Abstract: Nitrogen-doped graphene quantum dots (N-GQDs)
were fabricated by microwave-assisted hydrothermal technique. The
optical properties of the N-GQDs were studied. The luminescence of
the N-GQDs can be tuned by varying the excitation wavelength.
Furthermore, two-photon luminescence of the N-GQDs excited by
near-infrared laser can be obtained. It is shown that N-doping play a
key role on two-photon luminescence. The N-GQDs are expected to
find application in biological applications including bioimaging and
sensing.
Abstract: The knowledge of biodiesel density over large ranges
of temperature and pressure is important for predicting the behavior
of fuel injection and combustion systems in diesel engines, and for
the optimization of such systems. In this study, cottonseed oil was
transesterified into biodiesel and its density was measured at
temperatures between 288 K and 358 K and pressures between 0.1
MPa and 30 MPa, with expanded uncertainty estimated as ±1.6 kg⋅m-
3. Experimental pressure-volume-temperature (pVT) cottonseed data
was used along with literature data relative to other 18 biodiesels, in
order to build a database used to test the correlation of density with
temperarure and pressure using the Goharshadi–Morsali–Abbaspour
equation of state (GMA EoS). To our knowledge, this is the first that
density measurements are presented for cottonseed biodiesel under
such high pressures, and the GMA EoS used to model biodiesel
density. The new tested EoS allowed correlations within 0.2 kg·m-3
corresponding to average relative deviations within 0.02%. The built
database was used to develop and test a new full predictive model
derived from the observed linear relation between density and degree
of unsaturation (DU), which depended from biodiesel FAMEs
profile. The average density deviation of this method was only about
3 kg.m-3 within the temperature and pressure limits of application.
These results represent appreciable improvements in the context of
density prediction at high pressure when compared with other
equations of state.
Abstract: Nanostructured catalysts were successfully prepared
by acidification of diatomite and regeneration of FCC spent catalysts.
The obtained samples were characterized by IR, XRD, SEM, EDX,
MAS-NMR (27Al and 29Si), NH3-TPD and tested in catalytic
pyrolysis of biomass (rice straw). The results showed that the similar
bio-oil yield of 41.4% can be obtained by pyrolysis with catalysts at
450oC as compared to that of the pyrolysis without catalyst at 550oC.
The bio-oil yield reached a maximum of 42.55% at the pyrolysis
temperature of 500oC with catalytic content of 20%. Moreover, by
catalytic pyrolysis, bio-oil quality was better as reflected in higher
ratio of H/C, lower ratio of O/C. This clearly indicated high
application potential of these new nanostructured catalysts in the
production of bio-oil with low oxygenated compounds.
Abstract: The influence of three different types of halloysite
nanotubes (HNTs) with different dimensions, namely as camel lake
(CLA), Jarrahdale (JA) and Matauri Bay (MB), on their reinforcing
ability of ethylene propylene dine monomer (EPDM) were
investigated by varying the HNTs loading (from 0-15 phr).
Mechanical properties of the nanocomposites improved with addition
of all three HNTs, but CLA based nanocomposites exhibited a
significant enhancement compared to the other HNTs. For instance,
tensile properties of EPDM nanocomposites increased by 120%,
256% and 340% for MB, JA and CLA, respectively, with addition of
15 phr of HNTs. This could be due to the higher aspect ratio and
higher surface area of CLA compared to others. Scanning electron
microscopy (SEM) of nanocomposites at 15 phr of HNT loadings
showed low amounts of pulled-out nanotubes which confirmed the
presence of more embedded nanotubes inside the EPDM matrix, as
well as aggregates within the fracture surface of EPDM/HNT
nanocomposites
Abstract: Magnetic powder of Sr-ferrite was prepared by
conventional and sol-gel auto-combustion methods. In conventional
method, strontium carbonate and ferric oxide powders were mixed
together and then mixture was calcined. In sol-gel auto-combustion
method, a solution containing strontium nitrate, ferric nitrate and
citric acid was heated until the combustion took place automatically;
then, as-burnt powder was calcined. Thermal behavior, phase
identification, morphology and magnetic properties of powders
obtained by these two methods were compared by DTA, XRD, SEM
and VSM techniques. According to the results of DTA analysis,
formation temperature of Sr-ferrite obtained by conventional and solgel
auto-combustion methods were 1300°C and 1000°C, respectively.
