Abstract: Effect of high temperature exposure on properties of cement mortar containing municipal solid waste incineration (MSWI) bottom ash as partial natural aggregate replacement is analyzed in the paper. The measurements of mechanical properties, bulk density, matrix density, total open porosity, sorption and desorption isotherms are done on samples exposed to the temperatures of 20°C to 1000°C. TGA analysis is performed as well. Finally, the studied samples are analyzed by IR spectroscopy in order to evaluate TGA data.
Abstract: Borate minerals have attracted considerable attention in the past years due to their structural chemistry and mechanical properties in several industries. Recently, increasing attention has been paid to the use of; synthetically produced magnesium borates as catalysts reinforcing material for plastics, the conversion of hydrocarbons, electro-conductive treating agent, anti-wear and anti-corrosion materials. Magnesium borates can be synthesized by several methods such as; hydrothermal and solid-state (thermal) processes. In this study the hydrothermal production method was applied at the modest temperature of 80C along with convenient crystal growth. Using MgCl2.6H2O, H3BO3, and NaOH as starting materials, 30, 60, 120, 240 minutes of reaction times were studied. After all, the crystal structure and the morphology of the products were examined by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). As a result the forms of Admontite and Mcallisterite minerals were synthesized.
Abstract: Zinc borates can be used as multi-functional
synergistic additives with flame retardant additives in polymers. Zinc
borate is white, non-hygroscopic and powder type product. The most
important properties are low solubility in water and high dehydration
temperature. Zinc borates dehydrate above 290°C and anhydrous zinc
borate has thermal resistance about 400°C. Zinc borates can be
synthesized using several methods such as hydrothermal and solidstate
processes. In this study, the solid-state method was applied at
low temperatures of 600oC and 700oC using the starting materials of
ZnO and H3BO3 with several mole ratios. The reaction time was
determined as 4 hours after some preliminary experiments. After the
synthesis, the crystal structure and the morphology of the products
were examined by X-Ray Diffraction (XRD) and Fourier Transform
Infrared Spectroscopy (FT-IR). As a result the forms of ZnB4O7,
Zn3(BO3)2, ZnB2O4 were synthesized and obtained along with the
unreacted ZnO.
Abstract: Utilization of bagasse ash for silica sources is one of
the most common application for agricultural wastes and valuable
biomass byproducts in sugar milling. The high percentage silica
content from bagasse ash was used as silica source for sodium
silicate solution. Different heating temperature, time and acid
treatment were studies for silica extraction. The silica was
characterized using various techniques including X-ray fluorescence,
X-ray diffraction, Scanning electron microscopy, and Fourier
Transform Infrared Spectroscopy method,. The synthesis conditions
were optimized to obtain the bagasse ash with the maximum silica
content. The silica content of 91.57 percent was achieved from
heating of bagasse ash at 600°C for 3 hours under oxygen feeding
and HCl treatment. The result can be used as value added for bagasse
ash utilization and minimize the environmental impact of disposal
problems.
Abstract: The complex structure of lignocellulose leads to great
difficulties in converting it to fermentable sugars for the ethanol
production. The major hydrolysis impediments are the crystallinity of
cellulose and the lignin content. To improve the efficiency of
enzymatic hydrolysis, microbial pretreatment of corncob was
investigated using two bacterial strains of Bacillus subtilis A 002 and
Cellulomonas sp. TISTR 784 (expected to break open the crystalline
part of cellulose) and lignin-degrading fungus, Phanerochaete
sordida SK7 (expected to remove lignin from lignocellulose). The
microbial pretreatment was carried out with each strain under its
optimum conditions. The pretreated corncob samples were further
hydrolyzed to produce reducing glucose with low amounts of
commercial cellulase (25 U·g-1 corncob) from Aspergillus niger. The
corncob samples were determined for composition change by X-ray
diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
and scanning electron microscope (SEM). According to the results,
the microbial pretreatment with fungus, P. sordida SK7 was the most
effective for enhancing enzymatic hydrolysis, approximately, 40%
improvement.
