X-ray reflectivity studies on DLC films deposited by microwave ECR CVD: Effect of substrate bias

Diamond like carbon (DLC) films were deposited at room temperature on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) process using plasma of methane diluted with argon gas. During deposition, dc self bias (− 25 V to − 200 V) on substrate was varied by application of RF power to the substrate. The influence of substrate bias on density of the deposited films was studied by X-ray reflectivity (XRR). The results from these measurements are further correlated with the results from UV and visible Raman spectroscopy. DLC film is modeled as a structure having three different layers such as low density surface, bulk and interface with the substrate. This three-layer model is used to fit the measured XRR data to evaluate the surface, interface and interlayer roughness, thickness and density of these films. The surface roughness obtained from XRR is correlated with the results from Atomic Force Microscopy (AFM) measurements. The observed results are explained based on the subplantation model for DLC film growth.     

Phase behavior and detergency study of lauryl alcohol ethoxylates with high ethylene oxide content

Nonionic surfactants such as fatty alcohol ethoxylates have been extensively used in many detergent applications, because of their high calcium ion tolerance, low critical micelle concentrations, and mildness. Although ethoxylates containing high ethylene oxide (EO) content (EO>10 moles) score higher than their low-FO counterparts on many of these desired properties, they have not been studied adequately in the context of detergency, primarily because their cloud points (CP) are higher than normal wash temperatures, typically >100°C, and thus cannot be measured. However, once the CP are manipulated appropriately using salting-out electrolytes, these surfactants can offer certain distinct advantages in terms of their molecular and phase structure. We have studied the phase structure and clouding behavior of tetradecyl ethylene-oxide mono dodecyl alcohol (C₁₂EO₁₄), a broad-range ethoxylate, as a function of the concentrations of various electrolytes. We found that, beyond a certain critical concentration, the CP decreases monotonically with increasing salt concentration. For sodium salts of various anions, the CP depression is inversely proportional to the lyotropic number of the anion. Similarly, for chloride salts of various cations, CP depression is inversely proporitional to the lyotropic number of the cation However, the effect of changing anion is stronger than that of changing cation. A micrograph of a water penetration scan at room temperature indicates the presence of isotropic L₁; hexagonal, isotropic L₂; and solid phases with increasing surfactant concentration. As is the case with low-FO nonionics, a maximum in detergency of model oily soils was found to correlate well with the minimum in oil/water interfacial tension when plotted vs. temperature. Ross Miles foam height increases with increasing concentration of salt.     

Synthesis of nanocrystalline CeAlO3 by solution-combustion route

CeAlO₃ was synthesised by a modified solution-combustion route using a mixture of urea and glycine as fuel. A trivalent oxidation state of cerium was stabilised and high-quality single phase polycrystalline CeAlO₃ was obtained by optimising the ratio of fuels. The transmission electron micrography and powder X-ray diffraction investigations showed that the particles were nanocrystalline in nature. Rietveld refinement confirmed the space group of the structure to be I4/mcm$I4/mcm$ with lattice parameters a=5.3278(1)$a=5.3278(1)$ Å, c=7.5717(3)$c=7.5717(3)$ Å. Magnetisation measurements indicated that the sample was paramagnetic up to 2 K. The susceptibility data fitted the Curie–Weiss model in the temperature range 100–300 K with _θp=−40${\theta }_p=-40$ K. The value of _μeff=2.2_μB${\mu }_{\text{eff}}=2.2{\mu }_B$ was close to that expected for a Ce³⁺ ion. The magnetic properties were comparable to that reported for single crystals indicating the high quality of CeAlO₃ prepared in the present work. The semiconducting band gap as estimated from UV–visible spectroscopy was 3.26 eV.     

Role of size scale of ZnO nanoparticles and microparticles on toxicity toward bacteria and osteoblast cancer cells

The specific role of size scale, surface capping, and aspect ratio of zinc oxide (ZnO) particles on toxicity toward prokaryotic and eukaryotic cells was investigated. ZnO nano and microparticles of controlled size and morphology were synthesized by wet chemical methods. Cytotoxicity toward mammalian cells was studied using a human osteoblast cancer cell line and antibacterial activity using Gram-negative bacteria (Escherichia coli) as well as using Gram-positive bacteria (Staphylococcus aureus). Scanning electron microscopy (SEM) was conducted to characterize any visual features of the biocidal action of ZnO. We observed that antibacterial activity increased with reduction in particle size. Toxicity toward the human cancer cell line was considerably higher than previously observed by other researchers on the corresponding primary cells, suggesting selective toxicity of the ZnO to cancer cells. Surface capping was also found to profoundly influence the toxicity of ZnO nanoparticles toward the cancer cell line, with the toxicity of starch-capped ZnO being the lowest. Our results are found to be consistent with a membrane-related mechanism for nanoparticle toxicity toward microbes.     

