To improve textural attributes of puffed corn-fish snack, the effects of 1%, 1.5%, and 2% of calcium carbonate, magnesium silicate (talc), sodium bicarbonate as well as 5% and 10% of wheat bran (as the nucleating materials) on textural attributes were studied. Sensory evaluation, bulk density, expansion ratio, maximum force, and count peaks were measured using the Kramer test. The results showed that all of the additives except bran significantly enhanced the texture. Among them, talc at 0.5% was the best to enhance the density and expansion ratio. Effects of using 0.5% talc on puffed corn-fish snack microstructure were studied using scanning electron microscopy. The average cell diameter of 109 ± 48 μm and cell numbers per square centimeter of 67.4 for talc-treated products were obtained, while for nontalc-treated extrudates, average cell diameter of 798 ± 361 μm and cell numbers per square centimeter of 13.9 were found. Incorporation of 0.5% w/w of magnesium silicate reduced (7-fold) the average cell diameter while increased (4-fold) the cell number.
Calcium silicate (CaSiO3, CS) ceramics are promising bioactive materials for bone tissue engineering, particularly for bone repair. However, the low toughness of CS limits its application in load-bearing conditions. Recent findings indicating the promising biocompatibility of graphene imply that graphene can be used as an additive to improve the mechanical properties of composites. Here, we report a simple method for the synthesis of calcium silicate/reduced graphene oxide (CS/rGO) composites using a hydrothermal approach followed by hot isostatic pressing (HIP). Adding rGO to pure CS increased the hardness of the material by ∼40%, the elastic modulus by ∼52%, and the fracture toughness by ∼123%. Different toughening mechanisms were observed including crack bridging, crack branching, crack deflection, and rGO pull-out, thus increasing the resistance to crack propagation and leading to a considerable improvement in the fracture toughness of the composites. The formation of bone-like apatite on a range of CS/rGO composites with rGO weight percentages ranging from 0 to 1.5 has been investigated in simulated body fluid (SBF). The presence of a bone-like apatite layer on the composite surface after soaking in SBF was demonstrated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The biocompatibility of the CS/rGO composites was characterized using methyl thiazole tetrazolium (MTT) assays in vitro. The cell adhesion results showed that human osteoblast cells (hFOB) can adhere to and develop on the CS/rGO composites. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of cells on the CS/rGO composites were improved compared with the pure CS ceramics. These results suggest that calcium silicate/reduced graphene oxide composites are promising materials for biomedical applications.
The [Co(Me(2)Salen)(PBu(3))(OH(2))]BF4 and [Co(Me(2)Salen)(PPh(3))(Solv)]BF(4), complexes were synthesized and characterized by FT-IR, UV-Vis, (1)H NMR spectroscopy and elemental analysis techniques. The coordination geometry of [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) was determined by X-ray crystallography. It has been found that the complex is containing [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) and [Co(Me(2)Salen)(PPh(3))(EtOH)]BF(4) hexacoordinate species in the solid state. Cobalt atom exhibits a distorted octahedral geometry and the Me(2)Salen ligand has the N2O2 coordinated environment in the equatorial plane. The [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) complex shows a dimeric structure via hydrogen bonding between the phenolate oxygen and hydrogens of coordinated H2O molecule. These complexes were incorporated into Montmorillonite-K10 nanoclay. The modified clays were identified by FT-IR, XRD, EDX, TGA/DTA, SEM and TEM techniques. According to the XRD results of the new nanohybrid materials, the Schiff base complexes are intercalated in the interlayer spaces of the clay. SEM and TEM micrographs show that the resulting hybrid nanomaterials have layer structures. Also, TGA/DTG results show that the intercalation reaction was taken place successfully.
