Abstract: Alkylated silicon nanocrystals (C11-SiNCs) were
prepared successfully by galvanostatic etching of p-Si(100) wafers
followed by a thermal hydrosilation reaction of 1-undecene in
refluxing toluene in order to extract C11-SiNCs from porous silicon.
Erbium trichloride was added to alkylated SiNCs using a simple
mixing chemical route. To the best of our knowledge, this is the first
investigation on mixing SiNCs with erbium ions (III) by this
chemical method. The chemical characterization of C11-SiNCs and
their mixtures with Er3+(Er/C11-SiNCs) were carried out using X-ray
photoemission spectroscopy (XPS). The optical properties of C11-
SiNCs and their mixtures with Er3+ were investigated using Raman
spectroscopy and photoluminescence (PL). The erbium mixed
alkylated SiNCs shows an orange PL emission peak at around 595
nm that originates from radiative recombination of Si. Er/C11-SiNCs
mixture also exhibits a weak PL emission peak at 1536 nm that
originates from the intra-4f transition in erbium ions (Er3+). The PL
peak of Si in Er/C11-SiNCs mixture is increased in the intensity up to
three times as compared to pure C11-SiNCs. The collected data
suggest that this chemical mixing route leads instead to a transfer of
energy from erbium ions to alkylated SiNCs.
Abstract: Passing the entrance exam to a university is a major
step in one's life. University entrance exam commonly known as
Kankor is the nationwide entrance exam in Afghanistan. This
examination is prerequisite for all public and private higher education
institutions at undergraduate level. It is usually taken by students who
are graduated from high schools. In this paper, we reflect the major
educational school graduates issues and propose ICT-based test
preparation environment, known as ‘Online Kankor Exam Prep
System’ to give students the tools to help them pass the university
entrance exam on the first try. The system is based on Intelligent
Tutoring System (ITS), which introduced an essential package of
educational technology for learners that features: (I) exam-focused
questions and content; (ii) self-assessment environment; and (iii) test
preparation strategies in order to help students to acquire the necessary
skills in their carrier and keep them up-to-date with instruction.
Abstract: The objective of the present study is to determine
better eye end design of a mono leaf spring used in light motor
vehicle. A conventional 65Si7 spring steel leaf spring model with
standard eye, casted and riveted eye end are considered. The CAD
model of the leaf springs is prepared in CATIA and analyzed using
ANSYS. The standard eye, casted and riveted eye leaf springs are
subjected to similar loading conditions. The CAE analysis of the leaf
spring is performed for various parameters like deflection and Von-
Mises stress. Mass reduction of 62.9% is achieved in case of riveted
eye mono leaf spring as compared to standard eye mono leaf spring
for the same loading conditions.
Abstract: The problematic of gender and socioeconomic status
biased differences in academic motivation patterns is discussed.
Gender identity is understood according to symbolic interactionism
perspective: as a result of reflected appraisals, social comparisons,
self-attributions, and identifications, shaped by social environment
and family context. The effects of socioeconomic status on academic
motivation are conceptualized according to Bourdieu’s habitus
concept, reflecting the role of unconscious and internalized cultural
signals, proper to low and high socioeconomic status family contexts.
Since families differ by various socioeconomic features, the
hypothesis about possible impact of parents’ socioeconomic status on
their children’s academic motivation interfering with gender
socialization effects is held. The survey, aiming to seize gender
differences in academic motivation and self-recorded improvementoriented
efforts as a result of socialization processes operating in the
families of low and high socioeconomic status, was designed. The
results of Lithuanian higher education students’ survey are presented
and discussed.
Abstract: TiO2 thin films have been prepared by the sol-gel dipcoating
technique in order to elaborate antireflective thin films for
monocrystalline silicon (mono-Si). The titanium isopropoxyde was
chosen as a precursor with hydrochloric acid as a catalyser for
preparing a stable solution. The optical properties have been tailored
with varying the solution concentration, the withdrawn speed, and the
heat-treatment. We showed that using a TiO2 single layer with 64.5
nm in thickness, heat-treated at 450°C or 300°C reduces the mono-Si
reflection at a level lower than 3% over the broadband spectral
domains [669-834] nm and [786-1006] nm respectively. Those latter
performances are similar to the ones obtained with double layers of
low and high refractive index glasses respectively.
