Second Palestinian International Conference on Material Science and Nanotechnology (PICNM2016)

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Analysis of Palestinian Olive Oil of Different Storage Ages by Fluorescence Spectroscopy Technique
(2016-03-23) Abu Snouber, J.
This work focuses on the effect of storage age of Palestinian olive oil on the emission and absorption wavelengths using the fluorescence spectroscopy technique. In addition, the effect of storage age of olive oil on the physical properties: viscosity, refractive index, acidity, and mass density are investigated. The olive oil sample which has different storage ages (3, 5, 16 and 17 years) has maximum emitted wavelengths ranged from 348.0 nm – 349.0 nm, 441.5 nm – 465.5 nm and 647.5 nm – 677.5 nm. The emission bands ranged from 328.5 nm – 357.0 nm, 357.0 nm – 633.0 nm and 633.0 nm – 754.5 nm. The viscosity for the sample of 3 years storage age at 25oC is 58.1 cP. The value of the refractive index, the acidity (FFA%) and the mass density are 1.4671, 2.32 and 0.90948 gm/cm3. Some of vitamin E components (α-, β-, δ- and γ-tocopherol), and some of phenolic compounds (gallic acid, p-coumaric acid, o-coumaric, cinnamic acid, tyrosol and caffeic acid) in stored olive oil for more than 3 years showed an increase as the storage age increases. Some of vitamin E components (α-, β-, δ- and γ-tocotrienol), and some of phenolic compounds (vanillic acid and syringic acid) and chlorophyll a and b, pheophytin a and b in stored olive oil for more than 3 years showed a decrease as the storage age increases. The viscosity, refractive index and mass density of olive oil samples at different storage ages decreases as the storage age increases, whereas the acidity increases as the storage age increases. The measured viscosity, refractive index, acidity and mass density of olive oil samples of storage age more than 5 years do not agree with the standard values. The recommended olive oil of storage age less than 5 years is considered as an edible olive oil.
Application of Nanotechnology in Cancer Therapy: A General Overview
(2016-03-23) Assali, M.
Cancer has increased in the last years, and is becoming a major public health problem in Palestine and many other parts in the world. According to the WHO, Cancer is a leading cause of death worldwide, accounting for 8.2 million deaths in 2012 and it is important to mention that tens of million dollars is spent annually on the treatment of cancer cases locally and abroad. However, drug toxicity and tumor resistance of the traditional chemotherapy are two of the main challenges associated with the traditional anticancer drugs. Toxicity can cause fatal consequences such as heart or bone marrow toxicity that lead to the cessation of the treatment. Moreover, the development of drug resistance by tumors in a lot of cases causes the failure of the treatment. Therefore, there is a huge demand to develop a new strategy to fight this lethal disease. One of the promising approaches is the targeted nano-medicine to fight cancer. Nanomedicine has shown obvious benefits in comparison to the traditional chemotherapy such as increasing the targeting efficacy, enhancing permeability and retention, improving the half-lives and consequently decreasing the side effects. Therefore, in this overview different aspects will be discussed: 1. An overview of solid tumors and their characteristics. 2. The drawbacks of conventional chemotherapy. 3. The huge advantages of nanomedicine in fighting cancer in comparison to traditional cancer treatment. 4. The new approaches in drug and gene deliveries and their benefits in cancer therapy. 5. Challenges and opportunities.
Application of Packed-Bed Emulsification System for preparation of Polymer Microcapsules and Double Emulsion
(2016-03-23) Sawalha, Hassan
Polymer microcapsules and double emulsions (emulsion in an emulsion) are widely applied as micro drugs vehicles for controlled release of drugs and bioactive compounds in the body. Several emulsification techniques can be used for preparation of microcapsules and emulsions including high pressure homogenizers, sonication and membrane emulsification.In the present study, the microcapsules and double emulsions are prepared using relatively new premix emulsification method that consists of a packed bed column loaded with glass beads of different sizes (30-90 µm) at various bed heights (2-20 mm). The emulsification procedure starts with preparing a coarse and polydisperse premix emulsion that is then pressurized through the porous media of the packed bed several times. The passage of the large droplets through the pores breaks them up into smaller and more uniform droplets. The transmembrane fluxes recorded with this technique (100-1000 m3/m2•h) were much higher than other membrane emulsification techniques.The size of the microcapsules were 2-10 times smaller than the interstitial voids of the bedswith an average microcapsules size of about 2-8 µm with an average span of ~1. Besides, the effect of the transmembrane pressure, bead size and bed height on the size and span of the microcapsules and droplets was investigated. The results showed that the size of the microcapsules and droplets decreases with increasing the bed height and bead size.
