Abstract: Thermal insulating composites help to reduce the total power consumption in a building by creating a barrier between external and internal environment. Such composites can be used in the roofing tiles or wall panels for exterior surfaces. This study purposes to develop lightweight cement-based composites for thermal insulating applications. Waste materials like silica fume (an industrial by-product) and fly ash cenosphere (FAC) (hollow micro-spherical shells obtained as a waste residue from coal fired power plants) were used as partial replacement of cement and lightweight filler, respectively. Moreover, aerogel, a nano-porous material made of silica, was also used in different dosages for improved thermal insulating behavior, while poly vinyl alcohol (PVA) fibers were added for enhanced toughness. The raw materials including binders and fillers were characterized by X-Ray Diffraction (XRD), X-Ray Fluorescence spectroscopy (XRF), and Brunauer–Emmett–Teller (BET) analysis techniques in which various physical and chemical properties of the raw materials were evaluated like specific surface area, chemical composition (oxide form), and pore size distribution (if any). Ultra-lightweight cementitious composites were developed by varying the amounts of FAC and aerogel with 28-day unit weight ranging from 1551.28 kg/m3 to 1027.85 kg/m3. Excellent mechanical and thermal insulating properties of the resulting composites were obtained ranging from 53.62 MPa to 8.66 MPa compressive strength, 9.77 MPa to 3.98 MPa flexural strength, and 0.3025 W/m-K to 0.2009 W/m-K as thermal conductivity coefficient (QTM-500). The composites were also tested for peak temperature difference between outer and inner surfaces when subjected to heating (in a specially designed experimental set-up) by a 275W infrared lamp. The temperature difference up to 16.78 oC was achieved, which indicated outstanding properties of the developed composites to act as a thermal barrier for building envelopes. Microstructural studies were carried out by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) for characterizing the inner structure of the composite specimen. Also, the hydration products were quantified using the surface area mapping and line scale technique in EDS. The microstructural analyses indicated excellent bonding of FAC and aerogel in the cementitious system. Also, selective reactivity of FAC was ascertained from the SEM imagery where the partially consumed FAC shells were observed. All in all, the lightweight fillers, FAC, and aerogel helped to produce the lightweight composites due to their physical characteristics, while exceptional mechanical properties, owing to FAC partial reactivity, were achieved.
Abstract: Organic compounds in wastewaters coming from textile and pharmaceutical industry generated multiple harmful effects on the environment and the human health. One of them is the methyl orange (MeO), an azoic dye considered to be a recalcitrant compound. The heterogeneous photocatalysis emerges as an alternative for treating this type of hazardous compounds, through the generation of OH radicals using radiation and a semiconductor oxide. According to the author’s knowledge, catalysts such as TiO2 doped with metals show high efficiency in degrading MeO; however, this presents economic limitations on industrial scale. Black sand can be considered as a naturally doped catalyst because in its structure is common to find compounds such as titanium, iron and aluminum oxides, also elements such as zircon, cadmium, manganese, etc. This study reports the photocatalytic activity of the mineral black sand used as semiconductor in the discoloration of MeO by oxidation and reduction photocatalytic techniques. For this, magnetic composites from the mineral were prepared (RM, M1, M2 and NM) and their activity were tested through MeO discoloration while TiO2 was used as reference. For the fractions, chemical, morphological and structural characterizations were performed using Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX), X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analysis. M2 fraction showed higher MeO discoloration (93%) in oxidation conditions at pH 2 and it could be due to the presence of ferric oxides. However, the best result to reduction process was using M1 fraction (20%) at pH 2, which contains a higher titanium percentage. In the first process, hydrogen peroxide (H2O2) was used as electron donor agent. According to the results, black sand mineral can be used as natural semiconductor in photocatalytic process. It could be considered as a photocatalyst precursor in such processes, due to its low cost and easy access.
Abstract: In this paper, the mechanism of stratified liquids’ mixing in a cylinder is investigated. It is focused on the effects of Rayleigh-Taylor Instability (RTI) and rotation of the cylinder on liquid interface mixing. For miscible liquids, Planar Laser Induced Fluorescence (PLIF) technique is applied to record the concentration field for one liquid. Intensity of Segregation (IOS) is used to describe the mixing status. For immiscible liquids, High Speed Camera is adopted to record the development of the interface. The experiment of RTI indicates that it plays a great role in the mixing process, and meanwhile the large-scale mixing is triggered, and subsequently the span of the stripes decreases, showing that the mesoscale mixing is coming into being. The rotation experiments show that the spin-down process has a great role in liquid mixing, during which the upper liquid falls down rapidly along the wall and crashes into the lower liquid. During this process, a lot of interface instabilities are excited. Liquids mix rapidly in the spin-down process. It can be concluded that no matter what ways have been adopted to speed up liquid mixing, the fundamental reason is the interface instabilities which increase the area of the interface between liquids and increase the relative velocity of the two liquids.