Abstract: This paper presents observations on the early
supervised internships in Psychology, currently called basic
internships in Brazil, and its importance in professional training. The
work is an experience report and focuses on the Professional training,
illustrated by the reality of a Brazilian institution, used as a case
study. It was developed from the authors' experience as academic
supervisors of this kind of practice throughout this undergraduate
course, combined with aspects investigated in the post-doctoral
research of one of them. Theoretical references on the subject and
related national legislation are analyzed, as well as reports of students
who experienced at least one semester of this type of practice,
articulated to the observations of the authors. The results demonstrate
the importance of the early supervised internships as a way of
creating opportunities for the students of a first contact with the
professional reality and the practice of psychologists in different
fields of insertion, preparing them for further experiments that require
more involvement in activities of training and practices in
Psychology.
Abstract: This work was one of the tasks of the
Manufacturing2Client project, whose objective was to develop a
frontal deflector to be commercialized in the automotive industry,
using new project and manufacturing methods. In this task, in
particular, it was proposed to develop the ability to predict
computationally the aerodynamic influence of flow in vehicles, in an
effort to reduce fuel consumption in vehicles from class 3 to 8. With
this aim, two deflector models were developed and their aerodynamic
performance analyzed. The aerodynamic study was done using the
Computational Fluid Dynamics (CFD) software Ansys CFX and
allowed the calculation of the drag coefficient caused by the vehicle
motion for the different configurations considered. Moreover, the
reduction of diesel consumption and carbon dioxide (CO2) emissions
associated with the optimized deflector geometry could be assessed.
Abstract: Rhodamine B (RB) is a toxic dye used extensively in
textile industry, which must be remediated before its drainage to
environment. In the present study, supported gold nanoparticles on
commercially available titania and zincite were successfully prepared
and then their activity on the photodegradation of RB under UV A
light irradiation were evaluated. The synthesized photocatalysts were
characterized by ICP, BET, XRD, and TEM. Kinetic results showed
that Au/TiO2 was an inferior photocatalyst to Au/ZnO. This
observation could be attributed to the strong reflection of UV
irradiation by gold nanoparticles over TiO2 support.
Abstract: Excavation and retaining walls are of challenging
issues in civil engineering. In this study, the behavior of one
important type of supporting systems called Contiguous Bored Pile
(CBP) retaining wall is investigated using a physical model. Besides,
a comparison is made between two modes of free end piles (soft bed)
and fixed end piles (stiff bed). Also a back calculation of effective
length (the real free length of pile) is done by measuring lateral
deflection of piles in different stages of excavation in both
aforementioned cases. Based on observed results, for the fixed end
mode, the effective length to free length ratio (Leff/L0) is equal to
unity in initial stages of excavation and less than 1 in its final stages
in a decreasing manner. While this ratio for free end mode, remains
constant during all stages of excavation and is always less than unity.
Abstract: In EFL programs, rating scales used in writing
assessment are often constructed by intuition. Intuition-based scales
tend to provide inaccurate and divisive ratings of learners’ writing
performance. Hence, following an empirical approach, this study
attempted to develop a rating scale for elementary-level writing at an
EFL program in Saudi Arabia. Towards this goal, 98 students’ essays
were scored and then coded using comprehensive taxonomy of
writing constructs and their measures. An automatic linear modeling
was run to find out which measures would best predict essay scores.
A nonparametric ANOVA, the Kruskal-Wallis test, was then used to
determine which measures could best differentiate among scoring
levels. Findings indicated that there were certain measures that could
serve as either good predictors of essay scores or differentiators
among scoring levels, or both. The main conclusion was that a rating
scale can be empirically developed using predictive and
discriminative statistical tests.
Abstract: We report on the use of strong external optical
feedback to enhance the modulation response of semiconductor lasers
over a frequency passband around modulation frequencies higher
than 60 GHz. We show that this modulation enhancement is a type of
photon-photon resonance (PPR) of oscillating modes in the external
cavity formed between the laser and the external reflector. The study
is based on a time-delay rate equation model that takes into account
both the strong feedback and multiple reflections in the external
cavity. We examine the harmonic and intermodulation distortions
associated with single and two-tone modulations in the mm-wave
band of the resonant modulation. We show that compared with
solitary lasers modulated around the carrier-photon resonance
frequency, the present mm-wave modulated signal has lower
distortions.
