Analytical utility of coupled transport across a supported liquid membrane Selective preconcentration of zinc

A liquid membrane comprising 5-10% bis(2,4,4-trimethylpentyl)phosphinic acid in dodecane that is supported between an aqueous sample at pH 4.7-6.0 and a 0.1M HCl receiver results in uphill transport of Zn(II) from the sample into the receiver. With 2 ml of receiver, a 5 cm(2) membrane and 60 min dialysis time, Zn(II) is preconcentrated by a factor of ca. 13 when the initial concentration in the sample is in the range 1.5 x 10(-7)-1.5 x 10(-4)M. The enrichment factor is directly proportional to time up to 30 min since the transport rate of Zn(II) across the membrane is constant over this period. At longer times the flux is slowed as the system begins to approach equilibrium. The presence of other metals such as Cu(II), Co(II), Ni(II), Cd(II), Pb(II) and Fe(II) does not change the enrichment factor for Zn(II), even when the interferent is at a concentration high enough for the rate of transport (nmole/min) of the interferent and Zn(II) to be about the same. The flux of Zn(II) was about 40 times that of Cu(II) and 100 times that of Co(II) when their concentrations in the sample were equal. The other metal ions examined are not significantly transported.     

Comparative study of some constitutive equations characterising non-Newtonian fluids

This paper compares, in a general way, the predictions of the constitutive equations given by Rivlin and Ericksen, Oldroyd, and Walters. Whether we consider the rotational problems in cylindrical co-ordinates or in spherical polar co-ordinates, the effect of the non-Newtonicity on the secondary flows is collected in a single parameterα which can be explicitly expressed in terms of the non-Newtonian parameters that occur in each of the above-mentioned constitutive equations. Thus, for a given value ofα, all the three fluids will have identical secondary flows. It is only through the study of appropriate normal stresses that a Rivlin-Ericksen fluid can be distinguished from the other two fluids which are indistinguishable as long as this non-Newtonian parameter has the same value.     

Cataphoretic velocity of colloidal particles of lyophobic sols under constant current. A new setup to measure the boundary movement under constant current

Summary The migration velocities of the boundary of As₂S₃ and Fe(OH)₃ sols have been measured under constant current. A new set up for measuring the movement of the boundary under constant current has been devised. The changes in the boundary movement with time have been observed under constant current condition and it has been discussed and suggested that measurements of cataphoretic velocity of colloidal particles under constant current is theoretically more cogent than the measurements taken under constant voltage, because the changes in the resistance shown by the changes in the potential developed across the different elements in the U-tube at constant current give a more correct picture of what happens in the cataphoretic tube when cataphorisis takes place. A potentio-valve-voltmeter has been employed to measure the instantaneous changes of voltage across the mainU-tube without any time lag. This is a new device which has not been tried before.

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Zusammenfassung Die Wanderungsgeschwindigkeit an der Grenze von As₂S₃ and FeOH₃-Solen wurde gemessen, und zwar bei konstantem Strom. Eine neue Methode zur Messung der Wanderung bei konstantem Strom wird vorgeschlagen. Die Ver?nderungen der Bewegung der Grenze mit der Zeit werden diskutiert, und es wird vermutet, da? Messungen der kataphoretischen Geschwindigkeit von Kolloidpartikeln bei konstantem Strom theoretisch mehr Aussagen geben als Messungen bei konstanter Spannung, weil Widerstands?nderungen in den einzelnen Teilabschnitten des Kataphoreserohres bei konstantem Strom ein korrekteres Bild gibt. Ein Potentialr?hrenvoltmeter wurde für die Messung des Spannungsabfalls angewendet, so da? zeitliche ?nderungen verz?gerungsfrei aufgezeichnet werden konnten.

     

Search for ZH → l+ l- bb production in 4.2 fb(-1) of pp collisions at sqrt[s] =1 .96 TeV

We present a search for the standard model Higgs boson produced in association with a Z boson in 4.2 fb(-1) of pp collisions, collected with the D0 detector at the Fermilab Tevatron at sqrt[s] =1 .96 TeV. Selected events contain one reconstructed Z → e+ e- or Z → μ+ μ- candidate and at least two jets, including at least one b-tagged jet. In the absence of an excess over the background expected from other standard model processes, limits on the ZH cross section multiplied by the branching ratios are set. The limit at M(H) = 115 GeV is a factor of 5.9 larger than the standard model prediction.     

Multi-armed bandits based on a variant of Simulated Annealing

A variant of Simulated Annealing termed Simulated Annealing with Multiplicative Weights (SAMW) has been proposed in the literature. However, convergence was dependent on a parameter β(T), which was calculated a-priori based on the total iterations T the algorithm would run for. We first show the convergence of SAMW even when a diminishing stepsize β_k → 1 is used, where k is the index of iteration. Using this SAMW as a kernel, a stochastic multi-armed bandit (SMAB) algorithm called SOFTMIX can be improved to obtain the minimum-possible log regret, as compared to log² regret of the original. Another modification of SOFTMIX is proposed which avoids the need for a parameter that is dependent on the reward distribution of the arms. Further, a variant of SOFTMIX that uses a comparison term drawn from another popular SMAB algorithm called UCB1 is then described. It is also shown why the proposed scheme is computationally more efficient over UCB1, and an alternative to this algorithm with simpler stepsizes is also proposed. Numerical simulations for all the proposed algorithms are then presented.     

Rapid communication: $$K_{S}^{0}$$ Production from beryllium target using 120 $$\hbox {GeV}/\hbox {c}$$GeV/c protons beam interactions at the MIPP experiment

We have measured the cross-section for the \(K_{S}^{0}\) production from beryllium target using 120 \(\hbox {GeV}/\hbox {c}\) protons beam interactions at the main injector particle production (MIPP) experiment at Fermilab. The data were collected with target having a thickness of 0.94% of the nuclear interaction length. The \(K_{S}^{0}\) inclusive differential cross-section in bins of momenta is presented covering momentum range from \(0.4\,\hbox {GeV}/\hbox {c}\) to \(30\,\hbox {GeV}/\hbox {c}\). The measured inclusive \(K_{S}^{0}\) production cross-section amounts to \(39.54\pm 1.46\delta _{\mathrm {stat}}\pm 6.97\delta _{\mathrm {syst}}\) mb and the value is compared with the prediction of FLUKA hadron production model.