Effects of salinity on synthesis of DNA, acidic polysaccharide, and growth in the blue-green alga, Gomphosphaeria aponina

A blue-green alga, Gomphosphaeria aponina, was grown in artificial sea water at salinities 20–36%. Fair to good growth was obtained at all salinities, and growth constants (K_e) were obtained. A parabolic relationship was obtained for the growth salinity relationship, e.g. (S−S_max)² = −2p(K_e−K′_e), where S and S_max is the given salinity and the maximum salinity, respectively, for which growth constants K_e and K_e^′ were obtained; p is a constant. The rate of DNA synthesis increased linearly with growth constant above K_e = 0.95 day⁻¹. Linear correlation coefficients were obtained for rate of polysaccharide synthesis and the rate of DNA synthesis, as well as for the rate of DNA synthesis and the rate of synthesis of aponin. The latter is material isolated from G. aponina and has cytolytic activity toward the Florida red tide organism, Gymnodinium breve, an unarmoured dinoflagellate.     

Modification of -equation in the SSRC Guide for buckling of monosymmetric I-beams under transverse loads

Finite element buckling analyses of monosymmetric I-beams subjected to transverse loading applied at different heights with respect to the mid-height of the cross-section were conducted. Transverse loads consisting of a mid-span point load and a uniformly distributed load were considered in the investigation. Four types of end restraint also were considered. The method suggested in SSRC Guide was compared with the finite element method (FEM) results. In order for C-equation in the SSRC Guide to be applicable for monosymmetric I-beams, it must be modified to contain three variables; A_m, B_m, and D_m. The first two variables A_m and B_m are modified variables A and B in the SSRC Guide whereas the third variable, D_m, developed herein, is the new modification factor for monosymmetric I-beams. The applicability of this new design rule is limited to monosymmetric I-beams in which the degree of monosymmetry, ρ, is within the range from 0.1 to 0.9.     

Factor interactions and aquatic toxicity testing

Hypothesizing that experimental variables constituting an exposure situation act independently when in combination, we have reviewed two published data sets dealing with effects of metal mixtures on aquatic animals in order to assess the potential practical significance of factor interactions and their implication to the design of aquatic toxicity tests. Both data sets were re-analyzed using each of the following predictive models: (1) simple-additive, y = a_x + b_y, where y is an estimated response, a_x is the observed response to a concentration of toxicant x when y = 0, and b_y is the observed response to a level of toxicant y when x = 0; (2) linear-additive, y = a + b₁x₁ + b₂x₂, in which y is a predicted value, a and b are pooled estimates involving all treatments in the exposure assay; (3) quadratic response, y = a + b₁x₁ + b₂x₂ + b₁₂x₁x₂ + b₁₁x₁² + b₂₂x₂², which provides for estimates of interactions and non-linear effects. The relative effectiveness of each model in predicting joint effects of independent test variables was evaluated in terms of calculated mean-square error and goodness-of-fit (R²) values, as well as by how well predicted treatment effects compared with responses observed by original investigators.Our analyses show that in one case all three models provided similar estimates that closely approximated observed responses, despite the presence of a statistically significant two-factor metal interaction. In comparison, in the second instance, the quadratic response model was the most effective predictor and was appreciably better than the linear-additive model in terms of the calculated parameters. The simple-additive model on the other hand, tended to over-estimate treatment effects, by as much as 80% in some instances, and was least effective of the three models examined. Our re-analyses show that the working hypothesis is rejected, i.e. an assumption of factor independence is not to be accepted a priori.A sequential testing protocol is presented which would permit an evaluation of the existence of factor interactions.     

Simulation of water-bloom in a eutrophic lake—III. Modeling the vertical migration and growth of Microcystis aeruginosa

The rate of vertical migration (rising or sinking) of Microcystis aeruginosa colonies in water was represented by Stokes' law. The density, p_p of the colony, estimated conversely from observations on vertical migration rate by using Stokes' law, was shown as a function of gas vacuoles' fraction, V_f in algal cells.Referring to the experimental studies by previous workers on factors that the affect the value of V_f, gas vacuoles in the cells were assumed to collapse instantly, V_f decreasing to V_feq once V_f values exceed those of V_feq. The latter values of V_feq were defined from a cumulative and normal distribution of gas vacuoles that withstand the turgor pressure. P, Incidentally, the regeneration rate of gas vacuoles in the cells that were subjected to sonication, yielding V_f = 0 (non-vacuolate) was constant regardless of the post-sonication environment of light and/or dark.Taking for granted that there exist upper and lower limits of turgor pressures for a given algal cell, an equation on the rate of change in turgor presure of the cell was derived. Presentation of these rate equations is a prerequisite for modeling and simulating emergence and/or disappearance of the waterbloom in still waters of eutrophic lakes and/or ponds.     

