0 composite and sandwich
beam elements based on the Refined Zigzag Theory. Composite Structures 2015;132:784–803.
https://doi.org/10.1016/j.compstruct.2015.06.071. [4] Sorrenti M, Di Sciuva M. An enhancement
of the warping shear functions of Refined Zigzag Theory. Journal of Applied Mechanics 2021;88:7.
https://doi.org/10.1115/1.4050908. [5] Iurlaro L, Gherlone M, Di Sciuva M, Tessler A. A Multi-scale
Refined Zigzag Theory for Multilayered Composite and Sandwich Plates with Improved Transverse Shear
Stresses, Ibiza, Spain: 2013. [6] Auricchio F, Sacco E. Refined First-Order Shear Deformation Theory
Models for Composite Laminates. J Appl Mech 2003;70:381–90. https://doi.org/10.1115/1.1572901
7th International Conference for Young Chemists (ICYC 2019)
Along with the celebration of USM Golden Jubilee in 2019, we bring you the most anticipated event
in commemorating the 50 years of USM excellence in higher education. The International Conference
for Young Chemists (ICYC) is a biennial conference organised by the postgraduate students of the
School of Chemical Sciences, Universiti Sains Malaysia with the aim to gather local and international
postgraduate researchers to create interaction and networking in the field of Chemistry. The idea of
this conference started back in the year 2001 where it was known as the Regional Conference for
Young Chemists (RCYC) targeting postgraduate researchers from the Asia Pacific Region (Malaysia,
Singapore, Indonesia, the Philippines, India and Japan). What used to be the Regional Conference for
Young Chemists (RCYC), has been rebranded into the International Conference for Young Chemists as
we know it today. We are targeting postgraduate researchers from all around the world rather than
just in this region. In fact, in August 2019, it is going to be the seventh time this international
conference is going to be hel
Synthesis and evaluation of novel porous materials for environmental remediation
Porous materials have been widely used as adsorbents for water treatment due to their unique properties such as high surface area, excellent mechanical properties and good chemical stability. The work in this thesis aimed to develop novel porous materials for pollution remediation, with the focus being on materials that can be produced economically and environmentally friendly. The first part of this thesis covers two types of mesoporous carbon materials including mesoporous and magnetic mesoporous carbon materials which were fabricated through a soft templating method (Chapter 3). It has been shown that these porous carbon materials with monolithic form have high surface area, which is envisaged excellent adsorbent capacity. But there are some drawback which limit their use for water treatment as the preparation of these materials is time consuming, there are high operation cost and difficulties in regeneration and operation. Cellulose was considered as an attractive alternative material for preparation of porous materials for pollution remediation because it is naturally abundant, renewable, non-toxic and a lowcost biopolymer.In the second part of this work a cellulose-based hydrogel was successfully synthesized using hydroxypropyl cellulose (HPC) with divinyl sulfone (DVS) as a chemical crosslinker via a modified temperature induced phase separation (TIPS) method (Chapter 4). The HPC hydrogel obtained was characterised and the results showed that the properties of this hydrogel depended on the gelation temperature. The FTIR results confirmed the chemical cross-linking between HPC and DVS. HPC hydrogel demonstrated a flexible behaviour without breakage under compression tests. In addition, there were good shape recovery properties upon adsorption of water. The morphology of the cross-linked HPC hydrogel showed an interconnected macroporous network structure, which allowed application for water purification.Further work was then carried to develop a new and simple method to prepare a novel thermoresponsive HPC hydrogel with a graded pore size (Chapter 5). This method combined two approaches, varying the temperature between the upper and lower part of the hydrogel utilising the lower critical solution temperature (LCST) via the temperature induced phase separation (TIPS) method, which achieved a gradual change in pore geometry and pore size. The added inclusion of cryogenic treatment of the sample ensured a gradient porous HPC hydrogel was obtained with high permeability. Double network (DN) hydrogels have a structure that can effectively improve the adsorption capacity as the second network can introduce more functional groups into