Abstract: In recent years, there have been attempts to store
natural gas in adsorptive form. This is called adsorptive natural gas,
or ANG. The problem with this technology is the low sorption
capacity. The purpose is to achieve compressed natural gas (CNG)
capacity of 230 V/V. Further research is required to achieve such
target. Several research studies have been performed with this target;
through either the modification or development of new sorbents or
the optimization of the operation sorption process itself. In this work,
storage of methane on molecular sieves 5A and 13X was studied on
dry basis, and on wet basis to certain extent. The temperature and the
pressure dynamics were investigated. The results indicated that
regardless of the charge pressure, the time for the peak temperature
during the methane charge process is always the same. This can be
used as a characteristic of the adsorbent. The total achieved
deliveries using molecular sieves were much lower than that of
activated carbons; 53.0 V/V for the case of 13X molecular sieves and
43 V/V for the case of 5A molecular sieves, both at 2oC and 4 MPa
(580 psi). Investigation of charge pressure dynamic using wet
molecular sieves at 2oC and a mass ratio of 0.5, revealed slowness of
the process and unexpected behavior.
Abstract: Studying alternative raw materials for biodiesel production is of major importance. The use of mixtures with incorporation of wastes is an environmental friendly alternative and might reduce biodiesel production costs. The objective of the present work was: (i) to study biodiesel production using waste frying oil mixed with pork lard and (ii) to understand how mixture composition influences biodiesel quality. Biodiesel was produced by transesterification and quality was evaluated through determination of several parameters according to EN 14214. The weight fraction of lard in the mixture varied from 0 to 1 in 0.2 intervals. Biodiesel production yields varied from 81.7 to 88.0 (wt%), the lowest yields being the ones obtained using waste frying oil and lard alone as raw materials. The obtained products fulfilled most of the determined quality specifications according to European biodiesel quality standard EN 14214. Minimum purity (96.5 wt%) was closely obtained when waste frying oil was used alone and when 0.2% of lard was incorporated in the raw material (96.3 wt%); however, it ranged from 93.9 to 96.3 (wt%) being always close to the limit. From the evaluation of the influence of mixture composition in biodiesel quality, it was possible to establish a model to be used for predicting some parameters of biodiesel resulting from mixtures of waste frying oil with lard when different lard contents are used.
Abstract: Fecal sterol has been proposed as a chemical indicator
of human fecal pollution even when fecal coliform populations have
diminished due to water chlorination or toxic effects of industrial
effluents. This paper describes an improved derivatization procedure
for simultaneous determination of four fecal sterols including
coprostanol, epicholestanol, cholesterol and cholestanol using gas
chromatography-mass spectrometry (GC-MS), via optimization study
on silylation procedures using N-O-bis
(trimethylsilyl)-trifluoroacetamide (BSTFA), and
N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide
(MTBSTFA), which lead to the formation of trimethylsilyl (TMS) and
tert-butyldimethylsilyl (TBS) derivatives, respectively. Two
derivatization processes of injection-port derivatization and water bath
derivatization (60 oC, 1h) were inspected and compared. Furthermore,
the methylation procedure at 25 oC for 2h with
trimethylsilydiazomethane (TMSD) for fecal sterols analysis was also
studied. It was found that most of TMS derivatives demonstrated the
highest sensitivities, followed by methylated derivatives. For BSTFA
or MTBSTFA derivatization processes, the simple injection-port
derivatization process could achieve the same efficiency as that in the
tedious water bath derivatization procedure.
Abstract: The selective recovery of heavy metals of Cu, Zn, Ni and Cr from a mixed plating sludge by sulfidation and oxidation treatment was targeted in this study. At first, the mixed plating sludge was simultaneously subjected to an extraction and Cu sulfidation process at pH=1.5 to dissolve heavy metals and to precipitate Cu2+ as CuS. In the next step, the sulfidation treatment of Zn was carried out at pH=4.5 and the residual solution was subjected to an oxidation treatment of chromium with H2O2 at pH=10.0. After the experiments, the selectivity of metal precipitation and the chromium oxidation ratio were evaluated. As results, it was found that the filter cake obtained after selective sulfidation of Cu was composed of 96.6% of Cu (100% equals to the sum of Cu, Zn, Ni and Cr contents). Such findings confirmed that almost complete extraction of heavy metals was achieved at pH=1.5 and also that Cu could be selectively recovered as CuS. Further, the filter cake obtained at pH=4.5 was composed of 91.5% Zn and 6.83% of Cr. Regarding the chromium oxidation step, the chromium oxidation ratio was found to increase with temperature and the addition of oxidation agent of H2O2, but only oxidation ratio of 59% was achieved at a temperature of 60°C and H2O2 to Cr3+ equivalent ratio of 180.