The present study investigates the development of methyl cellulose (MC)-sodium alginate (SA)-montmorillonite (MMT) clay based bionanocomposite films with interesting wound healing properties. The differential scanning calorimetry analysis of the composite films revealed presence of single glass transition temperature (Tg) confirming the miscible nature of the ternary blended films. The increase in MMT ratio in the composite films reduced the mobility of biopolymer chains (MC/SA) which increased the Tg of the film. Thermogravimetric analysis showed that dispersion of clay (MMT) at nano level significantly delayed the weight loss that correlated with higher thermal stability of the composite films. It was observed that the developed films were able to exhibit antimicrobial activity against four typical pathogenic bacteria found in the presence of wound. The developed films were able to significantly inhibit (10 mg/ml) the growth of Enterococcus faecium and Pseudomonas aeruginosa. In vitro scratch assay indicated potential wound closure activities of MC-2-4 bionanocomposite films at their respective highest subtoxic doses. In conclusion, these ternary bionanocomposite films were found to be promising systems for wound healing applications.
This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements.
Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.
Calcium silicate (CaSiO3, CS) ceramic composites reinforced with graphene nanoplatelets (GNP) were prepared using hot isostatic pressing (HIP) at 1150°C. Quantitative microstructural analysis suggests that GNP play a role in grain size and is responsible for the improved densification. Raman spectroscopy and scanning electron microscopy showed that GNP survived the harsh processing conditions of the selected HIP processing parameters. The uniform distribution of 1 wt.% GNP in the CS matrix, high densification and fine CS grain size help to improve the fracture toughness by ∼130%, hardness by ∼30% and brittleness index by ∼40% as compared to the CS matrix without GNP. The toughening mechanisms, such as crack bridging, pull-out, branching and deflection induced by GNP are observed and discussed. The GNP/CS composites exhibit good apatite-forming ability in the simulated body fluid (SBF). Our results indicate that the addition of GNP decreased pH value in SBF. Effect of addition of GNP on early adhesion and proliferation of human osteoblast cells (hFOB) was measured in vitro. The GNP/CS composites showed good biocompatibility and promoted cell viability and cell proliferation. The results indicated that the cell viability and proliferation are affected by time and concentration of GNP in the CS matrix.
The Critical State Soil Mechanic (CSSM) is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803-0.998, 0.144-0.248, and 1.727-2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated.
Formation of carbonate minerals by CO2 sequestration is a potential means to reduce atmospheric CO2 emissions. Vast amount of alkaline and alkali earth metals exist in silicate minerals that may be carbonated. Laboratory experiments carried out to study the dissolution rate in Pahang Sandstone, Malaysia, by CO2 injection at different flow rate in surficial condition. X-ray Powder Diffraction (XRD), Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDX), Atomic Absorption Spectroscopy (AAS) and weight losses measurement were performed to analyze the solid and liquid phase before and after the reaction process. The weight changes and mineral dissolution caused by CO2 injection for two hours CO2 bubbling and one week' aging were 0.28% and 18.74%, respectively. The average variation of concentrations of alkaline earth metals in solution varied from 22.62% for Ca(2+) to 17.42% for Mg(2+), with in between 16.18% observed for the alkali earth metal, potassium. Analysis of variance (ANOVA) test is performed to determine significant differences of the element concentration, including Ca, Mg, and K, before and after the reaction experiment. Such changes show that the deposition of alkali and alkaline earth metals and the dissolution of required elements in sandstone samples are enhanced by CO2 injection.
The long term objective of this research is to look into the possibility of replacing soil strength parameters such as cohesion and angle of friction with electrical resistivity value for the purpose of computing among others, factor of safety in slopes or bearing capacity of soil. This paper however is limited to the investigation of correlation between electrical resistivity with some selected soil parameters. Electrical resistivity tests, using a basic multi meter, steel moulds and other related equipment, were conducted in the laboratory on soil samples with variations in soil type, compaction energy and moisture content. The samples consisted of predominantly clay, silt and sandy size particles and were compacted in a 100 x 100 mm square mould, while the corresponding electrical resistivity tests were carried out using the disc electrode method in accordance to BS 1377. The values of the electrical parameters such as voltage, current and resistance, with the corresponding value of soil parameters such as cohesion, angle of friction and moisture content, were measured and recorded. The results of the tests produced some initial crude relationships between electrical resistivity and the selected soil parameters. The strongest correlation between electrical resistivity and angle of internal friction, φ, was obtained from the clay size samples with R2 of 0.824, while the maximum correlation between electrical resistivity and moisture content again was obtained through the clay samples with R2 of 0.818. From the other results and graphs analyzed, some consistencies and specific trends of behaviour observed gave some early indications that a more detail and precise correlation between electrical resistivity and soil strength parameters could be very well possible in future.