Fibers from soybean protein and poly(vinyl alcohol)

Bicomponent fibers were wet‐spun from soybean protein and poly(vinyl alcohol). The protein core of the spun bicomponent fiber was brittle and showed a high frequency of core breakage upon drawing. Our effort was then to study the soybean protein solution, with the aim of trying to understand the cause for fiber brittleness and to determine the optimum solution conditions for fiber spinning. The effects of alkali, urea, and sodium sulfite on the viscosity of the soybean protein solution were examined. The hydrolytic stability of the soybean protein solution was examined at various pH values at two temperatures (room temperature and 60°C). Both the viscosity and gel electrophoresis were used for this purpose. The degradation of the soybean protein and the existing microgels in the protein spinning solution were thought to be the causes for the poor fiber drawability. Extent of protein denaturation will also effect the fiber drawability. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 11–19, 1999     

Suspicious human activity recognition: a review

Suspicious human activity recognition from surveillance video is an active research area of image processing and computer vision. Through the visual surveillance, human activities can be monitored in sensitive and public areas such as bus stations, railway stations, airports, banks, shopping malls, school and colleges, parking lots, roads, etc. to prevent terrorism, theft, accidents and illegal parking, vandalism, fighting, chain snatching, crime and other suspicious activities. It is very difficult to watch public places continuously, therefore an intelligent video surveillance is required that can monitor the human activities in real-time and categorize them as usual and unusual activities; and can generate an alert. Recent decade witnessed a good number of publications in the field of visual surveillance to recognize the abnormal activities. Furthermore, a few surveys can be seen in the literature for the different abnormal activities recognition; but none of them have addressed different abnormal activities in a review. In this paper, we present the state-of-the-art which demonstrates the overall progress of suspicious activity recognition from the surveillance videos in the last decade. We include a brief introduction of the suspicious human activity recognition with its issues and challenges. This paper consists of six abnormal activities such as abandoned object detection, theft detection, fall detection, accidents and illegal parking detection on road, violence activity detection, and fire detection. In general, we have discussed all the steps those have been followed to recognize the human activity from the surveillance videos in the literature; such as foreground object extraction, object detection based on tracking or non-tracking methods, feature extraction, classification; activity analysis and recognition. The objective of this paper is to provide the literature review of six different suspicious activity recognition systems with its general framework to the researchers of this field.     

Mechanical properties of sisal fibre at elevated temperatures

Sisal fibres extracted from the leaves of Agava sisalana plants 3, 5, 7 and 9 years old were tested at different temperatures for tensile strength, elongation, toughness and modulus. The tensile strength, modulus and toughness values of sisal fibre decreased with increase in temperature. The effect of plant age on tensile strength, tensile modulus and toughness of sisal fibre became very much less at 100 °C as compared to 30 °C. Fractured fibres were observed by using a scanning electron microscope. The ends of fibres fractured at elevated temperature showed a failure similar to that of inorganic fibres. Elongation values at all temperatures increased with age. Elongated capillaries were observed in fibres fractured at 80 and 100 °C, due to the removal of moisture and volatiles originally present in the fibres. The fibrils are clearly observed in the form of hollow cylinders. Fractured surfaces are composed of brittle as well as ductile phases. The ductile portion increased with the increase of temperature.     

Delivery of drug macromolecules from thermally responsive gel implants to the posterior eye

Therapeutic modalities for posterior-eye diseases involve mostly interventions through the anterior eye, which are difficult for physicians and patients alike. Currently, sustained drug delivery to the posterior eye is gaining importance. A study for sustained delivery of an anti-VEGF agent to the posterior eye from an implant, made of poly(N-isopropylacrylamide) (NIPAM) and placed episclerally, is presented. The thermally sensitive gel is modelled as a poroelastic material with a phase transition characterized by a lower critical solution temperature (LCST). The study utilizes compartments for various eye tissues, with individual compartments considered to be completely mixed and drug transport between compartments occurring by one-dimensional diffusion.     

Development of a New Airborne Humidigraph System

The hygroscopic behavior of atmospheric aerosols complicates modeling and measurements of aerosol properties adding significant uncertainty to our best estimates of the direct effect aerosols exert on the radiative balance of the atmosphere. Airborne measurements of aerosol hygroscopicity are particularly challenging but critically needed. This motivated the development of a new system designed to measure the dependence of the aerosol light scattering coefficient (σ _sp) on relative humidity (RH), known as f(RH), in real-time on an aerial platform.

The new instrument has several advantages over existing systems. It consists of three integrating nephelometers and humidity conditioners for simultaneous measurement of the σ _sp at three different RHs. The humidity is directly controlled in exchanger cells without significant temperature disturbances and without particle dilution, heating, or loss of volatile compounds. The single-wavelength nephelometers are illuminated by LED-based light sources thereby minimizing heating of the sample stream. The flexible design of the RH conditioners, consisting of a number of specially designed exchanger cells (driers or humidifiers), enables us to measure f(RH) under hydration or dehydration conditions (always starting with the aerosol in a known state) with a simple system reconfiguration. These exchanger cells have been characterized for losses of particles using latex spheres and laboratory generated ammonium sulfate aerosols. The performance of this instrument has been assessed aboard DOE's G-1 research aircraft during test flights over California, Oregon, and Washington.

Copyright 2013 American Association for Aerosol Research