XRD results confirmed the formation of pure Sr-ferrite at the
mentioned temperatures. Plate and hexagonal-shape particles of Srferrite
were observed using SEM. The Sr-ferrite powder obtained by
sol-gel auto-combustion method had saturation magnetization of
66.03 emu/g and coercivity of 5731 Oe in comparison with values of
58.20 emu/g and 4378 Oe obtained by conventional method.
Abstract: A series of polystyrene (PS) nanoparticles were
prepared by grafting polystyrene from both aggregated silica and
colloidally dispersed silica nanoparticles using atom-transfer radical
polymerisation (ATRP). Cross-linking and macroscopic gelation
were minimised by using a miniemulsion system. The thermal and
mechanical behaviour of the nanocomposites have been examined by
differential scanning calorimetry (DSC) and dynamic mechanical
thermal analysis (DMTA).
Abstract: Calcium phosphate cement (CPC) is one of the most
attractive bioceramics due to its moldable and shape ability to fill
complicated bony cavities or small dental defect positions. In this
study, CPC was produced by using mixture of tetracalcium phosphate
(TTCP, Ca4O(PO4)2) and dicalcium phosphate anhydrous (DCPA,
CaHPO4) in equimolar ratio (1/1) with aqueous solutions of acetic
acid (C2H4O2) and disodium hydrogen phosphate dehydrate
(Na2HPO4.2H2O) in combination with sodium alginate in order to
improve theirs moldable characteristic. The concentration of the
aqueous solutions and sodium alginate were varied to investigate the
effect of different aqueous solutions and alginate on properties of the
cements. The cement paste was prepared by mixing cement powder
(P) with aqueous solution (L) in a P/L ratio of 1.0g/0.35ml. X-ray
diffraction (XRD) was used to analyses phase formation of the
cements. Setting time and compressive strength of the set CPCs were
measured using the Gilmore apparatus and Universal testing
machine, respectively.
The results showed that CPCs could be produced by using both
basic (Na2HPO4.2H2O) and acidic (C2H4O2) solutions. XRD results
show the precipitation of hydroxyapatite in all cement samples. No
change in phase formation among cements using difference
concentrations of Na2HPO4.2H2O solutions. With increasing
concentration of acidic solutions, samples obtained less
hydroxyapatite with a high dicalcium phosphate dehydrate leaded to
a shorter setting time. Samples with sodium alginate exhibited higher
crystallization of hydroxyapatite than that of without alginate as a
result of shorten setting time in a basic solution but a longer setting
time in an acidic solution. The stronger cement was attained from
samples using the acidic solution with sodium alginate; however the
strength was lower than that of using the basic solution.
Abstract: Heightened concerns over the amount of carbon
emitted from coal-related processes are generating shifts to the
application of biomass. In co-gasification, where coal is gasified
along with biomass, the biomass may be fed together with coal (cofeeding)
or an independent biomass gasifier needs to be integrated
with the coal gasifier. The main aim of this work is to evaluate the
biomass introduction methods in coal co-gasification. This includes
the evaluation of biomass concentration input (B0 to B100) and its
gasification performance. A process model is developed and
simulated in Aspen HYSYS, where both coal and biomass are
modelled according to its ultimate analysis. It was found that the
syngas produced increased with increasing biomass content for both
co-feeding and independent schemes. However, the heating values
and heat duties decreases with biomass concentration as more CO2
are produced from complete combustion.
Abstract: Preparation of nanoparticles of cerium oxide and
adsorption of bovine serum albumin on them were studied. Particle
size distribution and influence of pH on zeta potential of prepared
CeO2 were determined. Average size of prepared cerium oxide
nanoparticles was 9 nm. The simultaneous measurements of the
bovine serum albumin adsorption and zeta potential determination of
the (adsorption) suspensions were carried out. The adsorption
isotherms were found to be of typical Langmuir type; values of the
bovine serum albumin adsorption capacities were calculated.
Increasing of pH led to decrease of zeta potential and decrease of
adsorption capacity of cerium oxide nanoparticles. The maximum
adsorption capacity was found for strongly acid suspension (am =
118 mg/g). The samples of nanoceria with positive zeta potential
adsorbed more bovine serum albumin on the other hand, the samples
with negative zeta potential showed little or no protein adsorption.
