Preconcentration and preseparation by electro-deposition of traces of metals

Several theoretical ideas on metal electro-deposition on inert solid electrodes, from solutions oftrace metal ion concentrations, are formulated. The results may be of importance in the application of electro-depositions as analytical preconcentration and preseparation methods.     

Ionization energies of liquids from energy distribution,quantum yield and second derivative curves

The energies of the lowest ionization band of eight liquids of low vapor pressure are determined from energy distribution curves (EDC), quantum yield spectra (collected electrons per incident photon as a function of photon energy), and second derivative curves (SDC) of retarding potential curves. Threshold energies from EDCs and quantum yield spectra agree if one takes into account a 0.15 e V shift caused by the spectrometer's rather low resolution and a small difference (0.15 eV or less) resulting from the use of approximate extrapolation methods. Threshold energies from EDCs and SDCs agree to within 0.1 eV after correction for the half-width of the high-energy branch of SDCs. Multiple ionization bands are exhibited by the SDCs of some of the liquids, and the observed splittings agree well with the results from gas-phase UPS spectra. A new spectrometer for the measurement of EDCs of liquids is described. The liquids studied are 6-chloro-1-hexanol, 2-ethyl-1-hexanol, ethylene cyanohydrin, ethylene glycol, 1,5-pentanediol, tetraglyme, triethylene glycol and tetraethylene glycol.     

The effect of ligand donor atoms on ternary complex stability

Formation constants of mixed ligand complexes of Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, and Mn²⁺,with cyadine-5′-monophosphoric acid (CMP) and various primary ligands such as 1,10-phenanthroline(phen), glycylglycine(glygly) and salicylic acid (sal) have been determined in aqueous solution at 35°C and 0.1 M (KNO₃) by potentiomeric measurements. The acid dissociation constants of all the above mentioned ligands together with their 1 : 1 binary metal complex formation constants were also measured at 35°C. In general all the 1 : 1 binary complexes follow the Irving-Williams order of stability. Further the binary metal complexes of primary ligands are more stable than their ternary complexes with CMP. For ternary complexes, Δ(log K) values seem to change from positive to highly negative as the coordinating atoms of the primary ligands were varied from N,N to N,O^? to O^?O^?. The higher stability of ternary complexes involving phen is due to its Π-bonding interaction with the above metal ions and the relative decrease in the stability of other ternary systems is due to the coulombic repulsion of donor oxygen atoms of primary and secondary ligands. Thus for ternary complexes the stabilities follow a decreasing order of M-phen-CMP > M-glygly-CMP > M-sal-CMP.     

A critical re-appraisal of the jet-thrust technique for normal stresses,with particular reference to axial velocity and stress rearrangement at the exit plane

It is shown that the thrust, T, exerted by a jet on the tube from which it flows, and the corresponding die-swell ratio, D, are closely related and dependent on the axial velocity and stress profiles at the exit plane. Velocity-profile data, calculated by Tanner using a finite element method, have been used to demonstrate that for a Newtonian liquid the reduction in measured thrust from the expected value arises from a re-arranged, non-parabolic axial velocity profile and the related re-arranged non-zero axial stress profile at the exit plane. The axial stress re-arrangement is the major effect.Using the correction-curve thus derived to determine the normal stresses, ν₁ + $\text{1}\text{2}$ν₂ aqueous and non-aqueous polymer solutions gives values that are higher than the “correct” results by a significant, substantial amount. The difference is not due to neglect of the second normal stress difference, ν₂, nor to the neglect of the wall pressure at the exit plane, which is shown experimentally to be very small. It is suggested that the difference, which is a function only of the shear stress (or rate of shear) at the wall, may arise from a difference in the stress profile associated with the velocity re-arrangement at the exit between Newtonian liquids and elasticoviscous liquids for which the extensional viscosity may be high.     

On the stability of phosphodiester-amide internucleotide bond

The stability of phosphodiester-amide internucleotide bond is compared in the deoxyribo and ribo series. The destabilizing effect of the 2′-OH group in the ribo series is discussed.     

On the charge distribution in manganese borides studied by X-ray photoelectron and emission spectroscopy

For the borides of the Mn-B system the values of binding energies of Mn 3p, $\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, $\text{2}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and B1s core levels were measured on an electron spectrometer. Depending on boride composition the variation of inner level energies is very similar, showing a change of sign in the region of the monoboride phase. The same variation has been observed for some characteristics of X-ray emission spectra from these borides. An attempt is made to understand which of the chemical bonding factors are chiefly responsible for a regular concentration dependence of the X-ray and photoelectron spectra.     

Therapeutic systems and controlled drug delivery

Therapeutic systems can provide pre-programmed, unattended delivery of a drug at a rate, and for a time period, established to meet a specific therapeutic need. The system can be designed to minimize the patient's intervention and to optimize compliance with the prescribed regimen. The ocular therapeutic system described here for the control of intraocular pressure in glaucoma delivers pilocarpine at 20 or 40 μg/h for one week, and fits comfortably into the cul-de-sac of the eye. The intrauterine progesterone contraceptive system described here represents a new approach to steroidal contraception that localizes the effect of the hormone progesterone to the uterus, delivering the hormone at a rate of 65 μg/day for one year. Both of these systems are designed to deliver drug into their immediate locale, and are thus topical dosage forms. The transdermal therapeutic system described here has been designed to deliver scopolamine across intact skin and into systemic blood to achieve an antinausea effect. The pharmacokinetics of scopolamine are such that, to minimize the time required for the onset of drug action, drug should be presented at an initially high rate, i.e. as a priming dose, to attain the therapeutically effective drug level, and then at a constant rate, so as to maintain the therapeutically effective level. This system functions according to the priming dose/maintenance rate design requirement.     

A robust multigrid approach for variational image registration models

Variational registration models are non-rigid and deformable imaging techniques for accurate registration of two images. As with other models for inverse problems using the Tikhonov regularization, they must have a suitably chosen regularization term as well as a data fitting term. One distinct feature of registration models is that their fitting term is always highly nonlinear and this nonlinearity restricts the class of numerical methods that are applicable. This paper first reviews the current state-of-the-art numerical methods for such models and observes that the nonlinear fitting term is mostly ‘avoided’ in developing fast multigrid methods. It then proposes a unified approach for designing fixed point type smoothers for multigrid methods. The diffusion registration model (second-order equations) and a curvature model (fourth-order equations) are used to illustrate our robust methodology. Analysis of the proposed smoothers and comparisons to other methods are given. As expected of a multigrid method, being many orders of magnitude faster than the unilevel gradient descent approach, the proposed numerical approach delivers fast and accurate results for a range of synthetic and real test images.