Abstract: This paper focuses on the dynamic behavior of
reinforced concrete (RC) slabs. Therefore, the theoretical modal
analysis was performed using two different types of boundary
conditions. Modal analysis method is the most important dynamic
analyses. The analysis would be modal case when there is no external
force on the structure. By using this method in this paper, the effects
of freely and simply supported boundary conditions on the
frequencies and mode shapes of RC square slabs are studied. ANSYS
software was employed to derive the finite element model to
determine the natural frequencies and mode shapes of the slabs.
Then, the obtained results through numerical analysis (finite element
analysis) would be compared with the exact solution. The main goal
of the research study is to predict how the boundary conditions
change the behavior of the slab structures prior to performing
experimental modal analysis. Based on the results, it is concluded
that simply support boundary condition has obvious influence to
increase the natural frequencies and change the shape of the mode
when it is compared with freely supported boundary condition of
slabs. This means that such support conditions have the direct
influence on the dynamic behavior of the slabs. Thus, it is suggested
to use free-free boundary condition in experimental modal analysis to
precisely reflect the properties of the structure. By using free-free
boundary conditions, the influence of poorly defined supports is
interrupted.
Abstract: This paper illustrates the effect of nano Magnesium
Hydroxide (MH) loading on the thermal properties of Low Density
Polyethylene (LDPE)/Poly (ethylene-co vinyl acetate) (EVA) nano
composite. Thermal studies were conducted, as it understanding is
vital for preliminary development of new polymeric systems.
Thermal analysis of nanocomposite was conducted using thermo
gravimetric analysis (TGA), and differential scanning calorimetry
(DSC). Major finding of TGA indicated two main stages of
degradation process found at (350 ± 25oC) and (480 ± 25oC)
respectively. Nano metal filler expressed better fire resistance as it
stand over high degree of temperature. Furthermore, DSC analysis
provided a stable glass temperature around 51 (±1oC) and captured
double melting point at 84 (±2oC) and 108 (±2oC). This binary
melting point reflects the modification of nano filler to the polymer
matrix forming melting crystals of folded and extended chain. The
percent crystallinity of the samples grew vividly with increasing filler
content. Overall, increasing the filler loading improved the
degradation temperature and weight loss evidently and a better
process and phase stability was captured in DSC.
Abstract: Aim of this work was to study the genetic basis for oil
accumulation in olive fruit via tracking DGAT2 (Diacylglycerol
acyltransferase type-2) gene in three Egyptian Origen Olive cultivars
namely Toffahi, Hamed and Maraki using molecular marker
techniques and bioinformatics tools. Results illustrate that, firstly:
specific genomic band of Maraki cultivars was identified as DGAT2
(Diacylglycerol acyltransferase type-2) and identical for this gene in
Olea europaea with 100% of similarity. Secondly, differential
genomic band of Maraki cultivars which produced from RAPD
fingerprinting technique reflected predicted distinguished sequence
which identified as DGAT2 (Diacylglycerol acyltransferase type-2)
in Fragaria vesca subsp. Vesca with 76% of sequential similarity.
Third and finally, specific genomic specific band of Hamed cultivars
was identified as two fragments, 1- Olea europaea cultivar Koroneiki
diacylglycerol acyltransferase type 2 mRNA, complete cds with two
matches regions with 99% or 2- Predicted: Fragaria vesca subsp.
vesca diacylglycerol O-acyltransferase 2-like (LOC101313050),
mRNA with 86 % of similarity.
Abstract: Many problems in science and engineering field require
the solution of shifted linear systems with multiple right hand
sides and multiple shifts. To solve such systems efficiently, the
implicitly restarted global GMRES algorithm is extended in this
paper. However, the shift invariant property could no longer hold over
the augmented global Krylov subspace due to adding the harmonic
Ritz matrices. To remedy this situation, we enforce the collinearity
condition on the shifted system and propose shift implicitly restarted
global GMRES. The new method not only improves the convergence
but also has a potential to simultaneously compute approximate
solution for the shifted systems using only as many matrix vector
multiplications as the solution of the seed system requires. In
addition, some numerical experiments also confirm the effectiveness
of our method.
