bluuebunny/crossref_metadata_2025 huggingface dataset:
EVALUATION OF NANOCRYSTALLINE BA(ZRXTI1-X)O3 PRODUCED BY MECHANICAL ALLOYING
Authors: Hajfathalian M. , Nemati Z. A. , Madaah Hosseini H. R.
Published: March 2012

BaTiO 3-based solid solutions involve high piezoelectric and ferroelectric properties. One of the most favorable systems of this material is Ba ( Zr x Ti 1- x ) O 3. While nano structured ceramics of which have a great potential for using them in capacitors, actuators, transducers and dielectrics to reach high K values. In this study, nano crystalline Ba ( Zr x Ti 1- x ) O 3( x =0.1-0.8) which is called BZT composite has been prepared by mechanical alloying. The parameters affecting the process and properties were evaluated. The starting powders that are used here were nano sized high pure ZrO 2; submicron sized high pure TiO 2 and BaCO 3. The prepared powder was calcined, compacted and sintered at different temperatures and in various times. The structural changes and phase developments during mechanical alloying were studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The results showed that by using mechanical alloying method, high dense nano crystalline BZT ceramics were obtained successfully at very low sintering temperature. The dielectric constant of BZT was much great, because of using nano materials in this method at the temperatures of 1250-1400°C. The effect of high energy milling in micro structural development of nano crystalline BZT has been discussed as well as dielectric properties.
STUDY OF PROCESSING AND MECHANICAL BEHAVIOR OF PP/CLAY NANOCOMPOSITES PREPARED BY MELT BLENDING
Authors: SHIRAZI SAREH MOSLEH , JANGHORBAN KAMAL
Published: March 2012

In this research, the melt blending technique was used to prepare various polypropylene (PP) based nanocomposites containing 1,3,5,7 wt% montmorillonite (MMT). A commercial organoclay (denoted K-10) served as the filler for PP matrix and the polypropylene grafted maleic anhydride (PP-g-MA) was used as compatibalizer. The morphology of the nanocomposites was studied by X-ray diffraction (XRD), results of which showed that the nanocomposites are best described as intercalated-exfoliated systems. PP/MMT nanocomposites showed good thermal stability in the TGA analysis. Introducion of ~ 3% MMT in the nanocomposites increased the onset temperature of the degradation by 27.5 °C compared to that of pure PP. Test results showed that PP/clay nanocomposites had an enhanced tensile strength, hardness and decreased wear rates.
EFFECT OF MgO NANO PARTICLES ON SINTERING BEHAVIOR OF Al2O3-SiC-MgO NANO COMPOSITES
Authors: SURANI FERESHTEH , ABDIZADEH HOSSEIN , BAHARVANDI HAMID REZA , NEMATI ALI
Published: March 2012

Small amount of MgO in the range of ppm and distribution of SiC particles in Al 2 O 3-10 vol % SiC nanocomposite has an obvious effect on improving of density and mechanical properties such as hardness of sintered nanocomposite. Improving of these properties continues to 1000 ppm of MgO , but decreases above this amount. Transgranularly fractured alumina grains were observed on the fracture surface of this kind of nanocomposites. The effects of such a small amount of MgO on the sintering and microstructural development of Al 2 O 3-10 vol % SiC nanocomposite may be explained using the arguments which have been documented for the beneficial effects of a small amount of MgO in alumina ceramics. In Al 2 O 3-10 vol % SiC nanocomposite, Al 2 O 3 particles were coated by nano scale SiC particles which inhibited the abnormal grain growth of Al 2 O 3.
ROLE OF PROCESS CONTROL AGENTS ON MILLING BEHAVIOR OF Al AND TiO2 POWDER MIXTURE TO SYNTHESIZE TiAl/Al2O3 NANO COMPOSITE
Authors: ALAMOLHODA S. , HESHMATI-MANESH S. , ATAIE A. , BADIEI A.
Published: March 2012

In this study effect of adding various process control agents (PCAs) to powder mixtures of Al and TiO 2 which are mechanically activated so as to form TiAl - Al 2 O 3 nano-composite have been investigated. Phase constitutions and morphology of the milled powders were evaluated by XRD and SEM techniques, respectively. The mean crystallite sizes of the milled powders were calculated by Cauchy-Gaussian method. Thermal behavior of the milled powders was also studied by DTA to investigate formation of the final phases. The results showed that the mean crystallite size of the milled powders in the presence of PCAs was smaller than that of the sample milled without PCA addition. DTA traces showed that addition of PCAs retards the reduction of TiO 2 by Al . In samples milled in presence of PCA, the reductive reaction generally took place after melting of Al particles whereas the sample milled without PCA addition showed an opposite behavior. Also, in comparison with the sample milled with no PCA addition, in other samples the reductive reaction took place at relatively lower temperatures.
MICROSTRUCTURE AND WEAR RESISTANCE OF A COMPOSITE Gr/Al2O3/Al PRODUCED BY RECIPROCATING EXTRUSION
Authors: Zhang Z. M. , Zhu G. P. , Xu C. J. , Hu B.
Published: March 2012

A reciprocating extrusion process was used to produce graphite and alumina reinforced pure aluminium composite. The graphite particles (0~5vol%), alumina particles (10 vol%) and pure aluminium particles (balanced) were dehydrated separately at 70°C in vacuum for 3 hours, and then mixed together. A round billet with 50 mm in diameter was prepared by hot pressing at 350°C with the mixed particles and then extruded to a fully-consolidated goblet-like sample at 480°C and 430MPa by reciprocating extrusion. The results showed that all reinforced particles were refined and uniformly distributed in the matrix by reciprocation extrusion severe plastic deformation. The presence of graphite particles caused the reduction in the friction coefficient and wear rate of the Gr / Al 2 O 3/ Al composite. Compared with the composite prepared only by alumina particles (10 vol%) and pure aluminium particles, the friction coefficient and wear rate of the Gr / Al 2 O 3/ Al composite, which contains 5vol% graphite and 10vol% alumina particles, decreased 45.3% and 33.5%, respectively, and thereafter it displays an excellent combination of low friction coefficient (0.37) and wear rate (2.2×10-7mm3/(N.m)), and appears to be more promising.
GROWTH KINETICS OF ALUMINIDE LAYERS ON NANOCRYSTALLINE NICKEL
Authors: RASHIDI A.M. , AMADEH A.
Published: March 2012

