Poly(styrene-co-acrylonitrile)/montmorillonite organoclay mixtures: a model system for ABS nanocomposites

Dispersion of clay particles in acrylonitrile-butadiene-styrene (ABS) and styrene-acrylonitrile copolymer (SAN) nanocomposites with montmorillonite (MMT) have been compared to assess whether ABS/MMT nanocomposite behavior can be adequately modeled using the simpler SAN/MMT system. Electron microscopy photomicrographs show that clay particles in ABS/MMT composites reside in the SAN matrix phase and accumulate at the rubber particle surfaces. In mixtures of four organoclays with the two polymers, WAXS (wide angle X-ray scattering) peak height and shift in gallery height was the same for a given organoclay. Aspect ratios determined through image analysis were also the same in each polymer. Modulus enhancement as measured by an exfoliation efficiency index showed the same patterns for each organoclay in the two matrices, but the ABS/MMT composites had consistently lower efficiencies than in SAN/MMT composites. This trend is expected to be due to the variations in orientation of clay particles in ABS/MMT composites at the rubber particle surface. In summary, SAN/MMT composites represent a good model system for ABS/MMT.     

Tackling representation,annotation and classification challenges for temporal knowledge base population

Temporal Information Extraction (TIE) plays an important role in many natural language processing and database applications. Temporal slot filling (TSF) is a new and ambitious TIE task prepared for the knowledge base population (KBP2011) track of NIST Text Analysis Conference. TSF requires systems to discover temporally bound facts about entities and their attributes in order to populate a structured knowledge base. In this paper, we will provide an overview of the unique challenges of this new task and our novel approaches to address these challenges. We present challenges from three perspectives: (1) Temporal information representation: We will review the relevant linguistic semantic theories of temporal information and their limitations, motivating the need to develop a new (4-tuple) representation framework for the task. (2) Annotation acquisition: The lack of substantial labeled training data for supervised learning is a limiting factor in the design of TSF systems. Our work examines the use of multi-class logistic regression methods to improve the labeling quality of training data obtained by distant supervision. (3) Temporal information classification: Another key challenge lies in capturing relations between salient text elements separated by a long context. We develop two approaches for temporal classification and combine them through cross-document aggregation: a flat approach that uses lexical context and shallow dependency features and a structured approach that captures long syntactic contexts by using a dependency path kernel tailored for this task. Experimental results demonstrated that our annotation enhancement approach dramatically increased the speed of the training procedure (by almost 100 times), and that the flat and structured classification approaches were complementary, together yielding a state-of-the-art TSF system.     

Combined chemical (ozone) and biological treatment of polychlorinated biphenyls (PCBs) adsorbed to sediments

Laboratory experiments were conducted to test the feasibility of ozone sparging to oxidize PCBs in sediments, and to determine the organic acid content and biodegradability of the oxidation products. Two PCBs were tested; 2‐,2′‐dichlorobiphenyl (DCB) and 2‐,3‐,4‐,2′‐,3′‐,4′‐hexachlorobiphenyl (HCB). DCB and HCB were allowed to adsorb onto solids in slurries of pure kaolinite and river sediments containing 2% native organic matter (NOM). Ozone was sparged through the slurries while concentrations of PCBs and Cl^?, and chemical oxygen demand (COD) were measured with time. Gas chromatography/mass spectrometry (GC/MS) was used to identify the organic acids produced from the reaction of ozone with DCB and HCB. After sparging, the liquid was placed in bioreactors with inoculum from a domestic wastewater treatment plant and nutrients. Ozone sparging in the kaolinite slurries removed 94% of HCB and 97% of DCB in 30 days. In contrast, 55 days were required to achieve the same PCB removal in river sediment slurries. Ozone doses per g of DCB and HCB in kaolinite were 19 g and 30 g, respectively. Doses were 13–14 times greater in river sediments. Formic and oxalic acids were ozonation products of both PCBs. Specific ozonation products of DCB and HCB were 2‐hydroxybenzoic acid and 2,3,4‐trihydroxybenzoic acid, respectively. The results show that ozone caused ring cleavage of PCBs and stoichiometric replacement of Cl with OH groups. Over 93% of the soluble COD from ozone sparging was biodegraded within 20–26 days in the bioreactors. © 2002 Society of Chemical Industry     

Polymers from 2,5-difluoroterephthalic acid II. Poly(arylene ether)s containing pendant benzoyl groups

Poly(arylene ether)s (9) containing pendant benzoyl groups were prepared by the aromatic substitution reaction of 2,5-difluoro-4-benzoylbenzophenone (7) with bisphenol (8) in the presence of potassium carbonate in N,N-dimethylacetamide. The polycondensation proceeded smoothly at 170°C and produced the desired poly(arylene ether)s with inherent viscosities up to 0.79 dl/g. The polymers were quite soluble in common organic solvents and can be processed into uniform films from solutions. The thermogravimetry of the polymers showed excellent thermal stability, 10% weight losses above 450°C in nitrogen atmosphere. The glass-transition temperatures of the polymers were 138–158°C.     

