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A theoretical investigation on the redox processes in the subphthalocyanines (SubPcs) was performed. Singly and doubly oxidative and reductive transformations were considered. The full geometry optimization of the participating molecules showed that the cone shape arrangement of the SubPc is preserved in their ionic derivatives even when two electrons are either donated or subtracted from the molecule. The biggest geometric changes under electron exchange processes were calculated for the B—Cl bond distance. The electronic density distribution over all the products remains almost invariable with respect to the neutral molecule. Our calculations on the neutral and charged SubPcs demonstrated that they behave as conjugated systems, their electronic parameters being correlatively altered by the redox electron exchange. Further, the electronic state of the macrocycle atoms also depends on an intense electronic flow among the macrocyclic skeleton and the surrounding (axial chlorine and peripheral hydrogen) atoms that is associated with the redox process. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 [ABSTRACT FROM AUTHOR]

The term "( HT ht )" is misspelled as "( HT ht )" in Eqs. In the second paragraph following Eq. (15), the second- and third-to-last sentences should read as follows: "The associated relative errors were restricted in the range of HT ht , with the mean absolute relative errors (MARE) ( HT ht ) of 6.02% and 4.8% for criteria HT ht and HT ht , respectively. [Extracted from the article]

• Theoretical flow resistance equation is calibrated and tested by Sun et al. data. • The effect of tillage-induced roughness on flow resistance is tested. • Accurate friction factor estimate for tillage-induced resistance is obtained. • Darcy–Weisbach friction factor due to tillage-induced resistance varies with time. For concentrated flows, which are characterized by small water depth and steep sloping beds, hydraulic conditions different from those typical of streams and rivers occur. In this study a new theoretically deduced flow resistance equation was tested using the experimental data by Sun et al. for three different tilled surfaces (Manual Dibbling, MD, Manual Hoeing, MH, and Contour Drilling, CD). At first, the profile parameter-relationship, which is the relationship between the velocity profile parameter Γ, the channel slope and the flow Froude number, was calibrated using rill flow data by Di Stefano et al. Then, the applicability of this relationship was tested by the measurements of Sun et al. The calculated Darcy–Weisbach friction factor values were generally lower than those measured by Sun et al. and this result was justified taking into account that the rill measurements used for calibrating the profile parameter-relationship simply correspond to grain resistance conditions. For taking into account both grain resistance and tillage induced surface roughness, the profile parameter-relationship was calibrated by the measurements by Sun et al. This calibration was carried out for each tillage practice (MD, MH and CD) and using all the measurements carried out during each 20 min – experimental run. This study was also developed using exclusively the data concerning the beginning of the experiment (0–4 min), in order to state the effect of the initial roughness, and those regarding the end of the experiment (16–20 min) to estimate the influence of the temporal evolution of roughness on the friction factor. The study proved that the Darcy–Weisbach friction factor due to grain resistance and tillage induced roughness can be accurately estimated using the proposed theoretical approach. A temporal variation of the Darcy–Weisbach friction factor was also recognized. Finally, the data were supportive of the slope independence hypothesis of flow velocity stated by Govers. [ABSTRACT FROM AUTHOR]

• Rainfall intensity, I s , depends on pressure head, H , and water temperature, T. • I s is the only variable that affects the mean mass of a single drop. • For falling height, h less than 1.3 m the raindrop fall velocity, v is function of h. • Rainfall kinetic power and momentum are function of I s and h. • The Kamphorst characterization needs to know the nozzle geometry, H , T , and h. In this paper, the results of the characterization of Kamphorst's rainfall simulator obtained by laboratory experiments carried out at the Department of Agricultural, Food, and Forest Sciences of the University of Palermo, are presented. At first, the rainfall uniformity distribution was positively verified considering several pressure heads (ranging from 1.9 cm to 11.9 cm) and water temperatures (from 24 °C to 27 °C), achieving a uniformity coefficient ranging from 96 to 99 %. Then, using a single nozzle, the simulator has been characterized in terms of kinetic power and momentum by applying both a photographic and a weighing technique. In particular, terminal drop velocity was measured by the displacement of a single raindrop measured between two consecutive frames, while the mean mass of single drops was evaluated by weighing a fixed number of drops. The analysis of the experimental data highlighted that the rainfall intensity, which increases with water temperature and pressure head, is the variable affecting the measurement of the single raindrop mass. Measurements also showed that an increase in rainfall intensity determines a decrease in the mean mass of the raindrops and an increase in the number of raindrops that fall in the unit time and area. This circumstance allowed to justify the increasing trend of the rainfall kinetic power and momentum with rainfall intensity. The measurements allowed to develop empirical relationships relating kinetic power and momentum with the simulated rainfall intensity and falling height of the raindrops. Finally, a theoretical expression suggested in the literature for estimating simulated rainfall intensity was positively tested. [ABSTRACT FROM AUTHOR]