In this research, the simultaneous growth of Al 3 Ni 2 and Al 3 Ni on nanocrystalline nickel was investigated. Nanocrystalline nickel samples with mean grain size of about 25 nm were prepared by direct current electroplating. The samples were aluminized for different durations by pack cementation method at 500, 550 and 600 °C. The aluminide phases were identified by SEM, EDS and XRD. In contrast to reported results suggesting the formation single layer of Al 3 Ni 2 phase on coarse grained nickel, it was observed that long time aluminizing of nanocrystalline nickel resulted in the formation and simultaneous growth of two distinct layers of Al 3 Ni 2 and Al 3 Ni phases. The growth of both phases followed the parabolic growth kinetics, but the growth rate constant of Al 3 Ni 2 was much greater than Al 3 Ni layer. Also, the simultaneous growth of Al 3 Ni 2 and Al 3 Ni was modeled. Based on this model, the activation energy of the coating growth (total Al 3 Ni 2 and Al 3 Ni layers) was determined as about of 178 kJ/mol.
Nanostructured phothocatalytic TiO2 thin film fabricated by magnetron sputtering on glass
Authors: ABDOLLAHI NEJAND BAHRAM , SANJABI SOHRAB , AHMADI VAHID
Published: March 2012

TiO 2 thin film was deposited by a DC reactive magnetron sputtering on ZnO /soda-lime glass substrate and single crystal SiO 2 below 200 °C. ZnO layer was used as a buffer layer. Deposition was performed at Ar + O 2 gas mixture with a pressure of 1.0 Pa and oxygen with a constant pressure of 0.2 Pa. The TiO 2 / ZnO thicknesses were approximately 1000 nm and 80 nm, respectively. As-deposited films were annealed at 400 °C. The structure and morphology of deposited layers were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The transmittance of the films was measured using ultraviolet–visible light (UV–vis) spectrophotometer. Photocatalytic activities of the samples were evaluated by the degradation of 2-propanol. The microstructure of annealed films was anatase, having improved photocatalytic activity. The surface grain size of TiO 2 thin film after annealing was found about 25-35 nm and crystal size was approximately 8 nm. By using ZnO thin film as buffer layer, the photocatalytic property of TiO 2 films was improved.
OPTIMIZATION OF NANOSTRUCTURED BLACK ELECTROLESS Ni-P COATING FOR SOLAR ABSORBER
Authors: HOSSEINI NAJAFABADI M. , ASHRAFIZADEH F. , MONIRVAGHEFI M.
Published: March 2012

High solar absorber coatings of Ni - P on aluminum substrate have been fabricated by electroless technique as an alternative to complex PVD coatings. For this purpose, the Ni - P coating was deposited on commercially pure aluminum and then blacking process was carried out. Upon heat treatment, the amorphous structure of the coatings transformed to a nanocrystalline structure which is accompanied by variation in properties. The phase structure of the coatings was studied by X-ray diffraction; the crystallite size measured by using Sherrer method indicated an average crystallite size of about 15 nm with an increase in hardness. Morphological studies of coatings were performed by scanning electron microscopy. The coatings generally had a sound, crack-free surface with a thickness value of around 10μm. The optical properties of the coatings were determined by means of spectrophotometer. The black electroless nickel possessed higher absorption in the range of visible light, with a coefficient in the order of 0.98. The results of this study indicate that the coating process described herein is suitable as solar absorber coating.
IMPROVED CORROSION RESISTANCE OF NANOSTRUCTURED COPPER DEPOSITED BY EB-PVD IN ACIDIC MEDIA
Authors: Saremi M. , Yeganeh M.
Published: March 2012

Electron Beam-Physical Vapor Deposition (EB-PVD) is being used in coating component for many applications such as electronic industry for producing nanostructures and ICs coatings. In this work, nanostructured copper was deposited on glass using EB-PVD technique. Surface and elemental characteristics of EB-PVD coatings investigated and evidenced corrosion resistance of nanostructured coatings produced by this technique are higher than Cu sheet in chloride media.
EFFECTS OF SODIUM CITRATE AND CURRENT DENSITY ON ELECTROPLATED NANOCRYSTALLINE COBALT-IRON THIN FILMS
Authors: ADELI BEHTAM , HYDARZADEH SOHI MAHMOUD , MEHRIZI SAEED
Published: March 2012

Effects of sodium citrate dosage and current density on composition and phase structure of nanocrystalline CoFe thin films were systematically studied. Energy dispersive spectroscopy (EDS) showed when sodium citrate dosage in the bath was less than 10 g/L, with increasing citrate in the bath, iron content in the deposited films remarkably decreased. However, sodium citrate dosage more than 20 g/L had no effect on composition of the deposited films. In low current densities, cobalt content decreases and iron content increases, as the current density increases. The current density of 15 ma/cm2 could be considered as alloy limiting current density. The XRD analyses showed that only BCC and/or FCC formed in the deposited films and average grain size, estimated by Scherrer formula, were below 55 nm. The results indicated that phase formation in the electrodeposition of CoFe deviated from equilibrium conditions and was controlled by kinetic conditions. The lattice constants for BCC and FCC phases in CoFe films were close to those of BCC iron and FCC cobalt, respectively.
PRELIMINARY STUDY OF ELECTROPHORETIC DEPOSITION OF VERTICALLY ALIGNED MWCNT ON METALLIC ELECTRODE
Authors: KHABAZIAN SIAVASH , SANJABI SOHRAB
Published: March 2012