A laboratory study for assessing speech privacy in a simulated open‐plan office

The aim of this study is to assess speech privacy in open‐plan office using two recently introduced single‐number quantities: the spatial decay rate of speech, DL_2,S [dB], and the A‐weighted sound pressure level of speech at a distance of 4 m, L_p,A,S,4 m [dB]. Open‐plan offices were modeled using a DL_2,S of 4, 8, and 12 dB, and L_p,A,S,4 m was changed in three steps, from 43 to 57 dB. Auditory experiments were conducted at three locations with source–receiver distances of 8, 16, and 24 m, while background noise level was fixed at 30 dBA. A total of 20 subjects were asked to rate the speech intelligibility and listening difficulty of 240 Korean sentences in such surroundings. The speech intelligibility scores were not affected by DL_2,S or L_p,A,S,4 m at a source–receiver distance of 8 m; however, listening difficulty ratings were significantly changed with increasing DL_2,S and L_p,A,S,4 m values. At other locations, the influences of DL_2,S and L_p,A,S,4 m on speech intelligibility and listening difficulty ratings were significant. It was also found that the speech intelligibility scores and listening difficulty ratings were considerably changed with increasing the distraction distance (r_D). Furthermore, listening difficulty is more sensitive to variations in DL_2,S and L_p,A,S,4 m than intelligibility scores for sound fields with high speech transmission performances.     

Keys to species of Ceratacis and Synopeas from New Zealand,with the description of new species (Hymenoptera: Platygastridae)

Fifteen species new to science are described, viz. Ceratacis capitata, Ceratacis newzealandica, Ceratacis valentinei, Synopeas densisetosum, Synopeas denticorne, Synopeas elegans, Synopeas kristenseni, Synopeas lanuginosum, Synopeas marrisi, Synopeas motuhoropapense, Synopeas occipitocarinatum, Synopeas ramsayi, Synopeas terrestre, Synopeas trifolii, and Synopeas wardi. Keys to the hereby known N.Z. species of Ceratacis and Synopeas are provided.     

External mass transfer during the adsorption of various pollutants onto activated carbon

A wide range of experimental studies are reported for the adsorption of phenol and p-chlorophenol onto activated carbon—Type Filtrasorb 400—in an agitated batch adsorber. A model has been used to determine the external mass transfer coefficient for the systems and the effect of several experimental variables have been investigated: these include agitation, initial pollutant concentration, carbon mass, carbon particle size and solution temperature. The mass transfer coefficient has been correlated in terms of the dimensionless Sh/Sc^0.33 against each variable. The Sherwood number, Sh = k_fR/D_mol, relates the external mass transfer coefficient k_f to particle radius, R, and molecular diffusivity, D_mol. The Schmidt number, Sc, is the ratio of kinematic viscosity, v, to molecular diffusivity. A few results are also reported for the adsorption of sodium dodecyl sulphate and mercuric ions onto activated carbon.     

The “Underclass” Revisited: A Social Problem in Decline

Abstract: In the early 1980s, widespread concern over the social conditions of inner‐city neighborhoods gave rise to a literature on the “underclass.” A team of researchers led by Isabelle Sawhill, then of the Urban Institute, crafted a controversial operational definition of the underclass and found a rapid rise in the number of neighborhoods classifying as underclass in the 1970s and, to a lesser extent, in the 1980s ( Mincy and Wiener 1993 ; Ricketts and Mincy 1990 ; Ricketts and Sawhill 1988 ). The increasing prevalence of the underclass was linked to the increasing spatial concentration of poverty ( Wilson 1987 ). However, the concentration of poverty decreased in the 1990s ( Jargowsky 2003 ; Kingsley and Pettit 2003 ). This article reexamines the underclass measure in light of the change in concentrated poverty and finds a dramatic decline in the number of underclass neighborhoods in the 1990s.     