Abstract: The paper examines the mechanism of pozzolan-soil reactions, using a recent study on the chemical stabilization of a Class A-2-7 (3) lateritic soil, with corn cob ash (CCA) as case study. The objectives are to establish a nexus between cation exchange capacity of the soil, the alkaline forming compounds in CCA and percentage CCA addition to soil beyond which no more improvement in strength properties can be achieved; and to propose feasible chemical reactions to explain the chemical stabilization of the lateritic soil with CCA alone. The lateritic soil, as well as CCA of pozzolanic quality Class C were separately analysed for their metallic oxide composition using the X-Ray Fluorescence technique. The cation exchange capacity (CEC) of the soil and the CCA were computed theoretically using the percentage composition of the base cations Ca2+, Mg2+ K+ and Na2+ as 1.48 meq/100 g and 61.67 meq/100 g respectively, thus indicating a ratio of 0.024 or 2.4%. This figure, taken as the theoretical amount required to just fill up the exchangeable sites of the clay molecules, compares well with the laboratory observation of 1.5% for the optimum level of CCA addition to lateritic soil. The paper went on to present chemical reaction equations between the alkaline earth metals in the CCA and the silica in the lateritic soil to form silicates, thereby proposing an extension of the theory of mechanism of soil stabilization to cover chemical stabilization with pozzolanic ash only. The paper concluded by recommending further research on the molecular structure of soils stabilized with pozzolanic waste ash alone, with a view to confirming the chemical equations advanced in the study.
Abstract: Reverse osmosis (RO) membranes have been widely used for desalination to purify water for drinking and other purposes. Although at present most RO membranes have no resistance to chlorine, chlorine-resistant membranes are being developed. Therefore, direct chlorine treatment or chlorine washing will be an option in preventing biofouling on chlorine-resistant membranes. Furthermore, if particle accumulation control is possible by using chlorine washing, expensive pretreatment for particle removal can be removed or simplified. The objective of this study was to determine the effective hypochlorite washing condition required for controlling biofilm formation and inorganic particle accumulation on RO membrane in a continuous flow channel with RO membrane and spacer. In this study, direct chlorine washing was done by soaking fouled RO membranes in hypochlorite solution and fluorescence intensity was used to quantify biofilm on the membrane surface. After 48 h of soaking the membranes in high fouling potential waters, the fluorescence intensity decreased to 0 from 470 using the following washing conditions: 10 mg/L chlorine concentration, 2 times/d washing interval, and 30 min washing time. The chlorine concentration required to control biofilm formation decreased as the chlorine concentration (0.5–10 mg/L), the washing interval (1–4 times/d), or the washing time (1–30 min) increased. For the sample solutions used in the study, 10 mg/L chlorine concentration with 2 times/d interval, and 5 min washing time was required for biofilm control. The optimum chlorine washing conditions obtained from soaking experiments proved to be applicable also in controlling biofilm formation in continuous flow experiments. Moreover, chlorine washing employed in controlling biofilm with suspended particles resulted in lower amounts of organic (0.03 mg/cm2) and inorganic (0.14 mg/cm2) deposits on the membrane than that for sample water without chlorine washing (0.14 mg/cm2 and 0.33 mg/cm2, respectively). The amount of biofilm formed was 79% controlled by continuous washing with 10 mg/L of free chlorine concentration, and the inorganic accumulation amount decreased by 58% to levels similar to that of pure water with kaolin (0.17 mg/cm2) as feed water. These results confirmed the acceleration of particle accumulation due to biofilm formation, and that the inhibition of biofilm growth can almost completely reduce further particle accumulation. In addition, effective hypochlorite washing condition which can control both biofilm formation and particle accumulation could be achieved.
Abstract: This study is aimed to investigate the influence of
postharvest delays of 1-Methylcyclopropene (1-MCP) treatment on
prolonging the storage potential of melon. Melons were treated with
625-650 ppb 1-MCP at 10 °C for 24 hours on the 1st, 3rd and 5th day
after harvest. Decreased ethylene production and retarded softening
of melon fruits after 7 days of storage at 10 °C plus 3 days of shelflife
were obtained by 1-MCP applications. 1-MCP strongly affected
the chlorophyll fluorescence characteristics and hue angle values of
melon. After shelf-life, the peel color of treated melon was slow in
turning to yellow compared to the control. Additionally, firmness of
melons treated on the first day after harvest was 38% higher than that
of the control fruit. Results showed that fruits treated on the 1st and
the 3rd day after harvest could maintain the quality of melon.