Multi-walled carbon nanotubes films formed randomly aligned laterally by electrophoresis. Multi-walled carbon nanotubes with lengths of about 10 μ was shortened and functionalized by a mixture of sulfuric and nitric acid. The functional groups on carbon nanotubes were elaborated by FT-IR. Chemically shortened MWCNTs disperse in organic and aqueous solvent and deposited on electrode vertically-aligned by applying a constant DC electric field. The alignment of MWCNTs was observed by scanning electron microscopy. It also the effect of various substrates on alignment of multi-walled carbon nanotubes was investigated.
MICROSTRUCTURAL EVALUATION OF NANOCRYSTALLINE COBALT-IRON-NICKEL THIN FILMS ELECTRODEPOSITED FROM CITRATE-FREE AND CITRATE-ADDED BATHS
Authors: MEHRIZI SAEED , HYDARZADEH SOHI M. , SEYYED EBRAHIMI S. A.
Published: March 2012

The microstructures of nanocrystalline CoFeNi thin films in direct current electrodeposition, under various processing conditions, have comparatively been investigated. Morphological studies by SEM showed that CoFeNi films plated from the sodium citrate-added baths were more uniform and denser than those deposited from the conventional citrate-free baths. Energy dispersive spectroscopy (EDS) showed the anomalous behaviors in electrodeposition of CoFeNi films from both citrate-added and citrate-free baths. It was also noticed that addition of 10g/L sodium citrate in the bath strongly decreases the iron content and increases nickel contents of the deposit. Addition of citrate up to 50g/L in the bath has reverse effect on the film composition. Further addition of sodium citrate appears to have no or little effect on the film composition. Addition of sodium citrate to the bath has no significant affect on the cobalt content of the deposit. XRD analyses showed that all CoFeNi films were nanocrystalline and their average grain sizes, estimated by Scherrer formula, were below 80nm. It was also noticed that FCC and BCC phases could be co-deposited in electroplated CoFeNi films by controlling the bath composition and/or the plating conditions.
EFFECT OF OPERATING TEMPERATURE ON STRUCTURE PROPERTIES OF TICX NANOPARTICLE COATING APPLIED BY PACVD
Authors: Shanaghi Ali , Sabour Rouhaghdam Ali Reza , Ahangarani Shahrokh , moradi Hadi , Mohammadi Ali
Published: March 2012

Titanium carbide ( TiC ) is a widely used hard coating to improve the wear resistance and lifetime of tools because of its outstanding properties such as high melting point, high hardness, corrosion resistance and abrasion resistance. These properties were drastically improved by using nanotechnology. So in this project, TiC x was applied on hot-working die steel (H11) by Plasma CVD (PACVD). The effect of operating temperatures on TiC x structure properties have been studies by typical and advanced analyses methods such as SEM, XRD, FTIR and Raman. The best properties of TiC x nanoparticle, such as nanostructure, mechanical properties and chemical properties, were obtained at 480 °C.
ELECTRIDEPOSITION AND WEAR BEHAVIOR OF NANO-STRUCTURED Cr-WC COMPOSITE COATINGS FROM A TRIVALENT CHROMIUM BATH
Authors: AMADEH A. , NADALI S. , LARI BAGHAL S.M. , MORADI H.
Published: March 2012

Electrodeposition of nano-structured Cr - WC had been carried out from a trivalent chromium bath using a square shaped pulse current. The average size of WC particles was 70 nm. The effect of sodium saccharin and sodium dodecyl sulfate (SDS) additives as well as pulse electroplating parameters such as current density, duty cycle and frequency on the amount of incorporated WC particles and morphology of the coatings was investigated. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. In addition, the hardness and tribological behavior of the coatings were investigated by microhardness and pin on disk methods, respectively. The results showed that although the addition of saccharin and SDS decreased the amount of WC particles in the coating, but reduced the size of WC agglomerates which, in turn, increased the wear resistance of the coatings. Also, the optimum wear resistance was achieved at the current density of 8 A/dm2, duty cycle of 50% and frequency of 10 Hz.
SURFACTANT-ASSISTED SOL-GEL AUTO-COMBUSTION SYNTHESIS OF SR-HEXAFERRITE NANOPOWDER USING DIFFERENT FUELS AND BASIC AGENTS
Authors: GHOBEITI HASSAB M. , SEYYED EBRAHIMI S. A. , DEHGHAN R.
Published: March 2012

In this research Sr -hexaferrite powder was synthesized by a sol–gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N -decyltrimethylammonium bromide ( C 13 H 30 BrN ) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800 °C respectively, in the presence of citric acid, trimethylamine and surfactant.
OPTIMIZATION of DYNAMIC CH4 GAS HEAT TREATMENT OF NANOCRYSTALLINE STRONTIUM HEXAFERRITE
Authors: DEHGHAN R. , SEYYED EBRAHIMI S. A. , KOOHDAR H. R.
Published: March 2012

In this research the influence of dynamic CH 4 heat treatment on Sr -hexaferrite has been investigated. With the gas heat treatment, the phase composition, particles size and the morphology of Sr -hexaferrite change significantly. Due to this, the hard magnetic nature of the material changes from hard to soft.

The strontium hexaferrite powder was prepared by conventional route with calcination of the mixture of strontium carbonate and hematite at 1100°C for 1 hour. Then the resultant Sr -hexaferrite was isothermally heat treated in methane dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions were obtained at 950°C and 15CC/min flow for 0.5 hour.