Aqua bromo-bis-(propane-1,3-diamine)copper(II) bromide nanocrystal complex
(2016-03-23) Abd Al-Ghani, Bahaa
Nanocrystal Cu(II) complex was prepared as in the scheme, characterized by spectroscopic techniques (IR, TOF-MS, UV-Visible, TG/DTA) and finally its three dimensional structure was confirmed by X-ray diffraction studies. The CuPIIP ion is five coordinated by four nitrogen atoms of the base ligand and one bromide ion. In the crystal structure, molecules are connected through intermolecular hydrogen bonds of the type N---H...Br and N---H…O.
Au/InSe interface designed as resonators for optical communications
(2016-03-23) Ikmail, Alaa A.
In the current work a 200 nm Gold is used as substrate to 200 nm thick InSe thin film. Both layers are prepared by the physical vapor deposition technique. The optical transmittance, reflectance, and absorbance of the glass/InSe the Au and the Au/InSe films are measured and analyzed in the incident light wavelength range of 300-1100 nm. From these optical spectra the effects of the Au layer on the energy band gap and on the dielectric spectra are determined. Particularly, it was observed that the energy band gap of the InSe films diminish from (1.50/2.76 ) to (1.00 /1.80) eV upon Au layer interfacing leading to a band offset of (0.50/0.96) eV. The real and imaginary parts of the dielectric constant of Au/InSe thin film exhibit resonance at 361 THz. The value corresponds to an energy of 1.50 eV which indicate that the dielectric resonance happens as a result of the direct allowed electronic transitions from the valence to the conduction bands that create the energy band gap of InSe. Such behavior are of interest as it indicate that the corresponding 834 nm wavelength become a standing wave traveling between the valence and conduction band edges. This wavelength value is very close to the 850 nm which is used for optical encoding of communication signals in fiber optics.
Biodegradable Poly (dl-lactide-co-glycolide) Microcapsules as a Drug Delivery System
(2016-03-23) Abu Ain, Younis
Poly dl-lactide co-glycolide (PLG) is a biodegradable polymer that has a slow degradation rate and high permeability to small drug molecules. PLG microcapsules were prepared by emulsifying a polymer solution that consists of PLG/solvent (dichloromethane) into a continuous phase that consists of a nonsolvent solution (water and SDS as a surfactant). After emulsification, the solvent diffuses out of polymer droplets (liquid microcapsules) to the nonsolvent solution and then evaporates at the surface of the nonsolvent to the air. The encapsulation of the limonene within the polymer microcapsules was prepared, and limonene release was determined with time from polymer microcapsules prepared. The PLG microcapsules were prepared using different concentrations of SDS solution, methanol, and ethanol and study of its impact on the size of the PLG microcapsules. Our results show that as the concentration of nonsolvent increases in the process of preparing of PLG microcapsules the size of prepared microcapsules decreases and the limonene release increases from polymer microcapsules with decreasing the size of microcapsules. These results can be explained as follows: with increasing the concentration of methanol, ethanol or SDS, the viscosity of the nonsolvent increases and the interfacial tension decreases. This lead to a decrease in size of obtained PLG microcapsules and smaller microcapsules are obtained.
Carvedilol-loaded poly(D,L) Lactide nanoparticles/ microparticles : Preparation, Characterization and drug release profile
(2016-03-23) Bani-Odeh, M.