Surface charge or better say zeta potential of CeO2 nanoparticles
plays the key role in adsorption of proteins on such type of materials.
Abstract: Present study is aimed on the cutting process of circular
cross-section rods where the fracture is used to separate one rod
into two pieces. Incorporating the phenomenological ductile fracture
model into the explicit formulation of finite element method, the
process can be analyzed without the necessity of realizing too many
real experiments which could be expensive in case of repetitive
testing in different conditions. In the present paper, the steel AISI
1045 was examined and the tensile tests of smooth and notched
cylindrical bars were conducted together with biaxial testing of the
notched tube specimens to calibrate material constants of selected
phenomenological ductile fracture models. These were implemented
into the Abaqus/Explicit through user subroutine VUMAT and used
for cutting process simulation. As the calibration process is based
on variables which cannot be obtained directly from experiments,
numerical simulations of fracture tests are inevitable part of the
calibration. Finally, experiments regarding the cutting process were
carried out and predictive capability of selected fracture models is
discussed. Concluding remarks then make the summary of gained
experience both with the calibration and application of particular
ductile fracture criteria.
Abstract: Hydrogenated amorphous carbon (a-C:H) films have
been synthesized by a radio frequency plasma enhanced chemical
vapor deposition (rf-PECVD) technique with different bias voltage
from 0.0 to -0.5 kV. The Raman spectra displayed the polymer-like
hydrogenated amorphous carbon (PLCH) film with 0.0 to -0.1 and
a-C:H films with -0.2 to -0.5 kV of bias voltages. The surface chemical
information of all films were studied by X-ray photoelectron
spectroscopy (XPS) technique, presented to C-C (sp2 and sp3) and C-O
bonds, and relative carbon (C) and oxygen (O) atomics contents. The
O contamination had affected on structure and optical properties. The
true density of PLCH and a-C:H films were characterized by X-ray
refractivity (XRR) method, showed the result as in the range of
1.16-1.73 g/cm3 that depending on an increasing of bias voltage. The
hardness was proportional to the true density of films. In addition, the
optical properties i.e. refractive index (n) and extinction coefficient (k)
of these films were determined by a spectroscopic ellipsometry (SE)
method that give formation to in 1.62-2.10 (n) and 0.04-0.15 (k)
respectively. These results indicated that the optical properties
confirmed the Raman results as presenting the structure changed with
applied bias voltage increased.
Abstract: Aluminium and its alloys have excellent corrosion
resistant properties, ease of fabrication and high specific strength to
weight ratio. In this investigation an attempt has been made to study
the effect of different post weld heat treatment methods on the
mechanical and metallurgical properties of TIG welded joints of the
commercial aluminium alloy. Three different methods of post weld
heat treatments are solution heat treatment, artificial ageing and
combination of solution heat treatment and artificial aging are given
to TIG welded aluminium joints. Mechanical and metallurgical
properties of As welded joints of the aluminium alloys and post weld
heat treated joints of the aluminium alloys were examined.
Abstract: Esterification of p-bromo-m-cresol led to formation of
2-(4-bromo-3-methylphenoxy)acetate (1). 2-(4-Bromo-3-methyl
phenoxy)acetohydrazide (2) is derived from Compound (1) by
hydrazination. Compound (2) was reacted with different aromatic
aldehydes to yield N-(substituted benzylidiene)-2-(4-bromo-3-methyl
phenoxy)acetamide(3a-c). Cyclization of compound (3a-c) with
thioglycolic acid yielded 2-(4-bromo-3-methylphenoxy)-N-(4-oxo-2-
arylthiazolidin-3-yl) acetamide (4a-c). The newly synthesized
compounds were characterized on the basis of spectral studies and
evaluated for antibacterial and antifungal activities.
Abstract: This experimental study aims at studying the
conversion of macro-algae into bioethanol under several steps of
procedure: preparation, pre-treatment, fermentation, and distillation.
The main objective of this work was to investigate the role of buffer’s
type as a stabiliser of pH level and fermentation time on the yield of
ethanol. For this purpose, experiments were carried out on biomass
macro-algae to de-couple the pre-treatment and fermentation
processes from those associated with distillation process. β-
glucosidase was used as cellulose decomposer during hydrolysis step
and yeast was used during fermentation process. The species of
macro-algae utilised as energy feedstock was Ulva lactuca and it was
harvested from southern coast of Central of Java Island – Indonesia.
