Influence of Slurry Characteristics on Porosity and Mechanical Properties of Alumina Foams

Alumina foams with porosity ranging between 50% and 92% were fabricated by foaming followed by coagulation of ovalbumin based aqueous slurries. Different combinations of ovalbumin–water mix and alumina loading provided a means to vary slurry viscosity over a wide range. Slurry viscosity influenced the foaming behavior leading to variation in microstructure and mechanical properties of alumina foams. Controlling the slurry viscosity resulted in controlled the total porosity, microstructures and mechanical properties. Mechanical properties were correlated with different micro-mechanical models. Both microstructure and mechanical properties agreed well as closed cell alumina foam due to presence of low percent area of interconnections.     

Temperature-dependent short-channel parameters of FinFETs

The remarkable development and continual proliferation of research in the nanotechnology field have led to improvement in the efficiency of elementary devices. To improve their performance, the parameters of such devices can be scaled down while optimizing their characteristics. However, this simultaneously results in degraded switching characteristics and the appearance of short-channel effects. Multigate-based fin-shaped field-effect transistors (FinFETs) represent a new option to address all these problems. However, thermal failure of FinFET devices under nominal operating conditions is an important issue in the design and implementation of high-speed semiconductor devices. It is also seen that bulk FinFETs exhibit better thermal performance compared with silicon-on-insulator FinFETs. In the work presented herein, various FinFET characteristics including the subthreshold swing, drain-induced barrier lowering, threshold voltage, and drain current were investigated as functions of temperature. The (effective) channel length is larger than the physical gate length (in off-state) due to the undoped underlap regions. This paper also discusses the effects of drain, source, and gate overlap.     

Determination of Ni and Zn in an Oil Matrix using Schiff Base‐Assisted Extraction Followed by a Flame Atomic Absorption Spectrometer: A Simple Strategy to Determine Ni and Zn

In the present work, a new and simple Schiff base‐assisted extraction strategy for Ni and Zn from an edible oil matrix with subsequent determination using a flame atomic absorption spectrometer was suggested. According to the green approach, laborious sample‐pretreatment procedures were eliminated via complexation of the analytes with N,N′‐bis(4‐methoxysalycylidene)‐2‐hydroxy‐1,3‐propanediamine (4MSHP) and transferred from the oil phase to the aqueous phase. The complexation properties of 4MSHP, Ni, and Zn were investigated using UV–vis spectrophotometry. The experimental conditions that affect the extraction efficiency were optimized using central composite design. The optimum conditions for the extraction of Ni and Zn were as follows: a volume to oil mass ratio of 0.83 to 1.31 mL g^?1 of 4MSHP solution; 62.3‐ and 50.6‐min, stirring time; 27.3 and 31.1 °C, temperature, respectively. The detection limits (3s_bm^?1) were 0.41 μg g^?1 for Ni and 0.16 μg g^?1 for Zn. Validation of the suggested work was performed by the analysis of organometallic standard‐doped n‐hexane solutions as certified reference materials under the optimum experimental conditions. The recovery percentages were warranted the accuracy and found as 98.2 ± 1.8% for Ni and 99.8 ± 1.2% for Zn. In addition, relative SD values were below 5% for both the analytes. The Student's t‐test showed that there was no significant difference between the found and doped amount of analytes at 95% confidence level. The features such as the detection technique, cheapness, eco‐friendly solvent usage, and practicality were better compared to the literature.     

Phosphorylated cardanol prepolymer grafted guayule natural rubber: an advantageous green natural rubber

Natural rubber (HNR), produced from Hevea Brasiliensis, is being considered as the major source of 99.9% 1,4-cis-polyisoprene. Till date, this grade of natural rubber is not manufactured synthetically even using sophisticated solution polymerization techniques and utilizing the most advanced catalyst systems. Rubber industries have been continuously thriving for an alternative as well as an additional source of natural rubber to compensate for the reduction in production of Hevea natural rubber and to reduce the consumption of petroleum-based rubbers. The present study deals with chemical grafting of phosphorylated cardanol prepolymer (PCP) onto the main chain of guayule natural rubber (GNR), which could impart inherent multifunctional characteristics to the rubber. The grafting of PCP onto GNR was carried out successively using benzoyl peroxide as a free radical initiator in the solution stage and the grafting parameters have been optimized through the Taguchi method using grafting efficiency and percent grafting. Grafting of PCP onto GNR (PCP-g-GNR) was confirmed through UV–Visible, FTIR, NMR and GPC analysis. Thermal behavior of PCP-g-GNR indicates a significant increase in thermo-oxidative stability and it also displays a slight depression of glass transition temperature as compared to GNR. The viscoelastic characteristics of GNR also alter and cure characteristic improves drastically in giving rise to improved processability after grafting of the PCP. The unfilled PCP-g-GNR vulcanizates show approximately similar physico-mechanical properties with 5 phr processing oil as plasticized GNR vulcanizates. Therefore, PCP-g-GNR can be used in rubber industries as gum rubber materials as it reduces the usage of processing aids significantly.     