Abstract: The hybrid membranes containing inorganic materials in polymer matrix are identified as a remarkable family of proton conducting hybrid electrolytes. In this work, the proton conducting inorganic/organic hybrid membranes for proton exchange membrane fuel cells (PEMFCs) were prepared using polyvinyl alcohol (PVA), tetraethoxyorthosilane (TEOS) and heteropolyacid (HPA). The synthesized hybrid membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), Scanning electron microscopy (SEM) and Thermogravimetry analysis (TGA). The effects of heteropolyacid incorporation on membrane properties, including morphology and thermal stability were extensively investigated.
Abstract: Low silica type X (LSX) Zeolite is one of useful
material in many manufacturing due to the advantage properties
including high surface area, stability, microporous crystalline
aluminosilicates and positive ion in an extra–framework. The LSX
was used rice husk silica source which obtained by leaching with
hydrochloric acid and calcination at 500 C. To improve the
synthesis method, the LSX was crystallizated in Teflon–lined
autoclave will expedite deceasing of the amorphous particles. The
mixed gel with composition of 5.5 Na2O : 1.65 K2O : Al2O3 : 2.2
SiO2 : 122 H2O was crystallized in different container
(Polypropylene bottom and Teflon–lined autoclave). The obtained
powder was characterized by X–ray diffraction (XRD), X–ray
fluorescence spectrometry, N2 adsorption-desorption analysis BET
surface area Scanning electron microscopy (SEM) and Fourier
transform infrared spectroscopy to justify the quality of zeolite. The
results showed the crystallized zeolite in Teflon lined autoclave has
102.8 nm of crystal size, 286 m2/g of surface area and fewer amounts
of round amorphous particles when compared with the crystallized
zeolite in Polypropylene.
Abstract: Density functional theory (DFT) calculations were
performed to compute nitrogen-14 and boron-11 nuclear quadrupole
resonance (NQR) spectroscopy parameters in the representative
model of armchair boron nitride nanotube (BNNT) for the first time.
The considered model consisting of 1 nm length of H-capped (5, 5)
single-wall BNNT were first allowed to fully relax and then the NQR
calculations were carried out on the geometrically optimized model.
The evaluated nuclear quadrupole coupling constants and asymmetry
parameters for the mentioned nuclei reveal that the model can be
divided into seven layers of nuclei with an equivalent electrostatic
environment where those nuclei at the ends of tubes have a very
strong electrostatic environment compared to the other nuclei along
the length of tubes. The calculations were performed via Gaussian 98
package of program.
Abstract: In this study, multiwall carbon nanotubes (MWNTs)
were modified with nitric acid chemically and by dielectric barrier
discharge (DBD) plasma in an oxygen-based atmosphere. Used
carbon nanotubes (CNTs) were prepared by chemical vapour
deposition (CVD) floating catalyst method. For removing amorphous
carbon and metal catalyst, MWNTs were exposed to dry air and
washed with hydrochloric acid. Heating purified CNTs under helium
atmosphere caused elimination of acidic functional groups. Fourier
transformed infrared spectroscopy (FTIR) shows formation of
oxygen containing groups such as C=O and COOH. Brunauer,
Emmett, Teller (BET) analysis revealed that functionalization causes
generation of defects on the sidewalls and opening of the ends of
CNTs. Results of temperature-programmed desorption (TPD) and gas
chromatography(GC) indicate that nitric acid treatment create more
acidic groups than plasma treatment.
Abstract: Nanocrystals (NC) alloyed composite CdSxSe1-x(x=0
to 1) have been prepared using the chemical solution deposition
technique. The energy band gap of these alloyed nanocrystals of
approximately the same size, have been determined by scanning
tunneling spectroscopy (STS) technique at room temperature. The
values of the energy band gap obtained directly using STS are
compared to those measured by optical spectroscopy. Increasing the
molar fraction ratio x from 0 to 1 causes clearly observed increase in
the band gap of the alloyed composite nanocrystal. Vegard-s law was
applied to calculate the parameters of the effective mass
approximation (EMA) model and the dimension obtained were
compared to the values measured by STM. The good agreement of
the calculated and measured values is a direct result of applying
Vegard's law in the nanocomposites.
