A new method of measuring and presenting the membrane fouling potential

The silt density index (SDI) and modified fouling index (MFI) characterisation methods are well known for the evaluation of membrane fouling potential of dispersed particulate matter (suspended solids, colloids) in a feed. The SDI and MFI methods, however, reduce the overall and very complex fouling phenomena into a one number value, on which the interpretation of the fouling potential of the feed is based. Considering such a one number characteristic, a significant amount of information from the fouling measurement (data) is lost. In this paper a concept is introduced in order to preserve such information and supplement the existing indexes. The proposed method measures, processes and presents data in a specific format. To illustrate the concept, some results are shown from measurements on three types of feed. Future systematic research will also include the measurement on some model feeds with, for example, well characterised dispersions for comparison purposes. However, based on the contents of this paper, a discussion on the method could be initiated.     

Band gap opening and charge modulation in AlGaAs lateral structures obtained by organized epitaxy

Quantum wires superlattices have been grown on GaAs vicinal surfaces. Their electrical resistance anisotropy, their low-field magnetoresistance (for current flow perpendicular to the wires) and, in the magnetic quantum limit, the van Hove singularities of the Landau bands, and the very sudden enhancement of the spin splitting above a critical field, all demonstrate unambiguously that a strong low-disordered periodic lateral potential modulation can be achieved as a result of significant atomic ordering by the steps.     

Identification of xanthurenic acid as the putative inducer of malaria development in the mosquito

Malaria is transmitted from vertebrate host to mosquito vector by mature sexual blood-living stages called gametocytes. Within seconds of ingestion into the mosquito bloodmeal, gametocytes undergo gametogenesis. Induction requires the simultaneous exposure to at least two stimuli in vitro: a drop in bloodmeal temperature to 5 degrees C below that of the vertebrate host, and a rise in pH from 7.4 to 8.0-8.2. In vivo the mosquito bloodmeal has a pH of between 7.5 and 7.6. It is thought that in vivo the second inducer is an unknown mosquito-derived gametocyte-activating factor. Here we show that this factor is xanthurenic acid. We also show that low concentrations of xanthurenic acid can act together with pH to induce gametogenesis in vitro. Structurally related compounds are at least ninefold less effective at inducing gametogenesis in vitro. In Drosophila mutants with lesions in the kynurenine pathway of tryptophan metabolism (of which xanthurenic acid is a side product), no alternative active compound was detected in crude insect homogenates. These data could form the basis of the rational development of new methods of interrupting the transmission of malaria using drugs or new refractory mosquito genotypes to block parasite gametogenesis.     

Pronunciation prediction with Default&Refine

The Default&Refine algorithm is a new rule-based learning algorithm that was developed as an accurate and efficient pronunciation prediction mechanism for speech processing systems. The algorithm exhibits a number of attractive properties including rapid generalisation from small training sets, good asymptotic accuracy, robustness to noise in the training data, and the production of compact rule sets. We describe the Default&Refine algorithm in detail and demonstrate its performance on two benchmarked pronunciation databases (the English OALD and Flemish FONILEX pronunciation dictionaries) as well as a newly-developed Afrikaans pronunciation dictionary. We find that the algorithm learns more efficiently (achieves higher accuracy on smaller data sets) than any of the alternative pronunciation prediction algorithms considered. In addition, we demonstrate the ability of the algorithm to generate an arbitrarily small rule set in such a way that the trade-off between rule set size and accuracy is well controlled. A conceptual comparison with alternative algorithms (including Dynamically Expanding Context, Transformation-Based Learning and Pronunciation by Analogy) clarifies the competitive performance obtained with Default&Refine.     

Pore microgeometry analysis in low-resistivity sandstone reservoirs

The objective of this work is to analyse the pore microgeometry and its effect on petrophysical properties in six low-resistivity sandstone reservoirs by combining a 2D quantitative petrographic image analysis (PIA) and 3D petrophysical tools. The classic petrophysical tools enable the measurement of different classic reservoir properties such as specific surface area, average pore diameter, pore size distribution, macroporosity and microporosity, capillary pressure versus saturation, pore chamber–pore throat diameter ratio, electrical properties and permeability. The petrographic image analysis quantifies pore microgeometry in more than four orders of magnitude, from submicron to millimeter scale. Chloritic low-resistivity sandstones show dual porosity structure defined as chloritic texture. The pore microgeometrical parameters measured by petrographic image analysis allow one to model different reservoir properties such as capillary pressure, permeability and electrical behaviour. The results obtained in these models show that pore microgeometry plays an important role in the physical properties of low-resistivity sandstone reservoirs.     