hydrogel structures, which is of great importance in the adsorption process due to improve the adsorption capacities. The DN hydrogels can also improve the mechanical strength of hydrogel materials, which makes it easier to regenerate. To this purpose, novel hybriddouble networks hydrogel was prepared in this work via mixing two types of crosslinked polymers, these were covalently crosslinked HPC with DVS and ionically crosslinked alginate with calcium ions (Chapter 6). Alginate was selected to be the second network polymer as alginate has carboxylate functional groups that can be used to remove cationic pollutant by electrostatic interactions, thus improving the adsorption capacity of the HPC single network (HPC SN) hydrogel. SEM images of the double network produced s confirmed that the hydrogel was composed of two independently cross-linked networks with a homogeneous interconnecting porous structure. The mechanical tests on the DN hydrogel showed that it was much stronger compared with HPC SN hydrogel. The adsorption and filtration of organic pollutants by HPC hydrogel were investigated through dye adsorption experiments (Chapter 7). The results were showed a great ability of HPC hydrogel for selective adsorption towards MB dye. In order to evaluate the possibility of reuse of HPC hydrogel, the recyclability of these materials was examined. The obtained results indicated that the reusability of the HPC hydrogel was at some cycles without any loss in its sorption behaviour. Therefore, the HPC hydrogel can be a good reusable and economical adsorbent to remove the cationic species. It is important to note that HPC hydrogel column was further used for the first time for selective separation of dye mixtures by simple gravity filtration and the hydrogel can be re-used multiple times. Despite being one of the most promising types of porous materials for environmental applications, their low adsorption capacity is a significant disadvantage for their use inthese applications. Adsorption of methylene blue dye (MB) on HPC/CA DN hydrogel was investigated through batch and column adsorption experiments and compared with HPC SN hydrogel (Chapter 7). The adsorption isotherms for both HPC SN and HPC/CA DN hydrogels fitted well with the Langmuir adsorption model and the maximum adsorption capacity of HPC/CA DN hydrogel was found to be 169.49 mg g-1, which is larger than for the HPC SN hydrogel (112.35 mg g-1). The results showed a significant pH-dependent equilibrium for the adsorption capacity of MB dye for both hydrogels in this study, which decreased dramatically with decreasing the pH of the MB dye solution. This meant that the MB-loaded HPC hydrogel could be easily regenerated under acidic conditions. The thermodynamic analysis of MB dye adsorption onto both HPC SN andHPC/CA DN hydrogels were also studied and the process was shown to be an exothermic and spontaneous process. An adsorption kinetic study was also carried out and the results obtained showed that the adsorption of MB dye adsorption on both hydrogels was well described by the pseudo-second-order kinetic model. In the column study, the adsorbent reuse was investigated and the selective separation of a dye mixture was also studied through ten cycles. Both hydrogels columns showed efficient selective adsorbent for cationic dyes, with the removal of MB dye being very efficient, whilst extremely low removal of FL dye. However, the HPC/CA DN hydrogels column exhibited a higher adsorption capacity than HPC SN hydrogel due to the dual functional groups (hydroxyl and carboxyl groups) in HPC/CA DN hydrogel. Based on the selective adsorptiontowards cationic methylene blue over anionic sodium fluorescein dye, HPC SN and HPC/CA DN hydrogels columns could easily separate two dyes from aqueous solutions of dye mixtures by simple gravity filtration. Both HPC SN and HPC/CA DN hydrogel column showed high separation efficiency of more than 99%. It was also found that separation efficiency of the HPC SN decreased to 86% by the 10th cycle for this column, while no significant losses in the separation efficiency were detected even after ten cycles for the HPC/CA DN hydrogel column. These results show that the HPC/CA double network polymer hydrogels have great potential for improving the adsorption capacity with good reusability and would be a promising eco-friendly adsorbent for the treatment of dye wastewaters
SynerCrete’18: interdisciplinary approaches for cement-based materials and structural concrete: synergizing expertise and bridging scales of space and time, vol. 2
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