Influence of pore pressure on the drilling response in low-permeability shear-dilatant rocks

This paper examines the dependence of the drilling specific energy E (the amount of energy required to drill a unit volume of rock) on the virgin pore pressure p₀ in low-permeability fluid-saturated rocks, through a two-dimensional analysis of the cutting process. For this analysis, we consider a single cutter advancing at steady speed v and removing material over a constant depth of cut d from a fluid-saturated half-plane subjected to a surface pressure p_m and a far-field pore pressure p₀. On the basis of a simple failure mechanism involving a moving single shear plane (shear shock), we first establish that the specific energy E (here equal to the ratio of the cutting force parallel to the cutter velocity over the depth of cut) depends linearly on the difference between the surface pressure p_m and the average pore pressure p_b on the shear plane. Next, we address the dependence of p_b on the virgin pore pressure p₀ and the conditions for which there is cavitation on the shear plane (p_b=0). The relationship between p_b and p₀ is determined by considering fluid mass balance across the shear plane. Different pore pressure regimes are identified that are controlled by a dimensionless number λ: low-speed, transient, and high-speed regime. In the high-speed regime, the rock in the shear zone is undrained and pressure drop induced by shear-induced dilatancy leads to cavitation. It is shown that the drilling conditions in low-permeability shear-dilatant rocks, such as shales, are in the high-speed regime, leading therefore to the conclusion that the specific energy E does not depend on the virgin pore pressure p₀ in these rocks.     

Stochastic model for BOD and DO in streams when the velocity is random and distance‐dependent

The stochastic model studied in this paper is a random differential equation of the form X(t) = A(t) X(t) = Y(t), t ≥ 0, with initial conditions X₀ = X(0). X(t) is a vector with biochemical oxygen demand (BOD) and dissolved oxygen (DO) at a distance t downstream from the pollution source for components. The velocity of the stream is incorporated into the vector A(t) and is random and distance dependent. The inhomogeneous term Y(t) and the initial conditions are random vectors. Therefore, this model contains random initial conditions, random coefficients and random inhomogeneous terms. Simulated trajectories of the BOD and DO are computed.     

Crack coalescence in a rock-like material containing two cracks

This paper investigates the pattern of crack coalescence and strength of a sandstone-like material containing two parallel inclined frictional cracks under uniaxial compression, with changing values of inclination of preexisting cracks α, bridge angle β (inclination between the inner tips of the two preexisting cracks), and the frictional coefficient μ on the surfaces of the preexisting cracks. Three main modes of crack coalescence are observed: the shear (S) mode (shear cracking between the two preexisting cracks); the mixed shear/tensile (M) mode (propagation of both wing and shear cracks within the bridge area); and the wing tensile (W) mode (coalescence of wing cracks from the tips of the preexisting cracks). The M-mode and W-mode of crack coalescence can further be divided into two and six types, respectively. Simple regime classifications of coalescence in the α–β space are proposed for different values of μ (=0.6, 0.7 and 0.9). In general, the S-mode mainly occurs when α=β or when β<β*(α, μ)=a−bα, with both a and b depending on μ; the M-mode dominates when β_L>β>β*(α, μ) (where β_L≈82.5°); and the W-mode is only observed when β>β_L. However, more experiments are still required to refine the classification. The observed peak strength, in general, increases with μ. Our results show that the peak strength predicted by the Ashby and Hallam (1986) model basically agrees with experiments. A minimum occurs at about α=65° when the peak strength is plotted against α. For α>45°, the peak strength is essentially independent of the bridge angle β.     

CALENDER

Tsunami run-up heights (R) were predicted by using two different artificial neural network (ANN) methods such as feed forward back propagation (FFBP) and generalised regression neural networks (GRNN). The R records resulting from the ground motions, which occurred between 1900 and 2007, were used during the applications. These records were gathered from three coastal states of the USA, namely California (CA), Oregon (OR) and Washington (WA). First, the earthquake moment magnitude (M _w ), the distance from the earthquake source to the run-up location (D), the latitude of the run-up location (L _x ) and the longitude of the run-up location (L _y ) were used as inputs of each ANN method. In order to evaluate the effects of the L _x and L _y on the R prediction, a second input combination consisting of the M _w and D was used. Each ANN method structured for each input combination was applied to estimate the R of both the separate state and the Western Seaboard. In general, the forecasting performance of the FFBP model that used the M _w , D, L _x and L _y in the input layer was found superior to the other models under the conditions of the used data and model structures.     

