Cold compaction and sintering of ultrahigh-molecular-weight polyethylene containing a segregated iron network

To improve the powder processing behavior of ultrahigh-molecular-weight polyethylene, a conductive iron filler was distributed within the polymer in a segregated network. The filler level was kept at a minimum of 10 volume percent, which was sufficient to coat completely all the polymer particle surfaces. This filler level was low enough to avoid modifying the resin properties to a significant extent. Compaction of these filled samples showed a slower densification, under pressure, similar level of final densification at 80% densification parameter, and a doubling of plateau pressure value to 200 MPa in comparison with the unfilled polymer. The filler was found to reduce drastically the postcompaction relaxation time from 24 h to 6 h. The magnitude of the axial (compaction direction) relaxation was unchanged, but the radial relaxation was one quarter of that for the unfilled polymer. Sintering behavior showed improved densification because of lower dimensional changes during sintering resulting in 80% relative sintered density, higher than the 75% percent value for the unfilled polymer, but yielded a 20% lower sintered strength, An alternative process of rapid sintering by induction heating was explored, its feasibility demonstrated, and a recommendation is made to make powder processing of this polymer commercially attractive.     

Studies on Tamarind Kernel Polysaccharides. Part II. Fractionation and Examination of Minor Component Polysaccharides

Tamarind kernel powder has been fractionated by aqueous extraction and by complexing with copper to afford three fractions I—III. Fraction I contains sizable amounts of proteinous matter whereas fractions II and III are almost pure polysaccharides. Methylation of fraction III followed by hydrolysis produces 2,3,5-tri-O-methyl-L -arabinose (1 mole); 2,3,4-tri-O-methyl-D -xylose (1 mole); 2,3,4,6-tetra-O-methyl-D -galactose (1 mole); 2,3,6-tri-O-methyl-D -glucose (1 mole); 3,4-di-O-methyl-D -xylose (1 mole); and 2,3-di-O-methyl-D -glucose (3 moles). The structure of the polysaccharides is discussed in the light of the above results.     

Modeling the performance of molten carbonate based direct carbon fuel cell anode

A mathematical model is developed to study the performance of a molten carbonate based direct carbon fuel cell anode. The direct carbon fuel cell(DCFC) is a fuel cell which uses solid carbon as fuel and molten carbonate as electrolyte. The model assumes that the 4 electron carbon oxidation reaction is the primary reaction driving the DCFC. However, the 2 electron CO oxidation reaction and the reverse Boudouard reaction is also considered in this model. The model studies the effect of performance parameters on the performance of the DCFC. The effect of the bulk conductivity in the solid phase, the bulk conductivity in the liquid phase, carbon loading and the thickness of the anode layer on the potential and current distribution in the cell is modeled. Model results are compared with experimental data and found to compare well.     

Rheological behavior of syrups containing sugar substitutes

The rheological properties of syrups prepared using bulk sweeteners such as sorbitol and bulking agents like maltodextrin and polydextrose along with aspartame were studied. The apparent viscosity, consistency index, yield stress, and flow behavior index were determined from the shear stress versus shear rate data. The Herschel–Bulkley model was found to adequately describe the flow behavior of the syrups. The activation energy for all the syrups at different concentrations was determined from the Arrhenius equation. The yield stress, flow behavior index, and consistency index were dependent on the temperature and concentration of the syrups. The apparent viscosity increased from 8.8 to 129 mPa·s for sugar and sorbitol syrups, respectively, over the concentration range from 35 to 65%. In general, the rheological characteristic of sorbitol syrup was similar to that of sugar syrup, while syrups made with polydextrose and its mixture with maltodextrin were significantly different from those of sugar syrup.     

Enzyme-assisted extraction of volatiles from cumin (Cuminum cyminum L.) seeds

The effect of various enzymes on the extraction of the volatile oil of cumin (Cuminum cyminum L.) is reported in the present study. The oil yield, after pre-treatment of cumin seeds with cellulase, pectinase, protease and Viscozyme, was in the range 3.2–3.3% compared to 2.7% in a control sample. Profiling of the cumin oil by GC–MS showed that the total hydrocarbon content was 63.7%, 66.1% and 70.1% in control, cellulase and Viscozyme treated samples, respectively. However, there was no change in the content of cuminaldehyde, the principal flavour-impact constituent, in any of the volatile oils. The study demonstrated that enzymes facilitated the extraction of cumin oil with increase in oil yield, with little change in either flavour profile or physicochemical properties of the oil.     

Simple Notch Preparation Technique for Fracture Toughness Measurements in Partially Stabilized Zirconia

Fracture toughness is an important property of transformation-toughening materials. Since indentation techniques are not reliable, notched-beam techniques using slicing wheels on grinding machines are often used. Notching can induce residual stress as well as cracks, the effect of which cannot be completely nullified by annealing. Hence, the fracture toughness estimation methods may not yield realistic values for transformation-toughening materials. The present paper reports on a reliable technique for notch preparation which can completely exclude the detrimental effects of stress/cracking that may arise due to notching, using slicing wheels on grinding machines.     

Evaluation of size reduction on the yield and quality of celery seed oil

The effect of grinding/flaking with and without pre-cooling of celery seeds on the yield and physical and chemical characteristics of volatile oil was evaluated. For smaller batches (200 g) with pre chilling and flaking, yields of oil were marginally but consistently higher (2.20%), compared to grinding celery at ambient temperature using a mini plate mill (1.9%) and with waring blender (1.8%). With flaking at room temperature the yield of oil was 2.0%. However, in large batches (10 kg), with steam distillation the yield of steam distilled oil was significantly higher for flaking (1.76%) as compared to the hammer mill powdering (1.4%), both at room temperature. Extraction of volatile oil from celery powder or flakes follows first order kinetics with an variance value of 0.04. Gas chromatograph (GC) and gas chromatograph–mass spectra (MS) analysis showed that in case of flaking, the volatile oil had higher levels of limonene, the major volatile compound and sedanenolide, the major character impact compound being present in almost equal quantities in both the cases of flakes and powder. Selective collection of volatile oil at different intervals of time of distillation gave products of different flavour profiles. Flaking had the advantage of higher yields of the volatile oil with better flavour quality. It was also observed that flaking of celery helped in overcoming the problem of clogging and choking which is associated with the conventional grinding.     

Peeling an Onion: The Lexicographer's Experience ofManual Sense-Tagging

SENSEVAL set itself the task of evaluating automaticword sense disambiguation programs (see Kilgarriff andRosenzweig, this volume, for an overview of theframework and results). In order to do this, it wasnecessary to provide a `gold standard' dataset of `correct' answers. This paper will describe thelexicographic part of the process involved in creatingthat dataset. The primary objective was for a group oflexicographers to manually examine keywords in a largenumber of corpus contexts, and assign to each contexta sense-tag for the keyword, taken from the Hectordictionary. Corpus contexts also had to be manuallypart-of-speech (POS) tagged. Various observationsmade and insights gained by the lexicographers duringthis process will be presented, including a critiqueof the resources and the methodology.     

Exact filters for doubly stochastic AR models with conditionallyPoisson observations

The authors derive exact filters for the state of a doubly stochastic auto-regressive (AR) process with parameters which vary according to a nonlinear function of a Gauss-Markov process. The observations consist of a discrete-time Poisson process with rate a positive function of the Gauss-Markov process. The dimension of the sufficient statistic increases linearly with the number of observed events