Presents abstracts related to surgical research presented at the Royal Australasian College of Surgeons 1998 Annual Scientific Congress. 'A Novel Suphated Oligosaccharide and Human Colorectal Cancer,' by E. Bolton, Y. Lu et al; 'Gelatinase Secretion and Activation in Colon Cancer,' by M.V. Agrez, X. Gu et al.

Since rill flows are characterized by small water depths and steeply sloping channels, the corresponding hydraulic conditions are very different to those which are typically found in channels of streams and rivers. Furthermore, limited information is currently available on the effect of rainfall on flow resistance. The objective of this comment was to investigate the applicability of a recently theoretically deduced rill flow resistance equation, based on a power-velocity profile, using measurements carried out by Jiang et al. for both different slope steepness conditions and rainfall intensity. The relationship between the velocity profile parameter Γ, the channel slope and the flow Froude number was calibrated using the data by Jiang et al. The theoretical approach and the measurements carried out in the investigated conditions allowed to state that a) the Darcy-Weisbach friction factor can be accurately estimated using the proposed theoretical approach, b) the data were supportive of the slope independence hypothesis of rill velocity stated by Govers and c) the Darcy-Weisbach friction factor varies with rainfall intensity. • The effect of rainfall on flow resistance is tested. • Theoretical rill flow resistance equation is calibrated by available data. • Slope independence hypothesis of rill velocity is stated. • Darcy-Weisbach friction factor varies with rainfall intensity. [ABSTRACT FROM AUTHOR]

In this paper the results of the experiments performed to study the flow through a Triangular Central Baffle Flume (TCBF) are reported. The investigated flume consists of a triangular baffle of the apex angle of 75° with a given base width. The theoretical stage-discharge formula was deduced by applying the Buckingham's Theorem and incomplete self-similarity hypothesis and was calibrated using the laboratory measurements carried out in this investigation. The proposed stage-discharge formula is characterized by a mean absolute relative error of 7.4% and 72% of the data points are in an error range of ±5%. The results indicate that TCBF flume is characterized by a flow capacity higher than that of a typical central baffle flume. Experimental observations show that the contraction ratio is a key parameter to distinguish between free and submerged flow regimes through a TCBF. Finally, to identify the flow condition, submergence threshold condition was formulated. • A flow measuring device called as Triangular Central Baffle Flume, TCBF, is presented in this study. • Experiments are performed to formulate the stage-discharge curve for free flow condition. • Submergence threshold curve is studied experimentally to identify the flow condition through TCBF. [ABSTRACT FROM AUTHOR]

Gates are simple hydraulic structures which have been widely used for flow control and measurement in irrigation networks. In this paper new sluice gates with cylindrical and semi-cylindrical edges were introduced and the flow movement below these types of gates was experimentally investigated for both free- and submerged-flow conditions. The Buckingham theorem of dimensional analysis and the self-similarity theory were applied for developing the stage-discharge relationships for the two investigated flow conditions. For these cylindrical and semi-cylindrical edged gates and a free-flow condition, the proposed stage-discharge relationship was characterized by an estimate error less than or equal to 5% for 96.0% and 93.7% of the calculated values, respectively. Finally, an equation for calculating the maximum tail water depth allowing free flow condition was proposed. • Cylindrical and semi-cylindrical edged sluice gates are experimentally investigated. • Theoretical stage-discharge equation is deduced for free and submerged-flow condition. • The theoretical stage-discharge relationship is calibrated by flume data. • Maximum tail water depth allowing free flow condition is determined. [ABSTRACT FROM AUTHOR]

The article offers the authors' insights regarding the analysis developed by the discussers of the article "Stage-Discharge Relationship for an Upstream Inclined Grid with Transversal Bars," by C. Di Stefano and V. Ferro regarding the application of dimensional analysis and self-similarity theory. Topics include the differentiation of weir and orifice flow conditions, the influence of acceleration due to gravity to the weir flow, and the hydraulic behavior in stage-discharge relationship.