The effects of gas heat treatment on the phase composition and the particles size and morphology were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibration Sample Magnetometery (VSM) techniques.

The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant iron was also measured below 50nm.
SYNTHESIS AND CHARACTERIZATION OF BaFe12O19 THIN FILMS USING SUSPENSION OF NANO POWDERS
Authors: SALEMIZADEH SAMAN , SEYYED EBRAHIMI S. A.
Published: March 2012

BaM thin films have been synthesized by dispersing the dried gel nano powders prepared by Sol-Gel method. The solution was made by dissolving iron nitrate Fe ( NO 3).9 H 2 O , barium nitrate Ba ( NO 3)2 and citric acid in deyonized water and methanol. This sol was slowly evaporated until a dried gel was formed. This dried gel was then added to ethylene glycol. The final solution was vigorously shaken and mixed in ultrasonic cleaner for 30 min to disperse particles sufficiently. Then the prepared solution spin coated on Si (110) substrate. The obtained thin films were dried at 120 °C and then calcined at 900 °C for 1 h. The films were characterized using X-ray diffraction (XRD) and vibrating sample magnetometer (VSM).
THE INFLUENCE OF GRAIN SIZE OF PURE IRON METAL ON CORROSION INHIBITION IN PRESENCE OF SODIUM NITRITE
Authors: AFSHARI VAHID , DEHGHANIAN CHANGIZ
Published: March 2012

The effects of grain size reduction on the corrosion inhibition of sodium nitrite were investigated using polarization curves and electrochemical impedance spectroscopy (EIS). Nanocrystalline iron (~ 45 nm) was produced by pulse electrodeposition using citric acid bath. The grain size of a nanocrystalline surface was analyzed by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM). The most intensive first-order peak (211) of the XRD patterns was taken for detailed analysis using a Gaussian fitting curve. The tests were carried out in 25 mg / l NaCl + 57 mg / l Na 2 SO 4 with different concentration of sodium nitrite aqueous solutions.

The results revealed that due to the adsorption process which leads to the formation of a protective layer with a greater charge transfer resistance the inhibition effect and corrosion protection of sodium nitrite inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The standard free energy of adsorption ( ΔGads ) revealed a strong interaction between inhibitor and nanocrystalline surface. This was attributed to the increased number of the active sites caused by nanocrystalline surface.
THE EFFECTS OFTI/PTBOTTOM ELECTRODE ON CRYSTALLOGRAPHIC AND SURFACE CHARACTERISTICS OFPZTTHICK FILMS
Authors: KOOCHEKZADEH ALI , KESHAVARZ ALAMDARI ESKANDAR , BARZEGAR ABDOLGHAFAR
Published: March 2012

The ceramic lead zirconate titanate ( PZT ) films near the morphotropic phase boundary are successfully integrated into MEMS devices, especially for applications in microsensors and actuators. The ferro/piezo electric properties of PZT thick films are widely dependent on its surface quality and crystallographic orientation growth. This paper indicates the influences of platinum bottom electrode on the surface and crystallographic properties of PZT . Ti (10 nm ) and Pt (100 nm ) thin films have been deposited on silicon substrate by thermal evaporation and electron beam respectively without vacuum breaking. After annealing treatment, the Pt film exhibited (111) preferred orientation. Finally one micron thick PZT (54/46) film was deposited by a RF magnetron sputtering at room temperature in pure Argon followed by a conventional post annealing treatment on silicon substrate. The XRD measurements have shown the provskite structure of PZT films with (100) preferred orientation at annealing temperatures above 600°C and (111) preferred orientation above 650°c. The SEM results demonstrate that whatever the annealing temperature is increased, recrystallization grains and black holes on Pt surface occurs and cause morphological change of PZT surface. The AFM test shows the strong RMS roughness of platinum surface after annealing temperature at 650°C.
AN EVALUATION OF NI-P AND NI-P/NANO-SIO2 COATINGS ON SWEET CORROSION OF API-5L-X70 PIPELINES STEELS
Authors: ALLAHKARAM S.R. , MAMAGHANI S. , RABIZADEH T.
Published: March 2012

Carbon and low alloy steels are the most commonly used construction materials for oil and gas pipelines. In order to improve their performance, various types of coatings are frequently applied on them. Electroless nickel composite coatings containing nano-particles are widely used on steel substrates. In this paper, CO 2 corrosion of X70 carbon steel coated with Ni - P and Ni - P -nano SiO 2 in 3%Wt NaC1 electrolyte, saturated with CO 2 at 85°C and pH 6.5 in 1bar CO 2 pressure for 72 h, was investigated and the results were compared against each other. SEM and XRD techniques were used for investigating the corrosion products morphology and composition, respectively. In addition, the corrosion process was studied using EIS technique. The experimental results showed that the formation of FeCO 3 protective film on coated samples was limited. Moreover, the addition of SiO 2 nano-particles to Ni - P coating improved corrosion resistance of the substrate, which also showed the ability of nano-particle addition to the Ni - P coating in decreasing the corrosion rate.
AN INVESTIGATION ON EFFECTS OF TiO2 NANO-PARTICLES INCORPORATED IN ELECTROLESS NiP COATINGS' PROPERTIES
Authors: Allahkaram S.R. , Salmi S. , Tohidlou E.
Published: March 2012