Effect of artificial cementation on cone tip resistance and small strain shear modulus of sand

A series of cone penetration and bender element tests were performed on sands artificially cemented with gypsum in a calibration chamber to investigate the effect of cementation on the cone tip resistance (q _c) and small strain shear modulus (G _max) of sand. It was found that both the q _c and G _max of cemented sand are significantly affected by the degree of cementation while the effects of stress and density are reduced due to the cementation bonds. As the degree of cementation increases, the relationship between the q_\textc -D_\textR -s_\textv^￠ q_{{\text{c}}} {-}D_{{\text{R}}} {-}\sigma _{{\text{v}}}^{\prime } of cemented sand is observed to be similar to that of quartz sand with low compressibility. As the density and stress level affect q _c more significantly than G _max, the G _max/q _c of cemented sand decreases with increasing q _c. However, as the cementation causes a larger increase in G _max than q _c, the G _max/q _c ratio of cemented sand increases as the gypsum content increases. It was also observed from the G_max /q_\textc - (q_\textc /p_\texta )(p_\texta /s_\textv^￠ )^0.5 G_{{\max }} /q_{{\text{c}}} - (q_{{\text{c}}} /p_{{\text{a}}} )(p_{{\text{a}}} /\sigma _{{\text{v}}}^{\prime } )^{{0.5}} relation that the G _max/q _c ratio of cemented sand locates above the upper bound suggested by previous studies.     

A strategy for the fire testing of reduced scale structural models

A strategy for the fire testing of reduced scale structural models is developed which takes into consideration all significant thermostructural responses. An investigation of the thermal distributions within a structural element allows fire curve, thermal input and structural displacement output to be linked as cause and effect. Dimensional analysis permits the definition of the conditions necessary for dynamic similarity between model and prototype. An equivalent model fire curve is derived which can be mapped by a simple time scale factor on to a standard fire curve, though distortions due to film effects are noted. Errors due to temperature dependent properties are removed due to the nature of model and prototype temperature distributions. The principles are sensibly validated by low temperature experiments on perspex models of different scales. Finally, it is noted that a model test method would be advantageous for the provision of statistically meaningful amounts of indicative test data, with particular reference to parametric investigations. However, it is recognized that one-off full-scale tests must be conducted to provide the best final assessment of fire resistance.Nomenclature d structural element depth or thickness - d _m ;d _p thickness of model and prototype elements - E elastic modulus - F force on a small element slice - h _f film coefficient - k thermal conductivity - L significant longitudinal dimension or span - L _m ;L _p lengths in model and prototype - q heat flux - s scale factor - t generalized time interval - t _m ;t _p model and prototype test time scales - T generalized temperature - T _e equivalent linear temperature distribution - T _f furnace temperature - T _o average temperature through the thickness - T _x curvelinear temperature distribution - T _w element surface temperature - T ₁ –T ₅ thermocouple temperatures through the thickness - u lateral extension - y lateral displacement or bow - coefficient of linear thermal expansion - thermal diffusivity - T temperature difference over the thickness - slenderness ratio - ₁... _n dimensionless groupings - stress in element - _y material yield stress - () _m reference to model test variables - () _p reference to prototype test variables     

Financial effects of establishing a public office or public enterprise

This paper deals with the effects on municipal budgets of establishing public offices or enterprises. The methodology described can assist with locational decisions and quantifies employment, income, and financial effects with the help of a macroeconomic model. A measure for changes in the cash flow position of a town is also introduced Two examples — the establishment of a district heating firm and a concert hall — demonstrate different financial effects arising from the contrasting characteristics of each enterprise and the nearby towns most affected. Whereas the district heating firm increases the municipal cash flow, a reduction results from the establishment of the hall.Notation a ₁₂,a ₂₁ Grouped parameters indicating the effects of income variation in the hinterland on the settlement town's income and vice versa - a _1,2 Grouped parameters relating the variation of autonomous expenditure to total income of both regions - b ₁,b ₂ Grouped parameters which reflect the consequences of settlement measures for the settlement town and its hinterland - s _E ⁿ The relation of officials' salaries to total expenditure on the public office - n _E ^H1 The relation between additional lower rank employment for the inhabitants of the settlement town to the change in lower paid positions - n _v ^H The relation between employees and value added - dB _E ¹ Number of lower paid employees working at the public office - dB _A ¹ Lower paid employees who get jobs as a consequence of settlement actions - dN ^H1 Total employment effect - dN _E ^H1 The direct employment effect - dN _p ^H1 The indirect employment effect - c ₁,c ₂ Grouped parameters showing the effects of private and public debt on income in region 1 and region 2 - e _1,2 Grouped parameters for the demonstration of department movements due to total income variations - g Direct effects of autonomous expenditure on debt - dS _E Salaries for top officials - dS _E ^m Salaries for higher officials - dE Autonomous expenditure required for the actual establishment of the public office and for the necessary settlement measures - Y ^H1 The income effects - dY _E ⁿ Income of higher level officials employed at the public office and those who obtain jobs as a consequence of settlement actions - dY _E1 Income of lower paid employees working at the public office and those who obtain jobs as a consequence of settlement actions     