Circular footings resting on geotextile-reinforced sand bed

The note pertains to an experimental study made on circular footings resting on semi-infinite layer of sand reinforced with geotextiles. Using the concept of homogenization of such soils, both analytical and numerical analyses have also been conducted to predict the load-settlement behavior and compared with experimental observations. The study highlights the effect of the footing size, number of reinforcing layers, reinforcement placement pattern and bond length and the relative density of the soil on the load-settlement characteristics of the footings.     

Nanostructured organic-inorganic photodiodes with high rectification ratio

High quality organic-inorganic heterojunction photodiodes based on nanostructured copper (II) phthalocyanine (CuPc) and intrinsic zinc oxide (i-ZnO) have been fabricated. The i-ZnO thin films/layers were grown by RF magnetron sputtering on clean indium tin oxide (ITO) coated glass substrates. These films have been characterized by optical absorption and field emission scanning electron microscopy (FESEM). CuPc thin films deposited at room temperature on i-ZnO have exhibited a change in their surface morphology with the post-deposition annealing temperature under normal atmosphere. The electrical dark conductivity and the photoconductivity of ITO/i-ZnO/CuPc/Au sandwich structures have been measured under various photoexcitation intensities using a xenon light source. The devices have shown excellent reproducibility of their electrical characteristics and high rectification ratios. The highest rectification ratio is nearly 831 calculated above the threshold voltage at room temperature for the sample annealed at 250?°C (i.e.?Pc 250). The effects of the annealing temperature of CuPc on the surface morphology, rectification ratio, and optical properties have been discussed.     

Ingestible capsule for impedance and pH monitoring in the esophagus

Twenty-four-hour ambulatory pH monitoring is an essential tool for diagnosing gastroesophageal reflux disease (GERD). Simultaneous impedance and pH monitoring of the esophagus improves the detection and characterization of GERD. Conventional catheter-based monitoring systems are uncomfortable and interfere with the normal activity of the patient. To overcome these disadvantages, different wireless esophageal monitoring systems have been proposed. A capsule containing sensors for impedance and pH monitoring with wireless communication capabilities is presented. A low cost miniature microcontroller was utilized for interfacing between the sensors and a wireless transmitter. The microcontroller program allowed efficient management of the electric power provided by a 3-V battery. Magnetic holding is proposed as an alternative to surgical affixation of the monitoring capsule. Permanent neodymium magnets separated by 27 cm successfully held the capsule in a test tube. Experimental results demonstrated that friction force can aid magnetic holding to overcome peristalsis. The proposed design efficiently detected acid and nonacid reflux. More research regarding the holding method and capsule packaging are necessary to optimize the mechanical performance of the proposed design in order to facilitate clinical testing on human subjects.     

Nanostructured Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZrO<Subscript>2</Subscript> composite synthesized by sol–gel technique: powder processing and microstructure

Al₂O₃–ZrO₂ composite gel powder was prepared by sol–gel route. The gel precursor compositions were preferred to achieve yield of 5–15 mol% zirconia after calcination of respective powders. The precursor gel was characterized by Differential Thermal Analysis (DTA)/Thermo Gravimetric (TG), IR and X-ray Diffraction study (XRD). The analysis reveal the gel contained pseudoboehmite and amorphous Zr(OH)₄, which was decomposed in three and two stages respectively. The phase transformation of alumina during calcination followed the sequence of pseudoboehmite → bayerite → boehmite → γ-Al₂O₃ → θ-Al₂O₃ → α-Al₂O₃, while that of ZrO₂ follows amorphous ZrO₂ → t-ZrO₂ → (t + m) ZrO₂. Fourier Transform Infrared Spectroscopy (FTIR) studies showed that the number of M–OH and M–O bond increases with zirconia due to a change in the cationic charge of the composite powder. Transmission Electron Microscopy (TEM) photograph of calcined powder exhibited the presence of dispersed as well as agglomerated nano sized spherical particles. SEM and Electron Probe Microscope Analysis (EPMA) confirmed the near uniform distribution of zirconia particles in the alumina matrix.     

Preparation and Characterization of Ni-Ferrite Coating on Carbon Steel Coupons

1.IntroductionTheinteractionofhightemperaturewaterwithcarbonsteel(CS)structuralsurfacesundertheprimaryheattransport(PHT)chemistryconditionsresultsintheformationofaprotectivemagnetitefilmwhichhasabilayerstructure.TheoxidelayerclosetometalgrowsintoitduetoO2-movementandoxi-dationofiron.Theouterlayerisformedbyprecipita-tionofFe3O4duetosupersaturationofthecirculat-ingcoolallt.Therelativemagnitudeofthethicknessofthetwolayersandtheirvariationwithtimeareaffectedbymanyfactors.Theporosityofthefilmgi…