The e-NRTL model for computing the activity coefficients in solution of electrolytes was used for the first time, as the best of our knowledge, together with the Wilson's equation for evaluating the non-ideal behavior of the resin phase, in the prediction of multicomponent ion exchange equilibria. For this purpose, experimental data for the binary systems Ni2+/Na+ and Zn2+/Na+ and the ternary system Ni2+/Zn2+/Na+ using Amberlite IR-120 reported by Franco et al. [ 1 ] were considered. The results obtained showed that the major impact over the equilibrium modelling was caused by the inclusion of the Wilson's equation demonstrating the predominant effect of the non-ideality of the resin phase. No significant differences in the results (for the systems and ionic concentrations explored here) were observed when Bromley, Pitzer and e-NRTL equations were used to predict the activity coefficients in solution. Regarding the prediction of the multicomponent equilibria, it can be said that the most complex models: Pitzer's and e-NRTL ones, yield the best results. Again, the major impact in the improvement of the prediction was the inclusion of the Wilson's parameters. Finally, since the e-NRTL model allows to indistinctly work with both electrolytes and non-electrolytes, it could be possible to design modules for simulating the ion exchange operation in process simulations software like Aspen Plus®. [ABSTRACT FROM AUTHOR]

This approach is equal to using Eq. (17) with a head-loss coefficient HT ht . The sole aim of introducing a correction factor like HT ht is to obtain a discharge value, calculated by Eq. (11), equal to the measured one. In such cases, to correctly calculate the momentum correction factor, it is necessary to introduce the lateral nonuniformity as well as the nonuniform velocity distribution in the HT ht -direction. Aminpour et al. do not explain why the variable HT ht is considered as a function of HT ht . [Extracted from the article]

The measurements units of the USLE-MM soil erodibility factor are dependent on the exponent of the erosivity term. This circumstance prevents to compare soil erodibility values of sites differing by the value of this exponent. To overcame this problem, Kinnell (2018) suggested to relate the soil erodibility factor of the USLE-MM with that of USLE-M by a linear relationship with the objective to obtain a soil erodibility factor independent of the power of the erosivity term. The USLE-MB, which is a recently proposed model, has also a soil erodibility factor having measurement units common to USLE modelling environment. Kinnell (2018) also showed that the relationship between the power of erosivity term and the coefficient of proportionality of the linear relationship between soil erodibility of USLE-MM and USLE-M is site independent. In this comment, using the database of Sparacia experimental area, both this geographical independence and the linearity hypothesis between soil erodibilities were tested. The linearity hypothesis was not completely consistent for Sparacia experimental area while it was more satisfied for the comparison between soil erodibility of USLE-MB and USLE-M. The exponential equation proposed by Kinnell (2018) between the power of erosivity term and the coefficient of proportionality was demonstrated to be site-dependent. [ABSTRACT FROM AUTHOR]

Rectangular weirs, which are very common hydraulic structures used in irrigation channels as water measuring devices, can be used for measuring very small discharges as well as high flow rates. From a practical point of view, the availability of a unique stage-discharge formula that can be applied to different types of rectangular weirs would be of great practical importance. In this paper, Buckingham's theorem of dimensional analysis and the self-similarity theory are used to deduce the stage-discharge curves of different kinds of rectangular weirs such as slit and partially contracted weirs. The proposed formula is then calibrated using measurements from this investigation and experimental data from the literature. Compared with the available stage-discharge relationships, the results indicate that the proposed method can be used for the entire range of the ratio of weir width to channel width (i.e. both slit and partially contracted weirs) with acceptable accuracy. [ABSTRACT FROM AUTHOR]