Abstract: Understanding the cell's large-scale organization is an
interesting task in computational biology. Thus, protein-protein
interactions can reveal important organization and function of the
cell. Here, we investigated the correspondence between protein
interactions and function for the yeast. We obtained the correlations
among the set of proteins. Then these correlations are clustered using
both the hierarchical and biclustering methods. The detailed analyses
of proteins in each cluster were carried out by making use of their
functional annotations. As a result, we found that some functional
classes appear together in almost all biclusters. On the other hand, in
hierarchical clustering, the dominancy of one functional class is
observed. In brief, from interaction data to function, some correlated
results are noticed about the relationship between interaction and
function which might give clues about the organization of the
proteins.
Abstract: Films of pure tin oxide SnO2 and in presence of
antimony atoms (SnO2-Sb) deposited onto glass substrates have
shown a sufficiently high energy gap to be transparent in the visible
region, a high electrical mobility and a carrier concentration which
displays a good electrical conductivity [1]. In this work, the effects of
polycrystalline silicon substrate on the optical properties of pure and
Sb doped tin oxide is investigated.
We used the APCVD (atmospheric pressure chemical vapour
deposition) technique, which is a low-cost and simple technique,
under nitrogen ambient, for growing this material. A series of SnO2
and SnO2-Sb have been deposited onto polycrystalline silicon
substrates with different contents of antimony atoms at the same
conditions of deposition (substrate temperature, flow oxygen,
duration and nitrogen atmosphere of the reactor). The effect of the
substrate in terms of morphology and nonlinear optical properties,
mainly the reflectance, was studied. The reflectance intensity of the
device, compared to the reflectance of tin oxide films deposited
directly on glass substrate, is clearly reduced on the overall
wavelength range. It is obvious that the roughness of the poly-c
silicon plays an important role by improving the reflectance and
hence the optical parameters.
A clear shift in the minimum of the reflectance upon doping level
is observed. This minimum corresponds to strong free carrier
absorption, resulting in different plasma frequency. This effect is
followed by an increase in the reflectance depending of the antimony
doping. Applying the extended Drude theory to the combining
optical and electrical obtained results these effects are discussed.
Abstract: The present work is concerned with sulfidation of Cu,
Zn and Ni containing plating wastewater with CaS. The sulfidation
experiments were carried out at a room temperature by adding solid
CaS to simulated metal solution containing either single-metal of Ni,
Zn and Cu, or Ni-Zn-Cu mixture. At first, the experiments were
conducted without pH adjustment and it was found that the complete
sulfidation of Zn and Ni was achieved at an equimolar ratio of CaS to a
particular metal. However, in the case of Cu, a complete copper
sulfidation was achieved at CaS to Cu molar ratio of about 2. In the
case of the selective sulfidation, a simulated plating solution
containing Cu, Zn and Ni at the concentration of 100 mg/dm3 was
treated with CaS under various pH conditions. As a result, selective
precipitation of metal sulfides was achieved by a sulfidation treatment
at different pH values. Further, the precipitation agents of NaOH,
Na2S and CaS were compared in terms of the average specific
filtration resistance and compressibility coefficients of metal sulfide
slurry. Consequently, based on the lowest filtration parameters of the
produced metal sulfides, it was concluded that CaS was the most
effective precipitation agent for separation and recovery of Cu, Zn and
Ni.
Abstract: In this paper the combination of thermal oxidation and
electrochemical anodizing processes is used to produce titanium
oxide layers. The response of titanium alloy Ti6Al4V to oxidation
processes at various temperatures and electrochemical anodizing in
various voltages are investigated. Scanning electron microscopy
(SEM); X-Ray Diffraction (XRD) and porosity determination have
been used to characterize the oxide layer thickness, surface
morphology, oxide layer-substrate adhesion and porosity. In the first
experiment, samples modified by thermal oxidation process then
followed by electrochemical anodizing. Second experiment consists
of surfaces modified by electrochemical anodizing process and then
followed by thermal oxidation. The first method shows better
properties than other one. In second experiment, Surfaces modified
were achieved by thicker and more adherent thick oxide layers on
titanium surface. The existence of an electrochemical anodized oxide
layer did not improve the adhesion of thermal oxide layer. The high
temperature, thermal formation of an oxide layer leads to a coarse
oxide grain morphology and a complete oxidative particle. In
addition, in high temperature oxidation porosity content is increased.
The oxide layer of thermal oxidation and electrochemical anodizing
processes; on Ti–6Al–4V substrate was covered with different
colored oxide layers.