The oral solid dosage forms are the most preferred among other dosage forms because they offer some advantages such as the ease of administration with a high patient compliance, the ease to prepare, transport with high store stability and the low cost of manufacturing processes. Beside of these advantages, the conventional drug release dosage form suffers from various inconvenient that offer many challenges for pharmaceutical industries. Two important factors responsible for these inconvenient are 1) the immediate release of the drug, with little or no control upon the release rate and also 2) their low solubility and/or permeability. One promising method, is the utilization of biodegradable polymer nanoparticles in drug delivery to overcome the disadvantages mentioned previously in the developing of oral solid dosage form. This technology has shown to enhance the solubility and hence; absorption of poorly water-soluble drugs; efficiently target drugs into distant areas in the body; enhance cellular uptake of drugs across tight epithelial and endothelial barriers; deliver two or more drugs using the same carrier. Carvedilol, is an anithypertensive agent that is used widely in the treatment of hypertension and congestive heart failure. However, it suffers from low water solubility which will decrease its oral bioavailability. In this work we aim to prepare Carvedilol poly (D,L) lactide (PDLLA) nanoparticles/microparticles with high loading efficiency and to optimize the size and morphology of the developed particles in order to study the Carvedilol release profile from the obtained particles at room and body temperatures. In this communication, the preparation of the PDLLA nanoparticles and microparticles and their loading with Carvedilol will be presented. A full characterization of the obtained particles by AFM in order to optimize their size and morphology will be discussed. Finally, the Carvedilol release profiles from the PDLLA nanoparticles and microparticles have been determined at room and body temperatures.
CdSe/FTO thin film electrodes prepared by chemical bath, electrochemical and combined elecrochemical/chemical bath depositions: A comparative assessment of PEC characteristics
(2016-03-23) Abdulrahman, Nour
CdSe thin films have been deposited onto fluorine doped tin oxide (FTO/glass) substrates by three different techniques, electrochemical deposition (ECD), chemical bath deposition (CBD) and combined method based on electrochemical deposition (ECD) followed by chemical bath deposition (CBD). The films were comparatively characterized by a number of techniques including (photoluminescence spectra (PL), electronic absorption spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD)). Photo-electrochemical (PEC) characteristics of the electrodes including photo-current density-voltage (J-V) plots, conversion efficiency (ƞ) and fill factor (FF) were then studies. The PEC measurements indicate that all the CdSe films have n-type, and optical absorption measurements show that the prepared films have emission band with almost similar wavelength range (600-540 nm, 2.06 - 2.29 eV), while ECD shows some blue shift (580-520 nm) with higher band gap values (2.06 - 2.29 eV) to (2.132.38) eV. XRD results show that the three systems involved nano-sized CdSe particles with cubic type crystals. The new ECD/CBD-CdSe electrode exhibited higher photoelectrochemical conversion efficiency (ƞ% ̴ 4.40) than either ECD- or CBD-CdSe film electrodes.
Characterization of nanomaterials with low voltage field emission scanning electron microscopy: Promises and challenges
(2016-03-23) Bearat, Hamdallah A.
Use of materials in the form of thin films, layers, coating, nanowires, nanotubes, and nanoparticles is increasingly deployed in many industries. Application varies from semiconductors to memory or optical devices, to catalysis, corrosion, as well as many artistic, chemical, electronic and biomedical fields. In this communication, I report on two years of consulting research work at Agilent Technologies Inc., using the Agilent 8500 Field Emission Low Voltage Scanning Electron Microscope. This scope allows imaging of most types of materials: metals & alloys, minerals & rock, ceramics, semiconductors, polymers, and biological samples, as well as micro- and nano-devices (PV-cell, MEMS, AFM-cantilever, dynamic memory, etc.). It provides images of 5-10nm resolution without the need for sample coating (usually done with Au, C, or Au-Pd in conventional SEMs). The imaging is done at a standard accelerating voltage (AV) of 1000v instead of the conventional voltage of 15-35kV. This low voltage avoids analyst also the charging effects and the radiation damage that may result with insulating specimens from the higher AC or the damage to biological specimens when imaged with and an Environmental Cell Scanning Electron microscope (E-SEM). Data to be presented concern a wide range of materials and address multiple questions on the nature, structure, and application/occurrence of these materials in different contexts (engineering, geological, archaeological or artistic). Major focus shall be given to materials at the nanoscale level.
