Advanced Materials Research Vol. 911

Abstract: The present work proposes the adsorption of methyl violet (MV) from two solution systems including single MV and binary MV-Cu²⁺ systems by activated carbon (AC) prepared from tamarind seeds in a batch system. Parameters including contact time, solution pH, adsorbent dose, and initial dye concentration were studied. The morphology of the AC was determined by scanning electron microscopy (SEM). The results showed the maximum adsorption of MV dye onto the AC at a contact time of 60 min, solution pH of 9.0 and adsorbent dose of 0.2 and 0.5 g for the single and binary solution systems, respectively. The presence of copper ions in binary solution system decreased the adsorption efficiency of MV dye onto the AC. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherms.

Abstract: Due to a shortage of wood source fibre in paper making industrys interest to agriculture residues fibre as a potential fibre sources in this industry. In this situation, importance has been developing in the paper industry from agriculture residue that will replace the wood fibre. Cocoa pod husk and Corn stalk are agriculture residues, which is good materials for paper production. The objectives of this study are to investigate the chemical characterization and surface morphology structure of these materials. The main components of materials which are cellulose, hemicellulose, lignin and ash content were parameters that involved in determination of chemical characterization in this study. The determination of chemical composition was accordance to Kurshner-Hoffner approach (cellulose), Chlorine Method (hemicellulose), T 222 om-06 (lignin) and T 211 om-07 (ash content). Scanning electron microscopy was used to observe the surface structure of materials. From results obtained, corn stalk shows the higher amount in cellulose (39%) and hemicellulose (42%) content compared to the cocoa pod husk. In addition, lower lignin content also obtained in Corn stalk (7.3%) rather than that Cocoa pod husk (14.7%). From Scanning electron microscopy images, Corn stalk and Cocoa pod husk contained abundance lignocellulosic and rough surface structure due to the untreated materials. The result either chemical characterization or surface morphology that obtained in Corn stalk and Cocoa pod husk fibre wastes can be used successfully as an alternative fibres sources in papermaking application.

Abstract: In the paper the results of control drug release from different forms of carriers are presented. Dibutyrylchitin, chitosan, polylactid acid and polycaprolactone have been used as matrices for delivery of therapeutic substances (ibuprofen and salicylic acid). Two configurations of matrices for drug delivery have been found. Flat drug delivery systems (films) and spherical matrices (beads) were tested in the aim of control drug transport. To control the drug release, matrices have been modified. The release of active substances from films has been tested in buffer solution of pH 5.5. Spherical matrices have been tested in buffer solutions of pH 1.4 and pH 7.2. To experimental data First order and two stage models were fitted.

Abstract: Angiogenesis is the formation of new microvascular network from the pre-existing blood vessel. In tissue engineering approaches, angiogenesis is essential for the promotion of micro-vascular network inside an engineered scaffold construct, mimicking a functional blood vessel in vivo. In the in vivo system, the formation of new blood vessels depends on the properties fibrin gel extracellular matrix. In this study, we have investigated the effect of different fibrinogen and thrombin composition on the biophysical properties of fibrin gel. Higher concentration of thrombin (4.0 Units/milliliter) yields a shorter clotting time of the fibrin gel and result in better water uptake property while at lower concentration of thrombin (0.5 Units/milliliter), the clotting time takes much longer. Also, at lowest concentration ratio of fibrinogen to thrombin (0.5 milligram/milliliter to 4.0 Units/milliliter), the turbidity study shows the lowest absorbance compared to other samples. Different concentration of fibrinogen and thrombin also affect the microstructure of the fibrin gel. The variation of these properties will be then manipulated to be used for in vitro angiogenesis. This study opens broader application of fibrin extracellular matrix in regenerative medicine and tissue engineering researches.

Abstract: Conventional techniques for detection of bacteria/cell and assessment of cancer cell typically use DNA techniques, Western blot and ELISA kits that are high cost, complicated processes and long time consuming. Our researches focus on rapid, portable, simple and highly sensitive separation and detection of cells/bacteria/biomolecules for field-use diagnosis. An ideal portable biosensor (molecular or whole cells detections) unit must have several important features: rapid detection time (<10 minutes), high sensitivity (pM level for molecular detection, 10³ cells/ml for whole cell detection), high specificity, small and inexpensive instrumentation configuration. Electrochemical impedance/conductance sensing is preferred over optical detection because of cost and portability concerns. Cancer cell detection using heterogeneous medical samples require continuous isolation, sorting, and trapping of the target bioparticles and immunocolloids within a diagnostic chip. We have developed several electrokinetic strategies to rapid separation, concentration and detection of cells/bacteria/biomolecules in a microfluidic chip using such as dielectrophoresis (DEP), traveling-wave dielectrophoresis (twDEP) and electrohydrodynamics (EHD). Several key techniques we done, which on a rapid/simple/label-free detection platform for the highly sensitive on-chip separation/identification/quantification will be introduced in this paper.