PROTEIN PRECIPITATION DURING WORT BOILING: QUALITY ASPECTS OF DIMINISHED WORT BOILING TIMES OF BREWS PREPARED FROM PROANTHOCYANIDIN-FREE OR REGULAR RAW MATERIALS

When using proanthocyanidin-free materials for the production of beer, a reduction of the wort boiling time can be considered. In worts prepared with regular malt and tannin-free hop extract there is a continuous precipitation of the malt flavanoids while in brews prepared from proanthocyanidin-free malt and regular hops there is a simultaneous extraction and removal of the hop flavanoids leading to constant levels of these hop flavanoids. The results also show that the level of Kjeldahl nitrogen in worts boiled with hops will be the same as that in worts boiled with n-hexane tannin-free hop extracts. These results and the fact that more protein precipitates in brews containing no malt or hop proanthocyanidins suggest that, unlike what is the case during the development of beer haze, polyphenols are not necessary for an effective protein precipitation during wort boiling.     

Thermodynamic and spectroscopic measurements of the electron-hole drop binding energy in Ge: An old problem revisited

One can expect to get the electron-hole (EHD) binding energy φ either from spectroscopic or from threshold measurements. While the value obtained by the former is in excellent agreement with theory, the results given by the latter did not seem to lead to φ in a simple way. We present here new optical threshold studies in which we think that the right conditions to obtain a direct thermodynamic measurement of φ have been mastered. Besides, our results present novel features like a sharp jump of the EHD luminescence at threshold above 2.4 K and observation of hysteresis in the whole temperature range of our work.     

Shock wave pulse pressure after penetration of kidney tissue

Lithotripter generated compressional peak pressure (p⁺) was measured after penetrating tissue samples 0.5, 1, 2.5, and 4 cm thick. The samples were taken from fresh pig kidneys and insonated by shock wave pulses with positive peak pressures varying from 14 to 72 MPa. The measurement results allow one to draw some qualitative conclusions concerning the attenuation process in the lithotripter beam and show that in practice the compressional peak pressure values generated in the lithotripter may decrease almost by a factor of two before reaching the kidney stone. On the contrary, theoretical estimates indicate that negative pressures are practically not influenced by attenuation due to their different spectral composition     

Current results of endoscopic sphincterotomy for lithiasis of the common bile duct

Between January 1989 and June 1990, endoscopic sphincterotomy was performed in 308 consecutive patients with common bile duct stones (mean age: 74 years). Complete clearance of common bile duct was achieved at the first attempt in 65% of cases. This rate was significantly related to the size and the number of biliary stones. The success rate reached 97 percent after repeated endoscopic sessions (127 patients), mechanical lithotripsy (20 patients), extracorporeal or intracorporeal lithotripsy (18 and 11 patients, respectively). During the month following the endoscopic sphincterotomy, 39 patients (13%) developed one or more complications and 11 patients (3.7%) died. The complication rate was related to the time elapsed between biliary opacification and endoscopic sphincterotomy (P = 0.04) and between endoscopic sphincterotomy and total common bile duct clearance (P = 0.0007). No patient younger than 75 years died, but death occurred in 4.5% of the patients older than 75 years. Thirty patients (10%) developed endoscopic sphincterotomy-related complications. Cholangitis and bleeding were the most frequent complications (4 and 2%, respectively). Cholangitis occurred more frequently among the patients older than 75 (P < 0.05) or when transhepatic guided endoscopic sphincterotomy or intracorporeal lithotripsy was used (P < 0.005). Cholangitis led to death in 2 patients, 86 and 87 years old (0.7%). Endoscopic sphincterotomy related complications developed within 48 hours in all but 4 patients (2 patients with pancreatitis and 2 patients with cholecystitis).     

AREP在中国

2005年．AREP在华的首批工程在北京（首都博物馆、西直门交通枢纽）与天津（泰达金融中心、泰丰住宅区）拉开了序幕。