Complexes formed between DNA and poly(amido amine) dendrimers of different generations
(2016-03-23) Qamhieh, Khawla
Gene therapy holds a promise in healing cancer and other genetic diseases by directly delivering therapeutic DNA into living cells. Although viruses have been demonstrated to be efficient delivery vectors, their toxicity and immunogenicity have limited their general use. Poly (amidoamine) (PAMAM) dendrimers, being protonated under physiological conditions, have great potential as nonviral vectors for gene transfection. Many experimental and simulation studies have been performed to study the effect of dendrimer size, charge, and salt concentration on the structure and transfection efficiency of condensed DNA aggregates. In our study we investigated the complexation of dendrimers with DNA molecule using theoretical model and Coarse-Grained molecular dynamics simulations. Throughout the study, first we emphasized on the effect of the medium’s environments on the complexation of LPE chain with one dendrimer, namely the concentration of 1:1 salt solution, dielectric permittivity of the solvent, and pH conditions. Other factors have been investigated such as size and charge of the dendrimers, degree of polymerization of the LPE chain, and it’s rigidity. Then we investigated the effect of the salt concentration on the interaction between linearized DNA plasmids (4331 bp) and positively charged dendrimers of generations 1, 2, 4, 6 and 8, previously studied experimentally. It is found that in the first case of complexation of LPE chain with one dendrimer, the wrapping degree of the chain around the dendrimer increases by increasing dendrimer’s charge, Bjerum length, length of the LPE chain, and salt concentration. Also, charge inversion of dendrimer is obtained, and the value of the inverted charge increases by increasing the above mentioned parameters. While the complex shows more wrapping degrees, and less inverted charge as the pH of the solution decreases. In the case of complexation of DNA plasmids with dendrimer of different generations, the wrapping length of the LPE chain depends on dendrimer generation. With small generations, the optimal wrapping length of LPE chain around dendrimer increases by increasing the salt concentration, while, the complexation is insensitive to ionic strength with large generations.
Determination of the Variation of the Trapped Charge in Organic Thin Film Transistors during Hysteresis
(2016-03-23) Awawdeh, K. M.
We compare different procedures to extract information about the trapping processes that occur in organic thin film transistors (OTFTs) during hysteresis mechanisms. The procedures are based on models that describe the transistor as the combination of an intrinsic transistor and the contact regions. The models are used to fit experimental output characteristics and to extract the current-voltage curves for the intrinsic transistor. We show the importance of eliminating the effect of the contacts, not only from fundamental parameters such as the mobility and the threshold voltage or the drain–terminal voltage, but also from the gate– terminal voltage. Using a previously developed compact model for the OTFT, this study aims to complement experimental procedures that also propose to eliminate contact effects. A study of the effects of the contact region on the value of the mobility extracted from different models has been made. Also, we have quantified the effect of eliminating the contact region from the gate- and drainterminal voltages, and only from the drain-terminal voltage. A proper extraction of the mobility with a model that incorporates contact effects is essential to obtain good results, even if the terminal voltages are considered instead the intrinsic ones. In this regard, a compact model that describes the output characteristics of the transistor and includes the effect of the contact regions is considered as the best scenario. The worst scenario is when the contact voltage is eliminated partially from the terminal voltages.
Development of Alpha Spectroscopy Method with Solid State Nuclear Track Detector Using Aluminum Thin Films
(2016-03-23) Dwaikat, Nidal
This work presents the development of alpha spectroscopy method with solidstate nuclear track detectors using aluminum thin films. The resolution of this method is high, and it is able to discriminate between alpha particles at different incident energies. It can measure the exact number of alpha particles at specific energy without needing the calibration of alpha track diameter versus alpha energy. This method was tested by using Cf-252 alpha standard source at energies 5.11 Mev, 3.86 MeV and 2.7 MeV, which were produced by the variation of detector -standard source distance. On front side, two sets of detectors (five each), were covered with two Aluminum thin films of different thicknesses and the third set of detectors were kept uncovered. The thickness of Aluminum thin films was selected carefully (using SRIM 2013) such that one of the films will block the lower energy alpha particles (3.86 MeV and 2.7 MeV) while the alpha particles at higher energy (5.11 MeV) can penetrate the film and reach the detector’s surface. The second thin film will block alpha particles at the lowest energy 2.7 MeV and allow alpha particles at higher two energies (5.11 Mev and 3.86 MeV) to penetrate and produce tracks. For quality assurance and accuracy, the detectors were mounted on thick enough copper substrates to block exposure from the backside. For uncovered detector ( third set), alpha particles at three different energies can produce tracks on it. The tracks on the first set of detectors are due to alpha particles at energy of 5.11 MeV. The difference between the tracks number on the first of detectors and the tracks number on the second set of detectors is due to alpha particles at energy of 3.8 MeV. Finally, by subtracting the tracks number on the second set of detectors from the tracks number on the third set of detectors (uncovered), we can find the tracks number due to alpha particles at energy 2.7 MeV. Thus, the discrimination between alpha particles at different incident energies is achieved. Therefore, knowing the efficiency calibration factor, one can exactly calculate the activity of the standard source.
