Treatment of paper mill effluent using an anaerobic/aerobic hybrid side-stream membrane bioreactor

This paper presents the design and operational performance data of an anaerobic/aerobic hybrid side-stream Membrane Bioreactor (MBR) process for treating paper mill effluent operated over a 6 month period. The paper mill effluent stream was characterized by a chemical oxygen demand (COD) range of between 1,600 and 4,400 mg/L and an average BOD of 2,400 mg/L. Despite large fluctuations in COD feed concentration, stable process performance was achieved. The anaerobic Expanded Granular Sludge Bed (EGSB) pre-treatment step effectively lowered the organic loading by 65 to 85%, thus lowering the MBR COD feed concentration to consistently below 750 mg/L. The overall MBR COD removal was consistent at an average of 96%, regardless of the effluent COD or changes in the hydraulic retention time (HRT) and organic loading rate (OLR). Combining a high-rate anaerobic pre-treatment EGSB with a Modified Ludzack-Ettinger (MLE) MBR process configuration produced a high quality permeate. Preliminary NF and RO results indicated an overall COD removal of around 97 and 98%, respectively.     

In vitro growth and drug sensitivity of tumor colony-forming units from human tumor xenografts

To investigate the feasibility of using tissue obtained from human tumor xenografts for in vitro screening of antineoplastic agents, we grew human tumor colony-forming units (CFU) in semisold agar from xenografts serially passaged in nude mice. Growth of human tumor CFU was accomplished from nine xenografts representing five different histological tumor types (ovarian carcinoma, adenocarcinoma of the colon, malignant melanoma, epidermoid carcinoma of the lung, and malignant astrocytoma). Cloning efficiency ranged from 0.04 to 0.1% and showed significant variability both between tumor types and between individual animals bearing the same type of xenograft. A high percentage of tumor CFU was in S phase [47 +/- 20% (S.D.)] as determined by the thymidine "suicide" technique. The number of tumor CFU observed increased linearly with increasing numbers of cells plated. In vitro drug sensitivity of the tumor CFU was assessed to Adriamycin, cis-platinum, and melphalan. The patterns of drug sensitivity were found to be reproducible and stable over a period of 9 months. Drug sensitivity curves to Adriamycin for five xenografts representing four tumor types showed complex patterns with plateau portions similar to those described for tumor CFU from primary tumors. The rank order of sensitivity of the tumors was compared to that of normal granulocyte-macrophage progenitors and, with the exception of the melanomas, was found to correlate well with clinical experience (order of sensitivity = colon less than ovary less than bone marrow). Growth of human tumor CFU from xenografts represents a reproducible and stable means for the study of the biology of tumor CFU and has potential applications as a means for screening new anticancer agents.     

Micro-yielding in a precipitation hardening Cu 1.81 wt % Be 0.28 wt % Co alloy

The microstrain characteristics of a polycrystalline Cu 1.81 wt % Be 0.28 wt % Co precipitation hardening alloy have been determined for various precipitate conditions. The friction stress derived from measurements of closed hysteresis loops was found to remain constant ( 3 MN m^–2) for all the conditions investigated. In contrast, the microscopic yield stress (MYS) remained constant (18 to 24 MN m^–2) for most ageing conditions, but increased significantly (to 48 to 64 MN m^–2) for conditions associated with a high G.P. zone or precipitate density.     

The effect of antioxidants on the production, of volatile nitrosamines during the frying of bacon

Summary In model system studies simulating the frying of bacon a considerable variation in the production of N-nitrosopyrrolidine (NOPyr) has been observed, as occurs in sliced bacon fried conventionally. The inclusion of ascorbate or erythorbate (isoascorbate) has led consistently to a fall in or an elimination of NOPyr production up to an addition of 300 ppm (1,5 mM). Above this concentration of ascorbate, the elimination of NOPyr formation persisted in some instances but in others an increased production of the nitrosamine occurred. Using-tocopherol, a fall of NOPyr production during the simulated frying of bacon was obtained with increase of concentration of the antioxidant, there being a consistent elimination of the volatile nitrosamine following an addition of 500 ppm (1.16 mM). Whilst ascorbyl palmitate had a similar action in reducing or eliminating NOPyr production, no synergistic effect between it and a-tocopherol was noted in an experiment combining the two antioxidants. When bacon was fried in fat containing 400 or 800 ppm-tocopherol, the total production of NOPyr and DMN in the fried bacon, cooked out fat and condensate was markedly reduced but not completely eliminated as in the model system studies. Similarly, the curing of bacon with a brine containing a mixture of-tocopherol, ascorbyl palmitate and citric acid has led to considerable reductions in NOPyr and DMN output on frying when the combined concentrations of the two anti-oxidants were calculated to be 800 ppm.

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Der Einfluß von Antioxydantien auf die Entwicklung flüchtiger Nitrosamine während des Bratens von Speck