Frank Fenner,AC, CMG,MBE, FAA,FRS

The effect of Abate used in the control of Simulium damnosum on non‐target benthic invertebrate organisms was studied in river Oti (West Africa) in the Onchocerciasis Control Programme area. Abate was administered by aerial spraying and pre‐dosing and post‐dosing Surber samples were compared. Baetidae and Leptophlebiidae, two of the three predominating organisms were seriously affected by the Abate. Other non‐target organisms that were killed were Gomphidae, Libellulidae and Dytiscidae. Though the larvicide was toxic to other non‐target organisms, particularly Neoperla and Orthocladinae, the effect did not seem to be significant.     

Cinetiques et mecanismes de l'action oxydative de l'hypochlorite sur les acides α-amines lors de la desinfection des eaux

In the field of water treatment, one increased concern over the quality of the environment requires an understanding of the fate of compounds generated by the addition of chemicals. One area of considerable interest is the stability of chlorine compounds produced when chlorine is added to natural water or swimming pool water. It is desirable to be able to predict the lifetimes of these harmful compounds under various conditions. In this study we examine for a range of hypochlorite α-amino acid ratios and pH, the kinetics and mechanism of the decomposition of α(N-chloro) and α(N,N-dichloro) amino acid, one of the products of chlorination.The interaction of chlorine with amino acids has been studied by several investigators Langheld (1909) was the first who discussed the decomposition of the α(N-chloro) amino acids. He noted that hypochlorous acid salts react with α-amino acids in the same manner as they do with amines to form monochlorinated or dichlorinated derivatives. Then, the decomposition of chloro-amino acids leads to the corresponding aldehydes or ketones, ammonia, carbonic acid, and sodium chloride. As an intermediate step Langheld assumed an imine formation.Wright (1936) and Pereira et al. (1973) have investigated the decomposition products of α(N,N-dichloro) amino acids. Their results indicate rapid formation of carbon dioxide, chloride ion, and the corresponding nitrile.Recently, many authors have investigated the rates of α(N-chloro) amino acids decomposition and the stability of its products (William and Wendy, 1979; Yoshiro et al., 1980; Le Cloirec-Renaud, 1984). However, they have neither differentiated between the decomposition of α(N-chloro) amino acid and α(N,N-dichloro) amino acid, nor have they demonstrated the combined effect of pH and molar ratio of hypochlorite and α-amino acid.In this study the hypochlorite oxidation of simple α-amino acids in aqueous solution has been investigated in the dark. The concentration of α(N-chloro) amino acid and α(N,N-dichloro) amino acid was monitored by DPD-fast titrimetric method and by measuring the absorbance at 255 and 293 nm respectively, this is illustrated in Figs 3 and 4. These results and the amino acids determination (O-phtalaldehyde—2 mercapto ethanol method) suggest that the intermediates α(N-chloro) and α(N,N-dichloro) amino acid are formed rapidly at an initial stage. Then, they decompose spontaneously by first order kinetics as shown in Table 1, to give a mixture of aldehyde and nitrile.When equimolar (1:1 mmol) amounts of hypochlorite and amino acid are used at pH 7, only aldehyde, carbon dioxide, chloride and ammonia are formed. However the corresponding nitrile compound appears, when operating condition allow the formation of α(N,N-dichloro) amino acid (acid pH or basic aqueous solutions with high molar ratio of hypochlorite and amino acid). This is illustrated in Table 2. The rate constant shows a dependence on pH, which is caused by the various forms that can arise from addition of protons to or removal of protons from the amino and carboxyl groups of the molecule William and Wendy, 1979). We assume an intermediate step of imine for the decomposition of both compounds: α(N-chloro) and α(N,N-dichloro) amino acid (scheme 6). The reaction should be considered as a spontaneous decarbonylation followed by a rapid hydrolysis of the imine. Scheme 7 illustrated how α(N,N-dichloro) amino acid can lead to the corresponding nitrile and aldehyde, however the α(N-chloro) amino acid gives only the corresponding aldehyde.The products of decomposition of α(N-chloro) amino acid are relatively stable in aqueous solution. Although we noted at pH = 3.5–5 that aldehyde react with chloramines and lead to the formation of corresponding nitrile, as shown in scheme 9.It appears that α(N-chloro) and α(N,N-dichloro) amino acid formed during the chlorination of natural or swimming pool water will degrade in a few hours to what are probably irritating products (like as aldehydes). The production of decomposition are a function of molar ratio of hypochlorite and amino acid and pH. However, since most natural water has a pH in the range of 5.5–9, there will be little variation of the rate of decomposition with pH. It seems that it is only temperature dependent.     