Development of compositionally-tuned mixed-garnet crystals for space applications
(2016-03-23) Aburish-Hmidat, Mahmoud
There are considerable needs in space operations that call for the employment of specific laser sources under mandatory conditions such as highpower, appropriate function wavelengths, flexible lasing and pulse settings, tunability, narrowband, conversion efficiency, laser-beam control, and so on. In areas of space applications such as differential absorption lidar (DIAL), lasers particularly operated around the wavelength peak λ=943nm are recommended key solutions because their spectral emission straightforwardly matches the absorption line of water vapor in the Earth's atmosphere. In the recent years, and as a result of the aforementioned prerequisites, groups of scientists started conducting central research to develop specific laser materials with valid output gain and efficiency suitable to bring about space constraints and preferences in an optical spectral range of interest. Part of the efforts are focused on the development of compositionally tuned crystals which can be obtained by adjusting the concentration of the host constituents in order to alter the spectral emission and shift it towards a particularly desirable wavelength. Mixed-garnet crystals are innovative materials appropriate for tuning a laser emission in the wavelength range λ=935-945nm. In this class of crystals, lanthanide and rare-earth elements share the structure matrix in proportionalities that are controlled during the crystal growth process. This presentation reviews the jobs carried out on assorted mixed-garnet laser crystals produced in Italy by the industrial firm FILAR – Opto Materials (FOM), partly in the framework of space activity projects established by the European Space Agency, and partly on market demand based on prerequisite specifications to build up a series of diode-pumped solid-state lasers (DPSSL) with exceptional capabilities. The crystals considered in this study are the Nd-doped mixed-garnet composites GSAG (gallium scandium aluminum garnet), YAG-YSGG (yttrium aluminum garnet – yttrium scandium gallium garnet), and YSAG-GGG (yttrium scandium aluminum garnet – gadolinium gallium garnet). The presentation reports on the crystal growth of these mixed-garnets, their structural and spectral characterization, fabrication of laser components, and, in some case, laser assessment. Comparison with the properties and performance of Nd:YAG crystals (produced by FOM) will also be enlightened where possible.
Development of Innovative Low Cost POF Sensors for Monitoring Chemical and Environmental Quantities
(2016-03-23) Ishtaiwi, M.
This work aims at the design and development of innovative sensing systems based on optical technology. Plastic Optical Fiber (POF) can be successfully employed for the development of highly sensitive and selective devices to be used in monitoring environmental and chemical quantity. This paper describes an approach to develop low-cost plastic optical fiber sensors suitable for measuring low concentrations of pollutants in the atmosphere, such as low concentrations of hydrogen fluoride (HF) vapors. The sensor is based on plastic optical fibers whose surface is modified in such way to make it sensitive to the presence of specific contaminants (below to 0.1 ppm of HF). The approach proposed for the realization of the sensors foresees the surface modification of the plastic optic fiber in three steps: (i) removing of the cladding by an organic solvent (such as ethyl acetate); (ii) performing a plasma nanotexturing of the core surface using oxygen/argon plasma treatments (iii) deposition of the sensitive thin film (SiO2) able to react with HF by using PECVD (Plasma Enhanced Chemical Vapor Deposition) and/or plasma sputtering. The pollutants (fluoride ions) attack the SiO2 film and alter the transmission capability of the fiber so that the detection simply requires a LED and a photodiode. The sensor exploits a cumulative response which makes it suitable for direct estimation of the total exposure to the fluoride ions.