Electroless composite coatings have been vastly used in various industries during last decades due to their good properties, such as corrosion and wear resistance, hardness and uniform thickness. In this paper, co-deposition of TiO 2 nano-particles with Nickel-Phosphorus electroless coatings on API-5L-X65 steel substrates was investigated. Surface morphology and composition of coatings were studied via SEM and EDX, respectively. XRD analyses showed that these coatings had amorphous structure with TiO 2 crystalline particles. TiO 2 nano-particles increased microhardness of coatings. Corrosion resistance of these coatings was tested using linear polarization in 0.5M sulfuric acid electrolyte. Results showed that NiP - TiO 2 electroless composite coatings increased corrosion resistance of substrates.
EFFECT OF NANOCRYSTALLIZATION ANNEALING ON MAGNETIC PROPERTIES AND MAGNETOIMPEDANCE OF CO-BASE RIBBONS
Authors: KEYVANARA AMIR , GHOLAMIPOUR REZA , MIRDAMADI SHAMSEDIN , SHAHRI FARZAD , SEPEHRI AMIN HOSSEIN
Published: March 2012

Melt spun ribbons of Co 64 Fe 4 Ni 2 B 19 Si 8 Cr 3 alloy have been prepared and the nanocrystallization process was carried out by the heat treatment of the as spun ribbons above the crystallization temperature. Structural studies of the samples have been performed by transmission electron microscopy and X-ray diffraction. Magnetic properties of the samples and magnetoimpedance measurements were investigated and it was revealed that magnetic properties and magnetoimpedance of the samples deteriorate by the formation of nanocrystalline phases.
Increased Aβ production prompts the onset of glucose intolerance and insulin resistance
Authors: Jiménez-Palomares Margarita , Ramos-Rodríguez Juan José , López-Acosta José Francisco , Pacheco-Herrero Mar , Lechuga-Sancho Alfonso M. , Perdomo Germán , García-Alloza Mónica , Cózar-Castellano Irene
Published: March 2012

Type 2 diabetes (T2D) mellitus and Alzheimer's disease (AD) are two prevalent diseases with comparable pathophysiological features and genetic predisposition. Patients with AD are more susceptible to develop T2D. However, the molecular mechanism linking AD and T2D remains elusive. In this study, we have generated a new mouse model to test the hypothesis that AD would prompt the onset of T2D in mice. To test our hypothesis, we crossed Alzheimer APPswe/PS1dE9 (APP/PS1) transgenic mice with mice partially deficient in leptin signaling ( db/+). Body weight, plasma glucose, and insulin levels were monitored. Phenotypic characterization of glucose metabolism was performed using glucose and insulin tolerance tests. β-Cell mass, islet volume, and islet number were analyzed by histomorphometry. APP/PS1 coexpression in mice with intact leptin receptor signaling did not show any metabolic perturbations in glucose metabolism or insulin sensitivity. In contrast, APP/PS1 coexpression in db/+ mice resulted in nonfasting hyperglycemia, hyperinsulinemia, and hypercholesterolemia without changes in body weight. Conversely, fasting blood glucose and cholesterol levels remained unchanged. Coinciding with altered glucose metabolism, APP/PS1 coexpression in db/+ mice resulted in glucose intolerance, insulin resistance, and impaired insulin signaling. In addition, histomorphometric analysis of pancreata revealed augmented β-cell mass. Taken together, these findings provide experimental evidence to support the notion that aberrant Aβ production might be a mechanistic link underlying the pathology of insulin resistance and T2D in AD.
The role of estrogen receptor-α and its activation function-1 for growth plate closure in female mice
Authors: Börjesson A. E. , Windahl S. H. , Karimian E. , Eriksson E. E. , Lagerquist M. K. , Engdahl C. , Antal M. C. , Krust A. , Chambon P. , Sävendahl L. , Ohlsson C.
Published: March 2012

High estradiol levels in late puberty induce growth plate closure and thereby cessation of growth in humans. In mice, the growth plates do not fuse after sexual maturation, but old mice display reduced longitudinal bone growth and high-dose estradiol treatment induces growth plate closure. Estrogen receptor (ER)-α stimulates gene transcription via two activation functions (AFs), AF-1 and AF-2. To evaluate the role of ERα and its AF-1 for age-dependent reduction in longitudinal bone growth and growth plate closure, female mice with inactivation of ERα (ERα−/−) or ERαAF-1 (ERαAF-10) were evaluated. Old (16- to 19-mo-old) female ERα−/−mice showed continued substantial longitudinal bone growth, resulting in longer bones (tibia: +8.3%, P < 0.01) associated with increased growth plate height (+18%, P < 0.05) compared with wild-type (WT) mice. In contrast, the longitudinal bone growth ceased in old ERαAF-10mice (tibia: −4.9%, P < 0.01). Importantly, the proximal tibial growth plates were closed in all old ERαAF-10mice while they were open in all WT mice. Growth plate closure was associated with a significantly altered balance between chondrocyte proliferation and apoptosis in the growth plate. In conclusion, old female ERα−/−mice display a prolonged and enhanced longitudinal bone growth associated with increased growth plate height, resembling the growth phenotype of patients with inactivating mutations in ERα or aromatase. In contrast, ERαAF-1 deletion results in a hyperactive ERα, altering the chondrocyte proliferation/apoptosis balance, leading to growth plate closure. This suggests that growth plate closure is induced by functions of ERα that do not require AF-1 and that ERαAF-1 opposes growth plate closure.
Raman Laser Polymerization ofC60Nanowhiskers
Authors: Kato Ryoei , Miyazawa Kun'ichi
Published: March 2012

Photopolymerization ofC60nanowhiskers (C60NWs) was investigated by using a Raman spectrometer in air at room temperature, since the polymerizedC60NWs are expected to exhibit a high mechanical strength and a thermal stability. ShortC60NWs with a mean length of 4.4 μm were synthesized by LLIP method (liquid-liquid interfacial precipitation method). TheAg(2) peak ofC60NWs shifted to the lower wavenumbers with increasing the laser beam energy dose, and an energy dose more than about 1520 J/mm2was found necessary to obtain the photopolymerizedC60NWs. However, excessive energy doses at high-power densities increased the sample temperature and lead to the thermal decomposition of polymerizedC60molecules.
Direct Method for Resolution of Optimal Control Problem with Free Initial Condition
Authors: Kahina Louadj , Mohamed Aidene
Published: March 2012