Zusammenfassung Bei Untersuchungen in Modell-Systemen, in denen das Braten von Speck simuliert wurde, stellte man eine nennenswerte Variation in der Entstehung von N-Nitrosopyrrolidin (NOPyr) fest, wie sie auch bei konventionell gebratenem Scheibenspeck auftritt. Der Zusatz von Ascorbat oder Isoascorbat hat bei einem Zusatz bis zu 300 ppm (1,5 mmol) regelmäßig zur Abnahme der NOPyr-Produktion geführt. Bei größerer Ascorbatkonzentration nahm die NOPyr-Bildung in einigen Fällen ab, in anderen setzte dagegen eine erhöhte Nitrosaminbildung ein. Bei Anwendung von-Tokopherol wurde eine Abnahme in der NOPyr-Bildung während des simulierten Bratens von Speck bei zunehmender Antioxydantien-Konzentration erreicht, wobei ein gleichbleibendes Verschwinden des flüchtigen Nitrosamins eine Folge des Zusatzes von 500 ppm (1,16 mmol) war. Während Ascorbylpalmitat eine ähnliche Wirkung in der Reduzierung der NOPyr-Bildung hatte, konnte bei einem Experiment, bei dem die beiden Antioxydantien zugegen waren, keine synergistische Wirkung festgestellt werden. Wenn Speck in 400 oder 800 ppm-Tokopherol enthaltendem Fett gebraten wude, war die Gesamtbildung von NOPyr und DMN in dem gebratenen Speck, dem ausgekochten Fett und im Kondensat wesentlich reduziert, aber nicht wie bei den Modell-System-Versuchen vollständig eliminiert. Ähnlich führte auch das Pökeln von Speck in Lake, die eine Mischung von-Tokopherol, Ascorbylpalmitat und Citronensäure enthielt, zu wesentlicher Reduzierung in NOPyr- und DMN-Produktion beim Braten, wenn die Konzentration der beiden Antioxydatien zusammen auf 800 ppm berechnet wurden.

     

Effect of tinidazole, metronidazole and nitrofurazone on nucleic acid synthesis in Clostridium bifermentans

Coplanar lines of different orientations rotating in depth and viewed in parallel projection may appear to rotate in different directions and reverse independently of each other, or they may appear coplanar and all reverse together. The frequency of the latter "grouped" appearance for lines with an orientation range of 30 degrees was a function of the number of lines in a given space. Grouping was greater for lines converging to an implicit vanishing point and for lines with collinear edges regardless of their orientations. Line length, and by inference, interline separation also had effect of the nature of the response.     

Bandwidth requirements for accurate detection of direct path in multipath environment

The accurate detection of the direct path in a dense multipath environment is critical in time-based and angle-of-arrival-based location estimation techniques. It is generally assumed that an infinitely large bandwidth is helpful in the accurate detection of the direct path and high-range resolution. It is experimentally demonstrated that, for a wideband system, a bandwidth of up to 4 GHz, centred on 12.5 GHz, is sufficient for accurate detection of direct path in a typical indoor scattering environment. Additionally, the bandwidth gain, incremental range accuracy with bandwidth, is an effective indicator of the bandwidth requirements for accurate detection of the direct path.     

Experiments and simulations of short-pulse laser-pumped extreme ultraviolet lasers

Recent experimental work on the development of extreme ultraviolet lasers undertaken using as the pumping source the VULCAN laser at the Rutherford Appleton Laboratory is compared to detailed simulations. It is shown that short duration (/spl sim/picosecond) pumping can produce X-ray laser pulses of a few picosecond duration and that measurement of the emission from the plasma can give an estimate of the duration of the gain coefficient. The Ehybrid fluid and atomic physics code developed at the University of York is used to simulate X-ray laser gain and plasma emission. Two postprocessors to the Ehybrid code are utilized: 1) to raytrace the X-ray laser beam amplification and refraction and 2) to calculate the radiation emission in the kiloelectronvolt photon energy range. The raytracing and spectral simulations are compared, respectively, to measured X-ray laser output and the output of two diagnostics recording transverse X-ray emission. The pumping laser energy absorbed in the plasma is examined by comparing the simulations to experimental results. It is shown that at high pumping irradiance (>10/sup 15/ Wcm/sup -2/), fast electrons are produced by parametric processes in the preformed long scalelength plasmas. These fast electrons do not pump the population inversion and so pumping efficiency is reduced at high irradiance.     

Optical deflection measurement for characterization of microelectromechanical systems (MEMS)

Nonintrusive measurement of small out-of-plane motions of microscale structures is critical to the development of microelectromechanical systems (MEMS). This paper presents a low-cost deflection measurement system for MEMS structures based on a fiber optic displacement sensor. The system is demonstrated in the characterization of a microwave switch. The deflection system had a demonstrated sensitivity of 290/spl plusmn/32 /spl mu/V/nm over a deflection range of 100 /spl mu/m. The calibration and linearity of the system are described, and the static and dynamic performance is compared to more elaborate systems.     

Alzheimer paired helical filaments (PHFs) studied by high-resolution TEM: what can vertical Pt-C replication tell us about the organization of the pronase-digested PHF core?

Untreated paired helical filaments (PHFs) and pronase-digested PHF-core filaments were stereoscopically imaged with a freeze-drying vertical platinum-carbon replication preparation method for TEM. The untreated PHF have an average wide region (W) = 22.8 +/- 2.4 nm, a narrow region (T) = 10.6 +/- 1.7 nm, and a helical turn period (L) = 78.6 +/- 13.4. The surfaces of the untreated PHF's fuzzy coat appears disorganized. The widths of the pronase-treated PHF-core filaments were significantly reduced (W(d) = 14.8 +/- 1.2 nm, T(d) = 5.7 +/- 1.0 nm, and L(d) = 75.4 +/- 17 nm). The surfaces of the untreated PHF contained approximately 1.1 nm strands, the same size as tau monomer ( approximately 1.0 nm). The pronase-digested PHF cores mostly contained approximately 1.6 +/- 0.3 nm strands although strand diameters ranged from 0.6-2.5 nm. The strands sometimes appear to be wrapped around the filament axis; less often, they appear to be roughly parallel to the PHF axis, and otherwise appear to be randomly oriented. Images of pronase-digested PHF core images are discussed in relation to the core's biochemical composition, its proposed beta structure, and structural subunit models. Images of the untreated and the pronase-digested PHF support a helical ribbon morphology.