Abstract: A novel sensing system has been designed for
naphthalene detection based on the quenched fluorescence signal of
CdS quantum dots. The fluorescence intensity of the system reduced
significantly after adding CdS quantum dots to the water pollution
model because of the fluorescent static quenching f mechanism.
Herein, we have demonstrated the facile methodology can offer a
convenient and low analysis cost with the recovery rate as
97.43%-103.2%, which has potential application prospect.
Abstract: Online measurement of the product quality is a
challenging task in cement production, especially in the production of
Celitement, a novel environmentally friendly hydraulic binder. The
mineralogy and chemical composition of clinker in ordinary Portland
cement production is measured by X-ray diffraction (XRD) and
X-ray fluorescence (XRF), where only crystalline constituents can be
detected. But only a small part of the Celitement components can be
measured via XRD, because most constituents have an amorphous
structure. This paper describes the development of algorithms
suitable for an on-line monitoring of the final processing step of
Celitement based on NIR-data. For calibration intermediate products
were dried at different temperatures and ground for variable
durations. The products were analyzed using XRD and
thermogravimetric analyses together with NIR-spectroscopy to
investigate the dependency between the drying and the milling
processes on one and the NIR-signal on the other side. As a result,
different characteristic parameters have been defined. A short
overview of the Celitement process and the challenging tasks of the
online measurement and evaluation of the product quality will be
presented. Subsequently, methods for systematic development of
near-infrared calibration models and the determination of the final
calibration model will be introduced. The application of the model on
experimental data illustrates that NIR-spectroscopy allows for a quick
and sufficiently exact determination of crucial process parameters.
Abstract: In this study, the effects and interactions of reaction
time and capping agent assistance during sol-gel synthesis of
magnesium substituted hydroxyapatite nanopowder (MgHA) on
hydroxyapatite (HA) to β-tricalcium phosphate (β-TCP) ratio, Ca/P
ratio and mean crystallite size was examined experimentally as well
as through statistical analysis. MgHA nanopowders were synthesized
by sol-gel technique at room temperature using aqueous solution of
calcium nitrate tetrahydrate, magnesium nitrate hexahydrate and
potassium dihydrogen phosphate as starting materials. The reaction
time for sol-gel synthesis was varied between 15 to 60 minutes. Two
process routes were followed with and without addition of
triethanolamine (TEA) in the solutions. The elemental compositions
of as-synthesized powders were determined using X-ray fluorescence
(XRF) spectroscopy. The functional groups present in the assynthesized
MgHA nanopowders were established through Fourier
Transform Infrared Spectroscopy (FTIR). The amounts of phases
present, Ca/P ratio and mean crystallite sizes of MgHA nanopowders
were determined using X-ray diffraction (XRD). The HA content in
biphasic mixture of HA and β-TCP and Ca/P ratio in as-synthesized
MgHA nanopowders increased effectively with reaction time of sols
(p0.15, two way ANOVA). The MgHA nanopowders
synthesized with TEA assistance exhibited 14 nm lower crystallite
size (p
Abstract: We used live E. coli containing synthetic genetic
oscillators to study how the degree of synchrony between the genetic
circuits of sister cells changes with temperature. We found that both
the mean and the variability of the degree of synchrony between the
fluorescence signals from sister cells are affected by temperature.
Also, while most pairs of sister cells were found to be highly
synchronous in each condition, the number of asynchronous pairs
increased with increasing temperature, which was found to be due to
disruptions in the oscillations. Finally we provide evidence that these
disruptions tend to affect multiple generations as opposed to
individual cells. These findings provide insight in how to design
more robust synthetic circuits and in how cell division can affect their
dynamics.
Abstract: Coal fly ash is formed as a solid waste product from
the combustion of coal in coal fired power stations. Huge amounts of
fly ash are produced globally every year and are predicted to
increase. Nowadays, less than half of the fly ash is used as a raw
material for cement manufacturing, construction and the rest of it is
disposed as a waste causing yet another environmental concern. For
this reason, the recycling of this kind of slurries into useful materials
is quite important in terms of economical and environmental aspects.
The purpose of this study is to evaluate the Orhaneli and
Tuncbilek coal fly ashes for utilization in some industrial
applications. Therefore the mineralogical and chemical compositions
of these fly ashes were analyzed by X-ray fluorescence spectroscopy,
ourier-transform infrared spectrometer, and X-ray diffraction. The
silicon (Si) and aluminum (Al) in the fly ashes were activated by
alkali fusion technique with sodium hydroxide. The obtained extracts
were analyzed for Si and Al content by inductively coupled plasma
optical emission spectrometry.