The theory of control analyzes the proprieties of commanded systems. Problems of optimal control (OC) have been intensively investigated in the world literature for over forty years. During this period, series of fundamental results have been obtained, among which should be noted the maximum principle (Pontryagin et al., 1962) and dynamic programming (Bellman, 1963). For many of the problems of the optimal control theory (OCT), adequate solutions are found (Bryson and Yu-chi, 1969, Lee and Markus, 1967, Gabasov and Kirillova, 1977, 1978, 1980). Results of the theory were taken up in various fields of science, engineering, and economics. The present paper aims at extending the constructive methods of Balashevich et al., (2000) that were developed for the problems of optimal control with the bounded initial state is not fixed are considered.
Coupled Fixed Point Theorems under Weak Contractions
Authors: Cho Y. J. , Kadelburg Z. , Saadati R. , Shatanawi W.
Published: March 2012

Cho et al. [Comput. Math. Appl. 61(2011), 1254–1260] studied common fixed point
theorems on cone metric spaces by using the concept of c‐distance. In this paper, we prove
some coupled fixed point theorems in ordered cone metric spaces by using the concept of
c‐distance in cone metric spaces.
Analytical Expressions Pertaining to the Concentration of Substrates and Product in Phenol-Polyphenol Oxidase System Immobilized in Laponite Hydrogels: A Reciprocal Competitive Inhibition Process
Authors: Indira K. , Rajendran L.
Published: March 2012

Theoretical analysis corresponding to the diffusion and kinetics of substrate and product in an amperometric biosensor is developed and reported in this paper. The nonlinear coupled system of diffusion equations was analytically solved by Homotopy perturbation method. Herein, we report the approximate analytical expressions pertaining to substrate concentration, product concentration, and current response for all possible values of diffusion and kinetic parameters. The numerical solution of this problem is also reported using Scilab/Matlab program. Also, we found excellent agreement between the analytical results and numerical results upon comparison.
Trends in Decline of Antiretroviral Resistance among ARV-Experienced Patients in the HIV Outpatient Study: 1999–2008
Authors: Buchacz Kate , Baker Rose , Ward Douglas J. , Palella Frank J. , Chmiel Joan S. , Young Benjamin , Yangco Bienvenido G. , Novak Richard M. , Brooks John T.
Published: March 2012

Background. Little is known about temporal trends in frequencies of clinically relevant ARV resistance mutations in HIV strains from U.S. patients undergoing genotypic testing (GT) in routine HIV care.Methods. We analyzed cumulative frequency of HIV resistance among patients in the HIV Outpatient Study (HOPS) who, during 1999–2008 and while prescribed antiretrovirals, underwent GT with plasma HIV RNA >1,000 copies/mL. Exposure ≥4 months to each of three major antiretroviral classes (NRTI, NNRTI and PI) was defined as triple-class exposure (TCE).Results. 906 patients contributed 1,570 GT results. The annual frequency of any major resistance mutations decreased during 1999–2008 (88% to 79%,P=0.05). Resistance to PIs decreased among PI-exposed patients (71% to 46%,P=0.010) as exposure to ritonavir-boosted PIs increased (6% to 81%,P<0.001). Non-significant declines were observed in resistance to NRTIs among NRTI-exposed (82% to 67%), and triple-class-resistance among TCE patients (66% to 41%), but not to NNRTIs among NNRTI-exposed.Conclusions.HIV resistance was common but declined in HIV isolates from subgroups of ARV-experienced HOPS patients during 1999–2008. Resistance to PIs among PI-exposed patients decreased, possibly due to increased representation of patients whose only PI exposures were to boosted PIs.
Medium-Term Earthquake Forecast Using Gravity Monitoring Data: Evidence from the Yutian and Wenchuan Earthquakes in China
Authors: Zhu Yiqing , Zhan F. Benjamin
Published: March 2012

Gravity changes derived from regional gravity monitoring data in China from 1998 to 2005 exhibited noticeable variations before the occurrence of two large earthquakes in 2008 in China—the 2008 Yutian (Xinjiang)Ms=7.3earthquake and the 2008 Wenchuan (Sichuan)Ms=8.0earthquake. Based on these gravity variations, a group of researchers at the Second Crust Monitoring and Application Center of China Earthquake Administration made a suggestion in December of 2006 that the possibility for the Yutian (Xinjiang) and Wenchuan (Sichuan) areas to experience a large earthquake in either 2007 or 2008 was high. We review the gravity monitoring data and methods upon which the researchers reached these medium-term earthquake forecasts. Experience related to the medium-term forecasts of the Yutian and Wenchuan earthquakes suggests that gravity changes derived from regional gravity monitoring data could potentially be a useful medium-term precursor of large earthquakes, but significant additional research is needed to validate and evaluate this hypothesis.
Effect of Seasonality and Ecological Factors on the Prevalence of the Four Malaria Parasite Species in Northern Mali
Authors: Koita Ousmane A. , Sangaré Lansana , Sango Hammadoun A. , Dao Sounkalo , Keita Naffet , Maiga Moussa , Mounkoro Mamadou , Fané Zoumana , Maiga Abderrhamane S. , Traoré Klénon , Diallo Amadou , Krogstad D. J.
Published: March 2012