Multichannel digital phase sensitive detection using a field programmable gate array development platform

This paper describes the development and performance of digital phase sensitive detectors (PSDs) based on a field programmable gate array (FPGA) logic device. A FPGA development system combined with a custom analog data acquisition board provides a powerful platform for the development of digital signal processing systems. Conventional performance metrics for digital PSDs are determined by the analog front-end devices and do not represent improvements to the PSD itself. FPGAs offer a scalable platform on which digital PSDs can be implemented with enhanced capabilities including simultaneous demodulation of multiple independent analog signals at multiple frequencies with arbitrary demodulation functions. Circuits for providing dynamic frequency tracking and ultrafine (<0.001 degrees ) phase resolution are presented.     

Inferring gender from name phonology.

English male and female names have different phonological properties. This article examines 3 questions about this phenomenon: How informative is phonology about gender? Have English speakers learned this information? Does this knowledge affect name usage? Results from a connectionist model indicate that English phonology predicts name gender quite well. Experiments found that English speakers have learned these cues. For example, names were classified as male or female more quickly and accurately when they had phonologically typical properties. Further studies demonstrated that the evolution of names in this century was affected by how male or female they sounded and that knowledge of phonological cues to gender influences the perception and structure of brand names. Implications for stereotyping, individual differences, and language research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of calcium peroxide to provide oxygen for contaminant biodegradation in a saturated soil.

Laboratory studies were conducted in solid-phase reactors on a silty loam contaminated with bis-(2-ethylhexyl) phthalate (BEHP) to determine the conditions under which calcium peroxide (CaO(2)) would promote the aerobic bioremediation of water-saturated soil. Closed 500 ml solid-phase reactors were operated to determine whether CaO(2) stimulated the biodegradation of BEHP in saturated soil. Ex situ bioremediation conditions were then simulated by mixing water-saturated soil for 6 h before placing the soil in three vented, 2 l solid-phase reactors for 50 days. Biodegradation of BEHP was quantified using four different measurements of microbial activity: (1) oxygen concentrations in the reactor gas; (2) bacterial colony-forming units (CFU); (3) fungal CFU; and (4) 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride dehydrogenase activity (INT-DHA). CaO(2) released molecular O(2), which retarded dewatering but substantially enhanced BEHP biodegradation. After 20 days, BEHP in the amended reactor was reduced from 20.3 to roughly 5 g kg(-1) vs. 15 g kg(-1) in the reactor without CaO(2). Bacterial growth was favored over fungal growth at elevated moisture and BEHP levels.     

Temperature desensitisation of delay in optical fibres for sensor applications

We demonstrate a significant reduction in delay sensitivity against temperature in optical fibres, using a novel tight jacketed fibre structure. This technique has the cabability of producing fibre in which the optical delay is insensitive to temperature. This has potential in the field of sensors and fibre devices.     

Gain measurements of Fabry-Pe/spl acute/rot semiconductor lasers using a nonlinear least-squares fitting method

A method for the measurement of the gain-reflectance product of Fabry-Pe/spl acute/rot (F-P) semiconductor lasers is proposed and compared to other techniques. The method is based on a nonlinear, least-squares fitting of the F-P modes to an Airy function. A separate fitting is performed over each mode, as measured with an optical spectrum analyzer (OSA), so that the gain-reflectance parameters are extracted. The influence of the OSAs response function is considered by convolution of the Airy function with the response function of the OSA. By comparing with the Hakki-Paoli method, the mode sum/min method, and the Fourier series expansion method, we find that the nonlinear fitting method is the least sensitive to noise. However, owing to a broadening of the F-P modes of the semiconductor laser, the mode sum/min method combined with a deconvolution technique gives the least underestimated gain above threshold.     

Source Transformation for Concurrency Analysis

Concurrent programming poses a unique set of problems for quality assurance. These difficulties include the complexities of deadlock, livelock and divergence, which can be extremely difficult to detect and debug. A variety of tools have been developed to assist designers and developers of concurrent applications. Some of these tools, such as VeriSoft, are specific to particular implementation languages, such as C++.The Java Remote Method Invocation (Java RMI) package facilitates the implementation of concurrent applications, including those where processes reside on different hosts and communicate over networks. Unfortunately, it does not relieve the developer from the potential pitfalls of controlling concurrent access to remote objects, and may, in fact, make concurrency problems even more difficult to find.This paper presents an approach that allows the VeriSoft state exploration system to be used to analyze Java RMI programs for deadlock, livelock, divergence, and assertion violations. The system works by transforming Java RMI programs into C++ programs where Java syntax, structure, concurrency and memory management are replaced by C++ equivalents and Java RMI communication has been transformed to VeriSoft C++ inter-process communication. We present the details of this transformation and discuss preliminary results for a number of small examples.