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 discarded clam shell waste, fossil and edible oil
as biolubricant feedstocks create environmental impacts and food
chain dilemma, thus this work aims to circumvent these issues by
using activated saltwater clam shell waste (SCSW) as solid catalyst
for conversion of Jatropha curcas oil as non-edible sources to ester
biolubricant. The characterization of solid catalyst was done by
Differential Thermal Analysis-Thermo Gravimetric Analysis (DTATGA),
X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD),
Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron
Microscopy (FESEM) and Fourier Transformed Infrared
Spectroscopy (FTIR) analysis. The calcined catalyst was used in the
transesterification of Jatropha oil to methyl ester as the first step, and
the second stage was involved the reaction of Jatropha methyl ester
(JME) with trimethylolpropane (TMP) based on the various process
parameters. The formated biolubricant was analyzed using the
capillary column (DB-5HT) equipped Gas Chromatography (GC).
The conversion results of Jatropha oil to ester biolubricant can be
found nearly 96.66%, and the maximum distribution composition
mainly contains 72.3% of triester (TE).
Abstract: The article presents the results of the application of
artificial neural networks to separate the fluorescent contribution of
nanodiamonds used as biomarkers, adsorbents and carriers of drugs
in biomedicine, from a fluorescent background of own biological
fluorophores. The principal possibility of solving this problem is
shown. Use of neural network architecture let to detect fluorescence
of nanodiamonds against the background autofluorescence of egg
white with high accuracy - better than 3 ug/ml.
Abstract: Fly ash is an important waste, produced in thermal
power plants which causes very important environmental pollutions.
For this reason the usage and evaluation the fly ash in various areas
are very important. Nearly, 15 million tons/year of fly ash is
produced in Turkey. In this study, usage of fly ash with diatomite and
molasses for heavy metal (Cd) adsorption from wastewater is
investigated. The samples of Seyitomer region fly ash were analyzed
by X-ray fluorescence (XRF) and Scanning Electron Microscope
(SEM) then diatomite (0 and 1% in terms of fly ash, w/w) and
molasses (0-0.75 mL) were pelletized under 30 MPa of pressure for
the usage of cadmium (Cd) adsorption in wastewater. After the
adsorption process, samples of Seyitomer were analyzed using
Optical Emission Spectroscopy (ICP-OES). As a result, it is seen that
the usage of Seyitomer fly ash is proper for cadmium (Cd) adsorption
and an optimum adsorption yield with 52% is found at a compound
with Seyitomer fly ash (10 g), diatomite (0.5 g) and molasses (0.75
mL) at 2.5 h of reaction time, pH:4, 20ºC of reaction temperature and
300 rpm of stirring rate.
Abstract: Amyloid aggregation of polypeptides is related to a
growing number of pathologic states known as amyloid disorders. In
recent years, blocking or reversing amyloid aggregation via the use of
small compounds are considered as two useful approaches in
hampering the development of these diseases. In this research, we
have compared the ability of several manganese-salen derivatives, as
synthetic compounds, and apigenin, as a natural flavonoid, to inhibit
of hen egg-white lysozyme (HEWL) aggregation, as an in vitro
model system.
Different spectroscopic analyses such as Thioflavin T (ThT) and
Anilinonaphthalene-8-sulfonic acid (ANS) fluorescence, Congo red
(CR) absorbance along with transmission electron microscopy were
used in this work to monitor the HEWL aggregation kinetic and
inhibition. Our results demonstrated that both type of compounds
were capable to prevent the formation of lysozyme amyloid
aggregation in vitro. In addition, our data indicated that synthetic
compounds had higher activity to inhibit of the β-sheet structures
relative to natural compound. Regarding the higher antioxidant
activities of the salen derivatives, it can be concluded that in addition
to aromatic rings of each of the compounds, the potent antioxidant
properties of salen derivatives contributes to lower lysozyme fibril
accumulation.