Background. We performed 2 cross-sectional studies in Ménaka in the Northeastern Mali across 9 sites in different ecological settings: 4 sites have permanent ponds, 4 without ponds, and one (City of Ménaka) has a semipermanent pond. We enrolled 1328 subjects in May 2004 (hot dry season) and 1422 in February 2005 (cold dry season) after the rainy season.Objective.To examine the seasonality of malaria parasite prevalence in this dry northern part of Mali at the edge of the Sahara desert.Results. Slide prevalence was lower in hot dry than cold dry season (4.94 versus 6.85%,P=0.025). Gametocyte rate increased to 0.91% in February. Four species were identified.Plasmodium falciparumwas most prevalent (74.13 and 63.72%).P. malariaeincreased from 9.38% to 22.54% in February. In contrast, prevalence ofP. vivaxwas higher (10.31%) without seasonal variation. Smear positivity was associated with splenomegaly (P=0.007). Malaria remained stable in the villages with ponds (P=0.221); in contrast, prevalence varied between the 2 seasons in the villages without ponds (P=0.004).Conclusion. Malaria was mesoendemic; 4 species circulates with a seasonal fluctuation forPlasmodium falciparum.
High-Performance Liquid Chromatography Assay for Moxifloxacin in Brain Tissue and Plasma: Validation in a Pharmacokinetic Study in a Murine Model of Cerebral Listeriosis
Authors: Respaud Renaud , Grayo Solene , Singlas Eric , Dubouch Sophie , Le Monnier Alban , Lott Marie-Catherine
Published: March 2012

Moxifloxacin is a broad-spectrum antibacterial 8-methoxy-fluoroquinolone. In order to evaluate the pharmacokinetic properties of moxifloxacin in mouse plasma and brain tissue, we developed a high-performance liquid chromatography (HPLC) method. This study was based on single-drug delivery, intravenously dosed in a central listeriosis murine model. The method employed a reversed-phase Lichrospher RP-18 with a precolumn (250×4.6 mm) and a mobile phase composed of a mixture of acetonitrile, methanol, and citric buffer (pH=3.5) with sodium dodecyl sulfate and tetrabutylammonium bromide. Fluorescence detection was performed at an excitation wavelength of 290 nm and an emission wavelength of 550 nm. The relative standard deviation of intra- and inter-day assays was <10%. This validated method led to a short retention time (8.0 min) for moxifloxacin. The standard curves were linear from 5–250 μg/L in plasma and from 0.1–2.5 μg/g of brain tissue. The limits of quantification were 5 μg/L in plasma and 0.1 μg/g in brain tissue. The method enabled the detection of systemic antimicrobial in plasma and in CNS inListeria-infected mice. Injected moxifloxacin passed through the encephalic barrier within a 30 to 60 min after injection time frame. Moxifloxacin pharmacokinetics are modeled in an infected model compared to control mice.
Dung Beetles (Coleoptera: Scarabaeinae) Attracted toLagothrix lagotricha(Humboldt) andAlouatta seniculus(Linnaeus) (Primates: Atelidae) Dung in a Colombian Amazon Forest
Authors: Noriega Jorge Ari
Published: March 2012

Dung beetles are among the most important insects in the Neotropics. Some species use a wide range of food sources, whereas other species are highly specialized. This study compares the use of two-primate excrement by an assemblage of dung beetles in a tropical forest in Colombia. Dung ofLagothrix lagotrichaandAlouatta seniculuswas used to attract beetles. A total of 32 species (47.7% of the species recorded for the area) were found on the two types of excrement studied, demonstrating that primate excrement is an important resource. The niche overlap between both feces is 27.03%, which indicates a high degree of resource specialization. Although these two primate species are found in the same areas, their diets vary greatly to permit a high degree of differentiation in beetle species. A study that includes dung of others primates would create a more complete panorama of resource overlap in the assemblage.
Robust H∞ Filtering of 2D Roesser Discrete Systems: A Polynomial Approach
Authors: El-Kasri Chakir , Hmamed Abdelaziz , Alvarez Teresa , Tadeo Fernando
Published: March 2012

The problem of robust H∞ filtering is investigated for the class of uncertain two‐dimensional (2D) discrete systems described by a Roesser state‐space model. The main contribution is a systematic procedure for generating conditions for the existence of a 2D discrete filter such that, for all admissible uncertainties, the error system is asymptotically stable, and the H∞ norm of the transfer function from the noise signal to the estimation error is below a prespecified level. These conditions are expressed as parameter‐dependent linear matrix inequalities. Using homogeneous polynomially parameter‐dependent filters of arbitrary degree on the uncertain parameters, the proposed method extends previous results in the quadratic framework and the linearly parameter‐dependent framework, thus reducing its conservatism. Performance of the proposed method, in comparison with that of existing methods, is illustrated by two examples.
Antibacterial Properties of Dental Luting Agents: Potential to Hinder the Development of Secondary Caries
Authors: Unosson Erik , Cai Yanling , Jiang Xiyuan , Lööf Jesper , Welch Ken , Engqvist Håkan
Published: March 2012

A modified direct contact test was used to evaluate the antibacterial properties of four commercially available dental luting agents (RelyX Unicem, Ketac Cem, Ceramir Crown & Bridge and Harvard Cement) and two reference materials (glass-ionomer cement and calcium aluminate cement) compared to a negative-control material (PMMA).Streptococcus mutansbacteria were placed in direct contact with specimens that had been aged for 10 min, 1 day, and 7 days, in order to test the antibacterial properties of the materials. A metabolic assay containing resazurin was used to quantify the amount of viable bacteria remaining after the direct contact tests. The effects of pH and fluoride on bacteria proliferation were also evaluated. Strongest antibacterial properties were found for calcium aluminate cement, followed by Ceramir Crown & Bridge and RelyX Unicem. Ketac Cem, Harvard Cement, and the reference glass-ionomer cement showed bacteria content either higher than or not significantly different from the PMMA control in all instances. pH levels below 6.3 and above 9.0 were found to have negative effects on bacterial proliferation. No correlation between either acidic materials or fluoride release and antibacterial properties could be seen; rather, basic materials showed stronger antibacterial properties.
Nanostructural, Chemical, and Mechanical Features of nc-Si:H Films Prepared by PECVD
Authors: Son Jong-Ick , Nam Hee-Jong , Cho Nam-Hee
Published: March 2012