Dispersion of Iron Nanoparticles on Clay Materials and its Application for the Sequestration of Aqueous Pollutants
(2016-03-23) Shahwan, Talal
During the last decade, iron nanomaterials have been investigated worldwide for the removal of various inorganic and organic aqueous pollutants. The efficiency of the these materials was documented in lab scale experiments. Field studies (in-situ and ex-situ) were also conducted and the materials were reported to be successful in the treatment of polluted water and soil. However, one of the major constrains in field applications of iron nanoparticles stems from their strong aggregation tendency. In order to reduce the aggregation behavior, the particles were synthesized in the presence clay materials, employed as supporting and dispersing agents. Different types of clays and soil minerals were used; kaolinite, montmorillonite, alumina, and clinoptilolite. The resulting composite materials were utilized in the sequestration of aqueous heavy metal ions, ions of rare earth elements, in addition to cationic and anionic dyes, over wide ranges of experimental conditions. High removal percentages and fast kinetics were observed. The primary fixation/removal mechanisms involved redox and sorption reactions, depending on the reduction potential of the particular metal ion. The composite materials were repetitively used and showed high stability.
Effect of polyamines on low methoxyl pectin-based films
(2016-03-23) Sabah, M.
Low methoxyl pectin (LMPEC) contains a high amount of free carboxylic acid groups able to interact withCaP2+Poriginating a gel network. LMPEC gelation primarily involves electrostatic forces between the cation and the negative charged cavity formed by the polymer chains where CaP2+Pare inserted. These structures, calledegg-boxes, are stabilized by both Van der Waals interactions and hydrogen bonds. They are of great importance both in the area of fruit and vegetable processing as well as for the use of LMPEC in various food products. Polyamines (PAs) are low mol.wt organic cations known to mimic the action of divalent cations both in vitro and in vivo. The different length of PA aliphatic chains, thus, stimulated us to investigate their effect on the mechanical and barrier properties of LMPEC-based edible films. In fact, LMPEC represents also a suitable polymeric matrix for the preparation of coating films potentially useful for food active packaging for its biodegradability and biocompatibility. One of the main additives of the bio-based edible films is the plasticizer, generally a small molecule of low volatility, like glycerol or sorbitol, able toimprove film extensibility and flexibilityby increasing both free volume and polymer chain mobility. Therefore, our research focused on the specific comparison among calcium, and the two PAs putrescine (PT) and spermidine (SPD) as possible agents influencing the functionality of LMPEC-based films prepared in the presence or absence of glycerol. Zeta potential and particle size were determined on LMPEC aqueous solutions as a function of pH and the effect of calcium ions, PT and SPD on LMPEC-based films were studied. CaP2+ Pand PAs were found to differently influence thickness, as well as mechanical and barrier properties, of films prepared at pH 7.5 either in the presence or absence of the plasticizer glycerol. In particular, CaP2+ Pwas found to increase film tensile strength and elongation to break only in the presence of glycerol and did not affect film thickness and permeability to both water vapor and COR2R. Conversely, increasing PA concentrations progressively reduced film tensile strength and markedly enhanced film thickness, elongation to break and permeability to water vapor and COR2R, both in the presence and absence of glycerol. Our findings suggest that PAs give rise to a LMPEC structural organization different from that determined by calcium ions, previously described as “egg box” model, and that PAs can be used as effective plasticizers to obtain more flexible and less brittle hydrocolloidal films.
Elaboration and characterization of modified sepiolites and their humidity sensing features for environmental monitoring
(2016-03-23) Hassan, M.
After a simple low cost wet chemical precipitation route under basic conditions and subsequent thermal treatment, different oxide/hydroxide nanoparticles (based onW4+, Co2+, Cu2+, Gd3+, La3+, Mn2+, Nd3+, Sm3+, Sr2+, Y3+ and Zn2+) were formed instead of Mg2+ ions onto the sepiolite (Si12Mg8O30(OH)4.(H2O)4.8H2O) channels. The fact that these nanoparticles appear supported on an inert matrix makes it possible to avoid manipulation, agglomeration and harmful character that pure nanoparticles usually have. Thermogravimetric–Differential Thermal Analysis (TG–DTA) combined with X-ray diffraction (XRD), nitrogen adsorption at −196 °C, Field Emission-Scanning Electron Microscopy (FE-SEM), Diffuse Reflectance UV–visible (DR-UV–vis) spectroscopy and Infra-Red (IR) spectroscopy were used to study the particle size distribution, the morphology and the composition of the modified sepiolites. Sepiolite is known as a high specific surface area (SSA), that is why the thinking about using in sensors is a must. SSA decreases after leaching of sepiolite, whereas, after doping, some oxo/hydroxides formed, as confirmed by UV–vis spectroscopy that could contribute to the increase in SSA. Humidity sensors were prepared in the form of pellets, where powders uniaxially pressed and thermally treated at 550 °C for 1 h then, interdigidated (IDE) gold electrodes were screen-printed. Among the investigated compositions, tungsten-doped sepiolite seems to be the most interesting one, even, if its composition has to be optimized, in order to have responses for lower RH values. This is due to response towards relative humidity (RH) at room temperature starting from 40% RH. In a future work, different amounts of precipitated particles will be investigated.