A study on the distribution of Recent Ostracoda in offshore sediment was carried out around the South China Sea. A total of 30 sediment samples were taken from the sampling stations between latitude 1°48’ and 7°25’N and longitude 102°09’ and 105°16’E. From this study, 79 species of ostracods belonging to 16 families and 44 genera were identified. The dominant species was Foveoleberis cypraeoides with 937 individuals obtained. There were 13 to 43 species in total. Diversity Index, H(s), was in the range of 2.1 to 3.3, whereas the dominance values were between 4.4 and 14.7%. Several environmental parameters were measured including depth, temperature and salinity. The range values for each of these parameters are 13-72 m, 25.24-30.06o C and 27.74-34.91 ppt, respectively. The sediment texture in this study area can be categorized as sand, sandy mud, clayey mud, silty mud, silty clay, clayey sand, clayey silt and silty sand. The observations revealed that abundance and diversity of ostracod appeared to be principally controlled by depth. Two faunal assemblages were identified in terms of faunal composition, namely, shallow water (Hemikrithe orientalis, Neomonoceratina iniqua, Stigmatocythere indica, Cytherelloidea leroyi and Neocytheretta snellii) and deep water (Paracypris sp., Alataconcha pterogona, Bythocytheropteron alatum, Keijella paucipunctata and Actinocythereis scutigera). A comparative analysis showed a high degree resemblance between the study area and south-eastern Malay Peninsula (the South China Sea).
Detailed geophysical investigations have been carried out using integrated geophysical methods with a view to characterising the subsurface lithologic features that might indicate suitable places for structural developments. An overview of the subsurface resistivity distribution has been achieved employing 8Vertical Electrical Soundings with the Schlumberger array and 4 2D resistivity imaging using Wenner array. In order to constrain the results of the electrical resistivity methods, we carried out a ground magnetic survey along E-W direction using the Proton precession magnetometer at 1m sampling interval. Analysis of well logs data available and VES results showed 4 to 5 geoelectric layers corresponding to sand, clayey sand, clay, silty sand and sandy clay. The 2D resistivity imaging sections showed relative decrease of apparent resistivity with depth implying a geological transition from sand with high resistivity value of about 508Ωm to clay with low resistivity value 16Ωm at depths of 0-20m and 25-50m respectively. The magnetic profiles showed that the study area was characterised by short wavelengths and amplitudes ranging from –3800 to 700 nT. The highs and lows of the magnetic responses occasioned by lithological variations and structural features were magnetically resolved. In view of the identified subsurface structures, the suggested depth to the competent layer is about 20m for low to medium structures while above 50m would be suitable for heavy or massive engineering structures. The use of integrated geophysical methods for the delineation, identification and imaging of the subsurface geological structures which could provide clues to the nature and type of foundation suitable for the development of the study area has been successfully achieved.