Abstract: Two new metal-based anticancer chemotherapeutic
agents, [(Ph2Sn)2(HGuO)2(phen)Cl2] 1 and [(Ph3Sn)(HGuO)(phen)]-
Cl.CH3OH.H2O 2, were designed, prepared and characterized by
analytical and spectral (IR, ESI-Mass, 1H, 13C and 119Sn NMR)
techniques. The proposed geometry of Sn(IV) in 1 and 2 is distorted
octahedral and distorted trigonal-bipyramidal, respectively. Both 1
and 2 exhibit potential cytotoxicity in vitro against MCF-7, HepG-2
and DU-145 cell lines. The intrinsic binding constant (Kb) values of 1
(2.33 × 105 M-1) and 2 (2.46 × 105 M-1) evaluated from UV-Visible
absorption studies suggest non-classical electrostatic mode of
interaction via phosphate backbone of DNA double helix. The Stern-
Volmer quenching constant (Ksv) of 1 (9.74 × 105 M-1) and 2 (2.9 ×
106 M-1) determined by fluorescence studies suggests the groove
binding and intercalation mode for 1 and 2, respectively. Effective
cleavage of pBR322 DNA is induced by 1.Their interaction with
DNA of cancer cells may account for potency.
Abstract: This research presents the design, fabrication and application of a flavor sensor for an integrated electronic tongue and electronic nose that can allow rapid characterization of multi-component mixtures in a solution. The odor gas and liquid are separated using hydrophobic porous membrane in micro fluidic channel. The sensor uses an array composed of microbeads in micromachined cavities localized on silicon wafer. Sensing occurs via colorimetric and fluorescence changes to receptors and indicator molecules that are attached to termination sites on the polymeric microbeads. As a result, the sensor array system enables simultaneous and near-real-time analyses using small samples and reagent volumes with the capacity to incorporate significant redundancies. One of the key parts of the system is a passive pump driven only by capillary force. The hydrophilic surface of the fluidic structure draws the sample into the sensor array without any moving mechanical parts. Since there is no moving mechanical component in the structure, the size of the fluidic structure can be compact and the fabrication becomes simple when compared to the device including active microfluidic components. These factors should make the proposed system inexpensive to mass-produce, portable and compatible with biomedical applications.
Abstract: Construction industry in Greece consumes annually
more than 25 million tons of natural aggregates originating mainly
from quarries. At the same time, more than 2 million tons of
construction and demolition waste are deposited every year, usually
without control, therefore increasing the environmental impact of this
sector. A potential alternative for saving natural resources and
minimize landfilling, could be the recycling and re-use of Concrete
and Demolition Waste (CDW) in concrete production. Moreover, in
order to conform to the European legislation, Greece is obliged to
recycle non-hazardous construction and demolition waste to a
minimum of 70% by 2020. In this paper characterization of recycled
materials - commercially and laboratory produced, coarse and fine,
Recycled Concrete Aggregates (RCA) - has been performed. Namely,
X-Ray Fluorescence and X-ray diffraction (XRD) analysis were used
for chemical and mineralogical analysis respectively. Physical
properties such as particle density, water absorption, sand equivalent
and resistance to fragmentation were also determined. This study,
first time made in Greece, aims at outlining the differences between
RCA and natural aggregates and evaluating their possible influence
in concrete performance. Results indicate that RCA’s chemical
composition is enriched in Si, Al, and alkali oxides compared to
natural aggregates. X-ray diffraction (XRD) analyses results
indicated the presence of calcite, quartz and minor peaks of mica and
feldspars. From all the evaluated physical properties of coarse RCA,
only water absorption and resistance to fragmentation seem to have a
direct influence on the properties of concrete. Low Sand Equivalent
and significantly high water absorption values indicate that fine
fractions of RCA cannot be used for concrete production unless
further processed. Chemical properties of RCA in terms of water
soluble ions are similar to those of natural aggregates. Four different
concrete mixtures were produced and examined, replacing natural
coarse aggregates with RCA by a ratio of 0%, 25%, 50% and 75%
respectively. Results indicate that concrete mixtures containing
recycled concrete aggregates have a minor deterioration of their
properties (3-9% lower compression strength at 28 days) compared to
conventional concrete containing the same cement quantity.
Abstract: Concrete durability as an important engineering property of concrete, determining the service life of concrete structures very significantly, can be threatened and even lost due to the interactions of concrete with external environment. Bio-corrosion process caused by presence and activities of microorganisms producing sulphuric acid is a special type of sulphate deterioration of concrete materials. The effects of sulphur-oxidizing bacteria Acidithiobacillus thiooxidans on various concrete samples, based on silica fume and zeolite, were investigated in laboratory during 180 days. A laboratory study was conducted to compare the performance of concrete samples in terms of the concrete deterioration influenced by the leaching of calcium and silicon compounds from the cement matrix. The changes in the elemental concentrations of calcium and silicon in both solid samples and liquid leachates were measured by using X – ray fluorescence method. Experimental studies confirmed the silica fume based concrete samples were found out to have the best performance in terms of both silicon and calcium ions leaching.