Previous experimental investigations showed that a large proportion of total plot soil erosion over a long time period is generally due to relatively few, large storms. Consequently, erosion models able to accurately predict the highest plot soil loss values have practical importance since they could allow to improve the design of soil conservation practices in an area of interest. At present USLE-based models are attractive from a practical point of view, since the input data are generally easy to obtain. The USLE was developed with specific reference to the mean annual temporal scale but it was also applied at the event scale. Other models, such as the USLE-M and the USLE-MM, appear in principle more suitable to predict soil loss at this last temporal scale, because they include event plot runoff as an additional variable. At first in this investigation, carried out by using plot data collected at the experimental station of Sparacia, in Sicily (length, λ = 11–44 m, slope steepness, s = 14.9–26.0%), the circumstance that a single event in the year was responsible of approximately the 75% of total erosion during that year was recognized. Then the suitability of the USLE-derived models to predict maximum annual values of event soil loss was tested by measured events in all experimental plots (570 soil loss values for the complete data set, and 57 values for the data set of the maximum annual soil loss), in the period January 2002–March 2015, at Sparacia experimental area. This analysis showed the best model performance of USLE-MM schemes (Nash and Sutcliffe index, NSEI > 0.70) to determine the annual maxima of event soil, compared with the classical parameterization of USLE ( NSEI = 0.32). The development of methodologies widely applicable for estimating both the soil erodibility factor and the plot runoff coefficient will represent a step towards a diffuse application of this model. [ABSTRACT FROM AUTHOR]

• A flow resistance law was verified by measurements performed in a gravel-bed channel. • The effects of staggered arrangements of elements on flow resistance was investigated. • 2 different hydraulic conditions and 3 concentrations of elements were evaluated. • Element concentration effect on flow resistance was studied for staggered arrangement. Gravel bed flow resistance is affected by the shape and size of the roughness elements and their arrangement on the channel bed surface (spacing between elements, direction with respect to flow streamlines, and protrusion of the elements from the channel bed). Previous studies demonstrated that the flow resistance of open channel flows can be obtained by integrating the power velocity profile. This paper aims to study flow resistance in gravel-bed channels with different concentrations of boulders having staggered arrangements. At first, the equation relating Γ coefficient of the power velocity profile, and the Froude number was calibrated using measurements performed in a flume covered by hemispheric roughness elements for partially submerged and completely submerged hydraulic conditions. The roughness elements were evenly spaced (staggered) and arranged using three different concentrations of 9, 25, and 49%. Moreover, the relationship between Γ, slope, and the Froude number, calibrated using literature measurements performed with the same experimental setup but with a square arrangement, was tested for the measurements obtained with the staggered arrangement. The results showed that i) the Darcy-Weisbach friction factor can be accurately estimated by the proposed flow resistance equation, ii) the differences in flow resistance behavior between the two different investigated arrangements (staggered, square) occur only for the partially submerged hydraulic condition, and iii) for the staggered arrangement, skimming flow is reached for lower element concentrations as compared to the square one. [ABSTRACT FROM AUTHOR]

The aim of the paper is to validate the sediment delivery distributed (SEDD) model for estimating hillslope sediment yield estimates using net soil erosion values obtained by the cesium-137 technique. The cesium-137 technique provides spatially-distributed measurements useful to verify the predictive capability of a distributed sediment yield model. The application of the cesium-137 technique requires a calibration procedure to convert measurements of 137Cs inventories to estimates of net soil erosion rates. Rainfall and sediment yield data from 1978 to 1994 in a small Calabrian basin forested with eucalyptus trees, were initially used to calibrate, at mean annual temporal scale, the SEDD model applicable both at the morphological unit and basin scale. Then, estimates of net soil erosion were obtained using a mass balance model and the spatial distribution of cesium-137 inventories. The reliability of the mass balance model was verified by comparing the basin net soil erosion value obtained by 137Cs measurements against the mean annual value of sediment yield measured at the basin outlet. Finally a good concordance between calculated mean annual hillslope sediment yield and the corresponding net soil erosion values was proved at the scale of both the single morphological unit and the entire basin. In conclusion, the cesium-137 technique and the mass balance model confirmed the validity of the internal functioning of SEDD model. [ABSTRACT FROM AUTHOR]