This study examined the effects of film thickness on the nanostructural, chemical, and mechanical features of nc-Si:H films deposited by plasma-enhanced chemical vapor deposition. SiH4and H2were used as the source gases, and the deposition time was varied from 10 to 360 min. The mean nanocrystallites size in the Si films increased from~6 to~8 nm with increasing film thickness from 85 to 4150 nm. Moreover, the nanocrystallite concentration and elastic modulus increased from~7.5 to~45% and from 135 to 147 Gpa, respectively. In the 4150 nm thick film, the relative volume fraction of Si nanocrystallites and relative fraction of Si–H bonds in the films were approximately~45% and~74.5%, respectively.
Observations on the Morphology, Pollination and Cultivation of Coco de Mer (Lodoicea maldivica (J F Gmel.) Pers., Palmae)
Authors: Blackmore Stephen , Chin See-Chung , Chong Seng Lindsay , Christie Frieda , Inches Fiona , Winda Utami Putri , Watherston Neil , Wortley Alexandra H.
Published: March 2012

We present a range of observations on the reproductive morphology, pollination biology and cultivation of Lodoicea maldivica (coco de mer), an endangered species with great ecological, economic and cultural importance. We review the history of study of this charismatic species. Morphological studies of the male inflorescence indicate its importance as a year-round food source to the Seychelles fauna. In situ observations suggest a number of potential biotic and abiotic pollination mechanisms including bees, flies, slugs, and geckos; trigonid bees are identified as the most likely potential natural pollinator. We outline a successful programme for ex situ pollination, germination, and cultivation of the coco de mer, highlighting the importance of temperature, humidity and light levels as well as maintaining an undisturbed environment. In combination with continued protection and monitoring, this advice may aid the future in situ and ex situ conservation of the coco de mer.
The Biological Significance of Evolution in Autoimmune Phenomena
Authors: Cañas Carlos A. , Cañas Felipe
Published: March 2012

It is an inherent part of living to be in constant modification, which are due to answers resulting from environmental changes. The different systems make adaptations based on natural selection. With respect to the immune system of mammals, these changes have a lot to do with the interactions that occur continuously with other living species, especially microorganisms. The immune system is primarily designed to defend from germs and this response triggers inflammatory reactions which must be regulated in order not to generate damage to healthy tissue. The regulatory processes were added over time to prevent such damage. Through evolution the species have stored “an immunological experience,” which provides information that is important for developing effective responses in the future. The human species, which is at a high level of evolutionary immunological accumulation, have multiple immune defense strategies which, in turn, are highly regulated. Imbalances in these can result in autoimmunity.
A Hybrid Multiobjective Genetic Algorithm for Robust Resource‐Constrained Project Scheduling with Stochastic Durations
Authors: Xiong Jian , Chen Ying-wu , Yang Ke-wei , Zhao Qing-song , Xing Li-ning
Published: March 2012

We study resource‐constrained project scheduling problems with
perturbation on activity durations. With the consideration of robustness
and stability of a schedule, we model the problem as a multiobjective optimization
problem. Three objectives—makespan minimization, robustness
maximization, and stability maximization—are simultaneously considered. We
propose a hybrid multiobjective evolutionary algorithm (H‐MOEA) to solve
this problem. In the process of the H‐MOEA, the heuristic information is
extracted periodically from the obtained nondominated solutions, and a local
search procedure based on the accumulated information is incorporated. The
results obtained from the computational study show that the proposed approach
is feasible and effective for the resource‐constrained project scheduling
problems with stochastic durations.
Impulsive Cluster Anticonsensus of Discrete Multiagent Linear Dynamic Systems
Authors: Zhang Liping , Jiang Haibo
Published: March 2012

Cluster anticonsensus is another important type consensus of multiagent systems. In this paper,
we investigate the problem of impulsive cluster anticonsensus of discrete multiagent linear dynamic
systems. Firstly, an impulsive protocol is designed to achieve the cluster anticonsensus. Then sufficient
conditions are given to guarantee the cluster anticonsensus of the discrete multiagent linear dynamic
system based on the Q‐theory. Numerical simulation shows the effectiveness of our theoretical results.
Fabrication of Al-Doped TiO2Visible-Light Photocatalyst for Low-Concentration Mercury Removal
Authors: Tsai Cheng-Yen , Kuo Tien-Ho , Hsi Hsing-Cheng
Published: March 2012

High-quality Al-doped TiO2visible-light photocatalyst was prepared via a single-step direct combination of vaporized Ti, Al, and O2using a 6 kW thermal plasma system. Results showed that the formed Al-doped TiO2nanoparticles were a mixture of anatase and rutile phase and had a size between 10 and 105 nm. The absorption spectra of the nanoparticles shifted towards the visible light regions, depending on the Al2O3addition. Ti4+and Ti3+coexisted in the synthesized Al-doped TiO2; the Ti3+concentration, however, increased with increasing Al2O3addition due to Al/Ti substitution that caused the occurrence of oxygen vacancy. Hg0breakthrough tests revealed that the nanoparticles had an appreciable Hg0removal under visible-light irradiation. Nevertheless, moisture reduced Hg removal by the nanoparticles, especially when visible-light irradiation was applied, suggesting that the competitive adsorption between H2O and Hg species on the active sites of TiO2surface occurred.