Abstract: Flexible polyurethane (PU) foams were prepared by replacing commercial petroleum-based polyether polyol with palm oil-based polyol up to 50 wt%. Palm oil was converted to polyol by transesterification reaction with glycerol using calcium oxide as a catalyst. PU foams were then prepared from reaction between mixtures of palm oil-based polyol and petrochemical polyols with toluene diisocyanate (TDI) using water as blowing agent. The morphology and physical-mechanical properties including apparent density, indentation hardness, compressive deflection coefficient or support factor, tensile strength, and tear strength of the prepared foams were characterized and compared to those of reference foam prepared using only conventional petrochemical polyols. Scanning electron microscopy (SEM) indicated that the cellular structures of all the prepared foams were semi-open and the cell size decreased with higher amount of palm oil-based polyol. The apparent densities and the compressive deflection coefficient of the PU foams increased with the increasing amount of palm oil-based polyol, while the indentation hardness showed the opposite tendency. Furthermore, the obtained foam modified with palm oil-based polyol of 20 wt% were found to have the highest tensile and tear strengths.

Abstract: Tight binding Hamiltonian model has been used in studying the influence of the surrounding medium on electrical conductivity of a Poly (dG)-Poly (dC) DNA molecule. This effect is studied in room temperature by taking into account twisting motion with two different low frequencies separately. Transfer matrix technique and scattering matrix method have been employed simultaneously. The current voltage characteristics and the differential conductance show that as the backbone disorder increases, the current decreases and the threshold voltage rises. However as the backbone disorder continues to increase, the reverse of the above phenomenon is observed.

Abstract: Nowadays the usage of polymer on articular replacement (arthropasty) is common because of their known usage in orthopedic surgery and biocompatibility. The polymeric material such as polyethylene and polyacetal are common materials used in surgical repair of joint due to the arthritic or dysfunctional joint surface. The surgical repair is done by replacing the damage part with something better or remodeling or realigning the joint by osteotomy procedures. In this case, for both hip and knee replacement, chrome-cobalt and polymer are commonly used. According to Jennifer Brown, the cost for knee replacement is approximate to USD$15,000 per procedure with the estimation of total knee replacement is 600,000 annually in United States. Currently, the aggregate of annual cost for total knee replacement is about USD$9 billion. The usage of chrome-cobalt and polymer is very common and save but the cost is very expensive. The other disadvantage is it usually last only for 10 years for hip and knee replacement.

Abstract: This study investigated the flow behavior of feedstock containing hydroxyapatite (HAp) powder with palm stearin (PS) based binder system. The HAp was synthesized via chemical precipitation method with the use of waste of clamshells. The result showed that single phase synthesized HAp was successfully formed at annealing temperature and pH solution of 850°C and 6.5, respectively. The synthesized HAp with a volume fraction of 65% was then mixed with PS and and Polyethylene binder at 160°C to prepare a feedstock. From the rheological test result, it was found that the feedstock exhibited a pseudoplastic behavior with low values of shear sensitivity in comparison with commercial HAp.

Abstract: Due to the growing energy demands of the world and the rapid depletion of fossil fuels, it is necessary to study new energy sources. The waste have a great potential to be tapped, as besides being a raw material abundant, their use helps in reducing the level of environmental pollution and curbing the volume of waste in cities. However, one should know well the combustion process these waste before using them as fuel. Thus, Ignition behavior of combustible wastes was studied in a built fixed bed reactor. To provide a controlled thermal radiation for the ignition instant, a radiative heat flux is generated by a metal surface called a cone heater calibrated to establish the radiative heat flux density provided by a thermal resistance of 2 kW. The heat flux was 25 to 30 kWm² over the top surface of the fuels. To validate the process, experiments with charcoal were performed varying the diameter of particles and air flow. After this, the polyethylene and human feces were analyzed. Their effects were investigated on the ignition time.