Measurements of the characteristic lengths of smoke detectors

The dynamic performance of point-type smoke detectors is described by a simple model including two independent parameters, the static response threshold, and the characteristic length of the detector. An experimental system with constant rate of increase of smoke density under varying velocity conditions is used to determine the model parameters.Nomenclature k constant smoke density gradient (dB/m/s) - L characteristic length of the detector (m) - m _i smoke density inside the detector (dB/m) - m _o smoke density outside the detector (dB/m) - m _or measured smoke density at response (dB/m) - m _r response threshold of the detector (dB/m) - t time(s) - v gas flow velocity at the detector (m/s) - time constant(s)     

Emission strength of airborne pathogens during toilet flushing

The flushing of toilets generates contaminated aerosols, the transmission of which may cause the spread of disease, particularly in the immunocompromised or the elderly. This study investigated the emission strength of three types of airborne bacteria, namely Staphylococcus epidermidis, Escherichia coli, and Pseudomonas alcaligenes, during toilet flushing in a custom‐built toilet under a controlled environment. Flushing was activated by a flushometer operated at two pressure levels, 400 kPa (high pressure [HP]) and 200 kPa (low pressure [LP]), and by a water cistern tank placed 95 cm (high tank [HT]) and 46 cm (low tank [LT]) above the toilet seat. The pathogens emitted by the first flush were calculated, with the correlations between airborne pathogen emissions and droplet concentration (HP, r=0.944, P<.001; LP, r=0.803, P<.001, HT, r=0.885, P<.05) and bacterial size (HP, r=?0.919, P<.001; LP, r=?0.936, P<.001; HT, r=?0.967, P<.05) in the different conditions then tested. The emission strength in the HP condition was statistically greater than that in the LP condition, whereas the cistern tank system produced less emissions than the flushometer system, and tank height was not found to be a sensitive parameter.     

A comprehensive study on the biological treatabilities of phenol and methanol—I. Analysis of bacterial growth and substrate removal kinetics by a statistical method

An unbiassed statistical method was developed to evaluate kinetic parameters in the biological oxidation of wastewaters. Through the statistical analyses of the biological oxidation kinetics, it was shown that the kinetic equations satisfactorily described the bacterial growth and substrate removal kinetics where X is biomass concentration, S is substrate concentration, t is time, a is cell yield coefficient, k_d is cell decay coefficient, K_s is Michaelis-Menten constant, and k is substrate removal rate coefficient. The coefficients K_s and a changed with temperature insignificantly while k and k_d were closely related to it. The temperature independent coefficients K_s and a were estimated to be 236 mg 1⁻¹ (standard deviation, σ = 70 mg 1⁻¹) and 1.21 (σ = 0.06) respectively for phenol, and 2330 mg 1⁻¹ (σ = 1410 mg 1⁻¹) and 1.25 (σ = 0.45) respectively for methanol based on total organic carbon (TOC) and volatile suspended solids (VSS). The oxygen utilization rate can be formulated as where Rr is the oxygen utilization rate (mg 1⁻¹ O₂ time⁻¹), as′ is a coefficient designating oxygen requirement per substrate utilized, and b′ is a coefficient designating oxygen requirement per biomass for endogeneous respiration. The coefficient a′ was 1.39 for phenol and 2.23 for methanol, and b′ was 1.42 k_d for both substances based on TOC and VSS.