Abstract: Palladium-catalyzed hydrodechlorination is a
promising alternative for the treatment of environmentally relevant
water bodies, such as groundwater, contaminated with chlorinated
organic compounds (COCs). In the aqueous phase
hydrodechlorination of COCs, Pd-based catalysts were found to have
a very high catalytic activity. However, the full utilization of the
catalyst-s potential is impeded by the sensitivity of the catalyst to
poisoning and deactivation induced by reduced sulfur compounds
(e.g. sulfides). Several regenerants have been tested before to recover
the performance of sulfide-fouled Pd catalyst. But these only
delivered partial success with respect to re-establishment of the
catalyst activity. In this study, the deactivation behaviour of
Pd/Al2O3 in the presence of sulfide was investigated. Subsequent to
total deactivation the catalyst was regenerated in the aqueous phase
using potassium permanganate. Under neutral pH condition,
oxidative regeneration with permanganate delivered a slow recovery
of catalyst activity. However, changing the pH of the bulk solution to
acidic resulted in the complete recovery of catalyst activity within a
regeneration time of about half an hour. These findings suggest the
superiority of permanganate as regenerant in re-activating Pd/Al2O3
by oxidizing Pd-bound sulfide.
Abstract: Air pollution is a major environmental health
problem, affecting developed and developing countries around the
world. Increasing amounts of potentially harmful gases and
particulate matter are being emitted into the atmosphere on a global
scale, resulting in damage to human health and the environment.
Petroleum-related air pollutants can have a wide variety of adverse
environmental impacts. In the crude oil production sectors, there is a
strong need for a thorough knowledge of gaseous emissions resulting
from the flaring of associated gas of known composition on daily
basis through combustion activities under several operating
conditions. This can help in the control of gaseous emission from
flares and thus in the protection of their immediate and distant
surrounding against environmental degradation.
The impacts of methane and non-methane hydrocarbons emissions
from flaring activities at oil production facilities at Kuwait Oilfields
have been assessed through a screening study using records of flaring
operations taken at the gas and oil production sites, and by analyzing
available meteorological and air quality data measured at stations
located near anthropogenic sources. In the present study the
Industrial Source Complex (ISCST3) Dispersion Model is used to
calculate the ground level concentrations of methane and nonmethane
hydrocarbons emitted due to flaring in all over Kuwait
Oilfields.
The simulation of real hourly air quality in and around oil
production facilities in the State of Kuwait for the year 2006,
inserting the respective source emission data into the ISCST3
software indicates that the levels of non-methane hydrocarbons from
the flaring activities exceed the allowable ambient air standard set by
Kuwait EPA. So, there is a strong need to address this acute problem
to minimize the impact of methane and non-methane hydrocarbons
released from flaring activities over the urban area of Kuwait.
Abstract: This study deals with evaluation of influence of salinity (NaCl) onto equilibrium of Cu and Ni removal from aqueous solutions by natural sorbent – zeolite. Equilibrium data were obtained by batch experiments. The salinity of the aqueous solution was influenced by dissolving NaCl in distilled water. It was studied in the range of NaCl concentrations from 1 g.l-1 to 100g.l-1. For Cu sorption there is a significant influence of salinity. The maximum capacity of zeolite for Cu was decreasing with growing concentration of NaCl. For Ni sorption there is not so significant influence of salinity as for Cu. The maximum capacity of zeolite for Ni was slightly decreasing with growing concentration of NaCl.
Abstract: The present models and simulation algorithms of intracellular stochastic kinetics are usually based on the premise that diffusion is so fast that the concentrations of all the involved species are homogeneous in space. However, recents experimental measurements of intracellular diffusion constants indicate that the assumption of a homogeneous well-stirred cytosol is not necessarily valid even for small prokaryotic cells. In this work a mathematical treatment of diffusion that can be incorporated in a stochastic algorithm simulating the dynamics of a reaction-diffusion system is presented. The movement of a molecule A from a region i to a region j of the space is represented as a first order reaction Ai k- ! Aj , where the rate constant k depends on the diffusion coefficient. The diffusion coefficients are modeled as function of the local concentration of the solutes, their intrinsic viscosities, their frictional coefficients and the temperature of the system. The stochastic time evolution of the system is given by the occurrence of diffusion events and chemical reaction events. At each time step an event (reaction or diffusion) is selected from a probability distribution of waiting times determined by the intrinsic reaction kinetics and diffusion dynamics. To demonstrate the method the simulation results of the reaction-diffusion system of chaperoneassisted protein folding in cytoplasm are shown.