Abstract: Residual dye contents in textile dyeing wastewater have complex aromatic structures that are resistant to degrade in biological wastewater treatment. The objectives of this study were to determine the effectiveness of nanoscale zerovalent iron (NZVI) to decolorize Reactive Black 5 (RB5) and Reactive Red 198 (RR198) in synthesized wastewater and to investigate the effects of the iron particle size, iron dosage and solution pHs on the destruction of RB5 and RR198. Synthesized NZVI was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The removal kinetic rates (kobs) of RB5 (0.0109 min-1) and RR198 (0.0111 min-1) by 0.5% NZVI were many times higher than those of microscale zerovalent iron (ZVI) (0.0007 min-1 and 0.0008 min-1, respectively). The iron dosage increment exponentially increased the removal efficiencies of both RB5 and RR198. Additionally, lowering pH from 9 to 5 increased the decolorization kinetic rates of both RB5 and RR198 by NZVI. The destruction of azo bond (N=N) in the chromophore of both reactive dyes led to decolorization of dye solutions.
Abstract: In this study, we report the synthesis and
characterization of nanohydroxyapatite (nHAp) in gelatin-starch
matrix via biomimetic method. Characterization of the samples was
performed using X-ray diffraction (XRD) and Fourier Transform
infrared spectroscopy (FT-IR). The Size and morphology of the
nHAp samples were determined using scanning and transmission
electron microscopy (SEM and TEM). The results reveal that the
shape and morphology of nHAp is influenced by presence of
biopolymers as template. Carbonyl and amino groups from gelatin
and hydroxyl from starch play crucial roles in HAp formation on the
surface of gelatin-starch.
Abstract: Polarization modulation infrared reflection absorption
spectroscopy (PM-IRRAS) in combination with electrochemistry,
was employed to study the influence of surface charge (potential) on
the kinetics of bovine serum albumin (BSA) adsorption on a
biomedical-grade 316LVM stainless steel surface is discussed. The
BSA adsorption kinetics was found to greatly depend on the surface
potential. With an increase in surface potential towards more
negative values, both the BSA initial adsorption rate and the
equilibrium (saturated) surface concentration also increased. Both
effects were explained on the basis of replacement of well-ordered
water molecules at the 316LVM / solution interface, i.e. by the
increase in entropy of the system.
Abstract: Martensitic stainless steels have been extensively used for their good corrosion resistance and better mechanical properties. Heat treatment was suggested as one of the most excellent ways to this regard; hence, it affects the microstructure, mechanical and corrosion properties of the steel. In the current research work the microstructural changes and corrosion behavior in an AISI 420A stainless steel exposed to temperatures in the 980-1035oC range were investigated. The heat treatment is carried out in vacuum furnace within the said temperature range. The quenching of the samples was carried out in oil, brine and water media. The formation and stability of passive film was studied by Open Circuit Potential, Potentiodynamic polarization and Electrochemical Scratch Tests. The Electrochemical Impedance Spectroscopy results simulated with Equivalent Electrical Circuit suggested bilayer structure of outer porous and inner barrier oxide films. The quantitative data showed thick inner barrier oxide film retarded electrochemical reactions. Micrographs of the quenched samples showed sigma and chromium carbide phases which prove the corrosion resistance of steel alloy.
Abstract: The hydrolysis kinetics of polycrystalline lithium hydride (LiH) in argon at various low humidities was measured by gravimetry and Raman spectroscopy with ambient water concentration ranging from 200 to 1200 ppm. The results showed that LiH hydrolysis curve revealed a paralinear shape, which was attributed to two different reaction stages that forming different products as explained by the 'Layer Diffusion Control' model. Based on the model, a novel two-stage rate equation for LiH hydrolysis reactions was developed and used to fit the experimental data for determination of Li2O steady thickness Hs and the ultimate hydrolysis rate vs. The fitted data presented a rise of Hs as ambient water concentration cw increased. However, in spite of the negative effect imposed by Hs increasing, the upward trend of vs remained, which implied that water concentration, rather than Li2O thickness, played a predominant role in LiH hydrolysis kinetics. In addition, the proportional relationship between vsHs and cw predicted by rate equation and confirmed by gravimetric data validated the model in such conditions.