Three forest types were recognized at Chini watershed namely inland, seasonal flood and riverine forests. The soil physico-chemical characteristics from the three forest types were investigated to determine the soil properties variation within a landscape scale. Thirty sampling stations were established, represented by fourteen inland, nine stations in seasonal flood forest and seven in riverine forest. In each station, three soil samples were taken at 0-15 cm depth by using an auger. The study showed 71% of the soil in the inland forest was found to be dominated by clay, 44% of the soil in the seasonal flood forest by clay loam and 42% of the soil in the riverine forest was dominated by silty clay. The pH of all three types of forest studied was acidic and insignificantly different. Organic matter content in the study sites was moderate. The mean of electric conductivity (EC) and cation exchange capacity (CEC) values in the studied soils were low. Based on ANOVA, there were significant differences of the available P and K, K+, Ca2+ and Mg2+ cations and electrical conductivity amongst the three forest types (p<0.05). Cluster analysis showed that the variations of the soil physico-chemical characteristics between the three forest types were low thus indicating that the soil physico-chemical investigated in this study were not the only main contributing factors in floristic variation of the three forest types in Chini watershed.
It is well-known that the characteristics of hardness and drillability are influenced by microstructure of rock. In this study, rock properties were analyzed on grain size and grain content. Coarse-grain and fine-grain sandstones were tested under successive indentation condition. Eighteen groups of sandstone and shale were employed for the drillability test. Indentation tests results showed that grain size influenced the low point of residual hardness, the crushing depth and volume and grain content influenced the peak point of hardness. The drillability values of shale increased with increasing contents of clay and quartz. Meanwhile, drillability values of sandstone increased with increasing content of quartz, but decreased with increasing content of clay. Therefore, these preliminary studies show great potential applications for selecting suitable bit type and formulating drilling program as a function of rock microstructure and crushing rock method for bit in the oil drilling.
The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen=bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, (1)H NMR, (13)C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.
This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application.
Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.
This paper presents the findings of a study on adsorption of dichlorodiphenythreechloroethen (DDT) and polychlorinated biphenyls (PCBs) on three nanomaterials including Multi walled Carbon Nanotube (MWNT), nano-clay and nano-alumina. DDT and PCBs are of significant concern due their high toxicity and long environmental half-lives. Experiments were conducted using batch adsorption procedures at different DDT and PCBs concentrations, from 10 to 60 mg/L. The amounts of MWNT, nano-clay and Nano-alumina used were 0.25%, 0.50%, 0.75%, 1%, 2% and 10%. The adsorption of PCBs solution onto the MWNT, nano-clay and nano-alumina was characterized by an initial rapid adsorption which eventually became constant within 22, 20, and 17 hours, respectively. The adsorption of DDT solution onto the MWNT, nano-clay and nano-alumina was also characterized by an initial rapid adsorption which gradually became constant within 22, 22 and 16 hours, respectively. Results of this study indicated that MWNT was a better adsorbent material compared to nano-clay and nano-alumina for both contaminants in this study. While at 10% of MWNT 88.9% and 77% of DDT and PCB were removed by MWNT, respectively. The effect of pH and temperature were also investigated.
In the current study, a sol-gel-synthesized tricalcium magnesium silicate powder was coated on Ti-6Al-4V alloys using plasma spray method. Composition of feed powder was evaluated by X-ray diffraction technique before and after the coating process. Scanning electron microscopy and atomic force microscopy were used to study the morphology of coated substrates. The corrosion behaviors of bare and coated Ti-6Al-4V alloys were examined using potentiodynamic polarization test and electrochemical impedance spectroscopy in stimulated body fluids. Moreover, bare and coated Ti-6Al-4V alloys were characterized in vitro by culturing osteoblast and mesenchymal stem cells for several days. Results demonstrated a meaningful improvement in the corrosion resistance of Ti-6Al-4V alloys coated with tricalcium magnesium silicate compared with the bare counterparts, by showing a decrease in corrosion current density from 1.84 μA/cm2 to 0.31 μA/cm2. Furthermore, the coating substantially improved the bioactivity of Ti-6Al-4Valloys. Our study on corrosion behavior and biological response of Ti-6Al-4V alloy coated by tricalcium magnesium silicate proved that the coating has considerably enhanced safety and applicability of Ti-6Al-4V alloys, suggesting its potential use in permanent implants and artificial joints.
This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.