Experiments were conducted in a simple fermenter over a different
buffer: citrate buffer and acetic buffer, and over a range of
fermentation times between 5 to 20 days. The ethanol production was
found to be significantly affected by both variables. The optimum
time of fermentation was 10 days with citrate buffer; result in
0.88458% of ethanol, and the ethanol content after distillation
process was shown 0.985015%.
Abstract: In the present study, we have synthesized Cr and Fe
doped zinc oxide (ZnO) nanostructures (Zn1-δCraFebO; where δ = a +
b = 20%, a = 5, 6, 8 & 10% and b = 15, 14, 12 & 10%) via sol-gel
method at different doping concentrations. The synthesized samples
were characterized for structural properties by X-ray diffractrometer
and field emission scanning electron microscope and the optical
properties were carried out through photoluminescence and UVvisible
spectroscopy. The particle size calculated through field
emission scanning electron microscope varies from 41 to 96 nm for
the samples synthesized at different doping concentrations. The
optical band gaps calculated through UV-visible spectroscopy are
found to be decreasing from 3.27 to 3.02 eV as the doping
concentration of Cr increases and Fe decreases.
Abstract: Stress Corrosion Crack (SCC) in pipeline is a type of
environmentally assisted cracking (EAC), since its discovery in 1965
as a possible cause of failure in pipeline, SCC has caused, on
average, one of two failures per year in the U.S, According to the
NACE SCC DA a pipe line segment is considered susceptible to SCC
if all of the following factors are met: The operating stress exceeds
60% of specified minimum yield strength (SMYS), the operating
temperature exceeds 38°C, the segment is less than 32 km
downstream from a compressor station, the age of the pipeline is
greater than 10 years and the coating type is other than Fusion
Bonded Epoxy(FBE). In this paper as a practical experience in
NISOC, Direct Assessment (DA) Method is used for identification
SCC defect in unpiggable pipeline located downstream of
compressor station.
Abstract: Kuosheng nuclear power plant (NPP) is a BWR/6 type
NPP and located on the northern coast of Taiwan. First, Kuosheng
NPP TRACE model were developed in this research. In order to assess
the system response of Kuosheng NPP TRACE model, startup tests
data were used to evaluate Kuosheng NPP TRACE model. Second, the
overpressurization transient analysis of Kuosheng NPP TRACE model
was performed. Besides, in order to confirm the mechanical property
and integrity of fuel rods, FRAPTRAN analysis was also performed in
this study.
Abstract: A noble low NOx combustion technology, based on
partial oxidation combustion concept in a fuel rich combustion zone, is
successfully applied in this research. The burner is designed such that
a portion of fuel is heated and pre-vaporized in the furnace then
injected into a fuel rich combustion zone so that a partial oxidation
reaction occurs. The effects of equivalence ratio, thermal load, and
fuel distribution ratio on the emissions of NOx and CO are
experimentally investigated. This newly developed combustion
technology showed very low NOx emission level, about 12 ppm, when
light oil is used as a fuel.
Abstract: Folic acid (FA) is known to be an important
supplement to prevent neural tube defect (NTD) in pregnant women.
Similar to some commercial formulations, sodium bicarbonate
solution is used as a solvent for FA. This work uses the antisolvent
vapour precipitation (AVP), incorporating ethanol vapour as the
convective drying medium in place of air to produce branch-like
micro-structure FA particles. Interestingly, the dissolution rate of the
resultant particle is 2-3 times better than the particle produce from
conventional air drying due to the higher surface area of particles
produced. The higher dissolution rate could possibly improve the
delivery and absorption of FA in human body. This application could
potentially be extended to other commercial products, particularly in
less soluble drugs to improve its solubility.
Abstract: In the present work, hydrogen gas sensor of modest
sensitivity utilizing functionalized multiwalled carbon nanotubes
partially decorated with tin oxide nanoparticles (F-MWCNTs/SnO2)
has been fabricated. This sensing material was characterized by
scanning electron microscopy (SEM). In addition, a remarkable
finding was that the F-MWCNTs/SnO2 sensor shows good sensitivity
as compared to F-MWCNTs for low concentration (0.05-1% by
volume) of H2 gas. The fabricated sensors show complete resistance
recovery and good repeatability when exposed to H2 gas at the room
temperature conditions.