Electrical properties of the Yb/Ga2S3 interface
(2016-03-23) NazzalU, UEman O.
GaR2RSR3R thin films are deposited onto Ytterbium substrate at vacuum pressure of 10P-5P mbar for use as new class of optoelectronic devices. The Yb/GaR2RSR3R interface is studied by means of current- voltage characteristics, impedance spectroscopy in the frequency range of 1.0 M-1.8 GHz and the power spectroscopy in the frequency range of 1.0 M-3.0 GHz. The studies allowed determining the current conduction mechanism at the interface, the capacitive and inductive reactance, the resonance -antiresonance spectral positions, the inductive region width as well as the notch frequency of wave filtering. The resulting values and behaviors of the frequency dependent parameters indicated that the Yb/GaR2RSR3R heterojunction are promising interface for use as band stop filters and wave traps. These filters are also observed to be tunable through voltage biasing indicating the applicability of the devices as voltage linear oscillator.
Electrochemical properties of Sol-gel WO3 films single doped with Ti and Co-doped with Ti and Zn
(2016-03-23) Albalshi, M.
WO3 nanoparticles single doped with Ti (W1-xTixO3) and co-doped with Ti and Zn (W1-xTix-yZnyO3) have been prepared, onto FTO/glass substrate. Preparation of films was done using wet chemical method (dipping in a sol-gel). The molar concentration of Ti into W1-xTixO3 ranges from 0-30 % in steps of 5%. Best electrochemical and electrochromic properties were observed for composition that has Ti nominal concentration of 5 % (W0.95Ti0.05O3). This was evidenced from measurements of cyclic voltammetry (CV), chronoamperometry (CA), and transparency during CA. The composition that gives best electrochemical and electrochromic properties (W0.95Ti0.05O3) was used to prepare WO3 nanocrystallite films co-doped with Zn for the first time (W0.95Ti0.05yZnyO3). The Zn molar concentration in these films varied from 1-5%. From CV, CA, and transparency measurements, the best electrochemical and electrochromic properties were observed for films that contains 3% of Zn (W0.95Ti0.02Zn0.03O3). Moreover, this film was found to have better electrochemical and electrochromic properties than single doped WO3 film (W0.95Ti0.05O3). In addition, higher electrochemical stability was observed for co-doped films.
Electrochromic Properties of WO3 doped with Ti and Zn atoms
(2016-03-23) Ghanma, S.
WO3 electrochromic thin films doped with Ti and/or co doped with Zn atoms have been prepared by sol-gel technique onto FTO/Glass substrates. WO3 doped with 0.05% of Ti (W0.95Ti0.05O3) was co doped with Zn molar concentration varies according to W0.95Ti0.05-xZnx , where x ranges from 0 - 5 %. For these films, different electrochromic parameters have been studied. Cyclic voltammetry (CA), Chronoamperometry (CA), and transparency during CA was used to study the electrochromic parameters. Best electrochromic properties was observed for codoped film with nominal composition of W0.95Ti0.03Zn0.02. Compared to all studied films, this film (W0.95Ti0.03Zn0.02) showed the highest contrast ration (TRbR/TRcR ≈ 1.85). Also, this film has highest coloration efficiency (60 cmP2P/C), which is 2.2 times higher than WO3 doped with Ti alone (W0.95Ti0.05). Moreover, co-doped film has a good switching time and excellent reversibility (Qa/Qc ≈ 0.95 ), which are almost same as single doped film.

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