Abstract: Ultrathin (UTD) and Nanoscale (NSD) SOI-MOSFET devices, sharing a similar W/L but with a channel thickness of 46nm and 1.6nm respectively, were fabricated using a selective “gate recessed” process on the same silicon wafer. The electrical transport characterization at room temperature has shown a large difference between the two kinds of devices and has been interpreted in terms of a huge unexpected series resistance. Electrical characteristics of the Nanoscale device, taken in the linear region, can be analytically derived from the ultrathin device ones. A comparison of the structure and composition of the layers, using advanced techniques such as Focused Ion Beam (FIB) and High Resolution TEM (HRTEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), contributes an explanation as to the difference of transport between the devices.
Abstract: This current research focused on development of degradable starch based packaging film with enhanced mechanical properties. A series of low density polyethylene (LDPE)/tapioca starch compounds with various tapioca starch contents were prepared by twin screw extrusion with the addition of maleic anhydride grafted polyethylene as compatibilizer. Palm cooking oil was used as processing aid to ease the blown film process, thus, degradable film can be processed via conventional blown film machine. Studies on their characteristics, mechanical properties and biodegradation were carried out by Fourier Transform Infrared (FTIR) spectroscopy and optical properties, tensile test and exposure to fungi environment respectively. The presence of high starch contents had an adverse effect on the tensile properties of LDPE/tapioca starch blends. However, the addition of compatibilizer to the blends improved the interfacial adhesion between the two materials, hence, improved the tensile properties of the films. High content of starch amount also was found to increase the rate of biodegradability of LDPE/tapioca starch films. It can be proved by exposure of the film to fungi environment. A growth of microbes colony can be seen on the surface of LDPE/tapioca starch film indicates that the granular starch present on the surface of the polymer film is attacked by microorganisms, until most of it is assimilated as a carbon source.
Abstract: Five lignin samples were fractionated with
Acetone/Water mixtures and the obtained fractions were subjected to
extensive structural characterization, including Fourier Transform
Infrared (FT-IR), Gel permeation Chromatography (GPC) and
Phosphorus-31 NMR spectroscopy (31P-NMR). The results showed
that for all studied lignins the solubility increases with the increment
of the acetone concentration. Wheat straw lignin has the highest
solubility in 90/10 (v/v) Acetone/Water mixture, 400 mg lignin being
dissolved in 1 mL mixture. The weight average molecular weight of
the obtained fractions increased with the increment of acetone
concentration and thus with solubility. 31P-NMR analysis based on
lignin modification by reactive phospholane into phosphitylated
compounds was used to differentiate and quantify the different types
of OH groups (aromatic, aliphatic, and carboxylic) found in the
fractions obtained with 70/30 (v/v) Acetone/Water mixture.
Abstract: A new and novel approach in medicine is the use of
cold plasma for various applications such as sterilization blood
coagulation and cancer cell treatment. In this paper a pin-to-hole
plasma jet suitable for biological applications is investigated and
characterized and the possibility and feasibility of cancer cell
treatment is evaluated. The characterization includes power
consumption via Lissajous method, thermal behavior of plasma using
Infra-red camera as a novel method, Optical Emission Spectroscopy
(OES) to determine the species that are generated. Treatment of
leukemia cancer cells is also implemented and MTT assay is used to
evaluate viability.
Abstract: The gamma radiation in samples of a variety of
natural tiling rocks (granites) produced and imported in Iran use in
the building industry was measured, employing high-resolution
Gamma-ray spectroscopy. The rock samples were pulverized, sealed
in 0.5 liter plastic Marinelli beakers, and measured in the laboratory
with an accumulating time between 50000 and 80000 second each.
From the measured Gamma-ray spectra, activity concentrations were
determined for 232Th (range from 6.5 to 172.2 Bq kg-1), 238U (from
7.5 to 178.1 Bq kg-1 ),226Ra( from 3.8 to 94.2 Bq kg-1 ) 40K (from
556.9 to 1539.2 Bq kg-1). From the 29 samples measured in this
study, “Nehbndan ( Berjand )" appears to present the highest
concentrations for 232Th,“Big Red Flower (China) "for 238U , “
Khoram dareh" for 226 Ra and “ Peranshahr" for 40K , respectively.