Abstract: This work is focused on the study of valuation of
recycled concrete aggregates, by measuring certain properties of
concrete in the fresh and hardened state. In this study, rheological
tests and physic-mechanical characterization on concretes and
mortars were conducted with recycled concrete whose geometric
properties were identified aggregates. Mortars were elaborated with
recycled fine aggregate (0/5mm) and concretes were manufactured
using recycled coarse aggregates (5/12.5 mm and 12.5/20 mm). First,
a study of the mortars was conducted to determine the effectiveness
of polycarboxylate superplasticizer on the workability of these and
their action deflocculating of the recycled sand. The rheological
behavior of mortars based on fine aggregate recycled was
characterized. The results confirm that the mortars composed of
different fractions of recycled sand (0 /5) have a better mechanical
properties (compressive and flexural strength) compared to normal
mortar. Also, the mechanical strengths of concretes made with
recycled aggregates (5/12.5 mm and 12.5/20 mm), are comparable to
those of conventional concrete with conventional aggregates,
provided that the implementation can be improved by the addition of
a superplasticizer.
Abstract: The efficiency of wood vinegar mixed with each
individual of three plants extract such as: citronella grass
(Cymbopogon nardus), neem seed (Azadirachta indica A. Juss), and
yam bean seed (Pachyrhizus erosus Urb.) were tested against the
second instar larvae of housefly (Musca domestica L.). Steam
distillation was used for extraction of the citronella grass while neem
and yam bean were simple extracted by fermentation with ethyl
alcohol. Toxicity test was evaluated in laboratory based on two
methods of larvicidal bioassay: topical application method (contact
poison) and feeding method (stomach poison). Larval mortality was
observed daily and larval survivability was recorded until the
survived larvae developed to pupae and adults. The study resulted
that treatment of wood vinegar mixed with citronella grass showed
the highest larval mortality by topical application method (50.0%)
and by feeding method (80.0%). However, treatment of mixed wood
vinegar and neem seed showed the longest pupal duration to 25 day
and 32 days for topical application method and feeding method
respectively. Additional, larval duration on treated M. domestica
larvae was extended to 13 days for topical application method and 11
days for feeding method. Thus, the feeding method gave higher
efficiency compared with the topical application method.
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: Supermarkets are the most electricity-intensive type of
commercial buildings. The unsuitable indoor environment of a
supermarket provided by abnormal HVAC operations incurs waste
energy consumption in refrigeration systems. This current study
briefly describes significantly solid backgrounds and proposes easyto-
use analysis terminology for investigating the impact of HVAC
operations on refrigeration power consumption using the field-test
data obtained from building automation system (BAS). With solid
backgrounds and prior knowledge, expected energy interactions
between HVAC and refrigeration systems are proposed through
Pearson’s correlation analysis (R value) by considering correlations
between equipment power consumption and dominantly independent
variables (driving force conditions).The R value can be conveniently
utilized to evaluate how strong relations between equipment
operations and driving force parameters are. The calculated R values
obtained from field data are compared to expected ranges of R values
computed by energy interaction methodology. The comparisons can
separate the operational conditions of equipment into faulty and
normal conditions. This analysis can simply investigate the condition
of equipment operations or building sensors because equipment could
be abnormal conditions due to routine operations or faulty
commissioning processes in field tests. With systematically solid and
easy-to-use backgrounds of interactions provided in the present
article, the procedures can be utilized as a tool to evaluate the proper
commissioning and routine operations of HVAC and refrigeration
systems to detect simple faults (e.g. sensors and driving force
environment of refrigeration systems and equipment set-point) and
optimize power consumption in supermarket buildings. Moreover,
the analysis will be used to further study the FDD research for
supermarkets in future.
Abstract: The present study debates students’ perceptions of the
use of technology in learning English as a Foreign Language. Its aim
is to explore and understand students’ preparation and presentation of
Posters, PowerPoint and Animated Videos by drawing attention to
visual and oral elements. The data is collected through observations
and semi-structured interviews and analyzed through
phenomenological data analysis steps. The themes emerged from the
data, visual learning satisfaction in using information and
communication technology, providing structure to oral presentation,
learning from peers’ presentations, draw attention to using Posters,
PowerPoint and Animated Videos as each supports visual learning
and organization of thoughts in oral presentations.